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[Question] [ Most regenerative monsters possess a "core" of some kind which must be destroyed in order to kill them. I've noticed this trope at least a dozen times in Japanese media specifically. In fact it's so prevalent that there must be a reason WHY monsters are like this (besides having an Achilles' heel). So I began investigating the subject. Turns out that when a monster is smashed to a pulp, a core is a good thing to have. 1. It acts as a beacon and centre of aggregation for the scattered monster flesh. 2. It serves as a power source for said flesh, which now must survive without organs until they are regenerated. 3. That is usually where the monsters brain is kept. With this knowledge, I designed my monsters accordingly: They are artificial lifeforms manufactured by inserting a spherical core into a sort of putty liquid (let's call it monster-sauce). The sauce aggregates and hardens around the core. Then signals from the core make the cells in the monster-sauce differentiate into the various parts of the monster. This is a functional fictional manufacturing process because each core is identical and can be "programmed" to create any monster. Meanwhile the monster-sauce is homogenous and easy to mass produce. Dead monsters liquefy and are recycled while injured monsters can be regenerated by dipping them in the monster sauce. In combat, no matter how many times the monsters are pierced, slashed or crushed, they will always keep regenerating as long as the core remains intact. The smallest of monsters are only about as large as their core, thus a single attack is usually enough to kill them. The larger monsters are a different story. Their cores are more heavily defended: layers of hardened flesh conceal and protect the core. When a monsters core is destroyed they will disintegrate, turning back into the monster-sauce. However, if their core survives the traumatic injury (no matter how severe) they will begin regenerating following these five steps: 1. Liquefy. 2. Aggregate towards the nearest core. 3. Form a spherical cyst. 4. Harden and differentiate. 5. Return to original shape. Foreign objects will only be removed while the monster is in liquid form. Afterward it is too late. Things like arrowheads will stay embedded in the monsters flesh until they begin regenerating again. The core is a solid sphere about the size of a football with the consistency of quartz. So I ask you, valiant monster hunters, what melee weapon would be ideal to slay such a monster? The technology level is pre-industrial. [Answer] For the sake of the answer, I will assume "destroying a core" means splitting it into 2 or more pieces. Option 1 (Monster's flesh has low shock absorbance, strong humans): In this case, a hammer would most likely deal enough damage to split the core in half, through force transfer. Option 2 (Monsters flesh has high shock absorbance, humans are slightly stronger than usual): In this case, one would have to have knowledge of where the monsters core is. By using the characteristics of things remaining embedded till the core is destroyed, one could use a weaponised hammer and long rock nail, to first embed the nail in the monster's flesh, just near the core, then smash it to deliver full force to the core, bypassing the flesh. Alternatively, you could hold the monster down and get a sledge hammer if you aren't confident about breaking it in one blow. Edit: If the humans aren't stronger than normal and at most the monsters are made of wood level toughness, working solo, a powerful hammer blow would work, or if the monster is large and tough, using a hammer or chisel would easily fell them. If you and your pals team up to fight a monster using a pitchfork or polearm to hold the monster down (idea stolen from Daron), and then hammer away at the core, or now that it's pinned, the hammer and chisel would work quite well. TL:DR If working solo, either play whackamole with their chests if the monsters are weak, or use this bad boy. [![Hammer and chisel](https://i.stack.imgur.com/t8zxQ.png)](https://i.stack.imgur.com/t8zxQ.png) Otherwise if you and your pals team up, restrain it with polearms and then smash it like its a controller and you just played the worst game of your life. [Answer] Introducing the Guisarme [![enter image description here](https://i.stack.imgur.com/yyeq0.png)](https://i.stack.imgur.com/yyeq0.png) What the heck is a guisarme? It is a hooked polearm with an extra sticky-uppy bit attached to the side. What the heck is a guisarme for? That question has puzzled scholars for a million years. But now the answer is clear. It is to fight core monsters. You cannot destroy the core while it is still inside the monster. You'd need to penetrate the goo with enough force left over to shatter the core. And if you don't hit hard enough, then the goo heals over, and you have to hit it just as hard the second time. The goo cushions blunt trauma and the core is only vulnerable to blunt trauma. It is the ultimate defense. You cannot poke the monster with a sharp thing, then retreat and wait for it to tire and bleed out. It has no organs or anatomy. Instead you must outnumber the monster by holding it down with half a dozen polearms. Once all the limbs are pinioned against the ground or a nearby tree, someone moves in, carves open the chest and extracts the core. Then they shatter it with a small hammer. Of course you need to outnumber the monster to do this strategy. But that's just common sense. Your monster hunters do this for a living. You can't support your family as a monster hunter if every job is a life-or-death struggle. You want to be confident you can kill the monster, get paid, and then return to your family with the same number of arms and legs as when you left. So ride out and find out how many monsters there are. Then ride away and get six dudes for each monster. If necessary enlist some of the villagers who hired you. These guys are inexperiences. They might die but they are willing to die since the monster is attacking their village and THEIR families. --- This is why monster hunters have a bad reputation. They roll into town and before you know it six of your sons and husbands are dead. Then they roll out unscratched. --- Another good weapon is the trident. If your monster hunters live by the sea they might have tridents lying around for fishing. Otherwise tridents are harder to believe than polearms, since they were not used for regular warfare. Edit: The best improvised weapon is one of these bad boys: [![enter image description here](https://i.stack.imgur.com/7vnLp.png)](https://i.stack.imgur.com/7vnLp.png) A pitchfork! As mentioned above the hunters sometimes enlist local farmers to defend their villages. The farmers use their pitchforks as improvised polearms. A spear with a crossguard might work in a pinch, to prevent the monster running up the spear to get you. You get the idea. The ideal weapon is a long thing with two or more pointy bits at the end that you stick in the monster to hold it in place. [Answer] ## Torches for starters... And anything else which burns things down. [![Torch burning photo](https://i.stack.imgur.com/7VmbK.jpg)](https://i.stack.imgur.com/7VmbK.jpg) Photo from Andrew Dunn, [wikimedia commons](https://commons.wikimedia.org/wiki/File:Lewes_Bonfire,_discarded_torch.jpg) You need to pin them down in order to do any other safe and meaningful action. You could pin them with hooks and spears, but it's going to be hard to maintain a strong grip if the meat around the point of impact liquefies. Think like sticking a hot knife into a butter cube : At first, it'll hold, but then it will slowly slide as the butter melt. On its side, fire will melt the body, yes, but since the liquid cells are still "alive", the fire will continue to burn and prevent a true regeneration. Add in this : > > Step 2 : Monster liquid aggregate towards the nearest core. > > > This makes it an homing weapon the monster just can't get rid of1. It'll be like melting a candle (or butter stick) from all sides with a blowtorch. If they're not becoming all liquid, it will make any of them paralized in pain2. Now that your target is very soft if not liquified, it is now unable to defend. You just need then to tighten your fireproof pant, gloves and boots and... ## And get hammers for dessert [![A drawing of a man striking with a sledgehammer](https://i.stack.imgur.com/snmQO.png)](https://i.stack.imgur.com/snmQO.png) Archives of Pearson Scott Foresman, [wikimedia commons](https://commons.wikimedia.org/wiki/File:Sledge_Hammer_(PSF).png) Hammers are your best tools of shattering : It's heavy-duty, strong and packs a punch. Since your target cannot dodge this unwieldy giant, it's your best bet in shattering the core while being easily doable in these conditions. If you work in teams, one should take a good, two-handed sledgehammer to finish the job, while the other defend and burn any left-over. If you're alone, a torch in one hand and a smaller hammer should do the job. If the core is a bit too big and covered by some tough meat, you can add in a chisel to make some precision strikes and weaken the whole structure : Whether or not the meat manages to regenerate, your chisel will still be waiting for your next blow to go deeper :). --- 1 : The Guild of Dungeoneering deny any responsibility in forest, wheat field, house, and other elements surrounding the monster starting to burn. It is the responsibility of the quest poster to ensure that forests, wheat fields, houses and other elements are protected and out of possible monster's burning reach. 2 : The Guild of Dungeoneering will not pay for psychological care due to "traumas caused by hearing plenty of monsters screaming horrifically for their lives". The Guild of Dungeoneering would like to remember that monsters have no family or friends and don't feel pain. [Answer] /This is a functional fictional manufacturing process because each core is identical and can be "programmed" to create any monster./ Reprogram [![remote](https://i.stack.imgur.com/qkHXs.jpg)](https://i.stack.imgur.com/qkHXs.jpg) Destroy a perfectly good monster core? With all that fresh sauce? That someone else paid for? So wasteful. The owners of these monsters must have codes to reprogram them. Use those codes, commandeer the monster and wipe it, then reprogram it to be something more to your liking. [Answer] ## A bomb Yes, a humble old bomb. Barrel full o' gunpowder. Ignite. Yon core is ceramic, which abhors shock. Blunt damage is naught but shock. Should that core not splinter, it will fly many furlongs from yon goo. Wherein is the flaw? [Answer] # Blunt weapons How do you strike at a core that is at an unknown location correctly and destroy it? The only right answer can be a blunt weapon. Even if you know the sphere is where the brain is, the sphere can still be relatively small compared to a normal brain. Anything that pierces or slashes is at a disadvantage. You just have to hope on a direct strike againsylt the core to kill the monster. But this is further complicated by the form and nature. It is a hard core inside a hard shell. Any direct strike has a large chance to deflect, doing minimal to no damage. Blunt weapons circumvent this. These weapons try to maximise the energy behind a blow, putting it all into a large area where you strike. Each part gives some of the energy to the next, allowing blunt force to go deep. A strike not only requires healing, it can also damage the core without ever touching it. Will it damage it? Probably not immediately or enough to destroy it. But this problem is much worse with other weapons. Here you have a chance to go deep. If the flesh tries to heal it leaves the core more vulnerable. It'll liquefy, allowing you to go deeper with a blunt weapon and hopefully hit close enough to damage the core. A durect hit is also more likely. If it hits the outer shell of the core the energy will go through the outer shell, changing the shape and probably damaging if not destroying the core. So grab the maces, morning stars and big tree branches. Smash a head and hope to kill the core. If not, look for it in or around the creature and apply direct force. You use a hammer to smash things. Never a sword. [Answer] The obvious answer for destroying the core is, of course, a big ol' hammer. Give it a few good whacks, and you'll shatter the core, ending the monster for good. However, before you break the core, you're going to need to get the core out of the monster - and here's what everyone is missing. Yes, you might be able to fashion some sort of crazy spike that stabs into the monster and shatters the core while it is still wrapped in its warm goo, but that's (literally) hit and miss. You need a strong arm and good aim to do that, and that's a great way to lose a bunch of good fighters. Or at least your arm. Instead, you want a modified ballista - a giant crossbow capable of hurling telephone-pole-sized missiles across the field of battle. The ballista itself can be largely ordinary - a huge crossbow, reinforced and bolstered with heavy springs - because the real key is the ammunition. The ballista bolt needs to be heavy, streamlined, and most importantly, tipped with a mesh of incredibly sharp blades. The blades will slice through flesh like a knife through pudding, but not the core - but because of the terrible speed of the bolt, when it slices into the creature, it will capture the core in the mesh and continue out the other side, landing (hopefully) a good distance away. As the rest of the monster begins its melt-and-reform process, the workers on the other side of the field can grab the core (removing whatever goo still stuck to it), move it to a hard surface, and smash it into useless shards. To use this method, you will need three teams: 1. The "worriers", who will use fast horses and long, light weapons, to annoy the monster and grab its attention, to keep it away from the other teams 2. The ballista team, who will set up the weapon, load it, wind it, aim it, and fire it at the monster 3. A group of mounted, well-muscled troops armed with knives and hammers, to grab, clean, and smash the core [Answer] Frame-challenge: don't destroy it. Rip it out of the sliced-up monster (swords would do fine here), immediately put it in a box too small for coalescing around. It's inert. Eventually sell it at the village. Should fetch a reasonable price due to its potential for experimentation. Even if it can't yet be reprogrammed to the holder's purposes, wheels are turning. [Answer] <https://upload.wikimedia.org/wikipedia/commons/8/82/Mode_Shape_of_a_Tuning_Fork_at_Eigenfrequency_440.09_Hz.gif> The ideal weapon is a diamond Diapason (Tuning fork), with a incredible thin tip, that penetrate the material of the core, thinner then a hair. Then the whole assembly is set into vibration, resulting in either slicing damage to the core- or if done right, it just gets the cores shell to swing and tear itself apart because there is that one frequency it can not withstand. Such a weapon would be fragile and difficult to handle, needing years of training and the ability to improvise. After all corse might have different frequencies - or worser still, soft spots, were the fork will only produce bloody carnage. So first assault you slice a wound to the core, then you place the fork, finally you "sing" the core apart by applying controlled vibration. [Answer] Pointed weapon The weapon must pierce into the monster flesh in order to reach the core so it should be a pointed weapon. An arrow or a spear may do that but not edged or blunt weapons. You can use a bow or a spear-gun to throw the weapon. With trial and error method, you can roughly estimate the strength needed to throw the weapon to a given sized monster. ]
[Question] [ In modern day society, few or many people have been fascinated with integrating robotic parts to their bodies. But sometimes that idea is taken to the next step, in which people want to have their entire bodies become robotic in nature. So let’s say that humanity is capable of doing that. Normal people would have robotic brains, limbs, and other parts, and are somewhat connected to the internet. However, humanity isn't advanced enough to make limitless energy (essentially where we stand in energy production terms). What are a few problems or disadvantages that would arise from humans turning themselves into robots? [Answer] Currently, robots do not last as long as humans. Even old, restored cars tend not to last as long as humans, and still be functional. And human bodies do not tend to become obsolete the way modern technology does. A new body every two or three years? Think of the costs, if an iPhone is around $1,000. And, of course, there is always the security, the security upgrades, and the hacking. We get upset when our identity is stolen, so our entire bodies? Imagine the business Norton would do. It puts an entirely different twist on 'Anti-virus software'. [Answer] The term here isn't robots, it's cyborgs. This is also the premise of Ghost in the Shell. The maintenance and security problems will be an expensive problem in contrast to an organic body that is semi-self repairing and sort of secure. Organic brains or memories can be manipulated(see con artists, infrasonic as a source of ghost sightings, or the work of Elizabeth Loftus), but they cannot be outright controlled or deleted in the same way cyberized brains can be. You've also created some very interesting philosophical questions as an inevitable result of this technological advancement. What does it actually mean to be human when every part of a human can be replaced? It's a similar problem to the Ship of Thesseus. If no component of "you" is the original organic parts, are you still you? It is also likely possible that this technology allows one to replicate your brain, because if brains can be entirely digital, they can be easily duplicated. Ghost in the Shell uses the concept of the Ghost as a result, the idea that there is something innately human, which is really just another word for a soul. You'd have to answer the philisophical question as to whether a soul exists. [Answer] OK. So. Here's the assumptions I'm making with this answer: 1. Humanity has figured out how to transfer their minds into robot minds 2. These (base) robot bodies are on par with human bodies, in terms of dexterity, strength, etc. 3. Parts can be replaced and repaired. All of them. If we can upload to one brain, we can transfer that brain to another brain, etc. The biggest problem that I forsee is population. That is, once your population is made out of robots, it no longer expands. It can only shrink. Regardless of how tough the robot body is, things happen and bodies are broken. Occasionally, that will be the "Mind" portion. But, as there's no biological humans left, you can't have babies and can't add to the human population. Now, you can add to the population with AI, but AI by definition aren't going to be humans. Your population of humans will dwindle, getting smaller and smaller. Similarly, as mentioned in @Adam Reynolds' answer, you might be able to replicate human "digital" brains, but... Are they human? There's also the issue of religion. Many religions have the concept of a soul - Is the person's soul linked to their body? Do they "Die" when their brain is uploaded, or by uploading are they foregoing the potential afterlife? Do AIs, or copied human brains, have souls, and how does the religions treat them? Religion is a huge can of worms for a society that is in the process of uploading, but I'd imagine if everyone has already uploaded then that problem has largely been "solved" or isn't really thought about by people anymore. [Answer] # Multiplicity If you can upload yourself into one robot body, why not 1000? Travel the world...simultaneously! Of course, you need to buy all the bodies, but if each one can earn money on its own, then what's to stop your personal collective from growing without bound, until you can populate an entire new planet...all by yourself? # Humanity At first, humans will want to upload into humanoid bodies. But why stop there? Some freak will want to inhabit a robotic spider body. And another will want to be a huge cyborg elephant monstrosity. And yet another will want to become a commercial robotic bakery oven. Eventually, all the robots in society may, in fact, be humans (or former humans, depending on how you look at it). At that point, what exactly does it mean to be a human? Or does it? # Space Exploration Obviously, travelling in space is much easier if you don't need the extensive life support systems that humans require. So robotic bodies would vastly simplify space exploration. Perhaps the ships themselves will be uploaded humans, as individuals or even families/collectives. The worst outcome of all is not getting shot out an airlock (which wouldn't exist on a ship without useless air in the cabin). The worst outcome is getting detached from the ship and floating aimlessly until your power supply ran out. And if the robots have a very long-lasting supply (micro-fusion or whatnot), then that could be a very long time indeed. On the plus side, they could have a "stasis" mode which lets them shut down until someone comes and rescues them. They could float in space for thousands of years, only to be accidentally discovered, repaired, and revived, little the worse for wear (cosmic rays will take their toll, but with adequately robust neural networks, will only result in memory degradation, rather than absolute mental loss). # Contemplation Lots of folks said that the robot humans would stop advancing. I think this is an unnecessarily and wetware-chauvinist point of view. But the way in which I think an appearance of this might occur is that some humans might want to upload into a robot body that happens to be a structure. A building. Yes, some freak will want to become a building. Others will follow. And without locomotion, they will be limited to whatever the building inhabitants do. They could still communicate on networks, presumably. But they would be the equivalent of conscious plants. They might devolve into extensive navel-gazing, and slowly lose all motivation to advance. Or, they could use the free time to explore the limits of science and art and become the best mathematicians and musicians in the galaxy. [Answer] Stagnation Just imagine the ultra wealthy never dying, just keep accumulating the wealth of society by preying on those weaker than them. People like Putin, who made himself "president for life" and others like him never dying. In a society like that, change would be almost impossible. Death is ultimate reason to give someone else a chance. [Answer] ## We are the Cybermen One of the primary villains in Doctor Who, the Cybermen are pretty much exactly what you are describing. They are described as normal run-of-the-mill people from the planet Telos. Originally completely organic, they gradually replaced various limbs and organs with robotic parts, reasoning that they were more efficient. Eventually, they went all the way, replacing their brains and thus transitioning from cyborgs to the "human mind controlling a robot" that you appear to be looking for. Unfortunately for them, these changes caused them societal problems. The 11th Doctor aims out up pretty nicely, when he tells John Lumic (their creator), > > Everything you've invented, you did to fight your sickness. And that's brilliant. That is so human. But once you get rid of sickness and mortality, then what's there to strive for, eh? The Cybermen won't advance, you'll just stop! You'll stay like this forever. A metal Earth with metal men and metal thoughts, lacking the one thing that makes this planet so alive: people! Ordinary, stupid, brilliant people! > > > This apathy, combined with their inability to reproduce, was their downfall; over time they gradually withered away, ultimately dying out due to attrition. [Answer] The fully robotic humans would die out, many of the cyborgs would already die out. They would eventually solve this but be more robotic intelligence than human intelligence in a robotic body. The problem is that your body provides a lot of incentives. The incentive for gathering food, incentives to protect against damage, incentives to procreate and incentives to keep breathing to live. If you start replacing bodyparts all that is left is intelligence, but like a computer it does not have a will to perform tasks to keep itself "alive". At best it has systems and programs that it will keep running until it simply fails due to energy shortage or similar. The solution would be to add programs that simulate this behaviour, but that is kind of the opposite of what this type of change is trying to achieve. It would be likely that these people would look for a "superior" behaviour simulation that gives them the best results in productivity for example, meaning the robots would all become more and more similar to each other as they would also copy knowledge, skills and capabilities off of each other. Within a short period after such a change the person they were will be a fraction of the uniform robot that is layered on top of it. [Answer] What about the [teleporter problem](https://en.wikipedia.org/wiki/Teletransportation_paradox)? Uploading your consciousness into a robotic body might even turn out to be impossible. How will the uploading be done anyway? Destructively, destroying your brain in the process? But what if the brain wasn't destroyed instantly? You will perceive that a robot with your memories walks away, and then you are killed. You die. You aren't uploaded. You are dead, while a robot emerges which is merely emulating you. [Answer] A man can create a robot, but the other way around is impossible. Everything we create is just to make our lives better, or to help us things easier/faster, to live longer. Disadvantages: - Reproduction of humans. Once the last human is gone, we are gone forever. - Robots will never be capable of having such "elastic", natural movement. - Can you imagine a life where people look almost the same? That would be so boring. Lack of diversity is boring. Can you fall in love with a robot or any other "thing" that lacks emotion/feelings? Problems: - Security. Most important, when a common connection is used(e.g internet connected parts) - Nothing lasts forever. Not even metal or any other stuff. There is something that can destroy something else. We might live longer, but not forever. [Answer] Quick overpopulation and war. "If you can upload yourself into one robot body, why not 1000?" <https://worldbuilding.stackexchange.com/a/170102/581> You know those weird cults that just breed as much as physically possible? They can now copy-paste themselves. Uh-oh. Every sufficiently rich person now has the option of converting wealth into copies of themselves. Being betrayed by a copy is always a risk, but a few individuals with weird minds will have perfectly loyal armies. I doesn't matter that the average person wouldn't be interested. A few outliers will suddenly become a lot. The normals will try to stop them while it's possible. The replicators will take refuge in any contry that doesn't actively persecute them. And when that fails, they'll fight with the numbers they already amass. War will be almost inevitable, but not completely. A quick worldwide consensus could build before any replicators can make a stand against existing governments, assuming reproduction is slow enough. If that happens, or if the war is won by the normals, who still want a society close to what came before, there's a remaining issue: They'll have to restrict reproduction. There are very good reasons why societies on the freer side of the spectrum have a taboo against restricting reproduction. That power gets abused every time. Yet we'll have to try again. [Answer] What about everyone else? Here is a list of problems that could occur if a minority population (or majority disenfranchised population) can't, or won't, 'upgrade.' Class friction 'Upgrading' to a robot isn't free. It requires quite a lot in the way of resources and expertise. So, ostensibly, some people can't afford it. How do these people react to being surrounded by nearly immortal rich people? How do the nearly immortal rich people treat these organics? Keep in mind, fully organic people can still have children, while ostensibly, the mechanical population can't. Income disparity Given a hundred, or two hundred years, an effectively immortal human could accrue an enormous amount of wealth relative to someone who only has a working lifespan worth of wealth to draw from. Even assuming they're not interested in building a financial empire, a mechanical human's operating costs are just so much lower than a standard human's. They have no need of food or shelter, or possibly even transportation. They don't need to sleep, either, and they don't feel fatigue. They can work 80 weeks and still have plenty of time for hobbies. Seeing this, the income gap between mechanical and biological humans must be extremely severe, and the wealth gap between them will only grow as time moves on. Medical Treatment At what point does it become more cost effective to simply replace a failing human mechanism with it's mechanical counterpart? What happens to anyone who can't afford that? What happens to medicine in general if the solution to most medical problems is just replace the part? Would anyone bother training in how to treat diseases, infection, or any manner of other medical conditions? Even if the knowledge doesn't become lost, the skills and practices might be. What does that mean for people who haven't, can't, or won't become mechanical? Disease and pollution An largely mechanical populace no longer has any incentive to maintain basic sanitation. Machines don't catch colds. Similarly, toxic substances no longer pose a serious threat to a large percentage of the population. Why bother addressing these problems if they're a non-problem for most of humanity? Or, at least, most of humanity that donates to political campaigns. What does that mean for anyone left behind? Food and agriculture Making sure everyone stays fed requires a lot of people working together. At what point does the economy that supports world wide agricultural industry start to collapse? Note, currently, in order to make agribusiness profitable, most governments make heavy use of tariffs and subsidies. A minor sea change in how important governments believed these programs to be could cause widespread famine among those who are still biological. Workplace safety and labour laws Tons of people are now made of metal and don't need to sleep. Also, lost limbs are replaceable. This may cause drastic shifts in what is considered an acceptable amount of money to spend on ensuring occupational safety and reasonable working conditions. [Answer] 1) If you make a backup copy of your own mind/body, does that backup copy have the same rights as you? Does it have every right to demand that it not stay in storage and instead live in your house? 2) People of different levels of income might be able to afford different levels of processing hardware. It could become the case that a billionaire links a remote server farm to their mind and now has thousands of times the processing power of the average person. Would they dominate politics? Would they outsmart one businessman after another and eventually gain a monopoly on all industry? 3) A whole new kind of racism. Technological humans may look down on biological humans as inferior. Biological Humans may treat Technological Humans as merely machines. 4) If people become machines they probably don't need to eat, so all food production ends. Ordinary farm animals that are not well suited to living in the wild become endangered or extinct. 5) Robotics today are less energy efficient than the human body. For example the human body typically consumes many times (probably about 10X) less energy when walking compared to prototype walking robots of today. 6) Engineers can create designs much faster now that they can directly input designs from their mind into the computer, rather than using a keyboard and mouse. The rate of technology development now accelerates drastically. Now no-one can keep up with learning all the tech that comes out seemingly every day. 7) People may become very reliant on internet access. They can now access any information on the internet just by thinking about it. It sort of becomes like the way we access our own memories. It becomes hard to tell what is your memories and what is external information. People become so reliant on network access that they are unable to function when they get stranded out of range of a good signal. 8) Many people may choose to just live in virtual reality. 9) Its probably the end of sports as we know it. The bodies of pro athletes would need to be standardized in some way, like the way a field or a ball is. Otherwise things could become quite unfair. 10) No more handicap parking at the store. Not really a problem, but at least a possible change. [Answer] Intelligence explosion. One rich and intelligent engineer, let's call him Elon, will devote all his efforts to making himself smarter. This is not possible with a classic biological brain, but it can be done with artificial hardware and software. As he gets smarter, this process gets faster, until the rest of humanity are like mice at his feet. This Singularity might be good or bad for the normals; there's no way to know until it arrives. [Answer] I almost feel that humans, if they became robots, would be rendered braindead eventually. This is because the human brain can only hold a limited amount of information, and even if you transferred consciousness digitally, it would still remain the same. ]
[Question] [ This particular coven operates as a powerful and wide spanning enterprise focused on accumulating power to direct the world in ways that align with their interests. This group operates similar to HYDRA or COBRA, recruiting members mostly from young people seeking power in society, with the intention of using them to expand the coven's interests. These individuals may rise in the hierarchy due to their successes and eventually become key members and important players. Witches gain more power through a dark ritual, which steals the life force from an unwilling victim and adds it to their own, making their magic stronger. Rituals are performed with a circle of 5, with each witch sharing in the power gained. This means that a young witch will join the coven in the hopes that, one day, she will be promoted high enough to start performing such rituals to eventually become a goddess. The process of being versed in enough occult knowledge to perform spells takes decades (the equivalent of obtaining multiple PhD's, for example). So a simple human would have to study REALLY hard (while also being a servant for the older witches), for a lifetime, in order to eventually get to the point where the other witches will grant her the opportunity to start taking part in the ritual. The problem is that many of the higher ranking witches view these prospective members as mooks, using them in irresponsible ways. Higher ups do this to shield themselves from having to do dangerous tasks, leaving lackeys to take all the risks. Using them as expendable shields against authorities or competing criminal organizations, or as run of the mill goons who can be easily sacrificed when they outlive their usefulness, is problematic for long term survival of the coven. Interns can't exactly unionize because...well, it is a criminal organization. Expecting them to take up pickets and march through the streets demanding equal pay and treatment is unlikely. How can I encourage my underlings to use their recruits more responsibly and prevent them from being expendable? [Answer] This might be the first problem I've seen that could actually be made better by a pyramid scheme. In order to exert this level of control over world events, your witches use spells that require more magical energy than any single human can possess. Witches will mystically bind themselves to their subordinates, which accelerates their ability to learn and allows the witch to use some percentage of each subordinate's magical energy (direct subordinates, plus anyone else all the way down the tree). These "commissions" accumulate as you move up the hierarchy, leading to big "bonuses" to those at the top. For example (adjust your own numbers as needed), assume each human has 100 "points" of magical energy, the binding bonus is 5%, and each witch had 5 subordinates. The lowest level of the hierarchy would have only their 100 points. Those on the second level would have 125 points (100 + 5% \* 5 \* 100). On the third, 256 (100 + 5% \* 5 \(125 + 5 \ 100)). Those at the top of a large tree can leverage their bound subordinate's power to accomplish nearly superhuman feats. This creates a strong incentive to keep your tree full and healthy. Wasting someone at the bottom level means you lose their power commission. Commissions compound as you go up the tree, so a loss at any level will be felt. Instead, the incentive is to protect those in your organization and keep them invested in training, increasing their own power, and eventually bringing in their own subordinates. [Answer] There's a culture of master/apprentice relationships, where each high-ranking witch has a few protégés. The high-ranking witch encourages competition between her apprentices, who are eager to gain her favor. However, this works hierarchically. The high-ranking witch is one of a few apprentices of an older, even more powerful witch. Members are held accountable for the failures of their subordinates, so competition between high-ranking witches gives them an incentive to make their apprentices as effective as possible, as this reflects well for them. Since it takes a long time to train, it would be a wasted time investment to throw away an intern who's already been trained in the basic stuff their master doesn't want to teach some new guy all over again. That's a solution that doesn't require any magic, just a few tweaks to the workplace culture. The organization can be expanded as a pyramid without breaking this effect. [Answer] You could turn the system so that the lowest-stage witches need a power investment from the witch higher up. Say, they don't come to the coven themselves, but instead more experienced witches need to find new recruits and become their patrons. In order for these new witches to be able to do at least something, and also to ensure their loyalty, elder witches need to invest them with the part of their power. If the young witch dies, the power is lost irretrievably. This way, there's a balance between enlisting young helpers and keeping powers for oneself. Also, there is a necessity to protect them and keep them alive - even if elder witch plans to sacrifice her helpers later in a dark ritual to retrieve the power back. [Answer] They can advance when they realize the occult they are studying is a lie. Western society does like to promote this idea: "one studies for their first part of their life, producing nothing of worth, until they graduate, and then they stop learning and go do things." Every aspect of that phrase is false, but it is the rationale we instill in students in order to get them to suck it up through college. This process becomes absurd when one starts to look at learning phases which extend the lifespan of the learner. The witches move up out of the intern status once they realize this. Fundamentally, the older witches better understand a fundamental problem: if they die without ascending to goddesshood, everything they learned and taught disappears with them. Witches which don't understand this tend to lead covens that cease to exist soon thereafter. Thus, from evolution, we can expect the successful covens work around this. There's plenty of ways to make this happen, but my favorite is to make it so that, once you have learned all of the occult (a lifetime of work), you can synthesize this into an obvious conclusion: the path described in the training doesn't lead you to any lasting change -- just suffering. And yet, there's something cloying about the end-state the elder witches describe. It looks like it should almost work. The "correct" path may be tremendously close. It's just not the specific path taught in witch school. In such a system, the eldest witches would certainly be plying the universe for its secrets in the best way they know how. But they're just one witch. They can't try everything. Thus, they should rely somewhat on the apprentice witches. If an apprentice witch finds something small that the elder witch missed during her training, she may be able to build upon this small thing and bring the entire coven closer to the right answer. I'd recommend there be an interesting phrasing in the book about how only a child can lead to the true path to goddesshood. Many witches may mistakenly translate that into child-sacrifice, which would do well to keep the evil flavor you appear to seek alive in your covens, but perhaps the eldest witches figured it out. Only the child-like mind can possibly find the subtle overlooked thing which makes it all work. Think like that for a while, and then look at social constructs you consider to be "respectable and mature." Look at the father who volunteers at the YMCA to help keep kids off the streets, or the martial arts teacher taking his time to improve his students' lives. Or perhaps it's the minister or priest who truly strives for greatness for their entire congregation (and maybe, just maybe, the entire world). Look at how they act, and borrow that for your witch covens. [Answer] They must feel their underlings' pain Part of the initiation involves a sharing between higher and lower and peers, after which each human will forever feel some of the (physical) pain of the others. This means that some coven members will encourage someone else's underlings (with whom they have not shared) to be fodder and get killed, while protecting her own underlings and the life of her peer (whom she has shared with). This encourages intrigue within the group while seeming to cooperate. It also means that initial screening will weed out folks prone to headaches, chronic pain, or severe cramps, regardless of how good a witch they might make. [Answer] No "employee" that takes that much training would ever treated as trivial. You are probably picturing something like a gang where you lose one of your street dealers, and you just go out and recruit some other kid off the streets to take his place a few days later. In fact, this being a criminal organisation makes the replacement of intelligent subordinates even that much harder, because you need to find someone both desperate enough to break the law, and competent enough to master what you are teaching. Your senior members NEED new acrolites to grow their influence, and if they keep leaving or dying after 1-5 years, then the organization will crumble. The Solution Recruit separate thugs for the sake of being thugs. Your coven has enough power and wealth to attract the normal desperate masses that would join any other criminal organization; so, 95% of the people you recruit will never be in it for the magic. They just have a job to do, and you pay them well for it, but when you find someone with the intellect to make more of themselves, you choose them to be an apprentice and start the long task of teaching them the ways of the arcane. From that day on, they would likely be kept as insulated as possible from the daily dangers of the illegal aspects of this organization until they are strong enough to stand on their own abilities as a formidable underboss. [Answer] Rarity. Not everyone has the potential for the occult; in fact, just finding an intern with any promise may take a few years. If your ritual takes five talented witches at a minimum, then a witch dying will be a serious blow to the coven unless they have backups, and by the time one has more than four backups, they'll probably have left to form their own coven (they wouldn't be in this business if they weren't a bit distrusting of larger groups and willing to tamper with things they don't fully understand). [Answer] A variant on the hierarchy idea. Casting spells is a dangerous task. The energy needed is unstable and can lash out in any direction, but it can especially backlash on the caster. So a witch needs other witches to focus the energy, as a supporting structure. The stronger the witch and the stronger the supporting witches are, the safer the spells are, the mightier the spells that can be cast. The lowest in the hierachy need to be trusted, so they don't turn against those above them. Otherwise casting spells can be life threatening for a witch. A goddess witch with the support of all lower witches can then safely perform godlike spells. [Answer] It would happen naturally. Coven members and apprentices require investment by the witch to teach them, or recursively from others the witch has taught. Coddler witches, those that don't cause their recruits to die en-mass, end up producing more witches per unit effort. Over time, the Brutal witches will end up being outnumbered by those that don't waste precious resources, unless they use those resources in turn by attacking the Coddler witches (or, at least their recruits). Coddler witches can have people die, but you aim to have people who (a) are cheap, and (b) are effective for their costs. Someone who has done 2 decades of abstract magic research isn't much more effective than a well fed peasant. ]
[Question] [ I'm working on a space-opera type setting for a story I'm writing, and while doing so I've been thinking about a question that has been bothering me for some time now. The protagonist of my story is a girl whose father died in an asteroid mining accident years ago. But since my setting takes place in a world with FTL travel, AI, a lot of standard scifi technological advancements, then it begs the questions why blue-collar jobs that require hard manual labour like construction, mining, cleaning etc would still be done by people instead of machines? Settings like Star wars gloss over this but I have a tendency to overthink issues and I want an answer to my question. [Answer] We need a better definition of "Blue-collar jobs" Jobs in construction, mining, cleaning are not as physically demanding today as they were in the past, and, with few exceptions, they can no longer be called "hard manual labour". However * this labor is still mostly manual; * it requires people to work in harsh environments and subjects them to various hazards; * it (usually) does not require college degree or long training; We can increase automation and increase productivity in many areas occupied today by blue-collar workers, but eliminating them entirely is not something that we have on horizon, not unless we are talking about highly futuristic settings. As of now (and in foreseeable future) humans are the best to pick up any new job or function, whether it's manual or non-manual. Later, automation can decrease job openings in this profession or eliminate it altogether - but that will come later. In a "realistic" Sci-Fi settings, some blue-collar jobs that we know will be non-existent - but then some new ones would come up. So none of the professions that you mentioned may exist in the future, but "blue collar jobs" in general should stay with us for quite some time. [Answer] I don't follow why "died in an asteroid mining accident" equates to his having a blue-collar job or manual job. Why wouldn't her father have degrees in engineering, chemistry, metallurgy, astrophysics, electronics, and several other future specialties (cyberpsychometrics) - earned over the first 50 years of his much-extended lifespan, which is why he was entrusted by his employer to design, deploy and single-handedly operate a multi-billion dollar (in current $'s) fusion-powered robotically staffed extraction, refining, and mass-driver launching system as it digested a 2-km diameter metal-rich asteroid. Too bad he liked to go out and watch the big lasers dicing up those kiloton 'bricks', and caught a micrometeoroid that snuck past the defensive lasers but was big enough to kill a man in a short-exposure space suit, when it hit at just the right - or rather wrong - angle. OTOH, in his era, that probably was considered a blue-collar job. [Answer] Until you get to true Sapient Synthetic People levels of AI (a hard feat in and of itself), all decision making by an AI boils down to 'if [this criteria] then [that response] otherwise, if [some other criteria]...' Now, this is fine for the majority of cases where values are within expected parameters, but eventually the cost-benefit of coding for less and less likely events is better served by defaulting to "go ask your human overseer". This thus requires a knowledgeable human to be on site to handle these edge cases, which puts them at risk. Similarly, if a robot is damaged, there's only so much an automated system can do to repair it, before they have to default to a human mechanic. And what if the analysis AI itself is damaged? Who watches the watcher in this case? Again, a human is required. Thus, your unfortunate father could have easily been working with mining robots on this asteroid, and one malfunctioned, causing his death. [Answer] 1. It saves money For what ever reason to pay someone to do theses job is cheaper then to build and maintain expensive and fance thinking machines. 2. It is illegal. Laws prevent or limit the use of thinking machines. 3. It social taboo It maybe legal but socity looks down on companies that replace human jobs with machines. Saw humans are employed for public relations reasons. [Answer] Most of the hard work in mining is already done by by machines today, and when we extrapolate the trend to space, then [we can safely assume](https://worldbuilding.stackexchange.com/questions/34360/who-should-mine-the-asteroids-humans-or-robots) that mines in the far future will require even less people. But that does not mean that a mining operation can be 100% automatized. What if a robot somewhere in the mine suddenly stops working? Then a human has to find out what's wrong. Which might require to get into the mine, find the malfunctioning robot, diagnose the problem and decide how to fix it. This might be rather dangerous indeed. For example if that robot suddenly starts working again with the technicians hand in it. Or if the cave-in which took out the robot destabilized the mine shaft and causes another collapse. Or if the robot unearthed some weird ancient alien stuff which should have better been left undisturbed. [Answer] Money. It can be as simple as that, if you like. The Culture novels of Iain M. Banks, for example, deal with a society that has moved on from money; since they have mastered energy production they can fabricate anything they want and there are no shortages and nothing is ever unavailable. Money has no place in a society like that as almost everything is free, therefore there's no such thing as an "expensive" mining robot - you can have as many (and as sophisticated) as you need. People in that society only work if they really want to - if they have a special interest, say. If your society hasn't gone quite that far, manufactured things will still have a cash value and people will still need to earn money to buy them - you can easily parlay that into it being much cheaper to have humans mining asteroids with support from a few, very expensive and hard-to-replace, semi-independent machines. If you look at the stratification of society today, here and now, it shouldn't be too hard to just push that forward in time and see that there will always be blue-collar jobs while money is a thing and the profit motive drives business. Just assume a good mining bot costs 1,000,000 whatevers and a human miner/maintenance man costs 25,000 whatevers a year (for comparison, in the UK right now, the average annual wage is about GBP 26,000 and there are cars that cost well over GBP 1,000,000). Basically, tomorrow is just like today, only more polarized and potentially even harder going for people in manual work. FTL travel is also extremely expensive, and the ships cost billions so if the mining budget can be shaved by having people (who, to be frank, are an ever-expanding, replaceable resource), then the question is why wouldn't the big corporations stick with cheap wetware for the hard graft and supplement their bottom line by deploying just a few expensive machines to help out? [Answer] It's your world. You can write whatever you want into it. The more advanced technologies might be distributed very unevenly. Some backwater planetary system might still have far more demand for human, manual labor than the richer and more cosmopolitan worlds. The reasons for these disparities might be economic, financial, political, or even religious or rooted in racism. When I say economic or financial, I mean that the constraints might be imposed by the environment and, ultimately physics, the technology depends on some mineral or compound or substance which is infeasible to synthesize in quantities to meet the demand (antimatter, dilithium crystals, unobtainium, phlogiston). Those are economic constraints. Or it could be that the technology is locked up in licensing or intellectual property constraints which effectively deny the associated benefits to whole star systems (copyright EULA terms on the positronic brain AIs which effectively impossible to clone and too expensive for fringe worlds. It's your world. You need to decide a bit more about it than you reveal to your audience. But lots of stuff can be left unknown and waved away with "it's complicated." (Then have the action and the more immediate motivations of your character move the story along without fixating on minutiae). In fact the entire genre of space opera is characterized by epic character facing epic challenges. The environment, the stage, is stylized with trappings of science and technology. Usually, and especially for space opera, Clarke's Law applies: to wit, "any sufficiently advanced technology is indistinguishable from magic." [Answer] Several answers have provided hints as to how your protagonist's dad could die in an asteroid mining accident without doing what we would consider a blue-collar job, today. But if it is also important to you that your protagonist comes from a working-class home, i.e. if the socioeconomic status is relevant, then we need a different approach and a different question: Why is there still a working class in a sci-fi setting? This is not the question you asked, and maybe not one you want an answer to, so I'm not going to try to give a detailed answer (but if anyone wants to do that, feel free to edit), but in short: 1. The reasons why we would have a working class in the future could be quite similar to the reasons we still have one today. With all the technological progress we have made, it would be quite feasible to work as little as [six hours per week](https://www.independent.co.uk/news/business/six-hour-work-day-increases-productivity-so-will-britain-and-america-adopt-one-sweden-a7066961.html), but that's not what's happening for most of us. 2. Now, from a [Marxian](https://en.wikipedia.org/wiki/Marxian_class_theory) point of view (which is strongly associated with the idea of a working class), the deciding factor is not how much or how hard you work, but whether or not you have ownership over the means of production (factories, machines, etc.), as opposed to only owning your own labor, which you then sell to someone else for wages. 3. Putting those two aspects together, it seems there are largely political/societal reasons for the continued existence of a working class even in the face of technological progress that could have abolished classes altogether. If, in your world, those factors remain, there is no reason why sci-fi technology should get rid of working-class homes for your protagonist to grow up in. [Answer] # Insurance. Your protagonist's dad was an insurance compliance officer. His and his colleagues' job was to generate reports and logs corraborating the mining swarm's reporting- impartial observers tasked with ensuring that the swarm acted according to good mining practice. Just the machine logs obviously cannot be trusted- the machines could be programmed to report "all is well" while in reality eschewing proper runoff capture to conserve fuel, in the process spewing tons and tons of micrometeorites at a nearby shipping lane etc. So, the liability and equipment insurance providers require that all excursions include multiple human observers to try to curtail this type of liability-causing behavior. Of course, this job is somewhat monotonous and hazardous, takes place outside the comforts of civilized society, and requires a long time commitment. So it seems to check a lot of the boxes for what we call blue-collar work, in the sense that well-paying but somewhat hazardous and dull work in a remote location, like for example oil-rig work, is decidedly blue-collar in our current time. [Answer] Culture could ensure it. A future religion or philosophy with 'dignity of labour' at the centre could encourage/require people to work manual labour. (Like in A Million Open Doors by Barnes where people replaced the more efficient robot to do their eight hours of labour) [Answer] Yes, but it isn't recognized by the majority of society. While the technology has long existed to automate every part of this, every several centuries the growth of the human population far outweighs the production capacity of the AI/robots and the tools that provide our wonderful human utopia. And so, while more machines can be built, it's a simple matter of economics. There are so many more people that by putting them to work in dangerous conditions, you not only have a cheaper resolution for the increased production, but in these conditions the human laborers can't reproduce, and many die. The AI figured this out a long time ago, and it is simply the most efficient method to ensure the continued, optimal growth of humanity, which is all it was programmed to do. So when the population reaches what the AI has internally dubbed 'the tipping point' a new disease in created, and it wipes out great swaths of humanity, but no one really dies of the disease. They're taken to hospitals and the friends and family are convinced they are dead - or entire social groups 'catch the disease' and are forced into slave labor together. The greater human society would never allow for this, but are entirely ignorant. In the worst case of 'the tipping point' an entire planet's population was 'wiped out by a vicious disease' - it only spread to about a quarter of the population on most other settled planets. Naturally, the AI has determined the value of people by the method's people themselves use, so the wealthiest, most well connected - the government officials that interact with the AI - the famous and those of generational wealth are not only never targeted, but they never know. As far as "all of humanity" is concerned, we live in a near perfect utopia, that only periodic pandemics affect in any significant way - for all technology, the AI assures us biology is still unbeatable - and anyone who might've known better died centuries ago. After all, who needs to intensively study biology living in a utopia? [Answer] There are a couple of possible reasons that I think easily clear the suspension of disbelief in space opera bar. For instance: Brains Have Been Very Extensively Field Tested Brains have been around for at least 550 million years on Earth (and maybe far longer on some other worlds in your universe). Even if your world has developed superhuman AI, it is certainly believable that research has not managed to replicate every trick that is implemented in the vertebrate brain. As a consequence, you could for instance posit that superhuman AIs in your world are, for all their greatness, still vulnerable to variants of [adversarial examples](https://en.wikipedia.org/wiki/Adversarial_machine_learning#Adversarial_examples). This could mean that human labour is very desirable for jobs that do not require superhuman intelligence but which do require commonsense reasoning robust against adversarially controlled input. For instance, say your empire is strip mining some planets under its control for valuable rare minerals in order to meet its quarterly Death Star production targets. It would be very unfortunate if rebels or environmental activists managed to make your strip mining robots misclassify improvised explosive devices as chunks of valuable ore. However, if you hire a human, your operation gains an additional layer of spoofing security and your dominion over the galaxy is assured! Note that in that kind of setting, AIs may find it useful to optimize biological brains and bodies in such ways as maximize their ability to take advantage of specific biological capabilities while minimizing creation and upkeep costs. In that sense, the degree to which your workers end up being recognizably human may vary. History Shows That Developing AI Is Not A Good Idea If your setting has FTL travel, the ruins of ancient civilizations that did not successfully pass some existential risk filter may serve as reminders that the future is uncertain and that it is often unwise to overstep one's station. For instance, in the spirit of Alastair Reynold's Revelation Space series, it may turn out that some Elder Civilization is for some reason destroying everyone who develops general artificial intelligence. In such a setting, some civilizations (or enterprises) may continually test out the boundaries, but humans (and maybe aliens) would stay gainfully employed for as long as the Elders remained active. Humans Are Competitive for Low-Skilled Labour It might simply be that it is difficult to improve very much upon the price-performance ratio of humans for some types of relatively unskilled work (i.e. work that does not require superhuman intelligence), especially given that humans will reproduce and raise more humans for free. In that setting, your galactic empire will entrust highly complex technical work to AIs (say, the design of secure battle station exhaust ports), but simply has no reason to completely automatize the myriad of menial tasks that have always been done by manual labour and that can be executed satisfactorily in that way (for instance, the planet-side part of mining operations on planets not yet uninhabitable). [Answer] In some not-too-near future there will not only be no blue-collar workers; there will not be any white-collar workers either. There will be almost no traditional gainful employment whatsoever because AI and robots will be so much better at almost all professions you can list, probably including research and science. The only pockets left where humans still are working professionally will be human-to-human interaction which per definition cannot be automated: Some education, and some care, e.g. for the elderly, even though much of both — mainly the routine parts — will also be done by machines. Humans will only do what they want to do: Produce art, pursue hobbies, play, travel. It is entirely possible that some people would travel to dangerous places, as a hobby. In a scientifically advanced society people will be almost immortal; that will probably affect their stance towards risk-taking. Compare that to the elimination of ever more remote risks already today: Every toddler has a 5 point belt in their buggy. Because they simply don't die from other reasons any longer the remote possibility of a buggy accident has become t op risk to toddlers. Virtually immortal people will likely be extremely risk-averse. Driving their own cars will be the equivalent to free solo climbing today: "But if you make a single mistake you die! That's insane!" On the other hand there are free climbers today, or the Russian kids riding on the roofs of trains for fun, inches from the high-voltage lines. Such fads will likely be there even among immortals, and traveling to an asteroid mine could be a thing you can book in a travel agency, even though most people would shake their heads in astonishment over such foolishness. [Answer] Overall you have it backward. Most of the white collar office work will be automated. Blue collar work in running/repairing the machinery will be much later in the automation cycle. The jobs left will be fixing/operating machines, and dealing with people. Story time: I run a tree farm. Not a big one. We do about a quarter mill of trees per year. I could buy a potting machine that can pot 400 two gallon trees per hour. It takes 4 people to operate. I have to change pot holders if I want to switch from using a Listo pot to a Nursery Supply pot. The machine costs 60 grand, and uses only standard peat and bark mix soils with a density of about 0.3. I have to run it a month a year to break even. Instead I use high school kids. 4 high school kids can do about 150 pots an hour. A verbal command changes the watering, fertilizing, and multching system. When I don't have trees to pot, I can put them to work weeding. Or emptying dead pots. Or sorting pots. Try doing this with a potting machine. The human hand is a great general purpose tool, and it's a meta tool too. [Answer] If your word is mostly AM it is probable that blue collar job still exist. heavy machinery will do a lot of the job, but it's probable than this kind of job will still exist for several reason depending on your world rule Manual labor (even if assisted by machine) could have several advantage in comparaison of the one of machine: -high adaptability. human can do a lot of different thing where as for a machine it might be extremly hard to do something it is not thinked for: from their tool to the IA in them their specialised tool and there is no reason to give even to an extremly advanced robotic arm the ability to do everything. -much less constrained by their environement. a bit like above, but it's more about where the work happen. it's not unthinkable to have some mining/space operation where machine are still unable to effienctly evoluate in, where as a living being with the proper equipement would be more efficient. -artisanal added value: especiallly in a universe where the machine do more and more the feel of something that was made by another living being would be extremly valuable, so it's not unthinkable it would be profitable for compagny to have large scale operation to make handmade item to "sell" some autenticity to richer population. -replacability. it's cynical, but especially in a space opera, the number of living being if of the chart so having population entierlyo devoted to cheap manual labor could be cheaper than maintaining huge machine that cost a lot to replace when something goes wrong. -qualified blue collar: it's a shift we are seeing more and more today, but even blue collar job start to ask for qualification. so it could be plausible that if the machine do most if not all the production you still need a laborforce who will be able to keep the machine running. [Answer] Ethics One thing AI is unlikely to ever outperform humans, is ethics. If anything, because ethics is something volatile that humans agree and modify over time based on their own perception of humankind. When a given AI system is forced to balance certain outcomes, it may make a purely optimal decision, minimizing harm or maximizing benefit. Humans, on the other hand, can see beyond such "value function", and consider other particularities such as fairness, empathy and emotional well-being. This is why multiple-choice exams are not that frequent. [Answer] Late-stage capitalism. In our own world we've already seen how capitalism, instead of lifting all boats, invariably ends up creating different classes of wealth. It also tends to disproportionately concentrate large amounts of wealth in the hands of very few people. The only thing that prevents blue-collar workers from being exploited even more are laws protecting them. Take those laws away and you have a dystopia where such protection laws don't exist, and thus employers have zero incentive to use more efficient labour (robots) because less efficient labour (humans) is cheaper and easily available. The "working class" in this scenario has almost no rights and are essentially wage-slaves. [Answer] ### Advanced aliens have manipulated what technologies society has developed. So, the Lensman series was a series of Pulp scifi novels that involved the tituar Lensman (psychic, uncorruptable space police) flying around on planet-destroying spaceships that used slide rules and vacuum tube computers for navigation. Some time later, a supplement for the roleplaying game GURPS was released for playing games in this series' setting, and one of the things proposed by it was that the advanced, benevolent psychic aliens who founded the Lensmen were responsible for manipulating human society's technological development to prevent the invention of the semiconductor, since advanced computers would cause a psychological reliance on them that would inhibit the development of psychic powers. It's possible that your setting might have something similar going on, that prevented the development of the sort of technologies that would allow for the sort of automation that you'd want to prevent happening in your setting. [Answer] There is a bell-curve when it comes to automation, where extremely wealthy and advanced societies actually start reducing automation in some areas. Having hand-made things is a major status symbol already today. Look at the [chess sets for the World Chess Championship](https://www.youtube.com/watch?v=-Tg9xiJ6D6k) for an example. Woodworkers train for years to hand-carve the pieces. FIDE could easily just go to Wal-Mart and buy a few dozen injection molded plastic sets, but that wouldn't be prestigious enough. So maybe the wealthy elite in your setting want hand-made luxuries, some of which can be dangerous to produce. [Answer] I can imagine a world where Luddite Workers forming a kind of trade union where they destroy several robots to maintain a workforce. Alternatively it could be a populist leader that is "andoridist" where human like androids are treated like minority groups have at different points in history and hence are a low priority for work. Alternatively there is an agreement that machines should not be fully automated with fear that they may turn against people and so every group of robots would require a master to oversee their actions. Another idea is that perhaps there was a population explosion and a material shortage so workers are a more available resource and would be needed to extract materials to make more robots. Or quite simply, as others have noted, workers might be cheaper than robots so there was a shift from automation to manual labour. This actually has precedence in today's world. Some manufacturing and laborious work has shifted away from automation to cheap overseas labour as it costs less than installing, operating and maintaining machinery. Yet another idea is that people with a sense of adventure might want to explore new lands in spite of the risks. There is no shortage of people wanting to join a potential future mission to Mars even though it has not been done and so could be very risky. Or many explorers in the past sailed into the unknown in spite of the dangers of the sea. Finally perhaps resources are very precious so there is a situation like the Gold Rush where people flock to new lands to get rich. ]
[Question] [ After reading [this thread from a bit under a year and a half ago](https://worldbuilding.stackexchange.com/questions/58333/how-to-fly-around-the-martian-thin-layer-of-sky-without-burning-holes-in-our-poc) about the most cost-effective means of travel on Mars, where one of the answers mentions rail as the best option, I started wondering: since rail travel depends on the friction between the wheels and the rails, which is proportional to the pressure holding the two together, which is proportional to the weight on the wheels, which would be much less on a low-gravity world than on Earth, might this make lighter rail vehicles, such as trams, unworkable or impractical on low-gravity worlds? Some problems I thought of: * The reduced weight on the wheels would weaken the adhesion between them and the track, making them far more prone to wheelslip than Earthbound trams (especially when accelerating quickly from a dead stop or braking hard from [relatively] high speeds, as the low gravity would decrease the weight on the wheels, but not the tram's momentum, as its mass would remain the same). This could be solved or mitigated by: 1. having wheel bogies that wrapped around the track (like with rollercoaster trains), which would greatly complicate switching (ordinary switches would almost certainly not do the job; [transfer table](https://en.wikipedia.org/wiki/Transfer_table)s or something about as complicated would be required, which would take up much more space than an ordinary switch and be more complicated to build, operate, and maintain) and make a dedicated right-of-way an absolute requirement (trying to maintain the required clearance under and to the sides of the track would be an absolute nightmare in street-running situations, and would be a headache even for the very short stretches required for grade crossings); 2. using a rack-railway system, which would also complicate switching, to a greater or lesser degree (depending on the precise rack system chosen), and might (again, depending on the precise system used) also make street-running difficult or impossible; 3. using some method of moving the trams not dependent on wheel-on-rail friction, such as cables (would pose difficulties with switching, would make it difficult or impossible to cross moveable bridges or anything else that produced intermittent discontinuities in the track, would be prone to sudden, large-scale disruptions of service due to cable breakages), linear motors (as in many maglev designs, but this method of propulsion does not require that the vehicle being propelled be a maglev; would likely require a completely enclosed ROW to prevent or mitigate the serious issues that would otherwise result from the powerful magnetic fields required, which would make grade crossings flat-out impossible and could cause difficulties with switching), or hyperloop-style air propulsion (would also require a completely-enclosed ROW [although this time because it would be to increase efficiency, requiring far less air to be moved than with an open ROW], creating the same problems as the previous option). * The reduced weight on the wheels would also make the trams more prone to derailment, by making it easier for the wheels to ride up and over the rails; this could be reduced or eliminated by using wraparound wheel bogies or completely enclosing the ROW (each of which would have their own problems, as described above), or by making the trams much heavier (which would greatly degrade the already-subpar - see above - starting and stopping distances, as well as considerably increasing energy use by the trams). So, would low gravity make trams and other (relatively) lightweight rail vehicles unworkable or impractical? [Answer] Simply solved. Keep in mind railroads already have this problem, because steel-on-steel adhesion is quite poor, with only about 40% adhesion even possible, with sand application. ## Track brakes Track brakes are attached to the bogey (truck) and contain electromagments. They are positioned above the railhead, and fill most of the distance between the two axles. They are tied to the suspension so they can ride quite close to the rail. Track brakes are able to be run by batteries. [![enter image description here](https://i.stack.imgur.com/UcXV9.jpg)](https://i.stack.imgur.com/UcXV9.jpg) [\](https://commons.wikimedia.org/wiki/File:Charleroi_BN_LRV_electromagnetic_track_brakes.jpg) Now there are two modes to operate a track brake. First, line it with brake pads and give it free motion downward* to clamp onto and slide along the rail. This is the normal operation method today. Second, "pin" it so it does not have free motion and cannot contact the rail. Now it is magnetically pulling the wheels down upon the rail, increasing adhesion on the wheels. I'm not aware of this mode being in practical use today. ## Bigger flanges Look at tram flanges -- they are very short compared to railroad flanges, because of the way street railway rail is built. (also a tram derailing is not a big deal). Use railroad flanges on your trams. That was easy. ## Don't forget linear induction motors This isn't maglev\\. Linear-induction is simply the common AC induction motor "unwound" and laid flat" - the copper-coil stator on the bottom of the railcar, the aluminum squirrel-cage "rotor" laid down between the rails. An example is the [UTDC system](https://en.wikipedia.org/wiki/Bombardier_Innovia_Metro) used by the Detroit People Mover and parts of other metro systems. This linear-induction thrust happens independent from any wheel/rail adhesion. It isn't optimized to pull the train car downward toward the track, but it could be. --- \\ Maglev: another technology that moots the gravity issue, because the car floats on a cushion of money. Seriously, cost is the problem: the technical challenges result in very high cost, at least as compared to bulletproof off-the-shelf old railroad, which can get within 5% of maglev's speed. As such, unless cost is no object, I tend to write off maglev. [Answer] Use [Maglev](https://en.wikipedia.org/wiki/Maglev) trams and trains. They are free from the issues that wheeled transport would have. Increased braking distances for trains and cars on Mars would be a literal killer. [Answer] Rollercoasters solve this problem with three wheels around the rail. This makes switches larger and more expensive, so it would make rail network designers attempt to avoid placing them, and instead build a tighter mesh near city centers rather than joining all the suburban lines to a large trunk, and city-to-city connections would likely get dedicated platforms. [Answer] You're right about friction being required for wheel based motion; this is why car tyres are made out of rubber. That said, ever noticed how certain drag cars, bikes, et al can do burn outs? Friction is necessary for forward movement, but to facilitate forward movement, it only has to be stronger than the forward force of the vehicle. On earth right now, a light vehicle by comparison to the the forward driving force will cause wheels to spin because gravity (via the weight of the vehicle) is outweighed by the forward force. This is also why we talk about a vehicles power to weight ratio. Just looking at how bikes and drag cars do burnouts though, you'll notice that they way they do that is to apply massive amounts of acceleration in a very short time. This introduces a massive amount of forward momentum (force) that overwhelms the ability of the tyres to grip the road. If you accelerate slowly, you don't overwhelm the friction in the tyres and you can get up to quite impressive speeds. On Mars, the lower gravity will mean you have 3 options to ensure that you get forward movement; 1) Make the carriages heavier 2) Increase the friction between the wheels and the rails 3) Introduce acceleration and deceleration MUCH more gently Ironically, the simplest of these might be option 2; the reason why we don't put rubber on train tracks or wheels is that the train is so heavy, the necessary friction is achieved metal on metal. BUT, on Mars, it may be as simple as making the tracks cog-rails, and the wheels cogs. This effectively greatly increases friction by putting most of the pressure of the wheel against the front of the cog rail tooth, and the rear of the train wheel tooth. Theoretically, you could put bands of rubber around the train wheel, but we don't do that on Earth because of the maintenance hassle (car wheels are MUCH easier to remove) and that wouldn't be likely to change on Mars. Of course, the other option is that you just load up the train. A train that weighs less can carry more mass to generate friction (but physics being what it is, this train will still take more energy to move). That said, the increase in energy required to move the increased mass may be counterbalanced by the lack of atmospheric resistance because Mars' atmosphere is less than 1% the thickness of Earth's. In any event, expect Martian trains to carry much more freight than Earth ones. Finally, you could just accelerate and decelerate between stations at a much more reduced level as we would on Earth. The good news is that you wouldn't need a very large engine anymore (power to weight ratios again) although it would mean that your train is going to be much slower in getting between short term stops. This is not an option for an inter-city train, but would make much better sense for a trans-continental equivalent on Mars. This last option has one flaw; the massive changes in altitude around Mars. Earth trains also struggle with this, which is why we make so many rail bridges and tunnels. Mars has much larger changes in altitude between places we'd actually want to go so this may be less of an option and a weak engined train is even less likely to be able to climb a (say) 5 degree incline for an extended period. So; I agree that rail is still the best option, but exotic wheel options are not necessarily required, and switching could still be preserved with minor modifications to the way train lines work (like light cogging on track and wheel). The one catch with such an option would be that the engineering of tracks and wheels would now have to be more precise and putting pennies or rocks on the tracks would now be more problematic, but that is perhaps commentary for another question. [Answer] Rack or Cog railways would not depend on gravity as much for their friction, and you could guarantee contact with between the cog and rack by having wheels above and below the rail. <https://en.wikipedia.org/wiki/Rack_railway> [Answer] consider Monorails. All the switching problems were solved long ago, and the wheels are applied to all sides of the rail. In some designs the load bearing wheel is not the wheel providing thrust or braking, the side wheels (or a track brake does) that, which exist in opposing pairs so they are not affected by the reduced weight. [Answer] [![enter image description here](https://i.stack.imgur.com/MRmrH.png)](https://i.stack.imgur.com/MRmrH.png) It can have an inverse triangle shaped track. This allows rubber tires on top to carry the weight, and tires on the beveled sides to guide it. But much more, all the tires would have airbag suspensions, allowing the wheels to press on all three sides of the triangle in precisely controlled ways. While the top ones would bear the weight of the monorail, all three tires would also be opposing each other, effectively clamping the rail. These extra "opposition forces" create artificial downforce-on-rail that doesn't depend on the weak gravity. This extra adhesion is just as usable as gravity-derived adhesion. Better yet, monorails tend to use rubber tires on concrete rails, so adhesion is comparable to an automobile, at around 100% rather than the ~40% of steel-on-steel. It should be able to brake quite well, as much as two "gees" on Earth and quite a few local "gees" -- which may be too much for the safety and comfort of those acclimated to the weak gravity, especially if (like most trains) it doesn't have seat belts. Earth transit systems prefer to limit accel/decel to 4.5 mphps which equates to 2.0 m/s2 or about 0.2 gee. [Answer] Just to add my two cents here: less gravity would give some simplicity if compared with regular (Earth) trains/trams. 1. Number of axis. Talking about railroad, most likely you imagine a carriage as something with two bogies per carriage, two-axis each. This is done to decrease a pressure applied to rail. Lower gravity allows you to come back to one-axis bogies (two axis per carriage at all, as it was in XIX century) because you don't need to distribute that much pressure with multiple touch-points. 2. Carriage size. With less gravity, you can increase a carriage size thus efficiency (make it two-level, wider, longer etc.) having the same pressure on the rails. Even you can do it as a flex-jointed sections, one axis per section. And all this not about electric-magnetic field, just old good mechanics. With electricity involved, you can move far beyond this point. ]
[Question] [ Straight to the matter: is it possible that a faction in a science fiction world rises up while completely ignoring the concept of villages as a whole? Let me explain. While it's specific for my world, I guess it's applicable to many others: planets are colonized from a single site, with its initial population heavily relying on that single site. Usually these become cities and eventually capitals. And then they start spreading. But not anywhere, obviously. Depending on the faction itself, there are basic, as well as extra needs to be fulfilled. Is it a realistic scenario that, due to the large resource requirement, new settlements are always so large that they can be considered cities immediately, without ever going through the farm and/or village phases? Either way, what are the implicit "requirements" for such a "nation" to exist? I'd assume cultural reasons but I don't really understand, what villages tell about us as a nation. If that help narrowing the scope of the question, I primarily aim an approach from the so-called Western culture, so Europe and to an extent, the US. To help further narrowing the scope, by "village" I mean settlements with relatively small population that while provide basic infrastructure (e.g. clean water), lack many of the more advanced ones (e.g. sophisticated transportation like airplanes) and rely on proper cities for those. [Answer] > > Is it a realistic scenario that, due to the large resource requirement, new settlements are always so large that they can be considered cities immediately, without ever going through the farm and/or village phases? > > > There are two questions here: 1. Can we build a city from scratch? 2. Can we avoid villages? Let's take them one by one. # Can we build a city from scratch? Yes, and it makes perfect sense. See [Brasília](https://en.wikipedia.org/wiki/Bras%C3%ADlia#Background) - planning started in 1957, it was planned as a capital city, and resources were, just as you want, one of the major reason for this move. So this one is definitive yes. # Can we avoid villages? There is a saying "some villages are built only because you can't have any more fields without interruption". And that's exactly the case. If you have rich farmland, you do not want to burn dozens of square kilometers to raise a city, and then have people travel 10 hours to work every day. So this is tech level dependent. If your farms are autonomous and you can have a technician on his speeder visit farm 100km away in half an hour if needed, you can avoid having villages. You don't need them. If your farms are not that autonomous and need people every day, it all depends on the cost (monetary and time) of people traveling to work. The higher it is, the denser your villages will need to be placed. So this one is maybe. Note that there are another kinds of villages, but your nation can live without mining villages or gold gold seekers villages. Or artistic villages. It can't without food. This is the only function you can't ignore and can't easily replace. # Nation? Nation is not really universal, long time thing. There is no consensus if what we call nations even [really existed in medieval times](https://en.wikipedia.org/wiki/Nation#Medieval_nations). First thing that was for sure a nation [appeared around 16th century](https://en.wikipedia.org/wiki/Nation#Early_modern_nations). Before that? Cities and surrounding villages were bound together, because cities needed food and villagers needed protection and products from craftsmen. It was important who is your liege lord, of course, but that's about it. Forming of nations as we know them has a lot to do with communication and politics, and very little urbanization level, as far as we know. [Answer] An easy way to justify large cities-only settlements is to have specific requirements that can't be scaled down too easily. One example would be to need a domed environment, easier to maintain in large clusters and difficult for small detached locations. Another example is need of a perimeter confinement to keep out "unwanted guests" (e.g.: large dangerous animals). Yet another could be some chemical elaboration needed to sanitize water or to make the air breathable. Usually, such plants are very economic if large, while smaller plants, if available, are much more expensive. [Answer] # Absolutely. If you're colonizing a planet, it's taken you a long time to get to that planet. That means you've supported a large number of colonists through completely uninhabitable space for a significant amount of time. So if you you just land this ship on the planet, then it sounds like you've just made your own completely self sufficient city on that planet. If this happens more than once, you could even envision an entire nation starting like this. [Answer] If your planet's environment is not totally fitting to its occupant's needs, like humans on Mars as an example, then any settlement would require a very large physical plant to process and supply breathable air or other necessary environmental conditions. The machinery to supply the needed environment could easily benefit from economies of scale or have some minimum requirements (A fusion reactor can only be built so small). These environmental and economic conditions could make smaller settlements infeasible and larger city-sized developments a requirement to support any long-term habitation on the planet. [Answer] Actually, this is pretty easy. Establish sustainability protocols that colonies have to fulfil. So what's sustainability and why would that be a protocol? Well, perhaps overcrowding and squandering of resources where they came from has lead to this. Sustainable cities are concerned with: * reducing urban sprawl, so your city will be compact * increasing walkability * establishing areas completely devoted to nature and not allowed to be developed at all * around and in each city food is grown for that city specifically So you start with a full city and build that. Then the government sends out survey teams to scout locations ahead of time, building the initial infrastructure before population is permitted to move in. People in the old city can sign up for consideration, and specific housing ahead of time, and early sign ups will give them perks. They'll sign up for jobs as well, at the same time. The city will remain empty except for those building it or on maintenance, or the first farmers you will need, until the population sign ups reach a certain level. Also build an elevated train to take them from city A to city B. Determine who needs to be first in, and over the course of a few months, move them in. [Answer] ## On the other end of the scale Another way of not having villages is to have only isolated houses. I'll assume: * Your colons have efficient ways of communication, for instance improved Skype up to the point that you can’t notice that you’re not there in person. * The planet is (or seems) harmless, so your colons are not afraid to live in an isolated house * They have fast means of travel, so that they can go quickly to anywhere. Maybe even drones to send and get products. So, when a colon family arrives to the new planet, some authority assign land to it. The family goes there and build a house. The next colon will be given another land, some kilometres away, and so on. Once all the usable land are given, it’s time to start colonizing the next planet. If you need to buy something, just go online and buy it. Some drone will make a delivery. If you want to sell something, just do the same. You can work online as well, for instance answering questions on Stack (they pay you now). If you need to socialize, well just do it online or take your glider to the bbq party of your neighbour, few kilometres away. Basically: Transportation and communication made villages obsolete (and cities too). People enjoy living in the countryside, clean air, [little birds](https://outdoors.stackexchange.com/questions/8517/identify-this-bird-call), no [noisy neighbors](https://interpersonal.stackexchange.com/questions/9074/how-to-deal-with-a-noisy-neighbor-youre-on-friendly-terms-with). [Answer] Possible, but highly unlikely, at least if the world is Earthlike. (That is, not restricted to domed environments, &c.) First, your cities need a hinterland to support them - food, raw materials, &c. The people who work in these fields aren't going to want to commute long distances from a city; they'll want to live close to their work. They'll need some support - grocery stores &c - so those will cluster nearby, forming a village. Second, there are always (assuming your humans haven't been genetically modified or something) going to be people who just don't want to live in cities, and will avoid them unless driven by some necessity (e.g. jobs). These people will be the ones most likely to have joined in any colonizing venture, in order to escape an overcrowded Earth. Indeed, it's more likely for your colony to disperse into a large number of villages & small towns, rather than forming large cities. Finally, why do you think you need "proper" cities for airplanes? All you need is a short stretch of fairly level ground to land it on. Check out any number of airports in the western US, some of which are hundreds of miles from cities. (Smiley Creek in Idaho is a personal favorite.) [Answer] [Arcology](https://en.wikipedia.org/wiki/Arcology), one of the main reasons that villages exist, or existed, was travel times to farming areas; you couldn't farm it if you could get there and home without losing too much of your day. An arcology integrates farming, industrial and living spaces within a single cohesive space. My feeling/opinion is that once established an arcology wouldn't spawn even suburbs so much as it would simply add full-function neighbourhoods as needed, either vertically or laterally; once you establish an arcology the only other places you need outside them are mining colonies for raw minerals and vacation spots for those who want to "get away". [Answer] One solution would be for the population to be primarily nomadic, but with reasons for specific locations to be highly populated - such as having large, localised, mineral/metal deposits which require lots of people and infrastructure to process. So, you start off with everyone nomadic, following animals on migratory routes et cetera, and then one 'tribe' discovers large seams of iron and copper and coal in close proximity. They settle down and set up mines and forges, and start trading metal tools for animal products from nomads. If the mineral wealth and demand was high enough, you could rapidly expand past the village stage into a town or city. Essentially you would have nomadic tribes/nations with a couple of 'hub' cities for items that were hard to acquire/produce on the move. Farming would develop after the city grew to a point where trading no longer provided enough food, instead of the farming driving the development of the village. Once the concept became ingrained, locations for new cities would be selected specifically for large-scale industrialisation, and the idea of anything as small as a village would seem alien. ]
[Question] [ Imagine a world of anthropomorphic animals (if you're thinking of [Zootopia](https://en.wikipedia.org/wiki/Zootopia), that's a reasonable starting point). People in this world have a lot in common with humans ‚Äî opposable thumbs, language, the ability to walk on two legs, etc. ‚Äî but also retain some characteristics of their bestial cousins. For the most part, physical violence among unrelated people is frowned upon. (However, there are notable exceptions; gatherings of male bovines and/or cervines at "certain times of the year", for example.) What happens among family and close friends is a little different, however. Equines and suines are known to nip at each other, and canines are especially notorious for "roughhousing". Of course, the opposite is also true. What type(s) of people would find this sort of thing most abhorrent? Answers should be based on the behavior of real animals, and should be limited to land mammals. (No whales, seals, manatees, etc... or bats¬π.) Also, there are no humans in this world, though there are other primates. (¬π There are no bat-people in this world. Unlike Zootopia, people have a much more physically-plausible minimum size, which means bat-people wouldn't realistically be able to fly, and I don't want people running around with unusable wings.) --- To put this in more human terms... some humans consider a certain amount of friendly physical contact perfectly normal; slapping a friend on the back, or "play punching", or giving your younger brother a "[noogie](https://en.wiktionary.org/wiki/noogie)". Canines would consider this sort of behavior extremely normal, if not "tame". I'm looking for (a) species that isn't/aren't necessarily opposed to any touching, but would be appalled by anything that might be construed as violent physical contact, such as the preceding examples. OTOH, species with a near-pathological aversion to any physical contact are okay too. (And I mean any. One that hates being hugged, but likes friendly scratches or mutual grooming doesn't qualify for 'hates any touching'.) [Answer] The hedgehog: [![enter image description here](https://i.stack.imgur.com/tUVZOm.jpg)](https://i.stack.imgur.com/tUVZOm.jpg) Some mammals respond to threats with aggression. Carnivores have effective weaponary for violence. Many herbivores have learned that the best defence is a good offence and many will fight over mates. But there are some who respond defensively. Hedgehogs do. They have a passive and effective defensive system. They are not build to fight nor to flee, but to curl up and let their spines do their job. They don't have powerful limbs to claw, and their teeth are sharp, but small. Moreover, unlike porcupines, their spines are not detachable, so do no lasting damage to one who investigates too closely. Their mating fights are at most "a bit of argy-bargy" with no teeth of claws engaged. <https://www.youtube.com/watch?v=3gOYh54Axqg> When the danger passes they uncurl and go about their business. They are insectivores that eat a lot of slugs, but there [Slugs aren't people](https://tvtropes.org/pmwiki/pmwiki.php/Main/NoCartoonFish) and so they don't count. The anthropomorphic form abhors violence, because its instinctive reaction is to defend passively rather than to hit back. The hedgehog doesn't cast the first stone. They are phlegmatic and stoical. The same can apply to African spiny tenrecs, the American armadillos and the monotreme echidna. This last one also has tiny teeth, reducing further its ability for violence (unless you are an ant) [Answer] Possibly - the capybara [![enter image description here](https://i.stack.imgur.com/H3Mt8.jpg)](https://i.stack.imgur.com/H3Mt8.jpg) Capybaras are somewhat known for being extremely relaxed around other animals and they are also quite social. They share their natural habitat with many other species and with some they have developed a natural symbiotic relation (with birds, for example). They also give an alarm when sensing a predator, which others around can benefit with. On the other hand, for reasons unknown to me, they also seem pretty chill with predators such as caimans. Quick googling will show you a lot pictures of capybaras hanging out with other animals. It is worth noting though that violence is quite common in nature (duh), so even capybaras are known to bite when threatened. [Answer] # The Sloth, of course. The concept of ANY energetic physical movement, much less that directed to injury, is anathema to their very way of life. It is rumored that they redirect the usual instincts for physical violence into political intrigue, but no-one has waited around long enough to verify this as yet. It can be hard to tell by body language alone. Image of a Sloth taking a noon Siesta: [![enter image description here](https://i.stack.imgur.com/GKZRFm.jpg)](https://i.stack.imgur.com/GKZRFm.jpg) VIDEO of a Sloth in !!!Fighting Frenzy!!! [![enter image description here](https://i.stack.imgur.com/GKZRFm.jpg)](https://i.stack.imgur.com/GKZRFm.jpg) Image of Sloth planning World Domination: [![enter image description here](https://i.stack.imgur.com/GKZRFm.jpg)](https://i.stack.imgur.com/GKZRFm.jpg) [Answer] Scientists have studied the frequency of aggression in mammals in several studies. [This study](https://www.nature.com/articles/nature19758) investigates the roots of lethal violence across Mammalia. However, this study is only based on field reports of positive confirmation that animals engage in lethal violence, which can be seen in how primates appear hyper-aggressive. Primate are hyper-aggressive, but they're also highly popular subjects of study and so their behavior has been heavily documented compared to something like a cricetid rodent or opossum for which few studies of behavior are made. This study also does not count the frequency of non-lethal violence and appears to be missing several taxa (it shows squirrels and opossums as violence-free when most field workers on opossums and squirrels will tell you how they will regularly kill each other when they have the chance). And groups that don't have a lot of killing still fight each other, like rabbits and kangaroos. Also an important thing to mention is that bonobos, despite their stereotypical depiction as peace-loving, are *not* an example of a mammal that abhors physical violence. Bonobos are actually more violent than humans, it's just that they're less violent than hyper-aggressive chimpanzees. [Humans are actually pretty bog-average in terms of aggression for a primate](https://www.theatlantic.com/science/archive/2016/09/humans-are-unusually-violent-mammals-but-averagely-violent-primates/501935/). My guess, the mammal that would most abhor physical violence would be something like an opossum. Note, this does not mean non-violent, just avoiding physical violence. Opossums hate to be around other members of their kind except when they want to mate, and if they hate being around each other, it reduces the chance for physical violence. [Take a look at the chart showing the frequency of aggression again](https://www.nature.com/articles/nature19758/figures/1). Look where the highest rates of intraspecific killings are: Primates, colonial ground squirrels, elephants, pack-hunting canids, social mongooses, and colony-living pinnipeds. Notice a pattern? Increased violence appears to be correlated with sociality. This isn't me just idly speculating here, [it's what other scientists have suggested drives the evolution of aggressiveness](https://www.theatlantic.com/science/archive/2016/09/humans-are-unusually-violent-mammals-but-averagely-violent-primates/501935/). The violence is literally inherent in the system. Possibly some island species might be less aggressive. Increased docility has been suggested to be selected for in island environments because food and space is so limited and there are fewer predators. However, it is not clear if this is always the case. For example, Galapagos fur seals, which are well known for their naive, friendly, inquisitive behavior towards humans, still fight violently among each other in disputes. [Mother seals have been known to kill their own offspring if an older sibling harasses their younger one too much.](https://link.springer.com/article/10.1007/s00265-007-0423-1) *tl;dr: I would say opossum. But in this case you would get a violent reaction to physical contact at all* [Answer] # Prairie Vole My answer, after about half an hour of poking around the Internet, is the prairie vole. I went looking for species that do male courtship displays as their primary mating ritual. Why? Because every species that does combat or dominance displays for mating rights is automatically less likely to avoid violence -- there's at least one arena where violence is fundamental to their nature. Female courtship displays are often contested by multiple males fighting it out. I found [a seemingly trustworthy website](https://dickinsoncountyconservationboard.com/2019/02/11/10-animal-courtship-behaviors/) that described the prairie vole: > > 1. Prairie voles > Prairie voles are almost the epitome of a happy, healthy animal relationship. The creatures, about the size of a hamster, only live one-two years, but they are monogamous during that time. Once they meet a member of the opposite sex, pheromones help them to ready for mating. After mating, they show love by huddling together and even have been seen breathing in unison, and studies have even shown they give "hugs and kisses" when one's partner is stressed. > > > Trying to confirm that citation lead me to a bunch of research articles about prairie voles and oxytocin, for example, [this one from the journal Nature](https://www.nature.com/news/gene-switches-make-prairie-voles-fall-in-love-1.13112#:%7E:text=Monogamous%20prairie%20voles%20are%20known,behaviour%20of%20their%20prairie%20cousins.). It seems that their easy-going nature and strong pair-bonding attracted the attention of many researchers who are investigating how brain chemistry relates to social relations. Most other species I could find that do courtship displays were birds (i.e., not mammals) or where female does display with the males fighting afterward. [![two prairie voles](https://i.stack.imgur.com/YNuHm.jpg)](https://i.stack.imgur.com/YNuHm.jpg) [Answer] I think the best candidate for this would be the Naked Mole-rat. They are classified as eusocial creatures, which means that they behave as a collective to support a single reproducing female rather than reproducing individually, similar to many bee and wasp species. They are the only mammals that behave in this way which makes them uniquely qualified in their non-violence. Their social structure means that there is no incentive to fight within the colony. There is no mate competition because there is only one reproducing female (the "queen"), and only a few reproducing males who are physiologically distinct from non-reproducing members. The only individuals who leave the colony are called dispersers. They are also physiologically distinct from non-dispersers and they leave to join other colonies in order to prevent too much inbreeding. They leave voluntarily and peacefully, so there is also no violence associated with this behavior. There is one significant exception to their non-violence, which is when it comes time to replace a queen. When a colony lacks a queen a number of other females will go through rapid sexual maturation and then violent competition until one of them emerges as the new queen. This could actually be interesting from a story telling perspective, a totally peaceful and cooperative species that occasionally goes through a period of serious violence before returning to communal cooperation. Perhaps they are secretive or ashamed of that behavior and never show or reveal it to other species, or perhaps they are unashamed of these events and see these events as unfortunate but necessary for the good of the colony. [Answer] Bonobos, unlike common chimps, are matriarchal and non-violent, at least within troops. They can be described as randy little buggers, as they use sex to reduce social tensions. They do eat meat, including lower primates, but this is a small part of their diet. [Answer] < :-) > Without a doubt it's the Honey Badger. They can't stand violence from ANYTHING. If a Honey Badger meets something that's violent, might be violent or can be suspected of thinking that violence may be a good idea it immediately uses all possible means to eliminate the violence source. If this is not possible (which is usually not the case) then it will do its best to drive off and discourage said putative violence monger. It usually works. A lion will usually think thrice before taking on a honey badger. Not that it has much choice. If a lion encounters a honey badger it may consider itself taken-on. You'd have to be crazy to be violent around a honey badger. * Not only is its skin tough, it's loose enough that a honey badger can turn around in it and bite its attacker. And speaking of bites, the honey badger can survive the bites of some very dangerous creatures. They eat scorpions and snakes, and they have an unusually strong immunity to venom. I was going to say that a Cape Buffalo abhors violence almost as much as a honey badger, but I now read that Cape Buffalos have been found which have been killed by Honey Badgers - so I guess a HB hates violence more. ]
[Question] [ I am developing a world were modern firearms are introduced into a medieval setting (I realize that this has been done since Mark Twain's A Connecticut Yankee in King Arthur's Court). I'm working on how my world will react to the introduction of such weapons. Given: * 14th Century Europe (if a specific location is required, use France). * A knight wearing common plate mail of the time. * An M1911 pistol using a .45 ACP round. Question: What 14th century technology could be used to protect the knight from the M1911 pistol while leaving the knight able to walk, fight, and ride a horse? [Answer] 1. Medieval armor was intended to offer almost full protection against bladed weapons, partial protection against lances, arrows and cross bow bolts, and a little bit of protection against blunt force weapons. It didn't do any good against heavy projectiles, against cannon or against direct hits by arquebus balls. Most types of modern body armor, such as those used by police, offer protection against light bullets travelling at great speed, but are useless against bladed weapons. Some types of modern body armor, mostly used by the military, offer a certain degree of protection against bladed weapons, but far less than medieval armor. 2. Medieval armor would be essentialy useless against a modern high-power pistol bullet. Some kinds of multilayered textile / leather medieval body armor would offer a certain degree of protection against small caliber anemic pistol bullets. 3. Medieval technology does not have to do anything against pistol bullets, because pistols are useless in battle. * Consider a serious medieval force, such as [Prince Edward's at Poitiers](https://en.wikipedia.org/wiki/Battle_of_Poitiers) fighting against and a force armed with modern pistols. Pistols are only useful at close range, say 25 meters of less; Prince Edward's longbowmen would have no trouble engaging the opposing force from way out of pistol range. (In the real battle they engaged the French infantry at a distance of more than 200 meters.) * A cavalry charge at full gallop covers about 350 to 400 meters per minute. Let's say that the opposing force featuring pistols can miraculously fire accurately at 50 meters: the charging horsemen will cross that range in 7 to 9 seconds. There is a reason that defending against heavy cavalry charges went from pikes directly to cannon and then machine guns; small arms just won't do. 4. Consider that the ratio between bullets fired in WW2 and enemies killed is somewhere between 5,000 and 50,000 to 1. And that was with rifles, not pistols, and soldiers did not wear any kind of body armor. The conclusion is that nobody would bother developing some sort of superarmor capable of "protecting the knight from the M1911 pistol while leaving the knight able to walk, fight, and ride a horse", because no such technology is needed. Indeed, in real history nobody bothered developing any kind of such technology for military use until very very recently. They might make some experiments, which will fail, but they would not spend large amounts of sweat and treasure seeking an elusive protection against such a small threat. [Answer] Back when firearms were introduced on the battlefield, armorers started to produce [musket-proofed](https://en.wikipedia.org/wiki/Proofing_(armour)) armor. This caused a little arms race, which the [musket](https://en.wikipedia.org/wiki/Musket#Heavy_arquebus) ultimately won, but better armor helped at first. * This [article](https://journals.lib.unb.ca/journalimages/MCR/1995/Vol_42/mcr42art09_ta2.jpg) has some penetration figures, with modern pistols and rifles for comparison. A modern pistol, with the smaller and lighter bullet, is comparable in penetration to a musket with somewhat higher energy. * Note that [.45 ACP](https://en.wikipedia.org/wiki/.45_ACP) might not be the best choice. [9×19mm](https://en.wikipedia.org/wiki/9%C3%9719mm_Parabellum) has nearly the same energy and a smaller cross-section. A [5.7mm pistol](https://en.wikipedia.org/wiki/FN_Five-seven) might be even better, but harder to get. * For that matter, look at a shotgun with slugs or a hunting rifle. [Answer] Most likely, yes .45 acp is a fairly low velocity round that doesn't need a huge amount of steel to stop it. Assuming hardened steel is being used for the armor. The breastplate is the toughest part of the armor and has a chance to deflect the round as well. Plus, once the threat is realized, they can just make thicker breastplates and be pretty certain a .45 acp won't penetrate. (Or carry a metal shield in addition to the armor) But don't just take my word for it, here's a video of someone shooting a reproduction helmet with a variety of guns, including .45acp, which does not go through. So stopping that particular round is, at the very least possible, but not guaranteed. That seems to be close to the upper limit for what it can take though. <https://www.youtube.com/watch?v=ygaSMeTh-f0> Rifles though, are pretty much guaranteed to penetrate, probably even through a shield as well. [Answer] Method 1: Presuming you have a 7 round Colt, the technology you need is 8 fellow knights on horseback armed with just about anything heavy. If these charge at the gunman, whilst it's theoretically possible that he/she could shoot sufficiently accurately and quickly to kill 7 of them from the point they get in range, I would doubt it is possible to reload to kill the final knight who can hit the (presumably unarmed) gunman with a handy sword. The knight you seek to protect can observe proceedings from a safe distance. If you have an 8 round Colt, add one more knight. Method 2. Put your knight in a castle. Pull up the drawbridge. Defend the castle with the normal 14th century accoutrements (e.g. boiling oil, archers). Sure it's possible one or two shots get through the castle's enormous wooden door but provided your knight doesn't stand near it, they are not going to get hurt. Your knight remains free to walk, fight, and ride a horse (inside the castle). Once the gunman has run out of ammunition, the knight can chase him down outside. [Answer] Jousting armor It protected it's wearer from the lanсe with total wight/energy of enemy, his armor, his horse combined. Total energy on the tip if the lance is at the order of sniper or antimaterial bullet - far greater than for pistol one. And this protection was quite reliable - deths were not that common on medieval joustings. Most clashes brought no harm for jousters. In XIV century jousting was quite a developed sport - so it was not hard to find gear, if you have money. I think we all know downsides of such protection: limited visibility, mobility (but still can walk and fight on foot), and astronomical price. But still - if some knight would like to punish some heretic with devil weapon - he have the way to protect himself from the projectiles of hell! [Answer] Depending on ammunition, you M1911 is not much different to a crossbow except that it does not hit as hard, or penetrate as well, and has shorter range. Better rate of fire, of course. Consider a mounted knight with a shield and lance charging at a man on foot with a .45. Which would you rather be? A cool-headed man with a .45 and good aim might win, especially if he was unsporting enough to shoot the horse. But I would not rate his chances that highly. [Answer] It would be a hard undertaking in the 14th century. Firearms were just introduced in Europe, and neither gunsmiths or armor makers had yet a lot of time to improve their work. As such a "bullet proof" armor did not yet exists. After the introduction of firearms in Europe, there was an arms race between gunsmiths, making ever more deadly guns, and armorers, making ever more bullet resistant armor. There is historical evidence, for knights on horseback using wheel lock pistols, but you had to shoot an armored knight point blank to stand a chance at beating a 15th century armor. Your best bet to beat a bullet is a layered defense; a cone shaped, hardened steel plate, over the regular steel breastplate. First layer makes the bullet tumble, second layer stops it. Something like that was used in WW1 to stop rifle bullets, so it should stop 45 ACP as well. 45 ACP has not that much penetrative power, so a regular plate armor, or even chainmail, might stop it, depending on range. They had the technology to produce hardened steel in the 14th century, but the art of armor making had yet to reach it's peak. So I imagine, the best armor makers of the time could come up with a suit of armor, that could beat a 1911, but it would be quite the feat. [Answer] [Silk has been shown to be a low-tech armoring material](https://culture.pl/en/article/the-monk-who-stopped-bullets-with-silk-inventing-the-bulletproof-vest). [Answer] <pedantic alert, but may impact your considerations of how you build your world> In our world, plate armor was anything but "common". It survives well and so it appears that everyone wore this, but the modern vision of fully-articulated armor of nearly all-metal construction was very rare and only affordable to the ultra-rich who could spend that much on something dedicated only for either parades or warfare, and custom forged for themselves exclusively. It took months to construct these suits so that they would allow enough mobility to be useful, and that utility varied widely. Again, this was quite expensive. You didn't want to fall into a pond or a deep patch of mud wearing this stuff, either. See <https://en.wikipedia.org/wiki/Frederick_I,_Holy_Roman_Emperor>, and the many French knights who fell from their horses at Agincourt and drowned face-down in the mud. Some suits of heavy armor were specifically designed to be worn only on horseback and were so heavy that the knights needed cranes to hoist them up onto their horses. These, along with the horses, were the battle tanks of the time. In reality, most metallic armor was constructed of bands or scales sewn onto padded cloth or leather, or chain mail suits with a few strategically placed plates that offered little protection against blunt force. The punch of a .45 round provides plenty of blunt force even without penetrating this kind of armor (which it likely would). Even mail armor was rather expensive. Aside from that, the rest of anything that can be considered armor would have been cured or soft leather and padded cloth. It is possible to forge hardened plates that would stop, or better yet, deflect this projectile, but the resulting armor would be terribly heavy. What is the metallurgical level of your world? Do they have the skill to harden steel, and how good is the steel they make. Material tech is important here, but plain old mild steel would need to be thick, and therefore heavy. If the steel and hardening techniques are available, one might be able to wear this on their chest and maybe as a helmet, but a full suit of it would be very difficult and clumsy to move around in on a battlefield and would afford a marksman plenty of time to aim for a soft spot, and it would be exhausting to wear for any practical amount of time. Many medieval battles lasted for hours, if not days. The armored knight would be a sitting duck, essentially. I don't want to write your story for you, but maybe your denizens would figure out that pistols need time to be reloaded, and maybe they could figure out that layers of wood and sheets of steel would make fantastic tower shields to stop initial volleys of bullets that once survived make the shooters the sitting ducks to be butchered a bit later. The Greek phalanx made effective use of this sort of wall o' shields; that's an old trick. Tactics win, armor and weapons are not the only keys to victory. The point is that softer materials and layering might be discovered to be more effective at absorbing the kinetic force of a bullet than single plates of metal. Shields can be dropped, and the warrior behind it then has good mobility to advance and slay a reloading pistolier (but they'd better hurry!). The English longbow and bodkin points on the arrows essentially invalidated medieval armor and ended the "arms race" between weapons and those types of armors. Once full suits of armor became obsolete, the focus shifted to mobility. There were plenty of breast plates worn right into the 19th century (some armor is still better than none), and generally by cavalry forces, but due to cost considerations, the growing size of armies, and the change in strategy to speed over brute force, combined with the improving quality and effectiveness of firearms, armor virtually vanished until material science caught up in the 20th century and it was possible to construct plastic armors that would stop bullets. When you get hit by a bullet wearing this stuff, it still knocks you on your butt, can break ribs, and so forth. Bullets pack a whallop. [Answer] It looks like it would depend on the particular plate armor. The tricky stat to find is how thick of steel you need to stop a bullet. The kind of people who are interested in stopping bullets are the kind of people who are willing to make it just a bit thicker. You know, just in case. I found lots of people who would vouch for stopping a 9mm or .45 with 1/4" steel plates, especially if you have it at an angle. However, for a lower bound, I did find one [anecdotal argument:](http://www.warriortalk.com/showthread.php?2187-Steel-Plate-to-stop-handgun-bullets) > > I am a restaurant repair tech, and I happened to be on site for a shooting. .45 ACP FMJ did not penetrate 16 gauge stainless at 8'. It did however make quite a mess of the syrup lines that were hit. > > > 16 gauge is 1.518mm thick. The thickness of plate armor varied by quality, by there's [evidence for plate](https://historum.com/threads/average-thickness-of-plate-armor.184151/) between 0.75mm and 2.5mm thick, with 1.5mm being common. So I'd say its reasonable that the armor could protect you from a .45 as-is. Of course, there is the question of steel quality. If the anecdotal evidence is to be believed, there's a question as to whether medieval steel could stand its own against restaurant supply stainless steel. [Answer] Steel armor has been played out here. Ceramic armor could almost certainly have been crafted by 14th century artisans, and would almost certainly be able to stop a bullet. Whether they would think to create it themselves is a matter for your story. [Answer] COMPOSITE ARMOR Back the steel plate up with molded ceramics and then silk glued to this. You would also likely need some thicker wool padding to help absorb the blunt force. The armor likely wouldn't be able to take many hits, especially to the same location, but this would easily defeat 45ACP without adding "much" more weight. Details: Original plate armor steel would likely not be the best that 14th century metallurgy could come up with to as part of the laminate armor system, but should suffice. As with anything, over time, accidents and research would lead to a more deformable steel. Ceramics are well detailed as being an integral part in many laminar armor systems. Even cheap home improvement bathroom tile can be used, so 14th century ceramics should be a usable alternative with maybe some minor chemical changes. Silk was used in body armor for quite some time. It is more there to catch any small pieces that may make it through but more to keep the ceramics layer from completely shattering in to powder. And the padding can be anything and was actually part of many plate armors for the same use as for this, so probably wouldn't be anything new. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 5 years ago. [Improve this question](/posts/120571/edit) At university my peer group started to use the saying "it could be worse, there could be zombies" as a way to tell people to keep things in perspective. The statement always implied two things: 1. There is no situation that cannot be made worse by adding zombies. 2. If there are zombies the situation is as bad as it can get. Except by adding more zombies of course. In this question I would like to examine the first implication: what, if any, are the situations that cannot be made worse by adding zombies? Good answers will examine in detail what would happen if zombies were introduced to the situation and how this fails to make things worse. The best answers will show situations where zombies are actually advantageous to humanity's continued survival. The zombies in question are assumed to be slow plague zombies per the novel [World War Z](https://en.wikipedia.org/wiki/World_War_Z); unnaturally mobile dead people with a slow shambling gate and a bite that kills the living, turning them into fresh horrors. Answers should assume something that generally resembles the world we know, which means that humanity, as a species with some form of society, need to be able to survive any scenario you suggest - an atmosphere of pure acid is not relevant, nor a trip to the surface of the sun. [Answer] As Raditz\_35 states above if you have some sway over the zombies then there are many situations, by sway i mean adding them to a rival. However if you mean a zombie apocalypse type situation, then only a couple come to mind: You are under siege it sounds counter intuitive but as the zombies as the least racist or biased an enemy can be, they would attack your enemy as much as they attack you, and if you're in a well stocked and defended position, with decent walls that have no weak points then a ZA, could be fairly easy to limit within your walls, but outside it would be a lot harder to keep under check, and all that would happen is you would change an intelligent army for a dumb one. Explosive decompression in space in space no one can hear the zombie moan. also it can't actually get to you, but one down on earth means no supplies to you up on the space station. so that's bad, but if you were about to be exploded out into vacuum, then zombies wandering around isn't really going to be that bad. Basically anywhere that a zombie is not add an advantage, and you are in a really bad situation then adding zombies is progressively less detrimental Declaring Bankruptcy, or in massive massive debt You had money and now you don't, thats bad, then the ZA comes along and makes money fairly unimportant, same goes for credit card debt, if all the banks collapse and the power goes out then you don't need to pay up. dealing with the zombies is still an issue, but it depends if your a glass half full, or glass half empty sort of person Taxes this only works as long as the ZA is unending, but while the ZA is in full swing, not more tax return paperwork... [Answer] You're a necromancer Your lifelong goal has been to create zombies. Congratulations! You did it! Now, I hope you remembered to make these the kinds of zombies which obey you. Your job performance review is about to begin The zombie apocalypse won't last forever, and in the meantime you can expect to receive significantly less criticism about your client retention or time management skills. Sorry boss, we'll have to discuss those long youtube breaks later. Zombies are at the door. Your classmates won't stop making a crappy joke Oh they'll stop when the zombies arrive. You are part of the resistance in a totalitarian dystopia. The resistance has always been suspicious that their neighbors were dangerous. Now all those suspicions are confirmed and their survival plans are effectively validated. Little did they know that they had been preparing for this exact situation all along. Plus, the government doesn't have the capacity to maintain control over the population when 70% of them are zombies, so the resistance has hereby succeeded in taking down the government. You work for Google/Facebook Everybody is mindlessly addicted to your products already. Now that they are actually zombies, instead of just metaphorically, things don't change all that much for you. In fact, controlling them with technology may prove to be even easier. You're placing last in a race, but the zombies are at the finish line All that fast food has finally paid off. You're the only person who noticed the zombies at the finish line in time to turn around. But now can you make it to safety before the zombies finish "congratulating" the victors? [Answer] Other human predators that are deterred by zombies. Imagine large, fierce human predators. They are not particularly nimble but they are strong - maybe like giant lions or the Alien queen from Aliens. They want to eat people, or lay their eggs in people, or something else that turns out badly for the people. These Fierce Ones are spectacularly hard to kill. But between you and your ragtag bunch of refugees and the Fierce One who wants you is a giant milling mob of zombies. The Fierce one will have to wade through them. Yes, she can knock them down by the dozens, but it takes her 10-15 seconds to permanently incapacitate one, and there are hundreds that will mob her. The Fierce One will not become a zombie, but she is not immune to being bitten and the bites hurt. A nice thick wall of zombies keeps you in but also keeps other stuff out. Other fierce human predators deterred by zombies include other humans - a scenario which is bread and butter for Walking Dead but less fun. [Answer] The earth have no oxygen. It cannot be made worse by adding zombies. It only could made it better as zombies (we assume) are not requiring air but still move. You make the situation better by adding possible solution. You are manufacturer of guns and ammo going through hard times due to regulations. You add zombies and your problems go away. The hunting season is open. And what a glory, YOU ARE REQUIRED to make ammo that explode flesh. The situation is at we see now. You introduce some zombies. The medical breakthrough thanks to ability to research this type of body stasis is unheard of. We know how to preserve food in the best way possible. We can create sources of energy that don't require fuel "Just one zombie per home give you enough electric to cook turkey for 5 hours at 9". Medical wonders of saving life is so easy. You don't need to worry about people dying from various reasons (100 problems) all people can focus on just reversing from zombie state to regular one (1 solution). For fun: reason why taking the zombies AWAY make things worse. The zombie appears, two days later we have cure for zombiesm. The problem is that you literally beheaded everyone in the 5 miles radius. There are more people dead because of you than because of turning into zombie. [Answer] All you need is a scientific experiment with the goal to create zombies. The situation is pretty bad at the start. You are the laughing stock of the scientific community, your only funding comes from some crazy cult perhaps and you still drive that car you had as a student. Now you add zombies. Yes, you could add them in a way that would make it worse, but let's assume you add them into some sort of cage, so that you don't die and so on. Congratulations, simply by adding zombies, you have solved most of your life's problems. Who is laughing now? You can now even send them to eat the people that didn't give you a decent research grant. [Answer] A non-serious answer... --- You are an all powerful wizard who is trying to protect a piece of your soul. You need a deterrent for the pesky people who are trying to collect and destroy all your soul pieces to kill you. You have no qualms about killing anyone, so you set loose a disease that will infect everyone who gets bitten. You collect batches of these zombies and store them in your hiding places to pounce on unwanted visitors, while the rest distract the world from your dastardly plots. You can fly so you have no issue of getting bitten. --- More serious answers... --- Options 1. You live on an isolated island, so there's no danger of people visiting and spreading the disease to you. If anything, now foreigners won't be bothering you because they'll all be dead. 2. You are a Doomsday Prepper and have been waiting your whole life for this to happen. You have the guns, the fortifications, the plans and food prepared and ready. You've been training for a good portion of your life for this - thank goodness you were right and didn't waste your time. 3. You were on death row or being held captive by an enemy and tortured. Now zombies have overrun everything and you can finally escape. Better to face the unknown than certain death. [Answer] Scientists/dermatologists: "guys, we need to do clinical trials but we can't as the FDA won't allow it." Zombies: "meeeeuuuuh" Dermatologists: "perfect to test my new skin cream!" Scientists: "pinch me I'm dreaming, I'll take 3 for this potentially lethal drug test!" Edit: Mythbusters: "We've got a new Buster, the Pool is open how long this one will last!" Anyone testing safety with dummies, ballistics gel or whatnot: "we'll take a few dozen a month, dont wrap em we'll use them immediately." [Answer] Every human is uploaded into a computer simulation by an AI as part of its ultimate goal. If you then plop into existence a group of zombies, there would be no one for the zombies to bite and infect. Ergo they would not make the situation worse and there would be still "humans". The zombies are too stupid to upload themselves into the simulation and with no biological humans around they would just wander around until they decompose. [Answer] And now, for the hit new post-apocalyptic game show: "Run Over That Zombie!" We have all those straggler zombies from around the nation that YOU, our lovely all-American audience, has reported to the Zombie Force to prevent them from murder! What better way to remember those who sacrificed themselves in the most gruesome war that united humanity and every nation of the world than to run over our monstrous enemies with a big monster truck?! ...nottomentionthedeathrowinmatesweturnedintozombiesaswell... And here is our host: Ted Nugent! [Answer] ## Any situation where zombies would interfere with the worse situation, would imply that adding zombies would improve the situation. There are many examples but here are a few: An evil cult of people is killing every person in the world one by one, and has finally eradicated their last opposition. Add zombies. The cult now has opposition again. Alien planet Y's biome of flesh eating bacteria is about to collapse because there is not enough food. So it is converging on humanity for a nice meal. Add zombies, situation improved. They can eat the zombies instead of us. Live in a dystopian rigorous society where your every action is controlled and life is unbearable. Add Zombies. Either the society collapses and you're free, or you die and you're free. [Answer] # Judean Zombies' Front vs Zombies' Front of Judea You already have one group of zombies running around, the apocalypse has begun and all hell is breaking loose. Suddenly, a whole other group of zombies comes along. They hate each other so much that they just fight amongst themselves (because what have the Romans ever done for us, right?), and the apocalypse more or less subsides as long as these two groups are locked in eternal struggle with one another. # You've said to your wife that this fish is good enough for Jehova You're about to be killed in a gruesome manner: stoned to death by a crowd of women wearing fake beards. You keep saying Jehova, because how could it make things worse? The zombie apocalypse is not a bad thing. It can kill the crowd, or at least make them not kill you, thus improving your chances of seeing another sunrise. Or, if you died just before the apocalypse, might as well come back as undead rotting flesh. That's also something to look forward too! [Answer] ## Zombie Powered Power Plant Your post apocalyptic power plant is a bunch of human sized hamster-wheels run by zombies. You currently don't have any of them "powered" Add zombies and suddenly you've got power. [Answer] ## Anti-aging technology has left humanity on the verge of starvation by overpopulation. Sure, a zombie apocalypse isn't pleasant, but zombies use surprisingly few resources, provided you can keep them out of the cow herds. A good sized zombie apocalypse is just what is needed to keep the human population from eating itself to death. [Answer] Zombies show up in a biathalon competition. So what? They can't even remotely keep up, everyone involved is armed and an excellent shot, a zombie that's in the way will be easy to take down with a head shot. [Answer] Vampires have found a way to resist sunlight Vampires are stronger, faster, smarter, and just as tough as zombies. They can choose to make more vampires or just kill outright. Give them SPF 5000, and they become a ZA on steroids. If anything, adding zombies to the situation would make things better, because the vamps would fight them, not wanting the competition. Super Zombies Sure, normal zombies are bad. But if you already have fast zombies, or burning zombies, or flying zombies, are normal zombies any worse? [Answer] Try [grey goo](https://en.wikipedia.org/wiki/Grey_goo). It eats pretty much everything (except for some Unobtanium you'll use for surviving) and it can't be killed by shooting/crushing it's head for it hasn't got any (plus it'll just eat your bullets/hammer). If it's a colony of robots, you can add some hacker character who'll find a way to turn them down before it's too late. [Answer] 1. I'm already a zombie - now I've got friends! 2. I'm about to die anyway from sharknado/cancer/plague/asteroid strike/... 3. I can't stand living next to a chicken farm but love the smell of rotting flesh? [Answer] A situation that can't be made worse by zombies? An asteroid is on a collision course with Earth and the size and speed indicate that it will cause an impact several times as bad as Chicxulub, exterminating all land life on Earth and maybe all sea life too, and the asteroid is far too massive to divert in time. or: An asteroid is on a collision course with Earth and the size and speed indicate that it will cause an impact several times as bad as Chicxulub, exterminating all land life on Earth and maybe all sea life too. Fortunately space defenses are now advanced enough to divert the asteroid safely with five years warning. Unfortunately the asteroid will hit in 3.92 years. A star is on a collision course with the Sun and will cause all the planets to leave their orbits before it hits the Sun and makes a giant explosion that will vaporize all the planets. Of course in those hypothetical situations the zombies might kill you sooner, before the great catastrophe kills you. How about this: Alien spaceships materialize above Earth and emit deadly radiation so all lifeforms on Earth die within three hours. ]
[Question] [ Here's the idea: Building a "jet fighter" that can operate in extended combat conditions with no atmosphere without losing air superiority in atmosphere. It's not going to have both traditional jet engines and rocket engines. The jet engines would be deadweight in purely space combat, and the rocket engines (oxygen tanks included) add extra weight in atmosphere. Worse, an engine that needs to expel matter to produce momentum risks running out of fuel in an extended fight. In this setting, practical "impulse engines" that push against the fabric of space-time haven't been invented yet and probably won't reach the market for another 100-200 years. This calls for an electromagnetic engine that emits a massive volume of photons with combined momentum per second comparable to a late 2010s-era jet fighter engine. Assume a suitable power source is already available and the combined thermal profile (generator + engine) is comparable to a modern jet fighter. The main challenge: figure out an appropriate wavelength for the engine output that doesn't burn, cook, blind, or irradiate the ground crew. The hazard zone behind the engine should be comparable to a traditional jet engine - or smaller. Additionally, it must not produce EMP-type effects that damage or interfere with electronics further than 100 meters away in a cone shape behind the engine. The volume of photons would be massive considering that each photon has only a tiny amount of momentum. Obviously, any sort of ionizing radiation is out of the question due to environmental damage and health concerns. Visible-spectrum light is a poor choice because it would instantly blind anyone who happens to look at the engine the wrong way. Infrared can't be used due to the known health hazards of intense infrared radiation (<https://en.wikipedia.org/wiki/Infrared#Health_hazards>): "Strong infrared radiation in certain industry high-heat settings may be hazardous to the eyes, resulting in damage or blindness to the user. Since the radiation is invisible, special IR-proof goggles must be worn in such places." A microwave engine is a bad idea because the engine output might knock out electronics from miles away in a manner comparable to EMP weapons. NOTE: the engine in question is open-ended, not a closed reflective "EM-drive" chamber. This leaves only extremely low frequency/long wavelength radio waves as the remaining option. The question: Is it possible to pick a wavelength long enough to avoid causing thermal or optical damage to the ground crew and nearby population while also preventing EMP-type damage to electronics? [Answer] # No What you're describing is a [photon rocket](https://en.wikipedia.org/wiki/Photon_rocket). For a perfectly collimated beam, thrust vs. energy output is 300MW/N. An [F-16](https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon) has a maximum, full-afterburner thrust of 128.9kN. To achieve that same thrust, you would need to output a total photon energy of 38.7TW. For comparison, total electrical generative capacity on the planet is 10TW. There is no radiation type that would produce thrust and not do horribly destructive things to the atmosphere behind it, and by extension everything looking at it, near it, under it, or probably for many kilometres in every direction. You would also need a magic energy generator, but the text of the question indicates that that is not a problem. Generally speaking, it's wise to remember the [Kzinti Lesson](https://larryniven.net/kzin/worlds.shtml): > > a reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive. > > > Your proposed spacefighter's primary drive is the mother of all laser cannons. Once in atmosphere, it would carve a blinding, blazing line of dissociated atmospheric gases across the sky. (All assuming that the thrust is never directed downwards.) [Answer] Why not a hybrid engine. Problem: Whatever you do, whichever method you pick, you need to expel matter at specific speed or equivalent amount of energy to obtain trust. Since matter energy equation (e = mc², c² is a huge number) favors matter so much, expelling pure energy for propulsion is not a good idea. You will be expelling too much energy for it to be safe. This hybrid engine intakes a gaseous matter and heats it up to plasma, and pushes itself using this. In atmosphere, it will use intake to get the matter, heat it up as much as it can and it will provide trust. In space, or less dense atmosphere, the highly compressed gas stored in the tanks will be used, it will be heated more to obtain better push with less material expended. You will need to fill up often if you want a lighter fighter. Or if you store large amounts of matter, you will be able to last longer. Best of them all, if you can handle life support, out of combat, these fighters could cover as much distance as you want in space. For instance, you can dispatch them from Jupiter to fight at Mars. When they reach to their destination, their gas tanks will still be almost full. When they are lower, they can hit the atmo to fill up the tanks. As long as there is fuel to burn they will be in the fight. We are very close to (or we already have) this technology. Only problem is a very strong power source. A nuclear/antimatter powered fighter would be an excellent idea. [Answer] ## Abuse the power source The answer by jdunlop indicates the main problem. However, let's assume that this power source can produce arbitrarily energetic photons in exact ways. We can now borrow from supernovae, specifically pair-instability supernovae. These occur when photons are produced with enough energy that a collision can convert energy into mass. We'll be scaling up slightly, and converting our output into neutron-antineutron pairs. These will be moving "rather fast" and have no electric charge. This means that, if we direct them appropriately, we can fire them into empty space. But wait ... if we can create particles with our photon drive, why are we using uncharged particles? Instead, let's make some electrons and positrons, and give them an electromagnetic kick via the photoelectric effect. We suddenly have a decent reaction mass to work with, and handwavium can scale this up to whatever size we need. Firing near-negligible masses very fast is far more effective than shining a beam alone. [Answer] The problem of running out of fuel is going to exist whether you're expelling the "fuel" directly or converting it to radiation and expelling that. Obviously if you can convert matter directly into energy then very little fuel is required; but if you have access to that kind of energy there are a variety of ways to use it for propulsion. As @jdunlop points out in their answer, radiation of any form is going to be dangerous in that quantity. Indeed, anything with high enough momentum/energy coming out of the back of your jet is going to be dangerous, which presents an unfortunate trade-off between efficiency of the engine and danger to bystanders. [Answer] I think you might be looking for a [vasimr engine](https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket). > > It uses radio waves to ionize and heat an inert propellant, forming a > plasma, then a magnetic field to confine and accelerate the expanding > plasma, generating thrust. > > > It is an engine, uses long wavelength EM(radio). Test engines have been constructed and tested. Problem: they operate in vacuum. VASIMR engines are inefficient, and to get energy density nuclear power plant would be needed. if those are being used then there are other more efficient options. A fusion power plant could allow a rocket to be run both atmosphere and space with some reaction mass. But that is not the engine type you are asking about. I thought I read many years ago about combining VASIMR with RAM/SCRAM but that would still leave the problem of how to get from ground to mach. A single atmosphere and space engine that works using EM to add energy to a reaction mass? Currently no, near future no. Far future, probably not. Personally I believe fusion engines would fill the role, if the role is even reasonable in the future. ]
[Question] [ In many Sci-fi books, films and video games, the baddies need to have something that sets them apart from our strong jawed heroes. Typically in the form of a gas mask and trench coat (especially if they are space Nazis, hiss), and while looking both cool and good little black targets, it did get me thinking: Why would a future military field a trench coat? Asides from looking evil, possibly giving some warmth, comfort and maybe some protection if made of the right stuff, I just don’t see any practical reason why the standards issue uniform would be the trench coat. But I would like to know if someone else have any other ideas. Some points the base our assumptions of of: * the environment that these uniforms are deployed in are earth like and in door. For sake of simplicity, environments like vacuum and extreme worlds such as Titan (Titans a moon I know) are going to be ignored. Because they would require a space suit to survive. Though if you want to add a reason why a Astro solider would wear a trench coat in such conditions, be my guest. * the military has access to advanced materials like CNT, graphene, spider silk, future polymers etc. * the length of the coat will be split into two types; long, which reach above the heels; and short, which hang around just over top or bottom of the knee’s. Any shorter and it’s a tunic. Please note, I’m asking this question as something to keep in mind of when designing a world(s) I’m currently working on. I do not know if I’ll include trench coats into any setting, it really depends on this post and what I want in this world. [Answer] First, some history. The first recognizable trench coat was first introduced during the First World War, hence the name. It was not, however, invented specifically for the trenches, as the name might imply: it was actually meant to be a lighter-weight, more comfortable and less-fussy version of the 19th century greatcoat. Both had the same overall purpose, however, which was to keep soldiers (more typically, officers) warm while on campaign in cold, rainy western Europe. Some trench coats had a rubber lining to make them waterproof, while others were made of thick, water-resistant and potentially anti-bacterial wool. Trench coats fell out of military use in the early days of World War II, because they could hinder forward movement in the far more mobility-oriented conflict. However, the German military continued to use them, particularly the officers of the SS. I'm not sure what advantage the SS thought this might grant them, and my suspicion is that it was meant to set them apart from the regular Wehrmacht more than anything else. So, what are trench coats good for: they keep you warm, especially when lined and properly buttoned, and if they have the right coating, they can keep you dry as well. Any conflict that were to break out in cold, rainy country, and which does not necessitate rapid attack or deployment, might reinvigorate the trench coat. Silly as it may sound, in a border conflict between the United States and Canada might see the resurgent use of trench coats in the "Cascades" and "Great Lakes" theaters of the conflict. Let's get weirder. Maybe a war has broken out on a planet or moon which rains something really weird: liquid methane, perhaps. Let's handwave up some material that can protect against the extreme cold temperature of such a planet and the negative effects of, well, methane rain, yet is not as bulky as a full spacesuit, YET would not be as effective if it was just worn as an Old Man's War-style tactical leotard. If such a conflict DOES necessitate rapid attack and deployment, but protection from the elements is still a serious concern, then soldiers in protective facemasks and ankle-length trench coats is not so crazy. Ditto for an environment where radiation might be a concern: whip up some magical rad-blocking material, then throw on an extra layer of the stuff just in case, and hey maybe it should cover not just the torso but as much of the legs as possible too, while we're at it. Think an inner-system planet close to an angry sun, or combat aboard a ship with an active reactor leak. Basically, any setting in which flexible coverage providing protection from ambient elements you can come up with, would at least be a setting where trench coats don't seem completely daft. And, I mean, pair it with a good suit and the right hat, EVERYONE looks good in a trench coat, even the good guys. Take that, Space Ratzis. [Answer] # Swiss-Army Jacket (think towel from Hitchhikers Guide to the Galaxy) When you are on the move (as you often are in military conflict) you want to carry as little as possible, so items need to be as multi-functional as possible. If you are at home its nice to have a knife, spoon, and fork, but if you are hiking its nice to only have to carry a spork - even if it doesn't work as well. Likewise, a rainjacket, windbreaker, coat, blanket, and satchel are ideal but having one item of clothing that serves all those functions is much lighter to carry. I read somewhere that the original trench coats had a lot of folds that could be unbuttoned to make a blanket. They can be made to have many pockets to hold many items which makes those items easier to find at a moments notice and also dissipates the pressure off your shoulders. They can be cinched and buttoned tightly to keep you warm, or loosely to let a breeze through. Perhaps, with the fancy material they could be made of, they have even more uses: they can float in case you fall in water, they could serve to keep you warm when needed and cool when needed, they mimic the background for camouflage and break up your outline, they are impregnated with "insect"-repellent (or what ever they want repelled on this other planet), they protect you from harmful radiation, they are bullet proof. Fancy new-age material could also make them super lightweight, breathable, and comfortable to walk/hike in - like hiking in a long, nonrestrictive silk dress that doesn't get caught on shrubbery or paste itself to your thighs. ## Why not just have a skin-tight cat suit that does these things? Sometimes extra fabric comes in handy: make them into a tent during a sand storm, put them on the spikey ground so you can sit, they can partially unzip to create ropes, they can store solar energy from the sun for later use (bigger surface area = more energy), use them as a blanket, if you are stranded lay them inside out so their bright colored lining and large size help people locate you, their inside is printed with instructions or translations or a map in case you are stranded and need to fix your spaceship or talk to the locals but your futuristic army cellphone is out of battery, you can open them up to make a shield (radiation, bullets etc) in case you find some poor soul unfortunate enough not to have a trench coat. The point is if you need something like a blanket or large coat for any reason you might as well make it your go to item of clothing rather than carry it in a backpack while using other things. I'll leave you with a quote from Hichhikers to get your imagination going > > “A towel, [The Hitchhiker's Guide to the Galaxy] says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapors; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the slow heavy River Moth; wet it for use in hand-to-hand-combat; wrap it round your head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter Beast of Traal (such a mind-boggingly stupid animal, it assumes that if you can't see it, it can't see you); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough.” > > > [Answer] When considering future war you have to realize it is simply not realistic. For all the Expanse's realism it still uses humans in its combat ships because it allows us to tell an interesting story. Droney the Drone is simply not interesting unless we give him human characteristics for no reason. It would be easier and cheaper on earth to start building drone swarms that detonate on infantry, guide in artillery shells and dismantle supply lines than it is to maintain tanks, aircraft and infantry. So any future story will immediately be asking for your suspension of disbelief (or hoping you dont know what tech might be available). What do trenchcoats offer over other types of armor? Well they are less form-fitting and more draped over the person. If the trenchcoat is made from a bullet resistant material like spidersilks and graphene/CNT's and other super materials it would offer a layer of highly resistant material that can catch a bullet and stop it over a distance. You still need to spread the force of any shot, so the soldier wears a framework on his body over which the trenchcoat is draped. This framework doesnt have to be any thicker than current bodyarmor. The trenchcoat is stiff as well, making it easier to catch a bullet and reduce the impact. Since trenchcoats cover so much of the body it also offers a lot of protection against shrapnel from grenades, mortars and artillery. Since it is so large it could also be worn over your space-suit, protecting that what is keeping you alive. A layer of Graphene is also hydrophobic, making rain and mud slide off easily. So a soldier could be crawling through the mud one moment and not have to worry about leaving a trail of mud and water behind him the next. It could also protect against some liquid chemical attacks. If equipped with air-screens it might even offer limited protection against aerosol chemical weapons. Perhaps even having a small canister of neutrilizing agent that fills the interior of the trenchcoat when a chemical gas is detected to help the soldier keep fighting or at least survive. Since it is so sizeable it can also have a lot of pockets inside and outside to protect and carry a lot of ammo or gadgets with you. This allows you to use it like a more plausible Batmans Utility Belt. A large trenchcoat can also be used as camouflage, as it is harder to identify the human shape when someone uses a trenchcoat especially one with camouflage patterns. On the other side of the coin it also makes it easier to build decoys as all you have to do is build a scarecrow with a trenchcoat, helmet and gasmask or something similar. [Answer] # Looking good! First have a long period of peace. In this period, the main principle for uniform designer was that it should look cool. For many years, different armies competed mainly in how snazzy they looked on the parade ground. Trench coats look cool. The coolest. Then war broke out. Sure, the coat can be hard to move in, but nobody wants to discard the very symbol of a competent soldier. [Answer] In the future conflict, for the topmost layer clothing you want something which... * offers stealth against sensor suites of all manner of drones by hiding the gear soldier is carrying under a layer of sensor blocking/absorbing material (same principle as having internal weapon bays etc in current stealth aircraft), and by being cool on the outer surface so more difficult to pick up with IR sensors, and have color-changing chameleon surface to deceive image recognition (and human eye). * offers radiation protection * has moderate level ballistic protection, because almost all incoming fire will be indirect or long range, and rely on shrapnel instead of direct hits, or be small caliber from smaller drones etc * includes a built in temperature control system because many battlefields will be unbearably hot * offers good protection against wind and rain for the whole body * is relatively cheap to manufacture, so no full exoskeleton or full-body armor suit (those are for special forces and only worn while on an actual mission) * is easy to take off and put back on when inside bunkers, vehicles etc, because all the above features are going to make it a bit on the heavy side, but you still want to be able to wear it also outside combat * can easily adapt to different amounts of gear being worn under it * is relatively idiot-proof, just another piece of clothing really When you add all the above together, you end up with a future version of trench coat: chameleon color changing surface on the outside, 1-2 cm thick with ballistic protection and active sensor signal absorbing and thermal control layers, future Velcro-like closing mechanism in the front. --- For actual space operations, you want a space suit which can be worn at all times, even inside, so it really needs to be almost a skin-suit. And then when you actually go out into the space environment, you need something to quickly put over the skin suit, for extra radiation and abrasion protection... So basically everything above, still applies, the trench coat just needs to be designed to operate in vacuum instead of in atmosphere (especially for all the temperature control stuff etc). [Answer] The situation demanded for protective gear. And the Powers That Be, in their infinite quest to save credits, confiscated a cargo ship with clothes. The most common item was the Trenchcoat and it snowballed from there. Think that history is funny sometimes. Wristwatches were used among ladies for centuries but they really evolved on the battlefield among officers. The item was handy/desirable and propagated among the ranks. Give Trenchcoats to people in power and the rest of society will try to conform. *They don't have to be PERFECT. Just get them GOOD ENOUGH.* [Answer] # Trenchcoats as semi-disposable outer garment. The conflict happens on a world much like Earth. More or less habitable in a shirtsleeves environment, but there are two things in the environment: * Some nasty gunk, from mud to bird droppings to tree sap. Getting it onto your skin is icky. Getting it out of your body armor is hard work. (Leaving it on your body armor makes the armor icky.) * Some nasty thorns or the like in the environment that degrade clothing and gear. Say waist-high grass with sharp edges. Or thorny bushes. So you want some sort of overgarment that can be cleaned more easily than body armor and web gear, that will resist minor cuts and abrasions, and that can be thrown away if cleaning and mending looks too much work. A standard issue rain poncho hinders movement too much and does not last enough. Enter the trenchcoat. [Answer] Time tested way of getting naked in a hurry. [![flasher dude](https://i.stack.imgur.com/GjTzL.jpg)](https://i.stack.imgur.com/GjTzL.jpg) [source](https://www.deviantart.com/headsmellspuppys/art/Pedo-stalker-flasher-147590119) Your future soldiers live in circumstances where they must get totally naked at a moments notice. Perhaps they fight inter dimensional battles like the folks in the Terminator series, and cannot bring anything with them. They have to be ready to go at a moments notice. They don't want their clothes to be molecularly disrupted by the transporter because what will they wear when they come back. Nothing covers better and is quicker to shuck than a trench coat. Flashers have known this for decades and your soldiers know it too. Film this scene first because it will be perfect for your trailer. When they return from their planar battles, they likewise shed the astral goo and psionic residues and materialize back in their own skins, and pick up their trench coats. The military sews name tags onto them because there might be a few of them in the heap. [Answer] ## They hide weapons. If the military wants to make things look peaceful, you don't want your soldiers waltzing around with their guns out; so hide them in the coats. Is that soldier over there carrying a pistol, or is there an automatic weapon hidden there instead? The environmental protections as suggested by other answers are potential bonuses. [Answer] # They Look Bad\ss Your bad guys need some kind of intimidation factor to keep normal people from bothering them. Trench coats (and gas masks, per your question) obscure the body anatomy in a way that other clothes don't, stimulating people's fear of the unknown (the same reasons clowns are creepy - we dont know that they're expressing). # You can hide Cool Sh\t (tm) What do your Bad Guys need to operate? Probably weapons and some kind of contraband, be it intel, drugs or whatever. What's the best way to hide odd-shaped items? A cloak! What's the least conspicuous way to have a cloak? A trench coat! You could even have bulkier, drapier trench coats for lower-levels, since they need to handle stuff more, and tighter, sleeker looking ones for the upper brass. # Futuristic janitors SUCK The janitors maintaining your indoor environment are horrible at their job! Dirt gets tracked everywhere, it's always wet, there's constant water leakage. A trench coat offers reasonable protection from splashing water if you have to walk through a shallow puddle. You could also drop the janitors and say that the outside world is basically the Pacific Northwest, in which case they also provide protection. ]
[Question] [ In an all out battle between two forces with one side having such advanced technology and weapons that they appear as magic (from now on called wizards) and the other side have nothing but spears and maybe basic bows(from now on called cavemen), could the cavemen still win if they outnumber the wizards? Some more info on the wizards: 1. They can throw fire/plasma 2. They have firearms and bombs 3. They have advanced knowledge of different sciences such as math and physics 4. They are somewhat small in population, maybe with only 3,000 people or so. 5. Their homes are in what appear to be modern (for our standards) houses and buildings. 6. They have an extreme phobia of air travel so they have not invented planes or rockets at this time. Some more info on the cavemen: 1. Their most advanced technology comes in the form of sharpened sticks and simple bows. Some of the smarter cavemen have even started putting sharpened rocks on the ends of the spears and arrows. 2. While they may seem incredibly stupid to the wizards, the cavemen have the potential to become quite smart, they just haven't reached that point in their civilization yet. 3. They are pretty large in population, a low estimation puts them in the 300,000 range. 4. They live in caves and mud hovels Is there a way for the cavemen in this scenario to win an all out war with the wizards? The main war goals of both sides is to completely destroy the other. Peace is not an option. Is the population of the cavemen large enough to eventually take over the wizards? Do I need more? Can I get by with less? --- After trying to genetically engineer themselves to make them stronger/smarter/etc they accidentally unleashed a virus that affected the entire wizard population that makes it incredibly hard to conceive. They blame it on their desires to mess with biology and now most forms of biology are strictly taboo. The wizards used to keep to them selves and were a peaceful people, the cavemen were jealous and afraid of the "magics" that they witnessed and decided it was an affront to their God so the cavemen decide to wipeout the wizards. The wizards, in self defense decide the only way to stay secluded and alone is to wipe out the cavemen. The territory of the wizards is quite small, about the size of a small urban town in Utah: 16 square miles. The wizards are stationary and don't want to leave their home. The cavemen are nomads moving from place to place and that's how they happen upon the wizards. [Answer] Possibly, some examples from history to think about: <https://en.wikipedia.org/wiki/Anglo-Zulu_War> British empire with rockets/rifles/cannons were initially defeated by the Zulus with spears using their superior numbers to exploit the British supply lines. <https://en.wikipedia.org/wiki/Battle_of_the_Little_Bighorn> Custer lost mainly by hugely underestimating the number of the enemy he was fighting. Big picture a larger force can win against superior technology, but usually only due to errors or overconfidence on the part of the superior technological group. Having technology and knowledge does not automatically make them great strategists or tacticians, if anything it's likely to make them overconfident. Second point to think on, technology can be captured and used by the savages. The Native Americans fighting Custer rode horses and wielded rifles. Knowledge and intelligence are not the same thing. Your cavemen would lack knowledge not intelligence, when presented with the technological weapons attacking them they would quickly learn how they function, even if they don't understand how (i.e. when they raise the black rod it shoots burning fire to some distance). If they get into close combat or smaller skirmishes over time they could easily capture equipment and potentially learn to use it. On the wizards side, use of chemical or radiation methods of extermination (gases/poisons) would be quite effective, because the cavemen wouldn't see anything they would just die, which you might want to rule them out for other reasons similar to the biological limitations. [Answer] It depends on what the victory conditions are for each side. If the "wizards" want to exterminate the cavemen Dalek mode, it is one thing. If they want to enslave the cavemen, or to establish themselves as the cavemen's overlords, then they will not want to kill all the cavemen, who will eventually find ways to circumvent the wizards' technological advantage, or to turn such advantage against their oppressors. So, what exactly are they fighting about? Total control, genocide, enslavement, border security, trade rights, the control of sacred or economically important territory? And are we talking about a war or about a battle? (I don't think, for instance, that Native Americans could have repealed British colonisation and kept their territory free from European invaders. But we do know that eventually Native Americans have defeated non-Native Americans in battle fields, as General Custer bears witness to). [Answer] A lot of it would come down to the tactics used on either side. As mentioned above, if the wizards perfected the defense of the land they were guarding (i.e. castles or large walls, and using geographical features to their advantage), it would be tough for the cavemen to stand a chance. These obstacles would pose a serious challenge to the cavemen as they lack all of the required siege technology. There are, however, ways in which the battle could be more even. If the cavemen were able to lure out the wizards by doing something like lighting fires around their camp, or attacking weaker parts of their society (like farms or small villages), the battle would be much more evenly matched. On an open battle field, early stages would look much like the beginning of a world war 1 battle: the cavemen, charging into the defensive weapons of the wizards, would get slaughtered. Much like WW1, however, as soon as the two sides get close enough to engage in hand to hand combat the tide would turn against the wizards. In a typical WW1 battle, with one side armed with machine guns and artillery, the attacking side could lose as many as 100,000 people in a day. As long as the cavemen don't get discouraged, they could potentially make it to the wizards front lines, where guns, bombs, and plasma have less of an impact. Another interesting approach would be guerrilla warfare, a technique used throughout history by technologically outmatched forces. The Mongols frequently used a tactic where they would have a small force engage the enemy and then retreat, prompting their enemy to follow after them. Once the enemy was spread out, other Mongol forces would swoop in and attack them while they were exposed. In the forests the cavemen could use hunting techniques to find, follow, and kill or even capture wizards in small numbers, making the high-tech weapons less effective. They could potentially even taking prisoners, giving them valuable knowledge. If the cavemen were able to get the wizards out of their defenses into a forest or valley, the battle would be as good as over. Overall there would be ways to get through defenses such as laying siege to the city, burning the crops around it, or launching a frontal attack, but most of these would fail. On an open battlefield or rough terrain the cavemen would stand a far better chance. [Answer] I think it depends of the initial defense of the wizards. If they posses the Chinese wall which is secured from the beginning, or know they will be attacked, they will probably win. If not and the caveman will lunch an surprise attack, 3,000 people is to few to survive. If the caveman raided the village at night when everybody sleeps, there would be almost no resistance. Most would be killed in sleep or while waking up. The next big part of people die while in panic. The rest dies fighting or fleeing unarmed before they get any weapons. Only a few would be able to arm themselves and effective fight back. To few. In the last scenario I assume the wizards have an open town design and almost no military facilities. Also normal people don't posses firearms. That what I would assume from an peaceful society. Additional from those 3000 people not all are able to defend themselves. They could be to young or to old. And if they have the correct age, they still cold be in a fitness state where they would be no match for an enemy. The caveman on the other side have 100 people per wizard in addition they will most likely die younger and all young and adult men and woman would be stronger and tougher. So for every wizard that can defend there town would be 120 or more attackers. I could image 20 to 50 people to fend of the initial attack, get some firearms and regroup. Even if they use there superior firepower to kill enough caveman so they will retreat, the wizards would be as good as dead. Most likely all children and older people are dead, without some luck all women also. That would be the end. The survivors would soon run out of essential stuff like weapons, food, fuel, medicine or something else. Higher advanced civilizations have an higher specialization of individual. It is not likely that the survivors will have the knowledge in all fields they need to keep on fighting the caveman. Eventually they will get hunt down by the caveman. --- There is an Anime where an fantasy army invades Japan and more or less gets anhilated by modern weaponry. It's called [Gate](https://en.wikipedia.org/wiki/Gate_(novel_series)) maybe you can get some ideas from there. [Answer] Yes, the cavemen can win. As mentioned by others if the wizards create a secure perimeter, and they have the technological superiority to create one the cavemen are helpless against, they will win by default unless they do something stupid. Sleep safe inside your secure area, go out hunt some primitives with high powered rifles, grenade launchers and set up explosive or poisoned traps, and then go back to safe and comfortable home. Eventually the cavemen would become scarce enough that you'd have to do longer hunting expeditions that set up or return to secure camp each night. Roman legions would have been able to do it, so your wizards should have no issue. Just keep it to hunting, not war, as wars are risky and unpredictable. So why did I say the cavemen can win? Because it is not really necessary to wait and hope your enemy messes up and does something incredibly stupid. (That being the level of stupid required here for reasons explained.) Instead, if you can interact with them, you can directly fool them into doing any level of stupid mistake you need. Incredibly stupid will just take more work and time. Basically, turn traitor to your own kind, make friends with the wizards and help them kill your friends and relatives. And once a degree of trust is established, betray them, kill them all, and steal their magic toys for yourself. If you also wish to set up yourself as a wizard you can keep some of the wizards as slaves to do repairs and training, but doing it safely adds to the effort and timing required to set it up. Since others supplied historical references, I'll give one as well. [Arminius](https://en.wikipedia.org/wiki/Arminius). [Answer] If I ruled the cavemen I would wipe out all the wizards within a year, without introducing any new technology, merely good command and control. The plan is to create a massive [fire](https://en.wikipedia.org/wiki/Wildfire) that encircles and destroys the wizard town. Even today, using planes and thousands of firefighters, forest fires are very difficult to contain. Nothing in the wizard description suggests that they have magic anti-fire abilities. Step 1: I would divide the cavemen into tribes of about 100 people. Each tribe would have a leader, a succession plan, and would operate independently. They would get instructions from me periodically by sending a runner to my personal HQ. Step 2: I would send these 3000 tribes in all different directions, to chop down trees from far away and bring the logs to storage areas. These 3000 storage areas are all near the wizard's town, but hidden away. Some will be found by the wizards. What will the wizards do? First, they might not appreciate the purpose of the logs. If they burn the logs, they risk doing my job for me. They might carry them away using their trucks or whatever, but we have far more manpower and will be bringing the logs faster than they can be hauling them away. Further, if they just haul the logs down the road, one of my tribes might find them and bring them back. Step 3: Once we have plenty of fuel, and the weather has been dry for a while, we light them up! 3000 huge bonfires, lit in a circle around the town, will immediately enflame all surrounding plants. The inferno will spread very quickly toward the center, leaving the wizard town in ashes. If I am able to time the fires to all light at the same time (e.g. at dusk on a particular day), the fire will be a solid circle around the wizards before they are able to find an escape route. [Answer] Depends. Number one: caves and mud hovels (sedentary) are not nomads (mobile). Pick your poison for caveman lifestyle. 300,000 cavemen - cannot all eat from local resources (especially given their low technology level) - without a baggage train, herds of horses/cattle (to kill and consume) - they're going to be unable to bring all their manpower to bear on their enemies. What types of defenses do wizards have, and can their magic generate and/or protect their food/water supply? eg: If wizards grow corn or grain, it will just take a couple nice stampedes or some fire-arrows to put paid to a year's worth of crops. Unless wizards are very well prepared, they're not going to survive two years of this. Cavemen have used fire to hunt / drive herds of animals since time immemorial. If not fire-arrows, then brands/torches. If wizards hunt, cavemen just need to keep their cattle / horses far enough away and scare off/kill all the game in the area (wizards are going to have a tough time feeding 3k people on game from a local area - even with guns). Cavemen will have to hope that they can keep the wizards from collecting enough of their bodies to go cannibal. Nerve poison (poison frogs?) or other nasty biologicals would help. Cavemen need to harass enough to prevent work parties of wizards from putting up walls. It would help if cavemen got better bows (longbows), and better yet if they had trebuchets. But wizards probably don't have enough man-power to man walls for all their fields. Cavemen just need to rush walls, throw up sandbags and dig/bash thru to set fire to crops (or fire arrow over the walls). Cavemen are going to have to learn to dig earthworks to protect themselves from direct fire (guns), and bombs/artillery. Cavemen need to learn about guns quick, and realize they need something between them and wizards. Are magicians' artillery far more accurate than WW1/ww2 artillery? ie: on par with 21st century smart weapons? If not, cavemen just getting their trenches or raids close enough to the fields will result in short rounds taking out the wizards' food supply (or walls) by friendly fire. Cavemen should target the water supply - if it's wells: throw some dead animals in there, or some poison - and they'll put a world of hurt on wizards. Especially if it's a sneak attack. If they've infiltrated the surrounding area, they'll make the wizards have to bring the fight to them, and can be entrenched. If cavemen can restrict water (use that manpower to fill in streams / rivers), they can kill off the wizards' crops. [Answer] Generally, this depends on how many numbers you have and the level of technology difference, but in this case, the wizards will win with your current numbers. Since they have advanced knowledge of different sciences such as math and physics, they'll be able to build armored cars and tanks through which they can stay inside, protected, and throw fireballs out of. They can also build castles/bastions/bunkers/siege huts which the cavemen will never be able to break through, and throw fireballs/plasma over the walls. Since they have bombs, they'll be able to set enough traps down to stop any advance the cavemen want to make while expending little to no effort. They'll also be able to throw those bombs, causing widespread fear and panic amongst the weak race. Of the points I've made above, if the wizards do even ONE of them, the cavemen will already instantly lose. In fact, you could send a squad of 5 wizards set up with an armored "vehicle" which have small grates on the sides for the wizards to spew fire out of into the enemy encampment and essentially wipe them all out. [Answer] No , The wizards could simply create a virus that will wipe cavemen out of the face of earth in few days Even if there were 10^100 cavemen for every single wizard they would still have no chance to survive against a powerful biologic weapon. To give a small chance to cavemen you have to make wizards completely ignorant in bio engineering and medicine. Ok since they can't use biological weapons Then if cavemen have enough knowledge of their environment they can easily take down wizards , the fastest way would be to steal technologies or attack in guerrilla or with kamikaze terrorists. If wizards have a good enough defenses to avoid being destroyed from the inside then the war would be incredibly long and exhausting but eventually wizards will win since their civilians are safe. Between the numbers are not in favor of anyone they are balanced for both sides since only a little portion of the population will become soldiers [Answer] The best example might be the Fall of Rome to the Barbarians. While some may argue that the Barbarians may have had some technology that the Romans may not have had, Rome may have fallen because it was such an advanced society. They had a mode of operation where they were highly regiment oriented. One commander on the ground taking orders from someone in a glass tower who doesn't see what is happening. Bureaucracy which is created by advanced societies remove the decision making power from the front line (in all cases - not just military) which slows down operations. As a result, another less advanced military can do well when they take advantage with lightning quick reflexes. Another couple of examples might be the U.S. Revolutionary War and the Vietnam War. There were many similarities between these two in that they both were fought by one party on home turf and another fighting from overseas who had the superior technology/organization; both cases had interfering third parties that helped the "little guy" (France in America and China in Vietnam); and both resulted in the more advanced combatant losing. In general, you might look at a few wars across history where this situation occurred and try to find similarities between them that you might apply. [Answer] IMHO the "wizards" are a better hope for the future than the "cavemen" and I am more or less on their side. The "cavemen" are described as a nomadic group that discovered the "wizards" on their travels and have a population of at least 300,000. I hate nomads. It is more likely that "the cavemen" are not so much nomads moving around their territory but migrating in search of a new home for some reason and thus they discovered the the "wizards" in lands that they never visited before. "The cavemen" may be either nomadic or sedentary in their home territory but are searching for a new home territory. Unless the land near the territory of "the "wizards" is incredibly fertile, "the cavemen" who are probably hunter-gatherers instead of farmers or herdsmen will probably live in thousands of small bands, each occupying a territory as large as the entire "wizard" territory. So basically the conflict would probably start between the 3,000 "wizards" and 30 or 60 "cavemen" (including women and children) in the nearest band and spread from there. In order to gather a large group of warriors many "caveman" bands would have to stock up on food and send their warriors on long trips to reach the conflict zone. Each band of "the cavemen" is likely to be politically independent of the other bands so it would take unlikely events like all "the cavemen" bands deciding to fight a holy war against "the wizards" to assemble a large "caveman" force of many thousands. I can imagine that "the wizards" wipe out a "caveman" band that moves into their neighborhood. Then after a while another band moves into the area and "the wizards" wipe it out. Then after a while a third band moves into the area and "the wizards" wipe it out. And the leaders of "the wizards" may decide that enough is enough. Instead of waiting for the fourth band of "the cavemen" to show up and wiping it out with ten warriors armed with advanced weapons, they are going to wipe out all the bands of the "cavemen", even if there are 20 or 30 such bands. So they arm and train a force of 200 "wizards" to fight using newer and deadlier and more advanced weapons than they have used before, and keep them ready to move out at a moments notice. The plan is when a fourth "caveman" band is detected to wipe it out instantly and track them back to where they came from and slaughter the other bands in that area, even if there are 20 or 30 such bands. Meanwhile all the "caveman" bands have decided on holy war against "the wizards". Volunteers have formed a decoy band to move into the neighborhood and attract attack by "the wizards", while tens of thousands of "caveman" warriors secretly march in and hide in ambush. When the ten "wizard" warriors seen by the survivors of previous attacks attack the decoy band the tens of thousands of "caveman" warriors will spring out of ambush and over wealm them with numbers. So the stage is set for a battle in which each side will have shocking surprises and find the enemy much more dangerous than they dreamed in their worst nightmares. Who will win the battle, and who will win the rest of the war? [Answer] ## The Wizards can not win #### 1. They have no infrastructure Because these are not really wizards, but scientifically advanced people, we must assume that the wizards came from somewhere else for this scenario to exist. 3000 people in a 16sq/mi area can never achieve more than a Renaissance level infrastructure. Those Plasma Riffles are pretty cool, but making one requires a number of rare elements that do not exist in the same places in the world, and refining processes that require very long and expensive supply chains. If you take the closest technology we have today (High Energy Lasers), you can not build such a weapon with out a multi billion dollar industry supported by millions of people and a long complex series of supply and production chains. So, while the wizards may have 21st century tech, it is unlikely that they will have access to iron ore, sulfur, tungsten, lithium, platinum, uranium, and all the other things that go into modern technologies. More over, they don't even have the man power to maintain advanced industries even if they so happened to have all of these resources locally. So they may know how to make modern magnesium alloy blast furnace steels, but for practical reasons will likely be limited to bloomery carbon steel. They may know how to make modern gun powered, but will probably not even be able find the sulfur needed to make the basic stuff. In short, they have modern tech, but can not produce modern tech of thier own. #### 2. They can't kill as fast as the cavemen can replace thier losses The cavemen are nomads. This means that they are likely moving around in groups of 10-100. So let's say the average tribe is 25 people. If the wizards were to go out and try to hunt down the cavemen, and find 1 tribe every week, they could at MOST kill ~1000 cavemen a year. Out of 300,000 cavemen, this is only about 0.3% of thier population; so, with new hunting grounds now opened up by these losses, they could easily have enough children that year to completely replace thier casualties. So the wizards might win every single battle they fight in. If they are VERY lucky, they might never suffer a single combat loss, but eventually thier plasma guns will need to be repaired or recharged, thier bombs will run out, thier tanks and trucks will run out of fuel, and they will be forced to fight with whatever weapons a group of 3000 people can come up with. Once this happens, they will have to go from plasma guns to crossbow... and this is very bad for your wizards. While a crossbow might technically still be a more "advanced" weapon than a bow and arrow and easier to learn, a trained archer is much better than a trained crossbowman, and every caveman is a trained archer. So, once this happens, even a small handful of Neolithic tribes could come together and wipe out the wizards. ]
[Question] [ In a dream, the image came to me of a modern / future ship driven by ring / cylinder sails. (Well, technically I saw something different, but this is what I knew it was supposed to refer to...) That is, these would be short tubes oriented horizontally that could pivot. Is anything close to this design technically workable? Clarification: The ship in my dream (would have) looked something like this. [![sails lengthwise](https://i.stack.imgur.com/wPMrF.jpg)](https://i.stack.imgur.com/wPMrF.jpg) [![sails crosswise](https://i.stack.imgur.com/CKrFQ.jpg)](https://i.stack.imgur.com/CKrFQ.jpg) Is there anything remotely like this that can work? Note that I'm only asking about SAILING ships. The propulsive force must come from the wind, not an engine. The sails I showed didn't constantly spin, they only pivoted when needed to change course or to deal with changing wind. [Answer] I don't know if its exactly what you're referring to, but [Rotor Sails](https://en.wikipedia.org/wiki/Rotor_ship) fit your description. They are spun rapidly by the ship (via a motor), generating forward thrust via the Magnus effect. I believe you can turn them horizontal if desired, but they are typically vertical to minimize issues with docking or other narrow clearance situations. Some companies have found that they can improve fuel efficiency with them over simply turning the propeller. [![enter image description here](https://i.stack.imgur.com/QDJg4m.jpg)](https://i.stack.imgur.com/QDJg4m.jpg) [Answer] > > Is anything close to this design technically workable? > > > Your boat reminds me of something called a hoop glider. It is similar in that it also uses hoops, but as wings. I think the glider demonstrates how this shape interacts with the air as a wing by creating lift and therefore most likely would never work well on a boat as a sail. [![Hoop Glider](https://i.stack.imgur.com/jKlP8.jpg)](https://i.stack.imgur.com/jKlP8.jpg) [Answer] Given that there is no aerofoil section, I think this would have great trouble sailing into the wind. With the wind directly behind the boat, the cylinders would have to be at right-angles otherwise the wind would whistle straight through them. Even at right-angles they would be less efficient than a flat sheet of canvas such as on an old square-rigger. I think it would sail okay on a broad reach. That is with the wind coming at right angles to the side of the boat. The cylinders would then have to be at 45 degrees to the keel. Ultimately, the best way to find out is to build it. It must have a keel and a rudder. You can buy a cheap model sailing boat and just change the sails. Put it in the bath and blow it with a fan. Make sure not to drop the electric fan into the bath. Maybe adapt one like this. [![enter image description here](https://i.stack.imgur.com/iiJJb.png)](https://i.stack.imgur.com/iiJJb.png) [Answer] ## It works in principle but not in practice. You are just creating a pair of normal sails per cylinder. but is it incredibly inefficient, most of the rings surface generates no propulsive force. You can't tilt the individual surfaces, more importantly there is no way to furl the sails, so you can't stop and your sails and likely ship will be ripped apart during a storm. Even a single lateen sail is going to generate way more thrust, way less dangerous, and way easier to use, plus you can fit more of them in the same deck space, so those will quickly replace yours. It is also can't be built as shown without modern technology, the rings are stable becasue they are tiny, on something ship sized they will either collapse under their own weight or be so heavy they generate more drag than thrust. [Answer] > > " short tubes oriented horizontally that could pivot. Is anything > close to this design technically workable? Is there anything remotely > like this that can work?" > > > ## Maybe these were not purely sails! This could be a hybrid system. How closely did you examine the 'sails' in your dream? They could have been extra-large [Air Multiplier™ Dyson fans.](https://www.jameco.com/Jameco/workshop/howitworks/dysonairmultiplier.html) that also make use of the wind to get a massive boost from entrained air. [![enter image description here](https://i.stack.imgur.com/WISYU.png)](https://i.stack.imgur.com/WISYU.png) [![enter image description here](https://i.stack.imgur.com/bXLvL.png)](https://i.stack.imgur.com/bXLvL.png) [Answer] Yes, it can work. It deflects wind in some direction. The problems that may arise: 1. The shape - the usual sail is kept in its shape by the tension of few ropes. The ropes feed back the force of the wind. Here, you will have to make your "sails" more or less rigid or invent some other way of keeping them cylindrical in the presence of a sidewind. Will work for a model scale, not sure about 10 feet boat. The whole sail will be quite heavier than the flat sails and you don't really want your center of mass higher in a boat. 2. The efficiency. Will be less than the usual sail. 3. The footprint. A sailor can go around the usual sail. Here, in most pivot positions, one will have to go either under the sail (and you want to keep it low, see above), or thru the opening (if it is that much rigid to support a sailor's weight). [Answer] # The sails are mag(net?)ic! (Not magic as involving spells or individuals with power, more like altered physics.) Along the sails sit some kind material with a self repelling Force. I imagine it works somewhat like magnets with their north poles facing the centre of the cylinder, pushing it outwards to maintain its shape. To pull this off with real magnets on our real Earth you would need very strong magnets. One way to solve this is to not use magnets but some magical substitute. The best kind of magical object would repel other similar objects in all directions, as strong magnet-like two-sided forces would be rather dangerous I think. Another way, if you want to keep magic out of it, would be to have this take place on a planet with much lower gravity. Who said your dreams must take place on Earth? Why not a smaller planet with a dense atmosphere and abundant magnets? (The resulting magnetic field around the planet would also help explain how a small planet could maintain its atmosphere!) So. Let's assume you have managed to shape the sails, how to use them for propulsion? There are many nice answers on how they need to be shaped to generate lift, so I'll not dwell to much on that. One thing I haven't seen is a suggestion on how to change their shape. My suggestion is to simply have ropes inside channels along the rims, which you can pull tighter or loosen, like the strings on a hoodie. This way you could have them more or less conical as needed, and so they would work even with the wind in your back, and you can even fine-tune how much force you get. Of course you could also turn them as needed to propel you in the direction you want to go. One advantage, like @Turksarama notes, to normal sails could be that you could also generate some lift and reduce the drag of the water. In a low-gravity setting, a ship might even be able to briefly take off if it's not too heavily loaded and the winds are right! If you opt for magic (which IMHO is the cooler option) I would suggest that the ring of repelling Force also makes the air inside the cylinder slightly thinner than the ambient air. This would speed up the air moving through and thus enhance the lift. Note that the people using the ships don't have to be magicians; they don't even need to consider the Force magical! They just know that in certain places you can find self repelling nuggets. Maybe the cylindrical sails are fancier than normal sails so that rich people use them to show off, maybe they are common. I've never been to your dream world, so I won't pretend to know. I think this is a really cool idea! [Answer] ### Yes but... As other answers have said, you need the sails to form an aerofoil section, and wind passing over the aerofoil generates a force perpendicularly to it. On a plane wing, the aerofoil is horizontal and the force is vertical. On a boat, the aerofoil is vertical and somewhere outside of straight down the middle of the boat, so it generates a horizontal force with some forwards and some sideways. The keel opposes the sideways force, so you only get forwards motion. If you shaped the ring appropriately, you could give it an aerofoil cross-section to the ring sides. That should create appropriate forces in the same way as a sail, as the wind passes over it. Having parallel sides with opposing directions of aerofoil is going to be a problem though. The force generated by one side is going to be opposed by the other side. Flaring the sides out, so the ring cross-section is maybe 45-degree line, will give you some assymetry which would give you different net forces (because each aerofoil will present a different angle to the wind). So it's physically possible. What it isn't going to be is efficient, unfortunately. You can certainly build one though. [Answer] Lift and drag forces both can be used across your sail to provide propulsion. [![enter image description here](https://i.stack.imgur.com/LgxrLm.jpg)](https://i.stack.imgur.com/LgxrLm.jpg) [![enter image description here](https://i.stack.imgur.com/wPMrFm.jpg)](https://i.stack.imgur.com/wPMrFm.jpg) Assuming no vertical angle-of-attack $\alpha$ (won't assume that in bit), the profile of your sail providing force perpendicular to the surface (per mast) is twice the sail diameter high and the full width of the sail wide. $A \approx 2Dw$ The total amount of canvas is $A = \pi Dw \approx 3Dw$. You learn something interesting from just this. In this configuration, you've lost roughly a third (33%) of your canvas available for thrusting. What have you gained? By the same reasoning, roughly two-thirds of the canvas air is now available for lifting. The equation for lift is: $L = {1 \over 2} C\_L \rho\_{air} (v\_{air} - v\_{ship})^2 A$ The density of air ($\rho\_{air}$) is 1.1 ${kg} \over {m^3}$, and the lift coefficient ($C\_L$) of a sail can be up to 1.4 (see chart below). So, the equation above becomes. $L = (0.5) (1.4) (1.1) (v\_{air} - v\_{ship})^2 A = 0.77 v^2 A$ For a ship like a Caravel with about 100 square meters of canvas, A becomes about 66 square meters and the equation simplifies a little further to - $L = (0.5) (1.4) (1.1) (v\_{air} - v\_{ship})^2 66 \approx 50 v^2$ Thrust from lift, neglecting using drag for thrust, is the same $T = (0.5) (1.4) (1.1) (v\_{air} - v\_{ship})^2 66 \approx 50 v^2$ Drag, the force countering thrust to slow the boat, comes from skin friction and displacement. In a Caravel shaped boat, mostly displacement. $D = {1 \over 2} \rho\_{sea} v\_{ship}^2 A\_{profile}$ Where the density of sea water is 1,200 ${kg} \over {m^3}$ and the boat profile is the width (2 meters for a Caravel) times displacement (also 2 meters for the Caravel), and the equation above becomes- $D = {1 \over 2} 1,200 v\_{ship}^2 4 = 600 v\_{ship}^2 4 = 2,400 v\_{ship}^2$ [![enter image description here](https://i.stack.imgur.com/7WgJGm.png)](https://i.stack.imgur.com/7WgJGm.png) Let's try this out at a few speeds In leisurely 15 knot ($\approx 7.5 {{m}\over{s}}$) winds, $L \approx 50 v^2 \times 2 masts$, you get about 5,600 Newtons of lift per mast. That'd offset the weight force of about 560 kilograms. And, for a 50 ton ship, isn't really significant. Might be good to work out cruising speed and compare it to a ship with flat sails. At cruising speed, the thrust being generated by the wind is being totally balanced by drag force (so that the ship is neither accelerating nor slowing) $T = D$ For our ship $T = 50 (v\_{air} - v\_{ship})^2 \times 2 masts; D = 2,400 v\_{ship}^2$ I don't have any way other than trial-and-error to solve for that, so maybe take it with a grain of salt that your cruising at 1.2 $m over s$, or about 2 knots. A Caravel, our reference ship, would be travelling in the same winds at $T = 77 (v\_{air} - v\_{ship})^2 \times 2 masts; D = 2,400 v\_{ship}^2$ at about 3 knots (or 50% faster) Things start to get interesting in high wind With a strong 45 knot wind (22.5 m/s), things start to become interesting. $L = 50 v^2$ \times 2 masts$ = 50,000 Newtons. Or, 5 metric tons of weight. For a 50 ton ship, it's about 10%. The drag of the boat hull is based on it's width (2 meters) multiplied by how deep it's sitting in the water (also 2 meters). The tonnage of the boat is the displaced 1,200 kg/m^3 sea water = 2 x 2 x 10 x 1,200 ~ 48,000 kg. Lift, pulling some of the weight off the boat, means the boat will sit higher in the water. About 10% (0.2 meter) higher in this case. This has 2 benefits : * Can sail in shallower water * Can move faster In this particular case, being 10% higher in the water increases speed by about 5%. We're closing on the performance gap with the comparison ship : 8 knots (us) vs 9 knots (comparison). What about dangerous conditions? At 60 knot winds (30 m/s), the boat is 10% (0.5 meters) higher and still a little slower than the comparison ship (11 knots vs 12) How about a lighter ship? As you can see, lift vs. weight is how this effect scales. Decreasing both our reference ship and ship's tonnage by half to 25 tons, the cylindrical sail finally starts to outperform it's competitor. The ship sits much higher in the water at 60 knots winds (0.6 meters total displacement) meaning invisible coastal shoals are much less of a threat. It also sails faster: almost 19 knots in these conditions, vs the competitor at 16 knots. Going further Modern competition boats, I read, are about 6 to 12 tons. In this case, it seems, you're nearly on top of the water and much faster than the competition at 30 knots vs 26. Lift is getting cut as the relative wind ($v\_{air} - v\_{ship}$) decreases with increasing boat speed. Would need to re-formulate how lift works to really explore this area. I think there are other questions about stability and how to control the thing, but it seems like a very interesting concept! [Answer] If you're willing to allow a little flexibility, sort of. Make the sails as parachute foils, arranged as in a standard rectangular ram-air parachute, but with the edges extending down to the deck (to make most of a circle) and enormous. Add a line from the front of the sail down to the deck somewhere in front of the sail. Then you can: 1. Generate thrust downwind by leaning the sail forward (essentially making a square sail high up), or convert that to movement in any direction below a beam reach by using the ship's keel to cancel out most of the lateral force. 2. Steer by pulling down on either side of the parachute, exactly as skydivers steer. And that gives you pretty much everything you need for a functional ship. Indeed, you can buy [something vaguely similar](https://skysails-marine.com/index.html) today. [Answer] # EWICON: Electrostatic Wind Energy Conversion Your "sails" could function as [ion wind generators](https://en.wikipedia.org/wiki/Vaneless_ion_wind_generator), based on a principle first demonstrated by [Lord Kelvin's Thunderstorm](https://en.wikipedia.org/wiki/Kelvin_water_dropper). The idea is to use masts shaped somewhat like tennis rackets along which you expose (sea) water to the open air. Wind action physically removes water droplets from the masts, inducing a static charge in the masts that can be utilized as electric energy, for example to power the vessel's propeller through an electric engine. A major advantage of this scheme is that efficiency is more or less the same from any wind angle. EWICON in its current form is a recent innovation originating at the University of Delft in the Netherlands, where the technology is being [actively developed as a means of power generation](https://www.mecanoo.nl/Projects/project/61/Ewicon). [Answer] If you really tried, you could make a boat sail like that, but you wouldn't want to. Compared to conventional triangular sails, it presents many problems and no benefits. * Most of the "sail" doesn't do much work, since it isn't vertical. * Difficult to maintain a good airfoil shape. The rigging would be quite complicated. * A lot of unnecessary weight aloft, that the keel has to counteract in order to keep the boat upright. That makes the boat displace more water and move more slowly. * Looks like it's difficult to adjust the sail area for varying wind conditions. It's kinda like how you could make a car with wheels that aren't round... but why bother? [Answer] Essentially you'd need some form of way to apply force to the middle part of the annulus/loop. Two highly exotic ways to do that would be: ## Some acoustic propeller thing: You could use the interaction of acoustic waves with the wind to "suck" momentum out of the wind and into the sail frame. You'd need some kind of very powerful acoustic emitter to send the waves, and a highly tuned absorber, but I think you could create a kind of adaptive sail, maybe even one with a kind of "standing wave" or even some wave pattern which rotates similarly to a propeller (therefore requiring less energy to sustain). Of course it seems to be highly inefficient, require massive acoustic energies, and possibly deafen any sailors onboard, but it would look really cool and may be slightly possible using some yet-unresearched [soliton physics](https://en.wikipedia.org/wiki/Soliton) ## An ionizer & electromagnet: If we could get a large concentration of ions in the air flowing through the loop, then we could apply a magnetic field perpendicular to the wind to sail on it in a very similar fashion to regular sails. Well, we can ionize the air itself using something like very powerful lasers at the loop entrance (which just like the magnetic field would be invisible to the naked eye), but again this is a pretty weak effect and would probably require massive amounts of energy to produce meaningful thrust. Again this would be hazardous to any personnel on the ship, this time due to ozone poisoning, but it would look cool and might even work. ]
[Question] [ First, a bit of background. Let's say there are two real ways to power your magic in this world. For the sake of the question, I'll refer to them as "light" and "dark". Both kinds of magic are capable of the same results, at the same power. The question is about their allowed use. "Light" magic only uses your own reservoirs of energy (let's call it "mana", for the sake of the argument) and is considerably more expensive to cast, mana-wise. "Dark" magic is considerably less expensive to cast, but this is due to the fact it pulls on all the mana of everything around you when you cast it. Everyone has different levels of mana, and as such has different amounts per day. A loss of all your mana doesn't result in death, it just means you can't use any magic until your mana reserves naturally replenish over time. There is a caste-based, very religious society that completely forbids use of Dark magic, as they see it as a violation of individual sovereignty - You're using someone else's mana without permission. As such, all* use of Dark magic, no matter what the reason, is explicitly forbidden in this society.* Knowing that these people naturally tend towards systems of very defined order, what kind of society would allow use of Dark magic in this context? Clearly an anarchist would likely have no problem using it, but I'm looking for an ordered society that accepts the use of such magic, partially or completely. What kind of government would allow it? Would a religion? Clarifications: Spells can pool the mana of everyone collaboratively casting it, to cast stronger spells, if everyone willingly contributes their own mana via "light" magic. Two "light" magic users could use their mana together to cast, but it's something willingly given, rather than taken by "dark" magic. Protecting your mana from someone else's use is extremely difficult. Such a shielding spell is something that would require a massive mana base to create even a temporary shield on a single target or area. This makes such shields rather unfeasible for anyone's use other than effectively a King or the Pope. Edit 2: Based on feedback, I think 'shielding' is something that needs to be relatively cheap and easy in this world, otherwise 'dark' magic becomes more rampant. Thanks for the discussion, everyone! I believe this has been answered sufficiently. [Answer] Give your society a communal streak, like communism. Put the greater good above the individual. Your mana is there for the benefit of the whole group. I imagine Dark magic users would be government sanctioned. Perhaps a system of communions, sabbaths or other groups will be set up. Either they have a single caster with support to extend their power. Or it’s a group of specialized individuals who share their mana depending on what needs done. Maybe firefighters in your universe would be a single water mage supported by regular firefighters that lend him their mana. As it has no physical effect they could actively work as firefighters while the water mage drains them to contain the fire. The second group would be more like a team of super heroes or an army unit. They each shine in different scenarios. By pooling their resources they outperform any individual specialized enemy. And with their diverse composition they can take on many. So make your society focused on the group and not the individual. They might even see keeping your mana to yourself as selfish. If it’s government sanctioned I imagine children to be selected during their formal education. Sorted by mana reserves and talent. The ones with large pools by conscripted like ‘batteries’ for the more talented casters. In no way has this to be an evil society. They could accomplish great things. Edit: Your edit slightly reduces the differences between Dark and Light. Still I think my answer applies. It could be considered selfish to keep your mana to yourself. Another twist could be the use of prisoners as batteries. As punishment those who do wrong relinquish the right to decide what happens to their mana. See it as community service till their sentence is complete. If you give them much freedom during this time you probably want to mark them so state sanctioned casters know whom to use. [Answer] what kind of society would allow use of Dark magic in this context? Once I realized that mana was used for nothing but magic and that using other people's mana only resulted in them not being able to use magic (if, indeed they had the talent for it at all), my answer is absolutely ANY society of ANY structure could allow this with the right excuse. I do find it weird that that a caste structured society is the one that's against it. "Individual sovereignty" doesn't much come into most caste systems. Rather it's about serving the whole, and in that case, I'd bet there was someone licensed to wield dark magic. You have got to up the stakes. Because if I were running the government and the King's men were like "we need a magic shield for the King so no one can use his manna!" I would be like "Costs too much. It won't kill him or harm him in any way, he'll replenish in a day or two and we can track down the person later. The tracking spell is cheaper. Cry me a river." There must be a danger that someone tapping mana COULD, in fact, harm or kill a person if you go past a certain point, or anyone reading it will yawn and say "so what?" A highly individualistic society is more likely not to like the use of dark magic. I think in ANY society, there are going to be people who have permission to do it, because of rank or their job. I can imagine too, entire squads with ONE magic user, who uses the mana of all the others to cast, while they fight or whatever. Very effective, includes permission. Maybe a matching jewel or something so that the caster draws specifically from them instead of everyone. Here are a few contexts in any society where this may be allowed/ it might happen: For Public works: Everyone shows up to contribute mana for the magical building of the new bridge! You can say that you were part of it!(Does not have to be a bridge, can really be anything!)"See that rainbow bridge grandkids? I was just a nipper when it was built. Ain't it beautiful? There's a piece of MY manna in that bridge. I there the day it was built. There was a parade with contortionists and acrobats. They knew how to do public works in those days. Still remember the taste of the free scone they gave you. The wizard Grandor the Great did the magic. Now there was a REAL wizard." For Private Works: So, you've got to build something/make something/magic something. Take out an ad. Pay people for their time and use of mana. If it's illegal, maybe have an excuse, like, ask them to knit or something, but they know they are really there for a mana drain. Agent 007He's on a mission from the government. License to Dark Magic. Also to kill. Anyone in enemy territory could do this. You weren't using that? Were you? Anyone who isn't a mage has these useless pools of magic in them. It's not like stealing if the filthy muggles don't know how to use it. It's amazing they even notice! But back to your original question: > > I'm looking for an ordered society that accepts the use of such magic, partially or completely. What kind of government would allow it? Would a religion? > > > The context you provided is the belief in the particular society that this taboo because of the reasons you outlined. But because the actual COST is so low, it's easy to imagine a society that doesn't view it this way at all. And in fact, it's far more likely in a rigid and organized societal context. [Answer] Literally any hierarchical civilization would allow your dark magic. However, I see the usage falling into 2 categories. Benign or Malicious. Benign being more of a structured logical approach, while malicious following an adverse hierarchical relationship. IE Bureaucracy vs Feudalism. Benign Our forefathers would wonder at the luxury of our paved streets, flowing water, and organized society. But this is not free. As a citizen it is your duty to report to your designated collection center every morning for mana collection. Your contribution keeps our city running, your sacrifice keeps the darkness at bay. Welcome to utopia. Malicious The masses do not need to have a choice. It is our duty and right to keep the peasants working and in their place. Our superior magical ability is God granted, and confers on us the duty of safeguarding the usage of magic. [Answer] Almost any society would allow use of dark magic under certain circumstances. For example, it's hard to imagine that any society would disallow soldiers in battle to use dark magic. If that use drowns the magic of the enemy, all the better! Also I guess police would be allowed to use dark magic, although to a more limited extent. You mention a system of very defined order. In such a system, you'd almost certainly have ranks, with higher ranks having more permissions. That is, higher ranks would probably be allowed to use dark magic in situations where they can successfully argue it is justified, or that not using it would have done more harm. Note that such rigid organizations usually also put a high value in maintaining their defined order. Indeed, use of black magic in order to deplete the mana of the lowest ranks might be a sanctioned use, with the reasoning that those lower ranks would likely misuse their mana anyway, as they are not educated to use their mana well. The depletion of the mana of lower ranks, together with the higher power that comes from the permission to use a limited amount of dark magic by the higher ranks, would be a means to stabilize the hierarchy. Another option would be to trade mana. This of course requires that the source of mana can be decided by the caster. So a mage who needs more mana for his spell could just pay someone for the permission to use his mana. If that other person doesn't currently have a good use for his mana anyway, he will be more than willing to make it into money (he'll be willing even if he has good use for it, but even better use for the money offered). Actually, instead of trading mana for money, the mana could even be used as money. Basically you pay for services (especially magic services) by allowing the other person to use some of your mana. Of course to work well, that requires a way to detect when someone takes some of your mana, and how much he takes. [Answer] The majority of human societies throughout history have openly kept slaves, and generally have not had any kind of rules about what a person could or could not do with their slaves. Slaves could be raped, beaten, killed, or sacrificed without any problem. Most likely, then, laws would be perfectly happy with dark magic, as long as you only drew from the mana of your slaves - and that means that almost any human society would allow the use of black magic. In addition, given the benefits of this form of magic, one could see those who make the most of it becoming rulers and defining everyone else as 'slaves'. If they do not rule, they will likely instead focus on maximising their slave possessions, and on keeping one another in check. [Answer] Virtually all systems would allow this. A truly capitalist society will simply require you to get permission, and getting permission will usually require payment. This will of course lead to wage slaves giving away 99 year leases and the like, and create a lot of work for lawyers when wizard A uses mana from a non magic user who belongs to Wizard B. A hybrid capitalist/plutocracy such as modern day USA/Australia, payment may not actually happen. See the current hubbub around fracking royalties for landowners. You would likely get some 'lock the gate' style protesters (lock the chakras?) pushing to have people paid. Communism would have a tightly controlled system where you need permission from the government to use it, and need to prove it is for the greater good. Of course, the guy granting permission would be horribly corrupt. Monarchy/Feudalism/Dictatorship would allow taking the mana of anyone below you on the pecking order. A wizard acting on behalf of the King could use mana from anyone. A wizard acting on behalf of a knight could only use mana of squires or peasants. Fascism would give unchecked rights to use mana to the government, military and police. Theocracies would have people willingly lining up to give their mana away. Ideally, this would involve a village's population turning up to church so the priest can heal the sick from that village. However, muggles will have no idea how much mana is required to heal the sick, so it'll mostly be used about as fairly as when tithing lead to the construction of lots of grand churches/cathedrals, and not a lot of feeding the poor. Military and police, in all systems of government will have the right to use it without asking for permission - you wouldn't want the [blank] to win, would you? [Answer] As you outline it, magic that draws on somebody's mana is a violation of individual rights because your mana is something that is your private property. So; what if it isn't private property? You have a society with an alternate theory of mana, that treats it as a (useful!) waste product, whose creation is simply a side effect of being alive. An elephant produces much more carbon dioxide than a mouse; why does the forest care where the carbon dioxide comes from? Similarly, why does a wizard care if the mana they're using is theirs or yours or whatever? If a king and a schlemiel both produce mana, and the stuff is interchangeable, and you don't even have to do anything to make more of it beyond just continuing to breathe, where do you get off implying that this stuff is special and yours just because it came out of you? This alternate society treats mana the same way we treat water. You don't want to be dehydrated, but as long as there's water around, you aren't going to be. Next door, there's this real weirdo who refuses to drink anything but filtered and recycled body water because all other water is owned by other beings; you try to avoid making eye contact with them. [Answer] The True keys to this are to adjust the way of looking at magic from a philosophically different point of view. Magic is Power, regardless of source. It would also be critical to have the ability for the state to draw off someones mana well codified in the law. Since you specifically mentioned Dark Magic violating an individuals knights, you could actually weave it in to your criminal justice system. In the US we have it in our founding documents that no one will be denied life, liberty, or property without the due process of law. Count Mana into this. As part of the incarceration, State Sanctioned "Dark Wizards" can draw on the energy in a prison at will and without recourse. It would be done for the same reason that we don't allow inmates things like knives, guns, etc. etc. If everyone can use magic to a greater or lesser extent, denying them the ability to use magic would be the wise and sane thing to do. Draw the magic off and use it for well defined and codified projects. Water treatment, Defensive spells, sewer cleaning, whatever. [Answer] I think with the question as set, it would be almost impossible to stop the use of dark magic. Magic is power. Dark magic is less expensive (=easier?). So the first person with magical ability to grab mana from the greatest number of people will be in a position to do whatever he wants. Of course, it weakens society. The society where this happens may be a lot like a society where an addictive but damaging drug such as opium is available for pennies, or to anyone who can grow a common weed on a hidden patch of land. Might there be invaders or liberators from outside who can better resist having their mana stolen? It surely works better if dark magic is the more expensive. It takes a lot more out of its wielder, and it is horrible for those whose mana it steals who will seek revenge on the dark mage. So users of dark magic must practice on mere animals (with very little mana) and conceal their nature and abilities until the moment when they can gain the most from a single devastating strike that will leave them weak, but (they hope) the opposition dead (by, say, fireball, not total mana loss) or disorganised for long enough that the dark mage can seize absolute power. Good thing total mana loss is not fatal, or you'd be looking at necromancy, and mass human sacrifice - like the Aztec empire, except it would actually work. Yuk. ]
[Question] [ What I mean by "a school like Hogwart" is that: * students range from age 11 to about 18, with about a thousand students in total * most students live here during most of the year * it works in isolation with the rest of the world (so it has to rely on it own gymnasium for example). Assume supplies (like food, water, electricity, fuel...) are already taken care of. * students have special powers that can cause chaos (on the same scale as your average wizard student), staff may also have some * it is set in Europe, in the current times, with the place benefiting from some supernatural features that could be used to explained some eventual inconsistencies but should not alter this answer. [Answer] Let's try to make a guesstimation from first principles. There are a thousand children to be educated, supervised, nourished, and cared for. When I was at school, the basic operational group was about 25 pupils, which, in 1970s to 1980s Romania, was called a class. I don't know how this basic group of pupils is called in English, so I'll go with class. Such a class goes through a full 4 or 8 year cycle mostly together; so for example, I started at my general school in class 1st B and ended eight years later in class 8th B. Then at highschool I started in class 9th D and ended four years later in class 12th D. So, there are 1000 ÷ 25 = 40 basic groups of pupils. Since we know that a complete cycle is 8 years, this means that we have 40 ÷ 8 = 5 parallel classes in each year, Hogwarts 1st A, Hogwarts 1st B, Hogwarts 1st C, Hogwarts 1st D, Hogwarts 1st E, Hogwarts 2nd A, ..., Hogwarts 2nd E, Hogwarts 3rd A, ..., ..., Hogwarts 8th E. We need at least one teacher, professor or supervisor per class at all times during lecture and individual study hours; let's assume that the schedule is 6 lecture hours, 6 individual study hours. Since there are 40 classes attending lectures in parallel, we have at least 40 teachers or professors. Most usually, they won't do 6 hours of teching per day every day of the week, so let's multiply that with 1.5: we have a purely teaching staff of 60 teachers of professors. Some of them will have assistants or technicians; let's say maybe 30 assistants or technicians. For the individual study period we need 40 supervisors to look after the pupils. We need a little more than 40 to account for sick days, holidays, and so on. The teaching staff need secretaries to keep track of schedules, grades, lists of pupils, diplomas, payroll and so on. Where I worked back when, there were two of them for a staff of about 50; but Hogwarts is British, so we'll put 8 secretaries. Then we needs cooks to feed those 1200–1300 people, plumbers, handymen, janitors, cleaning staff. I guesstimate one cook and one cleaning person for 50 people, 1 plumber, handyman and janitor for 100 people. The school has extensive gardens, sportball fields, forests and so on. Let's put 50 gardeners, gamekeepers, field maintenance personnel. Add in a minimum security staff, at least to patrol the fence and control the gate, say three shifts of 5 people plus 5 people extra to cover for sick days, holidays, or emergencies. Finally, let's add 12 footmen and general men-at-all-works. Over and above the functional personnel the school probably has some support staff -- accountants, librarians, printers (or scribes, don't know), medical personnel, carpenters, etc. Let's say 30 support personnel. \| Type \| Number \| Observations \| \| --- \| --- \| --- \| \| Teachers or professors \| 60 \| Includes physical education instructors etc. \| \| Assistants or technicians \| 30 \| Take care of laboratory equipment, prepare experiments and so on \| \| Supervisors or proctors \| 50 \| Look after the pupils after hours \| \| Secretaries \| 8 \| Keep track of paperwork and schedules \| \| Cooks \| 25 \| Feed the pupils, teaching staff, administrative staff \| \| Cleaning staff \| 25 \| Keep clean, wash clothes \| \| Plumbers, handymen, janitors \| 40 \| Perform maintenance of the school and equiment \| \| Gardeners and other outdoorsy personnel \| 50 \| Maintain the gardens, sports fields etc. \| \| Security \| 20 \| Control the gate, patrol the fences \| \| Footmen etc. \| 12 \| Do whatever needs to be done \| \| Support personnel \| 30 \| Accountants, librarians, medical staff, etc. \| \| Total \| 350 \| People on the payroll of the school \| So that overall there are some 350 people, more or less, working for the school. Plus of course the headmaster, assistant headmaster, their secretaries and servants... And speaking of servants, it is likely in the fictional interwar English landscape depicted in the films that every professor or teacher has their own servant. [Answer] ## 300-400 staff. Most primary schools in the US average ~100 staffer per 1000 students, but American schools usually don't deal with students living on campus and kinda suck anyway. Colleges which have students live on campus average a ratio of 5 students per full time staff member, about twice the ratio a elementary school has. Staff includes everything from teachers, to administrators, custodial, security, counselors, even groundskeepers. That would give us around 200 staff. Larger primary boarding schools have a similar ratio, 5:1 again, so we are good footing here. Plus this is supposed to be a high end school so the ratio should be low. BUT... colleges and boarding schools tend to have large supporting towns around them, you say this place is very isolated. Without a supporting town a lot more things will need to be handled in house. Also around 25% of a colleges' staff are part time, which would not count in such a ratio. accounting for both these factors a number of 1.5 to 2 times the staff is more realistic, or 3 students per staff. You might argue the lack of modern technology should increase it even more, these are modern ratios, but magic should at least make up for that plus historic schools were more ok with cramming more students per class. But Remeber they are not just providing student services, since the staff has to live on campus they must be providing for as well, a professor is likely not going their own laundry and its unlikely all the staff is eating at the student cafeteria. Normally the surrounding town provides these services but that is not an option here. All regular services to all staff and student must be provided in house. If you want to use magic to account for some jobs being filled and mitigate the town issue 300 staff would not be unrealistic. Of course these are all averages. The more high end you want the school to be, the more staff it should have, the more magic takes care of menial task, the fewer it needs. Some boarding schools have ratios as low as 2 students per staff, of course those are very expensive. <https://nces.ed.gov/programs/digest/d12/tables/dt12_288.asp> <https://www.nais.org/Statistics/Documents/NAISFactsAtAGlance201112.pdf> [Answer] ## About 100 A lot of answers WAY over estimate how many staff are needed. Instead of treating this question like: how many grown men does it take to take care of a bunch of royal brats at a top crust school, I think it's better to address the school as more similar to a standard middle class boarding school since Hogwarts serves, not just the Malfoys, but also the Grangers and Weasleys of society. There is also the flawed idea in other answers that remoteness matters. This is a school of magic. The school can be 1000 miles away from anything important and still be highly connected to society via portal or teleportation spells. You also need to assume that some things will actually take less labor in this world than in our own entirely because magic can do things that technology can not. So when you look at things that magic can normally do in fantasy settings like instant healing, cleaning, repairing, etc... then it means that a magic school SHOULD take fewer staff than a muggle school of similar size and quality. Following the same Logic as the accepted answer, but doing actual research, following statistical averages, and accounting for various levels of magic, I've come up with a much more realistic table of required staff: \| Type \| Number \| Observations \| \| --- \| --- \| --- \| \| Teachers or professors \| [49-62](https://explore-education-statistics.service.gov.uk/find-statistics/school-workforce-in-england) \| Based on average teacher to student ratios in England \| \| Assistants or technicians \| [29-37](https://explore-education-statistics.service.gov.uk/find-statistics/school-workforce-in-england) \| Based on 1.69:1 teacher to assistant ratio in England \| \| Supervisors or proctors \| [0-50](https://www.boardingschools.com/why-boarding-school/faqs/) \| Most boarding schools have teachers who live on site to fill this role during after hours. So, these are rarely unique staff personnel. When they are unique staff, you generally have 1 proctor per dormitory floor which will average about a 1:20 ratio depending on the school \| \| Administrative staff \| 4-6 \| Can't find any specific sources, but based on my children's schools and relative schools sizes, this should be a principle, a VP, an 2-4 secretaries. \| \| Cooks \| [2-6](https://www.quora.com/unanswered/How-many-people-do-you-need-in-a-commercial-kitchen-to-cook-1-000-lunch) \| If 3 shifts of 5 cooks can feed a crew of 5000 on a Nimitz Aircraft Carrier which has to operate around the clock, 1000 kids can be feed by 2-3 cooks in 1-2 shifts since there would be no need for cooking while kids sleep. The key here is "modern times". Modern school cafeterias typically order pre-prepped food that just needs to be heated up and served. \| \| Cleaning staff \| [1](https://www.google.com/search?q=how%20many%20janitors%20per%20school%20in%20england&oq=how%20many%20janitors%20per%20school%20in%20england) \| Most schools only have 1-3 cleaning people depending on thier size. Since [magic makes cleanup WAY easier than anything we muggles can manage](https://www.youtube.com/watch?v=xHEMkbyXFxs), at only 1000 students, 1 custodian should be plenty. Other than maybe needing a wizard to maintain the enchantments, most cleaning could be done by animated mops, brooms, dusters, etc... or for a less togue-and-check solution, most fantasy settings have some manner of golem able that is able to perform simple manual tasks like cleaning. \| \| Plumbers, handymen, janitors \| 0-1 \| Most schools employ cleaning staff that double as general maintenance men. Again, magic makes this so much easier, that a single magic powered janitor should be plenty. The only reason to have someone more or less in this role is if your school includes lots of highly specialized magic features that takes a specialist to maintain. Then you would you maybe need a separate master of restoration magic. \| \| Gardeners and other outdoorsy personnel \| 0-1 \| In smaller schools, this is usually also the job of that 1-3 janitors. According to one of my clients who is an arborist, even very large college campuses often only employ a single full time arborist and contract out additional grounds keepers only as needed. \| \| Security \| [0-3](https://www.venturesec.co.uk/latest-news/guide-to-security-for-uk-schools) \| Many schools in England do not employ specific security personnel at all. Those that do typically only have 1 guard per shift unless they are a particularly large school. Since this is a magic school run by powerful wizards, it is likely that this school does not need any specific security personal at all... after all, why hire a defense against the dark arts teacher if you don't expect him to actually defend against the dark arts. \| \| Footmen etc. \| 0 \| Magic makes such people far less necessary. Any job of this sort should be done by golems, house elves, familiars, or some equivalent thing. \| \| Support personnel \| 1-10 \| Most schools of this size have 1 librarian and 1 nurse. The roll of nurse and accountant are typically Administrative staff that only step into these roles as needed; so, these roles may already be accounted for. Just depending your setting, you may or may not also have 1-2 IT people (or magical equivalents), 1-2 marketing people, 1-3 school councilors (maybe more if bad things happen as often as it does at Hogwarts.), etc. \| \| Special magic stuff \| 0-10 \| Because this is a school of magic, there may be extra jobs for procurement and maintenance of special magical stuff that is setting specific. \| \| Total \| 86-183 \| While this number could potentially fall just shy of 200, closer to the small end of the spectrum would be considered how many are "Needed" to run the school as the question asked. There may be a number of temp workers or outside contractors as well that come and go as needed that make the total number of people employed by the school a bit bigger, but this question is just asking about actual staff. \| [Answer] We know there are four houses, and we further know there are seven years. That's 28 distinct student groups. There is no indication from the books that House/Year groups were ever further split to manage class sizes. In fact the evidence we have is the reverse happened: classes were often filled out by combining students from separate houses, with Gryffindor taking Herbology alongside Hufflepuff, or Potions alongside Slytherin. We don't know how often this happened, but it seems as though most classes were made of students from at least two houses. We further know that students from every year took Potions and Defense against Dark Arts, but there was only one potions master or DaDA instructor. Granting these courses were always doubled up, that means those instructors had 14 teaching periods. Further allowing for some advanced-year classes to include students from all four houses, and spread across two sets of classes each week (say, MWF vs TTh), that's still at least 5-6 class periods per day for those instructors, which is rough with a full load but doable. Importantly, this tells us combining house groups for each class was not only about spreading contact and camaraderie between houses, but also something that was needed to manage course load for faculty. Later years also allowed students more academic freedom, with new options such as Muggle Studies (and presumably either smaller class sizes or, again, combing students from all four houses). This lets us push teaching faculty count back up a little, but I still think we can start from the basic House/Year group pairs as our teaching faculty estimate. Based on this, and the idea you would not want unsupervised students during the class day, I'd expect around 18-20 separate class groups. Probably fewer, but I want to set an upper bound. This means at least 18-20 faculty, and maybe as many as six additional "advanced level" adjuncts who only taught a course or two and probably lived in Hogsmeade as often as not. I further take the books at their word for the characters we meet. The only non-teaching administration/staff we ever see are Dumbledoor, Filch, Hagrid (initially), Madams Pomfrey and Hooch, and some house elves. I'm willing to accept there might be one additional human kitchen supervisor, but otherwise the indication is the head table was sufficient to seat all of the staff and faculty, and the faculty themselves, being mainly residential, took on many after-hours duties for supervision and maintenance of the facilities. That brings us to only, at most, 32 non-elf persons, plus an uncertain number of kitchen/cleaning elves. This is light for modern standards, to put it mildly. However, I think we must also accept the use of magic to reduce the need for labor. From here you could use reasonable average class size estimates multiplied by 18-20 classes in session at a time to estimate an upper boundary on the size of Hogwarts' student population, which I would put somewhere between 400 and 600, probably towards the lower and of that range. You're looking for a school with closer to 1000 students, so we can adjust from here, but I don't think it makes sense to simply scale staff linearly with student population. Faculty, yes, especially as these faculty already seem overloaded, but administration should get more efficient as an organization gets larger. Therefore, for a school of 1000 I'd suggest a count of 80 to 90, again, plus a number of house elves that is nearly impossible to guess at. Further limit the utility of magic and I expect you could reasonably increase this number if you wished. Note that I'm excluding house elves here not because they aren't "people", but because the books provided too few clues for me to make any reasonable guess for how many there were. --- As a side note, given the estimated Hogwarts population, we could further guess at an upper boundary for the population of the entire British wizard community at only around 10,000. And if one were to do so, one would probably conclude Hogwarts is not nearly large enough. In order to handle the wizard population level we've seen indicated in the books there must be more of these schools than we've been led to believe, or, perhaps, many wizarding families go entirely without formal schooling, or both. Alternatively, one could suggest there are multiple Potions Masters and DaDA instructors, and that a group of faculty follows a group of students as they age through the system. This would allow for a larger school, with more faculty and students we never meet... if only having a single DaDA instructor wasn't such a big plot point. It's something that bothers me every time I read through these books. [Answer] My answer is about 125 Staff. Edit: Due to the comment from John the answer is now 750 full time staff Reasoning: Hogwarts takes significant inspiration from the English 'Public' (Private) School system. Quick note - Private schools (where you pay to attend) in the UK are traditionally called Public schools, because originally when they were setup, they were not Clergy or Military schools, meaning that any member of the Public (who could pay) could attend. If we look at the likes of Eton - according to their website, they maintain a ratio of 8:1 - One teacher for every 8 students, they have ~1,000 students and so 125 is the answer. Edit Again, see the above - 750 full time staff. Most Public schools have a long history of Prefects assisting the Teachers with keeping order and doing chores/maintenance etc. Which would be realistic, even in a Magical/Hogwarts setting. That is the senior pupils help keep the junior pupils in order, with the teachers/staff being the more formal authority. There is a lot of history about the degrees at which this was effective - some senior prefects being downright sadistic and tyrannical and others being generally okay. [Answer] I always felt like it was based on a place like an English public school. Eton has 1300-1350 pupils and 750 staff. That is a rough ratio of 1.8 pupils to staff members. I would therefore estimate that 1000 pupils may equal about 550 staff of all types. That doesn't account for the supernatural/magical nature of the place. It might be the case that some of the jobs done by human staff would be done by 'magic'. However it might also be the case they require even more staff because it seems like an unusually deadly place by school standards. ]
[Question] [ In my universe FTL drives are easily mass manufactured and most citizens own them and use them. The FTL drives work by compressing a certain powder which then explodes, ripping open a wormhole which the ship is sucked into. The ship will enter a dimension of infinitely folded spacetime. The dimension is completely black and is shaped almost like many ant colony tunnels. Each part of the walls in the tunnel is linked to a certain place inside the galaxy, so if the ship drives itself into one of the walls at that point it appears outside of the dimension in that place. The problem is the dimension is completely black with no light at all. It’s extremely large and there is absolutely no way for the human eye to navigate this dimension safely without bumping into a wall and appearing somewhere random. When inside the dimension the ship would act like it’s just in space. There is nothing inside the dimension except the occasional debris of ships but other than that it’s very plain and empty. So engineers invented a machine that can navigate through this dimension and safely bring the ship to its destination. The question is how would it work? EDIT: for clarification the ship never actually travels at the speed of light in or out of the space time dimension. They are just called FTL drives because if done right you can literally travel thousands of light years in a matter of days, hours, or even minutes. Almost like teleportation. [Answer] Lit buoys. [![lit buoys](https://i.stack.imgur.com/9O8DB.png)](https://i.stack.imgur.com/9O8DB.png) Your dimension is kind of like boating at night. You can't see anything. It is easy to get lost. It is easy to hit shallow water. So there are lit buoys. These mark the path. Your dimension has the well travelled parts marked with buoys. They are colored lights seen from a distance and they also broadcast a radio signal with the coordinates of the light and what it looks like. The buoys use radar to detect nearby ships. The radar operates all the time but the colored light and radio signal only turn on when a ship is in proximity - this to save energy. A buoys will ask for a battery when its own battery gets weak. It is considered good form for a traveler to stop and change the battery if they find such a buoy. Civic minded travelers carry spares. Your space is big and it is possible to get out past the buoys. When people do this they often leave little buoys behind them like a trail of breadcrumbs. Out in unexplored areas it is not uncommon to run across depleted old buoys in the dark. [Answer] The simple option would be to "feel" your way through. The cheap but dangerous way would be to use some kind of projectile... shoot ahead of you and bounce a radar off the back of the projectile. When the return signal abruptly stops, you know there's a wall and the projectile shot through it. Keep shooting to map out "space" around you. It isn't necessarily very nice if there happens to be someone or something the other side of the "wall" where the projectile is exiting though. A fractionally less cheap but rather safer technique would be to use tiny drone probes that fly out ahead of you, and you watch for them suddenly vanishing. Depending on the rules of your hyperspace, you could literally feel around with a sufficiently long tethered probe, but that might not be very practical if the tunnels were very large relative to the size of the ship. [Answer] # Track the gravity. Routes are regularly worked out by drones with years of effort exploring places. When a new route is found, they stick a massive object into hyperspace, generally an asteroid, but sometimes something as large as a planet. Some people who are OK living away from people live on these asteroids permanently, offering repairs and refuels to ships. They have extremely sensitive sensors on ships which can detect this gravity. Now, new tunnels can be found even if the dimension shifts or debris blocks a tunnel. Just track the unique gravitational signal of each asteroid. [Answer] # It's just a normal radar "When inside the dimension the ship would act like it’s just in space" It's in another dimension. The distance covered in this wormhole may put your ship thousands of light years away in a matter of minutes/days to our normal world, but inside the wormhole, you aren't moving that fast relative to how fast you would be moving in normal space. ## The best example I can give is this If you know of Minecraft's nether dimension, this is basically what I mean. Every 1 block in the nether is 8 or so blocks in the normal world. You still run the same speed in both dimensions, moving 100 blocks in both dimensions takes the same amount of time. But if you move 100 blocks in the nether, and then return to the overworld, you would have moved 800 blocks. This is basically how that dimension works. So, you don't need a radar that can move faster than the speed of light, because in the warp dimension you aren't really moving that fast, you just cover a lot of distance. And I am assuming for navigation you would rely on charts and certain landmarks and maps for navigation. Like "there is a bend here in the tunnel, with a branching path that is very distinct on the radar. Travel 800m from that point left and you'll find this point to return to the normal dimension" kind of thing. [Answer] ## Your radar could use gravitational waves Radar propagates as electromagnetic ripples. In space time, a ripple consists of a periodic gravitational deviation (that is: a sinewise gradient variation in space time) which is also known as a gravitational wave. How to set it up I'd suggest to build an rotating array of gravitational wave detectors, and a gravitational wave emitter of some kind. You could e.g. generate the gravitational waves as a side effect of the Alcumbierre drive. The drive will produce some kind of exhaust, consisting of miniature space-time gradient variations, which propagate through space-time. When there's something in the way, the reflections will reach your gravitational wave detector. Its limitations.. The wave would reflect on dimensional boundaries, so you could at least chart your space and circumvent collission with these boundaries.. but look out for black holes ! these are nasty objects that would probably not be seen by this kind of radar.. as are blue giant stars for that matter, you fly into these easily, when you cross a dimensional boundary. There's something your radar cannot anticipate.. the gravitional waves do not pass dimensional folds. Take a break, look around and plan your jumps.. Gravitational waves travel with the speed of light, so when the ship is moving FTL, your waves won't return in time. This question is not science-based, maybe you could change the strategy of travel, that is take a break and look around before jumping. The rest of the jumps better be good (FTL) of course, else it won't be of any use to attempt travel FTL through space with obstacles. See also my opening comment, consider having a map and a travel plan. [Answer] ## Follow pre-established routes This answer assumes that "completely black" means that the walls of the dimension do not interact with any kind of electromagnetic radiation. Maybe objects within it are even hidden from each other, though I assume that light works at least within a ship. How do you navigate something which you cannot detect? Answer: By trial-and-error. Explorers more or less randomly move within this dimension until they eventually emerge somewhere in realspace. They take great care to log the location, direction, and velocity of their entry and exit points, as well as their exact movements within the FTL-dimension. Your people might want to use cheap drones for this. Over time, this will establish a network of known useful routes (and many more completely useless ones), which others can follow. Hopefully the structure of the FTL-dimension is at least somewhat continuous, such that small errors in navigation still mean that you are likely to end up in roughly the right place (the scale of the offset at the exit point may be orders of magnitude higher and if you are really unlucky, you bump into a wall somewhere along the way). If the wall structure is not stable over time but drifts somehow, you will need additional effort via drones to continuously maintain and update your established routes. Woe to the colony who finds itself suddenly cut off from the rest of the galaxy because all FTL-routes leading there suddenly fail. [Answer] Dust scanner You mention that the dimension is empty save for the occasional debris of other ships. The debris will provide you a path of travel, as due to the ships having exploding once upon a time or whatever ill fate has befallen them they have scattered an untold number of dust and gas particles into the void of this dimension, to float endlessly or until they bump into the dimension walls and appear somewhere in the universe. The particles will bump into each other as well, slowing themselves down as they lose the energy that was imparted to them in the initial explosion and settling down into a 'cloud' or 'atmosphere' of sorts that permeates the dimension tunnels and then it will be possible to, with the right sensitive-enough equipment, map out a path of travel by way of particle density, or even by the presence of particles at all since beyond the dimension walls the scanners would not receive any bounce-back at all and it will then be a dark zone on the particle radar. I can imagine the presence of particles, and thus flyable space within the dimension, to be represented by smears upon a screen in the shape of the tunnels while anything beyond the dimension walls on the screen will simply be dark. [![enter image description here](https://i.stack.imgur.com/izOzO.png)](https://i.stack.imgur.com/izOzO.png) Now obviously you won't be able to see beyond a turn as in the image due to the dimension wall eating up the scanner's rays or pulses or whatever you use but it does allow you to visualize the effect of a scanner being so sensitive that it picks up dust and gas and not merely large objects. The scanner will also double as a great wreckage and potential impactor detector, allowing the crew to slow down and nudge things out of the way or go around them deal with them in whatever way that is appropriate. You'll also need a rather sizable amount of collisions or fights to have occurred within this dimension for this to be viable, as without which you'll be hard-pressed to pick up much of anything. You could manually pump the dimension with gas or dust as well but such an operation will costs time and resources, possibly being like the road pavers of today. [Answer] So, thermodynamically the walls are extremely cold within hyperspace. As ships use reaction drives, they'll spew out hot particles. Those particles will raise the average temperature of the tunnels. So you just have to "thrust" both forwards and backwards, and ensure that the wave of hot particles in front of you goes out far enough. Then you measure how far the hot particles in front of you reach, and that tells you if you are approaching a wall. The "forward thrust" is going to be a different kind of rocket, as you'll want it to be reasonably "wide" stream of particles (so you can see more), and (as you don't actually want to stop) you'll compensate with (narrower) thrust behind. This is going to be a lot like feeling your way around in the ocean by using bottom-sensing radar. You'll probably prefer to have maps and buoys for faster travel. The buoys can be made out of radar-reflective materials and have lights and even emit radio waves. Something like RFID, where they broadcast (or reflect) their identity when hit with sensors could also be good. Your maps would then have the buoys and known "walls" on them. You'd triangulate your position (maybe even in a GPS-like way) to figure out where you are, and only have to rely on "hot gas" radar in limited situations. Military buoys would exist that would not be reflective, and would only respond to specific cryptographic signals with cryptographic (and possibly tight-beam) responses. Moving buoys would be a way to engage in piracy; make someone not realize where a wall is, and have them drift into it. Then jump them in normal space before they can get out. As well as the buoys, you'll want to have relay stations for communication purposes. These stations would communicate using tight-beam to the next station. Post offices, stations with ships in them in hyperspace, would exist that would allow you to send messages back to normal space. As sending a ship back and forth through hyperspace transition requires certain limitations on ship design, there are going to be hyperspace-only ships that are more efficient. Similarly, you'll have specialized ships that exist only to ferry supplies over the hyperspace barrier. Some post offices could develop into railheads, with specialized hyperspace cargo carriers moving goods to the destination along well navigated routes. Hyperspace fleet carriers which again never leave hyperspace (except in extreme situations) that deploy spaceship attack craft would be one kind of military solution. There is no stealth in normal space, and there is no practical defence; in hyperspace, the walls are cover, so you can keep your capital assets "over the horizon" (behind a twist in a hypertunnel). I will assume hyperspace is hyperbolic, and the tunnels are local 3 space 1 time but are embedded in a 4+ space dimensional brane with positive curvature. This means that instead of n^3 volume at n distance, you get more than that; space is a saddle. This also means that attempting to form a ring of warning stations gets crazy exoensive. Imagine if a typical tunnel goes 1 km before forking into two. Then from any one point within 10 km there are 1000 tunnels; within 20 km 1 million, within 30 km 1 billion, within 40 km 1 trillion, and it keeps going. Building early warning along all paths becomes insanely expensive; and even exploring them all is impractical. Simply scale the branching rate to whatever level you want to make the radius of practical defence be however far you like. The average curvature of the hyoer tunnels puts a limit on hyperspace travel speed (together with engine tech limits) and how far you can see. The branching frequency as a function of travel speed and time between systems lets you know if multiple systems can form a single defensive ring, which puts geographic pressure on government sizes. [Answer] ## Intertial navigation systems and a map. Given your description of the dimension it would appear that by default humans have mapped its 'geography' because the crews obviously have a series established departure/destination points on record. (Otherwise their jumps would literally be random.) So you have a map of the dimension and probably one that is presumably being expanded as explorers try 'new departure points' and in so doing get a fix on local stellar cartography every time they emerge at a new point in 'normal' space. (Well the ones that survive do anyway.) That being the case you have the first key element: \\A map of the dimension \\ showing currently know exit points and their corresponding positions in the real universe. The second element; a very accurate (atomic clock) (at least one possibly multiple ones aboard each ship. The third element; **very sensitive and accurate sets of accelerometers and gyroscopes.** These are 'based on laser on a chip designs (which already exist and are in use). The accelerometers measure liner acceleration along the XY&Z axis on the ship. Basically (with the aid of clock ) how fast and how long you have traveled. The gyroscopes measure orientation and angular velocity (how fast a body rotates around its own center of rotation). Again with the aid of the clock the gyros let you measure the orientation of a vessel along any part of the journey from start to finish. With all three systems aboard your ship and a computer the vessel can basically track its own path through void by comparing its motion in any direction and velocity against the on-board map. No radar is required although one assumes it would be useful for takeoffs, landings and threat evasion. For extra efficiency you can also add active homing beacons at known safe exit points that act like GPS satellites and let you get a fix of your location relative to other exit points on the map. Then all your ship needs are directional radio receivers to detect their broadcasts (and maybe a beacon saying 'here I am' to other ships). [Answer] ## When it's dark, just turn on the lights The OP says the FTL dimension is completely dark, but he doesn't say anything about how the walls react to artificial light shining upon it. If they react in any way (e.g. reflect some of it), just turn on your ship's outboard lights and you can see the walls (or measure whatever reaction they give). Or if they don't react to light but to some other type of radiation (e.g. radar, but could be any type, electromagnetic or not), use that to illuminate them. If the walls are completely black, in the sense of absorbing anything that touches them (both matter and energy) without any sort of reaction, then the other answers can be used. I'll add a few more for that case here: ## Release a bottle of compressed gas and illuminate it with a laser A ship can release a cloud of gas and then use a laser beam to illuminate the expanding gas cloud to see where the gas particles disappear. If gas expanding in vacuum moves too slowly for the distances needed, you'll want to shoot particles out of some kind of particle accelerator and detect where they disappear with a laser in the same way. ## Magnetic fields In free space, magnetic field lines behave in a certain way. If magnetic fields can penetrate the walls (reaching the normal space beyond those walls) the change in the shape of space should affect the magnetic field, and be measurable by the ship generating it. If magnetic field lines do not penetrate the walls, that is also measurable and the walls would effectively repel magnets. ## Beams of electrons and positrons The ship emits two parallel (or close to parallel) beams, one of electrons and one of positrons. The electron and positrons attract each other, and when they make contact they annihilate and emit gamma rays. How far the electrons/positrons travel before contacting each other depends on their speed and the angle between the two beams, so that can be controlled by the emitting ship. By measuring the annihilation gamma rays you know that there is no wall up to that distance out. In this way you can 'feel' your way around, and it doesn't require gas that you can run out of, only energy. ]
[Question] [ Let's say in a magical world, there exists a basic cooling spell which slightly cools down an area by reducing the heat energy of everything inside it. In said world there also exists a particularly creative and capable mage that has managed to take this spell and massively compress it, reducing the effective area to a small cylinder but massively amplifying the effect in the process. A few high-level enchantments later and now this spell is attached to a handle, creating some sort of incorporeal lightsaber which cools down anything it phases through. The incorporeal part means that the conventional protection against cold won't work, this weapon is capable of directly affecting someone's internal organs. The compressed spell can't be activated for too long at a time, so it can only last for very few seconds per activation. Question is, just how effective of a weapon would this be? What would happen when this blade passes through a human being, rapidly cooling down a section of their body in their process? To summarize: * I have a magical lightsaber-like weapon * When activated, creates an incorporeal cylinder blade ~5cm in diameter and lightsaber-like in length. * Activation is limited to about 3 seconds at a time, followed by a significant recharge period of 10-15 seconds. * Anything touched by the blade's area is rapidly cooled down, say a 15C temperature drop. * How effective is this weapon against fleshy beings like humans? I'm trying to balance this so that it is an effective side-weapon when used right, but not so devastating that it's basically an instant win button. Edit log: Freezing rate changed from 40-50 C/s -> 15 C. It no longer freezes over time but a flat temperature reduction, to promote swinging instead of just sticking it at the same place for the whole duration. [Answer] For an assassin, it's indispensable The [Hypothermia](https://en.wikipedia.org/wiki/Hypothermia#Classification) datasheet on Wikipedia will be quite useful. 40-50 degrees per second means one degree in 0.02-0.025 seconds. At 35 degrees Celsius, or about 0.05 seconds in, mild hypothermia sets in. Normally the person would be shivering at that point, but things are so local and so quick, this won't have a chance to happen. At 32 degrees, or 0.1s, moderate hypothermia sets in. If you managed to hit the whole brain, it would start to not function. If your mage is an informed biologist, they might aim at a specific part of the brain. But frankly, it doesn't matter. At 28 degrees, or 0.2s, the brain straight up doesn't work. The heart also has trouble. That is, if they are being targeted. At 20 degrees, or 0.4s, there are no vital signs in the affected area. If the targeted area is in the brain, it stops working. If the targeted area is the heart, it stops working. Less than a second in, the blood in whatever area has been targeted has turned into ice. If that ice lies anywhere between the heart and the brain, the brain starts to quickly run out of oxygen. At that point, it would likely really hurt, but at that point they're already dead. If the victim is fast asleep, they might wake up at that point. Briefly. Even if you depart at that point, they're dead. And frankly, even if the blade was much slower, as long as it has enough juice to create ice in the bloodstream, it's a great way to kill somebody asleep. And a pretty decent way to kill someone who's awake but not paying attention. VIPs might know better than to stand still when their chest is mysteriously feeling cold, but a regular low-budget security guy might not. And the best part? No fingerprints on the victim, no chemicals that could be traced to the one place that sells it and you happened to be the only buyer this week, just a pair of small really frostbitten areas on the skin. On the other hand, if you happen to be the only criminal with a frostblade, that one piece of evidence might be enough to put you in jail, but your criminal syndicate should have plenty of good lawyers that will cast enough doubt to, perhaps with a little bit of evidence fuzzing, get you out scot-free. [Answer] Simply deadly There's a lot about hypothermia I could say, but in the end it doesn't really matter. At 40-50 degrees per second it is very deadly. The body and blood consists mostly of bound water. Even thought he consistency might make it more difficult, a full second would be deadly. Blood would freeze, as well as most tissue touched. This would block the blood, produce high pressures in the veins and cause internal bleeding. Together with the burn from freezing, it's already going to feel like a knife or sword into your flesh where hit even for a moment. Imagine sticking your tongue to freezing metal, then imagine this everywhere you get hit as well as internally. It's likely to kill, even though for some it might take a moment before death sets in from internal bleeding and damage. As a side weapon it is more dangerous than a normal knife. As it goes through armour and skin, you don't require force to kill. But if it's a side weapon I guess it's short ranged, making it too dangerous to use it as a main weapon. So yes, I would personally think it's a good side weapon you would only depend on as your secondary option. [Answer] I think you're dead. You cannot parry your opponent's weapon with your incorporeal frostsaber; while you are cooling part of their body with questionable effect, they are sticking a sharpened piece of steel through a vulnerable part of your anatomy which is guaranteed 100% to be damaging. I would suggest you work on icicle arrows, freezer darts, shiver spears or other ranged weapons that don't put you in such peril. Also the problem is with warm blood circulating everything heats up again pretty quickly from a 15C cooling. A weapon powerful enough to actually freeze a portion of flesh -- ideally heart or brain -- would be a more effective killer. [Answer] I do not think it would be very effective overall in a warfare situation. It depends of the situation you want to use it. At minus 40 to minus 50 F (minus 40 to minus 45 C), hypothermia can set in 5 to 7 minutes, he said. A drop in body temperature prevents critical organs from working properly — including the brain and heart, according to the Mayo Clinic. This is a problem of heat transfer between the beam/laser and the body, more specific the area that is being affected. In a classic combat situation where a swing of the sword would not last more than a second and would not have time to actually cool it off. You could have an impact if your sword would have a clean hit on the chest, around the heart area but even then if you cant keep it for all the duration and the victim is healthy and have a good metabolism than it will not do much, at max it will give him a good shock, which might be effective if you only want to incapacitate someone. And then there are other factors as the humidity in the air which would play a role or the environment. However if you can make the best out of those 3 seconds, you could pull some really nice assassination, as it will all seem as a heart attack, especially if the person in question has a fragile body. Overall I do not think it would be very effective combat wise, but I might be wrong so I encourage you to do more research on the body-heat transfer. [Answer] Do you want to make this a deadly weapon, or a secondary tool that can disable an opponent or give you an advantage? The application that immediately popped into my head would be the ability to give your target [brain freeze](https://en.wikipedia.org/wiki/Cold-stimulus_headache) at will. While not enough pain to disable an attacker, it's certainly enough of a distraction to cause them to miss an attack or to be slower to react to your attack. Your teeth contain very sensitive nerves and tissues that do not like extreme temperatures. These structures are (in normal teeth) insulated by the tooth's outer layers and only receive indirect stimulus. Your weapon appears to be able to bypass that insulation and thermally shock the sensitive nerves within. This would be an extremely effective disabling weapon. Based on personal experience with a cracked tooth (where the tooth pulp would sometimes receive direct stimulus), I can tell you that thermally shocking the inside of a tooth can cause a disabling, drop-you-to-your-knees level of pain. I don't want to imagine what it would be like if you hit a whole mouth full of teeth at the same time. You'd leave no actual damage, but could completely incapacitate an opponent for a few moments. Along that same line, your weapon allows you to bypass the body's natural insulation and provide direct thermal stimulus to all sorts of nerves that are not designed to be directly stimulated. This could make the cold significantly more painful or impactful than if the same temperature were applied to the outside of the body. The body's insulation would slow the rate at which the affected area could warm back up, potentially allowing you to keep an opponent crippled in pain through repeated applications. The human body has a number of automatic responses to [thermal shock](https://en.wikipedia.org/wiki/Cold_shock_response). Some of these can lead to hyperventilation or to a heart attack. Even the sudden temperature change of [stepping out of a hot bath into a cold room](https://www.nippon.com/en/japan-data/h00623/sudden-deaths-while-bathing-heat-shock-among-factors-estimated-to-cause-19-000-annual-fata.html) can alter your blood pressure enough to cause a fatal cardiac event. It's much less likely to kill in a healthy individual with no underlying heart problems, but it's still a possibility. For a less painful use case, wait until the target blinks and freeze their eyes shut. Their body heat will eventually melt the ice and restore their sight, but for a short while they'll be completely blind. [Answer] It would be as deadly as today's sniper rifle - i.e. one good hit = death. The only difference is that rifle works at long range and is mostly useless in melee and your weapon would be the opposite. And just like sniper rifle it would be absolutely useless in warfare, rather than assassination. Even more useless than a rifle, actually, considering difference mentioned. When your position is stormed by 100 soldiers, you'll hardly have chance and time to approach and slash each of them with your vorpalfreeze sword, while rifle would allow you to have at least some kills while opposing force is closing up. That was true for initial "50C reduction" version of question - we're 60%+ water and our usual body temperature is around 36C, so it guaranteed cooling of water inside body below its freezing point. You could just stick your sword pretty much anywhere and have affected part literally implode and rupture almost every every cell of affected area. Even hitting just limbs could be deadly thanks to great shock and clogged blood vessels. Your newer "15C reduction" version is much less deadly as it now requires precise hit into vital spot or cold enough environment to make at least outer layers of body cold enough to still reach water freezing point with "help" of your sword. [Answer] I'm going to disagree with the answers here and say it wouldn't do much, with caveats below. The main problem is that you are cooling a small volume (a 5cm diameter cylinder moving through the body). Let's say your target is 40cm thick front to back and you're slicing through them across the chest side to side, let's say 50 cm. Based on your edit, let's also say the cooling is magically instantaneous. So you've got a 3cm x 40cm x 50cm slice of the body that is at 22C instead of 37C. That's less than 5L of body volume (less than 10% of an average human) at a temperature that's at worst lukewarm or room temp, spread out across a wide-ish region and sandwiched with warm human flesh above and below. Someone with a better recollection of calorific equations can calculate the energy required to raise the temperature of 5L of water by 15C but I think it wouldn't be particularly vexing. Remember we can easily handle ice-cold liquids in our stomachs - in my pint chugging days, I could down a fridge-cold (~4C) pint in seconds (and more than one if needed). And we can breathe in big lungfuls of cold air - our body warms it up by surrounding it by warm blood and tissues, as would happen here. It's even worse in a fight, when muscle activity is probably producing a lot of excess heat, and the body is overall in "heat credit". The only caveat is the "magically instantaneous" part. There's a reason instantaneous isn't really allowed in physics. The human body deals well with gradual temperature changes of a much larger overall magnitude, but it's true (as others have pointed out) that you only find 22C internal organs in dead people. There may be some cellular changes (especially in organs that are normally well shielded from temperature changes) that occur at 22C that we don't know of - the heart's conduction may fritz, the brain may "freeze", you may have all sort of weird and unpleasant nerve stimuli as suggested by bta above. However keep in mind that donated human organs are cooled to lower temperatures than that (albeit with special preservatives/protective chemicals) and they work just fine. Also, hibernating mammals can reach ridiculously low body temperatures and wake up ok. On a worldbuilding level, it also wouldn't be hard for people to start carrying heat pads, hot cocoa flasks, exothermic reactions, fireball spells or what have you - hypothermia is a slow process, which is why it's often associated with exposure (lack of shelter and sustained heat loss), and your spell is brief. If you want to use it as a weapon, it needs to cool down to freezing (expansion, lots of shattered little cell walls, tissue goes insta-necrotic when it thaws) or slam the whole body at once. [Answer] Normal body temperature is 37 degrees Celsius. Hypothermia severe enough to cause incapacitation sets in around 28 degrees, only a 9 degree temperature loss. So on the face of it, a weapon capable of cooling anything by 15 degrees would seem at least capable of causing hypothermia severe enough to cause incapacitation. However, hypothermia is caused by a temperature loss in the entire body. Cooling just part of the body doesn't necessarily cause hypothermia, because blood flow and conduction will restore thermal equilibrium throughout the body. So if your aim is to cause incapacitating hypothermia, think about the total energy loss required, not the temperature change. A temperature change of 9 degrees over the entire body is equivalent to a change of 15 degrees over 40% of the body. Meaning, in the 3 seconds of activation time, the attacker must sweep the weapon through at least 40% of the target's body mass. Seems a little...awkward, especially if the target is resisting. Perhaps with a surprise attack from behind, it could be done. Furthermore, hypothermia happens slowly, in situations where the cold exposure is constant. Comparing the instant and temporary cooling effect of a magical weapon to hypothermia is questionable. I don't know how one could medically test this, but I suspect even with an instant cooling of the entire body to hypothermia temperatures, it takes at least a minute for the symptoms like unconscious to set in, especially when the target has just received a good dose of adrenaline from the surprise of being attacked. In that time, it's likely an otherwise healthy opponent's temperature will have significantly recovered, so you may not ever be able to render the target unconscious. At best, the weapon may cause symptoms similar to [cold shock](https://en.wikipedia.org/wiki/Cold_shock_response). It would be surprising, and perhaps confusing if it's not a common item. And chilling of the muscles will certainly impair the opponent's coordination and speed. But it seems to me there are non-magical weapons that are far more effective at incapacitating an opponent with a surprise attack. Like, a rock to the head. Furthermore, rocks, knives, and crowbars are not subject to any "recharging period" and they are easier to obtain. In short, seems like a pretty silly weapon to me, unless your objective is specifically non-lethal. Even then, you'll need a reason why it would be preferable to existing non-magical weapons like tasers, baton rounds, or pepper spray which are easier to use, have longer range, etc. [Answer] If we go by the high number of -50 C/s and a maximum time of 3s, we get a temperature change of around -150C. The human body has huge parts which are more or less liquid. Such as the blood. Lets look at blood first. Blood freezes at around -2 to -3 degrees C. So it becomes solid. And as everything, the blood will expand. But for that, we have to look at the whole body. Almost everything in the path of the wand will solidify pretty much instantly. And thus expand. There isn't really much to say about what will happen. Everything that freezes expands to, depending on what it is, a few times its original volume. So my best guess is that the affected area would just sort of "explode". Even if you just apply the force for a sec or so, everything is just cooled down so fast that there is really no different outcome. And I hate to be that guy, but this is a really OP weapon. Lets think about it, you can break evey lock open by just using humid air. You can disable large vehicles such as tanks or helicopters by freezing parts of their engine, thus blowing it up. There is no armor against it as it will just sort of blow up. What is so OP about the weapon is the speed. 3 sec is not long enough to react. If you made it 3 min or so to cool down to -150 C, it would be fairish. But still really OP. [Answer] It would be discomforting. 15C drop will barely even be noticeable. Even 60C will do almost nothing. A quick search tells me a 16oz bottle of water takes 1.5 hours to freeze in a typical freezer. My freezer typically shows a temperature of -20C, giving us around a 60C difference. I can hold that frozen bottle of water with no damage for more than enough time to retrieve a weapon and fight off an attacker. More evidence that it will not be effective comes from a search on times for hypothermia to set in. In freezing water it can take 30 minutes to 90 minutes for hypothermia to set in. <https://youtu.be/jnsDdJwW-KU> This video shows a man holding liquid nitrogen in his hand till a small spot freezes. What was interesting, is that it only takes a second or two to return pretty much to normal. Liquid is -195C. For your weapon to do anything, you will need it to be a much greater differential than 60C. As the question is stated, it currently cools by 15C in a small area and is inactive a considerable percentage of time. In the inactive time, the body will heat up a bit. Since it is a swinging weapon I would picture this being used against an active combatant. If they are not, why not just directly target a critical body part rather than concentrating the cold into a weapon. I picture a person with a sword being able to slay the person with the ice lightsaber since it will take too long to kill. You won't freeze any part since that would take multiple strikes at the same location and in active combat the body will be warming itself. [Answer] Another angle to look at might be frostbite. It happens at about -4 C at which it's effectively destroyed. Body temperature starts at about 36 C, so that takes about 3 seconds of exposure. A typical sword seems more effective if targeted at limbs. It should cause serious organ damage, maybe better than a stab to the brain or lungs would. The difference is how cooling one portion would affect the rest of the body, but I suppose the effect would be similar to bleeding. It seems like something to use as anti-armor rather than a conventional weapon. [Answer] It depends on the part of the body that's suddenly cooled. Several of the other answers consider what would happen if the external temperature was lowered by 15 °C, but the weapon is able to cool down the internal tissues - almost instantly delivering the effect of being plunged in ice-cold water for several minutes. On the one hand the effect is not as bad because the cooled volume is way smaller. On the other hand, the organism has had no time at all to adapt. You have warm tissues next to cold tissues, "expecting" the cold tissues to perform when they just won't be able to. White muscles (bowels, stomach, etc.) - not very much damage happens. The cold will trigger the normal pain reflex, which in the case of the abdomen can be crippling. A seasoned warrior might be able to withstand it. Striated muscles (arms, legs, shoulders, belly, back): the muscle will seize, possibly damaging itself in the process. Severe muscle pain. Massive vasoconstriction, followed by very painful restoration of function. Heart: don't know, but arhythmia is a definite possibility, and I wouldn't rule out a heart attack. It's one thing for a transplanted heart at rest to be slowly cooled down; it's a completely different thing for a heart in the heat of the battle. Brain and, more than that, the blood vessels therein: immediate loss of consciousness, very likely instant death or loss of brain function (possibly recoverable, possibly not. This would be the equivalent of diffuse axonal damage). The vasoconstriction/dilation effect would be painful in the extreme, similar to hemicrania - you get a taste of that if you cool down the sphenopalatine ganglia with ice or very cold drinks: as soon as the vasodilation starts, the whole meningeal network starts signaling pain. This happens with a localized cooling down of about 8-10 °C and a significant thermal mass behind. With a cooling down of double that and a cooled down volume behind to reduce the overall thermal mass, the pain might be enough to cause loss of consciousness by itself. Lungs: oxygen solubility in affected tissues would change by as much as 30%, which would likely briefly reduce breathing capacity. Water would also condense in the lungs, stimulating a coughing fit. All in all, no great mischief here. Eyes: immediate sight loss, probably recoverable. Again, excruciating pain from the facial nerves. In fact, I believe a hit to the face would be immediately incapacitating at best, killing at worst, since it would likely also involve the brain. Chances of blood clotting are low, but blood viscosity will locally increase by as much as 25% and this might cause perfusion differentials. Little damage, but temporary loss of function, especially in already stressed tissues (e.g. muscles in battle). As I see things, the first cold strike would noticeably hamper a swordsman, rendering them vulnerable to a second and better aimed strike. After that, the victim is very much a goner, as the third strike would find a defenseless and very likely unconscious opponent. ]
[Question] [ Machine-based communication (and navigation) relies extensively on satellites. In the future, with the massification of 5G, more and more reliance will be put on satellites (e.g. the Internet of Things), with other technologies (like fiber optic) becoming less prominent. Inspired by a sci-fi movie I watched the other day, I wonder whether there is currently a technology (even if in development stage) capable of rendering the whole of Earth's satellite network useless in a fairly quick way. You would imagine this could have catastrophic consequences on Earth (and, connecting back to the sci-fi movie, would definitively give an antagonist alien race mastering that technology a significant advantage when attacking Earth). I know there are tools to do [radio jamming](https://en.wikipedia.org/wiki/Radio_jamming). However, that is still very localised (geographically as well as in terms of radio bandwidth). I'm more interested in a technology that could render the whole (Earth) network useless. [Answer] Yes, [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome) In particular: > > The Envisat satellite is a large, inactive satellite with a mass of 8,211 kg (18,102 lb) that drifts at 785 km (488 mi), an altitude where the debris environment is the greatest—two catalogued objects can be expected to pass within about 200 meters of Envisat every year—and likely to increase. It could easily become a major debris contributor from a collision during the next 150 years that it will remain in orbit. > > > It wouldn't be instantaneous but if you exploded a few suitable targets such as Envisat you could fill the relevant sections of space with destructive fragments that then cause a cascade of strikes into other targets. Space could become a very hostile environment in a few years and remain that way for decades. [Answer] All at once, none that I know of. But you can always count on the good old human party trick: # Blow it up The classical Bond's movie move is to send a few dozens missiles and take down enough of the network to accomplish your goal. Let's take GPS, for reference. GPS work with ~~geo-synchronous~~ satellites broadcasting an universal time set on an atomic clock1. It it bothers you, skip that part: > > Your device receive signals from those satellites that tell them when the satellite broadcasted it. It deduces the time each signal took to come from each satellite, thus allowing to triangulate your position (triangulate as in, you need at least 3 to pinpoint your position in space, otherwise, you end up with a sphere or a circle and it's not convenient). > > > What I'm getting at is that the system is highly dependent on its network. If you take out enough of the grid, you create at least a "no-service" zone (per Earth obscuration), or you make it completely ineffective. My guess would be that a few missiles strikes would do quite a bit of damage to your satellite network. 1 (Not sure which missiles are able to reach satellite orbit if any though. But it's well within our reach, as well as any sci-fi race bothering visiting us) Other option: # EMP This one is highly hypothetical and should be taken with lots of care. EMP (electro-magnetic pulse) is a common sci-fi trope. Basically, a very powerful electro magnetic field disrupt electronics, and it's pretty nasty on computers. I think I remember Call of Duty MWII2 used a nuke exploding in orbit to disable satellites. Now, an explosion happening into the void of space does not end up in a big ball of fire a la Death Star. If I'm not mistaken, it instead produce electro magnetic radiation (among probably other things. I'm stressing 1 on this point). Thing is, radiations and electro magnetic fields are probably something to expect in space. (Radiation is a given, EMP... maybe 3). So I wouldn't be surprised if satellites were protected against natural causes for this. But it might be worth looking into the theory. This answer does not support any kind of attempt to take down satellites and I hereby decline responsibility if anyone manage to make sense of this thoroughly uninformed ramble and somehow devise the weapons to enact it. 1: No expert here, anyone feel free to correct me if I misunderstood something / made a mistake. 2: See why I said lots of care? [sarcasm]Very reliable source for sure [/sarcasm] 3: I mean, I know there is electro magnetic radiation in space, as even Earth has an electromagnetic field. The thing is, I don't know if they are powerful enough to fry electronics. Slight disgression here, that would need to be answered by someone actually knowledgeable about this. --- Edit 1: As pointed in comments, I was mistaken about GPS using geo-synchronous satellites. Thanks to [Zeiss Ikon](https://worldbuilding.stackexchange.com/users/57454/zeiss-ikon) and [user71659](https://worldbuilding.stackexchange.com/users/44004/user71659) for their clarifications.4 Zeiss Ikon: "GPS are not geosynchronous. They're at 20,200 km, which is close to half of GEO height, and some are in highly inclined orbits rather than equatorial." user71659: "GPS is designed to be difficult to blow up by having six separate orbital planes. [...] On top of that, there's literally more GPS satellites in orbit than the system can handle. The system needs 24, it can handle 31 at the same time, and there's 40 usable. The extras are simply on standby as spares. Compare that to GLONASS which is 1 away from losing global coverage and Galileo which 4 short for global coverage (delays & a launch mishap)." It makes sense some network are designed to be robust since [GPS](https://fr.wikipedia.org/wiki/Global_Positioning_System) was originally a military project under the name Navstar GPS. Including system redundancy is done precisely to counter-act the loss of a few satellites. If we follow user71659 comment, you'd need to blow up at least 17 satellites to impede the system (to which extent, I don't know). user71659 also suggested geo comsats would be an easier target to disable. Unfortunately, I'd need a little disambiguation as a research results are numerous, so I suggest you ask directly our fellow terrorist.SE user. Furthermore, the Kessler effect have been pointed out several times in other answers. I didn't include it in mine for two reasons. First, I didn't know the name of the phenomenon at the time, though it would be an obvious byproduct of exploding satellites. Second, satellites using differents orbits at differents altitudes, I suppose it would not be "just" blowing up some satellites and would requires some maths beforehand to ensure enough remaining orbital devices would be hit in an acceptable time-frame (before the lost ones are replaced). Probability is an hard mistress though, and she commands that, if a satellite and debris have a chance to collide, they eventually will. 4: Let's give credit where it's due. [Answer] The most obvious solution is the high-altitude nuke. Watch this: <https://www.youtube.com/watch?v=KcTrOGS3TyE> Just to summarize: nuclear blast sends a lot of charged particles at hight speed away. Earth's magnetic field redirects that back-and-forth, and since moving charges means current, and alternating current induces current in wires, it kills a lot of sensitive electric stuff, including satellites, telephone lines, electric cables, and everything connected to the end of those. So there will be a lot of collateral damage, only use this if your story supports it. [Answer] ## A rocket armed with a grenade launcher and 2000 grenades There are about 2000 satellites. Therefore, just make a rocket, launch it into space, and have it start firing grenades into each satellite individually. Satellites are designed to survive radiation and vacuums, not explosions. Apparently, they are structurally very fragile to save weight. Note that you do not need to chase the satellites. That would take a lot of fuel. Instead, you can just aim the grenades at the satellites. There's (almost) no air resistance in space, so you can fire as far as your accuracy and precision permits. If you got enough cash, you could even fire or throw the grenades yourself. This would be a lot more expensive, since you need to launch a human into space and get a lot closer to the targets (since humans are not good at aiming), all on top of the tyranny of the rocket equation. However, that's a small price to pay to be the person to destroy all of Earth's satellites by dual-wielding grenade launchers in space, in my opinion. [Answer] Both the US and old USSR had anti-satellite weapons in development before agreeing a treaty to play nice in space. I don't know if the results were ever considered viable weapons but I can't believe they would have deleted the blueprints. The Chinese actually shot at one of their own satellites a few years back. So if we can do this now, then your postulated aliens with the technology to cross interstellar space should have no problems targeting a few thousand sittings ducks moving in well ordered and predictable orbits. A shotgun makes a very capable weapon in orbit, with the advantage that the pellets don't fall to ground after 50m. If you can use laser, maser, emp/x-ray bursts or even old fashioned kinetic weapons it shouldn't be an impossible task. The magazine of the A-10 Thunderbolt carried 1350 rounds, so with perfect marksmanship you'd only need 4. Actually you could afford quite a few misses! [Answer] Some well-known hypotheticals: * Have something crash into something to start the [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome). * Build a big, ground-based laser or maser and start to take potshots at satellites. The [US](https://en.wikipedia.org/wiki/Anti-satellite_weapon#U.S._programs) stopped Star Wars before it got there. The [Chinese](https://en.wikipedia.org/wiki/ASAT_program_of_China#Directed-energy_weapons) might have something like this. * Come up with a set of malware to attack the ground control and to send destructive commands, like "spend all the maneuvering fuel get onto collision course with another sat." The problem, those control systems are rather hard. [Answer] A solar flare is capable of doing just that. A strong enough one hitting the earth directly would knock out any satellite facing the sun. So while it may not hit EVERY satellite, it would get more than half - remember the satellites are high above the earth. So, if an alien race had large solar flare level technology, it would likely destroy a large portion of our satellites. Give that the majority of our space communications are over the northern hemisphere (most 1st world counties and land mass are there), this would basically destroy most of them if positioned appropriately. See for instance: <https://sciencing.com/solar-flares-affect-communication-23537.html> [Answer] Neither 5G nor IoT depend on satellites at all. Satellites are used primarily for Navigation (GPS, GLONASS) and in the public sector, television. ### What is 5G 5G is broken down into two different radio bands. * 600 MHz to 6 GHz * 24–86 GHz Anything above 2GHz(2000MHz) will be mostly blocked by hard surfaces, and have very short travel distances. Those 24GHz+ signals would be blocked by a piece of paper. ### What is IoT IoT stands for Internet of Things, its a buzzphrase commonly used to refer to devices that, pre-2010, were not connected to the internet, such as fridges, ovens, lights, televisions. IoT seems to be a large marketing point for 5G, but as we have already defined earlier, the range of high speed 5G will be no longer than wifi, and in most cases shorter. Therefore these devices would function perfectly fine on normal wifi. ### Now, lets look at what you REALLY want Can you jam every radio signal on earth? Yes, and no. Lets look at some points. * High frequency radio waves, are hard to JAM, because their range is so short, therefore the jammers range will be just as short. * Low frequency radio waves, are much easier to JAM, and this could be done by simply placing satellites surrounding the earth that broadcast waves across the entirety of the low-spectrum. Is there a way, then to jam those high frequency signals? Maybe, radiation from an extremely powerful source, could interfere with those signals. For example: The Sun. If you could find a way to remove earth's [magnetosphere](https://en.wikipedia.org/wiki/Magnetosphere), then the radiation from the sun would be enough to knock out all communications on earth, it would even interfere with hard wired links(not fiber)! Unfortunately, that also has the undesirable side effect of destroying all life on the planet, fairly quickly. :) [Answer] I suppose if your aliens can cross light years of space, they might have some as-yet-unexplained way to cause a massive solar flare or coronal mass ejection. [Answer] Since the technology stack you describe likely will depend on the Internet Protocol, it might be possible to just corrupt the routes the packages take: by targeting the Border Gateway Protocol (BGP, which is the protocol the big routers at your Internet Service Provider speak among each other to find the shortest route for a packet to its destination) from a few strategically positioned routers under your control (positioned in the logical network structure, not necessarily physically). Even though the satellites are not routers, they form one possible link between routers ... and in the scenario you describe, they may as well have become routers. Side note: I think here's a flaw in your story: satellites will not become the most prominent data link, just because they are so far away from earth. The light speed is a hard limit and data will take considerably more time to go over a satellite link than a cable. It really is no fun to play a fast game via satellite link just because of a two-way latency ("ping time") of at least 690ms (see <http://www.dslreports.com/faq/2001>). But okay, let's set that aside for your story. The gist of the attack would be to advertise on the lower network layers (where BGP is spoken) that you have got the shortest route to every destination, therefore persuading all routers not under your control to send all packets via your routers ... where you can drop them into nirvana. This has happened already, see e.g. <https://www.securityweek.com/google-services-inaccessible-due-bgp-leak> -- a Nigerian Internet Service Provider blocked not only their own users from using Google, but blocked wide parts of the internet by advertising that the shortest routes to Googles servers are through Russia, Nigeria and China. There are countermeasures that could be taken, but these are, in essence, manual: other router admins have to mark the routers where the problematic BGP data originate from as untrustworthy. Now, if you have enough big routers under your control (your own, hacked by you, however you gained control...), you might be able to pull this off for an extended period of time, essentially dividing the network of networks that the internet is into single networks that cannot communicate with each other anymore. Disclaimer: I'm only a computer scientist, not a network security engineer. I recommend to fact-check this story on an SE about network security. ]
[Question] [ Let's not delve into specific genuses, families, orders etc. Broaden your definition of "classifications" to words like "mammal" or "fish", "crustacean" or "avian". --- Science fiction depictions of species often resemble Earthlike categories - there will be some variation of a mammal, or some slightly altered fish, or maybe crabs with an extra pair of arms - but generally these categories (classes, etc) are adhered to. --- Is there a good reason for this, or are there scientifically plausible, drastically different "categories" of organisms that evolution may produce? [Answer] Some classification systems are logically exhaustive. Like if I say that I will divide all numbers into "those divisible by two" and "those not divisible by two", it's hard to see how you could have a number that doesn't fit into either category. Either it divides by two or it doesn't. Some attributes used to classify living things are like that. For example, we have vertebrates -- creatures with a skeleton -- and invertebrates -- creatures without a skeleton. It has a skeleton or it doesn't. That would seem to be all the possibilities. But many, probably most, classifications of living things are not of that sort. We talk about some animals reproducing by bearing young alive, others laying eggs, and others budding. It's not at all clear that those are the only three possibilities. (As I write this, I'm thinking to myself, did I miss any?) We talk about creatures that get oxygen from the air with lungs and creatures that get oxygen from the water with gills. Might there not be other possible ways to get oxygen? Or might there not be creatures that do not need oxygen to live? All living things on Earth are built around the chemistry of carbon and oxygen. Science fiction writers have long speculated about the possibility of creatures with chemistry built around silicon and fluorine instead. Is it possible? I don't know. I don't think anyone has proven it's impossible. [Answer] Because we haven't found anything that can't be classified this way. If we do, or if more information about currently classified organisms is found, that puts them outside our structure, we make a new classification and slot them in there. E.g., somewhat recently, [Archaea](https://en.wikipedia.org/wiki/Archaea) were given their own kingdom, whereas they were previously classified as bacteria. Sci-fi writers tend to use existing structures, since otherwise they would have to develop entire new evolutionary paths of multiple species and work out the relationships within an entire ecosystem, for something that is merely incidental to the story, which is either adventure or drama, usually involving human(-oid) protagonists. Much easier to simply take an existing species, add in the changes you want and stick in in your story, with the advantage that your reader can follow along without having to get a PhD in biology. [Answer] Barring panspermia, ANY alien organism is going to fit in a "none of the above" category, because classification depends on descent from common ancestors - the "Tree of Life", in other words: <http://www.tolweb.org/tree/> That said, it is quite possible that categories of alien life forms might closely resemble Earth categories, because similar forms are good solutions for evolutionary problems. There are many examples of such convergent evolution in Earthly life. Tuna, ichthyosaurs, and dolphins all look much alike (and submarines look rather like whales :-)) because that form solves the problem of moving efficiently in water. Birds\* resemble bats and pterosaurs, because of the aerodynamic constraints of flying. So we'd expect to find alien 'fishoids' on any world that has oceans, 'avianoids' if alien life has developed flight, and so on. \And consider the remarkable similarity between the hummingbird and the hawk moth. [Answer] Certainly! What makes you think that all possible (rough) categories are currently present on Earth? Suppose modern birds didn’t exist, or it was a time before they evolved: would you ever think of such a thing, or consider it “different” from the other choices available? [Answer] ## Yes, There Is Plausible Scientific Reason To Expect Non-Earthly Lifeforms I think it is safe to say lifeforms are moulded by the environments in which they evolve. So, if life develops in environments significantly unlike those on Earth, the lifeforms could be expected to be equally unlike those on Earth. ## Countless Environments For Life In Our Observable Universe There are an estimated [2 trillion galaxies in the observable universe](https://www.nasa.gov/feature/goddard/2016/hubble-reveals-observable-universe-contains-10-times-more-galaxies-than-previously-thought) and an approximately [100 billion planets in our galaxy alone](https://www.nasa.gov/mission_pages/kepler/news/kepler20130103.html), each with it's own relatively unique set of environmental parameters. So, it's statistically feasible to imagine the existence of environments significantly different from those on Earth. And, any lifeforms evolving there could be equally unique. ## Many Other Dimensions Possibly Containing Unearthly Environments In addition to the nigh endless permutations of environments in our observable universe, superstring theory states there are anywhere from [10 to 26 dimensions](https://en.wikipedia.org/wiki/Superstring_theory#Number_of_superstring_theories): [![enter image description here](https://i.stack.imgur.com/UWZZY.jpg)](https://i.stack.imgur.com/UWZZY.jpg) If our 4 dimensions of spacetime (3 spatial + 1 time) hold trillions of stars, galaxies and planets, each possibly hosting life, it's possible these other dimensions could also have life-supporting environments. In a universe then where at least 10 dimensions exist, with an upward ceiling of 26* dimensions, that means there are anywhere from 7 to 19 different dimensions the nature of which we cannot even imagine easily. It is easy to imagine, though, that any life-supporting environments in those 7 to 19 dimensions could bear no resemblance to those found in our modest earthly realm of 4 dimensional spacetime. For example, if current string theory states the 7 to 19 dimensions are extremely tiny (i.e. close to the Planck limit or below it), then perhaps species capable of quantum superpositioned evolution could evolve there. And hence, any life evolving in those higher dimensional environments could easily be unlike anything humans can comprehend. ## Q Take for example [Q from Star Trek](https://en.m.wikipedia.org/wiki/Q_(Star_Trek)). Q is a member of a race called Q--a race evolved in dimensions unlike those in which humans evolved. Hence Q is unlike any lifeform humans can even comprehend: > > Q is a being who is unconstrained by, and possesses power over, normal human notions of time, space, and even reality itself – his fellow Q and he are said to be omnipotent, and he is continually evasive regarding his motivations. The name "Q" also applies to all other individuals of the Q Continuum – an alternate dimension accessible to only the Q and their guests. The true nature of the realm is said to be beyond the comprehension of "lesser beings" such as humans, therefore it is shown to humans only in ways they can understand. > > > ## Conclusion Between the myrid possible environments in our 4 dimensions of spacetime and any environments in the other 7 to 19 dimensions, I think it's plausible to expect any lifeforms living there to be as unusual as their environments are or as incomprehensible as their dimensions are, and therefore plenty of room for "none-of-the-above" lifeforms. [Answer] Aliens tend to resemble earth species because human are not very good at imagining something totally alien. Look at extinct organisms or less commonly known species and you start to see the range. organisms inherit a lot of baggage from their ancestors, our classification work for our planet's life becasue our planet's life is all connected and related which leaves identifiable patterns, those patterns do not need to be true of non earth life, certain patterns will likely be true to all life the ones not directly connected to ancestry. thing constrained by physics and chemistry would be common among all life, like how leverage works or energy intake vs output. but our classification will not apply well to life on other worlds. The phrase bounded but infinite comes to mind, there are constraints about how life works but within those "rules" there are a limitless number of variation most of which have probably not even been thought of. An example is skeletons, skeletons are helpful for increasing leverage and creating support, especially on land, but what you make them out of, whether they are inside or outside, or how they are laid out are all very flexible and vary wildly. Consider cartilage and bones, vs chitin, vs carbonate shells, vs echinoderm plates, vs wood in plants, those are all different ways of creating skeletons. You can have real fun by imagining better laid out organisms than earth life, like animals with one way breathing instead of dead end lungs, or brains that are attached to the skull at more than one point. [Answer] Why does all life on Earth fit into seven categories? Because all of it evolved from single celled organisms which formed when certain amino acids combined to form proteins, making RNA which eventually became DNA. Which was ultimately possible because (of a whole slew of things too numerous to list - some that I already skipped), out of the 94 naturally occurring elements found on this planet (and presumably, throughout the cosmos), carbon has four electrons in its outer valence shell. No evidence exists that there are non-carbon based lifeforms, and all theories that purport it does are tenuous at best. > > But now researchers have uncovered a bacterium that has five of those essential elements [out of the required six: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur] but has, in effect, replaced phosphorus with its look-alike but toxic cousin arsenic. –[washingtonpost.com](http://www.washingtonpost.com/wp-dyn/content/article/2010/12/02/AR2010120204183.html) > > > '*in effect, replaced*** phosphorus with arsenic', which means it likely acts in the same way and is merely a substitute. This bacterium is also just that, a bacteria, not something we'd call "life as we know it" in the sense that it'd be worth writing a story about it. Note also, that it does not replace carbon anyway. Even if it did, you'd have to re-write history almost completely, redefining your planet's habitable zone from the start. I almost fell asleep researching this, as the journey took me from biology, to chemistry, to astrophysics, and back again and to everything in between them all several times, when I should've just left a comment that said, because: E=MC2, evolution, Newton's and the square-cube law, metabolics, thermodynamics, photosynthesis, respiration, reproduction, social dynamics, symbiosis, and the Periodic Table. AKA, science; all of it. No matter where you go, there you are. And you are a product of your environment. If you wish to remain scientifically plausible, you cannot deviate from what science has historically shown to be the general order of things. That's why it's called science fiction, and The Tree of Life is why you can end a game of 20 Questions in 7 tries or less. Nature basically already has come up with just about everything at one point or another. It is currently estimated that there's 8.7 million species on Earth, currently, and that 99% of all species that have ever existed are now extinct. Describe something, and any biology professor worth their salt can tell you when and where it belongs. It is in my opinion, that if you can find a planet much like ours in a contemporary state of evolution, 'they' would not be so different from at least one species that you, could have, or can find on Earth. [Answer] I like Jay's answer, so I think I'll quote from it: > > Some classification systems are logically exhaustive. Like if I say that I will divide all numbers into "those divisible by two" and "those not divisible by two", it's hard to see how you could have a number that doesn't fit into either category. Either it divides by two or it doesn't. > > > ... > > > But many, probably most, classifications of living things are not of that sort. > > > This little piece from Jay's answer captures the central idea one must explore with species classification. We can often create classifications that are logically exclusive, and complete, but sometimes it just doesn't work out that way. Something worth noting is the definition of a "species." Or rather, the lack thereof. There really isn't a good definition for species in science. It's something which scientists have found useful, but haven't found a really good way of defining. It's a bit odd, really. We're taught in science class that "species" are a real thing, but in reality they are part of a taxonomy to classify nature into nice neat buckets. What you are looking for are the corner cases that start to challenge the idea that an organism can be put into such a neat taxonomy. In many cases the defining lines of species are very clear. In the case of sexually reproducing organisms, the ability to mate and produce a viable ofspring is a very effective delineation. Or is it? One interesting corner case is that of the Cicada. There are several species of cicada which are actually capable of interbreeding. However, there's a catch. These cicada emerge on strange prime numbered years. One set of species emerge on 17 year cycles, and the other emerges on 13 year cycles. Due to this, the organisms in these two species only have an opportunity to interbreed once every 221 years! Scientists put these in different "species" because of this, but we have to recognize that there's nothing physical preventing them from interbreeding -- its just temporal. Once we leave the world of sexually reproducing species, the world gets even fuzzier. It is well known that bacteria trade genetic material between species. Many species have developed immunity to antibiotics by trading genetic material with other bacteria. One may argue this is as close to "breeding" as one can get with asexual reproduction, and yet we draw lines between the species. However, we can always put the organisms into bigger buckets. While "species" may be the classification that gets the most attention, the other classifications, Life, domain, kingdom, phylum, class order, family, genus species, handle the corner cases. One might question whether M. septendecim and M. tredecim are different species (they only differ in their 13 or 17 year reproductive cycle), but both are clearly part of Magicicada, a genus which easily captures both of them. As a general rule, the higher one goes up on our taxonomy tree (towards kingdoms and domains), the harder it is not to fit in a bucket. That's intentional... it's why that taxonomy has seen such great success. It's really hard to develop a life form that doesn't fit into a domain (Bacteia -- with their particular cell membranes, Eukaryotes -- with their bacteria like membranes but lack peptidoglycan in them, and Archaeae -- which are neither), but divisions smaller than domain offer more options. When one considers the "interesting corner cases" there's no particular reason another kingdom couldn't form, we just haven't seen one. Talking to something mentioned by nzaman, we see few things breaking the mold of these lower level classifications because it's hard on the authors. It's hard to invent a brand new way of approaching life which, literally speaking, has not been thought of in the past few billion years. It's easier to stick to what we know. Also, if we stick to what's similar, it's easier to draw on existing emotions regarding those creatures. However, if you're really interested in pushing the bounds, the only limit is the scientists' willingness to invent a new taxonomical category for you. If you create something that is unique enough, we'll change our tree of life to fit. It's not cast in stone. Then again, perhaps that's what you're looking for? [Answer] Yes it's possible, in the past there exists some species that does not fit into any modern classification. For example the [Vendobionta](https://en.wikipedia.org/wiki/Ediacaran_biota) were multicellular species that cannot be classified in plants, animals or fungi. Like Vendobionta, in a past era, or in alien world, can exist lots of unknowing species that actually we are unable classify, but new categories can be created for those species. [Answer] The science of classifying organisms by a hierarchical taxonomy is called Systematic Biology. It uses all the available information of features related to the organisms in order to place them in a structure derived by evolution (taxonomic tree). That is why turtles, crocodiles and serpents are children of the class Reptilia and not to the class of grasses (not so related). Putting all these organisms together in a single tree of life it's quite difficult because we can only see living species and there are a lot of holes by lack of evidence. All alien life must satisfy the properties of our life, i.e self replication, mutations and adaptations to a changing environment (entropy). Therefore, it must follow evolutionary diversification driven by the same evolutionary forces of preserving information in an highly entropic environment. Nevertheless, as in current systematic biology, the number of orders, classes, etc can change with time as we understand more and more about our nature. Therefore, the taxonomic tree structure is NOT DEFINITIVE but it relies on evolution. [Answer] The disciplinary reason to classify exobiology into similar categories as Earth biology is because of the [convergent evolution](https://en.wikipedia.org/wiki/Convergent_evolution) principle. Creatures that evolve independently and in different environments are likely to develop similar structures if those environments are similar. For example, water creatures are likely to develop gills and fins, eventually, because those structures are so powerfully useful in water environments, and will likely retain them once evolved. There is a slightly tenuous approach to this concept in regards to exobiology: The idea that alien life would even be elementally similar to Earth life is entirely speculative. There may very well be life that is not carbon-based, or has no need for water, and we should expect this life to live in environments unlike anything on earth. Yet, in response to this criticism, if such life were possible, and say lived in a kind of methane or amonia sea, it may very well look like a fish anyway, being that it practically does live in a 'water environment'. So, continuing the example of gills and fins, we should expect to find 'gills' and 'fins' in alien creatures that live in environments that are similar to Earth's water environments, even if not elementally (save for the real possibility that our plethora of life variations is not a stupendous rarity, where something analyogous to the Cambrian Explosion marks a principally unlikely evolutionary development). [Answer] No, there is no good scientific reason for thinking that life forms on other planets would sensibly fit into categories like "fish", "insect", or whatever. People might find it easiest to describe a creature by thinking of the earthly animal it most resembles, but the only sure thing about alien life is that it will differ from earthly life in unexpected ways. The things that make mammals mammals are mostly the result of a billion years of historical accidents. There is no law of nature that associates hair with female production of a high-calorie food for infants. Many features from earthly life are likely to be found elsewhere, like skin and shells, claws and teeth. Limbs. But, if biologists ever find a world teeming with life, Linnean classification will have to start from scratch. (I think a lot of people who began their answers with "Yes" were answering a different question than the one you were asking.) ]
[Question] [ I'm currently trying to plot out a novel, the sequel to my Salamander and Brothers. Part of the plot involves a succession struggle. I mention in one of the previous books, set about fifteen years later, that the king took six months to die, so I need a disease that would be incurable but slow acting. The books are fantasies in a world that is mostly like our world but with physics sufficiently different to include magic, a craft for centuries currently becoming a science. Ordinary medicine is at something like an 18th century level, so no antibiotics and no clear understanding of the nature of disease. They do, however, have magical healers. Healers have, in effect, X-ray vision, plus some ability to affect what they see, details depending on talents and training — some healers, for example, can close a wound by weaving back together the flesh. They have a very good understanding of gross anatomy, no understanding of anything at the cellular level. One very skilled healer in a previous book knows that blood has to circulate but does not know what it actually does. I don't entirely know myself, since the different physics may to some degree result in different biology. It's pretty clearly the case, although not widely realized, that all living things have some amount of magic which is in some way connected to their life. It follows from all this that when the king, who has access to good healers, gets sick, they cannot cure him but may be able to use their abilities to ameliorate symptoms, close up sores, say. I could invent a disease but would rather use a real one, and since I don't know much about diseases I thought I would see if someone else here did and could offer a suggestion. It has to be something that would plausibly kill slowly, cannot be cured without modern medicine, ideally where the symptoms can be reduced by healers. One possibility is syphilis, which would introduce some additional plot elements, possibly but not necessarily useful, but my impression is that, treated with 18th c. medicine (mercury), it was a pretty slow killer. Tuberculosis also occurred to me. One additional possibility. It could be that the disease is one that can kill, hence is generally believed to have killed him, but that what actually happened was that he was holding steady, with the disease not cured but symptoms held down by healers to a non-lethal level, and was actually killed by poison. \_ [Answer] # Cancer Leukemia if the king is young, colorectal cancer if the king is older. If the magical healers can't affect cellular division, excising tumours would only slow things down, and would probably be too late. As a bonus, non-communicable, so no one around the king (say, his sexual partners, in the syphilis case) gets ill - just him. [Answer] An autoimmune disease. This is a category of diseases where the body misidentifies some of its own cells or parts as harmful viruses, and tries to get rid of them, essentially attacking itself in the process. Frankly these are still not well understood today, but a correlation has been suggested with cleanliness: the idea being that if you live in clean spaces all your life, your immune system never comes into contact with actual harmful bodies, and is more likely to misidentify its own bodies as harmful and attack them. Infections would be the hardest kind of disease for your healer to resolve, so a king intent on living a long time would be compelled to adopt a very clean lifestyle. He could even have commissioned spells to be created to disinfect his rooms and food, and doom himself in the process. You can play around with the idea a bit; if you always use magic for healing, then the body may develop an equivalent disease when it is not doing what the magic is doing for it. But if you want a specific example: one autoimmune disease, [lupus](https://en.wikipedia.org/wiki/Lupus), is very tricksy. The healthy cells being targeted can be of any kind, so this is still very hard to conclusively diagnose today. The disease takes years to kill a person but the early symptoms are very generic and easily missed. They include fever, malaise, joint pains, muscle pains, headaches and fatigue. All of those can be alleviated even with non-magical herbal medicine. A more distinctive symptom is [rash on the cheeks](https://en.wikipedia.org/wiki/File:Lupusfoto.jpg). But the effect may be subtle and the king could just cover it up with make-up. Other possible symptoms (don't occur in all patients) are hair loss and [Raynaud syndrome](https://en.wikipedia.org/wiki/Raynaud_syndrome), fingers discolouring when cold. In the long term, a patient suffering from lupus will develop real infections and organ failure. Then the symptoms and prognosis depend on what organ goes out first. If the [liver fails](https://en.wikipedia.org/wiki/Cirrhosis) your king will turn yellow and die in months or weeks. But the first stages are so easily missed that I think this could work for your scenario. [Answer] *Frame Challenge: It's Not* A Disease!** No, no, the king died from a curse. You mentioned a succession struggle, yes? Curses are ideal for this; if the healers can only deal with living things, they'll be helpless against dark magic (but trying their best to increase the king's lifespan). Since darkness is an element of mystery, the healers might not even know they're dealing with a curse; they might think it's just a baffling disease. The would-be successor (read: usurper) would likely the one who cursed him, or rather gained the means to curse him from a mysterious figure and/or being. But why would this mysterious character help him? Perhaps he's not; perhaps the usurper is just a pawn in his "benefactor"'s quest to finally take the throne, or perhaps this character is aiding the usurper's rise to power because he can control him, allowing the man on the throne to be targeted for his monarchial actions. In essence, the helper will be the one in charge; the usurper will just be a figurehead. Or perhaps the one who cursed him doesn't care who takes the throne; they just want revenge against the king. In this case, it'd be someone he wronged (someone who can say to the king "You took everything from me!") and ends up being killed by. In this case, I think the curse would be leeching away the king's very essence....think "You took everything from me, so I'm taking everything from you!" Now, the wronged party may be satisfied with absorbing the king's very soul, but then again, he may not. Perhaps he or she wants to be the man or woman in charge, with all the power, all the gold....it's a distinct possibility. The wronged party may even have to fight against the rightful successor and the scheming, would-be usurper, creating the power struggle you so desire. The wronged party could even be more moral than the king, or desire to put a more moral person (themself) in charge. Perhaps they only wanted revenge, they didn't realize that they had been given a lethal curse instead of a tormenting spell. In the end, it's your call, but I hope this helps. [Answer] ### Sepsis Your king got a splinter that became infected, and the infection got into the bloodstream. This has been killing people for millennia, and still with modern medicine the odds of survival are around 50%. Usually sepsis is much faster acting but your army of healers keep repairing the damage, but not treating the underlying infection. [Answer] ## You could try: Genetic Prion Disease In the context of your story, these are diseases that would onset later in life, presumably after a king has already ruled for a time. There would be few if any symptoms early in life and then they would suddenly present with worsening cognitive difficulties, challenges with balance, and jerking movements. It would progress to difficulties walking, speaking, worsening depression, agitated psychosis, and possibly seizures. There is a variant called familial fatal insomnia that would have the insomnia present in the name. Eventually he would probably pass when his muscles fail, he is unable to breath and his heart stops beating from lack of oxygen. Your healers would not be able to see anything, because even with our advanced imaging we often don't see anything. The problem is from misfolded proteins at the molecular level. There is no gross abnormality of the brain or other organ systems visible from the surface or able to be found using Xrays, MRIs, CT, ultrasounds. They would be able to treat some of the associated symptoms, but it would not have any impact at all on the disease itself. Herbs for pain and low dose paralytics or muscle relaxants would work for muscle spasms and jerks, maybe the seizures when they manifest. Psychosis is likely hard to treat except by "soothing" or sedating him to the point where he is no longer bothered from the illusions and delusions from the psychosis. Soothing may also be helpful for the mood issues, which often present as anxiety or depression. Most variants fit your "6 month" timeline perfectly. The disease follows an autosomal dominant inheritance pattern which means that it runs in families and a child that has an affected parent would have a 50% chance of getting the disease as an adult. There would be the possibility of revealing infidelity significantly after the fact by having a child that has the disease when neither parent did have it (which would be practically impossible). Given that it is inheritable with variability in how long it takes to progress from mild cognitive impairment (which may not be readily apparent to observers) to progressive severe disease, you also have the possibility of having an aristocracy where it is not uncommon for individuals in power to literally fall mad. Strange behaviour would then cause significant stress on everyone due to the uncertainty of whether an individual has had a sudden change of heart, is being progressive, radical, or is literally going crazy. People can become quite aggressive during psychotic episodes with delusions that something is true which is demonstrably false, or hallucinations of things being present that nobody else can see. I'm sure can be integrated without too much imagination. Wow that is depressing. From [GeneReviews](https://www.ncbi.nlm.nih.gov/books/NBK1229/), which is a reliable source for clinical information on these diseases: > > Genetic prion disease generally manifests with cognitive difficulties, ataxia, and myoclonus (abrupt jerking movements of muscle groups and/or entire limbs). The order of appearance and/or predominance of these features and other associated neurologic and psychiatric findings vary. The three major phenotypes of genetic prion disease are genetic Creutzfeldt-Jakob disease (gCJD), fatal familial insomnia (FFI), and Gerstmann-Sträussler-Scheinker (GSS) syndrome. Although these phenotypes display overlapping clinical and pathologic features, recognition of these phenotypes can be useful when providing affected individuals and their families with information about the expected clinical course. The age at onset typically ranges from ages 50 to 60 years. The disease course ranges from a few months in gCJD and FFI to a few (up to 4, and in rare cases up to 10) years in GSS syndrome. > > > > > The advanced disease stage is characterized by rapid involuntary muscle jerks (myoclonus), muscle stiffness (either rigidity or spasticity), and ataxia. The median survival following disease onset is six months. > > > [Answer] Mercury Poisoning A single exposure to a small amount of an organic mercury compound can be fatal in around that time frame (note: metallic mercury is not easily absorbed by the body and would not work). What happens is that the mercury bonds with selenium in the body, which is part of some key enzymes necessary for repairing damages to the neural system. When they stop working, the neural system eventually breaks down. Citing from the tragic real world fate of [Prof. Karen Wetterhahn](https://en.wikipedia.org/wiki/Karen_Wetterhahn): > > Wetterhahn would recall that she had spilled several drops of dimethylmercury from the tip of a pipette onto her latex-gloved hand. Not believing herself in any immediate danger, as she was taking all recommended precautions, she proceeded to clean up the area prior to removing her protective clothing. However, tests later revealed that dimethylmercury can, in fact, rapidly permeate different kinds of latex gloves and enter the skin within about 15 seconds. > > > > > Approximately three months after the initial accident Wetterhahn began experiencing brief episodes of abdominal discomfort and noted significant weight loss. The more distinctive neurological symptoms of mercury poisoning, including loss of balance and slurred speech, appeared in January 1997, five months after the accident. > > > > > Wetterhahn was removed from life support and died on June 8, 1997, less than a year after her initial exposure. > > > [Answer] [Arsenic poisoning](https://en.wikipedia.org/wiki/Arsenic_poisoning), whether deliberate or accidental. If accidental, the king may be drinking water, specifically reserved for him from a newly discovered spring or well that is naturally contaminated by very high levels of [arsenic](https://duckduckgo.com/?t=ffnt&q=arsenic%20poisoning&atb=v246-1&iax=images&ia=images). [![enter image description here](https://i.stack.imgur.com/SG4Ak.jpg)](https://i.stack.imgur.com/SG4Ak.jpg) [![enter image description here](https://i.stack.imgur.com/pd0xB.jpg)](https://i.stack.imgur.com/pd0xB.jpg) [Answer] Pancreatic cancer Even with modern medicine, this is something you are unlikely to survive as it usually shows no symptoms until it is very advanced. Six months is quite plausible. [Answer] A combination of age related diseases It's exactly this that happened to [Timo Sarpaneva](https://en.wikipedia.org/wiki/Timo_Sarpaneva), a famous Finnish designer. His state started with vascular dementia but he also got Alzheimer's and Lewy Body disease on top of that. In his case, especially the last year was difficult based on a documentary I saw so I imagine you could scale that to half a year. It would be a natural option especially if the king is old. [Answer] 18th century medicine? Tuberculosis. AKA the White Death. On the one hand, people in dry climates have been known to last for years with TB. On the other hand, a 1994 study in Baltimore had time to death for those who died (most survived) of 39 days. These were generally immuno-compromised, but the two numbers bracket 6 months pretty well. ]
[Question] [ For a civilization that depends heavily on canals for transportation, what limits are there on how steep canals can before they flow too fast to traverse? I know that barges were normally pulled by animals upriver, if winds were unfavorable, so would the maximum slope of the canal depend on how strong the beasts of burden are? It would be neat to be able to calculate the slope in like meters dropped per kilometer in a general sense. [Answer] A canal with a gradient and a flow is a river. And navigatable rivers are pretty much flat. Taking a nearby river (the Medway) and measuring the change in height from the coast to the point at which it becomes essentially unnavigatable gives an average gradient of 0.0003 or about 30cm per kilometer. Wider rivers have lower gradients. The Mississippi has a gradient of about [1cm per km,](https://www.researchgate.net/figure/The-Mississippi-River-gradient-plotted-between-New-Orleans-and-Head-of-Passes-the-site_fig4_222406982) yet still flows pretty quickly If you have a flowing canal, you need a constant source of water. This is why canals use locks. Don't design canals as rivers, unless you already have a river to redirect through it. [Answer] > > The Suez Canal is an artificial waterway of about 190 km in length running across the Isthmus of Suez in northeastern Egypt which connects the Mediterranean Seas with the Gulf of Suez, an arm of the Red Sea. It has no locks, because the Mediterranean Sea and the Gulf of Suez have roughly the same water level and is thus the world's longest canal without locks. ([Source](https://books.google.com/books?id=WeocAAAAQBAJ&pg=PA35&lpg=PA35&dq=%22longest+canal+without+locks%22&source=bl&ots=6N-yAp7iED&sig=ACfU3U3_tQk9O2mmCAf50D9__arNRlYGow&hl=en&sa=X&ved=2ahUKEwjEqdHI-MHhAhXpoYMKHXoODPYQ6AEwAnoECAkQAQ#v=onepage&q=%22longest%20canal%20without%20locks%22&f=false)) > > > Karakum Canal without locks in Russia is the longest canal in the world with a total length of 1400 kilometer. It was built in 1954 and completed in 1967 having a length of 840 kilometers and further extended in 1970 and 80s up to Caspian Sea coast making its total length of 1400 kilometers. ([Source](http://allpaedia.com/mobile/general-knowledge/longest-in-the-world/3129-longest-canal-in-the-world.html)) > > > To answer your question, 0°. The differences in "sea level altitude" between the sources and destinations of these bodies varies naturally according to the tide, but the canals are dug such that those variations are accommodated within the canal — which can only be done when the source and destination altitudes are fundamentally equal. There is obviously some small amount of ascent/descent or the canals/rivers used for cargo transport wouldn't have a current. But that ascent/descent need not (and almost always is not) a condition of the path being traveled by the cargo ships. For example, the Mississippi has nearly all of its descent in its northern most reaches. By the time you get to the majority of shipping in the southern U.S., it's basically flat. The current is caused by water pressure from the north. [Answer] The gradient should be 0, UNLESS the high end of the canal has a flow rate high enough to compensate for the amount of water being drained from it by the canal into the low end. Which for any decent sized canal would be a lot indeed and probably make the upstream end of the canal hazardous for shipping because of the rapids. This is simple physics. Water (as any liquid really) want to establish equilibrium, meaning the surface wants to be flat and level. Thus it flows from high to low until equilibrium is established, both vessels having the same water level. The only way to thus have a canal with one end higher than the other without an artificial barrier (a lock) in it is to ensure that the high end gains water as fast as the canal can drain it. In theory of course you could calculate the exact drainage and pump water out of the low end at that rate, back into the high end. But locks would be much easier, cheaper, and more reliable. [Answer] Your only limiter is how much your beasts of burden can drag up river. This is less dependent on slope than it is on the speed of flow and shape of the hull. Personally I'd favour double hulled boats if your channel is wide enough, they cut through water pretty well while giving you width for cargo space. Whereas a similar single hull would probably need to be a long thin boat in a heavy current. [Answer] I wonder if [Tesla valve](https://www.youtube.com/watch?v=jEnHi9L0Oy8)-shaped channel would work for you. It can make flow 10-100 times slower than unimpeded one, so I guess in theory 1/10 gradient would become possible. But it works best with pulsed flow and when covered so I am not sure if it would work in this case. [Answer] If your canal empties into the [Bay of Fundy](http://bayoffundytourism.com/worlds-highest-tides/), you've got fifty feet of vertical displacement to work with, thanks to the tides. You can achieve whatever angle you might fancy by varying the length of your canal. ]
[Question] [ In my story, a team of scientists are sent to an alien world similar to Earth to conduct general research on its environment, ecosystem (that is: its animal- and plant-life), and weather. It is the first visit to that world. My question is this: what kind of scientists would be sent on such an expedition to an alien world? [Answer] There are two different questions here: First question: Which scientists are needed on the expedition? Clearly, competition for space on the exploration ship will be intense. Expect battles, backbiting, politicking, and all manner of behavior unbecoming scientists. To make it even worse, some specialties require a lot of gear (mass spectrometers, autoclaves, you name it). There will be howling when several scientists (~180 lbs each) get bumped in favor of a backup mass spectrometer... First tier might be ones you absolutely know you'll need to study the planet proper and the space around it Geologists, weather scientists, chemists, physicists, astrophysicists. Then ones you'd feel better not omitting, in case there's life there: Biologists, biochemists Then, hoping against hope: Linguists, sociologists (maybe culturologist/anthropologist instead) Second question: Which scientists will try to bully their way onto the spaceship? All of them. [Answer] biologists and geologists mostly, of a variety of subdisciplines but no one too specialized at the same time, you want people who know how to take samples correctly and how to assess comparative value of samples, and can work with may aspects of the field equally well. Like Nasa missions there will be a lot of cross training, you are never just an expert in one field. The more expertise you can pack in each brain the better. That said overspecialization makes you useless. This is especially true for biologists since right now we only have earth life to study. Your scientists need a broad base. A botanist for instance would be less useful than a general biologist (of equal quality) since whatever is fulfilling the plant like niches is unrelated to earth plants and thus will not mesh well with the assumptions a specialist is used to working with. Likewise a geneticist will be useless if the life there does not use nucleic acids, but would be very helpful if it does, so you should decide if they go in with any information. This is also affected by how much room you have, and if you know anything about the planet before you go, if you already know it has life for instance biologists become a lot more important and you will want many of them. Exo-geologists have to understand a lot about many different aspects of geology since many of the familiar rules of geology change on different planets. So you want at least one geochemist, and one exo-geologist at bare minimum. geology is less troubled by specialization since, for instance, volcanoes are volcanoes no matter which planet they are on, so if you have space for a volcanologist bring one. biochemists, these are the people who will be doing the initial analysis of many samples so you you are going for an extended visit you want some along. for short visit they are less necessary, although would be a helpful bonus if there is space, and a must have for cross-training. Paleontologists,mostly as cross training, that gives them an advantage with dealing with unexpected ecosystems, and you really want someone looking for fossils. A Planetary climatologist although for the most part they can work remotely provided you have decent satellites, but if you have room or are staying for a while definitely bring one, they will end up working with the geologists a lot. Even for a shorter visit you definitely want some cross training for this to take some ice cores if possible. If the planet has oceans, a oceanologist would be a must have, with the same specialization caveat as the biologists. A medical expert will be important not just for normal mission needs but also for understanding how the world affects your explorers, this is especially important for longer missions. Ideally you want to release a lot of satellites and remote drones/propes so you cover a lot of land. Even more ideally you want satellite map before you even plan on landing, so you know where the most interesting looking things are. No expedition would be sent to a planet that had not been heavily observed by remote/satellite means or without a map of at least the majority of the planet's surface. Note I am assuming we are talking about people on the landing mission, there may well be other scientists in a orbital ship, ones who are not concerned with the planets surface, of who can work better remotely. [Answer] No scientists on the first trip. Astronauts. Consider [Skylab2](https://en.wikipedia.org/wiki/Skylab_2). The astronauts did science experiments up there. But these were experiments that had been teed up for them - they could follow the recipes and collect the data, which the real scientists on Earth could then argue about and minutely dissect. The astronauts were not following the questions where they led them. The main thing for the Skylab2 crew is that they not die and they be able to keep Skylab functioning. Pure scientists are a rarefied bunch. These are the people who you want looking at your data and your specimen, thinking the big thoughts. They are not the people you want at your side as you are trying to figure out what is wrong with the lander during your descent. You want another astronaut who has been trained, vetted, spun around, stressed out and whom you can count on to keep you all alive and safely returning home at the end of the mission. On this sort of first contact thing you need versatile generalists in excellent physical shape, excellent mental shape, and ready to follow the chain of command. Astronauts. On Skylab2 there was a physician. He was also an astronaut. If physician counts as scientist I can imagine there would be one of those along. The other thing about the science on such a trip is that it would be wide and shallow. There would be a lot of data to collect, quickly. You do not want your entomologist to spend all his time collecting small animals, and forget to take atmospheric samples and geologic samples and magnetic readings and so on. You want a generalist who will carry out all the things that are assigned to be done efficiently and as assigned, and can troubleshoot / triage along the way: an astronaut. [Answer] Let's take a step back before deciding who has to land on this planet. However advanced this civilization may be so that they succeed in sending an exploring ship to another planet, they still value human life. Therefore they are not going to land a single crew member without good chances of taking him/her back alive. And until disproved, any unexplored environment is hostile. Step 1 would be deploying a set of satellites to investigate the climate and surface morphology of the planet, to determine local condition and potential hazards. Main goal would be to isolate the best location for first contact with the planet environment, if present. Step 2 would be sending remotely controlled drones, to determine local chemistry and conditions (is atmosphere breathable? Are there known dangerous chemicals in the environment? How is the local flora and fauna?) Mind that both previous steps can be highly automated, with expert systems analyzing the bonanza of collected data. Moreover, you don't need a Ph.D in biology to tell that that furry headed pussy with large claws and fangs who is jumping to catch the drone is a threat to humans. Then, once the local conditions are better known, you can train the people on the spot based on the findings. They don't necessarily need to be top notch experts, they need to know what to do to integrate the data already collected by the automated systems. The topics on which they would need to be trained are: * biology (botanic and zoology) * geology Since they would need to be able to operate and maintain satellites and drone, I expect them to be already skilled in engineering (mechanic, electronic). Side note: the Apollo astronauts got an intensive training in geology before their missions, so that they could tell which rocks were meaningful to be taken back home. [Answer] What scientists? The real question is what is the mission? A mission of scientific research to an alien world is too broad, the entire scientific community would want in on that. The better way to go about this is what is the objective of the research? To that end I postulate this: With the advance of Genetic Engineering the GE community would be hungry for extra terrestrial biological solutions (adaptations). Ground teams are expensive so few can go who do you send? * Advanced biologists- being able to quickly identify, evaluate, and scientifically prioritize critical subjects for capture and research is mission critical. Candidates here must be versed in biology of course but also chemistry and genetics (which aren't completely dethatched fields). These additional disciplines are required of each candidate in order to better full fill their ultimate function of finding the most valuable specimens. * Trappers - Though not a scientist, highly skilled individuals in the understanding of animal behavior, combat, and trapping (usually not taught in academia). With the amount of education required of the advanced biologist, there would be critical need for a more expendable individuals who can assume the risk of capturing dangerous organisms. General biology would be helpful for these candidates in order to better communicate with the advanced biologist. * A (1 - 2) Microbiologist - Microbiology would be another critical ecosystem to explore however due to the magnitude of its search area this would not be the initial focus. These individuals would be more dedicated to ensuring health, safety, and proper containment protocols are met. Ensuring that ours and their microbes do not cross contaminate. Providing medical expertise in the event of an emergency or contamination. Candidates need to be specialized in microbiology, pathology, medicine, and surgery. When not serving their primary role they would be expected to try and collect specimens for research. (These would arguably be the most difficult to find as they would have the most diverse collection of specific specialized knowledge, they are however not improbable). * A Technician - An expedition such as this would undoubtedly be heavily burdened with technology. Someone would need to be present who can repair and maintain said technology in the case of failure. When not performing said primary function they could also serve as a comm officer and quarter master. Piloting skills would also be advantageous as they would likely stay with the ground ship/ base camp. Required disciplines: Mechanic, Electrical, and even software engineering would be required. Some bonus disciplines would increase candidates chances: * vetenary medicine: Vets are trained in adaptive inter-species medicine. Having this experience would be useful in assisting biologists or preserving specimens. Its not required as advanced biologists and the microbiologists could wing their way around this as far as the ground team is concerned. * military experience: responsiveness to command and threat recognition would be advantageous as well as experience in operating firearms. Weapons would be brought as there is no telling how aggressive the fauna or even flora will be. * Geology: would be nice to have this skill in addition to others as it can help biologists find more interesting biomes. It can also add some useful research data and cautionary insight. However satellites can develop more/better geological data than a single isolated geologist. Unnecessary Experts: * Geologists: An alien world with life and you want to send a geologist, \\\\ no! Rocks are nice and all but life is more interesting. A large chunk of geology can be better handled by orbital sensors from a satellite and interpreted elsewhere by geologists. * Meteorologists: completely useless. A pre-programmed satellite could effectively provide this function as well as collect effective enough data to be later analyzed by said experts elsewhere. * Pilot: Automation could easily replace this role as well as other specialists could be trained as an effective enough redundancy. + Chemists: Can be replaced by technology. However they will be among the army of eager scientists awaiting the return of samples and data. + Oceanology's: This specialty would be ok to have but initial trips would likely avoid in-depth oceanic research as it requires more hardware and initially can be largely and effectively enough handled by the advanced biologist and orbital censors. * Paleontologists: Would also be unnecessary. The focus of initial trips would be the living life. Once that's thoroughly explored maybe they will care enough about what existed before it. Not to undermine the field of paleontology but it takes an obvious back seat in priority. * Biochemists & Geneticists: Too specialized for this trip. likely they would be among the army of scientists awaiting the data. * Botanist: Botanists are overly specialized more in terrestrial flora. Ideally you would want a more generalized field like biology over this. * Linguists: would be a gamble. Life can be detected with a probe but intelligent life isn't necessarily so easy to detect. Sending a linguist solely on the hope that intelligent life is present is a bit of a stretch especially because if there isn't any you have a completely wasted seat. Early explorers were capable of establishing basic communication with natives and initially if intelligent life was discovered I suspect they would put faith in their intelligent people figuring something out. So this specialist would likely come in subsequent missions. Summation: Competition would be high, however resources would be limited and educational requirements would be high as well. Technology would greatly reduce the need for various on the ground disciplines. With such limited space the hirer would have first pick and would likely pick people who have the most diverse critical skills to reduce team size requirements. Basically it would be a game of how much science can you extract with as few people possible. The critical approach to this is what research do you need boots on the ground to conduct versus what can you get from automated censors because you can always collect things to bring back to an army of researchers. [Answer] Do you know for sure that there is plant and animal life on that planet? Most planets won't have any, so anyone following up on that will be on the second trip. The first trip has three main concerns: getting there, staying alive during the visit, and getting home again. Or at least getting the data home, anyway. There have been definite plans for one-way trips to Mars with little prospect of personal survival but guaranteed fame for the rest of human history, and your astronauts may ultimately be destined to die there, but they must not snuff it until they've sent data back to prepare for the next mission. With that in mind, it gives you a very short list of scientists... *None at all.* Every crew member on that mission will be an astronaut, dedicated to getting the spacecraft there and keeping it running during the mission. Some (most?) may have a science or engineering background, but this will very much be a secondary concern. The science missions will be pre-planned, scripted, timed and practised on Earth. There will be absolutely zero opportunity for personal research, because a large multidisciplinary body of scientists will have decided before the mission what data is absolutely required, and will have planned priorities and scripts to ensure that data comes back, and the mission commander will be keeping their crew on script and on deadline. The very last thing you want is some eager-beaver scientist vanishing off on their own little personal tangent. This is a massive trillion-dollar enterprise, and it absolutely cannot be left to chance. So who will you get? Pretty much the crew from [The Martian](https://en.wikipedia.org/wiki/The_Martian_(Weir_novel)). All of them are talented individuals in their own right, and superb problem-solvers. All of them have some specialist areas, but all those specialist areas could be carried out competently by any other crew member. ]
[Question] [ This is the next piece in my question-series, you guys have been absolutely awesome in your answers to the first question: [How to solve the old 'gun on a spaceship' problem?](https://worldbuilding.stackexchange.com/questions/58049/how-to-solve-the-old-gun-on-a-spaceship-problem?noredirect=1#comment165749_58049) In this series, I try to find a number of questions bugging me while working out my current (awesome) project :) All answers should be plausible, but not do not need to qualify as hard-sci-fi. I am aiming for [Physics-Plus on Mohs Scale of Sci-Fi-Hardness](http://tvtropes.org/pmwiki/pmwiki.php/Mohs/PhysicsPlus) (TV-Tropes link). I am envisioning a system able to create the following effects: * General 1 G environment on space stations, space ships, orbital installations and so on. * The Gravity should not be generated by rotation (I am fairly familiar with these designs more rooted in reality) * If it can be done this 'gravity zone' should have a fairly constant feel to it, but a small 'gradient' is ok too. * The field should be fairly well defined in its dimensions. *In Units of handwavium (UHV\), which is the cheapest way of achieving this?** Further notes: * Form can follow function, so if a spherical field is most plausible, all spaceships can be spherical. * Weird events when two shielded entities are getting too near to each other are encouraged. * The use of kinetic weapons / missiles in ship-to-ship combat should still be possible. * The used solution should have the least possible implications. For Example: If I have complete control of gravity, I can do almost everything, right? So if there is any chance, keep it as low-tech as possible. ''Unit of Handwavium is defined by LSD/page (loss of suspension of disbelief / page)\* I am aware that some things are better left unexplained, but I strive for consistence. Thank you! [Answer] The real problem with what you are asking for is the hand wavium for artificial gravity involved super science as a minimum (how are you going to stabilize a neutronium sphere smaller than a neutron star, for example?) and insanely powerful engines to haul all that mass around. It gets worse if you try to wave your hands faster and use gravitons, or adjust the Higgs field in order to change the mass of the particles inside the field. If you can do that, why are you waving a Glock around? A beam of polarized gravitons would selectively tear the ship apart, or you could set up destructive interference between your Higgs field generator and the one on the enemy ship. Destabilizing whatever holds the neutronium sphere or plate together effectively turns the enemy ship into a Nova bomb as the neutrons fly apart at near the speed of light.... The best advise I can give you is follow the lead of shows like Star Trek, Star Wars, Firefly, Guardians of the Galaxy and dozens of other space operas and have gravity floor plates as a "given" with no special discussion of how they work at all. If you want to disable the gravity field, then the hero (or villain) cuts the power cable or sends computer malware to bolix up the computer. [Answer] Never turn the engines off. Just make sure the ship is always accelerating "up" at a constant 1G. If you want to stop manoeuvring, just flip 180 degrees and burn the other way every now and then. Cons: Requires infinite fuel, and you can't run away from anything quicker than 1G... [Answer] Super low-tech version: wind generators. We already use it for poor man's antigravity: [![enter image description here](https://i.stack.imgur.com/pcrFY.jpg)](https://i.stack.imgur.com/pcrFY.jpg) Vertical wind tunnel simulated skydiving, Erik Charlton from Menlo Park, USA (Screaming Fast) CC BY 2.0, via Wikimedia Commons Put generators on 'top', allow air flow via grid flooring: [![enter image description here](https://i.stack.imgur.com/KRbPo.jpg)](https://i.stack.imgur.com/KRbPo.jpg) Floor Metal Plate 02, Filter Forge, CC BY 2.0 I know, not really 'gravity', but hey - Nostromo wasn't any space Ferrari either. Advantage: UHV-free proposal. [Answer] Well a simple, if dangerous, way of doing it is to use real gravity. For this, you need a good supply of small black holes, and a reliable way of controlling them. But if you have those, then your ships and stations are spheres, with their black hole at their centre, and a number of spherical decks around them. Because the black hole has much less mass than a planet, you'll have detectably different strength of gravity on different decks. This will mean that your ships have very high mass, and accelerating them to high speeds is kind of difficult, but you win a few and loose a few. If you use this, may I suggest you don't explain to the reader how the gravity works, and leave them to puzzle it out. A reveal can come at the point when something goes wrong. [Answer] Here's an idea, but it may use too much handwavium: You could have a material which has radically different gravitational mass and inertial mass. For example, a material that has the inertial density of steel and the gravitational density of a white dwarf star. Then you need a decent amount (sphere with radius ~70 meters) to generate a gravitational field on the surface equal to earth's gravity. This would still give you a space craft that can accelerate fairly easily. You can tweak the gravitational density by a few orders of magnitude (neutron star density makes the required radius very small, and it's still hard to get enough to collapse into a black hole.) For context: the inertial mass of an object is it's resistance to motion, while the gravitational mass is how much it affects and is affected by the force of gravity. It was a mystery why these numbers were identical for all materials in existence until Einstein proposed that it may be because the fabric of space is moving things, not that there is a force acting on some particles. Beneficial consequence of this idea: this material can be exceedingly rare, occurring naturally, or be generated in small quantities (or large quantities) in a lab. You get some narrative flexibility using this as a plot point. Unintended consequence: if you remember that all action has an equal and opposite reaction, you might realize that this material is very hard to handle because it is much more affected by the natural gravity of planets. In particular, the force that is pulling it to the planet is dependent on it's gravitational mass, and because it is less massive than expected for that much force it will accelerate much faster (by the same factor that it's gravitational mass is higher than it's inertial mass). This could mean that all of your spaceships are drifting out away from massive bodies, if they have artificial gravity. [Answer] Magnets! Have the whole crew drink a regular dosage of liquid (non-toxic) metallic substance, and have the ship laced with powerful electro-magnets. Make sure anything else on the ship you want to be affected by gravity is metallic, or has something metal glued to it. Voila! Pros: with superconducting electronics, should be almost energy free (assuming what goes up must come down and vice versa) Cons: The metal must be evenly distributed around the body, or else you'll be pulled down by your stomach only (painful). [Answer] An alternative way to assist the suspension of disbelief, instead of giving a plausible explanation for why it works, is to instead describe in detail what it does. Describe all of its quirks and limitations. This works well narratively because everyone on the ship will know in detail what it feels like when the gravity generator is on the fritz but few will actually understand the gravitomagnetic effect it uses to bend space-time around itself. You can be creative and give it a lot of different problems. For example, in Star Trek: Enterprise, the human engineers haven't figured out how to generate a completely uniform gravity field, and there's a small space in the Enterprise where it goes the wrong direction; in one room you can jump up and sit on the ceiling. Other possibilities: Does it taper off gradually outside the ship? If it changes a lot over a short distance, large delicate objects could be snapped in two by the relative difference in gravity at each end of the object when falling out of the field. This could be particularly impractical on a smaller ship with a smaller artificial gravity field. Does it switch on instantly, dangerously throwing floating objects to the floor? Or does it take an annoyingly long time to spin up to full power? Does the field itself have significant inertia? Does it have angular momentum like a massive gyroscope? It could take a lot of extra energy to accelerate or rotate the ship when the gravity generator is on. Maybe space tugboats and space marine boarding craft don't have gravity generators, to make them nimble enough to manoeuvre around other craft. Is it physically huge, costly, or very energy intensive? It might not make practical or economic sense to include them on small vessels. If it doesn't also propel the ship, and the gravity is pointing in one direction over most of the ship, then something on the ship has to be pushed up with a force equal to the force pushing everything else down. Possibly the generator itself. Strong structural beams would have to anchor the gravity generator to every section of the ship, or the ship would fall apart. To minimise bad leverage on these beams, a very large single generator ship might be shaped like a skyscraper with the generator near the bottom. Large vessels in other shapes would need either multiple gravity generators to distribute the load across the structure, or to have gravity pointing in opposite directions in different sections of the ship. Does the gravity field's shape or strength change when the generator is rotated or accelerated? This could provide some light comedy with people spilling their coffee at one end of the ship when it turns around, or it could be a serious limitation to how fast a ship can manoeuvre with the gravity generator on without tearing itself apart. [Answer] You could use [gravitons](https://en.wikipedia.org/wiki/Graviton) like in star-trek. This would basically be using plausible particles that pass from one plate to another (works like magnetism, but with gravity!) Your second option would be a sort of 'dimensional impaler'. Basically, gravity is generated by large masses distorting space-time around itself. So you could have an device that simulates this distortion to create gravity. And the expensive option is [Neutronium](https://en.wikipedia.org/wiki/Neutronium) plates (make your ships weigh about as much as a planet) EDIT: Found the word I was looking for for 'Neutron' plate. EDIT2: I take back Neutronium as an answer as 'magic' would be less handwavium. Not only would using raw mass for gravity require something like 1.7916 × 10^17 kilograms (0.02% mass of Ceres based on comment here), But the massive gravity gradient from the lack of distance would make almost anything else more practical (especially just spinning the ship). [Answer] I'm a physics layman so this may just be provably wrong. If you could selectively over concentrate and somehow stabilize a subatomic particle that is responsible for mass maybe that could generate significant gravity in a small area at controllable rates. Like maybe you have super dense "higgs-boson concentrated plating" that acts as gravity plating? If you think it's neat you could have things in space falling toward the ships floor and require some sort of deflector device to push stuff away. I think the more controlled the gravity the more you move towards some sort of high energy speculative thing on the level of controlled wormholes. At that point I think maybe you just hand wave the whole thing and use some gravity control field that isn't explained in a ton of detail. ]
[Question] [ A speedometer is a gauge or device used for measuring instantaneous speed of moving vehicle roughly speaking, so for example the reading shown on the speedometer of a car parked at road side displays zero implying it is at stationary position respective to the road or landmark etc as long the surrounding objects are at rest relatively to ground. I believe some of you already see where this is going... Correction: This speedometer actually counts how many turns the wheel makes which then can be translated good indication of vehicle speed but not without flaw as mentioned by Michael Kjörling's comment. Another example is a speedometer or otherwise called pitometer log which is usually seen in boat or ship and I shall leave you to find out the working mechanism. (clue: differential pressure of water) I know with GPS who is still using speedometer nowadays let alone in the future but I'm sure some of you are aware of the limitations. Notes * Please factor in time dilation when you approach closer to speed of light in vaccum. (e.g. Lorentz factor: <0.9) Questions 1. How would interstellar spaceship without FTL or wrap capability measures instantaneous speed accurately? 2. If instantaneous speed is useless for space travel then what kind of measurement would be adopted instead? (e.g. light year is used instead of miles or kilometer etc.) [Answer] A spaceship could measure red/blue shift from stars around it. This would require a database of light frequency distributions of stars measured "at rest". Comparing observed values of stars at different angles relative to the ship would give both speed and direction of the ship (peak blue-shift is where you're heading).. By incorporating relativity into the calculation this should work for speeds close to light speed as well. Inside a planetary system your speed is normally slow enough that measuring the position of the stars and planets should work. In space combat, absolute speed doesn't matter, only relative speed and especially acceleration. For that, gyroscopes and lasers should work. [Answer] The star ship is (presumably) moving from one point to another point. This means, the only relevant information is the distance from the departure point and / or the distance to the target location. Your speedometer gives you a speed as measured in distance per time. Now, provided you can measure the distance to your target, you can compare two measurements and get the delta distance in the time between the measurements. This is your speed. Now all you need is a display where this number is shown. [Answer] For useful navigation, we want to know several velocity vectors Assuming real-world physics and you're actually using orbital trajectories rather than 'warp-to-target' navigation: 1. Velocity vector to current position of target. This is highly relevant when you're already close to the target and trying to match velocities for a rendezvous maneuver. It's much less relevant for long-range interception, since the target is also moving along some orbital path and thus constantly driving 'toward' the object is not the most efficient way to arrive at the object. 2. Your orbital velocity vector relative to the dominating gravitational well in which you are moving. This allows you to predict your orbit with pretty good accuracy, presuming no encounters with other massive bodies along the way. Note that orbits include hyberbolic trajectories, such as escape from a planet's orbit. 3. Your velocity vector relative to the surface of a body you're orbiting. This takes into account the rotation of the body about its own axis and is quite relevant for things like landing or, say, plotting the path of your orbital bombardment laser across the surface. How would these vectors be measured? 1. Receive information about our motion relative to an observer, such as Earth. This would be the most likely mode of operation in a typical space-faring society, as we would have a network of observation points and communication relays constantly tracking all objects in the system. 2. For navigation in isolation, one possibility is using transmissions from [known Pulsars](https://en.wikipedia.org/wiki/X-ray_pulsar-based_navigation) to compute position. 3. Another possibility is to find something else moving along a known orbit and watch it move. This requires us to either be fairly close to the object or to have really good sensors. A motivating example for how these velocity vectors would be used To give a sense for how this would work in practice, it's helpful to consider the [Hohmann transfer orbit](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit), which is an efficient way to intercept another object traveling in the same plane in orbit around the same body. This is the kind of maneuver you would use to transfer from one planet to another, for instance. The time to actually perform the intercept is not just determined by the distance between the targets (which changes as they move in their orbits), but depends on several things: 1. It takes time to achieve the correct orbital phase for the transfer. This is a 'waiting time' before you even start the maneuver. At this phase we care about our orbital velocities (and hence our orbits), as these determine the correct point to perform the transfer. 2. It takes time to actually get near to the object. This is the actual transfer orbit duration and is the closest analogy to 'travel velocity'. 3. Once you get close to your object, you can match velocity. This is where the velocity to target finally becomes useful. Once you've mostly matched velocities, you likely also follow up with a maneuver directly 'toward' the object. At this point, the distances and relative velocities are very small compared to orbital trajectories, so gravity is mostly negligible and we can pretend things are more like the intuitive picture of things floating freely in space. Fair disclaimer, everything I know about orbital mechanics I learned by playing Kerbal Space Program. [Obligatory xkcd](https://xkcd.com/1356/). [Answer] Lets assume you are travelling at an appreciable fraction of C. Chances are you have some sort of shielding so the front of your ship (and then the front of you) doesn't get abraded away by the interstellar medium. Could you figure out some sort of measurement device that uses the activity of that shield? Could you then combine that with a known density of the interstellar medium? [Answer] It's very simple: you just need an accurate [accelerometer](https://en.wikipedia.org/wiki/Accelerometer). This is known as an [inertial navigation system](https://en.wikipedia.org/wiki/Inertial_navigation_system). Acceleration is measurable without external reference points. Just make sure to measure your starting speed $v\_0$ accurately when you're still navigating out of the solar system, before you turn on the warp drive. From then, you just look at the accelerometer, and compute your new speed from the measured acceleration: for every second of acceleration at $a\;ms^{-2}$, you add $a$ to $v\_0$. If you're accelerating in complicated ways, you'll need one accelerometer per axis. If you get close to a planet you'll need to correct for the planet's gravity, but then you have an external reference, so you can recalibrate. [Answer] If you're a sufficiently advanced race then placing a series of 'beacons' that pulse with known combinations of frequencies might be advantageous. The beacons would have to be very close together (in interstellar terms), due to the limitations of our signal broadcasting technology (We aren't as powerful as the stars yet), but this system could be used to string together known highways through space with the beacons acting as both 'mile' markers and GPS satellites. The relative power of various beacon's signals can be used to compute location in space, and if you couple this approach with Cyrus' answer on redshift you also get speed with a bit more accuracy. 'Speed' then becomes a value relative to this network of beacons. Obviously this approach doesn't work in a stellar system unless you have an unlimited amount of delta-V with which to hold the beacons in place, but if you're in-system you can use signals pumped from known celestial bodies (like Earth) to calculate speed. Any network in interstellar space will have to shift occasionally based on the relative motion of the stars, but any system using the stars as a reference for interstellar travel will have to compensate for that anyway. Oh, and it will be expensive to build and maintain, but depending upon your tech level and need for solid navigational information it might be worth it. One more upside: When you've got at least 66 different beacon-pathways, you get to build some awesome space diners. [Answer] > > 1.How would interstellar spaceship without FTL or wrap capability measures instantaneous speed accurately? > > > Other answers implied but no one blatantly stated the answer: you CANNOT measure an absolute velocity, which becomes especially obvious when in outer space. As far as we can tell, there is no such thing. Even on Earth, your "instantaneous speed" is actually relative to... the surface of the Earth! (Note that by definition, "speed" is independent of direction, and for a ship moving in 3-dimensions, the directional vector of its velocity is vital. Shades of Wrath of Khan!) Unless the exact timing is important, such as plotting out an intricate "battlefield" or going (fairly slowly) between planets inside a stellar system, you can usually assume that your planets aren't moving. Only the relative speed between the stars might be of any interest at all, and rarely that would be either. Relative position in 3-d space might be of interest, since there could be a considerable Z-axis distance between 2 stars that have similar X & Y coordinates. You didn't ask, but fortunately, several good suggestions about how to measure relative velocity were suggested. In practice, you would probably use a combination of things to describe your velocity, depending on your technology, location, and relative velocity; (continued in explanation for #2). > > 2.If instantaneous speed is useless for space travel then what kind of measurement would be adopted instead? (e.g. light year is used instead > of miles or kilometer etc.) > > > That will depend on how "fast" you are going relative to other bodies in space (that you care about), i.e. your "delta v(elocity)". Some examples could be: * small velocities/small scale objects - meters/second up to km/h -- typically for small boats, space-walkers and small to mid-sized ships approaching airlocks, space stations or other ships, missiles * inside stellar system cruising - likely in km/h up to km/s, which could get very large depending on your thrust technology and travel time. You would choose between /h or /s depending on how long it is traveling or how big a number you want to make it look. For example, the New Horizon probe to Pluto (fastest ship to date) left Earth at 58,000 kph, which is about 16 km/s. * interstellar cruising - could be the same as inside the stellar system, but probably will want it to be expressed in km/s because you're going to want to go way faster than even New Horizons. Hopefully you have some kind of continuous acceleration, and in that case, you'll be moving (relative from your departure place) a lot faster than even New Horizons. * lightyears - without an advanced, non-Newtonian (i.e. "impossible") space drive, you will never need to measure velocity in light-years unless you're trying to be cute. e.g. "lightyears/century" * Red/blue-shift or C - Mid-way through your decades/centuries long trips, you may find it convenient to use the red/blue-shift percentage of a set of "stellar beacons" or even your destination star, since your relative velocity could be a significant fraction of light speed... if you have a significant amount of acceleration the whole time. Or just use fractions or percentage of C (light speed) to simplify and make it more understandable to most people. E.g. 93% C or 0.93 C * Distances could run the gamete from meters to kms to thousands or millions of kms to light-years (remember that light-year has nothing to do with measuring time, it's just the distance unit of how far light travels in one year, the same as a meter is how far light travels in a fraction of a millisecond) * You would certainly want to measure distance between stars in light-years. It used to be common to use parsecs, but that's very Sol-centric. * Acceleration - likely in meters per second squared for known technologies, or as is commonly expressed, maybe in "gravities" where 1 G = 9.8 m/s/s - the acceleration due to gravity at sea level on the equator on Earth. This would only be needed if your ships could accelerate very quickly though. Unprotected humans can only stand a few G's, maybe as much as 6 G's without injury. [Answer] Special Relativity states that the relativistic mass of a object changes depending on your speed. If you were to measure the relativistic mass of an object on your ship you could calculate your velocity. [Answer] This answer assumes that Newton's laws of motion are in effect: In order to accelerate a vessel to some speed, including speeds greater than the speed of light, energy will be required to accelerate the vessel. If the approximate mass of the vessel is known, and the energy consumption of your propulsion system is known, and your efficiency is known, you can determine your acceleration, and thus current speed. Modern car engine control systems can monitor the amount of fuel that goes into the engine, and we can determine approximate fuel efficiency with certain basic tests. Based on this, in certain vehicles, we can determine acceleration, and thus speed based on fuel consumption. This has no basis in relativistic physics, and is based mostly in newtonian physics. This probably is a good thing, since if we assume we can break the speed of light by reasonable means, relativistic physics are questionable. ]
[Question] [ Spoiler: Wall of text incoming, TL;DR provided. Once upon a time there were two worlds, separated by some kind of dimensional veil. One world is populated by WW2 level industrial civilization, the other is a fantasy world, inhabited by powerful wizards. At some point the Veil dissipated, and the two worlds merged into one. These two civilizations waged war on each other almost immediately. The fantasy civilization is a feudal theocracy, ruled by the most powerful mages. When it comes to warfare, fantasy-landers almost always resort to illusion and mind control magic. When mages fight, they try to "hack" the enemy's brain in order to control or kill them. Simultaneously, they weave protective spells in order to prevent mind possession. There is also a type of stealth wizards as well, who specialize in illusion spells, that work like a [perception filter](https://tvtropes.org/pmwiki/pmwiki.php/Main/PerceptionFilter). All mages can be roughly divided into three levels, according to their power. * Level 3 mages are the weakest and usually don't get involved in wars, being employed as farmers, artisans and etc. * Level 2 mages form the backbone of magic armies. In terms of power, they pose as much threat as infantry with rifles, capable of casting various spells within ~500 meters radius. However, they can only "hack" visual targets (in other words, one can just hide from them behind some cover). * Every Level 1 wizard is basically an one-person army. These mages boast a huge ~10-20 km spellcasting radius, as well as having the ability to perceive the world in a "magic spectrum" - which means, anyone who isn't a powerful sorcerer or a Blank\* (see below) can't hide or defend themselves from such wizards, as no physical barriers can protect you from their spells. If they must, they can also cast powerful AoE elemental curses that destroy everything in a wide range area. Naturally, these wizards are rarest and make up ~1-2 percent of fantasy-landers' armies. Most powerful mages are also capable of teleporting themselves (and only themselves, they can't carry much cargo with them or transport others in such fashion) within the abovementioned ~10-20 km range. All magic combatants are taught how to communicate remotely with each through magical means. However, it takes at least five years to train a Level-2 wizard, while even talented apprentices have to spend decades to become Level-1 wizards. This means that fantasy-landers can't field a large army by modern standards. Though wizards are outnumbered by muggles (~10 to 1), the latters have no means of magical protection. In other words, even an apprentice mage can hack muggle's mind momentarily in order, for example, to turn the possessed soldiers against their comrades. Plus, many mages have an ability to feel when they're being watched, irregardless of distance. That means, trying to use snipers against enemy's officers would only result in alerting the entire camp, before a sniper makes a shot. Thanks to this, battlemages can also tell where the enemy is aiming - the sorcerers use this ability to dodge the incoming fire. So far I have come up with a few tactics that muggles might use against mages. * Trying to take enemy combatants out with artillery/aviation from afar AKA "[More Dakka](https://tvtropes.org/pmwiki/pmwiki.php/Main/MoreDakka)" While it probably wouldn't be that effective against Level-1 mages, muggles could just bring lots of big guns to the battlefield and suppress the enemy with superior firepower. Even telepathy can't help you to dodge a massive rain of bullets, missiles and shells. * Recruiting and deploying the so called Blanks. Among the muggles there is a rare genetic condition, which, besides other symptoms, grants the subjects a complete immunity to magic. Blanks are impervious to mind-control, can see through any illusions, and can't be detected through magic vision. Though, one can still hurt them with magic indirectly (for example, throwing objects at them with telekinesis and etc.). In particular, mages can't register their presence in aura or feel their gaze, so Blanks would make excellent snipers when it comes to fighting wizards. Plus, they would make a perfect counter against stealth illusionists. However, this condition is incredibly rare, which means that finding and recruiting Blanks would be an issue. * Getting the collaborating mages to teach the soldiers how to defend against hostile spells. Some mages will desert to the muggles eventually for various reasons - and offer their skills and knowledge. Though one can't become a proper battlemage in a short period of time, even novices can weave some protective incantations, that might buy you some time, before a mind spell gets you. In a nutshell, such protection serves as a magic equivalent of bulletproof vest. Though it still won't save soldiers from the most powerful mages. So far I have come up only with a few ideas on how muggle officers would respond to such scenario. In short: *TL;DR: What can WW2 army do against HarryPotter-esque wizards who are willing to cast Imperius at every opportunity?* P.S. Neither of the warring parties possess nukes or their equivalents. P.P.S. Because of strict religious taboos, the wizards aren't going to use any of muggle tech. Edit: Concerning Level 2 mages. The spellweaving process involves inputting a sophisticated coordinate system, i.e. "telling" a spell where it should strike. When a mage sees the target (even if they wear a thick armor and an impenetrable gasmask), it is much easier to send a spell at the right coordinates. It is still possible to try and attack someone behind a wall or inside a vehicle, but in that case the risk of failure is way higher. Edit 2: Concerning the mind control magic mechanics. When a mage weaves a mind control spell, they send a special signal to a target, containing a specific order. If the target fails to resist the spell, they obey the order without any questions. However, if the victim was cursed by a relatively inexperienced mage, there is a chance that the hypnotized person might break free from the spell, if they have strong willpower. Alternatively, a wizard can maintain persistent connection to the target, thus turning the victim into their willess puppet who does anything its master wants. As for the limits of this ability, it all comes down to the individual wizard's mastery over magic. The most powerful mages can singlehandedly enslave entire platoons for many hours, while your average infantry level sorcerers can control at best a few soldiers for less than a minute. Those, who are exceptionally skilled at MC magic, are capable of influencing the others minds imperceptibly - picture the Indoctrination from Mass Effect. Their victims, while remaining fully aware, can't help but obey the orders they were given. However, such mages can be literally counted on the fingers of one hand. As for detecting the signs of mind control by magical means (once the muggles have turncoats) - again it all boils down to who cursed a person with a MC spell. If it was a highly professional wizard at work, it's unlikely that, say, a L2 turncoat mage could tell if something's wrong. [Answer] # Death from Above You can mind control all you want, but if you can't see them, you can't magic them. To see them, you need to be at level with the crews... but the humans are fielding planes that could routinely fly beyond 40,000 feet, some fighters inched in on 50,000 feet. That's the area of 2.7 to 1.6 PSI - or in other words "not breathable, ice cold and deadly", and so impossible for broom-based air defense. Even Mount Everest sports at least 4.8 PSI and you need oxygen to get up there. The ceiling for anyone flying without Oxygen is only about 15,000 feet, and [at or above 18,000 feet (FL180) pilots generally want to have oxygen masks](https://www.planeandpilotmag.com/article/flying-high-unpressurized/) as nasal extra oxygen just doesn't cut it at that height. So we can say assuredly, that the muggle Airforce has uncontested high air superiority. And that is all they need. The moment the high air is free, the death comes in the shape of [strategic bombing.](https://en.wikipedia.org/wiki/Strategic_bombing_during_World_War_II) Cities of the wizards turn into burning hellscapes, their castles are turned rubble and fleets of [B-29 Superfortress](https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress) strafe the airspace at somewhere between 30,000 and 31,850 feet, unable to be made out from the ground, dropping carpets upon carpets of incendiary, high explosive bombs, devastating everything below and making trying to detonate them in the air highly problematic for the mages. These planes fly so high, that even if they could be reached by the high-level mages, the mage would need to be pretty much right below them and then would need to know that it is there - at which point the bomb load destined for that mage's position already is on the way downward. That bomb carpet has been dropped about 170 seconds before the plane passes the poor mage and was dropped when the plane was about 25 kilometers or 16.5 miles away. Oh, and the plane isn't watching for the wizard by themselves, they are only a spec on the scope anyway. The plane's crew is watching only for the street or town, or even just coordinates and dropping on schedule. # Who needs to aim?! It's time for [Hailstorms](https://en.wikipedia.org/wiki/BM-21_Grad) made by men! While the air campaigns ravage the countryside deep within the magical kingdom, Trucks only need to get close to where the muggles draw a line for their approach. About four kilometers to be frank. These trucks are properly named after a [Russian song](https://youtu.be/7J__ZdvsZaE?list=TLPQMDYwNTIwMjKmfLhRB87iNA) and their BM-13, BM-8, and BM-31 will start to sing a howling song of large area devastation and death on the borderlands, then they retreat and reload as the next battalion draws in some hundred meters to a different position and unleashes its barrage anew. Yes, the [Katyusha, also known as Stalin Organ](https://en.wikipedia.org/wiki/Katyusha_rocket_launcher) with its area denial-and-destruction will eradicate any border guard and battlefield on so much distance that the wizards can't make out the vehicles as being there at all. Because they don't generally look for the target but just need to roughly aim in the right direction, the wizards have little to no forewarning as streaks of flame come diving in on a low trajectory, plowing under the landscape and blowing up everything. And with the united human production might behind it, that hailstorm could be kept up 24/7. # Death from Afar But we can deliver more devastation from further afar. Let's grab the German arsenal of the [Aggregat 4](https://en.wikipedia.org/wiki/V-2_rocket) design, which delivers 1 ton of explosives over 320 kilometers (200 miles). It flies beyond the height that it can be intercepted at all (about 88 kilometers at the long-range shot). The moment it enters into the range of a class 1 caster, that caster has about 12.5 seconds to not only detect the missile (which doesn't see the wizard) but also decide on the spell, aim and cast it. In other words: Defense is meaningless, especially as the rockets are only rudimentary aimed and hit within a very large area. However, unlike Germany in WW2 (which relied on reports from spies where they had hit), the united muggle front has Superfortresses and aerial reconnaissance planes that can work as spotting aircraft and give the impact reports on the long-range missile strikes - even without seeing the wizards as they use aerial photography and filming. # Welcome to No-Wizard's-Land Humans have learned how to build modern fortifications in the Great War. Muggles learned how to do that in pretty much no time using concrete and rebar. Only days after the magic kingdom is discovered, the first bunkers are built at the border. Behind them, a series of permanent artillery emplacements are erected. The moment hostilities begin, artillery strikes deep into the Wizard Kingdom start, destroying villages close to the border when heavy shells hit [up to 22 kilometers](https://armyhistory.org/u-s-and-german-field-artillery-in-world-war-ii-a-comparison) away from the border garrison. Without seeing the actual target, these artillery pieces fire in a high arc. The spotters that tell where the shot lands are in balloons and planes, often not even entering the enemy-controlled zone as they only need to direct the fall of the shot roughly - artillery is an area denial after all. As the artillery and smaller pieces fire, the first 20 kilometers of the Wizard Country are literally plowed under and turned into a moonscape in which movement becomes very apparent. [Forests turn beanstalks, fields turn mud craters, houses turn ruins.](https://en.wikipedia.org/wiki/No_man%27s_land) To combat the approach of invisible wizards, not just normal loads are flung at the enemy, but short incursions into enemy lands are taken by engineers to deposit thousands of anti-person mines, barbed wire, electric fences, wire-controlled charges, and automatic, tripwire-activated machine guns into the no-Wizard's-Land. All of these act as a strong deterrence for wizards to approach the border, turning those that try into chunks, metal spiked corpses or electrically dried/fried mummies before they can get into effective combat range. The message is clear: approaching beyond the line drawn by artillery is death. # Even the Air wants to kill you If the wizards don't surrender because they are literally bombed into submission and have their lands set ablaze by hailstorms of small missiles as well as large cruise missiles blasting every strategic, tactical and governmental target there is into smithereens, then it is time to unleash the banes of the War to end all Wars once more: [CHEMISTRY.](https://www.un.org/disarmament/wmd/chemical/) Once the muggles unleash the nightmare of chemical warfare on a couple of large cities that haven't been turned into burned hellscapes in the indiscriminate bombings already, the wizards will be faced by the victims of Phosgene, Chlorine, SARIN, LOST, and all the others. People are choked to death by something so intangible, that the wizards have no idea what hit them, and they are too proud to use the one thing that would help: Gas masks. The delivery is even too simple to understand by them: there come barrels and nothing more. Only as they hit the ground they burst open - and unleash their deadly cargo. In the No-Wizard's-Land at the border, artillery delivers canisters into the zone, turning the puddles of water into acid, possibly even detonating seemingly at will to release deadly clouds while on some days barrels with the agents are opened at the border to have wind carry the gases over the border. It might not be the most efficient way of delivery, but Chlorine is a chemical waste and available in hundreds of tons. Besides choking agents, other loads might deliberately contain toxins that poison the water or defoliate trees and turn the whole magic kingdom into a barren wasteland after a few weeks of bombardment of the fields and rivers. Rainbow Herbicides might be chosen deliberately for their ability to destroy not just the foliage but their lasting damage to the ecosystem. Once the united human war machine is done with the country, there will be nobody left to try and stand up against them. # Hunter-Killer Groups How do the Blanks and Turncoats enter the picture? At best, the blanks are drafted into special Hunter-Killer groups, armed with small guns and explosives. These infiltrate the enemy lands in safe zones. Safe from the muggle front's bombardment for the time that is. These agents disguise themselves as ordinary people of the country, seek out high level mages and due to the nature of being blanks and then assassinate those leaders either by popping a bullet into their head or blowing up the house they sleep in. The Turncoats will not need to teach to defend against attack magic, no, they are used to create the most deadly soldiers by using the very tactic of the evil mages: by using specially tailored mind-control spells. The command is simple and effectively delays the next attempt to mind control them with its phrasing: When you are ordered to kill a comrade, kill the caster of that spell first. # Conclusion If the wizards don't surrender, they will be thoroughly wiped from the face of the earth by the combined military-industrial complex of the USA, Germany, and the USSR. Fighting the Wizards is not a fight to win territory, it is an absolute total war for the survival of humankind! There are no silk gloves when dealing with mind-control wizards, rules and customs of war don't apply against something where defeat means the annihilation of humankind. In the war against an aggressive overlord wanting to subjugate any and all human, no punches are pulled. Common enemies unite. [Answer] /When it comes to warfare, fantasy-landers almost always resort to illusion and mind control magic/ Destroy their infrastructure. This is how modern muggles make war. Your fantasy folks will not be used to that. You can't mind control a dam or a bridge or a dike. Illusions will not put out fires. Even if you got magic up the wazoo you still have got to eat. Your muggles attack the infrastructure of magic land. They use planes and rockets and saboteurs. Cities burn. Fields flood. Granaries are spoiled. Bridges fall. If your magic folks are at a pretechnological level it will be hard for them to counter this. If they have their megawizards ready to mind control opposing soldiers on the battlefield, those wizards will not be psychically watching for planes dropping incendiary bombs on their capitol and V2 rockets blowing up their dams. It is not a very elegant way to make war, burning medieval cities from the air. It violates the rule of cool in a couple of ways. But it is effective and was very much done in WW2. The idea is to have the wizards decide to make peace before everything they have is ruined and their people starve. [Answer] # Same as every other first contact: smallpox. Your muggles have had their vaccinations. The wizards don't understand vaccinations. Your muggles mass produce smallpox and rain it down in smallpox balloons all over the wizards' territory. Sometimes they even leave blankets with cheerful patterns woven in, as a gesture of friendship. When some wizards survive that, the muggles break out the monkeypox and the camelpox ... there are actually a fair number of pox viruses to work on evolving and making vaccines for, and very few other practical uses for wizard POWs who make you kill your friends and yourself if they ever manage to get their gags off. Don't forget the polio and the yellow fever... there's a lot of science to do. Lots of comments on this one! I didn't think about the order of desirability for attacks here at first, but I think it might be... 1. Anything the muggles have already been vaccinated for (smallpox), or consider themselves to "universally" have been exposed to (mumps, measles). 2. Anything the muggles have a vaccine they could give out to more and more people at the conflict zone (yellow fever) 3. Anything the muggles think is virtually inevitable to be exposed to (malaria if the contact is in an endemic region) 4. Anything the muggles can rapidly research a vaccine for, given the desire to, based on existing data (actually, I should correct myself here - while it's not known, most likely monkeypox is a threat to humans because the smallpox vaccinations are too old to be protective, not because of a lack of cross-reactivity) 5. Preferably not anything like bubonic plague that requires treatment for those exposed, since the wizards can make them infect each other, then cut off their access to supplies. (But in a pinch, whatever works) Chemical weapons are right out - they'll get sprayed around inside the forward base, and be far more deadly to the muggles than the wizards. Oh, yes, and if the wizards do get past their prohibitions and adopt muggle vaccination tech, then you're pretty much out of luck with this. If they can control minds, they might read them; in any case they can make the experts explain everything about how to do the vaccination, and recruit teams to go in and steal the vaccines for them. [Answer] More tactical rather than strategic suggestions, but here we go: ## Two-man Teams It might be clunky and dumb, but one way to avoid soldiers turning their guns on each other, might be to make it so that no one man controls the weapons. So one soldier carries a gun with no trigger. Another soldier, preferably always out of sight of the mages, carries the trigger, connected either via radio or with an actual wire running from trigger to the gun. ## Drones WWII also had early drones like the German [Goliath Tank](https://en.wikipedia.org/wiki/Goliath_tracked_mine) or Russian [Teletanks](https://en.wikipedia.org/wiki/Teletank). While these generally require an operator to use his or her own eyeballs, it would be able to put the actual mind-controllable soldiers further from the mages. These might be combined with the Two-man Team, so that the guy watching the battlefield isn't actually able to use the weaponry him/herself. ## Blockers So Level 2 mages can only hack "visual" targets. What counts as visual? What if I'm looking at you through a mirror/periscope? What if I'm behind a one-way mirror / tinted glass? Periscopes could work for rifles firing out of cover without exposing the soldier. One-way / tinted glass could be installed in tanks or other fighting vehicles. If periscopes don't work, it might also be possible to install cameras on you vehicles, and control them via a screen inside. Or use this in combination with a drone (though it might require a wired connection). Vehicles with cameras probably isn't going to be a mass-produced technique at this tech level, but I could see some attempts being made. [Answer] > > Plus, many mages have an ability to feel when they're being watched, irregardless of distance. That means, trying to use snipers against enemy's officers would only result in alerting the entire camp, before a sniper makes a shot. Thanks to this, battlemages can also tell where the enemy is aiming - the sorcerers use this ability to dodge the incoming fire. > > > What's the limitations of this? Is it just a general sense that "we are being watched"? Or do they know who is watching them and where? Does this still work if the perception is indirect, or example, via a video camera? Depending on how things work, there could be many ways around this: 1. Indirect observation, for example, if it doesn't trigger perception. WWII had for example the Vampir infrared scope and primitive CCTV. Perhaps we can even insert a delay on the CCTV - does it still count as being watched, if there's a 1 second delay? <https://en.wikipedia.org/wiki/Closed-circuit_television#History> <https://en.wikipedia.org/wiki/Zielger%C3%A4t_1229> 2. If these are detected, then we can flip the idea around - we can try to jam the high level wizard's sense by having them be "watched" all the time. For example, lots and lots of cameras all over the place, with wide-focal lens that technically are watching a huge area. Get the wizards complacent and used to the uselessness of their sense. And then boom. [Answer] As said in other answers, the hard-counter to your mind-control spells are investing air warfare and doing carpet bombing. To a lesser extent, heavy artillery strikes are a good alternative, though it's less mobile. However, let's further extend the concept and involve all of the militaries forces, especially in the early parts of the conflict where the forces haven't redirected most efforts into air yet. ## Only YOU can smoke'em [![Smokey the bear](https://i.stack.imgur.com/eeOIH.png)](https://i.stack.imgur.com/eeOIH.png) [Smoke will prevent 9 out of 10 mind-controls!](https://commons.wikimedia.org/wiki/File:Smokeybear1944.jpg). [From Wikimedia commons](https://commons.wikimedia.org/wiki/File:Uncle_Sam_style_Smokey_Bear_Only_You.jpg) Smoke is a great tool to prevent clear visuals on a target. What makes mind-control so difficult to counter? It's not the effect of the magic, it's that it's triggered by mere visibility. Now send smoke grenades and shells everywhere the enemy troops are, and protect your troops the same way. You don't have to worry much about your troops not seeing much. Indeed, while the wizards won't make a single hit, your guys still have bullets that can kill and don't need accurate sight, so your damage potential is much higher than them than if you lacked smoke. Before, just use small mirrors behind cover to check where you have to shoot, roughly. And of course, for better chances of hitting something you want SMGs and machine guns instead of bolt-action rifles. And don't forget gas masks, too : the [M18 grenade for instance release fumes](https://en.wikipedia.org/wiki/M18_smoke_grenade) which are toxic if you breathe them all day, 7/7, all-year long. The more the war progresses, the more tools can be developped against this threat. A very simple one to set is to put a smoking device on every gun, triggered on the first shot. It ensures nobody forget to cover when attacking, but it also makes the wizards losing the mind-controlled ones from sight when they lead coat their friends, reducing friendly casualties potential. ## Avoid engagement until nights Again, visibility is key. Night reduces visibility, so prepare your biggest assaults during nights. Your guys don't see well, so they won't trigger the wizard's instinct as easily. Besides, it increases the size of any unlit covers, since it's much easier to confuse what is a rock with someone's back. To further enhances any heavy assaults, use strong spotlights to blind the enemies. You'll see them, but they cannot see you, therefore they cannot target you. It's even better than smokes, in some ways. ## A (non-)peak into vehicles Vehicles are key for this warfare, and I mean not only tanks. As soon as the inner working of illusions is known, replace the windows of every trucks, jeeps or basically any vehicle to use one-way mirrors -invented in the 1900s, or tinted glass (or... Smoked glass! I like smoke). A probably cheaper approach would be to use blinds instead; Simple, sturdier and still prevents line-of-sight with the drivers and passengers. In case a driver happens to be mind-controlled (broken window, for instance), it's easier to get rid of them than them to get rid of you. It's because vehicles supported by a whole infantry unit is a common allied formation, while a surrounded vehicle by enemies is a dead vehicle. Moreover, moving around is very limited, both by roads but also any obstacles your vehicles will quickly pass by, cutting the line of sight. ## Handling rebel mages As soon as you get your first rebel or mercenary mages, use them at the door step of every recruitment center to detect blanks. If one recruit cannot be mind-controlled, it's a blank and must be treated more carefully. Otherwise, yes, develop mindproof protections to reduce the likelyhood of someone being turncoated if they're not being careful. Using them on the frontline is a waste of resources (ratio of 1 to 1 kill, but you have much less rebels, so...). However, be sure to put those mages outside of any leading parties, it's very dangerous to have someone you don't have high-trust in with mind-control abilities near a general, for instance1. Ideally, you want to have blanks in leading positions to reduce risks as much as possible, and use extensively radios and sight-protection methods otherwise. It's not ideal, but it'll have to do. --- --- 1 : [See Yuri in Red Alert 2, it doesn't end well for the Allied forces.](https://www.youtube.com/watch?v=fnd0qg4I_MM) [Answer] The best ideas (strategic bombing, chemical and biological weapons, mirrors, vehicles) are already taken, so here are some weaker ones. ## Naval warfare Battleships were effective at 20 miles, carriers at 200. That ought to be enough to make life difficult for Hermione and co. The muggles will have uncontested submarine supremacy which should prevent any attempts to mind control a ship. ## Landmines Can wizards detect landmines? If not, then mine the hell out of everything. Use poison mines if possible. ## Blank torturers Blank Gestapo or NKVD agents, or Allied or Japanese torturers will be useful. Once you have a few blanks, you don't just have turncoats available to find more blanks, you have tortured wizards. With a little thought, you can come up with creative ways to get captured wizards to help filter for blanks. Captured Level 1s, while immensely dangerous, could be quite useful. This strategy allows turncoats to be used on the front lines more. ## Tank charges WW2's main tactic may still be quite effective versus wizards, particularly in open countryside where a single mind controlled or broken tank won't hinder a column. This will depend a lot on how well armor stacks up against level 1's AoE attacks. ## Microphones Wizards may be able to tell when they're being watched, but can they tell if a mike is picking up their sound and amplifying it into headphones (or a radar style map) inside a bunker or urban building? As soon as the distance gets close enough, pop out and use shotguns or grenades or a machine gun or some other indiscriminate weapon. ## Propaganda, bribery, ideology and religion With 10 times the population (?) and an industrial economy, the muggles can offer turncoats lifestyles that the wizards cannot and will not match with a feudal society, and have the media power to let the wizards know it. The wizards will be appealing to many, but most people will realise that being a muggle in a magical world, and banned from using technology, is serfdom. Not only that, but the muggles will be centuries ahead in ideological development. Between liberal democracy, fascism, Nazism, and socialism, there will be something that the magic peasants go for. Every side in WW2 became masterful at propaganda. And that's before the wizards encounter Christianity and the other major religions. What happens when a level 1 reads about an untrained carpenter who can still storms with a word and rise from the dead, while laying down some great morals? Even an 0.1% conversion rate is going to have BIG consequences. Furthermore, as soon as a few percent of the mages start to use technology, the wizards are going to have the mother of all religious schisms on their hands. ## Drugs and alcohol Have the wizards gotten used to drugs and alcohol? If not, they're in for a lot of social dysfunction. ## Guided rockets Mass produced V2's could really change things. I guess V1s would be just as ineffective as they were in real life. ## Political commissars or MPs Some sort of troops dedicated to killing or incapacitating mind hacked troops will be necessary. They should be positioned to have good line of sight of their own troops but none of the enemy's. ## Mass blanks Blanks don't have to be of military age to be useful. Even a 5 year old blank can detect illusions. With a population of 2 billion, a blank rate of 1 in 10 000, and 70% blank usability, that's 140 000 blanks. At 1 in 1000, there's 1.4 million blanks. [Answer] # Aluminum Foil Hats [![Aluminum Foil Hat](https://i.stack.imgur.com/J1ElB.png)](https://i.stack.imgur.com/J1ElB.png) If they stop the government from reading your mind, they should stop mind control spells too :P For a serious explanation, if magic exists in the electromagnetic spectrum, then a faraday cage around the head would stop mind control quite nicely. It could even be incorporated as a liner in standard army helmets. As a fun add-on effect, [chaff](https://en.m.wikipedia.org/wiki/Chaff_(countermeasure)) would work to stop other battlefield spells much like it did in actual WWII. While aluminum foil seems like a silver bullet (pun intended), it's limited in power because the muggles would soon run into the same problem faced by the Allies in WWII: aluminum foil shortages (as is wont to happen when you dump tons of the stuff on your enemy during every bombing run). At that point, the war becomes what war actually is: a battle of logistics and economic power. ]
[Question] [ Let's picture a medieval world, where a tribe of Viking-like mercenaries live for the thick of the fight, the blood nourishing the ground, and the honour of the gods of war. So they are equipped, trained for skirmishes and wars. Their equipment would be Viking like, for instance: * Round shields along with short swords and spears, especially used for battle formations. * Axes, but probably more used as all-purpose tools than on the battlefield. * Longbows and possibly javelins for ranged options. * Thick leather and fur armor; less resistant than full-plate ones but still enough to prevent a cut or two and lighter to wear. Chainmails are also there to supplement the defense of the frontline. * Iron helmets (horns not included) * Some horses Now, a small part of this tribe goes much further in this battle mindset to an almost fanatical aspect of themselves. Being stronger, faster and more endurant than other soldiers and having access to the same equipment, they take enhancing drugs to be truly one with the battlefield and have a seat among their gods when they will expire. With that comes an increase in adrenaline, loss of fear, acutened senses, and much stronger pain resistance. Note that drinking the decoction is quick and the effects start to take in fast too, like 1 to 2 minutes at most, making one ready against even surprise strikes. Depending on the quantity taken, the drug can last from 1 to at most 4 hours. taking for longer than that is dangerous to the health and have nasty adverse effects. The big downside is that they lose control of themselves : Apart from other berserkir, They barely recognize friends from foes and, due to their excitement, they have a difficult time refraining their pulses to charge the enemy, unable to follow a sound formation. Your perfect berserker, in short. ## Now that the setting's set, what tactical advantages can be taken from such units, in a battlefield? For the purpose of this question, we will assume that the enemies have approximately access to the same kind of equipment and troops (minus berserkir). Also, until they become frenzied, berserkir can and will follow orders. However, they refuse fight orders if they are not frenzied : If you send them on a charge, they will take their drugs beforehand. Having thought a little ahead, sending them with other units looks like a real bad idea for obvious reasons, but sending them alone on the frontline isn't any better. Indeed, battle formations are exceptionally strong against a disordered charge, as the attackers literally impale themselves against the enemy line. I can picture quick skirmishes and guerillas on the logistic lines would work quite well, but during a direct confrontation, hmm... I have a hard time seeing how and where one should send them to get the most out of them. So what advantages can you get from them on the battlefield? This comes with many subsequent, related questions that may be interesting to look at to find an answer. For instance, when should they be deployed and where relatively to other troops? What would be their favored environments to fight in (forests, mountains...)? Would they have good match-ups against specific troops types? [Answer] pretty much a shock troop or human stampede, since cow/bull is expensive and cant row a ship, assuming this was in open battlefield or raid. it even state here from:<https://en.wikipedia.org/wiki/Berserker> > > King Harald Fairhair's use of berserkers as "shock troops" broadened > his sphere of influence.[citation needed] Other Scandinavian kings > used berserkers as part of their army of hirdmen and sometimes ranked > them as equivalent to a royal bodyguard.[24] It may be that some of > those warriors only adopted the organization or rituals of berserk > Männerbünde, or used the name as a deterrent or claim of their > ferocity. > > > * intimidation, most battle is won by making opponent surrender or running away, rather than total slaughter, there even some opponent that chickened out after seeing berserker bit their own shield like madmen. * they wont run away or chickened out, which is one of the element in losing battle. * distraction, the ruckus they make can help opponent attention focusing on them while making other troops unchecked or unnoticed, and if they get surrounded or stuck inside enemy formation they can help harassing the enemy to buy time or create an opening in opponent formation. * will keep moving or charging forward in attempt to hit the enemy, even when impaled, just like boar (thanks to adrenaline, and they are numb from pain), and the momentum can help breach or disturb the opponent formations (assuming opponent use shield wall formation) to give an opening, you can make your berserker as the frontline while the back row follow/push them behind to form boar snout or wedge formation as discarded warriors since the frontline is likely death from the impact anyway (make sure the berserker can only see forward or block their side view so they wont attack their fellow berserker beside them, for example use a [horse blinder](https://www.horsetackdatabase.com/wp-content/uploads/2020/03/sue-hughes-OzMleYUe5vQ-unsplash.jpg), and of course it have risk that they end up attacking your own men just like how handling animal to charge is, from elephant, to bull, to boar, wolf or dog, sometime even horse). > > Svinfylking – boar warriors > > > In Norse mythology, the wild boar was an animal sacred to the Vanir. > The powerful god Freyr owned the boar Gullinbursti and the goddess > Freyja owned Hildisvíni ("battle swine"), and these boars can be found > depicted on Swedish and Anglo-Saxon ceremonial items. The > boar-warriors fought at the lead of a battle formation known as > Svinfylking ("the boar's head") that was wedge-shaped, and two of > their champions formed the rani ("snout"). They have been described as > the masters of disguise, and of escape with an intimate knowledge of > the landscape.[6] Similar to the berserker and the ulfhednar, the > svinfylking boar-warriors used the strength of their animal, the boar, > as the foundation of their martial arts.[6][23] > > > here image of boar snout formation [![enter image description here](https://i.stack.imgur.com/Md1Gm.jpg)](https://i.stack.imgur.com/Md1Gm.jpg) regarding terrain or environment, definitely not in forest as a wise berserker say [![enter image description here](https://i.stack.imgur.com/2125o.jpg)](https://i.stack.imgur.com/2125o.jpg) in my opinion the best terrain for them is a chokepoint or narrow place, as the famous berserker that defend the stamford bridge has shown. from:<https://en.wikipedia.org/wiki/Battle_of_Stamford_Bridge> > > The sudden appearance of the English army caught the Norwegians by > surprise.[14] The English advance was then delayed by the need to pass > through the choke-point presented by the bridge itself. The > Anglo-Saxon Chronicle has it that a giant Norse axeman (possibly armed > with a Dane Axe) blocked the narrow crossing and single-handedly held > up the entire English army. The story is that this axeman cut down up > to 40 Englishmen and was defeated only when an English soldier floated > under the bridge in a half-barrel and thrust his spear through the > planks in the bridge, mortally wounding the axeman.[15] > > > This delay had allowed the bulk of the Norse army to form a shieldwall > to face the English attack. > > > because in chokepoint situation, opponent cant use their number (if they have superior number) and formation well, while berserker has advantage in individual prowess to mow them down as single army and you can send another small number of berserker to replace it, if the previous berserker is down, or tired, or the drug effect is over. the problem with berserker is likely they really lack defense or movement fighting style that protect themselves such as dodging, so range opponent may has chance against them if they lose their shield or the shield is to burdensome from the barrage of arrow/javelin stuck in, but it can be mitigated their survivability (at least until they reach opponent side) if the berserker wear the best armor for that period, such as chainmail for example. [Answer] Morale. In a typical pre-modern battlefield, most of the casualties are not suffered in face-to-face combat; rather, one side or the other will lose their nerve and rout, leading to them being run down by the enemy. Berserkers, however, won't break - they're too busy berserking to worry about trifling things like self-preservation. In an evenly-matched fight between a unit of berserkers and a unit of regulars, the berserkers are extremely likely to win, simply because they're willing to fight to the last man and most enemies aren't. The enemy will end up breaking first. [Answer] # Shatter the enemy morale > > Listen, and understand. That terminator is out there. It can’t be bargained with. It can’t be reasoned with. It doesn’t feel pity, or remorse, or fear. And it absolutely will not stop, ever, until you are dead. > > > -- Kyle Reese, The Terminator I can easily imagine the foes something something to that effect about the bersekir. They'd be fearsome and ruthless. It's going to be enough to shake and frighten the enemy combatants in many cases. Can you picture it? This...man, just hacks at your brethren and coming at you. Doesn't flinch when his own comrades are injured or killed. Doesn't seem to notice his own wounds. Just. Keeps. Coming. At you. Whatever their actual combat effectiveness, they can be undoubtedly scary. They can drive the enemies to turn and flee rather than face them. And a fleeing enemy is not a fighting enemy. ## Environments The berserkir can be fairly effective in most terrains. Perhaps decent visibility is the greatest boon. You want the enemy to see what the berserkir can do. A forest might give a slight advantage as it hinders archers and enemy mounted troops, as well as some formations. All things that benefit a berserkir. ## Troop matchup Unfortunately, while berserkir can be quite effective in scaring enemies, this advantage is quite easily negated. If you're not scared of them, there is not much advantage to sending them forward. A well disciplined army will ignore fear and march forward. This is how Rome prevailed in the early days. A Roman soldier would be conditioned to just keep fighting and following orders regardless of friendly casualties. This can effectively eliminate or at least vastly mitigate the scariness of enemy troops. Furthermore, a well coordinated army would easily take out a mindless killing machine. Surround, keep the shields up, and stab them. Another issue is just keeping the berserkir at bay. A spear can attack them without exposing the attacker to harm. Horse riders can incapacitate and kill berserkirs and seek them out on the battleground. Arrows can also be quite effective against them at open plains. [Answer] # DISTRACTION CARNIFEX! What is a DISTRACTION CARNIFEX (and yes, the term must be in all caps) you might ask? It's a big, durable, psychologically scary unit that draws a disproportionate amount of enemy attention to it due to it's perceived threat value, while the actual backbone of your army gets into position to get stuff done. The other importance factor of a DISTRACTION CARNIFEX is that they're relatively expendable. They might have dangerous weaponry, but they're never the heaviest hitting and it's not a lost battle if they die. A DISTRACTION CARNIFEX can be dangerous, but only if it's left alone and not focused on. They punish the enemy if they do not focus on the big, scary distraction. The way a DISTRACTION CARNIFEX works is as follows: 1. Your berserkers start screaming "*[BLOOD FOR THE BLOOD GOD](https://youtu.be/9-gSJW3sHXE?t=29)" and charge the enemy lines. 2. Your enemy is quite understandably startled by these lunatics rushing at them and starts opening fire with dakka 3. The berserkers tank some hits before they get stuck in the foes' front lines because they have armor, don't feel pain, and because "they are absolute lunatics" 4. In the time it takes for the enemy to deal with the problem, your ranged units have gotten themselves set up for maximum efficiency and the rest of your army has advanced across the field without being winded or pelted by ranged fire 5. Wait until the berserkers are mostly dead to avoid friendly fire. Or just bring an army of berserkers and mostly ranged units with the remaining melee units most existing to guard the ranged unit's flanks from cavalry and infantry like in a typical pike-and-shot army. 6. Profit Another advantage can be seen with the Saurus warriors in Total War: Warhammer. Saurus warriors are really tough, but have the tendency to go berserk in game when below 50% health. However, because they are front-line melee fighters, they tend to go berserk only after they are firmly stuck in the enemy lines, holding enemy troops in place for bombardment by ranged units* (that is, if their faction they belong to had any ranged options worth writing home about). In fact the berserking is actually a net positive because it means they won't lose morale and flee the battle when the tide turns against them, which means they will effectively lock whatever troops they are fighting in place and will usually fight to the last man. The Dwarfs in the same game do something similar but are just highly-disciplined (and actually do use the ranged advantage), rather than going berserk. By the way, and this is important, DO NOT put a berserker on horseback. Berserking completely negates all of the advantages of cavalry, which is the ability to maneuver and perform hit and run attacks. Not to mention at that point the horse is smarter than the berserker and might refuse to obey its rider or outright buck them off. You learn this in Total War: Warhammer after your Velociraptor cavalry leaves the battlefield chasing after an enemy scout because it got a paper cut. Berserkers are usually more of a liability than a tactical advantage. You can't get them to retreat if the battle is lost, you can't get them to reposition if a vulnerability opens up in enemy lines, they'll kill your soldiers if they come too close in the heat of battle, they're a potential discipline problem out of battle, and you can't give them good arms or armor because they're likely to be killed behind enemy lines and lose it. They're basically expendable cannon fodder, which is an issue because you need training in order to know how to use the berserking potion effectively (as well as have the physical fitness and muscle memory to make use of it). They trade tactical flexibility for being a really big hammer, and completely fail to present an effective plan B when "having a big hammer" isn't good enough. I'm reminded of something I read on Tv Tropes... > > Singers loved berserkers for their deeds, lords loved them because they didn't have to buy them armor or decent weapons, (and didn't have to pay them after they inevitably died) and no one else remembered them, because they seldom lasted longer than a raiding season or two. > > > -- Tv Tropes, paraphrasing a dialogue in the comic Northlanders [Answer] How about: * Useful for suicide missions if that's an option, as they won't surrender when bezerking, * Useful as a diversionary tactic when they're up against a superior force for the same reason. * Useful in depth strike (behind-enemy lines missions), where they infiltrate calmly, find a target, and then can attack the target with more force because of the bezerking effect. * possibly useful in close-quarters battle where they're confined: 'Send the berzerkir through the breach into the enemy keep!' and then use your own disciplined troops to guard the gap and keep them in there! But you couldn't do anything large-scale with them. On a battlefield, discipline and control are essential to integrate and coordinate your infantry, cavalry, artillery (archers), fortifications, and reserve in time and space. Having a unit that goes totally off-plan for a couple of hours is not going to help that coordination at all, and you'll lose to a similar force who can tactically withdraw, and take advantage elsewhere on the battlefield. [Answer] Propaganda Equip some of your less-able-to-fight troops with bagpipes. Whenever the berserkers are on the field the pipers play their most warlike tune. The enemy will get to know this tune and word will get around. The mere thought of berserkers coming their way will cause huge psychological damage to the foe and loss of morale. The tales are sure to be exaggerated. [Answer] WAIT UNTIL THE TIME IS RIGHT It sounds like you have pretty good control over them until they drink their potion. But you don't get any of the positive effects until they drink it. So, don't let them drink their potion until they are just about to engage in battle. Move them around tactically, use standard tactics and formations - have them behave just like any other troops. In fact, if they can't be distinguished, that's even better. Then, right before they make contact, give them the command to drink. As you said, you won't get an immediate effect, but I doubt they'd rout at that point, which is the usual reason you lose battles. The fear is that your enemy will bait them with a feint or a small force. For example, an opposing cavalry charge could run straight at them, then turn away. If they drank too soon, then they'd run off chasing those horses. But if they drank too late, that cavalry feint might not be a feint! [Answer] Shock troops used to break enemy lines. The lack of self-preservation leads to high casualties on both sides, but can create a path through enemy lines. Unlike in another answer, the unit wouldn't be particularly good for defense, because they'd be prone to engage the enemy outside of a defensive position, attacking the enemy when they should wait for the enemy to attack. They'd be most effective when they have easy and quick access to the enemy, e.g. open field or light forest. But they could also be used to rout enemies in defensive positions by swarming the enemy. Basically any situation, where a sane person wouldn't even consider attacking. [Answer] The only advantage I can figure is the "shock and awe" effect on unprepared opponents, more or less what it was achieved the first time war elephants were employed against the roman army. If the opponents lose their cool and break the line, your mad men can have an easy target to pursue. If they don't fall for the bait and refuse to engage battle, they will end up against their own mates, since you state > > They barely recognize friends from foes and, due to their excitement, they have a difficult time refraining their pulses to charge the enemy > > > Not too different from the movie version of the Orcs patrolling the tower outside of Shelob's lair in the Return of the King, which end up slaughtering each other over a quarrel for Frodo's vest. [Answer] You're basically asking about the tactical use of agents that have sacrificed self-control, and might, just as likely, harm their allies? This actually has some historical precedent in zoological warfare. In the Roman Empire (particularly late Roman Empire), war elephants were effectively tanks. Conventional militia and even the days' equivalent of artillery was particularly weak against them. However, the capability of an elephant on a battlefield was directly proportional to the control that the rider kept over it, and elephants had specific psychological weakness. No, I'm not talking about mice. I'm talking about herds of pigs, lit on fire, and unleashed on the battlefield. The pigs are fast, they were already very compromised, and they were extremely dangerous to the elephants. We're talking about mobilized flaming fat. They're not unlike your proposed berserkers, though they clearly weren't expected to make it through the fight. However, you need to remember that the pig was already soaked in flaming lamp oil—probably olive-based—just as your berserkir have already downed their rage-inducing drug. For what they did after being lit, all bets were off and to prevent blowback, the armies structured themselves to avoid the pig's potential trajectories after being set ablaze. (There were plenty of cases of the fire-pigs backtracking into friendlies, but they were a near-certain way to break the invading elephants.) As another, likely even closer, parallel, during the Roman invasion of Celtia, the Celts had borrowed a few tricks from the Vikings, such as the ingestion of drugs such as amanita muscaria (a hallucinogenic mushroom), hyoscyamus niger (a form of henbane), and copious amounts of alcohol to induce their war state. They were up against highly trained Roman soldiers who had conquered, basically, the rest of the continent; but in this drug-induced trance (much like your berserkir) they could take maybe eleven or twelve arrows to the chest and keep swinging. (Needless to say, much like the aforementioned elephants, this scared the hell out of the Romans.) The notion, much like for the pigs, was that they weren't returning home that night, and if they were it was a small miracle and likely a great shame. They had the solitary goal, not of saving their own lives, but saving their clan and family. (Heavy intoxication certainly helps with a move like that.) While downing hallucinogens before battle certainly has its risks and downsides, it also effectively made them pain-proof. Modern militaries do much the same thing with amphetamines, but now it's generally to keep soldiers awake for an extraordinarily long time rather than to drive them into a deadly trance. Sure enough, the Romans ended up retreating and actually built a wall bisecting the Celts from their more mild-mannered southern neighbors, deciding that even economically, Scotland just wasn't worth it. I suppose the TLDR is that, given proper strategy, an out-of-control supersoldier like your berserkir is treated much like an explosive device. They are unnaturally powerful and will likely get the job done, even though they may die in the process. The downside to them potentially breaking ranks can be mediated with spatial buffering. Traditional notions of morale no longer apply, but it's still quite usable. [Answer] ## Give the Drug to your Whole Army ...but only take it as a last resort. As others have pointed out, guaranteed moral is very valuable in a pre-modern battlefield, but disorganization is just as bad as poor moral. There are many historical cases where much smaller armies have ravaged their opposition just by making them unable to maintain proper cohesion; so, taking the drug is just as likely to lead to a devastating defeat as it is an unexpected victory. So, the only time you would take the drug is when defeat already seems certain, and you have nothing left to lose. Hearing the order "go berserkir" would be the equivalent to a modern soldier hearing the command "fix bayonets". No modern solider EVER wants to be in a situation where a bayonet charge is their best option, but sometimes desperate times call for desperate measures. [Answer] The most reasonable, likely, and historically accurate answers to this question: 1. Morale breaking: Barbarian versus barbarian (low-organization) armies generally clashed for short periods of time and winning consisted of one side becoming psychologically convinced that they were going to lose, cause a chain route. The routing force loses more casualties in the route than the battle. Who breaks first is almost entirely (typically) based on morale (how the lowest common denominator of troops feel about their chances of success). Once the lowest common denominator of troops become scared, or convinced that they will lose, they run, and then the people next to them run, and then the whole army runs. Berserkers (insofar as they existed) are designed to scare the lowest common denominator; size, ostentatious aesthetics, and lack of fear/humanity. You don't need the whole army to be convinced they will lose, only the lowest morale soldiers, or the ones specifically fighting opposite the berserkers. The troops facing the berzerkers run, or their pre-battle displays convince low denominator soldiers across the whole frontage to lower their morale, and you win. Fear of the men standing next to you deserting you, allowing you to be killed from any direction is the primary factor causing a route; you don't want to be the last one to run. 2. Berzerkers, large warriors with large weapons, with experience, could be useful breaking up shield formations, especially of more organized armies. Barbarian armies do not have the endurance of organized armies (like Romans) and have to achieve victory early or not at all. Having grouped or distributed men who are more effective at dislodging shielded soldiers from shield walls, removing/breaking shields, or causing spacing in the shield wall through extremely violent melee in order to get inside the formation and break it/route it was a key to victory. Notes: Berzerkers may be over-hyped and there are versions of this in multiple cultures. Ultimately there is a lot we still don't know, or are certain of regarding how groups of men conducted themselves in the killing of other men on the battlefield. I'm a tattoo artist and part time zoo keeper. Proof reading is for nerds. [Answer] ## Berserkirs are for Pinning the Enemy The key is to pin the enemy, and then use their lack of mobility against them. ## The Wheel About Your army consists of: * 70% main army (A) * 20% berserkirs (B) - placed on the far right * 10% reserves (R) ``` E E E E E E E E E E A A A A A A A B B R ``` Have your center fall back under pressure, as the right goes berserkir and stands fast. Your reserve shifts right. ``` E E E E E E A A E B B A E A E A E A E R ``` Obviously, your berserkirs are in a rough spot - outnumbered and unsupported. But that's fine, this is what they live for. The rest of the main line is tired from fighting, but holding. Your reserve, though, is fresh, and has the enemy main line FLANKED. The reserve smashes into the rear / flank of the enemy's left. That section of the line fails under the extreme pressure, and the rout begins. You roll up the enemy's line, and then finally relieve the berserkirs. ``` E E E E E E A A E B B A E A E R A A ``` At no point are your troops in any real danger from the berserkirs, and it makes good use of their fanatical state. If the enemy tries to bypass the berserkirs, then the closest people for the berserkirs to attack are... the enemy's rear ranks! You can do many variations on this. A favorite might be: ## The Agincourt Your berserkirs hold the enemy in place at the bottom of a hill, while the rest of your force rains indirect fire from the hilltop. As long as the berserkirs can stay close together, good enough archers can probably avoid hitting them most of the time. The risk here is the enemy retreating out of arrow range, and the undisciplined berserkirs following. Best mitigation would probably be to keep the main force close, with the understanding that an enemy retreat would initiate a general charge. Perhaps your main body knows to move to the left as the come down the hill in this case, setting up the conditions for The Wheel About on the fly. In any case, the enemy is going to have to reform their lines while under pressure from murderous berserkirs, which is not a great place to be. [Answer] In my personal opinion, berserker troops should be used as support for the infantry to flank and distract the enemy, as well as destabilize/destroy choke points in the way of the infantry if war engines (catapult, trebuchet, artillery etc) are not available. Remember, the infantry is the backbone of any military and must be prioritized above all else. It wouldn't be that expensive to add drugs to their kit, but it would weaken them when they're coming down, as amphetamines cause the user to become tired after the effects wear off. Considering that drugs have been developed in your alternate history, sneaking [hallucinogens](https://www.drugsdata.org/view.php?id=7623) or morphine into the enemy's food/water supply would be a useful tactic. [Answer] There's a lot of good answers here, but I think one overlooked one is that a surprising number of soldiers won't even kill the enemy under normal circumstances. If taking the drug makes all of your soldiers willing to kill it would probably make them unstoppable (in battles) until they fall apart from PTSD. ]
[Question] [ After the time travel designs from the [CASH WHEN YOU NEED IT YESTERDAY](https://worldbuilding.stackexchange.com/questions/185266/cash-when-you-need-it-yesterday-delivers-cash-yesterday-via-time-travel-but-h) business was stolen by a corporate spy, Amazon now has time travel capabilities. Of course, saying that they could deliver the packages yesterday puts them in the same legal kerfuffle as the cash loans company, so they decided to go with instant delivery. Here's how it goes; * Bob the customer clicks the purchase button for something that is bought off Amazon, choosing instant delivery. * Bobby the delivery driver gets a thing saying 'deliver this thing to Bob at this time' on their delivery schedule. * Bobby hops in the special time travel truck with the package. * Bobby drives to Bob's house, taking 1-2 days like normal shipping. * Bobby pulls up to Bob's house and pushes the time travel button. * Bobby exits the truck with the package 5 minutes before Bob clicks buy. * Bobby knocks on the door after Bob clicks buy and delivers the package to Bob. * Bobby goes back to their truck and pushes the time travel button again, travelling to three seconds after they left. * Bobby drives back to the Amazon warehouse for their next package or continues on their route. Now Amazon can't be causing paradoxes left and right because that's bad for business and they might get in trouble, so they need to make sure this delivery method doesn't cause any paradoxes. Amazon also wants to avoid secret code sending to your past self, like was mentioned in a few of the cash loans answers. Does Amazon have a good delivery system for avoiding paradoxes and secret messages? [Answer] This is totally doable! With of course the usual mind-bending that comes with time travel. So the fun thing about paradoxes is that they only happen if you allow them to happen. However, if your time travel system disallows them, then by definition they won't happen. This requires closed-loop time travel. This simply means that any form of backwards time travel has already happened and its effects are already seen. This means, that, for example, you cannot travel back in time to kill your previous self (at least not successfully). This is because for your future self to exist, you must have avoided getting killed up to that point. Clearly, since this is a universe where your future self exists, this must be true. There are some ramifications about fatalism and the effect of choices in a universe like this. Because time travel is allowed but paradoxes are not, the amount of things that are possible go down. If you get handed a million dollars by your future self, you know with absolute certainty that you'll survive, acquire a million dollars, and travel back in time at some point in your future. Although there are still a bunch of other fun uncertainties to play around with. Back to your specific example: this works really easily for a delivery service! You simply have an app that queries if the package is nearby the moment the user tries to order it. If it's not, we already know the package must have been lost before the customer even orders it! So you can just disallow those purchases with an "out of stock" or "internal error" or what have you on the app itself. Building a world like this just requires reordering your steps: 1. Bobby2 appears seconds before the delivery date with a package delivery. 2. Bobby2's time machine truck notifies headquarters of arrival. 3. Bob tries to order a fancy pair of mittens. 4. The ordering software checks and sees that Bobby2's truck is in position with the package. 5. Bob's order goes through. 6. Bobby2 walks up and delivers the package to Bob. 7. Simultaneously, Bobby1 gets an order to get a package of fancy mittens, gets in his time travel truck, take it to Bob's house, and time-travels back to the exact time the software has given to him. 8. Bobby1 takes his time doing all of this. 9. Simultaneously, Bobby2 is allowed to take future orders or do whatever he wants. 10. Eventually, Bobby1 travels back in time, becoming Bobby2. Note that this means that there will be 2 Bobbys walking around until Bobby1 finally time travels. From his perspective, he goes back in time, but from time's perspective, there's simply a span of time where 2 Bobbys (and 2 time travel trucks!) exist at once. [Answer] It will create a nightmare contagion tracing feedback loop. Let's say Bob orders a package to be delivered, and over the day or two it takes for Bobby to drive to Bob's place, Bobby is exposed to a contagion (Covid, chemical attack, zombie virus. Let's go with zombie virus as it's more fun). Bobby then travels back in time, dragging the virus back in time as well. Now the contagion outbreak event occurs three days earlier than it did in the first loop. Bob, happy with his purchase, immediately pops over to the shop and interacts with another delivery driver who is just about to travel back to deliver a package to Bob's neighbour Alice three days before then. Now the zombie virus is even further back in time. Alice's outbreak actually makes waves in a bad way, and Bob never got round to making that initial order. Two questions result: * Does the zombie virus outbreak still occur? * How do medical personnel track, trace and more importantly contain the origin of the time-shifting outbreak? [Answer] How do you deal with holdups? And the duplicated packages? Say Bob orders the item, Bobby drives to Bob's house, does the time travel and hands him the package, then returns to normal time an drives off. Problem is Bob now knows that in a couple days Bobby will be driving up with a package containing the item he ordered. What happens if he steals the item before Bobby delivers it? For the time it takes Bobby to deliver the package, there are two instances of the package in existence. [Answer] # Minority Report style predictive delivery As mentioned by others, there's no way to muck with causality and avoid paradoxes. Even the simplest "send one bit back in time" leads to all manner of weirdness. Fiction writers rectify this by all manner of handwavium, but personally I'm a hard-sci-fi fan and like to minimize the unobtanium and contradictions. Don't bother with sending the whole truck back in time - send information instead. Just employ precogs which are so good at knowing users' needs, they can dispatch the delivery before they decide to order. "Precog" as a time-travel mechanic has a wonderful anti-paradox escape hatch built in. It's imperfect. So if you ever deliver a package that was never intended to be ordered, Amazon can just say, "Are you sure you didn't actually want this? Given how easy it is to return stuff anyways, it's trivial to just send the delivery back. [Answer] It causes a paradox if Bob does not then click buy five minutes after recieving the package. Would be better and non paradox causing if Bobby time travelled to five minutes AFTER (or immediately after) the package was ordered. [Answer] Yes, yes The paradox seems pretty much solved. Unless the customer is actively trying to break the universe, like hanging a camera to see if the guy is going to bring the package, it should work fine. Even so I would recommend to have the delivery truck arrive at the moment the message arrives on the servers. This way the act can't be taken back. A paradox can still happen if the guy tries to mess with the delivery chain, but should be difficult to do for most persons. The secret message thing is also solved with the above. If it only arrives after your click, you can't give yourself information about the future. But if you still have the package delivery arrive earlier, you can have a message already. As in 'only buy stock x when truck arrives'. Just wait behind the computer with stock information and Timazone open for the purchase. The moment you spot the truck, the message is received. 5 minutes later whatever you check on will go up/down. Get or sell the stock at that moment, buy the thing 5 minutes after. Currently there are traders making millions on being the first to know/do something in miniscule timeframes. Milliseconds and less. Imagine what you can do if you have information about 5 minutes ahead. [Answer] Another problem, which isn't really a paradox, is that the time-traveling delivery guy can't know whether the road is clear in the time he's traveling to. What if he drives into an empty parking spot, but that spot is not free when he hits the time travel button? [Answer] Yes, there is a problem, it is inevitable that a someone will figure out a system to encode information in the delivery request so that they can make a killing on the stock market, or whatever they need to do. How would this work? You need an insider who is able to view the delivery request in the past before it is shipped, this could also be the buyer, or they could be partners. They could be monitoring a portfolio of stocks for movements and when a big event happens, immediately make an order that encodes how to bet on the stocks. This could be based on what items they are buying or the address, or the 'notes to the driver' or whatever. This information will be transmitted into the past where the insider see it and takes the appropriate action 1-2 days before the event happens. Now, forget money. What if the insider is a plant by the CIA or some other nation state who want to monitor world events in the same way and prevent the future occurring as it should. It seems far too tempting for someone to do this or similar schemes. [Answer] ## Any time travel is open to paradoxes and that is fine Just go to the TV Tropes page of any movie involving time travel and look at the Headscratchers and Fridge Logic sections. There is always some theoretical possibility that lets the world building seem lacking at first glance. However, your goal as a story teller isn't to world-build a time travel mechanism that works flawlessly in all possible situations. It is to create one that doesn't leave any obvious loopholes/headscratchers in the situations that your characters face in the course of the story. So in your case the question is, what role will instant delivery play in your story? If it is just an excuse to get stuff to the characters fast, it is definitely good enough as you described it. If for example a character plans to hijack instant delivery for a heist, you need to harden the mechanism for that application. [Answer] Rule #1: There are no universal laws for time travel, only mathematical speculation. Rule #2: The rules of time travel are (thanks to Rule #1) 100% in your control. Rule #3:: If you choose to not set rules, then there is no such thing as time travel that doesn't cause paradoxes. One could reasonably assume that it's possible to minimize paradoxes through protocol and procedure — but it's impossible to avoid them all. You'll notice that I've not said a thing about your presented scenario. I don't need to. It'll work if you want it to. It won't if you don't set time-travel rules to fix the problems. But I will use an example of what can go wrong. You have the following four steps: 1. Bobby pulls up to Bob's house and pushes the time travel button. 2. Bobby exits the truck with the package 5 minutes before Bob clicks buy. 3. Bobby knocks on the door after Bob clicks buy and delivers the package to Bob 4. Bobby goes back to his truck and pushes the time travel button again, travelling to three seconds after he left. Where can things go wrong? At any time during steps #2 and #3. Bobby has days worth of time where he can go do anything he wants - including leave for Europe and never be seen again. Pardoxes abound! Unless you don't want them to. * You could declare that time is self-healing. After step #1 there are two bobbies. Who cares? If they meet, so what? The fact that the recipient got his package is now a part of history and if future-Bobby convinces present-Bobby to not go to work that day, what really happens? Nothing. Although nobody having told Amazon that the package had been delivered would technically cause Amazon to send a second* package back in time. Hey... you could make a fortune by killing Bobby at the door and selling future-truck and each succeeding copy of the product you receive! Bobby keeps showing up. You kill Bobby. Amazon isn't informed so they send another package.... And since nobody in the recipient's timeline is missing Bobby....* There's no paradox because time is self-healing. But your world (or a portion of it) might find itself stuck in a time-loop until the recipient gets bored with killing Bobby. * You could declare that time abhors a vacuum. In other words, whether Bobby hits the button or not, he (and the truck) will eventually be yanked back to the future because something's missing in the future and the future wants it back! Dang, that means the package will be yanked back, too. OK, this one doesn't work. But it would stop Bobby from heading off to Timbuktu to do what he wants for two days. * You could declare that time stops until the loop is resolved. There is no progressing future until Bobby hits the back-to-the-future button. This would work no matter how many trucks are in motion. Unless the recipient kills Bobby. Then there's no restart to the future. I'm thinking the Langoliers here leading to a new Big Bang. Maybe that's too much power to give to a recipient who's frustrated with Amazon's shipping policies. --- On the other hand... Why are you trying to remove all the paradoxes? The paradoxes are the point of every time-travel story because they always engender moral and ethical crises. If we're assuming you can't avoid the paradoxes, then you're left with Rule #3, right? 1. Amazon's trucks are outfitted with time-stamped GPS-enabled transponders that know how to account for the shifts in time. In other words, when one of those trucks pops up in the past, the then-present Amazon knows this! Ah-hah! Somebody's about to push the "Buy!" button! But it also means Amazon's Department of Temporal Protocol and Affairs is now watching Bobby very carefully — because the last thing Amazon wants is for Bobby to think he can pop off to the local gentleman's club for a quick glimpse on company time — because all time is company time (and it's Amazon's!). In other words, Amazon's DTPA will be quick to get on the walkie-talkie and remind Bobby to push the darn button! Time's a-wastin'! 2. Amazon has an entire warehouse full of the most secured computers in the universe that manage and handle tracking of time-travel. Bobby isn't allowed to move that truck two inches after traveling to the past. In fact, Bobby has a chip behind his left ear that lets Amazon track him, too. No grandfather paradoxes here, thank you very much! Truck... button... door... Thank you!... truck... button... or we hunt you down like the mangy dog that you are and nail you to a sour apple tree, Bobby! 3. Of course, nobody knows how Amazon is achieving their incredible record for on-time (literally!) deliveries — except maybe Ford Auto, from whom Amazon buys its trucks. Ford started wondering when Amazon's truck purchases suddenly went up 20X. When Ford investigated, they discovered that trucks that normally took 20 years to look run down, beat up, and over-repaired where rolling out of Amazon's fleet control center looking that way after only a couple of months. So, Ford knows what's going on, which is why Amazon's shipping costs went up — to pay the extortion bill. And we won't even mention why Bobby, who was once thought of as an intelligent young man, would allow himself to work at a job that would age him 50% faster than normal.1 4. Which is why Amazon modified their trucks so that the whole truck doesn't go back in time. Only the package and a drone do. Bobby pushes the button and the package disappears and the drone shimmers for a moment — the drone having dropped the package off and pushed the door bell, then returned to the future. The drone company's on the take now, too, but that's offset by the reduction in pay to drivers for the fact that they were dying at age 50 rather than age 90. Conclusion The truck and Bobby don't travel through time. A drone, which is controlled in the past by the Amazon DTAP, and the package do. Bobby just waits for the drone to shut down in his truck and drives away. --- 1 OK, not 50%, but faster. You know what I mean. Who would take a job that shortens their life? [Answer] In short, it creates a lot of problems and wouldnt work. In long: There is no way, not a single possibility, not the sightest of changes to travel backwards in time in or Universe with or Laws. The main reason for that is not even Causality although it is a big part. It is Energy. If you go from the Future, your Present, to the past, you add Energy to this new time while removing it from the present. This breaks conservation of energy as the Energy dosnt get converted, it is just gone. And then comes out of nowhere. Which again, cant happen. So this puts a hard stop to the idea right of the bat. Causality then punches you while down, even the Atoms of your Body interacting with the Air around you break Causality. Because an Event from the Future changed an Event in the past. So you just standing there breaks it. I suppose you could go back in time if you had no Matter or Energy and wouldnt ever interact with anything at all. To make Time Travel work you have to change the Laws of Physics. Which honestly isnt that hard to do because you can just bs something at the Macro scale that Magically solves your Problem. Idk, say that something like Retrocausality exsists. Like you can go back in time and do everything, dosnt matter. Causality now works both ways. It dosnt here but hell, if it would we wouldnt know. [Answer] I think your biggest problem is taht your customer will always cancel their order. "Instant delivery" definitely isn't free for your company, time travel probably costs energy, so your customer has to pay extra for this instant delivery and certainly will cancel it if it doesn't arrive on time. So now we have to ask how time travel works in your universe, as far as I know there are mainly three ways: * Directly affecting the past (Back to the futur I): there's an "original reality" that you change by traveling back in time, but in that original reality your customer didn't receive their package on time, since you hadn't traveled back in time yet, so they cancel their order * Alternate realities (Back to the futur II / Terminator): you don't change your universe but create an alternate reality, or simillarly traveling back is just hoping to a parrallel universe that lags behind yours in time. In that case you're immune to paradoxes anyway but there has to be a "first universe" and we fall back to the previous case, at least in that case only your first-universe-company will fail, the others will have some time when they indeed work * Loops (Harry Potter 3, and a bit weird so only makes sense with magic): there is only one reality and time-travel is possible only if it creates a more stable loop than a universe where it doesn't happen, so in your case the loop decribed (order by the customer -> instant delivery -> order stays up) is stable, the problem is that the customer canceling their order also is a stable loop and doesn't require time-travel (in which case there is actually no loop) [Answer] Yes, it can be done and it will be (mostly) safe. First, forget about sending Bobby back in time. The machine is really big, not to mention expensive to give a portable! one to every delivery guy working on minimum wage (and Amazon wouldn't be able to ensure they don't telly anyone about the time-travel nor they actually take advantage of that for personal reasons). Instead, Amazon will have the purchase request travel back in time. As the won't receive it before ordering, the timeline is preserved, avoiding paradoxes. Today it's 22nd October and the customer wants to buy the iphone xxi. This would usually have taken 5 days to deliver. In fact, Instant delivery wasn't offered as an option for the first 5 days. When the customer clicks Purchase: * The request travels back in time to 17th October * A normal delivery is routed to the customer house, taking 5 days * Bobby has no idea that the request originated in the future * Bobby will stand at the provided position by the delivery with the iphone xxi. When the customer completes the request his pda/smartphone will update with the details and Bobby will just ring customer bell seconds after purchase. An excellent so that customers don't have time to change their mind! Another answer mentioned that this could be done with precogs, but there is no need for that. In fact, Amazon is already doing this. When their AI algorithms/precogs/time-travel purchase order state (or "estimate") that there will be X purchases of iphone xxi from your zone, they will distribute their stock accordingly, so they will try to have that in a warehouse near your region/city. That they have a delivery guy standing next your door or already on your neighborhood is just the next step. For anyone questioning it, Amazon official reply is that they use state-of-the-art Artificial Intelligence algorithms to predict the sites where a new iphone xxi will be bought and provide a better experience for their customers. From the delivery department, it doesn't really matter from where those predictions come, as long as they are accurate: * they might have a complete profile on you and, knowing you better than your own mother, know that as soon as you receive your check (at day X), you will be buying the new iphone X * they may have time-travelled the purchase order * they could know your intent (or wishes) to buy an iphone xxi from conversations between third parties that ~~they eavesdropped~~ their Home Assistant used, in combination to many other data downloaded from the cloud. * Amazon could have just showed the gullible customer, as planned, an ad for the iohone xxi Just remember, if anyone asks, it's just an AI. Customers will find creepy the accuracy of our results, but we have here another order they perform in an hour, showing they will continue working with us. [Answer] The amount of paradox in this situation is endless: Bob the customer clicks the purchase button for something that is bought off Amazon, choosing instant delivery. Bob could changes his mind, cancel his order and go for a walk, encountering the delivery worker who just got out of his truck is one. Bobby the delivery driver gets a thing saying 'deliver this thing to Bob at this time' on their delivery schedule. Unless the delivery event info is stored locally on his device, it will not exist in the delivery database when he travels back in time. Also, this does not account for past Bob changing his mind and cancelling the order, also leading to problems. Bobby drives to Bob's house, taking 1-2 days like normal shipping. Wait, we've normalized time travel but not teleportation? Pretty sure we'd have teleportation or at least drone delivery perfected by now... Bobby pulls up to Bob's house and pushes the time travel button. This very action and all those following are now creating endless alternate theoretical futures. Bobby may accidentally scare Bob's cat, Roberta, by materializing into existence in front of her. She stops chasing the mouse she had been chasing which had accidentally ingested a diamond, and said mouse would have been a ritual gift to Bob, who, upon investigating, would have found the diamond inside, taken it as a sign that he can now propose to his girlfriend, now having a stone to set in a ring he added to his wish list but had decided against, and this delivery was the ring he had chosen instead. Bob's girlfriend, Gertie, instead of giving up on Bob because he's taken too long to commit, decides to marry him and start a family...and that is only one of an infinite list of alternate future universes for only one individual this action would affect, not to consider the ecological impacts if Bobby accidentally materializes on top of the last endangered Gypsy Moth, wiping the species out forever... Bobby exits the truck with the package 5 minutes before Bob clicks buy. Bob cancelled his order 4 and a half minutes ago, but Bobby doesn't know yet because the delivery order can't be updated from the past due to certificate errors with the delivery API due to time differences. Bobby knocks on the door after Bob clicks buy and delivers the package to Bob. Bobby has had 5 minutes to create more paradoxes and butterfly effects than any current supercomputer could track... Bobby goes back to their truck and pushes the time travel button again, travelling to three seconds after they left. If a random hit and run driver totals Bobby's truck, he's not getting back to the future any time soon, and by this time the universe has imploded because Bobby cannot exist in the past without changing the future. Any sustenance he takes will not be available for the individual it was 'destined for', leading to even more butterfly effects, not to mention any personal interactions he may have such as meeting someone new and causing new and complex relationships to both cease to exist or come into existence. Bobby drives back to the Amazon warehouse for their next package or continues on their route. Oblivious to the irreparable damage he has done to the present and future, Bobby continues on his way, never meeting his future wife, Gertie, because she never moved to San Francisco after deciding Bob had gotten cold feet and was never going to commit. The Gypsy Moth, having been mankind's last hope for cloning a new generation of species that depended on the moth's special genetic traits, is now gone, and in despair, one of (insert nuclear superpower here)'s top generals convinces one of his fellow generals to help wipe mankind out by initiating nuclear missile launches. [Answer] How about combining doing the shipping in the past with making the time travel system unreliable? Then you get a list of potential orders, which may or may not be clicked, but you don't know whether they would have if you hadn't shipped them. And then compensate for the unreliability with informing the driver at point of delivery whether to deliver the package, using fast but causal communications. (For all practical purposes, 5min = instant when we are talking delivery). The extra undelivered parcels would be compensated for by the drop in failed deliveries due to people not being home. [Answer] I still say that any time travel method that allows the past to be changed, WILL NOT be invented. Not that I think its impossible, simply that it will inevitably destroy itself. If you CAN go back in time and change the past, then inevitably at some point, somewhere in the universe it will be used to change the past such that time travel is never invented. As long as time travel exists, its containing universe is unstable. As soon as time travel's changes cause time travel to never be invented, the universe solidifies into an existence where time travel is never invented. So. The above scheme does include the possibility of a disgruntled delivery worker going to the past and preventing the invention of the timetravel, thus until that happens that universe is unstable. [Answer] Yes, it does cause paradoxes. But we can avoid paradoxes, we can make time-travel technically possible, but practically of no effect. Frame challenge. Businesses that claim to utilize time-travel for delivery are scams. Time-travel is technically possible, but practically useless, as it happens only on quantum level, under very obscure circumstances. The general public doesn't understand these nuances, they are overwhelmed with cheap sensationalism about proven possibility of time travel and strong associations of time-travel with "Back in the Future"-like shenanigans. This lead to creation of all kinds of unsavory businesses that claim to utilize this revolutionary technology, but in reality just scam people. [Answer] Bob can (slowly) destroy the Earth! 1. (Evil) Bob moves to the top of a high cliff 2. Each day at mid day, Bob orders as many heavy as he can afford. 3. Bobby arrives from the future with the heavy packages 4. Bob immediately drops the packages off the cliff. Accelerating the earth towards the sun! 5. 2 days later Bobby drives up to the top of the cliff with the heavy packages, But crucially it's not midday and the Earth is 2 days further along in its orbit of the sun. The Earth is pushed in a random direction. Essentially here your time travel machine glosses over the problem of appearing in the same place when it travels backward in time. In doing so it violates conservation of momentum and hence energy. ]
[Question] [ In my world I have a big region that annexed four others in just two years by using strong military strategies and propaganda. They manage to maintain this forced union using their religion, which is the most developed one and that gives religious explanation for unexplained phenomena. Then my question is: Could it be possible for those 4 regions to accept this religion in ten years or less? Some clarification: * It takes place in a medieval era. * The other regions have some beliefs but theirs are more primitive and disparate. * The other regions have less developed militaries, however they are not under-developed, they are only more pacifistic. * The religious education is really strong right after the annexation. [Answer] > > The other regions have some beliefs but their are more primitive and disparate. They are more pacifists. > > > Those two things are contradictory; pacifism is more advanced. Nearly all animals (including humans) have a natural inclination toward violence for securing their "survival goods" (food, water, shelter, hunting territory); it is why we have been at constant war in one place or another for literally all of history. A pacifist nation has a moral philosophy against the use of violence, which your aggressive nation does not have. That points to a cohesive (not disparate) and advanced (not primitive) religion, like Buddhism or the "turn the other cheek", "give him your coat", and "render unto Caesar what is Caesar's" form of Christianity. I would not assume your pacifists are just cowards, afraid to fight. That is contrary to human nature, especially the behavior of young men that are more rebellious and ready to prove themselves to win status and females. (I am not being sexist; this is basic human psychology across many cultures.) So unlike other answers here, I will be contrarian: I think your setup makes it much less likely a region will convert in the time frame allowed. People that subscribe to pacifism so strongly they'd rather be conquered than fight are not going to ditch that for a new religion that allows violent coercion in just 10 years. Violent coercion is what they have been regarding for a lifetime as primitive, it is why we call such violent conquerers "barbaric" and "brutal" and "beastly". # How to fix it. Get rid of the pacifism. They can be fractious tribes with poor organization and mistrust of each other; with perhaps uneasy truces between them. Each tribe can have its own local versions of religious beliefs, including the knowledge that they are the only few thousand people that believe their particular version, making it much more likely, after being militarily conquered, that they will ditch their religion and 'join the crowd', believe what the hundreds of thousands or millions believe. As for the conquering nation; they can equate openly preaching heresy (against the State religion) with rebellion that is punishable by death. They don't have to punish private practice at all, and can even say so: Religions whither and die quickly if they cannot be publicly practiced; for a variety of reasons in human psychology, including wanting to fit in socially. If everybody is going to church for the State religion, others want to go too. Whatever religion exists in the conquered regions to start, make it actually primitive: violent, bloody, and above all, fractured into a hundred similar but disagreeing factions in different towns and regions, even to the point of mutual hate or demonizing each other's beliefs. This will make them reluctant to put aside their differences, and thus too slow to cooperate in repelling an invader. You implement something like this, from [Martin Niemöller:](https://en.wikipedia.org/wiki/First_they_came_...) > > First they came for the Socialists, and I did not speak out— > Because I was not a Socialist. > > > Then they came for the Trade Unionists, and I did not speak out— > Because I was not a Trade Unionist. > > > Then they came for the Jews, and I did not speak out— > Because I was not a Jew. > > > Then they came for me—and there was no one left to speak for me. > > > It is poor writing to make things too easy; were I writing, I'd make these battles costly and bloody for the conqueror. They would win, but I don't want my reader bored, the reader needs to think the conqueror may be overreaching, and could run out of soldiers. Pacifist religions tend to make a virtue of subjugation and non-violence, one that will be rewarded in the afterlife, while violence in general will be punished in the afterlife. So the pacifists see their aggressors as ensuring themselves a lifetime in hell, while their own pain and suffering under the heel of the oppressors is guaranteed by their Gods to be temporary, they will be with their kind in Paradise, free and living in peace for eternity. This is a belief in Karmic Justice; the bad guys get what they gave a million times over. They won't give that belief up just because you are abusing them, that would make them the bad guys. On the other hand, if their religion is already violent and they already believe in the principle that "Might makes Right", then your wars are more violently entertaining, and it is believable that, *because* Might makes Right, the conquered adopt the religion of the conquerors, because clearly the conquerors religion led them to victory and their own religion led them to defeat. [Answer] ## How the Romans avoided this problem The Romans had a very practical system to work around this problem; we call it the [interpretatio Romana](https://en.wikipedia.org/wiki/Interpretatio_graeca). Basically, what they did was pretend that the religion of conquered people (and of allied people and in general of any new acquaintanted people) was "essentially" the same as the Roman religion; the alien gods were assimilated with Roman gods, and all the practical aspects of the alien religion were simply left in place as being merely local variations. The best known example is the notional equivalence of Roman and Greek gods and goddesses; we all "know" than Minerva is the Roman name of Athena, Juno is the Roman name of Hera, Venus the Roman name of Aphrodite, Jupiter the Roman name of Zeus, Mars the Roman name of Ares and so on. This gives people a fuzzy sense that the Romans and the Greeks had the same religion, and this was the actual officious position of the Empire. (There was no "official" position. The Roman state scrupulously avoided saying anything official about any non-Roman religion.) In reality, of course, Mars and Ares, Minerva and Athena, Venus and Aphrodite are profoundly different divinities, and the purely abstract Roman religion couldn't be more different than the anthropomorphizing and luxuriant Greek religion; but politically the position was that the two religions were essentially the same and that was that. Similarily, Egyptian deities, Gallic deities, Germanic deities were given officious Roman equivalents. (For the curious, Odin is officiously the same as Mercury, Thor is just a barbarian name of Jupiter, and Freya is of course Venus; this is plainly seen even today in the names of the days of the week -- Mercuris dies is Wednesday, Jovis dies is Thursday, Veneris dies is Friday.) So in general the religious assimilation of a newly conquered province in the Roman Empire was a no-operation: of course they had the same religion as the Romans, they just used some specific local rituals and had funny names for the gods in their barbarian tongue. The one province where this did not work was Judaea, where the locals worshipped the One True and Jealous God Yahweh; we all know where that went -- three bloody rebellions, Masada, the destruction of Jerusalem, and eventually the hostile takeover of heaven by this new provincial god. To clarify some questions implied in the comments, this was entirely a one-directional process. The Romans saw the Greek gods Hermes and Aphrodite, or the Germanic gods Odin and Freya, as equivalents of the Roman Mercury and Venus; this does not in any way imply that they required the Greeks or the Germans to use the Roman names, or to somehow fuse the local cults with the imperial cult. Moreover, whenever a local divinity was just too alien to be assimilated with a Roman divinity they left it as they found it. For example, both the Levantine goddess Cybele and the sister and wife of the Egyptian god Osiris, She Whose Name Cannot Be Used on the Internet, enjoyed quite a bit of popularity in Rome, although they never made it into the state religion. ## Further considerations As for "maintaining this [political] union using religion" this is highly unusual. Religion is a very weak force in the political realm, and it is rarely if ever efficient at forming a basis for a political structure. No Christian Church, and not even the otherwise very cohesive Islam, has ever succeeded in transferring religious unity to the political realm. For suitably chosen values of "always" there have always been more than one Chistian political structure and more than one Islamic political structure. A "really strong religious education" is highly specific to the Abrahamic religions -- the Hebrew religion, Christianism and Mahommedanism. The religious education in ancient Greece and Rome was purely practical and done in the family; there was no such thing as a Roman (pagan) catechism, and they would have been very surprised by the idea. ## But wasn't the Catholic church powerful? A commentator requested an expansion addressing the apparent power of the Catholic Church. The short answer is that from the 5th to the 15th century the Church was powerful or at least influential because it was a large and well structured organization which provided a decent education to its members, who were quite often called upon to serve in the political structures; its power had little to do with the professed religion. The first observation is that the question is asking about a religion, not about a religious hierarchy. To illustrate the difference, consider that before the 19th century there was no doctrinal difference between the Catholic and Orthodox churches; they were clearly practicing the exact same religion. (Even today, they officially accept each other as fully holy and apostolic churches, and recognize the validity of the sacraments performed by priests of any of them.) But their hierarchies have been completely separate ever since the Great Schism in the 11th century. It is the hierarchy which had power (occasionally and regionally) and influence (for longer times and over larger territories). But such hierarchies are not the norm; today they exist only in some versions of the Christian religion, such as the (Eastern) Orthodox churches, the (Western) Catholic church, and the Church of England; in the Antiquity only the Hebrew religion had such a hierarchy; the ancient religions of Greece, of Rome, of the Gauls, of the Germans, did not have anything similar. The second observation is that the Christian religion did not do much to preserve the political unity of Europe. As in, it did nothing. Ever since the division of the Empire in the 4th century Europe has always been composed of multiple states, often at war with each other, even though they were all Christian. And eventually even the religion split into several variants, which for quite some time provided fuel to incomprehensibly cruel religious wars, until in the 17th century a silent consensus was reached placing religion firmly outside the political realm and strictly into the personal sphere. (That's why Europeans are baffled by the readiness with which American politicians speak about their religious faith. We know how dangerous this can be.) [Answer] Doing it in ten years will depend on how converted you want them to be, how much people you want to convert and how far you're willing to go. While in ten years you can easily have a majority of people accept the new god, you can't convert all of them. Furthermore, you can't really guarantee they aren't just pretend-converted. Fear works fast Fear usually works well to manipulate people. Torture doesn't get reliable information because people will say anything to get it to stop. On the other hand, people will say anything to get it to stop. If your goal is to make them say your god is cool and theirs suck, don't read any further. You could also genocide unbelievers for similar fear-striking results. It may be a fast solution, but it may also reflect badly. Particularly if your religion features "you shall not kill" as one of its primary rules. People might have a moment of brilliance, put two-and-two together and start revolting because your religion is hypocritical, so be careful with the executions. Lost in conversion The problem you face here is how genuine people are about your religion. Someone with survival instinct may show up for mass like a good believer, and then just sit their praying to their old gods in their head with a smile, and you wouldn't see the difference. Conversion is hard to force. It's hard to convince someone that the thing they believed for all of their lives is wrong. Forcing change on someone may have all sorts of reactions, like resentment and hate. Therefore, while force and fear may have immediate positive results, it could backfire later. Like they say, who lives by the sword, gets their head chopped. Change I may be going to be wildly anachronistic but bear with me. What you are asking for is change. And the oldest trick in the book of change management is: make them think it's their idea. Consider this: what if you just put your religion in the competitive space? Build new cool churches, and hold receptions with free food or whatever will get people to come. Your religion has an explanation for anything, you may hold a Q&A sesh where every question is awarded. You know you have the answers anyways, right? Make them compare your religion with theirs, and then make it so the comparison favors yours. They may not all come to the conclusion your religion is better, but some will. And since they'll think they came up with that, they'll believe much harder than if you just point a gun at their head. And the bonus is that it's a double whammy. Your religion will be there, projecting a positive image. Sometimes, you just have to repeat something until it becomes the accepted universal truth. That's what advertisement is, and it works. Your religion has to be there, it has to remind you that it exists, and it has to show that it is cool. I wouldn't go as far as advertising your religion as a new disruptive spiritual paradigm in the religious headspace, that might be a bit too avant-garde, but telling people that your god did it enough might just convince them he actually did. At worst, it won't be that foreign god that came out of nowhere, it'll be just a normal part of their life they don't reject. Non-rejection is actually a pretty good result. Total conversion Okay, but you still can't convince everybody, so what do you do with the rest? Nothing. They'll die off eventually. The ultimate long con isn't to change the present, it's to change the future, and future starts with the kids. That's why the Church starts indoctrination early always welcomes children. Although I guess it could also be for the diddling, but that's another issue. Kids will believe anything: Santa Claus, God, Disney princesses, that life is fair and they'll all be equal, etc. That's why any good dictator has to be on point with education. It's hard to convince someone that the thing they believed for all of their lives is wrong. And when that thing they believe is the thing you want them to believe, then it's a good thing. The kids will become adult believers that will teach their kids that your god is the best. They may even convince their parents because what they learned at school must be true. The side effect is you just created a religious dictatorship. [Answer] Well, why not. But here is the problem: This has happened multiple times throughout history. The Germanic and Celtic tribes, Rome, the Meso/South American civilizations just to name 5 (out of how many?). Every time they didn't just accept the new religion but basically created a new one that survived until this day. All the above accepted Christianity - sometimes rather quickly, 10 years is certainly not too short - and they stayed that way. But with this, Christianity also accepted them. I do not want to go into details, this is definitely worth your time if you want to research this, but I want to give a couple of examples: After the Irish Celts became Christian, they stuck to some pretty barbaric rituals (barbaric by any standard). In return, they send missionaries across Europe and established countless monastic traditions that were Pagan in origin. Of course everybody also knows about the South American people that accepted catholicism but to this day are worshiping their old gods hidden in the virgin Mary and similar instances. Something like this is true for any case I am aware of. Why do people celebrate Christmas? Basically because Romans became Christians. The Merovingian Franks accepted Christianity super quickly but kept some traditions like polygamy (one example out of many) for a century or more afterwards. Yes, you can convert your people in 10 years. This has happened with the defeated as well as the victors. But you cannot expect no feedback and no traces left of the old faith. Mostly people will follow the religion their current king is following. All this stuff you see on TV where there is always that one guy that "wants to stick to the old traditions" - well, that's TV. A very common way to do this is to marry their king to one of your religious daughters. [Answer] There are plenty of cases of this in history. The [Roman Christianity vs Paganism](https://en.wikipedia.org/wiki/Christianity_and_Paganism#Prohibition_and_persecution_of_Paganism_in_the_Roman_Empire) was a rather slow process whereas the [Spanish forced conversion of Muslims](https://en.wikipedia.org/wiki/Forced_conversions_of_Muslims_in_Spain) was quicker but still took place over thirty years (though hindered by the Pope making the Spanish king protect freedom of religion, not a problem that seems to arise in your case). In the end, though, each case is different. How devout were the followers before you tried to convert them? Do you approach it with violence and force people to change? (In which case you'll probably still have some underground worship). Do you try to spin it as an evolution of belief? It all depends on the religions and how compatible they are. Without very precise description of each faith I'm afraid all we can say is that yes, it could be as quick as ten years. [Answer] Religious education/brainwashing, when accompanied by supportive methods like exeecution/persecution of misbelievers can happen in the time span you envision. Also a conquerer with higher civilization can indirectly support adehesion to the new religion ("if our god Whatishisname could not protect us while their god Coolgod made them so strong maybe it is better to worship the Coolgod"). Definitely possible, then. [Answer] The simply answer is "Of course". The more complex is "naaah that depends". And it depends on size of the territory, the character of previous religion (if it's animism, sympathetic magic or personification of causes in humanoid form). For example Poland have switch to Christianity in 966. Well, the prince and his court have been baptised. Some regions didn't heard of this until XIV century. And their pagan rituals and belief just morphed into polytheism. And just 70 years later Bezprym said "You know, this Christ mumbo jumbo is bollocks, let's not go there, it's a silly place". And he send king crown to Emperor Conrad II so he was cool with it. Oh, and also in 1410 Poland had this big war about being real Christians with the real Christians that were real because they killed pagans. So in ten years some parts of the conquered regions could not even heard that they are conquered. [Answer] Looking at it historically, I'm hard pressed to think of examples where a conquered people have accepted the conqueror's religion like you describe. I can think of x cases: 1. Sometimes people of one religion manage to convert others through missionary activity. Christians have been very successful at this, converting people all over the world to Christianity. Sometimes this was done after or as part of military conquest, but quite often not. Buddhists and Muslims have also done this successfully. 2. Sometimes people hold on to their religion despite incredible pressure from the conquerors. The Jews are probably the best example of this. They were conquered and their nation was destroyed and they were scattered across the world, and there was no such thing as a "Jewish country" for almost 2000 years. Yet Jews kept their religion. 3. The conqueror might exterminate the local people and replace them with their own people. This is pretty much how Muslims converted north Africa and the Middle East. But no one is really converted here, the people who believe in the old religion are simply wiped out and their land taken over by people with the new religion. 4. As AlexP discusses, the Romans came up with the interesting -- and highly successful -- plan of merging their religion with that of the conquered people. They'd say, "Oh, you have a god of the sea that you call Poseidon? Why, we worship him too. We call him Neptune." This worked at least partly because the religions were similar enough that making these analogies might have been a stretch but it did not sound totally insane. This didn't work with the Jews because the idea of many gods and the idea of one God were just too far apart. You can say, "We have a god of thunder, a god of the sea, and a god of war. You have a god of thunder, a god of war, and a god of the harvest. So okay, let's put them together and then we can both have 4 gods." It doesn't work to say, "We have 100 gods and you have 1 god, so let's put them together and now we have 101 gods." And frankly, I think a big part of making it work was that the Romans did not care very much about religious doctrine, so they were willing to be flexible. The Romans could shift from Jupiter as a philandering husband who would turn his girlfriends into animals or trees to hide them from his wife, to Jupiter as an icon of perfect justice, without missing a beat. Christians and Muslims have resisted saying that Jehovah and Allah are just two names for the same God because they both have very detailed, specific ideas about their Gods that are incompatible, and neither is willing to just toss them out. 5. For any religion, there are going to be people who are very serious about it, who build their lives around this religion, and there are going to be people who don't care much, who will check the box for this religion on a form because that's what their parents were or that's what most people in their community are. If someone is nominally a member of religion X but barely knows what this religion teaches, goes to whatever worship services they have on major holidays once or twice a year, etc, it seems plausible that he could be easily converted to be a nominal member of religion Y. Especially if there is some benefit to converting, ranging from "if you want to get one of these high-paying government jobs, you have to convert" to "if you want to avoid being tortured and killed". [Answer] That depends entirely on what you understand under conversion: * Paper conversion: If conversion means that the converted speaks some creed, becomes a member of some religious organization, and takes part at their rituals, you can do this pretty much within a single year. Just go round to everyone, and force them to either accept your conditions, or face the consequences. True, you might have a few subjects less after that, but the others are all "converted". * True conversion: If conversion means changing their inner allegiance, you cannot do this within the lifetime of a human being. No matter how much force you use, the people who are really devoted to their own religion won't change their hearts and minds. You may force paper conversion on them, but you can bet that a good part of their traditional religion stays around. Given a strict "education" (= brainwashing every child within state-organized, obligatory schools), you can hope to somewhat eliminate the old religions over the course of a single generation, but definitely no quicker. --- There is only one loophole to this: If you can somehow "prove" that your religion is a super-set of their old religions, that they can continue pretty much in their ways as long as they also honor your gods, you can make conversion sufficiently easy to allow for true conversion to happen within ten years. This works really well if your religions are compatible, sharing the basic concepts, and not ruling out any of the fundamental concepts of the other religion. However, if there are any fundamental discrepancies between the religions, this may not work at all. This is pretty much what the romans did: You were free to worship your local gods, as long as you also accepted and worshiped the roman emperor as a god. This worked quite nicely for most other religions of the time, except for those stubborn jews and christians who would not accept any god beside their own. You see, the jewish/christian claim that there is only one true god stood in fundamental opposition to the roman polytheism, and it stopped those jews/christians from accepting the roman emperor as their god. They would even turn down paper conversion, and choose to be executed instead. The romans entirely failed with converting those. [Answer] Likely not. For the atheists of the today, religion is (simplified) some extraordinary ritual and the reading of gibberish books. For most religious people today, the religion is (simplified) the knowledge of the ancients and also a phylosophical viewpoint. In a medieval era, * science doesn't exist. Note the difference: it doesn't mean that there is a science but it is too primitive. The terminology didn't exist. Religion fills its role. * moral doesn't exist, religious laws fills its role. Of course everybody knew, for example, that killing somebody is a very bad deed, but how is it bad and why is it bad, there were religious answers. * a basic knowledge of the world doesn't exist, religion fills its role. Planets, stars, sky, earth, thunder were all religious terminologies with religious explanation. * the religion was also the state-organising ideology. The reason of the power of the King wasn't like "this is the law" (as today), rather that "God gave him the power". Note, this is not a God of some ancient book, but a God who really does exist, and if he wish, can kill us all or make us happy forever. In the mind of the medieval people, the hierarchical structure of the society didn't end on the Earth. The hierarchy lasted until the heaven, until God, and the local power (king) was only the procurator in the visible world. The result is that in a medieval people were much more religious as the religious people of the today. They lived in a world, where God is not only a philosophical terminology, rather God, angels really do exist. The result is that changing a religion - really - is unlikely in a single generation. This was also a reason, why the Romans simply inserted the gods of the conquered people into their, politheism. It even happened with montheistic religions, despite that the same "injection" was impossible. Simply elevating the role of saints, holidays similar to the conquered people, made their conversion more likely. --- There is another significant difference. In a medieval world, although the criminal law can be hard (and not always codified), the practical power of the rulers is far from the today. Personal identification didn't exist. If somebody committed a crime (for example, committed partisan attack against the conquerors), he could have flee to a swampy or uninhibited region, or simply far away. If nobody knew him, he left unpunished. There were no photos. There were no taxes. There were (mainly) no census. --- There is a historical example. After the collapse of the (West-)Roman Empire, next to the social collapse, the Christianity conquered Europe. The Barbarian tribes, founded states with pagan religions, often these states were converted to the Christianity. A timeline, in the Hungarian history: * the [pagan Grand Prince](https://en.wikipedia.org/wiki/G%C3%A9za,_Grand_Prince_of_the_Hungarians) converted to the christianity roughly at A.D. 970-980. Although he baptised, he still followed also the ancient shamanistic religion. * [his son](https://en.wikipedia.org/wiki/Stephen_I_of_Hungary) were crowned to a king in 1001. He was the first Christian king of the country. * He also imported a foreigner ruling class (priests, knights and so on) to strengthen his power. * There were many blood, [uprisings](https://en.wikipedia.org/wiki/Kopp%C3%A1ny), burning the pagan scripts, killing anybody won't convert, and so on. * The [last major pagan uprising](https://en.wikipedia.org/wiki/Vata_pagan_uprising) happened in 1046. * The last out-of-society pagan groups died out roughly a century later. In this case, the conversion of the country lasted roughly 70 years long. It is a 3 generation switch. --- Another very important thing: a religion shift means a social shift, too. For example, a chaotical warlord-based state should be reorganized as a Christian kingdom. Don't focus exclusively on the religion, focus to the social processes happening with it (and by it) concurrently. Thus, not only a religion change happens, rather * Society, government reorganization (in the example: free fighters of the pagan state were lowered down to peasants in the christian kingdom) * Power changes. In the era it wasn't common to lose power and survive it. In the example, a priest/knight class was imported by the Christian king to help to kill win his local opponents (note, he was also a traitor in the eye of the pagans, by calling foreigners against his own people). * Technological changes (f.e. pagans have bows and arrows, it is unusuable against the plate mails of the christian knights, castles were built) * And, the religion shift happens with these all concurrently, it is not alone. [Answer] Here's an interesting element you could try out that might make the 10 year goal more feasible. I think one reason why Christianity spread so quickly in the first century was because a major supernatural event happened which changed the world forever (of course, in the perspective of the new Christians) - that event being the recent death and resurrection of Jesus of which the apostles were first-hand witnesses. It was also seen as the fulfillment of many prophecies. In your world, there could be a major event caused by the god(s) (or at least attributed to the god(s)) in recent history that makes the religion seem more credible and urgent. If people think the religion's gods are real and powerful and active, they'll be more likely to convert, I imagine. And I don't know, maybe throw in some prophecies for good measure. Everybody likes a good prophecy :). ]
[Question] [ Vampires in my modern-day urban fantasy setting, to varying degrees, have a weakness to both sunlight and open water. The celestial energies Earth radiates out from its core take on different properties depending on what non-gaseous material they last passed through. If it was more than three feet of liquid water followed by less than three feet of any other non-gaseous matter, it will be as if a vampire were standing in direct sunlight. And depending on the strength of the vampire in question, exposure to sunlight or open water alone ranges from debilitating to dangerous, and both simultaneously is outright lethal to all but the most powerful vampires on earth. These rules, you may notice, still leave a vampire vulnerable to underground sources of water, as long as the water is deep enough and the ground between them and the water is thin enough. Which leaves open the interesting possibility that vampires' enemies might take advantage of this to take recently-turned vampires by surprise and trick them into walking into an area they don't realize qualifies as "open water". But of course, doing something like digging a moat and putting a tarp over it or things of that like would be fairly obvious. What I'm interested in is what sorts of pre-existing parts of modern-day life are already dangerous to vampires, and could likely catch a vampire off-guard even when they know they're supposed to steer clear of open water. What location in a modern-day society would a new vampire be most likely to not realize qualifies as standing over open water? [Answer] Water heater check it out... [![house](https://i.stack.imgur.com/tVUW2.jpg)](https://i.stack.imgur.com/tVUW2.jpg) [source](https://www.thermtrol.com/products/applications) Sucko the New Vampire is reading War and Peace on the potty, as is his wont. Little does he know that directly below and separated by only 6 inches of pressboard and linoleum is the 5 foot tall water heater. When the first rays of the rising sun peep through the bathroom window Sucko will learn the hard way! [Answer] # Travel: How many bridges are more than three feet thick? Parts of them are much thinner, but the bridge seems very substantial. Driving over a bridge with a fairly modest river beneath is lethal. This is especially significant to lift bridges, where the road bed is an open lattice of metal grate over water. That train trellis looks solid, but there is almost nothing at the center of each frame. Better not get on a plane - there might be less between you and that river 30,000 feet below than you think. That drain pipe has never been an issue before, but flooding means the thing now has three feet of water at the center. Ouch! Normally safe bridges can become deadly in the spring with increased water flow. Even walking over the wrong manhole cover could come to bite you. # Capped wells: Crawling around in an old basement sounds safe, but 20 years ago they capped a well with six inches of concrete. It looks like the floor, but with a deadly surprise. # Pipes: Pipes are thin, and old buildings may have plumbing going up in places you don't expect. Suddenly, a half-inch diameter pipe going straight up 20 feet swerves in the floor beneath you. You lean over the sink, perhaps, and the pipes come straight up beneath. Not to mention that clogged drain that normally goes straight down 10 feet, but now is backed up with a five foot column of water. Even standing in a room directly over someone taking a shower could be hazardous. The shower pipe fills, or even a five-foot stream of water pouring right down at the wrong moment... # Flooded basements: A frozen pipe in the winter starts filling the basement with water. With a clogged floor drain, it fills the basement higher - higher - a bit more. # Cisterns: My grandparents had a big, usually empty water tank filling up the room beneath their front porch. Fill it with 35 inches of water. Then, after a vampire walks through, add a couple inches. I swear I just walked through there... [Answer] ## Septic Tank These are often very shallowly buried in people's back yards, so they're not visible from the surface, but if you know where they are, you can trick a vampire into standing on top of one without knowing. They easily may contain over 3' of water (and sewage and other gross stuff). This water eventually seeps into the ground water, but you can fill it up quickly by turning on all the showers and sinks and flushing the toilets a bunch. For a more urban alternative, there's also: ## Storm Drains This obviously depends on it having rained recently, but many people in cities walk over storm drains all the time without even realizing it. Sometimes it's just a cut underneath the curb, and the water fills up a basin underneath the sidewalk. If you're walking on the sidewalk, you wouldn't even see the curb cut from that angle, as it's only visible from the street. [Answer] Crossing open water is a reference to the collapsing of liminality. In the case of rivers, the river is a liminal space (specifically I'm thinking of Gaelic superstition, although we do not have vampires as such), and to some traditions vampires have more power when they are in a liminal space like crossroads, traditionally, because they are also liminal beings (so, crossing them symbolically collapses their ambiguous not-dead-but-not-alive contradiction). So what other forms of liminality are there in urban environments? Bus stations, for one, airports and hotels, intersections... Depending on your take vampires might have more power in these areas but getting to their "other side" also forces them into one side of "is this thing dead or alive?". To your question, I'm not sure if water heaters are a liminal space, but sewers certainly are. Tricking vampires into climbing through a service opening or getting to a sluice could work if you wanted specific water-based trickery. [Answer] Few vampires realize (and those that do, the realization will last only a few seconds before bursting into flames) that it is not just crossing over the water, but anywhere close to the water, perpendicular to the gravitational gradient - i.e. crossing under open water counts as well. Having realized this, your vampire slayer takes a group to an iconic walk through the Vale of Llangollen in Wales. [Passing under the bridge that happens to carry the Llangollen Canal](https://en.wikipedia.org/wiki/Pontcysyllte_Aqueduct) over the valley. Of course, this assumes the vampires are not familiar with the local geography. [![Llangollen Canal](https://i.stack.imgur.com/mgRgn.png)](https://i.stack.imgur.com/mgRgn.png) [Image courtesy of Wikipedia](https://commons.wikimedia.org/wiki/File:WalesC0047.jpg). Note the ship sailing above. [Answer] # Sewers and Canals Did you know, that the sewers and rain drainage canals under a large town are more than 10 feet in diameter? In heavy rain, a 10 feet pipe can fill up to the 8 feet mark without problems as these tunnels guzzle the rainwater and try to get it to the rivers. They lie under the roads and pass through all areas of town. In many areas, the rainwater drain tops out at less than 3 feet underground with its crest The enterprising vampire hunter uses this knowledge and goes to stalk their prey when it rains heavily and knows at which places the pipes are clogged enough to fill to a point that the 3 feet of flowing water are reached. They then hunt the vampires into the junction of such channels. If they are particularly nasty, they could even deliberately channel river water into the rainwater drains or use shutters to flood certain areas of the tunnels. The flooding of those canals will easily lay traps. However, rainwater is even more effective: it comes from the clouds which have been exposed to sunlight just over the horizon - or already are in the sun, making the canals even more deathtraps. Note that under the rules presented, just lazily trickling any river water into the tunnels of both sewer and rain drainage during the daytime will kill all vampires hiding in or under them just as surely as it will eradicate vampires hiding in auxiliary constructions to the sewage systems. [Answer] In the Low Countries, many expat vampires get killed when they try to cross a pond or canal covered with Lemna (Eendenkroos) because it looks so much like grass. Have a look at: <https://en.wikipedia.org/wiki/Lemna> and ]
[Question] [ Would it make sense for animalistic shifters to have mounts when they can shift into a large feral-like form? That is, not humans that turn into animals, but a species of large humanoids that can turn into a more feral beast-like form while maintaining sapience. Would it be easier to just shift into the secondary form to pull things or carry things or whtever or would it be better to have an actual mount (like a horse or camel)? [Answer] Ricardo's Law of Comparative Advantage. It doesn't even matter whether the draft animals are as effective as the shifters. All the matters is that having the draft animals pull the carts allows the shifters to do other stuff, so as to cover the cost of having the animals do it, and some on top. (Net: profit.) Suppose you had five blacksmith shifters. Every year, they have five carts full of goods to sell at the annual fair. If only one of them actually has to make the week-long trek, sell the goods over the two weeks of the fair, and make the trek back, the four remaining can spend that month making more goods. Also, if you ride a mount to, say, a court of law, you will arrive less tired and so better suited to argue, and your mount, if it can eat grass when you can't, means you need less food. [Answer] They would have different mounts for the same reason have different types of vehicles. But your creatures can just shift into a stronger and faster form,why would they use mounts? Because they are lazy and because vehicles/mounts allow good combinations in various niches like in construction building or in the military for example. [Answer] Humans can walk and run very long distances and very efficiently. Yet we’ve still bred mounts for thousands of years. We are also not that weak compared to a wild horse or cow. The advantage with mounts is that you can let the mount do most of the work while still arriving relatively fresh and with more luggage than you could carry on your own. You can also use several at the same time. They’ve also been used as currency, fresh food and status symbol. [Answer] The correct answer is: it depends. ^^ If these shifters try to live hidden between humans or there are other reasons not to use their shifted form too often they would be in need of a mount as often as normal humans are. If they form a society on their own the situation is totally different. Their abilities would cancel out most of the advantages a beast of burden presented to human society (higher speed, ability to move high amounts of material fast and long distances and so on) so I think they would use them less then humans did in history. They woudn't be useless whatsoever as they still mean a source of transporting MORE material, travel long distances without fatigue an such. [Answer] "Your job is to be a plough-horse 12 hours a day. Or a cart-horse. Or a mill horse." "What?? Can't we get equines to do that?" "Well if you're going to be lazy...." Any intelligent species is always going to find alternative approaches to spending long hours of backbreaking toil when they could be doing something more productive. Domestic animals have always been a useful alternative to doing it yourself. In the modern era, people who are quite capable of walking a mile or two often prefer to take alternative transport if it's available. [Answer] My take would start by taking in account human is the most economic traveller by foot in nature. So I'd assume the feral form would be less so and their humanoid form more like humans. Therefore in some cases where you need to keep the feral form for long periods of time a mount would be better to move around. The other obvious reason is war. They could charge in horses then switch to feral and strike with the added momentum and potential from height. [Economy and Endurance in Human Evolution](https://www.sciencedirect.com/science/article/pii/S0960982217305675) [Answer] How fast and/or strong is your secondary form? What other factors need to be considered? If your secondary form is, for example, a wolf, then your shifted form has a top speed of about 37mph. A horse, on the other hand, has a top speed of about 55mph. When sheer speed was required, mounting a horse would be a better choice. Suppose you need to carry heavy items over a long distance (possibly including fording a river). Wouldn't it be easier to ride an elephant, instead of having to either make multiple trips, or get other people to join you? Finally - let's assume you were trying to cross a desert. In humanoid or wolf form, your feet sink into the sand, and the exercise dehydrates you rapidly. On the other hand, a camel has wide feet (so as not to sink into the sand), is adapted to long periods without needing to drink water, and carries its own supply of energy (fat stored in the hump) - again, mounting the camel is a better choice [Answer] Your species has two forms -- humanoid, and what you call feral. You don't describe it, but imagine for the sake of argument that it's akin to a bear. Now imagine all the types of animals humans use as mounts and haulers -- horses, mules, donkeys, camels, elephants, oxen, yaks, llamas, alpacas, dogs, goats, other humans, etc. While some are the choices of poverty or unavailability of better choices, most of them have a niche where they are superior. So, there are probably situations where a human is best off walking, situations where they are best off switching to feral form, but in the majority of situations it's best to find a suitable mount. I don't think having an animal-like form will turn people into strident vegans. ]
[Question] [ In a fantasy world I've been working on Dragons are venerated by many for their ability to seemingly summon rain where ever they roam. It's common for the peasantry of the south to leave offerings of both animals and incense to not only attract dragons to a region, but also as thanks for the blessing of rain. What kind of gas or chemical would a Dragon have to exhale to cause rain? The effect doesn't have up be spontaneous, but anything quick (a few hours) would be preferable. Note: don't worry about how a dragon produces the chemical too much. That will be the topic of another question. [Answer] Salt. Also, ice. But not the normal kind. Cloud seeding is a pretty cool technique, and involves blasting ions into clouds to make them rain. Normal salt (sodium chloride) is effective, but there are a few others which make for more effective draconic breath weapons, like calcium chloride (eye irritant), silver iodide (also an eye irritant) or solid carbon dioxide aka dry ice (can cause frostbite on contact). [Answer] [Frame Challenge](https://worldbuilding.meta.stackexchange.com/questions/7097/a-proposal-for-helping-users-understand-frame-challenges): It's irrelevant what they breathe If the dragon was the size of a Boeing 747, the exhaled breath wouldn't be enough to cause more than a second worth of rain over a 500-population town. If the only thing the dragon exhaled was pure [silver iodide or CO2](https://en.wikipedia.org/wiki/Cloud_seeding) it wouldn't be a large enough quantity to cause substantial [virga](https://en.wikipedia.org/wiki/Virga). If you ignore that inconvenient truth, then I'd vote that your traditional money-grubbing dragon, having slept so long on a huge pile of precious metals located in an undersea cave with surface access (iodine can be derived naturally from brine), spews silver iodide. [Answer] Pollens Some time ago, someone told me that Sugarcane farms cause rain, I am not sure if it is just some kind of belief or an actual fact. But if we assume that sugarcane generates some kind of pollens (again, not sure if they actually do) that when comes in contact with clouds may cause [cloud seeding](https://en.wikipedia.org/wiki/Cloud_seeding) and hence causes rain. You can use something like this. Lets say that your Dragons like to spend a lot of their play time in grasslands that cause a lot of pollen to get stuck into their body scales and a lot more to go inside their respiratory system (also assume that it doesn't cause the dragons to sneeze a lot, like the way it does to me) and when these dragons go high up to the cloud altitude the pollens comes out and acts as cloud seed. You can also add a twist to it, by assuming that these pollens have some kind of bacteria that flourishes inside of your dragon's respiratory system and produces some micro mucus particles that also adds up to the required quantity of cloud seeding. [Answer] Dragons are reversed heat engines, similar to refrigerators and air conditioners: they breate out hot air to cool down their bodies. This causes moisture in the air to condense around them and fall down in the form of rain and snow. [Answer] Dust. Rain droplets originate with a bit of dust that the water droplets collect and condense upon, until it gets too heavy and falls. Exhaling (or otherwise excreting) lots of ash would be a good choice and appropriate to dragons. <http://volcano.oregonstate.edu/how-do-volcanoes-affect-atmosphere-and-climate>: > > The main effect on weather right near a volcano is that there is often a lot of rain, lightning, and thunder during an eruption. This is because all the ash particles that are thrown up into the atmosphere are good at attracting/collecting water droplets. > > > [Answer] They could exhale then burn hydrogen gas for their flame breath - the direct result of burning hydrogen is water Not familiar with biological processes that generate hydrogen (I imagine it would be very energy-intensive) but regardless, it can also help keep them aloft by storing the hydrogen in gas-filled lung-like sacs between their internal organs [Answer] Soot can also act as a cloud condensation nuclei (worse than what others mentioned, but you probably don't need 100% reliable rain generating dragons), so one way would be for the dragons to exhale flames with the incomplete combustion of something producing lots of soot. Interestingly, propane itself is a cloud seed so if your dragons run on propane they could exhale this combination of seeds :) They might also shed skin/scales while flying in large quantities which have high concentration of non-organic seeds others mentioned. I know you said you didn't care, but one reason might be that they need/enjoy lightning and have evolved to increase the probability that thunderclouds will form around them. [Answer] Just a thought: do you allow semi-magic? If a dragon can belch out a large thermonuclear device, that explosion will definitely produce rain. You did say "don't worry about how a dragon produces chemicals..." but unless you're going to present dragons as having supernatural-chemical-lab powers, that isn't going to happen either. [Answer] To stray slightly from your specifics - what about non-chemical rain seeding? Such as a sonic-boom type "bark", or perhaps lightening based? ]
[Question] [ I have a sentient lifeform populating an Earth-like planet in terms of gravity / composition. But since that world is close to an old K Type star, the atmosphere is evaporating and letting UV rays reaching the surface & making it pretty hostile. Life had to go underground for surviving and evolving. In my scenario we have arthropods who attained sentience and the ability to manipulate tools by using their four (4) pincers. Living in the ground with no light has made them blind, they can perceive their surroundings by using ultrasounds (like our bats), and a powerful capacity to smell minerals and all types of molecules. How in that context, the life here could reach space? [Answer] I don't see how they could go straight from underground to space. They would first have to (at least partially) re-conquer the surface. Using the surface could be very interesting for them, as transport is much cheaper. Of course you need protection there, so a first milestone could be some sort of automated surface train. This could be connecting underground areas that are hard to connect underground (difficult geology) or to increase throughput (maybe to transport ore and coal for their industrial revolution) between already-connected destinations without the need for expensive tunnels. The next milestone would be atmospheric flight. I guess even discovering jumping and gliding could be pretty hard for blind tunnel-dwellers. (As @Tomeamis points out, that is already possible in natural or artificial caverns. Still might be counterintuitive for a crawler.) However, as a sentient species making scientific discoveries, they are bound to find out about it eventually. Flight has the same incentive as for us: Faster transport without as much fixed infrastructure such as rails for trains. They are going to need technical help such as radar to develop flight, since sonar is not accurate enough to fly with precision. Or maybe one can make it accurate enough if one is born with sonar senses, who knows. Either way, flying will be too risky with only their natural senses. Big question: Can you make planes light enough while still being protected against radiation? Relates to the density of the atmosphere. The last step is space. When they master atmospheric flight, they will know about gravity, the shape of the planet and the decreasing density of the atmosphere as you go up, so the concept of space would be within their grasp. But why would they go to space? Could they use satellites or is the radiation to high? Would they want to militarize space? All in all, I would say you could paint a realistic-enough picture, but you definitely need the stepping stones of surface transport and atmospheric flight. [Answer] > > they can perceive their surroundings by using ultrasounds (like our bats), and a powerful capacity to smell minerals and all types of molecules. > > > None of those abilities will make them aware that there is something called "space" above their heads. What is current space science started when some humans started looking up in the sky and noticed the stars, and noticed that some of them were behaving oddly. From that observation came all the theories on cosmology and from there it sprouted space exploration and space science. Ultrasounds and smell do not help in noticing the sky. They will be blissfully ignorant on anything related to that. [Answer] I'm assuming they've got access to their recorded history and know about the time when they were on the surface, or have noticed something unusual (eg gravity waves) and want to go check them out. Basically they know space is there and want to go there. I see a few paths: * *They find the Star Gate* or a buried crashed alien ship, or some other peice of advanced alien tech which either transports them directly, or they can reverse engineer to build a ship. * *They just use FTL underground. Whether that has effects or not is up to your imagination, FTL in the middle of a massive underground chamber sounds loosely plausible. *Surface mounted big doors. Build pressure suits. Use pressure suits to do work on the surface. Build a big honking space door. Build a big ship underneath it in an airtight chamber. Open outer doors. Fly into space. Close outer doors. Best used at night to minimise radiation. *Really long underground railgun poking out the surface* If they're very good at building big underground structures, they can build [StarTram](https://en.wikipedia.org/wiki/StarTram), which is basically a long maglev rail launching something into space or landing it. Since your atmosphere is gone, you can get a vacuum for free inside a tube sticking out of the surface, giving no air resistance during launch. [Answer] Because it’s there This may be a bit of a cop out, but just because biology dictates they be subterranean doesn’t mean they can’t be curious about other environments. Humans aren’t made for living deep underwater, and yet there are sub nautical observatories. If these creatures view things via echolocation they have a concept of far distance and such. They could use technology to explore the surface, most likely using some form of sonar pings to expand their own echolocation and environment suits. From there a good way of them discovering space would just be them expanding their sonar to map more and more of the surface. And then one day they get a ping off a moon or asteroid or something. Suddenly there’s a massive “Oh DANG, there’s STUFF in the great nothing above!” Humans have been aware of space because we can look up and see all those things, but modern scientists bounce various waves and signals off celestial bodies all the time. After that initial realization it would be a natural progression for curious scientists to simply start angling their sensors upwards and seeing what gets bounced back. And then building things to get closer and send even more information back. [Answer] Like others I assume the answer is "yes", and I think Jann Poppinga's answer is very good. But I also think the issue of them being blind is a very interesting one and L.Dutch makes a good point that it's hard to see how they discover any cosmology at all without sight. And while I don't think that would prevent them from flying higher and higher, noticing the atmosphere thinning and disappearing and being curious about going further and further, and figuring out ballistic properties through trial and error, it's still hard to see how and why they'd go further into space beyond a certain point without the notion of other spatial bodies and the ability to know where they are. It's not like they'd just stumble into a neighbouring planet, the distances are ridiculous. But of course there is no reason they won't be able to sense light, blind as they are: we use technology to sense all kinds of physical entities we cannot sense with our bodies. So what I'm finding interesting is, how would they discover light, what would it seem like to them, what would they do with it? First, I think at the very latest they will discover light around when they've discovered electricity and developed a theory of electromagnetism, as we discovered radio waves. Actually in your scenario I think that even if the sentient lifeforms in question are blind there would be a sighted biosphere in existence because you only described the surface as having a lot of UV... living things could adapt to that, maybe not a thriving biosphere but some organisms that could be worth sneaking out of the caves to eat (you also don't mention what your biosphere would be based on, energetically speaking. It's quite possible it wouldn't be possible for a biosphere to sustain sentience without using light energy in which case your sighted biosphere would be very significant indeed). It would also be pretty safe to exist around cave openings where it would be easy to avoid direct exposure to UVs, and those would be lit environments where sight would be adaptive. As such, these blind organisms might have become aware much earlier through the science of biology that some organisms have an uncanny ability to hone in on prey, and that this is related to these "eye" organs they have. Once you have that, and you have electromagnetism, you have both the incentive and information necessary to invent a visible-light camera, and once you've done that you can discover that wait, your camera is picking stuff up in that emptiness above the surface????????? (I don't know if you could use the principle of the phone to connect up a light receptor to an ultrasound emitter to allow for some approximation of "direct" light perception, at which point you would just need to adjust either end to get as useful information as you can). On the other hand we could modify your scenario a bit to have true blindness - the sun's rays are fatal in very short order to all but extremophile micro-organisms, and the biosphere runs happily on some very high-yield chemosynthesis. In this situation maybe it would take until the discovery of electricity before our arthropods had any notion of light at all (though there is always infrared, you don't really form pictures or see stars with it), and I'm curious if they ever would figure out image-forming cameras. Electromagnetic waves would be certainly useful to them for communication, especially once they colonized the surface. They'd also likely use them for sensing the world, as we use radar. They'd already know about the day/night cycle at the surface just from temperature but they'd see a corresponding pattern in other electromagnetic waves. They could figure out the waves have a point source just from shading effects, and that's a discovery of the Sun and at that point they can have a notion of space, as in "stuff happening way beyond the surface of the planet". With more focused and sensitive detectors I suppose you could find stars (even better if there are moons and certainly planets) and then you're off to the races, astronomy-wise. [Answer] If they have expansionist tendencies, their exploration and exploitation of the surface and eventually space is functionally inevitable (assuming they don't go extinct before hand). The only known sophonts are humans, who have demonstrated a tendency to and flair for expanding into available space, even ostensibly inhospitable ones. What we don't know for sure is the source of that tendency; it could be cultural, but the latest batch of imperialist expansion wasn't the first, just the most comprehensive. If it's physiological, onmivorism may have played a part, or bipedalism, or visual orientation. It might be a fundamental aspect of all intelligent life, or even just life in general. We don't have the data to know. Decide all intelligent life is expansionist and you're sorted. You can spike the protest by having someone ask how your species realized there was a sky, and having an individual incredulously ask "How could we not?" or otherwise dismiss the question as naïve. If you want a specific path towards the realization, just have your species encounter radioactive isotopes. They won't be able to smell anything but alpha radiation if even that, but it will rapidly become apparent that something is going on when individuals start dying of acute radiation poisoning even when they're protected from the killer helium. The discovery of any portion of the EM band will eventually lead to the rest of it (they'll just wonder what's going on around and between 380 and 700 nanometers), which will help with a whole bunch of fundamental physics that should inevitably lead to the big questions. [Answer] Like L.Dutch - Reinstate Monica, I don't see a good reason for this population/civilization to get into space. It's not the tech that's necessarily the problem, but psychology is a huge factor when the people can't perceive something. And perception is a huge factor when trying to comprehend something. It would have to take some very special circumstances to align just right to let this happen. For instance, in the communication or other electrical gear they invent, they may notice interference. This could be interference from the nearby star, but because they can't see it, they would attribute it to something they do understand and can comprehend, the core of the plant. It would have to take a special kind of thinker to consider putting some kind of direction finder to figure out where the interference is coming from. Most engineers would likely just work to shield or otherwise remove/negate the interference. It would take some really severe interference for more than just a single person to look for the source. If they realize there's likely no way they can do anything to prevent the interference, they won't do anything about finding the source. And even if they do find that the interference is "up", they probably still have a taboo about going to the surface, due to the circumstances you describe about how they became cave dwellers to begin with. Even if the thing they discover is deadly radiation, that just plays into the taboo and they are more likely to dig deeper to get away from the radiation, rather than go towards it. Since their ancestors chose to "run away" from the dangers of the surface, instead of invent technology to deal with it, they likely have a civilization based around this fear. It doesn't even matter if the ancestors had the resources to invent the tech, they still chose to dig down. With any civilization, there's a lot of pressure to "continue to do as the ancestors did". This is how "well we've always done it that way" comes to be as a saying, among more dangerous doctrines, but I won't get into that. With this taboo, even if the original thinker figured out that the interference/radiation is gradually reduced then disappears completely in an area, then realizes there's nothing causing this below, so it has to be above (a lake or ocean), it would still take quite a bit to convince the people in charge to figure this out. Then again, they may already be living there and know about the phenomenon without caring why it happens, and literally no one in generations has thought to ask why. It may have even worked into the taboo no to ask that type of question. And with strong enough taboos, they can work into laws. It may even be against the law to go to the surface. Maybe all this works into the story, where the original thinker decides to go off on their own to discover "up". They would likely have to work on their own for quite a while, until they secretly convince others to join the venture. It might even become a haven for the "unclean" (or whatever) who make a nuisance of themselves by breaking the taboos/laws about "up". This is still a tenuous story line, but I've enjoyed even more unrealistic plotlines, as long as it can hook people by their emotions and/or curiosity. :-) [Answer] ## It's actually easier without an Atmosphere If you strip away most of the atmosphere, it's probably easier for an intelligent species to become space-faring. All the complexities of space travel stem from the tyranny of the rocket: more weight means more fuel, but more fuel adds more weight! With a non-existent or very rarefied atmosphere, an intelligent species could use mass drivers to get to space. A mass driver is basically a railgun cross bred with a bullet train: a long track - say 200 miles - that accelerates the ship to orbital velocities. Then you use a small rocket burn to circularize the ship's orbit. This moves the fuel source off the rocket, thus allowing much higher launch weights. Mass drivers don't work on Earth, because traveling through the atmosphere at orbital velocities causes the ship to melt / explode / disassemble. ## But would they discover Space at all? Of course. We use RADAR and X-Ray technology to for a lot of our space research. Neither of these technologies return information in formats that humans can understand natively. We use intervening technologies - visualization software and computer displays - to convert the data into something we can understand. Likewise, a society that "sees" the world through sonar will develop technologies to interpret X-Ray, RADAR, and even visible light information into some format that they can understand. When this society reaches the surface world, they will naturally use these existing technologies to understand it, and will therefore invent astronomy. [Answer] I like Jann Poppinga's answer, but would like to extend it a bit to respond to the quite valid concerns of "if they can't see the stars, why would they think there's something up there?". That was my first thought too. ## Give them a moon to shoot for While their star (which creates times of different warmth, even if illumination is not noticed) might qualify, giving them a moon (especially a big one like ours) would help a lot. Once they're using the surface for transportation (by land or air), noticing that at different times - and quite regularly periodical ones - the temperature at the surface is different would only be natural. But there's several ways to explain that - and the "there's more land to conquer/settle in the sky!" theory would have to compete with the "there's a huge ball of fire circling the world" one. A large moon with easily noticeable tidal effects (even without large bodies of water this would be rather measurable) would give them a notion of "other hard bodies are out there above us", and a target to shoot for. ## Light sensors (infrared first) Of course even without a moon, measuring light with sensors would be a natural development too. The visible (to us) spectrum of light is only a small part of the electromagnetic spectrum - and infrared radiation (aka, "why can I notice that a rock is warm from a distance?") is very close to visible light. Sufficiently advanced measuring equipment aimed at infrared wavelength might even be able to pick up the planets and stars from the ground - giving them the motivational breakthrough they need. [Answer] There's no reason why they can't. All they have to do is mine a hole to the surface, and use that to launch rockets. There's no reason why they would have to build a civilization on the surface, just like humans didn't have to build underwater or underground civilizations to send rockets to space. ]
[Question] [ There is a lord who is being kept prisoner in a castle tower by a griffin who has taken over his home, but requires the lord be kept alive for political value. Naturally this requires the griffin giving him food and water. Food should be simple, either feed him stuff already stored in the castle and/or once that runs out, give him leftovers of what the griffin eats (deer, sheep, goat etc). But what about water? The only way I've thought of is the griffin taking him out of the tower, flying him to the nearest river or stream, have him drink from there and then take back him to the tower but that doesn't like a good idea. Can you help me? Edit: Wow, I didn't expect this question to gain such traction. Thanks folks :) [Answer] In medieval times, this was given quite a lot of thought as castles were designed in most cases to [survive a siege](https://www.ancient.eu/article/1230/siege-warfare-in-medieval-europe/). Food is an issue during a siege to be sure, but water more so; this ties into the law of 3s; you can survive 3 minutes without oxygen, 3 days without water and 3 weeks without food. These are of course approximations, but you get the general idea. Water was always going to be the biggest problem in a siege as humans (and stock) need to drink so much of it and don't live well without it. Also, it wasn't uncommon for the wells outside a castle to be poisoned in times of conflict; there was often minimal security on the outside of the castle wall by comparison to inside so wells were often targeted as a weak point in a castle's supply chain. How do you fix this? You dig a [castle well](https://en.wikipedia.org/wiki/Castle_well). Most castles had one of these, and many of them had to be dug very deep thanks to the fact that the castle was often built on top of a defensible hill. The point being, that your castle most likely has a well and so long as you give your king access to it you're all set. But (I hear you say), isn't that a risk? Can't the king escape that way? Well, no. He could commit suicide by jumping down the well head first if he had a good reason to do so but wells are not vertical tunnels to a cave system; they generally just go down deep enough that the groundwater levels are now above the lowest part of the well, which then means that the bottom of the well fills up with water from the groundwater supply. Ideally, you'd have servants fetch the water to the room in which he is incarcerated, but depending on how malevolent your gryphon is, making the king walk down the tower stairs, draw his own water and carry it back to his room each day might be a fitting insult to rub salt into the wounds of the king as well. Either way, the point is that your king is unlikely to have to leave the castle in order to get to a water supply, which is good news for your gryphon in terms of security, but bad news for the king if he's out of shape from sitting on a throne 10 hours a day for the past few years. [Answer] A number of options. The castle has a well within its walls so the lord can toss a bucket down and get water for himself. A more modern castle might have hand pumps in appropriate places so maybe no need for a bucket. Assuming the castle isn't in a very dry region, rain could be collected from the roof and fed directly to cisterns, from which the lord can get water. Alternately, the castle may be surrounded by an impassable moat (or have a small stream running through it) - the lord can drink from there. If there are no water sources in the confines of the castle, or if the griffin wants to keep the lord trapped in a water-less part of the castle then it could fly to a pond, immerse itself then fly back and let the lord lap water from its still dripping body. Worst case scenario - the lord has to survive by drinking the blood of some of the creatures killed by the griffin. [Answer] ## Ask tribute to the locals The lord not only controlled the castle, but also the whole region around it, and all the yokel that live there. The griffin does not only control the castle, but also (even if it's less than the lord), the region. He can probably ask to one of this folk to gather some water and deliver it to the lord. Same can be done for food, so he don't have to only eat raw meet. You don't even have to search them in the countryside if you didn't kill all the serveants/noble family in the process. [Answer] You do realize that he's probably going to need water for more than just drinking, yes? If the griffin wants to keep him alive, that means taking into account basic hygiene, and that needs water. [Answer] If his food contains enough water, he doesn't actually need to drink. Maybe the griffin brings him mostly fruits and vegetables. [Answer] The griffin has enough limbs to be able to carry a bucket to the nearest river or lake, fill it and fly back. If it's a big griffin maybe it can carry enough in one trip to provide a day or more water for the lord. The problem would be getting the water into the cell... You can have a hole in the door (or bars) big enough to get a meal through without too much trouble, but a hole in a door big enough to get a bucket through would allow a (desperate) lord to get through. So maybe posit a cell that has an open drain for bodily functions and every so often when the stench gets too much for it, the griffin just throws a barrel full of water in to the cell to wash the lord down and wash all the loose stuff down the open drain. It means your dungeon is above water table so the effluent can drain out rather than ponding over the cell floor and spilling back into the corridor. For drinking water, let the lord dip into a bucket outside the cell. If he's fussy he can rinse his hands with a cup of water sometimes when they get too crusted with noxious stuff [Answer] The Griffin can store water in its feathers, it flies to a nearby lake, immerses itself, then carefully flies back. The [Sandgrouse is a type of pigeon that purposefully carries water](https://www.audubon.org/news/why-would-bird-carry-water-its-feathers) in its feathers for its Chicks. The Chicks then 'milk' the carrier (either male or female) by sucking water from its feathers. [![enter image description here](https://i.stack.imgur.com/fib6J.jpg)](https://i.stack.imgur.com/fib6J.jpg) ^Image of a Sandgrouse gathering water The same could perhaps be done by the Griffin, with the King licking its feathers for water. Or, alternatively, the Griffin could 'shake' the water into a locked tub or bath, for which the King can then relax in or drink and still be securely imprisoned. [Answer] All you get is light and a large enough peace of soil + water & some seeds. If you dont grow food for air and food you will starve and die. If you eat your seeds - you will die. Its basically a miniature world to be robinson crusoe in.. ]
[Question] [ At the beginning of my worldbuilding, I thought it would be nice to bond nicknames for characters of either highlighted importance or supernatural power. This naturally appearing differentiation is a gloriously amazing way of character building in my view. So I came up with a bunch of possible outcomes - here's all I have so far, in categories: * simple English words: Red, Woe, Hammer, Jelly * direct descriptions of abilities: Iron Fist, Jumper, Visioner, Immortal, Pinfinger, Siphon, Carrier * personalizations: Drifter, Amazon, Iron Maiden, Iron Fist, Hackerboy, Energizer, Paladin * animal names: Medusa * mythological names: Kebechet * words of non-English origin: Diablo * other means of differentiation: Boss, Second, Ladykiller, Reaper All these categories are very limited and can easily get 'filled' to the point of additional namings would not make any sense. The problem is that initially, I invented these nicknames for the law enforcement body of my world's dominant power, in order to keep track of all the potentially threatening individuals. The reasoning behind this is the nicknames are either naturally coming (Drifter, Kebechet) or are distinctive enough to be easy to apply. (Red - for hair color, Woe - for personality) Even after some decrease in the size of my world, the local population is much too big to be suitable for such a simple naming system. You can easily imagine a random person claiming e.g. the nickname "Drifter", for him-/herself or his/her band, organization or even race. This would lead to extreme confusion at some areas, especially if names can be 'reclaimed', for example, if the original Drifter is caught and/or killed. How can I guarantee that such simple names can stay unique even when others attempt to steal them? [Answer] ## Combine nicknames to get millions of possible nicknames The OP is correct that singular nicknames is problematic because there just aren't enough names to go around. A possible solution to this is to generate names like "LHJKNJOO" or "KJHJHUIUXZMC" to identify someone with the obvious trade-off that those names are basically unusable for identifying anyone. Yes, those names are technically unique but no human read will want to keep track of those names. They'll probably just close the book. ## However, Baby-faced James isn't the same as Baby-faced Willy If the author combines a set of adjectives along with a set of nicknames, the potential combinatoric name possibilities grows very quickly. Say you have 100 adjectives and 100 nicknames. All possible combinations will be 10 000 different names. Even if you go with choosing just 2 names out of 100 possible names, that will give you [4950](https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=100%20choose%202) different combinations. Choosing 3 of that 100 gives you [166167000](https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=1000%20choose%203). The Black Drifters are very different than the White Drifters. Likewise, Rob Anybody Feegle is clearly not the same as Never Rob Feegle. ## Better than Acronyms While three letter acronyms can offer equivalently sized name spaces, they lack the story telling power of the adjective+nickname approach. Consider the simple 'HJB'. The author will need to spend some amount of time building up a meaning for who HJB is and why that sequence of letters should mean anything at all. But "Hard Joints Bobby" instantly brings to mind a stiff legged person. In real life, nicknames are chosen as a shorthand description and identifier for people. Acronyms are almost never used this way. ## Alternatively, make up your own words Building names using sounds that appear in English but don't form actual English words would work too. For examples, look no further than your favorite brand-name pharmaceuticals. (Big-Pharma is actually very careful to choose brand names that don't mean anything to anyone in any language. You wouldn't want to choose a name that doesn't mean anything in British English but is a horrible slur in some dialect in Africa.) [Answer] You can't, but that doesn't matter Consider the nickname "Red". It's a real nickname, which has been given to thousands of people, real and fictional, generally for having red hair. However, it doesn't really matter that multiple people have it, since generally these will be people that don't really know each other and don't operate in the same circles. This generally works because people a nickname is only going to stick if the people around you want to call you that. If there's already a famous "Red", and you want to go by that nickname, nobody is going to care because "Red" already refers to someone else. They'll pick a different nickname for you, and you'll get to go by that name. This is true even if the nickname you go by is something that you picked with no knowledge of the other "Red", or if it was given to you in a different place of by a different group of people. Red will go on being Red, and the newcomer will get something like "Little Red," "Baby Red," or whatever else people want to call you. Over time, Baby Red might become a famous criminal in the area, in which case nobody else would go by or be referred to by the nickname "Baby Red". Everyone in his social circle knows who that is, so referring to someone else by that name would only cause confusion. Nicknames ultimately aren't unique identifiers, they're what everyone in the area (or even just in one social circle) calls you. If you social circle decides your nickname is confusing, they'll give you a new one. This applies for law enforcement, as well. Within a department, they'll probably come up with unique names for criminals, but different departments or different precincts may use the same name for different people, unless that individual is significant enough to be on the radar of both organizations. [Answer] Names are Contextual So I mention James. James who? That's a great question. 'James' doesn't denote a person in-and-of-itself. It's like saying "the dog." What dog? Now imagine how mentioning "the dog" in a room with just the two of us, and a canine companion. 'Oh, that dog.' So how about James? Well if you visit the World Building chatroom, Factory Floor, there's a good chance you'll know the great member of our Community James. If I bring up 'James' there you'll have a reasonable guess what James I'm talking about. So how does that apply to our criminals? If I mention Hammer on the island of Vandrin, everyone will naturally think of the local criminal Hammer; after all Hammer robbed the Greater Will Bank and was responsible for at least twelve murders on the West Bank. *To everyone who would care about Hammer knows which* Hammer you're talking about when you mention his name.** If you can't stand for names to be contextual and have to have them unique... well welcome to the early days of the Internet! Dial back the time machine a decade or two and you'll come across the evolution of forums and chatrooms. There, names had to be unique, but people's creativity with usernames hadn't... evolved to where it was today. Instead they went for a simple basis like "LadyKiller" and "JamesBond" and "HotChick." Of course, many, many other people thought of the same things, so these names became "L4dyKi113r" and "xX-JamesBond007-Xx" and "HotChick1987" as people were forced to insert variety into their names. Quite simply, there's only so many unique names that people could come up with that sounded cool. You'll run into the exact same issue, as you've seen. [Answer] ## Add the region/city of origin to their name What is the easiest way to refer to two different people with the same name? Just use their place of origin - e.g. James from New York and James from Munich. So just let every Police-Department add their local region/city name to the Name of the villain. Locally the Drifter can just be called the Drifter. But everywhere else on the world he will be called "London Drifter" and if a second Drifter appears somewhere else on the world that will be for example the Tokyo Drifter ;-) A few thousand cities times a few thousand names should be enough to cover your world of supers. Just like with normal names and family names, you can add the city part only, when clarification is needed. So as long as everyone only knows one Red Woo you can just call her Red Woo, but if you are not sure, you can ask "The Kentucky Red Woo?" - and they can specify "No, we are talking about the Hong Kong Red Woo" [Answer] You will get repeats, and that's okay. You can even play with the notion. Imagine a busy night at City Watch HQ: Captain: Sarge, who'd we arrest today? Sarge: Let's see... Big Ted, Little Ted. Jenny Psycho. Lefty. [Grins] And three guys named Lone Wolf. Captain: [Sighs] You put all three in the same cell, didn't you? Sarge: C'mon Cap, how could I not? I mean seriously. [Answer] Pretty much all things, including nicknames, have to have context. As long as they have a reason, people will keep them straight. But there's always a story behind them. Broad These are based on place or function. Since names are contextual that can work for coming up with unique things. Examples are: Cabbie (for cab driver, and you can call any driver that), Outlander (for someone not from around here) Based on Physical Attributes or particular skill Gangsters did this--things such as "Red" "Fat Lips Jones" "Freckles Malone." Literally anything "Knives" even. Based on what the person did, that one time Many nicknames are not welcome. So you scream that one time because of a spider--and every after, you'll be called "Screamer" or "Spider" because you have arachnophobia. [Answer] I'm going to address the problem of giving unique nicknames to lots of people while keeping those nicknames short, as it seems to happen on your world. Of course not all nicknamed people in the world are going to be individual characters in your novel, but the naming system needs to work even for the people not showing up in the novel. If you don't care about readability and meaning, a nickname is just a string of letters (like XKCDXKCD). If you use the English alphabet, you can get 26 one-letter nicknames and multiply than number by 26 every time you add a letter. This way you can get more than ten million nicknames with just 5 letters and more than a short trillion (10^12) with 9 letters. If you want something people can read an pronounce, the estimation gets a bit more difficult because there are different ways to arrange letters that can be pronounced. A rough estimate would use silabes formed by one consonant and a vowel (like in WOBUSE). In English, 105 of such silabes can be formed (21 consonants \* 5 vowels = 105 silabes). This way, you can get over 1 million nicknames with 3 silabes (6 letters) and a short trillion with 6 silabes (12 letters). If you want to use only meaningful English words, you will need very longer nicknames. According to [this paper](http://languagelog.ldc.upenn.edu/myl/Shannon1950.pdf) (as cited by [this xkcd-what if post](https://what-if.xkcd.com/34/)), English text contains about 1 and 1.2 bits of information per character. That means that to get one million different English texts you need about 20 characters, and to get a trillion different texts you need 40 characters. ]
[Question] [ I have a robot. It's a perfectly spherical bot, sort of like the bottom of BB-8. It's around a foot and a half tall and weighs about 15 pounds. I need it to be able to jump on command, no matter which way is 'up.' It should jump at least a foot in the air, although higher is definitely allowed. The mechanism must be fully internal, since anything pushing out of the robot wouldn't work at every angle (only if pointing straight down). No holes can be in the robot, so a rocket system wouldn't work. The current system for movement is that it distributes weight to make the outside shell move. The internals are always right-side up due to gravity. So how could a jumping mechanism work? [Answer] ### Linear motor in z axis So essentially this functions like a monowheel motorcycle except 3d rather then 2d. Then the easiest way to make it jump is have a linear motor with movement in the z axis and significant mass moved. The jump mechanism would be attached to the inner drive carriage which would allow for it to have consistent 'up' direction. Probably something like at least 10% of total mass to maybe 30%. Perhaps the energy storage unit. The higher the mass the more care will need to be for at rest placement of the mass. If that mass is too high position wise, up could become down. Some pattern of moving the mass rapidly will get a jump. To get higher jumps the mass will have to be moved faster. [Answer] /The current system for movement is that it distributes weight to make the outside shell move./ Redistribute weight energetically against the interior top of the sphere. Your sphere contains a weight that can move. It is a hamsterball. To make its sphere jump, the robot hamster pushes off mightily against the inside of the sphere where it is against the ground. It jumps into the air. Now the robot hamster is hurtling upwards within the sphere, squealing shrilly. When its weight impacts the apex of the sphere interior, its kinetic energy is transmitted to the sphere as a whole. The sphere lifts off the ground. Assuming the sphere is elastic to some degree (steel?) it might bounce when it comes back down. Your interior robot hamster will come back down first because it bounced off of the interior apex when it hit. If your hamster can time its next jump to be when the sphere hits the ground, the sphere will rise higher the second time than the first because your robot hamster is adding its energy the second time to some of the energy left from the first. Such a ball could bounce higher and higher with each bounce. [Answer] Lightning. OK, ambiguous answer title, but a sudden high-voltage large-Coulombe charge developed between the centre of the sphere and the outside would have the knock-on effect of creating a charge-differential between earth and the outside of the sphere. The nature of the amount of a single charge is limited by the surface area of the sphere. A flash discharge between the sphere and ground would then result in the expansion of enough of the ground surface-material as a gas-plasma, providing an impulse upwards. Because a single discharge of the sphere's capacity to store charge wouldn't be sufficient to do the job, a fast alternating charge (perhaps in the order of hundreds of thousands or millions of times per second) is continually applied so that repeated strikes up, down, up occur until the desired height is reached. On landing the charges would then be equalised without and within. TLDR: In other words, the robot makes a series of many sparks big-enough to blow it into the air on a cushion of plasma. Stand well clear. [Answer] Springs and winches and a deformable shell So basically your bot will be its core + an omnidirectionl amount of springs + an amount of electric motor-powered winches that are equal to and connected to the amount of springs + a rubber or some other deformable but tough enough material shell. The winches would coil and store power in the springs and then release and uncoil to let the springs themselves uncoil and lead to a force imparted through the shell onto whatever surface, making the ball bot jump. Depending the amount of its sensory devices and the extent of its prediction algorithms the bot may even be able to use bouncing around as its main mode of locomotion instead of rolling though it would still be capable of rolling around anyway by the proper sequences of spring retraction and uncoiling. Add some winch locks and the ball bot would be able to lock in place its bottom or whatever spring while coiled, deforming its shell to have a 'flat' side and allowing it to stay at rest instead of rolling around on unstable or uneven ground. [Answer] Your robot is 1 1/2 units in diameter, and needs to jump 1 unit. If the center of gravity as moved very near the (current) top position, then very quickly moved towards the (current) down position, the movement of the center relative to the shell would mean that in response the shell must move up. if the moveable core is much heavier than the shell, this should result in your desired jumping motion. Since the jump height is less than the travelling distance of the core, it should be possible to achieve the desired height without using flexibility of the shell. A side note: a flexible shell, and/or a lot of "legs" that can protrude when needed would seem a more sensible design in my opinion, since it would allow your robot to remain at rest without constantly applying energy, even in a situation that would be unstable for a perfect sphere. [Answer] Some guys in Shenzen are developing an actual hopping spherical robot. [You can find the paper in ResearchGate for the specifics](https://www.researchgate.net/publication/224118750_A_Spherical_Hopping_Robot_for_Exploration_in_Complex_Environments). In layman terms it uses gears to throw mass around inside itself, and then clever usage of Newton's third law enables it to leap not just upwards but also in many different angles. Here is an excerpt: > > The basic principle of the hopping robot is as follows: first, to drive the energy storage mechanism and accelerate the driving components attached to the mechanism; then the driving components will collide and connect with the follow-up parts of the robot; finally the whole robot jumps at a certain speed abiding by the energy balance principle. > > > If you are willing to allow your robot to deform, you can also take a page from [existing spherical leaping robots](https://www.youtube.com/watch?v=_EBUy0gyE38). Just put a shell over them. --- By the way, in the absence of both [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") and [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") tags, you could also place a cat and a slice of buttered bread inside the ball. When you want the robot to jump, connect the unbuttered side of the bread slice to the back of the cat. This generates an anti-gravity engine. Now connect the mouth and anus of the cat to the inside wall of the robot by using a couple rods and the whole robot will have its mass reduced. Inside an atmosphere this means the lift on the spherical surface will be much greater than the robot's weight, causing it to go up really fast. Disconnect the bread from the cat to have the robot come down again. [Answer] Using rotating masses to release a lot of kinetic energy instantly: Sounds a bit like a more mobile version of the MASCOT experiment: <https://www.dlr.de/irs/en/desktopdefault.aspx/tabid-11302/#gallery/28470> and <https://www.dlr.de/content/en/articles/missions-projects/mascot/mascot-lander.html> The DLR stops a rotating mass to launch this box off an asteroid surface. With more energy and 3 of those flywheels you could angle the jump in any direction. Needs a recharge time of course to spin the flywheels back up. Maybe you could combine this with a linear stage as proposed by [@Gault Drakkor](https://worldbuilding.stackexchange.com/a/223562/30492) [Answer] The idea of how to make this work has been provided in a few answers already, but I thought I'd supplement those answers with some calculations to figure out the rough engineering constraints. We'll base the calculations on the robot containing a linear rail with a weight on it, and a motor capable of moving this weight up and down with a constant force. To make a jump, the weight will start at the bottom of the rail, then be accelerated upwards with the constant force, and slam into the top of the robot. This will transfer the momentum from the weight to the whole robot, which will then jump upwards. I'll assume that the robot is $m\_r$ = 6.8 kg (15 lb), $d\_r$ = 0.45 m in diameter (1.5 ft), and should jump a minimum of $h\_{min}$ = 0.3 m (1.5 ft). Also I'll assume a gravity of $g$ = 9.81 m/s². Our main design variables are the length of the rail, $d$, the mass of the weight, $m$, and the force it is moved with $F$. The length of the rail and mass of the weight are obviously constrained by the mass and diameter of the robot respectively. First, we'll set up an equation for the momentum the system can generate. If the weight is moved the maximum distance with the given force, it will end up with a momentum of $$p\_{max} = \sqrt{F \, m \, d}$$ right before it hits the top of the rail. When this momentum is transferred to the whole robot, it's velocity will become $$v\_r = \frac{p\_{max}}{m\_r} = \frac{\sqrt{F \, m \, d}}{m\_r}$$ Since we want a minimum jump height, we can now figure out how high this velocity will propel the robot. This comes out to be $$h = \frac{v\_r^2}{2 g} = \frac{F \, m \, d}{2 \, m\_r \, g}$$ If we set $h = h\_{min}$ and rearrange the terms, we get the design equation $$F \, m \, d = 2 \, g \, m\_r^2 \, h\_{min}$$ which tells us that the product of our three main design variables must equal a constant proportional to the desired jump height. To take an example, lets choose the rail length to be $d$ = 0.3 m (1 ft), and the mass of the weight to be $m$ = 4 kg (8.8 lb). This gives us a required force of $$\frac{2 \times 9.81 \text{ms}^{-2} \times (6.8 \text{kg})^2 \times 0.3 \text{m}}{4 \text{kg} \times 0.3 \text{m}} \approx 227 \text{N} $$ Another important number to engineer this system is the power requirement for the motor, as this will determine the dimensioning of a lot of the power-train components. Since the robot mass and jump height are given, the total energy requirement is simply equal to $$E = m\_r \, g \, h\_{min} = 6.8\text{kg} \times 9.81 \text{ms}^{-2} \times 0.3 \text{m} \approx 20.3\text{J}$$ If we assume no energy is lost to friction, deformation, etc., we can get the power simply by dividing the total energy by the time it takes for the weight to reach the top of the rail. This comes out to $$t = \sqrt{\frac{d \, m}{F}}$$ giving us a power requirement of $$P = \frac{E}{t} = m\_r \, g \, h\_{min} \sqrt{\frac{F}{d \, m}}$$ Using the same numbers as the example above, the time comes to $$t = \sqrt{\frac{0.3 \text{m} \times 4 \text{kg}}{227 \text{N}}} \approx 0.063 \text{s}$$ which requires a power of $$P = \frac{E}{t} = \frac{20.3\text{J}}{0.063\text{s}} \approx 322.8\text{W}$$ All in all, the numbers work out to this being quite feasible. Since the time of 63 ms to move the weight 1 ft is quite quick, it might not be feasible to build this with a motor and a ball-screw, or a belt, or something like that, but I would guess that for instance a linear induction motor could be up to the task. [Answer] Microfluidic ElectroSpray Propulsion This is a recently discovered form of propulsion generated by using an indium pool drawn through hundreds of needles by an electromagnetic field. The surface tension pulls the melted indium back down, allowing this to function in zero-G. The indium forms into hundreds of tiny cones, the tips of which are overcome by the electromagnetic field, ionized as they pass through, and shoot outward at tens of kilometers per second. If you used a metal with low mass nuclei and weak hydrogen bonding, the ionized particles could pass though the shell and propel the bot "up" because of the sheer number of ionized indium particles racing away at once. [Answer] There is one that is cube shaped. Although not practical, I think same mechanism can be applied to spheres as suggested by others. [Here](https://robohub.org/swiss-robots-cubli-a-cube-that-can-jump-up-balance-and-walk-across-your-desk/) is the device in fully working state. Sides can be closed without affecting its performance. ]
[Question] [ After reading [this post about a sort of translucent biological visor](https://worldbuilding.stackexchange.com/questions/107285/biological-helmet) I was inspired to incorporate a similar design. I'd like to create an organism with a translucent upper cranium, serving no purpose beyond aesthetic value. It would likely have resulted from sexual selection, directly displaying the brain underneath. Is there any biologically occurring material which the translucent section could be made of? Ideally it would have a similar compressive strength to that of bone. Here is an example of how it might look, the humanoid skull in place of a brain: [![enter image description here](https://i.stack.imgur.com/jjTsa.jpg)](https://i.stack.imgur.com/jjTsa.jpg) [Answer] # Take a look at the Tortoise Beetle It has a hard clear shell and the flesh underneath has the ability to change color for camouflage. Since the creature would be larger, it would be feasible for the shell to be stronger and thicker. Beetle shells are normally made of chitin: > > A nitrogen-containing polysaccharide that is a tough, protective, semitransparent substance and is the principal component of arthropod exoskeletons > > > This [question/answer](https://worldbuilding.stackexchange.com/questions/50798/chitin-vs-bone) also gives more insight on how it might affect the being if chitin was used. With the addition of minerals, such as calcium carbonate, the chitin can become even stronger: > > Generally the exoskeleton will have thickened areas in which the chitin is reinforced or stiffened by materials such as minerals or hardened proteins. This happens in parts of the body where there is a need for rigidity or elasticity. Typically the mineral crystals, mainly calcium carbonate, are deposited among the chitin and protein molecules in a process called biomineralization. The crystals and fibres interpenetrate and reinforce each other, the minerals supplying the hardness and resistance to compression, while the chitin supplies the tensile strength. Biomineralization occurs mainly in crustaceans; in insects and Arachnids the main reinforcing materials are various proteins hardened by linking the fibres in processes called sclerotisation and the hardened proteins are called sclerotin. > > > A hybrid of nail and chitin reinforced with calcium carbonate would be ideal so that way the shell could give slightly and not shatter from impactful attacks or accidents. Like the beetle, the brain could have the ability to change colors for camouflaging against arial predators. [![enter image description here](https://i.stack.imgur.com/M1l9x.jpg)](https://i.stack.imgur.com/M1l9x.jpg) [![enter image description here](https://i.stack.imgur.com/zVF02.jpg)](https://i.stack.imgur.com/zVF02.jpg) [Answer] You're looking for this chap [![enter image description here](https://i.stack.imgur.com/UeP7w.png)](https://i.stack.imgur.com/UeP7w.png) <https://video.nationalgeographic.com/video/news/transparent-fish-video-vin> The Pacific [Barreleye](https://en.wikipedia.org/wiki/Barreleye) Fish > > All species have large, telescoping eyes, which dominate and protrude from the head, but are enclosed within a large transparent dome of soft tissue.[5] These eyes generally gaze upwards, but can also be directed forwards.[6] The opisthoproctid eye has a large lens and a retina with an exceptionally high complement of rod cells and a high density of rhodopsin (the "visual purple" pigment); no cone cells are present. To better serve their vision, barreleyes have large, dome-shaped, transparent heads; this presumably allows the eyes to collect even more incident light and likely protects the sensitive eyes from the nematocysts (stinging cells) of the siphonophores, from which the barreleye is believed to steal food. It may also serve as an accessory lens (modulated by intrinsic or peripheral muscles), or refract light with an index very close to seawater. Dolichopteryx longipes is the only vertebrate known to use a mirror (as well as a lens) in its eyes for focusing images.[7] > > > [Answer] Glass is quite hard. If set against a proper surface, it can resist compression really well - set a window pane against a hard enough table and it may resist hammer strikes which would otherwise break it. So a cranium of glass amalgamated or layered with [hyaline cartilage](https://en.wikipedia.org/wiki/Hyaline_cartilage) might do the trick. If you think glass would be unusual for a living creature's skeleton, meet the [Venus Flower Basket](https://en.wikipedia.org/wiki/Venus%27_flower_basket), a sponge from Southeast Asia seas. [Answer] Although there exist various valid answers already, I'd like to suggest that there be some sort of rib cage in the cranium. I.e. instead of the entire cranium being a semi-hard, translucent material (tortoise beetle shell); there would be a matrix of very hard, opaque ribs (with gaps to show the brain), and a semi-hard, transparent material on top of it. It is unlikely that sexual selective forces are going to select this trait if survival forces are weeding it out at a higher priority. At least in the experience of humans, an excessively brittle skull would not be well-selected by evolution. But this composite design that I'm suggesting would improve survivability and still reveal a peak at the brain. However, beware that direct access to seeing a brain is not necessarily a sensible criteria for sexual selection. Brain size wouldn't necessarily correlate well with intelligence, and we also get a reasonable estimate of brain size from head size. I think brain health is more important (e.g. have traces of lead caused diminished IQ?). So I think the view that they want to see may not be brain size; it may be brain color, how wrinkly the brain folds are, and other brain health indicators that may be applicable to the species. [Answer] tl,dr - Anything strong enough the properly protect the brain will likely not be terribly see-through, and vice versa Fingernails are somewhat translucent, so that might be a material that could fill the bill. horns and tusks are pretty durable, but I don't know of any that are clear enough to see through. The obvious issues center around the idea that such a material could expose the the brain to damage if it's not strong enough, and if it renders the brain visible, would presumably expose it to UV rays, which could cause damage over time as it does to the skin. ]
[Question] [ I was wondering what benefits are granted when a sword is either on fire or emitting flames. I once read that such a weapon would be completely useless, as it would cauterize any wounds it inflicts, but there has to be some benefit. What are the advantages of a flame sword in melee combat? [Answer] While a flaming sword would certainly have a psychological effect on people, unless it was emitting a white hot flame (@ 1600 degrees C), it would not be as effective as a metal sword. Consider that the mechanism of injury would have to be the transfer of heat to the target. A red hot sword (at a mere 800 degrees C) would have to be held to the target for a period of time, more like a branding iron than a sword, in order to transfer enough heat to cause injury. If the target is protected by armour, then the mass of metal and the protective undergarments need to be heated enough for the heat to transfer through them first (and the masses of metal, leather and quilting would both spread the heat energy and provide insulation to the target as well). A red hot sword would also be far too cool to melt metal armour, and would have difficulty setting fabrics on fire with a mere swipe or quick thrust. Since the padding was usually sheep's wool, flammability isn't going to be an issue. Even striking a shield isn't going to cause a catastrophic ignition event, try setting a sheet of plywood on fire with a quick sweep of a blowtorch and you will get the idea. Indeed, you can quickly swipe a blowtorch across your own naked skin and feel the heat or suffer a first degree burn, rather than cutting through your arm... Greater heat allows you to overcome these issues to a certain extent, providing much more energy to transfer to the target, but in general, a flame sword would have to be used differently from a metal one. The best attack would have to be a thrust with the flaming blade to the face, since even the best helmets need to have openings to allow for sight and breathing. A successful thrust could blind the enemy, or they might breath in the flame, both rather horrifying ways to die. Given the relative lack of effect of a flaming sword, the terrible deaths that it does provide and the pretty instant identification of the user once drawn, I suspect that a flame sword would simply invite the wielder to die under a hail of crossbow bolts, followed by attacks by polearms so the men at arms will be at a safe distance but still able to strike killing blows if the archers hadn't gotten him first. [Answer] For a few years I learned how to fight with medieval weapons. Some people I met then had their swords put on fire (in this case, with oil on a wick, so it was for a short time) It was beautiful and impressive ! But not very effective. Of course they did not use it to fight an army for glory. It was a choregraphic fight and the "enemy" should not be hurt or frightened. The public was impressed, the noise of the flames and the light were spectacular, but the fight itself has to be quite slow and simple. The flames are as dangerous for the owner of the sword than they are for the opponent. If you want to protect yourself in a swordfight, you have to keep your sword very close to you. Keep your hair tied and protected, and make sure your clothes won't ignite. And you will have to wear good gloves, as your wrists will stay very close from the heat during the whole fight. As long as you move quickly there is no problem, neither for you or your opponent (as it has been said, the heat don't hurt you if you don't let it on your body for a moment), but in a real swordfight your swords will meet, and stop, and then move again. Your opponent's moves will bring your own sword to protect you, thus put it very close of your head, your eyes, and you don't want flames near your eyes. Perhaps, if you manage to hurt your opponent with your flaming sword, it will hurt him more than a regular sword. Burns are very painful, but so are "regular" sword injuries. If you manage to hurt your opponent, a flame sword will be a little more cruel, (burns are painful and take a long time to heal) but it won't help you win the fight, except if your opponent is terrified by your mighty flaming sword and run away as soon as he sees it. [Answer] God thought it was a good idea. > > So he drove out the man; and he placed at the east of the garden of > Eden Cherubims, and a flaming sword which turned every way, to keep > the way of the tree of life. Gen 3:24, KJV > > > You think you are wiser than God? I think the intimidation value of the fact that you are so butch that you do not just use a sword, but a flaming sword has to be worth something. Humans and animals justifiably have a deeply held fear of fire. It burns us, and often escapes our puny attempts to control it. A weapon that your enemy fears works even when you don't have to wield it in combat. Whether the flaming sword gambit is a good idea for a human wielder is perhaps a different question. One clearly negative aspect of a flaming sword is that you are compromising the strength of the metal. At temperatures above 900 C, steel loses about 90% of its strength. This is very bad for battlefield use. Human soldiers are not as butch and do not have the superior grade weapon material qualities of angels wielding divine swords. Lose the flaming sword. Lastly, if you are primarily interested in a torch with limited utility as a weapon, well perhaps you are using the right tool after all. --- In case English is not your first language. Describing an angel as butch is a whimsical means of describing angels as extremely manly, possibly an irreverent usage. Butch does not necessarily reflect common modern usage as manly lesbians. My only intent was making this light-hearted, no offense was or is intended. I simply intended a light-hearted description to counter the idea that I was engaging in a serious theological discussion. Clearly worldbuilding is not the place for that discussion. [Answer] A flaming sword can't be grabbed Though it's not often shown in movies and fantasy games, grabbing the edge of a sword (your own or your enemy's) was not uncommon. Sometimes a knight would flip his sword around, grab it by the blade and swing it like a warhammer (the mordhau maneuver). [![mordhau](https://i.stack.imgur.com/Slo6h.jpg)](https://i.stack.imgur.com/Slo6h.jpg) (source: [warosu.org](https://i.warosu.org/data/tg/img/0257/80/1372809646575.jpg)) Sharp blades would deflect off of full plate armor, but the concussive force of a blunt weapon could transmit through the steel and hurt the knight inside, or perhaps dent the armor and immobilize him. A sword with a burning edge probably could not be grasped (unless your warrior also has asbestos gloves). This would make maneuvers like the mordhau impossible, restricting the sword's utility. However, a flaming sword would also be difficult for the enemy to grab, changing the tactics a foe must employ. [Answer] 1. Psychological and morale effects. It's going to get people's attention and intimidate and surprise them and make them wonder what's going on, and probably inspire some fear and confusion. Also, metal doesn't usually burn, and flaming oil also doesn't burn well when put on metal and swung about. So if you have a seriously-burning sword, it's going to make people wonder what's going on, at the very least. It's not going to look like something most people will want to risk getting hit with. Not to mention that you may make people wonder if you have some sort of supernatural assistance. Your foes may cringe, flee, falter, freak out, or at least be thrown off their usual behavior. People on your own side may also quite like having you on their side - you may inspire them, or at least they may like that you are attracting so much enemy attention. 2. Hot metal hurts to touch, so people you cut may suffer additional pain. 3. You can now easily set flammable things on fire. If your sword produces plenty of fire even while swinging around, it probably will light up cloth and straw quickly, which might be useful. If an enemy is for instance in metal armor under a nice cloth surcoat, for instance. Or perhaps you are pillaging, or want to create a fire obstacle, and there's dry grass or hay around. 4. You won't have to worry about darkness. 5. Animals in particular may not want to attack you. You might be able to spook someone's warhorse. 6. However you are managing a flaming sword, may also be an advantage. For example, if it's covered in Greek Fire or some sort of pitch/tar, that may also add pain and flaming sticky goo to anyone you hit. Or if it's flaming because it's magic, the magic may also make it more effective in other ways. Or if it's flaming because some god of fire has blessed it, his blessing may also have other effects... [Answer] Really, the power of a flaming sword beyond the merely psychological would be entirely dependent on the properties of the sword in question. Since the others have basically answered your question with the 'no' answer, allow me to be contrary. First of all, since the sword doesn't burn itself into a wreck while being ablaze, we can safely assume it is a magical blade, or at least emits magical fire. If so, perhaps it protects its user from its own flame. If it does, this expands its possibilities by a huge amount. 1. We can increase the blast radius of the flame, turning the wielder into a literal cyclone of fire. This would provide incredible area control, as you could threaten a large group of people just with this sword. 2. Alternatively, the blade could be ridiculously hot, like arc-welder hot, enabling its wielder to cut through men and walls like a literal hot knife through butter. So yeah, maybe a bit too fantastical for your liking, but probably cooler than a normal sword ablaze in burning pitch. [Answer] Here's a magic-free (if rather impractical) solution. Perhaps you could have a sword with a fuel delivery system built in. You'd need a pilot light always burning -- that could be fed by a wick -- then a trigger to release a dose of fuel down a hollow blade. That would mean that you could block without the flames coming too near you, and still deliver serious burning damage. Despite the ancient use of [Greek fire (wikipedia)](https://en.wikipedia.org/wiki/Greek_fire) it wouldn't be a good fuel in this case as it needed significant preheating. Even better would be [pyrophoric (self-igniting) liquids (wikipedia)](https://en.wikipedia.org/wiki/Pyrophoricity#Liquids). Again you'd need manual control of delivery. When it comes to how it would be used, either way you'd have a short-range flamethrower combined with a sword, not so very different from a [pistol-sword (wikipedia)](https://en.wikipedia.org/wiki/Pistol_sword), but with the psychological effects of fire weapons. The flames could be used mainly before joining in close-combat -- perhaps they would spread far enough to be useful against an enemy with pole-arms. Against an armoured foe, the flames could be quite effective, similar to how flame-throwers were [used against bunkers (wp again)](https://en.wikipedia.org/wiki/Churchill_Crocodile#Service) to great effect. Essentially because the flame can enter though any opening in the armour and then spread it can cause serious harm without the need to penetrate armour. Flames passing in through existing openings/joints, even if only painful and not lethal, would certainly affect an opponent's ability to fight (especially considering eye-slits). If a sword could open up a new hole in the armour then inject flames, it would be all the more effective. The fear factor involved with fire might mean it would be used as a torture weapon as well. A reservoir would have to be reasonably well protected, as would the fuel line, otherwise damage to the fuel line would be a serious vulnerability, especially with pyrophoric liquids. [Answer] The overall advantages of each Normal Sword: simple Flame Sword: complicated Flame-thrower: longest range and largest area of effect --- Flaming swords, as we currently think of them, involve many complications without any "real" advantage over other weapons which use the same concepts. This makes the complications its strength, because hopefully people won't understand what they are facing and they will be afraid. * Fuel and overall design * Blade integrity (hotter usually means softer) * Danger to self * Relatively more training compared to both normal swords and flame-throwers. * Doesn't seem to solve a real combat problem, due to not being any more effective at causing harm compared with a normal sword? *But let's say we could* have an effective flaming sword, what would it have to be like?** * Probably operates basically like a lightsaber from Star Wars - complete with advantages of burning through most things near-instantly and easily while requiring little or no fuel. Of course.. the real problem with that is the tech level involved. If a lightsaber just randomly showed up on the battlefield today, the user would still just get shot. If it randomly showed up in a medieval battle, I suppose the person would still get shot with arrows. Randomly showing up at a medieval duel? I guess you've found the right moment to pull it out, so long as you are more likely to be portrayed as the son of a deity rather than an evil demon. [Answer] JET PROPELLED CUTS What if the flames engulfing the sword dinamically flow on the sides of the sword giving aaddictional thrust like a spyke thruster engine (more correctly a linear spike engine like the one made as prototipe for the x project spaceplane... Sorry i forgot the name of the Xproject) In coordination with the wielder moves it could ad more power to the hit, a more acurate edge alignment (since the sword are automously directing themselves) and if the thrust controll of the wearer are fine enough are possible to perform some "impossible" moves and angles of attack The issue is how you could have controll over the sword and after that the handling of that sword need a completely new skill set, almost a new martial art ]
[Question] [ Current Bank security is based on encryption, once quantum computing or another system to break security is invented all banks are unable to securely transfer money digitally. Assuming banks are unable to find a new form of digital security, digital inter-bank transactions (a vital part of a modern economy) will cease, and all digital currency (including BitCoin) will effectively fall to zero value. When this happens, what will be the new currency in the world? Gold? Cash? Barter system? If the old currencies were to persist, how would transactions be handled? [Answer] Money is chosen because money is convenient. Current prevailing opinions suggest a [four major factors](http://www.amosweb.com/cgi-bin/awb_nav.pl?s=wpd&c=dsp&k=money%20characteristics) that affect the choice of a money: * Durability: The currency should avoid devaluing over time * Divisibility: It should be possible to use the currency for arbitrarily small transactions. * Transportability: It should be easy to transport a great deal of wealth * Noncounterfitability: It should be hard to create fake money. In your scenario, the last hold-out of the banks, quantum cryptography, fell, leaving non-counterfitability no longer feasible. You want to know where it goes. I'm assuming by your "apocalypse" tag that we should make this worse than the question actually asks for. Let's say QM crypto took a long time to break, and along the way we figured out how to make gold from carbon, etc. Lets drag the concept of currency all the way back to its basics. Money is funny in that its primary purpose is trade. However, there is no reason its ONLY purpose is trade. Several cultures in the Americas used [Cacao as currency](http://encyclopedia-of-money.blogspot.com/2010/01/cocoa-bean-currency.html). Yes, in that era, money actually did grow on trees. In some cultures, it was even so valuable that the peasants could not afford to drink hot chocolate -- it was a noble's drink simply because it cost too much to prepare! This shows the simplest layer of money: an object that can be used by a sufficiently large portion of the population as to develop value. This is known as "[commodity money](http://en.wikipedia.org/wiki/Commodity_money)." Cigarettes in POW camps is another common example of this sort of money. Even those who did not smoke accepted cigarettes as currency because they knew they could use them to trade with those who did smoke. In this incredibly perverse apocalyptic world, there is one thing which should still hold value: energy. If we have enough energy capabilities to uproot Gold from its platform, we have certainly learned a thing or two about storing energy. Large powerful batteries would easily form the basis for a energy based currency. They pass all of the standards: * Durability - Large batteries in this highly technological world would not deplete easily. * Divisibility - Limited only by quantum particle limitations, energy is virtually perfectly dividable across any number of stores. * Transportability - We're handwaving this until the next argument. * Non-counterfitability - Nobody has figured out how to counterfit a Joule yet. --- But what if energy is hard to transport? It would be a strange apocalypse where energy is hard to transport but gold is forgable: this might even qualify as a utopia to some people. Accordingly, I'm going to assume that either batteries or gold is a valid form of storage. Once you have a physical good like a battery or gold, banks can come back into play. Right now we accept that we can put a dollar into bank A and withdraw it a thousand miles away in bank B. Crush all of our crypto algorithms, and this is no longer a safe assumption. Accordingly, each bank would have to be responsible for its own reserves, gold or energy alike. It would issue a certificate for each deposit. Bank deposits are tied to their physical location, and have to be moved by bank order if you wish to withdraw them elsewhere. These certificates are safe, even in the presence of QM crypto breaking capabilities. They can function as a shared secret, with a random string of characters identifying each certificate. This shared secret is invulnerable to QM because owners of these certificates are advised to never place the strings in a hackable storage medium -- a physical safe would be best. Both the owner and the bank know the shared secret, but this secret is never transmitted until the withdraw is made. No cryptography can break such a system. --- The resurgence of trust frees banks from this physical good trap. To make a withdaw from a far-off bank, you would have to give the local bank your certificate, and have a new one issued which says "in X days, when the banks re-distribute goods, this certificate is good for Y energy/gold." You then have to sit and trust the banks... but we rather trusted them already. There is a funny aspect to these certificates, which is that they are easy to transfer with a little trust. If you trust that a certificate is not counterfitted, you can simply assume ownership of the certificate, and withdraw the goods at a future date. If you trust that a bank will actually transfer the resources, you can even accept one of those futures certificates used to tranfer resources. This will rapidly lead to a trust-based economy, where it is possible to forge a certificate, but it is rare for this to occur because the entire culture values the simplicity of being able to trust certificates. With this step, you have boot-strapped the gold-standard, for you will have pieces of paper which have a promised value in gold or energy. --- Think that utopian ideal is unlikely? Guess again. We humans are far more creative than most recognize. Let's shave a little off of the durability of the certificates every time we trade them: let's say 0.11% of the transaction cost. In exchange for that durability, we can fund a community whose sole job is managing the currency for us. When a transaction is fraudulent due to a poor certificate, they will investigate. The merchant will usually be held responsible, because they have the most ability to cope with such a burden, but sometimes the community absorbs the cost. Consumers can feel safe because they know that, even though the merchant may hold a set of numbers which can make any arbitrary charge they please, merchants don't. If they did, the community would find out, and revoke their membership in the community. * Durability: The value of the transaction only depreciates 0.11% each transaction * Divisibility: The value is represented as a number which is written down, so it is arbitrarily divisible. * Transportability: Only a few numbers are needed on one's person to have access to their entire life worth * Noncounterfitability: There is an entire community dedicated to ensuring this is not an issue. It happens from time to time, but the system absorbs such costs. Sound familiar? This system is called Visa, or MasterCard. It is in use today. Welcome to the apocalypse. [Answer] Your question is based on a flawed premise, so the answer is: nothing will change, except for technical details that you don't understand. Bank security is not based on a computer's inability to solve quantum computations in a reasonable time. First of all, cryptography is only one aspect of bank security. Second, quantum computers (if they are at all possible in a form that would affect common cryptographic algorithms, which [is not a given](https://crypto.stackexchange.com/questions/436/now-that-quantum-computers-have-been-out-for-a-while-has-rsa-been-cracked)) would not invalidate the principle of cryptography; they would only require [new algorithms that people are already working on](https://crypto.stackexchange.com/questions/tagged/post-quantum-cryptography). If, for some reason, there was an (extremely unlikely) breakthrough in our understanding of computation which led to invalidating the very principle of computations that are easy to verify but hard to carry out without knowing a secret, then much of cryptography would become impossible. However, [one-time pads](http://en.wikipedia.org/wiki/One-time_pad) have provable security: their security is a fact of mathematics, unlike other cryptographic algorithms whose security relies on the fact that none of the world's smartest cryptographers have been able to break it after years of trying really hard. In this event, securing and transporting one-time pads would become an important industry. Another consequence is that technologies ensuring communication confidentiality and integrity through physical rather than mechanical means would flourish — not only fast courriers but fiber optic channels where eavesdropping is detectable. A collapse of the banking system as such would require significant social upheaval, not just a scientific or technological breakthrough. It's impossible to predict the consequences because they depend on what that social upheaval is about. Should it involve a collapse of the fiat currencies that are represented by bits in computer memories backed to some extent by physical objects with a fiat value shadowing their production cost (gold and silver), we would likely turn back to the previous system of fiat currencies that are represented by writing on paper backed to some extent by the same physical objects. [Answer] Quantum computing won't be "solved" in a single stroke. It will become possible, for a small number of bits, to solve problems in parallel. So an 8-bit quantum computer will be able to test 256 solutions simultaneously. As technology improves, the number of bits will increase, but there will always be a limit where reliability becomes the limiting factor, and the number of useful bits cannot be increased without improvements in technology. Encryption has always been easier than encryption-cracking, and always will be. The same quantum computers that can crack 256-bit encryption in 1ms could be used to create 100,000-bit encryption and come up with million-digit prime numbers. So as computing capabilities improve, encryption *and* encryption cracking will improve at a similar pace. This is what has always happened in the past. From my experience in the industry, the limiting factor will be the banks! When *"known encryption systems become obsolete"* the banks will be the slowest to respond [Answer] The only portion of bank security that is dependent on cryptography is online access. If cryptography fell without replacement, then banks would no longer be able to offer online access. This would be true regardless of currency. I.e. even if we switched to commodity money, we still wouldn't be able to do online transfers. Bitcoins are an interesting area in regards to this. As a cryptographic currency, they would be impacted. The immediate result would be that the rest of the Bitcoins would be mined. Instead of a growing money supply, there would be a static amount. This is something that would happen eventually anyway, so not that big a deal. More importantly, all Bitcoin transactions use cryptography to authenticate transactions. They'd have to find another way to do that, since cryptography would no longer be secure. So how would we do things like shop online? We'd have to come up with a process that put those portions that need to be secure offline. For example, perhaps you shop on Amazon.com and get a cart ID. You then call your bank on the telephone (not VOIP) and tell them that you authorize that cart ID. The bank phones Amazon.com with the authorization and other private information (e.g. your address) which then fetches your order based on the cart ID and processes it. Note that under this system, Amazon.com has two networks: a public insecure network and a private disconnected network. Because private information is only available on the private network, this is secure without cryptography. Well--at least as secure as phone ordering ever was. Credit card transactions could no longer be processed online. We'd be back to processing them by phone. Phone processing would not be impacted. Physical transfers of paper money would not be impacted. Presuming we're only talking about public key cryptography, parties that communicate online frequently could still manage. They'd just have to do the initial handshake offline so that they can exchange private keys rather than public keys. This would be suitable for long running connections where the increased cost can be amortized over time. It wouldn't work well for short term or intermittent connections, e.g. online shopping by individuals. [Answer] Quantum computers will make some public key algorithms insufficient and cast doubt on others. It doesn't help much for symmetrical encryption: [By existing estimates, bruteforcing 256-bit AES key on quantum computer is equal to bruteforcing 128-bit AES on a classic computer, so security levels remain very high.](http://blog.kaspersky.com/quantum-computers-and-the-end-of-security/) However, the same technology offers new abilities on the side of the secret keepers, too. Quantum encryption relies on the no cloning theorem to prevent eavesdropping. The first description of quantum cryptography ideas was an example using currency! If I recall, it proposed using 20 quantum traps on a banknote as a way of preventing counterfeiting. Maybe that's enough detail to find the original paper? More generally, you can do weird and wonderful things like produce the correct answer only if you forget the question, providing for tamper-proof decoding machines that can't be looked into to peek at the workings. Quantum computers are not an oracle even for classical algorithms. The class of problems is now understood and called [BQP](https://www.wikipedia.org/wiki/BQP). [Answer] current public/private key cryptography is based on the fact you have a massive number (256, 512, 1024.. bits ) which is your public key you give out and publish openly and a private key which are the two numbers that multiply together to make this number (and which you keep really safe!) A New form of math that could factorise this public key into its two multipliers in a reasonable time using current state of the art computers (including quantum computers) would either mean we have to go to much bigger numbers (128K, 256K.. bits) which would take longer to factorise (and longer to process), some new cryptography or as stated above another method entirely. I personally think Peter Hamilton got it close when the AI took over the banking and removed humans from the equation as lets face it we are the weak link in any transaction system and always will be. [Answer] Money will never disappear. Neither will banks. They may change and take on a different guise, but as long as there is human society there will ba money. Banks and encryption are simply the latest in a very very long line of technologies used to allow human beings to spend there wealth. If the entire digital banking system were to collapse, it would be a surprisingly short period of time before something else emerged. I would give people a week before they start bartering goods and services & products of universal value such as jewellery. Barter is the most fundamental system and is used all over the world today anytime currencies become unstable, such as the present day in Russia ]
[Question] [ In many fantasy settings, soldiers (generally orcs) ride on wolves the size of horses, plundering and raiding to their hearts' content. The only issue I see with this image (aside from using a carnivorous mount) is that it is almost never stated where these giant wolves come from. If one thinks about it, what is the ecological niche of such a large canine in the first place? Is short, what are the ecological niches a giant wolf would occupy? Assumptions: * It's a part of the family Canidae * Is the size of a horse 1.4m to 1.7m [Answer] ## Grasslands Large Game Predator [![enter image description here](https://i.stack.imgur.com/wke5t.png)](https://i.stack.imgur.com/wke5t.png) Epicyon haydeni is the largest ever species of true canine. It was only a bit more massive than largest canines today. It lived in the Great Planes region of North America filling more or less the same niche that lions do in the African Savana today. Unfortunately, this is a good bit smaller that a horse, but there is a much larger pre-historic animal that looks and acts a lot like a wolf that could easily fit the role of you wargs. [![enter image description here](https://i.stack.imgur.com/pUN0i.png)](https://i.stack.imgur.com/pUN0i.png) Megistotherium osteothlastes were a species of Hyaenodontidae making them not related to Wolves at all, but their similarities are enough I think they make a good candidate for this answer. These creatures lived in what is now the Sahara Desert, which was at the time, very similar to how the African Savanna is today. Weighing in at 300-650kg, these creatures fit well within the size range of a typical racing horse. So what did these larger than modern animals have in common? Open grasslands and suitable large prey. Epicyon haydeni had access to various species of horses, camels, and rhinoceroses which would have been as large or larger than most prey that modern wolves hunt, and remains of megistotherium osteothlastes found alongside Gomphothere, suggesting that they hunted these distant cousins to modern elephants. So, if you want your setting to have horse sized wolves using modern prey, putting them along side plentiful populations of too-big-to-hunt otherwise herbivores like elephants, hippos, and/or rhinos is probably the best way to go. [Answer] With that size it would compete with bears (130 to 190 centimeters) or big felids like lions and tigers, and would probably end up occupying similar ecological niches. The actual niches strongly depend on the anatomical features of the creature, which you don't mention. For sure, due to its size, it would need to be the apex predator and would need to have a large feeding base to ensure its sustenance. It might also become an omnivore like the bear is, in order to increase its chances of finding food. [Answer] Bigger wolves, bigger preys A normal wolf needs 2.5 pounds of food every day. If wolves become the size of horses, then their prey will also become bigger i.e. bison sized deer, or bison in large sized herds. This is necessary for their survival. Wolves are sometimes omnivorous [This](https://rangerplanet.com/what-do-wolves-eat-complete-list-of-what-a-wolf-preys-on/) article mentions that > > Most nutritionists agree that a wolf's diet consists of around 60% > meat and 40% plant material. This varies according to seasons and > other factors. > > > This article explains wolf diet in winter, spring, summer and fall. [Answer] Well, given what you say, it sounds like their ecological nice would be a domesticated animal. Many draft horses are big, lumbering beasts. They have no ecological niche in the wild, they exist because humans bred them to serve as beasts of burden. There is no reason to think things would be significantly different for riding wolves, such species could be selectively bred for size and other requirements. A grey wolf (the largest extant canid species today) can grow to about 92cm, roughly 2/3 of your target size. That scale difference is not too different from the difference between a normal riding horse and the largest draft horses, so it’s probably doable without issue. --- On a side note, being carnivorous is not likely to be as much of an issue as you think. No canid is an obligate carnivore, and there’s no reason to think that your riding wolves would be either. Yes, they would need a lot of food, but that’s not actually too different from a horse, and a large chunk of that could be grains or other plant products (just like dog food in real life). Tolerance of a more plant-based diet is something that could even have been actively selected for during breeding. [Answer] It's probably a scavenger. The fact that "regular" wolves get no where near that size is a hint that the costs to being that size -- lessened agility, higher caloric requirements, etcetera -- are not "worth it" in terms of evolutionary selection. For that reason, this larger wolf is probably not a pack hunter like a "regular wolf." I'm not up to date on this issue, but I remember a theory going around that the tyrannosaurus must have been a scavenger for much the same reason that your wolf would be. It's size would have made hiding/sneaking more difficult and fast chases downright dangerous (due to risk of injury). On the other hand, the size does make it scary and likely, then, able to scare smaller predators off kills that they made. If you don't like the scavenger angle, I see one other obvious one. Big cats get much closer to horse-size than wolves. I think tigers are the biggest, but lions are close and socialize much more like wolves. I don't have the expertise to say why they ended up being so much bigger. My guesses range from bigger prey to different (likely more effective) hunting strategies to competition with other large predators/prey that created an evolutionary arms race (e.g. for lions: hippos, water buffalo, rhinos, etc. are a lot scarier than deer -- for tigers: they've been known to kill grown crocodiles, water buffalo also, etc.) to intra-species competition. If you feel like you find a satisfying explanation for the wolf vs. big cat size discrepancy then you may be able to adapt it to your purposes. Personally, I think the scavenger angle is much more plausible. Dogs and cats have significantly different builds and I don't imagine the wolf building scaling as well as the cat's, much less scaling to be 2-3 times the size of the largest cat. Edit: It occurred to me shortly after writing this that it's also plausible that the wolves were artificially selected-for/bred for size. Medieval knights did this with horses, so there is a direct historical analogue. When I came back here to check whether this explanation fit into the parameters of your question I noticed that a commenter made a similar note about breeding. I decided to add this to my answer anyway because it may be important to you that war horses, not just draft horses, were also bred selectively since that is a better match for your setting. Personally, I still like the scavenger angle. I would use that or maybe have them be large scavengers that have been bred to be even larger by orcs. It feels really unlikely that a "regular" wolf could be bred up to 10-20x it's size. On the other hand, if your scavengers were already 5x the size of a "regular" wolf then why not try and make them a little bigger still? I think those two ideas could complement each other. ]
[Question] [ I have a character who is involved in the typical, secretive supernatural shenanigans of my setting (think something like a superhero, a monster hunter, or the vampires in Vampire: The Masquerade) but has a day job as a medical doctor in a Western country. Being a doctor is their main job, as their supernatural work is mandatory (they have no choice in the matter) but doesn't pay anything. The supernatural is also not medical-themed in this setting so it is not like they are doing medicine by day and fighting plague demons by night that might lend them to a particular area of medical specialization. The problem with being a medical doctor is you often have long hours and you don't get to choose when you get to work. Sometimes you have to work ER or operating room shifts and if you live in a small town and are the only doctor you will get called in every time there is an emergency, even if you are a general practitioner. And before that being a med student often demands long hours and work in very difficult positions. At the same time, you can't ignore the plot when it comes calling if you are a superhero, monster hunter, etc. People will die if you're a doctor and don't operate on them, but they will also die if you ignore the supernatural nonsense that is killing and eating people. While that conflict makes for good tension in small doses if it happens often enough you have to wonder how the character keeps their job, especially since doctors can get in big trouble if they don't fulfill their duties enough times. On the other hand, the character wants and prefers to be a doctor, despite being drafted into dealing with the supernatural (which they don't like), so the character is unlikely to say "well, my life situation prevents me from having a career in medicine". This is a common trope for people living a double life in supernatural fiction (e.g., Spider-Man and Daredevil have this as chronic issues), but I've never seen it done with medicine. I'm trying to figure out what branch of medicine would be the best one for this person to be in, given they already have the commitment of dealing with supernatural issues before they even enter medical school. I.e., what branch of medicine/medical career would be the most amenable for someone hiding a supernatural secret and occasionally having to take unexplained absences? I'm asking this here because there isn't really a good real-world analogue for "doctor has to moonlight by fighting evil". About the closest I've been able to find is when doctors have chronic health issues, but having talked to IRL doctors usually what they do in these cases is power through the health issues and do the job anyway. For most doctors I've talked to practicing medicine is often the first and primary concern. This is a case where issues come up that the character simply cannot back-burner for the sake of their job. [Answer] # Pathologist: This field of medicine often involves a lot of time in an office looking at tissue and other THINGS that get pulled out of people. You diagnose cancers, rare diseases, and the like. There are a LOT of tests involved, but the pathologist just orders them - they don't do many real-time tests. Further, of all fields of medicine that I've seen, they require the least direct patient care. Often they hand down pronouncements from on high that the regular doctors then need to deliver. The good ones talk to patients. The bad ones get away with not doing it because it isn't required. The work that does get done is often not on a specific schedule. I've watched many pathologists keep strange hours late at night and on weekends to cover their needs. So if your pathologist keeps weird hours but gets all his/her work done, no one really cares that much. Certain specific things in hospitals might require a pathologist to be available and on-call, but pick and choose the position and that need can be avoided. Further, if there is a masquerade to maintain, then all the dead werewolves and vampires show up in the morgue where - you guessed it - a pathologist is usually performing the autopsy. The report can just gloss over the unimportant details of the pronounced overbite and fangs, and focus instead on the gunshot wound and silver knife protruding from the chest (did I say silver? No, that was steel...). Some places have special vehicles or parking passes for people who work in the coroner's office. They are kind of part of the team responding to crimes. No one questions if a coroner is at the scene of a death. Wow, how did you guys beat the ambulance here? So if you need a doctor's job where they can disappear at a moment's notice and no one so much as blinks, where they have their hand controlling medical reports that might embarrass the powers-that-be, keeping nocturnal hours if required, then nothing beats a pathologist. * PS. Telling everyone you volunteer for Doctors Without Borders can explain those sudden long absences where your character is unavailable helping somewhere in sub-Saharan Africa out of reach of cell phones. As a pathologist you can say you are using your specialty at any time. Sorry, I'll be gone an extra week. I was exposed to ticks infested with the newest fever in Madagascar and have to isolate. [Answer] Personal Physician Having someone whose health they are personally in charge of would naturally take priority over a general practice as well as provide an excuse for for failing to answer a call. Better yet, if their charge was (or believed to be) wealthy, the priority could be explained as a means to fund the general practice. [Answer] Short Term Locum Your hero works as a locum doctor. They take short term contracts of several days or weeks across different hospitals. They usually end up replacing someone else who got a minor illness like the flu or bitten by a dog. Switching hospitals is a good way to keep a low profile and stop people noticing irregularities in your work schedule. [Wikipedia](https://en.wikipedia.org/wiki/Locum) says there are thousands of locum doctors in the UK so this is a normal thing to do. In the middle of crime season they tell their locum agency they are not taking any more contracts. The agency doesn't care. It has thousands of other doctors to find places for. Which specialization is best -- well whatever one leads to its doctors getting sick most often! [Answer] Toxicologist/herpetologist Q: Why the 3-week absence, fang scars, and mysterious vials in your office? A: I had to fly to Sydney, track some taipans for a few days, then extract their venom. [Answer] Hospitalist. <https://www.hospitalmedicine.org/about/what-is-a-hospitalist/> > > What is hospital medicine, and what is a hospitalist? > > > Hospital Medicine is a medical specialty dedicated to the delivery of > comprehensive medical care to hospitalized patients. Practitioners of > hospital medicine include physicians (“hospitalists”) and > non-physician clinicians who engage in clinical care, teaching, > research, and or leadership in the field of general hospital medicine. > Hospitalists manage and treat a significant range of complex and > comorbid disease conditions. Hospitalists typically undergo residency > training in general internal medicine, general pediatrics, or family > practice. > > > Hospitalists are usually internists and they work shifts. When it is not their shift they don't get called. Also they can pick up shifts as they choose; hospitalist work offers flexible hours and so is attractive for a new mother or physician who has other life committments, including fighting evil. Hospitalists are also largely interchangeable and will hand off their patients at the end of a shift to an incoming hospitalist. I can imagine your character's long suffering coworker who covers the patients when your patient must abruptly leave to fight evil. All this is true for emergency medicine docs too but I feel like the emergency room has been done a lot. The hospital is relatively unexciting. [Answer] ## Psychiatry Doctors of psychiatry have medical degrees (because they can prescribe medication). A psychiatrist can have their own private practice, which then gives them some flexibility to pick and choose their patients, which is important for your hero because psychiatric problems can indeed cause urgent, life-threatening emergencies; having a private practice will give her the ability to avoid taking on any patient whose troubles are likely to lead to that kind of emergency. Of course, a private practice doesn't have to be a one-doc affair; she and a few colleagues could form a practice together (or maybe she joins one that already exists), and she could redirect those problematic patients to her other partners. (Probably some quid-pro-quo would need to be worked out, otherwise she's just cherry-picking the pleasant cases.) Practicing psychiatry has a few semi-unique benefits, one of which is that it can technically be performed anywhere -- anywhere that the doctor and patient are both comfortable. It does not generally require specialized equipment that might tie the activity to a specific location. She may need to keep a scrip pad in her overnight/crime-fighting bag, but I think many real docs do just that. It doesn't even have to be done in-person: some patients might be satisfied with a video call, audio call, or just a text, depending on the circumstances. Your hero will have to use her best judgment, of course: just because a patient says they are willing to settle for text message, that doesn't make it true. If she is good at her day job, she'll develop a feel for this. And psychiatry really does help people. Not everybody needs a therapist, and not everybody can be helped by just a therapist, but when you need a therapist, only a therapist will do. A good shrink can save your life. --- For the author, there are some other advantages. Psychiatry went through at least one period of heightened cachet in the real world, which means your hero can be highly respected or regarded as a quack, or both! -- whatever suits your needs. If your hero gets lucky and manages to help a patient who is particularly rich or famous or influential, it could make her career. She could end up with a long waiting list of people who wish to be clients, which will allow her to be more selective and also charge more for her services. She could write a book and use the proceeds to fund her supernatural work. These developments can occur at practically any time that is convenient for your story. Psychiatry is also pretty intimate, so the social connections made with patients will be strong. Again, if any of these patients are important, they might open doors for your hero that might be impassable otherwise. "Friends in high places" is a very convenient deus ex machina. Shrinks also get to dress right instead of walking around in lab coats all day. If yours is a visual medium, this means you are not denied the use of personal wardrobe as a way to develop her character. [Answer] Unless you want them to be a surgeon constantly leaving patients on the operating room to save lives. Unless that then it's doable. But the trick is not their field of medicine but their boss. Think about it. Working for a normal hospital will seriously conflict with their life style as you figured out. But also trying to grow a personal practice, like a private clinic, would still have issues. If you are unreliable then what's the point? So. What is the solution? ## Avoid life or death fields Optometrists, dentist, otolaryngologist, dermatologist, neurologist...etc. Basically any field in which you can cancel an appointment and your patient does not just die. The patient can get their teeth cleaned later, skins conditions are not a joke but again they are not waiting for you to operate on them. Better still. Make the doctor specialize in a field in which they have to do a lot of research. Rare diseases anyone? Kinda like House. So. Your doctor can ponder over the rare condition that the patient is having while they drive to fight the monster of the week. ## Logistics It's rather simple. If you can hook them up with a sort of a connection to the underworld that can get them a job in a hospital or similar place without having them follow the rules then you know what to do. Maybe they uncovered the truth about a conspiracy against a big vampire. The vampire just happens to have good connections with a hospital, because they have to get human blood without killing people for example, and to repay them the vampire made it clear that the doctor practices medicine on their own terms. Unless they bring a machine gun and shoot people, nobody dares bother them. The same can be done with a private clinic. If they just make one with a couple of friends and possibly provide funding or other big contribution in exchange of being able to simply leave if needed. Again you can connect it to their supernatural life. Maybe they acquired a nice downtown property while they are fighting the supernatural. Then they got together with a couple of doctor friends and sat up the clinic in part of the property. Maybe it's one of those old places with like gargoyles and stuff. And if you are adamant about that life style not paying off. You can justify it by that fact that their ownership is cursed. They can't sell the property, and they can't rent it. Or they can use some sort of powerful magical item to ward off the supernatural but they can only use or afford to use it in like few floors and so the rest is not really usable. I support finding a connection to their supernatural world. But you can still solve it without that. [Answer] Kamen Rider Ex-Aid features four heroes all of whom are doctors and all of whom specialize in one area of medicine... The main character is an intern and thus changes departments (he starts as a pediatrician and is more of an appointment character), the next is a surgeon and one who is by appointment only. The third is a Corner and can excuse himself as part of investigations, the fourth is a radiologist (and additionally an unlicensed doctor at that.). It also helps that the setting is in Japan's government funded medical system, and the Ministry of Health knows about the doctor rider's superhero activities and actively supports them (the bad guys of the series are monsters that are the results of a human becoming infected by a computer virus that somehow turned into a biological virus.) so they are able to pull strings. ]
[Question] [ This question already has answers here: [How can I make a net beneficial genetic trait occur only in a small fraction of the population, sustained?](/questions/8900/how-can-i-make-a-net-beneficial-genetic-trait-occur-only-in-a-small-fraction-of) (10 answers) Closed 4 years ago. Consider a population where a low percentage of people (5%) posess a genetic advantage over the rest. In my fictional world, let’s assume this small percent of the population can wield magic while others cannot. Now over the course of millenia, the count of the advantageous group should increase due to natural selection and eliminate the larger less-advantageous group. I would like to know how this can be prevented from happening - the possible exceptions that cause this minority to still remain a minority without going extinct. Edit : * Both parts of the population - magic and non-magic users get along with each other. The normal population would probably resent the mages to a certain extent for their magical abilities but they are rather civil about it. * These mages would be functioning members of the society (scholars, apothecarists etc) and are not being persecuted by the common folk. [Answer] The actual challenge in your question isn't just to prevent the trait from spreading via natural selection - it's also to prevent the trait from going extinct via random drift. Natural selection is an important factor in evolution, but before you have natural selection you have [genetic drift](https://en.wikipedia.org/wiki/Genetic_drift) - the natural random fluctuation of how much of a gene there is in a population. Every generation, people with a certain allele have more or less children and pass on the gene to more or less of them, meaning the percentage of people in the population with this allele will go up and down semi-randomly over the generations. It so happens that mathematically, if all alleles (alternate versions of a gene) are equally likely to be passed on to the next generation, after enough generations you will get to a point where there is only one allele left. Simply because when your percentage fluctuates randomly over time, you'll eventually hit "0%" or "100%", and once you've hit either of those numbers you'll stay there (obviously if no individual in the population has an allele they can't pass it on to their offspring). This is called "fixation", when an allele reaches 100% of the population. The odds of an allele reaching fixation, in the completely random scenario, are proportional to its frequency in the population; meaning the higher the allele's percentage in the population, the higher its odds of taking over the population. Conversely, the lower its percentage, the higher its odds of going extinct. Natural selection doesn't prevent this, it just nudges the odds on whether an allele will reach fixation or go extinct. So the problem you have with your genetic magic ability is that you want your population to be a stable minority over the long term. Most of the suggestions you'll get for preventing natural selection from promoting the allele may indeed prevent the allele from becoming fixed in the population - but in doing so they'll instead guarantee the allele will go extinct over the long term. What you need is active selection pressure to keep the frequency of your allele at a low but nonzero share of the population. There are many ways of achieving this; the basic idea is to have some way in which the gene is beneficial (selected upon) if it's rare, but harmful (selected against) if it's common. The best suggestion in the answers so far is the sickle cell anaemia analogy, though they get the mechanism wrong. It's not that the sickle cell alleles protect from malaria at the expense of ill health; it's that if you have one sickle cell allele you're protected from malaria, but if you have two alleles you get sickle cell anaemia. This means that as long as the allele is rare it's going to be beneficial, because most people will get only one copy. But if it becomes too common then you're more likely to get children who have both, which is bad, which means having the allele becomes deleterious. You could get some interesting side effects if you went with this exact mechanism. If you have a gene with one allele that gives magical powers, and people who are heterozygous for it are magic users, people who are homozygous for the magic allele are reproductive dead-ends (they're sick, they're insane, they're infertile, they die in utero...), and people with any other version of the gene are nonmagical, then that means every magical family will include nonmagical members (because every magical person necessarily has a non-magical allele to pass on). You would also have negative consequences for magical people who have children with each other, which would discourage "inbreeding" within magical communities. Of course you don't need to resort to complex genetic effects like this, you could have any mechanism that depends on how many magic users there are. For example, social forces could make having magic beneficial as long as they were rare enough to pass under the radar, but if there were too many magic users the witch hunts would start (though I don't think it's that realistic to assume social forces will be constant on evolutionary timescales). Or there could be properties of magic itself - The Dark Ones seek out magic users to eat them, but only wake if there are a lot of people doing magic in the area. Or you have a tradeoff in how sensitive you are to the magical fields: if you're a little sensitive you can do cool stuff, if you're very sensitive you get incapacitating headaches, and the more people are around doing magic the stronger the magical fields become; this would mean when few people have magical powers the threshold for sensitivity is high, and any magic gene is beneficial; if many people have powers the strong magical fields mean it takes very little sensitivity to get debilitating headaches, so the magic genes become harmful, and you end up with a stable situation with a small proportion of people who have the genes, and those come in a range of sensitivities, most being average and some unlucky souls getting the headaches (and maybe those need to move away from the other magic users, living as hermits or in places magical people are rare). Note that this is all assuming alleles don't appear, which in the real world they do of course via mutation. Whether this is worth taking into account or not depends on how likely and common a given mutation is. It is perfectly reasonable to assume the magic genes are a rare mutation that happened only once or a few times, so you only get a magic gene if you inherited it. But you could tweak things a lot if your magic genes are likely to appear via random mutation; you could even go to the point, as another answer suggested, that magic users are all de novo mutations and they don't spread beyond that baseline mutation probability because they're all sterile... But at that point why have it be a genetic trait in the first place. Point being, if you allow a baseline rate of new magic mutations you have a guaranteed minimum percentage of magic people without having to worry about them becoming extinct; you also have different social dynamics with respect to whether magic is a family thing and how much of a family thing it is. ETA: I want to note one thing on the mechanism though - you don't have to worry about this if you want to be fuzzy on the whole thing, but if you want natural selection to function in a realistic way you need to keep in mind it acts on individuals. So when talking about whether the magic allele is beneficial or harmful, it isn't enough that it's beneficial or harmful to society, or to the magical community - it would need to be directly beneficial or harmful to the individual that has the allele (even more specifically, it would need to affect how many offspring and grand-offspring that individual can be expected to have). [Answer] Infertility, magic talent comes with a severe reduction in fertility if not down right sterility. Now would that not make them die out? Not of the mutation rate among regular humans is high enough. So your regular humans every now and again have a child with magical ability but it's sterile. So the child will never pass on their highly effective magical genes. [Answer] Sickle cell anaemia and malaria In a malaria-ridden country, sickle cells provide a marginal advantage to survival because they give immunity to to the disease despite causing some ill-health. The condition allows humans to reach reproductive age. In malaria-free countries sickle cell is a distinct disadvantage. A magical ability came about by a genetic mutation. Unfortunately that mutation either reduces fertility or makes for a high death rate before puberty. The following is a fairly technical explanation but easier ones can be found in more popular-type articles. > > Heterozygotes for the sickle cell gene are relatively protected > against malaria, while patients who are homozygous for the sickle cell > gene, suffer from sickle cell disease and are highly prone to the > lethal effects of malaria. > <http://www.scientificanimations.com/malaria-loses-sickle-cell-battle/> > > > [Answer] Species that are as complicated as humans typically take many millennia to evolve, but the 2 basic approaches are. Sexual Selection If you don't want a gene to reproduce, simply make it undesirable for the population to breed with those of "genetic advantage". The reasons for such could be cultural (anti-magical bigotry), biological (humans at the time see the trait for magic produces ugly people), or purely functional (maybe those with magic cause unintended spells that occasionally slay offspring). Recessive Trait Make the gene for Magic be a recessive one. In the same way that blue eyes are more rare than brown ones, magic genes may be rarer that non magic genes. [![enter image description here](https://i.stack.imgur.com/S7IhE.png)](https://i.stack.imgur.com/S7IhE.png) [Answer] Basic exceptions to this rule of nature are: * lack of competition * separation * natural disasters * Human interference Feel free not to read this explanation if you don't think you need it: If I'm not mistaken, Natural Selection is the idea that organisms which are more fit for the environment are more likely to survive than those that are not as well designed for the environment. If this is the case there are a few elements that affect this process. We can find out what these are by thinking about what can make things more fit for a certain environment, or what things create opportunity for superiority. Right off the bat, we have competition. the more things in an environment the more apparent Natural selection is. If there is very little in the way of competition many things escape natural selection. For example, a pack of wolves kills a deer, they all eat equally at first, but one day a wolf is born with a mutation in its genes that makes its teeth sharper. this wolf has a competitive edge and will tear more meat off the animal than the others because it can rip and chew faster and more effectively. Thus he would be healthier and become the alpha and have more children than the other males. Eventually this one mutation would overrun the wolf population, natural selection right? but an exception to this is lack of competition, if there is enough deer that all the wolves eat right then sharper teeth have no place in the world of natural selection, however longer or stronger legs might. Moving on to another exception to natural selection is separation. Say there are two islands with extremely similar environments, and both have wolves on them. both islands have plenty of deer so no wolves have to compete for food. however on one island the wolves have stronger legs. they catch more deer, but natural selection never takes place and both wolf races live on equally because they are separated. Yet another exception to this process is interruption by natural disasters, such as a volcano erupting. this kind of thing could kill off a developing superior mutation and completely stop Natural Selection in its tracks. Lastly, the biggest exception to Natural Selection is human interaction and interference. Every time you see a video of somebody saving an animal from an icy pond or something that is an example of humans interfering with Natural Selection. The trapped animal did something that made it fail at life, for whatever reason. This means the animal wasn't entirely ideal for the environment. As nature would have it this animal should have died. but humans don't work like that, i guess. I hope this answer was helpful and thank you for your patience in reading this. [Answer] Just make the magic gene a recessive & tie it to infertility ~ two copies of the gene (one from each parent) are needed to express magic ~ but two copies cause infertility, a mage can't have children. > > Only those with one (or no) copy of the gene can have children ~ only those with two copies will have magic. > > > Crettig's answer shows you the distribution of children from parents who each carry one copy of the gene, so any mage with three siblings will on average* have no siblings that also have magic ~ but two will be carriers with one copy of the gene & one will have no copies of the gene.* If they don't have the tech to identify who has or hasn't got the gene someone might still spot the pattern so siblings of mages from different families might be encouraged to marry each other but that's still going to be a bit hit or miss so you can still plausibly keep your mage population low. I know that's a bit short & pithy for an answer, but honestly, there's nothing more need be said. [Answer] [Frequency Dependent Selection](https://en.wikipedia.org/wiki/Frequency-dependent_selection) Imagine a trait that is advantageous to have until it reaches a certain frequency in a population, at which point its fitness decreases often leading to a stable state (i.e. 5%). A real world example of this would be camouflage coloration in lizards, insects, and fish. If there is a species of lizard that is mostly red with a few blue individuals then a predator will evolve to see and respond to eating the red ones. The blue lizards will have a higher fitness and increase in frequency until they become abundant enough for the predator to evolve a preference for them, eventually resulting in a stable frequency of red and blue lizards. This phenomenon can be seen in disease dynamics, and even antibiotic resistance! So let's assume that magic users have a high fitness but something happens if their frequency gets too high. A magic plague may only be able to spread if there is a high enough frequency of vulnerable individuals (think vaccinated children). Or perhaps an an ethereal predator can sense magic users and if the frequency of the magic user phenotype is high enough it's worth a hunting trip. These possibilities require a culling of sorts, but the principle could be extended nonviolently in a magical world! Some real world examples of this happening in humans: [Blood type frequencies](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0125003) remain surprisingly stable between populations around the world. This is most likely related to immunity and frequency dependent selection on diversity. A classic example of balancing selection in humans at the [MHC/HLA locus](http://www.genetics.org/content/104/3/449.short) also relates to frequency dependent selection on immunity. This pattern is seen in almost all life with an immune system, a disease will most likely evolved the ability to overwhelm the most common form of immunity causing the forms to increase in frequency. Even the frequency of [right vs. left handedness](https://doi.org/10.1016/j.jtbi.2004.12.021) is best modeled via frequency dependent selection! [Answer] Well there are a few ways this can be achieved. They may have worse health overall. I don't know what sort of magic your users have access to, but maybe they're more susceptable to diseases or just live shorter than magicless humans. Another angle could be to give them lower fertility that magicless humans. The magicless humans keep the population down. It's not hard to figure out that a guy who has access to magic might be a serious problem for you if he or she decides he or she doesn't like you. The solution? Ensure that there aren't enough of them to be a threat to you. [Answer] You could require a combination of genetic and environmental influences in order for a child to develop the ability to use magic. Children born with the right set of genes, but in the wrong environment, are "carriers" -- they won't be magic-users themselves, but their own children could be. If the environmental influences that trigger development are random and rare -- born under the right phase of all three moons, perhaps -- and the genes are harmless in the absence of those influences, this will keep the population of magic-users low and stable. The genes could still be selected for or against: if people actively want a chance at having magical children, for instance, they will preferentially pair with active magic-users and their near relatives. On the other hand, if the environmental influences are predictable -- every child conceived within the enchanted forest, perhaps -- and the genes are harmful in their absence, this will trigger speciating selection, and in a few hundred years you'll have Homo sapiens mundanensis living on the plains and Homo sapiens arcanus in the forest (or, in traditional high fantasy terms, humans and elves ;-) (please excuse the dog-Latin). [Answer] Borrowing ideas from chinese manwas: (immortal = magic user) * the "immortals" are usually extremely competitive and spend all their time killing each other + each other's offspring * for an immortal, all other immortals are a danger * for low-level immortals, killing each other to steal their artifacts / magic powers is common. They are also bullied by higher level immortals, for the same reasons * having a family is usually a liability = hostages, so hard to have kids * They also hold long grudges and vendettas between families That brings a very unhealthy natural selection were having the "magic" gene actually put you in a lot of trouble. [Answer] I think you are missing something important here. Humans, as compared to any other living thing on earth, actively and consciously choose whether or not to have offspring. We can see today in the richest countries that the population is on the decline. all "western" countries would loose population were it not for immigration. In general, it can be said that the more educated a woman is, the fewer offspring she will have (women are more important than men here) I guess it's fairly safe to assume that your magic-wielders are comparably well-educated. It also seems safe to assume that they know about contraception (and abortion). That said, the most likely reason for them not to out-populate the non-magic people is that they choose not to spend so much time and so many resources on child-rearing. [Answer] All the previous answers ignore one obvious reason: the dominant religion thinks that magic is sinful, and hunts and kills\* those whom it suspects of being magic users. Of course, as with the historic Christian persecution of witches, many of those executed aren't really magic users, while a lot of real magic users manage to successfully hide themselves - which gives you the opportunity for a lot of sub-plots. \Though of course this is arguably still natural selection at work. [Answer] That assumes that having superpowers actually makes you more likely to find a mate and produce viable offspring. If there's a substantial likelihood that anyone who has magic will make an entry into the Darwin Awards with ill-advised experimentation with their powers, or demons thinking that magicians are tasty the odds of a non-magical person getting grandchildren may actually be better. [Answer] Disadvantageous Selective Breeding* Inbreeding: Look at Harry Potter and their "pure bloods". Mages are only allowed to breed with full blooded mages. Or, possibly, can only breed with full blooded mages. This leads to a rather small gene pool that will tend to stagnate. Cultural selection: Magic is only allowed to be practiced by the church (or other organization). Men must become monks and women become nuns (or maybe men's guild and women's guild). The reason can be anything that isolates the male mages from the female mages. This would lead to only the occasional mage popping up from the recessive gene(s) for magic. [Answer] Perhaps the government of the society sacrifices some of them every so often in order to win the favor of the entities they serve/believe in. "Oh, but your Godliness, we've brought you a new kind of sacrifice; this one can pull quarters from behind your ears!" ]
[Question] [ Alright so in my sci-fi setting, my space faring human civilisation has a widespread procedure that allows humans a very extended time period without any sort aging or its assorted issues (weakening immune systems, organ failure, etc) and basically the body is locked into a state of eternal youth . The procedure is widely available and affordable so there’s no rich/poor divide. Now the problem is that since everyone is practically immortal and are constantly reproducing with the death rate drastically reduced (people still die from diseases and other causes). The civilisation they live in has FTL and is type 1 in the [Kardashev scale](https://en.wikipedia.org/wiki/Kardashev_scale) and approaching type 2. Note: they don’t have any mind uploading technology or the like. What methods can be used to make the population growth manageable without dystopian methods like mass sterilisation or genocide or something like China’s one child policy ? Edit: they cannot simply expand much further because most of the remaining space is inhabited other civilisation, ones who are truly type 2 civilisations and they don’t want to provoke them. Edit 2 : there’s also fertility treatments for both males and females that allow their fertility to remain constant throughout their lives (if they choose to take them ) [Answer] This idea that people with eternal youth would be constantly reproducing is not necessarily accurate; nor is the idea that producing any more than 2 children per couple going to result in population growth. Additionally, China's one child policy has had massive repercussions for the State that are only just now starting to bite. In reality, population sizes in an enlightened immortal community would tend to police itself, but let's break down why this is the case... Let's start with reproduction itself. Conceiving the child is fun; raising it for 20 years? Not so much. That's not to say that it's not a rewarding and fulfilling part of your life that you don't look back on with pride and satisfaction, it's just that raising children is hard work, especially in a developed society. It's also damned expensive in that same society. So, couples who want to raise children will raise a few children, then when those children go off and live their own lives will use their eternal youth to pursue their own interests. Best of both worlds. In today's world, juggling a family, work and personal pursuits is very hard because we have a set amount of time in which to do all these things; that means we have to do them in parallel. Often people choose what they want to do by priority, and discard the lowest priority live choices because they want to focus on what they really care about. In many cases, this means people choose NOT to have children. Of course, the other reason why some people choose to have children at a given time in their life is their biological clock. They don't know if they want to or not, but time is running out, so to speak. So they take the plunge, 'just in case'. In an immortal society, the reverse in both cases would be true. Some people would choose to have kids because they can pursue interests largely in serial rather than parallel, and devote a certain amount of time to children, after/before which they pursue other interests. There would also be less impulse choices around children as eternal youth means that there is no 'biological clock' to force a decision at some point. All that said, some people will still choose not to have children, or will be unable to have children. What that means is that those having children have to have more than 2 to maintain the population, let alone for it to grow. If only half of the population pairs up AND wants children AND can actually have them, then every breeding couple needs to produce 4 children in their lifetime to maintain the existing population size. To use China as a case study, they told every couple that could and wanted to have kids that they could only produce 1 child. What was the result? Runaway ageing population. China has a serious health and aged care issue today and it's getting acutely worse, where it's predicted that in the next 10-20 years there could be one old person in need of care for every 3 working age people in the country. That's not a healthy ratio. By comparison, the old age pension in Australia was enacted when there was 1 retiree for ~60 workers; that ratio is decreasing rapidly and as such even Australia is rethinking how we define retirement and social welfare for the elderly, not because of heartlessness, but because of sustainability. Also, your question assumes that eternal youth doesn't impact a woman's fertility or that it perfectly restores her post-natal body to its pre-natal form. Neither of these assumptions are probable. The concept of eternal youth is usually predicated on one of two approaches: 1. Slowing down metabolism and cell replication 2. Increasing the effectiveness of cell repair and replication If you consider the first approach, this means that not only is a woman's body unlikely to recover quickly or well from a pregnancy, but the release of eggs for fertilisation is also likely to be slowed. This means that women would be less fertile in direct proportionality to the increased lifespan. There is also a chance that gestation would take proportionally as long - women who now live 800 years instead of 80 might take around 8 years to bring a baby to term. It also means that women would leave children to the end of their new lifespan because of the impact it would have on their body. Option 2? Well, increased (even aggressive) cell repair may well impede the female body's ability to maintain a pregnancy as this generates many changes for the woman during the baby coming to term. It may well lead to many miscarriages and the metabolic requirements would mean a massive increase in food intake which would also put massive pressures on the body to process and supply to the baby as well as the mother. Finally, we're also assuming that children will grow and leave the nest (so to speak) at the same rate in this environment. Assume children grow and mature physically at a normal rate until they're 'given the treatment'; they'll be physically mature by 20 like normal. The problem is, they won't be financially, intellectually or even emotionally mature enough to survive in this culture by themselves. They'll be competing with people who've been productive for centuries, building wealth, experience, skills; it's unlikely they'll be leaving home for decades to come. That alone could inhibit parents from wanting even more children. Put simply, eternally young mothers would probably have a proportionally higher energy or time cost to reproduction in the first place, limiting childbearing to lifetime numbers similar to what we have now. They may well stay at home longer as well, meaning that people are less willing to take on such a commitment, and even if none of this is true, we still need a critical threshold of more than 2 children per breeding couple to replenish the ranks before we worry about runaway population growth. Even if all that fails, the best possible thing you can do to limit population increase is education and gender equality. Take a look at the birth rate statistics in developed nations where there is a high degree of education and women participating in the workforce; it's close to zero. In the case of Japan, it's actually decreasing. Australia (for instance) is growing in population ONLY because of immigration. We're not having children at the rate we used do and are barely sustaining existing population counts via that method. All things considered, while it's important to consider this issue before you release your treatment to the populace, I seriously doubt it's that big an issue for you, especially if your society promotes the value of education and equal opportunities for all. If it does, then your population is going to be too busy being great at what it does to be creating a runaway population size problem to solve. [Answer] You have FTL. Why do you need birth control? Space is huge. The majority of the population wouldn't live on Earth. Between spaceships, space stations and terraformed planets, humanity would be out exploring the stars making new homes for themselves. The only reason for birth/population control is a lack of resources/space and if you have a viable method of reaching out to the stars, you have no limit on resources. [Answer] Some great answers here – want to briefly add my two cents. The TLDR version is: make contraception the norm (free IUDs for anyone who wants them!), give women full rights over their bodies, and create a more egalitarian society where anyone can have long, successful careers in fields that interest them. It does depend on how you define 'manageable population growth,' but below are some knobs you might be able to turn without getting dystopian. Having children is both expensive and dangerous. In fact, pregnancy has always been a leading cause of death for women, especially in poor countries. Combined with the fact that infant mortality has drastically declined with advances in medicine, having a baby in well off countries has become something people do less often simply because they don't need to have 12 kids just to make sure some survive until adulthood. Moreover, with ubiquitous contraception and control over their bodies, women have more choice in when and how often they have children. In most countries these days, this leads to lower birthrates naturally. And it makes sense: if you could make an expensive, large commitment with a (relatively) high risk of death anytime in your life, would it be the first thing did? Or would you get some lower risk, lower commitment things out of the way first? Given the profound nature of bringing life into the world, and having another being completely dependent on you, wouldn't you want to take the time to make sure you're ready and able to do it right? Would you want to take this risk often, or only once or twice? As of 2015, the US birthrate has dropped to the lowest levels in decades, well below 'replacement.' With more access to the things that make that possible, I don't see any reason the downward trend wouldn't continue. Having babies is hard, but in the past, NOT having babies was even harder. Make it easy to not have babies and you're probably most of the way there (again, subject to your definition of 'manageable population growth'). [Answer] The people who transition from mortal to immortal are the ones who will make kids, but the next generation could be vastly different. Education and upbringing would change as well, there is no 'need' anymore to further the blood line, and less pressure on 'settling'. After all, we have an eternal life now. This would lead to a lot of the newer generation not making kids. Look to 20 something year olds nowadays. A lot of the people who start with kids do so because after 30 it becomes harder to do. And nearing 40 you get health complications as well. Throw in work life balance and you have a not so lenient time period in which you should have a kid if you want it to work out well. That time constraint is removed now, there is less pressure and 'drive' to make kids early. People can take their time now, settle down, find the perfect partner. The people who still make kids are no problem either. In fact, there might be a bigger issue of not having enough people rather than too many. You want to explore and expand the great human empire, and colonies are dangerous. Assuming people can still die by mines collapsing, domes breaking and such. Fatality rates will be high in new colonies, and you need fresh bodies to step in. Throw in some wars here and there and disasters and I don't think you will have much of a problem. [Answer] I love all of these answers and in wishing to add to all the answers, I think in order to keep it from being dystopian is the fact that if as a natural process, you send generation-ships to other planets to explore and to make eco-friendly colonies, then assume that there is going to be accidents and attacks from the natural wildlife and the such as there are bound to be accidents in exploring space. In an utopian society, this would make such population decrease naturally without going with dystopian measures. There is also the increases of technology that needs testers. The rush to get a new invention out would be faster and probably harder not easier as the decades. So testing some prototypes out would not always follow safety guidelines and thus accidents as well will be made there as well. Then there is the fact that there will be people that, due to being able to live forever, will create a number of lotus-eater type societies. Since time does not matter to people when they get the treatment, there will be groups of people that will not pay attention to time at all. Secluding themselves in their own cities to learn or to achieve personal enlightenment. With eternity at hand, who cares if I leave for a 500 year trip to find myself? Or if someone decides to lock themselves up in their room for a few decades, who really cares? Time in a way is very skewed for this society, what we use to keep time and what we task as important won't be for them. So the very concept of time will be slowly changed. Being considered mature at the age of 20 or 30 will seem like a far-gone idea, with people in their 50's behaving as if they were in their late teens-early 20's. To sum it all up, time and exploration of space and ideas would cull the population in a natural way without the need for brutal rules to be in place. [Answer] Why would overpopulation be an issue for a type 2 civilisation? With the resources of one moderate earth-like planet you could easily support quadrillions of people. When that's all used up, just start mining the next planet. This is all considering the population keeps growing rapidly. Why would people keep getting children? I can imagine most people would get at most 3 children, because of it taking so much time. [Answer] I think the biggest question is how fast the average couple gets children vs how fast the society expands across the stars. As the population on a planet/space station/megastructure grows it will reach a point where it starts needing to move its population outwards. With enough encouragement you can get enough population to leave, and preferably relocate an older population that has had children and has less need to have more all to one planet/station/megastructure. In the meantime, economy would need to be focused on expansion and construction to ensure enough livingspace and food for the evergrowing population. You can have ways to reduce population and its growth. For example, you can increase the time it takes for people to want children as a part of the eternal youth process/program and/or education and/or deliberate anticonception. If it takes 200 years before people want children instead of 20 to 30 you heavily decellerate growth. You can have the population make the conscious decision to have a limited healthcare so that people have a higher chance to die from accidents or diseases (but with enough care that people dont suffer too much). Then theres actively reducing the population. For example by fostering the forming of solarsystem nations that might disagree with one another and go to war. This could become a "natural" way to randomly select people to die and cull populations without it being too dystopian like a lottery or something. Other options could be designing the culture around dangerous extreme sports, hunting dangerous game with limited protection or even bloodsports with high prizes and social standing. The bloodsports dont necessarily need to be to the death, but have a relatively high chance of someone dying despite some limited precautions. [Answer] ### Taxes Currently the United States promotes children by giving tax breaks to families with children. Stop doing that. Instead, families with children have to pay extra taxes. Or even just require that they provide for the children to a certain level. For example, certain educational options must be made available to children and the parent pays (possibly over time). If a child is indigent, then the parent could be held responsible for upkeep, even after adulthood. Having children on the homeworld is risky. Much safer to have children on a colony. Colonies that are underpopulated would not have the same requirement that parents support indigent children. They don't want to discourage reproduction. ### Emigration The tax revenue can be used to encourage people to emigrate to colonies that need people. Or if that's not enough, it could be a requirement. You can have as many children as you want--if you emigrate to a place that needs population. Otherwise, you will be deported. If two parents leave, that opens up two visa slots for immigrants. If living on the homeworld is desirable, then the government might auction them. The sale price for the visa might easily be enough to buy three tickets away in case there aren't enough taxes to do so. ### No birthright citizenship In our world, you can't just deport someone for having kids. The parents are citizens and by birth the children are too. So change those laws. If people have children without government sanction, they lose their citizenship and the children never have it. This doesn't need to be a draconian policy. It's not required for armed soldiers to bust down doors in the middle of the night. It might even be common to give children visas for fifty years or so to allow them time for a decent education. The problem is not finite periods of time. The problem is eternity. Chances are that most people that want to have children will leave early in this process. By the time of the story, the only people left on Earth are those who do not want children. Everyone else already found a colony. [Answer] I think the answer is much simpler, assuming they have total control on their reproduction (simple to achieve compared to eternal youth). Raising a child is a lot of work, and thanks to eternal youth, can be delayed indefinitely without much risk. It also probably slowly became the norm. That is, if I had a life expectancy of 4 000 years, I might consider conceiving a child after 1 000 years, maybe, depending on the partner. My mother had me when she was 1 200 year old. That in itself, drastically reduce the exponential explosion. That is, while people might still make as many children in average, if they do so on much bigger time scale, you have an effective birth rate that can match the effective death rate. [Answer] Real estate prices. Unless people can afford to house their children, they'll quickly learn to use contraception to avoid having them as the price of housing will climb incredibly fast. As soon as this technology becomes remotely affordable, real estate prices will skyrocket as the number of homes vacated due to death will plummet. [Answer] ANSWER EDITED IN ACCORDANCE TO SPECIFICATIONS OF THE QUESTION Biological immortality means, at least, that no sickness can get you, since your body already is in overdrive to keep itself in the best cellular and organs' conditions. ONLY a trauma can kill you, but hey, if it's not strong enough you can recover without even antibiotics, your body will work for you, hydrate and close wounds. Other problem: Brain is not an infinite storage device and, contrarily to urban myths, it is NOT underused. At a certain point, it will begin overwriting memories. A person will not go dement like an Alzheimer's victim, it will just forget slices of life, just like we cannot remember all of our own experiences since we were babies. But no worry, informatics will remember wholesale for ya! Anyway, since we're talking about a potential, disruptive demographic explosion like there was never before (let's not forget that, just by improving our lifespan of, what, 10%? and with better tech, we've grown to *seven billion* in a very short time), the only way to avoid turning the world into a barren wasteland is to devote every iota of the global economy to building generational ships. Planetary colonies won't work: Considering the new rate the global population will be growing, there is simply no time to build stuff, say on Mars, give it time (and a lot of resources) to make it as self-sustainable as possible. Excess people must be sent away on huge spaceships to be built in orbit. If they have FTL propulsion, the Arks will have a chance to arrive to potentially inhabitable planets, but otherwise Earth just becomes a bottle that will fill rapidly to the point of explosion. Simply put, no matter of politics nor redistribution will make up for such a baby boom. Unless you either start a State-sanctioned culling, or start forcing people not to have kids. Never. Because you can't count anymore on old age to get rid of the previous generations, nor sickness. The only birth tokens avalible to women would be allowed only after there's been a death by trauma (accident, homicide, suicide, etc). In this case, women should be put in a waiting list, much like we do today with transplants, until a slot is free and then she can be artificially inseminated. Such scenario would also offer narrative opportunites for assassinations-for-hire in order to allow a couple to reproduce, for example, but it wouldn't belong to a dystopian variant. Also, unavoidably, as proven in history, the more people you pack up in a space, the more litigations you get. This could lead to a scenario not unlike John Brunner's "The Sheep Look up". [Answer] I didn't do any research on this topic but I thought about it a while, and I think that just not making kids until you are able to die or like 40 years away from death, this would probably stop the population growth especially when combined with the one child policy [Answer] People will still need to buy food (or the resources needed to make food). (Either individually, or as part of groups.) People who cannot afford to eat will be less attractive mates to people who want to have more grandchildren. And in difficult circumstances, people will starve. If your answer to this is "the government will provide a guaranteed minimum income" or "food is a human right", then eventually "the government" will run into a limit for the amount of food it can afford. (At most, a government can afford a fraction of the resources of the group of people it controls.) For examples, consider the Ukraine during the 1930s or Venezuela during the 2010s. ]
[Question] [ Condensed Magic only functions as a physical material when it is in contact with living beings. Condensed magic comes in 3 varieties, air, liquid, and solid. For example, if you spilled condensed liquid magic onto a table, it would fall through the table, then fall through the floor, and be impossible to recover. If you held it in your hand, it would behave as if it were a liquid similar to water when in contact with your skin. People can spend their magic points to create this material, and consume it later to replenish their magic point reserves. Magic points replenish on their own, but Condensed magic works like an MP Potion does in most video games. How would a society that uses condensed magic as a form of currency, reliably store these materials for transport and use, if only living matter will contain them after their initial creation? Separate storage methods for each form are acceptable, but a single method is preferable. [Answer] If the microbiome counts, then anything sufficiently filthy ought to do the trick. In this case magic would form puddles on the ground outside but just drop through a stone floor. it would also probably behave like oil on pond or puddle water. If you can make solid as well as liquid magic, then the easiest option might be to store the liquid magic in containers of solid magic resting on the ground (if microbiome counts). Hollowed out and/or deformed living trees might also be an option. For short term transportation one might cover a normal container in blood (you said living matter not living beings, right?). Metal spheres could be implanted into cattle, slaves or the mages themselves - maybe with small openings accessed via blood covered syringes. [Answer] Bags were originally made from natural materials, and that usually meant living materials. A sheep’s stomach made a good liquid-holding container. Do you mean it has to be currently still living? That raises some interesting definitions, since your skin is made from dead dried cells and you said you could pour it in your hand. So there is some flexibility and interpretation in the definition. So maybe the stomach or bladder has to be filled when it is fresh from the slaughter and the individual cells are still alive; then the liquid magic causes the container to retain its living essence as long as it remains in continuous use for this purpose. That makes them a lot like lithium batteries! In particular, you should not discharge fully but must retain a minimal charge for it to remain reusable, and if stored it will self discharge slowly over time. Another idea, which I think is less cool, is to grow a sheet of some kind of plant, fungus, mold, or bacteria biofilm. It would grow on the outside of a substrate to give it shape (e.g. an ordinary bag). It grows on the outside so it can be exposed to the needed environment; e.g. tucked into soil or exposed to light. The lining will be ignored by the liquid which passes through it, and it is the living layer which holds the contents. This makes it difficult to seal the containers, other than by simply growing the hole together. You have to cut it again to access the container. [Answer] The answer depends widely on the properties of these materials. For example, is the liquid viscous? If so, one might encase the liquid condensed magic in moss or another organism which is easily grown and which can survive for some time after being uprooted. If it is viscous enough, it won’t leak through the moss. One might use animals as carrying containers for magic, depending on the absorbitivity of the liquid magic. I could see cutting open frogs, and sewing shut liquid magic inside of them and keeping them alive. Perhaps less macabe might be very clever use of [honeypot ants](https://en.wikipedia.org/wiki/Honeypot_ant) to store the magic. Of course, currency is all about efficiency. Your currency may be in the form of bills redeemable for condensed magic, akin to how our dollar was originally redeemable in gold. This would permit banks to store their liquid magic in much larger containers (like gourds while still on the plant), while the actual transactions are done with slips of paper. [Answer] Form solid magic into wearable objects -- probably mostly bracelets, but headbands, girdles, etc would also work. Wear it or trade it to others. It might be possible to store liquid magic in an orange for a few days, or to inject some into a chicken's egg. But honestly that sounds super inconvenient compared to using the solid form. I think all but the craziest magic users stick to the solid form exclusively. (The really crazy ones might just drink or inhale it.) [Answer] seeds or nuts. coconuts, beans, or oily nuts could naturally concentrate it. carob beans were actually used as a form of measurement because they were so identical in size. you real problem is going to be counterfeiting, there will have to be some sort of non-destructive test to show the seeds contain the magic and are not grown without it. But as someone mentioned tokens of exchange and banks will be invented very quickly since a purse of any size will be very bulky and they could rot. Money was invented because the valuable things, food, were bulky and/or perishable so people put it in common storehouse for a token and people exchanged it when they needed food. this way the food stayed fresh because there was a constant in and out exchange happening. [Answer] The way you have explained tells us the condensed magic can however exist in and around air which is non organic matter . If that happens to be true we can use ionized containers which keep the desired material suspended in air for storage and transportation purposes. To avoid this costly affair however we can use leather bags (leather is manufactured out of organic animal skin). This must work if the condensed magic is said to exist even in the contact of air. [Answer] "People can spend their magic points to create this material, and consume it later" There's your answer: consume it. Or make some other person or creature under your control consume it. For solid or liquid magic, you'll get it back out of the container eventually. It may need cleaning up or filtration after storage, but that's life. Air magic is a little harder to manage in a predictable way. [Answer] i signed up just for this question, firstly since this is a magical society im going to assume that we are all able to do/make magic. So being the vain humans we are and having such power in our grasp im going to assume everyone is able to be presented and look like how they want to. Now the answer is so obvious and simple and we don't need any other plants or animals. Well the "PG" answer is we store it within ourselves, and payment can be made via a kiss. Now you know where im heading for the MA15+ answer right people? Guys can store them in you know where and ladies have their own places to store them too, and transfer of magical credit for a job well done can be given via a release of the magic to the recipient in question. now before you guys start flaming about how if we were such divine and magical creatures we wouldnt just go round giving magic in such a way let me just point out how much pornography is on the internet. thank you and goodnight [Answer] Unless magic is consciousness-based, there should be plenty of plants or other evolved organisms in the biosphere already harnessing this magimaterial. (New coined word?) Since magic specifically responds to organic material, and can be consumed by players for various uses, it seems likely that various organisms would have developed to use the mana in more specialized ways than players. How the creatures gather the mana probably depends on the world. If mana is produced automatically in small amounts by living creatures, then some options might be enormous glades covered in a single moss or fungus (a la [Pando](https://en.wikipedia.org/wiki/Clonal_colony) that maximize surface area in a distributed way. Possibly they even all funnel that mana to one central area, which is one way to explain why something exists in the wild that would need massive stores of mana to exist. Alternately, if it exists outside of the creatures, then enormous plants might form to catch it in its travels. For instance, if the mana were to travel in currents up in the sky, you could get giant floating things that, again, maximize surface area to catch as much mana as possible, and then maybe use some of it to help stay afloat. Regardless, if creatures are involved, you'd probably end up with a food chain: herbivores consuming the equivalents of photosynthetics, predators chasing down creatures with greater mana stores than them. However, going too far down that line may make the resource too mundane. Possibly, using the material requires some rare resource, or for whatever reason it can't be used to power cells -- this would make it less useful, and hence less likely to develop creatures that use it for more uses beyond what the players are using it for. Alternately, make all forms of the magimaterial extremely uncompressable: you simply can't make it denser than some arbitrary number designated as 'small'. Combined with the inefficiency of energy transfer in predation, this might well exclude from existing any more than a few 'gremlin' species that consume the magic moss species, since a creature that needs to rely entirely on mana to survive would need to be excessively large to store it. That said, that might be another idea entirely requiring worldbuilding, and in any case would provide a hard limit on how much mana the players themselves can store. Alternate, far weirder idea: The mana is itself 'alive', in a way, or can be made to be alive -- and conscious. Thus, magic from players might be fine because their will somehow makes their mana do what they want, but storing mana outside a body could require 'awakening' a different bit of mana and telling it to form a bubble around the stored mana. Again, though, that feels like it'd be pretty far rom your original idea. [Answer] Can your magic be used to create "pocket dimensions" large spaces within small object? If so you use [terraria](https://en.wikipedia.org/wiki/Terrarium) that contain full sized trees grown as living containers, large flat trays for solid ingots, cauldrons to carry liquid magic, airtight boxes that can hold a volume of gaseous magic, although realistically gaseous magic is not something I would think to see much of due to the difficulty of getting it into a storage vessel. Solid magic can be worn as jewelry etc... as well, anything that stays in contact with the user at all times will suffice. [Answer] Magical currency kittens overfeed with liquid magic which causes them to become feline rainbow unicorns. They are stored in boxes or transfered electronically via virtual catcoins exchangeable to magical kittens at nearest national bank office. ]
[Question] [ Humans are an inherently violent species. We have had more wars, battles, and arguments over the stupidest of things than I could list if I devoted my entire life to the task. Let us assume that SpaceX succeeds. Overwhelmingly. Some sort of technological breakthrough shortens travel time between Earth and Mars to a few weeks. By 2150, 25,000 people live on Mars in 5 different colonies. The colonies have formed their own governments, though they pay nice, lump sums to SpaceX in exchange for new technology. The colonies are each independent of each other and of Earth, though. Say colony X discovers a rich deposit Unobtanium. Colony Y has a need for this Unobtanium, but all attempts at negotiation have failed. The prices Colony X demands in exchange for its Unobtanium are too exorbitant. As a matter of fact, since Colony X is sooo unreasonable, Colony Y has decided to loot...err, liberate, the citizens of Colony X from its tyrannical despotic government. It must be assumed that treaties are in place preventing a single colony from legally destroying another, and that to do so is considered a war crime. To bring assault rifles and grenades against a Martian colony is a good way depressurize large parts of the colony and kill most people in it. Violence in space is dangerous, so what is the best way to be violent (best being the avenue that provides the least risk of complete or near complete annihilation). EDIT: The colonies were designed to be extremely modular. Essentially, it is comprised of many small living quarters (maybe the size of a bedroom) surrounding a central habitat (where the crops are grown, the government is located, the prominent citizens live, and where supplies are distributed from) The requirements of the war are to avoid as many unnecessary civillian casualties as possible. Anything that will wipe out an entire colony(or a majority of it) is prohibited. There are some underground complexes, but they are nowhere near large enough to shelter anymore people than 500 or so. One small addition also; humans still rely on projectile weapons, as ' "Star Wars blasters" are unrealistic for the time frame we are talking about. I am asking in general what weapons would evolve to meet the requirements set forth by the situation posed by warfare on mars. [Answer] Gas More specifically non-lethal gas. It wouldn't even be expensive in terms of manpower and risk. Simply find a way to access the air system and introduce the knockout gas of your choice. Send your marines in with masks/filters and clean up any security forces that were prepared enough to have a mask handy when the gas hits. For best effect you want a colorless/odorless gas, which you can search the web for or, considering it's the future, make up as some new advancement in chemistry. [Answer] Assault Rifles and other firearms I know it's fun to think of gas, cyber and automatic taser weapons but what about good old classic firearms? * Cheap * Likely on-hand * Easy to train/use * Won't likely cause any explosive depressurisation (this isn't Hollywood), rather small leaks if hitting weak outer walls... which would plausibly be self-healing or otherwise easy to repair. [Answer] Note: I had the [same thought as Alex S](https://worldbuilding.stackexchange.com/a/36887/18562), and so this would have been a comment on his answer, but I don't have that right yet. CYBERWARFARE. Alex has already talked about installing some sort of virus to cripple colony X's infrastructure or something else of the sort. I also thought about another type of cyber warfare- emotional warfare. 25,000 people is a super tiny population group. Assuming that Mars culture is anything like current culture today, they will want to be connected to the internet. Most of the internet (I am assuming) will involve some sort of communication with earth. Which allows colony Y many forms of attack they can make on colony X. Ransom DOS attack - If colony Y has some pretty good hackers, they could find some way for colony X to be completely cut off from earth (and the entire internet resources) or anybody else unless they do what colony Y wants. Man in the middle (MITM) attack- This one is probably orders of magnitude harder than the DOS attack, colony Y might be able to get in between colony X and earth and do changes/blocks/insert messages into their communications. Propaganda attack- This is the attack which I would see working the best. If colony X is open and free with what media its citizens are allowed to consume, this gets much easier. But unless colony X is, in fact, completely tyrannical and all-encompassing, there will be ways to hack/subvert the system to get the message to all of its people. Propaganda is what we are talking about- convince the people of colony X that colony Y is in very dire need and that they can help, but whoever governs them is wanting them to die. Or frame the leaders in such a way to stage a revolution. Get the people of colony X to do the work for you. [Answer] I have a few concerns with the premise My first concern is if Colony X has found unobtanium (I presume a very valuable resource), and enough time has passed that they are using it as a monopoly resource, they would have some form of militarization to protect it. If they believed colony Y would be able to just take them over, they probably wouldn't be attempting a monopoly. Colony X would probably have assault rifles to defend their economic boon (unless they were incredibly naive or stupid). I imagine space at this time much like the wild west, where you need to defend what you have. I also don't see how colony Y would have the economic power to overcome that advantage through militaristic means. To my answer: There was a patent that was recently accepted for a self-destructing bullet (when it goes beyond a certain range). <http://www.networkworld.com/article/3037405/hardware/army-researchers-patent-self-destructing-bullet-designed-to-save-lives.html> In 100 years, something like this could develop for use in the application you describe for an actual assault on the colony. If somehow they were absolutely not allowed assault weapons there would probably be non-lethal weapons like beanbag guns, rubber bullets, taser guns, nausea inducing strobe lights, and various gasses. I know you requested projectile weapons, but I honestly think a weaponized handheld laser will be possible within that time frame. I suppose SpaceX could control what resources were available, but with 3d printing technology going the way it is I really doubt they would have too much control over established colonies. We also need to assume that a militarization of colony Y would be fairly evident through espionage, and would give colony X a chance to prepare. In fact, given the scenario you have laid out, colony X may even find allies in the unrelated colonies (as there are treaties in place). This may not be the case if every other colony needs unobtanium too, and colony X has alienated all allies. I think the best route of attack for an economically weaker foe is guerrilla tactics. Colony Y could work to subvert the economic power of colony X by attacking shipping routes, ruining mining infrastructure, hacking of computer systems, generally being a nuisance, and working to destroy any strategic relationships that colony X has (colony X probably needs mining equipment from colony Z, so if colony Y ruins that relationship, colony X loses its ability to mine long term). [Answer] In the arena of projectile weapons, there are many options which do not risk penetrating a wall, yet have enough stopping power to incapacitate a soldier. These are generally lower power rounds with less effective range than a normal round, but ranges should be very limited in a small Martian habitat. For example, the [Glaser Safety Slug](https://en.wikipedia.org/wiki/Glaser_Safety_Slug) is a pistol or rifle bullet which fragments into [birdshot](https://en.wikipedia.org/wiki/Shotgun#Shot) at very high velocity. It will penetrate clothing and flesh, but not material much thicker than drywall or sheet metal. It was used by [US Air Marshals](https://en.wikipedia.org/wiki/Federal_Air_Marshal_Service) on airplanes to avoid decompressing the aircraft. Similarly one can use shotguns firing shot and [hollow point bullets](https://en.wikipedia.org/wiki/.357_SIG). Any projectile which spreads the impact over a wider area will have less penetrating power while still be an effective short range combat round. The downside is the reduced penetration capabilities of these rounds mean they would be ineffective against body armor. In the explosives department, traditional fragmentation grenades and anti-tank weapons would be avoided. [Concussion grenades](https://en.wikipedia.org/wiki/Hand_grenade#Concussion), which kill by explosive power alone, could be used though may result in small penetrations. [Stun grenades](https://en.wikipedia.org/wiki/Stun_grenade) and all sorts of [gas, smoke and chemical grenades](https://en.wikipedia.org/wiki/Hand_grenade#Chemical_and_gas) would also be safe. --- Small penetrations of the pressure seal would be used to the attacker's advantage. Safety would require that small punctures in the walls would not grow or result in explosive decompression (sorry Hollywood, [Mythbusters did a whole show on this](https://www.youtube.com/watch?v=Fi1_1l7M8FA)). This could be used to the attacker's advantage. If the defenders lack breathing gear, an assault team could be equipped with breathing apparatus, doesn't even have to be a full space suit. They'd deliberately make small penetrations in the outer wall to cause the pressure to drop. The defenders now must withdraw, surrender, or pass out. Once the oxygen pressure has dropped to a level sufficient to incapacitate, but not kill, the inhabitants, engineers would go in to make quick patches and repressurize the area. Medics would see to the civilians. Even if the defenders have breathing gear and large numbers of civilians, siege tactics can be applied. Surround their habitat, cut off their air and water supply, puncture their outer wall to reduce the pressure (again, low enough to make people pass out, high enough to keep them alive), and wait. Depending on how good their emergency supplies are it could be a matter of hours or days before they're forced to surrender or pass out. [Answer] ## A targeted strike by a small team of pressure suited marines armed with low-velocity projectile weapons. You want to take out the government, while leaving the colony intact. You need precise, extreme violence, close range, perfectly targeted. This means you need humans. Humans with guns. Send in a small team undercover. Perhaps they are disguised as visiting diplomats. Once inside, they give their minders the slip, and take out the supreme council. Low velocity rounds, and accurate headshots would prevent random depressurisation, but just in case, the team would be equipped with pressure suits. [Answer] After reading half-way through your question, I though, "This will be easy, just one tiny hole in the wall and ...." Then I read that you specifically exclude this. Drat. Instead we have to go for the generators (or solar panels or wind turbines or whatever they use). Leave them just enough energy for life support; not enough for lights, computers, and other amenities. Make sure they understand you won't turn the power back on until you get your unobtanium. How? You want an [EMP weapon](https://en.wikipedia.org/wiki/Electromagnetic_pulse). Not the nuclear variety, but rather something like the jamming pods on military [Electronic Warfare](https://en.wikipedia.org/wiki/Electronic-warfare_aircraft) aircraft. The weapons can be tuned/ focused to affect your adversary's ability to produce and transmit electricity. With only a little target practice, you can get it just enough to make life miserable for them, but not outright kill them. [Answer] Cyber warfare All of the colonies undoubtedly rely on computers for pretty much everything. Colony Y merely needs to find a way to cripple Colony X's infrastructure so that they are forced to agree to Colony Y's terms for survival. The best part is that this can be done in a way that hides Colony Y's guilt, making the problems seem like mere accidents. Indeed, Colony Y is the white knight. Offering a discount on Unobtanium is a small price for Colony X to pay in exchange for survival. This has actually already been done. In 2010, a computer program now known a [Stuxnet](https://en.wikipedia.org/wiki/Stuxnet) was discovered to have infected computers around the world, but particularly in Iran. Stuxnet did nothing to normal computers, but for computers connected to devices which direct the processing of nuclear material, it caused these devices to break down, halting the enrichment of Uranium. To people in these nuclear facilities, it seemed that this was an accident. But it was Stuxnet. It is suspected that Stuxnet was developed by the American and Israeli governments. This leaves the problem of how to install malware onto Colony X's computers. Surely the colony has a good firewall. Just how Stuxnet came to be installed on Iranian nuclear facility computers is unknown. But there are some ideas. In a study I saw recently (and I wish I could remember where for a reference), experimenters left a CD labeled "2013 payroll" in public locations of large companies, as though an employee from the accounting department had misplaced it. An astounding 100% of the CD's were discovered and loaded into company computers, probably by nosy employees hoping to see their coworkers' salaries. The CD could well have contained malicious software which, having been loaded directly onto a company computer by an employee, bypasses most of the company's security. Thus we see that the most vulnerable part of a computer network are the humans who use it. Through a similar nefarious scheme, I believe Colony X would beg Colony Y to buy their Unobtanium just to stay alive when their computers go nuts. [Answer] Destroy their computers (and other electronics) with EMP and trade replacements for Unobtainium? (Building the EMP generator must be "top secret" since building shielding is so much easier.) [Answer] Sabotage. Find some way to turn members of the other colony in to your secret agent. Destroy or otherwise contaminate a large portion of their spare, air supply or water supply or fuel. Try to make it as untraceable as possible so there's no actual evidence incriminating your colony. Then offer the colony your spare supplies to help them survive until the next shipment from earth. In exchange they'll give you whatever resources you want. [Answer] Since we have 5000 years of recorded history to draw from, you can expect all kinds of strange ideas being floated prior to the commencement of hostilities. However, most of the good ideas were discovered quite early, so we will see adaptations of these to reflect the Martian environment. First of all, attacking enemy logistics is going to be key. An unsupported enemy will be unable to threaten you, and have difficulty defending their own territory. Many posters have mentioned attacking enemy systems through cyberwar and disabling generators/solar farms etc. This can be extended to attacking their means of communication, both electronic (disabling or destroying comms towers, antenna farms, satellite uplinks as well as roads, rails or vehicle launch pads). The next phase will be to establish physical control over areas. Soldiers on the Martian surface will be much like modern soldiers working in the high arctic, or Finnish soldiers during the Winter War: the environment will be far more dangerous than the enemy. Anything to make it harder to operate on the surface will work to your advantage, including obstacles like minefields or wire, and covering approaches with snipers or marksmen. Finally, when it comes to entering protected areas (like the enemy colony site), engineering support will be needed. Breaching charges to get through walls, portable airlocks and air systems to fix and secure areas you now control, technical experts to secure the cybernetic systems and extend the control of the invading forces. For actual combat within the colony domes, the both sets of forces will most likely use weapons and systems which cause the minimum amount of collateral damage to the area the fighting is taking place. Soldiers will use weapons similar to 12 gauge shotguns (militarized weapons like the AA-12) and concussion grenades rather than fragmentation weapons. Going through walls will be more a case of engineers hand placing breaching charges than firing RPG like weapons to blast holes. A lot of combat will probably take place using robotic devices to scout ahead, map out weak points to be breached or even do low level tasks like sever electrical power lines and IT cables to prevent enemy forces from having any means to mount a cybernetic counter attack. (edited since the last half of the answer seems to have not uploaded). [Answer] Are you ruling out civilian casualties, or just ruling out annihilating a colony? Obvious possibilities: Tasers. Not going to destroy the city walls or cause casualties, but will disable opponents. Drawback: Only disables people for very short periods. Phasers set on stun. Okay, probably not going to happen in this time frame. Rubber bullets. Like tasers, probably not effective enough. Weapons that fire poison darts. Such weapons aren't in general use because if you want to kill somebody, a conventional gun is cheaper and more effective. But they're around. Spies use them occasionally, etc. Poison gas. Oh, like poison darts, the nature of the gas is debatable. Does it kill, incapacitate, render unconscious, etc? Any of those would work. Something that makes people too sick to fight for a few days is probably enough to let you take over the city and throw the die-hards into prison camps. But it seems to me there's a big problem with the premise: If the Rules of War in this culture rule out blowing holes in a city's pressure wall, how do the attackers get inside to use their less-destructive weapons? Couldn't the defenders of a city just close all the airlocks? Or even if the attackers can break open the airlocks, so they come through these narrow openings where the defenders can be waiting for them and pick them off one by one. I'd say the more likely scenario is: We don't try to restrict the types of weapons. Rather, we agree that all colonies are "open cities". That is, all combat is conducted out in the "wilds". If you break through the enemy armies and reach their city, the city opens its door and surrenders without a fight. The alternative is that you blow a whole in their pressure wall and they all die. Many places in history have adopted this policy to minimize civilian casualties. It works as long as both sides respect it. Which, admittedly, is an iffy thing. [Answer] Siege. Surround the city at a suitable distance, killing anyone attempting to arrive or leave the city, also preventing supplies from arriving. Depending on how unwilling the surrounded city is to surrender, this might turn out pretty violent. Because the fighting happens a good distance from the city, there is no risk of damaging the city's life support. Also if a notice is given, most civilians will stay in the city and only military will fight. [Answer] > > The unobtanium mine is only accessible from Colony X via a tunnel network, though it is actually located a fair distance away from the colony - DJMethaneMan > > > Claim jumping. Here's an old weapon that you can give a sci fi twist. You have these established colonies duking it out letting you depict the story of developed colonies. How would you like a chance to tell the story of forming a new colony? Colony X has carefully made sure to access the mine only through the exploratory underground tunnels that originally leveraged off of Colony X's life support. Who needs to live in a bubble when you can tunnel? By keeping all signs of mining off the surface not even most Colony X workers know where the mine is really located. Colony Y uses the oldest weapon, information. They develop a spy in Colony X who has some close personal tie to someone from Colony Y. The spy works to learn the location of the mine and, once that has leaked, Colony Y uses another weapon you've already mentioned, colonies. They start colony Z, right on top of the mine. [Answer] A non-lethal but highly contagious biological agent would serve you well in crippling a population. Enclosed colonies are highly susceptible to disease; if you can find a way to slip a modified flu virus past the sterilization barrier you'll be able to strike while the whole colony is too sick to resist. [Answer] You need screw drivers, wire cutters, sniper rifles, and possibly chocolate Your prospects on a direct colony assualt are poor. You have a fragile structure (as seen in earlier posts). A large civilian population dependent on the fragile structure. What's more probable close confines. Smaller habitats are preferable as their is less environment to maintain. Here's an idea: Don't fight inside the structure. Create a situation where the enemy comes to you by cutting off their atmosphere controls (hence the screw drivers and wire cutters). When the enemy soldiers come out with sniper rifles -- they are more accurate than assault rifles anyway. Play this out as long as possible. As long as they have people they need atmosphere. If you have to go in use the suggestions above, but this is a last resort. Now for the chocolate. Before you do anything infiltrate the enemy colony gather intelligence. Things like wide versus narrow corridors makes a big difference. Further we don't know if the unobtainum are sweet sweet martian cream pies or poorly contained antimatter the USS Enterprise jettisoned while waddling home. Further this espionage ring could be turned into assassination team. They could kill as many civilians as you want as long as you could blame the whole fiasco on Colony C. [Answer] If you're interested in this, read this free online novella by James S. A. Corey, a prequel to The Expanse novel series that's now a TV series: <http://www.syfy.com/theexpanse/drive/> One good insight here is that distance is measured in time. If one side of the conflict has much faster ships, that overwhelms almost all other advantages. ]
[Question] [ It is known that people, when looking at some complex patterns have the tendency to find human faces in them. My character goes to a museum exhibition of abstract art. She finds herself in front of an abstract painting, which looks like a normal abstract painting, in other words, it's nearly impossible to tell what it is about, and sees something in it, a pattern, which she believes is her image. Unknown to her, the painter knows her and she knowingly put that pattern there. The painting is too abstract for anyone else to see that same pattern, and recognize it for what it is, unless they share some characteristic with the painter and my character. The question is if this is possible in real life, and if yes, what could the people who see the pattern share to see it the same way? [Answer] Your character is a tetrachromat. Tetrachromats are 1% of the populaton, maybe. They are all women. They have 4 color channels instead of three. They can see things that ordinary people cannot. <https://www.popsci.com/article/science/woman-sees-100-times-more-colors-average-person/> > > Antico doesn’t just perceive these colors because she’s an artist who > paints in the impressionist style. She’s also a tetrachromat, which > means that she has more receptors in her eyes to absorb color. The > difference lies in Antico’s cones, structures in the eyes that are > calibrated to absorb particular wavelengths of light and transmit them > to the brain. The average person has three cones, which enables him to > see about one million colors. But Antico has four cones, so her eyes > are capable of picking up dimensions and nuances of color—an estimated > 100 million of them—that the average person cannot. “It’s shocking to > me how little color people are seeing,” she said. > > > Tetrachromats can also pick up color in low light, when the world looks black and white to the rest of us. Your artist is a tetrachromat too. Her abstract works have more dimensions than ordinary people can perceive. She knows your character can see the world as she does. She adds your characters face to one. She adds an inside joke to another one. --- Prose description of color perception is constrained by our words for color. If you go with the proposed scheme you could take a page from [synesthesia](https://www.npr.org/sections/thesalt/2013/03/12/174132392/synesthetes-really-can-taste-the-rainbow) and use adjectives from other sensory modalities. [Answer] It's totally possible. When I was still a student, I had a colleague whom I used to call with a very peculiar nickname, of a not so common fruit. If I had put that fruit in a doodle, she would have got the hint but nobody else. Same can happen with a more abstract pattern, which has some significance for both the painter and the specific viewer. [Answer] ## How abstract is that painting ? The obvious example.. Klint, Van Doesburg [![enter image description here](https://i.stack.imgur.com/bZdEn.png)](https://i.stack.imgur.com/bZdEn.png)[![enter image description here](https://i.stack.imgur.com/jk8UR.png)](https://i.stack.imgur.com/jk8UR.png) There's no face, or any other life element here. The lady probably did not recognize herself in these. Next stage below Kandinski, [![enter image description here](https://i.stack.imgur.com/Nybyh.png)](https://i.stack.imgur.com/Nybyh.png) No clear facial expression, there are some loose white triangles, suggesting eyes. Now this painting could have a name, say "angry man beating his dog" or whatever. There is a suggestion of a animal head.. lots of info, lots of things in this image.. but still, there is only geometrical shapes. Recognition would depend on a specific clue. See other answers. She recognized herself. How about Joseph Saki, two figures [![enter image description here](https://i.stack.imgur.com/Srxx3.png)](https://i.stack.imgur.com/Srxx3.png) With this one, it could be different. The long posture, the colors.. the grey lines, hair shaped.. a person could recognize certain features. .. I won't put Picasso.. his abstract portraits are obvious, the lady would recognize herself. In short: there is degrees of abstract art.. It would depend on the artwork. You present an intriguing scenario, I upvoted your question, although I think you'd need to show us the picture. And in the end.. there are only opinions about art. Maybe my answer is subjective. I can't recognize any human feature in Van Doesburg's rectangles, maybe she can ? All illustrations in this answer are from [Wikipedia - Abstract Art](https://en.wikipedia.org/wiki/Abstract_art) [Answer] She has a tattoo somewhere on her body which is not normally visible to other people. The tattoo is a unique and highly distinctive design, and it appears verbatim in the artwork. There are even other elements of the artwork which can be interpreted as the shape of a body, and the tattoo's design is correctly located relative to those. The artist could be the same person who gave her the tattoo. [Answer] I think the easiest way to explain being able to see the face in the painting is that the character had seen an earlier sketch by this same person before. Years ago, the character looked over the artist's shoulder to see them drawing something and asked what it was. The artist explained that it was an image of their face, pointing out the different contours of the painting and explaining how it looked like her. For example, seemingly random circles are the insides of her eyes. The jagged triangle shape represents a nose, and the ovals at the side represent ears. Art is subjective, so there is no one right way to interpret it. What looks like a butterfly to one person may look like a mask to another. In the same way, while most people take a look at this and see a boat, a train, or a random assortment of shapes, our main character sees a face. If she really cares about this artist, even not knowing that it was them who made the painting, seeing the same shape might bring up old memories of that one time she saw that artist sketching out a similar shape. It also might help if the character has a unique view of the world. One day, the artist could have been drawing a boat, only for your main character to exclaim "Oh look, that's my face! See, those are my ears and that's my mouth." The artist just rolls with it and laughs, redesigning it to make it look more like a face to the character. Lastly, little details would clue her in that it is not just anyone's face, but hers in particular. For example, a series of lines have the same color as her hair. A pair of circles has the same color as her eyes. A unique shape at the bottom resembles the locket she always wears. It's kind of like an inside joke. If you don't know the artist well, the details just seem randomly placed, but they have simple explanations only these two understand. [Answer] ## Her Likeness is Mirrored If you were to meet yourself in real life, would you even recognize yourself? In general, the people who see you every day would see your face and recognize you right away, however, your own face is a different. Most of us only see ourselves when we look at ourselves in the mirror, but mirrors flip what we see so that what we actually think we look like is often a mirror image of what we really look like. You see your hair parted on the left, others see it parted on the right. You see your left eye is slightly more droopy, others see the right eye is slightly more droopy. The one more extreme example of this was a model I used to work with who had crooked teeth. When her mouth was closed, you could not tell her teeth were crooked, but it distinctly changed the way she looked between when she was photographed from the left or the right to the point she could be mistaken for two different models. Human facial recognition is sensitive mirror image effects; so, if the painting is just at the edge of abstract enough to be recognizable as her, but it is mirrored, then she will be far more likely to recognize herself than people who are only used to seeing her in person. [Answer] Pareidolia. It's the reason faces appear in everything, from mountains in New Hampshire to electrical outlets. The idea of seeing your own face in an abstract painting is completely plausible, as in [this painting](https://wenaha.com/wp-content/uploads/2015/10/doolittle-theforesthaseyes.jpg?w=656) by Bev Doolittle. Despite clearly being a forest scene, there are 11 Native American faces hidden within it. This painting also shows how faces can be hidden within a painting, and if done more subtly it could have the effect you describe. It may even be easier in an abstract painting. A 'Have a Nice Day' smiley face is just two lines and an arc. Same with this one, :-) As for what they could all have in common, they could either (1) be tetrachromats or colorblind, (2) have a high IQ or similar quality, or (3) only recognize themselves (people have an easier time recognizing those that they know well, compared to a random face). [Answer] * Your viewer gets to see the painting under different lighting conditions. Maybe they’re a curator and the get to examine the painting under UV light to assess the authenticity, but it reveals a new image painted in ink that would otherwise be invisible. * Or maybe they’re a security guard and they’re there after hours when the lights are turned down and there’s a painting that glows in the dark. * Maybe the artist uses different glosses of paint, so that from a certain angle at a certain time of day a shimmer of a hidden portrait shows up. [Answer] Once she bought a particular light fixture or a chandelier in an art shop. When she was home she noticed that when only that light was switched on it projected a particular shadow on the wall. For some time she used to switch on that light only to observe that shadow with curiosity, but then she began to feel it disquieting, so she packed the light and left it in the basement. Now she saw that shadow again. Variations: a sculpture with a reflecting surface that created distorted image like curved mirrors do. A damaged webcam that created strange images she saw on her computer, but she never shared with anyone. A cracked glass in one of her home windows that created a strange reflection. ]
[Question] [ I regularly see people speaking about the difficulties of technology underwater, and see questions about whether underwater civilizations could produce [fire, electricity, etc.](https://worldbuilding.stackexchange.com/a/62623/35649). But I haven't seen any talking about what an underwater people would excel at, technologically. People in different environments sometimes developed skills and technology because of that environment, be it sailing or sword-smithing. Then, while living underwater would hamper many of your technological efforts, surely it would encourage some as well? I am using mermaids for this question, as there are too many possibilities and questions if it related to any and all underwater life. So let's stick to mermaids that can breathe underwater and above water, for simplicity. So, what sorts of technology might be accelerated or developed, due to their unique situation? [Answer] It seems quite obvious, but fish farming and fishery should be the obvious answer. We landlings have had a few thousands of years for developing domesticated animals like chicken, sheep, cow, horse and so on, which we use for getting access to meat, while we fish farming has been a rather recent exploit. For merpeople I would guess the opposite would be true: they would probably have domesticated tunas, salmons and what else, having developed domesticated breeds which can be very distant from the original, living in the wild, ancestor. [Answer] Sonics - Many aquatic mammals have complex auditory communications that can travel thousands of miles. They also have complex anatomy that enables them to send and receive these messages. Mathematics - much of human geometry is based on starting in 1 or 2 dimensions and extrapolating to 3 since we live largely on a 2d surface and our primary visual system is based on 2 dimensional grid of light - we have two eyes but they each are a 2d grid of rods/cones on the back of our retina so our brain creates some 3d information out of two 2d images, but we are still primarily thinking and experiencing life in 2d. Mermaids would have experience living in a 3 dimensional environment, more like birds than land mammals, perhaps with sonic-organs that are built to sense a 3-dimensional landscape. So perhaps they would have an easier time grasping 3 dimensional mathematics and also extrapolating it to 4 dimensions, which would help when comprehending Special and General Relativity. A good example in my opinion of this is how we tried to understand Angles in three dimensions - we simply recorded three 2-dimensional angles for each object, as if we attached 3 high-school math protractors to an object in space (roll/pitch/yaw). But this system can lead to Gimbal Lock which is an unpleasant situation where a navigation instrument gets stuck and cannot determine true orientation in 3d space. Perhaps Mermaids would have come up sooner with Quaternions which can represent 3d orientation without gimbal lock. Bubble physics - Sonoluminescence is a not-well-understood phenomenon relating to the high energy reactions created when a bubble collapses, sometimes causing the atoms involved to emit light. There is a fringe theory (with some notable frauds causing a loss of interest in the subject) that it may be possible to create nuclear fusion in this way <http://large.stanford.edu/courses/2015/ph241/chapa2/> Bioluminescence - many sea creatures are bioluminescent. Perhaps this could lead mermaids to study how light is emitted from biological chemical reactions Bio electricity - Electric eels have very strong electric fields, perhaps allowing Mermaids to study electricity without having to risk getting struck by lightning as Benjamin Franklin did. [Answer] My first thought is they would develop science in anything to do with pressure: Pipes, gasses, biology, etc., as they will be familiar with the bends and what happens when you try to take air deep underwater, and so they they'd likely make good use of buoyancy in their engineering. For example: Imagine using bags of air to hold up a heavy stone, as you shift it into place (it's still heavy, but now there's no friction with the ground). Tides would also be an educational tool in the study of pressure, and they may even be able to eventually harness these. [Answer] Skyscraper-like underwater buildings would have less logistic problems to design: If the mermaids can swim up and down, there is no need for stairs, elevators, or ladders. There is also no need for fire escapes because the risk of fire is very low. However, carving stone would be much more difficult, since hammers would be hard to use underwater. Merfolk can't build with wood, since trees don't grow underwater. Tunneling to create homes might be a good option, and it could allow quick travel through narrow bodies of land, the equivalent to bridges that humans build. The lack of fire would make it difficult to smelt metal and impossible to create a combustion engine. Wheels would not be useful for transportation underwater. The most important invention humans ever made was the spear. This original tool allowed mankind to wipe out their natural predators and rival humans alike, and encouraged the development of language. Spears would also function underwater, and would secure merfolk a place at the top of the food chain. Humans have domesticated many animals and plants through selective breeding. Merfolk could do the same with underwater plants and animals. Humans have been using diving bells to travel underwater for thousands of years. Merfolk might be able to do the reverse: Carrying buckets of water up onto land to breathe with. Humans have been extracting resources from the sea since the dawn of time. Perhaps merfolk could take resources from the surface? [Answer] Homo Atlantis A technological overview of Atlantians, also known as “mer-people” To see how mer-people behave when they are interacting with technology, we need to see that encounters with humans have rarely brought about peaceable exchange. Instead, tales of siren calls widowing brave sailors, and cruel marriage of spheres to the Krakenoid and Cthuloid beings that I dare not mention, we may not assume the Atlantians had similar motives nor devices to us. This means that they cannot be thought of as joyful Ariels communicating with crustaceans and woeful Danish royalty. These beings live at the extreme pressures of the oceans, as numerous surveys and repeated trawling of the seabed have not yielded as much as a clam bikini. A much more terrible Reality dawns before us, whence the motives of survival trump every other concern. During a productive stay in the realms of Atlantis, one might expect to find out how the Atlantians have solved the many challenges of life at the extremes. Unlike Man, Atlantians have no borders, and may travel freely across the planet at will using their own bodies, albeit at low speed. To compensate for these limits, Atlantian ships are designed to resemble sea beasts, and follow the basic flow of sea currents. To accelerate, complex advancements in bubble cavitation and multiple oscillating thruster scilia, get around the factor traditionally thought of as “resistance”. Much like the proposed Alcubierre hyperdrive would create a “bubble”, and using the same principle as that rescuing human Olympic divers from death when they plummet from incredible heights, disturbing the “surface” of the water, where it interfaces with the ship itself, means the resistance of water associated with surface tension, lessens remarkably. Bellows within the frame of the vessel perform peristalsis, pumping the ship through the oceans with shocking speed and unimaginable stealth to human means of detection. The combination of borderlessness and rapid transport, means diplomacy is one of the most advanced technologies of Atlantis. The rapid declaration of an individual’s intent, needs and capacity when facing a stranger or opposing force has evolved into an art form, represented by marvellous bioluminescent displays and extremely complex scent patterns, each of which is shrouded in local cultural history and mystique too dense for this limited format. To humans, atlantian encounters are life-changing events, because of the extreme difficulties caused by a complete lack of lingua Franca. Between each other, Atlantians maintain strict social order and occasionally travel in pods, like cetaceans. Chemistry and metallurgy are also specialties of the Atlantians. The presence of black smoker type oubierres into the Earths core, have spurred this development for millennia before the first human dried and burned peat, and discovered bloom in the ashes. Before the last ice age, approximately BCE15K Atlantians had already perfected complex alloys with exotic materials like manganese, molybdenum and chrome. This allowed them unimaginable advances in digging and burrowing, as the new materials could withstand heat better, and have cooling fluids pumped through the drill heads. Forging is done by the aforementioned cavitation-technology, where repeated pulses of energy cause the material to heat up and deform. Within the burrowed and accidentally evacuated cavities of the Earth, the Atlantians discovered how to travel in extreme pressure dry environments. With mastery of both the dry and the wet, the Atlantians developed rapidly within the newly excavated, vast spaces below the seabed, and gradually developed towards independence from the surface oceans, in areas where the ice covered the northern hemisphere of Earth. [Answer] Mermaids would have an intuitive understanding of water currents, convection, and quite possibly sea life. Natural human curiosity and observation will likely lead to many animal-inspired technologies, selective breeding, and quite possibly pressure-related technology. For example, an octopi's water jets (they use water for propulsion) could inspire pumps. Pufferfish could inspire something akin to our airbags. They could possibly discover metalworking, as ancient humans relied on 'native metals,' those that could be found in a relatively pure state: gold, silver, copper, tin, lead, and iron. If those can be found in such a state on land, then they might be found in that form underwater. And some of those metals (gold and lead, perhaps others) are easily worked, though that makes them bad for sturdy construction. Until then, merpeople will be relying on stone (most likely fragments), coral, and animals/animal parts as weapons. Fire urchins could be flung (using seaweed slings) or swung (using seaweed rope tied, perhaps tightened, very carefully around the urchin). Octopus beaks, shark teeth, sharpened fishbones, and the like could work very well as weapons. Since you specified mermaids, though, I see trouble on the horizon. That means they're all female, and to put it bluntly, women aren't natural fighters like men. Yes, they have a 'mama bear' instinct, but most women aren't fighters. It's perfectly feasible that your mermaids end up extremely primitive because: A) since they will likely be peaceful and avoid conflict (no need to make weapons if you don't want them or plan to use them) and B) Why build? Fish (and quite possibly mermaids, by extension) hide within, around, or underneath natural environmental structures (kelp forests, caves, coral reefs) and if shelter is relatively easy to come by, why would they develop engineering? Granted, rudimentary structures, like driftwood huts, are a possibility. But there's a good chance that they'll be nomadic. Think about it; do you see regular fish staying put in one area, or do you see them roaming about? C) No reason they'd have fire. Fire was important to human development, and since these mermaids will usually be underwater where fire doesn't exist (except, y'know, with underwater volcanoes) they'll avoid and fear fire, and intense heat in general. This seems an awful obstacle here, but hey! They'll be able to form gold jewelry, since it's so dang soft! (Seriously, it's the most malleable metal known to man.) Finally, if these mermaids are anything like the stereotypical girl, they'll spend an awful lot of their time primping. However, primping serves one purpose; courtship display, really. This would explain why mermaids supposedly spend so much time singing or lounging about on rocks; they're trying to get a man! Since they're an all-female species, their survival literally depends on their success, and so technological advancement will likely be focused on cosmetics and flirting technigues. ]
[Question] [ # Plot Noah's Flood actually happened more or less as written. Suddenly appearing flood waters covered the Earth, excepting a few mountain tops, and all land animals had to wait it out on an Ark. The flood waters receded, a few generations of thousand-year-old patriarchs went by, and then History picks up where we know it with city states rising in the Mesopotamian flood plain. # Assumptions * The waters appeared by divine intervention. * Due to the same divine intervention that caused the Flood, the land plants and animals from the ark were distributed over the world so that the flora and fauna of the planet are identical to what they truly were for all times since 4000 BC. * The Flood happened around 6000 BC. * The waters were removed as mysteriously as they appeared. The planet has the same amount of water as Earth does today. * Shem, Ham, and Jepheth were evidently adopted, since they (and their wives) had sufficient genetic diversity to explain the wide variety of humans populating the Earth. Same goes with other animals. * With the exception of the divine interventions described above, the laws of the universe have otherwise applied to Earth both before (i.e. formation of the planet, development of life, dinosaurs, Ice Ages, etc) and after (all written history) the Flood. # Question What is the first time in history that scientists could conclusively 'prove' that there had been a worldwide Flood? What would be the evidence that would lead them to this conclusion? [Answer] Science doesn't really "prove" anything beyond a shadow of a doubt. It does, however, find different things that confirm that same hypothesis, each one contributing to making it far more certain than it was before, without ever reaching 100%. --- * Myths. We'd probably have consistent flood stories from Peru to Siberia, rather than just from the Hebrews, Babylonians, and a few other Mediterranean cultures. That would hardly be proof, but it would need explaining—and would mean that every culture is looking to prove the story, not just the Christians. * Classical natural philosophy. The flood would presumably leave a massive layer of caked mud, which would be noticeable in some areas even to classical civilizations like the Greeks and the Han-dynasty Chinese. The flood wouldn't be the only explanation, but it would be a good one. * Geology: Late 18th century. Some of the first evidence that the Earth must be much older than 6000 years old came from James Hutton and his successors studying undersea sedimentation and mountain erosion. In your world, they would have gotten completely different results, which showed that the Earth's surface really was around 8000 years old. + What would be missing is evidence that a much-older Earth was blasted by a flood 8000 years ago; it would be just as plausible that the Earth only formed a bit over 8000 years ago in the first place, if it weren't for the flood myth traditions. Geology probably couldn't add much to this until plate tectonics (validated by seafloor spreading measurements) in the 1950s. * Dendrochronology: early 19th century. We'd found trees older than 6000 BC—in your world, they'd only find more and more trees that were just about as old as 6000 BC. + By the late 19th century, they'd have discovered ancient trees that all seemed to have died out before any of those trees sprouted. * Paleontology: late 19th century. It would very quickly become obvious that there are two completely different kinds of fossil deposits—the ones that are sorted as in our world, and the ones that are flood-sorted. * Zoology: late 19th century. Evolution goes back to Anaximander, but what was missing was a plausible mechanism for it: natural selection. In your world, there's a second huge question. Huxley promotes the idea that Darwin's finches prove that most speciation happened post-Flood (even though Darwin himself was not sure)—which certainly makes the Ark more manageable. But followers of Wallace argue that most species were already differentiated 8000 years ago. The answer (whichever is true in your world) would probably be strong evidence for the Flood, but we'd probably have to wait for the modern synthesis half a century later, if not even later, to find it. Until then, the evidence from biology might be too confusing to be dramatically convincing. + On the other hand… species are divided the same way as in our world—e.g., the only marsupials are the Australian families and the American opossums. How did that happen? We know from outside that the answer is divine intervention, but in-universe, do zoologists have a plausible explanation? If so, it would surely be based on Flood biology, and might be a good argument for the Flood, even though it's wrong (and discarded a century later). * Archeology: early 20th century. I believe the first consensus for ruins over 8000 years old was in the 1930s, so it probably would be around the same time that your world first came to a consensus that the oldest ruins aren't that old. Plus, it should become obvious that the oldest ruins are all in Turkey, and it took centuries for civilization to spread out from there. * Anthropology: early 20th century. Even your world's Australian aboriginal languages are probably as closely related to some continental language as French is to Hindi, instead of being isolated for many millennia. Ideas like Nostratic or even Proto-World wouldn't be minority hypotheses pushing on crank status, but as solidly confirmed as the Indo-European hypothesis is in our world. * Radioisotope dating: mid 20th century. The 1940s would be the first serious nail in the coffin. Within a relatively short span, we were able to confirm (and correct) the dating done by dendrochronologists and archeologists, and we soon came up with other radioisotopes that did the same for geologists and paleontologists. In your world, all of the thick mud deposits are the same age, all of the ancient trees died shortly before that, all of the newer oldest trees were born shortly after that, the oldest ruins in Turkey date from shortly after that, the oldest ruins elsewhere in the world spread at a plausible rate for a neolithic expansion, the flood-style fossils are all the same age, the non-flood-style fossils are spread from 8000 years ago to millions of years ago, and so on… * Molecular biology: late 20th century. A further nail in the coffin. Every land species had a bottleneck at the same time, nearly 8000 years ago. (The MRCA might not be exactly 8000 years ago—you mentioned Noah's sons all being adopted—but that's still a bottleneck of at most 3 male humans, 7 males of all kosher species, and 2 males of everything else, and the same for the females…) --- Different scientific fields tend to resist answers that come from other fields. It's not that hard to imagine that anthropologists are still insisting there must be 9000-year-old cultures long after the mainstream geological consensus is 8000 for years, only finally bending when the linguistic or archeological evidence comes in. And consensus usually takes a generation to shift within each field. It's not that common that some new evidence makes some popular theory just so obviously wrong that everyone abandons it. But I think most scientists would consider the flood the most likely theory all the way back to the early days of science, and consider it one of the most solid theories around by the end of the 1940s. --- Of course you'd still have people who don't believe, even a few with PhDs. In fact, they'd be pretty much the same people who run places like Answers in Genesis in our world. Kelly, Darby, and Scofield in the late 19th and early 20th century would have laid the same groundwork for fundamentalist anti-science they did in our world. They certainly wouldn't accept the growing scientific consensus of a flood 8000 years ago—that's before the world was even created, according to their reading of the Bible—as any reason to change their beliefs. And the reason people follow them today isn't because the Scofield Reference Bible is scientifically convincing, it's because they don't want to believe what science is telling them. Creation science would have different details from today, but would be effectively the same effort, with the same effect. --- To follow an idea brought up by Matthew in the comments: Even after most scientists are convinced that the Flood happened, that doesn't at all mean they're convinced that it's evidence for divine intervention. It might not be until the late 20th century that all of the natural explanations for the Flood turn out to be untenable. As Lemaître said, arguing for the necessary of methodological naturalism among the faithful in science, once you answer a single question with "miracle", how do you ever answer anything else? Meanwhile, none of the world's religious texts are right about the facts—the Torah is off by millennia, the Gathas are off by thousands of kilometers, etc.—so why should they be accepted as explanations of the why? (And I doubt syncretism would be much more appealing than it is in our world, so that doesn't solve the problem either.) If you want to write a philosophical story, these issues could be the centerpiece; if you don't, but you're setting it anywhere near today, science and religion in crisis is probably still a major part of the backdrop. [Answer] # With the advent of genetic engineering First a bit of background... ## Two of each "kind" Young Earth Creationists concede that — no — Noah did not bring two of each species because it is simply not physically possible to squeeze that many animals into a ship of the dimensions given in the bible. Instead Noah brought two of each "kind", where a "kind" is a very subjective type of classification. But this is besides the point... The point is that a lot of species gets wiped out in the flood... it is a mass-extinction event. This forms the basis of the rest of the answer... ## Two common ancestors These passages: > > Suddenly appearing flood waters covered the Earth, excepting a few mountain tops.. > > > ...and... > > Due to the same divine intervention that caused the Flood, the land plants and animals from the ark were distributed over the world so that the flora and fauna of the planet are identical to what they truly were for all times since 4000 BC. > > > ...means that there is no geological evidence at all of the event. [None. At. All](https://tvtropes.org/pmwiki/pmwiki.php/Main/PunctuatedForEmphasis). The "only" thing God did was to kill off all land-based animals and all humans — except for the Ark passengers — and then nothing more. So what can we look to instead? Since the genetic record is our best evidence of evolution from a common ancestor, it would be that for your alternate world too. Since all the "kinds" of animals that were wiped and reset, they have become new roots of the genetic family trees. Every "kind" of animal will have a second [common ancestor](https://en.wikipedia.org/wiki/Common_descent), and this will be very clearly shown in the genetic record. The really striking part though is that aquatic life will not have two common ancestors... they will only have one. This is where the big head-scratching will take place and that can lead scientists onto the path to discover that there was a very recent "pruning" of the genetic family free. # Odd fossil record A secondary source of head-scratching will be the fossil record. If we assume that everything else proceeded normally, with the Big Bang 13 billion years ago, the Earth formed 4.5 billion years ago, bio-genesis, common ancestry, evolution... and then \* splash \* every living animal except two of each "kind" gets wiped, then the fossil record would look extremely strange, with lots of species that should be around, but that are not. And the big give-away would be that radiometric dating places the youngest individuals of each of these extinct species at exactly the same time, to within a century's precision. [Answer] Molecular Biology would be able to find that there was a genetic 'bottle neck', as only 6000 years ago the members of all land-based species can be traced back to only 4-8 ancestors which would gravely reduce the genetic variety observed in almost any species. The genetic differences within the species would be far smaller than between species compared to today and allow to trace back their ancestry to a very small number of individuals which would lead to the idea of a natural or supernatural catastrophe which reduced the number of members of all known species so drastically that 6000 years are not eneough to recover from such mass extinction. As @Thorne pinted out already, marine life would be affected most drastically by mass extinction and one could wonder why hardly any life can be found in oceans, rivers and lakes while fossily dating beack to only several thousand years ago point towards a plethora of former marine species. These species would be completely removed from the genetic pool, but if genetic substance could be recovered from bone marrow, their relation to existing species and larger variation could be proven. Likely, nothing larger than microorganisms and algae would live in the water and these would be the only organisms resilient enough to the mass extinction to still have a large genetic variety making people wonder why higher developed species do not have it, yet used to have it in the past as fossils show. [Answer] Most marine life dies. Mass extinction event. Suddenly all aquatic life is living in a [low salinity](https://animals.mom.me/effects-low-salinity-levels-fish-11549.html) water due to dilution. This will kill almost all fresh and salt water species. As with all mass extinctions, you would have a layer of dead animals. What would be weird is the mix of aquatic and land species in the same area and layer and this layer is found globally. [Answer] Geological/Geochemical/Biological: Ice core data shows annual data going back 800,000 years. A global flood covering the entire planet would be somewhat noticeable in the data. Not to mention the small issue that ice floats. If you say the flood covered all but a few mountain tops, let's say it was 5000 meters of water over current sea level (which would leave a lot of mountains still exposed, and a large chunk of the Tibetan Plateau). This would cause the entire Greenland ice sheet to lift and break up, and after only 8000 years it wouldn't have reformed. Pretty much all of Antarctica's ice would likewise have disappeared. Aside from the worldwide effects on climate those would cause, people would be able to calculate that the ice caps were only a few thousand years old. Fully anchored dendrochronology goes back 12,000 years or so: on this world, it would get cut off at 8000. Moreover, it would show that everything only started growing 8000 years ago. [Answer] That's not how science works. Science does not prove things in a sudden and definitive way. What science does is providing us models to understand things. As technology improves and the sum of all scientific knowledge increases, those models become ever more accurate. For example, when Erastothenes first considered the curvature of the Earth, he proposed a spherical Earth model. His experiment was kinda limited, though - he only measured the curvature between two cities in Egypt. The curvature could be just local, or the Earth could be a dome, so his model was up to honest debate until Magellan circumvented the Earth some seventeen centuries later. So is the Earth spherical, like every learned person knew to be a fact from Ery to our high school teachers? No, but Ery's model was close. Earth is a tad less curved on the poles, and the curvature varies a little in some places, and then there are tides on the larger oceans, so she's somewhat between a soccer ball that was stomped beyond shape and a very round pear. On the other hand, sometimes the stuff of legends turns out to be true and makes it into Linnaeus's classification. Case in point: the once mythological Kraken now has a place in biology papers as Architeuthis dux. --- Back to your world. If the flood happened, it would always be part of scholar knowledge as historical fact. Archeological finds, carbon 14 dating and genetic analysis (we would be able to extract some well preserved genes from dinos if they had died only 6,000 years ago) would increase the model's accuracy to the point where we could probably know the exact dates of the flood start and end with a one month margin of error. But that would only be strengthening a model that was there before the scientific method was created. The flood would already be a scientifical fact when people start using the word science. [Answer] > > What is the first time in history that scientists could conclusively 'prove' that there had been a worldwide Flood? > > > Given how much debate there is between uniformitarians on the one hand, who are absolutely convinced that the flood (and Biblical creation) are a load of , on the one hand, and YEC's who think uniformitarians are full of on the other, "proof" is probably asking for a bit much. If you're going to meaningfully answer this question, I think you have to address the underlying philosophy. If whatever group is considered "scientists" in your story is receptive to the possibility of limited divine intervention, they probably consider the flood as "proven" already, and have for a very long time. If they axiomatically reject the possibility of "miracles", as does the current "scientific" establishment, then evidence of a flood won't be convincing. In this case, the only possible "proof" would be something that cannot possibly be explained as other than a divine act, and even that is dubious at best. Similarly, if for some reason, "the scientific establishment" either undergoes an internal philosophical change toward greater willingness to accept divine explanations, or externally, the "scientific" establishment (now hopefully you'll see why I've been using quotes) is replaced by a different group that already has such a philosophy, then you're probably looking at a situation in which the new "scientific" community asserts that the flood has been "proven" (to the extent that is possible for science; see other answers) all along. Bear in mind, however, that any such philosophical shift is unlikely to stop with just "the flood". In short... my advice is to do your research and recognize that acceptance of "the flood", especially if your premise is that there is "scientific" acceptance of an event that is acknowledged as "divine" in nature, is going to cause and/or require a fundamental shift on the philosophy that underlies what is considered as "science", which in turn is likely to cause a radical shift in all "historic" sciences. Specifically, once your world "allows a divine foot in the door", it's going to be very, very hard for them to continue to accept the rest of the uniformitarian package and not switch wholesale to a YEC package. At the very least, the YEC's in your universe are going to be a lot more vocal and harder to ignore and marginalize. Now... having said that, there's another point in your assumptions that should be addressed: > > Shem, Ham, and Jepheth were evidently adopted, since they (and their wives) had sufficient genetic diversity to explain the wide variety of humans populating the Earth. Same goes with other animals. > > > According to YEC's, genetic diversity is decreasing (entropy). Shem, Ham and Jepheth don't need to be adopted; they would have had greater genetic potential than modern humans. The same goes with animals. Also: > > Instead Noah brought two of each "kind", where a "kind" is a very subjective type of classification. > > > This is inaccurate. The definition of "kind" is essentially what we consider "species" today, except that speciation is occurring due to the aforementioned genetic degradation. Specifically, it deals with "genetic compatibility" and the ability to breed. While it may be difficult to determine if two modern "species" would have been the same "kind" at the time of the flood, the actual definition of "kind" is not subjective. For example, dogs, wolves, coyotes, and so forth are all the same "kind" (and indeed are still capable of limited interbreeding). Lions and tigers are the same "kind" (they can still reproduce with each other today, although the offspring are usually not fertile). Probably there was one pair of "dogs" on the ark, one or two pairs of "cats" (great cats and lesser cats may be different "kinds"), probably only a handful of pairs of creatures that eventually became the entire assortment of ruminants, and so on. (Note: I'm not counting that "clean" animals had additional "examples" on the ark.) Each of these would have had the genes to eventually become all of the "separate" species we know today; "genetic diversity" would not have been an issue. [Answer] You can never conclusively prove that any historical incident of divine intervention actually happened. Because if divine intervention could cause a historical flood, it could equally well have created the entire universe ten minutes ago along with all our memories, historical records, evidence of a flood, and so on. If divine intervention can happen, then we can’t be certain of anything. [Answer] Lots of geologists tried to prove, or ended up giving fuel to the theory of the great biblical flood using science, notable ones are Abraham Gottlob Werner (1749-1817) with his neptunism theory, and Georges Cuvier (1769-1832) with the catastrophism theory. In fact, since pre-Christian times there were those that studied fossils, and using marine animal fossils found on surface theorized that in the past a great flood had happened. The great flood myth is not something only the Christians believed, the Norse, the Chinese, the Hindu, the Greek and mainly the Mesopotamian had that believe too, so there were those seeking evidence since the birth of civilization. The theory was discredited more or less between the mid 18th and the mid 19th centuries by counter theories to the catastrophism and neptunism, like the plutonism, so I think that time would be appropriate for science to prove the flood myth considering there would be no evidence against those theories. [Answer] # Any time you like Some ambiguously defined flood happened, and then God cleaned up in some narratively convenient way. So, scientists can discover it whenever suits the story, or never at all. *Note:* I wrote up a ton of examples, but many of them ended up being about various types of extinctions, mummies, post-flood disasters, etc.. Kinda morbid, so a lot got deleted. I figure that, if it's to be a story about God from the Bible, it should probably be more up-lifting. ### Example: Scientists never discover the truth God cleaned up everything and fixed all evidence. Even if time travel is later invented, God will redirect time travelers to a fake timeline in which the flood never happened. So, scientists never discover Noah's flood. ### Example: Scientists discover instantly God directed the waters to etch the message > > God was here. > > > in the side of every mountain, in divinely beautiful writing. Intense lightning bolts struck these locations so powerfully that they altered the stone itself, causing it to glow in a beautiful display. Beneath each signature, God has written descriptions of precisely what happened in every major language mankind will use for the next 10,000 years, ensuring that everyone in the world is crystal-clear on every detail. ### Example: Upon alien contact At the time of the flood, some aliens were orbiting the Earth. They actually went down and surfed some of the waves! Whenever you like, the aliens came down to tell humans what happened. They recorded the whole thing in perfect detail across the entire world in their awesome 3D-recording technology, but they only tell humans whatever's narratively convenient for the humans to know. Since aliens can come down and show humans what happened at any point in history, you can pick when it happens. ### Example: Never, because Earth blew up God thought that it'd be funny to remove the flood waters with a second, identical flood – only this time the water was anti-matter. ### Example: Whenever they examine the salt layer The flood waters mixed with the ocean, allowing much of the salt to rise above land. When God removed the flood waters, the salt remained, coming down like a rain all across the Earth. Depending on how you pick the details of what happened, this can have different sorts of effects that can lead to discovery at different times. Or, you could have God put the salt back into the oceans, restoring their prior salinity and avoiding a salt layer on Earth, if that's better for the story. ### Example: Whenever scientists explain the platypus Biologists are stumped; it seems that the [platypus](https://en.wikipedia.org/wiki/Platypus) doesn't exist in the fossil record before the flood! Turns out these cute little creatures very closely resemble a duck/beaver hybrid: $\hspace{150px}$[![](https://i.stack.imgur.com/3yV35.jpg)](https://en.wikipedia.org/wiki/File:Wild_Platypus_4.jpg). Upon exploring their genetic history, it looks like they were sudden created around the time of the God. Behind the scenes, it turns out that God thought it'd be funny to create a new, cute-looking animal when teleporting the animals back after the flood, hence platypi! The divine spark of their recent emergence helps to explain why [some platypi secretly have human-like intelligence](https://en.wikipedia.org/wiki/Perry_the_Platypus), as behavioral scientists discover whenever. $\hspace{150px}$[![](https://i.stack.imgur.com/TSf1I.png)](https://en.wikipedia.org/wiki/File:Perry_the_Platypus.png). Maybe the scientist who discovers the truth is themself a platypus? [Answer] Assorted "experts" have given a flood date of about 2300 BC, based on Biblical dating. So, what does that mean? Just to pick one example, where the scientists are archeologists: there's no continuity in Egyptian history. There's very little evidence of the Early Dynastic Period (3150 BCE - 2686 BCE) and most of the Old Kingdom (2686 BCE - 2181 BCE) because it's been swept away or buried in sediment (needless to say, the tombs are probably full of water-born sediment) and there's a long gap where nothing is going on in Egypt simply because there aren't enough humans on Earth to do so. And the odds that anyone still uses the Egyptian language? Probably pretty low, so you're looking at a massive cultural discontinuity. Same thing in Mesopotamia. There's no Akkadian Empire. And China, and India, and the Americas, and Europe, and Africa...any existing cultures are wiped out and new cultures only arise sometime after 2000 BCE that show no continuity with previous cultures but have more in common with Middle Eastern culture (because, after all, that's where the survivors came from). Now biologists get into the act: remains from areas outside the Middle East show very different genetics from the people who were there before. Everyone after a certain date carry markers only previously found in Mesopotamia. *EDIT* Missed the 6000 BCE date in the question. Taking that into account, Archeological evidence is moved back, but it still shows discontinuities, albeit not as pronounced. The genetic evidence still stands, however. There is a massive discontinuity in genetics, and genetic data will show a huge bottleneck in human populations at the time. [Answer] > > What is the first time in history that scientists could conclusively 'prove' that there had been a worldwide Flood? > > > Since "science" has only existed for 200ish years, it can't be any older than the early 19th century. > > What would be the evidence that would lead them to this conclusion? > > > A huge layer of mud would have been noticed as soon as the waters receded. Noah and his family would would have planted their crops in it. If the Flood were actually forgotten, then "Moderns" even in Ancient Greece would have noticed the thick layer of mud. EDIT for clarification: The Ancient Greeks would have notice a thick layer of dried mud layered in the eroded sides of hills. "Science" would confirm and date it just like they dated and confirmed the age of the K–Pg (formerly K-T) boundary. [![enter image description here](https://i.stack.imgur.com/l2uFm.jpg)](https://i.stack.imgur.com/l2uFm.jpg) [Answer] Scientists may or may be able to prove the flood and a date is hard to estimate (and I will try) however the water itself is of little significance. Considering the story itself there are a few things to assume with it. 1. The water is in someway distributed so that marine life currently living does not go extinct. This is easily explained by half the Earth having salt water and the other half having fresh water so that enough room is present for members of every marine species can cram together and survive. 2. There are large geological disturbances under the water. It is described that some event along the lines of mountains being lifted and dropped onto the submerged land occurs and that the ground burst open and cracked apart. Sediment mud and other things could potentially be obscured by this. It is also feasible that dropping a mountain onto a herd of animals or a forest might accelerate the time span for fossil fuel formation. So that could be a point of observance. Depending on the story this event is set in one could also say this event is the exact moment Pangaea split (although in a much faster and more violent manner than history suggests). One might also find fossil layers that don't make sense unless a literal chunk of land fell onto another spot such as a fossil layer implying a forest became a desert that became a swamp that became a lake in under a decade. That situation would make more sense if each one got smashed onto the other in succession. 3. Man survived along with the animals. Id say man would probably have supporting evidence in our time if it occurred but I would also say that such evidence might not be obvious as supporting a flood. one person might say a glacier carved out a mountain. Another might say a giant mass of water with the weight of a glacier carved out that mountain and then froze as it receded. These issues mean that a realistic flood "proof" may not exist in such a story. Attempting to prove a metric for measuring how fast fossil fuel samples formed and under what pressure would be helpful here. Id say it would be near proven by the end of this world's equivalent of the 21st century. ]
[Question] [ So, the characters in my story are trapped in an abandoned city in a glass dome at the bottom of the ocean that has suffered damage from some sort of bombardment. I'm currently trying to work out the lore and history of that city (and the oceanic kingdom it is a part of), and, in specific, how exactly that damage occurred. I know that it resulted from a civil war between the denizens of the underwater cities and the denizens of the cities floating on the ocean's surface, but I haven't decided exactly what weapons the surface dweller used. Now, obviously, however the conflict played out, the dome remained intact, so the surface dwellers must either have launched their attacks from within the dome, or had weapons that could pass through the dome. It's a world with magic in it, so I could just come up with some sort of magical weapon that fits the parameters I want if I have to, but I did get to wondering if lasers, being light-based weapons, could pass through glass without harming it. If so, could that, potentially, be applied to sci-fi laser cannons capable of creating the kind of destruction I'm describing? Would it be believable? I did a little bit of googling on the topic, but the answers I was finding were more confusing than helpful. I often have a hard time grasping concepts unless they are directly explained to me, so if anyone has any insight on the matter, I would be very appreciative. [Answer] I have been working with lasers since my master thesis: laser can pass through glass without being attenuated in an appreciable way, mostly depending on its wavelength. For example when I worked with a Nd:YAG laser, the base frequency in the infrared and the doubled frequency in the green could easily pass through the borosilicate glass I used as substrate, while if I aimed at using the UV part, I needed to switch to quartz substrates, which were more transparent. The only thing you need to keep in mind is that the glass has to be clean and cooled. Clean because else any impurity will start absorbing the laser, heating up the glass and resulting in its breakage. In particular with weapon grade lasers. And cooled because, if it absorbs a 0.x % of the inpinging light, it will be a 0.x% of several kW, which will lead to heating up. [Answer] Yes, in principle. Although the glass in the dome will act as a lens, making it harder to focus the laser light. Also lasers are also not that great a weapon of mass destruction. If you have enough energy to do damage to something on the other side of the dome you may heat or weaken the glass. Rather than thinking about a beam of constant diameter, you could have the beam wider at the glass, and focused to a spot where you want the damage to occur. This would be hard to do in practice, but if you knew the details of the dome etc, it could be figured out. Some other things that might not matter to your story but might be something to think about: Lasers light propagating underwater don't tend to work very well. Seawater is very absorbing in the yellow orange, red and UV and infrared and even in the blue green window is more absorbing than air. You also have particulates that scatter the light, and any blue or green laser beam would be very visible. Even with sunlight, it gets dark pretty fast underwater, by the time you are about 200 meters underwater almost all the sunlight (even the blue green) is absorbed. The strong absorption means that probably the lasers need to get pretty close to do a lot of damage. Too much power you cold also start heating up the water in the beam and that could cause bubbles or reflections reducing the amount of power that can reach your target. Going from the higher index of refraction water or glass to the air inside the dome you could have total internal reflection. The effect of that is that 100% of the laser beam would reflect away from the dome unless the laser beam within a range of angles called the critical angle. So the laser beam to work the best would need to be perpendicular to the glass surface or at least within the cone defined by the critical angle. [Answer] I'm a +30 yr veteran with lasers. The glass is not the problem... the water is. Ocean water absorbs a lot of light. Laser communications struggles with submarine environments (see: <https://www.sbir.gov/content/unique-high-powered-bluegreen-laser-communication-system-submarines-0> and <https://archive.navalsubleague.org/1988/laser-communications-with-submarines>). Given the exotic wavelengths required to get small signals (laser communications) through ocean water, I would consider it completely impractical to user laser weapons in the ocean. In additional to materials that absorb, there are many particles in sea water that will scatter visible light. I would consider re-writing your story to imply that an undersea dome is well protected from laser / directed energy weapons. [Answer] ## You can't use lasers or guns under water Lasers: Water refracts and absorbed lasers. Every 10m that your laser travels, it will loose 1/2 of its potential energy. So even if your "bottom of the ocean" is somewhere relatively shallow like on a continental shelf at a depth of 100 meters, that means your laser will lose 99.9% of its energy before even making it to the dome. Furthermore, as it heats up the surface water boiling it, the bubbles and steam will cause extra refraction making the water essentially opaque to your laser long before your beam can cause any significant heating to the dome. Bullets: Drag is amplified based on how fast you are going and your proportional size. Because water already has a lot of drag, and bullets do all of their acceleration on the front end, a standard firearm can only pernitrate a few feet of water before coming to a complete stop and just sinking at it's terminal fall velocity which will not be very fast at all. The most specialized underwater bullet in the world, the CAV-X, has an anti-material range of 17m and an absolute maximum range of 60m which still is not enough to reach your city. ## This leaves you with Torpedoes and Depth Charges When going for range under water, big, slow and steady wins the race. A torpedo can go much farther than a bullet using the same amount of energy. Part of this is because drag is exponentially proportional to your speed. While an average bullet travels at over 300mps, an average modern torpedo moves at only 25 mps, using sustained acceleration. This means the an average torpedo has ~150 times less drag for its surface area than your average handgun. Also, keeping the propellant onboard means that the torpedo tends to be much bigger and longer for its proportional effect compared to a bullet. Because the square-cube law applies to resistance, a large object moving though water tends to experience much less resistance compared to its size than a bullet. It's like the difference between a bug being able to stand on water and a human sinking into it. Torpedoes can also use more energy dense fuel sources than bullets, and can take advantage of creating a sustained bubble jacket around them for more thrust and reduced drag. All these advantages add up to ranges that are measured in kilometers, not meters. If you're going for a more low tech weapon, then use depth charges. Powered by gravity, you can simply sink them and have them explode when they hit the dome. ## Why the underwater city did not completely fail from the bombardment In the contest between a large explosive weapon and a glass dome, it sounds safe to say that the explosive will win hands down. That said, when building for large scale habitat for hazardous environments, redundancy is a key safety feature. Many large naval ships and submarines use double and segmented hulls allowing them to take structural damage without losing the whole ship. So, it is safe to say that your under water people building something the size of a city would do the same. The way a [double hulled dome](https://www.setareh.arch.vt.edu/safas/intro_imgs/dome.png) would work is that you have 2 domes, one inside the other. The torpedoes and depth charges could blast holes in the outer dome, but unless two shots hit in the exact same place, the inner dome would be fine. It is also important to make sure the dome is cellular because glass shatters; so, if the outer hull is made up of 1 meter glass hexagons, then when a torpedo hits one, it would limit the damage to a smaller area. Basically, your outer dome would work like the ceramic tiles in often found in [flexible riffle armor](https://www.pewpewtactical.com/wp-content/uploads/2021/05/81.-Body-Armor-Test-Mira-Level-4-Black-Tip-1024x568.jpg) where they are designed to shatter. As for segmenting your city, you are probably picturing a giant dome covering a bunch of terrestrial style buildings. But this is horribly unsafe meaning you are just one mechanical failure away from instant death. Instead each building under the dome could be an individually functional underwater environment. This way, if the dome ever breaches, they can all just retreat indoors while the engineers patch and drain the dome. Or, and ever better approach would be to ditch the giant dome all together and go with many smaller domes connected by airlocks. The best thing about segmentation is that you can plausibly lose specific systems an not others. So, perhaps the city still has power and O2 scrubbers so your heroes don't instantly die, but perhaps the water purification dome and communications systems were destroyed during the bombardment because they were in domes that got hit. [![enter image description here](https://i.stack.imgur.com/ZulPH.png)](https://i.stack.imgur.com/ZulPH.png) [Answer] I had laser eye surgery a long time ago and they have an interesting approach to destroying minute amounts of material behind a lens (aka my eye). They use two half strength beams that when focused independently intersect at the spot (delivering 100% power) where they want to burn away lens material. This was done repeatedly to remove a thin layer over a wider surface area with a high degree of 3 dimensional precision and minimal collateral damage. If you multiplied this several times and had 10 or 100 or more lower strength lasers targeting specific high value targets, each laser would interact minimally with the barrier/glass dome reducing the effects of dirt/defects/heating. If the dome was underwater, sufficient ambient cooling might occur. All you need is multiple attack vectors with direct line of sight to the target (easy when attacking from above in a world with gravity sufficient to hold down water). Another way to look at this is how a natural concave lens works or even a magnifying glass. It bounces/refracts light off a dome shaped surface/lens to focus on one point in the middle. In effect it's an infinite number of "lasers" pointing low power light into one spot of high intensity power. Don't quote me, but I believe this multi laser approach might also be in use for military grade anti missile defense "shields" since it naturally provides layers of redundancy and reduces the risk of friendly fire/innocent casualties. For example slicing the wings off a nearby plane in the line of fire as the laser is tracking the target. Note that in this situation, the laser is aided by the explosive nature of the missile and fragility of precision guidance systems. It's doesn't have to produce devastating destructive power on it's own. Edit: there could be quite a cinematic opportunity here. It would literally be raining down lasers. You'd have people see little red dots appear like rain drops unaware of what's happening. A side on shot would show a "downpour" of red lines, and everything bathed in red. The lines would then swing around searching for a target. Masses of them would swarm on people or anything combustible. Then the explosions would start; barrels, gas mains, aircraft wings in mid flight... panic and people running seeking shelter. Large clouds of smoke and debris would refract the lasers into a blinding lightshow. When the dust clears, slowly the lasers switch off one by one like the lights on a stage. [Answer] Existing answers show that lasers would kind of work. But I don't think they would work all that well. If you went with lasers you should use pulsed lasers, their damage is pretty "mechanical" and instantaneous. The obvious solution here is that laser was used to light up something explosive in the city, next paragraph shows why direct laser damage isn't too good here. 1kJ pulse creates hole in water of about 1 cm in radius. Good enough vs people, but a great many shots would be needed to take down a building. However, damage threshold of glass is a bit of a problem. Add nasty stuff on the dome surface, and you would be very lucky if you get damage threshold at 10J/cm2, but more likely only 1J/cm2. So, your blaster of kJ laser pulses would need a "window" with diameter of say 0.2m... and it is just a person-killing laser that wouldn't do much structural damage. But, there is a better solution. Sound/shock waves. Given water setting sonar and the like are very well developed as should be various explosives. So, how the destruction went? Someone created many shock waves around the dome, propagating towards the dome. These shockwaves interfered constructively in the center, producing huge destruction (direct damage or resonance). The dome probably shook quite a lot too but managed to withstand this - after all, it is supposed to protect you from explosions to some degree, isn't it? How were shockwaves created? Using tons of computer controlled depth charges which produce little explosion making a strong mostly directional shockwave. You can use lasers for that, but ordinary explosive works too. Previously, such charges might have been used for imaging/scanning/... (think spy drone sending pings and listening for echo), and nobody was able to use them offensively in this way before - no good enough timing. Then someone managed to connect millions with computer control and a simulation of propagation, making the big kaboom. A typical dome shape is helpful because stuff you send against the dome and gets reflected is dissipating, while stuff that gets through is converging to the center. This is similar to the laser, though you generally wouldn't imagine to cover the whole dome with lasers. Besides, unique advantage of sound is that even reflections from the ground that reflect from the dome once again converge to the center, amplifying damage. So, you can detonate some charges now, and when the wave reflected from the ground reaches dome, send another shockwave to add to the first one. Then another, and another - essentially pumping energy inside the dome, until everything inside is destroyed. Another nice thing I see is that this approach can use resonance for mostly no damage to anything except the primary target, if its resonance modes are known. [Answer] # The glass forms a thin layer upon being struck by an explosive. The glass dome is self sealing and repairing, and upon being damaged forms a bubble on the inside which tends to deflect explosives and other debris from penetrating. This glass is however quite thin, and a laser weapon close by can blast the city from the outside after a collision. The surface dwellers would drop depth charges, and then have close by submarines rush in while the dome was repairing and blast those inside with laser blasts. It isn't plausible that a dome of glass would be fine if it couldn't self repair, with lasers or other weapons. [Answer] If I wanted to destroy an underwater dome, I'd use a [depth charge](https://en.wikipedia.org/wiki/Depth_charge). It slowly sinks through water (optionally camouflaged, so the underwater guys won't know that it is dangerous), and explodes near the dome, rupturing it. [Answer] # Siege There's no practical way to damage an underwater structure with a laser. There's just too much water and marine life in the way. Especially if it's beneath a glass dome and you don't want to destroy the dome. There are simpler things to do. First off would be to blockade the underwater city. Everyone needs food to survive, is the underwater city totally self reliant? Can it be cut off from its supply chains? Can we hinder food growth within the city - eg deploying plastic balls to cover the ocean over the city and block sun? Simply preventing the city from getting food is simple, cost effective, and safe. This will leave the city in tact but decaying. [Answer] A siege A city enclosed in a glass bubble with few doors is the perfect target for a siege. Rather than bombing the city you might say that is was isolated for some time until most of the inhabitants starved to death. ]
[Question] [ The Emperor (may he live forever) plans to visit the Solar System on a rare royal visit in ten years' time. The Bureau for Interplanetary Tidying have decided that the Asteroid Belt is an eyesore that shouldn't sully the eyes of His Mightiness and needs to be cleaned up. The obvious way to do this is to form them into a single body. Clearly, moving every single asteroid individually would be incredibly energy expensive. Is there a way to start a domino type reaction so that the asteroids assemble themselves over a period of 10 years or so? Here is what I have in mind when I talk about a domino reaction. <https://youtu.be/5JCm5FY-dEY?t=32> [Answer] How difficult would it be? Unfortunately, your timeline is too tight for any of the easy options to work. The mass in the asteroid belt is highly concentrated. Between them, [Ceres](https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)) (~30%), [Vesta](https://en.wikipedia.org/wiki/4_Vesta) (~10%), [Pallas](https://en.wikipedia.org/wiki/2_Pallas) (~8%), and [Hygiea](https://en.wikipedia.org/wiki/10_Hygiea) (~5%) make up about half the mass of the asteroid belt. Combining these into a single body is (relatively) easy, but slow and energy-intensive: unless you're at least a type II civilization on the [Kardashev scale](https://en.wikipedia.org/wiki/Kardashev_scale), you're looking at a timeframe of decades or centuries just to get them into the same place through creative use of solar sails. Simply bringing Vesta adjacent to Ceres in under a decade will take on the order of $10^{28}$ joules (equivalent to diverting the total energy output of the Sun for one minute). Once you've got them together, the only practical way to combine them without scattering debris all over the place is to melt them first. Melting Ceres will require on the order of $2\10^{25}$ joules to heat, and then another $4\10^{24}$ joules for the actual melting. This is on the order of the [total solar heating of the Earth in five years](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#Over_1024_J). The full asteroid belt will take about three times that (a Kardashev type I civilization couldn't quite do it in the allotted decade). Cooling is out of the question: unless you want to risk thermal shock shattering your new dwarf planet back into an asteroid belt, you're looking at cooling times of millenia. A domino effect of starting small and letting things work their way up isn't an option. That already happened, and the result was the asteroid belt as you see it today. The clear areas around the orbits of the planets aren't the result of those planets sweeping up the available mass, but the result of those planets ejecting that mass from the solar system. It also takes far too long: current models indicate that [the clearing process took around a half-billion years](https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System). The asteroid belt exists because Ceres isn't large enough to clear its neighborhood without help. If you had more time to work with, you could attach an outrageously large solar sail to Ceres and fly it around, using its gravity to throw the rest of the asteroids into unstable resonances with Jupiter, leaving it the only body in the asteroid belt, but this is (a) slow and (b) cheating. [Answer] Short answer, no. The asteroid belt is incredibly sparse, where your chance of seeing another asteroid from the surface of one with the naked eye is pretty low. There's no simple way to overcome the momentum of every asteroid. They would all require manual adjustments to their orbits, many of them requiring multiple burns to reposition them and collide them with Ceres (the largest asteroid). [Answer] Probably not all in one go, but along the way why not have some fun, save your job and give the Emperor something to smile about. Say you have a sixteen space tugs to work for you - first thing first, order 12 of them to pop out to the Kuiper belt and drag in a dozen matching 100 Km diameter KBO's (essentially comets), whilst this is happening, get the other 4 to grab Ceres, Vesta, Pallas, and Hygiea from the belt , and in the most efficient way place them equidistant around the inner edge of the belt. Meanwhile the other tugs are draging their loads into equidistant positions between the aforementioned roids. The tugs can then proceed to push all these objects at optimal speed around the belt to gather mass as they go, gradually increasing the diameter of orbit as they clear debris. "But, what if the Emperor comes before the job's finished?" I hear you cry in alarm. Worry not, approaching from the Pole of the solar system (on the Sun's axis of rotation) his magnifience will see: - centre of his view, dark save for the sun shining like the twinkel of humour in his eye, then the inner planets, the sharp inner edge of the belt carved and delineated by the 4 planetisimals and the comets then like a great iris with their tales radiating outward. The wise and benevolent one will recognise (with judicious prompting) the magnificent sight of a likeness of his own eye gazing benignley upon the universe, and revel in his subjects rejoicing and adulation. [Answer] Assumption: There's enough mass in the target asteroid belt to make a planet the desired size. As amazingly powerful as gravity is, it's quite a bit weaker than kinetic energy unless there's a whomping lot of mass nearby. Consider, for example, the impact of a baseball on a bat. Eventually it falls back to Earth — but for a moment, it's free. Now let's go to space where we're trying to bring asteroids together and, especially at the beginning, you don't have enough mass to guarantee that the chunks of asteroid that fly off when two come together return to the central mass. What are your options? You don't have any. This process would be slow. * You can use an net the size of your final planet to sweep around the orbit and collect stuff. The amount of energy needed to do this is so great that it begs the question "why are we doing this, again?" * You can plop thruster packs on asteroids to speed them up a little, thereby causing them to come together (hopefully gently) with the stuff in front of them. Somewhere around a third the way throughA complete guess you could probably dispense with the thruster packs and wait. The final planet would need to swing around the orbit for a very long time (veeeerrrrrryyyyyy looooooonnnngggggg ttiiiiiiimmmmeeeeee) to sweep up the debris. * You can get them moving faster, but this means debris winging off into space. You'll build the basic planet faster, but it'll take longer to sweep up the debris to finish the job (meteors are not your friend, you must clean up). But, even if you did these, how long before you have a planet? Pressure would build, heat would form... eventually you'd get the right kind of core, etc. You'd likely need to drop a bunch of methane/water asteroids on the thing to kickstart an atmosphere.... Conclusion Ten years? The uneducated reader would probably never think twice about it, but it's totally unbelievable. I can't see how you could do it in less than centuries, maybe millennia. You're dealing with so much space, so much mass, so much energy... there's reasons why spacey things happen slowly. When they happen fast, they tend to be catastrophic. Edit: I didn't think to ask Chasly what's to become of this planet(oid)? Derived from our own asteroid belt, it won't be big enough to develop heat or hold an atmosphere and might not be enough mass to stick together as a cohesive ball. In other words, the dirt clods may simply hang together as dirt clods in space until gravitic distortions from the orbits of other planets start spreading them out again. In astronomical lengths of time, they wouldn't stay together very long. [Answer] Nanites Self replicating nanites/robots eat the asteroids and make more nanites/robots. The nanites have their own propulsion system to track and eat other asteroids and so on. See [Replicators](https://en.wikipedia.org/wiki/Replicator_(Stargate)) Unless you have a exponentially growing system system, you will never clear it in time. [Answer] You've specified that you want a pure domino effect rather than a propelled solution for herding / collecting each asteroid, but this isn't possible without flinging the new planetoid cluster(s) into a new orbit and making an even bigger mess long term. If you just need to sweep some debris under the rug for the duration of the royal visit, this may not be a problem. ### Why dominoes won't work As already mentioned, the deadline for the ~~King of the Cosmos~~ Emporer's visit is only 2\* orbits around the sun for a given asteroid. Say you stick a giant butterfly net force field on a medium asteroid so it can gently scoop up all the other asteroids [Katamari style](https://youtu.be/jQrSUKEzd28?t=21) and eventually stick to Ceres\\, and have a giant space tugboat give it a starting push to a new speed. \* 2-ish, but let's stick with simple math to illustrate the point. \\ Saving the biggest for last saves time and energy. Your ~~snow-~~ asteroid-ball either has to move much faster, completing 3 laps instead of 2 just in time to catch the asteroids originally just behind it. Ignoring acceleration times altogether, you have a 50% increase in orbital velocity, and the orbital radius will therefore increase considerably and start interacting more with Jupiter's gravity. Or you could slow down and complete only 1 orbit (50% drop in speed) and give Mars a new moon (or completely re-texture it\). Except that long before you finished either cycle, the initial snowball mass will have already have moved to its new orbit and be far away from the remaining asteroids at the end of the original orbit. \ Not necessarily bad - another user already mentioned terraforming. Instant habitable planet, just add water and allow to cool 10,000 years. If you are just worried about tidiness and not creating a single mass, you could possibly pull off domino stacking by instead collecting 8 planetoids (or 6 or 12 or His Majesty's favorite number) of equal size and spacing. ### Thinking with Portals! However, you haven't specified your civilization's exact level of technology beyond some very basic clues - obviously they have space flight and, and enough power to get ships around interstellar distances, but probably not FTL or unlimited energy and fabrication time. The minimum power required for any giant problem is [a 9V battery and an SEP field](https://hitchhikers.fandom.com/wiki/Somebody_Else%27s_Problem_field), but I'm assuming that's not an option either. Therefore, I propose a middle ground solution (which may or may not fit your particular universe) involving a probably reasonable amount of power, and a fairly large ~~orange and blue portal gun~~ pair of wormgates. A single ship travels to Ceres and leaves one of the gates floating nearby, then slows down a bit with the other one and take the full 10 years zig-zagging backwards around the belt. Each time you reach an approaching asteroid, power up both gates for a few seconds/minutes and lasso it, leaving it parked in formation right next to Ceres\\\. Power back down, shift the receiver slightly, and move to the next one while the gates recharge. If you need to move faster than 1 crew can handle, send a handful of collector ships with their own gates (either a separate pair or all tuned to the same destination). \\\ Crashing everything together would make a debris field that was unsafe to operate your gate in, if not sending pieces back into separate orbits. [Answer] With sufficient effort, this could be done. It would require the manual alteration of the orbit of each asteroid. Bear in mind that the total mass of the asteroid belt is around 4% that of the moon, and that around half of that mass is already contributed by only 4 asteroids. The remainder are tiny and barely significant. It would be an awful lot of work for basically no gain. [Answer] Other posters have focused on two large asteroid belt clearing problems: excessive time and excessive energy are needed to suspend disbelief for the genre of hard science fiction. Excessive need for space or time seems the lesser issue in a Einsteinian universe. To suspend excessive space-time, I agree with brichins' idea of using wormgates, a SF technology that harnesses macro wormholes (as opposed to quantum wormholes that seem closer to present physics theory). I agree, in validly suspended SF, that each end of a sizable wormhole can be placed where needed to move even large planetoids like Ceres. I think all asteroids could be teleported adjacent to each other, with matching momentum for bolting (stone) and welding (iron) into something(s). Something(s) 4% the size of the moon per Arkenstein XII. I see no obvious SF reason why wormgates can't teleport other wormgates in a preprogramed pattern around the asteroid belt. What I might call leveraged teleporting, starting with a fleet of cargo starcraft powered by (consensus SF) hyper/warp drive. Teleport clearing the whole asteroid belt certainly wouldn't be instant, and could take years, because electrons and photons - even in the peripherals of quantum computer circuits needed to solve such an enormous set of calculations - travel at about 95% of light speed (in copper). One will need a great many individual computers/processors/hardware, and quite at lot of (consensus SF) subspace signaling to project managers in, say, a triangle of bases orbiting the solar system. Debugging committees, even with the help of AI, will have to solve many initial project design issues. That's not going to change in the future. Mark's delightful analysis of the excessive energetics seems more troublesome. Einstein seems to allow the cheating of our ordinary calculations of space and time, but not the cheating of mass-energy conservation. Mark probably can calculate how much energy it takes to move objects into higher orbit, if it's 4% of the moon mass, raised from the asteroid belt, to spiral orbits into Jupiter for slow disposal. Jupiter disposal has its own set of problems, but I've read that Jupiter is too small to be set on fusion fire. I don't know how much recoverable, reusable energy, and lost, heat-dissipated energy it takes to operate a wormgate. Even if you recover most of the reusable energy after the worm field collapses, to inflate the field, one still has to store a great deal of energy joules in pre-charged capacitors (sized 10^xx farads?). For story purposes, I think the average reader better comprehends kilowatt-hours (at 20c each) to the equivalent physics joules. Will the Emperor pay for the heat-dissipated energy? The good news is that your story is premised as tongue-in-cheek SF like Hitchhiker's Guide to the Galaxy. That genre depends more on clever writing than a serious SF suspension. You've mentioned a bureaucracy, so your story could be one of massively bungling the project, yet in Homer Simpson fashion, all the bungling cancels itself out to result in an unexpectedly successful conclusion. One way to compress 10 years into a short story is to tell it as a series of dated historic documents, like royal proclamations, emails, radiophone transcripts, corporate invoices, lawsuits, arrest warrants, and news accounts. You could cover over story holes with puzzled notes from a future historian, writing that he can't find documents to explain how event X occurred improbably - which works with tongue-in-cheek SF. [Answer] Impossible Since the astreroid belt is exactly that due to the gravity of several planets making sure that any "body" would be pulled apart as it forms, or after it is formed. The whole asteroid "belt" is proof of this effect. So it is impossible without changing the whole solar system this is in. At which point you can no longer speak of an asteroid belt anyways. ]
[Question] [ Vocalization has a number of features that make it a very robust natural form of communication: * Variable volume from whisper to shout, roughly scaling from direct to omnidirectional; * Equally effective in daylight and total darkness, doesn't require visual contact; * Precision of hundreds of distinct phonemic combinations; * Works over significant distance, even through/around some barriers. Considering the possibilities of alien physiology and environments, is this as good as it gets or are there other methods as (or more) robust? --- # Expanded The bounty expires tonight so I'm going to go through some of the suggested answers below to illustrate how they fall short of vocal communication, in the hopes it will inspire more answers. Remember: I'm not saying it's impossible for these forms to evolve, I'm saying they are fundamentally more restrictive than vocalization. Smell * Prevailing wind conditions limits the direction of communication. "Speaking" to someone upwind of you could be impossible, even over a short distance in a light breeze. Touch/tactile * Speaking to someone out of arm's length would be impossible, and the ability to speak to multiple people is limited to the number of appendages you have. Bioluminescence/infrared/skin pattern * Requires visual contact by the recipient and a narrower range of ambient lighting conditions, and may be impossible during the brightest part of the day or at night/in darkness. Writing * This also requires visual contact, but even more restrictive is the necessity of writing media and tools. It's also arguable that any form of natural communication can develop written/recorded forms, so a writing-only language would be inferior to all others. ## Potential There are a few references to electromagnetic communication (such as, but not just, radio) I think are begging to be explored more. Such a mode of communication could penetrate barriers and distances that stop vocalization and conceivably allow greater directionality (e.g. the ability to "whisper" to someone in another room, to speak to someone at the bottom of a pool, etc). But can a case be made for it evolving in nature? [Answer] Effective communication really depends on what your creature abilities are and the constraining environment, as you have said. Vocalization seems to be the most robust because we use it daily to overcome the need of visual contact. Have you considered sign language, or gestures as communication method? It works through noisy situation. So, rather than sound is better than gesture, both are complementing each other. When the sound communication is limited, you can use visual communication, and vice versa. You can also try to devise [smell language](https://worldbuilding.stackexchange.com/questions/65210/how-could-scents-develop-into-a-full-language) or taste language. Animals have already used smell of pheromones to mark territory, so it's a more efficient form of communication in term of asynchronous communication, similar to leaving an email for your friend to read later. As for taste language, well, just imagining it would be weird. Try imagine two aliens French kissing each other, while their saliva tells their partner what they are feeling right now. This saliva might contains hormones that tell the partner their emotion state (happy, sad, or angry - well, it's difficult to imagine someone's angry and kissing each other) Or you might want to try tactile signing as tactile language (weird, yeah). Deafblind people use that to communicate. I feel very weird when I see it at first. Here is a video of tactile signing: [Tactile signing for deafblind](https://www.facebook.com/ColinAllen.WFD.President/videos/908291479259928/) and [Soccer tactile signing](https://www.facebook.com/inthenow/videos/904745326342504/) --- tl;dr Is there anything more robust or not, it depends on the environmental barrier and the senses your alien. You can try to combine languages from the five senses, or even create a sixth sense. Note that telepathy is basically cheating in my opinion, because it allows you to communicate over distance disregarding environmental barrier (visual or auditorial). But that just depends on how you define the telepathy. [Answer] The visual signaling of cephalopods has promise, signaling through pattern and color change in the skin. Their only limit is their poor color vision, which you could change. Bioluminescent animals could communicate in the dark. Distance is even better than sound since they are limited by line of sight only. They can even hold two conversations at the same time. Look a this picture with one pattern being shown to a female and another being shown to a rival male. Sight does get drowned out so many many conversation can be happening at the same time. [![male and female cephalopods (and an arrow indicating a second male to the right), where the male has two distinct patterns - one in the direction of the female, the other in the direction of the rival male](https://i.stack.imgur.com/xGNwk.jpg)](https://i.stack.imgur.com/xGNwk.jpg) Source: <https://www.wired.com/2017/02/squid-communicate-secret-skin-powered-alphabet/> [Answer] You can try Wi-fi. Or more generally, radio wave. You just need a natural antenna. After some research, I found nothing similar on Earth (sorry !). But in alien settings, you can make your specific radio wave organs (an emitter and a receptor). It wouldn't be this incredible when you think of the feats of engineering life is capable of on our own planet. Think of bat's echolocation or electric eels' capacities. Some fish can generate electromagnetic fields, too. Animals can already adopt a lot of physic phenomena to suit their needs. The pros of this (compared to voice, for example), are multiple. A very long range can be attained depending on the frequency and the power used. The data transmitted could also be very rich and I think the main limitation is the brain capacity of your alien, for interpreting and composing these signals. Almost every properties of those signals are adaptable in a worldbuilding case: range, bandwidth, power. This could be quasi-telepathy or just a 30 meters limited communication. [Answer] Are there any natural forms of communication as robust as speech/vocalization? [![genesis in Hebrew](https://i.stack.imgur.com/7Lblt.gif)](https://i.stack.imgur.com/7Lblt.gif) Speech / vocalizations are good. But writing is better. Writing has permanence, which is not true for any sounds or gestures produced by a creature. You cannot read in the dark, but you can wait for it to get light. You can refer to a written communication again and again. You can add to it. You can translate it. Maybe I cannot speak to you at the time, but I can pass you a note. You can read it, fold it up, and read it again later. You can leave written words for others to read and consider, exactly as I am doing now. Writing is an immense achievement. Does it count as a natural form of communication? Right now I am typing on some tech miracle, but I can write you a note on a rock with my finger as a pencil and mud as ink. That seems pretty natural to me. [Answer] There are some environments where speech communication does not work: 1. Vacuum: Speech needs a transport medium like air or water. In the absence of a transport medium, speech communication cannot be used. 2. Noise: In a very noisy environment (think of permanent thunderstorms or permanent earthquakes) the cost of producing a loud and clear sound signal may become too high to be effective 3. Presence of enemies/predators: The sound signal is "for everyone", it is not possible to bundle it in a laser-like beam to a target recipient. Having said this: As life on Earth clearly shows, sound signals are the means of communication of choice for many lifeforms. Other kinds of signals (Bee's dances, chemical markers (ants), optical signals) play only a minor role in communication, but they aren't completely ruled out. No life form we are aware of uses radio waves for communication naturally, this tells us something. Maybe radio waves will be used by life forms that can go out in the vacuum. [Answer] Speech is sound waves transmitted by air for which humans have evolved a receiving and interpreting system so they can use it for communication. Technically, any length and type of wave that can carry the signal, be transmitted and received within the environment and translated with precision could replace it. Imagine the same principle but with light instead of sound, or X-rays. Aliens could communicate with very complex QR codes for example, even moving ones. I think it only depends on the environment you want to create what kind of communication would have evolved. [Answer] On a physics point of view, you could consider the four [fundamental interactions](https://en.wikipedia.org/wiki/Fundamental_interaction) of the standard model: * Strong (bonding quarks together) * Electromagnetic (light, sound) * Weak (interaction with neutrinos) * Gravitation (interaction of planets) I suppose physically sending a written message or using the transfer of matter can count as using matter cohesion, so strong interaction. Electromagnetic is what is used in our world for non-written or numeric communication, through light and sound signals. Detecting weakly interacting messages needs big amounts of mass and is a very noisy process (for instance building [neutrino detectors](https://en.wikipedia.org/wiki/Neutrino_detector) with huge pools of water). Producing gravitational waves involves catastrophic events, such as destroying stars, and are also [not easy to detect](https://en.wikipedia.org/wiki/Gravitational-wave_observatory). Because these signals can travel for years in the universe while barely interacting, on gigantic time and space scales they could be efficient to communicate. On our scale, choosing electromagnetic signals is definitely a sound choice. [Answer] Even humans have other ways of communicating, but we are not rationally aware of them. [Human non verbal interaction](http://www.independent.co.uk/life-style/health-and-families/features/the-face-of-fertility-why-do-men-find-women-who-are-near-ovulation-more-attractive-10359906.html) As such, some aliens could have very developed pheromone glands and could control their release. So you could get to use it as a language. Electromagnetic could also work, if the alien would have a specialized organ to perceive such changes. [Answer] If you proposed an alternate communication it would have to be able to communicate danger warning to start with as this is widespread among animal groups of many types. I assume we are talking about a cooperative "people" with social organization. Vocalization transmits feeling and fears and joys, excitement, child care, bonding, all that. Language was just an outgrowth of that when someone was grunting enthusiastically and another said, "What is it this time?". Yep, that was the first sentence in human history. Would/could written language come about without first being spoken? Music, song and dance are also supposed to be quite fundamental to our social origins and shared experience. Are these folks of yours deaf? I accidentally spent a lot of time with Mayans in their tiny village. Not much talking ever went on (though I hear they do more of it now with tourists about). But they lived very simply and in small groups. Diet and activities were the same from day to day and could be shown, and thereby taught, through demonstration. I also lived with Navajo and Filipino families that used borrowed words for anything complex or technological (down to the level of "furniture" or "dishwasher"). So my two points are that emotional communication is difficult without sound and technology is limited without conversation. [Answer] Infrared Communication: Perhaps your aliens have the ability to see infrared, and control the temperature within parts of their bodies. Consider then, how cool it would be if they communicated by changing the "heat pattern" within their bodies to communicate their thoughts and feelings with one another. Maybe even, they could alter the temperature of the air around them to get the attention of one another when they aren't actively "looking" at each other. A blast of hot or cool air means "HEY PAY ATTENTION!!" This would fit the conditions of: 1. Being able to scale (they could run hotter or cooler). 2. Being effective in night or day (you can see through an infrared lens in night or day scenarios) 3. Having a variety of precise and distinct characteristics within their "language" (variances in heat patterns) 4. Working over significant distances (you can see heat traces through infrared from far away and through some barriers) Vibrations Through Touch: If you want to discuss a form of communication that might be similar to speech/vocalization, but slightly more alien, one method could be "hearing" through a sense of touch. Someone can feel you blow air on them from a distance, and you can theoretically alter the scale of air you release as well as the pattern. I understand that this is almost exactly how hearing works (pushing molecules through the air in different frequencies and patterns so that our ear drums vibrate and communicate the meaning to our brains), but it seems more alien when you consider "hearing" through the sensation of touch on your skin. ]
[Question] [ I'm creating a story set on a near-future Earth in which undersea colonization is fairly widespread. I want large (think undersea equivalent of a battleship) and, especially, expensive submarines to experience extreme military advantages over larger numbers of smaller, cheaper subs. Ideas I've considered: * Advanced armor * Widespread use of EMPs and signal jamming Would either of these help to explain such a military condition? What other technological conditions might? [Answer] Sadly bigger won't mean better. Bigger subs will be less maneuverable than smaller subs and thus prone to flanking and hit & run tactics (see [pirates](http://www.cindyvallar.com/tactics.html)). An additional advantage of many small subs over one big subs is that a single big sub is easier to hit. A group of subs can split, scatter and reform easily and thus fare much better in a fight. So why would we still favour bigger subs? Smaller subs will have to fill way more specialized roles. They cannot carry lots of fuel, armor and armaments. Bigger subs can be much more complex and versatile, though the disadvantages mentioned still hold. If we pull the bigger subs back from the frontlines we can get some better result. In modern naval warfare aircraft-carriers play an important role as the backbone/center of a strikeforce. They carry ammunitions, fuel and other things while also providing a base for refueling and parking smaller limited strike-craft. So we can make the big subs into sub-carriers that each support 2-3 groups1 of smaller hunter subs. The big carriers can be heavily armored as we don't care much about weight - after all, we want them to sink! Thanks to the [square/cube law](http://tvtropes.org/pmwiki/pmwiki.php/Main/SquareCubeLaw) we have more material available for armoring the big sub than if we were armoring the same volume of smaller subs. When attacking they would likely send out two of their three groups, keeping at least one group back for defense purposes. If you are fine with having them fill in more stationary roles you could easily scatter minefields around their position, perfectly safe for friendly subs but deadly for any attackers. What if I want them to be even bigger? Additional size demands purpose. If you can find reasons why they need to grow bigger, then go for it. Just remember, additional size requires additional resource in form of materials to build it and technicians to maintain it - any unused spaces still have a cost attached to them! One possibility is to make the surface world inhospitable due to whatever you choose. Force people to go underwater. As the military needs lots of support personnel, they will take on civilians and sections of the bigger subs will turn from living quarters into little villages. In time those subs will grow with e.g. additional influx of refugees. Little city districts will form in the inner sections of the subs, surrounded by factories and machinery which is in turn surrounded by the military forces it is built to support. --- 1Well, as many as you want to be fair. The only limiting factor is the size of the sub and the kind of docking facilities you wish to implement. [Answer] Hmmm.... As you increase the size, volume goes up faster than surface area; a 1 unit cube has a volume of 1 and a surface area of 6, a 2 unit cube has a volume of 8 and a surface area of 24, a 3 unit cube has a volume of 27 and a surface area of 54, and so on. That means that if you want really thick, heavy armor, you can make it a lot thicker on a big sub than on a smaller one before it starts causing bouyancy problems. So that's one possibility. Alternatively, you could look at the underwater equivalent of aircraft carriers. Maybe have more effective attack subs (very fast super-cavitating ones, maybe?) that are a lot more combat effective than normal subs, but have limited endurance (like fighter planes) and need the equivalent of a carrier to supply them and for the crew to live in. (I'm assuming that only having to pack enough life support/fuel/supplies into your fighters to keep them going for several hours to a few days should let you make something more effective than something that needs all the support and fuel for several weeks or months...) Or some critical piece of equipment (highly effective weapon, defense, or whatever) that is sufficiently large that it needs a big hull to fit it in. [Answer] Bigger submarines are for longer missions. Submarines are thought for stealth, big and stealth do not go well together. The only sensible reason to make bigger ones is to stuff into them more weaponry and recycling equipment to allow remaining deep and quiet through the rough moments and strike back with enough power. In general nuclear submarines (nuclear in both power and weapons) are much bigger than "conventional" ones. You need much more space to hold the nuclear reactor and you need to transport a sizable amount of ICBMs. To that You need to add space for "enhanced" technical staff. Again: in submarines big is for longer time underwater. [Answer] Active sonar may make it easier to find a larger sub (absent shielding), but underwater, most subs are going to be using passive sonar (listening for sounds) You could go with the "Red October" solution, stolen from the Tom Clancey novel. Namely, a more silent propulsion drive requires substaintially more area. Red October used some fancy new system, but, in general, bigger propellers are quieter. Acoustical shielding may be thick, and in general expensive. That would let you benefit from the square-cube law. Other systems, e.g. nuclear reactors, may also get more silent as they scale up. That can certainly be posited in a reasonable way. [Answer] A size comparison might come in handy for starters. Firstly, the world's biggest submarines. Source: [The world's biggest submarines.](http://www.naval-technology.com/features/feature-the-worlds-biggest-submarines/) > > Typhoon Class, Russia > > > The Typhoon, with a submerged displacement of more than 48,000t, is > the world's biggest submarine class. It is a nuclear-powered submarine > equipped with ballistic missiles. Dmitry Donskoy, the first of the six > submarines in the class, was commissioned in 1981 and is still in > active service with the Russian Navy. > > > Typhoon Class submarines have a length of 175m, beam of 23m and draught of 12m. > > > Borei Class, Russia > > > The Borei Class, which has a submerged displacement of 24,000t, ranks > as the world's second biggest submarine. It is a nuclear-powered > missile carrying submarine serving the strategic naval forces of > Russia. > > > Borei Class measures 170m long, has a beam of 13.5m and draught of > 10m. > > > Ohio Class, US > > > The Ohio Class submarine is the third biggest in the world. The US > Navy operates 18 Ohio class nuclear-powered submarines, which are the > biggest submarines ever built for the US. Each sub has a submerged > displacement of 18,750t. > > > Each Ohio Class submarine has 170m length, 13m beam and 10.8m draught. > > > Secondly, the size of battleships. This is an example of a modern battleship. The dimensions for an Iowa-class battleship are: -- > > Type: Battleship Displacement: > > > > ``` > 45,000 long tons (46,000 t) (Standard) > 52,000 long tons (53,000 t) (mean war service) > 57,000 long tons (58,000 t) (pre 1980s full load) > 58,000 long tons (59,000 t) (post 1980s full load) > > ``` > > Length: > > > > ``` > 861.25 ft (262.51 m) pp > 887 ft (270 m) oa > > ``` > > Beam: 108.2 ft (33.0 m) Draft: 36 ft (11 m) maximum > > > Essentially a battleship-sized naval submarine would have, roughly, double the length of the current biggest submarines. two hundred and seventy metres versus one hundred and seventy-five. This suggests that scaling up submarines to battleship may not be implausible. One consideration is that in a world where undersea colonization is a feature. Submarine freighters and tankers might also exist. While it does make sense that smaller, faster submarines would be better placed to defend and protect such civilian submarines. It's not infeasible that battleship-sized submarines could be employed to take on a similar role to that of battleships. Namely, as a major support unit for a submarine battle group. [Answer] Large submarines in general are more difficult to hide, are difficult to manoeuvre and will have difficulty operating in littoral regions. The only real reason that you might want to have a much larger submarine is to have a long endurance platform which can use much more of the ocean to hide in. This means combining two separate and not entirely ompatible goals. You want a large submarine which can hold stores and supplies for long endurance cruises (or large numbers of weapons, essentially an arsenal submarine). OTOH, in order to truly effectively use the ocean to hide, your submarine should be capable of diving much deeper than conventional submarines, so the crush depth might be well past 500m. A sub which can dive to 1000m can effectively sit on the bottom of much of the continental shelves and be relatively safe from detection hiding in the "clutter" of the ocean's bottom, or alternatively hide under multiple layers of salinity and temperature, making detection much more difficult (dipping sonars to breach the thermoclines would now need to be suspended at least 1000m down to attempt to find the submarine, and it could be at almost any depth between the surface and its crush depth..... A large submarine which is spherical in shape, rather than the conventional "cigar" shape will be able to fulfill many of the desired parameters. A sphere has maximum volume to minimum surface area, is immensely strong and the spherical shape is probably good for ensuring active sonar does not get any clear return (outside of coating the hull with metamaterials to refract active sonar around the hull). A large sphere isn't going to be as fast as a more conventional hydrodynamic hull shape, but this is one of the trade offs that will need to be calculated. As an aside, the USN and the Indian Navy now have boats the size of conventional attack subs which have much of the firepower of larger and more expensive "boomers" (Virginia class and Arrant class respectively), demonstrating that bigger isn't always better. [![enter image description here](https://i.stack.imgur.com/p0Em8.jpg)](https://i.stack.imgur.com/p0Em8.jpg) USS Virginia [![enter image description here](https://i.stack.imgur.com/tGBU6.jpg)](https://i.stack.imgur.com/tGBU6.jpg) Arihant [Answer] As a different option, what about ultra-long-haul submarines? Nuclear submarines' propulsion is effectively unlimited (at least within the lifetime of the submarine), but they are limited by their ship's stores. So if you had several decks devoted to hydro/aquaponics to supplement what could be harvested from the ocean, you could have a submarine that could potentially operate for years without a resupply, and on which the operators could continue to eat healthy meals. This would, by necessity, need a lot more space, and would be more like a roving habitat than a battleship. [Answer] Depth could be a reason, think of a tin can submerged to a mile deep versus the same tin can made from fifty foot thick titanium alloy, the first would implode whereas the latter may have enough strength to deal with the pressure. Thats the most plausible solution I could think of to explain why one submarine was larger than another. This could be tied into the need to submerge to lower depths than smaller enemy submarines. Other reasons could include: * A larger population size * Evolution of predators requiring counter evolution (which as we know, in humans, tends to translate to more advanced and/or lethal technology) * Storage of resources, which also ties into larger population size * Whales develop a second stomach for the digestion of submarines, ties back to the predator scenario * Invention of fusion technology allowing submarines to be fueled by stars, requiring larger subs * Use of nuclear offensive requiring thicker hulls to sustain greater levels of radiation * Acidic seawater due to pollution and requiring more heavily armoured subs with much better water filtration systems * Fatter population because they aren't getting enough exercise at the bottom of the sea * Requirement of solar farms to sustain a population that has never seen sunlight above the waves Theres a thousand and one different ways you could go with this honestly! [Answer] Changes to underlying technologies would naturally lead to larger submarines. Specifically available hull materials and reactor and ballistic missile technology would have the largest impact. ## Hull Materials Availability of cheap supplies of titanium and familiarity with alloying and working with the materials could allow much larger submarines to be built. In cold war history, the Soviets produced several submarine classes with titanium hulls due to the greater supply of titanium in their territories. This includes the [Typhoon Class](https://en.wikipedia.org/wiki/Typhoon-class_submarine) the largest class of submarines build to date (it had a pool inside it!). ## Reactor and Missile Tech If miniaturization of submarine nuclear reactors encountered difficulties or alternate technologies evolved which needed very large amounts of power, then a larger less efficient nuclear power plant would require a larger submarine superstructure to support it. Similarly if ballistic missile tech was less advanced, or other conditions existed (less advanced larger atomic bombs), which required larger missiles then the submarine would again need to be bigger to allow the same military functionality. [Answer] If under-sea colonies are common, then the purpose of at least certain types of submarines could correspond more to their above-water counterparts (for example, cruise liners for underground colonies for non-military applications). For military (and even standard business) applications, think "troop transports" or "cargo ships." Just look up pictures of current cargo planes or oil tankers - they're enormous. Presumably, you'd still need those things underwater, which would require large submarines to accomplish. (Current submarines aren't even remotely suitable for that kind of a purpose). The underwater equivalents of trucks and trains would be nice to have, too. In fact, I seriously doubt that you could sustain any kind of a large underwater colony for any length of time without some economical way of moving large amounts of goods and people at once. A few other things that could cause that: * Colonization of deeper parts of the ocean. * Slightly larger planet leading to more gravity, which necessitates thicker submarine "skins" to cope with the extra weight For "standard" fighting-type applications, though, you'd probably want to stick with smaller, lighter submarines. (Think about how comical it would be to try to have a dogfight with 747s - unless you want comical. If you want to include some humor, you could actually have someone try something like that and have it flat-out not work). A better application fighting-wise would be if submarines were mostly just attacking large ships. [Answer] If global warming melted all the icecaps (Water world) such that there's no longer much livable land, Kevin Costner might prefer to live in a giant city under the sea. Such a city would have the advantage of not having to withstand the elements of the open air. However, changes in the underwater environment would require that it move from place to place, from time to time (e.g. foraging/farming/mining grounds, seasonal areas of cold/warm water, enemy incursions to their area). Now that they're on the move, albeit a very slow move, they ought to be able to defend themselves, particularly against other city-sub-states that are also out to find good places to mine/farm/do the "Under the sea" song. Soon it'll be a red ocean, where gigantic submarines containing thousands of people each are battling it out with "Under the sea" in the background. The horrors of war. [Answer] ## First, can you make super-sized subs? Your giant submarine will require larger engines, more materials, and a bigger crew. Can your fictional world supply all that? Can it accept the loss of maneuverability that comes from a larger vessel? The risks of detection that increase as your vessel's surface area increases? The higher fuel and supply costs? ## Some reasons to go up in size 1. Dive depth. It might be that a larger sub can be built to dive deeper by having a stronger structure and a thicker / tougher hull. 2. naval supremacy. Present day warfare favors air supremacy over naval. The focus is on drones, bombers, and other aerial attack vehicles. Battleships are obsolete. So your world needs a reason for naval forces to rise back to the forefront of military technology (and spending), and for that focus to be on subs, not other surface ship types. 3. Surface conditions. If the surface is no longer safe, then subs become more useful. 1. Biological. If a plague (man-made or natural, zombie or mundane) breaks out, then a sealed vessel below the surface might be safer. 2. Global warming. If the surface is too hot, or subject to too many hurricanes or other violent storms, then subs become safer. 4. Surface threats. If your world's technology has advanced to the point where surface vessels have extremely low odds of survival, then subs become stronger alternatives. Think of the German U-boats and how devastating they were early on during WW2. Now ramp that up. Or an alien invasion that uses a sustained meteor shower to bomb surface targets. Or... You get the idea. If all your ships must be subs, then your subs might need to be big enough for roles now carried out by other vehicles (troop transport, supply runs, etc.) 5. Energy surplus. Maybe cold fusion becomes a reality. Or some other exotic power source. But your big sub can now have all the power it needs, so why not go big? [Answer] On the physics: If you take a sub, scale all its dimensions up in the same way, the resulting bigger sub won't be able to dive as deep as the original one. That is because you are decreasing the radius of the hull as you are increasing its size, and it is the curvature of the hull that allows it to withstand the water pressure. Obviously, you can still increase the size of a sub by simply joining several subs together. Likely, those bound-together pressure cylinders will be enclosed within a thin, non-pressure withstanding hull for hydro-dynamic reasons. Each pressure cylinder, however, will have a rather small diameter, to allow for large diving depths. --- How to explain gigantic subs: Well, you obviously need a reason for large subs. As a matter of fact, subs are relatively poor at actually controlling an area (or water volume). To do this, it might be necessary to use a large fleet of small subs. However, small subs cannot use nuclear reactors, as those have a certain minimal size. So, the small sub fleet would have to do with battery power. But how can you reload your batteries when you are on the other side of the planet, and want to avoid surfacing for whatever reasons? Enter the big sub carrying sub! It would work a bit like aircraft carries today: You have one really big vessel, which contains at least a dozen small vessels, which are the big vessel's eyes and arms. These small vessels patrol the area that is to be controlled, and they strike against any enemy they find within their action radius. Once their batteries are down, they return to their carrier for a battery charge, remunitioning, and some fresh supplies. The carrier sub itself would be huge by todays standards. It would likely contain several powerful nuclear reactors, large ammunition storage areas, and have several places for the small subs to dock. The parts that need to be at atmospheric pressure would all be contained within a number of long cylinders, each no more than five meters in diameter for structural efficiency. This pack-of-thin-cylinders design would go quite well with its purpose of being a carrier of many small subs, I think. The big sub itself would not have much defensive capabilities itself, relying on its fleet of small subs to defend it, just like aircraft carriers rely on their air force to defend them. The big carrier sub might contain a few big offensive missile type weapons, though; weapons larger than the small subs can carry. Such a carrier sub would really be able to control a certain volume of the sea, which is hard to do with the modern subs which are mostly built for offensive strikes on the surface. The modern subs are built that way, because we humans are most interested in controlling the earths surface, for obvious reasons. A civilization that mostly lives underwater would have much different priorities: They would desire to control either water volume, or areas on the bottom of the oceans, so I think, big carrier subs would suit them well. [Answer] A major breakthrough has been made in [stealth technology](https://en.wikipedia.org/wiki/Stealth_technology). The new technology makes a submarine totally invisible to even the most advanced sonars/radars/cameras/etc. Problem: This technology requires a yehudicollider, which is a very large machine that can't be miniaturized. [Answer] Well, some simple answers could be that the pilot race is bigger - perhaps there's a need for more people on board, not just to pilot it, but maybe even to live and work on if it's needed. Or, perhaps, the sea is bigger and the vessels need bigger bulk out of the materials they're made out of in order to survive the sea conditions? I'm not very experienced with undersea stuff, so these are pretty pedestrian ideas from me I'm afraid. Additional considerations... perhaps each ship shape works like a 'key' and they need to be a certain size to get back into the port area or stations? Like, the door wouldn't open for them if they were too little or too big, and maybe these 'shells' are adjustable for certain configurations. Or, of course, maybe there's just a need for bigger and bulkier ships in general - maybe as intimidation against natural beasts/predators/foes? [Answer] ## Drones & Missles / Troopship / Supply & Repair Think of the ocean as deep space. A larger ship has many advantages. A large, deep diving vessel that could launch massive numbers of underwater drones, conventional missiles, nuclear missiles and stay out of the way by going very deep would be very useful - especially if it could raise from a deep trench, launch massive drones and missiles and then disappear again. Additionally, a variant ship could launch amphibious landing craft from deep in the ocean and disappear - providing a profound element of surprise (troops coming out of the ocean) - especially when backed by the battleship variant. Another variant would also be large mobile Supply & Repair ship that stays underwater and provides assistance to the fleet (c.f. [https://en.wikipedia.org/wiki/USNS\_Lewis\_B.Puller(T-ESB-3)](https://en.wikipedia.org/wiki/USNS_Lewis_B._Puller_(T-ESB-3))) These capital ships would then form the backbone of an underwater fleet that takes advantage of being hard to detect, hard to track and hard to destroy. [Answer] There is one reason which may actually become an actuality fairly soon. By covering the surface of a submarine with 'pixels' of materials that facilitate detection of neutrinos (eg: conversions to muon, Cherenkov radiation...) it will be possible to identify the direction of neutrino travel by analyzing the entry and exit spots. This will allow communication with nuclear submarines from base stations without the need for 'dead man's handle' radio signals, or low-bit-rate extremely low frequency radio (radio does not penetrate salt water well). These submarines will have the advantage of advanced command and control. Another advantage is that other nuclear submarines emit neutrinos from the fission reactors, which is unstoppable, and detection will make them visible. Use your fave search engine to find the above is under active research. <https://arxiv.org/abs/0909.4554> <https://arxiv.org/pdf/0909.4554.pdf> <https://tech.slashdot.org/story/15/10/13/1727231/antineutrino-detection-is-about-to-change-the-game-in-nuclear-verification> By the way, China will be deploying ultra large neutrino detectors in the near future. [Answer] Bigger torpedoes have a longer range (possibly even over-the-horizon), and bigger submarines can carry these bigger torpedoes. Bigger submarines carry more torpedoes (real-life WW2 submarines carried only 6 to 24 torpedos). Bigger submarines might also carry aircraft; or carry whatever the underwater equivalent of aircraft might be (e.g. fast drones); or carry inter-continental or surface-to-orbit missiles. Bigger (hypothetical) submarines might also carry its own defenses ... not armour but for example deployable mines, so that it can lay a mine field (and/or sonar listening devices) around itself ... so that it's a mobile fortress. Or, miles of some kind of net. [Answer] More/bigger weapons Battleships were created because they could carry bigger cannons. So maybe bigger submarines could launch bigger torpedos that have better chance to deal enough damage to score a kill. Or bigger size allows for better engine/more fuel meaning faster speed and longer range. Death Star from Star Wars movies was so gigantic because it's main task was to house a huge special weapon with enough firepower to destroy planets. Modern big submarines are mostly that way because they are meant to carry and launch intercontinental ballistic missiles. So maybe there are some special weapons that simply wouldn't fit on smaller subs. During age of sail bigger ships meant more firepower because they could carry more cannons. So bigger submarine could have more torpedo launchers leading to being able to strike more hits on enemy or being able to target more enemies same time. Maybe there are some anti-torpedo devices capable of destroying/jamming launched torpedos and more torpedos means bigger chance some of them will survive to score a hit. Size requirements/bigger is better I already mentioned specialized weapon that wouldn't fit small submarine but there would be other things that can have minimum size requirements- power source (nuclear reactor), engine, detection (special radar, sonar), defencive devices (energy field generator), communications (special long range radio) etc. Bigger submarine would mean more room for stuff like supplies that would mean longer operating range. Or more people like marine detachment for doing and defending against boarding actions. Bigger submarine could also support improved versions of things like thicker armor. Carrier Today the biggest military ships are aircraft carriers so maybe submarine version of those. They can carry normal planes or small strike subs. ]
[Question] [ One of the deadliest species of dragon is the dreaded Marksman Dragon. This beast has immense physical power and a bad temper, but its most potent weapon is its breath. The Marksman Dragon can shoot incredibly hot fire at very high pressure over long distance with pinpoint accuracy. Its fire is so hot and is shot with such force that it can cut/melt through solid steel plates from 10 yards away, and can cause grievous bodily harm at more than 25 yards from the pressure alone. The fire is far hotter than most other dragons’ and is fired as a narrow, cohesive beam that stays together over long range. Add to that the dragon’s incredible accuracy and you have one of the most dangerous beasts around. Sounds cool right? But I have a problem. How does this dragon create and propel such a hot, high pressure, cohesive stream of fire? I would prefer this dragon’s fire to not be liquid or gel based, however I am open to all answers. [Answer] Thermite is hot. Like CRAZY hot. In afghanistan I once dropped a thermite grenade on top of a captured vehicle's engine block. (Think a road flare the size of a coke can but WAAAAAY hotter). That thing chewed its way clear through a cast iron engine block and began busily charring its way into the ground underneath. The radiant heat alone ignited the tires of the truck as it was boring into the sand. Maybe instead of a "beam" I think you could have your marksmen dragon kinda cough a slug of thermite that is ignited shortly after it exits the dragons body by the dragon's normal fire. Maybe your marksmen dragons are a behaviorally unique sub-species of regular dragons that live in a region with a lot of iron oxide and maybe some sort of naturally occurring aluminum deposits. They eat the iron oxide and aluminum and store it in a crop kinda like a bird where its formed into wads of thermite that is kept inert via a coating of mucus that isolates it from oxygen. When the dragon wants to snipe somebody in the face with a tennis ball sized slug of white hot ravening death it coughs up one of these thermite wads and spits them as hard as it can with a small burst of regular dragon flame to ignite the thermite slug in flight. Naturally occurring pure aluminum isn't found on earth because it normally combines with other elements to form various oxides and other compounds, but then again, dragons don't exist either so it wouldn't really need much detailed explanation in such a setting. Locals simply observe the dragons eating iron-rust and some unworkable mystical metallic stuff known as "dragons ore" or something. This mystical compound is only found in the far reaches of the wilderness where the dreaded marksman dragons live, and they guard the substance fiercely. Woe betide anyone foolish enough to try to obtain the substance. [Answer] Plasma Breath If you're looking for something quick, hot, and with pinpoint accuracy, look no further than good old plasma my friend. Instead of using weak dragon lungs to propel breath weapon, the illustrious Marksmen Dragon uses naturally evolved magnets (birds have magnets so why not dragons right?) to propel the burning plasma at the weaker dragons. How hot can you get? As long as the Marksman Dragon can get the energy, your dragon could breathe (is shoot more appropriate?) plasma at temperatures hotter than the sun. Even fulfills the cohesive beam requirement, here's a simple google image search for plasma jet [![](https://i.stack.imgur.com/v62Jr.jpg)](https://i.stack.imgur.com/v62Jr.jpg) If you watch the second video, the scientists can only shoot plasma around 2 feet. To the Marksman Dragon, range is definitely a status symbol. Your dragons might have drastically smaller ranges while young thus making the Marksman Dragon a much more parental dragon over the conventional dragon that doesn't typically need to shoot far. Or maybe the gift of "LongShot", as the Marksman Dragons call it, is a genetic trait that is sexually selected for. Video Example <https://youtu.be/dvrQciFL0ig> More in Depth Video of some science behind <http://www.military.com/video/off-duty/tech/new-progress-on-plasma-weapons/2324951333001> [Answer] Looking at flametanks, archerfish and Brachininae a liquid seems like the best option. It is rather precise, can cover high distances, can produce hot flames. If you want an explosion at your target like an explosive round would do just shoot two different liquids that ignite when mixed together either instantly or when hitting a hard surface. [Answer] The Breath Shoots Bullets The common misconception with dragons is that they breath fire, I read somewhere (forget the source sorry) is that it’s not the case, well not what you think anyway. Dragons eat a lot of plant/animals matter to digest in their stomachs. they even eat minerals found in rocks (that's why they live in caves) to produce a napalm like substance then when attacked or attacking they move the substance to the back of their throat (looks like they take a breath) then fire it out of a gland under the tongue with two flint clickers next to the gland it ignites the substance, just like your lighter you get your breathing fire. so with that in mind have your dragon have another organ under the tongue that placers a tooth like projectile inside the gland and have the flint igniters behind the gland it builds up pressure then fires the projectile at very high speed and force not your beam canon that you’re talking about but still very effective. If you want you can add magnesium into the mix to get your heat. So your Dragon really is the Marksman Dragon. [Answer] The dragon has evolved incredible pressure-vessel technology within its body. Part of its fire-organ can be used to generate its fuel by secreting fat/kerogen, then compressing it until it chemically recombines into combustible hydrocarbons. I think it should do this compression over some period of time, under extreme enough conditions that most of the fire secretion is made up of a very thick slurry of bunker-oil tar fractions mixed with solid coal precipitate & very little lighter diesel fractions. The fire secretion is forced through a narrow aperture under staggeringly high pressures (probably comparable to an industrial water-jet cutter). Since the secretion has a consistency like pitch, the massive force necessary to drive it as a high speed liquid stream will heat it well above its auto ignition temperature, & it will come out as a deadly piercing beam of fire. The pressure will also ensure that it atomizes into the air effectively, so temperatures should be about as high as a charcoal & forced air metal forging furnace, & grains of burning carbon increase its ablative effect on materials the dragon wants to incinerate! [Answer] If you really want it to use a gas instead of a liquid or gel there are two ideas that come to mind: The first is a vortex cannon. Basically like blowing a smoke ring, only at a much higher velocity. <https://www.youtube.com/watch?v=BuH-hWrjZmw> has some cool demonstration shots. The kind of accuracy you're wanting would be a bit of a stretch, but possibly doable for a creature that was really good at judging the air currents on the path to the target. It would, of course, have to blow a lot of fire rings at a rapid rate to melt steel, but that's also potentially possible. Much easier with a liquid though as that would transfer the heat much better. Steel has to get really hot to melt. The other possibility is a bit more speculative. I remember reading about ten years ago about some research on beams of ultrasound, specifically that sufficiently powerful beams of high-frequency sound in air decay in a pattern which causes the circumfrence of the beam's distortions of the air to create a low pressure area in the interior of the beam that keeps it much more coherent than would otherwise be expected for a directional sound impulse moving through the air. The researchers were hoping to be able to use the phenomenon to allow for "surround sound" systems using only one set of speakers and encapsulating the rear sound in an ultrasonic conduit that would be disrupted upon hitting the back wall making the sound seem to come from behind the audience. This is quite speculative for a breath weapon because I don't know if the low pressure zone created would be sufficient to contain a propagating gas, but if it could be made so then it could be used to deliver your dragon's breath weapon with the kind of accuracy you are describing, and the ultrasound itself would add a not-insignificant amount of energy to the mix as well. I suspect, sadly, that producing a sustained beam of ultrasound at the required power levels would be beyond most biological or, indeed, mechanical systems currently in existence. But if you don't mind a little bit of magic or hand-wavium it would be workable for a story. And if your world includes magic along with the dragons it would allow some innovative uses of any "silence" type spells. [Answer] This is common misconception about the marksman dragon, which in fact does not exhale flames and instead launches a chemically unstable pellet derived from their foods (think similar to an owl's digestion) that due to it's unstable nature reacts in a hugely exothermic reaction when exposed to oxygen. This pellet sticks to surfaces as it quickly reaches over 2000 degrees Celcius, plenty hot enough to cause the surface to combust. The misconception is so common due to the fact that once the dragon begins launching these pellets it's digestive tract is unblocked (again think similar to an owl) and it begins feasting on everything nearby, leaving only those at a distance, who would see the dark silhouette of the dragon hovering in the midst of the spreading flames, to report the dragon. [Answer] You may want to check out the How to Train Your Dragon canon, as the [Night Fury](http://howtotrainyourdragon.wikia.com/wiki/Night_Fury) seems extremely similar to what you are looking for. [Answer] Gun dragon Your dragon takes a rock between his teeth, heats it up with his flame and then using a explosion inside his mouth spits the stone over greater distances, than normally possible. This means that he has oxygen as part of his dragon breath fuel, so that it can explode in a somewhat sealed space. Beetle dragon This dragon is a "black sheep". He can not breathe fire, but he can spit hot acid like this [thing](https://en.wikipedia.org/wiki/Bombardier_beetle). Other dragons hate him, because his attacks completely ignore their fire resistance, they were building for milleania. Worm dragon This dragon didn't like the others much, but he became a friend with a strange [worm](https://en.wikipedia.org/wiki/Mongolian_death_worm) from a desert. This sand worm taught him to how to make lightning come out of his face. Now they eat horses in Mongolia together. ]
[Question] [ I was wondering, there's something that keeps me asking myself in Star Wars and other SF universes. Many S-F universe use "vintage" or "crappy" or "old-fashioned" designs for robots. Like C3PO & R2 units in Star Wars or Fallout or even in the Asimov's Cycle of Robots. Non-humanoid robots are described or look like big rolling trash bins. Is there a reason why we could think it'll be like this ? Is there any rational reason (like economic reason ? Development of recycling ?) [Answer] Three reasons: * They're characters * They're easy to make into toys * They're easy to make into props/models/fit actors into If you ask this on the Sci-Fi & Fantasy community, you'll get a reasonable in-universe answer. But the truth is, that they're just characters and robots being exactly fit for purpose would be relatively boring to watch/play with. [Answer] Please bear in mind that I've only seen the movies - and not often at that - but I think they offer some good reasons for the design choices. ## R2D2 R2 was at some point in one of the original movies picked up by some kind of crane dealie (the technical term, I'm sure) and placed into the pack of Luke's x-wing. It seems like, for whatever reason, it was desirable to have a component of the plane that could leave the ship, take instructions, and be lifted into another ship. With those requirements you could really make R2 any shape you like, but something very sturdy and unlikely to fall down seems like a good choice. Using limbs or treads would probably complicate the "installation" procedure. [![R2D2, installed](https://i.stack.imgur.com/06I14.jpg)](https://i.stack.imgur.com/06I14.jpg) ## C3PO C3PO was built by a child - no further design justification needed. Frankly C3PO's lucky he didn't end up looking like a toaster with wires sticking out of it for no good purpose, as my attempts did when I was younger. His construction was actually criticized by others at the time, when in one of the newer movies he was told he was "naked" because he didn't have a proper outer shell yet. I assume he had one made later that fit the way his skeleton was put together. [Answer] Depends by what you mean by 'crappy' Human form factors suck. Walkers are pretty darned inefficient. Lets consider the trash bin form factor. For example one of these [![enter image description here](https://i.stack.imgur.com/et1dz.png)](https://i.stack.imgur.com/et1dz.png) No actually, one of these [![enter image description here](https://i.stack.imgur.com/8xt3mm.jpg)](https://i.stack.imgur.com/8xt3mm.jpg) Your sensors can swivel 360 degrees You have stability (since you have 3 points on the ground) on a smaller, more flexible setup than a 4 wheeler. Its uniquely suited to fit into a standard recepticle, which is compatible with other models like the R5 and BB series. Of course, they also sometimes had to climb out, in the middle of a gunfight, and r2 got hit a few times. Oh, and did you know you could fit a little person inside one? Lets consider a few more robot designs the mouse droid or K9 from dr who. Box with wheels. Cheap, simple. Completely baffled by stairs. [![enter image description here](https://i.stack.imgur.com/Mz9Bw.jpg)](https://i.stack.imgur.com/Mz9Bw.jpg) Also gets no respect. [![enter image description here](https://i.stack.imgur.com/LVQag.jpg)](https://i.stack.imgur.com/LVQag.jpg) Wall-e. Adorable little cannibal trash compactor. Designed for his environment, though those arms... are a little odd. He is though a good basic design for a mobile, sentient trash compactor. Practical threads. simple box design In a sense though form follows function On the other hand, I like my industrial robots like I like my prison furniture. Firmly bolted to the ground. I suppose you could put them on rails, or maybe wheels, but why does my industrial equipment need to walk off and bother the local wildlife? There's a good reason modern robots are just arms [![enter image description here](https://i.stack.imgur.com/IjY3J.jpg)](https://i.stack.imgur.com/IjY3J.jpg) You have a basic range of motion similar to an arm but entirely suited to the task. Swappable functional ends. r2 is adorable. A robot arm on the back of your X wing could shoot back, swap its working end from a gun to a fire extinguisher and put out a fire. Then switch to a tool to pull out a dead engine, put in a spare, and throw the dead engine at a tie fighter. Assuming you had a spare engine. Or an r2 droid. [Answer] It's interesting that you ask this, I was just thinking of my Roomba and why it is now obvious why it is round. Wheel motion would be difficult if it was any other shape rather than round. I mean when the Roomba needs to navigate it goes forward, stops, spins in the new direction and then continues. If it had corners its programing would have to use the center to the farthest corner as the diameter of its spin circle. The next reason is that we as human designers prefer things to look nice from our point of view. Therefore, cars in the 60s had fins and in the 40s were art-deco, etc. Each decade has its own type of design. When I see Star Wars, even Rogue One, I think, boy is that from the 70s! My conclusion is that it is human nature that things are designed more to reflect aesthetics rather than function. A quick look at my desk shows me that. For example does my desk phone need to be that big? Does the handset need to have a lead weight in it? Do my monitors really need blue lights on the power button? [Answer] In general the look of technology is inspired by real world things, either contemporary or historic, often designers will mix a number of elements to evoke the look and feel which is required for the production. I actually think that the design aesthetic of the original trilogy has stood up pretty well. One reason for this is that they went for a fairly grimy and industrial look which, in the real world tends to be dictated by practicality rather than fashion and so it remains reasonably relatable. With any form of design it is extremely difficult to come up with something which is totally original and innovative, especially at the sort of short notice required for film and TV design and entirely impossible to reliably guess what technology far in advance the current would really look like and sci-fi designers have, in the past got things remarkably right but also very wrong. There is also a phenomenon in robot design known as the [uncanny valley](https://en.wikipedia.org/wiki/Uncanny_valley) this is where artificial things which look a lot but not exactly like a person make people quiet uncomfortable. Which has led some robot designers to speculate that consumer robots in the future would be better looking like robots rather than attempting to mimic people, if only from a marketing and user interface perspective. Looking at the star wars examples in question. R2D2 is apparently a versatile (some would say a bit too versatile for the sake of plot convenience) utilitarian robot whose main function seems to be the maintenance of other machines. In this context a short cylindrical body with small wheels and limited ability to 'walk' makes reasonable sense for something which is intended to mostly move around on flat surfaces and is exactly the sort of thing you would expect to see on a factory floor. Indeed a lot of real world mobile industrial equipment like diagnostic stations and [welding equipment](http://www.r-techwelding.co.uk/mig-welder-inverter-with-mma-dc-tig-swfu-415v-450a/) have a very similar form factor [Answer] Walkers are computationally expensive and relatively slow. Looking at the real life example of [BigDog](https://en.wikipedia.org/wiki/BigDog) helps provide us with context. > > BigDog was funded by the Defense Advanced Research Projects Agency > (DARPA) in the hopes that it will be able to serve as a robotic pack > mule to accompany soldiers in terrain too rough for conventional > vehicles. Instead of wheels or treads, BigDog uses four legs for > movement, allowing it to move across surfaces that would defeat > wheels. > > > A robot with wheels may be more energy efficient, durable, and perhaps most importantly: fast. Because they require far less computing power they also can be much smaller. Robots who can zip about inside space ships and urban environments at high speed with wheels don't need to be particularly futuristic. They can afford to be a bit boxy, and perhaps more like a toy radio controlled monster truck with good suspension and ground clearance. Another possibility is that someone devises antigravity. So they are capable of floating across obstacles, then returning to a wheeled mode for higher speed (assuming antigravity is energy intensive too). A robocheetah may be cool, but it's pretty much design overkill when you could have a comically fast miniature jawa sandcrawler instead to fetch mail/lunch/coffee. [Answer] well let's look at the droids. One is a mobile navigational computer/repair drone, which means you want it cheap (aka replaceable) and compact. and a little wheeled trash can is both, making it walk would be a lot of extra cost for no real gain. The other is built to facilitate humanoid communication which means it has to be human shaped, but it was also built by a slave from spare parts so it's not exactly the most versatile of machines. The combat droids are built to be both cheap as possible and exploit existing military infrastructure so a simplistic humanoid shape makes sense. The all seem to make sense. [Answer] For the same reason almost all non-human characters in sci-fi and fantasy are bipedal and human-shaped - because that's the shape of the person inside the suit. The simplest limit in making a film is the question of how you make that thing move. Ray Harryhausen and his colleagues were the first step in moving past those limitations. Harryhausen's skeleton army is still pretty damn amazing even today, when our standards of FX are considerably higher. Back in the day, it must have been mindblowing. Stop-motion is clearly the predecessor of modern CGI creatures, because it allows any creature to be animated which the creature can imagine, with no real physical limitations to the creature or to how it moves. There were plenty of interesting side-quests via physical puppetry though. Jabba the Hutt, in RotJ, was a physical creation with several people operating it. Most amazingly, I *strongly* suggest you watch the director's cut of Aliens and how they filmed the Queen versus Powerlifter fight - yes, that is genuinely a 15-foot structure that Sigourney Weaver is standing in, and yes, that is genuinely a 15-foot fully-detailed alien, and yes, they are genuinely pacing round each other and lunging at each other. The director's cut has a significantly extended fight with several long cuts, which makes it even more mindblowing. Each one is basically operated by a team of weightlifters, but so skillfully operated and so well shot that it's utterly compelling. As impressive as all this is though, essentially it's a dead end. If you want realistic non-humanoids, of any description including robotic, and there are compelling reasons for them to be actually non-humanoid, then anything involving a human is a non-starter. In that case CGI or good physical FX without a human inside (BB-8, for instance) are the way forward. In the original Terminator, the "hunter-killers" were tanks or aircraft, which completely made sense. The Cylons (BSG) are an interesting counter-example though. They're CGI, but CGI of a humanoid robot. If they were simply a tracked weapons platform then they'd be much more effective as a weapons platform, but the plot requires them to be scary. Uncanny Valley makes something scary if it looks a bit like us but clearly is not like us. (And of course there's the 70s TV series, where the Cylons are just men in robot suits, which limits expectations.) So in spite of the physical possibility of making Cylons a devastating weapons platform of any shape they chose, narrative requirements mean they're just another humanoid. [Answer] Just think of R2-D2 as an intelligent rolling toolbox. Say you were to design a robot to work in a mechanics shop you might go for a similar design. You would want it as small as possible but large enough to carry all the tools and diagnostic equipment needed. Waist high or counter height seems about right, although I might put some type of flat surface on top instead of a round dome. The round shape allows maximum internal volume and access to tools, considering that I don't know the exact internal configuration of components it is conceivable to think of part of the internal layout as some type of a tool carrousel that rotates around the interior. Mobility with two rolling legs seems reasonable with the optional stability of a third tripod configuration also seems like a good idea. So maybe you wouldn't end up with something just like R2-D2 but it might be very close. ]
[Question] [ Scenario: The [ESA](http://en.wikipedia.org/wiki/European_Space_Agency) wants to get more respect and more funding. Last time they were thinking about [faking the Mars landing](https://worldbuilding.stackexchange.com/questions/22934/cheapest-way-to-fake-the-mars-landing), but after some discussion they reached the consensus that they cannot fake Mars landing. Instead, they decide to fake Martians but for doing it for real, we need more money and to join forces with NASA, even if we kinda [hate NASA](https://worldbuilding.stackexchange.com/q/22573/2071). The question: What is the cheapest way to fake intelligent life on Mars? I think "finding" some underground life is beyond plausibility. But what if some alien "crashed" on Mars and started living a [Martian](http://en.wikipedia.org/wiki/The_Martian_(Weir_novel)) life on Mars? That would definitely boost NASA's and the ESA's budgets to the roof! But ... can we fake it? And if yes, can we fake it until a manned mission to Mars is launched? And can we do it cheaply? Please note: People cooperating on this plan is again one big hand-wave. Please try focusing on the monetary aspect. But again, I may give some additional points for an elaborate guess on how much money and people I need to pull this off. [Answer] Yes, you can fake a land with existing rovers but you won't want to. The following sequence of events will establish the hoax but you'll never be able to keep the secret for long and when the hoax is revealed, ESA and NASA reputation will be tarnished forever. 1. Have [Curiosity Rover's sensors](http://mars.nasa.gov/msl/mission/instruments/environsensors/rems/) register a significant overpressure event followed by several more smaller events over the next couple of hours. 2. Register massively increased radiation readings from the [RAD](http://mars.nasa.gov/msl/mission/instruments/radiationdetectors/rad/) and [DAN](http://mars.nasa.gov/msl/mission/instruments/radiationdetectors/dan/) sensors. Between the overpressure events and increased radiation it is easy to show that a large explosion took place that involves some kind of nuclear power source. 3. Release these findings to the world and watch them go nuts. 4. The world is going to demand further information about this. Immediately. Every telescope, radio telescope, amateur telescope will be pointed towards the Red Planet. Any orbiter around the planet will be ordered to look in the vicinity of the Curiosity Rover to see what's happened. The resolution of such probes is sufficient to identify sub-meter objects on Mars surface. The probes that can see Curiosity are owned by NASA or ESA. 5. Curiosity will be ordered to start looking for the source of the radiation so a long string of increased radiation reading will need to be faked in order to show progress towards the crash site. 6. To avoid having to actually show the alien wreckage, have the radiation readings approach Curiosity's maximum radiation threshold so that to continue will endanger Curiosity's survival. If ordered to continue anyway, secretly shutdown Curiosity before any photographs/videos of the crash can be sent back. ## Repercussions It will be incredibly easy to fake an alien crash on Mars. It will be impossible to keep the hoax a secret for more than a few years before every space agency on the planet sends missions to figure out what happened. Life on Mars is THE discovery in world history. Astronomers have been talking about life on Mars since at least 1858 with the "discovery" of the [Martian Canals](https://en.wikipedia.org/wiki/Martian_canal). India has a Mars orbiter as of September 2014 (and they got it there cheaply). With the advent of this hoax, funding for Mars missions have now become effectively unlimited as the demand for information about the event now surpasses the Space Race of the 1960s. In the short term, ESA has gotten what it wanted, massively increased funding. In the long term, ESA and NASA are finished. All research they have ever done will be called into question. Many many people will lose their jobs and be permanently blacklisted from the science community. In short, don't do it. The short term gains aren't worth the long-term losses. [Answer] *I'll be an optimist here, and say that maybe - just maybe* - it can be done.** Here's my plan: 1. Send a rover to Mars - or, rather, wait until a rover gets sent to Mars. The best choice now is to wait for the [Mars 2020 rover](http://mars.jpl.nasa.gov/mars2020/mission/overview/) to launch. 2. When the rover lands, begin its mission planning. It will hopefully bring back some positive results regarding Martian habitability. 3. A few months in, begin a planned "disaster". The rover will suddenly stop broadcasting to Earth, and all attempts at communication will be in vain. Build up press excitement about the cause of the failure. 4. Let the rover bury a small box containing a radio transmitter, that periodically sends a message to Earth. [It could use mathematics.](https://worldbuilding.stackexchange.com/questions/22882/is-mathematics-a-truly-universal-language?lq=1) 5. Drive the rover away from the burial spot, and then "wake it up". 6. Create a detailed press release saying that some interference caused a transmission error in the rover's instruments - somehow, another signal was being sent on the same frequency, and there was a mistake. Announce that the communications have been modified, and the rover is searching for the source of the other signal. 7. Follow the trail to the spot, but go a different way. There's one problem here, which is that there will be tracks from the rover as it left from the burial. Disguise those somehow, or wipe them off. 8. Dig up the box - clearly alien in nature - which continuously transmits a radio signal. Amplify the signal, and send it back to Earth. Make sure that everyone can receive the signal. Have someone - not necessarily affiliated with NASA/ESA decipher it. 9. Have the box "accidentally" self destruct after the rover leaves it behind, for fear of contamination of its instruments. There is no physical evidence. Yes, you will need people to complete the mission. You'll need a small team to make the box, although that number can be slimmed down. Hide it in the rover as a classified attachment to an instrument that is never talked about. You'll also need another team to pre-program the rover to do the maneuvers on its own. That should be it, though. It's cheap and requires very few people to pull it off. [Answer] Building on Green's answer, you would not want to fake Martians or aliens on Mars, because there would be far too many people in on the deception, and someone will talk (remember: two can keep a secret when one of them is dead....), and even in the unlikely event that not one of the thousands of people in the ESA or NASA spills, the Russians, Chinese, Indians and even interested private citizens with Jeff Bezos or Elon Musk sized bankrolls will be on the way to investigate (Bezos and Musk, of course, own their own rocket companies which can do the job). As well, you should remember that there needs to be an element of plausibility. The "Face on Mars" has spawned a cottage industry and Richard Hoagland is constantly pushing ever more elaborate explanations on his website; but he is justly viewed as a crank. No one is going to spend more than a pittance on that (and then mostly to debunk it). What is really needed is the right combination of indeterminate results that constantly tweak people's interest, and the "right" people who are both interested and motivated to do something about it. We actually have more than enough "indeterminate" findings dating back to the Viking landers in 1976. There are indications of water, changes to the atmosphere like anomalous whiffs of methane, possible microfossils embedded in Martian meteorites and even the somewhat inconclusive results of the Viking lander's on board lab. Taken individually or even together there is no conclusive proof of life, but neither do they make a convincing argument against life on Mars. The ambiguity suggests that something rather strange is going on there, and that our current science is not able to figure it out (not enough data points). So the missing ingredient is someone to pull it all together and motivate enough people, politicians and bureaucrats into supporting a full bore Martian expedition capable of doing a detailed study of Mars and developing enough data points to actually answer the question. This individual needs to be well informed enough to talk sensibly about the issue, have plenty of connections in the scientific and political community and have "rock star" charisma to convince even the most sceptical person (since the vast majority of people are more easily swayed by emotion rather than rational thinking. Consider that the next time there is an election in your city, State/Province or nation). This needs to be a very exceptional person indeed, since calls for a Martian Expedition have been going out since the 1950's (Wernher von Braun wrote a detailed proposal known as Das Marsprojekt in @ 1957), and you can count people as varied as Arthur C Clarke, Carl Sagan, Robert Zubrin and Elon Musk (among others) as all having been proponents of Martian exploration. Since the Return on Investment (RoI) for space exploration and industrialization has been relatively low (virtually the only things in space that pay for themselves are communications and observation satellites), few governments or corporations are inclined to spend more than a pittance on space (to the point that the Americans knowingly abandoned their independent ability to send astronauts into orbit and the Russians allowed a factory with two Buran orbiters to be abandoned while the hanger holding the third suffered a roof collapse, crushing the only flying version of the orbiter <http://www.timetobreak.com/1242311/30-unseen-photographs-of-an-abandoned-russian-space-program/>). Perhaps if an "A" list movie star or a real Rock Star were to begin speaking positively about Martian exploration, that would be enough to build a movement to go to Mars, since nothing else has worked to date. [Answer] # Denounce your own hoax. People on the Internet are all the time "discovering" things in the probe images and videos. All you need to do is leave something clearly anomalous - say a rough figurine of a hand with four fingers, or anything equally unlikely - where the probe will photograph it. Then dub the thing something funny - "the Shrub" - and proceed ignoring it. After a little while, maybe with a gentle prodding, but more likely all by themselves, people will start talking about the Martian Hand. Point out that it can't possibly be an artifact, because: * there are no Martians. * pareidoly is a sufficient explanation for the object's resemblance to a hand. * it doesn't even resemble a hand all that much. * and, obviously, there are no Martians and never were. * it is unlikely, to say the least, for the probe to have landed near such an artifact, unless Mars is covered with them, which we know it isn't. * the "possibly inhabited" surface of Mars is down several feet of dust in that area. Even if someone had left an artifact back in the day, it would be buried deep, not below a few millimeters of sand, ready to be churned out by the probe's wheels. * and -- someone who? There are no Martians! After several weeks of trolling, grudgingly agree to go back to the Shrub to perform some analyses, even if it's clearly any old rock. But the artifact is no longer there. No, wait, it is. The old pictures were mislabeled. Sorry for all the excitement, guys. Anyway it's just any old rock. We're drilling now. Silence descends. Several technicians and analysts that aren't part of the very small clique that prepared the hoax go ballistic and are silenced - the readings make no sense. You patiently explain to them that before going public with anything, given the sensitivity of the situation, many more tests need to be performed. After all, there are no Martians, so the artifact cannot be made of fired clay and cannot contain the organics the analyses show. There must be some simple explanation and we don't want to go the conspiracy route. After a couple of days outside people start asking, and pestering personnel to know what's going on. Delay. The results will leak anyway. Several analyses later you convene an internal, secret meeting and explain that the analyses say that the object is artificial. But since there are no Martians and all the previous objections still stand, it must be investigated whether the object could not have been brought from Earth - namely, in the probe. So, a panel of three experts (all members of the conspiracy) is nominated to determine the exact path and provenance of every single bit of the probe. The whole personnel is requested to keep the whole thing as secret as possible, thus ensuring that everything is leaked to the major media channels within one hour. The world predictably goes mad. Your obdurate refusal to admit the object is Martian makes you an Internet meme. A cartoon with the ESA's spokespersons mashed in a lion's mouth while confidently declaring "See? There are no lions! This is just pareidoly and wishful thinking!" makes the cover of Time. Your panel comes out with possible ways someone might have smuggled the artifact all the way to Mars, each more farfetched than the last (one of them is true, though), and gets lampooned and ridiculed. The panel leader gets interviewed and describes the wildly improbable way someone might have equipped the probe with the Martian Hand and devised a way of deploying it on command. > > Q. "And could all this have been done without anyone noticing?" > > > A. "Well, nobody would expect anyone to try such a stunt, so-" > > > Q. "You mean that I could enter ESA's labs and add a little something to your next probe, just like that?" > > > A. "No, no, of course not! But, well - perhaps - if you had collaborators inside -" > > > Q. "Professor, I took the liberty of asking your colleagues how this could be accomplished. Apparently you'd need the collaboration of nearly everyone. The probe has been weighted, shaken, tested, disassembled and reassembled several times, as you very well know. Its weight is known and the artifact doesn't appear on the manifest." > > > A. "The weight has some tolerances that -" > > > Q. "That would have sent the mission anywhere but Mars. That weight must be accounted for in terms of fuel, again as you very well know." > > > A. "When the impossible has been ruled out, what remains -" > > > Q. "Ah, but who says that the Martian Hand is impossible? Is it not true, Professor, that you're a lifelong member of several 'skeptic' associations who staunchly deny the existence of extraterrestrial life?" > > > A. "We claim nothing of the sort! It's simply that there's no proof that-" > > > Q. "And now the proof might be here, and you won't accept it because you never had proof before? How do we prime this pump, Professor? Somewhere we'll have to start accepting proofs, won't we?" > > > As a nice touch, two "investigators" are denounced as declaring to be willing to fake smuggling the Martian Hand and accusing themselves, before allowing this farce to go further. After that, any clue suggesting that the Martian Hand might actually have been smuggled is automatically suspect. The last line of defense of the Hand Skeptics is "If that's a hand, well then where is everything else? Where is the arm, but more - where are the ruins, the streets, the whatever else a civilization must have left behind? You really want us to believe that there's only a hand left, and that by chance we happened right smack on top of it? Come on!" At that point, a grassroot movement emerges claiming for a manned mission to Mars armed with shovels. [Answer] # Short answer: you can't. ## Long answer: [![enter image description here](https://i.stack.imgur.com/FHKlV.jpg)](https://i.stack.imgur.com/FHKlV.jpg) [Curiosity Spotted on Parachute by Orbiter](http://www.nasa.gov/mission_pages/msl/multimedia/pia15980.html), www.nasa.gov The [Mars Reconnaissance Orbiter](https://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter) (MRO) is a US-owned and operated satellite currently orbiting Mars. It carries a 50-centimeter telescope called [HiRISE](https://en.wikipedia.org/wiki/HiRISE). MRO's 250-by-316-kilometer sun-synchronous polar orbit gives HiRISE a resolution of about 0.3 meters across nearly the entire surface of Mars. Just to demonstrate HiRISE's resolving power, the above image (taken by HiRISE) shows the [Curiosity rover](https://en.wikipedia.org/wiki/Curiosity_(rover)) descending on its parachute. HiRISE is even capable of resolving details on the rover itself: [![enter image description here](https://i.stack.imgur.com/Wctv9.jpg)](https://i.stack.imgur.com/Wctv9.jpg) [Mars Orbiter Images Rover and Tracks in Gale Crater](https://www.nasa.gov/jpl/mro/curiosity-tracks-20140109/#.VdqXbrJVhBc), www.nasa.gov If the ESA wants to fake a crash-landing on Mars they must first explain why the ship, and more importantly the crater it made, are only detectable by [Mars Express](https://en.wikipedia.org/wiki/Mars_Express). --- I know your next thought is to intercept and modify MRO's telemetry. Unfortunately all of the [DSN](https://en.wikipedia.org/wiki/NASA_Deep_Space_Network) antennas used to communicate with the orbiter are under physical control of the US government, and two of them are not in ESA member states. In order to alter MRO's data, the EU would have to mount one of the most sophisticated cyberattacks ever conceived against the world's most paranoid nation (who is also one of the two world superpowers in cybersecurity), and remain undetected for years under heavy and immediate scrutiny from the engineers who designed and built the instruments and the scientists who have been analyzing data from them for a decade. In short, impossible. --- Even if you think this is achievable, you have to do it twice: India's [Mars Orbiter Mission](https://en.wikipedia.org/wiki/Mars_Orbiter_Mission) has a resolution high enough to see a the crater that would be left, and the instruments to verify Mars Express' "detection." MOM communicates via [India's own IDSN network](https://en.wikipedia.org/wiki/Indian_Deep_Space_Network), which is physically located in India. # Also: you wouldn't want to. > > ESA wants to get more respect and more funding. > > > As others have mentioned, when ESA eventually comes up empty-handed and their deception is revealed, they will have neither respect nor funding, and end up a disgrace not only to the EU but to the entire scientific community. My advice is therefore don't even try. [Answer] Here's what you can do to generate interest and funding, without damaging future funding prospects, instead of intelligent life, say that you've found evidence of microorganism life. Say that the soil activity is more than what you'd expect from non organic soil, and you need to send a second mission to bring the tools needed to verify the findings of the first probe. Publish blurry images, enough to generate interest, but not enough for independent third parties to do proper scrutiny. Once you've got the funding you needed, you can evade the questioning by claiming that the evidence of microorganism turns out to be contamination from earth microorganism. You can milk even more funding by generating interest for these questions, you'll need even more advanced tools to verify that these microorganisms aren't actually earth born. It will be really hard to proof your wrong doing. [Answer] I'd go with an artifact in the soil - anything big is obvious, and would seem a massive coincidence if you e.g. had an explosion after you sent your probe, but none before despite it being under observation for a good long time. So you need something that only your probe could have discovered, wouldn't be susceptible to observation, and makes 'intelligent life' the only explanation. So - a 'pottery shard' is clearly the answer - these are found all the time on earth, and it's not actually all that uncommon to find pieces that are hundreds of years old. Something made out of a close approximation of martian materials, but in concentrations and formations that cannot be naturally occurring - pottery is clay that's shaped, painted, glazed and kiln fired. Would need to make it so that's it's plausibly 'made on mars' e.g. in terms of radioisotopes, materials, etc. And then just 'hide' it in the rover, to be 'discovered' by one of the digging elements when you look at an interesting rock formation. The fabrication is pretty cheap, comparatively (although, you might need to figure out how it's made given not much water being available). You don't have the advanced carbon dating mechanisms that you would have on earth which is a really good way of proving fakery. And a pottery shard - especially with a pattern on it - is clear signs of intelligent life at some point. (I am of course, leaving aside the other reasons not to do this, which other questions have covered quite well). ]
[Question] [ In a medieval society, an ethnic group lives most of their lives aboard airships. These airships are rudimentary, perhaps holding only enough room for a single family. They consist of slender wooden hulls, large bags of hydrogen for lift, and leather wings for shifting trajectory. Due to the lack of propellers, they generally follow prevailing winds. However, a significant issue with this lifestyle presents itself: food. What organisms and techniques could these people use to create a nomadic society amongst their airships? Please keep the technology around medieval levels. [Answer] # Hunting birds bring nearby food sources back to the airships * Falcons for migrating birds * Cormorants for fish Falconry is a Eurasian hunting method dating from [the 13th Century BCE](https://www.britannica.com/sports/falconry) and well into the [Late Medieval Period c. 1500 CE](https://www.youtube.com/watch?v=YFuG1ddWl8Y&ab_channel=HistoricRoyalPalaces). The falcons fly out to catch small game and bring it back to the handler. In your scenario, each airship has one or more of these birds, which are trained to retrieve migrating birds as they pass nearby and bring them to the airships. I believe a reasonable active range is at least 0.6 mile / 1 km away from a handler in calm conditions (having observed this myself at falconry displays). Consider the traditional Chinese cormorant fishing rafts, where the fisher and the birds have a symbiotic relationship; the cormorant eats a portion of the total catch as "reward" for helping the fisher. In fact if you add buoyancy controls to your airships, then they could even descend to near sea-level and allow actual cormorants to fish for them. ![Chinese man with cormorants](https://cdn.theculturetrip.com/wp-content/uploads/2017/04/shutterstock_309510137_.jpg) Image source: <https://theculturetrip.com/asia/china/articles/the-history-behind-the-cormorant-fishermen-of-erhai-lake/> [Answer] > > However, a significant issue with this lifestyle presents itself: food. > > > I like airships as much as the next person[1], but all the numbers involved in them are against your medieval society. Especially if "pastoral" and "nomadic" implies "poor", as shepherds traditionally are. Estimate a person at 150lbs, then a family of four are 600lbs. Add all the trappings of airship and life (gondola, gas bags, ropes, clothes, tools, water, some leeway, etc) and call it a minimum of 1,000lbs that needs to be lifted (I suspect I am erring on the low side). The Hindenburg could lift ~500,000 lbs (including its own mass). It took 250,000 dead cow intestines to make the lift bags for it. By my conveniently estimated numbers your airships need to be at least 1/500th of a Hindenburg. Balloons ~6.5 meters long, 8 meters wide, 8 meters high, filled with 435 cubic meters of Hydrogen - 40 concrete mixer trucks sized. And will take 500 dead cows. Compare the [GoodYear Blimp](https://www.goodyear.eu/en_gb/consumer/why-goodyear/blimp.html) which has 10-20x more Helium lift gas: [![GoodYear blimp outside, seen while flying.](https://i.stack.imgur.com/IWoN6.jpg)](https://i.stack.imgur.com/IWoN6.jpg) and even that would confine the family to live in something like this size: [![GoodYear Blimp inside, small cabin and 8 seats pictured](https://i.stack.imgur.com/k5hqm.png)](https://i.stack.imgur.com/k5hqm.png) Compare also the [Airship America](https://www.airships.net/first-attempt-fly-atlantic-wellman-vaniman-airship-america/) built in 1905, his company had an investment of \$75,000 which is over \$2,000,000 in today's money accounting for inflation. Then he started to fundraise for the airship. [![Airship America over the Atlantic Ocean](https://i.stack.imgur.com/2vL0T.jpg)](https://i.stack.imgur.com/2vL0T.jpg) This airship is also bigger, but the cost is surely non-trivial. One idea you could take from The America is that wonderful equilibrator hanging down into the water. "Wellman and Vaniman’s idea was that as the airship lost lift at night, and settled toward the surface, the equilibrator would descend into the ocean; for every four feet the airship descended one gasoline tank would be lowered into the sea, reducing the airship’s load by 100 pounds and ultimately checking the ship’s descent. When the airship gained lift during the warmth of the day and began to rise, it would lift a number of the gasoline tanks into the air, increasing the ship’s load and thus checking its ascent.". Make them water bottles instead of fuel tanks, and you have a low-tech way to control the airship's height while also having a way to trawl for fish or a ladder up/down to ground level. If they drifted slowly over land, and this dragged on the land, people could go down to hunt and socialise and come back up. If they could be tied to several buffalo harnesses, those could drag the airships along with the herd and keep all the tribe together. --- > > However, a significant issue with this lifestyle presents itself: food. > > > Technology, boredom, exercise, dating and partying. It might matter - where do they get their Hydrogen from? (It wasn't even discovered for 200+ years after medieval times on our Earth). Are they going to make it with chemistry, trade for it, or obtain it from a natural source? Any one of those could be a reason to land. The lift bags? They might have to be partly ground-based to kill so many cows and process their intestines. That would give them plenty of time to preserve the meat for food. And as airship lift power goes up with gas volume, and volume goes up much faster than length and width, so adding a bit more size and a lot more volume would make it plausible to lift provisions long term. The site linked below[2] estimates that stockpiling enough food for a person for a year weighs about 500lbs. It could be arranged that if they can make a 1,000lb-lifter, they can make a 2,000lb-lifter and bring months of food with them. I think you could adjust these things with a bit of story telling license to make them able to preserve months of food at a time. They fly over the Great Plains, keep in contact with each other with long range signalling, every 6/9/12 months they all land together, hang out for a while killing and preserving salted buffalo and intestines, making repairs, trading, partying, then leave with enough food for another long time. They can collect seeds, tempt birds in and catch them. You haven't said why they have this lifestyle, in story terms. It must give them some benefit for the huge cost, effort, and risk involved. Is there something high up of great value? Do they make and sell maps? Capture animals which are naturally Hydrogen filled and flying high? Act as mercenary bomb-droppers for warring factions? Something like that could give them value to trade to get food from others. [1] or perhaps a little more; did you know the Graf Zeppelin was the first vehicle to fly a million miles? That it had asbestos roofing over the smoking room to protect the lift bags? That it was the first vehicle to fly to the North Pole? That it was a post sorting office and funded mostly by stamp collectors getting mail sent through it? That it used to brush against clouds to collect water to replenish the ballast tanks? That there were people in each of the engine compartments who had to manually adjust the speed in response to the Captain's orders? That Steinway made a lightweight Aluminium Grand Piano for the Zeppelin company? That the Hindenburg used sonar pings down to the ground to measure altitude? That they invented fuel the same density as air, so as they burned fuel and emptied the tanks, the ship didn't get lighter? That they [banned sausage making in Germany, Austria, Poland](https://www.theguardian.com/lifeandstyle/2013/aug/23/wurst-zeppelins-german-sausage) because they needed so many intestines for Zeppelin lift bags? [2] <https://preparednessadvice.com/how-much-food-do-you-need-for-a-year/> [Answer] ## Pastoralists Follow Herds Depending on the specific region of the aetherial seas you're looking at, Skyherd folk might follow any one of several great flockbeasts of the sky! In the warm lands of Irinsurea, skyherd folks follow after the air buffalo as they wander from current to current, wallowing in the warmdraughts of the midverticals. These creatures are a wonder to behold! Large puffy starfish shaped behemoths, their bodies are little larger than an ordinary water buffalo calf but it's the great hydrosacks that make them so impressive. Land dwellers fear the coming of the air buffalo herds, taking their sky darkening movements are ill omens of doom. And they're right to dread! Although the only serious threat the air buffalo ever really pose is a near constant rain of piss and a drizzle of watery poo. It is for this reason that the Curellians invented three kinds of brollies: the parasolelh, a nice, light & gaily coloured thing to provide a little shade on hot sunny days; the paraplueya, a sturdier device to ward off showers of rain; and the paramerda, to shield from the seasonal effluvium. In the drier climes of Phazzanea, the Windwardens hunt the riparhinoceros. This is a deadly beast, and no lazy floater! Bull riparrhinoceroi gallantly and bravely defend the rivers of air above the wafting grasslands below. Their long pointed nose horns seem like the sharp prows of a war galley, though in reality, they are more for display than for actual combat! Though occasionally a particularly rough display of prowess will cause the rupture of another beast's hydrosack! [Answer] # Aerial Trawling! [![Trawling Ship](https://i.stack.imgur.com/9U19Y.png)](https://i.stack.imgur.com/9U19Y.png) Your pastoral airships often pass over large bodies of water - many wind patters hug the coasts of continents. When they're feeling hungry, drop the nets! Trawling nets can catch huge amounts of fish and other sea creatures, and fish (unlike migratory animals) are almost always a reliable source of food year-round near the coastlines. Your airships gain a special advantage when choosing fish rich areas, the trawling will slow them down significantly, allowing them to linger over these areas for an extended period of time! [Answer] (Assuming your okay with altering the world slightly) add some animals in the surrounding area to eat. Like various birds(or just increase their numbers in the area to make it work). Or change a few migrational behaviors and have those birds ALSO follow the wind, same as your airships (idk if they already do, some birds, I assume more often no). Also, make sure these people are okay with eating flying bugs, cause thats the most reliable source of food I can think of up there. Hope this helps [Answer] They can follow/search for migrating birds and use them as food supply. Ducks and geese, for example, are already used by humans as food. They could stock on them when they get the chance, so to build storage for meager times. Together with that, when the winds bring them above the sea, they could throw nets or lines and fish. Last but not least, they could lower down a single hunter with an harpoon like weapon attached to a rope, who could use it to hunt large game or fish, and then recover it by pulling the rope. This would work on open sea or prairie-like environments. [Answer] ## Trade And they could live as Kings. Trade was important in the Middle ages (specially in the second half). But it was hard, slow, and dangerous. Roads were poor, mountains, rivers, marshes, etc, were huge obstacles, make trade hard and dangerous. The Middle ages lacked good infrastructure. Being able to move through air means many natural obstacles aren't obstacles any more (although crossing seas may still be dangerous, and crossing oceans is probably out of the question). Merchants would pay a premium to be able to trade more quickly. (Not to mention an airship could avoid crossing through towns and cities which levied tolls, and they be harder to rob). ## Warfare An alternative way to live like Kings. They could act as mercenaries. A siege of a town or castle will have a very different outcome if the town or castle could be bombed from the sky. Even if airships would only be used for reconnaissance, the side which has access to airships has a major benefit. [Answer] ## Nomads Can Not Survive This Way The biggest problem with this scenario is that the nomads have no control over where they go. They could have a perfectly good method for feeding themselves in their preferred biome, but then get blown into a desert or mountain range or tundra and then all starve to death because their method of feeding themselves become undoable in the new biome. Remember, the whole point of being a nomad is that you get to choose where to go to find more resources when you need them. This makes your nomads better off just footing it wherever they want to go than being dragged randomly where they may or may not want to be. On top of this, airships are a huge investment in terms of both upfront cost, and maintenance; so, you need to justify that cost with some added benefit. While a family could perhaps survive on an airship, you can not expect hydrogen containment to be perfect. They would have to frequently stop, collect tons of fuel and appropriate minerals to melt rocks in large, and specially designed kilns that can capture the escaping gasses, then run compressors that are frankly WAY past medieval technology to separate the hydrogen from other gases. They would also need to maintain the compressors which is a whole other technological hurdle. This is not even including what other resources you may need like a regular supply of proper lubricant's, waxes, patching material, and what ever else you may need. In short, airships NEED a sedentary port of operations to provide for all of its many needs which a nomadic life style can not provide. Not only would these things make it easy to be taken away from your preferred environment for food, but they would also take you away from your preferred environment for producing hydrogen gas as well! ## How to Improve the idea For starters, switch from hydrogen to hot air. While a hot air balloon may seem like more maintenance because you are always burning fuel to keep it in the air, you can afford to be much less selective in your fuel source. Your nomads could burn pretty much what ever they find be it wood, grass, coal, etc. to keep them aloft. This also removes the need for industrial era machining, to be able to make and maintain your compressors. Second, they need some way to control where they are going. This means you need some manner of propulsion. Since you are already burning wood to keep your airship aloft, it does not take a lot of ingenuity to find some way to convert some of the updraft from the flame into propulsion using a simple windmill/propeller system. You will not get the sort of thrust you may see out of something more advanced like an internal combustion or steam engine, but that is okay since you really need to move fast. So with these two changes, you now have a viable nomadic life style: You can choose where to go, and you can be flexible with what you find when you get there. This just leaves 1 very important detail to address before we can answer your actual question. Why do your nomads invest so much time and effort into building and maintaining expensive hot air balloons instead of going by foot or draft animal? The best answer I can see for this is a very long and inhospitable migration route. Most nomads do not move around randomly, but choose to travel between known spots that are good to be at different times of year. Many nomadic tribes would travel back and forth between places that may be good hunting grounds in one place for winter and good foraging grounds in another place for summer... but what happens when you put a harsh environment like a mountain range between the two? Normally this could be deal breaker because the trip would just end up killing too many people to make, but if each good spot is adequately bad at the wrong time of year, these nomads may have to make the trip anyway. So for many generations, this tribe makes the trip, with people dyeing along the way until someone discovers they can fly using hot air. So, they start making the trip by hot air balloon saving lives and justifying the cost. By going with a mountain range as the dividing feature, you provide a landscape that is dangerous to pass by foot, easy to pass by balloon, and should have enough trees that on a long journey you can set down to gather more wood as needed. So to answer your question, they do not gather food from the air, they transport the food they need while traveling, but they use their airship to go to where the food is at different times of year. [Answer] ## By Landing Unless I'm missing something, what is stopping your airship nomads from landing? Historic nomads followed wild herds or shepherded their own, and gathered wild produce from the land. This means moving mostly with the seasons- not every week, or necessarily every month. This also meant their movements were cyclical. Airships are good for travel, but chock full of logistical challenges for daily living. To be the most nomadic, they could land to hunt food and prepare other supplies weekly at minimum. To be less nomadic (but much more unique), they can cycle between multiple established, resource-rich settlements which other peoples can't reach because of distance and geography. The numerous permanent implements for daily medieval life - looms, mills, wells, forges, wood shops, storehouses - all stay on the surface, patiently waiting for the next time their owners visit [Answer] It depends how easily they can change elevation/land, and at what cost. Without effective propulsion they can still change direction by picking up different air streams moving in different directions at different levels, or land and take off for trading etc... but to do that they need to be able to change elevation cheaply and easily. That basically means either doing so without valving lift gas or their lift gas being so cheap, and widely available, that they don't care how much they use. Neither of those is easily justifiable with technology available in the historical period you've elected to work from. If they can't change elevation/land cheaply for trade and hunting etc... then you're going to have to look at enriching the airborne biome to the point where it can sustain hunter-gather type activity by small groups who are permanently aloft. The sky would have to have a similar travel rate calorie density to that of a neolithic forest, that is there would have to be roughly the same amount of available food calories per hour of travel along the steerable routes as what used to be obtainable in the old-growth European forests that my ancestors used to inhabit. Hunting and/or gathering might be aided by available technology but unless they can farm the sky that would only lead to depletion of food resources see what happened to whales, herring, tuna, wolves, beavers, anything else we nearly hunted to extinction. [Answer] Lots of good advice pointing out the big flaw where do they get the gas? So, to make this interesting, I'm going to give your world one big difference - it already has floating sky animals. (Am possibly inspired a bit by the Gossamers in [Wen Spencer's Elfworld](http://www.wenspencer.com/elfhome-series/)). These sky cows have different intestinal flora that generate hydrogen and there's an equivalent of krill that floats. There may also be lower gravity that makes this all a bit easier. This reduces the navigation issue - there are bands of sky krill in the prevailing winds, so it becomes a closer maritime analogy than you may have started with. A semi-agrarian but more hunter/gatherer society can drift in these winds. The Wooden hulls could be light timbers such as bamboo which gives interesting scarcity issues - finding a good timber crop on a mountain. ]
[Question] [ I'm building a map for a tabletop RPG (Pathfinder specifically), the aim of which is that my players will be trekking around and visiting interesting places. As part of that, I'd love to portray a bunch of exotic climates, such as deserts, jungles and tundra (to name a few). However, on Earth, the Tropic of Cancer and the Arctic Circle are almost 3,000 miles apart, which is a long way to force my characters to walk. Thus my question, what rules do I need to follow, be it manipulating elevation, weather patterns, placement of oceans/mountains, etc, in order to bring my hot and cold climates as close together as possible? As this is a fantasy world, some Suspension of Disbelief or magic can be used, but I want to avoid any jarring revelations as much as possible. [Answer] # Mountains In Peru (for example) [Cusco](https://en.wikipedia.org/wiki/Cusco#Geography_and_climate) is at 3400 meters elevation. The average year-round temps is 12 C, the average low is close to freezing, and it has historically been below freezing every month of the year. Frost and hail are common in all months (although snow accumulation is rare) [![enter image description here](https://i.stack.imgur.com/6xCz1.jpg)](https://i.stack.imgur.com/6xCz1.jpg) Meanwhile only 90 km away, is [Pillcopata](https://en.climate-data.org/south-america/peru/cusco/pillcopata-765096/), Peru, at 500 meters, in the heart of the Amazon. Average year-round temps are 24 C; there is a mini-'winter' in May-July, but the other months have an average high of 30 C. It rains year-round, monsoonally in the summer, about 3000 mm per year, which is three times what New York City would see. It looks like this: [![enter image description here](https://i.stack.imgur.com/scxHh.jpg)](https://i.stack.imgur.com/scxHh.jpg) Changing climate with elevation is called "[altitudinal zonation](https://en.wikipedia.org/wiki/Altitudinal_zonation)." There are plenty of other examples around the world. Elevation will solve all your heat vs cold problems. Snowy mountain highlands can be just a day or two's travel away from steamy jungles. Other examples that I could have added would put cool temperate forests in the mountains above hot deserts (as in Central Asia or the southern Great Basin) or misty forested hills above sweltering fertile plains (like Sichuan province in China, or the upper Ganges Basin in India). [Answer] Geothermal springs can create a warm, lush forested region in the valley of a frozen mountain range, just as natural springs can create a large oasis in a desert. I suppose it would be possible for strong ocean currents to reliably carry large icebergs from a polar region to the beaches of a tropical region, and thus support cold-weather flora and fauna in the waters and on land year-round. [Answer] In the foothills of [Himalayan Mountains](https://en.wikipedia.org/wiki/Himalayas), winter temperatures regularly go below freezing. The upper reaches of the mountain range are covered in ice year-round. But, if you travel a few hundred kilometers south, you reach the Tropic of Cancer. Some of the Indian states in this region have temperatures approaching ~50°C at the peak of summer. There is hardly any winter in most South Indian states. A few hundred kilometers west from central India, you have the [Thar Desert](https://en.wikipedia.org/wiki/Thar_Desert), with all geological phenomena you can expect from a desert. A few hundred kilometers east from central India, you reach the towns of [Mawsynram](https://en.wikipedia.org/wiki/Mawsynram) and [Cherrapunji](https://en.wikipedia.org/wiki/Cherrapunji), two of the wettest places on earth by annual rainfall. The South Indian peninsula is surrounded on three sides by the Bay of Bengal, Arabian sea and the Indian Ocean. This means that there are long stretches of coastal areas on both sides of the peninsula with moderate climate year-round. During Monsoon season, the eastern coast faces [Cyclones](https://en.wikipedia.org/wiki/Tropical_cyclone) (Hurricanes) every year. And in the tropical states the Monsoon season lasts for more than two months when it rains almost continuously everyday. From Wikipedia article [Climate of India](https://en.wikipedia.org/wiki/Climate_of_India): > > The Climate of India comprises a wide range of weather conditions across a vast geographic scale and varied topography, making generalisations difficult. Based on the Köppen system, India hosts six major climatic subtypes, ranging from arid desert in the west, alpine tundra and glaciers in the north, and humid tropical regions supporting rainforests in the southwest and the island territories. Many regions have starkly different microclimates. > > > TL;DR - Send your trekkers to the Indian subcontinent. [Answer] > > on Earth, the Tropic of Cancer and the Arctic Circle are almost 3,000 miles apart. > > > If you drop the jungle from the requirement, you only need to walk 1/3 of that. ![Los Angeles to Olympia](https://i.stack.imgur.com/aEZcZ.jpg) You could wander from the Mojave desert in California all the way north to the temperate rain forrest from Washington. A little further north and you get tundra in British Columbia, I think. If you still want that jungle you can handwave it with [magic](/questions/tagged/magic "show questions tagged 'magic'"). Terraria and other videogames have underground jungles and nobody complains about that... Kinda adds to the whole magical and fantastic theme. [Answer] ## Bring the glaciers closer to the equator Since you're not confined to Earth or Earth-like geological parameters, you can do whatever you want. Ways to achieve close geographical proximity of wildly varying climate zones * Bring the glaciers closer to the equator. While climate and ice sheets are linked, since we are designing a planet to do what we want. Just plunk down some ice sheets over the large land masses. This will increase the steepness of the thermocline from its maximum at the equator to arctic wastelands. * Reduce the amount of atmospheric greenhouse gases. This feeds into the mass glaciation but also decreases the amount of heat that the atmosphere can hold. Effects of these Changes Since the glaciers come so far south/north, they push the tundra ahead of them. This overall compresses the distance required to go from tropical temperatures to arctic conditions. At the equator, start with lush jungles. Temperatures are high because of the strong solar heating. Further north where solar illumination is weaker, temperatures start to cool. Temperate forests and cooler rain forests would appear in this zone. Still further north would be desert conditions where the descending air from the tropical Hadley Cell descends carrying relatively moisture free air. Beyond the warm dry zone, temperatures will continue to fall to tundra then arctic conditions. [Answer] Have strange ocean & wind flows. Possible causes for strange ocean flows : * Extreme version of deep sea "volcanos"/smokers : [![enter image description here](https://i.stack.imgur.com/NuZZj.jpg)](https://i.stack.imgur.com/NuZZj.jpg) Possible causes for strange wind flows & climate : * Astronomical configuration : have multiple suns, or multiple other planets leading to a complex lighting of your planet; some parts would receive more sunlight, thus be hotter, and others would be in the shadows. Your planet could also be small(or even a moon) and spin around strangely. * As already mentioned : Height differences + Expanding on this point : Mountain Ranges - Imagine a valley surrounded by high mountains. The climate in it can be totally different from the outside; for instance, rain clouds would be raining over the mountains and "filling" the valley ]
[Question] [ I recently watched the classic film [Gattaca](https://en.wikipedia.org/wiki/Gattaca), which is about a world in which humans are selected with desirable traits at birth. Ignore all the ethics of abortion and genocide (like those claimed for Iceland). I can not help but notice that human biological variation will take a big toll and the presence of mutations in the population would become virtually non-existent because they almost always are initially a disadvantage (until adverse environments are formed). Any species will be able to survive for maybe a century or so, but with the course of time there will inevitably be an event in which the current "desirable" traits would not thrive. In fact, this could lead the race to extinction because common mutations that could enable the species to survive may be lost. These technologies are present in the world right now, and technology to design new genes was neither shown in the movie nor is present in the current world. Superior children are chosen based on the genes of the parents only (in the real world, we also use genes from other sources). Whether or not it is indeed possible to design new genes is out of scope of worldbuilding I think, so I have left that out as a grey area. My first question is whether I am over-exaggerating the issue? Second, if not, what can the society do to manage the growing trend to survive in such a potential future? [Answer] Yes, species can survive eugenics. Many already have (though admittedly not sapient species). Every single species ever domesticated by humans such as cows, dogs, cats, bees, pigs, chickens, llamas, horses, sheep and innumerate plant species have undergone 'eugenics'. Humans have selectively bred these species for millennia, and they have not died out yet. It is true that negative health impacts have been seen in some of these species. For instance, the banana is now incredibly vulnerable to pathogens, the pug can't breathe properly, and the chicken has a lot of problems pumping out so many eggs. These creatures have not been driven to extinction, mainly due to the fact that the decrease they experience in biodiversity is made up for by the increase in numbers from being artificiality spread across the world (something that is not a problem for sapient species that are extremely effective at proliferating across the worlds they inhabit). Is it possible for eugenics to cause irreparable damage to a species genetics? Yes, but only if done ineptly. For example, I point you to sixteenth century European monarchs whose obsession with intermarrying and royal purity caused major inbreeding and ultimately led to the downfall of many royal lines. That being said a semi-competent but nonetheless evil state wouldn't need to worry. Worst case scenario you just slightly irradiate sperm before use to introduce additional mutations into the gene-pool. That being said, just because something probably won't wipe out humanity doesn't mean it should be done. [Answer] You are seeing diversity as a safety net; when the whatever comes that kills 99% for sure we won't be certain what made that 1% special ahead of time or we would have seen to it it wasn't only 1%. But if a great purge never comes it isn't certainly important. Eugenics looks at genetics like wealth; if we have stockpiled enough advantages when Bad Things happen we will get through it using those advantages. Or like maintaining any other code; finding and removing bugs during good times means bad times are both rarer and less painful. A eugenics plan thought out well enough to be repeated sober isn't likely to kill a species by itself. Even breeding for hemophilia or cancer vulnerability wouldn't certainly be doom. Because to get to the point of considering eugenics you have to have brain power and strong social cohesion. Intelligence and social cohesion are very powerful traits that can conceivably cover any biological limitations; a million years ago who would have bet on the apes? The story goes that some of the oldest writing in the world is complaints about people being less tough than they used to be, but quality and quantity of life pretty consistently improves on average by any standard. Modern medicine especially antibiotics, hygiene and vaccinations do not contribute to our genetic fitness, but vastly reduce the threat of Bad Things. Further homogenization isn't a certain outcome for eugenics. It takes many generations to achieve any breeding results, humans have pretty long generations and there are many different conceivable goals so it could make sense to run multiple lines in parallel. Certainly if it is considered on a species level you have the population to do so. [Answer] I'm not a professional geneticist, but what I do know about the topic is that every change isn't a net gain or loss; it's a tradeoff. Some of us (for example) metabolise excess energy intake from food into fat. This is a great trait for areas where food is scarce and lets us build up reserves when larger food supplies are available. Where it falls down is in areas or times of plenty, where the increased fat reserves actually hinder survival should the Bad Things happen. Some of us metabolise excess energy as heat; great for cold environments, not so great in the tropics. Yet others metabolise it as muscle. Quite rare, but it allows for increased strength for (say) areas where the principal food source is predation. The point being; what we consider to be 'good' or 'bad' largely depends on our environment at the time, and it's that change in environment which essentially is the Bad Thing that causes us so many problems. One of the things that has made humans so successful has been our generalisation; we can eat a much wider range of food than most animals, can use our limbs to do a wider range of things than most animals, and where the environment is still hostile to us, we have learned to adapt the environment and ourselves to suit. Think fire, clothes, agriculture, etc. It's that ability to adapt and work from a generalist base that affords us the most protection from the Bad Things in our future and as a general rule, eugenics is often described as a form of specialisation. It'll make us smarter, stronger, etc. Only thing is, there is no such thing as 'stronger', there is only a tradeoff between fast twitch, total muscle strength, stamina, etc. In other words, you can be more agile, have more endurance, but not both (beyond some basic general improvements). Same goes with strength and flexibility; you can't be specialised in both. You can burn off excess food as heat, OR you can store it as fat. You can't do both. The first means that you can eat (almost) as much as you want and not gain weight. The second means that you can eat far less and still be comfortable. Which is the better trait for survival? But, which is the one everyone wants? Ultimately, eugenics can tune the human body to be better overall only to a point; after which, specialisation is the only way to improve specific traits, and that always comes with a cost. Eugenics may not destroy a populace, but ultimately it may make it harder for people to survive with specialisations that the Bad Thing makes undesireable for some reason. [Answer] I agree with the top answer that dogs are a perfect example of long term eugenically selective breeding, without them dying out (though you could argue that the average small dog is less equipped to survive in the wild now). However, it seems you're conflating a few things. > > mutations in the population would become virtually non-existent > > > Mutations are an exception to genetics. In most cases, picking a certain set of genes from either parent will give you a guaranteed outcome. Dominant and recessive genes are a basic example here. Mutations, however, change the expeted outcome. They are unforeseen and happen randomly. Mutations will occur regardless of whether you handpicked the genes (eugenics) or shufffled them randomly (biological reproduction). The only way to prevent mutations from occurring would be to alter the biology of actual "baby generation" (I can't find a better name for it). Most eugenics I've heard of (including fictional) generally revolves around picking the desired genes but still letting nature take care of the actual "baby generation" process. > > because they almost always are initially a disadvantage (until adverse environments are formed) > > > Adverse environments are not formed because of existing mutations. Mutations do not occur because of adverse environments. These two things are separate and coincidental. A mutation which coincidentally happens to solve a problem, will enable the mutated animal to have a better chance at surviving an adverse environment, thus allowing the animal to reproduce more and generally spread its mutated genes around. --- Disclaimer: My answer focuses on practicality, not ethics. I'm not personally advocating eugenics. > > My first question is whether I am over-exaggerating the issue? > > > Referring back to what I said before; I think so. Mutations will still occur. There are three possible outcomes: * Positive mutations have a habit of sticking around. This applies to nature (more reproduction, either through increased survivability or mate selection) and eugenics (more people choosing the mutated gene) * Neutral mutations will generally mean that there's no discernible drawback or benefit, which means it slips by unnoticed (e.g. the color of your stomach lining - no one cares). The odds of the mutation persisting is effectively random chance. * Negative mutations have a habit of being weeded out. This applies to nature (less reproduction, either through decreased survivability or mate selection) and eugenics (choosing to avoid the mutated gene). Putting ethical issues aside, eugenics are really just speeding up natural selection. Arguably, being free to choose your mate is selective eugenics. Which means that pretty much every animal engages in eugenics. By selecting the right mate, they are somehow able to maximize the (still somewhat randomized) genetic outcome of their offspring. Natural selection is a slow, brute-forced process, but it usually ends up consistently improving a species. Eugenic selection can be incredibly fast and can bypass the brute-forcing stage because intelligent decisions can be made. However, this does open the door to making intellectual mistakes that negatively impact a species. Two examples of this, one fictional and one real: * Jurassic World. An dinosaur is eugenically bred to be the most amazing killer, to amaze visitors. And then it outwits the zoo keepers and escapes. * Killer bees. Created during research. Not intended to be let out of the lab. Then they escaped. > > Second, if not, what can the society do to manage the growing trend to survive in such a potential future? > > > I'm not sure what you're asking here. Regardless of whether a baby's genes are hand-picked (artificial) or randomly shuffled (biological), the baby counts as one life. Are you assuming that eugenics will increase the amount of babies that everyone has? That eugenics will nefariously implement a "planned obsolescence" in cheap eugenic options? These are interesting things to explore, but your question as asked doesn't really explore this. What do you mean by `the growing trend to survive in such a potential future`? If anything, you'd expect gene choices (for eugenics) to be made specifically to improve on the otherwise randomized gene selection. If eugenically created babies were somehow more defective than their biological counterparts, there'd be no reason to chose eugenics over the natural way. [Answer] > > My first question is whether I am over-exaggerating the issue? > > > # Yes First, unless there was widespread genocide, different societies and different families are going to have different opinions on optimal genetics. No one wants Down syndrome &c. or poor cholesterol handling &c. but (a) those mistakes don't make up the majority of the genetic code and (b) it boggles the mind to think of any change to our natural environment that would make them adaptive. If your society is expecting parents to have any bond or connection that prompts them to love and raise children (rather than handling them all through central caretaking, which current human development wouldn't handle well at all), then it's going to have to leave most of mom and dad's DNA and simply remove problems; it won't be able to give people clones of the ruling class and expect them to be at all cared for. Second, mutations occur as a natural part of cellular reproduction. We'd presumably keep track of the code at birth, but living beneath the sun produces its own edits, as do a host of other human behaviors. If anything, being able to restore genetic code (i.e., cure cancer) would permit people to indulge in more risky behavior than at present. Third, if a massive environmental change (e.g. nuclear winter) occurred that made most humans' genetic code maladaptive (e.g. too little vitamin D and too poor endurance in low-temperature environments), the level of tech that you're describing would presumably allow CRISPR and other tech to 'patch' not only fetuses but many or most of the existing population. > > Second, if not, what can the society do to manage the growing trend to survive in such a potential future? > > > The only maladaptive changes are likely to be * Cosmetic. With complete control of the genetic code you'll have many people—in East and South Asia if not Europe and the Americas—wanting lighter skin that provides less protection against solar radiation. It's not really an issue since there's sunblock and, as mentioned, the potential ability to 'reset' cancer produced by this vector. * Gendered. Some traditional societies prefer male children to female, which can skew the population in unpleasant ways. It usually works itself out—societies advanced enough to deploy this tech en masse typically value women—but places where it doesn't may require government intervention. That happens, as do societal changes like Chinese weddings now being paid by grooms, who are expected to provide gifts, a house, and a car, which makes having girls more advantageous for a family. * Metabolic. On a personal level, it may seem fun to eat without gaining weight while increasing everyone's height and lean muscle mass. On a societal level, it's obviously problematic if everyone's caloric intake bumped up by a factor of two or even to Ryan Phelps levels. Even with present-day tech, though, that's not insoluble. It just means we'd need to spend a lot more of our income on food, esp. proteins, until lab-made meat caught on. Esoteric foodyism would have to go by the wayside except for the overclasses. So, unpleasant tradeoffs, but survivable and probably worth it. The only real epidemic risk of genetic modification is new tailor-made diseases; their threat would be real, since they could target some of the universally employed adaptive changes, but they'd be just as simple to fix via CRISPR &c. once scientists could identify the genes or proteins being targeted. It'd just be much more essential to avoid total wars or permit access to the offensive/defensive part of the tech by private individuals, similar to how nuclear power is treated now. [Answer] There are in general three condition that can make a species die out. 1. Competition. A more fit species crowds them out. 2. Their only food source dies out. 3. A new predator or disease arrives from somewhere else. They/It cannot be a locally evolved since the prey would then have evolved right along with it. In some cases local diseases can push a species over the edge, but only if they are already threatened by one of the big three. Otherwise there will always be some survivors that can bounce back and repopulate. Now look at humanity: 1. Humanity has no competition. Not even close. 2. We make our own food. We eat many different foods. If another Potato Plague arrives, we might run low on food, but we will never run out. 3. There is no "somewhere else" anymore. Unless you add aliens. So, mankind is basically in a very good shape to handle crises of almost any sort. We are also pretty smart, which gives us a huge toolbox to handle otherwise serious problems. Medical science is utterly amazing already and will only get better in the future. Gattaca style genetic selection will narrow our gene pool. This will make us more susceptible to diseases and parasites. BUT: Our other advantages means we can shrug off the consequences. Or so I believe. One problem I see with Gattaca as a future is that they are selecting against mental illness, which probably means they are also selecting against creativity. Expect stagnation. [Answer] On Earth, from the perspective of climate change, if eugenics resulted in a net reduction of the population, then it could actually improve our long term survival. I say this on the basis that if eugenics significantly narrows the range of people who were permitted to breed, that might diminish the size of our population, which would then diminish deforestation and consumption of fossil fuels, which would slow down the speed that animal species go extinct, which could lead to the food web staying intact instead of collapsing. I should point out that, on a related note, the human species is one of the species most resilient to extinction on the entire planet. The only real threat to our survival is to destroy our habitat and the food web. For instance, it's been claimed that if bees went extinct, the human species would go extinct as well within four years (because pollination is vital to our food supply, breathable air, mitigating the greenhouse effect, mitigation of soil erosion, and the way in which plants provided food supply for all other animals). We could very well be one of the last macroscopic species that is still standing, but if everything below us goes, so too will we go. If other animal species can be preserved, we will be preserved. I know this sounds unrelated, but loss of a livable habitat is one of the only near-term extinction threats that our extraordinarily adaptable species can't overcome. Our population has been continuously burgeoning, and disease has failed to slow it down. In fact, the global population is currently about 16.5 times as high as it was just before the black plague. The original question assumes that conventional evolutionary pressures could wipe us out, and they could, but on the whole, we are much more resilient than that. But anyways, off the tangent and back to the main discussion. Provided that eugenics is informed by health science and not racism or vanity; we should be selecting to weed out genetic diseases, weak immune systems, autoimmune disorders, etc. If that were the case, we would already have a substantially improved mortality rate and greater survival in the face of a potential extinction event (presumably a pandemic plague). Remember: some diseases like influenza have higher kill rates among the already unhealthy and immune compromised; so as you select for stronger immune systems, less autoimmune disease, less asthma, etc., you have fewer people dying from these potential contagions. But as you see with the Cavendish banana, all members of this cultivar are essentially clones, and thus they are very vulnerable to global extinction (which the previously popular Gros Michel cultivar already experienced). Any sort of eugenics program should ensure a degree of genetic diversity and immune system diversity. Instead of totally removing a lot of the population from the breeding pool, you should be screening their individual reproductive cells for cells which don't contain deleterious traits, and allowing conception with their healthy reproductive cells, if possible. ]
[Question] [ PREMISE The zone will make all electrons disappear. QUESTIONS If a person walks in that zone with his whole body, would he die from heart failure? What happens if he just sticks his hand in? Hand become numb? What happens if he sticks his head in? Brain dead? --- Addendum What would happen if the electrons disappear at a fast rate (not instantaneous)? If electrons from the surroundings (outside of the zone) start to fill in and create a flow, would the person get electrocuted? [Answer] They would die by violent "nuclear" explosion - that is, explosion into individual nuclei. Electrons are what hold molecules together. If they were to disappear, there would be nothing to prevent the positive charges in the nuclei of the atoms in the person's body from repelling each other and flying off in all directions. [Answer] If it is at a certain rate, and not instantaneous, what you basically have is [Oxidation](http://en.wikipedia.org/wiki/Redox). A very good oxidising agent strips electrons from nearby atoms, and takes it for itself. For example fluorine gas, when exposed to water will "burn" the water due to the oxidation of Oxygen. Basically, there is a lot of energy stored due to the attraction between the nuclei and the electrons. Stripping them away, releases that energy, sometimes very explosively. So the "constant rate" part does not really change that much from AdamHovorka 's answer. [Answer] You need electrons to turn atoms into molecules. No electrons = no molecules = you're gone. You'll have fully ionized nucleii floating around--in other words a plasma. Nothing but plasma can exist in such a zone. As others have said, the effect will be quite violent but you would have ceased to exist before the violence did anything to you. [Answer] In this scenario I handwave the initial explosion. Other answers have covered that, and I find the story would not be as interesting if you turn on the field and the Earth explodes, killing everyone. The end. Here is what happens without the explosion: There will be huge amounts of lightning as nearby electrons shoot into the field. This will create an area of glowing hot plasma surrounding the field. You can forget about even getting into the field, the lightning will give you a fatal shock to your heart before you can even get to it. That is, if you somehow survive the intense heat and the thunderclap. After checking whether plasma is conductive, I realized that the lightning will keep expanding. The electrons will have an easy path through the plasma to the field, so the storm will engulf the entire planet and steal all of the electrons. Then, I am tempted to guess that the effect will stretch to the solar wind, and there will suddenly be lightning shooting from the Sun to the Earth like giant Tesla Coils. However that part is purely speculative, I don't know if it would extend to the Sun, the solar wind might not be dense enough. [Answer] The lack of electrons would prevent vital chemical reactions from occurring, thus, the body ceases to work properly ]
[Question] [ Closed. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Add details and clarify the problem by [editing this post](/posts/183751/edit). Closed 3 years ago. [Improve this question](/posts/183751/edit) I’ve heard a few people imagine an alternate history where people are completely free to live in whatever country they choose to. Countries/city states would have to maintain a high standard of living in order to keep people from moving away, creating an almost free market where nations compete to keep their citizens happy. I’ve always sort of grouped this with sentiments like “instead of war we should play chess” which sounds amazing and would be great it just wouldn’t work very well in the real world. But recently with everything going on I’ve started to wonder if this could work. So specifically, can anyone imagine a plausible scenario in which instead of nation states with defined borders and immigration policy, the world is instead made up of spheres of influence of various governments that allow people to move freely in and out of them. [Answer] Nomads. [![sioux](https://i.stack.imgur.com/J4pWT.jpg)](https://i.stack.imgur.com/J4pWT.jpg) <https://en.wikipedia.org/wiki/Sioux> Nomadic people range over large territories. Within a territory one would likely have an idea of what peoples one might encounter there. The inhabitants might attack you, or welcome you, or ignore you but not because of the particular piece of ground where you met; it is just because you met. If people decide to range more widely there is nothing stopping them. You can go where you want to go. If you decline to go into a place occupied by a given people, it is because you are avoiding those people, not because of rules they are enforcing about arbitrary boundaries. [Answer] Such a world has been the norm until roughly WW1 That was the time when mass transportation became cheap enough to even allow migration to be of sufficiently large enough numbers that getting more immigrants became a recurring problem. (Singular large-scale immigration incidents were handled on a case-by-case basis, sometimes repelled, even by military means, sometimes invited such as when Huguenots fled France and were welcomed by the King of Prussia.) Borders did exist, but in the middle ages, they were more important for defining who can draw his income from what area of land; state bordes were only relevant to the kings, much less to their barons, and totally irrelevant for peasants. Law didn't regulate day-to-day issues, that was left to the local population, who defined their law. So emigrating to a different countrly was just as easy or just as hard as relocating to another village! As travel became faster and cheaper, immigration became more common, so issues around immigration (such as immigrants not knowing or not caring about local law) became more commonplace, so immigration laws sprung up, and border controls became more important to be able to enact those laws. Another reasons for immigration control were epidemics. If you know that Genua has an outbreak of The Plague, you want to know where your immigrants are coming from, so you can turn any Genuese away. This didn't help much, but the ability to tell where somebody came from was useful in other ways, so whenever a stricter identification scheme was introduced, it stuck, and the world gradually moved from travel permits to passports to border controls to security checks. Since this checking was annoying and time-consuming, actors tend to cut that down; the world has been trying to find a new balance for this, and different areas have been experimenting with different policies, according to administrative capability and need. So, for worldbuilding, you need to know what your states' needs and capabilities are, and organize them so they either cannot or don't want to enforce border controls. A world where states are powerless to enforce immigration would be one answer - this could be either medieval (lack of capability to control), or very modern (legal restrictions over controlling immigration). The other answer would be a world where states are disinterested. People would have to be powerless to do anything relevant (a machine world where humans do not matter much at all and are a nuisance at best), or a post-scarcity post-epidemic world (Iain Banks as written a lot in such a setting). Humans would have to be unable to access weapons of mass destruction, such as explosives or bioweapons, to make that work - otherwise you need to control humans for their motives, which usually translates to controlling their origin. [Answer] *When people aren't important to governments:* In a post-scarcity future where people are citizens (or not), then those people are not a significant issue for governments to deal with. Property is owned by governments, or perhaps AI's who actually DO all the work. Taking care of citizens is a relatively trivial issue, so the government feeds anyone who asks for food, arrests anyone who breaks a law, and provides free housing for anyone who wants it, wherever they happen to be. The important things to governments, like mines, power stations, citizenship of AI's, and manufacturing facilities, are all unaffected by the petty needs of mere humans. Doubtlessly, some governmental AI is tracking everyone in the world constantly, but that is easy. The government simply DOESN'T CARE if citizens leave. They don't NEED people any more. Anywhere they go, the same rules apply. When people aren't needed for labor,they aren't a threat and aren't an asset. At the same time, the people have no say in how things are run, because even if there was voting, there are 200 trillion AI personas with voting rights, so human input is irrelevant. Humans can't sabotage anything, as machines are watchful and smarter than we are. Humans can't betray their state, as nothing they could do is a real threat. So if you want governments to have no restrictions on what people do or where they go, simply make people unimportant to the state. Humans are a side issue, a distraction from the new upgrade to national computing systems and the exploratory mission to Alpha Draconis. [Answer] Today, overpopulation is a problem. We procreate faster than we are able to generate jobs. That's the main issue: immigration is seen as a threat to wealth because of additional hungry mouths to feed. This is not true. Economists around the world [show regularly](https://www.amazon.de/Good-Economics-Hard-Times-Problems/dp/0241306892) that immigrants increase wealth and boost economics wherever they go. That's because they have an adventurous mindset which let's them take more risks when founding a company. They are also more likely to take jobs the natives don't want if they don't make their own enterprise. However, what I said first is what the people feel. And that is why so many governments close their borders, it's pressure from within. Now take the US as example. They are a bond of many states with different laws, sometimes different cultures and totally free movement. Also, there are really vast differences in richness. And do all the poor people from the central land storm the islands of richness? No they don't, as long as they can reasonably stay where they are, close to their friends and relatives. They even accept poverty if they just can stay where they were born. So if a policy would be set up worldwide, which allows to manage countries in a way so that they all become safe places to stay in, migration will become a non-issue. Then you can as well open the borders. Today it's a sad fact that there are countries where you starve or get bombed if you stay. Yes of course, this is where people leave. Because they have no choice. [Answer] # Sure, if one group conquers the world and oppresses or kills everyone who disagrees with them. Simply put, one of the reasons why there is friction between groups is because different groups of people have different desires and values as a part of their culture. The only way to stop this is to get rid of local cultures by creating a single, hegemonic global culture that everyone is a member of. The simplest way for this to occur is through military conquest and genocide. More subtle methods involve the sorts of slow cultural assimilation and obliteration championed by modern-day "globalists" that seeks to impose a certain type of international Western culture on the entire world through propaganda and consumer products. [Answer] Your entire life has been as a fish in an ocean, so you don't know a word for "wet" or "dry". The modern nation state is, well, modern. It is a recent innovation. A blink of an eye ago, personal loyalty to a crown was the closest thing you had to it. Immigration restrictions where even more recent than that in most of the world. People where relatively free to move into your area; if they where unable to support themselves and proved a nuisance, the locals could just kick them out or kill them (I'd say "the local police", but police are also a recent invention). Much of what you presume is inevitable is just an accident of history, where some area comes up with a social pattern that other areas duplicate. Right now, there are four large empires -- India, Europe, China and the USA -- which are each as large economically and population-wise as the world was not that long ago, and a number of smaller (economically or population wise) polities. Within them, to a greater or lesser extent, you have free movement of people. With modern transportation technology, completely free movement of people would lead to significant migration. Typically, migration grows when wealth per person becomes a large multiple, and in our world there are areas that are 100x poorer than others. In the last 20 years we have begun to eliminate absolute poverty. There are now fewer absolutely poor (using many measures; Y2K 1$ USD@PPP a day is an example of one) in the world right now than we have lifted out of poverty in the last 20 years. Assuming the various crisis (fall of the Western British Empire, climate change, MAD, etc) going on don't derail the efforts, it is plausible that absolute poverty becomes a small problem within decades, and the global middle class swells to the point that huge chunks of the world can open up free migration without overwealming immigration flows occurring. It becomes plausible that 60%+ of the world becomes a free-movement zone. The remaining parts will probably form imitation free-movement zones of smaller size, as politicians are nothing if not copy cats. TL;DR much of the world is already there, just the bubbles are not connected. Having a free movement North America is quite plausible, then linking North America to Europe, and from there to the entire former USSR and East Asian democracies would be doable even without a significant economic upheaval (and would be an example of how the Western British Empire could delay its fall). The resulting political block would have the highest population, military might, and economic strength on the planet. (1.7+ billion people, 50+ trillion GDP 50+ million km^2 area) (This is over 1/5 of the world's population, 1/3 of the world's land area, and 1/2 of the world's GDP). Then other pieces of the world would seek to mimic it. [Answer] Freedom of Immigration vs. Freedom of Emigration To leave your country is an internationally recognized human right. To enter another country requires the permission of that country. This permission is granted when it benefits the receiving country, and it is also supposed to be granted at the first safe stop when a refugee flees from persecution. That leaves the right to emigrate a hollow promise when it comes to people from underdeveloped countries surrounded by other underdeveloped countries, or people from economically underdeveloped countries without gross persecution. So you would have to create a situation where many/most countries actively want to recruit citizens. * Create a setting where even unskilled, elderly and infirm workers are a benefit to the economy. That sounds medieval, with lots of manual drudge work and no need to pay pensions or healthcare for the elderly. Would the right to emigrate survive under those conditions? * Create a setting where a high population, by whatever means, benefits the country. Say there is a global regime of [emission credits](https://en.wikipedia.org/wiki/Emissions_trading) keyed to population. This emissions trading is backed by a stronger UN which also protects human rights like the right to emigrate. * Create a strong legal tradition where computer programs cannot enter contracts, but people can enter contracts through computer communications. That creates a labour market for "signers" -- people who sign, in the name of the internet company, whenever the computer tells them to sign. This creates a "man in the loop" without any decisionmaking, just to cross all t's and dot all i's. But all those situations mean break down if the country spends more on the citizen than it gains from the citizen. And that almost precludes your idea of high-standard-of-living countries which let anyone in. Compare the [EU Blue Card](https://en.wikipedia.org/wiki/Blue_Card_(European_Union)), which is keyed to a binding job offer at 1.5 times the average salary. Most people who can earn a salary in the $500,000-range already could immigrate into most countries in the world. It is the people without a job, or with a low-paying job, who get stopped by visa requirements. [Answer] If there is a reasonably uniform standard of living, economic development, social welfare, education etc. The EU already has a freedom of movement and freedom of residence policy. Which means EU citizens can just travel and live where they want to (within the EU). There have been problems with people from countries with a weaker social welfare system taking advantage of social welfare in richer countries. And recently the whole system has been somewhat suspended because of Corona. But overall ir has worked quite well during the last two or so decades. [Answer] I see four other ways this could happen: * A powerful company taking the majority of the worlds employment. Employees can move anywhere the company tells them to, and governments have to shut up and take it. * Similar to the above; a powerful union forms from all employee unions on the planet. Enforcing border controls against union members could result in a total strike in your country. Once the union gets large enough border controls are no longer practical to enforce, even for non union members. * The planet is originally populated by colonisers who are already united. Eg 50 NASA ships land on Mars and establish colonies simultaneously. * Identity changes due to external growth. Eg establishing an intergalactic empire will blur the distinctions of states and countries together. How can I consider myself (Australian) different to a nearby New Zealander if we both identify as earthlings, and our news feeds concern us about immigration from other solar systems, and wars with neighbouring galaxies? [Answer] No one seems to mention USSR, which controlled half the world. People could move more or less freely in that country. Like my grandparents, who would go to Georgia from Ukraine for vacation (or flee to Kazakhstan as Nazis were conquering Ukraine). Not only that people could move "freely", the vast country had all possible geological resources and could rely on itself without any imports. There are also dark sides of it. People were forcefully moved around the country to "help cultivate the area" aka "go, build big road. if you die, you die, if not, go build another one" or just because they could (Tatars were forcefully removed from Crimea, despite them being there for several hundred years, came to crimea when Ottoman empire was on its height) Also this dark side is the dream of every vulture capitalist, who just want to pay less wages and have "slaves" (This is why there is a big push for all kind of unions, such as European Union, African Union, North American Union and so on) George Orwell's 1984 also had something similar. I've read somewhere, that in the world of 1984 all of governments are actually allied, but throw occasionally bombs on each other to keep people in a state of fear and create a neediness for a government. Wars against Oceania etc. are all propaganda. Also there is a study or something similar, which I came across in my time in University, where it says that if there were no borders, 80-90% or more would all move to the wealthy countries, making the wealthy countries to "shitholes" and their own 3d world countries would become a paradise, because there is almost no one left there and people can live like kings. Unfortunately I can't seem to find the right words to search for in google. Maybe someone knows about it. It was in connection with "brain drain". [Answer] That's clearly the world we're heading towards, given the level of interest in this question. Remember, history is driven by human desires, and the more universal a desire is the more power it has to shape society. The desire to move and settle wherever one wishes is clearly a very powerful and very universal human desire. What stands in the way of this desire? I would argue that there are two main obstacles standing in the way. The most obvious obstacle is of an economic and logistical nature. People do not tend to move and settle to random places on the globe. Rather, they prefer to move and settle to places with a high standard of living and with access to secure and good paying jobs. These places are typically cities, and more specifically, cities in developed countries. However, there is a limit to how many people can actually live in those cities without causing massive overcrowding and without causing the cost of living in those cities to skyrocket. This issue can be mitigated to some extent by building lots of high-rise apartments and/or expanding the city outwards (Melbourne is a good example of this), however, even then most people simply "cannot fit" in any given city. For example even if you somehow increased the "carrying capacity" of Los Angeles to 100 million (an insane amount), you would still exclude 98.7% of the world population from ever living in Los Angeles. What applies to particular cities also applies to entire countries as well, as this example can always be scaled up to larger populations. The second obstacle consists of ethnic, cultural, and linguistic differences between countries. Mass immigration of foreigners into any given country will cause that country's unique ethnic, cultural, and linguistic identity to be weakened if not irrevocably destroyed. Assimilation of the foreigners mitigates this to some extent, however, assimilation is never fully succesfull because the foreigners often can and do look different from the host country's population (visible minorities) and they and their descendants know that their history is not the history of their host country. Therefore, to the extent that the host population wishes to preserve their unique ethnic, cultural, and linguistic identity they will support immigration restrictions. However, if one looks at the younger generations around the world today it quickly becomes obvious that the linguistic and cultural differences between them are smaller than ever before in history. This is because most of these people spend a lot of their time on the internet, and the internet is the greatest cultural and linguistic homogenizer ever created. Since these younger generations all grew up in this same internet-based culture they will increasingly perceive the extant cultural and linguistic differences between their parents as anachronisms. The historical precedent for this consists in the development of modern newspapers and of the telegraph and railway networks in the early 19th century in Europe. These were also great cultural and linguistic homogenizers for their time and did much to erase local variation in culture and language, giving rise to national identities and leading directly to the unification of Germany and Italy (as well as to the breakup of Russia and Austria-Hungary). Insofar as the internet consists of the same phenomenon applied to a global scale a worldwide unification is inevitable, as the younger generations will no longer be invested in their local identities and those identities will perish. With no local identity and with everybody sharing the same internet-based culture any foreigners coming into a country will no longer be foreigners at all. This will remove the second obstacle to immigration completely. The most likely result of all of this is that more and more countries will establish EU-style Schengen zones of free movement, at least between countries of similar GDPs per capita (to prevent a mad rush for the cities from millions of people from poor countries). To give a concrete prediction: I think free movement between the USA and Canada is very likely in the near future, as is free movement between the Commonwealth countries (CANZUK). Political unification will be more tricky, but seems inevitable in the long term going by the examples of Italy and Germany. ]
[Question] [ Background In the Great City the underground sewers extend to all but the most impoverished households. Most dwellings have an outside privy for their needs as indoor toilets are relatively new. The sewers form a vast interconnected network that is inhabited by thousands of rats. The Emperor's Adviser has been tasked with improving communications throughout the City and has come up with the idea of rats carrying written messages in little waterproof capsules around their necks. Sewer rats are captured when young then trained and finally released into the system to carry out their duties. How it works A householder who wants to send a message drops their own trained rat into the privy whereupon it makes its way to the central exchange (Rat Central). There an operative removes the message, feeds the rat as a reward and releases it to run back home. The operative then attaches the message to another rat that is trained to run to the indicated address. Assumptions The society and technology is similar to that of the Roman Empire. Rats are trained only to run between their home and the central exchange (Rat Central). They know they will get rewarded at the end of each run. Rats are provided with little fixed ladders to help them get out of their home privy. Richer homes have special tunnels built for the purpose. Businesses or individuals that have to send many messages have large stables of rats and a staff to look after them. Question Is this system viable? What could go wrong? Notes This is not the same as pigeon post because the rats are trained to run in both directions. Unlike pigeons they aren't taken away from home and then released. Also pigeons can be trapped, shot or attacked by hawks. They can be blown off course. Rats in tunnels aren't subject to these problems. Please assume that rats have been reliably trained to run back and forth between their home and Rat Central and that they don't explore other tunnels or stop for long rests. [Answer] So basically this is a "star" network where the data packets are rats. <https://en.wikipedia.org/wiki/Star_network> The Exchange is where the interesting problems are, and it also is your bottleneck. Musing about LOGISTICS. *THE TUNNEL NETWORK* If we're talking about a city of 100,000 rats -- er, households, then you might have a link-and-branch system of ever-widening tunnels until the major conduits empty into the Exchange. I suspect that you would need a reasonably geologically stable city. THE OPERATORS You'll need many operators, related to the number of messages per hour. I'd wild-guess that 1 operator could reliably handle 15 messages per hour for eight hours. If each house is expected to send one rat per day, then that's 100,000 rats in 24 hours -- round that up to 4,000 rats per hour. So you'll need 270 operators working every day... maybe 150 of them during the waking hours, and the remainder divided between two night shifts. Or whatever! TRANSMISSION ERRORS For various reasons -- for example, bad handwriting, or failure to pay one's bills -- the Operator may return rats to the sender with a "not delivered" tag. How sophisticated this feedback system becomes depends on the efficiency of the system and the needs of the population. In particular: the more commerce that flows through the network, the more sophisticated the messaging system will become. THE OFFICE Note that if your peak work hours requires 150 workers, then assume you need perhaps 15 supervisors (?), a dozen or so troubleshooters (now there's an interesting plot setup!), and a triumvirate of Bosses to solve really big problems. Plus an above-ground Customer Support Centre with a row of customer service experts whose inter-personal skills rival your Department of Motor Vehicles. And their Supervisor. And a Director (who is too important to have an underground office). So this Central Exchange has airspace and workspace for maybe 200 people per 100,000 population. Maybe. Scale to taste. THE RAT STACK You'll need more than one trained rat per household: for example, the house will need one on standby for sending a message, but also the Exchange will want AT LEAST ONE on hand for dispatch. And this is where your city will scale its rates. If you order more than one Central Dispatch Rat due to the heavy volume of orders to your rat-packet-home-shopping-catalog, you'll have a heftier utility bill. But anyway. Say the default is one Central Rat. That's 100,000 rats in 100,000 cages in the Exchange, probably sorted into some sort of rodential Dewey Decimal system. Which means the workers in the Exchange are skilled workers; not only do they have to be literate, but they also have to understand the System, and be able to FILE and SEARCH the system with a very low number of errors. Imagine the pain of a mis-filed Rat that gets dispatched, ostensibly to your home, but instead ends up at the Prime Minister's estate. We are not amused! RAT HOLDING As an aside, the Exchange will not want to immediately return any rat to its home: if the Exchange's cage for that home is currently empty, they might want to hang on to it. This is where errors will happen, because someone's mis-filed Rat will cause another household's Rat to be held at the Exchange. PROBLEM MITIGATION Thus you will need a Rat Mitigation Strategy. With a skilled workforce and reasonably efficient checks, this will be minimized, and therefore just a cost of an efficient network. In careless cities that have cut back funding, hilarity may ensue. Toss in at least some paranoia or threats about a Virus being released into the network, and there will occasionally be political and popular backlash, but if the network is really invaluable, such problems will be paper tigers. In the paper RPG culture, this is what we call a "plot hook". Assume that occasionally a householder will end up in therapy due to Rodent Anxiety. This is what I call "local color". SECURITY Finally we have the fact that such a network, if efficient and effective, will be quite valuable to a city... and therefore it is a single point of failure that needs to protect itself against hostiles. So expect to have security forces -- or just security theatre -- posted there permanently. Perhaps you could place the Exchange close to a military barracks, for a "free" level of security. [Answer] This would fail on many levels. In order for this to work for any time at all, you'd need to deal with any cat population. Upon doing that, the population of ALL rodentia would explode. They would then attack the food base, and rats are not picky about what they eat. Your trained ones might be able to be handled, but all the others wouldn't. Then, there's the whole privy matter.... These are a few diseases from poor sanitary conditions, and rodent borne illnesses. Dysentery. E-Coli Plague Hepatitis [FULL LIST HERE](https://www.cdc.gov/rodents/diseases/direct.html) And every other disease related to poor sanitation. This would be a good way to introduce a civilization that crippled or killed itself, but not a good system of messaging. [Answer] You're limited by the rat's attention span. It isn't that they aren't trainable (in fact their memories can be very long indeed), it's that they're easily distracted. While they might memorize the route, they might get distracted by other things along the way and forget about their task. The other thing about training is that you might need people in/near tubes to train the rats. One central place might not be best. Instead, there might be a series of central places covering a particular area, and then each gets handed to the next place and so on. I think it's going to be a lot more complicated than just one place, because the routes have to be short. Moreover, you are going to have to build hundreds of miles of specialized tunnels for your rats, a huge expense in infrastructure. There has to be room enough for the rats to pass each other, but not so much that they might get distracted. Other logistical problems, if there are specialized tubes for the rats--clean up. Rats will pee and poop as they go, so someone will have to clean that up. They are also going to end up being more of a vector of disease because people handle them more. [Answer] Possible point of failures: * predators: rats running up and down will attract attention of predators, possibly terminating the transmission. Example of [predators](http://automatictrap.com/blogs/news/5-natural-predators-of-the-rat): weasels, cats, owls. * pheromones: a single female on the season might distract ordes of males, rerouting the transmission to unwanted directions. * latency: in cases where a certain address is highly involved in communication, it can ran out of carrying rats (either to send or receive). This would end up in a denial of service type of failure. [Answer] As Mentioned to Problems with this are many-fold. I will try not to be too redundant. The main problem I see with this is that the cost and work required to train/maintain/staff and problem-solve this are huge. As someone already mentioned the cost of hiring skilled clerks/trainers to maintain all this seem way too inconvenient. Bottom-line I just don't see this being more effective then its main competition. Human runners, which have been used for millennia for their speed, and ease of use. No real education required. A noble house having their own personal messenger, that is also just a serf/slave is way more convenient and cost effective, then this complicated "Rat System" [Answer] Well, for one roman plumbing doesn't quite work that way. all the waste didn't go "back to central" it just went out into the country towns which used it for fertilizer. So I suppose you could use rats in the clean water pipes. Though that isn't a lot better than rats running in black water. Maybe rats could run on the streets? After all, Romans are known for roads as well. The rats could have a central dispatch per neighborhood. And a larger regional dispatch that uses people to go from neighborhood to neighborhood. After all rats are relatively intelligent and would probably be able to be moderately reliable at delivering messages if they are cared for properly and like their owners. [Answer] It's probably not worth the hassle of even training them because a rat's lifespan is about 12-24 months [Answer] This has all the pros and cons of homing pigeons And therefore, it's believable. Homing pigeons were occasionally shot by hunters, killed by eagles, didn't end up where they needed to go... but the system worked for what it was intended for hundreds of years. Pros * Cheap and easily replaced * Highly trainable * Reasonably hard to stop once in flight Cons * They have the brains of pigeons * They need to be fed, and you can't let them do that on their own or they go feral * They don't produce a high-quality fertilizer Having demonstrated that the idea works in concept, what remains is to use the concept's strengths to move your plot along and it's weaknesses to inject humor into your story. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 6 years ago. [Improve this question](/posts/70086/edit) I am making a video game on-board an old, creaky, leaky space station, which is forgotten or mostly not cared about, drifting around some moon/planet, with a single lonely, weary astronaut on board. I want it isolated and introverted, thoughtful and wistful. A bit like the movies Moon, Silent Running, or 2001 (although not forgotten about, its protagonist is isolated and lonely). The technology level of the space station is highly realistic, and quite primitive, maybe a bit like Mir. An onboard garden would be ok. Clunky switches and knobs are preferred over holographic displays or touchscreens. My question to Worldbuilding community is HOW and WHY the station and astronaut came to be in this situation... what events transpired to put him there (and then passed him by, leaving him mostly obsolete?). A core issue I have regards financial realism: How can I justify the expenses and mission importance of placing a manned station somewhere, only to let it fall into obscurity? The best answers will support the intended atmosphere, and invoke feelings of distance, isolation, and especially the fact that the rest of the world has just moved on, leaving this poor astronaut obsolete. Good answers will not make the astronaut special in any way, he will not be the star in a tragic mission-gone-wrong, nor will he be the victim of unusual circumstance. He's just an ordinary joe stuck with a job no one else wants to do, and pretty much abandoned due to lack of interest in his situation. My core problem is that real space stations are expensive, and require regular resupplies, and so are not very likely to be forgotten or abandoned.. Good answers will explain a way around this economic difficulty. Good answers probably don't involve him or the ship being very important in the past. Sure, there would have been good reasons for him being deployed in the first place, but good answers explain how and why these reasons faded and became uninteresting. Not broken, not lost, just uninteresting. Good answers don't involve him pining for home, don't draw attention to home and invoke complicated thinking about home. The astronaut is not trying to escape his fate, he is just doing his daily routine, performing maintenance, but he has accepted his hopeless fate, still performs his role out of a sense of duty, and that's it. Good answers don't invite much speculation into the outside world, and in fact the more boring the answer the better. Plausible shifts of corporate or political interest would be very suitable sources of reasons, as is having the job he was initially sent to do become meaningless, but they keep him there anyway, 'just in case'. The astronaut isn't about to die. The station can keep him alive as long as he works on its maintenance, which he does. Good answers place the astronaut in a timeless, unchanging existence. An occasional message from mission control, and regular automated supply drops are permitted. It is ok with alternative timelines, earths and histories, etc, but the technology in use should be clunky and old, but reasonably realistic. Higher levels of technology are acceptable elsewhere in the solar sytem, as long as its nowhere near the astronaut, and could even be used to show how everyone else has moved on, leaving the astronaut behind at his post. Bonus points if the station is located somewhere with a beautiful view (like Saturns rings). [Answer] # Generation ship derelict The plan — or rather: plans — were not grand, not glamorous, not even very well thought out. But with The Great Disaster looming — and inevitably coming — something had to be done. People tried all sorts of things: [mine shafts](https://www.youtube.com/watch?v=ybSzoLCCX-Y)... [suspended animation](https://en.wikipedia.org/wiki/Fallout_(series))... just calling it a day and [leaving provisions for whoever comes next](https://en.wikipedia.org/wiki/Seed_bank)... and then there were the [Generation Ships](https://en.wikipedia.org/wiki/Generation_ship). Everyone was scrambling for survival and desperately building on what they thought might save them. With The Disaster™ coming closer, things deteriorated. There simply was not room for everyone. Some would definitely not be able to save themselves. Conflict broke out. Not just between countries, but also some very weird ones happened... "Either you let everyone of Prime Space Parts Corp. come along or you can just forget* that delivery of life-support systems".* "We are sorry, but your shipment of tunnel boring machines has been cancelled because... well... not to be rude but quite frankly: we decided we need them for ourselves. Your payment has been returned to your account. We advice you spend it quickly, while there is still something to spend it on..." So these plans met with varying degrees of success. By the time civilization crumbled, some projects had been quite successful and managed to save a significant amount of people. Some failed miserably, littering the planet in a state of half-completion. And some were left in a state of some readiness, but never actually used. And this is where your hero finds themselves: on a Generation Ship ready to receive tens of thousands of people and ferry them to the nearest Earth-like planet that your hero scouted out for them. It was just that when your hero came back to our solar system, and could finally communicate with Earth again, it turned out that it was too late. The ship was there in orbit around Titan, far enough away to stay hidden from those that wanted to try to steal a ride with it. It is stocked up and ready, with ample supplies. It is not very... well... science fiction like. Some would call it crude and rather squalid to be honest. But it is rugged, and made to hold together for quite some time. ...as long as you do not try any fancy interplanetary maneuvers that is. Doing a long smooth climb out of the gravity well of Saturn and then out of the solar system is all fine and well. But trying to dive deep into the gravity well of Sol and then getting into orbit around Earth, dodging the Moon on the way: no. Just... no. Once approaching the gravity well of the destination star, the idea was that that the ship would get itself into parking orbit among the outer planets and stay there. The refugees would then ferry down to the inner planet(s) with the smaller shuttle transports that brought them to the Generation Ship in the first place, and that then stayed docked to the bigger ship. It is just that they never got that far. Before the shuttles were built and launched things had gone too far. They did not even have any crew on this big ship. No engineers to run the engine room. No officers to steer the ship. No navigation experts that know all the tricky business of plotting a course for the behemoth of a ship. Your hero knows how to pilot a small scout ship just fine, but it is nary impossible for them to make sense of this huge ship, let alone try to pilot it. Oh, and was it not just incredibly unfortunate that [some nitwit had managed to read the schematics for that one docking port wrong and gotten the polarities reversed](https://en.wikipedia.org/wiki/Murphy%27s_law), so that when the power supply from the Generation Ship hooked up to your hero's scout ship it blew out every circuit breaker on it, leaving them stranded on the Generation Ship without any means of leaving it. [Answer] # Punishment or Quarantine He doesn't really have to be alone, just be alone for all intents and purposes. His room/ station/bubble, looks in one direction only. There maybe be others, but he cannot see them or hear them and has no idea they are there. He/They disobeyed orders, got into trouble with a superior/have the AIDS of that time -- whatever fits your story. He still has a job. He has been given just enough hope to believe that one day, they might promote/cure him.. So he eats his tired rations and watches the whatever. He collects the data and sends the information every so often to Base. He has no idea how there are rations or water, but there are. [Answer] ## Looking for fame/fortune may be risky Centuries ago people will sail with boats to explore new lands. Your story is just a shipwreck survivor, a space Robinson Crusoe. ## Humans are good in unexpected situations Space exploration is going to be expensive and risky. The auto-pilot won't work in all cases. [Answer] WAR1 can always be used to isolate things. Have the country/countries running the station getting involved in a war with (an)other country/countries. As resources will need to be redirected to the war effort and keeping the nation(s) secure, your space-station will be switched to low-power-mode. Astronauts aboard will get the new tasks of serving as orbital reconnaissance - they have to monitor the enemy from space and keep an eye out for any spy satellites and similar space-faring-objects. Supplying your space-station with supplies shouldn't be that difficult as a one-way launch will be comparatively easy (just shoot a rocket with food and parts up to the station2). 1Hooo Haa! What is it good for? Absolutely STORY! 2Well not necessarily that easy, but comparatively more easy than schedule regular missions involving actual people opposed to less valuable stuff [Answer] It was once the hopes of humanity to build a space settlement. A series of accidents killed the crew and the project got discarded. It was too costly to begin with. Thus the dead is left on the derelict station. With comms down, nobody is aware of single survivor of the accident. With automated life support designed for 10s of crew members, the system will be able to support him for many years to come. Even though the food will become an issue in the long run, experimental greenhouse could provide enough food for one person. With nothing left to lose, he would continue the original scientific pursue he has started with. Not for others but to keep himself sane. [Answer] Two things that I could think of: ## Accident The station is not quite a station as it doesnt orbit a planet, but was made to explore the outer solar system. He was working in a part of the station, while all other were in the communications room when an asterioid hit that room and killed all other and the antenna with it. Now he is in this space station drifting outwards to reach his destination (some place in the outer solar system) alone, without the possibility to communicate. Food is grown on their farm that was just made as an experiment, but with onlyone person left he can live from it. ## Observation Post The space station was set up long ago to monitor the sun / a planet and now is just sustained by one person, as the human race is a spacefaring civ and does not need the station anymore but does not want to leave the sun / planet fully unmonitored. He gets some food from time to time and some other supplies, but because he is in a place that is not frequently visited and uses old tech he has very little conversations. He might nee to write a report once every week/month/year (even less frequent maybe). [Answer] # Routine inspection gone wrong It all started out as a standard routine maintenance mission, planned for 2 weeks. A ship was supposed to pick him up and return him safely. In fact, the protagonist wasn't the only one there, but also a second engineer. After two weeks the taxi didn't show up and for worse, the companion went missing somewhere\. And worse: The supply (oxygen, food, water) brought with them was only enough for two weeks This leaves your protagonist alone with two mysteries to solve and a struggle with resources. \Why the second person? In a critical mission you don't send a single person. [Answer] If I understood you correctly, you need to somehow answer, why he is all alone with none or minimal support from the planet. * It was a top secret project, that lost most of its financing - We still fancy this top secret mission, but we cannot afford more than one resupply rocket a year. Good luck - your loving and strong nation. This would answer why he gets no attention from public. * Kessler syndrome - When number of space debris becomes so high, that it uncontrollably collides and creates even more and makes space travel near to impossible. While the station is on higher orbit, he might be safe there, but trying to return would be statistically suicide and getting resupply rocket, only one out of 4 makes it through, making resupplies very expensive and rare. [Answer] He's a light house keeper. The 'station' is a navigation point, or a hazard warning. He's manning it, because ... no one wants the "light" to shut off, and so you need someone there to light it, fix it etc. But as the human failsafe on an otherwise mostly automated environment he can have as little - or as much - to do as you'd like. See also: [Beacon 23](https://www.amazon.co.uk/Beacon-23-Complete-Hugh-Howey-ebook/dp/B0151HYRCS) [Answer] There's two things I can think of right off the bat: # Cost It might be too expensive to bring this guy back - one-way supply drops are of course cheaper than a two way. I'm not sure this idea has much in the way of legs though as you'd need to afford many supply drops # Injury If the astronaut has some kind of brain injury or something that would kill him as part of an attempted return to earth (exploding embolism for example), then he'd be stuck in orbit without much hope of a return. This could inject some sense of peril for your astronaut in terms of reliance on drugs and aversion to any sudden movements. He's a bit of a ticking time-bomb. He wouldn't like the stresses of FTL travel either, not one little bit.... [Answer] He's the first and only person born in space. Developing in microgravity rendered him unable to ever survive on Earth, as became obvious while he was growing up. Heart too weak or something. (optional: disabilities also relevant in microgravity; visible deformities) Within his lifetime, manned space exploration was cut back again an again, until nothing was left. (optional: robot space exploration is thriving, with more advanced technology) Nothing, except for him. Being unable to survive on Earth precluded his return. He's maintained mostly as a charity case and PR disaster avoidance, but at minimal expense, which is way too expensive already. Nobody's going to upgrade his habitat. [Answer] Just because this space station isn't super-high-tech, doesn't meant super-high-tech doesn't exist; it's just that the station is as old and clunky. In fact, it's really, really old; it's been there for a century at least. It used to be a bustling mining station, before the last minerals were eked out of the system, and everyone left. ## Function The station is a passive way-point beacon, originally built as a mining platform. The station was paid for a thousand times over by the mined material, but once it was gone, there was no need for the station any longer. It was converted into a passive beacon, a low-power radio that only activates when other radio signals approach, to tell travelers that the nearby area (probably asteroids) is very dangerous to travel through. As a mining station, it was built to be tough, so it can survive asteroid showers and solar flares; it can also hold a large number of human miners. As a converted beacon, most of the station was stripped of mining equipment, or at least the most expensive and easiest to transport, leaving a nearly empty hulk. But not a dead hulk - the systems keep running, to keep the beacon lit. ## Supplies As a station holding hundreds if not thousands of miners, the station is extremely overstocked for a single person. Water and atmosphere are provided through automated systems; there is plenty of canned food, and probably room for a hydroponic garden or twenty. The station is built to be durable, withstanding both drunken miners and drunken engineers, so the supply systems are redundant and unlikely to fail, outside of a cataclysmic event, and plenty of parts are laying around. ## Communication A beacon doesn't need much in the way of communication; it doesn't even have a long-range radio (well, "long range" on a solar system scale), just its "short range" warning broadcast. If the plot needs it, an unmanned drone can transfer new firmware and receive any error messages from the station on a recurring basis; that allows the astronaut to leave a "message in a bottle" (or rather, an error log) for others to find - and perhaps long-term contact with a mysterious person, somewhere on the other end of that drone. ## Arrival How did this station come to be manned by a single astronaut? Our hero has the (highly illegal) job of collecting leftovers. He travels from one abandoned mining rig to another, finding the last grains of mined minerals, left behind when they were cheap, but in high demand today. He makes a good living, but he's not in it for the money; he's just a loner. At the station in question, his ship malfunctions. Through careful engineering, he manages to arrive at the station, finding breathable atmosphere and warm, if somewhat sparse, living conditions. Now, he's alone; in orbit around a breathtaking (but lifeless) planet, with nothing but a huge space station to explore and maintain. According to the logs, he's the only ship that's come close enough to need a warning in decades, so he's unlikely to be picked up by another ship. And the dated station doesn't have the parts he needs to fix his own ship... or does it? [Answer] One option might be that he is an overseer for a private enterprise that has some kind of economic interest in the station. Maybe he is on a long contract for them (ten years maybe?) as it's expensive to ferry people back and forth, or the company that put him there has since then got defunct. The difficult part would be to decide what kind of economic activity it is. Possible mining of fusion gasses from Saturn or some kind of asteroid mining operation. If you allow basic but decent autonomous drones that does the work it may be enough. In a lot of cases the drones don't need to be very advanced and can thus seem like basic tech. [Answer] I guess most reasons for abandoning someone in space would be financial/political, two examples. ### A Space Race and the collapse of a super power This could be very similar to the [Space Race](https://en.wikipedia.org/wiki/Space_Race) that happened in the late 50's and the 60's between the USSR and USA. And like then, during this race, one of the super powers collapses. In this case, our astronaut (or kosmonaut) is stationed on a Mir-like space station during the collapse. Shortly after, the space ship capable of transporting crew back to Earth's surface is launched, however, in the chaos of a regime change standard protocol is not followed and the ship explodes on the only launch pad large enough for crewed missions. The required repairs to the launch pad are too expensive for what remains of the super power. While still barely being able to fly (much cheaper) resupply missions, years go by. The crew transporting ships are neglected and degrade. Ultimately becoming incapable of ever flying again. [Example](http://www.boredpanda.com/abandoned-soviet-space-shuttle-program-buran-baikonur-cosmodrome-kazakhstan-ralph-mirebs/). For whatever remains of the super power, politically it is not an option to leave our astronaut to become the first person to die in space, or to let the remaining super power retrieve our astronaut (and the docking procedures are imcompatible anyways). So now he'll have to wait for the economy of the former super power to improve and for them to rebuild their manned space program. ### Search for minerals Early measurements indicate that it's likely that there are rare minerals/metals (iridium, platinum, etc.) in the moons/discs of Saturn, so a company sets out to mine these. Our astronaut is the first to make it to a research station to further investigate the existence of rare materials, only to quickly discover there are none at all. The program is all but scrapped, the company that ran it focuses on other ventures instead. If they could, they would just abandon him, but that's very much against the law, incur heavy fines (and prison sentences for management), and mean lots of very bad publicity. So they just do the absolute minimum to keep from breaking the law in the hope someone he'll die cause of his own mistake or some freak "we couldn't possibly account for that" accident. [Answer] Option one: He didn't start out at the station. He merely got there by accident. The station itself has been abandoned long ago for being to primitive and is now just a forgotten relic of old times. The Astronaut may have run out of fuel or have had technical issues with his own (advanced) ship. His ship may have exploded and he barely escaped or maybe nothing on his ship works but [stuff that is to advanced for the space station, but is needed for survival/other reasons]. Option two: The station got lost. The astronaut was working on the station and something went wrong. The station lost its orbit and was flung out into space. The technology of the station builders is not advanced enough to catch and return it so they can not help. But maybe (if neccessary) they build one or two rockets to catch up and deliver some supplies while the station is not that far away. (Catching up is much easier than catching up and returning (see <https://what-if.xkcd.com/38/>). [Answer] Major accident of the rocket used for manned flights 1. Accidents like those with Antares, Falcon etc. happen all the time. One day, an accidents happens with a rocket that's carrying humans to that station. 2. A big investigation starts, during which this type of rockets is not allowed to fly. Let's assume there are no alternative to that rocket that may kill people. 3. Until the end of the investigation, people on the space station will only be visited by cargo ships. It's quite realistic. The Soyuz rocket is used for both manned and unmanned flights. Imagine it explodes during an unmanned launch. Now we can't travel to the ISS with Soyuz vehicles (because they use the rocket that's exploded), Space Shuttles don't fly, and private vendors (SpaceX, Boeing) haven't yet finished their manned vehicles. The only option are the Chinese, but a) NASA doesn't want to cooperate with them and b) if they did, it would take a lot of time to make the systems compatible (see the Soyuz-Apollon program). [Answer] A nearly automated fuel station on Titan combined with bureaucracy I remember a plan to colonize other planets by building a fuel production facility on the moon with a mass driver to launch fuel to spaceships. You could easily do something similar on an asteroid or one of saturn's moons (Titan is be loaded with fuel). The station is necessary but far enough away to make manned missions very rare. It is mostly automated it just needs a person to schedule launches and do maintenance. supply drops would be mostly medical supplies and empty fuel containers. Maybe your protagonist works at such a station, originally there was so supposed to be a crew of four but cutbacks have whittled it down to one. Your protagonist should have been replaced by now but everyone knows it is a shit gig so every time they assign someone the task they retire or bribe a transfer. So your poor protagonist has been left there way longer than he should have been. bureaucracy screwing over a person is a lot more realistic than anything else, it happens all the time. I can image the poor soul trying to stay sane with television, intermittent time lagged internet, and tending the station garden. Imagine enough internet to play chess or once a day text messages, but not enough for anything more. The more I think about it the more Titan makes sense, fairly hard to get to, oceans of liquid fuel (hydrocarbons) so collecting it just requires a pipe and could be completely automated. The launcher could peek out of the atmosphere so you can have a single spot on the planet with clear view of the stars. You have wind and rain (methane), seasons, and a dense atmosphere so you can have a nice gloomy story atmosphere. You could even have some form of primitive methane based microbial life. It even gives you an interesting game mechanic, the poor sod would be paid but can't do anything with it, so I imagine he would spend it on bribing some dock worker to include a few special items in his scheduled supply drops, (at exuberant prices of course). things he can't get from the station farms or fabricators. Things like: beef jerky, chocolate, entertainment hardware, illegal software, hemp seeds, coffee beans, ect. [Answer] I think the observation perspective is likely your best bet (@C.Fe.). In the form of a waypoint beacon (as suggested by @Sobrique), or for some economic or military reason (@dot\_Spot, @OnePie, @David162795). So, here's my suggested scenario: Observation post is very important for (pick one or more of the following): * Scientific discovery X -proof of alien life, -possible alien artifact, -new phenomena which is initially very exciting but is only valuable after a certain amount of observations have been taken... -etc... * Military purpose y -the only least expensive & most effective way to monitor for enemy presence in each system surrounding the home system was with a manned station... -an automated production facility is hidden on the moon/planet the station is orbiting -the station is some sort of communications relay (or transponder beacon) but the minimal automation wasn't yet up to snuff so they manned it... (new ones are entirely automated) * Dangerous Phenomenon Z (which requires in-system monitoring for early warnings to allow for enough evacuation of a given near by system...) such as: -Super Nova -Catastrophic Growth of Black Hole(probably not very scientifically viable but...) -Monitoring of space fold nexus which if \_\_\_\_\_\_\_ and \_\_\_\_\_\_\_\_ line up means it could implode and destroy \_\_\_\_\_\_\_\_\_\_ or cause cataclysm \_\_\_\_\_\_\_\_\_ Space Station is: * Only partially automated external & internal hull repairs are pretty much automatic, most systems recycle everything well, astronaut has to take care of the plant growth for the respiration recycling to work properly, etc... * Checked on by automated systems all the time but very rarely by other beings Could lead to situations where the astronaut intentionally causes/doesn't prevent problems so they can talk to a real person * Physically quite remote * large enough to feel empty without someone else in it but small enough to cause some feelings of being caged in Astronauts Purpose is: * Originally of high interest/concern to the astronaut, now an obligation but sometimes hope for release * Possibly originally challenging but now very routine * Not that easy to automate (@ least @ the time the astronaut was sent) Last, the astronaut was led to believe they would be shortly done with their isolation and would be a hero/noted person in history. Now obvious they could be there a very long time Which fact suggests that the astronaut may not be as important as was originally claimed... Hope that's helpful [Answer] His home country of Whereeveryouwantistan, who rose to a Superpower in the year 20XX, is currently in a the grips of a civil war that has lasted decades. The few scientists left at mission control are on the 'good' side, and are trying to keep him going while waiting for order to be restored. The 'good' government still has 1 guy who believes that it is important to keep the space station going, but only has limited influence, enough to keep supply drops going, but not enough to keep it up to spec. [Answer] # They do not want to be found You could build a story around their motivation for not wanting to be found. Maybe they are running from some threat. Maybe they want to be left alone, being around people remind them too much of someone they lost. These are classic hermit motivations, I'm sure there are more original ones to be thought of. Maybe they are seen as a hostile alien by the station's owners. If they do not want to be found, the station also does not necessarily need to be barely functioning or empty. Maybe they are playing space barnacle to an active station, gives them an interesting perspective and challenge to not be detected. [Answer] ## Another war scenario Put the story in an alternate timeline where the race to space and the cold war continued for quite some time. As the tension grew up between the superpowers, there were some scientists who believed that scientific cooperation was the golden path to achieve mutual understanding and, ultimately, peace. There was the Apollo-Soyuz program, and right after that the race to Mars. Space agencies knew that a joint mission was the only viable alternative to send men to Mars. Or hero embarks on the first such mission. It's a four men crew: two astronauts and two cosmonauts, working together to give an example to the World. The ship is quite large, as it has to house the crew for a few years. In essence a small space station. It is also completely self-sufficient. After reaching Mars orbit, three men embark aboard a lander to explore the surface, leaving our protagonist alone. And that's when the Third World War starts. Our hero witnesses on the intercomm his crewmates fighting each other, as they now consider themselves enemies. “No! Not them!” he thinks. He unsuccessfully tries to talk them out the fight, but they just end up killing each other. The war was nowhere near the total apocalypse many feared, and most people survived. Yet there were many cities destroyed, and a huge amount of suffering. No one won, and there wasn't even an official peace treaty, but the fight stopped nonetheless, kind of like between our two Coreas. No one on Earth still believes in cooperation between the former super powers, and everyone is busy mourning the loss of beloved ones and struggling to rebuild the civilization from it's ashes. The space agencies do not exist anymore, and basically no one cares about the lost astronaut. Our hero is an idealist. He really believed in his mission, in scientific progress, and in the spirit of international cooperation. He cannot go back, as that would require carefully calculated flight plans sent from Earth, but he has all he needs for growing his food and wait until one day, maybe, things get better on Earth. He does know it will take a very log time. He can catch glimpses of radio emissions from Earth with his high-gain antenna, but no one would answer his calls. So he does what he was sent there to do: he collects scientific data and sends it back to Earth. Maybe someone is listening. Maybe a radio amateur built an antenna out of scrap metal, but he cannot afford the electric power needed to send an answer back. Our astronaut also saves to tape the most important data, but he must be selective, as his stock of blank magnetic tape is limited. One day Earth will know peace again. One day space agencies will resume operations and he will be called back. One day the data he is collecting will be useful. One day... He has hope in a brighter, albeit distant future. Hope is keeping him alive. ]
[Question] [ ## Background: Following the development of faster-than-light technology, humanity has spread across the stars and encountered many kinds of alien life. While the galaxy is mostly peaceful, occasional wars do break out, and piracy is an issue. ## The Tech: All groups use an FTL drive based on the same basic principle: the drive creates a wormhole at the front of the ship and pulls it over to the rear of the ship, depositing it at the target location, with it seeming to an outside observer that the ship had simply disappeared from one place and reappeared in the next. In addition: * The computer power (and therefore time) necessary to calculate a jump increases with range, up to a rough maximum of ~ 30 light-years * Gravity wells also render the calculations more complicated, meaning that it takes progressively more power to jump the closer a ship is to a planet or other large body * There is no warning ahead of time at the endpoint that a ship is about to jump in- it's just there * Any material present at the endpoint is displaced to the origin point, preventing two objects occupying the same space ## Situation: I am an Admiral tasked with defending Earth from possible attack. While most avenues are covered, what really worries me is the possibility of a force sneak attacking by jumping in right behind my defenses, firing a few salvoes, and then jumping away before my forces can respond. Is there any way in which I can avoid or minimize the threat of this possibility? [Answer] # Make it too dangerous to jump in Suppose the inner solar system around your habitable planet has a series of minefields. These mines are placed in pseudo-random orbits which are changed on a weekly basis. The mines are only activated by a nearby wormhole opening. This won't interrupt local commerce, since intra-system ships won't use wormholes. Commerce with other systems will have to use pre-approved jump points at scheduled times and designated places so they won't activate the mines. The mines themselves should be designed to operate at low temps, and be made with low albedo, low emissivity materials, so they are hard to spot, even by a scout ship in the outer solar system. Moving the mines can be done externally, using mine tenders or tugs, so the mines themselves have no active power generation and negligible heat signatures. [Answer] The best defence is to use a variation of the drive to get rid of FTL sneak attackers. if the wormhole drive works by creating a wormhole at one point and it moves over the ship to allow the ship to jump. Place a series of wormhole generator orbital stations around a planet you want to defend. When a sneak attacker appears, activate the wormhole generator and project a wormhole in the direction of the pirate vessel. Once the wormhole passes over the vessel it will jump to what may be a predetermined destination. The pirate ship will jump to somewhere far away, which can be up to twenty or thirty light years away. The wormhole projector can be preprogrammed to make attackers to jump away to somewhere else. As an extra protection, the Admiral can station missile and laser batteries at the predetermined arrival point and immediately a pirate vessel arrives they can blast it to good old fashioned atomic dust. [Answer] Please read my "FTL implies causality violation" comment on the question itself before reading this answer. Securing one's backstory is safe from temporal interference by FTL travel is quite difficult, especially if the universe has an unstable history (I.e. grandfather paradoxes are legal). For a hard-science sci-fi space empire where paradoxes are legal, read "Singularity Sky" by Charles Stross. For a hard-science world where physics allows time but not grandfather paradoxes, read "In the Garden of Iden" (yes, I spelled that right) by Kage Baker. Pick your physics. The only defense against FTL in a paradox violation cosmos is constant vigilance against every entity capable of FTL travel. Really really hard. You probably need some serious intergalactic UN-type entity or a technological elite that enforces FTL discipline on lesser species. In a more rational universe, defense becomes more viable, but you still have limits. The enemy cannot just teleport into your history and conquer your people before they discover space flight. But they could fly into your planet's formative years and hide a giant bomb that doesn't go off for several million years (assuming they have the materials to build such a long-lasting device). So after all of that, the best defense, in my opinion, is the same defense the USA and USSR used in the Cold War: mutually assured destruction. Every FTL-enabled political entity (planet or culture or species) is coerced by all the others to have a genocide bomb planted on its homeworld/main HQ that will be detonated if that entity abuses FTL during war to perform time travel. Or there are many variations of dead-man-switch to ensure détente. Pick your favorite. After that, all the defenses discussed by other answers come into play. [Answer] As a defense contractor, I would like to sell to the Earth Space navy a device call a gravity well projector. This projector uses the same wormhole technology used in FTL but rather than moving a ship, it creates a space-time warp that is static in space. Which would in effect create a wall against any FTL vessel, similar to a FTL vessel hitting a gravity well. If enough of such projector were use (purchased), it would be possible to create a fall all around earth space... leaving on well defined corridors to be used for military and commercial traffic. I would also recommend the good Admiral consider purchasing our FTL enabled city ships.... which will always be motion. If humanity can be persuaded to live on city-ships, our population will be mobile. Able to seek new resources and be more resistant to attack. It is far harder to hit a moving target than a static one. [Answer] # You can't The reason is down to variants on all the examples that follow and the fact they present absolutely no risk to the party employing them. > > * Any material present at the endpoint is displaced to the origin point, preventing two objects occupying the same space > > > # The Wormhole Missile This is the most conventional weapon in this list. It barely even needs a warhead, just a suitably large displacement. I target your capital(ship) and let it go. A partial hit is fine as it just transports half your capital(ship) to my location where it can be finished off. Any actual warhead in the missile can finish the job at the other end. # This drive is the ultimate toy for pirates The same applies to your valuable cargo. I target the cargo ship, then use a drone or my last captured ship with a souped up drive and just dump it on your cargo carrier. Your cargo is now in my controlled space and you're too busy dealing with whatever entertainments I've put on the ship I sent. To prevent this sort of thing you need some way to detect and prevent the wormholes from forming. See Schlock Mercenary and the [Terraport Area Denial](http://schlockmercenary.wikia.com/wiki/Teraport_Area_Denial) which is the prevention option for a very similar drive technology. # A few more thoughts on (ab)using this drive technology. What happens if the field is shut off halfway through a transport? If half the ship goes then it leads to far more interesting options. Most of these are based on the fact that the drive has to transport a defined volume of space and anything in it rather than specifically anything in contact with it. If you enforce the latter option you'll be leaving behind anyone who jumped at the wrong moment, or gyroscopes held in magnetic fields for example Most of these can be happily planet based as they're not transporting the drive so you can use planetary grade power supplies. ## The pod launcher The drive runs for long enough to transport a cargo pod but the drive doesn't transport itself. ## The pod exchanger Similar to the pod launcher but actually swaps the pod with one left at a specific location at the other end. ## The Come Hither or Pirate's Friend A drive with a hacked field generator that transports an empty space rather than the ship. It simply transports a volume of empty space, gas cloud or otherwise and returns whatever was in the location it was transported to. This leads to ## The Kidnapper A much harder device to work with, but based on the pirate's friend it's able to extract the command staff off a ship by transporting a volume of air to their location and returning the person. [Answer] So a problem is that instantly appearing in a system gives you tactical advantage. Your passive sensors immediately pick up everything in the entire system. Meanwhile you only show up in an expanding light speed sphere. So you can jump in, detect and shoot, jump out before retaliation. if you park your fleet in deep space it is cheap to jump there, and accurate. Then you execute a pattern where ships jump into the system and systematically destroy all defenses with zero chance to fight back and jump back to the fleet location where they can quickly compare data for the next jumps. The only defense here is constantly jumping defenses. Even then, your rules makes it impossible because the high value planetary targets cost more energy to jump around near. Other posters have postulated some magic devices to prevent the jump in or make it harder etc. A simpler idea is that jumping causes disruption in systems and leaves you vulnerable for a few seconds or minutes which gives defenders a chance to defend. You can scale it with gravity just like your jump cost. [Answer] The massive amounts of energy required to create the wormhole bubble is released upon arrival as a massive EMP. It is possible to shield satellites and defensive structures around the planet given that they tend to be far away (due to the nature of space). Earth's magnetic field would also protect it from any effects. However, since the warp bubble surrounds the entire craft, no system can stay online after such a blast. This also means that you cannot have any charge left in your capacitors, else they might blow. Thus you arrive with no power and no backup charge - easy pickings for any defence force. Your ship would require some time before it comes back online, and a lot of time before it can recharge it's capacitor banks in order to jump away again. Hence guerrilla tactics are impossible. [Answer] This very much sounds like a situation in which [M.A.D.](https://en.wikipedia.org/wiki/Mutual_assured_destruction) applies without any extra special considerations. Just make sure that it's understood that any enemy that uses such tactics against you is going to find the same tactics used against them, either by you or your allies. Build and maintain an arsenal of FTL enabled nukes, preprogram the co-ordinates of various enemy home worlds,send them out into the void of space so that nobody knows where they are, then sit back and watch ~~an interstellar Cold War~~ galactic peace unfold. This doesn't require any further stretching of the laws of physics: it's just politics and sociology from this point on. You can expect combat between large nations to split into more codified 'official' conflicts and plausibly deniable attacks that no nation is willing to own up to, but which aren't large enough to cause a major diplomatic incident. When an outsider group emerges that threatens the stability of this system you can expect all the nations to work together to neutralise the threat, fearing that once the cycle of destruction begins nobody will be able to stop it, and every world will end up devastated. Of course there will be objections, but those people are just luddites who can't see the benefits of having galaxy-wide destruction looming over their heads at all times. [Answer] It’s not just a matter of computing power: Using the approach that [all wormholes give transit that’s considered simultaneous in the same special reference frame](https://worldbuilding.stackexchange.com/a/47038/885), you will naturally have problems making a jump within a gravity well. Due to GR, the wormhole mouth will not experience time at the “correct” rate and this causes severe limitations in the size of body that can be transferred. You can use GR to drive a useful set of restrictions for your story, and impose extra logistical issues that prevents too abrupt turns of a plot. So, you will only have ships arriving far from the planet. Small durable message capsules can arrive as close to the sun as the planet is, but still some millions of miles from the planet. A battleship would have to appear well past the orbit of Neptune. The problem is that it could appear from any direction, and there is a huge area to watch. Ships will be stealthed. Defense will concentrate on detection as early as possible. [Answer] Place artificial gravity wells on strategic points. This technology may be similar to the [Gravity Well Projector](http://starwars.wikia.com/wiki/Gravity_well_projector) in Star Wars, with a significant difference because of your physics. The SW-GWP interrupts the hyperdrive in Star Wars vessels, forcing them to drop to normal space. Your technology will work slightly different, it'll alter the location where the wormhole will pop up, forcing the ship going through the wormhole to end up some AEs away. On the other hand, opening a wormhole to fly through is very energy consuming, so it might not be the best idea for the attacker to show up to close to the target, because the flight used up 95% of the ships power, so it takes time to start up weaponry and shields. This is similar to Sun Tzus "Art of War" Rule to be first on the battlefield, so you can recharge and prepare for battle. [Answer] You use the FTL drives as weapons. The tech definition doesn't mention rules about the edges of the wormhole endpoint surfaces, so the wormhole generators can be used as powerful weapons by swapping a partial volume of an enemy ship with some other volume, be it empty space very nearby, a different volume of the same ship, or some volume of another ship in the same fleet. This assumes that the "originating" wormhole endpoint can be generated entirely outside the generator. (The "destination" wormhole endpoint obviously can be, so it's reasonable to assume the "originating" end could too. There may be no reason to consider the two endpoints as ordered; they are simply swapping. Many other answers assume a generator at some "external third point" can cause a wormhole between two points.) Because the distance between the wormhole endpoints is minimized, computation time is minimized, and it becomes a footrace between attackers' computers which possess the element of surprise but need to compute a jump of at least some distance in order to get away, and defense computers which must react to the attackers but only need to compute very small jumps - possibly smaller than the length of an attacking ship. (Bonus points if defensive scanners can typically identify the drive core and the bridge of all attacking vessels very quickly, the two preferred endpoints for a wormhole swap. If swap volume shapes can be tailored, defense may simply opt for shuffling numerous thin slices of attacking ships along their major axis like a deck of cards.) (Potential) spoiler for Vernor Vinge's book "The Witling", a note about prior similar art: > > Swapping volumes (instantaneously) is a key part of Vernor Vinge's "The Witling"; they called it a few verbs ending in "-eng", depending on whether they were using it for travel, slinging missiles, or scrambling opponents' brains. In that universe, the generators were the minds of most native humanoids on a certain planet, and both endpoints needed to be locations the generating person had witnessed personally at some point in his or her life. Any person capable of performing these acts would automatically protect himself/herself from being bodily scrambled - at least, while conscious. Difficulty of performing the swap of two volumes scaled with the volume swapped but not with distance. Velocity was conserved through the swap; that's useful for slinging missiles, caused them some trouble traveling rapidly about the planet, and could be a major concern for spacecraft, e.g. wormholing from the Western Spiral Arm to the Eastern Spiral Arm within the same galaxy. > > > If the defense can use the FTL drive tech as defensive weapons, then attackers could use them as well. Are the gravity-well rules enough to prevent this? Is conservation of momentum a concern - i.e. attackers warp in cold rocks moving at high relative velocity and don't need to plan for an escape? [Answer] Your solution is that your and then jumping away before my forces can respond is not possible. It's reasonable to assume/state that you cannot calculate your jump beforehand, i.e. you can only do the calculation at your place of origin for the next jump (local gravity and such need to be taken into account). If there is a minimum 'base' time for the calculation + as you say additional time necessary to calculate a jump increasing with range, the enemy is vulnerable for at least the base time. With that base time they can only make a very small jump (make something up), or they have to take their chances staying longer in order to make the calculations to get away a safe distance. You can work this out further assuming that your defense is faced outward from earth. Appearing in front of your guns would be stupid. So you have a second line of defense (can be smaller, can be earth based) in lower orbit than your main defenses. What this cannot prevent against is suicide missions, but assuming that the enemy comes from far away and has to haul along all his material, while your resources are only one earth orbit away, you will win a war of attrition. [Answer] Hm, I've thought about this before. My solution for this always has been to assume we also have the ability to create temporal-warp fields. Using that technology you could create a planet-wide shield, and the space between the outer shield and the upper most part the planet could be a temporal-warp field. You could manipulate this shield to let air-traffic in and out; closed otherwise. Now if someone makes a jump within that space they would be caught in the time warp, in which case you could then disable the field around the attacking ship. By then you could carry out a typical attack plan, leave, disable the warp field where the intruder ship stands let the ballistics take effect....or skip all that and simply create time-warp shears around the attacking ship so once they attempt to jump again its caught in the time-field and ripped apart. Speculation of course. The only problem is if they attach a FTL device to some 'super-nuke' or black-hole bomb get it past into your atmosphere. [Answer] > > The computer power (and therefore time) necessary to calculate a jump increases with range, up to a rough maximum of ~ 30 light-years > > > Here's the tricky thing. If its faster, and you're nearer, the defender has the advantage of being able to deploy units in reaction, and since its essentially instantaneous... Have a rapid reaction force. Jump into the projected path of the projectiles, hit them with point defence or decoys, jump them out. heck, you could jump an asteroid into the way, let it take the damage and jump it out. Lets munch this out a little more. Since you're fighting in friendly territory, have networked or predetermined jump sequences for the tour of each of your defensive craft. Have them parked near a big space station which sends them jump instructions calculated on a very bigass computer, so your reaction time is shorter. In a sense, don't bother about stopping the attackers. Make any attack toothless. Pre-calculating jumps makes things even more fun for the defender since they only need short range jumps inside a known gravity well. They don't need to flee, and they basically just need to menuver. If you have anything more than a hit and run, these tactics get even deadlier. Jumping from pre-determined jump point to jump point. Jumping an enemy ship into the line of fire of a missle they don't even see. [Answer] I will address this with a couple of points. 1.) There is no concept of direction in space, and ships would be designed and armed accordingly, likely with automated turrets covering the ship relatively evenly, with larger than usual concentrations covering sensative sections of the hull. 2.) Standard fleet formations would adapt to negate the risk of this threat. For example, fleets would be arranged in hexagonal-donut formations or circular formations, preferably with multiple rings, when not moving or patrolling. This way, no matter where the enemy jumps in, a significant number of guns will always be facing them. 3.) The risk of being "caught from behind" is negated completely if you opt for spherical ships evenly covered with turrets, and with all vital components being in the "core" of said sphere. Thrusters would be scattered around the surface as well, for sublight movement. 4.) Perhaps both the main weaponry of your advisary uses crap-loads of energy, which means certain things have to be taken offline upon engagement - including FTL. 5.) Your fleets could alternatively conpletely disperse evenly into your territory IF they could both cloak themselves in some way, AND detect enemy ships. 6.) You have some sort of "secret weapon", be that a simple technological edge, ancient "precursor" technology reverse-engineered, etc. 7.) Another "fleet formation" idea: Arrange your fleets in overlapping arcs so as to extend your field of fire as far as possible, and perhaps, if you are lucky and they are not, catch them in a major crossfire. 8.) Have some sort of targetted "jump jammer" that creates large gravity wells as soon as the enemy jump in. These would probably use a lot of power, and a plot point could be that they need an entire ship's worth of power to work - meaning that entire ships have to take their weaponry offline to devote their entire power to this task, and making the defense of such ships of paramount importance. 9.) If the combat involves projectile weapons or missiles, and if the majority of weapons are "guided" or "heat-seeking", you could fire a random salvo of your own missiles to give the enemy projectiles something else to hit. 10.) Primary weapons - the kind that can easily destroy entire ships in a single shot - cannot function in close-ranged combat. Meaning, they could probably do more damage in a direct confrontation, than a sneak attack. [Answer] You haven't mentioned anything about weapons in your universe, and I think that matters. # Use lasers... Friggin' Lasers! So here's a solution: big, powerful laser weapons (either built on the ground or on large enough space stations). This kind of weapon needs to be big enough (or have power requirements large enough) to be a poor fit for any (combat) ship\. The targeting lenses also need to be agile, to quickly track targets in the weapons range. Since such lasers don't use projectiles and can hit the target almost instantly, then while a suicide FTL attack is still possible, it's just that - a suicide attack. Anything that appears suddenly within the range of the lasers can likely get targeted, fired upon and blown up before they get a chance to jump away (I'm assuming increased calculation times due to planetary gravity). \- that's not strictly speaking a requirement. However if ships can fire projectiles at best, then said lasers can also defend against those projectiles. If ships can also be outfitted with potent lasers then their attack COULD potentially be organized well enough to fire on the defending lasers before they have a chance to respond... but this assumes that: a) defensive laser positions are all known b) despite just warping in attackers can fire instantly; didn't they just spend a lot of energy opening a mini worm-hole? ;) (I assume lasers need some power to fire, unlike missiles or some such) c) the attacking fleet has enough lasers to attack each defensive laser and destroy / cripple it [Answer] This isn't an answer that would help a particular admiral, but it presents a sociological solution: after the first two or three times we're hit by this kind attack force, we realize that remaining in large, centralized populations allows this attack to pose a genuine existential threat to said populations. The solution: a deliberate diaspora, using the same wormhole technology to keep people and resources (and culture) flowing between colonies of only a few hundred people each. All of this assumes, of course, that the amount of energy required to make these jumps between points in low curvature spacetime is very easily available and we don't have to seriously worry about running low on energy reserves. If we do... Well, this might be just what prevents serious attacks like those described from being a problem. The diaspora solution is also troubled by the fact that space is really big, and important resources are all clumped together in solar systems; the need for resupply runs, long term mining operations, or large agricultural projects would provide points of vulnerability. Smaller colonies would potentially be more vulnerable to a small number of heavily armed ships lying in wait. But I think this might be surmountable. ]
[Question] [ A rather simple question in my opinion compared to my typical: Why would a nation with Napoleonic age technology and weapons use axe bayonets over the more standard 'spear-like' bayonets? They were made so I imagine there was a rational at some point I'd like to understand. part 2: how could this rational carry over or make more sense in a world where a Napoleonic age empire of humans is fighting things like the monsters and races seen in Warhammer Age of Sigmar? [Answer] Axe bayonets do exist in history (most of them are decorative in these images but some are used as weapon, if I remember it was commonly used by Prussia/Germany or around there). From what I gather, one of it purposes is as a mix of boarding axe and gun (usually for a pistoler rather than long rifle type). Also it does well for cavalry mixed weapons from what I found (the third image below is used for cavalry, the upper one). And just like an axe it can help in hooking something or breaking wooden objects, maybe to break the enemy rifle too (it more than likely would destroy the wielder's gun barrel or the mechanism in the process but, perhaps that's not an issue because there's not enough time to reload anyways). Copy paste picture from my answer in [Best gun to modify into a monsterhunter weapon?](https://worldbuilding.stackexchange.com/questions/152619/best-gun-to-modify-into-a-monsterhunter-weapon/152622#152622) (and maybe some of the answers there can help you) [![enter image description here](https://i.stack.imgur.com/ZkR33.jpg)](https://i.stack.imgur.com/ZkR33.jpg) from <https://hugelol.com/lol/86852> [![enter image description here](https://i.stack.imgur.com/vTAMI.jpg)](https://i.stack.imgur.com/vTAMI.jpg) from <https://www.reddit.com/r/mildlyinteresting/comments/6eonme/found_this_combination_axeflintlock_rifle_in_a/> [![enter image description here](https://i.stack.imgur.com/XR83n.jpg)](https://i.stack.imgur.com/XR83n.jpg) from <https://ilovefunnythings.wordpress.com/2016/03/31/the-british-had-the-bayonet-the-germans-had-the-axe-gun/> [![enter image description here](https://i.stack.imgur.com/J5Xlp.jpg)](https://i.stack.imgur.com/J5Xlp.jpg) from <http://thegunsman.com/2013/12/axe-guns-gun-axes/> [![enter image description here](https://i.stack.imgur.com/W302r.jpg)](https://i.stack.imgur.com/W302r.jpg) from <https://www.reddit.com/r/ArmsandArmor/comments/bi13bu/a_silesian_flintlock_axepistol_from_1670_the_gun/> [![enter image description here](https://i.stack.imgur.com/F1N37.jpg)](https://i.stack.imgur.com/F1N37.jpg) from <https://www.reddit.com/r/ArtefactPorn/comments/5z5gvn/flintlock_combination_boarding_axe_and_carbine/> For why they use this against monsters, maybe because the monster's hide is too thick or hard for penetration using a common bayonet spear, so they use an axe instead to give more bite or hack or cut. [Answer] Part 1. Bayonets - no, at least as a real weapon. You see, bayonet is a detachable device. It just can't withstand axe-like strike without damaging it's mounting points (or barrel if it is plug bayonet) - even "normal" bayonets always had and have problems with that. If you try to make hybrid weapon (like in @Li-Jun answer) - you would had to keep it short, because axe larger mass will make it an unwieldy gun. If you would reduce axe mass to extreme, you come to sword-like bayonet anyway. And in napoleonic times there were just too little armor on the battlefield for poleaxe. And when it comes to just make in hole in uncovered body - simple spear is better then any other polearm. So as a toy- or art-weapon it can be done. May be pirates would use it (using axe as hook or support on a railing) mostly for "badass" look, but only as short "handgun". But axe-bayonet will certainly never go for something like musket. Part 2. Since axe-musket hybrid is a bad single-use poleaxe and a bad unwieldy musket - it would be far more logical to have two separate type of troops: one heavyarmored with poleaxes and other - no-armored, fast-running shooters (they do not even need any bayonets, if they are usless against beasts and dwarfs). Or you troops may be like russian [streltsy](https://en.wikipedia.org/wiki/Streltsy) wich were using berdyshes as close-combat also as a support for there guns (dosen't Kislev already has ones?). But this are far pre-napoleonic. But if you still is looking for some cool-looking weapons, you would need to make hybrid "shooting" poleaxes - may be even single-shooting. This "shooting" poleaxes would twice as thick as nomal ones and should have fast-removeable ignition mechanism - it will not suvive poleaxe fight and will mess a lot. [Normal people would not be able to handle them](https://www.youtube.com/watch?v=6k5SauImw9I), you will need unnaturaly strong guys.May be magicaly-modified? Or some half-humans? [Answer] These hybrid weapons were made because early guns took a long time to reload. In any realistic combat scenario a combatant might get one shot off, and then have to turn to close-quarters combat. Rather than dropping the gun and drawing a secondary weapon (ala "The Three Musketeers"), guns were crafted so they contained secondary weapons. Long, pointed weapons like swords, spears, and bayonets are most effective when used in organized formations. Combatants form a solid line, and an oncoming enemy is confronted with a thicket of sharp points that it has to break through. If you watch any World War I movies you'll see a lot of that: soldiers forming a line, firing off a shot or two, and then fixing bayonets to advance in unison. However, in disorganized hand-to-hand combat axes are more effective. They are quicker and more maneuverable than large swords (the moment of inertia of a long, flat blade is greater than that of a compact axe), have more cutting power (try chopping down a tree with a longsword), and need less room to swing. A bayonet in the same circumstances would be equivalent to a short-sword or dagger (with an uncomfortable long hilt). That would improve its maneuverability but drop its cutting power even further, making it ineffective against anyone wearing light armor, or any creature with a significantly thickened hide. There are a few 'sword vs axe' videos on YouTube that you might take a look at; it's kind of a meme. [Answer] In order to consider why an axe bayonet would be a good idea, let us first consider why a long spiky bayonet has been more popular: 1. Reach - if one soldier has a long spike protruding well beyond the end of the barrel and the second has an axe blade roughly level with the end of the barrel, the soldier with the axe is likely to be impaled on the long spike before getting within range to swing the axe. 2. Weight and effort - battle axes were light. Forget the illustrations of fantasy figures and the oversized (rubber) blades carried in poorly researched medieval-period movies - an axe that could be swung quickly enough to be effective in combat was a very light blade much thinner than the tools used to cut wood. Even with a light axe, though, the amount of effort required to inflict a fatal or disabling wound with a cut is much greater than the effort required to stab an enemy for the same effect. 3. Grip and balance - a rifle / musket with a spiky bayonet can be used effectively as a spear with the hands gripping it in roughly the same position that would be used when firing. An axe needs to be gripped with one hand close to the butt end of the handle with the other hand free to slide up and down the handle - this works badly with a rifle or musket due to the end of the stock being too thick to get a good grip and the trigger mechanism blocking the off hand from sliding up and down the stock. 4. Damage to the firearm - a rifle barrel and stock are strong in compression, resulting in a very low risk of damage when either stabbing an enemy or using a smash with the butt at close range. However, a series of repeated, powerful swings risk separating the barrel from the stock, breaking the stock or possibly even bending the barrel. Given all of these reasons why long, stabbing weapons are better, some or all of these must be negated in order for axe bayonets to be desirable: 1. Reach - the enemy of the axe bayonet wielder must not use reach weapons. Reasons could be religious / cultural as the tactical advantages of using weapons with long reach are overwhelming. 2. Weight and effort - the humans must be very strong and enemies must not be vulnerable to stabbing damage and enemies must be vulnerable to slashing / cutting damage and enemies must be vulnerable to musket ball damage. This is a really difficult situation to visualise - maybe the enemies of the humans are some kind of plant creatures that have no central circulatory system or vital organs to stab, the only way to defeat them is to cut their connecting tissue apart. (Which raises the question of why anyone would try to shoot such a foe with a musket in the first place...) A slightly less fantastic solution is that their armour is highly stab-resistant but can be cut away with enough slashes - armour made of poorly-stitched plates, for instance. 3. Grip and balance - change the shape of the stock so it is narrow all the way down to the shoulder and give each soldier a socketed shoulder plate built into their uniform / armour to distribute the recoil force. Change the trigger into a recessed stud and try to work out a low-profile ignition mechanism. 4. Damage to the firearm - protect the firearm from shear force damage by reinforcing the bands securing the stock to the barrel and making the barrel heavier. Accept that this will make the musket / rifle even more heavy and consequently unwieldy as a melee weapon. Look to logistics to ensure that damaged firearms can be repaired or replaced as required. In summary - long spiky bayonets have lots of advantages over axes. The type of enemies and situations required that would allow axe bayonets to dominate will result in a radically different environment to the Napoleonic wars. [Answer] “Why would a nation with Napoleonic age technology and weapons use axe bayonets over the more standard 'spear-like' bayonets?” Well you’ve answered your own question, they are “fighting things like the monsters and races seen in Warhammer”. If the spear-like bayonets are ineffective at piercing the hide of the monsters you are fighting or the armour of the races you are fighting, it might make sense to equip your rifles with an axe. An axe would generate far more force when swinging it than you could generate with a thrust, which may be what you need to kill your enemies. Or it might be you need more stopping power than what a spear-like bayonet could provide - a thrust with a blade is good at killing someone, but its not going to stop them from hitting you in return. An axe swing on the other hand has a lot more stopping power, preventing your opponent from continuing their attack. Also, whilst a weapon axe and a tool axe are significantly different (a tool axe head is far thicker and heavier than one made for combat), you could use your axe bayonet as a tool with some amount of success - a lot more so than what you’d have using a napoleonic bayonet at least. Whilst you’re not going to fell a tree with it, you could definitely cut through underbrush with it like a machete and potentially split wood with it. It may also find some use in cutting down doors or wooden barricades and fences, allowing for troops and horses to pass through easily. I’d see these axe bayonets being used by a specialised division of troops, like an engineers corps, shock troopers or perhaps some kind of support-based unit, rather than the main bulk of the army. An axe is best used when you have room to swing it - eg, not in a tight formation which is better for thrusting from. Also, it’d take significantly more metal to equip all soldiers with axe bayonets than it would with the spear-like bayonets. [Answer] Not axe. Shovel. [![shovel weapon](https://i.stack.imgur.com/nPlHR.jpg)](https://i.stack.imgur.com/nPlHR.jpg) <https://oprishki.wordpress.com/training/thrusts/> A shovel is a useful tool for a soldier, for many reasons. Shovels can also be effective weapons, and even more so if you have time to hone the edge prior to weapon use. Instead of axe bayonettes, have shovel bayonets. I envision the shovel attachment as actually being on the butt not the barrel, because the but and stock are more robust than the barrel and can more easily serve as the supports of a shovel blade. For hand to hand combat, or for digging, the weapon would be reversed. [Answer] I think I have some good answers: Although as far as I know they weren't used by Napoleon's army, rifling may be your answer, and rifles were developed around that time period. Axe-bayonets would have a lot of disadvantages when attached to a musket type firearm, making it heavier, more difficult to aim, and an unwieldy melee weapon. However, assume instead that your civilization develops rifling and incorporates sharpshooters into its military. Rifle mounted axes could be slapped down onto a log or stump, giving your sharpshooter-on-the go a makeshift mounted weapon, and some of the recoil could be absorbed by the log instead of the shooter, possibly allowing for more gunpowder to be used and an increased range of fire. Then, when your enemies charge the sharpshooters, they can still pick up their rifles and either flee or fight. Another option would be to change your battlefield to the ocean instead of land. Axes become more useful when boarding a ship because they can be used not only to cut down enemies at close range, but to cut through ropes to cripple the enemies' ships. And on a ship, your battles will likely be more close-quartered, which limits the usefulness of long-reach weapons like traditional bayonets. Basically, they are either for stabilizing/absorbing recoil, or they are for damaging the enemy's equipment. If your enemies are monsters, then they might not be able to use ships or technology, so that might not help, depends on your monsters. [Answer] The most likely rationale I can come up with is some guy who never actually fought in a battle in his life thought it would look cool. Have you ever tried swinging a woodcutting axe (or a pickaxe, or a mattock, or something similar)? It takes a huge amount of effort to actually use it, requires special application of leverage, and even then is far too slow to be an effective weapon against anything that's realistically agile. On top of that, if swinging for an attack and you miss, it takes far too long to recover from the miss and get to a guard stance, let alone prepare for another swing. The only reason this stuff is viable against zombies in so many movies, TV shows, comics, and other stuff is because zombies are really slow, and tend not to dodge. Real world battle axes were relatively lightweight affairs. They would be used against hide or leather armor, not plate armor, and definitely not stuff like chain mail or scale mail (the whole point of chain mail is to make you hard to cut). That's part of the reason that a lot of historical portrayals of combat show axes used by raiders, brigands, and other people who are most likely attacking unarmored or lightly armored targets. Some long ones were occasionally used by cavalry, but mostly just to gut the other guy's horse or to lop off the unprotected heads of infantry as you ride past them. Now, using one for a bayonet or a hybrid weapon has other issues... The reason that a spear-like bayonet works as well as it does (which is honestly not quite as good as a real spear) is because of how it ends up being used. Because almost all of the force is (usually) applied along the long axis of the gun's barrel, it's very easy to design a reasonably reliable locking mechanism to keep the bayonet attached as you stab someone without damaging the gun in the process (most of the time). A large part of the reason that in real life axe-bayonets (they do exist, see some of the other answers) have been unpopular is because they can't be made this way. Striking with the axe inherently applies force in a way that makes it very easy to damage the gun, or at least severely impact it's accuracy long-term. They're also very heavy compared to spear bayonets (a spear bayonet can just be a long spike, no need for a cutting edge or any extra material to reinforce it heavily or provide a counterbalance), which makes it harder to use the gun as a gun. Something to keep in mind though is that bayonets were never intended to be a 'primary' weapon. Most people who used guns back in the middle ages (and even up until the end of WWII in some cases like the Imperial Japanese Army) carried a sword of some sort as a sidearm, with the being a stop-gap for when they were caught by surprise and couldn't drop their gun and draw their sword. Bayonets suck for actual combat. They're better than nothing, but honestly not by much, especially if you don't have a long (in the conventional sense of the term long) gun to put them on. The only reason they became the standard in late medieval and early modern Europe is logistics. Musketeers with bayonets replaced the roughly 50/50 mix of musketeers and pikemen that was used previously because a bayonet on a long musket works almost as well as a pike, and that way you didn't lose out on firepower just to protect your musketeers from cavalry attacks (and you had one less type of weapon to worry about supplying your soldiers). [Answer] A bayonet is a stabby tool. The reason that Bayonets were so popular in the napoleonic era was that it turned a gun into a spear - and the guns of the era were relatively slow loading. Also smashing at things sideways with an expensive early industrial age barrel would likely damage it.You don't (still) make axes with hollow handles for most part. On the other hand, contemporary guns were heavily wood. Taking inspiration from a [pistol hatchet](https://www.forgottenweapons.com/hatchet-stock-for-a-c96-mauser/) you could possibly integrate the axe head into the stock - taking the idea further, you could build pistols into fully enclosed and reinforced handles - [2 single shots then acting as short hatchets.](https://www.thefirearmblog.com/blog/2010/11/24/axe-guns/) Putting it in the shooty end is dumb - putting it, encased in the butt end makes sense. In addition, rather than open field combat (and if I was fighting monsters, I'd totally go with ranks of riflemen or better yet a volley gun or cannon over an axe), skirmish combat at close quarters would favour axe-like weapons somewhat. Or more precisely, the hatchet gun [Answer] Guns are designed to take force along the barrel (the recoil from firing) not at right angles to it. If you use one like a cricket bat - much beloved of some model soldier designers - it'll a) be hard to swing - the stock isn't designed for that and b) break. The correct way to use a longarm as shock weapon is to turn it around and jab with it - you contact the enemy with the part that would be against the shoulder when firing it. It's a silly idea. ]
[Question] [ Mankind is adrift. Only few millions of people survived, they are struggling to stay alive. Food is hard to find and plants do not grow (mostly). Water cannot be found on surface, the only way to get it is to find an underground river/lake. The world is hot, dry, there are almost no clouds and rain is replaced by dust storms. After years, there are no oceans, only salt deserts. Q: What event/series of events could possibly cause this environment? The cause should: > > * Not kill most of the people - people should starve to death or kill each other for food > * Kill most of the flora > * Make the planet hotter and dry > * Generate no radiation or contamination of food/water > * Be plausible as today. No near-future and no magic. > * BONUS: on areas directly exposed to the sun: burn the skin, causing burns on exposed parts. (This is totally optional) > > > Possible cause: > > My initial thought was some kind of pathogen agent that kills most of the flora, but I really don't know if it would cause earth to become an almost desert world. > > > I also considered a Coronal Mass Ejection, but I don't like the fact that it would kill a lot of people and could contaminate water/food. I'd like a slow apocalypse. > > > Edit: Heat, dust, no water... this is what the outcome should be, not how the process should behave. You could just frezee the entire world if you can explain that, after an Ice age, the earth would be an almost desert world. [Answer] I would go with the pathogen idea. The more plants the pathogen, or pathogens, kill the better but at least the grasses and trees must die. Grasses and trees trap water and soil. Remove these and the next rain washes away any soil preventing food growth. In a drought period grasses store water underground so animals can survive by eating grass. Kill grass and water storage goes. You heard of the dustbowl in 1930s America? That was caused by killing the grasses. By removing grasses and trees you will make much of the Deep South into a desert. In fact, most of the sub-tropical zone will probably become desert. (Climate zones shown on the image below.) Removing trees will also create problems in the tropical and temperate zones. These areas are dominated by forest. In the tropical zone, which is mostly rainforest, the death of the trees will cause all the top soil to wash away. Rainforest soil has practically no nutrients below the top layer so most plant life here will be destroyed. Losing the rainforest will rapidly increase global warming so temperatures will increase a lot giving you your higher global temperatures. Less trees will also reduce river lag times increasing flooding and, since most cities lie on rivers in the temperate zone, a lot of the worlds large cities may have to be abandoned. Even the poplar region won't be safe. Killing trees increases global warming and will melt the sea ice so bad news for polar bears. This will increase sea levels driving people inland and destroying some food growing areas. The apocalypse will kill some people straight away in floods and dust storms but most people will survive the initial consequences and live on, slowly starving to death under the hot sun watching the nutrient poor soil blow away in the scorching winds. At least they will have clean-ish water though. [![Climate zones for reference](https://i.stack.imgur.com/ED3ex.gif)](https://i.stack.imgur.com/ED3ex.gif) [Answer] # By making it cold The colder it gets, the drier it gets. OK so this isn't strictly what you wanted, but the driest periods the planet has experienced were the ice ages. The colder you make it the more of the water ends up locked into the ice caps. Sea levels drop by hundreds of meters, the ice expands down into the temperate regions. It's much easier to remove the water from circulation with cold than heat, Snowball Earth is surprisingly dry. --- # Hotter and drier You can make the land drier by making the planet hotter, however the ultimate outcome of this is to make the sea levels rise rather than fall. You can get to a dust-bowl scenario on land reasonably easily this way. Inland seas and lakes would be lost but you would still get fertile regions in the more temperate zones and on coasts. To get rid of the water on a hot Earth you have to make it go somewhere. This leaves you only with the Sandworm option or similar, i.e. "A wizard did it". --- # Both Go through a phase where it's hot enough to dustbowl the land, then drop the temperatures to ice age and freeze out the oceans. You'll probably kill everyone and everything this way. Internet research says that ice ages can cut in very quickly, but all the sources I've seen are questionable. [Answer] Introduce [sandworms](https://en.wikipedia.org/wiki/Sandworm_(Dune)). Sorry for spoiler tag, but if you haven't read [Dune](https://en.wikipedia.org/wiki/Dune_(novel)) saga, I don't want to spoil it for you. > > Sandworms had a stage in their lifecycle when they acquired water and trapped it in the underground spice melange masses. They were the main reason for sand, for dry [Arrakis](https://en.wikipedia.org/wiki/Arrakis). There was enough water on Arrakis for it to have Earth-like environment. In the [Chapterhouse: Dune](https://en.wikipedia.org/wiki/Chapterhouse:_Dune) the process of drying out a planet is shown with all it's details. > > > If you can introduce a life form that would trap water and not release it, you could dry out the planet surface pretty well. Dry planet would probably appear hotter, too. Or at least have higher temperature variation, with hotter days and colder nights. Plants would die, and thus would no longer stop the ground from being eroded. Oceans would get shallower and more salty. Looks like this will fulfill all your points pretty well. Only... It'd be somehow derivative. --- Of course, it doesn't have to be a literal sandworm. Any organism that hoards water and creates cysts in hard to reach places would do. Especially if it'll render water poisonous, thus preventing roots to suck it back out. Creating such organism might be possible. At least I don't see it less feasible than pathogen able to kill all flora but leaving fauna intact. [Answer] I would go with "[electric wind](https://www.nasa.gov/feature/goddard/2016/electric-wind-can-strip-earth-like-planets-of-oceans-atmospheres)", which is what's currently being cited as the cause of Venus's desiccation. In essence, strongly charged electrical wind in the upper atmosphere performed an electrolytic separation of atmospheric water, and drove the ionized oxygen and hydrogen off into space. On Earth, you could imagine this process interrupting the hydrological cycle, preventing or drastically curtailing rainfall. It's not realistic to truly desiccate a planet on non-geological time scales, but if you prevent rain from falling, you'd effectively kill off any land-based plant life. If you wanted, you could say it was kicked off by a [massive solar storm (CME) hitting Earth and charging the atmosphere](https://en.wikipedia.org/wiki/Coronal_mass_ejection#Impact_on_Earth), which you could also use for your bonus objective of burning those in direct sunlight - this one had enough UV radiation to decimate the ozone layer, and the electric wind phenomenon that it started keeps new ozone from forming in the upper atmosphere, so now people get sunburns and eventually develop skin cancers from prolonged epxosure to direct sunlight. CMEs are not actually deadly to people as you seem to think, based on the comment in your question, [and we have historical records of being hit by some pretty big ones, most notably in 1859](https://en.wikipedia.org/wiki/Solar_storm_of_1859). People did fine, electrical equipment, however, did not. [Answer] What you are describing will actually happen to Earth, but your characters will need to be incredibly patient, since this is projected to happen about [one billion](http://www.spaceref.com/news/viewpr.html?pid=908) years in the future. As the Sun burns through it's hydrogen fuel, more and more "helium ash" accumulates in the core. The helium will not fuse under present conditions, so the radiative pressure from the core gradually decreases while the gravitational pressure remains constant. The sun's core is squeezed with increasing pressure and the rate of fusion also increases at a slow but steady amount, increasing the radiative output of the Sun (to maintain equilibrium). The Sun is thought to have increased in brightness by up to 30% since the birth of the Solar System. The ever increasing heat energy reaching the Earth increases evaporation, and gradually the atmosphere becomes saturated with moisture. By 1,000,000,000 AD, the Stratosphere is saturated with moisture, and then an irreversible chain reaction takes place. High energy ultraviolet radiation striking the atmosphere starts striking the water molecules at high altitude, breaking the water apart into hydrogen and oxygen. Hydrogen is such a light gas that the extra energy imparted by the breaking of water molecules will allow it to achieve escape velocity, and leave the Earth's atmosphere for good. Since the heat output of the sun is continually filing the atmosphere with water vapour, this process will continue unimpeded, while the hydrosphere gradually evaporates. This process includes other strange effects, such as CO2 leaving the atmosphere in @ 500 million years as the carbon cycle is interrupted and plant life becoming extinct, but even then, we are looking so far in the future that post humans will have evolved into post-post humans, and perhaps have developed some sort of mega engineering like [Star Lifting](https://www.youtube.com/watch?v=pzuHxL5FD5U) or moving planets around to deal with issues like this. Since I can assume you want this to happen now, rather than 500 MY from now, you will need to find a way to accelerate the Suns stellar evolution or artificially increase the Sun's output. Since the rate of fusion inside a star is moderated by the mass of the star (larger stars have more mass and are therefore hotter), you either need to dump trillions of tons of mass into the star (more than the current mass of the Solar System), or do something like dropping a neutron star or mini black hole into the Sun's core to "pull" more mass into the core. How this happens is an exercise for the reader. [Answer] Out of the box answer: Alien invasion About a hundred years ago tens of thousands of Monoliths descended. They can't be scratched or dented, they appear to be smooth black oblongs with dimensions that scale according to the [cosmic 4 sequence](https://www.quora.com/Why-is-4-considered-a-cosmic-number). After a while scientists realised that the Monoliths had a peculiar property: They seemed to attract atmospheric H20 and, through functions unknown, capture it. Once some unknown criteria is met the Monoliths rise and depart our planet and new ones descend. A constant stream of Monoliths are now entering and leaving Earth's atmosphere, each stealing some precious water as they go. Nobody is sure why the Monoliths were sent, but the effect is undeniable: Slowly but surely all the water on Earth is being removed. If the space above the monolith is covered for any reason the monolith will slowly and inexorably rise, pushing all before it, and a replacement monolith descends elsewhere. As the sun continues to make water evaporate and the Monoliths continue to capture it humanity is becoming more desperate, enclosing the last water stores in closed-systems deep beneath the earth. Plants can be grown in hermetically sealed domes, but as the global average humidity continues to drop all but the most hardy plant and animal life is beginning to die off, and the Monoliths have started to land in increasing numbers nearer and nearer to the domes. We don't know why this started, or if it will stop, but we do know that this thirst will kill us. [Answer] Within a few year (decades or centuries) it is virtually impossible due to the really HUGE amount of water stored in the oceans. Human activity can do the trick: Imagine a hydrogen based economy (with hydrogen powered cars, ships, planes etc.) on a really big scale that looses permanently some hydrogen to the atmosphere and finally to interplanetary space. This can do it, but we need to consume much more energy than we do today ... and humans will notice the falling sea level hopefully soon enough to change their economy! [Answer] Without worrying too much about physical mechanics: * You could postulate a world where [some massive mantle-cracking geological trauma] has caused rifts in the earth's plates, and other fissuring — which has allow the oceans and groundwater to largely 'drain' into the layers of the earth. A few advantages to this mostly-imaginary physics: 1. It could happen fast: Quirk of the earth's core rotation. A celestial event. Etc. 2. Draining/absorbing of the oceans would take a while, and allow the slow-death / adaptation you mention. 3. It would enable you to have a wealth of 'new world' events that players wouldn't presume: * All the water in the mantle has to change, eventually. There's too much heat for it to remain there forever. * random deep-earth catchments could be discovered. Empires built on access to secret caches * Geysers of mythological proportions could occur suddenly. The watery equivalent of volcanos. * New forms of earthquakes would occur. These tremors could be more electrical / geo-magnetic, since the earth has more layers of water in it now (which is a dielectric, like an electrical battery). + so, think earthquakes that cause electrical storms; change animal migration patterns; cause earth-light phenomenon; blackouts and other cognitive / perceptual changes in people & animals * the now dry lakes, seas, and oceans are likely candidates for deep-earth movements of water, which cause huge sinkholes of sand, perhaps so expansive that they are like sand-rivers. * all of it can culminate in a world-breaking rebirth event, where the waters return to the surface. Can be as epic (sudden in time) or long & drawn-out as needed. Seems like fun times full of mythological heights. [Answer] It is going to happen in Earth in about a billion years: [Runaway greenhouse effect](https://en.wikipedia.org/wiki/Runaway_greenhouse_effect). Increased Sun activity will cause more water to evaporate until greenhouse effect caused by water vapor will increase temperature to a point where oceans will boil. The problem with this scenario is that it will get too hot for your purpose - several hundreds of degrees - and humans won't be able to live like in a desert. It will be more like an oven or a furnace than a desert. And if you don't want to wait a billion years, you can trigger runaway greenhouse effect by building up huge amounts of greenhouse gases in the atmosphere to raise temperatures a few tens of degrees and water vapor will complete the work. [Answer] ## The thing standing between the Earth as we know it and your apocalyptic wasteland is the Earth's magnetic field. The Earth contains a spinning nickel core that interacts electromagnetically, this redirects charged particles and hinders radiation. Were you to weaken this process somehow, possibly by stopping the Earth's rotation, you could cause the field to weaken. When a planet has a weak magnetic field it is no longer shielded against the electromagnetic radiation put off by stars near it. Take for instance, Mercury. Mercury has very little atmosphere in part because it lacks a magnetic field, this means the solar radiation is intense enough to strip off any gas or water vapor as well as heat the surface enough to boil liquids. The potential scenario could be that the Earth ceases to spin, at once or over time, (so 1 day = 1 year). In this scenario the Earth's oceans and atmosphere would gradually be stripped away by radiation leaving behind a half radioactive oven, half sunless icebox with little or no breathable atmosphere. The other potential scenario involves not eliminating Earth's protection, but rather increasing the strength of the radiation and charged particles it repels. If the Sun became more powerful, which it eventually will, a similar process would occur. You can choose how advanced this process would be, you'll have to choose a time during which the atmosphere and some surface water still exists to some extent, and radiation and lack of atmosphere is intense enough to kill without protective clothing and provisions but not enough to be completely uninhabitable (like the surface of Mercury) without lots of expensive equipment. You could also offset the Earth's orbit. If you skewed it a bit, it could get closer to the Sun, but only temporarily. This would not be drastic enough realistically, but it is a powerful climate change mechanism. Regular oscillation in the Earth's orbit is the principal cause of ice ages. Moving the Earth closer to the sun is a plausible idea though. [Answer] Collapse the planetary magnetic field. Collapsing the magnetic field also ends the magnetosphere / Van Allen belts. Those protect the upper atmosphere from erosion. Over time, the atmosphere will lose pressure. Liquid water will evaporate and this will have a short term compensating effect, but eventually you will be left with a very thin atmosphere and no water. For an actual example of this process, see Mars. [Answer] [Giant Space Tree!](https://en.wikipedia.org/wiki/Rainbow_Mars) In this novella Niven posits > > a spacefaring lifeform which shoots seeds across interstellar voids sucking up all of the water on a planet before launching new seeds out and perpetuating its lifecycle. One has already gotten Mars, and Earth is next. > > > Niven's take on the concept is rather absurdist. That whole collection of short stories has a humorous bent to it. The central idea of that particular short story is pretty intriguing though, and a serious take on it might yield interesting results. [Answer] The most plausible cause for all of that to happen is Earth gets closer to the Sun. Only 1 inch closer will be enough. You could make a scenario where some object(asteroid) hits the Earth and Earth gets closer to the Sun. All the things mentioned above would happen as a consequence of this event. [Answer] Ozone strippers, dump enough CFCs into the upper atmosphere and the UV that punches through will kill most of the life on Earth, the added UV will also destroy water molecules reasonably rapidly, the hydrogen escapes the atmosphere and the oxygen decomposes the dead Carbon and Nitrogen from the land causing runaway warming as nitrous and carbon oxides build up, the end result looks a lot like Venus as eventually the oxygen runs out of carbon and starts to oxidise sulfur from the land surface and the gas pressure just goes up and up. ]
[Question] [ I am writing about my own fictional cluster of solar systems where one planet had many environmental circumstances that lead to the majority of the planets species evolving to be blind and rely on sound and echolocation. On this planet one intelligent species eventually formed a civilization and I have been building how their society might work and their cultures but I have hit a bit of a wall. I want this species to become spacefaring but I have no idea how they might be able to do so. How would a blind species that can only hear and feel interpreted space and stars? How would they be able to navigate in space at all if they cannot see any type of light? My question is: How would a blind intelligent alien species ships be made? Assume that they are on an earth like planet so they will have similar take off restriction as us. How might their ship interface be like? [Answer] If every species on Earth were blind, they could still sense temperature changes between day and night, the timing would be too coincidental to be random, they would still sense rain, winter, summer, and those cycles. They would develop theories, religious at first but increasingly scientific: You can block the sun and rain with shade. Not just by finding it, but by creating it, or carrying the shade maker with you -- a parasol. Obviously, the sun is a special kind of radiation, with sharp "shadow" boundaries, and is unaffected by wind, like rain. Eventually they would figure out it is radiation, and could develop means of detecting it and other radiation. Whether their equipment is haptic (by touch or position) or audio, they would find stars, moons, perhaps planets. It wouldn't be easy, but they could. And the idea that light occurs in frequencies, just like sound, would be their obvious analogy. Just like we humans have developed means of perceiving and generating both light and sound beyond our perceptive abilities: ultrasound, infrasound, infrared, and ultraviolet, X-rays are form of light. We even use the same exact math for sound waves and light waves; at least up until special relativity kicks in. And there is no reason to think their math isn't up to the task. And most of our understanding in cosmology has nothing to do with the perceptible light of stars -- We use instruments for light well beyond our senses to understand stars. Even the James Webb telescope and it's stunning images is an infrared telescope, the "photographs" we see are translations into our visual range of radiation at frequencies well below our visual range. Don't rule out the intelligence of your aliens; they'll figure it out. Just realizing there is a Sun would be a major revelation, on a blind planet, but still, I think, an inevitable conclusion. Edit: P.S. Look at the Starship Enterprise. They seldom "look out the window", they rely almost entirely on their viewscreen. A blind race would similarly rely on touch screens and synthetic sonar audio (like dolphins and bats use sonar to "see" in the dark) representations of what their external "cameras" and sensors show. They'd have no problem navigating. Yes, there is no sound in space, but they can translate light into synthetic sound, just like we translate the infrared pictures of the James Web telescope into frequencies within our own limited range of vision. [Answer] Imagine an alien pilot in the middle of a spherical chamber. The chamber is covered by millions of tiny speakers. Some of those speakers - perhaps a thousand - emit sounds. Each of those speakers represents a star in that direction. Its volume, frequency and timbre represent various properties of the star like distance, mass and spectral class. A language encoded in melodic overtones of each sound encodes the name of the star. A human in that chamber would only hear a terrible cacophony of noise. But not so the alien with its superior hearing ability and its brain specifically evolved for making sense of it. It can isolate every single source of sound at once, and its mind can turn them all into a clear 3d representation of its interstellar surrounding. When the alien hums the name of a star, speakers from all direction blurt soundwaves at the alien. A human in the chamber would think that something on the ship just exploded. But what they actually heard was an explosion of knowledge. In less than a second, the alien just learned everything the ship's database knows about that star system. What planets and moons it has, the history of its exploration and the current economical and political situation in it. "But is that really possible for a lifeform to evolve like this?" ... thinks the lifeform whose retina currently absorbs the light waves emitted by a rectangle of millions of tiny red, green and blue lights, forming patterns its neural network interprets as "letters", which form "words", which forming "sentences" representing abstract ideas which it visualizes. [Answer] There is sensing, and then there is imaging. I think the concept of being 'blind' is locked in to imaging things with a lens onto a surface like a retina and or a piece of film that preserves the spatial relationship of what is being imaged - maybe not perfectly in the case of an astigmatism or other aberrations but basically maps things in 1 to 1 way. If we have two such sensors separated we can get some idea of depth perception and an idea of how far away something is. Or if a person has only one eye, perhaps from experience has an intuition of how far away something is from previous experience. However to form an "image" you don't need to have a lens, or have the photosensors all located in a nice 2D array like a retina, or CCD or CMOS camera. if do something clever you can reconstruct and image with pretty much much any kind of sensor, usually by chopping signal spatially, or understanding the field of view of the sensor and moving the sensor around, then doing some kind of mathematics to reconstruct the signal. The mathematics in animals being analogous to having some type of brain processing the image biologically. Early televisions for example sometimes only had one sensor and used a spinning disk. If we look at the signals from other animals with some kind of 'eye' like a compound eye like a human and fly looking at the same object, it could be a pretty different representation from our human perspective. The human seeing one image, the fly a lot but both using a brain to utilize the information input. Or perhaps consider a scallop that has a lot of "eyes" essentially photoreceptors along the edge of the shell. So the 'image' for different animals could look quite quite a bit different. Frogs for example have their retina wired in way where the edges of objects are highlighted which is good to tracking a moving object. The pupils of carnivores and herbivores are usually oriented in different ways. Driven by the evolutionary needs of hunter vs prey. Some need high resolution like a hawk, other animals maybe a general indication of where light of motion is coming from. But I think you can take a few cues from how earth plants sense, and then extrapolate how they might "see" the world in a way that is useful for them. The biggest differences being probably the speed of processing the image, and how fast the plants move. Plants on earth - actually have pretty sophisticated sensing. The orient to the sun, and they have different types of chlorophylls, or absorption mechanisms. - blue light helps tell them where to orient their leaves. The ratio of blue to red light helps let them know how closely other plants are growing near them since the reflected light from surrounding leaves is a different color than non reflected sunlight. They also have circadian rhythms. They can sense gravity - useful as buried seed to orient which way to grow the shoot up out of the soil, and the roots down. Plants sense chemicals and may even communicate with each other chemically. Or at least respond to a damaged plant nearby. They can have a tactile sensor - like the hairs on venus fly trap sensing bending or vibration, or perhaps when a vine grows in a helix up a pole. A lot of these senses are focused on the immediate environment of the plant, so what would drive the plant to want to be able to sense things farther away? What pressure would drive the plants to respond faster to stimuli? But the idea of plants seeing has been around since Charles Darwin's son, and in the past 5-10 years it seems like the idea is making a comeback - but perhaps they just don't image like an eye with a lens. From this [Scientific American](https://www.scientificamerican.com/article/veggies-with-vision-do-plants-see-the-world-around-them/) blurb, you might be able to get some ideas. > > Recent work also shows that some plants, such as the cabbage and mustard relative Arabidopsis, make proteins that are involved in the development and functioning of eyespots—the ultrabasic eyes found in some single-celled organisms such as green algae. These proteins specifically show up in structures called plastoglobuli, which are famed for giving autumn leaves their red and orange hues. “This discovery suggests that plastoglobuli in plants may act as eyespots,” Baluška says. > > > > > Other observational research reveals plants have visual capabilities we just do not understand yet. For instance, as reported in 2014 in Current Biology, the climbing wood vine Boquila trifoliolata can modify its leaves to mimic the colors and shapes of its host plant. > > > [Answer] They probably wouldn't. The way you're describing blind seems as if they have no sense of any spectrum of light at all, which would mean they also wouldn't sense infrared and wouldn't be able to tell thermal differences. Although we may say that's our sense of touch, heat is still carried by light. Even basic vehicles would likely never be invented on such a world; a bicycle is a simple vehicle but even that would pose significant problems. A small unexpected change in terrain could easily dismount a rider, and the faster one moves that becomes more likely to happen as well as more difficult to detect with echolocation. If you want them to invent something like a car then they would likely need to reach the computer age first so they could make machines that are capable of radar telemetry, which would make them having their industrial revolution much more difficult. A train would be somewhat easier to make for them since it would rely on a track and wouldn't require echolocation. But if they're doing that then you have to take into account that they make a lot of noise and that would disrupt their primary sense, so they would likely not even use internal combustion since it's quite loud. Even machines we use which are quiet by comparison could be loud enough to disorient a species which evolved sound as their primary sense; like how you can flip on some devices and hear a high pitched ring like tinnitus, or hear the thrum of a motor as it spins. All computers use a crystal to determine their clock speed, this species wouldn't even be able to easily use piezoelectric devices because as that crystal vibrates it also creates sound due to that vibration. If, by some miracle, they invented vehicles and propulsion systems for them that were silent or soundproofed they could hypothetically reach the space age. But their space age would probably use something like a space elevator rather than a rocket since it wouldn't be as loud (side note: space elevators also don't need to achieve escape velocity since they're not ballistic at all). After overcoming all of those nearly impossible obstacles it's easy enough to figure out how to navigate though. They would have to have devices that sense light at that point, so they could just point something like a radio telescope around until they found something interesting. NASA has released sound clips of what the different planets sound like by converting their EM signatures into audio, there's no reason they couldn't do something similar with a spectrograph since, as another person pointed out, sound and light waves are largely the same mathematically. Except with their version it would probably play the inverse of what we would see, with the tones generated representing the black lines on a spectrogram rather than us seeing a rainbow with some spots missing. They could use infrared to determine how hot an object was so they didn't fly into a sun, and then determine if any planet had the same or similar EM and spectrographic sounds as their own for determining habitability. In order to determine distance they could use the doppler effect, which they would know of since it exists in both light and sound. Determining the size/ mass of a celestial body would probably be difficult though, but you would need that for understanding another planets gravity and atmosphere so that one could safely land a craft, even a probe. I imagine if you were sitting in a craft designed to be piloted by sound you would probably hear something like old-school 56k modem noises instead of seeing displays anywhere. Modems take sine waves, chop them up, and reshape them in order to convey information. The term modem is actually a portmanteau of modulate and demodulate, describing the process these sound waves are converted into information. Using a process similar to that, they could effectively understand their sensor readings just efficiently as a human could by reading it on a panel; perhaps even having multiple audio streams playing at once in different frequencies and they simply choose what to listen to like you might listen to a specific person in a crowded room or read from a specific point on the display. So far as how do they discover space exists, that one seems obvious to me too (if there's sunlight on that planet). Aurora Borealis actually creates an audible sound as the suns radiation interacts with the earths magnetic field and creates a vibration. This phenomenon is something that was largely dismissed as local 'old wives tales' up until relatively recently when it was recorded and sparked study into it. But for a species that relies on sound rather than light, they would probably notice it much much earlier and might even have a religion based around it. After all, they're hearing the sun and effectively the giver of life for their planet so it's plausible it could be interpreted as the voice of god by a primitive civilization. Edit: Didn't think I had to explain this, but I seem to be mistaken. Every living thing in our biosphere emits some spectrum of light and cannot survive without it. You can measure the EM field of a person, and the electromagnetic spectrum IS light, meaning we emit light. Birds sense EM fields and navigate using that; pit vipers have sacks within their heads which allow them to effectively have "heat vision"; plants tend to grow in the direction where sunlight is coming from. You could remove the eyes of a rattlesnake or pigeon and it would still have some sense of different light spectrums. OP specifically states that this is a world where evolution took a different path and seems to imply (at least to me) no photosensitivity of any kind. [Answer] We do actual spacecraft ops almost blind. Even star trackers don't generally record pictures, just the coordinates of a few reference stars. Accelerometers, gyroscopes, magnetometers, Sun and Earth sensors, radio ranging, and Doppler measurements are not visual. And humans are almost blind anyway. We can only see a tiny part of the electromagnetic spectrum. One project I've recently been involved in is [SEXTANT](https://en.wikipedia.org/wiki/Pulsar-based_navigation#Experiments), a demonstration of space navigation using x-ray pulsars. [Answer] If they are blind, mayhap they developed as a subterranean species. Hence could have some advantages over humans in traveling in confined spaces like spaceships. Although disadvantages besides the obvious, like severe agoraphobia. Which would impede the discovery of space flight. Though that said, and underground existence is harsh and would breed hearty minds for survival. There would be those that viewed the void above and accepted it's challenge. One would surmise without eyes heat reception would be a secondary sense that would be developed. Touch or otherwise, infrared radiation would be the gateway into the electromagnetic spectrum where they would be able to start detecting objects in the void. Jumping from IR to Radio they would have be able to detect other celestial bodies in the beginning. [Answer] The sense of hearing does not have to be the only way. In the same way that [magnetotactic bacteria](https://newatlas.com/biology/bacteria-magnetic-field-sense-hypothesis-magnetotactic/) or other species can utilize molecules that respond to the Earth's magnetic field, it can be possible for your alien to discover some chemical or molecule that's extremely sensitive to the [curvature of space and time](https://en.wikipedia.org/wiki/Spacetime). This would enable it to be aware of masses that wiggle or move in space. The ripples caused by such masses (stars, black holes, planets, asteroids or even other entities that humans have never discovered because we don't have the sensory capabilities), can be detected by your alien's extremely sensitive cells, which don't have to be like our cells. They can be of a sub-atomic nature or even much more massive than the earth...which means your alien could be a giant that's as big as our solar system. Their ships can either be covered with sensors that detect the ripples or the ships could even be composed of multiple aliens, like how [these slime molds assemble](https://www.youtube.com/watch?v=bkVhLJLG7ug). Their take-off restrictions don't have to be like ours. They can simply get into a much larger creature and [mind control it](https://www.nationalgeographic.com/animals/article/141031-zombies-parasites-animals-science-halloween). So if your alien is like an ant that's too small to break out of the surface tension of water (gravity of planet), it can get into the body of a frog and control it to get out of the water. As an example. Even intelligence can be [thought of differently](https://www.techrxiv.org/articles/preprint/Facts_and_Anomalies_to_Keep_in_Perspective_When_Designing_an_Artificial_Intelligence/12299945). [Answer] # Translate sensors for the blind The problem is approached as a person who can see vs a blind person. That creates a wrong image. From a sharks perspective we would be blind, yet we can navigate under water. We even have large submarines going at respectable speeds at depths where vision is moot. We translate what sensors we have to something we understand. If you have a spacefaring civilization you can be certain they have researched into translation. Much like we translate spoken words to vision (written words) or touch (braille), they would translate a multitude of sensors into something understandable. We do it all the time in the real world. Plenty of deep space pictures are made with the electromagnetic spectrum we can't see. If you think that space still is beyond the imagination of a blind person, even with translation, I would say it is beyond the imagination of normal humans as well. Space is unbelievably big with unbelievably big and powerful objects and events. This is spaced out by unbelievable distances of empty space. We just make it understandable by simplifying it and some math or results. A blind person would do no other thing. They would translate their location into simple terms they understand thanks to technology, supported by astrophysics math. They then make decisions that are performed by computers. [Answer] We know a lot about space that we cannot see - such as the surface under the clouds of Venus. We invented radar, and translate the radar results to a visible image on a screen. So we see what is not visible. Sound move in the same way as light (although the longer wavelength yields lower resolution.) So these aliens "see", but not by utilizing light. Echo location gives them a mental image of their surroundings, with a resolution limited by wavelength. Such intelligent aliens surely invented equipment for improving their seeing. Amplifiers lets them "see" a bit further. Their telescopes. Using ultrasound might allow zooming in on smaller details. Their microscopes. They would notice that the atmosphere ends, limiting what they can "see". But their scientists might discover radar just like we did. And instead of visualizing with a screen, they would visualize by converting the signals to sound. A spaceship might use radar for seeing planets, "visualizing" by running the signal through a system of speakers. With several small speakers, they can synthesize phase and direction matching what the ship radar "sees". Optical instruments can detect stars too far away for radar, and "visualize" in a similar manner. So, eyeless aliens can navigate space just fine. They might evolve eyeless if their atmosphere isn't transparent to light. [Answer] When you say blind, do you mean blind to only the wavelengths of photon energy that human eyes are sensitive to? Or are they blind to the entire electromagnetic spectrum. -- Because if they only could rely on sound/echo location... I think space navigation is out of the question for them. They would need some kind of way to detect energy waves-- something from gamma down to x-rays or visible light to humans, or all the way low frequency like 'radio' waves. We make HUGE radio wave telescopes here on ear h to peer way way way back to the early universe letting us literally look back in time and 'see' what was happening billions of years ago. Interesting question. But if they truly were limited to sound, i think the entire 'intelligence' part may come into question since they surely would be able to use other energy waves and build devices to convert that into something they could then 'hear'? -- odd idea, what a unique world that would be i can only imagine. [Answer] As a 'frame challenge', this question seems to me to fall into the category of 'What is the sound of one hand clapping?". No matter how much thought, concentration, or focus is put into the answer, the answer just does not take any substance. The question is very premature. Without understanding how this society preserves and communicates abstract ideas, learning, and scientific illustration, it is impossible to give any notion of how they would design an interface between the complex operation of a spaceship and the operator. How does this society preserve a representation of reality in their mind? A species that has always been blind, and that has never had any contact with any species that HAS sight or visual experience, or that has never had any evolutionary experience with visualization, would also have no printed form of communication, no drawings, no concept of perspective, no system of scientific or mathematical representation or symbolism in any form that even approaches our complexity. Most attempts at an answer would, I suspect, fall in to the category of '[anthropomorphism](https://www.wordnik.com/words/anthropomorphism)' - > > noun The conception of animals, plants, or nature in general, by > analogy with man: commonly implying an unscientific use of such > analogy. > > > But the category of 'animals, plants, or nature' also includes 'alien sentient species'. Most answers involve a translation or projection of our 'seeing' or 'visualizing' world into the world of the blind, allowing the blind to make 'adaptations' to understand or interpret our visualized 'seeing' construction of reality. But in this civilization there would be no 'seeing world' to translate. They would not, could not, even in the remotest sense, have any concept of the world as we understand it. None of the visual constructs that we use to represent our world would even be contemplatable by them. Their minds would be totally different, their symbolism for thinking and abstract reasoning totally alien. There would be no ability to 'visualize' anything. Their minds would be totally different from ours, and operate in a totally different manner, with totally different structures. There would be no evolutionary similarity between the minds of this species and our mind. Nothing in the history of evolution of this species has any instance of 'visual perception', that would necessitate any brain area or structure that would lead to any form of the mind being able to 'visualize' the world. The entire concept of 'visualization' and 'visual recreation of reality' would be non-existent in the mind. And there would be no mind structures that evolved to even simulate it. For instance, without sight, there is no mathematical symbolism. No representation of numbers, equations, mathematical concepts such as the 'integral' sign. Trying to envision how this society would operate in any engineering/scientific manner is pure conjecture, it is so beyond anything humans can even conceive of. Even such a concept as a 'straight line' as we form it would be, in a non-visual species, not even remotely close to how we 'visualize' it. In fact, it would not even be 'visualized' in this species. The visual area of our mind has cells specifically purposed to detect and record instances of 'straight lines' in the visual field and incorporate them into the general zeitgeist of our thoughts and perceptions. When we see a straight line in the visual field, these cells are triggered and pass the event up the chain of processing. These cells are primitive and pre-historic, pre-human in fact. They are so ingrained and integrated in our information processing and thinking, at such a basic low-level neurological level, they form the basis of our interpretation and understanding of our written language and of mathematics. Any species that has never had, in their evolution, any experience with visualizing straight lines would not have these structures, these cells, and this concept. Yes, it is true we can impart in the non-seeing person our neurotypical concept of a 'straight line', but that is only because as a visual species we HAVE developed this concept of a 'straight line', even in the blind. If there were never a way to visualize a straight line in the first place to this species, there could be no method by which this visualization could be imparted to the non-seeing. That is, we can communicate to the non-seeing the concept of a straight line ONLY because, as a visual species, we have formed the concept, and we have formed the mind structures to handle such a concept. Even the blind are born with the brain structures to encompass the concept. This species could not incorporate or integrate the 'straight line' experience and concept into their thinking the way we do. Before any answer to 'how could this species interface with a spaceship' can be answered, therefore, one would have to know exactly how this species represents reality in their mind. Otherwise, any answer is just conjecture - projecting how we, as a seeing visual species, perceive and think about the world, onto this species whose brain structure, thinking, conceptualization, and symbolic representation would be completely unrelated to anything human. ]
[Question] [ In my world magic is conferred genetically. Their are five "types" of magic, which never mix. You either have one type, or you have another (or none at all, the sixth option), you never have a mix of two. In real life we see this behavior frequently with two discrete options. By that I mean two distinct options, either one or the other, not a mix or a gradation. For example, we have the green or yellow pods of the famous Mendalian peas. They are either green or yellow, and don't mix between the two. However, for most traits with a lot of options, we have a gradation, like skin color or height, and not discrete phenotypes. What would the genetics look like for six phenotypes rather than two? Assume that inheritance works exactly like it does for humans on Earth. No magic is involved in reproduction or inheritance. For this reason, this question is science-based. [Answer] All of the answers so far either do some hand-waving with DNA bases or amino acid codes, or try to construct six discrete phenotypes from a mixture of different alleles. I'd like to offer / describe a biologically possible solution, that is at the same time very 'basic': You can have five different variants of a genes (or six with one being magically 'inactive'), one for each type of magic, but still have only one active in each person. The biological trick for this is called [allelic exclusion](https://en.wikipedia.org/wiki/Allelic_exclusion). In humans the body uses it to suppress one of the two X-chromosomes in females (they only need one) and - more to the point - to prevent certain specific genes from being expressed from two alleles. (This is important in the immune system, where any given B-cell should only produce exactly one version of the B-cell receptor/antibody). In your case you would have six different possible alleles. While each person will have two different ones in their genome, only one will be active in each person. This also means that children can inherit a magic type (including 'no magic') that their parents are not actively showing, as long as they carry the genes for it. Edit, a few more things: * This system works both with the 6 gene variant (-> no magic has a gene) and with the 5 variant (-> no magic is simply the absence of any gene). The latter version will mean that magic is always dominant over 'no-magic', because persons with only one gene, will obviously express it. * The silencing of gene normally has to happen in the 1-cell embryo stage, otherwise you can get people with one half of their cells 'fire' magic and the other half 'water' ([spotted colouring](https://en.wikipedia.org/wiki/X-inactivation) of cats works that way). Of course, if you wanted to, some freak of nature like this could still exist with two different half powers * If anyone ever asks for an evolutionary reason to have allelic exclusion on the magic gene: maybe having two competing kinds of magic in a single cell just mean bad things for that organism. [Answer] Blood type, there are six alleles for blood type with four phenotypes. Just use a similar plan and make them all co-dominant instead the normal setup (O does code for a protein it just doesn't work). So now you have six genotypes and 6 phenotypes. basically take this chart and ignore the blood type column. so A+O would be its own thing and not the same as A+A. [![enter image description here](https://i.stack.imgur.com/RemF6.png)](https://i.stack.imgur.com/RemF6.png) this also gives you a frequency you can map. So some types will be more common than others. If those genes are not the end result but instead code for the activation protein for different pathways, then cofactors don't even have to be related to each other. AA = type 1 AB = BA = type 2 BB = type 3 AO = OA = type 4 BO = OB = type 5 OO = type 6 Of course you could have the super rare [chimera](https://en.wikipedia.org/wiki/Chimera_(genetics)) individual who expresses all three and thus is something else, because they are not actually one person biologically. Biological chimera are extremely rare and are a product of zygote fusion. These may occur no matter how you decide to establish the genetics. You can also just ignore these individuals and say they self destruct in the womb. [Answer] You are in luck! Six variations fits quite nicely into the genetic code; look here at the [DNA to Protein](https://en.wikipedia.org/wiki/DNA_codon_table) Table. There are four DNA 'letters', ATCG. It takes 3 letters to specify a code for one of our amino acids; or one of the control codes ('Start', 'Stop'). That is 22 results for 64 possible combinations ($4^3$) so 42 of the 64 codes must duplicate some result. The 'winner' for this is Leucine, which has SIX distinct genetic codes: TTA, TTG, CTA, CTT, CTC, CTG. Proteins are a link of such amino acids that fold into some specific sequence. IRL of course, Leucine is Leucine is Leucine; the ribosome translates all six of these things into the same amino acid. However, for fictional magic purposes, the construction of your magical organ must depend upon DNA, and you make which type of magic a person can do depend upon seeing the correct variant of Leucine in one or more places within this organ. If you want the magic to be fairly common; this could be in one place. If you want it to be more rare, demand it in multiple places: Say the chances of one variant appearing is 1/6, then getting the same variant in two places is 1/36, getting the same variant in 3 places is 1/216, etc. People with a mixture have no magic. This is likely how you would ensure heritable magic (or none at all), the chances of 2 nucleotides mutating exactly the same way in an offspring are very remote. However, you could have SNP (single nucleotide polymorphism) mutations (just one nucleotide changed) with a very low % chance that make the offspring of two same-magic parents have mixed leucine types and thus no magic at all. [Answer] There are plenty of ways of doing that, you should presumably choose one that fits your story the best. 1) A person can have active mage gene from A-F or 0 (not working). A person is a mage when has two the same copies like AA or CC. Any other combination is simply not functional. Means that a mage should marry someone of his genetic group, which may create interesting inbreeding. 2) A magic is passed in genes that don't follow Mendelian rules - either in Y chromosome or mitochondria. Wizardy is being spread only in male/female line. 3) You may just pick some combination of dominant/recessive genes, where someone technically has some gene, but there is no continuum. [Answer] One locus with three alleles are enough to make six phenontypes. Let's suppose that magic ability is linked to a [locus](https://en.wikipedia.org/wiki/Locus_(genetics)) M for which there are three [alleles](https://en.wikipedia.org/wiki/Allele), M₀ (null magic, "muggle"), M₁ (standard magic) and M₂ (super magic); furthermore, M₀ is partially [dominant](https://en.wikipedia.org/wiki/Dominance_(genetics)) over M₁ and M₂, and M₁ is partially dominant over M₂. Now you have the following genotypes and phenotypes: 1. M₀M₀ - completely non-magical, a pure muggle. 2. M₀M₁ - weak magical of the first kind; M₀ is partially dominant over M₁, with the effect that the carrier has a little magic, but less than an M₁M₁. 3. M₀M₂ - weak magical of the second kind; M₀ is partially dominant over M₂, with the effect that the carrier has a little magic, but less than an M₂M₂. 4. M₁M₁ - standard magical ability. 5. M₁M₂ - increased magical ability; M₁ is partially dominant over M₂, so that the carrier has more magical ability than M₁M₁ but less than M₂M₂. 6. M₂M₂ - super-magical; the carrier has highest magical ability. [Answer] DNA is fundamentally a discrete structure (a finite sequence built from a finite alphabet), so at a genetic level, all traits are discrete. However, there may be so many genes involved that there are many, many possible phenotypes, making the trait appear continuous. Also environmental factors like nutrition and sun exposure may play a role in traits such as height and skin color. But at the enzymatic level, all traits are discrete, and since inherent magic probably falls outside the realm of environmental effects, I'm going to assume that having a particularly magic type has a direct correspondence to enzyme activity. The tricky part is coming up with a set of enzymes and enzyme variants with exactly 6 phenotypes. The biggest obstacle to overcome is avoiding the effect of codominance. Perhaps the most obvious solution is to have a single gene with 6 alleles--but remember that humans are diploid and thus, everyone has two copies of every gene. Since every allele corresponds directly a magic type, and every person has two alleles, we wind up with 21 total phenotypes. We can get around this in a couple of ways. We could put the gene on the X chromosome. Males have only one copy and females only express one copy. But this has the effect that males always inherit their magic type from their mother, while females could wind up with either their mother's or their father's type with about equal likelihood. Alternatively, we could reduce the number of alleles to 3, which would result in 6 phenotypes. Each magic type is now the result of the combination of two alleles. For example: 1. AA 2. BB 3. CC 4. AB 5. AC 6. BC This system has a few problems of its own however. Inheritance becomes a bit messy; based on the above system, a type 1 and a type 4 could have either type 1 or type 4 children, but a type 1 and a type 3 would always have type 5 children, and a type 5 and a type 6 could have either type 3, type 4, type 5, or type 6 children. Also, it's difficult to justify why one particular combination would be non-magical but all other combinations were of equal strength. We can't just make allele C nonfunctional, because then there'd be no difference between types 1 and 5 and between types 2 and 6. You could get around this by making allele C be unable to function on its own, making type 3 non-magical, but to change the effect of allele A or B if its also present. This is perfectly biologically valid, but it still ties types 1 and 5 and types 2 and together somewhat. So this is now getting into the realm of exactly what these types of magic are, how they relate to each other and what common features they might have. An alternative explanation could be that two of the alleles, say A and B, have "opposite" effects that cancel each other out. Maybe the A and B enzymes recognize each other as foreign and try to consume each other, but don't mind themselves (obviously) and are okay with enzyme C. Or maybe the molecules they produce destructively react together (imagine if A gives you magic through the power of baking soda, C through the power of water, and B through the power of vinegar. Stupid example but hopefully it makes my point). This would be very similar to how blood type works, as discussed in [John's answer](https://worldbuilding.stackexchange.com/a/82522/1971). It doesn't have to be one gene, however. There could be two genes essential for magic, or three, or [six](https://worldbuilding.stackexchange.com/a/82530/1971). There are many increasingly complex ways this could work. I'll write more if I think of any that are particularly interesting. [Answer] # Pseudo-science and real science to follow First, a caveat - I don't know much about genetics, but I do know that it is complicated (read artistic licensing can be applied more or less liberally) and I'm really good with the [Punnet Squares](https://en.wikipedia.org/wiki/Punnett_square). Depending on how much you want to be tied to real principles of genetics, there are LOTS of ways to do this. The variables of note are (1) the number of "genes" used, (2) the number of "traits" used, and (3) how the geneotypes manifest phenotypes (including traditional dominant vs. recessive and more hypothetical (read likely not realistic) dominance schemes), and one assumption: possessing magic is beneficial and culturally desirable (this is import for consequences), and a few very, very needful simplifications. I shall refer to a person who has inherited magic as a Mage, a person who has not inherited magic as a Non, and the five magical branches as A, B, C, D, and E respectively. ## 1 gene, 5 traits, magic is recessive $$ \begin{array}{c\|c c} & \text{A} & \text{B} & \text{C} & \text{D} & \text{E} \\ \hline \text{A} & \textbf{AA} & \text{AB} & \text{AC} & \text{AD} & \text{AE} \\ \text{B} & \text{BA} & \textbf{BB} & \text{BC} & \text{BD} & \text{BE} \\ \text{C} & \text{CA} & \text{CB} & \textbf{CC} & \text{CD} & \text{CE} \\ \text{D} & \text{DA} & \text{DB} & \text{DC} & \textbf{DD} & \text{DE} \\ \text{E} & \text{EA} & \text{EB} & \text{EC} & \text{ED} & \textbf{EE} \end{array} $$ Inheritence Mage/Mage $$ \begin{array}{l\|l l} 1 & \text{A} & \text{A} \\ \hline \text{A} & \text{AA} & \text{AA} \\ \text{A} & \text{AA} & \text{AA} \\ \end{array} \space{}\space{}\space{}\space{} \begin{array} {c\| c c} 2 & \text{B} & \text{B} \\ \hline \text{A} & \text{AB} & \text{AB} \\ \text{A} & \text{AB} & \text{AB} \end{array} $$ [1] A pair of Mages of the same branch will always produce a Mage of that branch [2] A pair of Mages of different branches will always produce a Non Mage/Non $$ \begin{array}{c\|c c} 3 & \text{B} & \text{C} \\ \hline \text{A} & \text{AB} & \text{AC} \\ \text{A} & \text{AB} & \text{AC} \\ \end{array} \space{}\space{}\space{}\space{} \begin{array} {c\| c c} 4 & \text{A} & \text{C} \\ \hline \text{A} & \text{AA} & \text{AC} \\ \text{A} & \text{AA} & \text{AC} \end{array} $$ [3] A Mage and a Non with no common traits will always produce a Non [4] A Mage and a Non with a common trait will produce a Mage of that branch (0.5) or a Non (0.5) Non/Non $$ \begin{array}{c\|c c} 5 & \text{C} & \text{D} \\ \hline \text{A} & \text{AC} & \text{AC} \\ \text{B} & \text{BC} & \text{BD} \\ \end{array} \space{}\space{}\space{}\space{} \begin{array} {c\| c c} 6 & \text{A} & \text{C} \\ \hline \text{A} & \text{AA} & \text{AC} \\ \text{B} & \text{BA} & \text{BC} \end{array} \space{}\space{}\space{}\space{} \begin{array} {c\| c c} 7 & \text{A} & \text{B} \\ \hline \text{A} & \text{AA} & \text{AB} \\ \text{B} & \text{BA} & \text{BB} \end{array} $$ [5] Two Nons with no common traits will always produce a Non [6] Two Nons with one common trait will produce a Mage of that branch (0.25) or a Non (0.75) [7] Two Nons with both traits common will produce a Mage of one branch (0.25) or the other (0.25) or a Non (0.5) Consequences This would likely produce a natural caste system where 'noble' houses intermarry with noble houses of the same magical branch and carefully control the bloodlines. The common folk will periodically produce a mage by accident, quite scandalous! Some of these would periodically get married into the noble lines because the heart wants what the heart wants or to deliberately help with genetic diversity. These nobles would likely blend (a mixed region/country), resulting in few common born mages (because of genetic diversity), or separate (mono-branch region/country), leading to a higher frequency of common born mages (due to lack of diversity of nobles - sewn oats and all that). Mono-branch regions would have an incentive take prisoners from other mono-branch regions to diversify (and oppress) the common stock. Mixed regions seems the most likely if different branches can accomplish different things, but if similar effects can be achieved with each branch then both would be likely to occur. ## 1 gene, 6 traits, magic is dominant As above, but a 6th trait N is introduced. All co-dominant pairings can be exclusively Nons or exclusively Mages if following some dominance rules (AB always manifests as A, etc. -- several rock, paper, scissors, lizard, Spock style diagrams could map out all pairings) or some combination (AB always manifests as A, AC is always a Non, etc.). All A-E/N pairings are a Mage of the appropriate branch. All NN pairings are Nons. Consequences If co-dominant pairings are Nons, Mages are still rare, similar as magic recessive above. Pure Mages (AA) could be more powerful (due to purity) or less powerful (due to latent effects of N, perhaps a larger pool of power from which to draw -- hence NN are Nons that could theoretically be considered Mages with large pools to draw from but no way to expend it). If Pure Mages are more powerful then there will be little dilution in the bloodlines. If \N Mages are more powerful, bloodlines will be mixed and some children will be Nons and thus possibly shunned, cast off, executed, exiled, used for purely political marriages, etc. If co-dominant pairings (AB) are Mages, then Mages will likely be VERY* common. If Pure Mages (AA or AB) are more powerful than Non-Mage mixes (\N) then Nons will be second class citizens in many places. If Pure Mages are weaker than Non-Mage mixes then Nons will valuable property/breeding stock in some places and key figures of important houses in others. ## 2+ genes, 3+ traits Mages have one or more genes that determine if they are a Mage and one gene with 3 or more traits that determine what Branch of magic they have. If magic is recessive, the more genes required to be a Mage the fewer Mages there will be. If magic is dominant, the more genes that create Mages the more Mages there will be. With 3 traits, you would have 6 distinct pairs (AA, AB, AC, BB, BC, CC) or 8 permutations (treating AB and BA as different, etc.), which would be enough to map out to 5. The more combinations belong to a branch the more populous that branch will be, so this set up would be ideal if you wanted a magical ruling class (rare branches) and a magical laboring/middle class (common branches). You need 5 (or a multiple of 5, but 5 would be the most simple) to have all branches be roughly equally represented (see rock/paper/scissors/lizard/Spock comment above for how to chart that). A pairing of mixed people from mixed branches $$ \begin{array}{c\|c c} 1 & \text{MA} & \text{MB} & \text{NA} & \text{NB} \\ \hline \text{MA} & \text{MMAA} & \text{MMAB} & \text{MNAA} & \text{MNAB} \\ \text{MC} & \text{MMCA} & \text{MMCB} & \text{MNCA} & \text{MNCB} \\ \text{NA} & \text{NMAA} & \text{NMAB} & \text{NNAA} & \text{NNAB} \\ \text{NC} & \text{NMCA} & \text{NMCB} & \text{NNCA} & \text{NNCB} \\ \end{array} $$ M is the gene for Mages and N is the gene for Nons. If magic is dominant, MN could be a Mage or a Non depending on how you treat mixed branches (if A or B is dominant over the other, then it is still a Mage, if traits are co-recessive then it is a Non). If magic is recessive, MN is a Non regardless of branch traits. For multiple magic genes, it is similar, but the portion that is magic/non-magic shifts appropriately. [Answer] There's some good answers so far, but they have some issues. The blood type-style inheritance is on the right track, but you'd end up with a ton of children who didn't have the same magic type as either parent. For example, if a AA parent pairs with a BB parent, all the children will be AB, which would be a completely different phenotype than either parent. The allelic exclusion answer sort of works, but humans don't have the same allele inactive in all of their cells. Can't add another link, but google "Why women are stripey" for a bit more info. I'd like to suggest a sort of rock-paper-scissors inheritance instead, with 6 possible alleles at one locus. Here's a quick diagram to show what I mean:[![enter image description here](https://i.stack.imgur.com/4dmd2.png)](https://i.stack.imgur.com/4dmd2.png) A dominant to B and C * B beats C, D, E * C beats D, E * D beats E, F, A * E beats F, A * F beats A, B, C A punnet square color-coded by the resulting phenotype (I'm using MS Paint right now) looks like this:[![enter image description here](https://i.stack.imgur.com/UEYN4.png)](https://i.stack.imgur.com/UEYN4.png) Assuming that the 6 possible alleles are evenly distributed throughout the population, you'd end up with each phenotype represented by between about 14% and 20% of the population, which is a pretty even split. You can adjust the allele frequency or the rock-paper-scissors ring if you want a different distribution of phenotypes. Compared to the blood type example, you should end up with more children matching the phenotype of at least one parent. I believe that every pairing of parent genotypes would have, at worst, 50% of possible children matching at least one parent's phenotype. [Answer] Since you're looking for "clean breaks," you'd have to get "creative" with your application of genetics... As I commented, doing 4 magics and a single mundane is fairly easy, since we have 4 bases. Assuming a single base in the magic gene is the determinant for affinity, this would make your phenotypes AA, CC, TT, GG, plus the six mixed bases (AC, AT, AG, CT, CG, TG). The "pure" phenotypes would be magical, and the mixed pairs would be mundane. This implies that half the population has no magical ability, and the remaining half is evenly divided among the four types. If two people share the exact magic affinity, then they will have a child with that exact magic affinity. If they have differing magic affinities, then their child will ABSOLUTELY be mundane. BUT, if there is a magic and non-magic pair, the chance still exists for the child to share the affinity of the magic parent. Assuming you don't know the genetic makeup of the mundane parent, then the chance of them having no matching bases (and therefore will always have a mixed base child) is (3/4\2/4)=3/8ths, meaning there is a 5/8ths chance of sharing a base and a resulting 5/16th's chance of the child being magical. For a mundane/mundane couple, each has 6 possible phenotypes, making 36 possibilities. Each has a single "opposite" phenotype with no chance of magical offspring (1/6 of magic not being possible). Matching mundane phenotypes (1/6 chance) would give a 1/2 chance of magical offspring of either of the base genotypes. The remaining 24 matches have single matches, which lead to a 1/4 chance of magical offspring. Once you've got genetic sequencing, you can ensure that "matching bases" always exist among couples which raises your chance of a magical child to 1/2 for a magic/mundane couple, 1/2 for a mundane/mundane couple where both bases match, and 1/4 for a couple with only 1 matching base. Hypothetically, you could do this without sequencing if you prevented mundanes from marrying one another - that means a mundane from a given union will always have at least the base of the magical parent, and mixed magic union will have a mundane human with a known pair of phenotypes. This gets us to 5 traits, though, not 6. To quote [Wikipedia](https://en.wikipedia.org/wiki/Phenotype): > > The interaction between genotype and phenotype has often been conceptualized by the following relationship: genotype (G) + environment (E) → phenotype (P)* > > > A more nuanced version of the relationship is: genotype (G) + environment (E) + genotype & environment interactions (GE) → phenotype (P) > > > Basically, add in an environmental factor controlling gene expression that is the determiner between two phenotypes. How exactly this works could be tweaked to modify how common you want magic to appear. (*Note:* capital letters (ACTG) are the actual alleles, while lower case (actg) represent environmental factors contributing to allele expression.) If you want rare "pure" bloodlines, then the environmental factor MUST MATCH the inherited phenotypes in order for the offspring to be magical. So two AA's would NOT have magical offspring if the total phenotype is AA+(c,t,g factors). This would lead to cultures with highly regimented and ritualized environments created to preserve magic bloodlines. Conversely, you can hold that environmental factors *only* operate as determinants when the phenotypes are different, which keeps magic bloodlines "secure" and would not necessarily result in the above cultural effects. In either case, the final magic phenotype could exist among a "non-magic" mixed phenotype where the environmental determinant is unlike EITHER of the two bases. So an AC+(t or g) would be magical, while an AC+(a or c) would not. The environmental contribution basically "moderates" the two incompletely dominant magic alleles (normally mundane) and makes them "co-dominant," making this final phenotype "balanced" magic. This discrete magic phenotype could ONLY be brought about by marrying outside of your bloodline, and would presumably be a rare event. [Answer] To add a different solution, use a single gene expressed in 6 alleles: `A-E`, each corresponding with a magic type, and `P` providing power needed for the magic. You need both a specific magic gene and power for your magic to work. So `AP` (and `PA`) expresses as magic type `A`. Combinations like `AA`, `AB`, and `PP` are non-magical. This means that a magical couple has a 50% chance of getting a magical child and it doesn't matter if the parents express the same or a different kind of magic. Moreover, two non-magical parents `AA` (or `AB`) and `PP` have a 100% chance of having a magical child (but e.g. combining `AB` and `AC` leads to a 0% chance). This may fuel some interesting story. In case there's too much magic, add a non-functional allele `N`. ]
[Question] [ So I'm writing a story about a crew of scientists that explore the universe searching for a hidden knowledge in embed in the fabric of the space itself. More like to the Destiny's crew from [Stargate Universe](http://stargate.wikia.com/wiki/Stargate_Universe). Like their ship, I want mine to have some sort of FTL capability but not through hyperspace. It's very important that the ship does not go out of the space, like when you use a hyperspace drive, because the crew need to be constantly gathering data from the ship equipment, and do not warp the space around it like the Alcubierre Drive, because the will render the data useless, since space was warped. So, there is some way to achieve FTL travel like the one I'm proposing and being scientific correct? And yes, if possible I want to not suffer from time dilation due the speed. [Answer] TL;DR: "Scientifically correct" (according to current established science) and "faster-than-light travel" cannot be used in the same context without some form of negation. What you are asking for is not possible within the boundaries of science as we know it. Here's why: Our best model for this type of effects, insofar as I know, is special and general relativity. [Special relativity postulates](https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity) that colinear velocities are added according to the formula $$ s = \cfrac{v+u}{1 + \cfrac{vu}{c^2}} $$ for an initial velocity $v$ and a total acceleration $u$ (over some period of time) yielding a final velocity $s$. For small values of $v$ and $u$, this behaves like we are used to, because for such values, the fraction $\frac{vu}{c^2}$ is very small, so the term $1 + \frac{vu}{c^2}$ is very close to 1 giving $s \approx v+u$. Of course, in some situations, even with everyday velocities [this approximation might not be good enough](https://physics.stackexchange.com/a/79342/14091 "If I was on a bus at 60 km/h, and I started walking on the bus at a steady pace of 5 km/h, then I'd technically be moving at 65 km/h, right?"). However, look what happens if we set $v = 0.90c$ and $u = 0.10c$ (meaning that in an intertial reference frame, our initial velocity is 0.90 times the speed of light, and we increase our velocity by 0.10 times the speed of light). Intuitively, the velocity would come out as $(0.90 + 0.10)c = c$, but it turns out that this is not the case at all. Rather, using units of $c$ for simplicity: $$ s = \cfrac{0.90 + 0.10}{1 + \cfrac{0.90 \times 0.10}{1^2}} \approx 0.9174 $$ See what happens? In an inertial reference frame, our velocity only rose from $0.900c$ to about $0.917c$, an increase of 1.9%, even though we tried to raise the velocity by 11% ($0.10c$ out of $0.90c$). This effect becomes even more pronounced as your initial velocity approaches $c$ ($v \to c$). For example, look what happens if we are moving at $0.99c$ and increase our velocity by $0.10c$ (yes, I really mean that): $$ s = \cfrac{0.99 + 0.10}{1 + \cfrac{0.99 \times 0.10}{1^2}} \approx 0.9918 $$ for a 0.18% increase for the same effort that got us 1.9% starting at 90% of $c$. And of course, in the real world, these are both absurdly high values for $u$, reminiscent of instantaneous acceleration. Instead, we should be working with $u \to 0$ (because in the real world, the time over which we measure acceleration goes to 0), but since that's difficult to show in a single equation, I'll settle for $u = 10^{-12}c \approx 0.3~\text{mm/s}$ which isn't a totally unrealistic change of velocity over a short period of time given something resembling a real-world device trying to propel itself. Now look what we get if we start out at $0.90c$: $$ s = \cfrac{0.90 + 10^{-12}}{1 + \cfrac{0.90 \times 10^{-12}}{1^2}} = 0.900~000~000~000~189~999... $$ Our velocity increase, which we tried to make $\frac{10^{-12}}{0.90} \approx 1 \times 10^{-12}$, became $\frac{0.90000000000019 - 0.90}{0.90} \approx 2 \times 10^{-13}$. We only got 1/5 of the increase that we spent the effort for, and at 90% of $c$, we are still a good long ways away from $c$. It only gets worse from there. Eventually, this means that the energy cost of increasing your velocity grows in an exponential fashion. If you work the math all the way, effectively solving $$\lim \limits\_{v \to c, u \to 0} \cfrac{v+u}{1 + \cfrac{vu}{c^2}}$$ you end up with an energy requirement that grows toward infinity as you get closer and closer to the speed of light. Because instantaneous velocity changes are not possible (because of inertia, for one thing), you can't simply "jump past" the difficult part of the acceleration curve. Because your spacecraft will, at every instant, have an instantaneous velocity (along some vector) and an instantaneous acceleration ($\vec{a} = \vec{\Delta v} / \Delta t$ for some $\Delta t \to 0$), you will thus only ever be able to (with humungous energy expenditure) approach the speed of light, but you will never be able to reach the speed of light. As your velocity increases, the marginal utility of any given acceleration (within the local frame of reference) decreases; you get less and less (inertial reference frame) acceleration out of any given amount of effort. Because inertial reference frames are what we are generally concerned with when going places, this means you work exponentially harder but get exponentially less utility for your efforts. If you want a single formula that explains why faster-than-light travel is impossible in the real world as we currently understand it, the mass-energy equivalence $E=mc^2$ (as suggested [by AndreiROM](https://worldbuilding.stackexchange.com/a/46672/29)) isn't what you are looking for (in fact, it might even to a limited extent be your friend, if you can figure out how to do the mass-energy conversion); rather, the one you want is the relativistic colinear velocity addition formula and an understanding of how it behaves as $v \to c$. [Answer] There are many classic ideas on how an FTL drive might work. As other answers have noted, currently there are no actual science-based FTL drive ideas available; FTL travel appears to be impossible. One of the classic ideas is quantum jumps, where the whole ship teleports a short distance instantaneously, and then repeats the jump at a high rate. For whatever reason, the teleportation can't work at a great distance, but a ship can send itself a short distance. The ship can jump from being motionless in one place to being motionless in another, nearby place; this avoids the huge energy cost of accelerating up to a significant fraction of the speed of light. The seeming motion can be called "pseudovelocity". (I know I've read stories featuring an FTL drive that works this way but I can't think of the names of the stories.) During the time that the ship isn't jumping, it's at rest in the normal universe, and cameras or other instruments could take measurements. But the data might resemble a time-lapse series. How does the teleportation work? Handwave handwave quantum physics something something. But it's a classic old tradition: the FTL will work just how it needs to work for your story. P.S. It may also be possible to use a space warping drive, and then explain that the data is computer-processed to remove the effect of the warping. But I think the quantum jumping would work well for your story. [Answer] I am aware of only two scientifically postulated methods of FTL drive. The first has been mentioned on this board quite a bit and I thought was originally posed as an answer here, the [Alcubierre Drive](https://en.wikipedia.org/wiki/Alcubierre_drive). The second is [Quantum Tunneling](https://en.wikipedia.org/wiki/Quantum_tunnelling#Faster_than_light). ## Alcubierre Drive > > ...a spacecraft could achieve apparent faster-than-light travel if a > configurable energy-density field lower than that of vacuum (that is, > negative mass) could be created. > > > Rather than exceeding the speed of light within a local reference > frame, a spacecraft would traverse distances by contracting space in > front of it and expanding space behind it, resulting in effective > faster-than-light travel. Objects cannot accelerate to the speed of > light within normal spacetime; instead, the Alcubierre drive shifts > space around an object so that the object would arrive at its > destination faster than light would in normal space. > > > Essentially, the object does NOT move faster than the speed of light locally. In its frame of reference it is moving slower than light. The Alcubierre Drive compresses space in front of the ship and stretches space behind the ship - essentially moving space. 2-D representation of Alcubierre space stretching: [![2-D representation of Alcubierre space stretching](https://i.stack.imgur.com/0th2d.png)](https://i.stack.imgur.com/0th2d.png) ## Quantum Tunneling Any object can perform quantum tunneling, but the math of the problem shows that even for very light mass objects, the event is unlikely. That we see tunneling is because of the large number of objects observed. As the mass of the object or width of the potential barrier increases, the likelihood drops. When you get to single macroscale objects performing tunneling events across interstellar distances, the average amount of time for that event to happen is a number with many, many zeroes. > > Quantum tunnelling or tunneling (see spelling differences) refers to > the quantum mechanical phenomenon where a particle tunnels through a > barrier that it classically could not surmount. This plays an > essential role in several physical phenomena, such as the nuclear > fusion that occurs in main sequence stars like the Sun... > > > and > > Tunnelling is often explained using the Heisenberg uncertainty > principle and the wave–particle duality of matter. Pure quantum > mechanical concepts are central to the phenomenon, so quantum > tunnelling is one of the novel implications of quantum mechanics. > > > and > > It is possible for spin zero particles to travel faster than the speed > of light when tunnelling.[3](https://i.stack.imgur.com/0th2d.png) This apparently violates the principle of > causality, since there will be a frame of reference in which it > arrives before it has left. However, careful analysis of the > transmission of the wave packet shows that there is actually no > violation of relativity theory. > > > Now consider the barrier as the gravity hill sloping upwards away from your star. If used as an SF drive, the Quantum Tunnel event would cause your ship to disappear from this gravity well and spontaneously appear in another deeper gravity well somewhere else. Quantum Tunneling of an Electron: [![Quantum Tunneling of an Electron](https://i.stack.imgur.com/c71Jf.jpg)](https://i.stack.imgur.com/c71Jf.jpg) During Quantum Tunneling a particle appears on the other side of the potential barrier instantly (e.g. faster than light). For most particles, a delay at the barrier makes the total velocity of the even slower than light, even though the particle will appear spontaneously on the other side of the barrier. However, for spin zero particles calculations show that the entire event happens FTL. There are three big drawbacks to using this in SF though. ### It's improbable The first is that the probability of the event is inversely related to the mass of the object. For particles of the mass of a proton it becomes extremely unlikely to happen. To observe this happening to a specific macroscopic object (say a person or a space ship) you'd have to watch it for an *extremely* long time (a number with a huge number of zeroes in it). ### Only spin zero particles go FTL The other problem is the key words "spin zero particle" and not particles like electrons and protons. So it is scientifically conceivable that this could be used to transmit some things at FTL speeds. ### We can't make it happen Like other things quantum mechanical, there's simply a probability that the event happens. The only way we know how to manipulate the event is by changing the particulars of the particle or the barrier. We can't otherwise influence the likelihood of it happening. The reason that we can see this happening in a sample set is because there are so many particles and to us we don't care which one it happens to. The other is the very light mass of these particles. ### Other Stuff I've often toyed with the idea of inventing an FTL drive using similar principals but adjusting the particulars to meet the needs of my SF Universe. I haven't developed a consistent set of rules for it yet though. If you wish to use this as the basis of your drive, you'll want to consider the answers to these questions and what they mean to your Universe, even if you don't explain the particulars to your audience: * How do we account for the very large mass of the object we want tunneled? * How do we account for causing the event to happen when we want it to? * How do we account for causing a specific object to tunnel rather than just any old object? [More information on Quantum Tunneling](https://en.wikipedia.org/wiki/G%C3%BCnter_Nimtz#Experiments_related_to_superluminal_quantum_tunneling). > > ... Actually, Nimtz and coworkers observed that the measured tunneling > time is spent at the barrier front, whereas inside the barrier zero > time is spent. This result was observed in several tunneling > barriers and in various fields. Zero time tunneling was already > calculated by several theoreticians > > > [Answer] There are several reasonably science-based forms of FTL travel in SF and usually written by SF writers with a science background. Here are some of the better examples. If I've missed anyone who should be on the list, please let me know. Poul Anderson's quantum mechanical micro-jumping pseudovelocity drive. See his Flandry of Terra series, the Polesotechnic League series, and the Psychotechnic League series of novels. For more information about Poul Anderson's science fiction go [here](http://www.sf-encyclopedia.com/entry/anderson_poul) Gregory Benford's tachyon jump. It assumes bradyons (slower-than-light particles) are virtual tachyons. The jump works by converting the vessel's bradyon matter into tachyons which move an infinite velocity from point A to point B where it reverts to its former bradyon matter state. Reaction mass is expelled during a jump, presumably to shift the vehicle's position. See The Stars in Shroud (1977). Note: this is also the revised edition of Deeper Than The Darkness (1970). Benford, who as a working physicist was a co-author of antitelephone paper that came down against tachyons, no longer uses tachyons for FTL travel in his SF. For example, in Foundation's Fear: The Second Foundation Trilogy (1997) wormholes are the mechanism for FTL travel around the Asimovian Galactic Empire. Stanley Schmidt's Rao-Chang tachyon drive. FTL ships 'shift' from the bradyon state to their equivalent tachyon state. Schmidt published an article "How To Move the Earth" in Analog (May, 1976) which has an explanation for this fictional tachyon drive. See The Sins of the Fathers (1976) and Lifeboat Earth (1978). Robert L Forward uses wormholes for FTL travel in Timemaster (1992). Somewhat eccentrically the wormholes are created by friendly space-dwelling organisms which lay them, more or less, like eggs. Stephen Baxter has wormholes supported by exotic matter structures for FTL travel in his Xeelee Sequence novels. See [here](http://www.sf-encyclopedia.com/entry/baxter_stephen) for more details. These are nothing more than science-based forms of FTL travel. None of the authors necessarily believe this is how FTL travel will be accomplished, if it can ever be accomplished, the role of the science is to make their versions of FTL travel appear to be scientifically plausible. This is what the OP wanted for his story. Here are some examples. [Answer] I think I got something workable. But you have to invent a type of exotic matter that I'll call "negative mass" for now, not to be confused with antimatter. In our universe you have to overcome the following problems, 1. the faster you go, the more mass you have, meaning you need even more energy to move. That means you keep pumping in energy and never quite get to c. And 2. speed necessarily means slower time for you in relation to someone not moving. That's the way mass energy equivalence and special relativity work. So you'd have to change something about those. To counter 1) maybe you have some way of creating "negative mass" the faster you go, that way you don't get more and more massive. For bonus points you could put another theoretical speed limit, maybe you asymptotically approach instantaneous arrival in your universe, some kind of "infinite acceleration." You wouldn't have to necessarily explain why but it would serve to eliminate the going-faster-than-light = going-back-in-time problem. To counter the time dilation effects you really need to alter something pretty fundamental to the way we understand acceleration and relative velocities, just understanding special relativity, as it currently is, is really hard. Again, I would just balance it out and say that the "negative mass" simultaneously creates a kind of time acceleration, increasing your progress through time. Or you could even have a whole other time engine just to accelerate your progress through time if you want and leave the negative mass out of it. Thinking about the universe like this makes my head hurt because I don't know what ramifications this type of meddling would have. For example, if you accelerated up to c with your negative mass generator on, what would the lorentz transformations make you look like? If c isn't a speed limit anymore, maybe you would look normal. Another example would be what would the bouncing photon look like on a train going at c? It's still traveling farther for a stationary person. The problem is people going different speeds don't agree on what they see. Fundamentally I don't know how to imagine a universe where c isn't a speed limit but where "infinite acceleration" might be. I'm sure real physicists are furrowing their eyebrows and shaking their heads at me now. [Answer] Your main requirement is: the crew need to be constantly gathering data from the ship sensors. So you don't want to just jump to the destination or move in a different realm. As explained earlier by steveha, you can use some short-range jumping tecnique to give a “pseudovelocity”. I recall a [series of connected short stories](https://scifi.stackexchange.com/a/134394/38557) by [F. M. Busby](https://en.wikipedia.org/wiki/F._M._Busby) expanded into a novel where this was explained as arising suppressing the normal rate of "appearances". > > "The trick is that space and time are quantized. If you don't know what that means, wait and ask me later. Mainly, the universe doesn't exist continuously. It pulsates—appears and disappears at a rate much too high to measure. So when you move you do it by vanishing at one point and reappearing at the next—normally. > > > "Ordinarily, in moving we hit every point along the way. Skip Drive suppresses our appearances at most of those points. We beat lightspeed because it's the ins and outs that use up time and energy, not the motion itself." > > > An interesting side effect they later figured out is that this also allows drift between timelines! The travelers may arrive to a world with different history than when they left. The “make small jumps” idea can be applied to adapt any FTL mechanism to your need to have a pseudo-path in normal space and see out. For example, use wormholes: but only a billion miles at a time. You find a wormhole in the quantum foam that goes to the desired destination, but as with electron probability clouds and such, the probability of finding one decreases with distance. So they find one with an endpoint about a billion miles away in the right direction, amplify it to ship size, open the ends and traverse. You can find any number of reasons why the jump distance is limited. Space warp in the manner of Alcubierre Drive (but without the insane energy requirements)? The very point that the ship can't see out at all makes it difficult to navigate. So it makes a series of small jumps and takes pictues at each jump, making it seem like normal motion to those watching the screens. But this is a survey ship or something, with the purpose of gathering readings along a survey route, right? So even if the technology were not limited, the ship would be made that way. A passenger liner goes into hyperspace, flys around in this other realm for a few days having nothing to do with out universe and what's to be found in the space between here and there, and returns to normal space there. But the survey ship wants specifically wants to see what lies along the route in normal space, so it goes into hyperspace for a minute, drops out, and records what it sees, then repeats. --- Of course, [any means of FTL can become time travel](https://worldbuilding.stackexchange.com/a/47038/885), so you need to be careful in explaining it or designing it so as not to be a general purpose time machine as well. But, you can turn the relationship around. Consider making a normal journey at relativistic speeds, taking (say) 5 years to cover the distance in the reference frame of the destination planet. Then, use a time machine to go back 5 years! Now the ship arrived instantly, right? But instead of jumping back in time when you get there, do it incrementally. The ship will appear in a short length of voyage from A to B during time t₁ through t₂ (say, one day), then jump back in time a day, and be seen in the outside world to travel from B to C, also, in the time interval from t₁+ε to t₂+ε, and so on, all along the path of its journey. Potentially you could make each leg as short as the length of the ship. [Answer] First of all all movement suffers from time dilation what so ever and the amount is mathematically defined, so by hard physics (as we understand it) you'll always get this if you're physically moving from point A to point B. Even as citizens of Earth we see this dilation compared to a completely stationary particle (not rotating, orbiting, or expanding with the universe) but the difference is fairly small. Also as we understand velocity currently you can't actually travel faster than light, so if you want to stick to known science and have to go faster than light can we're kind of forced to abandon normal means of getting from point A to point B. However we are already making [making minor steps towards actual teleportation](http://www.sciencealert.com/physicists-have-quantum-teleported-a-particle-of-light-across-25-kilometres "minor steps towards actual teleportation") which negates the actual travel from point A to point B, and the teleported material would never enter 'hyperspace' or anything like it. I think it's the only thing that will work for your idea. Alternately you could use the classic idea of wormholes to bridge two spots in space, but it should be noted [that we have no experimental evidence for them whatsoever.](http://www.scientificamerican.com/article/follow-up-what-exactly-is/) Basically they're fiction, not science, like magic or the Force. But they sound sciency. [Answer] Travel is defined as the movement of an object from Point A to Point B via the space inbetween. Travelling faster than light speed is not possible, the only way an object can appear to move faster than light is to warp space-time, typically with a wormhole, though again this is not travelling, since you do not occupy the space inbetween. [Answer] One of my old favorites, although I'd doubt its scientific accuracy is the Jump Drive from C.J. Cherryh's fiction work. <https://en.wikipedia.org/wiki/Jump_(Alliance%E2%80%93Union_universe)> --- In the Alliance-Union universe faster-than-light (FTL) ships have two major drive systems, slower-than-light (STL) thrusters and FTL jump engines. The jump engines comprise vanes that are attached to the outside of the ship. When the vanes are pulsed, they generate gravity waves which create a field, or "bubble", around the ship that pulls it (and anything else in the field) along the interface between realspace (Einsteinian space) and hyperspace (jumpspace). Jump takes place between two massive objects, called jump-points, which are generally stars, brown dwarves, or "rogue planets" sufficiently massive to make "pockmarks" in hyperspace. Prior to jumping, the ship's navigators calculate an outbound vector, targeting the destination jump-point with direction and speed. The ship accelerates along this vector with a long STL burn until it is clear of the current jump-point's gravity well and the requisite velocity is reached. The jump engines are then engaged and the ship enters the interface between realspace and hyperspace. In this quasi-state of being half-in and half-out of hyperspace the ship is drawn along the interface to the nearest gravity well on the outbound vector, the destination jump-point. Here it re-enters realspace, travelling at the same speed and direction it entered the interface. Back in normal space the ship dumps velocity by cycling its vanes to graze the interface before the STL thrusters take over. It is possible to pass through several jump-points without slowing down, but this is risky as it can cause the ship's velocity to become uncontrollable. --- Long story short, it's sort of a gravity winch. If you point yourself in the right direction, and speed up to near FTL, the drive can grab hold of a gravity well and drag you along with it, like a stone skipping across the surface of a pond. The books explain the drive systems a little differently; it's not that the ship enters hyperspace, it's more akin to dropping a weight into a whitewater stream just below a mostly-calm surface while kayaking. You don't get pulled underwater, but along the surface. [Answer] We can take a page from the classics that first tried to get around Einstein's speed limit: Inertialess Drive. E. E. "Doc" Smith has one of the better known examples of this type of drive in his Lensman series. This drive gets around the the "mass increases to infinite" issue by proposing a method that stores or hides the mass of the ship from the universe. With zero mass, even the smallest thrust could, theoretically, push a ship an infinite distance at infinite speed. However, any interstellar material would instantly stop the ship. So the speed of the ship ends up being whatever speed balances out the thrust with the drag of the interstellar medium. One issue is that you retain the velocity that you had when you engaged the inertialess drive. So, ships would have to thrust very hard at their destination to alter their velocity to the velocity of the object they wish to approach. If you can hand wave the mass negation, you have your "scientific" FTL drive. The fun part is that it comes with a bunch of issues that the characters absolutely must deal with. [Answer] I have already thought of this idea for my story, and will gladly share it with you now. This solution DOES fit your criteria even though it requires that the multiverse theory be true. The ship stays in the universe, does not suffer time dilation, and does not disrupt the space around it at all. Many of the answers above mine have one common limiting factor: the laws of physics. Nothing can go faster than light. However, my FTL drive does something special that involves different laws of physics. # 1. Materials Needed An atom called "Hyperium" or colloquially known as "FTL Fluid" is used. Negative ions of Hyperium are put into a pistol-shaped engine. A layor of positive ions surrounds the ship, easily created by making the outer layer of the ship from Hyperium metal (Fe2HyC4). For a tie-fighter sized ship, the engine only needs to be pistol sized; for a star destroyer, it would have to be as big as two or three tie-fighters. So, you need: a FTL engine, a bullet sized amount of negative Hyperium ions that is relative to the size of your engine, and an outer coating of positive Hyperium ions. # 2. How does it do it? When the engine is started up, it electrifies and shoots a blast of Hyperium. This unstable element splits apart into two, but both parts are connected to each other and exists in the same space. One part zooms off in this universe, touches the field of positive ions, and gets stuck. The other half zooms off into a different universe that is extremely small compared to ours and empty as well. Why does it go there? Because of its electrons configuration and instability and whatever are aligned so that the electron blast charges them into the other universe. Read this next part carefully. Once that part of the Hyperium blast enters the other universe, it is still going the fast speed BUT it is in a smaller universe at the bigger universe speed, so is going relatively uber overly faster than light speed. But it is connected to the other Hyperium, where the ship is. And that Hyperium is connected to the other ions. And the ship is connected to that. So the ship blasts off at the relatively uber overly faster than light speed; both universe reflect each other for the benefit of the ship drivers. But wait, what if you want them to only be able to go slightly over the speed of light? No problem. Many different society, planets, or peoples have different methods for making this engine. Some are better at it than others, meaning that YOU the writer/designer get to decide how fast their engine is. Were they excellent at making it and can go across galaxies in the blink of an eye? Or are they not very good, and can only travel between planets in that time? After your journey is done, simply sever the link between the Hyperium and the ship via another electric blast. The ions will become temporarily not-attracted, flinging the Hyperium blast into oblivion and instantaneously stopping the ship. Also, to the crew, there doesn't appear to be a sudden OOF from stopping and/or going; [insert excuse with science here that relates to trans-universe thing]. # 3. Pros This ship requires Hyperium to exist. Otherwise it cannot. That means you can choose if, in your universe, the element is very rare and only elites have it, or if it is common and everyone has a FTL drive. As aforementioned, the speed of the ship can also be decided to fit your needs as the designer. The trans-universe thing causes NO time dilation because the other universe doesn't have that physical law. The trans-universe thing causes NO cross-universe travel for the ship; only for the Hyperium. That's actually a lie, because the ship also becomes partially embedded in that universe, still able to detect things. The only parts that are effected are the laws of physics limitations, not the ship's ability to collide with objects. The engine could have a cool down or not; as the designer of your universe, you decided how efficient their engines are. For plot purposes, any different limitations can be added or changed. Perhaps your FTL drives needs [some other substance] to function? # 4. Cons If you're going really fast, you might miss your destination. But you can slow down gradually, maybe. This engine is kind of cheaty because it often answers questions with, "How? Because the other universe has different laws physics. How does that effect things? Because it's science!". If I knew some complex math and physics, I could probably actually say, "Well, A happens because B times C equals the square root of A!". However, if you don't mind that, than I humbly think this is an answer to your question. [Answer] In addition to the problem of a lack of ideas on FTL drives meeting your requirements there's an even greater problem: Special Relativity. Now, there's no question that it's not the final answer as to how the universe works but it's been tested enough that it's obvious that it's basically correct, although there might be edge cases it doesn't handle well. (Think of how Einstein displaced Newton—edge cases only, for almost everything we do we use Newton's answers.) Einstein prohibits accelerating through the speed of light, although there is no prohibition on a system to transform your ship into tachyons for the duration of your voyage. However, this enters into the realm of paradoxes and I do not believe that a solid object could thus be transformed. The transformation field can only propagate at c—but the part of the ship that's already transformed must take off at >c. This means your ship is dismantled at the subatomic level by the transformation. This basically says that any FTL transport system must somehow leave the universe in order to work. (I see nothing precluding a tachyon-beam communicator however, other than the issue of paradoxes.) [Answer] You could possibly use some kind of temporal warping around the ship. This would allow the data to filter in, albeit at a much accelerated rate. While this would leave the ship trapped in the future, with temporal warping systems you could either throw the ship and crew back in time or throw the universe around you forward in time. ]
[Question] [ [I made a post a while ago about how to saddle a dragon.](https://worldbuilding.stackexchange.com/questions/214095/dragon-riding-question) I recently remembered that, and another question came up: how to pilot a flying animal? Land animals tend to run in the direction their heads are pointing, but an animal flyer may well look to one side and keep flying forward. So, as I see it, reins are useless(mainly because my characters lie on the animals, they don't sit, the link has an answer that convinced me to make this change); besides, they can irritate the animal and you don't want to annoy an animal that can make you free-fall from the clouds to the ground or devour you or attack with fire (dragon) or lightning (thunder bird), for example. The way Hiccup pilots Toothless would only work for an animal that has a long tail with a part missing. Depending on the turbulence, the wind will prevent the animal from hearing the pilot tell which direction to go. Note: it has to be a method that doesn't use magic, so even those who don't have magic can pilot a flying animal. [Answer] You train the animal to respond to commands. Compare to riding a horse: if you are a decent rider, you don't\* direct the horse by yanking its head around. You give it very gentle cues, either a short tug on the rein, or neck reining: <https://www.equisearch.com/articles/direct-approach-neck-reining-17386> You also use leg & weight shift cues. If you're really good (I'm not), you don't really need reins at all. Look for videos of Stacey Westfall, for example. Also, your horse will often turn its head to look to the side while you're riding. Quite often at the walk, less so at a trot, and seldom at a canter or gallop. They can also be trained to respond to voice commands. (Maybe: I'm not sure whether they're understanding the voice, or subtle body/posture cues.) \Except in rather limited circumstances, for instance if the horse bolts and you need to do a one-rein stop: <https://horseandrider.com/western-horse-training-tips/problem-solved-with-warwick-schiller-one-rein-stop> [Answer] Follow the mouse.* [![harlock rides the flying cat](https://i.stack.imgur.com/9ZHfY.jpg)](https://i.stack.imgur.com/9ZHfY.jpg) The rider of this flying mount has gotten its attention with the mouse toy. By positioning the toy above, left, right or below the mount, this intrepid rider can induce his mount to take flight and then follow the toy. [Answer] > > Land animals tend to run in the direction they are looking, > > > You assumption is wrong. [![enter image description here](https://i.stack.imgur.com/0PGyX.jpg)](https://i.stack.imgur.com/0PGyX.jpg) [Horses](https://veteriankey.com/equine-vision/), which are the epitome of ridable animals, have 146 degree of monocular vision on each eye, and just 65 degrees of binocular vision. They look well on their sides while they move forward. [![enter image description here](https://i.stack.imgur.com/R1wVp.jpg)](https://i.stack.imgur.com/R1wVp.jpg) And the first reaction to a stimulus like the one given by reins is to move away from it, so I don't see how reins can be ineffective. Alternatively, you can use stroke on the neck to give the direction to the ride. [Answer] As you would do with a hand glider, by shifting your weight. The rider wants to dive? They lean forward, then backward to stop the dive or to go up. Slightly leaning on a side will push the animal to turn. Thus the rein can be used to keep the balance or few extra commands like telling the animal to land. [Answer] # Theory For any vehicle moving in 3 dimensions, you need to control the [roll, pitch, and yaw](https://howthingsfly.si.edu/flight-dynamics/roll-pitch-and-yaw) For a flying animal, I'm thinking reins to control the direction similar to the style of a [Two-line sports Kite](https://en.m.wikipedia.org/wiki/Sport_kite). # Details The driver will have two sets of reins. one in each hand. Each set of reins (left set/right set) is connected to something like the handle from a [U-Controled model airplane](https://en.wikipedia.org/wiki/Control_line). Think of it as a stick that you hold in the middle with one line at the top of the stick and one line on bottom. From the side, you'll see the reins connected off center to the bit. one is connected above the bit while the other is connected below the bit. pulling on the correct ones evenly (both up or both down) will give you pitch control (up/down). Pulling evenly on one of the sets of reins (left or right) will give you yaw control (left/right) like a horse. Pulling unevenly on both sets of reins, maybe even a twist, will give you the role control of the animal. (basically, you want the head to twist) [![photo chopped side view of a prototype bit and reins](https://i.stack.imgur.com/xaLCG.png)](https://i.stack.imgur.com/xaLCG.png) [Answer] ## As a General Rule, You Ride and Animal, you do not Pilot it Piloting is a system where by you have direct control over a vehicle. Riding is different, this is where you are on an animal that has free will, and you are communicating to it what you want it to do... and it then chooses whether or not to listen. So, reigns do not make a horse do anything, they are just used as a tool to signal to the horse what you want it to do. If a flying creature were similarly intelligent, it could be taught to respond to these cues the same regardless of whether you are actually changing the direction of the animal's head... but this is not a question about "riding" a flying animal, this is a question about "piloting" one. ## This is Where Biorobotics Comes In To truly "piolet" an animal, you must first turn it into a [bio-robot](https://en.wikipedia.org/wiki/Remote_control_animal). Bio robots are animals that have been fitted with remote control devices that over-ride its natural free will giving the operator direct control over its locomotion. Actual flying animals that have been piloted before include cockroaches, beetles, and pigeons. > > it has to be a method that doesn't use magic, so even those who don't have magic can pilot a flying animal. > > > It's not magic, it's science... though I understand if you are going for a typical fantasy setting that this much science may not be allowed. The good news is that [Clarke's 3rd Law](https://en.wikipedia.org/wiki/Clarke%27s_three_laws) also works in reverse in that any advanced technology can also be explained my magic. Just like you don't need to be an engineer to pilot a plane, you do not need to be a wizard to piolet an animal that has been subjugated by magic... as long as the wizard creates a usable User Interface. You could have a wizard implant magical devices that emit a slight electrical current when touched into a dragon's brain such that you have "buttons" on the back of its head that a non-magic user could press to stimulate the dragon into turning in various directions. [Answer] As has been mentioned, training would most likely be trivial if the animal were as intelligent as say a dog, cat or horse. If not, I could imagine something akin to the methods the Fremen used in Frank Herbert's Dune series. In the stories, there are people called the Fremen who ride giant sand worms that typical travel below the surface. They use a device to attract the worm to the surface, and then lodge a "hook" under one of it's scales. It doesn't hurt the worm much as such, but the worm turns the to lift the scale up away from the abrasive sand. That has two effects; it pulls the Fremen up to the top of the worm, and prevents it from submerging due to the irritation the sand would create. Your flying animals could possible be used in a similar way, depending on their anatomy. Perhaps they have sensitive places on their bodies that could cause them to turn when mildly irritated, and in time they could learn to do this with only a mild tug so as to prevent that. Even something like a long stick designed to tickle something like whiskers, causing them to turn their head and by reflex it makes them turn. Alternatively something attached to a far wing joint or tip, so leverage could be used to pull the wing up and down. Even a small movement should produce a dramatic change in direction; notice how little an aircraft's ailerons move to make it bank. I could imagine an elaborately constructed "saddle" complete with levers and pulleys with multiple thin ropes and wires designed to produce subtle movements in direction. The wires could be contained in a spring-loaded device that retracts when the animal lands or draws the wings inward. Perhaps skilled craftsmen could create super strong "mithril" or "adamantite" flying rigs custom made for your animal, decorated with ornate gold or gems, a sign of the prestige or status of the rider. [![enter image description here](https://i.stack.imgur.com/hmIfY.png)](https://i.stack.imgur.com/hmIfY.png) ]
[Question] [ ## BACKGROUND I'd like to create a world that includes pyrokinesis, the ability to heat and even combust materials at a distance. This is a low-magic setting, so what I have in mind is not very flashy. I'd like my mages to be able to heat good thermal conductors, spark combustibles, and that's it. For anything flashier it's BYOB (Bring Your Own Blackpowder). The mechanism they use to conjure heat is innate and handwavy, to be left ambiguous. The pyrokinetics believe they get their power from the sun. --- I want to be carefully consistent about measuring what my pyrokinetics can and can't do. Ideally, I'd like to know that a trained pyrokinetic can create X amount of heat inside a body of material over whatever time and distance, and then plug that into a formula and see how hot the material gets, whether it catches fire, etc. Strangely, I can't find any plug and play methods of efficiently estimating spontaneous combustion, so I've had to turn to thermodynamics in general, about which I know only a very little. My best bet seemed to be the formula for [heat transfer](https://www.khanacademy.org/science/physics/thermodynamics/specific-heat-and-heat-transfer/a/what-is-thermal-conductivity) but I quickly realized that (naturally enough) it assumes heat is being transferred from one object to another through a two-dimensional surface, rather than being produced within a three dimensional object. This seems like it would skew my results. I also read several articles on thermal radiation, but while that seemed promising I didn't understand it well enough to apply it. (There may well be obvious solution I'm looking right past.) --- ## QUESTION * What's the best way to calibrate and estimate the abilities of a pyrokinetic, along the lines described? [Answer] There are only two numbers of interest, energy and power. * Energy is how much heat can the magician produce; it is measured in [joules](https://en.wikipedia.org/wiki/Joule), or small calories (1 cal = 4.2 J), or kilocalories (aka [food calories](https://en.wikipedia.org/wiki/Food_energy), 1 kcal = 1 Cal = 4.2 kJ). A human consumes (that is, dissipates) about 2000 kcal (8.4 MJ) per day at rest, more if he is male, less if she is female; a man employed at heavy manual labor uses some 4500 to 5000 kcal (19 to 21 MJ) per day. * Power is how much heat can the mage produce per second; it is measured in [watts](https://en.wikipedia.org/wiki/Watt); 1 watt is 1 joule per second. At rest, a human dissipates about 100 W; a trained athlete can sustain about 250 to 300 W of mechanical effort, using up some 750 to 1000 W of stored energy (muscles have an [efficiency](https://en.wikipedia.org/wiki/Energy_conversion_efficiency) of about 30% at converting the stored chemical energy into mechanical energy). So if the magicians have a metabolism similar to regular humans, the only magical property being their ability to project heat, one could assume that a trained magician can project a total of about 750 to 3000 kcal of heat per day, with a power of about 250 to 1000 W, depending on how efficient is the mechanism which projects the heat; specifically, 750 kcal / 250 W at 25% efficiency, up to 3000 kcal / 1000 W at 100% efficiency. If we take the higher numbers, 3000 kcal (12.6 MJ) is enough heat to boil off completely about 4.8 kg (1.2 U.S. gallons) of water; supposing the magician is able to transfer a power of 1000 W, completely transforming that amount of water into vapor would take about 3 hours 30 minutes. (Assuming standard pressure and water starting at 20 degrees Celsius.) --- To boil off 1 gram of water: * one first needs to warm it up from 20° C (assumed) to 100° C; this uses (100 − 20) \* 4.2 = 336 J; * then one needs to supply the [heat of vaporization](https://en.wikipedia.org/wiki/Properties_of_water), 2.26 kJ. So overall one needs 2.6 kJ to boil off completely 1 gram of water; dividing 2.6 kJ/gram into 12,600 kJ of available heat we get 4,859 grams. [Answer] In addition to AlexP great answer, if you want to measure heat, then you are referring to a [calorimeter](https://en.wikipedia.org/wiki/Calorimeter), my favorite being the [bomb calorimeter](https://en.wikipedia.org/wiki/Calorimeter#Bomb_calorimeters). In a real world calorimeter, heat is generated inside a container, e.g. via combustion, or as a product of a chemical reaction. The exchange part happens entirely within the instrument and it is needed to measure the heat. To simplify the process: the pyro-agent heats a target metal ball inside the inner container of the calorimeter. The heating occurs from a fixed distance and for an agreed amount of time. The outer shell of the calorimeter is made of refractory material. Inside this shell there is water, and another container, surrounded by a thin metal pipe, acting as a heat exchanger. Inside the inner container the metal ball is held in place by rods of refractory material, such that the only heat exchange is with the air around the ball. As the air heats up, it expands and warms up the water around the inner container via the heat exchanger. The change of water temperature is measured on a roll of paper by a pen connected to a thin rod of metal submersed in water and coming out from a tiny tiny hole at the top of the instrument. The difference between the temperature prior to heating and the maximum temperature reached by the water is the $\Delta T$ you have been looking at. The relevant formula is $\Delta \text{Energy} = C \* \Delta T$ where $C$ is the capacity of the calorimeter, as explained [here](https://en.wikipedia.org/wiki/Calorimeter#Bomb_calorimeters). [Answer] Raise the average temperature of the grey matter between an enemy's ears by 0.7 degrees Celsius and their combat effectiveness falls to zero. They will be lucky to survive without brain damage. Using @AlexP's math, that is 1300 grams (of mostly water) raised 0.7 degrees equals 910 Joules (roughly a KiloJoule), to take down any opponent at any reasonable distance. In a pre-firearms world (primitive thermometers), beings, with such an ability, would be overwhelmingly powerful. They would literally possess the power to kill with a thought. With that in mind, I suggest the following categorization... god - a pyrokinetic who can only kill one enemy warrior at a time God - a pyrokinetic who can kill an enemy squad at once Oh God! - a pyrokinetic who can kill whole armies with an angry glance [Answer] To set the mood for this answer, we should all remember how this works. [Clear your mind, and will the paper to burst into flames](https://www.youtube.com/watch?v=bkNPcl7t2Zw). Now, let's start with two assumptions: * Your world doesn't have access to thermometers, much less any more precise technologies. * You're looking to create a "hierarchy within a guild," meaning a means of comparing one practitioner to another ... not necessarily a way to say "that guy can produce 2,000 joules/second!"1 Under these assumptions your easiest solution is for your well-developed, respected, and ancient guild to have selected a half-dozen materials with specific quantities. Let's say (somewhat arbitrarily)... * a 1/2 cubic ft block of aspen wood (how long to burn to ash), * a gallon of water (how long to bring to boil), * an ounce ingot of copper (how long to melt), * a 1# ingot of steel (how long to melt), * A 5# block of glass (how long to melt), * a 10# block of obsidian (how long to melt). The effort, because there are sub-achievements (like cracking the glass, warming the obsidian, etc.) would provide a basic gradation of skill and power. An initiate might be able to get the wood to burn, the water to steam, and the copper warm. An archmaster might be able to vaporize everything in under an hour. This method is imprecise, especially since weather is a factor. The job is simpler (if only fractionally) when done on a hot summer day than the dead of winter. But, it would create a viable pecking order.2 So, let's change our assumptions: * Your world has access to thermometers and stopwatches. * Practitioners carry around government-mandated identity cards that list the statistical capabilities of the practitioner somewhat like a passport. Under these assumptions your solution isn't much different, but demands fewer materials. Probably just one. Let's say the goal is to see how much the practitioner can raise the temperature of a sphere of [Inconel](https://en.wikipedia.org/wiki/Inconel) with a radius of 0.5m having a mass of approximately 4.3kg in 20 seconds. What we're looking for is the measure of ℃/s. This measure (℃/s) has, of course, become known as the Naidoo after the creator of the measure for pyrokinetic purposes, practitioner Iminathi Naidoo. The Naidoo reflects the potential of the practitioner to heat or combust anything. The ability to raise the Inconel sphere 20℃ in 20 seconds means your Naidoo rating is 1. But, what does this mean? I'm glad you asked! The "Naidoo Combustibility Index" or NCI (the measure of how many Naidoo are required to "spontaneously combust" or bring a material to flame in one second or less) was developed and referenced by practitioner Naidoo in the NCI Reference Guide. Look at it this way. The thermal conductivity of Inconel is (basically, there are a lot of kinds of Inconel) [73 kW/m℃](https://link.springer.com/article/10.1007/BF00503645). That of copy paper is [0.33 kW/m℃](https://www.researchgate.net/publication/254334214_Thermal_Properties_of_Copy_Paper_Sheets). This means you need 221 times the Naidoo rating to heat paper as fast as you heated Inconel.3 But, the NCI is a measure of spontaneous combustion. Paper's [autoignition temperature](https://en.wikipedia.org/wiki/Autoignition_temperature) is between 218℃ and 246℃ (call it 230℃ for fun). With a room temperature of 25℃, we need to lift the temperature 205℃ in one second or less. Thus, the NCI rating of copy paper is 221 \* 205 = 45,305 (let's call it 45,000 Naidoo or 45kN4). Now, if you can't spontaneously combust a piece of paper, then you have no business joining the Pyrokinesis User's Guild (PUG), minimum of 45kN to join.5 --- 1 Not to be confused with Watts, right? 2 "You mean you couldn't melt the copper? Hahahahahaha!" 3 Oh, I'm simplifying this process something awful, but I'm having fun doing it. 4 Anyone thinking that N means "newtons" is being way too serious about this.... 5 And I am having way too much fun putting the "fiction" back into "science fiction." [Answer] I've definitely been in your shoes. It turns out the question you're trying to answer is an inexorably difficult one, but there is a couple ways we can approach it with simple formulas.. Why is it difficult? As you already mentioned, heat transfer is complicated. It involves conduction, forced and free convection and thermal radiation all applying in 3 dimensions with complex surfaces and an enormous range of non-constant material properties. It's a mess except in the most simple of cases. Here let's look at 2 simple cases: heating something fast enough that it doesn't have time to lose heat to the surroundings, and splatting heat just onto the surface of a thing like a laser would. Here if your mages are trying to ignite something, they're trying to focus enough heat into a small enough space. Only one point needs to become hot enough to ignite (250C-ish) and the rest will burn from there. Despite having much less energy, a tiny spark is better at igniting things than an oven. The necessary temperature to ignite something is called the autoignition temperature, and can often be found through google searches. So your mages should be able to apply a certain amount of heating power into a certain volume (smaller = better) over a given length of time. Let's look at some first order equations to help shape our understanding. Here let's assume they're applying heat in a cylinder shape with a diameter+length we determine because it's a nice shape for the focus of a magic heat-beam and convenient mathematically. Also, your mage would need to hold their heat-beam steady for the duration of the time, or the heat would spread out too much. Heating the Inside Time to Ignition = (Autoignition Temp - Room Temp) \* (Specific Heat \* Density \* (pi/4) \* diameter^2 \* length) / Power(magic) units conventionally in C, cm, g, J and W. Let's look at igniting paper: Time to Ignition = (230C - 30 C) \* (1.34 J/gK \* 0.8 g/cm^3 \* (3.14/4) \* 1cm^2 \* 2cm) / 500W = 1.3s The actual length of time is easily tuneable by making the mages more powerful, or focusing their beams tighter or broader. To me, 1.3s sounds like a nice amount of time to make a character wonder if it's working or not. As a reference, 500W can heat a cup of coffee to boiling in a few minutes. Microwaves are often 1000W. Also, this formula completely ignores heat conducting away, which is fair enough for these power levels and the accuracy we're aiming for. An alternative, and the last stop on the trip to way too much information, is heating the material at its surface rather than in the body. This approach would require less power but be more complicated. Heating the Surface Time to Ignition = ((Autoignition Temp - Room Temp) \* Thermal Conductivity \* diameter^2 / Power(magic) )^2 \* (pi/4)^3 / Thermal Diffusivity units this time traditionally in W, m, K, s. Example for wood: Time to Ignition = ((230C - 30C) \* 1.26 W/mK \* .01^2 m^2 / 5W)^2 \* (3.14/4)^3 / (1.1\10^-5m^2/s) = 1.1s Notice in this analysis the pyromancer is 100 times less powerful than before (Now 5W), but still able to heat things enough to burn, like a high power laser pointer. That's because we're not heating a large volume, just the surface. This formula is much more prone to inaccuracy though, as it doesn't account for convection or multidimensional heat flow. I'd probably multiply it by 5 or 10 in practice*, and don't trust any times over a couple seconds from this equation. I hope that helps. Best of luck with your world! [Answer] What you are looking for is a bomb calorimeter. Instead of providing a known ignition source (spark) to an unknown material sample, you provide a material samples of known combustibility, and have your fire bender ignite the contents of the bomb. Measure the temperature change compared to the temperature change for the known ignition source. There is likely to be more than raw ignition power involved in measuring the total ability of your mages. Distance, precision, sustainability over time, spark rise time, etc are all factors that will come into play for determining where each Mahe would be most effective. [Answer] Pre thermometer world: One simple test would be the time it takes to make a small bowl of water start to steam. This is dependent on temperature and humidity. For timing either a count the swings of a pendulum, or use a water clock. Another test is to ignite a ball of dandelion fluff. This requires less power, but greater focus. Such a power may be expressed in different ways. Consider: If I can deliver a kW to a cup of water that is very different from being able to deliver the same power to a cubic millimetre. The latter has a power density 250 thousand times as great. On the other hand, suppose that you had a practicianer that could move gigajoules from 1 cubic kilometre of air to another. The power density is low. The power level is high. This lad would be rejected by the guild because he couldn't make a cup of water even warm, but he can herd clouds, and make rain -- maybe. Consider how long they can work. One mage may be able to boil that cup of water in to steam. Another may be able to run a slow cooker all day. Same energy, different power rate. Consider one practicianer who has to see his target, and can only heat while looking at it, another who can heat anything he has seen or knows well, a third who can work by holding an artefact that was once in intimate contact with the target (law of contagion) Some might be able to see something and move their focus inward -- the brain cooker mentioned in another answer. (Personally I think that cooking their eyeballs would be both easier and more effective.) A person who had a small cloud herding gift, but had great stamina could power his own hot air balloon. Someone who had great focus and power would make an awesome black smith's assistant. Someone who didn't need to see his target may be able to cauterize internal bleeding. (Requires some form of clairvoyance or seeing around corners.) You could have fun with different orders that have regimes for training different aspects of this skill. [Answer] You would also need to consider the range of the ability in addition to the other answers (ie. energy and power). A pyrokinetic that can set something on fire from a range of only 1 meter is far less dangerous then someone who can do the same thing at a range of 100 meters or even more. Most likely the ability becomes weaker over a longer distance so you would need two tests: 1. Performing a simple task everyone can do, say ignite a match, from a set distance. Keep repeating the test at increasing distances until the participant can no longer ignite the match. 2. Measure the person's energy and power as per the other answers but at a set reference distance. [Answer] Hmm, it might be useful to imagine magic as some sort of catalytic effect; rather than dumping energy into things to make them burn, you just reduce the normal activation energy for oxidation of combustibles they carry on them (or on their enemies). That might make it a lot more feasible, or else your pyromancers will be bingeing at the spaghetti warehouse before every battle. [Answer] What if instead of transferring heat over a distance, which in itself would mean that energy losses would occur, you could instead add [kinetic energy](http://www.physicsclassroom.com/class/thermalP/Lesson-1/What-is-Heat) (I mean, they are called pyroKINETICs) to the particles of the matter that you're trying to burn? It's more handwavy to explain how the energy got there, but it is still believable as long as it's magic. (for instance, since you said the pyrokinetics believe their power comes from the sun, you could visualize this effect by having a magical ray of sunlight cast down on the object, even in closed spaces, that would begin to accelerate the movement of particles in that spot.) As to how to measure it, it would be simply how fast you'd reach your intended heat level: have something burst into flames, boil, melt etc. I believe this would fit with your idea of pyrokinetics since it would be impossible to create flashy floating fireballs, but would be very believable to boil the air around a target or burn the target's skin, perhaps even internal organs if your handwaving would allow that. [Answer] Great answers on measuring energy and power of a fire blast. What about a different scale, inspired by "Worm": # How dangerous? Rank your espers in the way how fast, how bad, and how many people are needed to subdue their powers. It is an indirect scale, generating one small superhot fire ball and generating a slightly larger but much cooler fire ball might differ a lot in terms of energy, but little in terms of damage (if both are hot enough they both are fourth degree burns anyway). ]
[Question] [ Let us say that the siege [here](https://worldbuilding.stackexchange.com/questions/4188/what-would-be-the-problems-during-this-type-of-siege) was 100 percent successful. One of the answers pointed out that even if it did, the country wouldn't just ... die. So we need a reason why, excluding: * Religious reasons. In this part of the world where the war is, the religion is uniform. * God-king or the like. The country is a type of constitutional republic, while still with lots of absolutism elements My thoughts so far have been: * Loss of an important trade center. If let's say, mercantilist politics are what keeps the country alive, the fall of the biggest trade center might be devastating, and the resistance would fall in a couple of weeks. * Internal power struggles. Let's say that the emperor/king was in the city, and captured. Power struggles for what is left might make the country fall quickly. What other reasons could there be? PS The economical and technological level is late-medieval/renaissance, the city populates are 50% educated, while only 10% in villages. Still the news can be spread quite quickly, the fall would be known to everyone in a matter of days. [Answer] Historically, collapse because of the loss of a capital (and for that matter, the existence of a capital) was an outgrowth of the concentration of power in an absolute monarchy. In Europe, for most of the medieval period, a country's government was highly decentralized. Most of the decisions, record-keeping, and similar matters were done at the most local level possible, by the relevant noble. The closest thing to a "capital" was "the castle the king is currently residing in", or maybe "the city that the council of nobles traditionally meets in". Capturing the king might cause a collapse (though probably not -- remember, decentralization means the nobles can keep things running just fine, and the presence of an invading army provides a focal point to keep them from fighting each other); capturing a bunch of buildings, not so much. As power became centralized, so did the bureaucracy of government; various other things such as finance and industry tended to follow this centralization. By the 1700s, taking an enemy capital meant capturing the people responsible for making decisions, as well as those responsible for the day-to-day operations of government, most of the country's financial infrastructure, and possibly much of its industry. So, in answer to your question, how centralized is your country? Rapid collapse from the loss of a capital comes directly from loss of warfighting ability: if you can't pay the army, or can't keep it supplied with food, it's going to fall apart in short order. On the other hand, if the troops are paid by their ruling lord (who is probably also their commander), and are supplied by living off the land, loss of the capital can be merely a minor problem. [Answer] In medieval times, the power structure was largely built on the basis of a protection racket. "I'll let you live on my land in exchange for taxes. Don't like it? I'll just as happily toss you off my land. What, it's your land? My sword arm disagrees." The serfs were protected by the land-lord, who was protected by the duke, who was... until you got up to the king. That whole house of cards is predicated on the belief that your liege can actually provide the protection they promise. If the king can't even protect their own seat of power, it casts that belief in quite a bit of doubt. [Answer] Lengthy explications about national morale and politics are applying modern thinking to a pre-modern situation. If you're a medieval peasant, the king is a remote figure. He doesn't necessarily speak the same language as you. He certainly doesn't care if you are happy or unhappy, as long as you pay your taxes and don't cause trouble. If the king is replaced by another king, so what? Assuming the new ruler doesn't indulge in religious persecution, ruinous taxes, or wanton destruction, you will carry on as before. You're too busy trying to get the harvest in to worry about politics. If a kingdom is large and decentralised enough to have autonomous local elites, they may well fight to protect their own privileges. For example, the Normans "conquered" England in 1066 but faced major rebellions in the north and east for several years afterwards. Conversely, if a state is highly centralised, and the capital falls to an external invader, there is nobody left with the motive or capability to organise resistance. The king and his court are dead or exiled. Most of the royal bureaucrats are willing to serve the conqueror as they served his predecessor. In this case, there tends to be a fairly smooth assumption of power by the new rulers. The sort of model you're looking for is a change of dynasty in medieval China or ancient Egypt. The replacement of the Ming by the [Manchu](http://en.wikipedia.org/wiki/Qing_dynasty#Formation_of_the_Manchu_state) in China is a good example. [Answer] Your country is probably a constitutional monarchy like the UK except that the king has more power in your case. In this case, it is possible to relocate the parliament. If the king dies, it might be problematic but with a parliament, it's less likely to see the country fall into a civil war. Other elections can be held, someone else in the parliament that was not captured could hold the reigns until the election... Unless every elected official and everyone with political powers is now a prisoner. Then, since no one is a position to decide it would require the involvement of the civilians to decide what to do next. The army could seize power temporarily, just long enough to restore order. This require the population and the army to share strong democratic and republican values (not the US parties). If they don't believe in democracy, they won't restore the Republic as it was before. Capturing the capital could ruin the economy or not depending on the size on the country. If you have other trade centres, the economy might not collapse but there will be difficult times ahead. Lack of military coordination: The main problem is that the enemy was able to capture the capital quickly. This is a serious issue because the capital is supposed to be well defended and far from the dangerous frontier (usually). This might cause some serious panic and is making a counter offensive more difficult. The rest of the country might not be able to organize a counter offensive at all. If the other army was able to move so quickly, they might be able to do it again and no city is really safe. What about the military strategists/generals, are they still alive? Those still alive will have tough decisions to make to secure the country. It becomes harder to communicate information and harder for people to move inside the country. Information travel more quickly than an army but it's not enough to prevent a complete collapse. Gathering an army large enough to confront the enemy might be a near impossible task. The time required to gather an army and the time required to coordinate an attack is something to keep in mind. See this example: * In 732, the Arabs started invading the Frankish kingdom. The Franks were able to stop them only in Poitiers. This is really far from the frontier and if the Franks had lost the battle, they would not have been able to gather another army. Sure, some lords would have resisted but most of the country would have fallen into the hands of the Arabs. I think your country would be in that situation. [Answer] From a historical POV: * The capital is the center. The king lives here, and probably most of the nascent bureaucracy, together with the church principals. Except for nobles (which during feudalism live in their own possessions), you have got most of the resorts of power. * The capital is big, economically and in size. Probably the king chose in the first place a town that was already important in its own (due to size, communications, trade route) so he could defend it easily (no sense in living a month of travel away from your principal base of power). After it became the capital, that importance was increased due to business brought by the court. You have lost an important source of income and recruits. * The capital is fortified. Since warfare is usual, when chosing the location it has been important for it to be a relatively easy to defend position. Maybe not an eagle's nest fortress (how would you feed the people then?), but definitely somewhere with access to water (to resist sieges), good walls, etc. In fact, if it did not have that, probably the town would not have become important enough to be chosen seat of government. Of course, after the king settles in, he has personal interest in improving the defenses. * War is already lost. From the previous points, it is clear that the defending forces should try a serious attempt at defending the capital city (the exception would be if the city if taken with treachery or a coup de main). So, either the defender could not raise an army big enough and had to flee, or a major battle was fought and lost before losing the city. The fall of the capital is not the reason of the defeat in the war, it is just the sign that the enemy cannot be resisted. To me, this would be the most important aspect. * War is lost, so what? Usually most wars do not imply annexation/anhilation(\) of the enemy. The invading nation was asking for some counties to which its sovereign claims he has right to, after the defeat is clear (due to previous point), surrendering is the lesser evil. You cede those territories, pay an indemnity, and wait until you can hit back at your enemy. Keeping the war going while the enemy army has your capital means your fields and palaces are sacked, the harvest is lost or robbed by the enemy and your people suffers famine. (\) Even in the case that the invading army means to conquer the country, usually that means only removing the upper echelons. Once it is clear the war is lost, if the king does not agree to peace talks, then a string of defections will begin, with nobles ackowledging the new king in exchange of no territorial losses in their domains. It is in the king's own interest to offer peace while he still has something to bargain with. On the other hand, I do not think that holding the king prisoner makes much of a difference. If the nobles want to keep fighting, they can just hold a Diet or parliament, chose a regent and continue. And, at the opposite, if they chose to rebel they do not need to wait for the war to be lost. The do not need to convince their serfs; the serfs will do what their direct lord tells them to do, as they have no relationship/loyalty to the king (unless he happens to be their feudal lord). Also note, a 50% of educated people (even if only in cities) is a HUGE overrepresentation. Check for literacy rates in the XIX centuries. Check with the fact that, in modern England (s.XVI-XVII), a way to certify that you were a priest was [showing that you knew to read](http://en.wikipedia.org/wiki/Benefit_of_clergy) [Answer] If you are looking for reasons why the capture of a capital city might result in the total collapse of a nation, I would suggest arrogance. 1. The God-Emperor is a bit out of touch with reality. He cannot stand the thought that he might have to relocate from his palace temple. He orders his generals to defend the city "to the last drop of blood". After all "almighty Throg, whose city this is, will surely defend it". He proclaims this decision to the people. 2. Because of this, any member of the government, priesthood etc. (including generals) who leaves the city is considered a heretic and traitor. And since being a heretic and traitor carries the death penalty without the inconvenience of a trial, nobody in any kind of official capacity leaves 3. Therefore, when the city falls, pretty much everyone who is anyone will be captured. That would be enough to shatter any normal nation, and with a highly centralized government (which, surprise, the God-Emperor favours), certainly reason for collapse. This works just as well with the Emperor of All Known Space, with minor modifications. [Answer] There's a lot of factors here...the losing nation has 1 army, or several? The power now falls in the hands of the generals, and it's really their personalities and positions that determine the course of action. They will be forced to quick action however, the economic importance of the capitol likely means the army can no longer be financially supported, so sitting around waiting to be financially strangled is a poor option. There will also be a factor of how 'beneficial' the new rule is perceived...a general who views himself as dead under the new rule will likely take extreme steps, while one that feels a friendly reception from the new conquerors might be less inclined to enter a fight to the death and accept the new rulers. In either case, the outcome will be relatively quick simply because the generals can't support their army and will know it. 1. If the remaining military is one large force and the general in charge is decently loyal to the former kings cause (or ambitious enough that he wants to become king) I can see a rapid assault on the now captured city, hoping to catch the defences still down or otherwise unprepared to defend. Might be one of those cases where the population of the city can rise up and defeat their new oppressors in a similar move as to what just captured the city. Failure to re-capture the capitol is likely the demise of this nation Just an edit in - Unless the previous governing was horrid, the cities population is going to resist new rule. A city that 1000 elite troops can hide in is quite the population and there is no guarantee that the local populace (I assume atleast 20'000 people if 1000 are to enter unnoticed) won't readily join in an assault designed at freeing them from their conquerors)...even if they are better equipped, a small amount of soldiers attempting to subdue a much greater number on civilians while trying to resist a prolonged siege is not in a happy place. That said, the king/monarch deposed and the gov't brought to it's knees may still have the effect you are looking for. 2. 'Balkanization'...might not be the appropriate term, but with many generals and a spread out power base (IE no hope of recapturing the capitol) may see the individual generals each vie for their own power/wealth either seeking their own power (and failing in the face of the conquering nation), becoming loyal to the new throne/ruler, or becoming a mercenary group forsaking their former lands. 3. Assassins. Kill the remaining generals and who is left to rule? 4. Bribes. Same as above, but instead of killing them, offer them something to make them want to be a part of the new regime...money and/or power works. A soldiers loyalty is most often to his general (take Caesar and his assault on Rome, soldiers were loyal to Caesar and their general)...were the general goes, they go. 5. Ambition. This may follow the free french vs vichy french lines...a general in a relatively low rank, or an ambitious one that see's a greater position within the conquering nations ranks, can very readily drop their former loyalties for the opportunity for a greater future for themselves. Sometimes you don't need bribes, just their amibtion. [Answer] Consider road and canal networks. If the transportation was centered on the capital and there are few cross connections, the invader now has inner lines and the ability to defeat the remaining resistance in detail. While the examples are more modern, consider the defeat of the Whites in the Russian civil war and the siege of Paris in the Franco-Prussian War. [Answer] What kind of capital are we talking about? Is it a be-all-and-end-all of society, like Rome? Or is it a religious center, like Jerusalem? Or is it a primarily political place, and is most pointedly NOT the financial capital of that society, like Washington D.C.? The answer really depends on how important the capital is to the daily life and the continuous operation of a state. During the [Paraguayan War](https://en.wikipedia.org/wiki/Paraguayan_War), the "capital" was constantly on the move, as the state leaders and bureaucrats carried documents wherever the battle wasn't. Even though Paraguay was completely hopeless throughout the war against the much larger and more powerful alliance of Argentina, Brazil, and Uruguay, they didn't give up fighting even as the situation had long turned from worse to terrible. Another thing to consider: if a political capital is geographically and culturally distinct from a financial capital, the capture of the financial capital would do great damage to the defending state's ability to raise money for armies and to pay its debts. The financial elites may even find it beneficial to switch allegiances (if they are not slaughtered en masse, as the Mongols often did). So, for example (in a pre-digital age lacking instantaneous money transfer and an economic system rooted in gold) the decisive capture of New York could be fatal to the Union, without physically threatening Washington D.C. Heck, New York isn't even the capital of its own state, and, saying this as an upstate New Yorker, it is clear as day that New York City is more important to the function and morale of the United States of America than all of the rest of the cities in New York State, combined. ]
[Question] [ Suppose you open a portal between Earth and space with a diameter of 1 ft. The portal is an opening in space that immediately connects both sides, i.e., it’s like a [Portal](https://en.wikipedia.org/wiki/Portal_(video_game)) portal. How strong would the air be rushing in, and how much would it effect the area around it? Let's say the portal is 1 foot in diameter. [Answer] Using <https://www.fujikin.co.jp/en/support/calculator/>, I get a flow rate of $85,000 m^3/h$. This corresponds to $327 m/s$ through the hole, or slightly less than the speed of sound. However, at a distance of $1 m$ ($3ft$), the air would move at a speed of around $4 m/s$ ($10 mph$), and as you get further away, the air's speed will quickly decrease. All in all, anything within around $20 cm$ ($8 in$) will experience hurricane strength winds, but anything much further than that will remain relatively unaffected. My inputs were "flow rate" for calculation type, "gas" for fluid type, 1 for specific gravity (compared to air), 3500 for $c\_v$, inlet pressure of 101kpa and outlet pressure of 0. $c\_v$ is a number that describes the ease at which fluid flows through the valve. It is dependent on the diameter of the hole, the shape of the hole, and any other properties of the hole that influence flow rate. Also, [here](https://www.tlv.com/global/US/calculator/air-flow-rate-through-orifice.html) is another source that gives the approximately same answer. It makes reasonable physical sense that air will exit the portal at about the speed of sound. Here are [two](https://physics.stackexchange.com/questions/122993/do-airlocks-in-space-decompress-violently-as-they-do-in-movies) [sources](http://www.geoffreylandis.com/higgins.html) that say that air will enter a vacuum at approximately the speed of sound. Note: This differs from Willk's answer because that calculator assumes the fluid is water. [Answer] I used this tool. <https://www.copely.com/tools/flow-rate-calculator/> Starting values 304 mm (~1 foot) pipe, 1 bar pressure (atmospheric pressure), 0.1 meter hose. I got 50246 liters/minute. Velocity was for some reason in imperial and was 37.8 feet / second which I converted to 25.7 miles per hour. A hair dryer makes wind at 40 mph. But this portal is 12 inches across so it would be easier to dry your whole head at once in the wind. The only problem is that it sucks instead of blows and if you are not paying attention after your shower you could get sucked up against the 12 mm hole and if you occlude the entire hole with your wet body you will get a serious hickey. Which is OK too! I am not going to judge. It is a new era and each of us needs to live our own truths. [Answer] I'll go partially against the other answers, because I'm going to claim the portal has zero length , as opposed to a piece of pipe that's 0.1 m long in one of the answers. Next, I'm going to claim that the portal "material" is frictionless, so there's no drag (not that drag coefficient has any meaning for a 2-Dimensional orifice) Now we are essentially in the known situation of a hole in the wall of a spaceship, or the ISS. This is discussed, among other places, in [space.StackExchange](https://space.stackexchange.com/questions/30501/how-could-the-2018-08-30-soyuz-ms-09-iss-leak-be-so-slow) EDIT: using the [calculator](http://www.efunda.com/formulae/fluids/calc_orifice_flowmeter.cfm#calc) referenced at that page, I get a flow rate of about 4600 l/s for our 30.5 cm diameter orifice at 1 atmosphere. Velocity is roughly 63 m/s, well subsonic so other nasty effects don't come into play. [Answer] The typical speed of air molecules is (not coincidentally) approximately the speed of sound, and precisely the fact that the molecules moving at this speed no longer encounter any obstacles when passing through the portal is what causes air flow in this "experiment". Hence the speed of the air flow will be some 300 m/s (at typical ground conditions, but varying with altitude, pressure, temperature). Multiply with the area of the portal to obtain the volume flow. [Answer] This scenario is quite similar to that in [To the World of Death?](https://worldbuilding.stackexchange.com/q/177711/75), though with significant differences in pressure. [Choked Flow](https://en.wikipedia.org/wiki/Choked_flow) is assumed to occur in dry air if the ratio of upstream to downstream pressure is >1.893. Since the downstream pressure is 0, this ratio's value is infinite. So, we are looking to calculate choked flow of air through a double-sided portal 1'/0.3m in diameter. So, the formula we need is: $\dot{m} = C\_d A \sqrt{\gamma \rho\_0 P\_0 ({2 \over {\gamma + 1}})^{{\gamma + 1} \over {\gamma -1}}}$ * $\dot{m}$ is the choked mass flow rate. * $C\_d$ is the discharge coefficient, which we assume to be 1.0, with the actual discharge rate being equal to the theoretical discharge rate. * A is the area of the portal. A 1 foot/30cm diameter circular portal has an area of ~0.07 $m^2$ * $\gamma$ is the [heat capacity ratio](https://en.m.wikipedia.org/wiki/Heat_capacity_ratio) of the gas, for air at ~20°C: 1.400 * $\rho\_0$ is the gas density: 1.225 $kg/m^3$ * $P\_0$ is the upstream pressure. 1.0 atmospheres, or 101.325 kilopascals (kPa), or 101325 $kg/{m/s^2}$. So, if we plug the numbers into the formula, we get: $\dot{m} = 1 × 0.07 m^2 × \sqrt{1.400 × 1.225 kg/m^3 × 101325 kg/{m/s^2} × ({2 \over {1.400 + 1}})^{{1.400 + 1} \over {1.400 -1}}}$ $\dot{m} = 17.6 kg/s$ Converting to volume, we get $17.6 kg/s /1.225 kg/m^3 = 14.4 m^3/s$ per side, for a total of $28.8 m^3/s$ for both sides of the double-sided portal. This means that air would be rushing into each side of the portal at a speed of $14.4 m^3/s / 0.07 m^2 = 206m/s$... i.e. at about 741kph. Now, like light, as the distance from the portal increases, the speed of the air would decrease proportional to the square of the distance. So, at a distance of 2× the portal's diameter (2'/60cm), the wind speed would be around 185 kph, at 3'/90cm, it would be around 82 kph, 46 kph at 4'/1.2m, 30 kph at 5'/1.5m, 21 kph at 6'/1.8m and so on. So, anyone or anything that got too close would be violently sucked in, and depending on its size, might variously find themselves in space, sliced into pieces on the edge of the portal (if it has one), or might block the portal and possibly suffer from a severe vacuum injury. However, the portal would be relatively harmless to humans at any range much over a metre, most birds would be safe at a distance of 1.5m, and really only a threat to insects out to a distance of a few metres. [Answer] It wouldn't flow at all Gravity is what keeps air on the surface of the planet. Opening a portal from a low gravity environment to a high gravity environment. The flow is from the low to the high not from high to low. Air would not rush through into outer space any more than if you had a long pipe running into outer space. If portals worked like such, you could create perpetual motion machines dropping water at the top of a mountain and generating energy as it run down hill until going through the portal again. ]
[Question] [ Tech level is early Rome, China, Ethiopia, etc. ~ first century BC. Unlike history, there's peace and cooperation among all the benign monarchies of the whole Earth. But it's hard to get daily communication from (now) peaceful Rome to (now) peaceful imperial China, for example, and back to Ethiopia. Horses are not fast enough, heck even the mighty camel is not to the emperor's satisfaction. What would be a faster and more efficient way to rapidly transfer regular (say "once-a-week") messages across vast land distances, given plenty of existing resources, 1BC tech level, a few decades of research beforehand, humankind cooperation, and our expertise as WorldBuilders? Note: Keep in mind, there's almost entirely "peace on Earth" among the 300 million or so global population, and since it's land-transport, I can omit the Americas, unless you have a clever solution to that, focusing on the "over land" portion. [Answer] A string of heliograph towers. Traditional [semaphore lines](https://en.wikipedia.org/wiki/Semaphore_line) are unfortunately out; while the construction of the towers is relatively low tech, they rely on the use of optical telescopes, which weren't invented until the early 17th century. While [heliographs](https://en.wikipedia.org/wiki/Heliograph) weren't invented & put into regular use until the late 19th century, the basic concept is very simple. Wikipedia claims a flash could be seen from 30 miles with the naked eye under ordinary conditions; max range was ~10 miles per inch of mirror diameter -- with a record of 183 miles done by mirrors of only 8 inches square! Wikipedia tells me that polished copper mirrors appeared 3000-4000 BCE, and bronze mirrors showed up ~2000 BC. Metal-coated mirrors showed up in the 1st century AD, which aligns with your time-frame. Their quality was likely inferior to those used in 19th century heliographs, so their size would have to be correspondingly increased -- but working from a max range of ~30mi visibility by the naked eye, it would be quite feasible to use mirrors even if the quality was an order of magnitude worse (~10mi per 10 inch diameter = > 30 inch mirror). The biggest issue would probably be building, maintaining, and staffing the towers, which would have to be spaced at regular intervals across all manner of terrain. Regular supply runs for particularly remote towers might prove an expensive challenge. Weather would also be an issue, probably forcing some towers to be built closer together in some regions due to poor visibility. Closer intervals means more towers -- which means more expense. Actual semaphore lines may have used rotating indicators, symbols made up of straight lines at mostly right angles, articulating arms, or a series of shutters. However, a heliograph is limited to two states -- "on" or "off". Interesting to consider would be how different types of languages (pictographic / logographic / phonographic) would constrain or aid the development of the symbols used to encode messages for transmission. Perhaps there would even be competing standards! [Answer] The Chinese actually used a system of [beacon towers](http://www.travelchinaguide.com/china_great_wall/construction/tower/) that predate your scenario. These were installed along the great wall, using fire by night and smoke by day. Actually the beacon tower system predates the great wall and were in use around 200 BC. The message communicated was very simple though. Basically the signal meant that invaders were approaching. Modulation and coding of the signal would be necessary to carry arbitrary messages. Any of the signal tower methods have some weaknesses, mainly expensive to build and man, the man on duty can fall asleep, etc. and fail in duty. Men can be attacked or bribed to render the system inoperative. For comparison the book of Exodus records that the children of Israel were guided by a pillar of fire / smoke for night / day usage. This is often dated 15th century BC (though there is disagreement). Even if the Exodus story is a fable, the account of using fire/smoke to guide was written centuries earlier than even the Chinese beacon towers. [Answer] Pigeon Express Messenger birds have been around for a long time, and can travel much faster than a man on horse. The Romans were good at roads, and with peace comes trading, so it would be in everyone's best interest to establish a good route with inns every 30-40 miles. These would also be great places to house messenger birds, so a message could be written in Rome and sent down the line from bird to bird until it got to the emperor of China. Edit: While kind of a joke, there is a protocol for [IP over Avian Carrier](https://en.wikipedia.org/wiki/IP_over_Avian_Carriers#Other_avian_data_transfer_methods). In a race between a pigeon, a car, and Australia's Telestra internet provider, the pigeon transfered a 700 mb video file in 1 hour 5 minutes. The car took 2 hours 10 minutes, and the file upload was estimated to take 4 hours, but kept losing connection. While slower than light, their carrying capacity is pretty high, and things like maps, diagrams, mathematical calculations, pictures and other non alphanumeric items are much easier to transmit. > > With training, pigeons can carry up to 75 g (2.5 oz) on their backs. The German apothecary Julius Neubronner used carrier pigeons to deliver urgent medication. In 1977 a similar carrier pigeon service was set up for the transport of laboratory specimens between two English hospitals. > > > Pigeons can transmit data on overcast days, and even during the night. They can also be used in parallel, so that larger messages can be carried between multiple birds, and important messages can be sent via more than one bird at a time to reduce the chance total packet loss. [Pigeons can travel between 600 and 700 miles in a single day](http://www.pigeoncontrolresourcecentre.org/html/about-pigeons.html), meaning the 5000 mile distance between Rome and Beijing could be traveled in as few as 9 days with only 9 birds. Pigeons also have an advantage to ground based transportation in that they don't have to worry about terrain. This is much better than a horse, which as an average galloping speed of 25 miles per hour, and will be slowed by things like swamps, rivers, oceans, mountains, etc. > > Most people assume the Pony Express riders galloped their entire route. In fact, the speed of a pony express rider averages out to 10 miles per hour- meaning they spent most of their time alternating between a trot (about 8-9 mph) and a canter (12-13mph). The Pony Express riders switched to fresh horses every 10-15 miles. > > > Americas By using a route through northern UK, Iceland, Greenland and northern Canada, it is possible to use carrier birds to send messages into the Americas too. A China, Siberia, Alaska route would also work with a lot less ocean to cross. [Answer] One option that was not covered is using musical instruments. Historically this has only been used in situations where the line of sight is obstructed, market places, forests, and mountains, which is not directly applicable to your case. But since humans are already capable of audio communication it could feasibly support larger bandwidth, something close to speaking slow and careful. Instruments used historically have been horns, [drums](https://en.wikipedia.org/wiki/Drums_in_communication), and gongs. But I think for an infrastructure project like this you could go for something more expensive. [Hydraulis or water organ](https://en.wikipedia.org/wiki/Water_organ) was known early enough and while it was large and expensive, it needs a water reservoir, that might not be an issue for a permanent communications line. The main benefit is that it produces actual music which can be used to to encode messages fairly efficiently and user friendly. The main difficulty is obviously the resources needed to build an entire infrastructure of water reservoirs and water organs. But realistically all attempts to build a a communications network this wide would have similar issues. And the ancients had good enough practical understanding of acoustics to focus the sound produced in the right direction and a hydraulis could in theory scale to produce lots of sound, so the distance between stations could fairly large in comparison to other methods. And the need for water is somewhat balanced by not needing line of sight unlike the visual methods. [Answer] Tins can and strings. Ok, this is not really a serious recommendation in the sense that I would recommend it, but [Tin Can Telephones](https://en.wikipedia.org/wiki/Tin_can_telephone) were actually a commercial product in the US at one time. After a number of patented improvments, they were used at a range up to about 1/2 of a mile. Unlike semaphore towers, they could be used in heavy fog, etc. A half mile range is clearly a problem for a serious long-distance communication network though. Tin cans are in short supply in 1 BC too. --- [The Hydraulic Telegraph](https://en.wikipedia.org/wiki/Hydraulic_telegraph#Greek_hydraulic_semaphore_system) I don't remember where I read about this years ago, but I remember thinking it was pretty inventive. Limited to pre-defined messages and fairly expensive to build, but it was actually used in military situations in 4th century BC. I was foolish for not mentioning this originally, but the historical example for given for sending a message is between Sicily and Carthage. These cities (or just the island and the city) are hundreds of km apart and includes a considerable distance of the Mediterranean Sea. So, I don't know whether this reference is mythical, confused, or very impressive ancient engineering. [Answer] Okay, we didn't solve this problem until the telegraph, so it's hard. Gary Walker mentioned the Water Telegraph (which I was trying to invent in my answer) but I don't think the materials could convey pressure reliably over huge distances. While commenting on that I came up with another way... How about a small pipe full of standing water with a long wood "Stick" running down the middle? You couldn't move it fast, but you could move it quite a distance, say 10 feet just to pick a random number. If every 2 inches you calibrated a mark on the side of the pipe, each mark would mean a message, that would give you a vocabulary of 120 messages. In order to send a message you have some person apply steady pressure to the end of the stick until it reaches the correct position. The water would make pushing the stick slow but it shouldn't take too much pressure---perhaps you could use a ratcheted lever to push the stick so it could push fairly hard and keep the pressure on for a long time. It might even take days, but as long as the stick didn't buckle in the middle it should move--Very Slowly. A waterproof rope that floats might work as well, you would pull instead of push. Anything but a liquid seemed like it would have too much friction--with water it's more about overcoming inertia than friction so a steady pressure could work. If necessary it could be relayed at certain distances. Relays would be absolutely necessary to change elevation--this thing would have to be completely flat. To relay messages up and down mountains, a rope and pulley system should be able to go a good vertical distance and could be calibrated with the same message marks. ]
[Question] [ Within my setting, there will be a race of spider people, and they will have the ability to create "metal silk", which is basically taking any type of metal, realistic and fantastic, and dissolving it in silk. The result is a cloth that is soft, supple and flexible as silk, but as strong as the metal used to make the metal silk. What kinds of armor or clothing could they then be able to create, and would they be very effective? To explain more about how the metal cloth would be like, if you were to take a piece of the steel cloth and stretch it taunt over a target, then proceeded to slash or thrust at it with a iron sword, the sword would be unable to cut through the cloth. Although, if you upgrade the sword to steel, it will still be unable to cut through the cloth, but a thrust may pierce through. One obvious problem I can see with this metal cloth would be that even if weapons would fail to cut you, you would still receive a whole bunch of bruises. As such, any armor would then need to try and be [hammer-resistant](https://worldbuilding.stackexchange.com/questions/9117/hammer-proof-armor) to be effective, altough unlike in Feaurie's setting, these people, who are not giant, and are in fact of a slightly smaller frame than humans, will be more worried about much simpler maces, hammers and swords rather than war golems My go to solution at the moment is the [Gambeson](http://en.wikipedia.org/wiki/Gambeson), made of the metal silk, and possibly padded with more metal silk. I am also toying with the idea of how well a metal silk [Hijab](http://en.wikipedia.org/wiki/Hijab) and face veil would work. Notes on the setting * Late Medieval-ish tech levels. * There will be reasonable amounts of magic * Armor and clothing for both wartime and peacetime scenarios * They will be fighting each other, other humans, and possibly other races of [varying sizes](https://worldbuilding.stackexchange.com/questions/9507/what-should-architecture-of-an-imperial-capital-be-like-in-order-to-accommodate) * They will also be allied with some humans and those other races. * This metal silk is fairly common among the spider people, but much rarer among the humans and other races, although rich humans can afford to get this metal silk as well EDIT 1: The armor need not be COMPLETELY made from the metal silk, they could wear plate, and have extra cloth over it [Answer] It could actually be less effective than you think. Consider chainmaille, which is similar in nature, but heavier. It has a few weaknesses, but it forms a real-life basis to compare against. Against bladed weapons, I would layer metalsilk with some padding cloth. A single layer of metalsilk would not really stop a blade very well. The cloth would simply fold around the blade and become a very thick blade. Given that the edges on many European swords were dull by today's cutlery standards, the silk would likely do little to nothing. However, layer many layers of metalsilk with interspersed layers of cloth, and you start creating something thick enough to provide defense. Piercing would go straight through a layer of metalsilk like it isn't there. All woven fabrics (chainmaille included) are weak to piercing because you don't have to cut a fibre, you merely bend them around your blade. Defending against piercing would require many many many layers (think kevlar vest). More likely, you'd hybridize: put a layer of leather over your metalsilk/padded cloth sandwich. Leather is really good at handling these kinds of strikes. Bamboo is also popular for stopping arrows. As for crushing weapons, it would provide zero protection... nada. If you want protection from crushing weapons, you'll have to look elsewhere. The layers of cloth in your armor stack will have more effect than the metalsilk will. As Samuel mentioned, the real answer is to focus on fighting style. The big advantage to cloth is mobility. The oriental nations focused greatly on mobility, so consider patterning it after their armor rather than European armor. A metalsilk tunic under some bamboo armor (to stop arrows) would be a remarkable improvement over what the Japanese Samurai had. to work with. [Answer] Actually, I don't know why you't need metal silk. Regular silk is incredibly effective as body armor all by itself. Mongols and others have used silk as armor for a long time. Some of it was 30 layers thick. Tests prove that if Ferdinand had been wearing his [silk body armor vest](http://www.theguardian.com/artanddesign/2014/jul/29/bulletproof-silk-vest-prevent-first-world-war-royal-armouries) the assassination attempt on him would have failed. Silk is actually comparable to steel in many [respects](http://phys.org/news/2013-06-spider-silk-nature-stronger-steel.html), and it is much lighter, so while I think it's a cool idea to spin 'metal' cloth from spider silk, using regular silk would be just as good and likely weigh less. Of course with any fabric you still have crushing blows to deal with and while 30 layers of silk will provide some padding and protection, a direct blow from a mace is still deadly. but no armor is perfect protection from every weapon. [Answer] If you wanted to make your metasilk super effective, rather than simply making it impenetrable, give it a property that makes it highly conductive to force. Imagine that a spider has made a web, they need to feel every movement of a creature that is caught in or touching that web. Consequently the silk it is made from is designed to take any type of pressure on the silk and translate it into a message travelling along the silk to where the spider can read and interpret the feedback and choose whether or when to attack. Now if the silk was originally evolved for this purpose, fabric made from it might be exceptionally good at turning force received on the side of the fabric into force moving along its threads, effectively diverting the kinetic energy of impacts around the wearer. This may be more interesting than being purely impenetrable as it would make a brilliant under-layer to armour designed to stop slicing or penetrating attacks. As a side-benefit, wearing it would make training with blunt weapons far safer, so groups that had access to it would potentially be able to train harder at lower risk to themselves, allowing them to become better in battle. If it can convert transverse into longitudinal force, we might also expect it to be least effective against blows struck directly against the line of fabric, whereas glancing blows are easily absorbed. This would probably affect the design of armour created using it. Possibly it would need a certain amount of space around it in order to work correctly, due to the way it flexes on impact, so it would work better under other armour than over it. I imagine that maybe the experience of wearing it would be that when the wearer was struck, they would feel the blow but all of the fabric would vibrate as the energy passed around them. It might even have a distinctive sound when this happens. [Answer] There isn't much more you can do with cloth armor than what you've described already. If you're able, you'd want to get as close to plate armor styling as possible. The whole point of plate armor was to deflect blows. The [angled surfaces](http://en.wikipedia.org/wiki/Sloped_armour) will guide impacting force away from the wearer. Aside from that, which it seems you already knew, with cloth armor your main advantage is mobility. Your main focus should be on fighting style rather than armor style. Being nearly impenetrable (but not uncrushable) is like having a mithril shirt. You want to maximize glancing blows. I would imagine if you have any melee fighters, that they would be a rogue class, preferring quick weapons and sneaking. [Answer] From <https://en.wikipedia.org/wiki/Spider_silk> ... "Weight for weight, silk is stronger than steel, but not as strong as Kevlar. Silk is, however, tougher than either." For non-crushing classes of weapons, layers of organic silk can be equivalent or even superior to metals. Historically the Chinese and ancient Persians used silk armor extensively. [Answer] This concept sounds neat and would create cool visuals. However, having made and worn gambesons I have a few concerns. How do you sew it? Does the needle go between the woven strands or is it pressed out like aluminum foil? You might need some specialized needles to do the quilting. This metal silk sounds like it would hold in heat like a space blanket. Real silk keeps heat in as well. I think you might have to design in some ventilation. Gambesons need to be washed or they smell horrible. How do you wash a metal garment? Does it rust? [Answer] Your answer is yes. It would be extremely effective, if used properly. Let's compare it to [chainmail](https://www.youtube.com/watch?v=VtJS1MziI98). Since it has a similar principle. Chainmail is a decently good defense depending on the thickness and diameter of the rings. (Thicker rings = better, and smaller diameter = better). The strength of chainmail relies on preventing the blade from passing through the material, therefore stopping the cut. Good chainmail has been known to stop arrows. The type of piercing it is weak to, is bodkin arrows or thin knives that fit between the links. (which is why mail with smaller links is better). Unlike how Cort Ammon says it would be vulnerable to a thrust, it is not. Because a thrust to penetrate, it must penetrate. He mentioned that the metal links would fold around the blade and basically still cut you. This is simply not true. This is because the mail is not loose. It is going to be tight so then it wouldn't have enough give to fold around a blade like that. (and even if it did, it wouldn't actually cut you, it might break your ribs, but not actually cut you) Now it is true, that mail would be weak to bludgeoning. This is because one layer of material is not going to cushion the blow. Now let's see how your metal silk compares to this It would have the advantage over chainmail in that it would be finer and therefore not have a problem with bodkin arrows and thin knives. (or polearms with those thin spikes) But it would have the disadvantage of having thinner metal fibers, and those would be able to break more easily than chain links. And it would be useless against bludgeoning. But never fear. The purpose of chainmail is not to be used on its own. It is worn historically as either underneath plate or on top of gambeson. Gambeson, this is how it would be used. As either a protective layer on top of gambeson or literally make gambeson out of this material. In either situation, you wouldn't just use 1 layer. You would use multiple layers stacked on one another. And if you made a metal silk gambeson, then you would stack anywhere from 20-100 layers of metal silk depending on how good you wanted it to be. And the thicker it gets, the better it becomes for certain. What happens is as it gets thicker, a. the less you have to worry about the thickness of the metal fibers, and b. the more it will cushion against bludgeoning attacks. I would still recommend layering this in with, or on top of gambeson as normal cloth makes a more effective cushion. Another great way you could use this is brigandine. Brigandine is a layer of canvas or leather on top of metal plates with another canvass/leather layer underneath. Just swap out the canvass/leather with metal silk, and you have another alternative. But, this is all assuming the metal that would be used is steel. You said, "any metal" including fantastical metals. If you used a special metal, you could remove any, or all of the disadvantages of this material, and have the perfect armor. [Answer] Hmm, it really depends on the weapons its designed to stand up against. Against cutting and piercing weapons, it might be far more effective than many would thing. A padded gambeson made of layered linen was surprisingly protective against swords and arrows and lightweight, which is why it was a mainstay as armor for many. Not as effective as a good brigandine, jack of plate, or riveted chainmail, but still more effective than many think. And that's when made from linen, other cloth fibers and/or materials, like silk, could be even more effective. One of the things that many people often fail to take into account is the thickness of the armor matters. A single layer of kevlar, our closest equivalent to your metalsilk, isn't very protective. Even a kevlar vest has several layers to it, and often has pockets in it to allow for the insertion of steel plates in many modern ballistic designs to stop bullets, but the kevlar vest's primary role, in the military sense, wasn't in bullet proofing, but in protecting against shrapnel, which is far smaller and lighter than a bullet. In an environment with magic, you have something that even a couple of layers could provide some shrapnel protection, as many settings seem to like using mages as artillery. And you can't dismiss the protective qualities of silk armor, which also has a high tensile strength, and as some have said, a sufficiently thick armoring of silk can stop a handgun bullet rather easily by bleeding off its momentum. Against thrusting weapons, a good idea would be like a brigandine (riveted plates between separate layers) or a jack of plate (sewn in plates between layers) for close in work, but a sufficiently thick garment would be more effective against arrows than many think, so long as they're not fired from relatively close range, or have heads that are designed to punch, or cut through the armor. Even then, it would depend on the draw weight of the bow, and military bows had a draw weight that was far heavier than most sport bows in use today. Against a crossbow? Better to not get hit or have something to use as cover to hide behind. For resistance against weapons designed with inflicting blunt trauma in mind, that's a bit harder. Weapons like hammers and maces were highly effective against armor specifically because of their forward center of balance making them very effective at directing the force of their weight onto a single point without having to rely on the penetration power of a thrust. Making it so that a person wouldn't get hurt when being hit would require the armor to be either too thick to move easily in, or too heavy to move easily in, and armor wasn't designed to make it that someone couldn't be hurt, so much as it was designed to ensure that the person getting hit was more likely to survive or not take a lethal injury. Most armor designs are compromises, as they have to be strong enough to increase survivability and reducing the chance of taking a lethal injury, while still being light enough to move in. [Answer] Silk width metallic fibres aren't going to be that useful against heavy slashing weapons; they'll break individually, like if you ran a knife against the edge of a piece of taut cotton, so even a thick quilted jacket of many layers won't be that effective and anything less will be pointless as battle armour. Against blunt weapons like cudgels even a thick jacket that would stop the first couple of sword blows will be completely ineffective. Forthe same reason sword blows against this kind of armour, those that don't break through to cut the victim, are still going to break bones because the "steel silk" is far more flexible than plate or chainmail and will transfer, rather than dissipate, more of the energy of the blow than such armours. Heat buildup in a quilted jacket of silk would be even worse than in a suit of plate leading to rapid heat exhaustion and death (which can be a major problem when fighting in plate in hot weather anyway). Having said all of that this material is not at all useless or pointless, as a measure against an assassins knife or a poison dagger this material would have many of the characteristics of a light mail lining to normal formal clothing but be less cumbersome, more attractive, and more comfortable. Material quilted until stiff made entirely from such silk will still be lighter than a similar thickness of steel and much much quieter making it ideal for situations where stealth is paramount but protection in the case of failure is still important. I'd have a look at the special material guides for D&D and look at what they do with the magical silks they have in there for some ideas as to the relative role of such a material. ]
[Question] [ As one of the feature in my world, I want to create a very deep chasm, as deep as possible. If it can touch the core, it will be perfect. Size does not actually matters, although I think the consequence of having a very deep chasm would be a big size. Note that to qualify as chasm, it must be relatively narrow. Without being artificially created (although I think it's impossible to do it artificially), what are possible ways to create such chasm? There is abundance of magic in this world, but please no "earth bending" the ground. Causing an earthquake seems to be able to do that, however please briefly explain how the earthquake create the chasm and the feature of the chasm created (I believe the one created from tectonic movement will be different from volcanic one?) [Answer] The best way to make a chasm on land is the way nature does it- slowly, and with water. As AndreiROM points out, the rapid appearance of a chasm is going to displace a huge amount of rock, proportional to the size, and that's going to have even larger effects on the planet, and even magic won't change that. Additionally, as David Lago points out, there are fundamental limits on the height of structures in a gravitational environment. Check out [this site](https://talkingphysics.wordpress.com/2011/09/08/how-high-can-mountains-be/) for the math about how tall a mountain could be, and essentially reverse the logic to get maximum depth on Earth- about 10km. If you decrease the size of your planet, you can go even deeper and get something more like the [Valles Marineris](https://mars.jpl.nasa.gov/gallery/atlas/valles-marineris.html) on Mars, which isn't as narrow but is definitely huge. However, even canyons that have been carved by water are extraordinary- I'll let the picture speak for itself. [![The Grand Canyon](https://i.stack.imgur.com/nvmhT.jpg)](https://i.stack.imgur.com/nvmhT.jpg) The Grand Canyon is still tectonically active, but I believe it's stopped getting deeper because it's getting filled in more rapidly than it erodes, mostly due to humans removing the erosive water for use elsewhere. If this is chasm-like enough, you could argue that your planet simply allows for it to grow deeper. First, change the geology to be mostly [limestone](https://en.wikipedia.org/wiki/Redwall_Limestone) or [sandstone](https://en.wikipedia.org/wiki/Coconino_Sandstone), both of which have a high angle of repose, allowing them to form even steeper sides. Second, have the river drain from high mountain areas with consistent snowfall to ensure semi-constant erosion. With those qualifications, you could probably justify a chasm ~8km deep. If you're especially eager to have it happen overnight, you'd have to handwave a little bit. Maybe there's a massive internal lake blocked off by some kind of dam that collapses, allowing the water to flow out very rapidly. These are called [outburst floods](https://en.wikipedia.org/wiki/Outburst_flood) and they were relatively common during ice ages. This still wouldn't happen overnight and wouldn't produce something as steep as the Grand Canyon, but it'd be faster if that's what your plot requires. Honorable mentions The other thing I want to mention here are the chasms in the ocean. The smaller of the two are the [submarine canyons](https://en.wikipedia.org/wiki/Submarine_canyon), which could be exposed by a reduction in sea level as water is stored as ice in the poles during an ice age. Congo Canyon starts at a depth of just 26 meters, and could be further exposed from there. If you evaporate all the water off your planet, like what scientists currently believe happened on Mars, you'd be left with the subduction trenches. These are seen in the Heezen-Tharp map below at the northwest portion of the Pacific, along the Ring of Fire. [![enter image description here](https://i.stack.imgur.com/fKsHY.jpg)](https://i.stack.imgur.com/fKsHY.jpg) I believe these are the largest chasm-like structures in the solar system, so they might be what you're looking for. [Answer] A cataclysm that creates a chasm that reaches the core of the planet would be a world-ending event. However, deep chasms can form in somewhat milder ways as well. If it's only the end result that matters, and time is not really of the essence, this might be caused by shifting tectonic plates. The Mariana Trench, for example, exists partially due to tectonic plate movements (as well as other geological processes). If you want this thing to appear overnight, however, you're looking at an extinction level event such as a very sudden tectonic shift, caused perhaps by having the mantle rotate around the core of the planet. [Answer] In response to one of your comments: Rock begins to flow with aobut 7000 feet of overburden. Not fast. I witnessed this on a tour of the Bunker Hill Sullivan lead mine near Kellog Idaho. Throughout the lower levels, corridors were lined with chain link fence pinned with 1 foot bolts every couple of feet. The tunnels would gradually shrink from pressure, and chunks of rock would spall off, often traveling at high speed. In other tunnels, they would rebore the tunnel on a regular interval to keep it from shrinking to nothing. --- You can get bigger chasms with a lighter gravity. Less pressure. But lighter gravity means lower atmospheric pressure, and less ability to hold an atmosphere. So make the planet larger in diameter. This lowers the rate that gravity decreases with altitude. You can also get deeper chasms with tougher rocks. Granite, gneiss and basalt generally do better than sedimentary rocks. So your magic could be the remnant of a 'Make these lands stand until the sun grows cold and the stars grow dim' spell, so that they are harder than normal. This would have the side effect of slowing erosion. --- In Larry Niven's "Known Space" stories, Canyon was the result of the Kzin testing a Slaver weapon that suppressed the charge on the electron. Nuclear repulsion gouged a canyon a couple hundred miles long and several miles deep. Niven does not address rock flow. [Answer] It would need to be an unexplicable event since a hole deep to the core would never be possible, "Today, the Kola Superdeep Borehole is the deepest hole in the world. Only a few inches in diameter, it goes down 12km and took Russian scientists more than 20 years to drill. They stopped drilling when the temperatures and plasticity of the rock became too great to make further drilling viable." 12Km. Only that. From the surface at sea level to the earth core it lengths aprox 6300km, and within the 12km mark the temperature and pressure turned the job impossible to carry on. We didn't even scratch the surface. Let's say that the chasm was completely solidified already. It wouldn't work because the pressure of gravity would force the surroundings of the hole to the center, and the effect would be similar to what would happen if the surrounding areas were made of liquid. It would close in no time, and cause a HUGE earthquake that would kill every living thing on earth. Maybe a 12km chasm would make more sense. And yes, some earthquakes (million years ago) could have possibly done the job. [Answer] Rock isn't solid enough to form anything like that. If a chasm a mere 12 km across, 12 km deep and 100 km long formed, it would rapidly collapse as the near-liquid rock near the bottom (caused by immense heat and pressure that deep) would flow inward. Rock required to fill such a chasm would weigh on the order of 3E16 kg. That much rock moving 6 km vertically (on average) would generate 2E21 J, roughly the power of 10000 dinosaur killing asteroids hitting the planet all at once. I'm uncertain if life could survive that energetic an event. A chasm all the way to the core is right out. You may think rock is solid, but at planetary scales it is liquid, and we live on a thin layer of wet crust. [Answer] The African [Great Rift valley](https://infogalactic.com/info/Great_Rift_Valley) and the Red Sea are modern day examples of plate tectonics creating chasms in the earth as plates separate from each other. [![enter image description here](https://i.stack.imgur.com/P4ZqF.png)](https://i.stack.imgur.com/P4ZqF.png) pictoral description of the process As noted, there is a maximum depth which can be reached before the rock essentially flows like a liquid, but rift valleys would be the largest and most spectacular examples of chasms which could naturally occur on a planet. The other possible way to create a chasm would be a trench in a subduction zone, where plates are being forced together and one is riding over another. On Earth, these generally form under the oceans, but there is no real reason for this not to happen on land, assuming geological conditions are right. [![enter image description here](https://i.stack.imgur.com/gMR3l.jpg)](https://i.stack.imgur.com/gMR3l.jpg) Subduction zone, with a good view of the trench So large and deep natural chasms are formed by the actions of plate tectonics, and will obviously occur at or near where the edges of the plates meet. [Answer] Rapidly (geologically speaking at least) reverse the convection currents in your mantle, with opposing currents on each side of the future rift. The super-high plateau of granite that has built up over millennia will begin to be pulled apart, and due to its weakness in tension and a fault up the middle (internal plane of the crystal structure or some other discontinuity) will suddenly split in half. It might even crack all the way down to the mantle, though the very bottom would fill in quickly. No other world info to speculate on what causes the mantle reversal (aliens? near-miss with a sister planet? solar flares?) or the weakness through the center of the mountains (perhaps something religious, like an eons-old pilgrimage maintaining a line of offerings that weakened each new layer of rock). Whatever the cause, I would expect the change to have major cultural implications for several generations. [Answer] If you want a magical answer, I love the idea of a magical natural disaster for something like this. This is the only way to have a "believable" core reaching massive chasm. Of course, this will stray from a science based answer. For such a chasm to remain standing, there must be some property at the walls or in the interior of the chasm to allow it to remain. I am assuming you want this to have formed suddenly and people must be able to enter the chasm. This could be: * There are natural forcefields keeping the walls steady. Whatever formed the forcefields also blasted the matter into space. Magic would be needed to cross the field. * The chasm is full of an invisible form of matter and, while people far from the disaster sense that matter as intangible, the walls of the chasm interact with both types of matter. You would have to have a disaster which moves the chasm material out of "dimensional phase" (which is nonsense) with most of the planet. The walls are stretched between both dimensions (again nonsense handwavium) so interact strangely with both. * The walls of the chasm are frozen in time and, therefore, cannot be moved by natural forces. As you move towards the chasm, everything already there moves more slowly until you reach an event horizon where everything is frozen. Everything beyond that is just...gone. I like this as the result of a magical time travel paradox but those usually aren't natural. * There is a magical gravitational anomaly in the chasm. For some reason, matter near the central point acts much much heavier than normal but acts lighter as it moves away from that point. Such a point would, however, change the shape of the entire plant to something non-spherical. I don't have the math to visualize this properly at the moment. These would immediately kill all of the planet if large enough. If the material in the chasm disappears, atmosphere will fill it suffocating us. If the matter is moved, that matter has to go somewhere. [Answer] There's a lot of good science explanations already regarding what is or is not possible and to what extent. However, as stated in the original question: > > There is abundance of magic in this world... > > > In general, if it can be explained with science, it isn't magic (even if it appears to be magic to those who don't fully understand it). Magic really only includes those things that defy scientific explanations and/or disobey the laws of science. (Otherwise, it would just be science.) Therefore, it is worth asking what (if any) are the limits of magic in your world? Is it only capable of simple effects and parlor tricks? Can it ease manual labors (much like science can)? Can it influence things on a larger scale? Can it reshape worlds (like creating this chasm)? And so on. If magic is capable of producing the effect desired, then no scientific explanation is needed. However, understanding the science that the magic is defying allows you to make clear just how magical and/or powerful the effect is. If magic is responsible, then other questions arise, such as what caused the magic to happen? Was it a living being of some kind? Was it the result of "magical natural" causes (as opposed to "scientific natural" causes, usually just called "natural" causes in worlds without magic)? Was it deliberate, accidental, the "natural" result of other events, or something else? Over time, will the magic that caused it weaken/disappear, grow stronger, or stay the same? Was it a one-time occurrence or could/will it happen again? And so on. There doesn't even need to be a rational explanation if no one knows the answers to these kinds of questions. "It's magic." or "No one knows why/how." may seem like hand waving, but that's exactly what magic is. Most people in a world with abundant magic would likely accept explanations along those lines (though not necessarily in those exact words). However, many might have adverse reactions (e.g., fear, superstition, etc.) to large-scale, unexplained phenomenon. Others would likely prey on such reactions in a bid for dominance/power (by trying to blame certain individuals or groups for it, etc.). Still others might want to learn how to replicate it (as a weapon, for example) or prevent it from happening again. ]
[Question] [ Suppose there is a rogue planet. I was imaging what could be its energy source for life, and I remembered that photos of the center of a Galaxy look very bright. So my question is, can a galactic center be the sun of a rogue planet? [Answer] # Probably Not As far as we can tell, the center of each galaxy contains one, or sometimes more, [supermassive black hole](https://en.wikipedia.org/wiki/Supermassive_black_hole) hundreds of thousands to billions of times more massive than our Sun. I'll use our own, [Sagittarius A\](https://en.wikipedia.org/wiki/Sagittarius_A), for the rest of this answer. It has a mass of roughly 4 million Suns packed into a space roughly the size of the orbit of Mercury. While the planet could orbit the supermassive black hole, plenty of stars do, it's not a pleasant place for life. It would have an enormous [accretion disk](https://en.wikipedia.org/wiki/Accretion_disk) of material spiraling into the black hole, compressing, and radiating massive amounts of energy. It's this accretion disk which glows and could provide the energy necessary to sustain life on a rogue planet. Since the amount of energy radiating from the accretion disk will change as more or less material swirls around, it's unlikely the habitable zone around the disk, if one even exists, would remain stable. In addition, your rogue planet would have to deal with powerful and unstable magnetic fields, X-Ray bursts, and [jets of material](https://en.wikipedia.org/wiki/Astrophysical_jet). For example, in 2015 [a massive X-Ray flare was detected from Sagittarius A\](https://www.nasa.gov/press/2015/january/nasa-s-chandra-detects-record-breaking-outburst-from-milky-way-s-black-hole), possibly from an asteroid falling into the black hole, or tangled magnetic field lines. [Answer] Interesting concept, but probably a bad idea. Even if the galactic core could be used as a power source, [it is thought that life as we know it could not evolve close to the center](https://en.wikipedia.org/wiki/Galactic_habitable_zone) due to the high concentration of high-mass stars that are found there. Dangerous cosmic objects like neutron stars, pulsars, and black holes roam wild near the center, and supernovas or gamma ray bursts would sterilize a planet every few million years, causing evolution to start over. Complex life would find it hard to evolve in such a hostile environment. [Answer] Signs point to no. As the answer to [this Physics Stack Exchange](https://physics.stackexchange.com/questions/25706/density-of-stars-near-the-center-of-the-milky-way) discussion mentions, even a hundred times higher stellar density of the night sky as expected closer to the galactic center would brighten up the sky less than the full moon. While 100 stars per cubic parsec, which seems to be the common estimate for the galactic core, is a lot (we're at less than one star per P3) it's still not very dense as I understand it. And as others have pointed out, you want to be a bit off from the supermassive black hole in the middle so at best you'd get a very exciting night sky during your eternal nights. [Answer] # It's unlikely ## Galaxy Photo Clarification You stated > > I remembered that photos of the center of a Galaxy look very bright > > > Many photos of extra-galactic galaxies use filters, false-coloring or are enhanced* to emphasize certain features of the galaxy or combat disruptive effects such as light pollution. Examples: [M42](http://www.samirkharusi.net/filters.html), [Crab Nebula](http://www.narrowbandimaging.com/color_polarization_imaging_page.htm), [Horsehead Nebula](https://i.stack.imgur.com/k2Jb4.jpg), and M31: Andromeda [[4](https://starizona.com/acb/ccd/software/soft_total_ngc253pp.aspx)] [[5](http://www.astronomersdoitinthedark.com/index.php?c=164&p=547)]. If you look at software used in [[5](http://www.astronomersdoitinthedark.com/index.php?c=164&p=547)] , you'll see that the astrophotographer used stacking, masking, and photoshop to develop the final photo from a set of 44-291 photos (44 + 86 +71 + 90). Nevertheless raw photos are [remarkable](https://www.reddit.com/r/spaceporn/comments/5a2nh0/almost_35_hours_of_andromeda_galaxy_with_my_nikon/). ## Sol & The Milky Way From Earth, if you travel far enough from light polluted regions, you can see the milky way galaxy center with the naked eye. ([Paranal Observatory](https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/ESO-VLT-Laser-phot-33a-07.jpg/1200px-ESO-VLT-Laser-phot-33a-07.jpg)) ([wallpaper](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/ESO_-_The_Milky_Way_panorama_%28by%29.jpg/825px-ESO_-_The_Milky_Way_panorama_%28by%29.jpg)) ([space.com gallery](https://www.space.com/14249-milkyway-galaxy-photos.html)). Sol is 27,000 LY from the galactic center in the Orion–Cygnus Arm. The bulgy core of the Milky Way extends to about 10,000 LY and the 1 parsec galactic center contains 10 million stars. That being said, while it is relatively dim compared to nearby light sources with an [absolute visual magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude) of −20.9\* it is still a very bright object. By comparison the Sun has an absolute magnitude of +4.83 which is 20 billion times dimmer. Note: Absolute magnitude is defined as the apparent magnitude of the object at 10 parsecs. ## We Need To Go Deeper Morty! We've established that the Milky Way Galaxy is MUCH brighter than the Sun in terms of its absolute magnitude. It then follows that there must be some distance at which the Milky Way looks as bright as the sun (apparent magnitude). We're interested in whether there's a distance ($d$) at which the apparent magnitude is equivalent to the apparent magnitude of The Sun from Earth. This is a fairly simple calculation given the conversion formula between absolute magnitude ($M$) and apparent magnitude ($m$): $$M = m - 5 (log\_{10} d + 1 )$$ $$m = M + 5 (log\_{10} d + 1 )$$ Calculating the apparent magnitude of The Sun from earth using $M=+4.83$ and $d = 1/206265$ (1 AU in Parsecs) returns us an apparent magnitude of -26.74. Restructure the formula in terms of the distance (in parsecs): $$d = 10^{\frac{m-M}{5}+1}$$ Then plug and chug with $M = -20.9$ and $m = -26.74$ to get 0.67 parsecs (2.2 LY). \\This suggests that at 2 lightyears the rogue planet will see the milky way as brightly as we can see the Sun on Earth; however, it ignores a key premise: The absolute magnitude of a galaxy is calculated differently compared to stars since galaxies are larger than 10 par secs.\\ > > A galaxy's magnitude is defined by measuring all the light radiated over the entire object, treating that integrated brightness as the brightness of a single point-like or star-like source, and computing the magnitude of that point-like source as it would appear if observed at the standard 10 parsecs distance. > [source](https://en.wikipedia.org/wiki/Absolute_magnitude#Stars_and_galaxies_.28M.29) > > > Therefore, this may not be very reliable for the Milky Way. That being said, it is worthwhile to note that within 1 parsec of the galactic center there are 10 million stars, and that this region would be very bright since it does sit within the galactic core. My Conclusion: it can go either way. (I'll confer with an astrophysics buddy of mine for clarification and update this answer.) But we're not done. We've only considered the Milky Way Galaxy. What of the brightest objects in the universe? ## Quasars Quasars, or quasi-stellar objects, are active galactic nuclei of obscenely high luminosity. The brightest Quasar, [3C 273](https://en.wikipedia.org/wiki/3C_273) has an apparent visual magnitude of +12.9 and an absolute magnitude of −26.7 making it 4 trillion times more bright than the sun. Using the same calculation above, we find that it'll have the same brightness as the sun at 9.8 parsecs or 32 LY. The same arguments as before applies, but less strictly so. Side note: if a civilization were to develop on a rogue planet orbiting a quasar, they'd see some fantastic jets. I'd also expect them to use the jets as a time-keeping mechanism (much as we can use the moon to keep time in Lunar Calendars). ## Other Considerations Since your planet is rogue, you'll need to consider the following as well: 1. Electromagnetic Protection from solar wind. (Magnetosphere) 2. Goldilocks Zone (The planet needs to be warm and pressurized enough to sustain liquid water.) 3. Heating: Earth's surface heat is maintained primarily through solar radiation; but, 0.03% of the energy budget is originates from the radioactive decay of uranium-238 (238U), uranium-235 (235U), thorium-232 (232Th), and potassium-40 (40K). ([source](https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget)). In contrast, this radiogenic heating is what's responsible for our geologic activity from the soft-iron dynamo outer core that drives our geomagnetic shield to plate tectonics. [Answer] From a visual standpoint, there is a possibility of the accretion disk of the supermassive black hole at the centre of the galaxy releasing enough radiation to make a rogue planet orbiting sufficiently far enough away be lit up like the Sun. [![enter image description here](https://i.stack.imgur.com/UI0yo.jpg)](https://i.stack.imgur.com/UI0yo.jpg) The accretion disk as portrayed in the movie "Interstellar" Of course, as many other answers point out, visible light isn't the only sort of radiation you will be getting, and it seems very likely that visible radiation is not going to be more than a small percentage of the energy output of the accretion disk. I'm not able to find a good estimate as to how much energy is coming off the disk as light, but consider if we can see the supermassive black hole at the centre of the Milky way in frequencies from radio to x-ray from 30,000 light years away, then the radiation environment is probably sufficient to fry a planet orbiting a black hole, and possibly boil it away as it's orbit takes it closer to the centre. The ever helpful Atomic Rockets "[Boom Table](http://www.projectrho.com/public_html/rocket/usefultables.php)" tells us that it would take: 3.2 × 10^26J 77 Pt Energy required blow off Terra's atmosphere into space 6.6 × 10^26J 158 Pt Energy required to heat all the oceans of Terra to boiling 4.5 × 10^27J 1 Et Energy required to vaporize all the oceans of Terra into the atmosphere 7.0 × 10^27J 2 Et Energy required to vaporize all the oceans of Terra and dehydrate the crust 1.0 × 10^29J 24 Et Energy required blow off Terra's oceans into space 1.5 × 10^30J 359 Et Energy required blow off Terra's crust into space 2.9 × 10^31J 7 Zt Energy required to blow up Terra (reduce to gravel orbiting the sun) 5.9 × 10^31J 14 Zt Energy required to blow up Terra (reduce to gravel flying out of former orbit) So making some assumptions about the energy output of the central black hole gives you an idea of how far away the planet could be before the energetic output of the accretion disk destroys the planet, which in turn would tell you how many light years away it would have to be to be in the "safe" zone. This calculation does not take into account things like the presence of other stars caught in the orbit of the black hole, or take into account if the black hole is currently "active" (i.e. irregularly consuming larger amounts of gas, planets or stars), or if you have entered in a "[starburst](https://infogalactic.com/info/Starburst_region)" phase (the radiative pressure of the black hole's accretion disk has triggered a massive burst of star formation in the gas clouds that have been drawn into close proximity (several light years) of the black hole. [Answer] There are also dwarf galaxies out there, like [this one](https://en.wikipedia.org/wiki/Ursa_Minor_Dwarf). They don't seem to have a black hole in the middle, which makes an inhabitable planet in that region more likely. It is [theorized](https://en.wikipedia.org/wiki/Dwarf_spheroidal_galaxy#Evidence_of_Dark_Matter_in_dSph_Galaxies) that such galaxies may be formed around an agglomeration of dark matter instead of a supermassive black hole present in regular galaxies like Milky Way. However, unless you're willing to imagine an unknown way in which energy required to support life could be extracted from dark matter directly, your best bet is to have a regular star in the middle of a dwarf galaxy with your rogue planet orbiting it. [Answer] There is a brilliant video called "Civilizations at the End of Time: Black Hole Farming" by Isaac Arthur: <https://www.youtube.com/watch?v=Qam5BkXIEhQ> It describes civilizations that could live off of energy of a supermassive black hole, but definitely not in a sense you would expect. Worth checking out. Potentially, a sufficiently advanced civilization could also live on a planet orbiting black hole in old enough galaxy (where most of the orbits stabilized and material does not fall uncontrollably into a BH). By throwing material into accretion disk at constant rate it is probably possible to sustain consistent habitable zone. Although I don't really see the point in it for a society this advanced, they can just use artificial fusion instead. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/41817/edit). Closed 7 years ago. [Improve this question](/posts/41817/edit) The actual question is concrete and comes at the end, but first, I will explain the premise in detail. This fictional world is the same as our Earth. It has the same history. The same conditions. Suddenly, though, everyone can know what everyone else are thinking. Everyone in this world can then access other people's memories, thoughts, plans, ideas, beliefs, etc. This is not a technology, it's more like a telepathic power that everyone has and cannot lose. This new ability is at least as easy to use for everyone as using the five senses is in our world. Anyone can suddenly do it. You don't really need to know much about anyone in order to look into their mind. For example, you can sit in a hotel room, and think "Who painted this wall?" and immediately access that person's mind in a nearly unlimited fashion. Or you can ask "Who is looking into my mind right now?" or "Who is climbing Mount Everest right now?", and get access to their minds, too. It's almost like a perfect, intelligent search engine. There are almost no limits to this. There are, however, some limitations: * In the case of the painter, if the painter is dead or doesn't remember painting that room, you'll be unable to find an answer to your question. Unless someone else currently alive knows who painted the room (in which case you can still not access the memories of the dead painter himself.) So, you can only get information that currently living people still remember. * The main limitation is your own mind. There is way too much data to process, so you have to select what to focus on. It's a little bit like the public parts of the Internet. You have access to everything, but a single person couldn't possibly process it all. So you have to choose what you prefer to focus on. Even though you can sense the thoughts, etc, you don't feel that they are your own. You observe them with a distinct impression of them coming from outside of yourself. People with more empathy may feel more compassion or connection with what they sense, but in a similar sense that they would feel empathy if they observed a person going through something in the real world, through the senses. The degree of empathy depends on the individual, but it may be enhanced by the greatly improved ability to understand others. Except for the (massive) implications of this ability, it's the same Earth, and the same humans. # Question: What are the most radical things that will unfold after this ability is suddenly given to humanity? [Related question.](https://worldbuilding.stackexchange.com/questions/41816/world-where-everyone-can-know-what-everyone-is-thinking-what-changes) [Answer] 1: Lots of suicides almost immediately when people figure out the implications. Anyone who ever did anything that they're exceptionally terrified of others finding out about etc. 2: Lots of lynchings. In the UK mobs will be charging through the streets setting pedophiles and potential pedophiles on fire. 3: Even more lynchings. There is no longer such a thing as a closeted gay person. Anywhere. Including in every theocracy that punishes homosexuality with death. There is nowhere you can hide from someone searching for you, if they want to know where you're hiding they know. The streets run red with blood as any outed minorities are dragged from their beds by baying mobs. 4: Even more slaughter. Trans people are hunted in Russia, atheists are torn limb from limb for apostasy along the Pakistan border. Resistance fighters are dragged through the streets in oppressive dictatorships. In the brave new world it's utterly unsafe to believe forbidden things, even if they're only in your mind and you never utter a word. Nobody is safe, nobody can hide, guilt is certain, "justice" can be swift and brutal. [Answer] Way more criminals are immediately discovered than the authorities can deal with. A lot of bad people find out information that they can use to evil ends (either before getting caught, or to avoid getting caught). Cheating partners are exposed. Stock prices for a numerous companies (including some massive ones) crash. A lot of friendships are broken. Virtually every game that isn't based mostly on either physical skill or random luck becomes unplayable. Essentially, massive, immediate changes, almost none of which are good. [Answer] # A hive mind If everyone knows everything, we essentially only have 1 mind. We are one creature, where every limb can "act" autonomously, but everything it thinks/knows/wants is shared. We'd like a nest of bees, a giant octopus, an ant colony. [Answer] > > all humans suddenly get this ability > > > Unless this ability was coupled with an automatic "fail-safe" of some kind, everyone would go insane just as suddenly. Each person would look around, see everyone in sight writhing on the ground and wonder "What the heck is going on with everybody?" inviting 8 billion equally-bewildered minds to pour into their own - and promptly join the rest of the people writhing on the ground. Even if this ability built up gradually, everyone with an undisciplined mind (which would basically be everyone, myself included) would succumb to madness due to stray thoughts like "I wonder what people think of the new Star Wars movie" crushing them under an avalanche of information. --- (Edit, In response to the OP's clarification of the limits imposed on the otherwise unlimited) It still assumes too much auto-magical discipline and leaves too many premise-questions unanswered. What if "Who painted this wall?" involved 4 people? Would you access all four at once? What if the painter doesn't speak your native language? And what if the painter happened to be looking into your mind? Would it be a John Malkovich moment or some kind of infinite thought loop? ("Ick!" in either case) No matter how you shore up the built-in protections, you'd still have world-wide paralysis with everyone living in someone else's head for an indeterminate length of time. Put yourself in the situation described and ask how many people you'd check out. I'll bet it's a longer list than you think. If you doubt this, think "super models" (you, dear reader, pick the gender) and go from there. It's doubtful that society anywhere would be able to cope with this before enough of our fragile nuclear technology (reactors, not warheads) went off like popcorn and in time enveloped the world in a radioactive blight. A slightly more plausible scenario - one that doesn't inexorably lead to the end of the species due to neglect of technology - would be to have this ability "bestowed" on humanity earlier in its history; a time when nations were more autonomous, economies were less interconnected and world-ending technologies didn't exist. Even with that, humanity would take decades and multiple generations to adapt - and it would be very very messy. [Answer] # Social issues...? What about political issues? The societal issues would be nothing compared to the potential world-shaping consequences. Sure, bank accounts would be stolen, people would go crazy, blah blah blah, but what about the people with REAL power? The people in charge of well trained militaries, terrifying weapons, and powerful technology... these are the people who now have the world in their hands. Before the event, uncertainty and "diplomacy" prevents these people from acting rashly and just attacking anyone they please. Now that there are no secrets, what happens? World powers would know all of each other's motives and secrets, and the secrets of all their enemies. The outcome of this could vary from total anarchy to the formation of a super government all based on timing and whether or not the right people ask the right questions. Do allies stay allies? Do new alliances form, or does everyone split apart? Does everything turn into a mess because nobody wants to listen to anyone anymore? Small seed events could thrust us down widely different paths. For instance, the United States could have their systems taken down by any number of people with the ability to do so now that secret systems are no longer secret. Sure, you can't just ask "what's the weak-point" and expect someone to know it, but given the amount of people who would like to hack into government systems, it's likely that SOMEONE would succeed. If our core systems are taken down at a critical time, we could be open for surprise attacks. You may say that surprise attacks wouldn't work, but knowing an attack is coming doesn't necessarily make you prepared for it, nor does it make your reflexes or tactical logic any better. Really, anything is possible. World powers get nuked by `<insert enemy here>`? Sure, if someone with the ability to do so acts rashly with their new powers. World powers retaliate with further nukes? Sure, if they're not a total mess or (again) the group of people with the ability to do so acts rashly. No nukes are launched and instead we're locked in a furious diplomacy stalemate? Sure, if people are overwhelmed with the influx of information and secrets. Small states all warring with each other? Sure; it's a micro version of world powers fighting with each other. It all comes down to what secrets are exposed and how the current governments react to such secrets, and how good they are at handling this information. Oh, and social meltdown, but that's kind of irrelevant in the face of big bad enemies with lots of scary weapons. ## My opinion I think that various governments would be OVERWHELMED with the completely unmanageable amount of problems they're now facing. Not only do they have to deal with the breakdown of society, all their own secrets getting loose, and all these new enemy secrets being discovered which warrant immediate action, they ALSO have to deal with single-minded enemies who are now more inclined to attack. Governments are in a panic with various members of staff all stressing over the constant revelations of new information (both that they discover themselves and what is brought up by others), and they stop functioning properly. The first attacks made by enemies (doesn't matter who attacks whom) would put societal problems into perspective, and any working governments would become focused on external problems rather than trying to focus on all of them. Without regard for consequences (and because everyone is entirely over-stressed and jumps at the opportunity to focus and unite), governments of the world counter attack any potential enemies, and bolstered by their success, proceed to systematically wipe out all enemies of the nation. Various terrorist organizations are simply eradicated and any further resistance is met with retaliation. It doesn't matter that enemies know you're coming; if you're more powerful, you'll still win. Various nations are turned into military states to quell the massive social uprisings due to all the attacks, but are unsuccessful in maintaining it. All governments eventually break down, but we don't get thrust into thermo-nuclear war because systems aren't functioning anymore. It's a typical anarchy scenario, but the aftermath's regrouping efforts would build an entirely different society. There's less emphasis on leadership and action and more emphasis on understanding. New societies are no longer formed around secrecy and greed. Property, wealth, none of that matters anymore, because you can't keep it to yourself properly. Those who are incapable of understanding become the minority; since they don't ask the right questions or don't listen to the answers, they can't survive with all these people who DO understand each other. These new societies are completely unrecognizable and live in relative peace, since misunderstandings are basically nonexistent. We become far more homogeneous in our thought processes and technology advances at a considerable rate due to the propagation of ideas. [Answer] If society manages to last more than a few weeks then I imagine we will develop knowledge hiding strategies. If anyone can read my mind then I am going to make an effort to not know some important information. For example, I can mind read anyone's usernames and passwords to websites, including online banking. To counter this we would probably move to fingerprint based access or multi factor authentication. [Answer] ## I wonder what Bills Gates' bank details are? Total complete and utter chaos, followed by a lot of divorce. Eventually a much more civilised and balanced culture should rise, without any hangups about sex. Someone will put a lot of effort into creating a drug that blocks the effect. Everyone will know what you did last summer. [Answer] Divisiveness and hate ends. People see another person's entire thought process before disagreeing or marginalizing them. We realize that most people who we disagree with aren't unreasonable. And the true sociopaths become much easier to avoid. [Answer] In addition to Bez and Murphy's answers, the key cultural change that occurs to me is that stability will rapidly settle in on a macro level: * planning battles, coups, takeovers etc. Will not be possible clandestinely * assassinations will also not work * individuals will have advance notice of these sorts of things, so the only way a war can be successful is to use attacks that planning cannot be the key factor for. Examples: * An attacker decides on a frontal assault - so the defence builds fences - so the attacker has scaling gear - so the defence has riflemen targeting those coming over the wall - but the attacker knows where they are and lobs mortars - but this means the defence will have deliberately moved in time...etc * 3 candidates are in the running for a political position, and everything about them is known, so those with skeletons in the closet no longer have a closet. All the history and aims of each candidate will be clear, so no canvassing or political roadshows required. The best candidate for the population should win every time. So dramatic upsets based on war are unlikely, immediate changes to political parties and organisations to remove those with criminal or immoral pasts and aims will happen, and the end goal will be cultural stability. (Possible exception, and useful story concept - individuals with brain damage or mental impairment that either blocks this 'telepathy' or removes their ability to think logically may be able to work outside these constraints and cause unanticipated damage or trouble.) --- On an individual level, creativity may be enhanced - inventors who have a new theory or idea may be able to tap into all those who have associated concepts, so technology development may rapidly accelerate. Creativity, however, may be impacted - the attraction of stories and films may go if every possible audience member already knows the entire story... [Answer] In the immediate term, as others have said, murders, suicides, assaults, and social chaos. In the intermediate term -- a year or more out -- we would develop a social convention/law of not reading others' minds without permission. Certain authorities would be exempt from this under certain circumstances (like obtaining a warrant). People who read others' minds without permission would probably be severely punished. How would the authorities know whether you did this? Simple -- they'd read your mind. Maybe once a year, everyone is asked whether they committed this crime, and punished accordingly. [Answer] We become depressed as we realize socialisation becomes utterly meaningless if any behaviour masking your thoughs is futile. We isolate ourselves as being social is worthless if everyone already can judge you no matter how you adjust your behaviour. In the end we even stop caring if we live or die. Without hope of freedom there is nothing worth to work for in any world. Perfect recipe for creating depressed alcoholics who give up on life - en masse. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/38265/edit). Closed 7 years ago. The community reviewed whether to reopen this question 5 months ago and left it closed: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/38265/edit) I had so much fun reading [How will our world change if all men suddenly die?](https://worldbuilding.stackexchange.com/questions/38103/how-will-our-world-change-if-all-men-suddenly-die) that I decided to register here. It also made me wonder about the opposite case: In a world... with today's technology and level of development there is a Mad Scientist. A man, to be exact. One day he concludes that women are responsible for all evil in the world and starts to bioengineer a virus. Super advanced virus, because he's a genius. A virus to solve all the world's problems - in his wicked understanding. He succeeds and the virus starts spreading, very stealthy, via air and water and all the other possible methods of infection. Soon after the entire earth population is infected. And then, in one day, the virus activates and all female humans die, almost instantly. Basically, only men are left on earth, forever. It is well established that men would have a problem living for very long since they can't give birth, but would they be able to develop a way to actually make babies without women? [This is already kind-of happening](http://clippings.ilri.org/2010/12/15/now-men-can-make-babies-without-women/), although women still have to take part. How will the world change? Will the civilization survive? What are the consequences? (Answers giving the differences between this and the opposite case are more than welcome!) [Answer] OK I will go on with a timeline scenario again (as in the previous question) and do my best to be as good hater-magnet as I did on the previous question. 15 seconds after the death of all women: A lot of vehicles crash all over the world, although the count would not be as much as it would have been if all men had died. Considering that there are disproportionately more men drivers than women drivers. However freaked out men (seeing their friend/lover/wife/daughter dying within a moment on the front seat) will still get many millions of fatal accidents all over the world. This would result in major havoc, confusion and frenzy all over the world. 1 minute after the incident: There would be major uproar all over the world. Hospitals (specially maternity homes) would be particularly hard-hit. Communication channels (phone lines) would be overloaded with men all over the world calling home to ensure everything is safe and fine. 10 minutes after the incident: Considering that a lot of roads would be blocked (due to jammed vehicles and crashed cars) and the overall confusion and frenzy, some not-so-nice men would try to take advantage of the situation. There would be a wave of rioting, looting and plundering all over the world. 15 minutes after the incident: There would be a possible outage of communication channels based on government orders. Many governments all over the world might order a complete shutdown of internet and phone lines (both landlines and mobiles) in order to not let the other countries learn what has transpired to them. This would be specially expected of countries such as India, Israel, North Korea, Iran, Saudi Arabia, China, Russia, USA, UK, Egypt, Syria and Pakistan. The reason would be that if this catastrophe is limited to their country (as the governments may think), it might provide their adversary nations a best opportunity to storm their borders at this time of extreme weakness. If it happens (very likely), it would send the world in a communication blackout, increasing the confusion and violence. 30 minutes later: Most countries around the world with a strong military would be put on curfew in order to contain the rioting and violence. Secure lines between national heads and secret service agencies would have confirmed by now that the catastrophe is global. This would actually relieve most of government leaders around the world, with the thought that they wouldn't be raided by their rival nations in this time. Many might actually plan raiding their adversaries. Such incidents, if not involving nuclear powers, would be very gory, but wouldn't have much impact on the global scenario. 1 hour later: Communication channels would be opened gradually, with restrictions. International relief operations would commence. Relief referring to cleaning the dead bodies off roads and houses. The poor dead women would be piled up outside the cities and rural settlements and an urgent meeting of the world's smartest minds (not the government heads, but the scientists and think tanks) would commence about the disposal of these corpses. I cannot posit if the meeting would be over dedicated internet/phone lines or in person. 1 day later: There would still be a lot of rioting and plundering going on around the globe, despite the strict curfews in place. Relief workers (collecting corpses and transporting them outside the cities) would be operating under the security of armed forces. By evening, most government around the world would order to either: * burn all the corpses in high temperature fires in closed facilities and then bury all the remnant material. This would probably be the line of action of western countries, India, China and (possibly) several African countries. * bury all the corpses in huge, deep (more than 20 feet deep, for hygienic reasons) communal graves outside the cities. This would probably the course of action of most Muslim countries, Japan and most Christian countries of Africa along with (possibly) Israel. * dump all corpses in the sea. This would be a city-wide policy of several coastline cities such as New York, Shanghai, Karachi, Mumbai along with many others. 2 days later: Relief operation would be initiated for taking all those jammed and crashed cars off the roads. Also, in several countries of the world, military would be authorized to shoot insurgents on sight. 1 week later: The first wave of depression would surge globally with millions of suicides all over the world. Although order would have been restored in most parts of the world, many would still be burning in flames of anarchy and violence. 1 month later: All countries of the world unite to wipe out any and all anarchy. Scientific meetings are organized all over the world in efforts to find the cause of this mass extinction and to find ways to save the human race. (And no, [the link](http://clippings.ilri.org/2010/12/15/now-men-can-make-babies-without-women/) posted by OP still states that women would be required for carrying the fetus. The process only eliminates the need of an ovum for making a baby). 6 months later: Suicide rates continue to surge. Although the standard of life apparently rises for most 3rd and 2nd world countries (irony. with all women gone, half of the resources in developed world are now shipped to developing and 3rd world countries), the horrible consequences of not having any women left in the world would continue to frustrate leaders, scientific personnel and common man alike. 1 year later: Suicide rates return to pre-catastrophic times. Order is maintained all over the world. All countries are cooperating vigorously in search of a way to save the human race, with no progress made whatsoever. Food would be in excess and everything would be very cheap ... but with the consequence of living a pointless, frustrated life. 10 years later: Cities and towns start merging with waves of mass migrations as there just aren't enough people to keep cities alive and active. People from towns and villages would move to cities as men die each year, leaving little population pockets here and there. These population pockets would continue to merge in places where mega cities once used to stand. 20 years later: After cities and towns, now whole nations and countries start merging. This would specially be a necessity in the western world where the population density is very low. All efforts of the world are now focussed at finding a means to repopulate the world. 40 years later: All the human population of the world exists as one country consisting of disgruntled old and middle-aged men. ... And so the things would be, until the population continues to plummet. The last shreds of human population being wiped out with a sorrowful ceremony of ritual suicide ... [Answer] It will be the end of humanity. All porn sites will be raised to religious status. It will be paramount that they are preserved forever! Goats and sheep will have a raised value in society. Some few scientists will be working overtime to find a way to reproduce humans, possibly by using cows or some other domesticated uterus as a home for human fetuses. Lots of violence, especially in areas without internet to supply porn. The term Mother-F\\\\\* will become a term of respect... [Answer] # Healthcare falls to pieces. While males make up the majority of professionals in medicine, women make up the vast majority of nursing and healthcare. Nursing is not about changing bedpans and making beds. Nursing is about making sure that you actually get well again after you have seen the doc. Nursing is an academic profession, with extensive science and research backing it up. Think of it like a (association) football team: the doc is the goalie, the nursing / orderly staff is the rest of the team. Take away the goalie and your team loses a key player, true... but lose the team and your goalie is truly screwed. Another analogy would be architect vs builders. Sure, the architect may propose a fancy solution to a need... but it is the builders that make sure it gets put in place and does not fall apart. The builders are the ones with their feet on the ground and the experience of making sure that buildings are not just looking nice on a blueprint but that they also do not leak through the roof, electrocute tenants when they get into the shower, or have doors that lead outdoors to a 10 story plunge to the ground. And you would be surprised how often this is the real case when it comes to hospitals, where nurses catch the blunders of doctors. With 3.5 billion corpses littering the world it will not be long until plagues of all sorts are rampant... and then the world ends... not with a bang, but with the most epic man-flu you ever saw. [Answer] First of all, if all women die; the birth rate would go down to 0. Obviously, because there are no babies to be born without women. Furthermore, the old men left in the world would die and then more and more people die as people start to grow old until, finally, the human race goes extinct because there are no babies to fill in the places of the old people who are dying. [Answer] The same mad scientist would be ordered to create an alternative means of human reproduction. Shortly after a new generation of women will be created to replace what has been lost. [Answer] A few things come to mind. * More pizza. * More beer. * More football, basketball and baseball. More box fights. * More parties. * Fight clubs become common past time occupations. * More flexible and lenient work hour regulations due to the items above, and because after a few years no school hours dictate early mornings any more. * More swear words. * More accidents with children for a few years, but almost all minor. * After a few years it will be possible to have pregnant men, animals carrying human fetuses, or artificial wombs. Mankind will not die out. * After a 2000 year hiatus, male homosexuality becomes common again. * The above notwithstanding, a virtual reality/movie porn business becomes a major economical power house, driving VR technological development. The telecommunications industry will have a mandate to serve every household, however remote, with broadband internet access, for, well, educational purposes. * If between Jan. 20, 2017 and some time 2025: The deceased president is succeeded by the not-quite-yet deceased vice president. * The table cloth industry collapses. * The above is part of a transformation of houses to man-caves in which provisions for recreational sports (including chess, poker!), smoking, drinking and drugs in general become the center pieces of the homes. ]
[Question] [ Around 1100 years in the past, a great empire spanned most of the known human world. At its center was a great city of learning and discovery, where humans first developed methods to channel omnipresent magical energy directly into their wondrous inventions, setting civilization on the cusp of an era of magitek - technology that was based upon and powered by magic, yet able to be used even by a layman via simply touching a rune or speaking a verbal command. However, a massive, deadly accident left this city largely destroyed, as well as sealed away beneath a conventionally impenetrable barrier. The loss of technology and magical power accelerated the fall of the empire into civil war, ending in a 300-year dark age for most of humanity. Despite this, magic remained present in human society, and the profession of sorceror remained highly prestigious. Humanity in the current day has also already experienced a more conventional industrial revolution and technologies such as the combustion engine, electrical power or flight are widely available. My question is, why would the (deathly curious and willing to do a lot to make their lives easier) humans, splintered into many separate nations with no central oversight, never seriously foray into magitek again and just be content with developing conventional technology, despite having both folklore related to the heyday of the old empire as well as occasional turnups of actual magitek artifacts across the land? [Answer] Why wouldn't the descendants of the survivors delve into magitech? Because some of the underlying framework still exists. But why wouldn't that be a good thing? Why wouldn't it mean that the survivors' descendants have an even easier time in recreating the lost magitech? The answer to that is because of the nature of the accident. The accident didn't just destroy the civilization that used the magitech, it poisoned the underlying magitech framework. As a result of the accident, any magitech has become deadly or harmful. That's part of what destroyed the civilization, and it's what is preventing a magitech revival. Quite simply, magitech isn't that hard to replicate. You perform the enchantments, and it just works. However, because the web of magic that underpinned the tangible interfaces has been damaged/poisoned/corrupted, tapping into the magitech web is a recipe for disaster, not power. Anyone who creates or uses a piece of magitech is doomed to a horrible fate... death, or worse... The problem with duplicating magitech is now not just the problem of recreating the tangible interfaces, but recreating the entire underlying web of enchantments without using any of the same approaches. Do almost anything the same way as the creators of the magitech did, and your new approach also gets poisoned. So, in effect, to safely recreate magitech, you'd have to not only completely reinvent it, but you'd have to do so without using any significantly similar process. No doubt the original magitech was made the way it was in order to be simple and cheap... so any new approach that won't be poisoned by the old just won't be as easy or cheap. Think of it using this analogy: Imagine that every scrap of copper in our technology has somehow become - or creates - a horrible, insidious contact toxin. How would you recreate modern electronics without using copper? It's not that the knowledge has been lost, the problem is that it still works, and is still useable, it's just that if you use it, you're poisoning yourself. The problem then becomes how to replace copper entirely. [Answer] The methods to make magitek are not obvious at all. [![hagia sofia](https://i.stack.imgur.com/PLE4K.jpg)](https://i.stack.imgur.com/PLE4K.jpg) [source](https://www.independent.co.uk/news/science/archaeology/hagia-sophia-roman-constantinople-istanbul-archaeology-b1782059.html) Technological methods get lost. An analogy is ancient architecture. Medieval persons 1000 years later could bake a brick, and stack them up. But medieval architects could not build a hanging dome like the Hagia Sophia even though they could visit and stare at it and wonder. It is not obvious how such a thing could be done. So too your ancients. They accumulated some serious bodies of knowledge in the creation of magitek. These were not codified and written down but passed along as a trade - understood recipes to make and do things. These recipes were leveraged by the administrative and organizational might of the ancients just as a piece of technology we hold in our hand today owes its existence to a multitude of mines, factories and supply lines. Your people cannot replicate magitek because they have lost more than just the recipe of how to put the thing together. [Answer] # The disaster left a lot of demon code. While the full details may be lost, one thing that is known is that a lot of magitek was corrupted with viruses and corruptive spells on them. Anyone who builds magitek will find that unless they have as advanced as military grade firewalls that the ancients had that their magitek gets hacked by demon code if they go in the wrong places. While people have experimented with reviving magitek, it has been disastrous for most. [Answer] This city has library with one of a kind magic books and manuscripts gathered from all known world during centuries, and because of this: > > However, a massive, deadly accident left this city largely destroyed, as well as sealed away beneath a conventionally impenetrable barrier. > > > nobody can read this books one more time. There are some basic "Magic for Dummies" manuals spread around the world, and sorcerers has access for them, so magic is not lost. But manuals has basic knowledge only, and even if somebody gathers all magicians and require them to research and improve magic, it will took much more than 300 years to return back to level old empire had. [Answer] Worldbuilding.SE is full of questions about how long it would take to recreate modern society if X gets teleported 1000s of years into the past (e.g. [How long would it take to create a Windows 1.0 capable machine from complete scratch?](https://worldbuilding.stackexchange.com/questions/54976/how-long-would-it-take-to-create-a-windows-1-0-capable-machine-from-complete-scr) , [If 120 experts in 12 different fields were sent back 10,000 years, could they recreate the 21st century in 100 years?](https://worldbuilding.stackexchange.com/questions/158429/if-120-experts-in-12-different-fields-were-sent-back-10-000-years-could-they-re) and [Speedrun to the moon in one lifetime?](https://worldbuilding.stackexchange.com/questions/186728/speedrun-to-the-moon-in-one-lifetime)). Inevitably the answer is: It takes an incredibly long time. So what if Magitek is just as complex in the same way, except it's all about fulfilling magical requirements. Let's say that simple Magitek has a similar complexity to a 1990s calculator. You need way to shape the housing, store energy, figure out how create very thin pieces of metal, where to get metal, how to refine metal, how to heat metal, how to create a display, etc. etc. etc. Put more simply: To build even a simple magitek device you first need to build the tools to craft the tools to build the machines that will build the machines that will get you your first magitek artifact. Creating magitek artifacts requires a global supply network (e.g. specialized types of mana from across the world that interact with each other in just the right way), it requires incredible specialization (the guy who spend his entire life studying and creating magitek machines that can weave incredibly fine magical 'cloths' that are the basis of making magitek interactive. Or what about the guy who specializes in creating chambers where you can safely 'superpower'/heat mana to the point where it changes it's type/shape/form/affinity/something else), etc. etc. The point is: Even if you a magitek artifact, it won't allow you to recreate it, because you don't have the prerequisites. Even if you had books describing every single step in the process it will take decades if not centuries to go through all the steps. It's like humans getting their hands on an alien artifact ( [What could prevent us from making alien technology if we had the schematics?](https://worldbuilding.stackexchange.com/questions/136971/what-could-prevent-us-from-making-alien-technology-if-we-had-the-schematics) ), but instead of missing future technologies and infrastructure, we just miss the infrastructure and specializations that were developed in the past. Now let's make one little deviation from non-magical technology: Imagine that all the steps on the way hold little to no value by themselves. The only reason the old empire pursued all the steps leading up to their magitech discoveries is because they valued magical knowledge for its own sake. They invested absurd amounts of money into magical universities. # So back to the main question: So what stopped all that from developing? Now that we have established that it takes a lot of people collaborating to get all this off the ground it means that just a couple of high profile failures can be incredibly demotivating. Maybe after the dark age there were one or two countries who were trying to recreate it, but all of them got invaded as they didn't have enough money left to protect themselves. Maybe after the dark age there was another country which tried to recreate magitech and destroyed their magical capital in a huge magical accident (ideally with some handwavium justifying why the same thing can't be weaponized). So everyone believes it's possible to build... but everybody always feels the time isn't right yet. [Answer] Curses A sorcerer driven insane by the disaster poured all his considerable skill and knowledge into cursing anyone who tries magiteck, and recruiting new followers for a secret order that keeps the curse going. They have splintered into cells to protect the activity and keep renewing the curses. Whoever tries it finds himself suffering disaster after disaster. [Answer] ## Permanent Enchantment is a lost art Thanks to scientific advancements, the sorcerers today are much more powerful than they were 1000 years ago, but somewhere along the way we forgot how to make enchantments permanent. So, while a spell can solve any immediate problem, it can't really be used to solve a continuous problem very well. For this we use technology. But the ancients could cast permanent enchantments on things and thus solve continuous problems without the use of technology. How they did this, we do not know, but we now call it magictech. We see similar things in our own real world history. For years, ancient technologies like Damascus steel and Roman Concrete baffled modern science. When we finally figured them out, it turned out the secret was in the impurities that these ancient civilizations did not remove from their works as opposed to something they intentionally put there. In Rome for example, they would mix their concrete with whatever water was most available (typically sea water) instead of fresh drinkable water like we normally do today. The salts became part of the concrete's structure and made it far more resistant to salt water corrosion. In India, there is a common impurity in iron ore that you don't find in other parts of the world that was responsible for forming the higher quality Damascus steel. [![enter image description here](https://i.stack.imgur.com/FKtyZ.png)](https://i.stack.imgur.com/FKtyZ.png) In ancient times, this made steel from India especially sought after, but during the industrial revolution, improved refining practices began removing this impurity from the ore making it fundamentally no different than any other iron ore. So when scholars began comparing modern steel with Damascus, they were shocked to learn how good this ancient steel was, and for decades, they were not able to figure out how they did it; so, for decades we called it a lost technology. These technologies were difficult for modern science to solve because we kept trying to figure out what they were adding to their materials when in fact, the secret lied in what they were failing to remove. So even when we studied their writings we could not figure out the secret, because even they did not know what made their materials better. Likewise, during your setting's dark age, sorcery could have continued to evolve. While it may have regressed in some areas, it would have also moved forward in others. So, imagine magic comes from some ethereal source that surrounds us. To case a spell, you must extract mana from the ether, and then manipulate it into its desired form. But the ether is not just a cloud of mana, it contains all sorts of energies, many of which are detrimental to casting; so, the first thing any sorcerer from the late dark ages onward does is isolates the mana from other ethereal energies allowing him to maximize the power and predictability of his spell. It is so ubiquitously done that it is the very first thing young mages are taught to do, but in the ancient times, people did not isolate mana very well to cast spells; so, one group of wizards found that when they cast spells on certain lay lines, that they could be used to make permanent enchantments. The reason these lay lines don't work for modern mages is because it does not occur to them to use the unpurified mana that exists there; thus, this ancient form of spell craft is lost to your modern civilization, and with it the kind of magic they need to make Magitech viable. [Answer] The massive deadly accident was caused by or produced some sort of magical rot or evil that continues to pervade all magic performed thereafter - spreads throughout magic like a virus. Every time that someone tries to experiment with magic, they encounter this and receive injuries or curses or something that is a result of the left-over blight. The sorcerers who continued to perform magic after the accident had the rare skill of being able to purify or control magic in spite of this, but over time this became a lost skill and as mundane technology advanced, the need for this ability became less and less, and so it was finally forgotten. [Answer] The rules keep changing. Imagine if, in our universe, the laws of physics kept changing. E=mc^2? Oh well today it's E=mc^3. Every physics formula is subject to change without warning. Basically everything might be fine tomorrow or maybe the universe will explode. Turns out, magic is like that. It's energy drawn from a neighboring universe but the "neighboring universe" can shift from one to another at any time without warning and the new one may have completely different rules. The original magitek society was built during a time of unusual stability -- the rules for magic may well have been unchanged for thousands or millions of years and they didn't even know it could change. Until it did. When the shift occurred, the magitek devices drawing power (and, perhaps, a relative handful of sorcerers who were actively using magic when the shift occurred) experienced major malfunctions. Magic may be in a state of constant flux at the moment. The rules could change daily. Sorcerers can still access the energy, probe it, and use it, perhaps not unlike tapping into a totally unknown power wire where you're not sure what the volts or amps are or if it's AC vs DC. First you find out, then you buffer some energy, then you use it. That's sorcerers. They have not figured out how to make Magitek items that robust. They need a steady, known supply. If magic settles down again, Magitek could take off again. And nothing stops you from making a device today, based on today's rules, but you don't know if it will work for an hour, a week or a month, and if it fails, you don't know how spectacular that failure will be (maybe you can invent a "magic circuit breaker" to avoid catastrophe but the constant shifting of rules still means your device stops working and has to be redesigned to fit the new rules, which, again, keep shifting). (To expand the electricity analogy, imagine trying to make a hair dryer that can work off of literally any power source. You can plug it into a USB port. Or a 120V US wall socket. Or a 240V wall socket. Or a wall socket in Japan. Or Germany. Or directly to the raw output of a nuclear power plant. It's probably possible but represents a big challenge and ultimately makes your hair dryer impractical -- you're spending more on the converters and buffers than on the device. This is what the people of this world face with magic. They can make the devices but since the properties of the power source keeps changing, the devices become something between impractical and dangerous. The sorcerers themselves might occasionally tap into the magic network and go "Woo! Wow. Okay. Not using magic today I guess. Check back later.") [Answer] If the accident you were talking about that triggered the dark age involved magitek, everyone would be wary of using such devices again. The threat of another disaster would keep people wary and distant. [Answer] A combination of extreme personal sacrifice, boobytraps and cynicism. You could state that building up magical "infrastructure" requires both trial and error, the willing surrender of one's life-force (it kills you) and after the accident, there are unknown magical instabilities which can be detonated when extending magical "infrastructure" which could completely destroy that set of magical "infrastructure" and force a nation to start from scratch again. In the prior era, an old sage may consider it an honor to give the last few years of his life to improve the lives of all humanity for all time. After the event where the magical "infrastructure" of countless generations of human sacrifices was not only lost but also almost destroyed humanity, the perceived risk to reward ratio of self sacrifice has gone from guaranteed saint to dubious self-execution. Back then you could kill yourself for the good of all, after the collapse and tainting of unknown swathes of magic, killing yourself could just destroy what few magical artifices your culture has retained - so better to just enjoy your own life then be remembered as a fool who damaged the nation through the hubris of trying to help. [Answer] They wouldn't. From time to time you hear about those, who pursuit the old ways of magitec. They die in smaller accidents or are denunciated by their neighbours. No one without direct benefit from magitec research would tolerate it in their direct vicinity, because it is so dangerous when it goes wrong, so private approaches to rediscover the old tech usually fail quickly. Of course the private pursuit of magitec is forbidden, a ruler can't allow it, sudden explosions and collapsing buildings can't be ignored. Pretty much every country has a program going on to rediscover the full potential of magitec, but due to its unstable nature sabotage to this projects is easy and no country wants to allow another one to rediscover too much of it, as it would be a too significant disturbance to the balance of power. If that still seems to little as reasons for why magitec did not return, you can make it very visible. It could take days to create a new magitec item and it could produce a huge column of light as a side- effect (or something similar visible). So although humans still pursue this path, it leads them nowhere as they fail on their own or are brought down by other humans. [Answer] The gods forbid it! Death to the sorcerers!!!! BURN THE WITCH!!!!!!! i.e. the usual stuff, ho-hum, nothing to see here, move along now, folks - just a servant of evil and his nag being roasted. Move along, folks - move along...if you know what's good for you... [Answer] [The ancients left warnings](https://en.wikipedia.org/wiki/Long-term_nuclear_waste_warning_messages) that persist to this day. [Answer] ## Every magitek item was a one time prototype While redeveloping technology at the end of the Dark Ages, they realized the old magitek stuff could not be repaired or modified, because the magic to repair or change things was unknown, the makers did not leave the information. Probably, it had never been there at all. Further development of a magitek device depended on its original maker, who envisioned it, then recreated it. Others could only imitate it. Each magitek device was a unique work of art. The maker wizards themselves had little understanding of the physics of their creations. When a wizard died, his nifty gadgets would die with him. Mankind resorted to technology-only solutions and math/method schooling instead of magic, to make sure things can be reproduced in an industrial way and modified to the needs of a new design. *you need prototyping and* reverse engineering** Despite magitek engineers being Alice in Wonderland in their own projects, they were very creative and produced things from scratch quickly, which is an activity that still exists, also in modern technology. It is the noble art of prototyping.. and even nowadays, often only the prototypers know how they achieved their results. But when engineers take over to create a product from the prototype, it can be reverse engineered to produce a proper design and building plan. Technology can be analyzed. With magic, that is not the case. Magic can only be applied, not understood. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/107341/edit). Closed 5 years ago. [Improve this question](/posts/107341/edit) I want to have a setting where South Africa instead of ending the [apartheid](https://worldbuilding.stackexchange.com/questions/78967/how-to-keep-apartheid-alive/78977#78977) peacefully it splits across the racial lines. Whites form a separate state in the Western Cape or any other province as long as it has an access to ports. And expel the rest from its part. The split could happen during the 80's or early 90's. What factors would make such move most plausible? Maybe pressure from the West of potential military action instead of boycott during the 80's where communism was still a threat. [![Province Map](https://i.stack.imgur.com/SnZ7g.jpg)](https://i.stack.imgur.com/SnZ7g.jpg) [Answer] Nothing would make it feasible. South Africa is like anywhere else, they need a cheap labour force. Dividing it along racial lines would collapse the economy and lead to war very quickly. Expelling the africans in such huge numbers into already belligerent neighbours would lead to war, starvation, and all the rest. The colour of his skin does not mean he will be welcome in another african country, plenty of genocides happen over there. I see it on the news, I cannot see the difference between 2 tribes, but they can and there is some horrendous stuff going on sometimes. [Answer] Congo crisis.<https://en.wikipedia.org/wiki/Congo_Crisis#Political_legacy> > > The chaotic violence of the crisis and the fate of the country's > whites, many of whom entered Northern and Southern Rhodesia as > refugees, contributed to the widespread belief among whites there that > black nationalist politicians were not ready to govern, and prompted > fears that immediate majority rule in Rhodesia might lead to a similar > situation. > > > This happened, and was already bloody and chaotic. In this timeline, it is worse. It is the divergence point. 1974: Massacre in Mozambique. <https://en.wikipedia.org/wiki/Carnation_Revolution> > > The Carnation Revolution (Portuguese: Revolução dos Cravos), also > referred to as the 25th of April (Portuguese: vinte e cinco de Abril), > was initially a military coup in Lisbon, Portugal, on 25 April 1974 > which overthrew the authoritarian regime of the Estado Novo.[1] The > revolution started as a military coup organized by the Armed Forces > Movement (Portuguese: Movimento das Forças Armadas, MFA) composed of > military officers who opposed the regime, but the movement was soon > coupled with an unanticipated and popular campaign of civil > resistance. This movement would lead to the fall of the Estado Novo > and the withdrawal of Portugal from its African colonies. The name > "Carnation Revolution" comes from the fact that almost no shots were > fired and that when the population took to the streets to celebrate > the end of the dictatorship and war in the colonies, carnations were > put into the muzzles of rifles and on the uniforms of the army men by > Celeste Caeiro. > > > In this alternate timeline, the Carnation Revolution is a bloody massacre. The Portuguese who did not escape into Rhodesia or South Africa are slaughtered in the streets. 1979. Rhodesia falls. The white government of Rhodesia falls in a similar manner. Having been forewarned by the fate of the Congolese a decade ago and then the Portuguese next door, many of the whites fled before and during the slaughter of white citizenry. 1980. Exodus. Reading the writing on the wall, white South Africans from the north of the country begin a southern movement down towards the Cape. Under pressure from the white refugee populations the South Africans begin moving black people out to make room, and also because of increasing fears of a black uprising. 1981. Uprising and chemical warfare. These actions serve to trigger the uprising. This is accompanied by a separate group of desperate black migrants moving South out of the chaos of the fallen states and opportunists seeking spoils from the destabilized northern part of South Africa. The more organized of these factions are opposed by a brutal military response by the retreating apartheid government, using [Project Coast](https://en.wikipedia.org/wiki/Project_Coast) - chemical weapons designed in anticipation of this circumstance are used against black revolutionaries and also black refugees and black South Africans. The horrors of these actions lead to the total ostracism of the Apartheid government, freezing of bank accounts, and a refusal by both Soviets and Western governments to give them aid. 1982: [Samson option](https://en.wikipedia.org/wiki/Samson_Option). In the last refuge of the Western Cape, the white government (as well as a massive white refugee population) threatens nuclear action against the encroaching groups of blacks. The Israelis give credence to this threat, having helped the South Africans design their bomb. International forces come at last, setting up a demilitarized zone walling off the white government from the rest of the country. Alternatively, and depending on the relationship you want this country to have with the rest of the world, they could execute the Samson option. 1989: A new nation. Within the Western Cape, the dislocated population of white refugees is willing to do the work that the black population once did. Those moneyed people who stayed in Africa mostly had money elsewhere in the world and once these accounts were unfrozen, these people begin the work of building the new all-white country in the tip of Africa. The black polities now forming the remainder of what was South Africa work out their way forward, or not, much as actually did happen in Congo, Rhodesia and Mozambique. [Answer] Your map is the post apartheid map of South Africa. For your scenario you should start with the map during apartheid era when all the 'homelands' were in place. The ultimate aim of Apartheid was exactly that, splitting the races and black tribes each into their own area. This, as with all social engineering schemes, was doomed to failure. 'kilisi' in his answer is correct. The South African economy was too integrated to make any split viable. Each of the 'homelands' were too small and economically poor to be successfull. The remainder of South Africa had all races working together on a daily basis but then going home to their own suburbs. The government attempted to forcibly move people to the 'correct' area but always encountered strong resistance from within and outside South Africa. Even the white minority of a few million were deeply divided politically. Only a small part of the Afrikaners would have been willing to live in a white only homeland. Some did attempt exactly that: <https://www.cnn.com/2016/12/20/africa/orania-south-africa-afrikaners/index.html> Your scenario has in fact happened to some extend. A fair proportion of the white population as well as smaller numbers of other races have moved from South Africa to establish 'mini' South Africas in countries like Australia. There are no accurate figures on the numbers that have left. [Answer] That was already intended in our timeline: the split parts for each racial group were called [bantustans](https://en.wikipedia.org/wiki/Bantustan) and were supposed to become sovereign states different from South Africa, which would have remained as the white part. Here is a map of bantustans in South Africa and Namibia ([credit user DrRandomFactor from Wikimedia Commons](https://commons.wikimedia.org/wiki/File:South_Africa_%26_South_West_Africa_Bantustans_Map.svg)). It can be seen that boundaries don't seem fair, but they weren't intended to be fair. However, the problem of keeping diamond mines in white hands - pointed by other answers - was solved. The problem of labor needed in white cities was also addressed by allowing black (now foreign) workers commute from their bantustans. [![Map of Bantustans](https://i.stack.imgur.com/sj2cb.png)](https://i.stack.imgur.com/sj2cb.png) [Answer] Disclaimer: I'm not a historian. Lots of hand-waving happens to make this work. I also believe that xenophobia, racism and bigotry makes countries weaker. The only way South Africa could have successfully split among racial lines would be if whites could get rid of the need for cheap labor, either through automation, or having more financial resources, or both. ## Background A very large share of South Africa's GDP is from mining, especially gold and diamond mining, but the mines are largely owned by British foreign interests. Another large part is the export of food, especially corn grown in Kwazulu-Natal. ## The alternate history If the British hadn't won the second Anglo-Boer war (which was partially motivated by newly discovered mineral resources in South Africa), it's possible that the two independent states of the Orange Free State and the Transvaal ([map](https://en.wikipedia.org/wiki/Second_Boer_War#/media/File:South_Africa_late19thC_map.png)) would have merged and kept control of the vast mineral wealth of South Africa. They would need to conquer Natal to gain access to a port. Thus forms the Boer Free Republic (BFR). Given their long enmity with the British empire, the BFR may have allied with the German colony in [German South West Africa](https://en.wikipedia.org/wiki/German_South_West_Africa) during the first world war. Given the established alliances, and South Africa's [strong ties with Japan](https://en.wikipedia.org/wiki/Japan%E2%80%93South_Africa_relations), and obvious ideological similarities, the BFR may have allied with the Axis powers during the Second World War. Whether that war was won or lost, if the Boer Free Republic retained it's independence due to successes in that war, many German engineers and scientists may choose to flee to the BFR. It's at that point where the gradual rebuilding and development of those countries after the war, and the realization that long-term dependence on black labor is untenable, that the search of a technological solution to the labor problem starts. Utilizing the knowledge of German engineering and the Japanese automation revolution, South Africa largely automates mining, and improves agricultural automation. Through the further careful choice of less labor-intensive crops, they manage to gradually free itself of the need of black labor. They start deporting workers to the Cape. ## A real-world aside Orania had this exact problem, and developed nut-harvesting technology to obviate the need for labor intensive nut-picking. (They built machines that shake the nut trees and catch the nuts. It's pretty nuts.) In addition, there was talk of automating mining after the recent mining strikes for higher wages. Apparently the technology to automate mining has existed for a while, but has not been the most economical option. [Answer] The South Africa of today has an economy that is based to a great degree on exports to neighboring countries. That means South Africa being the "most industrialized" nation in Africa exports goods and services to countries that no longer can internally support those demands either because of war, poverty, deindustrialization or underdevelopment. So splitting on racial lines would invite all kinds of sanctions and effectively ruin the economy the white population depends on. It's probably why as one poster above said, the NP (National Party) was backed into a corner and had to accept democracy in 1994 to ensure its own survival effectively making it impossible for segregation to exist today or in the future. [Answer] It isn't possible to do on a large regional basis. I was curious about the diversity of South Africa at one point last year and calculated the percentage of each ethnic group in every Province. Every Province has a majority Black or Black/Coloured population. Whites are most numerous in Western Cape (Cape Town) at 15.70% and Gauteng (Johannesburg) at 19.10%. Black Africans are the majority nationwide. The other option which already happened was Apartheid, which was of course completely evil. ]
[Question] [ 3D printing technology has come of age, its application is widespread and has already started to replace many manufacturing processes. Let us cut to the chase: I am wondering if we can really print anything under the Sun. If not, what kind of inorganic tool will never be 3D printed? (Set in the present day and every component must be printed according to design intent) [Answer] # Crystals / anything made out of crystalline material 3D printing is pretty much just a fancy way of doing [sintering](https://en.wikipedia.org/wiki/Sintering) or precision melting/re-solidification. That instantly precludes some things. [Crystals](https://en.wikipedia.org/wiki/Crystal) for instance are ordered down to the atomic level. This can never be made with sintering or smelting. Also some crystals require very high pressure to form, pressures that would make it impossible to let a 3D printer do its job. [Answer] In general, materials which require extreme production conditions, or devices require great levels of detail to function, could never be produced by a 3D printer. These include: * Computer chips (the transistors are far to small to be printed; it takes hundreds of steps to make a computer chip and the only reason they don't cost millions per chip is because we produce them in batches of thousands). * Components made of metal alloys with very high melting points (the printer wouldn't be able to melt them to print them) * Crystals such as diamond, which require enormous amounts of pressure to form. In addition, I believe that it will always be cheaper and easier to mass-produce some things with specialized machines than with a 3D printer. If you have a very specific job that needs doing, a tool designed specifically for that job will almost always work better than a generic tool made to handle a wide range of jobs. That said, 3D printers can greatly accelerate the design process, and there will be many instances where it's easier or cheaper just to 3D print a medium-quality product, as opposed to purchasing the highest-quality version. [Answer] Chisels, saws, axes, and knives; basically any cutting tool. That is, [anything with spring steel](https://en.wikipedia.org/wiki/Spring_steel#Applications), they all require heat treating. You would be surprised how many things have springs in them. Honestly, anything that cannot be made of cast steel cannot be made with a printer. [Answer] Long fibers or anything that requires unified process. Some properties cannot be gained with an additional manufacturing steps. Nowadays only metal and plastic can be printed. It is more often about feasibility. You could add one metal atom at a time, but it would take for ever to print something not nano-scaled. Also there is price, speed etc. [Answer] The question is not whether you can, it's whether you should. It's unlikely that there will be anything that is truly impossible to make using something that can be defined as 3D printing - but there will be many things that will never be economically viable to make in that way. Generally, the simpler and stronger an item needs to be, the less point there is in printing it. So maybe you could 3D print a hammer, but it'd make much more sense to make it in the usual way. ]
[Question] [ In the moment I am writing a story about a post apocalyptic earth where a new, stable society is thriving centuries later. The setting is planned to be an early industrial solar punk world with some futuristic elements due to the fantastical event that caused the apocalypse in the first place. My question is, what needs to happen physics wise, be it changes in laws of physics or supernaturally, for nuclear weapons, new and old, to not work in the first place without changing the makeup of the world and/or universe drastically? I am looking for a solution that works physics wise even if the why it happens is handwaved. Edit: My question was a bit vague. What I want to know what laws of physics need to change to make nuclear weapons stop working, preferably atom wise, without changing reality drastically. With magic I meant to inform that the why of it happening could be through magic. There is no need to explain what the magic could be, only how the physics part works. --- Note: An [earlier question asked how to counter nukes with technology](https://worldbuilding.stackexchange.com/questions/156096/how-to-make-nukes-useless). Please note the tags here, I am changing physics to prevent nuclear weapons rather than designing a defense for them. [Answer] May not need magic There are a number of factors that definitely will work against having nuclear weapons in a solarpunk society centuries post-apocalypse and more factors that could make them impractical even without changing the laws of physics. 1. Disregard "old" nukes - Any nuclear weapon over a century old will not detonate, as per the answers to [this](https://worldbuilding.stackexchange.com/questions/132443/how-long-could-a-nuclear-warhead-remain-functioning-underground) question. Even nuclear weapons a decade or more old will require regular maintenance and replacement of various precisely-made components, including the explosive lenses that will suffer chemical deterioration. 2. Who makes new nukes? - Manufacturing nuclear weapons requires a major industrial effort, as witnessed by the mind-boggling size and budget of the original Manhattan Project. Even newer players who can skip all the tedious R&D required for original development still need to invest heavily and/or lean heavily on the existing nuclear power industry for raw materials - in a solarpunk world, would there be a nuclear power industry at all? For starters, uranium needs to be mined and refined. Then the U235 needs to be carefully separated out (it's only about 0.7% of all uranium) using a centrifuge. (Magic option 1 - make it impossible to separate out the U235 to sufficient purity through the existence of a [computer virus that gets into the centrifuge controllers and wrecks them](https://en.wikipedia.org/wiki/Stuxnet) any time someone tries to obtain highly enriched uranium or plutonium - magic Stuxnet on steroids. Bonus points if the virus then tells everyone where the naughty person is that's trying to make a nuke.) 3. Explosive lens fun - assuming that nuclear material can be obtained, explosives are needed to either implode an otherwise sub-critical mass (implosion weapons) or smash two sub-critical masses together (gun-type weapons). Gun-type weapons are relatively hard to mess with because they are so crude and inefficient - with plenty of fissile material and careful machining the sub-critical cylinder could be inserted into the sub-critical sphere by literally lighting a fuse to set off a propellant charge. Fortunately they require a large amount of fissile material and are also considered quite [unsafe](https://en.wikipedia.org/wiki/Nuclear_weapon_design#Gun-type). Implosion devices, however, require extremely precise machining of the explosive lenses and extremely precise timing on the detonation. (Magic option 2 - make all timing circuits in the vicinity of weapons-grade fissile material develop multi-millisecond glitches that will prevent sufficiently precise detonation for implosion devices. Make timing circuits fail completely in proximity to a total mass of fissile material sufficient for a detonation, even if it is in multiple pieces currently.) TLDR - build the "magic" into all electronics that are or can be manufactured in this world to ensure that nuclear weapons are either unable to be manufactured (by preventing isotope separation) or unable to be detonated (by preventing the firing circuits working in the vicinity of weapons grade material). This can be either "real" magic or a weakly godlike AI that has inserted its code into all machines that are used to manufacture electronic components. [Answer] (this answer is based on a dream I had. This opening allows magic, so let's put the idea...) ## How the ICBM issue was solved in the 1980's Your world is set in the future, my answer is set in the past. It can be solved. Telekinetic kids Back in the 1980's, at the time world wide nuclear destruction seemed to be around the corner, millions of youth and their parents hit the street, to protest against nuclear arms. Back then, we felt empowered against the seemingly inevitable destruction of the planet. Many children joined these protests, also the ones who were developing a new talent, later recognized as long range telekinesis. There has been a limited amount of publications, but at the time, there were many skeptics, who framed these children as superman-wannabees. What they did not know is E.R. Pelinant, a Hungarian physician who fled to the West in 1956, seriously researched these children and measured their abilities. He made an inventory and founded a secret international research organization, that set out to train long range telekinetic abilities. Pelinant's idea was to use telekinetic talents to cause ICBM's to deviate from their path slightly.. preventing cities from being hit. Website The talent was very rare, and remains rare today. In a large city like Hong Kong, there existed only 20-25 children able to move objects at a distance. Some of these children could move heavy objects, from very long distances. Pelinant set out to test their capabilities, and made a list.. but he could not devise an early warning system for it. But he did keep in touch, and tried to keep track of where they live. The early talents are in their 40s now and their number has grown considerably. When internet and cell phones arrived in the 90's, Pelinant set up his web site, which today still exists. The address of this web site is kept secret, to prevent superpowers from hacking it. Pelinant rejected a secret Nobel Prize in 2002. Worldwide, the society has more than 6000 capable and motivated members. It has hundreds of professionals, military and non-military, helping them to gather information. There is a map on Pelinant's website, showing locations and projectile paths in real time. Of course, no large scale nuclear conflict ever started.. Pelinant's system was never tested sofar.. but the members spend a lot of free time to study the maps and practice. Some members are activists against all military. They regularly cause military satellites to get lost in orbit, or cause F16 forced landings. To practice, or just for fun.. Swipe it off course A telekinetic talent in San Francisco recently curved one of Kim Jong Un's missiles into the Pacific, preventing it from hitting a Japanese coral reef. Nowadays, telekinetic folks have a perfect app for this.. when an alarm reaches their cell phone, they get a map and help "swipe" the missile off track. [Answer] No changes are required. Imagine if the apocaliptic event was predicted, and mankind tried to survive it. They build generation ships and stocked them with as much nuclear material they could get their hands on to power and propel them, including some Orion Drives (detonate a nuclear bomb at the right spot to propel the ship). What nuclear material that remained was used to power the bunkers and other survival equipment for decades and centuries. There is simply not enough fissible material left. What fissible material is left cannot be reached for centuries since the higher tech civilization would have mined it. Naturally when leaving the predecessor civilization realized the problems of leaving a world without much gas/oil/nuclear resources so they left renewable technologies with those who stayed behind, chief amongst the surviving technologies being solar panels&solar panel fabrication for your solar punk. Edit: you dont have to take that exact scenario ofcourse. It doesnt matter if some lunatic managed to send all nuclear material into the sun, its all been used or its all hidden somewhere by the pre-apocalipsers. What matters is that there is simply not enough available for building nukes, or at least to test and build enough large nukes to change your setting. [Answer] # Magically change a few first principles It's a blessing that you chose not to put the hard-science or science-based tags in a question asking to break fusion bombs without breaking reality. Many stars will become vocally upset at what you are about to do, so handling this with the magic tag was a wise choice. Now, magic can safely put a bubble around planet earth that contains our new laws of physics without ripping spacetime asunder. Shields up? Good. We're going in the opposite direction of @Phillipp, because I don't think rapidly reducing the critical mass of every known isotope will stop bomb makers the way you intend. There will be no more bombs being made, I promise you that. Because there will be no one to make them after you cook the universe. I will draw my answer here [from a similar question I posted](https://worldbuilding.stackexchange.com/questions/159409/which-of-these-changes-to-physics-will-have-the-least-effect-on-earth-s-biology) asking to change the fundamental laws of physics. You need only to rewrite some of the fundamental principles of the metals in the actinide series. And since this experiment is happening in a little bubble around earth, you really only need to worry about some uranium, thorium, and plutonium, since those are the only elements we have in sufficient quantities on earth to talk about regarding atomic weapons. I say atomic weapons specifically, and not thermonuclear weapons, because thermonuclear weapons need atomic bombs to fire them off anyway. Kill the atomic bomb, and you kill all practical and semi-portable means of making atoms go boom on this planet. Technically, if you want perfect and absolute nullification there are 15 actinides which can initiate the big boom. I will only talk about making them practically impossible, because you're not going to get enough lawrencium or fermium to do anything dangerous. The boom you want to stop comes from neutrons, and neutrons come from atoms that are unstable. That's a colorful name to describe atoms which are not eternal, like most of the ones we know and love. In fact, the actinide series, as it is called, has that name because there is literally no stable element in that block of elements: they are all "radioactive". At some point, all of them will die, falling apart and shooting off some particles. There will be a point some time far down the road that practically no actinides exist at all on earth or the universe, save for what the stars are making now. Why are actinides special in making a big boom? It's not far off to call it magic, it is essentially just the way the universe was written. Radioactive decay is what is known in physics as a spontaneous event. It means something which causes itself, and no forces or qualities outside the atom can cause it, change it in any way, or stop it from happening. Causality tracks causes and effects by a "light cone," respecting the speed of light in cause-effect relationships. Nothing the universe can do, will cause something else to happen faster than the speed of light. But radioisotopes can ignore this rule becuase they simply have no cause. They just obey their half-life rules absolutley. It just is, and our universe is so much more wonderful and predictable for that (especially science). Let's look at the very wonderful tool of carbon dating that is only possible because of this spontaneous event, for example. For carbon dating, we use carbon-14. Here is the decay chain for it: $$^{14}\_6 \text{C} \rightarrow \_7^{14}\text{N} + \text e^- + \overline{v}\_e : \lambda = 5,730 \text{years} $$ OK, yes, this is Greek. All you need to know is that any atom of carbon with a six protons and eight neutrons in its nucleus is going to be turning into nitrogen some day, weather it likes it or not. When this will happen is impossible to predict. it is not random, and it is not triggered or caused by anything outside. What we know is simply, that 5,730 years from today, half of all the carbon 14 in the universe today will have turned into nitrogen. Then, in another 5,730 years, half of that remaining carbon 14 will be nitrogen. And so on, forever, never reaching zero. It is a real-world (and true) example of Zeno's [dichotomy paradox](https://plato.stanford.edu/entries/paradox-zeno/). Why this is such a great benefit to us, is that it is an absolute reference. We don't need to think about how old the carbon 14 is, or how hot it is, or anything about the pressure. The universe guarantees us absolutely, that it will erase half of it's inventory of carbon 14 in the that amount of time. So with a simple count of this atom in the bones of the fossil, we know exactly when the thing being tested stopped eating forever. Now, there is no need to worry, stars are making more of it all the time. This is why earth is inside a magic bubble, because you are going to just change some of these numbers that never had any rhyme or reason to begin with. Let's start with the most readily available actinide, uranium. The uranium we use in bombs is $^{235}\_{92}$U, but we won't play with that just now. What we want to change to neutralize a bomb is the $^{236}\_{92}$U that is formed when one of those U-235 atoms picks up a stray neutron to turn it into U-236. Most atoms are pretty happy having an extra neutron, and they just check their schedule to see if they are now stable or not. If not, they wait for their magical clock to strike, and then decay as intended. But $^{236}\_{92}$U is what is called a fissionable material. Don't ask why, there is no why. These are just the way atoms work. A fissionable material is an atom nucleus that can be split into two or more pieces by being hit by a neutron, instead of just absorbing it. For example, Actinium-236 is made by smacking Actinium-235 with another neutron. The new atom will hang around for a while, and half of them will decay in about 70 seconds. Then another half of what's left in 70 more, then another half of those leftovers (1/8 of what you started with), and it goes on. But, the actinium-236 won't split apart, even though it's the exact same size as uranium-236. There is no why, and that makes your problem much easier. If $^{236}\_{92}$U were a happy little atom like its neighbor actinium, it would not split in two 80% of the time it got hit. This splitting is where the energy comes from to make the boom. But, nearly 20% of the time, uranium-236 does follow it's decay schedule properly. That looks like this: $$^{236}\_{92} \text{U} \rightarrow \_{90}^{232}\text{Th} + \alpha : \lambda = 2.37005 \times 10^7 \text{years} $$ Now you see, if you could make this U-236 atom happy like actinium is, then it would not undergo fission. It would wait around for its time and in 27 thousand years, half of them will have turned to thorium just like the formula above. It makes for a very slow boom that most civilizations would have time to pack there bags and move to another star system before knowing about it. It really is that simple: By decree, U-236 now decays into thorium 100% of the time, like all other well-behaved atoms. You have just broken almost all current nuclear weapons, and nothing on earth breaks. Your story doesn't need an explanation‚Äîit can't have one. There is no cause for atoms being fissionable to begin with, so whatever scientific "mumbo jumbo" you invent to explain "why" U-236 works differently is just more magic you need to explain. OK, ${236}\_{92} \text{U}$ is only one problem child in the angry fissionable group. You need to deal with plutonium 240 as well, because that is spontaneously fissionable. Some thorium and americium isotopes will need to be tamed to really shut down mad bombers. but to guarantee earth has no nuclear bombs, just make all fifteen actinide elements magically non-fissionable, which means you just undo the magic that made them fissionable to begin with. And do keep that bubble up like I did in my problem. Bad things will happen in stars if you don't. [Answer] Cosmic horrors [![enter image description here](https://i.stack.imgur.com/ZeACP.jpg)](https://i.stack.imgur.com/ZeACP.jpg) Humankind was ignorant to the true depths of their hubris when splitting the atom. The alpha and beta particles cast into space by early experiments created a beacon whose strength only intensified as experimentation turned into an industry. Ripples in existence began to be detected by astronomers. At first they were understood as gravitational waves, but as their intensity grew, it became clear... Einstein was a harbinger priest of that which can only be pronounced by human tongues as Cthulu. Global leadership united to pool all nuclear resources into a teleporter that would move the planet to a new star system before The Arrival occurred. Once again undetectable in the cosmos, humankind swore to never again light the beacon. [Answer] # Alternate History: No Manhattan Project While the discovery of the theory of nuclear power and weapons was inevitable, their actual implementation was not. With some slight changes to history, you can make it so they remained theoretical. Actually building nuclear weapons requires a colossal and expensive investment in engineering and infrastructure for the weapon and even more to produce the fissile material. The US undertook this cost in WW2, [The Manhattan Project](https://en.wikipedia.org/wiki/Manhattan_Project#Cost) was one of the most expensive projects of the war. Those resources could have been used elsewhere. What if it didn't happen? To oversimplify it, the Manhattan Project happened because the US thought [the Germans were building a bomb](https://en.wikipedia.org/wiki/German_nuclear_weapons_program). Which they were, however the Germans grossly underestimated what would be involved in a practical nuclear bomb program and never came close. [Allied sabotage](https://en.wikipedia.org/wiki/Norwegian_heavy_water_sabotage) didn't help. In this alternate history, the reaction to the [Einstein-Szli√°rd letter](https://en.wikipedia.org/wiki/Einstein%E2%80%93Szil%C3%A1rd_letter) warning about the German nuclear program is muted. Rather than creating their own nuclear program, the Allies decide to wait and see and hamper the German program. The war in Europe ends with no nuclear program. The [Soviet Invasion of Manchuria](https://en.wikipedia.org/wiki/Soviet_invasion_of_Manchuria), non-stop conventional bombing, and the threat of the revolt of a blockaded, starving population causes Emperor Hirohito to capitulate in Fall 1945. With the war over, the US slashes its defense budget. The US is rich with oil and coal and has a huge surplus military, it has no reason to spend colossal amounts of money on nuclear power and weapons. Europe and the Soviets are rebuilding, they have better things to spend money on. Fission remains like fusion today: always 10-20 years away, always underfunded. While nuclear power may eventually be successful, it won't come to be in the heady context of a post-WW2 anti-Soviet paranoia with an unlimited, secret military budget. It would come from commercial and scientific endeavors. Huge stockpiles of nuclear weapons would not be integrated into national defense plans, nor to counter the other guy's huge stockpile of nuclear weapons. Rather than being seen as a necessary evil and measure of national prestige, they would be seen as an unthinkable weapon of mass destruction like chemical and biological weapons are today. Some nations might keep small stockpiles, but it would be nothing like the massive glut we have today. [Answer] # Depends on the time scale All nuclear weapons use the fission of radioactive heavy elements to produce the bang. Well, these elements have half lives over which 50% of the radioactive materials decay, typically to more stable elements, reducing potency. With enough time, all these materials become scarce. Plutonium-239 halflife is 24 thousand years. Uranium-235 halflife being about 700 million years. That's not to say something couldn't happen to drastically shorten that time. For each period that occurs though, 50% of the existing material is gone. If Magic was to specifically target atoms of this weight and isotope, throughout the universe, not much else would change, other than the addition of the byproducts of the decay. Right now there isn't enough plutonium-239 easily reachable to us to make weapons so we collect it as a waste product in nuclear reactors, then use that to make plutonium bombs. TL;DR the base material components can decay to where we don't have the materials required, and those already in existence essentially go stale and no longer work. [Answer] ## Neutrino lasers and detectors Neutrinos take part in many nuclear reactions. As they are almost (but not quite) massless, and pass straight through the Earth without interacting most of the time, we usually ignore them. Nonetheless, the idea that neutrinos could affect the rate of radioactive decay, even on Earth, has been discussed seriously enough to [make news](https://science.slashdot.org/story/10/08/26/1749232/Follow-Up-On-Solar-Neutrinos-and-Radioactive-Decay), even if it is probably balderdash at the levels we normally encounter. Your civilization has discovered how to interact normal matter with neutrinos effectively! As a result, you can do two very significant things: * You can visualize all of the radioactive material emitting neutrinos everywhere in the world. There's no bunker deep enough, no satellite high enough to keep you from seeing the lump of concentrated nuclear material inside. * You can create intense beams of neutrinos. (Calling it a "laser" may be an abuse, but it is at least tightly collimated) These beams are powerful enough to reduce the critical mass of an isotope by a large factor. That means that a nuclear bomb with a sphere or gun of uranium waiting to be put together can now be set off by anyone with a neutrino laser, whenever they want. Even if you make a lump too small for you to set off with the laser ... someone else could make a bigger laser at any time and set it off in your own bunker. This doesn't completely eliminate the possibility of nuclear attack, but what remains is not very satisfactory. For example, a group of people could carry tiny lumps of a fissible element and throw them all together in a pot for a beam to sweep into and set off. Designing an elegant bomb is no longer needed because the beam itself can trigger an abrupt explosion. However, such methods tend to be suicidal because it is hard to clear to a safe distance before the site is attacked with conventional weapons, and the people smuggling even tiny lumps of isotope will still probably be found and stopped in advance unless there is much chaos already. The explosion produced will likely be small, more "tactical" than "strategic". Enough to remind people the option is out there, but not enough to make it a winning plan. [Answer] First, as others have noted, old nuclear weapons do not work without constant maintenance. Especially, but not limited to, the fissile cores. Secondly, you do not get to have nuclear weapons blipped from the playing field without losing nuclear power (fission) entirely. The processes are similar enough that I can't think of anything that would remove the former without also removing the latter. If the cross sections could somehow change so that the nuclear chain reaction doesn't support explosives, it looks as if you can't do traditional (or even any) reactors at all. Likewise if you start messing with the speed of the neutrons themselves. So, with those caveats out of the way, what you need is a subtle change in the weak force. Something that drastically alters the decay so that it is unsuitable for nuclear weapons, and there are maybe as many as 5 or 6 isotopes that similar changes have to occur for. For instance, a suitably altered weak force can reduce the output of neutrons to the point that no chain reaction can be sustained. The decay chain of the isotope changes slightly (I have no idea if you'd want to live in a house with a basement with high radon or not in such a universe), and you might even alter the rate of neutron capture (when instead of splitting, you get U236). Done correctly, and you still even get to do things like carbon-dating for archaeology. Done poorly, and orthodox chemistry becomes a figment of imagination and all life in the universe ceases to exist. This change might be done locally, so that aliens millions of light years away still get to nuke each other but your planet is safe. But it's unclear if that's pseudoscience or not... changes to fundamental constants are still assumed to be universal. Though if you're changing them at all we're pretty far into lala land territory, so what's a little extra pseudoscience? [Answer] ## Greatly accelerated radioactive decay. When radioactive elements decay a lot faster in your world, then any fissile isotopes on Earth would soon decay into stable isotopes. So there would be nothing available to build nuclear bombs with. When this happened in the distant past, then Earth would be largely look the same as it does today, minus nuclear technology. All the basic building blocks of the planet and its ecosystem are based on stable elements. Radioactive elements don't play an important role on Earth, neither biological nor structurally. When this change happened in the recent past, then it could very well be the reason for the apocalypse. The reason is that radioactive decay implies decay radiation and decay heat. * The fuel rods in all the nuclear reactors would suddenly become a lot more reactive. All nuclear power plants around the world would simultaneously have meltdowns. Their safety measures would probably fail, because they weren't designed to anticipate a scenario which was considered physically impossible. * Accelerated radioactive decay would mean that any stockpiles of radioactive isotopes (both nuclear weapons and civil nuclear fuel) would suddenly become very hot and create a lot more radiation. Their casings would melt and their radiation would escape freely. * Radioactive ores in Earth's crust would suddenly become hot and very brittle, leading to earthquakes and volcanoes (radioactive volcanoes!). All of this could probably kill a lot of people and cause the collapse of human civilization. But this apocalypse would be rather short-lived, because the higher the intensity of the radiation of a decaying isotope, the shorter its half-life time. And because this apocalypse would be associated with all nuclear power becoming simultaneously dangerous and unusable, it makes the transition to a new solarpunk civilization even more plausible. [Answer] I'm going to interpret the prompt of "nuclear weapons not working" to mean that they can't be built or used as weapons. Making nuclear physics not function at all has too many side effects. In your pre-apocalypse world, large-scale nuclear war was an imminent threat. One of the factions in that world created a space-based, fully automated nuclear weapon detection and neutralization system. This system has a constellation of satellites that can detect the radiation emitted by any non-trivial quantity of nuclear fuel. Once the location is pinpointed, an orbiting platform will use a laser, kinetic bombardment, or <insert weapon here> to destroy said radioactive object. This defense system made nuclear weapons unusable. If a military built a nuclear warhead, the defense satellites would attack it within seconds. The weapon would detonate and destroy whoever was trying to use it. Any remaining warheads would be stored in deep underground bunkers. Attempting to bring one to the surface would result in the warhead (and anyone nearby) being destroyed almost instantly. The system runs completely on autopilot at this point, the ground stations used to control them long gone. Your people are far from technologically advanced enough to disable or destroy the system, perhaps not even advanced enough to understand or see the system. For now, it's as if some unseen magical force will smite anyone foolish enough to try to build or retrieve one of those terrible weapons of old. The drawback is that this would largely preclude the use of nuclear power as well. Naturally-occurring deposits of radioactive material won't be affected. The defense satellites are smart enough to differentiate between slow changes in radioactivity caused by geology and the relatively fast changes caused by fuel refinement, artificial fission, etc. [Answer] The Advent of Weapons with Greater Potential While quite obvious, and perhaps not the answer you are looking for, more powerful weapons would nullify the use of nuclear weapons, especially if they replace the purpose of nuclear weapons(MAD etc.) , and be significantly more powerful than the nukes. This would not solve any problems that are related to the existence of nukes, but merely make it so the power of the Greater Weapon is not based on the properties of the nucleus of an atom, but instead some more powerful source, perhaps antimatter, in a controlled and concentrated setting, which I don't think is possible even theoretically, or some sort of quantum disturbance, that erases the Enemies of the Nation from time itself. As long as any replacement fulfills at the idea of MAD, and does it in every way possible better than a nuclear arsenal, for example no wait time between press of button and impact would be a big plus, than nuclear technology would be forever obsolete, in a way that the AK-47 isn't, because any nation still using them would not receive any benefit, since they would be destroyed before impact of their now obsolete rocketry. In particular I propose the idea of instantaneous destruction, as it most clearly and cleanly replaces the nukes, giving them no power. [Answer] Do you need it to be our Earth? Because, other (probably perfectly habitable planets) may be poor on Uranium and Thorium (and probably also poor on other elements, see the table) Table: <https://en.wikipedia.org/wiki/R-process#/media/File:Nucleosynthesis_periodic_table.svg> (just remove or decrease the violet-colored parts for an image what to expect) No (or pretty much scarce) natural Uranium and Thorium means no nuclear era until the development of fusion reactors and no bombs (at all). [Answer] Fission catalyst (handwavium) particles It was discovered that by operating a particle accelerator in a particular way, it could be used to generate a beam of Foo particles. (Strangelets? Dark matter? Make it up). These are weakly interacting with normal matter, so they will go through atmosphere or tens of metres of rock without getting absorbed much. However, they act as a catalyst on unstable nuclei, reducing their half-lives by several orders of magnitude. A nuclear weapon has to contain a high concentration of unstable nuclei. When hit by a beam of these things, the nuclear materials start decaying with a half-life of days, rather than large numbers of years. The bomb becomes very hot and melts. Not as a useful explosion, just as a fizzle, with its explosives spreading the mess like a mini-Chernobyl. Instantly, nuclear weapons (and of course nuclear power) have to be abandoned, because the means now exists to make nuclear weapons (and atomic power stations) melt into radioactive slag wherever they might be constructed. Any enriched Uranium (or heaven forbid, Plutonium) has to be buried very deep where such a meltdown won't do any harm. Or quite possibly, diluted in solution and then dumped into the Marianas trench to get very much more diluted in a part of the ocean that we don't really care about. So there we are. A world without nuclear bombs or nuclear power stations. You may have noticed that a beam of these particles might also be a ray-gun that works. Everything contains low concentations of unstable nuclei. Being hit by this beam might be like being hit by a small shell, except that a concrete fortification won't save you. You might like to have ray-guns (large, heavy and expensive enough that they don't instantly destroy civilisation.). Otherwise, make the effect mediated by concentration. If its not a macroscopic concentration of nuclear instability (grams or kilograms), the catalytic effect is negligible, so the effect on living organisms is negligible. This might just something we haven't discovered yet. Very unlikely, but plenty good enough for a McGuffin. (In real life, muons will catalyze nuclear fusion of Deuterium. It's just a shame that we cannot make muons efficiently enough to get fusion power! ) [Answer] ## The key lies in your reliance purely on solar power Making a nuke requires 2 things that a solar society may not have: an advanced understanding of petrochemical compounds required to make the very precise high explosives you need to trigger a Nuke, and the existence of large scale hydro-electric dams capable of filtering the VAST amounts of water you need to get enough heavy water to make one. Also, there are certain kinds of contamination that can make a river unviable for heavy water refinement. So its also possible that the apocalypses simply contaminated your water sources badly enough with the wrong stuff that refinement is no longer viable even if you do still have the large scale dams to do it with. I do not know what these contaminants are, but it is a known fact that the USA now relies on other countries for heavy water due to contamination of its historical heavy water sites. [Answer] ### Telekinetically-accelerated decay of nuclear weapons No object in the world is as incredibly fragile and produces as much fear as a nuclear weapon. As we all know, research into paranormal abilities was at its peak during the Cold War, as the United States and Russia were constantly looking for ways to undermine each other. As we also all know, these programs were complete failures. Nobody actually managed to create or discover anything resembling a useful telepath or telekinetic during this period and the program was dropped, since psychic abilities were obviously not real. At least, that's what everyone thought. In reality, the programs did successfully produce several telekinetics - but nobody discovered them for several reasons. First, telekinesis is subtle. You're not going to get things like floating objects or mind control - the most you could hope for is a slight adjustment of probabilities. Second, telekinesis is slow. You're not going to see any effect during the duration of a test - but stress and powerful emotions over long-term periods can lead to subtle changes in reality. Third, the range for telekinesis is, for all intents and purposes, infinite. Since both sides of the Cold War were aiming to produce psychic weapons, their efforts were constantly undermining each other, and the net output of both programs - insofar as undermining each other is concerned - effectively balanced out. Nobody was going to discover anything because the other side was trying their hardest to make sure their enemies didn't discover anything. However... The fear of nuclear war and mutually-assured destruction was on everyone's mind, and this included the psychics. When the programs ended and the experimented-on children were released, they continued to project a subtle field over many, many years - a subtle field that was centered on the source of their fear, the bombs themselves. Natural telekinetics all over the world were likewise unconsciously projecting a subtle field that was doing all it could to break down the nuclear weapons. Nuclear weapons are some of the most fragile objects in the world - a slight change in their structure will cause them to fail. This makes them perfect targets for the subtle psychic pressure of telekinetics around the world, and makes them much more likely to break down over time than anyone would have guessed. When the time comes to use them, they all turn out to be duds. ]
[Question] [ In [a previous question](https://worldbuilding.stackexchange.com/questions/107627/how-can-mutually-assured-destruction-be-made-not-assured) I asked how Mutually Assured Destruction could be made not assured. Most of the highly rated answers focused on political methods, but [one answer](https://worldbuilding.stackexchange.com/a/107765/35695) raised the possibility that Kessler Syndrome might make ICBMs impracticable - it's this idea that I'd like to test for practicality. *Given the Earth, with present day technology, is it technically feasible* to fill LEO with enough stuff that any ICBMs fired will have only a small chance (let's define it as 5%) of making it to their target?** For the purposes of this question I'm not really interested in economics or politics - feel free to assume that the entire industrial output of the Earth goes towards achieving this, and that world peace magically breaks out for as long as it takes - I want to know if it's possible from an engineering and physics perspective. I've tagged this as [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") instead of [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") because it's likely to require a bit of [XKCD What If?](https://what-if.xkcd.com/146/)-type guesswork, but I'd like to see answers that include calculations and that are based on empirical evidence. [Answer] # Not possible ### TL;DR In order to ensure that an ICBM had only a 5% chance of surviving for 20 minutes in space, you need to launch at least 5 orders of magnitude more mass into space than has been launched since Sputnik. This is not economically feasible, so Kessler syndrome cannot protect you from ICBMs. ### A note on ICBMs First we have to define what an [ICBM](https://en.wikipedia.org/wiki/Intercontinental_ballistic_missile#Flight_phases) is going to do. It travels a ballistic course, up to 1200 km altitude, and it can be launched from any latitude. This part is important; a sub-launched missile from the North Pacific can hit Moscow while never travelling below the 50th parallel north. ### What is the collision frequency of orbital objects? From the original paper, [Kessler and Cour-Palais, 1976](http://www.castor2.ca/07_News/headline_010216_files/Kessler_Collision_Frequency_1978.pdf), the collision rate for a single object in orbit is $$ \frac{dI}{dt} = S\bar{V}\_sA\_c,$$ where $I$ is the cumulative number of impacts, $S$ is the spatial density of particles in orbit in km$^{-1}$, $\bar{V}\_s = 7 \text{km/s}$ is the relative impact velocity (calculated in the paper), and $A\_c$ is the cross-sectional are of the object in question. Generously counting the third-stage booster, a modern [Trident II missile](https://en.wikipedia.org/wiki/UGM-133_Trident_II#Additional_specifications) has a 7 foot diameter and is about 12 feet long. Lets use a 7x12 foot surface as cross sectional area, which works out to $8\times10^{-6}$ km$^2$ to match units. This gives us an equation: $$ \frac{dI}{dt} = 5.6\times10^{-5} S$$ where we will solve for $S$ in units of particles per cubic kilometer and $dI/dt$ in collisions per second. ### What collision rate leads to a 5% survival rate for an ICBM? A Poisson distribution gives the number of discrete events in a certain time period, based on a rate function, the probability that the event will happen. The probability mass function for the [Poisson distribution](https://en.wikipedia.org/wiki/Poisson_distribution) is $$P = \frac{\lambda^k e^{-\lambda}}{k!}.$$ $P$ is the probability that an event will happen, $\lambda$ is the rate of an event happening, which is what we will solve for, and $k$ is the number of events. We want to solve for $P = 0.05$ and $k=0$; that is, there is a 5% chance that there will be zero collisions. Plugging these in, we solve for $\lambda=3.00$. For our Trident missile, let us assume 20 minutes (1200 s) are spent in the orbital regions of space. Therefore $\lambda$ is in units of events per 1200 seconds. Converting to units of events per second, we get $\lambda = 0.0025$. This number is equivalent to the $dI/dt$ that we want. ### How much space do we need to fill with particles? Mentioned in the introductory note is the point that ICBMs can get into all sorts of unusual parts of space, because they are sub-orbital. They can fly right across the north pole. Orbits that take our anti-ICBM particles into high latitudes will also inevitably cross the equator, where there will also be anti-ICBM particles that are orbiting at low latitude. Thus, there will be a distribution of satellite orbits that peaks at the equator and reduces in density near the poles. I'm going to ignore that; instead I'm just going to say we need a constant density debris field over the Earth. We'll see why in a minute. In order to have a good chance of stopping an ICBM, we need density $S$ of particles in all parts of space that an ICBM might reach over its 20 minute stay. This is a shell from 300km to 1200km from the surface of the Earth, or at a radius of 6670 to 7570 km. $$ V = \frac{4}{3}\pi(7570)^3 - \frac{4}{3}\pi(6670)^3 = 5.7\times10^{11} \text{ km}^3.$$ ### How much mass of particles do we need? Plugging $dI/dt$ into our collision rate equation, we get S = 44.6 objects per cubic kilometer of space. Multiply this by the space we need to fill and we need 25 trillion particles. As you can see, increasing the particle density near the equator is not really necessary; this is plenty of ball bearings to launch. Generously assuming a 100g particle can kill a ballistic missile (doubtful!), we need to put 2.5 trillion kg of particulate mass into orbit to allow only a 5% chance of an ICBM to get through. The total amount of spacecraft launched since the dawn of the space age is [roughly 13 million kg](https://space.stackexchange.com/questions/88/what-is-the-total-mass-sent-into-orbit-over-all-history). # Conclusion Kessler syndrome is dangerous on the timescale of weeks and months. Once there are enough particles, your spacecraft won't last out a year, and then it is hard to justify launching something into orbit. But the particle density required to stop an ICBM, with a fast, suborbital path through space is immense. Especially with mobile ICBM platforms (i.e. submarines) nearly any trajectory for a ballistic missile is possible, so you would have to cover everything to be safe. Even dropping the requirement to a 50% kill-rate and redoing all the calculations only drops the mass requirement by a factor of about four. You still need roughly five orders of magnitude more mass in space than has been put there in the past 50+ years to form an effective defense. Kessler syndrome cannot effectively guard against ballistic missiles. [Answer] Given the awesome destructive power of nukes, a 5% survival rate isn't an effective defense, because just one warhead getting through will take out an entire city. (Even an authoritarian government isn't going to be happy about trading away entire cities at a stroke, particularly since you can't effectively counterstrike--the same space junk that blocks the other side's warheads will block yours just as effectively.) You need something more like a 5% chance of even one warhead slipping through; if the attack contains (say) 5000 warheads, that requires a survival rate of 0.01%. The Kessler effect just isn't going to give you that kind of shield. [Answer] ## Possibly, with a Slight Change The suggestion as written will not work, for two main reasons: a) Near Earth Space is just too big, as kingledion outlines in his excellent answer. b) LEO orbits are affected by atmospheric drag, so the debris field will rapidly de-orbit itself. ## The Change Use "smart debris" instead of "dumb debris". Launch a series of satellites in much higher - and therefore more stable - orbits. These satellites use radar / IR / whatever other sensors make sense. On detecting anything in LEO or that looks likely to enter LEO, they perform a kinetic attack. This is basically the Star Wars plan from the Reagan years, but completely automated, and utterly denying space access to all nations, including the launching nation. This lack of command and control should make it much simpler to implement. For bonus points, rival powers can contribute satellites to the system, so there is no worry about a "back door" that will allow one states weapons to get through. [Answer] It is possible but difficult. For commercial or even military spaceflight, it is usually unacceptable if one mission in twenty fails within the first half hour. What you are calling for is that nineteen missions in twenty fail within the first half hour. The amount of debris that would be required would be awesome. Assume that each piece of debris has an independent chance to hit a missile. To go from a 95% survival rate to a 5% survival rate, you need 58 times the amount of debris (0.95^58 is about 0.05). The ISS has to maneuver every now and then. Call it a 0.01% chance of having to maneuver in a half hour, and you would need a 30,000-fold increase of debris over present rates. On the long run, these debris particles would collide with each other. Some would deorbit, some would go to higher orbit, some would break down into flecks too small to harm a missile. Fortunately for your scheme, you can replenish the debris cloud by sending up rockets with enough velocity to make most their fragments reach orbit. If they get hit on the way up, well, that helps with the dispersal ... [Answer] No. Not gonna work. If I was facing this problem I see an immediate solution: I will deliberately launch my nukes into an orbit with an AP so low that it will decay in two hours. The nuke will deorbit itself into target. Kessler Syndrome can't reach that low because the deorbit time is two hours. If you managed to get it that low, then I will pick an "orbit" so low that it requires continuous thrust to avoid decaying in a quarter of an orbit. ]
[Question] [ In response to [Write once perpetual storage, is such a thing possible?](https://worldbuilding.stackexchange.com/questions/119648/write-once-perpetual-storage-is-such-a-thing-possible) Separatrix pointed me at [How could an ancient race warn the future in a universally understandable way?](https://worldbuilding.stackexchange.com/questions/105852/how-could-an-ancient-race-warn-the-future-in-a-universally-understandable-way) and [How might modern humans leave a message for 50,000 years?](https://worldbuilding.stackexchange.com/questions/3429/how-might-modern-humans-leave-a-message-for-50-000-years?noredirect=1&lq=1). While neither question addressed my concerns they have made me ask something else that will be useful much later, and possibly elsewhere too: Given modern materials what would be the best method for creating a long term record/warning of events, on the planet's surface, if we only had three days, or at most, a week to do it? I'm not asking what the message should contain or how it should be encoded, I want to know what medium it should be written on that will last as long as possible and can be fabricated in minimum time. The message will cover approximately 1200 A4 pages or 75m² of surface area, and will include both written and pictorial information. This is the absolute size of the representation that must be produced. Answers need not worry (nor consider) scaling it, or compressing it etc. Out of scope for the purposes of this question: anything about how such a message might, or might not, be translated in future, the message can be assumed to be translated as long as it is still legible. The message will be outside in an environment that gets only occasional light winter rainfall and is otherwise geological extremely stable and sheltered from erosion. The society leaving the warning has no expectation of survival and wishes to leave a warning that lasts as long as possible. They only have one shot at it and very limited time, which means they must use their currently existing technology. If we were leaving such a message on the surface of the planet, starting tomorrow, what material would we use? Important note: The message must be readable without auxiliary technological assistance, so they could, for example, use laser etching to write the message, but not an encoding that requires a laser reader. [Answer] ### You set three primary goals: * Achieveable in a few days * Sustaining the elements since it is supposed to be outside * Lasting as long as possible ## The key is a protective, transparent layer over your message Whatever material you use steel plates, ceramic tiles or etching in plain old stone, the fine details of the etching are significantly easier to use than the rest of the material. The details are what is more vulnerable, more exposed and also more crucial. Transparent durable plastic is suited for this as it is not biodegradable (yay, long-lasting pollution!) and - as it states - transparent. So you can cover your etched material entirely in it and have it still readable while not being as exposed to the elements. Even if the surface is partially damaged you can get a different angle and still see what's beneath. And even if it is mostly damaged you can still see there is something under there and remove the top layer and you can read it again. Getting etchings on steel plates and putting a thick layer of plastic on it is probably achievable within a single day. ## Placement is important While you can place the writings in the desert, not only do you risk them being buried within years, but also damaging the surface significantly and thus reducing readability. If you place them in an area relatively void of natural disasters and extreme climates (like most parts of europe) on the darker side of a mountain range (less UV light damaging the protective surface), it should last a while. You also need to make sure it is anchored well. So a slight earthquake does not make it all tumble downhill. Additional highlighters might be nice if you want to draw attention to it. Like big pillars or completely evened surrounding area, so it is easy to see from the air. [Answer] In such a short space of time your best medium is probably glazed and/or shaped ceramic tiles. While better can be achieved with more time ceramics can last an awful long time and are already produced on mass, if mass panic can be avoided then ceramic producing facilities could easily be re-purposed to create as many copies of the message as possible increasing the probability that one copy of the message survives. These copies should then be sent by plane to a wide variety of places preferably deserts, tundra etc... and buried in pyramid like structures which are then buried in earth. One copy should be put in geostationary orbit where it will last pretty much indefinitely (provided it doesn't collide with anything) though will require space travel to access. People will eventually dig at these oddly square mountains a little and (hopefully) find lots of pretty tiles. Even if these people have no interest in what the tiles say they will still dig them up for use in construction (assuming they are from a pre-industrial society that is) and likely the pretty patterned side is the one that they will show meaning your message will at least be seen. We have pottery from almost 30 thousand BC so this has a lot of longevity to it. Your biggest worry is making a universally understandable message. In truth though the best option is every option since we're all about to die in three days it really doesn't matter if we bankrupt the economy printing millions of sheets of laminated paper, creating massive earthworks in the shape of giant letters, sending people to the moon with buckets of red paint and hiring every artist in the world to paint it in a cave somewhere. If this is the plan people have decided on just go all out and hope that quantity brings the message to the next civilisation. [Answer] # How do you leave a message for future generations when all you have is 50 acres and a JCB? I think you can guess where this one is going, but Earthworks are one of the more remarkable and long lasting features of ancient civilisations. Whether barrows, dykes or ancient fortresses, banks and ditches are incredibly long lasting in their effect. Even when "destroyed" they leave their mark on the land for a long time, detectable thousands of years later with ground penetrating radar and showing up in the grass during droughts. While density of information isn't the strong point of this particular medium, shear size allows for considerable noticeability to future generations. [Answer] # Repeated Message in Multiple Languages on a Durable Material in a Geologically Protected Location Etched or carved metal and stone tend to survive throughout the ages. Technology for polishing and inscribing stone and metals such as aluminum at the industrial scale exist. As such, draft the message and have as many copies made as possible. Aside from hard stone engraving, there are corrosion resistant alloys already produced in abundance that could be employed. Some examples are: * High-molybdenum [alloys of titanium](http://www.totalmateria.com/Article24.htm) * Aluminum Alloy 5086 * Inox Steel Alloys (UNS S32205) ## Space Age Example Use a durable material NASA offered their take on this in the 1970's [Voyager's Golden Record](https://voyager.jpl.nasa.gov/golden-record/). Essentially, inscribe your message on an durable material, and include rudimentary pictogrpahic instructions for replay. ## Classic Age Example Write in multiple languages For less celestial timelines, the important trick seems to be to inscribe the message in multiple languages to improve the chances that it is interpretable by a future human civilization. The [Rosetta Stone](https://blog.britishmuseum.org/everything-you-ever-wanted-to-know-about-the-rosetta-stone/) is one of the most valuable archaeological finds because of this. ## Prehistoric Example Store in geologically protected location The paintings of [Chauvet Cave](http://archeologie.culture.fr/chauvet/en) are still interpretable by modern humans, but the message is probably less precise than you're looking for. Take away advice would be to put your message in a geologically protected place. [Answer] You can have people 3D print the message on their personal and business printers. Most plastics never biodegrade, except in very specific conditions, so they should last for 50,000 year. As other answers suggest, having multiple copies will make survival of the message more likely. > > <https://science.howstuffworks.com/science-vs-myth/everyday-myths/how-long-does-it-take-for-plastics-to-biodegrade.htm> > > > Granite, slate, ceramics, concrete, and other hard natural materials can be milled or laser engraved/cut with the message as well. Many maker/hacker-spaces have CNC mills and/or laser cutters capable of doing this, as well as private businesses. It would only take a trip to the local home improvement store to get a stack of pre-made 10-12" square tiles to get this project crowd sourced, same as the 3D printing. You can also mill and/or laser cut sheet plastics. Acrylic is cheap, flexible, stronger than glass, and readily available. Polycarbonate isn't as laser friendly, but will still etch and is tougher than acrylic. Both can be sourced as 4 ft x 8 ft sheets. Crowd sourcing is probably the best way to get a large message like this together in a short time, and it gets around the so called "one shot" you think you have time to make. Giving small sections to a variety of people with specific instructions on how to make the end product will give you the quickest results. To hedge your bet, you can give one group instructions to do a set in laser etched polycarb, another group CNC mill engraves it into granite headstones, another group is told to 3D print it, etc. Once the individual pieces are finished, they are co-located and assembled into the finished product, with each groups efforts being distributed. What I mean by that is maybe the headstone groups is in Los Angeles, the 3D printer group in New York, and the polycarb group in Denver. You can even have this duplicated in each continent, to hedge your bets even further. So, for example, the 3D printing is also done in Melbourne, Paris, Moscow, London, Capetown, and Rio de Janeiro. Each continent or location can have their own translation, so it becomes a Rosetta Stone, in case one or more language is more easily decipherable by it's finders than another language. Some of these translations can include pure math, binary, pictorial, as well as current spoken languages. Also, remember to number the pages, somehow, so your message isn't garbled when the cargo container is ripped apart and spread across 3 square miles of ocean floor. Or whatever. With potential dozens of these messages around, someone is likely to eventually find it. Someone will do some spelunking in caves that used to be Buddhist temples, find perfectly straight holes in the ground with radioactive rust piles at the bottom (missile silos), and other locations were the message copies are stashed. A reasonably smart (or lucky) being will decide that all the sheets of plastic (and piles of oddly shaped rock) that have etchings on them mean something, will want to get them into one place, and may even start to figure out that there's a real message in all that (presumably) purposeful surface scratching and/or raised ridges. Edit: Units are there for a rough comparison of size. I doubt that a country that uses SI units is going to have products that measure exactly 4 ft x 8 ft panels, as that comes to oddly specific (and fractional) 1.2192 m x 2.4384 m. I would hope they round to something "normal"/"useful"/easy-to-measure like 1.5 m x 2.5 m. Or maybe they use 2 m x 2 m panels. I haven't lived in these countries, so I don't know what size building materials actually come in. So, I don't see how converting from UCS to SI units really adds anything meaningful to this answer. Edit 2: Polycarb is more scratch resistant than acrylic, and can have a scratch resistant coating added, like they do for glasses lenses. > > <https://www.vsp.com/polycarbonate-lenses.html> > > > Also, I don't see how people would use table tennis balls for this message, since nitrocellulose is the "spontaneously combust"able plastic Mark is talking about in his comment. > > <https://en.wikipedia.org/wiki/Nitrocellulose#Film> > > > Acrylic is more temperature sensitive than polycarb, and acrylic can be used without warping up to some pretty extreme temps for the surface of the Earth. "It can be used continuously in a temperature range of 170-190°F. It begins to soften between 210-220°F and starts to melt between 300-315°F..." > > <https://www.plasticsintl.com/datasheets/Acrylic_(PMMA)_Extruded.pdf> > > > Just because it's called "organic" doesn't mean it's found in nature. Organic solvents are man-made and have a low boiling point, so even if they were naturally occurring, they would boil away too quickly to do any real damage in even room temperatures. > > <https://www.corrosionpedia.com/definition/2263/organic-solvent> > > > UV light can damage some plastics, but it can also be hardened against the effects. > > "Many of us benefit from UV radiation-cured protective polymeric coatings, such as polyurethane-acrylates, on exterior automobile components." > > > <https://www.coleparmer.com/tech-article/uv-properties-of-plastics> > > > Some plastics aren't as susceptible to that damage as, say, polypropylene. > > "Unmodified types of plastics that are regarded as having unacceptable resistance to UV are POM (Acetal), PC, ABS and PA6/6. Other plastics such as PET, PP, HDPE, PA12, PA11, PA6, PES, PPO, PBT and PPO are regarded as fair. Note that a PC/ABS alloy is also graded as fair. Good resistance to ultraviolet rays can be achieved from polymers extruded by Zeus such as PTFE, PVDF, FEP, and PEEKTM. The only plastics found with excellent resistance are the imides, Polyimide (PI) as used in the Hubble Space Telescope and Polyetherimide (PEI)." > > > <https://www.coleparmer.com/tech-article/uv-properties-of-plastics> > > > [Answer] ## This is already sort of being done There's an effort to preserve knowledge for the ages at the moment, inspired by Sumerian tablets: <http://www.bbc.com/future/story/20161018-the-worlds-knowledge-is-being-buried-in-a-salt-mine> <https://www.memory-of-mankind.com/> > > The Memory of Mankind team hopes to create an indelible record of our way of life by imprinting official documents, details about our culture, scientific papers, biographies, popular novels, news stories and even images onto square ceramic plates measuring eight inches (20cm) across. > > > These are hardened, Alkalai, acid and extreme temperature resistant ceramics, engraved with up to 5M characters, or 50K characters with pictures. they are then stored deep in a salt mine in Austria (the salt helps prevent moisture). They also produce small simple map tokens identifying the location in Europe, if these are lost then some larger, cruder installation above ground could be enough of a pointer for your future seekers of knowledge to be aware there's something there, then delve in to find the detail. [Answer] Engrave your message in large-ish (big enough to be seen/found) gold plates, perhaps 1/4" thick and engraved/carved to a depth of 1/8" - nice and deep, keep the image around from wear, etc. over the years. Don't use 24k of course, 14k would do. Multiple copies in multiple locations. Mark locations with big huge solid construction of something, just to attract attention to it. Shiny. Durable. No corrosion, etc. to worry about. Edit to follow up on several comments 1/4" is 6.35cm 1/8" is half that... If you feel that gold - even a 50%-ish alloy - is too soft and bendy, a harder metal could be used, and a thick gold plate covering it to protect it from the ravages of time and chemistry. Additionally, having multiple copies in multiple locations would help ensure that one or more of the copies would be viable when found. To protect against looting, simply make the core large enough and heavy enough that anyone with the technology to move it, etc. would be able to notice the warning and perhaps investigate that before recycling it. ]
[Question] [ In my most recent question, I asked for a material other than calcium and collagen that could form skeletons in alien creatures. My favourite answer was bio-steel; "Iron with a small percentage of elemental carbon". There will be scavengers on my world; scavengers as powerful to the alien carcasses as spotted hyenas are to Terran ones. And that means that their jaws need to be able to crush the steel bones. So, what anatomical adaptations would be best for a scavenger that's built to crush iron bones? Assume a radius of about 5 cm and a density of 7.5 g/cm^3 [Answer] [Acid](https://www.youtube.com/embed/49MnzqB28qQ?start=47&end=53) Your scavenger needs to way to digest the chunks of bone it swallows. So it already needs some sort of strong acid already in its biology. A more potent form of the same acid is injected into the bones to soften them before they are broken up and swallowed. Note bones are highly porous on the inside which means the acid has more surface area to work with. [![enter image description here](https://i.stack.imgur.com/iW4cJ.jpg)](https://i.stack.imgur.com/iW4cJ.jpg) These aliens might have a very strange metabolism where the acid is very common and does not react strongly with their flesh et cetera. The same way water is a very common in Earth biology but has a violent reaction with certain metals such as caesium. [Answer] Steel bones won't break like terrestrial bones do so you need to look at metal working tools first and then work back to real biological designs with similar qualities. To make an appreciable impact on what is essentially sheet metal tubing you need one of two things, either a [punch](https://en.wikipedia.org/wiki/Punch_(tool)) or a [shear](https://en.wikipedia.org/wiki/Shearing_(manufacturing)) of some kind. If it's a punch it's designed to push through the steel in many places allowing the marrow to be sucked out the multiple holes. A shear on the other hand would be used to cut the ends off the bones to give access. In nature a punch style tooth would be something like those of the [crocodile](https://en.wikipedia.org/wiki/Crocodile) or the [anglerfish](https://en.wikipedia.org/wiki/Anglerfish), long conical teeth designed primarily for penetration. The beak design of [parrots](https://en.wikipedia.org/wiki/Parrot#Morphology) is a good example of a shear, the two halves of the beak are offset and come together from the back forward cutting most objects open, the hook prevents objects from being pushed out of the birds mouth in the process. You might also look at the approach the [Bearded Vulture](https://en.wikipedia.org/wiki/Bearded_vulture) takes to bones. They simply swallow then whole and their super acidic stomach juices dissolve everything. They do have to be somewhat selective about size though. [Answer] ## Scavenging Carcaseaters > > Crushing iron bones might be prohibitively expensive in terms of animal's metabolic needs. > > > The meat and fat have the most calories for most animals so they will want to go after those instead of the bones. [![Ant eater](https://i.stack.imgur.com/3Fv5i.jpg)](https://i.stack.imgur.com/3Fv5i.jpg) Instead I propose something like and Anteater, with a long but thin tongue that can scoop in between bones in order to eat the dead animal starting with the softer innards. The tongue will want enzymes that break down muscle tissue to more easily consume the meat, something like the pineapple enzyme [Bromelain](https://en.wikipedia.org/wiki/Bromelain) would probably work in the saliva. ## Bone Snakes With the carcass clean there can be a large symbiotic snake like creature which would consume these bones and slowly digest them for a long term energy source. They would need to be large enough to hold entire bones in their stomachs, so I would make them long enough to hold an entire femur and still move. [![fed snake](https://i.stack.imgur.com/9JUsB.jpg)](https://i.stack.imgur.com/9JUsB.jpg) This way you have 2 species which benefit from a single death and neither have to complete the costly action of actually going through the bio-steel bones. [Answer] Found rocks. To crush iron, you need something harder that the iron and leverage to apply it. <https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness> Iron is not that hard; 4 on the Mohs scale. That is probably good for application as a bone as you want the bone to flex a little, not shatter. But it is easy to find environmental materials harder than Mohs 4. Quartz, granite and basalt are all common surface rocks and have mohs hardnesses of 6-8. Your creature would have double hinged jaws like a bolt cutters, to maximize leverage. [![bolt cutters](https://i.stack.imgur.com/vtn2H.png)](https://i.stack.imgur.com/vtn2H.png) The crushing surface would be comprised of rocks found in the enivronment and the creature would always be on the lookout for these, or perhaps have areas where it would return to where good tooth rocks could be found (it would learn these areas from its mother). Good rocks would have a flat side and a sharp side and would be rotated in the mouth such that the flat side was against the jaw bony plate and the sharp side would be inward, applied to the iron bone. There would be more rocks than needed in the jaw, to make sure there were always some ready for bone crushing. Blunted or broken tooth rocks will be spit out. The use of found rocks for digestion is very much done by birds and crocodilians as well as extinct reptile lineages. Birds carry ingested grit and pebbles in the gizzard to grind hard food. Crocodilians do the same with rocks in the stomach. Using rocks for tooth-type jobs is not a stretch at all. [Answer] This would be a tad long for the comment section, so forgive me and allow me this suggestion: Since you're proposing a scavenger, have a species that moves in packs. From their mouths, they expel a protuberance that releases an enzyme that will allow them and only them to eat the 'melted' meat without other predators to disturb them. Once they leave alone the carcass, the sentients can pick up the cleaned iron bones and make use of them EDIT: HOLD IT RIGHT THERE! FOUND IT! Dragons! Your 'scavengers' are bonafide dragons. Oh, sure, they are natural predators and mighty ones as well, but...what if the females decided to partake in scavenging so that they melt the iron inside their stomach and use it to coat their eggs with an extra-hard casing? The Hatchlings would be born with the help of mum who'd break the egg with her jaws. And this would also explain the folklore with dragons and their hoard -people mistook highly protected metal eggs for riches! This would solve the jaw strength without recurring to exotic design. And those iron bones would turn out to be useful! [Answer] You really just need teeth that can withstand the damage caused by crushing the steel, currently bones are incredibly hard to break. If you've seen swords or axes attacking beef thigh bones, you'll know that steel ones might be easier to break! (actually, I recall some Forged in Fire episodes where hardened steel knives [are tested against bones](https://www.youtube.com/watch?v=PB-IdRkquxs), and the knives don't exactly come off unscathed. I imagine un-hardened steel would be next to ineffective) So scavengers with bone-crushing jaws like we already have in the real world, maybe with metal teeth themselves - if you have steel bones, why not steel teeth too. [Answer] > > Crushing iron bones might be prohibitively expensive in terms of > animal's metabolic needs. > > > Alexander has a valid point. Creatures don't evolve to be cool, they evolve to be effective. Wasting energy on crushing ridiculously strong bones when the rest of the animal's flesh is still (presumably) soft or relatively soft is a bad adaption. You did not tag your question with reality-check or science-based, so I don't know how interested you are in more practical solutions to this problem. But here are some other options. If you want the predator to be effective at disabling movement: Hamstring the enemy instead. Bones need muscles and tendons to move, so if you slice them the appendage won't move at all. This kind of mimics breaking bones in terms of the immobility. For this, the predator just needs razor sharp teeth with a long angled edge for biting and slicing. There are a lot of opportunities here for wonky and scary looking alien predators that retain function. For example long blade like chins, teeth, etc. If you want the predator to be effective: Make your predators bite and run predators. There is a precedent for this in terms of Cookie Cutter Sharks. > > Cookiecutter Sharks, bite off bits of whale blubber rather than > attempt to kill the whale - which works out much better as the sharks > are significantly smaller than the whales. > <https://en.wikipedia.org/wiki/Cookiecutter_shark>, > Thanks @Morgen for this information. > > > Instead of outright killing prey your animals can just run up to their targets, take one big meaty bite out of them and then run away with a mouthful. This seems very practical in a scenario where prey has iron bones. A further look into breaking bones: Breaking iron bones poses a lot of other challenges too. Drawbacks that effect the predator immediately after it succeeds. Remember that carbonized iron is very brittle and very strong, so: 1. Breaking carbonized iron requires a lot of force but when it does break it will splinter and its shards will fly everywhere like a small shrapnel grenade. So a big problem here is that if the predator's mouth is not also heavily reinforced, cracking a bone might mean instant death as shard of very sharp carbonized iron fly straight into its head/throat/etc from inside its mouth. 2. After cracking the carbonized iron, at least some of the very sharp shards are going to be swallowed and have to pass through the predator's body. The inside of an animal is generally not very tough, so this is another good way to die; via massive internal trauma/bleeding. So an extremely reinforced digestive system will also be required, or else very powerful digestive acid to break the iron down in the stomach. In the end the adaption would require a lot of other complimentary adaptions as well. [Answer] Something like a [mantis shrimp](https://en.wikipedia.org/wiki/Mantis_shrimp), which, even at it's small size, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 m/s (83 km/h; 51 mph) from a standing start, has smashers that could break many things. (see also [The Oatmeal](http://theoatmeal.com/comics/mantis_shrimp) for more fun information) ]
[Question] [ In my book, Oumuamua was actually a large alien invasion/colony vessel. So, suppose we have an invading ~100 km long alien colony ship flying towards Earth. Suppose also that the aliens are unable to fully cloak themselves, but have a way of altering/reducing their visual or infrared signature. Is there any reasonable way they could trick Earth telescopes (like Spitzer) into believing they are registering a much smaller, Oumuamua-like asteroid? The aliens probably shouldn't worry about fully mimicking the exterior of the asteroid, as Earth telescopes would only see a pale dot. The aliens are carbon-based and 3-dimensional. They are not familiar with space-time warp (the ship was travelling at subliminal speed) and do not posess other hyper-advanced tech. So, they can for example have beam weapons, but are unable to phase out from reality or perform any other hard to understand tricks which we know nothing about. Their technology needs to be at least somewhat understandable. How would they go about that? [Answer] The ship is very long. [![o gif](https://i.stack.imgur.com/hCyJR.gif)](https://i.stack.imgur.com/hCyJR.gif) <https://en.wikipedia.org/wiki/%CA%BBOumuamua> Here is a simulation of Oumuamua tumbling. It is thought to be an elongated tumbling structure because the brightness of the single pixel that it appears as varies a lot as regards albedo. One way to explain that for a rock would be a shape that presented a much varying surface area - a cigar shape or a disc. Your km long ship is very long and thin - a spear pointed at Earth. From the vantage point of earth it too is a single pixel. It does not tumble. On the prow of the ship they have a device which changes albedo and so presents the change perceived for Oumuamua. Maybe they were trying to fake us out. Or maybe the prow of the ship is a dancing mermaid and that is just how it looks from Earth. From the vantagepoint of Jupiter this object might look very different. [Answer] If they are only worried about observations from a single direction (Earth), 'cloaking' is simple. Have the earth-facing side be covered by a large mirror that reflects incident sunlight, both visible and infrared, away from Earth's direction. From Earth there then wouldn't be anything to see. Maybe make sure you don't accidentally reflect light from a bright star towards Earth, but I think reflected starlight would be much too weak to be observable with our current telescopes. My guess is that for practical purposes this alone would be enough, as the majority of large telescopes detect reflected sunlight, i.e. visible and shorter infrared wavelengths. There are only a [handful of large telescopes that can detect thermal infrared](https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes) (only 3 on that list can observe thermal IR (around 10 µm) and are still operational), so the chances of one of those spotting the ship is minimal. If you also want to hide your thermal infrared signature you need to cool the mirror to very low temperatures. That requires a big radiator on the other side of your ship to reject the heat, but if you are only worried about observations from one direction that is not a problem. And now your big ship is basically invisible to Earth, though not from other observation directions. The way to defeat this 'cloak' would be to have observation posts far away from earth, so the solar system could be observed from multiple vantage points. But we don't have that now. If you want to make it look like an asteroid, maybe the 'cloak' is not quite good enough to be entirely invisible, or doing so would be too expensive, so the aliens opt to emit a little bit of radiation towards earth (on top of the radiation that leaks through the 'cloak') to simulate an asteroid. Related: [Stealth in Space: How realistic is it?](https://worldbuilding.stackexchange.com/questions/23313/stealth-in-space-how-realistic-is-it) (Note that defeating stealth depends on having lots of observation platforms scattered through space) [Answer] Keep in line with the sun Earth is the only inhabited spot in the Solar system. There is a telescope on moon/earths L2 now, but its deep infrared range does not allow it to look into the sun, or next to the sun. An incoming alien ship could approach the solar system in such a way, that it resides behind the sun, as viewed from Earth's orbit. During the actual invasion, the ship will proceed course: there's a turn (sling) around the sun now, which is a risky 1-3 days operation, where the ship will be visible. Proceeding after that, it could approach the planet while the sun's daylight disturbs our observation. [Answer] become the asteroid. Theoretically a cheap and easy way to achieve this is to simply coat your invasion vessel with a coating of space rock and specialized materials capable of fooling infrared sensors. This will both fool telescopes and protect your alien invasion vessel from exterior hazards such as asteroids that may pose a threat to the ships interior. But, to be more realistic it doesn’t seem necessary to do anything. When humans find out the invasion ship has heat signatures, they wouldn’t be able to figure out exactly what’s causing them and how to prevent the invasion until it’s too late. [Answer] ## Dark matter Most of the alien ship, and indeed the aliens themselves, is composed of dark matter. It cannot be observed directly, and it's not nearly massive enough for us to detect its gravity. The baryonic component, which we know as Oumuamua, is regular matter they brought along as source material from which to manufacture the weapons and other tools they'll use against us once they arrive. This matter has been specially prepared so their dark matter bodies and technology can interact with it. ]
[Question] [ So I’m sitting here populating my alien world with critters to run around, eat each other and do critter stuff (as is the custom). At some point a thought came over me that their organs should be weird crazy shapes to mix things up a little. ## What are spiral lungs good for? The organs are sort of shaped like conches that sit comfortably inside the rib cage. Like a very long lung that’s coiled up like a python, except it’s one structure and can’t be straightened out. The trachea connects to both ends of the lungs for optimal airflow (because birds are unmatched in the breathing department). Aside from confusing the air molecules inside I’m not entirely certain what the advantage would be. My hypothesis is that air stays in the lungs longer this way in order to maximize gas exchange. Tips for answerers: The method of respiration can be by compression or with air sacs circulating air through stiff lungs. Both versions should be explored in the answers to give a good idea of where they stand. [Answer] ## Countercurrent heat exchange Not quite sure the exact kind of spiral you mean but if an organism needs to maintain a very different body temperature from the gas around it in an extreme environment and is otherwise well insulated then having incoming and outgoing gas spiral around each other through counterflowing passages might allow a stable temperature to be maintained. For example penguins feet use something similar for blood to reduce heat loss through their feet in extremely cold environments. Blood going one direction exchanges heat with blood going the other in a spiral. You might try something similar with gases being breathed in and out. [![Penguins feet](https://i.stack.imgur.com/rYL5T.png)](https://i.stack.imgur.com/rYL5T.png) [Answer] A one-way air passage When we (humans) inhale and exhale, the air enters the lungs and exits them through the same passage. So minimizing the distance to the trachea from any part of the lung is an energy-saving optimization in our lungs. But if your organism has two different entries into the lung, this allows us to use valves to have a directed, one-way flow of air through the lung (even if both those entries connect to the same outside opening). Then their lung might be more similar to a human gut - a long tube, with complications along the inside to increase surface area. But our gut is way too long to fit in our body, so it's all coiled up - a similar adaptation with your one-way lung would seem likely. Circulation via compression: If we want to contain the tube nicely inside an expanding/contracting muscle membrane, a spiral could be a convenient shape to pack it. Circulation via "air sacs in stiff lungs": Not really much different--it's still advantageous to pack the lung tissue together; and the air sac(s) can simply be placed at one end or both. An advantage of one-way airflow: countercurrent exchange [Countercurrent exchange](https://en.wikipedia.org/wiki/Countercurrent_exchange) is a well-known feature ([already used in the lungs of birds](https://en.wikipedia.org/wiki/Gas_exchange#Birds), which you mentioned, and in fish's gills--with thanks to @Turksarama for pointing that out to me) that optimizes the transfer of gas (or heat, or chemicals dissolved in a liquid) across a membrane. For your one-way lung, this would mean you direct the flow of blood the around the lung in the opposite direction to the airflow. [Answer] What Qami said about [one way passages](https://worldbuilding.stackexchange.com/a/215336/21222), plus what Nyakouai said about [increased gas exchange surface](https://worldbuilding.stackexchange.com/users/20021/nyakouai), but let me add one more thing: voice organs. Your aliens might not have vocal cords like we do. Instead they vibrate different sections of the conch in order to speak. The larger the piece the deeper the voice. So an alien's vocal range depends on the sizes of their conch lungs, from the biggest cavity providing the lowest frequency to the smallest cavity giving the highest pitch. This is very similar to how we humans perceive sound, by the way. We have an organ inside our ear called the [Cochlea](https://en.wikipedia.org/wiki/Cochlea#Hearing) which is also a spiral (the emphasis below is mine): > > The hair cells in the Organ of Corti are tuned to certain sound frequencies by way of their location in the cochlea, due to the degree of stiffness in the basilar membrane. This stiffness is due to, among other things, the thickness and width of the basilar membrane, which along the length of the cochlea is stiffest nearest its beginning at the oval window, where the stapes introduces the vibrations coming from the eardrum. Since its stiffness is high there, it allows only high-frequency vibrations to move the basilar membrane, and thus the hair cells. The farther a wave travels towards the cochlea's apex (the helicotrema), the less stiff the basilar membrane is; thus lower frequencies travel down the tube, and the less-stiff membrane is moved most easily by them where the reduced stiffness allows: that is, as the basilar membrane gets less and less stiff, waves slow down and it responds better to lower frequencies. In addition, in mammals, the cochlea is coiled, which has been shown to enhance low-frequency vibrations as they travel through the fluid-filled coil. This spatial arrangement of sound reception is referred to as tonotopy. > > > [Answer] Extraction First off, it is a nice idea, but not practical. The air is more difficult to push through the long winded pipes, costing more energy. That out of the way, you can have super extraction. Lung lining is designed much like the intestines. It's made so there's a lot of surface area. The difference is that lungs are made to easily replace their gas with fresh oxigen holding particles that can swirl around a bit. Your organisms have much more surface area for the lungs. That means more efficient oxygen extraction. This can change on what is needed. Either more quickly extraction, preventing the organism of using bad anaerobic processes in extended effort situations, or used to hold their breath longer. This last one won't be too much longer mind you. [Answer] What an alien idea. I like it. I suppose your weird shape could somehow increase the total contact surface of your lungs, making them more efficient compared to boring old regular shaped lungs. There could also be more major blood vessels running in the coils of it, allowing for a quicker transfer of oxygen into vascular system.1 Or (weird idea), it developped this way because your creature is somehow exposed on a regular basis to void. To avoid air being pulled out of the lungs, your coils are lined with sphincters that contracts and isolate sections of your lungs to create pockets of air. 1: Keep in mind, those are ideas from someone that hasn't had a biology class in the past 10 years. [Answer] ### An internal cooling coil. Building on Qami's idea of a one-way airway, a coil-shaped "lung" could also serve the purpose of cooling the body from the inside, in the same way a cooling coil would, by running a colder fluid through and around a warmer body or tube. That might come in handy e.g. for large animals with active metabolisms that generate a lot of heat and have a low (skin) surface area to volume ratio. If a biological process like digestion or other metabolic functions produces a really strong exogenic thermal reaction, maybe the lung could loop around that area to cool it off. Having a one-way system with an 'in' and an 'out' would allow you to cool off continuously with no need to inhale. [Answer] ## Reality Check = FAIL! The first important consideration for this kind of breathing system, the conchoid lung, I believe, will be [dead space](https://derangedphysiology.com/main/cicm-primary-exam/required-reading/respiratory-system/Chapter%20076/physiological-consequences-increased-dead-space). The other important consideration is that your system isn't set up and doesn't function like a [bird's respiratory system](http://people.eku.edu/ritchisong/birdrespiration.html). So, what will happen? --- Dead space is the term for air that sits in a tube that can not be properly inhaled or exhaled. In other words, your chest cavity is only able to expand so much, so the amount of air inhaled is limited by the available chest volume. The more tubing you add to the system, the harder it will be to bring fresh air in and clear stale air. The air that gets into the very end of the lung will become stale and will be unlikely to clear. In a human lung, the entire volume is taken up by increasingly smaller branches and then even tinier ones. So, the large trachea divides into two primary bronchi each of which divides further into a couple more levels of smaller secondary & tertiary bronchi. These in turn divide into many bronchioles which terminate in alveolar sacs where gas exchange happens. This works well because the distance from any one alveolus to the outside is relatively short and the respiratory cycle can fill and empty the lungs without (much) air remaining inside (there will always be some). Your conchoidal lung basically presents us with a very long tube. The distance from the most proximal alveoli to the outside will be comparable to the distance of the alveoli in the upper lobes of the human lungs. However, the distance from the most distal alveoli to the outside might be a metre or more! That part of the lungs will be filled with dead air that will hardly ever be cleared. You'll have to either scrap the conchoid lung or else scrap the relatively humanoid thoracic cavity you described. See below under reinventing the wheel. Bird breathing is complex! --- Birds have two lungs, nine air sacs, and a four stroke respiratory cycle. Inspiration brings 1. the current breath's fresh air from outside into the posterior sacs and also 3. the previous breath's stale air from the lungs into the anterior air sacs. Exhalation pushes 2. the current breath's fresh air from the posterior sacs and into the lungs and also 4. pushes stale air from the previous breath back to the outside. The result is a continuous flow of air through the lungs. The extra tubing coming off the distal ends of the conchoid lungs will not effect continuous breathing. In stead, they will just create more dead space. Conclusion. --- As it stands, I think your system will both fail to produce a superior volume of air flow & gas exchange and also will defeat itself by taking up too much valuable space within the chest with extra tissue and dead space. Lastly, if you just connect those extra tubes to air sacs, well, then all you've really done is reinvent the wheel that avian dinosaurs invented millions of years ago. The argument for increased surface area for gas exchange fails again. Whereas before, only the most proximal portions of the lungs would really receive fresh air; now, only the most distal parts of the lungs will receive fresh air. Much of the lung's coiled up length will just have stale air passing through it. I think diminished returns on investment will eventually lead to smaller, more straight forward lungs. [Answer] A spiral-shaped lung could be good for separating out different-sized particles from the air that your creature inhales. The shallower curve at the outside of the spiral will allow smaller particles to flow around it, but the centrifugal force will push larger particles into the lining; and so on, as the curve gets sharper towards the centre of the spiral. If your creatures live on a planet with lots of different kinds of dust, spores, and other particles which the creatures are adapted to inhale but which need to be filtered (e.g. maybe they eat the spores from the air but need to cough out the dust), then a spiral-shaped lung could function as a filter. [Answer] Two crazy ideas 1. For symbiosis: posit another creature which normally lives in spiral shapes (like a conch/shell) but sometimes found its way into the lungs where it supplied a symbiotic function like producing oxygen and helping the critter stay underwater longer, or filtering blood and converting waste product into useful product or less toxic waste product. Over time, critters develop spiral shapes in order to better acquire and accommodate the natural shape of their symbiotes, and over time critters have gotten used to having stuff live in their lungs. 2. For reproduction: if the lung cavity doubles as a reproductive cavity, then perhaps it has undergone an effect similar to the Earth-borne [duck](https://en.wikipedia.org/wiki/Duck#Morphology). [Answer] You said "air" but didn't really specify the composition of the atmosphere. If it was some sort of electrically-charged fluid, running it through spiral lungs would be useful for inducting electrical current. This could be a sort of "electrical respiration" for this species, rather than chemical respiration like we have. This could also have the nice side effect of, when they go for a run or a bike ride, they could keep whatever they have that's analogous to cell phones in their pockets. Then by the time the exercise was over, they devices would be fully charged. [Answer] ## Gas chromatography The air of your planet is far more complex than the atmosphere of Earth. A rich mix of hydrocarbons, silanes, germanes, amines and fluorinated compounds, it provides many useful chemical precursors. Unfortunately, your species' membranes, like ours, are lipid bilayers with little capacity to control which compounds cross, whether beneficial or baneful. With the spiral lung, your organism breathes in a brief pulse of external air, followed by a carrier gas recycled internally from the absorbed inert compounds. This adheres differentially to the polysaccharide- and water-coated solid support phase of the spiral lung. After a moment, inhalation stops. This leaves each type of chemical having travelled a different distance depending on its hydrophilicity, and cells specialized to deal with each type of chemical constituent do so - whether to absorb, detoxify, or route through toward small channels for rapid "exhalation" from small ducted glands. The system is not tremendously efficient as a means of respiration - I'm going to assume the primary means of absorbing oxidizing agents is by drinking compounds that rain down in the wind from the sunlit side of the planet, and that supplemental hydrocarbon intake is done by ordinary eating. But the breathing apparatus could deliver a wide range of useful trace elements from an otherwise hostile atmosphere. ]
[Question] [ Humans are the equivalent of bacteria to planet-eating monsters. And since, as we all know, eating humans is dangerous business, these monsters have decided to cook our great planet Earth before eating it. Handwaving the monsters and all that comes with them, what is the minimum temperature they have to heat up the Earth to before eating it in order to eliminate humans and prevent possible infections? Luckily for us, their ovens are slow and the Earth heats up slowly (around 30 °F/17 °C per year), which, I assume, would give us enough time to react to the change in temperature and allow us to start building infrastructure to prevent our inevitable death. Though, of course, once we're in the oven there's no leaving it. Everything except for the monsters and the fact the Earth is heating up at an alarming rate is the same as it is today. I'm assuming there is no way to survive past the boiling point, though maybe there are ways to handle it if we keep water at higher pressure, but I also think we'd be able to withstand more than 160 °F/70 °C which would normally be deadly pretty quickly to a single human. [Answer] The humans are toast (well, medium rare anyway). Short version : ten degrees Celsius should do it, twenty would be more than enough. > > Luckily for us, their ovens are really slow and the Earth heats up really slowly (a few degrees celcius every year) Which, I assume would give use enough time to react to the change in temperature and allow us to start building infrastructure to prevent our inevitable death. Though, of course, once we're in the oven there's no leaving it. > > > Have a quick look at the news. Scientists have been patiently (and impatiently) explaining to everyone that we're screwing up the planet's weather and, hey, we call it global warming and it's going to be bad. And in the many years since they started doing this precisely how much action has been taken by the powers that be to do anything constructive about this : nothing. So the assumption humanity as a whole, which has never acted entirely together on a single project and is the universe's prime example of "cut off your nose to spite your face", will act in a mere five years to do something is the wildest optimism. That said ... > > Everything except for the monsters and the fact the Earth is heating up at an alarming rate, is the same as it is today. > > > Exactly the same as it is, because we're already heating up the atmosphere at an alarming rate ourselves. :-( Well we don't function for extended periods at high temperatures and high humidity. The [Mayo Clinic has a page on Heat Exhaustion](https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250) and it's worth reading. In short at normal humidity levels you can just about cope with $37^\circ C$, but as humidity rises you'll start really over-heating at "only" $33^\circ C$. Well in your scenario humidity will rise almost everywhere (hard to be precise), and that means much hotter feeling and much more difficulty doing basic tasks. As your temperature rise is about a few degrees every year, it's only gong to take a year to make some places barely livable and a mere three years to make even places like Ireland become a sweltering tropical hell. But that's OK as the ice cap will rapidly disintegrate in those temperature rises and the massive worldwide flooding, torrential rainfall and resulting landslides and other issues will render most of the inhabitable areas real disaster zones. On this time scale ( a few years, not even five ) they won't even have set up committees to argue about whose fault it is nothing is being done, let alone solve the problem. In practical terms there is no way the world's industrial and food production systems will survive with such enormous damage and I'd expect worldwide famine and a reduction in industrial and economic output that would be catastrophic and make it virtually impossible to develop a response to the crisis (even if it was politically possible). Note that all life on the planet will be affected, from ocean plankton to penguins. Nothing currently living on Earth (with a few oddball exceptions) is capable of adapting that quickly to both a huge climate change (that's increases in pace) and the sudden destruction of the ecosystems they depend on. We depend on all that other life to keep us going, so our survival alone is not an option. If the aliens keep pouring on the heat and increasing temperature at that rate, it's impossible for a sustained survival of more than some thousands of humans in e.g. a specially built emergency bunkers. But even these can't survive indefinitely. After ten years or so (imagine trying to store and grow food in such a system) the food will start to run out, and the power systems will fail as will heat regulation (because the outside keep getting hotter). There won't be infrastructure to supply parts to replace failing equipment. Things will rapidly go downhill as that happens and in say twenty years even these shelters would be lifeless. By twenty years or so, while the temperature is notionally going to increase by some $60^\circ C$ (which is essentially instant death), the atmosphere will most likely have tipped into runaway greenhouse effect and we'll be heading towards (if not actually in) an atmosphere more like Venus than anything you'd find on Earth now. Once again, WB SE has killed the glorified monkeys. Yay. :-) [Answer] Unshielded humans will expire above 40 C Well-prepared humans should be able to hang on to 1000 C and more for some time. Due to our temperature management, humans can withstand temperatures above 100C for hours, and between 40 and 50C for days. However, all natural temperature management depends on evaporation and works only in low humidity. In high humidity, human won't be able to cool below the ambient level, so body temperature just above 40C would be fatal. If entire Earth is in the oven, it would become an equivalent of runaway greenhouse effect, and all surface would become uniformly hot and humid. But if we can build a cooling enclosure with independent power source, humans can hold on at much higher temperatures. The key here is to provide effective thermal insulation and cooling. We currently don't have refrigeration units capable of working at very high temperatures, but below 1000C the challenge would be engineering one, not scientific. Above 1000C the difficulties would multiply and it is difficult to tell whether durable shelter can be constructed. And I guess at 2000 C the answer is "no" - we can not build it with today's tech level. [Answer] Depends a lot on how humans prepare. Without humanity adapting, with the above scenario you'll probably collapse society in 5 years and make us extinct in 10. However, just heating up won't hurt well-prepared humans. For example, dig a few hundred meters into a mountain, and you won't even notice the external heating. Easiest method for humanity to create Noah's Arc 2.0 in order to survive this: Grab a nuclear submarine. Board with a group of genetically diverse people. Store all the food you can. For long term survival, also store genetic material of lots of other people, so you can clone those genes back into the population later on, otherwise humanity will die of incest-related problems after a couple of generations. This sub can last as long as it's food stores do. Most of the ocean is at exactly 4 Degrees Celcius. The only ocean water that isn't is really close to the surface. So that will take care of any heating. The oceans will not heat throughout. The top layer will heat, but will be boiling before long, while the sub can just go a tiny bit deeper. As you boil more ocean, the sub can just keep going deeper. [Answer] Cell death occurs at 65 degrees Celcius or 149 F. I am informed that is pretty much universal for cellular organisms on our planet, or at least not those living on undersea vents or boiling mud. As noted in a previous answer, human beings are adept at creating temperature controlled enclosures and depending on available power some could survive indefinitely. This temperature will also kill the plants and bacteria on the planet -- assuming they had a way to raise the temperature equally given we have large bodies of water that will constrain local temperatures to 100 degrees Celcius until they boil away. It seems odd that humans are lethal pathogens to planet eaters, and not goats, cattle, leaves. Unless it is our intelligence and tenacious drive to survive that makes us dangerous. SO, maybe consider alien phages that swarm the planet-devouring those pesky virulent pathogens. Sort of like the planet-eaters immune system cleanses the planet before it eats it. [Answer] No temperature is feasible. This is because by the time the Earth becomes fully uninhabitable at the rate of heating stated by the OP, humans could build rockets to escape the Earth and colonize the other stellar bodies in the Solar system. This would potentially include the planet-eating monsters, and it might include any other stellar bodies that the planet-eaters have decided not to eat (e.g. possibly including asteroids or comets). Potentially quite large rockets, too, since it's entirely possible that the Nuclear Test Ban Treaty will be torn up to facilitate the development of Orion Drive-style nuclear pulse rockets, which could carry 6000 tons to the moon and back on one tank of fuel using 1960s technology. Additionally, while the temperature outside might rapidly become uninhabitable, it's entirely possible for humanity to build large climate-controlled structures to live in while this construction work is underway, along with hostile environment suits to let them walk around in temperatures that would otherwise kill them. ]
[Question] [ Is it possible for there to be a "solar system" of sorts with a black hole and a few suns orbiting around it? Could that system be stable and (if so) would it be possible for some civilization(s) to exist on planets orbiting the stars and the black hole? [Answer] # Problem 1: The supernova The first concern I have is one that [Zeiss Ikon's answer](https://worldbuilding.stackexchange.com/a/131861/627) discusses. To form a black hole, you need some sort of energetic event, likely a supernova. However, a supernova releases three extremely problematic sources of energy: * High-energy photons, like gamma rays, that have the potential to strip away the atmosphere of any pre-existing planets in the vicinity - or, at the very least, to remove their ozone layers. * Several solar masses worth of hot, fast-moving ejecta (think something on the order of $\sim$10,000 km/s, heating up any nearby gas as it travels outwards. Again, not super awesome for planets and their atmospheres. * A flood of neutrinos, carrying away the bulk of the explosion's energy. [They're really not phenomenal.](https://what-if.xkcd.com/73/) That said, I'm unsure of how neutrino heating in an atmosphere would go. Plus, this supernova's progenitor was probably a massive star, and massive stars have strong stellar winds (on the order of $\sim$1000-2000 km/s), which also have the potential to ablate atmospheres. We might be able to form a black hole without a supernova, via a situation called a [failed supernova](https://en.wikipedia.org/wiki/Failed_supernova). The idea is that a sudden emission of neutrinos prior to core collapse could carry away enough to mass-energy to substantially reduce the luminous energy output of the explosion. The collapse would still create a burst of energy, but it might be much less deadly than a normal supernova, perhaps even preserving the planet's atmosphere, if it already existed. Now, we haven't gotten rid of the whole neutrino problem; in fact, we've increased it. However, again, perhaps the energy transfer isn't as intense as I think it might be. I'll need to do some reading. # Problem 2: Fun with orbits You also have to consider that the orbits of the system could get pretty funky. Asymmetry in the explosion could create an effect similar to a [pulsar kick](https://en.wikipedia.org/wiki/Pulsar_kick), propelling the black hole at several hundred kilometers per second. If it traveled slow enough to remain gravitationally bound to the system, it might be traveling in a fairly elliptical orbit, and if you want to have multiple other stars, you'd have to worry about their orbits being disrupted. Additionally, plenty of mass is lost during a supernova - most of the progenitor's mass, in many cases. This, too, will disrupt the orbits. It would be interesting to model this to see exactly what would happen, and if the effects would indeed be problematic. Systems with three or more stars are already kinda sensitive to dramatic enough perturbations - and believe me, this mass-loss would be quite the perturbation! One possible solution would be for the planet-hosting star and the black hole to come together after the supernova occurs - in other words, for one to gravitationally capture the other. This requires a third body to mediate the interaction - so, for instance, if the black hole interacted with a binary star, one of the stars would have to be ejected for the other to become bound to the black hole. This, of course, presents more orbital difficulties. A three-body encounter would likely disrupt the planet's orbit, if it had already formed. If it formed after the encounter - well, that demands explanation. Perhaps it formed from the debris disk left behind by the progenitor star. But then why would it orbit the secondary star, not the black hole? That, as far as I can see, remains a problem. Capturing the planet, as Cadence suggested, might be a way around it, but the orbital dynamics would be . . . delicate. [Answer] Yes. You can take binary or trinary star systems and swap one of the stars for a black hole and nothing changes in the orbital dynamics. Depending on the layout of the solar system planets can orbit the stars, the black hole, or some mixture of the above. Some of those planets could be in the habitable zone (liquid water). And some of those planets could develop intelligent life. We don't know what the probability of most of thees steps is (especially the last one) but we know they are all plausible. [Answer] Maybe. The only mechanisms we know that can form a stellar mass black hole (a few to a few tens of times the mass of our sun) are neutron star mergers (seemingly very rare) and supernova explosions. Either of these are extremely energetic events, and since planets apparently form as part of stellar formation, all the planets in the system will exist at the time of the supernova that created the black hole (neutron stars also form in supernovae, but the time for two to decay orbits and merge would probably exceed the viable lifetime of a habitable planet). A supernova within a few light years, never mind in the same gravity bound star system, would likely sterilize any existing planets; one within a fraction of a light year (say, even a 500 year orbit) would probably strip the atmosphere from a rocky planet, almost certainly ruining it for future re-evolution of life. Such an event would very certainly destroy any existing civilization that couldn't flee well ahead of time. You'd need a situation where a planet manages to at least retain an atmosphere (and liquid water or other suitable liquid solvent, say liquid hydrocarbons as on Titan) for life to have a chance to re-evolve, or even for a planet to be suitable for recolonization after the black hole forms. No, not impossible -- the universe is a big place -- but pretty unlikely. [Answer] The situation might evolve in a globular cluster where stars ar fairly close together. IF a black hole in moving through the cluster at the right velocity, it might attract stars into an orbital arrangement with the black hole in the centre, and the planetary systems of the stars remaining in orbit around them. This is going to be a delicate arrangement, since the act of gravitationally attracting the star to the black hole is likely to cause disruptions in the orbits of the planets, kicking planets out of habitable zones, or alternatively moving them into habitable zones. The likely look of such a system from far enough away will be similar to a comet, with the "tail" being billions of comets and Oort cloud objects from the various star systems, followed by some ejected planets, then the stars and finally the black hole itself, likely visible by the accretion disc made up of the relatively denser dust and interstellar gas from the globular cluster. [![enter image description here](https://i.stack.imgur.com/LuOeC.jpg)](https://i.stack.imgur.com/LuOeC.jpg) Imagine the bright nucleus is the accretion disc of the black hole, and the "tail" is the objects scattered and pulled along by the black hole. The star systems with planets would be about 1/3 of the way back from the nucleus, any closer and they would be roasted by the energy of the accretion disc The sky from these planets will be interesting. On a planet you still have your sun and other planets (likely in rather eccentric orbits), with several other stars nearby and an amazingly bright object high above the plane of the ecliptic. The constellations will change rapidly (say over the lifetime of a civilization), constellations visible in the early Roman Empire will be long gone by the collapse of the Empire because of the orbit of the stars around the black hole. [Answer] If mankind created an artificial black hole that eats earth, then it would have the mass of earth. It would be in the same orbit as earth was and there shouldn't be any big change. So maybe if a terrible accident happened to a colonized planet or if the greatest mass murder of all history happened during an interplanetary war, then I guess it could. [Answer] It is not only possible, it is normal: Earth is a planet orbiting a star which is orbiting the black hole at the center of our galaxy. [Answer] A black hole, the likely size to act as a central mass, with orbiting suns, would likely be the result of a supernovae, which would have a typical lower size of about 25 solar masses. The nearby few suns would likely have great orbital distances and/or high orbital velocities. Eventually the black hole will increase in gravitational draw, and then slowly the suns would be sucked in. In other words, this scenario is an unstable one. Additionally, it would involve extremely large orbital distances and velocities. Planets orbiting would have to have high orbital velocities, and like the suns might be subject to substantial tidal forces. Higher orbital velocities incur a higher probability of matter accumulation, which is incompatible with the stability to support life. So not very likely. Addendum: Stated differently, the probabilities for "solar systems" of multiple stars, referencing the original poster term of "a few suns" orbiting around a black hole, carries the implication of a larger black hole, and since the observed black holes are in the 10 to 100 solar mass region, with 25 being near the modal for the distribution (and perhaps for other reasons as well), the larger solar mass black holes would permit "orbiting around" of a few suns. Secondly, in the Milky Way it is estimated that most stars, perhaps 85 percent, are red dwarfs, which are generally about 0.2 solar mass. Additionally, estimates (some are less) of the red dwarfs have stellar companions. So to have a black hole, with an orbiting set of a few suns orbiting it, appears to be a rather improbable event, given our contemporary understanding of stellar demographics. However, things do not end there. To have a system of planets orbiting the back hole with a few suns orbiting it stellar collection, would likely require large orbital distances and/or high orbital speeds, as the central mass would be rather high. That is, not the tiniest black hole, and then again a few suns in orbit. So we are talking a large footprint for the resulting solar system. The original poster asks if civilizations, which I suppose means "life as we know it" to be inhabiting one or more of those planets. Now the collection of those few suns and the black hole must be distributed in a rather uniform manner to permit somewhat uniform insolation of the possible planet in the green zone. The probabilities keep dwindling. So we have a mid-sized black hole, with a few suns, somewhat uniformly orbiting it, and those suns should not be of the ever popular red dwarf type, and somehow this arrangement will provide somewhat uniform insolation to a planet sitting in the green zone of the system. COULD something like this exist? Who could say definitely yes or no? However the majority of solar systems are binary, so that tips the scale towards systems of more than one central star. However, the effects of multiple solar mass bodies tends to have other effects which enter into consideration. Accretion rates, are likely to cause a doubling of mass from tidally disrupted stars (2x10^10 years approx), and for gravitational diffusion (2x10^9 years approx). There is much more to factor in, but the doubling of the black hole mass within the lifetime of a planet such as earth is real, and would have disastrous effects. For example, the luminous flux of the resulting suns would be compromised, changing drastically the green zone. Additionally the ever cycling tidal forces of the multiple stars would likely create a substantial fluidity of the planet structures. This might also affect the development of civilization. A few suns in addition to having the right irradiance, would also have to have rather regular orbits, as eccentricity would adversely impact consistent planetary insolation. So summarizing this, a central mass black hole, orbited by a few suns, with sufficient and uniform insolance on a planet in a green zone, which would be presumably free from excessive tidal forces, and having that central mass black hole be stable and not substantially accumulating mass from accretion or other effects in what promises to be a region ripe with tidal forces and gravitational diffusion, seems rather unlikely. ]
[Question] [ Imagine alien prospector wanting to build "space highway" through our solar system. There could be another route, but the one leading to our system is "the best" Such prospector also wants to use Jupiter orbit as "space gas station, with bar". Jupiter could be used not only because of its gravitational attributes, but simply because it would provide a stunning view for spacecrafts passing by. The alien law states only one clause: If in given solar system is a planet with a civilisation which can detonate an atomic bomb, you have to have an agreement of such planet. In our case, it would mean, that "space highway" has to be voted by UN and approved by majority of votes of all United Nations countries. The prospector is willing to trade, offering to humanity new, shiny space station packed with cutting edge tech (from Earth point view). There would be nothing unknown to humanity, but imagine onboard computer having capabilities of top 500 supercomputer but also being shielded from space environment. Also, prospector thinks, that if humanity knows, that if they make it to such "space bar" on their own, they could buy things from gas pump or such bar. And there are going to be "alien technologies" The biggest drawback is, that our alien has to have a majority of Earth agreeing with such "space bar" and he would like Earth to agree in next 10 years. If agreement is not met, next detour is around Proxima Centauri solar system. How should our alien proceed? He wants to approach us "tomorrow" (Earth current day) Some background Aliens see us the same way as we see "low paid jobs nationality." If you are American, imagine meeting Mexican. For Germans it would be Turkish and for Czechs it is Ukrainians. They would treat us the same way as we treat them: * Do not generally care how Earth lives and what is its technical development * Do not care who is representant of Earth * "All earth people are the same" racist approach * Do not care what alien technology is going to do with Earth If someone from Earth manages it to this space gas station, they are going to be approached the same way as American would approach someone from Mexico: > > "Uh, I am new here. How can I buy stuff?" > > > * "Space credits, dude." > > > "And how do I get some?"' > > > * "Sorry, I have no change right now." > > > "How do I apply for membership in space union?" > > > * "Just 25 light years away there is space union branch." > > > "And who is your leader?" > > > * "Xulguth the Great, duh! You never heard of him?" > > > (And so on. Basically assume same level of racism and racial profiling as you would do in your normal day when meeting someone from "foreign workers" nationality) Also, you may assume, that all aliens posses "universal translator" device which allow them to understand every language which has been ever broadcasted on TV [Answer] You question makes two stipulations: > > * The alien law states only one clause: If in [the] given solar system [there] is a planet with a civilisation [that] can detonate an atomic bomb, you have to have an agreement [with] such planet. > * Aliens see us the same way as we see [people from poorer countries]. > > > The conclusion you come to is that : > > In our case it would mean that [the] "space highway" has to be [...] approved by [a] majority [of UN member states]. > > > I disagree. Let's take the example of the [Panama Canal](http://en.wikipedia.org/wiki/Panama_Canal#U.S._acquisition). The US offered to buy the land for the canal from the Colombian government, but their Senate refused the deal. So, the US simply decided that some Panamanian rebels who were willing to deal were the 'legitimate' government of Panama, and supported them in overthrowing Colombian control of Panama. This case would be even simpler. The aliens would just build their highway and take Jupiter. We have no way to stop them, and we aren't even living there. If there is a public outcry on the aliens' home planet, their government simply explains the situation one of two ways: * "China is totally OK with this, and they're the real, legitimate government of Earth. In fact, we're sending them a couple of shipments of lasguns to support their bid for independence from the evil, backwards, illegitimate nations US and Russia." * "Wow, we had no idea that Earth had nuclear weapons, seeing as they are so backward and simple-minded. We'll launch an investigative committee to advise us how we can avoid this in the future. They should come back to us with a decision in 10-15 years. In the meantime, visit the brand new Jupiter station today!" Those with power don't have to obey the rules. In this case, the aliens have the power so they can do whatever they want. [Answer] They pull into orbit. Analyze our broadcasts to work out universal translator software. Broadcast out a signal. "We intend to build this outside Jupiter. Here are advantages for you. Here is the license we require from you. Here is what we are willing to offer in return" in every language. From there it just becomes standard diplomacy and negotiations. The aliens as you describe them are not actively harmful to earth so would probably agree reasonable terms and then move on. The UN would no doubt be paranoid and do a lot of arguing but the simple fact that the aliens are willing to deal in the first place rather than just move in without permission would be a huge sign in their favor. After all if they set up anything they liked around Jupiter there really is nothing we could do about it! The ripple effects through earth society though at confirmation of alien life, and potential scientific or other breakthroughs that come from the contact, would be huge. That is where the main effects would be. Even if the aliens don't sell us any technology as part of the deal we're still going to learn a lot just from seeing what and how they do. Sometimes just knowing that something is possible is half of the work needed to find out how to do it. [Answer] You said they would give us a 'shiny new, cutting edge space station' in return for trade privileges. Now, assuming we have a leadership with rudimentary intelligence (and that's a big stretch) the United Nations would approve the deal. If the aliens build a highway and pit stop at Jupiter it would really benefit us more than harm us. The shiny new space station will probably be placed in orbit around Earth. From there we can reverse engineer the technology and mass produce it. This could solve our energy problem (might have clean energy) and would make colonization of the Solar System easier. Just stuff people and supplies into our station, send a quick alert to the aliens that we call dibs on Mars and send them to start a colony. It would probably be more complicated than that, but you get my point. We should also ensure that the contract says what we think it does (e.g. Make sure there is no 'we get to "enlist your cooperation"' or 'We get free reign on your planetary resources' clause. [Answer] # SEA, EIA, and PCR The requirements that the United Nations - and EU - would (okay... should) request is that the Aliens undertake a Strategic Environmental Assessment (SEA) prior to any development. This examines and tracks any decision-making that could have cultural or environmental impacts. It doesn't enforce, it just recommends and tracks decisions. Next, prior to construction, they should undertake an Environmental Impact Assessment (EIA), which we call an EIS in the states. This identifies impacts and decides how to mitigate the impacts on the space and culture they're affecting. Finally, although maybe not in this case, the Aliens must undertake a Preliminary Cultural Review (PCR). If there are impacts on us, they must identify them, and show how to mitigate or compensate for these impacts. That is what the UN and EU would require. From the results of those studies, the UN could recommend that the Aliens proceed with development, and there would be a set number of days for anyone to comment. Information on the project will be displayed in Geneva only, for anyone on Earth & Jupiter and elsewhere to provide public input :) [Answer] Even if the aliens do not care what the presence of this technology will do to Earth, they would be well advised to provide some sort of evidence that it won't be grossly harmful in order to keep the natives from causing trouble. (Also in order to keep those do-gooders in the Society for the Protection of Primitive Species off their backs.) So they should provide an outline of the science involved. If possible get (or fake) glowing testimonials from other species who've already agreed to similar projects. As for who to talk to, they should let slip that any of the local chiefs who sign up will obviously be entitled to a few technological goodies right now - the equivalent of the string of beads allegedly used by a Dutch trader to buy Manhattan Island. [Answer] I think the hard part would be each nation wanting to make sure they got a piece of the pie, and it might be hard to do that with a single space station and set of equipment. They'll be fighting over it like a bunch of parents fighting over the last Tickle Me Elmo. At some point some idiot will say "If I can't have it no one will" and shoot it down. What would be a lot better would be the plans and theory for some technology that could be shared every where. Clean cold fusion, replicators, teleportation... Something that would help bring the poor nations up to a level closer to the rich nations, and not destroy the planet in the process. Granted, the space station could have those things on it, but the reverse engineering would be handled by the rich nation governments and multinational corporations (since they have the resources to do something like that) and the poor nations would (rightly) be afraid that the technology would be limited and controlled. Say Lockhead Martin got the right to reverse engineer the replicator, then they get to build and sell them to anyone that can afford to buy one, at a 100 million dollars apiece, and no one else gets to make one, and anyone that tries gets sued... Some people would say that it's important not to disturb the status quo, but those people are the ones that are making all the money from the way things are now. It would be a disaster for everyone else. Also, any agreement should be a lease for the space around Jupiter, not sale outright. Something like the Chinese did with Britain for Hong Kong with the [99 year lease](http://en.wikipedia.org/wiki/99-year_lease). [Answer] When earth finds out about the existence of aliens their will be a lot of sci fi fueled panic. Given that the aliens could technically blow us to smithereens humanity will agree on whatever the aliens want ( almost ). Of course they agree, we would agree to almost anything that wouldn't destroy us if we don't know that the aliens follow their own rules. The most valuable thing humanity can gain is clues to far superior tech. Many probes are sent out towards Jupiter to monitor their activity ( unless they object to this. ) A huge range of instruments are sent towards the aliens or aimed at them from earth. ( fly through their exhaust trail to help work out interstellar engines. ) A manned mission will probably be attempted. Given that aliens do not have (identical to) earth manufacturing capabilities the tech they give us may be nano fabricated. In this case finding a single broken nanobot trapped in something and analyzing it with an atomic microscope will let us build our own version from the same principles far more easily. I therefore expect that the space station would be cut into samples and analyzed, at least some of the less vital or easy to replace parts. If you were tasked to build a "vacuum tube" computer for the 1940's you might well present them with a bunch of useless vacuum tubes wasting energy and small microchip hidden in the frame. We can expect, or at least suspect such a more efficient component and a "do nothing" from the aliens as well. Finding them could also be worthwhile. Maybe the solar panels are fake and their is a tiny fusion reactor hidden in the hull? Expect humans to accept and scrutinize the aliens in detail. [Answer] I wasn't aware that the uninhabited planet of Jupiter was owned by anyone. How would such a transaction occur in the first place? I believe it falls under the heading of International waters legally speaking. Anybody who colonized the planet and claimed themselves a sovereign planet would be the owners. ]
[Question] [ Disregarding actually acquiring material and any time/effort required for the manufacturing process, would titanium cutting weapons (e.g. swords and daggers) be more effective than steel weaponry? [Answer] Let's get one thing out of the way first: 'steel' isn't a single substance - it's a term for 'an alloy of mostly iron, with some carbon and maybe some other stuff as well'. There are a lot of types of steel, with a fairly large range of properties. Titanium could be a single substance (it's an element, not automatically an alloy), but allowing alloys for one side of the comparison but not the other seems a bit unfair. If we are allowing titanium alloys, then there's also a range of properties available here as well. So the accurate answer is it depends on which types of steel and titanium you're talking about. If you want titanium weapons, you could definitely set up a situation where the available titanium alloys beat the available steels, but you could equally do the opposite as well. Still, we can also do a comparison of some kind of 'average' for both sides, so let's talk about that. ## Titanium generally has similar performance to steel at a lower weight The common perception of titanium is that it's really strong, but it's more accurate to say that it's really strong for its weight. If you have a piece of titanium and a piece of steel the same size, the titanium will be about half the weight. Comparing strength depends on which alloys we're talking about, but it's likely that a good steel will be a bit stronger, for some definition of stronger. NixonCranium mentions that titanium is more brittle than steel, but it's more complicated than that - with 100% pure metallic titanium the problem is actually going to be that it's too flexible rather than too brittle. Getting 100% pure titanium is very expensive, though, and even a tiny amount of oxygen in the mix causes it to be brittle compared to steel. If you can produce pure enough metal, though, it forms a protective titanium oxide skin in much the same way aluminium does - it won't be automatically ruined by an oxygen atmosphere once it is finished. Overall, that means it's likely that the titanium will fail in some way before the steel does, whether that means breaking or bending. So what does that mean for titanium weapons? ## Titanium blunt weapons are trash I know the question asks about edged weapons, but let's cover this one as well. For maces, warhammers or similar, titanium is just too light. These weapons deal damage through their weight, so a light metal is bad. Similar logic goes for axes, although to a lesser extent. However, if you want the classic fantasy dwarven axe with a massive blade, titanium suddenly looks better - those are actually unrealistically heavy when made from steel so the titanium could make them more plausible. ## Edged weapons need some form of titanium alloy Pure metallic titanium isn't very good at holding an edge, so hardening is necessary (and the hardening is going to make it more brittle). This doesn't have to be the full weapon - hardening the edge and leaving the body flexible is a well respected tradition in weapon-smithing - but something needs to be done. ## Titanium is probably a poor choice for the army, but could potentially be great for civilian weapons. A second effect of the low weight is going to be poor anti-armour performance, especially against plate armour. If you want to kill someone in plate, you basically have to use brute force - and a lighter weapon is worse here. This is why the age of plate mail is also the age of two-handed weapons and maces - you need the weight or your strikes just bounce off harmlessly. None of that is what a titanium weapon would be good at - light is for fast, which matters most in an unarmoured fight where the first strike that lands probably ends it. The people who want titanium weapons are skilled rapier duellists and knife-wielding assassins. Neither of these expect to face armour, and neither are trying to use their weapons for a full-force block against heavy attacks (even if we do assume titanium is brittle/weak compared to steel, it's definitely strong enough for a rapier-on-rapier parry). What they are trying to do is shank the other guy as fast as possible, so lighter is better. ## Bonus: titanium could make really good armour Again, not directly part of the question but we'll cover it anyway: light and strong is exactly what you want in armour. It's not necessarily the best choice for heavy armour (the fantasy adamantine equivalent would probably still be a really high-end steel) but it should do well in the medium armour niche where you want decent protection but also still need good mobility as well (basically, it's a mithril equivalent). [Answer] No, titanium bladed weapons would not be superior to steel bladed weapons of any decent quality. While titanium is appealing on its face due to the fact that it does not rust and is non magnetic (hence some submarine hulls are made out of it), and it’s greater hardness, there is a fundamentally fatal flaw; titanium is more brittle than steel. Being more brittle than steel is an unacceptable weakness for melee combat against enemies who have steel weapons and armor. You do not want your sword to snap in battle. The only reason you’d want titanium is if you plan on using it in saltwater or in an environment where it’s critical that it’s non magnetic. P.S. I have titanium knives and axes and they’re cool to have. I don’t worry about rust but I’m not getting into a fight where I have to parry against steel. ]
[Question] [ I've been kicking around story ideas about how much different this pandemic would be if human beings could actually see the virus on our hands, on surfaces, in the air, etc. This lead me to wonder: can a human head host eyes with sufficient resolution to be able to see bacteria? How about viruses? To do smaller and smaller resolutions, my understanding is that you need greater precision in the lens. Is there some fundamental biological limit we would hit trying to achieve such perfection? What about mechanical replacements? Is there enough space in a human head for the cameras/machinery needed to do such resolution? In summary, is there anything that prevents humans from having both the ability to see as well as we do today for macroscale objects and the ability to see all the tiny bits of life on all the surfaces around us? [Answer] ## The limitations of microscopy: I work with microscopes all the time, viewing bacteria (Gram stains). There are a couple of issues at play here that would seriously disrupt the ability of a person to see bacteria in the way you are describing. First, microscopes focus on things in a very specific distance to be precise. It would be possible to have a big-ish microscope essentially head-mounted on a person, and flip the objective out of the way, so this isn't a total deal breaker. It just means you'd need to be able to hold the head very still and at the perfect distance. Even the vibration of a running refrigerator nearby will throw off the focus. Second, at the focus levels you're needing to see bacteria, the light scatter is such that in a hospital lab, I apply oil to the sample so the change in density between the air and the lens doesn't scatter the light. You'd need to be applying oil and essentially plastering your optics right up to what you wanted to see, or else it would be too fuzzy. additionally, bacteria are tiny things in an environment FILLED with tiny things that look a bit like bacteria. Not to mention that the environment is FILLED with otherwise harmless bacteria. To get around this, we Gram stain - use stains that selectively colorize the cell walls of bacteria so we can even see that they are there and what shapes they are (to distinguish approximately what kind of bacteria they are; a complex series of tests verifies what kind they are, and if they are pathogenic). The actual Gram stain is a relatively imprecise tool, but quick. Finally, viruses are generally so small that you need an electron microscope to visualize them. While it might someday be possible (but totally impractical) to place an electron microscope on a person's head, the other issues are all magnified (pardon the Dad joke) a thousand-fold with this technique. Not to mention that most of these images are actually visualizing thin coatings of metal bombarded on to the objects being viewed rather than the actual objects themselves. [Answer] > > can a human head host eyes with sufficient resolution to be able to see bacteria? How about viruses? To do smaller and smaller resolutions, my understanding is that you need greater precision in the lens > > > It would not be enough. The problem here is that when you "see" a very small object, what you actually see is the light reflected by that object. The smallest the object, the less light it reflects in absolute terms. That is why microscopes use a light source to light up the sample. This is not possible with just an eye. What you could do is have a laser-like illuminator target an area, and gather the light scattered by that. You probably don't want coherent light though, so no laser, just a focused light source. Then you'd have the problem of stabilizing the image. Imagine looking at a bacterium one meter distant; a bacterium is maybe two microns in diameter. One micron at one meter is on the order of two arcseconds; this means that even the minutest wobble of the head (due to heartbeat, let alone breathing) would make the focused area sweep away. Some really clever image stabilization technique would be needed. These are the first difficulties that spring to my mind, but this is totally not my area, so there could be worse traps lurking in the concept. As to not give up normal vision, that's no problem. You could have microscopic vision replace on demand the vision out of one eye. With a little training it's perfectly possible to be looking at two different scenes from the two eyes at the same time; the brain learns to concentrate on whichever detail catches your attention, but does not go blind to the other eye. [Answer] The lens in the human eye would not allow it, even if it would be perfect Note: below is about limits of a perfect lens. Answers/comments that take the wavelength of visible light into account are right, of course.. in fact, no optical device for visible light will be able to show corona viruses ! * Focal distance. This property limits the minimal view distance to objects that can be sharp. For the human eye, depending on age, it is around 30-40mm in practice and 17 mm theoretically. At that distance, the retina will never have enough cells to see viruses. * MTF. For a lens geometry, you also have an built-in theoretical limit on resolution. The maximum MTF is the resolution of the ideal lens and it only depends on the wavelength and on the curvature, size and refraction index of the lens itself. Our eyes do contain a high quality lens, but the size of that lens and its power (about 20D) will not allow us to discern particles below ca 0.02mm at 17mm focal distance. Even the perfect android robot with endless retina resolution, having a single diamond eye lens shaped like ours, would not be able to see most bacteria. Let alone viruses.. [Answer] Humans can already detect objects down to the nano-scale using their touch [(ref)](https://www.sciencedaily.com/releases/2013/09/130916110853.htm). You might like to play with the idea of "seeing" being a bit broader and instead use sensory inputs like touch, or smell (à la suggested superior olfactory senses of canines). Secondly there is a quite a bit of research that shows the dose of a virus or bacteria is important to survival / damage e.g. [ref](https://link.springer.com/article/10.1007/s12393-020-09249-6) (use search times like: `dose response LD50 bacteria`). Clean surfaces don't necessarily need to be 100% clean as removing 99% of the microorganisms still might leave tens, thousands or millions but might downgrade what would be a fatal infection to a serious, serious to mild, mild to asymptomatic. And or a communicable (transmissible) to non-communicable. Finally and perhaps most usefully: what if we could see in UV light like various insects like bees and also not be overly harmed by it (e.g. higher melanin)? UV light is absorbed by various chemical bonds; which is why it can then break them / generate free radicals that can damage / kill the organism. But this means it also "looks" different due to difference reflectance / absorbance. Secondly UV light, upon being absorbed can be re-emitted at a different wavelength through fluorescence. [(ref)](https://www.independent.co.uk/life-style/coronavirus-wash-hands-correctly-photos-black-light-germs-a9384321.html) ... of course that air is also stuffed full of dust, pollen, mould spores etc so this might not be very useful after all. [Answer] Yes, in some sense Do not repeat that thypical mistake of genetically modified creatures adapting for each and everyone planet. Use google glasses or equivalent and appropriate, technology based sensors and convert their signals to visual information. Optical means for shure do not help you see vuruses, and apparently you have no idea how messy skin would look like under a microscope, and that many bacterias are part of our symbiosis. But what you are looking for, partially, called [AFM](https://en.m.wikipedia.org/wiki/Atomic_force_microscopy) which is basically a micro wisker scanning a surface. So it can be not like you solve the problem of how much optical component you can squish in someones head, but by some technology you have array of such wiskers on a tip of ones finger and you move it across some surface and get the information, already filtered for features you are looking for. It may be part of efforts of controlling spreading and elemination antibiotic resistant bacterias, and other microbiological stuff, but it does not describe it in full - how it should be done and alone it is definitely not an ultimate answer for the situation. Capacities of our bodies aren't that bad and it can be used as a detector, or part of the detector - I mean body contains tools which can be used on cellular level and it just needs better and digital/chemical interface. As potencial technology - nanomachines son - really that could be useful, a lot of things can be done with our ability to work more freely in confines of few microns. Including that we could eliminate all harmfull microbiological materials, in a way which they can't adapt for, and/or create additioanl barriers for them, and bug fix the responses of immune system etc. So what you are looking for is nanotech. [Answer] Assuming the fact that no one will ever remove one of his working eyes to see if a plate is full of bacteria, the reply is - everything is already full of bacteria. Probably will be more usefull to distinguish between kind of bacteria. Assuming you know how to distinguish the bacteria, the minimal resolution is a 400x magnification. It can be done by a normal (normal by scientist range) microscope lab. Your skull is not enough to host such optics, and we don't know any being able to do a 400x magnification (1000x if you want details). Some predator is able to spot more details but not to "zoom in". Anyway, once you own such magnification by some special mean, there's no issue for your optical nerves to transfer the stimulation to the brain - so you'll see the figure. Does this could help against pandemics? If every human being was able to distinguish evil bacteria on top of a surface, probably so. To be honest, I can't figure out how to write a pandemic story if that skill or technology was developed for more than two generations. There will be no contagion at all - the actual problem we have with viruses is we cannot scan the entire world surface - having such granularity of detection is in fact what we first did with COVID! Good luck. (on a side note: I've spoken just of bacteria, as viruses work differently, but if your story can assume people can see bacteria, is already "fantasy" enough to see viruses the same). (side note 2: now that I'm thinking about... why the sense of view?!? It's not efficient. You can create an organ that work like a nose, inspire and have a reaction. A natural buffer. That's what I'll develop!) ]
[Question] [ I have been making a future colonization scenario where people have vast colonies on Mars and cloud top bases on Venus. These things are unbelievably large. I've already thought of a way to travel between these on Mars, but Venus is another issue. Could you use a common passenger jet (most likely modified to use solar power, however) to traverse these large expanses of atmosphere? How about any other form of common air travel? Helicopters? Gliders? [Answer] While in theory the atmospheric pressures and temperatures in the upper regions of Venus' atmosphere are more conducive to the operation of aircraft, you still have a problem; sulphur dioxide. This is one of the emissions that [grounds planes during volcanic eruptions](https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JD022070) meaning that even if you can fly the plane there, the maintenance costs are likely to be prohibitive. That said, given the density and the nature of the gases in the Venusian atmosphere, you don't need aircraft to fly between bases. You could literally float. The idea behind the [cloud cities of Venus](https://en.wikipedia.org/wiki/Colonization_of_Venus#Aerostat_habitats_and_floating_cities) is that molecular oxygen, nitrogen and other gases that humans need for a healthy life, particularly at the temperatures we operate at, would actually float in the atmosphere at a particular altitude because the density of the super heated CO2 is sufficient to support it. So, you basically can build a lightweight 'bubble' of the gases we breathe and put a city on the floor of it and it would float around Venus. Obviously this is a simplification, but it's functionally correct. The point being, you could do the same thing with your aircraft or transport vehicles. Basically create a series of mobile bubbles, fill them with breatheable air, give them propellers and the like to move about, and you've literally got an airship in which the crew, passengers and goods can all safely reside in the air envelope - you don't need hydrogen or helium to make the craft lighter, because in that environment normal air is already lighter. This would actually be a failsafe for all but catastrophic breaches of the air envelope because even if you run out of power, you float until someone picks you up or tows you in. The other advantage of this of course is that your airships are likely to be capable of moving larger cargoes and passenger lists than a conventional 747. They would be more like the trains of the Venusian sky. [Answer] Obvious problem number 1: there's no free oxygen in Venus' atmosphere, so you can't run any kind of combustion engine. Lets assume you're using some other kind of engine though, though I won't specify which. Venus at low altitude is very, very hot and has very high air pressure. Your aircraft would disintegrate in short order. Once you get to an altitude of 50km though, atmospheric pressure is nearly the same as that found on the surface of Earth... about 1.07 atmospheres, though it is a little warm at 75 degrees C. Go a few kilometres higher and you'll get half an atmosphere of pressure and a balmy 27 degrees air temperature. At 60km conditions start to look a little more like they would for a Boeing 747 at cruising altitude on earth, though quite a lot warmer. You'd still have to contend with a possibly very corrosive atmosphere though... there's quite a lot of sulphuric acid in Venus' atmosphere, but if you avoid clouds you might be OK but it would be best to thoroughly corrosion-proof everything. Wind speeds are quite strong up there too, but windspeeds at high altitude on Earth can also be pretty brisk and that hasn't stopped commercial flights being entirely practical and largely safe. Any form of flight that would work on earth and not need oxygen for the engines to work should function just fine. I'm not sure a solar powered passenger jet would work, though... I'm not about to run the numbers myself, but I think the available surface area is too low to provide the same amount of power those four big gas turbines would on Earth, and even at 60km altitude there can be thick cloud cover. If you don't have compact and lightweight fusion power, you'll have to scale back the cruising speeds of your aircraft somewhat. Maybe electric props or fans with fuel cells as the power source might work. At 50km you can make bouyant balloons filled with human-breathable gas, so as long as you have some good air conditioning maybe zeppelins would work for you... [Answer] In a direct answer to your question no you could not use a common passenger jet unmodified. Firstly the atmosphere would contain a lot of sulphur dioxide and a small amount of water creating sulphuric acid which would rapidly corrode the structure of the jet. That said a jet could reasonably easily be modified to incorporate plastic coatings such as polytetrafluorethylene to resolve that issue. But a bigger issue would be propulsion. How would the structure be moved in the atmosphere as no oxygen is present for combustion? [Answer] At the altitude the cloud cities would be situated the atmospheric density is similar to that at ground level, or ,say, the troposphere, the lack of oxygen knocks out any possible jet aircraft. While solar-powered aircraft can be possible. They will be too light and too fragile. This is a major potential problem. Remember the Hellish abyss of the Venusian atmosphere lies down below. The most probable aircraft for travelling between cloud cities will be nuclear-electric powered helicopters or propeller-driven fixed wing aircraft. Pressurization and airtight compartments will be an absolutely necessary to ensure they can breath air containing oxygen. This will keep out the sulphuric acid in the clouds and aircraft will have be acid-proof. Not totally infeasible, But Boeing 747's cruising Venusian skies, definitely not. Jets are also definitely out. But propeller or rotor aircraft with suitable power sources, presumably nuclear instead of solar, are quite feasible. ]
[Question] [ I want the surface of my fantasy planet to be made hostile every few thousand years for long enough to make every species go extinct that breeds on land. The easiest explanation seems to be other planets' gravitation, causing every volcano to erupt at the same time when everything is in a certain constellation. Ash will cover the sun and everything freezes for some time. What size, distance, and constellation would the planets have to be to support such a system? Hello again. My English isn't that great. That's why I didn't want to make the description too long. Here I go anyway: With "extinction" I meant that they wouldn't be able to breed on land in this period of time. Many creatures are amphibian, others are hardly considered "living" in the first place and then there are some species that have second DNA which can survive for a long time and then recreate the old species. There are also creatures that live and hunt in underground caves. They come to the surface when the climate changes and "make sure" that nothing stays the same. A human-like species has to rediscover scripture and can find relics from old civilisations... [Answer] Your assumption is reasonable, as Tidal Heating is the reason that [Io is the most geologically active body in our Solar System](https://en.wikipedia.org/wiki/Tidal_heating_of_Io). Although, a problem with using [Tidal heating](https://en.wikipedia.org/wiki/Tidal_heating) is that the energy is drawn from the gravitational energy, so - without additional planets involved - your system will eventually decay into [circular orbits](https://en.wikipedia.org/wiki/Tidal_circularization) and no longer produce the heating. But, that can be somewhat mitigated with other massive objects in the system to 'kick' your planets back into an elliptical orbit Since you want this to be a long process, I would suggest looking at [Neptune](https://en.wikipedia.org/wiki/Neptune) and [Pluto](https://en.wikipedia.org/wiki/Pluto#Relationship_with_Neptune), which periodically swap order - for example, from 1979 to 1999, Neptune was actually farther from the sun than Pluto. ("My very efficient memory just stores up planets nine") Pluto takes 248 years to complete an orbit, and Neptune takes 165 years, so they reach the closest point in a cycle of about 495 years Because these are sufficiently separated vertically, then can never get closer to each other than 8AU (1AU is the distance from Earth to the Sun) - however, your planets can get closer than that. Also, when 1 planet is at one of the intersection points, the other planet may be elsewhere in its orbit. All you need is that every 20,000 years the planets both reach the intersection point at about the same time, and pass close enough to stress each other. To magnify the effects, your inhabited planet is probably the smaller of the pair. When stretched and squished, then this means: * The interior of the planet is heated up, providing plenty of magma for volcanos * The crust of the planet is put under strain, providing plenty of opportunities for earthquakes, and resulting tsunamis In terms of stability? Both the Jupiter-Io and the Neptune-Pluto systems are stable. You will need other planets in the system to help, but with only 1 interaction every 20,000 years this does not need a massive amount of help. [Answer] Another planet seems unlikely, given the time frame. Even Pluto's orbit is 'only' about 500 years, a far cry from 20.000. Also, it would not explain why the hostile period is only a thousand years. [Ice ages](https://en.wikipedia.org/wiki/Ice_age) might be a better solution, though ice ages on Earth have lasted from ca. 50,000 years up to a hundred million years. Nor are they very regular. Poul Anderson's 1974 novel [Fire Time](https://en.wikipedia.org/wiki/Fire_Time) has a planet that experiences a period of extreme heat every thousand years due to the planet's irregular orbit around three suns. This might be tweaked to suit your needs. Perhaps the best fit might be if is your planet and its sun is in a very [eccentric orbit](https://en.wikipedia.org/wiki/Orbital_eccentricity) around a far larger sun, or possibly a black hole with a [accretion disk](https://en.wikipedia.org/wiki/Accretion_disk) emitting hard radiation. A characteristic of eccentric orbits is that most of the time, the orbiting object is far away from the larger object it orbits and spends a relatively short time whizzing close past that object before returning to a farther distance. An example is the comet [Ikeya-Seki](https://en.wikipedia.org/wiki/Comet_Ikeya%E2%80%93Seki), which has an eccentricity very close to 1 (which is the limit for orbiting objects). Its aphelion (furthest distance from the sun) is roughly 200 times that of the Earth, but when it last came closest, it came within 450,000 km of the sun's surface - not much more than the distance between the Earth and the Moon. Its orbital period is roughly a million years. This is far more extreme than what you need, but shows that it is possible. Finally, since your planet is a fantasy planet, there might be a fantasy explanation. It may be that the dragons breed every 20,000 years and get a bit rowdy during that time. Or there may be a bit more exotic explanation like in the [Earthdawn](https://en.wikipedia.org/wiki/Earthdawn) role-playing game, which has a recurring Time of Horrors. [Answer] I am slightly skeptical that you could have a stable system involving a doomsday planet that comes close enough to cause tidal heating without seriously disrupting the orbit of both planets after the first pass. Its the sort of thing that might cause any moons of your inhabited world to leave for somewhere more gravitationally friendly. Now, I am no orbital mechanic, but I think that a more plausible means of periodic catastrophes are meteorite showers. One source might be gas giant planets in the outer solar system having an orbital resonance that periodically disrupts the local equivalent of the asteroid or Kuiper belt, flinging a bunch of comets and asteroids into the inner solar system some of which end up falling onto your unfortunate world. Big asteroid impacts are obviously Quite Bad in themselves, but they are also linked to major volcanic events too, if that's important to you. [Answer] ## Biological Infestation Have you read the [Pern](https://en.wikipedia.org/wiki/Pern) books by Anne McCaffrey? The series is science fiction, though much of it is indistinguishable from fantasy, as it's a colonial world that has regressed technologically and depends on fire breathing 'dragons'. One of the major environmental issues in the Pern books is an organism called Thread, which floats onto the planet every time a rogue planet, with a highly elliptical orbit, passes near Pern. The Thread organisms consume pretty much anything organic they touch. Obviously you wouldn't want to directly copy this, but it could be a good jump start on thinking about other ideas. [Answer] If you want to have a repeatable pattern occuring every few thousand years I would suggest a biological reason rather than geological/astronomical. This way you can explain that the cycle is a part of a wider pattern in the ecosystem which lets you imagine more complex situations than just "boom! everything is destroyed! start to grow legs again, you stupid fish!" ;) We are used to think that ecosystems are stable, but that's only because we have a very limited timeframe. Even though we know that there was a very different climate just twenty thousand years ago (and that now climate changes are even faster), our intuition tells us that summers and winters should be similar each year and nothing is really changing unless there is some kind of a catastrophic event. But that's only because our lifespan is 100 years tops. The ecosystem works on grander scale and doesn't need any meteorites or global volcano eruptions to go through different phases. It is also possible that there are intervals of short rapid changes followed by a long time of considerably more stable situation. I would start with the assumption that the most complex life on the planet is amphibian or that all species which resemble mammals and birds are capable of spending their whole lives on water if ground is too hostile. When the conditions on ground improve, those species are able to quickly colonize the new ecological niche. But since a few thousand years is not enough for evolution, all those species will be dependent on water: so no complex animals in steppes, deserts, mountain plateaus, etc. That part of the world is left for a very different ecosystem, one composed of plants and animals which are smaller, simpler, but because of that they can multiply and spread very quickly when they reach certain "critical mass". Think of it as a biological version of a nuclear bomb. We start with a very desolate place, a desert far from water. There are some species of plants and animals there, but they're rare and live in a fragile balance: plants grow, herbivores eat them, carnivores eat herbivores, less herbivores mean more place for plants to grow, but also carnivores starve, and this small cycle of small organisms (bugs? insects? miniature tentacle monsters from hell) repeats itself. But this is not really a balance. Every cycle the average population grows a little. And with bigger population, every cycle is a little bit more violent. At some point we reach the critical mass and everything goes boom - in the biological sense. The plants of this strange violent ecosystem spread rapidly around the globe. Herbivores follow, but eating not only the plants they know, but also one which survived in the waters and only recently started to colonize the shores. Carnivores follow, but hunting not only herbivores they know, but all the complex animal life which survived the last cataclysm living in the sea. The only way for the complex ecosystem to survive is to hide in the sea again: the miniature tentacle monsters (\) cannot be stopped. But when they finally eat everything in their way, they die of starvation. And since the cycle was so violent this time, only a very small number of the species form their ecosystem survive - somewhere far away from the shores, on the desert, starting a new small cycle within a bigger cycle which takes thousands of years. \) I think it's too easy to think of them as a swarm of insects. I'd invite you to imagine something different. [Answer] While I'm inclined to favor the orbit-involves-something-nasty answers (note that the nasty object could also be a fast-spinning neutron star, the jets can be powerful) you've got a far bigger problem here: After you have wiped out the land breeders the first time there will be no more land breeders. Your period between encounters is nowhere near enough for new land breeders to evolve. ]
[Question] [ This question is about an idea/decision I use in my conworld. There are also plenty of other questions on that world such as [this one on steam engines](https://worldbuilding.stackexchange.com/questions/57761/how-to-make-the-development-and-use-of-steam-engines-preferred-over-that-of-comb) or [that one on military forces](https://worldbuilding.stackexchange.com/questions/38921/can-a-super-governmental-military-body-like-this-work). The setting is that of a world with a technological level around the [Interwar Period](https://en.wikipedia.org/wiki/Interwar_period) and a societal level around that of the [Victorian Era](https://en.wikipedia.org/wiki/Victorian_era). Though answers to this question are encouraged to go further back to [Medieval times](https://en.wikipedia.org/wiki/Christian_views_on_alcohol#Middle_Ages) and farther. --- That said, this question is about the decision of a larger region or country granting the local clerical body the exclusive right of the production of alcohol & alcoholic beverage, as well as the right of granting brewing/distilling permits to third parties. The church does not control import/export of alcohol & alcoholic beverages, but they decide who they supply with their own products and who not. Thus they effectively control the supply of alcohol in the whole region/country and thus the festiveness of tens-of-thousands of people1. Q: Why would they be granted such an exclusive right/permission? I have thought about them in turn having to provide certain amenities or similar, e.g. hospitals, almshouses and orphanages. Certainly these services and their provision would have grown over time with the cultural connection of church and wellfare as well. But would that be a big enough burden to offset that huge boon of controlling a major commodity? 1Again, excluding imports from other regions/countries.. --- Addendum: The church itself is a rather huge [polytheistic](https://en.wikipedia.org/wiki/Polytheism) confluence of older simpler polytheistic and monotheistic religions of different areas and tribes. They started off as the spiritual part of herdsmen and nomads of the Green Wides. Due to the nature of the people of these areas, the original churchmen started creating fix settlements where the wandering groups would find shelter, could exchange wares and bury their dead without fearing bandit raids or similar. Over time the wandering groups would strife further north, west, south & east and thus get in touch with other groups and religions, which they understood to integrate into their own pantheon in order to mingle with these others.2 2Others that soon became part of their growing culture & society. --- Anotherdendum: As many seem to still automagically assume Church to refer to a monotheistic organization based on a set of two books that in turn are made up of dubiously sourced letters and other short texts - here's a definition: > > [Churches:] > > > * claim universality, include all members of the society within their ranks, and have a strong tendency to equate 'citizenship' with 'membership > * exercise religious monopoly and try to eliminate religious competition > very closely allied with the state and secular powers - frequently there is overlapping of responsibilities and much mutual reinforcement > * extensively organized as a hierarchical bureaucratic institution with a complex division of labor > * employ professional, full-time clergy who possess the appropriate credentials of education and formal ordination > * almost by definition gain new members through natural reproduction and the socialization of children into the ranks > * allow for diversity by creating different groups within the church (e.g., orders of nuns or monks) rather than through the formation of new religions > > > [Wikibooks: Introduction to Sociology; Johnstone, Ronald L. 1997. Religion in Society: A Sociology of Religion](https://en.wikibooks.org/wiki/Introduction_to_Sociology/Religion#Church_and_Ecclesia) [Answer] I live in Pennsylvania. Let me answer this from local experience. No, the church doesn't control alcohol here, but the state Liquor Control Board does. Your question has two parts: how a body gains control initially, and how it holds onto this power. (You didn't actually ask the second part, but it's relevant.) Governments sometimes prohibit or restrict material that they consider dangerous. In the US, alcohol was prohibited entirely for a time by constitutional amendment, which means a large number of people with political power decided the matter. Then later, a large number of people with political power said "never mind", but even though it was no longer prohibited, it remained regulated. Some drugs are similarly prohibited (e.g. narcotics) and others regulated (e.g. marijuana, in some jurisdictions). Other matters of personal consumption are also regulated (e.g. tobacco). In your world, your government needs to decide (and popularize the idea) that alcohol is dangerous in some way and needs to be regulated. It can then entrust this regulation to the church (who probably lobbied for regulation in the first place, either secretly or openly). Your church should be broadly seen as doing good work and being deserving of the trust. (The PA liquor control board didn't need to meet this requirement because it's an arm of the government, but an outside body would.) Once they have control, how do they retain it? Political scheming can work, but popular support works better. In PA a lot of this comes from labor unions (who staff the stores); in your world the church will need popular support, like being the dominant religion. Your church, like the LCB, will make sure that there is widespread education about the dangers of alcohol. It might facilitate groups like Mothers Against Drunk Riding (sounds like you might have horses rather than cars). The church will ensure that people's alcohol needs are being met, that people can buy (perhaps-limited) amounts for their festivities. So long as people see that drinking isn't getting out of hand, but they can still get wine for celebrations, they'll leave well-enough alone. [Answer] Consider the power that the Christian church held in medieval Europe. Now also consider the role which wine held in certain rituals (the blood of Christ). A powerful religious organization could argue that wanton alcohol consumption is blasphemous, and that they should have the power to regulate its consumption based on its importance in their rituals. Thus, the Church might become the only producer of alcohol, and/or the only entity allowed to charge other with producing this most holy of elixirs. Fidget with the details of how important alcohol is for them, and how often it's used, and you should have no problem explaining how they came about owning those exclusive rights. However, alcohol is rather simple to make. How will you stop disrespectful peasants from simply ignoring you? The Inquisition? Up to you to decide. [Answer] Moral As AndreiROM and kingledion conjectured, the church might have used its moral authority to control and thus limit alcohol consumption in the society. Many actual societies have developed similar institutions that were either enforced by the state (American prohibition) or religious organizations (eg. in the Islamic world). The cultural-evolutionary rationale for this is that wide-spread alcohol consume may limit a societies productivity, is correlated with crimes and social unrest and might even have destabilizing consequences for the regime in power. Spiritual Alcohol (and drugs, more generally) can be part of the religion's ritual. Either because they have consciousness-expanding effects or because they ease social interaction amongst people who barely know each other (one function of religions is to create a positive group identity and bring together / create a safe communication space). As a consequence, your church might have been historically linked to the production of alcohol and might have been granted an official monopoly by the state only to consolidate the factual monopoly that the church had already required. Rent-Seeking The role that rent-seeking will have played in any historical development will vary in degree but it is quite likely that rent-seeking will have played a (somewhat) decisive role in any explanation for why the church was to able acquire a monopoly on alcohol production. Important here are the facts that churches can be very powerful organizations, that their innocent appearances are ideal for lobbying and the expansion of their political and economic power. Economic With the technology level you have assumed (in fact, any technological level from the middle ages onwards would suffice) there is no sound economic reason as to why the monopolization of alcohol production is efficient for the society as a whole. The main reason here is that alcohol production involves very low fix costs (tinkering instead of R&D, low starting costs for a distillery) and thus, alcohol production is nowhere close to being a natural monopoly (in fact it is quite the opposite). Provision of health services and concerns as to the quality of alcohol Churches have often come to be (at least in some way) responsible for societal well-being. In the western world, for example, they have developed a close connection to the feeding of the poor and the provision of hospitals. If the church has come to develop a similar function within your society, they provide most of the health services and manage to successfully argue that any production of alcohol not controlled by them brings about severe quality issues (especially the case with privately-owned small scale distilleries), the state might have granted them the exclusive right to produce alcohol to avoid the issue as a whole. This, can be argued, to be only fair since the organization (here, the church) to provide all or most of the society's health services should also be given some control as to the most important health hazards. Food security during famines (credits to bdceaf) As production of alcohol uses up resources that could otherwise be used in the food production (most importantly, raw staple food but also capital and labor), it seems reasonable to limit the production of alcohol in times of famine. If the state would have wanted to guarantee basic food production for everyone, the church might a reliable partner to weigh off the gains from alcohol production (in their financial interest) and the risks of greater famines (not in their moral interest). [Answer] One reason may be simply a strict culture of enforcing intellectual property laws, or their equivalent - the church has the finest recipes and longest experience in brewing, and so their monasteries brew the best beer. It may actually be legal to brew your own - and maybe even to sell it - but not on any scale or at a price that brings you any reward. Let's face it, even if you can comply with the strict Purity Laws, your homebrew can hardly compete with the Trappist monastery down the road with 800 years of experience refining their closely guarded recipes. As supporting evidence for this idea, I present ... Belgium. [Answer] Perhaps the Church provides the alcohol for free to anyone who wants it (reducing the likelihood of home brewers). If this is not an option, then make the "wild yeasts" in the area produce bad flavors or heavy toxins if used. The Church has access to other yeasts that they use for their processing that provides the best beer. You could even tie alcohol (and any other mind influencing substances) to religious experiences. Maybe the only time your people drink is during ritual ceremonies and to become closer to the Gods. Your religious organization could even make it their dogma that spirits produced without the blessing of the Church are tainted and will lead a soul to damnation (adding in the fact that local wild yeasts are poisonous or foul tasting will reinforce this). [Answer] For many years the governemt may have supplied the church with the means to sustain itself by tax relief, and other social actions that allowed the church to survive. However, over time do to war, famines, and other social issues the state was either no long able or willing to do so but the common people still relied on the church for burial, spiral needs and the like. So, the stated had to do something, and decided to give control of production of alcohol to the church. So, that it may be able to parishly sustain itself, and still provide the relief that it need to for the community. [Answer] Alcohol needs to be blessed before consumption. Because wine is the blood of the Christ, non-blessed wine is the blood of the anti-Christ; or something like that. The church has no way of knowing whether an import is blessed or not and they are harder to enforce than the production, so the church may allow that. The funding of the church may rely on such monopolies if taxation is too hard, especially wandering people are hard, because you cannot go to their fields and see how much they are producing. It is always bad if there are some laws, taxes and regulations that cannot be enforced. This is because breaches hurt the authority. ]
[Question] [ 3-D printers, replicators, nanofabricators etc. are all technologies that, when pushed to their logical limit, seem to make the transport of finished goods obsolete when all you need to do to obtain any given item is simply supply your fabricator with the right raw materials. In a future with ideal fabricators, the only things that will ever be shipped between various human settlements (planets, colonies and space stations) are raw materials. Hydrogen, helium, and iron hauled from the asteroid belt and extracted from uninhabitable worlds will become the only commodities worth physically transporting across large distances. Is this vision of the future accurate? I want to write a story where space truckers and space pirates are an important element of the plot, but the utter absence of scarcity except in the form of raw materials seems like it would kill piracy and most forms of theft pretty effectively. At the same time I'm aiming to be pretty high on the sliding scale of hard sci-fi, so completely ignoring fabricator technology and pretending that we won't improve on 3-D printing at all in the next century and a half isn't really an option without completely discrediting the plausibility of my worldbuilding. Is there any way around this? Are any of my assumptions incorrect? [Answer] I think there will always be a need for long distance goods shipping, it's quite likely that large factories will still exist loooong into the future for the main reason that it will always be much faster and far cheaper to make things in bulk (how do you think the speed of a 3D printer compares with an injection molding machine when making a lego brick?). Another reason is that people can walk into a store a buy a ready made product there and then on impulse because all the hard work and waiting was done by someone else, whereas a 3D printer/nano-fab will have some arbitrary waiting time involved before your goods are ready. For example, it currently takes around 3 months and a mind boggling number of processing stages to make a single wafer of the latest and greatest computer chips, but because a large fab can easily churn out a finished wafer EVERY 10 SECONDS, odds are they will have one ready when you want it. Many of the industrial processes we rely on in the modern world are quite slow and time consuming, but because they are performed on an industrial scale (pun intended) and run 24/7, they are cheap and give the illusion of being ready when you want it thanks to the miracle of warehouse stock. The only way some kind of household nano-fab could compete with this would be either A) If the owner is willing wait months for the nano-fab to make their product or B) if the nano-fab can somehow artificially speed up the chemical reactions involved. So even in our interplanetary future, there will be tonnes and tonnes of long distance shipping for all kinds of things so that people will be able to just walk into stores and just grab stuff off the shelves on a whim whenever they want. Another reason might simply be that some companies might not release the designs for their products, I mean, Samsung might have the capability to make an iphone 6, but unless Apple shares the plans it's not going to happen. Giving people the power to make your product themselves means you effectively lose control over the designs and all your IP, I can't see big companies effective open-sourcing their entire manufacturing chain any time soon. But don't let all this discourage you from writing a good story, who knows, maybe nano-fabs really will be time and cost competitive in the far future, it's hard to say for sure. After all, as physicist Niels Bohr once said "it's hard to make predictions, especially about the future." [Answer] Is this vision of the future accurate? No, it is not, because it is missing one critical element of that story. The critical part is the distribution of the technologies. If they are distributed this or another way, you even do not need nanofabrication for that, good old automation is enough. But if not, distribution of goods may have a place, but it will be under heavy pressure for hardware hack, reverse-engineering of hardware will be a thing. In general, without implementing some kind of as of yet unknown type of engines, it is not viable to transport goods at space distances, with ships which use reactive propulsion. But such a distribution may have a place at initial stages. As for the problem with pirates, let them attack information deposits - labs, space habitats, ships, which may carry such information. Humans are still a valuable commodity - especially high ranked specialists, or just specialists for pirate colonies, as they probably do not have the intent to keep education etc. For sci-fi with pirates it is a possible plot. There was a relevant [question](https://worldbuilding.stackexchange.com/q/60125/20315) about interplanetary trading, and I wrote there a bit more detailed about technology independence. In short it is really more efficient to have local production, considering the energies involved in transporting goods. Still, there is a place for transporting exclusive goods. For example art and other pricey things, which are not the result of mass-production. [Answer] 3-d printing is not nano-fabricators. There are many things 3-d printing will be able to in the future, but many things that it won't. 3-d printing as we currently envision it would work well for metals and plastics, but there are lots of things that aren't metal or plastic. I'm sure there is no way to 3-d print complex organics, so printing, say, silk or fine wool for a suit is out. I don't know if 3-d printing can make carbon fiber. You can't 3-d print drugs, and you can't 3-d print some prestige goods like chocolate or wine. Also, you can't 3-d print water, which might be very valuable in a lot of places. I think the solution is to say yes 3-d printing, no nano-fabrication. We don't really have any evidence that nano-fabricators will be a real thing in the future, so you can probably be good with hard scifi and 3-d printers and space truckers hauling luxury goods and fine clothing. After all, thats what the Dutch spent years hauling around Africa in the 1600s. No one needed pepper and porcelain, they just wanted it. [Answer] In a future like that there are 2 types of material goods that I think will NOT be replaced by replicator goods: 1. Works of art: Even if no expert can distinguish the original from the replica there still will be a market for real originals and the people with enough wealth willing to pay for it as a status symbol. 2. Same thing goes for "real food" in stead of replicator food. There will always be people that (claim they) can tell the difference and the ones that must have "the real thing" as a status symbol. (Or maybe for medical reasons, if the replication process leaves some sort of residue to which some people are allergic.) Besides that: Space piracy doesn't have to focus on goods alone. There could be a huge black-market for stolen space-ships. Kidnapping people for ransom or to use as slaves comes to mind too. [Answer] Well, for once nanotechnology could be forbidden, even if only on some planets, either for [safety reason](https://worldbuilding.stackexchange.com/a/18729/30093) or because of [experience](https://worldbuilding.stackexchange.com/a/15002/30093). On the other hand, even today hand-made quality products are valuable and I don't expect this trend to die out, I rather expect it to grow stronger. "You lived twenty years with automatically produced stuff, but I have this wooden totem crafted by a child on Afrycan III after it lost its parents to erratic nanobots. It was so expensive the child can affort a house on Afrycan II now and that's why I'm the better person." Pirates would get a lot of crap, but very emotional, expensive crap. [Answer] I certainly envision shipping of elements, but that would typically come from small bodies (moons, asteroids, comets) not off of other planets. But that is shipping of bulk material throughout the solar system. I see a need for shorter range distribution. If industrial or specialized nanofabs are capable of things that the household version is not, or if nanotech must be quaranteened in a space-based platform, then you will have possibly planetwide distribution, but no further than that: the top of the production chain would be located near each inhabited planet. [Answer] 3d printers have one of my favorite little weaknesses. I love getting to abuse it in stories. 3d printers can only produce "quiescent" objects (that is to say, objects that hold still while printing). Most of the time this weakness is unimportant. So many things that you want to produce are indeed quiescent. If you want to print a gear or a brick or a scaffold for repairing a broken arm, the object naturally doesn't want to change very much, so it's easy to print. If you print something more fancy, you may have to add "support structures" to hold up your product during production. [![Propeller with support structures for printing](https://i.stack.imgur.com/VJUMl.jpg)](https://i.stack.imgur.com/VJUMl.jpg) However, as you go further down that road, 3d printing runs into issues. A lot of organics, for example, are not actually stable if constructed from one side to the other. They are only stable when produced the "right way," with protien folding. Another example might be trying to forge a Matisse with nano-scale 3d printing. It turns out that properly evaporating linseed oil is not an easy task -- and it is a very flammable task! It'd be virtually impossible to match the chemistry of a true painting. We've recently "3d printed" heart valves, but that's really only part of the story. Heart valves wont grow properly if you just 3d print the stem cells and go. What we actually did was 3d print them into a scaffold, and then used a circulatory pump to emulate the forces which shape a heart valve into its natural shape. This sort of hybrid approach would certainly be popular, but the mere access to 3d printing doesn't free you from importing the right stuff. [Answer] Lets assume a society with powerful general purpose nanobot tech and solar system wide space infrastructure. These nanobots could construct almost anything from a plan and abundant local materials. This includes people and so, if the nanobots are reliable and can record and recreate in sufficiant detail then you have teleportation. This atomic control over the human body need not be used to copy. Almost any disease could be completely prevented or cured. Humans might use such technology to augment themselves as they see fit. Minor changes that allow humans to thrive in 0g without bone loss are followed by more radical changes. Soon you have photosynthetic humans, humans with nanotube reinforced skin that can survive empty space unprotected, and cognitive enhancement. (other body parts may also be enhanced) At what point these beings cease to be human is left to the author. Nanotech allows products to be designed atom by atom to have the exact atomic structure to fulfill whatever task it was designed for. As almost perfect recycling will be trivial the space habitats will not need large amounts of new resources. Everything required can be produced within the same small space station while providing a high standard of living. The energy required can easily be collected via solar panels and beamed to the outer solar system via microwaves. A couple of square meters of bin liner like solar panels (at earth distance from the sun) could provide enough power to keep a human alive and comfortable. In short you will have a complete absence of scarcity and hardship and no one wants to take the risk and discomfort of being a pirate. This largely holds true even in todays world. I end with some quotes about a nanotech assembled rocket engine. <http://e-drexler.com/d/06/00/EOC/EOC_Chapter_4.html> Where great strength is needed, the assemblers set to work constructing rods of interlocked fibers of carbon, in its diamond form. From these, they build a lattice tailored to stand up to the expected pattern of stress. Where resistance to heat and corrosion is essential (as on many surfaces), they build similar structures of aluminum oxide, in its sapphire form. In places where stress will be low, the assemblers save mass by leaving wider spaces in the lattice. In places where stress will be high, the assemblers reinforce the structure until the remaining passages are barely wide enough for the assemblers to move. Finally, the vat drains, a spray rinses the engine, the lid lifts, and the finished engine is hoisted out to dry. Its creation has required less than a day and almost no human attention. Rather than being a massive piece of welded and bolted metal, it is a seamless thing, gemlike. Its empty internal cells, patterned in arrays about a wavelength of light apart, have a side effect: like the pits on a laser disk they diffract light, producing a varied iridescence like that of a fire opal. These empty spaces lighten a structure already made from some of the lightest, strongest materials known. Compared to a modern metal engine, this advanced engine has over 90 percent less mass. Tap it, and it rings like a bell of surprisingly high pitch for its size. Mounted in a spacecraft of similar construction, it flies from a runway to space and back again with ease. It stands long, hard use because its strong materials have let designers include large safety margins. Because assemblers have let designers pattern its structure to yield before breaking (blunting cracks and halting their spread), the engine is not only strong but tough. For all its excellence, this engine is fundamentally quite conventional. It has merely replaced dense metal with carefully tailored structures of light, tightly bonded atoms. The final product contains no nanomachinery. [Answer] Piracy isn't about hitting the jackpot everytime. It is a lot of hard work, with little to no luck until finally you hit paydirt. And what do past and present thiefs get the most money and thrills from? Artwork, Antiques, Family Heirlooms, Cultural treasures, Status symbols, the thrill of beating the unbeatable etc. Alot of items in today's world, and I assume the future, isn't expensive because of the cost to make it (although that can play a part) but rather the history or origin of the item. You can't manufacture the past history in a 3D printer, no matter how good your nanotechnology is! Having a conveniently 3D printed wooden table or decorated vase doesn't quite make a Resolute Desk or Chinese vase of the Ming Dynasty. Your cargo ships will be filled to the brim with expensive, hard to find, one of a kind items, being transported securely from one world to another at the whim of some super rich tycoon or political despot. Not every shipment will be so valuable. Just as today, not every shipment is so valuable. Mundane core materials still have to get transported. If your space pirates can get their hands on the transport schedules, they will have a field day. Rest of the time? They will be scrapping the barrel, looking for that one big score and threatening the captain with mutiny. [Answer] What would be worth shipping between planets would depend on exactly how capable nanomanufacturing is and exactly how cheap interplanetary transport is in your world. Things that would work under most assumptions: * Rare elements. Even the most advanced nanotech manufacturing or 3D printing would still require the right elements in the raw materials, and a lot of high-tech devices use unusual elements (hafnium in plasma torch electrodes, neodymium in really strong permanent magnets, etc.) In addition, elements common on Earth might be very rare on some worlds (such as hydrogen on the Moon - there is some ice in the polar craters, but it would be tiny compared to even Mars's ice supply, much less Earth's oceans or the gas giants' atmospheres). * Things that require extreme temperatures/energies to make. Plausible nanotech will likely have severe trouble with high temperatures and energies - nanometer scale is the scale of proteins, tens of nanometers is the scale of the smaller viruses, so manufacturing devices on this scale will probably be acting more like chemical synthesis than classic "factory" industrial manufacturing. That probably means fairly strict temperature dependence, and something as small and complex as a nano-manufacturer would probably be easily destroyed by the temperatures needed to produce e.g. diamond and other special forms of carbon. * As others have pointed out, works of art, antiques, and other things valued for "intangible" reasons would likely retain their value regardless of manufacturing technologies. Other things that might be worth it given certain assumptions: -Complex biological products. As mentioned by others, these might be tricky to manufacture. They might be viable exports from Earth. This could overlap with "things valued for intangible reasons" - even if there's synthetic coffee/chocolate/etc. that tastes the same, rich people on Mars or asteroids might likely still value "real tree-grown" coffee/chocolate/etc. -Things whose manufacture is artificially restricted. This would only be possible given certain assumptions about how the manufacturing technology works, but under some assumptions, some things might only be possible to "higher grades" of nano-manufacturing, which some worlds might lack - maybe because of some mercantilist-style policy or security concerns about manufacturing some weapons. ]
[Question] [ I saw some games or stories where space mines were used. My question is: would it really work ? I think the chance of hitting a mine is really really low in space. Where would you place a mine in space to be effective and how should the mines work, to be efficent ? [Answer] Mines could work if we stretch the [definition](https://en.wikipedia.org/wiki/Naval_mine) of a mine. The problem with space is... 1. it is big 2. really big 3. you just won't believe how vastly, hugely, mindbogglingly big it is 4. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space. Listen... So our mines can't be stationary as they'll hardly ever be in the right place at the right time. They also need to have a really big impact and they need to be invisible. All of which, not ideal... So first things first, you need to pick a place you want to defend... forget anything bigger than an asteroid as the area of space you need to protect from gets ridiculous. Ideally, you need to limit your enemies movements, so get a load of mass and stick it in close orbit to your protected rock, not ideal but it does cut off some guys coming in. Another limiting factor could be putting your rock in a gravity well of a bigger rock, making it more costly to reach you. So now we have our place to protect, now we can look at the mines. The mines need to be active and seek out their prey, some quick thoughts on this * Use compressed gas for maneuvering instead of rockets to reduce heat signatures * Use RADAR/LIDAR passive jammers (mirrors, sharp edges) to avoid detection * Use passive scanners only, the mines don't emit anything by themselves * Use cluster bomblets to deliver payload, instead of one single mine, have a 1,000,000 smaller jammed in together, this is to overcome any ship to ship guns * have the bomblets release if the mine is fired upon, if someone fires on it, the mine doesn't go off, but disintegrates into a cloud of bombs * have the bomblets use a static charge to dissipate themselves without expending energy and also to attract them to your enemies ships But really, with all these put in place, mines are still not ideal unless someone is coming to enslave you instead of wipe you out. If I was fighting a war in space, I'd just keep throwing rocks at your base until one of them hit. An alternative use of mines like this would be to deploy them around your ship if pirates come a-knocking - you can use them to drive ships off and make a safe zone for you hightail it out of there. Edit - why not use a Dyson Sphere In comment discussions, we have postulated the use of a Dyson sphere - directing all that power inwards towards a fleet would have a significant impact the same as a minefield and it solves the issue of trying to cover everywhere at once. The power level/damage would be massive but a co-opted civilian system would not be as accurate (otherwise bye bye fleet entirely) [Answer] Actually i think the viability of space mines depends on the technology available. First, a mine is comparatively tiny. I don't think they'd be bigger than let's say 5-10 meters diameter, otherwise you can't transport any significant amount of them. So how can a tiny spaceship of let's say 1km hit an even tinier mine in the vastness of space? It can't. The chances that a ship will pass close by, let alone HIT the mine are so tiny, that the costs of making a minefield would be so high that they wouldn't be effective at all. The secret is to make cheap mines that destroy expensive ships. Otherwise you could build expensive ships to destroy expensive ships. So our mines need to destroy or damage the ships when they get "relatively" close. In order for them to do that, they need passive sensors to know when a ship is nearby. Ladar or Radar ain't gonna do it, because they can be detected, giving away the minefield loooong before the ship is there. Maybe magnetic or gravitational (handwaving required) sensors could do the trick. So once your mines knows there is a ship coming, it needs to "detonate" to destroy the ship. It could use several methods for that: * Ignite its own miniature rocket drive, homing in on the ship and detonating itself. Spoiler: this is not only lackluster, but probably won't work. Point defense lasers, dodging and obviously losing the stealth advantage waaay before detonating will underMINE this approach. * Spray a gigantic cloud of metal shreds (or sand) right in front of where the spaceship will pass by. Still, given the giant size of space, i don't think this will be sure enough. Also, depending on how the micro meteroid problem is solved in your universe, the ships might just take the debris with their shield/armor/deflection field and travel on. * How about a single, one-use, very powerful chemical laser? Or Maybe fueled by a miniature thermonuclear reaction? The mine determines if the ship will be in "range" uses micro-thrusters to aim it's laser, and then BOOM. They could host quite powerful one-shot lasers, taking the unsuspecting victim by surprise. Bonus points: because you use a laser, the shot cannot be dodged or defended against, because the ship can't know it's coming. This approach would increase the "detonation radius" of our mine to laser range, which might still not be "long" but definately so much longer than a "classic bomb", that minefields might become valuable again. * Forgot the most obvious one: have the mine shoot missiles at it's victim. Maybe the mines can communicate with each other stealthily and "wait" for the target to be close enough to several mines, so they can flood it's defenses with a cluster of missiles. [Answer] A mine in space will be something like a [CAPTOR sea mine](https://en.wikipedia.org/wiki/Mark_60_CAPTOR). Since space is vast, and you will have limited resources, the reason for having a "minefield" will be to deny access to something valuable, which is most likely a planet. To do so, you will need to have your mines in orbit around the planet to make it difficult for enemy spacecraft to orbit your planet. This can be done in many different ways; the least sophisticated (and probably most expensive in terms of mass and lift) would be to fill LEO with all kinds of space junk. Particles of sand or ball bearings whining around the Earth at 7 km/sec would have a huge amount of kinetic energy relative to their size (An object impacting at 3 km/sec delivers kinetic energy equal to its mass in TNT. This is often known colloquially as "1 Rick" of energy). An incoming ship wold be effectively pelted with hand grenades and have sensors, radiators and other "soft" equipment rapidly stripped away. The disadvantage of this minefield is it is going to be difficult and expensive to clear it, both for the attacker, and equally for you, should you need to launch your own spacecraft. If the "field" is in polar orbit, you effectively block both incoming and outgoing flight from the entire planet. Captor type mines get around this problem by orbiting in defined paths, but having sensors and the ability to launch offensive weaponry at the target (A CAPTOR mine houses a torpedo). A simple form of this would be mines carrying missiles to launch at the target when it comes into range. Since multiple mines could be in range at a given time, the enemy ship suddenly has to deal with a saturation attack. More advanced forms of this would exchange the missile bus for a nuclear warhead. Following the Atomic Rockets "[Conventional Weapons](http://www.projectrho.com/public_html/rocket/spacegunconvent.php)" site, nuclear explosives can drive high velocity kinetic or energy attacks against spacecraft. This not only puts the craft at risk from long distances, but the extreme velocity of the projectiles ensures there is no left over space junk near your planet (although the objects will continue to move through space until something stops them in the future). Nuclear explosions can drive "shotgun" pellets at 100 km/sec Nuclear shaped charges which can drive slugs of liquid metal at up to 3% of the speed of light Casaba Howitzers which are specialized shaped charges which emit a star hot spindle of plasma at 10% of the speed of light (enough speed and energy to be comparable to very powerful laser weapons at hundreds to thousands of kilometres away without a heavy and expensive laser generator. Conceptually, nuclear explosions can also drive X ray lasers, providing huge energy dumps on a target at the speed of light. Weapons like this extend the reach of a "mine" to distances from hundreds of kilometres to up to a light second (after that, light lag means the enemy spaceship has ample opportunity to evade incoming strikes). Remember, mines are automated systems, so the enemy could spoof them or discover a means of disabling them. Alternatively, he could choose to sacrifice some ships (perhaps empty hulks) to discharge enough mines to create a clear space to operate. As mines become more sophisticated to deal with this, their advantage of being numerous and inexpensive declines (although they will still be far cheaper than spaceships with comparable weapons load outs). [Answer] Well, they may. Explosions in space [are nothing like Earth explosions](https://www.quora.com/What-would-explosions-in-space-look-like). As this link points out, no flames whatsoever - it would be only the mine's debris going in every direction, in a straight line. If you're a tricky one, radiation too. So how could you injure a spaceship? --- In our current world, [fragmentation grenades](https://en.wikipedia.org/wiki/Grenade#Fragmentation) already use this kind of technique to injure enemies. In space, you could have mine filled up with injuring parts (either cutting through or hurting the shell like a ram). Your blowing power, however, needs to be massive (depending on the ship which will detonate the bomb). The main problem with mines is that it is really hard, in a realistic manner, to immobilize them in space. Even the slightest force will result in it going through space (at a really slow pace, maybe, but still). You may anchor them, but they'll be more visible, and the anchor itself may cause damage to the structure it is bound to. --- With this kind of information, you can even make direction-oriented mines, with the center of your explosion not centered, and the debris in a certain position (I'm having a rough time explaining this but I'm sure you are understanding). Be the problem of the place ... Usually, when we are talking about space travel, we are making the assumption that there are space routes. Star Wars even defines this as [hyperlanes](http://starwars.wikia.com/wiki/Hyperlane) for hyperspace travelling, but no man would be fool enough to travel in space without any guidelines. If we're in space, we set up safe roads to travel there. --- So let's summarize: * PLACES : Space roads, used by most space ships (no hyperspace tho). * EXPLOSION: Fragments scattering in every direction / a chosen direction. * DETECTION: Let to the user (laser, distance, movement ...) I guess it could work, in a world where space travel exists. The only difficult thing would be to keep them stationary, but really stationary, I think. [Answer] ## It doesn't seem likely, not without some handwavium Mines generate a force when touched, this force, on Earth is represented as a shockwave that tears apart the offending ship, it's why, here on Earth countries are obliged by international law to declare when they're laying minefields so that shipping lanes and commercial vehicles can avoid the area, but these declarations do not have to be specific ([See Here](https://en.wikipedia.org/wiki/Naval_mine)) In Space, however, there's very little, if any material to use to generate such a shockwave, (Note: Space, despite its name is not empty) this means that, in order for a mine to be effective, you'd need your opponents to be really close to the mine. Bearing in mind that any space-faring civilization is likely to have Faster-Than-Light travel to get anywhere in a remotely relevant time frame when compared to the average lifespan of a Human, this means that a mine probably won't have a chance of hitting said ship and explode... into empty space Another thing is that, in Space, you're not bound by the laws of friction and aerodynamics, meaning the prevailing force in play is Gravity. Any body of mass has its own gravity; the more massive an object, the larger its gravitational influence. 99.9% of this influence in our Solar System is generated by our Sun (Sol), so leaving a mine floating without any kind of thrust is just going to get said mine pulled into the Sun, this means that the mine will need to be constantly changing its location to compensate. ([Newton's law of gravitation](https://en.wikipedia.org/wiki/Orbit#Newton.27s_law_of_gravitation_and_laws_of_motion_for_two-body_problems)) [Answer] If by mine you mean a fixed or semi fixed single use automated defense system, they could work. If you mean a big bag of explosives that goes BOOM when something triggers the detonator, not so much. And even today not all mines fall into the latter category. For example the US Navy employs or employed the so-called CAPTOR mine, which operates by detecting a ship or submarine within its vicinity and then launches a small homing torpedo (of the same type typically used by ASW helicopters) at that target. A space mine could work along the same lines, launching a guided missile at the detected ship. Another variety could have a high power X-ray laser fed by a nuclear explosive. When a target is detected, the mine orients on the target, the explosive detonates, and a high energy pulse of X-rays is fired at the target as a result, destroying the mine in the process. Again, something similar has been done on earth, most famously the shooting aparatus installed by the East German government on the fences surrounding their country to shoot those attempting to flee, which would detect breaking wires in the fence and shoot towards the likely point of breach. These were single shot (or salvo) and could be reset and reloaded of course. [Answer] An alternative, low-tech approach would be using the mines not as a way to destroy enemy ships but to denial them the access or at least slow them (I read somewhere that this is the actual strategic usage of land mines; any mine that you deploy may be deactivated by the enemy, but it forces the enemy to slow down so your patrols can detect/fight it). Imagine an incoming enemy fleet homing on your homeworld and going at 0.75c. Even if your network of scout satellites detected them at 1 light hour of distance, you will get the warning only 15 minutes before the enemy fleet arrives. Now lay in the enemy path a bunch of rocks in stationary orbits. From you enemy fleet POV, that is a bunch of rocks coming towards them at 0.75c. If the rocks are detectable 1-light minute away, it means that the ships only have 15 seconds to try to alter course before collision (and that is without counting the time contraction in the fast moving ship!). That would be a more than enough reason for enemy fleets to move at slower speeds, giving your defenses more time to prepare for the coming battle. And alternative use is to force the enemy ships to take active measures against your mines, which makes them visible. Imagine that your scout satellites work by detecting energy emission, and a fleet can be effectively hidden by just shutting down engines/weapon/comm/detection systems; that fleet could just set a path your world outside your network range and "drift" slowly towards their unsuspecting victims. It may involve some risks if they cross the eventual astray asteroid but their odds are good enough. Put in the middle the same bunch of rocks and suddenly they need to start activating detection systems to detect the "mines", weapons to destroy them or shields to protect the ship or engines to avoid them, all of which will make them detectable by your scouts. This plan is simpler but requires that you put a considerable amount of "mines" in orbit to ensure that they work as deterrent; that will depend of what is at stake and the power and number of enemy weapons (for example, if the enemy is fighting for its survival and has a planet-eraser bomb, they may send all of their ships anyway and hope that at least one of them survives and wins the war for them). [Answer] In orbit, you have [Kessler syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome) - doesn't even require explosives. Outside orbit, it relies on having commonly used routes. If you can find a way to accomplish this (wormholes or warp gates) then it's reasonable. Otherwise, the area you need to cover becomes quite large, so you'd need very advanced mine technology for it to be viable. The mines themselves are only that by analogy. Land mines cover a 2D surface, so it's possible for them to intersect every path, thus they can just wait for someone to step on them. With space mines this will never work, you need the mines to have their own propulsion. They must also have their own sensors to detect enemy ships and target them, so we're talking "smart mines", more like automated guided missiles. This also gets around the issue of asteroids plowing through your minefield. Every mine will have a "sphere of attack" which is a large volume (not necessarily shaped like a sphere or even a single bounded volume), bounded by its delta-V vs. the target, and where the target is coming from/how fast. So SOA depends on the target, and may not even necessarily center on the mine. When the mine detects a target intersecting this, it fires thrusters and attempts to intercept. The effect of this is that certain trajectories are precluded because if you follow them, you are guaranteed to have several missiles on you. The weird part is that while land mines define these trajectories based purely on space, with space mines you would also consider velocity (of both target and minefield - moving minefields are possible in absence of friction), delta-V and thrust of the mine/target. A military that uses mines would have access to competent statistical expertise and artificial intelligence (not the terminator kind, but the cruise missile kind) to set them right, although that's probably a given for space navies. They would decide on what enemy movements by what kinds of vessels are most dangerous, and lay the mines accordingly to get the most bang for their buck. Nimbler ships will tend to escape, and other ships if they are going too slow or too fast or in a different direction will also be unaffected. Since the mine is a fair bit of technology, you have some nuances that can serve as plot points: * Mines can have friend or foe detection, but of course old minefields with obsolete codes become a concern * Mines can self-destruct, either by timer (set according to how long HQ expects the minefield to be needed) or by remote control * Remote control to deactivate mines, collect them and set somewhere else * Mines can be hacked to wreak additional havoc * Anti-mine decoy ships and the arms race between these and mines * Mobile minefields that fly through their useful corridor, and allowed to then drift off into unknown parts of space (and minefields that arrive from who knows where) Although I would expect to find mines primarily in some sort of useful orbit. Orbiting/deorbiting is the bottleneck of space travel, and most useful space travel does it often enough. Just denying commonly used orbits to your enemy could go a long way. Failing that, mass foci in deep space (such as space stations used for resupply) would be a good place. Trying to just carpet mine all of space seems as pointless as trying to mine an open field or ocean on Earth. [Answer] Think something along the lines of the [Very Dangerous Array](http://schlockmercenary.wikia.com/wiki/Very_Dangerous_Array) (VDA) used in [Schlock Mercenary](http://www.schlockmercenary.com/). Basically, you have a massive number of missiles/torpedoes, each fitted with a basic AI and a suite of sensors. All the torpedoes are deployed, spread out, over the area you want protected. The VDA was originally meant as a giant telescope, but it had the wonderful side effect of having all the projectiles already deployed, waiting to be sent at targets at any instant. Thus the name. The more torpedoes you have deployed, the more area you can deny, and the better resolution your explosive telescope array can provide. Of course, since we're using torpedoes, you could argue that they're not really mines. But when they're deployed but not actively trying to kill a target, they're basically motionless and lying it wait just like naval mines. So to answer your question, space mines would work if they're self-propelled, smart-ish, and deployed in massive quantities. They can also double as a telescope array if you're smart about it. [Answer] There's these interconnected issues: Range of the mine and distance to target. It's hard to estimate how far away a spaceship needs to be from an explosion to be safe. However, the [project Orion](https://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29) proposed to propulse rockets by detonating small nukes (0,15kt) just tens or hundreds meters away from a (specifically designed) pusher plate. So my guess is that a ship is safe if it's a a km or a few away from the mine. Along with project Orion came the idea for a directional nuke, where a bit less than half of the blast is concentrated into a narrow arc of maybe 30°, a bit less than half goes out in a semisphere the other way (conversation of momentum). If you can aim that narrow arc at your hostile ship, it would need to be farther off but not by orders of magnitude. In conclusion, my guesstimate is our small mine needs to be closer than 1 km to do real damage. How about bigger bombs? Let's take the Tsar, at 50MT or roughly 330.000 x the yield of our small Orion nuke. Whatever effect our nuke has it will likely drop with the square of the distance so we need to be ~580 times as far to be as safe, compared to the small nuke. So in case my guesstimate holds, maybe 600 km from the Tsar. Take this all with a huge load of salt however: Shockwaves don't really work in space so we would probably look for a bomb that produces a huge load of hard radiation which I think the Tsar is not. Now space is big, so keeping a 600km berth should be easy, right? Well there is this [idea of the interplanetary transport network](https://en.wikipedia.org/wiki/Interplanetary_Transport_Network), a set of routes that are very efficient (if slow) for rockets. Supposedly. One trick is to fly through [lagrange points](https://en.wikipedia.org/wiki/Lagrangian_point) like the one between moon and earth, which are also stable positions (or rather orbits) to put your mine. But even so, flying around the lagrange point by a few thousand km is probably not a huge deal for any rocket and many missions don't use these low energy transfers. OTOH, a mine on a lagrange point would be an easy target for a far cheaper weapon to clear, and would be comparatively easy to find. It's hard for me to imagine mines being effective in space. [Answer] # No. Taking away all the issues with how explosions have limited utility in space, and the fact that space is so huge that you can't really hit anything with anything without trying super hard, the fundamental concept of a mine is simply put incompatible with space. A mine derives its danger from the fact that it's hidden, but in space [it's not really possible to hide](http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth). In order to sense nearby targets, a mine would have to operate at temperatures dozens to hundreds of times hotter than the background, and that energy has to go somewhere, leaving a telltale signature that can be spotted from approximately all the way away. [Answer] Depends on what you mean by mine, and how willing you are to play with orbits If you mean "Conventional explosive that someone runs into" then no, for the reasons you laid out in the question. However, if you mean "Autonomous weapon system that sits in a region until activated" then you're in luck. Imagine a bunch of tiny [Cubesats](https://en.wikipedia.org/wiki/CubeSat) placed in varying orbits around a planet - Retrograde, polar, 60 degree incline, the only important thing is that they're all in different orbits. They sit and look pretty until they're activated by a ship nearing the planet they're guarding. As it approaches they examine the ship to see if it's going to enter into their orbital region, and if yes the mine with the highest intercept velocity is told to alter its course to intercept. As an example, if I had a swarm like this around earth and I wanted to get rid of the ISS, I'd pick a 'mine' orbiting retrograde to the station at a roughly 60 degree inclination. The sat would then line up its trajectory, and smash into the ISS at a blistering 34,000 Miles per hour. Bonus points for packing the sat with a self-destruct charge to turn it into a shrapnel shotgun. Best part is you could cheaply place these 'minefields' around any planet your foe wants to use as a gravitational slingshot, and use their own speed against them. The high approach velocity means that they'll have less time to detect a soccer-ball sized mine, and better yet that the impact velocity is going to be obscene. [Answer] 1. Think of space mines as missiles which are already close to the target. 2. Invaders want to avoid missiles, including your mines, so they just stay away. 3. You want to avoid your own mines, so you need safe zones in the minefield. 4. You don't want safe zones for the enemy, so there are forts or patrols in the safe zones. So, space mines aren't primarily meant to knock out invaders. They are meant to funnel invaders into the safe zones where they can be shot by active systems. If your defense makes the bad guys go away without attacking, you win. If it makes them come at your strong points head-on, probably you win. I probably got most or all of this from David Weber's Honorverse books, so go read. [Answer] Yes, but.. So mines don't even work that well at sea unless you have a way to constrict them to a specific area. Meaning you can't mine the entire Atlantic ocean, or even the Gulf of Mexico, but you could mine the port of Tampa, as part of a blockade. The same is true in space, but with a added "dimension". You could mine an orbit, or exit from a "gate". Maybe a known path or trajectory. For example, if every ship going to Alpha Centuri had to slingshot withing 1 mile of Jupiter's atmosphere, Hey you could mine that. Or perhaps the asteroid belt has 1 asteroid that is awesoium on it. You could mine that asteroid's area, but you could have a hard time mining the entire belt. This is true for naval warfare too. Mines are not effective in the open. There better in tight controlled spaces. [Answer] Mines work on the concept of denial. They make it dangerous to your opponent to enter a certain area and significantly increase their risk if they do not alter their behaviour. Mines in space could work where you have a clearly defined chokepoint. * Well defined shipping lanes * Translation points (think wormhole exits, jump points, warp gates, if such technology exists in your world) * Approaches to anchor points If you can't find a chokepoint then it's unlikely you'll have enough mines in the vastness of space to saturate an area large enough to matter. [Answer] If you're using sub-light, takes a lot of emery to change direction speed up/slow down then yes, but only because there is a pre-determined place that you are going to and you are going to and i have plenty of time to calculate where you are going, how soon you'll get there. and lay them all down. Even if it doesn't hit the intended target, the targets will waste valuable energy slowing down. Mines also provide a shell that means that a ship has to keep a more distant orbit, but that is more of just a small nuisance than an actual issue. [Answer] I'd refer you the Deep Space 9 Episode "Call to Arms", in which such mines are being laid. In the episode, the mines are shown as being roughly a metre across, and being laid perhaps 100 metres apart in a grid pattern. (They were to cover the entrance to a wormhole, preventing an enemy fleet travelling through it.) These aspects of the mines is what allowed them to work: 1. Each mine could cloak. 2. Each mine could self-replicate (so that the enemy couldn't "punch a hole" by sacrificing ships) 3. Each mine used sensors to detect a nearby ship, and had propulsion so it could attach itself to the ship. This is similar to some sea mines in WWII which used magnets to attract themselves to passing ships. 4. A ship would only attract 20-30 mines (since each mine was so small), so that there were enough to destroy it, but not enough to deplete the field. Apart from dealing with explosive yield and ship speed, this is plausible. [Answer] Don't take a classical sea mine and deploy it in space. This would be like trying to use a land mine at sea. As pointed out by various responses, explosions would consist of accelerated debris and gas only. It would be logical to implement homing mines, that work with a proximity detector of some kind. This kind of homing space mines are seen in the anime Legend of the Galactic heroes. There they are deployed in huge fields across anticipated enemy routes. Because of the fact, that you won't move slow in space (it is really really really big), anchored mines would pose an even greater thread. It would be possible to deploy massive but small spheres of a high density material and link them with chains to create a net. Because the objects that can be detected by any electro-magnetic scanner-devices is limited my resolution, it would be difficult to spot this nets, before they rip your ship apart with your own kinetic energy. BUT even if the chances to hit a ship with this kind of "kinetic mine" are low, the mere existence of such a thing would cause demoralization when flying across a probably mined sector. Imagine a post war solar system, where you could die every second because of a (too small to be detected) stray "mine-bullet". ]
[Question] [ In a feudal kingdom, a knight was granted a small island in the middle of a large [river](https://en.wikipedia.org/wiki/File:Rhein_Mainzer_Becken_stromab_von_Mainz_bei_Eltville_und_Erbach_vor_Bingen_Foto_2008_Wolfgang_Pehlemann_Wiesbaden_IMG_0263.jpg) by the king. The island is only about 700 square meters. The island is too small to have any significant population or a meaningful economy by itself but the king promised that the new lord will be able to collect plenty of taxes. Unlike the [Twins](http://awoiaf.westeros.org/index.php/Twins) in Westeros, the estate includes only the island, although nothing is mentioned about the water sovereignty. * The geography, climate, technology and population density are similar to those in England, Benelux and Germany in the 13th century. * The island is located in the middle of an important river. It is the major crossing in the region. A bridge was built on it, linking the two banks. * The capital of the kingdom, a city of almost 25 000 people is located on the west bank, not too far from the bridge. The island is still unsettled but our new lord has great plans for it. He wants to build a large castle made of stone (as large as there is space available). However, I wonder if this is possible. His only source of revenue will come form the tax imposed on people and goods crossing the bridge. --- Considering that this is a "busy" road, can he realize his dream of building a castle? Could he have other revenues? Bonus if he can do it without upsetting the merchants and the other nobles around. [Answer] He can absolutely achieve this goal, and do so without causing to much of a fuss (if he has the patience to not build it all right away). Medieval castles were not built overnight, so there is little need to tax the proverbial pants off of the people. Castles went through stages, perhaps a wooden palisade to start and a smaller stone keep. Over time pieces can be upgraded with stone, towers and gatehouses can be added etc. This could potentially take the lifetime of the knight, but it doesn't have to. Now, when it comes to paying for it the lord should not focus solely on taxing traders. The purpose of a castle in the middle ages was to provide fortification sure, but more importantly it gave the lord a base of operations to control the surrounding countryside. In such a location the lord is perfectly suited to develop and build a larger community around the castle, this would likely happen naturally in this instance so long as the lord kept the surrounding area safe from bandits and the like. Towns like a fresh water source and it is also important for farming. A castle likely can't support itself for long without a supporting population center anyway. Eventually it would evolve from a simple castle on an island: [![enter image description here](https://i.stack.imgur.com/kHjIp.png)](https://i.stack.imgur.com/kHjIp.png) To a castle with a surrounding town, which would result in surrounding farmlands and commerce increasing: [![enter image description here](https://i.stack.imgur.com/G2cju.png)](https://i.stack.imgur.com/G2cju.png) Eventually the lord could wall the surrounding city as well. This gives you another tax base (the local population) from which to pull funds for castle building. (oooh I added docks to the picture!) [![enter image description here](https://i.stack.imgur.com/9gzWx.png)](https://i.stack.imgur.com/9gzWx.png) [Answer] Diversify the knight's income streams and it shouldn't take long The knight has a really great location and the simple answer is to charge tolls to cross the bridge. That works but it doesn't tap into the many different revenue streams that could be realized from such a great location. Besides, everyone hates taxes but if you're providing a valuable service then the mark up can be far far higher than what you'd get from taxes alone. Build a castle that's a "Fireproof" warehouse then charge storage fees. Castles have always been a place to keep valuable stuff. Offer that kind of security to merchants so they can store their products without worrying about it. Invent Fire Insurance and insure your warehouse/castle though you'll need to invent accounting too. Give merchants the option to pay you a reasonable fee so if their goods are lost while in your castle, you will pay them the cost of their goods. If you build your castle right, you shouldn't ever have to pay out or pay out very rarely. Offer docks on your island for merchants. If a merchant knows they can offload their cargo directly into secured storage that decreases their risk. It's also good marketing and increases the emotional association between the knight's castle and security. You can charge large fees for docking up. If so inclined, have a trusted set of longshoremen to load and unload the cargo. That's even more money to be made. Secure River Rights If the knight can secure the water rights to the opposing shores, then he can build a large series of docks that will increase commerce through the area. The capital outlay to build the docks may be high but this investment can be recouped in a few years if commerce is good and the king isn't anti-business. [Answer] # Yes. It has been done before. Religious Sentiment Your nobleman could include on his teeny-tiny plot of island a religious structure and within a generation, it could become of significance to travelers. For a small fee, they can receive their blessings; for a larger fee, they can be assured safe travel. This is not dissimilar than the autonomous, but powerful [Mont Saint-Michel](https://en.wikipedia.org/wiki/Mont_Saint-Michel), which at times served this purpose. Boarding Not just people, but animals as well. Wealthy travelers would welcome a safe and fortified location for a stop along their way, whether for trade, pilgrimage, or noble duties. Treasury A secure castle like the one you're describing, with such defense, is a formidable place to hold your kingdom's treasury. Although autonomous under your prince, there will be wealthy and powerful benefactors who would risk anything to protect you. This was done at a place I visited in Lithuania called [Trakai](https://en.wikipedia.org/wiki/Trakai_Island_Castle) Island Castle. Natural Resources While you're describing a river, there are places with precedence in the sea and on freshwater, with close access to natural resources. Bahrain and Delma Island (in the Arabian Gulf) have been written about for centuries in 15th century Venetian literature for their access to rare pearls. Select a natural resource, maybe even gold, that is precious and found in your river that you have autonomy over. Exploit it. Be careful Be careful with your size restriction. There are restaurants with the size of your castle's footprint. If your story allows it, consider expanding the floor area. If not, no worries: I've been to a [tiny, island castle](https://it.wikipedia.org/wiki/Isola_di_Loreto): they do exist! [Answer] To join the chorus: It is a great location. And business is about location, location, and yellow rubber ducks. Which did not exist in the Middle Ages and can be ignored. First, if a king gives you an island with two bridges that connect the two banks of the river, it is because he wants you to protect and maintain the bridges and protect the boat traffic on the river. So regardless of who controls the river you will be expected to collect tolls on both the traffic crossing the bridges and going under them to pay for the maintenance and soldiers needed. You would also be expected, if not outright required, to fortify the island to secure such an important strategic location, and would probably receive some royal stipend or valuable privilege to pay for that. So you absolutely could get your castle. Althought it would probably would start as wooden palisades and gatehouses. Rely on good location instead of expensive masonry for defense. This would then piece by piece be upgraded over time to stone construction. Although for an island, barring some specific threat, such as a bordering state with large army, an actual castle might not be necessary. Much depends on whether the river is navigable by warships. Also note that the location really is valuable. Unless it is right next to a city it would be a secure stopping point for merchants. Brigands were a real problem in medieval times and an island with a palisade and armsmen for protection would be very welcome. Especially if you have to stop to pay tolls anyway.And people would pay for protection and food and drinks. Also for traders going away from city, basic supplies might be cheaper to buy outside the city, so the island might be a good spot to sell supplies. You can also have a transshipment business. Transporting cargo and selling and buying it in the city are two different skill sets. If business is good enough for merchants to specialize in one or another a secure location near the city for the cargo to change hands would be needed. The lordof the island might even take care of the transport between island and the city himself. The king might have been persuaded to give him some trade related privileges for transporting goods between the island and the city... Such privileges were a popular method for kings to pay for strategic castles or maintenance and protection of trade routes since it isn't necessary for the king to part with actual money. [Answer] It's a good spot! The knight can impose taxes both on traffic crossing the bridge and on boats passing under the bridge. Such a construction was perfectly legit in the middle ages. It only became offensive when a royal permit was missing and/or for exorbitant rates. Reference: <https://en.wikipedia.org/wiki/Road_toll_(historic)> [Answer] First any tax will upset nobles and merchants. But not only will he be able to tax those using the bridge, but those using the river to transport goods up and down river as well. Having a castle/defensive structure on the island would give a bit of power for backing up the tax on both fronts. The biggest issue is can a large defensive structure be build on the island? many islands are sand bars, which would be useless for a castle, but if it is there because of a rock outcrop that hasn't been washed away by the river then you have a reasonable chance of being successful. Of course having cannon to both threaten and protect will help a lot. One thing that would reduce the unhappy merchants and nobles would be if your taxes are fair AND you use your power to keep banditry down around the bridge and along the river on both banks in both directions. Cannon overlooking the river and possible chains across the channels that can be raised and lowered to as threats to river traffic to stop and pay their dues. [Answer] I'd like to join the chorus but if everyone does, things get boring, so I choose not to: ## Your knight got screwed. He has a small island but no "anchor points" on either side of the river. The existing bridge likely already has an owner (There are other lords on either river bank, right?) who will be displeased to have the bridge taken away. The king promised "the new lord will be able to collect plenty of taxes" probably without ensuring to keep it. After all, he said nothing about water rights. Well that's politics. ## However his situation is not too bad, if he's clever (and a bit ruthless) First he needs to find out the status of the bridge. * Is it good or will it need repairs soon? * Are there any claims on it and if yes, how strong is his claim in comparison? Finding out the claims does not need to be easy. There's no central register. Any close city might have something in their records but a written contract in some private drawer might be lurking around, too. In medieval times credits were usually paid back by nobles in terms of "royalties" (pun likely not coincidental but etymological). The noble got money now in exchange for lending his rights at something later like a source of tax income for a certain amount of time. This means the bridge as a tax source might be lend off to a rich family (the forerunner of banks) only to fall back to him after the time agreed in advance expires. The bank gambles on the income in the near future. They will calculate carefully to make sure they'll get their share. This might already be the case. If so, the bank has a strong but time-limited claim. If not, any other claim (by other lords) can be circumvented: The knight should address the king with concerns about the state and load of the bridge. He proposes to reduce the load on the already run-down (even if it's not) bridge to allow for repairs, if he gets in writing the right for taxing any new and old bridge located once the length from his island to the capital downstream and twice upstream (supposing the capital is located upstream, otherwise vice versa) regardless of previous arrangements. If he's able to get that, he has royal decree that nullifies any claims and ensures he will always have the closest bridge to the capital. Plus he doesn't need to repair the old bridge, because he only assured to allow for not actually pay for repairs on his own. Next he gets a credit lending out tax rights on the old bridge. The bank is bound to ask for the use of the money: "Constructions, I want to invest in my land to make it prosper by attracting more trade." The bank will likely agree, because more trade means more income from the bridge, which they will get. Now the old bridge isn't of any concern for him. He already got a fixed share of the money beforehand. If there are any claims: Sort them out with the bank yourself! He invests the money into building a new bridge. The bank will be pissed, because he'll be cutting their tax income with the new bridge: "But I said I'll invest in constructions!" With the two concurrent bridges, tax will be low attracting many merchants. The knight can increase the tax, as soon as the old bridge falls back to him. In case there are strong claims over the old bridge, he can also sabotage it. He should only do so after the bank's claim expired. No need to anger them too much. Now for water rights: He can have some bandits coming along the river. Attracting bandits shouldn't be too hard. If everything else fails, have some loyal men play them. The bandits anger the king a little. And the knight reports his watch saw a boat escape along the river around that time. However he was unable to do anything and still is, unless he's allowed to deploy some chains across the river to stop and check travelers. This should clarify water rights right away. Now the Knight owns two sources of income: * water rights * new bridge (low tax at first) He angered the bank but pleased the king (securing and extending an important transport route, defending against future assaults from the river) and merchants (low tax). Investing the income into building his castle step by step is the feasible way to go. It's unlikely he gets any credit after the stunt he pulled on the bank. As an alternative, agree with the bank to finish the new bridge after their claim expired. This will keep them happy and taxes up. However it will attract less merchants. [Answer] A 700 square meters island is smallish (20m \* 35m), but it is a good start. If you wish to build a castle, and extend your influence, you will: * have to increase your revenue streams * extend the surface on which you can build Let's start off with revenue streams. First, bridge tolls. In the medieval era, in order to cross a (deep) river, there were only two solutions: bridges and barges. Barges were inexpensive to setup, but they had a very limited throughput, required a calm river and getting horses on them could be a pain. As a result, your bridges will be highly prized by merchants and travelers. Second, river tolls, if the bridge arches are high enough for traffic to pass under then you can collect tolls in order to maintain the bridge. Note that medieval bridges generally had low arches, so only modest boats would pass under them. Make it so that the bridge piles have a slight "outcrop" just above water level where your toll collectors will sit all day long. Note: if your castle is close to the sea, then the ability to shut down the traffic upriver can be valuable security-wise; Paris was invaded by Vikings because it lacked such protection... Third, transfer fees. As mentioned, medieval bridges had low arches. As a result, higher boats will not be able to pass under it. That's a good opportunity for business! Rather than apply a toll, you can instead foster independent transfer crews... which will pay you a license fee of course. However, with 700 square meters, that's about it... so we need to look how to extend this. And here is the perfect answer: [![Ponte Vecchio, Italy](https://i.stack.imgur.com/JQynT.jpg)](https://i.stack.imgur.com/JQynT.jpg) When all you have are an island and two bridges, you need to make the most of them. In our case, this means extending them, gaining space on water: * you can extend the island (in the axis of the river) * you can extend the bridge (in width and height) There are several ways to extend. First, moored boats. It's frequent today in Paris or Amsterdam for example to have barges moored on the river side. You can even rent some... but back to our island, since you are providing protection, it seems natural that people will start mooring their boats here. Well, why not a tavern barge? An inn barge? And of course, you collect rent/taxes... Second, floatsam/piles. The natural extension to moored boats is to built on piles or floatsams. Encourage it, and once again collect rent/taxes. Third, extending the island/bridges. You can either build yourself, or you can lower taxes/rents for people who would build it (for some time). Note that the larger "stable" surface you have, the larger "unstable" you can get, and the more activity of course. [Answer] ## River, not the bridge In such a medieval situation, the river would likely carry more trade than the bridge, and have less competition - i.e., road traffic might be diverted to another bridge, or even cause another bridge to be built, but major rivers often have no good alternative. Thus, no matter what the neighbouring lords do, they will be able to extract tolls from the traffic flowing along the river. ]
[Question] [ The Background: I am going to be asking a series of questions that will be relevant to forming some sort of a picture of human space commerce. Let's say that Earth-based human civilizations have discovered a series of ancient jump-gates that allow them to travel within a large and varied interstellar network. There are not many clues, apart from the jumpgates, as to who left this system behind. For the moment, I am assuming that there is no bias to the kind of systems included in the network: i.e. its not like systems with earth like planets make up the majority of the planets in the network. So, "system types" have roughly the same probability of occurrence as if one were just taking a cross-section of space and scanning it. Put another way, the gates simply connect a large number of close-by star systems, rather than a large number of only useful star systems. While genetically-engineered humans exist in this "universe", no sentient non-human aliens have yet been encountered. The Question: If a space faring civilization can build space stations, why would they ever bother with planets? For resources, space stations could be built around asteroid belts. Otherwise, space stations may be placed in almost any orbit or other stable configuration. So, what might planets offer, that stations simply cannot? If terraforming technology exists, assume that it is time consuming (centuries). [Answer] There's a couple of upsides, plus one obvious large downside. First, planets are much more robust than space stations. A full ecology has a lot of depth, layers and layers of life and interactions. That depth allows it to absorb disasters and keep ticking - it doesn't negate the bad effects, but it means they are less likely to wipe you out. A disease that eats your corn crop means you go hungry, but you survive on potatoes. On a space station you have a smaller, technology-enabled ecology that's rather shallow, which means it's going to have a lot more points where only 1-2 things can fail and your entire space station becomes unhabitable. If your algae vats get corrupted, you're out of food and air, and you might not have a quick enough solution to keep people alive. Second, planets are already there. Building a city on a planet has start up costs, sure. But building that same city has the same start up costs, plus you need to build everything the planet gives you for free - air, water, food, gravity, and the space itself. Space stations are also 3-dimensional builds, which requires more material than a 2-dimensional city for things like infrastructure. If this doesn't seem important for a city, think about the cost of creating a cattle ranch in space vs on a planet. Finally, the counter - a planet is deep inside a gravity well, which negates some of the benefits listed above. Getting in and out of gravity wells can be incredibly difficult unless you have something like a [Space Elevator](http://en.wikipedia.org/wiki/Space_elevator) to help you, which increases those expenses greatly. [Answer] If humans can build condominiums, then why would anyone live in houses? ## Angular Velocity We know only two ways to simulate gravity. One uses the mass of a planet. The other uses spin. It has been speculated that humans might find some aspects of spin-based gravity uncomfortable. For example, certain kinds of motion (nodding or shaking one's head) may cause odd sensations in the inner ear. ## Natural Geography Some people may simply prefer natural geography to artificial geography. For example, a mountain climber may prefer a planet because the mountains are taller. Or because the mountains are more variable. Or because there's simply a greater variety of mountains on a planet. ## Size Compared to a planet, space stations are small. If one likes to see new sights, one may well prefer the sheer variety available on a planet. Or perhaps flora is your thing. Or fauna. Maybe you like undersea exploring (how deep are the seas on a space station?). ## Stubbornness "My parents lived and died on a planet and so will I." Even if energy and raw materials are cheaper on space stations, some people may still prefer planets. Just because. ## Anti-technology A space station is built with technology and runs on technology. It's hard to envision an Amish lifestyle on a space station. [Answer] While many of these answers are pretty good, I think there's one very simple reason people would use planets over space stations. It's been said before, but I don't think enough emphasis is placed on it yet. # Planets are Incredibly Big Seriously; there's 7 billion of us living on a fairly moderate sized little hunk of rock, which consists of 70% uninhabitable ocean, and even of the 30% of land that it has, most is uninhabited. Doing a quick conversion of the Earth's land area (estimated at 150,000,000 square kilometers) divided by the number of people on earth (estimated at 7 billion) shows us that the average amount of land available to each human currently alive is 21400 square meters. (Which is about 5 acres) That means if the Earth's land area were fairly divided amongst the people living today, every person would have an area of land big enough to build about 100 houses with gardens on. [This answer](https://worldbuilding.stackexchange.com/questions/10242/how-would-life-evolve-on-an-over-urbanized-earth/10294#10294) to a question about overpopulation says that the Earth could house as many as 2.7 trillion people if we were to convert most of it into cities. You're not going to be able to build enough space stations to ever compare to the kind of ground area a planet supplies. When you hear "a planet is larger than a space station" it's easy to miss by just how much the planet is bigger. Although technically, if you have so much energy you run out of other stuff to do with it, you could consider taking apart the Earth entirely and converting it into space stations. If we take a look at the weight of the Earth (5.97219 × 10^24kg) vs the weight of the International Space Station (450.000kg), then the Earth would provide enough building materials to build 1,327,150,000,000,000,000 ISS sized space stations. That's roughly 1,895,000,000 space stations (almost 2 billion) per person alive today. Of course, we'll not go into the cost in terms of energy or labor for doing so, considering even a single ISS costs upwards of $150 billion dollars. But yeah. Planets are big. And they're just floating there. I don't see why you would not use them. [Answer] Valuable to whom exacly? Sure, to the ruling elite planets are deep holes; and even if it was covered with pure gold it wouldn't be worth the fuel required to fetch it. All that changes when you consider moving there. A couple of robo-miners, a fabrication box and you can live out your life in luxury. Throw in a genetic variation set and your family can last forever. And when you have a population of 5 billion: it's still pointless trying to export steel; but information doesn't care about gravitywells. Just imagine the scientific experiments you can perform when you have free gravity and a massive neutrino-filter just below your feet. Software is also exportable; the latest mobile phone has all the "Angry birds"-clones of a thousand planets at your fingertips. Bitcoin; and other computation time is also easily exported. All of this is mostly true for the interstellar empire as well. There just isn't that much to expect from other planets/solar systems than more of the same. Exporting steel from one solar system to another; why bother? [Answer] Just to complement the good answers already here, let me bring up defense. Specifically, camouflage. Suppose a hostile environment in which your enemy might track your gates or your movement through them. If at the end of the gate there's a space station, the enemy can just shoot away. You may have to place your base astronomically far from the gate to give them a search problem. On the other hand, if there's a planet with permanent cloud coverage, and your base is over a few dozen miles from the gate, the enemy is now lost, regardless of whether the gate leaves them out of or in the planet (you didn't specify). Of course they can explore, but likely they were detected when exiting the gate, and your own defenses can do their thing. Additional precautions may be having false tracks in different directions if the gate is on land, or having supply ships change course below the clouds if the gate is in space. As a downside, though, a base in a planet is very vulnerable to bombardment from space once the enemy knows where it is. No warheads needed, just throw rocks at exactly right angles. [Answer] Others have covered some very good points. I'd just like to add the following: Rare Resources - organics While it is highly probable mineral resources could be extracted from asteroids or other small bodies the complex organics created by life are unlikely to be present in any quantity off of significant planets. While we are slowly mastering genetic engineering there are now many plants that cannot be grown outside of their original habitats and we understand the ecology of Earth from thousands of years of study. A plant, fungus or something entirely new that has a medication like effect on people might not be easily created outside it's home environment on an alien planet. Obviously trade in something like that depends on very low cost to planetary travel but the neat thing about hypothesizing about things like this is that costs are likely to be high at first but decline over years until they are trivial. Rockets are a resource expensive way into space. Self replicating, self assembling nano built beanstalks could be much less so and given a few thousand years such imaginary technology looks less and less like magic and more and more like something you could do with your phone. Will our understanding of medicine or life on other worlds and how to farm it grow as fast as our travel technology and make it so everything we ever find could be grown everywhere? There is no way to know. [Answer] Gravity Once your space-faring civilization enters a new star system, they still have to get around on their own, and can use (particularly massive) planets for gravity assists. The other benefit to gravity is that a planet with similar mass as Earth can offer a lot of space to stretch their legs. Resources We only speculate what resources are available on exoplanets, but they [vary greatly](http://en.wikipedia.org/wiki/Exoplanet#Physical_parameters) in size and probable composition. If a particular resource (water/ice, oxygen, etc.) it's possible that at least one planet in each candidate star systems has what your civilization needs. And LOTS more of it than a comet or asteroid can provide. Protection If any of the exoplanets have an atmosphere to protect from space debris, or can protect from harmful radiation, then it would be a great place to make a cheaper 'space station'. Geology / Morphology Rocky and gassy, [all-water](http://en.wikipedia.org/wiki/Ocean_planet#Examples), and acid-raining planets would be so cool to explore to understand processes on our own planet, as well as provide evidence of potential life. [Answer] ## Mining Camps Tectonic processes concentrate ores. We don't know the mineral distribution of the asteroids, but it is likely that they did not have tectonic processes to concentrate ores (there may be other things which cause concentrations... but...) Gold may be rare, but it comes in mother-lodes in tectonically active planets. Ditto for rare earths, etc. Planets may end up as nothing more than mining camps, and the odd-ball or two who likes natural settings. [Answer] So beyond any doubt all Interstellar Commerce which appears now imminent this Year 2021 will revolve (so to speak) around the Earth's Moon and in particular the Far Side of the Moon as A: it offers an enormous potential for privacy which is at the moment anyways unavailable for all of us beholden to this the most spied and pried upon place known but for even more importantly B: The Moon is both massive and not very far (perhaps a week's worth of travel to there and back.) Depending on the economics of "travel and stay" i think a single Month "off World" as very much in the realm of possibility for those in the business of doing said business (say trading in physical metals or something that requires incredible amounts of energy.) There is of course the possibility of creating a kind of "Shipping News" effect for Deep Space Travel as well so if not an actual Newspaper of course the idea of humans attempting to travel into Deep Space and returning to talk about makes for a uniquely human attribute as well. It is interesting to posit that the time for such a curiosity to be realized is right now, today Year 2021 but yes absolutely I believe now is that time. What that means if true I have no idea but hopefully as the Human Race realizes this as true such speculation will explode. So far still pretty silent tho.. ]
[Question] [ An answer to the following question mentions a free online calculator for long-distance space travel. [Software to ease my interstellar travel calculations](https://worldbuilding.stackexchange.com/questions/33757/software-to-ease-my-interstellar-travel-calculations) I'm looking for a 3d simulator that accurately and visually shows transition from orbit and other aspects of interplanetary (rather than interstellar) travel. I don't care about trading between planets or social interactions or wars - just the travel aspect. I'm thinking of purchasing Kerbal Space Program, <https://www.kerbalspaceprogram.com/en/> which although it has cartoon green aliens as an extra, does, I've heard, have accurate physics. Does anyone have experience of this software? Will it serve my purpose? Does anyone have other recommendations? Requirements I'm hoping for software that shows heavenly bodies and spacecraft visually and in 3d from variable points of view, preferably with a zoom facility. The graphics don't have to be ultra-high-definition, just easy to recognise. I want to take account of amounts of thrust/fuel needed with realistic rocket equations built into the software (so I don't have to do them!) and to be able to travel from orbit around the home planet to orbit around the destination with course corrections where necessary. Takeoff from the planetary surface would be a bonus but not vital. Worldbuilding - I want to build a fictional solar system with fictional planets but that has exploration and so on with realistic physics.Therefore the ability to place fictional planets around a fictional sun is highly desirable. NOTE: There is a tag especially for software-recommendations so I don't believe this question should be closed as 'opinion based'. There has been some difference of opinion about whether to use 'hard-science' or 'science-based'. I've finally settled on the latter. I don't want rocket equations in the answers, I just want the software to be as true to real physics as reasonably possible on your average Windows 10 machine. EDIT: I suppose I was hoping for something where I would say, "I'm in orbit on planet X and I'd like to be in orbit on planet Y - Please show me what fuel I need to carry, how long it will take me and the optimum trajectory". Judging by the answer by PSquall, I guess that's a very big ask. If that's not available then the nearest approximation will do nicely. [Answer] Kerbal Space Program is an homage to the developments in the Space Race of the Cold War. You will see names like [Wernher von Kerman](https://wiki.kerbalspaceprogram.com/wiki/Wernher_von_Kerman) or [Gene Kerman](https://wiki.kerbalspaceprogram.com/wiki/Gene_Kerman) to remember the old Apollo and Gemini flights, but even near-future propulsions are implemented, although the game doesn't take itself too seriously. The simulations are, as Mołot stated in his comment, not n-physics based, but work with [Sphere of Influence](https://wiki.kerbalspaceprogram.com/wiki/Sphere_of_influence). On top of that, the Kerbal System (the equivalent of the Solar System) is roughly 1/10 downscaled to the real solar system, but still with the same surface gravity. Overall, I would say the feeling is much the same, the orbital mechanics are the same, but with many differences in technology. I recommend it, if you want to learn the basics of orbital mechanics in a practical way. Two points I need to add: * The game is not easy. It is literally rocket science. * If you don't like the simplifications made in the simulation, there are mods that overhaul the complete game. Real solar system, accurate planets and rocket engines with equivalents in the real world, even an [n-body simulation](https://forum.kerbalspaceprogram.com/index.php?/topic/162200-wip131-14x-151-principia%E2%80%94version-%E1%BC%90%CF%81%CE%B1%CF%84%CE%BF%CF%83%CE%B8%CE%AD%CE%BD%CE%B7%CF%82-released-2018-11-07%E2%80%94n-body-and-extended-body-gravitation-axial-tilt/). But, all these modifications make the game even more complicated and harder. The game on its own is very laggy, depending on the size of the simulated rocket, so modding it even further most likely won't make it any better. And if you really want to take a look at planetary transfers, look for the [Hohmann Transfer](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit). That is the basic for every current interplanetary transfer [Answer] If you are content with flying around our solar system, I'd recommend the [NASA trajectory browser](https://trajbrowser.arc.nasa.gov/traj_browser.php). It lets you find realistic flight paths to many large and small objects in the solar system, for example starting from LEO and inserting into an orbit around Europa. The browser assumes standard rockettry, meaning flight plans using discrete burns with a defined delta-V to reach your destination. Sci-Fi stuff like constant acceleration rockets cannot be modelled. By playing with the maximum allowed delta\_V you can simulate more powerful rockets. You'd still need to calculate fuel loads manually ina spreadsheet or similar, using this form of the [rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) for each burn (start your calculation with the last burn, as the fuel for the last burn is part of the payload for the second to last etc.): $M\_f=1- e^\frac{\Delta v}{v\_e}$, with $M\_f$ the propellant mass fraction and $v\_e$ the exhaust velocity. $v\_e$ is another parameter you can play with to get more science-fictional rockets. How does this stack against your requirements? * 3d view - no * graphic representation - yes, simple/abstract * travel times - yes * fuel demand - only with the help of a spreadsheet * fictional solar system - no [Answer] STK, <https://www.agi.com/products/engineering-tools> , is a tool used in creating many such visualizations by NASA, SpaceX, etc. It's an engineering tool, so it's very realistic, but it might be a bit too much for a lay person. [Answer] ## Universe Sandbox <https://store.steampowered.com/app/230290/Universe_Sandbox/> Very pretty, and as accurate as you are going to get on physics without a supercomputer doing detailed sums. A little bit short on autosolving transfer orbits and such unfortunately. [Answer] I can't believe no one's mentioned Orbiter 2010! Its similar to KSP, but without the building part, and with full-scale, n-body physics. There is a mod for it called Interplanetary which allows you to input your location, your destination, and the maximum time you have to get there, and it will tell you how much dV you need and give you a trajectory. [Answer] I would go for Kerbal Space Program as well, but here's a game I recommend you have a look at alongside KSP: # [Rogue System](http://imagespaceinc.com/rogsys/) I like this game because it tries to do something new and different. It brings a [DCS](https://www.digitalcombatsimulator.com/en/)-style level of simulation, but to a space game. Yes, this means that it simulating something that doesn't exist, but the game's author has produced something that, to me, feels real. Unlike KSP, with moveable cameras and views, in this game you only see the world through the eyes of your character. It's still in early access, but in my view there's plenty in the game to keep you occupied. I still haven't completed an orbital transfer in this game. In KSP I've sent manned missions to Duna (KSP's Mars), have landed multi-part bases on the Mun and Minmus, and remote probes to all corners of its solar system without problem. In Rogue System I still have trouble turning on my engines. [Answer] # Goddard Mission Analysis Tool GMAT is free software from Goddard SFC that can do most of what you are asking to do, provided you already know a little about orbital mechanics. [You can find it here.](https://software.nasa.gov/software/GSC-17177-1) It has Windows and Linux binaries, and can be run from a GUI or in script mode (you want the GUI, I would imagine). I use it occasionally at work for some geocentric orbits, but it is specifically designed for interplanetary missions. The documentation is pretty good too, and there are several examples you can tweak to meet your needs. I used their Earth-Mars transfer example and got it running in about 5 minutes. Here are the screenshots: [![enter image description here](https://i.stack.imgur.com/Q8odF.png)](https://i.stack.imgur.com/Q8odF.png) [![enter image description here](https://i.stack.imgur.com/Y68i1.png)](https://i.stack.imgur.com/Y68i1.png) [![enter image description here](https://i.stack.imgur.com/wqsgv.png)](https://i.stack.imgur.com/wqsgv.png) The celestial bodies can be customized (planets added, removed, moved, increased in size, etc) so it should be good for a fictional solar system. Good luck! [Answer] If you're just looking for required thrust, then take a look at some of the calculators created specifically for Kerbal Space Program, like this one: <http://ksp.olex.biz/> Here's a comprehensive list: <https://wiki.kerbalspaceprogram.com/wiki/Calculation_tools> ]
[Question] [ I have a world where certain species of dragon live along the coasts, eating off the fish from the sea. I like the idea that they can fly through the air and swim in pursuit of fish but I'm not sure that would be practical because the wings would cause drag. I'm also not sure whether they would even need them, because once they've got the sea who needs the air? [Answer] As you pointed out, the large wings needed to sustain flight in air would become a problem in water, causing excessive drag. This however doesn't make it impossible. I think you have two choices: 1. Dragon penguin style: ability to fly totally lost, shortened wings to enable agile maneuvering in water. The sea is their main habitat (food harvesting and movement), and they use land for nesting. 2. Dragon seagull/cormorant style: they keep the ability to fly but they are able to retract their wings while diving into the sea for fishing. They can do some maneuvering underwater to chase their prey. Air is still their main habitat, sea is used to gather food but not for moving, dry land is used for nesting. [Answer] The real world has plenty of examples of birds that ca swim brilliantly, so obviously wings aren't a disadvantage per se. However, there are a few caveats: * Wings consist of very large surfaces, which means increased drag. This can be mitigated by folding the wings away. Dragon wings are bat-like, which means they fold quite neatly - in fact, because skin stretches while feathers don't, you might be able to fold them better than a bird can. * Aerodynamics are somewhat different from hydrodynamics. You may find that a dragon whose wings are optimised for flying can't really use them to swim very well, or conversely, a dragon who can swim excellently may end up a less-than-excellent flyer. However, besides the mechanical, there's also a biological aspect to consider. A bird's wings are mostly feather. Feathers are not living tissue, do not require blood supply, and are very good insulators. This allows swimming birds to extend their wings more or less with impunity underwater, and to retain their body heat while swimming. A dragon's wings, however, are batlike, meaning that they are mostly skin, and a dragon is covered with scales, which do not trap air like feathers. This means that a dragon will rapidly lose body heat when submerged, and the moment they extend their wings, they start to act like radiators and the dragon starts losing heat even faster. Given that dragons are lizard-like, you may decide that they are cold-blooded, which means that heat loss is a serious problem. It's not an insurmountable problem - there are aquatic reptiles in the real world, such as swimming snakes and the marine iguanas of the Galapagos Islands - but it does limit you to warmer waters only. Alternatively, you could say that because dragons breathe fire, they have an internal source of heat, but even so, they probably wouldn't enjoy this rapid cooling. On the other hand, you could say that a dragon's internal fire causes them to overheat, and they use their dives into the sea to cool off so that they don't expire (or combust!). This could also answer your secondary question: why can swimming dragons still fly? A dragon who breathes fire might need to dip in the sea to cool off periodically, but their fire doesn't work so well underwater, so they never become fully aquatic. If they nest above water, then they're at risk from predators and egg thieves. Nesting on cliffs or high places makes it harder for most things to reach them, which gives them a reason to retain the ability to fly. At that point their main threat is birds, who use feathers, which fire is quite effective against. In fact, fire may be more effective at nest defence than at hunting; provided the cliffs (or wherever the nest is) are largely non-flammable (so that the dragon doesn't catch itself in a forest fire), breathing fire into the air from a static, grounded position is likely easier than trying to breathe fire on a grounded target while flying over it - not to mention that using fire to hunt may result in a meal that is either unreachable due to being in the middle of a brushfire, or inedible by virtue of being mostly charcoal and ash. Thus, you have a creature that uses fire to defend their nest against the birds who are able to reach its inaccessible location, while frequently taking dives into the sea to cool off using its large, radiator-like wings to avoid self-inflicted heatstroke or self-ignition. [Answer] It depends on the dragon. Western mythological dragons look like pterosaurs, while Eastern (asian) mythological dragons are much more snake-like, and they don't even have wings. After all, they fly because of magic so, why should they need wings at all? An asian style of dragon is an excellent swimmer, just like snakes or eels are, and there's no problem with wings. [Answer] Look for analogy. There are birds. Some of them fly, some swim. They are like dragons, really. Except it takes a lot of work to make dragon flight possible. We have birds that can't fly at all. We have some that can only on the surface, wings above waterline. Then we have wing propelled and foot propelled [diving birds](https://en.m.wikipedia.org/wiki/Diving_bird). You just need to read more about them and you'll see how it affects wings. Generally birds that use wings in water evolve smaller wings and no longer can, nor need to fly. Just as you stated in your question. The ones that use foot can keep wings close to the body and avoid drag. Some can fly all right. Some gave up the sky. You can feasibly apply any of these to your dragons. You can even have few varieties, why not. [Answer] Another possibility to consider is the carapace, like some insects (mostly in the beetle family) have. Essentially, the flying wings fold up and are stored under the hard carapace, which is split and moves out of the way when the wings are to be extended for flying. If the carapace is shaped such that your dragon's body is hydrodynamic when the flying wings are not in use, you can then have a different propulsion mechanism for in-water movement. The downside is that beetles aren't really efficient flyers, even among insects - and there's probably a point where the mass of the carapace makes it unreasonable, meaning that you're quite unlikely to have large dragons. [Answer] If wings cause drag, then just fold the wings up when underwater. (Note: This may work better for short periods of time.) Proof? [See this.](https://www.youtube.com/embed/rbkD4ULPYyU?start=0&end=35&version=3) ]

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