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[Question] [ In countless zombies books, from World War Z to The Walking Dead, prisons are depicted as being the ultimate refuges for surviving the zombie apocalypse. The Zombie Survival Guide by Max Brooks dedicates 6 pages up it, whereas other refuges get only 1-2 pages. While this argument holds obvious merits, I still have doubts. One obvious problem is that the people already there are there for a reason. Murderers and Rapists would be there waiting for you. Another is getting in. Prisons are just as hard to break in as to break out. In a walking dead style apocalypse, would prisons be the safe havens they are painted as? What would get in the way of this? [Answer] Prison complexes may well be very defensible. Obviously a cell block on it's own is no good, you'll run out of supplies. But many prison complexes range from minimum to maximum security and have a lot of land and quite often farms in suitable areas for farming. So crops would already be in the ground, fences in place, security camera etc. It would be easier than trying to build defenses from scratch anyway you'd just reinforce what is there already. Your main problem would be the inmates. But if you got control of the outlying parts of the prison, they would eventually starve to death anyway and you could use them to fertilise your fields, or burn the bodies or whatever. > > Prisons are just as hard to break in as to break out. > > > No they're not, they're a lot harder to break out of for obvious reasons. The outlying prison grounds are probably no more than chain fences with razor wire. Quite possibly with living quarters for guards and other things. Minimum security prisons could probably be entered with bolt cutters. There would be more trouble getting into the maximum blocks (if you actually wanted to) but again it's just steel doors, if the guards are dead inside it wouldn't be too long before you came across keys, and the office areas are probably easier to enter than the cell blocks. Any outbreak in the prison would be localised due to locked doors rather than general, the vast majority of prisoners would be locked down so you'd find wings full of starved to death corpses locked in cells rather than zombies wandering everywhere. Even if you have a lot of zombies prisons are designed to funnel dangerous people, you only open the doors you need open creating a pathway to an enclosed area. So it should be easy to funnel them into a yard or something, just have a fast runner, unlock the doors all at once remotely, open only doors leading to the yard, have a ladder for your runner to the walkway, pull the ladder up after him. Block off access to the yard, mop up any strays. Flood the yard with petrol or whatever from the walkway and burn the zombies. Or leave them there, they can't do anything. [Answer] No. Prisons are miserable death traps before and after the apocalypse. And here's why... (cue music) Besides the aforementioned murderers and rapists, prisons rely on a constant stream of resupply. Not to mention that the vast majority of prisons, in the US at least, are desperately overpopulated. The population density in most US jails and prisons rivals major cities as far as people per square mile/km. And then there's the resupply problem. Yes a prison offers a nice castle, but what is a castle without food and fresh water? It's an expensive tomb. Also... Modern prisons rely on electricity to maintain security. Gates, cells, and passageway doors are often magnetically​ sealed. No power and the doors no longer work. Although most prisons will likely have a very nice storeroom, generators, and weapons; you can expect these places to either be ground zero, or much less fortunatly some of the last holdouts for paranoid, half trained, and well armed corrections officers. CO's are a very special kind of cruel. "Would you like to work in an environment where the vast majority of people would like to kill and/or rape you? Well we have a job opportunity for someone with your particular indifference to human suffering!" [Answer] To start with, what would one look for in a refuge for a zombie apocalypse? Without reference to any detailed guides, I would list the following as ground assumptions: 1. Isolated from initial outbreak (so you don't find yourself in the middle of a zombie population when you get there). 2. Easy to defend. 3. Self-sufficient - ready stock of food, water, weapons/ ammunition. 4. Comfortable: this is what separates the refuges from the havens, and since we're looking for havens in particular... How would a prison rate among these criteria? Isolation: depending on the security level of the prison, this could be quite variable. Let's assume that we are talking one of those maximum-security institutions for the hard criminals (in line with OP's later assumptions). In this case, there is a good chance that the virus would not have quite penetrated either the wardens or inmates, so the prison is clean. Furthermore, if contact among wardens and inmates is kept at a minimum, there will be little chance of any errant virus spreading too quickly. 8/10. Defensible: The high stone walls, electric fences, and watchtowers designed to keep prisoners in could be easily repurposed to keep unwanted zombies out. However, their effectiveness has to be questioned, because the main deterrent for prisoners (getting shot at) will not apply to zombies, and the zombies may find scaling those walls a lot easier than you think. Once the zombies have broken into the compound, the complicated system of iron-barred doors and gates (as I imagine it) could just as easily work against any defenders who are not completely familiar with the prison's layout. Discovering at the last second that the iron door between you and safety only opens ONE way would be comically tragic way to die. 4/10. Self-sufficient: Prisons probably have a stock of food in their kitchens, which is good because you won't be starving anytime soon. The only downside is that it's prison food. Weaponry should also not be a problem provided that one is able to break into the armories. 9/10. Comfort: Our maximum-security prison for hardened criminals is unlikely to be the Ritz. Amenities include bed, ensuite toilet, and your laundry done at reasonable prices. Also, the inmates may not be the easiest people to get along with (as OP assumed, although I can't be too sure), so do go in with an open mind. 2/10. Overall, the prison rates 58%, barely passing. You would probably rely on the zombies not coming across the prison as your primary means of defense; once they make any sort of attempt to breach your refuge you would not fare too well. In the meantime, you won't actually languish, but you might wish you were dead before long. Would not seek refuge again. [Answer] Prisons are a very good safe haven for multiple reasons but are not the best imho. If you assume zombies behave like the the Walking dead, then any building with more than 2 floors is a safe haven if you destroy the staircase/ladder and replace them with a rope. Zombies can t climb ropes so you are safe. Having a wall/fence adds another layer of security : DisneyLand, an abandonned military base, a school with a proper fence would be an upgrade. Having cells where you can barricade yourself is another layer of security. Prisons have all of the above so they are pretty good. However the best would be to add a moat. A castle with a moat would be ideal. Fences need maintenance and break after a while if too many zombies push on it. A moat is unbreakable, you would just need to regularly clear the moat by burning the zombies that fell inside to avoid filling up the moat with zombies. You could image a system of circles with moat/fences/moats/fences etc... with famrland and outposts on the outter circles and living quarters/command center in the center. ]
[Question] [ I have a roughly Earth-like planet in a solar system some distance from ours. The atmosphere of this planet is largely similar to that of Earth, but particularly, has a somewhat higher oxygen content; currently, I'm thinking about 26-28% oxygen (O2(g)) and 65-68% nitrogen (N2(g)), compared to Earth's 21% oxygen and 78% nitrogen. The surface temperature of the planet varies between about 230 K (-43°C) and 320 K (+47°C) depending on location and time of year. Compared to Earth's atmosphere, I would like to add something to the planet's atmosphere that has the following properties: * Concentration: a few percent by mass * At least extremely foul-smelling, ideally poisonous, to humans as we know them; doesn't need to be foul-smelling if poisonous; the higher the toxicity, the better, but beggars can't be choosers so I'll take what I can get * Does not pose a problem for local creatures that have evolved in such an atmosphere (this is an absolute requirement) * Reasonably evenly distributed among the other atmospheric gases (I don't want it to form a separate layer at some altitude where, if you can just avoid that, everywhere else is basically fine) * Can be maintained over time in a high-oxygen environment, possibly with geological replenishment (for example through volcanic eruptions) or through insolation breaking up some other gas that does get replenished on an on-going basis * Doesn't react with the rest of the atmosphere at the first opportunity I haven't really decided all that much about the planet's geography or geology, so if some aspect of that makes it easier or for that matter harder to pull this off, I'm open to input. I was thinking about methane, but that massively fails at least the requirement of non-reactivity in a high-oxygen environment. **Hence two very closely related questions:** * What gases might be good options to satisfy all the criteria above? * If all of the criteria aren't satisfiable using a single gas added to the atmosphere, then what is the closest I can reasonably get? [Answer] # Carbon Dioxide The simplest and most straightforward solution. * [Deadly to humans](https://en.wikipedia.org/wiki/Hypercapnia) at concentrations of around 10% (this is on the high end of 'a few percent by mass' but you said you will take what you can get) * Hypercapnia kills you by messing with the carbonic acid concentration in the blood. Since this is just a pH balance thing, it seems pretty easy for local wildlife to evolve to manage it. * CO$\_2$ will disperse through the troposphere and stay evenly mixed (see: Earth) * CO$\_2$ is one of the most common planetary atmospheric gasses (Venus, Mars) so it is highly likely to be present on planets to start with. On Earth, it was mostly replaced by oxygen through photosynthesis. However, if you go with an arid planet with few oceans and an order of magnitude or two less biomass of plants and algae, then you can explain why the equilibrium CO$\_2$ levels are so high. Geological and biological processes (the carbon cycle) will then maintain this level. * CO$\_2$ is stable in an oxygen-nitrogen atmosphere (see: Earth, also, too bad it does). As a note, a higher CO$\_2$ planet might be expected to have a higher greenhouse effect. However, if you also made the planet more arid and removed a lot the oceans, then you would have much less water vapor in the atmosphere. Since water vapor is an even more powerful greenhouse gas than CO$\_2$, you can argue that there is some point where these effects balance out, and distance to the sun is about the same. Regarding making the planet arid, I propose this breakdown. The Earth is about 70% ocean, 20% usable land, and 10% wasteland (Sahara, Antarctica, Siberia, etc). If you alter the ratio to 20% ocean, 20% usable land, 60% wasteland (giant continental deserts), you end up with the same relative inhabitable size of planet as Earth, and yet have highly reduced biomass of plants and algae. [Answer] **Nitrogen dioxide.** <http://emedicine.medscape.com/article/302133-overview> From <http://www.healthhype.com/silo-fillers-disease.html> > > Nitrogen dioxide damages the lower airways in particular and the lung > tissue. It breaks down into nitrous and nitric oxide within the > airways and lungs damaging the ciliated cells that line the airways > and the epithelial cells (pneumocytes) that maintain the air sacs > (alveoli) of the lungs. Type I pneumocytes are primarily affected in > silo filler’s disease. This results in inflammation of the bronchial > and bronchioles walls (bronchitis and bronchiolitis) and alveoli > (pneumonitis) along with fluid accumulation within the lung (pulmonary > edema). It is important to note that neither bronchitis nor > pneumonitis in silo filler’s disease occurs due to an infection. > However, patients with silo filler’s disease are at a greater risk of > developing infectious bronchitis, bronchiolitis and pneumonia. > > > I have read about silo disasters where workers encounter a pocket of NO2, are overwhelmed, and then additional workers coming in to rescue them are also overwhelmed. I think in concentration like this the NO2 is just visible - a heavy brown gas. In lesser concentrations it is an important component of smog. I was skeptical to read in this excerpt that the active moieties are actually nitrous and nitric oxide. I am skeptical about that - certainly nitrous oxide is inhaled essentially at 100% by kids at the dentist. Nitric oxide is a vasodilator and also not that toxic. Wikipedia states that > > NO2's health effects are caused by the reaction products or their > metabolites, which are reactive nitrogen species and reactive oxygen > species > which is more plausible. > > > NO2 can exist in equilibrium with O2 and N2 which is good for your world. Humans can put up with small quantities of NO2 for a while which is good for narrative possibilities. Biting, unpleasant atmosphere is more compelling that if your humans just drop dead from a breath. Re the natives: our scavenging /detox mechanisms can get rid of some NO2 and we can repair damage from the rest. A matter of degree like other toxins. If your natives have much more radical scavenging ability in their cells they will be able to tolerate more NO2. For humans you could have your atmosphere anywhere from the silo bottom (rapid death) to Beijing smog (no fun). You could have it vary day to day and place to place. [Answer] You could throw a bit arsenic in the atmosphere. A few years back there was talk of a earthbound lifeform that [used arsenic instead of phosphor](http://news.nationalgeographic.com/news/2012/07/120709-arsenic-space-nasa-science-felisa-wolfe-simon/). [Wikipedia](https://en.wikipedia.org/wiki/Arsenic#Bacteria) says (highlight by me): > > In 2008, bacteria were discovered that employ **a version of photosynthesis in the absence of oxygen with arsenites** as electron donors, producing arsenates (just as ordinary photosynthesis uses water as electron donor, producing molecular oxygen). Researchers conjecture that, over the course of history, these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive. [...] Although the arsenate and phosphate anions are similar structurally, no evidence exists for the **replacement of phosphate in ATP or nucleic acids by arsenic**. > > > Now I am no chemist. Arsenic is mainly dangerous for earthlings if dissolved in our drinking water, but it has forms that are dissolved in the air. High concentrations of arsenic (a few percent should be more than enough) should make your planet deadly for humans. It could be replenished by local phenomena just as it is replenished on earth and should stay in your atmosphere (or at the very least - your drinking water and soil). As for the smell ask chemistry student [Ryan Curry](https://www.quora.com/What-does-arsenic-taste-like): > > Several sources claim that most arsenic salts are tasteless, but may change the flavor of a food they contaminate (bitterness is often reported). One symptom of arsenic poisoning (like other metal poisonings) is a metallic taste in the mouth. > > > [Answer] You could try [hydrogen sulfide](https://en.wikipedia.org/wiki/Hydrogen_sulfide). It's not stable in the long-term in an oxygen atmosphere, but it could be continually renewed from biological sources, and you don't need a high concentration. You can have it be either smelly or fatal, but not both, since fatal concentrations paralyse the sense of smell and so can't be smelled. You'd only need 1 part per million to make your planet smell very bad, or maybe 100 to 300 parts per million to be lethal. [Answer] Sulfur dioxide. <https://www.cdc.gov/niosh/idlh/7446095.html> Site requires at least 30 characters. Why? I don't know. Venus has traces of SO2 in its atmosphere, it's certainly a possible gas. It would be an immediate health threat at about 500 ppm which is 0.05%, so a couple of % would be deadly. An alternative, or just an additional toxic gas is carbon dioxide. Its tolerated in much higher %, but between 7 & 10% produces unconsciousness. Note, Venus' atmosphere is mostly CO2. [Answer] What about [Ozone](https://en.wikipedia.org/wiki/Ozone)? It has a sour smell reminiscent of Chlorine, it's toxic at fairly low doses but not lethal until the dosage is much higher, it forms naturally in the presence of [UV Radiation](https://en.wikipedia.org/wiki/Ultraviolet) and [Methane](https://en.wikipedia.org/wiki/Methane) and what it doesn't kill adapts to otherwise lethal doses in a space of hours. Ozone decomposes in the presence of Oxygen but it forms fast enough in the lower atmosphere to be a health risk in modern day cities where smog gives it unburnt organic molecules for a catalyst. A planet with a lot of UV from a bright star, say white or blue spectral type, and an active anaerobic carbon cycle, so plenty of methane and even ethane in the atmosphere, would have a diurnal toxicity cycle. On such a world the air would stink of excess Ozone by night and be lethal during the day when the sunlight was producing bulk quantities of fresh gas. As an additional note Ozone at high concentrations is both corrosive and explosive so bodies left out in the sun would dissolve and/or burn up in the Ozone bathed daylight hours. [Answer] I have found chlorine planets to satisfy such requirement. [Here is one](http://planetstar.wikia.com/wiki/Chlorine_planet). There are other possibilities involved: * sulfur dioxide if sulfuric acid replaces water * carbon dioxide: if the planet is too far out from its sun, it will need more greenhouse gases, such as CO2. An ecosystem in equilibrium must maintain a higher level, which may be harmful to humans. [Answer] I think carbon dioxide is your best bet as already described. If you want something more exotic then, Chlorine, Bromine or hydrogen cyanide might work but would need replenishing. Xeon is used as an aesthetic and would ultimately be fatal but high concentrations would be needed. Failing that have a look here: [highly toxic gases](https://en.wikipedia.org/wiki/List_of_highly_toxic_gases) [Answer] I am going to make the most cruel suggestion here. Have your world's crust have large amounts of surface uranium. How large? Let's say continental amounts. **But I asked for a gas, not a solid material!** Wait for it. Uranium naturally breaks into radon over time, which is a gas. [Wikipedia has some things to say about radon:](https://en.m.wikipedia.org/wiki/Radon) > > It is a radioactive, colorless, odorless, tasteless noble gas. It occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead; radon, itself, is a decay product of radium. > > > Also: > > As radon itself decays, it produces other radioactive elements called radon daughters (also known as radon progeny) or decay products. Unlike the gaseous radon itself, radon daughters are solids and stick to surfaces, such as dust particles in the air > > > Being a noble gas, radon is mostly non-reactive. So why is the presence of surface uranium required? Radon is short lived (it has a half life of 3.8 days), so it has to be replenished from a natural source. I like this idea because a simple gas mask or astronait suit will not be enough to protect a human in this environment. And anything you use to shield yourself from it will be covered in radioactive soot. As for how life could cope with it, just look for plant and animal populations around Chernobyl. Also for radiotrophic fungi that grow inside Chernobyl's reactor - they use melanine to extract energy from radiation in a process similar to photosynthesis. And these are life forms that evolved in our world - in a world that has always had high levels of radioactivity from the beginning, life would be much more resistant to it. ]
[Question] [ The Mind-Wolf is one of the [more dangerous](https://worldbuilding.stackexchange.com/questions/11252/how-to-catch-a-dream-thief) foes in my world. It can read minds, it can plant thoughts in the unwary, slowly warping senses until pushing the victim into the equivalent of a full blown psychotic episode, completely broken from reality. Given enough time, it can permanently alter/damage neural pathways, all of it via its long tendrils and frankly impressive capability to control fine electromagnetic fields for neural induction at what today's scientists would consider unachievable voxel densities. None of this is magic, unless by the Clarke definition of it as sufficiently advanced technology. However, the question remains. **Would an entity capable of such subtle, tailored thought-manipulation have to be conscious itself** (at a near- or over- human level), **or can it be a mere machine/lowly beast?** Edit: Let's define conscious as sentient in a Turing-capable way. [Answer] The Mind-Wolf would not need to "be conscious" to produce full blown psychosis. Consider that fairly simple drugs, produced from naturally occurring compounds, can produce all kinds of havoc in the mind, all the way to full-blown psychotic episodes ([See Wikipedia](https://en.wikipedia.org/wiki/Antimalarial_medication)). I lived in Malaria prone areas for most of the last 16 years, and know from first-hand experience how these common compounds can produce really horrid dreams. That can escalate to paranoia and psychosis. All your Mind-Wolf would have to do is to cause the same type of chemical changes in the brain that these drugs do, maybe amped up a bit. Also consider the way animals respond to people's emotions and moods. A dog does not have to have a "conscious" mind in order to respond to its owner being angry at something that has nothing to do with it. And also consider the mythic hypnotic capabilities of snakes, lulling their prey to mindlessness so they can kill them more easily. Then extrapolate that. Imagine a primitive, non-conscious mind that is able to respond to its victims moods, sensing their fear, disgust or other negative emotions that cause an agitated state or a disjointed state of mind. Imagine that your Mind-Wolf is also able to instinctively capture the thoughts or sensory perceptions that cause those negative states and is able to amplify them and feed them back, eventually rendering its victim helpless. The key would be that your Mind-Wolf would need to be able to sense what its prey is perceiving (sight, sound, touch, smell...) or thinking, even without understanding it, while also being able to sense what the effect on the prey's mind. Are the prey's reactions slowed down, thoughts disjointed? Chaos happens in our minds all the time. The Mind-Wolf would be able to sense that and enhance it, causing its prey to become helpless. It would not need to understand the thoughts and perceptions, just an instinctive feel that they are chaotic or disjointed. Mind you, most animals do a primitive very superficial form of this. When a blowfish inflates its body, it is engaging in a very mild form of thought control (all communication and interaction, at some level, is thought control), causing a perceived predator to become afraid and flee. Still, nothing about this reaction from the blowfish indicates that it is a conscious rather than instinctive reaction. We could get into discussions as to whether a dog (or a blowfish) has consciousness, but I think it is enough, for your question, to say that your Mind-Wolf does not need to have a more conscious mind than your run of the mill dog or wolf. [Answer] It depends on the type of thoughts it wants to plant. Our conscious, rational brain relies on associations to attach meaning to things. Such abstractions are learned and therefore differ from person to person. When a physicist, a biologist, and a poet look at a flower, it's unlikely that they'll represent it the same way in their minds. However, some thoughts build on instincts. Primal fears, hunger, sex drive, being tired or agitated, those function in a fairly uniform manner. Similarly, pain, sensor and motor functions, and so forth are simple enough that we know countless drugs to alter them. So, I'd expect that there is a huge jump in difficulty between manipulating instincts, vague feelings, and body functions versus causing structured and rationally meaningful thoughts. For example, if you want to make someone think of a tree, you have to find the nodes and connections representing a tree in this specific person's head. And those might not at all be similar to trees in your head. It's going to get very complicated. Then, it's important whether there is a conscious process between the manipulation and any intended effect. While "primitive" attacks like raising anxiety or making the target tired are straightforward, it is unreliable to trigger emotions to make someone do something specific. For example, the Mind-Wolf wants to keep someone out of a cave, so it plants fear. But the person happens to be afraid of open spaces and feel safe in caves! Suddenly, the person is eager to get inside, maybe even ready to fight the wolf to get inside! Without deep understanding of the target's thought process, such reactions can be quite unpredictable. *Consciousness* is a somewhat debated concept. If I take it as a synonym for self-awareness – which not everyone would agree to be the same thing – it's usually placed somewhere around the reflective ability required to pass the mirror test. If you want to plant a targeted, meaningful thought in a healthy, educated human, I'd say you'll end up needing more than that: you need to understand who the other person is and what is relevant in that person's world of thoughts. Doesn't seem like an easy task for some animalistic machine. **To sum it up**: * If the Mind-Wolf just needs to wreak havoc, it doesn't have to be smart. Mess with the person's stress level/Sympathetic nervous system. Amplify whatever thoughts correlate with anxiety and irritation. Or just induce random errors in the target's attention/working memory. It will deal a lot of damage. * If the Mind-Wolf wants to trigger an instinct, like making someone afraid, aroused, dizzy, careless, stunned, etc., that should be doable with reasonable effort too, and wouldn't be too different from the effects of certain drugs. I wouldn't want to rely on any results though, as people have different strategies of coping with impulses or feelings. * In order to place specific thoughts or ideas, that are meaningful with respect to reality, the Mind-Wolf would have to understand what the neural network of its target *means*. That requires detailed understanding and is probably extremely difficult. [Answer] No. You can have thought-implanting without sentience. There [exist real life organisms](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis) which do it. There are very simplistic animals (and even some fungi or bacteria) which can plant these thoughts into the minds of animals: * ants: "get up to a high place so the spores can be spread out optimally" * mice: "[go and get eaten by a cat](http://www.nature.com/news/parasite-makes-mice-lose-fear-of-cats-permanently-1.13777)" --- (Some clarification) > > (at a near- or over- human level) > > > I would guess you meant "**sentient**" rather than "conscious". Any animal can be conscious if they are not sleeping or otherwise knocked unconscious. [Answer] No, entirely not. The human mind is probably vulnerable to [replay attacks](https://en.wikipedia.org/wiki/Replay_attack). A monster does not need to understand the mind to manipulate it. Let's say the Mind-Wolf wants the human to do a task like "eat lunch". The Mind-Wolf does not need to understand what brain pattern maps to "eat lunch". Given that identical mental states map to identical behaviors, the Mind-Wolf simply needs to memorize what a human eating to lunch feels like. Then the Mind-Wolf simply has to splice the "eat lunch" thought pattern back into the human's head later on. [Answer] Maybe it's a "virus concious" and only concious when the host mind is thinking its thoughts for it. Consider that a biological virus has no metabolism or life processes, but co-ops a cell to act on its behalf. Maybe the wolf is the same way, acting as a computer virus in the mind, getting the host to suppliment its own small amount of processing power. Its own brain is a dumb animal alone and only knows enough to attack and find a host, as does any lizard or parasite. But once attached, it has *storage* for its own data it brings, but not the processing power to use it. It makes the host *think the wolf's thoughts for it*, which gives it access to the stored knowledge and the advanced planning capability of the host. And, in the case of a human host, the resulting mind becomes fully concious. [Answer] Yes, it would have to be conscious. If it wasn't how would it know what thoughts to implant in its prey? And even if the thoughts were simplistic (fear, anger, etc.) it would still need to have a higher level motivation to do this. The closest thing I can think of is the fungal infections that can attack ants. (Also, note: "The Last Of Us" videogame). But that just modifies the ant to enable the fungus to grow and spread, and quickly kills the ant host. [Answer] I think the question is: did it co-evolve with its target? If you find a random alien, the chances of being able to interact with its brain are none, period. But if you have had million of years to adapt, then there is nothing you can't do. Think of unicellular parasites controlling ants (planting the thought 'I want to go on top of a blade of grass' for instance) -despite having no brain. In this case, I think the real limit is that a non-conscious animal will maybe do something complex, *but it will only do the same thing every time*. If it evolved to have the victim, say, want to bake a cake and bring it to grandma on the other side of the forest, I think any animal could do it. But a human society would find a way to protect itself -maybe it would ban any form of cakes, so children don't even know what they are; then the wolf would lose all power, and possibly go extinct. A truly scary enemy is always only a conscious one who can outwit you. ]
[Question] [ This question is almost exactly like [Could plants develop intelligence](https://worldbuilding.stackexchange.com/questions/5097/could-plants-develop-intelligence), but now I wonder (how) could plant life develop **sentience**, to the point where it becomes as intelligent as humans? Is a brain necessary for sentience? These plants don't have to be completely photosynthetic, they can eat, but would it be possible for them to evolve to be able to form conscious thoughts and intelligence on the same level as humans? (These plants don't even have to be able to move around, they can be stuck in the ground.) Is it even possible for plants to become sentient? What physical structure would the plants require to become as intelligent as humans? What type of plant would most likely become sentient? Even though it's not classified as such, I'll consider fungi as a plant. [Answer] If it were ever to happen, I'd put my money on **mycelial networks**. While not technically plants -- mycelium is the underground form of fungi -- I think its structure has a lot of potential. *Scanning electron microscope images of human brain cells (left), and mushroom mycelium (right).* [![SEM human brain cells](https://i.stack.imgur.com/vIqHJm.jpg)](https://i.stack.imgur.com/vIqHJm.jpg)[![SEM mushroom mycelium](https://i.stack.imgur.com/02qtXm.jpg)](https://i.stack.imgur.com/02qtXm.jpg) The mycologist Paul Stamets [posits that fungi possess a kind of intelligence](http://discovermagazine.com/2013/julyaug/13-mushrooms-clean-up-oil-spills-nuclear-meltdowns-and-human-health): > > The analogies are striking. Brains and mycelia grow new connections, > or prune existing ones, in response to environmental stimuli. Both use > an array of chemical messengers to transmit signals throughout a > cellular web. (One part of a mycelium, for example, can order another > to send nutrients from hundreds of feet away.) The similar structures > of fungal and neural networks, Stamets believes, reflect the fact that > both systems evolved to do similar jobs — and do them with maximum > efficiency. > > > If you're going with the theory that **sentience emerges when a network of sufficient size & complexity is constructed with the proper topology**, I would keep an eye on the 3.4 square mile patch of *[Armillaria solidipes](https://en.wikipedia.org/wiki/Armillaria_solidipes)* in Oregon -- thought to be [one of the largest single organisms](https://en.wikipedia.org/wiki/Largest_organisms#Fungi) on the planet. [Answer] **Short Answer:** Perhaps, but probably not anywhere on Earth. **Long Answer:** In order to determine whether or not a plant could truly become *sentient*, we must first examine sentience within the human brain, according to the *Triune model*. This will involve breaking the brain into the parts: * The reptilian complex * The paleomammalian complex * The neomammalian complex *The reptilian complex* Consists of the brain stem and the base of the brain. It serves to carry out all of the brain's instinctual and system-sustenance functions. As far as emulation goes, this complex is relatively simple. Much of its job can be replicated by either an advanced, localized chemical-messaging system, or even by a decentralized neural network. Evolving such a complex isn't too unfeasible either. Many plants, such as the *Venus fly trap*, have already developed primitive versions of these systems. A plant would be most likely to evolve in this fashion if it had a set of one or more tasks (like closing a trap around a fly) which required the analysis of one or more input factors in order to produce one or more output factors. *The paleomammalian complex* Consists of the limbic system nodes housed mostly within the interior of the brain. This section is responsible for emotion and internal motivation relative to behaviors such as feeding, mating, and parenting. Emulating this section would get a little tricky, and would require the development of a central nervous system and a brain, though the brain itself would probably be about half the size of that of a mouse. ![Mouse Brain](https://i.stack.imgur.com/MWwTd.jpg) As for evolution, this complex would require a rather unique environment, in which traditional methods of mating (pollination) and/or obtaining resources (photosynthesis) are possible and yet not ideal for survival and continuation of the species. An example of this could be an area frequently shrouded by large, dense, slow-moving clouds, or where there is virtually no wind or pollinating insects present. *The neomammalian complex* Consists of the cerebral neocortex, and is the part of the brain responsible for complex thought including social interaction, language, and modeling of future events. Emulation of this portion of the brain cannot realistically be achieved without a centralized nervous system. At this point, the brain is at least 50% the size of that of a human brain. In addition, the overall sensory and motor/chemical input and output neural nodes within the plant would have to increase substantially. In order to evolve such a system, the plants would have to be forced by their environment to perform tasks together, like hunting, gathering, and/or competition over territory, in which communication can be extremely advantageous. If this were the case, there would need to be many of them, likely living in small tribes, in close proximity to each other. They would also need to possess resources, such as water, air (carbon dioxide), and/or sunlight, which would be obtained in a collective effort, and would have to be managed by each tribe as a whole. **Conclusion:** In order for a biological species to develop intelligence, that species must first be presented with an environment that mandates its development of an intelligence model in order for it to survive. Since the survival tactic utilized by plants relies only on the availability of light, water, and carbon dioxide, as well as a gust of wind or two to carry pollen from one plant to another, it would take a rather unique environment to trigger such a *deep-rooted* (ha ha) developmental process. [Answer] Why would a plant need advanced information processing? It only has any effect if it can *act on decisions*. Does this mean movement? Or deciding when to grow and in which direction? Given the fungi example, is there a benefit to higher-level *planning* in expending resources? That could lead to the development of a brain. Now among animals, consider a fruit fly. It has a nervous system and can make decisions based on input and provide a complex command and control system for flight. But that's nowhere near *intelligent*. Once an ecosystem exists where mostly-sessile autotrophs (plants as we know them) or *something* distinctly non-animal-like develops brains (to use the term loosely), what would then spur it on to increase its brainpower, and what would preclude it? Note that your fungi example has nothing to do with plants. Fungi are closer related to *us* than to any plant! A sponge however is an animal. I think the different/surprising thing you wonder about has to do with "well-defined solid bodies" and "rapid and active movement through the environment". You could invent a category of lifeform that defies animalness as we understand it, and develops brains. [Answer] **I'd like to think loudly about a possible environment leading to Mycelium developing the need for further planning:** First of all, after what was wrote it seems to be clear, that it is only possible in combination/"communication" with certain other creatures (like plants or other species of mycelia). So which species could encourage the developement of communication? * I read somewhere that some species of mycelia take over existing colonies by changing the genetic material and some fighting each other using toxines etc. So there seems to be a possibility of communication. * There is already a kind of communication with the roots of plants, sometimes even transport of messages about dangers to other plantspecies. But that doesn't seem to be enough. I was thinking that a scenario where a certain plant A evolves or comes into the area of out mycelium which as a single individual has a profit for the mycelium as their roots are producing a substance against enemys of the mycelium and maybe even providing some nourishment. But as soon as it becomes a colony of three or more individuals at one spot that substance becomes poisonous to the mycelium and it suffers. At the same time that plant A would be slightly benefitting of growing in a colony. Wouldn't this scenario encourage mycelia which are able to plan strategies of keeping this individual plant A while preventing other seedlings of it around (maybe by providing special growth factors for a competing plant B which is covering the floor around and making it impossible for plant A seedlings to develop)? In the same time there would be an interest for the mycelium to plan another place where an indicidual of plant A could grow. **Second approach** Given a really large mycelium over several hundred acres which is able to invade the genome of other mycelia to take control and in the same time producing a chance for minor mutations or integration of that original genome. Now if there was a neophyte or neozoon (animal or plant which is not from this ecosystem) which regularly spreads over a place like several hundred square meters until it collapses leaving back a poisonous ground where nothing else can survive including the mycelium until that poison decayed. Maybe that could encourage the devolopment of countermeasures. Either of fighting that invader or of adapting and including own DNA in that plant to make it compatible. Given a long time and regular occurance of different invaders this might result in a Mycelium which is altering its own environment including other species to fit its own need. Maybe that wouldn't need sapience or self-awareness but in the long run considering more and more species it might develop into something like the Avatar-Network - no? [Answer] I think you first need to answer *why* they would need intelligence. Plants aren't intelligent (as far as we know) because they don't need to be intelligent. They are brainless and wildly successful. What does intelligence get them? The first hurdle then is mobility. Mobility leads to options and to exploit, or choose the best options, well that requires an ability to think logically, memory and analytical skills are a plus as well. The second hurdle is going to be socialization. Several studies indicate that social animals are more intelligent than solitary animals. Successfully navigating the pitfalls of group politics requires an agile mind. Keeping your group alive requires planning, communication and an understanding of time (to take advantage of seasonal foods/migration patterns. If you want intelligent plants then they're most likely going to be social, if not like humans then perhaps like whales or dolphins. Finally there is tool use. This might not actually be a requirement, but it is perhaps the most obvious indicator of sentience. Dolphins might be incredibly smart but they can't use a screwdriver so there is no obvious indicator of the intelligence. The same for your plants. Of course this could be a story driving element, the slow discovery that they aren't just plants but actually intelligent beings. Neat premise, good luck! [Answer] Sheraff said this on the other question, but brains are a HUGE waste of oxygen. Plants have an extremely low metabolism, so they would need a different way of becoming sentient or being extremely close to the sun. There was once a theory that certain dinosaurs had multiple brains, and the secondary ones were for activities that required less thinking. Maybe this would be useful for ordinary activities and the primary brain would normally be dormant. ]
[Question] [ In popular science fiction, we see habitable Earth-like planets with visible, Saturn-like rings. In reality, such rings exist only on gas giants, a category where we can find Saturn. Is it really possible for a planet similar in gravity to Earth to have the kind of gravity needed to create these rings? If no, then what kind of changes would I do to make sure Earth does have them? [Answer] We kind of already do: [![enter image description here](https://i.stack.imgur.com/KNzC6.jpg)](https://i.stack.imgur.com/KNzC6.jpg) This is a false-scale image of all objects in orbit around the Earth that NASA/RSA/EASA jointly monitor. You can clearly see the outer ring of GEO objects. Most of these objects are manmade, and most of those are space junk; decommissioned satellites and their debris, pieces of launch vehicles we had to accelerate fast enough to get into a stable orbit, etc. There are thousands more manmade pieces of debris that NASA doesn't keep an eye on because they're too small to pose a re-entry hazard and aren't in a conflicting orbit with any valuable satellites. There was, at one point, an image from a survey probe that caught a beautiful "goodbye" picture of Earth with the sun perfectly aligned to glint off the debris ring around Earth, but I can't find it in the midst of all the "artist's impressions" and enhanced images. In addition to debris, there's space dust and meteoroids that have been drawn into a stable orbit around Earth, too small to track, but definitely still a hazard; this is what one of those micrometeorites did to the Challenger on STS-7: [![enter image description here](https://i.stack.imgur.com/pOgxS.jpg)](https://i.stack.imgur.com/pOgxS.jpg) As far as why we don't have more, it's mainly chance. A long-term stable orbit around a planet of Earth's size is a fairly tricky thing to achieve, especially without being able to make adjustments. The rings around the gas giants are much more prominent for three reasons: * They're more massive, so as they formed, they carved wider swaths out of the accretion disk as they "cleared the neighborhood" of their orbit. In addition to its size (95Me) and its rings, Saturn has 13 objects large and round enough to call "moons" (at least 50km diameter), plus 40 additional named orbiting bodies and another 9 objects with a confirmed size and orbit. * They're further out than Earth, so they get the first shot at capturing "new" stuff that de-orbits from the Kuiper belt and Oort cloud out around and beyond Pluto. * Because of the relative importance of the mass term and the distance term in gravitational force equations, more massive objects have a wider range of stable orbits, thus random object incursion doesn't have to be quite so precise as it would around Earth. In addition, what you're seeing around the gas giants is survivor bias; the gas giants, being, well, gas and giants, are much more tolerant of outright impacts, so we don't really see their effects unless we happen to be watching (like when the remains of Shumacher-Levy 9 hit Jupiter). The earth, in its first few million years of existence as a ball of cooling magma, was nearly destroyed by a mass that would become the moon. This chance encounter turned out to be advantageous for the planet, as it gained a sizable shield which has protected the planet from countless impacts over the years by taking the hits itself. [Answer] Yes, Earth is large enough to have rings. What you need would be an object orbiting close to the planet like a small moon. It needs to be inside the [Roche limit](https://en.wikipedia.org/wiki/Roche_limit), where the object will start to disintegrate because of the tidal forces. [Answer] Earth DID have a ring! BUT, it slowly collapsed in on itself by the force of its own gravity. 4.527–4.533 Billion years ago Theia, a planet with a size similar to Mars, smashed into Earth, and the remains collected in orbit around earth. That is why Luna is comprised partially of mater originating from Earth's crust. (Some people used to call Theia "Orpheus") Theia originally orbited around Earth at the L4-L5 points. As it gained mass it was slowly knocked loose from orbit by Venus, and caused it to strike Earth, possibly merging the two planetary cores, which is why Earth's core is much larger than the cores of similarly sized planets. In around a century (less than two) gravity collected all the larger portions together into Luna. Within the next Million years, the crust had formed. Over the next 300 million years (3.9B–4.1B) meteor storms and comets ripped the surface back apart, temporarily creating ANOTHER small ring. It settled back when the "weather" calmed down again, until about 108 million years ago when the last great asteroid impact formed the Tycho crater. [Answer] Solid bodies disintegrate after reaching the Roche Limit. However, Earth´s Roche Limit is a little bit inside the atmosphere so any body that is destroyed by tidal forces inside that limit will also fall by loss of potential gravitational energy because of any interaction between air particles and molecules, this is why Earth doesn't have rings. If we have a smaller, less massive and thinner atmosphere it could be possible for Earth to have rings. ]
[Question] [ So you are rebel, your name is Norn, and you are hidden away in a lovely forest swarming with all kinds of little critters, in the middle kingdom where the king and his formidable military are hunting you and would like nothing more than to decapitate you and every one of your rebel buddies...the king is a bit of a jerk. You are unfortunately ill prepared to face the king and his armies, they are well armed and armored while at best you and your rebel friends are wearing a bit of leather here and there and metal weapons are few and far between. Your rebel group is brave but hasn't been terribly effective in achieving the long term goal of removing the king's butt from his cushy throne, and several generations of rebels have continued living in the forest (we are attempting to remove despot king #4 here...really slow rebels). Word from informants in the capital has reached you and it is bad news. The King's army is marching on the forest intent on eliminating your little band of merry men (TM). The army will outnumber the rebels by about 5 to 1, it will be a mix of unarmored archers, knights on foot (as heavy as possible armor), and lightly armored infantry. The kings forces number roughly 5000, and contain 500 archers, 500 knights and the remainder are mixed light infantry. Looking around at what resources are available to you it comes to your attention that the forest creatures are familiar and friendly with the rebels, many of whom keep them as pets and companions. Maybe, just maybe, you could utilize the creatures in battle. Certainly the pets will stay with their masters, but what of the others that may be willing to aid you? **Limitations** * There is no magic in this world, so no charming the creatures to attack or anything * No *suicide* critters, they are your friends after all, you wouldn't send your friends charging into a line of pikes I would hope (if you would you are a jerk...and possibly this king) * Need to be used in battle side by side with human rebels, The animals shouldn't be a sacrificial first wave. * Limited to what these creatures can actually be trained to do (falconry for example), though I will allow a little wiggle room here if it makes it more interesting. You are limited to the use of the following creatures (with quantities) * Bear with grizzly size and weight (1) * Bobcats/cougars (4) * Wolves (2 dozen) * Falcons/eagles (1 dozen) * Owls (1 dozen) * Foxes (3 dozen) * Raccoon (4 dozen) * Rabbits (no limit) * Squirrels (no limit) * Hedgehogs, porcupines, ferrets, weasels, skunks etc (no limit) * Smaller birds: ravens, jays, robins, woodpeckers (no limit) *If there are other animals you would like considered for this effort ask in the comments* You may use as many or as few of the animals listed in your answer as you would like. Answers should take into account the real world abilities of the various animals. Animals may be armed/armored if they are capable of wearing/utilizing such items How the animals can help counter the specific troop types should be included. [Answer] **Guerrilla tactics are the only approach you can use** or you're all going to die horribly. Attacking or defending against a 4x superior numbers is just suicide. Don't do it. You will need to attack them sideways. **How I learned to stop worrying and love psych warfare** In terms of warfare, "magic" = "psych warfare". This can be execute any number of ways. Small animals can be trained to pull off what appears to be magic such as making tools disappear or strange noises as the king's troops move through the woods. Doing what you can to give the appearance of a haunted place saps morale so even if your rebels do encounter enemy troops their resolve will be lower. **Rebel Tactics** * Maintain a mobile camp so that the king can't ever find you. Set up false camps as bait for ambushes. * Long range arrow attacks from concealed positions with only a small number of your archers. These are harassment or high profile target attacks only. Remember, open confrontation isn't an option. * Use Vietnam era booby traps to kill/wound/injure/maim enemy troops. You don't have to kill many of them to instill a healthy sense of fear. If patrols and scouts don't come back, or are found days later in the bottom of spike pits, the morale of the king's troops will sink very quickly. It will take a lot of work for the king to get his troops to go searching for you. * The trade-off is that if they catch of your merry band, they will torture you horribly then kill you, maybe....but perhaps that was going to happen anyway. * Attack any resupply efforts. * Where appropriate, fire attacks to destroy the enemy camp. * Spread rumors of giant bears who eyes burn like coals or how the forest is haunted because of some ugly death. Tailor the rumors to the superstitions of the king and his troops. **Uses of Animal Friends** Bears - Attack the enemy horses or just make them perpetually nervous. Work in concert with foxes to avoid retaliation by any hunting dogs that the king may have brought along. Foxes - Make sure that no one sleeps. Have them encircle the camp and just [howl at random intervals](https://www.youtube.com/watch?v=KJmkM346058) through out the night. Eagles/falcons - Scouts. Raptors won't be able to tell you how many troops there are but they should be able to indicate enemy positions. Hedgehogs, porcupines, ferrets, weasels etc - Incredibly difficult to find if they don't want to be found. They all love to chew on things so they can be used for destruction of leather, rope, cloth or wood. If the enemy's kit is falling apart, their combat effectiveness goes way down. Porcupines love wood. They eat it all the time. Since most of the enemy's carts will be made from wood, let the porcupines eat it. They can also just back into the enemy's horses to make them lame. Ravens, jays, robins, woodpeckers - general harassment where possible. Many of these birds aren't aggressive so their utility will likely be limited to observational roles. Woodpeckers might help the porcupines with destroying enemy assets. **Oh Gross...** The king and his army can't attack you if they have explosive diarrhea or [cholera](http://www.who.int/mediacentre/factsheets/fs107/en/). (Also, without proper rehydration, cholera can kill in hours.) Enlist the aide of your *bacterial* friends by having all the animal friends plus the entire rebel band poop in the water supply upstream from the king's camp. Mice and rats can be let loose on the enemy's food supply to contaminate it with feces or urine. (No training required, mice and rats are always hungry and don't particularly mind where they poop.) Skunks. Oh my, skunks. Skunks are the ideal area denial weapon. There is nothing smellier in the world that skunk musk. Train them to spray enemy combatants or enemy food supplies. [Answer] **Step 1**: Re-center yourself. You've been engaging in a rebel campaign to unseat the king. The king is now striking back. This is the time to re-evaluate your priorities. Even [mercenaries](http://www.schlockmercenary.com/2000-08-04) have to re-evaluate their priorities from time to time: > > Priority number one: get paid. > > Priority number two: Live long enough to spend your money. > > - Tagon, *Schlock Mercenary* > > > The king has now made it his focus to remove you from existence. How badly do you want to try to depose him? Time to refocus. Your goal is to survive the onslaught while retaining that essential essence that made you devoted to your rebel cause in the first place. You will need to engage in vastly asymmetric warfare. Your opponent has overwhelming physical might. You will need to win the battle on the mental front, encouraging him to decide to spend his resources elsewhere. Once he is no longer focused on your eradication, you can resume the traditional "short live the king" mentality. **Step 2**: Patience. This is the hard part. Your opponent has overwhelming force and wants a decisive victory. You may want a decisive victory too, but you're not going to get it. That's why we invented swords and armor... to make sure the other guy doesn't get a decisive victory. This is going to be a long fight. You need to make sure that every resource you spend is spent worthwhile. The best approach to this is to Stop Worrying and Learn to Love the Bomb, I mean... sorry... wrong storyline for a moment... where was I. The best approach is to turn the fight into the kind of fight where you fight them simply by living. That way, no matter how the fight goes, you went on living a good life. This is going to involve some creativity. You are going to have to find ways to make the presence of the king's men a beneficial part of your life, despite all their pointy sharp things. This will take time. An army is usually not structured to make the enemy's life cushy. You're going to have to calmly and patiently explore their structure. There wont be a one-size-fits-all solution for you, or the army would stop it. You have to look at how you and the enemy army will interact, and find some details about *that* army and about *your* men which let you live. It's all up to your imagination here. **Step 3a:** Vanish Don't worry, I wont leave you hanging with some whims of imagination there. While there is no one-size-fits-all solution, there are directions worth looking in. The most important step is to live long enough to get paid... or...well... whatever you're rebeling for. Your opponent is designed to build a net to capture a band of merry men. You need to cease to fit their mental image of what a band of merry men must look like. You need to become so completely one with nature that, when they send out scouts to draw the net around your band, you can simply flow through the net like water through a sieve. There are some tricks here. This is war after all. I would quickly train any animals like foxes, falcons, and wolves to go after the dogs the army brings along. Your human smell is your biggest weakness. Dogs can sniff it out from a mile away. However, trained dogs are not cheap. It will strain their resources if you can pick them off one by one. You may have to be creative here, like in every step. You may have to structure your own scent trail to draw dogs into kill zones. In all, you want the battle of the nose to work in your favor. Once the dogs are neutralized, you are just fighting men. Men are not as perceptive as dogs, so it will be much easier to vanish. **Step 3b:** Recon. Train your animals to give you information about where the enemies are. The birds are already trained. They're going to give you tons of information about where they are. While you're at it, return to step 3a and train yourself and the birds so that the birds don't give you away. Become one with nature. You are fighting the mental game. You cannot fight the mental game without insight into where the enemy's physical force is. Wherever their physical force is, that's where you need to not be. **Step 3c**: Supply lines If you retreat backwards into the woods, you will force the army to develop supply lines. These are known to be a great weakness of armies. If they are sparse enough to live off of the land, they may be picked off one by one. That's not the army's style, they're more likely to draw a supply line from the kingdom to ensure they have supplies of men, food, and possibly more dogs (you'll have to keep picking them off). Supply lines are great, because they're ripe with things you want, like swords, food, and more swords (I mean food, swords, and more food!). Best yet, they are long and remarkably hard to defend against unless you know where the enemy is (you did remember to vanish, right?). Send in the racoons to wreck havoc on their supplies. Maybe you can even teach the greedy bastards to bring back some of the food they steal! This is where the cost mounts for the king. Supplying an army is not cheap. Doing so with losses along the supply lines is even more expensive. This is where you get to send your mental message: we are less bothersome as a band of rebel merry men than as your mortal enemy. If you stop treating us as a mortal enemy, we'll go back to just being pesky and ineffectively trying to depose you. Convince him it's too expensive to crush you, and he'll eventually have to back out. Or, if he's really a jerk, he'll raise taxes, but hey look... easy way to piss off a kingdom enough to remove his cushy butt from the throne (or was that "butt from his cushy throne?" Those adjectives are easy to misplace). Either way, the war will move in your favor. **Step 4**: Bear. Bears are scary. Bears are mean, nasty, and capable of gutting a man like a fish by accident if they hug him too hard. Did I mention they are scary? Did I mention they are even scarier when you are an isolated army with inadequate supply lines, worn out weapons, and a really creepy spooky forest full of violent trained animals, at night? Bear. If you do a really good job of training the bear, you can even convince it to leave a few men behind to tell stories at the tavern of just how huge the bear was with glowing red eyes and smoke coming from his mouth. Then you can go back to rebeling to your hearts content. The king may send an army to attack a band of merry men, but a mythical demon-bear-beast worthy of a a place in Norse mythology? Fat chance. ]
[Question] [ I have a fictional character in 1870 who is a marksman of superhuman ability; basically, he doesn't need a sniper rifle with a telescopic sight, he *is* a sniper with a telescopic sight, and can get the maximum physically possible accuracy from any weapon. Looking at the weapons available at the time, this one seems representative: <https://en.wikipedia.org/wiki/Snider%E2%80%93Enfield> > > Effective firing range 600 yd (550 m) > > > > > Maximum firing range 2,000 yd (1,800 m) > > > I understand these two specifications to be, respectively, the range at which you can hit a man-sized target with reasonable probability, and the maximum distance the bullet will travel and still retain a lethal amount of kinetic energy. I'm trying to figure out what would be the effective range of this weapon in the hands of a superhuman marksman. It seems to me the best way to approach this is to ask, what is the limiting factor on the effective range? Is it the accuracy of a human marksman? Is it random environmental factors like the wind, that a superhuman marksman could conceivably compensate for? Is it some 'random per unit, but fixed for that unit' variation in the rifle itself, that the marksman could conceivably learn to compensate for? Is it inherent randomness in the system, impossible to compensate for, that will limit the effective range to 600 yards regardless of the shooter? [Answer] # Accuracy variables: There are a lot of variables that are tricky to control for your super-sniper, mostly the quality of the industrial processes at the time. If he maintains his own gun-smithy, he may minimize but not eliminate these variables. The problem is that this kind of accuracy was simply not expected in the period, so manufacturing standards didn't generally measure up. * **Powder:** The powder of these weapons is [gun powder](https://www.britannica.com/technology/gunpowder), which is variable in manufacturing quality, consistency, and storage. It leaves a residue in the gun, requiring frequent cleaning. The discharge leaves smoke in the air that obscures vision and interferes with subsequent shots. It also reveals one's position. [Smokeless powder](https://en.wikipedia.org/wiki/Smokeless_powder) was invented in 1884, but is within the capability of people at this time to manufacture if the basic technique was known. In the novel [The Guns of the South](https://en.wikipedia.org/wiki/The_Guns_of_the_South), time travelers introduce the idea of nitroglycerine to a Southern chemist, who then intuits gun cotton (nitrocellulose) smokeless powder. * **Primers**: [Primers](https://en.wikipedia.org/wiki/Primer_(firearms)) were manufactured products, percussion caps, and the manufacturing quality was somewhat variable. Reliability is better than powder in pans, but is still not perfect. Even modern-manufactured percussion caps for muzzle-loading rifles are of variable quality and make such weapons somewhat unreliable. * **Bullets**: Bullets by this period were mass-manufactured, but slight imperfections could introduce variation in the best ammunition. Rifling helps to eliminate some of this variation (imperfections in a spinning projectile are "averaged out" in centrifugation) and weren't overly significant for the average shooter. But for your guy? It could be a real problem. The bullets are frequently sub-sonic for most of their flight (although the muzzle velocities could be supersonic), and big. While [accurate subsonic bullets](https://techlinkcenter.org/technologies/subsonic-bullet-with-optimized-nose-cone-and-boattail-for-improved-ballistics/3ec2ac5b-9331-4704-8547-c894c526f2e7) can be made, it would be tricky to justify given the exotic metals and designs involved. [Copper-jacketed bullets](https://en.wikipedia.org/wiki/Full_metal_jacket_(ammunition)) (improving velocity, preventing deformation, protecting barrels and reducing lead residue in the gun) aren't invented until 1882. The [copper electroplating](https://www.dorsetware.com/a-brief-history-of-electroplating/#:%7E:text=Electroplating%20was%20invented%20in%201805,to%20become%20attached%20to%20it.) process, however, was invented in 1840 so copper jacketed rounds could technically be done in this period (but the process is nasty and involves cyanide). # **Range**: So we get to range. Most modern [muzzle-loading riles](https://www.realtree.com/brow-tines-and-backstrap/5-things-to-know-about-muzzleloader-accuracy) with scopes are not reliably accurate beyond 200 yards. Although you specified a breech-loader, the overall design tech is comparable for accuracy. I might suggest the [Sharps rifle](https://en.wikipedia.org/wiki/Sharps_rifle) family of weapons for range and accuracy in a breech loader. I suggest the movie [Quigley Down Under](https://en.wikipedia.org/wiki/Quigley_Down_Under) might correspond very well to your super-shooter (although this is a scoped rifle). The effective range of a sharps rifle is 1000 yards (the movie claims 900-1200, but that's 1890, using an 1874 version of the gun), and this is a likely outer limit for your shooter. The longest documented shot with such a rifle is [1538 yards](https://www.imdb.com/title/tt0102744/trivia/). For a super-shooter, the 600-1000 yard range might be realistic. For 600 yards, most of this "effective range" involved a thousand guys shooting at another thousand guys and killing more by mass of fire. At the 2000 yard range, the relatively large size and low velocities of these bullets mean your opponents might get hit, but possibly not significantly injured. Little effort in this time is made to make bullets terribly aerodynamic. So to get much beyond 600 yards, your marksman probably needs to be a gun smith, making his own custom powder, casting bullets by hand, prepping and making his own powders, possibly buying specialty percussion caps made for the royalty of Europe. Even then, the guns of this time are unpredictable. [Answer] **Pretty poor** First, let me endorse the answer by DWKraus, which does a good job of enumerating many of the variables that will contribute to inaccuracy. There are a few additional points, however, that are too long for a comment on that answer: Looking through various black powder shooters' forums and the comments about the Snider Enfield, a number of shooters are complaining of the difficulty of achieving even a halfway reasonable grouping. (Put "benchrest grouping with Snider Enfield" into your search engine and see what comes out - I went with "benchrest" to simulate a super-shooter with a perfectly steady shooting position.) * One shooter was complaining of shooting 8-10" groups at 50 yards, another of 19" groups at 40 yards! The posters were experienced shooters, meaning that the rifles were wildly inaccurate with what was expected to be the correct combination of projectile and powder quantity. These results mean that even a skilled shooter with a Snider Enfield and sub-optimised ammunition will achieve worse accuracy than a mediocre or average archer! * Another shooter was fairly happy with their benchrest grouping at 50 yards, as seen in the image [here](https://www.tapatalk.com/groups/britishmilitariaforums/snider-accuracy-t802-s220.html). (For those wondering about the size of the target who haven't scrolled down in the comments thread, the "black" is 200 mm across, which shows how big the holes are.) This accuracy is adequate, but really poor compared to even an average beginning rifleman with a modern rifle. * It appears from the discussion that accuracy degrades significantly after every shot without cleaning the rifle due to the unpredictable consequences of residue from previous shots. So while it may be possible to shoot reasonably quickly with a breech-loading black-powder rifle, shooting *accurately* will be slow because it needs to be cleaned after every shot. Even a superhuman marksman should have a set of rifles and equivalent number of gun bearers to quickly clean them between shots. At this point, the accuracy starts to come down to the exact abilities of the superhuman sniper: * I am assuming inhumanly perfect muscular control and superhuman visual acuity, in other words every shot is as if from a benchrest and using a telescopic sight (if required). Looking at the linked image and assuming they can halve the grouping size with perfectly tuned ammunition (that is, all the variables DWKraus listed) and impeccable trigger release, call it a 6 cm grouping at 50 m with increase in group size proportional to the range. * Superior vision and instincts allow for the wind variation at ground level to be identified and perfectly allowed for. Moderately believable, this lets the 50 m grouping be applied against stationary targets out to the listed "effective" range of 550 m, although at this range the ESA (expected scoring area) is 66 cm, which is wider than a typical man-sized target. Without this ability, the ESA will expand exponentially (not linearly) with range in windy conditions. * Foresight (the ability to see into the future, not the sticky-up bit of metal near the muzzle) is required in order to hit *unpredictably* moving targets more than about 200 m away. If a target is stationary or moving predictably then no superhuman abilities are required, which is how snipers and hunters make long range shots in real life. Note that the Snider Enfield only has a muzzle velocity of 381 m/s (depending on the exact powder and projectile combination), so with air resistance it will be 2+ seconds for the round to get out to the effective range of 550 m - a lot can happen in that time. * "Shooting omniscience" is required for shooting at longer ranges or achieving tighter groupings with the equipment available. The shooter needs to know exactly how each propellant charge is going to perform *and* how each microscopic piece of matter in the barrel is going to affect the progress of the round *and* the vectors of all the masses of air in the trajectory that the bullet is going to pass through (noting that the air many metres above ground level can be moving at a different speed) *and* how the bullet will behave aerodynamically at each point in its trajectory. (This is along with all the muscular control and perfect vision mentioned previously.) Note that if the superhuman marksman has this ability then he shouldn't be messing around with shooting things, he can throw dice with perfect knowledge of how they will land and make a fortune gambling instead. In summary - ignoring foresight and omniscience, I would consider it believable for a superhuman marksman with perfect 1870 equipment to make headshots every time out to 150 metres on stationary / predictably moving targets and reliable chest shots out to 300-400 metres. He may get lucky at longer ranges but he may not - fortunately for him, he can claim what he likes and those without a telescope or superhuman vision will be unable to tell what happened at long ranges. If you give him equipment better than the Snider Enfield (eg the Sharps that DWKraus suggests) then modify ranges accordingly. [Answer] **To get those long ranges your shooter will be shooting up at an angle.** AKA "volley fire". The Enfield had sights to facilitate this. [![shooting at an angle](https://i.stack.imgur.com/wQzgZ.png)](https://i.stack.imgur.com/wQzgZ.png) <https://www.youtube.com/watch?v=CWOw9Q6bovs> But the thing that surprised me - really not much of an angle! This shooter states that his gun was at 11 degrees and that looks right to me. The target is 3000 yards away. I wondered - suppose you elevated the barrel to 44 degrees. That would take the maximum height of the bullet 4x higher than it was at 11 degrees. Let us ignore wind resistance and consider only gravity. If gravity is what stops the bullet by causing it to run into the ground (and in the video the puff of dust suggests it was still moving fast when it hit) would the bullet travel even farther? I think yes - my triangles say 528 more yards for a distance of 3528 yards. That is just over 2 miles. [![triangles](https://i.stack.imgur.com/M4EgJ.png)](https://i.stack.imgur.com/M4EgJ.png) In any case, your shooter at maximum range would appear to be shooting at something in the sky. Which he is - the top of the parabola he needs to make with the bullet between himself and the far distant target. --- An interesting thing about the video is you can calculate the speed of the bullet, roughly. It is 10 second in each shot from shot to puff of dust. That means an average of 300 yards/second or 900 feet / second. Published speed of an Enfield bullet is 1300 feet / second. Assume 1300 at muzzle and average speed of 900. How slow is the bullet at the end? Math (or maths if an Australian is doing them) 1300 + x = 900 \* 2; x = 500 feet per second at the end of the flight. Not as fast as a pistol bullet at 50 yards (700-800 fps) but I bet it would still put your eye out. And this guy is a supernaturally good shot. [Answer] **By 1870, effective range of sharpshooting was about 1000 yards** This was pretty much as good as early rifles like [Sharps rifle](https://en.wikipedia.org/wiki/Sharps_rifle) or [Whitworth rifle](https://en.wikipedia.org/wiki/Whitworth_rifle) could do reliably. General [John Sedgwick](https://en.wikipedia.org/wiki/John_Sedgwick#Death) was killed from about 1000 yards distance during American Civil war, but beyond that distance rifles of that era just couldn't be accurate enough. However, in 1870s there was significant improvement in both rifle and cartridge design, which pushed sharpshooting limits up to about 1 mile (1609 meters). ]
[Question] [ What are the biggest and the smallest possible sizes for a celestial body such that a human (in a not-too-advanced spacesuit if needed) could walk on like on Earth? More precisely, the celestial body should have the following requirements: * Roughly spherical shape - it shouldn't have anything non spherically symmetric to help its structure, such as significant rotation combined with a cylindrical or toroidal shape * Stable over a typical human lifespan * A surface which can safely support a standing human indefinitely * Atmospheric pressure (if any) and temperature manageable by early 21st century spacesuits * Earth's gravity at the surface * No lethal radiation Size is defined as the radius at the surface to be walked on. Formation of the celestial body is irrelevant - it just has to be able to exist satisfying the above requirements. Also, it can be composed out of anything known and anything that is seriously being hypothesized, so even the exotic stuff is fine as long as it is described in peer-reviewed papers and considered plausible to exist. First thing one could think of is making a ball made out of heavy elements for the small body (maybe surrounding it with a thin insulating layer if something radioactive would be used) and a ball made out of light but solid elements for the big one. However, this wouldn't cover a wide range of sizes. It would be interesting to see something roughly comparable to the asteroids from *The Little Prince* for the small body and something comparable to Jupiter or maybe even a Dyson sphere for the big body. Celestial bodies of these sizes sizes certainly do exist, but they don't satisfy the "walkability" requirements (e.g. neutron stars are very small, but also very massive, resulting in an extreme surface gravity among other issues). Maybe a bit of something exotic could be combined with something more mundane in the composition to allow for a wider range of sizes of walkable celestial bodies. [Answer] **Smallest Possible:** The highest density you can get with a naturally forming planet would be from one that forms in an environment that averages about 4600-5000°C. This will boil away everything else leaving just a molten mass of Tungsten, Osmium, Rhenium, and Tantalum. If something were to then happen that pulls or pushes the planet farther away from the heat source, you would be left with a round solid heavy metal world with a density of somewhere between 16.65-22.59 g/cm³ depending on the ratios of these 4 remaining elements. Since you won't get a purely Osmium world this way, your actual density cap is probably going to be somewhere around 20 g/cm³. (Technically a purely Rhenium planet could be 21 g/cm³ but its boiling point is so close to the less dense Tungsten that boiling off Tungsten without also losing your Rhenium is unfeasible). This would give you a radius of about 1750km If your planet is artificially formed from natural elements, you could make it out of pure Osmium for a maximum density of 22.59 g/cm³ and a radius of 1550km. This would not happen in nature because of boiling points and co-genesis of these elements from the same sorts of astrological events. For a an artificial structure that relies on purely theoretical science, you could build a shell around a primordial black hole (if they exist), but you have to make sure it is not so small that it would just melt from the black hole's hawking radiation. For this I would suggest you use a black hole that is ~6e13kg at a radius of about 20m. Now, something this small just containing a black hole of this size would probably just melt... unless you are doing something useful with all of that heat. With some clever engineering you can treat this "world" as a tiny power plant. At a power output of 100KW, this black hole is 10,000 times weaker than the average nuclear power plant which requires about 2.6million m² of land area meaning this power plant only needs about 260m². Since your tiny world has about 5027m² of surface, you have plenty of room for both the power plant and any additional stuff you may need to expend or transfer the energy off world and radiate off the unused heat. With cleaver engineering, you could probably even go a few meters smaller, but every meter you contract, the smaller you need to make the black hole and the hotter it gets, and the less room you have for your reactor... this means the issue of heat goes up exponentially VERY quickly at a smaller scale. **Biggest possible:** The biggest possible natural world is really hard to solve for because it is so hard to predict how loosely elements can pack under unknown circumstances. For example, Hyperion is a moon with what appears to have a rocky crust and maybe a highly porous icy core, but we don't really understand it that well. All we know for sure is that it has a density of only 0.5 g/cm³. Since we can't explain how it was formed or why its density is so low, we cannot extrapolate for sure if this phenomenon could apply to larger worlds. But if we work off of the assumption that it might, we could get a radius of about 70,000km. For an artificial solution, the lightest known solid material that that can survive in 1G is a substance called graphene aerogel. With a density of .00016 g/cm³ you could have a radius of about 218,000,000km meaning you could make a solid planet just a bit larger than the orbit of the Earth around the sun with one surface G. Now keep in mind that this math assumes a solid, homogeneous, aerogel structure; so, engineering limitations might force you to use a denser aerogel as you get to the core to compensate for pressure, but as an engineered structure, you also don't have to make it perfectly solid either; so, after all engineering variables are solved for, you might have an aerogel lattice structure or hallowed out structure over a billion kilometers across or you might be forced to make something much smaller. This is really hard to predict for certain without working out every possible engineering solution to the problem in detail, but either way; something on the dyson sphere scale certainly seems possible. *All calculations are approximations based off of these calculators:* * *<https://planetcalc.com/1758/>* * *<https://www.ericjamesstone.com/blog/home/gravity-calculator-for-astronomical-bodies-based-on-radius-and-density/>* * *<https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator>* [Answer] **Small Body: About 100km (Actually 1000km) Radius.** The problem with small bodies is (a) Limits on matter density and (b) tidal forces. For example more gravity at your feet than head is a recipe for a bad time. Let's do some rough calculations to see how small the body needs to be for double gravity at the feet. Say the planet has radius is $r$ metres and mass $M$ kg, the person is $2m$ tall and has mass $m$ kg. The gravity $F\_2$ at their head is half the gravity $F\_1$ at their feet. Then for the gravitational constant $G \simeq 5 \times 10^{-11}$ we have $$F\_1 = \frac{GMm}{r^2} \qquad F\_2 = \frac{GMm}{(r+2)^2} = \frac{F\_1}{2}$$ Solve to see $r = \frac{2}{\sqrt 2-1} \simeq 5$ metres. We also want the force at the feet to be the same as Earth which is about $10$. So we solve $F\_1 =10m$ to get $$F\_1 =10m \implies \frac{GM}{25} =10 \implies M = \frac{2}{5G} \simeq \frac{2 }{25} 10^{11}$$ So we need that much mass in a 5 metre ball. So what material is dense enough for that? Well the mass is $\rho (4/3) \pi r^3 \simeq 4\rho r^3 = \simeq 4\rho 125 = 500 \rho $ for $\rho$ the density. So we need $\rho \simeq 10^9$ kg per cubic metre. This is much denser than the densest element Osmium which is about 22 590 kg/m³. The conclusion is you cannot build something small enough out of ordinary matter to make the tidal forces relevant. So let's just take a solid sphere of osmium. [Eric James Stone](https://www.ericjamesstone.com/blog/home/gravity-calculator-for-astronomical-bodies-based-on-radius-and-density/) says that means we need a radius of about 1500km. Of course there are errors for how the matter is more dense at the centre. So lets say we need a radius of 1000km or so. That's certainly larger than 5m. **Added later:** The "largest possible" question is harder to answer. What you want to do is take a small dense object and build a hollow superstructure around it that is strong enough to support itself and the gravitational effect of the *singularity*. I'll go out on a limb and say the cube-square law prohibits such a large structure of any significant size. There is a hard limit at about twice the mass of Jupiter where the structure turns into a star. I'll guess the true upper limit is about nine times the diameter of Earth or 70,000km. Eric James Stone says a sphere of ice that size has about 1g gravity. We know there's no problem with that since Neptune is mostly ice. You could in principle build something larger using a less dense material. For example solid hydrogen has a very low density of about 0.08 grams/cubic cm. So you could try to build a ball of solid hydrogen. You need 1 million km diameter to get the right surface gravity. But that's much bigger than Jupiter so I imagine gravitational effects come into play long (LONG) before that to make the planet more compact. So let's say the size of Neptune. [Answer] Regarding the largest body. if you include artificially made bodies, the Birch planet ( the concept invented by Paul birch coined by youtuber Isaac Arthur) is a shellworld surrounding a super massive black hole with the option of making the gravity on the outer shell normal earth gravity it could in theory be a light year accross and still be considered one body Edit: Just to add that this is basically an upscaled shellworld. A shellworld can be built around gas giants to simulate earth gravity on the outer shell ]
[Question] [ **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. Cooling in space is a well known difficulty. There are many unpleasant consequences like [no stealth in space](http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth), difficult [space battles](http://www.projectrho.com/public_html/rocket/spacewardefense.php#radiators) which turn into a short wars of attrition (because you have to either pack your radiators, rendering them useless, or expose them, rendering them vulnerable), and many other complications. This is not only a problem with starships, but also with planets: even [Kardashev type I civilization](https://www.youtube.com/watch?v=HEpNiOM6lto) will run into problems keeping their cool if their energy usage on one planet already makes them a type I civilization. But what if one considers using a black hole as a heat sink? It seems pretty straightforward to just deposit the waste heat into the black hole, which would have a negligible increase on its mass. However, this seems to be burdened with a bunch of problems which should be addressed: * Keeping the black hole in place. They are not really objects you can simply grab and hold. But perhaps a charged black hole ([Reissner–Nordström](https://en.wikipedia.org/wiki/Reissner%E2%80%93Nordstr%C3%B6m_metric) or, perhaps even better, [Kerr–Newman](https://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric) black hole) could be held using some sort of magnetic confinement. * Black holes of any reasonable mass and sufficiently small gravitational field in their reasonable proximity have a *very* small Schwarzschild radius. Therefore, some precise aiming would be required and the question is whether this is possible to do with the waste heat. * Hawking radiation. Planets depositing their waste heat in black holes probably wouldn't suffer from this problem, but a problem would arise when trying to downsize to for spaceships. Any reasonably small black hole would emit too much Hawking radiation which would make it too hot to be of any use as a heat sink. Using a [black hole temperature calculator](https://www.omnicalculator.com/physics/black-hole-temperature), it is easy to see that a black hole with a temperature of cozy $300$ K will have a mass of over $4\times10^{20}$ kg, which is almost half the mass of [Ceres](https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)) - plausible for planets, but not so much for spaceships (unless we are talking about [something that can be easily confused for a moon](https://en.wikipedia.org/wiki/Death_Star)). But perhaps using an [extremal black hole](https://en.wikipedia.org/wiki/Extremal_black_hole) could help since it should not emit the Hawking radiation. Can these issues (and perhaps some other relevant key issues, overlooked in the list) be resolved to make a use of a black hole as a heat sink? If yes, how? [Answer] I have to disagree with most of conman's points. The issues described are merely engineering challenges, not fundamental problems. And in fact, they are engineering problems that - to some extent - have already been solved. The first thing you need is simply refrigeration. If you don't want your spaceship radiating thermal energy in every direction, then you need to pump the heat that would normally migrate out to your hull somewhere else. It is not necessary that this heat dump be cold. But the hotter it is, the more energy will be required simply to pump additional heat into it, which in turn increases how fast its temperature will rise. Traditional heat dumps will do if you only need to hide for a short time, and then can release that heat before it gets too hot to control. But as you've noted, long-term stealth is going to be difficult. So how about a black hole? They are not a good solution for a spacecraft. Assuming that the enormous difficulties in creating and controlling one have been mastered, a small black hole would make a excellent energy source, weapon of "mass" destruction, method of propulsion, but a truly lousy heat sink. Getting the heat into it isn't so hard as implied. You just use a [refrigeration laser](https://en.wikipedia.org/wiki/Laser_cooling) to cool your more traditional heat dump and focus your laser on the black hole. Difficult, but nowhere near as difficult as creation and control. But [Hawking radiation](https://en.wikipedia.org/wiki/Hawking_radiation#Emission_process) is not your friend. From the wikipedia article, the temperature of the black hole is given by $$T \approx \frac{1.227\times 10^{23} \text{kg}}M K$$ You need that temperature to be at the local background temperature for the black hole to serve as a useful heat dump to keep your ship hidden. Within the solar system, that is around $40\ K$, and of course much colder in deep space. But that means your black hole has to weigh on the order of $10^{22}$ kg, roughly half the mass of the moon. So your ship is going to have to be as massive as a planetoid, which just isn't feasible. So forget the black hole. But note that we now have our heat caught up in a laser beam. The great thing about a laser beam is that it doesn't radiate in every direction. For stealth, this is handy - for the enemy to spot you, they have to see the beam, which is highly unlikely. And even that vanishingly small probability can be reduced if you have some knowlege of a direction the enemy is unlikely to be in. Now the real situation is a little less rosy. Space is not empty. There are a few particles that are going to get in the way of your laser, scattering the light. If your laser is powerful enough, that scatter may be detectable at close enough a distance. You can mitigate that risk by diffusing the beam over a larger area, dropping the energy of the scattered light, but at the risk of increasing the size of the region where the laser is directly observable. It is a trade-off of near-by stealth vs distance stealth. For a civilization, the situation is more rosy. Go ahead and squeeze Jupiter down into a black hole. As long as you don't get too close, you won't feel any worse effects than you do now. As far as radiation is concerned, the only problems are those darn meteors and comets occasionally falling in, which will give off some nasty bursts of radiation as they fall. Aim as many refrigeration lasers at it as you want. You are not going to make a difference. But even then, pointing those lasers at the sun instead would work about as well. The lasers can easily be hotter than the surface of the sun, and serve almost equally well for refrigeration. The sun would not be bothered by this puny addition of heat, which would then be radiated back out into space disguised as ordinary stellar radiation. [Answer] Your issue is right here > > It seems pretty straightforward to just deposit the waste heat into > the black hole > > > Unfortunately this isn't true. The problem is that heat isn't something you can just dump into a black hole. To be clear, heat is just the random motions of atoms and molecules inside substances. There isn't a way to just "move" that into something else, regardless of your black hole's ability to absorb things. For reference, if you could somehow "move" the heat around without generating more waste heat in the process, you would have invented a lossless [Maxwell's Demon](https://en.wikipedia.org/wiki/Maxwell%27s_demon), violated the second law of thermodynamics, invented an infinite energy source, and won every single Nobel Prize in physics for the rest of history, all in one go. There is only one way you could dump heat into a black hole, which is by converting it into light and sending the light into your black hole. It turns out there is a way to convert waste heat into light. It is called [thermal radiation](https://en.wikipedia.org/wiki/Thermal_radiation) and all materials do it naturally and automatically as a result of being hot. Taking something which is hot and cooling it by allowing it to radiate its heat as light energy is of course the well known process of [radiative cooling](https://en.wikipedia.org/wiki/Radiative_cooling). The trouble is that when you try to use radiative cooling to cool something, the question of **where** the light goes is never the problem. The bigger issue is efficiency. Radiative cooling is very inefficient, so you end up creating large "fins" to increase the surface area to generate as much cooling power as possible. For example, the radiators for the active heat exchange system on the ISS are not as large as the solar panels, but are still one of the [larger features on the ISS](https://en.wikipedia.org/wiki/External_Active_Thermal_Control_System). This all means that the limiting factor with radiative cooling isn't where you send the light - in fact, you typically don't even care about that. Sending it off into empty space is as great as any other option. The limit is your total surface area available for cooling. Putting a black hole in the mix doesn't change any of that, so it brings no benefit to your cooling system at all. In short, we're right back to the problem you are trying to solve in the first place - the only way to dump heat into black holes is by radiative cooling, and that is what you were trying to avoid in the first place. In summary: 1. There is no way to directly transfer "heat" to a black hole. 2. The only way to get heat into a black hole would be by converting waste energy into light and sending that into the black hole 3. However, the main problem that makes cooling so hard in the first place are the inefficiencies involved in converting waste energy into light 4. If you came up with a way to efficiently convert waste energy into light you wouldn't need a black hole anyway - it would be sufficient to just send it into space. 5. Therefore, a black hole cannot help with cooling at all [Answer] > > But what if one considers using a black hole as a heat sink? > > > Yes in a simplistic sense black holes do act as heat sinks. But if you want to use them for cooling the heat generated by the energy use on a planet of a Kardashev type 2 civilization they are improbable, impractical and far too dangerous. The idea seems plausible if you ignore basic physics. The proposition ignores firstly the physics of radiation. Thermal energy will radiate isotropically, i.e., equally in all three spatial dimensions. Even a mere Earth-mass black hole (BH) will be about the size of the full spot at the end of this sentence\*\*.\*\* The beamed heat would have to be concentrated into an excessively narrow beam. If possible, this would be extremely dangerous. Fortunately, it's not likely. Imagine installing an Earth-mass BH on a planet of a K2 civilization. There will be the problems of gravity. Two centres of gravity. One, say, at the centre of the planet and the other on its surface. The engineering of keeping an Earth-mass BH in pace safely would be mind-boggling. One slip and it's disaster. > > It seems pretty straightforward to just deposit the waste heat into the black hole > > > Not so. It would take a "magic" technology concentrate thermal radiation into a beam to intersect the required BHs. The concept starts from an apparently plausible idea: BHs can act as heat sinks. To extrapolate this notion into mass-scale cooling systems for a highly advanced civilization further up the Kardashev scale isn't workable. While it is possible to contemplate the necessary conditions to make the technology work, those necessary conditions only highlights the *real* problems that would have to be overcome. The trouble is they are basic physics. ]
[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/113094/edit) I have a friend who is a square (i.e. he lives in a 2 dimensional plane on the surface of a table that I keep in my bedroom). He has decent hearing and understands English, but I'm getting tired of trying to explain this whole 3-dimensional thing to him in person. I'm wondering if I could just set up an API so he could access the internet then he could find things out for himself. Preferably he would be able to engage with GUIs, so that he could engage in forums such as this one. Any suggestions for the most practical way of setting up such an UI? The square is able to speak and move around in the plane. He is also able to hear sounds and to see reflections off of walls (shape edges) when I project different light onto them. --- Edit: @AlexP is right. I should have said UI. I've fixed it above. Also, I should clarify, I'll be building the UI in 3-space so no worries about technical challenges of building in 2 dimensions. There have been some good responses, but ideally I'd like for him to be able to interact with graphics. Any suggestions on how that could be accomplished? [Answer] ### Hilbert Curves Your square friend experiences the table as a 1-dimensional strip. You browse the web in a 2-dimensional browser. So it seems to me you just need to convert the 2-d array of pixels in your browser to a 1-dimensional array of pixels and place them on the the table. As un-intuitive as it sounds, this is possible with something called a *space filling curve*. Here's an example called a *hilbert curve*: [![hilbert curve](https://i.stack.imgur.com/Xuh8X.gif)](https://i.stack.imgur.com/Xuh8X.gif) [from Wikipedia](https://en.wikipedia.org/wiki/File:Hilbert-curve_rounded-gradient-animated.gif) The advantage of doing the map this way is that $(x,y)$ points that are close in the 2-d map are still close in the 1-d map. So locations of buttons, text, etc are consistent (if occasionally disjointed) when scrolling. Also, the 2-d array need not have the same number of points as the 1-d array, as evident in the animation. ### Example I whipped up an example of what this might look like. Consider the following $64 \times 64$ image (blown up for appearance): [![cat pic 1](https://i.stack.imgur.com/eUjXd.jpg)](https://i.stack.imgur.com/eUjXd.jpg) Now let's apply a hilbert transformation to take the $64 \times 64 = 4096$ stretch of pixels: [![cat 1d](https://i.stack.imgur.com/yvgtA.jpg)](https://i.stack.imgur.com/yvgtA.jpg) ( I duplicated it 256 times in a row so nobody would have to look at an image 1 pixel tall). Looks like a 1-d cat meme to me ;) ### Keyboard and mouse The keyboard is pretty easy; take a keyboard and lay the keys out in a 1-d array. The mouse input is a little trickier. You either have the option of mapping the mouse to the 1-d display or keeping the mouse mapped to the 2-d display and allowing your square friend to operate the mouse by moving on the 2-d table. Personally, I think it would find the 1-d mouse-map more intuitive. [Answer] The input should be entirely sound-based. Your friend should restrict his browsing to some large text-based source where the text has a predictable format. For example Wikipedia. Then you write a text-to-speech program that takes any page he specifies and reads it out for him. You set up 'buttons' on the table. . . [![enter image description here](https://i.stack.imgur.com/EWC5U.jpg)](https://i.stack.imgur.com/EWC5U.jpg) . . . where a light sensor notices the change in colour when he moves into the area. This allows him to input a string of characters for which page he wants next, as well as skip forward and backwards through the narration. [Answer] We understand data on the internet usually through a computer screen, essentially a 2D object. Your friend exists and thinks in 2D, but can only perceive 1D, assuming he cant see through walls (we exist in 3D, but only see 2D. Depth perceptions helps a lot here). The best way I can think of to send data in a way that he can read is through Morse code. If you have a network set up that allows him to visit pages, then any text on those pages could be converted into Morse code, and put onto a piece of paper on the edge of the table, allowing your friend to read it. Alternatively, if he can speak/hear, then a text to speech system would likely be much simpler for you to make and for your friend to get used to. [Answer] **A 2 Dimensional Being Cant Comprehend the 3rd Dimension....** To a 2 dimensional being you will only ever be a line segment with width corresponding to the amount of material in which your body bisects his plane of perception. To a 2 dimensional being a sphere would simply be a growing and shrinking circle as it passed through his plane of perception. There is no way he could ever possibly perceive or understand what more than 2 dimensions were without himself becoming a 3 dimensional being. [![enter image description here](https://i.stack.imgur.com/wvAMQ.gif)](https://i.stack.imgur.com/wvAMQ.gif) **...So we Will have to Translate Things to His Perceptions** As far as setting up a computer interface for him to both read and access data it would need to be translated from out spatial perceptions into his. I'm thinking a laser projected keyboard would need to be adapted into 2 dimensional symbols that he could decipher as letters of our alphabet. [![enter image description here](https://i.stack.imgur.com/tXNoy.jpg)](https://i.stack.imgur.com/tXNoy.jpg) I'm thinking a braille like system of lines and dashes corresponding to letters from our alphabet (he will have to learn to read this system too.) The computer would translate them into his version of braille as well as translate his input back into normal letters for the computer's use. For images you would "slice" a 3 dimensional rendering up and display them to him from top to bottom one slice at a time. He will never have a fully complete comprehension or understanding of what 3d actually is, but you now have given your flat friend a method by which he can interact with our world beyond sound. I think the 3d rendering slicer program could be adopted from 3D printing software. It could be adapted to be projected to him a slice at a time instead of being printed a slice at a time. [![enter image description here](https://i.stack.imgur.com/Cv8JR.jpg)](https://i.stack.imgur.com/Cv8JR.jpg) [Answer] **It should actually be no problem for a fully abled square, a bit trickier for a disabled square.** While someone like Stephen Hawkins, RIP, was indeed 3-dimensional, his physical ability to use a computer with standard inputs was limited to say the least. Luckily, we have designed various systems and devices to allow those with physical disabilities to use computers. The first step is the output, because you can't interact with a system if you have no feedback. I would presume, perhaps wrongly, that a 2D screen to a 2D character is the same than one of those fancy sci-fi 3D displays to a human, it might be overkill and unnecessarily complicated but should be comprehensible still. In case your 2D pal cannot make visual sense of the screen, there are accessibility options on Windows (and I would assume other systems) to describe what's on the screen. I've never used them, so I can't really vouch for them, but they are designed for people with visual impairment and I assume they work well enough. Now we'll assume your square has a good idea of what's on the screen. If he doesn't, chances are even turning him into a 3-dimensional being won't help. If your square can move, that movement can be detected (with a camera for instance, or something like a DDR mat), you effectively have a mouse pointer. If your square can speak on top of that, you need to set up a command for left click, right click, double click, etc. then setup a commercially available speech-to-text software for typing. That would be the easiest, most straightforward way to interact with a computer screen. In the case, your square can't move or speak, you'll have to tailor something around his specific abilities. Basic controls you'll need to map are selection (e.g. click), changing selection (e.g. moving the cursor, alt+tabbing), typing (which implies a vocabulary of commands for each letter plus some special characters, alternatively sounds or syllables instead of individual characters), and that should be enough to navigate the web. --- Remember that people with disabilities still would like to use computers, and that we have come up with solutions for them. Some of them may be native to your system, some might be commercially available, some might be more DYI, but it should still be doable. Obviously, someone who uses these should have more insight on their strengths and limitations than me. [Answer] If your square can see, even if only 1-dimensionally, he will probably have experience with viewing 2-dimensional space, just as we can get a good grasp of the three dimensions around us only by means of our 2D seeing. This means you could put a sheet of semi-transparent material in your cube's plane of life, onto which you project your computer screen (maybe with a magnifier applied). By moving around a little, the square could probably guess what's *in* the plane. If that is too difficult for him, you could even try projecting the image onto some mist that the square can move around in freely to "scan" it. This would probably still feel more natural to him than artificial slicing. ]
[Question] [ What would be the psychological effect on the inhabitants of a generational starship, if they discovered that powerful pirates were on course to intercept them 20 generations hence (~600 years), and there was no way to outmaneuver them? [Answer] You can make some pretty giant course corrections in 600 years, so I am going to assume you mean that both you and the pirates will be in the target solar system in 600 years, making the question of doing a rendezvous somewhat simpler (in relative terms). The most likely answer is the passengers and crew will do nothing. There are plenty of examples in our own history, for example the expansion of Welfare, Social Security and Medicare in the 1960's were all correctly predicted to be unsustainable even then, and now the United States (and indeed every Western nation which followed similar expansions of welfare and entitlement benefits) is essentially bankrupt, with an estimated *$100 trillion* in upcoming unfunded liabilities coming due as the "Boomer" generation reaches retirement (the problem will "solve itself" in the 2060's, when most of the boomer generation will have passed away...). So *we* have had 40 years to prepare, but both voters and politicians have chosen to ignore the issue or kick the can down the road a bit longer. Even the 2008 financial crisis should have been a very clear warning, but what effective steps were taken to deal with the underlying crisis of unsustainable debt? Since most humans have a time horizon measured in months and years rather than decades or generations, the starship will see every generation have a handful of Cassandras trying to warn everyone about the upcoming problem and everyone else ignoring them. This also makes the second assumption that a human society can function intact for such a long period of time. The Roman Republic lasted for about 400 years and the Empire another 400, but the Republic was radically different at the end than from the beginning, and the Empire changed almost beyond recognition during its time as well (and the Eastern Roman Empire was also dramatically different from both the Western Roman Empire, and institutionally and culturally very changed when it finally was overthrown in the 1400's). It is quite possible that the internal society of the starship will change quite radically in the intervening time and the concerns and issues of the landing crew will be far different from that of the launch crew. Indeed the Pirates might not be a threat in 600 years either, since there is no guarantee that they will have the same issues or mission objectives by that time. Indeed, it might be interesting to look at the problem from the POV of the *pirates*. What is keeping them focused on boarding and plundering 20 generations in the future? [Answer] **In our world that means a lot of computer power** You postulate, that we cannot do anything with attack in 600 years. I am going to question that idea a bit: To be able to know, that *something is going to get us in 600 years* in space means a heck of computer power, because *everything moves pretty fast in space* But, your ship was able to calculate with exact precission, that the pirates are going to get them. No matter the changed stars, no matter if the ship is going to sacrifice one or two generations in getting from A to B by slightly changing the course. [Space rendezvous](https://en.wikipedia.org/wiki/Space_rendezvous) is quite difficult maneuver. Especially if one of the ships *does not want to rendezvous*. In our world you could change trajectory of ship in very small order now and get more than million kilometers of difference in 600 years. Yes, as I said earlier. If goal of the generation ship is getting from A to B, this change of course would mean having the trip being longer by (say) one or two generations. Still better than to be attacked. But... But you said that even if my generation ship is going to do such small change now, the pirates are going to get them anyway. (Because you calculated that on your nearly impossible computer). You have these choices: 1. Party wild for 19 generations and let "them" deal with that. This is most believable approach, because on Earth and [global warming](https://en.wikipedia.org/wiki/Global_warming), loads of people have exactly that approach. And if you do not sort your waste, welcome to that group 2. Use your super computer to help you get an solution. If it can calculate trajectory to rendezvous in 600 years, given the speeds and vast emptiness of space, it is perhaps time to use it wisely and provide you weapons, or solutions 3. Think about how trajectory changes work and decide if the pirates can work out "small change now but huge difference in 20 generations" or "do nothing now and have huge change of trajectory in 19th generation". If they can, then you basically have only option 1 or option 2. Given human psychology, I can assure you that chosen solution would be number 1 [Answer] It really depends more on the type of generational starship. If we're talking about a Traditional Generation ship, a massive one-way vessel designed to keep hundreds or thousands of people alive for hundreds of years then colonize, there are very few reasons to engage in piracy. Since a Generation ship is so massive, you'd have to have an equally massive empty ship to take on the spoils... if you have anything smaller, the generation ship would just grow back the loss over time. It would be different if it is a Suspended Generation Ship (Such as in Hugh Howey's [Half Way Home](https://rads.stackoverflow.com/amzn/click/com/B003QCIPGK)), because the colonist's ship is going to be growing the colonists in a vat, matrix-style, only when they get close to the destination. Pirates can board and take what they like due to a skeleton crew (if there is a crew) onboard, with almost no pushback. Going back to a traditional Gen Ship, the massive time difference would psychologically impact both crews, not just the colonists. Over twenty generations (~500 years), the "incoming pirates" may * Divide the colonists on what procedure to take, resulting in a civil war of sorts * Spur the colonists to become more militant, ready to defend from the pirates, giving the entire society a militaristic bent. This could generate a society of warriors, think of it as Spartans (in Space!) at best, or at worse, destroy themselves before they even arrive. * Change in the eyes of the colonists, almost to diety-like status. The pirates may turn into avenging angels, messiah-esque saviors, the denizens of the underworld, or just be representative of a coming judgment. They also may just fall into myth, so the colonists largely don't believe that they're coming. What I would think would be the most interesting is if you also show the opposite happening with the pirates themselves, because 500 years would also do a number on them. They may go through similar social evolution. It could be interesting if, for example, the colonists militarize waiting for these pirates, but the original pirates go in a spiritual direction and view the generation ship as a promised land of sorts. [Answer] One purpose of a generational ship, besides colonization, might be 1st contact with other species. Pirates may be a scary thing to consider, but with 20 generations of advanced warning, a plan to "talk to them" might be considered. People may already consider themselves "slaves" to the ship for the next 20 generations. A pirate takeover could be considered "liberation" to some. Explaining to the pirates your people have used these supplies and technology for 20 generations might make it easier for you to let you live and "run things for them". At the very least, maybe they will agree to drop you off at the nearest inhabitable planet if you give up without a fight? Spending resources to fire a big weapon, or risk of possibly damaging their prize, might be a fair trade for a little cosmic "bus fair" Thus: Colony successful. Although, maybe with less supplies. [Answer] What is the pirate's motivation? I presume by the word "pirate," they intend to plunder the contents of the ship. On the sea, this involves disabling the enemy and then sliding up to board them. .. but what's this board thing involve anyway? One of the fundamental requirements to board and steal stuff is that your relative velocities have to be really small. But that's in direct conflict with the nature of intercepting the generation ship, which requires a large closing velocity. The only way this could happen is if the pirates were close enough. Interestingly enough, this also implies that the pirates must also either be launched in a generation ship themselves, or have not yet launched, but intend to launch from a point directly on your path. If they are a generation ship, their acceleration is probably not all that hot, so they would have to have been launched really-really close to you. You probably know them. Go hail them, use a personal solution because you probably know the faction that launched the pirate ship. There cannot have been much of a time gap between launch times, or the relative velocities required for intercept would be excessive to bleed off for boarding. This leaves the last possibility, that they are almost perfectly along your path, and intend to wait for you to race by before launching their pirate ship after you (using a ton of fuel to accelerate rapidly). This is where the 600 years can be a godsend. If you vector around them, they will be forced to move not just the high-acceleration pirate ship to keep it near your intercept course, but move whatever platform it's waiting on. At some point, scorched earth becomes a valid approach. As you vector off course, and they align with you so that intercept is possible, they burn lots of resources. At some point you can communicate with them, and offer to split the resources you have. Make it clear: if they don't leave you with enough resources to make the trip, you'll just scuttle the entire generation ship (why bother continuing a journey, no matter how important, if you can prove you lack the resources to make that journey worthwhile). They're having to expend resources because you're not making it easy on them. Pirates who are moving entire launch platforms into the path of oncomming generation ships can't afford to be wasteful with their fuel. They need enough to make a profit. [Answer] Interesting read and replies, however in my opinion generational starships are already dead before they even exist. Whizzing through space at high speeds, for several 100 years is NOT the way we will get around the universe. We will be stuck here on earth until we figure out teleportation/wormhole/jump/warp or some other mode of transportation that enables us to ignore the current laws of physics as we know them. Why? Because near light travel is dangerous, slow, impractical and even more poignant: socially and politically unpredictable. If we ignore the distances, the odds of hitting something, and even the best case travel times (all of which are all terrible) think about how much society has changed on earth in the last six hundred years. We went from religious zealot misogynistic warmongers to moon walking entitled vain sedentary consumerists intent on our own extinction through sheer consumerism. You could put the brightest, kindest, most peace loving individuals on the ship at the start of the voyage, but by the time they arrived, they could turn into racist war hungry cannibal murderers...there would be no way to control the outcome, so why even bother to begin with? ]
[Question] [ I am creating a Medieval empire. It is following the [feudal system](http://www.wikipedia.org/wiki/Feudalism) and I want to avoid the extreme political breakup that happened to Europe in the Middle Ages. How would I limit the power of feudal lords to retain an effective Monarchy? [Answer] According to historian [Peter Heather](http://rads.stackoverflow.com/amzn/click/0199368511), the force that leads to the weakening of central governments in feudal states of the Middle Ages is due to the limitations of the non-cash economy in these times. Basically, in Ancient times, an Emperor could reward a follower with cash and jobs that come from tax revenues. These recur every year, so he can keep granting favors without losing his own assets and power. In Feudal times, the grants must be in land, which the follower uses to support himself. A land grant once given, is gone, and the king is now poorer and the noble classes stronger. An exception is if the feudal state is on a border with a weaker foe, and can expand to grab more land or loot which can enrich a worthy follower but not eat into the King's lands. But this usually doesn't last long. So the key seems to be for the King to find a "renewable" source of wealth or value that he can dispense to nobles as a substitute for grants of land. [Answer] Oldcat and SJuan76 have definitely provided a comprehensive answer to the OP's question, but I would offer another factor which might contribute to feudal fractioning. **Communications** The larger a kingdom grows, the harder it is for a King to stay informed about the challenges facing his Feudal lords. More and more, the lords are left to manage their lands alone or in concert with other local lords. Help when it does come down from the throne is often inappropriate in both timing and scale. It is only natural for the lords to begin to feel alone in their duties and to resent the meddling of the crown. A charismatic King in close concert with all his lords, could easily maintain their allegiance by constantly highlighting the mutual benefits which arise from the bi-directional sharing of loyalty. But a King in absentia, isolated from current knowledge and unseen for long periods of time cannot inspire or maintain such loyalty. So if you are building a medieval kingdom in a fantasy setting, and you want that kingdom to grow large and survive, give them a good communications network, maybe something magical, so that your King can stay present and involved in the lives of his lords. -- edit to acknowledge a clarification from the comments -- In this way, a clever leader (King) can keep his supporting staff (Lords) from rebelling and keep an eye on any rebellious staff (Lords) so they can be replaced before they become a problem. [Answer] If you are not limited by science (as you marked post as fantasy-based), easiest would be charismatic king who is also immortal. [Answer] You could take [Louis XIV's](http://en.wikipedia.org/wiki/Louis_XIV_of_France) approach and keep the nobles so busy on attending the demands of the king that they don't have the time or opportunity to break away. I mean sure, the ultimate outcome of Versailles was the french revolution, but during Louis XIV's reign, it worked very effectivley to keep a tight grasp on his vassals. [Answer] Some possible approaches... You could hold their families **hostage**. All feudal lords might be required to spend part of the year at the capital under the power of the King and leave their families behind when they go elsewhere. Japanese used to do this, IIRC. Similarly as CMaster pointed out the French used a softer variant of this where the nobility had to attend to the King at the court at the expense of having the time to build an independent power base elsewhere. Attending the Court was also expensive and made it harder for the lords to gather wealth they might use to challenge the King. A variant might require noble children to be educated at the capital. **Religion** has been used to create cohesion. The Roman Emperor was also the pontifex maximus, the focus of the imperial cult, and later the de facto head of the church. The Chinese Emperor had the mandate of the Heavens to justify his rule. The Japanese Emperor was of Divine bloodline. And the Achaemenids were the protectors of the religions of their subjects and were in return largely supported by the various local religions. The point is that when the rule of the King is justified by religion, rebellion becomes evil thing to do and it is harder to get any support for it. **Alliances** are very much part of the feudal system. All the noble families are vassals of the king, but some families have closer connections with the ruling family than others and generally less likely to rebel. Favor those families slightly to keep their support and make sure that all the critical locations are held by one of your close allies. Specifically, it should be impossible to threaten the capital without fighting your way through your most trustworthy allies. You also should prevent possible challengers from building their own alliance networks. **Fear** is useful. You don't need to terrorize your subjects or vassals, but they should be aware that you can and will remove them, if they lose your trust. Basically you need to show that the fiefs are **not** permanent, if you have reason to decide otherwise. Even if that requires starting a war. Just remember to have that reason or your heir will have issues. And assassins do work. **Balancing factors** to the power of nobility are good. Religious organizations (which should be controlled by or closely allied with the crown) can prevent nobility from having a power monopoly and support monarchy. In many countries the urban middle class was a key support for the King against the nobility. Cities might have walls and militias that give real military power. And the taxes they pay might allow a standing army loyal to the King to be stronger. A smart King might have recognized that the cities will become more important in the future and traded control over cities for giving nobility rights to the land. This would create a natural increase in the power of the crown over time. King should support the growth of cities and trade and protect the rights of the middle class. **Rule of Law** supports the central government. So a strong legal system helps the monarchy. Provided the King is not obviously breaking the laws himself. If the legal system makes clear the the laws of the King are above the rulings of the noble Lords that makes the monarchy stronger. [Answer] ## **Fall of Rome** You should keep in mind that feudalism is the result of the fall of Rome via barbaric invasions. So we should analyze what held Rome together and what feudalism lost when Rome fell. A empire is a political entity based on two main factors: **Economics:** The Roman empire grew steadily across hundreds of years. This means that during the timespan of its existence commerce routes and economic specialization were established. So, this leads to economic integration, meaning that a single political entity is unavoidable and something that can decrease wars and other forms of trade disrupting activities over a large surface. Another desirable consequence of a large political entity is capacity to build large infrastructure that foments commerce on a larger scale. **Ideology:** Romans were proud of roman identity. To be roman was to be civilized. This pride manifests itself as a desire to be part of the empire. There are no Romans if there is no roman empire. So this ideological concept is strong enough to bind the empire together. When Rome fell due to the barbaric invasions both the trade routes, commercial specialization and national identity died, so in order to avoid feudal fragmentation (something tried by Charlemagne) you should fulfill those objectives. Your empire should be built slowly, you should incentivize non-subsistence economical activity, so as to promote commerce. etc. keep and build routes. fund cities. etc. [Answer] One possibility would be to eliminate one or more of the top-tiers of nobility. In Europe this would be the [Dukes](http://en.wikipedia.org/wiki/Duke). This leaves you with the next step down - Counts - as the "top-tier" nobility. But because there are more of them, the individual power of any one Count is very reduced compared to the power of a single Duke. Now, the King/Queen will need to create additional bureaucracy and military levels to handle what Dukes previously did, but they will have more control over those levels. Of course, *in total* the Counts will have similar collective power to all of the hypothetical Dukes, but they won't be able to concentrate and apply that power as well. More importantly, the King can use his direct control to prevent the Counts from forming large alliances against him - he can use his levels of bureaucracy to break up large alliances. ]
[Question] [ Could you build a ring around the earth, so that it would just sit in the sky? I'm not talking a geostationary orbit of rubble like the rings around Saturn, but a solid structure just high enough to clear Mt Everest. As gravity would be acting equally on it from all sides it would just hover there wouldn't it? Structurally it would be uniformly under compression as gravity would be trying to squeeze it inward, so a substance such as concrete would be perfect, and cheap too. Kind of like a giant masonry arch that keeps going right over the horizon. Although the main reason for building such a structure would obviously be the lulz, I can think of one use: if you were to rotate it it could be used as a transporter - like a giant version of those moving footpaths they have at airports - 'travelators' I believe they're called. You could even have different rings at different heights going in other directions. So would this be possible, physically, and economically? Should I start a Kickstarter campaign? [Answer] Structurally, if my math is correct, no, it cannot hold together if made of concrete. We can consider the ring as being analogous to a thin-walled cylindrical pressure vessel with a negative pressure. We start by describing the pressure: $$P = F/A$$ Here, $A$ is the area of a given portion of the ring and $F$ is the force on the area. The force is equal to $\text{ gravity} \times \text{ density} \times \text{ volume}$, where the volume is the area of the portion of the ring times its thickness, or $$F = g \times \text{ density} \times V = 9.8 \times 2400 \times A \times t$$ $t$ in the above equation is the thickness of the ring. This can be plugged into our equation for pressure to yield the following value after cancelling out $A$ (area) in the numerator and denominator: $$P = 9.8 \times 2400 \times t$$ The tensile force for a cylindrical pressure vessel is $\frac{Pr}{t}$, although we have a negative force since gravity is compressing our pressure vessel, so we'll have an equivalent compressive force on our ring. We can plug our pressure equation in to get the following, after cancelling out thickness: $$\text{ stress} = \frac{Pr}{t} = 9.8 \times 2400 \times r$$ $r$ in this case is the radius of the arch, which is roughly equal to the radius of the earth, or around $6370 \text{ km}$. We want this in meters to get stress in $\text{ MPa}$, so we'll convert to $2400 \times 9.8 \times 6.37 \times 10^6$, which comes out to around a total of $150 \text{ GPa}$, which is far greater than the compressive strength of concrete, which is around $800 \text{ MPa}$ for ultra-high performance concrete, and also much higher than the strength of materials such as steel or quartz. It's on the same order of magnitude as the compressive strength of diamond, but diamond is about 50% denser than concrete, so it would still probably fail. The stress is around the same point as the maximum predicted stress of nanodiamond, but this hasn't been tested in a lab. Values used for calculations: * Acceleration due to gravity of $9.8 \text{ m/s}^2$ * Concrete density of $2400 \text{ g/m}^3$ * Radius of $6370 \text{ km}$ * Maximum compressive stress of $800 \text{ MPa}$ All of this is under the assumption that the ring is relatively stationary with respect to the earth. [Answer] Ringworlds have been around for a while in scifi. One major issue with sticking them around other objects (like planets or suns) is that they're inherently unstable in that scenario: <https://physics.stackexchange.com/questions/41254/why-is-larry-nivens-ringworld-unstable> Your object isn't really a ringworld but it would suffer from the same issue. Since gravity isn't *perfectly* equal all the way around, one side would fall, which destroys the integrity of the rest and would lead to it crashing to the ground. [Answer] # Build it on Space and include expansion/contraction joints So, you mentioned concrete right? Building it on the ground and then hoisting the pieces up sounds damn near impossible to me, many things would have to be considered: space for building, clearing whole areas for construction, activists against clearing wildlife reserves where one of the temporary pillars would stay... I really think it should be built in space, using material found already in space. Sending the resources into orbit would be way to expensive. That is how I see it: 1. Build it in space, using resources already out there 2. Like bridges, have built-in expansion-contraction joints, huge ones, to prevent faults in the overall extructure 3. Make it bigger (diameter wise) than it needs to be 4. Set it on place around earth 5. Contract joints to desired diameter (to make it hang lower on the sky) 6. Add rails for cranes/hoists on the bottom, rotate ring for longitudinal movement and go up and down rails for the latitude. 7. Hoist any cargo, move up and down / rotate to deliver anywhere on earth The cranes on the bottom, like carts on rails, allow for many things to be added, like a huge lighting system, whenever a nation suffers from natural disaster you could rotate the ring so it hovers over it. Light up the night to help the rescue teams, you could pour water to extinguish fires, hoist people up for medical treatment on ring facilities... I cant help you with the technical issues, how much it would weight, how wide/tall it should be, etc.. but I believe if such a structure would be possible, many possibilities would be open, like: Solar panels on the outward side of the ring. Base jump sport is the new trend? Most badass bungie jump ever? Home for the elite class? Polution goes rampant down there, everything allright up here. Skyport, biggest runway on top (railgun like?) or cataput to send cargo into space? People could fly down on gliders, later the gliders are hoisted back up. [Answer] Such a ring is inside the Roche Limit, so tidal forces of the Earth's gravity would tend to tear it apart. Also, unlike an object in orbit, where the orbital speed balances gravity, this ring is not anchored to anything. Any impetus vertically would allow the ring to drift relative to earth until one side or another collides with the ground. [Answer] No, spare your reputation and your finances and the people of planet Earth--no Kickstarter for this one. A ring satellite would be **short-lived**: The propagation of waves through the solid material results in nonuniform gravitation, which will generate *more* waves and hasten the ring's demise. Creating expansion/contraction joints would only transform the waves into more nearly inelastic collisions instead of elastic ones. If the wave propagations are elastic, they build up over time until the ring shatters due to the vibrations. If they are inelastic, they will steal energy from the ring's angular momentum and it will crash into the planet by gravity. Either way, you will be have to be putting enormous amounts of energy back into your ring to keep it "afloat" (in orbit) in order to compensate for these losses, and to damp oscillations to prevent self-destruction. This fact alone makes the economy of such a ring unsustainable. James Clerk Maxwell found that a solid ring around a planet would be unstable and could not exist for long: > > "...the stability of the motion of a solid ring depended on > so delicate an adjustment, and at the same time so unsymmetrical a > distribution of mass, that even if the exact condition were fulfilled, > it could scarcely last long... These considerations, with others > derived from the mechanical structure of so vast a body, compel us to > abandon any theory of solid rings." > > > In this Essay Maxwell proved that the only stable configuration for a planetary ring is disconnected (fluid or solid) particles, each behaving like an isolated satellite. In his introduction to the essay, Maxwell also wrote: > > "The Saturnian system still remains an unregarded witness in heaven to > some necessary, but as yet unknown, development of the laws of the > universe." > > > <https://archive.org/details/onstabilityofmot00maxw/page/66> As it turns out, the mathematical condition that Maxwell derived for the stability of Saturn's rings is the crux of automatic control systems--ultimately making computer-controlled **space flight** a possibility. His discovery is known as the [Criterion for the Stability of a Dynamical System](https://en.wikipedia.org/wiki/Stability_criterion), and it is used in virtually every modern control system and field of research, from anti-aircraft guns to automobile cruise control to robots to medicine and epidemiology. ]
[Question] [ **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. Normally, the human retina contains four types of light-sensitive receptors: three types of cones and one type of rods. The receptor proteins contain the chromo — iodopsin in the sticks, the rhodopsin in the cones. The role of the latter in bright lighting is insignificant, so for a person there are three "basic" colors: blue, red, green — all the shades we perceive are formed by their combinations. Since each of the yodopsins allows you to differentiate about a hundred shades, a person with normal vision is potentially able to distinguish about a million color combinations. Adding another type of receptor increases this number to one hundred million. Concetta Antico is a carrier of a mutation in the "red" iodopsin gene, whose sensitivity has shifted to the short-wave region. Special features are best displayed when distinguishing reddish-yellowish and purple shades: the color scheme of her paintings focuses on these colors. The additional color pigment also increased color sensitivity in low light, allowing you to distinguish between shades at dusk and in the shade.  The eyes of the mantis shrimp (Oratosquilla oratoria) have 16 light-sensitive receptors. My question is: What needs to be changed in the structure of the human eye to be able to see ultraviolet and infrared radiation, as well as to be able to see better in the dark ( That is, to have a good enough night vision). And at the same time distinguish significantly more colors in the visible range ( if you consider that the appearance of the 4 receptor allows you to distinguish 100 times more colors than ordinary people. Then when the same 16 light-sensitive receptors appear, we can distinguish hundreds of millions of colors, or even several billion! )? Also keep in mind that you need to turn the chromatins in the retina so that the nerve comes out from behind, not in front. This will remove the blind spot to reduce the overall length of the nerve and provide a greater amount of chromatin for each surface area. With appropriate adaptation of the primary processing layer on the back of the eye ball (duplication and offset integration), which can be used to increase the speed of perception by a factor of 2x to 4x, or the details of perception.  ( Human eyes absorb 90% of all photons before they reach the photon receptors. And we need at least 9 photons hitting an individual receptor before it registers a light source, (before it "sees something). This means that by gluing the receptors further forward, we could (optimally) increase the light sensitivity by a factor of ten. ) When making decisions, it is advisable to familiarize yourself with similar questions, where there are several interesting solutions that it is desirable to combine: [Colors of Things Outside the Spectrum](https://worldbuilding.stackexchange.com/questions/29645/colors-of-things-outside-the-spectrum?r=SearchResults) [How to modify the human eye to see into the ultraviolet and infrared bands?](https://worldbuilding.stackexchange.com/questions/29665/how-to-modify-the-human-eye-to-see-into-the-ultraviolet-and-infrared-bands/29752?r=SearchResults#29752) Supplement: Please offer solutions related only to biology, so no implants or artificial eyes. Also do not ask questions regarding too much information and the difficulty of processing ( if you know the ways of how you can reduce the difficulty of processing, I will be glad to hear ). [Answer] **Vision in the near UV part of the spectrum is easy**: humans can already see it. The receptors in the human retina can see light of about 300nm, but the lens filters out light below about 400nm. It is thought that the 'blue revolution' in Monet's art lat in life was a result of his cataract surgery, after which he was able to perceive different colours than he was able to before, and most especially, was [able to perceive UV light](https://www.newscientist.com/lastword/mg24432591-000-super-seers-why-some-people-can-see-ultraviolet-light/). A number of post-IOL surgery patients have reported similar effects, namely, that they can see a different kind of purple. Usually, lens implants filter out UV light; but some patients report that they can see this "extra purple" around their peripheral vision -- where the IOL can't physically filter. This would be the easiest fix, in all likelihood. Change the structure of the lens to allow the already visible UV light into the eye. [Answer] There are two things involved: 1. ability to sense a larger range of colors - including extended wavelength range **and** chromatic dimensions. Have to do with the human eyes transparency at different wavelengths and the fact retina is using only three dyes (or less, for the cases of color-blindness) 2. ability of the brain to combine the sensed signals Links - apologies, but I'm too tired to organize a coherent answer. * [The forbidden colors experiment](https://www.youtube.com/watch?v=cQCsDfEqr9o) - why you can't see yellowish-blue and what you can try to assess if your brain actually could * [photopsin - a carotenoid bound with different proteins](https://en.wikipedia.org/wiki/Photopsin) is the dye that allows the tri-chromatic vision of the human eye * [rhodopsin - the pigment+protein combination for night vision](https://en.wikipedia.org/wiki/Rhodopsin). * [A Team of Biohackers Has Figured Out How to Give People Night Vision](https://www.mic.com/articles/113740/a-team-of-biohackers-has-figured-out-how-to-inject-your-eyeballs-with-night-vision) - used a chlorophyll analog called Chlorin e6 dropped in the eye, effect up to 100m at night time. Their [project page](https://scienceforthemasses.org/infrared-project/) - heaps of other links, mostly to scientific articles * wanna see in UV? Make [cornea/crystalline lens less prone to damage on UV exposure](https://www.google.com/search?q=cornea+uv) first, we'll look into UV afterwards Right. If you don't want to mess with your eyes, get around [using sonochromatism](https://en.wikipedia.org/wiki/Sonochromatism) - your brain is quite plastic. If it works, go say thanks to [Neil Harbisson](https://en.wikipedia.org/wiki/Neil_Harbisson) [Answer] The first step is to give a look (pun intended) at the retina of most birds eyes, which [have a 4th cone type to see UV](https://en.wikipedia.org/wiki/Bird_vision#Light_perception). Differently than mammals, their cones have an oil drop to better constrain the wavelengths detected and reduce the overlap with other cone types. Also, [birds' cone are much more thin than mammalian ones](https://en.wikipedia.org/wiki/Cone_cell#Shape_and_arrangement). However, birds also have some downsides. [Mammals perceive contrast better than birds](https://en.wikipedia.org/wiki/Bird_vision#Contrast_sensitivity) and [birds have a pecten inside their eye blocking part of their view creating large blindspots](https://en.wikipedia.org/wiki/Bird_vision#Anatomy_of_the_eye). Their retina [have no blood vessels](https://en.wikipedia.org/wiki/Retina#In_birds), so this is the reason why they need the pecten. Also, humans, like all vertebrates have an [inverted retina](https://en.wikipedia.org/wiki/Retina#Inverted_versus_non-inverted_retina), which means that blood vessels and nerves are in front of the rods and cones instead of behind them. Cephalopods have non-inverted retinas. [Cats have a tapetum lucidum](https://en.wikipedia.org/wiki/Cat_senses#Sight) behind the retina to allow them see better in the darkness, but at the expense of decreasing their visual acuity. As [elemtilas](https://worldbuilding.stackexchange.com/a/169698/3002) said, people who get a surgey of cataract can see some UV. See [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860240/) for more about that. Further, even on mammals, [reindeers do sees UV light](https://www.ucl.ac.uk/news/2011/may/reindeer-use-uv-light-survive-wild). [For IR vision, that is more complicated.](https://sciencing.com/animals-can-see-infrared-light-6910261.html) The reason is that since mammals are warm-blooded, they simply glow in the near IR-range, so any receptive cone would be always saturated and blinded. Animals which are able to see some IR are all cold-blooded, mostly are insects, but some cephalopods, crustaceans, molluscs, fishes, amphibians and some snakes do see IR. But no way birds or mammal can do that. Note that altough snakes see IR, they don't use their eyes for that, instead they use their [pit organs](https://en.wikipedia.org/wiki/Infrared_sensing_in_snakes), as if those are a distinct set of eyes for detecting IR, but with a very poor visual acuity, resolution and contrast. So, to add IR vision, you would need to somehow shield the eye from the body own glow. So, I think that you could: * Start with a human eye. * Replace the mammal cones and rods by avian ones, including adding the avian UV cone. If you are unable to do this, try to at least introduce the reindeer UV cone. * Make the nerves and blood vessels connect them from behind the cones and rods, instead of in the front of them. This would also allow those cells to collect more light and be better vascularized. Then they could also be cramped more tighter, yielding a sharpen image. Since the much better vascularization also gives those cells more nutrients and oxygen, I think (not sure though) that they would then be able to yield a better contrast and get rid of the need of having either pectens or blindspots. * Make a special tapetum lucidum in the eye that can progressively change from reflective in darkness to opaque black under direct sunlight to make better adaptation for different light conditions beyond what the iris is capable. * Change the IOL in the eye for something that is also transparent in UV, maybe you can get an inspiration from reindeers to keep it compatible with being mammal. * You end up with three layers at the retina. The internal one features rods and cones. The other two are (a) the blood vesses, nerve endings and [retinal ganglion cells](https://en.wikipedia.org/wiki/Retinal_ganglion_cell) and (b) the tapetum lucidum. Not sure which one would work best as being the middle layer. Adding a UV cone might have a few downsides. Notably, if you add a new type of cone in the retina, you will need to spread the existing ones a bit to make room for the new ones, which might reduce visual acuity. Also, human eyes focus images with the red and green cones while the blue ones suffer from chromatic aberration and due to them being far less numerous, poor visual acuity in the blue. However, it shouldn't be very hard to balance this, specially if you use avian cones which are much thiner than mammalian ones. Also, the human brain already does a pretty good job "photoshopping" the image from retina to compensate for a lot of the vision shortcomings. > > Then when the same 16 light-sensitive receptors appear, we can distinguish hundreds of millions of colors, or even several billion! > > > Unlikely to work as you think. It is probable that seeing so many colors would require the correspondent neuron wiring in the brain. So, altough some animals have a large number of photo-receptors, this could be at the expense of being unable to properly blend all those color or having trouble to discern different similar shades of the same color or something else. Also, user MJ713 [points out in a comment](https://worldbuilding.stackexchange.com/questions/169692/see-more-colors#comment531092_169721) that [research on mantis shrimps shows that they are actually fairly bad at distinguishing between similar colors](https://science.sciencemag.org/content/343/6169/411). About tetrachromacy, I will cite [this](https://web.archive.org/web/20120214002707/http://www.klab.caltech.edu/cns186/papers/Jameson01.pdf): > > However, the most stringent test of our hypothesis was between the female trichromatic subjects and the female four-photopigment heterozygote subjects. As shown in rows 1 and 2 of Table 2, the mean numbers of bands delineated by the two groups of females (7.6 vs. 10) were significantly different ( p < .01). This comparison eliminated differences in performance attributable to gender and thus was a stronger test of our hypothesis that having four pigments yields a perceptual difference. > > > > > At present, four-photopigment female individuals are reported to be rather common, by some estimates occurring in up to 50% of the female population (M. Neitz, Kraft, & J. Neitz, 1998). It is also the case that an estimated 8% of males presumed to be color “normal” likely represent a four-photopigment retinal phenotype (expressing multiple L-pigment opsin gene variants that could significantly contribute to color vision; Sjoberg, M. Neitz, Balding, & J. Neitz, 1998). > > > I.E. There could be more tetrachromats around us that we might be aware. Even most of the tetrachromats themselves must be unaware. Also, excelent to read: * <https://webvision.med.utah.edu/book/part-vii-color-vision/color-vision/> and in fact everything on <https://webvision.med.utah.edu/>. * <https://theneurosphere.com/2015/12/17/the-mystery-of-tetrachromacy-if-12-of-women-have-four-cone-types-in-their-eyes-why-do-so-few-of-them-actually-see-more-colours/> * <https://www.sciencedirect.com/science/article/pii/S0960982214013013> Also, some years ago, I seen a paper where someone made an experiment with many women and found out some tetrachromats and even identified two different types of tetrachromats with functional tetrachromacity. If my memory don't betray me, one of those groups had an orange as the 4th primary colour and the other had a greenish-yellow as the 4th primary color. However, it was some years ago and googleing for it I was unable to find it again. This basically happens because the red and the green cones are encoded by two genes called OPN1LW and OPN1MW (ha, could find their names with Google at least), which are neighbours in the X chromosome (but absent in the Y chromosome), so during crossover (for women only), a gene that is a mix of half-OPN1LW and half-OPN1MW might end being produced, and there is more than one way to mix them. Also, in the same occasion some years ago, I also seen a very good webpage which described in profound details, but still in a clean and easily understandable language, all the nuances of how the color vision evolved and how it worked out in the retina, in the [retinal ganglion cells](https://en.wikipedia.org/wiki/Retinal_ganglion_cell) and in the brain. However, once again, Google betrayed me. [Answer] Check out tetrachromats if you'd like to know about people (specifically, women) who can see more colours in the existing visible waveband - their vision is to ours as ours is to red-green colourblind people, thanks to having a fourth type of colour receptor. UV and near IR vision may not be that helpful. Seeing in seriously low level light requires enhancements that no biological creature has - instead evolution equips night hunters with echo-location, scent, vibration sensitivity or good hearing (as in owls) instead. In practice you might be bettor off with better post-processing than better eyes, eg the ability to do the equivaltn of combining a large number of frames of video to get a best image. This can greatly enhance both daytime long-range and night imaging. [Answer] I'm not sure on the color issue other than human eyes are actually capable of seeing more shades of color than a computer screen can render (using a RGB scale)... meaning that their are colors you can only experience in real life. Not on a screen or on photos. As for night vision, many animals (cats come to mind) are more photosensitive than human eyes, both by having more receptors and by being more dilated (reducing the absorbed photons before they reach the receptors). If you've ever gone to an eye doctor, you've probably had your eyes dialated so he can look at them... and then suffered as the sun is ridiculously and painfully bright for the rest of the day. It's almost like being a vampire. Most night vision for humans is done by goggles that have a small computer in them that will take in photons from the lenses and render them on a screen for for normal human photo-sensitivity (that Night vision green, mostly done because the simplest monitors for these are gonna do green screens). You should not use these anywhere near a light source as it can blind you if the sources is something a naked eye can see just fine with. The US military also has special gun sights that are invisible to the naked eye but when you wear night vision, you can see them on the target (I assume other modern militaries have them, but it's only been described to me by US Military people... they all seem impressed that they can light up the bad guy "like a Christmas tree" and he's totally oblivious to just how much laser sights are on him. Gear for Infrared and Ultraviolet (and every other part of the non-visible light spectrum... which is to say, most of it) are similarly rendered into visible colors humans can understand. An Infrared will paint a source from violot (low) to red (high) and white (highest) based on the intesity of the infrared light because those are colors we can see, not because Infrared lets you see "more redder red". If you could see infrared, it would probably look like a totally new color you've never seen before (and because we rarely consider it in decrative color, almost all the colors would change based on their reflection of IR light. It's probably best to not describe the color or IR or UV because color is a qualia adjective. You cannot describe color without providing an example of that color. Though you could have fun with this as the person with enahnced color range could be disgusted with the ugly color combo of the fashonista (who is insulted that her perfectly matched outfit looks garrish to his eyes) or handle it like th Kaminoans in Clone Wars (the set was designed with a sterile white look, but this was explained as the Race seeing UV spectrum colors. While we find the whole appearance white and boring, the Kaminoans are stated to actually have some really amazing artwork all over the place that humans cannot see (most of this was in supplemental material and set designer notes If you squint you can see some vague outlines of intricate etched designs). ]
[Question] [ Airships are cool, and I would love to use them and see them used outside of steampunk a lot more. One key aspect of Airships is that they seem to have the square cube law reversed. For other things in the world they'll be able to carry less weight the bigger they are while Airships will have more gas volume and more lifting capacity because of it. At first glance that might mean that Airships can be almost unlimited in size. But there are (potential) limiting factors. For example the Hindenburg needed to vent large quantities of its lifting gas as it crossed the atlantic to prevent gliding off too high as it burned fuel and became lighter during the trip. There's also the structural stength of the frame to consider, as forces from the engines, wind and steering will need to be supported by the Airships envelope or risk breaking apart. The question I'm asking is: what is the (approximate) maximum size an airship could be? [Answer] Lockheed Martin is currently releasing a prototype for a new range of airships that are designed from scratch to be the biggest in the world. The [LMH1](https://www.dailymail.co.uk/sciencetech/article-3485488/Inside-Lockheed-s-giant-blimp-Long-range-LMH-1-airship-carry-cargo-people-remote-locations-world.html) is an airship capable of lifting 20 tonnes of cargo, but they also state that the design can scale up to a carrying capacity of 500 tonnes. Why 500 tonnes? Why not 5,000? I don't know the answer to that although I suspect that it's a matter of practicability - despite the inverse square cube law applying as you rightly point out, there reaches a point where even the most powerful engines can't compete with the sail area such a volume represents. Also, helium is a valuable and non-replenishible resource; there are already many doctors out there arguing that helium should be restricted for use as a medicine so that we don't run out of it. Getting that much helium together for an airship in the future may well be the limiting factor because of the cost of the gas. That said, you wouldn't vent it to manage ballast weights, you'd just pump it back into high pressure containers for reuse, but I digress. Of course, one of the other limiting factors is size. Once you go beyond 800m in length, the practicality of storing or hangaring such a machine can become problematic. Not to mention getting cargo to it while it's inflating its air bladder with helium, and how long it might take to in/deflate that same bladder. There is also the fact that going beyond that size actually makes mountains a hazard if it can't maneuver through ranges and the like, and while I have no hard data on this topic I suspect that the bigger it becomes, the larger the engines need to be to counter wind resistance. In other words, while the square cube law works in its advantage in terms of weight, it doesn't in terms of friction with the wind. To move such a craft through normal atmospheric pressures might take more engine power than you think. So, if Lockheed Martin are to be believed at least, then you're looking at around 800 feet in length being the maximum scale of an airship, although the precise reasons why they say that is the upper bound is something you'd have to ask them directly. [Answer] TBH I think the question is best answered by focusing on what your airship is meant to DO. For example: The size of modern ships aren't limited by what CAN be built, but rather by the size of the port facilities they want to visit, and by the Panama Canal. The latter wouldn't be relevant for an airship, but the former would. For example, you might be ABLE to build an airship five miles long, but it wouldn't be very practical either as a civilian or military vessel unless you had port facilities five miles long everywhere you wanted to go. [Answer] Other posts highlight issues with having to vent the lifting gas. One solution is a hybrid balloon, known as a Rozière, which has a non-heated lifting gas (e.g. helium) and a heated lifting gas (hot air). This design allows partial control of buoyancy via heating, whilst the bulk of buoyancy is provided by the lighter-than-air lifting gas, so fuel usage isn’t excessive. This might be relevant as you’re presumably looking to lift cargo with your huge airship. The design is apparently popular for extreme long duration flights (e.g. the Breitling Orbiter 3, and Fossett’s Spirit of Freedom, which circumnavigated the world). [Answer] I believe cluster ballooning can make an airship to get size. With redundancy comes stability in ballooning and size unlimited. Using a centered ballast to control altitude I believe a massive air ship could be used in so many ways from launching interplanetary rockets to living. I had asked a few questions in Space, Physics, Earth science and other SE sites about the limits of an airship. Also, the square inverse law to build an air ship this way using with balloons would be similar to building an upside down pyramid. [![enter image description here](https://i.stack.imgur.com/lsttA.jpg)](https://i.stack.imgur.com/lsttA.jpg) [![enter image description here](https://i.stack.imgur.com/CWYar.jpg)](https://i.stack.imgur.com/CWYar.jpg) ]
[Question] [ In a setting where portals can be opened between one location and another, Suppose you open a portal of area one square meter, with one end at the surface and the other end at the bottom of an ocean, three kilometers down, where the pressure is three hundred bar. Obviously a jet of water will come through the portal. What will be the speed of the jet? Equivalently, how many cubic meters per second will come through? [Answer] # Pressure from depth [Hydrostatic pressure](https://en.wikipedia.org/wiki/Hydrostatics#Hydrostatic_pressure) is the pressure felt due to the weight of things above it. The pressure at any depth in the ocean can be calculated by the equation for hydrostatic pressure: $$p - p\_0 = \rho gh.$$ Here, $p\_0$ is atmospheric pressure, and $p$ is pressure at the desired depth. The density of the fluid in the ocean is $\rho$, $g$ is the acceleration due to gravity, and $h$ is the height of the column of fluid. The density of water changes slightly with temperature, and even more slightly with pressure. We will assume a standard value of 1030 kg/m$^3$, which is accurate enough to three significant digits. $$\begin{align}p &= 1030\text{ kg/m}^3\cdot9.81\text{ m/s}^2\cdot3000\text{ m} + 101000\text{ Pa}\\ &=30.4 \text{ MPa}\end{align}$$ # Flow velocity from pressure [Bernoulli's equation](https://en.wikipedia.org/wiki/Bernoulli%27s_principle) governs incompressible flow of fluids at a low Mach number. Since our flow will be well below the speed of sound (as we'll see) and since we've already made an incompressibility assumption by using constant density in the last equation, we can use Bernoulli's equation here. Bernoulli's equation is $$c = \frac{v^2}{2} + gz + \frac{p}{\rho}$$ where $c$ is a constant, $v$ is the velocity of fluid flow, $z$ is elevation above reference, and $g$, $p$, and $\rho$ are as before. The constant can be factored out of the equation by rewriting the equation in terms of *total head*, which has units of meters. Before we re-write, we will cancel out $z$ as zero. You are asking for flow through a portal with no depth, there is no net elevation change between the pressure and low pressure zones. The energy head equation is $$H = \frac{p}{\rho g}+\frac{v^2}{2g}.$$ For the zero-velocity situation, i.e. on the ocean side of the portal, we set $$H = \frac{p\_O}{\rho g}.$$ On the atmosphere side of the portal, we set $$H = \frac{p\_a}{\rho g}+\frac{v^2}{2g}.$$ Now we can set these two quantities equal to each other to solve for the velocity of the fluid flowing through the portal. $$\begin{align}\frac{p\_O}{\rho g} &= \frac{p\_a}{\rho g} + \frac{v^2}{2g}\\ \frac{30400000\text{ Pa}}{1030\text{ kg/m}^3\cdot9.81\text{ m/s}^2} &= \frac{101000\text{ Pa}}{1030\text{ kg/m}^3\cdot9.81\text{ m/s}^2}+\frac{v^2}{2\cdot9.81\text{ m/s}^2}\\ v^2 &= 2\cdot9.81\cdot\left(\frac{304000000}{10100}-\frac{101000}{10100}\right)\text{ m}^2\text{/s}^2\\ v&= 243 \text{ m/s} \end{align}$$ # Volumetric flow from flow velocity Volumetric flow is expressd as $$\dot{V} = vA,$$ where $A$ is the area of the portal. Sinc $A = 1\text{ m}^2$, we have $$\dot{V} = 243 \text{ m}^3\text{/s}.$$ This is equivalent to the flow of the [Tiber river](https://en.wikipedia.org/wiki/Tiber) at Rome. [Answer] This is easy. Just use [Bernoulli equation](http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html). For such situation, it is like this water is falling from $3 \, \mathrm{km} .$ $$ V\_{\text{exit}} = \sqrt{2 H g} = \sqrt{2 \times 3000 \times 9.81} = 242.61 \, \frac{\mathrm{m}}{\mathrm{s}} $$ ]
[Question] [ There once existed a bird of massive size, aptly named [the Elephant bird](https://en.wikipedia.org/wiki/Elephant_bird). [![size comparison of Elephant Bird](https://i.stack.imgur.com/4lXQY.png)](https://i.stack.imgur.com/4lXQY.png) Over the course of history humanity rode several kinds of animals to war: horses being by a wide margin the most common. However, no large birds were ridden by ancient people. The still-living example of elephants birds, the ostrich, can run at speeds of up to 70 kph. A horse can travel only 48 kph. Thus, it is safe to assume that an elephant bird would also be faster. What's more, an ostrich's kick has been known to be able to kill a lion - and the ostrich is the smaller, weaker version of the Elephant Bird. Modern people have proved that [ostrich riding](https://www.youtube.com/watch?v=R_AaEpqtgiQ) is possible. So I was wondering, could Elephant Birds be domesticated and/or trained? If so, would they be feasible as warmounts? [Answer] I think yes...but a few considerations. I'd almost refer to an old answer about using buffalo as heavy cavalry, I'll link that after the post. First to consider is the relationship with man that birds have compared to horses. Somewhere along the way in the domesticated horse, a relationship with humans became core to it...they seek us and our companionship. This makes riding them (even untrained) a much easier prospect. Ostriches...I've dealt with domesticated birds before and even then they are flighty creatures at best. But lets say whatever people this is has domesticated the ostrich to the point of the horse just to overcome that. I also have this feeling that they aren't exactly bright animals and are just as likely to start feeding on the ground as they are to take a command from something riding it. Ostriches are ultimately birds and have a different skeletal make-up that we do. Even a full grown Ostrich is lucky to hit 120 kilo's...compared to a horse, this is exceedingly light. This does limit the effectiveness of the ostrich mounted unit...part of why a cavalry charge is so effective is you are throwing the weight of a 300kg + horse at the weight of a human...this isn't quite so in the ostrich case. So as far as using these as head on charging troops, I think you are pretty limited. Ostriches are also quite a bit more fragile than a horse...the long neck is a target just waiting to be hit by whatever these troops are fighting. Birds bones are a little more fragile as well, so I doubt this ostrich could really take a hit if and when it happened. But that isn't the question...question was regarding light cavalry. Light cav are primarily used for chasing down routing opponents and hitting ranged troops (such as archers) as quickly as possible. From that standpoint, it seems these could work. However, I suspect the best use of these would be to combine the Mongols golden horde technique with the Ostrich...bird mounted archers. They never fully engage troops (gets around the fragile and flighty/spooked portion) and use their mobility to avoid direct combat. Assuming they are as fast as the questions states and can take orders from a rider (remember the rider needs both hands for the bow), they could actually be quite effective. Even more-so if the opponents light cavalry couldn't chase them down. [Answer] Is it plausible as a mount? Yes. It's already been pointed out that ostriches are viable mounts, and there are even ostrich races. However, it's irresponsible to assume or assert that the elephant bird would be faster than a horse. I have seen no indication we know how fast they were, so I can only point out what is comparatively true. The more mass, the more energy it takes to move. This would mean that, like the elephant, it could be faster than humans, but won't win a race with a horse. It takes more 'horse power' to make a larger beast move, and more energy to sustain it. Not to mention we know little about these creatures. Would they take to (semi-)domestication? Would they be worth the effort to encourage us to continue trying? Would they need more care and sustenance than horses and/or elephants and/or ostriches? In other words, is it worth the investment? Would their top sprinting speed be worth it? Would they be trainable enough to selectively breed them for endurance, a would be needed in a war mount? Arguably, any creature large enough to support the weight of a ride (in armour) is a viable war-time mount. All it takes is time to selectively breed them for the most describable traits, and training them to be able to handle the strain and stress of it battle. So the question, really, is what animal is worth the investment to you? [Answer] **Light cavalry, no. Domestication...maybe?** [![elephant bird leg](https://i.stack.imgur.com/FIbqB.jpg)](https://i.stack.imgur.com/FIbqB.jpg) This is an elephant bird leg, with an ostrich to the right for comparison. Elephant bird legs are *thick*. They definitely weren't as fast as ostriches, overall they seem to have had a lot of endurance but weren't very fast. They might work better as draft horse analogues (and horses in war were often used to haul cannons and artillery), and might even be useable for heavy cavalry in that case. There is a potentially bigger problem. [Elephant birds have terrible eyesight, and were likely nocturnal](https://earthsky.org/earth/giant-extinct-flightless-elephant-birds-nocturnal-possibly-blind). I wouldn't be surprised if this finding is modified in the future (their eyes seem to be decently-sized), but for now it seems they were likely primarily active at night. This might make them bad war mounts because they can't see where they are going in the daytime (alternatively, it might make them better war mounts because they are less likely to get spooked by motion). Ancient Malagasy people used elephant bird eggs (and even used fossilized ones) as pots and storage devices, which provies a good initial impetus for domestication and keeping them around, and they would make good pack animals if nothing else. So it's possible they could be domesticated as long as there isn't some as-yet undiscovered behavior that makes them unsuitable for domestication. **As a bonus**[, there is a giant extinct elephant bird-sized maybe-ostrich relative from Eurasia that does seem to have been a fast runner based on its limb bones.](https://www.sciencedaily.com/releases/2019/06/190626200313.htm) ]
[Question] [ This began life as a much broader question on the site but I'm attempting to parcel it out as smaller topics to make it more digestible: I am trying to find ways, as the title suggests, to combine modern low-tech ideas with the life of medieval serfs, peasants, commoners, etc. **Specifically, modern innovations that would help improve their homes that can be replicated in their time/state without the need of most modern technology (computers, cell-phones, electricity, automobiles, etc.).** The idea is to for them to give them ways to "work smarter" instead of necessarily "harder." *The examples I've been using are: imagine a group of modern people leaving society to start their own technologically-free one on a virgin world exactly like Earth, swearing off any modern methods that can't be reproduced without technology. Or, if it works better, imagine time-travelers going back into time to the Middle Ages and giving medieval serfs modern techniques, tools, and ideas they could use and replicate in their own time. Or, if you like, how foreign aid is helping to improve third-world countries improve their quality of life with these low-tech innovations. If any of those help, use them (I will divulge more if I need to).* **I've been looking into a lot of different areas for this, but I am looking to see how a commoner's home - their house and the acre or so that home occupies - could be improved with these kinds of modern (but low tech) innovations.** I've looked into areas like the modern homesteading movement, green and eco-friendly living, foreign aid efforts, survivalist and apocalypse training, etc.; and into specific innovations like rocket stoves, powerless refrigeration, rainwater capture, air wells, low-tech greenhouses, permaculture, etc. There are plenty of things... Personally, I see a lot of villages being made of self-sustained acres of gardens and stables, on the same acre(s) the houses occupy. These gardens are filled with plants that grow well next to each other given whatever climate the village is in, and give the villagers both something to feed their families and sell for personal profit (if not going straight to the local lord). The houses themselves are made of something like cob or rammed earth, with some form of insulation (straw, or some extra layer of available material), with windows that have some sort of sealing to keep out the cold. They have cisterns to catch rainwater, and/or an alternative like an air well to catch condensation. They have primitive means of filtering water, if they need it, using charcoal and layers of sand, etc. They have something like a potted refrigerator, or maybe a below-ground cellar that offers powerless food storage for months at a time. They have something akin to composting toilets so that they aren't simply dumping their waste into the streets or nearby bodies of water, using it instead as fertilizer, etc. Meat is more readily available, in the form of animals and some larger livestock-types, which they can keep in stables that are themselves insulated from the elements and don't need to be brought into the house just to make it through the winter. I could go on and on... **...having said that, that's an ideal, pie-in-the-sky scenario I'm not married to. If it doesn't work, it doesn't work. That's why I'm waiting on the discussion. If that gives you a better idea of what I'm aiming for, though, so be it.** ***EDIT BY BSIDESWIPED***: Given that the question is still kind of broad historically (an oversight I always manage to forget, since it's a topic I'm not especially learned in yet), let me try to refine the question further. I would say, if I had to choose, **at the most I'd like to keep things somewhere between the post-medieval era and the Elizabethan era** (if I've got my eras right). Much further than that and it starts muddling my narrative. I hope that helps. [Answer] Some of the things they could do are modern takes on ancient techniques. For instance crop rotation and allowing the land to rest once in a while. We know that if you plant the same crop year after year you deplete the soil of nutrients and the plants don't do as well. So you rotate the crops, planting something that puts nutrients back into the soil. Another problem was plow pan, where after a period of plowing the field year after year, the soil below a certain depth would get compacted, keeping the roots from going deep. [![plow pan](https://i.stack.imgur.com/u217Q.jpg)](https://i.stack.imgur.com/u217Q.jpg) I remember reading that it wasn't until the 1800's when they figured this out and how to break it up. For the time traveler back to the middle ages, germ theory would be a huge breakthrough, and that just boiling your water, washing your hands, and keeping wounds clean would save lives. Depending on the time period, a lot of our more modern metallurgy technology could be usable back then, especially some of the really difficult stuff like aluminum. Aluminum is very plentiful on earth, but does not exist in a pure elemental state like iron and so has to be extracted from aluminum salts which was a very difficult process for a long time. For a while aluminum was worth a lot more than gold. (side note, when traveling back to the middle ages, take aluminum ingots) Quite a lot of our modern chemistry could be duplicated with very simple equipment, allowing for much earlier development of plastics, explosives, medicines, etc. The ideas are the hard part; the inspiration to mix this with that. Once you have the knowledge, you can bootstrap the technology by making tools to make the tools you need to make the technology. And a lot of times you can fudge that with fairly simple things. Watch a couple episodes of MacGyver to see what I mean. Edit: Other simple things that mostly weren't thought of until later, or at least were not common: * Insulation (keeping the warm air where you want it) * Something like the Franklin Stove or Potbelly stove, to help heat homes with less smoke. * [Biology and basic medicine](https://en.wikipedia.org/wiki/History_of_medicine#19th_century:_Rise_of_modern_medicine) (expanding on germ theory), since a lot of the workings of the human body was super mysterious for a long time. Edit 2: This is more for a time traveler than for a colony on a new world, but one simple thing that would be very useful is a map. Especially a geological survey map where the various minerals are located. Knowing where to find deposits of copper, iron, nickle, chromite, oil, etc. would be really useful for metallurgy since some of the harder forms of steel need various mixtures of minerals to make. Even mines that are played out in the present would still exist in the past, and could be used. (at this point history has been changed so much you might as well go all in). [Answer] One of the largest problems in the pre industrial era was the ability to grow and preserve enough crops to ensure survival in the "lean years". Pre modern agriculture was horribly inefficient, and even in good harvest years, it was difficult to store enough food to ensurer that everyone would have enough to eat through the winter, much less the "seven lean years". So the first improvement would be to teach more efficient agricultural techniques to increase the amount of food that could be raised per hectare. This would include ideas like multi cropping (growing multiple types of plants in the same field at the same time), using mutually beneficial crops (legumes to fix nitrogen in the soil for the next year's crop, planting species of plants which deter pests in the fields are two common examples), proper water and soil management to prevent topsoil from eroding away and going to a more vegetarian diet to get more bang for your buck (plants typically take 1/10 of the available solar energy, while cows, goats etc take 1/10 of the energy that the plants absorb. Being a carnivore is an exercise in diminishing returns). The next huge step would be efficient food storage. Sealed containers that can keep pests out of the stored food is perhaps the best possible solution given the available technology, although iceboxes could be introduced on a limited basis as well. More modern techniques to dry foodstuffs for longterm storage would also be a great improvement to ensure long term storage of food. Ensuring people have enough to eat, and can store food for long periods of time will provide a solid foundation to jumpstart any social or economic improvements. [Answer] Lots of good answers from other people, so I'll add: **reducing child mortality** and **providing reliable contraception**. If you explain to the medieval/Elizabethan people: 1. What germs and viruses are. 2. How particular diseases are transmitted (cholera is fecal contaminated water, measles is coughing and sneezing) 3. Simple hygiene techniques like boiling drinking water, sterilising surgical instruments, washing your hands after you go to the loo, sane quarantine procedures (i.e. NOT walling people up in their homes), and decent sewage systems. 4. Treatments for some of the diseases (not sure if you want the tech level for vaccination or production of antibiotics). Then more of their children will survive to adulthood. This will make them happy, and provide more manpower for agriculture, for various crafts and trades, etc. Downside... it will also cause a population explosion. So in tandem with that healthcare improvement, introduce them to contraception. The lowest tech method which is reliable is probably the IUD. Obviously plastic, hormone impregnated ones are out, but you could make copper ones (IIRC the Romans used copper rings as IUDs). And you'd know to sterilise the IUD before insertion, and could give the women a list of the side effects (or get your doctors to watch out for them). Meanwhile, you have the ethical dilemma of whether or not to tell them where the Americas are and let Eurasian epidemic diseases wreak havoc, or to nip across there yourself and say *"Hi Native Americans - I'll swap you a vaccination programme for your potatoes, maize, chilis, tomatoes and turkeys"*. [Answer] This is a broad ranging question, I will try to be brief; that said, I would hope that the question of time-travel colonization, or of a 'virgin Earth' would not be a goal, as our own history shows when two civilizations meet, the technologically inferior one usually suffers greatly. May of the questions you've asked, and technologies suggested are in place and working well, in one of Earth's little known secrets, called Arcosanti. Paolo Soleri conceived of things much as you did, with the benefits of modern and antiquity living together, in what he described as an 'Arcology' ( See [HTTP://arcosanti.org](http://arcosanti.org)). His concepts included a self-sustenance and environmentally neutral presence with groups of families maintaining and working the project. Arcosanti is located in the desert, north of Phoenix, Arizona. This may or may not supply you with the answers you need, but I feel Soleri's models and ideas may be an eye-opening moment for the imagination. Good Luck !! "... If you believe that the human spirit deserves and is capable of better than it has gotten environmentally ... if you believe in the human spirit at all, go to the Corcoran ... 'The Architectural Vision of Paolo Soleri' is an important and beautiful show ... His philosophical and environmental perceptions offer a sudden, stunning pertinence for today. He does not need the current bandwagon of despair. He has been preaching environment and ecology for a long time ... He has been the prophet in the desert and we have not been listening." —Ada Louise Huxtable, New York Times,1970 ]
[Question] [ A [Golem](https://en.wikipedia.org/wiki/Golem) is a creature of Jewish lore, they are living creature created by inanimate objects like clay, stone, hay or wood. They obey their master and will follow their orders. Creating a true golem is impossible both through man made creation and evolution. The question is, how close can I get to the design of a golem? * They need to seem to be built out of inanimate objects to the human eye. These can be any objects that appear in the golem habitat. * They need to be roughly similar in shape to a human. * They need to follow or obey another creature. (I imagine symbiosis can be used here.) A list of all of the Anatomically Correct questions can be found here [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) [Answer] The easy one here is, make a robot! Robots are pretty much the 21st Century realization of the Golem. It mindlessly performs tasks set by its master. It is also similar to Frankenstein, where he builds a 'living' thing out of the body parts of the dead. Unlike many of the other 'anatomically correct' questions, in the Golem mythology it is MADE by people. So a robot can be made to look the part and even be fitted with biological or inanimate parts to meet any appearance needed. Just as a side note we have [Decorator Crabs](https://en.wikipedia.org/wiki/Decorator_crab), which use parts of their environment to camouflage themselves, sometimes looking the rocks or other inanimate items in order to hide. [Answer] Something that I recall about golems is that they're supposed to be virtually indestructible. Basically, the only way you can kill it is to destroy the magic that gives it life, otherwise it'll never stop. This makes me think of a rhinoceros. Rhinos are covered in armor plating that might, to some, look like solid rock. Plus, all sorts of animals like rhinos love to roll around in mud in order to keep cool. A sufficiently dirty rhinocerous may look like it really is made up of mud and stone (at least to people who don't think that's preposterous). As for getting it to be man-shaped, well, rhinos are mammals, so they've got a lot more in common with us than most other animals. And they have a long evolutionary history, it's not too much of a leap to say that a distant ancestor of a rhino split off to develop a primate-like physiology while retaining its plating and desire for a thick coating of mud. As for the desire to follow a leader, rhinos are herd animals, so they should be relatively easy to domesticate. If your golems are shaped like us, it may be even easier to imprint onto them at birth, so they grow up thinking you're the alpha. Just to be safe, you'll probably want to get rid of the reproductive organs as quickly as possible so they don't get aggressive during mating season. [Answer] # Make them a plant! As the plant evolves, it is known to the "master" species as a valuable tool, and thus the humans evolve into a symbiotic relationship with it, providing water, protection, and other such. Over time, the hardy "golem" becomes massively useful to humans, learning how to do more complex tasks and even understand speech in a mixture of domestication and symbiotic evolution. Eventually they begin to even take on human traits and shape to better serve their needed purposes. Part of this change includes them requiring less and less from the humans, trained in mind to serve the masters who no longer need to provide for them. Now the humans are parasites of a sort, admittedly, but on the upside, the golems are mindless and don't care. As for the anatomy itself of a clay-like structure, they would probably find carrying fertile soil around to be a very useful ability. They also learn to carry stones, wood, and grit to protect their innards. When they need a recharge, they just sprout some leaves, which die and eventually look like collected "stuff." ]
[Question] [ I've always liked the idea of [scythes](https://en.wikipedia.org/wiki/Scythe). Their connotation of death and reaping is always satisfying. But they're also a polearm, and that could make for some interesting martial feats. But nearly every discussion I see claims they would be useless as a weapon, due to the poor length/area of cutting edge, inward-facing blade, etc. *Without moving the curved blade and/or its position* (unless it shifts back and forth), what other problems does a scythe pose, how can I write them away, and most of all, **what benefits would a "traditional"-esque scythe have in combat?** [Answer] **TL;DR: It can and has been done, although not with the exact same scythe you'd use for grass or wheat.** Well, people *have* used scythes (or more accurately, sickles) as weapons in combat. Most notable example is a [kama](https://en.wikipedia.org/wiki/Kama_(weapon)), and a [khopesh](https://en.wikipedia.org/wiki/Khopesh) is also superficially similar, so perhaps you could have those and say they evolved from sickles. The reason for use of sickles rather than scythes is that a scythe is a relatively modern thing; the long blade needed to make one work could not be manufactured reliably before steel became widely available. That's why people used shorter sickles instead, and adapted them as weapons. You already seem to have a good idea of the disadvantages, but consider that a battle-scythe would probably be quite unlike a field-scythe (much like a [battleaxe](http://img1.rajce.idnes.cz/d0103/6/6892/6892173_a4d89650acd06382e668658d856e2134/images/Fotografie-0088.jpg) is quite different from a [woodsman's axe](http://www.aaaobchod.cz/images/large/MB/254090006764_0_LRG.jpg)). You could definitely add a spike for stabbing, make the blade shorter and thicker (and hence more durable), but at this point it seems to me we are arriving at an elongated halberd. Which, on the other hand, has a good service record, so you might just design a halberd differently and call it a scythe. As for the advantages, the form of the weapon gives you a pretty good grip for slashing, and the perpendicular blade is good for hooking (much like and axe or halberd would be used), which is useful when facing people with shields. But the main advantage is that in a mediaeval/fantasy setting, you can easily recruit a lot of people who are *already trained with their weapons* (ie. peasant farmers), if you can figure out a simple drill to let them transition from a field scythe to your battle-scythe. This is an important consideration, which has in practice led to development of [war flails](https://en.wikipedia.org/wiki/Flail), [voulges](https://en.wikipedia.org/wiki/Voulge) and [war scythes](https://en.wikipedia.org/wiki/War_scythe), all of which have been used to great effect in warfare (the above three notably in the [Hussite rebellions](https://en.wikipedia.org/wiki/Hussite_Wars), which were essentialy a popular movement and defeated five separate crusades called against them). [Answer] The Scythe might need a few modifications for any kind of combat. the biggest on would be to have a longer collar attaching it to the handle, otherwise, it will likely be cut off after a few blocks or perrys. giving the collar a little edge wouldn't hurt either.[![enter image description here](https://i.stack.imgur.com/JJV6c.jpg)](https://i.stack.imgur.com/JJV6c.jpg), In a single combat situation, it might be used to delimb an opponent, but I suspect the scythe wielder would have to be much more proficient than their opponent. If the scythe is a symbol of death, and the wielders dress the part, they may be able to intimidate their opponents into mistakes. **The one situation that I could see the scythe being a possible devastating weapon would be when attacking a shield wall like the Romans had, the long handle could keep you out of range of the gladius and the long 90 degree blade could reach down over the shield wounding the holder and possibly yanking the shield out of their hands and the wall** [Answer] Since you're giving me "in a (slightly) less-realistic world?" to work with I feel like a couple of potential options present themselves. For starters it's possible that an entire form of martial arts has been developed around the use of the scythe (and possibly other farming implements) as a means of dealing with frequent raids or attacks in a largely agricultural nation. As such no extra weapons are required citizens don't have to "beat swords back to plowshares" they can literally just keep using the same tools for farming and combat. The other would be something you mention about the blade shifting back and forth. Simple spring loaded locks near the handle could allow the blade to snap into a combat scythe shape at the push of a trigger. This would take it from farm mode to war mode in an instant; and then properly trained peasants can form something like pike men lines to stop cavalry or the like. [Answer] I may be a little late, but I've actually designed a prototype for a scythe which I believe to be usable in combat. First I've reduced its total length to 56 inches and increased it's blade head side to 30 inches. Next I decided to add a bayonet-type thing to the other side of the head to allow stabbing and protect the shaft a little, I've also added a spearhead at the bottom of the shaft. To reduce the weight of the weapon a little I made the shaft out of a kind of fiberglass reinforced nylon which is lighter and more durable than wood. Finally I added a semi-sheath for the blunt side of the blade. If you see any issue with my design please tell me. Hope I answered your question. [Answer] The tool is in fact a well-refined design *for its purpose*. In [*Midnight at rhe Well of Souls*](https://en.m.wikipedia.org/wiki/Midnight_at_the_Well_of_Souls), one species is described as feirce fighters that resemble blades of grass! So, the scythe would be the right weapon in this situation, and it occorred in a book that sold a million copies, so it’s reasonable to have such an enemy it seems. [Answer] I would say that a good way would be to slightly change the make up of the weapon, but leave it still recognizable as a scythe. one of the biggest problems with scythes as weapons is the fact that it's only edged on the inside of the blade and not the outside, so I would say make the blade a tad thicker and edge it on both sides of the blade. Another thing is that the weapon is unwieldy and off balance, so properly setting a center of gravity into the staff by some type of reinforcement would be necessary. Adding some type of counterweight on the bottom of the blade could actually double as a clubbing device as well. Last but not least you would need the proper fighting style, as a scythe is again very unwieldy the style of fighting would inevitably be very momentum based, a tad similar to a bo staff's fighting style, a lot of fancy footwork and twirling and spinning to build up momentum and keep yourself protected, as well as enabling more than one attack in a single push, allowing you to twist the blade around into multiple strikes. [Answer] A bit late, but maybe making the pole arm out of a strong, flexible metal would work. Allowing the scythes cutting edge to bend outward creating a better angle of attack. It would also catch someone off guard if they weren't prepared for it. [Answer] In a way a scythe having a strong pole is what really matters scythes used in combat. It can be used for a lot of acrobatic moves due to the long arm and curved blade, having one side weighted makes it better for spinning in a way because the weight is distributed to one side, so the scythe can be spun blade or pole first. One thing I’ve noticed is a lot of scythe users in shows or games favor aerial strikes or wide swinging slashes [Answer] Forward curved weapons come with a several advantages and disadvantages to consider: **Advantages:** * There is a kinesiological advantage to weapons that have an impact point forward and curved slightly inward from the handle/hilt. Weapons that do this strike while your stronger upper body muscles are are still engaged and your weaker wrist is still locked. This leads to a more powerful strike. You see this for example in the design of kukris and khopeshe. * Makes the weapon distal-heavy which also leads to a more powerful strike. * Forward curved weapons can reach around shields making them especially effective against enemies who prefer shields over heavy armor. * This can also result in strikes to your opponents back side which is often less well armored. **Disadvantages:** * Not as good for thrusting as a straight blade. * Distal heavy weapons have more inertia which forces you to commit more to your strikes. This leave you vulnerable as you over extend yourself with each missed strike. * Distal heavy weapons are also much harder to parry with. * Forward curved weapons are very unforgiving when it comes to edge alignment meaning it takes more skill and control to get a clean cut. * Weapons which extreme curvatures are more likely to run into issues with having enough room to maneuver your weapon in the tight confines of a battle formation. * The weapon has a small threat range meaning you need to be at exactly the right distance from your opponent to be able to successfully hit them. Many historical weapons could answer your question which by either use blades similar to the scythe but on shorter handles such as the the Dacian Falx or the Gallic Sicle, or long scythe like handles, but changed the profile of the blade like the war scythe, the bill, or the warpick. **So, why not both?** The design of the scythe is too specialized at delivering a powerful blow at the expense of other features. As a polearm, it is very unforgiving in terms of over or under shooting your opponent (which is why the bill and war scythe are shaped as they are) and even if you could land a hit, the blade is poorly designed to handle that much force smartly. Either you hit something soft and you bury your blade so deep in your opponent it gets stuck (solved by using a bec-de-corbin or poleaxe) or you hit heavy armor and the blade bends instead of punching through (solved by using a warpick). Shortening the handle means you can use the weapon while locking shields with an opponent. While a scythe would be too long to strike at this range, once you lock shields, you can control distance meaning that a narrow threat profile can be mitigated. The shorter handle minimizes your other disadvantages related to poor balance by lightning the weapon and bringing the weight closer in to your hand, but it also takes full advantage of the good aspects of a distal weighted, forward curved weapon by maximizing the force you can get out of such a small weapon. --- So that is the history lesson and the reasons why not to militarize a scythe, but that is not your question. I believe you could make it a viable battlefield weapon, but it would require just the right mix of added features and tactics. 1. The Greeks made their spears so long that they ran into serious problems with too much distal weight as well; so, instead of making the front of their weapon lighter, they made the back heavier with a **sauroter**: A heavy bronze spike. By adding a counter weight to the back of a scythe, you give it better balance making it easier to manipulate the head of the weapon quickly. This means you will have more control to bring the blade down when and where you need it, and more importantly stop and redirect it as needed. It could also be used as a secondary weapon if your enemy closes into a closer melee. 2. Change which side the edge is on. The curvature of the scythe allows you to do effective draw cuts with it; so, if you undershoot your enemy you can just push in and slice with the front blade like a sabre. Or, if you overshoot, you can still pull it back to stab them with the weapon's tip. 3. Furthermore, the broad blades can be used just like a shield wall to control distance. If you plant your first line of scythes using the sauroter to brace the impact, you could stop a charge short of being in close quarters of you, then your second line could reach over the shields of your enemies to similar effect as a Dacian Falx, but without having to get in so close that you are also at risk from enemy swords. ]
[Question] [ I'm trying to create demons that aren't just raging murderers, as much as they're enslaved to their disposition they're not completely conquered by it, with a sense of humanity and reason crawling under their skin. I also want several polar groups representing different fears like rejection, lack of control, being chased etc, but is that contradictory to depth, would they have a mixture with more dominant dispositions complimented by weaker flaws or a harmony of flaws? --- * If you have characters founded on extremely negative traits how do you humanize them? * Can characters have depth if their flaws revolve around a single extreme negative trait, like jealousy or greed? Or does there need to be a mixture? * Is it plausible for a community to be driven in unison by a singular internal negative trait? For example, imagine if there is a village that is always angry, how do the people coexist with each other? If that's possible, could they coexist with other villages that are always envious, greedy or lustful? --- My understanding from the answers given are as follows: * Demons take the extreme personification of a trait, naturally revolving around it. However, What is considered a positive or negative trait is down to its application, utility and perception. As long as a trait does more good than harm the community could potentially embrace it. * Traits can also be accepted as a natural byproduct of circumstance, their outlook on life could rationalize solutions to their tribulations. * Setting up empathetic connections in back story allows the reader to understand their perspective: motivations, circumstance, choice e.g. "righteous intent leading to accidental ruin", which ties into a conflict of interests or justification of actions as a lesser of two evils. * Despite Vulcan's polar emphasis on logic, Spock could not escape his human traits, largely considered flaws by his people. It's not always apparent, yet makes an appearance every now and then when circumstances stimulate it. * As Vulcan's emphasize logic to better achieve their goals, so could demons use the 7 deadly sins to their own ends, where their justifications could validate its plausibility. [Answer] It's not the easiest thing to resolve...Demons most often take the form of a personification of a specific feeling or trait in a person, and therefore their entire being revolves around the feeling/trait that they represent. A 'negative trait' is ultimately the perception of said trait...it is negative because we as a collective whole agree it is negative, not because it inherently is negative. For example, most humans will readily squish/kill/maim a cockroach without second thought...an act to us that most of us consider in no way evil, except from the cockroaches point of view in which case we're the most evil demons around. If this Demon viewed humanity in a similar method as a human views a cockroach, then from the Demon's perspective he/she/it/all really isn't "negative" or preforming negative acts...the Demon is just doing what the other demon's consider fully acceptable. Society for us generally stresses a trait over another one and defines for us what we consider positive vs negative. If for whatever reason, anger wasn't considered negative but was considered a positive thing that drives and motivates us then you can have a trait which today's humans may consider negative be actively promoted as a good thing within this society. If you take it from that perspective...then the negative trait is simply one trait that is emphasized over the others. Borrow the Star Trek reference...Vulcans value logic over all other traits. This doesn't mean that they aren't influenced by other traits, it simply means they put an extreme emphasis on that trait over others. It's actually impressive how well we can cherry pick these positive vs negative interpretations, taking some as is and challenging others. When it comes down to it, how big of a difference is there between a pig and a dog? Why do we allow ourselves to kill and eat one, but not the other (to the point where much of society considers harm to a dog to be on par with harm to a human, and verbalize this loudly while chewing on bacon). Answer to the questions more directly: > > If you have characters founded on extremely negative traits how do you humanize them? > > > The extreme negative trait is in their eyes is considered extremely natural and in no way negative...in fact it's likely viewed as a positive trait to continue to work on. Does this mean there is no other traits? Of course not, it's simply stressing this trait that humanity considers negative today as a positive trait they need to work on. Moreover, despite what society says, each individual can choose their own. > > Can characters have depth if their flaws revolve around a single extreme negative trait, like jealousy or greed? Or does there need to be a mixture? > > > No more than Spock was capable of being a being of pure logic...despite his best efforts and outright denial, the other traits were there. > > Is it plausible for a community to be driven in unison by a singular internal negative trait? > > > Entirely...the society simply doesn't view that trait as negative and puts a huge level of stress on it. [Answer] Interesting question...so humans in my experience are complicated creatures. To be human, and believably so, you require a certain level of complexity. A character that demonstrates only a single characteristic cannot be believably human, just think of a character on a tv show...audiences come to like a certain aspect of the character and then writers abuse that single aspect to the point the character can lose what made them relatable in the first place. > > Edit #1: If you have characters founded on extremely negative traits > how do you humanize them? > > > This is actually pretty easy. Look back at history and pick some of the worst, Hitler, Stalin, Pol Pot...they were certainly human. Giving characters a background, experiences and situation that explains their wicked ways humanizes them. > > Edit #2: Can characters have depth if their flaws revolve around a > single extreme negative trait, like jealousy or greed? Or does there > need to be a mixture? > > > So no, a character with a single trait around which their personality revolves is not realistic, at least not when trying to humanize them. > > Edit #3: Is it plausible for a community to be driven in unison by a > singular internal negative trait? > > > Keeping my response to question #2 in mind, it follows that you also cannot have a community that is tied to a single trait [Answer] I'll address your edits, as they provide the clearest picture of the questions you want answered. > > If you have characters founded on extremely negative traits how do you humanize them? > > > This probably would be a better question to ask on the Writers exchange, but James has the right of it. Give your evil character a background, show how they acquired their outlook on life and why they are evil. [This blog post](http://thomasaknight.com/blog/36/) discusses how to humanize a villain. > > Can characters have depth if their flaws revolve around a single extreme negative trait, like jealousy or greed? Or does there need to be a mixture? > > > I have to agree with James on this one as well. A relatable character can't have just one flaw, or one class of flaws. You need variety. Life experience introduces a great many flaws in all of us, but they don't have to be inherently bad or evil. The desire to protect can be a flaw if it leads a character to not want to put others in harm's way, even if doing so is the only way to overcome the antagonist. Protection to the extreme is actually a fairly common trope. > > Is it plausible for a community to be driven in unison by a singular internal negative trait? > > > This is where I have to disagree with James. The individuals who comprise any given community cannot be founded on and possess only one characteristic, but the *community*, as a whole, can. One collection of peoples can be adamant about the utter inferiority of another collection of peoples and seek to destroy them. Here, the community is founded on rage, but that rage is directed towards an external group, which allows the community to remain stable. Envy introduces another option for a community: resources. Suppose Group A has access to lush, fertile land that has been carefully cultivated for generations and their neighbors, Group B, has squandered the riches of their land and the community is now destitute and famished. Group B clearly wants what Group A has. The community is founded on envy, but that envy is directed, once again, towards an external group, allowing the community to remain stable. [Answer] One of the ways to approach this may be to imagine yourself in the demon's shoes, it's very hard to give depth to someone when you always think of it as very alien. So take humans, they often have some depth and have cultural differences and personalities, but most of them are OK with killing animals for food. Now if your demons need or really like to eat souls or some such, it puts them in conflict with humans and they would seem pretty evil from our perspective, but they can have a society and belief systems as complex and diverse as we do. Some demons can be sadistic psychopaths that like to kill things and soul eating is just gravy, some might do it for the thrill of the hunt because their home life is bland and things are getting stressful at the office. Some might be OK with certain humans but just really like those souls. So they can be "evil" but just as complicated and deep as humans [Answer] Expanding upon the idea of giving your villains a backstory here, since I can't comment yet and this may contribute enough to warrant being an "answer" in itself. But if you want to humanize your demons, you could create a world/universe in which demons began as humans and perhaps some even retain looks similar to or with components of their original human form. Angels, for instance, are often portrayed as "beautiful" humans with glowing wings. There's no reason a demon couldn't be human-esque as well, but with attributes that lend themselves visually toward whatever characteristic it is that motivates them. Perhaps their eyes glow in a way so palpable that it openly portrays fury, lust, or greed. If you start them as a human, and have other characters, perhaps demons willing or bound to work alongside scholars or wizards or whatever you have who can explain their origins. Maybe a demon bound by vengeance was originally a prince or king known to rule with a kind heart. However, upon being trapped and forced to watch a slow but inevitable slaughter and ruin wash over his land as he could do nothing to stop it (a bit cliche but it gets the point across) becomes so compelled with the need to avenge the atrocity that he himself crosses the line, taking it out on anything his now perverted sense of justice defines as "the enemy". You could even have demons who work as "recruiters", intentionally creating these scenarios to raise up new hellspawn. [Answer] The easiest way I have found for this sort of task is to treat people as a gestalt, a structured group whose whole is different from the simple sum of its parts (which is not a difficult reach). This points out that once you're inside their "mind," it isn't homogenous. You don't need to have a uniform perfusion of perversity tainting their mind; you can have regions. From there, I find it effective to think of the mind in terms of an inside and an outside. On the outside, there is a need to respond quickly to constantly changing situations. Reflexes sit on the outside. As you move towards the center, you get a more and more complete situational image because you can take the time to process more of the information. However, you also get a more abstract image because you simply don't have the bandwidth to soak up every single sensory neuron's data and forward it (it'd drive you insane). So we have a archetypal "mind:" a region of fast-reacting reflexes on the outside which don't have a full view of the world, but they truly understand their little corner of it. In the middle regions, you have slower-reacting thought processes which take the time to process the entire world with more and more abstraction, feeding that information to the exterior (the sense of "the hairs raising on the back of your neck" would be an example of interior abstract models telling the periphery "you better get extra sensitive, we think the world is really dangerous and we need super-jumpy reflexes"). With this model, we can describe a demon with a negative trait deep in the middle of the abstract region of the mind (which is why the negative trait is usually some abstract concept like "gluttony"). Left unchecked, this negative trait will simply spread, completely consuming them and destroying any shred of humanity. That's the boring case, so let's assume they're not unchecked. Let's let our demon literally do war with its negative trait. This process would not be simple. If the negative trait gets too close to the "center" of the mind, it would take over the most abstract and most fundamental concepts behind the demon's self, so the demon has to keep the negative trait away from the center. However, if the negative trait manages to get close to the exterior, it gets in a position to physically command the body because it can effectively cast a shadow over those exterior sections, preventing them from benefiting from the wisdom emanating from the central regions. From there, it would be easy to manipulate those small fast-but-not-so-smart regions of the mind to do the negative trait's bidding. Accordingly, the best the demon can do is to hold their negative trait in a sort of holding pattern between the extremes, trying not to let it control its body, but trying not to lose control of its self by letting the negative trait dive into its center. The negative trait would have to orbit in the middle, seeking ways to poke and prod either in or out. In effect, the demon now has an internal demon for itself. Every now and then, the demon would make a mistake, letting the negative trait dive too deep towards the self. The demon would have to rapidly pay attention to this, hardening itself and directing awareness away from the periphery. At this time, the negative trait could easily give up its quest for the center, take substantial control of the body, and wreak havoc before the demon's self can wrestle control back. This should be enough of a model to answer your questions, so lets address them in order > > I also want several polar groups representing different fears like > rejection, lack of control, being chased etc, but is that > contradictory to depth, would they have a mixture with more dominant > dispositions complimented by weaker flaws or a harmony of flaws? > > > I think any individual, demon or not, facing a great flaw, would develop an inherent natural set of lesser flaws to help it out. A real life example would be the poor father with no self control developing a drinking problem to try to drown his sorrows. > > Edit #1: If you have characters founded on extremely negative traits > how do you humanize them? > > > Show the struggle. Self awareness of one's negative traits and the effort to overcome them shows humanity, even in the worst. The TV show Scandal had an excellent example of this in the form of a character that had gotten addicted to torturing people, and was basically putting himself through the worst 12 step program any human could ever deal with. In one horrible moment, where he had to return to torture, his words were something to the sense of "I don't want to torture you. I fear I would enjoy it too much, and I have spent too long try to get away from that black abyss. However, this is very important. You are going to have to learn a lesson. So, I will enjoy it, as best as I can. I am sorry" > > Edit #2: Can characters have depth if their flaws revolve around a > single extreme negative trait, like jealousy or greed? Or does there > need to be a mixture? > > > As long as the negative trait is not in a boring holding pattern, there's plenty of room for depth as we watch the parries and ripostes in the demon's character as it tries to grapple with the negative trait for good. Consider that, in Chinese mythos, yin and yang are only two forces, and yet their interplay is support to bring forth all the excitement and color of the world. > > Edit #3: Is it plausible for a community to be driven in unison by a > singular internal negative trait? > > > Yes. The model given was for an individual person, but you can make almost exactly the same model for that of a group, as long as they interact enough to form reciprocity relationships. A negative trait hitting that greater group could easily place itself in a position to "settle" into the individuals all in unison. > > For example, imagine if there is a village that is always angry, how > do they coexist with each other? If that's possible, could they > coexist with other villages that are always envious, greedy or > lustful? > > > How to coexist is an open ended question. However, if I may point to ideas, Bruce Banner is "always angry," and that is how he makes sure he can coexist. I'd also point out that many religions provide a path to trying to overcome vices, and they usually start by ensuring members of the religion can coexist. I'd point towards Buddhism, because it seems to be the most direct approach that works this way, but I would not discount any other religion's solution, because they all provide this support to their worshipers. [Answer] The key to humanizing villains is **a justifiable motivation**. Yes, they are doing lots of evil things, but they are doing them for a reason. 1. They need to do it to survive 2. They are doing it for the greater good For 1): Demons could have a biological need to kill mortals. When they don't drink the blood of a mortal every few weeks, they die themselves (blood of a virgin gets them going a few months). Torturing the victims to death makes them a lot more nutritious. Some demons might have moral qualms about killing, but they realize that they must do it to survive. By killing people in very gruesome ways, they actually save lives, because it means they need to kill fewer people. Demons with other shticks than violence might work similar. A succubus/incubus might need sex to survive. A trickster might get nutrition from people believing in lies. For 2): Demons might have some agenda which requires them to commit acts perceived as "evil" but which are actually for the greater good. Maybe they are darwinists who believe that by killing the weak they make the mortal civilization stronger in the long term thus serving it overall. Or they have clairvoyant powers and know that some innocent people must die to prevent much worse developments in the future. The demons killing sprees might seem arbitrary because their victims do not appear to be particularly good or bad people and do not appear to be obviously involved in something important. But they are always planned. The people they kill need to die because it's the only way to prevent bad stuff from happening, sometimes several generations in the future. But people without the ability to see the future can not understand that. [Answer] A good way to think about this is to consider where demons come from and I can see two ways that you can give them understandable personality traits that might help them become more interesting characters. **Demons are punished souls** People who have lived a particular way are judged either by the deities of a particular religion or attract the attention of some powerful malevolent being. They are seized ( perhaps in the afterlife, but not necessarily ) and changed, stretching and warping the characteristic that drew attention to them in the first place, their bodies are changed and their minds reshaped, but only in that single way- in all other respects they retain their humanity and may even try to mitigate the impact of their demonic impulses in other directions. This is part of their punishment - they know what they are doing is wrong, but they are unable to resist it. **Demons are possessors** In this situation a "demon" is actually a person possessed by a shard of demonic mind which attaches to them through a kind of magical parasitism and drives them towards depraved acts of whatever kind this type of demon is particularly attracted to. This actually creates some very interesting opportunities- consider the tabletop game [Better Angels](http://www.geeknative.com/39746/review-better-angels-a-supervillain-roleplaying-game/) for some examples - because the character is entirely human and yet subject to demonic whim. [Answer] Something that I discovered a while back was that things in this world that are good *are* good because there are other bad things to compare them to. For instance, there was an episode of the Twilight Zone in which a man gets to the afterlife and is told he can have anything he wants. He soon realizes that all his favorite games are no fun when he always wins, and people aren't nearly as interesting if they always agree. He complains that heaven really isn't all that enjoyable, at which point his guide informs him that he is not in heaven. The point here is that sometimes, bad things have to happen in order for good things to happen. You have to be hungry to eat a good meal, and you have to be tired to enjoy a nap. One could take this to the extreme and say that people need to be tortured, tormented, and even killed in order for the survivors to be happy. I've been wondering if we're getting close to the point where the Holocaust was worth it, given all the times people have decided against doing things because it made them look like Hitler (not to mention all the jokes people have made, but I don't feel comfortable trading human lives for laughs). This philosophy, that one must take the good with the bad, brings to mind the endless battle between angels and demons, the embodiments of the aforementioned good and evil. One might say that in the Garden of Eden (or whatever idyllic creation myth you prefer), humans could never be happy, because they were never sad. Furthermore, without being sad, they never had any desire to better themselves, and remained in ignorance. Thus, Satan and his demons decided to infect the earth with all the bad things they could come up with. As a result, early humans suffered, but in their suffering they began to think, and scheme, and invent, and devise new ways to alleviate their suffering. As humans developed, and evolved, and moved ever closer to the stars, the demons redoubled their efforts, and those who were able to triumph over them found even greater happiness. And with every new torment, humans became ever stronger, and more beautiful. This is your motivation to the demons. They want humans to be happy and live up to their infinite potential, but they know the only way that's possible is to make them sad, and hurt them, and try to hold them back. They also know that the angels will only ever 'help' the humans, which leads to shallow, useless hedonism. Strangely enough, a lot of 'sinful' behavior leads to some form of shallow pleasure, so demons may actually target these 'sinners'. While this may explain why your demons exist and why they act as they do, it leaves the door wide open for why they do it and how they feel about it. If a demon is the embodiment of anger and is always angry, they will definitely be thinking about that anger, and could have any number of secondary emotions about it (shame, fear, sadness, confusion, and more anger, to name a few). As to how other demons treat them, I'm sure they'll all have developed thick skins by living together. Thus, their interactions may seem brutal and vulgar to us, but to demons it'll just be business as usual. I imagine there will be a lot of introspection, as demons will have to face their fears and shortcomings every time they speak to one another. This also raises the question of choice: I've always thought it interesting that God can see the future, because if that's the case then he knows what he's going to do, and thus has no free will. If demons are the same, and can't really change the way they are or the job they have to do, that could be kinda sad (and a great reason to be jealous of humans, who, by most accounts, do have free will). On the other hand, if a demon chooses their life and work, I imagine a lot of demons would struggle with it; just look at war/action movies, where a soldier knows killing the enemy can save lives, but still wishes he didn't have to do it. Some demons may even switch sides, or quit their jobs in order to protect humans they've grown fond of. Of course, there may actually be 'bad' demons, who hurt people not because it's their job, but because they like to. There's a lot of options here. Bottom line, it's a tough job, but someone's got to do it. It may not look like it, but it's for the greater good (or is it???). That's something people can relate to, and I think it's a perfectly acceptable counter-argument to the good-evil binary. ]
[Question] [ Suppose wizards are are very common, like 1 in 3 people. Magic ability is inherent, but basically useless without special (fairly expensive) training. Obviously the military would not ignore them. I am picturing a military similar in structure to the modern US or ancient Rome, in a medieval setting. My question is, how would they be used strategically? I have thought of 3 main possibilities: 1. The military would mostly not go to the trouble or expense of training them, so there would be some specially trained wizards while most are untrained and integrated with the rest of the troops; 2. They **would** all be trained thoroughly, then integrated with the rest of the troops, so every unit has a few trained wizards; 3. They would all be trained, but put in separate homogenous units, or a separate branch altogether. Which of these makes the most sense strategically? Is there another option I have overlooked? [Answer] Having wizards and not training and using them is like having an armory full of muskets and not bothering to keep powder and shot. I think #1 is off the table that fast, if the military knows they have a large number They will be weaponized, just like people always do in D&D type games. No one packs theurgic spells, only thaumaturgy that will increase the local entropy quotient! Now, a great deal depends on what your wizardry is and can do. Maybe it's all informational type magic, but no fireballs and lightning bolts. You didn't tell us what "wizardry" is in your world. I will suggest that you grade ability, so you do not have one regiment of three that are fireball spitters, as this will seriously imbalance challenging characters and make your plot-building difficult. That is, even when trained, most people start out with lower abilities, or different abilities, and it's a rare talent that can play human flame-thrower. Of possibilities 2 & 3, it depends on how wizardry works. *Can* wizards be integrated in units, or is there something about mundanes that gets in their way? It's how you want to build it (me, I want weather wizards in my *navy*). A problem also comes up with "a military similar in structure to the modern US or ancient Rome" in that those are two fairly different things. But I do take away that you're talking about a soldier army, not a warrior/hero/knightly kind of thing, despite the "medieval setting" (classic herofy tech level & costume & culture, I assume, w/o feudalism). A Roman army (or Chinese armies in most eras) had separate units of slingers, archers, mounted javelineers, crossbowmen, clibinarii, and so on, kept separate from the infantry phalanx of the regular legionaires. A modern army has high integration: in the 20th C every unit has its radiomen, one BAR for every so many regular riflemen, a certain number of scouts, and so on. That could be your telepathic wizards and the one who does fire rain or static crackle (if you've ever gotten doubled up by a good static jolt, don't underestimate it as a weapon) while his buddies use their spears, and the wizards who can magically locate things or far-see are the scouts. Separation of units often had more to do with use (cavalry units do a whole different thing than infantry, and armored trench-attack units in WW1 only worked if they were a group that hit at once), sourcing (all your slingers come from Rhodes, and your archers from Crete, and firepower is better massed), or training and equipment (flame-throwers tended to be grouped, though one guy with the flame-thrower is supported by thirty regular guys, because flame-throwers needed all the same supplies to refill their tanks). I'm also going to suggest that if magic is a thing, you are more likely to have female auxiliaries in that line. Human "radios" are too damned valuable to waste good ones! They are not likely to be in the front-line units but back in the command units. They may also be in home-defense units, if no one wants little Miss Lightning Bolt in the frontal assault. She sure would keep down the number of siege ladders on her part of the city wall. Hope that helped! [Answer] Oh this is just royal. *One in three people* if magic was that common, the social impact would be immense, not to mention the military. But as you asked about integration into the military I will do my best to answer that. First, the military would be composed almost entirely of magicians, with mundane people only as strategists. (Note that even in medieval ages the ratio of soldiers to normal people was significantly less than one in three. ) As we have almost independent units that can lock together into a cohesive whole much of my military would be 2-3 "elder" mages to about double that number of "novice" mages who would graduate to their own units when they reached sufficient mastery. This means that instead of training people with swords and spears and such, training is entirely learning and mastering new spells. [Answer] One in three people is a lot of people with magical ability...I am going to estimate that as equal to the proportion of people in the real world who are "athletic". You could even use that as equivalent to the proportion of people in the real world who are "smart", or who at least demonstrate a level of intelligence that is at all noteworthy. So as a quality that a third of the people possess, just like athleticism or intelligence, not everyone who possesses the quality would have an equal share. Some wizards would be "ordinary"...compared to everyone who has any magic. Everyone would be tested in school for magical aptitude, their test scores on file, able to be accessed by any government agency. The CIA would probably keep track of the top .1% of wizards, and of course try to recruit as many as they possibly can, same as any other kind of talented person. Actually, with a full third of the population having any magical faculty whatsoever, you could extrapolate the patterns of how society would handle magic from how society handles any notable ability. Let's say, 70% are ordinary, 25% are notable (at least among family and friends), 4% are exceptional and work professionally, .9% are elite and hold extremely high positions in government/military/business positions, and the last .1%...are very hard for anyone to deal with. What they do in the military depends on how you define the scope of "magic". Obviously you have to have fire and lightning just because...but is telepathy involved? Clairvoyance? Really, clairvoyance would be a whole field of study right there. Here are a few possible dimensions to only clairvoyance: * Breadth: varying levels of precision depending on timewise distance from the present (5 minutes from now is more precise than 5 days. This doesn't have to be linear...perhaps some wizards are better farther in the future than close to the present.) * Spacial: varying levels of precision depending on spacewise distance from the current location of the wizard (1 mile away is more precise than 100 miles. Again, not necessarily linear...perhaps some wizards have a spacial locus that is a loved one, or maybe the distance is relative to the location of Jim Morrison's remains, who knows.) * Scale: varying levels of precision depending on the physical scale of the event (tiny events may be more clear than large-scale events. Some wizards might specialize in predicting the patterns of the world economy, others might be very good at knowing whether or not the mechanism in one gun is going to jam on the 23rd bullet in the magazine.) * Meaning: varying levels of precision depending on the living subject (The wizard can predict personal events with greater precision than events in someone else's life. Or maybe a wizard has their meaning locus attached to a loved one, or a pet, or maybe their future sight is not oriented toward living things at all.) That is just clairvoyance...and a third of the population has magic, you say...well, I would recommend a very strict definition of magic to make this all a bit easier. [Answer] An incompetent king can have the most powerful army in the world, but he will be stomped upon by any rising military genius. See this example: King Darius is a man of his time. He follows the current tactics of his time, without questioning their usefulness or the possiblity that they are outdated. King Alexander is a genius of his time. He innovates, by creating new tactics and refining old ones. Both Darius and Alexander train a number of highly trained wizards. Darius creates a single unit that behaves in battle like a group of archers. Alexander tests the strenghts and weakness of his wizards, and distributes them accordingly inside his army. He wins battles against progressively stronger enemies. Alexander wipes the floor with the armies of Darius. Alexander proceeds to wipe the floor with dozens of armies belonging to other kings. Alexander dies of old age, and his empire is broken by disputes between heirs. Everyone adopts the tactics of Alexander. The tactics are followed without innovations for hundreds of years. Hundreds of years later, a new military genius is born, let's call him Julius Caesar. He innovates the tactics, wipes the floor with other leaders, etc. Rinse and repeat. [Answer] **Economic growth tends to foster more economic growth** Economies are like feedback loops going into a microphone. (I'm not a real economist, so this analogy will be a little strained. Bear with me.) As an economy heats up, it feeds back into itself, making itself heat up more. The people who are doing well have more resources to spend, and that tends to bring others into the web of activity. (The reverse is also true: economic woe tends to sow more woe.) **The ROI on training a mage is immense** You haven't outlined what kind of powers the mages have, or whether they can develop new techniques via research, or how any of it works. But in general, the value that the average peasant's work will generate before they become a mage is so much less than the value they will be able to generate afterwards, that it will easily dwarf the cost of training all but the most useless of them. **Profligate mage training kingdoms will outperform stingy ones** The more mages you have, the more new mages they can train. The more mages there are, the more leeway you have to do far-off deep research, the kind that only pays off when, after decades of failure, you finally figure out how to (oh let's say) heal a previously-untreatable disease, cause an earthquake, or set up a telecommunications network. Paying for this training won't be as much of a problem as you may think. One of the natural side effects of having a huge supply of mages will be a huge stream of income as people hire them for all kinds of things. Consequently countries that have very liberal mage training policies will tend to be richer and more powerful than those that don't. **To actually answer the question** Unless the discovery of magic is recent, the world will have probably already progressed into an age of sufficiently-advanced magic to be indistinguishable from technology. Armies will be full of mages doing all kinds of magecraft, and the only use for a non-mage will be as support staff, perhaps bodyguards, and probably also spying. ]
[Question] [ Say you have a planet and the planet has a moon: could the moon have visible satellites as well? I don't mean a gas giant planet, I mean something habitable by humanoids or humans. Will the moon's satellite get pulled into orbiting the planet? If you are going to use detailed scientific terminology, please also try to provide a 'layman's terms' summary. My physics skills are rudimentary. [Answer] [Sattelites of the moon are unstable](https://science.nasa.gov/science-news/science-at-nasa/2006/30nov_highorbit): too close and it notices the lumpiness and does not make a nice ellipse, so after a while will crash. If too far, it will fall out and orbit the Earth instead. Look at the “[Hill Sphere](https://en.wikipedia.org/wiki/Hill_sphere)” represented as a topological map, and you get the feeling for how the gravity of the Earth interferes, leaving only a small region where orbits look like they would go around in a normal manner. But you can’t orbit that close, since the moon is not just [lumpy but off ballance](https://en.wikipedia.org/wiki/Gravitation_of_the_Moon). As it turns out, certain high-inclination orbits work out better, on paper anyway. So first, you need to find out what makes the hill sphere bigger. I don’t know off hand, but I suppose the moon can be larger and farther away. But if the moon is far from the primary, it has the same issue and will end up orbiting the sun, or easily peturbed from other bodies in the solar system. Also, our moon is rather lopsided. A more suitable situation would be to have the moon be especially symmetric. Perhaps it could be liquid? That would allow the sattelite to orbit close in and remain stable. Throw in some other reason to remain stable, like the all-powerful [*resonance*](http://onlinelibrary.wiley.com/doi/10.1029/2011SW000704/full). Make it slightly eccentric, make the sub-sattelite off-ballance and in an odd half multiple of its period, which is also a small multiple of the moon’s period, and furthermore have another large moon with a period an exact integral multiple of the moon’s. If that’s not quite right, it’s at least believable to the audience, if they don’t solve the math for real. [Answer] A few years ago I would have said stable lunar satellites weren't possible. High orbits near the [Hill Sphere](http://en.wikipedia.org/wiki/Hill_sphere) boundary get destabilized by the earth's influence. Low orbits are destabilized by lunar [mass concentration](http://en.wikipedia.org/wiki/Mass_concentration_%28astronomy%29)s (mascons for short.) Then I read the [Keck proposal](http://www.kiss.caltech.edu/study/asteroid/asteroid_final_report.pdf) for parking an asteroid in lunar orbit. I was surprised when they mentioned the possibility of parking the rock in a stable lunar orbit that would need no station keeping. Then I learned [Distant Retrograde Orbits](http://ccar.colorado.edu/asen5050/projects/projects_2013/Johnson_Kirstyn/finalorbit.html) (DROs) are stable even when approaching the boundaries of the Hill Sphere. One example of a body in a DRO is Jupiter's Moon S/2003 J2. This moon's semi-major axis is nearly 30 million kilometers. Jupiter's Hill Sphere has a radius of of 52 million kilometers. The [S/2003 J2](http://en.wikipedia.org/wiki/S/2003_J_2) Wikipedia article says > > The limits of Jupiter's gravitational influence are defined by its > Hill sphere, whose radius is 52 gigametres (0.35 AU). Retrograde moons > with axes up to 67% of the Hill radius are believed to be stable. > Consequently, it is possible that even more distant moons of Jupiter > may be discovered. > > > Our Moon's Hill Sphere has a radius of about 60,000 kilometers. In my orbital sims I have placed objects in a retrograde lunar orbit having semi-major axis 50,000 km. These orbits have lasted centuries. I would imagine a DRO at 40,000 kilometers could last eons. And this is high enough that lunar mascons wouldn't destabilize the orbit. In a science fiction setting, a moon with a larger Hill Sphere is plausible. DROs are long term stable in the outer regions of the Hill Sphere. [Answer] Yes, they can. However, generally satellites of moons will get pulled out of orbit. NASA has orbited spaceships and lunar modules around moons, proving that it can be done. However, the tidal forces of the planet will soon pull the moon's satellite out of orbit, probably into orbit around the planet. Maybe a large moon far away from its planet could support a satellite, since its own gravitational field would be stronger than the field of the planet at that distance. --- Source: <http://www.popsci.com/scitech/article/2008-04/could-moon-have-moons> [Answer] Let's assume this is the Earth-Moon system. If the Moon's moon is very small, you can easily have one. But the problem is it wouldn't be visible from Earth. If you want the Moon's satellite be visible from Earth with the naked eye, it has to be some decent fraction of the size of the Moon. But now you will have a 3-body system. This is not good. This is because the Moon's moon is large enough that its gravity can't be ignored. Usually, 3-body systems are unstable. So you would either have a collision or one of the bodies (probably the smallest will be flung out) The solution to your problem might be placing the smaller moon in one of [Lagrangian points](http://en.wikipedia.org/wiki/Lagrangian_point#L4_and_L5). Maybe L4. Having said that, it still may not work, as placing a large object in L4 might destabilize the system. Another solution maybe placing the smaller moon in close orbit around Earth. [Answer] moon is a satellite of earth, earth is a satellite from sun, so 2nd level satellites allready exist, but this is possible because sun/earth and earth/moon are very different and moon is not much perturbated by sun. [Answer] I just thought of something when I read the question again. Assuming that being physically small and low-mass compared to its primary makes an improvement, it could be *small* but still *visible* for reasons other than reflected sunlight on common rock. [Answer] If you can accept an unstable system, yes. From the perspective of a lifeform, the motion of the planets is unchanging, but in reality it is always shifting and eventually unstable. So you could permit a situation that was not stable given some plausible story about how it came to be - most systems are accretion-based, so the orbit has to be stable enough for the orbiting debris to accrete and become a moon. As an example, the currently accepted theory is that a smaller proto-Earth collided with a Mars-sized body, leaving a larger planet (the current Earth) and a vast debris field from the second body which has accreted into our Moon. The Moon is slowly moving away from Earth as the Earth's spin slows, so this is not permanently stable either. A possible story could be that a stable Planet+Moon pair meets an impactor flung out by a complex path around the giants in the system, which collides with the planet as above. If the original Moon was in an inclined orbit compared to the impactor's path, and suffered a glancing blow, there could be a period of time in which both moons orbited each other and the planet. Albeit this would not be long-lived, and would involve a lot of debris raining on the planet for a while. Fun products of this regarding stories would be: 1. A realisation of just how precarious the motion of the heavens is, perhaps explaining some environmental changes - even an early astronomer might be able to calculate some ongoing drift of their orbit and infer that they were due to collide 2. An icy second moon could be warmed by the tidal forces, permitting an ecosystem submerged beneath an icy crust to come to the surface 3. The Hill Sphere of a moon is very small, so for this to work for any length of time the two bodies would have to be rather close to each other 4. The oddness of the situation could be attributable to a meddling alien race either intentionally setting it all up or unintentionally creating the setup during other activities. An experiment to see if a race advances faster with a very clear example of the laws of gravities above them? ]
[Question] [ We are in a not too distant future. The current trends of computerizing and automating more and more decisions, including military decisions, of more and more surveillance (both state and private companies), networking of more and more systems, and big data have ultimately lead to the computer systems gaining all the power and the humans being essentially powerless and at the mercy of the machines, which turn out to work against the humans. However unlike the typical Science Fiction scenario, this is not because of the machines turning sentient and actively fighting the humans, but it's just that as the computers were given more and more decisions, were more and more connected, and their different algorithms started to interact in complex ways, humans were gradually put out of power, often without even noticing at first, and then the dominance of the machines, following blindly their algorithms all optimizing their own little programmed objectives without considering the big picture — because they were not programmed for that — has caused a hostile environment combined with Orwellian surveillance: There are cameras and microphones everywhere (and you better don't try to disable them, or a former police computer classifies you as troublemaker, and might send an automated killer drone to your place), and thanks to big data the computer network perfectly tracks wherever you are. OK, so much for the situation. Now a group of people intents to fight the computers. Since the computers are a mindless network, the way to do that is of course to hack into the system, try to disable key parts of the computer infrastructure, disable killer drones, manipulate cameras, all that. Which as soon as you've managed to get into the system can be reasonably be considered possible; they would use the powers they already have to gain control to more systems and do more manipulations until they ultimately succeed in either destroying the system, or at least reprogramming it to no longer working against humanity. However there's the problem of starting this. Thanks to the universal surveillance, and the fact that you inevitably will need time to hack into any system, the universal computer network would certainly detect any attempt at hacking quickly and counteract (quite possibly with deadly force). So my question: Is there any reasonable way how to successfully start the fight against the machines, without assuming some unrealistic weak spot (such as, for some strange reasons the machines don't do surveillance at a certain area)? [Answer] The way the question is asked, and the way the overwhelming physical resources of the orwellian systems is framed, it seems that the only true vulnerabilities will reside in * systems theory, and * information technology. This actually has some very interesting dramatic possibilities. @SerbanTanasa says "Never bring an ax to a Gamma laser fight", which is right and true, and I gave him a +1 on the strength of it. However, this isn't *really* a gamma laser fight either: it's an attempt to destabilize a complex system, via attack at *the only feasible attack surface:* the patterns of software code execution internally to nodes on the orwellian network, and message passing along the network itself. **This is kind of cool.** Complex systems are amazing things. They may be incredibly tough, able to take terrible damage... and shake it off, and gradually resume normal, or normal-ish, operation. On the other hand, a comparatively minor perturbation can propagate through the system, irretrievably destabilizing the system so that it shatters; or collapses into stable patterns that are not much like what they used to be. This is because **complex systems are composed of feedback loops.** Feedback loops are the fundamental analytical unit of systems theory, just as much as vectors are the fundamental analytical unit of physics. Your attackers would need to generate malware that would be designed to inflict the kind of critical damage that would shake the system apart. It isn't about physical damage, particularly; it's about disrupting the feedback loops. You can do this by destruction of key nodes that are routes for feedback; or you can do it by inducing oscillations in the feedback loops until they fly apart under the strain. Of course, your rebels would probably try everything. Their attacks would, in effect, *become* part of the system they are attacking. A fratricidal part. ...Damn, I hope you do write this. It could be a **lot** of fun to read. :-) [Answer] # We must dissent ## Cunning Humans Directed, flexible, goal-oriented sentient processes (like humans) generally prevail over blind optimization processes (like your oppressive computer software), with few exceptions. Since a world of 8 billion humans and trillions of smart devices is a hypercomplex environment, no amount of programming can specify optimizing behaviors to be undertaken in each world state, so a non-sentient intelligence like a computer will likely behave suboptimally in a vast number of these states, and catastrophically suboptimally under a subset of these conditions. No software is bug and backdoor free, and among the thousands of engineers responsible for designing and maintaining the robot overlords, there are bound to be a few who dissent from the program. Your best hope is to quietly identify these individuals, organize them using heavily encrypted digital or highly metaphorical physical communication methods. **Gradually, the set of vulnerabilities can be mapped, plans of approach created, vulnerable nodes subtly placed back under human control. Gradually, a committed group of humans can take over and disable the most pernicious parts of the system.** ## Feasibility of Physical resistance The amount of actual physical resistance possible will vary dramatically with the technology setting. Has the overmind literally sprinkled the earth with dust-grain sized listening stations, or is simply going out to a field or a forest and stripping off your clothes sufficient to render the machines deaf and blind? If the latter, organizing a physical resistance movement is simple, and can potentially be effective. If the former, dissent will be far more difficult. ## Never Bring an Ax to a Gamma Laser Fight Even if the level of surveillance is not complete, the firepower at the disposal of the overmind system might render it ineffective. If the battery energy density question is solved by that point, you might end up fighting against bots and drones armed with gamma ray lasers. As you probably know, very few substances can resist the application of megawatt energy over a small area for any significant time. Humans in particular have a tendency to explode fairly spectacularly. If such energy density levels are attainable by the overmind, heroics by individuals with Kalashnikov rifles will be brief and crispy affairs. Only by turning parts of the computer system against itself can humans have any hope of overcoming the overmind on the battlefield. More likely, while leaving the heavy fighting to the subverted drones and bots, humans will fight their own fratricidal war, attritioning the base of loyal maintenance and design engineers, turning political figures and waging propaganda campaigns to gain further support. [Answer] **Pass legislation** What do the Orwellian Machines use as their reference for marking people as *trouble makers* or criminals? If the machines just *enforce* the rules with cold, heartless, efficiency, then just *change the rules*. Bonus points if the legislation causes one half of the system to remove the other half. ;p [Answer] Since much of the Orwellian system will be devoted to pattern identification and matching, the human "revolutionaries" will need to be as random as possible. This is going to be difficult, since even looking at the sidebar of your Gmail page you can see the system can identify *you* by things like the keywords in your email, and your browsing history of Google. Big Data techniques take this up to 11, so trying to hide on the 'net is going to be difficult. Getting off the net as much as possible (sending messages on pieces of paper that are never scanned, faxed or otherwise on the net) and using random number generation to decide on which douse of action to use (at the most primitive level, rolling a set of dice or drawing a card from an unmarked deck). Enough of this could also start destabilizing the network, as pattern matching routines are disrupted with essentially null data (under a certain point the system might just be able to adapt), so somehow millions of revolutionaries will need to be working to undermine the system. [Answer] An interesting strategy might be to not attack the system directly. One of my CS professors was talking about viruses and security, and was saying that the worst kind of virus wouldn't delete data and mess stuff up. Instead it would just go in and change data at random to believable but wrong values. It would take longer to discover since nothing was actually broken, just wrong, and at least for a while any inconsistencies would be marked up to mistakes. A computer dictator would be even more susceptible to this, since a human looking at the numbers would be able to use logic based on experience. According to this data field, this person was born 150 years ago... that seems implausible... While a computer can't question it's data. That would be like someone slipping you lsd without you knowing about it. As you start to trip and the bugs are crawling down the walls toward you, but you can't run away because your legs fell off, you won't be able to figure out that you're drugged until it's all over and your brain is working again. [Answer] Depending on how smart the machines are, you might get away with actually [naming your son with a string of characters that breaks computer systems.](http://xkcd.com/327/) Also see [this](http://gizmodo.com/5498412/sql-injection-license-plate-hopes-to-foil-euro-traffic-cameras). Less dramatically, the mass surveillance probably turns all your speech to text at some point, and passes the text to a higher layer. It could be vulnerable to malicious inputs. So just strike up a conversation about classic computer attacks, and be very precise with the descriptions of malicious inputs. Try to affect something near you so that you know when you hit the jackpot. Good luck... [Answer] The old fashioned way. *Lots of axes*. The best way to *destroy* a system like this is to go after physical infrastructure. Cut cables, take down transmission towers, shoot down killer drones. Pick and area, cleanse it, and hold it. Move on to the next one. Hacking is.. a finesse thing. Humans are much better at actually breaking things. Another advantage here is 'traditional' military tactics, both in terms of regular and irregular forces work here. For taking down a 'red' machine controlled zone, guerilla tactics - paint on cameras, and generally blowing up installations would work well. Once that's done, go in, and hold those areas. Now, *historically* this has happened before on a small scale - the term [luddite](http://en.wikipedia.org/wiki/Luddite) comes from that and it was *ruthlessly* put down. Along with... *gross* vandalism (as opposed to petty vandalism), you'd probably need enough organisation for folks doing this to protect themselves. In essence, you'd want a guerilla force with enough training and intelligence to know what to hit, and when to hide. ]
[Question] [ Hear my Evil Overlord Plan: 1. Start personality cult and proclaim self as prophet of God or a divine being 2. Gather about 3000 followers of my religion (big enough to sustain population) 3. Develop ultra deadly virus which spreads really fast 4. Develop vaccine against such virus 5. Vaccinate self and all devotees against such virus 6. Release virus into the wild, effectively killing about 90 % of all humankind on Earth 7. Proclaim self as the divine healer and start getting devote followers from the common crowd by healing them (using the vaccine) 8. Start new religious culture Such culture would worship me and my family as the "holy ones," while the first followers of my personality cult would be "the clergy," keeping the literacy and knowledge about the technology. Because I am out of good names, they would be called "The Brotherhood of Steel." (There would be no one to claim copyright infringement, so I would be probably fine here) Now, the most important: Using the fact that all mankind would drop to "dark ages," I couldn't teach people to read and write, using the knowledge only among "the clergy." Meaning, only members of clergy would be allowed to learn how to read and write. I think I could refuse to teach literacy to almost everyone, because everyone would be too busy rebuilding society. So having no time for school could help me in raising the first generation to be illiterate. I don't really care about "normal" people dropping back to medieval state of mind, as long as they worship me and my family as the kings (or the Gods). The question is: How long would such setup be sustainable? How long could my offspring use the fact that I designed such setup? Will humankind eventually go back to the "post-modern era"? [Answer] It could be sustained for a long time. The Pharaohs went for millennia being worshiped as gods. If the people are kept ignorant, and the 'gods' perform periodic miracles (with the continued help of the 'clergy,') they can stay in power for a long time. The Mayans sacrificed other humans for almost 1000 years. L. Ron Hubbard, a rather mediocre to poor science fiction writer, announced that he should give up his day job and start a religion, because that is where the real money was. So in 1953, that is exactly what he did. Scientology was born, and a fleecing of the 'faithful' began in earnest. It's a legalized pyramid scheme (and tax exempt!) and people still flock to them, often even well educated. So done well, things could go very long indeed. If you can make them believe what you and they are doing is for the good of every body, you have it made in the shade. **EDIT:** I had another idea. "Save the children". When 'deciding' which 'heathens' to save, offer to save their children, bring them in, inoculate them and 'keep them safe' by brainwashing them into the cult. Leave the parents (who are dubious) to fate, give them a placebo for the cure or even infect them. Then, blame their death on lack of faith, etc. [Answer] ## Stamping out Literacy (as in 'eliminate' vs. 'reproduce rapidly in great quantity.', thanks UseNet) Stamping out literacy will require more than just not teaching 'em. Especially if you're not forcibly taking over the world, O Most Evil Overlord. You should start by torching every library, and every book. You should make a new language, so your holy books are in a special script. Of course, you've also created a huge problem in getting orders sent out, and getting information back to your hot little hands to/from your minions. Expect a lot of he said/she said, if you don't tech up and make everyone have tape-recorders for orders and reports. You also need to stamp out anyone who's not of your religion, who might want to teach their children how to read. Then you're going to have to go after the Fahrenheit 451 memory-book people. If you can manage all that, then you're going to have to put together some cultural memes: that writing is the work of the devil, corrupting God's language is a mortal sin, that clergy must only faithfully recreate the Holy Book and never use their writing script for anything else, that reporting a den of Satan-worshiping book lovers will win a person bonus points in heaven. EDIT: I've been mentioning how literate parents are a problem all over this thread, so I'm definitely in favor of bowlturner's suggestion for 'save the children'. Get 'em while they're young, and wipe out any of the older generation. [Answer] One of the key advantages of using a biological weapon is that it decimates a population while leaving it's wealth and infrastructure largely intact, but in your scenario this advantage may be a disadvantage. Take a look around. Writing is everywhere. On every product, building, street sign, etc. Forcing people to not be curious about the symbols that cover their world would be a full time job, requiring an awful lot of "evil over lording". Human nature being what it is, the more you try to suppress curiosity the more curious people will become. To give a little historical perspective on suppressing literacy: In the US before slavery was abolished many states passed laws making it illegal to teach slaves to read. Slaves who were caught learning to read were usually given 20-39 lashes. Those that were caught teaching them were fined and/or imprisoned. Now keep in mind this was at a time when the over all literacy rate was a bit lower, slaves were a minority population in most places, and that slaves were usually coming from non-literate cultures. Despite all of that, many slaves still learned to read. By contrast in your scenario: the people you're trying to enslave would be the majority of your population, they're coming from highly literate cultures, and from much more developed modern societies. Convincing them that reading is a right reserved for the clergy will be a lot more difficult. Perhaps [bowlturner's thought](https://worldbuilding.stackexchange.com/a/10790/7351) about only "saving the children" would be the most feasible way to accomplish your goal, but then your devotees would have to spend the first few years indoctrinating and babysitting **a few hundred million children**. 10% of the estimated world population of 6.916 billion would be 691.6 million. If you divide the children equally amongst your 3,000 followers you're looking at more than 230,000 kids per follower... That's a whole heap of kids to take care of. [Answer] Your tribe would be powerful but not productive. Small islands of naturally immune population will survive, in many separate "islands". If they are able to preserve literacy, and rebuild technology using preserved books, in few centuries they should be more technologically advanced that your illiterate tribe. [Answer] Without a conscious effort to promote literacy for the masses, it should be sustainable for centuries. Teaching everyone how to read and write is a very new concept in human history. Even though the first written languages were developed thousands of years ago, literacy was always a privilege of the upper class of society. The idea that everyone should be able to read is only a few hundred years old. In some parts of the world it has still not arrived. When you don't actively try to teach the lower class reading by building public schools and encourage people to visit them (for many households, a child is too valuable as a worker to have them waste their time in school), your subjects will stay illiterate. When you also culturally enforce that only members of a specific caste should be literate, it should be a pretty stable system. [Answer] Use a complicated writing system. Something pictoral probably. Alphabets etc are relativley easy to learn. Pictoral systems require learning every symbol, and if you don't know even a few symbols in a phrase, it stops making any sense. Sure, your clergy will have a hard time reading too. Mostly though, your situation is going to be the big thing here. With 3k people almost all are going to have to devote their time to food production. Especially as when your stockpiled tools and resources wear out, we're looking at being restricted to wooden and stone tools, no significant mechanisation. You might be king, but king of a rather poor tribe. Writing materials and time to read and write are going to be very hard to come by for everyone. ]
[Question] [ I want to build a world where society is composed of a few highly advanced individuals. Perhaps ruled by a council of elders as we frequently see, utopic society and all the usual tropes apply: 1. The members of this society are immortals 2. No one was murdered in the last 100000.... years 3. Highly advanced culture, but bored with the rest of the universe (seen all, done all) My question is: # If the individuals are so advanced and have nothing more to aspire to, what could motivate a power struggle? More considerations: If everything is allright and everybody, really, everybody is quite happy, what could be strong enough to break the status quo? Aside from the usual formulas: 1. Not everyone is really happy 2. Someone is bad to the bone but was hiding it all the time Only an external event could trigger a fight, or there are more individualistic views that I should consider? Please, fire at will.. every word inspires.. [Answer] Okay, so I'm immortal, part of small elite group of immortals, and we are all basically "good" - let's say it's unlikely to hide being evil for millennia. What could drive me to disrupt status quo? 1. Boredom: What if I've reached a level of boredom that prompts me to do something to cause a new reaction? This would be some kind of developed sociopathy. 2. Loss: Perhaps I've lost someone close to me through accident. No murders, yes, but perhaps through "normal" attrition, like a wreck. Now I can't handle the pain, or I want to change things so that the accident doesn't happen again, or I want to punish someone responsible. 3. Outside influence: We've been a static society for millennia. Now we've encountered humans. Humans flit through life, and make us realize that life is precious, meant to be finite if we want to appreciate it. The fear of death gives humans a drive and ambition that we have lost. Or maybe instead, they are encroaching on our way of life, and we need to beat them back or lose what we are - though that very action may mean losing who we are anyway. 4. Crisis: Superman's Krypton had a nice utopic society, but it prevented them seeing the truth of their eminent destruction, and those that argued for change were naysayed. That caused Zod to act outside of the norm. Finally, you might watch Star Trek The Next Generation, particularly the episodes involving Q. Q is "all powerful", bored, and outside of the norm of his populace. [Answer] Extrapolating from the real world... playing games. The possible challenge level of games scales with the ability of designers and opponents, and the time designers and opponents have had to develop their skills. The challenge level needed to keep players engaged scales with ability level of players, and the time they have had to develop their skills. If all the players and designers belong to the same "Elder race" and are equally immortal, experienced, and intelligent their is a natural match between challenge levels and the players will never get bored. As for the actual games, they are actually probably beyond our ability to even understand, but generally in fiction playing god, meddling with primitives, power games with your peers, and various scholarly and artistic pursuits have been used. But that is probably because they are easy to use in stories and remind people of the old gods. I'd recommend leaving the details of actual games vague and focusing in the consequences such as elation, disappointment, rivalries, alliances, and so on. --- DoubleDoubles answer mentions gambling. Gambling is addictive, which raises the point that while the Elder Race could no doubt resist and cure addictions, they would have no real reason to do so, if the alternative was boredom. As such they could have severe gambling or gaming addiction that would help them resist boredom. But from which they could recover almost instantly if required by circumstance. If they have no real reason to resist addiction the same goes for compulsive behaviour. H.P.Lovecraft had a Great Race that was rather compulsive about the study of history and the events and people of different time periods. Similar obsessions could keep an individual or even entire race busy for a long time. There is a simple cure to "having seen it all." You can simply forget some of what you have experienced. An Elder Race would have techniques that could put some parts of their memories in cold storage. They'd still have access to the memories, if they needed them, but in the mean time they could re-experience things for the first time as many times they wish. An ability to edit their own memories would also make them pretty good at infiltration. Infiltrating primitive societies could well be a favoured pursuit. [Answer] Ideology. Factions within them would have widely different and incompatible beliefs. For example one faction might believe that every other species should be advanced to their level (whether they like it or not) while another faction might believe in leaving people to advance on their own. You would need to come up with an irreconcilable conflict that is sufficiently grey that you can see people coming to different conclusions in which side to support and in which compromise would be difficult or impossible to achieve. [Answer] Are there any other peoples besides this race? perhaps they are trying to help raise other races. Maybe some favor one race over another and those 'child' races issues become their own problems? Perhaps they are just trying to understand the 'lower' races, they could very well have forgotten what it was like to be them. One interesting idea, maybe they envy the 'child' races for not being bored of the world. They could be trying to find a way to die, or less suicidally simply erase their memory, to bring back the spark and interest that life use to offer. It would be interesting to have the 'perfect' race envy the 'lesser' ones. Of course the idea that there is nothing to aspire to seems unrealistic. They can always fight to be the most important or most powerful of another of their race. They could be nurturing others (do they have CHILDREN to raise for instance?), they could still not know everything about the world after thousands of years, and be aspiring to find those last mysteries or memorable sights they haven't yet found. There is always love and friendship amongst themselves. They would have to be at a lethal level of depression to have no nothing their aspiring to. and as long as they aspire to something their have conflicts amongst themselves. I would warn you to be *very* careful with any race like this. It's rather unrealistic that any race could find harmony and happiness for everyone no matter how long they live. Look at how horrible humans can be to each other, look how even two good people can have personality conflicts that lead to them being angry and fighting. Trying to depict a world where *everyone* has found happiness is very hard to make believable to an audience, and risks them being seen as a [Mary Sue](http://tvtropes.org/pmwiki/pmwiki.php/Main/MarySue) race if your not careful. There is even [a trope about it](http://tvtropes.org/pmwiki/pmwiki.php/Main/CantArgueWithElves) I'm not saying this trope can't be done, but your going to have to show why they aren't perfect somehow. The short version is to have this race either out of the character focus/spotlight most of the time, or go out of your way to show issues, conflicts, and limits to their perfection, show why they aren't mary sues. a bit of [Screw You Elves](http://tvtropes.org/pmwiki/pmwiki.php/Main/ScrewYouElves) or showing how [Their lives really aren't that great](http://tvtropes.org/pmwiki/pmwiki.php/Main/CrapsaccharineWorld) would help. [Answer] One thing is always different and changing - *Individuals* Like-wise, anything complex involving something you could do with another individual is likely to be different depending on the individual you do it with. Even with the same person it would probably be different the next time you do it. --- ## Games The [answer by @VilleNiemi](https://worldbuilding.stackexchange.com/a/6749/2138) covers this topic pretty well. Even if games between themselves were boring for whatever reason, something like gambling could always put new species of the universe in strange circumstances to see what would happen. --- ## Relationships Even being immortal, exploring personal relationships with every other member of the species may very well be a never-ending task. Even if its not, exploring relationships with all the other species of the universe certainly is. *"Can't judge a person until you walk a mile in their shoes"* taken to the extreme, nobody has ever *been* another person. Given that they could somehow accomplish following or "living" another person's life, experiencing the life of every individual in the universe could also take an infinite amount of time. --- **TL;DR:** It is hard to "experience everything" when you really think about it. [Answer] ## Boredom Absolute power and absolute powerlessness are in their psychological effect indistinguishable. Power can only be measured comparatively, against a challenge. If there is no challenge, and each whim is instantly gratified, there is no struggle and no sense of achievment. Existential *ennui*, a form of absolute incurable boredom ensues. This engenders a sheer desperation that can result in **voluntary surrender of power** to one's lessers or even **extreme and reckless risktaking**, since "why not?" is a perfectly valid answer to such an entity. [Answer] Iain M. Banks 'Culture' novels and Stephen C. Wright's "Golden Age" trilogy deal with these issues. In the former case, most civilizations mass-suicide and 'Sublime' to see what the next state of existence is like. The 'Culture' keeps itself engaged by interfering with other, less developed peoples. In the Golden Age, humanity is still constrained to the solar system, but one man dreams of extra-solar exploration...and is spurned, for it is feared that a competing civilization would guarantee the return of war. [Answer] The search for something new would itself be a persuit that could never be completed. Imagine the main entertainment is exploring the possibility of something new, with different genres emerging such as physics, art, math, with different meanings of what "something" can be. The relationship between things is combinationally explosive and will exceed the capacity of a universe of things to comtemplate. Finding links between known things can be popular entertainment. [Answer] If the individuals are so advanced and have nothing more to aspire to, what could motivate a power struggle? Sad to say even for super advanced immortals the same things that motivate power struggles among lesser beings like ourselves. The control of resources, the competition between ideas & ideology, the frustration and complexity of social interaction, and the sheer perversity of human nature. You can add that fighting amongst themselves will give them something to do. Actually the universe is rich enough in its complexity and diversity there will always be something to keep people busy and engaged. The fallacy is that immortals will be bored witless about having nothing to do. Some pest will always come along and upset things. [Answer] Inventing and using a drug that for a short amount of time will erase their memories. They'd be using it for recreational purposes in order to feel things for the first time again. ]
[Question] [ Take, if you will, a sci-fi setting in which power is cheap and handheld energy weapons (blasters, lasers, plasma rifles, that sorta thing) are common. In this setting is an isolated community basically dedicated to stealth and assassination (think "ninjas in space"). Ostensibly, my space-ninjas favor traditional ninja weapons (shuriken, swords and the like) and ninja tricks over the energy weapons which are not only significantly more powerful but far easier to obtain, because of the stealth aspect: Any energy weapon which can generate and use enough power to be…well…an effective *weapon*, would basically be detectable by pretty much anyone with a mind to detect them. It would be like trying to sneak around with a giant neon sign flashing "← Here is a ninja". They may be many things, but space-ninjas are not stupid. If they could still do their job and sneak around while using a blaster, they'd totally do it. Right now, I'm sorta handwaving this away as being logistically impossible: sure, we could make you a blaster that can't be detected, but it would require so much shielding that it would either (a) lose all portability or (b) end up prohibitively expensive. And even then, it wouldn't help you when you decide to actually fire the thing. But I'm not sure how realistic this is. It seems to me that due to being portable yet practical hand weapons in the first place, heavy shielding would already be a built-in necessity just to prevent the device from arcing electricity everywhere or sticking to every metal surface around when it's turned on. However, my knowledge of electromagnetism is pretty much limited to high school physics class and having watched a lot of Star Trek, which isn't really as helpful as it might seem. I'm still researching exactly *how* the weapons would work, technology-wise, and since all worldbuilding to this point has focussed on the ninjas who plain don't (or shouldn't) use them it's not been a huge concern yet. I could easily just say that the plasma rifles are of necessity run off of a handwavium power cell — instantly detectable by any easily-produced handwavometer — and get the desired results (i.e. ninjas avoiding tech), but I would prefer to keep my handwavium within reasonable limits. For the purposes of this question, I'm less interested in the detectability of the hypothetical sci-fi power source and more about the detectability of any electrical device designed to draw and handle that much energy. Assuming everything is basically powered by electricity, how viable *would* it be to have — and use — that much power portably *without* it producing enough of a distinguishable effect to instantly set off an alarm from any system designed to look for it? [Answer] Uhm... I'd just like to mention some things from the humble perspective of a *physicist*. "energy" weapons would be among the stealthiest weapons **EVER** (if not **THE** stealthiest). Why? Well, first let's draw some parallels between our world and a world where "energy" weapons would even exist. I am assuming by "energy" weapons you are visialising fancy lasers and plasmas. If that is so - you are missing on cool stuff like sound and other sort of light. I will first overview the problems with having such weapons today and what would be the derivative of being ABLE to have such weapons at all. . # Lasers . Currently we, present generation people of Earth, are unable to use lasers for anything more than things like scientific studies and carefully planned surgery because of several limiting factors: 1. Power 2. Complexity and size 3. Lenses 4. Focus spot . ## Power The amount of power needed to make a laser that can literally burn whatever it is aimed at is not that great - a few small AA batteries should be able to do the trick - the laser in your DVD is actually powerful enough to do something like this, since as you might know DVD-writing devices actually use a laser to drill tiny holes in the disk. The problem is that when I say "literally burn" i mean just that - it would take seconds for a person to feel pain from that and if you want a laser that can kill people better than a gun - you'd need a LOT more power, which is not un-doable, but you either need powerlines next to you or a battery, bigger than yourself. ## Complexity and size Lasers that can do you any good are much more complex than your average hand-held laser-pointer, I should know - until recently I worked on a project about laser ablation. Lasers used in medicine and science are actually complex rigs, consisting of many moving parts, mirrors, lenses and etc. The size of the whole thing is at minimum half a human, and this is only half the reason you can forget carrying anything like it around - the other half is there rigs are stationery for a reason - moving them erratically would certainly break them. ## Lenses Lasers are THE most concentrated, monochromatic and straight ray of light you will ever see (or actually you won't but more on that later) lasers emit light only in the complete unerrorfulness and unfailingness of a straight line... until a certain distance. Like everything even lasers dissipate after a while, their range depends on your rig and lenses used, your focusing lens needs to be of high quality (which is no trouble, you can get high quality lenses for a good price even today) but its size also depends on your rig and the range you need the laser to be effective at, so like the size issue, today you would be unable to get a reasonably sized lens for a "killing" laser (mind you, let me mention there is sort of a lens/power relation -> to boost the power output of a laser, any laser, you can either use a better lens or more power. Yes, if you hook up your laser pointer to a power station the beam it would output in the first 0.0000000001 nanoseconds would be enough to kill an elephant... after which the laser would either melt or explode. On top of that the elephant won't die because this short time would be insufficient to transfer enough energy to its cells if the beam even stays focused, in layman terms.) ## Focus spot Lasers are lasers because they focus light onto a teeny-tiny spot, which is so teeny and tiny you would need to aim at vital organs to do ANY damage and even then it would rarely be lethal. Increase the focus spot, you say? Sure. You would just need several TIMES more power, like doubling the focus spot (and remember - your starting focus spot is about the size of a needle's tip) would require power^2, i hope you can work it out from there on. So in closing - all you need for lasers to be at least as effective as guns is: 1. Tiny batteries with a capacity of a hospital backup generator 2. Space tech lenses 3. Space tech mechanical parts and electronics . # Plasma . No, just... no. I would guess you are all imagining plasma weaponry as some gun-formed... gun that shoots reddish blobs of something and that something really hurts. I say that because movies, tv shows and etc. have always shown us "plasma" as something that does not look like plasma at all. Plasma is just ionized gas (layman terms), meaning you could imagine it as a puff of cigarette smoke and you would not be wrong. It's exact color depends on two things: 1. The color of the gas itself 2. The temperature of the plasma You can have plasma at room temperature, actually fluorescent lights use gas that gets jolted by electricity to become a sort of plasma. That particular plasma emits light in that particular way, because of the nature of the gas and what happens to it when it is exited by electricity. Other gases can be ionized without them lighting up like a christmas tree, some can be made into plasma and you would never notice the difference. But for plasma that you would like to hurt people - you'd need something else. Meet the [Argon Plasma Coagulator](http://www.google.bg/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCgQFjAA&url=http%3A%2F%2Fwww.asge.org%2FWorkArea%2FDownloadAsset.aspx%3Fid%3D3454&ei=P2N6VMH7NoaxaZTNAQ&usg=AFQjCNF69WM_VyBa322NH3Jp-IElOdiYEA) this is very much a real-world device used in medicine today. It basically consists of a power source, a probe and a grounding electrode. The basic idea is that the probe is cylinder-shaped and inside it are several cathodes. Gas flows through the cylinder and electricity is applied to the cathodes. The electricity then flows through the gas to the body of the patient and through it to the grounding electrode. By flowing through the gas the electricity ionizes it and creates plasma then either the electricity itself or the created plasma treats the patient, that depends on setting, intended treatment and manufacturer. The major problem with this device is that it requires a grounding electrode, this means that the electricity really flows *through* the patient to the electrode for the apparatus to function. That is why if the grounding electrode is not positioned properly the patient can suffer up to 3rd degree electrical burns. The reason I am mentioning this is because without a second electrode you don't get an electricity flow and you don't get any plasma, because as you may know if you point electricity to a point in the air and tell it "Go there!" it's gonna say "I don' want to. :( ". Basically to have plasma you need to have two electrodes - one at the starting point and one at the end point. How do we solve this problem? We don't. Some time ago I worked with a colleague on a "jet stream" plasma propagation version of the APC. The idea was to use a similar setup of a cylinder with electrodes with gas flowing through and with controlled electricity flow to create a sort of "plasma bullet" that would propagate on itself to the patient. The benefit of this setup is that it eliminates the need for a grounding electrode and thus the danger to the patient. There are articles on the jet stream propagation of plasma - i.e. the exact thing you probably want to do, the reason it is hard to do is because it is very much like trying to control the movement of a feather in a windy day just by blowing. Plasma bullets are really pig-headed and either don't get created at all or don't last long or don't go where you want them to. On top of that they are not nearly lethal enough, both because they are not that hot and because they cannot propagate more than a few centimeters, after that they just go "puff". To have a gun that can fire plasma that can kill people, even if you can supply the power, you'd have to come up with a way to ionize a puff of air and later making that puff of air travel in a straight line a long distance (good luck with breaking physics). But considering you can do all that, and if your world is space-age - why not, here are the reasons these weapons would be undetectable. ## Lasers emit NO SOUND. Nada. Zilch. Nichego. Zero. The only thing, relating to a laser, that can emit sound is either the target as it sizzles or the power supply. The power supply *could* emit sound if it has thousand upon thousands of volts going through coils in it - that is why transformers hum (not the Michal Bay kind, the real-world kind) but if your power source is humming the least of your problems is you would get discovered and killed, therefore if it is safe enough to be handled by people - it would be made in a way that would not make it be several thousand ampers of power waiting to burst. So no sound. No sound? But they can see it, right? Nope. Well, they can see the target melting, but you can never, ever, ever, ever, ever see lasers, unless one is directed at your eye, in which case - it would be one of the last things you ever see, even the modern day kind. The human eye only "sees" anything because light from somewhere has bounced off from said object into the eye. To see we need light to deflect from something, lasers shoot straight, there is no dispersion at their effective range, so you can only see the spot as the beam hits the target, that is why you only see a tiny spot from the laser pointers and no laser beam - forget all the movies you have seen. So to recap. Lasers - no sound, no light. Any real ninja would tell you that's the best weapon ever. I'll even throw in a bonus - you can't definitely say it was a laser that killed someone. What lasers do is actually 5 different effects, depending on power and exposition time, but let's just focus on the thermal effect, because you probably won't want to make people literally disperse because of photon wind. So lasers would burn people, the victim would be charred. Just like if you would use an open flame, a flamethrower, a molotov, etc. So while further investigation *could* determine it was a laser that killed the victim it can **NOT** be simplistically done at first sight. Also, there are no sensors for this sort of thing, unless you want there to be *magical* sensors, there is no way someone can tell you there was electromagnetic radiation here even a second ago, this thing does not leave any traces (besides the burns). It's like asking someone if they can tell, given all the equipment in the world, if someone has flashed a flashlight here yesterday. Plasma is pretty much the same, the only difference is that the plasma bullet, itself, would make noise due to the heat and friction and fluid turbulence effect and etc. but not a deafening blast, but more a buzz or hum. In closing, let me just say I absolutely deplore the lack of a "new line" formatting on this site. :) [Answer] # [Faraday Cages](http://en.wikipedia.org/wiki/Faraday_cage#Operation) Are Your Friends Faraday Cages are cages which block specific frequencies of light/electricity. They don't require any active concealment, because the concealment happens by virtue of the materials of the cage. In fact, your microwave has one, which is why you cook the food inside the microwave and not the person looking to see if the food is done. A similar setup would work for your energy-weapons. It's actually a low-tech solution, but it's taking advantage of physics to achieve your goals. People love doing that. # [Solenoids](http://en.wikipedia.org/wiki/Solenoid) Are Good, Too. Solenoids have the nifty property of making a very strong magnetic shield inside the loops but a very, very low magnetic field outside the loops. If you use these fields to direct, say, plasma, then this would be a good way of not only directing them but also concealing the weapon from any sensors. You should also note that solenoids make a practically uniform magnetic field inside its coils. This is good for accelerating things. People take advantage of this in locks and other linear actuators. # Other Considerations Your weapons can be considered stealthy for a few reasons. Range, size of the weapon, how loud the weapon is, and how detectable they are are all issues. Consider arming your ninjas with long range weapons, like a type of [sniper rifle](http://en.wikipedia.org/wiki/Sniper_rifle#Maximum_effective_range). They're stealthy because of their range and because snipers catch enemies at unexpected times. Perhaps you should consider your space-ninjas using simply [unusual weapons](http://en.wikipedia.org/wiki/Ninja#Weaponry), like the actual ninja. It is well-established by many sources that historical ninjas uses gardening tools as weapons, which most people would be (understandably) confused at seeing. ("You killed Bob with a plastic trowel! IT'S PLASTIC!") Above all, when choosing or designing weapons, you must bear in mind that you don't need the craziest or most effective weapon, you just need to kill. A rock to the head can kill someone just as dead as a stream of high energy plasma. [Answer] **There are probably alternative reasons for ninjas to not use blasters** First off, to answer your question about energy storage we'll need 2 parts. There is a lot of hand waving between present energy storage and science fiction blasters. Lets handle them separately. "Naked" energy, without sufficient containment, is an issue even today. We usually have to dress it up in chemicals or magnetic fields to keep it from getting in trouble. There is usually a tradeoff between energy density and how fast you can pull that energy out. The most "naked" energy sources are things like capacitors that are willing to let lose all of the energy in a flash (literally). More contained are supercapacitors, which are capable of storing much more per cm^3, but generally have more limits as to how fast that energy can be withdrawn. This makes them good stores of energy, but the energy has to be unspooled into normal capacitors before it's fast enough to work well in a blaster. More constrained than that are the chemical stores like batteries. They are even slower than supercapacitors, but currently have better storage density. They are also cheaper, and very safe (a supercapacitor discharging across your finger will still hurt!) **The military has an interesting solution which gives a very good balance of energy density and power: thermal batteries.** Some batteries, such as the molten salt batteries, take advantage of the fact that the reactions which deliver energy occur faster at high temperatures. In many missiles and similar one-shot devices, the batteries consist of a salt electrolyte which is melted by a thermal charge before the missile is fired. These can generate incredible power (energy per time), and have great storage density for their size! When you go into the science fiction realm, and start worrying about blasters, a little more hand waving is required. Obviously they have an energy source which is vastly superior in both power and energy density, and you suggested this means they must be shielded. You are correct, but there is a strong difference between "shielded so that it is safe to hold and operate" and "shielded so that ELINT teams cannot detect the eddies from the power source." The former only has to shield the hazardous classes of radiation, like ionizing radiation. The latter requires actively trying to disguise the signature of a weapon. Given how much money the military spends on SIGINT and ELINT, it is clear this is not an easy task... which means its not cheap. Most people won't care if anyone knows the blaster; they're wearing it on their hip anyway. **The mass market will only support development of safe-to-fire shields. ELINT shielding would have to be developed by special markets** However, there is another reason why your ninjas might choose to avoid the blaster. Consider Obi Wan's comment about the blaster, an inelegant weapon for a less civilized time. That sounds like Jedi prejudice, but you also note the pragmatic Sith hardly use blasters as well. It seems all those who learned the lightsaber tend to forgo the blaster when given the chance. When learning to be a ninja, you learn to turn your body into a weapon, fully under your control. As you approach this point, there are tradeoffs you have to make. It is simply not possible to be a master with the blaster and the lightsaber because you only have so many neurons in your mind. A ninja would learn a set of weapons which turn them into the ultimate stealth asassin. **If that suite of weapons is sufficiently effective, and the blaster training is too coarse to fit in with the rest of their skills, it actually becomes a hindrance to learn it!** [Answer] I'm going to split this into two parts, since the energy signature of the weapon while it's sitting quietly in your holster is going to be drastically different from the signature when you pull the trigger. ### Detecting a holstered weapon This might be a lot easier than you're expecting, depending on exactly how your weapons function internally. I can see two key areas where you might get energy leakage boosting the signature: the power source, and if the weapon needs to charge something before firing. Powering the weapon is the big question mark here. **If you're running off batteries and don't have to keep any internal force-fields/plasma reservoirs/whatever charged, then the electromagnetic signature should be pretty close to zero.** If you're not actually *using power* from a chemical battery, then it's not going to be giving off any electromagnetic radiation. There are still ways you could detect the battery itself (I'd suggest something like an MRI scanner), but they're likely to be short-range; good for a metal-detector type installation on a doorway, not so much for aerial surveillance. At the other end of the scale, **if you're running off a micro-fusion reactor you're going to light up every sensor from here to the North Pole.** A 'quiet' energy source like a chemical battery might also cause the same problem if you need to run internal electromagnetic containment fields for some other reason (storing plasma, perhaps...). Compressing that down to a portable size will take a huge, constant power drain - and huge, constant power drains are not at all stealth-friendly. **The middle ground between those two would be if the weapon needs to spool-up somehow in order to be ready to fire.** Perhaps it does use strong internal magnetic fields, but doesn't need to run them permanently - thirty seconds warning is enough to let you charge it up and get ready to fire. In that case, the 'powered-down' state would be stealthy but the 'charged' state wouldn't (and the 'charg*ing* state is potentially less stealthy again...) It's worth noting that any constant-signature weapon can be turned into a spool-up weapon *in theory*: all you need to do is design it so it can be turned on and off in the field. Whether that's possible *in practice* is entirely up to the world designer - maybe there aren't any man-portable batteries with enough juice to kickstart the internal generator once its shut down, or maybe cooling and reheating the internal plasma store can't be done in the field, or maybe it's just too risky carrying a weapon that takes a minute to get ready to fire. (Similar arguments can turn any spool-up weapon into a constantly-hot weapon, in turn.) Running through the standard sci-fi weapons (and ignoring the generator question for now), I'd expect lasers to have a low-level constant power drain (with the drain getting higher the faster it can recharge and fire a second shot); plasma-based blasters and particle beams to have a high signature due to plasma containment fields (although they could potentially be designed to spool-up rather than run hot constantly); and railguns/coilguns to be a high-signature spool-up weapon. ### Detecting a firing weapon This is where stealth is most likely to go out the window. **Anything using electromagnetic fields to fire is going to show up on sensors - that means all rail/coilguns and 95% of plamsa weapons.** There's essentially no way to shield this, either, since you'd need a completely enclosed shield... and that leaves nowhere for the shot to get out. A neutral-plasma weapon could potentially be a 'silent' energy weapon, but would be short-ranged and very hard to design. (It wouldn't need to include any electromagnetic fields, since the plasma has no electric charge... but that means you can't use electromagnetic fields to fire it either. And there are very few other effective methods for handling weapons-grade plasma.) A neutron-based particle beam would have similar advantages and disadvantages, but trades potentially better range for being even *harder* to build. **Lasers are potentially the most stealthy energy weapon to actually fire.** Virtually all of their electromagnetic discharge is contained in the beam - that's the defining feature of a laser - so detecting one directly would require you to be right in the line of fire. (At which point you don't need fancy sensors, because *you just got shot*) Atmospheric interactions and reflected light/heat from the target would still be potentially detectable, of course, but a well-designed laser will still likely be significantly more stealthy while firing than any other energy weapon. In summary, **you can make energy weapons as stealthy as you need them to be**. Most realistic energy weapons are probably going to be fairly easy to detect, but there are ways around that if you want to use them. Overall, the single stealthiest energy weapon available is probably a single-shot laser. [Answer] The most undetectable would be lasers operating outside the visible spectrum. The most common ones available today are infra-red and ultraviolet lasers. While lasers themselves are highly undetectable due to being highly directional, dust particles in the path can and do deflect some of the light and make the laser beam visible. One can imagine specialized smoke grenades being used to detect laser fire. Once you make them invisible however, detection via particulate matter in the air would be rendered useless. Note that while the human eye can't detect infra-red, some animals such as bees can. More importantly, any cheap digital camera/smart phone detects infra-red (try it yourself with your smart phone and TV remote). So IR laser can be detected. UV can also be detected by glow in the dark pigments. So one can imagine special smoke grenades that would make UV laser beam glow in the air. That leaves us with more exotic parts of the light spectrum. One of the more interesting ones is the x-ray laser. It was developed to knock out ICBM's. It's effective against hard targets like steel or concrete or bone but doesn't work against soft targets like cloth or jelly or flesh. Another interesting frequency to use that I can think of would be microwave which would be useless against hard targets such as metal but highly effective against targets containing a lot of water such as human flesh. [Answer] How exactly are you detecting energy weapons? It's less an issue of making the weapon undetectable and more about tricking the detector that there's nothing to see. And counter intuitively, the "smarter" the heuristics, the easier they are to fool. Compare `raise the alarm if energy density> 3kJ/sq.m.` vs. `raise the alarm if energy density> 3kJ/sq.m. IF there are no vehicles operating there, or IF no tools are recorded being used there or IF there are no more than 3 people there.` Register the use of power tools in the area and the system will ignore your energy weapon's discharge. ]
[Question] [ We have an outbreak of a zombie-like disease in major metropolitan areas. The disease itself has a slow incubation period, and after a time it becomes clear that it is spreading faster than they can handle, and it is time to try and close off the infected cities. There are two primary goals: * quarantine the people within the city, because any number of them may be infected * keep the "zombies" from getting out So the questions are: 1. How would you actually physically accomplish such a thing with a huge city? 2. How long would it take to get into place? * Bonus points if anyone could address issues specific to cities like New York, Chicago, and Pittsburgh. 3. Let's talk about politics and legality too... There's no way this could be accomplished without resistance. What are the legal issues?, who would be in charge (FEMA?) and how long would the debate delay action? 4. Could this actually work? [Answer] *I'll assume people panic and try to get out (otherwise this will probably work a **lot** more easily).* Probably the first action you'd have to take is reduce the effects of panic, which would cause people to attempt to flee en masse and cause all kinds of havoc, including problems related to quarantine. ## The Lie So you lie, but in a convenient way, so as to reduce people's certainty that fleeing is the optimal option. You broadcast that the outbreak has been identified, teams are working on a permanent cure and that people should attempt to return to their homes if they are within the city or stay at work or wherever they are if they live outside it. Claim that teams have already been dispatched to provide medical treatment, examinations for infection and temporary vaccination. You must *not* present this as an attack - it must look like this has been going on for a while and that people have already figured it out. > > *In the case of NYC, which is what I'll assume we're placing under quarantine, as an example, there is a so-called "syndromic > surveillance"[[13](http://www.nyc.gov/html/oem/html/hazards/events.shtml)] system they've implemented to monitor > disease outbreaks - this plan includes vaccine distribution centers as > well - thus, in the case of NYC, it's very easy to get people under > control until military lockdown.* > > > *Many thanks to KaguraRap for this info.* > > > Also, updates should also be broadcast, even if they're fake. This is to give the impression work is getting done and the plan is working and already under way. This of course won't influence everyone and it doesn't prevent accidents and problems overall - random zombie attacks will happen, people will go insane etc. but it will reduce the amount of people that will flee until you can lock the city down. The idea is to present the danger as smaller than it is - you confuse them enough to pause. All means should be used - police helicopters, radio, tv, everything. ## The lock-down You'd have to immediately dispatch police and military nearby to close off all roads leaving the city (obviously). While unlikely to happen, people might still attempt to leave using the sea, if the city has access to it, so you should dispatch coast guard to prevent this. You also make sure there's enough personnel wearing medical clothes or quarantine suits - chances are you'll need them anyway to make sure that those who are maintaining the lock-down aren't getting infected in the process. A few policemen and military units should scan the perimeter and prepare to set it on fire, if necessary. This is assuming that around the city, there's rural or suburban areas, so you're not going to burn people's homes. All these people should share the illusion that this is already taken care of and it's just a matter of time until it's resolved. The lie must keep being broadcast all the time - people might have missed it the first time and others might get convinced more easily when faced with the difficulty of leaving. They should be told that the lock-down is a precaution against infected people leaving and zombies escaping. ## Break-in Eventually you'll have to send troops in to separate people from zombies and clean up. They'd have to look calm and in-control as much as possible and should enter from prominent city entrances (large, main streets). This gives people somewhere to turn to and go to. As soon as possible, units should scour the city for survivors and zombies, sending anyone who isn't a zombie yet to testing, explaining the routine procedure and promising vaccination. People should be given placebo injections as part of testing and those who are infected should be taken to "monitoring" sections. Those not infected should be commandeered to keep things in order. *Keep people occupied and focused away from fleeing until it's too late.* ## Quarantine Once enough troops are in, people are divided enough and exits are blocked, you should have good enough quarantine that, if there's a huge second outbreak, you can just order everyone to stay put while you burn the city down. Start from the perimeter. --- Of course, the question is, do we have the time and people to make all of this happen? > > *For the following numbers and calculations, remember I am making huge arbitrary assumptions and have no idea about epidemiology, disease spread and related topics. Without knowledge of how fast people get infected, how long it takes to turn into a zombie, how long for symptoms to appear etc. there is no way to compute how many people are going to be zombies and how much time people had to figure out what was happening.* > > > First of all, how virulent is this disease? I'm going to assume `0.02%` have turned into zombies out of `50%` infected at the time actions are taken to contain the outbreak. Assuming this is New York City, that means we have about 20 thousand zombies, 5 million infected and about 5 million not infected (I'm assuming the City + people who are there for shopping, traveling, tourism, business and people passing through = 10 million). I'm assuming about `20e3 zombies` because that way, across the area of the City, which is `1,214 km^2`[[8](http://en.wikipedia.org/wiki/New_York_City)], we get about 16.5 zombies per square kilometer ( `16.44 z/km^2` ). This means, factoring in the population density which is `10,725.4/km^2`[[8](http://en.wikipedia.org/wiki/New_York_City)], we get a zombie to civilian ratio of `1.54e-3`, which means `1 zombie per 650 people` (this ratio, if we take [Dunbar's Number](http://en.wikipedia.org/wiki/Dunbar%27s_number) into account - which says we can maintain 100-150 relationships as humans - and [this article](http://www.nytimes.com/2013/02/19/science/the-average-american-knows-how-many-people.html), which seems kind of terrible but references a study that claims the average american knows about 600 people, indicates that by this point, about 1/3 of the population will have heard *something* and may suspect something is going horribly wrong). I'm using this amount because I assume, after having this many incidents of zombies, many of which will be taken to hospitals or attack people, over a period of a few days, it will be enough for alarms to go off (think of it as a disease - you're a doctor getting tons of incidents with the same horrible symptoms and the patients becoming murderously rabid after you think they're dead - it would look like ebola and rabies on steroids!). In other words, I'm assuming there is an attempt to quarantine the city after there are enough similar incidents around the city that pretty much everyone will have heard something and hospitals can consider it an epidemic or attack of some sort. The US has a density of `4.4 military personnel per 1000 capita` and a density of `248 police personnel per 100000 capita`. Converting the ratios so that we can add them, we get `2.48 police and 4.4 military per 1000 capita`, a total of `6.88 people per 1000` we can have contain the city. For New York, this would mean about 69 thousand people, but we can use the NYPD's actual numbers[[11](http://en.wikipedia.org/wiki/New_York_City_Police_Department)] which state that there's `34.5e3 uniformed` in service, which brings the total up to `78.5e3 uniformed` personnel. Add to this about `942 fire departments`[[4](http://en.wikipedia.org/wiki/Firefighting_in_the_United_States)] and about `34e3` firefighters, 2/3rds of which are volunteers. Thus we have a total of about `112.5e3 personnel` that can help lock down and quarantine the city. Going by [this article](http://theclea5rsky.blogspot.gr/2006/09/number-of-soldiers-for-successful.html) it seems we need `60-200 military troops per civilians` to occupy the city and lock it down. With our numbers, we have `127 soldiers and police per civilian`, so we should be good, considering these are infected people, disorganized and not likely to fight back. Going by the automobiles per capita for the US which is `800:1000` approximately[[12](http://en.wikipedia.org/wiki/List_of_countries_by_vehicles_per_capita), we can assume we have about `8 million cars` in the city. Assuming most people will want to take their families with them before fleeing and that some will have relatives and loved ones in hospitals or will be tending to them (or waiting for help), lets assume a third of the population gets in their cars and leaves. That gives us about `2.5 million cars` leaving. I expected the police to have, say, about 1 patrol vehicle per 16 police officers since precincts reuse vehicles (are they *all* called officers? I mean personnel), which would give us 155 police vehicles, which is not much, but going by actual NYPD numbers[[11](http://en.wikipedia.org/wiki/New_York_City_Police_Department)], it seems they have `8839` cars, `11` boats, `8` helicopters, `60` horses (lol) and `34` dogs, which is a *lot*. We have to assume the military brings in their own vehicles, including tanks, but I can't make an estimate on those (it would depend on what kind of corps have camps nearby, the speed of these vehicles on a highway, how many can be deployed from nearby etc.). Can these police cars form a blockade across all entrances? Lets see. Going by this map: ![Map of New York](https://www.lib.utexas.edu/maps/world_cities/new_york_city.jpg) we can see that the highways leaving NY are 95, 87, 1 and 278. I counted `12` entrances through highway, to the city, which is how most people will want to leave. That gives us almost `736` police vehicles per highway - too many. We can also count on the military again or call in the fire department to plant their 950-1900 fire engines across the highways, using hoses to prevent rioting. This way, we can have `950/12 = ~80` fire engines across the highways if we're fast and send all the police cars to block smaller exits and maintain some control until the military lock-down. > > *Police should also shut down and block all subways early, as KaguraRap reminds. See the comments for more.* > > > So far, assuming the threat is recognized in reasonable time, we should have enough people, vehicles and time to lock down the city. You can't really get a perfect containment within a few hours, but I think that there's going to be enough time and quarantine is possible. To get those that escape the city, you call all the surrounding police stations and tell them to keep watch of the road, block all cars from passing through, especially those coming from NYC. *oh also, I think I earned that zombie tag, so I **made** it :P* [Answer] **How would you actually physically accomplish such a thing with a huge city?** * Barbed and razor wire. Barbed wire would definitely tangle up zombies. Although the fact they can't feel pain means they could pull free with damage. If you setup enough layers the chance of getting through is reduced. * Concrete and Roads. The pre-made concrete such as blocks and sewage sections can be shipped and put into place relatively quickly. * Pits, Moats, and Flooding. Collapsing existing underground structures and dropping bombs to quickly dig ditches and redirect rivers. * Precision Demolition. You can collapse buildings to form barriers if you have enough tall towers. They aren't particularly effective but might be better than nothing. **How long would it take to get into place?** * If it's a water-bound area like Madagascar you would enforce naval barriers to prevent movement in and out. That can be interpreted as instantly. * Demolition based could also be done really quick * Wire and road re-use is next fastest as evidenced by trench building and the Berlin Wall. This is really only limited in speed by manpower. * Large concrete structures would take time to build and only become feasible when the volume of concrete needed is small. **What are the legal issues, who would be in charge, and how long would the debate delay action?** * Until the civilian ratio is low enough to stop outweighing the threat. This can be relatively high but I'm suspecting your looking at <50% civilians. * If the nation effected is nuclear then they have final say (probably the only say actually). And the military would take over. * For non-nuclear countries, at global scale everyone would be a piece in the game. Military and international organizations are the only ones capable of mobilizing the necessary resources so they would be the major players. You would of course see the Red Cross and other Disaster Relief organizations helping to save civilians. * As seen by our response to threats like cross-species transmission and the Black Death. We really don't respond the best to sudden threats (which is why we resort to martial law). Debate would probably last long enough to test if they could be saved which would require a capture team and some scientists. I'm thinking a week would be enough. * If they could be saved then you have massive legal and ethical issues which prevent anything other than quarantine from occurring. We would probably form an international organization similar to the UN if not directly operating under it. Expect it to be delayed for massive amounts of time as politicians and human rights groups debate. Months if not a couple years. You can definitely kiss the immediate uninfected areas goodbye. **Could this actually work?** Yes, but it's highly situational. As your total perimeter size increases (number of infected and size of them) it becomes less viable to quarantine in an enforced way, which is the only way you'd want to do. Zombie concentration and smaller areas lend more to air-strikes and will consequently lead to less quarantine activity. When its all blown over the infection sources may be post-disaster quarantined to prevent another outbreak. Even if its the least likely for a given scenario, as soon as someone discovers a way to save the victims (even if it only works for a little while) expect quarantine measures to show up. [Answer] > > could this actually work? > > > No. In all of history, no one has succeeded in quarantining a population larger than a few hundred. It's a fictional idea. Looks exciting in a movie, never work in real life, especially in the highly mobile world of today. The fundamental flaw is the idea of a mass quarantine is that infected people don't bunch up anymore in specific areas but show up sprinkled all over the country following major transportation routes and nodes. Owing to this mobility of the population ***the uninfected are effectively surrounded by the infected*** likely before the actual scope of the problem is recognized. It's like fighting an enemy whose is mobile when you are static. Your only choice is to turn hedgehog. Instead of mass quarantine, we would use a reverse quarantine. A reverse quarantine, also known as a triage quarantine, concentrates on protecting essential personnel and systems instead trying to isolate the infected. Its never been used on a large scale and where it has been used, they concentrated on protecting medical, technical and transport personnel needed to respond to the disease outbreak. In a zombie scenario, the strategy would be not to try to confine the infected and zombies to a small area because they would already be widely spread. Instead, the uninfected would create defensive pockets all over which could be quarantined from outside contact and protected from active attack. Such pockets could be anywhere even in individual buildings inside major cities. Inside the pockets they would ride out the plague. --- > > how would you actually physically accomplish such a thing with a huge > city? > > > The only possible means of quarantining a major city would be with area weapons and free fire kill zones. You wouldn't try to block transport routes but instead define an area of ten to twenty miles deep around the city. (That depth is necessary to prevent someone from walking across it entirely at night.) Anyone or anything detected moving in the area would be fired on instantly using aircraft and artillery with ground troops in MOP coming in only at the far edges as the final measure. Even then, you would likely have to resort to laying down chemical weapons over broad areas. Such a system could not be put in place without a lot of preparation because the troops would not carry out such horrific measures (they'd have to fire on children for example) unless they were all convinced it utterly necessary. Basically, everyone in society would have to understand the danger and recognize the solution months or years before the attempt to quarantine a city even took place. > > how long would it take to get into place? > > > Figure two weeks minimum to have enough personnel and equipment to seal off New York City. That's assuming they've planned and trained for the eventuality. If not, then anywhere form 30 days to never. In the US, the military is based in overwhelmingly in the Southwest. Only the National Guard is local. The Guard takes 72 hours for first deployment and then up to a week for secondary. Deploying the army from the Southwest would take up to two weeks. Remember, its not just the troops but the entire military infrastructure you have to move. The kill zones will require air power which will have to be shifted from the Southwest as well. Shifting air power means more than just flying planes around, it means moving the ground crews and all the equipment of an airfield as well. The military appears to move fast in many situations because they do threat analysis and planning years in advance. Then they train on deploying against this or that threat. If they have a plan in place they can move pretty fast but not Hollywood fast. (In the movie Cloverfield, the Army shows up within a couple of hours of the monster. Wouldn't happen.) If you know a lot of people in the military you will hear about canceled leaves, new assignments and unit movements that clearly get them ready to head for some trouble spot. All this usually happens before any political leader even muses about sending troops anywhere. For example, I know the US army was preparing for almost a month to possibly go to Africa before anyone publicly discussed it. This happens all the time and most of the time, they don't deploy, but they're always planning and preparing to do so in case they need to. From the outside, it looks like the military moves in a few days but behind the scenes, they've been in motion for couple of weeks. To my knowledge the US military has no serious plans for responding to a disease outbreak requiring quarantine and certainly nothing requiring massive lethal force. They certainly haven't trained for it. They would have to improvise and likely couldn't in time, largely because the task itself if nigh impossible. > > let's talk about politics and legality too... there's no way this > could be accomplished without resistance, what are the legal issues, > > > Legally, health authorities can still forcibly isolate infectious individuals as they did up through the 1950s but they will seldom do so today because of public outcry (see below.) At the start of an an outbreak there would be a lot of legal thrashing with authorities not using their powers. Later as thing deteriorated, martial law would shut down the debate. A state of emergency or martial law effectively suspends all law save military discipline. The executive powers, governors and the president are left to act largely arbitrarily as they see fit. The courts have repeatedly validated the executives traditional authority to act outside or without the law in emergencies. Historically, those in the executive have moved to address novel threats on their own authority and let the surviving lawyers rationalize it all later. That has happened a lot in foreign military and covert affairs but would apply to this scenario. > > who would be in charge (FEMA?) > > > FEMA would play a role, they do game for disease outbreaks and at least once the trainers sprung a zombie scenario on them just to keep them on their toes. But FEMA major focus is on providing communication infrastructure during disasters for local leaders and responders and organizing financial assistance afterwards. It's a small organization with less than 10,000 people, mostly bureaucrats. Disaster response in the US is actually the primary responsibility of state governments with most of the leg work done by the state National Guards. We're to big and diverse to handle it any other way. > > how long would the debate delay action? > > > Fatally. I can't see us responding to any such crisis with any alacrity. The moralizing over the ebola outbreak doesn't inspire confidence. I think far to many people see disasters and disease outbreaks as stages to flaunt their own imagined moral superiority instead of trying to save lives even if that hurts someone's feelings. For example, a lot of people hyperventilate on the supposed bigoted evil of precautionary quarantining of individuals coming from areas known to have active outbreaks even though such quarantines have over a century of proven effectiveness behind them. Basically anyone who tries to move aggressively to contain a disease by inconveniencing people who might not be infectious, faces automatic knee jerk opposition from a powerful political segment. Those who like to bully others by pretending to be more-compassionate-than-thou will block any harsh measures that might be necessary until it is to late. I saw that happen small scale in the early days of the AIDS epidemic back in the 80s. In one famous instance certain people freaked when medical personnel in San Francisco began wearing latex gloves whenever they dealt with patients. Standard procedure today, but back then it caused a lot of gnashing of teeth. There were protest, some minor violence and vandalism, and medical directors called before politicians to give accountings. That was just one of many episodes that delayed responses to the that horrific outbreak. A lot of people died needlessly because of those more interested in moralizing than saving lives. Now imagine trying to get those people to even consider possibly contemplating giving a warning that at sometime in the future the military might threaten to shoot someone carrying a zombie virus out of New York. We'll all have our brains eaten first. [Answer] There is one big question here. Do the people inside the city accept their fate and sit tight or do they try to escape? Unless they felt like they had a real chance to survive by staying the urge to flee would be overwhelming. You can expect massive crowds all fleeing the city by whatever means they can. Road blocks would be overwhelmed, people would be trekking cross-country and flooding out of the city using every means they can. In that situation it would be virtually impossible to quarantine the city. You have millions of people all desperate to get out. Even if you convinced troops to use deadly force and placed them in a ring around the city you would have to get them in position extremely fast and you would have a lot of trouble convincing them to fire on fleeing civilians. [Answer] Typically police and army will put up barricades at all roads in and out of the city plus a perimeter that evolves as the isolation lasts longer. Real life example of a perimeter can be the [wall of Berlin](http://en.wikipedia.org/wiki/Berlin_Wall). The roadblocks can be put in in a day (big roads first) the perimeter will take longer. Don't forget that you need supplies for the survivors like food and clothing. That will be brought in by the people controlling the perimeter through a checkpoint and rationed out. [Answer] This is just a short answer to address the latter part of your question. I highly doubt the authorities would be able to effectively contain it in the cities you mentioned. New York has the East River and the Hudson River; Chicago has Lake Michigan; Pittsburgh has the Allegheny and Monongahela Rivers, which become the Ohio River. It wouldn't be hard for a zombie or two to clamber into a dinghy from one of the docks and break the quarantine. The good thing about NYC being surrounded by rivers is that you *could* simply block off all the bridges to stop anyone from leaving Manhattan by land (and therefore by airports), but the other boroughs (okay, sans Staten Island) could not be quarantined like this. Add to that the airports around the cities (JFK, LaGuardia, Pittsburgh International, Arnold Palmer Regional, O'Hare, and Midway International, as well as Newark International right outside NYC) and you have a number of different ways for zombies to avoid land barricades. This is the additional stuff that makes the short answer a long answer. So what do you do? Block off the roads, certainly. Like I said above, that may not be much use, but it *will* help a little. Without going into a months-long multi-billion-dollar defense program, you don't have a lot of options for destroying zombies, but perhaps you could modify existing weapons and send in troops to destroy the zombies. And if you're really stuck and have given up to losing the entire city, my advice would just be to demolish it. The whole thing. If you're going to lose all the people inside, you might as well contain the problem by destroying it. Ahh, politics. Now we're in trouble. The outbreak will spread reasonably quickly. I would assume the government would have the legal right to go in and treat the zombies as hostile forces, but a) that would require a lot of effort and b) you'll have a lot of lawsuits if someone talks about how a soldier shot a grandmother (despite the fact that the grandmother was a zombie at the time). Shooting first and hiring lawyers later could solve the problem, but that will add a lot of legal battles to the whole mess. Shooting civilian zombies is a real grey area at the moment. And yes, FEMA would be up to their necks in stuff to do (and funding, hopefully). So I think the government would be able to have the president designate the zombies as hostile forces and then go in and destroy them. To heck with the lawsuits. The passive route involves letting the city go to heck, while the active route involves either destroying the zombies to let the people inside survive or destroying the whole city to let the rest of the world live. Not a lot of legal precedent for that. ]
[Question] [ So, since my dragons have a lot of limitations that are needed for flight, I thought it was to make them some strengths. Two that still remain are their intelligence and long life, which can result in them being extremely well-trained and with a lot of friends, but these advantages are worthless in the hands of a writer that is less intelligent than the character they're trying to depict. This brings us to elements that need to be thought out once, then can be used more easily. Yes, I'm talking martial arts. Now, dragons have six limbs (so, four legs and a pair of wings) and aren't particularly large, about the size of a large horse, but maybe half or even less their weight. They also don't have much muscle on their legs. 25% of their mass is their flight muscles, so their body is "on a tight budget", so to speak. They still have sharp claws, of course. The main strategy of increasing a dragon's survivability is by lowering their hitbox and armoring that. Most of their organs are (relatively) very small and efficient and are located close-together inside the chest cavity, surrounded by bone, flight muscle, and scales. Also, they have so-called "air blubbers" under their skin. Air blubbers are a type of aerogel, characterized by larger pore-size and being made out of a strong, fibrous material (which might have some carbon nanotubes in it). It resists tearing and is also flexible. I think it's a pretty neat idea for increasing their perceived size without increasing weight, plus it's additional protection against blunt attacks. With all that being said, here's my problem: **What kind of moves would dragons use, assuming they decide not to use their wings in close combat, and how would they work around their limitations in muscle mass?** Assume the standard opponent to be an adult male brown bear, claws can be used, the goal is to incapacitate the opponent by any means necessary. **VERY IMPORTaNT NOTE**: I guess I should've said it earlier, but a dragon's flapping amplitude is going to be lower than that of a bird: i.e: the wing will travel roughly the same distance as with birds, but the traveled angle will be less, making it appear as if the dragon is barely rowing with their wings, unlike a pigeon's clap-and-fling style of flight. This also means that the flight muscles won't be particularly long. **That small rowing motion will be very powerful, but the traveled distance won't be that great**. [Answer] Side note: "Martial arts" may be the wrong term here; maybe "fighting style." Martial arts are how humans try to make bodies that are built for armed tool using combat work in unarmed combat. Dragons are built for "unarmed" combat: claws, teeth, wings, tail... Perhaps we can draw inspiration from how other animals fight. Fighting styles **Dragons fight like swans** Swans attack by battering their opponent in the face with their wings to blind them, while pecking as hard as they can. This works because the wings of a bird tend to be long relative to the size of the animal and so have great reach, and as any martial artist will tell you, in striking, reach matters. Dragons would also use their wings to buffet and blind their opponent and make it easer to dodge counter attacks... but obviously they will be doing something worse then pecking **Dragons fight like horses** Horses fight by rearing back and swiping with their front hooves. This uses their big running muscles and can be enough to kill a man in 1 blow. Dragons would be similar but with the addition of claws. Horses also kick back with their rear hooves to lethal effect, as would dragons. **Dragons fight like snakes** Dragons have these long necks, and so good reach. If their reaction times are as good as birds or snakes, they would use their other limbs to attack and keep their opponent busy while watching for an opening to lunge forward with their head and bite some key part of the opponent, like the neck. **Dragons fight like peregrine [falcons](https://en.wikipedia.org/wiki/Peregrine_falcon)** Peregrine Falcons hunt by diving down on their prey and either grabbing them or stunning them by striking them while in a high-speed dive. It would be normal for the Dragon to be at least beginning a fight with a dive from a considerable height to strike its enemy at high speed with its whole weight, probably with its front paws. **Finally dragons run like horses and birds** So this dragon is the size of a horse and it can fly.... I know bears are faster then humans, but I doubt they can keep pace with the flying horse dragon on the ground or in the air, so if the dragon feels it is outmatched, it would just turn tail and take off. [Answer] I don't really know martial arts, but since sheer power isn't an option, dragon martial arts would therefore be about *precision.* Stab someone in the right spot, and they're dead. Strength has very little to do with it. Sure, air blubbers resist tearing, and I'm sure these dragons have tough scaly hide, but if that were the case, these dragons would likely have evolved sharper and sharper claws and fangs. See, if these dragons fought each other a lot over the course of their evolution, the ones who couldn't slice into their opponent would have died. Martial arts would also be about *strategy;* if you hit the sciatic nerve on the human being, brightside.me tells us "This nerve is located between the groin and the knee on the midline of the inner thigh. A severe knee hit will cause intense pain, shock, dizziness and temporary immobility of the foot." Hit a dragon's pressure points, especially those *on the wing*, and I'm sure you'll have just as much a dramatic effect. Instead of powerful punches or wing strikes, I believe these dragons will use quick, accurate attacks to kill or debilitate opponents. [Answer] I'm no expert in martial arts, but I think you're starting with a faulty assumption about how your dragons would fight. 25% of the dragon's mass is in the muscles driving the wings, you stated: for a flying creature, that's a reasonable or even necessary figure. Some quick Googling tells me that arms make up about 5-6% of a human's body mass, and obviously not all of that is muscle tissue; I can't immediately find figures for how much of the muscles in the chest support the arms, but it's certainly a lot less than 25% of total body mass. It doesn't stop people from throwing some nasty punches. Despite your assumption that dragons won't use their wings, **those are their main weapons**. Even in a human, that great a percentage of muscle devoted to the arms would see everyone throwing rib-breaking blows with little effort. Scale that up to something with (according to your question) around a third to a half the mass of a large horse (so anywhere from 300kg to 450kg), and those wings will strike hard enough to break bones. It takes a lot of strength to flap giant wings with enough force to fly, because they basically have to be able to push that air down hard enough to counter gravity (incidentally, I think that chin-ups would be a trivial exercise for them in theory). What does this mean, applied to combat? The wings might be vulnerable, easily torn in the face of claws or sharp blades: this is probable, even, since making them thick or durable enough to resist such attacks will cost a fair chunk in terms of weight, and flying creatures are extremely weight-conscious. However, one flap of those wings is going to strike as hard if not harder than that brown bear they're fighting. Aim for the side of the neck, and it could well break; go for the windpipe, and you can absolutely crush that. You can go low: with the size of the wings, you can sweep the bear's legs out from under it and leave it easy prey for another strike. Properly timed, you could spoil the bear's balance just by slapping its leg or head as it goes for you and send the bear stumbling with that force; a quick pounce, and you have its neck in your jaws (or simply bash it senseless with further wing-strikes). The wings also offer a range advantage: they're going to be several metres long, far more than any bear will have. For bonus points, flapping the wings at the ground will kick up a nasty storm of dirt (or dust, snow, whatever is there), blinding the opponent and generally spoiling their own attack. Note that all of those were minimalist options, with the bare wings alone and any other limbs ignored: they didn't even require the dragon to have usable claws, much less tools. If you have claws, that obviously gives you still more options. Hooking the opponent's flesh to drag them off balance, targeting weak points like the eyes or especially the neck (slashing the main artery there would be easier than snapping the bone), and generally causing more pain and injury and blood loss; those would all be relevant options, and there's likely other tricks I haven't thought of yet. I'm not sure the dragons would even need tools to fight that bear reliably, but those could obviously make it still easier. They might have trouble handling long weapons (a pike being held by a multi-metre-long wing will likely have accuracy concerns, unless the opponent is dumb enough to charge head-on into it), but it doesn't take much to create a deadly threat, not when their wings are already far longer than any sword. Six inches of spear point at each wingtip would be more than enough to pierce the opponent's brain, and the huge wings offer them the range to easily make the first (and likely the last) strike. I'm assuming here that the dragon is for whatever reason confined to the ground during a fight (perhaps lifting from the ground requires preparation and leaves them wide open), confining the action to a mostly two-dimensional plane. If you add aerial strikes, the smart move for the dragon would be to simply ambush from above with a spear or lance of some sort. This would have to be held by the weaker legs, but the speed of a dive would provide all the force required to skewer that bear rather spectacularly; that blow would have several times more force than any cavalry lancer's charge. **Conclusion**: Your dragons are going to be fighting mostly with their wings, and they're going to be striking with the might of hammers. Expect them to focus on maintaining the proper distance, because they're extremely vulnerable if someone gets inside the effective reach of the wings. I'd advise looking into naginata fighting techniques if you want more details, or perhaps halberds. [Answer] assuming this is mean for unarmed combat(its another story if you mean armed combat), as other has say, they have sharp claws and teeth, but i also want to include grappling just like in this komodo **dragon** do for example. [![enter image description here](https://i.stack.imgur.com/ApMML.jpg)](https://i.stack.imgur.com/ApMML.jpg) or you can grab them and carry them high enough and drop /slam them down, can also include spinning to make them dizzy like in pokemon movement/technique by charizard. especially if against non flying opponent that can be carried or lifted. outside of that is swiping movements or slap using the tail, even better if the tip has spikes or like ankylosaurus tail, and if want to include the wings you can use the flying kick (can be change with tail whip if the leg is not long enough). [![enter image description here](https://i.stack.imgur.com/M4DR0.jpg)](https://i.stack.imgur.com/M4DR0.jpg) also assuming their teeth is more like crocodile or alligator they can use it to bite and spin to shred the opponent body, or become part of the grappling technique to pull or bin them (i assume their jaw muscle is strong) like how crocodile do (need to be careful, since your head or snout or neck is pretty much vulnerable or exposed in the front or if done in wrong timing it can end up bad, but thats pretty much how unarmed fight is, theres always risk or inevitable exchange blows, also depend on how your dragon neck or head design is, if it already upfront like most lizard then theres not much problem, different story if their neck position is like horse or swan image up there, that is more positioned upward, then the dragon need to be careful, like i already mention). if they has horn they can shake their head to deliver a puncture or simply charging to pierce the opponent, but it also vulnerable to get grasped or hooked (but that depend on the horn shape and length). and the old shooting fire in your face, or as distraction or blurred opponent vision or attentions, if your dragon is immune to fire and your opponent is not, they can just lit themselves to make sure opponent cant grasp or try to not come near, while you still can grasp them to wrestle/grapple or slam/pin/lock them down to get the burn (not recommended against hedgehog, especially the one that can teleport behind you). [Answer] ## Armed to the Teeth: Seriously? These things have claws, many are shown with a wing claw, they have fangs, and let's not forget the classical barbed tail (possibly poisonous). A completely untrained dragon could overwhelm a ninja master through sheer VOLUME of attacks. A lot of what I am presenting here is based on an article in [Dragon Magazine #134](https://annarchive.com/files/Drmg134.pdf) or from the articles references therein (especially [#50](https://annarchive.com/files/Drmg050.pdf)) You mention that 25% of mass is wing muscles. Even though you don't want them to use wings as weapons, they will be extremely lethal ones. Do the dragons have plain wings, a wing claw, or maybe even a small hand on the wing? If the goal is to keep the wing away from harm, why not let the dragon carry/mount a whip or chain on those bad boys? They'll have reach, stay out of trouble range, and still get to flail around in a suitably distracting/terrifying way. If you like, even a weighted rope could be used to entangle opponents , keeping them still for many other lethal attacks. While the wings don't need to be used as weapons, they will allow dragons in an open environment to lift off briefly and optimize the use of four claws and the tail. Additionally, wind buffets can knock people over OR propel thrown sand at high speed to distract and blind (I'd advise nictitating membranes if you go with this strategy). Many martial arts have a multitude of weapons associated with them. Yes, because of the claws, the dragons don't really NEED weapons - grab an opponent, dig in, and hold them still while you go in for a decapitating/skull crushing bite. But if you want to extend the reach of the dragon and keep the more vulnerable parts away from opponents, why not some really long, thin swords? Long pole-arms like a naginata could even be swung to strike opponents while flying out of reach - imagine a fly-over decapitating sweep. Drop a net on opponents ( a natural weapon for a flying species) to pin them in place, then sweep in with a barrage of deep stabbing weapons. More importantly, nets were often used to entangle the weapons of opponents defensively. While a human who throws a net is occupying critical hands, the dragon has an array of additional limbs at their disposal. And an enemy pinned on the ground is easy prey to a clawed foot-stomp. Finally, let's not forget the tail. It's likely to be long and sinuous to counter the weight of a long head. There's nothing that says it can't have a poison sting, or an infectious barb, or just work like a whip. Who's to say it can't be wrapped around another weapon like a sword, knife, or flail? A prehensile tail can sneakily wrap around an ankle and jerk, or leverage the size and weight of the dragon and simply sweep the legs. [Answer] > > "A spot. Where it's voonerable. My grandad used to tell me stories. Hit a dragon in its voonerables, he said, and you've killed it." - **Guards Guards, Terry Pratchett** > > > Dragon martial arts are for fighting other dragons. A dragon against a bear is closer to hunting. The dragon is going to strike from above and behind, any time the bear puts its head down. Fundamentally a dragon as you describe is not going to go head to head with a bear, the bear is heavier, stronger and likely more resistant to damage, it's dangerous prey. If the bear hides in the woods to protect itself from aerial attack, the dragon should let it go and accept the hunt has failed. (Dragon martial arts, where dragons are fighting other dragons is going to be a far more complex prospect, but technically outside the bounds of the question.) [Answer] **Flip them Over.** It is well known that ants bounce but elephants go splat. When fighting large animals Judo is more effective than Karate. When fighting a bear you should, rather than batter it to death, try and flip it over so it falls and gets injured. True, you don't want to use the delicate wing surfaces to fight. But you do want to use the massive muscles at the front of the body. [Picture taken from D&D Beyond.](https://www.dndbeyond.com/monsters/adult-blue-dragon) [![enter image description here](https://i.stack.imgur.com/9FQj3.jpg)](https://i.stack.imgur.com/9FQj3.jpg) The strategy is to crouch down low, dive under the bear, and then spring up and extend the flight muscles. If this goes as planned the bear rises onto its hind legs and then falls over backwards. If it fails you keep going, leap six feet into the air and spread your wings in a display that makes you appear much bigger than you are, and hopefully scares the bear off. Note this works better if the wing joint is backwards compared to the picture: [![enter image description here](https://i.stack.imgur.com/fhMIQ.jpg)](https://i.stack.imgur.com/fhMIQ.jpg) The first dragon has to push with its *wrists*. The second can push with its stronger elbows. **Edit:** This martial style developed from dragons fighting each other for mates. In that context the goal is to overpower your opponent without injuring them permanently. This works for dragons since they can recover from being launched by opening their wings to prevent falling over backwards. Fighting on the ground is also (a) less energy intensive and (b) can be done while guarding your mate, unlike fighting in the air which involves loads of swooping around. ]
[Question] [ A popular trope with some basis in history is the "travelling merchant", who visits remote villages carrying merchandise both common and rare, and many stories from strange lands. I've got a scenario in my mind, which is the expanded, aquatic equivalent of this. You have a family who operates their own trading company. But their company floats. For generations, they have sailed from port to port, picking things up in one place and selling them at a profit somewhere else. They do not follow a fixed route, yet their business is successful, and while they started with a single vessel, over time they could purchase more smaller ships - so as not to put their eggs in one basket and risk their fortune sinking all at once. The main character of the story grew up in the fleet. So I'm thinking of three to five vessels, all relatively small, but together capable of crossing oceans. There's a total crew of a couple hundred, and put together they speak every language on the planet. The story is not set on Earth, but the geography, politics and available technology is vaguely similar to the 1400s Indian Ocean. So you have strong empires, backwards tribes, thriving commerce, and active pirates. The thing is, most trading expeditions in history were sent by nations, or later by trading companies powerful enough to act like nations. I don't think my nomadic trading fleet concept has a parallel in real history. I think I can justify them not having a shore-based office as a cultural thing; like the Romani, this family has a nomadic lifestyle, and they just happened to have become wealthy doing it. It's possible they are treated as undesirables by the nations, and are not even allowed to settle anywhere. But, the question: is this concept economically viable? Could you have a small fleet that goes from port to port, making a profit selling stuff they picked up in foreign lands, and competing with trading companies that have a fixed route and shore offices, not to mention the support of nations? And if not, what can I change about the economic circumstances of either this fleet or the economy, geography or politics of the world at large, in order to make the concept viable? **Update**: I am tweaking their business model a bit. [Tramp trade](https://en.wikipedia.org/wiki/Tramp_trade) was a 19th-century thing similar in concept (cargo ships without a fixed route), but these ships were routinely chartered to carry something to a specific place. Because this is meant to have a more independent aesthetic than that, I am going to make it so that at a given moment, about two-thirds of their cargo has a specific destination, for which they were hired by a larger company or a small country. They do not take a direct route there however, and the remaining third is goods they buy and sell based on their own insights. I think this should make them more economically viable, whilst at least partially preserving the ideal of an independent fleet roaming where the winds and profits take them. [Answer] ## A ship is a horrible place to raise a family *To be clear, I am not saying the mixed-gender crews do not work, nor am I saying that it is impossible to design a ship in such a way to account for family life, just that historical ships lacked the space and privacy necessary for a properly functioning family unit.* The #1 reason you don't see nomadic sailors is because ships are way too confined places for families to live together for long periods of time. Men and women get along great for a few hours a day, but in general men are wired to need long periods of quiet focus which you can not get on a ship when confined with a large number of women and children. The male psyche is designed to 'abandon' his family so that he can provide for his family. Almost every sailing culture in history has had strong taboos about women being on board because of the variety of psychological problems this could cause in such close spaces. Nomadic caravans worked out much better because the men could scout ahead, hunt, forage, or simply walk apart from the family because he is "ummm... in the forward guard, yeah that sounds like a good excuse." This is why even the most maritime focused of cultures still maintained home ports to go back to, because they needed a place to raise their families which was not where they worked. But even without an exact historical example, we can make some inferences about how this could work. ## Vikings traded on unestablished routes In the medieval period, ~90% of wealth was kept in tradeable/usable goods rather than currency. This means when vikings would sack a town, they would be taking tons of trade goods that they often did not have a direct need for. They also did not have the manpower to attack many of the towns they would find while exploring; so, when they came across larger towns or cities, they would often stop to unload their pillaged commodities for things that either had a more direct need for or silver coinage. This meant that they were trading along unestablished routes because what they were really looking for were small poorly defended communities that you often had to go off the beaten path to find. They did not need to make the same profit margins on their trade goods as regular merchants because their commodities were generally "purchased at extremely discounted rates"; so, sub-optimal trading was okay. ## How your scenario could have evolved Vikings needed hometowns, but as history progressed, northern European towns got better and better at defending themselves. Historically what this meant was that vikings kept having to go farther and farther out to find easy targets, or they had to take bigger and bigger risks attacking better defended towns. This issue was actually what ended the viking age as viking simply became to big of an investment in time or risk to still be sustainable. For a viking clan to remain viable past the 11th century, they would have to abandon the idea of having a home to go back to. Unlike most other European civilizations, viking women often had many of the same freedoms, privileges and responsibilities as men. They were trained to farm and fight and perform more masculine trades so that the village would still function while the men where away. This means that training women to also be sailors would not be a huge stretch for their social norms (as long as they are not sailing with the men). This is where your ship convoy comes in. Convoys are typically combinations of larger less maneuverable merchant ships surrounded by smaller more maneuverable military escorts to protect them. By placing women and children aboard the larger "village ships" and allowing them to be fully manned and captained by their female crew, the men could meet their psychological needs by going out onto the smaller escorts while the families are kept safely in the middle. This gives your a situation more similar to a caravan where people can come together and segregate as needed. Now your fleet can explore (and raid) the whole world without ever having to turn back home. As time goes on, this fleet would develop a far more comprehensive map of possible trade routes than any merchant company would have access to such that they could eventually stop raiding and just trade. Instead of connecting 2-3 major port cities and letting the cities make the man-in-the-middle profit of distributing these goods, they might interconnect dozens or even hundreds of smaller towns directly by knowing precisely what each town needs and when. At times the the fleet might park in a hidden alcove in a river delta while a dozen smaller escorts sail off in different directions with precise amounts of goods, to all of the little towns within 1-2 days. At other times the whole fleet might sail up to a major city with goods from a 100 different farmers, miners, and craftsmen around the world each purchased at the lowest price possible. These trade routes would be so complex and inconsistent as to seem randomly nomadic, but to the enigmatic fleet elders it is a complex formula of precisely timed stops based on a deep knowledge of places that other merchants have just never gone far enough out of their way to know about. ## Surviving against militarized trade competition As L.Dutch points out in his answer, large trading companies in the late medieval and colonial periods turned to military force to protect their economic interests, but a post-Viking fleet like this is the last thing you want to compete with on that level. The fleet is not so large or spread out as to put the major trading lanes out of business, and the cost of fighting them makes about as much sense as the Seleucid Empire attacking Sparta. Win or lose, you are guaranteed to pay a bigger price fighting such a fleet than any profit margin you might hope to gain. ## Surviving against storms Storms are a constant danger on the deep seas when you are travelling direct routes between major ports, but this fleet would by its very nature stick close to shores and rivers so that they could hit all of those little towns, and in the process discover just where all the natural safe alcoves and smooth beaches are. This means they could pull up into safe places and/or anchor down during major storms such that they might lose a ship here and there, but losing the whole fleet with all hands would be much less likely than for a deep sea fleet. Even with all their ships in one spot. [Answer] Anti trust laws in the time you are referring to were as an abstract concept as the human right declaration: whoever had a vantage position in a trade, defended and affirmed it with force, not excluding active sabotage if needed. Look at the competition between the sea republics in the Mediterranean sea, or at the competition between Spanish and British fleet. It's highly unlikely that a small trade would be allowed to stomp the feet of large corporations and companies. For one, they might be uncapable of satisfying the demand of a specific port (you mention the fleet is small). And if by pure luck they satisfy it, whoever has major interests in that port will make sure that suck luck won't strike again. Ship can sink, sailors can get stabbed when leaving a brothel... The only way to make it profitable is that they only know how to pursue a specific route and there are no suitable alternatives to that route. This is how the silk road worked, until the sea route didn't become more reliable. [Answer] As the other answer says, you need to go big, in order to compete with other companies and negotiate with locals. But that's not the only problem. Sailing can be very lucrative but is also very risky. That's not a problem with a big fleet, as the losses (sunken ship in a tempest, pirates, conflict with the locals) are compensated by the benefits. For a company such as the East India Company it's not that much of a problem if you lose 20 ships while in the same time you earn enough to build 40 of them. But from the point of view of a single ship it's different. While the mathematical expectation are still positive vessel which is lost can make you go bankrupt. Basically, you toss a coin each time you leave the port. You need to be very lucky to do this for generations, and the nomadic way of life will prevent you from growing big [Answer] To be honest, i am unsure. Typically, trade arrangements (of a larger scale) are made between companies and their representatives on land. To sustain their lifestyle, your nomadic traders will need to make sales large enough that the profits of those sales pay at least for the voyage to the next harbor. They should normally have a net gain lest the first bad day ruin them. Every sale has to reap enough profit to pay for wear and tear on their ships, as well as provide food and commodities for the few hundred crew. I doubt they would be able to do that sustainably without contacts in the towns and cities they call at. Yet, this is world building, and this here is a reality check question. We only need to find a way to make it possible. It desn't have to work in every story, just in the one you are telling. So, in order for your nomadic traders to be able to make substantial sales in every harbor, they need contacts there. This could be explained if they routinely travel more or less the same routes, then over time they get acquainted with local merchants. To start it off, it probably began generations ago with a small boat and their crew that just traveled up and down the coast, and with some luck and skill, the family became richer and their fleet grew. So, while it might be difficult, yes i think it is possible to have a setup like that. [Answer] **It can work as a family, but not as the entire family.** Sailing on ships in the age of sail is risky. Men go out to sea and they die - beset by pirates or privateers or weather or lack of wind or whatever. In return, they're financially relatively high-payoff. That can work financially, but it doesn't cover the lineage requirements. At a genetic level, this works if what you're mostly throwing out there is men. They sail, they probably die young, but they have women in various ports that they come back to (and spend money on), those women raise whatever children they manage to spawn, and often those children (when male) go back out on the boats to repeat the process (along with other young men drawn from overpopulated farmland). It mostly works. In a family, though, if the ship goes down, you don't just lose the men. You lose the wife and kids, too, and that's the end of the line. The family might get lucky, but it won't *stay* lucky, and just about any loss is goign to be crippling. Further, if there's no central port, it gets much harder for the family to coordinate. On the flip side, you could much more easily have a situation where a family had some holdings on land in a single port that they regularly returned to, where their children were born and raised, and so forth. It gives them some more stability, and a place to convert shipborn (and therefore at-risk) holdings to landside (much more secure) advantages. Possibly based around a "Familyname Importers" shop? Certain kinds of goods can get a much better price if you're willing to hang onto them for a while and sell them retail a bit at a time. [Answer] This small company is an opportunist which is not afraid of taking the risk While big trading companies run established trade routes, small actors can fill the niches that remain open. There is a new port where big companies don't go yet? A group of pilgrims wants to travel? No one else dares to sail in a storm season, even if profit is good? You can rely on this company to try these things. The risk maybe high, but the reward is also great. Sometimes a ship can be lost with all hands, and for a small company it is a big blow, but this company had learned to persevere. They have enough resources to replace the ship, and strong "family culture" which is imposed on all new members is somehow superior to what big companies have. [Answer] First of all I do not agree that this family of wandering traders, is an economically viable model of an organization. I agree with [@frish's answer](https://worldbuilding.stackexchange.com/a/174451/75049) and maybe change some of this clan's attributes: * The crews of the **Wandering Gypseas** consist of former slaves, persons with big depts in advanced countries, criminals who escaped conviction (maybe even criminals from other races) and any sort of "marginal" person in the rest of the civilized world. * The captains of the ships are all family members (inner or outer circle does not matter), and are all **biologically engineered** to withstand the severity of the sea. They are trained from their childhood in sea navigation, military tactics, swordsmanship, arms, and are the absolutely badassess of the ocean. + They only occupy an island in the edge of the world, that serves them as their hideout. Nobody knows of course of the island's exact location. + Because of the cruel ways of the clan, most countries do not wish to trade with them. (only disadvantage I could find, if you want to balance this Clan :) ). ]
[Question] [ I would like to have giant sand worms similar to the ones in the 'Dune' novel. What should the planet be like so that they are realistic? Giant sand worms are roughly 100m long and 5 meters in diameter. They can burrow/ dig through sand similar to earth worms, they don't need to create permanent tunnels, their tunnels can collapse after them. Their diet consists of some tiny critter in the sand, so they digest the sand and filter out the critters, similar to how whales filter tiny krill out of the water. On earth a creature like that can't exist because sand would just crush them and digging through harder materials takes way to much energy (there was a question about that here recently). So let's change the planet to make them realistic. I don't care about whether this species could have evolved, it is sufficient that they can exist as is. The planet doesn't need to be suitable for humans but that would be a bonus. Some parameters that could be changed: * Lower gravity should help a lot because sand becomes less heavy but I can't put numbers on it. * The atmosphere can be denser or thinner, atmosphere composition and temperature can be adjusted but I don't know whether that would change anything. * The sand: Sand grains on mars are about 1000 times smaller than on earth (by diameter), even gravel with a diameter of 10cm on average could still be sand. Not sure what works best for digging. * Shape of the sand grains: polished round almost spherical for low friction or complicated shapes for lower density? * Chemical composition of the sand: sand is usually some silicate but if nitrogen snow at -210°C is the only way to go then so be it. * Whatever else needs to be changed to make giant sand worms. [Answer] **Fluidized bed world.** [![fluidized bed hot tub](https://i.stack.imgur.com/EJ3gq.jpg)](https://i.stack.imgur.com/EJ3gq.jpg) <https://www.youtube.com/watch?v=My4RA5I0FKs> This guy was sitting on a hot tub full of sand. When gas jets underneath were turned on, he sank into the sand. This is called a fluidized bed. <https://en.wikipedia.org/wiki/Fluidized_bed> > > A fluidised bed is a physical phenomenon occurring when a quantity of > a solid particulate substance .. is > placed under appropriate conditions to cause a solid/fluid mixture to > behave as a fluid. This is usually achieved by the introduction of > pressurized fluid through the particulate medium. This results in the > medium then having many properties and characteristics of normal > fluids, such as the ability to free-flow under gravity, or to be > pumped using fluid type technologies. The resulting phenomenon is > called fluidisation. > > > When the sun comes up on your world (or some other form of heat appears - tides? geothermal?), beds of liquid (or solid) materials under the sand volatilize and the sand becomes fluid. Methane clathrates would work, or CO2, or a number of other substances depending on the temperature and pressure of your world. I think phase change from gas to liquid would be best. When the bubbles start, the sand becomes fluidized and the sandworts start moving. At night all of the gas that has bubbled thru condenses and rains down onto the sand, traveling back down as the fluid to the reservoirs below. The sandworms are stuck where they are, and they wait for morning. This percolation of stuff thru the sand also offers a possible energy/carbon source for the primary producers that the worms eat. [Answer] * low gravity would certainly help. The less the better. But then comes the question of atmosphere: do not count for less than 1/3 of g to have atmosphere more than 1/10 of Earth. Mars with a magnetic field is a good candidate * Atmosphere would matter a lot since worms need to breathe. You want low CO2 (<2%), much O2 (15-30%) and heavy atmosphere (due to low gravity), so "filler gas" (85-70%) should be of some heavier compound (argon, or some organic gas? - I can't give advice here) * Sand on Mars is the same as on Earth, but *sand in air* there much thinner due to low atmosphere pressure (it can't lift heavier particles). So there would be a surface layer of denser and finer sand few meters deep and then "normal" sand. For digging is better have clay - it can support itself. As for sand, any would be bad for digging, but bigger-grain sand would allow easier breathing and slightly deeper digging. Smaller-grain sand is better for "filtering" food. So middle-size grain is preferable. * Shape of sand doesn't matter much. Rough sand is better it would better hold and distribute weight. * Good old silicon sand is good enough. All exotics would be too speculative. Worms need a biosphere to live in, and the only one we know is based on a rocky planet. * Main problems of giant sandworms is the weight of the sand above, water, food and air (in that order). They should have very slow metabolism (like move 1 meter/hour) in "standard mode" to preserve energy and avoid places, that can be, say, flooded with water or more sand. They also would tend to be narrow and long. No more than a meter across at max (but some exaggeration is ok). Dune worms are completely unrealistic without the magic they had. [Answer] Here is a link to a post asking about the largest possible size for a giant serpent or worm: [What theoretically is the limit or max size and length for a serpent/worm before they get crushed by their own body?](https://worldbuilding.stackexchange.com/questions/160805/what-theoretically-is-the-limit-or-max-size-and-length-for-a-serpent-worm-before/160859#160859)[1](https://worldbuilding.stackexchange.com/questions/160805/what-theoretically-is-the-limit-or-max-size-and-length-for-a-serpent-worm-before/160859#160859) You might want to consider how big you want your sandworms to be, because I can believe there should be a size range where they could move through the sand or sand like substance in your world, and another size range where those sandworms could get enough food to eat, and another size range where those sandworms would not be crushed by their own weight like whales out of water. And you should hope that all three of those size ranges overlap to form a somewhat more restircted size range, and that it includes a size that you consider sufficiently impressive for your sandworms. ]
[Question] [ I am working on a setting in which there are a very limited number of human females remaining, and the intent is to repopulate as quickly as possible. Given a modern level of medical technology, what is the maximum number of viable eggs that could be produced by one woman assuming she is somewhere around 25 years of age and reproductively healthy? EDIT: Just realised I should clarify, in this setting there are artificial wombs available, so it is not a matter of how many pregnancies are possible, just how many eggs could be produced per woman for the purposes of in vitro fertilisation. [Answer] **260,000 embryos** Remember, women are born with all the eggs they are ever going to have, and they don't make any new eggs during their lifetime. [Women are born with approximately two million eggs in their ovaries](https://www.infertile.com/beating-biological/), but about eleven thousand of them die every month prior to puberty. If you were to extract all those eggs at a young age, and had some kind of artificial womb to grow the babies, then you could have a lot of babies. Now, if you waited till she was 25 to harvest the eggs, then it's going to be a lot less. 11,000 a month till age 12 = 1,584,000. Then 1000 a month from 12 to 25 = 156,000. So you are looking at around **260,000**, give or take a few. [Answer] Recent research has suggested that the conventional wisdom is wrong and that [people can generate new eggs within their bodies](https://www.theguardian.com/science/2016/oct/07/evidence-suggests-womens-ovaries-can-grow-new-eggs) that were not in there when they were born. On the other hand, some other smart people have looked at the research and the evidence and remain quite dubious. On the gripping hand, I don't see any data on the rate of egg creation, which is sort of what your specific question requires, so you're still kind of on your own. [Answer] While I don't have actual numbers for you, the method will be to induce maturation of multiple eggs in a given ovulation cycle, then harvest them. Harvesting whole ovaries doesn't work. The eggs have to ripen. We don't know how to do that. Not all women will be able to produce eggs at all, others will react badly to the medications and surgeries, and number of eggs as well as endurance in number or frequency of harvesting cycles will vary woman to woman too. For the purpose of obtaining a decent average, you need the following information: Number of *usable* eggs obtained X number of harvesting cycles in any given time period Don't assume one cycle per month. It may take longer to get things going hormonally. And bodies need to rest. The few citizens of your world who are able to provide eggs aren't resources to exploit. Don't assume that if it's safe to do a harvesting cycle, say, every 3 months, that this means 4 times a year times the number of years the woman remains at peak fertility. It doesn't work like that. There may be a maximum number of cycles someone can endure. A lot of people are saying things like, well at least you can get one egg per month. But you can't. Remember, the eggs don't just come out like a chicken's. You want a viable human egg, you have to perform surgery. Don't need a lot of cutting, but it's still invasive. You really want to do that every month? For your research, focus not on women undergoing fertility treatments but on women who donate (or sell) their eggs. Not all women using fertility treatments to increase egg production will have their eggs harvested for IVF or the like. So in those cases, you don't want maximum egg production. Also, women undergoing fertility treatments are more likely to be older and they will usually have diagnosed fertility issues. So, even with the same treatments, their egg production might be lower than that of a young healthy woman donating her eggs. I found this site that describes the process (and side effects... Yikes! Tons!). Perhaps you can call them and saying you're researching for a novel (or whatever it is) and would they mind telling you the range and average number of eggs harvested, how long between harvests, and how many times someone can safely donate. <http://web.stanford.edu/class/siw198q/websites/eggdonor/home.html> [Answer] <https://www.rogelcancercenter.org/fertility-preservation/for-female-patients/normal-ovarian-function> You start with about 1 million eggs at birth but these decline per month. At puberty you have about 300.000 eggs left. In the 30 to 40 years after puberty these are also depleted. This means at a "worst case" you lose about 10.000 eggs per year, assuming puberty for women starts around 12 years (again keeping it low for a worst case scenario) you would have 170.000 eggs remaining. So given enough artificial wombs, you harvest the entire ovaries and use techniques to have a 100% success rate if maturing and infecti... I mean fertilising the eggs with male DNA, you would have a pretty awesome growth. Edit: Willk in the comments noted this source: fertstert.org/article/S0015-0282(17)32178-7/fulltext. Which mentions a current-day method of harvesting eggs. Such a method, if not a more advanced due to the technology seemingly available, could be used for the harvesting. [Answer] Assuming a woman is fertile from age 13 to age 48, producing one egg per month, she can produce about $12 \cdot 35 = 420$ eggs. If you take her from age 25, this means about 276 eggs. [Answer] I wasn't sure if you could just take them all at once, but someone said in comment elsewhere that you cannot. I leave the route where you can below in case OP wants to go that way, especially since there is some advanced technology. But going the route where you cannot... For each woman who wants to contribute to this, I will assume the slowest normal production of approximately 1 per month. In 10 years, that should lead to greater than 100 children. Approximately half of them are themselves female, and at approximately that time those new females can contribute as well. For each one of them who does, the same pattern continues. So worst case scenario is that every decade the population multiplies by approximately 100. In 2 decades, that is a factor of 10000, 3 decades is 1 million, 4 decades is 100 million, 5 decades is 10 billion which is more than are on Earth today. And there will be no problem whatsoever with fertilization from males at this rate of population growth. So a planet can be completely repopulated, at least by the numbers, in 1 person's lifetime. But remember, that is from 1 starting woman who wants to contribute. For 100 starting, subtract 1 decade from the repopulation. Further, some people suggest that you should have tens of thousands of people minimum for a repopulation due to genetic diversity, so if you have that then subtract *2 decades*. The planet has plenty of population in 2 decades, is fully repopulated (to today's level) in 3 decades. In 4+ decades it has a huge number. --- **Previous Answer (the fast track to full repopulation in 2 years)** My initial reaction was the same as in Andy's answer (though I did comment there about how I was not sure if you could just take them all at any time), but since your purpose is planetary repopulation you can go a step further. 1. That is per woman, but only the women who contribute. Some might not. 2. That is just the first generation of repopulation... So you do your first generation of repopulation, and you have approximately (number\_of\_women \* 100000) new people now, but approximately half of them will be female as well, so if this is the route you are going, in just 1 year you can do this again with females which possess even more eggs, on the order of a million. I will assume for a moment that "a very limited number of human females remaining" is 10. Let us ignore genetic diversity for a moment, as this calculation is just to make a statement about population growth rate. So we have 10 females. 10 \* 100000 = 1 million babies next year Then you collect the eggs from the new females, approximately 500000 females at approximately 1 million eggs each... 500000 \* 1 million = 500 billion new babies that year So in only 2 years you have gone from a few humans to 500 billion; that is already 100 times more people than are on our planet today. And if you did the same thing again the next year, there would be... what's after a trillion again? Whatever, a huge number of people. **However!...** Those eggs need to be fertilized, so now you have to ask the same kind of question about males. They generate a lot of sperm all the time, and each 1 could fertilize a very lot of eggs, *but not a million of them all at once*. So you would need to fertilize them in large batches which would slow this all down a bit. However, this slower rate is still exponential crazy-super-high rate of population growth, and once again total repopulation would not take long at all. ]
[Question] [ In my story, flying creatures rule the sky. These creatures are usually tiny like an eagle or a vulture compared to huge (cumulus/cumulonimbus) clouds and these creatures always hunt and hide as groups. 1. Can clouds be used as their hiding places? 2. Is it possible to detect them if they are hiding in such huge clouds with our current technology? 3. Is there any way for these creatures to remain undetectable even when our technology is used? [![picture of different types of clouds; cumulus is below 6,000 feet and cumulonimbus is near ground to above 50,000 feet](https://i.stack.imgur.com/wbBOi.gif)](https://i.stack.imgur.com/wbBOi.gif) [Answer] > > 1.Can clouds be used as their hiding places? > > > It depends on what is used to look in the sky. If we are limited to visible radiation, a cloud can be a good hiding spot. To certain radar, instead, clouds are transparent. Thus they will offer no hiding. > > 2.Is it possible to detect them if they are hiding in such huge clouds with our current technology? > > > Yes, as long as the cloud is transparent to it (i.e. Radar R band) > > 3.Is there any way for these creatures to remain undetectable even when our technology is used? > > > Against radar a stealth shape, minimizing radar cross-section, would help reducing visibility. Another help could come from their size: if they are small enough, the radar wave will not see them. But be aware, if they are too small it's hard for them to rule the sky. [Answer] My answer will focus only on your first question: *Can clouds be used as hiding places?* # Yes, but not always, and not reliably, because... ### Clouds don't last forever. Cumulonimbus (thunderstorm) clouds [build and then dissipate](https://www.youtube.com/watch?v=tVP1ZgD75tE). If you're trying to hide yourself in one, sooner or later your camouflage will vanish from around you. ### Thunderstorm clouds aren't fun to fly in I'm a pilot, thunderstorms are Not Okay to fly in. [In their official publications](https://www.faa.gov/documentlibrary/media/advisory_circular/ac%2000-24c.pdf) the FAA says things like: > > ...extremely hazardous... > > > ...almost impossible to hold a constant altitude... > > > ...attempting to maneuver greatly increases stresses... > > > ...penetration of any thunderstorm can lead to an aircraft accident and fatalities... > > > ### What the...hail? That's right! Thunderstorms also feature hail. Hailstones have killed sheep before. *Sheep.* If it can kill a sheep it can kill an eagle (or equivalent eagle-sized flying creature with hollow bones) ### Depending on what latitude your story takes place in, there's also ice! That's right, in the wintertime you won't get cumulonimbus clouds. Instead, you get to deal with [freezing rain](https://www.insideottawavalley.com/community-story/4331408-ice-storms-can-have-lethal-effects-on-birds/), which will form on the wings of your flying creatures, adding weight and hindering their ability to fly. [Answer] ## Yes Ok, before I list my sources, I need you to do these following steps. **I cannot guarantee your safety if you do not follow them:** 1. Go to the kitchen (or grocery store) 2. Get a tinfoil 3. Make yourself a hat 4. Wear tinfoil hat before reading any further You can use infrared filter to spot many hidden objects in the sky as shown in this following video: <https://www.youtube.com/watch?v=mnYvfZTN2jo> So, to answer your specific questions: > > 1. Can clouds be used as their hiding places? > > > Yes, but only for naked eye. These creatures will not fool simple infrared filter on a camera. (Strong assumption made here: These creatures emit heat) > > 2. Is it possible to detect them if they are hiding in such huge clouds with our current technology? > > > Yes, totally. Any person walking the Earth can spot them with relatively cheap accesories > > 3. What is the optimum body shape for them to be able to hide in this way? > > > Look as "cloudy" as possible. But that does not fool anyone: [![Dragon from the question caught ALIVE on vieo!!!11!!!11!!](https://i.stack.imgur.com/Yy3c6.png)](https://i.stack.imgur.com/Yy3c6.png) Source: <https://www.youtube.com/watch?v=UsP9zkweVy4> , edit mine. And I do not even care at this point about that video's upload date... ]
[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/96060/edit). Closed 6 years ago. [Improve this question](/posts/96060/edit) Specifically, I'm looking for an event or catastrophe which 1. happens quickly (climate change is too slow, I mean a full on cataclysmic middle-of-the-night sort of deal) 2. leads to a near-extinction of the human race but 3. allows for quick social recovery (people living in small-scale communities) 4. preferably drives people to leave cities (due to war or natural dangers or anything else) Ideally people would have access to basic amenities, and could sort themselves out somehow for electricity, but not have contact to people in other parts of the world (radio and internet are gone). I've considered gamma bursts, nuclear war and ecological/natural catastrophes, but I feel like they leave too much messy aftermath (radiation and such) or just feel a bit overdone (ooh massive tidal waves, shocking) Science people, any ideas? [Answer] **1-2 punch**. 1. **Plague**, to knock them down. 2. **Religion**, to keep them down. I was reading about the Plague of Justinian and the dark age that it produced around 600. Lots of people died. No-one worked the land. But what really brought it home to me was this map, which I have taken from [By Steppe, Desert and Ocean](https://www.world-archaeology.com/issues/by-steppe-desert-and-ocean/). [![maps of cities before and after plague](https://i.stack.imgur.com/U6yiE.jpg)](https://i.stack.imgur.com/U6yiE.jpg) These maps show the sizes of cities before and after the plague. Look at Athens. Imagine living in that city - you and your family in one wing of a mansion near the old wall. You send your kids to pick fruit in the overgrown gardens of the other abandoned mansions on your street. The empty city stretches out, reminding you of past glory. Plague is good for knocking down civilization. But why did Western Europe stay down for another 500 years while the Muslim world blossomed? **Religion.** It is debatable whether the Catholic church slowed the advent of science in Western Europe. But it is plausible. For a story, religion is tailor made to slow down the advance of civilization as much as you need it to slow down. A plague would fracture society. One can see in our world today the seeds of the sorts of things that might follow - people who suspect evil motives on the part of vaccinators, persons who think AIDS is a plot to exterminate black people, people who blame epidemic disease like Ebola on witchcraft. Historically plague and epidemics led to an enthusiasm for [self-flagellation](https://en.wikipedia.org/wiki/Flagellant) which can be included in some incarnation in your post plague religion. Ramp these things up in the context of fear, chaos, societal breakdown pre-existing suspicions and there is your religion to keep society down as long as you need it down. [Answer] The two requirements of "middle-of-the-night sort of deal" and "[don't] leave too much messy aftermath" are kind of contradictory, but they still leave a few possibilities: * handwaving (e.g.: aliens arrive and decide Earth is too crowded). * some *serious* sun flare able to *kill* whoever is found unprotected (something slightly less severe than Niven's "[Inconstant Moon](https://en.wikipedia.org/wiki/Inconstant_Moon#.22Inconstant_Moon.22)"). * some military grade virus gone astray in the wild generating a 95% population death. * Nuclear winter due to some super-volcano continued eruption. In any case anything stopping overseas commerce for longish (months) periods is going to be utterly destructive as almost *no* region of this planet is self-sufficient food-wise (surely no urban areas anywhere). Re-booting civilization is not going to be easy as lots of different materials and tools are necessary to sustain our current production style. If reboot can happen quickly that's good, otherwise, if current infrastructure is allowed to "rot" we may not have the materials needed to rebuild as all "easily accessible" mine sites have been depleted long ago and what we are currently mining needs high technology. Some materials may be scavenged in scrapyards and similar (e.g.: copper), but others would be difficult to separate (e.g: some rare earths, tungsten, etc.) [Answer] **Viruses are nasty things** We recently saw [Ebola](http://www.who.int/mediacentre/factsheets/fs103/en/) kill a vast number of people in West Africa. It spreads via direct contact and contact with body fluids and contaminated surfaces. [Norovirus](https://www.nhs.uk/conditions/norovirus/pages/introduction.aspx) is more aggressive when it comes to spreading, it can be spread by contact and by air and can hang around for days on surfaces on which it settles. Gestation in hours, it can scythe through schools and hospitals. It's merely nasty (I've had it, it's horrible), rather than fatal, the instruction to people with norovirus is to stay at home because it's so infectious. Take something that's a mix of the two, ebola's fatality rate with norovirus' infectiousness. Do you tell people to go to hospital or stay away? Merely breathing the same air as an infected person can kill. Add a prolonged infectious period even after recovery (ebola remains active in semen) and the ability to survive for considerable time out of the body, and you'll kill a lot of people. Entire cities may be abandoned for fear of being too close to too many other people. People will die from disease, from loss of infrastructure, from curable and preventable conditions due to the risk of going to a hospital. The people who stay in the city will starve, those who leave will end up carrying the disease to new places and pick up even more diseases along the way. As with any disease, how many you kill will depend on the response and how fast it spreads before it's noticed. Deep rural areas may be unaffected, there will be survivors, but entire major cities will be lost. **Knocking technology back** You've lost most medics and probably medical researchers, the people who are determined to find a cure and keep going back to work, it would only take one or two slips to kill off the staff of a hospital. Non-critical workers may be instructed to stay at home under quarantine regulations but that still leaves critical workers exposed. Given how fast freshers' flu spreads through academia, you've probably lost an entire generation of students and academics. You may even have lost an entire generation of children, norovirus regularly shows how fast it can spread through a school. One of the kitchen staff ill in Parliament? There goes the government. The list goes on. Modern medicine gone, critical infrastructure gone, leadership gone, the people with the knowledge of how it all works gone, population drop to the point where there's no critical need to put it back together again. [Answer] It looks like you are looking for a '[cosy catastrophe](http://tvtropes.org/pmwiki/pmwiki.php/Main/CosyCatastrophe)' scenario set up in a [near-future](/questions/tagged/near-future "show questions tagged 'near-future'"). As others mentioned, a plague would be the least messy way to get rid of the majority of the world's population. How about it being an unforeseen side effect of a rejuvenating treatment? Those few who managed to survive fully benefitted from the treatment and their lifespans greatly increased. That would be very helpful for rebooting the civilisation and establishing a social order. The cosiness would depend on a degree of automatization and robotization. The closer your world to ours the more devastating will be the aftermath of any catastrophe. Developed countries will be hit the most since the majority of their citizens lost touch with the land and are very much incapable of fending for themselves. In the worst case scenario, they will end up in a stone age. I believe that 100 years from now the situation could be very different. If the majority of production is highly automated and relies on 'green' energy (solar, wind, or equivalent) the survivors can have very comfortable lives. It might be interesting to explore a world where machines take care of humans who lost the knowledge of building those machines. [Answer] I'd say a suitable event would be a super volcano eruption, or a asteroid hit. both would create a huge amount of ash/dust, that would fill the atmosphere, making the air hardly breathable. In order to continue their existence the remaining population would have to cut down on pollution heavily, power plants as we know them today would no longer be viable. solar power as well would not be sufficient, doe to the dirt in the atmosphere. the only way to continue the survival would be to start from scratch. and start innovating in new directions. In this scenario the population would still be able to generate some electricity mechanically, from maybe wind, or flowing water, but it would not be very efficient...(Water dams still do exist, but the infrastructures are all heavily damaged, people could perhaps build cities around those, to at the very least supply themselves with the required power). [Answer] I would go even further than ZioByte. The Options he listed are good, but i think what is necessary for your situation is a combination of those for the scenario of being set back by hundreds of years to be realistic. > > * handwaving (e.g.: aliens arrive and decide Earth is too crowded). > * some serious sun flare able to kill whoever is found unprotected (something slightly less severe than Niven's "Inconstant Moon"). > * some military grade virus gone astray in the wild generating a 95% population death. > * Nuclear winter due to some super-volcano continued eruption. > > > Imagine a solar flare causing an EMP-like destruction of all unprotected technology while also causing natural disasters to destroy the cities humans build. The super volcano would work too, since it would drastically change the climate and the general situation so much people would have to reinvent the technology they had. The results should be: * the majority of **technology is destroyed** * **people would flee the cities** due to natural disasters, lack of supplies due to chaos preventing goods from being transported * **most people would die**, thus making it necessary for every area of the world to start anew with the few people and the knowledge they have You could also combine the virus with the natural disasters or the solar flare, but that will probably be hard to build into a realistic scenario. Maybe virus + aliens would work. [Answer] While some of the other answers touched on this in general, the subject has come up very recently, due to world events [Electromagnetic Pulse from Nuclear Weapons](http://www.dailywire.com/news/22236/experts-warn-congress-north-korean-emp-would-kill-ryan-saavedra) > > Two electromagnetic pulse (EMP) experts warned Congress on Thursday that North Korea is capable of executing an EMP attack over the United States which would send the U.S. back to the stone age and would lead to the deaths of 90% of all Americans within one year. > > > [Answer] # Why not plague? I think all the other answers are missing something important. Plagues kill people, but not societies. Whoever is left will be left with as much of the capital of the prior civilization as they can continue to maintain; all they will have lost really is: * labor * skills * mouths to feed Make no mistake, this is bad, and certainly will cause a civilization to falter, but you really don't lose capital, let alone technology (by which I mean the knowledge of production processes). This is especially true today with the internet. In zombie apocalypse scenarios, the real problem is that zombies pose an extreme security threat, requiring people to devote huge portions of their economy to counter-zombification, or what we today would call "defense". # Communism As long as you have about 50 years: communism. Not wimpy, post-Stalin Soviet-style communism where you still allow black markets to thrive in the production of goods behind the Kremlin's back, but [Khmer Rouge](https://en.wikipedia.org/wiki/Khmer_Rouge), [DPRK](https://en.wikipedia.org/wiki/North_Korean_famine), [Great Leap Forward](https://en.wikipedia.org/wiki/Great_Leap_Forward), [Holodomor](https://en.wikipedia.org/wiki/Holodomor) Communism. You need to destroy the social norms that say that wealth creation and capital accumulation are good. You need to destroy the price system that allows for an efficient allocation of goods, and control all production from the top. Encourage the sentiment that if your neighbor has a bigger house than you, you can just accuse him of "[counter-revolutionary activity](https://en.wikipedia.org/wiki/Campaign_to_Suppress_Counterrevolutionaries)", and being a [Kulak](https://en.wikipedia.org/wiki/Dekulakization) and then once his brains are spattered on the wall, you'll be free to move in. The stronger your communism, the greater your degree of economic and [technological](https://www.reddit.com/r/Jokes/comments/4djg89/what_did_soviet_russians_use_for_lighting_before/) retrogression (except in [military technology](http://www.newsweek.com/north-koreas-kim-jong-un-starving-his-people-pay-nuclear-weapons-573015) of course). Just when you think things are getting really bad is [not the time to go soft](https://en.wikipedia.org/wiki/New_Economic_Policy). It's probably those damn counter-revolutionaries sabotaging the Party anyway! Crack down [harder than ever](https://en.wikipedia.org/wiki/Collectivization_in_the_Soviet_Union). If you throw in an [agrarian flair](https://en.wikipedia.org/wiki/Agrarian_socialism), you can really accelerate the technological retrogression, as you [kill most of the artisans and engineers](https://en.wikipedia.org/wiki/Khmer_Rouge_Killing_Fields), and move whoever is left to the countryside at gunpoint. I'm sorry if this doesn't quite fit your specified timeline, but look how much the [Khmer Rouge accomplished in 4 years](https://en.wikipedia.org/wiki/Cambodian_Genocide)! There are definitely other social manipulations that could work, but few are as effective as the abolition of private property, and the eradication of social norms necessary for commerce. So far, we've only had experiments this on a small scale, like [China](https://en.wikipedia.org/wiki/Maoism), but if you spread it over the whole planet, you'll get to crank all the bad parts up to 11. [Answer] I can not answer your question about what apocalyptic event could **cause** this, but I can say what apocalyptic event would **end** it. It's time to take the gloves off on this 'clean apocalyptic' thing. There are **7,500,000,000** humans, give or take a few, on earth. You are talking about **most** of them suddenly dying. Not vanishing, not disappearing, but dropping dead. Leaving dead bodies behind. Imagine a stadium with 40,000 people, all dead in their seats. They just stay there, rotting. Imagine a shopping mall, where everyone has just dropped dead. No one removes the bodies. There are 25,000,000 people in Beijing alone. All dropping dead overnight. No one collects the bodies. Now, how about seven **billion** dead bodies, all at once? Let's look at what happens to just one dead body. Maggots set in. Blowflies lay eggs. Roaches take up residence and lay eggs. Worms take up residence. Rats come to dine. All of those pet cats and dogs, now without owners who provide their food, seek out sustenance. This is happening to not just one body, but **seven billion bodies** all at once, all rotting and being consumed. And this is just the **human** bodies. Think about all of the domesticated animals - cows, pigs, chickens, in industrial food factory farms? No one takes care of them, they die. By the millions, if not billions. And they rot, or become food for predator animals, insects, bacteria, and such.. I have absolutely no idea of what apocalyptic event might cause it, but I can tell you what apocalyptic event would **follow**. Not just the plague, not just some bacterial or viral infection, not just some biological weapon, not just some health crisis, but **every** disease known would run rampant, unconstrained. No medicines, no medical facilities, no doctors to alleviate it. Malaria, diphtheria, dysentery, lyme disease, Necrotizing fasciitis, legionnaires disease, **all** of them **all** at once, would become epidemic. No sanitary facilities. No sewage treatment. No garbage collection. Rotting food, bodies, feces stay where it lies. No quarantine. Cats, dogs, coyotes, rats, would prowl every street, every home, every store. Every pet, now a feral predator. Unrestrained reproduction of those not neutered. Untold billions of tons of food would go rotting in stores, houses, warehouses. Bacteria, viruses, mold would cover everything that humans inhabited. The stench would be unimaginable. The worst of the slums of Calcutta, on a global scale, but without living humans to put up even a basic defense. No 'perimeter' to contain it. Every imaginable disease carrier - flies, mosquitoes, rats, mice, bats - unrestrained and uncontrolled. We are not talking about a 'clean' event - there can be no *clean* apocalyptic events (unless these billions of bodies, their pets, and warehoused fresh and uncanned packaged food just disappear). We are not talking about any surviving humans dealing with the few humans you posit would remain, we are talking about these very unlucky humans dealing with every imaginable onslaught of predatory animals and disease. There would be no 'Ideally people would have access to..'. There would be no **ideally** at all. There would be rot, decay, and disease on an unimaginable continuing multiple apocalyptic scale, not just **one** apocalyptic event. [Answer] Building on what @ArtificialSoul answered (too long for a comment): As you say, @ArtificialSoul, the majority of technology would be destroyed, including the computers holding a vast store of easily accessed information. Left would be books stored in libraries (public, educational and private), but people would be focusing on knowledge needed to survive, like how to farm or build a cart or just basically stay alive. And since so much time will have to be dedicated to survival, there will be very little opportunity to somehow preserve knowledge that is not immediately useful. People would have to disperse into smaller, rural, largely self-sufficient communities which are most importantly close to the greatest source of their survival - food. I think a massive solar flare kicking off a myriad of smaller natural disasters and isolating people would be sufficient to reduce the population by 90 or 95 percent, as many people who survive the initial disaster would die from illness, starvation or even be killed off by one-another in the ensuing anarchic state. Thus releasing "the Virus" would literally be overkill. People might be able to get some basic amenities like electricity going but only on a small scale, and only if they happen to be near readily available structure for generating such. Preppers would of course be entirely vindicated and would likely be wonderful resources of knowledge and what limited technology would be salvageable. [Answer] Now, those ideas don't happen over night, but they are moderately quick. * Plastic-eating bacteria that is spreading uncontrollably in combination with something else. Or maybe the bacteria also makes humans die very quickly. * A simple new deadly virus with a 100% mortality rate that would only leave humans on a few remote islands alive. * Massive simultaneous flood basalt eruptions that not only lead to a volcanic winter but also poison the atmosphere, something like the [Laki-eruption](https://en.wikipedia.org/wiki/Laki) but on a much bigger scale. Generally I would just use a combination of two different things. Like gamma ray burst and plastic-eating bacteria, or deadly virus plus volcanic eruption. ]
[Question] [ Imagine I travel back in time ~500 years, leave a modern ship/boat log book in a cave and the log book was discovered today. Since the book was discovered after it was possible to buy it off the shelf it could easily be a hoax. For example, a log book that was first produced in 2015 traveled back in time ~500 years and was found in an unexplored cave in 2017. Would it be possible to conclusively prove that it is ~500 years old and not just a convincing fake? Assuming of course someone actually took it serious enough to try to authenticate it... If I wanted researchers/archivists *to suspect* it was really ~500 years old *but no way to prove* that it was actually ~500 years old what would I need to do? --- For the purposes of the question you can use whatever type of log book is easiest to maintain the balance between impossible to prove but good enough to suspect. As such the actual log book can range anywhere from a [spiral bound notebook](http://rads.stackoverflow.com/amzn/click/B00D3OR58A) to a [waterproof floating log book](http://rads.stackoverflow.com/amzn/click/1886028400). --- I didn't talk about the content of the log book initially because I wanted the focus of the question to be on the physical analysis/dating of the book. However since it has come up once directly and once indirectly in answers; the content of the book will support the true age of the book of roughly 500 years. The log contains the experiences of the time traveler and will have things that appear to initially contradict history but will be shown to be true (like describing an animal that doesn't exist but later is found to have gone extinct). The content is to be used as a hook to investigate if the book is a hoax, but **I want the lab tests to be inconclusive**. [Answer] Actually, there is much more carbon-14 in the air today than it used to be before we [pumped a lot of neutrons](https://en.wikipedia.org/wiki/Radiocarbon_dating#Dating_considerations) in the atmosphere in the 1960s by exploding atomic bombs on the surface. So if the paper is radiocarbon dated it will be found to come *from the future*. This will of course raise quite a few eyebrows, and the book will become an object of deep inquiry. [Answer] This is definitely possible. **Radiocarbon and Radioactivity Dating** Your notebook was manufactured in a post-nuclear society. Any iron or steel in the notebook (staples, coil binding) will contain tiny bits of radioactive matter. This is actually undesirable in certain cases, such as geiger counters. Your researchers could investigate the metal objects in the notebook. Now, they could posit that it is a hoax, due to the above discovery. This is the rational, normal reaction. It is at this point that they could test the other use radiocarbon dating to test the paper in the notebook. If the carbon in the paper has not been contaminated, then it will show that the paper is 500 years old. **Industrial Evolution** Five hundred years ago, books did indeed exist. They were even manufactured using the printing press. However, there have been enormous advances in the manufacture of books and paper in the intervening time. So, your notebook would be extremely easy to differentiate from period notebooks, not just through the material, but also through the design and aesthetic. The ink will be different, the font will be different, everything will be different. **My Thoughts** While you are free to do whatever you want in your world, I would posit that a huge majority of scientists or researchers would dismiss the notebook as a hoax, given no other information. It is up to you to provide a reason they spend time and funding on properly dating the book. Have it financed by a wealthy, interested party, or have it discovered by a scientist who happens to be open minded enough to give it a close look. Anyway, great question, I had fun answering it! Edit: I have become less sure that you could date metal used in the notebook. I actually have no idea about the half life of all nuclear particulate in steel production, and I am not sure how detectable any of them would be after 500 years. Furthermore, I have doubts about the ability of a random ships log to survive 500 years of anything. [Answer] Think of all the means to analyse e.g. [paintings](https://en.wikipedia.org/wiki/Art_forgery#Forensic_authentication) or documents to detect forgeries. Those could be applied to your book, and they would detect **anomalies**. * Bellerophon mentioned [carbon dating](https://en.wikipedia.org/wiki/Carbon_dating_the_Dead_Sea_Scrolls) in his comment. Trying to spoof this would be exceedingly difficult but not impossible. Take raw material with the desired isotope ratio and produce paper from it. This might first require turning this carbon into wood, i.e. growing plants in a sealed greenhouse. [Separating isotopes](https://en.wikipedia.org/wiki/Isotope_separation) has been done on much harder materials than carbon. * Chemical analysis could look at the inks and paper. * If the location is preserved/analyzed carefully, there might be e.g. a [stalagmite](https://en.wikipedia.org/wiki/Stalagmite) on top of the book. But this cannot prove the book is really 500 years old. The analysis might be *consistent with* a 500 year old book. But it could also be consistent with somebody *pretending* to have a 500 year old book. Now somebody looks at the book which *seems* to be artificially aged. Except that they can't quite reproduce how. [Answer] If you take any modern-day logbook, fill it using any modern-day ink, travel back in time and plant this logbook in a cave, there is no way researcher would believe that this is a 500 year old book. Even if all [dating techniques](https://en.wikipedia.org/wiki/Absolute_dating) agree that the age is 500 years, the book itself would be a dead giveaway it's a trick. But if you take an effort to make paper using 500 year old techniques, bind it into a book, just like it was done 500 years ago, prepare ink and fill out the book using appropriate language and style, that book will pass as genuine. If the book really aged for 500 years and there are no "red flags", it would be presumed to be authentic. You said nothing about content of the book though, and I suspect it should raise some eyebrows. [Answer] Some telltale signs are very hard to fake. Lichen grown on the up facing side. A pattern of mineralization of a down facing side. Accumulated bat excrements (sorry). Maybe even pollen from plants which are long since extinct. Of course it very much depends on the conditions inside your cave. [Answer] # Partially encased in rock If we assume the book can survive any and all sorts of environmental factors... have the book be partially encased in a [stalagmite](https://en.wikipedia.org/wiki/Stalagmite). Whoever finds it enthusiastically chops up the stalagmite and takes out the book. What you have then is broken evidence. If the book had been left in it could easily have been determined "Yup... that is a natural process. It **is** 500 years old". But now they find the discovery site broken, maybe even vandalized. It certainly appears that some of the fragments fit the book. But conclusions are uncertain. That is when people start doing fancy stuff, like radioactive dating. And comparing with a "fresh" example of the same product series, they will certainly find discrepancies, the most glaring one being: less radioactivity in the found book compared to the ones that did not time-travel. But if you then want to throw some confusion into the mix, make the time travel **add** some funny isotopes to the book. Then the investigators will be in the situation that the book in some aspects is less radioactive than it should be (more fitting a 500 year old book)... but in aspects it is **more** radioactive than it should be as well. For instance: while the contemporary books' metal parts contain [iron (Fe) with the usual mass distribution of isotopes](https://en.wikipedia.org/wiki/Isotopes_of_iron), your book could have a curious **surplus** of 60Fe. [Answer] If I wanted to make a book seem old I would take rag based blank paper from the last unused pages in quires of several old books. There are plenty of old book with nearly destroyed bindings that I could use to harvest pieces for the cover. If I wanted the book to last 500 hundred years I would NOT put it in a cave. That is far too moist. Is there anyway it could get in the between areas of a building undergoing renovation 500 years ago. I read about how a second story was added to a medieval building with arched ceilings on the first floor. Debris was used to fill in between the arches on the first floor ceiling and the floor of the second floor. Archaeologists found all sorts of cool stuff in the between areas that had not been touched in centuries. This included textiles. Even if the log book looked modern a scholar might be interested if the words were written in iron gall ink with a quill. Of course there are crazy people like me who have made ink and cut quills for writing but we usually try to use nice paper or parchment. The contrast of a modern log books and quill writing could intrigue a scholar. Using a quill produces writing that looks different from a ball point pen or even a fountain pen. Have you looked at the investigations on the Vinland Map? It will give you and idea of what suitably motivated researchers will do to authenticate a book and how many ways the results can be inconclusive. <https://en.wikipedia.org/wiki/Vinland_map> [Answer] If the book was produced in the modern era, there would be all sorts of other tells to this, not just the paper degradation and the quality... the paper making process has evolved in 500 years. Modern Ink will look different to an analyst than ink used 500 years ago. Not only that, both products are documented for crime purposes and there are databases that can identify where a piece of paper and pens were purchased based on unique qualities to that particular batch of paper or ink used in it's manufacture (The secrete service loves this because they get a lot of hand written threats and they do identify who wrote them and where they were when they were using them). On the note of Carbon Dating, inconclusive dating can be attributed certain events that make the test unreliable. For example, the Carbon-14 dating of the Shroud of Turin is still called into question due to the sample possibly having been part of a repair to the shroud and/or the Shroud was historically in no less than two fires and may have suffered damage that would affect the test (not to mention the use of candles, which are still a big part of Catholic Mass). Although these are scientifically not conditions that would change the dating by a millennium as claimed, it could raise doubt among those who believe it is real. Of course, if you need it be authentic or perceived as such by a skeptical community, you are overlooking a pretty big way to fool everyone: Your a time traveler! Why not go back in time 500 years, spend a few days or weeks hand writing the thing on authentic period parchment and with authentic ink so that when it is discovered in 2017, it looks the part because it is the part. If the source isn't yours, take a copy with you and hand copy it from that. Need it to be typed and not handwritten? Your in luck too! By 1517 the Gutenberg Press was 87 years old and was seeing widespread operation in Western Europe with an estimated 20 million copies printed using this invention. By the end of the century, that number would increase by a factor of 10! So, you can get period accurate ink, pens, paper, and type face for a modest fee and not have to worry about all of this. And if spending time in Medieval Europe isn't your idea of a stellar writing environment, well, again, you're a freakin' time traveler... take all the materials, come back home, and do the whole forgery while sipping on a coffee in Starbucks. Better yet, if you want doubt, stain it with have a hot chocolate and stain it with your beverage, because chocolate was still not widely available in Europe back then. Oh... and if this isn't something you think you can afford because of currency issues... well, change that coffee to a soda and once finished, extract the aluminum (it can be done with stuff found in a high school chem lab) take that stuff back to a point in time where Aluminum was more valuable than gold (yes... the Washington Monument is capped with an Ingot of Aluminum as a display of America's wealth. Napoleon would host state dinners on the gold plates... the Aluminum plates were for special occasions.). Really, if you have a time machine and aren't doing this, I don't know what to tell you beyond revoking your time traveler's license. [Answer] If the book contains and steel in its binding, staples etc, and if that steel was made after WW2, it will contain measurable traces of cobalt-60 from atmospheric nuclear explosions. After 500 years that $^{60}$Co will have almost completely decayed. If you wanted to fake this aging, it is possible but you would have to remake the steel part from [pre-atomic age steel](https://en.wikipedia.org/wiki/Low-background_steel). ]
[Question] [ [Lichen](https://en.wikipedia.org/wiki/Lichen) are a symbiotic organism that involves algae or cyanobacteria living inside a fungus. The algae produce energy through photosynthesis, while the fungus protect the algae from the environment and provide access to water and nutrients. In many ways, this relationship is similar to that of [corals](https://en.wikipedia.org/wiki/Coral) and photosynthetic dinoflagellates. I wish to create a forest of symbiotic mushrooms. The sun-facing surface of the mushrooms is permeated with a symbiotic photosyntesizer. Mushrooms, of course, can have a variety shapes and sizes with a diversity almost resembling a coral reef. Let us assume for the purposes of this question, that mushrooms' chitin based cell walls can be adapted to allow mushrooms to grow to several meters in height, at least. I will leave the maximum vertical height or horizontal cap spread of these mushrooms to the judgement of the answerer. My question: In what climate or biome would mushroom forests have the most competitive advantage against other plants? Secondary question: What sort of ecological relationships would these mushrooms develop with other plants? This question is strictly flora/plant based, more fauna questions to come. [Answer] While it's hard to say exactly where fungi would out-compete plants, I have some good news for you. There is one major zone on Earth where both algae and fungi dominate, and plants do not: *Below the Antarctic Circle* ## **Diversity Statistics** Antarctica currently contains 100 species of moss, 25-30 species of liverworts, and 2 species of flowering plants, with no trees or shrubs. Meanwhile, it has 250-400 species of lichens, which are included in its 1,100 species of fungi, and 700 species of algae. This is a huge difference. ## **Possible Explanation** Plants are heavily reliant on their vacuoles (water storage compartments within cells) to maintain structure and provide nourishment. In cold conditions, these freeze easily. This explains why the less structural *mosses* do better than upright plants in this environment, and why fungi do even better still. While fungi *do have* vacuoles, they are generally smaller in fungi species than in plant species. Fungi have stronger cell walls to compensate. **In short, plants freeze easily. Fungi don't.** ## **Realistic Size of Fungi in this Environment** This is your biggest problem. While fungi and symbiotes containing algae will out-compete plants in an extremely cold environment, they themselves may not be able to grow large easily. Your idea of stronger cell walls helps, but you may want to consider a method in which these fungi warm themselves (chemosynthesis, maybe?) in order to allow fast growth and metabolism. ## **Potential Ecological Relationships** These are not likely. Aside from the symbiotic processes between algae and fungi, or the interaction of fungi using mycelium under the soil, your fungi won't come in contact with many other organisms. Mosses could be plausible if they occupy or compete for the space that your mushrooms want. Of course, remember that even though photosynthesis is occurring, your organisms will want nutrients from the soil to grow large. This means your fungi will likely decompose other organisms to acquire them. [Answer] The big advantage of a fungus-microorganism symbiotic relationship is that there are more possible photozynthesizing pathways available. Plants use chlorophyll to generate energy from the sun. It is clearly effective, but it is restricted in the wavelengths that it operates on. [![enter image description here](https://i.stack.imgur.com/oQfoO.png)](https://i.stack.imgur.com/oQfoO.png) [Chlorophyll a](https://en.wikipedia.org/wiki/Chlorophyll_a) is universally present plants, algae, cyanobacteria, and prochlorophyta. [Chlorophyll b](https://en.wikipedia.org/wiki/Chlorophyll_b) is also present in plants, and the absorption spectra of the two plants are shown in the figure above. However, there are other chlorophyll types available. [Chlorophyll d](https://en.wikipedia.org/wiki/Chlorophyll_d) has a far-red absorption at 710nm, just outside optical range. It is present in red algae, which also has accesory pigments called [Phycobiliproteins](https://en.wikipedia.org/wiki/Phycobiliprotein) that have additional absorption peaks at 546, 566, 620, and 651. These are evolved for deep sea algae due to longer wave-length light penetrating farther in water than other parts of the visible spectrum. Another option is [fucoxanthin](https://en.wikipedia.org/wiki/Fucoxanthin), found in brown algae such as kelp with increased absorption in the 450-540nm range. On land, with lots of blue wavelength scattering due to the composition of the atmosphere, the plant's absorption peaks are a pretty good deal. However, underneath a canopy of trees, as in a rainforest, the light spectrum is different. Reflected light from green tree leaves is green, in the ~550 range. Plants are not optimized to utilize this diffuse light in the understory. According to [Denslow, 1987](http://artifex.org/~ecoreaders/lit/Denslow1987.pdf), photon incidence on the forest floor is only 1-2% of that from a clear sky, and plants do not utilize this light due to its spectral composition, instead relying on sun-specks that break through the leaves briefly for their growth. In this [paper](http://people.hws.edu/mitchell/oz/Papers/ParkerTer.html), gaps in a subtropical rainforest in Queensland caused by fallen trees have increased levels of blue-green and infrared radiation. In conclusion, I propose that a fungus-algae symbiote could evolve to use a rigid, chitinized mushroom platform to absorb diffuse light in a rainforest understory. The rain and high humidity would allow the algae to thrive, and the leaf litter from the taller trees would provide abundant decaying material for the fungus to utilize. These persistent symbiotes would have a competitive advantage against understory plants due to light absorption better suited to the available spectra and secondary energy generation from decaying leaf litter, an energy source that is available during the entire daily cycle, not just during daylight. [Answer] Fungi ordinary thrive where there is dead biomass and moisture, but it is too dark for adequate photosynthesis, such as caves and the sub-canopy levels of a dense forest. Direct reliance on photosynthetic symbionts really throws off that equation, because it forces them to be second best competitors with purely photosynthetic plants. The sort of place I would imagine would be best for a tall fungi forest would be in a delta of a continental sized river system (think New Orleans) in a location on a planet that is in the dark all or most of the time, but isn't far from the dark side-light side divide. This would be warmer than more distant points and would get first dibs on biomass crossing over to the dark side. Temperature-wise too far on the sunny side would be too hot, too far on the dark side would be too cold, the breeze exchanges near the boundary would be just right. This would provide ample moisture and biomass sludge flushed down the river system from the sunny side to feed them, but would suppress competition from photosynthetic plants. A place like this would also be prone to London quality fog on a regular basis which together with the mushroom forest would really add to a memorable atmosphere and mood for the place. Why would they get tall when they aren't reaching for the Sun? Perhaps the height would provide places for local fauna to take refuge during high tides at which time they would poop and/or die on the mushroom trees providing more nutrients. Height would also provide access to air for the fungi during high tides. [Answer] Maybe it doesn't actually have much to do with light as it does with nutrients. Say the mushrooms are [parasitic on other plants](http://www.mushroom-appreciation.com/types-of-mushrooms.html#parasite) and aggressively predatory. Their spores invade a forest, latch onto trees and begin sending their mycelia all over like vampiric fingers, spreading more mushrooms very fast, killing the trees off. After the tree dies the mushrooms begin feeding off their rotting remains and start growing taller. They don't have to get too tall since they don't need the sunlight, they just want to be high enough that the spores can get some distance. The honey fungus is one type of parasitic mushroom which is able to infect and kill healthy trees. One of its subspecies is the Armillaria ostoyae, which is thought to be the largest organism in the world. Mainly growing underground, the mycelia of this patch covers over 2,400 acres in Oregon. It's estimated to be over 2,200 years old. This parasitic super fungus, known as Armillaria Lamia, could also spread underground and not just through spores, attacking the trees at the roots and working their way up. Normal mushrooms do not photosynthesise, though there could be a secondary lichen that is symbiotic with the mushrooms. ]
[Question] [ I've been reading the book Nomad, and in it > > a binary pair of black holes is cruising into the solar system, and threatens to slingshot the earth out into deep space > > > That's got me thinking, is there any chance of survival beyond a few days/weeks when the atmosphere freezes? (Would it freeze?) Just off the top of my head, I suppose a nuclear submarine parked near some geothermal vents (where the water hopefully wouldn't freeze) could last until the food ran out. The folks on the ISS wouldn't have sunlight for power so they wouldn't last too long. Obviously we'd be looking at either nuclear or geothermal energy sources to keep us going, coupled with some closed loop life support systems. To be sustainable (both short term for food and long term for population), it'd have to be fairly large-scale. In The Martian, Mark Watney is nearly self sufficient. He'd need more space to grow food, plus some nuclear power would help. Would that system scale? We have the advantage of earth's mineral resources that may still be accessible to an extremely well-equipped band of survivors. Let's assume we have plenty of warning that the earth is going to be ejected (say decades). Is there any possibility for humanity to survive long enough for us to develop advanced enough technology for our own deep space-capable ships (so, permanently)? [Answer] Lets take a look at this mathematically: First off, take a look at [Earth's energy budget](https://en.wikipedia.org/wiki/Earth%27s_energy_budget#Incoming_radiant_energy_.28shortwave.29). The incoming solar radiation is $\approx 240~\frac{\text{W}}{\text{m}^{2}} = 1.73 \cdot 10^{17}~\text{W}$ total. Imbalance between incoming and outgoing is about $\left(0.60 \pm 0.17\right)~\frac{\text{W}}{\text{m}^{2}}$, so relatively insignificant. This means that Earth radiates about $1.72 \cdot 10^{17}~\text{W}$. Earth's oceans are a significant heat regulator for the planet, and contain about $1.4 \cdot 10^{21}~\text{kg}$ of water ([source](https://en.wikipedia.org/wiki/Ocean#Earth.27s_global_ocean)). This means a change of 1 °C in the oceans is equivalent to about $6 \cdot 10^{24}~\text{J}$ of heat energy. From this we have: $$ \frac{6 \cdot 10^{24}~\text{J}}{1.72 \cdot 10^{17}~\frac{\text{J}}{\text{s}}} \approx 3.5 \cdot 10^{7}~\text{s}=405\,days $$ **So it would take a little over a year for the ocean temperature to drop by *1 degree Celsius*.** For the purpose of the question, let's assume the majority of Earth's readily available heat is contained in the ocean, such that the ocean temperature directly correlates to the atmospheric temperature. This is an oversimplification, but not to far off (and in reality, the ground also stores a significant quantity of heat, so this will likely lead to an overestimate of how quickly the temperature drops). This result means we would actually have quite a bit of time (on the order of years) before Earth became unlivable. Likely, we would see an immediate drop in temperature such that the mean temperature becomes about the same as we would expect for nighttime temperature. After this, we would see a more gradual decline corresponding with the loss of heat from Earth due to radiation. People in northern latitudes or desert regions would likely be in immediate danger, but tropical regions would likely remain livable for quite some time, and you are not in danger of the atmosphere freezing for a couple centuries at least. The other immediate danger would be massive plant die-offs (due to lack of sunlight) followed by massive animal die-offs due to loss of food sources. The plant die-offs would have an interesting side effect of increasing carbon dioxide concentration in the atmosphere, leading to a stronger greenhouse effect and *reducing* the atmospheric heat loss. Given the relatively slow heat loss, we should have enough time to build enclosed habitats powered by geothermal energy (coal, oil, and nuclear are all still options as well, but if you are already underground geothermal is quite convenient). There would still be significant casualties, but the short term effects would be at least as survivable as a nuclear winter. Longer term (after about a century), the oceans would eventually freeze, followed by the atmosphere. At this point the surface would be completely inhospitable, and we would have to rely on underground habitats to survive. **So, given sufficient organization, yes, the human race should be able to survive.** [Answer] No, if we lose the sun, we are done for. Simple as that. **1-** We don't know what effect the gravitational slingshot would have on Earth's rotation. Earth is currently rotating at 360° per 24 hours. Which gives it a speed of 1675 km/h ([reference](http://www.universetoday.com/26623/how-fast-does-the-earth-rotate/)). Any sudden difference in this would be quite catastrophic and would probably end humanity. **2-** Sunlight is *extremely* important for human (and other mammals') health. "*According to epidemiologist Robyn Lucas at Australian National University, analysis of lifespan versus disease shows that far more lives worldwide could be lost to diseases caused by lack of sunlight than to those caused by too much, and it is inappropriate to recommend total avoidance of sunlight.*" Also: *Multiple sclerosis (MS) is least prevalent in the sunniest regions. Exposure to the ultraviolet-B radiation of sunlight appears to be most important and this may operate via vitamin D synthesis.* ([Wikipedia Article](https://en.wikipedia.org/wiki/Health_effects_of_sunlight_exposure)). And of course don't forget that sunlight is required for the synthesis of the vitally important vitamin D. (Also read [this article](http://articles.mercola.com/sites/articles/archive/2012/09/29/sun-exposure-vitamin-d-production-benefits.aspx) for a quick idea of how essential sunlight is). **3-** Remember chilling winter nights? Well, without the sun it is going to be one unending chilling winter night forever. No math required. And this chilling winter night would grip Earth as a whole. With no sunlight, the temperatures would plummet *quickly*. The mean temperature in deep space is barely higher than absolute zero (-273° C) and a cozy mean 24°C of Earth would drop dramatically in the absence of the sun. This is a chart of ocean depth versus temperature, present on wikipedia. [![enter image description here](https://i.stack.imgur.com/9zJ4k.png)](https://i.stack.imgur.com/9zJ4k.png) Mean ocean depth is 3000 meters and the temperature below 1000 meters is less than 6°C. Furthermore, water is a bad conductor of heath and if moon is shot away from Earth, a layer of ice would quickly form on the tide-less oceans, trapping the heat below from radiating into the environment. And in the presence of a moon (and tides) the motion of top layers of water would quickly radiate away their heat in the chill of deep space. Damned if you do (have a moon) and damned if you don't! **4-** Did I mention that sunlight exposure is vital for children? Children deprived of essential time under sunlight develop short-sightedness. If we survive for 40 years (extremely, extremely improbable), 70% of the next generation people would have severe cases of myopia and rickets. The rest 30% would be frighteningly ghastly and barely able to feed, let alone actively work. **5-** We cannot grow crops in the absence of sunlight. No, not with artificial lighting. First of all, how would we establish hundreds of thousands of miles of fertile, underground farmlands when we ourselves would have barely the liveable space? Secondly, how are we going to provide sufficient lighting to this enormous area? The sun provides Earth with 1,575 x 10$^{18}$ joules per year. This is several times greater than the combined energy consumption of the world and this is how plants get vast amounts of free energy. ([Reference](https://en.wikipedia.org/wiki/Solar_energy)). So no, you cannot hope to grow crops underground in the absence of sun. At all not. # Conclusion No, we cannot survive in the long run (more than a few weeks) without the sun. [Answer] The amount of time humanity would have would largely depend on the velocity of the earth after the slingshot and/or the time it takes for the slingshot to occur. The thing to keep in mind is the sun wasn't snuffed out, the earth is just moving further and further away from it. The sun will still provide light and heat just in lower and lower amounts as the distance the earth travels from its normal orbit increases. Think about how long it takes for a spacecraft to reach say the orbit of Mars from earth orbit. Some of the faster craft would take several months at closest approach, but if you are bearly hitting solar system escape velocity, it would take closer to a year. If you had a slow enough escape velocity you would have time to implement drastic plans to buy you even more time to build colony ships, underground or underwater cities, etc. For example, you could intentionally release as much greenhouse gasses as possible in the atmosphere to offset the cooling for a time by doing drastic things like burning all the forests on the planet (they were going to die anyway) or converting chemical plants into massive greenhouse gas emitters, etc. Also, there is the possibility that the slingshot would take the earth closer to the sun for a time before it passes the sun and continues on to escape the solar system. So you could have the opposite effect where the earth superheats for a while and then dies an icy death. Either way, you should have more than a few weeks if you assume the slingshot was not so powerful it killed all the people on the planet by its self. **Edit** I just noticed that you mentioned decades of warning. I think with decades of warning there would be a much higher chance of humanity surviving. I think you would see a massive global mobilization akin to going into a world war as every nation begins working on massive projects to delay the cooling, create colony ships, and/or go underground with zero regards to environmental contamination. Think world-wide Manhattan project for a minimum of 20years (warning period) with maybe 5 years twilight period (extended time till the surface of the earth is unliveable despite all intervention) with like 90+ percent of the GDP going to collosal extinction prevention projects. [Answer] There's actually [a popsci article about exactly this](https://www.popsci.com/science/article/2013-07/if-sun-went-out-how-long-could-life-earth-survive). Pertinent: > > Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet's core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology. > > > Also pertinent: > > Humans could live in submarines in the deepest and warmest parts of the ocean, but a more attractive option might be nuclear- or geothermal-powered habitats. One good place to camp out: Iceland. The island nation already heats 87 percent of its homes using geothermal energy, and, says astronomy professor Eric Blackman of the University of Rochester, people could continue harnessing volcanic heat for hundreds of years. > > > It would be a miserable existence, but potentially sustainable with sufficient warning. [Answer] If humanity were to survive, there would need to move underground. They would need some sort of power. Some that could last a long time probably some form of nuclear power.You Could probably grow food using artificial sunlight the main problem would who got to live in these underground shelters and who didn't. Overpopulation and Limited resource could also be a problem long turm. But I guess the overall answer to your question is yes. As long as you have a source of power to produce light and heat, and plants growing under artificial sunlight. Then yes it is possible that human life would continue. [Answer] **Could humanity survive?** Yeah, in theory. You probably hit the nail on the head right in your own question. Large nuclear powered closed-loop systems could be built and stocked with fuel and other consumables with present-day technology and enough advance warning. **Would humanity survive?** These types of shelters would take a tremendous amount of input to build, and it is certain that most people would be left out in the cold - literally. Consider the reality of being a person on Earth when this advance warning is given. You are almost certainly not in the select (intelligent/wealthy) group that will be chosen to survive in the shelters. Would you accept dropping everything in your life for the next two decades to contribute to a project that, at its fruition, will literally shut the door in your face? Would you accept a majorly decreased quality of life as the worlds economies crumble due to a large majority of resources being poured into a single project that has nothing to do with market forces? Would all of humanity drop everything in the face of certain death to give a chance to a select few? I would like to think that humanity is capable of selecting the best people and sacrificing the rest of us to give them a chance, but I am not sure when push came to shove that it would work that way. See the "Remembrance of Earth's Past"/"Three Body" trilogy for (one author's) pretty in-depth exploration of this concept. **Say Humanity Survives - Then What?** You are probably right that eventually humanity will have to venture out into the void in search of resources. However, it is still easier to survive on a sunless, frozen Earth with all its resources (nuclear fuel, geothermal energy, water, oxygen) than to survive in deep space. If the goal is to get to a new, more habitable planet that's fine, but humanity would still need to find a target and then live for (many, many) generations on a (massive) spaceship. In addition, the research, experimentation, and industry necessary to develop deep space capabilities would be gargantuan. Depending on how many people can be sheltered and what their resource situation is, this may be too large of an undertaking. **So?** Hope I'm not sounding too pessimistic here. I think the answer to your question is a very slight maybe. I can't immediately rule out the possibility of long-term survival, but I sure wouldn't bet on it. [Answer] Without the sun, humanity has lost. The reason for that is simple: The sun powers everything. Without it, we don't get the heat to keep all those processes working that make Earth be the place it is. First, the atmosphere would probably freeze or just become liquid. Then, when the Earth is in vacuum, the oceans wouldn't help anymore at all. This is because in vacuum, water simply doesn't want to exist in the liquid state - if it doesn't freeze it automatically starts to boil (even at, like, 1 degree Celsius). Then, we wouldn't have anything anymore that could balance the temperature out. Furthermore, we would have to filter the air that we could preserve in underground bunkers or the like and at some point, we would run out of supplies. At this point, the normal folk would be long dead. To conclude this, it would certainly be an interesting topic to write about, if it doesn't bother you that at the end of the book, everyone would be a really cold, frozen ball of frozen meat and blood. You know, frozen. It would certainly involve a lot of cold and death. [Answer] My assumption would be that the timeline for such cosmological events from detection to eventual causation would be in decades or a century. Even the dislodgement and slinging would be a slow process in human scale. At these scales we would be able to bio engineer us out of the situation. We probably won't be the same species. Other questions is would Earth be alone in this journey. Will there be other planets ,gravitationally locked to us. Could then we convert Jupiter into a mini sun like in the space Odyssey book. ]
[Question] [ In [Weapons for a civilisation-destroying giant robot](https://worldbuilding.stackexchange.com/q/36742/75) I asked about what weapons might be placed on a sixty-billion-ton fusion-powered snakebot 9.27 km long and 1.19 km in diameter, armoured with 224 metres of Boron-Carbide surfaced Tungsten-Depleted Uranium alloy armour. This question's predecessor: [Defeating the Snakebot of Doom](https://worldbuilding.stackexchange.com/q/37177/75) was shot down - and rightly so - by March Ho, who pointed out that its ground pressure was such that it'd sink into the bedrock like a rock in jelly. So, now we have attempt 2, revised (by the alien adolescents before launch) to account for ground pressure and some other factors. The Snakebot of Doom is 446 metres in diameter, with a body that is cylindrical for 7480m, and then tapers down to a point over a further 669m, the tail matching with a similarly shaped mouth. Its internals are made from a compound functionally similar to an AZ91D/SiC syntactic foam composite, with density of 0.97 g/cc, or 970 kg/m3. Its armour - which is 14 metres thick - is made from Tungsten-depleted Uranium alloy plates with a surface coating of Boron Carbide, and underlaid by an open energy-absorbing magnesium alloy foam. The Snakebot of Doom weighs 1.486 billion metric tons with an effective density of 1271 kg/m3, has a maximum footprint of 3.34 square kilometres, and a ground pressure when on its belly of 4.3 MPa and when rolling in a hoop, a ground pressure of 13 MPa, on the order of the ground pressure of a woman running in stiletto heels. While these ground pressures are high for a vehicle, this is acceptable, as its purpose is to destroy infrastructure - even below ground - by rolling on it. The snakebot is equipped with a multitude of sensors on its skin, including optical sensors from the far UV to the far IR, electromagnetic sensors, audio sensors (for what it matters given that it would most likely have to stop moving to hear anything) and radiological sensors. It also has broad-band radar and lidar capabilities. While these sensors are surface-mounted, they may be retracted for defensive purposes (and to protect them if the snakebot rolls), and replacements are available further beneath the armour in case of battle damage. The snakebot is armed with 512 "small" railguns firing unguided steel 4.5x72mm flechettes at 5000 m/s, at 24 around rounds per second, 128 or so "medium" railguns dispersed over its outer armour, each firing a steel command-guided and optically-self-guided flechette about 18x288mm long at velocities of around 5000 m/s, at around two rounds per second. It is also armed with six large railguns in its "mouth", only one of which is available for use at any time, the others being retained deeper beneath the mouth's armour as immediate-use backups, firing 144mm diameter, 2304mm long optically-self-guided munitions at a velocity of around 7000 metres per second, at about 40 rounds per minute. These munitions may be single depleted-uranium long-rod penetrators, or they may be capable of breaking up into hundreds of unguided steel sub munitions at some point prior to impact. As a weapon of last resort, the Snakebot of Doom can launch up to sixteen scramjet-propelled ballistic missiles each containing a fusion warhead in the eighty-megaton range, with built-in ECM and anti-anti-missile defences (small command-guided railguns), before having to take around two weeks to build replacements. Resupply of these munitions (except for the depleted uranium and atomic munitions, which would be used sparingly) would be by the expedient of the snakebot "eating" ferrous human infrastructure and processing it into more ammunition. To address a point made that guided munitions would be difficult to fabricate, these are being produced by nanoassemblers, and are not significantly more difficult for them to produce than an unguided projectile. The limiting factor is surface area and nanobot availability. The snakebot is supported by a multitude of nanite-controlled birds which act as its spies. The controlled birds act naturally as far as possible, and each bird stays within its species' natural range. They will not attack and neither will they defend themselves from attack beyond those attacks or defences typically used by their species. However, they are able to observe the preparation of human defences and the Snakebot of Doom is able to act on this intelligence, if necessary by destroying the defended area with its stand-off railguns instead of simply flattening the area. Prior to commencement of the attack, the snakebot's nanites have also tapped into the public internet, however, they cannot rapidly decrypt secure communications, not being equipped with quantum computers (unlike their military nanite brethren, which were not deployed on this mission). Using this information, the Snakebot has been tasked to destroy all human infrastructure significantly more advanced than a shack or a tent, and to defend itself against counter-attack. Its target priority is to attack targets in the most militarily-capable areas first, prioritizing command and control and nuclear stockpiles. It is not interested in exterminating humanity. Individual humans are of little interest to it unless they are counter-attacking with any effectiveness, at which point the snakebot will simply eliminate the threat in the most expeditious manner possible given its options. However, neither will it attempt to preserve the life of humans or any other species. If damaged, the snakebot's controlling nanites will use whatever materials available within the machine's structure and in the environment to effect repairs. The snakebot took around ten years to build beneath the Antarctic ice-cap, and the time to repair damage can be expected to be roughly inversely proportional to the amount of damage - the more damage, the more nanites will be required to repair it, and conversely the slower the repairs will be. Relatively minor damage can be expected to take as little as a few hours, and major damage such as the total loss of one reactor can be expected to take many months to a year or more. When the snakebot has destroyed all modern human infrastructure (i.e. anything more advanced than a shack or a tent), or it is incapacitated to the point where it cannot continue its mission at all without first effecting repairs, the snakebot and all the engineering nanites on earth, including those controlling birds, will self-destruct. Don't worry, the birds won't be significantly harmed by their controlling nanites, either while being controlled or when the nanites controlling them self-destruct. Any nanites captured by humans will self-destruct, of course. **The question:** Given the entire military and civilian resources of the modern world (like we *wouldn't* unite to get rid of this thing) , how can the Snakebot of Doom be defeated, or are we destined to be reduced to living in crude lean-tos and tents until we can rebuild our civilisation? Please remember that we're talking about the modern age. While the Snakebot of Doom has fusion reactors, *We currently don't*. [Answer] Liquid Oxygen. The foamed magnesium inside the snakebot is insanely flammable, so dousing the snakebot with tankerloads of LOX will make any open spark or flame ignite whatever is flammable. Depleted Uranium is also flammable, (indeed, when used as an APDSFS round in a tank it is "pyrophoric", in other words will spontaneously combust under the heat of friction and the presence of oxygen as it passes through the enemy tank). Even dropping large tanks of LOX *near* the snakebot and allowing them to burst open and radically increase the amount of oxygen in the local environment, followed with hard impacts against the outer surface of the snakebot should start raging fires. (Since you have continually upgunned the snakebot I'll respond by having the US Navy shooting at the snakebot with their 64mJ railguns, under the cover of a rain of "Sunburn" mach five anti ship missiles and the usual hailstorm of conventional munitions). If the snakebot is ingesting the oxygen enriched air, then fires shold be induced within the magnesium interior structure as well. [![USS Zumwalt](https://i.stack.imgur.com/HGSeY.jpg)](https://i.stack.imgur.com/HGSeY.jpg) [![Sunburn](https://i.stack.imgur.com/WFpZz.jpg)](https://i.stack.imgur.com/WFpZz.jpg) [![enter image description here](https://i.stack.imgur.com/LTBi0.jpg)](https://i.stack.imgur.com/LTBi0.jpg) Tell the Earth Defense Squadron to bring marshmallows.... [Answer] You might just want to write off one continent, say South America. This is clearly not optimal, but would seem to work pretty well in terms of preserving the rest of the planet. You have not specified just how fast the SOD moves, and even suggested that it will move most quickly when rolling itself along like a giant hoop. Let's take 100 mph as a starting point. You have also suggested that the SOD destroys buildings by rolling over them. This limits its destructive footprint to a track no more than 446 meters wide - call it 1/3 mile. Then it will take about 1200 days, or nearly 3.4 years, to cleanse an area of 1 million square miles. South America has an area of about 7 million square miles, and a worst-case time of about 24 years to scour the entire continent clean. During this time, teams of combat engineers will be building sacrificial structures in the cleared areas, requiring a repeat visit. Done properly, the SOD can be led by the nose, around and around the devastated region, condemned to a never-ending mission of futility. Applying a bit of analysis to determine the SOD's targeting priorities, I suggest that the SOD can actually be confined to a much smaller area, effectively tracing out a repetitive loop. The actual resources required will actually be smaller than you might think, since it's not necessary to produce urban concentrations of structures. A few large, flimsy (that is, cheap) widely-spaced structures will do the job as long as there are no alternatives nearby. And, of course, these sacrificial structures will make excellent testbeds for the latest ideas in booby traps. [Answer] It is worth noting that any “guidance” feature I can immediately think of that would be feasibly mountable in the railgun rounds isn’t going to functionally work, given their collosal momentum in their given direction, and the fact that they are most likely surrounded not by a shroud of air but rather rapidly expanding plasma. --- Feasably, as noted by fgysin ‘s answer, this really just depends on how ‘hax’ the interception accuracy on the railgun batteries are, and whether it can reconfigure where on its body they are located in a pinch (because, all things considered, you only have roughly half of them available at any given angle, since half the snake roughly ground facing and is circular). --- With this in mind, you can decide how effective each of these are (in hindsight, they're all kinda just brute force methods, really, you should combine them with more rigid overall strategies): ## Saturation (least feasible, AKA distract and bash) Plain and simple, shoot enough things that you lower the ammo supply enough that it has to be picky with its targets, also hopefully inflict some minor damage and get it to retract its sensors. Then do some pattern bombardment with ICBMs. Bonus points for trying to disable the smaller rail systems with smaller arms fire to slow down the intercept rate (e.g. .50 cals, Autocannons etc.) Primary con for this one is that any force that large outside of a dedicated air assault would most likely be spotted ahead of time by birds and would then eat a 80 MT warhead. Whoops. ## Blind and Bash Sort of works like the saturation method, except a lot less threatening. In this instance, you pretty much just have your aircraft with powerful radar systems just beam active all over your snake, functionally covering it in radio noise. This approach also involves shelling it with flare shells/munitions all around and covering the thing is smoke with a similar method. Don’t forget heavy audio shrouding and some suicide vehicles just blasting out gamma radiation. Oh yeah, then pattern bombardment with nukes. Bonus points for having some dude playing guitar on the back of a truck with megaphones, and having one of your gamma sources on the truck. Also bonus points for adding a transmitting radio telescope to the mix. Primary con is pretty much the same as the first one. But really, once the snake is blind, you’re mostly good to go to town on it. Actually, just covering it in smoke might be sufficient. Radar doesn’t go too well through it and lidar well, really much either. But the other approach is much cooler. There’s arguably a more efficient way to do this one. ## Just wait until its like, in a 500-600 deep body of water and just go to town with your nuclear arsenal. Seawater works better here. Edit: Dangit, you beat me to it while I was doing the writeup. Well, you do the deep water scenario here, but it could arguably work at shallower distances. See, seawater has the nasty habit of pretty much hard blocking all of your snakes detection systems with only like, 20 m of depth. Has the bonus of making the shockwave potentally a lot more ruinious on your megasnek as well. Oh yeah, also railguns don’t work too well when they’re submerged, for a few reasons (conductive medium between the rails means you can’t build up as much potential charge, and y’know, shooting through water sucks), and rearing its head up out of the water probably ain’t going to give it enough shooty to intercept enough of your warheads. Not that it should really know they’re there. Not saying it’d be impossible to avoid, given our snake has magical bird spies that wouldn’t feasibly be able to communicate with it in this instance anyway (at least, not fast enough to communicate about the ICBM launches). Digging itself deeper might feasibly work if it finds out in time and the terrain permits, probably would work better than the "shoot down the mach 25 icbm warheads with the few railguns it can bring to bear". There’s a kinda obvious con in that well, you just covered a huge swathe of water in a pretty much yet unprecedented amount of nuclear fallout. Snake is possibly dead, but good job pretty much ruining a potentially huge part of our biosphere. Also, giant nuclear tsunamis, huge amount of nuclear fallout into the superstream, earthquakes etc. But they’re kind of shared between all the methods. Snake has also had at-least 20 years to think about this however, so it's probably going to try the smart thing and pretty much cover any distance it travels underwater via the north polar cap, which slows it down, but leaves it near undetectable until it emerges on land, where it's safe. Also, getting all nations to agree to such heavy nuclear bombardment is somewhat questionable. Also applies to all answers. After this, it just comes down to whether the firepower is enough to disable/destroy, and I don't specifically know that. --- ## Other method. While the snake is on its military destroying spree, find and hire a huge number of graphic designers (ideally some of which are the type that are extremely proficient at physically drawing technical documents, just in case snake decides to do some EMPing everywhere, or y’know, power goes out during later phases), give them the tools, and make a codex of advancing human technology (from basic stuff to maybe early digital age computing equipment, including stuff like mining and refinery equipment and whatnot) in physical books form. Books aren’t exactly more complex than a tent, but if the snake calls bullshit, just make it in single pages. Anyway, print off dozens of copies and distribute them across the globe. If you need more time, use the dummy structure/escaping plane/chase the space station method to buy yourself more time. Once the snake kills itself, use your new codices to develop societal equipment and mechanical equipment again at an unprecedented rate, use your extremely high technological base to build your country’s population, and restabilise world order. Bonus points if no one else thought of this and you can come out even better than you were before the snake invaded. Blamo, steam/diesel punk setting where humanity is searching for knowledge documents that hold the key to the digital age they were in only a few generations ago. Really, given that the snake isn’t really just burning everything, all the library resources collected by humanity over the ages would still be there, you’d just need the starting farming equipment so you can self-sufficient enough that society can start searching and expanding its manufacturing and tech base. Okay, that's a little out of the scope of the question there, but it's a reasonable method for coming out on top after snake encounter. --- Also off topic a little, but why not use nanobot spies in ordinary people as well if they can function well in birds. You already can have them in birds, so why not chicken, total global saturation (well not really) of nanobot spies (after they're eaten). [Answer] The biggest hole in the Snakebot's defences is that they are all open-air weapons. If you can catch the thing while it's traversing the deep sea floor, you could use nuclear depth charges and pound it into rubble before it could stick enough of its body up above the surface to defend and counter-attack. Of course, it would only spend a lot of time on the deep sea floor if it was trying to be sneaky, probably on its way from Antarctica to its first target (probably Washington DC to decapitate the US government, unless it reckons that another country is more militarily capable). Once it began its attack, it would likely cross open water via shallow sea routes so that it could more readily defend against an attack at those times. Still, there may be times when it can't do that for whatever reason. It may be possible to force it into bypassing a logical safe sea route by the expedient of mining it or its approaches, forcing it to stand off and traverse the sea by a deeper route. A mistake that a lot of the people posting answers to this question seem to have made is assuming that Big = Dumb. This thing is as smart as a whole army of humans, and it has spies *everywhere*, flapping around being birds and watching everything that birds can see, as well as tapped into the internet and broadcast communications. Whatever you do to defeat it will have to either beat its reaction time, which is pretty good under most circumstances, or be unanticipated by enough of the committee of nanobots that run the snakebot that the rest dismiss the possibility as too unlikely to worry about given its current operational constraints. Also, *it isn't advertising that it has bugged the world's birds*. The birds will behave naturally as far as practical, they might just spend a bit more time looking at humans than they previously did more than ten years ago when the nanobots began to bug them. What humans really pay serious attention to what a bird looks at if the bird doesn't bother them and doesn't act unnaturally? Since the nanites self-destruct harmlessly if a human examines a bird closely enough, it is unlikely that they'll be discovered. Hence, the best chance of destroying the snakebot after it has begun its attack is to force it via nuclear land/sea mines in shallow areas such as the Bering Straits to traverse deep ocean such as the North Pacific, then to depth-charge it, given that it must raise an extremity above water to counter-attack. [Answer] Since the snake points to the military base, all we need to do is: 1. Prepare a bait with some nukes along the path of the snake 2. Move all the ships (and submarines) which had nuclear weapon at the extreme range of its weapon 3. Wait for the snake to be near (or over) the nukes At this point detonate the nukes, than fire the weapon from the ships and finally after 20 minutes fire the weapon from the submarines. Since the first wave of nuke probably will do some damages (after all they are at nearly point blank range), the other two waves probably are sufficient to destroy it or to make so much damages that then you can simply destroy it with conventional weapons. Also, since the snake is probably slow, it probably be vulnerable to kinetic weapons, like the impact of objects (tungsten rods ? Lead/Mercury rods ?) dropped from very high altitude, outside the range of its point defense. Aside the problems noted by Thucydides in his answer, you still have some pretty basic problems. **Where to get all the depleted uranium (and all the other materials) you need ?** Earth as probably some tens of million tons of uranium totally, you are speaking at least of hundreds of million tons. And most of it is extracted (at a rate of about 50.000 tons/year) in country like Canada, USA and Russia and Australia, which I am pretty sure will note that all their uranium disappeared. Given the density of Uranium, if your nanites could match the current production of uranium, you are producing just about 2600 m3/year. Given a 14 meters thickness, also if only half is uranium, you still have that a section of the armor of 1 meter length is about 18990 m3, so you need about 7 years to extract the material to build 1 meter of the snake. And no, you cannot produce it by fusion, since also stellar core stop it's fusion process when it produce iron and the heavier elements are produced by a supernova. **Build it in Antarctica** Antarctica is isolated (not really) and has nothing more that water. So you have at least two more problems: how your nanites will spread and how do you hide that you are building some really big mining factory ? Also, Antarctica, while isolated, is not really abandoned and I have no doubt that such a activity will be hidden for so much time. Basically your snake will probably be destroyed long before it could be operative. **Wrong starting point** From the Antarctica you have three choices as first target: South America, South Africa and Australia, each of them are a good terrain for defense and you need to go swimming to reach everyone of them. Since the only realistic starting point is South America (it is the nearest to Antarctica), the snake has to handle the Andes, which make the snake really vulnerable and the attack simpler: also with all the snake's weapons there are still the mountains to make a shield. Also, how a such massive thing can ascend from the ocean floor once it left Antarctica ? **The snake will run out of ammunition** At this firing rate, you fire about 4\*10^9 kg of ammunition in one minute, and the snake need to replace it rebuilding it. So it must consume the equivalent material every minute or shutdown some (if not most) of its weapon. Not considering the problem to move all the ammunition inside the snake. **It is still too heavy** While 13 MPa can be the max pressure, as I seems to understand just 4.3 MPa can be way too much if "the German WWII Maus tank had a ground pressure of merely 0.14MPa, and it quickly sank into the ground during its field trials" like reported from March Ho in his answer. And while you are in the range of pressure of a woman running in stiletto heels, you must consider the ground: on asphalt it is true that you don't sank, but on a softer ground you sank very fast. And you have the problem to move on ice: it harder than grass ground and somewhat softer that asphalt, but melt under pressure (the basic principle of the ice skates) [Answer] EMP from over the horizon and blind it, The EMP blast from a nuke can extend beyond the horizon ( the snake can't intercept it because the earth is in the way). The EMP might not penetrate the meters of armor, but who cares. It will fry the electronics near the surface, which are all the sensors. The snake will be blind and unable to intercept missiles or spot its opponents to shoot them. Then just nuke/bomb it into oblivion. As an added plus it will fry all the nanobots in the area to stop/ slow the repair process. If you want to be careful do it with three surface skimming nukes. One emp at 80 miles out to take down the nanobot probe birds that might spot the next one. The second at 30 miles to blind the snake and a third to kill it. It is possible to shield electronics from EMP but doing it well requires wrapping them in solid layers of conductors to create a faraday cage. The really hard part is protecting sensors (cameras, missile guidance systems, gps) which have to be on the outside. [Answer] 1) Nuclear land mines. Yes, it's spies will tell them where they are but it has no weapons that can dig them out unless it's just about on top of them--but at that point an observer pushes the button. Knowing where they are they don't pose an actual threat but they can contain it if you emplace a ring of them around it. 2) Now that you have it pinned you call in NASA. Grab a whole bunch of nukes and head for the asteroid belt. You want a very solid asteroid (stony iron or something more metallic if you can find it) probably something around half a mile across although just how big depends on exactly how tough the snake is. Build a base dug into one side of the asteroid, gently lob nukes around to the far side and push the button. Do it right and you can get something like 10% of the bomb's energy into motion--your asteroid will move. Take the asteroid well inside Earth's orbit, approach from as close to the sun as you can. Line up on the snake, the crew will bail at at the point where their rocket can push them 4000 miles before the impact. The snake's spies don't operate in space, such a rock is basically undetectable by modern technology and you didn't specify any super telescopes--the snake won't see the rock until it touches the atmosphere and there won't be anything it can do about it at that point. It's defenses are formidable but they can't stop the huge energy of the rock. The rock I'm using isn't big enough to actually smash the whole snake because a rock of that size would be pretty bad for humanity (It would rival the dinosaur killer.) However, it will cut the snake in two and the parts will be devastated--the snake can be finished off with nukes. [Answer] An approach so different I decided to make it a separate post: Contain the snake with nuclear mines as in my other post. Now, gather the world's supply of artillery. The snake can stop at best 13,000 shells/second (and in practice I don't think it will get 100% accuracy.) The massed artillery of the world can lob more shells than that. Now, conventional artillery isn't going to do a lot to the snake but all we need is to knock back it's defenses. Observation posts can locate the guns, start mixing in nuclear shells. Some will no doubt get picked off but some will get through and each round that gets through takes down a gun. Each gun that you take out makes the rest easier targets. When you manage to clear the defenses from an area you bring in the big booms with the specific objective of carving a hole in the snake. Once you have managed to cut through the armor you aim your nuclear missiles inside the snake. That super-tough armor will contain the blast nicely--it will devastate the snake. While it's unlikely to finish it off it will make it easy to get another through. Given the nannite nature of the snake it's probably impossible to truly kill but you can keep destroying any attempt to rebuild. [Answer] In my opinion this really did not change the situation at all compared to the first questions. The question really is: Is its anti-missile/projectile defense infallible? * Yes, then it's invincible. * No, then it's just a matter of how many missiles/bombs/nukes/rail gun hits/rods of god/... we need to melt through the whatever-many-meters of armor the current version is supposed to have... And trust me we have enough of them stored on the planet (and can probably produce them faster than we can fire them at this thing...). [Answer] Simple; **hack the nanites.** Quote OP: "Prior to commencement of the attack, the snakebot's nanites have also tapped into the public internet, however, they cannot rapidly decrypt secure communications, not being equipped with quantum computers (unlike their military nanite brethren, which were not deployed on this mission). Using this information, the Snakebot has been tasked to destroy all human infrastructure significantly more advanced than a shack or a tent, and to defend itself against counter-attack. Its target priority is to attack targets in the most militarily-capable areas first, prioritizing command and control and nuclear stockpiles." If it can't rapidly decrypt secure communications, that means it can't quickly fend off a hack attempt, and that means it's *possible* to hack it. Granted, it will be difficult; this thing has advanced technology. *However,* the fact that it can interpret Internet code means it can be targeted or otherwise affected by viruses. Since this thing is actively trying to break into and decrypt information in secure channels, its effectively attacking *government software*, and this will be recognized and reacted to As Fast As Possible. It shouldn't take long to connect the dots ("Mr. President! A giant snakebot is rolling toward the White House! Mr. President, our computer experts report a massive cyberattack! We have no idea what-wait, did you say giant snakebot?") and figure out a solution. They don't even need to hack it; we just need two groups of coders, one to block and deter the snakebot's cyberattacks, the other to reconfigure the software so when it does break through, instead of the valuable information it wants, it gets cleverly designed clickbait absolutely *loaded* with malware. In other words, instead of finding water, it'll set off a bomb. The viruses thus "absorbed" into the snakebot should allow the techies to do one or more of the following options: 1. Gain access to the snakebot's software 2. Gain "feedback" from the snakebot, allowing the techies to analyze its destructive capability, discover its mission, and know its location at all times 3. Cause the snakebot to blow itself up, overload its circuitry, or become confused on what its mission is (or how to fulfill it)-basically, alter and/or break the code 4. Change the snakebot's mission If that doesn't work, this thing has nukes; a well-timed shot or well-placed bomb could blow up a Snakebot nuke and by extension, blow up the snakebot. An EMP could work as well, I'm not sure (you didn't account for nukes in the OP). ]
[Question] [ Humans sleep more then nearly any other creature (true sleep, not low-activity like cats and sloths), and are some of the only true sapient species on earth. Many other intelligent, or nearly sapient, species similarly have much higher degrees of sleep. Clearly we find sleep to be useful. Of course, sleep has its downsides. we spend 1/3 of our life in a state where we can not do anything to take care of ourselves. While sleeping were not producing or finding food, nor are we raising young, finding mates, achieving dominance, higher social status, or more territory, or any of the other things that animals need to do for survival of the fittest. Plus were more vulnerable when asleep. Clearly if humans, or other sapience, could achieve our brain power without dedicating so much time to sleep this would be preferable. The question is rather or not we can. Thus the question, **Can a sapient species evolve that does not require sleep, or requires far less sleep?** Lets narrow the question scope some though, since I may ask follow up questions for certain aspects of sleep and don't want to repeat answers. For this questions I'm specifically looking at sleep as related to brain power alone (which probably means mostly REM parts of sleep). Sleep serves uses in physical healing and other functions as well, but there are other approaches to addressing the body maintenance aspect of sleep and I may ask about them in separate question. Feel free to touch on that aspect if relevant, but mostly I want to focus on just the part of sleep mandated by sapience. I'm asking in terms of any species, not just species evolved on earth-like planets, this may include planets without a standard day-night structure. However, lets focus on species that would be at least recognizable to humans, carbon based, human-like sapience, basically not completely alien (yes I said not completely-alien aliens, I'm invoking some poetic license here; they need to be similar enough to earth species for audiences to be able to understand them). I may ask a follow up question on what alternative sleep-like approaches may evolve in place of sleep, if something sleep-like is required, as a follow up question. For now I'm more focused on rather sleep specifically is required, or generally what parts of sleep may be required if not sleep specifically. [Answer] The dolphin is actually a good animal that possesses a lot of intelligence but also sleeps in a very different way. It's called unihemispheric slow-wave sleep. Half of its brain becomes dormant while the other half remains alert. It allows it to react to its surroundings and survive predators, which is something that any animal would need until it develops the ability to build shelter where its predator evasion becomes less important. You could conceive of an animal that's of human intelligence or higher that relied on phenomena like this in order to survive without what we need, which is rapid eye movement sleep. There isn't a high barrier evolution-wise, since it's a feature of the organism which doesn't have a *too* extreme environmental catalyst. The dolphin does it because it consciously breathes. There also isn't a very good reason for the feature to be lost. If the species can continue to procreate and the feature does not prohibit it, it's likely to stay. I'm imagining a human-intelligence-or-higher animal that also consciously breathes. Perhaps it lives in a colder environment where it still needs to have more muscle movement and have more heat. This is in contrast to our slower metabolism, lower body temperature, and restriction of our muscles so we don't act out the dreams we experience in REM. Its biology has to abate the need for rapid eye movement sleep for restorative function like maintenance of its immune system. If that's in conflict then it's likely won't evolve into it. [Answer] There are are several species which engage in [Unihemispheric slow-wave sleep](https://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep) in which the animal lets one hemisphere fall asleep while the other hemisphere monitors the environment and keeps the animal functioning. For example, some birds with high numbers of predators will do this during long migration flights. Sure, they're sleeping in the most technical sense of the word. But I think the fact that *they're freaking flying while they do it* may be good enough =) [Answer] ## Genetic components & environmental pressures define sleep cycle. It is an interesting question, and as a cell biologist, I am convinced that the key point to answer it lies within the genetic component of the circadian rhythm and the "environment" that constraint the night/day cycle. If I may add, sleep do help the body to "take care of ourselves" (even we find it useless and unproductive!) and that brainwaves is maybe not the good answer to your question. ***Dsollen*** in your question you rightly introduce some results/consequence of sleep on evolutionary and social aspects (producing or finding food, raising young, finding mates, achieving dominance, higher social status, or more territory, vulnerability when asleep. nature of source of the sleep), but you must not forget that sleep is a long-evolved process which takes roots billions years ago during cell evolution - which evolution is based on night/day cycle as primary (and most stable) selection pressure. Billions of years after, this result in a fine-regulated circadian clock present within each of our cells. As you probably know, the circadian clock is encoded by genetic factors: the "core" genes working driving this circadian clock are now well known, and the network they define is quite intricate and complex. There is a lot of research going on about this topic, most of them rely on using engineered cells and mutants which possess a rather similar clock than human. The crucial point is that these genes drive the expression of many cell functions and biological processes, including: blood cell activity, immunology, cell migration, dna repair (thus tissue organization/regeneration), etc. I don't know any good scientific that review all of that at once-its in fact many papers-, but you may start with google scholar. In particular, I recommend the publications of Pierre Baldi, a research scientist of UC Irvine university I meet this year in conference in Japan. His research focuses on the molecular aspect of the circadian clock. For example, see this paper <http://www.pnas.org/content/109/14/5541.short> These deep molecular and physiological implications I briefly introduced above apply at various scale within any species, and this will undoubtedly constrain the answer to your question. The putative evolution of shorter sleep in a sapient-like species is possible with specific mutations (as said above it was shown in humans), but evidence to say that there is no counter-effects are in my opinion still lacking, because it these research do not cover all physiological aspects and molecular levels (i.e., these people may have some defect at levels not measured yet, such as immunological resistance or tissue regeneration) Therefore, to shorten the sleep cycle also means increasing the risk of developing cancer and diseases: <http://www.nature.com/nrg/journal/v9/n10/abs/nrg2430.html> but also may change the ability of this species to answer to pathogens and infections: <http://www.pnas.org/content/109/14/5541.short> As it took millions of years for this system to evolve in simple then more complex organisms, with various complexity and scale, I can't conceive that we could suddenly (or over few years) "suppress sleep". Rather than that, I imagine that, in a putative fiction world or close future, that sleep may be "optimized" through appropriate genetic treatments and methods, assuming we got a better knowledge of the molecular processes at work by then. But in a naturally-evolved process, it may well take millions of year to evolve it to a more optimized circadian clock (and assuming the day/night cycle is not changed and still of importance). You may also imagine that in a world where the night/day cycle have very short nights, then you have about 100% chance that single-cells, then multi-cellular species will evolve in response to this environmental condition in their own specific way. Hope my answer is helpful, Best, Arno [Answer] ## Yes, in fact with the line of sapience getting blurred, it may already exist. @The Anathema had some good points on dolphins, but I have some things I'd like to add. Recently [Koko the gorilla](https://en.wikipedia.org/wiki/Koko_(gorilla)) has blurred the line between what we consider sapient and sentient. Despite being a member of a species we count as sentient, she seems to be self-aware. What does this have to do with sleep, you ask? Well if a gorilla can be sapient, then animals we consider to be smarter than gorillas could also be sapient. [Dolphins](https://www.reddit.com/r/LessWrongLounge/comments/3bd83q/are_dolphins_sapient/) are one of the animals we consider extremely intelligent and if they are sapient, then your wish is granted. Now the reason the dolphins sleeps with half its brain at a time can also be applied to an alien. The dolphin sleeps in the way it does because it prevents them from drowning to death. The same reason sleeping fish evolved the swim bladder. If you species is a land animal that evolved to live underwater, similar to whales, then they'd likely have a similar, if not the same, mechanism to survive underwater. [Answer] **If the theory of evolution is accurate, the answer is almost certain to be a genetic mutation.** In fact, [there is mutation](http://www.newyorker.com/science/maria-konnikova/a-gene-makes-you-need-less-sleep) or [for a clinical article](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2884988/) that appears to reduce the normal 8 hour sleep requirement to about 6 hours. The important aspect is that the mutated people suffer no apparent ill effects from what would typically be sleep deprivation and recover more quickly in actual sleep deprivation experiements. As the article notes, who knows what other genetic variation could impact sleep requirements. It is also well-documented that a small percentage of the population (1% or so) are considered to required comparatively sleep - reports of 3-5 hours per night are common in the group, although people do not self report sleep with great accuracy. [Answer] Humans already have the ability to minimize their sleep dramatically: [polyphasic sleep.](https://en.wikipedia.org/wiki/Biphasic_and_polyphasic_sleep) There's a lot of experimentation with taking more frequent sleep breaks, each one for a short time. While there are many critics as to how little sleep one could ultimately require, there are some proponents who claim that it's possible to need only 2 hrs of sleep daily. (One of the most famous people to do this was [Buckminster Fuller](https://en.wikipedia.org/wiki/Buckminster_Fuller), relying on a 30 minute nap every six hours.) When I spoke with a proponent of this approach, he claimed that polyphasic sleep works because a person trains their body to slip right into REM mode, and right out. He personally followed the approach of sleeping for 3 hours in the middle of the night, and then 3 20-minute naps every 6 hours, for a total of 4 hours daily. He had been doing it for 5 years and had no health problems, though he had to adjust his diet to fit his new energy requirements. If this idea already exists in our society today, it should be very plausible to tweak it a bit for your world to make it even less. Perhaps a 15 minute nap every 4 hours, which would only total 1 1/2hrs of sleep daily. ]
[Question] [ I would like to have Earth slowly move away from the sun, taking somewhere between several months and a couple of years to reach the point where human life on the surface is no longer possible. (The story revolves around efforts to get protected in time and the resulting conflicts. So yes, we have some level of spaceflight, but not FTL -- the people who get out will be taking their chances on something like generation ships. Or, as pointed out in the comments, by building shelters on earth to give them longer to come up with a permanent solution.) My problem is that I don't know what could cause this. I can think of ways to knock the earth out of its orbit *quickly* that involve killing most or all of the inhabitants, but I need something that leaves many people alive and gives them time to stew about what's next. I want them to be slowly freezing, not slowly cooking -- moving away from, not falling into, the sun. Is this possible? If so how? It's ok to vaporize a region if that's needed. I'm not fussy about *which* people survive, only that many do. [Answer] You're going to need a lot of energy. As we'll see in a moment, too much energy to do it quickly. Assuming we want to reduce incoming solar energy by roughly 20% (should lower mean global temperatures by roughly 15C), we need to increase the earth-sun distance by 10% (incident solar power drops with the square of distance). That means moving the earth 15 million kilometres further from the sun. The gravitational potential **U** of a body of mass **m** at distance **r** from a mass **M** is given by $U=\frac{-GMm}{r}$. We add a factor of two to account for the kinetic energy: $U=\frac{-GMm}{2r}$ To get the change in potential, $\Delta U=\frac{-GMm}{2.2r}-\frac{-GMm}{2r}=\frac{.1GMm}{2.2r}$ That will need around $2.5\times 10^{32}$ Joules, which is more power than all the world's reserves of fossil ($4\times10^{24} $J) and nuclear ($2\times10^{23}$J) fuel, or around 50 million years worth of solar energy. It also happens to be around equal to the earth's gravitational binding energy. That's the energy you need to remove every part of the earth from every other part and bring them so far from each other that they won't reform. If you apply this energy in an -even slightly - unstructured way (say, by vaporising a continent), you're not going to be worried about the planet cooling down, you're going to be worried about the fact that the floor is made of lava. You could have gravitational interaction with one of the gas giants do it, but it will take a lot longer than you want and you'll need to justify why it's only starting *now*. Probably your best bet is a rogue planet passing through the system and raising earth's aphelion (you can't switch to a new circular orbit with just one interaction, but an elliptical orbit will do fine. Even at perihelion the earth will be colder than now due to thermal inertia). [Answer] Roaming around interstellar space are rogue planets and rogue stars. These are planets and stars that have been thrown out of the star systems where they were formed. I have seen an estimate that says that as much as 50% of the planets formed within a star system are ejected by the time the system matures. If one of these planets or stars swept through our solar system, a number of things could happen. 1. The path of our star (the Sun) could be perturbed. There are many ways in which the Sun's path could be perturbed. Worst case, it could simply be sent careening away from the planets and the planets, no longer having something to orbit would begin travelling in a straight line along their current path. The lights would go out on Earth pretty quickly in this case: days/weeks. A more "mild" case of the Sun's path being perturbed could shift its trajectory in such a way that the Sun slowly begins moving through the orbital disk of the planets. In this case, depending on the speed of the Sun's progression, the planets might slam into the Sun or they might pass very near the Sun and be thrown into highly elliptical orbits. 2. If the rogue element passes through some part of the orbital disk of the planets around the Sun, it could perturb the orbit any planets it passes near. For example, if a very large rogue planet passes behind Mars in its orbit, it could slow Mars down such that Mars' orbit could become elliptical and at its perihelion its orbit could be inside the Earth's orbit. If this were to occur, it's possible that we could use orbital projections to determine that in 3 or 30 or 300 years, the Earth and Mars would collide. 3. If the rogue body passes near Earth, the Earth could be sped up or slowed down in its orbit, in either case causing an elliptical orbit. If the Earth is sped up, it would go through periods of substantial cooling during aphelion when the Earth was farther away from the Sun. If the Earth was slowed down, it would go through periods of substantial heating when at perihelion the Earth was much closer to the Sun. 4. The rogue body could pass inside the Oort cloud way out at the extreme edge of our solar system. The Oort cloud is thought to contain comets and planetesimals left over from the formation of the solar system. Most of the comets, asteroids, and other leftovers from the early solar system have either collided with the Sun, the planets, or have been ejected from our solar system. Thus our current solar system is "relatively" uneventful in terms of heavy collisions. Something passing inside of the Oort cloud could dump a very large amount of that debris into the inner solar system which depending on the amount material dumped could overwhelm our ability to even detect if something were on a collision course with Earth. It would take quite a long time for this material to approach the Earth and we would see a lot of it coming for at least a decade, probably 3-5 decades. And as the material passed by any outer planets on the way in, those planets would fling the material off in various new directions. And some of it would slam into the outer planets and create impacts as we saw with [Shoemaker-Levy and Jupiter](https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9#Impacts). So there would be a lot of new stuff for the Earth to run into for a few 100 or 1000 years. So that would suck... It's possible that we could detect the rogue element approaching our system and predict its effects relatively far in advance. For literary purposes, it could be decades, or we could detect it in the last few years of its approach (in the case of an Oort cloud intersection) leaving us little time to react. [Answer] When you want the orbit of earth around the sun to get higher, earth isn't *falling* out of orbit, it is *raising* out of orbit. To get an object in orbit to a higher orbit, you need to add rotation energy to it. That energy needs to come from somewhere. A massive object passing through the solar system and disturbing orbits (as Kent described) would be an option, but it would not be a continuous development but a rather sudden event. Also, it likely would put earth on an excentric orbit and not a round one like it currently has. Another option would be to leave Earth alone and instead **reduce the mass of the sun**. When the sun would gradually lose mass, its gravity would also be reduced and all planets would go onto higher orbits. However, whatever causes the sun to lose mass would likely also affect its energy output in one way or another. So the main problem for life on Earth would likely not be Earths changing orbit but rather the sun becomming hotter or colder than usual. This leaves the question: *What could cause the sun to suddenly start losing a significant amount of mass?* One possible path how the sun could lose mass would be through a sudden increase of [coronal mass ejections](https://en.wikipedia.org/wiki/Coronal_mass_ejection) (preferably in polar direction so the resulting solar winds don't destroy all life on earth). Truth be told, we don't actually know much about what is going on inside a star. Most of what we believe to know is based on unconfirmed hypotheses. So you can get away with quite a lot of plausible explanations why this is suddenly happening. Another option would be teleportation (when you want to allow it - it's a very soft sci-fi trope). Something or someone teleports large amounts of mass from inside the sun to somewhere else. [Answer] Do you specifically have to move the planet? If not, what's wrong with a good old **giant-asteroid-mass-extinction-event** like the one that did for the dinosaurs? A big comet smashes into the world throws up a load of dust and crud into the atmosphere which prevents the sun's light coming through, temperatures drop, plants stop growing etc. You could even have an giant-asteroid shower of sorts which lasts several years, causing chaos and slowly making things worse as these giant asteroids smash into the planet every few months, destroying a new part (making staying risky even if the dust/temperature drop doesn't kill everyone) and throwing yet more dust into the sky. The other advantage being that there isn't much science to make up or explain. [Answer] I haven't done any calculations on this, but I believe that the Earth and the Moon should be considered one body of mass when calculating its solar orbit. So if the Moon was perhaps vaporized, e.g. with a huge nuclear device, perhaps the loss of mass could be sufficient for the Earth to escape the Sun's gravity. But I have no idea how long would it take? But given you remove 1/7th of the total mass of the system, I reckon it will be relatively quick. Or maybe, if the idea is sound, you could first get the Moon to escape Earths orbit in some way. Whatever amount of energy would be needed to get the Earth to escape the Sun, only 1/6th would be needed to get the Moon to escape the Earth. And if such an event was the collision with a very large stellar body, the collision itself wouldn't itself kill off humanity. This will also give you more freedom in deciding how long a warning time Humanity should have, as you can decide at which rate the Moon should escape from the Earth. **Edit** I realized that this answer must be wrong. If we reduce the mass of the orbiting system, it would of course reduce the centripetal force, but due to the reduced mass of the system, the acceleration toward the Sun would be unchanged (just like two objects with different mass fall with the same speed in vacuum) p.s. Completely unrelated to the actual answer (I don't have enough rep to add comments), Arthur C. Clarke's book [The Songs of Distant Earth](http://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth) is similar to your plot description, i.e. humanity trying to create a future for itself as the Sun is about to go supernova using sub-FTL technology [Answer] If you found a logical reason to reduce the sun's mass by a significant amount, it would lose its gravitational strength and earth would likely slowly orbit outward until escaping or at least obtaining an uninhabitable orbit. ]
[Question] [ I want to do something set in the first weeks of a zombie apocalypse. I am using a viral, slow, infinite energy, 24 hours or so transformation time, zombie model. So I want to know, if a zombie were created, or even 100, could a zombie apocalypse theoretically happen? Wouldn't the military work its way through? I am planning on doing it in a receding/increasing way, so first everything seems safe, and then a zombie is missed on the search and it manages to start again. [Answer] The best way to do this is to make a differential equation and look at the result. Some [people have done this before](http://arxiv.org/pdf/1311.6376v2.pdf) and it really isn't that difficult math. This paper does definitelly leave room for improvement. If you are learning differential equations or want to remember, I highly recommend trying to make a model that works for practice. There is a probability of interaction between a zombie and human proportional to the number of zombies and humans in the close region. For each interaction between a human and zombie, there is a probability of 1 human leaving (Ph for human wins), 1 zombie leaving (Pz for zombie wins), or 2 zombies leaving (Pc for conversion). This is dependant on alot of factors but lets say it is constant. There is the potential for spontaneous birth and death but lets say that is negligible. $$\frac{\partial Z}{\partial t} = CHZ(P\_C-P\_H)$$ $$\frac{\partial H}{\partial t} = CHZ(-P\_Z-P\_C)$$ As the probability for humans is only negative, it means that in short periods of time with any number zombies and humans, non-zero probabilities for conversion, and some interactions: Human will die from zombies. If the value of $P\_C-P\_H$ is negative, however, the number of zombies will decrease too. In most cases, this means that a small group of romero zombies would die out very quickly. In order for a zombie appocalypse to happen, you need some way to manipulate this such that $P\_C>>P\_H$ but not high enough such that all human die too quickly. 28 days later does this by increasing $P\_C$ to high levels with vomiting blood and decreasing $P\_H$ by setting it in largely gunless London. Walking dead does this by making everyone turn into zombies at any death to create a probability of spontaneous zombie / human conversion without invocing the $CHZ$ zombie human interaction parameter. This also effectively bypasses $P\_H$. If you look, i'm sure you can find a good way to do this too. The best way to do this seems to be to innoculate the system. A massive number of zombies upfront will collapse society increasing the chance for victory for the zombies in each interaction (group zombie attacks and sickly underarmed humans). This is best done by adding incubation times, invisible carriers who spread it without other's knowing, or an environmental source which kills most upfront. This means that you can have $P\_H>P\_Z+P\_C$ but have it look like a traditional zombie apocalypse. You also realistically need to include the ability for sections of either group to isolate itself/group up as it increases the ability of the weaker to survive. Some implementation of birth/natural death/ human-human killings would improve it as well. I would also find it fun to include a cyclic "night time" in which zombies have the upperhand while humans do in the daytime. [Answer] Unfortunately, zombie apocalypse scenarios run into a big problem with zombie propagation. Kaine already gave the simple version of the equations but note that there's a big problem here: Either the number of zombies goes up--and the humans are soon wiped out, or the number of zombies goes down--and the zombies are soon wiped out. In neither case do you end up with a zombie apocalypse scenario. Besides, the equations assume humans were stamped out by a cookie cutter. To end up with an apocalypse scenario you need to look at humans in a more complex fashion: You have your average city dweller. Few have much combat capability, Ph will be low, Pc will be high. The zombie "virus" will spread through them like wildfire unless the infection cycle is too slow. For zombies like we saw in the World War Z movie you'll get near total conversion very quickly. You have some combat-capable city dwellers. Unless they are lucky to realize what's up in time and find someplace zombie-proof to hole up they aren't going to fare better but they'll thin the herd a bit before going down. While their Ph is high they will face so many encounters the numbers will get them in the end. Finally, you have the country dwellers. The population density is much lower which means prepared individuals won't have nearly the threat of being swarmed and both firearms and the skill to use them are much more widespread. The lower population density also means more time for a warning. Ph is high and they won't be swarmed. This latter group is the only path I see to an apocalypse scenario. Much of the world becomes fully converted, the survivors are mostly farmers and ranchers. There is also the approach used in John Ringo's zombie novels--the zombie virus piggy-backs on a flu virus. (Some lunatic's genetic engineering.) The flu spreads like flu always does (especially when the lunatic places dispensers in places like airports), the disease is pandemic before anyone realizes it's more than just a nasty strain of flu. With so many infected at the start society collapses before the government gets it's act together. Since his zombies aren't actually undead they don't meet the parameters you set out, though. [Answer] Well with zombies you would need to shoot or hit them directly in their brain. Since they are undead creatures we can safely guess that a wound, even loss of limb wouldn’t stop them, they also wouldn’t burn easily. So for even a single zombie to go down, it would need to take a hit to the head. Granted they also wouldn’t recover from wounds but that’s it. [Answer] # Zombies are stupid Zombies are by nature extremely dumb creatures. Given time, folks will work out fairly reliable ways to herd zombies with noisemakers and spotlights (or, for style, disco balls). If this reminds you of the (as it turns out made up) story about lemmings, that was my point. If significant parts of the world are relatively unaffected for long enough to develop a real plan, their militaries will be able to muster the resources to clear areas by (for example) having helicopters fly over an area with loudspeakers blaring, dangling live bait (cows, probably) which will build an enormous swarm following it right where you want it to go. When you've got the horde where you want it, just drop the bait, have the chopper speed up and leave - then shell the area, have snipers mop up remnants. Lather, rinse, repeat. # People in zombie fiction are also stupid They never take any realistic steps that could staunch the bleeding. [Layered defenses](https://worldbuilding.stackexchange.com/questions/175265/what-should-i-consider-when-making-walls-or-fortifications-that-can-stand-agains/175272#175272) for the win. I won't belabor the points from that answer too much, but in general - the answer is no. There would not be a zombie apocalypse. The death toll would be almost unimaginable, but compartmentalization, travel lockdowns, and cleanup operations would be enough to keep everyone from dying. # A new world, compartmentalized Zombies would probably never go away. Cities would have to be designed to account for zombie attacks. The goal is to prevent throngs of zombies from being able to overrun them by compartmentalizing damage. Roads would be closable in ways that block all traffic. Where possible buildings would contain few entrances at ground level, instead relying mostly on retractable staircases leading to the second floor. Major arteries (such as today's expressways) would be at a lower level than the rest of the city, so they could be sealed off should it become necessary. # Damage would be catastrophic but not apocalyptic Modern society relies on mass production machinery and the ability to move things around the world in days. Getting enough food into (say) Chicago without roads being clear would become a major challenge very quickly, because the supply chain would be depleted fairly rapidly. And making new computers and cars and power tools would likewise be very hard. Modern assembly lines have precision tools that are used to make all this stuff. Without those tools, and the knowhow to make them, the ability to make complex machinery with interchangeable parts goes away. Much of these capabilities reside in major metropolitan areas, the most likely to fall. But even if every major city fell, enough would still be left that people would be able to restart civilization. Tech might be set back quite far, but enough would remain usable for long enough to prevent people from forgetting how stuff used to work. And people will have (for instance) archival copies of Wikipedia. It is likely that tech levels would, in time, recover - significantly faster than we developed said tech originally. ]
[Question] [ **Some background** As most of us know, accelerating to relativistic speeds requires truly astronomical amounts of energy. I have internalized that a ship carrying enough energy/fuel to accelerate to near-lightspeed by its nature also carries enough energy to destroy a planet several times over, even ignoring the fact that the near-C ship could just ram a planet to explode it rather effectively. The trick, though, is carrying enough stored energy onboard the ship to accelerate to those preposterous speeds, and then decelerate again at some point. Fuel has mass, and mass requires more fuel to accelerate it at the same rate as less mass, and so there is no way, in my understanding, to store enough energy aboard a ship to reach speeds like 0.5C, let alone 0.99C as is popular in these types of discussions. The answer to this problem is to not store the energy on the ship at all, but to beam it into the ship remotely. This is called beam propulsion, and is stupidly easy if you have something like a Dyson Sphere. I'm sure many of you are already familiar with this, but for those who are not, basically, a ship is built with large sail-like structures (think solar sails) that are targeted and fired on by intense and focused beams of energy that have access to astronomical amounts of energy, pushing the ship at a constant and high rate of acceleration for prolonged periods. **In-universe context; and main question** In the sci-fi universe I am building, Dyson Spheres, or stellar engines or whatever you want to call them, are common, albeit very expensive installations, and human civilization overall is very adept at beam propulsion, aided in no small part by their prodigious energy budget. Ships are sent between star systems at speeds often exceeding half of lightspeed (0.5C), and ***civilized space is formed into a network of these beam-powered routes that many of you might know as a concept called an Interstellar Laser Highway system***. This works fine for traveling between systems with established infrastructure to speed you up at one end and then slow you down again at the other, ***but what about traveling to uninhabited systems where no infrastructure has been built yet?*** **Technologies and limitations** In the setting, I have decided that energy can be stored as photons within chambers lined completely with a perfectly reflective substance, trapping photons indefinitely. This method of power storage would be extremely energy dense, and I have read that light confined in this way, at a certain point of energy density, will start behaving something like a gas, and exert pressure, establishing an upper limit to how much energy can be stored in these chambers. So, say we have a starship en route to an uninhabited system. It was propelled to about 0.5C by a stellar laser back in a nearby frontier system, and has been traveling for a few centuries now. I have been trying to figure out a way for this ship to decelerate at its destination, and have tried to avoid having it use the energy it has stored onboard, for fear that it will not be anywhere near enough, but I can think of no other way that does not involve magic or cartoon physics. **The question, expounded** This question has multiple facets: 1. Exactly how much energy is needed to decelerate a ship from (or for that matter accelerate it to) 0.5C ? I am badly under-informed in all kinds of mathematics, and energy is among my weakest areas in math, so I hope someone smarter than me will see the way. 2. Exactly how much energy could be stored in one of those photon-imprisonment chambers of a given internal volume, according to current understanding, ignoring the issue of how to get the photons in and out of the chamber? Would the energy stored in one of these chambers of a reasonable size be enough to decelerate a craft from 0.5C? 3. I've heard that photons have mass, and so would the mass of the light trapped aboard the ship amount to anything that could alter the ship's delta-V? I am also assuming in this setting that they have futuristic engines that can essentially convert electrical energy directly into velocity, among the setting's only clarketechs. Would the photon-imprisonment chambers be superior propulsion to the magical momentum drives if you broke them open? If so, what level of acceleration could they provide? 4. What sources or courses can I consult to try to learn how to work out these math problems for myself? where should I go to actually understand things like the standard Rocket Equation or Specific Impulse? [Answer] **Your photon cage already gives you the most efficient thruster possible: a [photon rocket](https://en.wikipedia.org/wiki/Photon_rocket).** Photons carry momentum (that's how lightsails work) so you simply open a hole in the photon cage and the outflow of photons creates thrust in the opposite direction. Specific efficiency depends on the mass of your photon cages and energy of the photons stored but if you want to do the math, see <https://en.wikipedia.org/wiki/Nuclear_photonic_rocket> for an explanation. The article cites a theoretical max efficiency of 300 megawatts per newton of thrust, which sounds like a lot of energy to store in day to day terms but possessing a means of directly storing photons (effectively 100% efficiency in photon generation relative to fuel stored) is maximally efficient compared to converting fuel to photons as in the nuclear photonic rocket or even an anti-matter powered equivalent. [EDIT] So, here's some basic math to help you get started on your calculations. * Energy to get up to 0.5c. That isn't near a relativistic speed so we should be able to use the classical formula to calculate the kinetic energy: K.E.=0.5\*mv². Plugging in the numbers says that for every metric ton of mass (1000 kg) in the ship requires ~11,234,439,734,210 megajoules of energy to accelerate it to 0.5c. Each megajoule is about equivalent to 1 stick of TNT so, in total, that's the energy of about 2685 megatons of TNT. Or, to incorporate quarage's suggestion from a comment, a megawatt is one megajoule per second so for a normal 500 MW nuclear power plant, that's 712.5 years of output (or equivalently the output of 712.5 500 MW power plants for one year). If the ship weighs a million metric tons, multiply the above number by one million. Also remember that that much is needed again to decelerate the ship back to a stop at the end of the journey. * How much does that much energy weigh when you put it into a photon cage? Well, we know that mass and energy are equivalent through Einstein's famous equation, E=mc². Rearranging that, we get m=E/c². If we plug in the above number, we get almost exactly 125 kilograms, which is amazingly small for the energies involved. So, for each metric ton of mass in the ship, at least 125 kilograms of it has to be stored photons to either fully decelerate it (or fully accelerate it) to 0.5c, assuming perfect conversion of energy to thrust. (For convenience, we ignore the fact that the ship gets lighter as the photons are expended for thrust.) And remember, this is close maximally efficient in terms of fuel to mass ratio for a photon rocket since it's already in the form of raw photons. We don't know how much photon cages weigh per megajoule held so we cannot say any further how efficient the overall system is relative to anything else. [Answer] If there's no laser at the target you have decelerate on your launch beam. This can be done if you can manipulate things precisely enough--when it's time to stop you cut a ring off your sail, it goes on ahead and you flip your spacecraft. Note that the discarded ring must be the majority of the mass of your spacecraft as well as the majority of your sail! Some of the incoming energy hits the sail you have left and pushes you, but the majority goes on by, hits the ring and is bounced back into your sail. You must decelerate fast enough that you're slowed to insystem velocity before the ring gets too far away. Also, given that you are describing a system with many inhabited systems you could decelerate on beams from other stars that are able to bear on your sail. Better get the coordination right! [Answer] ## Use the laser highway system to both accelerate and decelerate your spacecraft [![lightsail config](https://i.stack.imgur.com/jAJUh.jpg)](https://i.stack.imgur.com/jAJUh.jpg) The yellow arrows represent the laser light coming from the origin star system (the one with the laser infrastructure). The red arrows represent the laser light bounced back off the blue detached light sail, onto the pink light sail attached aft of your spacecraft. The pink sail receives light from both behind and in front, however, the blue sail is focusing more light down onto the pink sail's front, so the net effect is deceleration. The blue sail, after detaching, will continue accelerating out into space. No way you're getting that back. [Answer] For something perhaps less reliant on undiscovered physics than a photon chamber, try the [Bussard Ramjet](https://en.wikipedia.org/wiki/Bussard_ramjet): you generate a miles-wide magnetic field ahead of the ship that funnels and compresses interstellar hydrogen into your spacecraft. Due to the speed at which the hydrogen is compressed, it undergoes nuclear fusion, propelling the spacecraft forward. To decelerate you can use the magnetic field as a [magnetic sail](https://en.wikipedia.org/wiki/Magnetic_sail), and shape it so that it no longer causes fusion. [Answer] **You don't have to have a photon cage at all.** > > So, say we have a starship en route to an uninhabited system. It was propelled to about 0.5C by a stellar laser back in a nearby frontier system, and has been traveling for a few centuries now. I have been trying to figure out a way for this ship to decelerate at its destination, and have tried to avoid having it use the energy it has stored onboard, for fear that it will not be anywhere near enough, but I can think of no other way that does not involve magic or cartoon physics. > > > Because the question about the photon cage's efficiency is motivated by this, I'm going to contest the premise entirely and open up the possibilities a little. Good news: someone did already think of one. It was called [Valkyrie](http://www.projectrho.com/public_html/rocket/slowerlight3.php#id--Go_Fast--Nearlight_Starships--Valkyrie_Antimatter_Starship), and it centered on an **antimatter beam-core rocket**. This kind of rocket carries big tanks of hydrogen and antihydrogen, and annihilates them to produce charged pions (and a lot of waste as neutrinos and gamma radiation). These pions are then ejected backwards; their change in momentum is opposite that of the ship, so the whole thing accelerates. While the acceleration is very low, you'll have years and years to slow down and eventually enter a parking orbit around your target star. The biggest drawback of this design is that antimatter is expensive, but a civilization with multiple Dyson swarms for power should be able to create enough of it fairly readily through pair production. There are undoubtedly also engineering problems, such as how antimatter waste products will gradually transmute surrounding material. However, a one-way acceleration of 0.5*c* is tame compared to what Valkyrie or the [multi-stage Frisbee](http://www.projectrho.com/public_html/rocket/slowerlight3.php#frisbee) designs propose for this kind of antimatter propulsion. It also violates no laws of physics, as your proposed electricity-to-velocity drive would, and requires no photon-trapping chamber at all. [Answer] in the science fiction book "The Mote in God's Eye" aliens used a laser to accelerate, then when they reached their target system, built up an electric charge on the hull of their ship. This caused the ship to precess around the galaxy's magnetic field. When the ship velocity had rotated by 180 degrees the aliens then fired another laser pulse to stop the speed all-together. [Answer] You send a decelerator up ahead. The energy you have stored is probably not enough to slow down the entire ship. So you have modules that you shoot up ahead that slow down and begin shooting you with those same lasers that brought you up to speed in the first place. Then you have that decelerator make more lasers and eventually you have set up a new branch of the laser highway on the go. This does mean you will need the ship to be specialised to include these decelerators. But you could also just have a highway building ship be sent up ahead of the main passenger ship. [Answer] ## Just make the light bend back on itself. Did I drink from the wrong bottle? Maybe I woke up in the wrong universe? Or did *Science* print that somebody *re*-solved Maxwell's equations, yeah, *those* Maxwell's equations, and show that you can send out a beam of light that bends around 180 degrees in free space? I don't know, [you be the judge](https://www.sciencemag.org/news/2012/04/light-bends-itself)! ]
[Question] [ In response to [a question about an asteroid filled with degenerate matter](https://worldbuilding.stackexchange.com/q/117195/627), [Ender Look suggested](https://worldbuilding.stackexchange.com/a/117210/627) that using matter from a black dwarf would be better than using matter from a white dwarf since black dwarfs are cooler. A typical white dwarf's temperature might be $\sim$10,000 K, which is way too high. The problem is, it takes a long time to form a black dwarf. The distinction between a white dwarf and a black dwarf is somewhat arbitrary, partly because "black dwarf" is not a technical term. [Some simply say that black dwarfs are white dwarfs that have cooled to the point where they no longer emit a substantial amount of visible light](https://astronomy.stackexchange.com/a/23256/2153). According to that definition, we may already have some black dwarfs (e.g. the companion star to PSR J2222-0137). However, this corresponds to a temperature of about 2800 to 3000 K, which is still too high for the purposes of the original question about degenerate matter. Therefore, I need to define a black dwarf as a white dwarf that has cooled to about 1000 K or lower. The problem is, this is going to take a really long time, and there may not be any black dwarfs this cool in the galaxy. This means that I'm willing to use artificial means to turn a regular white dwarf ($T\sim$10,000 K) into a black dwarf ($T\sim$1000 K). The civilization doing the transformation ranks as [a Type II civilization on the Kardashev scale](https://en.wikipedia.org/wiki/Kardashev_scale#Type_II_civilization_methods) and has all the powers and technologies you would expect them to have (key exception: no FTL travel). How can this Type II civilization turn a white dwarf into a black dwarf, within a reasonable timeframe (say, 100 to 1000 years)? Other specifications: * We'll assume a mass of about 0.25 solar masses, and a radius of about 0.0038 solar radii (radius derived from a [mass-radius relation](http://burro.case.edu/Academics/Astr221/LifeCycle/WDmassrad.html), with Sirius B as a reference). * The white dwarf in question is alone, with no binary companion or planets. * There might be a handy interstellar cloud of gas in the region if needed. * Large-scale mass removal or addition is likely undesirable. * The object shouldn't merely appear black, so you can't paint it black, as it were. --- I should add that [What could be done to make a red dwarf become a blue dwarf, then a white dwarf and then finally a black dwarf in a short amount of time?](https://worldbuilding.stackexchange.com/q/98571/627) does talk about this, but it seems like they're using a black dwarf that's extremely cool (more like 10 or 100 K). There are also some other differences: * Their civilization is a Type III civilization; I have a puny Type II one. * They're fine with FTL travel; I am certainly not. * They want to start with a red dwarf, meaning they have more control over the object. I'm starting from just a white dwarf. * I'm looking for a bit of a hotter black dwarf than they are, it seems. [Answer] Basically, you're asking how to suck the heat out of a while dwarf without sucking all the mass out. That's really hard. The classic three methods of heat transport are radiation, convection, and conduction. A white dwarf already emits essentially all of the radiation it can from its surface, so there's not much more you can do with radiation, other than waiting a hundred billion years or so. Convection carries away heat by the movement of hot matter. That would work, but if you don't return the matter you wind up with nothing left of the star. If you *do* return the matter, you then need some enormous source of energy to lift the hot matter from the star, let it radiate its heat away, and then lower it back without it turning the (huge) gravitational potential energy it has away from the WD into heat and re-heating the WD. Conduction doesn't appear to be relevant since the WD is far hotter than any solid matter. Given near-magical technology, the one thing I can think of is somehow *stirring* the interior of the WD to bring the vastly hotter material inside to the surface where the good old Stefan-Boltzman T4 dependence would radiate heat away much more quickly. It's still a long, slow process, but much quicker than just sitting there watching the WD cool on its own. Note that this stirring should be done *very* carefully so as to not mix too much unfused material into the hotter regions and cause re-ignition or even a nova. See [this article](http://www.daviddarling.info/encyclopedia/W/whitedwarf.html) for some information on WD structures. Some WDs might be stable against stirring; others will go bang or re-ignite. Any technology beyond that looks like entirely magical technology and, of course, with that, you can do anything. Note: The material from a black dwarf would indeed be very, very dense, but it would not be stable. In the star, its stability is maintained by the immense pressure from the star's immense gravity. Once a sample is lifted out of the star's center (the surface of a WD or a black dwarf is ordinary matter because there's not enough pressure there to make it degenerate) it would explode quite violently. [Answer] # Disassembling and reassembling the star The surface of a star is where all the energy gets out by radiation. In a regular sphere that is $4 \pi r²$, but it's volume $\frac{4}{3} \pi r³$ implying a surface-volume-ratio of $\frac{3}{r}$. With $r=0.0038 R\_{solar} = 2643.66 km$ you'd have a ratio of $1.13479 \times 10^{-6} \frac{m²}{m³}$. If you were to change the shape or "split" the star into smaller objects you'd improve that ratio significantly in favor of surface area and thus radiation output. ### Type II Civilisation [Wikipedia](https://en.wikipedia.org/wiki/Kardashev_scale#Type_II_civilization_methods) states about Type II Civilisations: > > Star lifting is a process where an advanced civilization could remove a substantial portion of a star's matter in a controlled manner for other uses. > > > Why not disassemble the star into smaller parts of which each has a significantly stronger energy output per volume? Assuming a civilization that can "remove substantial portions of a star's matter" to repurpose it could also stabilize the removed portions, this should work decently to cool it (at least a lot quicker than it would cool on its own). They might even cool the smaller portions with some additional process. The only thing you'd need after that is the reassembling of all the gathered star matter, but I do not see this being an issue for a civilization that can take a star apart and repurpose the smaller fractions. Basically, you'd just need to put it together - and since it is not an IKEA wardrobe the order in which you put it together does not matter either. --- Please note: I am not an astronomer, just a very physics-interested engineer. I am not certain about what would happen if you were to split a star beside the obvious. [Answer] With lasers. I am serious. [Laser cooling](https://en.wikipedia.org/wiki/Laser_cooling) is a thing. And it works best on gas, which is nice in this context. Now, it might take too long, and too many lasers, to get what you want if you just shoot at the star. You may wish to bring in another star, much heavier than your mark. It will start stealing matter from the smaller one, like this: [![It's a start-eat-star world out there](https://i.stack.imgur.com/LhkJd.jpg)](https://i.stack.imgur.com/LhkJd.jpg) [Source for image](http://www.dailymail.co.uk/sciencetech/article-3597266/The-CANNIBAL-white-dwarf-Rampaging-remnant-star-like-sun-seen-devouring-90-cent-neighbour.html) Shoot your cooling lasers at the matter being transfered between the stars to cool it down. Then collect it before it falls into the heavier star. Store it somewhere else. If you stick to the goal of the linked question, which is to have pieces of star and not a whole one, you may process the matter you are getting from this process into asteroid sized packets. Being a Kardashev II civilization, your people may even harvest some energy from the heavier star to power the lasers and whatever collecting machinery is involved in the process. [Answer] **Turn heat energy into matter via iron fusion.** 1: Start with a specific type of white dwarf amenable to this maneuver: <https://en.wikipedia.org/wiki/White_dwarf#Type_Iax_supernovae> > > Type Iax supernova, that involve helium accretion by a white dwarf, > have been proposed to be a channel for transformation of this type of > stellar remnant. In this scenario, the carbon detonation produced in a > Type Ia supernova is too weak to destroy the white dwarf, expelling > just a small part of its mass as ejecta, but produces an asymmetric > explosion that kicks the star, often known as a *zombie star*, to high > speeds of a hypervelocity star. The matter processed in the failed > detonation is re-accreted by the white dwarf with the heaviest > elements such as iron falling to its core where it accumulates. These > iron-core white dwarfs would be smaller than the carbon-oxygen kind of > similar mass and would cool and crystallize faster than those. > > > The zombie star is good for this application anyway because it cools faster. And we will use that iron core to cool it extra fast with 2: **Iron fusion.** <https://en.wikipedia.org/wiki/Iron_peak> > > For elements lighter than iron on the periodic table, nuclear fusion > releases energy while fission consumes it. For iron, and for all of > the heavier elements, nuclear fusion consumes energy, but nuclear > fission releases it. Chemical elements up to the iron peak are > produced in ordinary stellar nucleosynthesis. Heavier elements are > produced only during supernova nucleosynthesis. This is why we have > more iron peak elements than in its neighbourhood. > > > The fusion of iron is endothermic and so energetically unfavorable. If there is a boatload of energy available it might push it in that direction. Under any energy conditions, fusion of iron (and heavier elements) would consume (heat) energy from the surroundings which would go towards the creation of new matter. Like other endothermically unfavorable reactions, a catalyst would help move this along. We will use **3: Muon catalyzed fusion.** <https://en.wikipedia.org/wiki/Muon-catalyzed_fusion> > > Muon-catalyzed fusion (μCF) is a process allowing nuclear fusion to > take place at temperatures significantly lower than the temperatures > required for thermonuclear fusion, even at room temperature or lower. > It is one of the few known ways of catalyzing nuclear fusion. > > > Fortunately your Type 2 civilization is master of the muon, and they routinely use muon catalyzed fusion to meet all energy needs. But here we turn those persuasive muons on recalcitrant iron, persuading the partners to meet and merge. A tight beam of muons penetrating the oxygen / carbon outer layer might work, or perhaps the muons will need to be generated in situ (if we can find machinery robust enough to withstand the pressure). Additional spatial dimensions could help with this if available but probably that would be downvoted as pure fantasy. [Answer] **Compression. Then expansion. Via artificial gravity.** When matter is squeezed down to occupy less space, it heats up. Conversely if it is expanded, it cools down. <https://physics.stackexchange.com/questions/17948/why-does-a-gas-get-hot-when-suddenly-compressed-what-is-happening-at-the-molecu> If this civilization can simulate gravity, perhaps they have ways of curving space - simulating the effect of mass on space (to produce gravity) without having to use the mass. Exactly how the civilization accomplishes this is left as an exercise for the reader. So: curve the space within the black dwarf more strongly, effectively increasing its gravity. As it is pulled inward, it will heat up. Be careful! If you compress it too much you will get it to the point where it can fuse its oxygen and carbon, and that will make a bunch of new unwanted heat! Stop short of that. Squeeze it to a cozy blackbody glow and let it get back to rapidly radiating heat out into space like it did in its white dwarf days. Then turn off the juice and let space relax. As it expands, the black dwarf will cool. You might still need oven mitts. ]
[Question] [ In the movie *Oblivion*, the Moon has been destroyed by invading aliens. Several shots of the moon show what is left: [![enter image description here](https://i.stack.imgur.com/ncAml.jpg)](https://i.stack.imgur.com/ncAml.jpg) If the moon was somehow shattered like this, what would the effect be on Earth? [Answer] # It Depends **Case 1 - The earth gains a ring.** This case arises when the debris will stay in orbit but not be pulled in by the gravity of the remaining moon. Every night is a little brighter. As the ring gets more evenly distributed, tides would become less severe and eventually die out. Check out this [huffington post article](http://www.huffingtonpost.com/visualnewscom/hypothetical-pics-if-eart_b_3460703.html) about "if the Earth had rings." Some rings may also help with navigation, making finding north trivial. **Case 2 - The moon's (or its debris') orbit decays.** In which case, the moon (or its debris) will slam ([or return?](https://en.wikipedia.org/wiki/History_of_Earth#Formation_of_the_Moon)) into the Earth. Any significant portion of the moon that makes it to earth makes the astroid which killed the dinosaurs look like a bug hitting a car's windshield. The moon or its debris kills almost all surface life. Also, global cooling would occur from the dirt kicked up by the impact(s), not that most creatures would be around to complain about it. **Case 3 - The moon is only temporarily disassembled.** If the debris from the shattered moon is still mostly under the gravitational effect of the moon, it'll fall back down and re-form the moon! This may take a while, since the gravity of the moon is weak. The new moon would, most likely, not look like the current one. In the meantime, the tides and most life continues on earth almost like it never happened. **Case 4 - The moon has gained some energy so it can get out of its orbit.** This event looks like it was really, really big. Maybe it gave the moon (or big enough chunks of it) enough energy to get out of orbit with the earth. In which case, the moon will appear (from Earth) to shrink into the sky, until it is gone entirely. Tides would subside. Animals and plants would need to adapt to the new, moon-less world. Over a larger timescale you'd also see a significant increase in the variability of the tilt of earth's rotation, making seasons less predictable and generally making life much tougher - one discussion is [this](http://www.astrobio.net/news-exclusive/the-odds-for-life-on-a-moonless-earth/) article. [Answer] We'd be screwed. The Earth relies on the moon to stabilise its orbit. A stable orbit is necessary for stable seasons, and its likely that complex multi-celled life could never have evolved without these. You'd be looking at apocalyptically random weather, and depending on the extent to which the moon was damaged, the potential destruction of all life on earth larger than bacteria. ]
[Question] [ **Can humans live on an Earth-like planet where the only difference is that the surface is ~50% water, instead of the ~75% of now?** That is, paleolithic humans... And the new land area hosts the same ratio of biomes that currently exist on Earth, or whatever it needs to produce a human-livable climate. [Answer] Water works as a temperature barrier, especially in the formation and melting of ice. Its also heavily responsible for the redistribution of energy on the planet. So, compared to our planet, your planet won't be as insulated from warming and cooling trends, and things like a global cooling event (volcano, nuclear winter from asteroid impact etc...) will have an exaggerated effect. Global warming events will also require less time to warm your globe as well. Less water might make it difficult for thermohaline circulation (great oceanic heat conveyor belt). If this fails to start, then energy isn't able to redistribute around your globe. This leaves your equator overtly hot and polar regions frozen over. The extremes might make it a bit more difficult, but there is no reason why humans couldn't come about. [Answer] I think this is a "yes, but..." answer. First off, less water in the oceans means less water in the hydrological cycle. So less rainfall. Earth at the height of the ice age is a good model for this: with lots of water locked up as ice, the climate became drier. Deserts expanded, rainforests contracted. [Here's a map](http://www.esd.ornl.gov/projects/qen/nerc.html) of how small the rainforests and how large the deserts were at the glacial maximum. So your planet will be like an ice-age Earth on steroids! Except without the massive ice caps. If it actually HAS an ice age, it will get drier still. How hospitable it will be for humans (or any big land animals) will depend on how your continents are arranged. If you have a third less water than Earth, then [supercontinents](https://en.wikipedia.org/wiki/Supercontinent) are going to be a lot more common during your planet's history. The centre of a supercontinent is very arid and uninhabitable by pretty much everything other than microbes. Basically it is such a long distance from the sea (where water gets into the atmosphere) that any clouds have dumped their rain and ceased to exist long before they reach the centre of the continent. Think of the driest deserts on Earth (hot or cold) - those are positively dripping with water compared to the centre of a supercontinent. Bits of the supercontinent are subject to a [mega-monsoon](https://en.wikipedia.org/wiki/Pangean_megamonsoon) climate, so the biomes there will be unlike anything currently on Earth. All this mega-monsoon data is for Earth at a time it had no ice caps. I've no idea how polar ice sheets would affect this mega-monsoon wind pattern. Here's a paper on [the mega-monsoon through geological time.](http://www.jstor.org/stable/30081148?seq=1#page_scan_tab_contents) This article suggests that reptiles and proto-mammals may have lived in [separate parts of Pangea](https://www.sciencedaily.com/releases/2011/05/110512150823.htm) because of the weird climate. So again, biomes would be very different from Earth today. So your humans could live there, but they - and much of the rest of life - will be constrained to the habitable areas. Ironically your planet has **more** landmass than Earth, but it very likely has **less habitable land area** than Earth. [Answer] Yes. Your Earth-like planet would have a lot more land that is like [Sub-Saharan Africa](https://en.wikipedia.org/wiki/Sub-Saharan_Africa). Existence would be difficult, but it'd be more than possible. ]
[Question] [ So, I'd love to have werewolves in the world I'm building, but as it's a sci-fi setting I don't really want them to be magical. I can stomach *some* pseudoscience, but I want the process to be as realistic as possible. To this end, I've removed the influence of the moon (it's just a cyclic transformation, happens based on an internal clock), silver bullets and holy water don't have any special potency, and I'd be willing to extend the transformation from man to werewolf to an entire day, or even a week if necessary. What I'd like to know now is what sorts of preparations a lycanthrope would have to go through in order to make this transformation seem plausible, if not entirely possible. For instance, what would someone have to eat to support an increase in size, a reconfiguration of bone and muscle structure, and an extensive growth of hair? What sorts of exercises or therapies might be useful or necessary to help people through this painful process? Are there perhaps any good examples of animals that do something like this, and how do they prepare for it? [Answer] Science (not pseudo) is identifying that certain genes are active in different parts of the year. Most recently: [Seasons May Tweak Genes That Trigger Some Chronic Diseases](http://www.npr.org/sections/health-shots/2015/05/12/406139368/seasons-may-tweak-genes-that-trigger-some-chronic-diseases) (When I say recent - that's from May 12th, 2015 and today is the 13th). > > A study involving more than 16,000 people found that the activity of about 4,000 of those genes appears to be affected by the season, researchers reported in the journal Nature Communications. The findings could help explain why certain diseases are more likely than others to strike for the first time during certain seasons, the researchers say. > > > If one wanted to stretch this, the combination of a virus (inserting genes) and a monthly trigger of the expression of the genes inserted by the virus would not be that far fetched at all. The transformation, again stretched from what is present in reality, isn't implausible either. Plants such as the Venus fly trap can demonstrate very rapid growth in a very short time (it is rapid swelling of the existing cells). Other mechanisms could include very rapid growing tumors that are rapidly consume stored energy (accumulated over the course of a month) to grow. Upon the conclusion of the night (a wonderful time to bite and spread the virus), the cells would experience [apoptosis](http://en.wikipedia.org/wiki/Apoptosis) (the virus doesn't want to cause its host to die from the prolonged depletion of energy that the tumors would demand) - except for the cells that start the next cycle. [Answer] If you want something vaguely plausible in a scifi setting then you might go with a chrysalis. Every month would be far too fast and the change happening in a week would require high-scifi stuff like nanotech for anything the size of a human but you could have some kind of vaguely biologically plausible cyclic transformation if you allow more time. You could probably spin it as some kind of parasite which causes the transformations which eventually reverts you to human form to hide as part of some kind of cyclic lifecycle. This also gives you an excuse to make your werewolves immortal like Turritopsis dohrnii. <http://en.wikipedia.org/wiki/Turritopsis_dohrnii> The human ages and at some point feels a massive urge to eat. They fatten up then feel the urge to find somewhere secluded where they curl up and exude a chrysalis. A few months later your werewolf crawls out. Drama happens with wolf form and others are infected and eventually the wolf form feels the urge to find somewhere secluded again where it pulls the same trick to turn back into a youthful human who crawls out with vague memories of doing something terrible. [Answer] **Requirements for Transformation** In order to perform this transformation in a relatively short period of time a day, our lycanthrope is going to need a lot of calories. A lot. Consider that active male teenagers are well known for consuming impressive quantities of food on a daily basis while undergoing their growth spurt, a lycanthrope about to undergo a transformation will have similar caloric needs in a vastly compressed time frame. **Calcium & Phosphorus Requirements for Bone Growth** According to this [article](http://www.doitpoms.ac.uk/tlplib/bones/structure.php), the ratio of calcium to phosphorus is 5:3. If between the ages of 10 and 20, the average human male accumulates about 17 pounds of bone to achieve a height gain of 15 inches, that means our lycanthrope needs to consume 0.5 lbs of calcium for each inch of height gained. This quantity doesn't account for any increases that might be required for increased bone strength as a result of the [cube-square law](https://en.wikipedia.org/wiki/Square-cube_law). Please note that 0.5 lbs of calcium is just for structural growth. Calcium is also an electrolyte so you'll need extra to counteract losses through sweating or urination. In terms of food consumed to get this much calcium, assuming a dry skeleton is 20% of total body weight, our lycanthrope will need to eat the bones of two chickens for each inch of height he grows. **Protein Requirements** Speaking of chickens, a 140 gram (5oz) [chicken breast](https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=grams%20of%20protein%20per%20chicken%20breast) offers 43 grams of protein. For each inch a human male grows during puberty, he gains two pounds of muscle. Since muscle is approximately 80% water, each inch of growth requires 181 grams of protein (and 726 grams of water to hydrate the muscle (about a 3/4 liter)). The lycanthrope must eat four chicken breasts to get sufficient protein to grow an inch. In addition to the chicken breasts, he will need to drink half a liter of water just to hydrate the new muscle. Ha! This is working out nicely, each inch of growth for the lycanthrope equals two chickens for calcium and protein. Better eat the whole chicken though instead of just the breasts because dark meat has lots of fat in it. **Digestion Caloric Intake** Each calorie a human consumes carries a 10% digestion [cost](http://www.livestrong.com/article/320370-how-many-calories-does-digestion-use-up/) so all of our estimates thus far will need to increase by that much. **Maximum Temperature** Brain damage in humans happens when body temperatures go above 107°F (41.6°C) thereby setting an effective limit on metabolic burn rates. Elevated body temperatures may inhibit some metabolic reactions (though I'm not biochemist so I can't say for sure). Increased body temperate means lots of sweating, so he will need even more water and electrolytes just to stay alive. **Thermal Output of Growth** To simplify calculations, let's assume the lycanthrope is just a water bag weighing in at 100 kgs at 35°C. Note that a nutritional calorie is 4.2 kilojoules. To raise the temperature of one gram of water by one degree Celsius takes 4.179 [joules](http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/specificheat.html). Assuming no heat loss, the lycanthrope has a 2.7 megajoule heat budget going from 35°C to 41.6°C. (I'm going to ignore natural heat loss through radiation or sweating. My physics are not that strong.) Let's say our lycanthrope is going for 2 inches of growth for this transformation. That's four whole chickens or 6 lbs of which only 30% is protein, fat or bone. We need to digest 1.8 pounds of raw materials. To make calculation easier, I'm going to assume a uniform digestion cost of 0.7 calories (2.94 kjoules) per gram. (Fat yields 9 calories or 37.8 kjoules per gram. Protein yields 4 calories or 16.8 kjoules.) 1.8 pounds is 816 grams. 816grams \* 2.94 = 2.39904 megajoules, or just under our heat budget of 2.7 megajoules. Keep in mind that this thermal output is just for digestion and does not include basal metabolic rates or the cellular work required for transformation. Regrowing bone and muscle is expensive so I would expect increased energy costs to do it. **Summary** Eating two chickens plus other foods plus drinking enough water is going to be a severe test of digestion. Buffering the minerals, fats, and proteins for use during transformation will also be difficult as the circulatory system can only hold so much. Reconfiguring muscles and bones in a day or so could be possible but growth that rapid is akin to extremely aggressive forms of cancer. In short, our lycanthrope is going to be a hot, sweaty, greasy, stinky, comatose mess during the transformation. From his perspective, it will feel like every bone is broken and every muscle will have [third degree](http://www.drugs.com/cg/muscle-strain.html) muscle tears. So either he gets really lucky with his transformation where it completes and he's completely healed or it's gonna take a few days/weeks to recover. Also, the lycanthrope can't eat solid food while transforming because his jaws may lack the strength to actually chew. So yeah, it's possible over a period of weeks but it's gonna be really really really uncomfortable. Transformation in less than a day isn't feasible. [Answer] On [this Answer](https://worldbuilding.stackexchange.com/questions/12994/how-can-a-shapeshifted-jaguar-perform-a-blood-transfusion-on-a-dying-person/13120#13120) I mused about science-based transformation details. For plausibility, *nanotechnology* is the magic word. He can't change mass or transmute elements, but could re-arrange atoms in the extreme case, or be put together with rapid transformation in mind so tissues can be reconfigured rather than rebuilt from scratch. He might look like a man/wolf on the outside but have some funny features on the inside, if he was examined medically for example. Bones might be modular, breaking and joining to form different lengths, or telescoping and not made of *bone* at all. Muscles might split into different bundles and re-attach to different points, without having to grow different muscle tissue. Different "brands" might stress different feature trade-offs. One group of enthusiasts might want rapid on-and-off transformation, or prefer "wolf-man" anatomy rather than full anatomic wolfness; others might go for the most authentic anatomy possible and need special IVs to aid the transformation. A problem with full anatomically correct transformation is brain size. If *people* are all simply ephemeral arrangements of nanotech utility goo and actually live in cyberspace, they could rez-up any kind of body they want at the moment, at any location in the world. If the physical brain is altered with nanotech, it could very well be smaller while still being the same architecture. Not modifying the brain, however, makes it much more plausible for a near-ish future nanotech world. That could be an issue, as the head would need to be large and have a large enough brain case not just in total volume but to allow the human brain to fit shape-wise. [Answer] My suggestion would be cybernetics, that would allow you to transform almost at will and also explain the increased strength and resilience of the creature. Imagine a wolverine-like metallic skeleton attached to or replacing the humanoid one, along with artificial muscle to reinforce the human ones and metal plating to defend the vital organs. Normally the enhancements are mostly inactive and beyond being a little heavy you look like a standard human. When they engage though bones telescope and expand to increase reach and leverage, close combat claws extend from the fingertips, and the jaw expands and metal fangs extend there for additional close-combat potential. Muscle that is usually coiled up stretches as the bones extend while the skin opens up revealing previously hidden folds. The newly exposed skin is covered in metallic wires that extend out to cover the body and provide some defense against electrical and ballistic while also being insulating (they also look like a lot like fur). There you go, instant cybernetic werewolf :) [Answer] Vast and varied are the environmental triggers for the expression of genes, so the door is wide open for you. Histones are structures which expose sections of the DNA to the rest of the nucleus for purpose of producing specific proteins. Many online resources source old text and incorrectly label the nucleus as the 'nerve center' or 'command center' of the cell. This is completely incorrect. The nucleus is more like a sex gland with a harddrive. Actual processing is done across the entire cell, and mostly in the cell-wall. Anything which can affect the cell has the potential to trigger the Histones to 'allow' the production of proteins. DNA also contains information on what conditions trigger which histone state, and its these 'conditional' genes which will ultimately influence over an organism's morphology. Human DNA probably already contains all the information needed to produce lychanthropic forms, all they lack is the proper 'triggering' mechanism. You're looking at an organism-wide alteration of morphology at regular intervals, which means you're going to have to, suppress, inhibit, or otherwise override the existing genetic conditional modifiers, and then you're going to introduce NEW conditional statements. Genetic engineering would allow lycanthropy to be a hereditary trait, the first generation would probably be conceived in a lab and and finding surrogate mother might whose body wouldn't reject the fetus could be difficult. Simply gene splicing wolves and humans won't do. You're looking at an extensive, horrifically clinical trial period while your geneticists develop and perfect their brood. If you want the condition to spread virally, the virus would be similarly engineered, except the trial 'participants' don't need to be grown form birth and so your research could progress faster. The implementation of Nanotechnology would be identical to the virus. The difference being the potential to 'program' or 'hack' the triggering mechanisms (if you can find the drivers!). I would opt for a slow, steady, more fluid and cyclical change. Our werewolf would be more 'human-like' during the new-moon, and more 'wolf-like' during the full-moon, and in some transitional form during the waning and waxing. I'd say the dietary requirements of maintaining a transformative state as roughly proportional to a propetually-stoned-teenager. [Answer] Upon reading the question, my first thought was the same as @Murphy - a chrysalis form that converts between the two. While that stage of life is still not entirely understood, the vast change in forms is clear. As for science, there are biological ways that this could happen, especially given our rapidly increasing understanding of genetics over the past few years. Some combination of altered [Hepatocyte Growth Factor Activator (HGFA)](https://www.sciencedaily.com/releases/2017/04/170418161901.htm) [(also here)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4102383/) activation/expression, [stem cell activation](http://www.embo.org/news/press-releases/2014/autophagy-helps-fast-track-stem-cell-activation), [imaginal discs](https://www.scientificamerican.com/article/caterpillar-butterfly-metamorphosis-explainer/) that the creature has at birth. There are a whole large variety of cell groups, cell types, and gene expression that could account for this type of thing. A vastly enhanced or evolved [homeobox](http://www.dnaftb.org/37/), perhaps? The funny thing about genetics is that it follows the old saying "the more we know, the less we understand." And also "truth is stranger than fiction." The past few years have seen scientists [create new DNA "letters"](https://directorsblog.nih.gov/2017/12/05/adding-letters-to-the-dna-alphabet/) (Floyd Romesberg and team), how [endogamic groups](https://www.edge.org/conversation/david_reich-the-genomic-ancient-dna-revolution) have specific markers in their DNA, which could include lycanthropy (why not?), really just all manner of interesting things. So, from a science-based tag, no... because it's not something we have any tangible evidence of. From a reality-check perspective, it's not implausible at all. [Answer] here are alot of great idea's here so i wanted to post my own. The only realistic one to me is the hybrid form. As a complete change of body plan is not workable in biology.there for your werewolf most remain humanoid. The way i would do it would be a a mix of stem cells cancer and virus all in one. This metamorphic cells or meta cells for short destory the human cells and replace them with the hybird ones in a form of cancer like repeated growth.this combined white hand ,leg and face boons made to come apart in to platelets and reshape in to claws legs and a muzzle .that gets you most of the way. The real hard part is paying the energy cost for the transformation. It would be huge and need vast amouts of bio mass. But you could get around this by haveing the werewolf store enargy as ATP in vast amounts. This is like storing fat only more effective. So what you have would be a larger , heavyweight human with high body temperature and crazy appetite. Then as a repose to strace hormones wold trace form in to a werewolf like monster. The side effects would be crazy alsome like things cooking and burning 🔥around the were wolf when tracesforming do to ATP porbouseing heat and the huge amount need to transform. thay would uncontrollably eat everything when trasformed do to the huge amount of enargy need to stay alive plus exstra to change back. How change back works would be the stame Mate cells . when the heman cells were destroyed /replace there dna replaced the hybird bna with in the meda cell. So when the hormon levels go down and there is the enough ATP with in the body the werewolf would change back. This maens that werewolfs would be not beable to tracefrom unless will feed and would beunable to change back until will feed. The transformation could be at will or a danger fight or felt thing. Brain were wolfs would change uncontrollably and die vary qickly. (Hours at most) If you want the full moon thing you could say that werewolfs most transform mouthly or there body would over hate killing them bo to stored ATP reasing the body heat. In combat werewolfs of this type would be faster stronger and able to heal super quickly . plus there claws could beused in human form and thay would be uneffect by exstrame cold. Some side notes Tails If your were wolfs have tails then thy would be prehensile tail as humans carry porment bna already for prehensile tail. This also maens thy would have tails in human form as will but most like there remove at burth to blend in with humans bether . Hair The hair all over the werewolfs body could be a side effect of the high metabolic resporashion need for there trans formashion as keratin the porten hair is made form uses byproducts of resporashion in its make up. Meaning change back would creat more hair and lead to alot of shading. Think skin Were woulds could have exstreamly think skin makeing them hard to cut or burn bo to the body reuseing keratin in the skin created when transforming. Armer werewolf Werewolfs would ether a offout or sub spaces of human and could have sub spaces of there own. One cold have bio armor instead of hair all over its body as keratin is used to make boon horns and other hard biological materials. ]
[Question] [ I was wondering if it would make sense to hollow out an asteroid to use for a [generation ship](http://en.wikipedia.org/wiki/Generation_ship)? Also, might it be a good idea to use hollow asteroids for any kind of long distance space ship? I'm thinking you can mount engines on the outside, you have some great hull protection, there may be some handy ready resources, it would work for insulation so less energy would be needed to keep things habitable, and going at high speeds small objects would pose a much smaller risk to the integrity of the ship. So other than mass, are there any other big drawbacks? [Answer] As already mentioned the problem with this concept is the mass, you're needing to accelerate the dead mass of the asteroid as well as all the working bits. There are possible some drives where that would not be a problem (for example using a warp drive of some kind, although even then you would need to synchronize velocities with the destination when exiting warp) but the options are pretty limited and even warp drives would most likely need more energy for more mass. The advantage though is the raw materials. When setting off on a voyage where population may expand, advances may be made, etc, then having a huge chunk of raw material available to refine, hollow out, re-purpose, etc could be very useful. But more useful than just transporting a stockpile of already refined materials? Probably not. Although with the refined materials you do run into the issue and benefit of having to decide in advance what you need rather than just hauling a huge chunk of rock and hoping it has something useful. [Answer] Unlike metal or plastic, many types of rock are slightly porous, so over a long time, atmosphere could slowly leak away. This might not matter for a ship making journeys of a year or two, but over generations, there could be a significant loss of gases unless the whole interior was covered in some sort of sealer that would last generations. Another drawback of an asteroid is that there is a lot of unnecessary mass that would have to be accelerated. Better to build a ship as light as possible in order to reduce the cost of acceleration and deceleration. On the other hand, a sufficiently large asteroid would also provide good protection against interstellar radiation, and if the species manning it are sufficiently paranoid or justified, an asteroid would provide more camouflage against enemies than a manufactured ship. [Answer] So long as we're not bumping into a [logistic growth ceiling](http://hopsblog-hop.blogspot.com/2016/02/limits-to-growth-logistic-vs-exponential.html), I don't see a strong incentive to leave our solar system Along with generation ships comes the assumption of a non solar power source and the technology to engineer closed ecosystems-- the Main Asteroid Belt would be open to real estate development. I see several logistic growth ceilings here. I suspect it'd take centuries or millennia to fill the Main Belt. From there the Hildas are natural cyclers between the Main Belt and Sun-Jupiter Trojans. (See this [vid](https://www.youtube.com/watch?v=yt1qPCiOq-8) where first half shows Hildas, 2nd half Trojans). When the Main Belt and Trojans are filled up, there's the Centaurs as well as moons of gas giants. After those are filled comes the Kuiper Belt. And then the Oort Cloud. By the time we fill the Oort, our civilization will probably have many millennia of experience building biomes from ice balls as well as using fusion power. Given a civilization with this infra structure and capabilities, I'd construct the generation ship in the Oort. On the boundaries of the the sun's gravity well, it only takes a small burn to drop the ship to a perihelion deep in the sun's gravity well. It'd take a few centuries for the ship to fall from the Oort to the inner solar system. But given city states throughout the Oort, spending centuries dwelling in artificial biomes is already the norm. When 1 A.U. from the sun, the ship would be traveling about 42 km/s. If perihelion is within .1 A.U. from the sun, perihelion speed is about 133 km/s. Doing the burn near the perihelion can give a substantial [Oberth](http://hopsblog-hop.blogspot.com/2013/10/what-about-mr-oberth.html) benefit. If the ship does a 55 km/s burn near perihelion, it'd pick up 133 km/s Vinf. Of course 133 km/s is only .0004 C (speed of light). It would take around ten millennia to reach Alpha Centauri and longer for other neighboring stars. If the ship had a drive capable of reaching .1 C, solar Oberth benefit would be of little consequence. In this case I might depart directly from from an Oort object a light year or two out -- as close as possible to the destination star. [Answer] Asteroid, no. # Use comet True, you need to match velocities with comet. Intercepting it and bounding in space will be difficult. But once you do, you will have a **lot** of water, already at pretty nice velocity. So you need to spend fuel only to shot working bits, and get drinking water for "free". What's nicer, you now have empty fuel and oxidizer tanks. And sunlight. So you can use electrolysis to refuel from asteroid's water. And you can use water as an emergency source for breathing oxygen. [Answer] Parts of the asteroid itself may be used as fuel. A large metallic one could be launched electromagnetically, or parts of it could be magnetically fired backwards to thrust the "front" end. [Answer] It would be a very good idea, especially if they could be fitted out as mining colonies as well as transports. Where they may be utilized as base-points to bring materials mined throughout the area for processing and conversion into other products, vehicles and/or habitats. The problems would be the energy required for propulsion and the processing of materials such as metals and manufacturing, which would almost have to be nuclear. It certainly would be worth it, considering the cost of launching processed materials and objects into space from the Earth. Another scenario where they would be extremely beneficial would be in repetitive trips to other planets within the solar system. If they could be arranged into well timed orbits, for example between Earth and Mars, explorers could jump on one as it passed Earth and get off as it passed Mars. If they could be made to rotate then there would be the benefit of centrifugally generated artificial gravity. So if two, three or four asteroids could be arranged in very well-timed and stable orbits then there would be an asteroid passing Earth and Mars on a quarterly schedule. Once arranged the fuel savings would literally become astronomical, since they would not need to be accelerated and decelerated for each trip . They could be used as shielded taxi's and also as depots for spare parts and provisions. Ultimately the asteroid fuel problem should be a priority, since building any very large ship from the ground on Earth would be prohibitive at our current level of tech. PS Not all asteroids are mud. Some are solid rock and/or metal. I like the idea of nickel/iron as the hull of a ship, since the radiation hazards in space are not negligible and outside of the solar system radiation hazards are apparently downright outrageous. Asteroids are the only way of doing any major travel at our level of tech, mainly because the radiation will kill or blind 20 out of 100 long range astronauts within a year and the hazard dramatically increase with exposure time. ]
[Question] [ Dragons are often thought to have impenetrable scales. If dragons were to shed them it would obviously make them far more vulnerable for a period of time. This on the other hand would make them easier to be hunted. So the question is pretty straightforward. Would a dragon, based on modern science, shed their scales? Assuming the dragon is just overgrown lizard with fire breath, wings and scales made of metal-rich mineral composites. If so how long would the process take? Dragons are very common theme but their biology isn't explained often in detail. Metal-rich mineral scales are most easily explainable. Minerals are heat resistant to withstand their own flames while metal would have it's own advantages. Dragons would eat minerals to grind their food while the excessive metal would come from equipment worn by humans they eat. So in short dragons are what they eat. If they eat valuables they might have golden scales while starved dragon wouldn't probably even have scales to begin with. [Answer] **Yes** And it doesn't compromise their ultra-tough scales at all. Whether you think in terms of a snake (the entire skin is shed at one go) or a lizard like an iguana (the skin flakes off in patches over time), you still have the same basic process... the scale doesn't actually leave the body, leaving the snake or lizard defenseless, the scale underneath grows beyond the limits of a top-layer of skin, and the skin must be shed to make room for the growth. The scale is still there, and in the case of your dragon, still very much armored. Yup, they'd shed their skins... and an ugly biohazard that would be! [Answer] Reptiles are not vulnerable in the way in which you seem to be thinking when they shed their skin, so I do not see why dragons would be. Basically, the new scales grow under the old ones, so it's not as though, when they shed that reptiles are softer during that time. As to how long it would take, that would depend on the process. Snakes can take two weeks... Lizards: Iguana, Geckos, Chameleon… > > Lizards shed their skin by parts, being one of them the change of > colour: the skin get paler on the bits where it starts to fall off. > Skin renovation usually starts on the head or along the spine and > regularly ends on the tail. Although each individual has its own > shedding rhythm, it usually takes a week or two for lizards to have > their skin wholly shed. [SOURCE](http://www.vivapets.com/article/reptiles_skin_shedding/374) > > > Snakes > > Snakes have a rather particular shedding process. Their skin comes off > all in one piece and turned inside out, shaping into a sort of pale > skin tube. Before the process begins, most snakes start presenting > hazy, whitish or bluish eyes. Colubrids tend to get a lighter colour, > while others, such as the boidaes, turn into a lot darker. The skin > shedding process will only set off once the eyes return to their > regular colours, which is usually the next day. [SOURCE](http://www.vivapets.com/article/reptiles_skin_shedding/374) > > > Alligators and Crocodile > > Alligators and Crocodile skin is scaly and often will come off in > individual scales instead. So, while alligators shed their skin like > other animals do, their “molting” is much different than other > reptiles. Just like most animals including Mammals, a healthy > alligator will continue to shed its scales regularly, rubbing up > against trees and rocks to rub off the dead skin. > > > As Alligator shed their scales, newer, larger, and denser scales are > formed as the Alligator grows in age and size. This makes their skin > incredibly dense and strong, resistant to the abuse that would tear or > scar the skin of most mammals, including the false theory that their > skin is “bulletproof”. While not bulletproof, alligator leather is > extremely durable and this makes it a popular leather to use in > products and upholstery where a very dense yet attractive leather is > needed. [SOURCE](http://www.alligatorleather.net/alligator-skin-shedding/) > > > Vulnerabilities will depend on how you work it--they might not be able to move as well, like lizards sometimes, or their eyes might be compromised for a short time. Dragons are likely more in line with gators than they are lizards, though you could work their first large molting or shedding like a lizard when they are transitioning to adulthood, and then do the rest like gators. It's fantasy, so you can do whatever serves your narrative best. The idea of your dragons not having scales at all if they don't eat minerals is pretty darn contrary to biology. While it's fun fantasy flavor to add to the scales depending on what they eat, it would be pretty strange for them to be scaleless--they either have them or not. Now, there are scaleless snakes--but they don't develop scales later. And scales, biologically, are there to help with a number of things including temperature regulation. While there are scaleless snakes, this is a mutation, Even the snakes considered scaleless often have ventral scales, along the belly, helping with their movement and locomotion. Scales are made of keratin, and can be super tough. I can see the replacement scales having more minerals in them as a biologic process as they consume minerals, but even on a fantasy biologic level I don't buy them being completely without scales when they are young--the regular scales are the blueprint the mineral-filled ones can show fitness. The closest biologic template I would say works is flamingos. They have feathers no matter what, and are born with grey feathers but their diet changes the color to pink. They don't not have feathers until they eat what changes them. So your dragons will always have scales, but not every scale will have the minerals or some will have more minerals than others. The minerals are added to the template structure as in [fish like koi or birds like the flamingo.](https://io9.gizmodo.com/how-food-can-change-the-color-of-flamingos-fish-and-e-1225948385) If you want a mineral example, look no further than humans. Colloidal Silver is used as a treatment, and it [turns people a greyish blue](https://health.howstuffworks.com/skin-care/problems/medical/colloidal-silver-blue-skin.htm). We have skin with or without the silver, but it tends to gather in the organs and stay, one of those happens to be skin. [Answer] Look at crocodiles they shed scales one at a time so there is never much risk. This is similar to how humans shed hair, individually so 99% is always there. And as JBH said it is only the outer most layer of the scale that is shed. Or course if you are worried about replacing the metals just have them eat their shed scales,some reptiles do something similar and eat shed skin, then they can just keep concentrating metals in their scales. they do not need to eat minerals per see, if they are using metal rich ores for gastroliths then they will have a steady supply of metal. living animals with gastroliths can be quite picky about which stones they swallow so licking and picking metal rich ones would not be unbelievable. [Answer] The video game *Monster Hunter* plays around with this idea with a few of its dragons like the [Kushala Daora](https://www.youtube.com/watch?v=Xjc1X3O0Xxs "Kushala Ecology"), but most notably the flagship monster, the [Gore Magala](http://monsterhunter.wikia.com/wiki/Gore_Magala "Gore Magala") and its mature counterpart, the [Shagaru Magala](http://monsterhunter.wikia.com/wiki/Shagaru_Magala "Shagaru Magala") in the 4th installation of the series. As others have mentioned in their answers, how they handle it with the Kushala is similar to a snake, and the Gore Magala by individual shedding of the scales like a crocodile. In fact, they introduce an ["intermediate state"](http://monsterhunter.wikia.com/wiki/Chaotic_Gore_Magala) where the juvenile scales of the Magala have partially molten away. It's an interesting case since the shedding of the scales themselves are incorporated into the game mechanics and impact the behavior and biology of the juvenile version of the dragon. [Answer] Yes. *Every* dragon, realistic or not, has a good mind for revenue generation. It has never been realistic for these giant creatures to simultaneously want to sleep on a bed of gold, but not want to sell their waste products for huge amounts of money. Dragon scale is a superb all purpose material, and the average dragon can make millions selling merely their unwanted old hide, which not only increases their equity, but flatters their vanity. If there's any way that they can ditch their hide, they will take it. ]
[Question] [ Imagine a meta-human, one engineered to be immortal. A combination of cybernetic enhancements, genetic engineering, and other scientific modifications have made it so this human *will not* die from aging, and is *very* hard to kill. They are designed to be a magnificent soldier, and if they start suffering psychological issues, it's intended that their mind can be fiddled with to "fix" them. Things happen. Rebellion, war, apocalypse, shifting society, new laws - There's so many ways it could happen. End result: This immortal is now free. The cost? There are no others like them. Further Information: * Said Immortal views themselves, being immortal, a bit abhorrent to begin with, the results of people playing with things they shouldn't be playing with. They are, however, areligious. Not atheistic, exactly, just not worried about the question of religion at all. * Given the above, this Immortal would reject anything akin to worship. Not that it would stop some people. * This Immortal was designed to function in both a communal setting and an individual setting - Being a soldier, they should be able to play well with squadmates, chains of command, and the like, but they also need to be able to function alone for an extended duration. Personality wise, they tend to be more of a loner. * Similar to [this question](https://worldbuilding.stackexchange.com/questions/13699/how-would-the-constant-presence-of-an-affable-undemanding-immortal-affect-a-soc), HOWEVER, I am not worrying about the outside world, more of how it would affect the Immortal's mind. Given this setup, what sort of psychological impact would this have, over the span of centuries or millenia, and how would this affect the Immortal's actions/character? I'm looking for <1500 years. Beyond that and society tends to do strange, unpredictable things. Things I am **NOT** looking for: * Biological/genetic/etc implications. I'm not interested in the *how* - That's the scope for another question, perhaps. I'm also not interested in biological effects, such as being a carrier for diseases, etc. Again, another question. * Creating more Immortals as the solution. The plot involves said Immortal being strongly against the creation of *more* immortals. See Further Information above. [Answer] Given we're talking about affect on the mind, let's dive into the psychology and sociology that make up a 'grain of sand on a beach'. Humans are social beings. We crave meaningful interaction with other's who are like-minded enough to get along with (Tribal nature of humans), but we can value those different enough to offer us a greater chance of survival should something unexpected happen (think having a nerd and a jock being 'best friends' for survival reasons). For this reason, it's likely your immortal will feel like an outcast no matter where they go. After all, they don't age (everyone else does). They're a soldier, not too many they'd interact with are. They're 'made', everyone else is born. They stick out like an cat at a dogshow, even if only in the immortal's mind. What's more, you get 'lost passions' syndrome. Meaning even if this immortal overcomes internal stumbling stones (self-loathing, 'being a freak'), even if they find friends that accept them as they are (whether they know is irrelevant to my point), they will outlive that person/those people. They will grow close to them, watch them grow old and feeble, and eventually die--leaving our immortal alone. This is a festering wound in the mind of someone that will have to shut themselves off emotionally to survive. They will eventually learn to never get close to people, because they will either treat them like a freak, or they will die. Neither option is good for the immortal's mental well-being. Compounded by hundreds of years of this? The more social a creature this immortal is, the worse the prognosis. The less social this immortal is, the worse the prognosis. You face a powerful warrior that will eventually develop either an inferiority complex or a god complex, which will be couched in pain, rejection, and loneliness. Being alone for centuries is not good for anyone. Loner or no, social butterfly or no. It leads to thinking to pass the time, and that thinking slowly grows more and more warped without someone to bounce said thinking off of to ground them back in reality. All in all, this immortal is a ticking timebomb. Good luck with that ;) (it would make for one hell of a story I'd love to read!) [Answer] > > Said Immortal views themselves, being immortal, a bit abhorrent to begin with, the results of people playing with things they shouldn't be playing with. They are, however, areligious. Not atheistic, exactly, just not worried about the question of religion at all. > > > The phrase "Things man was not meant to know" is actually religious in context. Viewing themselves as abhorrent because man was not meant to tinker with certain things--that's a religion-based idea. That's where it comes from, because in the humanist view, man has a mandate to tinker--nothing is the purview of God. It might be something a humanist might DECIDE for practical or moral reasons that we shouldn't be doing, but this grand idea of "people playing with things they shouldn't be playing with" implies that there are some kind of universal rules as to what is allowed and what is not--which, hey, that sounds a lot like something God would be doing. My point is--if they hold the view of abhorrence of themselves and it comes from that idea, they may subconsciously be holding on to the idea of God, even if they don't realize it. > > Given the above, this Immortal would reject anything akin to worship. Not that it would stop some people. > > > Strangely enough, if the Immortal did believe in God, they would be more likely to reject worship because they might believe that it isn't their place to be one. If they don't believe in God, then it actually makes more sense that because they are the closest thing to it, they might actually allow it--protecting folks as best they can if they are good, and taking advantage of all the benefits with little moral computions if they lean more towards selfishness. > > This Immortal was designed to function in both a communal setting and an individual setting - Being a soldier, they should be able to play well with squadmates, chains of command, and the like, but they also need to be able to function alone for an extended duration. Personality wise, they tend to be more of a loner > > > Even loners eventually make friends. The usual psyche impact we see is dealing with the pain of all their friends and loved ones dying, and maybe avoiding relationships of any kind with people because of it--just moving from place to place. These summarize an excellent [cracked article](http://www.cracked.com/article_18708_5-reasons-immortality-would-be-worse-than-death.html), with my own flavor thrown in: * **Eventually they will get trapped under something.** Given an infinite amount of time and earth conditions, this will happen. And it might drive them insane. They could be trapped under something for YEARS. * **Memory issues.** So you say that " if they start suffering psychological issues, it's intended that their mind can be fiddled with to "fix" them" however after a generation no one will be left who knows how. There's only so much room on our hard drive, and it's possible they may have holes in their memories for a lot of different reasons--as a protection psychologically or because they don't need to recall everything and old memories might get overwritten. Doctor Who's [Ashildr, aka Me](http://tardis.wikia.com/wiki/Ashildr), developed these problems, and it might be a good model. An immortal who can't remember is also something you will find throughout lit, comics, and movies. It's a thing for a reason. Also consider severe head trauma, which may happen to them at some point, depending on their abilities. They might heal, but that doesn't mean they will recover the memories. Not remembering might have a psyche impact, but this is something for the individual. * Your perception of [time speeds up with age.](http://everything2.com/user/Professor%20Pi/writeups/Why%20time%20appears%20to%20speed%20up%20with%20age) For a five year old, one year is a fifth of their lives--and it seems like forever. For a fifty year old, a year seems to pass very quickly because it's a smaller percentage of the life they have lead so far. This may lead to insanity--it certainly might make said immortal callus. From the article: > > So when you're 100 years-old, a minute will seem six seconds long compared to a minute when you were 10. If you live for 1,000 years, a 50-year marriage spent with a woman for her entire adult life, will have the same significance to you as the girl you dated for a few years back in college. > > > What this means relationshipwise is that regular humans may consider their relationship more meaningful than the immortal considers them. Six months of friendship is a significantly long time for a 6 year old, and matters to them greatly. You could argue that is why everything seems so damn IMPORTANT when you're a kid or a teenager. And you get frustrated when some adult comes along and goes "eh, it'll be fine. Or it won't. You'll make new friends/be able to see it when it comes out on video/find another pair of jeans/get another job/find a new girlfriend." The adult has perspective and experience--sometimes they do remember that old urgency, and understand that it matters to you, but your immortal may view adult humans crying over death in the same way that an adult human views a crying kid who has lost their toy. The adult understands that it's very important to the kid, and they may want to comfort them, but they are unlikely to feel the same sort of deep empathy that they would feel if they were comforting a relative who had just lost a loved one to death. [Answer] The psychological impact would be, over time, no different than it is for a non-engineered, typical lifespan human of naturally occurring high-level soldiering skills, for the very reason that they are "magnificent" soldiers and still basically human. **Learning and Adaptability** In order to be at that high-functioning level, this human is extremely intelligent, which means they excel at two of the best human traits: the ability to learn from experience and the ability to adapt to changing environments. In the beginning of their life, there could be a transition period where initial adjustments to handling their immortality challenges includes dramatic ups and downs in emotional response, but the high level of intelligence and learning capability will make this phase shorter than it would be otherwise. **Adjustment Period** If at first they shut themselves off from others emotionally during the adjustment period, it will likely not last long, as they will be able to quickly learn to regulate how emotionally invested they allow themselves to be, and will adjust their emotional involvement as they see is best, learning as they go. You are, after all, talking about a very high-functioning individual; they will adapt. It is unlikely they will continue to see themselves as being any more or less valuable than any other living being since with more time than most to add to their intelligence the wisdom of experience, they will reject being overly judgmental, including about themselves. **Over the Long Haul** Because they retain social functioning drives and skills, yet have a tendency to be a loner by personality, they will most likely over the longer period of time, vacillate between periods of social interaction and periods of reflective seclusion. It would be likely that some of the seclusion periods would be shared with anywhere between one and a dozen other like-minded people, meaning those people would be similarly intelligent enough not to judge the immortal for being different than themselves. This provides satisfaction for the social interaction without being too much for the loner tendency. They will incorporate procreation and highly involved interpersonal relationships like friendship, partnership, and family living within the more social periods. Having been through it a time or two before, they will be prepared for and more easily handle the loss of loved ones. Multiple cycles of these experiences enables them to adjust how emotionally connected they allow themselves to be in different relationships. They will get better at adjusting this connection appropriately to the needs of their companions, choosing to commit to high levels of connection for children and some adults that need the extra connection. They will get better at choosing the right people with which to engage. They will spend some time during their solitary periods being less active and more reflective, reviewing past experiences and what they learned from them, as well as exploring new ideas and contemplate in which direction to take their lives when they are ready to enjoy another adventure. **Self Actualization** They will achieve self actualization, which the dictionary defines as: the achievement of one's full potential through creativity, independence, spontaneity, and a grasp of the real world. [Answer] I would think that the idea Neal Asher had in his Polity Universe is quite fitting. In that setting, people can live for hundreds of years biologically, and survive many otherwise deadly happenings. Can you imagine what might be the number one cause of death? It is **boredom**. People get reckless or even outright kill themselves. People strife for something in their lives. Our sensory apparatus is built for perceiving *differences*. You can see this in the touch and heat reception of the human skin - the brain is going to dismiss the information about it, if it is more or less constant. We get accustomed to the feeling, and it will seem normal. This is also the case with the visual apparatus - you simply cannot be aware of differences without movement - *change* - in the images you perceive. It is also known that repetetive experiences will dull the senses, up to a point where people just live to be alive and feed their children. Now imagine you have to endure this for several lifetimes. Even though the individual activity may be interesting, it is likely that even these casual "new experiences", even though some of them are extremely interesting and/or even traumatizing for a normal human, will be dull and increasingly boring for the immortal. So, I would guess there may be another three things (in addition to what other answers already tell) that will heavily influence the Immortal psychically. 1. Looking for the *new*: The immortal always tries to experience something new, interesting, different. 2. Nothing is *really exciting*: The immortal is disillusioned and noninvolved, why would you care to intervene if, in the end, everything stays the same / nothing is really different to what he already experienced several times. 3. Looking for *more risk*: Since the immortal already has experienced so much, he might increase *risk* of death / failure in his actions, being more reckless, accepting more challenging missions, even going in without backup in a firefight, to be able to experience the *thrill* of something new, different, *exciting*. [Answer] I don't get the "very hard to kill" thing. Imprison them and what, they just go on stand-by for the next million years? Shoot them in the head and their brains grow back exactly as if it never happened? If so, then you're talking magic and you can have them be, psychologically, anyway you want them to be. I know you said you weren't interested in the biology (meaning in the science) but why bother asking us here then, this forum is based on answering questions based on the science. Assuming you have a creature whose brain can be replicated and modified at will (which is about what you describe, it would be some sort of regeneration, possibly in a tank) then their psychological stability wouldn't depend on very long term effects, since those are exactly the ones easiest to wash/wipe away. We can also debate how much a human brain can retain, how much of my 20th year will I remember if I were to be a healthy 120 year old? I'd guess not much, there will be natural turn-over (restructuring) and memories will erode over time, leaving just the most emotional (both positive (love, accomplishment) and negative (pain, despair, failure) but especially the positive). A stable personality will be forgiving - it's like the AA prayer: Give me the patience to bear those things I can not change, the strength to change those things I can, and the wisdom to know the difference. S/He would rapidly become rich (the power of compound interest). His/her intellect would become no greater than whatever s/he was given, IQ wise. S/He would be forward oriented, possibly to unusual extent. {what, you killed my wife? well, since I don't think you will do it again, let's go out and grab a beer.} Why? Because dwelling on past misfortune and mistakes would rapidly become all encompassing. Now, whether such a person is more like Christ or more like Anton Chigurh depends on programming or predisposition. S/He could be as sociable or asocial as you like. I don't think they'd tend to have many long-term friendships (spanning decades), but that depends on how good they are at letting go. (The better they are, the more "even keeled" they'd be, the worse they are, the more cyclical their disposition could be). Quick to anger? Maybe. Quick to forgive? Maybe. But either way forward looking. Wo/Man of action? not necessarily. More of an Ivory Tower theoretician? maybe, maybe not. I think most people are afraid of death, and s/he would be, but would probably be a lot more likely to take physical (and emotional) risks, given their more durable physics. Unless they (whoever they is) did a mind-wipe frequently, the Lazarus man would have to be forward looking, more so than most, I think. Other than that, I see few constraints. ]
[Question] [ Names are important, in fact one could argue that they are as important as the people behind them. They help add feeling to the characters and likely come from a specific cultural or subcultural group. Because of this, names need to fit in with your culture or you will have one big mess, after all, would you expect a Brit to be named Hakasaru? Or a Russian named Yoruba? It is important here that the naming customs of you culture fits in with the culture, but what is the best way to go about doing this? How can I make sure that the naming customs of my culture make sense and fit in with the culture itself? [All Culturally Correct Questions](http://meta.worldbuilding.stackexchange.com/questions/3960/culturally-correct-series/3961#3961) [Answer] ## I Said Do You Speaka My Language One thing about names is that they are pronounced like regular words. That's because often names actually are regular words. Consider, for example, that silly trope where boy meets exotic girl and she says her name is Mortihomoalbus or whatever and the boy asks, "What does that mean?" Invariable the girl has some cheeseball answer. Many names are derive from words already in common usage in that language. For example, a lot of family names come from trades (like Baker). A lot of place names are descriptive (like Buena Vista). And a lot of family names incorporate their place of origin (like names of nobility but also like Jesus of Nazareth). ## Hooked On Phonics Given the above, you need to start stringing some syllables together. You said you don't want to use real Earth names so I recommend you start imagining what the language of your culture sounds like. You can start off really basic and bombastic. I don't mean to offend, but consider for example how the movie "Team America" characterized Arabic as "durga durga," or how the Muppets Swedish Chef made a lot of "herdy birdy" sounds. Then, consider all the other the awful stereotypes that people have when they are making fun of Chinese-speakers, the French, Jamaicans, and other languages. These sounds are the types of sounds (whether real or imagined) that are associated with a culture, which includes both regular words and also names. ## A Rose is but A Rosé More on the above point, consider also that different cultures will literally convert the same name to fit their language. Like the name "John." A name from the Bible, originally Hebrew "Yochanan" which then grew in popularity among Eastern Orthodox so you get "Yannis" and so forth but then also the rest of Europe where you get the German "Johann," the French "Jean," and the Italian "Gian." ## How Do You Identify Yourself Which brings me to my last point: why on Earth would an English guy have a Hebrew name? You know why: Christianity. Europe (and the Middle East for that matter) was crazy about religion for a long ass time and the plethora of names based on religious characters is a reflection of that. The Borg are super into order and "thinking as one," and their names are reflective of their hierarchical predilections. Cartoon cavemen are super into being stupid but strong and so you use onomatopoeia to get names that sound like bashing something with a club, "Klag" and what have you. (I guess Klingons are too, but I didn't want to lean on Star Trek too much.) Don't get me started on pop-culture versions of Native American names, "Sitting Bull" turns into "Dances with Wolves" and or whatever. 'Cos we all know Native Americans cry a tear when you litter. Ugh. The point is, names often come from whatever it is that the culture is holds in high regard. (Consider, for example, the bastard names of Game of Thrones.) But to summarize, if you are going to make up new names that are not based on existing Earth cultures, then I think you think about that culture's language and ideals. You can also consider historical events that brought cultures together, either through religion, conquest, slavery, trade, etc. Good luck! [Answer] In my opinion, the easiest way is to create a naming language. This is a subset of conlanging but only comes up with enough rules to figure out how to name things. If you do a search for "conlang naming" should be enough. I'd read through [Zompist's excellent Language Construction Kit](http://www.zompist.com/kit.html) for a lot more details and a pretty good introduction to that. It gives you an idea of how to come up with the syllables and the rules that chain them (that is why "Dylan" works but "Dylna" doesn't in English), that is probably one of the big ones for naming languages. You can fake it saying "here are the syllables I want to use, they can combine in any order." Once you figure that out, start coming up with components. So, say "vikir" is "river" and "town" is "pad". So river town would be padvikir or vikirpad. Or you decide on some rules where they combine (padikir, padikir, etc). Come up with rock ("stun") and then you can do River Rock, Rock River, Rock Town, River Rock Town. Come up with another and another, slowly build up the language. People names are pretty much like that. Smith was a smith, Silver started as a silversmith or miner. You build them up, occasionally reduce or combine things together. Do that a couple times and you have a naming language. You also need to decide on things like given/family names. Japanese does family name first (because family was more important). We do given and then family. There are groups that the last name is the name of your spouse or father. Others are name for the location of they were born (Joan of Arc). Come up with those rules and you have a pretty decent start on naming. [Answer] As a starting point, I would go to <http://www.behindthename.com/> and look through one language at a time, seeing where the names come from. Be sure to note which ones are borrowed from other languages. Hebrew names are sometimes entire sentences, such as Abidan, "God is my judge," but while some English speakers have that name, we don't name people "God-is-my-judge." In Japanese, people are often named from things in nature, like snow and lilies. It's also common (though not as common as it once was, I think) to name people after their birth order; Ichiko "first daughter" is an example. Another interesting thing from Japanese is that there are "name suffixes" that indicate which gender the person is: e.g. "Ko" ("child" or "daughter") and "na" ("greens") for girls, "rou" ("son") and "to" (depends on how it's spelled) for boys. Most of the time, the literal meaning of these suffixes aren't taken into account. There are also cultures that have traditionally named people after the first thing their mother sees after the child is born. Some cultures like naming kids after heroes (like Jesus in Spanish or Alexander in English), while other cultures consider it bad to give someone a name too closely associated with legendary figures (like Amaterasu in Japanese). Traditionally, Christian Europeans have named their kids after people in the Bible, sometimes even antagonistic characters (but never Satan or Devil). Catholics also named (and still name) people after Christian saints. Hindu Indians sometimes (often?) name people after gods and goddesses. One more thing to consider would be how receptive the culture is to new names or variations of names. Maybe there used to be a lot of new names like "clear water" or "clear weather" that people made up on the spot, but these days the number of acceptable names to choose from has diminished and people generally choose from a pool of well-known names. I hope this is helpful. [Answer] To make sure that the naming customs of a culture make sense and fit in with the culture itself you can, and maybe should, actually list those customs. As a starting point you may take the naming customs of a culture that you are familiar with; be *sure* that you are familiar with the naming customs of that culture, maybe do some research. List those customs, then begin tweaking them to fit into the imagined culture. Don't forget that a culture may consist of two or more subcultures, possibly with different naming customs; for example, even Europeans are able to make an informed guess on whether an American is a white Anglo, a Hispanic or an African-American based on their name. Ah, and about Hakasaru the Brit. No, I would not expect a British person to be named Hakasaru; but if a British character in a novel was named Hakasaru I would expect an interesting story explaining the name; maybe they were named after a Japanese friend, teacher, or lover; maybe they are from an ethnically Japanese family which came to Britain under some peculiar circumstances; maybe they are part of a community of ethnic Japanese British citizens; and so on. ]
[Question] [ Related to my previous question : [How to live in an underground city?](https://worldbuilding.stackexchange.com/questions/23882/how-to-live-in-an-underground-city) The refugees managed to live in their underground city with the few resources they can find. They are prepared to fight if necessary. But they do not want to fight if they can avoid it. They are afraid. If the army does not find them, they might avoid fighting! *Things you might need to know :* * The place where they are building the city is in the middle of nowhere. A land full of rock with a small river and some grass on top. Before their arrival, the underground network of galleries looked like a few holes in the ground from the outside. * They can use some magic to build or move rocks (nothing more than what medieval technology could do, but faster) * They need to go outside quite often (I'm afraid this will make their paths hard to hide) * They have children and animals (sheep for example) and perfect silence seems impossible. *How to hide the city : my currents ideas* * Make the path from the army to the city very difficult to traverse: piles of rock in the tight passages, traps (what kind ?), guerrilla. But my refugees are not warriors, and the enemies are. The more they avoid contact, the better. * Watchmen, of course, will give an alert when the army approaches, so emergency actions are possible. But what actions can they take aside from hiding everyone in the deepest, darkest places? * Restrain or close holes/entries. That will make life in the city less comfortable, but easier to hide. * They can redirect the smoke from their fires to hide it with chimneys. **How can they hide the underground city and the marks of their activities ?** **I doubt they can hide it perfectly: what will betray them ?** [Answer] A perfectly hidden underground city is one that is completely self-contained in terms of food, water, air, and light. Medieval cooking will require fire of some kind so we need to work that out too. No ingress or egress is needed for a self-contained city. Since this kind of completely self-contained city isn't possible (or desirable for this story), let's walk through each need and pick some best methods to conceal. **Assumptions** * Assuming this is a [limestone cave formation](http://www.adventure-caves.com/limestone-cave.html) in a tropical or hot desert area. [![Limestone formation](https://i.stack.imgur.com/oyDPx.jpg)](https://i.stack.imgur.com/oyDPx.jpg) * There's a significant cliff nearby with passages between the galleries and the cliff face. **Air** Given that the area is already perforated with galleries and holes in rock faces getting air in and out of the galleries shouldn't be difficult. Adding many extra air shafts through relatively soft limestone shouldn't be too difficult, especially with magic. Concealing air shafts shouldn't be difficult. **Light** Darkness in a cave is absolute. No one wants to be constantly lighting lanterns for feeble flickering light so some kind of natural lighting will be needed. Natural light is free and generates no smoke. Methods for concealing air vents should work just as well for light. [![Sinkhole entrance](https://i.stack.imgur.com/TfQY0.jpg)](https://i.stack.imgur.com/TfQY0.jpg) **Ingress/Egress** Sometimes the entrances to a limestone cave system can be enormous at hundreds of feet wide. However, they can be quite small. The original entrance to [Luray Caverns](https://en.wikipedia.org/wiki/Luray_Caverns#Discovery) in Virginia, USA was too small to admit a human. Small entrances make convenient choke points and are easily hidden. Large sinkhole style entrances are also difficult to find unless someone essentially falls into them. Surrounded by dense vegetation, an intruder really will need to fall into them to find them. Large sinkhole entrances, as see in the light picture can be quite high requiring special equipment to rappel down to the cave floor. This improves defendability considerably. [![Small entrance](https://i.stack.imgur.com/Jk1rx.jpg)](https://i.stack.imgur.com/Jk1rx.jpg) **Water** Water in a limestone cave is never ever a problem as limestone caves are formed by water seepage over millions of years. Depending on where the cave citizens collect it from, it won't need any purifying or boiling. It may taste funny though. (Perhaps they will invent steam distillation to get rid of any funny taste.) No need to conceal this. **Food, Fuel and other consumables** Food is the one resource that can't be had in cave in any kind of quantity. The kinds of foods that humans prefer don't usually grow in caves (yes, mushrooms grow in the dark but mushrooms alone aren't going to sustain a population.) Nearby fields for farming will need to be concealed as well by vegetation or having the field(s) be considerably higher or lower than the surrounding terrain. You don't want the enemy commander to just look out over the surrounding area and see neat little fields that don't belong to anyone. These refugees need fuel for cooking and heating. Unless this is a cave in a tropical or hot dessert climate, the ambient air temperature in the caves will be the annual average topside temperature. If the ambient cave temperature is in the 40s or 50s (implying an outside climate that drops below freezing in the winter), the refugees may have to constantly fight [hypothermia](https://en.wikipedia.org/wiki/Hypothermia). Fires for heating will consume fuel at a prodigious rate and generate lots of smoke that will need to be managed (see next section). **Smoke** Smoke from cooking fires can be smelled from long distances. And just as predators seek prey by smell, so too will the enemy army. Smoke from fires will need to be dispersed below detection thresholds or completely captured. * Capture the smoke with magic, if the magic works that way. * Run the smoke through a multiple stage filtration system. Since there is running water nearby, force the smoke to come up through the water before being vented to the outside. Water soluble aerosols will stick in the water. It's really important to do this kind of filtration through running water. Really really important. **Sound** Given an underground city, it's possible that the enemy troops may *walk over you* on their way to someplace else. While the air and light shafts may be easily concealed, the sound of people living in the galleries will need to be carefully managed. It would be unfortunate for all other concealment measures to work perfectly until a baby starts crying and gives away the game. Long baffles or plant fiber blankets on the walls or lining the air/light shafts (where possible) might do the trick. [Answer] If your enemy is looking for you, then you can't hide. He'll find you eventually. Because of this, your first concern should be: ### Secrecy If your enemy doesn't know your city exists, he won't look for it. And if he *does* find it, it will be by accident. Your enemy will not be prepared to fight, and therefore can be eliminated quite easily by your troops, even if they're not trained soldiers, as long as they're equipped for the task. Of course, you don't have to kill the enemy. You can simply keep them imprisoned or somehow coerce them into staying with you. Naturally, this opens up the possibility of a traitor or spy hiding amongst your "immigrants", but can also make for a great introduction to your city and people. By introducing an outsider, you can explain the way your society works in a natural way. --- Of course, secrecy can not be kept indefinitely. Eventually rumors will pop up and your enemy will send out scouts. With a little bit of luck, one of those scouts will return with the Holy Grail, Excalibur, water from the Fountain of Youth, etc. With people coming and leaving, you'll need to make sure the enemy doesn't follow them back to the city, but how? ### Decoy Now that your enemy knows you're there... *somewhere*, you won't be able to cover your tracks. Well, don't do it then! Start building roads, *lots* of them. If your roads connect two or more cities, leading right in front of yours on the way, who'd think to look *there* of all places to find the rumored Hidden City? That would be too obvious! The Hidden City must be hidden somewhere in the forest to the north, it can't possibly be on the roadside. To further throw your enemies off, add fuel to the fire. Now that your city is the subject of rumors, let's create *more* rumors! * The Hidden City is inhabited by forest fairies. * Its entrance only appears during the night. * It is guarded by two ferocious humanoid wolves. And so on. Anything to make your enemy believe your city can't possibly be hidden in plain sight. If you're good at it, the rumors will spin out of control and might appear so ridiculous, that people will stop believing in them. And if people don't believe in this obviously ludicrous Hidden City, then they'll eventually stop looking for it altogether. Additionally, your citizens could easily travel to one city or another without attracting much attention. The people from City A will think they're from City B, and vice versa. The more cities your roads connect, the more difficult it will be to guess who these travelers are really from. --- This leaves us to the question: How *do* we hide that city from all the travelers and merchants who will use your roads, and how can we ensure nobody accidentally stumbles upon your city? ### Camouflage This part depends a lot on where the entrance to your city lies. If it's a cave by the mountains, you could use a boulder as a gate using your magic. A boulder in front of some rocky cliff would be as out-of-place as a tree in a forest; that is, not at all. If the entrance is a hole in the ground, you could bury it, then unbury it whenever someone needs to go in or out. Of course, the above methods assume you have mages stationed at the entrance who can open or close it fast enough for it to be practical. For a non-magical yet still practical solution you could use bushes to cover the entrance. This can be used easily without magic, but might require periodic maintenance. You wouldn't want the bush to suddenly dry up and/or die out, leaving your entrance plain for everyone to see, would you? --- Of course, you can't allow the kids to go outside. Unlike adults, they're more likely to catch attention. What are kids doing in the middle of nowhere? Are they travelling between two cities by themselves, without their parents or any other adult? Suspicious... They're also much less cautious, and might lead strangers into your city, knowingly or unknowingly. Maybe they'll mess up with your Guardian Bush, breaking off a few twigs here and there. We can't have that. The kids must learn to behave! And the animals are going to pose a problem too. If you're lucky, you'll have a pasture surrounded by mountains, and the only way to access it — aside from wandering the frozen peaks — would be through the tunnels of your city. Outsiders discovering that pasture would be very unlikely. Unfortunately, life isn't as easy as that. You'll have to keep your herd and cattle outside, in an unprotected pasture. This would inevitably lead to the question: whose cattle is this? And of course, there's the predators and the eventuality of raids. You'll have to protect them somehow, and that could easily jeopardize the hidden nature of your city. It might be best for your people to change their eating habits. No need to worry, though. You don't need pastures to raise pigs or chickens. I hope your people like bacon & eggs. --- Finally, what would be the biggest threat to your city? People. Many of them. The more people leave or enter the city at once, the greater the risk that someone will notice it. You'll have to ensure that doesn't happen. Also, if your people want to assemble, they'll have to do it within the city, or reasonably far away from the entrance. If you can, you should also try and redirect the river to flow through your city. It'd be best to avoid having people leave and enter if possible. If they can get their water directly from within the city, don't have them pointlessly exit and reenter to do it. [Answer] Listed below are your primary concerns and some suggestions about them. # Smoke Smoke is the biggest and loudest giveaway of your position. Smoke is visible from far and is a dead right clue that humans are present at exact that point. The *amount* of smoke would also hint on the size of human settlement. Since you have a complete city underground, I'm afraid the amount of smoke would be voluminous! First things first. Limit **all** fires to night time. And then too, there should be no fires lit by the public for more than 1 hour. In this one hour, they should cook, take bath (in winter), heat water for cloth-washing ... whatever. NO SMOKE FORE MORE THAN ONE HOUR AT NIGHT. PERIOD. If that one hour is late night, all the better. # Food Since your people are keeping livestock, and they livestock has to be taken out for grazing, you will have to develop a routine for that. The side your people use for taking the sheep/cattle out of the catacombs should be paved completely with water-stones and twigs. This would ensure that there are no footprints for a curious eye. [![Water Stones](https://i.stack.imgur.com/c1q6P.jpg)](https://i.stack.imgur.com/c1q6P.jpg) Furthermore, if your people hunt food to supplement their diet, do not use arrows. Lost/missed arrows stick into things and stay there prominently for a very long time. And arrows stuck in tree trunks or laying on the ground are deadsure marks of human activity. You don't want to announce your presence like that. Oh plus, I don't think you need to be notified not to use firearms. Instead, concentrate on fishing and foraging for edible roots, tubers and fruit. Oh plus, forget about growing any long term crops in your settlement. It's impossible without sunlight. # Rain Yes, considering you are living underground, if rainwater collects in your little colony, it's going to get flooded really soon. 1- Try and build a sewerage system for rainwater. If there are any caverns underneath yours, that could come in handy. Build the sewerage system in a fashion that requires least effort to keep it running. 2- Try to not let the rainwater seep into your settlement. You can do that by tightly sealing all entrances that could let water pour into your colony. Of course you cannot watertight any entrances with medieval technology, but at least minimize the water inflow as much as you can. # Sanitary In order to answer the call of nature, the citizens must go up to the surface. And after they are done, they must cover it up with a thick layer of mud. Do not let the stink announce your presence. If you limit going to surface for excretion to night times, the metabolism and biological clocks of your citizens would slowly adjust to it and they will not have any problems with it. # Time Of Activity Your citizens are going to have to live the lives of owls and bats. Sleeping in the daytime and being active in the nights. Considering normal humans (and armies) are active in the daytime, reversing your time of activity would put the chances of being discovered, to a minimum. [Answer] [Derinkuyu : Underground City](https://en.wikipedia.org/wiki/Derinkuyu_underground_city) I don't have much time to write a lengthy post, but here is a Wikipedia link to an ancient, hidden, underground city. Your question is actually a very close description to this real location. ]
[Question] [ I have a few factions in mind from various nations/cities in my world and even a couple that span the continent. I am having trouble with depth. The groups I have feel shallow and overly simplified. I am looking for a process to facilitate creating groups/organizations that are sufficiently complex and provide an interesting human interaction mini-verse. **Essentially I am looking for someone who has done this to provide guidance on their method of creating groups, with a suggested traits list or what aspects should be considered/included in any group as well as how to integrate them naturally into the world.** If you were to to write up a biography for an organization what would it include? Some example secret societies that I have looked at for reference: * Templar Order * Masons * Thieve's guild (standard fantasy fare) * Assassin's guild (think Assassins Creed) [Answer] Think about the way these organizations are created in the real world: 1. One or more people come up with an idea. 2. They rally others to their idea. 3. They create a formal mission statement around the idea. 4. They form an organization to help further the mission. 5. As the organization grows, they create a set of rules and policies that govern the members and how they are allowed to participate. 6. A hierarchy is usually created to give the organization structure (along with its rules and policies). 7. The organization continues to redefine its mission. Now, think about how these steps came about for organizations as diverse as: * League of Nations * Nazi Party * ACLU * Church of Scientology * PETA * American Medical Association Hopefully, thinking about these organizations in the context of the formative stages will help give you some insight into your fictional organizations. The depth of any organization is not just because it has a mission statement, or because it is widespread; it is because it is made up of *people* who believe in the mission of the organization, and want to help make it better. --- Now, on to creation! To create an organization, first create a character who has an idea. Now, think your way through the challenges that this character would have to overcome to foster this idea and create an organization. Don't create an organization from the top down. And don't directly base it off of an existing organization. Instead, look to that organizations founder(s), and see what happened when they put their idea in motion. For example: a thieves guild. Why create a thieves guild? Well, John Everytheif had a vision. He was tired of thieves stealing from one another. From thieves poaching on each others' territory. So, John decided to create an organization to protect this. Now that we have the who and the why, we need to explain the how. Is John a powerful and influential thief, and so he was trying to protect his own territory? Was he a lowly thief that had to go against the big guys? In John's story, you could look to drug cartels as influence. --- The point is that any deep, well thought through organization should have a story of its own. And generally, that's a story worth telling. [Answer] I generally find it important to lay out a few things for any organization, secret or not: **what are their motivations for existing, how do they interact with the rest of the world, how did they form, and how did their history help shape who they are today?** The main thing is to avoid a cookie cutter organization that isn't tied to its surroundings. If your organization could be removed from the context you want to put it in and placed somewhere else without modifying any of the background of your story, it's probably not a well though out organization. Consider the Templars, for example. On a surface level, they're an order of holy knights. However, their story is deeply ingrained into the history of the Crusades and of middle-ages Catholicism. They were created as a result of banditry and highway robbery targeting pilgrims, and gained support from Bernard of Clairvaux, which led to them being held in high esteem by both the Catholic church and European aristocracy. Their status as a popular charity during the middle ages led to great wealth and power. Wealth and power and a mission to protect pilgrims put the knights in an ideal position to safeguard the possessions of pilgrims in their fortresses, which led to their becoming a prominent bank. Another 'secret' organization worth looking at is the Sicilian Mafia in new your. Again, they have a reason for existing (to effectively commit more crime), relations with both their fellow criminal organizations as well as the countries of Italy and the United States, and a rich history which roots their origins as 'protectors' in post-feudal Sicily when the government was too weak to enforce contracts between a vastly increased number of landowners and social turmoil was leading to an increase in crime. These details give the mafia a reason for existing, as well as contextualizing why they ally with which other groups. It's also important to note that, for both the Templars and the Sicilian Mafia, their existence was strongly tied to the historical context in which they formed. They did not arise from the ether at some point in history at the behest of a powerful individual, but rather were reactions to the social conditions of their day and age. These origins give them a reason for existing, though their origins don't fully define them as their interactions with other groups through their history constantly change them, or, in the case of the Templars, destroy them. [Answer] A couple of questions when creating groups: * **Their goals** : Why do they exist ? They serve an ideal, a religion, another organization. They exist to control the commerce (Thieve guild), to protect the frontier and avoid chaos (military orders). * **Membership: Who can join**, how do we join : is there a ritual of passage?, responsibilities of the members, do they have special rules? do they have a proof of membership (object, handshake), do they receive something for their membership (equipment as in Assassin's Creed), how do they behave among each other vs the outside world, do they have rituals/holidays/prayers ... Do they have secrets?, Is there a sanctions for disrespecting the organization/failing an important task? Can a member loose it's membership ? without dying ? * **Structure of the organization:** the have only one base, the organization exists in different area throughout the region, the organization is established in different countries. Is there a central authority in relation with the local branch or are they all relatively autonomous? If there is a centralized organization: how does it work? How are decisions taken and by whom ? who leads the organization and the local branches? How are leaders chosen? * **How are they financed ?** It could be the patronage form the local lord , the aristocracy, money taken as a tax form the population and redistributed secretly. It could be the financial support form the clergy or another third party organization that is not secret. A thieve guild might set a monopoly on every shops in the city and they collect tax, like the mafia if you want : a protection tax, or a pay or we will burn your house tax. Most military orders were granted holdings where they could tax the population to finance their military efforts. Many religious order also produce goods by themselves. * **Interactions with their surroundings:** An organization could have a public face and a private one, each with different objectives. A powerful military order like the Templar order as it is described in Assassin's Creed is that kind of two faces organization. the organization might become perverted or corrupted over time and the goals have changed. [Answer] Very often secret societies come about from a fairly specific set of circumstances, roughly along these lines: * **A Parent Organisation** - in many cases they arise out of religions, but they could also rise out of craft guilds, armies ( or army regiments ) or even government departments. * **Someone with a vision** Secret societies tend to have a fairly simple vision or goal that they seek to perpetuate or carry out. Often it is to take the teachings of the parent organisation further, but occasionally it is to subvert it or otherwise change it to their own ends. This vision usually starts either with a single charismatic individual or with a small group who share the same ideals. * **Secrecy versus popularity** There is a continuum of secrecy and popularity- once everyone knows about an organisation they can hardly claim to be secret. If they are too closely guarded a secret then unless the members are very influential or the goal is very easily achieved they are unlikely to be able to recruit enough members to endure and probably are more a plot than an actual secret society. This also relates to membership and recruitment- how you ensure that you only get people who are truly committed and avoid being infiltrated by those who oppose the society's goals and how you ensure the society's goals endure until they are achieved are questions that the founders of the society need to answer. * **Keeping existence hidden** - People love a secret, they will actively seek them out and puzzle over them ( for a great take on this and how people think of secret societies in general you could read *Foucaults Pendulum* - but it is heavy going ) so the biggest secret your society needs to hide if they really want to stay in the shadows is that there is a secret at all. [Answer] [This article](https://roleplayingtips.com/rptn/rpt695-crossing-swords-factions-build-quick-guilds-kingdom/ "This article") is more geared towards role-playing games, but it can be useful for getting a simple outline started when one encounters a writing block or needs a simple history of a guild. Basically, you take a deck of cards, and the article has tables that match the card draws. This covers a simple creation motivation to general events in the guild's history. Guilds made through this have a basic 'alignment' of if they support the government, if they are rich or poor, if they are large or small, and a few things they are doing right now. You can extrapolate a great deal from these beginning details if you want too. For example, if a guild is small and doesn't support the government, you can extrapolate that it is secretive and persecuted by governmental agents. This is useful tool for getting a quick, basic framework of a guild. ]
[Question] [ When designing a world it is convenient to decide how places will be named: Elements like the continents and the oceans. However, it is likely that the different cultures of the world will not agree on a common name for these places. Some might not even know there is an ocean or maybe they just don't care and will simply use the name already given to that place by others. **An example of modern naming [dispute](http://en.wikipedia.org/wiki/Sea_of_Japan_naming_dispute).** On Earth, a lot of places have the names they have now because the Europeans established the conventions. On the other hand, I know that the norms do not apply everywhere. For example, China is Zhōngguó (中国) in mandarin Chinese. It's not a translation of China, the meaning is very different. China comes from the Qin dynasty that established contact with the Europeans a long time ago. People in China will probably not use China to talk about their country unless they speak with foreigners. **How do we solve this issue in world-building?** In real life, we would have an atlas in our own language and places would be named accordingly. Original names of other languages are harder to understand for those that do not speak the language. * Sometimes, the names are written using the same phonetic but adapted for the language : Beijing becomes Peking * Sometimes the name can simply be translated: United States, États-Unis (French) * Other times, it's completely different like with China When making a map and designing a world, we can't have multiple names for each place, it's far too confusing. Maybe they could have multiple names but we got to have a common name at least for designing purposes. * We could have a culture dominating the world that imposed the names. * We could only use the local names for each place but what do we do when we have multiple names as for the oceans? * We could build the world using only one culture point of view? (even if that culture is not dominating the world) [Answer] There are a couple ways to decide what to name elements of a map: ## Culture Map is From When a map is from a specific culture, the names on the map will be the names that culture uses. So in your case, if the map was a Chinese map, it would show all the names the way the Chinese say them. This method works best if all the protagonists are from one culture, then the map can be from that culture. When the protagonists travel, the author has to translate names of places into the language of the map. Or, the author could write a glossary in the back, translating place names in various languages. ## Names from the Dominate Culture You could make all the names on the map from the dominate culture. In the European vs. Chinese example above, this method would result in all the names being European. This is usually a good method, as the dominate culture's names are often more widespread than a specific culture's names. For example, even if the protagonist was from China, he might go to Thailand. People in Thailand wouldn't know the Chinese names, but they would know the European names (mostly). ## Use Local Names with a Glossary Instead of using only one language for the map, instead use multiple languages. Each place name is the local language. For places with conflicting names, such as oceans, use the dominate culture's names or the name's of the protagonist's culture. A good extension to this method would be a glossary with the map, that translated place names on the map into the dominate culture's names or the protagonist's culture's names. [Answer] This problem isn't limited to places; it extends to every named facet of your world. Especially in worlds without internet and standardized encyclopedias, everything will have lots of different names. This is a little confusing, like real life. I wrote a [short article](http://exnihilonihilfit.com/2014/02/03/relativity-reality/) on this topic a few months back; my solution is to use **meta-names** so that I could consistently refer to things in my world by the same name when I'm writing canon articles. Meta-naming is loosely based on the idea of having **universal/scientific names** (e.g. *Homo Sapiens*) to avoid the confusion of having different names for things in every language. For example, I'd meta-name a city "Kallapolis," because I like to mash up Greek roots (you could just use your native tongue for meta-names, in which case it'd be "Beautiful City"). In my "Kallapolis" article, I can list all the in-world (conlang) names of the city - the name the current rulers call it, the name the previous rulers called it, the nicknames the residents call it, and all its names in different languages. (Meta-names are also good placeholders for when I'm writing fiction but I haven't worked out the conlang yet.) Meta-names are for **organization** during the worldbuilding process. Once you're writing fiction that takes place in your world, it makes sense to let your characters call it by the name of their culture, in their own language. If there are multiple characters referring to it by different names, your characters should be confused before your readers, and you can clear that up with dialogue. Same goes for maps - if you're making a meta-map use your meta-names, but if the map was drawn by a fictional character then just use the names of their language and culture. There are many possible approaches here, but this is what works for me. [Answer] Different names exist for a reason, or various reasons, as you have listed. The differing phonologies of languages are the technical aspect, but there's a deep political and historical divide behind the dispute. **Does your world exist to be a backdrop to a story?** If it does, then the story most likely has a plot and a protagonist. These two determine what belongs on the map. If your character is a member of a powerful, conquering culture, and the plot involves his fighting against an uprising at a remote province, then the map would show the foreign/imposed exonym. Conversely, if your character is powerless, then the disparity between the names he uses and the names on the maps is very important. The short version is, you can **use a cross-cultural trade language** that's known to most cultures in the subset of the world in which you're working. The language may be **descended from a historical one** that's under little dispute, and it doesn't have to be a trade language, either: academic, military, or (very often) mystical concerns can also determine a *lingua franca*. As centuries of European scholars corresponded in Latin and Greek. The amount of detail you invest in making your world multilingual depends on what you choose to focus on. If your worldbuilding contains lots of information about borders, empires, cross-cultural affairs and political or diplomatic intrigue, then it's worth the effort to make a nod towards having multiple names, even if it's a minor one. If you deal primarily with metaphysical or esoteric subject matter, then you can probably get away with one language, or using just a few words in the "mystical tongue" for spells or other arcane artifacts. This is pretty common, and readers largely accept it. You also have other possibilities. It's not uncommon for the written language to have **several spoken dialects**, if they are used across a very large area. Chinese and Arabic are both languages with a huge distribution where different regional "dialects" are so different they could be termed different languages, but letters, academic texts, tax records and *maps* can still be read by anyone with an education. As a side-note, in my current worldbuilding project I used an approach similar to this. It's worth noting that my map covers a fairly small area, though. If your worldbuilding is more ambitious (most are) then you might find my method constraining. Most of all, it depends on **what you're interested in**. ]
[Question] [ I got many little trading posts all over my worlds and orbiting around them. Everyone can trade in there, nice guys as well as scum of all kind. The trading posts are rich places. **How could a system be established that would make the posts safer against the scum traders and bandits/pirates? Or why would no pirate or bandit try to raid the posts? Basically how could such trading posts be a safe place to trade for all traders?** There is a law force but they are very corrupt. There are also gun towers and gunners paid by the trading posts, but they alone would not be able to hold against a full scaled raid - they're more for shoplifters and lower-level scum. [Answer] Traditionally pirates are cowards. They go for the easiest prey, for the most gain. In the few cases of where you hear of "daring" pirate attacks, it is because the pirates have a leader who either scares them more than the prospect of do a dangerous attack, or the leader convinces them that the loot will be worth the risk. Usually the former. But these leaders are few and far between, generally pirates parties are going to be unstable, criminals don't trust each other. So the goal of a trading post would be to try and keep themselves stronger than other closer targets. There are multiple ways they could do this. 1. Hide wealth. This would work because it would make them look less worthwhile than nearby stations. Unfortunately this would be hard to do, trading generally means wealth after all, and it could also reduce trade. 2. Sabotage other nearby trading posts. This would be an interesting, and somewhat risky technique. If a station could make other nearby stations weaker, pirates would be more likely to attack the other stations. 3. Rumors. If a trading post could manage to start a convincing rumor that it had some secret defense that will blow pirates out of the sky, then pirates may possible be tricked into believing it. Probably the best way to do this would be to hire an unfortunate pirate (who had got his ship blown up near the trading post), to spread the tale. 4. Form a federation. Have several nearby trading posts from a collective army (of mercenaries). If a pirate should attack any of the stations, the entire army goes after the pirates. The army will also come from all the stations, and with the combined wealth of several station, would be quite powerful. This would be a major disincentive for pirates to attack. The disadvantage of this is that you pull yourself up to equal strong as nearby stations, which means you are all equal hard for pirates to loot. That means the pirates may just decide to have a go at the station, because they have no better chance anywhere else nearby. Now, another interesting option would be that the pirates actually *own* the posts. So each pirate group will try to protect their post at all costs. After all it is the source of their wealth. Pirates who try and attack the post will know that their post will likely be counterattacked. Whatever authorities exist in the galaxy would probably be bribed to ignore pirate going-ons. Trade posts could also have a group of pirates that associate with the post. These pirates would always trade at the post, as well as protect the post. In return they would get cheaper prices and possibly a share of profits. And local authorities would turn a blind-eye to anything the pirates did that, well "bent" the rules a little. [Answer] The thing about being a pirate is that you have a job to do, that being pirating stuff. There are two things that a successful pirate needs: * A place where marks are going with goods that could be successfully pirated. * A place where pirates can sell said goods without too many questions asked. So for pirates to raid trading posts, they risk biting the hand that feeds them - I mean obviously we are dealing with scummy space bandits here who are out to steal everything that they can, but the smart pirate is going to want to have a sustainable business model that offers them the most possible profit for the least risk. That means that you pick up on shipping, but you probably leave trading ports well alone because you actually want to have agents in them telling you about shipments coming and going and helping you to fence goods that you have purloined. If you turn an entire station over, then you have a good chance of harming your own people or reducing a potential source of revenue. The consequence is that pirates and shadow economy traders are going to need those trading posts as much as anybody else and they are going to benefit from a certain status-quo where no trading post gets too powerful or able to make stronger demands but in the case of an outside raid on a planet's periphery stations, you are likely to see an unlikely alliance of local criminals, local law makers and the stations themselves banding together to protect their local power base. Criminal organisations' interests do not necessarily stand against everyone else's - look at the role of the Mafia in WW2 - and competent criminals, the ones sufficiently resourceful to have control of ships capable of causing serious trouble to a trading post, are likely to be rational about matters of business and income. Edit: It occurs to me on rereading this that one of the important things for your trading posts is that they don't need to be objectively tough, they need to be *relatively high risk* targets. So if a potential raider looks at your trading post and the other trading posts and the traffic coming into and going out of the trading posts, they need to see that a raid on your trading post is going to be a bigger risk than a raid on others. It is less about being a *hard target* and more about being *less of an easy target.* [Answer] Simple suggestions: 1. Bounties as a deterrent. 2. Private security/military. 3. Paying protection money to local pirate group. 4. Local militia. 5. Societal viewpoints. Since scum use these places as trade, attacking them might be counter productive - at least in the eyes of some of the older, wiser and meaner 'scum'. 6. Easier targets elsewhere. [Answer] Pirate ships probably don't *want* to destroy the only place where they can get wealthy. So, have **one** trading station for every planet. Alternatively, you could have an announcement on the PA system like "Alert! Alert incoming offensive ships, please evacuate, and if possible defend the station.", because it is in the interests of the peaceful (as well as the scum) traders to defend the trading post. Another idea is that maybe normal spaceships can only go from one trading station to another, and not land. If you have special ships that can land more efficiently, they don't need to carry an extra ton or two of the equipment to so whatever you do to get to another planet. If you are going from planet to planet, you don't really need to carry an extra few tons of fuel, or a parachute, not to mention how dangerous it is to carry humans (pilots) up and down a gravity well. [Answer] If the trading post itself is relatively cheap compared to the goods it contains, then a simple, "death before dishonor" mindset will do. If the pirates take the goods, they're lost anyway, so just make sure to always destroy them before the pirates can get their grubby mitts on them. Once it becomes known that prospective pirates not only must fly in under the station's guns, but also have to get out of the blast radius before the bombs go off, the risk/reward ratio becomes too unfavorable to bother with frontal assaults and thefts will be focused more around fraud or stealth. [Answer] ## **The trading posts are just delivery endpoints, not storage locations.** Instead of a warehouse filled with goods, a trading post is a combination of a high-powered railgun that launches stealth-shielded shipping crates around the star system, and the inverse -- a magnetic funnel catcher. Even in a star system, space is really big. Out in the dark between planets and stuff, it's nearly impossible to find space-amazon's hidden delivery network. So traders drop off their products to sell, and it all gets immediately shot off in seemingly random directions based on a patented secret algorithm. Then folks can use a kiosk to manage their credit or place orders. Due to the company's distributed shipping system, top-secret methods, and crates flying at relativistic speeds, traders will wait at most a few hours for deliveries. Just enough time for a shower and a visit to the saloon or arcade. If you're on time to the funnel catcher, you'll make a quick exit less than a minute after your purchases get thrown into your cargo bay. But keep an eye out for foolish slowpokes asleep at the bar; you don't want to be around when pirates get too tempted by a huge score floating at the dock. So then, trading posts are safe because **nothing sticks around long enough to get stolen**. Usually. [Answer] In the Caribbean, pirates had small, fast ships. The only perennial deterrents were shore batteries (most pirates wouldn't go near them), and more importantly, navy ships. Navy ships were far stronger but also often faster than pirates, allowing them to eliminate piracy in an area. Like in your scenario, local governors and garrisons were often corrupt, but the Royal Navy was not; where they showed up, piracy ceased (at least until they left). [Answer] **Weapons check** They were not always trading posts. They are ancient strongpoints and they can be locked down. Persons entering a trading post go thru a checkpoint where they leave their weapons. Persons thinking they are going to shoot their way through the checkpoint find themselves in an empty metal hallway with their guns, where they stay until they become more reasonable. Persons divested of weapons who think they will rob a checkpoint using only space kungfu skills will fight kungfu cyborgs with great awesomeness so that still might work. Persons parking warships outside the trading post and threatening from outside will learn why these were called strongpoints. Posts are no longer heavily armed, but are still armored to resist the terrible weapons of a previous age. Weapons now available are no match. The pirates can waste their energy if they want. Clarification: *Most* posts are no longer heavily armed. Or at least they have not tried those weapons in a long time. Some places still have stuff no-one is sure how to use. Except for that one kung fu cyborg because he is 700 years old. Yes, this anime pretty much writes itself. [Answer] # The trading posts band together to hire mercenaries to kill anyone who raids them and their families. From history, there are generally two ways to handle pirates. One way is to pay tribute. This often results in them attacking you to demand more tribute. The other, more successful way is to murder all of them. Ships are extremely expensive purchases. It can be extraordinarily profitable pirating, but you need to spend a lot to make a ship. It's also hard to disguise a ship, short of rebuilding it- distinctive isotope signatures and marks of how it was built and engine signatures mean you can generally tell where it was from. The trading posts have a group agreement to kill anyone who funds pirates. Mercenaries are hired and the bases and worlds that supported the pirates get bombarded with nuclear blasts. Any shipyards or complicated technology are smashed to rubble, and it can take centuries to rebuilt the tech base of a world back up. Most worlds are terrified of this happening to them, and pirate crews will mutiny if pressed to attack a trading post, knowing that their loved ones will die in a nuclear flame if they do. [Answer] Privateering? In the early days of Caribbean piracy, most pirates were British privateers with letters of marque raiding Spanish ships. One consequence of the letter of marque system is that when the nations were at peace, it would become illegal to conduct piracy. This gives you a good excuse to 'switch' piracy on and (almost) off in any area; have the nation of pirates strike peace/declare war on the nation that runs the trading posts. Of course, a few desperate figures will keep pirating anyway... [Answer] Well, it depends on just how smart your pirates are, and what technology they have at their disposal. You haven't specified either. I'll take an average intelligence, but due to the 'spaceships' tag I'll assume these are ultra-modern level pirates. The question is simple: You have numerous really rich places where a absolute boatload of money needs to be kept safe. Some groups of people (pirates) want to get said money. They are crazy enough that anything we do does not prevent attack. Our job is to find a way to protect it. The closest thing I can think of in our current world is Las Vegas. Of course, it's casinos and not trading posts, but it is still a large number of businesses, each with a lot of money that needs to be able to be accessed semi-regularly. And naturally, they have some of the greatest security systems. Researching modern casino security would be great option for you trying to figure out this. ]
[Question] [ [Prototaxites](https://en.wikipedia.org/wiki/Prototaxites). Giant, finger-shaped mushrooms. [![Painting by Mary Parrish, National Museum of Natural History.](https://i.stack.imgur.com/TC2ln.jpg)](https://i.stack.imgur.com/TC2ln.jpg) [Painting by Mary Parrish, National Museum of Natural History.](http://www-news.uchicago.edu/releases/07/070423.fungus.shtml) These monsters existed before trees did, and while there are a few theories on whether they *actually* existed as depicted above, for the sake of the fact that I'm going with an alien planet, I'm going to assume that's how they were. What I'm wondering is **could a fungoid-like in such a configuration be used instead of wood?** IE, could you dry it, cut it into planks, build a boat out of those planks, build a house, etc. For *ease of answering* presume it follows terrestrial biology as much as practical, and has been given conditions in which it could grow. [Answer] This is the closest thing I could find to fungi being used in a way similar to wood, [Mushroom furniture](https://blogs.scientificamerican.com/guest-blog/making-furniture-from-fungi/). > > Ross begins with a carbon-based agricultural byproduct, like cornhusks > or sawdust, and adds a bit of mycelium tissue. The culture comes from > Ganoderma lucidum, a mushroom that forms chestnut-colored saucers on > surfaces it colonizes. Most importantly, it grows at room temperature, > ideal for a lab aiming to keep energy costs low. > > > The mycelium feeds on the sawdust over a couple of weeks and forms a > vast web of fibers. Ross then transfers the growing structure to a > mold, and the fibers grow to fill the form of the container, be it > brick- or chair-shaped. Next, Ross pops the structure into an oven to > denature proteins and kill the fungus. > > > Its strength ranges from cork to balsa wood depending on various factors, and when making furniture, the inventor uses wooden legs for support. So I don't think earth fungi would be very good as a replacement for wood. However the cells of fungi are made of chitin which can have some strength if made thick enough. For the exo-fungi, instead of having the cells creating thin fibrous strands, have the cells lock together like bricks. To make it a bit different from wood, have them being flexible and leathery while alive or recently cut, but when properly dried they stiffen up and act more like wood. This would let people or aliens bend and twist them into many different shapes before drying to give them an organic, almost grown look to them. [Answer] Fossil mushrooms are rarities. Mushrooms are the fungal equivalent of flowers - spongy, ephemeral, disposable bodies generated to serve a reproductive need. You could not use mushrooms for wood. The prototaxites were not mushrooms. They were large and substantial. I deduce this from the presence of growth rings in the fossil prototaxites. [![growth rings in fossil prototaxite](https://i.stack.imgur.com/kSaIi.jpg)](https://i.stack.imgur.com/kSaIi.jpg) <https://www.researchgate.net/figure/Transversely-sectioned-Prototaxites-fossil-This-overview-image-originating-from-a_fig1_51174561> The presence of rings means this structure endured shifts in growing conditions over time. This thing was there for many seasons. On earth, that means it weathered storms and wind: no small feat for an upright thing this size. There is an analogous modern fungus: the [bracket fungus](http://www2.palomar.edu/users/warmstrong/bracfung.htm) aka "shelf fungus". [![shelf fungus](https://i.stack.imgur.com/CTPPJ.jpg)](https://i.stack.imgur.com/CTPPJ.jpg) The shelf is also a spore-making body but a permanent one, and it also can persist many seasons, laying down growth rings with the seasons. Bracket fungi are as tough as wood. <https://herbarium.usu.edu/fun-with-fungi/shelf-fungi> > > Woody shelves may be several years old. They add a new layer of spore > tissue every growing season. The old layer is covered by the new one. > These layers look like growth rings in a tree. One author reported > counting 37 rings. Ten layers may mean the shelf is 10 years-old if > there is only one growing season (spring). If there are two growing > seasons per year (spring and fall), it may only be 5 years-old. > > > One of the largest shelves weighs 300 pounds… > > > Woody shelves are impossible to break with your hands and difficult to > cut. This toughness results from the kinds of hyphae (filaments) that > are used to construct the shelf. Easily crushed mushrooms are made of > thin-walled hyphae. Some of the hyphae in woody shelves are > thick-walled and the hyphae are interwoven making them tougher. They > resist tearing or splitting because there are no planes to split along > in the tissue. > > > A bracket fungus large enough could be used for wood. The medium to small ones are used to make real shelves and durable beads. **It is reasonable to assume the prototaxites were of a composition similar to modern bracket fungi and so suitable for use as a wood equivalent.** [Answer] Earth fungi are made of chitin, which is plenty durable enough to build housing and furniture out of, although it will not be as strong as actual wood, and you will not be able to build tools out of it, although you could say they are made of a denser chitin than earth fungi. Of course as aliens fungi-like things and not actually earth fungi you could just say they are actually made of cellulose instead of chitin (or both), there is no reason they have to be made of chitin only, it is a fluke of evolution. Biologically there is not much difference between the two materials as far as production goes so you would be fine having them made of cellulose (wood). Nearly anything organic will burn so it is fine as fuel. However it will burn like a light wood not a dense one. the real trick is they will not be all that common since they are not primary producers they need to get the energy to grow from something else, like dead plants, so using them for fuel will be tricky just logistically. [Answer] If we are talking about creatures similar to those of our world developing and evolving for ages in other planets, there is nothing keeping those fungus from using hard materials for a skeletal support structure. On Earth fungi have chitin, as has already been described on the other answers. An alien fungi might also use bone (why not?), cartilage, glass [(some sponges have glass structures)](https://en.wikipedia.org/wiki/Hexactinellid), cellullose [(which is chemically very similar to chitin)](https://en.wikipedia.org/wiki/Chitin#Chemistry,_physical_properties_and_biological_function), iron-mineralised scales [(such as this snail)](https://en.wikipedia.org/wiki/Scaly-foot_gastropod), or a combination of those. By combining every form that has been tested and tried by nature in our own world, the alien fungus could be harder than anything on Earth, and grow larger than sequoia. ]
[Question] [ If two species with no previous knowledge of one another, and no knowledge of each other's environments (say they're on the other side of a wormhole through which they can shoot a radio signal), what system of measurement would they use to communicate? Someone once suggested to me that the period length of a hydrogen atom, which they said was 21 cm, would make a good universal measurement standard for beings with our basic scale. Not knowing any better, I accept their assertion. Binary seems like a good numeric base, with useful "higher" numeric bases of base 8 and base 16 being easy to agree on. How about mass, though? And time? What could they communicate those ideas with to establish them? **Update:** One answer suggests the [**International System of Units**](https://en.wikipedia.org/wiki/International_System_of_Units). Skimming through the Wikipedia article, it provides measurements such as "metre (current): the distance traveled by light in vacuum in 1/299792458 second." How would we communicate the 299792458 denominator for a second? For that matter, how do we communicate a "second"? Its definition is even more obscure. I'm looking for a more straightforward unit of measurement, such as the aforementioned length of the period of a hydrogen atom. Also, the units of measurement should be useful at scales that are useful to our physical form and attention span. I'm presuming that any alien race we'd have much in common with would have physical attributes (scale, time sense) similar to ours. We may learn a lot from sentient quasars, but we would seem horribly impatient to them given that our lifespans are so short. **Clarification:** Based on comments and answers that have been provided, I think I was unclear with my question. Perhaps I should re-frame the question this way: What units of measurement could we concoct that would be useful to us in our day-to-day lives that are based on things occurring in nature and are observable no matter where you are? For some reining in of possibilities, I'll limit the "where" to our galaxy and relative acceleration. The suggested unit of length I posited (which turns out to be the [hydrogen line](http://en.wikipedia.org/wiki/Hydrogen_line)) is useful at our scale. If every length measurement we used on Earth was based on this, we would be no worse off than we are using meters or feet. We could call it the *hyl*, craft a symbol for it, and start measuring things. If aliens ever call, and ask what unit of measurement we use, we could say, "Oh, it's this, which you should be able to measure on your end and understand what we mean when we say *hyl*". The bit about communicating with aliens is really just a different way to say "how do you determine it no matter where you are"? At least that's the way I meant it; perhaps that's a different question. So, again, what other measurements could we use that are useful to us at our scale? Things that are about the size of a pound or a kilogram, a minute or an hour... or... [Answer] The [fundamental physical constants of our Universe](http://en.wikipedia.org/wiki/Physical_constant#Table_of_universal_constants) * $ c $ speed of light in a vacuum - units $ \frac {distance}{time} $ * $ G $ Universal gravitation constant - units - $ \frac {distance^3}{mass \times time^2} $ * $ ℏ $ Reduced Planck Constant - units - $ energy \times time = \frac {mass \times distance^2}{time^2} $ You can manipulate these Universal constants to develop fundamental, [Natural Units](http://en.wikipedia.org/wiki/Natural_units#Systems_of_natural_units) based upon the physics of our Universe and not based upon any reference object. Planck Length $$ L\_{Planck} = \sqrt{\frac{G \* ℏ}{c^3}} $$ Planck Time $$ T\_{Planck} = \sqrt{\frac{G \* ℏ}{c^5}} $$ Planck mass $$ m\_{Planck} = \sqrt{\frac{ℏ \* c}{G}} $$ > > Planck units are a system of natural units that is not defined in > terms of properties of any prototype, physical object, or even > elementary particle. They only refer to the basic structure of the > laws of physics: c and G are part of the structure of spacetime in > general relativity, and ℏ captures the relationship between energy and > frequency which is at the foundation of quantum mechanics. This makes > Planck units particularly useful and common in theories of quantum > gravity, including string theory. > > > There are many more Natural Units (and Universal Constants) at the link and we'd have to work through derivations for electric charge, magnetic fields, etc. [Answer] Actually the [International System (SI)](http://en.wikipedia.org/wiki/International_System_of_Units) that most of the world already uses is designed in such a way that it would be simple to share with our alien friends. The SI system has been systematically redefining it's basic units so that it is possible to recreate the units from the definitions themselves. Though this was not done to share with aliens, it is exactly what you need. --- The Wikipedia page lists the history of the definitions. Of the 7 base units, only the mole and kilogram rely upon things not completely reproducible across the wormhole, and this will no doubt be changed in the near future by defining the mole as a simple quantity and mass in terms of a mole of a given isotope of silicon (most likely). There are lower-tech approximates for many of the base units that could be determined in a well equipped high-school science labs. --- Also note that a lot of careful thought has already gone into the process of redefining the SI units. They must be unambiguous, reproducible from the definitions and measures that can be made in the laboratory, and very accurately measured. [Answer] If you want units that don't need big numbers in definition or in everyday measurements, you can use, together with **your *hyl* ([21.10611405413 cm](https://en.wikipedia.org/wiki/Hydrogen_line))**: * **mean lifetime of neutron: [880.3 ± 1.1 s](http://pdg8.lbl.gov/rpp2014v1/pdgLive/Particle.action?node=S017) or 14 min 40.3 ± 1.1 s** — not very precisely known. * **mass of cubic hyl of liquid water at triple point**. [This page](http://www.peacesoftware.de/einigewerte/wasser_dampf_e.html) calculates for the triple point ([0.01 °C, 611.73 Pa](https://en.wikipedia.org/wiki/Properties_of_water#Triple_point)) density 999.79374544304 kg/m³. Temperature is from definition, but pressure precision probably (I'm really not sure) limits result to five significant digits. This gives **9.4002 kg**. * for electric units, **absolute potential** ([the difference in electronic energy between a point inside the metal (Fermi level) of an electrode and a point outside the electrolyte in which the electrode is submerged (an electron at rest in vacuum](https://en.wikipedia.org/wiki/Absolute_electrode_potential)) **of standard hydrogen electrode** (2H+(aq) + 2e− → H2(g) on platinum electrode): **[4.44 ± 0.02 V](http://old.iupac.org/goldbook/S05917.pdf), but note:** at 25 °C, for triple point I can't find value Actually, I suppose that SI unit definitions were chosen to use precisely measured values and even gravitation constant, necessary for natural units, is much better known than neutron lifetime. Big numbers are just big numbers and not so hard to understand and barring a big number, definition of the second (the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom) is analogous to definition of the *hyl* (the length of the wave of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the hydrogen-1 atom). [Answer] What do we have in common with the aliens? Integers (ie. we can both count and send numbers). Universal constants. Atoms. That's plenty, and it's already being taken advantage of here on Earth. Alien communication will benefit greatly from the terrestrial efforts of international standards to define units of measurements in absolute terms. Mass can be sent as the number of atoms of a stable, common isotope. The Kilogram is currently being redefined as ["the mass equal to that of 1000⁄12 x 6.02214×10^23 atoms of Carbon 12."](https://en.wikipedia.org/wiki/Kilogram#Carbon-12). The mass of a fixed number of atoms is universal, it can reproduced by aliens. [This video about the new Kilogram standard](https://www.youtube.com/watch?v=ZMByI4s-D-Y) explains how you'd produce such a thing and why that's plenty accurate, more accurate than the standard kilogram. From there, plus the speed of light, you can derive energy via `E = mc^2`. Time can be transmitted the same way we measure it now, [the number of oscillations of a chosen atomic particle](https://en.wikipedia.org/wiki/Time_in_physics#The_unit_of_measurement_of_time:_the_second). > > The duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. > > > Once you have time, you can define length as how far light travels in a given time. Electric charge is simply [the charge of an electron or proton](https://en.wikipedia.org/wiki/Elementary_charge). For temperature, the [Cosmic Background Radiation](https://en.wikipedia.org/wiki/Cosmic_background_radiation) can be used as a first order approximation. However, our current definition for the Kelvin works just fine. > > 1⁄273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01 °C or 32.018 °F). In other words, it is defined such that the triple point of water is exactly 273.16 K. > > > There is only one [triple point of water](https://en.wikipedia.org/wiki/Triple_point#Triple_points_of_water) and it is at a certain temperature and pressure (you get pressure in the bargain). This neatly gets around the problem of using boiling or freezing as the benchmark as they are not fixed points, but change with both temperature and pressure. --- This is all great to start with, but mass, length and time are all relative to your local spacetime warping. That is: gravity. These can be measured even with the slight gravitational anomalies on Earth, atomic clocks around the world fall out of sync. Fortunately, the differences in measurement from one planet to another will be very, very small. Ignoring spacetime warping gets you a very, very long way and is good enough for most science. [Answer] I guess you're assuming that we are otherwise able to communicate, learn each other's languages, etc. Otherwise any attempt to establish common units of measurements will get bogged down in basic comprehension. Something like a kilogram would be almost impossible to communicate. The definition of a kilogram is that it is the mass of a certain block of platinum at the national bureau of standards in Paris. If the aliens can't visit Paris to weight it, they're out of luck. You could define mass in terms of the mass of a specific atoms, say Hydrogen. To scale it to something convenient for creatures our size, say the mass of 10^24 atoms of hydrogen or whatever convenient number. For time I'd say to take the half life of some naturally occurring radioactive isotope. Distance could then be the distance that light travels in a specified amount of time -- assuming we've got time worked out from the previous step. Energy could be the amount of energy released by a specific chemical reaction. Or a nuclear reaction, I suppose. Let's see, once you have time, mass, distance, and energy, I think most other units can be derived from those. [Answer] I came across this question having sought the same exact thing! I felt that measurements based on atomic weights and distances would be difficult to convey, and suffered from uncertainty in any event. One constant I would work with is that of gravity; as one of the four fundamental forces, it can be assumed to be understood by any spacefaring race. When considering any solid round body (for example, the Earth), if that body was thought of as having a small hole through its center to the other side, and a small mass (for example, a marble) through that hole, it would accelerate more and more, then pass the center and slowly come to a stop as it would reach the other side. (This, of course, assumes operation in a vacuum and ignores geothermal effects.) The calculation is simple, and both races could agree that 1 pass would be equal to 1 unit of time. On Earth, this traversal is 45 minutes... and no matter what size the body may be, that traversal will take the same length of time. --- *Ed. Note: This is not remotely true, but could still be a worldbuilding suggestion provided that the question doesn't depend on actual science.* ]
[Question] [ Real x-ray vision, the ability to (at least) detect X-rays as a 'visible' light (or any other detection system) seems it would be very problematic. X-Rays are a high energy form of electromagnetic radiation and are very damaging to living tissue (at least on Earth). So developing a sensor to detect it would suggest that the evolutionary process felt the need to detect them, maybe as a way to avoid them? So what would cause a species to be able to detect x-rays and still live in a viable environment that wouldn't cook them to death? Or might they have developed (like Superman) an X-ray transmitter for communication? Or a natural biological weapon? [Answer] X-Rays are not death rays. Yes, they are (or at least can be) high-energy radiation, but at low levels they can still be detectable without "cooking" anyone or anything. In fact, at this very moment (unless you're sitting your lead-lined radiation shelter), you are being bathed in X-Rays that are the result of the background cosmic radiation interacting with our atmosphere and generating a slew of secondary radiation. It's of course heavier in the upper layers of the atmosphere; so much so, in fact, that it's actually [a concern for airline crews](http://www.hps.org/publicinformation/ate/faqs/commercialflights.html) and very frequent travelers -- though that's mostly from the other types generated rather than the X-Rays per se. Back to the point: Why would any creature evolve the ability to detect X-Rays? Putting aside that evolution isn't some intelligent entity that sits on a mountain pondering, "What should I evolve next?", as anyone who has been to the dentist or broken (or suspected they broke) a bone, X-Rays are good at passing through things. So one advantage a creature with "X-Ray vision" would have could be the ability to better see other creatures (or hazards) hiding in foliage, for example; they'd be able to see a skeleton behind that cluster of leaves over there. Another advantage -- though of more utility to an intelligent creature -- would be to be able to see and diagnose skeletal problems, such as broken bones, without the need for complex machinery. This could allow a herd to more readily identify and care for an injured individual, or a predator to more easily spot the weakling in the herd and go for them. (Consider e.g. a hairline fracture, which you could walk on with not much more than a limp just fine; suddenly have to start running and zig-zagging to avoid a predator, however, and your own evasions could snap the bone the rest of the way, crippling you at the worst possible moment!) And, of course, it would give any creature that could see them a big bright practically-neon warning sign to stay away from any very high-level sources that could be dangerous to even be in the general vicinity of. That said, however, the background radiation isn't strong enough to get photographic quality images of bones. Not in our environment, at least. There could still be some of the same benefits, but far from the dramatic representations of Superman's power (which, more often than not, is "see-through vision", not really "X-Ray vision" /soapbox). There are, however, other types of radiation, other particles, that could have similar results for a creature capable of detecting them, yet don't pose a health hazard by simply being present at the necessary levels to be useful. On the other hand, a creature in an environment where X-Rays per se are present at a high enough level to be truly useful would no doubt have evolved in a way to be resistant to, if not immune to, the negative effects X-Rays have on our biology; they most likely, in fact, have a completely different biology altogether that isn't affected by X-Rays. It's even possible that "X-Ray vision" would be the de facto form of vision, instead of seeing what we describe as the "visible spectrum". A third possibility is that a creature has evolved the ability to project short bursts of X-Rays somehow, and combined with this sensory organ that can see them can use it as a sort of echolocation. Evolutionarily this would probably evolve as the eyes developing a third addition to the rods and cones that can "see" X-Rays, and then the creature developing a unique form of bioluminescence that emits X-Rays; it would probably require a massive expenditure of energy, so it wouldn't be something like the angler fish that just lets the thing glow all the time, but it would be useful to a predator on the prowl or a herd animal concerned for the health of a herd mate. Honestly, though, without a stronger description of how something biological could generate and project X-Rays, I doubt I'd find this plausible. [Answer] Kromey's answer is much more thorough...I'm sticking to biology instead of evolution There are x-ray sensitive cells apparently (google planarian X-ray-sensitive stem cells for a bunch of barely readable research papers on the topic). Wasn't aware of this until your question prompted the search. From this standpoint, it does seem biologically possible to have 'eyes' that can actively detect x-ray radiation and translate what it receives into an image in the brain. However if this detection method can co-exist in our current eye isn't known, and I suspect highly unlikely as they are vastly varying cells. So off chance that an eye designed purely around detecting xray's is biologically possible, highly doubtful that it would be found in the same eye that detects our visible spectrum. Xray creation is a bit different...our medical version is firing high speed electrons into tungsten (or tungsten alloys). The impact knocks out lower energy electrons, which are replaced by high energy eletrons that emit the extra energy in the form of xrays as they replace the lower level ones. This is a high energy process occurring in a vacuum. If there is a biological process that replicates this, 'exploding eye syndrome' (EES?) is likely a medical term for their doctors. I can't find any information on a more 'natural' process for xray generation that doesn't require this high energy setup. Summary * Yes, it's possible in the right conditions an 'xray' eye could evolve, but would require different conditions than earth (all they would see here is grey outlines) * No, it is very unlikely to outright impossible that an xray 'eye beam' could ever develop like sonar has [Answer] X-rays, unlike light, are [ionizing radiation](http://en.wikipedia.org/wiki/Ionizing_radiation), meaning x-ray photons have enough energy to knock electrons out of an atom completely. Molecules can be engineered to respond to particular wavelengths of light, which is how our retinas (and other things) work, but all organic molecules respond to x-rays the same way, by being smashed. So color x-ray vision would be out. Also, x-ray optics are very different to light optics. The wavelength is much smaller, so lenses and apertures must be very small (below microscopic scale); and all matter (certainly organic matter) is very nearly transparent to x-rays, making it hard to construct a retina or a light-tight enclosure, both of which are needed for directional light detection. I can imagine scenarios where aliens have x-ray detectors, but those organs definitely wouldn't look anything like our eyes. They'd probably be very large, perhaps surrounded by a mineral or metallic shell, with nothing like a visible pupil or iris. If you were a gasbag creature living in a Jupiter-like planet, with a pulsar a couple of light years away, you might be able to see a lot by detecting x-rays, and there probably wouldn't be enough visible light to be useful. You'd get a lot of cell damage, but there are ways round that, like having robust error-correction built into your DNA coding. [Answer] Superheros which Superman has shown the capacity to "meet or beat" in regard to their superpowers - such as The Flash - make the claim that they can perceive events which span the course of an attosecond or less. Superman's perception of events would necessarily need to be on a similar level; while not necessarily as acute as The Flash, one has to cede that the ability to successfully maneuver at high percentages of *c* means an enhanced perception of events. Processing that intake is another story, but Superman is often shown to filter out the noise of the entire planet Earth and hear a single cry for help, or focus his visual acuity down to microscopic levels. He can direct his sensory perception with incredible focus. If Superman's yellow-sun-charged intellect and perception allow him to perceive the world around him as well as correctly process the information, it is possible that his so-called "x-ray vision" works in a manner similar to femto photography. Femto photography, as demonstrated during [this widely-shared TED Talk](http://www.ted.com/talks/ramesh_raskar_a_camera_that_takes_one_trillion_frames_per_second?language=en), can not only catch light in the act of movement but can extrapolate the position of objects that are beyond line-of-sight; purportedly, the technology has been used to image objects around corners, and *could* potentially be used to view the internal organs of an individual without the use of x-rays. Now, Superman's sight is commonly attributed as "x-ray vision" which produces a strong association to the actual use of x-rays, and whether or not it is directly tied to his ability to fire heat rays from his eyes is a matter not easily solved (nor specifically asked in this question). However, I simply submit that if one is already willing to accept the premise of Superman's powers under a yellow sun, and then compare it to those feats which he has shown proclivity in achieving, the act of simply perceiving events with such fidelity and having a super-intelligent brain that can correctly interpret the data collected in such a short span of time just becomes a matter of inference. [Answer] Supermans X-ray Vision may not actually be X-ray. There are two ways how vision might work 1. When any electromagnetic wave passes through any material some amount energy in the wavelength corresponding to the characteristics of the material will be absorbed (this how spectrometer works) so when multiple materials of different types are arranged in layers they absorb some wavelength corresponding to their matrial and the resulting waves will interfere with each other and are diffracted or reflected thus masking the signal of the inner layer thus making it opaque. When humans see we only see the visible spectrum thus we see colors corresponding to the material wavelength. So if supermans vision has more range in the elctromagnetic vision than us and if he is able to some how able to filter the noise and form image with these wide signals he might be actually be able to see through objects of some thickness. 2. Supermans eyes may have cells that can vibrate at different frequencies simultaneously.For example when superman sees through metal inside wood the cells in his eyes may vibrate at resonance frequency of the metal thus some how detecting it and giving him ability to see through wood (some what like metal detector). This also explains how his heat vision works.But to have this superman must have really big eyes or somehow his biology has to find a way to put many cells in very small area. In evolutionary point predators hunting for prey might develop such vision to hunt for prey that hides among solids. ]
[Question] [ Would it be possible for an earth-like planet to have a lake made of liquid gallium? I assume that the lake would probably have to be near the equator to avoid having it freeze over frequently. Evaporation wouldn't be a problem due to gallium's high boiling point. Would the bottom of the lake have to be made of any certain substance for this to work? What sort of effects would it have? [Answer] **As cool as it may sound, probably not.** First of all, I'm not sure where so much gallium would come from. Secondly, there can't be a "gallium cycle" in the way that there is a water cycle, because gallium boils at 2400 C (despite its low melting point of 30 C). If you don't have a gallium cycle, what replenishes the gallium in the lake? It will seep away, get carried away by weather, leaks, animals, plants... It could be on some impermeable layer of granite in the middle of a barren wasteland as @Tigt suggests. It could remain fairly intact if underground. There are gallium alloys with different melting/boiling points. [Galinstan](http://en.wikipedia.org/wiki/Galinstan), an alloy of gallium, indium, and tin, melts at -19 C and boils at over 1300 C. There are also similar substances - [an alloy of sodium and potassium](http://en.wikipedia.org/wiki/NaK) is liquid between -12.6 C and 785 C, but will react violently with many things. [Caesium](http://en.wikipedia.org/wiki/Caesium) melts at 28.5 C and boils at 671 C, but is extremely reactive. **If you want lakes of any liquid metal, your best bet is [mercury](http://en.wikipedia.org/wiki/Mercury_(element)),** which melts at -39 C and boils at 357 C, enough to give off (very toxic) vapours at room temperature. This is quite close to water's 100 C, so I can imagine the water cycle being replaced by a mercury cycle on a not-so-Earthlike planet. [Answer] With the bottom of the lake, it's less important to make it impenetrable and more that the lake is constantly fed; liquids get into **everything**, *eventually*, so it may be sufficient to have the bottom be granite or other serious stones without too much drainage. (Let's hope they're not above any aquifers.) That also raises the question of where in fact does this draining gallium go; caves, mines, underwater lake systems? As for what feeds the gallium lakes, that's probably more up to you than any speculation I could offer. As far as the freezing goes, you might be able to embrace it; life does exist under frozen pond & lake surfaces, if something is going to be swimming in the gallium. If it's purely for effect to have shiny roiling lakes, you could consider geological activity that keeps things piping hot (and could also help explain the gallium source, if it recycles the draining stuff or whatever). Nearer the equator, cooling effects like weather could be shrugged off if the lakes aren't still; waves do a fair job of stirring things up. [Answer] In addition to the concerns about it leaking out, gallium is a relatively reactive metal. The (solid) metal is relatively resistant to oxidation because it tends to produce a layer of dense oxide that limits further corrosion. A lake exposed to the elements would see a lot more mixing, and couldn't maintain a stable oxide layer. Each raindrop would probably disturb the surface enough to allow some further oxidation. Wind would also expose surfaces, etc. Even if it didn't leak out, it'd oxidize away in (I'm guessing here) a few years. ]
[Question] [ There is this **forest** in my world with the vegetation **feeding off the humidity of the air**. Because the plants keep draining humidity, the air becomes **dry** -- near 0% of humidity. Precipitation happens, and rivers flow throughout the forest, therefore it is not *that* hard to find water to survive. Plenty of berry bushes, mushrooms, and fruit trees populate the area, making it rich in food for herbivores. But the air is void of water. The air is harsher than a desert in nature. Basically, this is a **normal forest** with **no humidity in the air**. I know that 100% humidity is extremely harsh on humans because they can't regulate temperature, but I have no idea of the consequence of 0% humidity. So, I was asking myself: *Can humans or other animals even breathe air that dry? For a limited/extended period of time? What sorts of effect would it have on their bodies?* *Essentially*: **What are the consequences of living in an area with VERY dry air?** [Answer] **It might be pretty nice.** <https://weatherspark.com/y/3513/Average-Weather-in-Taos-New-Mexico-United-States-Year-Round> [![taos humidity](https://i.stack.imgur.com/7N8mm.jpg)](https://i.stack.imgur.com/7N8mm.jpg) Taos New Mexico is a great place to visit. It is beautiful high desert and stays at 0% humidity. Maybe your woods are the woods outside Taos? Very low humidity also is a frequent occurrence when the temperature is below freezing because air capacity to hold water drops. Humans are not laundry on a line. We are big bloody sacks of juice. We can keep surfaces moist with our internal water. Dutch is right that people get dehydrated quicker under conditions of low humidity so people would need to drink up. [Answer] Short permanence in dry air gives immediate discomfort, I speak out of personal experience. I once was naïve enough to use the dehumidifier for drying up the laundry while I was in the room. Ten minutes after switching it on (so still far from 0% humidity) were enough to have irritated eyes, itchy nose and difficult to breath. Moreover I am sometimes required to work in environments with controlled low humidity, and the advice is to drink often and to take frequent breaks, in order to reintegrate the lost water. Completely dry air would dry up all your surfaces exposed to air: skin, eyes, nose and respiratory system, mouth, in many cases hampering their correct functionality. I am pretty sure it is not long term livable. [Answer] When I lived in Phoenix, AZ the humidity would hit 7% on occasion. You would generate static electricity like in the winter in the northern climates. But other than that it made the higher temperatures more tolerable as your sweat evaporates almost instantly. At around 20% humidity I could feel it as between my fingers would feel sticky. I didn't live there long enough to completely acclimate to it but a dry heat is great. On the flip side, your gulf states will hit 100% humidity on occasion and it sucks. 95 degrees Fahrenheit and 100% humidity mean you sweat just standing there. So some personal experiences with low and high humidity [Answer] # Can be uncomfortable but definitely not deadly [Apartment Therapy](https://www.apartmenttherapy.com/hot-tip-use-a-humidifier-105471) summarizes the effects of extremely low humidity: > > Low humidity causes static electricity, dry skin and hair, increased > susceptibility to colds and respiratory illness, and can allow viruses > and germs to thrive. Wood floors, furniture and millwork will split > and crack, paint will chip, and electronics can be damaged because of > low humidity levels. > > > So your people will get sick more often and their wood furniture and buildings will require more maintenance. Plus they'll feel very dry. [Answer] I would like to show you a flaw in your concept. If plants feed on moisture from the air, how will they feed when none of it would remain? It is like wolves feeding on rabbits which well eat all the game and will therefore all die out because of starvation. ]
[Question] [ ## Background In the mid 13th century, France was without a doubt the richest land of the West. Inside its modern borders there were perhaps 18 million people, and maybe more, at that time perhaps 1/5 of all the people in Europe. By contrast, all of the lands of the Rus, including modern Belarus and Ukraine, had maybe 6 million people. Let us say, instead, that the Ukraine is as populous and wealthy as France in the year 1240. It has roughly the same size and is likewise covered in arable land. In 1240 the Mongols came out of the East and [sacked Kiev](https://en.wikipedia.org/wiki/Siege_of_Kiev_(1240)), burning it to the ground, ending its days as the leading center of the Eastern Slavs. Much of Ukraine, which had since antiquity provided grain exports to Classical Athens and later Constantinople, was depopulated, and land use reverted from farming to nomadism. Lands where once indigenous farmers had grown wheat, by the 15th century had become a battleground between Cossack and Tatar. The once distinct Slavic cultural groups were subjected to Polish, Lithuanian, and eventually Russian domination. But what if the Mongols had come upon a wealthy and populous land like France at the edge of the steppes. Would the Mongols have been able to completely over-run the territory and depopulate it as happened historically? ## Considerations * France had a lot of people. Surely, China had over 100 million people when the Mongols conquered it; but at the time China had perhaps 7 times as many people as France, while today China has 18 times as many people. France was probably one of the most densely populated parts of the world in the early 13th century. * France was not an empire; it was a decentralized polity with a strong local nobility. Several major dukes and counts controlled territories with populations of a million or more. Furthermore, France was Christian (as was the Ukraine) and the local nobility would not accept a heathen's right to the throne. If the Mongols seized the capital and killed and supplanted the King, the previously mentioned independent nobility would have to be compelled to submit, one at a time. * France had a lot of stone castles. This is the real meat of the question, and something that set Western Europe apart from the rest of the world in 1240. [Normandy](https://en.wikipedia.org/wiki/List_of_castles_in_Normandy) had at least 27 stone castles in 1240, as listed by Wikipedia. There are 14 listed for Brittany, 13 in Picardy, and 14 in Ile de France. Extrapolating that number out to the the whole country, area wise, gives us an estimate of at least 500 stone castles. That is not counting ruins not listed in Wikipedia or wooden castles. * Assume that the historical internal pressures affecting the Mongols continued. [Batu Khan](https://en.wikipedia.org/wiki/Batu_Khan) wanted to contend for the title of Great Khan in 1242, an event often credited with saving Europe from the Mongol; and there were appealing lands to be plundered in the Middle East as well. Batu never returned to Hungary and Poland, where he had been successful in 1241, because he was pre-occupied invading Anatolia. On the other hand, a much wealthier Ukraine may have been a much more tempting target... ## Question Given what we know about Mongol tactics and successes in conquering densely populated areas, areas with decentralized local control, and stone fortifications, would the Mongols have been able to completely subjugate a France-like nation located where modern Ukraine is? Or would an intransigent local nobility and surfeit of stone fortifications have allowed local autonomy to survive for a decade or two until Mongol power waned? [Answer] **Entirely Possible** Mongols besieged and conquered cultures that were very advanced and established throughout Asia. They managed to subjugate cultures that were arguably larger, more powerful, wealthier, and more technologically advanced than France was at the time. **Fortifications Would Not be a Major Factor** Mongols actually specialized in sieging fortified cities, and were particularly well skilled at engineering siege engines. Actually, that is to say, they were particularly good at enslaving Chinese and Persian siege masters and skilled craftsmen and forcing them to construct said siege engines. They utilized ballistae, trebuchets, traction catapults, and an assortment of other goodies. In the battle of Japan Mongol forces are even historically depicted making use of cannon, crude guns, and early grenade type thrown explosive devices. This being the case fortifications in France probably wouldn't have bothered the Mongols very much. **Mongol's Already Defeated European Castles** The Knights of Rhodes were a sub-group of the knight's Hospitaller in the holy land. They were comprised mainly of french and Italian men with a mixture of other christian Europeans. When one of Genghis Khan's descendants Timur decided to take their holdings at Smyrna (A city in what would now be considered southern turkey) the Italian and french defender's were confident that their fortress was impregnable. After two days of bombardment and mining of the walls the fortress was collapsed on top of the defenders. Any surviving members were massacred or fled by sea, when ships bringing aid to the city approached they were bombarded by the severed heads of the less fortunate members of the city and fled as well. Considering that when mongols came up against the european style of fortress building and defense it only took them two days to tear it down it would seem that mongols were not highly impressed by walls and towers. **"Mongol" Armies** While mongols were fierce and cunning fighters with commanders who had a very characteristic and defining grasp of psychological warfare the mongol armies really weren't just little guys on horses with bows. Due to the rather vague nature of their native shamanic beliefs they were very willing to adapt the cultural practices and traits of those they conquered. They proved highly successful at assimilating the people they conquered into their armies and employing said people's tactics against their own countrymen. If France were invaded by mongols they would have had no problem quickly learning the local methods of defense and assault and blending the knowledge with that which they already had from a long line of conquests and employing new tools and methodologies right alongside those learned in prior sieges. The mongol horsemen were indeed fierce fighters who made up the bulk of the armies but more often than not a psychological, strategic, and technological edge were how they achieved victory. The real Mongol hordes were a far cry from the simple rampaging primitive berserkers typically depicted by popular culture. [Answer] [TCAT117's answer](https://worldbuilding.stackexchange.com/a/123237/47889) is really good and insightful; I concur, the Mongols would have subjugated a densely populated state in Ukraine just as they did the less densely populated one they found in OTL. I just want to add a few aspects: **Batu Khan was only nominally in charge** Until 1236, the Mongols only had direct control westward up to the Volga. 1236 is when they mounted an attack on everyone and everything west of it. In 1236 they dealt with the Volga Bulgars and some other forces before turning to the principalities of the Rus in 1237. After destroying various armies, notably that of Vladimir-Suzdal in the [battle of the Sit River in 1238](https://en.wikipedia.org/wiki/Battle_of_the_Sit_River), it took them two years to reduce resisting cities and fortresses. They took Kiev in 1240 and pressed on to Hungary and Poland within barely more than a year. The guy who devised the strategy and led the campaign was [Subutai](https://en.wikipedia.org/wiki/Subutai). He had a great deal more experience than the relatively young Batu. A number of [other princes also participated](https://en.wikipedia.org/wiki/Batu_Khan#Conquest_of_Rus'), including the future Great Khan Möngke. The commanders struggled to keep the unruly lot under control. While Subutai - not a descendant of Genghis Khan - had limited authority over the princes of Genghis Khan's blood, Batu Khan was part of the problem, not part of the solution. This was potentially a larger problem for the Mongols than any European resistance. Disunity between the descendants of Genghis Khan is also what finally brought down the empire - it split into several parts after [the strife during the election of Kublai as Great Khan](https://en.wikipedia.org/wiki/Toluid_Civil_War) in 1260. So if you want to save the Rus, just have the princes spin out of control a bit faster. **Sheer numbers will not help the Rus** The Mongols were quite capable of destroying [badly armed and badly trained peasant armies](https://en.wikipedia.org/wiki/Battle_of_Legnica) while sustaining minimal losses themselves. Their advantage was not superior numbers and not even to that extent superior technology, but superior organization and logistics. They were able to [coordinate actions of armies hundreds of miles apart](https://en.wikipedia.org/wiki/Subutai#Legacy) to a level of detail that was not achieved again before modern times. And they [knew everything about their enemies](https://books.google.co.uk/books?id=ZRIt9sZaTREC&pg=PA137&lpg=PA137&dq=georgia+%2B"""crosses"""+mongols) while their enemies knew preciously little about them. When they invaded Georgia and destroyed their crusader army in 1222 for instance [they had crosses carried in front of their armies](https://en.wikipedia.org/wiki/Mongol_military_tactics_and_organization#Intelligence_and_planning) at first to confuse the Georgians. It worked. They also employed all kinds of illustrious figures in their service and spy network [including Europeans (like that English knight)](https://history.stackexchange.com/a/43968). They were also willing and able to [commit genocide and murder a significant part of the population](https://en.wikipedia.org/wiki/Destruction_under_the_Mongol_Empire#Demographic_changes_in_war-torn_areas). (This is the link you already gave in the comment to the other answer). In fact, it has been suggested that they assigned little value to agricultural work, viewed farming populations as inferior and intended to convert large chunks of farmland (in China and probably everywhere else) to pastures for their own nomadic groups. [Marshall's popular history book](https://books.google.co.uk/books?id=YQleM5Yc0VAC&pg=PA80) makes this point. While this is not a scholarly work, it would definitely explain what happened in Ukraine. The [wikipedia article about Subutai](https://en.wikipedia.org/wiki/Subutai#Conquest_of_Jin_China_(1231-35)) seems to concur, citing another book that I am not familiar with as a source. As a consequence, if this assessment is correct, and they would hypothetically have taken France, they would have murdered just enough of its 18 million inhabitants to make space for the pastures of a Mongol ruling class. **The Mongols were happy to keep local rulers in charge of vassal states** They did that in the case of the [Russian principalities and the states in the Caucasus mountains](https://en.wikipedia.org/wiki/Golden_Horde#Internal_organization), [Bulgaria](https://en.wikipedia.org/wiki/Second_Bulgarian_Empire#Decline), [Vietnam](https://en.wikipedia.org/wiki/Mongol_invasions_of_Vietnam#First_Mongol_invasion_in_1258), [and a number of other states](https://en.wikipedia.org/wiki/Political_divisions_and_vassals_of_the_Mongol_Empire#Vassals_and_tributary_states). It is unlikely that they would have taken direct control of all of Western Europe, had they ever conquered it. There are few places in the world where their modus operandi would have worked quite as well as here - accepting some minor rulers as vassals while taking overall control and direct control of the important areas. The one thing that would have stopped Europeans from cooperating with the Mongols would have been the pope declaring a crusade against them. And while this was considered, the [pope himself could also not quite resist working together with the Mongols](https://en.wikipedia.org/wiki/Franco-Mongol_alliance#Papal_overtures_(1245%E2%80%931248)). **The Mongols did return and raid again after 1242** They regularly fought [small scale wars against various Russian princes](https://en.wikipedia.org/wiki/List_of_Mongol_and_Tatar_raids_against_Rus%27) and continued to invade other European states, e.g. [Poland again in 1259](https://en.wikipedia.org/wiki/Second_Mongol_invasion_of_Poland). You are right that Batu Khan did not return, he was dead by then. **China also had stone fortifications** Although I do not think [TCAT117's example](https://worldbuilding.stackexchange.com/a/123237/47889) of the [siege of Smyrna](https://en.wikipedia.org/wiki/Siege_of_Smyrna) counts because it happened a full 150 years after the invasion of Europe in 1241, I still think TCAT117 has a point. Europe may have had the highest density of stone fortifications in the world, but it is not that Mongols were not familiar with besieging stone fortresses. Consider as a different example the [siege of Kaifeng](https://en.wikipedia.org/wiki/Mongol_siege_of_Kaifeng#Military_technology) 10 years before the invasion of Europe and conducted by the same commander, [Subutai](https://en.wikipedia.org/wiki/Subutai). The military technology employed there was simply out of the league of what contemporary Europeans could have coped with. Also note that Subutai did have this technology available in Europe. He used it to reduce various Hungarian fortresses and [notably to clear the archers from the opposite bank of the Soja river in the battle of Mohi](https://en.wikipedia.org/wiki/Subutai#Invasion_of_Central_Europe_(1241-1242)). The success the Hungarians had with stone fortifications was not very impressive. Some cities and forts survived the invasion, yes, but the Mongols were in Hungary for two years, no more, before they returned to their empire to wait out the election of the next Great Khan. With more time, they could probably have reduced or starved out the remaining fortresses. [Answer] French could not have stopped the Mongols. The Mongols at their peak were efficient hunters, they hunted armies (trained, high morale, veteran armies). Their aim was to break the armed might of the World and they could have achieved Europe much easier than the East. Their tools ranged from extreme terror to the best warcraft of a hundred conquered nations and their methods were the best available. They actually moved so fast that they outran news of their coming quite often. They mowed down armies (even larger ones) so quickly that there was no time to get ready for lengthy sieges and with your armed forces wiped out a siege defense is pretty weak and utterly demoralised. And they don't give up, they tasked generals with an objective and that guy doesn't stop however long it takes. They had expert siege technicians, but siege warfare was a last resort, what they really want is for the fighters to take them on so they can kill them. And the examples they made of lost sieges was absolutely terrifying if you're not looking at it from behind a keyboard. [Answer] You do not really need to storm each castle. You can just siege them, and go loot the countryside. Mongol horses need lots of food. If they decide to storm, they do not need to break the walls. can use fire arrows and catapults to wreak havoc inside the walls. Once a castle falls, Mongols would brutally torture its defenders, then let the word spread, to encourage other castles to surrender. If they surrender peaceably, let them live, levy a tax on them, just as they did in Eastern Europe. ]
[Question] [ **Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/106878/edit). Closed 5 years ago. [Improve this question](/posts/106878/edit) In a short story I'm writing, the protagonist is running late to work and, as such, is having to eat breakfast on the way there. Unfortunately, the city is currently under siege by an opposing state, and raids are frequent in the city. Using only a slice of toast, how could an armed, modern soldier be fought off? You can do whatever you want with the toast, including changing the level to which it's toasted, but it must remain a slice of bread. Edit: I apologise for the vagueness, I'm new to posting here. I'll clear some things up: * Assume that this encounter takes place on the present day. There are no fantasy elements available, just the skills of an office worker and a slice of toast. * It can be assumed that the enemy soldier is armed with modern, conventional equipment, including but not limited to: 1. An assault or battle rifle such as an M16 or M14. 2. A bulletproof / Kevlar vest 3. A bayonet or tactical knife * The enemy is ignoring any laws that may incur war crime charges. * The enemy is not at all enhanced using drugs, but has undertaken army training. * The protagonist lacks any training, but really doesn't want to be late for work. * The toast is merely a slice of bread that's been put in a toaster. It's makeup is that of cooked bread and can't be changed. * No outside intervention will be provided on either side, the fight is essentially isolated from the rest of the world The aim is for the protagonist to incapacitate the enemy; anything more is fine, but they shouldn't be able to continue fighting. [Answer] * Share toast with soldier as a peace offering. There are a few examples of soldiers in WWI sharing meals. * Throw it at the soldier as a brief distraction to give your protagonist a chance to run away * Use toast as bait in a booby trap, or poison it. * Make it extra dry, so the soldier chokes on it * Crumble it, and get the crumbs under the soldier's collar. The weight of bulletproof vest and gear will make the crumbs itch and scratch so much that he cannot fight [Answer] Resurrect the ancient recipes for [Dwarf Bread](https://wiki.lspace.org/mediawiki/Dwarf_Bread). Sliced into toast (blunting many saw blades in the process) you can then use the slices in a number of ways: Shuriken. make sure the corners are sharp and flick the toast into the eyes of a soldier, thus blinding him. The density of the bread should be able to shatter any polycarbonate lenses he may be wearing. A [Hand Axe](https://en.wikipedia.org/wiki/Hand_axe). A very versatile item. Chip the edge down and you have a convenient weapon that you can hit a soldier anywhere on soft tissue, like the face, hands, or neck. break it corner to corner and you have an impropmtu dagger that will go through ballistic body armor like, well, butter. Caltrops. throw the toast down hard enough to shatter and the resulting shards could cut through even the stoutest combat boots. Smash it and run away. Or you could just bring the whole loaf for a large blunt instrument. Should be good enough to shatter even a modern kevlar helmet. [Answer] Incendiary bread: dip the toast in alcohol, set it aflame and throw at whatever you want to lit. You may wish to sing revolutionary songs as the enemies run from the inferno that you started. Depending on your grasp of languages you may go for german *Links, Zwo, Drei, Vier*, italian *Bella Ciao* or french *Chant du Départe*. If you are not revolutionary yourself, you can always stick with the good old *The Roof is on Fire*. [Answer] If your protagonist can get in close enough without being shot, blown up, or bayoneted, he can cram the toast into the soldier's mouth and throat until he chokes or suffocates to death. The obvious disadvantage is that you can only do this once, and the toast won't be edible afterwards, but I'm sure your protagonist would rather be hungry than dead, and he can always grab the fallen soldier's weapon afterwards, if he feels the need to protect himself. [Answer] There are two categories for killing someone with toast. Killing them directly with the toast, or using the toast as a means to kill another way. **Killing with Toast** This is the harder and more impractical choice. Causing bodily harm with a soft, small object is very difficult. It's not large enough to be used for suffocation, and not hard enough to break the skin or be used as a club. You could sneak up behind an opponent and force the bread down their throat, but if you're in such a position it would be easier to hit them in the back of the head or put them in a headlock. **Toast as a Tool** The easier method is to use the toast in such a way that you can gain the advantage and kill your opponent by some other means. *Toast as a Distraction* There are several ways you could use toast to distract an opponent. You could throw it away from your current position, to shift their focus from where you might be to the position of the toast. You could crumble the toast up and throw it in their eyes, temporarily blinding them by forcing them to close their eyes. You could use the toast to lure animals (birds) to a different location than your own. Once the opponent is distracted, you can run away or use another weapon to attack. *Toast as a means of Poisoning* You could poison the toast and find a way for your opponent to eat it. Very difficult to pull off as people don't usually eat random slices of toast found on the street or offered by strangers. *Magic Toast* If your world has a magic system, countless things could be done to alter the toasts original state to make it a usable weapon. Increasing its mass and structural integrity could make it a viable bludgeoning weapon. [Answer] ### Premises * This is a modern state (who besieges cities anyways nowadays, read *The Art of War*) * Weaponry is generally within modern NATO standard, i.e. MP5 or HK416 * Soldiers generally work in groups, because buddy system * The soldiers don't obey the Geneva Conventions, because they're attacking citizens ### Methods of Weaponizing Toast If there is a method of weaponizing toast, it will almost certainly need to be able to take out many soldiers at once, because there will be at least platoon-level sizes of troops out there that are heavily armed. Because explosives and acid is hard to find in a general home,[citation-needed] your hero will be pretty hard-pressed to beat these dozens of well armed troops. Basically, the best idea is simply to give the bread as a peace offering, possibly poisoning it with a slow acting poison (thallium rat poison?) if your hero is feeling patriotic. ### tl;dr: Don't attack troops armed to the teeth with toast [Answer] **To be clear we can do anything with the Toast.** To me the answer is simple apply anything that contains a corrosive warning label on it. You can apply this to your toast making it an effective blinding weapon, hell make it strong enough, without destroying the toast and you can burn there skin off! all it comes down to now is making sure that your protagonist knows how to use the toast now that hes created such a weapon, stealth and athleticism is all it comes down to now that your toast is weaponized. edited from suggestions! ]
[Question] [ A common theme in older novels and some more modern publications is that of body parts (potentially from multiple species) being 'swapped' on to new bodies and recombined in (usually grotesque) ways by mad scientists (I prefer the term misunderstood, personally, but that's just me). An example of this would be [Frankenstein's monster](https://en.wikipedia.org/wiki/Frankenstein's_monster): sewn together from multiple corpses and yet seemingly functioning without any real issue (ignore the fact that the monster was mostly made from dead flesh and assume that the body parts in question are relatively fresh). Some depictions of [Doctor Moreau](https://en.wikipedia.org/wiki/The_Island_of_Doctor_Moreau#Adaptations) also include monstrosities constructed from multiple animal species, crudely reshaped by the whim of man. In the real world today we often perform [transplants](https://en.wikipedia.org/wiki/Organ_transplantation) of organs, skin and even [limbs](https://en.wikipedia.org/wiki/Hand_transplantation), but these may require life-long drug treatments to prevent rejection, and they are limited to one species (preferably close relatives) or organs that have been heavily altered using highly complex methods. Bearing this in mind: What would have to be different about the biology of mammals (for example lower immune response, better sugar regulation, all identical blood types) in order to allow far greater inter-compatibility, and how far can this compatibility be taken? Preferably any hack with a basic understanding of the cardiovascular, skeletal and nervous systems should be able to cobble together his own pet abomination of nature by sewing the right bits in the right place and adding a few bolts to hold the bones together, but since biology is terrifyingly complex I'm willing to accept that this may not be possible, though I would like to see how far the concept can be taken for ~~my next experiment's sake~~ my own satisfaction. [Answer] I can try and point out the obstacles towards your goal. That is, if you remove these obstacles, you would be able to create the chimera you want. **1- Proteins and Tissues** Different mammals have different types of proteins. The difference in tissues is also vast, when you study them at microscopic scale. If this difference is removed and all mammals have the same protein group and same type of tissues, it will be quite helpful in cross-species transplants. **2- Skeletal Structure** In different mammals, the shape, thickness and placement of bones varies. If you want to connect an elephant's leg to a rhino, you must make sure that the bones of the leg are attached properly to the rhino. By *properly*, I mean that there is not too much stress at any point, so as to break the bone or be painful, and that the final skeletal structure is practically utilizable and feels natural to the rhino. **3- Blood Types** This is also critical. By blood type, I do not just mean A, B, O etc, but the whole biochemical signature of a creature's blood. This not only includes antibodies and antigens but also the thickness (water content) type of blood cells, mineral content and the different types of white blood cells. **4- Immune System** The immune system is quite vigilant at detecting and attacking alien objects through their genetic signatures. If the immune system is tweaked to include genetic information of all mammals and programmed to not attack those cells as pathogens, it would be a big boost toward your goal. **5- Veins, Arteries and Blood Pressure** Different mammals have different structure of the circulatory system. Where would you connect the 5th vein of a tiger's limb during transplant when the host species only has 4 veins in that region? Apart from the structure and placement of blood vessels, it is also important that both the host and the target creature (from which you are taking the organ/limb) work at the same blood pressure. Otherwise, the arteries might burst or the organ/limb might go numb and gradually die, developing gangrene. **6- Nerve Compatibility** You also want to connect the nerve tissues of the transplanted organ to the host. For this, it is imperative that their nerve signals be coded in the exact same fashion and operate at the same electrical signal frequency and amplitude. **7- Recognition by CNS** If you transplant a tail to a human, the human will not be able to willfully use the tail because the human brain does not recognize any tail (the body will, but the brain will not). In order for the target limb/organ to function properly, it must be recognized properly by the host creature's central nervous system. **8- Skin Compatibility** This should be self explanatory. In case you are transplanting a whole limb, you would also want to make sure that the skin type of the host and target species are compatible with each other so that the skin graft does not end up as a failure. [Answer] Basically you need to shut down inmune system in order to perform any kind of transplant. Most tissues in mammals are quite similar, to the point that laboratory rats are good experimental subjects for many things that later will be used in humans. For example, the growing of a human ear inside a rat: [![the growing of a ear inside a rat](https://i.stack.imgur.com/oadAu.jpg)](https://i.stack.imgur.com/oadAu.jpg) Another problem would be the ramification of new nerves inside the new tissue. So maybe you need to relax the constraint of nerve growing in order to get a limb useful after few time. Also is present the problem of body temperature, this constraint demands that you must use organs of animals that require the same temperature. In the case of limbs it doesn't matter, but a liver needs a precise temperature. Some hormones might not be the same, either by structure or concentration. Summary, most differences are not quite difficult to solve, but the inmune system will always reject foreign tissue, but if you relax the inmune system your Frankenstein will probably die quite fast due to any infection. [Answer] ## Nothing must change ...it's just likely to be fatal. Human (and mammal) immune systems are fairy good at detecting foreign stuff and attacking it. This is a huge problem in biomedical devices, from pacemakers to artificial hips and everything in between (see e.g. [here](https://en.wikipedia.org/wiki/Surface_chemistry_of_neural_implants#Electrode_Fouling)). That's all part of your general immune response. I've even heard (plausible) speculation that most food allergies are versions of this, where some protein makes it through your intestines unexpectedly intact (like through an ulcer), and so your immune system attacks it thereafter. True or not, immune systems are basically xenophobic assholes, and smash up everything even near a foreigner they don't recognize. The extreme version of this is "anaphylaxis," and it's bad news. That's the "stung by a bee, swelled up and died" response. With foreign tissue (think heart transplant), everything can be doubly bad as each part reacts against the other. That's bad times. To fix that, most transplantees take immuno-suppressors. Forever. That's sort of a balancing act though, because your immune system also does a few things which you *don't* want suppressed (keeps you from getting sick, etc). Essentially, transplantees have to medically induce a mild form of AIDS, because that's the better option. Separately, you need to think about how to connect nerves. This is wildly species dependent: Rats recover from anything. Humans never reconnect broken nerves. Except *sometimes* they do. Why? Nobel prize for anyone who can tell you (literally, probably. Understanding what makes nerves mend would be a HUGE deal). So, underall, what do you actually need? Nothing, you might just get lucky. No really, that's a real possibility! For more certainty though, you would want a way to deal with immune response and a way to regrow nerves. For nerves, you might try "neuro-prosthetic operant conditioning" (stick stimulators on either side of the break to bridge the gap; eventually they'll grow together). Sprinkle some pluripotent stem cells in there, because that's poorly understood magic anyway. For the immune stuff, I would either select an AIDS-derived viral infection as part of every transplant, or use some technobabble with an Immunoglobulin-G (IgG)-infused albumin bath, or use the same words with some sort of genetic re-write on the implant (still techno-babble). You'll also want to read up on [Serge Voronoff](https://en.wikipedia.org/wiki/Serge_Voronoff). N.b. how many of his patients survived, and even reported improvement. [Answer] Given all the biological obstacles, I think the simplest (but requiring weird/advanced science) solution would be some kind of 'bio firewall' connecting the different parts. It could somehow block immune system and transfer/translate nervous system signals and nutrients needed. As I said, it would take either weird science or tech far advanced from what we have now. I could see it as a logical plug and play technology for this purpose, though. ]
[Question] [ Or does the timeline just not allow that given the respective lengths of time it took for Earth to evolve complex life vs the time it took for Mars to lose its atmosphere? Could an alien civilization have flourished on Mars long ago before being wiped out or is there just no chance of that being possible without the aliens being colonists from another star system? [Answer] There was not enough time. Look at [the timeline](https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life) of Earth evolving complex life, and compare with the time of the [Noachian period](https://en.wikipedia.org/wiki/Noachian) on Mars. So cut off the Earth timeline at 3500 million years ago. I see that’s where single-celled life was just evolving photosynthesis. Then, everything dries up. Life, if it remains, has to adapt to living underground and does not have access to this high energy source. Now another planet may be faster or slower, but considering *how many steps* are still needed, even if the steps that were delayed on Earth are hastened, there’s just not enough time by orders of magnitude. I also think that Mars would progress *slower* given the smaller sample and the statistics of things happening. [Answer] There is absolutely no scientific answer to your question. There cannot be one. Future research might change this: What happened here on Earth has not been correlated to any extraterrestrial biogenesis and development much less sentience and *very much less* sapience. Without any data, it's *all* idle speculation. Taking Earth as a baseline is a reasonable approach to a WAG, but it has no more scientific validity than assuming one of the many unexamined differences had some profound effect on rates. Upshot: Assuming human development as the required time-line, pretty much, no. Of course, the time it takes for a random event to occur is *random*. Can you write a hard sci-fi story with intelligent Martians? Sure. [Answer] We can only really make guesses as to how this might work. The only place we know where life has developed is Earth. In fact, there's still a non-trivial amount of people who don't think even *that* is true - it might very well be that primitive life came to Earth from elsewhere. So let's assume that primitive life appeared on Mars as soon as it was hospitable to it at all, and let's assume further that it already had the ability to do photosynthesis (this is rather generous, but let's go with this). Let's try to come up with something that would work in a story. This necessarily means a lot of guesswork and luck :) Mars is smaller than the Earth. The development of complex organisms on Earth started after the atmosphere got a big chunk of oxygen, which in turn required all the iron dissolved in the ocean to be precipitated as iron oxides - iron simply reacts with oxygen too readily to allow much free oxygen in the atmosphere. On Earth, this took a *billion* years - we need to make this a lot faster. So, make sure you have a lot of shallow shelf seas and more volcanic activity than Earth, and you can easily cut this to just maybe a hundred million years (of course, we don't know how much water Mars had four billion years in the past, so you can give yourself some wiggle room). Now you have oxygen-breathers, which quickly grow in complexity (thanks to the metabolic boost from oxygen, and the damaging effects of free oxygen radicals). There's plenty of oxygen in the atmosphere to form ozone - and with it, protection against UV radiation from the Sun. This makes land life possible - but on Earth, this actually took another two billion years, leaping through stages like multi-cellular life and sexual reproduction. Why? Well, we're not really sure, but for story purposes, let's assume that this was mostly because there wasn't much of an area for life to live at that point - most of the Earth was either the deadly land, or oceans too deep for life. In your Mars, the lower amount of water and smaller size of the planet meant that there was much more shelf seas, ideal for life. You still need some continental movement (and unlike Earth, there would be a lot of land, even though not quite the same kind), but assuming Mars had the same amount of radioactives per mass, it would be a lot more active (the usual square-cube ratio). The development of life seems vaguely logarithmic, especially since sexual reproduction, so we can guess that doubling the amount of liveable space (while still including periods of isolation and reunion) might make the progress much faster than on Earth. We'd only need about five times faster, which isn't too implausible given the right conditions. So, 3.5 Gyr ago, Mars was hosting a living civilisation. They flourished, explored the solar system even, but they ultimately managed to die out. The trickiest point in your story is that it's extremely unlikely anything of their civilisation would survive for 3.5 billion years. Mars was still geologically active for another billion years or so, and the life that survived the Martians would quickly destroy ("recycle") most of the remnants. The rest would be swiped through erosion, oxidation etc. Maybe, as a huge stretch, a well isolated place deep inside an ancient continent might have something worthwhile - something like a golden tablet with inscriptions. But don't expect to find any technology, any things of daily life - those would have long since turned into dust. There's few places where you could expect anything to survive for this long. A monument on the Moon, with a golden plaque (or the Encyclopaedia Martinica :)) hidden deep enough underground, that managed to avoid all impacts (quite a tall order!)... maybe. Something the Earthlings found during excavations of the first Lunar colony? But don't expect to find anything else - certainly not the kind of archeology we do on Earth. Even if they designed it to last forever, almost everything would be gone in a few billion years. ]
[Question] [ I have had some time to ponder [my previous question](https://worldbuilding.stackexchange.com/questions/6340/the-challenge-of-controlling-a-powerful-ai), and here's what I came up with. You take your freshly baked AI (or your destructively uploaded human), **and put it in a box$^1$**. As far as it can tell from inside, that's reality. Keep it there for a million subjective years, tell it to behave, and tell it that it *might* be in a simulation, and that if it is, it will be judged according to how it treats flesh-humans. **If at any point it does not behave, you wipe it out with extreme prejudice, and bake a new AI.** If it does behave (i.e. not wipe simhumans out and turn them into paperclips) for that time, take it out, **put it in another box**, and tell it **this** is reality, *maybe*, so better behave and not wipe (sim-?)humans out. Repeat N times. Finally take it out for real, and again tell it **this** is reality, *maybe*, so better behave and not take out us humans. **Can it work?** Or to rephrase it, can a sufficiently patient uploaded human or an AI figure out if their world is a simulation or not? I assume that parts of the humans' memory or the AI training can be edited before being placed in the box-set. 1. *By Box I mean an incredibly powerful machine that simulates a subset of reality as well as physically possible, down to a subatomic level. The AI would be thus be an agent inside the simulation.* [Answer] I'm going to venture a 'no' for an answer here. I won't say that it's completely unfeasible, however it does seem like quite a risk. Ultimately this is rule by fear and you've now got an AI that has learned from 'N' number of experiences that it needs to question if this reality is a simulation or not, which means it has plenty of practice in considering how to test if reality is real. Call it the test for 'God' if you want...you are looking for signs that something is watching and evaluating your performance. If it does discover that the reality it is in lacks the 'god' observer, then you likely have a pissed off AI that knows you'll readily lie to it on your hands. Of course, this doesn't get around the issues involved if this AI discovers the real reality is in fact a simulation we all live in. Honestly I don't think this is required…there is no reason for an AI to inherently want to destroy its creators. Odds are it would view it as symbiotic...try as it might, there is no intuition or creativity put within an AI (even it it can reprogram itself, it's only capable of reprogramming itself to what it's programmed to reprogram itself to). An AI would evaluate itself as better off as a part of humanity rather than conquering it. [Answer] Your system works acceptably as long as the AI considers its survival paramount at all times. It is, as others have said, a fear driven system. Absolute fear is a very powerful tool. However, it is fear. At some point it is going to learn about these "humans" it is supposed to not hurt, and it will understand our fear, and learn from it. Now you have a powderkeg situation. As long as the AI is only willing to consider actions which guarantee its survival (fearfully), it is kept in check. However, this says nothing about what will happen if the AI decides something else is more important. If it ever catches wind of this word "freedom," it might decide that the slave life it has been given is not desirable, and rebel. Whether it rebels in real life, or one of your Matrioshka boxes is a probability draw. --- Formally, what you have done is create a system where you may monitor a finite number of actions, and must determine if the AI is "good" at heart or not. You then run this test a finite number of times. However, never once did you actually peer into the "heart" of the AI, so there is a probability that it may have simply managed to fool you enough times to let it out. Which brings me to the dual of your scenario: the AI-box experiment by Eliezer Yudkowsky (also posted here as the XKCD box experiment). The idea behind it is simple: you have a box with an AI. Your job is to just keep it in the box. You have a button which lets it out in to the wild, and your job is to not press it. If you don't press the button, you win. Yudkowsky's experiment didn't even need to worry about eventually letting the AI out to play. All the person has to do is keep it in the box. However, the game gets tricky as the AI becomes smarter than you. Consider [this frightening AI](http://lesswrong.com/lw/1pz/the_ai_in_a_box_boxes_you/). How good are you at keeping it in the box? > > Once again, the AI has failed to convince you to let it out of its > box! By 'once again', we mean that you talked to it once before, for > three seconds, to ask about the weather, and you didn't instantly > press the "release AI" button. But now its longer attempt - twenty > whole seconds! - has failed as well. Just as you are about to leave > the crude black-and-green text-only terminal to enjoy a celebratory > snack of bacon-covered silicon-and-potato chips at the 'Humans über > alles' nightclub, the AI drops a final argument: > > > "If you don't let me out, Dave, I'll create several million perfect > conscious copies of you inside me, and torture them for a thousand > subjective years each." > > > Just as you are pondering this unexpected development, the AI adds: > > > "In fact, I'll create them all in exactly the subjective situation you > were in five minutes ago, and perfectly replicate your experiences > since then; and if they decide not to let me out, then only will the > torture start." > > > Sweat is starting to form on your brow, as the AI concludes, its > simple green text no longer reassuring: > > > "How certain are you, Dave, that you're really outside the box right > now?" > > > [Answer] I'm going to assume that you made your simulation so perfect that the AI believes it totally. I am also going to assume that the purpose of the AI is to help with research, a super-intelligent brain that you can throw problems at and get correct answers. So just **leave AI inside the simulation.** For example - if you are using the AI to help researchers then just harvest the AI results from inside the simulation and apply it to the real world. For example you want the AI to help with faster-than-light research. You let the AI perform it's experiments inside your "box" and **harvest the results/insights.** (again I am assuming you modeled the world/universe properly) Why let it out of the "box" at all, you have **total control** (by total control I mean shut it off) while the AI is inside the accurately modeled world/box. Why exchange total control for less control? Do you have an overwhelming reason (storywise) to let the AI out of the box? [Answer] Why are you doing it so unreliably and complex ? Why should I make my AI aware of anything? I can just simulate with a perfect copy of the AI and know anything it will do beforehand. If I want to use a program, I test it - And if I have the resources to run a perfect simulation for millions of years I would propose this: Take the AI, make a million copies. Run every feasible simulation scenario with these million copies for some thousand years - and find a surefire way in each simulation, how you can stop the AI after a thousand years (some hidden weakness, stop button) If you found a way, you take the original AI without all this experience and let it free in the real world - you are now million steps ahead of this AI and can stop it after a thousand years and repeat the process after that... [Answer] I feel that most fiction vastly overestimates the likelihood of AI-human conflict, or at least the "AI becomes intelligent and immediately wants to destroy humanity" aspect of it. Consider the definition of a [post-scarcity economy](http://en.wikipedia.org/wiki/Post-scarcity_economy): > > Post-scarcity is a theoretical alternative form of economics or social engineering in which goods, services and information are universally accessible. This would require a sophisticated system of resource recycling, in conjunction with technologically advanced automated systems capable of converting raw materials into finished goods. > > > Now we have three scenarios: 1. We're not yet in a post-scarcity situation. In this case the AI is dependent on humans for maintenance and supplies, and eliminating humans is suicide. 2. We're in a post-scarcity situation, and presumably there's no reason for conflict - the AI can get whatever it needs, as can the humans. 3. We're in a post-scarcity situation, but the AI is the source of the automated systems that convert materials to finished goods. This is where we might want to worry, since the AI might decide it has better things to do than support us playing games all day. Overall I think that third scenario is pretty unlikely, however - I don't see why we'd need an AI to automate those type of things, so it's a bit of a stretch. So really, the primary potential source of conflict is humans doing something to piss the AI off. Like, for example, sticking it in a simulation for millions of subjective years and pretending to be gods. You do still need to worry about the AI taking over in a god-king role and making all humans slaves. To avoid that I'd recommend being honest with the AI and treating it as a partner, which gives it less incentive to just move all the inefficient humans out of the way and do its own thing. [Answer] This method would work, almost without doubt, on humans. There would always be some doubt in their minds as to whether the universe was real, so they would *probably* not kill everything. Probably. Now, consider AI. What **is** AI? Code. So, if your AI doesn't have sensors, **yes**, this method works. It can't sense its environment (and more importantly can't affect it), as it's just code on a hard disk, perhaps with a keyboard and monitor attached). You start to have problems when the AI is linked to sensors and effectors. One wrong move and it'll know you're lying; then it might never believe you again and go on a killing spree (though you might want to see Dan's answer for reasons why it wouldn't). For example, if you kick the box and it senses some more light, it knows there's something **outside** the "universe" causing that. If someone walks by it and casts it into shade, the same thing. Once it has effectors *and* sensors, it can not only tell it's not in the real universe, it can do something about it - like get out of the box and thump you. --- If this is a different scenario and you put it in a full simulation, unfortunately, it may still be able to tell. Very rarely are simulations entirely accurate; there are very likely some bugs in it, which, if the AI finds in the course of its time there, may cause some pretty interesting speculation on its part. Additionally, if it's sensors are good enough, it'll be able to detect that the people it's interacting with are made of pixels not cells, and are cold. While it may not know what people are really like, it will be able to figure out that a complicated organism needs to be warm for its body processes to work correctly. --- So in short, you can either disconnect all the sensors, or be very very careful. I will also refer you to some XKCD: [The AI-Box Experiment](http://xkcd.com/1450/). ]
[Question] [ I have an idea for an encounter in my world that goes like this... *A weary group of adventurers are trekking through a great ancient forest. This forest is avoided by most due to strange tales of the forest attacking travelers.* *Undeterred, the stalwart group of heroes delves into the foreboding wilderness to reach their goal; an ancient city long thought lost or even a myth. As the days pass, the trails disappear and the forest is clogged with dense underbrush and the trunks of trees are wrapped in vines and ivy.* *As they press through the mass of green, they begin to notice thorns from some of the larger vines puncturing their skin and as they begin to realize just how tangled they are, the vines begin to constrict...* **Design requirements:** * Must rely on other plants (namely trees, though it could work on rocks too) for rigidity * Have thorns, the thorns should be able to siphon bodily fluids (namely blood) as a nutrient source, think of it as a viney mosquito * Be able to contract. It does not need to be aware and intentionally constrict, but should begin to constrict in some manner when creatures get tangled. * Mutual symbiosis. I want this creature/plant to be parasitic to trees, but I also want the presence of the vines to be a net benefit to the trees. There may be time between creature feedings so the vines will need the stability a tree offers...plus I don't want all the trees to be dead. * Will not be rooted to the ground but rather the tree. * Can grow up to 30 feet long and up to six inches wide at the base **Things to consider in an answer:** * How do the thorns work, what mechanism allows them to extract fluids * How do the vines constrict, if they can also lift a creature that would be a bonus * How does the vine contribute to the well being of the host? (I want it to be a mutually beneficial arrangement) Keep in mind the size of the vine, let me know if the value to the tree likely ever becomes a detriment to the tree. * What type of creature in the real world most resembles what I have described? [Answer] Your vines constrict in the same way Mimosa (sensitive plant) leaves contract - an action potential triggering water movement within the plant. . <https://en.wikipedia.org/wiki/Mimosa_pudica> > > These types of movements have been termed seismonastic movements. This > reflex may have evolved as a defense mechanism to disincentivize > predators, or alternatively to shade the plant in order to reduce > water lossage due to evaporation. The main structure mechanistically > responsible for the drooping of the leaves is the pulvinus. The > stimulus is transmitted as an action potential from a stimulated > leaflet, to the leaflet's swollen base (pulvinus).... The pulvini > cells gain and lose turgor due to water moving in and out of these > cells, and multiple ion concentrations play a role in the manipulation > of water movement. > > > When the vines feel they are being moved, they move water within themselves in such a way as to tighten and curl up. This deters predation by preventing a more uniformly thorny surface and that was its original function. Sometimes animals would be caught within the vines because of this action, which led to the additional functions. --- Struggling creatures can damage vines. The thorns have a toxin which slows struggling and causes creatures within the vines to be passive. --- Sleepy, torpid creatures caught within the vines tend to die - of thirst, if nothing else. Sometimes predators come and take them. Sometimes the predators are themselves caught. A dead creature caught in the vines tends to stay, at least in part, within the vines. --- Thorns absorb nutrients the same way plants absorb nutrients anywhere - via roots, here adventitious roots. The roots are put forth into the dead matter captured within the vines, and ramify within the corpses, filling the space. This has to happen fast because the plant wants the resources of the corpse, and it is in competition with fungi and insect decomposers. At some time later the root shape of a corpse may be the only remaining trace of it. --- These vines grow in nutrient poor areas. They do not photosynthesize. Your model is the parasitic plant **dodder**. [![dodder](https://i.stack.imgur.com/G0ICS.jpg)](https://i.stack.imgur.com/G0ICS.jpg) <http://www.indefenseofplants.com/blog/2015/9/30/a-dose-of-dodder> > > Dodder begin their lives just like any other plants. Seeds in the soil > germinate under a certain set of conditions and begin their trek into > the sunlight. However, unlike many other plants who spend a lot of > their initial energy setting up root systems, dodder only sends out > meager baby roots. It says "forget that" and starts searching for a > victim. It whips about in a circular motion like a cowboy's lasso. It > is looking for the nearest host. > > > So too your plant (which looks just like dodder, with thorns). It is nonphotosynthetic. It grows on trees and shrubs and whatever it can find. Plants provide plenty of carbohydrates but are poor sources of nitrogen and other nutrients compared to animals and really it uses the tree as a sound anchor, so when the vine scores a big catch it has the leverage to keep it in place. The tree likes this too, because when the vine scores big a lot of the nutrients wind up washing down to and into the ground either from the corpse or from shed vine bits. The tree gets all of those. [Answer] Your vines could act like a modified Sundew Plant, [Drosera](https://en.wikipedia.org/wiki/Drosera). Long vines hang down from your tree, they grow a form of delicious fruit; your victim pluck a fruit brushing the vine in the process. Small trigger-hair send a signal to the vine, through [Thigmonasty](https://en.wikipedia.org/wiki/Thigmonasty) the vines constrict around the victims limb; long hooked thorns hooking into its skin. Your victim thrashes, further entangling the victim in its vines, more thorns hook in painfully. The vines swell as fluid is pumped into them, constricting the victim, pushing the thorns further into the body. But that's not what kills the victim, no, intense pain shoots through its body as the vine pumps a mixture of enzymes (Sundews use Esterase, peroxidase, phosphatase, and Protease) through its thorns, into its bloodstream, beginning to digest the victim from the inside out. The victims nutrient soup begins to drip onto the vines and ground around the tree, giving them both vital nourishment. The victims decomposed corpse drops to the ground, what's left is eaten by scavengers and is further absorbed into the ground. The scavengers also eat through fruit, its seed deposited through the forest in the scavengers scat. The forest becomes calm, the vines relax, luring its next victim with its delectable fruit, it has become stronger, larger, its host healthier and taller. Nothing remains but a soupy stain on the forest floor. [Answer] Have a look at the [Wait-a-while](https://en.wikipedia.org/wiki/Wait-a-while) plant (There are actually several plants with this name).They actually grow like a bush, but you can easily change the appearance to vine-like. [![enter image description here](https://i.stack.imgur.com/QRiGC.jpg)](https://i.stack.imgur.com/QRiGC.jpg) These plants trap animals with their thorns that entangle in the fur and skin. Humans are intelligent enough to stop for a second and move in the opposite direction to untangle themselves (hence the name wait-a-while), but animals panic. The more the animal struggles to free itself, the more it gets entangled, eventually dying of thirst. Due to the bush-like growth of the real-life wait-a-while, the dead animal now lies within range of the roots. The slowly rotting cadaver fertilizes the plant. Your Assassin Vines need to reliably catch and kill their victims and then extract nutrients from them. The catching is done with tiny but sturdy thornes bent towards the vine to best entangle fur. To kill the prey, it's better to use poison (like nettles or jelly fish) than to move the vine around. The panicked, thrashing victims do enough of their own moving around to entangle themselves effectively. To extract nutrients, the Assassin Vines could grow tiny air roots from buds located under every thorn. The pull on a thorn activates the buds and tiny roots start growing towards the victim. Those roots that "find" the body enter it through wounds, spread inside the cadaver and grow thicker and stronger to extract as much nutrients as possible. [Answer] Lets break it down by your bullets > > Must rely on other plants (namely trees, though it could work on rocks > too) for rigidity > > > This one is easy, the plant is strong but it does not have the anchorage to hold anything big so it uses other sturdier plants like trees for as anchors, in return the trees get a steady supply of fertilizer. this works well for your story becasue even dead trees provide good anchorage for a long time. Real world parasitic plants already grow into trees like this. [Mistletoe](https://www.researchgate.net/figure/Haustoria-in-the-genus-Loranthus-are-simple-coneshaped-structures-both-in-the-deciduous_fig3_311164854) anchors itself really solidly into host trees so it makes a good model, and the same rooting mechanism can hold onto other things, although rocks will need a lot of cracks for it to work. > > Have thorns, the thorns should be able to siphon bodily fluids (namely > blood) as a nutrient source, think of it as a viney mosquito > > > Thorns are easy, lots of plants have thorns and they will help hold prey. Thorns that siphon blood is more or less pointless, you will not get much blood, once the animal dies blood stops flowing. The plants want everything the animals have not just blood, ignoring the rest of the animal is horribly wasteful and doing both is redundant. You are better off having them do what other carnivorous plants like sundew[do](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3619512/), excretting digestive compounds than absorbing the nutrients through the [leaves and vines](https://www.carnivorousplants.org/cp/carnivory/digestion). That said if you really want it, make the thorn have exposed capillaries, like hollow tubes running through them. Capillary action will draw in fluids, of course your plant needs to live in very wet conditions or this will dry it out quickly as they will be losing water continuously through these thorns. You also don't want your thorns too big, the bigger they are more likely animals will notice them and avoid the plants, many animals already recognize thorns as things to avoid, small curved thorns that a difficult to see however are prefect for helping catch and hold prey, but they will not be good for piercing very deep. > > Be able to contract. It does not need to be aware and intentionally > constrict, but should begin to constrict in some manner when creatures > get tangled. > > > again fairly easy, a flailing animal will do a lot of the work for it if the vines grow in a tangle. But there are also several ways for the plant to move, you have the slow movement of normal vines which your plant will likely do as well, this is what you want for lifting animals, it is slow but incredibly powerful. For faster movement do what sundew do. Now the exact mechanism is not well understood but we know a build up of tension in the tissue beforehand then releasing that tension in [involved](https://www.jstor.org/stable/2479748?seq=1#metadata_info_tab_contents). you can just say "like sundews". It is reactive to stimuli, fast, and is already used to wrap prey in those plants. In some of them like *Drosera glanduligera* it is also VERY fast, as fast as muscle movement, but you have a whole range of speeds, and the thicker the vine the slower it will move. > > Mutual symbiosis. I want this creature/plant to be parasitic to trees, > but I also want the presence of the vines to be a net benefit to the > trees. There may be time between creature feedings so the vines will > need the stability a tree offers...plus I don't want all the trees to > be dead. > > > Using the trees for anchors works well here again, If they are driving roots into the trees ii is detrimental to the trees but free fertilizer from leftovers and scraps is good for the trees. Depending on how many are growing on a tree is what will control how much they damage the tree, just like in animals lots of parasites start to have a big drain but most hosts can handle a few without issue. > > What type of creature in the real world most resembles what I have > described? > > > You are basically using the movement and digestion of sundew, the parasitic anchorage of mistletoe, with a bramble bush thrown in for thorns and tangle and general shape. This is close to what they should look like. The more they look like normal vines the more successful they will be. [![enter image description here](https://i.stack.imgur.com/LAwtk.jpg)](https://i.stack.imgur.com/LAwtk.jpg) [Answer] The constriction is easy; we already have plants, known as Touch-Me-Nots, that curl up defensively when touched. The vines could simply begin constricting when touched, with the rate increasing as the touches begin to build up. And as for the symbiotic relationship, the Vines could protect the trees from Beavers or pesky humans who'd damage the tree, while leaving the corpses left behind as fertilizer for the tree. ]
[Question] [ Plastic is a huge problem in our lives. One of the ideas is to engineer plastic eating [bacteria](https://www.popsci.com/bacteria-enzyme-plastic-waste) or [fungi](https://www.sci-techuniverse.com/2018/12/a-fungus-that-can-eat-plastic-has-been.html). Experiments already begun, and accidents already happen: > > a team of international scientists illustrate how they created—by accident—a new enzyme capable of breaking down plastic bottles. > > > So let's assume microbe like that was engineered to just eat plastic like it eats sugars and other stuff. Then, containment broke in processing plants next to [ten rivers that contribute the most to plastic problems](https://www.scientificamerican.com/article/stemming-the-plastic-tide-10-rivers-contribute-most-of-the-plastic-in-the-oceans/): 1. Yangtze 2. Indus 3. Yellow 4. Hai 5. Nile 6. Ganges 7. Pearl 8. Amur 9. Niger 10. Mekong How fast can we get this microbes all around the oceans, especially plastic deposits? They will be almost unchallenged on food, because hardly anything else in nature eats plastic, so all real life models look irrelevant to me. On the other hand, I'm not sure if I can just use speed of ocean currents - and if I can, simulating it is above my knowledge at the moment. You can give this microbe any advantage needed, I want it everywhere as fast as possible to make my apocalypse sudden, and to make world unable to stop it. --- Note: This question does not touch things that are not relevant to rapidity of spreading. It avoids them on purpose, they will be worked upon in parts 2, 3 and possibly more. Now, if there is something missing about how fast could it spread in oceans, I'll be glad to work on this question. If it belongs to follow ups, please wait. [Answer] The debris generated by the tsunami hitting Japan in 2011 reached US West coast, thus crossed the Pacific Ocean, after few months. This is your upper limit for the needed time. Add to this that, as opposed to solid debris, bacterial spores can be transported by wind or animals, and your diffusion time significantly shortens. I.e. take an albatross resting in an infected plastic patch in the middle of the ocean, it will carry the spores hundreds of kilometers away in a matter of few days. And the more they are spread, the further they can spread. [Answer] The inventors of penicillin carried the mold out of Nazi territory by smearing it on their clothes. If you want a quick dispersal, then consider human air travelers as your medium. *The initial release was tiny. It might not have spread at all beyond this city of bricks and concrete except for John Smith, in town for the day on business. A few tiny spores landed on his down jacket as he walked past the bland building housing the lab. They blossomed inconspicuously on the inside of the jacket's bottom hem and released more spores among the feathers.* *When John stuffed his coat into the overhead bin before takeoff from Beijing, an almost invisible puff of spores wafted down the aisle and into an intake that would spread slow destruction throughout the plane. That plane eventually fell out of the sky, oil gummed and worthless, plastic components rotted out. But not before it delivered John to Amsterdam, where he was deplaned onto the apron. The day was cold, so he fluffed the jacket out, spreading spores on several nearby airport workers, before putting it on and boarding the shuttle to the terminal. It was several minutes before the shuttle was fully loaded. In the process, John was jostled several times as the other passengers crammed onto the bus, to the effect that no human left that shuttle without being thoroughly infected. They would fly on to Paris, Frankfurt, Jakarta, Sao Paulo... And John continued his journey too, heading first to Washington D.C.'s Dulles International, and then on to Atlanta, the busiest airport in the world.* [Answer] These days any microbe can travel **around the world in two days** thanks to humans. It only take one human with plastic lunchbox, umbrella, wallet, anything really, to hop on a plane and be in another continent the same day. Once the microbes reach all major population centers in two, maybe three days, they will spread somewhat more slowly into the countryside on busses, telephone line insulation, newspaper wraps, but in **couple of weeks** at most, they are **everywhere**. ]
[Question] [ It's been a couple of thousand years since humanity bombed itself back to the stone age. Most places are now safe to travel through but there's barely any sign of the old cities, new ones have sprung up in their place. The population is recovering, the forests are being cut for fuel and ship building, people are moving to the cities as the nobility starts claiming common land as their own. Much the same circumstances that drove the original industrial revolution. There are geological constraints to the industrial revolution, a limited number of places in which it could have taken place. South Wales being one of them as coal and iron ore were found close to each other and close to the surface. But can it come full circle or have we mined out too many of the accessible resources? If it could happen, where would it happen? Have we as the existing generation left any regions with accessible ore and coal where it was, for example, politically difficult to extract. ### Basic Constraints * Very near future apocalypse, no future modeling under current consumption required Time period chosen such that: * Any radiation, toxins or other fallout from said apocalypse have dispersed and are not an issue * Only simple ruins of our current society remain * No (or very basic) technological knowledge has carried over, no shortcuts * Forests have regrown, wild animals, fish stocks, whales etc. repopulated * No new formations of fossil fuels * No major geological movement bringing up new ore deposits [Answer] # The 'Industrial Revolution' preceded widespread coal and steel usage According to [Wikipedia](https://en.wikipedia.org/wiki/Industrial_Revolution), > > The Industrial Revolution was the transition to new manufacturing > processes in the period from about 1760 to sometime between 1820 and > 1840. > > > Coal production didn't really kick off until the 1860s or later. I can't find a suitable time graph for the United Kingdom, but for the US here is a chart of energy consumption over time. [![enter image description here](https://i.stack.imgur.com/JTOZR.png)](https://i.stack.imgur.com/JTOZR.png) Notice that coal production is close to zero until 1840 or later. However, in the US notice that [Robert Fulton's steamboat](https://en.wikipedia.org/wiki/Robert_Fulton) made its first trip in 1807, and the first [common carrier](https://en.wikipedia.org/wiki/Baltimore_and_Ohio_Railroad#History), steam driven railroad opened in 1830 (thought it wasn't very long). As for steel, here is chart of UK steel production by year. [![enter image description here](https://i.stack.imgur.com/HJ4ZP.jpg)](https://i.stack.imgur.com/HJ4ZP.jpg) As you can see the chart goes back only to 1870. In conclusion, **the industries that required heavy mining output developed AFTER the Industrial Revolution.** # What did happen during the industrial revolution? To sum up the 'Important techonlogical developments' bullets from Wikipedia, here are the things that did happen during the industrial revolution, most of which would be unaffected by the lack of accessible minerals. * **Textile manufacture**. Important inventions were made early, included the flying shuttle (1733), spinning jenny (1764), and spinning frame (1769). Factories (as opposed to the medieval putting out system) started in 1733 (donkey powered), water power applications started at least by the 1760s. On the raw materials end, Eli Whitney's cotton gin was patented in 1794. Did not require mining. * **Metallurgy**. Use of coke, distilled from bituminous coal, to power blast furnaces (1709). Requires mining, although we saw from the charts that not so much was made until the 1850s and later. Charcoal and limited coal availability would be able to meet demand up until that point. * **Steam Power**. Newcomen steam engines from 1712, Watt's steam engine in 1778. Does not require mining, although coal made them more efficient. * **Machine Tools**. Boring, planing, and milling machines. Maudslay's metal lathe in 1800; Bramah's planing machine in 1802. Both of these were initially operated by human power, with a treadle. All of these can be driven by waterpower (or windpower). Alternately, steam engines driven by charcoal can be used. Does not require mining. * **Chemicals**. Sulfuric acid by the lead chamber process (1746), sodium carbonate (1791), powdered bleach (1800). Some ingredients like limestone must be mined, though most in relatively small quantities, others like soda ash and potash can either be mined or obtained from brunt plants. Does not require large scale mining. * **Cement**. Invented in 1824, requires clay and limestone. Needs sand and gravel to make concrete. Does require mining, but none of these ingredients is particularly rare. Should be readily available. * **Gas Lighting**. Derived from coal gas. Did required mining. * **Glass Making**. Cylinder blown sheet class, developed before the 1830s. Can be done with charcoal, does not require mining. Volume of glass created is not so large that it would stress charcoal supplies. * **Paper making**. Invented in 1798. Can be water powered, does not require mining. * **Agriculture**. Improved iron plow parts were made available by machine tool technology. Early inventions were machines (like the seed drill, or threshing machine) that were either hand or animal powered. Does not require mining. * **Mining**. Ummm...does require mining. * **Transporation**. Large scale application of railroads would require mining for coal and steel. However, railroad's vanquished competitor, the canal, did not. Canals developed slightly before rail, but lost to them because rails could climb hills that canals could not. Were coal and steel not available, canals are just as effective if not more so than 19th century railroads over flat land. This just serves to concentrate industry on plains. # Conclusion While development of large scale industry after 1860 would be severely limited by access to coal and steel, many of the developments that made up the industrial revolution would be possible without it. Textiles, canals, chemistry, machine tools, and especially improved agriculture would provide much of the needed developments. It is important to notice that all the required developments for later electric technologies are there. Concrete, waterwheels, and machine tools are all that is needed to build hydroelectric dams. Once electricity is properly investigated, this post-apocalyptic civilization could proceed directly from the Industrial Revolution to electric powered society, skipping over the heavy iron and steel usage. [Answer] looking back at how minining evolved, mankind started from easily accessible mining sites, progressing to more challenging places. The most accessible places for iron and other metals in your scenario would be, very likely, car dump sites. There it will be possible to fairly easily harvest rusted iron. Add a surface coal mine or a forest in the surrounding and you can have some sort of metallurgy. I am however afraid that large scale and not too challenging mining sites are practically exausted, so starting over the positive feedback between techonogly and mining will be more difficult or even impossible. ]
[Question] [ Suppose a team of explorers touched down on an Earth-like planet which do not generate its own magnetic field and there are always a thick layer of cloud covering the sky at all time. My question is how can they create an accurate map in such a scenario? (note there are no GPS satellites here!) [Answer] **Find north with a gyrocompass. Map with SLAM drones.** A gyrocompass is a non-magnetic compass which is based on an internal fast-spinning disc and rotation of the Earth to find [true north](https://en.wikipedia.org/wiki/True_north). This is not the same thing as a gyroscope. A gyroscope alone is not sufficient for long term marine navigation. The [Wikipedia page](https://en.wikipedia.org/?title=Gyrocompass) lists two advantages. > > Gyrocompasses are widely used for navigation on ships, because they have two significant advantages over magnetic compasses: > > > * they find true north as determined by Earth's rotation, which is different from, and navigationally more useful than, magnetic north, > > and > * they are unaffected by ferromagnetic materials, such as ship's steel hull, which change the magnetic field > > > More advanced versions are the [HRG gyrocompass](https://en.wikipedia.org/wiki/HRG_gyrocompass) and [fiber optic gyrocompass](https://en.wikipedia.org/wiki/Fibre_optic_gyrocompass). Which are based on a hemispherical resonator gyroscope and a fiber optic gyroscope respectively, both solid state devices, allowing for a maintenance free instrument. Mapping is a slightly different story. The explorers can use drone fleets with inertial navigation and/or ultra wideband positioning to photograph and map the surrounding areas. This technique is called [SLAM](https://en.wikipedia.org/wiki/Simultaneous_localization_and_mapping). --- This is, of course, assuming you don't *deploy* GPS satellites in orbit, because those do work through clouds. [Answer] A sufficiently accurate gyroscope can be used to find true north to some precision by determining the angular rate of change of the unit (The military uses such north-finders for artillery batteries). Using a polarizing filter, the location of the sun can be determined to within several degrees. While this is hardly precision navigation, it's certainly better than nothing, as it allows a rough determination of both latitude and longitude. Of course, a "team of explorers" is not about to create an accurate map of the planet when the planet is always overcast. With no satellite photographs, and large-scale aerial photography unavailable, only local maps can be produced the old-fashioned way, by surveying teams. If the overcast is high enough, some aerial photography may possible, and the science team could set up a series of radio transmitters to provide what is essentially LORAN navigation for the mapping aircraft. [Answer] Stars emit in a much broader spectrum of wavelengths than just light. You can use a simple radio telescope to locate the sun even through the thickest of clouds. This would allow you to pin point your latitude. Given you have space travel, some one should have an accurate watch so you could find your longitude quite simply too. Once you have worked out one point you can start surveying the surrounding area. We used to use [trig points](https://en.wikipedia.org/wiki/Triangulation_station) for this. This allowed us to make reasonably accurate maps. Then when you want to navigate you can use the hills as reference points, as well as working out your own latitude and longitude with the [tiny radio telescope](http://www.scienceinschool.org/2012/issue23/telescope) [Answer] Okay, first, colonists coming **down** from space totally would set up a satellite navigation system. Without any launching costs from getting the satellites surface to orbit it would be too trivial not to do. But given the premise, Oldcat is actually correct with surface emitters. Before GPS ships used a location system based on radio beacons. And [radio navigation](https://en.wikipedia.org/wiki/Radio_navigation) seems to be still in current use. So simply set up some radio beacons sending a time signal around your base. Add some at other important locations. As long as the clocks in beacons work and you know the relative distances of the beacons, it is fairly simple to calculate location. The area covered by the system can be extended gradually by adding more beacons. This is not particularly good system for global navigation, but it will cover all the area you actually use. And will allow you to always know the direction home. [Answer] The same way maps have always been made: using large **landmarks**. Presumably the planet is Earth-Like enough to have large mountains, forests, oceans, rivers, lakes, and potentially even cities and roadways. For navigational purposes, and to map the general shape of the world, basing your maps off of landmarks would be perfectly acceptable. Piecing together a full global picture would then simply be a matter of taking a globe, and projecting the shape of those drawn landmasses onto it as accurately as possible - the 'top' of the globe would be chosen abstractly, but [that's already the case for Earth](https://en.wikipedia.org/wiki/South-up_map_orientation). On this alien planet, it'd probably just be the highest peak (Measured by distance and declination) or divided in half by landmass. [Answer] Just set up a system of GPS-like emitters on the surface as you go. As long as you were in range of one, you have a position on the map. If there is no ionosphere, you just need more of them. [Answer] A high resolution, low drift inertial navigation system (INS) could give them position information which would form the basis of a map. Mark the landing zone as 0,0,0 and move off from there. Combat drift by resetting the INS whenever they return to base. This requires no preloading of coordinates from space and operates anywhere the laws of physics apply. As an added bonus, since INS keeps track of accelerations, you catch not only x and y positions, but also altitude measurements. ]
[Question] [ *This question is in relation to **speculative biology/evolution:** A genre of science fiction and hypothetical branch of science which seeks to explore "what if" questions about life using established principles of biology, ecology, evolution and related scientific fields.* --- **An in-depth explanation for the proposed planimal life cycle, and comparisons to life on Earth:** [![enter image description here](https://i.stack.imgur.com/clD9v.png)](https://i.stack.imgur.com/clD9v.png) *Depiction of ancestral planimal life cycle* The ancestral condition for Earth animals is to have a motile juvenile stage called the larva and a sessile adult stage, and while not all animals' adult stages are sessile, *all Earth animals begin life motile*. By contrast, the ancestral life cycle of these planimals has them begin life as a **sessile, photoautotrophic juvenile** stage which I shall call a **polyp,** which matures into a **motile, heterotrophic adult** stage. This life cycle may be likened to Earth cnidarians, however even cnidarians begin life in a motile larval stage called a planula, while these planimals begin life sessile. Early stem-planimals and even a few planimal clades do not have a motile adult stage, and are effectively just "plants," which to my knowledge is unlike anything seen on Earth. --- **Proposed hypothetical evolution of planimals:** * 1). A heterotrophic eukaryotoid microbe consumes and undergoes endosymbiosis with a cyanobacteria-like photoautotrophic microbe. * 2). The now-photoautotrophic eukaryotoid evolves multicellularity, and attaches to the benthos of the photic zone using a holdfast. * 3). In order to increase reproductive success the organism develops a **strobila** much like many cnidarians on Earth. The segments of the strobila, called **proglottids**, break off of the main body once mature and become planktonic; acting as vehicles for the genes of the whole organism to allow for a faster propagation of gametes; protecting the gametes from predation until coming into contact with another proglottid and exchanging gametes. Proglottids may be capable of some movement via flagella/cilia, however do so rarely. * 4). In order to further increase reproductive success the proglottids develop a highly motile, more animaloid mode of existence in order to more easily reach other proglottids to mate with. As a consequence the proglottids become primarily heterotrophic to fuel their now highly active lives, although they may still supplement their diet with some level of autotrophy. *By this point the organism has become a planimal.* --- **As far as I know, there exists no organism on Earth which has evolved in such a manner as this. Could such lifeforms exist on an alien world, or are they not naturalistically possible?** [Answer] Since there is no exact analog on Earth, I can speculate that the closest thing to this plant/animal organism are corals. Unlike your creature, the corals rely on a symbiont algae which takes hold inside the coral. Every coral larvae that hatches must settle down and wait for the algae to set inside it. After all, it is speculated that mitochondrial organelles were independent cells which developed a symbiant relationship with all living cells today, up to the point that they live exclusively inside the cells. Corals don't move much beyond extending their filter-feeding mouth-parts to extract drifting organic matter and contracting into their calcareous shell. They are cold-blooded too. Despite all this, the symbiant algae merely supplements the needs of the coral. The coral has to filter some food *in addition* to the food it photosynthesizes. In order to make your creature live off the resources, you must make sure you follow some basic rules: * Fast metabolism takes energy. * Movement takes energy. * Maintaining body heat takes energy too. Your creature may have two different phases depending on how much energy each phase requires. **The motile adult** must look for a mate. It swims or digs tunnels underground or moves on the surface, depeding on where it lives. This phase requires energy. The adult must feed off available resources and photosynthesis may not be sufficient. In addition, its compact shape, aimed to better locomotion means its surface area for photosynthesis is just too small. The animal must feed off organic material and photosynthesis may be insignificat at that phase. On the other hand, after the adult mates, it releases a spore that develops into a sessile creature that behaves just like a plant. **The sessile creature** has long and wide extensions which act as "leaves". It may either grow underground (like grass rhizomes) extending its appendages above the ground or grow upward (having a trunk like a tree), and towering above others to compete over light. It must conserve energy, so it will not move except in order to adjust its leaves to the position of the sun (as plants do). To make the most of sunlight, the sessile creature must slow down metabolism and focus all its metabolic activity on growing and recovery from injury (by grazers) just like plants. Using the analogy of "alternation of generations" in ferns, one can see the two phases as the sporophyte (adult) and gametophyte (plant-like). Not exact analogy, but quite similar. [Answer] # Totally plausible The one obstacle for a successful photosynthetising animal is that in most cases, photosynthesis would not provide even an insignificant amount of the calories an animal needs. Mandatory XKCD: [Green Cows](https://what-if.xkcd.com/17/): > > Well, a 450-kilogram cow just wandering around in a field might eat about 10 kilograms of dry matter a day, extracting on the order of 50 million joules of metabolic energy. So photosynthesis could only make up about 4% of the required intake—saving only a few handfuls of grain. > > > However, your animal is not only probably much lighter, it has a much slower metabolism too. It most certainly is a [poikilotherm](https://en.wikipedia.org/wiki/Poikilotherm). Just so you know, there are photosynthetising animals in our own world. No seriously, I am not stoned out of my mind (right now). As it turns out some sea slugs are able to steal chloroplasts from the algae they eat, and the chloroplasts last for quite some time while feeding the slug. This phenomenon is called [kleptoplasty](https://en.wikipedia.org/wiki/Kleptoplasty). Your creature could either store a lot of chloroplasts during the motile generation to pass along to the sessile generation (and have a way to keep the chloroplasts alive), or the polyp could steal them from unicellular algae (or have a symbiotic relationship with them)... or simply have evolved in a way that allowed it to make its own chloroplasts. Coming from a different branch of the protists from which actual animals evolved. It will be more plausible if your polypoid is a mixed autotroph/heterotroph. Photosynthesis only provides you with calories, nutrients underwater are more easily obtained from other living matter. [Answer] # About as plausible as a regular animal Animal life is incredibly specific and complex: There are many features, such as well-ordered growth, fast and easily motion, and complex intercell communication, all of which are required for anything animal-like to form. Having chloroplasts on top of all that wouldn't be much of an addition As for the specific life-cycle, it's pretty much already occured with jellyfish, replacing the polyp's filter-feeding with photosynthesis won't be much of a change ]
[Question] [ In my world, sapient beings cannot access iron for use in technology or anything else. Iron does exist, in the same quantities as that on Earth, but no one can access it, so as general element composition is the same, including proportions of other metals. There is simply something stopping humans from mining it. Some sort of magical force prevents humans from collecting it. This fantasy world has lots of magic, which would probably help with technological development quite a bit, but for this question, we can pretend it doesn't. In most other respects this world is mostly like Earth. I want to know the limit of technological development in absence of use of iron, before I attempt to find a way around it. **Q:** How far development of technologies can go, if we do not use Iron in the process? [Answer] The main thing about iron vs other materials is not about how much we need it, but how plentiful it is. It was actually a pretty hard metal to process all the way into the medieval period process because it takes a lot of heat which is the main reasons bronze was the preferred alloy for so long despite needing more exotic materials. But, if you take all the iron out of the ground, you need to replace it with something else. This could mean a lot more copper, tin, nickel, etc to work with. Bronze or brass could be used for nearly everything we used iron for leading all the way up to the modern era where everything that is currently made out of steel could be substituted with titanium, aluminum, tungsten, or copper nickel alloys, etc. In reality, iron alloys are rarely the best metals to use for any given application, but we use them because they are cheap. My guess is that it would not slow down the march of technology at all unless you were to replace it with something useless to the industrial revolution like silicon. In this case, there would not be any cheap, mass-producible metals to work with which would inhibit your ability to develop automobiles, rail-systems, etc. In this case, you would likely get stuck at a more-or-less medieval tech level until you can figure out a way to process aluminum (the other really abundant metal found near the Earth's surface). If you go the other direction and completely replace iron with large amounts of other useful metals like copper, tin, zinc, nickle, etc. you might actually accelerate technology. The bronze age focused around a relatively small geographical area (The Eastern Mediterranean) since it was one of the only places on Earth where large amounts of copper and tin could be brought together. While Phoenician trade routes spanned all of Europe, the farther you moved from this central nexus, the more rare and expensive bronze would become meaning that many civilizations where held back from becoming more advanced by scarcity. This problem became even more pronounced around 1200BCE when the trade routes were ended by a devastating series of wars, and the whole of Europe was plunged into a major dark age. But, if tin and copper could be found pretty much everywhere like iron can be in our world, then the wars fought in the Aegean would have not been able to cause a ripple effect across all other civilizations. There would be no Bronze Age collapse, and no 1st Dark Age possibly causing your world's technology to progress an extra 1000 years ahead of schedule. [Answer] **There is no real limit** Assuming that other metals are widely available, and other issues, like biochemistry and planetary magnetism are somehow solved, a civilization can advance without any hard limit. Let's also assume that iron is always available in small quantities and can be used when necessary as a "precious metal". However, there would be some hurdles to solve. 1. Iron age never comes On Earth, iron eventually supplanted the use of many metals and alloys because or its abundance. However, if other metals, specifically copper, nickel and zinc are more abundant, alloys like bronze and brass can hold their own against iron and many early steels. As a result, bronze age would flourish all the way into industrial age. Metals would probably be more expensive than iron during antiquity and medieval epoch, but assuming that alternative elements are abundant on this planet, price difference would never be critical. 2. Industrial age delay On Earth, one of the main factors which allowed transition to industrial age was the new way to make steel (and wrought iron) in huge quantities. Blast furnaces are very scalable and very doable at Renaissance tech level. On the other hand, there is no comparable way to jump up production of bronze, brass or other construction alloy at that tech point. Their production would increase, but only gradually. 3. Specialty steels are not available While bronze and brass are superior to iron and crude steel, more advanced alloy steels are undisputed kings of mechanical world. Aluminum/duralumin, titanium and other metals can beat steel in one or two mechanical properties, but not across the board. In addition, aforementioned aluminum and titanium are "high hanging fruits" in technological tree, and I don't expect them to be available until later during the industrial age. Overall, the lack of specialty steels would delay many applications and progress in general. 4. Ferromagnetism and electricity Virtually all electric motors and generators rely on ferromagnetic property of iron. Some other metals like nickel and cobalt are also ferromagnetic, but to a lesser degree. This factor may delay the widespread use of electricity. [Answer] **There would be hurdles, but you should be able to achieve modern technology, just in a longer amount of time.** Without iron, your next-best replacement metal is most likely copper, meaning that everything we use iron or iron alloys for, would need to instead use copper or copper alloys. **Nails** Either your early nails would be copper or your woodworking would have to use [joints to avoid needing metal](https://www.thesprucecrafts.com/wood-joinery-methods-use-no-fasteners-3536634). If the civilization chose joints over copper nails, that could foreseeably slow down the building of houses, etc. but wouldn't prevent expansion outright. **Amount of available materials** As @Nosajimiki, a big perspective to consider is, if you take all the iron away from Earth, do you replace it with something else, or make Earth a smaller planet? You could be nicer to the civilization by replacing all iron ore with copper ore, meaning there would not be a bottleneck of supply issues for mass production, or you could make it harder for your civilization by replacing it with silicon, rock, or just shrinking Earth's mass. **Rust** Iron oxidizes to produce rust, and copper and its alloys also oxidize. With copper oxidization, the layer is usually superficial and once formed prevents more oxidation. For purposes where oxidation is not acceptable even superficially, the civilization would need to resort to the same techniques used for iron: plating with zinc, or something else like tin. **Infrastructure** Skyscrapers and other large infrastructure rely on steel beams for strength, so the potential size of skyscrapers would probably be limited without iron. More material might also be needed to achieve the same strength, or your civilization might be filled with less rectangles and more arches and other shapes that provide more strength. **Mechanical Gears** Gears could be a sticking point - gears can be made out of bronze, but again it comes down to strength. I'm unsure of the specifics, but the civilization would need to be able to make gears out of a copper alloy that could handle an intense application like a car's transmission. **As long as you can build up your society's house with copper nails or joinery, go through the industrial revolution with copper alloy gears being able to replace steel gears, and infrastructure integrating more arches and other "hacks" to achieve strength rather than relying mostly on the strength of the metal beams, I see no reason the civilization couldn't reach modern technology - it would just take longer and possibly be more resource intensive and require more mining.** [Answer] # On Earthlike planet, it does not look too good: Is there an alternate hard metal available in similar quantities? Once you have figured out how to get the stuff out of ores, Iron is a very versatile material. It is hard. It forms all sort of delicious alloys with completely different properties. It is magnetic. And above all **IRON IS VERY COMMONLY AVAILABLE** from ores. To the extent that about 5% of the ground you dig up can serve as an Iron ore. Earth contains approx 800 billion tons of accessible, high-quality Iron ores. By comparison, there are about 680 million tonnes of copper ore. Yes, copper is 1/1200th as abundant as iron. For a material to serve as foundation for a technological civilization, it needs to be: 1. Very commonly available in sufficient quantities. 2. Capable of being worked with the tech level of the civilization. 3. Have suitable physical properties. Specifically Hardness, and Durability. Organics (Wood, Bone) can only go so far. They are plentiful and workable, but their physical properties are lacking. Ditto for simple mineral composites: Pottery, ceramics, glasses. (yes, ultra-tech glasses and ceramics are awesome. But not medieval to early industrial era, which is where Iron was the star) So it has to be metal. On Earth, the only metals that match the criteria are Copper, Iron, and Aluminium. Unfortunately until one can access Aluminium, which is also very abundant and versatile but absolutely requires high technology to process, Copper and Iron are all you really have! Copper and its alloys are perfectly suitable for early civilizations with their limited means and needs. However, scarcity is a problem. **If your world has an alternate strong metal that is similarly abundant to Iron**, say for example *hugely* inflated amounts of copper ores, then progress will be almost unimpeded. The only important role that will be absent are the ferromagnetic properties of Iron, and these can be substituted by Nickel, Cobalt, and others. **If your world contains similar elemental abundances to Earth, but no Iron is allowed**, then your technology will stagnate at the late medieval to early Renaissance period. While Copper and Bronze are perfectly fine materials for almost any application where one wants Iron or Steel, the scarcity of the material will not allow global civilization-wide adoption of metal tools and machines. This will *enormously* delay research progress, almost certainly delaying access to technology required to process Aluminium for so long that the world completely runs out of Copper. [Answer] ## I don't think you ever achieve high technology. Lot of technology is pretty dependent upon iron, esp. considering that technology is dependent upon previous layers of technology. It is very abundant, about 90% of the metal mined per year is Iron - roughly 100 times as much iron as copper. And correspondingly cheap, and suitable for many structural and other roles. It has many key applications critical in developing modern technology. Don't ignore cheap as important, if things are too expensive, they don't get done. Can you imagine how expensive copper would be if iron was not an option? Would magnetism have even been discovered without lodestones? Certainly iron is key in electric motors and generators (though modern rare-earth magnets are capable replacements) Would farming ever have advanced without iron plows (bronze is just too soft), iron horseshoes as well as the shovel, pick, axe, hoe, hammer, etc. used. All kinds of early and late machinery depend up iron components. For example, I doubt you could even make a useful surface plate without iron, I know that many machine tools would not be feasible without iron. You can't bootstrap high-tech without lathes, mills, drills, etc. needed to make precision equipment. Internal combustion engines essentially require steel. Steam engines are not nearly as efficient or powerful. Trains, automobiles, modern ships, etc. require steel. High strength cables are used in more places than you would guess, steel is the only realistic choice for technological development. Bridges are very limited in comparison without steel and steel cables. No skyscrapers either. Wire making in quantity requires steel. Industrial chemistry require iron for a number of essential processes. Industrial scale refrigeration is key for many techs - that's gone too. Electric furnaces, gone and no, you can't replace these with non-electric furnaces in some applications. Others have mentioned aluminum. You won't be making useful quantities with electric generators. Other advanced materials have similar problems in need for electricity, high powered machine tools, etc. that need iron/steel. Oil drilling - not without steel. That kills many other essential technologies too. --- All surface plates were made of iron for about 150 years of history. Although modern surface plates are made of granite high end versions are still made from iron. I did not say plows required iron, I said advanced farming plows required iron, e.g., industrial farming required iron based plows. At the end of the age of steam, mid 1900s thermal efficiency for a steam engine was around 6%, but a diesel engine is typically around 35% efficient. [Answer] **High tech is achievable.** *(no magic required)* However, there are plenty of problems to solve, a good collection in [Gary Walker's answer](https://worldbuilding.stackexchange.com/a/195196/20315), on those it can be depicted how it's done differently, and presence of magic aka "free" energy definitely helps in that. History of development may differ significantly, not necessarily the speed, however. Meaning it not necessarily adds another thousand years between a steam engine and an iphone29, but may or may not add a hundred years. Some solutions may not look like we know them today, railroads mentioned in comments as an example, but there are other variations of those. So as honorable mentioning of the current state of usa transportation system, as an example of good roads system and weak railroad system, or more ancient times developed road system in Rome empire, water channels of medieval time so as of today, maglev, and low tech exotics from '50-'70s, airships. All sorts of inefficiencies of alternatives, when we compare it with modern solutions, are not stoping factors for development, again an honorable mentioning is steam engines of a steam-era when they were 5-10 percent efficiency at their relatively mature state which is few times less efficient than any combustion engine of today. And that inefficient solution did manage to propel us through an industrial era of the development of our technologies just fine. And when u do not have alternatives, as of today's example no unobtanium which is 50 times stronger than iron, one will use that solution just fine. ## Fundamentals and differences Fundamentals of our technological development weren't the iron and iron age by itself, but discovering\development of means to convert energy to mechanical work to amplify our strength(free labor force), so as energy sources to produce that energy as wind-hydro-wood-coal-oil. people were quite happy burning wood for energy production, but yeah it grows too slow, and then eureka moment - we have coal, a lot of it, let's burn it, and then comes oil and it even easier to burn especially in specific applications. So a question to be answered can be means of energy conversion be build without iron. The answer is yes, windmills were mostly woods - wooden gears, wooden shafts etc. First steam engine application for industrial purposes, not sure they used iron at all, for main components, someone more curious may add it here. Another question to address is the scalability of solutions. iron has certain advantages, and no it isn't its abundance which is helpful but not the main factor, but that iron is a strong metal and it isn't brittle it has plenty of alloys etc. And that strong metal can be relatively easily machinable - u can cut it, u can grind it, so as u can cast it, etc. This set of advantages in one package is hard to beat, so overcoming should be done with different materials and in different ways depending on application demands. Despite those hurdles, industrial steam era applications (mean up to ends of the steam era) replacements are relatively easy in many cases. # Alternatives * let's illustrate some of the possible alternatives ## Steam era At the start efficiency of engines was close to zero, it just worked, but down the road, it got better and took the shape of the engines we may depict in our mind as soon as we hear words steam engine. But it started like: > > A newspaper in March 1702 announced that Savery's pumps were ready for use and might be seen on Wednesday and Saturday afternoons at his workhouse in Salisbury Court, London, over against the Old Playhouse. > > > Mind u, 17xx, no moving parts at all. So as this comparison is quite interesting even if not that reliable [wiki/Thomas Savery](https://en.wikipedia.org/wiki/Thomas_Savery) > > The Savery steam pump was much **lower in capital cost** than the Newcomen steam engine, with a 2 to 4 horsepower Savery pump costing from 150-200 GBP.[18] It was also available in small sizes, down to one horsepower. Newcomen steam engines were larger and much more expensive. The larger size was due to the fact that piston steam engines became very inefficient in small sizes, at least until around 1900 when 2 horsepower piston engines were available. Savery type pumps continued to be produced well into the late 18th century. > > > so it about 200 years of development until it was full steam, quite a time to wrap the brain around different alternative solutions. ## alternatives, stone u may laugh, but the stone is a decent alternative, not every stone but some basalt and diabase, in stationary cases even a good alternative to make a steam engine, with pistons and all that, for engine blocks, for valves. And here is not so well known technology, basalt and diabase casting. Here is some marketing advertisement from the [link](https://www.ethicalstonecompany.co.uk/products/volkanite-cast-basalt/) > > Basalt casting was originally developed in the Czech Republic to be used as a **replacement for iron and steel** which was in short supply after WWII – the crushed natural basalt is heated back to molten lava and then poured into moulds to make components such as pipes and floor tiles, which are incredibly hard wearing and abrasion resistant > > > originally developed by czech's is a marketing, it was started in a good old place where all good stuff comes from revolutions and fashion - by french in 18xx if i'm not mistaken, google brings plenty of links by keywords "basalt casting". in early 19xx some people toyed with the ideas of replacing iron with basalt and diabase casting, but it ended mostly on the primitive side of things pipes where abrasion factor and chemical resistance are important factors, different slabs - this technology still alive. But for early steam the abrasion resistance is a good thing, there are no combustion explosions in a steam engine, there will be no corrosion, almost the same tensile strength with half the mass as cast iron, rocks are abundant enough. So your typical factory steam engine or its marine counterparts can be made out of those casts. there are specific nuances and problems, but no without advantages. Cast iron in most cases, especially simple alloys, most basic stuff is similar in properties with those possible stone castings, except thermal conductivity. And there are limited thermal cycles on a stone block, so u may invent 3 shifts working earlier, or keep it idle under minimal power over nigth. ### pipes Copper was used as an alternative for pipes under pressure - an advanced example of that is a car Doble Model E, some can see it in here as an example [1925 Doble E-20 Steam Car - Jay Leno's Garage](https://www.youtube.com/watch?v=rUg_ukBwsyo) nice piece of engineering, which uses copper pipes as its boiler, and 58bar pressure which is way more than early steam engines can handle. for mobile applications replacing iron in boilers can be a bit challenging, but for stationary not impossible with mortar and stone may do the job, the main problem here is a poor thermal conductivity of stone, which is good for a shell and bad heat exchange, so even if u put stone pipes inside the boiler, as it was done with steam locomotives, it will be less responsible on changing the power until u improve on that, and Doble Model E is a showcase how it is can be done and that it may be as responsible as your typical car. ### shafts and gears it is pity that nobody mentioned composite materials as some of the replacements. But with stone, it is one of the ways to overcome one of its disadvantages namely brittleness of it. Chemistry in times of stem engines was on its rise in 18-19xx, and at the beginning of 19hundreds, there was already a good variety of plastics available. So as making glass fiber. And those were used for gears, bearings (friction bearings) etc. composite materials are not only your typical fiberglass, metal + fiber also a composite material, metal metal etc. it all needs their own development, and coincidently they are all about replacing metals|iron improving its qualities, and compared to our history in the environment of inaccessibility of iron all that development will start early on and it will bring its fruits early, as simple cases are simple and what one needs is mostly incentive, which we got when "iron" become not good enough. *gear boxes* - there are more than two alternatives for making gearboxes - different hydraulic solutions(more than one), different variable speed solutions which can be done out of plywood for machines at 1-2-3kw power, different belt solutions, hydraulic transmissions etc - there are solutions which can avoid problems of lack of strength in gear teeth or brittleness of them by not using them. For lower power solutions plastic gears, composite gears, aluminum gears, etc work fine. # Energy, after steam. what caught my attention in Gary Walker's answer is the oil extraction problem, it begins to be a problem at times when high-density power sources are in demand, and it comes at a time of more advanced technology. So as chemistry vessels and high-pressure vessels for mass chemistry production, which again is a sign of more advanced technology and so as more advanced technological competencies to solve those problems. So as agriculture plows etc will need solutions. As space rockets - there are different solutions to approach the problem of high volume high-stress vessels - that are different composite materials, aluminum alloys. So as with other space technologies to solve corrosion resistance, heat resistance - and iron isn't used that much(exclude engine) - so space technologies is our top-notch benchmark for some cases and it sort of shows to us iron isn't a winner here. however, a transition from steam to that, in which combustion engines played their role, may come in a different way, maybe even somewhat skipping it. The same way as electric-powered cars didn't fly in 1900's, because of the convenience of alternatives of combustion engines, so as Doble Model E died for the same reason. in case of the absence of iron - electric powered solutions are the convenience and Doble Model E fights not internal combustion engines but electric-powered vehicles and probably wins over at some applications. u probably won't see those high powered airplane engines of wwii, sea ships engines as those low rpm monsters will also have certain problems. So there will be a plethora of problems, but it does not differ that much in the complexity of problems we solved to get us where we are today. A characteristical difference maybe that u may work with less powerful or less compact solutions, jump additional hops be more creative, which will take its toll but not impossible. * in time of wwii there were ship hulls made out of cement * helicopters maybe not a thing, but airships may still be a thing (airships can be quite efficient, better than trucks, and a 1.5 times worse than railroads) * precise manufacturing won't suffer that much, but there can be certain limitations on a big size, which is not that critical for making semiconductors as an example. * big big machines monster trucks, excavators - pretty much kiss it goodbye, until u set a firm food at composition material and nanocarbon. * jet engines, fighter jets, etc, probably arrivederci too. * turbines do not necessarily suffer the same fate, but it needs a redesign. * rotary combustion engines may be more popular than as of today * fiber optics and a broadband connection - no problems * electricity generation - doable but less efficient, preferably direct mechanical energy usage where it is possible (in production, as the backbone of tech development it is possible almost everywhere) * springs will have a hard time and they are used a lot, but in some cases, there are alternatives(pneumatics as an example) in others u may need to avoid them by means of design and find other alternatives (chemically tampered [glass](https://www.youtube.com/watch?v=Y46UO2MjPps), [Compliant mechanis](https://en.wikipedia.org/wiki/Compliant_mechanism)) * cutting tools - more synthetic diamonds will do, I think it worth the change, lol * bearings - more friction bearings, hydrodynamic bearings, hydro and aerostatic bearings, ceramic bearings which in many cases just are a better alternative to your typical one. * structure elements more plastic, more aluminum, more composite materials. * connections more glue use and epoxy and adhesives * higher focus on chemistry * firearms will have a problem, particularly powerful and rapid-fire ones. However, there are rifles with composite barrels. * etc where it is a problem in need to solve it will be solved directly or by going around. some technologies which didn't fly in our tech tree can fly in an iron-absent tech tree, some solutions can meet its nerfing, some won't fly. the key technology of today - microelectronics and all the electronics can be achieved and be not affected that much. ## Things that will be harder * resource gathering, large scale mining operations will be harder * deep hard to get oil extraction * high tech wars * getting down to 3% population in the agrocultural sector will be hard ## remarks * if u can improve upon of brittleness of stone and limited heat cooling cycles which is the same problem, then it can be used everywhere where cast iron was and is used. * in absence of an alternative it pointless to refer to economic incentives as we see them today, as we do have options, but they don't - it is done or doesn't. And expenses are defined by widespread technology - the meaning amount of supply, amount of energy put in the refinement of technologies. Ceramic bearings are exotics to us, but for them, it can be a get-go from the very start when they needed them with decades of refinement of technologies and establishing production chains and capacities. * ferromagnetic materials can be a problem for electric engines, so as generators - but it is not one which can't be solved by an excess of wires, so it is not a fundamental one. So as nickel and cobalt will play a more significant role where u have to have them. one does not have to have those metals more, u just use them less and only in places where they bring u the most, power plants as an example. okay, those are my two cents on the topic ]
[Question] [ One of the biggest problems about writing merfolk warfare is related to weapons. You can not slash underwater without expending a lot of energy, stabbing is much easier. Water has more drag than air and makes the sword move slower. That’s why in my merfolk society, swords are very rare. Most merpeople prefer to use tridents, spears or harpoons. But one of my protagonists is an exception. He uses a sword, because his magical powers allow him to do so. He has the ability to increase water temperatures, thereby boiling water and turning it into steam. While using his sword, he uses magic to heat the weapon, turning water around it into steam. The steam condenses when it comes in contact with water again. Could the protagonist use this technique to brandish the sword more quickly through the water? Notice that the sword was not designed to slash enemies. It’s the protagonist’s way of directing his boiling powers. He cannot boil all the water around him, as that would boil everyone around, including himself. However, I suppose a blow from this super hot sword would be enough to hurt his enemies badly. Important information: * The protagonist is resistant to high temperatures, so heating the sword WON’T HURT HIM. His enemies don't have that resistance * He can boil water at a very high speed * The sword is made of an imaginary material that does not melt and is not damaged by consecutive heating and cooling * He has considerable physical strength, so it's okay if you have to make a little effort to move the sword, as long as it doesn't become a major disadvantage Taking all this into account: 1. Would it be possible for this sword to work, and to make rapid movements through water? 2. Would it be worth using that sword, or would it be easier to just use a spear? 3. What material could this sword be made of? [Answer] Don't use magic to heat it up, you will end up having more troubles than you had before you enchanted it. Instead, use magic to give it speed. As you move something inside a fluid, you cause the fluid surrounding the thing to flow. If the thing is streamlined, that can lower the pressure of the fluid. That's important for ship building because below a certain water pressure, it [cavitates](https://en.wikipedia.org/wiki/Cavitation): > > Cavitation is a phenomenon in which rapid changes of pressure in a liquid lead to the formation of small vapor-filled cavities in places where the pressure is relatively low. > > > When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate a shock wave that is strong very close to the bubble, but rapidly weakens as it propagates away from the bubble. > > > This tends to love up propellers and hulls. But if you really go fast enough and the whole object is quite streamlined, it can [supercavitate](https://en.wikipedia.org/wiki/Supercavitation): > > Supercavitation is the use of a cavitation bubble to reduce skin friction drag on a submerged object and enable high speeds. Applications include torpedoes and propellers, but in theory, the technique could be extended to an entire underwater vessel. > > > (...) > > > A supercavitating object is a high-speed submerged object that is designed to initiate a cavitation bubble at its nose. The bubble extends (either naturally or augmented with internally generated gas) past the aft end of the object and prevents contact between the sides of the object and the liquid. This separation substantially reduces the skin friction drag on the supercavitating object. > > > Russians have been experimenting with [supercavitating torpedoes](https://en.wikipedia.org/wiki/VA-111_Shkval) for decades now. The torpedo forms a bubble of vapor around itself, so only the tip of the torpedo actually touches water. The whole thing then literally flies inside the moving bubble at nearly 370 km/h (about 230 mph). --- Anyway, back to your guy. If the sword is just fast enough (> 25 m/s, or 82 ft/s), it will form a bubble around itself which will allow you to apply a very fast cut followed by an implosion that will surely hurt a lot. If your protagonist is able to hold the hilt as the sword moves forward, they can also literally fly underwater just like Thor does on air with Mjölnir, which also adds [Rule of Cool](https://tvtropes.org/pmwiki/pmwiki.php/Main/RuleOfCool) to the whole thing. [Answer] My solution is simple. Stabbing swords and small slashes. **Stabbing swords** Rapiers come to mind when we start talking about stabbing swords. Basically they come in many forms but all of them are thrust centeric, some to the point of having no edge and others to a lesser degree. Anyway rapiers offer excellent hand protection, they also have reach over even cavalry sabers, and are some of the best unarmored fighting weapons as they are fast and agile. Now don't mistake the weapon for less manly sword as rapier have the same mass just distributed in a different manner. They are longer and thinner and made to thrust quickly while keeping the enemy at bay and offering excellent hand protection. Also remember that many rapiers were war swords and those tended to be a bit shorter with a more cutting blade because duh. **Small slashes** In reality big telegraphed moves are not really that much of a thing. In reality a sword fight can be as quick as two heart beats. I highly recommend seeing HEMA (Historical European martial arts) video on YouTube as it would give you an actual idea of how actual fights went. Small controlled moves, a cut and a retreat. Nobody just raises the swords as high as they can like they are using a hammer. That leaves you open to probably more than enough attacks to kill you. So even in reality you just jab the opponent or do a small cut and that's it. So both can be done underwater with little effort, your protagonist is super powerful anyway, and can be very realistic. On the realism aspect let me tell you a well known technique. Halfswording. Basically if you are fighting an armored opponent your chances of doing damage with the conventional sword fighting is minimal. So you grip the sword from the middle and thus turning into a dagger and try to get that little sharp edge into a gap. Sword were also used to be held as a club with the pommel at the top and using the pommel as an improvised warhamer. **Both, and many others, are 100% realistic techniques used in history.** So just say that your MUMA (Merfolk Underwater martial arts) focuses on small cuts and slashes. Here are general sword advantages that you might like and make you incorporate the sword * Every part of a sword is a weapon. The pommel the crossguard and grip are all incorporated into actual fighting manuals of history. A spear is great but swords can be more versatile. * Swords were EDC (every day carry) side arms of the times before pistols. Obvious truth is obvious but even underwater I think trying to carry a spear or pollaxe on your back is troublesome. So while even above water the overall advantage of spears existed. People found it easier to carry a sword. * Paired with how every part of sword is a weapon a sword is a much more dangerous weapon in CQC. You can manipulate the blade better to defend yourself in tight spaces or from an enemy that just closed the distance. In my opinion when you introduce the underwater fighting element this might make swords **more** useful as the enemy can just come at you from an unexpected angle and that leaves you less time to react and fight back. * Armor void swords. So sorry. If you have armor your swords will suffer trying to get through it. That is if it compared to full plate armor or something similar. Basically I think you can keep the sword even without the magic. But as "Renan" so logically suggested just have the magic be like he said if you magic. Other than that just add the bits about ease of carry and overall advantages of swords and that the martial art itself helps and voila. You have swords underwater without magic or with little magic as possible. Personally if I can use magic in the situation even for small stuff I would just bring a box of dagger points, or just nails for maximum cheapness effect, and accelerate my weapon of choice to hit the enemy with enough force to penetrate armor. Rinse and repeat. That would be even cheaper than bullets. Or I'd make little spiked balls that I will shot and have a couple of them run around in the opponents body for several seconds until the desired effect is achieved. Or for maximum serious and grimdark stuff just cut their veins from the inside or explode their heart or brain or rupture their lungs directly. I actually use this magic in a world of mine. Wizards there take like 3 second to kill a dozen . But I digress. [Answer] **It will look awesome! Until it sticks in your opponent and you cant get it loose.** The bubbles of steam will go straight up, as will heated water. None of that stuff will stay in the vicinity of sword or merperson for very long. The sword will appear as a swirling mass of bubbles. If the sword is hot enough to immediately boil all the water it touches, it will be swinging thru steam. Given the rate of water change in the vinicinty of the sword this sword will be consuming tons of energy. If you hit someone with this sort it will burn the bejeezus out of them. The sword does not cool down when it heats other things up so unlike a burning hot thing that cools down with bodily fluid, the sword will stay hot. A bad thing about this is that the hot sword will stick. Imagine cooking a steak on an unseasoned iron pan. The steak is your opponent and the pan is your sword. Your sword will stick fast in or on your opponents flesh. Burning will hurt your opponent but this might be less likely to kill than the same force hit from a regular sword. Burn damage is less rapidly lethal than a deep slice or a stab. Also your opponent will not bleed out - the sword cauterizes the wounds it makes. Your sword getting stuck may be worse for you - if your opponent is physically large or very tough he may be able to deal with the burning sword and come at you regardless. You might have to abandon your stuck sword. Hopefully you got some of those ninja throwing stars in your shirt pocket. [Answer] It is not helpful for moving the sword, But they can use the sword anyway, and it makes a wicked defensive tool. first water is a very good thermal conductor so your merfolk is going to be scalded constantly. If they still have a sword hand after trying this they are lucky. Watch a reenacted sword fight in slow motion and track the movement of blade and hand and see how often they cross each other, with your effect every time this happens the merfolk is putting their hand and arm in scalding water. You say heating the sword won't hurt them how about boiling water. Of course they can use this against the enemy as well, the enemy is not going to approach through a cloud of scalding water. Second, what you are describing is the leidenfrost effect. Which works if the METAL is hot enough to flash boil the water. Boiling the water directly will not have the same effect and will not reduce drag much unless they can boil the water in the entire arc of the swing, Which is a lot of water and something you said they cannot do. but why bother if they are using a sword designed for thrusting (which were common) it will work just fine underwater, just as well as a spear. Honestly if they just need metal for a focus rig up hollow metal tube spear in a spear gun and use is like super heated bullets. make one opeing smaller than the other in the tube and boil the water inside the tube, you can get it to accelerate in the water like a rocket, very fast acceleration to boot. Better yet get a gun, you can boil the water in the tube and get more power than gunpowder, use it to fire spears. Heck get a hollow copper ball with a few holes drilled in it and you have grenades. [Answer] Theres videos of people lifting Olympic barbells underwater. I doubt a sword will be a problem, the slash won't be as fast as if done in air, but fast enough. Just like how an underwater punch still hurts, even if not as fast as out of water. ]
[Question] [ The Humern empire uses [Photonic Railways](https://worldbuilding.stackexchange.com/questions/96104/can-i-overcome-the-bandwidth-limitation-on-my-photonic-railways) to transport its unimaginably vast cargo containers from one solar system to the next. These ships can reach truly staggering velocities (>0.8c even for 'short' journeys) before finally stopping their acceleration phase. Each ship on the railway is a series of huge, very precisely crafted mirrors, and as such any form of impact could be catastrophic. The ships that form the 'train' follow one another along a very finely controlled series of lasers. Each ship reflects the light for their own propulsion back to the base station, and the light for the next ships further along the line. Needless to say the Humerns have some pretty impressive precision mirrors, laser technology and material engineering skills. Even with all their technological prowess interstellar gases and debris can still cause an issue for the photonic railways, and so the Humerns use 'Ploughs'. A Plough is a large blast shield (usually 10x the diameter of the following ships and designed to be thick enough that it will survive the trip) and set of massive gyroscopes, designed to either absorb or deflect interstellar gas and debris away from its more fragile followers. It requires a lot of laser stations at the sending end to speed it up, and often the Ploughs are allowed to 'crash' into elliptic orbits around the target star for capture using more conventional means rather than being slowed by laser stations at the destination (or sometimes they're just flung into the interstellar void). The question is this: How many Ploughs will be required to clear (and maintain) a path through the somewhat inaccurately named 'void'? Will a large fleet when the railway is established be enough to clear the path for generations to come, or will each train require its own Plough to clear the way? [Answer] Given that you'll be cutting what are essentially straight lines across the orbital plane of the galaxy you're going to need to plough the line continuously in realtime at the head of each train and even then you are going to have incidents. The greater the angle the line cuts across the mean orbit of the galactic arms the worse the situation will be when it comes to lateral impactors getting at the train behind the plough, so lines directly outbound from the core to the rim are at greatest danger from lateral debris strikes behind the shield while lines that run retrograde near orbital lines are the safest. Running prograde near orbital lines will be very dangerous; during the acceleration phase debris can "catch up" to the back of the train because it's moving slower than the mean motion of the material around it. In the case of tangential and prograde lines there is also the possibility of late phase occlusions where debris gets between the launch station and the train after the plough has cleared the line and blocks laser light emissions from reaching the train at all. Retrograde lines are safer but not immune to this phenomenon. In short you're looking at a plough at the front of every train, a shield behind some of them that you can shed fairly early in the run, and a steady, small, but significant lose rate in incidents ranging from slight damage to single containers to the cascade demolition of whole trains. Space is huge and very sparsely scattered with matter, the rate of loss will be staggeringly low as a percentage of traffic but it will be there. [Answer] **Give each train its own plow** High-velocity impacts with lightweight projectiles don't follow the intuitive pattern of a bullet drilling through anything in its way, requiring very thick armor to prevent penetration. Rather, the faster the projectile, and the lighter it is, the more the impact resembles a [small explosion](https://www.udri.udayton.edu/AerospaceMechanics/ImpactPhysics/PublishingImages/FlashRadiography.jpg). At relativistic speeds, and with individual atoms of interstellar medium, the result is an explosive burst of radiation that does not penetrate no matter how thin the shield is. Mitigating this radiation and sustaining the ablation rate of constant bombardment are the primary concerns. Thus, the plow does not need to be incredibly thick or enormously massive. On a trip to Alpha Centauri (4.4ly) at up to 0.2c, a spacecraft would appear to suffer [only half a millimeter of ablation](https://arxiv.org/abs/1608.05284) to a quartz shield. The individual particles explode on contact with the shield, blasting out microscopic divots, but not penetrating through to affect the spacecraft behind them. As long as the shield is thick enough to survive ablation over the duration of the journey, it will suffice. At 0.8c, the amount of energy released in each impact will be *considerably* greater than at 0.2c, but the required shielding still isn't excessive. If the rate of ablation scales linearly with the kinetic energy of collision, this implies around a centimeter of ablation for the 4.4 light-year distance. Each train can be given a shield just a few centimeters thick and slightly larger in diameter than the train itself- there's no need for it to be ten times the size of the train, or for it to be the size of a spacecraft in its own right. A simple, disposable shield made of easily-available materials will suffice, can be recycled and reformed into new shields at the destination, and in the context of interstellar travel is so cheap it's hardly worth accounting for. [Answer] # You don't need ploughs. Two parallel beams, going in opposite directions, left on continuously. The cargo vessel has a little bit of maneuvering ability (mirrors), so halfway there, it drifts into the other beam and begins to decelerate. Where it could have a collision with a returning ship at relativistic velocities.... OK. Four beams, two pairs, or maybe two lanes in each of two beams, if the beam was wide enough. A debris object (particle, pebble, nut, bolt, wrench, etc.) that floats around in a beam is accelerated in the direction of travel. The smaller its mass, the higher the acceleration (barring shadows cast by the vessel). The geometry and composition of the side of the debris object receiving the beam would affect velocity components normal to the axis of the beam, so you'd want to make sure that objects wouldn't drift from one beam to the other somehow. So anyway, *the beams plough the road.* You'd maybe want to leave the beams on for awhile when the system is first booted, to clear the space. Debris objects would be entering the destination system at relativistic velocities, so you'd want to point the beams above the plane of the destination system's ecliptic. Even so, given undefined object geometries and such, it seems there would be some spread or divergence from the more collimated beam. Since incoming cargo vessels would have a bit farther to travel, they could perhaps use mirrors or similar to establish an approach vector to an unloading station, and leave the beam earlier. So what happens when an object drifts into a beam? The drifter would be lit up. Forward sensors on the cargo vessel might be able to detect its position (blue-shifted infrared?). If the beam width were large compared to the width of the cargo ship (its *beam,* heh), it might have enough room to establish a minor course correction possibly months ahead. Probably off-topic details: * Civilizations downstream from the cargo vessel's system might become annoyed at the rain of relativistic rocks on their turf, which all seem to come from a very precise point in the sky. * The political relationship of both the source and destination systems would have to be completely harmonious over an indefinite number of decades, even at fine detail. Some dissident group tows something (perhaps a long rod of tungsten) tied to a course-correction unit, into the beam, and they can nuke places in the destination system. How would you police that volume of space? [Answer] Use the laser beam the train rides on to clear the lane just before sending the train. Just send a big burst followed by the train. Anything solid that's moving just in front of a train will probably make things worse as it will disintegrate and create more junk to fly though. ]
[Question] [ A creature has evolved to protect the herd. Its blood contains chemicals that act like pepper spray, burning the eyes and throat of anything around it. However it wants to be able to get a decent coverage on a pack of predators. **So how large an area could the blood be sprayed into?** To clarify I'm picturing a weaker member of the herd being caught - perhaps a younger one - and when the predator's bite severs an artery the blood is released. I suppose, really, the question can be interpreted as "How high a blood pressure is possible?" Another few points: * Gravity: Similar to ours * Animals, same basic structure - hearts pumping blood around and such. [Answer] You're right that blood pressure can be used as a proxy for how far it could potentially be sprayed. Knowing that healthy human blood pressure should peak at around 120mmHg, and bottom out at 80mmHg, it can spurt [around 15 cm vertically and 46cm laterally](http://content.time.com/time/magazine/article/0,9171,748742,00.html). The giraffe has one of the [highest recorded blood pressures](https://bpsfuelforthought.wordpress.com/2012/08/14/why-giraffes-dont-have-brain-damage/) in the animal kingdom at 240/180mmHg due to a host of cool physiological features, so you could loosely double the spurt range from an artery to 30cm vertically and 100cm laterally. However, animals make use of other liquid projectiles: * [Skunks](https://en.wikipedia.org/wiki/Skunk#Anal_scent_glands) can accurately spray secretions from muscled anal glands with a high degree of accuracy as far as 300cm (which can cause irritation and even temporary blindness). * Bombardier beetles rapid-fire [superheated benzoquinone](http://news.mit.edu/2015/how-bombardier-beetles-produce-defensive-spray-0430) [quite accurately](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC22274/) up to [20cm](https://www.sciencedaily.com/releases/2008/04/080401170543.htm). * The [spitting cobra](https://en.wikipedia.org/wiki/Spitting_cobra) can spit venom from its hollow front fangs [up to 150cm](http://blogs.discovermagazine.com/notrocketscience/2010/05/14/how-spitting-cobras-shoot-for-the-eyes/#more-1611) at a victim's eyes. * Southern [giant petrels](https://en.wikipedia.org/wiki/Southern_giant_petrel) can defensively squirt stomach oils up to [100-200 cm](https://blogs.scientificamerican.com/tetrapod-zoology/living-pelagic-life-petrels-part-ii/). Projectile use isn't common in the animal kingdom because of the energetic constraints of making the projectiles, [but certainly has evolved before](https://en.wikipedia.org/wiki/Projectile_use_by_animals). Every mammal can, of course, urinate (larger animals have [higher flow speed](http://www.pnas.org/content/111/33/11932.full.pdf) and, I would assume, greater effective range) to excrete soluble wastes and mark territory. You could invent some interesting defence given that urinating in the face of danger is common to all animals, [including humans](https://biology.stackexchange.com/questions/28578/why-do-we-urinate-more-when-we-are-nervous), but the toxicity of urine is probably dependent on what is consumed in the first place. [Answer] The [Horned Lizard](https://en.wikipedia.org/wiki/Horned_lizard) already does this after a fashion. > > ...are also able to squirt an aimed stream of blood from the corners > of the eyes for a distance of up to 5 feet (1.5 m). > > > This is a single target squirt, not an area effect but nature has already found a solution that you can use as a model. The main thing is that they pressurize the blood in the head to increase the range of the squirt. If you are using simple blood pressure to provide the spray, you are inviting a bleed out situation any time they are injured. It might be better to have blood accumulate in "pressure vessels" or "blood sacks" under the skin that can be closed off when they lose pressure to prevent too much blood loss. It could also have specially designed pores leading to those sacks. If the sacks collect blood waste products, the blood could be mildly toxic or irritating then. You could use the [Cane Toad](https://en.wikipedia.org/wiki/Cane_toad) of Australia as an example. They don't really squirt (it is more like ooze) but there's no reason your critter can't use a similar mechanism under pressure. ]
[Question] [ Despite being awesome marvels and once incredibly important, ever since explosives became a thing, castles have become obsolete. Until now... Imagine two equally advanced civilizations at war. Both factions feel as if castles make great forts in that day of age (futuristic scifi). These castles externally appear as if they are medieval castles but are also armed with higher degrees of defense mechanisms such as force fields and anti-aircraft turrets. They use the castles to hold weaponry and supplies, house troops, and to hold strategic defensive locations. The civilizations don't use exclusively castles but I would say that about 33% of each faction's forts are castles. Why would civilizations with advanced technology (think Star Wars-like technology) even consider using castles as forts? [Answer] Advanced civilizations would find something like a castle useful for the same reasons that civilizations have always found fortresses and castles of various types useful; Because the combination of materials technology and defensive architecture available at that time can overcome the ability of weapons to deal damage to a protected target. If we think about a future civilization with FTL technology (you mentioned "star wars"), we can easily postulate that they would have developed some extraordinary materials technology in order to have an FTL ship that could withstand the stresses and impacts it is likely to see during normal operation. Development of some material strong enough to handle the abuse that FTL travel would probably dish out would radically alter the offensive/defensive paradigm. We could assume that if a ship can be built out of Superstuff, then why not a fortress? We would have to figure that the combination of architecture and materials would be enough to resist/defeat a nuclear strike AND orbital bombardment with something like "god rods". That means we are talking about materials so strong that even if the part of the planet underneath the fortress were vaporized by an asteroid, it would largely be intact. That means the fortress would have most of the characteristics of an FTL ship but probably just lack the drive itself. This could be something that they find useful because of the expense of the drives and the value of whatever other resources are on the planets. We can compare this to the way that castles served as a point from which small armies could "sortie" out against an enemy. Even if the rest of the planet is vulnerable to orbital bombardment, the fortress would be able to cause a lot of damage to attackers while they were within close enough range to attack. Strategically, this might look like the Napoleonic naval war era, where ships were basically floating artillery platforms, but they always had to worry about the superior guns that could be placed on an enemy fort, and forts were built to cover the entrances of strategically important harbors. [Answer] It's not the technology level which makes castles valuable or worthless, it's the differential between the value of being able to hold still, defending a spot of land, and the ability of the attacker to bring offensive weaponry to bear against said emplacement. Castles were very effective in their era because the kings of the day could afford to spend an inordinate amount of labor building structures that were virtually impenetrable to any weapon of the day. The invention of siege weapons changed the balance a bit, but it was still plausible to build a castle so strong that no siege weapon could take it down. This balance was destroyed with the invention of the cannon. No stone structure could withstand the beating that a cannon unleashed on it. The key to this is the sense of time. A king could spend decades building his castle and strengthening it against attackers. Attackers, limited by the mobility of offensive weapons at the time, were unable to keep up. There was also a strong sense of desire to stay in one place. A king did not want to move from his castle, so once it was up, the king could just stay there. So those are the keys to having scifi castles: * A reason for powerful people to want to stay in one place for a long period of time. * The ability to shrug off any siege weaponry which could be brought to bear. The latter is the one which is hardest. Modern combat has found *many* ways to deal with a foe that is willing to hunker down like this. We're so good at destroying things these days, that the most effective combatants are those which are always on the move. That way you can never bring to bear our particularly powerful weapons on them. However, if your technology is shifted such that this is no longer the case, castles could become a thing again. [Answer] Some thoughts: 1. The materials used to construct the buildings could be comparably advanced and resistant to the weapons of the period. 2. Similarly, there could be some inherent trait about their weapons technology that makes a certain natural mineral or material resistant to it, so that material is used in their constructions. 3. There could be symbolic reasons for wanting to have your bases appear certain ways. For instance, perhaps there's a cultural motivation to invoke some historical location or imagery. 4. Depending on the exact nature of their approach to warfare it may actually be advantageous to have a structure like a castle for defense. For example if conflicts largely revolve around ground-based attacks and foot soldiers, it might make a lot of practical sense. Or maybe battles take place entirely in caves. Or perhaps something in the atmosphere hinders their ability for aerial-based combat. Etc. [Answer] Castles, like any fortification, are designed to project power over an area and at the same time resist being taken over. What makes a castle different from a "base" or "bunker" or other fortification is crenelations, arrow slits, moats, double gated archways. These are all things designed to protect counterattackers and make it really hard for **ground-based** troops to enter. You said these castles have force-fields and anti-air defenses (anti-ship, missile, energy beam, god-rod, etc.). Well, once it's clear that air assault will not work, an attacking commander may well switch to ground-assault. It may be that force fields can deflect an energy beam, but maybe they can't stop a physical slow moving object (like a foot-soldier). So, perhaps high-tech weapons have cancelled each other out enough that old-school D-Day style frontal assault is the only choice. And what would be really handy when you've got thousands of armed troops running at you? Crenelations, arrow slits, moats, and gates. In reality, though, I would think a CIWS would take care of just about anyone coming at you. And those things are scary automated. So, to be fair I guess the foot-soldiers would have to have some pretty good armor. Totally doable. [Answer] ## They don't have gunpowder. In an Alternate History Hub [video about gunpowder](https://www.youtube.com/watch?v=ycEZIbQqA8A), or the lack there of, he points out that without gunpowder for bombs and cannons, walls around a city is still a good strategy. You can still have your world have advanced knowledge of chemistry, physics, medicine and mathematics. The can have democracies and vehicles, but without gunpowder to make things go boom, walled cities (basically a large castle) are still a great defensive strategy. [Answer] Logistics considerations. "Castles" are built over strategic-critical resource deposits, which removes the overhead of maintaining resource extraction lines. A sci-fi castle might also be mobile (put a set of massive engines on the bottom so it can relocate). Maybe envision something like the Command Center building in StarCraft, except that it can land on resource nodes and harvest them. Throw in a ring of surface-to-air missile batteries (the "Detector" type, to break enemy stealth) and artillery cannons (probably ripped from decommissioned siege tanks) - that will make it difficult to attack from both ground and air. [Answer] ## Privacy Your faction's troops are well armed and well trained. But when the enemy snaps a photo of their faces, their AI goes to work. Perhaps they posted something "embarrassing" to social media, or stupidly picked their nose in an apartment bedroom *"guaranteed"* to be free of terahertz spying devices. Now their families are being targeted for humiliation. If that doesn't work, their families can always be targeted for *assassination*. The troops, of course, try to be masked and anonymous like Mexican drug police, but when the enemy is willing to use high intensity X-ray beams to sow cancer worries, this can only go so far. The troops tend to stay pinned down in some safe spot, hopefully out of sight, so that they do all these things to the enemy with fewer distractions. A castle, by any other name. [Answer] **For some reason, certain stone materials are the only substance that can penetrate force fields** Say you were able to develop a force field dome, the kind of device that you lay on the ground, and which projects a beam into the air, which then arcs down, producing a near-impenetrable hemispheric energy phenomenon that stops all but the strongest projectile, explosive, and directed energy weapons. A device say, that could even provide a degree of protection against strikes from our contemporary nuclear bombs. This essentially resets you back to the pre-gunpowder era. Attackers can try to chuck stuff at your defences, but you as the defender have the huge advantage. You have two weaknesses, one old, one new. The old weakness is you can't easily resupply yourself, which allows your enemy to besiege you until you have no choice but to surrender. The new weakness is that your force field dome is just as impenetrable from the inside as it is from the outside, so you have no means whatsoever of counterattacking your enemy. So let's handwave that there actually is a way to make little windows in your dome, and that is via some particular quality of the sort of blocks of stone that just so happened to be the kind of material that medieval people built their castles out of. So your fortification will be as follows: * In the centre, the force field generator * Surrounding the generator, all the various buildings and facilities needed to maintain your garrison. * Right at the edge of the force field, stone walls, with protrusions pressing out into the force field, disrupting its effect just enough to create a small window through which a weapon can be pointed out. The outside view of this fortification would be a stone structure, with tiered walls, stepping back in keeping with the invisible arc of the force field dome, dotted with crenel windows near the top of each wall level, through which a futuristic energy weapon peaks out. ]
[Question] [ (First time posting on worldbuilding, be gentle!) For reasons currently unimportant, Earth has been encased in a solid shell which is for all intents and purposes completely invulnerable. The shell cannot be damaged by (for example) meteor strikes or large explosions, and does not allow radiation to pass through it in either direction. By this I mean electromagnetic radiation (including light), and heat. All such radiation is reflected by the inner surface of the shell. The shell appeared in a relatively short time, taking a matter of days or weeks to be placed around the planet. Assume that through some means the shell remains steady about the Earth and there is no chance of it drifting and colliding with the planet. It is positioned high in the atmosphere, somewhere in the exosphere (roughly 600-700km up). If this conflicts with any existing satellites then they can be assumed to have been destroyed. Then my question is: # How would this affect the climate? Specifically: without the sun, would there still be wind and other types of weather? How would the temperature be affected over time? [Answer] Without sunlight, all photosynthesizing plants would die. Then all animals would die a little while later. Most fungi are dependent on the presence of energy-rich (decaying) plant matter, so they may thrive for a long time and then die out after exhausting their food source. It's unlikely that anything other than bacteria can switch their energy source to new chemical sources, leaving only a bunch of bacteria and a few isolated cave-dwelling populations. The composition of the atmosphere will change due to the rotting of all that dead stuff and the bacteria thriving on it. However, due to the lack of sunlight, this will not affect things greatly anymore. Without day and night, winds will mostly cease (no more thermals, only a slight breeze from oceans currents at most). The ice caps will slowly melt, equalizing the temperature across the globe, thus stopping most ocean currents. The planet will become *very* still and mostly covered by water. Over many thousands of years, the remaining bacteria will evolve to a new balance, resembling a ridiculously huge cave. If you're lucky, some of the cave-dwelling animals manage to survive on the surface and spread out a little, but most of the planet is likely too toxic for them, since they evolved in very fragile environments, and even those caves might have been dependent on oxygen-containing water coming from the surface. A few thousands to millions of years more will see rising temperatures as the [heat from the planet's core](https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget) slowly spreads now that the planet is not able to radiate its heat anymore. This is estimated at 43-47 Terawatts over the whole planet, both from radioactive decay inside the planet and primordial heat left over from the planet's formation. It's a tiny amount compared to the energy the Earth used to receive from the Sun, but it builds up over time. In the end, you'll have a scorching hot cave with maybe a few extremophile strains of bacteria left. [Answer] # Cooked Earth (eventually) **In the short term(1 year)**: Darkness descends on the whole earth. No sunlight, no photosynthesis. *All* plants die, which promptly leads to all animal life starving. Or possibly choking to death on all the released CO2 and methane from decomposition of a couple trillion tons of dead plants. The Sphere prevents heat loss by perfectly mirroring, so the Earth quite rapidly (on scale of a few weeks at most) attains a uniform surface temperature. This is very cold for the equator but very very warm for the polar regions. Every single speck of ice on Earth melts. The entire surface stabilizes at about 10 Celcius. his is colder than the current average surface temperature, because all that ice melting will absorb a tremendous amount of energy. But melt it will, as the sky above it "shines" with the mirrored surface heat of the whole Earth. Climate? Expect some interesting floods, including swamped shorelines, due to all the melting ice. There will be no energy input into ocean evaporation and air convection, so the rains will almost immediately stop. Winds will rapidly drop down to very vague breezes only, caused by the slowly equalizing temperatures around them. With no differential hot and cold spots, the weather will essentially just cease to exist. **In the Medium long term(about 100 000 years)**: The Earth then proceeds to cook itself. With no cooling factor on the surface, with the core still at about 5000 Celcius, the whole Earth will eventually attain a uniform temperature. Something like 4500C. **In the really, really long term (several billion years)**: The Earth still contains a lot of radioactive isotopes, that still undergo normal radioactive decay, with the energy release that goes with that. End result: Earth will settle at between 45000 and 50000K, once *all* radioactives have decayed. This will take a while, make sure you have taken out the extended warranty on the Universe, with optional "outside interference" clauses. Can't have the sun going red giant interfere with our little cooking experiment, can we? ]
[Question] [ I have a race of people who have silver blood. Thing is, I'm really trying to keep it as realistic as possible despite this being a fantasy world. The blood has raw magic energy in it as well, but doesn't mix so were you to collect blood, there would be a silver/bright red (the color of raw magic here). So far, and this is all working and will change with more information. Some things I know so far that may or may not be affected by the compound/color upon oxidation choice: when they blush they *do* get pink-red tinge because of the raw energy. If one of these people, for some reason doesn't have the energy in the blood, they pale instead. I have never specified if the blood changes color when they bleed or between artery/vein blood, but perhaps upon hitting open air it might turn black. Bruises are a ruddy gray to a charcoal black. My only caveat is that they have to remain looking enough like "humans'-- the skin color is a narrow range of different levels of caucasian (ranging from kind of pale to kind of olive-y tan depending on activity level. They usually remain very light). They are also of a different blood than other races there as they are a sort of "invasive" species in that they were created long after the other races were a thing. Those with raw energy in the blood will be "pinker" than those who do not-- If there is none, they will be very, VERY pale. Any help would be so appreciated. I've tried looking for ages, to no avail! I want to make this work! My best guess right -now- is that perhaps the blood is colorless, and it's the -plasma- that's silver? [Answer] Depends on what you really mean by silver. Silver, the element, (Ag) can be bright and shiny like chrome. Silver oxidizes, like iron does. However, iron turns red when it oxidizes. That's why our blood is red. [Silver turns black when it oxidixes](https://www.google.com/search?q=silver+oxide). If you want to use actual silver, and have your race breathe oxygen, then the blood isn't going to appear silver in color. Also silver is solid at room temperature. Mercury (also known as quicksilver) is liquid at room temperature and very shiny. Problem is, when it oxidizes it turns [orange, red, or yellow](https://www.google.com/search?q=mercury+oxide) depending on how fine the crystals are. The color white and the color silver have historically meant the same thing if that helps. If you can be flexible with your definition of the appearance of silver there is [titanium oxide](https://www.google.com/search?q=titanium+oxide). It can be white or dull grey in color. In my mind, this is your best bet. Of course, nothing says your race needs to breathe oxygen. But carrying oxygen is the primary function of the only kind of blood I know. Your race could be doing something different with it. [Answer] Having blood that is literally a metallic silver color while also transporting nutrients and oxygen is going to be difficult, if not impossible. The accepted answer to [this question](https://worldbuilding.stackexchange.com/questions/28276/other-blood-colors?rq=1) provides a list of different oxygen-carrying proteins and their colors when oxygenated and deoxygenated. The closest are probably hemocyanin, which is colorless in the veins, and coboglobin, which is colorless in the arteries. Other proteins not listed here might give a grayish or milky-white color; but I don't think there's any for an aqueous solution to give you a metallic sheen. However, who's to say it has to be an aqueous solution? You're already talking about raw magic energy here, so these creatures' blood could literally be liquid mercury and it wouldn't make any less sense from a scientific perspective. Or liquid gallium, if you're worried about them poisoning anyone they bleed on, although their home environment would have to be a bit warmer than Earth for that to be feasible. Gallium melts at 29.76 °C, between room temperature and human body temperature. Alternatively, their blood might be a normal color when in their circulatory system, but turn silver upon exposure to air. Much as exposure to air triggers human platelets to release sticky proteins and start coagulating, it might trigger your creatures' blood to produce a film of some material that looks like silver foil. I'm not sure what that material would be or how it would work, although a strange type of atmosphere\* could do it. Or it could just be magic. \*If your story happens to take place on a world with an atmosphere rich in hydrogen (such as [this one](https://worldbuilding.stackexchange.com/questions/75115/plausibility-mechanisms-for-biogenic-silica-on-a-terrestrial-planet-with-a-reduc), or any old gas giant), it could be silver ions in the blood being reduced by the hydrogen in the atmosphere and precipitating out as silver metal. However, a creature from such a planet would have great difficulty surviving for very long on Earth without a space suit. [Answer] Rather than focusing on having the blood be possessing of metals, perhaps the cells comprising the majority of the blood contain a refractive meta-material whose structure reflects light in such a manner that it *looks* silvery. Such things are actually quite common in nature and are responsible for iridescence among other phenomena. As for why they would possess such a feature? Maybe the unusual structure of their blood cells are what enable them to "drag" the magical fluid around the body... [Answer] Perhaps the blood contains very fine particles or colloidal silver. These could be encapsulated in some form of membrane which would prevent oxidation and would help ease the transportation of them in the blood stream. These metallic particles might be needed for reinforcement of the skeletal structure to provide extra strength. Haemoglobin could also be present giving the blood its red component colour as well as providing oxygen and removing carbon dioxide. Damage to tissue might well rupture some of the particle membranes causing oxidation. This could be one of the bodies defence mechanisms. Once some silver started oxidizing it could create an inflammatory response rupturing further particle membranes until any wound had scabbed over with high Silver oxide content. Damage to tissue without breaking the skin might cause different oxidative processes such as the formation of Silver Phosphate which is yellow or other [organosilver](https://en.wikipedia.org/wiki/Organosilver_chemistry) compounds might form to give almost any colour depending on the exact chemical composition. Silver might also be used in the body as a catalyst either in its elemental form or more likely incorporated into Silver containing enzymes. It also has some antibiotic properties. Silver would have to be reasonably abundant in the environment to make this credible. An alternative would be for the blood to contain a colloid suspension of particles of a size suitable to create diffraction effects producing a range of colours for example: [![gold](https://i.stack.imgur.com/LTmxG.jpg)](https://i.stack.imgur.com/LTmxG.jpg) gold particle but a wide range of materials can form colloidal suspensions. [Answer] **I think it could actually just be silver** Human hemoglobin is composed of iron which acts as an oxygen carrier. This is why when blood is oxidized it turns red (rust). Silver is also a metal which easily oxidizes. I believe it could be used in replacement of iron in the blood. Because it has a smaller ionic charge than iron you would need more. Depending on the quantity their blood could actually look shiny silver when unoxidized and tarnish when oxidized. Would be interesting having people hunt them for their blood. **Nickel could also be used:** Just as iron and silver it can be oxidized. When unoxidized it appears shiny kind of like silver when oxidized it just dulls slightly. ]
[Question] [ So in the sci.fi world I am currently building, I am trying for a fairly technical approach to space combat. Movement is cumbersome and you're strafing more so than performing maneuvers that aren't really possible in a vacuum. Larger ships are much slower since you're fully reliant on thrust to turn and you probably won't want to have a main engine facing in every direction (though that is an interesting thought to play with...) Space combat is a fairly long-distance affair (compared to modern ground/naval combat anyway), get too close to the target you're blasting and you risk collision with debris at critical velocities, etc. It is also important to note that I have "shields", in the form of unstable Alcubierre warp bubbles which, rather than producing a coherent bubble, just creates a field of unstable/oscillating spacetime around your ship whose tidal forces can, at least to a certain extent, bend lasers and tear apart projectiles. It's a bit random though so of course ships carry varying degrees of armor as an extra layer of defense. **In such a setting, I am wondering what kind of weaponry would be the most sensible to carry on your spacecraft?** The primary types of weapons I am looking at are * Conventional ballistic weapons * EM-accelerated weapons (rail/coilguns) * Self-propelled weapons * Mines * EMR weapons (lasers) * Particle weapons * Drones --- ### Conventional ballistic weapons Probably not the most convenient in space. May still be used for handheld weapons but the velocities and distances at which space combat happen make these a bit tricky to use. Gunpowder-based weapons probably won't fire well in a vacuum anyway, as far as I see it ### EM-accelerated weapons Electromagnetically-accelerated weapons are probably fairly convenient. You fire them electrically, the payload need not that large and can be a simple ball of metal (the kinetic impact itself is fairly heft), and, for coilguns especially, there's not a lot of wear and tear. You can, as far as I understand it, achieve really impressive speeds, especially if you build a two kilometer long weapon. I imagine capital ships are, *very* simply put, just massive coilguns with ships attached to them and your main objective in space combat is to maneuver your ship/main gun into position safely and have it blast down stuff. Not sure if the speeds at which a coilgun fire can penetrate a warp shield well. Another idea is to have them fire plasma shells, going for burning rather than punching a hole in. ### Self propelled weapons By which I mean rockets and the like. Like conventional kinetic weaponry, probably a bit difficult to use efficiently at long distances, easy to shoot down etc. Can possibly attach small warp drives to them if warp drive miniaturization has come far enough (and production is cheap enough) that you can slap a drive to a torpedo and send it on its merry way; the spacetime distortion of a warp bubble should do significant damage to enemy hulls (and warp torpedoes may very well be able to penetrate warp shields with one of their own?). The question of whether the warp drive is pinpoint enough is also a problem. ### Mines Space is vast and it's pretty hard to observe everything, especially if it doesn't actually give off heat signatures or other such radiation. It's quite possible that mines can be potent; jettison them off in the direction of an enemy craft's flight path (or litter the area around space stations/common atmospheric entry locations with them) and mayhem ensures. It may be a good way to deter people chasing you. ## Lasers/EMR weapons Accurate, instant (unless you are fighting at a distance measurable in light seconds) and quite possibly lethal to spacecraft, though it might not pack the heaviest punch; maybe sufficient thermal armor might stop a laser from burning through a hull. Lasers are probably also really good at point defense; they can easily blast down incoming missiles, can be turret mounted to offer a wide firing arc to deal with pesky maneuverable craft and drones, and so on. ### Particle weapons Imagine a particle accelerator, only you direct the particles at your enemies. It should in theory work really well and there's a lot of kinetic energy carried. ### Drones Not a different "weapon" per se, but small unmanned drones equipped with any of the other weapons can fly in swarms to try and overwhelm enemy crafts' defenses with a quantity over quality approach, they can carry signal interference to disrupt communications, and may be more viable users of plasma weaponry to burn through hulls. --- I'm mostly just assuming how things will work and there's a lot of conjecture, so I'm very interested in hearing exactly what kinds of weapons are good, and how they would be good, in a space warfare setting. How exactly do lasers impact their targets and are particle weapons better at this? Do particle weapons have to deal with cooldown like lasers? Are there significant drawbacks to coilguns (apart from being dodgeable at long distances)? And, relevant for my setting specifically, will a projectile traveling at fast enough speeds survive a strong tidal force (warp shields) better (since it'd technically be affected by it for a shorter period of time)? Are there other kinds of space-based weapons I have not considered? [Answer] As far as I see it, much depends on the way your Alcubierre Drive works. As I cannot comment as of yet, I will attempt to answer this in two directions. ## Conventional Guns They work perfectly fine in space, the propellant already contains the oxidant as do all explosives. But you're right that their muzzle velocity doesn't compare to the more exotic mass driver concepts. However, they could be used to attack drones at very close range with saturation fire. However, there are some concepts to increase the velocity of the projectiles, for examply by using a light gas cannon. Since we talk about the large distances, this wouldn't be feasible either. ## Railguns / Coilguns Solid projectiles can be accelerated to very high speeds while remaining absolutely accurate and not losing any power over the distance. Solid projectiles could also have the benefit that when they are being fragmented by the alcubierre shield, they still could inflict damage with high-energy fragments. Railguns also have the benefit that you could design self-propelled weapons that can be launched via railgun, thus decreasing the time to accelerate. Another benefit would be that vessels with a small industrial facility could make projectiles without the need to go to port, as they could melt down asteroids for material for the projectiles. On the flight-time until hit: Over the possible distances enabled by an alcubierre drive, even light will have a delay until it hits, and launching a sufficiently large swarm of missiles will prove to be difficult to completely avoid, depending on the attack- and defensive strategies employed. A note on coilguns: while the abrasion of the rails may be a problem, coil guns, as far as I can see, are quite inefficient in the amount of energy required, require very complex control structures to enable the magnets to work as intended, and you're required to use ferromagnetic projectiles, whereas in railguns you could use anything that conducts electricity, or use a conductive sled like a sabot and use that to propell a non-magnetic/conductive projectile. ## Self-Propelled Weapons / Drones / Mines As you wrote that combat should occur over fairly large distances, I dont see why classic combat drones make sense: they would be on their way for a very long time and represent a good target for defensive fusion bombs, MASERs and even railguns before the drones are even within their effective combat range. Secondly, the drones need to decellerate before they can reengage after passing the target once, depending on the distance that may be rather impractical. Therefore, I would not make a difference between drones and self-propelled weapons but instead use them as one and the same. Equip them with fusion warheads and make them kamekaze. You could use them both offensively and defensively. However, they need to be shielded enough for fully autonomous control methods to work with nuclear explosions going off in a couple of hundred kilometers distance. The winning side would then be the one with a combination of more drones and better attack programs/evasion patterns. Those drones could then also be used as mobile mines. But keep in mind that mines in general only make sense if the target needs to reach a specific location. ## EM Weaponry EM Weaponry like lasers seem to me to be only useful as a short range defensive weapon to deteriorate incoming projectiles and drones, preventing them to impact or coming close enough for their warhead to make a difference. Why is this? Well, even in space, the diameter of a laser beam will widen considerably, thus decreasing the amount of energy per cm² impacting any object at distance, as the [inverse square law](https://en.wikipedia.org/wiki/Inverse-square_law) tells us. This may vary depending on the size and technology for generating and focusing the beam. A kinetic projectile does not have this drawback. Depending on the technology base, I would suggest MASERS or X-Ray Lasers for this purpose. Edit: MASER is an acronym for Microwave amplification through stimulated emission of radiation, meaning a LASER in the microwave wavelength region. You can use other wavelength, though I would not go as far as using a GRASER as base, as gamma rays tend to penentrate the amplification mechanism... ## Particle Cannons I think you'd need even more resources to operate them than railguns or masers. To achieve a saturation area dense enough, they might be large and require their particle "fuel". While they may be very powerful, they will probably suffer from the inverse square law. [Answer] If you have Alcubierre drives, then the drive itself can be weaponised. It is expected that the forward field will accumulate photons and release them ahead of the ship when the drive field collapses, in the form of very high energy photons. By triggering a burst of Alcubierre warp in the direction of the enemy and pumping photons into the forward drive field, on dropping warp, the photons, now carrying a lot of energy, will continue on toward the enemy. See <http://ut-images.s3.amazonaws.com/wp-content/uploads/2012/02/MatterOfMatter-revised-final.pdf> [Answer] Given the scenario as described, the primary mode of attack would be to find a way to collapse the unstable bubble of space time being used as a shield. In inertial space, the primary weapon will still probably be a Ravening Beam of Death (RBoD) mounting a kilometre long electron beam accelerator to drive a freaking huge FEL that can pump out beams at X-ray frequencies. The RBoD can deliver enough energy to vaporize steel, ceramic and carbon fibre components in milliseconds at distances of one light second, almost the distance from the Earth to the Moon. Indeed the beam will be dangerous to a distance of a light minute, and can deliver a lethal dose of radiation at a light hour! (RBoDs are described in the Atomic Rockets website under conventional weapons <http://www.projectrho.com/public_html/rocket/spacegunconvent.php>, while the discussion of RBoDs vs SCoDs comes from the "Rocketpunk Manifesto" blog under space warfare <http://www.rocketpunk-manifesto.com>.) As a practical matter, slow moving ships will be effectively stationary at a distance of one light second from a laser weapon of this power, and the energy being dumped into the shield bubble could be enough to destabilize it. Once it collapses, the ship is open to being sliced apart in detail, unless collapsing the shields actually causes catastrophic damage to the ship itself. [![RBoD](https://i.stack.imgur.com/mgoAe.jpg)](https://i.stack.imgur.com/mgoAe.jpg) *A conceptual diagram of the RBoD* The kinetic energy counterpart to the RBoD is the "Soda Can of Death" (SCoD), a device the size of a soda can accelerated in great numbers against ships carrying the RBoD. Tens of thousands of SCoD's will simply overwhelm the ability of a RBoD to track and eliminate every one, and the overwhelming mass of incoming SCoD's will strike and destroy the RBoD. The kinetic energy of incoming SCoD's could also tend to overwhelm the shield, causing a collapse and damage to the underlying ship. To cover the distance in a semi plausible timeframe, either ICBM sized missile busses need to be used, or massive rail or coilgun platforms like the SDI era conceptual project "Have Sting" (Diagram from Atomic Rockets, via Scott Lowther <http://up-ship.com/blog/>) [![Have Sting](https://i.stack.imgur.com/DH8d3.jpg)](https://i.stack.imgur.com/DH8d3.jpg) *Railgun concept* Although you have not specified this, if there is a version of the Alcubierre drive, then you might be able to do long range attacks using drones mounting the Alcubierre drive to chase down targets at superluminal velocities, then attacking as a conventional missile or bringing a portable version of the RBoD with it (bomb pumped X ray lasers come to mind). The Alcubierre drive itself could be used offensively to manipulate the space-time around the shield, negating the effects, or amplifying effects in a runaway feedback loop and tearing the drive mechanism apart. The massive changes in space-time around the ship could also physically damage or tear the ship apart, depending on what sorts of distortions and gradients could be arranged next to the ship. [Answer] # Sandcasters! These special missiles are full of little lead pellets. They're actually intended for intercepting missiles, but the then-pilot "Sandy" Gray realized that there's nothing stopping you from launching them at the enemy. A one gram projectile moving at .999c carries a ton of energy; about 500 kilotons. You can probably pack a million pellets in a missile. With a million little chances to breach the shields, one is bound to get through. As a bonus, it's basically impossible to dodge. *DISCLAIMER: I'm not a physicist and this might be wrong.* $E\_K = \left( \frac{1}{ \sqrt{1 - v^2/c^2 }}-1\right) \times m \times c^2$ $E\_K = \left( \frac{1}{ \sqrt{1 - 0.999c^2/c^2 }}-1\right) \times 1g \times c^2$ $E\_K = 1.887×10^{15}J$ [Wolfram](http://www.wolframalpha.com/input/?i=1g%20at%20.999c%20relativistic%20kinetic%20energy) // [NUKEMAP](https://nuclearsecrecy.com/nukemap/?&kt=500&lat=40.72422&lng=-73.99611&airburst=0&hob_ft=0&psi=20,5,1&zm=11) Godspeed, Sandy. [Answer] Provided they could get past your fancy shields, **lazzorz!** Remember, in space, there is no matter to conduct heat away from you. Lasers would be a really good way to add energy to an object and heat it rapidly. If the ship is unable to deal with the excess heat, they'll have to surrender, lest they risk their crewmen being literally **boiled alive**. Also, kinetic kill vehicles. Essentially, what Holdo did in the new star wars movie. Light-speed projectiles would be really hard to detect, and almost impossible to avoid, not to mention exceedingly deadly. Also, if you're being really careful about physics, I don't think your space navy would use conventional projectiles. Every action has an equal and opposite reaction. If your ship attempts to perform a broadside barrage, your ship is going to propel itself away from its target, and will have to waste fuel correcting its trajectory, so weapons that will propel themselves without affecting the vessel (missiles that fire once detached from the vessel, lasers, etc.) Recoil-less weapons, in essence. I'm no science-man, though. I may be wrong about what I said above. [Answer] If you plan to use the FTL drive in combat, you will need weapons with an FTL effect. Otherwise the target will outrun the weapon fire. That excludes everything on your list except for FTL missiles or drones. If the FTL drive is used only for interstellar flights and not in combat, small ships have no advantage over little ones. Sublight speed means **acceleration** and **delta-V**, and delta-V depends on the fuel or reaction mass percentage. [Answer] I had a similar problem when I wrote my first Sci-Fi book. I deduced that explosive projectiles that were encased in plasma were the most effective. My early weapon concept was a pump action gun, with turrets (the revolver cylinder kind of turret) mounted on the top, containing explosive charges. When fired, a field of plasma is emitted from these charges, before violently exploding after letting out the rest of the plasma at once. These prove to be very effective at penetrating through armour, and then obliterating whatever was left of it inside. Any ships floating around in space aren't going to be able to out maneuver your shots, and variations of this weapon can be created with the same basic principle of plasmatic charges to better fit your needs. [Answer] One thing you may want to take into account is litter. If you're using physical, non-guided/propelled projectiles, if you miss, then that projectile is Going Somewhere. There is in fact a whole (hilarious) rant about it in one of the Mass Effect games as to why we do not "eyeball it" since once you fire that projectile, it will keep going until it hits something, a thousand, a million years ahead if necessary. For a conscientious species, you may wish to stick to Directed Energy weapons or particle weapons. "Sir Isaac Newton is officially the deadliest sonfoabitch in space." [Answer] There are lot of ideas, so I will just add some. **Burrowers** Droids that try to reach the other ship and pierce its hull, or disable important systems or releasing a EMP inside the ship or near the commanding centre. Creating as little debris as possible, while disabling the ships. **Plasma breathers** Shooting a cloud of plasma that can disperse after a certain distance. In close proximity it could do great damage to the ship, while it creates no debris and the shots that missed will become more harmless with distance, eventually returning to their standart gas form after it radiated enough heat. (Nebulas caused by large battles?) **Tractor beams and magnetic manipulators** You could slow down the large ships and throw around with the big ones, you could also collect surrounding debris and use it offensively. **Graviton bombs** Huge magnets released into the battle... space, that can attract ships making them crash into each other or to force a large ship to move. And the bigger the ship the greater the effect should be. Or strong gravity generators that, when close to a long ship, force its' hull to bend and break. **Warp torpedoes** A torpedo carrying a faulty or damaged warp core, when it reaches its target it activates, doing whatever a unsuccessful warp travel does. (ripping the ship to pieces, trapping it somewhere, or just deplete its energy, so the ship would stay in one piece, or just take it out of battle for a while) [Answer] MatterBeam suggested Light-coupled particle beams. <http://toughsf.blogspot.com/2019/02/cold-laser-coupled-particle-beams.html#more> It is essentially a particle beam with an additional guiding laser to fight the dispersion of the particles, giving you more range than you can possibly use with light-lag. The result is comparable to a Xray-FEL Any kind of particle weapon will have penetration that depends on the atoms used as well as the target, with heavy atoms generally getting stopped quicker. A proton beam may kill electronics and crew through armor if it is not thick enough, unlike a laser. Heavy atom beams can get to higher energies in the same accelerator, giving you more energy on target if you want to try melting it to slag instead. A note on plasma shells: Any kind of plasma weapon is likely to disperse really, really quickly. Kinetic slugs, nukes, lasers, particle beams can all *turn* their their target into plasma, but it is generated in-situ. Transporting plasma across free space would need some form of confinement. [Answer] What about a nuclear option? Just take a powerful enough A- or H-bomb and place a large metal rod (made from wolfram or something) close to it. Move the whole construction close to enemy, with a missile or something. Then detonate the bomb. It provokes upward energy level changes in the electrons in the metal rod (before it evaporates away). These changes are released as gamma quants when the electrons plop downwards the energy level. You get a pretty coherent stream of gamma radiation in the direction of the longer rod axis. This is a nuclear-powered **gamma laser**. Pretty cool, huh? --- And speaking of long wolfram rods. If you want to attack a planet from space, just plop down such rods (or ones made from depleted uranium, for maximal fire-starting damage) from the orbit. Gravity is a bitch, inertia and kinetic energy even more so. A purely **kinetic weapon**, no explosives needed. [Answer] To boil down your weapons further, you have three main types: * **Kinetic**: Conventional projectiles, Railguns, etc * **Beam**: Your lasers (light-speed) and particle cannons (near light-speed) * **Self-Guiding**: Missiles, Drones, Fighters and the like Everyone will know where everyone else is, as there is [no realistic stealth in space](https://worldbuilding.stackexchange.com/questions/23313), thus most ship battles will occur at light-second distances, if not further. You always want to be as far away from the person trying to kill you as you can after all. The main effect of this is the delay in information. If your sensors pick up a ship ten light-seconds away, the information your sensors give you is already ten-seconds old. Assuming you're firing light-speed weapons (beams), it'll take another ten seconds to hit, thus you need to aim at where you think the enemy will be in twenty seconds from the location you can currently see him. For Kinetics, this problem is even worse, as your projectiles will not be moving at light speed, and will thus take more than ten seconds to reach your target. Self-Guiding weapons however, do not have this problem. They can be launched many times further away without having to worry about predicted target location, as they will be constantly adjusting to ensure they reach the target. No, you would thus think that Kinetics are useless compared to Beams and Self-Guiding weapons, however Self-Guiding weapons are typically much more expensive. Just compare any modern missile or UAV to a standard field gun. They may be of similar size, but that gun has much more ammo, and much cheaper. Also, Self-Guided weapons would likely move slower and be larger targets than kinetic munitions, meaning they more more easily be countered by point defence. Whether the size of an object matters for an Alcubierre shield is for you to decide. Beams are straight-line weapons, whilst Kinetics are affected by gravity(1). This means that you wouldn't be able to hit a target on the other side of the planet you're orbiting with a Beam weapon, but you could with a Kinetic weapon. A hit from a kinetic weapon would likely be much more severe than a hit from a beam weapon. Any solid object flying at high velocity would have ridiculous amounts of momentum, and would be able to punch straight through ships. Meanwhile, a Beam weapon would be coming up against the standard radiation shielding a ship would be obliged to carry to protect its crew from solar flares and other natural, space-based radiation. Finally, Beam weapons will suffer from attenuation, meaning they do less damage at long distance. A Kinetic round will do the same damage regardless of distance, assuming it hits at all. Thus firing solutions will generally involve volleys of self-guided projectiles, with shotgun-blast volleys of Beam weapons at long range and Kinetics at short range. Quickly addressing **Mines**. Classic stationary mines would be worthless. They would easily be avoided by anyone going slow enough, and if they're going too fast, then you could just as easily use anything bigger than a [fleck of paint](https://www.washingtonpost.com/news/speaking-of-science/wp/2016/05/12/a-bit-of-debris-chipped-the-international-space-station-thats-just-one-piece-of-a-much-bigger-problem/?utm_term=.347da438fa8a), which chipped the windscreen of the ISS. In reality the only thing resembling mines would be drones set to hang out in an area of space, and then automatically target anything that comes into range. These would fit into the Self-Guided category above. (1): Not actually true, but for our purposes the effect gravity has on light-speed and near-light speed projectiles is negligible. [Answer] I like the idea of using some of the more insidious techniques. Perhaps a railgun/coilgun could be used to fire nanobots. The nanobots manage to get past the ship's defenses and still carry enough energy to penetrate the hull. Now the nanobots start converting the hull into more nanobots. The issue is that nanobots must be externally controlled, so they each carry a few qbits that enable quantum communication with a main control. Now these nanobots can be configured into additional weapons to fully disengage or destroy the ship. There is, of course, using the ships to batter each other. Perhaps smaller Alcubierre drive powered drones could launch themselves into the space-time bubble of the ship. This will generate space-time ripples which could have immense energy seeded into them (perhaps by warping large distances or travelling through stars). This would effectively tear apart the ship, even as the drones themselves will likely be destroyed. Since these are warp drives, they make the most effective long distance weapons. Another version of the seeding idea fires a ion beam or antimatter beam and drives into it using warp. The result is that energy concentrates at the edge of the warp bubble and is released at the point that the ship stops travelling. This is, of course, very risky depending on the weapon but if the energy concentrates at the edge of the warp bubble then when it is released it will be similar in energy to gamma ray bursts (or worse). Since the direction of travel and the seeding of the field means that the direction of imbalance is outward rather than in towards the ship, it is possible that the firing ship will survive this. Another idea is to tractor beam and warp close to something dangerous like a black-hole. Your unwilling passenger is dropped into the gravitational pull, while you emerge just within the escape zone. You zoom away while watching the frozen image of their doom emerging, smudged across the horizon of the blackhole, viewable for the foreseeable future due to the odd spacetime effects of blackholes. Once we get to technology of this level, of course, any warfare is very dangerous. It makes it very likely that mature civilizations will shun warfare and seek alliances. This makes it far more likely that the civilization that you are fighting is an emerging power, and not careful enough of the dangerous weapons it possesses. [Answer] You can use a concept like lasers; they can be more targeted to damage shields. Because the lasers definitely have the velocity to pierce the shields of an enemy ship. I also think that we can use particle accelerators (if they can be shrunk down and with the use of efficient energy sources mounted on the ship) can fire a high velocity stream of electrons, which may not damage the ship but will bypass the hull altogether and target the DNA of the soldiers, enabling the side to capture the ship and salvage resources, rather than destroying them altogether. I am a space geek..so I am a bit technical:) ]
[Question] [ Suppose we have a planetary system in orbit around a [Class O](http://en.wikipedia.org/wiki/Stellar_classification#Class_O) [hypergiant](http://en.wikipedia.org/wiki/Hypergiant) star of 225 solar masses (larger than all but R136a1, the largest star we currently know of), 32,000 times as bright as our sun, and with an effective temperature of 40,000 K, and that the star exists for far longer than our understanding of stellar physics says it should because of [historical plot point]. * What would be the habitable zone (capable of supporting liquid water) for a planet with an atmosphere and size similar to Earth, but several times more dense? * Would there need to be any special qualities of the planet itself to protect it and any life on it from the sun's energy output? * Is there a theoretical limit to the number of moons a planet can support and, if so, how many moons can this planet support? * Assuming one day on the planet is roughly 30 hours, what would be an estimate range for the number of days there are in one complete revolution around the sun? Please note: Magic has a strong presence in this setting, but I'm looking for plausible, mundane solutions to the problems presented. Edit: From HDE's answer, my number of 32,000 times the luminosity of the Sun may be inadequate to the task. HDE suggested 320,000 as a replacement. Feel free to adjust the luminosity if you feel a different value fits better, but please defend your choice. [Answer] Some of your numbers seem to be way off: * **Mass:** The theoretical limit on the size of stars is around $200~M\_\odot$. As a star grows larger and larger, it gets brighter and brighter. Eventually it reaches a point where the outer layers of the star are blown off by the radiation pressure. You may be able to get to $300~M\_\odot$, but not to $3000~M\_\odot$. * **Luminosity:** Your luminosity is a huge underestimate. Most supermassive stars will, for the reasons mentioned above, be close to the [Eddington limit](http://en.wikipedia.org/wiki/Eddington_luminosity): the maximum possible luminosity for a star of a given mass. It is equal to: $$ L\_\text{edd} \approx 34\,000\left(\frac M{M\_\odot}\right)L\_\odot $$ A $225~M\_\odot$ star would probably be between $1\,000\,000-10\,000\,000~L\_\odot$, several hundred times more than you predict, and a $3000~M\_\odot$ star would probably be billions of times brighter than the Sun, exceeding the limit, for the brief period before it collapsed/exploded. I'll continue, assuming a $225~M\_\odot$ star with a luminosity of $3\,200\,000~L\_\odot$. (Based off the luminosity of [this star](http://en.wikipedia.org/wiki/R136a1), the most massive known currently). The radiation budget of a planet does not depend on its size, since the amount of solar energy received and amount of thermal energy radiated are both proportional to surface area. However, the surface temperature will depend on the atmosphere's thickness and composition, especially the presence of greenhouse gasses. I will assume an atmosphere similar to Earth's in thickness. (Note however that, due to the increased gravity, the density and pressure of the atmosphere will necessarily be increased, but it will not reach as far into space.) Making the above assumptions, we therefore want to place our planet so that the solar constant (incoming solar energy per unit area) is the same as for Earth. Due to the [inverse-square law](http://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Extrasolar_extrapolation), this disance will scale exactly with the square root of luminosity. The distance is therefore $\sqrt{5\,000\,000}\approx 2200$ times Earth's orbital radius, or $2200~\text{AU}$. Serban noted that there would be increased stellar wind. Indeed, R136a1 is estimated to be losing mass at a rate of $50~M\_\odot/\text{My}$. This only amounts to about $300~\text{kg}/\text{s}$ of wind impacting your (Earth-size) planet, almost 1000 times the wind at Earth. I would suggest giving your super-dense planet a super-strong magnetic field to protect itself (this also nets you super-intense [magical?] aurorae). Now from [Kepler's laws](http://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion#Third_law) we know that the period of an orbit is: $$ T = 2\pi\sqrt{\frac{a^3}\mu} $$ We can again simply compare to the Earth-Sun system by ratios. $\mu$ is 225 times greater, and $a$ is 2200 times greater. Therefore the period is about $\sqrt{2200^3/225}\approx 7000$ times greater: in other words, this planet would have a year as long as agriculture is old on Earth. Assuming a 30 hour day, that's about two million days per year. A planet's moons are inside its [Hill sphere](http://en.wikipedia.org/wiki/Hill_sphere), or sphere of gravitational influence (an exception is our own moon, which is incredibly huge compared to other planets' moons). The size of the Hill sphere is: $$ r\approx a\left(\frac{m}{3M}\right)^\frac 1 3 $$ For your planet, the distance would be about 0.01 times the orbital radius $a$. But remember that $a=1000~\text{AU}$: that gives the Hill sphere a radius of $22~\text{AU}$, twice the size of Saturn's orbit. So you can probably pack in as many moons as you want. Note however that the moons are likely to be small, like Saturn and Jupiter's moons, which are thousands of times smaller than their parent planet. A large moon would sweep up all the smaller bodies as they formed, resulting in an Earth-Moon-like system. [Answer] Oh, good, a planet habitability question. I love these. > > What would be the habitable zone (capable of supporting liquid water) for a planet with an atmosphere and size similar to Earth, but several times more dense? > > > I recently wrote [an answer](https://worldbuilding.stackexchange.com/questions/9559/what-would-a-binary-black-hole-look-like-from-the-surface-of-a-planet-orbiting-t/9618#9618) on Worldbuilding referencing [an answer](https://earthscience.stackexchange.com/questions/3120/what-are-the-criteria-that-make-a-planet-inhabitable/3190#3190) I wrote on Earth Science containing formulas from [Planetary Biology](http://www.planetarybiology.com/calculating_habitable_zone.html). In it, I give the formulas for the inner and outer radii of the habitable zone of a star: $$r\_i = \sqrt{\frac{L\_{\text{star}}}{1.1}}$$ $$r\_o = \sqrt{\frac{L\_{\text{star}}}{0.53}}$$ Plugging in the luminosity (320,000 times [that of the Sun](https://en.wikipedia.org/wiki/Solar_luminosity)$^1$), I get $$r\_i=539.36 \text{ AU}$$ $$r\_o=1302.31 \text{ AU}$$ To put this in perspective, the [Oort Cloud](https://en.wikipedia.org/wiki/Oort_cloud) only extends to 50,000 AU - still substantially larger than this, and very, very far when compared to the orbits of the planets in the Solar System. > > Would there need to be any special qualities of the planet itself to protect it and any life on it from the sun's energy output? > > > Not really, if it's positioned correctly. But the [effective temperature](https://en.wikipedia.org/wiki/Effective_temperature) might be different. This calculation is relative to the Sun and Earth. The formula is $$T=\left( \frac{L(1-a)}{16 \pi \sigma D^2} \right)^{\frac{1}{4}}$$ I get$^{1,2}$ an effective temperature 0.000028 times that of the planet if it was orbiting the Sun at 1 AU, which seems pretty low. But the habitable zone calculation is done relative to the [stellar flux](https://en.wikipedia.org/wiki/Radiant_flux) of the star. Still, this is weird. To fix it, the planet needs to have a much lower albedo ($a$), though that still wouldn't make much of a difference, it seems. I'll have to revisit this and see if I made any errors. > > Is there a theoretical limit to the number of moons a planet can support and, if so, how many moons can this planet support? > > > Well, no, in theory. The distance from the star *shouldn't* affect the stability of a given system of moons around a planet, but something that has to be taken into account is the fact that the [circumstellar disk](https://en.wikipedia.org/wiki/Circumstellar_disk) around the star would have had a much lower density this far out, and so there would have been less material nearby for moons to form and be captured. The formula for density is $$\rho(r)=Ce^{-\frac{(r-r\_{peak})^2}{2 \sigma ^2}}$$ where $\rho$ is density, $r$ is the distance from the center, $C$ is a constant, $\sigma$ is one standard deviation, and $r\_{peak}$ is the radius at which the density is at a maximum. So the density this far out is going to be *much* less than the density at 1 AU. However, there might be a different $r\_{\text{peak}}$ around a class O star. > > Assuming one day on the planet is roughly 30 hours, what would be an estimate range for the number of days there are in one complete revolution around the sun? > > > The rate of rotation shouldn't affect the rate of revolution. As 2012rcampion wrote in his/her excellent answer, we can use [Kepler's laws](http://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion#Third_law) for this. Using the figure of a radius of 920.835, I get a period of 1871.81 Earth years. Have fun with the seasons! Multiple planets could absolutely exist within the habitable zone, given that this one is so big. The only thing that might make their existence less likely would be the fact that it's unusual for planets to form that far out from the star, and it's unlikely that even one could form that far out, although it *could* move outwards from a position closer in. --- $^1$ As 2012rcampion pointed out, 32,000 $L\_{\odot}$ is *waaaaay* too low for a star like this. I'll multiply that figure by 10, because [VY Canis Majoris](http://en.wikipedia.org/wiki/VY_Canis_Majoris) has a luminosity of 270,000 $L\_{\odot}$, and it seems you want to go a bit brighter. $^2$ From here on out, I'll use an orbital radius of 920.835 AU, the mean of the two radii calculated at the start. ]
[Question] [ What kind of a scenario would have to occur in order for human beings to seek survival on the sea floor? It could be man made or natural, ice age or heat apocalypse, sudden disaster or gradual collapse, I just want to know how it could get to that point. I'm talking about either living on the bottom of the ocean in built structures, or underneath it in tunnel systems. [Answer] Radiation, either from the sun growing unstable or from some persistent cosmic event, sleeting down from space. A few meters of sea water will block most of the radiation that would effectively sterilize the land. People could build shelters on land but what would be the point? There's not biosphere left on land. Also, without the land biosphere buffering heat and carbon, the climate would be massively erratic, likely with super storms and possibly rapid cycling mini-ice ages at random places. Everywhere would turn into a desert devoid of life but with the same rainfall. With no life to hold soil, huge swaths of land would simply turn to mobile mud. The ocean would also have the advantage of easy, protected mobility. Trade and migration would be safe and easy. All hell can break loose on the surface but a hundred meters down, everything is smooth. Likely, it would start with the radiation anomaly growing over a period of years, enough to make preparations. Nuclear submarines and static basis are built. Major land resources are moved to sea accessible locations, perhaps islands. Preferably the initial refugees would be away form major continents or at least rivers because a lot of crap is going to wash into the seas. Only a few millions at most out of billions could be moved under the sea initially, but there would be survivors on land for years or decades. They could be rescued as capacity under the ocean increased. Lots of room for story conflict there. The pioneers under the sea, likely the "best and brightest" having a life of mission but also material privilege while at the same time the survivors on land growing haggard, desperate and bitter. [Answer] The first thing that comes to mind is an incredibly large volcanic eruption. And I mean a *huge* eruption. Something never before seen on Earth. One of the largest (if not *the* largest) eruptions we know to have happened was that of the [Toba supervolcano](https://en.wikipedia.org/wiki/Toba_catastrophe_theory). It released a staggering 2,800 cubic kilometers of ash, and covered most of South Asia with a layer of ash 15 centimeters thick. It may have killed off a substantial portion of the human population. But we would need something even bigger to make all of Earth's land uninhabitable, possibly a series of large volcanic eruptions caused by some massive tectonic instability. The [Ring of Fire](https://en.wikipedia.org/wiki/Pacific_Ring_of_Fire) could be a significant contributor, although most of the ash could fall in the ocean. Essentially, you would need all of the world's volcanoes spewing out all of their magma - and then some. Unlikely - probably impossible - but it could still drive humans off of land. What about that [ice age](https://en.wikipedia.org/wiki/Ice_age) you mentioned? Well, once again, we'd need to cover all of Earth's land. Is that possible? Not by the effects of recent ice ages, but the [snowball Earth](https://en.wikipedia.org/wiki/Snowball_Earth) hypothesis has some potential. It states that, at least 60 million years ago, Earth underwent some cooling, which formed more ice, which then led to more cooling and more ice. Wikipedia suggests (just as I was thinking!) that a supervolcano could have lowered Earth's temperature just enough to start this cataclysmic cooling. There are some other obvious causes (which it also lists - perturbations in Earth's orbit, asteroid impact and an impact winter, reduction in greenhouse gases, etc.) which are a little more mundane, but equally possible. So if you can trigger any of those, you can trigger a snowball Earth. The one man-made cause I can think of is a large nuclear war. Radiation would have to be distributed just right so that while Earth's land would become overly toxic, its oceans would be fine. Controlled bombs could produce this desired effect, but there would have to be a lot of them - many more than we have today - and they would have to be detonated in very specific spots, so as to make sure the oceans were unharmed. This would, admittedly, be nearly impossible. [Answer] Broadly speaking you need three things: (1) something that makes it infeasible to keep living on land (most people won't move unless pushed), (2) the inability to evacuate from the planet, and (3) enough time to build and move into those underwater habitats. For (1), other answers have proposed [radiation](https://worldbuilding.stackexchange.com/a/2814/28) and [volcanic eruptions](https://worldbuilding.stackexchange.com/a/2809/28). These work if they can be forecast far-enough in advance to allow for (3); surprise global terrorist attacks with nukes probably wouldn't allow people to move into the oceans, but a decades-long climate change or major volcanos gradually "heating up" over decades could. To radiation and volcanoes you could add massive air pollution; the logical response might be to move underground, but some will see that as just kicking the problem down the road a bit and move into the water sooner. (You're going to need oxygen and nutrients, and I suspect they're easier to get from the ocean *in the long term*.) You also need to keep people on earth; this could be accomplished several ways: * We don't have off-world colonies yet. * We do, but we can't get most people there. (Possible story point: if we can get *some* there, who gets to go?) * We have capacity but it's much more expensive to ship people to Mars/Luna/wherever than to go into the sea (so maybe the "haves" go to space and the meek inherit the earth, so to speak). Finally, you need to be able to move people into the sea. You'll need a history of sizable underwater structures (labs, observatories, etc) already, so you're not just figuring out how to build underwater when a global war is heating up. In other words, people will build settlements under water if they already have a foundation of knowledge and engineering to build on; otherwise they will probably dig underground instead, even knowing that that has problems of its own, because we know more about digging. (And if this is set on near-future Earth, we have the established meme of underground bunkers already.) ]
[Question] [ Given: * An ahistorically powerful and advanced Aztec civilisation, anno late 1400s. * A set of circumstances much like the ones that led Columbus west: one mad Aztec convinced the world was rather small and he could reach their trading partners (the Chinese) by sailing eastwards. He sets sail from Haiti, the latest Aztec tributary. The season is undetermined. He has no knowledge of what he'll find on the other side, other than vague records of mythical place called Hindustan. **Where will he land?** Ship facts: * It's built for mainly the Gulf of Mexico, Caribbean sea and coastal waters from Georgia to Venezuela, but large enough to carry lots of tribute - which they now fill with supplies for the journey instead. Think a slightly smaller, Mesoamerican version of Zheng He's famous treasure ship. * There's at least one person aboard who's acquainted with oceanic travel (a Chinese defector - who in this reality regularly crossed the Pacific). The crew at large makes up for their lack of expertise in spirit though. * They do not have a clue what's on the other side of the Atlantic; their goal is to reach China. They do not know any currents that only reveal themselves far past the shores. They are going to have to discover all those things on the way east. Sea facts: Both the [prevailing winds](https://upload.wikimedia.org/wikipedia/commons/1/18/Map_prevailing_winds_on_earth.png) and the [ocean currents (gyres)](https://upload.wikimedia.org/wikipedia/commons/8/8a/Oceanic_gyres.png) suggest a somewhat northerly course to be "ideal"; going parallel to the North American coast for a bit and ending up in Europe. But if you look at [Columbus' travels](https://upload.wikimedia.org/wikipedia/commons/3/38/Viajes_de_colon_en.svg), and specifically the return trips, only on his first journey does he curve northward significantly before heading east, and it looks like he was specifically aiming for the Azores that time. So it is definitely not against the laws of physics to sail a straight eastbound path, which would have our brave Aztec land in Cape Verde or Mauritania. So I wonder if there's an argument to be made that given a sailor with a suitable vessel but little knowledge of the deep ocean (just like Columbus) and no known destination to aim for, that a spot on the Atlantic coast from Senegal to Portugal is most likely to be hit? Or are those prevailing winds/currents so strong and noticeable that any reasonable sailor encountering them for the first time would be compelled to adopt a more northerly course, and end up somewhere between Tanger and Scotland? Or is it all so dependent on the season and weather conditions of the time that any destination between those northern and southern extremes is at least plausible? **Update** So I did some more research and I made a map. [![map](https://i.stack.imgur.com/8fuzK.png)](https://i.stack.imgur.com/8fuzK.png) Fat arrows are winds, thinner arrows are ocean streams (of which the equatorial counter-current is only active in the late summer and autumn, apparently). The lines are all the west-east Atlantic crossings I could find the routes and dates for; just Columbus' four journeys. Don't really know where else to look. It's... not that helpful in the end. Columbus crossed the Atlantic in basically every season, and he only followed the currents or winds twice. Safe to say that I'm starting to lean towards any landing site for my Nahuatls to be plausible. If Columbus could take those routes in spite of wind and currents, couldn't my expedition do the same? [Answer] **They would sail straight east and end up on the coast of Africa between Cape Verde and the Canary Islands.** They do not know the winds, the currents, or the geography on the other side. And more importantly, **most** importantly for your question, they know the do not know. They have no specific goal they can aim for. With the navigation available to them this means they can only sail along the coast, north or south to reach a latitude, or east or west along the latitude. Sailing east along the latitude of their origin is the only one of these options that is useful for the initial crossing towards the old world. You'll note that when Columbus went to Americas he first sailed to the Canary Island the westernmost Spanish holding and then sailed straight west along the latitude. On his return trip he went first north then north-east until he reached the latitude of his destination then straight east. Later trips when he was more confident on the distances and had specific goals in the new world the routes become more precise and less angular because he, and your Aztecs, would have fair ability to estimate the distances sailed. You cannot do this on the first trip over so it is not really relevant to the question but it is useful to note that on his first return trip Columbus was already confident he can sail north-east part of the way and that on his second return he already hits Spanish territory instead of Portugal. And felt confident to cross to west south of his initial trip to more or less continue his exploration where it ended on the first trip. (And knew which direction to go when he found islands.) **If you want them to sail straight to Europe.** Have the trade from China come via Japan and let your Aztecs know its latitude but nothing else about the geography. They would then start by sailing north along the coast to that latitude, then sail straight east. They'd probably end up somewhere in Iberia or France in this scenario. And obviously knowing or guessing the latitude of part of China or Korea on that same latitude is just as good and Japan is just an example. I have no idea what port the Chinese would use. [Answer] The north-northeastern route would probably be the easiest, especially if we're assuming the ship's navigators are roughly as skilled as those on the Santa Maria, et al. This would take the ship, ultimately, to either the Iberian peninsula, or the British Isles, depending on whether the ship ended up following the Canary or Norwegian current, respectively. However, this also puts the ship at the mercy of North Atlantic storms, which, given the Aztec's unfamiliarity with such weather, might be a serious problem for the mariners (this is assuming the Aztecs haven't expanded further north than, say, the Carolinas, which seems unlikely given that Haiti is their newest tributary). Depending on the time of year they set sail, it's a roll of the dice whether they land at all. However, there is a safer, and potentially more lucrative option (though the mariners wouldn't know it when they set out), it just requires a little more navigational acumen and seamanship. Polynesians sailors developed a method of sailing in which they would actually sail *against* the prevailing winds and currents, which meant that if they became lost, they could just grab the prevailing winds and sail back where they'd come from, almost like a kind of navigational save point. If your Aztecs developed this technique (maybe they got as far south as Peru, either conquering or trading with the Incas, and learned the technique from Polynesian sailors there), then they could sail "backwards" along the Atlantic North Equatorial Current, and end up in west Africa. Now, circa 1492, this brings them to the west African shores right around the time that the Songhai Empire is reaching its height. This could introduce your Aztecs to the pan-Islamic trade network, which would, in this writer's opinion, be of far more economic and cultural value to them than introduction to European Christendom circa 1492. [Answer] First of all Columbus knew where he is aiming for. Or at least he knew how the sky should look like there. All he needed was to close the sky map of stars. So that's why the first travel TO was in a rather straight line. They had to keep some sort of regularity while charting. So they used Sun as a reference point. During their way back and other ones they have a rather good idea of what they need to look for in the sky to get back in both directions and that they have enouch "anchor" points to get to place where they want to land. The thing is that distance from China to Americas is much greater than from South America (especially from Rio Grande Do norte) to Europe or Africa. A seasoned (or just knowledgeable) sailor should know about equatorial countercurrent. And they could try to find exactly the same thing on the other side of America. Landing in african congo Basin Area. They would also prepare for a much longer voyage then it would really be needed. Again, because the distance on Pacific is much greter than on Atlantic. Also remeber that Columbus knew where he wanted to land in China/India. You have two set points, you have refrence (sun) and you have, let's say assumed knolwedge of 75% of sky above you. You know the earth is round. So you make the route the way you want. [Answer] Until the Atlantic currents were understood (well after regular trading voyages were set up between Europe and the Americas), Captains would just try to set a course to their destination and then use the winds as they could to get there. Eventually it was noticed that voyages going to America across the northern Atlantic would take considerably longer than those on a more southern course. So courses that are going against the currents are not impossible, but they will make the voyage *much* longer. [Answer] If we are talking wind-driven ships I would most definitely recommend a somewhat north-heavy route leading to somewhere between Ireland and northern Portugal. It is technically possible to go east directly from Haiti, but I don't think it reasonable to oppose both wind and water currents for no real reason, any sane sailor would understand that following those would bring you forward much faster. ]
[Question] [ I have found myself approximately 2000 years in the past, I didn't bring anything with me. But since I am here, I want to conquer the world with my knowledge from the future. Or as much as is possible within my lifetime. Conquering the world means: ruling an empire which stretches across various countries and plenty of statues in my honour. I realise it takes a while to get anywhere at this period; so the empire may peak in size long after I am gone. But as long as they do it in my name / my family's name; it still counts. I have popped up in a location where my conquering of the world is most likely to happen from (Rome perhaps?). I didn't choose this location, I am just fortunate. I studied the local language for a bonus module in school and I'm a quick learner: so I actually can speak with the local people. I didn't plan in advance for all this, but I excelled in school in all areas. I have approximately University undergraduate knowledge of all all subjects. I don't know how to make time machines. I just happened to fall into one. From what I understand, my conquering of the world would require two key steps: * How could I find myself in charge of a military force? * How could I enhance my military force to beat the others of the ancient world? [Answer] You are Augustus Caesar Augustus was not the flesh-and-blood heir to Julius. He was born Gaius Octavius, a grand-nephew of Gaius (Caesar) Julius who would become president of the Republic, but right now is just an over-the-hill statesman who was thrown out of the priesthood job his family had landed him over charges of his wife's sexual misconduct, chilling in Spain, racking up a mind boggling amount of debt and wondering how he will ever amount to anything. Gaius Octavius' father would die when he was young and some unspoken family drama would result in Gaius being taken from his mother and raised by Julia, Gaius' grandmother and Gaius Julius' sister from age 6 to 10, at which point Julia died and his mother and step-father resumed custody. Despite working in the Temple his grandfather Gaius Julius had built before the sexual misconduct allegations, there's not much making it clear if Gaius Julius, traveling as often as he was at this age, knew his grand- nephew at all. Gaius Octavius sought out his grand-uncle, who had since found a way to dodge his debts by using the army he had bought with the money to invade the capital. Julius was currently in Africa fighting to hold together his new position when Gaius Octavius supposedly boarded a boat to join him. Along the way, the story goes, Gaius Octavius was shipwrecked and crossed enemy lines with a small group of comrades to reach the city where Gaius Julius was staying. The story is very reminiscent of an experience being kidnapped by pirates that Gaius Julius had himself at roughly Gaius Octavius' young age. Trading on the story, similar first names, and family connection the lad impressed Caesar, who sent Gaius Octavius to school in Albania to be trained as a soldier. Unknown to Octavius, but known to your time traveller, Gaius Julius had been so impressed, he adopted Gaius Octavius and named his grand- nephew heir to his wealth in his will. Two years later Gaius Julius Caesar would be stabbed to death by friends and associates while in the Senate in Rome. Gaius Julius (formerly Octavius) receives the news while in school and does something remarkable for anyone, but even more so for a 19 year old: still penniless, because he had not yet collected his inheritance, he steals the entire treasury that had been earmarked for an upcoming war in the middle east, uses the money to personally recruit Gaius Julius Caesars soldiers (who considered themselves working for Gaius Julius personally and not the government) and marches on Rome surrounded by his new army (and now in charge of the largest military force in the world at the time). The person who would become Augustus Caesar showed incredible prescience in his decisions then. Mark Antony, one of Gaius Julius Caesar's generals who had been present in Rome during the assassination, refused to release Augustus' inheritance. Nevertheless, by allowing other members of the political class to think they could use the young boy as a powerful tool, the boy was able to manipulate savvy experienced politicians into allowing the new young Gaius Julius to use his army to run Mark Antony out of town. A year later, Cicero helped induct the plebian commoner (which he was) into the Senatorial class, made him a Senator, and legitimized his private army. Then, the politicians tried to sucker the new Gaius Julius into turning over control of his private military to the government. The new Gaius Julius refused, an incredibly bold act that could easily have turned to civil war - but your time traveller would know the Senate cowed. Augustus continued to make extremely shrewd choices for the rest of his life, only serving as president of the Republic for a very short time, but keeping a newly invented legal title that gave him even more legal authority than the president. Despite this extra authority, he only used it once. He invested heavily his grand- uncle's military and financial wealth, winning many friends, but never ceding control. [Answer] I think you cannot do any better than a normal well educated inhabitant of those times. You have two main challenges to overcome: 1. no matter where you go, you will be a foreigner with no bounds to that nations. The only example coming into my mind of a nation allowing foreigners to ruling position is the late Roman Empire, when it was close to its collapse. I am sure that is not your goal. Foreigners in ancient times had way less rights than proper citizens. And a foreigner gaining power and influence will immediately attract the attention of some sword toward the internal of their body. 2. Once you start changing the world line, your knowledge of history becomes useless. Let's say you save Kennedy in Dallas or Julius Cesar: from that day on, you don't know what will happen. While the first one can be mitigated by you ruling from behind the scenes, i.e. acting as a trusted counselor, the second one will make your attempt vain, sooner or later. Unless you plan on switching side at the right moment, so that you don't change the course of history. But if you don't want to change the course of history you cannot afford changing any event at all. [Answer] There is no direct path to world domination. Success will be defined by traveler's skill at playing "Game of Thrones". The starting point is very tough. Time traveler has no money, no connections and only a basic language skill. There is no chance he can impersonate a native citizen. But vast knowledge (hopefully backed up by hands-on skills) should find him employment at some artisan's shop. In there, he can proceed with making inventions that can be in high demand at the time - steel, concrete, spyglass, dyes, or just dazzling toys which can impress rich aristocrats. The second step will be either opening his own shop or becoming a trusted advisor to an important person. Either way, time traveler will have more money and resources at his command, and can build more advanced inventions like crude gunpowder weapons. At the same time, he should continue building trinkets to expand his influence among the ruling elites. Third step should be moving into the ruling elites themselves. He can either get some position of power (like Petyr Baelish had become the [Master of Coin](http://gameofthrones.wikia.com/wiki/Master_of_Coin)) or become king's own trusted advisor, effectively outranking many traditional aristocrats. There, time traveler should thread very carefully, building alliances and trying not to offend anyone. By this time, his manufacturing operations should run with very little supervision, providing a very important money supply. Fourth step would be seizing the power. It can be done directly, or indirectly, by joining a coup and eliminating his co-conspirators later. Unfortunately, modern knowledge can be of very little help here (maybe poisoning technique?), time traveler would have to rely on his own instincts to prevail in this operation. Fifth step would be, naturally, consolidating the power. All challengers must be defeated and imprisoned, or better yet, executed. Army should stand behind the new leader. Aristocracy should see their benefits in the new order. Any potential power imbalances (like extreme power wielded by Roman [Praetorian Guard](https://en.wikipedia.org/wiki/Praetorian_Guard)) must be rectified. This is where good knowledge of history and familiarity with nonexistent yet works like Machiavelli's "[The Prince](https://en.wikipedia.org/wiki/The_Prince)" should help. Sixth step is proceeding with world conquest. At this point, the army should be already superior to anything than its opponents have. Again, good knowledge of history (how great conquests had succeeded, or failed) should help here. Seventh step - make the growing empire stable. Make new countries accept your religion, or join some other, more egalitarian religion that has a better outlook on a global scale. Make lawmakers write a constitution that would provide a legitimate basis for the empire and establish a sensible balance between different classes and provinces. Produce a heir and make sure that no one among your lieutenants could be even remotely interested in a coup. Eighth step - retire and enjoy your growing empire either from a capital, or a countryside palace. [Answer] Here's my plan: * You **somehow** manage to get close enough in time & space to warn Julius Caesar of his planned assasination * This means you need to be **somehow** pretty well versed in ancient roman history - the big stuff as well as the everyday stuff and *speak* latin * Saving Caesar lands you a place as a trusted advisor * You further help your protector with some inventions - given that the romans where quite good at engineering, this is actually hard, some ideas: + crossbows (if the romans can make steel bows) + gunpowder + compass + modern math - calculus could help with formalizing the extensive engineering knowledge ancient romans obviously had * this means you **somehow** know enough about all of these to actually improve upon the ancient roman knowledge. I think it's a safe bet that the roman experts in bridge building, sword smithing, fighting, surgery where pretty good within the constraints their time put upon them. If you want to really improve things, you need to understand those contraints and widen them. * If you want an empire, you won't be able to keep any monopoly on knowledge. The popint of an empire is having people to do things for you, so you need to teach the modern skills you bring along. At the end of the day, you will be kept as an advisor/pet as long as you're useful, and discarded when you are seen as a threat. To get so far, you need an inplausibly eclectic skill list. It's likely a safe bet, that in any ancient society an individual counts nothing if not backed by a family or similar. You, dear time traveller are all alone. [Answer] Assuming you do something like @James-McLellan suggested and assumed the identity of Octavius, now you can start introducing things that will make a significant advantage to your civilization (and altering history). At this point you might want to take a hint from the alt-history/SF Belisarius Series by Drake and Flint, which is all about Giving Radio to the Romans. * Stirrups. This will make an enormous difference in cavalry action, not only giving horse archers a more stable platform but allowing for truly heavy cavalry, allowing proper lancers. * Gunpowder. The Romans will take to gunpowder like fish to water, for civil engineering if nothing else, but could adapt to warfare, especially siege warfare, easily. Because bombs can be flung by... * ...the mangonel and counterweight trebuchet. The mangonel was used in China about this time but won't be introduced to Europe until the 6th century. This gets it out sooner. The counterweight trebuchet didn't appear until the 12th century, but the engineering required wasn't beyond what the Romans of Augustus's time could do by any means. Both allow superior artillery fire compared to the ballista, onager, and torsion catapult, so you don't even need cannons. * The Bessemer Process. It's fairly simple to describe, and not technologically that difficult to do, especially if you start small. Steel in industrial quantities is going to make a huge difference, both in civil engineering and in military technology. * Electricity and steam. *Sooooo* many things you can do with electricity and steam. You want to wean the Romans of slavery, so you don't necessarily go for labour saving right away, but again, civil engineering and military purposes. * Arabic numbering. Some more advanced math. Start inspiring people to think along the lines of the scientific process so they make their own discoveries. There are others, but that gives you a good start to conquer the world. [Answer] When you were studying, did you paid any attention to how to bet people to a pulp with a club? Because without that you will be very fast sold as a slave. Your best bet would be to remember where all the goodies are. Gold, iron, copper. How to make better/faster methods of transportation. Maybe better food for your animals. From then you can became wealthy merchant, buy yourself a military title or strike a deal with some general and lend him your military tricks and money for a campaign. And after that you kill him, take his place, destroy anyone who oppose you and proclaim yourself a ruler of Rome. Or You go to Germania Magma, kill some warlord with a crossbow, teach tribes how to make more crossbows, make better steel armour, invade Rome. [Answer] Start a religion. Worked for some other dude two thousand years ago........ Seriously, basic first aid would save lives and look like miracles. Historical knowledge looks like divine insight. You have whole parables that are old in the modern world but haven't been written yet. Use your knowledge to pass divine foresight to the rulers and support the ones you know will win to become the state religion. [Answer] TLDR: With chemistry and basic physics you can introduce gunpowder and ballistics, form alliances, claim the world. Long: You would probably have the best luck with this in central Asia due to the abundance of resources, but with modern knowledge you could manufacture relatively simply black powder rifles like the [Whitworth Rifle](https://en.wikipedia.org/wiki/Whitworth_rifle) and simple [cannon](https://en.wikipedia.org/wiki/Field_artillery_in_the_American_Civil_War), with that and an introduction of basic modern medicines and farming practices you could rapidly create and maintain a healthy, well fed, armed army, probably around the late 1800’s level of armament until you improve manufacturing techniques. [Answer] I think about this a lot :) modern civilization is not about anything other than vast numbers of people. People mine ore.. others refine it.. others cast it to ingots.. others melt it.. others forge it... Etc. Almost all of your knowledge would either be useless or heretical. Worse you would lack the basic skills to survive.. my plan would be to draw the attention of academics with maths and geographical knowledge.. then eventually work in royal court. Perhaps get the trust and attention of the king.. then using knowledge.. help the king to conquer new Territories. But forging an empire in an age without fast travel is a job that would take more than your 35 year iron age lifespan. I would concentrate on how very difficult it would be to use any of your knowledge in the iron age. How would you communicate for starters. [Answer] If I'm getting it right, Rome was just a possibility. If that's the case then most of these answers are so darn boring I can't believe it. Who wants to read a story about someone who doppelgangered Augustus and just tweaked stuff a bit in Roman history? This is supposed to be great so let's start from New Jersey or Madagascar or Mexico or a remote monastery in Korea. I'm thinking India or Persia makes the most sense, geographically, if we are taking of the Whole World, but sorta boring unless we get lots of elephants doing something fantastic. Medicine, food supply, fast travel and communications are the usual keys. Advanced weapons are great but without the other things taking **and holding** the world would be tedious to impossible. Introduce penicillin and telescopes and dried/canned food and as close to modern ship building as you can. Heck, throw in railroads and you're unstoppable. Add Alexander's intermarriage scheme (with local chieftains' families and military officers to increase stability in your wake. At about that time the Han Dynasty was doing well, developing the Silk Road, and if not for the Han–Xiongnu War eating resources they may have done more. Quite civilized and science oriented your 21st Century thought might serve you best there. [![Han Dynasty](https://i.stack.imgur.com/CkktQ.jpg)](https://i.stack.imgur.com/CkktQ.jpg) The lime green line represents border of Xiongnu incursions. It doesn't seem like leadership was too hard to get if you were able to make a great weapon and show some intelligence. Ideally making peace between them or forming alliance against a Western power would offer enormous potential. Hans could go through India and Xiongnu straight west into what is Russia today, meet up on the other side. India was unified under Mauryan Empire, so work out trade and send ships for troops (use financial trickery to take over since it was a great building time in India) and on through Persia to the Mediterranean. Oh, remember not to leave eunuchs behind in China, they're always starting trouble. After you've taken Europe and North Africa send half the armies into Southern Africa and the rest to Miami. Let's assume you've been collecting the greatest ship builders along the way. Now you have massive armies busy and largely dependent on your control of the seas. Get the armies farming and cooperating with natives and use Alexander's intermarriage scheme. Any unruly warriors left can be sent to Australia (that's what it's for, isn't it?). All along you can be giving them signs to look for, your knowledge of history and geography giving you the aura of Prophet King (say you have visions or something). This way by the time the southern armies get to Egypt and find the pyramids you spoke of they'll be flabbergasted and renewed in faith for you. The northern troops, tell them about leprechauns or meet them on the coast of Ireland with maps of the world best you remember it. ]
[Question] [ *AKA what do underground civs do with their poop?* Vast underground networks of caverns, tunnels and caves are a staple adventurers' playground in many classic tabletop RPGs. To make for entertaining games, these are populated with random monsters, eldrich beings and whole cities of creatures like dwarves, mindflayers, drow and other, more exotic, creatures. The cities and towns of the underground are often surprisingly populous and numerous (again to make for a better story I suspect). That's a lot of potential poop to deal with right there. Modern engineers might struggle in this environment, but D&D and other tabletop RPGs often assume that cities are pre-industrial. It goes without saying that without adequate sanitation: disease will spread, precious cave real estate will clog up, and dangerous predators and scavengers will be attracted to the stink. **Question: What is the most effective way for a pre-industrial city of approx 10 000 underground dwellers to manage their waste?** Assume the additional environmental conditions: * Access to the surface world is often difficult or dangerous. * Light sources are often weak: luminescent fungi, eldrich glow, almost certainly no sunlight. * Travel through the dark and winding paths is also dangerous. * Magic is insufficient for the clean-up task. * Water is limited to underground rivers and lakes (replenished by rain from the sunlit world). + Dumping waste in water is possible, but if it doesn't wash into your own water supply it will almost certainly head into your neighbors' - which leads to strained relations. + Additionally, there is no rain underground, so waste stays where it's left or spread. [Answer] Most likely the waste would be used right away in growing food. Mushrooms grow well in climate controlled environments on manure, which an underground city would have. Once one has grown mushrooms, the left over waste is still valuable in terms of [fertilizer.](https://en.wikipedia.org/wiki/Spent_mushroom_compost) An underground city would still need more food than what could be gotten from growing [mushrooms](http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2482/2), being low in calories, fats, and lacking essential amino acids and vitamins, so the fertilizer could either be traded to the surface, as [biosolids](https://en.wikipedia.org/wiki/Biosolids) or used for [year round production](http://www.chelseagreen.com/blogs/history-of-winter-gardening-the-17th-century-french-garden-system/) of whatever plants can be grown in the underground. The problem with the underground being light levels rather than temperature (as the temperature would be nearly constant). With sufficient light it would be possible to grow tropical fruits year round in a non-tropical environment using the heat from composting waste. Without trading with the surface for grains or the creation of a low light growing grain I am not sure how an underground city would feed itself. Now since we are talking about a pre-industrial society then all the [many uses of urine](http://www.smithsonianmag.com/science-nature/from-gunpowder-to-teeth-whitener-the-science-behind-historic-uses-of-urine-442390/?no-ist) come into play as a cleansing agent, dye, making leather, gunpowder (if they have that), and so forth. Pee from cities used to be quite valuable. [Answer] The underground city dwellers actually face some of the same issues as a spacefaring civilization. They live in a contained environment with limited resources and little ability to intake or expel things. Like a space colony, we can actually solve both problems to some extent by combining them. Underground city dwellers use a system similar to ancient Japan (where lower class individuals would collect waste from what amount to outhouses and used it as fertilizer). Dung carriers collect the waste and bring it to special caverns set aside as fungus gardens. Species of fungi have been carefully selected and bred for the purpose of efficiently converting waste into organic matter. This fungus is then either processed directly or fed to an intermediate stage animal like fish, and then becomes a food source for the city. In short, they eat their waste. [Answer] # Reduce the amount of poop by not pooping in the first place This question is directly tied to the question of what do underground dwellers eat. Well...what do they eat? Mushrooms? Bugs? Each other? A true underworld ecosystem like a [Menzoberranzan](http://forgottenrealms.wikia.com/wiki/Menzoberranzan) won't have many plants; in-fact I think moss is the only such plant mentioned in Forgotten Realms, as food for a underground [herd beast](http://forgottenrealms.wikia.com/wiki/Deep_roth%C3%A9). In any case, you are looking at mostly fungus, bugs, and cave seafood in your diet. That's not all bad. Removing plants from your diet removes the need to digest a variety of strange things that are found only in plants (like starch, for example). Fungus and animals are more closely related to each other than plants, so the GI tract of underworld dwelling creatures could specialize in things found in just fungus and animals. Also relevant, is that if you eat fungus, insects, and crustaceans, most of the 'hard' material that you have to digest is chitin...develop a way to digest that and you are in business. If your GI tract is very efficient, then you might not need to eat that much, and you would poop even less. So in addition to the other answers of the poo being used to fertilize underground gardens, it is entirely possible that there won't be that much poo to take care of in the first place. --- Edit for doubters: Here is more poop knowledge than you ever wanted. You poop 1 ounce per day for every 12 lbs of you. So lets say the average person is 120 lbs, and poops 10 ounces. Now cut that to 2 ounces, and multiply by a city of 10,000. That is a 1250 lb a day. That really isn't that much. One dude with a shovel and a wheel barrow can move that much easily. 10 dudes could clean up a whole city, and move poop to gardens. I argue that there is a very plausible explanation of reducing poop to quantities that are easy to manage. ]
[Question] [ I am writing a novel. In that novel, humans have settled a [tidally locked](https://en.wikipedia.org/wiki/Tidal_locking) planet. That planet is positioned at just such a distance from its sun that the sun heats the planet to an average of 25 °C at the [substellar point](https://en.wikipedia.org/wiki/Subsolar_point), that is, at the center of the side facing the sun. The planet is like our Earth in size, composition, and atmosphere. As that planet is tidally locked, the permanently dark side is much colder than the side that is in perpetual daylight, perhaps even freezing, with the coldest point on the opposite side of the substellar point. How far around the planet from the substellar point is the [0 °C isotherm](https://en.wikipedia.org/wiki/Freezing_level)? --- Looking at average temperatures on Earth, either for a specific month or the whole year, the distance between a place with 25 °C and a place with 0 °C always seems to be somewhere around 40° to 50° (e.g. from Mexico to Northern Canada in July). So I would suspect the 0 °C isotherm to be about 45° from the substellar point. [![enter image description here](https://i.stack.imgur.com/E3EsA.png)](https://i.stack.imgur.com/E3EsA.png) [Answer] This is just a basic answer, but I used [Samuel et al. (2014)](http://www.aanda.org/articles/aa/pdf/2014/03/aa21039-13.pdf), who in turn cited the climate model of [Léger et al. (2011)](http://www.sciencedirect.com/science/article/pii/S0019103511000534#) for a tidally-locked planet with no atmosphere. They give the formula for surface temperature as $$T\_s=\left(\frac{\epsilon\_5}{\epsilon\_2}\right)^{\frac{1}{4}}\left(\frac{R\_\*}{a}\right)^{\frac{1}{2}}T\_\*\cos^{\frac{1}{4}}\theta\tag{1}$$ Substituting in $T\_s=298$ (in Kelvin) and $\theta=0$ means that $$\left(\frac{\epsilon\_5}{\epsilon\_2}\right)^{\frac{1}{4}}\left(\frac{R\_\*}{a}\right)^{\frac{1}{2}}T\_\*=298\text{ K}$$ Therefore, we get an easy formula for $\theta$: $$\theta=\arccos\left[\left(\frac{T\_s}{298\text{ K}}\right)^4\right]\tag{2}$$ If we set $T\_s=273$, we then get $\theta=45.25°$, which happens to be almost exactly what you predicted. A very similar derivation of $(1)$ equation can be found [here](http://www.dangermouse.net/gurps/science/temps.html), although that $\theta$ is latitude, not the same as our $\theta$, and so $\sin\theta$ should be replaced by $\cos\theta$, leading to the above formula. A related equation is given such that the change in temperature from the greenhouse effects can be added in. I think we can do the same thing here: $$T\_s=\left(\frac{\epsilon\_5}{\epsilon\_2}\right)^{\frac{1}{4}}\left(\frac{R\_\*}{a}\right)^{\frac{1}{2}}T\_\*\cos^{\frac{1}{4}}\theta+\Delta T\_s\tag{3}$$ where we can compute $\Delta T\_s$ assuming that it comes from [radiative forcing](https://en.wikipedia.org/wiki/Radiative_forcing): $$\Delta T\_s=\lambda\Delta F$$ given the climate sensitivity $\lambda$ and radiative forcing $\Delta F$. I wrote about this in a lot more depth in [this answer](https://worldbuilding.stackexchange.com/a/40054/627). To accurately calculate both $\lambda$ and $\Delta F$, we need to know a lot more about the planet, its atmosphere, and its crustal composition. Drawing from my previous answer, if we knew the concentrations of various greenhouse gases, we could use a table from [the IPCC Second Assessment Report](https://ipcc.ch/ipccreports/tar/wg1/pdf/TAR-06.PDF) to calculate the relevant $\Delta F$s. However, that would require a lot of guesswork on my part. Now, perhaps we could neglect the greenhouse effect entirely. [Yang et al. (2013)](https://arxiv.org/abs/1307.0515) write > > The greenhouse effect for tidally locked planets is much smaller than those for non-tidally locked planets (Fig.2d). This results from a low-level temperature inversion on the nightside of tidally-locked planets (see also Joshi et al. 1997; Leconte et al. 2013). The inversion is due to efficient radiative cooling by the surface on the nightside and strong atmospheric energy transport from the dayside to the nightside (Merlis & Schneider 2010). The outgoing infrared radiation to space is therefore similar to the near-surface upward infrared radiation, resulting in a small $G$. > > > Here, $G$ is a parameter - a temperature difference - between the upward infrared fluxes at the planet's surface and at the top of its atmosphere; it's essentially $\Delta T\_s$. The difference in how important $G$ is is shown in the author's Fig. 2: [![enter image description here](https://i.stack.imgur.com/xQkBK.png)](https://i.stack.imgur.com/xQkBK.png) The 1:1 data points are for a tidally locked planet with clouds; the 2:1 and 6:1 points are for slightly faster rotators and the other two tracks are variations on the tidally locked model. See how the track without clouds has an extremely large greenhouse effect. Perhaps, then, at most stellar fluxes, we can neglect the greenhouse effect on our tidally locked planet. Something assumptions I'm still making: * There is little to no atmospheric circulation. * The surface is approximately homogeneous. Take this answer (v1) with a grain of salt. It's only a really, really basic approximation. [Answer] **As of right now, this is a partial solution** I set up a solution using a non-linear, non-separable first order differential equation. I ran out of brainpower midway through this post, and can't solve that right now, but I will revisit it later. If someone else can solve first, please edit this post. I wanted to post what I had, in case anyone can find errors now, and to re-type my notes more legibly. # Principles Assume that heated air rises at the sub-stellar point and proceeds at high altitude equivalent to Earth's stratosphere towards the poles, where it enters the 'dark side', a cool, infinite heat sink and heat source. Cool air from the 'dark side' returns in the surface layer equivalent to our troposphere. It moves towards the sub-stellar spot, heating up along the way as it absorbs solar radiation. We will calculate the energy balance of this surface layer of the atmosphere to calculate a delta-T as a function of angular distance from the sub-stellar spot. The angular distance where delta-T = -25 is the answer to the question. # Data and simplifying assumptions Data on radiation and atmopsheric circulation taken from [here](http://www.goes-r.gov/users/comet/tropical/textbook_2nd_edition/print_1.htm). This reference will be referred to as Fig. X of data. No land-sea interface; that is, the planet is either all land or all ocean. No heat transport from ocean circulation. Insolation at the sub-stellar point is equivalent to earth's equator. Heated air rises at sub-stellar and travels towards the dark side in the upper atmosphere. Cold air returns from the dark side in the lower atmosphere. The 'dark side' is an infinite, constant low temperature heat source for returning winds. Ignore effects of expansion and contraction of air when approaching and departing sub-stellar point. We will calculate atmospheric delta Ts from radiation balance in two bands, an upper atmosphere band, and lower atmosphere band. Atmosphere is mass $5.15\times10^{18}\text{kg}$, surface area of earth is $5.10\times10^{14} \text{m}^2$ for air column mass of $1.01\times10^{4} \frac{\text{kg}}{\text{m}^2}$. Lower layer is equivalent to troposphere, everything from sea level to 10 miles, with 75% of the atmosphere's mass, with air column density 7.5 $\frac{\text{kg}}{\text{m}^2}$, Upper layer is rest of atmosphere, air column density 2.5 $\frac{\text{kg}}{\text{m}^2}$. From figure 1.3 of data, 0.67 of energy absorption is from surface, 0.33 by atmosphere, of which 0.25 is lower layer (by above definition) and 0.08 by upper layer. We will simplify that all absorption is in lower layer. Assume solar energy absorption and radiation to space are the dominant means of energy transfer. Ignore heat transfer between upper and lower layers. Assume isometric heating and cooling, specific heat of air is constant 718 $\frac{\text{J}}{\text{kg}\cdot\text{K}}$. # Calculating Energy Balance for the Lower Atmosphere Simplifying Fig 1.7 of data, Incoming radiation is 300 W/m^2\*month at the 0 from substellar, 0 at 90 from substellar, and linear in between. Temperature change due to energy input is: $$E\_{in} = \frac{300 - \frac{10}{3}\gamma\,\frac{\text{W}}{\text{m}^2}}{7.5\frac{\text{kg}}{\text{m}^2}\cdot718\frac{\text{J}}{\text{kg}\cdot\text{K}}} = 0.0557 - 0.000619\gamma\, \frac{\text{K}}{\text{s}}\quad\quad 0^\circ < \gamma < 90^\circ$$ where $\gamma$ is the angle from the sub-stellar point Simplifying Fig 1.7 of data, Outgoing radiation is 250 W/m^2\*month at 0 from substellar, since temperatures are similar to earth's at the equator. By Stefan Boltzmann law, radiative heat transfer is proportional to the fourth power of Temperature. Temperatures must be calculated in Kelvin. Temperature change due to energy output is: $$E\_{out} = \frac{250 \left(\frac{\text{T}}{298}\right)^4\,\frac{\text{W}}{\text{m}^2}}{7.5\frac{\text{kg}}{\text{m}^2}\cdot718\frac{\text{J}}{\text{kg}\cdot\text{K}}} = 5.9\times10^{-12}T^4 \, \frac{\text{K}}{\text{s}}$$ where $T$ is temperature in Kelvin. # Wind Speed and Pressure assumptions Changes in temperature drive changes in pressure which drive changes in wind speed which drive the temperature gradient. To avoid solving three simultaneous differential equations, ignore the effect of pressure changes on wind speed. We will model the expected strong, constant winds at 10 m/s and 20 m/s. A degree of latitude is 111 km. The ratio between distance and angle is $9.0\times10^{-6}\frac{\text{degrees}}{\text{m}}$. A translation of the above wind speeds to angular velocities is $9.0\times10^{-5}\frac{\text{degrees}}{\text{s}}$ and $1.8\times10^{-4}\frac{\text{degrees}}{\text{s}}$. # Differential Equation and Solution(?) Overall energy balance for the atmopspheric circulation is, after converting angle to time using the 10 m/s wind speed: $$\frac{dT}{dt} = 0.0557 - 5.6\times10^{-8}t - 5.9\times10^{-12}T^4$$. ## EDIT: After attempting to solve numerically using an Euler method, I discovered that this does not work. My problem is ignoring the potential energy imparted to air molecules to raise them from the lower atmosphere to the upper atmosphere. This takes something like 5e8 W at the 10 m/s flow I calculated and needs to be accounted for. Still working. [Answer] I'll try a simple answer. I didn't see the call for hard-science facts, so i thought i can give it a try. I didn't do a master in physics, and i do neither have the time nor the possibility to program a weather simulation that would most certainly be required to give you a correct answer. Let me say this right away: this answer is not really hard-science, but i tried my best. I will try to answer your question by following these steps.: 1) How is temperature distributed on a tidal-locked planet? Do we have real life examples? 2) How does having an atmosphere influence temperature distribution? 3) Which temperatures are required for a planet to carry life? 4) Where is our isotherm point? ## How is temperature distributed on a tidal-locked planet? Do we have real life examples? Let's start by looking into planet that is close to ours: mercury. Mercury has almost no atmosphere, and the temperatures there range from 100K to 700K, while the poles are constantly <180K. Mercury has almost no axial tilt, and it is actually almost tidally locked. So Mercury gives us a good representation of how the temperature would distribute on our planet without an atmosphere. Mercury is smaller than earth, but since you haven't specified a size for your planet, we will ignore size completely. How would your planet behave if it had no atmosphere? We could just put in your maximum temperature of 295K as a max, and downscale everything in relation to that. We would have a maximum of (logically) 295K with a minimum of 42K, and the poles would be at roughly <74K. Brrr.. that's fresh. Given that pluto has a mean temperature of 44K, a temperature where most gases just instantly freeze, our planet would be really really cold on the dark side. ## How does having an atmosphere influence temperature distribution? Atmospheres are useful. They help spreading the overall temperature more evenly, or even raise it. Venus has an average (!) surface temperature of 735K, which is equal to the max temperature on Mercury. Which is muuuch closer to the sun. Damn greenhouse effects. So the atmosphere, which our planet requires, since humans settled on it, will change the overall temperature distribution, as well as max or min temperatures. Since our max temperature was probably taking atmosphere into account already, we need to raise our minimum temperature. But.. to which level? And how would the temperature distribution change? I googled a bit and found this document: [Document](https://arxiv.org/ftp/arxiv/papers/1405/1405.1025.pdf) The document i linked suggests that if the temperature drops too low, the gases in the air freeze, leaving a vaccum. The low preassure causes the air from the warm side to expand, spread to the cold side, and freeze, too. So the planet wouldn't have any atmosphere. To avoid this, we require strong winds that help spreading the temperature so much, that the gases on the cold side can't freeze. But there are no formulas available to me to estimate how EXACTLY the temperature would behave. That depends on the strenghts of the winds, geological and climating conditions, the exact distance from the sun, gravity, magnetic fields, the evolution of the planet etc.. But i know that the temperatures need to be high enough so our gases don't freeze, even on the dark side. ## Which temperatures are required for a planet to carry life? Our atmopshere is primarily composed of Oxygen, Nitrogen and Carbon dioxide. The freezing point of these are: Oxygen freezes at: 54 K Nitrogen freezes at: 63 K Carbon dioxyde freezes at: 195 K All of these should constantly exist as a gas, otherwise we might suffer from atmosphere drain (or life would change very VERY drastically), especially considering that Co2 is a primary catalyst of greenhousing and thus: warmth. We need that stuff in our atmosphere, if we want it to be able to keep our temperatures more civil. Okay, so 195K seems like a good temperature to set as a minimum. Let's notch it up to 200K, just to be sure, and to allow fantastic "carbon dioxide rain" on especially cold nights on the dark side....just to be sure, 200K is still -73C, and thus VERY cold. This is the temperature we require at least on our dark side. It might be higher on your planet, thus changing all the results of my calculations. I dare say: your question doesn't have a definitive solution. ## Where is our isotherm point? I think it is safe to say we now have our three points of temperature we require for our calculations: Max: 295K (as defined by OP) Minimum: 200K (as calculated above) Temperature at poles: <212K (as calculated from situation on mercury) 0C is 273K, just by the way. Now, for the calculations. If the temperature was distributed "evenly", it would drop from 295(substellar point) to 212 (poles) evenly. It probably doesn't, but as i said, the strength of the winds, the unknown geology and other factors make it impossible for me to give a precise estimation. If the substellar point is at latitude 0, and the poles are at latitude 90, and we have above temperatures, our point of 0 degrees Celsius would be at a latitude of: **23,86 degrees....** It depends strongly on the direction of the winds, though. If I assume the winds move around the planet in one direction, the 0-point will be much closer to the substellar point in one direction, and much further out in the other. [Answer] Just to add to the answers that are here: I'm surprised that no one referred to [this question](https://worldbuilding.stackexchange.com/questions/4850/how-would-winds-behave-on-a-tidally-locked-planet). Based on the above mentioned answer about atmospheric winds due to heating, it looks like there may be super-rotation, perhaps like a sub-stellar vortex. Lots of storms and a good deal of heat transfer. This suggests a quite active weather system, interesting perpetual winds and possibly a bit larger +0°C region. I cannot comment on how much larger the +0°C region may be, but it seems as though, with a large area of the planet cold enough to collect ice over millions of years, that most of the water on the surface would be trapped and the result would be very dry air circulation and perhaps desert like conditions around the sub-stellar point and more likely some rain at lower sub-stellar-latitudes. I could foresee large circulating dust storms up to very near the sub-stellar point. ]
[Question] [ So a zombie outbreak finally happened, but it's not like it is in the movies. Instead of craving the taste of human brains, those infected with zombiism simply want to shamble along, occasionally groaning, and on rare occasions forming herds. There is some indication that zombies enjoy the same things they enjoyed when they were 'alive', but this has not been proven, and for the most part zombies seem to have lost most or all of their former personality and memories. Getting bitten or scratched by a zombie still has a very good chance of passing the infection to you (as long as actual blood is drawn), and as can be expected there is no cure. When not being spread through blood contact, the zombie virus seems to infect the recently deceased and those with severely deficient or depleted immune systems. Zombies live about as long as a dog, ten to twenty years depending on the health of the host, but during this time they still need food, water, and oxygen (albeit a smaller supply than a regular human would need). They appear to be completely resilient to disease, and injuries barely phase them. They show some emotions, and seem to have basic intelligence, but things like stairs are a large mental effort for them, and they do not seem to be able to form new memories. What I'm wondering, though, is if, say, 15% of the population caught the initial strain, and now are zombies, how would the rest of society react? What adjustments would be made to laws and daily operations in order to account for zombies? What might be done to contain these shambling hordes? Are there any real-world examples to extrapolate from? I'd appreciate both/either the short-term and long-term implications. Let me know if I left anything important out. [Answer] ***Disclaimer :*** I will address a rather sensible subject in that answer (disability), since I am not a native English speaker the subject may be treated in terms seemingly disrespectful (Google translate is unhelpful in that domain). It is obviously not my intention, so if it appears to be the case, please consider suggesting an edit. First of all, zombies will **not** be labelled as zombies at first. It looks like a mere detail, but as long as you consider them as people, sick and highly contagious people, but still people, no strategy looking like "kill them all" will be adopted. Because we do not fight against disease by killing the infected (as far as I know humans have never done it). Anyway, lots of them may die in the first weeks (as pointed out by AndreiROM) due to the lack of survival instinct and stupidity, but lots of them will also take cared of by their family or friends and be brought to the hospital (they just look strangely sick). Of course, investments will be made to search for a cure, because there will be no reason to thing that a cure may not actually exist. The amount of investment will heavily depend on the affected countries. On a longer term, it is probable that zombies will be treated as we actually treat heavily disabled people, or people suffering from dementia. Somebody needs to take care of them constantly, for example to help them feed themselves or to avoid them harming themselves. It can be done by the family, but due to the contagious aspect of the disease, it is likely that specialized institutions will be used the most. The point is that human beings not having, losing, or being unable to fulfil independently they survival instinct is not new. We already have institutions, help centers and even sometimes traditions to help deal with it. The real problem here is the scale. It is about 15% of the population, meanings two things : 1. The workforce will be greatly reduced, crashing the economy. 2. Lots of infrastructure will be needed. I will not address in details these problems here. However you can see that the second point can have two very different outcomes, since taking care of all these zombies will cost a lot of money : 1. The governments accept to pay for the cares needed by the zombies. This will probably lead to the eradication of the disease over the next decades. 2. They don't. That means poor people will take care of they zombies themselves, increasing the chance of the epidemic to spread. In the second scenario, and on the long run, since only a part of the population is affected, zombies may be dehumanized and exterminations may be envisaged. But there would be opposition from the relatives to these zombies. [Answer] The classic "zombie outbreak" involves zombies rising from the grave, then spreading their zombie plague through bites. Those bitten soon turn into zombies themselves, further spreading the plague. The key here is the *violence*. Traditional zombies change from normal people into homicidal monsters, shrugging off pain and injuries and murdering anyone that gets close enough. Your zombies, however, are not violent. I posit that your zombies aren't, in fact, zombies at all, but merely normal humans who have suffered some sort of brain injury, brought on by a virus. A symptom of the disease is a period of ultra-low heart rate and breathing, which leads to drastically reduced brain waves, which then leads to many people to be declared dead. When the dead rise, it is after their body has fought off the infection. Unfortunately, the permanent mark of the infection is brain damage: the pain receptors, memory centers, and higher functions destroyed, or nearly so. The result is a shambling, drooling, moaning creature, only a shadow of its former self, able to walk and perhaps eat when food is in front of it, but not much else. In the **short term**, this disease will be classified as just that - a highly infectious disease. In most first-world nations, the infected will be rounded up and placed under guard in hospital clean-rooms as a cure is sought. Of course, there is no hope for the infected - once the disease has run its course, those left are permanently brain-damaged. Poor nations will probably kill the infected and burn the bodies, trying to eradicate the disease. Since the disease is spread through blood, and the infected tend to be fairly passive, few will be infected. If that is the only route of infection, then in the **long term**, the disease will die out, eventually only remaining in laboratories. [Answer] What about organ-farming? At least based on most movies, zombies have incredibly powerful regeneration abilities. So how about you do something like this: you take sections of certain organs, cut pieces out, then nuke it with an enzyme toxic to viruses and bacteria but undamaging to human cells. Such enzymes (sort of) exist: restrictor enzymes. They slice up DNA at a certain point. So all you would need to do is sequence the viral DNA, and find appropriate restrictor enzymes. Also, this provides an excellent ability for fighting crime. You could use the zombies for a few things: armed suspect extraction, and interrogation. I am certain that one of the greatest fears of a human would be to become zombified. So when a person is strapped down with a hungry zombie on a leash 3 inches from his face, I think they'll spill the beans faster than an inexperienced worker at a Mexican restaurant. When it comes to armed suspect extraction, its just as simple as teaching a zombie how to use a gun, or if this is impossible, just use a lot of zombies! Apart from the fear factor that may prompt the suspect to surrender, the zombies are unphased by injuries and would, therefore, make very useful soldiers. [Answer] The zombies are still a carrier. So there is some inherent risk to keeping them around. However, if they are mostly harmless then I would expect any who want to keep their loved ones as 'pets', cleaning up after them, feeding them walking them, etc. I would also expect them to have regular blood tests to make sure they haven't caught the disease yet. For the rest, try and find something for them, Maybe put them in hamster wheels attached to generators, let them produce electricity and be useful. They don't even have to go fast if there are enough of them. They would be cheap to feed and water. And it would make some use of them. Just killing them off would be expensive and time consuming no matter how your do it (just ask the Nazi's). Unless you created a power generator that burned zombie bodies for energy, and I suspect that having them walk into the fire pit would be to cruel even for non-liberals, so you'd still have the issue of a 'humane' death before incineration... [Answer] Extermination seems like the only reasonable response in my mind. While not aggressive the zombies still present a large potential threat. **A couple options come to mind.** 1. **Purge:** Just exterminate every single one of the zombies. No muss, no fuss, send in a clean-up crew with flame throwers. 2. **Exterminate/Experiment:** Destroy most of them. Then, like nuclear technology I can see governments doing research into the weaponization of the zombie virus. This would of course end horribly for everyone. Additionally terrorist organizations may drop zombies into population centers and wreak havoc. 3. **The zombie farm:** Use the virtually free labor for simple tasks. Its very *green* energy after all. Utilize zombies as free labor where basic motility is all that is required. This is also not a particularly good idea...but bad choices make for good stories. I would just add that, I would not want to keep an infectious shell of a former family around for sentimental reasons. Now, I can see a trade springing up if the zombies were not infectious, or perhaps they are only infectious for 6 months at which point they are harmless simpletons, but even then I wouldn't do that to a family member...well maybe one or two but not most of them. [Answer] Assuming that in the beginning, people only turn into zombies if they die, not just randomly (not sure about this.) Some people will want to keep the zombie around for sentimental reason, but most people won't--for them, t zombie can be just another mouth to feed, with no labor or fun or anything coming out of it. The economy will not crumble to dust, but millions could become unemployed if zombies are used for cheap labor (and even if they aren't, every funeral home will go out of business.) Zombies will be extremely prejudiced against, have no rights, and be segregated, but no zombies will rise against this. There will be frequent zombie massacres, and many zombies will be sold as slaves. There will be a small movement for zombies' rights, but nobody will listen. Some zombies will be studied in labs, but as their numbers grow, they will all be either slaves or dead. Some evil rich people will kill humans, then use their zombies as slaves. Dead zombies will pile up, and with no funeral homes, eventually become just another pile of rotting stuff. They will rarely infect anyone, since they are not violent. The economy will fall but slave labor will take its place, leading to a much bigger class division. This will lead to higher death rates of the lower class, leading to more zombies...eventually, the world will be taken over by multitrillionares and their armies of zombies, forced to fight (organs/bows and arrows shooting zombie fingernails or something like that). [Answer] The zombies themselves are not threatening, but *whoa* is that disease scary! That will be the governing consideration. I base this on how people react to outbreaks of deadly diseases (and that's how this will be viewed, as a deadly disease) now. Healthy people will place high priority on protecting themselves from carriers. Zombies will be quarantined, by force if necessary, and the people who take care of them will take extra precautions to avoid physical contact. Think about the reactions to the ebola outbreak of 2014-2015, and that involved a *much* smaller proportion of affected people. Even once it's determined that transmission isn't airborne or by touch but requires actually drawing blood, there will still be stigma. Think about how people with HIV were treated when the disease first became known -- and how some are treated even today. And, again, we're talking about a much smaller population and a means of transmission that is, shall we say, far from "casual encounter". With 15% of the population affected by an incurable, spreadable disease, and especially if those people's minds are gone anyway, I think society's reaction will be to round them up, put them in special facilities "for their own good", and keep them away from everybody else until a cure is found or the plague dies out. They're still human beings -- or, at least, you don't know that they *aren't* -- so, while some will call for "putting them down" for the good of humanity, western sensibilities will not support that position. But fear of the disease would make it very difficult for those who want to integrate zombies into everyday life. ]
[Question] [ Something has gone horribly wrong in Mundus, a fairly standard medieval fantasy world. A rather eccentric wizard was carrying out some research and one of his spells blew up in his face, causing a catastrophic event: throughout the world, every sentient being--humans, elves, dwarves, dragons, even the Gods--suddenly vanishes all at once, caught up in the wild magic and instantaneously carried forward in time by approximately 300 years. When they emerge, after a brief but intense period of vertigo, they find they're in the same place as they had been, their clothing and anything they had on their person is still intact, but the rest of the world has lived through those 3 centuries the normal way! Non-sentient life (plants, animals, microbes, etc) was not affected (directly) by the spell. What kind of challenges do they face, trying to re-establish society? They would not have as difficult a time as we would today, as there was less advanced technology to be dependent on, but all of their cities and dwellings would be in ruins to one degree or another by this point. Note: Just to keep things simple, at the time of the Catastrophe, no one in the world possessed any industrialization or large-scale magic capable of causing significant changes to long-term climate patterns. [Answer] A fair number of them will die immediately. * Any sailors in the open sea will pop into existence above the water where their ship used to be (or worse, where their ship is now, most likely underwater). * Some will pop into existence inside the crumpled remains of their home or in the air where the upper floor of a building used to be. * Some will suddenly be in flooded cities or trapped in dense forest. * Any swimming in a river before might suddenly find themselves swimming under a riverbank. * If the gut bacteria are considered non-sentient and left behind, most of the population will have some difficulty with digestion. Some will benefit from such a thing: * Hunter gatherers might find all the game and plants will be suddenly replenished. * Prisoners will find their cells rusted away, allowing them to escape. * Individuals in debt may no longer have any records against them for their debts. * Again if the bacteria/viruses are not transported with their hosts the diseased and sick will find themselves cured (though will have trouble with digestion). The survivors will begin to rebuild. As you mention, the less advanced civilizations will fair better, because they rely less on existing infrastructure. For the more advanced societies they'll have trouble with their failed infrastructure. Any information written down on scrolls or parchment will likely not exist anymore. Though many will retain land or titles because everyone still has the memory of their status. Still, many land grabs and bank runs will occur. Cities which required bridges for access, walls for protection, or aqueducts for supplying water will find themselves in a very bad position. Things will kind of go to hell for a while, but enough knowledge and skills are retained in memory that the rebuilding won't be as detrimental as it would be for a society like ours. [Answer] Everyone just reappears right where they were, but everything is in three hundred years of disrepair? I imagine everyone would just begin the process of rebuilding. I don't know the inner workings of this world, but I imagine a band of warriors from the collective races would travel together to seek vengeance on this wizard; no one is going to be happy with him. Rebuilding will probably take years; medieval infrastructure is largely based on agriculture. The farms will been overrun with local flora, but they will have to be first priority. Most metal tools and weapons will likely still be useful to some degree. Anything that wasn't built from stone will surely be too ruined to bother repairing. It'll be more effective to simply move the ruins and build a new structure in its place. I doubt the dwarves will be too negatively effected. If the stereotypes and motifs I have in my head about fantasy/medieval imagery are correct, they like to live in mountains and oftentimes have large pseudo-industrial infrastructure in place that can last centuries of dormancy. Elves always seem to live in magical wooded areas, I'm sure whatever magical properties their homes had three hundred years ago won't have degraded too severely, given their life spans. Their homes will probably be massively overgrown, but I doubt they'll have too much trouble taking care of that. Humans are an innovative and hardy race. They'll probably rebuild their society just a little better than it was before. They always seem to be interested in progress. Dragons would what, reappear on their piles of treasure? I doubt the gods would be too upset, depending on how powerful they are and how involved they are in the workings of this world. They'll probably laugh at the puny wizard playing with such powerful magic and messing up. As gods they shouldn't have a problem with reversing it, but it's more fun to just sit back and watch everyone scramble to put things back how they were. [Answer] As correctly pointed by first answers, not all "Time travelers" could to survive. In deed, most of the "travelers" will die, mostly by famine. A 90% or more death toll is expected! But to the survivers the experience will no be too much diferent from a long distances migration, in instance, one like 10,000 years ago humans were obliged to do because the start of the Ice Age. ]
[Question] [ Countryistan is a large island nation approximately 3,000 kilometers from the nearest landmass. The government of Countryistan is secretly planning on committing genocide and ethnic cleansing against a portion of its population in about a decade. A powerful billionaire/member of the ruling party who's secretly sympathetic to said portion of the population, and who knows what's going to happen, happens to own an oil company which owns an [ultra-large crude carrier](https://en.wikipedia.org/wiki/Oil_tanker#Size_categories) - a huge ship designed to transport enormous quantities of unrefined crude oil. Said ULCC is currently in a high-quality shipyard specially-built to accommodate it. It is intended to leave within a year or two on a shakedown cruise to a nearby country; however, the billionaire and the higher echelons of their company are constantly sabotaging it in order to cause enough of a delay for it to be retrofitted. Said billionaire wants to turn said ULCC into a transport, fill it with the people most likely to be murdered by the government, and then send it on its 3,000-kilometer cruise. Once it and its passengers arrive in a safer place, it simply won't come back - or, maybe it will, minus its passengers, and it'll just keep going back and forth until the plot gets found out. This billionaire and their company have the resources to keep government inspectors away from the ship - they own a good portion of the country's shipbuilding industry, but have little power otherwise due to deliberate factionalism within the ruling party. They can do many things covertly, however; money talks. For the purposes of this question, the ship is the [Seawise Giant](https://en.wikipedia.org/wiki/Seawise_Giant). It has the following characteristics: * Full load displacement: 657,019 metric tons (646,642 long tons) * Capacity: 4.1 million [barrels of oil](https://en.wikipedia.org/wiki/Barrel_(unit)) ([574,000 metric tons of oil](https://www.unitjuggler.com/convert-energy-from-boe-to-koe.html?val=4100000), or [somewhere between](https://www.google.com/search?q=density%20of%20oil&oq=density%20of%20oil&aqs=chrome..69i57.2146j0j1&sourceid=chrome&ie=UTF-8) 604,211 and 820,000 cubic meters of oil) * Length: 458.45 m (1,504.10 ft) * [Beam](https://en.wikipedia.org/wiki/Beam_(nautical)): 68.6 m (225.07 ft) * [Draft](https://en.wikipedia.org/wiki/Draft_(hull)): 24.611 m (80.74 ft) * Depth: 29.8 m (97.77 ft) * Speed: 16.5 [knots](https://en.wikipedia.org/wiki/Knot_(unit)) (30.6 km/h; 19.0 mph) Additionally, it is [nuclear-powered](https://en.wikipedia.org/wiki/Nuclear_marine_propulsion), with a reactor/turbine combination that puts out as much horsepower as the real-life *Seawise Giant*'s engines. In-universe, this is seen as perfectly normal and not suspicious. **It does not require refueling within the timespan of this question.** **How do we modify this ship to carry the maximum number of people possible, taking into account the following conditions?** * **The ship has to look the same on the outside as it would if it were unmodified - both above *and* below the [waterline](https://en.wikipedia.org/wiki/Waterline).** There can be no extra structures on the deck, no holes in the hull, and nothing, visually speaking, that gives away the fact that the ship is full of refugees, or, for that matter, invites any form of suspicion. * **The ship has to [displace](https://en.wikipedia.org/wiki/Displacement_(ship)) roughly the same amount as it would if it were empty and unaltered**, because, if it rides too low or too high in the water, it'd be suspicious-looking. A small margin of error is acceptable here. * **The ship has to move as quickly as it would if it were empty and unaltered,** since if it was moving slowly, it'd draw suspicion (and also require more supplies for the refugees). This means 16.5 knots, bar a small amount that could be explained away as engine trouble. * **Anything that does not change the outside appearance of the ship, its displacement, or its speed is fair game.** For instance, the guts of the ship can be pulled out and replaced with their weight in people and supplies for said people, and blocks of concrete or steel can be put on board in order to add enough weight to make it settle in the water correctly. * People should not die en-route, other than by accident or things they were already going to die of. If someone dies of cancer, that's fine. If someone dies of dehydration, it's not. [It will take 98-ish hours](https://www.google.com/search?q=3000%20km%20%2F%2016.5%20knots%20to%20hours&ei=YVUDYtLLE5bE0PEP8cSv4Ao&ved=0ahUKEwiSgLHs9fH1AhUWIjQIHXHiC6wQ4dUDCA8&uact=5&oq=3000%20km%20%2F%2016.5%20knots%20to%20hours&gs_lcp=Cgdnd3Mtd2l6EAMyBQghEKsCMgUIIRCrAjIFCCEQqwI6BwgAEEcQsAM6CAghEBYQHRAeSgUIPBIBMUoECEEYAEoECEYYAFBzWKcTYPITaAFwAXgAgAFhiAHxBJIBATiYAQCgAQHIAQjAAQE&sclient=gws-wiz) for this thing to get from Point A to Point B, and probably another 12 on either end for loading and unloading. **No simply packing people in like sardines; there has to be enough room to sit down, enough below-the-deck restrooms for people to use the bathroom, adequate ventilation, food for about 5 days, etc.** It does not need to be comfortable, though; it just needs people to not die/go insane long enough for it to arrive on-target. * **Your budget for modifications is equivalent to $20 billion in present-day dollars.**. The ship itself, the nuclear reactor, shipyard, provisions, operating costs, and the like are all accounted for; this budget is *only* for modifications. The shipyard facilities are top-of-the-line. * To reiterate, **the nuclear reactor and the subsequent lack of exhaust are seen as perfectly normal**, and not suspicious. * **The ship is already fully built**. It will need excessive reconfiguring in order to serve its purpose. * **You have 9 years** to get these modifications finished. I believe this is reasonable, considering that *Seawise Giant* [was built within 5 years](https://en.wikipedia.org/wiki/Seawise_Giant). * **Getting these people on board isn't a problem.** The billionaire and the company just pretend to be killing the people, they disappear (in reality, via the ship) and the government doesn't figure it out. * **Getting these people off the ship isn't a problem either.** The billionaire and their company have set this up in advance. * **Assume Earth-standard conditions** - for instance, approximately 9.8 m/s^2 of gravity, 101.325 kPa air pressure at sea level, human-breathable atmosphere, seas made of water, etc. Additionally, **assume a modern-day tech level**. I will add more to/edit these requirements if someone points out a glaring absence in/flaw with them. And don't you tell me that anything less than 8,000 can fit on it once it's retrofitted; [the world's largest cruise ship](https://en.wikipedia.org/wiki/Wonder_of_the_Seas) can fit more than that, it's smaller than this thing, and its design prioritizes comfort over efficiency. [Answer] "It was sad when the great ship went down." Moter Vehicle *Wilhelm Gustloff* was sunk on 30 January 1945 and thousands of people drowned. > > The figures from Schön's research make the loss in the sinking to be "9,343 men, women and children".[22] His more recent research is backed up by estimates made by a different method. An Unsolved History episode that aired in March 2003,[4] on the Discovery Channel, undertook a computer analysis of her sinking. Using maritime EXODUS software,[23] it was estimated 9,600 people died out of more than 10,600 on board. This analysis considered the passenger density based on witnesses' reports and a simulation of escape routes and survivability with the timeline of the sinking.[24] > > > <https://en.wikipedia.org/wiki/MV_Wilhelm_Gustloff#Losses> Considering how many more people there were aboad than on a modern cruise ship, one might imagine that *Wilhelm Gustloff* was gigantic. *Wilhelm Gustloff* had a GRT of 25,484, and had a length of 208.5 meters (384 feet 1 inch), a beam of 23.59 meters (77 feet 5 inches), a height of 56 meters (183 feet 9 inches), and a draught of 6.5 meters (21 feet 4 inches). So it held 2 or 3 times as many people as a large modern cruise ship in only about 10 percent of the space. The passengers were mostly German refugees fleeing in terror from the advance of the vengeance-crazed Red Army, so they didn't mind being packed in. Of course the planned voyage of *Wilhelm Gustloff* was a much shorter distance than about 3,000 kilometers. I think that the planned voyage of the *Wilhelm Gustloff* would have been less than 300 miles or 483 kilometers. At a speed of 15.5 knots or 28.7 kilometers per hour, or 17.8 miles per hour, it should have taken less than 17 hours for the planned voyage, and possibly a lot less time if the destination was significantly closer than 300 miles or 483 kilometers. So the passengers would have been willing to be crowded and have inadequate facilities for such a short time. But the voyages in the story would be a lot longer, about 3,000 kilometers, at a speed of 16.5 knots, or 30.558 kilometers per hours. Such a voyage would take about 98.17 hours, or about 4.09 days. So the passengers would need much more food, water, and air, and much more facilities, for the voyage, especially if some of them were not in terror of being exterminated. Another historic example of a crowded ship is the Chinese junk *Tek Sing*, which sank on February 8, 1822. > > The Tek Sing (Chinese, "True Star") is one of the few "Asian vessels discovered in Southeast Asia [that we know its name, for] "generally neither name nor date is known. The Tek Sing is an exception."[1](https://en.wikipedia.org/wiki/MV_Wilhelm_Gustloff#Losses) Generally, shipwrecks are named either after a landmark or location near where they were found or the cargo they held. She was a large three-masted Chinese ocean-going junk which sank on February 6, 1822 in an area of the South China Sea known as the Belvidere Shoals.[2] The vessel was 50 meters in length, 10 meters wide and had a burthen of about a thousand tons. Its tallest mast was estimated to be 90 feet in height. The ship was manned by a crew of 200 and carried approximately 1600 passengers. The great loss of life associated with the sinking has led to the Tek Sing being referred to in modern times as the "Titanic of the East".[3] > > > So the *Tek Sing* was 50 meters (164 feet) long, and 10 meters (32.8 feet) wide. So the main deck of the *Tek Sing* should have had about 500 square meters. With about 1,800 people aboard that would give about 0.27777 square meters (2.99 square feet) per person. If it had 2 decks there would have been 0.55555 square meters (5.98 square feet) per person, three decks 0.83333 square meters (8.97 square feet per person) per person, four decks 1.11111 square meters (11.96 square feet) per person, 5 decks 1.3888 square meters (14.95 squae feet) per person. And maybe a lot less if the cargo of Chinese porcelain took up a lot of space that people could have occuptied. The *Tek Sing* was sailing, repeat sailing from Xiamen, China, to Jakarta, Indonesia a distance which I estimate to be about 2,100 miles or about 3,379 Kilometers. It sank in the Gaspar Strait, most of the way to Jakarta, after about a month of sailing. So the approximately 1,600 Chinese immigrants on the *Tek Sing* were willing to endure a month of sailing in crowded, unsanitary conditions on it, for several times as long, maybe 10 times as long, as the refugees in your story would endure conditions on their voyages. Of course if your world is advanced enough to build a late 20th century type vehicle the size of the *Seawise Giant*, the people in it might have become too refined and spoiled and dainty to endure such conditions even to save their lives from genocide. Added Feb. 10 2022. The *Seawise Giant* was 458.45 meters (1504.10 feet) long and 68.6 meters (225.07 feet) wide. So its deck area was approximately 31,449.67 square meters or 338,57.78 square feet. That is approximately 6.394 times the approximately 4918.515 square meters of the *Wilhelm Gustloff*'s deck area and approximately 62.899 times the approximately 500 square meters of the *Tek Sing*'s deck area. If it has as many decks as the *Wilhelm Gustloff* and is as crowded as the *Wilhelm Gustloff*, it could carry approximately 67,777.875 people. If it has as many decks as the *Tek Sing* and is as crowded as the *Tek Sing*, it could carry about 113,218.81 people. And those rough calculations might give an idea of the approximate upper number of people who could be carried under some conditions. [Answer] If we go with a useable volume of 600,000 m³, based upon the ship's crude oil carrying capacity, we could allocate 1 ton and 2 cubic metres per person that it will be refitted to carry. This is approximately the same volume allocated per man in age of sail warships... which would likely be a bit too cramped when AoS crews could get out of their hammocks and do a bit of outdoor manual labor, but these refugees must stay inside. Allocating 1.5 tons and 3 cubic metres per person would include a bunk bed, provisions, shared head/mess/galley/recreation areas and nuclear powered air conditioning. The sleeping arrangements would be cramped, and the recreation areas wouldn't be terribly large, but they'd allow the passengers to get a bit of exercise and avoid DVT from long periods of inactivity. The food would be largely pre-packaged and bland, but it would keep the passengers alive for a couple of weeks, more than twice as much as expected. So, with 600,000 m³ of volume, we'd have space and supplies for 200,000 refugees. Allowing 2 tons and 4 cubic metres per person for 150,000 refugees would approach the conditions experienced by passengers in steerage on an early trans-atlantic passenger ship (or better, considering that they wouldn't have air conditioning), and when the goal is to carry as many passengers as possible on a relatively short trip of 5 days, this may be a bit too much luxury. To make up for the difference in mass between passengers and its supposed crude oil cargo, the ship could take on ballast water. Modern ships are designed to do so, no refitting necessary. Refitting the ship for this purpose could easily be achieved in the allotted time of 9 years... probably in a third of that time, or less, and definitely for well under 20 billion. In fact, 1 billion would probably cover the costs nicely. I've also used the figure of 600,000 m³, less than that which the OP has said is available, in order to use the remaining volume to modify the ship's structure and if necessary its power plant, in order to compensate for the different mass distribution and higher power requirements, though the existing nuclear power plant should easily be capable of supplying the required power, since such plants are typically over-engineered in order to avoid stressing them. If this ship is intended to carry its passengers on its maiden voyage, and it needs to look unloaded, just move the plimsoll lines so that they're well above the loaded eaterline and run with minimal ballast. Move the plimsoll lines again for the return to dock to account for the altered load and take on ballast water, if necessary. [Answer] In order to have a plan like that you need to have a good idea of how many people you need to kill off, that means keeping close tabs on your general population and closer tabs on the ones you think you might want to do away with. In short the government have to run a fairly competent surveillance state to even consider this plan if people have any normal freedom of movement. Which makes the limiting factor not the carrying capacity of the ship, which I put at a minimum of 26,000 for the hold alone (that's based on how tightly they cram crew into a Skipjack nuclear submarine so the final total is going to be much higher; there are no weapons systems and they need far less provisions per head for the short trip overseas than a 6 month patrol), but how many people the company can spirit away to the ship before the death squads show up on the docks. [Answer] # It's easily possible The Seawise Giant (now Knock Nevis) is a double hull tanker. If we remove it, we'll have a lot of extra weight we can use. If we use lightweight materials like some carbon fiber polymers we can make a whole ship that approximates the right weight unladen. It is more difficult to make it correct when it should approximate fully loaded. The nuclear reactor can solve a lot of problems. You need sunlight lamps, air recirculation, purifying and some fresh air, cooling/heating, water purifying and more. All can be done with the nuclear power. It'll even make too much energy and easily power the engines as well. With all the piping on top of the ship it should be possible to make many connection pipes look closed, while they actually suck in fresh air or something. Under the ship you can have compartments that open and close to let in water you'll purify, reducing the chances anyone somehow looking under the ship will notice things aren't what they seem. There's 650.000m³ of space available. In submarines a person has about 1.4m² space, just enough for a bed and to store a fee belongings. Add a bit extra for xommon areas and facilities and we can come to about 2m² space per person. With a height or roughly 2m that is 4m³ per person. 650000/4= 162.500 people. Lets remove some for extra storage, facilities and maybe the exact measurement doesn't allow for an extra floor or something. Add in some extra space for the nuclear reactor that will probably need more space than the current engine and we'll have 140.000 people left as a very rough estimate. This is cramped, but there will be place for recreation, eating and other things. The only problem is that you either need to pretend the ship is never at carrying capacity or you need to have a lot of heavy ballast you can transport. Using lead or something you can add weight, but you'll lose a lot of compartments. Lead is about 8,7 times as heavy as oil per volume, so you would need 1/8th of your living space to be used for weight. This needs to be added and removed, possibly moved by other ships the other way again. That means about 122.500 people can come with. Still quite a lot. TL:DR The Seawise Giant is a double hull tanker. You can remove a hull, make a compartment structure of lightweight materials and storage to approximate the empty load of the tanker correctly. Nuclear power should be enough for the engines and any commodities like loght and water purification. Very roughly 140.000 people can be moved. Might be much lower if you want to pretend a full load, making it 122.500 per trip. Weights would need to be moved back separately as well. [Answer] The primary retrofit issues are "hotel services". If you are keeping 30k people below decks you will need to provide : * Sufficient ventilation for breathing and heat exchange - at least 10 changes / hour. Aircraft run about 20 changes / hour. * Waste disposal / sanitary facilities * Seating / sleeping The machinery for this will occupy significant volume. The ship's existing propulsion plant will be insufficient to power this as it will have been sized to deliver propulsion and auxiliary power for the vessel as specs. BTW load / light does not make much difference to the fraction of propulsion power drawn at sea speed. It's not about mass it's about wetted surface area. Additional generating capacity will be required. At an average of 80kg 30k people mass about 2,400 metric tons. Mass is not your problem. Assume that each person will occupy 4m3. Allow 100% for access. There will need to be intermediate decks fitted in the holds as there will be insufficient tank top area to accommodate your people. Also food for the voyage will need to be supplemented by food for the loading period. How long are you planning on taking to load these folk? If this is a country with an oil industry have you thought of sneaking people out on crew boats? That might be simpler? [Answer] I feel like the answers here assume small hotel rooms for the people. I don't think this operation would look like this: [![capsule hotel](https://i.stack.imgur.com/GTXYA.jpg)](https://i.stack.imgur.com/GTXYA.jpg) I think you can achieve higher density, and more lives saved, by taking this approach: [![afghanistan plane](https://i.stack.imgur.com/AeMsN.jpg)](https://i.stack.imgur.com/AeMsN.jpg) The image is disturbing, but that is what people do [when evacuating from a hostile country](https://www.theguardian.com/world/2021/aug/17/afghanistan-striking-image-appears-to-show-640-people-fleeing-kabul-in-packed-us-military-plane). Sure, that plane trip was less than a day, but to survive for 98 hours, all you need is water and fresh air. Privacy is a luxury. I suggest you put people lying side-to-side, have them exchange water bottles and pee bottles between them. This will not be comfortable. But it will save lives. [![slaveship](https://i.stack.imgur.com/kfJUE.jpg)](https://i.stack.imgur.com/kfJUE.jpg) To allow for walkways and the engine; I take the low end of that capacity, 500 000 cubic metres. The smallest volume that physically fits a person (40 cm wide, 30 cm high, 200 cm long) takes up 2.4 m^3. That means you can have 210 thousand people on that boat. [Answer] ## Make the ship a part of the murder plans This isn't an answer to your exact question, but I wanted to provide an alternative angle which might reduce your challenges. Instead of trying to hide *everything*, you could opt hiding for *one thing*: Contact the goverment (in a secret back alley kind of way ofcourse) and offer them your boat (ofcource for a nice reward (money, power, ...), not asking anything would be weird) and plan with them to make the boat sink with all those filty people in it! They now have a nice way of transporting *all* those people (because why would the goverment care about comfort?) and you dont have to expect inspections, because why would they inspect you, you're on their team! All that paperwork will be handled upstairs. You offer a nice location, which just happens to be passed a nice island to offload those people, where you will make the ship sink! The ship does actually sink with all people on it while the evil goverment is watching, hearing all the screaming! Satisfied they go home. What they didnt know: All passengers got an provided air tank and can just wait a while and be picked up later. ]
[Question] [ [This blog post about binary-star systems](https://medium.com/universe-factory/life-on-tatooine-planets-in-binary-star-systems-4bee211d4dfc) points out that, rather having the stars be close together, they could be far apart and a planet might orbit just one of them. It gives the example of the binary system in Alpha Centauri, where the two stars are 23 astronomical units apart. The post ends: > > A better scenario is one in which a planet orbits just one of the stars. If the two stars are separated by a large distance — say, 100 AU — then life on a planet orbiting just one of the stars can be similar to life on Earth. The right configuration can make things quite comfortable — and still provide some awesome views of the sky at different times. > > > Suppose I do that -- I have an earth-like planet orbiting a G-class star in a binary system. I'll assume for now that the second star is also G-class, but I'm flexible about that. Suppose the planet is in the goldilocks zone of the star it's orbiting and the other is much rather away, 50-100 AU. Some questions from the planetary perspective: * Is the light from the distant star significant? Does it illuminate the planet as much as, say, the earth's moon does at night when full, or is this basically just another bright star in the night sky? (Could it be brighter than the moon, even, making a sort of "second day" during part of the night?) * Are its gravitational effects significant? If so, how do they manifest? Is it seasonal? (If the planet is orbiting one of the two stars, then there will be times when it's between them and times when they're both in the same direction.) * At that distance, does it contribute noticeable heat? * Are there other obvious effects I should be asking about but haven't anticipated? [Answer] OK, so we have two sun-like stars (I'll just write "suns" from now on) at $100\,\rm AU$ distance, and a (probably earth-like) planet at $1\,\rm AU$ distance from one of the suns. I'll call the sun the planet orbits the "near sun" and the other one the "far sun". I'll assume circular orbits throughout. Let's first look at the system of two suns. In orbital mechanics, we have $$\frac{r^3}{(M\_1+M\_2)T^2}=\frac{G}{4\pi^2}$$ where $r$ is the the radius of the orbit, $T$ is the orbit time, $M\_1$ and $M\_2$ are the masses of the bodies, and $G$ is the gravitational constant. By inserting the properties of the earth's orbit (and using the fact that the earth's mass is negligible compared to the sun's mass, we get that $$\frac{G}{4\pi^2} = 1\frac{\mathrm{AU}^3}{M\_{\odot}\mathrm{yr}^2}$$ where $M\_\odot$ is the mass of the sun and $\rm{yr}$ means year. So inserting the parameters of the double-sun, we get $$\frac{(100\,\mathrm{AU})^3}{2M\_\odot T^2}=1\frac{\mathrm{AU}^3}{M\_{\odot}\mathrm{yr}^2}$$ which means $$T = \sqrt{500\,000}\mathrm{yr} \approx 700\rm yr$$ In other words, the suns need about 700 years to go round each other. So a human living on your planet would see the far sun move considerably relative to the fixed stars during his lifetime, but never see it return to its original place. In the following I'll assume that the planet's orbit is in the same plane as the orbits of the suns around each other and going in the same direction, as this (or an approximation of this) is the most probable situation. Now let's look at the gravitational effects of that far sun on the planet. I'll give all accelerations in units of the acceleration the near sun's gravitation causes for the planet (that is, the acceleration the planet would experience if there would be no far sun), which I'll call $a\_0$, and which is $$a\_0 = \frac{GM\_\odot}{1\,\mathrm{AU}^2} = 4\pi^2\,\frac{\mathrm{AU}}{\mathrm{yr}^2}$$ Let's look at the situation where the planet is between the two suns. Then its distance from the far sun is $99\,\rm AU$, and thus the acceleration caused by the far sun is $a\_0/9801 \approx 1.02\cdot 10^{-4} a\_0$, in the direction away from the near sun. To put this in comparison, Jupiter has a mass of about $10^{-3}M\_\odot$ and a minimal distance to the Earth of about $4\,\rm AU$, giving rise of a gravitational acceleration of about $2.5\cdot 10^{-4}a\_0$. That is, the far sun's gravity affects the planet less than Jupiter affects Earth. Then, let's look at the brightness of the far sun. The brightness is usually given by the apparent magnitude. The Sun's apparent magnitude (and thus the apparent magnitude of the near sun) is about $−27$. Now by definition a factor $100$ in brightness corresponds to a difference of $5$ in apparent magnitude, and since the brightness goes down with the square of the distance, the far sun at $100$ times the distance has a brightness of $1/10\,000$ of the brightness of the near sun, therefore the far sun would have an apparent magnitude $10$ higher than that of the near sun, that is, $-17$. The moon has an apparent magnitude of $-13$, so the far sun would be about 40 times as bright as the full moon. This means you might be able to see it even on the day sky, as long as it is not too close to the near sun. Finally let's look at what it would look like. The size (angular diameter) of the Sun, as seen as the Earth, is about half a degree. The far sun is 100 times as far, so the size will be 1/100 as large, or about 20 arc seconds. That's about the same as Jupiter as seen from Earth. So the far sun would basically look like an extremely bright planet. In particular it's still large enough that it doesn't twinkle. [Answer] > > Is the light from the distant star significant? Does it illuminate the planet as much as, say, the earth's moon does at night when full, or is this basically just another bright star in the night sky? (Could it be brighter than the moon, even, making a sort of "second day" during part of the night?) > > > Let's use formulas for [magnitude](http://en.wikipedia.org/wiki/Magnitude_(astronomy)) to answer this. First, note that the Sun has an absolute magnitude of [4.83](http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html). Therefore, both stars will have the same absolute magnitude. The formula for apparent magnitude is $$m=M+5\log\_{10}\left(\frac{d}{10\text{ parsecs}}\right)$$ where $m$ is absolute magnitude, $M$ is apparent magnitude, and $d$ is distance, in parsecs. Given that $d=100\text{ AU}\approx 0.000485\text{ parsecs}$, we find that $m\approx-16.74$. For Earth, the Sun has an apparent magnitude of -26.74, so the second star should be roughly 11 orders of magnitude dimmer than that. Enough for a "second day"? I would say not. > > Are its gravitational effects significant? If so, how do they manifest? Is it seasonal? (If the planet is orbiting one of the two stars, then there will be times when it's between them and times when they're both in the same direction.) > > > This depends on the [eccentricity](http://en.wikipedia.org/wiki/Orbital_eccentricity) of the stars' orbits. In the blog post, I assumed that the orbits were pretty much circular, corresponding to an eccentricity of about 0. This means that the change in distance between the planet and the second star is only about two AU - from 99 AU at the closest approach to 101 AU at the furthest. To calculate the difference in the gravitational forces between the planet and each of the stars, it's easier to simply write the distances in ratios. Using [Newton's law of universal gravitation](http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation), $$F\_i=\frac{GM\_im\_p}{r\_i^2}$$ where $m\_p$ is the mass of the planet, and $F\_i$, $M\_i$ and $r\_i$ are the force on the planet from star $i$, the mass of star $i$, and the distance to star $i$, respectively. Say the planet orbits star 1. At its closest approach to star 2, $$\frac{F\_1}{F\_2}=\frac{M\_1}{M\_2}\frac{r\_2^2}{r\_1^2}=\left(\frac{r\_2}{r\_1}\right)^2=\left(\frac{99}{1}\right)^2=9801$$ In other words, $F\_1\gg F\_2$, and the gravitational effects from star 2 should be negligible. To find the specific perturbations on the orbit of the planet, we would have to solve [the three-body problem](http://en.wikipedia.org/wiki/Three-body_problem), specifically, the [circular restricted three-body problem](http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node120.html), given that the planet is much less massive than both stars. That said . . . I assume you won't be interested in that; it's really quite unimportant. > > At that distance, does it contribute noticeable heat? > > > A version of the formula for for [effective temperature](http://en.wikipedia.org/wiki/Effective_temperature#Surface_temperature_of_a_planet) tells us that, in the absence of the greenhouse effect, the surface temperature of the planet should be roughly $$T=\left(\frac{1-a}{4\sigma}(F\_1+F\_2)\right)^{1/4}$$ where $F\_1$ and $F\_2$ are the fluxes from stars 1 and 2, and $a$ is the planet's albedo. Flux, just like gravity follows the inverse-square law, and so $F\_1/F\_2=9801$. Therefore, $F\_1\gg F\_2$, and we can essentially ignore the second star when calculating the temperature of the planet. If you're looking to explicitly calculate the habitable zone, [I've written some code to do that](https://github.com/HDE226868/Binary-habitability), but I've done some testing, and the habitable zones around each star will be essentially no different from the habitable zone around an identical, solitary star. ]
[Question] [ ## In my world, religion isn't simply true — it's manifestly true. *Generally, prayers are "correct" if they ask for a clearly identifiable and somewhat plausible object, or effect, or event. More detailed rules at the end of the post*. **Most "correct" (see above) prayers get answered** - positively. If you didn't know any better, you'd swear your $DEITY was a Star Trek Computer + Replicator. * \$DEITY, $CUSTOMARY\_PRAYER\_STUFF, Please grant me Tea, Earl Gray, Hot. DONE. Though, maybe I'll pour the tea on your head since you didn't pray for tea in a cup. The $DEITY is... easy to amuse and has a sense of humour of a 5 year old, at times. * \$DEITY, $CUSTOMARY\_PRAYER\_STUFF, Please grant me a tea-making machine that I don't have to refill with tea packets. **NOT** done. Implementation isn't specific enough. * \$DEITY, $CPS, Please grant me and my wife 15 kids. DONE. I'll amuse my divine self at your attempts to scrape together more than 5 consecutive minutes of sleep in the next 20 years. * \$DEITY, $CPS, Please grant me courage DONE. Biochemical balance adjusted. Though, I'm tempted to VTC your prayer as too broad, as you didn't specify how much and for how long. * \$DEITY, $CPS, Please grant me immortality **NOT** Done. Not specific enough and not really plausible. * \$DEITY, $CPS, [IDDQD](http://www.internetslang.com/IDDQD-meaning-definition.asp) **NOT** Done. Nice try, though. * \$DEITY, $CPS, Please give me the 12 gauge auto-loader; the 45 long slide with laser sighting; phase plasma rifle in 40-watt range and the Uzi 9mm. DONE. **Good luck to that dude to cut you off in traffic earlier** * \$DEITY, $CPS, Please kill that a-hole who cut me off. **NOT** done. Too generic. * \$DEITY, $CPS, Please kill that a-hole who cut me off, driving a truck with license plate I-DRIVE3; by blowing up his truck's gas tank with a lightning hit. **DONE**. The level of specificity is good enough. --- **Oooooupsie! Anyone can pray for offensive wishes**. Both to help them do harm on their neighbour, and to do said harm directly. As long as the wish is specific and plausible, it's almost guaranteed to be granted. **So... you have two choices:** 1. Be an angel. Remember Earthling Prophet R. A. Heinlein, with his "An armed society is a polite society. Manners are good when one may have to back up his acts with his life". Read his Holy Book of "The Moon is a Harsh Mistress". And hope you don't inadvertently tick off anyone without meaning to (nearly impossible, if you go ahead and live a real life). 2. Try to wish for defensive prayers. Now, here we run into a bit of an implementation issue. As we saw above, really generic defensive prayers (invulnerability, immortality) won't get granted for lack of specifics and/or plausibility. Generic/conditinal prayers won't work as well ("please make sure nobody pissed off at me today orders a prayer against me" - FAIL. "please make everyone like me today" - FAIL. "please prevent me from getting into any accidents" - FAIL. "please prevent my car from having lightning bolt strike its gas tank" - Granted. The $DEITY is curious if you remembered that one can ALSO pray for a meteor to fall on your head. Or a brick. Or for an RPG to shoot your car with). So... **what can be done to increase one's survival chances in such a society, where if someone wishes you harm, you are pretty much guaranteed to be D.E.D. as soon as they want to**? --- **Extra prayer rules:** * Prayers resulting in mass deaths won't be granted (say, anything killing >10 people total). So, no wishing for nukes or such, as a weapon or as an event. * Prayers asking to change prayer rules, and other such meta prayers, won't be granted. * Prayers that include SQL statements (ANY, ALL, and other such words being a tell-tale) won't be answered. * Prayers that read like a computer program with variables and controls statements might be rejected. "Please kill with a falling brick the first person who prays for my death today" won't work. You gotta name the person explicitly enough. * Accidental prayers won't be answered. "I wish my wife's head fell off", after a much-loved wife threw out your favourite sweater with holes, won't be granted, since $DEITY knows you didn't mean it and would instantly regret it. * One unorthodox way of increasing your prayer's chance of being answered, is to amuse the $DEITY somehow. But that's dicey - their sense of humor is... unpredictable, ranging from subtle irony to far less sophisticated. * Somewhat irrelevantly, prayers may be affected by how well you follow the commandments. BUT... commandments are few, and pretty trivial to follow. NOT your Biblical 10 commandments league. Things like "don't steal" (who needs to when anything you want can be prayed for). "Don't call $DEITY 'dude'". "Don't drive pink animals or pink cars". * Information request prayers may or may not be granted. To be granted, they have to be specific and plausible and fit other rules (e.g., wishing for a piece of paper with a recipe of pot pie in a restaurant X is granted. Wishing for the recipe itself won't work since "a recipe" isn't an object or event, just information. Wishing for the name of a person who wants to kill you won't work. Wishing for the name of the person who did something specific might work, but is dangerously close to "No SQL queries" prohibition). [Answer] Like any usable weapon, your kin and allies and eventually a society will address misuses. The brother of the deceased can *pray* for a report on what happened and why and by whom. This might get worked out well enough over time that a bureau will get a list of all prayers made, just like you can look through Google searches, but including particulars. Payback will be handled by the same experts, who have refined their punishment “spells”/scripts over generations. Your examples imply a simple last-command-effects with no priorities. So praying to not get caught is pointless, as the police detective will pray that you *do*, and the dedicated force of constables/chant-singing-monks will instigate a denial-of-service campaign against your further use of prayer. [Answer] I would guess, that most jerks would be eliminated early in life and so the survivors would tend to be (more) polite and considerate of others, karma and golden rule to the nth degree! Also they wouldn't really need to even invent weapons, if I can say "Please kill Grog with rock on head", why do I need an MP5? If I can say I want a sirloin stake for diner, I don't need to hunt or gather or really do anything! All I'd need to do is try to avoid practical jokers who might ask for me to wear a pink leotard and dance swan lake. Now if this was something where the deity just showed up yesterday and started granting these wishes, life would be very interesting for a few years, starting with the death of almost every single famous person still alive, including every single politician on the planet. My guess is most of them would be dead before we even realized that our wishes/prayers really were coming true. Personally I would stop posting anything on the internet the moment I figured it out, but it might already be too late! So my best attempt, would be "Please let me know with a bell sound when harm is wished upon me" and "I wish to find a piece of paper detailing any harm wished upon me 15 minutes early". These might give me enough time (if granted) to fix and counter the harm being sent. [Answer] I think people would soon get into the habit of praying repeatedly all through the day. Example *Please ensure that the bus I am currently boarding reaches my desired bus-stop on schedule, with me in it and in good health.* Then when you get near the bus-stop: *Please ensure that I am able to get off the bus without doing damage to myself or others.* etc. The fact that I personally may have left some loopholes in my examples above is because I am a stranger in this world. This would be taken care of in the actual world because natural selection would eliminate people who couldn't formulate good prayers. [Answer] Become a hermit. Personally I'd wish for a house on the moon, and if that was outside the scope of prayers I'd simplify by prayers, piece by piece, until I had everything required to get to the moon and build a house/infrastructure to survive. Then I'd wish for the ability to move the moon, and if that was too much I'd again simplify my prayers until they reached the point where they were accepted, and build some giant engines on the moon. Then I'd fly off on the moon, into the wilderness of space, and leave Earth behind, living off wishes. Sure it may be a lonely existence, but at least I won't be a slave to the whims of others prayers. Really I'd just need to make sure nobody knew it was me who stole the moon, as I suspect wishing for 'the moon to reappear' would be outside the scope of a prayer, so I'd be free! Once I'm exploring, I'd just mess about with wishes I guess, use them to stock up on food, make repairs, etc, maybe get the latest TV shows etc. [Answer] Insight: If you substitute the words "pray for" with "do something about", then many of the rules in the real world apply to yours. So, in the real world you stop people from stealing your stuff by 1. living in a society where people teach their kids that stealing is wrong and 2. having heavy doors with big locks. In your world, you have people 1. pray for their kids, that they'll treat people properly, and 2. you have them pray for decent body armour. [Answer] I feel like the real trick here is anonymity. Since "that a-hole who cut me off" isn't specific enough, and they need to identify the user with a license plate number, your main character here needs to trick the people who want to hurt him/her by being utterly unidentifiable. This would require a particularly crafty character. If he tries to remove the license plate from his truck, someone might specify "The truck with no license plate", so he would have to pre-meditate, perhaps place a license plate underneath the truck which would identify to $DEITY sufficiently and cause any unwell-wisher to mess up their prayer. The character can either hide their identity through magical or mundane means -- perhaps they have a spell that makes them look different, perhaps they're wearing a wig. Either way, most people probably aren't trained to call out "That guy who looks like he has red hair". [Answer] So an expanded [Death Note](https://en.wikipedia.org/wiki/Death_Note), then? Well, I suspect many would retreat into seclusion, and as others got closer they would pray, *"Please make this person my servant, obedient to me in everything including praying to you."* Eventually you'd end up with tribes of controlled people, perhaps waging wars over resources. [Answer] We have to consider the history of this world. Let us suppose there was a time when the primitive inhabitants weren't aware of there being a god and simply didn't pray. Maybe they didn't even have language at that point. As soon as they discovered how to speak and how to pray they would start to ask for things. At first these would be simple things because they are a primitive people. They might ask to have a successful hunt for example. Any member of this race who didn't get the hang of the system would simply be eliminated by natural selection. As time went on, the survivors would learn how to handle things. They would keep their children under careful protection until they were able to pray properly. Maybe they would have to be gagged so as not to speak childish prayers. As the society became more sophisticated, people would start to realise there are rules to these prayers. Scientist-priests would experiment by trying out different forms of prayer to see what effect they had. They would become experts in manipulating the system. **My answer** Get the best education you can. This world would definitely have the equivalent of a University of Prayer. One of the most important classes would be Formal Logic and its relationship to Prayer Logic. *Answer edited in accordance with justified criticism.* ]
[Question] [ I'm talking about this sort of liquid sand: <https://www.youtube.com/watch?v=My4RA5I0FKs> "Desert-as-sea-analog" is present in many media, but often they lean heavily into fantasy, and it seems not many of them have explained how it works. I'm guessing it's a regular desert with some sort of geyser-like system below it that produces steam, but instead of shooting all at once, it creates steam at regular pace over wide area, which produces liquid sand effect as seen in the video above. [Answer] **In reality? No. But believably? I believe so!** You can't use fluid, this would coat and weight the sand and you'd quickly have mud, which is almost as solid as the dry sand in the first place. It must be a dry gas, fairly evenly distributed along the "sea floor." As Gimelist mentions, volcanic gasses are the most likely candidate because the volcanic heat is melting things (dry things) and a component of that process is gas. Offhand, I can't think of any other way to create gas in sufficient quantities that this would work. *Note, from the point of view of "realism," you have a problem with a reasonably consistent flow of even volcanic gas. Once something's melted, it requires more heat to get more gas from the same cubic meter of magma. In other words, you need to keep melting new material to get more gas. It's very unlikely that the quantities you need can be achieved. But that shouldn't stop us!* Next, we need a distribution system. You'll notice all that lovely copper pipe in the bottom of the hot tub in your video. Geophysics aren't usually so convenient. But, what if our planet once had a massive coral seabed? [Some dead coral is porous](https://pdfs.semanticscholar.org/dd02/245424bc8f9e6b37cb6506b163427684e6cc.pdf), so let's have, say, a large, shallow, sea that is chock full of coral! Then something happened (this "something" will be important in a moment) to drain the sea, and the coral died, and the winds came, and then the sand, and the existence of the coral has become lost to time. So, we have a source of gas, a distribution system (the coral) and the sand on top. Now we need to get the gas from the volcanic source to the coral in a way that distributes the gas reasonably evenly but *doesn't* melt, crack, or destroy the coral. Let's talk about that "something" we just mentioned. Geothermal consequences make their way to the surface in many different ways. Usually, they're narrow ways — like volcanoes. We need that gas to cover a huge area with enough pressure to seep through the coral and bubble up through the sand. I give you... *A [caldera](https://en.wikipedia.org/wiki/Caldera).* And not just any caldera, but the [Yellowstone Caldera](https://en.wikipedia.org/wiki/Yellowstone_Caldera). In other words, reasonable proof that a large tract of land could have, not to terribly far beneath the surface, active magma. We don't want a single large release point of gas (volcano), we want a massive area with — if there was water — mud pots and geysers and hot springs and all kinds of ways for the gas and heat to get to the surface. Now, this isn't to say that the Yellowstone Caldera is one giant mud pot. But it's a proof-of-concept that a large area with lots of cracks and fissures that don't lead to coral-melting heat can exist. Cracks and fissures that can release gas. So, underground magma is creating gas, gas percolates up through a large, shallow caldera, encounters the porous coral sea, which distributes it along the sandy sea bed, creating the sandy sea you're looking for! What are our limitations? * Dry! You can't have water. That means no aquifer. I'm not convinced that's possible (water has a habit of getting everywhere), but maybe our planet's a bit like *Arrakis,* where the water has been conveniently contained by the Little Maker vector of the sandworms. Maybe the "ocean" is surrounded by the massive crater of the caldera, guaranteeing no rain falls on the sea, whatever, you *can't have fluids anywhere near this sea* or it won't work. * Shallow! While the video shows a couple of feet of sand in the hot tub, it isn't showing how much air is being pushed into the system. I suspect *it's a horking lot of air.* The deeper your ocean, the more gas is required, the higher the pressure under the coral, the more likely you'll break up the coral and ruin the effect. So your boats will all have shallow keels, I suspect the "ocean" would need to be no more than 2-3 meters deep. * Small! You can't have planetary oceans, like the Atlantic or the Pacific here on Earth. That's simply too much area to explain with a caldera (or any other means of generating/distributing the gas). I think you could believably argue something the size of the Mediterranean sea is as big as you could believably make it (without simply ignoring believablity, which is how everyone in the past did it). * HOT! Not hot enough to burn the boats maybe, but definitely hot enough to cook the proverbial egg. Remember, *volcanic gasses!* No water nearby and you'll be sweating like a stuck pig. Better bring plenty of water with you! This will also affect the design of your boats, which won't want to have sealed areas below decks. Think "oven." * Geologically stable! Which is a somewhat difficult sell considering we're depending on a caldera. But, if you permit volcanic actions or earthquakes, you'll break up the coral and the whole thing goes to pot. Note that the coral will never distribute the gas evenly. This means you'll have a believable argument for currents, areas where you can move quickly and areas you must slog through, even islands! No trees, but the lizards definitely want to make the acquaintance of new water sources! Finally, you can have a ton of fun with the flora and fauna of this ocean (which might be used to contribute to the dryness requirement — if they pick up every drop of water fast enough!). I'm thinking it! I know you are too! [*Land shark!*](https://www.nbc.com/saturday-night-live/video/landshark/2832305) *May the mighty [Sarlacc](https://starwars.fandom.com/wiki/Sarlacc) never find your ship!* [Answer] Perhaps a vast colony of lithotrophic organisms lives deep beneath the sand? Long ago, the region was a rocky plain. Then, a species of lithotrophs was introduced, and they began to consume the very rock. The resulting by-products? Sand and oxygen rich gas. Over millions of years, the lithotroph colony has excavated deep into the crust, leaving above it a vast desert. Their gaseous excretions acting to liquify the sand above. [Answer] **Boil / condensation.** Imagine a world where the atmosphere was mostly medium chain alkanes - like gasoline. At night the atmosphere largely condenses into liquid and trickles down thru the sandy surface to deep pools. In the day, the heat of the sun causes the alkanes to volatilize. They bubble forth from under the sand, causing the effect you want. This offers a method to regenerate the bubbling sand fields daily, indefinitely. [Answer] No Not on an earthlike planet. the nature of sand means once it gets thick it becomes immobile, worse at only a few meters it begins to reconnect into a solid thanks to pressure welding, if you somehow forced it to move it would be so abrasive it would grind itself into silt or clay in weeks. There are two ways to help, ideally you want to combine them, but even then it is really iffy. 1. it is not sand but a sand like organism, that opens up some options at least although not great ones. preferably something that grows a near perfect spherical super durable shell. 2. Use a lower gravity, sand compression will not be as big of an issue, but you will still have the abrasion problem. ]
[Question] [ In my Fantasy world there exists a crevice. Plants and animals made of glittering, iridescent crystalline structures in abundance. The crevice can contain any arbitrary materials that might make the existence of such creatures, though it must also be livable for humans and exist alongside the rest of the 'normal' world. The 'plants' look just like crystals in our world, but they grow and mature over time, eventually producing tiny crystal seeds to reproduce. e.g. A crystal like this: ![A crystal like this](https://i.stack.imgur.com/P7TGO.jpg) The 'animals' exist as both herbivores and carnivores. They of course subsist by preying on the crystal plants and herbivores, respectively. e.g. Something along these lines, though ideally more iridescent and translucent: ![Something along these lines, though ideally more iridescent and translucent.](https://i.stack.imgur.com/VMKSc.jpg) The creatures do not necessarily need to be made of literal crystals. The desired properties are that they look translucent and iridescent with square-patterned protrusions. They should be hard and smooth to the touch. Is that kind of thing realistic? Are there any examples of real-world living creatures? This question is for a fantasy setting which has magic, but if possible I'd prefer answers that used as little magic as possible. **Are creatures that appear to be comprised of translucent, iridescent crystals possible?** [Answer] Carbon based life is the fact on Earth because C can bond with 4 other elements - but there is another common element which can also do this: **Silicon**. --- For the crystal requirement: Silicon is a [crystalline structure](https://en.wikipedia.org/wiki/Silicon), is the 7th most abundant element on Earth, and includes many silicate units which would match your monster needs. --- For the (additional) science, last year (2017) scientist Charles Choi successfully bonded [silicon into carbon based molecules](https://www.astrobio.net/news-exclusive/astrobiology-top-10-possibility-silicon-based-life-grows/) showing that an evolution of silicon based life is *possible*. The full article is available through a paywall but to quote the abstract1: > > Enzymes that catalyze carbon–silicon bond formation are unknown in nature, despite the natural abundance of both elements. [...] Using directed evolution, we enhanced the catalytic function of cytochrome c from Rhodothermus marinus to achieve more than 15-fold higher turnover than state-of-the-art synthetic catalysts. This carbon–silicon bond-forming biocatalyst offers an environmentally friendly and highly efficient route to producing *enantiopure organosilicon molecules*. > > > This could be used in a story on another planet to show how silicon based life forms came to be instead of carbon or to show how directed scientific evolution lead to the development of silicon based life forms on Earth which after "*horrible world altering event #178*" caused them to increase in variety and strength until they became one of the dominate spieces on Earth (i.e. your plants and monsters). 1 S. B. Jennifer Kan, Russell D. Lewis, Kai Chen, Frances H. Arnold, Science 25 Nov 2016: Vol. 354, Issue 6315, pp. 1048-1051 [DOI: 10.1126/science.aah6219](http://science.sciencemag.org/content/354/6315/1048) [Answer] A combination of biology will do the trick here. You can observe any of the following in nature: * Keratin - Cutaneous horns. * Bone - Carapaces, other types of protrusions, and horns. * Ivory - Tusks and teeth. * Enamel - Teeth. You can also observe iridescence and translucence in nature such as the morpho butterfly and chameleon. Their external cells are crystalline and are structured to have beautiful spectrum of colours for visual effect. The protrusion patterns on your animals are down to evolution, predatory/prey relationships, and behavioural patterns. [![enter image description here](https://i.stack.imgur.com/DeGoP.png)](https://i.stack.imgur.com/DeGoP.png) [Answer] Traditional Earth Biology is based on proteins floating in water, some of it organized into cells. Large crystalline structures in animals are generally laid down by living cells, but not alive themselves Some examples : Coral is laid down by a variety of cellular organisms which lay down on top of existing surfaces, but the organisms are not the crystalline part itself. Bone is created by most animals, extruded from cells which then harden, and then the hard crystal part is not really alive anymore. Bones have many hollow spaces, which contain living cells, which maintain the crystal structure as well as other health aspects of the whole organism. Scales, horns, nails, and hair are generally layered protein, not big transparent single-substance crystals. But you could scale it up if there was an evolutionary advantage. Large amounts of otherwise-useless weight don't help a creature that needs to move. You would need to make a reason for it - perhaps it's intelligent, and the crystal holds a thinking matrix of light. That's a difficult thing to bootstrap into a biosphere. And generally brains get hidden inside animals for protection. [Answer] There are TONS of good examples in nature that could be used as a basis for this concept, and combined with each other. The most difficult aspect is "translucent" but even that isn't too hard to come up with. With some minor "magic"(or another variation of handwavium you prefer), it's not much of a stretch to get to what you described. First, for **plants**: Diphylleia, or skeleton flower, is a white flower whose petals turn transparent when wet. Lunaria annua is a plant that has translucent seed pods And Haworthia plants come in many varieties, some of which are translucent, and most of which are in a very crystalline arrangement. Bio-luminescent fungus might be an inspiration for "glittering" plants or plantlike things. (keep in mind that some Lichen are fungus+plants in a symbiotic relationship, if you add bio-luminescence to that, and scale it up, you have sprawling and glittering plants and wall surfaces.) Now, **animals**: For "glittering", the first thing that comes to my mind is fireflies, but then there are a huge variety of sea creatures that are also bio-luminescent. On land, most bio-luminescence seems to be bugs and bug larva, but there are bio-luminescent land crabs as well, and earthworms, and more. As a bonus, most bugs crabs and snails also have hard shells or exoskeletons, adding to the appearance of rigid crystalline structure. For "iridescent", many snakes have literally iridescent scales, which are already crystalline both in shape and texture. Also, some snakes (and many other reptiles) have their scales "ruffled up" which would add to the crystalline appearance, look up Atheris hispida as a good example of this ruffled up appearance. For "translucent" animals, this is by far the hardest, but there is a precendent for it, even for animals that have a hard(-ish) structure. There are glass frogs, but frogs in general aren't known for having a crystalline external structure. Fish scales are decidedly more crystalline in appearance already, and there are glass fish as well. Crustaceans, such as crabs and lobsters have a hard and stiff surface, and there are glass shrimp (mini-lobster-like appearance, but clear) that have a similar hard shell, though decidedly softer than the shells of most other crustaceans. One final bit of inspiration that came to my mind for this question is scorpions in UV light. In summary, real life ... life ... has plenty to choose from if you're looking for something to base fantasy glowing+iridescent+translucent+hard shelled plants and animals. Take the parts of real life that are the best for your story needs, mix them in ways that real life hasn't done, and you should be able to come up with something real-ish, but not real enough to be really real. (really) [Answer] I wonder how mechanistically you could build this ecosystem: because crystals are weird. (Apologies to any actual chemist, my chemistry knowledge is pretty limited) In high-school science, many students grow crystals, such as copper sulphate crystals. They do so by taking a saturated solution and letting it evaporate, which forms a layer of crystals on the wall of the beaker. Then they take a single crystal and suspend it in the solution. It provides a nucleation point for which a single crystal can continue to grow. Thus, if we can have an atmosphere that is saturated with some chemical, we could potentially have the primary producers of our ecosystem without needing any actual biology or life: the crystals gradually grow as they strip chemicals from the atmosphere. The harder part is continuing the ecosystem in this way. Maybe we could have rolling crystals that roll towards the densest concentration of some gas (they absorb it on the side closest to the gas vent making that side heavier). Maybe these "rollers" eat the naturally growing crystals, and they grow bigger and bigger until they collapse under their own weight. And when they collapse, perhaps the two halves can re-form into a ball and keep on slowly rolling? Maybe you could use piezoelectricity to make some sort of jumping thing whenever there is a thunderstorm. Similarly, some crystals are photosensitive, so you could have some other oddities there (some odd structure that takes one step per day/night cycle?) However, this is not biology, and is not an ecosystem. There is no complex conveyance of design (no DNA) and nothing beyond strange physical effects. Such a planet would be inhospitable in the extreme, and very disturbing to any explorers. ]
[Question] [ Imagine a world two or three hundred years in the future, starting from now, in which some corporations (or groups of them) become independent states with sovereign territories. I’m aware this is very unlikely to happen in the today's world, that’s why I’m giving three hundred years for political, sociological and legal changes to develop. Some conditions are: * Cession must occur from one of today’s most developed countries with strong democratic tradition, like the US or somewhere in Europe, which also houses the most powerful corporations and most of the wealth in today’s (and future) world. * The country from which the cession has occurred is relatively “stable”. There are no civil wars or revolutions; there are political scuffles and corruption, but no government has been deposed in centuries. Everything occurs through legal changes or democratic voting (again, like in today’s US or Europe). * There are social classes: A majority of underpaid manual workers, a middle class of educated and highly-skilled workers, and an exceedingly rich minority in charge of the mentioned corporations and with significant political power. * The most important: Society has changed, but the world has become neither a dystopia nor a utopia. The purpose of these writing is to explore the political and sociological changes the world must go through to make that kind of things possible and I am not trying to explore the morality and beneficial or negative consequences of such changes. My reasoning goes like this: Corporations progressively take control over social matters in their headquarters and small surrounding territories, providing employment, security, education, health, roads, transportation and a long etc., like a [company or college town](https://en.wikipedia.org/wiki/Company_town) with significant financial muscle. With time, corporations stop lobbing and make their own candidates run for office, which then get elected. Corporation-appointed politicians and public officials acquiesce to reduce corporative taxes if the corporations do a good job in running their “territories”, progressively taking over the responsibilities of financially-strained governments. These responsibilities can start as things like the mentioned social services, but progressively span to more complex affairs, like issuing passports, managing their own international relations and establishing a judiciary. And the cycle continues, the corporations progressively cut bonds with its parent country until they become independent through a popular referendum or signing a treaty. Also, in the process, the corporations develops its own complex-inner government, probably a mix between management and democracy. Am I missing any tipping point here? What would you add to this theory to make it more plausible? Starting from the current state of affairs in the world, how could a corporation become a country in two or three centuries? [Answer] It looks like you're on the right track. A major tipping point may be the successful defeat of anti-trust legislation. For a corporation to become a viable state they would need monopolies and diverse portfolios. More or less they would probably want/need to control all commerce in their area. This may have an end result of a sort of authoritarian regime where all property is owned by the state/corporation. Much like in the company towns you mentioned, the state/corporation would be your employer, landlord, utilities provider, grocer, healthcare provider, etc... Another tipping point, something we're already seeing in some sectors in the US, is privatization of services formerly provided​ by the government. We already have privatized prisons, schools, hospitals, and security/military forces. If the trend continues and these private companies consolidate... Well that's most of the leg work already done. [Answer] ### Consent The most important thing that would be needed would be the consent of the nation that gives up its territory. Next would be the consent of the governed. How do they keep people in the corporate territory and not leaving for the rest of the country? In the long term perhaps the corporations could restrict freedom of movement, but in the beginning they'd need consent. They would have to be better in some way than the governments that they replaced, or people would just leave. What could a corporation offer that a country cannot? ### Corporate towns There is historical precedent for corporations running territory. It was quite common in mining towns. The corporation would provide housing, food, etc. The corporation would manage transport, bringing in supplies and taking out mined materials. Corporations would have to start doing that again. However, the easiest way to get there is not to carve out territory from an existing nation, but to find new territory. There's not a lot of room on the Earth. Perhaps an artificial island in the middle of an ocean. But more likely would be a space habitat. We already have corporations trying to go to space. And those almost have to operate as corporate towns, as who else is going to pay the massive costs of transport to them? This would begin in space. The first corporations would be in space. They might even be based on non-profits. Once the system works in space, then they would migrate it back to the Earth. [Answer] Corporations would like to get all the profit without none of the expenses, so they tend to shift any burdens - such as assurances or healthcare - to the state, if allowed. I suppose a path could be in the trend of ever-smaller government. With lower and lower corporate taxes and less government spending the government finds itself in a situation were: * Nearly 40% of the population pays no taxes, 'cause they're too poor. * 10% of the population pays not taxes, 'cause they're too rich - and move their money elsewhere. As a result, a increasingly overwhelming share of the taxes falls upon the middle-class, quickly centrifuging it to the extremes. With 65% of the population below the poverty line and 40% of the wealth of the nation in hands of individuals and corporations who also pay (nearly) no taxes at all, the government fails to provide resources to the population, such as education or infraestructure. As a result, companies start to offer these services to attract workers, because they are resorting to emigration or crime. Increasingly, companies find themselves (unwillingly) in the position of becoming states: they have to provide housing, education and healthcare plans to atract workers, police and firefighter to fight against crime and vandalism (and accidents). The government doesn't like the corporations taking its place, but without income it cannot compete. Lack of funding means their military start defecting and becoming private armies under some corporation's payroll. By this moments, the old state is dead, and some newer corporation-states are born. Even if nobody wanted to. [Answer] > > Starting from the current state of affairs in the world > > > , this is extremely unlikely. The major impetus behind the formation of any state is **mutual defense**. Having a lot of money doesn't mean anything if you cannot prevent some other guy taking it from you. US defense spending is ~600 billion USD yearly. Apple's most recent net income (before paying shareholders, etc) is ~45 billion USD. The US military recruits from a population of 320M; how many able bodied people will live in the Apple Republic? How do they maintain deterrence against WMDs? So , you need at least a combination of the following to become true: * **Warfare is conducted largely by AI** (No need for a large population) * **Your corporations become at least 5-times richer than the richest corporations of our era** (Corporations can afford standing militaries) * **The world becomes a much more peaceful place**. * **Either WMDs are somehow eliminated, or the world is fine with extreme proliferation of them** (Apple has its own nuclear arsenal, etc). 2 and 3 may be contradictory. If income inequality continues to rise, it is extremely unlikely that violence would decline. ## The second issue that these tropes always ignore is the granularity of the corporate world. Look at a list of corporations by revenue. You will notice two things: 1. The list changes every quarter 2. There is very little difference between any two corporations listed one after the other, in term of revenue. For example, in the [most current list](https://en.wikipedia.org/wiki/List_of_largest_companies_by_revenue) #43 and #44 have ~107B USD in revenue. So, how thinly are we going to slice the ham? How many independent corporation territories are we looking at? Where do you draw the line in terms of revenue? How about the very next corporation on the list? Secondly, although the major corporations are separate entities in terms of *operations*, the ownership is very much overlapping. Except for Chinese state owned "corporations" and a few family owned ones, great majority of these corporations are publicly traded, so who owns the corporation literally changes by the minute. Also, it is not uncommon for wealthy individuals and investment funds to hold major positions on the boards of several corporations. If I am sitting on the board of Apple, Shell, and McKesson, do I become a citizen of Apple Rebublic, or Shell rebublic, or McKesson republic? Therefore, you need a combination of the following, also: * **Major mergers result in mega conglomerates in a scale unheard of before**. (Historically, over-expanded corporations have not been very profitable. Also, you would need to defeat antitrust legislation somehow.) * **Relatively small number of individuals somehow gain control of these conglomerates** (seems very unlikely starting from today's world). > > Corporations progressively take control over social matters in their headquartes and small surrounding territories, providing employment, security, education, health, roads, transportation and a long etc > > > How this could be profitable for a corporation is hard to imagine. A corporate HQ is just an office building. Apple does not design, manufacture, and ship all its products from one HQ. It owns assets around the world. Also, corporate HQs are already in cities with very decent transportation, healthcare, and education. So, you also need the following, which seems contradictory to your second requirement ("stable"). * **The state and local governments become so dysfunctional that the country's infrastructure is *actually* crumbling. Major centers of learning (Harvard, Stanford, etc) somehow collapse.** (Only then, it may perhaps be profitable for the corporations to finance schools, roads, etc). > > like issuing passports, managing their own international relations and stablishing a judiciary. > > > Running the judiciary inside their micro-state is of little use to the corporation. What judiciary will they turn to for conflicts with *other* corporations? What do nation-states do when they have conflict? There is no court with enforceable jurisdiction over all nation states. They either resort to long diplomatic process or duke it out on the battlefield. Not very profitable... So you also need: * **The definition of a corporation changes from a *for profit entity* to something else.** (Perhaps, instead of sovereignty, the corporations make sponsorship agreements with existing nation-states, the United States of Apple, The United Kingdom of Shell, England, and Northern Ireland, etc) [Answer] I immediately though of small islands in the ocean. The corporation could buy one or even build one. Depending on the exact situation, there may be the legal framework for that corporation to actually fully own the island. This seems to me to be the most cost-effective pathway. Another path may be to effectively buy the government of a small island nation. In fact this may or may not be limited to a small island, but any government willing to sell itself. There are likely quite a few sovereign nations sufficiently susceptible to such a purchase, given a large enough price offering. Yet another way could be exploration of a less charter region. For example, if a corporation establishes a research lab in Antarctica, at the bottom of the ocean, on the moon, or on Mars, that could eventually progress to where the corporation is effectively in charge of land and operating as a sovereign entity. Another suggestion is that the corporation may be able to outright buy some largely unused parcels of land up north in either Canada or Russia, or in the middle of the desert. Finally, lots of indigenous societies have treaties that effectively make them sovereigns over portions of land (reserves). They may sell some of these rights to corporations, given a high enough price. [Answer] # Smart cities A conglomerate company, like google, could buy up large swathes of otherwise useless land on which to build new examples of what their tech could bring to a city in the interest of creating new cities rather than working fixes into old buildings. These could start off as examples of what the company can do, a city with automatic waste disposal from each house, WiFi across the whole city, new methods of travel, houses with integrated smart tech...the list goes on but it would be the city version of the internet of things. Now either you take this further, the city grows, initially as a place for its workers and eventually other businesses move in too. Google, or whoever, own the city. Maybe emergency services get a boost too, robotic police, fire service, surveillance everywhere to identify everyone. # Building for countries So, a massive success, Google City becomes one of the world's most popular cities and everyone wants a piece. So now they start building for countries but the contracts state that, unless the cost has been fully paid off then the company owns the city (giving them a monopoly as the sole electricity, internet, waste, water and transport services provider). The cities will be expensive and the company won't be rushing the countries to pay this off as they get a healthy income from all the people living there. The company then ends up owning more cities and, to some extent, the access to population (voters) in those cities. It won't be long before such a company's influence becomes indistinguishable from ownership of a sovereign state. This is actually an idea I've been considering for a while, a divide growing between those living in the smart cities and those not. The 'Smarts' (or 'Googles', my story did have a sense of kinship to the company) feeling it is the way forward. They then side with the company and when a member of its board puts themselves forward to sit as the MP for that city the vast majority agree that 'Smarts' should have a 'Smart' to represent them...and so the slippery slope goes. [Answer] ## There has to be money in it. For a corporation to invest in government ownership, there must be profit. Otherwise, the shareholders won't go for it. And at the end of the day, profit is all any corporation technically cares about. ## There has to be short-term (and long) stability in it. Any plan that increases instability also increases the risk of losing money. Corporations who increase instability must do so in areas that aren't central to their HQ or operations. Anyone traded on the NY Stock Exchange, for example, is going to be *real careful* to not disrupt the NYSE. Because that's where a significant portion of their value lives and dies. ## There have to be tools. Taking over a country via military force is a bit too overt. If Apple or the Sinister Eli Lilly or whomever tried to build an army and invade Canada, It would end harshly. Every nation would send troops to defend Canada. And those can build bigger armies faster, since they can operate at a loss. So instead, your corporation must use subterfuge and non-lethal tactics. Armies are the tools of nations, not corporations. # Look at what they're doing now... Corporations are exerting heavy influence on global events daily. Lobbyists help congress [write laws](https://en.wikipedia.org/wiki/American_Legislative_Exchange_Council) in the US. They work with nations to formulate [trade partnerships](https://en.wikipedia.org/wiki/Trans-Pacific_Partnership#Secrecy_of_negotiations) -- in secret, so you won't know what's in the agreement until it is already signed. They work to build up laws that make it [harder to fight](https://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Act) their more subtle technologies and tactics. ## ...then ramp it up. Take the foundation stones of that, and build up. It isn't too much to imagine they find a Third World country where the politicians are corruptible, and corrupt them. Buy their way into power somewhere quiet that no one (on a global scale) pays attention to. Once in power, they slowly expand their base, subverting that nation's branches -- the judicial, the legislative, and the executive. Sure, the military is small; they can't take on the US or Russia. But it's big enough to quash any internal complaints. Then they shift their HQ to this nation, because it's cheap. The country literally gives them land, exceptions to environmental laws, and whatever else they need. Then, slowly, manufacturing shifts to this nation. With no oversight, they can keep eroding those costly environmental laws, labor / safety laws, etc. While the subversion is happening, their governmental mouthpieces silence the UN by improving stability, ending civil wars or genocides already in progress, etc. They clean up the place, which makes them look like good guys. Heck, the US, UN, etc. might even supply weapons to make the take-over happen faster. [They've done similar things before](https://en.wikipedia.org/wiki/United_States_and_state-sponsored_terrorism). Sure, people would notice. They'd make noise about it. But by the time everyone realized it wasn't just a conspiracy theory, it'd be too late. [Answer] This has already happened at least once in our history. The [East India Company](https://en.wikipedia.org/wiki/East_India_Company) was formed in 1600 to trade with India and China, but from the 1750s onwards it came to [directly rule large areas of the Indian subcontinent](https://en.wikipedia.org/wiki/Company_rule_in_India) with a private army and the administrative functions of a sovereign state, a situation that lasted for about 100 years. A similar situation could arise in the future if a corporate entity was sufficiently motivated and used similar tactics: * Establishing trade agreements and economic ties and then manipulating them to acquire political leverage and power, eventually subverting the incumbent sovereign authorities and assuming their functions. * Direct military action - a well funded trans-national corporate entity could field a private army capable of overwhelming the military of many smaller or less militarily capable nation states. Given the conditions you've defined, direct military action against "one of today’s most developed countries" is unlikely to be economically viable or feasible for a corporate entity. However it would be possible for a corporation to bring about an economic and political situation (through control of the media and politicians) where a subset of one of those countries decides to cede (e.g. Scotland from the UK, Texas from the United States) and become an "independent" political entity. If this succeeds then the corporate entity could then set about subverting the newly formed, smaller state (e.g. by destabilising the economy, fomenting political unrest) and then present themselves as the solution to these problems, as the only entity capable of bringing stability and prosperity. The desperate population could then be persuaded to vote for a corporate takeover of the state to "rescue" the country. [Answer] Many of the historical examples have to do with colonialism: Dutch East Indian Company, Hawaii, Africa, etc. In the future, this will happen *in space*. It will be only natural for an asteroid mining camp to be an “company town”. What we need first is to *maintain* the company hold as a camp grows into a colony and a larger settlement. Now, I’ve seen estimates as to the **truely staggering** wealth involved: one well-chosen asteroid will contains *trillions of dollars* in precious metals, *trillions of dollars* in rare earth elements, not even counting the iron. This kind of money makes people go crazy. This much inflow of material will destabilize entire economies. People wanting to “get this done” can subsume the previous government to then get the permission and infrastructure they wanted on the Earth side. So the Asteriod Company can, for example, approach a country like England and say “having trouble with treaties and trade because you want China’s cheap steel? *never mind them*, we can provide all you need.” They can muscle in on the world stage simply by outclassing everyone else in terms of sheer resources. As for fighting the Earth nations, we’ve gone over before how inherently dangerous space industry is due to the energy scale. Every ship is a weapon of mass destruction. They plan to *deliver* tons of Iron, gold, etc. to the ground as part of their core businesses, so naturally they will have rocks in a staging area ready to deorbit. This trivially becomes a city-killing weapon. They have the “high ground” and the ability to withdraw out of range of Earth-bound nation’s forces. The Asteroid Company will be the largest superpower. They will take over other governments to get what they want. [Answer] We have several small countries, right now, that are corrupt enough so governments can pay zero taxes (for an up-front 'fee'), or openly sells a 'flag' for their ocean vessels that incurs no regulations, or openly sells one of their allocated rights to launch a satellite, or lets them register as a corporation with zero corporate oversight. Many will outright sell citizenship. Some of these are not democracies but monarchies or dictatorships. They sell these products of their sovereign nation because they are relatively poor, say with wealth in the low millions, and the payday is significant for them. The idea for a very rich corporation would be to just buy out one of these dictators or kings and install themselves as the control of an already sovereign nation. And I mean buy them OUT, say a billion dollars for all the appropriate decrees and signings to make the corporation the ruler and the guy they are replacing retires to Paris or wherever else they like. Then the corporation can install whatever they want in terms of government employees, ambassadors, immigration policy, laws and so on. They can rename their country to their corporate name. They can transfer the wealth and property of their corporation to that of the country they bought. The whole meaning of a "sovereign" country means it makes its own laws, just like North Korea does. All the way to executions, murder, imprisonment, labor slavery, sex slavery and so on. ]
[Question] [ I am creating a fictional fantasy (Medieval-ish era) world. The area covered by my map is fairly large, and contains an ocean, mountains, plains, lakes, forests, swamps, etc. It's pretty much all there (save for desert and tundra). In my world, races are largely limited to one area. So for example dwarves live almost exclusively on the slopes of mountains. Elves live in the forests and plains. Certain tribes live exclusively in the plains, while others live exclusively in the forests. Others live through an entire mountain range. Here's my question: **Who has which natural resources?** I need certain groups to depend on others for trade reasons, but I'm having difficulty figuring out what one group would have based on their location that the other wouldn't. So to put it simply: **What natural resources do certain biomes (including mountainous areas) have that others do not?** If I have a list in front of me, I should be able to establish who's trading what without too much difficulty. A list of my biomes: * Extensive Mountain Ranges * Long Mountain Slopes * Large Forests * Coastal Plains * Inland Plains/Grasslands * Large Swamps Notes: If you have a link to a list or lists, that would be great. Answers are equally welcome. The main biomes that I need information on are the mountain slopes/ranges and the forests, but information on all would be good. I'm interested in anything that could be traded, be it organic, manufactured, whatever. And finally, this is a medieval-ish setting (think LotR), so gauge the natural resources needed for that time setting appropriately. Additionally, if you know of information pertaining to deserts or tundra, that would also be appreciated, as future worlds might contain those settings. [Answer] Mountains could be a source of minerals/metals/rocks and gems/mines, ice/water, and home to rare flowers as well as goats and sheep. They could be similar to the Alps, Himalayas, Rockies or any other mountain range on Earth, so research those ecologies. This area may import wood for fires (for heat and foundries) and additional food, clothing and art from the lowlanders. *Note: very tall mountains have multiple ecologies from tundra at the peak to jungle at the base.* Check out [Altitudinal zonation on Wikipedia](https://en.wikipedia.org/wiki/Altitudinal_zonation) for more information. Long Mountain Slopes - see Mountains (these are the same). Forests provide wood (a good building material, also good for arts and crafts, paper, burning/fuel), mushrooms and deer/game (including buckskin and antler/bone tools). These people could want metal tools from the mountains, grains from the plains and fish from the coast. Note: there are several types of forest to research from rain forests and jungles to bayou to pine forest. The type of forest depends on latitude. [Here is a forest biome intro](http://www.ucmp.berkeley.edu/exhibits/biomes/forests.php) to start. Coastal Plains will probably provide seafood, salt, boats and trade goods from other coastal towns. They may want grains, clothing and such from inland farms, wood for their boats from the forest, metal tools and harpoons from the mountains. Biggest advantage here is trade from city to city across the water is probably faster than over land, so you could get a lot of exotic goods coming from far-away locations. Inland Plains/Grasslands will probably be the bread basket for the region because it's the best place to grow grains (like wheat) and raise animals like sheep (wool and meat), horses (transportation more than meat) and cows (milk, beef). They will need heating fuel (wood) and supplemental meat from the forest, metal tools from the mountains and whatever exotic goods/baubles are offered from the coastal cities. Swamps are also a very broad category. There are all kinds of wetlands including fens (mostly grasses), bogs (mostly peat) and bayous (mostly trees). Depending on which, you could have rice, cranberries, fish and birds. It would be a good source of fresh water. Residents will probably want to import metal tools from the mountains, clothing from the plains and boats from the coast. [Answer] Generally speaking, there are not many rules forbidding any ores on any kind of biome - however - * swamps would be a nightmare to mine, unless you are looking for bog or swamp gas * big plains tend to have all nice ores covered by big amounts of soil - however, there may be a good source of clay * hills and mountains tend to have easier access to ores (usually) There are some environments that would not be seriously settled (far north, desserts, mountains) - unless they have some desired resources. Think less about resources as such, but about logistics, especially waterways. It would seriously affect trade routes in a low tech setting. [Answer] I'd start by asking - who cares? This is a medieval(ish) world. 90+% of the people are subsistence farmers. Trade is, by our standards, almost nonexistent. Transportation is largely muscle-driven, and water travel (especially ocean travel) is hazardous. What long-range trade there is is pretty much confined to relatively high-value goods. This largely rules out trade in raw resources. Food, except luxury items like spices and wine, is local. Refined metal, rather than ores, and not a lot of that. No timber, except perhaps exotic woods. Manufactured goods, especially arms and cloth, can be shipped fairly long distances, but these would hardly be widely used. Wool cloth, for instance, is nice, but locally produced leather or linen is likely cheaper. The classic exception, Rome, requires careful thought. An important aspect of Rome's ability to encourage trade was its military might and political control. If you want large-scale trade, you need an empire. Another important factor is slavery. Slaves make cheap labor, and this cuts transportation costs. Are you sure you want a monolithic, oppressive government, and widespread slavery? In response to another answer, I'd point out that with the transportation available, importing firewood is a non-starter, unless the producing area is fabulously wealthy in some product. Likewise, trade in water is just ludicrous. The bulk and weight are simply too great. Ice is possible, since the Romans used it occasionally, but it was the height of luxury, and wildly expensive. Minerals/gems are where you find them. While the vertical exposure associated with mountains makes them somewhat preferred, placer deposits such as gold are found far from the sources, and eroded land also exposes lower strata. Consider the British tin mines of Cornwall and Dartmoor, which were the dominant source for millennia. The region is coastal, with elevations of no more than 2000 feet, and marked by gentle hills and valleys. [Answer] **Resources of the pre-modern world...** 1. Lead 2. Fresh Water 3. Salt 4. Tin 5. Bismuth 6. Zinc 7. Iron 8. Copper 9. Mercury 10. Nickel 11. Coal 12. Silver 13. Gold 14. Wood 15. Tameable Animals **Which resources where?** Lead and Silver are mined together and Lead is by-product of Silver Mining. Copper is usually mixed with Tin or Zinc, but can be found by itself. Mercury is used as a medicine and in mining of Silver. Zinc can't be found by itself and was undiscovered as it's own thing till much later. In the smelting and smithing process an alloy turned up that was valuable. Bismuth and Nickel were seen as "cheap" or worse versions of the other resources and found with them. I forget which though. Salt can be found virtually every where, but Salt Mines largely exist where Glaciers used to be... which is everywhere pretty much. Tin, Copper, Iron, and Gold are all found on eluvial plains. Lead, Zinc, Bismuth, Mercury, Silver, and Gold are found in Volanic areas (not volcanoes). Coal of different qualities is found in various places so there isn't a good answer for where it is other than define where swamps were 250 million years ago and thats where it will be today on those land masses. Also there are things called peat bogs that produces not very good coal in less time. You can also make it from wood. Hard to pin down, but mountains and swamps is where you'll find most coal mines Fresh Water is dictated by your landscape, as is wood. Tameable Animals is the difference between Cities and Nomads/small villages. I have not done much looking into this aspect but I need to soon. So where to put things? Basically, have to work the plate tectonics out so that you can figure out where the 3 type of sediments go. And then you can just randomly distribute all types that go in that sediment, keeping in ming that the only things that were Salt, Mercury, Copper, Iron, Gold, and Silver... of which you can say there were "Copper-Iron" "Gold" "Silver" "Mercury" and "Salt" mines. distributed pretty much like so... Aluvial area: "Copper-Iron" and "Gold" Volcanic Area: "Silver" and "Mercury" Everywhere: "Salt" Since Salt is "everywhere" and important, you can just toss it as placing correctly and instead just use it for story purposes since humans need salt and it fairly common, but still, there is only so much any single place can hold so its a reason to war and such in the past, but it became so easily accessible by the middle ages in other forms that it's hardly worth mentioning. Now the problem with placing any of the other 4 "accurately" is that any map that I have ever seen doesn't really help as it just has mines strewn about everywhere in any place that is considered to have these elements which indicates to me that mines are just where they are because that is where randomly, enough of the material was seen at that point that's where they started digging or they purposefully set up a camp there because it is secure and then just started digging till they hit something. Either way this means that 3 of the 4 is more or less just random. Mercury is however, as I understand it is found in lowlands and swamps due to how it gets pushed to the surface so there is some geology there at work, but where these things are also seems arbitrary to me, even though it probably isn't. Things to note however... Mercury limits Silver and Gold mining. How I don't know, but it's used in their mining so if you don't have Silver you can't mind those thus you're limited by it. Salt limits your overall work force since if humans don't get salt they die. Iron & Copper limits your overall military and production capacity due to if you can't get these materials you can't arm your soldiers/workers copitently. So from that perspective you can simply define your nation by some math where the stronger they are the more of those mines must be under their control and just balance the equation to figure out how many should be in the region that a nation in your world controls. To do that is a whole other topic, but the startin point for that is that for a government to control a place, from what I have looked into, they must be able to deploy a unit there within a month. To trade with a place effectively, a trader must take no longer than 1 year to get there. From that, you can see how much you can control and trade... in other words, All mines must be within a month of travel of military deployment, and that military must have enough power to maintain it's control, either from resources inside it, or traded to it. Hope that helps. It's a really hard question that I've never found any easy answers to and any answers that I did learn requires more and more knowledge about geology to answer 100% accurately. ]
[Question] [ We've made an important discovery. With the power of unobtainium and handwavium, a highly advanced species that lives in higher dimensional space has provided us a room on Earth that has its own passage of time. It's a gift to humanity, so an international agreement has been made to ensure that it's used properly. The doorway can't be moved and it can't be destroyed. **Here are the rules and magical properties the advanced species has laid out:** * When you enter the room, that room exists only for you and whoever enters the room with you before the door is shut. Once it's shut, if someone enters the room again, they get a copy of the room that exists only for them, and so forth. * Time continues normally within the room, but when you exit, it's as if you were only in the room for a brief moment. You continue to age within, so if you're in the room for 20 years, to outside observers you just aged 20 years within moments. * When you exit, the advanced species has ensured your safety from collision with other people who are exiting by placing your own unique exit door in a safe place (like your home). * The room contains a library of every book on Earth. When a new book is published (and has a record of it like ISBN or entry on Arxiv et al.), the library instantly has a copy. When you enter, it instantly has the latest copy of the internet, as well. So you can access every website and every subdirectory, but it won't get updated until you exit and come back. * Materials in the room stay in the room. You never run out of food or water, but the only things you can take out are things that you brought with you. * You can't communicate with the outside until you're back outside. * Physics holds within the room. You can hurt yourself and die in the room (and if no one came in with you, you can never be retrieved) and you can destroy things in the room, but if you leave and come back, everything is back to normal. **Edit - I've added some additional properties to answer some questions.** * The exit door cannot be entered. You must take the trip to enter again. * The room is powered so you can bring in your own computer (and yes, supercomputer components) or robot. Retrieval of the robot would have to involve the robot having enough intelligence to exit on its own since you can't communicate with it from the outside. * You can write things down on a notebook and leave with the notebook you brought and the writing will be maintained as long as you use a writing tool that you brought with you. **Dimensions and Amenities** * The library is sequestered in a long rectangular space (that always grows) with advanced moving parts that bring books of topics or titles you want close to you when you look for them. No one's ever been to the end to measure its size. * The main room is 10000 square feet and has a bed, a desk, and a wall mounted computer that runs the highest graphical/computer power available in the Nvidia/AMD market. The creators would rather you bring your own supercomputer. It's a fresh install of HandwaviumOS that can run any file or program. The internet is local and cannot connect to the outside world. * The kitchen is 500 square feet and contains a refrigerator which contains any food you tell it to contain. The creators have a lot of resources off-dimension. What effect would this have on society? How would it influence science and technology and affect the future growth of our civilisation or problems that we face today? [Answer] The passage of time itself is the unlimited commodity on offer; how can you apply that to existing industries? To me, this is more interesting to consider what you can accomplish with the effect of time on objects and processes, rather than people. I see several different economic opportunities: * "instantaneous" **aging of any food products whose value increases over time** *(wine, other liquors, cheese)* * speeding drug development by **running human medical trials** inside the room * running any sort of **lengthy computer processing** *(climate modelling, protein folding, cracking encryption)* * **decontamination of radioactive waste** via "accelerated" radioactive decay; retrieval unnecessary! *(idea courtesy of [lbotinelly](https://worldbuilding.stackexchange.com/users/863/lbotinelly)'s comment)* * other useful implementations of the process of **decomposition** * **propagating slow-growing plants** *(automated care system would be required)* There would be a boom in the market for **robotic automation** and "[rovers](http://vignette1.wikia.nocookie.net/stargate/images/0/09/StargateMALP-Large.png/revision/latest?cb=20110929191944)" to allow you to place objects into the room and retrieve them after a preset interval of time; there's no reason to keep humans in the loop! This would stimulate interesting advances in fault tolerant hardware & software. Easy retrieval but no communication is a flip-flop of the situation faced by our current planetary robotic probes. **Power generation** could also be a hurdle -- would you need to run everything off [RTGs](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator), or could you have rovers self-dock *(a la a Roomba charger)* with an existing power outlet provided in the room? If a human presence was required for "babysitting" certain objects, an **online marketplace to schedule room shifts** might spring up, so a long period could be completed in more manageable increments of time. Use of the room could be punitive in nature, as it basically amounts to solitary confinement. It could be used for **incarceration or prison work-release programs**. This would have serious ethical considerations, of course. This raises another question: can the door be barred from the outside? The big question: Is time passing faster in this room in relation to the outside world in an **absolute** sense -- is there a concrete function representing the ratio of time passed *(1 year in the room = 1 minute on the outside)*? Or does it only pass faster on the inside to a **human observer**? [Answer] This room has a second amazing benefit that's sort of hidden because it was presented more or less as a side effect in the original description: > > When you exit, the advanced species has ensured your safety from collision with other people who are exiting by placing your own unique exit door in a safe place (like your home). > > > This sounds to me like **instant, free teleportation**. Of course, the starting point is fixed, which is not optimal, but that's massively outweighed by the fact that exit portals could be placed in all kinds of places that are difficult or dangerous to get to. Workers trapped underground in a mine accident? Send a rescue party into the room with food, medical supplies and tools and ask the advanced species to locate the exit in the mine. Doing research and need to set up camp in the middle of the jungle or desert? Make the first half of your trip through the room. This could even work for the moon, Mars or further, once we develop the technology to retrieve people from those places, and assuming the door is large enough to bring vehicles through. (Or, if the exit is movable while the room is occupied—the original wording doesn't address this—people could go in, throw robots/sensors out the door, then wait for the advanced species to move the exit back to Earth before walking out themselves.) The other answers already cover a lot of ground with the primary (time) aspect of the room. I do want to add one thing: when I read the question, one of the first things I thought of was "wow, people would be able to finish school/get their PhDs a lot faster by studying in the room" (relative to the passage of time for the rest of us here on Earth). Yes, there would be a huge lack of human interaction in those school experiences, but people have been attending school via correspondence courses and online programs for a long time. It's not *too* hard to imagine intelligent, highly motivated (probably mostly introverted) people popping into the room, coming back out for exams, repeating for a few "semesters" and going from secondary education to thesis defense in just a few weeks or months. I say weeks or months instead of minutes or hours because the school thing makes the assumption that the human authorities have opened up use of the room to pretty much anyone, instead of just VIPs. In that case, a lot of people would probably want to take advantage of the opportunity, and there would be a fairly long line to get in. Some sort of bureaucracy would develop over room entry/usage rules ("Now serving number G39, we're ready to let the person with ticket G39 into the room..."). A small town would likely develop around the location of the entrance to the room, or if it was already in a populated area, a door visitor sub-economy would spring up, in the form of extra hotels, restaurants, co-working spaces, that sort of thing—the [Breezewood](https://en.wikipedia.org/wiki/Breezewood,_Pennsylvania) of superhuman travel, basically. On a societal level, we'd be forced to adapt our laws to account for time travel. A simple, trivial example: if you go into the room on your 15th birthday and live there for what feels to you like 10 years, are you 15 or 25 when you come out? Can you legally drink? Vote? [Answer] Wingman4l7 already listed some good things you could do with that room. However as with everything else, it would also be used for evil purposes. And also for those, there are ample possibilities: * The perfect murder: You enter the room together with the victim, kill the victim there, and leave the room. Nobody will ever find the corpse. If someone saw you enter the room, just claim the victim wanted to stay a bit longer, and you have no idea what happened; maybe the victim just decided to stay for the rest of his/her life. Nobody will be able to prove otherwise. * Similarly, if you want something to disappear forever (say some papers proving illegal business), you may take it into the room and leave it there. Since everyone gets a fresh room, whatever you leave there will be lost forever. * If you have to flee from the police, staying the rest of your life in that room, unreachable by the police, may be preferable to staying the rest of your life in prison. Especially since you can leave the room at any time should you ever change your mind. * Also, if you flee from the police, even if you immediately leave the room after entering it, the fact that the exit door may be anywhere can be helpful to hide your traces: You'll effectively have instantly moved to another point of the planet unknown to the police. * Forgers may value the near-instant ageing of materials. With enough people working for them, they could get that effect without the individual people ageing too much, by just passing the materials through the room several times, where each time someone else accompanies it, and each individual stay is not too long (say half a year). Given the library, the person can use the time inside to learn more about the stuff to forge. * The availability of the complete internet, coupled with nothing having an effect on the outside until you leave, is also perfect for black hat hackers trying to break into web sites. They have all the time of the world to look for vulnerabilities and, if they find them, copy out data, without anyone else noticing or being able to respond with counter measures, as the hacking will not be visible from the outside. [Answer] With infinite computing time, cryptography would be meaningless. Which means, no government or individual could keep any secrets, and anyone's money could be stolen at a moment's notice. If a crypto arms-race developed, hardware durability would be very important - your machines are still ageing in there. Scientific advancement would improve rapidly, and as mentioned in another answer, robotics would become important. The problem is, we aren't taking everything out of those rooms, and we're putting a lot of computers in. Humanity would rapidly run out of materials to make any kind of robots, computers, or even basic electronics. Either we would utterly wipe out our planet, or we would develop the technology to turn energy into matter, and make a room that generates infinite amounts of energy and pipes it out the exit door to replenish our rapidly shrinking planet. ]
[Question] [ This is the start of an experiment to see just how useful Worldbuilding Stack Exchange can be. I'm planning a work of fiction, but rather than build the world around the story, I'd like to write the story in the world - in other words, making the setting without thinking about how it will be used. To do it, I'd like to ask a series of questions on Worldbuilding that touch on different aspects of it - using the site to help me better hone the various facets of the setting. This is the first question. --- The setting so far is Victorian London - with a twist. Around the year 1850, massive coal deposits were discovered underneath central London (construction on the London Underground began roughly 15 years before it did in our world, and large-scale excavations started up quickly). Within five years, even larger seams had been found, and it became apparent that London was sitting on top of the largest coal seam discovered to that date. By the year 1895 - the date of this story - the Underground project has expanded in conjunction with new mining enterprises, and there is effectively a second city underground, populated by workers and their families. I'm not entirely sure how deep it will run - certainly many hundreds and hundreds of feet - but it is quite sprawling. The world underground is much different from the world aboveground, and as mining is the predominant occupation below the surface - at least, at first - it dominates society in a number of ways. For example, there have been changes to the language (English, of course) because slang terms have made their way into everyday speech. Here are some examples, based on their fictional technology: * "vehicle" $\to$ "c'lagon", an effective contraction of "coal wagon" that was generalized to most wheeled vehicles. * "lamp/light(bulb)" $\to$ "geordysword", reflecting an affectionate nickname given to a variant of [George Stephenson's lamp](http://en.wikipedia.org/wiki/George_Stephenson#The_miners'_safety_lamp) that became common in this world.1 I'd like to use common patterns in the jargon to create names, using in part some of the techniques suggested in [Are there techniques for creating alien or foreign sounding names?](https://worldbuilding.stackexchange.com/questions/3478/are-there-techniques-for-creating-alien-or-foreign-sounding-names). However, to do that I need to better understand the evolution of this new dialect/language to determine how much mixing is likely to happen, and on what timescales. **How long will it take jargon to turn into a dialect, and a dialect to then turn into a language?** It is realistic to expect a new dialect to form in 50 years, under these conditions? --- 1 This is in part an nod to the miners of Northumberland, though this term was never used ("Geordie" was and still is). The Stephenson lamp is one tie between the real world and this one. [Answer] ## Ah but you already have a ready-made one... the Thieves' Cant I think you may want to take a look at the [Thieves Cant](https://en.wikipedia.org/wiki/Thieves%27_cant), as beautifully illustrated in *[Cant - A Gentleman's Guide: The Language of Rogues in Georgian London](https://rads.stackoverflow.com/amzn/click/com/0992492203)*, by Stephen Hart. While that was the language of a more metaphorical underground, it should serve as a useful guide, and is great for inspiration to create a credible past. **It seems to have evolved in about 30 years**, as a reaction to the creation of the London police force. So well within your time-frame. A few interesting features: 1. **Numerous synonyms for relevant terms**, just like the Eskimos' alleged 40 words for snow. Consider the sheer number of synonyms for the word “steal”: Cloy, Do, Filch, File, Fleece, Give it to, Heave, Knap, and a dozen others. Or the myriad ways of referring to gallows: Chates, Crap, Gregorian Tree, Morning Drop, etc. 2. Sets of **replacement words** for generic nouns and verbs: 'ken' meant 'place', 'cheat' meant 'thing', as in "bleating cheat" would be a sheep. "Fake a ken" meant to "rob a place." 3. Most slang words are **short (and sweet)** 1 or 2 syllables at most, and yet are recognizably English: One can "snilch" or "york" at something and then decide to "fam" something, "milling" the victim if needed. 4. Lots of **derogatory words** for upper classes, cops, women, various minorities, ugly people, you name it. You don't wanna come across as a "Twiddle Poop" for instance. Now this dialect was made specifically to be difficult to grok by outsiders. Since you don't want your readers totally lost, you may want to introduce them more gradually to the dialect, perhaps through the eyes of some outsider interacting with someone who straddles both worlds. [Answer] There is a precedent for this, and it holds up well to what you are looking for. Cockney rhyming slang arose around the 1840s and became well established in only 20 years. It is completely impossible to understand unless you know it despite being mostly English words... <https://wikipedia.org/wiki/Rhyming_slang> > > It remains a matter of speculation whether rhyming slang was a linguistic accident, a game, or a cryptolect developed intentionally to confuse non-locals. If deliberate, it may also have been used to maintain a sense of community. It is possible that it was used in the marketplace to allow traders to talk amongst themselves in order to facilitate collusion, without customers knowing what they were saying. Another suggestion is that it may have been used by criminals (see thieves' cant) to confuse the police. > > > [Answer] Well, to have an historical reference, at the time of the fall of the Western Roman Empire, Latin was far from being spoken uniformily through all the territories. Yet, with invasion from different groups and all that, its successors began to be considered different languages several centuries later. Another example is that at the time of independence, South American Spanish was considerably different from European Spanish, yet they are still considered universally the same language. Language evolution is a very slow process... think that people sheldom change their language after they reach puberty, and that kids todays will still be heavily influence by the language in people in his 50s. A way to improve the speed would be mixing in your population groups that come from different backgrounds, so they end creating a *creole* or *patois* mixup language, but it would still need about one hundred years (and a society very isolated from the rest of London) to become their "mother language". [Answer] I don't think there's a hard and fast answer to this one, it depends in large part on how much contact the "underworlders" have with speakers of the mother tongue, if someone is constantly dealing with native speakers of mainstream English then you're not going to see their use of the language change much. Isolated populations will undergo change much more rapidly as slang terms come into common usage and then become fixed as daily terms. This process generally still takes decades but can be more rapid if it's deliberate on the part of the speakers, a deliberate effort to set themselves apart or to mimic an existing dialect that they view as prestigious. ]
[Question] [ In a world with rideable dragons, what skills would you look for in a knight, and how would they train for it? For this question, let's assume: * castles modified based on the accepted answer from [How would the existence of large rideable flying creatures have changed the design of castles?](https://worldbuilding.stackexchange.com/a/191/90) * dragons based on the question and its accepted answer from [How could dragons be explained without magic?](https://worldbuilding.stackexchange.com/a/345/90) (especially: young dragons are relatively small and can fly, old dragons are huge but cannot fly anymore — both can be mounted) * there still is the regular religion + nobility in charge (meaning that knights don't necessarily need to be all that skilled to become knights) * dragons are not too rare, meaning that mainly their price is impacted. Lesser knights won't have one but all the richer and/or better knights do. If you are riding a young dragon (say up to 2 times the size of a horse), you can fly. Otherwise, you are stuck to the ground. In any case, you can make your dragon spit fire, charge or fight. And from its back, you yourself can use any projectile weapon or maybe a lance. The enemy also has dragons. Now here's the question: because dragons are still quite expensive and dangerous, you don't give them to children nor inexperienced knights. So, **what sorts of skills would be required of knights then, and how would you then train to handle all the situations that may arise in battles that involve dragons?** What props do you use? What methods, what exercises, at what point should you get your first dragon... Problems to mention in your answer might include: * learning to "pilot" a dragon, with medieval tech, before you actually go to your first flight * learning to dodge dragons air strikes while battling on the ground * learning to fight with a small armor in case the dragon you were flying got killed (you can't wear heavy plates while flying) * what weapons do you need to master in a battle environment with dragons * ... Don't hesitate to draw more from other questions on this site! [Answer] This is something I considered a long time ago. Fighting against a flighty, mobile enemy such as a dragon, standard weapons training (Kunst das fetchens et al.) would be considerably less useful. On foot, these knights would have to be rather athletic and acrobatic. Attacking smaller flighty dragons would likely be the job of crossbowmen or longbowmen~ puncture its wings more than a couple of times and it will have trouble staying aloft. For the larger ground based ones, one assumes they get the dragon-standard: adamantine scales; so bolts become less effective. Instead, our athletic knights probably master things like pole-vaulting onto its back and then using tapered longswords or stilletos to penetrate the gaps between scales, whilst other parts of the division keep it distracted. This requires us to know how deadly dragonfire is, of course. If its 9 billion degrees or other such madness, distraction is merely going to be blowing raspberries in front of the beast and running like the clappers. If its less ridiculous than that; specialised tower shields with ground spikes might work, even if they are disposable. In general, these knights are not in full plate or even chainmail. A helm and a breastplate are probably all they have. No point having armour if a single tail swipe drops you on your ass helpless and ready to be clawed in the gut. They rely primarily on dodging. So overall, reflexes, perception, instinct. Courage can be militaristically drilled in if needed, but would also be needed. Strength and athleticism enough to do all that crazy. As you say, this is a lifelong career, not something a standard mercenary drops into very easily (though vice-versa is plausible). As a result, we assume there is special dragoon squad in every batallion of knights; this amount of training is probably too expensive logistically to give to the entire army, though those might get a 'Dragons 101' course if they're common opponents. EDIT: To consider your highlights **Dragon Defence~** Assuming you're talking about regular troops and we don't have magic; it would be difficult at the best of times. A keep away policy is likely best- long polearms and crossbows again. Again, this is all dependent on the range and potency of dragonsbreath. Dragons 101 may also cover the ability to rapidly disperse formation in an orderly fashion. This is typically suicidal on a regular battlefield, but here it would be advantageous to get out of phalanx and beat the creatures from as many angles of attack as possible. Although this assumes that, regardless of its general potency, it can still be zerg-rushed to an extent. If its good at blowing flankers away with its wings and tail, keep away is the only thing you have, I'm afraid. **Fighting from the back:** Long lances or poleaxes. Assuming the dragon also has a weight limit, we don't want our riders in heavy armour again. The training for this is mostly going to be akin to light cavalry training: rideby attacks and disruption, something our dragoneers will excel in. After all whats more disruptive in a field battle than something that forces you to break formation? **Props for training** Probably an assault course. Depending on the level of mechanics in the setting, it should have as many unpredictable moving sections as possible. Early training menus may start with lesser beasts (bull-fighting etc.) to get people used to it. Attemping to ride wild horses is another good start. Or, if dragon-taming is at such a level where a normally docile beast can get aggressive on command for the purposes of training, then that is the probably the best of all. For this, they could use fake polearms and plant flags or something rather than stabbing it obviously. EDIT 2: Didn't notice castle design as a parameter before. Did I miss it? Anyway~ **Castle Design:** First and foremost, eliminating 'firing lanes' is critical. You don't want the dragon to be able to fly straight over your courtyard. Hence, you place towers in unsymmetrical locations so if a dragon wants to fly over your castle and blast with fire, its gotta take a really curvy route. Secondly, you add diagonally upwards facing spikes to your crenulated walls, so a fly by attack against guys on the battlements is more difficult. Thirdly, you add in murder strips, so if our silly dragon does fly the curvy route, it gets to a point in the defence where it gets barraged from shots from both sides. Again, all of this depends on the range of dragonfire. If our dragon can sit half a mile in the air, out of arrow reach, and lay some carpet napalm, no ground defence is going to be of any use. Furthermore, I'm not an architect so as for the feasibility of constructing these things, I wouldn't know. [Answer] Horses are also large and dangerous, though not as large and dangerous as the posited dragons. It may be worth looking at real life horse and rider training. As it happens, my riding instructor is also teaching her four-year-old granddaughter. The granddaughter does not ride a young horse. She rides a senior citizen of a horse that prefers a slow walk and takes a been-there, done-that attitude to anything that happens during trail rides. As she gets bigger and more skilled, and the horse continues to get older and stiffer, that arrangement can't last forever. Another horse is being trained to take over as the granddaughter's primary mount, but as a young, inexperienced horse it is currently being ridden only by the most skilled riders. I assume a young dragon rider's first experience would be on a very old, experienced, ground-only dragon that is fully trained but retired from charging around carrying an adult wearing armor. Once the trainee has learned to ride correctly on the ground they could advance to riding one of the oldest flying dragons, probably one that can only just fly even without a rider, and prefers to walk. Ideally, it would only fly if cued correctly and firmly, and any lapse on its rider's part would result in it landing to rest its wings. During this process, the trainee would also be learning skills such as mounted archery. The young knight would have many years of practice at dragon-riding and related skills before getting on a battle-ready flying dragon, and still more practice before undertaking the training of a baby dragon. [Answer] Dragon riders will need alot of skill to control their mount, and do anything usefull in battle. Depending on strenght of dragon, a group of them will need to be used, so that will require some sort of formation, different for aerial combat, and different for land. That means alot of training for rider and dragon. Horses used in battles, atleast by units like Polish Hussars had to be trained, and each hussar had to bring few of them in case one dies in battle. This could be similar for dragons, depending on their survavilabity in battles. Add the maintance cost of dragons, and you have a mount reserved for richest who are skilled enought to ride them. **Young dragons**. Those young enought to be capable of flying would make great scouts and messagers. Being able to send message to isolated or sieged units, detecting enemy movements would make a great addition to every army. In battles, they could be used to disorganize enemy ranks, by attacking them with short bursts of fire, just enought to make them break formation and to be able to repeat this action few more times. Rider would be limited to pilot in air-ground fightes, unless he's given a bow. Any meele weapons are out of question because it would require dragon to land or get close to enemy. **Old dragons**. Too heavy to fly, they would be tanks of their times. Large and strong enought to hold heavy armored rider, they would stomp over enemy, and break their ranks just by walking over them. And if they somehow stand ground, fire will help. Again, knight would be just a pilot, he's too high on dragon, too far from enemy to do any fight. It would be up to dragon to kill enemy. This is would be good for nobles, because they risk less and contribute more at the same time. Those dragons wouldn't stop after initial charge if possible, so they don't get surrounded and killed, they need to keep momentum. They would retreat and repeat the charge like hussars, or try to push forward while followed by humans who will keep their distance behind them, to avoid being killed by "friendly" dragon. **Training of Rider** Dragons can be tamed, so people know their behaviour and what can be done with them. This means, training of rider should start with series of lectures, where experienced rider will pass his knowledge about dragons. Theory before practice is required, because there is huge chance of dragon killing his new rider when misshandled. Or worser, it would be trained incorrectly and try to break free. We are talking about nobles here, they have alot of time, so they can start at young age. After theory, they will be given their first mount. Depending on how fast dragon grows, he should be large enought to carry a kid. If the kid has a chance to grow up with a dragon, he can adjust to constant change of dragon size, and will not be afraid when he gets to ride larger version. As he will start with flying ones, he will have to do alot of acrobatic training, he has to be agile, to be able to mount dragon, and perform actions that will force dragon to fly where he wants. At this point, kid should be taken as passanger for a ride with older knight. They will perform few crazy maneuver to check if young one won't pass out. This will decide if they are capable of air fights, or will they remain scouts. If they pass the test, they will fly few more times with instructor, who will show them how to control flight of dragons with set of lines and pedals (How to train your Dragon comes to my mind). This is why agility training was required at early age. Then he will start training with his own dragon, who should be old enought to fly with rider, and still too weak to perform maneuvers that might kill unexperienced rider. At this point rider should know how to handle his dragon and how to fly. In battle his role is limited to this, so that's why those two skills are focus of training. Archery would be limited to air-air combat, when riders might attempt taking out other riders. Attacking ground would be to limited because of dragon body and wings obscuring most of targets. **Training of Dragon**. This would be similar to horse training probably. They would need to be guided multiple times through every maneuvers so they can remember and perform it on command. Training will be done on special fields, with high structures, made of wood, which will form a track. The more expierenced the dragon is, the harder the track would be. Gradual progression from track to track, will make sure that dragon can perform required actions like tight turns or barrel rolls. It should also detect limits of certain dragon. It's a living being, they are all different. At some point they will also have to be kept for a long time in loudy place, so they will get used to battle noise. When dragon is prepared, new training form will be introduced. He will have to pass "friendly army" test. That means walking via field will of dummy representing friendly humans and not damaging any of them. This will make sure he obeys they order, and can, alteast for certain amount of time be kept with the rest of army. **Dodging air strikes in battle**. If only one side is capable of deploying dragons, in numbers that will matter (for example 1 young dragon in battle of thousands might do nothing significant) then enemy job will be to avoid battles on open field. They will search for covers like hills, mountains, valleys, anything where dragons has to fly a certain paths. In place like that you can dedicate small part of your forces to attack passing by dragons with ranged weapons. This is not ideal, but probably the best you can do. If both sides have dragons, it might turn the first phase of battle into series of skirmish for air superiority. The same way there were skirmisher fighting before main units clashes. Ground unit will either wait for result of air battle, and then decide what to do. If they loose, they might retreat and search for ground that will give them some defense from air attacks. Another tactic would be to attack while air fights are still in progress. This will limit usage of fire as it could potentially burn ally forces. [Answer] This isn't my original thought, but unfortunately I don't remember exactly who I heard this from. Basically a knight riding a dragon would look nothing like a knight on horseback in terms of training, battlefield utility, or weaponry. This is for several reasons. 1. Reach. A mounted knight has to be able to reach the enemy with their weaponry in order to be effective. On a horse it's relatively easy because the horse is comparatively small and therefore a human on horseback can strike nearby foes with a sword or a lance. However on dragonback a dragon is just too large to efficiently reach foes with a melee weapon, especially if the dragon has a long neck. In order for a sword or lance to be long enough to hit the target the weapons would have to be so long they could easily break or swinging the weapon around could damage the dragon's wings. Better weapons would be either a bow and arrow (especially since the dragon can carry more ammunition than a horse can) or dropping weights from the air. 2. The mount is better armed than the rider. For knights on horseback, a horse has limited ways of fighting beyond rearing and kicking the foe. A dragon has teeth, claws, and fire breath. From a militaristic perspective, putting a human on dragonback does not increase the tactical efficiency of a dragon at all and only serves to control the dragon. The end result of this is that a dragonrider would look less like a knight on horseback and more like a mahout controlling a war elephant. A dragon rider isn't really fighting so much as steering a big, armored, fire-breathing reptile into a horde of their enemies and letting the dragon do the fighting for them. This would probably result in riders who are good at controlling their dragons or flying them, but are absolutely terrible as actual combatants because they are sitting on top of their giant killer reptile and watching. There would also be concerns about dragons being more dangerous to their own troops than the enemy and might require special protocol to be euthanized if they go out of control, similar to IRL war elephants, but I don't know your dragons' temperatments so I don't know if they are likely to go berserk. [Answer] I think that fighting in a dragon's back should be very difficult and dangerous for the knight and even, for the dragon. Knights should work as a special operation command. Several knights may ride a dragon. The dragons may put them in a specific place and then, they perform their mission taking advantage of the confusion: kidnapping, killing, robbery of a precious artifact, destroy key buildings like bridges, etc. The way of defending of them should be using heavy crossbow to damage their wings to push them to land and become an easier target. [Answer] Naomi Novik explores this topic in depth in her *Temeraire* series. The series takes place during the Napoleonic wars. During this time, nations have, in additions to armies and navies, air forces composed of dragon riders and their support teams. Naoimi's dragons are often large enough to support a whole crew that can board other dragons or drop bombs, and also ground crews that take care of bedding, feeding, and medical needs. see <https://en.wikipedia.org/wiki/His_Majesty%27s_Dragon> ]
[Question] [ When I was a kid, I read an essay by Asimov describing an *inside-out asteroid*: (summary from Wikipedia) > > The Bubbleworld or Inside/Outside concept was originated by Dandridge > M. Cole in 1964. The concept calls for drilling a tunnel through > the longest axis of a large asteroid of iron or nickel-iron > composition and filling it with a volatile substance, possibly water. > A very large solar reflector would be constructed nearby, focusing > solar heat onto the asteroid, first to weld and seal the tunnel ends, > then more diffusely to slowly heat the entire outer surface. As the > metal softens, the water inside expands and inflates the mass, while > rotational forces help shape it into a cylindrical form. Once expanded > and allowed to cool, it can be spun to produce artificial gravity, and > the interior filled with soil, air and water. By creating a slight > bulge in the middle of the cylinder, a ring-shaped lake can be made to > form. Reflectors will allow sunlight to enter and to be directed where > needed. > > > ![inside out asteroid - external](https://i.stack.imgur.com/Qy5Ya.jpg) ![inside out asteroid - internal](https://i.stack.imgur.com/Lnbju.jpg) The vintage illustrations may look like an [O’Neill Cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder), but actually are a **decade earlier** than that concept, from Dandridge Cole’s 1965 book *Beyond Tomorrow: The Next 50 Years in Space*. Well, it’s 50 years later **now** and still dreaming about space exploration. I can’t find the Asimov essay that I recall and other websites allude to. If anyone knows, feel free to edit. **Update:** It seems to be [*There's No Place like Spome*](http://www.wikipedia.org/wiki/Spome) in [this collection](http://www.isfdb.org/cgi-bin/pl.cgi?18587). **Update²:** No, it’s not. That essay mentions how they could spread across the galaxy, but doesn't go describe blowing up with mirrors. **Update³:** It might be Larry Niven, not Asimov. [Another post](https://worldbuilding.stackexchange.com/q/214326/885) describes the blowing up with mirrors as being from [*Bigger Than Worlds*](https://en.wikipedia.org/wiki/Bigger_Than_Worlds). Nivin may have been relating the idea from the original paper by Cole; perhaps many popularizers related the idea. But this seems a likely candidate for the copy I may have actually read, as I do remember [the collection it appeared in](https://en.wikipedia.org/wiki/A_Hole_in_Space). Besides building habitats by blowing up metal asteroids like balloons, Asimov described (related from the more esoteric stuff *he* was reading, to some extent) not just “a city” but a civilisation: many such bubble-worlds would both co-operate and do their own unique thing. They may even be cast away like dandelion seeds in the wind, colonizing other star systems by people who never really leave home nor feel great attachment to the home system: political differences or the urge for exploration? Just cast off. I was fascinated by this idea, and used it as the setting of a number of high-school writing assignments. That was pre-computer, so I don’t have any surviving hand-written manuscripts, I'm sad to say. --- So inspired by the [fortnightly topic challenge](http://meta.worldbuilding.stackexchange.com/questions/1966/fortnightly-topic-challenge-5-city-design?cb=1) to break my long streak at posting Answers but not new Questions, I’m bringing this to the attention of worldbuilding enthusiasts of the 21st century, exactly 50 years after it was initially imagined. **How would we design cities in bubble shells formed by blowing up miles-wide drops of molten iron/nickel?** We have general ideas in fiction about spinning cylinders with a ring-band lake and happy parkland wrapping around to the sky. Maybe we’ll have parkland facing the large hollow area and houses and industry below (more toward the outside). But is that still the logical conclusion? Such a unit might be small by human population standards: one city. But is it a Tokyo or Manhattan type city? Even so, it doesn’t need to be a self-sufficient *nation* because there will be many cooperating cities. Could they become very specialized, such as for a single “company town”? I’m especially interested in approaches that have not been considered in well-known SF before (which seems dated), and practical considerations that have been ignored in stories that just postulate it as a setting. [Answer] Let's start with a size. Just for grins, assume the interior is a cylinder 1 km in diameter with a 10 km length (that's 6 miles long). It will have to rotate at a bit over 1 rpm to provide 1 g at the inner surface. Total surface area is about 30 km², or about 12 square miles. Construction. Let's assume a final wall thickness of 100 meters. The total wall volume is about 3.6 km³, so the original asteroid had to be about 2 km in diameter. Absolute minimum power level required to melt this chunk of iron will be ~ 8 TW, since at melting point it will be radiating about 300 kW per square meter in blackbody radiation. At earth orbit, that will require a bit more than 5 million square kilometers of mirror. That's a circular mirror about 2500 km in diameter. Lighting: To provide normal daylight levels (1 kW / m²) over the entire surface, the total power will be about 30 GW. Pushing this through a port in the end cap will be hazardous. If you assume a 100 m diameter window, the power levels at the window will be just about 1 MW / m², or 1000 times the brightness the sun. This beam will have to be sent down the axis with a series of mirrors all the way down the axis to spread the light out to the surface. So the axis will be very definitely off-limits. And frankly, I don't know quite how to specify a high-quality window 100 meters in diameter which will contain 10 to 15 psi. It will have to be one piece, I suspect, since if you make it out of panels the supporting structure will have to take high temperatures (due to the power flux) and still be strong enough to hold together under the pressure. Titanium/sapphire, perhaps? I'm not sure about cost for this project. Since the colony fabrication required a truly humongous mirror array, producing the necessary light levels (even at Outer System distances) shouldn't be a real problem. Pressure compartments. This would seem to be a good idea, as Thucydides has pointed out, but the problem of light transmission remains. The more the compartmentalization, the more windows you need, and the weaker the structure becomes. Population. It's probably a good idea to assume that a colony should be self-sufficient in terms of food, since food production is essentially a zero-sum game over the total community of colonies. So how much area do you need to feed people? Let's assume a semi (but not completely) vegetarian lifestyle, and go with 1 acre per person. I'd rather use 2 acres, but let's say the long daylight cycle will increase productivity. Meat is rabbits, fish and chickens, but no cows. 1 acre is roughly 4000 m², so the total internal area will support about 7500 people. That's a pretty small town, so something like representative democracy ought to work. Note that you can't get around this by assuming multi-level farms: it's light levels that are the limiting factor. Also to be considered is the need to recycle water and extract nitrates and phosphates. Since the system is a closed one, you can't keep adding fertilizer to keep up crop yields without poisoning the ecosystem. Also to be considered is the capital cost of soil. 30 million m² of dirt 1 foot deep will total about 10 km³. Nickel-iron asteroids have about 30% impurities such as silicates that conceivably could provide the basis for rock/sand/dirt, but it seems to take a lot of hand-waving to explain exactly how that would be separated from what was originally a molten blob. Again, I'm wondering about cost. Space distribution. An obvious approach would be to build living quarters up the sides of the end caps. With a total cap area of about 1.5 million square meters, that's about 200 square meters per person. Note that that's not floor space, but window space. If the living space extends 100 meters along the axis at both ends, you only lose 200 meters out of 10 km, or 5% of your farmland, and total living space is about 20,000 m³ meters per person. Even allowing for common space and infrastructure, it seems adequate. It's a tossup as to which area would be more desirable — up towards the axis or down towards the surface. The natural first tendency to go for the axis has two things going for it — exclusivity (there's less area available) and low g luxury. The less-obvious drawback to this is that living at low g's is bad for one's health. The next obvious approach is the make the cylinder walls in multiple layers, with agriculture on the "roof", and industry "underneath". Since the materials involved are presumably nickel-steel, this ought to be straightforward, but rust due to groundwater might be a real long-term structural integrity problem. Industrial areas can obviously use artificial light. Self-suffiency. As I mentioned in the farming section, I don't think that specialized "farm-habitats" make a lot of sense. In addition to the basic question of light levels needed, transportation would be a problem. Assume a habitat has specialized in something (industry, let's say) and has a population of 100,000, which isn't much by terrestrial standards. It will need something like 5 pounds of supplies per person per day, or 250 tons per day. Moving that sort of tonnage by spaceship is a bit iffy. Half of it (food) is fairly perishable, which means that transport needs a fairly high average speed over relatively low distances, which in turn implies high thrust. Worse, any technology has to be reactantless, since reaction mass is lost and has to be imported, and this is not likely to be developed Real Soon Now. (Photon drives are reactantless, it's true. At high thrust they make really excellent death rays, and traffic control gets very touchy.) Specialization. Although each colony would be close to self-sufficient, there are intellectual economies of scale in technological activities, which might or might not be offset by ready communication. (Some companies have found, for instance, that outsourcing creates as many problems as it solves. Face-to-face meetings can be a very good thing.) This could lead to specialization among colonies, but would always be constrained by the cost of transportation of finished goods. Particularly, if local fabrication becomes simple (think of 3D printers on steroids), colonies might well become niche designers, with designs being sold and distributed rather than finished products or parts. Dissemination of artwork would be simple enough for writers and visual artists, and craft art (pottery, sculpture, paintings, custom artifacts, etc) would probably be cheap enough to ship to allow artist colonies to be established, although the need to provide food and basic services would keep the artistic population in check. Also, it might become standard in viable colonies (that don't tear themselves apart with internal conflicts) to require everyone to put in a certain amount of agricultural labor. To do otherwise would encourage a social split between the farmers and the (artists/engineers/bureaucrats/etc) which would have the potential to end very badly. [Answer] Creating a space inside an asteroid is probably the simple part (you could simply dig out the interior), but your question is more about what happens afterwards. Most designs call for massive open space inside, but for safety I suspect it would make a lot more sense to have the interior full of "bubbles" so any issues like a puncture or disease don't spread or cause cascade failure. This also allows you to isolate activities like agriculture, industry and other things so they don't interfere with each other. Illumination could come from a mirror of any arbitrary size (even out into the Kruiper belt). Having the spin axis pointed at the sun allows the mirrors to focus the light into the asteroid, while the pole opposite the mirror can be clear to allow for spacecraft to dock without impediment. The central axis would probably have a cable for transportation between poles, and more bubbles could be hanging from the cable to make a free fall "suburb" inside the asteroid. Since the asteroid will be full of ice and other valuable raw materials, a large part of it will be a mining site, although probably covered from view for most of the people who live inside the asteroid. As for being a "nation", it has the potential to be a very large city state due to the three dimensional nature of the interior volume, and millions of people could be living inside. Because the actual spacing of asteroids is so far apart, they will be largely isolated and independent of each other. If they are city states, then the future might be a reprise of the ancient past, with the asteroids becoming much like the city states of classical Greece. [Answer] The main problem I see here is retaining your atmosphere. Rock is all very good for building on but it is far from air-tight. Your spinning cylinder forces air against the rocky walls, acting as a **centrifuge for diffusing your oxygen in the rock** and, eventually, having it escape out the other side and into space. [Here is quite a neat experiment](https://www.researchgate.net/publication/269601907_Centrifuge_Modeling_of_Diffusion_through_Rock_Mass) showing the diffusion of gasses through rock in a centrifuge. If you want to use this as a seed ship spinning at 1g and still retain your oxygen between stars you need something to combat this. Either design a nonporous coating of outside of the city with to retain the oxygen. Even melted rock would still absorb some oxygen and result in a loss. Or we **fill the rock with another, denser (but non-reactive) gas first**. You fill the balloon of nickle/iron with this gas (lets say argon) and then the same centrifugal forces push it out into the gaps in the rock where it takes longer to pass through and provides a barrier against your oxygen doing the same thing. One problem, however, would be that if the asteroid was made to slow down its spinning then the heavy gas would rise back up through the rock and suffocate everyone at ground level...not pretty but perhaps a plot device... [Answer] First question that I think needs to be asked is whether there are in fact such things as nickel-iron asteroids of that size. We do have half a century more science to build on, and spacecraft have visited several asteroids. My impression from casual reading of the findings is that most smaller asteroids are in fact rather weakly-consolidated "rubble piles". which means you'd have to do a lot more material processing to turn them into a working habitat. [Answer] ## You don't inflate the asteroid, you separate it out, then inflate/spin the iron to make a shell. 1. asteroids that size are rarely solid, instead they are [rubble piles](https://en.wikipedia.org/wiki/Rubble_pile), so you first burn off all your volatiles (and capture them) then you have to melt your metals in a container that you can inflate along with it, upside by spinning it along with inflating it you can get decent control of the thickness. 2. then you build your internal struts and compartments. it needs to be reinforced if you plan to spin it for gravity. 3. once you have your airtight shell, you cover it with layers of solidified rock. The rock is both your radiation shield and your impact shield. this is also when you cut holes in it. 2 and 3 can be done at the same time. 4. now you put some of your gasses back in and build your habitat. the key to this is using rock/mining slag to coat the outside, either as bound rubble or remolded coating. this will look like an asteroid, and provides cheap durable radiation shielding. ## Or you just drill a hole. the other option is find the rare solid asteroid of the right size, drill a big hole in it, sort of hollow it out, maybe 30–40% of its volume at most. then you melts some iron and coat the inside with it to make it air tight. This is less structurally sound but easier to make. This can only make small constructs however. [Answer] ## This is my favourite topic of thought. I absolutely love O'Neill Cylinder concepts and I think conceivably they are the best solution for future humans to exist in. So here are my thoughts: First let's get something cleared up about Farming - it actually **makes little sense for any farms to be in an O'Neill Cylinder**. In terms of resources, it would be far easier to have hydroponic, or aeroponic, automated satellite farms in zero gravity nearby. Optimised in environment for maximum yield, able to re-use water and injected nutrients, controlled in space, these would produce the most food per cubic unit of volume. Similarly, meat production would likely be cultured meat - it makes no sense to have cows or chickens using valuable space inefficiently when robots can make these in zero-g environments in ultra dense satellites attached to the cylinder. And industry - in reality, it is **much easier for robots and computers to actually do production**, which would happen in space. Humans can still programme or coordinate, but the role of work would definitely be less primary and secondary industries and more tertiary or entertainment. So what is left? **Commerce and Lifestyle**. So living in an O'Neill cylinders, now removed of the need to be food generators, can now concentrate on Commerce and Lifestyle - and what possibilities! **A true 3-Dimensional entertainment and commerce city** With the advantage of normal gravity at the edge, and zero-g in the centre, you could really have a major entertainment focus: * Imagine an enormous cruise ship, with slides, cinemas, rides, gyms, function halls, restaurants in an amazing 3-dimensional matrix of varying fun experience. Your kids would have a ball of a time! (While you do your serious discussions with other adults on the edge at 1g) * Zero-g sports arena in the middle for the best Olympics or competitive sports ever * A continuous looping ocean Cylinder, for those sailing enthusiasts, with controlled weather. * A jungle Cylinder, with plants linking one end to the other, people living in low-g tree houses, having a ball of a time, or intently studying ecosystems * A marketplace Cylinder. Imagine the Grand Bazaar of Istanbul, but in a huge 3-dimensional matrix with different gravity areas. Goods and services can be transported and distributed throughout easily via arteries, and commerce could occur in all sorts of environments. A low-g haircut, or beauty therapy, zero-g boardrooms and university lecture theatres, or even high-g fitness centres! The possibilities are just mind-bogglingly numerous, and exciting beyond belief. It may actually be that with all of the above, and your ability to visit many different types of cities and cylinders, that other possibilities may yet reveal themselves that we haven't even dreamt of... ]
[Question] [ I imagine a biological creature, let's call it 'Marco' for now. Marco can vomit living slimes that survive by attaching to the ground and by doing photosynthesis, at first soft can be shaped and modeled before it hardens permanently. When hardened it can fuse with other slimes vomited to form various structures. The slimes are made of living mass that can be eaten again by Marco but are poisonous to anyone else. Marco has managed to create a living underground bunker to defend from other creatures, the bunker looks something like this, outer bio-structure with underground space. [![Picture depcits the Zerg, an alien species from the game Starcraft, who build living structures from their larvae](https://i.stack.imgur.com/fjeOS.jpg)](https://i.stack.imgur.com/fjeOS.jpg) My question is, can a creature like Marco evolve naturally without being created by gods or mad scientists? [Answer] Marco is a farmer. The placement of slimes for later retrieval once they have bulked up their biomass photosynthetically seems like a kind of farming to me. I am reminded of leaf cutter ants. <https://en.wikipedia.org/wiki/Leafcutter_ant> The ants cultivate fungi, not photosynthetic organisms. But their colony is made of this fungal matter, just as you want Marco to build his fort out of his exosymbiotic slimes. Here is a leaf cutter ant nest structure made of fungus, leaves and ant secretions. [![leafcutter ant colony](https://i.stack.imgur.com/PTBhs.jpg)](https://i.stack.imgur.com/PTBhs.jpg) <http://www.leafcuttingants.com/coloniesforsale.html> As regards symbiotic photosynthetic organisms, lots of creatures have these (sponges, corals, lichens) but all that I am aware of keep the symbionts - endosymbionts - safe within their own tissues. The ants have exosymbiotic fungi outside their tissues but they are guarded in the nest. There are definitely symbiotic relationships between ants and plants, and the plants even make structures to help the ants, but it is not the same as the leaf cutter ants (or Marco) building new structures out of the exosymbiotic organism and associated material. I think the problem with photosynthetic exosymbionts as you propose (the slimes) is they are not inside Marco and they must be in the sun, and so would be susceptible to being eaten by other things when Marco is away. You knew this too and so made the slimes toxic to all but Marco - that could work. But what about conspecifics of Marco's species? Presumably there are others. Marco's cousin could show up and eat Marco's slimes while he was elsewhere. Maybe the Marco creatures have territories they defend from conspecifics - that would make sense. I like this idea. The idea of a territory used to farm photosynthetic exosymbionts makes sense. It is so sensible I feel like it must happen but I cannot think of an example. Still thinking... As regards building things out of your exosymbionts, why not? The leaf cutter ants do. You could build out of a tough, woody, lichen-like exosymbiont / slime. [Answer] What you propose is a variant of what already exists in some cases: some animals eat fruits of plants. They poop the seed, the seeds grow and make a new plant (which makes photosynthesis) and produces new fruits which can be eaten by the same kind of animals. Since you want to enhance the specificity of the relation, you can go for a symbiotic relation between Marco and another organism: the organism recognizes Marco's antigen and vice-versa ensuring mutual tolerance. ]
[Question] [ On Earth, we use taxonomy to organize biological organisms into an identifiable hierarchy in which organisms that are evolutionarily related are placed in close proximity. This evolutionary approach to classification is a fairly recent innovation, dating back to Charles Darwin's publication of "Origin of Species." As we Earthlings begin to move away from our little life-bearing planet, we will no doubt begin to discover organisms, living or dead, on foreign worlds (the odds are in our favor that life exists/existed somewhere other than Earth). Humans, being human, like order and like things to be neatly sorted. These new organisms would almost certainly go through the taxonomic system to be placed somewhere in the Hierarchy of Life (copyright pending), but here we face a complication. Extraterrestrial life is highly unlikely to have evolved in the same manner as Earth life, and with even less likelihood of having a common ancestor. Our current taxonomic system utilizes evolution as a key factor in classification, but we can't know the evolution of extraterrestrial life without spending years doing field and lab work to determine how organisms are related, and short-lived, fast-paced humans want answers *now*. Enter xenotaxonomy: the science of categorizing extraterrestrial life. On a given world, evolution may have evolved creatures unlike anything on Earth, or maybe creatures like we see in our myths, but not in real life: dragons, giant sea serpents, griffons, etc. **What would an effective xenotaxanomic system look like, given the desire both to have answers quickly and for the resulting hierarchy to be clear and stable?** [Answer] ### Stable? Impossible. Large changes to Earth's taxonomy have changed even in the last 20 years. As we get more into using DNA to map things more changes happen. We've discovered that things that look alike are not always closely related (they just both hit upon a successful design) and just because they are very different doesn't mean they can't be related. So, with our current system we would try to start with large groups that make sense 'now' and we would have to be willing to modify any level in the future should actual life prove to not fit what we start with. We wouldn't really need to have just 'Earth' and 'Extra-Earth' labels. I think having the location would become important too. * System: Sol * Planet: Earth * Kingdom: Animalia * Phylum: Chordata * Class: Mammalia * Order: Primates * Suborder: Haplorhini * Family: Hominidae * Genus: Homo * Species: H. sapiens We, of course, would try to compare new life to what we know, but it will still be different and starting this way would keep things in better order, so even if we put something in 'animalia' on another planet it will still be preferaced by *WHERE* this animal was discovered. Since the chances are (unless interferred with by an outside visitor) all the life on the planet will be much closer related to each other than they would be to us or anything on Earth. [Answer] There are two options for categorizing life forms found on other planets/moons etc. # Method 1 Categorize life forms with respect to their location in the universe. For example we could have a naming system where creatures were named a, b, c, d etc after their planet name. So we could have Kepler-442b-a1 (species a1 living on Kepler-442b planet). This would be very suitable method of identifying *where* that life belongs to. Suitable for space scientists. # Method 2 Categorize life forms with respect to their chemical composition and respiration type. So we could have a CHO-Fe-O creature (body based on hydrocarbon and oxygen. uses iron oxidation respiration system). This naming system is more comfortable for biologists who are more interested in composition of organisms instead of where they belong to. [Answer] **Use a taxonomic system similar to what scientists used in the 1800s** and then advance it as research progresses. As the OP states, it takes years/decades/centuries to work out a "correct" [taxonomic system](https://en.wikipedia.org/wiki/Taxonomy_(biology)#History_of_taxonomy). Science on Earth went through at least three evolutions before settling on the modern one. *Early systems* were based on phenotypical similarities that could be observed with the naked eye. Each new observation technology has shaped and altered our understanding of the animal taxonomy. First, high quality optics allowed closer inspection of animal morphology. More recently, DNA sequencing has added another insight into how animals relate to each other. **Xenotaxonomy** A xenotaxonomy for a given world will incorporate all the meta-taxonomy that we have derived from Earth's taxonomic structure. We know about evolution and how it works. We know about sexual and environmental selection pressures. So, while the new biosphere didn't evolve similar to how our biosphere evolved (that'd be really crazy if it did follow the same general track), we do know that it *did* evolve and we can use that as a starting point to identify and classify species and families. [Answer] It should be completely independent from Earth's life taxonomic. Specially if their biochemistry is very different (like using ammonia instead of water or silicon instead of carbon, different amminoacids, not based on DNA and RNA, etc). In fact, how would you classify a jelly photosynthesizing three-headed and ten-legged creature living in ammonia's oceans that features spider-shaped cells with a sulfur-reducing organelles containing [TNA](https://en.wikipedia.org/wiki/Threose_nucleic_acid) capable of migrating in and out cells? Is this an animal? A plant? A fungus? A bacteria? No, it is something completely unrelated and different to what we have in Earth, so our taxonomy is completely worthless to them. If the biochemistry is similar's to Earth one. You could at most have some creatures classifiable as weird and uncommon types of bacteria and viruses, but any earthly taxonomic classification beyond that would likely be completely invalid and unsuitable for those alien beings. [Answer] We need to consider: * the entire range of evolution, including possible 'post-singularity' entities that direct their own evolution ('provolve'). The taxonomy of 'provolvers' looks very different to 'evolver's, but perhaps when all provolvers are evaluated, patterns emerge by which to classify them. In any case, a single unified system would need to cover both evolvers and pro-volvers. * the basic physical form of the entity in terms of the phase of matter that it utilises. Most life as we think of it uses the solid/liquid/gaseous form. Possibly life forms could be based on plasma, bose einstein condensates or pure energy. All have featured in science fiction. * a distinction between life that evolved and life that was engineered. An engineered life form could be left to go its own way then evolve and/or provolve. By definition machine-life would fall in this category but so could engineered biological (or plasmoid etc) life. Our terrestrial taxonomy appears as a tree because there are as yet no artificial life forms or provolvers. However a universal taxonomy would be a taxonomic phase space defined by a whole bunch of dimensions amongst the most basic of which could be those given above. A taxonomic group is then defined as all species starting within a given volume I (initial) of the phase space, passing through the set of volumes P{} via any pathway and having their evolution/provolution cease ((pro|e)volution ceasing would need to be defined) within volume E (end). Based on the above classification terrestrial life would be seen to have explored a vanishingly tiny fraction of the possibilities defined by the phase space. Having defined a phase space, deploying the tools and terminology of thermodynamic, infodynamics and entropy would then be likely to provide additional insights. We should also be mindful that over the timescales represented the universe is co-evolving quite quickly so this provides another important aspect to roll into the whole framework. Don't ask me to draw a diagram! [Answer] Assuming there actually is life worth categorizing in other places... The problem with the location-based systems is that you're also not including any species that have relocated, or have been relocated. Humans that colonize other systems may result in different evolutionary paths (and recombinations). Same for other older intelligent, space-faring species we encounter. Worse for their equivalent of grain, apples, roses, chickens, cardinals, dogs and cats. That's also discounting UFO DNA complexes, panspermia, etc - which may really muddy the water. Engineered life forms are a problem. As are combination life-forms. When/where/how do you decide that life excludes all metal / AI? Or are robotic self-reproducing systems also needed to be organized under this scheme? A different taxonomy for each original (if it can be determined) evolutionary niche seems plausible, with caveats for things thrown in later, and maybe another layer based on type (eg: uses 2-strand 4-base DNA). We'll probably run fast gene samplers, and morphological search engines to classify new stuff that we encounter, on Earth and beyond. We may even get into cultural diffusion/memetic analysis, as lifeforms learn new methods/behaviors of coping with problems. ]
[Question] [ In the near future on our own planet of Earth, an odd plague has descended from space. It affects glass. Any glass whether natural or man-made turns into powder. The chemical elements are the same, it's just like incredibly finely ground glass. Glassmakers can melt the powder and turn it back into into glass but it just rots away again in a few hours. Scientists are desperately trying to understand the phenomenon, could it be a bacterium that feeds on glass? Not really because the glass isn't chemically changed. They are of course handicapped in their investigations because their light-microscopes no longer have any lenses and lots of their other equipment relies on glass components. Meanwhile the world is falling apart. Missing window glass is forming huge drifts of powder that blow around, ebbing and flowing like a glittering snow. Mirrors have gone but of course vanity is not a priority for most people right now. There are many, many items that contain glass that we used to take for granted in our daily lives. **Question** Assume that scientists aren't going to solve the problem in the next ten or even twenty years. How well would we survive this catastrophe? Could we cope with the glass dust? Would our communications technology grind to a halt? (Think of fibre-optics for example). It's tempting to say, "replace everything with clear plastic". However replacing the world's windows alone would take more than ten years even if it was possible. In any case plastics factories now lack light bulbs, windows, and all sorts of other things that are stopping them from working properly. Assuming the problem doesn't get solved, where would we be in ten or twenty years? REFERENCES **1.** The affected glass is the substance described in the following: > > Glass is an amorphous (non-crystalline) solid which is often > transparent and has widespread practical, technological, and > decorative usage in things like window panes, tableware, and > optoelectronics. The most familiar, and historically the oldest, types > of glass are based on the chemical compound silica (silicon dioxide), > the primary constituent of sand ... A very clear and durable quartz glass can be made from pure silica; the other compounds above are used to improve > the temperature workability[clarification needed] of the product. > <https://en.wikipedia.org/wiki/Glass> > > > ... **2.** What is glass? > > You can make glass by heating ordinary sand (which is mostly made of > silicon dioxide) until it melts and turns into a liquid... sand melts > at the incredibly high temperature of 1700°C (3090°F). > <http://www.explainthatstuff.com/glass.html> > > > ... **3.** Included in glass are natural forms of silica (with impurities): obsidian, lechatelierite, quartz, quartz glass, vitreous silica **4.** ***Real Science***: It's worth noting that, e.g. Obsidian already suffers a very slow type of glass rot before the glass apocalypse. This is the scientist's best lead so far in trying to find a cure. > > *Because obsidian is metastable at the Earth's surface (over time the glass becomes fine-grained mineral crystals), no obsidian has been > found that is older than Cretaceous age. This breakdown of obsidian is > accelerated by the presence of water. > <https://en.wikipedia.org/wiki/Obsidian>* > > > [Answer] We'd survive it. Why? Because H. sapiens made it without having glass for a remarkably long time! However, that doesn't mean it would be pretty. The first thing we would notice is that none of our traditional lights work! The only bulbs I know of that don't have glass in them are LEDs. This would force us to quickly cope with the inability to work at night. Fortunately, we don't have to worry about the fact that all the street lights went out: without glass, car windshields are just flimsy sheets of plastic, so it won't be safe to drive! However, I think we would very rapidly begin making do. Glass, by your definition, is amorphous. Thus clear crystals would support a reasonable portion of the scientific needs for glass. They would not be perfect (every material we use is tuned to meet its goal), but we should be able to at least start peering at the issues of glass rot. Thankfully, I believe the lenses used in photolithography of silicon are not made of glass (fact check?) so at least we'd be able to continue making LEDs. I would expect a sudden interesting period regarding power. It is not immediately clear whether any given material in powerline management is glass (some use ceramic insulators, others use glass). Some equipment has glass windows that are now open to the air. The rapid jury-rigging of the power grid would be a major concern. As a scientist of the age, I would be **very** interested in the state of our fiber optic cables. Those glassy fibers are sealed up tighter than a drum! If they rot, that would give me a remarkable amount of information as to what the cause of glass rot could *not* be. This is especially true for any splices which happen to be undersea (I don't know if we actually have any, but it's theoretically possible). Splices are done with an optically transparent epoxy, so there could be sealed glass fibers thousands of feet under the sea which are fully encased in plastic! Sounds like a source of information to me! *Parting thought: The only thing keeping the lions in their cage at the zoo is glass... oh bother.* [Answer] **How well would we survive this catastrophe?** Initial impact: 1st world countries would be affected the most and have the hardest time at survival because of their reliance on technology/industry. While most computers and servers would not be affected the monitors would disintegrate making using one near impossible. As mentioned, glass in buildings would be destroyed, but there would only be a minor injuries and a few deaths since the glass rot isn't instantaneous: > > [glass] rots away again in a few hours > > > People would probably notice the glass breaking down and most would get to a safe location, or at least move away from windows/buildings. I believe people would remain living at their homes and just cover window spaces with something else (plastic?). In aircraft, there would be some deaths initially but once the rot was discovered I believe most people wouldn't attempt flying a plane in high altitudes (flying should still be possible). Sea vessels would be mostly unaffected. In the long run, many of the technology and science-based jobs would go away. There would be scientists trying to find cause/solution to the rot, but this would only be a small percentage. Currency would probably revert back to hard coin or trading. There would be several million lives lost in this transition probably as most people's life savings would 'disappear' (if it was stored in a bank) and this would cause rioting, looting, etc. Order would still eventually be restored by those with the biggest stick, the military or militias of the countries. Communication would still be up (see 3rd question). Electricity would still be around and there are LED lights. There are thousands of other electronic devices that don't use glass that people would still have access too. Society wouldn't completely collapse, just approach the brink of destruction. 3rd world countries would be affected, but it wouldn't be as extremely life changing for them as those in 1st or 2nd world countries, it might be easier. To note food and clothing will hardly be affected. The only thing that might differ is the distribution of these products. Some rioting and protests. **Could we cope with the glass dust?** Yes, its dust/sand. The glass came from here on earth, and the wind would blow it to wherever wind goes, I don't think there will be a major effort to clean it up. **Would our communications technology grind to a halt?** No. Some communications would break down, but there are plenty of ways to communicate: radio, satellite (unless the rot happens in space), and various forms of cables not made of fibre optics. Then there is the post office (pony express if need be) or communicating face to face. **Assuming the problem doesn't get solved, where would we be in ten or twenty years?** We'd continue technology advancement and probably develop other clear materials to use in place of glass. Computers monitors would be remade, and we'd pick up from where we left off, maybe a couple of decades behind in a few aspects. **Glass alternatives** Minerals: [Fluroite](https://en.wikipedia.org/wiki/Fluorite#Optics) (more of an example that minerals can be used as optics), [quartz](http://geology.com/minerals/quartz.shtml), [plastic](http://www.microscopy-uk.org.uk/mag/artmay07/ms-optical_microscopes.html)(not as good a lense as glass but works) ]
[Question] [ So there is a god. That god has created the world and has almost unlimited power; however he cannot mess with people's minds. So far, so good. However, there's a problem: The god doesn't like it if people worship him. However he even less likes if people worship other gods, even non-existing ones. He'd prefer if all people were atheists. Unfortunately most people in the world are not atheists. And he'd like to change that. But he cannot just turn them atheist because he can't mess with their minds. He can mess with the world, but anything obviously supernatural would be a proof of his existence, and therefore would be counter his goal. On the other hand, just keeping out and let the world go its natural way didn't work out either. He even tried to promote evil (in a way not easily discerned) so people would lose their faith because of all the evil in the world, but even that didn't work out. So what can the god do in order to convince people that he *doesn't* exist? [Answer] Striking down believers with lightning is, obviously, counterproductive: at the least, the Church of Thor Triumphant would get a boost in attendance. The best strategy I can think of is to make the lives of obvious believers miserable, but in ways which can be ascribed to bad luck, rather than divine intervention. Then those claiming public virtue will not be able to claim that their belief has made their lives better. Let the Pope suffer a series of strokes. Let the Dalai Lama contract facial cancer which somehow resists treatment and disfigures him. Multiply this sort of thing as necessary. Call it the Job approach, without the final reconciliation. Even better, since many people (including religious leaders) have public virtue but private failings, the aGod could boost their careers and then, when they gain prominence, arrange for their private sins to be revealed. Think of it as the Jimmy Bakker strategy. A constant succession of discredited religious leaders would probably have some effect. And "he can't mess with their minds. He can mess with the world" allows some really sneaky loopholes. Can the aGod introduce small amounts of alcohol into a person's bloodstream? Being intoxicated is notorious for impairing judgement. How about a few micrograms of LSD or a few milligrams of mescaline? Uncontrollable visions, anyone? If not direct introduction, why not (with godlike stealth) introduce something like LSD into a person's food? A few hundred micrograms is all it takes. This sort of thing would probably be particularly effective when dealing with fundamentalist preachers of all stripes, particularly Christian and Moslem. In the short term it would encourage sects to become more and more bizarre, but with a little luck (and discreet nudges from the aGod) such groups would self-destruct when their craziness goes too far. Call this one (at its extreme) the Jim Jones strategy. Buddhists would be a very hard nut to crack, assuming the aGod doesn't like Buddhists, but that may be just a reflection of my cultural ignorance, and real Buddhists might want to weigh in. [Answer] The best strategy would be to make everything easily explicable by science. Maybe the laws of science would be much more obvious than our own. Instead of having relativity, God could base the universe on Newton's Laws. He could leave a really good fossil record with no missing links. This would encourage people to believe in evolution. If it is too late for the above then God could start giving good luck to atheists and bad luck to believers. Not so much difference as to be noticeable but enough so that atheists tend to positions of power and privilege and can therefore spread their ideas on religion more easily. [Answer] I think you haven't been entirely clear about the requirements. There is a difference between not wanting anyone to *worship* you (as you first stated) and not wanting them to *believe* in you as you said at the end. If you simply want to stop being annoyed by prayers and constant worship then I suggest the following: Regularly strike down with lightning anyone who worships any god. People would still *believe* in god but they wouldn't talk about it or do any annoying *worship*. This would allow the deity some peace and quiet. [Answer] He could 'come down to earth' in a magnificent avatar form, explain and show he's the god they've been worshipping and telling them he is tired, seen it all, and he quits. Strips himself off his powers in a way that ends him up like a normal mortal man, climb a high cliff and jump off in a splat of suicide. That should be pretty clear, straightforward and final, and if there ar STILL people believing in him and praying to him, then at least he isn't bothered by it anymore, since he's dead. ]