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[Question] [ In the land of Wymran live two groups of people: The Schijka and the Joothuns. Both groups are profoundly religious. Their religions have a few things in common: * They are monotheistic * They are each centered around a unique holy book * They all believe in an afterlife * Their religious beliefs tell them to never commit violent crimes * Their entire society is based on religion - they live in theocracies I am a member of a third religious group, the Gurfin, acting as an agent. I want to start a holy war between the two groups so that they will each weaken each other, making it possible for Gurfin to become the major power in the region without actually directly hurting anybody. How can I convince both groups to start a holy war, even though both groups are strictly nonviolent, abhor war, and have not fought anyone since their inceptions? --- **Clarifications from comments:** * The leading figures in each religion are council-like bodies * There is no magic * Each group has about 10,000 people Also, people may be interested in my related question, [Can there be a religious group that will not commit religious violence?](https://worldbuilding.stackexchange.com/questions/20681/can-there-be-a-religious-group-that-will-not-commit-religious-violence). [Answer] There are several methods to accomplish anything and this situation is no exception but all the methods revolve around the same concept. *Dehumanize the opposing faction, make them a threat to your group's way of life and then utilize trickery to get a fight started.* **Methods:** Assumption * The peoples are not hegemonic. Meaning more simply that each individual has his or her own beliefs that range on a scale compared to others of the same faith. This leads to fringe groups, factions and other differences within each religious group. This is important because radicals always seem to exist and in the face of external threat they can drive bad/violent choices. + ***Method one:*** Cloak and dagger violence. + This method is likely the quickest way to instigate conflict but it is also the method most likely to backfire. + In this scenario you attempt to frame each group for atrocities (blow up a hospital or a school or something similar) in turn. Start small, then have the other side retaliate in a slightly more violent fashion and so on until they are at war. + ***Method two:*** The rumor mill and engendering differences + This method is a bit more subtle. Start rumors about one faction and their religion that make it fundamentally opposed to core tenets of the other religion/culture. Start these stories and rumors going on in both nations, nothing will motivate a large group/people to violence like a threat to their way of life. To be most effective it makes sense to use these methods in tandem, starting with method 2 and following on with method 1. * ***Method three:*** The Holy Grail. This one should be pretty obvious. Take an existing super holy artifact, and place it in the lands of the other nation. [Stealing holy artifacts has been known to cause conflict...](https://en.wikipedia.org/wiki/Relic_of_the_tooth_of_the_Buddha) They may be peaceful, but they may also be territorial, but neither has had a reason to intervene before. [Answer] You could go for the same method employed by M in [The League of Extraordinary Gentlemen](https://en.wikipedia.org/wiki/The_League_of_Extraordinary_Gentlemen_%28film%29): disguise yourself as a member of one religion and deface/destroy/steal some relics/artifacts/holy sites of the other religion, then do the reverse for the other religion. Make sure you spread the word that the holy things of one religion are being vandalized by members of the other religion. Just make sure you aren't obvious about it. Leave some people alive to witness the events, rather than running around town shouting it at the top of your lungs. Let others do the work for you and word will spread faster. You'll need to make sure you can make a clean exit after the event. If you get caught during the vandalism or as the result of the following investigation, your plan is ruined (not to mention whatever might befall you). --- Alternatively, you can hire some mercenaries to do the vandalism for you. It would be best to hire people from your own faith, so they have a vested interest in seeing the plan succeed. Mercenaries for hire may reveal the truth if they are caught, thus spoiling your plan, but adherents of your own religion intent on advancing the faith are more likely to keep up the ruse. Of course, involving more people increases the chances of getting caught. If you do hire others to help you or vandalize on your behalf, try keep the number to the minimum needed to carry out the daily or weekly activities. [Answer] I won't be original, but building violence between the two groups on small scale is probably the easiest to go. You probably should follow the following steps: **Stage 1: Insecurity** You need to stage some (apparently random) murders. They have to appear as random as possible, such that people would start to fear for themselves, and be suspicious of each other. You probably should include one or two feat with high impact: horrible killing of a (few) child(ren), for example, to make sure to get everyone's attention. For that you need to get mercenaries, thiefs and killers to do it for you. You might want to impersonate some member of the Joothums while contacting those. In any case you should make sure they cannot link those to the Gurfans. If you can, having economic problem at this stage would help. Issue with supplies, rumours of bad harvest, etc. People are usually more prone to fighting when the economy isn't good. **Stage 2: Religious Motives** While continuing your terror campaign, you should start to attack Schijka's members and offices. But still get on with the murders. The change should not be too obvious. Slowly, the ratio civilian/religious will move towards the religous. The main idea is to make people believe that a criminal group has been formed and that they are targeting the Schijka. Depending on the importance of the Gurfans, you might want to attack your own church as well. If the 3 groups are equally important, you need to do it to let it clear where it comes from. If the Gurfans are a minority, you can spare it. In any case, there should start to have some diplomatic discussions, with some Schijka (together with the Gurfans?) accusing the Joothums of harboring criminals. Due to their pacific nature, the Joothums will run some inquiries to see whether some of their extremists haven't gone crazy. **Stage 3: Rumors and Mass Control** You don't want the inquiries to proceed normally. So by spreading rumours, and placing a few agitators at strategic places, you should get the mob to attack isolated Joothums members. The mob does not have to comprise elements of any religion in particular at first, but as the attack on the churches intensifies, some members of the Schijka will join the revolt. You have now built an insurrection. The main goal of that step is to avoid inquiries done effectively. Furthermore, by implying mobs, you reduces the chances of the elite to control the members of their faith. **Stage 4: Arming the Opponents** You should then proceed to provoke more and more mob furious attacks, on both side. At this stage, it is likely that the lowest members of the churches will get involved. You might need to control yours. Kill all the members of your clergy who might take part in any mob gathering. Whereas you target the most pacific ones on the other churches. To escalade the violence, you need to be able to supply weapons to both sides. That will increase the violence to a state of warfare. Stage mob attacks against the milicia/armies of the religions. You want to set clear objectives. So you can get rumours/speakers that emphasize the differences between the churches, and even set a deshumanization of the members of the opposing church. This will increase the hate and help built something like a nationalism up. A few chocking events on either side would help. "They decapitated a 5-year old girl! They hanged a pregnant woman!" etc. You might consider a staged discovery of the original criminal group at this point. You might get the actual perpretator killed, or not. But you should arrange that members of the Joothums are identified amongst them. **Stage 5: The Spark** At that point, the stage is ready for a fight. The religious groups hate each others, and violent demonstrations are organised by both sides. The time is probably ripe for a good-ol' spark. There are several ways to do that. And you can see what suits the best, from the events and reactions before, but one idea could be to find a few motivated Schijkas, and help them intent to kill an important person from the Joothums church (yes, [Franz-Ferdinand](https://en.wikipedia.org/wiki/Assassination_of_Archduke_Franz_Ferdinand_of_Austria#Town_Hall_reception)). You should help them such that they can really get close to their target, but not really escape, and that they can't link back to you. Whether they kill their target or not, is probably irrelevant. The main idea is to imply the highest members of the churches in what was, up to that point, a base-class insurection. **During the War** If everything goes "well", there should be an open war at that point. But you should not just sit and sip, but you should build your side, with at least the following points * make sure that no member of your church gets involved (from his side), so eliminate the more vindicative and protect the pacific, * continue to supply weapons and some assistance to both side: if they see you as their ally, or neutral but depends on you, they won't try to get you in the civil war, * organise the help to all victims/citizens. You can set up refuges or hospitals run by your Church. At the end of the war, you will be known as the pacific and reliable side. **What do you need to make all this?** There are a few things that should try to do prior to starting, but in particular you should have * a certain control of the economy, * an extensive spy network, * fanatic members of your side, who can be spared later (yes, [SA](https://en.wikipedia.org/wiki/Sturmabteilung)), * financial ressources (weapons, to pay your spy, or corrupt a few people here and there), * little moral and ethic. [Answer] There's **no such thing** as a peaceful religion. Power corrupts. Regardless of whether the founder was a meek hermit preaching withdrawal from the world or a warlord with sword in hand, over the course of decades and centuries, religious figures in a position of authority will invariably self-select to often be power-hungry sociopaths. It's kind of an iron rule of history. Invariably they will attempt to use their religious power for political purposes, including violent ones, unless there is something even more powerful preventing them from doing so. If you tell people that the members of the other religion's mere drawing of breath is a violent crime against the eternal souls of those people, you're pretty much set. [Answer] **Convice both religions that members of the opposite religion are not human.** Both religions may deplore acts of violence, but unless both also promote veganism or the like, they more than likely define acts of violence implicitly as those *against humans*. If you can make people believe that their enemies aren't really people, they can commit atrocious acts of violence more or less unquestionably. I can think of two ways to accomplish this: **1. The other religion's people are witches.** This is probably the easier of the two to make work, especially if Wymran is not technologically advanced. Visit each theocracy posing as a traveler from a distant land. Claim you have recently passed through the other theocracy and were very disturbed by demonic practices you saw there. Find some passages of the other religion's holy book that would sound evil in the theocracy you're in with the right context, or flat out invent passages like "You must sacrifice the children of all non-believers" if the two theocracies are isolated enough from each other that this wouldn't be immediately dismissed. The idea is to plant the seed that the other religion worships a false god, which is really some sort of demon, and they forfeit their souls to him and are then possessed/no longer human. Next, start committing heinous crimes that appear ritualistic, being careful not to get caught. Leave symbols from the other religion everywhere. Whenever possible, use any tricks at your disposal to give the crimes the appearance of a magical element. (These don't have to be incredible violations of physics. Conceal something explosive or flammable in a target's clothing to create the illusion of spontaneous combustion. Carefully drain a victim's blood and replace it with another liquid so their blood appears to have turned green. Even if a rational explanation is available, you should have rigged the circumstances enough that people jump to conclusions.) Before too long things should snowball and you have a Salem Witch Trial situation, only there two opposing authorities on who the witches are, forcing them to settle the issue in battle rather than in court. **2. The other religion's people are aliens.** This one could be fun, but requires certain circumstances. For one, the existence of any significant amount of defectors from one religion to the other over time would be an obstacle. (Not an insurmountable one, but it would complicate things, and runs the risk of causing internal hunts for assimilated members rather than provoking an external conflict.) Secondly, Wymran must be advanced enough that the concept of an alien is widely understood but unsophisticated enough to be fooled by a good hoax, lacking the science to disprove it. Next, fake the discovery of an ancient alien crash or landing site. Include in your discovery a manuscript in an alien language. After a little time has passed, claim to have translated it. Reveal it details the aliens' plan to disguise themselves as humans until their numbers grow large enough to destroy the human race and take over the planet. Ideally, the crash site would be placed between the two theocracies, on the border between them if one exists. The alien manuscript should be kept "secure" (meaning secret), so that you can leak images to both sides mixing alien hieroglyphics with symbols from the other religion to confirm the link in their minds. Once there are alarmists on both sides, fake the test of an alien weapon. Dismantle a secluded structure at night and send up some green smoke at dawn. Investigators will find the place seemed to have disappeared at the molecular level, and the alien hieroglyphics will be left behind. Both sides will think the other side is on the verge of attacking, and when smaller fights occur due to panic, this will only appear more true. [Answer] Expanding on the idea that power corrupts, you only need to look at the history of Earth to see nominally peaceful religions embroiled in violent wars. Perhaps the clearest example is the wars the Samurai undertook against Buddhist monasteries in the Middle Ages. The conflict here was between the Feudalistic Daimyo representing the Shogunate and the Buddhist monks over the nature of Japanese society and who ultimately was to rule. These were not wishy washy monks either. Think of the will and iron self discipline shown by modern day Buddhist monks who choose to set themselves on fire to protest injustices, coupled to knowledge and intense training in martial arts (picked up when it became clear that they were in opposition to the armed forces of the Shogunate, the Daimyo's and their Samurai retainers). Since monasteries were natural fortresses due to their generally inaccessible locations, and the monks had support from the peasantry (think of modern day insurgencies, where the locals support the insurgents willingly or not, to the detriment of the government forces), the wars between the Shogunate and the Buddhists was pretty prolonged and bloody. Since you want a holy war between the various religious factions, that is fairly easy to arrange as well, particularly if the religions are closely related (or even branches of the same religion). Much like family fights are often bitter and all consuming, religious quarrels over interpretations of elements of doctrine can also become quite violent and prolonged. The Catholic Church's first crusade wasn't against the Muslims in the Holy land, but rather the Albigensian Crusade (1209-1229) against "heretical" Christians in southern France. The 30 Years War destroyed the population and infrastructure of much of central Europe, over the question of should people and Princes worship in the Protestant manner or the Catholic one? The current wars in the Middle East pit the Salafist Sunni ISIS against the Shi'ite Persians of Iran as the major players, but even when ISIS burns out or is destroyed, the Shi'ites and Sunni's see each other as apostates to be destroyed. So the power of religion to mobilize the minds and spirits of men can be channeled into surprising things: the same drive that builds monuments and cathedrals also drives armies of conquest. [Answer] One point that several other people have mentioned is human nature. regardless of if you believe in a religion it would be foolish to deny the corrupting influence of power. This has manifested through history in the fact that often the leaders of a religion are often not the best examples of its tenets. Also, while the entire population of both sides may be peaceful, the leaders are corrupt enough to be manipulated. Also, their position gives them the authority needed to cause trouble. So the plan could be this. 1) pursue the course of action other answeres have outlined, i.e., stirring up hate/conflict. 2) find a good reason - or one that sounds good - for conflict that is not religious in nature and make sure that those in power are aware of it 3) This may not be possible but if you can convince those in power that they are in *personal* danger there it much more chance of something happening 4) while all this is going on you must try to strengthen the legitimacy of the leaders, so that the population, stirred up against the other religion, is ready to follow orders that they may have misgivings about. 5) knock of anyone who tries to raise theological arguments to the actions of the leaders. This way you play on the strength of people's belief, rather than just on their capacity for hatred. Seems like it would be more effective. [Answer] * Go to some random place of the planet * Draw a large enough square on the ground * Pick 2 random folks with different religion * Tell each of them that this land is theirs * Let events unfold Sure enough, there will be war. Will they make it an holy war? Maybe yes, maybe no. Anyway, it will help your scheme all the same ]
[Question] [ So, a setting I'm brainstorming is basically a tribal world, with Hunter-gatherers, animism, and the like. One of the features I want to add, to make it stand out from our own world is the existence of megaflora, like giant trees, or fruits the size of houses. Like, instead of growing a bunch of normal sized crops, you can grow one or two mega crops to feed the whole tribe. Also, this just came to me, but I could see religion playing a role where the tribe tries to please the spirits so that some plants will grow to giant size. If the spirits are angered, the plant doesn't grow or fails to reach that size. I'm not familiar with the average size of IRL tribes, but the average size for a tribe in this setting is a couple thousand people. They are baseline humans. The plants can sustain them for the same amount of type that an entire harvest of normal crops can. There is magic in the setting, but so far it's very barebones, so I need to figure out how much of an impact it has on megaflora, if any. The practitioners of magic are known as shamans, and they serve as mediums between the human world and the spiritual realm, and specialize in healing. This led to me trying to think through the implications of such plants. Could plants that big sustain a village or tribe sized population? [Answer] Your biggest problem is not nutritional value. It's that with big food items you need to eat them over time and it's hard to keep them edible. I have a very large species of breadfruit, and my locale has some huge bananas (forearm width and length). Even with my six kids we can only just manage to eat one breadfruit at a sitting, and with the bananas there is no way we could manage a bunch (you don't just pull off one banana). So scale that up several times and you have a lot of rotten food messing up your area which is inefficient use of resources at best. It could be done of course, but the food processing would be pretty intensive and time consuming. Everything from transporting the food to processing it for cooking and disposing of waste products would be a group effort. We could roll a mango to feed ten people with, but what do we do with the stone the size of a beach ball? Or 20 apple seeds the size of my head? [Answer] In a certain way, we've done this with some plants in the real world. Go into Google and look for images of "Alaska Pumpkin". Those can grow to weight up to a ton, sometimes more. And I believe they are just as tasty as regular ones. Going a stretch further, bananas. Yes, bananas. No, you won't see a giant phallic fruit anytime soon, but we've inbred wild bananas so much to make the modern varieties that the plant no longer breeds through fruits. In any banana field that is allowed to propagate by itself, each trees produces new trees as ofshoots of itself that stay connected - basically a whole forrest may be a single individual. The fruits will still be regular-banana sized. And finally there are cashews, baobabs, and sequoia. Alright, the latter is not known for being edible, but imagine your people learn to extract syrup from sequoia sap. Baobabs aren't as tall as sequoia but they can be so wide that some dude in Africa carved a bar inside one. They only give fruit very rarely and it's not edible, but you can imagine a world where they would give apples or something. And as for cashews, the nut itself may be tiny, but the tree is mighty. Here is a picture of the largest one in the world: [![The Pirangi Cashew Tree](https://i.stack.imgur.com/cE8tl.jpg)](https://i.stack.imgur.com/cE8tl.jpg) You may be wondering where in the picture the tree is, and you may probably think it's within that city-block sized park by the middle of the photo. That whole park is the tree. And no, that's not a tree that cloned itself through offshoots like bananas do. That whole thing has a single trunk. It's just that when the branches become so heavy that they touch the ground, they make a pseudo-root and then continue growing up. Regular cashews are not that big... Some people reckon the big one in the photo occupies the area of 70 regular sized cashew trees. But I can tell you even one alone is gigantic. I married under a rather big one (and rather taller than the norm), and it basically shaded the 2-story house which had the lawn it was on, as well as a neighbouring house. And cashew trees are fruitful. You can harvest up to 9 tons/ha yearly (not just the nuts... the accessory fruit where nuts hang from is edible too, and it's delicious and sweet). Compare with 4.1 tons of corn or 2.3 tons of wheat for the same area, and you see that by square footage cashews will make your population diabetic much faster. [Answer] Normal flora was already, in many historical cases, sustaining whole communities: potatoes and cereals are the most notable examples. It's not far fetched to imagine that, instead of growing hundreds of let's say potato plants, a village could survive by growing a single, giant plant producing the equivalent harvest of those plants, either wit a single, enormous produce, or with several, smaller ones. However don't forget that this creates an additional risk: growing a single plant makes the consequences of a failure in the growth way worse than growing several smaller plants. [Answer] There are numerous science fiction instances where a megaflora provides an entire ecology for a society. Kevin Anderson's *Saga of the Seven Suns* has the Therons. *The Integral Trees* is an archetypical example. If science fiction can do it, it wouldn't take much magic. I think you underestimate the amount of plant matter that a mega-flora could provide. The largest plant on Earth -- the largest creature on Earth -- is 200 square kilometers of seagrass (yes, one single plant). If you want a tree, we could talk about the [Pando](https://en.wikipedia.org/wiki/Pando_(tree)) quaking aspen, which is 106 acres of just one tree. If you're looking for a mono-trunk, as with the giant sequoia, then you might want to consider that trees are very much like coral in that they are a relatively thin layer of biologically active tissue, in this case growing on the lignin scaffolding left from previous cell divisions. You could build a mountain that way. In reality, the [Acacia tree](https://omnia.sas.upenn.edu/story/mutualistic-relationship-between-ants-and-acacias) provides a fascinating example of mutual specialization. The plant feeds and houses ants (pseudomyrmex ferruginea) in return for the defense the ants provide. The real question you'd have to answer would be whether that one plant type was nutritionally complete. It wouldn't be impossible, but it would create people who are symbiotic (or parasitic) to the plant, and probably fully dependent upon it. For humans, it would be more likely that we would also eat the creatures that find their homes in the megaflora. [Answer] **Yes... and No** * If you can't eat it fast enough, the plant rots — and rotting plants bring stink and insect infestations. * Some plants can be dried for long-term storage, some can't. * The practical difference between one mega-plant and the bushels of "normal" sized plants is that it's easy to pick up a single "normal" sized planet and much harder to do so with the mega-version. In other words, the megafauna are more difficult to manipulate. * If you have an orchard or a field and a few trees or plants die from something like fire blight, you have the rest of the crop to work with. If that happens to the one or two megafauna plants your tribe is relying on, they're all dead of starvation. One big object is rarely better than many small objects. * I'm assuming we're not talking about a single, giant grain of wheat, but either large leafy plants (most believable) or large fruit (less believable). Fruit has a lot of water in it, and where there's water, rot comes more quickly and drying is more difficult. As I ramble through this answer, the water content of the foodstuff is one of the more important aspects of your worldbuilding. The higher the water content, the less believable the solution. ***However...*** We're assuming from your use of the word "crops" and the tribal size of several thousand that your tribe is stationary. Maybe that's where you need to make some adjustments. It would be trivial to rationalize feeding an entire *nomadic* tribe off of megafauna. That's little different than the American Natives harvesting buffalo, one or two of which could feed an entire family for a year. Less so a stationary community that depends more on predictability and the ability to stockpile. It also depends on what you mean by "megafauna." If what you mean is strawberries the size of my fist, then this is really a non-issue as there would be little practical impact on the nature of harvest and storage (might not be enough chocolate, though...). However, if we're talking about strawberries the size of a house, then everything I've pointed out comes into play in spades. Therefore, I see that your worldbuilding has two dials to play with: produce size and water content. As either increases, the believability of the solution decreases. [Answer] It's a long time since I read [The Future Eaters](https://www.reveriebooksellers.co.nz/p/the-future-eaters-an-ecological-history-of-the-australasian-lands-and-people), but, as I recall, people learn about the environment by screwing up: more importantly, they realize they screwed up, and put measures in place to stop things getting worse. The ancestors of the Aborigines made it to Australia, ate the megafauna, then realized that they had brought about a food crisis. Tim Flannery argued that many Aboriginal customs had the effect of preventing the extinction of the remaining food species (establishing effective refuges, for instance). Can you build this idea into your story? Could your natives have realized earlier that they were heading for a catastrophe, and prevented it? [Answer] At the most basic level, whether the megaflora can sustain the tribe depends entirely on whether the energy it converts into fruit, roots or otherwise edible parts is enough to sustain the tribe. The energy a giant plant has available for that depends (if magic does not help) on how much sunlight it can take in. You might be able to guess where this is going - yes, giant plants that cover three square kilometers (or whatever area) with their leaves will have the same amount of energy available as many small plants covering three square kilometers (or whatever area). They might require more of it for their non-edible parts, or maybe even less after the initial growing time, that is up to you. But at the core, if the area the plants cover is as large as the area of farmland you'd expect to need to feed your tribe with normal-sized plants, it can work. Practical concerns exist, of course. Others have brought up harvesting and processing of giant fruits (or mining them while they're still on the plant, hopefully without inviting too much rot). Then there's the growing time - if your magic does not intervene, a huge plant will take a lot longer to grow than many small ones. And the same is true for fruit - it will be hard to deposit all the sugar and water and whatnot for a three-story pear in place during a single summer. So the tribe might be watching a megapear grow for several years, looking forward to when the shaman finally says "yes, it is ripe. Let us begin the harvest." The growing fruit might have to be defended from (normal or huge) pests, mold, other fungus, hail, frost... this can shape the culture of your tribe a lot. And let's hope there either is no megafauna or the tribe knows how to hide the fruits they're protecting from them. That might be a whole other story hook! ]
[Question] [ Let’s say there was an early alien civilization, not yet advanced. They hail from a planet with little to no oxygen. If this planet had electrical storms relatively frequently, could they harness the power of electrical energy before the thermal energy of fire? [Answer] **Probably not** The problem with electricity is that to "harness" it you need something to conduct it. Traditionally, that's wire. And the problem with wire is that you need metallurgy. And you can't use electricity to perform metallurgy without having the metallurgy first to get wires to conduct the electricity (you know, did Adam have a belly button? kind of problems). And the problem with metallurgy is that it needs heat. And heat needs either fire or electricity. Well, or chemistry. Maybe that's a path to success? Your people discovered a chemical means of creating heat before they discovered the ability to harness fire? But that's stretching credulity because your lightning strikes are *causing* fire. Long before your people understood that the bright flashy thing in the sky could be used productively they'll be running from the bright hot stuff it leaves behind. And it's hard to believe they wouldn't look at that hot stuff first and think to themselves, "I wonder what the pig I just killed would taste like if I used a bit of that bright, hot stuff?" **But your planet has little to no free oxygen** And that means there's no fire left behind by the lightning. But there might be a problem with lightning, too. In the worst case, lightning in a vacuum isn't visible. There's nothing there to ionize to create light. Oxygen is an obvious light creator because of the tragic [Apollo 1 incident](https://nssdc.gsfc.nasa.gov/planetary/lunar/apollo1info.html). But we live in an atmosphere with 78% nitrogen and 21% oxygen. If your atmosphere has little or no oxygen (no open flames!), what's taking its place? Let's assume it's mostly nitrogen. Check this out ([Source](https://en.wikipedia.org/wiki/Ionized-air_glow)): [![enter image description here](https://i.stack.imgur.com/GnMnCm.jpg)](https://i.stack.imgur.com/GnMnC.jpg) That's ionized nitrogen (kinda what your lightning would look like! Cool, am I right?). Compare that to the more familiar ionized oxygen... [![enter image description here](https://i.stack.imgur.com/HfIoDm.jpg)](https://i.stack.imgur.com/HfIoD.jpg) But I might be digressing. Nope, I'm digressing. As cool as lightning in a nearly all-nitrogen atmosphere would be, the reality is that you need a way to conduct it. Yes, salt water... graphite... but my problem all comes back to the need for heat in fundamental technologies that are required to harness lightning. If you think about it, you need heat just to make durable clay pots. Can't do that using lightning without conductors. And I can't think of any conductors that don't require heat to manufacture them (I'm pretty sure you can't make a Van de Graaff generator with salt water. Maybe if you had plastic or glass tubing... Argh! Need heat!). *So your real problem is how to get heat without fire so you can harness electricity.* **TL;DR** Yes! You can do it, but only if you discover acids or other exothermic chemical reactions so you can develop metallurgy. Heat, my friend. All technology begins with heat. [Answer] ## They can develop some crude uses of lightning, but no more than that (and the aliens themselves may not even be possible...) There are a number of issues to untangle here, but they mostly boil down to "exothermic oxidising reactions (fire) are ***really*** fundamental reactions." I'll start with what should be possible: ## The aliens can use lightning rods to get lightning to strike in a convenient place It won't take long for them to realise that the flashy dangerous stuff tends to hit tall things first. Sooner or later, someone is going to try putting up a stick to get the lightning to hit it (based on what we know about earth-based intelligent life, this will either be a dare or to impress a female - likely both at the same time). Some time later, someone will start putting the other end of the stick somewhere it does something useful. Applications I can see for this are heat (a corner of the cave that gets repeatedly struck by lightning could make a decent campfire substitute, even if it is going to be... exciting trying to cook safely there) and some form of electro-fishing or hunting. Cause a deliberate lightning strike in a river or over a xenorabbit burrow, wait for the fireworks to end, then collect your new precooked meals. Pushing this too far means finding a good material for your lightning rods, though, which runs into the second issue: ## Harnessing electricity in any major way means conductors, which means metal, which means smelting, which is really hard to separate from fire Others have already mentioned that getting metals without heat is difficult, but there's a second layer to this as well. A lot of ores (and particularly the ones that are useful for a bronze- or iron-age-equivalent tech level) are oxides - that is, a combination of metal and oxygen atoms. Freeing the pure metal requires persuading the oxygen to go elsewhere, which essentially means getting it to react with something else instead (usually some form of carbon, and often carbon monoxide - which is easiest to produce using fire). For ores that *aren't* oxides, one of the primary processing methods is 'turn them *into* an oxide, then proceed as above. This process can be summed up as "utilising a controlled fuel-and-oxygen reaction" - and it's really hard to come up with definitions such that 'these creatures have mastered controlled fuel-and-oxygen reactions' and 'these creatures have *not* mastered fire' can both be true simultaneously. Incidentally, harnessing electricity probably also means batteries, which again mostly involve metals somewhere (see above). There are some potential alternative chemical pathways here, if you wanted to substitute in chlorine or fluorine (or maybe even sulphur) chemistry for the oxygen - but that's why I said 'exothermic oxidising reaction' above as my definition of 'fire'. At the end of the day, it's going to be really hard (probably impossible) to find a realistic set of reactions that your aliens can use that doesn't have a version of 'fire' in there somewhere, even if it's a fluorine-metal fire instead of an oxygen-carbon one. Which leads to the third question: ## If your planet's environment doesn't support some kind of fire, it probably doesn't support intelligent life either Humans, as well as basically all other non-photosynthesising life on earth, can be thought of as a ***really sophisticated*** form of fire - at least 'from a certain point of view'. The reason I say that is that all of that life is powered by those same exothermic oxidising reactions I keep talking about. If you want life, it needs an energy source. Photosynthesis is one, but it's low-output - there's a reason that plants just sit in one place and soak up the sun and all *active* species are using another energy source. So for another energy source, we need some pair or set of substances that will react to produce an energy output - and there needs to be a substantial surplus energy over what is used to keep the reaction going, since that surplus is what powers the organism. So if that's true, then we should be able to *also* bring those substances together and react them outside the organism - and 'chemical reaction that produces a substantial energy surplus' is awfully close to 'fire'. The only one I can think of that might not qualify is something like a metal-acid reaction carried out entirely under the surface of a liquid - and even then, there's a reason we talk about acid *burns*... [Answer] It depends on what is meant by "discover". 1. **Detect?** On a planet with a lot of storms, this is not a problem. 2. **Use and create by yourself?** There are many creatures on our planet that can generate electricity on their own. 3. **Assume its origin?** In ancient Greece, it was assumed that all matter consists of small particles, atoms, long before they were discovered. 4. **Understanding of its origin?** If we talk about understanding the origin of electricity, then we can say with confidence that the fire was discovered in the XVIII century. (discovery of oxygen and combustion reaction) Now in history, the discovery of fire by mankind is understood as its first creation by man on his own, at his own request. Therefore, I think that question and answer 2) is the most correct. [Answer] You don't need to get rid of all the oxygen to make it hard or impossible to start fires. So in response to some of the challenges of having no oxygen, perhaps the percentage of oxygen is low. On earth for example below about 16% oxygen you typically won't have a flame. But that might be sufficient for many forms of life. Without fire - there could still be ingots of some metals gold for example that might be very precious, iron from meteors, but metals might not be unknown. Less corrosion and rust is probably a plus. As a stretch perhaps there are geothermal sources of heat that could be used as furnaces. There could be a greater dependence on organic chemistries, growing or shaping materials by grinding. A lithic society where obsidian and flint/chert tools are much more common. Discovering how to make glass is tough without a source of heat, and air dried pottery is not strong. But if other chemistry technologies are developed, tree saps resins, natural rubbers perhaps hard pottery as we know it wouldn't be around, but bladders, skins other storage might be more common. It takes effort to shape stone, but depending on the geology some stones can be ground to high precision. Discovering electricity might be inspired by trying to understand the frequent lightning storms, by noticing the sparking when you rub dissimilar materials together- also leading to the discovery of insulating and conducting materials. One can make electrostatic motors or generators. Discovering batteries would still be very reasonable. The comment about graphite and carbon being conductive gives another type of condutor to work with. With out fire to make charcoal, maybe natural coal and graphite are more important as conductors instead of as fuel, until they discover how to increase the percentage of oxygen, then that might be a big surprise when things start burning easily. But at some point they may discover oxygen can make things burn easily, which would be a big innovation. [Answer] It can but you will have to cheat, somewhat. Give your people an organ that will create electricity like electric eel. This means they means they have a tame way of creating electricity at will. As they get smarter, they will find different uses for their electricity generation. There are different materials that conduct electricity, especially if the voltage is high enough. After they pass a certain threshold in intellectual capacity, they might wonder if they could harness what looks like supercharged version of their zappy powers. They might think, if we can get it to this place, we can heat up tons of water instead of grams of it or heat their entire home instead of their palms. Obviously, it might be possible for them to learn about fire earlier than they tame lightning but even with that, the first form of energy they control will be electrical rather than heat. [Answer] **Maybe. Seems most Unlikely.** Electicity needs conductors, which are normally metals. Metals aren't found lying around in oxygenated atmospheres. To extract them from their ores, benerally requires fire. (Gold and copper are known in native form as minerals, but aren't abundant). However, we know life existed on Earth before photosynthesis evolved (and when it did, life almost made itself extinct -- the great Oxygenation catastrophe). So, could anaerobic life take a different path to harvesting solar energy, that maintained a reducing atmosphere? In that environment, metals might easily be formed by biology. (It's believed that most if not all native Gold and Copper arises by the action of anaerobic bacteria here on Earth -- or rather, miles below the Earth). We know very little about abiogenesis, and what other forms of life might be possible. Speculating wildly, maybe a world where as anaerobic life evolved to become multicellular, its equivalent of nerves was actually very fine filaments of a metal. Copper, perhaps. Insulated by a nonconductive biopolymer. Wires! Perhaps the intelligent life that arises doesn't need to discover electricity as something non-biological, because their biology is more fundamentally electrical than ours? Or even, that evolution there used biological gunk as a stepping stone to bootstrap something that looks more like micro-electronics than life as we know it, even before intelligence arises? Unlikely does not mean impossible. And in an infinite universe(?) anything that is not impossible by definition, *will* happen. [Answer] MAAAAYBE? If the creatures just need to "get off the ground" with tool making, and some metallurgy to harness lightning. perhaps they could use geothermal to get to at least pottery? pottery/ceramics you can get some chemistry going. some metallurgy. Slow but steady. As the OP said the race was seeded from a more advanced race. Maybe they left behind a touch stone, sort of a cookbook or encyclopedia how to surpass the fire barrier. Or just plain creativity, some metallurgy might be possible with a relatively calm extrusive basalt type eruptions from volcanoes. Bonus, relatively pure unoxidized ores should be plentiful since there is no O2. [Answer] Cadence said it above. Lots of free flowing imagining goes on that is a thought exercise, but these kind of questions should be addressed based on what we know about evolution on this planet since it is our only certain set of facts. Understanding the formative power of habitats on earth is a logical approach to hypothesizing how something could evolve on another planet. How genetically unrelated organisms have evolved similar adaptations to similar environmental conditions on earth is a power lesson. If you start with a limiting condition like lack of oxygen on another world, and that is all you are given, and going on imagining complex beings with technology, in itself is quite a leap. [Answer] # Discover electricity for what benefit and up to which level of mastery? Today's usage of electricity (lighting, heating, cooling, appliances and computers)\* but at what stage would your civilisation be? ## Basic Heat Afterall it is often considered that humans controlled fires which were a side effects of lighting setting organic matter on fire after storms. Here we need to assume beyond the low oxygen level (or any other local reason which prevents fire from being possible), we'd need something which helps funnel lighting energy. One way analogous to circuit protection would be to have a PTC which would offer low resistance for lighting at first but then would heat up and keep the heat as electricity cannot flow somewhere else. So could you store heat, electricity would have to flow through either a material or a plant that would have a positive temperature coefficient: something that increases resistance with temperature and surrounded with highly isolating material. The trees could be of this sort while maybe the ground surface grass could be highly isolating. So once stroke by lighting the trees would warm-up and if with a high thermal mass they could do the job (of course they could not be made of cellulose like trees on Earth) ## Electricity storage The fruit of those trees could be similar to leyden jars and be charged to high-level once stroke by lighting and the stem of those fruit being say the positive and the skin the negative of those batteries ## Electricity Distribution without wires Neurons can carry electricity and could be used for interconnecting entities. Instead of calamars which were used for studying neurons at first and are rather rare on land, make one of the most prolific animals of your planet one with extremly long and hardy neurons, easy to harvest. Next could be to weave them in for ever bigger wires, maybe your civilisation could find a spider with instead of high mechanical resistance (like on Earth) spins with a fibre with low electrical resistance. Weaving those together could give you wires for engines and then for machines. ## Electricity for machines and Appliances One a strong enough capacity for electricity distribution is available (wires of neurones or spider-like silk) building machines can be made fairly analogous to Earth. ## Electricity for Computers Making chips without having developped metalurgy might be difficult but maybe your civilisation could skip the transistor and start straight at the artificial neuron stage... \* > > People use electricity for lighting, heating, cooling, and refrigeration and for operating appliances, computers, electronics, machinery, and public transportation systems. Total U.S. electricity consumption in 2021 was about 3.93 trillion kWh and 13 times greater than electricity use in 1950.` as per [EIA web site](https://www.eia.gov/energyexplained/electricity/use-of-electricity.php#:%7E:text=People%20use%20electricity%20for%20lighting,than%20electricity%20use%20in%201950.) > > > ]
[Question] [ # Background This is a sci-fi setting. People there have advanced biotechnologies, being able to edit the genetic code of embryos (governmentally enforced to be strictly regulated and only for medical purposes as like curing some genetic disease), and a range of tech that allows them to grow organs in a vat (Mainly used for artificial meat production). # My question is: While the technology allows for growing limbs and organs to replace those that were lost due to accidents, why do many in the setting still prefer to fix themselves with cybernetic augmentations rather than grow a new leg in a vat? # Additional Notes Those cyber limbs are *not* of a Hollywood variety, and while can be better than their organic counterparts, require some maintenance and do not grant superhero abilities. No, you can't punch through a concrete wall or lift a car with one, but you can have fingers that have micron-level precision and can bend backward, for example. [Answer] The answer is there in the question: Micron-level precision of fingertips isn't something you get from meat. Biologics have a superior user experience/look & feel. There are likely some things that will never be replaced with hardware. But hardware has a number of advantages over squishware: 1. Consistency - Biologics are notoriously dynamic things (evolution only works because of this). While they're able to actively maintain themselves, they're also notoriously susceptible to environmental conditions, infectious agents, and other threat vectors that you can't ever truly escape as long as you're building with meat. Hardware has to worry about corrosion and erosion... and that's basically it. Sure, I could get my arm replaced with meat, but odds are I'd end up needing to do that more than once. If I don't care about the aesthetics, maybe I just want a piece of polymer with some carbon-fiber 'bones' to it so I can set it and forget it? That micron-level precision sounds great if I'm an artist designing sculptures at the microscopic level. When we're able to replace virtually anything with either meat or machine, then the body becomes a tool and we upgrade it according to the demands of use. 2. Aesthetics - Maybe I *do* care about how it looks? Maybe I've got ideological problems with foreign meat being attached to my meat? Maybe I think everyone who's using biologics "because it feels natural" is kidding themselves and I want to be punk about it? Maybe I grew up idolizing Darth Vader? 3. There are a few places where machines simply are superior to meat, most of them involve hazardous environments or dangerous jobs. 4. Finally, it's entirely possible that artificial organs and limbs have to be specifically tailored to my body/genetics. That could be expensive, whereas mechanicals are basically an off-the-shelf solution. There's PLENTY of room for juicy classism there. [Answer] My own take is based mainly on adding plausible issues to the bio-side of the equation: ## Growth time You can't just assemble a new complex organ or limb that has all the blood vessels, ligaments, bones, and muscles in it. Those things require being grown naturally, and you can't rush that process too much, so a new limb can take up to several years to become fully mature for transplantation. Cyberlimb can be installed on the same week the accident happened. ## Accidents during production The growing process is long and can have a number of accidents that ruin it (it spontaneously gets a cancer tumor, slight hiccup of the supply of the nutrients or error in genetics causes it to grow deformed, an infection finds its way into the vat, etc), in which case you have no choice but to scrap it and begin from a single cell again. ## Immune system response The body's immune system can still reject the new limb, because it was grown from a tampered DNA that was changed for it to grow to adult size in a couple of years instead of a couple of decades. ## Rehabilitation process Regaining control of your new limb requires lengthy rehab that can span anything from months to years, just like it does in real life, and might never become fully complete. Cyberaugs, in contrast, are controlled via a self-learning brain-interface implant, that takes only several weeks to adapt to the neural patterns of the user, and after that can function with any cyberlimb model that has compatible control I\O protocols. [Answer] ## Mechanical is simply better Biology is in many ways incredibly efficient and perfect. Yet there are limitations on what you can do in structural or muscle strength. In contrast, any mechanical part can have far better limits, be purpose build, have more features and can potentially be replaced in a very short while. Now the question is, why not? We see that in our daily lives efficiency is only so so important for us. Many examples can be shown, like lots of the personal transport business, where we definitely aren't efficient. So if you offer someone a mechanical upgrade that is stronger and better in every way, but power hungry. Will they say yes? If power is abundant, *why not?* And again, you have a ton of potential options. As an (unlikely) example, a smith with fireproof hands might have the power together with the feel to incredibly accurately finish some details on a red hot glowing piece of metal. Integrated plasma torches, a light, different optical usages on a whim and so much more. With genetics, a little imagination and some sci-fi you can go a long way, but never as far or as quickly as with mechanical upgrades. Besides, if you need to wait a month before you have your arm back or have it immediately (with possibly a month of revalidation ironically) many would choose instant gratification. [Answer] **Why not be both?** The flesh is weak, but steel is cold. Biological material is susceptible to many environmental conditions that robotics are not. It takes time to develop, to grow and heal. Robotics is strong, resilient, reliable and can be repaired quickly. However, biological components have certain properties that would be beneficial, such as the ability to have sensation and the ability to communicate with the brain. You can have a full robotic body, but it may be beneficial to have biotech/mechanical interface components to allow control over the body. biological components are also harder to hack than a artificial system. You can also have synthetic biologics, basically biotech growing mechanical components that simulate how the body works, such as synthetic muscles or circulatory system. You could substitute more robust materials in place of natural, such as silicone coolant/hydraulic (blood vessels) and nano-fiber actuators (muscle tissue). Cybernetics could also give sensory advantages that just does not occur in nature, such as telescopic vision in multiple wavelengths, audio magnification and detection of energy such as radiowaves. Biology has created perfect systems. Robotics can make such systems beyond perfect. [Answer] **No time** The best artificial limb is yours, biologically your genes. It should just grow back, to fit you. But the inhabitants of your planet have busy jobs, they don't have time to wait for slow biology. The growing needs medication, takes months.. they just buy a metal limb that fits, works and looks good. **Avoid medical procedures** Many people prefer contact lenses instead of a laser operation: you may choose to get your eye *lasered* in a hospital, or you can just order a box of 50 lenses online and put in a new lens (a prosthetic) in the morning. Same with good quality metal prosthetics on your planet: some will have the money to buy a metal prosthetic for a few months and meanwhile grow their bio-replacement limb in a reactor. This technology can breed a perfect prosthetic limb, in due time. But the result would have to be *stitched*, using classical medical procedures. Also, intense revalidation procedures are needed. On your planet, engineering and smart sensor control is preferred over complications and therapy ! [Answer] # Competition: Your Futurians live in a world where there are lots of pressures to live in new environments. The same laws preventing bio-enhancement also forbid the governments of the world to use mandatory birth control. Because of cheap biological parts, no one dies, no one is infertile, and custom-made organisms and machines do all the work people do. The population grows and grows, while opportunities to advance shrink and shrink. 95% of the world's population is on the dole. Biological bodies are also poorly interfaced with machinery and virtual environments. To get a really convincing virtual experience, you need microchips implanted in your skull/brain/sensory tissues so you can experience convincing virtual realty. Trust me, with population pressures and overcrowding, you WANT to escape reality. And the jacked up have a competitive advantage over those who aren't. Maintaining a full-scale biological body in the deep ocean or deep space is resource-intensive. But machine parts are able to tolerate high or low pressures and temperatures. So if you aren't fantastically rich, if you want to live in something better than a tin can in an overpopulated city, it's time to get the cyborg conversion. Sure, you are basically a brain with life support in a can. But if you want kids, those parts are kept in a storage facility. And companies WANT people who can swap limbs, interface with space shuttles, or go out in mini-subs the size of a normal human, because they are basically a dedicated cyborg body. The company gives you a chance to get ahead, and if you get rich enough, you can simply grow a new biological body and retire to someplace nice. [Answer] As I'm surprised that no-one has mentioned either of these as main factors yet: ## Cost Growing things in vats takes time and costs money. Detailed surgical procedures to attach new limbs and organs correctly requires money. Even once things are attached, you will need regular check ups from a skilled doctor and probably physio-therapy as well for appendages which again costs money. Spending all this time doing that will make a dent in your regular work pattern i.e. indirectly costing you money again. Any slip-ups in the procedure may cause you to have to go back to the start of the process and try again. For prosthetics, they need little, if any, customisation, roll off a factory production line so can be purchased "off the shelf" and are essentially plug and pray. Yes, you might need a doctor of some kind to hook you up but once that's done, the rest is just an occasional lube and re-charge/refuel. ## Regulation > > governmentally enforced to be strictly regulated and only for medical purposes as like curing some genetic disease > > > Although the question states that is for embryo editing, let's think realistically. If I want a new organic arm, do I want the same one as I had before or do I want one that is genetically tweaked to build more muscle mass? How about one that's less hairy or a slightly different skin tone? Maybe I fancy an extra finger? Perhaps an extra joint? Maybe two arms linked to the same shoulder joint? Finger-tips that glow in the dark? Bear in mind that people have the ability to grow meat in a vat. It's quite possible that people have such a vat in their homes, so they can harvest meat at their convenience, much like people grow their own herbs or vegetables today. By having this technology available in the home, it won't be too long before some bright spark realises that with a little reprogramming, you can use a home meat vat to create other items by changing the DNA seeding. As soon as people start to get creative, what began as a little vanity for some and a bit of practicality for others will soon be abused before too long and that will result in government regulations as well. Initially a little regulation to ensure basic safety is a good idea but once people start using non-regulated parts to get around this, the level of regulation will become increasingly heavy-handed. Imagine that the trade in non-regulated parts gets so bad that the regulations state any replacement body parts have to be an absolute minimum of 99.8% identical to the part it replaced and your genetic code. Failure to comply results in the replacement part being removed on the spot without anesthetic, a lifelong ban on organic parts and a hefty fine. Given that organic body parts can age and deteriorate, this would soon render the replacement body part market an extreme luxury as finding production facilities good enough to ensure regulation compliance for the expected lifespan of the replacement body part will become increasingly challenging and you will have to pay accordingly. Prosthetics, on the other hand, are simpler to regulate as they can only be produced by licensed factories. The power source/actuator/processor/neural connector from prosthetics gives off a signature that is really easy to trace and any third party tampering will change the signature from the factory one. ## Conclusion Essentially, it's cheaper, faster and less risky to get kitted out with prosthetics, so that's where the money goes. Once portable body scanners start to be issued to undercover police agents as part of the crack-down on non-regulated organic body parts, the above becomes even more true and everybody who gets caught out once will be on prosthetics for life. [Answer] **In a country with free vaccines, why do so many people choose not to get vaccines and perpetuate a global pandemic?** **In a country with a readily available supply of insulin to manage diabetes, why do so many people ration insulin, or die from lack of insulin?** **In a country with billions of pounds of food wasted every year, why do so many people starve to death?** **In a world with genetically modified crops that produce 10x the yield, why do countries reject those crops and allow their people to starve trying to grow "traditional" crops?** As you can see, people and societies do not always (do not often?) behave in rational ways. People do not have the means to access certain resources because those more greedy and powerful than them decided to hoard and/or destroy those resources for their own gain. People live in societies awash with propaganda. People are prejudiced against technologies that they don't understand, making them even more susceptible to propaganda against those technologies. The real question is not, "Why do people use mechanical prosthetics when bio-replacements are available?" The question is, "What rich segment of society benefits from most people using mechanical prosthetics instead of bio-replacements, and how are they using propaganda to exploit the masses?" [Answer] # Rejection of new limbs. New organs often have some rejection issues, because they have minor differences from the original organs. This requires a geneticist to work on them and fix them, or reclone the limb. It's certainly doable, and in the short run it's fine, but it's not an easy or a quick process. This drives the price up, and the time to make such organs. Mechanical limbs, you just slap them on. Quick, cheap, and easy. Making sure the body doesn't reject a small interface is easy, and it's easy to swap out the limbs if they're damaged or you want a new kind. [Answer] > > While the technology allows for growing limbs and organs to replace those that were lost due to accidents, why do many in the setting still prefer to fix themselves with cybernetic augmentations rather than grow a new leg in a vat? > > > **Money.** OEM limbs and organs are a luxury. Might as well ask "Why do people eat ramen noodles if filet mignon exists?" The masses receive the cheaper mechanical option because it is cheaper, can be found on the second-hand market, and readily upgraded/repaired. If you get a new biological arm and get it ripped off again then you're gonna be pretty upset that you have to shell out for a new one again. If this is some factory worker then it's not feasible to wait for the growth of a new one; bread has to be on the table every night. The mortgage man always cometh! [Answer] Other answers deal well with technological concerns. Along with Azuaron, I would offer sociological concerns. This society might consider biological manipulation unethical, while mechanical manipulation is simply another tool. This debate is currently playing out in military technology development. Some experiments in the 20th century (and likely continuing into the present) experimented on soldiers to chemically improve their capabilities. Imagine these experiments were successful in some way or another. Side effects aside (such as with steroids or methamphetamines) many people were and are horrified by the idea of biologically manipulating people to improve their skills. The same debate plays out regarding creating designer babies. Even if we could remove diseases from their genetics, some people would disagree, whether for religious reasons, or avoiding the slippery slope down the road to eugenics. Mechanical improvements, however, are almost universally accepted in military technological development. Creating new body armor, night vision goggles, full exo-skeletons-- there is little debate about the ethics of these mechanical improvements. So even if biological manipulation was possible, people might be freaked out about it, grossed out by it, concerned that it would lead to eugenics, or just believe that it is plain wrong. Mechanical improvement could have similar concerns, but generally less so than biological. [Answer] **Prosthetics are ancient status items.** In our world, an analogy would be a Stradivarius violin. <https://en.wikipedia.org/wiki/Stradivarius> > > According to their reputation, the quality of their sound has defied > attempts to explain or equal it, though this belief is > disputed. The many blind experiments from 1817 to as > recent as 2014) have never found any difference in sound > between Stradivari's violins and high-quality violins in comparable > style of other makers and periods, nor has acoustic analysis. > > > The fame of Stradivarius instruments is widespread, appearing in > numerous works of fiction. > > > Playing a Stradivarius is special. In your world that is how prosthetics are. They are useful and functional, but are also status items. They are very old, and the method of their make has been lost. Most have many prior users and some have their own names. Such an item is for the very rich, or are passed down as family heirlooms. Any commoner can have a new biolimb grown but if you are the person in this generation who is using the [LongClaw](https://gameofthrones.fandom.com/wiki/Longclaw) leg, that means something. [Answer] Some specific augmentations cannot be feasible using just biotechnology or they are just easier using electronics: * Having telephoto lenses with variable zoom, while being sensible to UV or IR light is a cheap feature using electronics and you don't need lubrication (you can still see even if the wind creates a dust cloud). * You could improve your resistance to frostbite with a better blood irrigation in your limbs, but you'll need also eat a lot to generate that extra heat. Mechanical limbs just don't care about being at 5ºC, they still work and you can spare that energy for other needs. So people tend to prefer to have a "normal" body, but for some jobs you want a real upgrade [Answer] **Biological Security** The motivation is similar to how some people prefer to use more primitive phones and computers for privacy reasons. These simpler devices have fewer ways to secretly gather data about the user. If you are worried about the smartphone recording everything you say, even when you are not making a call, and you don't know enough about smartphones to take it apart and decode what information your smartphone is recording (and to whom it gets sent), then the solution might be to not use a smartphone at all. Likewise you don't know what hidden features that new arm or liver might have and what hormones it is pumping into your immune system. Perhaps the company that makes the arm is part of an umbrella corporation and it releases a chemical that makes you drink more Coco-Cola? The genetic code is of course patented and you cannot see it. Even then you would not understand. A mechanical arm on the other hand does not have room for such nefarious schemes. The arm has exactly 2 interfaces. One with the nerve endings and one where you plug the arm into the wall to charge at night. [Answer] **Biology is its own limitation** There are material limitations, and what you might choose depends which you prioritise. Do you want the advantages of bio tissue, or the advantages of inorganic fabrication? Or some kind of blend? Other answers have suggested temperature range and scale of touch as benefits to inorganic. But really, organic tissue is its own limitation. It damages readily, has limits on strength, pressure, tension/compression, sensory detection, form and shape (hence functionality), options for swapping between accessories as may exist with inorganic, ..... And we don't know what exactly they can do with biotech. Maybe just crude gene fixes, maybe entire new body forms. Depends which features you value. ]
[Question] [ The gods in this setting are extremely powerful but limited beings, who are similar to humans in their mind and decisions. The gods are the highest powers in the world but originate from reproduction in the same way as other organisms. The main feature separating the gods from other creatures is that many gods have labels written on their body in various places, that show names, titles, or qualities of the labelled god. The gods have various levels of labelling, and some gods are not labelled at all. Every faction of gods has both labelled and unlabelled members, and some of the most powerful and lawless gods are also labelled. Several gods have inaccurate labels. What reason could there be for the gods to be labelled? [Answer] ## You Label Me, I Label you... So we're talking fantasy and magic, so rules are a bit loose. Your universe is a magical one, and magic is often intrinsically linked to the power of words. The words wizards say invoke powerful forces of the universe. But while humans and their words invoke these power of these words to manipulate the magic, your gods are a step closer. Your gods interact with the power of language directly, touching the mystic words themselves, and can thus directly manipulate reality. You specified that the labels are not always accurate. So they don't correlate with the meaning of the words, or the judgement of some even higher power. That gives us a few options. * **Contamination**: The essences of these words is clinging to your gods like magical stains. A wizard is at "arms length" when contacting magic, but the gods touch it directly. Interacting with a word frequently leaves an impression that has a physical manifestation. Conversely, touching magic radically different than what one deals with regularly might also leave it's mark as inexperienced hands mishandle the power. While the gods are powerful, this is the essence of their power. They don't know how to remove these stains. They may be useful, connecting the gods to underlying mystic power, so then they wouldn't WANT to remove them even if they could. If they are accidents, then younger gods who have been shown the proper way to use magic won't get them because they know how not to. * **Artifacts**: These labels were once attached to different beings. World mythologies inevitably refer to ancient, pre-existing pantheons of gods who are overthrown by the current gods. These labels represent things that once made sense in another frame of reference. So if god X ('the Sea Lord) killed or overthrew god Y ('the whale of the universe') a thousand years ago, X may now find himself marked with "whale." These artifacts may or may not contain intrinsic power, so when Apollo kills Python the oracle of Delphi, he may take on the power of the oracle. Or they can be things made by previous god just for vanity - divine swag that now sticks to their descendants like a bad tattoo. * **Divine bad judgement**: Like tattoos, labels are forever. Your gods are no wiser than humans, and humans aren't all that wise. If your gods are long-lived, they may have used permanent magical means to title themselves or others. But the role of gods, and the motives they feel about things, are changeable. The god of fire this year may be a god of fiery war next year OR a god of fiery sun and agriculture. And things may have very different meanings in different contexts. MLK are the initials of Martin Luther King, but once long ago the three letters stood for Moloch, fiery god of human child sacrifice. In all of these cases, the labels are most likely attached to gods who are old, and thus have experienced many things for the first time, or the bold, who are exploring outside their comfort zone in unfamiliar places magically and engaging in risky divine combat and reckless behaviors. Even if there's no intrinsic power associated with the labels, having a label is a mark that you are someone to be watched and reckoned with. [Answer] **In the Beginning there was the Words.** The primordial universe contained only the Words. The material universe was formed as the Words Spoke themselves into physical form. Most of the Words are now gone. The few that remain carry great power. Being some of the earliest living creatures, the Gods discovered how to prevent a Word from Speaking itself -- namely attach the Word to a living creature. This keeps the Word from Speaking itself until the creature dies. Thus all known Words are attached to a God in case it is needed later. Typically they prefer to carry words relevant to their nature, as this makes the power easier to use. These Words are accurate labels. But you might also have several redundant Words in case your nature changes; get a Word as an honorific, or simply be carrying it for someone else. These are inaccurate labels. [Answer] **It is the work of the god of labels** Of all the gods powers, one of the first gods got the power of labeling. His power was to materialize labels everywhere. Power crazed and driven by the enthusiasm of the youth, this god started to label everything: animals, trees, other gods, mortals, stones... Some were correct, other were mockeries (that god was a bit of a prankster). But eons have passed, and now this god has become wiser and has decided to use his powers only in moderation. Of all the things that he labeled centuries before, mortals died, while the labels on the landscape were canceled by erosion. Only the labels on the gods, since they are immortal and their bodies can't change, were left intact. [Answer] **The world is an art project.** Labelled gods are some of the original pieces of the project. They were labelled by their creator or creators. There are other things in this world that are not gods but are also labelled - artifacts of the original project setup. Unlabelled gods and other things are not original to the project but evolved within it, are secondary creations, or are later additions from other projects. They might carry labels from those other projects that are not relevant or make no sense in their current enivrons. [Answer] **Achievement gained: Kill 100 humans with a fork** Your gods are just as vain as humans, so they tattoo on themselves when they do something of note. Killed another god, destroyed a village, started/ended a human war etc. They can also use them to keep a tally of of things like the number of humans they killed or helped. [Answer] Like in an army some members exhibit their grades while others keep them hidden, the same happens for your gods. Reason for showing off one's grade are exhibit of authority and status, for example, while reason for hiding one's grade could be the need to act in covert: who wants to be the primary target of a sniper just because is showing off their rank on the shirt. [Answer] The name is the thing, and the true name is the true thing. By labeling themselves, the gods are invoking great power. The variation is caused by variation in motives: * Some powers are just harder to control than others, and so a god needs a label to get good at them. * Some powers come more naturally to some gods than to others. If you want to be as good as another god, you may need the label. * Some gods desire power more than others and use the labels. * Some gods are lazy and use the labels to replace hard work. [Answer] **Gods are invisible** Some of them like to be seen so they wear labels with their names on. Tricksome gods can forge the label of another god so as to pretend to be them. Some gods are shy or just like to do godly things in secret. They don't wear labels. [Answer] It is a personal ID. The God civilization used IDs, but either they are not compulsory, just convenient to have them (the Denmark or UK model), or maybe they are compulsory from certain age up (much of the rest of the world, minus USA), we mortals just do not know the exact reason (gods can change their appearance for us mortals, so we cannot distinguish the young ones). Since they found it extremely easy to apply the labels, the need for wearable pieces of paper or plastic never arose. [Answer] Gods may come into being by sex like other organisms, but that is just part of the truth. They actually emanate from myths - when the myths say they reproduce, they reproduce. It is actually the people's belief in those gods that shape the deities and their stories. It just so happens that one of the seminal prophets and/or storytellers of this world was also an organization maniac. You know, stereotypical virgo, with a nearly sexual compulsion to have things neatly arranged. The kind of people that buys and uses post-it's, makes schedules for their coworkers, creates processes and comes up with ever new forms and subcomitees. That [redacted] zealot probably had the designs for the original pantheon in a binder, with color-coded spheres of influence. Gods with wrong or missing labels were later added to the mythos by reformists, heretics, apostathes and messiahs who weren't so crazy about organizing. This tangentially rhymes with the work of [Nuggan, the Borogravian God of paperclips, correct things in the right place in small desk stationery sets, and unnecessary paperwork](https://wiki.lspace.org/mediawiki/Nuggan). [Answer] **The rich gods can afford labels** Some gods are fashion conscious. They of course like to wear designer labels as much as possible. ]
[Question] [ An intelligent species of aquatic creatures considers human fat to be a delicacy therefore human flesh is a status food only the rich can afford. There is a problem, those aquatic creatures can walk on land but they have a hard time doing so and they become vulnerable when not in water. Because of this, I need a safe method my aquatic creatures can use to farm humans. People can't escape and they are overfed to become as fat as possible, the fattest and biggest people are bred in order to produce the naturally bigger humans. They are not killed right off the bat because pregnancy is really long and it takes a lot of time for a child to grow into adulthood. Instead, they chop pieces of fat off humans while keeping them alive, and sometimes limbs are cut off but this is rare since it's way more expensive and usually only happens to older people who are about to die anyway. I need a way to keep humans unable to escape, but they also need to have a good food source to fatten them and also safe breeding, all of this while considering the fact that the aquatic creatures have a really hard time on land, so hunting people by foot is not an option. [Answer] Perennial beach parties with fast food attached, along the lines of the internet version of summer breaks in Florida: * free mating between most of the attendees, ensuring reproduction * rivers of alcohol to dumb them down * the fast food will fatten more than some specimen, who would then happen to "drown" If the place where you place the farm is blessed by good weather all year long, you are not limited to the seasonal 3 months of summer. [Answer] **Humans will farm them for you.** Humans are great at keeping other humans captive. Also great at finding good food for humans. Humans have a long history of entering into commercial enterprises that involve selling the bodies of their fellow humans against the will of those sold. Your aquatic folk will contract with surface dwellers to provide them delectable humans to eat in return for desirable ocean riches. Your surface dwellers will either capture people to provide, or raise them for the purpose (more reliable but more expensive). The great part of the story is when it is revealed that delicious salty and smoky fat chopped off of people who are still alive is actually bacon from pigs. The ocean people don't know about pigs and get off on the meanness of eating people alive. And it turns out they love pig fat and are willing to pay big bucks for the eating live humans fantasy. The pig farmers occasionally give them a recognizably human hand or other part, to keep the dream (and revenue) going. Then at the end the ocean people figure out they have been duped for years paying a 100x markup for pig meat. They charge out to attack the pig farmers but wind up in the pig pens where the pigs knock them down and eat them alive. [Answer] For the close voters: the question boils down to "what is the best way for aquatic things to use to prevent humans from escaping their future dinner appointment". Put them on an island. Whenever they want to escape they have to do so through your medium. Better yet: if you can feed them yourself, you put them on a boat that only the aquatics can steer. That way they cannot build their escape vessle (not without you noticing) and you control their wealth, luxury and food intake. A boat can be more like a raft with a few holes in it where the aquatics can poke their heads through. In warmer climates you can have partially flioded area's where the humies and aquatics can relax together (before one is taken "out to land" where he can live the rest of his days and never be seen again, really you should thank us humies that we take such good care of you...) The one's that you start chopping up alive are all located on a seperate boat, so the growing humies arent interrupted by the screaming and escape plans. This way the humies can safely learn fattening habits that they wont shake when they get taken to the boat with the butche- I mean out to land. [Answer] **Raise them in big air-filled tanks, deep underwater.** The humans are kept in what are basically large room-sized diving bells, each with enough dry floor space for maybe a few hundred humans (or whatever number you like) kept in locked pens inside the enclosure. Air can be pumped in from the surface to replenish oxygen and to keep the air pressure matched to the local water pressure. Access is through a hatchway in the floor, open to the water. If these structures are deep enough, escape would be out of the question, as any human who manages to get out will drown before they can reach the surface. One major advantage of this approach is that the aquatic creatures have total control over the environment at all times. If kept on dry land, the humans would have access to an extended environment where they can easily breath, and run, jump, climb, throw things, etc. while their captors are relatively helpless without special equipment. There would be constant attempts at rebellion and/or escape. Deep underwater, the captors always have the upper hand. At the first sign of rebellion they could simply open a valve and flood the enclosure, leaving only a small air gap near the ceiling. The humans would suddenly be unable to do anything but fight for air. [Answer] Just battery farm them and force feed them like your after human Foie gras. One you have a way to catch them (L Dutch has a great idea) take them to safe location where they cant be found by other humans and farm them. By the second or third generation the humans will be used to their immobile obese life, just waiting for food. Scraps from the seas could be brought up and thrown in troughs for the humans to feed on. Manual breeding would have to take place as humans would be too obese to move. [Answer] ## Use a Resource Bare Island Humans have a bad habit of adapting to dangerous situations which makes it difficult get a stable supply of them. The best recourse then is to put them on an island so that they have nowhere to run too. Ideally you should clear the island of all trees and pointy rocks first to make sure they can not make any boats to run away with or weapons to fight back. Once you take away the resources human can use to make all their nasty inventions with, they are basically just caged monkeys. At this point of course, they will not be able to feed themselves very well; so, you'll need bring them regular feedings, but making them rely on you to feed them will also force them to the shores making snatching them up much easier. As for what you feed the humans, most seafood is pretty lean compared to terrestrial food sources; so, you can't just feed them a bunch of seaweed and fish and expect them to get fat. Instead you will probably need to prepare your human food with added fats and/or sugars. Added sugar is hard to process underwater; so, I would suggest "enriching" thier food with the blubber from whales, seals, or dolphins to make sure they put on enough calories to get the humans all fat and tasty themselves. Because mammals store fat in separate layers from thier muscles this makes properly butchered mammal meat a better source of empty calories than fish. **As for the Bounty looking for a credible source:** Your need a system that does two things very well. 1: It must detain people, and 2: it must make it easy for a water predator to catch land based prey. So, this question draws inspiration from two sources that are each individually REALLY good at that. When it comes to detaining human beings, the best experts in the world at that are the people who design and run maximum security prisons. They regulate the hell out of what the prisoners are allowed to own because they often use relatively mundane items to fashion tools and weapons. By stripping the island of resources, you are replicating this precaution. The second thing they do is create an exclusion zone around the prison to make sure there is no where to run to. While many prisons use deserts or other kinds of wilderness, the most effective exclusion zone is always water such as you see with Alcatraz prison; so, using an island is not just about what is convenient for your aquatic life forms, but what is hardest for your humans to get away from. As for the water predator, I take a certain amount of inspiration from Nile crocodiles. Most aquatic animals don't have much luck hunting land based animals, but for crocodiles it is easy. In places where they live, land animals are 100% reliant on the water where the crocodiles live if they want to survive. By feeding the humans, you create that same absolute need for humans to go to the water where the predators are for survival. If you can bring them to the water, then like the crocodile, you don't need to leave the safety of your home turf advantage to pick off otherwise dangerous prey. [Answer] The answer? Slave trade. People are dickheads and will happily trade other people into conditions that will lead to their death. If the water creatures pay some land-based mercenaries with some sort of under-sea riches like pearls then the human mercenaries will take poorer or less capable people and sell them to the sea people. If these slaves are not up to the standards of the oceanic things then they could be fattened by them in big air-filled tanks, being fed on enormous crops of algae. [Answer] The obvious way is for the creatures to exchange treasure for human blubber. If they are intelligent, they must have recognized that humans are too, and communication was possible. Either for self-preservation or greed, some human would surely have proposed an exchange between their meager endowment of body fat and a much larger and/or steady supply. Human fat can be harvested from several sources, not necessarily involving murder or bodily harm. The cremation business would be a viable alternative: offer very cheap rates, remove the prime cuts, reduce the rest (and any manufacturing byproducts) to ashes. Also, the creatures almost certainly developed a yen for human fat from drowned humans. It was a low hanging fruit; it stands to reason that there might be *lots* of other, perhaps even more sought-after delicacies just waiting to be discovered, that never were because they were never involved in a shipwreck, or never recovered in time: examples in literature abound (maple syrup in *Live free or Die* by John Ringo, ginger in the *Invasion* cycle by Harry Turtledove, tobacco in *Iceworld* by Hal Clement). In time, the creatures could also supply cheap workforce for all sort of underwater enterprises. It would be probably weird to have a multinational conglomerate owning liposuction clinics, crematoriums, underwater salvages, plastic recycling, deep sea mining and prospection services, but nowadays diversification is all. [Answer] Humans or other terrestrial animals could be kept in air-filled tanks deep below the ocean's surface, for the purpose of underwater farming. This is analogous to the process whereby aquatic creatures, bred for eventual consumption, such as fish or shellfish are kept in water-filled tanks in the air. Several factors would need to be accounted for, such as oxygen levels, barometric pressure, toxicity, etc. These conditions could be brought within a range habitable to humans with a series of vents, pumps, and filters with only a modicum of effort. [Answer] **Immobilise ships**. This shouldn't be too difficult for any semi-intelligent aquatic species with access to tools or strong physical forms. Encourage the crew to eat up their emergency rations and throw the occasional survivor or recent corpse over the side by promising to release the last survivor to the port of their choice. Obviously don't as this would breach the secrecy of the operation. Any escapees should be relatively easy to overcome (or you simply immobilise their ships as well). Provide additional human-suitable food once they run out of rations. So long as it is a mixed-sex crew they can then reproduce and provide more humans. If the gender ratio isn't right a few beach-based kidnappings could even things up. Doing so in an area of high navigational uncertainty (or in the Bermuda Triangle) would cover up what is happening for a while. This gets hard once the humans invent GPS, reliable ships, satellites and planes unless the aquatic race have some other tricks for remaining unseen. Eventually they will catch on. At which point, assuming the humans aren't significantly technologically superior, the aquatic race can negotiate a 'toll' with a mercantile nation for protection of their shipping. [Answer] # Play God: If people think they are serving a god, they will do anything. * people have offered human sacrifices to gods for thousands of years. All you need to do is have the Sea People play god and ask for offerings of the fatted human. You wouldn't need to cut off parts, just ask for the whole sacrifice - especially a voluntary sacrifice raised from childhood to believe they're special and chosen. * Or (as a variant on the other questions) the culture can capture prisoners, force-feed them, and offer them up Aztec-style. This works even better if there is a reciprocal relationship, so the gods have something to offer, like drugs or gold (or offerings in return? Religion can be funny). * Cultural practices around death can be turned into burial at sea, where all the dead are available to feed the hunger of the undersea gods. People might even be offended if the gods refuse to eat their dead, denying the dead the chance to "become one" with the gods and attain spiritual immortality. * Isolations would not be needed, but could help reinforce the consistent message of the gods. After all, those zealots who came to convert them and spoke blasphemy of the gods all died when their ship inexplicably sank, right? Naturally it's the will of the gods. ]
[Question] [ My question is based on the following excerpt from an [article](http://www.human-memory.net/processes_storage.html) I read recently: > > *Since the early neurological work of Karl Lashley and Wilder Penfield in the 1950s and 1960s, it has become clear that long-term memories are not stored in just one part of the brain, but are widely distributed throughout the cortex. After consolidation, long-term memories are stored throughout the brain as groups of neurons that are primed to fire together in the same pattern that created the original experience, and each component of a memory is stored in the brain area that initiated it (e.g. groups of neurons in the visual cortex store a sight, neurons in the amygdala store the associated emotion, etc). Indeed, it seems that they may even be encoded redundantly, several times, in various parts of the cortex, so that, if one engram (or memory trace) is wiped out, there are duplicates, or alternative pathways, elsewhere, through which the memory may still be retrieved.* > > > Is it, therefore, theoretically possible to create a machine that perfectly maps out the way in which neurons fire in Patient A regarding a certain memory, and then to stimulate an identical firing of neurons in Patient B, so as to allow them to live that memory or even believe it to be theirs? By extension, could this machine map out the neuron firing order that occurs while someone studies mathematics or physics, and then to replicate such firing in another person so as to impart that knowledge upon them? Or is there some additional element that arises when living through the experience yourself that cannot be reproduced in such a binary fashion as "firing of neutrons". If so, what does that say about the passage quoted above? [Answer] > > a machine that perfectly maps out the way in which neurons fire in Patient A regarding a certain memory, and then to stimulate an identical firing of neurons in Patient B, so as to allow them to live that memory or even believe it to be theirs? > > > This can only work if the wiring of the neurons in our brain is standardized and homogeneous like the circuitry in a high end smartphone. Sadly, that's not the case. It is known that from the moment we are born any experience we have remodel the neurons and their connection: those more used are kept, those unused are discarded. This means that no two persons have the same neurons and connections. Thus, at most, firing pattern(A) into B would result in noise, like opening an encrypted file without unencrypting it. [Answer] To "replicate such firing" is, as noted, impossible in 2 different brains. They are just too different. However, consider that right now, you are reading these words and my thoughts are becoming your thoughts. We have both spent years learning English in order that these formations of black and white pixels fire the correct neurons. This learning process standardized our brains. Not on a neuron basis, but on a concept basis. If the machine can see these concepts, and create and connect new neurons to hold these concepts, to do "direct neural learning" the machine would need to know how both brains encode concepts and translate from one to the other. So if you wanted to learn physics from Einstein, you'd also need anything tangentially related in his brain: basic math, calculus, German, patent office forms. The machine could match his basic math to your basic math, concept by concept, neuron by neuron, and so on, and create only additional the neurons it needs to encode new concepts. (Or just overwrite vast sections of your brain! You'd know physics, but might be confused as to why you are not in Princeton in 1955.) Computers do this all the time with emulators, cross compilers, Just In Time compilers, boot loaders, and whatever WINE is (WINE Is Not an Emulator), but computer memory is easily mapped and insignificant by comparison. [Answer] No, each person brain is different and the map from one will not produce the same results in another. Due to plasticity and how each brain is individually trained to your sensory organs and experiences each memory in each brain is unique. Each brain a has a unique map of connections called a [Connectome](https://www.sciencedirect.com/science/article/pii/S1053811913010057?via%3Dihub). A perfect copy of someone else's memory would require identical brains otherwise the linkages will not match up with the rest of the brain. Your map for concepts is not identical to mine, so the connections will not be to the same concepts. Your spliced inot connections will produce nonsense. Research into [artificial senses](https://www.aao.org/eyenet/article/bionic-vision) show the same problem, their solution is an extended process by which the brain and the interface learn each others connections, basically the same way you learn to see with your eyes as a baby. [additional source](https://nba.uth.tmc.edu/neuroscience/s4/chapter07.html) [Answer] I recall reading an article where scientists did this with mice: <https://www.smithsonianmag.com/innovation/meet-two-scientists-who-implanted-false-memory-mouse-180953045/> I don't see why, with sufficiently advanced technology, we couldn't do something similar in humans. I suppose it would depend on how vivid and complex you want the memory to be. ]
[Question] [ (This is part of a game I'm making, with a bit of backstory [here](https://worldbuilding.stackexchange.com/questions/113133/how-much-metal-could-a-humanoid-safely-have-in-its-skin-and-bones-and-be-functi).) **Details:** Size/Shape: Roughly oblong and quite large. Length of 15 miles, and a greatest width of 8 miles. Placement: 500 miles south of Perth, Australia. Environmental effect: Due to handwavium reasons, the appearance wouldn't significantly effect the surrounding environment. It can be seen, landed on, all that. However, it won't effect sea levels or anything. It will be sensed by all modern technology and biological functions (of humans AND animals). Land: It will be covered in a temperate rainforest, in case that helps anything. Timeline: The appearance of the island takes 6 hours. This finished taking place right "now." Method of appearance: A thick fog rolls out of the ocean, and over the course of 6 hours, the topmost edges of it seem to solidify into a real island. From below it looks like fog that you can't see through. From the top, like any other island. So, how and when would an island this size, in that position be discovered? [Answer] ## Days, if not hours 200 nautical miles is the exclusive maritime territory, which translates to about 370 km. Any Navy ship patrolling that region will spot it at the edge of its range and investigate. EDIT: I would expect a routine patrol would pick up a large unidentified object at extreme range and call it in. Wouldn't do to let an invading armada pass by, just because they had to go out of their normal patrol route. HQ will probably inform any satellites passing by to take a closer look. If satellites aren't available within a few hours, they'd send a couple of jets to fly by at high speed. "Island? What do you mean, just an island? There's no island there!" [Answer] At first I was agreeing with nzaman (who just got my upvote) but then I hesitated because of the explanation and decided to write my own answer. * The area will be overflown by military recon sats several times a day. Those pictures may or may not be examined humans quickly. I wonder if there are computer algorithms that would detect such an *unexpected* event. * The island is large enough to show up on civilian and military weather sats and those pictures will be examined in near realtime. The question would be just how closely the images are examined -- the discoloration might be mistaken for a cloud at first. * The appearance may cause seismic events, depending on the mechanism. Does your handwaving cover that? * Maritime patrol aircraft don't provide 24/7 coverage that far out, I believe. The [Fleet Air Arm](https://en.wikipedia.org/wiki/Fleet_Air_Arm_(RAN)) has no more fixed-wing craft. The RAAF has a total of 26 Poseidons and Orions, based in RAAF Edinburgh but I guess they are oriented northwards ... [Answer] ## It could take a very long time [Sandy Island](https://en.wikipedia.org/wiki/Sandy_Island,_New_Caledonia) is a [phantom island](https://en.wikipedia.org/wiki/Phantom_island) that was added to maps in 1876. There are also mentions of a "Sandy I." as early as 1774, but it's unclear if it was the same island. It was about 1,000 km north-east of Brisbane. It was removed in 1974 by the French Hydrographic Service and in 1985 by the Australian Hydrographic Service after flybys, but other countries kept it in their maps. It ended up being visible on Google Maps until 2012, when a surveyor ship actually went there and found nothing. Now, we do have lots of satellite imagery being taken every day, mostly weather and environmental stuff, but also mapping. However, unless somebody is actually continuously running image comparisons on all of them, they are useless for finding new islands. Especially one that's 300 km2. I would guess that there are some very smart image comparison algorithms out there running on very localized, high-value targets around the world, but terrorism and fuel enrichment plants are rare in the south-eastern parts of the Indian Ocean. This is a screenshot from [MarineTraffic](https://www.marinetraffic.com) right now where I added an orange dot 500 miles south of Perth: [![enter image description here](https://i.stack.imgur.com/VaUR7.png)](https://i.stack.imgur.com/VaUR7.png) The shipping traffic in the area seems negligible. Since you seem to have explicitly disallowed ways other than visual to spot the island (such as seismic events), unless you put the island smack in the middle of a busy lane and have ships bump into it, you could stay undetected for a long time. [Answer] How: most likely by commercial shipping traffic departing from South Africa or Fremantle to New Zealand or South America. When: probably within three weeks to a couple of months. This section of ocean is very lightly trafficked and patrolled. <https://goo.gl/images/XycHt7> [Answer] **Three business days**. That would be the most likely time, 50% chance it's sooner and 50% later. Takes two days to get the first images, one business day to process the discovery. There are ~[150 observation satellites](https://en.wikipedia.org/wiki/Earth_observation_satellite) orbiting Earth, with the typical orbit being 800km. Each satellite scans about 200\*40,000=8,000 km^2 every 100 minutes. Earth's surface being scanned is ~360 million km^2 - the other 150 million near the poles is largely ignored. This amounts to 120,000 km^2 or 1/3,000 of the surface scanned per minute, or 1/50 per hour. There is a lot of overlap between scan areas, hence the 50% qualifier in the beginning of the answer - can be sooner, can be later. Still, in four days, it's all but impossible for the island to stay undiscovered. While earlier discovery by shipping or aircraft is possible, it's highly likely to go unreported due to simple assumption one is mistaken and the "someone else's business" effect. ]
[Question] [ Is it possible to create a scenario where nuclear power is a practical option for nomads living like in Mongolia? There's two possible applications of nuclear power. One is to just use it as a heat source. The nomads have limited access to wood, so it's too valuable to burn, and their philosophical principles mean that they can't use animal dung, as the only animal products their philosophy allows are dairy and wool, and not dung. This is a departure from real life, in that vegetarianism is [uncommon but not non-existent](http://www.mongolia-trips.com/travelling-mongolia-vegetarian/) in Mongolia. In case you're wondering, the use of dung is [considered non-vegan](https://vegetarianism.stackexchange.com/questions/995/is-animal-dung-considered-non-vegan). Terry Pratchett in "Lords and Ladies" referred to people banging two subcritical rocks together to "keep warm". The other is to generate electricity. Even though they aren't extremely rich, they have satellite TVs. There's no barriers on what technology they have, but they are fairly isolated, such that you can't have an [electrical grid](https://worldbuilding.stackexchange.com/questions/76274/how-can-i-build-a-nuclear-reactor-in-my-backyard). In addition, as they're nomadic, the nuclear reactor and fuel can't be too heavy - about the weight and size of a large fridge. If necessary, the elements and isotopes involved can be different from those found in real life, such as having different half-lives, but the basic concepts involved with nuclear reactions should remain the same. The planet should be millions or billions of years old, not thousands of years old. Ideally, the materials should be simply lying on the surface of the earth, without the need for large-scale mining and refinement operations, but considering that some nomads used to use diesel, it's not a hard requirement. The use of nuclear materials doesn't have to be totally safe - the burning of [material inside homes](https://en.wikipedia.org/wiki/Indoor_air_pollution_in_developing_nations) goes on in real life, and has major health impacts. Severe cases of acute radiation poisoning aren't acceptable, but long-term cancer effects are. For the purposes of this question, solar panels, [which are used in real life](http://www.aljazeera.com/indepth/features/2013/12/mongolia-nomads-warm-solar-power-201312813468350849.html), don't count as using nuclear power. [Answer] They could use [radioisotope thermal generators](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) like those that were used as energy generators for satellites in the past. The one that was used on the cassini spacecraft (picture in the link above) looks as if it might be transportable with a horse or at least with a cart drawn by one or two horses. Three of those power sources combined (I first missed the part that the orbiter had 3 of them) provided around 880 watt at the beginning of its operational life (1997) and now still provides around 660 watt (2017). This isn't much but should be able to cover the direst needs. In addition to the electrical output they generate a lot of heat (4400W each or 13200W for the trio) which could be used by the nomads. Thanks to WhatRoughBeast for pointing this out. When camped foldable solar panels could be used to increase the power available. [Answer] ## No, nuclear power is just too complex (to get to on their own). We, this modern world, got our nuclear toys due to the work of a lot of smart people. I think the Brits were the [first with workable](https://en.wikipedia.org/wiki/British_contribution_to_the_Manhattan_Project) plans to create it. The [Tizard Mission](https://en.wikipedia.org/wiki/Tizard_Mission) gave those to the USA. But it took the USA's industrial base and manpower to build the first version. This we call the [Manhattan Project](https://en.wikipedia.org/wiki/Manhattan_Project). To give an impression of the size of the project, let me quote this: > > The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US $2 billion (about 27 billion in 2016 dollars). Over 90% of the cost was for building factories and to produce fissile material, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada. > > > Once you know that a technology is possible it tends to be developed faster by [other](https://en.wikipedia.org/wiki/Nuclear_power_in_India) [countries](https://en.wikipedia.org/wiki/Nuclear_power_in_France). Or just steal the [tech](https://en.wikipedia.org/wiki/Soviet_atomic_bomb_project). The problems for your nomads to get to a Manhattan project will be at least two fold: **First** is that they don't have the industrial base to make anything that big. You need to stay in place. Heavy industry is anything but mobile. **Second** is the manpower. Nomad population density is very low compared to agriculture or cities. Tech innovation is way more likely to happen with more people that don't need to watch the herd. --- **Nuclear Weapons and Nuclear Power** There were some questions about the link between nuclear power and nuclear weapons. A large part of the [production line](http://www.neis.org/literature/Brochures/weapcon.htm) is the same. ~95% I estimate. If you can do one part, you can do the other. `Ask the Iranians about that one` The second problem with nuclear weapons is with the bom delivery. `Ask north Korea about that` If you go for defence (and deterrence) you don't need rockets, you might just have them as [mines](https://en.wikipedia.org/wiki/Blue_Peacock). --- ## Comparison of Tech, The first [steam engines](https://en.wikipedia.org/wiki/Steam_engine), [combustion engines](https://en.wikipedia.org/wiki/History_of_the_internal_combustion_engine), [motorcycles](https://en.wikipedia.org/wiki/History_of_the_motorcycle) and [cars](https://en.wikipedia.org/wiki/Car) were built by a few people. One man alone or a small team < 5 people could make them. [Aircraft](https://en.wikipedia.org/wiki/History_of_aviation) are a bit harder, you will need teams for that, ~10 people. *The above might be possible to build up in a nomad society, might. The next ones, you will see for yourself.* [Rockets](https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html) are the next (big) step up. Our modern rockets owe a lot from the [V-2](https://en.wikipedia.org/wiki/V-2_rocket), which were developed by a state, at the cost of ~20.000 lives and many more people working on it. Only now are we coming near nuclear tech. I reckon it is in the same order of difficulty (can't find good links) of computers and space ships like Soyuz and the Space Shuttle. It takes **large states** with a large industrial base and the will to invest to get there. --- ## Unless **1)** they are given the tech from outsiders. Our modern nuclear tech is not (mostly, see 1B) mobile and quite hard to learn to maintain. **1B)** See [Umbranus](https://worldbuilding.stackexchange.com/a/79126/34012) answer. **2)** Some handwavium and the Mongol empire-like. Where they do the industrial revolution and as a state desire to develop nuclear tech. But I just don't see it happening. (Heavy) Industry is just not compatible to nomad live style. [Answer] Yes, but you're going to have to relax your requirements and expectations a lot to make it work. China is currently developing [nuclear reactors](http://www.popularmechanics.com/military/research/a23352/china-is-designing-portable-nuclear-reactors/) the size of a shipping container. These would be more than satisfactory for the needs of a nomadic people. But this is just the reactor, none of the infrastructure that goes into supporting it. You've already moved away from the traditional image of the nomad by declaring they have access to satellite television, so it's just one more step for your culture to use vehicles in place of the horses and camels normally associated with nomadic cultures. There is precedent in reindeer herders -- who are nomadic to follow forage for the reindeer -- [using vehicles](https://www.secretcompass.com/expedition/nenets-reindeer-migration-arctic-expedition/). Still, a convoy of trucks rolling across the plain seems far from what you wanted. But, you may have a solution already. You declared these are a nomadic people akin to the Mongols, and that might be the saving grace for this scenario. [Mongolian nomads](https://en.wikipedia.org/wiki/Nomad#Common_characteristics) move only twice a year, once in summer and once in winter. The winter home is usually in a valley. The nomadic people could have a cooperative relationship with another people who have built a permanent city in the valley and provide the nomads with the technology and infrastructure necessary for the high-tech society you want your nomads to have. You need some connection to a spacefaring society in order to support satellite television, after all. So, yes, there is a way to make it work, but it's not realistic. [Answer] I see multiple problems with this that would make it extremely unlikely if not outright unviable. Nomads in Mongolia type country that don't eat meat? What are they eating? Grass? Nomads don't grow crops, they don't have vegetable gardens, they herd. Herders eat meat and they utilise every part of their herd animals that is useful. If you only utilise part of the animal like milk then you have a huge problem, you have animal corpses to get rid of, and you need exponentially more animals to provide the protein you need to sustain yourselves and trade. Everything you used to produce using animal bits (just about everything) you now need to trade for. Your only assets are animals, so you need much more of them, it's not a simple food equation. Your whole economy is unstable and extremely vulnerable. You need bigger herds so more people to herd/protect. And you have everyone subsisting on milk and substituting grass for what animal products are used for (almost everything). If you can't use animal products like dung, you can't use sinews, skins... so you're making houses out of twisted grass etc,. sewing clothes and wounds together with grass.... what will you use for needles? Grass? You don't develop hunting skills or weapons, so you're sitting ducks for any belligerents. Basic Mongolian bows were made from horn, bone and sinew (not grass). Their armies were trained by hunting. You just took out THE major part of their economy. Everything from glue to eating utensils you now have to make from grass somehow. It's the major thing that made their way of life sustainable. With the Nuclear bit, they're not going to find viable nuclear materials lying around easily accessible, we don't find them today like that. We also need to produce heavy water which in itself is a mission and is done on an industrial scale. (I have a very limited knowledge of nuclear physics and materials, but this is my understanding). In any case everything takes a lot of processing before it can be used and Nomads don't have labs and stuff like that. They don't mine metals, they don't have factories, they don't do a lot of necessary things. So the only way I think this could happen is if some third party was giving them these nuclear powered units. I can't see them ever producing them themselves. So without some serious hand waving at multiple points in your story you can't do this. [Answer] As long as you are just using nuclear reactors and not making them yourself you should be good to go. Not only that you could use RTGs, you could use full fledged nuclear reactors. [NASA's SAFE](https://web.archive.org/web/20041022135357/http://www.spacetransportation.com/ast/presentations/7b_vandy.pdf) reactor should provide you with 30 - 300 KWt (that fit a fridge size). [Students at MIT](https://stuff.mit.edu/afs/athena/course/22/22.33/FINAL%20REPORT/22.033%20MSR%20Final%20Report.pdf) designed this 1MWt / 125 KWe reactor for their hypothetical mission to mars and it weights 2 tonnes. Both reactors are high-temperature (meaning they can be cooled by radiation only), use heat-pipes which makes them less susceptible to damages due to movement and can fit into a (very) large fridge. As bonus points you can use residual heat to do whatever you want including heating, melting softer metals, desalinating water, maybe even producing hydrogen from water... Shielding is a problem. I am not sure how much gamma radiation do these reactor emit, but you might not need a lot of shielding. If you are traveling the steppes and deserts you don't really care if you are irradiating anything except your people. Just put reactor at the end of convoy and shield it in front. You will irradiate ground, air, everything to the sides of you and everything behind you, which is empty useless space anyway. [Answer] A nuclear reaction can occur WITHOUT technology if the world was the right age so the concentration of U235 in uranium ore is high enough that normal light water (as opposed to heavy water) provides enough neutron moderation to allow a chain reaction. This is exactly what happened in Gabon 1.7 billion years ago. See <https://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor>. The estimates from the linked article show 100 kW of power generation - not too shabby! **But... it would not be portable.** The nomads would have to be on top of a substantial amount of uranium bearing ore. Nuclear powered oases perhaps? [Answer] The aforementioned thermoelectric nuclear reactors like the Topaz use heat emitted to make electricity These weigh 2 tons+ so are outside of your fridge weight limit. I propose that chunks of isotope which are kicking out lots of decay heat be used to drive steam boilers, which generate electricity. That does not involve swanky space tech. A steam boiler can run on anything hot. The scheme requires: 1. **Hot chunk of isotope.** [![enter image description here](https://i.stack.imgur.com/YQiiv.jpg)](https://i.stack.imgur.com/YQiiv.jpg) from <http://newatlas.com/nasa-cancels-advanced-sterling-radioisotope-generator/29880/> Shown is the hot guts of one of those thermoelectric generators. Your nomads would find these glowing chunks as asteroids that fall to the ground. They would be identified by surrounding dead patch / snowmelt. Pick them up with tongs and put them into the lead-clad iron box. Quickly. This might be a job for the oldest and sickest among you. Then get the box into your boiler before the lead starts to melt. Don't let your boiler run dry. 2. **Mini steam engine.** From <http://www.dangerouslaboratories.org/genset.html> [![enter image description here](https://i.stack.imgur.com/O8Cxu.gif)](https://i.stack.imgur.com/O8Cxu.gif) You could definitely tote this cute little rig behind a goat. To do the Mars project there must be isotopes which kick out enough heat for long enough to make it practical. You would not want to get to Mars and find out your hot chunk of isotope had cooled off 6 months ago while you were en route. A question I was not able to answer to my satisfaction is whether there exists any isotope which kicks out heat like this for many years. I think these hot wads of plutonium isotopes are synthesized & certainly concentrated, not mined up as glowing nuggets. If the nomads find a hot meteorite, what was it doing 100 years ago? 1000 years ago? Are these being produced in space by some natural process? Nearby supernova? That is the one dissatisfying aspect to this - the provenance of the high decay heat radioactive asteroids. Re leukemia / cancer risk: do not ingest glowing isotope. Do not inhale glowing isotope. Use tongs and wear gloves and thick apron when handling glowing isotope. Put glowing isotope promptly into box. When radiation causes cancer it is usually from prolonged direct contact to particle emitters (e.g. watch painters licking brushes with radium paint, Marie Curie carrying radium in her pockets), inhalation of airborne radioactive material (e.g. Chernobyl accident) or therapeutic radiation used to treat cancer. Chunks lying around are bad if you are a weed growing next to it, but these chunks would not produce a countrywide blight. [Answer] So some answers seem to think you're talking about actual Mongols rather than just using them as an example of nomads. But maybe like they were part of the modern world but then decided to live a different life. There are loads of small(ish) nuclear reactors like the chinese one that fits in a cargo container or the ones in nuclear submarine (they could even be marine nomads). If they can pick up diesel I guess you allow them picking up the nuclear fuel too. I don't see a problem with it. [Answer] # Sure. It's called a [Radioisotope Thermoelectric Generator (RTG)](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) They can be small, last a *really freaking long time,* and require no maintenance as it *has no moving parts.* One the size of a portable gas generator (we're still talking 100 pounds here, but load it into a truck? Absolutely) can output enough power for a small home. One or two could easily supply a tribe of nomads with enough power for a stove and some lights. Downside, they're not terribly efficient (about 7%; yuck) and their power output drops over time (about 0.8% per year) as the radioactive material decays. I can't find the story now, but there was a report of two fellows who found this device that seemed to generate free energy. Perpetual motion sort of deal. They had no idea what it was and used it to power their house for around a decade. Later turned out to have been a Russian RTG that fell off the back of a truck. Besides powering Russian lighthouses, they're frequently used in space probes due to the long lifespan and minimal maintenance. Voyagers 1 and 2, Galileo, Ulysses, and New Horizons all have one. Voyager 1's operational capacity was 470W at launch and by 2001 it would have dropped to 315W. [Answer] Both RTGs, and ny kind of reactor is not realistic by far. **RTGs**, while light and not having many moving parts, are not radiologically safe to be around. Unless you understand "being around" as deploying it and having a no-go zone 200 meters wide around it, until it stops working by itself. While it is somewhat-useable on an unmanned space probe, or an automatic weather station in a polar area, its not feasible for any real use with people around. **Reactors** are a step above that. They need heavy shielding around them (the pressure vessel alone will NOT cut it enough), they need support infrastructure (turbines, steam dehumidifiers, 2 or 3 (VERY) high pressure coolant loops (of which first one is deadly to be around just like that, due to radiological hazard, and they need large amounts of water (all nuclear plants, sans literally ONE, in the worlds, have either a river, lake, or similar water source nearby). Furthermore, fuel. You cant just put a natural uranium ore or unenriched natural uranium into an RTG or reactor. Reactor grade fuel means 3-5% enrichment (you need an enrichment plant for that). This is the easy fuel. RTG's do not work on uranium - they use plutonium (highly purified, too! RTG plutonium fuel pellets relase realy obscene amounts of heat due to its high isotope purity and high activity), which is not found in nature unles you breed it (for which process, in turn, you need a specialised breeder reactor, and enrichment plant). All of which are high level of complexity, highly dangerous (radiation, chemicals used) heavy industries. [Answer] I'm not seeing a way to make this work well, as stated, for the following reasons: 1) I would think that large amounts of radioactive material lying close to the surface would be a massive, cancer causing blight in the area. Something much worse than the products of incomplete combustion. You are going to run the risk not only to the health of the adult population, but you might also get some nasty complications for children and such, reducing the number of surviving children, or children who don't survive long enough to reproduce due to leukemia and so on. The medical repercussions would be awful. Regardless of the material you could use, if it's close enough to the surface, you are going to be exposed to damaging radiation. 2) The specifics of HOW you use the radioactive material. An RTG is an option, but the fuel can be very harmful. It's not impossible to use, but very risky. Full on fission reactors would be almost impossible, even with small reactors as found in submarines and Chinese cargo containers. You have to move them, and they are very heavy. If you are doing traditional nomads with dray animals, you are stuck. You also need a means to process the radioactive material from ore into something useful. Here is how you MIGHT make it work. Your world is a post apocalyptic wasteland. Load your reactor up in a mad max like heavy rig that is electrically powered. other vehicles are stolen from the Tesla factory and can recharge from the truck. Your people are raging, militant vegans. They move around and raid farms, stealing the produce and freeing all the animals. Every so often they return to the old nuke reactor for more fuel. Constant exposure to the radiation is going to weaken them over a number of generations, so you want to set it within a couple hundred years from the catastrophe. I'm not totally sure of the science, but I think I could buy it from a layman's perspective. [Answer] yeah, but they're not going to do it well. It also depends on what you mean when you say nomads. Nomads just move around a lot, they live on the run. Doesn't mean they don't mine sometimes. You do also get to decide geography which is really useful and you don't require the nomads to have clean nuclear power. Your nomads could just get really really really lucky and find a mound of thorium and a place were you can get the right isotope of uranium. They could just drag furnaces around with them to burn this stuff. Hell they could even just put this shit in batteries. Just stop and charge up a capacitor and then have the capacitor dump its charge into a battery very slowly. This wouldn't be efficient enough to be practical by modern standards, but fuck it these nomads have nearly free nuclear energy. They should be able to waste as much energy as they want and still be fine, cause Thorium. I have no idea how they're planning on dealing with the waste though. Thorium is pretty powerful stuff too. Thorium also meets all of your requirements. The hard part about using Thorium as nuclear fuel is getting the right isotope of uranium to start the nuclear reaction. If they can maintain this reaction then they shouldn't need too much of it. This isn't the most unlikely scenario, but I'd call bullshit on it. But if they had lightsabers too..... [Answer] Why not? If we agree to > > If necessary, the elements and isotopes involved can be different from those found in real life, such as having different half-lives, but the basic concepts involved with nuclear reactions should remain the same. > > > Looks like this plane will be known in future as Kirkasan from novel Starfog by Poul Anderson or one like it. Let's say people arleady arrived and semi-crash-landed. Some time passed so they adapted to radiation level (ones who couldn't just died). They also regressed slightly (but not progressed back to space age yet or nomads decided they don't like core population and decided to go away). There are A LOT of heavy elements here, even including transuranium ones. So this nomad tribe just use radio-termal generators with natural (for them) isotopes. If nomad tribe NEEDS SatTV (this includes somebody must be launching TV Sats and produce electronics for said SatTVs)...well, let's say they are splinters from core population and core population is arleady back in space age. There is one small issue here - according to novel - they are no longer human per DNA analysis. They can't have children with regular humans. [Answer] I don't know how realistic it was, but the steampunk book [Everfair](http://www.goodreads.com/book/show/26114130-everfair) featured airships powered by small nuclear reactors. I think it was partially handwavium combined with "indigenous priest knowledge", but it leveraged the naturally occuring uranium deposits in the Congo. ]
[Question] [ How would the rules and regulations look like? Maybe, would there be campaigns to encourage broom travel, as it's pollution free. --- Edited after the pointers from the comments: * Everyone can own brooms. * All the other modes of transport (which are currently available, would be available) * The world is just as normal as the present world. Modern day airplanes are not available. The state-of-the-art air travel at that time are [Zeppelins](https://en.wikipedia.org/wiki/Zeppelin) * Characteristics of the broom: high speeds(similar to that of an average family car) and are difficult to control at high altitudes * Brooms are made of wood. * No witches. All are normal people. Just that, it is a world where a broom is another mode of travel [Answer] You may find more people taking cars than you expect. Consider that your broom reminds me lot of a motorcycle. Very fast, no crash zones, and very bad consequences when you do finally hit the pavement. Accordingly, you may find that broom travel is about as popular as motorcycles are today (about 2.2%), decreasing your traffic issues by about 40 fold. I would expect to see, at a minimum, the current air traffic approach of using altitude to separate lanes of traffic. One might seek to create a altitude mapping such that you are guaranteed to have 100 vertical feet between individuals going in opposite directions. If you made this mapping smooth, you could ensure we don't see very many dangerous crashes because most interacting individuals were all traveling in the same direction. As an added bonus, the only legal way to get to your "lane" to go to work would be to spiral upwards, constantly going the "correct" direction for each altitude. I'd think seeing a broom-wielder spiraling upwards cackling maniacally at the poor gridlocked cars below would fit well with the mythos associated with other broom wielders. [Answer] It would be grim. First of all, there would be lots of deaths and severe injuries due to falls, midair collisions in crowded downtown areas, and also countless cases of frostbite due to moving through cold air at high speeds. Public outrage over the mounting number of victims would steadily climb. Eventually someone would design a glass or plastic windshield, some more comfortable and safer seating (who wants to sit on a long hard stick after all?), better handles to grip and help direct the darn thing, a little screen for GPS, a warming element, windshield wipers, headlights and signaling lights, more seating, a luggage compartment, fly-by-wire steering, automated radio broomtraffic control with computers allocating aerial microcorridors to the millions of broomcar commuters, on-windshield heads-up-displays for easing the hurdle of staying within one's allocated air corridor, automated collision avoidance software for when you veer out of it anyway, airbags and parachute packs for when that too fails... ...Until a few years later it would look like a bladeless helicopter. Eventually, the rich would buy broomcars with 50 broom assemblages that can provide enough magical thrust to quickly launch one into outer space. [Answer] I am looking at this problem professionally ... the problem is basically 3D traffic management. There are two basic examples in use today on earth. the Air space controller system for aircraft. and flocks of birds. There would have to be flight pathways and rules established and training as we have in air traffic control. minimum transit altitudes, restricted areas, would have to be marked either as flashing restrictions or electronic highways. in general slower traffic would be at lower altitudes. Birds navigate independently and as a group, with communication. Geese are a prime example. They take turns, leading a formation. this probably will not work with humans ... too many cowboys. Transponders, and navigation indicators, red= port or left and green= right or starboard. would be an absolute must and traveling with it off must be a serious crime and with serious punishment. violating the rules should result in suspended flight 'privileges'. [Answer] Governments would build infrastructure to support it. In the same way that we allow people to drive 2 ton vehicles with minimal training and minimal local communication on marked roads, broom drivers would be given similar treatment. As long as everyone follows the rules, then there need be no additional communication. For instance, you might have 25 foot or 8 meter height divisions. At 0-25 feet you are to travel no faster than 15mph (24kmh) to facilitate landing and takeoff from any location. At 25-50 feet you can only travel within 22.5 degrees of north, at 50-75 north west, 75-100 west, and so forth. To launch you always start north, and then accelerate in a circle as you ascend to the direction you want to travel, and these initial lanes are fairly low speed. Higher lanes are similarly broken up, but with much higher speeds and much more space between differing directions to avoid accidents with people traveling in opposite directions. Minimum speeds will be necessary in all cases, because sight lines won't be very good and a fast moving broom could overtake a slower moving broom too quickly to avoid an accident. In lighting isn't available, hand signals or simply body positions could be enough. Leaning back to slow, forward to accelerate, tipping the head one way or the other and up and down to indicate a turn and ascending or descending. Markings on the ground could provide further special notices, lanes, etc. For instance there may be a special height that tracks into the city center in the morning that changes into a track going out of the city center. If you're at that height you need to be aware of the time, and you can only travel directly toward the city, regardless of your current location, during certain times, then cannot use it during a switchover time, then must only use it to travel directly away from the city in the evening. [Answer] Must have - windshield. I have eaten beetles and ants, and believe me, it ain't no picnic. You do not want to be eating (or wearing) that many bugs on your way to a dentist appointment. Also a must have - altimeter and computer controlled altitude. The computer controlled altitude is government regulated. The computer calculates the altitude as a formula of direction (degrees from true North) and speed, to maintain safe flight altitudes so people going in the same direction and speed are all travelling at the same altitude. But hackers make a business of bypassing the regulated controls so people can do drag-races down the Grand Canyon, or the Redwood Forest or downtown New York. [Answer] I'm going to make a couple assumptions: * Despite being able to fly, brooms have a capacity similar to bicycles * Brooms are a popular enough option to warrant some traffic regulation * People, for the most part, transport stuff safely, the rest being negligible Initially brooms would have no regulation since their numbers wouldn't warrant it. After reaching or approaching the point where collisions are a more common concern they probably would adopt the existing regulation for horses, carriages, or cars, similar to how cars share the road with bikers. People would still operate outside the rules now and then, like jaywalking or biking through a park or parking lot as a shortcut, broomriders might skip over a block diagonally, and it would probably receive a bit more attention than its counterparts because of the increase in speed and hazarding. If society were green, then yes there would definitely be campaigns promoting broomriding as a green form of transportation. ]
[Question] [ **Closed**. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Add details and clarify the problem by [editing this post](/posts/4034/edit). Closed 9 years ago. [Improve this question](/posts/4034/edit) I'm trying to design a world in which (for the storyline) magic has evolved along with technology (ideally at a somewhat equal rate if this sounds coherent but I'm flexible) until the world has reached today's technology (and an equivalent advancement in magic). I'm assuming it takes research, skill, time, luck and practice to advance in both domains. What should I consider when designing such magic and such society? *I'm not asking for a solution, just for the right questions to bear in mind, the right things to think about*. I like having coherent worlds, as close as possible to a science-based fiction. [Answer] In short, Economics. A world with both magic and science will utilize the most efficient (fastest and/or cheapest) methods of mining, production, etc. So if a forklift (fuel costs, materials to build, training) are more expensive then someone with a "high school" level of telekinesis; why would any company use forklifts? This may not be 100% true across all industries but it would certainly be the normal procedure; many sword smiths now use modern steel and techniques but some traditional sword smiths still craft things the old fashioned way to preserve traditions and techniques. In such a way some difficult things to achieve with magic will still be practiced for the challenge or achievement; but not on global or industrial scale. Further since economics is easy to calculate for modern industry/science (material cost + fuel or energy + maintenance) magic would need to be similarly comparable in a "dollars and cents" kind of way. Operate a forklift for 8 hours = 20 dollars of fuel, reduces the "expected life" by 1% at the cost of the machine of 1000 dollars = 10 dollars, and a maintenance cost of 1 dollars is a total of 31 dollars. Does the magic have material components that add up to equivalent costs? Castings times? A forklift can just "work" for 8 hours if the spell takes 1 hour to cast and then lasts for 7 hours you're doing slightly less work. [Answer] The first thing is that you need to know what magic is, quite precisely - if you're going mix it up with technology then it needs to have a clear and limited definition. Some good examples of this might be the ones you see in Patrick Rothfuss or Brandon Sanderson's writing, where magic is governed by clear and understandable rules. Even if those are never made explicit within the setting, you need to know what they are for yourself. A consequence of this is that you also need to have a reason that magic is not simply "sufficiently advanced technology" - what marks it out as *different* from regular technological development? Perhaps only some people have the ability to do it, or magic is governed by some kind of sentience that must be bargained with or similar, but you need to have a reason that magic isn't simply a different energy source you can use as a battery for your mobile phone. **Doing the sums** One of the biggest changes in the development of technology in the real world has been that our understanding of mathematics has allowed us to develop new tools for exploring the physical world- in particular from Newton forward, most technological advances have some kind of mathematical underpinnings. This might be a reason for magic and technology to evolve at a similar rate- assuming both are - to some extent - natural processes, similar mathematical tools are likely to be useful for exploring both. **Collision of ideas** Often what mark out a major technological step is a new idea or concept that nobody had thought to implement before. In a world where magic and technology intermingle, you have two spaces for those concepts to arise and when one emerges in either field, you might expect that the other would find ways to replicate the concept or perhaps to extend it. That spirit of replication and competition could spur a lot of interesting development. As a corollary, it might be interesting to make different things simple with either, so things that are easy with magic are technologically hard and vice versa; maybe magic can create clear three dimensional images, but moving a heavy load between two places is *really hard*. **People are important** Whatever your narrative, the thing that will draw an audience in to the setting will be how people react to the conflict/complement of magic and technology. Think about how this divergence affects society- does the existence of magic divide or unite people? Does it get caught up in religion or other mass social movements? Do people take it for granted or find it to be extraordinary? The way that people respond to and use both technology and magic gives you a lot of open doors for setting up interesting stories. [Answer] The biggest deciding factor in how much magic affects technology is what kind of magic you have. Here are a few questions to narrow that down: * How available is magic? + If magic is available to everyone, technology simply won't exist in the areas that magic covers. If you can magically clean your windows, why would you buy window cleaners? + If magic is available only to a very select few, then technology may progress normally, since the impact of magic on the world is relatively low. In both the Harry Potter books and in "Star Wars", the number of magic users is low and/or hidden, so the impact on technology is minimal. + If magic is widely available, but very difficult to use, it will likely have little effect on technology, since anything powerful enough to replace technology would only be available to a select few. Of course, if those select few have god-like powers, it may be that they replace technology themselves. * How does magic interact with technology? + If magic makes technology fail, then magic and technology will never work together. An example is the Dresden Files series; technology around wizards tends to go up in clouds of smoke and a shower of sparks. That would result in a rift between magic and technology, and whichever group was bigger would force the other down, either through politics or force. * Where does magic come from? + If magic comes directly from magic users and cannot be stored, then it is slightly possible to tie magic and technology together. For example, the "bending" in the television show "The Legend of Korra" could be considered magic; one episode shows fire benders creating electricity for a power plant. + If magic can be stored in runes or used to create artifacts, it is possible that technology could be driven ahead rapidly, since technology could use the magical energy to power itself and to 'cheat' at technical limitations. It's completely possible for technology in that world to use 'magic batteries', magic runes that can be easily replaced as the power is used up. * How is magic used? + If magic is driven and powered solely by imagination, technology will be of little use to an imaginative user, since anything they could think to invent could already be done with magic. If there are enough imaginative people, or if schools teach how to productively use magic, then technology as we know it won't exist, as it can be completely replaced by magic. + If magic is driven by logical, immutable rules, then technology can coexist, or even be improved by magic; if it interacts with the physical world the same way every time, it can be used as a platform to build better technology. * Finally, how does magic manifest? + Magic composed of energy, like fire, force, electricity, or light could fit well with technology; as previously mentioned, powering electrical plants with magic. + Magic based on the mind or spirit world (mind control, soul-eating, possession, etc.) would not interact with technology much, except to inspire inventions to detect, counteract, or duplicate its effects. + Magic based on creating, destroying, transmuting, or transporting matter would have a huge effect on technology. Being able to transmute lead into gold would mean technology would never be at a loss for materials; being able to dig a strong tunnel with magic would mean transportation could grow by leaps and bounds. + Magically transmitting or generating sights and sounds (veils, hallucinations, crystal-ball-gazing) would probably not have much impact on technology, unless it was widespread and repeatable enough to replace televisions or radios. + Magic that interacts with time (seeing the future or possible future, or time travel) could have a huge impact on technology, either for or against it. If it was possible to look into the future to see which of experiment works, you wouldn't have to spend money or time to actually do those experiments, and instead could cut directly to production. On the other hand, happy accidents would be much less likely to happen, since accidents in general would be much less likely to happen. [Answer] > > It might be helpful to frame this question in terms of how your > world's secondary schools might teach several subjects differently > from our own: > > > **Science** We've all heard Clarke's maxim that "any sufficiently advanced technology is indistinguishable from magic," so how would people in a merged world teach magic? If it's a fundamental law of nature, why wouldn't it be taught in science class? How would it be taught? It's not pseudoscience if it's real. Would "divination" be included in the scientific method? **History** If one of the magical abilities present in your world is the ability to read or control minds, then the nature of history becomes difficult. If the Archvizier of Dunlop suddenly became a murderous despot in 1277, who's to say that she wasn't brainwashed to aid her cousin's coup later that year? Maybe her cousin wasn't the saint she's always been portrayed as. Think of all the crazy crackpot historical theories in our world - Bigfoot, the Chupacabra, the Illuminati - and realize that in your world, *they're all possible.* **Mathematics** On the face of it, this would seem to be the same in your merged world as it is in ours, but if a divination spell can instantly prove any theorem or solve any algorithm, why would complex mathematics such as calculus have ever emerged? However, if there is an "arithmancy" that governs magical work, the line between science and magic begins to blur and the two might aid one another. **Economics** As other answers have noted, the economics of such a world would be vastly different than our own. If something is cheaper when done magically, the scientific supply of that good or service will dry up. However, if science does something cheaper than the magical equivalent, what happens to the person who can perform that service inherently? For instance, if scientific transportation is cheaper than magical teleportation, what happens to the people who have the magical ability to teleport others through space? Do they ply their trade to the wealthy, or do they try to earn money by other means? **Technology** *"ilinamorato, that's silly,"* you say, *"this question is ABOUT technology!"* But hear me out. Cheap conjuration of basic objects would mean that mass manufacturing never developed, so other forces would have to have driven scientific development. We might see a much earlier development of digital information systems. Conversely, if magical conjuration could be applied to the manufacturing process, you might find yourself in a world with far cheaper, more quality-built manufactured objects. **Literature** In such a world, science fiction and fantasy would not be a pseudo-subcultural genre, but a genre that encompassed their everyday lives. So what would "genre fiction" be like? Do nerds read books about life in a magicless world - our world? **Foreign Language** If the magic in your world allows for quick travel to distant lands, foreign language will be a much more important class to take. If it allows for time travel, the dead languages of the past and uninvented languages of the future must be considered. You wouldn't want to offend your future self. **Health** Don't think that just because magical spells can heal injuries and diseases that health won't be a concern. Think about the processes that will be accepted in this world that might be considered homeopathy or witch doctoring in our world. Medicine will likely be a partnership between the magical and scientific, with much of the diagnostic work in the scientific realm while treatments are conducted by the mage. How will their interaction be? Will it be like in the TV show *Scrubs*, where surgeons and internal medicine doctors are often at odds? Will hospitals include altars for sacrifices and incantations? **Biology** Do humans integrate technology into their bodies? Do they try to select for magical attributes in their offspring? Do magical creatures such as griffins and dragons exist in this world? Is there a demihuman race such as dwarves in this world? **Sociology** Does everyone integrate both magic and technology into their lives, or are there "technologists" and "magicists", neither of whom trust the other? Is technology considered "old fashioned," used only by hipsters and grandparents who are hopelessly out of touch with the new generation? **Politics and Government** How will the politics of this blended world work themselves out? Are the mages governed by a different body than the scientists? How does a government prevent magical tampering with elections? Are officials even elected, or does a diviner simply cast spells to discover who the people want to be elected, or who would be better to rule? How do different nations interact with one another? Is magic more prevalent in one country than another? Can magical power make a country a superpower? **Physical Education** Is there a sport that consumes the world (like football, or maybe football)? Is it scientific or magical? Is it considered poor sportsmanship to use magic in sports, or is it considered "just part of the game"? **Art and Music** This probably wouldn't be much different in the blended world than in ours, but it is worth thinking about how the arts in a magical world would look. **Criminal Justice** Clearly a magical criminal could do a lot of damage. But so could a technologically-advanced criminal. How does the police in this world fight crime? Is it an alliance between mages and techies, or is there a Magic Police and a Science Police? How does one report an emergency situation? In what manner do the magical police arrive? ***Some short thoughts:*** **Meteorology:** Will controlling the weather be as much the domain of meteorologists as predicting it? **Astronomy:** Is Astrology part of this science? **Philosophy and Ethics:** What is right and wrong in a world where anything is possible? **Agriculture:** How is food created/grown? **Communications:** How are messages transmitted? > > *Obviously* you don't have to have an answer for every question. But as you're developing your world, it would be helpful for you to be > able to answer most of the big ones, so that when the little ones come > up you can make a decision based in the lore you've already > established. > > > [Answer] I think the main point to consider is making neither magic nor technology absolutely superior to the other. If magic is always the much better solution, then technology won't be used, and vice versa. Ideally, magic and technology both have areas where they are better suited to the problem than the other. For example, you could have magic being at advantage for healing (and thus having a magic-based medicine with very little technology) but technology being at advantage in transportation (so that transportation will be done using technology, and magic transportation, if possible at all, is only used in exceptional circumstances). There could also be fields that need both magic and technology (for example, you could use magic to let a production machine withstand forces which no material could otherwise withstand, but the production process itself is just a technological one that however couldn't work if the machine could not withstand those forces). There could also have been a rivalry and competition between magic and technology which made both sides improve their abilities as much as possible to stay competitive, causing as a side effect a quite rapid development of both magic and science. For such a competition, it would probably be a good idea if it would be hard, if not impossible, for a single human to be both good in technology and good in magic. [Answer] I'd imagine it like a biological arms-race where for example the prey (magic users) would compete against the predator (tech users). This example is straight out of the avatar anime series. Roles may be different in your imagination. The main idea is that whenever someone with magic usage is able to perform extraordinary talent and make a living out of it, someone will come up with a technology of similar effect in order to compete in wealth and in lifestyle. This scenario would be suitable for a society where magic usage and technology balances out perfectly. If there are few casters, you may have to re-design the society, making the magic users obsolete and archaic and perhaps even feared. (idea is from the sword of truth book series by terry goodkind) In a scenario where technology users are rare and secretive, you may have to re-design the society giving tech users ways of survival and/or acceptance. No such work of fantasy comes to my mind. Perhaps someone could make a more complete list. [Answer] I was going to comment on [Culyx's answer](https://worldbuilding.stackexchange.com/a/4038/2113), but it was getting too long. Another question related to this is how rare the magic is. If one in ten people is capable of nearly free telekinesis, then the magic solution will dominate. If there's only one person in the world with the telekinetic ability to replace a forklift, forklifts will be the typical solution. Given the story parameters, I would think that the goal would be to balance them such that both are used. So forklift-replacement telekinetics should be maybe half as common as forklifts are in our world. That should make it so that people choose forklifts about half the time. That way, the technology group takes the trouble to develop forklifts while still substituting magic for them somewhat frequently. You also may want to make magic talent somewhat uneven. For example, if this were an Earth-like world, you might make magic common in sub-Saharan Africa, Australia, and the Americas but uncommon in Europe, Northern Africa, and Asia. So the nations that we think of as developed in the real world have to use technological solutions while the nations that we think of as part of the third-world use magical solutions. Probably less colonization in this world though. That way, the combinations would mostly be relatively new while the traditional solutions would be mostly technological or magical rather than both. If you do not do that, then you'll have to find another reason why technology advanced as much as it did. You'd think that magic would naturally substitute otherwise. So technology would be primitive in some areas while potentially advanced in others. ]
[Question] [ It's a pretty simple question: imagine you have a solar system about the same size as our current one. This solar system is close enough to nearby colonies that most observatories can see the planets in the system but not so close that they would be wiped out as well. I'd ballpark the distance to be about a light week or two, but that is a completely random and unscientific number, so any distance that would make the system visible but not dangerous to others is fine. There are also plenty of supply runs and probes and other forms of data entering and exiting the solar system. And yet, with almost no warning, the solar system is destroyed. This could be in the form of an actual explosion, supernovas, antimatter, anything based on science. The problem is, astronomers could easily see most space events ahead of time, events that usually take a long time to react. **So, what kind of scientific phenomena would wipe out an entire solar system with almost no warning?** * Bonus points if the system becomes dangerous/uninhabitable post-catastrophe * Double bonus points if the system becomes unsalvageable post-catastrophe (no metals can be mined, the system has completely gone away) Clarifications: Destroyed means the entire system is obliterated like the planets are rumble. The unsalvageable bonus part is if that rumble is basically only atoms or something that other colonies could not harvest for themselves. [Answer] # Gamma Ray Burst A nearby GRB manages to dead-center the solar system with one of its polar jets. This jet of energy contains the energy output of a typical star's entire 10-billion-year lifespan, focused along two polar jets. The Jets are quite directional, as narrow as just 2 degrees wide. Each contains something like 10e44 Joule, enough to vaporize a planet several billion times over. The planets in the system are literally vaporized. In addition , the star is overheated and busy trying the Red Giant fashion style. [Answer] ## Star Lifting Gone Wrong There are very few natural phenomena that are big enough to wipe out a solar system, but also small enough to not kill everyone just a few light weeks away. The only real candidate for this would probably be a [nova](https://en.wikipedia.org/wiki/Nova) (not to be confused with a supernova). Smaller novas can cause a star to flare up its energy output somewhere in the range of 8 orders of magnitude when they happen. If you were to imagine the Sun suddenly getting a few million times as bright as it is right now for a few days, you can easily imagine all planets in the solar getting scorched to a crisp, but a few light weeks out being fine. The problem with these is that it's very easy to detect a star cluster that is at risk for this type of event, and such stars tend to have nova at intervals too close together to even allow life to get much of a foot hold around them, and they are recognizable by having white dwarves at very close proximity to a main sequence or red giant star... so you'd never end up near one by accident. But, perhaps your people did not evolve around this star, but colonized it specifically because it has a closely orbiting white dwarf/main sequence star pair. Their goal could be to try to interrupt the pattern of Novas while harnessing the matter stream between the white dwarf and main sequence star as a sort of star mining program. By harvesting this stream they could collect enough raw matter and hydrogen fuel to build and power massive Megastructures like Dyson Spheres and/or more star lifting platforms. But something went wrong... The mega structure that is supposed to be held in gravitational equilibrium between the star and the dwarf drifts a little to far and starts to fall towards the dwarf. Because the stars are so close together, it is only a matter of days, maybe even hours before the station containing billions of billions of tons of stockpiled mass crashes down into the white dwarf and all that hydrogen atmosphere that it normally takes years building up is introduced all at once. The mass of the star lifting station triggers the nova event that the station was designed to prevent. Because communications only travel at lightspeed, by the time the colonists get the message that the station is falling into the dwarf star, it will have already happened. All they can do is watch and wait for the inevitable flash of light. While this is not exactly instant, it's probably the closest you will get barring any sort of intentionally activated weapons of mass destruction. [Answer] When you get to the scale of "wiping out solar systems" there aren't many phenomena capable of producing power on the insane levels we're talking about. The most likely option is to have a rogue black hole hurtle through the system and rip it apart. Detecting a rogue black hole might be incredibly difficult, as the only thing you can see is the distortion as it passes in front of background stars. The tech level require for inter-stellar colonies almost surely allows for constant monitoring of every visible star, but with a bit of "luck" a rogue black hole could slip by until it was too late to do anything. What exactly would happen to a solar system that collides with a rogue black hole depends on a large number of factors. Planetary and stellar bodies rarely collide directly though. So to have the planets of this solar system "completely gone", the best bet would be for them to be ejected VERY violently from the solar system by the gravity of the passing black hole. You could also have the planets redirected into the star or black hole which would surely destroy them but is probably less likely than simple ejecting. [Answer] # Strangelet [Strangelets](https://en.wikipedia.org/wiki/Strangelet) are fragments of matter made of [strange matter](https://en.wikipedia.org/wiki/Strange_matter). I.E. matter composed by roughly equal numbers of up, down and strange quarks. So, the alien civilization is running an experiment for generating a high-density fuel by exploring the energetic possibilities of [quark-gluon plasma](https://en.wikipedia.org/wiki/Quark%E2%80%93gluon_plasma). The strange\* experiment needs copious amount of power, so they build it into a huge space station in an orbit very close to the star in order to be able to cheaply collect large amounts of solar light. But then, something strange\* happens. Something went really, really very wrong! The station explodes and a large core of strange matter (I.E., a strangelet) is thrown at relativistic speeds directly into the star. The [strangelet quickly converts the star into strange matter](https://en.wikipedia.org/wiki/Strangelet#Dangers), turning it suddenly a [quark star](https://en.wikipedia.org/wiki/Quark_star) or more precisely, a [strange star](https://en.wikipedia.org/wiki/Strange_star). Of course, the process of suddenly turning a main sequence star into a strange star, especially one that is completely uncontrolled and starts very assymetrically in the star, happens in a chaotically messy way and severely disrupts the star's structure. The result is that actually, not the entirety of the star is converted to a strange star, but some large parts of it are actually energetically ejected at relativistic velocities all at once. I.E., it blows up spectacularly into a very strange\* type of supernova. We need to consider that [if you observe a supernova from 1 AU of distance, you will see it as a billion times brighter than the detonation of an hydrogen bomb pressed directly to your eyeball](https://what-if.xkcd.com/73/). This means that any planets in orbit will be quickly incinerated, vaporized and turned into a plasma. What a strange\* game over! \* pun intended [Answer] # Relativistic Jets Crossing the path of a relativistic jet could destroy a system with little to no warning. As a black hole rotates, ionized matter gets pushed to the poles and fired off in a long stream. The faster the black hole spins, the greater the jet velocity. Spin fast enough and these streams approach the speed of light. The beams are strongly directional and have a diameter initially the same size as the black hole, though they spread wider over distance. <https://en.wikipedia.org/wiki/Astrophysical_jet> These jets would both ionize and physically pulverize a solar system that crossed the path. Because of complex orbits, it is possible for a system to be in the path of a beam for just a moment or for extended duration. Because the beam is highly directional and moving at near speed of light, it may be impossible to have any early warning depending upon the angle of approach to the beam (closer to right-angle approach means less time in the penumbra of the beam so less warning). The jet could be coming from any black hole, even well outside our galaxy — there’s no way to monitor for all of them. Leave the system in the beam for a short time and you have lifeless place with heavy radiation poisoning and lots of cratering. Leave it in the beam for longer time and you have planets physically etched and broken by speed-of-light machine gun spray of bullets impacting entire surface with explosive impact. [Answer] # An Alcubierre hiccup Either due to an engineering mess-up or just spatial anomalies fluctuating into being, the star and its closer planets were warped in a certain direction, whereafter they were either destroyed during the process or due to where they were warped to. You could have a known black hole in the area, for example, maybe it sucked on the edge of the space warp and then ate the star and planets. Or maybe the system was warped into a larger star, or whatever. # A local Rip For some reason, the local expansion of space increased drastically enough to Rip all local structures apart. Since the metric inside the area would go to infinity, maybe from the outside the excitations of the field would be infinitely diffused, so anything resembling remnant matter moving towards far-enough-away colonies/outposts would be vaporous enough not to damage those colonies/outposts on impact? But you still might get an effect like [when that one guy put his head in a particle accelerator](https://en.wikipedia.org/wiki/Anatoli_Bugorski)... [Answer] I'll just quickly throw my hat in here. There is a part of quantum field theory that describes something called a "false quantum vacuum". How it works exactly is complicated, but the theoretical end result is a local or universal cessation of action from the fundamental forces, causing the absolute destruction of matter. As per it is a probabilistic function of the quantum field, it can basically happen absolutely spontaneously. Physicists calculating the probability believe it to be extremely unlikely, and the scale of destruction is usually described on a universal scale, but this would be an occurrence with absolutely no warning and complete devastation. [Answer] No boom can make this happen. You're talking about planets, "reduced to rubble" doesn't make much sense. By very definition planets aren't held together structurally (the definition requires them to be round due to gravity--thus gravity has overcome any structure.) They're held together by gravity, the only approximation I can see for "reduced to rubble" is more energy is applied than the gravitational binding energy of the planet, thus throwing the bits to infinity. Anything less and the planet reforms. Ok, the outermost planet is Neptune. It's gravitational binding energy is 1.7E34 Joules. It orbits 4.17 light hours out. Uranus has a cross section of about 1.9E15 square meters. That means the energy density at Neptune's orbit must be at least 9E18 J/m^2. Your observers are a light-week out, 40x as far. Thus they get 1/1600 the energy density. Thus the observers are hit with 5.6E15 J/m^2. You can make a ballpark approximation of the energy involved by covering the entire star-facing side of your observation platform with hydrogen bombs. (You're looking at 1.3 megatons per square meter.) The only way you are going to deliver this kind of energy is a beam from elsewhere. Gamma ray bursters have already been mentioned but I do not think they come close to the energy density needed. If you will accept a different way of wiping things out, the rogue black hole approach will do it. Playing with Universe Sandbox I was able to completely denude the sun with a close flyby with a 10 solar mass black hole, although some planets were captured by the black hole. I suspect a somewhat smaller one would have done it, but the editor leaves something to be desired, I'm not going to run a bunch of tests. If it doesn't get close to the inner system it can't rip off the inner planets. A poorly aimed 100 solar mass black hole left the inner three, albeit I don't think Earth was still inhabitable. [Answer] A wandering black hole, or a black hole made in a lab gets loose. If it crashed into the star, the star could nova. People on the colony are encouraged to wear sunblock. Planets are disrupted in their orbits and destroyed, or perhaps begin an unstoppable fall towards the star, joining an accretion (?) disk. It might be a long time before they contact the event horizon but the resources are as good as gone. [Answer] **A Descendant of Ernst Stavros Blofeld, famed nemesis of super-spy James Bond, was shooting pool one day with some friends when he uttered the most terrifying phrase in human history... "Here, hold my beer."** What happened next stunned half a galaxy — which was fine with Amaranthos Ophiouchos Blofeld, who loves to be the center of attention. You see, what he did was hold the Capella star system1 ransom! What he didn't count on was the reigning oligarch, *His Excellency, President for Life, Field Marshal and Doctor Rhamadahaman, Lord of All the Beasts of the Earth and Fishes of the Seas and Conqueror of the Aldeberan Empire and Cygnus Minor in Particular,2* calling his bluff. ***Nobody calls a Blofeld's bluff!*** You see, a week before he'd been reading this historical article from [Space.com](https://www.space.com/lava-flows-earth-magnetic-field-reversal.html) where he learned... > > The reversals take place when iron molecules in Earth's spinning outer core start going in the opposite direction as other iron molecules around them. As their numbers grow, these molecules offset the magnetic field in Earth's core. (If this were to happen today, it would render compasses useless as the needle would swing from pointing towards the north pole to pointing to the south.)During this process, Earth's magnetic field, which protects the planet from hot sun particles and solar radiation, becomes weaker. > > > > > And that gave him an idea, what if he could play enough merry havoc with the molten iron in the core of every planet in the Capella star system that had a molten iron core just long enough, oh, maybe a couple of hours or so, to let the amazing solar maelstrom caused by [four stars](https://en.wikipedia.org/wiki/Capella) to gently barbecue the snot out of each planet? **Buahahahahahaha!** You see, what's happening here is that a planet's magnetosphere is created by the planetary liquid core, and it affects the planetary liquid core. In the case of Earth (which we will egregiously extend to all planets enjoying a liquid core), the inner core and outer core spin in different directions. > > "Previously, there have been these two independent observations, and there has not been a link between them," study co-author Philip Livermore, of the University of Leeds, told LiveScience's OurAmazingPlanet. "We argue that the magnetic field itself is pushing on the outer core, and there is an equal and opposite push on the inner core." ([Source](https://www.livescience.com/39780-magnetic-field-pushes-earth-core.html)) > > > What this means is that all one need to do to get the poles to flip (or, better yet, to *almost flip*) is to change the rotational speed of one of the cores (inner or outer) such that the compounded effect from the magnetosphere would be to create a *metastable condition.3* In [true Hollywood fashion](https://en.wikipedia.org/wiki/The_Core), what we're trying to do is get the engine that creates the magnetosphere to stall... just for the proverbial second! Amaranthos is convinced that one way to do this (one not previously considered by the greater scientific community)4 would be to change the rotational speed of one of the two cores. It doesn't matter which one, and it doesn't matter how much so long that it's enough to destabilize the balance between the two core rotations and the magnetosphere. Frankly, if you noted the progression of one of the poles, you probably could work out where to apply pressure to get it to move *just a little bit more....* From a very simplistic point of view, it's like changing the gearing between a motor, a flywheel, and the load connected to the flywheel. If you rapidly and dramatically change the balance of energy, the system attempts to compensate — and the result can be spectacularly violent. How did Amaranthos plan to do this? ***In true Blofeld style!*** He realized that he could sneak the millions of nuclear weapons needed to superheat the outer core of each planet (because hot things move faster, right? And it's so much simpler to heat things up...) into place without attracting anywhere near the attention that such an action would normally deserve. All he had to do was `[Redacted for national security reasons]` and when the Prefect of Greffetacle heard about it, he actually laughed out loud! So, when old Rhamadahaman sent Amaranthos a text and called him an overrated blowhard good for nothing more than the entertainment of his troops... well, naturally, Amaranthos pushed the button. And when the magnetosphere collapsed on all those planets, they were snuffed out, cooked to a crisp, and left irradiated for generations. As Blofeld said when he reclaimed his beer, "I pity the fool who tries to mine on one of those planets!" --- 1 *The planets are there. I'm sure of it. You just need to look harder! Try squinting....* 2 *With all due respect to Idi Amin Dada Oumee, who never let common sense stand in the way of first-class title mongering.* 3 *A fancy way of saying, "a moment where the darn planet doesn't really know what it wants to do."* 4 *Did he forget to add "scientific god among men" to his title? I'm sure I left him a note to add it. I'll get right on that.* ]
[Question] [ In my story there is a mountain range which is almost impossible to climb because it is very steep, and it has a very, very loose surface. Wherever you put your foot, the ground is liable to slip away beneath you. It has no soil. Ideally, it would also be volcanic. Could such a mountain form on an Earth-like planet? What kind of process could produce it? What other geological features would or would not be associated with such a structure? [Answer] ***Cinder Cones:*** I'm not a geologist, but most true mountains are going to have hard surfaces because these hold together - they may be too steep to climb, but that's a separate issue. Materials that are loose come apart easily under erosion, and are not going to last for very long. So you need a geological structure that is ***very*** new. So how about a very recent eruption? I would suggest a volcanic structure like a [cinder cone](https://en.wikipedia.org/wiki/Cinder_cone). Small bits of volcanic ejecta pile up as they are spewed out. Volcanoes also spew out vast quantities of ash, which is usually quite slippery, and this ash covers the landscape, choking out plants that tend to lock down the surfaces. Now the landscape is covered with piles of tiny bits of lava, pumice, and ash, and plants that would offer a handhold are buried. Even a regular mountain nearby might be covered in a layer of loose powder after an eruption. Soil is covered and offers no help. [Answer] For an earth like planet, such a mountain is not likely. The dominant factor for your mountain of grit is termed the [angle of repose](https://en.wikipedia.org/wiki/Angle_of_repose) and its the reason that you can't pile sand up into a column. It will always fall down into a pile -- absent additional forces like freezing water or sticky binders like tree sap. Lose materials will always slide into a pile unless they have a stackable shape -- like a cube. The coefficient of static friction reflects the shape of the grains and their inherent stiction -- tendency to bind and clump together $$ tan(\theta) == u\_s $$ Where $u\_s$ is the coefficient for static friction of the material that has been piled up. Listed below is a table of typical angle of repose for different materials. [![values for angle of repose for different materials](https://i.stack.imgur.com/7kvIB.png)](https://i.stack.imgur.com/7kvIB.png) [Answer] I remember well the last big San Fransisco earthquake in 1989. There were a lot of collapsed buildings and structures. At first, the engineers and soil engineers were baffled. The soil was a thick, heavy, solid sand-clay. It had been compacted to what they had thought was its maximum compaction, over time. The heaviest of buildings, built upon it, just didn't sink. It had a very high load factor. In fact, when digging foundations, you could dig at pretty much a 90 deree angle slope side wall, for quite a depth, without the soil collapsing. Almost as steep and stable as a rock slope. Yet, many very solid buildings actually sank and tilted in the soil. What they found, after some experimentation, was that under the high frequency of the shaking during the earthquake, the soil [essentially liquified](https://www.swri.org/technology-today/liquefaction-consortium-earthquake-models). The buildings were no longer on a solid footing, they were in quicksand. So, in fact, you can have a very stable mountain with a fairly steep slope, as long as you have some mechanism by which the footsteps of the humans create a very high frequency local vibration. How you produce this effect, is a seperate issue. Perhaps there is something about the metabolism of your inhabitants that cause them to shake constantly and violently, like a hummingbird must vibrate. Thus, the mountain would remain stable up until they tried to climb it. Then, it would turn as slippery as slushy water, but only where their footsteps landed. See [this](https://www.britannica.com/science/soil-liquefaction) reference for a description of soils that are mose susceptible. > > Poorly drained fine-grained soils such as sandy, silty, and gravelly > soils are the most susceptible to liquefaction. > > > [Here](https://www.britannica.com/science/soil-liquefaction) is a link to liquefecation of clayey soils, that can cause landslides. > > Research was conducted on artificial clay–sand mixtures and natural > clayey soils collected from the sliding surfaces of earthquake-induced > landslides. > > > For the artificial clay–sand mixtures, it was found that the presence > of a small amount of bentonite (≤ 7%) would cause rapid liquefaction, > while a further increase in bentonite content (≥ 11%) produced the > opposite effect of raising soil resistance to liquefaction by a > significant degree. It was demonstrated that the bentonite–sand > mixture was considerably more resistant to liquefaction than the > kaolin-, and illite-mixtures, given the same clay content. The test > results of plastic soils revealed the significant influence of > plasticity on the liquefaction resistance of soil. > > > [Answer] Optionn number two. **An ice mountain** Fed by precipitation at the peak, it is one big icicle. Definitely in the 'nortern climes', during a global ice age. However, it is covered by lichen to a substabntial depth, that are hard to scrape off, forming a tough coating over the mountain. The lichen get their water from the ice surface, and the sun coincidentally happens to be quite bright. The lichen act as a thick insulating blanket over the mountain, keeping the inside cold. The lichen use the water and gases in the atmosphere to produce a slushy slime-like residue, that coats the external surface completely. This slush is extremely slippery, too slipery to offer any kind of grip for a climber. And when they lose their grip, it is slip-and-slide all the way to the bottom. An option: rather than a volcano, add steam vents traversing the mountain. The ice would be so thick, the steam would not be able to melt the entire mountain, just etch channels through it. No lava, just a flow of icey slush that soon freezes and solidifies every time the steam erupts. The nutrients carried by the steam from the inner voids of the planet could also feed the lichen. You have your mountain, not made of soil, that is too slippery to climb. [Answer] While it would be unlikely to have a whole mountain range like this, there are mountains with localized areas that fit the description. For instance, the east slope of the Sierra Nevada in the vicinity of Lake Tahoe. Several of the mountains have steep east faces that are mostly decomposed granite (essentially coarse sand), which is pretty well impossible to climb. (But slopes are much shallower and composed of rock & vegetated soil when coming from the west.) The white areas on the slopes in these pictures are the decomposed granite. <https://en.wikipedia.org/wiki/Slide_Mountain_(Nevada)> <https://en.wikipedia.org/wiki/Jobs_Peak> Geologically this is because the range is a slab being tilted up on the eastern side, along faults (e.g. the Genoa fault: <http://www.nbmg.unr.edu/_docs/Newsletters/nl14a.htm> ) that is quite visible in some spots along the base. The scant rainfall in the region means that the loose surface isn't washed away. [Answer] Dunes and Barchanes. They consist of loose material, sand, with slopes 20-30 degrees which easily slide. Also they can be 1200 meters high and hundreds kilometers long. [Answer] As EDL points out in his [answer](https://worldbuilding.stackexchange.com/a/185700/79455), a mountain of loose rock will not be very steep. I remember from avalanche course that the mixture of various sized rocks (such as it can be found at the base of steep couloirs) is typically 35°-40° steep. While incredibly strenous to climb this is rather "hiking" than "rock climbing" steepness. I have an alternative that makes it very hard to climb the mountain and involves being treacherous: downward oriented, crumbly limestone. This can for example be found in the bernese highlands in Switzerland (most famous example: Eiger). It can be steep but crumbly at the same time. It is kind of OK to climb (although it feels uncomfortable) if friction is good but it gets prettyhard if it is wet or even icy. Being crumbly means that not all holds are reliable and on the ledges you can often find loose gravel which can cause you to slip. [Answer] I live in the state of Colorado (home of the Rocky Mountain Range). What you often have are mountains with lots of loose rocks which makes mountains hard to scale. This means that the rocks will tumble and fall as you step on them. Is the entire mountain consisting of this loose rock? No. Where is gets really dangerous is where you have a knife-edge ridge with a section of loose rock on either side with steep drop-offs thereafter. Search for "knife-edge traverse" on YouTube. [Answer] In parts of Sweden, it is common for rivers to have steep banks of sand called *nipor* (plural of *nipa*). Quoting [wikipedia](https://sv.wikipedia.org/wiki/Nipa) (and applying Google translate for your convenience, though I'm not sure it gets all the terminology right): > > The nips have been formed by the rivers in connection with the land uplift having cut into their previously deposited sediments. The nips can be up to **about 50 meters high** and can be **very steep and almost vertical**, especially in the upper parts where the silt content is often high. One reason for this is that negative pore pressures cause cementation in the silt. > > > ![Svalnipan](https://upload.wikimedia.org/wikipedia/commons/a/a1/Svalnipan1.JPG) These geological features are not stable; every other year or so there is a section some tens to a couple of hundred meters long that collapses somewhere along the river, but that just moves the slope slightly inland, and there is a lot of river banks around. Being covered in vegetation helps; grass is optimal, trees have the problem that when they they fall over they take a part of the slope with them. If you want to scale this up, I suspect the first thing to do would be to have a deeper bed of sediment for the river to dig down into. The [river Nile](https://en.wikipedia.org/wiki/Nile#Eonile) at one point when the Mediterranean was dry had apparently dug itself down **over two kilometers** at present-day Cairo. [Answer] **Bouyancy : Soil medium suspended in a non-dissolving liquid of similar density** Several answers have talked about the angle of repose and slope stability analysis. But those are all calculated in Earthlike conditions, where the atmosphere is much less dense than the sand. Consider buoyancy. Let's take a planet with a tremendous atmosphere. 500 standard atmospheres in pure nitrogen, where the density is almost 0.5 gram per cubic centimeter. Common nonreactive quartz sand is about 1.2 grams per cubic centimeter, with space between grains where atmosphere flows. We can mound up this sand very high and it will stay in place for a relatively long time compared to Earth. If left alone, the sand mound experiences relatively little pull downward. However, sideways forces will easily disrupt the mound of sand. Human footsteps will spray sand in all directions, which will fall slowly and spread out far. This mountain will not last long with people climbing it. Incidentally, the person doing the climbing must be immune to the crushing effects of this atmosphere. Any wind or currents at all will quickly carry away this mound of sand, forming a flat plain of sand. This is just like the abyssal plain in the Earth's oceans, which are vast flat stretches of organic material slightly denser than the water. ]
[Question] [ My setting takes place in the late 2100's, so the technology should inherently be much more advanced than the technology we currently possess. However, I still want to feature firearms that are identifiable in the modern day, like the AKM, M16, LSAT, AA-12 etc. The issue I see with this, is that these guns would be far outdated by almost 200 years from now. Using modern firearms a century and a half from now would be like the equivalent of using muskets or flintlock pistols in modern warfare. One foreseeable reasoning I could understand is that real-life weapons like the M2 Browning are still in use, despite almost being a century old design. [Answer] ***As long as they do a job and people like them:*** The basic job of a gun is to shoot something. A gun needs to be relatively simple and reliable, able to be ignored a lot and ready at a moment's notice. While a lot of fancy guns used exclusively for war will be outmoded as soon as a better gun is made, for self-defense people still use revolvers and automatics only slightly different than those used a century before. The real cutting edge stuff will go out, but a basic weapons is a classic. Bolt action rifles work perfectly to hunt, and I suspect the AK47 will be a militia backup in isolated places for centuries. The mechanics of firearms are only shifting slightly, except for the fancy stuff. People still make the Brown Bess because they love them, and still hunt with them because they work and it's fun. As well, new ammunition types are likely to extend the life of modern firearms. I'm not saying people will use the identical shotgun (although they might), but the basic tool is a good fit for tasks and will last until people don't need and want them anymore. [Answer] **Just how "identifiable" should they be?** I think it is improbable that the military or ordinary civilian shooters would use weapons that are **actually 200 years old**. Some collectors, maybe, but those who actually shoot their genuine antiques would be a small subgroup within a small niche. But just how different can a modern weapon be and still qualify for your "identifiable" criteria? Others mentioned the Browning M2 heavy machine gun. Let me add the [M1911 pistol](https://en.wikipedia.org/wiki/M1911_pistol) which has been around for 110 years, but the [latest variant](https://en.wikipedia.org/wiki/MEU(SOC)_pistol) looks slightly different and it also has some internal differences. Or take the M16 assault rifle. 50 years old and the family is still going strong. Here is an [image](https://commons.wikimedia.org/wiki/File:M16a1m16a2m4m16a45wi.jpg) of four different models, decades apart. Now imagine mounting a [M203 grenade launcher](https://commons.wikimedia.org/wiki/File:M4_Carbine_with_M203_Grenade_Launcher_(7414626424).jpg) under the barrel, or a [foregrip](https://commons.wikimedia.org/wiki/File:M4A1_ACOG.jpg). The [HK416](https://en.wikipedia.org/wiki/Heckler_%26_Koch_HK416) has even more differences. There is even a [9mm variant](https://en.wikipedia.org/wiki/Colt_9mm_SMG). **Why do that?** Training and logistics. Say you have a military which has assault rifles in [5.56mm](https://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO) and sniper rifles and general-purpose MGs in [7.62mm](https://en.wikipedia.org/wiki/7.62%C3%9751mm_NATO). There are factories set up to produce 5.56mm rounds. There are billions of them in your war reserve. There is an agreement with your allies about the [shape of magazines](https://en.wikipedia.org/wiki/STANAG_magazine). And then some clever guy comes along and says "replace both by [6.8mm](https://en.wikipedia.org/wiki/6.8mm_Remington_SPC)" ... Yeah. Sure. But even if you decided to make the changeover, you have scores of active duty troops and reservists trained in the old weapon. So there is a powerful incentive to have the overall look-and-feel similar. [Answer] # Give it an in-story reason What has happened in the past 100+ years? There are several reasons that firearms development might focus on the early 21st century firearms. **No need** Maybe the society doesn't need anything more advanced. If the biggest threats are lightly armored opponents, there's no need to throw more resources at firearms development. **Gun control** In 1986, the United States [effectively banned](https://en.wikipedia.org/wiki/Firearm_Owners_Protection_Act#Ban_on_new_automatic_firearms) civilian ownership of new automatic weapons. As a result, if you want to buy an automatic weapon today, you can only find pre-ban firearms ([here's an example](https://otbfirearms.com/nfa/transferable-machine-guns/)). Maybe there was some form of gun control that banned newer firearms. A country that's sufficiently opposed to firearms development might even restrict their military. Maybe there are even treaties where countries agree that they won't advance their firearms R&D beyond a certain point. **Nostalgia** I know a few people who shoot muzzle loaders or compound bows even though they're vastly inferior to cutting edge firearms. I shoot revolvers for fun. These firearms work, so why use anything else? [Answer] You kinda answered your own question with the M2 reference. If a design is solid enough there has to be a good reason to switch away from it. Unless some insane breakthrough in energy storage density occurs, it'll still be cheap and effective enough to use gunpowder powered weapons. The same basic weapon layout will still be functional enough, although I am sure there'll be some subtle differences. It is not uncommon at all to have modern ballistic operating firearms appear in sci-fi settings, sometimes even further into the future than 2200. [Answer] Beretta has been manufacturing firearms since 1526. A firearm used in the 16th Century would still fire a lethal projectile, if kept in [operating condition](https://www.gunvault.com/blog/tips-for-long-term-gun-storage/). All of the supplies needed to operate such weaponry is readily available, even to the general public ([gunpowder](https://www.walmart.com/), [pellets](https://www.walmart.com/), [paper/cloth](https://www.walmart.com/), [fuses](https://www.walmart.com/)). Technological advancements have made firearms faster, easier, and safer to operate since the 1500s, and the pace of technology won't slow down in the war department (short of some massive global disarmament policies, even then there will be a black market). Using a 200 year old firearm against a modern weapon would be like bringing a knife to a gun fight. Think about European settlers in North America coming into contact with Native Americans. It really wasn't a fair fight as far as firearm technology was concerned. And there may be an energy source yet to be discovered which would make gunpowder based weaponry as obsolete as bows and arrows. [Answer] **Fear of Gun Control** We currently have the technology for electronic controlled firing systems for firearms but gun companies refuse to research and design them. Any company that even thinks about it is targeted by group like the NRA and receive public backlash. Company shares plummet, sales plummet and shareholders riot. As a result, why change the design of a perfectly functional mechanical firearm? Any tech is new materials, new ammo and new manufacturing processes but other than that, the same basic design remains. People want a gun they can point at something and blow it away. They don't want features like geo fencing which would stop a gun being taken into a school and used to shoot a bunch of toddlers. They don't want features like a palm readers linked to the owner so a gun can't be stolen and used in home invasions. The mere though of a "safe" gun terrifies people. As a result guns won't change very much in design for a long long time..... [Answer] > > However, I still want to feature firearms that are identifiable in the modern day, like the AKM, M16, LSAT, AA-12 etc. > > > A lot depends on your reason for wanting them to be identifiable in that way. If it's to ground your future world in today's reality, a tried-and-true way to do that is to use familiar-sounding names but invented models, perhaps even harkening back to existing models. You could talk about the Browning M720 or the Beretta ARX600 or the AK-7400. If I read "AK-7400" I'm going to think of the AK-47 and expect something like it, but more modern. Similarly "Browning" and "Beretta" and such will connect your world to reality. Otherwise, if you want to literally have them use AK-47s and such, throw in a bit of dialog or narrative about how nothing beats the reliability of a simple design with a 200-year-plus track record, particularly when executed in modern materials. [Answer] If firearms designed 200+ years before are still in use by the military of any Country (guerrilla forces are going to face different priorities) it would mean at least one of the following (but not necessarily all): A - general tech development has slowed down. This may happen for economic reasons. R&D of new weapon systems is extremely expensive. That would prove quite unpopular if basic health care cannot be kept because of the ongoing economic conjuncture. Another combined reason may be lack of pressing need. One thing is if you fear any moment the enemy is going to land on your shores. Another if tensions with other nations are somewhat managed in a non violent way. B - they are still somewhat effective. Which means that development of personal armor has not progressed much. Maybe for reason A. Maybe effective armor is just too expensive to be given to the average grunt. C - They are just a part of the arsenal. While EM rifles and anti-droid weaponry is an established technology and nanotech is the cutting edge the good old firearms of the past are more than adequate to keep in check the swarms of infantry. After all grunts are much less expensive to field in 2191 D - Inertia. As pointed out in the other answers when you and your allies have large stocks of weapons and ammo it becomes difficult to justify to switch over to a complete new system. Especially if point B is valid. Furthermore: any firearm we have in use now is any good if the user is capable of detecting and aiming correctly at the target. So while a SCAR 17 will still be an awesome weapon in 200 years the big upgrade would be the aiming system, battle awareness, droids integration and so on. ]
[Question] [ Alright so in my sci-fi a prominent corporation dominated by the Borlak species (Mantis-like Hexapods). The Borlak make their money by mining "dead systems", solar systems without any habitable planets or any planets worth terraforming or colonizing. Which they, after taking the best materials for themselves, charter out to other corporations or prospectors. However the Borlak now want to tap into the stars of these dead systems. I know stars are made of mainly hydrogen and helium, but I was wondering is their any resource/element able to justify the hassle of mining stars? Note: I know they could just build a dyson sphere, but I want them to physically mine the star for something. Tech level is: fusion is common. Antimatter is a thing, but very rare and heavily sanctioned. Construction of Dyson spheres is possible but still a monumental project. [Answer] I don't think traditional mining would be possible at all. Consider that all known elements are created by stars - the bigger the star, the bigger the element they can create. These elements are not created in a solid state, this happens after the element has cooled, but in the core of a star the elements are what can best be described as a gas or liquid. And this would be the same for any element you tried to use on the surface of or inside any star - the metals and alloys would melt and become unusable as mining implements. So mining a star would be impossible. --- What would you mine a star for? Well considering the technology level of your Borlaks, they would probably find rarer elements to be more expensive and valuable. Hydrogen and Helium are plentiful in space. Any space faring race capable of dabbling with anti-matter and scouring entire planets for resources would be able to collect these elements in vast quantities with ease. But Hydrogen and Helium are the smallest elements. The larger the element, the rarer it becomes - Uranium for instance, one of the largest elements, can only be created in the very largest of Red Giants, making it one of the rarer elements in the universe - so there may be some financial gain in harvesting larger elements from Red Giant Stars, instead of having to wait the (potentially) millions of years before these gigantic stars go supernova. --- So now that we have established not only that mining wouldn't work, but there would be good reason to "mine" elements from stars, what are the options of the Borlak race? I would suggest siphoning the star. Literally sucking part of the star away into space, so the elements from the star are colder and can be harvested in a cooler environment. By sucking up the contents of a star the Borlaks could get at the bits they needed without having to operate within the extreme temperatures of a star. The only problem is the immense gravity of a Red Giant. The gravitational pull of a star that big would be far greater than any "space-vacuum" the Borlak's could develop. However, there are things out there with a greater gravitational pull than Red Giants... [![Black Hole sucking up a Red Giant Star](https://i.stack.imgur.com/cxNRw.jpg)](https://i.stack.imgur.com/cxNRw.jpg) If the Red Giant star is close to a Black Hole, the Black Hole will do the siphoning for you. All the Borlaks have to do is ensure that they don't fall into the event horizon and they should be able to collect parts of the Red Giant Star as it is ripped away and plunges into the Black Hole. --- Of course, this wouldn't be easy. The Red Giant star would have to be very close to a Black Hole for this to happen, making life very difficult for the Borlaks - falling into the event horizon would be a huge risk, and once they do there would be no escape. Also, this wouldn't be plausible for just any star - only Red Giants would make the elements you wanted. And this wouldn't be plausible for any Red Giant star either - you would need to find one that is right next to a Black Hole. But with the right conditions, and with enough care and sufficient technology to pull it off, it may be possible to harvest what you want from a star in this fashion. --- Of course, if the Borlaks were even more advanced than this, they could be carrying around their own portable Black hole with them to help them siphon off Red Giants - however if they were advanced enough to do this, they would probably be advanced enough to create the elements they wanted manually, without having to mine them at all. [Answer] No, there's no such element that would justify this sort of attempt. We have data on [the composition of the Sun's photosphere](http://solar-center.stanford.edu/vitalstats.html), one of its outermost layers. By mass, the solar photosphere is 98.3% hydrogen and helium. Oxygen and carbon compose another 1%, followed by even smaller quantities of iron, neon, nitrogen, silicon, magnesium, and sulfur - all elements found in Sun-like stars in these amounts. None of them are particularly precious or hard to find on Earth; they're certainly not worth the hassle of trying to scoop away part of a star's atmosphere. ## Chemically peculiar stars I can imagine that a [chemically peculiar star](https://en.wikipedia.org/wiki/Chemically_peculiar_star) might attract some attention. In these stars, diffusion, magnetic fields and other processes dredge up heavier elements from deeper in the star and bring them to the surface. [Different subclasses of peculiar stars](http://www.astro.uvic.ca/%7Ezhd/teaching/cp_slides.pdf) are characterized by the presence of different elements in their photospheres: * [**Ap-Bp stars**](https://en.wikipedia.org/wiki/Ap_and_Bp_stars): Strontium, chromium, europium, and silicon * [**Mercury-manganese stars**](https://en.wikipedia.org/wiki/Mercury-manganese_star): Mercury and manganese, with traces of platinum and other heavy elements * [**Am-Fm stars**](https://en.wikipedia.org/wiki/Am_star): Heavy metals Though still composed of hydrogen and helium in similar fractions to the Sun, these heavy elements are substantially overabundant compared to the solar photosphere, and provide potentially interesting targets for exploration. [Answer] The process of mining stars in science fiction is often referred to as [Star Lifting](https://en.wikipedia.org/wiki/Star_lifting) The biggest concern here is that most stars don't make anything higher on the periodic table than iron. In other words, all you will be finding in most cases is a bunch of really common elements. The good news is that you will be finding A LOT of really common elements. Apart from the hydrogen and helium which make up ~98% of our own star's mass, it also contains about ~2.984\*10^28 kg of carbon, nitrogen and oxygen, and ~9.945\*10^27 kg of other stuff like iron, nickel, silicon, etc. That is enough mass to make several Niven style ring worlds, or a single close orbit dyson sphere. This gives you two routes you can go with: **OPTION A:** Build a dyson structure, using all of that carbon, iron, silicon, etc that is already in the star. Then the star will provide all the energy you will need for the next step. **OPTION B:** Build a smaller orbital facility, and rely on scooping up hydrogen/helium from the star to use as a fusion reactor fuel source in the next step. Whichever route you go with, this leads to the same goal of making a star matter refinery. You civilization could then harness the power of the star or gathered nuclear fuels and use it to process whatever elements they need via negative net energy fusion processes, higgs field splitting lasers, and particle colliders. In short, an advanced civilization does not need to mine materials so much as they need to mine the power they need to make their materials. Once your star factory is in place, it can begin shipping anything it wants: Uranium, Gold, Lithium, Antimatter, etc: all made from the basic elements you scoop up. [Answer] There is one reason you'd want to starlift just about any solar-mass or larger star, but it is an absurdly long-term investment. That being that you can prolong the life expectancy of a star by removing mass, especially the heavier elements. For example, if we want the sun to stick around without boiling the Earth in a billion years, we could, in theory, remove as much matter, especially metal, as possible, both lengthening its age and cooling it. So it isn't the chemical element that you're mining for profit; it's time. This is profitable only if you're thinking on time scales in the trillions of years or longer, and saving up all that otherwise wasted energy for after the natural solar-mass-and-larger stars burn out. [Answer] If the hypothesis that the extremely weird elemental abundances of [Przybylski's Star](https://en.wikipedia.org/wiki/Przybylski's_Star) are due to the presence of long-lived superheavy elements in the [island of stability](https://en.wikipedia.org/wiki/Island_of_stability) is correct, maybe that would be cause to mine it. I'd be surprised if dredging a star hotter than the Sun would be the easiest way to obtain such elements though. Even among the [rapidly-oscillating Ap stars](https://en.wikipedia.org/wiki/Rapidly_oscillating_Ap_star) (of which Przybylski's Star is the prototype) this is quite a strange object, so your civilisation might not have many stars to work with. [Answer] Remember that all elements heavier than hydrogen came from fusion happening in star cores. Stars 1.3 more massive than the sun may produce [carbon, nitrogen and oxygen](https://en.wikipedia.org/wiki/CNO_cycle); I don't know about other elements but I recall most of them come from novae. So if your fictional race is mining for elements, in space, their better bet is to skip stars and go for fresh nebula around remnants of novae. That's far from efficient though. Nebula are immorally thin. Where and when they condense into rocky planets, that's when you have ores in a concentration that is maybe worth mining. [Answer] It would not be possible to mine a star the gravitational pull is too great and the temperature is too high for anything that we know of or might have available in the foreseeable future. Perhaps some exotic technology that we are unaware of might do the trick but then the question depends on what assumptions you make about this exotic technology. Even if such technology were available it would be much easier to obtain the materials from else where in the solar system. [Answer] Financial/company/profit are concepts in our current world which is based on the culture history and the current technology. In your world these concepts may not be important any more, suppose maybe someday most human being agree that always wanting more/"more is better" is the root problem---the dyson ball is an extreme example of this route. Technology always make impossible possible, and make expansive cheap, and it will always find a best way based on the current environment. Heavy elements may make some product like some molecule more easy to design since the design space is larger, but we can design molecule with the same function witout the heavy elements in the future. For example we can design a protein that functions like Hemoglobin but doesn't contains even Fe which is not even heavy. Hemoglobin is designed by nature by chance to choice Fe, but we can design it with the purpose to remove Fe dependance someday. So maybe mining in other planets will never be cost effective. Stop to want more is the only solution. The most important in this is to stop to want human race to sustain longer and longer. We appear, we consume, we try to sustain on earth when there is less to consume, we mess up (like nuclear war/fatal virus), we are finally wiped away by solar system changes (already mess up or not). Even you travel to and mine all the planet in the Universe, it is still not enough, you will try to find Multiverse, etc. If there is no multiverse , then the job of more is finnally finished. And even more in each planet we will repeat the "We are here, we consume, we mess up(optinal), we are wiped away". But what is the whole point? Clonize and mine all planets in the Universe? Is that different substancially than only live on one planet and get wiped away? [Answer] Assuming **very** powerful antigravity you might be able to profitably mine a neutron star. Much of the heavy elements in the universe come from them but the only way it gets out is in neutron star collisions. In terms of energy this is probably more expensive than building them up with fusion, but much less processing is needed. ]
[Question] [ [Boules](https://en.wikipedia.org/wiki/Boules) is a range of relative games played with small, heavy steel balls thrown on a court, such as the French Petanque and Italian Bocce. While there is variation between games in terms of how and why you thrown, and what the size of the court is, they all rely on the distinctly Earth-bound fact that thrown balls will eventually come to a stop at fixed relative positions on the ground. Now, suppose that we want to play on a space station, in zero gravity. There is no "ground". Can we devise a boules-like game, ideally similar to Petanque (i.e., everyone plays from the same position, the court need not be specially prepared, at least two dimensions of court are exploited, points are scored by some measure of proximity to a target) playable in a space where you can't rely on gravity to keep your thrown balls in place? [Answer] Trying to recreate a game intended to be played on a flat surface in a gravity well whilst in a microgravity chamber seems not only futile, but it also passes up an opportunity to create a new game that makes better use of the features of the environment that hinder conventional bowling. My suggestion: orbit bowling. Set up the court by placing the target (call it a sun or planet or black hole; whatever takes your fancy). This object floats in space and is given a generous electrostatic charge by a small van de Graaf generator ahead of time. Collision of the target with a wall or other non-game object ends the round, and may involve a forfeit for the placer. The setup therefore requires a little skill (because perfectly stationary placement may be impractical), and players take turns setting up the court for each round. The objective of the game is to throw your bowls such that they enter into an electrostatic orbit around the target for a) a certain amount of time (the length of a round, probably quite short) and b) that has a lower periapsis than all your opponent's bowls (alternate rules might require circular orbits or at least ones of limited eccentricity, but that sounds dull). Bowls that crash onto the target and stick are non-scoring. Such a move might be considered a round-losing foul under some rules, but that seems like it would discourage risky play and make the game a little less interesting. Your bowls are made of a suitable lightweight material (perhaps expanded polystrene foam? heavy bowls would be better, of course, but you start running into safety issues involving field strengths and dielectric breakdown...) and are suitably charged before the throw by an appropriate means (rubbing them on a foam sheet sounds like a reasonable method, but maybe you could have a little van de Graaf of your own). You may charge your bowls with the polarity of your choice, but to win you'll need at least one that is attracted to the target. Like-charged bowls won't orbit the target, but may be a good means of disrupting your opponent's bowls without having to hit them directly. This game maintains the basic goals of bowling-type games, whilst giving them a new and uniquely space-oriented theme. In a suitable fictional setting, it might also help practise certain kinds of orbital mechanics... --- Relevant video: <https://www.youtube.com/watch?v=m0Ei6h3LVb0> at about 3:50 He cheats a little by moving the target slightly to stop the orbit decaying. You might perhaps be able to take a leaf out of the book of [curling](https://en.wikipedia.org/wiki/Curling) and make it a team game where one player bowls and the other player (or players) on their team have limited means to shepherd the projectile and help inject it into a more stable orbit. [Answer] # Cotton balls Something with a high drag-to-mass ratio will quickly slow down and come to an effective stop before it reaches a bulkhead. Cotton balls or similar will work. (Perhaps even marshmallows might work.) This presents a 3-dimensional version of the game, with slight "terrain" based on air currents. Speaking of that, while all unsecured objects in a microgravity environment will wind up against the nearest air vent, that's not so quick as to render such a game unplayable - you just can't walk away from the game during a round and come back later. [Answer] **Overhand throw.** Petanque generally implies a underhand toss, and the ball describes a gentle parabola as initial upwards trajectory is converted to downwards via gravity. In your space game the ball is thrown with an initial downwards trajectory, in a manner akin to a cricket pitch. As in petanque, the place where ball makes contact is the player's play. In certain circumstances banked shots off of the ceiling or walls are allowed if called in advance; no slop space petanque. In your space petanque the ball might ricochet upwards and away from this initial place of impact and be retrieved by a floating space dog; no matter - the ball has a chalky coating and leaves a chalk mark to register the hit. Other variations include sticky glue balls which stay where they hit. Or the manlier version involving spiked balls (which leave holes on the court; no concern to you if you are the spiked balls type of manly). [Answer] Underwater boule. The field is a sphere of water, few meters in diameter. The center of the sphere is made clearly visible. The players float in microgravity outside of the water sphere, and launch their balls inside the sphere. Goal of the game is to get as close as possible to either the center of the sphere or to a target ball. Water drag will take care of dissipating kinetic energy via drag, and microgravity will prevent them from sinking. [Answer] I'm going to start by considering the difference between boules and lawn bowls. In boules part of the principle is to throw the ball directly to target point usually on a surface on which they would not roll well. In bowls one rolls the ball to target point. In both cases the target is a cochonnet or jack "placed" initially by one of the players. For these purposes there's minimal distinction between the two. Since coming to a halt is not a thing in space, we need to consider the dynamic equivalent, which is a stable orbit. **The indoor version** Played inside a cylinder section of a space station or other similar with a surface that's free from obstacles. The jack is placed by throwing it hard enough that it enters a steady orbit within the cylinder. The winner is the person who's boule most closely matches the orbit of the jack. Here we find the difference between boules and bowls coming though. * Boules is played on a high friction surface and the jack will eventually come to a halt. Scoring is done in the familiar manner. * Bowls is played on a low friction surface and game is time limited by the rolling friction of the balls on said surface. Scoring is a matter of who most closely matches the orbit of the jack. **The outdoor version**\* This is played by putting the jack into orbit around a planet or other suitable body. From the sundeck of your space yacht or station, boules are thrown into an orbit that should most closely match the orbit of the jack. Scoring is done using the indoor method for bowls. --- *\*because why not? Sure there might be some casualties if the kids don't clean up after their game, but who hasn't stood on a lego brick with bare feet in the dark.* [Answer] ## No Real Change is Needed Objects inside a space station are eventually going to come to "rest" assuming your space station has an atmosphere. Drag is going to slowly rob your boules of momentum, until they hang floating at some position. So the skill aspect of the game is to determine where your boules will end up floating. Bounces - both against surfaces and other boules - will also eat up some momentum. The ability to bank shots off the "walls," "ceiling," and "floor" will make this game very interesting. Over large distances, the aiming well enough to hit other boules may be a significant challenge too. I would totally play this game. ## Considerations * You probably don't want heavy boules. Heavy objects are going to have more inertia, so they will travel further. Drag force is a cube of speed - so lighter boules will start quickly, but slow down very rapidly, whereas heavy boules will start more slowly and then just.... keep going, given the same starting energy. Also, lighter boules are less likely to damage equipment, people, etc. * Your station probably has a bunch of fans moving the air around for cooling of equipment, and to prevent undesirable gases from building up in specific locations. This is going to add an extra challenge to your game - boules that stop near vents may end up propelled into motion again as they drift into the currents. * Finally, the game will never completely come to rest. Micro-gravity and air currents will move the boules over time. Probably want to put a time limit on turns to prevent unsportsmanlike behavior. [Answer] A light adhesive ball. Preferably because the ball has a metamaterial surface rather than an adhesive glue-like substance. On earth the balls have a certain resistance with the ground that slows them down upon contact. With an adhesive surface your balls would stick to the surface of the ground as long as you dont throw them downwards too hard and then roll to a stop. By manipulating how adhesive and elastic the balls are you can change the chance they'll bounce off and how much resistance they generate on the surface before rolling to a stop. [Answer] # **Guess the length** Instead of rolling the ball and have it slow down due to resistance (where you'd need to guess the power of mew) have the ball attached to string with negligible elasticity. The target is thrown out with *a length* and players then have to guess how far by measuring out the string and throwing in the right direction. Maybe there could be a holder at the start line which you use to secure the length of string you'll use and then just push off. In addition, the target could be attached to the same holder and if it is hit it can still move, but resistance is provided by this holder. --- # **Create resistance elsewhere** The idea that the resistance being supplied by the holder for the target gave me a second solution: That you just use this method for all balls.... --- Both games can be played 3D or 2D (if you specify the plane that the balls are shot off at. ]
[Question] [ Biologically speaking, what would be the best real world explanation for a pyro, torch, fire-starter type mutation. Leeching heat energy from the environment might freeze dry your surroundings. Generating energy from internal reactor not only may cook your insides but could be more difficult to push externally. Story would be in the context of science fiction so no high magic explanations, but the characteristics of the planet could work in conjunction with the mutation of the character. Ex: charged particles native to the planet that an individual is sensitive to or able to manipulate. [Answer] The simplest way for an organism to start a fire is with a [pyrophoric](https://en.wikipedia.org/wiki/Pyrophoricity) chemical. This is a chemical that will ignite spontaneously when exposed to the oxygen in air. All your fire-starter would need to do is produce the chemical in a special anaerobic organ that would keep it away from oxygen. Then the organism could spray the pyrophoric liquid as a flamethrower. Life is very good at chemistry so there is a practically endless number of possible pyrophoric chemicals that could be used for this purpose. Two that come to mind would be [triethylborane](https://en.wikipedia.org/wiki/Triethylborane) or [diethylzinc](https://en.wikipedia.org/wiki/Diethylzinc). These are simple organometallic compounds that will be easy for an organism to produce, never fail to ignite, and will burn very hot. They have been used to spontaneously ignite rocket fuel. [Answer] [Bioelectric](https://en.wikipedia.org/wiki/Electric_organ_(biology)) charge is probably the best route for ignition. Basically your firestarter produces electrical charge internally and the plasma from the discharge heats and ignites material in its environment. This method relies on the availability of inflammable material, methane or hydrogen gas from metabolic processes are probably the best route for ready flame. So a person who's had gas ducts and storage bladders and an electric organ either genetically added to their make-up or surgically implanted could make a realistic firestarter for a Sci-fi setting. [Answer] In order to start a fire remotely, one would need to emit some form of EM radiation, in sufficient concentrations, to make the target hot enough to spontaneously combust. The radiation needs to be concentrated both spatially, and temporally. Spatially, meaning a beam (mono-directionally), rather than a lightbulb (omnidirectionally), so that only the target is heated, not everything. Temporally, so that the object can be heated faster than it can cool down towards "room temperature", otherwise it will never reach the spontaneous combustion temperature. All warm blooded creatures generate infrared EM-radiation, but none we know of can fullfil the spatial and temporal constraints needed to start a fire. They also dont have the ability to turn this radiation on and off at will. However, there are also bioluminescent creatures that are able to use particular chemical reactions to generate EM-radiation in the visible light spectrum. These reactions can be activated and deactivated at will. However none of these creatures, that we know of, have the ability to concentrate the output. Lucky, there is a very effective, biological, way to concentrate EM radiation spatially: the eye. So: I would recommend some kind of reverse-eye, where the "retina" would be a bioluminescent patch, and the eye lens would concentrate the EMITTED light, onto a particular focal point. Obviously, this patch would need to generate FAR more EM radiation than familiar earth creatures do, to start a fire, which would imply the need to store a large supply of the chemicals needed to generate the biolumiecent reaction, and pumping them through the "retina" on demand. Tweaking these chemicals might allow infrared EM radiation to be generated, rather than visible-light to be generated instead. (advantageous because this form of radiation tends to be more readily absorbed and converted into heat, than visible light) By making the chemical reaction occur in a small area, the "eye" can be surrounded by insulation: e.g. like a spongy bone, or a circulating coolant fluid sac. The chemicals used to create the reaction would, since they store a lot of potential energy, be very expensive metabolically. This could be useful if you want to build in some limitations. [Answer] Channeling energy from another dimension or from the heart of a nearby star using the psychic ability known as teleportation. Perhaps the firestarter's talent is limited such that she can only teleport things in from a single location and that location happens to be incendiary hot. *Teleportation is really just a science-fiction friendly version of high magic, so I'll offer an alternative...* Perhaps the firestarter is host to an obedient swarm of nano-disassemblers whose primary function appear fire-like at a macro scale. These nanites are under her control via a cybernetic implant. *No wait, cybernetics aren't biologic. Gimme a minute...* She's a cute little blond and the lead programmer, who created the matrix where she lives, was a Stephen King fan... *Missed on "biological" again!* Long range aim-able flatulence! *Ash already offered that one!* **I give up!** [Answer] Dragons in [The Flight of Dragons](https://en.wikipedia.org/wiki/The_Flight_of_Dragons) eat materials high in calcium such as limestone. By swallowing limestone and gemstones together, the limestone can be grinded into calcium to make hydrogen when contact is made with acid in their stomach chambers. This hydrogen expands and is what enables dragons to fly, sort of like a living balloon or airship. To return to the ground, dragons release the hydrogen. They have an organ in their mouths (Thor's thimble) that creates an electric spark. This spark ignites the hydrogen upon leaving the body, thus creating fiery breath. Your firestarters need not produce as much hydrogen as is need to float in the air, of course, maybe just enough for the purposes of your story. [Answer] I always like to answer questions by asking "what similar real-world behaviors do we have that fit the bill?" I can think of a few. 1) The Bombardier beetle. This is a series of internal explosions, causing a pulsed jet of boiling spray to be fired as a defense mechanism. Now, the pulsed jet is not fire. It is merely boiling, so is at a temperature of about 100C (boiling water). Even so, this is sufficient to deter most predators, and there is video of frogs regurgitating the beetles rather than suffer their attacks internally, so the defense will work even inside a predator. And they're a good example of an animal which uses chemical reactions, showing that fire-starting chemical reaction is not out of the question. Would fire be better? You betcha! But... fire also kills. You'd need to be an animal that, if the fire gets out of hand, will not be harmed by it. Flying might help. And beetles can fly. Yay! Which brings us to the far better example: 2) Australian Black kites have been observed to [start fires](https://cosmosmagazine.com/biology/australian-raptors-start-fires-to-flush-out-prey), which flushes out a buffet of prey, kills it, cooks it, kills dangerous predators, destroys undergrowth that predators and pray might be concealed by, and generally makes life really nice for these predators. Fire might be a somewhat overpowered defense mechanism, but as a hunting behavior, it *kicks ass*. Note that the whole ecology will have to be based around regular burns within the area that a burning creature inhabits. 3) Humans. Humans make fire, and use it for basically the same reasons as the predators, as well as for heat, light, tool use, tool creation, play, sexual display, and more. Humans initially probably got their fire from the same places the birds above did, and learned to preserve it and keep it burning. Later humans learned to make it by friction, which is another valid mechanism that animals could use. Other humans learned to make it with sparks from metallic rocks, and tinder. Again, this is a mechanism that animals could use. 4) Dragons OK, dragons aren't quite real-world, but consider these dragon-like behaviors we *do* have: * Cows make a lot of methane, a flammable gas. * Birds keep stones in their crops to grind food. * Some fish-eating birds can regurgitate oily black vomit as a defense mechanism. * Cobras and tigers can spray liquids considerable distances. And by now, I'm sure you are thinking "flint stones for ignition, pressurized methane propulsion, and fish oil or other fats for sticky napalm spray". Add in the flight that we've already established is kinda necessary to take good advantage of fire without getting killed, and that's a dragon. ]
[Question] [ This question is similar to ["How would the human eye need to change in order to see in low light without any changes to physical appearance?"](https://worldbuilding.stackexchange.com/q/94437/17332), including the apsect of change to the *human* eye, only the more challenging [common fantasy ability](http://the-codex-of-monsters.wikia.com/wiki/Darkvision) most well known in [Dungeon & Dragon's darkvision](https://rpg.stackexchange.com/a/31763): the ability to see in pitch dark in shades of gray (or more realistically, [very near pitch dark](https://www.physicsclassroom.com/class/refln/Lesson-1/The-Role-of-Light-to-Sight)?). Now in the D&D version, such sight [is equivalent to seeing in pitch black as if in dim light](https://rpg.stackexchange.com/questions/78122/which-is-the-correct-rules-text-for-darkvision). While an answer that accommodates that level of clarity is fine, I'm willing to accept some level of sight where it is not that clear, simply more like shadow against slightly darker shadow in a short range. I know more [pupil](https://worldbuilding.stackexchange.com/q/90129/17332) [dilation](https://worldbuilding.stackexchange.com/a/57688/17332), as well as [additional changes to the eye](https://worldbuilding.stackexchange.com/a/94497/17332) (mainly retinal change, tapetum lucidum [though this would [cause issues for looking like a normal eye in some situations]](https://worldbuilding.stackexchange.com/questions/94437/how-would-the-human-eye-need-to-change-in-order-to-see-in-low-light-without-any/94497#comment280357_94497)) can all help in *low-light*, but is there anything *more* or *different* that can be realistically added to the eye's capability that would give true (nearly) dark vision, that still has the eye visibly look like a normal human (or elf, dwarf, etc.)? And is there actually enough "light" in an (apparently) pitch black cave to make this feasible? NOTE: I'm *not* interested in infravision (seeing in the infrared spectrum), nor in a magic solution. [Answer] Tl/Dr: There are thermal limits if you get *too* much better than what we can see. They make it impossible to see better, even with the fanciest of equipment. You may underestimate just how unbelievably pitch dark a cave is. Fortunately, we can do math. One of the first things a spelunker is taught to do in a cave is to turn out their light. You do this to learn just how dark a cave is. You do this to learn to appreciate why you *need* extra light sources. They're not optional. Consider this structure in a cave. You have an opening 2 feet by 2 feet wide. Large enough to squeeze through. If you're a real spelunker, you won't even put the word "squeeze" there... its a huge opening! It leads into a room that is 10 feet wide, and there's another 2 foot by 2 foot opening on the other side. You'll find that roughly three thousandths of the light from your opening will reach the opening on the other side. Combine that with the reality that rocks absorb a lot of the light that hits them, and perhaps a thousandth of the light goes into the room beyond. Outside, a nice sunlit space emits around 1000 cd/m^2. So one room in, you're lit by 1cd/m^2. It's roughly lit like a late sunset or sunrise. Now go two rooms in. Now there's 1mcd/m^2. This is roughly moonlight in intensity. Go three rooms in. Now there's 1ucd/m^2. At this point, we're at the [absolute limits of human vision](https://en.wikipedia.org/wiki/Orders_of_magnitude_(luminance)). Now go four. 1ncd/m^2. Cats are going to have trouble seeing here. If I may skip ahead a few rooms, at 7 rooms we run into a *fascinating* problem. Everything emits [blackbody radiation](https://en.wikipedia.org/wiki/Black-body_radiation) do to thermal excitement. 7 rooms in, it turns out that the blackbody radiation from everything is comparable to the intensity of light that's made it through those 7 passages. What does this mean? Not only is everything glowing evenly, but *your own eyevalls are emitting this radiation too*. You literally wont be able to see through your own lens because the lens will be glowing almost as bright as the scene itself. So this says we have a very small region to work with. Rooms 5 and 6 are bright enough to avoid this blackbody issue, but too dark for a human eye to see. There's a mere order of 6 in brightness between those. That's the target for your darker sight. Cats can see roughly 6x better than us. If I can handwave that up to 1 order of magnitude, that leaves 5 orders of magnitude of darksight which goes beyond what cats can see but stays above thermal limits. You could probably get another order of magnitude via better processing. In such dark environments, you'd be moving slow. If you could get your eyes to slow down as well (avoiding saccades), you could probably increase your integration time (a.k.a. eyes on target time). That could probably give you another order of magnitude. You could get another order of magnitude by dropping the resolution of your senses. When in dark environments like that, you really don't need good vision. Indeed, cats are known to have 20/100 vision or worse. Accepting even worse vision would permit you to capture more "photons per pixel," (though the human eye doesn't operate in pixels). So that leaves you with 3 order of magnitude. 1,000 times darker than what you could see with cat eyes and long integration times is that thermal limit. At that point, we're starting to turn to magic. Its rare for an organic body to push to within 3 orders of magnitude of such a fundamental limit. More likely it will evolve echolocation abilities, which will be *much* more effective in those settings. Indeed those who are practiced at echolocation can walk around perfectly without seeing anything at all. I've seen videos of blind people riding bikes, relying on nothing but sound to tell them where to go. [Answer] **Let me tell you about realistic dark vision** My eyes are ultra sensitive to light. I can see clearly into shadows most people see as black. When I was younger, I could comfortably read a book by a full moon. Noon-day sun is INCREADIBLY PAINFUL. I've never owned a pair of sunglasses that were dark enough,1 but I have had folks making the glasses for me that didn't believe I could see through them. I spend most clear days squinting at the ground. Realistic darkvision stinks. But, why are my eyes ultra sensitive? There have been facts and supposition from many doctors. * Low pigmentation on the back of the eye. This causes extra reflection for the rods and cones. * Unusually sensitive rods and cones. * A brain disorder that over-estimates the input transmitted from the rods and cones. * Too much pupil dialation (not in my case, though, during full daylight my pupils are a pinhole). And then one doctor simply shrugged his shoulders and said, "I dunno, it's just the way you are..." Frankly, any or more of the suggestions I just gave you (including, "I dunno, it's just the way you are...") are perfectly valid reasons for darkvision. What really matters is the consequences. You can't have realistic darkvision without realistic pain during full daylight (at least not that I've ever heard of). P.S., for the record, how I see at night is usually in false color. My brain substitutes color for the objects it recognizes. Dirt is usally brown. Roads are blue. Fields without trees are grayish white. Trees (think "forested") are dark green. The colors aren't magic... My brain knows perfectly well what I'm looking at, and it's doing its best to help me out. --- 1 *Addendum 2022: since writing this answer I have found a pair of sunglasses dark enough that I don't feel pain in full daylight... they're a pair of welding goggles. I look a little steampunk walking through town in my Fedora (a stylish way to keep light out of my eyes) and a pair of welding goggles, but hey - if you can't live life outside the box, what are you doing here on Worldbuilding? Am I right?* [Answer] Shortest and simplest answer is to sacrifice colour vision. In the retina, there are two primary types of photo-receptors; rods and cones. Rods are very sensitive because they respond to light across our entire visual spectrum, which is why they won't help us with colour vision but will help us see at night. Cones, on the other hand are less sensitive because they respond to specific light frequencies, meaning that when the signals from these photo-receptors are processed by the brain, we can perceive colour through a mix of different proportions of signals. But, we need more light to see with these because not all the light is absorbed by every cone receptor. This is why most nocturnal animals are in fact colourblind; they have a heavy population of rod receptors in the eye, and less cones. The species from which humans evolved had this model but as we became more active during the day, cones were more heavily distributed, especially in the middle of the retina, because being able to differentiate colours gives an advantage at detecting the camouflage of predators. It's also why our ability to detect movement out of our peripheral vision is so much better than in the middle of our eye; because the edges of our vision is still mostly handled by rod receptors. This is why on a dark night you'll detect movement, turn to look at it, and won't be able to see a thing. So, to increase night vision, replace the cones with rods, make them more dense, and you'll see a lot better at night. Mind you, it could be quite blinding through the day without being able to contract the iris to make a much smaller pupil than we have through the day now, so that is another factor. This is in part why cats have the iris shapes they do; it allows them to reduce the amount of light that gets into their eyes during the day more effectively. but, in theory at least, you should still be able to get a similar result with a strong circular iris. ]
[Question] [ What metals will a culture most likely use if use of iron is prohibited but it has advanced technology? [Answer] The main problem for an iron-less advanced civilization is *machine tooling*. Modern tool steels are incredibly versatile materials, capable of being forged and machined into highly complex shapes yet made hard enough to cut through most materials and durable enough for repeated hard use, such as in jackhammer bits (if you think a sword has a hard life, it has *nothing* on what jackhammer bits go up against day-to-day). This is something almost no other metal or alloy can pull off -- even high-tech metals like titanium struggle to match tool steels in hardenability. As a result, this civilization would have to develop a tool technology akin to *cemented carbide* very early on. If they were able to refine a titanium-like metal to serve as an elastic matrix material, and had access to the relatively common mineral zircon as well as a supply of graphite, then zirconium carbide can be made by calcining the zircon then performing a carbothermic reduction on the zirconium oxide produced when the zircon (zirconium silicate) is calcined. Otherwise, aluminum carbides can be formed by mechanical alloying of aluminum with graphite, and silicon carbide is another option (it can be produced by intensely heating a mixture of coke (amorphous carbon) and aluminosilicate clay in an inert crucible, or is common naturally in the universe albeit rare in Earth's crust). Once you have carbide particles, you can then basically mix them into molten metal without too much worry about them dissolving due to their refractory nature. The resulting *cermet* material is suitable for tooling due to its aggressive, abrasive cutting nature and good wear properties. It requires an aggressive tool to machine, though, which would mean that getting started with it would be a bit...tricky. An added bonus is that once you have a suitable machine-tool material, especially for shock-withstanding tools such as cold chisels and jackhammer bits, you have a suitable *blade* material as well. [Answer] Forbidding the use of iron will be creating problem mostly in civil engineering, where steel is used for reinforcing concrete. Hardly any metal can replace iron in this case, since it is hard to find a suitable combination of tensile strength and thermal expansion coefficient. Plausible replacements in this case would be bamboo, polymer or carbon fibers. For the rest the culture would be using all the metals we are already using. [Answer] I wonder if any culture can obtain a high level of technology without iron in the first place. So this is sort of a contradiction in itself to ask this question. Anyhow, let's examine where iron is used in modern times by humans and what replacements could be used. I am assuming that all the replacement metals are available cheaply and in excess. **Magnets** This would perhaps be the hardest to find replacement. Possible substitutes would include cobalt and nickel. **Infrastructure** Titanium could be an excellent replacement for iron when it comes to tensile strength versus weight. It would be the first choice as a building material metal and building skeletons/bridges would use titanium instead of iron. Aluminum would be another alternative for a few possible circumstances. **Everyday Items** Here again, the best replacement which comes to mind would be titanium and aluminum. **And the Achilles Heel...** All complex animals require substantial amounts of iron in their blood for oxygen transport. It is understandable to build a world where iron is *prohibited* from usage, but do not go on to build a world where there is no iron at all. For such a world, you would have to redesign the blood type of all complex animals or design a different respiration mechanism for them. [Answer] Iron isn't magic; it's just cheap and easy to work. There are lots of alternatives. For instance, aluminum in the right alloys is scary strong; it's just **more voliminous** than most other substances it might replace. Instead of this lightness being seen as a virtue, it's the source of endless bigotry; for instance no-one will admit **aluminum is the best electrical conductor known** by mass, some other units, and for many of the practical things we do with conductors. And by a huge margin, e.g. twice the conductivity of copper and silver by *mass*, and twelve times better than copper *when the unit of measure is money*. Back on track, aluminum is stronger by *mass* than iron/steel; it's not the only one. Aluminum is also staggeringly plentiful; it's the 3rd most common element by mass (despite being light) in the Earth's crust (i.e. places people are likely to mine). It's everywhere, just trapped in an oxide form. The limiting factor is the electricity used in smelting. Carbon fiber is stronger still in both mass and volume, (and potentially even a better electrical conductor), so that becomes a silver-bullet solution anywhere aluminum is not suitable. Where high-temp is required beyond aluminum's ability, there is titanium, palladium and more exotic metals. And let's not forget *bronze*. Massive steam projects would be hard; cheap high-temp piping makes that possible; i.e. factories or ships which primarily run on steam. But those are "on the outs" anyway; a modern ship doesn't have boilers, it moves energy around the ship electrically, and either has slow-loping diesels that could be made of bronze, or jet turbines that are already made of exotics. Fully nonferrous ships have been built; it's done in minesweepers and the famous Soviet "Alfa" submarine, built to elude magnetic-anomaly detectors. [Answer] Iron can be prohibited most likely on religious reasons. For example, the ancient agyptians couldn't yet produce iron from ores, their only iron source was from meteorites. They've also seen, that it is much stronger as their copper and bronze tools. They've considered it as a metal of he gods, and they've used it in jewelry. There are even ancient agyptian jewelries where iron is embedded in gold! Thus, a relegious reason to forbid iron is quite possible. What they would use instead, it depends on their technological level. First, they would likely remain in the late bronze age - it would significantly slower their technological advancement, but won't stop it. Later they will use metal tools which are not really more rare, and aren't really harder to process them, as iron. I would vote mostly on similar metals as iron - maybe cobalt or nickel. Later, their high tech industry would probably use our newest things - titanium, molibden alloys, and aluminium. Note: a culture without iron surely can't produce weapons so well, as their neighbours not having this little uncommon custom. Around from the years of the early medieval ages, it would cause an uncompensible technological disadvantage in the military technology. Compare this to our fast conquest of the ancient American civilizations. For example, Cortez with 1000 men could win the main aztec army with 300000, only because they had iron swords, armors and muskets (and horses). Meanwhile, the main ["sword"](https://en.wikipedia.org/wiki/Macuahuitl) of the aztecs was from wood injected with obsidian spikes, like this. Yes, this guy on the left looks quite dangerous, but 1000 knight on the right site, full in iron, could win 300 000 from them. [![Guy with Aztec sword](https://i.stack.imgur.com/I4NBcm.jpg)](https://i.stack.imgur.com/I4NBcm.jpg)[![Knight full in iron](https://i.stack.imgur.com/LNNjEm.jpg)](https://i.stack.imgur.com/LNNjEm.jpg) [Answer] First off, why would you ever prohibit iron? It's not toxic or anything. Banning iron is like banning electricity. However, you might still be able to manage: For cutting tools, you could use aluminum or titanium. It can form a knife very nicely (just look up "aluminum knife" on google). For magnets, you could use nickel or cobalt. Despite being much rarer, we might be able to manage. For building aluminum is surprisingly strong while titanium could be used. As a matter of fact, the limiting factor for most skyscrapers is not weight but actually height (it gets too hard to pump concrete up). Reinforced concrete would be a nuisance but as discussed we could use bamboo. [Answer] It depends a bit on what you mean by that. Scenario 1: Everyone would die. We need iron to survive. Also, let's say we wouldn't - this would ruin the economy since one would have to extract iron out of everything. There is no natural solid or liquid on this planet that doesn't contain iron. There is no substitute here. Scenario 2: (If you just ban iron and not iron salts) Let's be non-pedantic and say our species has lived for 40k years. The use of iron dates back to about 4-5k years ago. Those are 35k years without iron. Really using iron to make useful stuff dates back to about 3k years ago - and only in the most developed parts of the world. Other cultures have discovered it much much later. Check out how they were doing basic things. Goodbye advanced technology anyways. Scenario 3: (Not going back to the bronze age) Revolt, civil war, outside forces taking over the country/culture/whatever. Banning iron could simply not happen in our world unless the place is called North Korea or something. This again leads to everyone dying. Please be aware that at one point, iron had to be forbidden. Substitute iron with violence. Those so far have not really been answers to your question, but please have them in mind when constructing your world. Scenario 4: (everything goes as planned) Well, what do we need iron for? For almost everything. This goes well beyond this question. You would have to think of how to substitute iron in every single application. How many are there? I don't think anyone really knows. From construction work to machinery to cars to whatever - there is no single answer here. Iron is used in a catalyst in many chemical reactions as well as statues of famous people. Please be aware that there isn't a single answer to that question. You cannot just substitute iron with x and be happy. But it is certainly possible - and often very easy to google if you want to know how to do x without iron. There isn't an answer to that question. But I have advice: Be aware of what you are planning and at least read the wikipedia entry of an element if you want to ban it in your story. This is really all just common knowledge, but you always have to go back to the basics with these questions ... ]
[Question] [ Let's assume that somehow a hoofed creature became a carnivore. Since hoofs are inferior in every way for hunting animals, it make sense that the species would need to evolve to hunt better. Thus, if a hoofed creature evolved to be carnivorous, how would the hoof adapt to this? [Answer] Well, looking up "[hoof](https://en.wikipedia.org/wiki/Hoof)" on Wikipedia, I found that it is > > the tip of a toe of an ungulate mammal > > > And apparently an extinct ungulate, [Mesonychid](https://en.wikipedia.org/wiki/Mesonychid), was carnivorous and also had > > four digits that ended in tiny hooves on all of their toes and were > increasingly well adapted to running. > > > Regarding their diet: > > Many species are suspected of being fish-eaters, and the largest > species are considered to have been scavengers. > > > They are also considered to be related to cetaceans, some of which are carnivores. So it seems like hoofed creatures can adapt fairly well to eating fish. However, the shape of the teeth is more important. I've also heard that other ungulate species, like pigs, can be fairly omnivorous even if not truly carnivorous. [Answer] Right, firstly, animals have already done that, twice. First were the mesonychids, then the entelodonts. The reason for this happening wasn't because hooves were better or worse, it is simply because the first big animals were hoofed herbivores/insectivores. The carnivores that rose from them simply kept the hooves that their relatives had. Another thing to note is that, yes, hooves aren't great for holding onto something, your jaws are. Animals like the *Mongolonyx* had a massive head and huge jaw muscles, because their predecessors had them already. They would also have likely hunted in packs (herds?) as fossils from Mongolia are often found together. They also were not by any means primitive, as was found with creodonts (sarkastodon etc.), they had relatively carnivorian sized brains. The mesonychids were actually very successful and survived all the way up to the early to mid oligocene, while creodonts went almost entirely extinct (though the Mongolian Hyeanodontids survived till the early Pliocene). *Mongolestes*, the last known mesonychid, would have been a top predator, and it's genuinely not known why they went extinct, as they dominated their niches. I have noticed that many people say stuff like *the claw is the perfect weapon*. Yes, it is good for gripping, but plenty of animals don't need it and many also don't use them to the extent that you would think (dogs, wolves, etc). [Answer] Nature has already had a go. They were called [Entelodonts](https://en.wikipedia.org/wiki/Entelodont) or [Archaeotherium](https://en.wikipedia.org/wiki/Archaeotherium) and were large pig-like creatures which became extinct about 16 million years ago. While not quite out and out carnivores, they were certainly capable of being the apex predators in their environment. [Answer] Regarding "hooves are inferior in every way", no they are not. Yes, claws are useful, its why Carnivores (as in members of Carnivora) have them. But if you've ever actually looked at a hoof, they are very useful weapons in there own right. Claws may slash, but hooves *bludgeon*, and as a result can kill much quicklier and cleanlier, especially if the hoof is uncloven. People have died from horse kicks. [Answer] I fail to see why a hoof is inferior for hunting. What it really comes down to is the hunting style and the preferred prey plus the terrain. I can see a hoofed predator hunting it's prey by speed and stamina. It just runs the prey down until it collapses with exhaustion. Any sick or weak herd members will collapse first and the pack will close in on them. Think open grassland with little cover. ]
[Question] [ In short, [Miller's Planet](http://interstellarfilm.wikia.com/wiki/Miller_%28planet%29) is described as a "potential habitable planet" with very massive tidal waves as tall as 4,000 feet. If for some reason, life began in this planet and is destined to evolve to be as smart as Humans, how would they be designing structures that should be built on raging water with usual tsunamis? What would this structures look like? (A graphic representation is a plus) Note that the lifeforms that would start here will begin without any access to advanced technologies of any aliens. [Answer] Build INTO the ground - literally. A normal building would have a problem because of this: ``` |--------| <- | | Big wave, big problem \\ | | <------------- | | The building has to withstand | | / \ all the force hitting it | | / \ | [] | / \ ---------------------------------------------------------ground------------------ ``` So the solution is simple. Don't get hit. Dig Build like this: ``` <- ------------ "Hey, where's my target?" \\ | | The waves go over the building - it doesn't matter how big the <- / \ wave is if it doesn't hit :P / \ / \ -------=-------------------------------------------------ground------------------ | | | | (Note: the "=" is the entrance hatch to our building) | | |________|---- "Gtfo wave, nothing to hit here" ``` In other words, you wouldn't see the buildings. You'd have a lot of entrance hatches on the ground though. [Answer] This is a very broad question (starting with, what would life be like), so I'll assume and Earth-like progression of life. **Pyramids** The first coral-like structures evolved to be hardy against water erosion - they had to - and adapt to rise above water-level. Your big wave now just washes over and around their pyramid-like structure. After more and more structures mitigate against the strength of the surge. Other life soon follows, and life among the coral cities. Your advanced peoples build gently sloping ramps, and soon the wave is a non-issue. The architecture looks much like the pyramids and ramps of the hardy coral. ![enter image description here](https://i.stack.imgur.com/YIflq.jpg) **Water Life** Life evolves entirely in the water and evolves to go underground rather than to breathe air, and the wave is a non-issue. Honestly, there's a lot of speculation that can happen here. [Answer] **Structures could survive in deep water, or even on the floating artificial islands on the surface of the ocean above deep water** The wave height shown in the movie is largely due to [wave shoaling](https://en.wikipedia.org/wiki/Wave_shoaling)'s amplification of wave height in shallows: ![wave shoaling amplification animation](https://i.stack.imgur.com/WwlzI.gif) Tsunamis don't swamp seagoing ships that are underway out over deep ocean. [Answer] I would say, they would likely be at least amphibious beings or more fishlike. Can live under water. As such much of their building can take place below the oceans waves where tidal waves will have much less effect. The other option would be far inland where the waters have lost most of their destructive force and are just strong currents. Under water, they can be any shape imaginable, even to the point they can sway in the ocean currents like sea weed. Which might be what the actually use to make their homes. [Answer] I don't think life would evolve to any kind of tool development on Miller's world because of the very long list of conditions described in this other [answer](https://worldbuilding.stackexchange.com/a/2496/10364). There's just no calm enough place to develop fire or tools, which are prerequisites for building any kind of human level infrastructure. Life would pick one of at least two strategies for living there. A filter feeder attached to the bedrock or a free-floater living in the standing wave. The closest earth analog to the ecology of Millers' is a [tidal pool habitat](https://en.wikipedia.org/wiki/Tide_pool). [Answer] As mentioned elsewhere in the comments, [there are multiple interpretations of the waves.](https://physics.stackexchange.com/questions/161004/surface-waves-on-dr-millers-planet/161041#161041) I'll stick with the *sloshing*, so that it is entirely possible that the waves are only present on the side of the planet that faces the black hole. In this case, the planet rocks forth and back by a small angle, and the wave is basically fixed. In this situation, the path of destruction due to the wave is rather limited, perhaps a couple of degrees, and most of the planet should be "safe". Intelligent life can safely form on the outer edge of the path of destruction. Provided that the wave is directly in line with the black hole, and the planet oscillatory tilt angle is small, there should also be an equally small (safe) area that also experiences a day and night cycle (one hour, in the case of Miller's planet). Provided that the waves are not the real threat, as long as one chooses the right place, the real issue with building structures would be to deal with the forces exerted by the black-hole. I would expect pyramidal, or small dome structures to survive better than towers or stilted buildings. Given that the planet rocks forth and back, that it is tidally locked, and that the black hole gravitational pull is typically not perpendicular to the surface of the planet, we should expect a non-negligible amount of shear forces along the z-axis (the height) of any structure. Reducing the height of the construction and increasing the section should reduce the chances of failure. Among flat structures with a large base surface, pyramids and domes have a better distribution of inner stress components and are easier to build compared to rectangular blocks. A pictorial representation, the green area should be safe from the waves: [![Miller's planet](https://i.stack.imgur.com/Dx3eB.png)](https://i.stack.imgur.com/Dx3eB.png) [Answer] Their buildings would float, simple as that: [![Candock floating dock, with surfers](https://i.stack.imgur.com/Dq2Of.gif)](https://i.stack.imgur.com/Dq2Of.gif) Vast mats of linked pontoons would rise and fall with the waves; walls and roofs would flex to conform to the expansion and contraction of the undulation of the flooring substrate, perhaps little more than canvas-like fabric drapped from ropes strung between poles. Nets would hang in strategic places to catch anything dislodged as the flooring tips, and anything of value would either be lashed to poles or tied down to the pontoons. The leading edge of such structures would probably come to a point and curve upward to help stay above the first swell of the approaching wave, much like a canoe. You might imagine a 'town' as a series of parallel outriggers linked laterally: [![Outrigger canoe](https://i.stack.imgur.com/nNd3M.jpg)](https://i.stack.imgur.com/nNd3M.jpg) [Answer] I believe that the cities should be built on the poles because the water is frozen and because Gargantua is only visible on a small part of the frozen poles, making the tides lower. [Answer] ## We'd Change What We Call Buildable Land We generally do not build on the beach, or in marshes for a similar reason to your aliens -- the technology we have at the time can't cope with the shifting sand, rush of tide. I'd suggest that, similarly, your evolving air breathing species' on a 1.2 km-tide planet would build their structures in the areas that are high enough to be safe from the waves. They'd consider the area under the surf to be unsuitable for building. **As technology progressed** you could build down, into the ground. Or you could build seawalls reclaiming shallow or sheltered areas that aren't exposed to the strongest of the tide. Or you could build floating cities as some have suggested. However, to answer the question : I think your evolving species would start with whatever dry ground is available. [![enter image description here](https://i.stack.imgur.com/2VVWA.png)](https://i.stack.imgur.com/2VVWA.png) ]
[Question] [ Think Humanity in Space, somewhere around 1000 Years from now. My main character wants to 'call' somebody in the vicinity. I would like to use a telephone, if that wouldnt be entirely ridicolous. Therefore I am asking for you opinion and ideas. What will everyday communication (devices and use) in the far future be like? I have the following criteria: * No lengthy explanation needed, easily understandable to the reader. * Possibility of Encryption and Interception. * Mainly about communication in space, atmospheric effects can be dealt with, but it's no requirement. * No FTL-communication (important for the plot). As always, thanks for the help! [Answer] Thought-activated implant. You decide to call, they decide to take the call, and presto! Talk away. Mild extrapolations from current encryption technology can provide security against eavesdropping. Heck, it can be done today between people who met in person before, if they bothered sharing a secret key. [Answer] It's 3015 and you're in space. Where do you keep your technology? Well, everywhere! Right now, every living human in space is no more than a meter or so from some pretty sophisticated tech. So why not assume that there's technology literally everywhere that your characters go, and they therefore don't need to carry anything around with them. Perhaps they have a digital personal assistant that follows them through the architecture behind the walls and is always running locally, or perhaps everyone interfaces with a single program that serves everyone. Note that I'm not assuming AI, just a more advanced form of our current, non-sentient programs, which I imagine most readers will be familiar with. So to make a call, I'd just call out into the air and my assistant would place the call for me. Of course this implies speakers and microphones placed everywhere, but by then they'd be so small and cheap that that's entirely acceptable. Similarly, there could be cameras and screens (or holo-projectors, direct-to-eye lasers, or whatever kind of display tech you like) if you want video calls. Of course all this brings up questions about privacy, but that could play into your criteria about encryption and interception. As for the technology that sends the signals across space, unless it's a plot point then if you want to avoid explanation to the readers, just don't mention how it works at all. I imagine there'd be some kind of networking systems similar to our current ones for transferring data, but there's no need to go into details if you don't want to! [Answer] [**Subvocalization**](http://en.wikipedia.org/wiki/Subvocalization) A very small detector is placed on or in the user's throat. When you "think" words and say them out loud in your head, the muscles in your throat will move as if you were saying them, but with no air it doesn't create any actual sound. The detector looks for these movements and translates them into speech/commands, without you talking out loud and bothering people around you. Small speakers in your ears (either like hearing aids or as implants) deliver sound to you. Adding in glasses would give you two-way video (they'd have super tiny cameras), plus a HUD overlay of your surroundings. Since we're a 1,000 years in the future, I suspect even those tiny devices would be capable of their own "cellular" connection (I use that term very loosely because at that point I'm sure they'd use something far different). This is, basically, a super-advanced phone. The primary benefit is that since you don't need to say anything out loud, you can talk without air. This lets you talk without bothering others, or in space. You would, of course, need other scientific advances to make that survivable, and therefore useful. [Answer] I would go for a StarTrek-style communicator. A simple wearable device, voice controlled, and maybe touch activated. It is easy to understand, easy to handle, and seems fairly failsafe. It also seems to fulfill your other requirements. If necessary, you could add a headset like nowadays bluetooth bits, maybe in-ear with a skull microphone, if you like. [Answer] Technology becomes obsolete. Replacing an implant every 2-3 years sounds painful. You would use existing infrastructure. Since we are already surrounded by sensors I imagine in the future you would ask your personal assistant in the cloud - a la siri only way smarter - to call so-and-so. Sensors in the ship or station or home register your voice and that you said you pa's name and it will make the call. [Answer] I would suggest an implant that registers inside the brain when the person *intends* to talk. Thought's aren't usually organized into coherent speech patterns, so someone essentially listening to your thoughts would send an incoherent message that is all over the place. You can speak a password ("Call Mom") and that selects the person you're trying to contact, with the message encrypted with a private key, that only the person's communication implant on the receiving end can decrypt (officially, though I'm sure there are people out there that can hack it). And speaking it out loud isn't even necessary, just as long as the person is whispering or mouthing the words, the speech patterns will be recognized within the brain and be translated into regular speech to the recipient. So someone hiding in a cupboard from bad guys will be able to have a full on conversation without making a sound. Hearing the receiving message works in the same way, you listen to it straight into your brain, rather than the ears needing to register it. As for no FTL, trying to have a conversation with someone a significant distance away will be essentially like leaving messages, and when it reaches the person they have the option of listening to it as soon as gthey receive it, or can store it on their comms device for whenever they want to listen to it ("not *now* Cortana, I'm in the middle of a gunfight!") Then for two way communication, it's similar to receiving a phone call now, with your communication implant asking if you want to receive the call in real time. [Answer] *Final outcome of the technology is in the last section of the post* Currently, the cell phone seems to be becoming the "do-everything" tool that the public uses for all its mobile personal needs when it comes to needing or storing information. (*Assumably you call someone because you want to send or receive information?*) When they first came out, they were large and could only place calls. Since then, they have gotten smaller and smaller. They had more and more functionality put into them so they became the only electronic device you need when you are on the go, as well as became a personal storage device (*Don't see people with briefcases as often, except where paper copies are required*). Then, they started getting bigger again. *Why?* * Touch interface is easy to intuitively grasp, but requires adequate screen-space. * Having a larger screen is more visually attractive as clarity and definition increases. * It doesn't make the phones any less mobile. It seems clear that having an easy-to-see visual screen is of some importance to the mobile electronic helper, as well as having a simple and easy to use interface, otherwise it would have continued to get as small as possible while being able to fit major functions. --- To expand that to your situation - you have a person in space, probably in a suit of some kind? He at least requires some way to breathe. This suit or headpiece, or whatever the largest object you have that is personally owned and has to go *everywhere* with you, is probably the do-it-all device which is also capable of providing a mic of some kind near the mouth, and speakers somewhere in the vicinity of the head. Imagine what this person will typically be doing while placing a call. If his hands or eyes cannot be distracted, he probably has to use his voice or some other way without having to look and push a button, though a button or physically interaction would probably still be available. Then consider the screen aspect - how can they view images with their device. Holograms could be projected. If they wear a helmet, it could be a screen overlay on the interior in front of the face. It could be a touch-screen built on top of their fore-arm. Depending on the technologies you want available, the solution you choose may heavily depend on a person's daily routine. If you drive to work everyday in your space jumpsuit, its likely going to be built into the jumpsuit. If you just walk down the hall, it may be an object that automatically follows you around. --- **My ultimate solution** If just about any technology is available without adverse side-affects, I would think the perfect solution is something that is able to always be with me, but not directly implanted. It could continuously scan my brain for commands and do them just by me thinking them - with sophisticated enough technology in that area it would literally know exactly what I'm thinking. It would for the most part require no charging or plugging in on my behalf. It could easily provide audio for only me to hear, and can easily provide clear visuals. The smaller it could be, while being able to provide the above, the better. I am thinking something the size of a coin, which is typically carried in a simple slot on a belt or in a pocket, and has the capability to automatically follow you by some type of floating or propulsion technology. It is linked to my brainwaves to know when I give it a command. If I want to place a call, It comes up to my ear to provide audio and I can either talk normally or provide brain-commands. When receiving a call, it will notify me in my preferred method. Could be an audible noise, a slight visual, or vibrating. It can project an image in front of my eyes, either a translucent one or a completely opaque and super-ultra-HD one. When I get in my spaceship, there is a spot for it near my head. If I put on a helmet, it goes into the helmet first, automatically by brain command. If I am a big-shot CEO or something, maybe I have many working in conjunction - simultaneously calling people with messages, driving me to work, and grabbing my coffee for when I get there, while I use another to read the morning paper. It would seem like an extension of yourself, without actually being one - meaning you could assign it simple tasks and not have to worry about the little details of getting the task done. You can easily get it replaced if it malfunctions, send it physically to other places if needed, and store highly sensitive or personal information only on it. [Answer] Vernor Vinge in *Fast Times at Ridgemont High* and [*Rainbow's End*](https://www.wikipedia.org/wiki/Rainbows_End) describes contact lenses that provide augmented reality, and computing and sensor ability in clothing that lets them issue commands in subtle, eventually subconscious, ways. In the far future, people still living as corporeal self-contained entities (those that like exploring real-universe, for example) would just talk and use body language like they would if the person they are communicating with is in the same room to get his attention. The technology would project an image or just voice, as needed. [Answer] Think what our current tech would look like to anyone living 1009 years ago. Shocking, magical, omniscient, and powerful. Future comms tech will be limited only by social mores of the time. AI will be real. There will be total convergence between phone, computer, tv, personal coach, doctor, multi-tool, personal security guard. These devices will be available as either a sentient companion, intelligent fashion accessory, tattoo, or implant. Perhaps people will be assigned a robot companion and mentor at birth. It sounds creepy but so is the internet and facebook today. Perhaps it will be handy to have a credit card sized gizmo that unfolds like paper to a screen the size of an iPad. Calls could be a tactile 3d version of Skype or voice-only depending on the choice of the users. The infrastructure might use quantum entanglement for instantaneous communication over a short distance, or some other exotic particles like tachyons or neutrinos that travel at relativistic speeds. [Answer] > > "I have the following criteria: > > > No lengthy explanation needed, easily understandable to the reader. > Possibility of Encryption and Interception. > Mainly about communication in space, atmospheric effects can be dealt with, > but it's no requirement. > No FTL-communication (important for the plot)." > > > Then you won't be building a science based universe as quantum entanglement should provide instant (ftl) and un-intercept-able communications for pretty much everyone by that time period, given they have already achieved it at short ranges now. It may be however that this requires relatively large equipment e.t.c. but at the very least, quantum entanglement would be used much like a telephone hub, the first 'hop' to the hub may not be via quantum entanglement, but the middle part of the journey will be. Must like current telephone systems use copper cable from the phone to the exchange, the signal leaves the exchange via fibre-optic cable to another exchange. In this case a purely local call would be still via radio, either a star-trek style voice activated job, or a true thought controlled device (via implant or a piece of jewellery). As for the entanglement, you could impose a range limit (say 0.5au) which would require repeater stations, if they were damaged, it couldn't be used, however its very unlikely there would be a man-sized communicator capable of throwing transmissions over distances where there would be a noticeable time-delay, even 1000 years from now. The power required for that by anything but quantum entanglement is absolutely massive. ]
[Question] [ One day, the earth suddenly gets covered by a spherical barrier that allows waves (light from the sun, radio, etc.) to pass both ways, but not matter. Let's ignore the feasibility of that kind of barrier existing and say that it's just there now. Anything with mass bounces right off as if it were an impenetrable wall. The barrier hovers at around 200km from the surface. Will there be a noticeable change to atmospheric conditions on a timescale of around 1000 years? [Answer] Absolutely nothing. From [Wikipedia](https://en.wikipedia.org/wiki/Atmospheric_escape#Earth): > > Atmospheric escape of hydrogen on Earth is due to charge exchange escape (~60–90%), Jeans escape (~10–40%), and polar wind escape (~10–15%), currently losing about 3 kg/s of hydrogen. The Earth additionally loses approximately 50 g/s of helium primarily through polar wind escape. Escape of other atmospheric constituents is much smaller. > > > Some math: * 3 kg/s would be 9.461×1010 kg in the span of 1000 years. * The atmosphere is 5.15×1018 kg. * 9.461×1010 / 5.15×1018 = 0.00000001837 The atmosphere would gain 0.000001837% mass. Completely negligible. [Answer] ## As for loss of Atmosphere... The atmosphere weighs [$\pu{5.148 \times 10^{18} kg}$](https://www.jstor.org/stable/26253433#). Earth loses [$\pu{3050 \frac{g}{s}}$](https://en.m.wikipedia.org/wiki/Atmospheric_escape) or about $\pu{96.24\times 10^{6}\frac{kg}{year}}$. Or about a fraction in the ballpark of ${2}\times10^{-11}$ of its mass is lost per year. In other words: nigh nothing compared to the mass of the atmosphere is lost. Stopping that neglectible loss will have neglectible effect. To even be noticeable as a 1% difference from the predictions, earth will need to run on about $10^9$ years. Remember that earth is only about $4.5\times10^9$ years old. ## Non atmosphere side effects 200 km is well below the common Low Earth Orbit, and thus almost no new satellites can be put up, especially nothing geostationary or with sensible retention times. The ISS is at a 413-422 km orbit, and thus will be cut off. Meteorite impacts and debris will stop at the 200 km line, changing the pleiads and others from straight shooting-stars into ones with a bend. ## If it does not ignore relativistic mass... Now, there is *one* thing that we need to ignore for the above to be true: [Relativistic mass](https://www.desy.de/user/projects/Physics/Relativity/SR/light_mass.html). As long as we ignore that light *can* behave like a particle that has a mass, everything is hunky-dory and earth is fine. The moment that the shield does *not* ignore relativistic mass, things get bonkers: the shield turns the Albedo of the planet from something like [0.3](https://earthobservatory.nasa.gov/images/84499/measuring-earths-albedo) to 1. That means not 30% of the light falling in is reflected to the stars, 100% are. That means multiple things: * Earth's sky now is dark. Welcome to a sunless, starless world where nothing grows and everything will equalize its temperature to about the average of the planet's temperature over astronomical time scales. * Because Gravity is *not* traveling but existing as a potential field, we'll *still* feel the pull of the sun and Moon and can measure the tides. * We stop being able to communicate with our satellites already out there. We couldn't send any out there anyway due to the shield, but we can't call them anymore either if it does not ignore light. Or see them, see above. * We suddenly can see beyond the curvature of the planet! Light and radio waves will be bounced from the shell back to Earth. In the right conditions, you can even *see yourself looking away from you* reflected around the planet once... provided that you stand under a streetlight. [Answer] ## Major volcanic eruptions could be noticably worse On the day-to-day of things, you'd not notice much difference, but anytime a major volcano erupts somewhere in the world, the climate impact it has would be increased. For example, the recent Tonga volcano eruption is reported to have sent about 8% of its mass ejection off into space. This % only goes up as a volcano becomes more powerful; so, the bigger the volcano, the bigger difference this shield will make. For example, the Mount Tambora eruption in 1815 was about 15-20 times as powerful as the Tonga eruption. As it was, this eruption caused the "year without a summer", but had there been a shield like this, it could have possibly doubled the intensity of the volcanic winter. In the past 1000 years, there have been 8 eruptions on Earth big enough to cause noticeable climate impacts that would have been made at least 10% worse by this shield. So, most of your next 1000 years, would be unaffected but within that time period, you'd have a few bad years where it makes a significant difference, and probably at least 1-3 where things would get really really bad for anyone unfortunate enough to be alive at the time. [Answer] There would be very little effect upon Earth itself as others have pointed out. All existing satellites would eventually cease to function and would not be able to be replaced so no more space exploration and GPS, Satellite telecommunications, Earth observation and more would be ended or very seriously disrupted. On a more positive note there would (presumably) be no danger of a civilization destroying asteroid impact. [Answer] The escape layer of the atmosphere is several thousand kilometers up, which is many times as high as the shield at about 200 km. So the atmosphere above the shield would continue to slowly escape into space, but the shield would stop gas from lower down from moving up to the upper atmosphere. Thus the atmosphere above the shield would diminish faster than it does now. However, the slow rate of atmospheric loss should mean that will not be a problem in the long range, and certainly not during the time scale of most stories. Micrometeoroids burn up lower than the shield, so people would no longer see meteor trails in the night sky. Instead space dust would hit the shield and be shattered or even vaporized by the impact, or possibly merely sit on the shield. Larger space rocks and asteroids would also be stopped by the shield, perhaps exploding spectacularly. Since dust particles are opaque, the higher the percentage of the shield's surface which was covered by dust particles, the lower the percentage of the sunlight hitting the shield that would reach the surface of the Earth. I expect that dust buildup on the shield would probably be far too slow to be an important factor in the story. > > The ionosphere (/aɪˈɒnəˌsfɪər/)[1][2] is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level,[3] a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth.[4] It also affects GPS signals that travel through this layer. > > > <https://en.wikipedia.org/wiki/Ionosphere> So about a fifth of the Ionosphere would be inside the shell and about 4 fifths would outside the shell. If being outside the shell caused major changes in the Ionosphere it could affect long distance radio on Earth. But I don't think changes in the ionosphere would happen fast enough to affect the story, unless you are planning to write a multi billion year future history like Stapledon's *Last and First Men*. So far I have not been able to think of any changes to the atmosphere that the shell at 200 kilometers would make happen fast enough for the purposes of a story. But if an expert in atmospheric physics can think of a change which would happen fast enough to be important for a story, they should mention it in their answer. ]
[Question] [ There's this old trope where an alien being has a name that "can't be pronounced by the human tongue", but no one (afaik) has ever done the work to make that scientifically possible. Now, I'm not talking about completely alien creatures lest the conjecture becomes crazy, so I'm limiting it to animals that already exist. Is there an existing configuration of animal teeth/lips/tongue that, without a special throat configuration, could theoretically pronounce a consonant sound that human teeth/lips/tongue cannot produce, but human ears can hear? [Answer] Have you ever wondered how a cat purrs? How it makes the sound, I mean. Purring comes from the throat rather than the mouth, but bear with me, I'm going somewhere with this: it turns out that the rhythm of a cat's purr is generated in the brain rather than the throat. It's sort of like they're just saying "gugugugugugu" really quickly, and they have a special neural circuit that makes it possible to do it that fast and consistently. Now imagine that your aliens' throats and mouths have completely human anatomy, but their brains are different, and in particular, they have special neural oscillators like the ones cats use to purr. Unlike a cat, these oscillators control the movement of the tongue rather than the throat. This allows them to move their tongue in a rhythmic motion much quicker than any human could. Imagine if someone could say "kakakakakakakaka" so quickly that the syllables merged together into a single purr-like tone. Such a sound couldn't be produced by any human tongue, but it's probably quite anatomically plausible. [Answer] Easy, birds. Birds have a syrinx (compared to a mammal’s larynx) which is a set of binary vocal cords that enable them to emit two different sounds at once. This is what enables songbirds to produce such long yet rapid songs. These beings could have a syrinx which makes their names unpronounceable to humans, because it requires the speaker to produce two sets of syllables *at the same time*. [Answer] For real animal noises, crocodiles and aligators make drum thump noises when their mouths snap shut. Humans can make drum thump noises but only as vowels, so we couldn't vocalize another sound over it. Rodents grind/chatter their teeth (*bruxing*); humans can do this but we are too big to do it at the same frequency, and it is injurious to us to do it for long. I suspect that scaling humans up or down is an easier way to make the sounds you're asking about than looking for animals. If whistles count as consonants and unproducible notes count as unproducible sounds, it would be easy to imagine a mouth configuration that could produce a lower or higher register than humans can duplicate, just by scaling the relevant parts up or down, exactly as scaling up a flute makes flute sounds that a smaller flute cannot duplicate. Unvoiced tongue and lip trills would likewise be easy to scale up or down, creating trill rates lower or higher than humans can duplicate. Since humans come in a variety of shapes and sizes, with plenty of humans in any extreme, there are plenty of humans that can make lip/tongue/teeth based consonant sounds that *most* other humans are physiologically incapable of making, simply because they have different mouth shapes. If you allowed real structures other than real animal lips, tongues, and teeth, but still excluding throat configurations, it's easy to imagine something like a rattlesnake tail as a mouth part, or even a person with little jingle bells as lip piercings, who could easily create jingly consonant sounds that no unmodified human could ever duplicate. If you allow for inability to produce certain sounds *without extensive training*, there are many human languages that other humans cannot duplicate. For an extreme example, see: [Taa](https://en.wikipedia.org/wiki/Taa_language), which is almost impossible for adult learners to reproduce - but less difficult examples are everywhere. Think of the Korean consonant b/p consonant *bieup*, which most English-speakers can't produce, or the English *z*, which most Korean speakers can't produce. An alien with the perfectly human name *Zachary Hill* who encountered Korean astronauts might reasonably conclude that his name was entirely "unpronounceable in your human tongue". An alien with the perfectly human name *ǃnˤù.ṵ* would find the same for almost any variety of human astronaut, unless the Taa beat the rest of us to first contact. [Answer] This is an "almost." When I was younger, I would sometimes try to do a tense bilabial fricative (as if playing a trumpet) and hum at the same time. It was **VERY** hard to do and impossible (for me) to maintain for even a half-second. But an anteater's tongue is so different from ours that I'm sure they could produce sounds we cannot. And I suspect an elephant can make sounds we can't. The only reason aliens on TV look so much like humans is that they are portrayed by humans. Some being that developed light-years from here—why should we expect them to have any resemblance to any terrestrial creature? Some human languages have sounds made "ingressive"—with air going inward. But we are quite limited in what we can do that way. With a different mouth shape (if they have mouths) and different lungs (if they have lungs), who knows? ]
[Question] [ To give context, the setting I'm working on is one where advanced genetic engineering and biotechnology are plentiful. The premise is this, the coffee industry is dominated in the tropics by a cartel that brooks no competition. So as a result one of the characters decides to go against this by taking a coffee plant and modifying it to be able to grow in temperate climes without the need of a hothouse or anything besides the local soil. What changes would a coffee plant need to grow and flourish outside the tropics and still be consumable to humans? [Answer] **Fish Flavoured Coffee** Scientists have added the antifreeze genes from a deep sea flounder to tomatoes to produce a frost tolerant variety [![enter image description here](https://i.stack.imgur.com/YkhtJ.png)](https://i.stack.imgur.com/YkhtJ.png) See [Expression of antifreeze proteins in transgenic plants](https://pubmed.ncbi.nlm.nih.gov/1932678/) They also have added to strawberries and other plants. [Answer] **Mutant** [![frost killed coffee](https://i.stack.imgur.com/MYMpI.png)](https://i.stack.imgur.com/MYMpI.png) Your protagonist receives a package with a photo and some coffee fruit. The photo is what looks to be the sole survivor of the Brazillian frost that wiped out all the coffee plants. Except this one. In his greenhouse, and then his yard, your protagonist grows the cold hardy coffee plants. If your story is about the geopolitics of coffee economics, that will be enough. If your fiction is about genetic engineering, you can have your scientific-minded protagonist realize that there are some unusual things about this unnaturally hardy coffee plant. It may have come to exist as an unrealized and unintended byproduct of other activities going on near its origin. [Answer] # Frost tolerance and a longer vegetative growth period. The plant cannot survive freezing temperatures because it lacks the natural “antifreeze” chemistry to protect its cell walls. So the plant’s genetics need to change, which will drastically and unpredictably change the flavor of the beans. The plant normally goes through a 12-15 month vegetative stage during which it has a very high Nitrogen intake, before entering its 4-5 year fruiting cycle. A poor diet in the vegetative stage renders the bean quality and size deficient for the rest of its life. So in cooler climates it will need more time to develop its vegetative maturity. This will also have unpredictable effects on bean taste, size, and quality. So we may be able to force the plant to grow in a different climate, the question about the economic value of their new product can’t be answered empirically. I refer to [research found here](https://massivesci.com/articles/coffee-climate-change-robusta-arabica-temperature-hot-cold/) in my response. [Answer] There's no need to modify coffee bushes to grow outside the tropics. Coffee has been raised successfully (from a botanical point of view; economic success was compromised, as I understand it, by industry prejudice) in the Cascade range of Washington state, an area that experiences hard freezes, long dull winters, and heavy snowfall (but is wet enough, which I understand to be the real limitation and the reason mountainous regions are preferred in Central and South America). Further, many of the current commercially successful coffee growing regions are mountainous enough to experience winter conditions from time to time, even in the tropics and subtropics. Colombia and Ecuador, for instance, have glacier-robed peaks (though coffee isn't grown quite *that* far up, it is grown high enough to experience sporadic freezing nights)., [Answer] **Do you really want to get rid of greenhouses?** Coffee plants need low lighting and cool, but not too cold temperature. That is a plant that would grow well in a skyscraper greenhouse. Now they are expensive, but prices could go down in the future. The real trouble with modified plants is that if it is really good then you have to protect it from the competition that would try and steal some samples that could be grown in countries that do not recognise your patent. If the value of your plantation is in the advanced greenhouse that would be more difficult to copy and compete. [Answer] It's probably fairly straightforward to use GM splice in a "natural antifreeze" gene to give the plant some frost-tolerance. I suspect the reason it hasn't already been done in the real world, is that "GM" is seen by many consumers as something akin to "radioactive": something to be avoided at all costs! The other way would be the plant-breeder's approach. Crosses between plant species are far more frequent (and far more frequently fertile) than in animals. So, find somewhat related species that are already frost-tolerant and cross away. The hard bit here (if you can create a frost-resistant cross at all) would be that it has to taste at least as good as an Arabica. Genetic analysis might prove that the gene for frost-resistance is already in coffee plants, but silent. In which case selective breeding with or without shaking things up would also work. "Shaking things up" means increasing the mutation rate using hard radiation or nasty mutagenic chemicals. Not very many people know that a hard radiation induced mutation is how we got pink and red grapefruits! For your plot, though, you might get a thriller by allowing the plant-breeder to strike the jackpot. A frost-resistant cross that tastes simply superb! Then some nasty people decide that illegality is the best way to deal with the new competition.... [Answer] Really the solution is to grow it under glass, as is done with tomatoes and many other fruits, to extend the growing season near where they're wanted. Citrus fruits have been grown this way in frosty countries for centuries. Given the land area and energy inputs required, the result would be an expensive luxury. But if a hothouse is ruled out, walled gardens can be kept frost-free by using the heat from decomposition in composting. Apart from avoiding frost, coffee plants don't need particularly warm climates, which is why they do better at altitude. As new species in the Coffea genus are still being discovered, it's possible that one will be found that can tolerate a little frost, either as your productive crop or a parent in cross-breeding Pollination is also necessary, but honeybees can do that. ]
[Question] [ I'm trying to chart the roadmap of the evolution of a variety of fictional amphibian creatures which hunts in pairs. But, I don't know of many inspirations in nature where animals hunt in pairs. What history/evolution/environment would incentivize through conscious thought or instinctively of selective pressure of a mid-tropic-level species to hunt in pairs? [Answer] Hunting in group gives the obvious advantage of the number, but there is no hard limit to stop it at just two, because the more the better. The only stop to the size of the hunting pack is the size of the prey: you can't feed 100 hunters with a single sparrow. Therefore the only plausible way to favor pair hunting is to have preys big enough to feed a couple, which would probably be a male and a female, and not more. Or you could have the pair be composed by two different species in a sort of mutualistic relationship, like the notorious case of the African bird which helps honey seekers in finding beehives in exchange of a share on the hunt: the bird has a better way of finding the beehive, while the human has more ease of cracking it open. [Answer] **Brothers.** [![cheetah bros](https://i.stack.imgur.com/lLsObm.jpg)](https://i.stack.imgur.com/lLsObm.jpg) [source](https://apta.biz/2020/02/12/uk-born-cheetah-brothers-arrive-safely-on-african-soil/) Cheetah brothers stick together and hunt as a pair or trio. It makes sense for brothers to cooperate. They share genetic material and so cooperation produces a fitness benefit for their shared genes. In an area with a diversity of prey sizes, teaming up with a brother allows them to take down large prey out of reach for a single animal such that cooperation does not mean less meat to go around. This also decreases food competition with the local females and cubs which are probably related to the brothers. In a species where males are uninvolved with rearing young, a noncompetitive brother unit might both mate with the same female. The resulting cubs are from one of them, or maybe both; all ok from an evolutionary perspective. [Answer] # Dichotomy: Any time you might have specialization of function, having a representative of each kind would be a distinct advantage. Imagine, if you will, a species where the male is strong and has great endurance, while the female is quick and has a preponderance of fast-twitch muscles and explosive outbursts of activity (or vice versa). The slower, stronger member can stalk (possibly even carrying the quick one), then when the prey is in range, the quick individual sprints to the prey and goes in for the kill. The strong one can protect and care for the quick one in the event of an injury, and the strong one can butcher the animal or carry it back to the den/home. But the strong one is too slow to catch the prey, while the quick one has too little endurance to stalk. * This dichotomy could also be a generational factor as well. Adults/elders are slower but have grown large and strong. Older individuals may be skilled trackers and observers, and they advise or train the younger, quicker members. So prey requiring both quick reactions AND a lifetime of experience would need pairs like this. Pairing minimizes the number of individuals needed to be fed. This could be a mated pair OR a parent and child. [Answer] **Breeding Pairs** [![enter image description here](https://i.stack.imgur.com/g5Rjt.jpg)](https://i.stack.imgur.com/g5Rjt.jpg) Many animals form pairs to raise their young. It requires no leap of imagination to have animals that stay in pairs the rest of the year. This includes hunting together. Easy. [Answer] For more about co-operative strategies like this, google 'evolutionarily stable strategies' or ESS. There are many like the cheetah brothers where evolution prefers (even slightly) co-operation that might otherwise seem lacking in benefits. And usually these strategies are not easily replaced by others. <https://en.wikipedia.org/wiki/Evolutionarily_stable_strategy> [Answer] I think you could cause a limit in the hunting group by having a predator in the environment. This may not cause a hard limit but would be like a soft limit if the predator is large and undefeatable in numbers. It needs to be large enough that it won't care about single or pairs of your creatures but if there's any more then it considers it worth it's time to hunt them down. And obviously it must be undefeatable by your creatures so that they don't just form very large hunting parties to hunt it. There's a number of ways to do this depending on how you want to and the characteristics of your creatures. [Answer] A pair of amphibians could work together to enable some relatively unique hunting tactics. One member of the pair could lie just above the waterline, feigning distress and looking like a fish out of water. When something approaches what they think is an easy meal, the second creature would ambush it from under the water. A large hunting group wouldn't be as effective because it's too hard to hide a large number of creatures in the same shallow water. Alternatively, your creatures could lure their prey into the open by mimicking their prey's call. The amphibians have relatively simple vocal tracts, and it takes two of them "singing" together to produce something that sounds reasonably like the complex mating call that they're impersonating. They're not smart enough to coordinate an entire amphibian choir, so three or more would produce a cacophony that doesn't sound like anything in particular. [Answer] ## Twin attunement A completely endogenous solution. Your species is quite intelligent, but their brain development is genetically and developmentally much more variable than ours - they have effective forms of communication, but understanding each other and accurately predicting each other’s actions is more difficult, similar to the barriers between, say, autistic and neurotypical humans. There is only one other individual who shares the exact same genetics and developmental environment as you: your identical twin. Their brain is an almost exact mirror copy of yours. You catch your twin’s meaning effortlessly, you can tell what they would do in a given situation with uncanny precision. Your mirror neurons play a strikingly accurate replica of your twin’s behaviour even when you can’t actually see them. As you can imagine, hunting together is beautifully coordinated and reliably deadly. The species births monozygotic twins almost exclusively; single births are abandoned by their mothers, and triplets are culled to two. Those who lose their twin later in life tend to die soon after, although myths abound of hardened hermits fending for themselves in desperate solitude. ]
[Question] [ What I mean is the /j/ sound (as in English "yellow" and French *hyène*) (*hyène* means hyena) is the most common semivowel around the world. This phoneme is highly conserved in Indo-European languages (this language family include Italic languages like French and Italian, Germanic languages like English and Dutch, Slavic languages like Russian and Polish, etc.). Also, the /i/ sound (as in English "hippie") (the word "hippie" is also used in French) in one of the most, if not the most common vowel around the world. Both phonemes are almost universal, as the /m/ consonant (as in English "mother", and French *mère*) (*mère* means "mother"). I know many languages that lack the /w/ semivowel like Albanian, Armenian, Greek, and Russian (the /w/ semivowel is found in both English as in "world", and French as in "oiseau") ("oiseau" means "bird"). In the universe I am creating, there is a species named ogres (their scientific name is *Homo obesus*, so they are still humans, just not *Homo sapiens*) (*Homo obesus* means "obese human"). In the most spoken language used by ogres, there are five basic vowels: 1. /a/ (as in French *arbre*) (*arbre* means "tree") 2. the sound corresponding to the a in English "fall" (and the o in French *ordinateur*) (*ordinateur* means computer); 3. /u/ (as in English "cool", and French *ouvrier*) (*ouvrier* means worker); 4. /y/ (as in French *univers*) (*univers* naturally means "universe"); 5. and the sound corresponding to French *eu* (as in French *euphémisme*) (*euphémisme* naturally means "euphemism"). There are no diphthongs in the most spoken language used by ogres, but the are long vowels, and two nasal vowels: the sound corresponding to the *an* in French *antagoniste* (*antagoniste* naturally means "antagonist"), and the sound corresponding to the *on* in French *mouton* (*mouton* means both "sheep" and "mutton"). Also, the most spoken language used by ogres has both the /w/ semivowel, and the semivowel corresponding to the u in French *fruit* (*fruit* naturally means "fruit"). So, I wonder why would a language created by mammals from the *Homo* genus lack the /j/ semivowel, and even the /i/ vowel. [Answer] TL;DR: There do indeed exist real-world human languages which do not have the semivowel /j/, the vowel /i/, or both. The very well-known Ancient Greek did not have a phoneme /j/. Māori, the Polynesian language spoken in New Zealand, is a real-world language which does not have the semivowel /j/, but does have the semivowel /w/. There is nothing to explain, because the requirements are fulfilled by real human languages spoken by real humans.   Since there may be some readers who are not fully familiar with the [International Phonetic Alphabet](https://en.wikipedia.org/wiki/International_Phonetic_Alphabet): | Symbol | Sound | | --- | --- | | /j/ | The sound of the letter *y* in the English words *yes* and *you*. | | /w/ | The sound of the letter *w* in the English words *we* and *well*. | | /i/ | The sound of the letter *y* in the English word *happy*. Very slightly different from the sound of the letter *i* in the English word *kit*, which is usually transcribed /kɪt/. (/ɪ/ is a little bit less close, or, if you want, a little bit lowered, and a little bit less front than /i/.) | | /u/ | No exact English equivalent. Like *oo* in *goose* /ɡuːs/, but short instead of long. Slightly different from *oo* in *foot* /fʊt/. (/ʊ/ is a little bit less close, or, if you want, a little bit lowered, and a little bit less back than /u/.) | | /a/ | No exact English equivalent. Like *a* in *father* /ˈfɑːðə(ɹ)/, but short instead of long. Similar to the sound of *o* in *mother* /ˈmʌðə(ɹ)/. (Note that this usage of the IPA symbol /ʌ/ is [specific to English dictionaries](https://en.wikipedia.org/wiki/Near-open_central_vowel); elsewhere, the sound would be transcribed /ɐ/ or maybe /ɜ/, whereas /ʌ/ transcribes an [open-mid back unrounded vowel](https://en.wikipedia.org/wiki/Open-mid_back_unrounded_vowel), which is clearly different.) | | /ai/ | Only very slightly different from the sound of the letter *i* in the English words *kind*, *pine* and *tile*, or the letter *y* in the English word *my*. | | /au/ | Only very slightly different from the sound of *ou* in the English words *mouth* and *sound*. | 1. "Standard" (= Attic) [Ancient Greek](https://en.wikipedia.org/wiki/Ancient_Greek_phonology) does not have /j/ and /w/. (But it does have diphthongs such as /ai/ or /au/; hoewever, those are not normally analyzed as a sequence of vowel + /j/ or /w/, and they do not behave as such.) And Attic Greek is not some obscure language... * Among modern European languages, [Swedish does not have](https://en.wikipedia.org/wiki/Swedish_phonology) /w/. (But it does have /j/.) * [Māori](https://en.wikipedia.org/wiki/M%C4%81ori_language), a Polynesian language spoken in New Zealand, does not have /j/. (But it does have /w/. For example, the word [*wahine*](https://en.wiktionary.org/wiki/wahine) "woman", which has been adopted in some varieties of English.) * And the [Tongan language](https://en.wikipedia.org/wiki/Tongan_language) does not have *any* semivowels at all. 2. Classical [Arabic does not have](https://en.wikipedia.org/wiki/Arabic_phonology) /e/ and /o/. 3. (Late) [Proto-Indo-European did not have](https://en.wikipedia.org/wiki/Proto-Indo-European_phonology) the phonemes /i/ and /u/ (and it also almost didn't have /a/). But it did have /j/ and /w/, and in some contexts those were syllabicized as [i] and [u]. The standard analysis of PIE phonology presents only four vocalic phonemes, /e/, /eː/, /o/ and /oː/. Which shows how tricky this all is. The question asks about *phonemes* (because it uses /[slashes](https://en.wikipedia.org/wiki/International_Phonetic_Alphabet#Brackets_and_transcription_delimiters)/). In PIE, there is no [phoneme](https://en.wikipedia.org/wiki/Phoneme) /i/, but there is a [phone](https://en.wikipedia.org/wiki/Phone_(phonetics)) [i] surfacing as the syllabic pronunciation of /j/. (And in the same way, [u] surfaces as the syllabic pronunciation of /w/.) 4. Broadly speaking, languages which have only a very few distinct vocalic phonemes have at least /a/, /i/ and /u/. But [Wikipedia gives examples](https://en.wikipedia.org/w/index.php?title=Vowel&oldid=1073298427) of languages ([Adyghe](https://en.wikipedia.org/wiki/Adyghe_language) and [Sepik](https://en.wikipedia.org/wiki/Sepik_languages)) with a (so-called "vertical", because of how the vowels are represented on the standard vowel triangle) three-central-vowels system of /ɨ/ (central-close), /ə/ (central-mid), /a/ (central-open); and even languages with a *two*-central-wovel system ([Arrernte](https://www.wikipedia.org/wiki/Arrernte_language%22), [Circassian](https://www.wikipedia.org/wiki/Northwest_Caucasian_languages), and [Ndu](https://en.wikipedia.org/wiki/Ndu_languages)), namely /ə/ and /a/. 5. In recent years we have all heard about [Abkhazia](https://en.wikipedia.org/wiki/Abkhazia) and [South Ossetia](https://en.wikipedia.org/wiki/South_Ossetia), over which [Georgia](https://en.wikipedia.org/wiki/Georgia_(country)) (the country, not the American province) fought and lost a [war with Russia](https://en.wikipedia.org/wiki/Russo-Georgian_War) in 2008. And guess what, the [Abkhaz language](https://en.wikipedia.org/wiki/Abkhaz_language) has only two vowels, variously given as /ɨ/ (similar to Russian ы, Turkish ı or Romanian î) and /a/; or /ə/ ([schwa](https://en.wikipedia.org/wiki/Schwa), very common, similar to the sound of the letter *a* in the English word *about*, or Romanian *ă*, or Bulgarian *ъ*, or German *e* in words such as *Auge* or *Tinte*, or the sound of French final *e muet* in Opera French and Poetry French) and /ɑ/ (similar to the sound made by the letter "a" in the English word *palm*, but short instead of long). Digression: * The *"sound corresponding to French eu"* is either /ø/ (as is *peu* /pø/), or /œ/ (as in *jeune* /ʒœn/). (The difference is that /œ/ is more open than /ø/; similar to the difference between é /e/ and è /ɛ/.) * *"[The phoneme /j/ is] highly conserved in Indo-European languages":* No. For example, PIE /j/ became either /h/ or /z/ (maybe /dz/) in Ancient Greek; as a well-known example, Latin *jugum* /ˈjugum/ (French *joug* /ʒu/, Italian *giogo* /ˈdʒoɡo/, Romanian *jug* /ʒuɡ/) corresponds to Greek ζυγός (zygos). (From Proto-Indo-European [\*yugóm](https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/yug%C3%B3m), which gave *yoke* in English and *иго* (igo) in Russian.) We have to look no further than our beloved Romance languages: /ʒ/ is the sound of the letter *s* in the English words *measure* and *pleasure*; /dʒ/ is the sound of the letter *j* in the English words *jet* and *job*. + Latin *jocus* /ˈjokus/ > French *jeu* /ʒø/, Italian *gioco* /ˈdʒɔko/, Romanian *joc* /ʒok/, Spanish *juego* /ˈxweɡo/. + Latin *jaceo* /ˈjakeoː/ (infinitive *jacêre*) > French *gis* /ʒi/ (infinitive *gésir* /ʒezir/), Italian *giaccio* /ˈdʒattʃo/ (infinitive *giacere* /dʒaˈtʃere/), Romanian *zac* /zak/ (infinitive *zăcea* /zəˈtʃe̯a/. (Spanish does preserve a sound sort-of like /j/: *yazco* /ˈʝaθko/, infinitive *yacer* /ʝaˈθeɾ/.) + Latin *juro* /ˈjuːroː/ (infinitive *jurâre* /juːˈraːre/) > French *jure* /ʒyr/ (infinitive *jurer* /ʒyre/), Italian *giuro* /ˈdʒuro/ (infinitive *giurare* /dʒuˈrare/), Romanian *jur* /ʒur/ (infinitive *jura* /ʒuˈra/), Spanish *juro* /ˈxuɾo/ (infinitive *jurar* /xuˈɾaɾ/). [Answer] ## PIE is Everywhere OP's question references "most common" phonemes - it's important to know that basically all of the most popular languages on Earth descend from the same language family (the major exceptions being Mandarin and Arabic). Proto Indo European (PIE) is the reconstructed / hypothetical root language that Germanic (English, German), Romance (French, Spanish, etc) Indo-Aryan (Hindi, Urdo, etc) and several other languages families descend from. Turns out domesticating the horse gives your culture a HUGE "first mover" advantage. (pun intended) Something like 4.5 Billion people speak PIE derived languages... which is about half the planet. So as long as you say your language is not related to PIE, you can probably get away with doing a lot of things that look "weird" to Westerners, since Western languages all have the same root. And that's before you account for any anatomical differences for your Orge people. [Answer] I think you could possibly look into the anatomical differences of the *homo sapiens* and your *homo obesus*. My understanding is that consonants are often associated with the stopping of air flow, while the vowel sounds are more associated with the shape of the tongue, mouth and lips. Going through the “ah” “ee” “ey” “oh” and “ooh”, you have pretty distinct shapes and position of the mouth, the "ah" more with the mouth open, the "ee" more with the teeth together and like a smile etc. The website <https://www.visiblebody.com/blog/something-to-talk-about-anatomy-of-speech-sounds> also points out the position of the tongue with respect to vowel sounds. I suppose speech therapists when helping children also try to help them with things like tongue position when trying to say some sounds. That perhaps is more of a justification for why there could be the ability to produce some sounds and not others. On the linguistic side as to why some languages tend to use some types of sounds that are produceable and not other sounds that are just as producible, I suspect you could blame it on dialects and how dialects shift. (Not sure if dialect is the best word to describe what I mean.) Even with English there is quite a bit of drift in vowel sounds. There is something called the "Great Vowel Shift" where between the 1400s and 1700s english speakers changed how they pronounced vowels in very significant way. Even in the last hundred years linguists have been seeing a lot of vowel shifting in the U.S. I guess another example might be related to how your *homo obesus* might hear sounds, or how their brain is wired. For example, I think Mandarin, is a tonal language, and some western people can pick up the tonal shifts, and others have great difficulty with it. One common explanation that being exposed to a tonal language when you are a baby helps build the neurological connections to better detect the changes in pitch. [Answer] # Anatomy The human mouth and associated anatomy (esophagus, larynx, diaphragm, etc.) is capable of an infinite variety of phonemic combinations. The choice to use one over the other is ultimately one of preference. One might think it comes down to using sounds that use less energy (lowest calorie use), but they would be wrong. Many cultures value overt and energetic expression. Consider the Maori Haka dance, which is actually taught in school. An outsider would think they were about to be tied to a stake and broiled for dinner, but they are actually honoring and congratulating you. Watch New Zealand win a soccer match, you’ll understand. Then there are sounds that are almost universal yet never make it into a sentence. Stick your tongue out and blow. We call that a “raspberry.” All of humanity knows what it means, but no one has ever given that sound it’s own symbol or spelling. Why? Because humans. So the true answer is anything you want. But in world, an ogre mouth is just set up wrong. That answer will sell a lot better than any philological thesis on human/ogre culture dynamics. ]
[Question] [ So this is part of a passion project of mine for an ASB alternate history scenario. Where demons from another universe invade and conquer North America. The demons have been recorded in artwork in the past but most predominately in medieval European artwork. This is due to early expeditions to Earth's past and their sightings being recorded through art. Also, the demons are technologically advanced and it's mistaken for magic. The demon civilization has colonized many planets that are similar to their homeworld in their old universe. Though demons are one species, they have drastically differing physical features. Here are examples of what I'm talking about. [![enter image description here](https://i.stack.imgur.com/Lygcx.jpg)](https://i.stack.imgur.com/Lygcx.jpg) *My Demons don't have extra faces btw.* [![enter image description here](https://i.stack.imgur.com/eqw3e.jpg)](https://i.stack.imgur.com/eqw3e.jpg) Here is the list of different physical features 1. Scales/skin or fur 2. Humanoid or animal heads 3. Beaks or snouts 4. Wings or wingless 5. Number of horns 6. skin/fur colors Now there are similarities and these include: 1. Being a chimera of avian, mammalian, and reptilian 2. All are humanoid 3. mostly the same size 4. They can still reproduce offspring, despite the differing app Though why are demons so drastically different appearance-wise? Could there be some logical explanation behind this? The demons don't seem to mind yet it boggles the mind of humans. [Answer] ## They Exhibit an Extreme form of Polymorphism Polymorphism is the tendency in a single species to come in multiple, distinct forms where a single lineage may possibly produce any one of those forms. We humans are considered dimorphic because our male and female forms are distinctly different, but some species have more, and more different forms such as ants. [![enter image description here](https://i.stack.imgur.com/NNeQ4.png)](https://i.stack.imgur.com/NNeQ4.png) ### Answering the Question with Evolution Ants evolved many different forms so that they could fulfill different roles to the benefit of the colony. However, daemons have much more complex "hives" than ants do, so their roles and subsequent forms may be far more diverse. While an ant hive uses different forms to fulfill different roles in a single spot, demon hives may be bigger... much much bigger... to demons an entire planet may represent a single hive spanning multiple biomes to which they need to specialize. So the queen produces hairy guys with big lungs to go exploit the resources in the snowy mountains, and makes scaly guys to send off to the desert, and winged guys to wrangle the local birds for live stock, so on and so forth. The reason demon forms look more or less like mammals/reptiles/birds may be because of convergence. These are forms that are very successful in an Earth like biome; so, these are the forms the demons would produce when colonizing an Earth like world. Since the demons are an inter-planetary species, they may even have forms you do not see in your setting that a queen would produce if she instead landed on Mars, Titan, or Venus. ### Answering the Question with Clarke-Tech An alternative approach, since demons are technologically advanced, is that this Polymorphism may be artificial. It is very possible that demons modify their own genetics to colonize worlds that would otherwise be too inhospitable to them. When they arrive at an alien world, they may not be able to breath the air, or endure the temperatures, of withstand the gravity, etc. So each alien has to find a local animal (or animals) that they like and reshape themselves using that organism's biology. Because the aliens are humanoid in nature, they all maintain a humanoid appearance, but their secondary features all come from whatever Earth forms they supplement themselves with. So, while each alien is born looking the same, their different appearances are the result of advanced gene therapy necessary for living in our world. [Answer] Because we lack a subtle understanding of their features. If I look around myself in the office today I see many different homo sapiens: they are all homo sapiens, but just to cite two cases, Jim is tall, blonde, has green eyes and his body is covered in blue woolen fabric, while Janet is shorter, has dark curly hair, brown eyes and her body is covered in cotton fabric and synthetic fabric, plus some leather around her waist. Oh, I have just been told that homo sapiens uses something called "clothes" to hide their bodies because of a concept called "nudity", and also when naked their physical appearance changes a lot in terms of skin color, fat distribution, primary and secondary sexual characters, height and so on. [Answer] **Demon Bodies are Like Spacesuits** The demons are, ostensibly, from hell. Though with the "no magic but they have tech" caveat they could just as easily be aliens. But since you're calling them demons we'll assume that at a base level they're from another dimension. In that dimension, all demons look pretty similar. Their "souls" as humans would call them, ARE their bodies in their home dimension, and they're as uniform as human beings are on earth. When they cross over into our reality they need the "protection" of physical bodies. These bodies need certain baseline constraints (two arms, two legs, must take the shape of the "higher" animals such as birds/reptiles/mammals) in the same way that a human's spacesuit has certain universal constraints. But after that, the demon's body can be configured to whatever best suits the demons personal preference/operational needs. They don't change these bodies in our universe for the same reason an astronaut doesn't try to swap space suits/parts of suits mid-spacewalk. So while one demon has 8 horns and a goat's head and another had wings and 7 fingers on each hand, that's no different than comparing a NASA astronaut's suit with full maneuvering unit to a Russian Sokal suit. If you ever looked at the *actual* thing wearing it, they're pretty similar. I won't get into the details of demonic mating rituals on a family stack, but suffice to say that there is.... functionality to link bodies, and through the wonders of inter-dimensional travel a baby demon is insulated by the mother's body until it comes out with its own "suit" to live its own life. [Answer] **Magic doesn't exist? No problem!** This can be explained *genetically,* funnily enough. First of all, the existence of succubi/incubi in mythos. When sperm and egg meet, the result is the two chromosomes required to get a fully functioning human being, right? You'd think this can only happen with related species, but if [this](https://www.newscientist.com/article/dn4558-pig-human-chimeras-contain-cell-surprise/) is any indication, you'd be wrong. Add in biological gene modification (see [this question](https://worldbuilding.stackexchange.com/questions/110325/can-humanoids-be-reborn-from-a-tree)'s accepted answer for an explanation) and the existence of gene transfer *between species* through bacterial and viral vectors, and you have a pretty good explanation of sans-magic demons. In our universe, cells evolved to cooperate in such a way as to form complete organisms, relying on one special cell type to reproduce. In an alternate universe, however, a cell mass developed the means to 'mate by infiltration,' or to hijack the reproductive cell, adding in the infiltrating organism's DNA to create an alien hybrid as offspring. For whatever reason, these organisms have somehow traveled to and from our world, back and forth, through some sort of warp in dimensional walls, using native organisms as reproductive vectors, and the result was beings like the Chimera, or dragons, or mermaids-the result of these organisms sharing genes amongst their own kind. These organisms eventually evolved intelligence, and the ability to capture and add their DNA to ingested cells, and by this method they created incubi and succubi to add humanity to their collective might. However, much to their chagrin, the ways to Earth have been closed...until now...when a portal opened in Salem, Massachusetts, allowing the demon army to invade the world. Seriously, this stuff almost writes itself! If you don't use this idea, I know I will! [Answer] **Scenario, technology is the key:** They exist in a society (Demon world) which has for most of their history been prosperous. They started much as humans had, gradually growing, going to war discovering medicine until.... their technology gave them an edge so they could eliminate poverty, starvation, and manual labour (and most other work). Socially, the dominant trends in what preoccupies people's minds and time are fashion-based. The technology eventually developed to the point of allowing them to chose a form suiting their desires, in some locales, the feathered, winged type - more lightweight but fun to own, in others the lizard type, because it's "street" and intimidating, in others a furry feline look for the sleek graceful movers and the proud hunters, and others opt for a more human-like appearance but with other enhancements - horns or a skull bone-ridge. Of course, these can be changed at will, or kept if it's found to suite the wearer's personality. Occasionally, a "tourist" or adolescent seeking thrills would visit the human world and kick-off a local frenzy among a few villagers - rarely a criminal from their world would take it further. {Some great disaster befalls their civilisation, it collapses. Chaos, anarchy, lack of food, bloody hell. Of course, they're too concerned about survival to amend their appearance to anything making them able to blend-in. They look to Earth for a second chance.} Your story begins. [Answer] **Mutations and selected adaptations.** Maybe once upon a time this race from another universe had a more consistent appearance, but a combination of radiation from interdimensional travel, which led to the technology that allowed them to alter and repair their genetics, which then led to them being able to borrow traits from other creatures around them. Over the generations as these traits are blended as new individuals are born, things have gotten pretty chaotic. The wealthy elite alter things as they want, removing unwanted traits and adding desired ones, but it is an expensive and lengthy process, and so the less wealthy rely on luck, careful choosing of mates, and very rarely genetic alterations. The poorest only have luck to trust in, and it fails them more often than not. [Answer] **most of these features exist in their DNA** Just like species here, they have a lot of inactive DNA sequences for a lot of different features that can exist, but are just [non-coding](https://en.wikipedia.org/wiki/Non-coding_DNA). Those sequences can be activated with small mutations. EDIT: the reason they can have features that none of their ancestors had (features from other animal reigns, let’s say, insectoid features), is because of [Horizontal gene transfer](https://en.wikipedia.org/wiki/Horizontal_gene_transfer) **They mutate really fast** Most species here don’t mutate a lot. It wouldn’t be viable (since the probability of producing a non-viable specimen are way to high, it wouldn’t be cost-effective) The demon world is very different: Energy is no problem, there is hellfire everywhere. Plus high levels of radioactivity favorise fast mutations. Problem is species there are very violent, so it is a very harsh environment. Demons are the species that have evolved to survive by being unpredictable in their features (since predators will prefer to hunt what they know). An average demon will have tens of viable babies in a litter, hundreds of non-viable ones, all differents. The ones that actually look too different from human-like features are rejected socially though, so they cannot survive. In the end only one or two in a litter will reach adult age. [Answer] # They have polymorphic DNA, and can take the DNA of other mammals to enhance their form. Scales/skin or fur- pangolians have fur, and fur is common. Humanoid or animal heads- they can adopt the genetics of animal heads. Beaks or snouts- Snouts are common, and platypus and echidna have beaks. Wings or wingless- bats have suitably demonic wings as do several other species. Number of horns- Many mammals have horns. Skin/fur - There are many mammals with different types of fur. # They do hybridizations of reptile and avian species with a high risk of drastic mutations. Mammals are closely related to them, and easy for them to take DNA from. Reptile and avian species are much more distantly related. In the past some bad hybridizations resulted in terrible things like second faces on crotches. Some stable variations were found though, where the mutational difference was less. As such, there's a small but lesser number of demons with such features. # They tend to take genes from hox genes, and similar highly conserved gene clusters. These have been used in human experiments to make mutatant flies. Their ability to steal DNA lets them do this naturally, and have some sense of the likely outcome, enough for them to most of the time hybridize themselves to other mammals. [![enter image description here](https://i.stack.imgur.com/zA105.jpg)](https://i.stack.imgur.com/zA105.jpg) [Answer] # Scales/Skin or Fur Variations in where hair grows already exists in humans to some degree, with alopecia universalis and hypertrichosis. These traits, or at least something like them, could easily explain all the variance in hair cover that you'd want Similarly, the great variety of scaleless reptiles shows that variance on this scale is just as plausible # Humanoid or Animal Heads This level of variation is more-or-less already seen in the heads of dogs. The only thing further is the nose, which would need to vary between human-like, mammalian, and reptilian. Non-humanoid noses could simply be noses with very small cartilages as in animals, and non-mammalian noses could be explained as a mutation that deletes the rhinarium # Beaks or Snouts This feature seems the hardest to explain: All animals with beaks or snouts are very well adapted for their jaw type, and it doesn't seem plausible that a single species could use both However, you could 'cheat' this point; all demons could have toothy snouts, with some horny lips that approximate beak tomia. Then, the difference between beaked and snouted demons could simply be a difference in skull shape, with narrow pointed faces appearing as beaks, and wide robust faces appearing as snouts # Wings or Wingless There are many genetic variations that can cause issues to specific limbs. A common variation might cause issues in the wings that require them to be amputated at birth, or perhaps even to not form at all. This will give you a variable presence of wings # Number of Horns Many horned species already have a variable number of horns, based on sex. There is no reason not to use this system in demons # Skin/Fur Colors This variation is already seen in humans. And if that isn't variable enough for your purposes, then dogs show an even greater variety [Answer] Not mine idea, but still not quite the same as mentioned above. # Individual evolution The demons, in a strict sense, do not exist as a species. They are a conglomerate of species. Each individual demon has evolved / mutated to fit and counter *its* individual environment, in *its* own way. Similarities are due to convergence, dolphins and sharks are also similar enough, but have very different origins. Basically, if you dig deep enough, each and every demon is unique. Smile and say "hi" to [Lamarck](https://en.wikipedia.org/wiki/Jean-Baptiste_Lamarck)! ]
[Question] [ Of course, my question isn't about the existence of magic. It's about coherence of the story. Imagine two neighbouring countries. One of them resembles our society – it's science based, no magic, people have what we would consider 'rational' thinking. The society priors education, but they also have developed art, economy, military defense mechanisms, etc. The second bordering country is completely different. It is a feudal society, with technology set back decades. And in that world, 'magic' exists. The magic ranges in a wide domain. Some people are very powerful, they can use telekinesis on long distance, control weather, control chemical reactions in their bodies, etc. Others are much weaker, they can only manipulate things in a very short radius. Most cannot use magic, but that a minority can is accepted and is seen rather than a virtue than as a fault – so no witch burnings. The majority of the population, even though they cannot perform magic, is in any case passively adapted to its existence – for example, if air temperature drops drastically they would survive for longer than biologically possible, or they can tell whether the water is contaminated by the sight, etc. (I am actually trying to find some sort of sci-fi explanation for this magic, but that is off topic. The actual nature of magic is irrelevant to the question). My question is, would this scenario be possible? This separation of societies. The two countries are separated by a mountain barrier, so there is no – or close to none – interaction between the folk. Would it be possible for two close countries to have evolved this way, completely isolated from each other and having completely different laws of nature? Would the two populations be considered the same species? They obviously had a common ancestor, so would it be possible for one people to develop the 'magic' ability without the other one doing so? [Answer] Garth Nix's Abhorsen series is set in such a world and it is very believable. I'm sure you don't want yours to be too similar, but here's the gist: The two countries are separated by a large wall, not a mountain range. South of the wall, magic gets less effective, and it is entirely ineffective in most of the civilized regions of the southern nation unless there is some sort of incursion by a powerful magical being. Most of the machines of the south are not as effective where magic is effective. The magic is powered by the 'Charter' which is a joint effort by a group of godlike free magic spirits, and the power is stored in various artifacts in the northern region including the wall itself. This is why the magic is in the north and not the south, basically. The southern nation views the northern one as a third world country, not as a different species. The common citizen of the south does not believe in magic, having never seen it themselves, and thinks the northern kingdom is full of superstitious bumpkins. They are more concerned with other mundane nations. The north does not allow southerners through the wall, and both populations generally prefer to stay on their own sides. [Answer] Actually nature of magic **is** very relevant to the question. Your setting corresponds to the "rational" realm not having useable magic, while in the "fantasy" realm the ability of the social elite to use magic has retarded technological and social progress. Which is realistic, by the way. Innovations are adopted because they are needed, if the social elite has magic boosting its abilities many innovations in our world would have been unnecessary. And this **does** apply to changes to government. Nobility with telepathy and communication magic would govern a lot more efficiently than their counterparts in our world or in the "rational" realm. As for possible reasons for one realm not having useable magic while other realms do: **No power** Magical and even psionic effects are generally powered by external power, either a specific source or ambient magic, often called mana. If an area has no specific power sources and has a level of ambient magic low enough that only the most powerful magic user can do anything, that will give the general effect you want. In stories this typically is a result of some magical disaster or war consuming the local magic to the point where it will take centuries or even millennia to recover. It can also be an ongoing drain effect by some external power or a blockage in the natural flow of mana caused by causes natural or artificial. You mention mountains, maybe mountains block the flow of magic? **No activation** It is impossible or nearly so to bring the magical power in a form that can be used. This could be an interdiction by a god or powerful spell or a strong and persistent turbulence in the flow of magic. In this scenario magicians trained elsewhere could carry talismans that stabilize the magic or exempt them from the interdiction and cause a rude surprise to the locals. A powerful enough magician might have a personal aura powerful enough to exempt him. **No control** Similar to the above, but the issue is in controlling the effect not in making it happen. This would still make magic impossible to learn, but a skilled mage trained elsewhere might have enough control to use magic. This could make potential mages dangerous to be around and cause natural selection away from magical talent. [Answer] Most of the answers seem to focus on giving some mechanism by which magic doesn't work in the technological country. No such mechanism is needed: culture is enough. Just consider guns in our own world. Every country has the ability to obtain guns, either by making or buying them. Yet, in some countries, many people have guns but, in other countries, essentially nobody except the military and police have guns. Quite often, in the countries where many civilians own guns, many people have an unshakable belief that owning guns is absolutely necessary to having a functional society and they cannot comprehend how a society could possibly function without them. In the countries where few civilians own guns, many people have an unshakable belief that banning guns is absolutely necessary to having a functional society and they cannot comprehend how a society could possibly function *with* them. Now, replace guns with magic. There's a slight difference in that societies with few guns still have armed police, militaries and some civilian use of guns (e.g., sport, rural pest control, perhaps hunting), whereas you're talking about a society with no magic at all. One way to explain that is to argue that the police and military simply don't need to use magic – shooting firebolts at somebody isn't so useful if you can just shoot bullets. Another possibility would be that the government security services and maybe special forces use magic but this is largely hidden from the population or accepted by them in the same way that people in societies with few guns accept that the police and military need guns. By the way, what *does* seem infeasible about your set-up is not that one of these countries uses magic and the other one doesn't, but that they have such huge disparity of economic, social and technological development, despite being so close together. [Answer] Yes. The most rational way is if raw magic is a substance associated with certain rare minerals and exploitable by people with certain rare inherited traits after careful training. The magical country sits atop rich seams of raw magic and has a magically inclined population. The other one doesn't. The population thing may be Darwinian: if someone lacking the genetic traits ( and/or training) is tempted to experiment in a high magical field, it is usually fatal to him. I'm tempted by the "cannot use magic on iron" trope. Maybe the non magical country sits atop ironstone which protects it from magical attack and means that it's found its way to an industrial revolution. The magical country has no good iron ore. Hence trade not war. And of course, mages make appallingly bad technologists. They expect to magically impose their will on matter, not to carefully observe matter to see how it would like to be of assistance. Put like that, maybe the non magical country is actually home to a different, subtle sort of magic. [Answer] From a sociopolitical point of view, it is possible - look at [pre-Perry](https://en.wikipedia.org/wiki/Perry_Expedition) Japan, being for 2 centuries in almost complete isolation (surrounded by sea, which is quite more amenable to trade than a mountain range). At the beginning of their seclusion, they were technologically quite comparable to "the west", only very slightly behind. Then they lagged behind, one can say by rejecting western influence, science, technology and contacts. To some extent, this also applies to 19th century China, but they were not as isolated and western powers kept meddling. [Answer] Depending on where you want to go with this story, I would try a divine-intervention angle. > > In a time long before anyone can remember, one people blessed by the Gods, another cursed. One ruled by the rational, the other by the arcane... > > > From your descriptions, it is entirely ambiguous which is blessed and which is cursed. If you leave it that way deliberately, it can make an interesting twist for your readers to contemplate. [Answer] The problem with magic and technology coexisting is that technology is so painfully *fragile*. Any gas tank is a fire ball waiting to happen. Any fast spinning engine can be easily destroyed by a very small and undetectable spell. And so on. In one county, incidents like this has lead to a witch hunt and any mages has either been killed or fled to the other country. In the other country mages hold power and have suppressed any technological development since they see where that sort of thing leads. The two countries are not likely to be on good terms. A war between them could turn very ugly. [Answer] I figure you have two broad options: one country gains magic or one loses it. They don't have to start with either magic or technology, perhaps they develop side by side. Anyway, here are some ideas.... ### Gaining Magic Given that you have expressed a desire for magic to be explained scientifically, having one side of an age-old conflict develop a technology that appears the same as magic would perhaps explain why both sides don't possess it. Only those inducted into the control mechanism of the magic can leverage it in any way. Perhaps there is an implant or imprinting that is required before they can access the magic. Depending on how high tech you want the world to be at the time of your story you could have the advent of magic result in a near-apocalyptic war between the two nations, resulting in both being essentially beaten back to the stone age. The technology behind the 'magic' survives an enough people who know how to use it maintain the ability for the country as a whole. Or perhaps the ability to use magic is gained as a mutation in a single genetic lineage. Genetic markers are another mainstay of magic use in a variety of SF&F, from the Comyn of Darkover to the Scions of Shannara. Specific genetics could translate to physical structures allowing one group to access magical energies and perform feats of magic that others cannot duplicate, with an obvious survival advantage making the gene more likely to spread. Users of magic might be ostracized and driven out, eventually forcing them to flee to their own country where they can practice their magic in peace. ### Losing Magic This one gives you lots of room to play with. Assume that everyone has the ability to use magic at some point, now all you need is for one group to be somehow cut off from that ability. For a technological magic there could be any number of ways that one group could be cut off, from the institution of security controls to the destruction of interfaces, perhaps even some sort of genetic key that someone must possess before they will be accepted by the technology (such as the Ancient gene in Stargate). The use of magic might be restricted to a small segment of society - reserved for royalty or a priest class for instance - which is eventually corrupted to the point that they are overthrown by the peasant class. Everyone would potentially retain the ability to do some small magic, but none would have the training or ability to perform great feats of magic after potentially many generations of being forced not to. Or perhaps the church decides that all magic is wicked and actively suppresses it wherever it is found, resulting in all magic use being stamped out in the area controlled by the church. Given enough time and strict enough suppression of magic, the whole area would be essentially devoid of anyone able to use magic. ### Some (not particularly original) ideas on Tech Magery Whether you're the Ship Who Won finding a world full of mentally-controlled alien machinery (and the humans who have stolen it from the rightful owners), a shaman in ADF's Cyber Way or a resident of the Well World technology as magic is far from a new idea. Here are a few concepts that I've seen done with varying degrees of success: 1. Magic is a byproduct of alien technology that was intended for some other purpose but hijacked by humanity for selfish use, or subtly altered from its original purpose to serve as a font of power for certain people. (The aforementioned Ship who Won for instance.) 2. Science discovers that the universe is simply information and that it is possible to directly modify that information, sometimes only briefly, to produce some interesting effects. (The Ship of the Law from Anvil of Stars uses this.) 3. The world that the story portrays is a computer simulation running on some super computer, and all the people are simply unaware of this. Magic is what you get when you manage to get some control over the simulation. (You know, like the Matrix.) 4. A super-powerful computer (possibly the entire world) that is able to manifest physical-seeming fields of force (Holodeck-style) that are used to simulate the effects of magic. (Markovian ruins in the Well World saga, or the computer in [Cyber Way](http://www.goodreads.com/book/show/171506.Cyber_Way).) 5. The universe is actually a projection maintained by a computer. Rather than being a simulation the computer is warping reality with its power. Interfacing in some way with the universe's control center gives you anything up to god-like power. (Especially if you're Nathan Brazil) 6. Engineered nano-machines allow anyone with the right mental keys to order them to do things, but nobody remembers that it's tech based or that the nano-machines even exist. The nano-machines have limited power but there are a *lot* of them, in everything, and they are quite happy to use your mitochondria as a power source, so don't draw too heavily. (Read [Spell of Catastrophe](http://www.mayerbrenner.com/) for this one.) 7. Magic is simply latent human psi amplified by some suitable device, be it a Darkovan star-stone or some other technological psi amplifier. I'd say that the Tower and the Hive stories qualify here, although the amplification is actually done by the psi users themselves by drawing on electrical power, and they don't *call* it magic, but let's not quibble. (The device in The Forbidden Planet perhaps?) 8. Probability mechanics allows humans to manipulate reality in magical ways by changing the odds of things happening. By altering the odds of really bizarre things happening in a very small area and with just the right impetus you could cause any magical effect you can think of to become 100% likely to happen. Of course you'd need a computer the size of Jupiter to get all the calculations down just right. (Watch out for spontaneous Sperm Whales.) 9. Finally, the catch-all: It's science, but it's so advanced that I can't even begin to describe how it works. Just take my word for it, it's science, not magic. Honest. (If you can't find an example of this, you're not looking hard enough. Try Rama, or the Xeelee Sequence, or pretty much all of Known Space.) [Answer] Magic works the way the author wants it to. So I am just going to answer the non-magical question. I understand it to be is it possible to have two culture that is geographically very close but does not interact. I give you the Anglo community of Gibraltar they live at the tip of Spain and get most of their food from England. They have one road that goes to Spain and you have to cross the airstrip to use that. So my answer is no problem. [Answer] To maintain separate countries even with a barrier, you'd need the magic to be militarily equivalent to the technology. This isn't traditionally the case, against a low tech society magic is normally dominant. The wider distribution of technology would later make the high tech society dominant. Don't forget [armies with elephants have been marched over mountain barriers](https://en.wikipedia.org/wiki/Hannibal's_crossing_of_the_Alps), people will cross back and forth, no matter how hard. Add magical supply lines and crossing the mountains isn't so hard, two thousand years later and the bombers make light work of the same mountains. You could say that the magic interferes with the technology and vice versa. Too much magic and your experiments come out wrong, technology can't develop. Too much electromagnetic noise from technology and you can't focus on the magic. Since the two cultures went in different directions from the start they now can't switch over. High availability of magic tends to make technological development redundant anyway, why develop a machine when you can wave a hand. Technology for us is also driven by the needs and wants of the middle classes, a feudal society wouldn't have that drive. Why develop the microwave when you have serfs and servants? [Answer] First, in order to answer your question, I'll have to assume out the most generic differences between magic and technology: 1. Unlike technology, **magic contains an unavoidable personal component**. This means that you can never guarantee obtaining exactly the same results. If that were untrue, there wouldn't be any real distinction from magic and technology. In generic settings, that personal component is significant. 2. Even well-developed **magic is more dangerous** than developed technology. Using magic is akin to using a raw tool with most safeties stripped off. Because you can't have pre-engineered, tested and fool-proof magic safeties for the aforementioned personal component. 3. **Magic is inherently unequal.** In your case, this is stated outright. What if the matter of using magic is not one of ability, but that of morality? **Magic has a price** Suppose that the magic requires some sort of sacrifice, or simply can go out of control and harm others. In a feudal society, where inequality is great and life expectancy is low, magic can be seen simply yet another tool with unfortunate but acceptable side effects, like alchemy was in our Middle Ages. On the other hand, in a society with more modern views on personal rights, and where people tend to live to old-old age, something so reckless as using magic can be seen as the most amoral and asocial behaviour, akin to suicide bombing and drone strikes. Any safety inspector that catches a slightest whiff of magic arrests the one responsible at once. **Magic requires indoctrination** On the other hand, what if to be successfully used, magic required immense training from the childhood and unwavering control? A feudal society has no trouble with imposing pre-determined roles from the first years of life, and people would have no qualms about making a child train 16 hours a day and turning into a drone whose only purpose is to cast magic. On the other hand, an *ideal* modern society would stop a child from overexerting herself, and maybe if you don't train hard enough in first 5-6 years of life, you lose your magic abilities and can't return them with no amount of practice later. **Magic is seen as unfair** What if the first country had its magic users in the past, but lost them? Maybe a revolution that led to the current society was organised by the not-haves, and now that they are in control they can ensure that everyone plays fair and with no weird focuses, say, by dispersing an anti-magic reagent in water supplies. --- Since there seem to be a miscommunication about what is 'magic' and what is 'science', I'll elaborate a bit on that. In the above answer I've assumed (I guess wrongly) that you are opposing magic and science. That is, that your magic is not subject to scientific method. If that is untrue, then 'magic' isn't really magic, it is simply a yet unknown law of nature, that can be studied. Societies do not possess "different laws of nature", but you can make one area subject to some phenomena that is unobservable in the first country. It can be some sort of Unobtainium radiation, or whatever you want, it can even modify living tissues giving 'magic' abilities and adaptation (like Mass Effect biotics). [Answer] Katherine Kurtz' *Deryni* series makes magical ability mostly a matter of genetics, then adds a religious proscription in one country (but not its neighbors) which drives the magic-capable population out or underground. [Answer] In a french cross-media universe (with books, series and films: search Neogicia) there is that kind of separation. Here is how it has been done : * Magic is available to everyone with inequalities (some are gifted, other are not, you re not always taught to use magic) * Magic is extremely powerful and the users not always clever (likely to blow things up while fighting each other) * One day some magic users "accidentally" blow up someone's family, this someone happens to be upset about that and willing to spend his near unlimited-inherited resources and his whole life to exterminate what made him an orphan * "wait but MAGIC is responsible for my beloved death so I shall destroy magic!" * "but how do I destroy something that can turns me into a human torch from a 1 mile range?" technology was born * the guy start to build a lab and push science forward, more and more people get interested in this utopia of world without magic, after some generations technology has evolved at an exponential rate, ultimately leaving it able to compete with magic. A city is built around the lab, one you can see in sci-fi novels. At the same time the guy's great great great grandson finally find a "cure to magic" able to remove someone's bonds to the spiritual plane (if this person wants to). While giving them some psy power and ability to use advanced tech * at the same time magic still works but people deliberately chose to ignore it while other just didn't care about this "technology" at all, why would they care about something that bring nothing that magic can't do? (moreover the leader is creepy) Well they started to care at some point (remember the guy wants to destroy magic?) but way to late since no one ever thought that destroying magic was possible (just like if I told you "I hate electromagnetism because I hate it so much, now I shall destroy electromagnetism in the whole universe because I'm mad and I hate mwahahahah") Could be a good start for you. Since the technology has been built with some knowledge of magic it's rather magic-proof and not likely to blow up at the first fireball. They created anti-magic shell, magic-free fields and other magic altering things. Everything that alter the physical is therefore part of the physical world so it is subject to science. Even if they deliberately decided to not USE magic (they even removed their ability to do so) they ended up understanding magic better than magic users. [Answer] Ok here one scenario The knowledge of know to use magic is reserved for the ruling class. Thousands of years ago during a magic World War war between light and dark magic. During the war group of peasants fed up with the death and destruction the war had brought blame their magic music leaders. Because of this they leave cross the mountains to establish a new nation. In this new nation the use of magic is playing for causing the war and since the population of peasants most of them don't know how to use magic anyways. Because of this he began trying to build tools that will help them compensate for the lack of magic. This eventually leads to and industrial revolution. The eventually become advanced enough can we contact the other side of the mountains. When the nations come into contact with each other again. Magic users are suspicious of the other sides technology. There are also resentful that their ancestors abandon them in the middle of their war against evil. Because of this they strongly discourage their people from interacting with the people from the other side of the mountain or using thier technology. Some technology still manage to cross over but those that uses it on shunned by rest of society, because of this most people that use technology is associated with criminal activity. Meanwhile on the other side the people blame magic for the cause war. In history class magic users are portrayed as monsters. The fear of magic deters people from crossing the mountains. [Answer] Magic requires some resource hoarded by the cultural elite (mana, intensive education [although a physical resource makes more sense], etc) and is an intensely guarded national treasure. Their City-State is built by providing for their citizens, but not allowing them social mobility. Meanwhile, other civilizations maintained normal progress outside the borders; the magic country has presumably reached it's maximum capacity for warmongering or size. From here you can probably just treat them as two separate technological paths with different characteristics or rates of growth. Is magic 'stuck' as the same or does it keep progressing alongside technology? [Answer] Two close countries that are in different stages of development are very possible. Africa would be a good place to look into. Inciting hostilities between two very different nations wouldn't be all that difficult. Work off of xenophobia. Both cultures are in very different stages of development. The magically gifted society wouldn't understand the non-magic society's technology and you could introduce someone or many people in a position of power so frightened of this seemingly alien race that he/she/it/they encourage their nation to reject the non-magicals. Or you could set it up so that one culture has something the other wants, and for whatever reason won't trade. Currently we're getting to a point where we will be unable to produce enough food for everyone, so why not set it up so that, say, the magical nation has a way of artificially increasing a crops yield two or threefold and storing that extra food indefinitely, but for whatever reason cannot or will not share it. If you play on the cultural differences between them you could set up a situation to incite hostilities between the two countries. [Answer] Yes, it can be done - and if the answers to this question are any indication, there's lots of ways to do it! My favorite (and personal head-canon) of the ways magic and science can be both possible and incompatible comes from "[Stranglehold](http://hell.pl/szymon/Baen/The%20Baltic%20War/Interstellar%20Patrol/0743436008__15.htm)" by Christopher Anvil - where the problem comes from fundamentally incompatible worldviews. So despite a setup where anyone from either city is the same species with the same capabilities, capable of creating generally the same kinds of effects, and so (technically) capable of using either approach - in practice each can't understand the other's worldview, and considers each other dangerously insane. Magic almost always requires some personal component, they have to want it, will it, to happen. What they can do with that depends on talent, strength, and various other limiting factors depending on how magic works and what it does in that universe... but they always have to want it, and can't do things they believe they cannot. Science depends on dispassionate observation, where doing the same thing always (or even nearly always) produces the same results. Without that assumption, there's no way for the scientific method to catch on. If currents can flow either way, or objects fall faster or slower based on what someone wants or believes, there's scientific experimentation that will work. If whether a spell works or not depends on the will or belief of the person casting it, an experiment can fool around with visible components and chants without ever realizing the missing factor. And as a bonus... each society would consider the consequences of each other's worldview to be immoral. Scientific society would consider the magic-users' backwards, superstitious, lazy, willing to accept all kinds of inequalities, since magic talent is unequal, access to magical training might be restricted, and the society is more hierarchical. Magical society would consider science-users crazy, superstitious, and cruel - they might consider scientific education responsible for the inability of science people to do magic (crippling their own children!) or maybe trying to rewrite reality (do they think if they can get enough people to believe these 'science laws', would that act like a spell to rewrite the universe?! Crazy science-people!) So science-users and magic-users are going to want to stay separate, once they find each other. The mountain ranges, or whatever physical barrier that lies between them only has to last long enough for each to get a head start on their respective worldviews - then the 'technological' incompatibility (that their respective strategies both didn't make sense to, and didn't work with the other's people) would keep the cultural incompatibility pretty high. The occasional traveler would have unbelievable stories, and depending on the history might have been considered insane, or to have visited a people who were all insane. And then both societies progress far enough (in their own ways) to transverse the mountains...and find each other on the other side. Probably with a "boom!". So if you set up something like this, you can have protagonist peoples who are really similar to each other, and even have the same theoretical capabilities, and still have that absolute social divide. As a bonus, you can have conflict on lots and lots of levels - even those trying to work with each other in good faith are going to find the cultural divide enormous and with all kinds of shocking surprises and moving goalposts. And if one side wants to find the unobtainium to harness both powers, there's lots of room for conflict, setbacks, or outright impossibility without losing authorial wiggleroom to make the powers work together in other ways. [Answer] David Weber and Linda Evans wrote a 3-book series (Hell's Gate) with two societies, one magical and one technological, brought into contact and subsequent conflict that explores this juxtaposition. Two worlds developed completely independently, one with the same scientific and technological orientation as ours, the other with no science as such, but instead a well-developed magic using ability (including telepathic use of dragons). The two worlds are thrown into juxtaposition by the opening of gates that permit immediate transport from each world to a third. The two societies each begin to explore the new world from their respective gates. Through accidental contact the initial parties startle each other so badly that they each use their respective powers in defense and thereby badly frighten each other. Each society throws more resources (magic, technology) into the mix and the confrontation escalates because neither side has the wherewithal to understand the reactions of the other. It was the use of the gates which allowed the two fully developed societies to encounter each other unexpectedly. ]
[Question] [ This question is inspired by *[Mortal Engines](https://en.wikipedia.org/wiki/Mortal_Engines)*, but I imagine something more feasible. The original question I wanted to ask was "How to keep a city in the air?", but I figured out there is another problem - I don't know how big, and heavy, it needs to be. As to why - tax-free zone, poor housing situation on land, etc. are among many great reasons to have a town not connected to a specific territory, but instead to put it in the air or over international waters. Recent AI limitations that made companies plan to put tens of thousands of GPUs on international waters, [even if it is just an elaborate hoax](https://www.extremetech.com/computing/ai-company-plans-to-run-clusters-of-10000-nvidia-h100-gpus-in-international), are yet another good idea to build worlds around. Was it ever estimated how much mass per X amount of citizens is needed? If there are ready-made analysis available, I'll consider them valid answers. If there are not, here is what I want: * 2000 people because that's the lowest limit of what can be considered a town where I live. Also, this sounds like a good number. * Single family apartments in "houses" that consist of up to a dozen apartments. * Water, electricity and municipal heat grids. * Sewage system with water reclamation, to minimize supply lines. * Public areas, even if minimal ones, because [Kowloon](https://en.wikipedia.org/wiki/Kowloon_Walled_City) showed us that such paces will happen. * Places of employment (offices, workshops, etc.) for at least 80% of working age population. * Basic education and healthcare. * Supplies for at least a month of operation without resupply. * Transportation (walkways, lifts, etc.) * I want it to feel like a town / city, not a big ship. * External income should come from businesses that are heavily regulated elsewhere, like biological research, AI research, diamond and luxury goods trade with countries under international sanctions, etc., and from being a headquarters of companies with multi-million dollar incomes. What I **don't** want to calculate yet is: * Growing their own food. * System to keep it in the air, afloat or whatever. * Propulsion. * Electricity production. * Basically anything that wouldn't be in a traditional city. [Answer] Let's establish some upper and lower bounds. The ISS is a self-contained ultra-lightweight city for 7 people. Wikipedia tells me it weighs 450 tonnes. So for 2000 on a super-ISS we can extrapolate to 128,571 tonnes. The tiangong space station has a crew of 6 and a estimated mass of 100 tonnes, so we can extrapolate to 33,333 tonnes. Now these are very optimistic. Linear scaling of mass may work in space where you don't have to worry about gravity, but here on Earth most things follow the square cube law. Also, these are engineered to be launched into space at astronomical prices. A earth-bound-city is likely constructed of inferior materials. Either way, your city is almost certainly going to weigh more than 30,000 tonnes. Cruise ships run in at 170,000 tonnes for 2000 people, so heavier still. For reference, this is heavier than the Bagger288, the heaviest land vehicle which weighs in at only 13,500 tonnes. --- So what about an upper bound? For this let's just lift an existing city in it's entirety, dirt and all. The township of Methven, New Zealand has an estimated population of 2010 people, and wikipedia has it listed at an area of 4.18km2, or ~2000m x 2000m. So let's scoop it up. Let's be generous and take all it's land as well, to a depth of 20m. This ensures we get all the infrastructure and peoples basements. We now have some 80 million cubic meters of (mostly) dirt. A quick google suggests 1.5 tonnes per cubic meter for a total estimated mass of 120 million tonnes. So there we go, your town if constructed of aerospace grade materials with super-cramped living conditions, could weigh in the tens-of-thousands of tonnes. Or if you picked up and moved an actual village it would be in the hundreds of millions of tonnes. --- Side note: > > I want people to live there, so they need to have homes, not cabins. > > > People adapt to what they live in. Many many people live in apartment blocks rather than suburbia. I have no doubt that future people who live in space stations would feel uncomfortable in a modern family suburban home just due to how much free space it has and how many openable windows it has! I definitely got used to living in a single-room apartment that measured only a couple meters square, and here in NZ, due to the building regulations, many people live in 'tiny homes' of under 30m2. [Answer] ## 200,000 tons. **Can be reduced to ~25,000 tons for a traditional Japanese town with minimal facilities.** *Good news:* your question is actually answerable scientifically! When building cities today, one has to hire a geologist to determine if the bedrock can take its weight. So there's a lot of ready-to-go estimates. *Not so good news:* since they have to hire a geologist to determine if the *bedrock* can take a city's weight, traditional urban construction is generally too heavy to be supported in the air. This paper includes such an estimate for NYC: <https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF003465> **Exact figures:** > > Live load requirements vary for different intended uses, from single family homes (0.48 kN/m2) to office buildings (2.4 kN/m2), up to heavy manufacturing facilities (11.97 kN/m2). > > Flooring dead loads range from 0.1 to 3.5 kN/m2. Reinforced concrete ... 2.0 kN/m2 value for dead loads. > The calculated cumulative mass of the buildings in New York City is 7.64 · 10^11 kg (1.68 trillion pounds), which is distributed over a 778.2 km2 area. > > > Averaging a neat ~1,000 kg/m2 or 100,000 kg per person. For a city of 2,000, that is **200,000,000 kg.** This is based on the actual city of New York. **Can it be lighter?** Live loads are the useful stuff, like people and items inside a home. Dead loads are building weight itself. So, a lightweight, suburban style environment can have a lower density, but never less than 60 kg/m2. This would be extremely light construction. Think single-story Japanese homes with Shoji paper walls. Let's assume you need at least 100 m2/person - this includes streets, yards, plus floor area, and would represent a twice denser than average suburban construction of 0.1 acre per family of 4. That gives just 6,000 kg/person to support. At that weight, the live load for a city of 2,000 could fit into just **12,000 tons**. However, the 12,000 ton estimate doesn't include anything except the living spaces. Everyone would have to work from home and get stuff delivered by Amazon drones from somewhere else. Doubling it sounds like a conservative minimum. It's possible to go even lighter, but not realistic. Note that Shoji homes will not stand up to the rigors of flight, even at a relatively low altitude. The support and protective structures will take a lot more mass. [Answer] > > Cloud Nine is the name Buckminster Fuller gave to his proposed airborne habitats created from giant geodesic spheres, which might be made to levitate by slightly heating the air inside above the ambient temperature.[1](https://en.wikipedia.org/wiki/Cloud_Nine_(sphere)) > > > Geodesic spheres (structures of triangular components arranged to make a sphere) become stronger as they become bigger, because of how they distribute stress over their surfaces. As a sphere gets bigger, the volume it encloses grows much faster than the mass of the enclosing structure itself. Fuller suggested that the mass of a mile-wide geodesic sphere would be negligible compared to the mass of the air trapped within it. He suggested that if the air inside such a sphere were heated even by one degree higher than the ambient temperature of its surroundings, the sphere could become airborne. He calculated that such a balloon could lift a considerable mass, and hence that 'mini-cities' or airborne towns of thousands of people could be built in this way. > > > A Cloud Nine could be tethered, or free-floating, or maneuverable so that it could migrate in response to climatic and environmental conditions, such as providing emergency shelters.[2](https://books.google.com/books?id=iOhrizYNIjQC&q=cloud%20nine%20tensegrity%20sphere&pg=RA2-PA190#v=snippet&q=cloud%20nine%20tensegrity%20sphere&f=false) > > > <https://en.wikipedia.org/wiki/Cloud_Nine_(sphere)> [https://books.google.com/books?id=iOhrizYNIjQC&q=cloud+nine+tensegrity+sphere&pg=RA2-PA190#v=snippet&q=cloud%20nine%20tensegrity%20sphere&f=false](https://books.google.com/books?id=iOhrizYNIjQC&q=cloud%20nine%20tensegrity%20sphere&pg=RA2-PA190#v=snippet&q=cloud%20nine%20tensegrity%20sphere&f=false) See answers to this question: [Can Cloud Nine be built?](https://worldbuilding.stackexchange.com/questions/36667/can-cloud-nine-be-built) What you need is to find some calculations relating to hypothetical "Cloud Nine" structures. One problem I see with "cloud nine" structures is their spherical shape. If one loses lift due to leaks or something, and descends to the ground all its weight will be held up by a small section of the bottom which probably won't be strong enough and will probably break. Landing in water would enable it to submerge a large proportion of its volume and then float supported by water over a larger area, less likely to break the sphere. But water pressure increases rapidly with depth. If a mile wide sphere extends hundreds or thousands of feet below the waterline, the water pressure might break the lower sections of the sphere. I also wonder what would keep a sphere from tipping over and floating upside down in the air, while the people all plummet to their deaths. So perhaps the floating city would be designed as two hemispheres side by side instead of one full sphere. Maybe the living spaces of the city could be in a series of large but relatively small hemispheres arranged around the perimeter of a giant geodesic sphere for lift. For maximum surface area within a giant sphere, the floor area should be a circle at the "equator" of the sphere. If the buildings are tall, that will put more weight in the upper half of the sphere and make it more likely to be top heavy and tip over. Perhaps the buildings would all be one story above the "ground", with multiple stories of basements below the "ground", and with water storage in tanks below the "ground" level, etc. Thus the lower hemisphere may be heaver than the upper hemisphere to avoid tipping. How would the "ground", a circular disc a mile in diameter, be supported? By cables from above, like a suspension bridge, or by supports from below? Either way should add a lot of weight to the town, which might make it too heavy to float. Possibly There could be a relatively smaller circular area of "ground" right above the bottom of the sphere, and the tops of the buildings would support another and slightly wider layer of "ground" above it, and the buildings on the second layer could support a third, somewhat wider, layer of "ground", and so on. And the highest levels of "round" might be ring shaped, going around the perimeter of the sphere and with open spaces in their centers. Each ring would have a greater diameter than the ring below it. Thus the layout of the floating city would somewhat resemble that of Hell in Dante's *Inferno*, a set of concentric rings which get narrower and narrower at lower levels. The levels would be connected by ramps and elevators. Or the layout of the floating city could be said to somewhat resemble the layout of A.E. Van Vogt's spaceship the *Space Beagle*, or the Death Star in *Star Wars*, except that most of the floating city would be empty space with the "decks" or "ground" filling only only small part of the total volume of the sphere. To save weight, parts of a floating city, whether a "cloud nine" type geodesic sphere or some other type of design, might be made of aerogels. > > Aerogels are a class of synthetic porous ultralight material derived from a gel, in which the liquid component for the gel has been replaced with a gas, without significant collapse of the gel structure.[1](https://en.wikipedia.org/wiki/Cloud_Nine_(sphere)) The result is a solid with extremely low density[2](https://books.google.com/books?id=iOhrizYNIjQC&q=cloud%20nine%20tensegrity%20sphere&pg=RA2-PA190#v=snippet&q=cloud%20nine%20tensegrity%20sphere&f=false) and extremely low thermal conductivity. Aerogels can be made from a variety of chemical compounds.[4](https://en.wikipedia.org/wiki/Aerogel) Silica aerogels feel like fragile expanded polystyrene to the touch, while some polymer-based aerogels feel like rigid foams. > > > Despite the name, aerogels are solid, rigid, and dry materials that do not resemble a gel in their physical properties: the name comes from the fact that they are made from gels. Pressing softly on an aerogel typically does not leave even a minor mark; pressing more firmly will leave a permanent depression. Pressing extremely firmly will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass (a property known as friability), although more modern variations do not suffer from this. Despite the fact that it is prone to shattering, it is very strong structurally. Its impressive load-bearing abilities are due to the dendritic microstructure, in which spherical particles of average size 2–5 nm are fused together into clusters. These clusters form a three-dimensional highly porous structure of almost fractal chains, with pores just under 100 nm. The average size and density of the pores can be controlled during the manufacturing process. > > > <https://en.wikipedia.org/wiki/Aerogel> So in a world where aerogels are cheap and plentiful, and where people build floating cities, aerogels would naturally be used to build the parts of a floating city which they were most suited for, to reduce the weight. For example, I can imagine that aerogels might be useful for most of the parts in a building, so that the buildings in the floating town might be mostly made of aerogels. And if the buildings in the floating city are mostly made of aerogels that would greatly reduce the total weight of buildings to be calculated. Aerogel balloons have been suggested, Air filled aerogels are very light, but heavier than air. But if an aerogel could hold a vacuum, it would be lighter than air, and thus a solid but vacuum enclosing aerogel could be a lighter than air balloon, and maybe make a floating city. <https://discover.lanl.gov/publications/1663/2021-august/lighter-than-air/> Since aerogels are very strong, and also quite transparent, they could also be used for fake floating cities. Aerogel columns could support a city far above the ground. if someone could manage the lighting so that the columns couldn't be seen, it would look like the city was floating in the air, held in place by fake tethers to the ground. So a conman might claim that the city was temporarily tethered in place, and that after it was settled by his customers, it would be set free to float in the wind. [Answer] I remembered [an older question where the OP asked for the energy output of a city falling from 10km](https://worldbuilding.stackexchange.com/q/154574/21222). To answer that, I found an estimate of the mass of New York City. With the estimate I also found the methods used to get the numbers. [Here is the original article with the estimate and methods](https://www.thrillist.com/culture/how-much-does-manhattan-weigh). It has some interesting pieces of info, for example on street mass: > > Streets average 63 feet in width, sidewalks about 15 feet. Asphalt (streets) and concrete (sidewalks) each weigh a little over two tons per cubic yard, and each street needs at least three inches of asphalt on top. > > > Once you figure out how many km of street your city has, you can calculate volumes and plug in the densities. And for buildings: > > For buildings over 30 stories, use 3,000 tons per floor. Buildings under 30, use 200. > > > You still need to figure mass for people (a fixed number in your case), pets, vehicles, food etc. you havenin the city, and then estimate masses for those too. The article in the link has some ideas for that. I really don't have a number on top of my mind, but I hope the ideas above help you figure out some realistic mass. Next thing I would do is finding one or more towns with about 2,000 people living in them, and then trying to figure how many houses, streets, vehicles etc. they have in them. One place that comes to place is Westlake, in Alberta, Canada. It had a population of 2,040 people in 2021 and you can see it in Stree View in Google Maps. [Answer] # 5000 tons A lot of the questions assume just taking either a land-based city or an ocean-going ship and lifting it in the air. However, literally nobody would do that unless they had a way to lift things up in the air which didn't depend on weight (eg: neutralizing gravity). The better reference point is aerospace designs. Space stations like the ISS are not a great reference though, for different reasons: they include (very heavy) life support systems which you wouldn't need in the atmosphere, and (also very heavy) power systems. Here you're probably going to handle both life support and power separately, you're looking for just the living spaces and everything in them. Let's start with a modern large airplane: [Airbus A380](https://en.wikipedia.org/wiki/Airbus_A380#Specifications_(A380-800,_Trent_engines)). Usable area in the interior: 550 square meters. Max payload: 84 tons. Max passengers: 853 (very cramped of course). Empty weight: 285 tons, max takeoff weight: 575 tons, fuel capacity 253 tons. The engines are about 25 tons, not sure how much the wings are (probably pretty substantial, ~half of the total weight?). So a structure built in the same way as an Airbus would have roughly 1-3 tons of structure per ton of payload, and 0.25-0.5 tons of structure per square meter. Now the payload: obviously people themselves (2000 x 0.1 tons each = 200 tons). Furniture? appliances? a lot of that stuff would again be optimized for weight; foamed plastics, foamed metals, carbon fiber. People routinely go backpacking with a load < 20% of their body weight, and sometimes as little as 5 kg (ultralight). Let's be a bit generous and give a total weight budget for a longer term habitat roughly equal to body weight (also 0.1 tons each = 200 tons). So we're looking at ~400 tons total payload. Applying the ratio above would also give 400-1200 tons structure to keep that in. How about floor space? Average living space in Tokyo is 20 square meters per person (and for many people less than 10). The minimum recommended under very cramped living conditions is around 5. Take 2000 x 5 square meters = 10000 square meters x 0.25 - 0.5 tons per square meter = 2500-5000 tons of structure. So it seems the required weight of the structure is driven more by the floor space, less by the payload weight. Now, the big reason why the Airbus is not a good model: it is meant to go fast, almost at the speed of sound: Mach 0.89. This puts *huge* dynamic loads on the structure, which is designed for a lot of worst-case scenarios (flying through heavy turbulence at max speed). I think slow-flying big planes, and especially dirigibles, are built a lot lighter. Ideally you'd want to get specs for a dirigible (just the gondola, not the total including the gas bag), and do the same kind of analysis. Those specs are a lot harder to find, but eg the [Hindenburg](https://www.airships.net/hindenburg/interiors/) was about 118 tons empty and had around 700 square meters usable space on the passenger decks; however the vast majority of the weight was in the hull, I doubt the passenger space accounted for more than 1/10th of the total weight; the horizontal cross-section area of the whole gas bag was >5000 square meters. So an airship would probably be a lot closer to 0.01-0.02 tons of structure per square meter of deck space. I think ultimately you'd end up designing quite a lot more extra space, but in a much lighter (airship-like) structure: ie you'd end up with 20-50 square meters per person or even more, but still close to 5000 tons of structure total. If you're okay with a cramped feel, the practical lower limit is likely 600 tons structure + 400 tons payload. Bonus: You may want to have some large but extremely light inflatable parts of the structure ("balconies", "observation decks", "bouncy castles") which can only be used in good weather / low wind conditions; they would get deflated/reeled in if the winds are high. ]
[Question] [ Okay, I'm trying to make a planet that has at least part of its surface, or at least part of its underground, habitable for humans (breathable atmosphere at a suitable pressure, a suitable level of gravity and radiation, and a suitable temperature). The plants here are white in color. What kind of star(s) will it need to orbit, in order for white plants to evolve there? [Answer] ## A Red or Brown Dwarf Red and Brown dwarfs produce very little light in the visible spectrum meaning that plants would get most of thier energy from infrared light. Since visible light is not a major factor, plants don't really have a reason to specialize in the visible spectrum. That said, low exposure to visible light can also lead to a low resistance to it. Just like Earth life has a limited resistance to UV and greater, your world's sensitivity to short wavelength EM radiation may start in the visible spectrum. So plants, especially those that live in the brighter parts of the world, will evolve to reflect harmful RGB radiation making white a dominant color on your world. Also of note: Red and Brown Dwarfs are very long lived, stable stars. As a general rule of thumb, you don't really want a star bigger than a Type F Main Sequence star if you want to give life any chance of evolving into anything plant life. [Answer] As @L.Dutch pointed out in his answer, white is not a single wavelength, but a mixture of all the colours in the spectrum of visible light. However there is a way you can get white, or atleast, very pale plants. A plant, as pointed out, absorbs most of the light that falls on it (excluding the green part of the spectrum). However, if by chance, you managed to make the parent star extremely bright, then the plant would have to reflect off most of the sunlight, so as to prevent it from getting damaged. There is even a real life example of this. [Earth plants have been known to turn pale and die upon exposure to too much sunlight](https://aggie-horticulture.tamu.edu/ornamental/a-reference-guide-to-plant-care-handling-and-merchandising/light-temperature-and-humidity/#:%7E:text=Excessive%20light%20is%20as%20harmful,direct%20sunlight%20during%20summer%20months.). So, if you had a star that was extremely bright, then that would cause your evolving plants to be very pale, almost white and form an analogue to chlorophyll for energy harvesting. However there is a massive drawback to this. Really bright stars, especially above F-type spectral class stars, have a nasty reputation for releasing a b\*\*\*load of UV-rays. (Let's ignore UV flares from smaller stars like M-type and K-type stars for now, these are only rare events). So the planet's water would have been already have been disintegrated into hydrogen and oxygen and blown away before you even got simple bacterial life. I do not know for how bright would it have for your plants to be really pale, so as to reflect nearly all starlight that falls on it, but a certain-something tells me that you would need something like a A-type star for your plants to appear pale. Even if you managed to keep the water to the surface (thanks to ozone shenanigans blah-blah), you would face a big problem. Life is rather slow, like hella lot slow. It took nearly 3 billion-something for life to evolve from simple bacteria to walking bald apes who waste life making memes- no, we are getting off-topic. Anyways, the point is the same. Since our Sun is a long-lived star (As of 5th May 2023, it has about 7 billion years before it goes on steroids and expands into a red giant), life has a ton of time to spend to grow. But, boy, if you want white plants, then you have got only a trickle of time left (Ranging from a few million years to nearly just 1 billion years), because you need a bright star, and well, bright stars' lives aren't, well, very "bright". So you have got very little time for your white plants to quickly evolve. So, although you can get "white" plants, the possibility of getting them is very, very low. Your star will go supernova in just a few million years (Yes, a "supernova"), and life has got only that much time to quickly evolve into "white" plants. So, no white plants for you :( [Answer] None. White is not the color of a single wavelength. It's just the impression of all the perceived frequencies at the same time. A white plant would absorb very little light, which is what a plant needs to be a plant. [Answer] I'm interpreting your question to be equivalent to "what kind of light would cause white plants to evolve on a planet?" I make this distinction from that of the star because my understanding is that this is mostly a question of the atmosphere—most stars produce light across a very broad range of the electromagnetic spectrum, but atmospheres absorb pieces of the spectrum. Our atmosphere absorbs most light outside the visible spectrum and so (one can hypothesize that) plants on our planet have evolved to use light in the visible spectrum for photosynthesis. White plants would reflect light across the visible spectrum. This is a very small fraction of the total electromagnetic spectrum, so that shouldn't necessarily matter as long as there is enough usable light for photosynthesis outside of the visible spectrum. If the planet's atmosphere absorbs most visible light and lets pass a substantial amount of light outside the visible spectrum, then (one can hypothesize that) anything photosynthetic that were to evolve would be likely to use non-visible light for photosynthesis while reflecting visible light. This all requires hypothesizing that a photosynthetic mechanism could evolve that uses non-visible light; for what it's worth, I do not personally find this to be a very big leap for a science fiction world. Unfortunately, I don't have the expertise to tell you precisely what gases (or gas plus particulate) are needed to block visible light while letting pass other parts of the electromagnetic spectrum, but whatever the atmosphere was made of, it would almost certainly look black on account of its absorbing visible light. [Answer] A plant on earth converts CO2 and H20 + sunlight to food. The earths atmosphere blocks much of the energy that is outside of the visible spectrum (ozone < 300nm, H20 and C02 > 750 nm). Ozone doesn't block radiation < 200nm, ultraviolet. So a star that emits a lot of ultraviolet (bluer) that had plant life that evolved to use ultraviolet for photosynthesis could conceivably produce plants that are white to us. [Answer] It isn't the star, but biology. You should be able to achieve purely white plants with our sun. Chlorophyl is green, absorbing both blue and red while reflecting green, giving that color to plants. Yes, plants are throwing the most abundant light away for some reason - I have no idea why. Getting white color requires reflecting at least two wavelengths - check CIE color chart and drag any line that goes through the white spot and those are the two wavelengths you require. For example, your plants reflect blue/violet and yellow. They would want to get rid of blue and lower to limit UV damage (perhaps there is little to no ozone?); reflecting yellow for those white plants and green of our plants seems about the same (= I have no idea why, but ...) Note that while light reflected off plants looks white, anything illuminated by it will look weird. Say green stuff will look kind of grey, red stuff will look grey and similar. Perhaps that is desirable. [Answer] As mentioned in other answers and comments, greater sunlight intensity could result in plants developing pale colorations to protect themselves from excessive light. Brighter stars are an unlikely mechanism due to their short lifetimes, but a closer orbit will have the same effect, and a close binary would allow you to double the luminosity without shortening the lifespan of the stars. However it's achieved, it would need to be a pretty fine-tuned system to produce pale colored plants but not just overheat the planet beyond being capable of supporting complex life. One thing that helps: the stress of excessive sunlight will be stronger toward the equator. There might be more colorful life toward the poles, "bleached" varieties being able to spread closer to the equator. Or there might be a strong axial tilt, with the "bleached" varieties being able to grow further into the hot season, and winter life perhaps being more colorful. Also, yellow stars become more luminous as they age, swelling into red giants. A very old system might have a much brighter star, the plant life having had plenty of time to adapt to the increasing luminosity, and the light-colored plant life might actually be the only thing keeping the planet cool enough to support life. [Answer] Probably: **any**. It is a misconception that Earth plants are green. They come in red, green, and brown. It is really just a matter of what energy process or processes evolve in the plants. So it is all a matter of luck. [Answer] As so far everyone has mentioned, earth based plants are mostly green because there has been evolutionary pressure that lead to green being a dominant color. For earth this is mostly due to the spectrum of light (a lot of orange and red) but there are other colors in plants and these plants have survived the evolutionary pressure, so they are possible. What if there is another source of pressure that made these plants white? What if there is a reason that the other colors no longer exist? Maybe there was a plant-based disease that killed all non-white plants? Perhaps there was a mass extinction event that made all plant-eaters that saw color disappear and white plants are (or were) harder to see? Maybe white offered better camouflage for pollinators? Maybe there was a science experiment gone wrong by a (previous) intelligent inhabitant that made white the dominant plant color? Or the previous inhabitant had religious reasons to strongly prefer white plants and remove all others? ]
[Question] [ In my world, there are three distinct races with each their own country in a corner of the world, adjacent to one another and a central country. Simplified layout would be like the google chrome logo: [![enter image description here](https://i.stack.imgur.com/Z1380.png)](https://i.stack.imgur.com/Z1380.png) This central country would not be inhabited by a majority of any race, but rather a mix of all three races. It would be self-governing, separate from any of the race-specific countries. As for the other countries, they would be almost constantly at each others throat on the borders due to the aggressiveness of one of the races. Magic exists in this world, but is mostly contact (hands on) object manipulation and real-time directional clairvoyance (sensing what happens around you or at a distance). No destructive spells or ranged attacks (by magic at least, bows etc. still exist). It is not very common as a reasonably strong affinity for it is needed genetically (everyone has the affinity, in varying levels), and even then a large amount of training is necessary to use it effectively. Time/technology setting would be similar to around year 0 of the Gregorian calendar. One of my races would be proud and slightly selfish, but otherwise neutral/pacifist. They commonly have a moderate affinity for magic, mostly towards object manipulation. Another one would be fairly aggressive and lawless, aimed towards anarchy and expansion of their territory. Commonly low affinity for magic, but large physical strength and size. The last one would be smart and sophisticated, but completely pacifistic. They have a strong affinity for magic, especially the clairvoyance kind. How could a balance between these races in a central country work, without constant internal feuding? Why would any members of any of the races chose to live there, rather than in their own country? How would they prevent any of the races trying to take over completely, adding (part of) the central country to their own territory? It being a democracy for example would already help, but it doesn't completely cover all questions. Bonus question: The reason this centralised country exists in the first place is a secret revealed much later on. How would the races themselves explain or justify the existence of this central country in the meantime? I haven't decided on any geographical details yet, so feel free to use terrain layout in your answer if necessary/helpful. Please let me know if clarification is needed anywhere, or anything needs to be more specific. [Answer] The central nation is a kingmaker in the conflict between the nations. It is not as powerful, but it can deal enough damage to ensure any country that attacks would fall to its rivals. Perhaps magic is stronger in the location, there is a dragon / council of powerful mages defending the place, or they've got a single use WMD. Sure, two nations could work together to take them out, but that would require cooperation, something your three nations won't do. And your middle nation engages in espionage to keep it that way. [Answer] The central territory can be hosting an important religious item, which is worshipped by all the 3 nations. As such whoever tries to take over the central region, will 1. openly violate the sacrality of the territory 2. be sure to face the combined reaction of the 2 others, being in evident inferiority The above is enough to ensure an equilibrium in that region. [Answer] How do Switzerland and Belgium exist as stable countries? The answer is a mixture of: (a) they have their own identity separate from their linguistic community identities (b) geographic governmental subdivisions that break roughly along linguistic lines (c) in Belgium, non-geographic linguistic-based governments co-exist with geographical governments (d) all governmental subdivisions have very high levels of autonomy (which prevents tensions from rising too high) (e) strong, democratic institutions that maintain a sense of overall fairness (f) In Belgium, which spends long periods without a federal government (due to inter-community tensions over fiscal matters) the high levels of autonomy and rules that allow tax and spending policy to continue without interruption (entirely unlike the US federal debt limit). (g) Invading Switzerland is a dumb move, a bit like invading Afghanistan; security treaties came into existence to guarantee the independence of Belgium as part of the post-Napoleonic european settlement. [Answer] It’s a fourth, more liberal country. It governs itself. It has its own borders. Clearly it values immigration from its neighbours while they don’t seem to. It looks a lot like this place is a much more liberal ‘live and let live’ place to be than the more nationalistic triad that surrounds it. Bill it as such. People who want a multicultural society will go there. People who don’t will stay home. It can get support and/or angry vitriol from each of its neighbours foreign offices depending on the ebb and flow of politics, and as long as it’s a reasonably strong country in its own right (or has the right alliances/trade deals/various reasons for not getting crushed) it will remain a sovereign place for the more open-minded citizens of all three countries to meet and live together. Until Politics happens, of course. Then the knives come out... [Answer] "How could a balance between these races in a central country work, without constant internal feuding?" ... "How would they prevent any of the races trying to take over completely, adding (part of) the central country to their own territory?" Well, only one race is aggressive - let's call them "orcs". If they attack the pacifistic clairvoyants ("elves"), these will just make sure never to be there when the "orc" attack and move in where the "orcs" have left. The "elves" may also use object manipulation to harass the "orcs" - suddenly, there are walls all around them, and their possessions (including clothes) tend to disappear at night. Eventually they give up and choose to attack the proud, neural race ("dwarves"). These are well able to defend themselves, and meanwhile, the "elves" take possession of "orc" territories through non-violent means similar to how they defended themselves. Finally, the "orcs" throw up their hands in disgust and stick to their own territories. The same pattern is reflected at the local or even personal level. "Why would any members of any of the races chose to live there, rather than in their own country?" Maybe they want more variety than they get at home, or they are rebels against tradition and authority. Or they might be poor people (or descendants thereof) looking for opportunity in a place where their low birth doesn't mean anything. "Bonus question: The reason this centralised country exists in the first place is a secret revealed much later on. How would the races themselves explain or justify the existence of this central country in the meantime?" I take this to mean that something prevents the three countries from attacking the central country, and they rationalize their lack of ambition in some way or other. Again, only the "orcs" sound like they are really interested in conquest. It may be that they simply fear that the two other peripheral countries will move into their territory while they are away on conquest. Or there are geographical reasons why conquest may seem not worth the hassle: inaccessability due to e.g. mountains or no obvious values in the shape of resources, good farmland, or rich trade. Conversely, the central country may have originated as a neutral trade station. Perhaps sailing around is difficult or dangerous, e.g. because of reefs or aquatic monsters? Perhaps navigable rivers from a central plateau make travel easy - except from the last stretch, where goods or ships have to be lifted onto and down from the plateau, e.g. through a series of sluices? Whatever the reason, this country succeeds in maintaining its neutrality because everybody benefits from the trade. The plateau may even hold certain unique trade goods, but it is too hard to conquer. [Answer] The first question is why was this fourth country settled and/or created in the first place? If this was a place where the three countries meet geographically, then this fourth country could have started as border outposts and lookout towers close together in order to watch their borders. Perhaps after a particular part in the land's history it was decided that this would be a neutral ground for whatever reasons that the races decide officially. That alone, would not make it a more homogenized country. But eventually people will either be forced to coexist, or willingly consort with the other races for their own reasons. From there, it will only be a matter of time before the mixing creates a fourth distinct cultural identity, and a fourth country is truly born. As for the bonus question: Officially, this fourth country exists as a matter of mutual agreement and benefits. After all, a neutral country is a good place to hold negotiations between countries, and the knowledge that comes from all three races putting their heads together has value. It is also a good home for a noble that needs to be exiled, but remain alive and close enough to watch. Unofficially, the secret is why this agreement was ever made in the first place. It is just that this secret reason was forgotten. One theory was that all three races watch over this area because something happened that forced them to work together to handle it. Once handled the alliance ended, and the official agreements were made to ensure that it remained handled. [Answer] > > The reason this centralised country exists in the first place is a secret revealed much later on. How would the races themselves explain or justify the existence of this central country in the meantime? > > > I take this to imply that the reason this communal country exists is a secret, and should be amenable to a Big Reveal. One option would be that the situation is artificial. For example, perhaps your three species are the artificial organisms that were sent to tereform a planet. The central area is the original landing zone/operating area, an aura of peacefulness exudes from it (maybe they've expanded past the natural operating zone because the colonists never showed up or whatever). The inhabitants of the planet just think of this as a natural trade and diplomacy hub. This is a scifi-centric setup of course, but it could easily be reskinned for fantasy, just replace bio-engineers with wizards of course! [Answer] The land is barren and worthless, vast deserts with few oases and little in the way of valuable goods. None of the surrounding countries want it; it's not worth the trouble to conquer, and even if you do then you end up with an over-extended border in contact with both rivals and no return on that investment. Inevitably anyone taking it ends up withdrawing eventually, and giving it up as a lost cause whereupon it collapses into anarchy again. The locals are too busy trying to survive to fight each other. They don't care about what species you are, just whether you have anything to trade or are coming to attack them. No-one chooses to live there. Instead a penalty for mid-level crimes is banishment to the desert either itself or in combination with other penalties. Depending on the severity of your crime when banished, you are given anything from a set of clothes and a waterskin to nothing at all and kicked out into the barrens. [Answer] Apologies in advance for the fact that this answer wanders into some really ugly bits of Terran history. Borders are naturally porous. Show me a border almost anywhere, and I'll be able to find a bunch of people who've settled on the 'wrong' side of it. People wander, they fall in love, they seek employment. They come out on the wrong side of a civil war; they join religious or philosophical movements that one or another leader bans; they flee localized famines; they seek seasonal work in places where the seasons are different; they set out to walk around the globe for no good reason; the border moves across you as a result of a stupid war or a monarch desperate for cash. The fact that your races *actually* differ greatly in ability means that each race's special skills are much more valuable among the others than they are among their own. So... the first question to consider is what makes the racial nations racial nations in the first place (which may differ from nation to nation, of course). Are they ethnic supremacists? Does some magic force cause people to gradually shift towards the majority race? Are they ethnic separatists, for whom any war of expansion is necessarily a prelude to some form of genocide? Are they multiethnic states where the nobility just happen to be of one race? What is the role of other races in the three racial nations? The cultural infrastructure necessary to enforce ethnic supremacy and separatism winds up *also* oppressing members of the favoured race(s), even if they don't have it *quite* as bad as the unfavoured races do. Consider the Interahamwe treatment of moderate Hutus, the Third Reich's treatment of Aryans who sided with the occupied countries, the Khmer Rouge treatment of Khmer. More recently, neo-fascists keep killing leftist Whites, and I personally have met people who've been beaten up for being the wrong race because they came from a village 30 kilometers away. Other questions worth burrowing into to help shape this: Would anarchists even have a single nation? It seems like if they were actually anarchists they'd schism just as much as the debating society anarchists we currently know do, and for most of them "steal the neighbour's cows while he's off raiding the pacifists" is a much easier task than "march twenty days to the border so we can steal cows from the pacifists". (Which also provides a pretty good motive for anarchists to go live in the central nation - maybe they don't actually see anything WRONG with stealing cows, but it's less WORK to live in a country where you can't steal the neighbour's cows BUT you also don't have to worry about the neighbour stealing YOURS.) How do the pacifists maintain independence? Vastly different habitat requirements? A complicated system of rationalizations such that they consider releasing rabid smeerps in an enemy warband's camp nonviolent? If it's Complicated Philosophical Rationalizations, it's not hard to imagine some pacifists deciding that it's slightly less immoral to kill someone directly than to make them die slowly through smeerp-rabies, so they'd rather live among people who are slightly more honest about their violence. [Answer] The example I put forward is Canada. We have "the French" and "the English" and "the Natives." And many other people who have joined in the fray, and who are learning the game. The primary way we get along is to have certain methods of relieving the pressure. These means are sometimes officially illegal but in practice they are tolerated. To some extent. And sometimes they are officially legal, but discouraged from happening very often. Example: As I type this, there is a protest being carried out by Natives over much of the country. They are opposed to the construction of a pipeline. This is being joined in by sympathetic persons from non-Native communities. They are blocking train tracks. The result has been significant disruption of both passenger and freight traffic over large parts of the country. This is officially very illegal. But, it being a political protest, it is tolerated to some extent. The federal and provincial transportation ministers have agreed to meet with their leaders. The result is, much of the energy and excitement and anger surrounding relations between the Natives and everybody else is drawn to these protests. It gets used up. And then a new acceptable compromise is reached. Hopefully it can be resolved without bloodshed, and without too lengthy a disruption of train travel. Example: Periodically separatist movements gain some traction. This happens at least relating to Quebec, and to the Prairie provinces. And to an extent for the Native regions. They join, make political groups, give statements to the press, hold rallies, and such. Sometimes they go so far as to get some kind of referendum together. The usual result is that politicians join together to look at the situation. They decide that they are Men of Principle and that the Principle they want to be most associated with is COMPROMISE. And we get a new agreement on a new acceptable compromise. We get such things as the "not withstanding" clause in the constitution that lets governments do things for the stated purpose of "national unity" even if they violate the constitution. And all they have to do is renew it every few years and say "not withstanding" and then go on. There are lots of other examples. For example, there is a national pension plan. But individual provinces can opt out and have their own plan. There is supposedly free trade between the provinces, with no customs or border patrol. But provinces are free to insist on things like "domestic content" and quotas on imports from other provinces and provincial sales tax being paid on imported items and so on. I recall a story about an enterprising young lad who noticed that the sales tax on beer in Newfoundland was much higher than in neighboring Quebec. So he arranged to bring a series of transport trucks full of cases of beer to just on the Quebec side of the border, and sell out the back of the truck. This was something like a 25% difference. So people were bringing their vans and pickup trucks and buying dozens of cases and taking them home. He got shut down pretty quick. The result is, people who ordinarily would have very much difficulty living together can manage it. There are disruptions and hiccups and sometimes drastic bad things. For example, [The October Crisis](https://en.wikipedia.org/wiki/October_Crisis) involved a group of Quebec separatists who got way over on the terrorist side of things. And we found out what The War Measures Act looks like in action. But most of the time we deal with it by making jokes about each other's accents. And jokes about "how can you eat that?" And jokes about hockey. And jokes about how glad we are not to be Americans. [Answer] The central state is a technocracy or a magocracy. It is populated by enlightened elites who see the folly of the ways of the eternal conflict of the external states. Immigration to the central country is strictly prohibited by superior technology or magic. Invasion is unthinkable due to military superiority. The central country actively seeks and abducts citizens of the other countries that show potential in engineering, research, or magic. [Answer] **The groups in the central country have a common cultural ideology that unites them and distinguishes them from the other three** Multicultural nations generally work by having a common cultural ideology anyone can be a part of regardless of social class or ethnic group. Having a common group identity that anyone can be a part of encourages social cohesion and prevents “us versus them” tribalism reminiscent of *The Sneetches*. That’s how the Achaemenid Persian Empire did it, that’s how the Romans did it ([Romanization](https://en.wikipedia.org/wiki/Romanization_(cultural))), that’s how ancient China did it (and to some degree still does today), that’s how the Soviet Union did it, that's how India kind of does it ever since they fought for independence from the British Raj, and that’s how many Western nations do it today (most notably but not restricted to the U.S.). Exactly how well these countries live up to the ideals set is something that literal volumes have been written over, but in bare essentials that's the idea of how it's supposed to work. It doesn't have to replace the parent culture, but has to at least complement it (as an example, look at immigrant communities in many nations across the world today). What this would look like in your case is while members of these races across the four countries might look like they belong to the same culture, *they* wouldn't consider themselves as such. Lets say these are elves, orcs, and humans for sake of example, since that's the general analogy previous answers have gone with. Elves in the central country would consider themselves to be a separate people from elves in the elven country, and there would likely be cultural differences between them. The elves of the central country would consider themselves more culturally similar to orcs and humans from the central country than to the other elves (and likely vice versa), and their subculture within the broader central country culture would likely be a mixture between elven traditions from their own background, cultural ideas they picked up from diffusion with the orcs and humans, stuff they came up with on their own after immigrating from elf land, and the general central culture background ideals that hold the country together. If these groups cannot interbreed or rarely do so as your question seems to suggest, cultural barriers would remain up longer compared to all-human countries where intermarriage is possible. Switzerland, as mentioned in another answer, is a good example of this. Despite having people of Italian, French, and German descent, people in Switzerland don't consider themselves Italian, French, or German. They consider themselves Swiss. The people in the central country, at least as a majority, have to *want* to be together based on cultural unity to some degree for the country to work. Iraq, Rwanda, and many other countries in Africa and the Middle East shows what happens when this doesn't occur. In these cases various groups that didn't have a common cultural identity were divided up together into a single country by European imperialism (or just arbitrarily assigned one in the case of Rwanda) and the various groups butted heads. This has even been mentioned as one downside to the overthrow of Saddam Hussein when talking about the long-term stability of Iraq, the Iraqi military was creating a common Iraqi identity that was keeping the various factions together and allowing the country to function to some degree. A good example of this in fiction is the United Republic of Nations in the *Avatar* series. Despite being descended from Fire Nation colonies set up in Earth Kingdom territory, the United Republic of Nations are clearly a distinct cultural entity from either country and this only becomes more emphasized as time passes in-series. > > When the Fire Nation tried to give the colonies back to the Earth Kingdom after the Hundred Year War, the colonies rioted because a significant portion of the population had mixed ancestry and they were threatened with deportation, and the population did not see themselves as culturally identical as the Earth Kingdom. This is even more emphasized in *The Legend of Korra*, where the United Nation of Republics is a technologically advanced metropolis with its own methods of government different from the monarchial Fire Nation and Earth Kingdom, its own unique styles of the various bending arts, and even differences in fashion, whereas the Earth Kingdom is largely technologically backwards and impoverished and culturally very different (though mostly unchanged from *The Last Airbender*-era due to government mismanagement with the exception of Zaofu). What happened to the Fire Nation is never shown. > > > Religion can be another way to achieve this (I mean, religion is basically a form of ideology anyway). The Abbasid Caliphate ruled over a lot of different cultural groups, including Arabs, Egyptians, Persians, Seljuk Turks, and various Christian and Jewish groups, among others. One major factor holding the caliphate together was the fact that most of them practiced a common religion, Islam, and the government put in policies to try to convert people who weren’t Muslim through incentive of tax writeoffs and other means. [Answer] Sounds a little bit like Antarctica. A lot of countries have laid claim to various parts of the continent, but IIRC, following an international treaty they have all put the claims “on ice” and agreed to only use Antarctica for scientific research purposes. So you have countries like Argentina, South Africa and Australia which would be equivalent to your outer coloured areas and the southern ocean would be the white bit. [Answer] In the case of Spain, centuries of forced “unity” have weakened the strength/size of the separatist groups. Even the basques are assimilating to the point that most of the young can’t speak the language. ]
[Question] [ I'm working on a post-apocalyptic world for a game and the more I think about it the more unsure I get about the technological development of the setting being believable. So I'm asking how likely a certain level of technological regression would be given the following assumptions: In a world that experiences a long lasting dramatic global cooling (a series of impact winters caused by a shower of asteroids that impact the earth over time for example, or maybe a volcanic winter?) for more than a century, reducing humanity to a population of maybe 2 million globally. How much technological regression would be plausible in this case? Assume that most technology that is in use by then has become complex enough that simply copying them cannot be done (requiring advanced electronic manufacturing and such). * Would it be plausible if the knowledge of electricity is reduced so that it becomes impractical? * Would it be plausible if the knowledge of chemistry was lost to such a degree that only the most useful and easiest to do formulas would be remembered? * Would it be plausible if knowledge of manufacturing strategies were reduced to such a degree that humans would be stuck with artisanal production for a long time after? Would it also be plausible if recovery was slow, in the level of several centuries, after such an apocalyse? In such an apocalypse, global trade networks would collapse quickly I would assume (especially if there are armed conflicts between groups of survivors for the little fertile land that is still there during the long winter) I would assume and a lot of technology would be impractical for a long time in the future as requried materials would be very hard to get and might even be hard to salvage from the ruins of the old world in sufficient quantities. Though some of it would be possible I'm sure. Power sources would be limited, wind power might still be doable in the small communities that would survive but would it have enough practical uses to preserve for such a community? I would assume that most fuels would be impractical for such a community, with easily accessible oil and coal deposits already being depleted. So I guess easy portable electric power would be out of the question. Likewise, I also assume that the vast majority of people will be forced to do tasks that are required for basic survival, whether they work in Agriculture or other basic resource gathering operations. Furthermore I would guess precision machining would not be doable without access to already complex machinery, limiting how complex any mechanical machines would be. But I'm unsure how fast these capabilities would be to reacquire. Finally, even if the old society had mostly phased out text books in favor of digital media would the surviving text books still around be enough to rapidly have society regain the lost knowledge to a level where they can make practical use of it? [Answer] There are minimum population densities that you need to maintain in order to have a given degree of specialisation and division of labour. If the population is broken down into single families trying to scrape a living in hostile conditions then they don't have the time to maintain the equipment they have let alone manufacture new so in terms of material culture they'll revert. Over the short-term, for maybe three generations, there will still be a practical knowledge of a lot of technology that there isn't the labour to maintain in physical equipment. After those skills die out there may still be printed records available for some time to come, these will largely form a basis for experimentation rather than a ground up how to guide in most cases because they're too technical for someone without a grounding in the basic operations. In short if population densities remain extremely low for extended periods, like two-to-three hundred years you could theoretically push people back to stone age farming. In reality I think there are two barriers to that: 1. It would take a severe drop in average fertility to keep people down in numbers and population density long enough for all the people with skills and knowledge to die out. 2. We use too much metal in the modern world; after most of the population is dead a modern city becomes a huge mine for refined metals. Even if you have to break [rebar](https://en.wikipedia.org/wiki/Rebar) out of [K-rails](https://en.wikipedia.org/wiki/Jersey_barrier) with rocks it's still far easier that mining and smelting ore. Given the huge volumes of metal in modern buildings I'd expect something like the late iron age to be as far back as you could go near existing settlements, even reasonably small ones. [Answer] ***Would it be plausible if the knowledge of electricity is reduced so that it becomes impractical?*** Not really. Electricity, it's uses, and it's conveniences are widely known and taught. Many, many toy stores have electricity learning kits. Every science museum in the world has displays and hand-on learning tools. Most schools in the world teach about it. You may not recall the details, but a trip through your memory will lead you back to that museum or that toy store, and the raw materials and techniques to re-learn. ***Would it be plausible if the knowledge of chemistry was lost to such a degree that only the most useful and easiest to do formulas would be remembered?*** Chemistry would certainly not vanish. Just knowing the fact that there *are* formulas (and elements) skips thousands of years of slack-jawed guessing. My dining room has a *place mat* with the periodic table. One of my teenage kids has a T-shirt with the periodic table printed on it, and (out of earshot of her peers) will sullenly admit to fully understanding most common chemical concepts. Those toy stores and museums have chemistry learning tools, too. ***Would it be plausible if knowledge of manufacturing strategies were reduced to such a degree that humans would be stuck with artisanal production for a long time after?*** Well, that doesn't kick us back very far at all. Modern industrial mass production is only a tiddle over 100 years old, and many current methods (CNC, robot-assist) are barely one generation old. There's nothing magic about them - most are simply incremental improvements that can be quickly re-learned when required. [Answer] There is no amount of physical destruction (books, tech, etc) that will solve the problem because an absolute boatload of knowledge is in people's heads. 99%1 of today's technology was created in the last 150 years. This strongly suggests that, if all the books and toys were taken away, it would be recreated in ***no more than*** 150 years and probably a whole lot less. In my opinion, believably within a single person's lifetime. *Not to be too sarcastic, but necessity breeds (re)invention, and what's more necessary than snapchat? Am I right, or am I right?* üòÄ That means you need to get rid of more than the books and the toys (because any toy left behind is a massive clue. Reverse engineering isn't as hard as people think.), you need to get rid of *people* or force people to not use what they know. **Option A:** You get rid of the *right* people. This is (for example) a highly selective virus that only infects people above a certain IQ, or that have a specific knowledge base, etc. But, this is the most unbelievable scenario I can think of. **Option B:** You get rid of everyone above an age that could possibly replicate technology. This is much more than the people who actually *know* how to do something, you need to get rid of people who *remember* that something can be done. Remembering that you can use a rounded-piece-of-glass reinvents the field of optics a whole lot quicker than not knowing about glass at all. Killing everyone above 13 *might* do it. Killing everyone above 6 would do it — but you just put the entire population at unbelievable risk because 6-year-olds have a bit of trouble taking care of themselves. **Option C:** Something (usually war) gets in the way of re-development. This means the knowledge is there and even appears in pockets, but the full re-development is nearly impossible due to an external force that prohibits that development. The chaos of war is the only thing I can think of that would do that. But this doesn't solve your problem. Today's knowledge is still in people's heads. Give the right dude in the back woods someplace with reasonable resources (like nearby hardware/feed stores that have animal antibiotics and fertilizer), most of modern chemistry could be recreated in a few years. Most of all modern tech could be recreated very quickly as peace (and the communication that comes with it) is re-established, and warlords would begin to realize the value of their ~~wizards~~scientists very quickly. Therefore, I don't see this option as helpful to you. **Option D:**—A virus or magic death ray that wipes out memories. Even if you had all the books and toys, if you can't remember how to read, how to speak, etc., then you really are pushed back to the stone age and the presence of all the knowledge and technology around you can't help you. Option D is obvioiusly my favorite choice. We get a lot of people on this site who ask along the lines of "my post-apocalypse society has been pushed back to the stone age and here's my question?" Except that there's rarely a serious explanation of *how* they got pushed back. The people who ask that question don't understand the considerable *depth* of understanding that comes from just using the technology of today. Really, if you were a 10-year-old who grew up with a yard with a sprinkling system, how hard would it be to realize irrigation would help you grow crops? **Therefore, from my point of view (and to answer your question), it's all or nothing. You either push people back a few decades, or you push them all the way back to the stone age. There's nothing in between.** --- 1 *Metaphorically. I don't know the actual percentage and don't believe it matters.* [Answer] ### We can do a lot, with a few people, if we WANT to If you haven't done so already, read at least the first novel of [the 1632 series](https://en.wikipedia.org/wiki/1632_(novel)). Basically, 3,000 people from a small town in West Virginia in 2000 get transplanted to 1632 Germany. The key points I see relevant to this discussion are: 1. **Knowledge** is the most important thing. 2. Even if computers become useless (they won't, by and large, last 100 years, and producing new computers won't be easy), **books** will last a long time. While we rely on the internet for "everything", there is plenty to be found in printed books. Printing more books to distribute knowledge doesn't require 21st century technology or mass production from factories in China. 3. If the surviving people **want** to accomplish a lot, they **will**. That's not to say it will be easy. If all major factories, large electricity generation plants, etc. are destroyed and people have to live off the residue of modern civilization for 100 years, they won't immediately bounce back to the iPhone era. But **knowing** what is possible, they can easily stay at least at mid-19th century level and likely surpass that quite easily. Some things will be tough. Precision machinery actually may be one of the easier parts. One good machine shop that survives (I think there were 2 in 1632) can bootstrap a lot of other things. On the other hand, integrated circuits will take a long time - you can't build a chip fab out of sticks & stones. But even without a chip fab, and with most of the pre-apocalypse computers gone (and no internet), it won't take long to restart production of some basic computer technology using relays, vacuum tubes and transistors. Unlike the first time around, they won't need to figure what to do or how to do it - just get together enough people who want to do it. As far as electric power - which is arguably **THE** key to modern civilization as we know it, solar cells & nuclear power are not gonna' happen. But small-scale hydro and steam (using **any** available fuel) is simple enough. [Answer] # Information priorities become different The priority is survival. Right now, to survive you need a job, the ability to make money with which you buy food and housing. Post apocalypse you need the ability to find food and shelter, gold is quite low in calories no matter how much of it you have. That's the extreme example of course. While knowledge may not be lost as such, it can become irrelevant. Your hard earned C++ skills are wasted in a world without electricity. Your knowledge of how to build a large scale power plant is pointless when a 200W [PV](https://en.wikipedia.org/wiki/Photovoltaics) system covers all your needs. A lot of what drives science and industry is population pressure, the need to know how to do more than grow potatoes and milk a goat. Without the pressures to need to have the knowledge, it becomes irrelevant. Consider a specialist in large scale international economics, what use is he now? Why would he bother passing that knowledge on? It could be 20 generations before that information is needed again. **Would you rather be working a 60 hour week in an office or weed the potatoes in the morning then spend the rest of the day playing shesh besh with your friends?** The pressures of society drive technology and its uses, while it would take some time for society to drop down to pre-industrial revolution knowledge, it would only take a reduction in numbers and need to reduce to pre-industrial revolution requirements. You don't need to farm when you can hunt and gather, population pressures require farming. Increased population pressures require intensive farming and on from there back into the industrial revolution. If all your needs are covered by wild plants and hunting, **it's not so much that technology is lost, it merely becomes different and much of what we now consider important loses any value.** [Answer] Long winters are great for technology regression because burning books is a great way to keep from freezing to death. In warmer, more comfortable apocalypse scenarios, a few carefully selected and plastic wrapped text books is all it takes to restore any survivors to early 19th century technology levels. The only challenge with apocalyptic winters is that the very technology which you are taking from the survivors in return for one night's heat is the only thing that can save them from freezing the next night. Multi-year winters can be survived with artificial grow lights and electric heaters. Without those tools, starvation is likely to prune your survivors down to a story-killing zero. So you as the world builder, need to walk a tight-rope, providing enough hardship to eliminate the textbooks and others sources of knowledge, while leaving a believable margin for survive-ability. This will be challenging, but not necessarily impossible. [Answer] This sort of argument is when I like to bring up my personal theory on Noahs Ark and the literal thousands of sunken cities around the world. Not saying that all of the Noah's Ark story is true or not, but if you had to restart society with just you and your family, even a handful of other random strangers, would you start diving right back into advanced engineer techniques? or would you start off with grass huts and leather tents? Sure you may have a lot of knowledge on how to rebuild common technologies (like a wheel barrow, a windmill, or a battery), but the survivors acquired that knowledge through years of learning and exposure. Their children and grandchildren will likely be taught much of the basics, but be too busy trying to survive to come close to the same level of knowledge. This is especially applicable when the population is too low to form a secure community. Teaching would likely be left up to the elderly who would gradually become fewer and fewer as people will begin to die younger from generation to generation with the loss of vaccines and medical technology until it plateaus. Depending on the type of disaster, the amount of civilization left over basically determines the cap on how much technology they can recover, and that's not to mention the sharp drop in literacy. Who cares if your survivors built a colony inside a massive library if only a handful can read? They don't have time to spend hours learning calculus or physics, they need to scavenge for supplies and farm for food. Over all, I just think that a lot of the optimism around recovering technology completely disregards the entire issue of basic survival. [Answer] Maintaining a high-tech economy requires a lot of people. I like to think I'm a smart guy. I develop software for a living. So suppose I tried to redevelop technology from scratch. I have a basic understanding of how computers work. Could I "re-invent" the computer? Not likely. I know computer chips are made from silicon and germanium. We get silicon from sand. Cool. How do you turn sand into usable silicon? I haven't the vaguest idea. Where do we get germanium? What does raw germanium in nature look like? I have no idea. Okay, skip to something simpler: We'll need wires. How do you make wire? I don't know. Most wire is made from copper. So we'll have to mine copper ore. What does copper ore look like, and where do you find it? I haven't a clue. I suspect most intelligent people would be in the same boat that I am. We know a lot about some narrow field. But making that work requires lots of other moving parts, and we know little or nothing about most of them. And not to be insulting, but most human beings aren't smart enough to build advanced technology. Even with detailed instructions, many couldn't manage it. I've worked in tech support, trust me on this. If just the right books survived, I presume smart people could figure it out. I suppose that if I knew the apocalypse was coming and I was given access to any experts I needed, I could put together books telling someone how to build various technology, step by step, from zero. Here's where to look for copper ore. Here's what it looks like. Here's how to dig it out and refine it. Here's how to make it into wire. Here's how to make insulation. Etc. up to here's how to assemble all these parts to make a power plant. I'm sure there are books out there on all the pieces of this. But someone trying to rebuild would have to find all those books and read them and understand them and pull it all together. I think that would be very hard. In a post-apocalyptic world with a greatly reduced population, I think there would be many communities with someone who is an expert electrician ... but who has no idea where to get wire and switches. Another community might have a great miner ... but he has no idea how to refine the metals once mined. Etc. There would be lots of people who know how to do step 7 in some task, but there's no one around who knows how to do step 6 or step 8. Or someone might know how to do a step if only he had the right tools, which he doesn't, because he doesn't know how to make the tools. [Answer] Based on JBH's answer: if things aren't absolutely extinction-level terrible, then it seems to me that the human race can be expected to recover into self-sustaining "local industry" - farming and ranching, printing, masonry, gunpowder, basically 1600 +/- 200 years. Toss in some surviving knowledges. Consider Amish and Mennonite settlements. I think the BEST outlook would have smelting and railroads. We'd skip over the telegraph and go straight back to land-line-based telephony. I'm less optimistic about factories, though I'm not sure. Consider the future-renaissance village: it looks like the stereotypical colonial New England village... but they've also got calculus and arc-lights, and they understand about germs and the sources of disease, they know most of the periodic table, and they can do a lot with chemistry. They have the Jacquard loom, and take full advantage of water wheels and windmills. They might have mechanical adding machines (or they'll just use the abacus). They'll have the "optical telegraph" (heliograph). If you're edging a bit more into fantasy, they could have functioning Babbage Difference Engines and Analytical Engines. [Answer] My opinion would be the regression most likely would come in a form of oppression. Our fondest historical references to innovation in academia and technology come from moments of oppression where culture and religious government oppressed advancement out of fear and control. We may see this after a worldwide apocalypse. People believing that technology destroyed the world push against development. Person to person, re-emerging political governing bodies and spiritual organizations all would affect the rate of advancement. But this would still be temporary as pockets of isolated areas may not come to that conclusion, see technology as a means for gaining an upper hand on a neighbor or simply be havens of optimistic new inventors who have incredible access to already developed technology. We all have looked at a toy as a child and desired to break it to understand how it worked. That fire would reignite once the new world passed from a dark survival period to re-emerging societies. ]
[Question] [ How dense would an atmosphere (that's presumably non-toxic) need to be in order for a human being (without wings, artificial or otherwise) to achieve unassisted flight (without killing said person from pressure)? Or is atmospheric density unrelated to this? [Answer] We call this "swimming" and you'd need an atmospheric density roughly that of water. The pressure needed to get a gas at that density has serious physiological effects, so just compressing the right gas mixture (one selected so as to not produce poisonous partial pressures of any of its components) wouldn't work. It is certainly possible to put enough oxygen into some liquids that there is the potential of breathing "under water," but I'm not sure that such breathing is actually practical. If you allow limited breathing equipment, it's easy. [Answer] The answer to this is as complicated as the equations of flight. Basically there is no single answer, it depends upon many variables. I wrote those detailed answers on the topic of flight for previous questions. So please read these if you are interested in the details: * [A world with 1/3rd gravity but 1/2 atmospheric pressure. Would it be easier to fly?](https://worldbuilding.stackexchange.com/questions/18665/a-world-with-1-3rd-gravity-but-1-2-atmospheric-pressure-would-it-be-easier-to-f/18668#18668) * [Air transport breaks down](https://worldbuilding.stackexchange.com/questions/14161/air-transport-breaks-down/14166#14166) * [What would humans wings need to be like to fly?](https://worldbuilding.stackexchange.com/questions/39736/what-would-humans-wings-need-to-be-like-to-fly/39739#39739) ## TL,DR; If by "without wings, artificial or otherwise" you meant no bits of vehicle, then the conditions of lunar gravity with Earthly atmospheric density would permit a person with normal musculature to fly wearing only a simple suit with "wing fabric" stretching from the arms to the body. To accomplish the same feat on a planet with a full 1 g of pull would atmospheric density of greater than 6x that of Earth. To accomplish the same feat *without* the wing suit, I don't know. Human arms are not designed to generate lift and most of the arm won't generate lift at all. I am only certain that humans could shape the hand correctly for lift generation and that is not much lifting area. At a guess, you might require another >10x increase in atmospheric density to fly. My best guess is it would take >60x Earth sea level normal atmospheric density to do this. If Venus were livable, then you could probably fly there with just your arms & hands. Quick note: you are correct about the relevant parameter being atmospheric density. You can manipulate the density while keeping the pressure the same by using heavy inert gases (aka Xenon) as the mixing gas rather than Nitrogen. But this can only "purchase" 4x the atmospheric density. You'll still need to increase the number of molecules in atmosphere by >15x that of Earth sea level atmosphere. ## Details I was going to break down the details of this solution, but realized that the above references include all the math you need to figure this stuff out. and I'm feeling lazy today :) Anyone looking for the details of how to figure this out, please read the three above reference answers. [Answer] In order to fly one has to contrast the gravity force. This can be achieved in multiple way: * Bernoulli lift force: by having wings and a suitable motion, the resulting force can contrast gravity and enable flight. You have ruled this out. * Reaction lift force: by using Newton's third law of dynamics, one can generate enough force to contrast gravity. This is the principle used by rockets. * Drag force: in a fluid moving at adequate velocity, the drag force can contrast gravity (it happens if you are caught in a tornado) * Buoyancy force: that's what happens when we swim. To have this, the density of the fluid has to be bigger than the average density of the body. Gases are 3 orders of magnitude less dense than solids/liquids. There is no way a gas alone can make a human fly by buoyancy. And tornadoes are not practical for intentional flight. [Answer] To achieve [Neutral buoyancy](https://en.wikipedia.org/wiki/Neutral_buoyancy), atmospheric density has to be just over 1000 kg/m3. That's a lot. For comparison, normal atmospheric density is just 1.225 kg/m3, so this is over 800 more dense, and atmospheric pressure (assuming composition is constant) has to be over 800 atmospheres. That's the level of pressure at ocean depths over 8000 m. Not healthy at all. However, if the nitrogen is eliminated from the breathing mix, and oxygen level is decreased to a trace level that would be tolerable, humans could survive in this environment, at least for a while. I suggest replacing most of the atmospheric content with Neon. As an inert gas, it won't affect body chemistry. Unlike heavier elements like Argon, Neon is thought to not cause narcotic effect, and its molecular weight (20.18) is 5 times higher than Helium, which means we would need 5 times less pressure for the same density. So, neutral buoyancy neox atmosphere will need to have pressure about 1100 atmospheres (higher than air because neon is lighter). While living in these extreme conditions is theoretically possible, it was never studied, and some heath problems like [High-pressure nervous syndrome](https://en.wikipedia.org/wiki/High-pressure_nervous_syndrome) are guaranteed to occur. ]
[Question] [ In an upcoming writing project, I will be focusing on an autonomous drone that picks through space wreckage. It has access to intermittent star light, but has no source of chemical propellant. The story is in the very distant future and the drone effectively has infinite time to perform its task. What sort of propulsion system might such a device employ that would offer reliable, predictable control including propulsion, braking, and rotation? Would it be as (finger quotes) *simple* as focusing the emission of photons? Are there other alternatives? Systems that would be glacially slow are in keeping with the theme, although faster or more agile systems are worth noting as well. Specifically, I am looking for a list of proposed propulsion systems from actual experiments, theoretical physics, or from established science fiction. I am not looking for opinions on different systems. Links or references would be helpful in order to more fully explore the available options. Edit: In a video, Scott Manley indicated that rotational devices have a maximum speed and can become saturated, and another force must be applied to relieve them. This isn't a problem in this context because the device has massive objects to push against. [Answer] Any light source is a propellant-less drive (often called a "photon drive"), it's just extremely energy inefficient. With perfect conversion efficiency, the impulse of the device is (energy supplied)/(speed of light) and the thrust is therefore (power supplied)/(speed of light). That is, a 1 kilowatt photon drive offers about 3 micro-Newtons thrust. Really good LED light source get near 40% conversion of electrical energy to light energy. Any inefficiency in conversion of electric power to light results is a corresponding loss of thrust. --- No one has actually deployed a designed photon drive in which a on-board light source was used as a rocket, but: * Test-bed scale solar sails have been deployed and work fine aside from the very low thrust to mass ratio. * The [Pioneer anomaly](https://en.wikipedia.org/wiki/Pioneer_anomaly) is considered solved in terms of a asymmetric thermal photon flux arising from heating in the probe's RTG. [Answer] At this time there are no working propellantless thrusters that I know of1. The closest would be an [ion thruster](https://en.wikipedia.org/wiki/Ion_thruster). However, there are some other technologies. * [Resonant Cavity Thrusters](https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster) (also known as EmDrives) use microwave emitters inside a cavity to produce thrust from a magnetic field. This one is [being tested by NASA](http://www.popularmechanics.com/science/energy/a22678/em-drive-cannae-cubesat-reactionless/). * A [Gyroscopic Inertial Thruster](https://en.wikipedia.org/wiki/Reactionless_drive#Gyroscopic_Inertial_Thruster_(GIT)) could theoretically move an object by leveraging the natural tendency of a gyroscope to right itself. * [Quantum Vacuum Thrusters](https://en.wikipedia.org/wiki/Quantum_vacuum_thruster) use the quantum vacuum fluctuations of the zero-point field to produce motion. There may be others. You could perform a Google search for "reactionless thrusters" or "propellantless thrusters" to see. --- 1 *But the Resonant Cavity Thrusters are close...* [Answer] This probe could use a combination of a solar sail to get to a debris field and the use of electromagnets once it is near debris. By using multiple electromagnets with very well-calculated "bursts" of attraction and repulsion from various pieces of metallic debris, the probe could slowly make it's way around the debris field. Imagine an architecture with several "arms" which have electromagnets on them. One might be pushing at the same time another is attracting. By powering the magnets in very controlled bursts, the probe would be able to alter it's trajectory. Side effects would include throwing pieces of debris off their own orbital paths, but if the debris field is not over a populated planet, that is not such a big problem. There are actually a number of metallic asteroids in the asteroid fields in our solar system, which makes this not totally implausible, especially if the drone was designed to operate in asteroid and debris fields. [Answer] **What is the drone's range of operations?** Where the drone is, and what kinds of celestial bodies are nearby, will drastically impact the propulsion options available. Things that will work *everywhere* are essentially limited to various kinds of reaction wheels and photon drives. Reaction wheels are great for changing orientation, and pointing the photon drives, but won't actually push you anywhere. While there are a few far-out options being investigated, e.g., by NASA's Breakthrough Propulsion Concepts program, there are currently no other propellantless propulsion systems available within the realm of known physics. However, if it has intermittent access to starlight for power, might it also have access to *stellar wind*? If so, the drone may be able to use a magnetic sail for both propulsion and breaking. Unless you have a large array of magsails, thrust will always be away from the source star in that case--tacking against the wind, like you can do with a solar sail, doesn't work so well with magsails--but that can still be useful, especially if the drone is intended to engage in interstellar travel, and needs a cheap way to decelerate into a target system, and a boost for leaving a source system. If the drone is ever in the vicinity of a planet with a magnetic field, or sufficiently close to a star to make use of the star's magnetic field, then the probe could use an electrodynamic tether both for propulsion and breaking (in which case, it would generate excess power, which could be directed to a photon drive or for other purposes). This would be most useful for spiraling in towards or out from the host planet/star. If the drone is capable of giving itself a net electric charge (for which a simple electron gun would suffice), then it could manipulate its charge to generate turning forces in magnetic fields as well. This would even be useful for interstellar navigation (perhaps more so than for maneuvering around a planet), if the drone has access to a reasonably good map of the interstellar magnetic environment. Turning in the galactic magnetic field by charging the ship is an approach that has been considered for some interstellar exploration mission designs as a means of allowing the ship to approach the target star "from behind" and thus make use of a laser sail, powered from the home system, for both acceleration *and* deceleration. When the drone is in proximity to other large bits of matter (like asteroids, or comets, or the actual wreckage that it's actively looking for), there are of course plenty of "simple" mechanical options. It can crawl around, it can use shock-absorbing legs to break and "land", and it can push off with legs. A grappling device (or suite of grappling devices for different surfaces) attached to a Very Long Tether (possibly one which could double as the previously mentioned electrodynamic tether) may be useful for grabbing onto Stuff from an intermediate distance (say, up to a few hundred or thousand kilometers). Such a tether could also be used in reverse to allow the drone to steal an object's rotational energy and give it a stronger fling towards a new destination than it could achieve with legs alone. [Answer] JBH has them pretty well covered. I am fond of the Quantum Vacuum Thruster. Another one that involves shooting stuff: **Reverse fusion ion drive** <http://www.halfbakery.com/idea/Reverse_20fusion_20ion_20drive#1276103681> Accumulated energy is used to form mass (perhaps small and easily acceleratable electrons?) which is then accelerated away to propel. It is not a very efficient use of energy but you can accumulate a lot of energy with infinite time. Glacially slow might apply. One more is the notorious **Alcubierre drive**.(<https://en.wikipedia.org/wiki/Alcubierre_drive>) This is usually invoked as a legitimate way to move faster than light by warping space in front of the moving object. Objections to this are the vast amounts of energy it would take and very energetic and destructive particles it might produce. But there is no reason this same mechanism could not be used to move slower than light. It would be safer. This concept is bandied about here: [Using an Alcubierre warp drive strictly for sub light travel](https://worldbuilding.stackexchange.com/questions/23561/using-an-alcubierre-warp-drive-strictly-for-sub-light-travel) [Answer] I'd suggest the simplest and cheapest of them all: gravity. Recall that gravity pull is zero only at infinite distances. For convenience of the story, the drone will always be under the gravity pull of some celestial object. The drone can design very elaborate gravity assisted maneuvers, planning fly-by next to the same space wreckages over the course of many millennia, if needed to. The only energy required is to run the drone brain to perform all the calculations. The drone can design its trajectory by: 1. modifying its shape: extending parts of its body (via arms, rails, ropes, threads), ejecting them via springs mechanisms (and rejoin aeons later), redistributing the mass within its body to increase, or decrease the angular momentum 2. attaching and detaching from other objects: attaching to a piece of the wreckage to increase the mass, mechanically release a piece of the wreckage to impart itself an acceleration in the opposite direction, forcefully impact on space debris to cause a deceleration, or even to self impart a spin, or correct the current one 3. timing a hitchhike on large astronomical bangs and ride on the supernova shock-waves like a boss 4. heat up (lasers!) some celestial bodies to force them to eject mass, and thus make them move. All these activities are pre-planned aeons in advance, as the drone calculates its infinite path through the universe. The secret to success is the infinite amount of time available, and enough celestial bodies to keep moving around. Forever. All in all, given infinite time, a truly intelligent drone may never need to brake. [ for the nostalgic, think of an intelligent version of the [Voyagers](https://en.wikipedia.org/wiki/Voyager_program) ] [Answer] ### There is only one propellant that imparts momentum and has no rest mass And that propellant is photons. [Photons](https://en.wikipedia.org/wiki/Photon) have a momentum of $$p = \frac{h}{\lambda}$$ Where $h$ is the [Planck constant](https://en.wikipedia.org/wiki/Planck_constant) and $\lambda$ is the [wavelength](https://en.wikipedia.org/wiki/Wavelength). There are plenty of problems with photonic engines, which I discuss [here](https://worldbuilding.stackexchange.com/questions/56975/could-a-photonic-engine-actually-work/56984#56984). But if you want no-fuel propulsion in a fact-based manner, this is the only way to do it. Your propulsion unit is basically a laser. You point the laser in one direction, fire it with very high power, and you are imparted momentum in the other direction. [Answer] Your drone has access to both starlight and shipwrecks, so a fairly simple solution would be to have it harvest from each shipwreck it visits and create slugs. It can then use those slugs as "propellant" by firing them out of [railguns](https://en.wikipedia.org/wiki/Railgun) or [coilguns](https://en.wikipedia.org/wiki/Coilgun) arranged around its body. Firing a rail- or coilgun only requires some sort of ferrous slug and a bunch of electricity, which is well within the drone's means. There's a related question about the feasibility of railgun propulsion [over here](https://space.stackexchange.com/questions/16610/is-railgun-propulsion-being-researched) on space.se. This makes even more sense if the drone has effectively infinite time to complete its task; after all, something that's expected to operate on the timescale of "forever" is going to have multiply redundant self-repair functions which can easily be turned to the task of harvesting materials from wrecks and creating propulsion slugs. ]
[Question] [ I wish to clarify my doubts regarding time dilation Is it possible for a planet to be habitable like Edmund's planet from interstellar, which has somewhat similar gravitational force as Earth (9.8 m/s^2) and has time dilation with the time on that planet slower in the rate when compared with the time on Earth. If it is possible, **what could be the reasons for it to happen?** Note: 1. The planet is not orbiting any black holes. 2. Let us consider that 1 day on that planet would be 2 on earth. 3. Similar g force is for the reason that humans could even inhabit that planet. [Answer] **Time dilation comes from gravity and/or velocity.** Since the planet is not orbiting a black hole it would either have to orbit **another super heavy mass** or **fly through space with a lorentz factor of 0.5** (when seen from earth) as that would equal time dilation of a factor 2. $t\_{planet} = \gamma \* t\_{earth};$ with $\gamma$ being the lorentz factor of $\gamma = \sqrt{1-(v/c)²}$ with $\gamma = 0.5$ the velocity is $v = 0.866 \* c$ This means your planet would have to travel with 86.6% times the speed of light. **EDIT:** as Raditz\_35 pointed out > > It should be worth pointing out however that there is absolutely no way that planet would be habitable. Let's forget about the event that made it go that fast, space is not a vacuum and stuff would bombard that planet at insane speeds > > > **EDIT:** Bridgeburners pointed out that since it's time dilation by velocity and not gravity you have to take into account that it is a more difficult scenario and the perceived time changes strongly depending on the observer. I did not properly clarify that this might not be the effect you were going for. [Answer] Your universe has a much, much lower speed of light than ours. Say, 1000 meters per second. Relativistic effects become dominant at attainable speeds. [Answer] ArtificialSoul gave a great answer. But there might be another way. The planet could rotate really fast, like REALLY REALLY fast. Obviously centripetal forces would tear it apart unless... the planet is also really really massive. Being massive and dense would negate the requirement that the planet has similar surface gravity to Earth, however you could make it so that at the equator the combination of centripetal forces and gravity gave out at least an apparent Earth gravity. I'm not sure this extreme Mesklin-like planet could physically exist (let alone naturally develop), I might come back later with the math when I have time, I didn't really give it much though. If possible, only the equator could be habitable, with gravity increasing and time dilation decreasing the more you move toward the poles. No freaking idea what the sky would look like, or what the consequences of having part of the planet age faster than others. Will think about it [Answer] How hard does your science have to be? Because if the answer is "not at all," then there's the ever-popular hand-waving effect: The deep, in-universe, answer can be something like: > > Some millions of years ago, an advanced and unknown alien race required a laboratory with specific pseudo-relativistic conditions. They used an unknown technology to generate a localized time-like metric and tied it to the world (or solar system) at a quantum level, to ensure that the planet (or solar system) didn't travel outside the time-like metric for the duration of the experiment. > > > When the aliens were done with the experiment, the forgot to switch the effect off, so today we use the world because X. > > > Or maybe the experiment isn't over yet, and the mice are going to be really hacked when they come back and find out we've skewed their results... > > > While the answer that the characters know can be: > > We don't know why it's like this, but boy it's useful for X! > > > The difference between the two can be the story in itself. Ultimately, unless the *how* is crucial to the story, it's a minor detail and can be hand-waved away. It's not my favorite method as a reader, but it does occasionally help to make the implausible into the plausible. ]
[Question] [ An exploratory spaceship holding strangers from many cultures and races has a problem leading to escape pods being deployed to a nearby world that is conveniently survivable. The pods crash land in at least two separate points on the planet, no way of telling where or how far apart, and because it's convenient to the plot burn to the ground taking all tools and supplies with them. Group A, due to luck and basic survival training, has within a few months gotten comfortable in the sense they are reasonably sure how to eat and not be eaten tomorrow and have a good place to sleep tonight when they find a radio. A simple bright yellow unmarked box with a solar panel on top. It permits talking to the ship who will translate and forward messages, nothing else. They find a hello from Group B and establish communications as quickly as possible. Group B is or includes a master survivalist specifically trained to deal with situations like this one. He found his red, spherical radio right after the crash and has been hoping for a call. Based on his training in school he has learned how to: 1. Figure out his position 2. Teach Group A to find their position 3. Figure out units of length, mass/weight, and volume (these aren't arbitrary, they would be the same units another expert would arrive at if they were part of Group A) 4. Communicate those units to Group A (so he can ask them to gather the bits needed for the beacon that gets them rescued or whatever) I want to know how he could do 1-4. For this question we are concentrating on: Could he figure out units of length, mass/weight, and volume and if so how? If you can I'd like sub mm precision. You can assume the master survivalist has at least neolithic tool making skills and a firm grasp of things like math at least in areas that would apply to the problem. I should have put this in before: Groups A and B could not see each other's burning escape pods flame or smoke after landing and they burned long enough the clearer headed could climb to the closest high point and look. [Answer] My presumption is the "radio" is like a real radio and translation is accurate and effectively instant: There is no significant delay. I presume the planet is normal, rotating (not tidally locked), and orbiting a star. Edit: We can deal with delay as long as it is reasonably consistent and/or not very long; we can measure the average round-trip time for a response (a ping in network terms), presuming the other side is constantly monitoring. **Position:** For two groups effectively anywhere on a strange planet, even on opposite sides of it; positioning is going to have to be accomplished by solar and Constellation position. First we can establish (by radio) our relative Longitude; similar to a time zone on Earth; by measuring through the radio the timing of high noon, meaning zero shadow for an upright pole. (noon because sunrise and sunset can be confused by being on mountains or in valleys). **(upright):** water can find a level on a plain; or show how to make level; and right angles are easily constructed to insure the pole is at right angles to a level field. Water in a long thin channel or tube will suffice. (We can also ensure a noon stick is plumb with danglers (free weights on long threads, thin ones (think like heavy needles) extending very slightly away from the pole in 8 compass directions, from close to the top of the pole; they must not touch the pole; and the pole should be perfectly centered in the vertical channel they create.) We have two natural directions; the sunrise direction and sunset direction. If my sunrise is after yours, I am in the sunset direction relative to you; and vice versa. However long a day is (sunrise to sunrise from a given position is best) by any measurement of time, the difference in the time of high noon tells us how far around the planet the other group is. Facing the sunrise, at right angles, we can call North on the left and South on the right. **Latitude**: this is the position between the two axis points of the rotation; our north and south pole. This will be less accurate and require sun angles and / or constellation angles. The Noon stick, for example, halfway to the North Pole, will *never* have a zero shadow if it is plumb: (Presuming the planet equator is in line with its sun, like on Earth; but the math is still deterministic of that is not true). The noon stick radiates from the center of the sphere; so if it isn't near the equator, it will always cast some shadow. The shape "cut out" by that shadow throughout a day can tell you how far you are from a pole, and the direction of the equator: At the equator, the shadow is a simple line. Well north or south; the sun cannot be directly overhead and the shadow will always have length; its *shortest* length is noon; and that must always fall on the same side, and opposite that side is the direction of the equator. To find each other, head for the equator. **Length:** Slightly tougher; you need a very tall noon stick! on the order of ten to twenty feet. Different lengths for the two groups is fine; but you need enough so you can distinguish a fine difference in length for sticks that are a significant difference apart; as I will explain. The length will be, for example, a few arcminutes (an arcminute is 1/60 of one degree, about 1.16 miles on Earth). The point is that we want **two** Noon sticks, separated by some number of miles (but not so far that people cannot signal each other from end to end). What we seek is the distance that causes a specific, small **percentage** of change in the length of the shadow. (Because that percentage is actually the tangent of an angle). The line from the shadow tip to the top of the noon stick is the hypotenuse of a right triangle. Without measuring the sides (pole height and shadow length) we know their ratio, by any arbitrary measure (like the width of a piece of straw), is the tangent of an angle; and a specific tangent implies a specific angle. i.e. the tangent of 1 degree is 0.0175, or one part in 57.29. For one arcminute, we need one part in 3437.75; so we want our noon-stick to be measurable to that precision using any found object that is quite thin. That can include, for example, thread from clothing: Tightly wound, we can get over 100 threads per inch; so to get to 3437.75 threads would just mean 34.3775 inches which is less than a yard. To be accurate, I'd probably like my noon stick to be about 10,000 threads tall. (The 'inch' is just for your reference; the group measures both stick height and shadow length in threads, period; and takes the ratio: The measuring unit cancels out to reveal the tangent). The point is we can, now, measure an arcminute (or any specific angle) worth of planet on the ground: We want noon-sticks (which can be different lengths) separated on the ground, far enough apart to be at least an arcminute apart. We can then measure that distance; say 1.16 miles, or 6143 feet. Again, it doesn't make a difference how the group measures this; they can have different units of measure. Measure it in threads. (If you wind up 1000 threads on a straight piece of stick; you can cut something like another stick to precisely that size (with a little sanding using a stone), and use that to measure things in 1000 thread units. Meaning you don't have to wind thread to get to 1.16 miles long). The point is that 1 arcsecond of planet is **the same distance** for both Group A and Group B, there is only one planet! Subdividing that distance will give them an accurate **common** measurement of distance; say dividing it by 100,000: On Earth that would be what we call 0.73723 inches. Both sides can do that sub-division and call that their standard unit: Maybe 74 of the threads used by Group A and 86 of the threads used by Group B. It does not depend on the threads used, or the size of the noon-sticks used. Now you have a standard measurement, call it a "fleck", and volume is measured in cubic flecks. Weights are measured as the weight of water in a cubic fleck, and also call that density 1.0. Other densities are the weight of a cubic fleck of the substance, divided by the weight of a cubic fleck of water. And so on; using the metric system as a guide to compute other types of measurement (heat, energy, etc). [Answer] # Everyone who has handled rope or cloth knows how long a metre is. It's the length from your nose to your outstretched hand or some other similar distance. People who walk a lot know how many strides make 100 meters for much the same sort of reason. Your man is a survivalist, he knows how to measure a metre. Metric is great. 1 litre of water is 1 kilogram. 1 litre is a 10cm cube. 1 cubic metre of water is 1 tonne. Make some sort of container on with a known volume, fill that with water to get a known mass. To be able to travel together, the various groups will have needed to use a standardised measurement system. Metric or not, it doesn't matter, there will be equivalent relationships, though perhaps not so simple. # Figure out their position 3 points, triangulate for position. It's a standard navigation skill that every child is taught in the scouts, that's if they have maps. If they don't have maps, it has no meaning. Your location is defined as your position relative to a datum, another known position. With no datum they have no location. All points on Earth are defined relative to 0,0. A spot in the middle of the ocean directly south of the naval college at Greenwich. It's ultimately arbitrary, but it gives meaning to a location. # Teach group A how to find them I suggest that unless group B has injured persons, group A has the better established position and group B should be trying to find group A. No matter which group does the searching, only one group should move, the other must remain in their declared location. If they don't have maps then they're going to have to use some old fashioned navigation skills. * Both groups need to make a [sextant](https://en.wikipedia.org/wiki/Sextant). Using their radio communication as a time signal, this can be used to find their relative positions on the planet. * One group sends a ping at their noon with the sun's angle above the horizontal, the other group measures solar position at their noon. Since communication is by answerphone message there will be a little delay getting the ping but that's acceptable for the level of accuracy involved. There is a message on the system or not. Once there is a message on the system you know the appropriate time has passed, the time between your last check and your current check is your error margin. If it's less than a few minutes then that's as good as you need. The relative angles above the horizontal at noon gives latitude, the time to noon gives longitude. Neither group needs to know where they actually are, only where they are relative to the other group. The distances to travel are arc sections of the planet, not necessarily fixed known distances, but given the initial conditions, a sextant, and a time signal they can navigate one group to the other. A compass would help but is not required. *The closer you are the less important the time signal becomes and the more important your accuracy with the sextant becomes. The trick is to be on the same latitude and know whether you should be moving East or West rather than needing to precisely place a location.* # Being found The stationary group will need to spend the intervening time making themselves as big a target as they can. They can do this by building upwards or outwards depending on the local geography. Reasonable outward building includes marking or cutting trees, leaving cairns or beacons on hilltops, carving arrows in rocks etc. Find landmarks, follow the river to the sea, climb the highest hills around, leave marks in mountain passes. Make your presence felt in the surrounding area. [Answer] ## 1 & 2 - Location **Use the sun** Get two equal length straight branches and stick one (upright) in the ground. At chosen intervals, exchange the relative length and direction (in relation to sunrise of the branch's shadow. The relative sunrise/sunset times will tell you the relative longitudinal difference. The direction and height will tell you the latitude. These will only put you vaguely in the right vicinity since we're doing it with sticks but a large fire should be able to draw the attention of your survival expert. # 3 - Units Everyone knowing their height, as already mentioned, is a good idea but if that isn't satisfactory here is another idea. You have your day - noon to noon the next day - you can now split this up using a **[water clock](https://en.wikipedia.org/wiki/Water_clock)** (and, for those interested, [a video of one being made/in action](https://www.youtube.com/watch?v=Gxa_3RZq1wI)). These aren't so difficult to make and you can measure it in terms of whatever volume you're using. Now measure how many of these it takes for a day to pass (ideally test a few times but once will do if time is short), you can use a stone to mark your container to show when different times have passed and agree these with your team on the other end of the radio. Now you have the basis for all sorts of experiments. A pendulum's period depends on the length (and some constants), work out the time it takes a pendulum to swing, vary lengths and you should be able to agree with each other on how long a particular length of pendulum takes to swing and so know you have the same length. This could be defined as the length it takes for one period to be a thousandth of a day...or some such measure, however you wish to split up your days. Now you should probably just use standard measures, as Seperatrix says: > > Metric is great. 1 litre of water is 1 kilogram. 1 litre is a 10cm cube. 1 cubic metre of water is 1 tonne. Make some sort of container on with a known volume, fill that with water to get a known mass. To be able to travel together, the various groups will have needed to use a standardised measurement system. Metric or not, it doesn't matter, there will be equivalent relationships, though perhaps not so simple. > > > But if you don't want to here are some more ideas: For mass you need a rope hung over a tree. On one side will be the mass you want to measure and on the other the top of our water clock. Fill the water clock such that the weights balance and, from a measured height, let the water begin to drain. As the resistance against gravity slowly reduces your weight will begin to fall. Measure the time it takes to hit the ground and you have a precedent for mass. As long as you both agree on time and length you should be able to determine particular masses. # 4 - You have been communicating the whole time so should both know the units you're using [Answer] **1. figure out his position:** Easiest step: Find 3 distinctive Landmarks in your surrounding. Interpolate your position between them, communicate that to group B. **2. teach Group A to find their position:** Tell them what you did. Hope they have some distinct Landmarks also. Or via position of landmarks relative of sun at a certain time. If you don't see the landmarks you can use relative height of the sun and apparent time of day to approximate position of the groups relative to each other. **3. figure out units of length, mass/weight, and volume:** Probably everybody knows his own height (From which you can make a meter) and roughly his weight. From that you can determine your volume (Water displacement for example). **4. Communicate those units to Group A:** This is harder since you want to have a conversion factor of 1 between the groups. Height is not much of a problem. You could for example measure how long a drop of water needs fall down your height and tell group A that so-and-so many seconds a drop needs to fall a meter. How do you get seconds? Have group A set an arbitrary time unit that roughly resembles a second and have them transmit the clicks to group B for the drop measurement Since you both now have a distance unit thats roughly the same, for weight you can tell them to measure a volume of water which is the same as yours to get a weight unit. **EDIT: Logic error** I think your question has a logical error tbh. There is no use for the two groups for point 3 and 4. For now, all they really need to know is where the others are to meet up with them. Once they have physical contact, exchanging the other measurement systems is easy. [Answer] ## [Pendulum](https://en.wikipedia.org/wiki/Pendulum) The wiki article alone is exciting reading, considering how many different pendulum systems were over time, with different uses, different properties of those systems. When using it as a plot device for determining length, you just limited by the wish how complex the system can be and how much work they should put to make the system and extract results. According to the wiki article, it was proposed to use the pendulum to establish a unit of length based on pendulum properties, before it was become known that gravity varies slightly from place to place. And it took them some time to measure the variations, so you can imagine how small is the difference. They may or may not know parameters of the planet and thus by measuring angles of stars and sun and synchronizing over the radio they can determine their latitudes and eliminate the uncertainty involved by rotation of the planet thus precision will be limited by local deviations which is relatively small. Gulf gravimeter in the article reported being able to measure gravity with the accuracy of (0.3–0.5)×10−7, thus if we assume equal gravity and account things we can account, the accuracy can be length accuracy. Pendulum was a part of clock design for a long time, and I definitely saw on the YouTube the instruction of a master survivalist how to make a pendulum clock, [ClickSpring playlist, Making A Large Wheel Skeleton Clock](https://www.youtube.com/playlist?list=PLZioPDnFPNsETq9h35dgQq80Ryx-beOli) Pendulum system does not require precise intervals or time interval synchronization because you can measure not a single time interval, but many time intervals, basically as much as you would like to have, but at least you count oscillations of a minute or two and compare the number of oscillations in the period. Also, it allows fine tuning of the length with simple means - [regulator](https://youtu.be/2Nle33eb1Uo) **NB** clock making does not require common measuring system, they can choose arbitrary unit at the initial stage. ## Atmospheric pressure If you have pipes you can make atmospheric pressure gauge, for water you need about 10m, for mercury about 0.760m. Mercury gauges are relatively simple if you have glass and have ores of mercury. Mercury extraction is just heating the ore in enclosed vessel and condensing it. [Cinnabar](https://en.wikipedia.org/wiki/Cinnabar) is mercury ore (HgS) - has very distinctive brilliant red color. So if you would like them to do some digging. Measuring pressure is also useful to forecast weather conditions, so they may wish it to have for those goals too. By averaging pressure values they can establish precise enough units of length. ## [Eratosthenes](https://en.wikipedia.org/wiki/Eratosthenes#Measurement_of_the_Earth.27s_circumference) They may or may not know the circumference of the planet, but they can measure it in initially arbitrary units by repeating the experiment. You can use the way if you would like them to travel a lot(far enough) ## Precision, what is enough Practically you do not need a super high precision of establishing those units, they should be about right. If the master survivalist is willing to guide the group A to create their means of survival the units has to be about right but not necessary the same. The reason for it is that methods of producing and manufacturing things do not depend on the unit of length most of the time. They begin to be more or less important in things where tensile strength is important and safety factor is low (stressed constructions used to maximum of their capabilities) It might be important to have a master length in each location, and it might be important to have similar lengths to make fewer adjustments later when they synchronize their master length by exchanging physical object. 0.1% accuracy in establishing initial units means 0.1mm difference of a 10cm detail or piece of machinery - in a lot of cases, it's not a bad accuracy, especially for simple machines and devices. And realistically speaking if they start from zero, such accuracy is just great. It is definitely a good accuracy for up to 1900-1920 tech levels and in a lot of cases today. And if you build engine, and if you have only one factory, it is important to have the master length in the factory, if you produce multiple copies of the engine or wish to have a repair kit for the engine. But that all is about having accurate repeatability, not about the absolute length of the unit. And those master length has started about that way, not exactly informative in terms of how to do things but interesting in terms of piece of history [Don Bailey, at A.A. Jonson metrology quarters](https://www.youtube.com/watch?v=mKzFXJCryrU) Also, I recommend another master survivalist and his playlist for different techniques, prototyping/manufacturing techniques for lab applications from [Dan Gelbart](https://www.youtube.com/user/dgelbart/videos) ## Precision It is possible to make DIY lasers such as [Carbon dioxide laser](https://en.wikipedia.org/wiki/Carbon_dioxide_laser), [Ruby laser](https://en.wikipedia.org/wiki/Ruby_laser) [Synthetic Ruby](http://www.madehow.com/Volume-4/Synthetic-Ruby.html) interesting article about subj. Another master survivalist talks about methods used to make crystals, [Lab-Grown Rubies and Sapphires: Flux Vs. Flame Fusion](https://www.youtube.com/watch?v=a0N4JYN9lFI) So, starting from relatively imperfect measuring length they can develop means to establish length unit in wavelength units without exchanging physical implementation of the length. And this is another reason to not seek for exactly precise units from the start. Anyway, people need time to learn skills and knowledge before they can implement and learn technologies which require precise measurements, and when they master skills they can create equipment which allows them to establish length in wavelength units. It will require optics, lasers, mirrors but not so much of electronics as an example(zero electronics). It might be not that precise as we might do today(or better to say convenient to measure and replicate the length and account for temperature and such), but precision will be more than enough for most of the shops and factories of today. [Answer] The trick to precision units is to start big and then subdivide to get small. If you start big, your inaccuracies with crude tools can be minimized. It turns out that, for most purposes, the actual size of the units isn't important. The only reason you could ever need to know the actual mass of a kilogram is if you have some re-entry documentation which gives all of the survival-related masses in kilograms. For everything else, units are really just a way of taking physical measurements and turning them into numbers (that could be conveyed over a radio). As everyone has noticed, the first thing you want is a clock. Why? Because its the easiest place to start with this system. Build a water clock, or a pendulum, or anything of the sorts. However, we're not going to try to build it to any specification. Instead, we're going to calibrate it. Build a pinhole camera that you can use to track the sun's position. Lock this pinhole camera down as best as you can, so it can't move. Using the radio, pick a time of day and mark the position of the sun at that moment (if you're too far apart, and there's no time where both of you have daylight, this synchronization process will have to be done later, and it will be harder). This is your epoch mark -- all time points are measured from that point on that day. Time durations will be measured in days. Now, let your clocks run for several days straight. Observe the time the clocks read N days later, when the sun crosses the epoch line again. With this, you can create a conversion ratio from clock readings to days. You can now use this clock to subdivide time. For example, if you had a water clock that you had to refil 400 times in the 4 day period you tested, that lets you know that each refil is 1/100th of a day. Now you can use this information to try to build shorter timepieces. Calibrate each one to the master clock's time, which itself should be periodically checked to make sure it lines up with the true master clock - the sun. The next step is to get a length standard. For this, we assume that the altitude variances in the planet have a marginal effect on gravity. If you can haul the radios around, this is easy. Grab a bunch of decent sized boulders and head up to a larger cliff. Orchestrate between the two sides until you can find a cliff on each side where if you release a rock at the same time, it impacts at the same time. Mark this point in space. The distance down from this point to the bottom of the cliff is your reference distance. Now you can use trigonometry to subdivide this length. If you can't move the radios, you'll need those clocks. Agree to find a cliff that is some fraction of a day's worth of a fall. You can build a small clock and tune it while you're near the radio, and then take it out to find a cliff. Now you have time, and length. Length quickly means you have volume. Most importantly, you have time, length, and volume defined on very large scales, where crude human errors have been minimized. You can now scale these down independently of eachother. Make faster clocks, make shorter length measurement rods (using right triangles). Whenever there's any question about lengths or times, you return to the original reference (the cliff or the master clock) and re calibrate. Now the hard part's up to you. I conveyed time and length. Now you have to do, you know, the whole survival on a hostile alien planet thing. Seems far more difficult, if you ask me. [Answer] From the question, I thought they really had very few tools if any, in which case, why would you need mass and volume? Did I miss something? Step 1. You walk until you get a good view and find a nearby landmark. Step 2. You estimate how many days or partial days it will take to get there. Step 3. You tell everyone that information. Step 4. Even if you or they aren't quite there, you light a fire and keep it burning until everyone can make it to the source. The units of time are days or parts of days (very rough) and distance and mass aren't necessary. Once everyone it together, you can figure out units of mass/volume/time or whatever you need. Plus you can share the workload and be rescued all together. Of course, I'm assume the escape pods land in the same region. Are they on different continents or something? [Answer] ## Figure out his position Relative to what? That's the question. From the question it sounds like he has nothing but his radio and what he and his fellows can make with stone knives and bearskins. Lattitude can be determined by measuring the elevation of the sun from the horizon, which is a relatively simple measurement to make. *However*, you have to account for the axial tilt of the planet. So he's either going to have to know that, or spend a year taking measurements and then do a bunch of trigonometry to figure it out. Relative lattitude compared to the other group though won't care about axial tilt as long as the measurements are taken within a couple of days of each other (assuming earth-like year length. The shorter the year, the more precise the timing of the measurements.) Longitude has no purely naturalistic way to measure. Mastering that one required high-precision clocks on Earth. Also, he'd have to pick a reference point... Relative longitude however can be determined just by using their radio. First, determine how long the RTT (Round Trip Time) is on the messaging. (Group A sends a message, and measures how long it takes Group B to receive and respond when everybody's going as fast as they can.) That will let them know the offset, and any variations in the timing will give you what the tolerance is, then they compare the elevation of the sun to the horizon at as close to the same time as possible. By comparing that to the length of the day they can figure out what fraction of the planet lies between the two groups and in which direction. By tracking how far the moving group goes versus how much the measurement changes over a few days, they can calculate the rough diameter of the planet and figure out how far the trip will be. If the RTT is too long, or too unstable for this to work (doubtful unless the technology itself is horribly unreliable) then they'll need to look for some event that is visible to both groups at the same time. Needless to say, this could take a while. ## Teach Group A to find their position Send the above instructions over the radio. It's not that complicated a process. ## Figure out units of length, mass/weight, and volume This is actually relatively easy if he's from a country where they still use the Avoirdupois system of measurement, and really quite difficult if he's from one where they only teach the metric standard. Make no mistake, metric is nice for doing calculations in, but it's pretty well useless if you have to make your own measuring devices out of sticks and rocks. To illustrate: Grab a pen and paper (pretend your carving notches on a stick. (Unless you'd rather grab a stick and a knife, your call.)) Draw a line on the paper and pretend it's a meter. (Accuracy doesn't matter for this, just any reasonably wide length will do.) Now, divide that "meter" into evenly sized "decimeters" (tenths). Good luck. Using nothing but your pen and paper, it will take you hours to get it reasonably close. Then do it again to one of the decimeters for centimeters... Now, the secret is that the human brain is remarkably good at dividing things in half. And it can do thirds with a small amount of practice. So, pretend your line is a "foot" and cut it in half. then cut the two halves in half. Then cut the quarters into thirds. Presto! You've got inches, and if you have any reasonable level of coordination and put a modicum of effort into it, they're probably as close to the same size as is humanly possible to draw without mechanical assistance. The Avoirdupois system is designed around fractions that the human brain can handle easily, instead of tenths. Which makes the math hard(er slightly), but the creation of measuring devices easy. And when you have to build your measuring devices with your bare hands, having the math be slightly more difficult to remember is a small price to pay. So: Find the male in the group who is the closest to 5'8" tall and normally proportioned. You will be able to derive measurements as follows: The length of his foot will be close to a standard foot. A foot can be easily divided into reasonably precise inches by hand. The distance from the first to second knuckles of his index fingers is likely to be reasonably close when in a hurry. The distance from the tip of his nose to the end of his laterally outstretched arm will be three feet (1 yard). The amount of material he can hold in his two cupped hands will be just about one cup. Two cups makes a pint. Two pints makes a quart. Four quarts makes a gallon. One pint of water weighs a pound. Using a stick and a string as a balance beam, and knowing the principle of force\*leverarm, he can divide the pound into sixteenths to make ounces. 1000 walking paces will be just about a mile. Sub millimetre precision will require crafting devices to allow more precise division of units. The process is not technically complicated, but it does require a fairly large time investment. You used to be able to get entire books on the techniques from Lindsay Publications, but they've closed down for retirement, and I have yet to find a replacement source. Many of the books about how to create such devices efficiently from scratch have not been printed in any significant volume in over a hundred years, so your survival expert may or may not be familiar with them. Discovering the most efficient methods for creating high-precision tools with simple hand tools from scratch will up the time requirement immensely. You didn't specify time synchronization, but two pendulums of the same length, lifted to the same height, will swing at the same frequency. But that probably doesn't matter until later since they won't be moving fast on foot and won't be trying any complicated coordination of activities until the two groups get brought together. ## Communicate those units to Group A Have them find the male in their group who is closest to 5'8" tall and normally proportioned. Send him the instructions for how to create the measurement devices. (Yes, the male thing is actually important since men and women have different average hand and foot sizes relative to their height. Of course, the size of man specified assumes they're trying to get close to the standard measurements. If they don't care, then just pick the two individuals who are the same sex and closest to the same height.) It won't be exact, but it will probably be close enough for rough navigation to bring the two groups together. It should at least let them make precise enough measurements of relative latitude and longitude that they can get close enough to each other to be able to see the same landmarks. Simple angles between multiple landmarks should let them meet up from there. [Answer] It would be a great use for *natural units* <https://en.wikipedia.org/wiki/Natural_units> They don't depend on anything arbitrary, so they could also come in handy for sending measurements to alien cultures. ]
[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/45722/edit). Closed 7 years ago. [Improve this question](/posts/45722/edit) This question doesn't concern how it might be possible for a human to take on werewolf form. I'm asking about what impact the lunar cycle has on a human body and any other possible ideas of what might cause a werewolf to shift, not how a process of shifting might actually work. Hope that makes sense! [Answer] I don't see a science tag on this question, so I will go supernatural on this. The moon acts as a mirror for sunlight, effectively reflecting some of the sun's light back to Earth, during our night, making it a little less dark. Those sun rays that are bounced off the moon have some of their characteristics changed - they are now charged with Moon mana or something - and irradiate living beings differently. Werewolves and other lycanthropes' skins are more sensitive to this magical radiation, and past a certain level they will shapeshift. The threshold is reached and passed naturally during the full moon. A mad enough witch or wizard could maybe force such transformation by emulating moonlight in some way. See also [Blutz Waves](http://dragonball.wikia.com/wiki/Great_Ape), under *Conditions for Transformation*, for how they approached this in the Dragon Ball series. [Answer] The way that disease works, I see 2 good, realistic options; * Might be same as with wolves howling at the moon - a mistaken myth. The werewolves just hunt more often at night so it was believed that they only appear when the moon is out. The one advantage of the full moon is that the nights are brighter so you could make some argument for it needing that but it's a pretty weak one. * It's linked to some other cycle and happens to coincide with the full moon. [Answer] **I am going to go a strictly biological route.** TL;DR: *It's all hormones.* The lunar cycle is strongly (superstitiously?) reminiscent of the **menstrual cycle**. This is confirmed with a quick [google search](https://www.google.com/?gws_rd=ssl#q=menstrual%20cycle%20and%20the%20moon). It is a bit interesting that in humans, the menstrual cycle and the lunar cycle are (on average) exactly the same length. Clicking on a few of the most popular links (and as says on [wikipedia](https://en.wikipedia.org/wiki/Menstrual_cycle#The_Moon)), they have no correlation to the modern human. However, I found at least [one study](http://www.ncbi.nlm.nih.gov/pubmed/3716780/) saying there is at least a correlation, if no definite causation. Which means we have an at-least-plausible example of very strong hormone change/cycle being caused by the moon. A lesser example is simple [circadian rhythms](https://en.wikipedia.org/wiki/Circadian_rhythm). Although to be called "circadian" they have to last about a day (24 hours), there are other rhythms that last different amounts of time. Circadian rhythms are most strongly associated with periods of light vs darkness (especially natural light, from the sun). So we, as humans, are already at least slightly influenced by the movements of our celestial neighbors. Obviously the association with the moon is very, very faint so as to be indistinguishable in modern times, and the association with the sun is easily negated by artificial light, but the influences are there. I always imagined werewolves to have similar influences, but for them to be **a lot** stronger. Instead of, say, ovulating and bleeding at a certain time of month, the werewolf's celestially-dictated hormones cause the lycanthropic change. If you want this only to happen at night, you could also have the hormones connect with the sun as well as the moon, circadian-like. --- **Post-answer thoughts** How would the infection happen? Assuming we are going for a werewolf's bite causes the wounded to become a werewolf, I think the simplest would be a virus. The virus infects the host's hormone-producing organs to produce the hormones necessary for lycanthropy, and off we go. If the infection can only happen during the shape change, it's simple to only have the virus present in the saliva when the hormones dictate the change. This would also give the potential for a cure (or at least a treatment). After all, if all it is is hormones, birth control is a very simple form of hormone therapy, and it has radical influences on menstruation. [Answer] In IMDb's description of [Werewolf of London](http://www.imdb.com/title/tt0027194/faq), a movie from 1938, it says... *While in Tibet looking for a specimen of the Mariphasa lupina lumina, an obscure phosphorescent plant that only grows in the mountains of Tibet and blooms in moonlight, botanist Dr Wilfred Glendon (Henry Hull) is attacked by some kind of animal...* What if it wasn't the animal attack which made Dr. Glendon a werewolf? What if it was caused by the flower's pollen, which only comes out in full moonlight? It is therefore not the moon which calls the wolf; it is the moon which calls the flower which calls the wolf. [Answer] It's the UV light and, thereby, the feeding cycle. The light of the moon is reflected sunlight. This light extends into the ultraviolet spectrum, which most humans can't see into, but [canines can](http://io9.gizmodo.com/superpower-vision-lets-cats-and-dogs-see-in-ultraviolet-1525842007). And what does this allow them to do? To more-easily see and track prey, relying on signs that don't show in the regular spectrum: > > "There are many examples of things that reflect UV, which UV sensitive animals could see that humans can't," co-author Ronald Douglas told Discovery News. "Examples are patterns on flowers that indicate where nectar is, urine trails that lead to prey, and reindeer could see polar bears as snow reflects UV, but white fur does not." > > > A reindeer, a cat and a dog could therefore probably see a white-furred animal, such as a bunny, hopping through a snow blizzard, while most people would just see a blur of all white. > > > Therefore a werewolf's best meals will come by the light of the full moon -- and on that night a werewolf could be satiated for a month. (It'll still eat in human form, for both biological and social reasons. But the big, glorious feast comes once a month.) A werewolf could turn at other times, but it's not worth it -- turning takes a *lot* out of the werewolf physically; he needs a few days to recover enough to do it again. To one who can see into the UV spectrum, though, the full moon *really* lights up the night sky. (Source: personal experience.) So a werewolf will restrain himself as the moon waxes full, holding it until the right night, and then go for it. The moon doesn't turn werewolves; the moon is the cue. [Answer] Just like the moon pulls up tides, it pulls out the wolf hiding inside the human. All humans have it a bit, as can be seen in high rates of insomnia and first-aid emergencies during the nights around the full moon. When the moon grows, something wakes in your blood. It wakes and must come out. Just like tides vary from almost non-existent like the closed-in Mediterranean to the pace of a galloping horse on the coast of Normandy the top of the range comes out as full-blooded lycanthropy. [Answer] The full moon makes it lighter at night. Humans were once preyed on by large cats. Cats can see better in the dark than we can, but they cannot see in total darkness, nor well by mere starlight. Ditto wolves. So we may be wired to be more alert, more jumpy, less able to sleep soundly, when the moon is full. And wolves may be wired to go hunting. There's a grain of truth to the belief that mental patients become more disturbed under a full moon. Easy to deny primeval instincts and reflexes, but they are still there. Why do we get hiccups? Apparently the neural pathway is something that was very important for a fish. The vestiges persist. Maybe in a werewolf the human and dog reactions to the lunar cycle synergize? [Answer] I'm going to go with legal issues on this one. In werewolf society for reasons that might seem archaic to the latest generation, it is illegal to transform except during a full moon. Physically, any werewolf can transform at any time, but the fines, red-tape, and social ostracism that come with breaking from tradition ensure that the majority of well-behaved werewolves will only activate their transformation during a full moon. [Answer] Having studied how the moon might impact humans, I think I can give you some insights. Taking from a biological perspective, the moon does indeed affect animals: <http://www.livescience.com/37928-ways-the-moon-affects-animals.html> From this, some creatures set particular biological processes, such as the coral reef's reproduction, on the full moon. Furthermore, the moon has a weak magnetic field: <https://en.wikipedia.org/wiki/Magnetic_field_of_the_Moon> And the moon is impacted by the earth's magnetotail when it is behind the earth (which has the best odds of also being a full moon, facing the sun): <https://www.sciencedaily.com/releases/2008/04/080420123319.htm> My own personal theory is the moon affects magnetite found in the human brain: <https://en.wikipedia.org/wiki/Magnetite> Magnetite in the human brain: <https://www.ncbi.nlm.nih.gov/pubmed/1502184> So from this, we could speculate that the moon affects a particular biological process, in that, in distorting or interacting with earth's magnetotail it has a knock on effect on the magnetic field of earth, causing the magnetite in the human brain to effectively change, which in theory triggers things like headaches. From a fiction perspective, you can then argue that such a change causes people to become angry, or mad (it's where we get the word 'lunatic' from: lunar), which causes them to become werewolf-esque in behaviour. In terms of physical changes, it'd be harder to justify, and you'd have to suspend any sort of hard sci-fi approach here. You could argue the magnetic field causes the DNA to transform (mostly affecting the exposed outer skin), which starts a few days before the full moon and slowly disappears a few days after. But you could go hard sci-fi and have the person act like a werewolf. Their rage triggering adrenaline would enhance their strength, which again, superhuman strength isn't unheard of: <https://en.wikipedia.org/wiki/Superhuman_strength> But obviously a physical transformation would be a step too far in a hard sci-fi. You could make it that the DNA or genes (perhaps modified by a retrovirus or even parasite?) makes the person noticeably hairier and stronger, but it would assume a permanent fixture rather than an instantaneous change. [Answer] I've seen the [idea used in such stories](https://en.wikipedia.org/wiki/Operation_Chaos_(novel)) that it is the polarized light that does it. > > Dependence on the moon is lightly tossed aside with a comment that the necessary components of moonlight (specific frequencies of polarized light) have been isolated, and his Polaroid "Were-flash" lets him turn into a wolf or back to his human form at any time, its controls having been designed to be operable even with paws and no opposable thumbs. > > > However, with *any* idea that it's something about the moonlight, why is it specific to the full moon, and not just any bright moon? The full moon is brightest compared to other times of the month, but how bright that *is* depends on atmospheric conditions. ]
[Question] [ I plan to go back in time and help Asterix and Obelix to turn the tide of Gallic wars against the romans. To achive this i will build ancient versions of our most dreaded land weapon: Tanks ! **The vehicle:** Two rows of oarsman propel the tank using pulleys attached to an oar. those pulleys transfer power to a pair of brass chains that works as tracks. Above this a group of soldiers operates a set of cheiroballistras that work as machine guns. the whole tank is made of wood and covered in metal plates. **Question:** Whats the impact of such device in a war against the Romans of the time? Is this possible for the Gauls of the time? Could a development of such device deal with late barbaric invasions? Could such devices be used as amphibious landing machines against Roman foes (supposing the Romans captured one and learned how to use it)? How can they transport such a device to a battlefield? Edit: Added image ![Ancient tank](https://i.stack.imgur.com/FSfp9.png) 1 - Turret top : Soldiers with ballista, hand ballistas, onager or flamethrower. 2 - Armored box like structure containning the oarsmen. 3 - Tracks 4 - Armored Tower. Edit : What about a vehicle carrying repeating crosbows ? [Answer] Well, consider for a moment the fact that ancient armies (ESPECIALLY Rome) used the tactics that were the most expedient and cost-effective for the time. Yes, I suppose you could offer a few new ideas to the Gauls, but let's look at the drawbacks and why it might not be cost-effective: Power: You say you want to power this thing using human muscle. But humans tire VERY quickly when working with such heavy weights. This "tank" will have metal plating (very heavy), built out of wood (also very heavy), and each person added to the "engine" mechanism adds their own weight to the machine as well. Then we have to add the ammunition and ballista that make up the weapons. All of this seems like WAY too much for even the stout barbarians to handle for any length of time (meaning, this thing is going to be SLOW and have a ridiculously short range). Weaponry: Ballista were effective for their time, but remember the Romans also used them. In fact, almost every ancient society used ballistas to some extent. My point here is that, despite the fact they were widely used, they often didn't turn the tide of the battle. Superior infantry/cavalry and tactics did. The reload rate and accuracy aren't good enough to turn it into any kind of war winning weapon of mass destruction. Speed: Somewhat related to power above, one of the biggest advantages to modern tanks is the fact they can move VERY quickly across even moderately difficult terrain for many miles, especially when accompanied by a supply train of fuel. Without modern fuel and engines, this "tank" is going to be so slow, I doubt it would ever even make it to the battlefield, much less have any impact on a war. Further, the turn rate and movement speed in battle is going to be absolutely DWARFED by even soldiers on foot. Considering the Romans were very knowledgeable about siege engines, I have no doubt they would quickly find its (many) weaknesses and exploit them fully. In summary: Unless you can come up with a better source of fuel for the engine and make the thing faster, I don't think it will have much of an impact of a war against any faction, much less the Romans. There is a reason that heavily armored horses/elephants were used as "tanks" in the ancient world. They had the muscle and stamina to carry the heavy loads, while keeping a decided advantage in speed over infantry. [Answer] You are basically talking about building a sort of [Siege Tower](https://en.wikipedia.org/wiki/Siege_tower). All the reasons why your tank would not work are shown by this device. It needs incredibly flat ground to work (no way you are going to muscle-power such a heavy device up a hill), it moves really slow (due to its weight), you can't really strategically transport it (again; needs flat ground, probably cannot cross rivers) and at the end of the day it's a huge sitting duck (a wooden structure can burn, metal plates won't help unless you completely cover it, at which point's it's both unbelievably expensive *and* too heavy to move) As a defender, you are much better off just building stone towers and putting your men in those. As an attacker, the siege tower might work for its specialised goal... but then the Roman's knew that, because they built them. [Answer] # How to transport such a device? Rather than making a human-powered iron tank you could simply put a wooden box with a thin bronze covering over your soldiers, hook a few oxen up inside and connect the oxen to a series of chain tracks designed to move the thing. Unfortunately I don't have time to do the math on how many oxen you would need or material. The following picture should give you a general idea of what I mean. ![enter image description here](https://i.stack.imgur.com/HmbnC.jpg) ## Is this Possible for the Gauls of the time? **In short---no** To further explain, the native [Celts](http://en.wikipedia.org/wiki/Celts) lacked the iron working knowledge to make the tank track required. I also see in practical reason why they would go through extreme trouble of creating **1** tank when for the same amount of materials required to build it you could build ten chariots and train their crews and pay for their maintenance. Not to mention the chariot was far more effective and maneuverable. As for building a mechanical engine I suppose you could have a Celtic guy travel to [Alexandria](http://en.wikipedia.org/wiki/Alexandria) where he discovers the [Steam Engine](http://en.wikipedia.org/wiki/History_of_the_steam_engine) of [Hero of Alexandria](http://en.wikipedia.org/wiki/Hero_of_Alexandria). You could have him hire some engineers to come fight Rome by designing your [Steam Engine-powered tanks](http://en.wikipedia.org/wiki/Steam_tank) ### What impact would it have on the Romans? **Little to none.** The Romans were technological geniuses. They designed state-of-the-art weapons and would have most likely adapted the Gaulic-Egyptian technology to make an even better weapon. Even if they didn't, the only advantage would be psychological and even then it wouldn't be enough to scare entire Roman armies away. ### Could such devices be used as amphibious landing craft? **Depends.** Depends on what? It depends on whether or not the contraption displaces its own weight on the water. A real-world example of metal contraptions floating is all of modern-day ships and amphibious landing craft. Find out how they float and use that to design your vehicle. The most difficult thing to do in my experience would be to realistically and accurately describe your machine to your readers (assuming you are doing this for a story). ### How can they transport such a device into the battlefield? **It depends on how you want to deploy.** For surprise attacks on relatively flat and dry terrain you could probably just pre-assemble and roll onto the battlefield. If you want to transport across the Mediterranean region and in Northern Europe you will have to disassemble and reassemble on site which raises many many many more problems, the biggest of which is how to protect the construction sites from raids. In the children's TV show [Avatar The Last Airbender](http://en.wikipedia.org/wiki/Avatar:_The_Last_Airbender) the [Fire Nation](http://avatar.wikia.com/wiki/Fire_Nation) uses similar contraptions to protect infantry on the battlefield called [Tundra Tanks](http://avatar.wikia.com/wiki/Tundra_tank). I have included pictures for your convenience. ![enter image description here](https://i.stack.imgur.com/Y5Epl.jpg) ![enter image description here](https://i.stack.imgur.com/qteF1.jpg) ![enter image description here](https://i.stack.imgur.com/cP5fK.jpg) ### Alternate Ideas Instead of bringing knowledge of an as-so-far impossible to reach technology, consider bringing a bunch of smaller, more attainable technologies with you. I have a few examples: * [Spur](http://en.wikipedia.org/wiki/Spur)-Yeah, those sharp pointy metal thingies worn by cowboys would make a difference on the field of battle. It can make horses easier to control and as a consequence, makes cavalry deadlier. * [Stirrup](http://en.wikipedia.org/wiki/Stirrup)-This helps keep the rider on a horse and would make cavalry charges just that much more effective. I can see this making a difference in key battles such as the [Siege of Alesia](http://en.wikipedia.org/wiki/Battle_of_Alesia) where a failed Gaullic cavalry charge costed them the battle and ultimately the war. * [Arched Saddle](http://en.wikipedia.org/wiki/Saddle)- works with the others to allow cavalry-men to ride hands-free (meaning---yes, we all knew this was coming---two-handed swordsmen on horses! Almost all of the techs from [this Wikipedia page are good alternatives](http://en.wikipedia.org/wiki/Medieval_technology#Armour) that are reachable. ![enter image description here](https://i.stack.imgur.com/cAfF4.jpg) [Answer] The [Germans Tiger](http://en.wikipedia.org/wiki/Tiger_I) tanks of WW2 were much more powerful weapons than the Soviet or Allied tanks by orders of magnitude. However, they also weren't able to be produced anything nearly as quickly so the Germans may have done better producing a slightly worse tank that cost less to build. The point being, there is a real cost to building such a weapon as you purpose, one that I don't think would be worth anything like the benefit gained. The tank would move slower than infantry, certainly the calvary of the day and be massively expensive. Rome was the one with the resources, the engineers, and the logistics so that it wouldn't even matter if they were not able to directly attack your tank; they would cut off the supply route, figure out how to box it in, and then just conquer around it; or determine its weapon range, trap it, set up something with a longer range and pound it with that until it broke. Dealing with Rome's professional standing army and military engineering wasn't something that anyone actually did successfully at the time period. Basically instead of something big, you probably want to go small and give them the [stirrup](http://en.wikipedia.org/wiki/Stirrup) and improved composite bows. [Answer] Laager or [wagenburg](http://en.wikipedia.org/wiki/Wagenburg) tactics used in the past were similar to primitive tanks in some respects, although they were used defensively as mobile fortifications rather than an offensive vehicle. If you're willing to throw out the tank treads and shed the armor plating to reduce weight, why not go with a horse or ox (or elephant!) powered wagon which is completely enclosed inside a wooden box to protect the animals. Build a turret (or at least a walled platform) on the top for missile troops. Add a scoop at the front to shunt aside the bodies of enemy infantry plus caltrops and other nasty anti-horse devices. Perhaps screen the "tanks" with light infantry or cavalry to maximize the surprise factor. Unleashing a formation of such vehicles charging into infantry formations would cause complete mayhem. [Answer] **Whats the impact of such device in a war against the Romans of the time?** If you had hundreds maybe thousands of FIREPROOF versions of these you might do major damage to some Roman cities if you could get close enough. On the battlefield they would be quite useless against the Romans if any water source was nearby as the Romans would simply flood the battlefield around them and your tanks would get stuck in the mud. **Is this possible for the Gauls of the time?** No, the Gauls though fierce fighters were not capable of designing something like this. They lacked the math skills, general engineering knowledge and the whole idea of shielding themselves in a giant box kind of went against their warrior mentality. Remember many of them liked to fight naked. **Could a development of such device deal with late barbaric invasions?** No, they only thing that could have saved Rome was a strong unified Army of diverse peoples. Once Rome lost their diversity, had no one else to conquer and became a Christian empire their days were numbered. **Could such devices be used as amphibious landing machines against Roman foes (supposing the Romans captured one and learned how to use it)?** The Romans already had the box formation so unless you could drastically increase the amount of protection the tank offered compared to their box formation, allow the same speed as foot soldiers had, AND avoid giving your soldiers fatigue before they even started fighting then they would not use something like to do an amphibious landing. They would probably just use small boats to cover their heads until close enough for battle. **How can they transport such a device to a battlefield?** The Romans could if they wanted to by breaking it down into 2 pieces. They would probably carry(roll) half of it as a wall. It would make a for good defensive shield but would be extremely heavy even with wheels. Carrying it in two pieces would allow men to quickly come together and have them lock it with some iron pieces and be ready for battle. ]
[Question] [ So I wanted to write an Ace Combat type story but I'm having trouble what type of world that would explain the importance and mass production of aircraft. I tried to look at the map of Strangereal but I couldn't find any type of inspiration. The world I want to make is like an alternate modern world. It's also a multi-polar world which means that most nations and countries are equal in power, resources, and military strength. Most countries could own fighters jets and naval ships that they don't need to trade with others (just an idea but I thought that because of the ease of production of military vehicles that even mercenaries could grab themselves a fighter jet to join wars). [Answer] Instead of making the terrain flat, make it extremely rugged and broken: very mountainous, sharp, cliffs, crevices. The Alps, The Rocky Mountains. Make all the available water large lakes, a few miles across at most, but frequent. Rivers can run, but are windy with steep 10-20 foot drops every 5 or 10 miles; often ending in waterfalls. These are not great for ships. By doing that, you have disabled most land vehicles and ships. Marching armies move slowly. Only an aircraft can navigate rugged terrain quickly and easily. We can find enough land we can clear for a township, or even a mile long airstrip. But aircraft, even gliders or Wright Brother era aircraft, are the superweapon in this terrain. Air battles would evolve naturally. Below is a photo of Peru near Machu Picchu, the ancient mountainside village made of fitted stones. If your culture evolves here, gliders and machine powered flight would have enormous impacts, both militarily and culturally. They learn to glide first, taking advantage of currents, gliding alone is 10 times faster than foot travel and saves huge amounts of energy. Climb one mountain, glide to the next, even if you lose 100' of altitude and have to climb again, that's better than climbing down a 1000' and back up 1000'. People will develop fold-up lightweight gliders, and use them like we use bicycles. Heck in this terrain, they'd probably invent wheels, but may never invent bicycles; what's the point? Eventually huge gliders will be devised for carrying heavy cargo. Eventually the invention of engines to power the gliders will come along; regular aircraft and powered flight will evolve. The knowledge of how to fly, over generations with migrations, diffuses into all cultures worldwide, until the primary mode of transportation anywhere is by air. And thus the primary mode of warfare between nations is air battles. [![Peru, Machu Picchu](https://i.stack.imgur.com/bgeWD.jpg)](https://i.stack.imgur.com/bgeWD.jpg) [Answer] Large flat treeless islands or continents in large quantity, I'd say. Vast grasslands and shrublands (eg. prarie, steppe, veldt, pampas), nice for farming. Giant flat deserts, like quite a lot of Australia. Easy to put in an airstrip wherever. First for the wet navy: * Aircraft have been bad news for surface wet navies since Pearl Harbor, and antiship missiles have only made this worse. * Carriers are only needed when there's no handy airbase. * If there's more land and less Pacific, there can always be a handy airbase. * Shore-launched antiship missiles are increasingly dangerous when there's more shore and less open ocean. And for the dry army: * Long lines of sight with little cover are bad news for everyone on the ground. With no mountains and no trees, everyone on the ground is badly exposed, and no-one is going to dig trenches across a thousand miles of plain or desert. * Modern antitank missiles are pretty bad news for tanks already. * Specialist ground attack aircraft are extremely effective in the right sort of terrain. The only thing you hand to handwave away is antiaircraft missiles, and that's a bit more of a challenge. Any countermeasures to SAMs also work against regular AAMs, and potentially against air-to-surface weaponry too. This needn't be a bad thing if what you want is WWII-style gun dogfights and A10s with ridiculous cannons. --- Remember this doesn't have to be *the whole world* (which might be a bit too unrealistic), but just *enough* of it to provide an interesting setting. Maybe tanks and soldiers and carriers are the best things everywhere else in the world, but no-one cares because your [flyover continent](https://en.wikipedia.org/wiki/Flyover_country) has all the resources that everyone else wants and needs, and so that's where all the plotworthy fighting happens. [Answer] To make aerial combat more prominent, here are my choices ranked by incentive to develop air warfare. Most are inter-compatible between each-other : ## 1) Sky islands [Laputa](https://en.wikipedia.org/wiki/Castle_in_the_Sky), [Dragon hunters](https://en.wikipedia.org/wiki/Dragon_Hunters), [Sunless skies](https://en.wikipedia.org/wiki/Sunless_Skies), [trapped in a Dating Sim: The World of Otome Games Is Tough for Mobs](https://en.wikipedia.org/wiki/Trapped_in_a_Dating_Sim:_The_World_of_Otome_Games_Is_Tough_for_Mobs) (this title is so long o\_x)... It's simply a set of islands or other objects floating in the sky. Alternatively it can be floating asteroids, but reacting for people like they're on Earth. This is your best choice over anything else. Having a sky world is a very high-incentive to make air-warfare, as any other warfare isn't just viable at all. This is shown in all 4 references I gave **Why?** * There can't be any naval warfare at all, because... Well, there's no sea x). * Bridges between islands is expensive. And they get destroyed very easily. Land warfare is therefore very unreliable beyond the islands they're set on. Land troops will need air transport to conquer territory. * You don't want to fight enemies on your land, especially with key infrastructures, that's the last resort defense. Because there are always empty spaces where no flak land cannons can reach, you can't have a buffer zone to prevent this. Therefore you have to send fighter planes to intercept invasions instead. * Any commercial caravan will be in the air, therefore almost every pirate or corsair attacks will be in the air, too. * People necessarily have to invent efficient planes, helicopters and blimps to travel between islands, and therefore would have focused their research on it. **Why not?** * For a sky island world to exist you generally have to admit there is some magic or physical singularity involved. ## 2) Lava/acid oceans worlds This is a slightly less magic-prone alternative to sky islands. Take a world, replace the seas with either lava, acid, or something else which prevents boats from floating. Or its crew from living. **Why ?** * There's little to no naval warfare at all. It's one less concurrent to care about. * Like with sky islands, land warfare is contained within the land it is lying on. To provide land troops from another continent/island, you have to use air. * Infantry are removed from the game or would require very heavy support from tanks and planes to get protected from rains (acid or pyroclastic clouds). * If people do manage to bypass some of the lava/acid damage, they get access to a new cheap and effective against any unprotected or damaged land troops/structure, yet working at its most potential from altitude : [lava/acid bombers](https://en.wikipedia.org/wiki/Aerial_firefighting#Water_bombers). Bonus for lava since it solidify against any resilient structure left. **Why not?** * Living conditions are likely to be extremely hard there. Technology or/and magic requirements to just survive there is likely to be high. * Meteorological conditions are likely to be harsh, too. You can't rely very much on visual identification and do need the instruments and specialized technology to navigate an aircraft in it. ## 3) Lower gravity, 3b) higher air density This is the main element which prevents air from being used to its full potential. Make your planet less heavy, or increase its air density to make the cost of rising things up in the air much lower. **Why ?** * Drastically improves air vehicles max carry weight, which means increased armor, weaponry, troop transport or autonomy (fuel). You can have actual air tanks with more stable air frontline now. * Maneuvering with planes is easier : You can have a lower speed and you'll have an easier time dealing with stalling. Your tactical playground is also bigger (you can reach higher-places). * Take-off areas will be much shorter due to higher-lift/lower gravity : You can have more airfields with more planes taking-off with less cost. * It's much less expensive (economically and technologically) to produce aircrafts. You can have "cannon fodder" aircrafts and replacing/repairing any aircraft will be easier, much more than other troops would gain from these world changes. **Why not ?** * Higher air density can decrease airship top speeds, one of its main strength. * Lower gravity means ground and naval forces can carry more weight, too. However, they'll never get the same speed as air, and the profits of much higher weight capacity suffer from diminishing returns. * Tanks will get more armor... But at the same time they will have to use it to protect against aircraft which'll hold heavier weaponry and be more numerous. * This doesn't make airships a true necessity, rather a much stronger card to play. ## 4) Archipelagos or plain oceans If you can't remove naval warfare, think the opposite, remove land warfare instead. The principles are about the same as sky islands, just you have moving boats around now. **Why ?** * Planes work very well with ships because they cover each-other weaknesses : autonomy and raw fire power for air, speed and coverage for sea. * Planes excel at destroying key objectives. Islands and any other targets like offshore platforms are very easy to determine as "key objectives". * Because there are always empty spaces where no flak land cannons can reach, it's much harder to have a buffer-zone to prevent air invasions. You could use ships to make up for that, but they can be outmaneuvered (slow...) and are already split protecting against 2 other battle planes (sea surface and underwater), so... * You need only one plane with one well-placed torpedo to sink a whole ship and its crew. You need several bombers to kill all infantry and tanks in an area. * Difficult to land shorelines could make sea transport much trickier to do. Land assaults are likely to need the support of air. **Why not?** * You're very dependent on naval warfare, especially regarding aircraft carriers. At the very most you're split between 50% air / 50% sea warfare, if not less. * You don't have much ground to land and take-off. This severely limits the total number of planes available at one time. * This doesn't make airships a true necessity, rather a stronger card to play. [Answer] You got two examples from existing works. A world with floating islands like the Japanese game Grand Blue Fantasy. Since you definitely need to fly to get to another human settlement, most of the transport in that world is going to be aircraft or airships. Or, just like the anime The Magnificent Kotobuki, where there is very little ocean--which makes transporting goods by land possible, but very time-consuming. The existence of aircraft and airships makes transportation time shorter. [Answer] In other answers, scenarios are suggested where enemy is difficult to reach by land or sea therefore you attack by air force. Well! you bomb the enemy land or dog fight with the enemy air force, then what? Navy, army, air force, all have different uses. **Navy is used when** * enemy can be reached by sea. * enemy is also fighting with navy and you want to destroy it. * enemy's strategic places are close to the coast and can be attacked by ships. **Army is used when** * enemy can be reached easily by land. * you want to capture and control the enemy's land. **Air force is used when** * enemy's strategic places are away from the coast. * enemy cannot be reached easily by land because of large distance, mountain, sea, thick forests, marshy land, rivers etc. * you only want to destroy enemy's places but you don't want to capture or control enemy's land initially until the enemy becomes very weak and unable to fight when army reaches. **REMEMBER** * Many people think that army and navy are becoming obsolete. But you cannot capture and control the land without army (unless you throw enough nuclear weapons so that there are no people left and the land becomes useless). You need navy to save your coastal cities, sea trade routs and ports. * If your borders are common with or close to the enemy, you will need army at some stage. Only air force may not be enough. * If the enemy's land is flat or desert, air force and later on army is effective e.g. Iraq. * If the enemy's land is full of mountain, sea, thick forests, marshy land, rivers etc., then air force can destroy enemy's places and kill many people but capturing and controlling the land is very difficult e.g. Vietnam, Afghanistan. [Answer] # The Problem You want air force to be the main solution to warfare in your world, and want a realistic, believable reason for it to be that solution. You want army and navy to exist, but be severely overshadowed by the aviation forces of the major factions in your world. ## The Desires ##### The Navy These forces generally want * Easy access to vital targets via waterways. * Clear line of sight on enemy vessels. * Waters relatively free of aquatic enemies (more important the earlier in history you go) (Giant squids, Krakens, etc.) * Large areas of water to traverse to get to a location * Natural propellant (Wind, Tides, etc.) for early ships ##### The Army These forces generally want * Easily forage-able land, and should that not be the case * Easily defend-able supply lines. * Flat expanses of ground that can be covered easily * Clear line of sight on enemy forces (flat ground good) * Cover from line of sight of enemy forces (flat ground bad) (funny how that works) * Safety from hit-and-run tactics (boats, air, etc) (away from coasts, under trees) * Land route to target ##### The Aviation Force These forces generally want * Easily traverse-able airways (low turbulence, few obstacles) * Cover from anti-air technology (could be as simple as clouds, depending on tech level) * Clear targets * Large distance / difficult terrain to cover ## Taking What They Hold Dear ##### The Navy * Perhaps your world was once an ocean world, but some event led to the sea level on your world suddenly dropping by a large margin. [![Sea Shelf Diagram](https://i.stack.imgur.com/JTd2u.png)](https://i.stack.imgur.com/JTd2u.png) If your oceans dropped by ~1,000 meters, you'd be looking at 800 meter tall cliffs on most continents, and that is terribly sub-optimal for navy forces. * Foggy waters. If your world's oceans and rivers are constantly shrouded in fog, navy would become great for small stealth operations, but would rarely be used for large-scale war operations. This, of course, inhibits your ability to have aircraft carriers, as well, as it's much harder to land on things you can't see, but it allows for secret refueling stations left out in the sea, perhaps broadcasting on a certain frequency to alert allied planes to its presence. * Squids, Krakens, and Monsters Galore! The simple addition of terrors of the deep are certain to keep early tech levels off the seas, or at the very least extremely cautious and afraid for their journeys through the waters. * Oops! No water! No water? No Navy. Simple as that. Although this option is bland in my opinion, it *is* a possible option. * The gods hate us. The natural forces that be are always forcing ships back in towards land. This is hard to pull off in a way that feels natural, but something you could keep in mind is that early ships relied on wind to go far. If the wind was constantly pushing you into land, you'd have to wait until a new invention (engines) was made in order to go anywhere close to as far with ships. Or row. ##### The Army * Deserts. They suck to attack, unless you're already used to them. Unrelentingly hot, deserts require you to drink way more water, and are flat open ground that is great for defenders to see you in. Supply lines are made difficult by soft sand, and weapons and vehicles can easily be gunked up by that same sand. * Mountains. They're hard to traverse for ground units. Unless you travel the peaks of mountains, someone can always attack you from above, and travelling at the peaks takes more time and energy. Even a mountain range between territories is a huge deterrent to land forces. * Oceans. Most people can't walk on them. Put them between territories, and voila! A huge deterrence against land invasion is born. ## Strengthen Your Air Power * **It's okay to have paratroops.** Armies are vital in taking and holding cities, and large planes with great defense and fuel capacity to support carrying many troops is a necessity if your world is mainly based around planes. * **Bombers.** This step is usually done before sending in the ground forces, but after defeating any fighter aircraft in the area. These guys are slow and powerful. They have high fuel capacity and an even higher weight capacity. They drop bombs on your target location, 'softening' the target, so that when your troops arrive, they meet minimal resistance. If everyone lives underground on your world, these planes become near-useless, as causing damage to empty ground doesn't do much to the enemy. * **Fighters.** These planes will be small, light, and fast with air-to-air combat in mind. These will be your fastest planes, and your planes most likely to go down. With that in mind, the pilots flying these planes will be the most skilled, and they will have the best protections in place for escaping the plane alive should the plane lose function. They do, however, have low fuel capacity, so they won't be going very far without help. These kinds of planes love cover. Especially once you start getting into laser-guided and heat-seeking missiles, having a mountain to dodge behind can mean life or death for the pilots of these guys. * **Mid-flight Refueling.** The smaller and faster the plane, the lower the fuel capacity. If you have small fighter planes, they will *need* somewhere to refuel. This could be on the ground for defenders, or on aircraft carriers or mid-air refueling for attackers. If you choose to go the mid-flight refueling route, you'll need aircraft specialized for the task, and they'll need to stay away from the air-to-air fighting. * **Carriers.** If it's possible to land on them, carriers are essential to attacking overseas. Even the most gassy of planes can be on fumes after crossing the Pacific. It's unwise to attack a target from the air if you lack the ability to stay there. So you'll want some way to get your planes across the expanse or refuel them once there, and a carrier fills both of these roles. If your planet has oceans, these are a great idea. * **Reconnaissance.** These will be your most stealthy planes. The ones with cutting-edge tech to keep them quiet and unseen. These will go out long before your attack commences to set up likely targets, and mark down enemy defenses. If your planet doesn't have clouds of some kind, these planes will be virtually non-existent in earlier tech levels, and very difficult to pull off in later ones. [Answer] **[Storm Hawks](https://en.wikipedia.org/wiki/Storm_Hawks)** [![enter image description here](https://i.stack.imgur.com/AfEw7.jpg)](https://i.stack.imgur.com/AfEw7.jpg) Storm Hawks is a cartoon about crystals and dogfights and maybe friendship and believing in yourself too. The real Storm was the one inside us the whole time. They have their world set up to explain why there is so much zipping around in little airplanes and also lazer-swordfights to keep things PG. > > Storm Hawks is set on a fictional world called Atmos, a largely mountainous world consisting of scattered, towering, plateau-like land masses known as terras. > > > [![enter image description here](https://i.stack.imgur.com/JgZnM.png)](https://i.stack.imgur.com/JgZnM.png) [![enter image description here](https://i.stack.imgur.com/3xFVw.png)](https://i.stack.imgur.com/3xFVw.png) [![enter image description here](https://i.stack.imgur.com/UVw5Y.png)](https://i.stack.imgur.com/UVw5Y.png) > > Directly below the terras lie the Wastelands, the most dangerous area of Atmos, with infernal fires and wicked creatures. Because of the geography, travel is mostly dependent on flight. > > > [Answer] What about a world with almost no land and the ocean is a very dangerous place. Maybe the depths are inhabited by terrible and indestructible leviathans or a savage race of deep ones that love the taste of human flesh, creatures so vicious that humans have to build floating cities sustained by zeppelins in order to survive. Maybe the atmosphere is so dense that any child can be a aeronautical engineer (because flying will be pretty easy) and some crazy airplane designs are completely possible. Well, if more ideias come to mind, I will be back here editing it. **EDIT:** apparently, denser atmospheres make the air in lower regions toxic for some reason, so I think it makes any terrain dangerous enough. [Answer] An increased importance of aircraft could become likely on a world with limited metal deposits. Naval vessels are among the heaviest vehicles on the planet. The lightest tanks are as heavy as a fighter jet. If there was a limited supply of iron, aluminum, titanium, and other metals, their use for war machines would likely be restricted to those which give the biggest bang for their buck. As fighter/bomber planes can sink a naval ship, there is the risk of losing a significant metal investment should planes attack a naval ship. Tanks are also at risk of destruction from aircraft. The term “tank plinking” came into being during the Gulf War for pilots using precision munitions to destroy enemy tanks and armored personnel carriers. The best way to increase the survivability of a tank is to add more armor. That is not really an option on a planet with limited metal reserves. They should be able to make 4-5 jets for the metal cost of a single large tank. It makes more sense to make hundreds of planes at the same cost of a few dozen tanks. Other side effects of such a world would be the use of extensive public transportation in leu of private transportation. Vehicle metal would be limited to the engines and supporting components, while the frames would be fiberglass and other lighter non-metallic materials. Cities would be built close together to prevent urban sprawl and decrease infrastructure costs. It costs significantly less metal to build an apartment building which can house 100 people than to build houses capable of housing that same number. There would be greater reliance on plastics, wood, and other alternatives. Even things like sign posts would be made from wood instead of steel. Alternatively, you could have an advancement of automation (3d-printing) which enables the rapid production of things such as aircraft, but struggles with heavier vehicles such as tanks. If your nations can produce 100 fighter planes in the time it takes to make a single tank, there would be little reason not to use planes over tanks. Just say that your automation cannot produce metals over a certain thickness, as planes use thin sheet metal it is not an issue. Over time, this use of aircraft could become a cultural preference. Of course, this type of efficient production would have a ripple effect throughout your world. Production of most goods would become easy enough to reduce the bottleneck of supply and demand. Perhaps this is how your nations gained equal status. Once a nation adopts the widespread use of this automation, they quickly attain status on par with the rest of the nations. As a nation starts to expect rapid production of goods, the idea of waiting significantly longer for something like a tank becomes less workable. If replacement times are measured in months as opposed to days, it becomes harder to argue for that option. Alternatively, you could have an Einstein type character who designs a “perfect” aircraft and releases it to the world in the hope of preventing wars (or whatever other motivation fits your narrative). This is what the Expanse novels did for their Epstein drive. The use of these super aircraft turns the tide of battle so drastically that all nations prioritize their use. This does not have to be a specific aircraft, but could be an AI control system or something else which makes planes significantly better on a battlefield. As the battlefield losses against these aircraft increase, the only option is to copy that design. Continuing to field tanks which are nearly instantly destroyed would cause public backlash. This happened during the Iraq/Afghanistan wars when unarmored Humvees and other vehicles were easily destroyed by the local forces. It resulted in several completely new lines of vehicles to combat the threat. Eventually, your nations would adopt the new aircraft out of necessity. A super airplane would have the least impact on the other aspects of your world. [Answer] You want to give as much advantage to aircraft and as little to the ground/navy forces. That means: * large flat terrain with little to hide in for easy spotting and detecting. * large pieces of cover that hide aircraft approaches and make it easy to pinpoint potential radar sites and reach them. This means that many singular mountains or hills are present with only a few kilometers of flat terrain distance. * no easy supply routes for ground armies. That means many bridges or roads that can only be constructed in specific area's making it easy to cut off. Swamp lands for example. * little deep enough water with enough connections to other bodies of water. If the navy is stuck at say Vietnam types of water area's then the navy can only use small boats. This would mean that the best methods of attack would be scouts that radio in enemy ground/navy forces or supply lines which then see strikes from helicopters and aircraft that use the few large (and devoid of meaningful vegetation) pieces if cover to approach their target. The defender's best option is to use MANPAD's for the lowest flying units and station vehicular missile systems behind or on the sides of the mountains and hills. The second most used unit would be artillery due to its range, but its also a very supply hungry unit\*. Aircraft are hungry too but land far behind their own lines where supply lines are easier to maintain. Something else to consider: airships. While some highly public crashes made airships look like they were slow and made of explodium, the truth is that they are the toughest aircraft to have ever existed. In fact jet engine aircraft were in the same spot at some point where people thought they were more expensive, more fuel consuming and more dangerous alternatives to prop aircraft that just kept randomly crashing despite being young planes. They found out that it was the lack of rounded edges on windows that caused the planes to crash due to stress failures. Airships, properly build and with the same decades of design as modern aircraft behind it, would be a magnitude tougher than the toughest modern military aircraft. Multiple lifting gas bladders, not using highly flammable materials for the outer skin, superior construction materials, modern weather and electronics for safety and detection of leaks, heavier-than-air airship designs and higher redundancy than planes would all help make these excellent additions to modern air power. A simple example: airships would be far superior to modern early warning aircraft like ELINT or AWACS due to the larger and more powerful versions an airship could install and the ability to be on-station for LITERAL DAYS compared to several hours (and even in WWII airships could fly across the atlantic and back in one go without in-air refueling). Additionally the ability to use offset armor plates to detonate incoming missiles prematurely and catch shrapnel with spaced armor designs would help protect vital area's (on top of again redundancies). Having another airship as a missile barge would also supplement your airpower ability, as missiles fired from it dont have to climb as high to intercept their targets, meaning more fuel for speed and chasing for a larger effective range. \*I think Russia's current supply lines are for 50% dedicated at feeding their artillery in some way (ammunition, fuel, food, maintenance along with the consequences of all the maintenance and fuel required to maintain a supply line to the constantly moving artillery pieces). [Answer] **Increase air pressure** If the air would be more dense, nature would grow stuff that floats, and with stronger winds there would be stronger skin and stuff (to a degree) that would allow even early craftsmen to attempt floating, or making deltaplanes or similar contraptions to quickly cover ground while descending. The atmosphere contents as well as biology could be slightly altered to avoid broken physics or biochemistry, say humans could develop protection from decompression issues raising from them travelling heights, without actually changing appearance of lifeforms, except those that specifically take advantage of dense air and are impossible on Earth. The very same alteration could as well harden sea travel, because sail-based ships might not cope with more harsh weather in deep sea, and with advent of fossil fuels and combustion, using hot air to lift up zeppelins might even be energetically cheaper than making a sturdy ship capable of sustaining high winds and propel it with diesel. **Use Pangaea** Employ a scenario where the sea is too far for involved parties to ever take part in the story, except maybe as a place to refuge or seek death. Everything else should be either land or air, and air travel is by definition faster than land. [Answer] # Post Apocalyptic wastes: Your terrain was once verdant farmland, forests and lush countryside. No more. Once great natIons are now limited to bunkers, isolated valleys and islands. Vast regions are filled with radiation, deserts, mutants, and lingering super anthrax. The seas are poison are filled with mutant monsters. Drone AI nuclear submarines operate autonomously attacking ships like a cross between Moby Dick and the Nautilus, still fighting a long-lost war. Many nations prepared for the apocalypse, building up aviation industries around aIr bases. Their best and brightest were saved to rebuild civilization. Advanced automated factories churn out advanced equipment as fast as resources can be found. But the remaining bases are isolated and far apart. They scavenge the wastes with blimps and dirigibles, retrieving supplies and equipment to rebuild. The new distribution of resources and power looks quite different than it did. Battered superpowers scrabble to hold on to vast territorial claims. New powers that came through the war less damaged refuse to recognize outdated maps. The table is set for a world where air power rules, fighting at vast distances in a world where armies dare not travel and every port has been destroyed. [Answer] **Who cares about ships... Just build a plane!** Alternative option here: Earth like planet with different gasses and main element compunds. In this world, lets say there are easy to make mixtures creating "lighter than air" liquids and/or gasses. Add some certain metals with less weight, extreme flexibility and they are easy to manufacture. Aerial combat is effective in our world as it is. One of the problems with air attacks is, well, building a good plane or airship is hard. Engineering when it comes to planes, needs to be deadly precise. And even then there are accidents. But what if... There are easily accessable good materials to build planes cheaper, more efficient. If hindenburg accident didn't happen, or if people had access to large amounts of safe light gasses for airships, they wouldn't be so rare as they are now. If building and maintaining a plane or air ships would be this easy, I wouldn't spend most of the budget on land or sea based weaponary. Mostly aircraft carriers, land based portable aircraft launchers for faster take-off, and enough fuels. This way, most of the combat would continue on air, and other units would mostly support air units. Because, why spend money on building a good ship when you can build 30 nice planes. With half the price and material. War is a battle of information, resources, morale and economics. If one method offers significant advantage on even one of these, then people would naturally choose that more frequently. ]
[Question] [ I have a fantasy setting where groups of characters, let's call this groups "guilds", compete to gain the favor of the king by doing missions for him. I wonder if there is a plausible reason that can be used to explain why this groups rarely go past the 8 members or so. What I could come up with is that the world could be lacking resources, still, it would make more sense to band more people together to be stronger, imo. I am also unsure about using the term "guilds" to identify such groups. Thank you edit: I will wait a few hours in case of a better answer, as of now @Nepene Nep gave me something I feel like I can work with. [Answer] ## Betrayal is routine. The missions generally involve extremely fungible resources like rare ores, or exotic magical materials that are easily carried away by people. As such, if you have too many people involved it's common for the others to either steal the resources or warn another group so they can take the resource after the first group defeats all the enemies guarding it. Small groups are optimal for minimizing the risk of betrayal. [Answer] Based on my experience with complex organization, the size of a team which can be effectively managed by a single person is about 10 individuals. More than that and you need to start adding intermediate layers. Translating this in your world it means that the chief/manager of the guild would need to add subchiefs/intermediate managers to effectively manage the guild. But, since they are competing for the king's favor, it increases the chances of betrayal. Therefore what happens is that larger guilds do exists, but not for long times: they soon break up in a fight for power. [Answer] The reward for the completion of each mission is fixed, not per member or per hour, so every person who joins the group reduces the final payout for each member in the event of success. Adding more people to a group can increase the odds of success or the speed of completion, but only up to a point. Adding more people can do things like expand the versatility of a group, increase its ability to perform manual labor, and improve their rate of success in combat, but things like travel cannot be sped up by adding more people (and in the case of travel time, since you travel at the speed of your slowest party member, adding more people could slow you down), and tasks that can only be performed by certain experts within the group are not sped up by having a larger audience. You can think of this in terms of marginal utility. Starting with one person, each person you add to the group increases the expected returns for each member (the rate of success multiplied by the expected reward, but divided by the number of members), but by slightly less than the person before, until (at around 8 people at most in this case, but varying depending on the group) the expected returns start to decline. Put another way, one person, if they could complete the mission solo, would be able to take the entire reward for themselves, however they would be very unlikely to succeed on their own so the expected rate of return would be low (and the rate of mortality would probably be high). Give them a partner and now their potential reward is halved, but they are much more than twice as likely to succeed, so overall this benefits both of them. Add a third member and now each gets a third of the payout, but again their odds of success increase by more than enough to compensate for the decline in the size of each payout. However, at some point (which will vary for each group, and in your scenario seldom goes beyond 8 people) adding a new member will not increase the chance of success by enough to justify the reduction in the size of each payout. Groups may even "feel" this out for themselves, with success attracting new members until the old members realize they aren't making as much as they used to, and leave the group for other, more profitable groups, until those groups get too large and the cycle repeats. [Answer] Many kingdoms are setup in a sort of Fiefdom with other rulers under the king. This kingdom in particular has had a rocky past with lords and ladies assembling standing armies that have tried to overthrow the king. So, the wise people got together and decided that any group numbering over 8 people would be considered an army and no lord may keep a standing army. The king still maintains an army, but he can't send them around fulfilling missions without making the lords and ladies nervous that they have somehow run afoul of the king. Groups of adventurers rose to the occasion to fill this niche. Their services are often called on by the lords and ladies, who can hire their services without drawing the watchful eye of the king. These groups are often at odds with each other since those in power are generally repeat customers, only dealing directly with the groups leader and relying on the groups continued discretion. It has been rumored that the king has appointed particularly successful group leaders as lords and ladies, resulting in most groups trying to build up their own name with the hope that they too can rise in class. There have been times when several of these groups have worked together to accomplish an especially difficult goal, but without the king's direct oversight they were quickly viewed as an invading force and had the kings army dispatched to disband the group. [Answer] adding more doesnt necessarily mean it done faster or better, if what i understand right, considering the typical fantasy D&D kind of mission or RPG in general, the task/mission given is likely something like exploring dungeon or cave, or being a courier or messenger, or something shady like stealing some artifact/precious items to assassinate someone, or capturing someone that cant be touched by laws or the king force due to political consequence of it or something like that. that kind of task is more suitable for small number where subterfuge/secrecy or the environment require so, otherwise you can end up wasting precious time in completing the mission, like the problem to provide provision to the team in the mission, too many and you likely need wagon or animal of burden to carry it not consider the time require to travel will likely be slower due to the number and that cost time. more problem with team member drama, more harder in helping the members trouble during the mission, for example one of them goes missing or stuck in the dungeon due to the high number or the healing treatment needed. since you say this is for king favour i doubt they get paid or at least their provisions is paid by the king so your main focus is to do the job/mission faster and better to gain the king favour, but if it not then you need to consider the income and outcome of the team too, otherwise you likely get outcompete by smaller and experienced group in that field, basically you need quality over quantity. [Answer] The king said so. If the groups are vying for the favour of their overlord they have to play by his rules, if he makes it widely known that he doesn't think the larger guilds are really trying or that he considers them beneath his notice then smaller groups are going to be the norm. Yes it would make sense for guilds to be much larger and incorporate more specialist craftsmen etc... but the king's patronage pays less of the bills with every member added. This results in guilds being so large they are slef contained and quite small and hiring a lot of their work done by outside specialists and very little in between.It doesn't necessarily stop informal groups of guilds banding together through mutual aid pacts as long as nothing is made official and they can conduct business privately. They're guilds if the king says they're guilds, a fact that is probably worth mentioning within the narrative, yes it's odd, yes Empire X has guilds numbering in the hundreds but here a guild is no more than 7 or 8 strong, by royal prerogative. [Answer] The missions are not such that you can solve them by throwing more and more bodies at them. In fact, the larger the group, the more likely that it will attract attention. The only real use of a large force would be to distract from the actual team that goes and does the thing during the time of the distraction, and that only works if the thing distracted is not clever enough to deduce that it has to be a distraction. Additionally, the people who can actually carry out the task are few and far between. You can not pick a complex lock by throwing thirty locksmiths at it. You can not defend a corridor against a swarm of goblins (which dissolve on death, letting more in) with a dozen warriors who would not have room to swing their swords. You need highly skilled people, and a small team of those is hard enough. [Answer] Building on @LDutch answer: It is all about Team Leading and profit. Given that the team that may be efficiently managed by a single person may consist of no more than 10 individuals, this means that adding more people, as LDutch pointed out, means adding some intermediate management. This, in turn, means that the expected profit of that additional manager will be higher than of the "rank&file", thus the growth of rewards for larger task (that the 8 member group is unable to complete) needs to be larger than linear growth (otherwise you loose money), but it is not. Moreover, most of the tasks are small enough that a group of 8 people is capable of fulfilling them. Additionally number 8 may have some religious, magical or mystical connotations, especially in that line of work. And when a big and lucrative task presents itself multiple groups may cooperate in a join venue in order to complete that one task and then each groups goes its own way. I hope that you will find some of those ideas helpful. [Answer] In addition to others' answers mentioning division of reward with more members in a group, another plausible reason can be - **requirement of highly specialized skills**. Some people possess theses skills inherently (can be hereditary too). For those who do not possess these skills, it would require a long time of training by existing group members, something not feasible for the group to do. Any single group (of 8) may be formed by members of the same 3 or 4 families through many generations. This would be consistent with the restriction of the skill being inherited only by those few particular families' members. So the group size is limited to 8. Even if there are >8 family members with the skills, the group size is limited by mutual consent to 8 (say 8 eldest members between ages 20 to 45) to accomplish the required secrecy. Such mutual consent by a fixed rule is easier to achieve within a family. When someone in the group is injured or becomes too aged, he/she is replaced by the next in their family. Additionally, it can be reasonably expected that the degree of trust is higher (reducing chances of betrayal) amongst families that have been long-standing allies. You can even introduce a rare event where an outsider enters the group after extensive training by someone who has the skill but hasn't joined the group yet. This admission of non-family members, however, is highly discouraged by the societal norms or the king's guidelines to the group, so isn't a regular occurrence. [Answer] Broadly no, there is not a plausible reason that could explain why your groups rarely go past eight members. How could your world lacking resources matter? In many situations it would indeed make sense to band together, and so what? ]
[Question] [ For various reasons I have an army that uses many smaller vehicles instead of spending a lot of full main battle tanks. This army uses mostly up to 90mm\* cannons on their vehicles rather than the massive 120mm+ cannons that adorn most MBTs today. If you shoot a 90mm cannon against something like the front of an Abrams tank you can practically fire one all day and not punch through the armor. To combat this my army has developed a simultaneous hit method, allowing multiple vehicles to hit the same target and overcome its armor. The question is, does this work and how well would it work? There's 4 parameters that I can see: * The grouping of the shot. If they hit a meter away from each other they'll do less damage then if the shells are practically touching each other when they hit the armor. * The timing of the shot. If they hit simultaneously they'll likely do more damage than if they hit with 0.1 second between hits. * The scalability of shots hitting simultaneously around a spot. 2 shots will deal less damage then 3 etc. * Hitting in tandem instead. Hitting the exact same spot, meaning that as one shell explodes the next one is almost hitting it as well. Please note that the implications of the accuracy or situation in which this can happen is not part of this question, just the implications of simultaneous hits **\*** Subject to change if necessary to something smaller or larger. The main point is that the cannon isn't able to significantly damage the armor it's firing at in single shots. [Answer] Sounds like a weirdly roundabout way of making a [tandem warhead](https://en.wikipedia.org/wiki/Tandem-charge). [![Spike antitank missile diagram](https://i.stack.imgur.com/0N136.png)](https://i.stack.imgur.com/0N136.png) This is apparently a [Spike antitank missile](https://www.army-technology.com/projects/gill/), which uses such a tandem charge. In real life, this is done to evade [reactive armour](https://en.wikipedia.org/wiki/Reactive_armour), specifically the explosive kind, and isn't so good against other kinds. > > The grouping of the shot. If they hit a meter away from each other they'll do less damage then if the shells are practically touching each other when they hit the armor. > > > Most likely, if they can't penetrate the armour then they'll do nothing, not just "less". Grinding down the target is something that works well in computer games, but less so in real life. Light tanks should try to flank tougher opponents, hit them in the weak spots or just disable them rather than trying to blast their way through the main armour. > > The timing of the shot. If they hit simultaneously they'll likely do more damage > than if they hit with 0.1 second between hits. > > > Depends on the kind of shell, but explosive rounds going off at *almost* the same time right next to each other risk having one disrupt the other and limit its effectiveness. Two armour penetrating rounds can't usefully do much hitting next to each other (cos you'll make a wider hole, not a deeper one) and there's no guarantee that hitting in the exact same spot one after another will dig a deeper hole either. > > The scalability of shots hitting simultaneously around a spot. 2 shots will deal less damage then 3 etc. > > > It is also a lot less likely, right? If you need to plan for that sort of occurrence, it seems like you've already shown that your tactics and weapons are terrible, and one or other has to change. > > Hitting in tandem instead. Hitting the exact same spot, meaning that as one shell explodes the next one is almost hitting it as well. > > > ...and so you've reinvented the tandem charge warhead, but in a really awkward way that requires microsecond precision from chemical powered guns with human manufacturing tolerances probably being fired from a bumpy platform by stressed crew. But at least you know that the basic idea is sound, and has been tested in the real world ;-) [Answer] In principle it can work, practically speaking it is highly unlikely. Energy wise, when the shell hits the target, its kinetic energy is transferred to it. Same happens with the additional energy of the explosion, if the shell is explosive. What happens next? If the kinetic energy is higher than what the target can take in the area interested by impact, the target will be damaged. If instead the energy is not sufficient to break the physical continuity of the target, that energy will be converted into heat. That heat will be then dissipated to the surrounding environment by the usual transfer mechanisms. This is similar to what happens if you hammer a piece of metal: it will heat up. If the fire cadence in a specific area is high enough to prevent it from dissipating the heat, it will eventually reach a temperature where it will become more plastic and yield to the impactor. However you need to consistently hit always the same spot with a very high cadence, that's why it highly unlikely. [Answer] Your concept has already been trialled in the [RDF/LT prototype light tank program](https://www.militaryfactory.com/armor/detail.asp?armor_id=655). However, it differs from your premise in that this is a single vehicle intended to inflict multiple near-simultaneous hits on the "same" spot of a target vehicle. For **multiple** ground vehicles to even attempt this would likely require a form of networked computing to synchronise their shots. This in turn brings up the issue of electronic countermeasures, a thing which already exists in the real world. Effective ECM jamming would immediately cause your concept to fall apart. Even when it doesn't, it would require your multiple light vehicles to all engage one target from a similar angle, which runs counter to real life military doctrine and general good sense. In short, the concept as originally presented is too impractical to work against an actual enemy. Starfish has the right idea. PS: There is a platform where your idea has sort of been implemented though: the [A-10's GAU-8 gatling gun, the one the entire plane is developed around](https://en.wikipedia.org/wiki/GAU-8_Avenger). What doesn't work for ground vehicle(s) can work just fine on a single dedicated ground attack aircraft. [Answer] There is Soviet Union Anti-Aircraft system called [Shilka](https://en.wikipedia.org/wiki/ZSU-23-4_Shilka). I have heard stories that it can, using it 4 23 mm rapid fire autocannons, damage not only aircrafts, but fortifications and even dated tanks. As they say in wiki > > Despite its present obsolescence as a modern short-range anti-aircraft > weapon, the ZSU-23-4 is still deadly for enemy light armoured > vehicles, infantry and firing points as an infantry-support vehicle. > With its high rate of accurate fire, the ZSU-23-4 can even neutralize > tanks by destroying their gun sights, radio antennas, or other > vulnerable parts. > > > So, if we have modern tank caught by cross fire of few Shilkas, its armor will probably survive, but we cannot say the same about crew inside or other onboard machinery (targeting systems, motivators, tracks, engines air intakes, anthenas, etc...). Probably, tank ammunition can detonate inside it. Most likely crew will be shocked by loud sounds of `Shilka` ammunition damaging armor of tank, and likely to be hit by pieces of tank armour, that falls appart fron internal layer, when external layer of armour is deformed. UPD: continuous exposure for "Shilka"'s fire sooner or later can damage even frontal armor of modern tank (lets say, it can survive ~ 1-2 minutes under fire), but tank still have good chances to fight back and score "Shilka" - it has quite basic armor. But things can be changes if there is ambush of few "Shilkas" against tank. [Answer] **Explosion from first shell could damage second.** First some assumptions. We are talking about (from OP) > > Hitting in tandem instead. Hitting the exact same spot, meaning that > as one shell explodes the next one is almost hitting it as well. > > > You observe that hitting the tank twice a meter apart at the same time offers no special benefits. Two shells hitting the exact same spot at the same time is not possible because these are not phantom shells - each occupies space. So the best you can do if you are hitting the same exact spot is to hit it twice in rapid succession. You risk interfering with the second shell because of the explosion of the first. Shells can be deflected by explosion. There is armor that does this. <https://en.wikipedia.org/wiki/Reactive_armour#Explosive_reactive_armour> The explosion of the armor disrupts the energy of the incoming projectile by various means depending on the type of projectile - changing its trajectory, wasting some of its explosive power and so on. If your second shot is tailgating your first it will run headlong into fast moving shrapnel and armor pieces produced by the explosion of the first. This will slow it down if nothing else. More seriously a hit on the incoming projectile could cause it to turn and so hit the tank sideways or at an angle, not with its hardened nose. At worse the explosion damages the second shell such that it does not detonate. --- I forsee that the solution to a first shell interfering with a second is some delay. Hit the same spot of armor some time after it has been hit but the first shell. This may be a few seconds later. Or a few days later would work equally well. I suspect that for as long as people have been launching assaults on armored targets they have hoped for a second hit on armor weakened by some prior first hit. It is a good strategy and one you can use for your fiction! [Answer] > > ...isn’t able to damage the armor it’s firing at in single shots. > > > There’s a very easy solution to this that does not involve complicated fire-control disciplines: ## Don’t aim for the armor. Tanks in general, not just modern MBTs, have a *lot* of weak points that if hit will put them at least temporarily out of commission. In the rare cases of modern tank-versus-tank combat (which, in reality, hasn’t really been much of a thing since the end of WWII, tanks are usually fighting infantry, troop carriers, or emplacements, not other tanks or tank equivalents), they just aim for destruction of the vehicle as a whole because it’s both possible and more efficient, but there’s no rule that says you have to do that. The tracks and suspension are the most obvious example such a weak point, and even just a well placed shot with a 30mm machine gun is enough to stop a tank if you aim for the tracks and suspension. Other favorite targets include the gun sights, the turret ring, the mounting of the gun mantlet, any external fuel tanks (these are a thing even in some ‘modern’ designs, and tend to be less well armored than the rest of the vehicle), and of course the commander if he’s stupid enough to stick his head out. The goal here isn’t to destroy the enemy tank, it’s to make it impossible for it to fight effectively so you can either flank it and shoot weaker armored areas, or just swarm it with infantry (both, if pulled off correctly, will ruin the unlucky tank crew’s day). To put this differently, I encourage you to find and talk to people who play games like World of Tanks or War Thunder. Neither game is super realistic, but both get a handful of things right, and one of those is that if you’re a light vehicle fighting something you can’t punch through the armor of, the most effective option is to incapacitate it to give your friendly artillery (or bombers, or heavy infantry, or Panzerkampfswagen VIII Maus) an easy target. Overall, this approach means that your materiel doctrine needs to favor accuracy over stopping power, which is actually a legitimate reason to some extent to want smaller caliber weapons *if* you do not have access to things like modern [APFSDS](https://en.wikipedia.org/wiki/Armour-piercing_fin-stabilized_discarding_sabot) rounds. Depending on your exact choice of munitions, you may not even want smoothbore guns like most MBTs use. [Answer] Simultaneous hits on an armored vehicle will produce different result based on the technologies involved, and your fictitious generals will need to understand this and change attack doctrine appropriately. Against homogeneous (such as cold-rolled steel) armor that is relatively flat (not sloped) compared to your firing angle, simultaneous hits will not make a noticeable difference over a single round hitting. The goal of an AP round is to deform the armor material to breach it. Any round that individually cannot deform the armor material will likely need closer to an order of magnitude increase in stopping power to be able to penetrate said armor. Using HE rounds (or rounds such as squash-head rounds) come to the same conclusion with a caveat. If a round would cause spalling (internal fragmentation of the armor due to external impact), multiple simultaneous hits would cause proportionately more damage. This can mean the difference between occasionally disabling enemy armor, and reliably doing so. Again though, if 1 round is ineffective, piling more on is not a feasible solution because of how armor works. Things change if ERA (explosive-reactive Armor) is present, or similar technologies. In the case of ERA, tandem charges can be (most likely poorly) simulated, allowing for the first round to be sacrificed to trigger the armor, which weakens it for the second round to penetrate. Now that the question is answered as asked, I would point out that your simultaneous hit strategy would be much more effective if your generals started by de-tracking or otherwise immobilizing the enemy armor before planning the firing solution. [Answer] if you want to use 90mm shells instead of 120mm ones, then here are some options. Don't rely on kinetic energy to do the damage. 1. Instead fill the shells with an acid that is incredibly corrosive to steel. As you hit the tank over and over, you will eventually melt through the armor. 2. Make a "sticky" round filled with thermite. It hits the tank, sticks to the armour, and then releases so much heat the armor melts. [Answer] ## Could work, but needs absurdly high accuracy Modern tanks (including all versions of the Abrams) use metal/ceramic composite armour, and contrary to what other answers say the ceramic component of this does make it highly susceptible to multiple hits on the same plate due to the ceramic shattering. However, because of this (and other reasons of practicality) plates are made as small as possible ([wikipedia claims around 4"/10 cm diameter](https://en.wikipedia.org/wiki/Chobham_armour#Structure)). Reliably being able to make multiple hits within such a small area at tank combat ranges of 1km+ is implausible without some kind of magic active guidance for the shells, in reality even the most modern tanks don't do more than aim for centre mass. Tanks firing at tanks also now primarily use APFSDS kinetic energy penetrators, which do not carry explosives to the target (with the almost-exception of depleted uranium being pyrophoric in powder form). To address your points: * The grouping of the shot. If they hit a meter away from each other they'll do less damage then if the shells are practically touching each other when they hit the armor. As stated, they need to hit the same plate, that's the only real criterion * The timing of the shot. If they hit simultaneously they'll likely do more damage than if they hit with 0.1 second between hits. I'm not sure that two shots could practically hit "simultaneously" enough for it to matter. It would have to be on the same plate faster than the speed of sound in the armour carries the ceramic shattering, which is going to be much faster than a millisecond. Either way, you want the ceramic to shatter before the next shot hits so if anything this would be detrimental. * The scalability of shots hitting simultaneously around a spot. 2 shots will deal less damage then 3 etc. After the armour is degraded your shots should penetrate into the crew compartment. Most likely one penetrating shot will do the job. * Hitting in tandem instead. Hitting the exact same spot, meaning that as one shell explodes the next one is almost hitting it as well. I don't see any advantage here either, other than maybe being more likely to hit the same plate on a moving target. ]
[Question] [ Mana is the life force of the human soul, which allows us to function as we do. As a person gets older, their mana supply increases, which makes them potentially stronger in the use of magic. However, after a certain point, physical age becomes a barrier to how much of it they can actually access. Because their bodies get weaker with time, they are unable to use their mana stock as efficiently without cost to themselves. Trafficking is a problem in this world. There is an underground network of witch doctors trafficking in humans for the purpose of using them for spells. After a person is killed, their body is dismembered, with specific parts grounded up into powder to use as ingredients.These are called muti-killings, in which an individual is murdered in order to power a ritual to granting certain benefits to a customer, such as luck, power, love, etc. As stated, a person's mana supply increases with age, but they don't benefit from this after a certain point. Therefore, it would be logical to use older people, specifically the elderly, for these kinds of spells. However, the group always used for these rituals are children, which are targeted specifically for these kinds of crimes. Why would the mana of a younger person be more useful for these kinds of rituals? [Answer] ## The strength of someone's mana is determined by how much experience they have My idea here is that an individual's mana is shaded and molded by their experience and learning. A person's mana getting stronger as they age isn't a result of it increasing its raw power, but of the person's understanding, wisdom, knowledge, and personality growing and becoming more defined. This allows their mana to take action more efficiently and more effectively, but it makes it more difficult for someone else to direct. ## Mana only likes to be controlled by whoever made it Normally, mana only acts perfectly in accordance with its creator's will, becoming perfectly malleable to whoever it came from. However, this malleability only persists as long as that person's will exists to guide it. Should that person's mana be taken from them somehow, another person would have a much more difficult time actually directing it. Mana removed from its owner, by whatever means, has a tendency to act out. This is because mana itself almost seems to have a will. In particular, it seems to have a desire to only be directed by whoever made it - not that it's actually conscious or intelligent - and it will fight against anyone else who tries to control it. ## Age makes mana more complex As a person gains experience, their mana becomes more complex. This is a result of the mana generated incorporating an individual's experience and personality into itself - or more accurately, being generated from a more complex personality. The more complex this mana is, the more devious it is likely to be in its attempts to avoid being used. Remember that mana's complexity comes from its owner's own experience. Someone who is older has had more opportunity to gain experience, and thus their mana will generally be more complex than that of someone younger. Children, on the other hand, have virtually no experience, so their mana is incredibly simple. This limits what it is able to do, but this also makes it easier to control. In effect, it is a lower quality, but far more malleable, supply of mana. ## This makes children's mana easier to use, and thus more desirable Children's mana is technically lower quality in that it is simpler and cannot perform a task as efficiently or effectively as more complex mana. This same trait makes it easier to control and direct, as it is less capable of resisting. Now, when someone needs a ritual done, especially a complex ritual with many parts that could easily be disrupted, they want mana that they can reliably control, and therefore, they want mana harvested from children. [Answer] Mana produced by a younger person is more pure, while, with the progress of age, together with the amount produced, grows also the contamination of mana due to life experiences. Purity is a highly valuable aspect when it comes to magic rituals. Just remember how many times the blood of a virgin is requested. [Answer] Because they can't fight back. Children are young and inexperienced. True, the elderly can't use as much magic as a child, but they have vast reserves and decades of experience. There are dozens of magic systems that raw strength will get trumped by skill, because of how little power it takes to counter magic if you use the correct counter magic. For instance, a powerful fire caster could easily get defeated by judicious use of wind magic to remove oxygen from the air. I'm not saying that every old man is dangerous. But enough of them are to the point where it just isn't worth it. As Terry Pratchett's Silver Horde proves, it's a very bad idea to mess with old and wizened warriors because they have gotten extremely good at not dying over the years. [Answer] ### Mana doesn't technically become stronger with age - it becomes "stiffer", but also more attuned to the user. Everyone generates a more or less static amount of mana throughout their life. In children, however, this mana is fluid and unformed. It takes energy for a child to turn it into magic and manipulate it for useful tasks, so the end result appears weaker. But if stolen, it can be more easily processed into useful magic. As a person ages, their mana "source" becomes attuned to the mind of the user. The mana is created already formed in a way that the user can make use of it more easily, causing it to grow stronger in practice until the weakening of the body becomes an issue. However, this attunement only works for the original user. If stolen, it is *harder* to make use of since it must be "softened" by the magic thief to be reformed according to their own magic wavelength. [Answer] Energy density and volatility. Ingredients from older people might hold more power, but its harder to release it in a controlled manner over the course of the ritual. Using a lower grade source reduces the chance of failure or even catastrophic backfire. This would also hint on why older people can't use their full potential. Their subconsciousness limits them to safe levels. Overriding this causes damage. [Answer] ## It's easier to shift. The mana in a child is weaker, so just about everyone will be able to use it, whereas the target audience of old mana is extremely select and only takes up a very slim share of the market. Who wants to drag a product around for ages, looking for some unicorn of a customer, when you can have something everyone can buy? Think about books. Bestsellers are not necessarily the greatest pieces of literature; all too often they are easy-to-read books about a popular subject; bland, basic stuff everybody likes. They're not the best, but the ones with the broadest audience. [Answer] Who says it can be split? Kids could have small ammount. And the droplet of it its an unit, diminute one at that. Ideal for delicate machinery or activating runes. Now open the body of an ol' armaestre, his gut bursting with a prominent stone of condensed mana. Radioctive even, the mere prescense of it makes all the lab machinery go haywire. Even the ouija boards get out of calibration. So you are a provider and need to store the stuff, safely, along with other merchandise. Grab a tupperware and place all the tiny droplets, adipose tissue impregnated with the good stuff. Pay yer ticket and good to go. Next! [Answer] Since mana is related to human soul, I think it would be the lack of negative emotions in the extracted mana. I don't mean impurity here, but the attached emotions that affects the nature of mana itself. If you want to use mana to bring favourable outcomes like good luck, success, etc., Then a mana with positive nature would be more suitable. Children are inherently devoid of negative emotions, even if their actions are horrifying, the feelings behind those are pure. Whereas if you kill adults to extract mana, the mana will be tainted by the negative emotions from being killed, like hatred and vengeance etc. This kind of dark, violent mana is more useful for curses I would say. ]
[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/114071/edit). Closed 5 years ago. [Improve this question](/posts/114071/edit) For reasons of both balance and making each class in my videogame visually distinct from each other, magic uses tend to wear long robes, capes, and other hallmarks of wizards and witches. This often clashes with what the more physically inclined character are wearing (since they wear actual armor to avoid getting murdered by enemies) and, more importantly, civilians (who go about in whatever is appropriate to the era). I get the mechanical purpose of "squishy wizards", but I'd be happy with some reason why magic users dress differently from ordinary people. Sure you can't wear armor, but why march into battle with in what is basically a nightgown and sunhat instead of some causal wear? **How can I justify visually distinct magic users?** I'm fine with the reasons for a magic user to not wear armor, but I'm looking for any reason for magic users to dress differently from rogues and ordinary civilians. Also, the magic users' clothing need not be stereotypical wizard/witch-y (anything to set them apart would be fine), but justifications for those types of outfits would be accepted as well. Some level of adventuring/traveling practically would be appreciated, but not totally necessarily. [Answer] **Pride** Wizards, compared to other people, are basically miniature gods. They can do all kinds of things that would be otherwise impossible. The visual distinction is intentional, to show that they are different, above the rank-and-file. They practically invite attack because they are not afraid of whatever physical assault a lowly soldier might muster. **Drama** There's a degree of showmanship in wizardry - flowing robes exaggerate the movements of casting a spell. And after all, if you can call down lighting or hurl fire from your hands, aren't you probably a little bit of a show-off? **Tradition** Wizards wear robes because wizards have always worn robes. Physical warfare evolves as weapons become more powerful and armor more durable, however, magical warfare does not conform to the same conventions. No update in armor is going to be as powerful as a wizard's barrier spells. And with so much more learning to do, who has time to worry about the fashion of the day? Not wizards. **Social pressure** Maybe it's not the wizards' fault. Maybe everyone else is interested in keeping tabs on the mini-deities among them and force them to wear what we conventionally think of as "wizard clothes" so they can easily identify them. Given the overwhelming number of "normals" compared to wizards, they found it easier to cave rather than fight back - magic is not something likely to be looked at with favor throughout most of history. [Answer] If you take a really close look at most depictions of what you call nightgowns, you will see that they often have intricate patterns woven onto them. Magic usually deals with symbolisms of all kinds. The patterns on said gowns may be magic sygils. A nightgown has much more space upon which to scribe arcane markings than a T-shirt or a pair of pants. In fact, the more folds it has on the hem, the more space for enchanted writing it will have. [Answer] There's not a huge need to justify this, as it happens in real-life: First off, we have [Acedemic Dress](https://en.wikipedia.org/wiki/Academic_dress). Today that is mostly only worn around graduation ceremonies, but originally this was the typical attire at medieval universities, particularly Oxford and Cambridge. This was almost certainly the inspiration for the magic-user robes trope, and doesn't look too far off from it today. [![enter image description here](https://i.stack.imgur.com/BdMSf.jpg)](https://i.stack.imgur.com/BdMSf.jpg) I've heard people who wear this every day promote it as very practical attire for their profession, as it is very easy to just throw the robe on over whatever you happen to be wearing when you need to drop your studies to go out in public for some reason. That should of course equally apply to a typical magic user, as they also spend a great deal of their time on their studies. The colors, stoles, and patterns can perform a signaling function to other practitioners to indicate exactly to what school the wearer belongs. To everyone else, they just look very colorful and diverse. A person who wears armor will have to spend a lot of time maintaining it, while a person trying to wear normal fashion in human society has to spend time keeping on top of what is currently fashionable, and maintaining a proper wardrobe accordingly. A magic user is wholly focused on their craft, with little time for such nonsense, so the robe is both their most practical option, and a way to signal this. I'd argue the closest modern equivalent to the magic user is the computer programmer. As one myself, since 1985 when I go out in public, I don the closest modern robe equivalent: the Baja Pullover. The style for these is essentially unchanged in the intervening 30+ years. [![enter image description here](https://i.stack.imgur.com/VeyIF.jpg)](https://i.stack.imgur.com/VeyIF.jpg) Same logic applies. I don't have to keep track of fashion, don't have to worry if my shirt is stained or otherwise offensive, or even in extremes, existent. Just throw it on and go. [Answer] Why do CEO's wear expensive suits? Why does the Pope wear an [impractical hat](https://en.wikipedia.org/wiki/Mitre)? Why did French emperors wear [dainty tights and big wigs](https://en.wikipedia.org/wiki/Louis_XIV_of_France#/media/File:Louis_XIV_of_France.jpg)? Their clothes are a status symbol and sign of tradition. Magic users wear pointy hats and robes because that's what magic users wear. Armor is not worn because the magic users have always believed they are strong enough to not need it. Normal clothes are not worn because the magic users have always believed they fail to represent their status. Robes and pointy hats have always been worn because they've always been worn, and to do differently is a sign of weakness or a breaking of tradition. [Answer] Casting spells requires the appropriate gestures, and for that you cannot be slowed or hampered by an armor. Moreover, you might also want to hide some of the gestures, especially those which requires hands only movement: therefore having a large sleeve where hiding your hands is a good advantage. You also want to concealing carry along ingredients and amulets ensuring them protection from thieves and ease of access: this is again achieved by having those item under you clothes and easily accessible to you. [Answer] Maybe normal cloth disturbed the mana flux and mages attire is designed to make it easier to absorb mana from the ambient. Also there is the cultural factor as mages generally are pictured as a highly educated class, so there is space for elitism and need for distinction,mages are manipulators of the laws of the reality not a peasant making fire balls [Answer] Given that most games with an equipment system have mage-type equipment give mechanical bonuses to magic, I would go with **it actually makes you better at magic**. Maybe the clothes are specially designed to make it easier to concentrate and do the gestures, or the material itself is magically conductive (perhaps also providing a degree of protection from enemy mages), or something like that. Alternately, perhaps it could even be a placebo effect, a [magic feather](http://tvtropes.org/pmwiki/pmwiki.php/Main/MagicFeather) where you're a better mage simply because you feel like one. This could tie into the tradition aspect other answers have mentioned, and would probably work best in a belief/intent based magic system. [Answer] ### Comfy clothes help mages concentrate You wouldn't want to accidentally lose your concentration when casting a spell. That happened to *Bilbo The Hairless One* for example and everyone know how long his beard was before the *incident*. Being in your favourite pair of super-fancy wizarding clothes that you always wear when casting spells helps you maintain your concentration. The better a mage the less rituals he needs to maintain concentration, but especially for newbie mages it's important to have some things that are consistent when casting a spell. And you want to make sure that the clothes are not itchy, or else you might end up as *Tsahra Wo We Don't Talk About* who suddenly started swearing while casting her *Fireball* spell... The rest is tradition. [Answer] The classic D&D explanation is that armor impedes magic. There are somatic components (try making grand sweeping gestures in plate armor). There are audible components (try moving silently around a circle without clinking chain mail). There are physical components (how many pockets does leather armor typically have? Are pouches on belt sufficient?). And that's before we get to the weird ones like "mage must be skyclad" in some traditions (clad only in sky... aka, naked). Besides, as a warrior, you want your mage easily pierced, in case he/she gets uppity and starts thinking they run the party just 'cause they've been to school and can math and stuff. Never work with an armor-wearing mage... it's like working with the valedictorian-quarterback-artist. You'll never get the attention you deserve. [Answer] Sense it looks like my question is going to be put on hold, I might as well post what I ended up deciding. This is mostly a combination of Renan and Chris M's respective answers, but everyone who posted deserves credit. Magic users, like all tradesmen, fall into two categories: Masters (who have apprentices) and *Journeymen*. Journeymen mages travel from town to town selling their trade and as such need to advertise. In the past, a few nations mandated that magic users must wear large pointed hats while in public (after all, they could be considered untrustworthy hypnotists and are technically always armed). Even after those laws were repealed, magic uses everywhere took to wearing the hats to highlight that they were capable of useful, employable magic. Not only that, but wards, siguals, and ruins that are beneficial to magic users started to be Incorporated into their clothing. Robes are occasionally used due to their high surface area, but cloaks and ponchos are more practical for the traveling Journeyman mages. In terms of game mechanics, maybe mage clothing could allow for additional charm/accessory slots that are needed to boister the power of magic users' spells. Now their potential gear includes pouches, straps, and big pockets to suggest why this is the case. This does create the strange image of a wizard in a bright cone hat, a runic poncho, and cargo pants facing down the forces of evil, but I consider that more of a feature than a bug. Thanks to everyone for the help. [Answer] Many excellent answers, but I would add that the robes could be a sort of uniform or badge of office. Beyond simply being a symbol of status or a visual warning or cue to others, they could be used as a visual sign of being granted official legal privileges/powers. As an example, in Raymond Feist's Riftwar series of books, one of the cultures within the setting has empowered (most) magic wielders with special legal status. These individuals all wear black robes to denote their status, and are often even referred to as "Black Robes" - demonstrating the significance their signature wardrobe has gained in their society. Of course, this is highly setting dependent. ]
[Question] [ I want to have a post apocalyptic world where 21st century tech is unable to be made anymore due to humans using up all the resources on the planet. Since space programs also use computers, there should be no way to get to space either. The problem is that I do not know if it is feasible for the human race to run out of enough raw elements to make consumer electronics. It is acceptable to have some of that tech to still exist, I just want to know if it is feasible or realistic for humans to run out of stuff like copper, gold, etc. I would preferably like the world to be set in 2080, if so possible. I am willing to go up to 2110 if not. There are no sci-fi elements, like aliens and such, except for the wasteland that is earth. [Answer] **What does it mean to have depleted resources?** With the exceptions of atmosphere that has sublimated into space and mass converted to energy by nuclear power and bomb testing (and maybe a few other things, but you get my point), every atom of material that started on the planet is still here. Through chemistry, we've manipulated those atoms, but they're all still here. The idea that a point in time could come where a critical material needed for manufacturing electronics was gone is hard to believe. One would only need to start digging up old trash dumps to get access to those materials and fire up chemistry to recycle them. **So, what's missing in a post-apocalyptic world that would prohibit high-tech manufacturing?** * The supply chain. Most people don't realize just how large and complex the high-tech supply chain is. It's *massive.* And one of the reasons it's massive is that an honest analysis of the supply chain can't ignore dependent chains. All those raw materials that go into an integrated chip. That go into the machines that make integrated chips. That go into the tools that maintain the machines. That go into the machines that make the clothes of the people who perform the maintenance. That go into gathering, processing, and shipping food that feeds all those maintenance workers. And that was just an infintesimal sliver of the supply chain. That supply chain simply won't exist post-apocalypse. * Some chemicals are very hard to handle. During a safety class at my first post-university job, one of the fabrication scientists was reviewing how to manually detect dangerous chemical situations (never trust the automation!). One of those chemicals was hydrogen cyanide, which at that time was used during the integrated circuit manufacturing process. He explained that it smells like almonds — o'course, you're probably dead at that point, so the idea was primarily academic. My point? Post-apocalypse you might not have the ability to handle the dangerous chemicals needed for or produced by high-tech manufacture. * As @L.Dutch mentioned (I upvoted his answer, you should too) post-apocalypse you might not even have the ability to build and/or maintain the machines needed for high-tech manufacturing. Remember that supply chain I mentioned? There is a similar "knowledge chain" that's required for those machines to work for any length of time. Scientists, engineers, and technicians from the machine manufacturer down to the machine user and you need all of them. Take too many of them out of the "knowledge chain" and you get the same kind of collapse you see when you disrupt the supply chain. * And speaking of chains... there's also the need for electricity (a LOT of it), water (a LOT of it), waste processing (a LOT of it)... But if we ignore everything and only focus on electricity, high-tech manufacturing facilities use their own substations. Their power requirements are enormous. You're post-apocalypse, so let's simply consider running train after train of coal to the local power plant to keep the power going. I live next to train tracks that run eight coal trains, each 2 miles (3.2 km) long, seven days a week. I'm told they supply one power plant in Washington. (And the supply chain... miners, train workers, dock workers... repair/replace trucks, diggers, train cars & engines, track...). **And then there's Mad Max...** You just can't have a post-apocalyptic world without the kind of drama we saw in the Mad Max movies. Oh, it's not the Hollywood flash-bang I'm talking about. It's the sense of lawlessness and chaos. High Tech depends on stable civilizations and stable governments. Why? As an example, it's a *whomping big deal* when a fabrication facility shuts down. A small facility can lose a million dollars a day. A big one can loose a million dollars *an hour.* Planned shutdowns for maintenance are one thing, but the power suddenly shutting off is very much another! The one time I remember it happening, the company literally just sent everyone home. All of us, right down to the janitors. Every possible penny of expense was salvaged while the building support staff worked around the clock to get the power back online. Yup, these facilities have backups after backups after backups — but nothing is ever perfect. If it's that sensitive in the Real World, imagine the problem of keeping one running with twenty cars circiling the facility shooting bullets into it. **Conclusion** While I don't believe you can rationalize the inability to manufacture high-tech due to a lack of resources, I think your real problem would be rationalizing the ability to manufacture high-tech at all. There's so much *civilization* that high-tech depends on — and post-apocalypse, some or more of that civilization is usually gone. *@AlexP makes a good point: as the size and stability of post-apocalyptic government increases, so does the ability to manufacture high-tech components. Given the inevitable amount of equipment left over after even a classic apocalyptic event, the odds are very good that 1960-1970 grade electronics could be manufactured almost immediately, 1980-1990 grade electronics within a few decades, and 2000-2010 electronics a decade after that. Humans are nothing if not tenacious — and we've decidedly proven that we love our cool gadgets.* [Answer] Making state of the art electronic is not only a problem of materials, but also of technology. While any amateur can expose board with a resolution of several microns, going to the nanometer scale requires [complex machines.](https://www.researchgate.net/publication/334136595_EUV_Lithography_State-of-the-Art_Review) > > Although several years delayed than its initial plan, extreme UV lithography (EUVL) with 13.5nm wavelength has been finally implemented into high volume manufacture (HVM) of mainstream semiconductor industry since 2018. With the delivery and installation of ASML EUV scanners in those giant Fab players like Samsung, TSMC and Intel, EUV lithography is becoming a sort of industry standard exposure metrology for those critical layers of advanced technology nodes beyond 7nm. Although ASML NXE EUVL scanner is the only commercialized EUV exposure system available on the market, its development is the concentration of all essence from worldwide industrial and academic collaboration. It is becoming more and more important not only for fab runners but also for main stream fabless design houses to understand and participate the progress of EUVL. > > > And to make those machine one needs also the electronics made with those same machines, or those from the generation before. To put it simply, you can have all the silicon wafers, gold, copper, indium etc. of the world, but if you don't have a litho fab you won't get any decent (for today standards) electronic. And that is way more easy to achieve in a post apocalyptic scenario. Vacuum tubes might be done, but will never achieve the performances of today electronic. [Answer] This is not feasible. Most of the chip is silicon coming from just about anything, Earth is full of that and it is not too difficult to purify to something reasonably good. Dopants are common. The remaining materials such as rare earths are available mostly everywhere too. Yes, there are some countries dominating the supply. But this is because they have most suitable deposits, laws, tools and know-how to make extraction and purification profitable on a large scale. I daresay 90%+ of countries could get all required materials for chip manufacture on their soil, it just wouldn't be environmentally friendly or cost effective, so they don't. But blow up / infect / ... the rest of the world and Madagascar as the obvious safe spot becomes the world powerhouse in chip manufacture. So, you need to break down everything. JBH's answer talks about supply chains and this is a good starting point. The main problem with it is that an ancient process doesn't require all that much fancy stuff, especially as we have worked out most of kinks. You can prevent 2020 tech. Perhaps make 2000 tech need many years to get back to. But 1970s tech can be set up fairly fast after complete collapse. Next step would be that people forgot how to make chips. You can't really do that, unless the apocalypse wipes out adults and leaves just children alive. They would remember what glorious toys they had, but have no idea how to make them. Yet another way of stopping chip manufacture is if your chips were responsible for the apocalypse so nobody wants to make them - but this is a fairly common trope these days. [Answer] **Have difficulty yes, unable no** For the working scenario I take a process of recovery from post-apocalyptic state when commercial stability has been restored, and there are resources to resume production of the more and more technologically complex products, but lack (or expensiveness) of raw resources creates obstacles on this path. Some of the resources that our civilization is using are considered non-renewable, such as oil and gas. Ores, on the other hand, while non-renewable, can be recycled. There are not so much easily accessible gold deposits anymore, but most of what people have mined so far is recoverable. The only question is the price of it. So, under this working scenario it is possible that recovering civilization can be starved off certain materials that are presently necessary in electronics. Gold is one such example, rare earth elements is another. However, semiconductors in general should not be affected. Silicon, as well as most doping elements are broadly available and in not in any realistic risk of depletion. With realistic depletion, the cost of new gadgets may make them too expensive for the consumer segment, but as mentioned above, the elements themselves are still available here on Earth, research and development would still be possible, albeit at a higher cost. One notable exception to this is Helium. While almost all other elements stay put on Earth, Helium, once extracted from the Earth cavity, eventually escapes to space. So this new civilization may have to cope with shortage of helium, which would put restraints on its superconductor research and fields related to it. [Answer] Materials required to fabricate many types of electronics compose roughly 50% of the Earth's crust. It would be virtually impossible to get rid of them all. [The earth's crust is made of...](https://www.sandatlas.org/composition-of-the-earths-crust/) * 27.7% silicon * 8.1% aluminum * 5.0% Iron * 3.6$ Calcium * 2.8% Sodium * 2.6% potassium Silicon's primary use in electronics is to make semiconductors (transistors, diodes, microchips, etc.). Aluminum itself is actually a really good conductor. It can be drawn into wires and used to make coils for transformers, electric motors/generators, power transmission lines, etc. Iron, while a much worse conductor than aluminum, is still a viable choice in many cases. And can be used to make stuff like electromagnets and inductors. Calcium Sodium, and Potassium all have their uses making batteries. **It's probably more likely that knowledge, practical expertise, and infrastructure required to make advanced electronics would disappear rather than the actual materials necessary to do it.** If engineering and production facilities of tech-corporations are destroyed, universities are destroyed, libraries are destroyed, and the internet goes off-line that knowledge would exist mostly in the minds of knowledgeable professionals and whatever private reference books they own. If those professionals don't pass on their knowledge to the next generation, it's possible that knowledge could become virtually lost within a generation or two. This could happen either because schools are not operational, professionals are specifically targeted for elimination, or they simply stop practicing their skills and don't take on apprentices (perhaps because they are busy trying to survive, can't get work in that field, or can't get the materials to perform their jobs). ]
[Question] [ The reason I ask is because I want to create a terrestrial species that hunt fish underwater by holding their breath for hours without having a large lung capacity. In someway they are buffed Bajau sea nomads. [Answer] > > hunt fish underwater by holding their breath for hours without having a large lung capacity > > > So, it is a common misconception that diving mammals (humans included!) store much oxygen in the lungs. Indeed, for deep diving mammals, having air spaces in the body is a liability, because water pressure will crush them. Seals and so on have the ability to fully empty and collapse their lungs. The wikipedia article on [physiology of underwater diving](https://en.wikipedia.org/wiki/Physiology_of_underwater_diving) has much more details and is well worth a read. Of particular interest to you, though... [myoglobin](https://en.wikipedia.org/wiki/Myoglobin) stores oxygen in muscles. Diving mammals have a lot more myoglobin in their muscles than their non-diving counterparts, which acts as a large reservoir of oxygen. Similarly, having more hemoglobin in the blood means you can store more oxygen in the blood too, which combines well with having blood storage organs like the spleen. Having extra red blood cells in humans is a well established way to cheat at endurance sports (see also, [erythropoietin doping](https://en.wikipedia.org/wiki/Erythropoietin#Usage_as_doping_product)), but you can also have better hemoglobin too... [crocodile hemoglobin](https://www.researchgate.net/publication/23111643_CO2_governs_the_oxygen_affinity_of_crocodile_blood) gets better at giving up its bound oxygen when CO2 levels in the body rise. [Naked mole rats](https://en.wikipedia.org/wiki/Naked_mole-rat#Metabolism_and_respiration) can survive just fine at very low atmospheric oxygen concentrations, even in the presence of very high levels of CO2 thanks to superior hemoglobin and fancy metabolism. Furthermore, the naked mole rat is also has a superior anaerobic metabolism, seemingly much more resistant to the effects of acidosis than we are. There's plenty of interesting things to learn there, some of which are active research topics, and some of which are just plain mysteries (and therefore give you some scope for handwaving in similar adaptations of your own without too much fear of being implausible or incorrect). Do take a moment to think about *why* your merpeeps need to be able to dive for so long, though. Seals and dolphins and so on are already excellent fish hunters and don't need to spend hours down there... they need to be able to hold their breath *long enough* but beyond that the additional complexities and tradeoffs start looking a bit undesirable. What's the point of having super-blood that means you're at greater risk of thromboembolism and your cancerous tumors get fed much better than everyone else's? Just come up for a breath after an hour instead of after three. The things that hold their breath longest are the deepest divers who *can't* just pop up to the surface for a quick breath of air. What are your creations hunting down there? What's wrong with the stuff in shallower water? [Answer] **Amphibians** Frogs and salamanders do oxygen exchange [through their skin](https://en.wikipedia.org/wiki/Cutaneous_respiration) while underwater. Some salamanders and newts have gills too. [Like this cutie.](https://animals.sandiegozoo.org/animals/salamander-and-newt) [![enter image description here](https://i.stack.imgur.com/hRHUP.png)](https://i.stack.imgur.com/hRHUP.png) Some deep-diving turtles [breath through their ass.](https://en.wikipedia.org/wiki/Enteral_respiration) Or cloaca, the single opening through which the waste goes out and the sex goes in. [Answer] CO2 is produced because our bodies use oxygen to oxidize carbon based substances to get energy, and that leads to the production of CO2. There is no way around it. Putting it into some other substance which doesn't need to be breathed out would need energy, and making so take away energy from the vital functions. Alternatively, you could avoid using oxygen as an oxidizer like anaerobic organisms do, but you would still need to get rid of the waste products, for which the consideration on the energy expenditure still holds. Last but not least, if you run out of oxidizer, the body has nothing to feed the burner to get energy. You can't have long apnea without large availability of gas. The need of breathing out comes from the fact that an excess CO2 in the lungs, even though oxygen is still available, shifts the transport equation toward capturing CO2 rather than oxygen. [Answer] **Anaerobic metabolism.** Recycling my idea from here [Could a deep ocean creature use some kind of bacteria in its body as a way to generate oxygen?](https://worldbuilding.stackexchange.com/questions/96207/could-a-deep-ocean-creature-use-some-kind-of-bacteria-in-its-body-as-a-way-to-ge/96254#96254) ! > > But here is another idea for your creature as regards oxygen: it > minimizes its use of oxygen by using anaerobic metabolism. When humans > do this it is <https://en.wikipedia.org/wiki/Anaerobic_glycolysis> > Energy can be derived from glucose without oxygen in short bursts. > Lactate is the end product and builds up - this is the burn you feel > when you feel the burn. Ultimately the liver has to oxidize the > lactate when there is oxygen around again. It is an inefficient use of > sugar compared to aerobic metabolism but we can do it. > > > But what about a creature that did anaerobic glycolysis and then > ignored the end product? Yeast do exactly this - the end product is > ethanol and it just builds up until they cant stand it any more. Or it > evaporates away. Tapeworms do this and release the lactate into the fecal stream. A sea monster with lots of food and little oxygen > could just let the lactate waste product ooze out of its pores into > the water. It would need a lot more food (I think three times as > much?) than a comparably sized creature using oxidative glycolysis, > which extracts more energy from the sugar. But it could get by with > much less oxygen. > > > Your sea creature does not need to breathe and it requires a lot of food. [Answer] Have you considered gills? There are no earth mammals that have gills, but if your species has them, then your problem is solved. ]
[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/232721/edit). Closed 1 year ago. This post was edited and submitted for review 1 year ago and failed to reopen the post: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/232721/edit) An entity comes to me in my dream and says I now possess the power to exterminate any biological entity of my choice on Earth at the snap of a finger. Without giving too much thought, I decide to exterminate all viruses. Can life on Earth continue to exist normally? (Specifically human life) If not, how will it interfere? [Answer] # Probably Everyone (and Most Animals) Die There's actually an [article on exactly this](https://www.bbc.com/future/article/20200617-what-if-all-viruses-disappeared). > > What we do know is that phages, or the viruses that infect bacteria, are extremely important. Their name comes from the Greek phagein, meaning “to devour” – and devour they do. “They are the major predators of the bacterial world,” Goldberg says. “We would be in deep trouble without them.” > > > > > Phages are the primary regulator of bacterial populations in the ocean, and likely in every other ecosystem on the planet as well. If viruses suddenly disappeared, some bacterial populations would likely explode; others might be outcompeted and stop growing completely. > > > > > This would be especially problematic in the ocean, where more than 90% of all living material, by weight, is microbial. Those microbes produce about half the oxygen on the planet – a process enabled by viruses. > > > So we might all asphyxiate. We might die from bacterial superinfection, given the sudden lack of phages in our internal microbial ecosystems. Other vital parts of the ecosystem might die and it would be a tossup between asphyxiation and when that broken link in the chain of life reached us. Very Bad Things, regardless of which end actually reached us first. --- Edit: In terms of dividing between "immediate" and "long term" - if it turns out that the billions of bacteriophages in our body really are keeping bacteria (healthy or otherwise) at bay, pretty much everyone immediately and messily dies, on the order of weeks. If that's not the case, but we have enormous bacterial outgrowth in the oceans, then the world gradually runs out of oxygen. This would be a months-to-years-long process. [Answer] **Hardly Anyone Notices** The issue with viruses is that they are constantly produced in infected cells, attach to other cells and infect them to make them produce more of the same virus. Your wish is instantaneous, and only kills (decomposes, more likely) all existing copies of all viruses, yet no genetic code gets altered, thus whatever cells are still infected, that is, have virus genome embedded into theirs, would just make more of that virus effectively recreating the majority of virus ... constructions. Some viruses might effectively get extinct, if they only exist in forms like a cyst, or sleep for some eternity within existing cysts, that have virus genome within but do not produce any viruses because of anabiosis, but anything active will just get reproduced. [Answer] Here is a sort of a frame challenge. Your quesiton is inconsistent. You write: > > An entity comes to me in my dream and says I now possess the power to exterminate any biological entity of my choice on Earth at the snap of a finger. > > > The entity that comes in your sleep is a single supernatural being. So it should be offering the power to kill any single organism. But your word "exterminate" means to kill all the members of a group. So the offer might possibly be interpreted as an offer to kill all members of a single species of organism. You follow with: > > Without giving too much thought, I decide to exterminate all viruses. > > > For one thing, it is a matter of debate whether viruses are lifeforms and covered by the offer. For another, "all viruses" are not a single individual virus, nor even a single species of viruses, but every genus, family, order, family, class, etc. of viruses, an entire kingdom of life. It is very hard to imagine that the word "entity" could be stretched to cover an entire kingdom of life. So possibly you might want to have your character's initial request denied by the supernatural entity because it was ungrammaical and ilogical, and have them argue about whether exterminating all viruses fits the initial offer, before the character convinces the entity it does. So if, as some answers suggest, the wish has very little effect on one hand, or causes everyone to die on the other hand, the readers will more easily accept that the character hasn't thought about his wish enough, if the entity has criticized it for being ungrammatical and illogical and scientifically illiterate. Possibly the entity was some sort of supernatural or scientifically advanced being sent to destroy the human race, and for its amusement chose to do so by giving half awake humans, not thinking clearly, one wish each, expecting that sooner or later one would make a not carely thought out wish that would destroy all humans. ]
[Question] [ As I type these words in March 2021, there are numerous private companies developing engineering solutions for reliable, high-capacity and relatively cheap access to space. At this point in time, it appears plausible to imagine that the first demonstration refineries and matter processors would be on the Moon before the decade is out. With its puny gravitational field, this means cost per Kg into space from the Moon would be trivially small while still allowing relatively close control from Earth. With better automation, costs might be even smaller per Kg from the asteroid belt, since despite the distance the delta-v budget is even smaller. This in turn means the only constraints to building megastructures in space and seeding colonists on various planets and moons come from the lack of an obvious economic need for such things. The current value of our assets in space is somewhere around USD 400bn, a tiny sliver (<0.1%) of Earth's value stock (currently valued between USD 400tn and USD 5000tn), and that's mostly an artifact of the high cost of launches. But, we have to remember that, once in place, most of these space-, belt- and moon-based assets can run on "free" solar power and would likely be highly automated, which means that once the initial infrastructure costs are sunk, maintaining a high rate of material output can lead to exponential growth in capacity. Imagine the kind of GDP growth seen in the industrialization of China, except with untiring robots that can produce more untiring robots, which in turn produce yet more infrastructure, etc. Space GDP growth upwards of 100% per year seems strangely plausible in the early decades of this process, which might mean that space GDP may eventually exceed terrestrial GDP, even with very few people actually in space yet. Admittedly, the idea that constructing artificial habitats in space could end up being cheaper than purchasing and developing equal amounts of suburban land, exurban land, deserts, tundras or floating cities on Earth seems implausible currently. The cores of our biggest cities have huge valuations, but land is still currently cheap and plentiful elsewhere. In addition to temperate agricultural-friendly land, we have vast deserts, tundras, shallow seas. How could building an O'Neill cylinder in space be cheaper that building the most luxurious home downtown or in the suburbs? After all, we have the industrial capability on-world, air comes free, we have power grids, water, communications, relatively easier access to social and cultural centers, etc. My best guess is that at some point, a combination of increased ecological consciousness (already seen in the reforestation of large tracts of Europe and North America) and good-old-fashioned NIMBY-ism will make further industrial and urban development on Earth impractical and increasingly expensive. Moreover, human access to space does not need to be (initially at least) a mass-market appeal proposition. You can have a cheap home in the back-wood taiga if you want, but it is not **cool**. So early human habitats could be built for entertainment or a way to signal high social status -- I can imagine the appeal of having say a wedding ceremony with the Earth looming large and blue over the celebrants, or a billionaire inviting her friends over to her O'Neill cylinder. So it seems moderately likely that the number of humans in space is set to increase over the next few decades. My question is, given all I've discussed and any additional points you care to bring up, when if ever can we expect the off-world human population ever to match or exceed the human population on Earth? [Answer] > > pace GDP growth upwards of 100% per year seems strangely plausible > > > it can be even bigger than that, it all a matter of energy [EROEI](https://ru.wikipedia.org/wiki/EROEI) of that automated ecosystem, it can be a month or even less for 100% growth. > > Admittedly, the idea that constructing artificial habitats in space could end up being cheaper than purchasing and developing equal amounts of suburban land, exurban land, deserts, tundras, or floating cities on Earth seems implausible currently. > > > Implausible? No, it will be exactly what happens - cheaper, cheaper than a tonne of dirt you can buy here on earth. > > How could building an O'Neill cylinder in space be cheaper than building the most luxurious home downtown or in the suburbs? > > > Cities on the planet are the most expensive constructions we own, we build and put resources in them for hundreds of years and that process never stopped. We maybe chip a fraction of resources and power for that, but it is not such a small fraction, we could or would like to chip more for the goal, because it would be mean cheaper real estate, but we can't as we need those resources elsewhere as well, including to support other technological structures and infrastructure in between. But if it could be easy - we would absolutely do because population growth and a place to live in is one of the fundamental necessities for all sorts of reasons. If we would imagine a necessity or a desire to build a freshly new city from scratch for let's say a million people, which is not even a big number for the good portion of countries - for any of those countries economy it would be a big burden, a job of titanic proportions. > > After all, we have the industrial capability on-world > > > For any noticeable progress in space, technologies have to be moved in space, exported in space, we need to have them in space if we think about anything human-related on a scale of more than a thousand people. > > So early human habitats could be built for entertainment or a way to signal high social status > > > Nah, not doing to happen, it like that argument that tourism will propel space exploration and all that. And if you look at numbers on how much money is spent on \$50k and more expensive tours - the market cap isn't high at all. At least, when I did such research I wasn't impressed. yes, one can spend a billion on a yacht, and space hab may be considered to be a yacht-like expense/investment - but without a change of technological paradigm in space how big it will be? Will it even be a space hab. We do have some number of riches on the planet, and how much out of them are space-oriented? Five? I'm about right, eh? And who succeeds? One, maybe a second as well but it takes a long time for him. They do have all the billions, all the billions they need but it does not look like enough, nor are the results that impressive. SpaceX is good, and I expect a lot from them, but yeah, it a long way to space habs that way. So if we see space habs only if it will be interesting for many people. If the move promises them something better in terms of opportunities or future or present. Riches can make a pinhole, at best, the flood which breaks the wall is the people. Those riches who get rich forsee and cave in for the needs and desires of these many people. That's your frame challenge if you like. ## Can space be cheaper than Earth Let's see which prerequisite we may have in space. Can goods be cheaper than on earth? Live cheaper and better? Solar energy is on the rise on the hype, for quite a long time on earth. But let's see what it is in space, right? The same solar panel as one my use on earth, let's place it in space: * it gets 30% more power, just because there is no atmosphere * it gets around 3-4 times(not an exact number) more sunlight just because there is no day/night cycle * no weather, not blackouts - constant supply of constant power So energy price, in the case of solar panels, without a change of technology - can be improved about 5 times, compared to the same on the planet. Solar for space, at least in our orbit, is one of the most convenient sources of energy, and that 5 times difference does not end yet, continue: * the panel does not have to be strong, robust as it is in a microgravity * there is no wind that tries to rip it off * not water, no snow - which tries to corrode it So for the reasons and conditions which are in space, a panel loses weight considerably, and that are the materials on which we do not have to spend energy to produce them, making the thing even cheaper, improving EROEI. And here is a nail in a coffin of expensive - food-grade foil that can be used to concentrate light. Do you know those stations?[![Crescent Dunes Solar Energy Project as seen from an airliner](https://i.stack.imgur.com/ihmG2.jpg)](https://i.stack.imgur.com/ihmG2.jpg) This is [Crescent Dunes Solar Energy Project](https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project), and its construction cost is $0.9B, for production, if everything is good, 110MW. In the picture, there are about 10'000 mirrors, and I guess it easy can be at least 10 grand apiece, and the mirror isn't that big less than 70 square meters, and that amount of aluminum foil in small rolls costs about less than 20 bucks (two rolls 44 meters each). And it will concentrate at least a few times more energy. So how about that as price slashing - 10 grand best cases vs 20 bucks worst-case prices. Energy prices can be orders of magnitude cheaper, there is just no way we can dream about such prices even if we get fusion working. Not talking about no need for land reclamation, works everywhere in orbit. There is no way we can achieve that in foreseeable future on earth. But that isn't the most fun part of it, if you still there, let's get to the fun part ## Goods, can they be cheaper? Take look at your phone, tablet - those are small devices, they are technologically advanced devices, but the amount of materials used in them is small. Do you think, that you would sell the materials, raw components - will you get even 1 percent of the sum you paid for the device? The main cost of production, not the design, is the energy we use in conversion of initially small amounts of materials - shaping, purifying, etching, cutting, etc. And on the production of tools, we use in the processes. **Energy is the blood and air** of technological society, civilization. Wages in the production business are about, 20% of expenses in a place where I live, and the rest can be attributed to energy this or another way - wear and tear of equipment, direct energy expenses, raw materials - those are the main expenses. Raw materials - making steel as an example - energy expenses are the main expense in that process. Wear and tear mostly the same problem - spend energy to shape blanks and raw materials in some product, which makes the tool which wears and tears - to replace or make a brand new tool, and recycle the old. Recycling - the same main problem is in energy for the separation of things in useful composition. Nothing works in modern society without electricity and energy and it is an important part of GDP and its availability and its prices will be reflected in all the products which are made. So they absolutely can be cheaper multiple times cheaper, especially if there is enough automation. And especially those which are high-tech units. **A lot** can be said here but if you connect the two dots - you will be on a right track for anything else. # Speeds and feeds The prerequisite for human expansion is exporting technologies in space, in its full capacity basically, it may be not that hard as many may perceive that problem, won't be easy as well. It can be significantly cheaper than many think, in terms of what we need to get in space to bootstrap that, and most of the work should be done here on earth, in a sense of designing systems and collecting technologies in a suitable package. Exporting technology in space is a big topic, but it is a necessity if you like to think about human expansion and an absolute necessity if you think about overtaking the earth's production capacities. It will take some time, but again things may be simpler, as bootstrapping technologies can be quite limited and not great in numbers, and the rest we can transmit over the link from the planet - so mostly a groundwork on the planet - how much it may take - there is no way to say this - a decade may be more than enough. ## Growth At quite extremes but the speed of **growth of technologies**, meaning production capacities, can be extremely high, like 100% every 3 days, based on EROEI. It will be different for different products, energy production is most basic, most important and fastest. With some lag next level production, next next level, and so on. But in the end, the first most basic layer in the technological pyramid will define the power of production output, and the whole pyramid establishing may take few years, depends on how you do that, how prepared you are. if you have all the plans ahead of time then it may take a year or something around that time, if not then a decade. So for multiple reasons, a topic for a different q, technology won't be a source of the bottleneck. **Human growth** is about 2 percent per year, but it is a number that can be regulated and the results of it take time if we talk about natural means to grow people. 2 percent of population growth is a relaxed number it can be higher and it can be lower no matter the other factors, but with 2 percent nobody is stressed, everyone has time for many things, one of which raising humans. 2 percent growth, per year, means in a century it is a 7 times increase of initial population. So if you start with a million then it just 7 million after 100 years. But with technologies exported to space it possible to lift everyone who wishes to live in space, so the number may be bigger, to begin with, but it depends on the living places. * **my apologies here**, 2 percent, remembered the number incorrectly, history-wise there were 2.2 percent and a bit more, but today's averaged around 1.2 percent. All statements are still true, and it can be considered to be one of the fast versions of growth, but it may be more than just 1-2-3 kids in a family which is more like the modern way with all that. But all that does not affect conclusions or potential timeline. ## Space habitats it a topic on its own, but what is related to the question of speed of growth - is the attractiveness of those places. Easier access to technological products, food, resources for personal and group projects - definitely may attract quite a number of people. Have 5 time more for the same work - quite good, maybe - work less, have more - like that better. So we may expect a potential of a billion or even a few billion people to consider the idea to move in space, but if their environment conditions will be good enough there. if environmental conditions will be good - spreading the idea and catching up on it and moving to the idea to move won't be difficult in our days - youtube will help, or whatever user governed analog will there be in that time. But designing, ironing the inside of space habitats will take time. We not exactly starting from scratch, and there may be healthy ideas out there about nuances and stuff, but ecological microbiological aspects it will take time - decades. All in all, it may start with 10-100million people. Space and that growing expanding situation is the real future and where real opportunities and real rewards for your effort are, so based on regular migrations in the world, the number may be quite realistic. And better are the conditions, faster people move. So growth probably will be mostly due to the move from the planet in space, so it may take less than a century before space population will be bigger than earth one, and thus make more and have bigger numbers in everything. ### side note This is one of the aspects I hate in The Expanse. besides water, another aspect which irritated me the whole seasons is that - man, you already in space, nothing separates you from turning the sky with your hands why aren't you doing it - why???!!!! There are thousands of roads to heaven and no road to hell, but you manage to breach into hell - how, why, aaaaaa!!! LoL ## Conclusion The most critical part is exporting technologies in space, until it has done, nothing extreme will happen. Mars won't happen. Space habitats won't happen. And as long as this part is postponed, by so much you can delay the expansion. A century, few, as many as you pleased with. The rest, dust most likely settles in 50 years after that. [Answer] I'm probably gonna have to go for "not in the next few centuries", and it isn't beyond the realms of possibility that the answer will be "never". Here's the thing: it is *rubbish* out there. Radiation soaked, freezing or roasting, gravity all wrong, toxic razor sharp ultrafine dust everywhere. Terraforming anything in any meaningful sense of the word is so mindbogglingly implausible it may as well be magic. What you're left with then is the construction of habitats, which are a bit like cities you can't escape from and where failure to follow the rules could put you or everyone else's life in jeopardy. There will always be ceilings. The only oceans will be under kilometres of ice. Returning to Earth will still likely be expensive and unpleasant and risky. > > My best guess is that at some point, a combination of increased ecological consciousness (already seen in the reforestation of large tracts of Europe and North America) and good-old-fashioned NIMBY-ism will make further industrial and urban development on Earth impractical and increasingly expensive. > > > Industrial stuff can be moved (what's the planetary equivalent to "offshored"? outwelled?) and probably will be once it becomes cost effective... the most polluting and destructive things would be moved out there because if nothing else there's lots of easily available power and once you've solved the transport problem, lots of convenient raw materials, too. But people, though? that's a much tougher proposition. > > Moreover, human access to space does not need to be (initially at least) a mass-market appeal proposition. You can have a cheap home in the back-wood taiga if you want, but it is not cool. > > > It would indeed be awesome to take a trip out to a big habitat at the Earth-Sun L1 point... the view back towards Earth and the moon would be amazing. Thing is though, you might not want to live there. People have holiday homes and stuff now in places where it is nice to visit but incompatible with their lifestyle to remain there. Experiencing the reality of being on an expensive cruise ship where there are worse things that norovirus that can happen to you is not likely to encourage emigration. People will, of course. People want to go live in Musk's Mars habitats, which will be effectively be prisons given how unhomely and thoroughly policed they'll need to be. The prospect of debt-slavery to a bunch of libertarian techbros in a place where you need to *earn* your next breath is no discouragement to some! They'll be few and far between compared to the bulk of Earth's population. Remember that human population growth rates *slow* as people become safer and healthier and (comparatively) wealthier. Running out of living space on Earth may only be something to worry about in the relative short term, and space in Space is going to be every bit as cramped and expensive as a city apartment (if not more so!) whilst that particular population peak is experienced, but as Space gets cheaper you might expect there to be less pressure on living room on Earth, and so the drive to leave will be reduced, too. [Answer] Historically, colonization and emigration hasn't been driven by profit, but by lifestyle -- specifically, people colonized or emigrated because they hoped for a "better" life than they had in the "old country." America has recent enough history of this to have good records -- the first colony north of Florida was founded by those fleeing religious persecution, or seeking to live better than they could as bond servants or farm hands in the Old World. For the next four centuries, people came to America because they wanted a better life, if not necessarily (realistically) expecting it for themselves, then for their children and grandchildren. Once people have the ability to *choose* to live off Earth, there will be some who do so for this same reason -- and they'll be the ones who find ways to support and raise families, despite different gravity, no air outside the "house", and so forth. Only after that's been going on for a good while will there be more people off Earth than on it (the population of the United States still doesn't exceed that of Europe, or if it does it's very recent and not by much). If Elon Musk succeeds with his plan to colonize Mars in this century, we can expect that to start -- but it'll take a very long time for off-Earth population to catch up with the ability of eight billion people (and counting) to reproduce. [Answer] /How long will it take for the off-World population to exceed Earth's population?/ Answers so far have concerned themselves with the off world population. But what about the on world population? [![relic](https://i.stack.imgur.com/qFuaU.jpg)](https://i.stack.imgur.com/qFuaU.jpg) <https://www.deviantart.com/jflaxman/art/Relic-538709214> What great concept art. Well done Flaxman. I am reminded of Ozymandias. "Billions and billions served". In any case - there is some fancy expensive stuff happening off world. Boutique getaways. Pilot mining operations. Planetary surveyors. But then Earth becomes much, much less nice. These few and diverse space folk find themselves the hope for their species and maybe their phylum. [Answer] I have written an entire series of books on this topic, so I have a lot of thoughts: ## Generational Cycles Some may not know that the [Apollo program was extremely unpopular](https://www.history.com/news/apollo-11-moon-landing-launch-protests). No less a luminary than Martin Luther King's successor, Ralph Abernathy, [spoke in extremely strong terms](https://www.theguardian.com/science/2019/jul/14/apollo-11-civil-rights-black-america-moon) against the moon landings. Steve Bannon popularized Howe & Strauss [four turnings](https://www.fourthturning.com/) idea to explain why we do such things. It's a coloring-in of the "rags to riches to rags" idea, but more simply (and to the point of this question) : we have a single generational (20 to 40 years) tolerance for trying out big leap forwards. Then, historically, we wait 60 to 120 (let's say 70 to 90 to keep in the mean) years before doing anything else bold. After Apollo, we took a 70+ (still not over) year break from manned flights out of Earth orbit. Space Shuttle was an idea to keep us in space for pennies compared to the Apollo program. ## Required Leaps to the Inner System For my series, I used a number of 90 years between big leaps forward. Here's all the things we need to do: * Reduce the cost to get out of Earth's gravity well : + \$200,000 per kilogram ([1960s](https://aerospace.csis.org/data/space-launch-to-low-earth-orbit-how-much-does-it-cost/)) + \$20,000 per kilogram (1970s) + \$10,000 per kilogram ([now](https://www.nasa.gov/centers/marshall/news/background/facts/astp.html)) + \$200 per kilogram ([space elevator - proposed](http://www.niac.usra.edu/files/studies/final_report/521Edwards.pdf) TRL-1) + Pennies per kilogram (orbital ring - proposed TRL-0) * Reduce the time, increase the payload percentage, and decrease the cost to get around in the inner system + Not Possible (pre-1970s) + 3 months / 92% fuel - 8% payload / \$261,000 per kilogram ([now](https://www.reddit.com/r/Mars/comments/42rs7k/cost_per_pound_to_mars/)) + 1 month / 72% fuel - 28% payload / \$74,000 per kilogram ([torch drives - proposed](https://worldbuilding.stackexchange.com/questions/181093/performance-envelope-characteristics-for-a-hard-sci-fi-torch-ship), TRL-0 25% reactant burn - 0.000036% mass-energy efficiency) + 1 month / 24% fuel - 76% payload / \$6,000 per kilogram ([torch drives - proposed](https://worldbuilding.stackexchange.com/questions/181093/performance-envelope-characteristics-for-a-hard-sci-fi-torch-ship), TRL-0 100% reactant burn - 0.000144% M-E) + \$85 per kilogram (peak fusion 0.0075% mass-energy efficiency) + \$0.85 per kilogram (antimatter @ 0.75% mass-energy efficiency) ## Putting It All Together * I feel like we're going to miss this window (2010 to 2030), or at best put a permanent robotic settlement on the Moon and Mars. * During the down window (2030 to 2120) I hope we might leap-frog fusion into anti-matter technology * During the next opportunity (2135 $\pm$15) I'd like to imagine the first no-joke permanent settlements start springing up in the inner and outer solar system. * And during the next down (2150 to 2240) we build up those inner system settlements so that they might think of themselves as economically independent. Hopefully, maybe at this time, we could try to launch something for the nearest few stars. * At the next exploration phase (2255 $\pm$15) we start seriously settling dwarf planets in the cometary halo past Neptune. Anti-matter becomes mainstream. Maybe a Not In My Backyard movement makes this anonmyous mass-energy the big import, and injects some wealth. * At the next exploration phase (2345 $\pm$15) we seriously reach for a permanent settlement on [Sedna](https://en.wikipedia.org/wiki/90377_Sedna), which will have just passed it's closest approach. This is when, in my opinion, a few centuries of maturing and emigration from Earth will put the rest of the solar system at an equal level of political clout to humankind's homeworld. But, I'd be surprised if the population of the rest of the solar system combined equalled Earth's at this point (it's just so much easier to grow a population here). However, perhaps only another century later (2450), I think the multiplier effects of so many additional places outside of Earth, and time spent maturing, might bring populations equal. [Answer] ## Let's start with what we know [![enter image description here](https://i.stack.imgur.com/3rSfCm.png)](https://i.stack.imgur.com/3rSfC.png) Click on that image for a larger version. Image courtesy [Open Oregon Educational Resources](https://openoregon.pressbooks.pub/envirobiology/chapter/4-3-the-human-population/). I intentionally searched for an image with a starting point as far back as reasonably possible. Obviously, the beginning number is increasingly a wild guess the further back you go. But we only need it to get far enough back that we have a sensible starting point. **The Premise** Let's assume that humanity's basic nature doesn't change. If we believe that's not true (e.g., if we believe humans will become more environmentally conscious, or more population-growth conscious, or anything else that affects the growth curve just presented), then this question is 100% opinion-based because there's no way to guess how humanity will behave in the future.1 Let's further assume that space technology has increased quickly enough that we can ignore the time between launches. In other words, since there is nearly no population growth on the graph between 1,000 and 1,200, we can assume we have 200 years to get some number of people out there. Finally, let's review some reality. * Even a planet is capped in how much population it will support. Don't get me wrong, I think Earth can hold a whole lot more people than it does right now — but there will be a cap. The cap may be politically imposed (through policy or war) or environmentally imposed (even science doesn't let you grow more crops), but there's a limit. I won't even speculate as to what a planetary limit is, but it exists. This is why, below, you'll find me saying that a single planetary colony can at best equal Earth's population. Multiple colonies are required to exceed it. * Next, in a moment I'm going to tell you I'm ignoring space habitats. There's no point to building a space habitat with the same population potential of a planet and no practical reason I can think of to build so many habitats that they'd add up to the population potential of a planet. The idea that building space habitats could become so cheap that we'd expand off-planet at a rate faster than we can birth children on-planet violates every rule of economics I can think of. Habitats, obviously, have greater resource limitations than planets and would require shipments of raw materials no matter how good the recycling is. Besides, the idea of building a habitat that could house, say, 10 billion people and then start them off with just 400,000 (using the chart, above)... I can't think of a bigger waste of time, energy, and resources. Someone would need to give me an incredibly good reason why that would win out over a station that can hold, say, 1,000 people for scientific research or a communications outpost. Anyway, long story short, since habitats (in my book) have a dramatically lower population potential than planets, I don't consider them even worth considering. **How long will it take for Mother Earth to become a minority?** You're not getting a fixed date. Anybody who gives you one should be down-voted, because it all revolves around (a) how many locations can be seeded and (b) what the maximum population potential of each location is. I'm going to ***entirely ignore*** space habitats. The belief that a habitat (or many habitats) can be built to support billions on the order of multiples-of-Earth is, frankly, impossible to believe. That would put us beyond a [Kardashev Type II civilization](https://en.wikipedia.org/wiki/Kardashev_scale), and IMO that makes your question unanswerable because that level of technological advancement seriously impacts the nature of the above growth pattern (and may happen so far into the future that it makes the predictability of the reference population number impossible). That leaves planets. I'm an optimist2 in that I believe we're going to find habitable, colonizable planets.... Which means I'm also going to ***completely ignore*** the expected activist-driven, environment-first, humans-suck politics that would fight tooth-and-nail to stop colonization because that effort would also impact the predictability of the above chart. **TL/DR; My Answer** Given that each colonized planet has the population potential of Earth, how long would it take for the off-Earth human population to outnumber Earth's population? The traditional equation for population growth is: $$P = P\_0e^{rt}$$ * $P\_0$ is the starting population. * $r$ is the percentage rate of population growth. * $t$ is time. * $e$ is the Euler number (2.71828...) We can ignore just one colony. For that case, $t=\infty$ because, basically, the one colony can't catch up to Mother Earth unless the birth rate of the former is magnificent or something like a catastrophic world war decimates the later. Neither is at all predictable, therefore we must rely on the chart, which means $t=\infty$. For two colonies... $$P\_0e^{rt\_0} = P\_1e^{rt\_1}$$ and solve for $t\_0-t\_1$. For two colonies (here's where a better mathematician than I could help make the formulas look nice). $$P\_0e^{rt\_0} = P\_1e^{rt\_1} + P\_2e^{rt\_2}$$ and solve for $t\_0-t\_2$ or... for any number of colonies. $$P\_0e^{rt\_0} = \sum\_n^0 P\_ne^{rt\_n}$$ and solve for $t\_0-t\_n$. *Note that I've assumed $r$ is the same for all colonies and Earth. It might not be!* ***Disclaimer:*** It's been a very long time since I had to deal with summations. I may have constructed that incorrectly. If you see an error, please either correct the answer or let me know in comments. Thanks! **Conclusion** So, based on Occam's Razor, we have an equation that would let you solve for the time required to exceed Mother Earth's population given... * We ignore anything and everything that could change Earth's population growth over the last 1,000+ years, * We ignore anything and everything that might modify population growth on colonies, * We ignore any consequence of space-born population, * We ignore the removal of Earth's population for the purpose of seeding space. * We ignore things I'm sure I haven't thought of. You've asked a simple question with a very complicated answer that requires us to ignore a whole lot of "what if?" So much so that I was seriously tempted to vote to close, but I thought the exercise might be valuable. --- 1 *If 2020 didn't convince you of that last assertion, then we have a problem. Using U.S. politics as a baseline and oversimplifying so much that angels weep, a liberal-optimist will believe humanity will eventually adopt zero population growth. A liberal-pessimist will believe violence is required to assure zero population growth. A conservative-optimist will believe in free-market-style population growth. A conservative-pessimist will believe in wiping out the liberals, and then free-market-style population growth. Where in that massive spectrum the future falls is an enormous guess that also makes angels weep.* 2 *In a non-political way.... See the previous footnote.* [Answer] A lot of this is about the 'R' number. Let's assume that all we had to concern ourselves with were basic questions of economy on the basis of limitless(!) space. Let's also assume that there were limitless resources (everything necessary for life) available within easy reach from anywhere within limitless(!) space. A conservative estimate (given unlimited space/resources) is about 50 years to double a human population. So, if we saw a net migration of 100,000 to space, and we provided ideal circumstances (but no forced breeding programme) it would take about 500 years to exceed the global population (assuming that the global population is stabilised due to limits of space and resources). [Answer] ### Unknown, because it requires technical advances we don't currently have We're going to have to assume Mars here, as the place which is currently most survivable long-term in our solar system. Gravity is close enough to Earth's that we're unlikely to have problems there. The Moon (at 1/6th G) is unproven safety-wise on that side of things, as well as being generally harder to work in vacuum. Once you get outside the [Van Allen belt](https://en.wikipedia.org/wiki/Van_Allen_radiation_belt), your radiation exposure goes *way* up. As described [here](https://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays), the radiation exposure on Mars is 10x the maximum permitted for DOE radiation workers. In transit, you're getting 30x the maximum. This greatly increases the risk of leukaemia and a number of other issues related to radiation exposure. Until we have viable and well-tested shielding abilities, we really don't know whether it's possible for humans to survive there long-term without major health issues. Of course we can (and do) send volunteers into high-rad, high-risk environments like the ISS for limited periods. A colony requires children though, and it would not be ethical to bring up children in an environment which is inevitably damaging to them. A common concern is that radiation exposure causes birth defects. This at least is largely disproved by [research following people exposed to the nuclear attacks on Hiroshima and Nagasaki](http://large.stanford.edu/courses/2013/ph241/yapa2/). Birth defects in children of [hibakusha](https://en.wikipedia.org/wiki/Hibakusha) were not statistically different from the regular population. However the same studies show a range of issues depending on the age of the survivors at the time of the bombing. It should be obvious that anyone growing up in an environment of continuous exposure would experience all of these. Some consideration of this has already happened - for example, there are suggestions that people might live in underground bunkers. This brings its own problems though, with all the health impacts (from mental health to eyesight) observed in prisons without regular outdoor time. Even for people who can tolerate long periods in confined spaces, there are simple physiological impacts on health which are unavoidable. Some of those (vitamin D deficiency from lack of sunlight) can be solved with dietary supplements, but some of them (atrophy of eye focussing muscles) can't be fixed so easily. Unless we have reliable methods to shield people from cosmic rays, and to ensure their long-term health inside whatever shielding structure, the answer to this has to be "not until then". This would all need to be thoroughly evaluated before anyone could consider having children there. ]
[Question] [ (**NO CIA/FBI/NSA IM NOT A TERRORIST ARMED WITH 250 STOLEN/UNACCOUNTED FOR NUKES**) I’m writing a Godzilla fanfiction and in it, while Godzilla was doing Godzilla things on the West Coast (destroying cities, fighting and brutally killing other Kaiju, forcing humanity towards extinction, etc.), the US was finally forced to deploy nuclear weapons against the gargantuan nuclear monster in an attempt to annihilate Godzilla (even though in my story Godzilla has historically easily and effortlessly tanked the Castle Bravo “test”, the Tsar Bomb “test”, the Vela Incident, etc.). This became infamously known as “**Operation Ragnorak**. Anyway, the US military was able to lure Godzilla into Owens Valley in eastern California and when the giant nuclear Kaiju was at the deepest point of the Valley, 250 nuclear weapons were launched directly at and within the direct vicinity of Godzilla himself (he survived obviously). Of the 250 nuclear weapons used against Godzilla, most of them were composed of W-87s, W-78s, W-88s, W-59s, and a few B-83s. They were all detonated in sequence, with most of them being deployed from land-based nuclear silos, ICBMs, nuclear submarines, and a few bomber-based aircraft (the first phase of Operation Ragnorak also utilized nuclear missiles that were turned into makeshift nuclear mines). But what would geologically and ecologically happen to not just Owens Valley but also the Southwestern US? What would be the direct result of detonating 250 nuclear weapons within a small, confined, narrow strip of land? And what ideal situation would occur where the US isn’t wiped out as a country but there’s still the mass deployment of nukes against Godzilla? [Answer] # Consequences Not Too Bad, Considering The average warhead in the US nuclear arsenal, dialed to full-yield, is 200kt. We'll assume that most of the weapons used approximate that. You *have* specified that a few of the big boys are being employed, though, so: [NukeMap of the consequences of a 1.2MT bomb in Owens Valley](https://nuclearsecrecy.com/nukemap/?t=73c9de83fc581af91048b3aecdae017a). The biggest of the bombs is going to throw fallout the highest, generate the most (as I assume no one is bothering with dirty bombs), and create the biggest fireball. Both the NukeMap and the rest of my estimations are assuming groundburst for all utilized weapons, as overpressure and area destruction is not the goal. So the fallout plume from the W83s extends well over mid-Nevada (ironically, not over the Nevada Testing Site!), but not really much further, and most of the plume would just require that people in the area take iodine supplements for a few weeks afterwards. Remediation of the rest of the fallout would be a process, but not too dramatic a process. Estimated fatalities from the biggest bombs in that location ~30, total injuries ~410. There would be a statistically measurable uptick of cancers globally, since 250 bombs would be more in-atmosphere detonations than the US has ever performed, and at substantially greater megatonnage. Nothing geologically would happen. Assuming the average of 200kt per bomb, 250 such bombs is only about 50MT. In comparison, Mt. St. Helens was a 24Mt detonation, all at *once*... and it didn't permanently do anything other than make the top of the mountain into a crater. You've got a bunch of sequential explosions. There'd be some weird cratered terrain at ground zero, and the nearby walls of of the valley would take a beating... and that's it. Ecologically, you'd be throwing up a fair amount of fallout, but even assuming no human remediation, this is still less than a tenth of the total megatonnage detonated on earth in the course of nuclear testing. The US would be barely affected, physically. Obviously, mentally, there'd be a lot of trauma. (Not to mention, an enormous number of questions lobbed at the military leaders who *kept using* nukes after it was apparent that they weren't working.) --- To compare, *Tsar Bomba*, which you namedropped, was about equal in yield to your entire attack. [Here's the island it was dropped on.](https://goo.gl/maps/b1vn9xrBS3QHGMkh9). You can see the scars, but if you weren't told that was where it happened, you wouldn't even know. Edit the second - I'm assuming that the *fact* that Godzilla survived both *Tsar Bomba* and *Castle Bravo* isn't broadly known or known at all to the targeteers whose job would be deploying the nuclear devices, or they wouldn't do it. The people responsible for initiating nuclear devices are very aware of what they're capable. [Answer] There's a chance your detonations could set off tectonic faults in Owens Valley. In 1872 there was an estimated 7.8-7.9 magnitude quake that killed 27 people, or 10% of the population in the valley. <https://en.wikipedia.org/wiki/1872_Owens_Valley_earthquake> The explosions might be enough to trigger the fault again, especially if Godzilla's route matched the fault. Here's an estimated map of the land offset from <https://seismo.berkeley.edu/blog/2019/03/26/today-in-earthquake-history-owens-valley-1872.html> [![enter image description here](https://i.stack.imgur.com/Oh7BG.png)](https://i.stack.imgur.com/Oh7BG.png) Imagine the plot value of Godzilla walking a line of nuclear attacks, to succumb to an earthquake triggered by those quakes. Perhaps the fault separates, drops him in, and then closes [Answer] ### Maximise collateral damage by creating an earthquake The military aren't entirely stupid. They've recognised that just dropping a nuke on Godzilla isn't going to work, and even a succession of nukes might not do it. So in the face of opposition which their weapons can't hurt, they have to go lateral. And with the extinction-level threat that Godzilla represents, there's basically no upper limit on collateral damage that can't be justified. The West Coast is famously full of tectonic fault lines. A solid earthquake has more energy than any nuke, and (as previously noted in another answer) the Mount St Helens eruption put out more energy than the entire US nuclear arsenal. So some modern-day [Barnes Wallis](https://en.wikipedia.org/wiki/Barnes_Wallis) suggests, "Can we blow through the crust, drop the kaiju in the hole, and have it crushed to death in the resulting earthquake?" (Top tip, by the way: Never underestimate the ability of the Brits to put a fuck-ton of explosives to good use. We may talk fancy, but we're a nation of complete nutjobs.) This isn't even hypothetical, by the way. US underground nuclear testing [has already triggered faultline movement](https://en.wikipedia.org/wiki/Operation_Crosstie), ironically enough in a test called *Faultless*. So we absolutely know it can be done. The only question is exactly what size of bomb you need to make it happen, which thankfully is something no country has experimented with. Yet. Enter the [nuclear bunker buster](https://en.wikipedia.org/wiki/Nuclear_bunker_buster). There are still plenty in the US stores, and I wouldn't bet against some researchers still working on new versions somewhere in real life, never mind for fictional plot purposes. For best results, it seems likely that they wouldn't actually aim at Godzilla. Instead they'd land multiple nukes along the faultline, fuzed to detonate at exactly the same time (and with modern electronics, "exactly the same time" can be accurate to the microsecond). You naturally want a delayed fuze anyway to explode underground. And you just make sure Godzilla is in the middle of the faultline when you do it. The outcome? Basically a really, ***really*** big hole. ### The hole truth How big? In Britain, the bombing range used to test [Tallboy bombs](https://en.wikipedia.org/wiki/Tallboy_(bomb)), the original Barnes Wallis bunker-busters, [still exists and is part of a National Park](https://newforestguide.uk/history/new-forest-explosives/ashley-walk-bombing-range/). (Yes, the village next door is called Sandy Balls. Also don't underestimate the ability of the Brits when it comes to comedy names for places.) From a 5-ton bomb, the crater was 130ft in diameter and 70ft deep. The [W88](https://en.wikipedia.org/wiki/W88) nuclear bunker-buster for comparison is roughly 95,000 times bigger at 475 kilotons. Let's assume the 5-ton Tallboy produced a 65ft-radius hemispherical hole, and assume volume "excavated" scales with payload - that gives you 3000ft-radius holes. 6000ft wide, 3000ft deep. Let's round down and say the hole is a mile wide and a half-mile deep. According to Google Maps, Owens Valley is around 4 miles wide. 4 bunker busters in a row would then basically guarantee you a hole the width of the valley. And half a mile deep, of course. How many W88s do we have? Wikipedia says "~400". Let's assume 200 for the OP's question. Suitably spaced, that gets us a hole 4 miles wide, 50 miles long, and half a mile deep. That's probably going to kick off some very interesting tectonic effects, for sure. And Godzilla is going to be one severely pissed off kaiju. ### About that collateral damage... It also gives you 54.6 billion cubic feet of soil thrown into the air per bomb. For 200 bombs, that's 22 trillion cubic feet, or 74 cubic miles. For comparison, [Krakatoa](https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa) only managed to spit out around 12 cubic miles of volcanic ash, and it did significant damage to the world's agriculture for several years. That soil is also going to be highly radioactive - I wouldn't even like to guess at the outcome there, considering Chernobyl put relatively little fallout into the air with rather significant long-term effects. The nuclear fallout is only the start though. The whole idea of this is to create tectonic effects. If we suppose that this does actually result in an man-made volcano, the end result could be even worse - and what gets thrown up by the volcano isn't just going to be volcanic dust, it's going to be heavily-irradiated volcanic dust. You can most likely say goodbye to California for human habitation for quite some time; but it could quite easily scale up to [*On The Beach*](https://en.wikipedia.org/wiki/On_the_Beach_(novel)) levels of worse. In short, pretty much any level of outcome that fits with your plot can be believably thrown into this scenario, up to and including the end of humanity. And that's before you remember that you still have to deal with Godzilla. *(Edit: I'd managed to misquote the W88 as 475 tons, not 475 kilotons, when I did my sums. With the correct value, this becomes truly apocalyptic.)* [Answer] The answers about tectonic activity seem to me to be totally unmoored from any scientific basis. It's true that the energy scales for earthquakes and nuclear weapons are comparable. For example, a Richter 7 quake is the equivalent of about half a megaton of TNT. However, both an earthquake and a bomb are highly localized releases of energy. Seismic energy will radiate out in all directions, with the energy density falling off like 1/r^2 for longitudinal waves and 1/r for transverse (surface) waves. There is no reason to imagine that this energy would be focused in such a way as to make a fault slip or something. Jdunlop beat me to it with the nukemap simulation of fallout. However, note that the simulation just assumes some direction for the wind, and the direction it assumed was the least harmful one possible. If it's blowing toward SF or LA, there's a problem. Depending on various factors, this might set off catastrophic wildfires in the Sierra. The amount of ash released might be enough to have serious consequences, like a miniature nuclear winter. Agriculture in California might be stopped for years. LA is dependent on the Owens Valley for a lot of its water, and there are serious concerns about how the water pipelines would likely fail in a big earthquake. Even if the water kept flowing, I'm not sure Angelenos would want to drink it. General disruption of society and the economy would presumably be worse than, e.g., Hurricane Katrina. If trucks stop rolling into LA, people are going to starve to death. [Answer] **THIS WOULDN'T JUST HAVE EFFECTS ON THE LAND, IT WOULD HAVE EFFECTS ON GODZILLA** As seen in Godzilla; King of the Monsters, Godzilla is powered by nuclear energy. A nuke blowing up in his face actually made him stronger, after it healed his crippling wounds in a matter of moments. If he was at full strength and at ground zero of 250+ nuclear detonations... Well, we've seen what happens when Godzilla goes 'super-critical'; he becomes so radioactive he melts metals that are near him, and he got there WITHOUT the help of a few hundred nukes. That much ordinance launched at Godzilla would push him WAY beyond the 'super-critical' state seen in the above movie. The upshot of all this? Not only would the nukes irradiate the valley in question forever, but it would also make Godzilla a billion times more powerful and possibly reduce the entire state of California, and a sizeable chunk of the neighboring states, to a gigantic pot of molten, radioactive slag as a result. ]
[Question] [ Our main characters have just arrived at the brand new SpaceStation2™ (now with geostationary orbit!) soon they get settled in with the other characters already there, then the planet explodes, no particular reason why, just blows up with the average velocity of a chunk being 9km per second (deviating up to 5kmps more or less) in the general direction of away from where earth used to be. Obviously a chunk hitting the station would be bad, and so would some other things, but could it survive? important stuff: * 3x the size of the ISS currently * the station can have whatever modules or supplies is necessary for its survival within reason * the crew is 16 people * assume crew can be specialized in whatever is needed * there are 2 crew dragons docked and 1 cargo dragon * assume they can grow enough food to survive using SuperPlantX™ * take into account survival for 1st month * survival requires at least 14 people remaining at the end of the month * survival requires at least 90% of ship to be intact and no major issues So, can they survive? [Answer] ### Your death star blast is so weak that they wont notice it. 9km/s is below the 11.1km/s you need to break out of Earths gravity well. All those chunks are going up, slowing down, and coalescing back and reforming a new planet from the same parts. They're in geostationary orbit (35,786 kilometres above equator) Earth explodes at 9km/s in all directions. Those chunks travel "upwards", reaching a maximum height of about 4,200km above the old surface, before reforming. They'll wake up one morning, notice the internet is down, scratch their heads, look out the window, and notice Earth has become a ball of fire and lava and steam and ash clouds. When the ash settles and lava cools, they'll notice the continents have been shuffled. --- Edit: After I posted this you added the 5kmps standard deviation. Meaning back or envelope about 40% of the mass escapes (but I suspect it will be much lower I'll explain below). it's reasonable to assume that the mass that escapes will be the smaller end of the chunk size spectrum, and overrepresents the crust and atmosphere. These chunks will be decelerated significantly by the climb, friction with the former atmosphere, and collisions with other chunks. The pull of gravity will decay over the few hours it takes for the chunks to reach the space station (as less mass is below each chunk), this will cause the outer chunks to be decelerated more than the inner chunks, creating secondary collisions, reducing the chunk size further, and turning kinetic energy into heat. This slows down the chunks significantly. With zero play between them you're looking at 0 - 3kmps impact speed for particles within 1 stddev. With secondary impacts, I'm guessing those parts of the crust that reach geostationary will be ground to dust / pebbles and moving 0-2kmps. Under these modified conditions, your space station will probably get hit with hot gasses travelling at hypersonic speeds (remains of atmosphere, greatly reduced in density - the 2-3 stddev cases), then covered in dust on the underside with small particles (remains of fastest moving crust chunks), then hit with small pebbles travelling at about 1-2kmps. These will ding the hull, may be enough to breach weak sections and damage solar and radiators, but if crew quarters are not against the bottom wall, and no breaches or critical damage occurs, they still may not notice it immediately. This does add a heat problem however, those hot gasses heated the ship. If the system is automatic and radiates heat into space automatically and has sufficient capacity they'll be alright. The iss has excess capacity to allow experiments and heat producing tasks. When they look out of the window in the morning they will know what has happened - airborne chunks of planet will still be airborne, chunks of rock below them are slowly starting to fall back towards the planet. ### But what if we add more power? If you add a zero to the velocity of the chunks - big chunks go very high. If big chunks miss them, they'll transition into a solar orbit along with some of the debris - which could be very nice stable orbit or chaotic elliptical depending on exact time of day the planet blew. If they're self sufficient for food, water, and power, they could survive until they run out of spare parts for critical systems and their jerry-rigs fail. If stocked with enough spare parts or decent 3D printers, they might die of old age, perhaps even raise a second generation. The rest of their life will be spent avoiding orbital debris of Earth in adjacent solar orbits. [Answer] My answer to this question: [https://worldbuilding.stackexchange.com/questions/151398/aliens-blew-up-pluto-so-we-would-stop-debating-whether-or-not-to-call-it-a-plane[1]](https://worldbuilding.stackexchange.com/questions/151398/aliens-blew-up-pluto-so-we-would-stop-debating-whether-or-not-to-call-it-a-plane%5B1%5D) Discusses whether Earth life would survive if Pluto was exploded. As you can see, I tend to believe in the Endor Holocaust. I may note that Pluto has a mass of 0.00218 Earth, so Earth is 458.7155963 times as massive as Pluto. Geostationary orbit is 35,786 kilometers above the equator. One Astronomical Unit or AU is 149,597,870.7 kilometers. Earth is 1 AU from the Sun, and Pluto is between 29.658 and 49.305 AU from the Sun, so the distance between Earth and Pluto varies between 28.658 and 50.305 AU. Taking the closest distance between Earth and Pluto for comparison, that would be about 4,287,175,779 kilometers, which is about 119,800.3627 times geostationary orbit at 35,786 kilometers. The density of an expanding debris field should decrease with the cube of the distance, so when the debris from Earth reaches geostationary orbit it should be about 119,800 cubed times as dense as the degris from Pluto in my answer. So the debris from Earth reaching geostationary orbit should be about 1,719,374,300,000,000 times as dense as the debris from Pluto in my answer to: [https://worldbuilding.stackexchange.com/questions/151398/aliens-blew-up-pluto-so-we-would-stop-debating-whether-or-not-to-call-it-a-plane[1]](https://worldbuilding.stackexchange.com/questions/151398/aliens-blew-up-pluto-so-we-would-stop-debating-whether-or-not-to-call-it-a-plane%5B1%5D) And thus it should be much more likely to damage the space station in geostationary orbit. Space stations in low Earth orbit are slowed by the extremely thin atmosphere hundreds of kilometers above the surface of Earth and slowly descend from their orbits, and so have to sometimes uses thrusters to boost themselves to higher orbits. And it seems very, very, very probable to me that the explosion of Earth will move gases up to geostationary orbit which will be at least as dense as Earth's atmopshere in low Earth orbit. Thus the space station will slowly descend into regions were the gas is denser and will slow and descend faster and faster until it eventually crashes into the red hot surface of Earth. And it seems quite possible to me that the exploding Earth will produce a gas layer at geostationary orbit which will be at least as dense as the atomsophere at the surface of the Earth. Ignoring whatever velocity that gas will have, a space station in geostationary orbit would have an orbital speed of 3.0746 kilometers per second. Running into gas with a density similar to sea level atmospheric pressure would be the equivalent of encountering sea level winds with a speed of 3.0746 kilometers per second, or 11,068.56 kilometers per hour. And the space station would quickly heat up and vaporize like space junk reentering Earth's atmopshere. Ash's answer says that the specified average velocity of Earth chunks of 9 kilometers per second would be less than the necessary escape velocity of 11.186 kilometers per second, and so the Earth maderial would mostly fall back to Earth. But there should be a wide range of velocities of Earth pieces, so that a significant percentage of them would be travelling at least 11.186 kilometers per second and thus eventually reach and pass geostatioary orbit. So the space station at geostationary orbit should encounter a significant density of gas and plasma particles. Topcode said in a comment to his question that the material should deviate by 5 kilometers per second from the average speed of 9 kilometers per second. Thus the speed range would be between 4 kilometers per second and 14 kilometers per second and some of Earth's mass would definitately reach and pass geostationary orbit. I note that at geostationary orbit the Earth should have an angular diameter of about about 33.80 degress, about 67.6 times the angular diameter of the Sun, and thus its surface would cover about 4,569.76 times the amount of the sky that the Sun did. So if the space station received only 1/4569.76 as much energy from every square arc second of the Earth's surface as it received from each square arc second of the Sun's surface, it would receive as much energy from the Earth as it received from the Sun. Which would eventually overload the space station's cooling systems and everyone would die from the heat. And the Earth would have just been exploded and many of the chunks would have eventually fallen back onto the Earth, and Earth would be red hot lava radiating a lot of energy into space, possibly for millennia. [Answer] in a short term, I think so. in a long term... no. here is my view of your scenario. if the space station is very modern, areas should be able to be closed off and hereby saving the crew. but there will die slowly for what I can see. because; 1. they have lost their planet. meaning no place to go and no new way of getting oxygen, food, or fuel to the spaceship. 2. the food will only let them live for so long. even if only half of the crew survives. 3. I am pretty sure they will lose oxygen before food, but I am no expert so that this with a gram of salt. if they are going somehow survive. they either need to find another spaceship or get back to the planet of hope for the best there. those are the only scenes I can possibly see them survive in the long run. [Answer] **Most likely.** I don't see why they shouldn't. Resupply runs for the ISS are less frequent then every month ([see here](https://en.wikipedia.org/wiki/Uncrewed_spaceflights_to_the_International_Space_Station)). Given that ISS doesn't have this revolutionary SuperPlantX™, your SS (not the best abbreviation) would last quite a while. The other thing is being hit by Earth chunks. In that case, it all really depends on where the chunks hit and how big they are. [Answer] With speed of 9km/s, and deviation of +-5km/s on top of that, only about 2%-5% will get as high as your GEO station. And it will be moving at only about 1km/s when it passes the orbit. Your station is 3x the size of the current ISS. So about 300m diameter. Surface area about 70000m2 Total 'surface' of GEO sphere = 7.44×10^17m2 So only about 1 part in 10^13 of the ejecta that passes GEO, hits you. Total mass that passes by GEO distance = 5% of Earth mass 5,972 × 10^24 kg = 2.986 x 10^23kg 1 part in 10^13 of this is 2.986e+10 Your spacestation is HIT BY 29.86 ***MILLION*** TONS of debris, moving at about the speed of an anti-tank cannon projectile. ***NO, you would not survive that!*** [Answer] I'll take a look at it from after the survival of the initial explosion (by whatever means). The biggest question here is how much of the earth's mass is intact? It is the earth's mass that kept the station in orbit. Even if the earth didn't lose all its mass, the station would be set adrift (not even considering any forces like expanding gasses pushing it away). Not tied to the earth, the station would also not be tied to the sun. The station will eventually exit the solar system. Based on trajectory, it could be out of the solar disc quite quickly. The station could be exiting at speeds exceeding 1,000 mph an estimate based on earth's rotation. The current space station is not in geostationary orbit and moves at 17,500 mph (28,000 km/h). Alternatively, it could be headed into the sun! To my knowledge, stations are better at being stationary than stellar propulsion. ]
[Question] [ Many animals have the ability to see polarized light (or rather, are sensitive to the direction of polarization), [most notably birds and bees but also a wide range of other animals including cephalopods, many arthropods, and some vertebrates](https://en.wikipedia.org/wiki/Rayleigh_sky_model#Navigation). Several of these species are thought to navigate by using the polarization patterns [to determine the exact location of the sun, and use that as a compass to navigate](https://royalsocietypublishing.org/doi/10.1098/rstb.2013.0037). Some species are even capable of detecting polarized light in night conditions, thought exactly how is still controversial. [Depictions of how these animals see polarized light (as well as mock-up devices intended to mimic this effect for human eyes) show the direction of polarization as banded patterns visible on the sky](https://www.newscientist.com/article/mg21128261-700-crittervision-see-like-a-bee/). [Humans can see polarized light but we aren't that sensitive to it and can't use it to navigate like other animals can](https://theconversation.com/polarised-light-and-the-super-sense-you-didnt-know-you-had-44032). My question is this, given that these polarization patterns appear to be visible on the sky, would a sapient animal (that can therefore communicate what it sees) with the ability to see polarized light be able to identify the general orientation that a photograph or video had been taken from based on polarization patterns in the sky in the background? Or do most cameras not record that kind of information since the information being captured is intended for the human eye, which is more or less insensitive to polarized light? **EDIT:** As a clarification, what I mean is would an alien sensitive towards polarized light be able to determine the direction at which a photograph or video was taken based on a photograph taken on a camera built by and for humans (i.e., cameras seen in everyday life), rather than a special camera built by the aliens specifically to take pictures/video accurate to their polarization-sensitive vision [Answer] You can test this for yourself by looking at a normal photograph through a polarising filter and rotating the filter. Unfortunately, I'm certain you'll find this has no effect, neither on a digital photograph nor a film one. (Well, for some digital displays you might find the whole image fades in and out, or you see colour fringes from a coating on the screen, but these effects don't correspond to the polarisation of the original scene.) Existing cameras aren't designed to record polarisation, and our displays and printing processes aren't capable of reproducing it. I would guess that recording and reproducing light polarisation is at least as hard as recording and reproducing colour - which is to say, it could be done, but it wouldn't happen automatically, and it would take some effort to develop and implement the technology. A human camera could easily be modified to record polarisation in a crude way, for example by taking a few shots in quick succession while rotating a polarising filter in front of the lens. (As John Dvorak points out in the comments, a total of three shots will do the job.) In principle it should be possible to develop a polarisation-sensitive CCD or CMOS sensor, but it would take some R&D, unless such a thing already exists for use in scientific instruments. A display that accurately reproduces polarised light would also require some effort to develop, although a crude approximation might be possible by just combining several projectors, each with a polarising filter, as is done for 3D movies. As Matthew points out in the comments, three projectors should be enough, or possibly only two, depending on how the aliens' eyes actually detect polarised light. In short, as A. I. Breveleri's answer suggests, if the camera is designed by your aliens, it likely will record polarisation, just as our cameras record colours, but ordinary photos and movies don't include that information. [Answer] Humans and other people who cannot see polarization make and use cameras that do not record polarization. When cephalopods and other people who naturally see polarization use human cameras, they cannot see polarization in the photographs because human cameras do not record it. Cephalopods have a word, "isogris", analogous to the human's "monochrome", to describe such limited photos. Cephalopods are inspired to invent and produce cameras that capture *and reproduce* the polarization present when the photos are taken. Their finished developed photos emit polarized light. These photos look more natural to cephalopods, in the same way that color photos look more natural to humans. Humans using such cameras are not aware of the polarization emitted by the resultant photos. Humans who want to record polarization invent and produce cameras that capture polarization and *record it as color or brightness*, the way human monochrome cameras record colors as shades of gray. This is accomplished by adding a polarizing filter over the lens. Humans using such cameras see a representation of the polarization, usually as varying color saturation. There is no serious market among cephalopods for the inferior isogris human cameras. [Answer] @stephen-dadonna [wrote in a comment](https://worldbuilding.stackexchange.com/questions/177175/would-a-sapient-being-sensitive-to-polarized-light-be-able-to-see-the-angle-of-p#comment550551_177175): > > Not an answer so I'll just comment: Sometimes the sky looks a deeper shade of blue in photographs that were taken with a polarizing filter oriented in a particular way. Perhaps a creature might be able to deduce polarization through the depth of colors in the sky or in reflections from water or oil slicks, etc. > > > I think the situation might be exactly analogous to the situation we have in real life with binocular vision and stereoscopic photographs (a.k.a. stereograms). Humans evolved in a world where "judging the distance to a thing" was super important for survival. So we evolved binocular vision, which permits us to judge distance very well in the real world. But our camera technology is traditionally monocular — a photograph simulates the world as seen by a one-eyed person. Perhaps your polarization-sensitive creatures evolved in a world where "judging the degree of polarization of light emitted from a thing" was super important for survival. How could this be so? (I have no suggestions.) Can a human look at a flat photograph and "deduce" the Z-level of an object in it based on visual cues such as blurring, relative size, etc.? Sure. Of course, we're not 100% perfect at it. In fact there's a whole category of trick photography based on playing with this deduction — "Look, Aunt Betsy is on the same Z-level as the Tower of Pisa, and she's gigantic!" Perhaps your polarization-sensitive creatures would have similar "visual puns" based on perceived polarization, somehow. What survival value is there in being able to deduce Z-level from a monocular image, given that humans *already* possess binocular vision? Well, the skill becomes useful if you accidentally lose an eye — not *terribly* uncommon in the state of nature, I'd think. Similarly, humans are not-perfect-but-not-terrible at deducing color from a monochrome image; this skill is useful in twilight, when our visual apparatus becomes less sensitive to color but can still differentiate degrees of brightness pretty well. (However, for a counterexample, humans are *terrible* at deducing color from a monochrome image taken under light of a pure wavelength, e.g. sodium light. That's not a skill with much evolutionary heft behind it.) So, perhaps your polarization-sensitive creatures would develop "backup deductive abilities" to deduce polarization from color, if-and-only-if it was not uncommon for an individual to lose their polarization sense (say, through physical damage, or perhaps through illness or malnutrition). [Answer] *Maybe*... but probably not. It's *possible* that an animal that is "used" to seeing polarization would be able to infer this information from a reproduction that lacks it, based on other effects. This would probably depend highly on what was photographed. A human could conceivably be trained to recognize the same sorts of cues. However, as others have noted, human-designed cameras aren't designed to capture polarization information, nor are human-designed reproduction technologies generally concerned with reproducing polarization. Moreover, *accurate* reproduction of polarized light such as you are describing would be quite difficult. You *might*, with sufficiently advanced deposition techniques, be able to lay down pigments in a way that produces the desired polarization, however this a) may be sensitive to the illuminating light source, and b) will probably more closely resemble the sort of lithography process used to produce complex microchips (e.g. CPUs) than inkjet printing (*offset* printing is right out). As a result, they will either be very expensive, or your hypothetical sophonts will be *very* good at nanomanufacturing, which will have a significant impact on many areas of their technology. For *emmisive* displays, the situation is both better and worse. LCD technology leverages polarization in order to change the brightness of pixels. This means that pixel brightness and polarization direction, at least in a *human*-designed display, are directly coupled. The good news, however, is that I *think* you could replace the fixed polarization layer of a typical LCD with a second liquid crystal layer, which (in theory) would allow you to control the direction of polarization independent of the brightness. The same *should* be applicable to OLED displays, but note that you're going to be giving up a fair bit of brightness. As to making a device that can *capture* polarization... I'm not aware of any sensor that can record it directly. The two techniques that come to mind are to have a polarization equivalent of a Bayer filter, which will of course eat in to your effective resolution, or read the sensor multiple times with a different, uniform polarization filter in place. (A bespoke camera might incorporate a liquid crystal layer in front of the sensor for this purpose.) How do critters that can see polarization do it? Does biology have a solution, or does it "brute force" the problem as in one of my ideas? (AFAIK, biology detects color the same way as modern cameras, by having individual elements with different frequency responses; in effect, the Bayer filter is just copying from biology.) [Answer] This is not an answer, merely too much text for a comment. Sometimes this site sends me on fun research rabbit holes. A 2018 article talked about birefringent printing, that is, intentionally printing something with variable polarization. Have a look at <https://pubs.acs.org/doi/10.1021/acsami.8b14899> This leads me to think that all traditional printed photos would look flat to your aliens, with the reflected light partially polarized to the angle of the paper. You can buy polarization filters for screens, but that applies to the whole screen. It would all have the same flat look to your aliens. As for imaging something with polarization, one way is to take a picture with a filter, rotate the filter, and take another picture. This isn't ideal, because some time has passed, and some parallax may be introduced by minor shifting of the camera. What about putting two cameras side-by-side, different rotations, and imaging at the same time? This has a worse parallax problem. One group's solution in 2010 was to make a custom CCD with a checkerboard of filters, read each checkerboard square out. This would have to have very small checkerboard squares to look acceptable. With a similar output device, your aliens might be able to make a more lifelike screen. <https://www.researchgate.net/publication/47404085_CCD_polarization_imaging_sensor_with_aluminum_nanowire_optical_filters> [Answer] Polarization is a parameter of light, either when treated as a wave (with angle of polarization) or as photons (with polarization numbers). The reason you can't get polarization info from a photograph is that all this information is lost when the light is converted into electrons (in the case of solid-state sensors) or used to change molecular states (in the case of chemical film systems). All these cameras only report energy vs. position. It would be possible in theory to do something like replacing the RGBG filters on top of camera sensor pixels with a set of filters with different polarizations, such as vertical, horizontal, and circular. Then some careful processing could generate multiple images which, by their difference in intensity patterns, indicate the distribution of different polarizations in the input. For the purposes of SciFi, no reason an alien species couldn't have polarization-sensitive analogies to our color-cones in their retina. [Answer] # No-ish ***Edit:*** Rule #1: never pound out an answer in a short period of time. It's important to understand that how we think of light mathematically is quite a bit different from what light actually is in reality. "They're either like infinitely small bullets flying in straight lines, or they're like enormous expanding [3-dimensional] EM pond-ripples from a thrown pebble." ([William Beaty, 2004](http://amasci.com/miscon/coherenc.html).) Polarization is the perception of those "pond-ripples" on a single plane. When you look through a pair of polarized sunglasses (glasses that permit those "pond-ripples" through a narrow region of the 3-D pond (ideally a single 2-D plane, but I doubt the tech's anywhere near that good)1 you're only seeing the photons that happen to conform to the polarizing matrix of the lenses. You're seeing some ripples, but not most or even all. If you had a pair of glasses that were polarized to the same direction as your eyes, looking forward, but wrapped all the way around your head, you'd see the dark bands shown in your article about the bees. I'm unfamiliar with glasses designed this way, though, which is why no pair of polarized glasses I've used have produced the bands (I suspect they're designed such that the polarization reference is transverse to the plane of the lens and has nothing to do with which way your eyes are pointing). The important point here is that light, itself, is only "polarized" artificially. In nature (as with our sunglasses), the bees *eyes* are designed to accept light along polarized lines, therefore accepting light along specific planes of the proverbial 3-D pond. Why is this important? Because you appear to have not thought through the art of photography. People are rarely interested in taking an exact image of what they see (in fact, it's remarkably difficult to duplicate *exactly* what the eye sees). What they really want is something more idealized. In the professional/studio extreme this means that all shadows are controlled. The banding one of your articles refers to would be an undesirable distraction (like any other shadow we see today) that would be smoothed out with filters, diffractors, and all kinds of equipment. At the other end of the spectrum are cheap cameras and amateur photographers — but even these want to minimize the undesirable effects to get that "ideal shot." Finally, the photograph itself is reflecting light that's being perceived through polarized lenses. But the reflected light cannot reflect what the photograph depicts. If the camera has a polarized lens, it will show the kind of data you want to see — but the art of photography is to remove as much of that as possible. Therefore, you need to make a choice. Do your characters *want* to see that polarized effect in their photographs or not? Do they, like we do ourselves, want all the distracting and extraneous shadows removed, to get the "perfect shot," or do they want something that's as close to what the eye sees as possible? (Which would be completely contrary to what we want to do today... please keep that very much in mind. It has nothing to do with whether or not we have polarized lenses.) If they want the "perfect shot," your characters will be no more able to deduce things like the angle of light than we are today. (And we do analyze it. Forensics looks closely at imperfections like that to do exactly what you're thinking of.) If they want "true to my eye" pictures, then they could deduce that kind of information. Choose. --- 1 *Or the exclusion of some of the infinitely small bullets, it depends on whether you want to think of them as particles or waves. In relation to this discussion, it doesn't really matter which you choose. I chose the pond metaphor.* ]
[Question] [ Synthetic Mana is a form of artificially created energy that is used for various purposes, such as power sources, fuel, etc. These substances can be made in large quantities and stored away for many years in prime condition. What it has in quantity, it lacks in quality compared to natural Mana found in humans. Natural Mana is ten times purer and richer, making it vastly superior to the artificial version. Unfortunately, humans possess a limited supply of it, and extracting it is dangerous to them. I am a young entrepreneur who has developed a scheme for securing high quality Mana. As extracting it from humans is illegal, I have begun targeting the more deplorable groups of society to allay suspicion. You know, the typical useless dregs who produce nothing of value and wouldn't be missed: liberals and illegal immigrants. In the case of the latter, my method involves attracting these people through advertisements to my country with the promise of work and eventually a green card. As they become settled, they will send for others (wives, husband's, children, etc). At some point, I will murder the families, extracting their Mana through a dark ritual, and dispose of the bodies in a crematorium to remove the evidence. As they were undocumented, it would appear as they never existed, making my plan foolproof. Unfortunately, I have discovered that high quality mana is difficult to contain and store, making it more expensive to secure. Even after I have managed it, it tends to dissipate quickly, only lasting a few months at best. I am essentially spending more money for a product that lasts for a shorter timeframe, making this a failed investment. How can this be the case? [Answer] **Mana can only be properly contained withing a living, organic receptacle.** Taking a look at these people, despite absolutely worthless to the point one wouldn't ever know if they were to disappear, their mana stays within them so well, better than any other container, and the same can be said for those with higher levels of mana. But there's essentially one similarity between them all: living, organic tissue. It's easy to see that mana stays very well contained and non-reactive inside living tissue. Maybe due to the oxigenated tissues, maybe due to special signals from the nervous system, perhaps even to some other binding agent current magic science is uncapable of detecting. The point is that Mana requires living tissue to remain truly stable, starting to dissipate naturally once it leaves the body. It doesn't immediately becomes unstable and reacts with the environment around it (that'd be rather troublesome for the mage who use it all the time), but it starts to disintegrate nonetheless, similar to the [half life process of radioactive atoms](https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/11%3A_Nuclear_Chemistry/11.2%3A_Half-Life). That means that, you'll need to somehow create and mass produce artificial beings capable of working as living containment units; being responsible for absorbing, stabilizing and storing this natural mana inside themselves, releasing it again whenever needed. Otherwise, this business is likely be bound to fail due to mana having too short of a half-life once outside one's body. [Answer] Like many chemicals the purest form of mana is highly reactive. Think of hydrogen peroxide or acids: you hardly find them pure, rather diluted in some solution. Or think of neutrons outside an atomic nucleus. They are unstable. A similar concept can be applied to mana. When it's too pure it's highly unstable and thus bound to either destroy its container or degrade. [Answer] It's haunted! Mana, obviously, is a mixture of the life force and psychic energy of the beings it came from. Laymen think it's a piece of their soul, which obviously is just superstition. Nevertheless, it contains an imprint of the will of the being it came from. Artificial mana is high in life force and low in psychic energy, because it is made by simulating ritual murder on a fermentation tank full of yeast. Fungi are quite lively but have no willpower whatsoever. This makes the artificial mana less powerful, as it is poor at powering any magical device that manipulates psychic energy such as mesmerists' wands, etc, and completely unsuitable for powering artificially intelligent agents such as golems, imps, sprites, etc. The advantage of artificial mana, other than being cheap, legal and easy to procure, is that it will never make an escape attempt more complex than bubbling over the rim of a beaker, nor will devices powered by it try to act out vague memories of the dreams of the men it was taken from if left unused for too long. As a compromise between the two, natural mana can be blended, so that no individual's will is discernable. This makes it easier to handle, as it no longer has coherent desires beyond the basic drives common to all men, but any imp powered by the resulting mana will have the personality of a block of Velveeta and be unsuitable for complex tasks. [Answer] What is mana? It might be : * A divine spark, * Psychic energy, * or some alternate form of undiscovered physical energy. **If mana is psychic energy**, the problem might be your choice of degenerates as a source. There might be an as-yet-undocumented quality of personal character that effects how rapidly mana becomes decoherent. History provides plenty of anecdotal evidence that great people of awesome personal character leave psychic marks that last generations after them. And, additionally, many people of poor personal character are barely remembered at their funerals, their psychic mark fades so quickly. In that case, selectively pooling "degenerates" for harvesting has given you a pool of product that depreciates in the tank much more quickly than your competitor's. **If mana is divine spark** (and maybe if it's psychic energy too) your method of collection may be causing the problem. Divine will might be that mana is given only willingly. Harvesting by force may damage the divine spark, causing it's accelerated rot. Or, as psychic energy, the attitude of the psyche involved provides stability (if given willingly) or instability (if taken by force) to the product collected in the tank. Or, perhaps, both factors play a smaller part, but are compounding in this particular case because you're doing both: harvesting barely-coherent mana in the first place, and damaging that mana during the harvesting process. **If mana is a new kind of chemical energy** then the spoilage problem could be related to the high concentration of mana itself. At higher purities, mana may engage in side reactions that spoil it. Or, natural mana may possess impurities that are caught in the harvesting process. These impurities may cause a kind-of fermentation, again ruining the product. [Answer] The difference between Synthetic Mana and Natural Mana is similar to the difference between the following two groups of food. * Fresh meat, baked bread, fresh grapes, and milk. * Jerky, hard tack, raisins, and water. You can survive on the second, but the first is generally a better quality meal. The second has the advantage that it will last a significantly longer amount of time before going bad. [Answer] **natural mana is chaotic** A fundamental rule of nature is that it is a world of strife and conflict. Primal forces wax and wane in strength, but remain truly unreliable. In every living thing is a small reactor of unpredictability, entropy incarnate. It's in mankind, too, but in such great quantities. A wolf might be hungry or lonely, but it's man that *hates*. Natural mana builds to such a fury, that it is only through willpower that we can manage to control it. Some don't, and let themselves be taken over by their insecurities, jealousy, and the chaos of their mana. To make something in a laboratory you must know it in its entirety. You must understand it fully and completely. A lab is a **controlled** environment. It is a place of worship for the religion of order. It is a place where you follow the rules, double-check your numbers, and if ever you find yourself *hoping* for the right outcome you've already made a mistake. Creating something fundamentally chaotic in a controlled environment could never possibility yield the legit thing. It is neutered, made a shadow of itself. This would-be imitation of something you might have laughably called "chaotic" is not hard to contain. Containing the metaphysical avatar of chaos, that's quite a challenge. [Answer] Mana accumulated in humans is the result of consciousness and the exertion of will and the presence of sophisticated ego. This is the most primitive form of magic - believing 'I am me' many many times over a life causes a mana-body to accrete overlayed with the physical body. Perhaps in addition to will (the method), mana must be acquired somehow such as by having a metabolism as [ProjectApex](https://worldbuilding.stackexchange.com/users/73198/projectapex) notes above. Even non-mages maintain a mana-based self-image that can be linked to phenomena such as the placebo effect, auras, phantom limbs, etc. Once the human will is removed, the mana-body is no longer maintained and begins to lose integrity and dissipates into the background noise. Inspiration: <https://en.wikipedia.org/wiki/Caddisfly#Cases> Possible Consequences: * Sometimes the mana-body is complex enough to briefly attain sentience and cause trouble before it fades away, or learns how to feed... + Perhaps your mana is not gone, they ate each other or escaped to hunt. * The mana-body may be readable before it dissipates, allowing fragments of memory to be collected from the recently dead. Given this theory, a longer term nefarious plan may be to locate/create individuals with a fractured or warped sense of self. It may be possible to cleave-off parts of their mana-body which might? regrow. A talented entrepreneur will be able to cope with the side-effects I'm sure... [Answer] Wavelengths. Natural mana exists in a whole spectrum. Artificial mana has a fixed number of wavelengths that give it the same coverage as natural mana, the same usage, but its efficiency is lacking. Current storage methods hold in many wavelengths, including all those within artificial mana, but it cannot properly contain natural mana. [Answer] "Mana" is actually the name of a class of substances, much like "fuel" is. Just as there are different types of fuel having different properties, so there are different types of mana. In fact, it is possible to synthesize the so-called "natural mana", but it's *really* not a good idea because it is so energetic. Humans can naturally produce small amounts of it relatively safely, because even the most energetic material will not cause damage if there is barely any of it to release that energy. But once it's in a quantity large enough for any commercial use - the slightest shock will make a crater where your storage facility once was. Even if you can store it safely, the risk that it will damage whatever you intend to use it with is just too high. There are analogues in the real world: [chlorine trifluoride](https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time) is one. It was used as an experimental rocket fuel until it was deemed too dangerous, being "hypergolic (sponateously combusting) with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water - with which it reacts explosively" and which is such a strong oxidizer it will burn things that are already burned. There are also things like [dioxygen difluoride](https://blogs.sciencemag.org/pipeline/archives/2010/02/23/things_i_wont_work_with_dioxygen_difluoride), often named "FOOF" because that's the noise it makes when it explodes in your face; and [azidoazide azides](https://blogs.sciencemag.org/pipeline/archives/2013/01/09/things_i_wont_work_with_azidoazide_azides_more_or_less), which will explode when you put it in an IR spectometer. For non-chemical reactions, radioctive material is safe (for some value of "safe") in small enough amounts but deadly in larger ones, as Harry Daghlian and Louis Slotin found out with the [demon core](https://en.wikipedia.org/wiki/Demon_core). ]
[Question] [ I'm thinking up a Mars or Venus type planet where the poles (or one pole) has a forest growing out of it due to a device that is used to make the planet more habitable by creating a oxygen friendly atmosphere. However the atmosphere has not spread throughout the planet so it has mostly aggregated at the pole due to the device being there. Possibly a river could also be flowing out of the pole. The poles are full of icecaps containing water similar to Mars, and the melting of the ice caps has caused the river to flow out. Along the riverside is where the human colonies would be staying. How feasible is this, and if not, does it tax suspension of disbelief too much? [Answer] The planet would have to be very hot such that only the poles are temperate enough to support a forest. That s because poles are always colder than the rest of the planet. The rest of the planet would be a scorching hot desert. Remove the part about the atmosphere not spreading everywhere as it makes no sense (it violates the 2nd law of thermodynamics). Since the rest of the planet is inhospitable you don't really need that anyways. A river flowing out of the pole is realistic, I don't see why that would be a problem. As you get further away from the poles, it would become thinner and eventually dissappear. So you would have a forest/arid/desert transition. [Answer] > > How feasible is this, and if not, does it tax suspension of disbelief too much? > > > Points that trigger the rise of an eyebrow: * > > the atmosphere has not spread throughout the planet so it has mostly aggregated at the pole > > > Gases have no intrinsic shape. To contain them into a given volume you need a container. Else they spread around following pressure and concentration gradient. * > > the poles (or one pole) has a forest growing out of it [...] The poles are full of icecaps. > > > You can barely have moss and lichens in a tundra environment. On icecaps you can simply forget about any vegetation, let alone a forest. If you want forests, forget about the icecaps. [Answer] Oxygen is a relatively light gas, and at 1 atm and room temperature the root-mean-square speed of each molecule is almost 2 kilometers per hour. If you are oxygenating a planet that already has a ~1 atm atmosphere, you will get a higher local concentration of oxygen around the device. If you are making an earthly atmosphere out of a near vacuum such as the martian atmosphere, you will only get breathable air after the whole planet has stabilized at a breathable pressure. If you do that from just one point at the pole you will either take millenia, or, if you do it fast (and bh fast I mean doing it in decades or centuries) you will have winds that will make colonization and forrests impossible. You'd have a better time seeding an atmosphere from multiple points in the planet. If you start with a venusian atmosphere, first you have to lower the pressure by ~89 atm. Good luck with that. Other than that, [the Earth itself has had a lushing forrest on the south pole, back when dinosaurs roamed the planet](https://www.bbc.com/news/science-environment-12378934). > > Go back 100 million years ago and Antarctica was covered in lush rainforests similar to those that exist in New Zealand today," said Dr Vanessa Bowman who works with Francis at the University of Leeds. > > > "We commonly find whole fossilised logs that must have come from really big trees." > > > I totally stole the link above from a comment for [another answer](https://worldbuilding.stackexchange.com/a/137236/21222). [Answer] Earth-like Desert planets are entirely feasible. In fact, [models have suggested](http://www.astrobio.net/news-exclusive/alien-life-more-likely-on-dune-planets/) that such a planet could enjoy a habitable zone that extends much closer to its host star than a more aqueous one could. Such a planet could be cold enough to possess ice-caps, but that will mean your deserts are also colder rather than hot. If you want forests at the poles, I'd suggest going with a hot desert planet instead. In that scenario, the majority of the planet is scorching inhospitable desert, and the poles possess temperate woodlands and marshes. Having a river flow away from the lush polar region and end in the desert is entirely plausible, and the suggestion of the [Okavango River](https://en.wikipedia.org/wiki/Okavango_River) as an example was a good one. As to keeping the breathable atmosphere restricted to the polar region, this could be achieved by having a significant change in elevation between the lush pole and the surrounding desert. If the pole lies in a [deep enough depression](https://en.wikipedia.org/wiki/Hellas_Planitia), it could harbour a dense, breathable atmosphere while the rest of the planet suffers from atmospheric pressure far too low to be breathable without assistance. Keep in mind that having the pole in a deep depression makes having a river flow out of it nigh impossible. ]
[Question] [ A few years ago I read a role-playing game supplement that described a cold war between kingdom Good and kingdom Bad. Both kingdoms used metal coins with silver as the most common followed by gold. Kingdom Bad planned to flood kingdom Good with gold coins, disrupting Good's economy in preparation for Bad's invasion. So far as I remember, Bad planned to use real gold coins and not counterfeit ones. To me it seems that all Bad is doing is emptying its coffers to fill Good's, essentially paying for Good's defenses, weapons, and mercenaries. However, I'm not sure if there's something I'm missing. Is this, in fact, really a reasonable plot? Can this style of economic warfare somehow destroy kingdom Good? The setting was low magic, high realism, high medieval Bad has about twice the population of good. Bad has spent vast amounts on their army but have a comparatively small navy. Good and Bad are separated by a narrow sea. [Answer] It depends on who has more gold/Wealth. If kingdom bad had much more wealth than kingdom good; then yes it is possible. Then there is also the issue of gold reserves. I am guessing both countries have access to gold mines. If kingdom Bad just discovered a huge deposit of gold then they can indeed pull off this strategy. In fact, there is an African king that had so much gold, he gave it away in the streets. [Richest person in history](https://www.businessinsider.com/mansa-musa-the-richest-person-in-history-2016-2) From the side of Kingdom good; they need to have some sort of central banking system to monitor inflation rates if they want to defend against such an act. They can find ways to slow down the influx. (Check purses at borders and confiscate coins) but ultimately gold coins are easy to hide. With that being said this is not a good strategy. Kingdom Bad can use the gold for their own troops, to hire mercenaries, hire assassins, bribe officials/ generals from kingdom good. Literally, any other strategy would be vastly better. [Answer] Yes, definitely, but it takes a lot of gold and a lot of time. Basically, when a country has a large, long-term influx of wealth, the wealth-generating part of the economy will tend to drive out everything else. This happened to the Spanish Empire in real life: New World gold and silver poured into Spain and Spain spent it. The part that was spent internally caused inflation. The part that was spent to buy imports drove domestic producers out of business. In time, all that wealth pouring in meant that Spain had a big colonial enterprise, but was deeply backwards in industry and trade. And that doomed the Spanish Empire. It's sometimes called the "Spanish Curse". There's a [question on the History Stack Exchange](https://history.stackexchange.com/questions/9060/how-did-the-gold-of-the-new-world-cause-the-spanish-empire-to-collapse) which deals with this in more detail. Actually, *any* resource that you just dig up (or steal from the people who dug it up) has the same effect if you get enough of it for long enough. (Oil-rich countries today suffer from the same problem.) The [Wikipedia article on the "Resource Curse"](https://en.wikipedia.org/wiki/Resource_curse) does a nice job discussing it. So if Bad has enough gold and is willing to pour it into Good for a generation or two, Good will be ripe for the plucking. [Answer] This is exactly what happened when Mansa Musa went on pilgrimage to Mecca From [Wikipedia](https://en.wikipedia.org/wiki/Musa_I_of_Mali) *Musa's journey was documented by several eyewitnesses along his route, who were in awe of his wealth and extensive procession, and records exist in a variety of sources, including journals, oral accounts, and histories. Musa is known to have visited the Mamluk sultan of Egypt, Al-Nasir Muhammad, in July 1324. However, Musa's generous actions inadvertently devastated the economies of the regions through which he passed. In the cities of Cairo, Medina, and Mecca, the sudden influx of gold devalued the metal for the next decade. Prices on goods and wares greatly inflated. To rectify the gold market, on his way back from Mecca, Musa borrowed all the gold he could carry from money-lenders in Cairo at high interest. This is the only time recorded in history that one man directly controlled the price of gold in the Mediterranean.* [Answer] It depends on how it's spend, and the culture of the good kingdom. There was a King in history who went to another country and spend a crapton of gold. This caused the value of gold in that country to go down and with the value of each coin tied to the value of gold it meant everything needed more coins to buy. 2 copper or whatever for a full bread before the gold came in? Now it costs 4 silver. The people who had sold stuff to the King and had gold didnt have too much problems with this, but anyone else would suddenly need to pay multitudes more without earning more or having more in reserve. Suppose the bad kingdom tries to exploit this: it pays specific groups of people money for wares and stuff, and ignores other groups. Just living becomes more expensive for everyone which will cause strife in the population. If the divide grows quickly enough and large enough people could revolt, destabilizing the country and making it an easier prey. While you are at it, buy specific goods. Buying weapons might not be the smartest move as the sellers could just have an easier time getting more weapons. Buying all the ore and resources to build weapons could deplete the good kingdom's resources while destabilizing the economy, and if you offer a higher price for the resources than good kingdom then the people who own the resources would gladly hold out and wait for a bad kingdom guy to come for their goods. Other resources to buy would be food, it might be the best choice. Buying food directly means more stockpiles for you, higher food prices for good kingdom coupled with massive inflation and less food for good kingdom to prosecute a war. Even better: if good kingdom tries to prosecute a war food prices will rise anyway on top of scarcity and inflation, it would probably kill the good kingdom the fastest. Lastly a risky option: pay the military of good kingdom. If you are rich the rewards of combat pay suddenly is a lot less motivation to risk your life. A portion of Soldiers of good kingdom might just leave when push comes to shove and try to be alive and spending somewhere. [Answer] As a short-term move, the Land of Bad might buy up some crucial resource, such as food, ores and even weapons, haul them out of the Land of Good—and then blockade it. Under ordinary circumstances, the Land of Good would now have a lot of gold and use that to import whatever it needs. But, while it’s under a military embargo, it can’t do that. It’s now facing a sudden and unexpected shortage of critical resources, and all it has is a bunch of useless gold that it can’t eat or fight with. The King of the Good had better have foreign allies and good credit. Although maybe the citizens of Bad will happily take gold and trade with the “enemy.” [Answer] You can play on exchange rates of gold and silver in respective countries. And yes, with a complication twist it happened before, see the [Opium Wars](https://en.wikipedia.org/wiki/Opium_Wars). Simplified, China was selling tea only for silver. When the cheap silver sources in Europe and European colonies was depleted, silver became more expensive (in gold), but China did not care. Hence, the driver of the Opium Wars. The basic scheme was: * let's buy opium in India for gold, cheaply * smuggle opium to China, either selling it for a lot of silver or exchanging it to tea directly * buy tea for cheaply acquired silver * bring back some (expensive) tea and (expensive) silver to the metropoles * sell them for gold. [Answer] Yes, imagine that gold represents something like the king's favour. There's limited gold, the king owns it all, and you need gold to pay your taxes. Thus you need to work for the king to get the gold you need to pay your taxes. If there's suddenly another source of gold, people no longer work for the king, etc. ]
[Question] [ The flying aircraft carrier has been in the imaginations of many a writer and engineer, but to date the only true flying aircraft carrier has been USS *Akron* (and to a lesser extent, her sister ship, the USS *Macon*). Neither lasted long enough to see war. In my story, however, the Evil Empire of XXXXXX is about to shatter the tense peace of an alternate, post WW1 Europe by a launching a surprise (or, to some, not so surprising) invasion of the continent. As required by all evil empires, they have constructed a superweapon. Key to their conquest is the use of a massive fleet of dirigibles (~50) designed to keep aircraft close to the front and right behind the empire's advancing armies. The main focus of their invasion is an mid-sized, neutral country that lies in between the alternate europe and the empire. Within this country are a massive array of helium mines with the potential to let the empire build limitless amounts of their flying dirigible aircraft carriers. Capture the mines, and the rest of the continent will bow to their war machine. Fail, and the war will slip from the empire's favor. But will it really? **With no later than 1931 tech, would the empire's dirigibles be an effective fighting platform?** Parameters: * dirigible design copies from the USS *Akron* * aircraft are similar to the F9C Sparrowhawks used by the USS *Akron*, but optimized beyond its real world application as a strict reconnaissance vehicle * the issue with weather has been ̶ i̶g̶n̶o̶r̶e̶d̶ resolved * in terms of fighting strength, the empire represents the axis powers circa WW1 * in terms of fighting strength, the neutral country at the center of the invasion is comparable to Belgium circa WW1 * air defense and weapon technology are also restricted to 1931 or earlier [Answer] > > helium mines > > > Helium is generally produced by extracting it from natural gas. There simply won't be any helium mines. But the biggest issue here is that you only need the helium for airships and they're simply not going to be used when competing technologies (aircraft) advanced and developed into more effective weapons systems. No helium mines in the first place, but no helium requirement anyway. The effort to generate Helium is also greater than the effort required to produce other materials. > > With no latter than 1931 tech, would the empire's dirigibles be an effective fighting platform? > > > No. Your problem is a simple one : the size of an airship required to support one fighter is enormous and all you get is an awkward, large, slow very attractive target for the enemy to focus on. Also keep in mind that [the first jet aircraft engine was developed in 1937](https://en.wikipedia.org/wiki/Heinkel_HeS_1) and patents had been filed in 1930 and serious design research papers in the later 1920s. The airship was essentially dead long before 1931. The absolute limit for an airship is one based on removing all the air and replacing it with a vacuum (nothing) - you can't get more buoyancy than that (ignoring the material required to contain this vacuum). That limit is [1.28 grammes of lift per *liter* of air removed](https://en.wikipedia.org/wiki/Vacuum_airship). So how heavy is a fighter aircraft ? Well it's one pilot at least, some fuel, bullets and a machine gun (or light cannon), wings, etc. A typical late WW1 fighter like a [Sopwith Camel](https://en.wikipedia.org/wiki/Sopwith_Camel) was about 420 kg empty and about 659 kg loaded. Let's be fair and day we need something like 750 kg per plane including pilot. That means for every plane we need some 586,000 liters of volume. That's a sphere of some 586 $m^3$ or about a sphere of 10 meters diameter or cube of about 8.4 meters side. For every plane ! And your FC9 Sparrowhawks were twice are heavy ! That means you need twice the volume which is some 25% extra per linear dimension. And that ignores the weight of engines, fuel, crew and compartments required by the airship itself. And on top of that you need recover the aircraft. That's *really* difficult. For a functioning aircraft carrier airship you need to be able to easily take off and land. You also need to be able to resupply the aircraft, which means lots of heavy fuel and ammo as well as replacement parts and some kind of maintenance deck. That's a real problem as these all add to the size and mass. And the larger it is the bigger the target it ! And airships are slow. Unlike sea based aircraft carriers they're hard to defend. You can't just surround them with a cordon of defensive ships. A gunner on the ground can take you out easily. Now Zeppelins could climb above anti-aircraft fire, but technology advances and if you are faced with a high flying enemy you will develop effective weapons to defeat them. **The alternative**. Aviation developed the way it did because there are easier solutions than airships that are more effective. Long range multiengine aircraft and the ability to carry drop-able fuel tanks to extent fighter range all proved effective in the long run. By WW2 these were the ways to go. So technology quickly overcomes the airship. Note in particular that if you're an attacking army wanting to deploy fighters and bombers forward as you advance, the technique is to either take over enemy airfields and airports or operate from fields and roads. Both these tactics have been used effectively. You don't need an airship, you need a supply chain to support your advance. You need cargo aircraft to resupply. And, again, aircraft rapidly developed to be better at this than airships. The further beyond 1931 tech you get the more the airplane technology becomes more effectives. Better wings, better engines, better materials, better fuel systems. The ability to build bigger multi-engined aircraft. Even better communications (radio) means you can use your force more effectively. Likewise the more advanced the technology for flight becomes, the more advanced the air defense technology becomes. Better fighters and anti-aircraft (and anti-airship) weapons will also be developed. This make slow moving and large targets like airships extremely vulnerable. Because they're also storing aircraft they're even more attractive targets and would be heavily attacked (just as aircraft carriers were in WW2). > > air defense and weapon technology are also restricted to 1931 or earlier > > > This is reality-check and that's not a realistic restriction. No one is going to restrict the development of these systems to allow airships to gain the upper hand. Quite the contrary. They're going to realize that they *need* these technologies to defend against airships. So rather that restricting develop, airship carriers would actually accelerate the development of these other technologies. [Answer] Another massive problem, apart from speed and vulnerability already mentioned (which are shared by ships acting as aircraft carriers to a large degree) is landing aircraft on the bloody thing. Both the USSR, UK, and USA experimented with airborne aircraft carriers and abandoned the idea as being impractical and too dangerous for the crews. The USSR even went so far as to test the concept in combat, fitting some heavy bombers with a number of small fighter aircraft during WW2 and using them as escorts for bomber attacks on German held positions, or to attack well defended targets with bombs where the larger bomber was deemed unlikely to penetrate the defenses. All experiments ran into the massive problems of getting the smaller aircraft back on board safely, using various forms of hooks and catching mechanisms. While they could work, they did depend heavily on extreme pilot skill, very calm winds, and incredible luck even under those conditions and more than a few attempts failed, resulting in crashed aircraft and dead pilots. As a result, all these experiments came to naught, and the few remaining prototypes were either scrapped, became museum pieces, or were converted to other duties. For one way missions, where landing back on the mother ship isn't planned, the concept can work. Launching a manned aircraft from another flying platform has been done successfully many times, it's pretty routine and no harder than launching a large missile (the main problem is keeping the pilot of the smaller aircraft happy during a potentially long transit to the launch area). Some wikipedia links giving ideas: [flying mother ships](https://en.wikipedia.org/wiki/Mother_ship) [flying aircraft carriers](https://en.wikipedia.org/wiki/Airborne_aircraft_carrier) [Answer] **Airships are *probably* not necessary to support 1910-style ground operations.** Armies still move at the speed of a walking soldier, or at best the speed of a truck on back country roads. The support elements of an aviation squadron should be able to keep up, leapfrog airbases close to the front. Every couple of days, the aircraft take off from one airbase and land at another closer to the front. **Airships *might* be necessary to support 1939-style ground operations with 1920s-style technology.** *Blitzkrieg* was not just about tanks. It was about highly mobile columns of all arms. Integration was not up to modern standards of combined arms, but it was understood that the infantry had to keep up with the tanks, and they couldn't do that by walking. But trying to implement *Blitzkrieg* with 1920s-era technology is going to run into problems. Radios are bulkier and less reliable. Tanks and trucks break down more often. And so on. One problem is that aircraft have lower speed and range. *Blitzkrieg* requires aircraft for tactical recon and tactical air support. Your flying aircraft carriers could help make recon available to the tip of the spear. However, it could be useful to have the aircraft available for recon, defensive counter-air, *and dive bombing*. A key element of the early *Blitzkrieg* successes was the Stuka with a responsive close air support doctrine. [Answer] By 1931 the [Schneider Trophy](https://en.wikipedia.org/wiki/Schneider_Trophy) was at its peak: the Supermarine 6 could fly at more than 500 km/h. With those speeds a dirigible is just an easy target floating mid air. I think they would not be such a formidable weapon: too slow to effectively support faster aircrafts, effectively hampering fast deployment of troops. [Answer] Doubtful - the *Akron*-class simply lacks the lifting capacity to carry an entire expeditionary squadron of fighters, once you add in the weight of fuel, ordnance, spare parts, pilots and mechanics, their water and food and lodging, etc. Remember that even the much larger *Graf Zeppelin* and *Hindenburg*-sized airships carried very small passenger loads on long-range trips. While their rather luxurious travel accomodations were heavy, the ammunition and fuel for expeditionary power projection and close air support are even heavier. Also remember that carriers are themselves targets, so a good strategy is to avoid being located by the enemy. However, that causes all kinds of fresh problems with precise navigation (especially when cloudy) and with secure, reliable, over-the-horizon communication between the carrier and the fighter group when the enemy does something unexpected. [Answer] > > With no latter than 1931 tech, would the empire's dirigibles be an > effective fighting platform? > > > Definitely no. Other answer already showed why they won't be such a good idea because of logistic reasons, unnecessary costs and unavoidable critical manouvres. The other main reason why they won't work is because they would have been an easy target for the 1931 state of the art: [550km/h planes](https://en.wikipedia.org/wiki/Schneider_Trophy#Winners) and [air-to-air rockets](https://en.wikipedia.org/wiki/RS-82_(rocket_family)). Someone might say that it's critical to aim something travelling at 500+km/h. Well, of course it's not easy, but the [stuka dive bombers](https://en.wikipedia.org/wiki/Junkers_Ju_87#Diving_procedure) were able to hit the target with a bomb, diving at 500-600km/h. In any case the difficulty is to produce something that can fly fast, not slow: if these airship aircarrier were used extensively and become a serious menace, the opposing force would have developed a "slow-enough" plane equipped with some big-caliber/slow-rate machineguns and/or dedicated explosives. I'd go with something similar to an [Hawker Hart Demon](https://en.wikipedia.org/wiki/Hawker_Hart#Demon), a '31 fighter/bomber, already equipped with Vickers machineguns. Since it's based on a bomber plane it won't have issues to carry some additional wheight (the aforementioned rockets). The speed is not an issue, it can cruise at 300km/h, therefore if needed (i doubt) it could easily reduce the speed to 200-250km/h and that's for sure a not-critical speed to aim something as big as the Akron. These rockets were able to shoot down fighters while launched by other fighters, it's just not reasonable to think that an Akron could be hard to be aimed at or could evade the rocket once launched in its direction. Not only, they have 6+km range, therefore they can be used "en masse" against an Akrons fleet, outranging other AA weapons, and they will hit something sooner or later. Obviously the Demons should be escorted by other, faster, fighter planes but they won't be an easy prey (they can still fight back). On the other side, if the Akron's fighters air superiority is not unbearable for the not-imperial air forces, the Akron's fleet will be a really easy target. Unless some fictional tech development they won't stand a chance, and that's why they were dismissed as air aricraft carrier (and as attacking vehicle in general). [Answer] I'm going to suggest an alternative to airships which also takes advantage of 1920-30 era technology: rockets. The chief reason to want a flying aircraft carrier is essentially to extend the range of the aircraft (particularly with the relatively weak engines of the period), but using rocket power provides many of the same benefits. JATO rocket assist for aircraft take off was used during WWII, but the essentially technology was developed much earlier (Robert Goddard, the German VfR group and the Russians all had vigorous experimentation on liquid and solid fuel rocket technology during this period). The Luftwaffe also was using rockets to boost training gliders into the air during the 1920's. [![enter image description here](https://i.stack.imgur.com/Zcqyh.jpg)](https://i.stack.imgur.com/Zcqyh.jpg) *It actually took America until 1941 to develop JATO assist* The advantages of rocket assist are allowing the aircraft to take off with a shorter runway, or alternatively take off with a much heavier payload or fuel tanks. The short field performance will allow tactical aircraft to be based in unexpected places to support the advancing army, while the ability to take off at the maximum take off weight provides the ability to maximize range or bomb/cargo load for bombers and transport aircraft. Delivering a large transport plane full of food and ammunition to a leading column can certainly give the ground commander much more flexibility and provide unexpected problems to the defenders. All these advantages require little modification to the aircraft of your force (essentially some internal strengthening of the fuselage and wings, and some modification to the landing gear to handle the extra stress), and once JATO assist becomes common, aircraft designers will make allowance in their designs for this. If you want to provide a real "Rocketpunk" flavour to the setting, aircraft could be designed to actually take off as rockets, and unfold wings at the top of a ballistic arc, while engines and propellers will be designed much like "assisted gliders", which start and stop the engine in flight according to need, and have propellers which fold away to minimize drag when not in use. [![enter image description here](https://i.stack.imgur.com/lYp4X.jpg)](https://i.stack.imgur.com/lYp4X.jpg) *Stemme S-10 in flight with propeller extended. When the engine is stopped, the propeller is retracted behind the spinner cone. Imagine this taking off under rocket power and swinging the wings out and starting the engine for a "rocketpunk" fighter* [Answer] They could work, but they wouldn't be super efficient at their job. They'd be easy to take out and they aren't bringing much to the table. Carrier based aircraft are generally at a disadvantage against ground based craft because they have engineering limits imposed by the length of the runway or weight issues - a water based carrier is going somewhere land based craft generally can't, which is why we accept the compromise. Having a carrier hovering over the land makes that compromise unnecessary. From a strategic perspective the best use you would get out of them would be extending the flight range of the onboard aircraft - they wouldn't function like a water based carrier in this scenario. You wouldn't carry logistics or repair stuff beyond some duct tape and glue - you carry fully loaded planes up to your capacity, move forward at high altitude at night, launch your planes right before dawn and then hightail it as quickly as possible to the rear. Then land, so you can reload and do it again. This would give you the ability to hit targets further into enemy territory, and coupled with strategic surprise could be a pretty good first strike weapon. If you are really an evil empire and don't care about your minions, you could use your flying carrier to do something that a ground base simply can't do. Instead of heavy aircraft, load your carriers up with <https://en.wikipedia.org/wiki/Rotor_kite> which comparatively weigh basically nothing, require way less maintenance and are easy to 'fly'. You could have a couple of small bombs attached to each and you just drop a bunch of them over the front lines. If they make it back, fine. If not? Who cares. They are ridiculously cheap compared to airplanes - we can make more! In either scenario you need ground based fighters flying defense. [Answer] [Crimson Skies](https://en.wikipedia.org/wiki/Crimson_Skies "Crimson Skies") is a PC game that covers this very topic. The world is shattered and transport infrastructure is degraded to the point that air transport is the only viable option for the most part. The game revolves around the airship *Pandora* and is set in the 1930's. Aircraft are launched by dropping from underneath the airship and are recovered by a hook connected to a crane. The crane lifts the aircraft back into the hanger. Besides its integral squadron of aircraft, each airship tends to be armed with AAA turrets and aerial torpedoes. [Here is a trailer.](https://www.youtube.com/watch?v=dtSMoGF7aS8 "Trailer") [![Devastator](https://i.stack.imgur.com/QdA4x.jpg)](https://i.stack.imgur.com/QdA4x.jpg) [Answer] No. You'd be much better off focusing your efforts on perfecting **mid-air refueling**. You have the tankers *drag* the fighter aircraft to the edge of the combat zone. Dragging means the tankers *escort* the aircraft they are supporting the whole way, topping them up enroute as needed. Before they reach the point where enemy fighters could threaten the tankers, every fighter tops off tanks, and the tankers hang back and loiter. The fighters spend all their ammo, and return to the tankers, who drag them back to a friendly landing site. It's also possible the "escorting-to" tankers could drag the fighters in, turn around and go home, and a fresh squadron of tankers appear to drag the fighters back home. This would be more effective, and much more practical, than a dirigible. The number of fighters it could support would be limited *only* by available aircraft and pilots. ]
[Question] [ Viral zombies, that is zombies that are alive, are much more terrifying than their undead equivalents. While they lack the required headshot of their undead brethren, they are faster and often smarter. One disadvantage they do have is that logistically speaking, they will die out before they can become a full blown apocalypse (Like in *28 Days Later*). But can this be avoided? While it is never explained how, the infected in *The Last of Us* are able to survive years without food as well as exposure and below zero temperatures; a survival feature nearly exclusive to undead zombies. How can I justify living zombies that can survive the elements? [Answer] Maybe the virus allows the zombies to go dormant when there is no animal life nearby. It lowers the infected host's metabolism to something akin to hibernation or along similar lines to insects that can survive winter freezes. Then there's the possibility that doing so allows it to stay alive for extended periods, only raising its metabolism in response to nearby life (sound, smell, whatever). At that point, the virus revives the host. This also explains why the host is so slow when it first senses life, but then speeds up as stiff, dormant tissues come to life. This isn't going to give you immortal zombies. But you could stretch this to allow at least a few years. Longer, if wildlife rebounds after human civilization collapses.Since that would provide lower life forms the zombie can catch and eat for a bit of sustenance from time to time. [Answer] There seems to be a couple issues you've asked about: How can the virus spread into a full blown apocalypse, and how can virus zombies survive for long durations in the elements. # Spread Spread is the easy problem to solve: give the zombie-ness as the last symptom of the disease....one that doesn't occur until after the person has been infectious for some time (days? weeks? months? you decide. Longer the period the more dangerous strangers are in your world). The virus itself is interested, biologically, in spreading as much as possible. It could have evolved as a "slow burner" that starts off as a relatively mundane infection, perhaps causing higher blood pressure or some other small symptoms. As the disease progresses, it changes the bloodchemistry, causing heightened "fight or flight" responses to other living things. Simultaneously, absent of these stimuli, the bloodchemistry slows the metabolism. Add in some brain lesions in certain areas, and the person will see every living thing as "food" even if they retain some of their critical thinking skills (much like animals that are infected with parasites retain their abilities to move, but lose inhibitions that keep them from being eaten). Eventually this goes full blown zombie, viciously attacking any "meat" that comes near. The virus spreads from any fluids and tissue of the creature, and could even be airborne if you wanted. The complications of a water or airborne virus would be difficult to handle indeed. # Survival If the body is kept more or less intact, and can be fed (by the zombie viciously attacking any "meat" that comes near), then it should be able to survive for some time. This can be enhanced by lowering the metabolism of the organism for some time, until spiking it with adrenaline in response to stimuli (there are instances of snakes spending many years sealed in wine bottles that wake up and attack the opener of the bottle. Obviously, we aren't reptiles, but bears hiberate, spending months not eating). In terms of infection, the virus itself could provide safety there. Perhaps this virus enhances the immune system of the host to fight off infections, or attacks bacteria itself. You'd still get the "dirty zombie" look, you'd just not get the "rotten zombie" look. Add in biochemical changes that improve the body's response to trauma (enhanced swelling to reduce blood loss, or smarter clotting to seal wounds relatively quick, or both). Exposure might cause some issues, but there's no reason the biochemistry changes that affect the fight or flight response and metabolism can't also introduce some form of resistance to frostbite or heat stroke. You're already going to be lowering body temp by "hiberating" when stimuli are absent. [Answer] This is really very simple. There exists an animal vector in which the zombie virus is not terribly damaging. The term for interspecies diseases is zoonotic. The classic example is the Ebola virus, which apparently has such a host, although as far as I know nobody's found it. Avian flu is another example, and likewise, swine flu. And, of course, the phenomenon can be beneficial, as in the case of cowpox, which confers immunity to smallpox in humans. If, in addition, transfer from animal to human is unlikely (but not impossible), the virus can persist in the animal population, only occasionally crossing over to the human population and wreaking havoc. [Answer] How about a fungus-based zombie instead? The fungus spreads throughout the host, controlling brain-body function (see <https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis> for real-world examples of this -- the rest of the answer is pretty hand-wavy, I'm no mycologist). In the advanced stages, mushrooms blossom from the host (conveniently making them look proper rotted). Since most fungus feeds off of decay, you have a great source of resources; the fungus can feed off of rotting material in the hosts stomach (so no need to keep the digestive system running). The fungus drives the host to consume living creatures because they are a much more condensed source of energy. When such prey is not available, the host enters a dormant state. The fungus shuts down the body but keeps it alive by providing nutrients directly into the blood stream. To get those nutrients, it spreads from wherever it's host is rooted to the surrounding area (so a host beside a fallen tree might be preserved for quite awhile). You can imagine roots blossoming off of the host and leeching off of whatever else is around. Or maybe the fungus can cannibalize the host a little bit at a time, letting less critical pieces decompose in order to maintain the dormant state. When a threat or a new potential host is detected, the host body is reactivated, rising up from the muck to attack. Mycological colonies can be massive as well, so you could have lots of zombies all piling up against each other to preserve heat and share resources, maybe consuming the outer hosts first in order to better preserve more well-protected ones. This also has the advantage that the fungus can survive independent of the host and in very inhospitable conditions, remaining dormant underground for years at a time. So even if the original outbreak is contained, there's no guarantee that humanity has been saved... [Answer] The military were working on genetically engineered [super soldiers](https://en.wikipedia.org/wiki/Supersoldier). Using the latest advances in [gene therapy](https://en.wikipedia.org/wiki/Gene_therapy#Viruses) and insights gained from studying the DNA of animals with strong survival traits such as more efficient metabolisms, extreme temperature resistance, and ability to hibernate, a [viral vector](https://en.wikipedia.org/wiki/Viral_vector) was being developed that altered the host's DNA to provide augmentations. The lab were working to resolve some issues including a high level of contagiousness, and a side effect that caused subjects to enter a violent rabid-like state. The virus escaped before their work was completed. Because the zombies' DNA contains both the positive and negative genes from the experimental virus, they are able to survive longer than would be expected and in extreme conditions. ]
[Question] [ **Closed**. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Add details and clarify the problem by [editing this post](/posts/72661/edit). Closed 6 years ago. [Improve this question](/posts/72661/edit) What I'm asking is what comes next? We've got code, we have all this technology on earth- My world takes place in our timeframe and has identical tech. A supersized military computer from years ago is to an everyday computer as coding is to ? So far, I've only been able to think of those new brainwave scanning things- The ones that use your brainwaves to translate information. This can all be theoretical, and say that these people are able to create whatever the heck you're thinking of in the blink of an eye. They want a new TYPE of technology, a new form of technology, they want something new, not just stuck with what they have now. I understand it's a difficult question to put into words, so if any further clarification is needed I'd gladly oblige. [Answer] **Instead of Code, train or even teach.** - Jim Rush This is a tricky one because "code" is actually so fundamental that its hard to have anything else. "Code" is a communication mechanism. Any one directional logical communication you do is basically going to be code. To have anything beyond "code" I'd look at bidirectional communication. Instead of telling the computer what to do first, you tell it what to do and it asks for clarifications during the process of doing it. This is very different in nature from "code" because code has to be perfect before it is used. Any imperfections are blindly followed by the computer. If there were bidirectional communication, you could convey most of your intent first, and then work with the computer to clarify any unclear parts while it was working. Your idea of a neural link naturally settles into this pattern. While we *can* restructure our neurons to emit "code," it's much more natural to use them in a communication network to provide feedback while they are talking. [Answer] Coding, as we understand it today, is basically a series of unambiguous commands. Or, in other words, a series of information being processed by clear rules. Any programmer, especially the beginners, can tell how frustrating it can be that a computer always does exactly what it was told, no matter what the programmer's (or user's) intention was. This is based on the fact that the computer has no concept of intentions, and little to no concept of context. If you look at (live, not online) communication between two people you quickly realize that context plays a major part in most communication. You still have information, but with context (habit being one of many aspects of context) you get meaning. Granted, things are getting a bit fuzzy there, which sometimes results in misunderstandings, but the principle holds. So, if you want the next iteration of coding you could go with broad speech (and non-verbal) communication: you tell your computer what you want, the computer, much like a human counterpart, hears your words, sees your mimics and gesture, takes into account what was before, where you both are, and interprets your request, trying to determine your intention, rather than blindly following orders. [Answer] Look at neural nets. A trained network that gives results does not provide an algorithm that can be read back out! And saving it is not a list of procedural instructions to follow, but tables of weighting values. Look at the recent success with so-called “deep learning” and use that as your springboard. [Answer] Code is just human readable instructions that get compiled into machine code. The actual hardware instructions are simple: Fetch memory from address X, put in register 4 Add register 4 and 5 put result in register 6 It is by building huge chains of logic like this that computers do amazing things. There are many places to go from here. The most interesting is probably Artificial Super Intelligence bootstrapping itself. Currently there is a neural network that has been trained on code samples. It can assemble code to solve real problems. This is important because now the program can expand itself. There's nothing that says a program that writes programs wouldn't be able to use what it has written. Now programs written in code can write their own code. But why human readable code? The program could just as easily examine machine code. Now it is able to string machine code instructions together in a way that perfectly captures the peculiarities of a machine's specific hardware. Studies have shown that when evolving algorithms are involved they're able to take advantage of emergent traits that were never designed into them. Sometimes a minor flaw enables strange behavior. No circuit is perfectly built so there are always little peculiarities. Let's say this self programming machine could take advantage of internal interference as part of its operation. Now the machine is doing things it was never designed to do. Now allow the machine circuit assembly capability. The circuits won't have recognizable logic gates at all. They will be composed entirely of these weird behaviors, interference and cross talk, analog feedback loops. They'll operate far more like biology than electronics. Now the things we used to express in instructions and logic gates get done by tiny piles of silicon containing minuscule incomprehensible circuits. Now the ASI is going to want to incorporate the circuit manufacture capability everywhere. The circuitry can grow. Let's hope it doesn't choose to grow indefinitely. [Answer] The next step would be a fully networked turing complete natural language processing engine. Every single computer on the planet will link together into a neural network - and understand every single request. Every language, gesture and other body language (including micro-expressions) will be evaluated, local colloquialisms will be understood. In most cases, predictive analytics based on environmental scanning will allow the system to instinctively know what someone will want it to do before it's even asked - it will know the entire history of each user, and datamine the probable outcomes before anything is asked. Not learning to 'code', but just asking a computer to do something, and it having the skill and sense to infer exactly what was required based on the situation. No ambiguity or 'weird' loop behaviour, just pure understanding, based on the situation. It doesn't need to read brainwaves to understand - its 'deep learning' algorithms will be able to make perfect sense of any request. It has the entirety of human knowledge at its grasp. [Answer] Possibly symbols and images rather than code. Today, the vast majority of code is instructions on precisely how to behave and achieve outcomes/output. There are areas of computing (system provisioning via Desired State Configuration is a good example) where a change is underway to instead describe WHAT you want and allow other specialized systems to work out HOW to give you WHAT you described. So, a paradigm shift of sorts. I like your idea of a nueral link. Some sort or neural link to a computer system where the user is trained to communicate in Images of desired outcome and/or chains of Desired outcomes. [Answer] **Code is the next step after code.** The concept of "code" is fundamental. It is what we call the instructions that a computer uses to understand inputs and generate outputs. Asking *"What would the next step be after code?"* is basically akin to asking *"What would the next step be after math?"*. More math comes after math; increasingly complex math, sure, but it'll still be math. **What would the next step be after 'coding'?** This might line up more closely with what you're asking. Nowadays the concept of code is synonymous with Silicon Valley types drinking coffee and typing lines of instructions into their terminals, compiling, and running the programs. Asking if this will always be the way computer instructions are generated is a more interesting question, and in some ways we're seeing hints that this likely isn't going to stay the sole (or possibly even primary) method of code generation. Neural nets are becoming increasingly more common, as well as increasingly more sophisticated, and while these still generate 'code' the results are often strikingly different from a human-designed program. This computer-generated code typically defies the more linear logic of a human coder's instructions, but nonetheless it is still a set of instructions which take input and produce output. [Answer] So many thought-provoking answers. Let me add some more thoughts. I like the idea of having a bi-directional conversation with the computer. I tell it to do X. It does it. If it doesn't give me the output I expect, I modify the instructions or add more. The "code," which is nothing more than a sequence of instructions, evolves to the functionality I desire. I learned to program on an Apple //, using Applesoft (interpreted) Basic. I'd type in a statement on a line. It might gripe about that statement (if it was significantly flawed). I'd build a sequence of statements (a program). At any time, I could run the program and see how it behaved. The program evolved. It was a bi-directional conversation between myself and the machine. I could decide which parts of that conversation to keep in that context, which parts to throw away. Context is important; being able to save your work establishes, and allows you to regain, said context. Because the context needed for this problem is not, necessarily, the same context you need for another problem. Interpreters are notoriously slow. If you can get a particular piece of functionality "nailed down," it would be helpful if it could be compiled (for faster performance) and added to the environment, able to be called from interpreted statements. This is more of a polyglot approach, frequently found with Lisp systems. You can work with a REPL, building functionality, then export some of the statements from history into a file, edit it, compile it, make the compiled code part of the environment / context, go from there. I tend to think that interpreters / REPLs are a much more natural way for functionality to evolve, with compilers only getting involved once we want to optimize performance. Varying fractions of the context / "code" would get compiled. Eventually, maybe all of it. But maybe not. All program code, today, is typed in as text then parsed into an Abstract Syntax Tree. Skip the text, create the tree directly; make creating functionality more like dragging / dropping elements of functionality from a palette into a workspace, rather than typing. Put the nodes and trees into a 3D immersive environment and "code" in VR. Just how much more complexity could you view and comprehend if it was a 3-dimensional tree of nodes and connections, hanging in space? What is there to prevent you from creating (I hesitate to say "writing") "code" which would run across multiple processors? Nothing. Provide an input system which lets you see / manipulate collections of data and your "code" could scale. Any languages out there which do this already? Oh, let's see; there's APL / J, which has had interpreters available since the 1960s. And R, more recently. And SQL; I use the latter, pretty heavily, and it's not uncommon to see the machine chew through gigabytes of data, using a dozen or more cores. If I had more data and more cores, I could use those and do even more analysis on larger pools of data. SQL doesn't really do rigid sequences; this subquery calculates this, which gets used by that subquery which calculates that, with the results bubbling their way up to the final result. There's little in the "code" which imposes serial bottlenecks. Even if there IS a sequence involved, what's to stop you from running this rigid sequence across millions of data elements / subsets, in a map / reduce paradigm, auto-scaling it to, potentially, unlimited numbers of discrete cores? Money, time and hardware. Google did exactly that for their search engine. The sum of these thoughts is pretty far from the modern paradigm of typing code into a text file, feeding it to a compiler, linking it and testing, then going back to typing for the fix or the next stage in the development. Since tablets and VR really aren't good environments for typing, I expect to see some of these developments sooner, rather than later. [Answer] [Parallel processing computation](https://en.wikipedia.org/wiki/Parallel_computing) is the answer. Yes it is that simple. Admittedly the complexity of programming parallel processing computers will be a hurdle. Computers today are basically Von Neumann serial processing engines. A single parallel computer could do all the computational tasks of an entire city. There would be no need for all those individual serial processing computers. However, it will take an enormous amount of investment to get here. First, to develop the technology, and secondly, to implement on a wide scale. ]
[Question] [ I'm looking at the idea of a large feline as a rideable mount, and I'm running into a question about the rider's posture when riding. Would it be best to have the rider mounted Prone, like on a modern racing bike, or more upright, like on a more classical horse. Or even a bit more reclined? This is a designed feline mount (ancient wizards), so things like spine flex and all the other problems with feline mounts (like described [here](https://worldbuilding.stackexchange.com/questions/234842/adaptations-necessary-for-a-big-feline-to-be-rideable/234849#234849) and [here](https://scriptveterinarian.tumblr.com/post/154735569569/so-beasts-of-burden-of-the-large-feline-variety)) are not a problem, or at least not for this discussion. The creature's designed intent was a fast moving, short range mount. Think a day or two's travel at most to get around the flank of an army, to get the spec-ops team into their area of battle, or for a quick getaway. This is not long hauls over great distances... the mount wouldn't have the stamina for that day for more than a couple days. I **like** the concept of the Prone position, and it has history to it (See the *Gandalara Cycle* for example). I'm just not sure about position as a longer term ride either for the mount or the rider, and how the seat posture affects things like: * comfort * visibility (fore and aft) * endurance * the mount's mobility. I'd also appreciate any feedback from motorcyclists with real word experience on the two styles of seats and middle range Notes: 1. This is not for riding in battle, they would be more likely to dismount for that because 1) cat fighting, and 2) other reasons not pertinent to this discussion. 2. I'm loosely basing the mount's build on an oversized Tiger, or a *smilodon populator* without the teeth. I might shorten the torso, depending on the rider's posture. 3. This is not a land of giants. Super big cats also break normal sized tree limbs, so less climbing. Yes, we do have to take the vertical into account some, and while I would would like ideas on how that would affect the posture it's not a dominant thought. 4. I'm also not caring as much about how the "saddle" is attached (as described [here](https://worldbuilding.stackexchange.com/questions/95427/how-to-make-a-saddle-for-a-feline-mount)) but how the rider would be sitting on it. (If needed I can do a magic glue saddle attachment points.) 5. Yes, this word does have magic, but it has rules, and I'd rather not have to stretch the rules here. Edit note: Corrected from **Supine** (on the back) to **Prone** (on the belly) which was my intent. Thanks to Monty Wild. [Answer] Motorcyclist here. Well, Currently between Bikes Motorcyclist. I used to commute daily on a 120km round trip (60 km there, 60 back) - my Bike? A Suzuki Hayabusa. I put 100,000 Km on that thing and a good percentage of that was in heavy traffic. Initially my bike had stock handlebars (more of a Sports bike feel) but I put on a Bar Riser kit (this info will become suuuuuper relevant shortly). I also did this when I was rather unfit (peak weight 130 Kg) and not very physically active, although whilst still riding daily, I did slim down to 103. As an aside - I'm currently 93 - trying to get to 85. It's a long journey. On a Bike, on the Open road, travelling at Motorway speeds (100 Kph/60 MPH or there abouts) a Sports Bike position is actually quite comfortable - especially if you don't have a lot of upper body or core strength - the Wind stabilizes you and takes the pressure off your wrists. With the stock bars on a long-distance trip, I could ride for hours without getting tired. However... You'll note I said most of my riding was done in heavy traffic, even though I was filtering through the traffic (Legal in NZ due to vagueness of NZ law) I was still only doing about 50-60 Kph, and making very frequent usage of my Brakes. A forward leaning Sports bike position at those speeds and is not comfortable, it's hell on your wrists. Now - you might see very fit guys or guys in their 20s saying how they can daily a Gixxer or similar Sports bike and it's not a problem on their wrists - I would call into question how many of them *actually* daily their bike. That position is good for leaning for corners, good for hanging on whilst accelerating hard (God I miss my 'Busa....) - but for slow speed, with lots of breaking *or just things that cause your weight to go forward* - it's not comfy. The Bar riser kit I got was something like this: [Here](https://spieglerusa.com/suzuki%20-hayabusa-handlebar-conversion-kit-1.html) This shifted the riding position to a Sport tourer type position [![General Idea here](https://i.stack.imgur.com/84bAJ.png)](https://i.stack.imgur.com/84bAJ.png) This took the weight significantly off of my Wrists and lower back - resulting in a nice comfy ride. This, however, is for a Motorbike riding on flat and level roads - the movement of a Cat, no matter how graceful will be more jarring - much like a Horse - and for a more aggressive position, this jarring would be much worse than braking in heavy traffic because some... 'driver' is unaware of these magical devices on their car called 'Wing Mirrors'... So a leant over position would be a no-go. In addition, a Cat isn't going to be hitting the speeds necessary for the wind resistance to make a leant over position comfortable. You could perhaps make an argument that if they were in Combat, a leant over position would be advantageous for helping the Car corner by leaning - but since you've said no direct combat - I'm ignoring that. **TL;DR** you would want an almost vertical upright position, much like a Horse rider, leaning forward or back as and when needed - but the majority would be sat upright, as to do anything else would cause absolute pain in your wrists and lower back. [Answer] The issues of riding any mount or even a vehicle in a supine position (effectively lying on the back) are similar, whether it is a cat, a horse or something else. I also believe that the OP has mistakenly substituted *supine* (lying on one's back) for *prone* (lying on one's front). 1. Human heads are mounted on the neck and normally face forwards while the torso is upright. Altering the posture to a supine position while *still* needing to look forward necessitates bending the neck forwards to a degree proportional to the leaning-backness of the riding posture... or bending the neck backwards if the OP meant *prone*. In either case, this bending of the neck is a departure from human neutral posture, and the greater its degree, the more rapidly it will cause discomfort. Secondly, riding astride an animal or vehicle in a supine posture limits the ability of the legs to grip the mount's body. Human legs flex forward relatively easily, up to 110°, but do not extend backwards very far, perhaps 40-45°. A supine position may work for a vehicle in which a seat that is leaning back may be used, but it does not work well for an astride seat where the legs must point downwards. A prone position works much better. 2. In a fully supine position, the rider must see past his own body and the head of the mount, while when fully prone, the mount's head will be in the way. In-between, there is likely to be stress on the rider's body from the necessity to support themselves in that position... especially when partially supine. 3. A non-upright riding position is going to reduce the rider's endurance. It takes more muscular effort to maintain a leaning position, whether backwards or forwards. Human muscles are not like electric screw-jacks that use power only when changing position, they are working constantly, and consuming more energy when in an unbalanced position. 4. The rider's posture won't affect the mount's endurance or straight-line speed much, since it won't be going fast enough for aerodynamic drag to become much of an issue, but it will affect its maneuverability. When sitting upright, the rider's body and center of gravity is located more or less over the mount's center of gravity, and does not extend forward or rearwards much. As a result, turning would be easier and faster than if the rider was entirely prone or supine, with their mass spread out along the mount's body, requiring more force to rotate the mass that is spread-out across the plane of rotation. So, to summarise, the upright posture adopted by horse riders has been adopted for good reason. A leanoing-forward prone posture may be adopted in order to wring just a little more speed from a galloping mount by marginally reducing drag. As for endurance, for a big cat, a couple of *minutes* of running is a very long time, and a couple of days at anything much above a quick walk would be unthinkable. Cats are not endurance hunters like wolves or humans, they are sprinters, and if they don't catch their prey in a few hundred metres, they give up. [Answer] I try my best not to be ageist, but the essence of the question leads me to believe we are from different generations. Anyone who had their infancy between the late 1970's to early 90's should immediately and outright say upright riding. And that's because of this guy: [![He-Man riding on the aptly named Battle-Cat](https://i.stack.imgur.com/tQUaB.png)](https://i.stack.imgur.com/tQUaB.png) [The Rule of Cool demands it.](https://tvtropes.org/pmwiki/pmwiki.php/Main/RuleOfCool) Now, on a more serious tone, let's go over the separate points in the question: ### Comfort TheDemonLord already gave [the perfect answer on this](https://worldbuilding.stackexchange.com/a/251459/21222). ### Visibility The higher your head is, the farther you can see. Also try it yourself. Sit on a chair, put your hands on a table and turn your head around to look back. Now get on a bed, hump a pillow from above and try to look back. Which one was easier? ### Endurance The human head was made for connecting to the neck from above. You go supine, and you have to pull your head up, like superman when he flies. You spend a considerable amount of time doing that, and you will be making a chiropractor richer in the near future. ### Mount Mobility You very probably won't be going so fast as to act as an airbrake atop your cat, so air resistance shouldn't be an issue. And as long as you carry a loaf of bread covered in butter with you, the cat should be gyro-stabilized in even the harshest of conditions. [Answer] I have, over the years, ridden both horses and motorcycles and I would suggest that you stick to horses all the way for this one. Modern sportsbikes are designed for a very specific environment, smooth tarmac, and hence give you limited freedom of movement, left and right. In practice it's an almost unique posture for control of any mount, the closest being racing bicycles. The advantage of the classic (European) horse riding position is the ability to move your weight around fairly freely. Your cats are going to be scrambling up hills, jumping rivers, crouching behind hedgerows. The freedom to stand in the stirrups, to shift your weight forwards and back aiding climbing and descent, to rise out of the saddle and take the impact out of jumps. All of this is going to be essential to your riders. All of that is in addition to the comfort issues @TheDemonLord mentions, remembering that you're unlikely to have hardpoints resembling motorcycle handlebars that you can actually lean on on an animal mount, so you need even more strength in your core to maintain that posture. Currently an XSR700 if you're wondering, chosen over competitors primarily for its more upright riding position and longer more relaxed leg position. [Answer] This is a frame challenge. --- [![enter image description here](https://i.stack.imgur.com/aLcNg.jpg)](https://i.stack.imgur.com/aLcNg.jpg) ## Give the cats a sled or cart to pull. We've used sleds in the past to allow us to use animals for transport when such animals wouldn't be able to be properly ridden - dogs being the prime example for that. With a sled, the anatomy of the cat becomes less relevant, and you solve a bunch of problems at once. With a quick-release system, you can even send your "Pack of Cats" towards your enemies quite easily, unleashing a storm of claw, fur and hisses. And, I mean, you can't beat [this level of cool](https://www.youtube.com/watch?v=lceSo10_d9Q), when it comes to cat-travelling.. [Answer] Best for whom? Professional jockeys get the best performance out of their mounts while riding like this : [![jockey riding a racehorse](https://i.stack.imgur.com/rKAPN.png)](https://i.stack.imgur.com/rKAPN.png) (Image from : <https://fitfreaks2.wordpress.com/2014/06/05/athlete-of-the-week-a-jockeys-hard-life/>) This crouched position minimizes the strain on the horse, but it's incredibly hard on the jockeys, who have to be very fit and strong with great balance and reflexes. <https://fitfreaks2.wordpress.com/2014/06/05/athlete-of-the-week-a-jockeys-hard-life/> <https://www.twinspires.com/edge/racing/the-science-of-horse-racing-why-do-jockeys-ride-like-that/> This position would enhance the speed and mobility of the feline mount, while increasing the skills needed and danger faced by the rider. I personally think it'd be pretty hard to stay on a pouncing twisting feline in that position without some sort of telepathy. ]
[Question] [ So I’ve got a nice point-A-to-point-B teleporter machine, and for some extra flavor I’d like to have the experience of using it include a healthy dose of gravitational/physical warping to push, pull, squash, stretch, and generally jostle around the user; stretching some parts a bit further than usual or in new directions, distorting their body a bit, maybe some particles from the “outer” layers (skin, hair, etc) moving away from the body and generally acting somewhat less like a solid…the usual “things get a little weird at light speed” treatment. Don’t worry—all particles, physical forces, and body parts are carefully stabilized before the end of the process, so that all is back in place before they step outside again. But I’d also like to have my characters acknowledge that experience, and be both alive and in well enough condition to do so (not to mention, to have the teleporter to be practical at all). How is it possible so much spatial warping, not just of the teleporter interior but even of the user’s body itself, can occur without killing, hurting, or otherwise being very painful for them? (Some soreness afterwards seems to be a given, though.) Now it’s worth mentioning that this teleporter does already use a protective force field-like “envelope” or “layer” to shield the user from too much damage by the effects of pushing them through a wormhole or traveling at extremely high speeds, and that could help minimize the effects of that warping thanks to its function as a “protective bubble” of sorts. This could maybe have some sort of effect or hand in allowing that pain/death-free body-warping to happen, or function as the tool that whatever method allows for this effect is performed through. (But remember that it’s not just a matter of using that force field to stop the warping—the question is about it being a given for the user in a way that won’t hurt or kill, not about how to prevent it). [Answer] **You can't do what you're suggesting to the degree you're hoping for in the way you want** This is a [frame challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609). In many ways the human body is remarkably resilient. Somebody smacks you on the arm with a stick. Flesh, muscle, all kinds of things move around leading to bruising, damage, and pain. Maybe someone jovially taps you in the tummy. You lose your breath, but no real harm done, and everybody starts laughing a bit later. You get on a roller coaster or some other ride and get spun around, not just playing with your inner ear's balance, but actually jostling you something awful! You stagger off the ride, proudly proclaiming that you want to go again. It seems like these are the kinds of experiences you're looking for. The problem is that *during transport* it's irrelevant what happens. That's all energy transfer. There's no feeling or comprehension. It's the period of the event that's explained using technobabble to justify what happens next. During *reconstruction* of the body whatever happened during the transmission phase (and, much more likely, what's happening during the reconstruction phase. We'll get to that in a moment) is made physically manifest. *But you can't change too much of the body.* The "jostling" that happens during a roller-coaster ride or a tilt-a-whirl is not what's happening here. This is more like stirring pigment into paint. Once you've stirred pigment into paint you can't get the original color back. It's dead. **And that's your basic problem** You want people to *feel weird* about an experience but the process you appear to be relying on is a physical process that will result in dead people. You don't have a period of time where flesh is compressed or the body is moved around. All you have is the *aftereffect* of something that's (at best) *interpreted* that way. Otherwise, you have dead people. The damage caused by that stick to your arm is happening in a fraction of a second — but imagine the consequences if all of the action *occurred instantly, with no delay at all* (such as during reconstruction). That would cause much more damage. It might shatter the arm, rupture blood vessels and tear flesh that would otherwise have been only bruised. I therefore suggest that this has nothing to do with the transport phase of your teleporter's action. Frankly, whomever engineered the teleporter did a lousy job if they didn't compensate for effects during transport. Have you ever driven in a car that had no shock absorbers or springs? You're going 3-5 miles an hour and it's a back-breaking experience. Now let's take away the cushion (and springs) on the seat and the rubber (and air) of the tires. You can see my point. Engineers *long after the invention of such a terrible carriage* would never let a potentially harmful condition arise. And if they were tempted to due to corporate greed or something like that, no decent bureaucracy would ever allow it lest the users of said transporter start voting for someone who will fix the problem. **Reconstruction is your enemy** Which means we're talking about something during the *reconstruction phase* of the experience that's leaving people *feeling like* they've been turned a bit inside out. In other words, there's no actual danger in the teleportation experience. It's perfectly safe by design. But there's no way to stop you from feeling weird about it any more than a safe boat trip on a calm, sunny day can still leave you utterly sea sick. *Said better: all of the conditions you mention in your post like "spatial warping" is nothing more than the technobabble that rationalizes the idea of "and that's all compensated for during reconstruction" which is what results in the feeling of sea sickness.* An example: I remember reading a short story once about a space traveler having to make a choice to use an emergency teleporter due to system failure. He was sure to die if he didn't use it. What was the crux of the story? In that world, teleporters didn't move the unique person from one place to another. They were more "realistic" in that they were duplicators. Once you pushed the proverbial button, what appeared on the planet was a duplicate of yourself. One that was perfectly safe. *But "you," the original "you," were still on the ship... dying in a very horrible way.* If I recall, the story investigated themes like what it was like to use a life-saving device that still made you feel complicit in a horrific death. What it meant to realize that you were not really you — that the flesh had never been touched by a loving spouse or had even touched the fabric of clothing before, but still had the memories of those things. If I recall correctly, the story even touched on the philosophical question of, "am I really me?" **So I recommend you change your focus a bit** If we ask the question, "what could make me feel the equivalent of *sea sickness* in an energy teleporter world?" you have everything from "am I really me?" types of psychoses to the "vibration" of the atoms in your body not being quite the original, which would still let you live just fine, but could rationalize feeling really weird. But to give you a better or more focused idea of what could specifically cause these feelings in your world would require a much more specific explanation of how the teleporter *procedurally* operates. From the moment someone decides to use the machine to the moment they walk away after transport, what is happening to them step-by-step? *E.G., my machine solves the duplication problem by destroying the original body. It's actually part of the process. It's impossible to "interpret" or "read" the structure of the body and its energy without dismantling it in the process. This means that some part of the brain is "feeling" this experience of "dying" the instant before dematerialization is complete and that feeling is retained... ah-hah!* But as you think about that, remember that the result of the teleport cannot have in any significant or measurable way any actual change to the physical body — otherwise you have everything from a vegetable on the transporter pad (synaptic pattern failed to resolve, nobody's home anymore) to a [pile of mush](https://youtu.be/IipR1LUYRZI). [Answer] Because it isn't actually happening, it's just how the body percieves the experience to be. The nerves and other receptors are hit with information they cannot decipher properly, and think they're being turned inside out while being twisted into a couple of imaginary dimensions. This isn't an experience we have evolved to understand. The same thing happens with people who sniff glue and other altering substances. Their minds and bodies think they're doing impossible things, then they snap out of it and their bodies are normal. [Answer] "Gravitational warping" doesn't warp *things*, it curves *space*. You make it survivable by ensuring that the space where the user is stays mostly flat, with the vast majority of the warping happening in the space around him. This is the "warp bubble" idea that you've probably heard many times before. [Answer] **Discontinuous acceleration when moving between gravity domains** Human body is sensitive to sudden changes of rate of acceleration, which is called [jerk](https://en.wikipedia.org/wiki/Jerk_(physics)). If the teleporter start and end point have different local gravitations, the change will be easily perceptible - the faster the change, the higher the jerk. To make the trip survivable, it probably has to be very quick - otherwise body processes such as blood flow and neural signals would be disturbed. This puts a limit to how comfortable the ride can be made. For elevators, ISO 18738 standard specifies 6 m/s³ jerk as intolerable. For example a teleporter trip from orbit down to Earth would involve a gravity change of 10 m/s². To keep it under the "intolerable" level, a 1.6 second transition period would be needed. But that is probably too long to keep a body in a transition state. With suitable physical supports, much higher jerks can be survivable, such as in car accidents. As a summary: teleport between two spaceships? Fine and comfortable. Beam down to planet? It's gonna feel like a car crash, except without actually hitting anything. [Answer] # Take it for granted "How does it not kill someone" is **only** a question that would be asked when the thing explained, and the explanation is lacking. I'll jump on the don't-try-to-explain-it wagon, because no matter what technobable you come up with, you will *absolutely* be wrong. Astrophysicists with ten doctorates in theoretical spacetime phenomena would be wrong. Everyone in-universe except those uppity non-relativistic gravitational spacetime majors at University just takes it for granted that the user feels like they had a brief acid trip, but come out alive and well on the other end. The same way you can have a Zoom call with Grandma and sometimes the image is pixelated or the audio is choppy, you don't need a network engineer to explain to her why, and she will still be happy to see her favorite grandchild. [Answer] # For the same reason jumping to warp speed doesn't immediately kill everyone onboard the Enterprise Gravitational effects occur because spacetime itself becomes warped. If the warping is homogenous across an area, nothing happens to objects within that area since, from those object's perspective, nothing has really changed. It's only when gravitational warping becomes heterogenous across an area that weird stuff happens inside it. If you have space on the left half of your body that is pulling you in a different direction or at a different acceleration than that of your right half, you're going to feel the difference. Once that difference is great enough, the results become a bit graphic. This is what happens near a black hole as well. As an object falls toward the center, gravity is acting on the side closest to the center stronger than the side furthest. It's this difference in forces that are what ultimately tear the object apart. The behavior of wormholes is somewhat ill-defined in science considering how they've only ever been theorized, but in science fiction they are commonly portrayed as similar to (if not synonymous with) black holes. As you approach the wormhole, spacetime will contract and elongate differently depending on how close or far you are to the threshold. In all likelihood, this would have similar results to the object entering a black hole, with the only difference being that instead of the particles collecting at a singularity, they are jettisoned into space in a shotgun-spread on the far side of the wormhole. ## What does this all have to do with the Enterprise? Warp drives in Star Trek operate on a different technological goal, but they would deal with very similar gravitational effects. When the Enterprise utilizes its warp drive, what it's actually doing is creating a pocket of stabilized spacetime around the ship and then bending spacetime itself around it. Without that pocket, the warp drive wouldn't just distort spacetime around the ship, it would distort it *within* the ship as well, which would almost certainly obliterate the ship and instantly kill everyone aboard. This is how the Star Trek universe gets around the speed-of-light barrier. By introducing a technology that warps spacetime, the ship itself is never actually moving faster than light. Instead, it basically "warps" spacetime to greatly decrease the distance to the destination, making travel to there at sub-light speeds actually manageable. Your wormhole-based teleporter would have to accomplish something similar. By surrounding the user in a bubble of stabilized spacetime, everything within that area would be protected by the wormhole's gravitational effects. You can then proceed to punch a hole in spacetime, shoving that bubble through so that it ends up on the other end. To an outside observer, it might appear like the person shrank uniformly to an infinitesimal point in one spot and then grew from an infinitesimal point in another spot. The entire process would look strange, probably even quite comical, as though someone was using the Free Transform tool in Photoshop on a person to scale them smaller than a pixel before reversing the process. To the user themselves, the world would grow impossibly large, redshift into darkness, and then the new location would appear impossibly large around them before blueshifting back into the visible light spectrum while shrinking back to life size. Within the pocket itself, though? Nothing would happen. The user wouldn't experience any gravitational effects whatsoever. Just as long as the user keeps all arms and legs inside the bubble at all times, because anything that gets stuck outside is going to be staying outside. [Answer] # Quantum entanglement of their original state While the teleportation machine doesn't use directly quantum entanglement, the life preserving functions do. The start and end state of the person are entangled, and so the person is kept alive to the end. As such, while the person may be 'killed' by the transportation, it revives them fully by the end. In terms of how the deeper science of this works, it works very well, and experienced and skilled scientists in your novel can attest that this is the correct way to understand quantum mechanics. [Answer] Physical compression algorithm A person is compressed into the warp bubble by applying a multitude of physical forces. Think of it like an MRI, just with much more force. There are magnetic field generators, electric field generators, gravitational field generators, field suppressors, field deflectors, for some reason there are lasers, and all of that is superimposed and honestly almost nobody really understands why it works, but it does. However, the physical compression has losses, the forces don't quite amount to a perfect bubble, just to an approximation of the bubble. It's good enough, everything else would require so much more computational power that it just isn't economic. It's not a problem loosing an atom, molecule or a cell here and there or having it transferred to a place where it doesn't belong. You won't really notice the effect. Of course, the computational precision is higher at the brain so people don't worry too much. The rest is just what your brain makes of that experience. Bonus point: the VIP version works better. There's still debate whether this causes cancer or not. ]
[Question] [ I was thinking on the classic alien mass which spreads throught almost any surface, and in contact with live beings, it doesn't consumes them, but takes control of their minds in order to vary the means of spreading, which also can be the ability to control complex machinery. On my story, a contamined alien ship falls on a planet, and something on it would harm the infection enough to the main "host" be able to wake up from the mind control. I am trying to imagine a "natural" way to stop it, as if it was original from that planet itself, instead of something made by intelligent life beings. Also, consider it without any magic or similar. My first idea was simply a different type of crystals, which these could be harmful to the infection in some way, but I decided to see if there is better ways to deal with it, intead of having these crystals scattered around the surface of the planet. I am open to ideas, doesn't need to be scientifically accurate, only rational enough to work. Edit: Well, this is my first question, so I didn't knew how to make it properly, I ask apologizes(my first language isnt english, so bad grammar may happen) The disease was found in an abandoned asteroid, by a team trying to mine its resources. It is resistant to fire and can grow at fast speed in vacuum, however it still can grow in atmosphere. It is fully sentient, and works as a hive mind, until he gains control of the protagonist, using him to achive goals of further spread, as he is expert in controling spacecrafts. The disease also can grow tentacle-like parts in order to hold the "victim" and other objects of its interest. Some parts of it has "blob" like substances, these can explode and send parts of the infection further away, ir instantly contaminate the target. When I said "harm it enough to wake up the main host", I meant that it was in control of the protagonist, and the crash in the planet made able to him break free from the disease, because of the factor in the planet. [Answer] **A bacteria** or another microbe. Viruses and parasites are highly specialized so I don't recommend them. A bacteria or microscopic fungus, on the other hand, could feast on a compound of the "alien mass" and bar it from functioning properly. You can even have variations of the idea: some bacteria slow the mass down, some destroy it, some destroy it along with the host, some disable it but are intoxicated by the alien mass too (for example, the bacteria feast on substance A in the alien mass, and is slowly killed by substance B which is also in the mass) meaning the bacteria only last for some time or has a "range". You can make it a solution as you could grow it in labs, or you can decide it's hard to grow outside a host (the alien mass), so you can't manufacture it in a lab. You can decide that different bacteria has to be associated for it to work (Bacteria 1 feast on substance A and produce substance B, bacteria 2 feast on substance B and produce substance C, which kills the alien mass). The choice is yours! In short, it allows for a lot of flexibility in your story. [Answer] **A Hyper Parasite** I think you'll find your best answer in the parasites of earth - there's a large number that induce complex behaviours in their host species, such as Ophiocordyceps unilateralis, which takes control of ants, forcing them to infect their own nests, before crawling somewhere to die and release their spores This fungus also has a hyper-parasitic fungus (i.e, a fungus that infects the parasitic fungus) - this limits its growth, and can kill it. It'd be very reasonable for aliens to have a similar organism. What would be interesting is, that if all your aliens form a hive controlled by this parasite, an infection that clears the parasite would be terrifying to them - members would suddenly regain *shudders* free thought, and lose the sense of the collective hive. The parasite might, for them, even be closer to a symbiote, giving them the capacity for higher level, collective thought. This would also explain the ship crash - a ship full of aliens got infected by this, and turned on each other, destroying the controls and causing the ship full of the hyper parasite to crash land. [Answer] **It is cold.** Yes, I stole this right from The Thing. But it works fine here. On landing, the ship is damaged and climate control is damaged. It gets really cold. The parasite deals with cold less well than the host. The parasite is stunned into torpor. The host is also greatly slowed but is able to throw off the effect of the parasite to some degree. The host is far from in control of its full powers but is aware enough to understand what happened, and that it must stay very cold if it is to stay in control. [Answer] # Nuke it from orbit [It's the only way to be sure](https://tvtropes.org/pmwiki/pmwiki.php/Main/ItsTheOnlyWayToBeSure). You can use a [Tsar Bomba](https://en.wikipedia.org/wiki/Tsar_Bomba) at full power. At 100 megatons, the blast radius would likely be appropriate. You can simulate it by using [NUKEMAP](https://nuclearsecrecy.com/nukemap/). I put it besides Los Angeles to give you an area of the area you could cover: [![A map showing the size of a Tsar Bomba blast radius in comparison to Los Angeles](https://i.stack.imgur.com/mICY7.png)](https://i.stack.imgur.com/mICY7.png) Infections, alien or not, are a social issue. And in the words of the wise Vaarsuvius: > > As the size of an explosion increases, the number of social situations it is incapable of solving approaches zero. > > > [Answer] # **Invasive Species Model:** I am slightly vague on the details of your question (sorry) but I think you need to treat your alien infestation like an aggressive invasive species outside of it's native environment. Ecosystems where conditions are more favorable for an organism than it's own native environment cause uncontrolled exponential growth in a population. So you need to reestablish stability. I'm going to say your infestation (parasite) has a natural predator. That can be as simple as a fungus that coinfects the host, killing the parasite, to a sentient "parasite eater" that may either kill the host (decimating the population) or extract the parasite from the living host (preserving the host for re-infestation and a repeat of the infection cycle). The predator may be seeking out the parasite to feed on it, either as a secondary infection or as a separate independent being. It could compel the coinfected parasite/host to seek out and coinfect other hosts. If it's intelligent, it may have piloted a ship to the planet itself. A new pattern of infection/coinfection, or infection/predation will establish itself. This may mean the planet has a permanent low-grade infection, or the cycle could wipe out the parasite on the planet, and the overall life cycle relies on reinfection and spread of the parasite from planet to planet (depending on your desired outcome - permanent parasite/predator presence OR clearing of the planet until reinfection). If you have a fungus model, intelligent natives may maintain a supply of fungus to fight off future infestations. In an intelligent predator model, the predator may have its own agendas, possibly wanting to maintain a constant chronic infection to maintain a food supply (farming parasites, essentially). This is particularly nasty in the case where the predator kills the host, as the predator might be breeding, maintaining and deliberately infecting the population with parasites. If the predator leaves the host alive, I could even see a religious symbolism to the whole thing. The predators may be seen like gods or angels, setting people free, while the parasite is evil or the enslaver. Perhaps the culture even embraces the cycle, where the young are symbolically infected, then ritually freed by the predator. * **PS** Another thing that could arrive on a ship to devastate the parasites is knowledge. An alien from a previously infected planet tells them the secrets to fighting infection (they hate high pH, are poisoned by elevated iron levels, they can't transmit at low atmospheric pressure and are killed by the host being at too high like a hyperbaric chamber, etc.) [Answer] **Ways to control** I'll dumb down controlling to two ways. One is with hormones and such. (Gut) bacteria, virusses, fungi and the like can influence the body. Rabies makes people avoid water, mac donalds creates gut bacteria that prefer mac and thus a fraving for it (just a branded example), there's bacteria that can infect rats and humans to hang out more with cats and cordyceps fungi that take over mostly insect hosts and your nightmares after seeing youtube video's. The second one is direct brain control. This requires connection to the brain in some way. Both suffer from the same problem. An organism that isn't native to the host, meaning it's likely susceptible to different conditions. They can themselves be targeted by bacteria, fungi, virusses or even just a different environment. Getting warm, cold, humid or dry, a different diet or an infection can all lead to a disruption of the controlling organism. It can even be the controlled body to become sick, altering the way it needs to be controlled. For reference, getting hungry will already change the way neurons behave, making you see and do different things than when you were not hungry. What this means is that it can be any reason you like. A fungi able to penetrate the defences of the controlling organism? Just a bad reaction to getting rained on? Without further information on the organism, you have more of a dilemma of choosing the right kind compared to one at all. The rejection or losing of control can be sudden or gradual, as well as partial or full. If my boss loses control over me when he gets food poisoning from those bad shrimps or my other boss from his allergies, why not a controlling organism to the spicy food youre eating (a defensive mechanism of a plant). The host might just be better at handling that. ]
[Question] [ The first effective rotary gun was the Gatling Gun, invented in 1861 and it was a brutally effective weapon that had the advantage of high quality steel, rifling, and percussion caps. But for most of their history firearms didn’t have these features. For centuries firearms were but a metal tube and a touchhole. In my setting firearms are still throughly at this stage of development, but a mad lord has created a new design that’s meant to put the firepower of a whole squad of arbaquesiers into two man crews. The design consists of a wooden frame, cog and pinyon, and ten gun barrels attached to a wooden holder that is spun by cranking. The barrels can be pulled out by hand from the holder and are manually reloaded. The crew consists of a shooter and reloader. The shooter rotates the barrels via the crank, and fires them with a match and touch hole. The reloader then pulls out the barrel and begins to reload as the shooter rotates to the next barrel. These crews are used in both pitched battles and sieges, and their tactics vary accordingly. During sieges the crews fire through embrasures and on the field they are placed either in war wagons with cannon crews to form a mobile artillery unit, or within pike squares. So is it viable to have a rotating matchlock? Obviously it would not be an ideal weapon, but could it be put to use on a battlefield where guns are just starting to make a showing and all kinds of experimental weapons and techniques are being used? [Answer] This sounds more like a volley gun or a rather primitive revolver than a Gatling gun. The most important part of the Gatling mechanism is not that you have multiple barrels, but that they get automatically reloaded during firing. Volley guns were experimented with basically since the invention of the gun. But they always had the same problems. The reloads were too long and the weapons were too heavy. Some primitive guns were also designed as breach-loaders to speed up the reload and make preloading easier, but they had the problem that the breach was never really airtight. It is often said that the first useful volley gun was the French Mitrailleuse in the 1860s but in the end it was way too late and the Gatling gun was already invented. Revolvers, on the other hand, were officers' weapons for close-ranged combat. As other pistols they weren't meant to be reloaded in battle. Instead, when shot empty, their user would switch them for his sword. I think your design could be of mild effect against storming enemies during sieges. Wait till you can reliably hit your enemies and try to kill as many of them with your two available salvos, hoping that this will break their assault. In field battles I don't really see an advantage for them. [Answer] I don't think that it makes sense manpower or shot amount wise, mostly because reloading speed is limited and the point of diminishing returns is very rapidly reached. For example, take one man with a gun. Every shot, they need to manually reload. Now, if they have a friend who's preparing the reloads and takes the gun from the shooter the moment the shot is fired, then I think it would be reasonable that the team achieves a higher rate of fire than a single person. Here's the problem though: is one two man team faster at shooting than two one man teams? I don't think so because I doubt that delegating the act of reloading to a team member can cut over 50% off of the shot to shot cycle time. Even if this is the case, there is no way that adding a third member would increase the rate of fire with only a single gun. In summary, everything your rotary flintlock team can do can be done with much less complexity by just having two guns and swapping them between the reloader and the shooter. Furthermore, I'm not sure if this handing-off-the-gun-to-reload strategy really makes sense when you compare it to simply giving everyone a gun and having them reload by themselves. The only real situation I can imagine where handing a designated shooter pre-loaded single-shot guns is if the shooter is so skilled that having anyone else shoot would be the waste of a shot or there is only space for one person to shoot out of, like a narrow window or ambush hole. [Answer] ## With "historical" matchlocks, no. I think that you have a bit of a misconception. It appears to me that you are asking for a standard rifle-shell that's ignited via a matchlock. Such things were never used; the much better flintlocks and percussion caps were already around when the cartridge was invented. Now, in case that you really *were* asking about a Gatling gun with real-life matchlock technology, let me dispel you of that notion. **Regardless of numerous other problems (flash powder falling out, etc.) the reload on a historical matchlock is much too long.** It's pretty much impossible to create an autoloader for matchlocks with the technologies which were contemporary at the time. Without autoloading, your minigun would just be a weird-looking volley gun. Unfortunately, volley guns (e.g. the Mitrailleuse) aren't very good in field combat. They're just as bulky as a cannon, and take significantly longer to reload. While armies did use them historically, it was primarily as a specialized weapon to deal with cavalry charges. Being subject to the same excessive reloading times but with a much smaller number of barrels, your matchlock minigun would be quickly supplanted by more conventional volley guns. [Answer] While the weapon as described seems rather improbable, the [Puckle Gun](https://www.historic-uk.com/HistoryUK/HistoryofBritain/The-Puckle-or-Defense-Gun/) was a flintlock "revolver" gun patented in 1718. [![enter image description here](https://i.stack.imgur.com/RI4jI.jpg)](https://i.stack.imgur.com/RI4jI.jpg) *Puckle gun* There were several other early automatic weapons from that period as well. The [Chambers machine gun](https://firearmslife.com/chambers-flintlock-machine-gun-from-the-1700s/) from 1792 also used a flintlock mechanism, but a series of touch holes connected the barrels allowing for a volley to be fired at once. [![enter image description here](https://i.stack.imgur.com/2NjEB.jpg)](https://i.stack.imgur.com/2NjEB.jpg) *Chambers machine gun* Something like this would be workable as a matchlock weapon, and seems to be an extension of actual rapid fire weapons developed as far back as the late 1400's [![enter image description here](https://i.stack.imgur.com/zh7iT.jpg)](https://i.stack.imgur.com/zh7iT.jpg) *Rapid fire weapons as envisioned by Leonardo da Vinci* So for a matchlock fired weapon, Leonardo da Vinci seems to have found a solution to your problem in the real world. the gunner can fire one barrel, one at a time or sweep the match across the touch holes and fire all the barrels in a volley. Presumably, a battery of guns is emplaced so when one gun fires, the crew can swab the barrels and reload while another gun provides fire. [Answer] As long as there's only one person reloading, you can only sustain a rate of fire equal to the rate at which that person can complete reloads. If it takes him 60 seconds to reload a barrel, then you can still only sustain a fire rate of one shot every 60 seconds. While you *could* fire off ten shots in less than 60 seconds (assuming your matchlocks fire within 6 seconds of the match being applied), you would then have an empty gun and not be able to fire again until the loader catches up. Also, gun barrels tend to get rather hot when shots are fired. I wouldn't expect matchlock barrels to get nearly as hot as modern barrels for a variety of reasons, but grabbing the barrels out of the rotary gun would still be extremely uncomfortable and have a potential for burns unless you're wearing some kind of heat-resistant gloves... but such gloves would limit manual dexterity and impede the reloading process. So, overall, it seems that it would be much less complex, and probably a good deal safer, to just have a line of ten standard guns for the shooter to cycle through rather than combining them all into a single rotary monstrosity. The ten guns approach would also be more flexible, as it would allow the shooter's comrades to pick up guns themselves if the need arose. ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 4 years ago. [Improve this question](/posts/140041/edit) According to [this article](https://www.universetoday.com/15403/how-long-would-it-take-to-travel-to-the-nearest-star/), it would take tens of thousands of years to travel to the nearest star given today's technology. My question is, what could give the countries of today, or most of them at least, a strong enough reason to work together and build an extremely expensive spaceship and send a group of people (less than 500) to the nearest solar system? I don't want to worry about how this colony will survive for thousands of generations or what technologies would be implemented to do so. [Answer] **Because we're human & it's there** We started off in the middle of the desert, yet we kept looking at the horizon and wondering what's there so some of us risked their life & limbs (which at that point really was all they had) & walked there to find out. At some point we reached the ocean, and we got stuck for a while, that is until some clever cave man figured out that a tree that fall to the water in a recent storm floated, he stood at it and it still floated, suddenly the ocean, a mass body of water that no man can live in longer then he can swim (IE not long) and where every failure was deadly was possible, he didn't know what was behind the ocean (or even if there is something beyond the ocean) but that didn't stopped some of them to take the risk and get on fallen trees and try they luck. Time went by and the trees became large ships, crossing the ocean wasn't a big deal anymore so we started to look below it, sticking ourselves in what is essentially metal coffins just to go and look what the bottom of it looks like. But even that wasn't enough for us, birds can fly, we wondered what that feels like so we created planes to let us fly alongside them, it may have other uses now but at first it was just to fly for flying sake. Then we reached space, the final frontier, and like every frontier before it we are now there as well... not far away yet but our wanderlust knows no bounds, we have footsteps on the Moon & robots on Mars, we are actively working (and spending billions) all around the world (and working together, just look at the international space station) to colonize both in the not so distant future (sure most plans are still in the design stage but even the wright brothers started out that way). I promise you that once we get to a point we can have a human being live full time on another part of the solar system (which given your question states there's no need to worry about the tech needed I assume it exists in your world), you will still have people looking to other stars and saying "I want to go there", I know that because I am one of those people. **Reason? we don't need a reason, it's there and we're not and that's all the reason we need.** [Answer] # The survival of our species What happens if we suddenly have a nuclear war and all of us die? Or if the sun explodes? Our species would become extinct. That is why we need to colonize at least a second planet in another star. By that way, we will exponentially increase the survival chances of our species from mass extinction. # War. Survival from other lifeforms We aren't alone in the universe. It's very likely that there is something there, watching us or taking the galaxy. Just because we can't see any other lifeform it doesn't mean that the [Fermi Paradox](https://en.wikipedia.org/wiki/Fermi_paradox) is true. Maybe all of them are hiding. If there exist several lifeforms in the whole universe, it's obvious that at some point we will engage a war with them for the resources of the galaxy and possibly the whole universe. We should no longer rest, instead, we must start building massive spaceships to colonize as quick as possible the whole galaxy before others do that! Prepare the ships! [Answer] One of the things oft ignored in science fiction, is that once such a ship leaves on its journey, the cost of doing so becomes nil. That is, the economy on the ship is entirely self-contained. Talking about 'earth dollars', 'earth salary', and 'earth living costs' is meaningless. There ARE no salaries paid from earth. There ARE no support costs from earth. The inhabitants of the spaceship are as rich as they ever will be, in earth dollars. That is, absolutely penniless. But in terms of PPP, they would be as rich as the collective manufacturing capability of the spaceship. They could never own more than can be produced (or originally supplied) on the ship. The fact that they would never be PAID again is, of course, moot, because there is nothing for them to SPEND their income on. They can't send it back to earth. So one benefit, and a not insignificant one, is that these inhabitants, and their descendants, would be living 'free' in any earth-based sense. They, and their descendents, would never have to pay rent, a mortgage, food, car loans, or any other expense ever again. The potential to live in a perfect socialist commune type community, forever free from the yoke of money and of conceding it to others, is a very powerful motivator for many. In a sense. it would be the perfect 'convent', the perfect 'cluster'. And it pretty much guarantees that all of your descendants would live by the same philosophy. **TL:DR** It would be very appealing to a distinct ideological group who wished to enshrine their belief system in an environment that ensured it could not be altered, immune from any social or economic pressures from any other ideological factions on earth. Incidentally, there are a good selection of such ideological groupings on earth that are sufficiently wealthy enough to pull off such a feat. [Answer] I'd like to suggest a minor frame challenge. While it is unlikely to the point of impossibility that nations would sacrifice a major portion of their GDP to send a millennia long mission to another star, and a world-ending catastrophe is likely to be too fast and too destabilising to allow the construction of such a vessel, there are alternatives. ***1. The Eccentric Trillionaire*** In the relatively near future, space mining will likely become a booming industry, and the world will see the rise of trillionaire space executives. It is entirely feasible that such a person could decide that they'd like to invest their trillions in constructing an interstellar starship, and they'd certainly have the resources to do it. ***2. The Religious Exodus*** Another kind of organisation that could decide to depart the solar system without care for the cost nor ROI, is a religious order with enough funds to achieve it. Think something like Scientology, or the Church of Later Day Saints. They don't necessarily need a concrete reason, they just need their followers to believe that it is the right thing to do. [Answer] **In the near future, probably nothing. In medium term future, there is a number of possibilities.** Today, building a starship like that is simply impossible. But in the near future, when we'd be able to sort out all technical hurdles of sending humans to Mars, a giant interstellar spaceship will become a theoretical possibility. However, there would still be a number of issues that would make a success of such project highly unlikely. 1. Propulsion. Existing (or practically achievable) methods are too slow for interstellar trip, likely making it to last tens of thousand years. Even if everything else is done perfectly, we just can't expect our generational ship to function that long without a failure; 2. Energy. Solar panels won't be effective in interstellar space, and nuclear fission reactors are the only currently available option. This ship would have energy needs much much higher than a Voyager-type probe, which might not be achievable with current tech level; 3. Autonomy. 10,000+ years level of autonomy is impossible to get at our present tech level. 1,000 years *maybe* is realistic, but still something that we can only hope for; 4. Destination research. Right now we have a very limited ability to detect Earth-like planets in a target systems, and no way of telling if such a planet is a good candidate for colonization; 5. Money. As you have mentioned, this would be a huge undertaking, much bigger than the Apollo project, for example. So, I would think that even under the best conditions, building such ship in the next 50+ years is impossible. Of course we can try, but the project would have a very low chance of success. I can not think of any realistic calamity that would affect entire Solar system and give us enough notice to build this spaceship. However, looking further forward, all of the issues in the list above can be eliminated or somehow mitigated. New types of engines can be built, thermonuclear energy become reality, deep space experience would turn into confidence in spaceship's long term durability, our telescopes will find very Earthlike planets and new technologies like space elevator would make building spaceships in orbit very cheap. If the complexity of this project is reduced from the "Tower of Babel" to "Apollo" level, then we can find a number of possible reasons to complete it - from below-extinction level catastrophes to simple curiosity. [Answer] Any unavoidable world-ending event, such as a massive meteor hurtling towards earth with a 0% chance of survival. In such an event, the 500 people would be the highest tier professionals in the world in their respective fields, and most likely be people who also designed and built this massive ship, in case of repairs needed. In my head, it has to be something catastrophic to human life on Earth. Nothing less would cause all countries to put money towards any single thing. [Answer] If you watch the read the expanse series by James A Corey (or watch the TV series if you don't read great books!) then you come across another reason. The Church of Jesus Christ of latter-day Saints are building a generation ship to travel to another system. The freedom to take your religion and go to a fresh new world and live under your own rules free from the rest of the world would be extremely attractive to most religions, cults and sub-cultures. The only issue is who can afford it. I would suggest that organised religions are actually the most likely to be able to afford this (the catholic church owns a huge and incredibly wealthy land portfolio that is larger than the GDP of several countries). The more a minority is "oppressed" by the majority the higher their motivation to flee to somewhere they can live as they want. The only thing stopping all sorts of groups going off to try and set up their own ideal society is the economics. As noted above in other answers there are the curious and scientists also who would go just to see what was there and expand our knowledge of the universe. Leaving earth forever and having generations live and die en route is a huge price to pay but millions of people would choose to pay that price and commit their descendants to paying it also. Also don't forget how many people have pretty crappy poverty driven lives here on earth. A lifetime (relatively) safe constrained in a spaceship with food, books, tv and relative comfort is better than what a lot of people currently survive with on earth. Plenty of volunteers if you can solve the economic problems. [Answer] ***tl;dr*-** The only real reasons for trying to establish a distant colony today would follow from long-term interests. People who care about such long-term interests could be directly motivated, while others could be indirectly motivated. --- ### Direct motivations: Reasons for those who care about the long-term Reasons for humanity to spread out across the stars include: 1. **Survival of species and our legacy.** If something would destroy Earth or the solar system today, that'd pretty much be it for humanity. If there are human colonies elsewhere, then our descendants would live on. 2. **Scientific exploration.** There's a *ton* we don't know about the universe. Projects like establishing a trans-stellar civilization are likely to help chip away at our own ignorance. 3. **Greater technological output.** While it's unlikely that trading most material goods could be economical any time soon, our economy's increasingly interested in information anyway. Scientific/medical discoveries, technological advancement, and other high-value information could be generated and shared between planets. ### Indirect motivations: Reasons for those who don't care about the long-term The concerns are fundamentally about long-term interests like those above. Anyone who doesn't care about such long-term interests presumably wouldn't be interested in any action that won't see fruit any time soon following from their own motivations. However, even those who don't care about such long-term interests may still be indirectly motivated to pursue them. Examples: 1. [Elon Musk](https://en.wikipedia.org/wiki/Elon_Musk) claims to want to go to Mars to help ensure humanity's survival. This is a long-term interest that many don't share. However, as a billionaire who's established a company that can pay hefty salaries, Musk's own motivations can inspire others to pursue the long-term interests anyway, if only for a paycheck. 2. The United States won the [space race](https://en.wikipedia.org/wiki/Space_Race), getting to the Moon first. Which, if you don't actually care about getting to the Moon or any implications of it, doesn't actually matter to you – directly. However, there are people who do care, motivating the initial concern, while others got swept up in the goal through indirect mechanisms. 3. Stocks and other investments. If you have a large amount of money, e.g. in a retirement fund, you likely have stocks and other investments in which your actual money has been given to others for those others to pursue goals you may not know about, including some which you may agree with and others which you may not. Either way, it doesn't seem to matter; you have indirect reasons for funding those ventures, e.g. you want money for retirement later, so you've ended up giving your hard-earned money away to those projects despite not having direct motivation to have done so. 4. [Bitcoin](https://en.wikipedia.org/wiki/Bitcoin), as a specific case of the above example. A lot of people seem to buy Bitcoin out of the belief that others will want it and pay for it later, despite not caring for the use cases or/and ideals behind cryptocurrency themselves. This is, a lot of people have ended up paying their hard-earned money to enter the Bitcoin project despite a lack of concern for its goals. ### Physics analogy: Direct action causing indirect actions Here's a figure of a man pulling a woman on a sled: $\hspace{150px}$[![](https://i.stack.imgur.com/w6mXZ.gif)](https://i.stack.imgur.com/w6mXZ.gif) $\hspace{450px}$[$\llap{-\text{source}}$](https://www.chegg.com/homework-help/questions-and-answers/playing-daughter-snow-sits-sled-asks-slide-across-flat-horizontal-field-choice-pushing-beh-q15075907). Above, why does much of the sled and the woman's body move? Surely they don't care about the action of the man nor the rope directly. It's an indirect effect, where the motive force propagates through the system. Likewise, the core motivation for starting a project to travel to a distant solar system is based in long-term interests; there's no other *direct* reason that makes sense. However, all sorts of indirect motives follow from that, ranging from stuff like getting employed to pursue those tasks to national/etc. pride in it, to simply getting caught up in the enthusiasm of such a voyage as entertainment. Point being that the direct motivations are long-term, though indirect motivation can still pull the bulk of society even if the bulk of society has no direct concern for them. --- ### Conclusion: Long-term direct motivations are the ultimate reasons. Ultimately, the reasons to go to another star are the long-term stuff. Humanity's survival, scientific exploration, greater technological output, etc., are the only core reasons that survive in a vacuum. However, a lot of people may end up supporting a distant space colony if only for indirect reasons such as 1. to be part of a social movement that's excited about it; 2. to be paid for working on it; 3. to show off as a mode of self-advertising; 4. to have fun doing something that others care about; 5. to have a stake that others might pay them for later as an investment. If you're writing a story about something like a space colony project being launched in the near-future, it's likely that most people in that world will buy into it for an indirect reason rather than actually being concerned about the core motivations themselves. [Answer] **The Sun goes supernova.** Similar to [this answer](https://worldbuilding.stackexchange.com/a/140074), except more violent. Sure, in reality, the Sun doesn't have enough mass to actually go supernova, but perhaps as the author, you could engineer some unexpected anomaly in our star that would be enough to give it a spectacular premature death. Knowledge of an upcoming event that would completely sterilize the entire solar system should be enough motivation for us humans to get pour all of our resources into getting the frick out of the system before that happens, I should think. A related short story: ["Rescue Party"](http://www.baen.com/Chapters/0743498747/0743498747___1.htm), by Arthur C. Clarke. [Answer] ## Good night Sun In the future, the sun is not going to keep being the life sustaining ball of light as we know it to be. 1. First, it will increase temperature, becoming brighter and brighter. This will make Earth life as we currently know it impossible. 2. Next, it will grow into a red giant, consuming the Earth. Earth life in any form is know impossible. That also means all the resources on the Earth (including all known organic materials) will be lost. 3. Finally, the sun becomes and white and then a black dwarf. Now, life in the solar system has a time limit, since there is no longer a source of energy. So, at some point along this path we will have to flea the solar system or die. Humans do not like to die usually, so we will probably choose the former. Luckily, it should be feasible by then. Now, as for whether we will choose the heat death or something else? [THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER.](https://www.multivax.com/last_question.html) ]
[Question] [ Trying to create a future earth which has been thoroughly abused by the excesses of modern capitalism. Extreme weather, rising sea levels, massive droughts, that sort of stuff. My question is: could fracking, on a large enough scale over a long enough period of time, plausibly affect the movement of the tectonic plates? Would it be possible for them to noticeably shift in a span of 100 to 200 years? [Answer] Tectonic plate shift takes place at the level of the [astenosphere, which is at least 80 km down](https://www.journals.uchicago.edu/doi/pdfplus/10.1086/622181). Hydraulic fracturing takes place at depths [one order of magnitude shallower](https://en.wikipedia.org/wiki/Hydraulic_fracturing), and [the deepest bore ever drilled](https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole) was no more than 13 km in depth. Therefore, fracking cannot reach the astenosphere, and given the viscoelastic properties of the Gutenberg discontinuity, neither could any hypothethical "fracture creep". So, no, you can't influence continental drift using hydraulic fracturing. Actually, even if the astenosphere could be reached with frackers (there would be no reason to do so, as kerogenic strata cannot possibly be found beyond Archaean depth), the whole operation might probably not work anyway, because evidence from the Kola Superdeep Borehole and other drilling operations seem to indicate that the rock at a depth beyond several kilometers may be *already* "fracked". [Answer] Almost certainly not. (a) Plate boundaries tend not to be where natural gas is found -- that's normally in older, stable formations and (b) in any event plates are *really big, really heavy* objects and getting plates to do *anything* new in a century or two is likely to be really hard and (c) we can't influence them anyway with anything we now have. It seem plausible that injecting large amounts of water along a fault line might lubricate it enough to release the pent-up stress, but once that stress is released, adding more won't move the plates faster. [Think of the plates](https://en.wikipedia.org/wiki/Plate_tectonics) as really big, really slow beasts that plod along at their own pace (2-5 centimeters/year, typically) without paying much attention to their neighbors. When they rub up against one another going in opposite directions they just keep moving along and their hides stick and slip and stick and slip, but the beasts don't even notice that -- its too trivial to reach their attention. In a fault like the [San Andreas](https://en.wikipedia.org/wiki/San_Andreas_Fault) the plates are moving about 4 cm/year and normally the two sides of the fault are stuck together. As the plates move, the rock along the fault gets more and more bent and stretched and every once in a while the stress builds up so that a small segment of the fault slips on the order of meters to relieve the stress. Bang: Earthquake! Then, a while later (decades, typically) another segment slips and so forth until eventually LA is just west of Berkeley. We might be able to affect *when* a segment slips, but the amount it slips will never be more than enough to release the built-up stress -- and the plates will take no notice of our foolish meddling. [Answer] It would not. Fracking just does not work so deep us to cause significant shifts in the tectonic plates. Fracking depth, in most extreme cases, goes down to about 4 kms. It is more like scratching off a layer of skin to draw blood. The tectonic plates's movements are a different scale entirely. ]
[Question] [ If on a water covered planet, an aquatic species such as the merfolk evolved sapience and now wishes to go into space, how would their spaceship take into account the lack of land? How would a space ship built underwater be able to get into space? My question differs from [this one](https://worldbuilding.stackexchange.com/questions/27761/what-are-some-major-architectural-designs-in-spaceships-for-aquatic-beings) in that I am asking about how the ship would take off and not at all about suits or design. [Answer] When we were first getting into space, we started with very fast, high-flying aircraft. Look at the X series of rocket-powered aircraft used by NASA to test all sorts of things related to space travel. For us, it was a logical step to first be able to get into the air, and then get into space from there. For an underwater species, there would be a third step. Their first phase would be to get out of the water. Once they had the technology to be able to handle working out of their natural habitat, they would have to figure out how to get into the air. THEN would come the leap to space. Given that, it seems logical that the best place to launch a spacecraft for them would be a large floating platform near the equator. The platform would give them access to the air, so any space ship would not have to deal with water, air, AND space, but only two of the three mediums. The equator is good because of the bulge of the planet and our rotation, on earth, it gives a significant fuel savings to launch as close to the equator as possible. Rockets are not implausible. In fact, it seems possible that they might develop rockets before they ever worked out advanced aerodynamic theory. This is because you can create a very simple, primitive rocket by using water trapped in a container that can be heated, forced to expand, and provide thrust. If the species had a reliable source of portable heat, they may have developed the basic principles of the rocket engine long before even being able to build a platform on the surface of the ocean. Water based species have plenty of access to hydrogen if they can generate electricity (separate it out of the water). That is a staple of rocket fuel for us. This all seems to point toward a space program that runs in parallel with our own, at least in general. I am not convinced that they would necessarily put the pieces together the same way though. We had hundreds of years of experimentation with ballistics and aerodynamics (mostly for warfare) under our belt before the invention of the rocket motor. We had a darn good reason to try to develop flying bombs that could self-propel and drop on our enemies many miles away. The military incentive to develop rockets was critical to the entire space effort, from the "buzzbombs" of WWII to the ICBMs that provided the foundational technology for the lunar launch. An aquatic species would have a long history of under water warfare, but apart from using the surface to scout or spy on their enemies, what experience would they have with trying to lob missiles through the air? Why even develop artillery on the surface if your enemy's base of operations is the bottom of the ocean? Necessity is the mother of invention, which means that I bet these guys would be considerably MORE advanced than we were before they actually put all the pieces at their disposal together and built a rocket capable of putting them into orbit. (Remember the motives for us to be in space even now: spying on enemies ON LAND -satellites aren't very good at seeing anything on the bottom of the ocean, which is what they are most concerned about). Ironically, they might develop this kind of technology as a reverse to our own nuclear subs. We keep submarines full of ICBMs under the water because it makes them easy to hide, so we know that no enemy can possibly take out all of them at once. Maybe they want to get into orbit (or the air) for the same reason? Hide their nukes from their opposing nations because nobody pays any attention to whatever is flying around in the sky or orbit. [Answer] Believe it or not, we land-folk have already done something similar! The [Trident-II Ballistic Missile](https://en.wikipedia.org/wiki/UGM-133_Trident_II) (and its ilk) are designed to be launched from a submerged Ballistic Missile Submarine like the Ohio-class or Typhoon-Class. Obviously this is not a rocket intended for orbit, but the principles would be largely the same in either case: accelerate the vehicle until it breaches the surface of the water, then ignite the rocket motors. There are a number of possible ways to accomplish this. From near the surface of the sea the rocket could be pushed using a pressurized tank, much like the Trident does. From the ocean floor it could be accelerated using more traditional motors, driving water jets of some sort. Even some sort of magnetic acceleration might be possible. If I were designing the launch system, I would build a launch platform on a high "peak" near the surface and launch the rocket using pressurized gas or water. The rocket accelerates upward, breaches the surface, and then ignited the engines and off it goes. [Answer] Any water covered planet would have an atmosphere, even if it is made only of water vapour. That's because if you start with an ocean interfacing with outer space, the pressure different will cause water to boil and evaporate. So the best course for your merfolk is building a floating launching station and launch from there. That's because since atmospheric drag should be significantly lower than water drag, launching from air would be cheaper in fuel. Alternatively, a flying vessel could take off from the sea and gain altitude continuously until it reaches space, where it could then accelerate further to establish an orbital path. I don't think this is as efficient as launching a rocket from a floating platform, but then my experience with this method is limited to Kerbal Space Program. I am not a true rocket scientist. [Answer] Depending on the craft shape they could use an underwater launch system. There is a [system](http://www.popsci.com/technology/article/2010-01/cannon-shooting-supplies-space) that in theory can shoot supplies into space and the cannon is mostly underwater. Basically a long barrel (submerged underwater except for the end) is used to fire the spacecraft, like a gun, into space. This type of system would not require land and could be modified to launch various sized/shaped spacecraft. [Answer] So, the other answers make some very good points, though the Trident-II Ballistic Missile isn't a great starting point just as a surface-to-air missile is much easier that a surface-to-orbit rocket. Part of this is due to the stress of breaking from gravity with heavier objects. A missile's payload is significantly smaller than a rocket that is carrying beings and their sustenance (at a minimum). Additionally, though you specify that it's not about suits and design, it makes sense that at a minimum, a substantial amount of water would need to be on the craft for waterborne species to survive, and water is heavy (much heavier than air), increasing power requirements for liftoff and reaching sustainable orbit. Lastly, I agree that having some platform to launch from is nearly imperative as, just like water is heavier than air, water resistance is greater than air resistance, and the force required to launch from even a few hundred feet below surface would be considerably great than from the surface. Especially since, ostensibly, it would be adding a third stage (water-to-surface, surface-to-air, air-to-orbit), meaning more weight and more friction through the water. It's not impossible, but launching from the bottom of the sea would be extremely difficult. [Answer] Would it be at all possible for the merfolks to build a giant electromagnet and launch using a similar albeit smaller electromagnet of an opposing polarity to the second, apply enough energy and the ability to launch seems feasible in my head. I am not a scientist though by any means and do not know if this could legitimately work, but for a sealocked lifeform this also seems better than trying to light a fire underwater. ]
[Question] [ I have a character. One of their parents died. Said parent was cremated, and then - by their own choice; this is a quasi-religious thing - their cremains were mixed into tattoo ink, and the character was tattooed with that ink. The character in question is a paramedic for a religious order, as was their parent before them; before said parent's death, they both agreed that said cremain tattoos would be in the form of writing - specifically writing on various types of first aid, as a memory aid - not for simple stuff like CPR, stuff like "here's how you identify and treat a sucking chest wound", or "here's how you insert a stent". With modern tattoo technology, how small can words written with cremain ink be? This is relevant, since the character in question is trying to pack as much information into as little of a space as possible. [Answer] ## QR Code In a modern setting, one could tattoo a QR code with a link. This link could direct the user to a web-based medical text. This prevents your information from going out of date as medical knowledge changes, and you could set up the webpage / phone to read the procedure upon scanning. You could include QR code links to several common procedures, as well as the equivalent of the manual's homepage. The tattoo for the homepage lets you manually navigate to whatever information you need, meaning the information density is effectively infinite. ## Size You can make QR codes pretty small, but I'd probably keep them ~2x2 inches to ensure that the code remains readable even after it fades, or for when you have to read it in poor lighting, weird angles, etc. [Answer] Tattoos will fade and blur over time, though just how quickly depends on many factors. Some examples [here](https://www.boredpanda.com/tattoo-aging-before-after/). Tattooists are generally reluctant to do small text, because it can become illegible and/or ugly pretty quickly. For instance, one tattooist in [this discussion](https://www.bigtattooplanet.com/forums/tattoo-talk/17407-font-size) says "Unless its very basic single width lettering like handwriting, we wouldn't do anything smaller than about 15mm high" (roughly 42-point font). You might be able to go a little smaller if you're willing to settle for "ugly but readable if I squint". But even at 20-point, the amount of text you could usefully tattoo is probably no more than what could be memorised with a few hours study. And if your paramedics are planning to work with modern protective clothing and gloves, or in dirty conditions, there's no guarantee that *any* tattoo will be usefully visible. It's hard to see this being a good alternative to just putting in the time to learn what they need to know. Note that IRL, medical advice changes quite frequently. For instance, the international CPR guidelines are revised [every five years](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6944876/); a tattoo with that kind of info would very quickly go out of date. Depending on your setting this may or may not be an issue. Rather than using tattoos as a practical reference in emergency situations, it might make more sense to pick something symbolic, if there's room for that in your story. That escapes the need for the tattoo to be visible and it makes information density much less important. [Answer] I would suggest drawing and iconography instead of writing. Essentially if you have ever seen the series Prison Break, one of the main characters have the blueprints to a prison drawn into a full body tattoo. in your case It could be a tracing of all the bones, major blood vessels, nerves etc. for example white for bones, red for blood vessels, and blue for nerves. You can then add iconography to explain different procedures, so need to set a dislocated shoulder, a series of arrows for pull, twist and a line from the arm to the torso so you know where to align the arm before you release. Need to do a cesarean, you have a dotted line where the cut is supposed to be. It should be possible to derive a lot more information from this, than having a direct text that would often be hard to read as it's on some part of your body that is hard to reach. [Answer] **You could make the words small by using shorthand.** <https://en.wikipedia.org/wiki/Shorthand> > > Although the primary use of shorthand has been to record oral > dictation or discourse, some systems are used for compact expression. > For example, healthcare professionals might use shorthand notes in > medical charts and correspondence. > > > There are lots of different shorthand systems. A lot of shorthand systems are phonetic. Here is a translator for Gregg shorthand. <https://steno.tu-clausthal.de/Gregg.php> I put in the first paragraph from your OP and got this: [![shorthand](https://i.stack.imgur.com/EL7xI.gif)](https://i.stack.imgur.com/EL7xI.gif) ]
[Question] [ The society of an island nation is led by a religion known as "The Church of the Eternal Mother", it is an ancient faith that adheres to a fertility goddess. This faith is led by five elderly women called Mannas Natau, at least one of whom will regularly become spontaneously pregnant. These elders are biologically immortal and are worshipped as avatars of the Eternal Mother: mortal vessels of the goddess's power responsible for creating life and growing the numbers of the community. Children born from the goddess are immune to all illnesses and live longer than other humans, but are not immortal. The goal of the community is to ultimately build an empire by conquering its neighbors. The elders have inherited a mutation in their biology which allows them their long lives. Cells during a normal life cycle multiply at a rapid rate, constantly dying and being replaced by new cells. This ability to proliferate doesn't happen indefinitely, decreasing as the individual gets older. Cells begin to produce errors in copying themselves, contributing to the person aging and eventually dying. The reason for the longevity of the elders is due to an immortal cell line, which evades normal cellular senescence and continually undergoes cell division. This ultimately gives the elders their immortality, allowing them to rapidly regenerate from wounds and protects them from natural illnesses. However, their is a natural downside to this. As they age, it becomes harder to produce live children. The amount of stillbirths increase as they get older, to the point where 90% of children are born dead. What role could their natural longevity play in the creation of this problem? [Answer] **Our gametes are not us.** Gametes are not genetically identical to the organism that produced them. They are the haploid products of meiosis, a shuffling of the parent genome and then only half the chromosomes. The elders have some other things going on as well but a large part of their success is one gene and they need both copies of that gene to do what they do. Their descendants have 2 copies because the haploid oocyte duplicates itself in producing the spontaneous pregnancy. But while it is an oocyte it is haploid and it has only one copy. It is just an ordinary oocyte. It has none of the protection that every other cell in this body has. It ages. --- Downvotes! I must unpack this further and maybe these can be tidied up. 1. Gametes age in these immortals because gametes are not immortal. 2. In normal women, age is correlated with increased rate of stillbirths. Older mother = more stillbirths. [Maternal age and risk of stillbirth: a systematic review](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2175002/) This is because the gametes age. 3. Normal women enter menopause before the rate gets to be 70%. These women do not enter menopause because all somatic tissues are immortal and self renewing. Their ova are not self renewing. As those age the rate of miscarriage goes up and up. Ova age and with age comes accumulated mutation, and accumulated mutations are the cause of stillbirths in the real world and in this one. [Answer] Their immune system becomes better and better over time at recognizing foreign elements. Unfortunately, the babies are foreign elements. The number of children they bear is also a factor, as in rh incompatibility syndrome. [Answer] The process you're describing is called *[Parthenogenesis](https://en.wikipedia.org/wiki/Parthenogenesis).* Unless there's something different about their physiology you're not explaining, their children would be their clones... but on to your question! **Eggs become less viable as they get older** There's a fascinating problem with your question: the number of eggs your Elders can carry will always be *finite.* Yes, you could create a rule that says they create eggs as they go and that process, like the process of creating sperm, can go on for as long as the body lives. But that's way to convenient. Let's roll with what we know about terrestrial life: this means your Elders have a finite number of eggs, and that means that a time will come when *they can't spontaneously become pregnant anymore.* That can actually be an interesting issue with your religion. But those eggs! * If the mere mortals were paying enough attention, what they'd realize is that the pregnancies are quite *regular.* The genetics that caused immortality had a side effect: the eggs are released from the ovaries very, very, very slowly. * But immortality isn't perfection. You don't say, but I'm going to assume that your Elders can become sick. Oh, they'll heal quickly just as their wounds will. But they're not *gods.* And since the eggs were all formed naturally from their births and matured to the point of viability at the same time... *they're aging.* * As the eggs get older, they become less and less viable, resulting in an increasing rate of still births over time. It's worth pointing out that your requirement that the rate of stillbirths increases over time is a "non-immortal" thing. That's an important limitation that will make your characters more believable. They're paying a price for their immortality. [Answer] Human Women are born with all the eggs they will ever have. [Link to evidence](https://www.healthline.com/health/womens-health/how-many-eggs-does-a-woman-have) What this means is that, by default, your immortal women will stop being able to get pregnant at all eventually. (Even with endless youth). I think this offers a solution to your problem. Perhaps your immortals have the unique ability to produce new egg cells throughout their lifetime, but that this magical new process that makes eggs later makes eggs that are more likely to be damaged. This would lead to higher a higher change of birth complications later in life when the eggs they were born with have run out and they are using the dodgy new ones. [Answer] We come from cells from our parents. Ever wonder why we start our lives at age zero instead of already having all the cellular aging from our parents? At least in mammals, [it seems that cellular aging is reversed right after fertilization](https://www.sciencenews.org/article/embryos-biological-clock-development). If your immortals' cells don't age the normal way for our species, fertilized eggs may skip a step they need to do after fertilization, and this causes gestation to become unfeasible. [Answer] If you live forever (or very long) you will produce a lot of offspring. If all the offspring is immortal too it can get pretty crowdy. For sure that the genes in the eternals will be restructured to get less children (but to keep the joy of sex!). Maybe in the form of dead children (less children in the form of dead children...Is that correct to say?) On top of that, life will eventually become a bore. This will have its reflection on fertility if its an enduring bore. You could argue that this will increase the urge for new young life but I think ultimately this will take its toll. Death children will be abundant. [Answer] > > What role could their natural longevity play in the creation of this problem? > > > To be absolutely clear, there is nothing 'natural' about their longevity. But it is part of the problem. The Church of the Eternal Mother ([SCP-4476](https://scp-wiki.wikidot.com/scp-4476)) were created by altering adult human females (the Mothers, SCP-4476-1) to make them what they are today. Their longevity, reproduction and so on are the result of alterations made to them by the Grand Karcist Ion. Clearly those changes are genetic as their offspring - those who survive - are also long-lived. Thus it's obvious that the root of their reproductive problems is in the genetics, mixed up in the changes that make their particular form of reproduction possible. In normal humans pregnancy is the result of gametes from both parents fusing to form a zygote. The Mothers have been altered to use [automictic parthenogenesis](https://en.wikipedia.org/wiki/Parthenogenesis#Automictic), where a zygote forms from gametes provided only by the mother. Rather than being strict clones of the mother, automictic parthenogenesis can result in variability of the zygote similar to that seen in classic sexual reproduction. Sadly for the Mothers (but not for the rest of us), the many changes made to their genetic code are simply not viable for the development of a fetus. If a zygote is too similar to the Mother's full genetic sequence it will be still-born. The lucky few that receive only some of the altered alleles - the lesser half of the immortality complex for instance - are able to survive through birth and beyond. They are unfortunately rare, requiring a combination of multiple recessives in specific altered genes. The SCP file notes that there are a high number of birth defects and physical abnormalities, which is additional support for the 'damaged DNA' hypothesis. All is not lost however. The Church of the Eternal Mothers apparently has some ability with genetic manipulation. Their temple itself appears to be a living construct, and on at least one occasion they have created a new mother, apparently using reproductive organs from an outsider. It is possible that in time, and with enough source material, the Mothers could be altered to produce more viable offspring. Let's hope they don't figure it out any time soon. [Answer] Bioaccumulation causes the issues in pregnancy. Bodies of mothers can handle these toxins, heavy metals, radionuclide, chemicals and so on. But developing foetuses less so apart from few lucky ones. Thus early on there is better environment for development and it gets progressively worse as more foreign elements end up in body of mother. ]
[Question] [ I understand that on Earth, we mainly get our helium from natural gas deposits, which traps helium atoms generated from radioactive decay. Would this process still work on a terrestrial planet without fossil fuels like natural gas? If not, could there be another way for people on this planet to mine helium on a commercial scale? [Answer] **You can have helium without hydrocarbons.** You are aware that the process that produces helium is radioactive decay; unrelated to hydrocarbons. Hydrocarbons and helium are associated because people looked for hydrocarbons and underground domes that can trap one gas can trap others too. Recently some people went prospecting for helium, starting with considerations about where there would be rocks that could produce helium and geologic features to trap it. <https://www.chemistryworld.com/news/scientists-unearth-one-of-worlds-largest-helium-gas-deposits/1010122.article> > > Working with Helium One, an exploration company, the team realised > this process is occurring now in the east African Rift Valley, which > crosses nine African countries including Tanzania. ‘We found multiple > places in the Tanzanian Rift where you have geothermal pools,’ says > Ballentine. ‘In that water it’s bubbling gas and that gas isn’t carbon > dioxide, it’s not hydrocarbons, it’s nitrogen with helium contents up > to 10%, which is phenomenal.’ Commercial gas deposits, which contain a > large amount of carbon dioxide and methane, only contain approximately > 0.3% helium. > > > Pretty slick! So too in your world. Helium prospectors would find domes with accumulations of helium. The nitrogen piece is not clear to me and I went digging. If anyone else wants to read up I found a thesis which goes into some detail: <http://etheses.dur.ac.uk/12573/1/Full_Thesis_Danabalan_2017_with_corrections.pdf?DDD15+> I took away that there is a lot of nitrogen underground because there is a lot of nitrogen above ground. Geologic circumstances that trap gas trap nitrogen. Nitrogen is also found with hydrocarbons. If you have a dome that traps helium there will probably be other gases in there with it, but if your world does not have hydrocarbons then none of those. [Answer] If you want to produce Helium, you can always stock on alpha emitters radioactive materials, like Radon, Polonium or Americium: any [alpha particle](https://en.wikipedia.org/wiki/Alpha_particle) is nothing more than a Helium nucleus, which once captured two electrons and dissipated its kinetic energy is ready to use. > > Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. > > > For safe to handle amounts of radioactive material the amount of produced Helium might be negligible, so be ready to use a generous amount of shielding around your production site. [Answer] You *could* extract it directly from the atmosphere. At high cost but with good availability. Admittedly the process would be energy inefficient, as the concentration of Helium is a very low **5 ppm by mass**. But the total reserves are huge. There is a lot of Helium in the Earth atmosphere. In total, some 26800 million tons of the stuff. This figure would be rather similar for any planet with an Earth like gravity and magnetic field. The Helium is not primordial but generated via alpha-decay of radioactives. The magnetic field is just needed to slow down stripping of high exospere Helium by the solar wind, as Helium really loves to go out into outer space. ]
[Question] [ Can a civilization be highly evolved as far as culture, ethics, societal norms, laws, language, literature and arts, but not ever come to develop any sort of advanced technology besides main practical techniques for construction and agriculture? They have a culture-religion that is fully integrated with nature, and they are naturally frugal as they are isolated from the other cultures in their world, and live in a continent that is able to provide all they need to prosper. EDIT: Thanks all for all your amazing inputs. I sort of figured out by myself how to solve this issue I had with this civilization. I will explain it in the end. First, the clarifications: 1. They are not human. They are an intelligent species that evolved from warm-blooded reptiles. 2. They have math (a senary numeric system), literacy (their language is based on clicks like Khoisan), highly developed agriculture, steam, the wheel, levers, pumps, cranes, concrete, highly developed civil engineering and architecture, highly developed metalworks, mining, etc. What I meant by advanced technology was basically war machines, electricity, airplanes, ships, computers, post first industrial revolution technologies. 3. Their philosophical and ethical level is comparable to Ancient Athens/Ancient China but a little more advanced. So, they are basically very enlightened empiricists by nature observation BUT don't have a full empirical scientific method fully developed (and they can't have a western-like scientific method developed, or they will turn to imperialism, conquest and war. That was the main concern behind my question). 4. They have another reptilian species of "companions" (they are "slaves" in the economic sense - work for food and shelter -, but are not slaves in the sense we Americans think of slaves, like some people with another skin color that we can rape, abuse, force to work to death, and beat at will, whenever our White European selves feel frustrated and/or down). That reptilian species has an intelligence comparable to a combination of crows, chimpanzees and dogs. So, they are not able to develop abstract thinking, but are able to learn and execute any sort of tasks the main species need then to do. They also have sets of opposable fingers and toes like the main species. 5. The main species is integrated with nature through their culture/religion as they were essentially hunters gatherers before "the great cataclysm' (something like 70 million years BP). A little before that they had what they call "The 500,000 year march", when they left their original dying (due to basically extinction of resources caused by their own predatory actions) homeland and moved West and then South to this new continent where they been living for 70 million years, totally isolated from the rest of the world. During that "march", their culture of elders/scientists/priests ruling evolved, and they created their literary tradition of passing to the youngsters the knowledge of their whole history, and their nature worshipping religion. One of the main legends is that nature is a live and sentient organism that helps their species by providing and nourishing them. 6. This is another point. They have a culture (like us humans), so instructions needed for survival are not necessarily coded in their DNA like the other animals. They still have some basic survival needs and skills encoded in their DNA (as we still have too, like, for example, fear of spiders, which is not cultural, as all cultures in the world fear spiders), but most of the skills and needs are passed from the elders to the youngsters as culture. So, I basically figured out how to make them highly culturally advanced while keeping them without developing advanced technology and war machines what would have their culture necessarily changing to expansionism, imperialism, conquest and warmongering. I basically used two features from their lore, one geographic (their continent is rich in resources, as well as very isolated) and another cultural (their nature-worship religion). As result, like in Chinese Confucianism, to want to leave their parents/clan homeland is really frowned upon. Whoever leaves their original homeland becomes an outcast and a pariah. As they have all the resources they need, there is no need to trade for resources with other cultures. And as they worship nature, their local rivers, forests, mines, mountains, so forth, are very important to them, so they cannot be faraway from it, and must respect that nature, so not bring destruction or building anything that does not look able to fit into the natural environment. As Ming China, they can have a very advanced civilization, but without any need to contact the exterior world. And, unlike Ming China, they don't need to keep a strong military to protect their borders, because they are separated from the other cultures in their world by thousands of miles of open ocean. Thanks again for all your ideas. And if you have any other ideas that you think would provide any improvement to this way I found to solve this issue I had, I will be really happy to hear them. [Answer] ## Technology is a *prerequisite* for civilization Civilization means cities. The word in fact [has a common root with city](https://www.etymonline.com/word/civil). To have a city requires a lot of assorted technologies. Building materials. Storage containers. Fire. One of the key ones you've identified is agriculture. In order to have cities, you have to have technologies and capabilities that go beyond strategies that will work for smaller-scale communities. Cities need an external food supply, and they need the wherewithal to get the food from the supply to them. ## Efficiency creates more efficiency I saw a very interesting proposition, which I can't find right now, that put one of reasons for the increase in the technological progress rate like this: Very roughly, the rate of technological progress is dependent on the number of people that have surplus time, folks whose immediate demands on their time and attention (subsistence, maintaining infrastructure, manning the army, etc) are not total. See, creating a new invention takes time, often for little short-term practical benefit. The benefits in the long term are astounding - computers, antibiotics, airplanes - but they can take a *very* long time to be realized. [John Dalton](https://www.britannica.com/biography/John-Dalton/Atomic-theory) discovered the atom around 1800 (although a Greek had hypothesized their existence long before). The first [nuclear power plant](https://en.wikipedia.org/wiki/Nuclear_power#First_nuclear_reactor) - a research reactor - came online in 1942. So a society has to be well off enough to be able to support folks that do nothing but pursue pie in the sky technological innovation and especially basic research. And the more of those folks you have, the more technology you have. You can't have a civilization *at all* without people discovering enough technology to make cities work. So you have to have some of them around. And the funny thing is, the more technology you have, the more productivity improves, the society will naturally produce more and more of these folks. (Generally speaking, of course.) TL;DR yes, technological advancement is a natural consequence of civilization. Necessity is the mother of invention. [Answer] **It depends on what kind of person is populating your civilization** Technology really isn't the result of civilization. From a practical point of view, civilization is the result of technology. Here's why. Technology at any level exists because... 1. Someone stubbed their proverbial toe. 2. Then they uttered a vulgar expletive. 3. Then they wondered how to avoid stubbing their toe in the future. Your problem is step #3. It's the natural consequence of a lot of things, including curiosity, desperation, necessity, envy, hatred, love, ... in a word, *emotion.* It's also the consequence of problem-solving, which any good civilization had in their distant past (somewhere back when something large, fuzzy, and hungry was about to prove that you didn't have problem-solving skills). You need to get rid of at least one of those. Possibly both. But the consequence is that you wouldn't have music, religion/philosophy, art, architecture, etc., either, because *that's just another kind of technology.* In modern usage the word is highly focused on *things scientific...* but generally speaking the word expresses skills, development, and an expansion of thought. Attempting to draw a muddled outline of the little grey dude with big eyes who just flew away like a bird is art — but you can't draw it without picking up a burning brand and discovering *art charcoal.* **Conclusion** IMO, your options are... A. People can solve problems, but generally have no motivation to do so (emotionally stunted). B. People can feel the passion of gods, but they can't figure out how to turn left (problem-solving stunted). C. People are somehow *restricted* in that incredibly critical resources (e.g., wood) are nowhere to be found and will never be found, or some irritated god is keeping them from growing as a society by smiting anyone who has a clever thought, or those aliens come back and discover the art wasn't flattering and kill everyone over the age of 11. Some *external influence* that's forcing the people to live a technologically stunted existence. Otherwise, the only things any group of people need to develop technology are crises and time. [Answer] # No, the other way round. Civilization is the inevitable consequence of technology. Specifically, the technology called "Literacy" As soon as a culture starts storing information for future generations, whether by actual Writing and Literacy or via very strict Oral Traditions, that culture starts to gather knowledge. And this gathering of knowledge is what makes civilization possible. And by gathering knowledge, it becomes easier to live, easier to grow, and....easier to gather more knowledge. More people, more knowledge, *is* civilization. [Answer] ## No They're both the result of population density exceeding a critical level. Both to cause and maintain. This goes back to [Gobekli Tepe](https://www.smithsonianmag.com/history/gobekli-tepe-the-worlds-first-temple-83613665/) and the stories that go with it. One of them being that it's the first place where population density exceeded that capable of being sustained by a hunter gatherer lifestyle. The earliest evidence of farming is in the same area in the same period. Civilisation is a relationship between people, the rules of this relationship are dependent on how much people have to interact with each other. You need language, you need laws, you need communication. One person alone can do what they like and need never speak or write, the more people have to interact, the more structure is required, this is the basis for civilisation. As long as the population density never exceeds what your technological level comfortably supports, there's no driving incentive for increased technology, nor the manpower to support it. The aeolipile remains an interesting toy, not a critical proof of concept. [Answer] ## Maybe in the sea I think it is possible, with aquatic species. Ocean is different from land in all the ways that makes rise of sapience possible (hello dolphins), but limits severely what kind of technology they can use. There's no fire, no metals, so your species population density might reach those critical stages where it kickstarts the necessity for regulations, etiquette and so on, in terms of the technology they would be restricted to hunter gatherers or early agriculture at best, since the easy paths that were available for us to start doing stuff like metal smelting would be closed off for them. Do keep in mind though that we really have little idea about how intricate were social and cultural interactions in our prehistoric ancestors. Nothing except physical artifacts remained, and writing was invented only seven thousand years later. I do not think that before "civilization" they were dumb brutes as they often depicted in media. [Answer] **Culture and technology** As stated numerous times now, Culture is created thanks to technology. However, Culture can certainly influence technology and their progress. Culture shows us how we think and thus where we want technological progress, as well as where *not*. Direct DNA alteration has been heavily retarded in it's progression thanks to Culture. Especially on humans there is still a stigma that we shouldn't touch it. The Inca civilization did *know* of wheels which we can see on toys, but for reasons unknown to us they never implemented it more practically. Regardless why, the Culture either stopped this development or it was regarded as not needed. This cultural direction can be taken to an extreme, which we can see in multiple cultures throughout history as well as today. Amish have chosen not to embrace certain technologies, saying that the way they live is correct and shouldn't be defiled by further technology. The dark ages were so long with relative stagnation as the religion stopped technology on multiple levels. Finally, there are cultures in deep forests or islands that haven't changed for generations. Often extra reasons can be given, like small sizes can make it difficult to get many people proposing new technologies and having the time to develop them. Yet this is a part of culture as well. It isn't a stretch that any culture might decide they have the right culture, technology or simply don't think the new ideas are worth it. For whatever reason, new technology will not arise or stick. As per your question. They are integrated in nature, so a steam engine burning nature will not be accepted. These restrictions make it difficult, if not near impossible, to get to certain other stages. Why would they change their life if their current life is plentiful and happy and this is ingrained in the culture? [Answer] **Maybe, if they can overcome population density issues.** The key way to develop all of those civilization issues is to have a very high density of people working together on shared ideas, without them needing to mine the landscape and so gaining greater technology as they get better at mining. As such, you need natural skyscrapers. One way to do this is with [Inosculation](https://en.wikipedia.org/wiki/Inosculation) where you can grow trees together. This civilization could have very advanced tree growing techniques where they can grow trees together to form houses and homes and platforms for their homes. The trees could naturally provide a large bounty for them. As such, they could have huge cities of tens or hundreds of thousands on shared trees, without having any technology that is useful on a scale of less than years. **The main problem is working out how they handle conflict and danger.** They can be peace loving sure, but what happens when a hostile pest destroys their food stocks, or a natural disaster wrecks their home, or a plague kills their people? When times are tough, people often resort to war to get new resources, no matter how peace loving. For this I would suggest [flower war.](https://en.wikipedia.org/wiki/Flower_war) Rather than having costly and large engagements, small fights between mostly nobles and some commoners would be the norm. You meet on a set date, fight with proven weapons, and whoever is more skilled in melee combat wins. You can trade resources based off this. This would prevent the need for large scale costly wars which would advance technology. [Answer] Technology per se is a rather broad term. You can have civilization without certain technologies. The Mayas had a fairly developed civilization with respect to weapons, astronomy, religion, architecture and agriculture, all advanced to a quite good level. Despite that they never came out with the technology of a wheel for transportation, which I would say it's at the base of the practical techniques. So, yes, it's totally plausible. [Answer] > > Can a civilization be highly evolved as far as culture, ethics, societal norms, ***laws***, language, ***literature*** and ***arts***, but not ever come to develop any sort of advanced technology besides main practical techniques for construction and agriculture? > > > I've added emphasis. How do you expect your civilisation to produce writing, drawing sculpting etc materials without technology? And what is the need for a complex set of laws when only a few hundred people who the land can support in proximity can interact? Does your technology level of "agriculture" include food storage? Processing of fresh food into preserved forms for winter? Transport of foodstuffs? The other issue is that if there is a similar civilisation nearby which has also developed all of these items, but has additionally developed weapons, then your civilisation will not last long before it is attacked and its resources are captured. However it is feasible, and has happened in the real world, that a geographically isolated civilisation could last a very long time with just enough technology to meet current needs whilst focussing on developing literature and arts. You will still need to think about how it would cope with unexpected events: famines, earthquakes etc. if there is little culture of problem-solving and technological development [Answer] ## Technology far predates Civilization (and construction and agriculture) Assuming a standard definition that nearly all scholars use for technology, it has existed since humans could first reasonably called humans, and probably even before that. Technology is: > > Technology is the sum of techniques, skills, methods, and processes used in the production of goods or services or in the accomplishment of objectives, such as scientific investigation. > > > ... > > The simplest form of technology is the development and use of basic tools. The prehistoric discovery of how to control fire and the later Neolithic Revolution increased the available sources of food, and the invention of the wheel helped humans to travel in and control their environment. > > > Basic tools date back to [2.6 million years ago](https://humanorigins.si.edu/evidence/behavior/stone-tools#:%7E:text=The%20earliest%20stone%20toolmaking%20developed,cores%2C%20and%20sharp%20stone%20flakes.). The earliest civilizations are only [thousands of years old](https://en.wikipedia.org/wiki/Human_history#:%7E:text=Sumer%2C%20located%20in%20Mesopotamia%2C%20is,script%2C%20appeared%20around%203000%20BCE.). ## With that we can easily answer the question: > > Is technology a natural consequence of civilization? > > > and > > Can a civilization be highly evolved as far as culture, ethics, societal norms, laws, language, literature and arts, but not ever come to develop any sort of advanced technology besides main practical techniques for construction and agriculture? > > > Technology is obviously not a consequence of civilization, it far predates it. Moreover, it is unthinkable that you would have civilization without technology, even with the caveats given. The technology used to create construction and agriculture would inevitably lead to those techniques being used for other things. We can see that tools were used millions of years before construction and agriculture were even conceived. [Answer] ### Maybe, in a magically-powered fantasy universe with inconsistent physics. In fantasy world where the laws of physics behave in an inconsistent fashion but there is sufficient amounts of magic to allow life to function despite that, it might be possible that a society doesn't develop much if any technology if it relies primarily on magic instead. For instance, if smelting iron ore into a consistently usable form isn't possible without magic, then they probably won't use non-magical iron tools. If gears randomly jam up and break, then you won't have clockwork or watermills. If refining flammable oil is as likely to result in an explosive as lantern fuel, then you won't see any oil lanterns. [Answer] in my opinion, i think its possible if we are not talking about human as the focus, but alien lifeform or other animals society, especially if they cant manipulate tools and depend on group work. for example ant and bee, at least from quick google they are considered as civilization with their society, and i think ant are quite advance regarding agriculture/domestication and building, but they dont develop any tools as far as i know, and only using their body feature or ability including using their larvae silk to glued the materials in case of weaver ants. i dont know why mine get downvote, after seeing OP edit it turn out not about human anyway and mean electronic technology specifically, but here copy paste some answer from [quora](https://www.quora.com/Do-ants-have-civilization), also i want to remind ppl that OP originally is fine with advance agriculture and architecture technology. > > I. Embryonic civilizations, which still only possess the basics of the elements of civilization (although they are still very advanced; > the Sumerians were embryonic and are famous for being the first > civilization and for being advanced) > > > II. Advanced civilizations, which feature advanced elements of the > keys. > > > The five key elements of civilization are: > > > I. Centralized Government > > > II. Organized Religion > > > III. Job Specialization > > > IV. Social Classes > > > V. Arts, architecture, writing > > > We can assume from this point that the ants are an embryonic > civilization. > > > Ants and Technological Advancement > > > Fun fact: Did you know that ants discovered agriculture? For millions > of years, in fact, ants have developed the skill to grow, harvest, and > eat several small plants. > > > Other fun fact: Ants & Vassals. > > > A vassal kingdom is an otherwise independent country which pays > tribute to a greater power. Tribute is essentially, in historical > cases, a portion of supplies and manpower. Vassals would pay their > rulers in soldiers, food, or labor. One species of ants, called > Slavemaking Ants, literally invade colonies and take 10% of their > larvae every month or so. This larvae is carried home and raised like > the slavemakers’ own children. These ants, after being birthed, > genuinely think that they are part of the colony, even if they’re > another species of ant, and will then join their kidnappers in raids > against even its home colony without any memory. Slavemaking ants use > this strategy to boost their numbers. > > > Social Heirarchy: > > > Simply put: > > > Queens—Alpha & Beta Males—Soldiers—Omega Males & Females. > > > Every ant knows its place. > > > Religion: > > > A hive mind, one could potentially argue that ants worship their > queens as if they were deities. Like chimpanzees, they cold > hypothetically possess a very primitive spirituality. Chimp religion, > however, is still under research. > > > Architecture & Arts: > > > Ants all have one uniform colony style: Tunnels and mounds. Larger > queendoms can be several interconnected mounds spanning multiple > acres. One of the largest ant Queendoms of all time, located in Japan, > spanned over 640 acres and possessed 45,000 different anthills. Its > population could’ve consisted of as many as 306 MILLION ants. > > > [Answer] Yes, technology and advanced civilisation are not related. The most advanced civilisations may have no recognisable technology and be completely integrated with nature, working with it instead of against it, without war, crime, poverty or hatred. Other cultures will sneer at them as mere hippies, or decry the entire concept as a reversion to the 'noble savage stereotype' ...while secretly envying their relaxed lifestyle. ]
[Question] [ An intelligent race of shapeshifter came to settle on present day Earth, they managed to clear the custom and are placed on 24hr monitoring by MiB agents. It is illegal for them to expose their kind to us so they took on a human appearance and learn mannerisms and etiquettes before mingling with the public, they learn to excrete water in the forms of tears and drool and even appears to perspires under hot weather. I'm wondering how about blushing when the shapeshifter tried to increase their own blood pressure only to turn blue or green which could catch unwanted attention? What's the most economic and elegant way to blush like a normal person for these blue blooded shapeshifters? [Answer] **Might be possible** Lots of creatures can change the pigment of their skin. If it's a shapeshifter, I would expect it can change it's skin like a squid. They are famous for their incredibly detailed and very difficult to distinguish camouflage. <https://youtu.be/PmDTtkZlMwM> If you want just blood pressure, maybe something that pushes different kinds of pigment/red coloured cells with higher blood pressure, allowing for different kinds of colour at more or less correct blood pressure levels. [Answer] **Chromotophores.** I'd imagine your shapeshifter has some chameleon like qualities in order to help them...um...shift! > > Since chameleons can't generate their own body heat, changing the color of their skin is a way to maintain a favorable body temperature. ... Beneath this are several more layers of skin that contain specialized cells called chromatophores. The chromatophores at each level are filled with sacs of different kinds of pigment. > > > [Source: Wired](https://www.google.com/amp/s/www.wired.com/2014/04/how-do-chameleons-change-colors/amp) Blushing would be second nature to them, they wouldn't need any special training in order to blush...maybe training in order not to blush too frequently. [Answer] If they can willingly alter their appeareance to a huge degree, then blushing a little should be second nature to them. An example, you wouldn't ask how the T-1000 form Terminator 2 can blush. He's already making a liquid metal look like human skin, he can clearly make it look like human skin that's a little redder. So if your shapeshifters are already changing form a creature with different colored skin or without something that resembles humas skin, they already have solved most of this problem. Even if your shapeshifters have more modest abilities, there are a nomber of things they are probably already taking into account that would be a lot similar to blushing. For instance, are they simulating skin marks, pimplies, freckles, other imperfectons? Are they capable changing into people with different body types? Our skin donest look the same in every art of our body, look at out palms and the back of our hands, for instance. There's also the effect of the sun on the more exposed skin. Whenever a shapeshifter changes, they'd need the reight colored skin in the right locations, that mastery of their skin tone could be extended into blushing. How they actually change the color of their skin, there are many posibilities. Manipulating pigments on theit skin would be an example, as EveryBitHelps mentioned. Then again, I would say it has to be something in tune to thier general shapeshifting abilities. If you already have that figured out, then adding blushing on top doesn't seem that complicated. If not, then I don't see why just focus o the blushing science. Unless you are going for how to prevent an unconcious raise of blood pressure single them out. Then the shapeshifter would have to learn to identify the change and compensate. Or they could just shapeshif a thicker or more opaque skin. That never let's the underlying blood show through. This would help other issues as well. If the undelying blood is contributing to the color of the skin, then the skin has a redder base tone by itsef. That means that when blood rushes out of an area (think when to press some part of your skin hard), it turns whiter in humans but it'd be the opposite effect for your guys. [Answer] **The opposite of blue is red.** Unless you are looking at a pure frequency, for any color, the perceived color is the result of a mix of colors contributing to the end color. Blushing means more blood in the skin and increase in contribution of red to the end color. The converse happens if someone is really cold with blood leaving the skin and going to the core. Without the red to balance, the (fair) skin of the cold person looks more blue. For a blue blooded creature, removing a degree of blueness renders the skin relatively red. Consider this comely alien and her color inverse. [![red and blue](https://i.stack.imgur.com/CKlxH.jpg)](https://i.stack.imgur.com/CKlxH.jpg) Assuming these shapeshifters are fair skinned at baseline (not black or brown or blue), to achieve this they must have a baseline balance of blue and red in their skin. Withdrawing some blue will result in a relative increase of red, just as in a cold fair skinned human withdrawal of some red results in a relative increase of blue. It leaves open the question of why shapeshifters might not take on any color they choose. Presumably it must take some time to finish a shape, which is then difficult to modify on the fly by the same mechanism. [Answer] # Drink Kool Aid If you have a lot of silver in your system and you can't get rid of it fast enough, you become blue. This is a condition called Argyria and usually happens to people who take medications containing silver. Your aliens can do something like that, but using a red coloring agent instead of a blue one. People on Earth are known to have dyed their hair red with Kool Aid (which makes me wonder what that poison does to your inner organs). Perhaps by drinking enough Kool Aid your aliens can dye their internal fluids red from inside out, thus being able to pass as a human when blushing. [Answer] Several answers suggest there's a solution if the species is a chameleon. If they aren't chameleons, however, they might use technology. It might be that they tattoo themselves with a material that binds to the blood vessel walls and exhibits this chameleon like behavior when the blood vessels dilate, exposing a red-colored pigment when stretched. This is technically more simple than that of a chameleon because it only needs to generate one response to one stimulus. It only needs to get one color right, rather than a rainbow. ]
[Question] [ ## Question: does a liquid or gelatinous substance exist that once outside a body could solidify and be hard enough to be used once as a tool? The **setting** is low fantasy without magic, yet with creatures that went down a different path in evolution due to hard environmental pressure. --- **What I want to achieve** I want a creature to be able to make impromptu tools with materials from inside their body. The solidifying process should start once excreted and be done in seconds or minutes, hours would kill my intentions. They result does not need to be durable, a single use is enough. Basically a biological prototype 3d printer with limited use. --- **Is that possible without making up some fantasy substance/material?** I looked into crystals and solidification but didn't find anything convincing. Sadly they take way too long to form. If such a substance exists it would be nice if you could state whether there are conditions that need to be met like pressure, heat/cold/electricity or some kind of material that the creature must ingest. The creature can have some special attributes in order to meet these conditions but this is for me to handle. Im kinda worried that such a solidifying process would generate heat or somewhat pain but im not knowledgeable in this field. **EDIT:** Mixing two substances or adding another external factor to harden is a legit approach. Most important is the hardening speed as it needs to be solid in seconds. The result can be crude and only useable once. Fine Detail is not needed. This process would not replace the normal way of making objects, but help in special situations. [Answer] I expect a two-component [epoxy resin](https://en.wikipedia.org/wiki/Epoxy) will work best, like two-component glue that hardens quickly when mixed, or the material used to make light boats float when capsized. When kept separate, both components are liquid, but once mixed, they quickly harden. [Thiols](https://en.wikipedia.org/wiki/Epoxy#Thiols) react quickly with epoxides at room temperature and might be the answer you are looking for, though you should consider the toxicity of exopy. [Answer] Spider silk might be useful. Although usually associated with thread structures there is no reason why it should not be wound or otherwise deposited into other shapes. Spider silk comes in a wide variety of types with various properties It can be sticky or not and some silk has exceptional strength. But whatever organism produced it would have to have the capacity to store a large amount of it for such uses. [Answer] ## Spider Silk + Resins Many different tree resins will polymerize upon drying and are used to make adhesives and varnishes. Combine something like that with a large number of spider-like spinnerets and you have the makings of a biological equivalent of carbon-fiber. Not necessarily the best if you want to make a hammer, but you could always incorporate a convenient rock or other found material to add some density to it. [Answer] ## There isn't one, the problem is you are not just looking for a fast phase change, but a fast phase change in a controlled manner. There are a lot of ways to make a material quickly there are far fewer ways to **shape** said material. No matter what you use you are still limited by how fast the material can be produced and moved, a biological system cannot produce significant quantities of material quickly. Even using epoxies you get one tool from stored material then have to wait days for the next. On top of that the faster you want it to form the cruder and less precise you can make the tools, an epoxy cast in a shapeable sack in the body is just going to be a lump in the rough shape of a tool, if you use precision deposition to get a precise shape you are back to taking hours to days because you are limited by cell migration speed. You could use a lattice of specialized epoxy filled cells but it will flimsy and take forever to regenerate. Making a solid mass is easy making a controlled shape is hard. worse the caloric cost of such an enterprise makes it so it can't evolve since it uses vastly more calories than you can harvest from a single tool in the short term. this is why using manufactured tools is so favorable, very small caloric investment. [Answer] This is like an answer and like a comment on all the other answers. I specifically want to address the shaping challenge. The creature’s ability to naturally spit resin is probably an offensive talent, meant to spit in the face of opponents and prey. That likely means that the carapace has evolved to be non-stick to the same resin. Or the carapace can secrete an oil as needed to keep it from sticking. This makes it a great mold substance. You need a form factor for the epoxy or resin to harden inside if you want to create tools. Why not have the creature use its own carapace? Suppose your creature has body armor. As they became civilized, there’s less need to maintain the armor to be combat ready. So they can carve shapes into it. You can make a reasonable hammer shape on a thigh. You could make a blade shape on a forearm. A fixed-length ruler, or even parts for a slide rule on the other arm. If you drill sideways into the carapace, you could create shafts that allow for spikes, nails (like for setting up a tent). The carvings are like tattoos. The creature has to have picked their tools over lifetime. [Answer] For a number of reasons described in the other answers, I think you'll have a hard time coming up with a solely biological process that accomplishes this. If you expand the requirements a bit, though, you'll have a lot more options. Instead of placing the onus on the creature's biological systems, incorporate the environment as well. For instance, the creature could produce a fluid that when mixed with sand and kneaded together, causes it to set up and harden like a cement (some insects build nests this way). Or, if it produced a sufficiently acidic substance, it could use that to dissolve/etch certain minerals (like limestone) to shape them into tools. In these sorts of cases, most of the mass of the tools comes from the environment. Your creature only has to produce the reagent necessary to convert the raw materials into something sufficiently tool-like. [Answer] Epoxy resins and glues often start to polymerize when exposed to outside moisture, while they stay liquid as long as they are in their tube protected from water molecules. Yes, their reaction is exothermal, else it won't spontaneously happen. If you ever left a glue tube open, you know that they turn pretty quickly into a solid. The reaction rate can be tuned by adding proper addictive: when you glue two parts together you don't want to hold them pressed for hours, nor you want the glue to become so hot that it damages the parts. If you ever spilled some rapid glue on your finger as a kid, you probably remember that it took seconds to set and that you could feel some warmth, but you got no burns. [Answer] The resin that dentists use for "white" fillings might be regarded as a proof of concept. For the dentist's convenience, this resin remains soft until setting is catalyzed by blue laser light. It is also anti-catalyzed by oxygen, so a thin surface film of a few molecules always remains un-set. This is so another layer of resin can be placed on top (thereby excluding oxygen) and the layers bonded together by the laser. It's hard and tough enough to be used as a tooth for decades. So all that is needed is to replace the blue-light catalyst with a chemical catalyst added at the time the material is excreted. Or perhaps a greater degree of photo-sensitivity, and the creature can only use this excretion on a sunny day. A hundred million years of evolution might well create a better resin than a few human chemical engineers have managed in a mere few years. [Answer] Apart from epoxy resin, that is already mentioned there's another option. ### Photo sensitive resin This is a thing that is used in experimental 3D printing (google it, it's cool). If your creature can excrete tool-shaped blob, this blob can easily solidify in sunlight. Advantage is that you only need one component, but the solidification may take longer and it won't work at night. But the fact it doesn't work at night can be useful from storytelling perspective. [Answer] Gallium is completely liquid above 85°F, and once it's below about 75°F, it's about as hard as "cold candle wax" (according to one guy who's played with it a while). While this wouldn't be hard enough for a spike or a bolt, it could be used to make some keys and locks, gears, or bowls/plates/cups (just avoid hot soup!). [Answer] <https://en.wikipedia.org/wiki/Non-Newtonian_fluid> What you may be looking for is a non-newtonian fluid. Most famous examples are things that go from more fluid to less fluid when under pressure as they work well as armour. They do however go in the other direction - with the ability to become more fluid under pressure; and also can work with time. This means that if the body were to keep an amount of this non-newtonian liquid under pressure; it would remain a liquid; but on release; would become more viscous to the point of seeming like a solid. For most of these fluids, the process is not one way; meaning that if it gets put in the same conditions again; it will return to being as viscous as it was. So while this could be used as a tool; one might not be able to use it to apply much force on anything. [Answer] As John's answer points out: There are many issues with resin epoxies as most other answers suggest. They are very hard to shape and biologically reabsorb, this makes for major recyclability and production issues. While shaping the thing could probably be overcome, it takes a lot of calories to create a resin tool compared to picking up a sharp rock or a stick: this makes it a very unlikely adaptation to evolve unless you can eat it when you are done with it. **A better solution might be something more like ABS plastic** ABS is an organic plastic that could just as theoretically be derived from organic compounds in a 2-part epoxy like process. It's not as hard as resin epoxy, but it is still hard enough to make many types of crude tools out of. The major reason for using this softer plastic is that it can be easily shaped and dissolved by another organic compound: acetone. Acetone can be used to shape, smooth, and mend ABS plastics <https://www.youtube.com/watch?v=Pm3Yn6XKufg>, <https://www.youtube.com/watch?v=2YIV0XVkkPE>. So, instead of trying to spit out a fully finished tool with resin, your animal could spit out a clump of ABS in the rough shape it needs, then excrete acetone to mold the plastic in its hands like clay until it is the right shape. In this manor you meet the need for quick ad hoc tools without needing molds to cast them in. When your animal is done, it just eats the plastic using acetone rich saliva. At 0:27 in this video: <https://www.youtube.com/watch?v=AM3rl1JFsuY>, you can see just how quickly acetone can dissolve large ABS things, meaning your animal can recover a lot of the lost calories pretty quickly and easily just like a spider that eats its own web. ABS is strong enough on its own to make many simple tools: wrenches, cultary, water bottles, shives, etc. In cases where your animal needs something with more heft like a hammer or chopping ability like a an axe, it would still make a good handle making material so you could just pick up the rock you need and let your spit do the rest. [Answer] A sharp edge could be formed by first producing a round-shaped blob of an epoxy-like substance and then, once it has solidified, shattering it into pieces. Some of the pieces can have blade-like edges, so they can be used like a knife or a dagger. An abrupt change in temperature could help to break a blob of solid substance that is otherwise hard to break. E.g. the creature has a high internal body temperature but lives in an arctic region. It produces a blob of epoxy-like material inside its body and then throws in the snow, where it breaks into shards. ]
[Question] [ I need to wipe out a city. Not a huge one (I won't let them grow beyond a certain limit), but big enough to need to do some pretty serious damage. Let's say something similar in size to Pompeii. (yes... *that* Pompeii...) My weapon of choice is a meteor. Carefully aimed, let it meander the heavens for millions of years and then ----***blam!***---- right on target at the appointed hour with no need of any further intervention. Clean, clinical, and no side effects. Only there are side effects, aren't there...? Oh sure, a nice small meteor can make a beautiful explosion and a nice crater for itself without really having any effect on anyone outside the blast radius. But when you scale up, a bigger meteor will not only make a crater but also mess with the local or even global climate, maybe even trigger tsunamis, earthquakes, volcanoes... Argh! I don't want any of that. All I want to do is wipe out a city with a giant space rock, but leave everything else untouched. No collateral damage. Is that really too much to ask? Ideally, I'm hoping for a lone survivor to get away because he just happened to be leaving the city immediately before the event (uh... because I'll tell him to. Hope he listens!). The exact distance away isn't important, but he needs to be able to turn around at the right moment and see the impact close enough at hand to know exactly what happened but without getting caught up in it himself. [Answer] **Keep it small** **First**, we need to know the area that must be destroyed: > > Pompeii covered a total of 64 to 67 hectares (170 acres) and was home > to 11,000 to 11,500 people > -[Wikipedia](https://en.wikipedia.org/wiki/Pompeii) > > > So you need a radius of total destruction of only about 400 m. That's very small. **Second**, let's look at the equivalent kind of nuclear detonation will have a 100 % casualty radius of about 400 m. For this, I used <https://nuclearsecrecy.com/nukemap/> At a ground burst of 6 kilotons: > > Air blast radius (20 psi): 400 m (0.49 km²) > > > At 20 psi overpressure, > heavily built concrete buildings are severely damaged or demolished; > fatalities approach 100%. Often used as a standard benchmark for heavy > damage in cities. > > > (6 kilotons is wee. The Hiroshima bomb was 15 kt) **Finally**, we need a bolide collision that generates about 6kt. [This impact calculator](http://down2earth.eu/impact_calculator) doesn't even go that small. Happily, [This one](http://www.convertalot.com/asteroid_impact_calculator.html) does. Let's assume the bolide has a density of rock (2 g/cm³), a graze angle of 45 degrees, and a poky velocity of only 12 km/s (you can massage those numbers to get the effect you want). A 7 m (23 ft) diameter bolide will create a 6.1 kt explosion. It will create a 69 m diameter crater, and you can assume that everybody within the city wall would be killed by the blast effects and the buildings falling in on top of them. For fun, let's bump it up to 10 m (33 ft) and 25 km/s. That's 78 kilotons, the crater is 150 m, and you just blew down those sturdy city walls and incinerated the fields and orchards outside. Be careful of going too big or too fast. **Extra credit**: Lots of meteors explode or fragment before reaching ground, so that 7 m lump might be a fragment of something larger. [Answer] > > Let's say something similar in size to Pompeii. > > > This sounds like a job for [nukemap](https://nuclearsecrecy.com/nukemap/). [![15kt surface blast on Pompeii](https://i.stack.imgur.com/y2m2L.png)](https://i.stack.imgur.com/y2m2L.png) Here's an [example detonation of a 15kt yield device](https://nuclearsecrecy.com/nukemap/?&kt=15&lat=40.7480373&lng=14.4992065&airburst=0&hob_ft=0&fireball=0&crater=1&psi=20,5,1&rem=&therm=&zm=13), equivalent to the "Little Boy" device used on Hiroshima. The effects of a surface blast are shown, without showing thermal effects which will be quite different for a meterorite impact than for a nuclear explosion. As you can see, the inner grey circle (the 5psi air blast radius lies at about 1.13km from ground zero, a little over two thirds of a mile. Within that radius, you can reasonably expect most residential buildings to be pretty badly smashed up. The outer grey circle is the 1psi overpressure radius where things like glass windows can still be smashed and lies at about 3km. If your observer was outside this radius, they've a good chance of surviving alive and intact. There's a wealth of information on nuclear blasts of this magnitude on the interwebs, including videos. In all cases you can see that whilst 12kt is a pretty fearsome amount of destructive power, it pales in comparison to larger bombs or natural disasters like volcanic eruptions. You need not expect climatic change or huge chunks of debris being thrown for miles. --- What's *more* difficult though is to work out exactly what kind of impactor would cause this very specific kind of devastation. Fiddling with the [Earth Impact Effects Program](https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/) (also referenced by L.Dutch above), you may find (as I did) that its trick to find a set of parameters that allows a significant amount of damage to the ground within the desired sort of radius, without having a massive airburst (widely distributing the damage, or expending too much of the energy too high up). I came up with [this set of parameters](https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=1&distanceUnits=1&diam=4&diameterUnits=1&pdens=22560&pdens_select=8000&vel=11&velocityUnits=1&theta=45&wdepth=&wdepthUnits=1&tdens=2750), which involves an iridium asteroid (unlikely, but not impossible) to concentrate a lot of mass into a small volume. Note that the EIEP authors caution against using densities greater than iron, as they may result in unrealistic object strengths, caveat impactor etc. Iron asteroids (much more plausible) tended to break up, or deliver insufficient *oomph*. There will also be differences between the calculations used by nukemap and EIEP so the results aren't *entirely* comparable, but then hitting rocks together *really hard* isn't the same as a nuclear fireball, so there you go. The exact details will depend on the effects you want. A low-altitude airburst (like [this one](https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=1&distanceUnits=1&diam=3&diameterUnits=1&pdens=&pdens_select=8000&vel=11&velocityUnits=1&theta=45&wdepth=&wdepthUnits=1&tdens=2750) using a smaller iron meteorite) would look neat, and provide a shotgun-like effect that distributes the damage across an area destroying everything underneath it but not producing as much collateral damage. An object that arrives intact, on the other hand, will leave a big bad crater behind. You can decide what you'd prefer. [Answer] I think you can bail out of this problem with an object similar to the one which created the [meteor crater](https://en.wikipedia.org/wiki/Meteor_Crater) > > Meteor Crater lies at an elevation of 5,640 ft (1,719 m) above sea level. It is about 3,900 ft (1,200 m) in diameter, some 560 ft (170 m) deep, and is surrounded by a rim that rises 148 ft (45 m) above the surrounding plains. > > > Though the crater itself is smallish, the impact had consequences on a larger area: > > The object that excavated the crater was a nickel-iron meteorite about 160 feet (50 meters) across. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at up to 45,000 mph (20 km/s) but more recent research suggests the impact was substantially slower, at 29,000 mph (12.8 km/s). It is believed that about half of the impactor's bulk was vaporized during its descent through the atmosphere. Impact energy has been estimated at about 10 megatons. The meteorite was mostly vaporized upon impact, leaving few remains in the crater > > > The vaporization of the meteor would create a nice heat blast, and the following impact and debris deposition would wipe out a small city like the Pompeii you refer, without any dramatic large scale effect. > > The impact created an inverted stratigraphy, so that the layers immediately exterior to the rim are stacked in the reverse order to which they normally occur; the impact overturned and inverted the layers to a distance of one to two kilometers outward from the crater's edge > > > If you want to get a clue of what the impact felt like at various distances, you can use one of the many online impact calculators. I usually refer to [this](https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/) [Answer] **House-sized meteor. City-sized crater.** A good starting point is the nuclear bomb that dropped on Hiroshima. The blast was city-sized as opposed to country-sized. It had about $6 \times 10^{13}$ Joules of total energy.$^1$ So we know that's not enough for significant secondary effects. We want a meteor with a similar energy total. The kinetic energy of the meteor is $\frac{MV^2}{2}$ for mass $M$ and velocity $V$. We want $\frac{MV^2}{2}=6 \times 10^{13}$. [This](https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/1999RS002283) paper (page 1214 and onwards) says meteors enter the atmosphere at $20$-ish kilometres per second or $V = 2 \times 10^4 m/s$. Squaring that we get $V^2 = 4 \times 10 ^8$. Plugging that in we get $$\frac{M }{2} (4 \times 10 ^8) = 6 \times 10^{13}$$ $$ M (2 \times 10 ^8) = 6 \times 10^{13}$$ $$ M = 3 \times 10^{5}$$ As usual $M$ is measured in kg so the mass should be $300,000$ kg. In other words $300$ tons. So we're looking at a house-sized meteor. The second question is about your survivor is more about the shape of the blast. I would imagine the amount of material thrown into the air will be MUCH larger than the city. So "viewing the explosion from the top of a nearby hill" is out of the question. More realistic is "caught on the edge of the blast front." Something like [this](https://www.youtube.com/watch?v=4HKYkeAOQiE) but on a smaller scale, where a tsunami of dust and soil moves outwards from the impact. Granted our meteor is MUCH smaller. But the survivor is also MUCH closer. (the dinosaurs in the video are on the other side of the planet). $^1$ Granted only a small portion was directed into the city. I imagine the meteor will be much more efficient if it physically impacts the city. Some energy will be burnt off in the atmosphere but I don't know how much. **Edit:** The [impact calculator](https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=20&distanceUnits=1&diam=5&diameterUnits=1&pdens=&pdens_select=3000&vel=20&velocityUnits=1&theta=90&wdepth=&wdepthUnits=1&tdens=2500) talks about something called an airburst, which is the explosion caused by the meteor smashing into the thickest part of the atmosphere. It seems larger bodies airburst closer to the surface and lost proportionally more of their energy in the burst. That means larger impacts are less *focused* towards the ground. [Answer] As noted, Barringer (Meteor) Crater provides an easily observable benchmark: a 1.2 km crater would be the result of an explosion large enough that you could assume everything within tens of kilometers would be flattened, and right there is even a very large modern city. For another comparison, Tunguska. The airburst was somewhere between 10 and 30 megatonnes (estimates vary), but flattened roughly 2100 km2 of forest despite exploding at between 5 and 10 km above the surface; that type of overpressure would devastate the majority of urban structures near the center of the explosion. The Castle Bravo test accidentally went into that range, and it vaporized instruments and destroyed bunkers *designed* to be hit by a nuclear explosion, so you can image what normal civic infrastructure would look like. [Answer] Something like the Tunguska event might be suitable. I believe directly under the blast trees were left standing so someone in the city in a deep basement might well have survived <https://en.wikipedia.org/wiki/Tunguska_event> [Answer] You could potentially get away with destroying a larger city with a smaller meteor if you took advantage of a knock on effect from something else being destroyed. An example of this: A very large dam upstream of the city is destroyed by the meteor, causing a catastrophic flood that washes most of the city away. ]
[Question] [ I have been toying with the idea that *all* oceans are gone. Underground water still exists but the Earth has essentially turned into the planet from Dune. My characters all live / survive out where the oceans once were as it's the closest source for water. The Earth is now just one big desert. My question is, instead of 100% of all surface water gone, is 90% more feasible? I plan on having larger civilisations, mining towns etc. I want water to be a rare commodity, but not so rare that only 5 people can live off it. As the majority of the story takes place out in these vast oceans of desert, there are going to be some large swathes of distance in-between continents / countries. Initially people were going to get around on horse back, but there's too much distance for a horse to travel, then I considered intercontinental railroads but that is taking technology in a direction I hadn't planned on going. So, if I leave a small portion of the ocean, travel by boat could seem plausible. [Answer] There are a number of issues with eliminating our planet's oceans... Our planet's gravity holds onto our water pretty tightly. The energies needed to evacuate several oceans worth of water out into space would probably also take our atmosphere along for the ride. You could send the water deeper into the planet's crust, but that leads to other issues... [50-85% of our oxygen comes from phytoplankton which live in the oceans near the surface.](https://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen) Eliminate the oceans (or even just poison them badly enough) and that oxygen goes bye-bye. Similarly, if the water submerges deeper into the crust, the percentage that remains near the surface will decrease greatly, leaving less room for the phytoplankton. So no matter where the water goes, oxygen will be in short supply after it is gone. To combat the oxygen loss, you could evolve the phytoplankton to no longer require an aquatic environment. They could continue doing their job for us, living off of the nutrient rich silt and rotting fish corpses which cover the newly exposed ocean floor. That would give you a green and smelly desert, but at least your characters would still be able to breathe. There would be other issues such as climate change and storm intensification. We might even discover that the former ocean waves served a hidden function, absorbing momentum from the winds which would otherwise rise to constant storm force everywhere. Your ocean-less planet is quickly transforming into a literal hell on Earth. Earth would undoubtedly survive without its oceans, but its current infestation of organic life would probably not remain upon it for long. [Answer] The single biggest issue you'll face is the loss of thermal mass. One of the key reasons that deserts are so hot during the day, so cold at night is that there's no water that soaks up the heat and releases it slowly through the night. In your world, this is now the norm so your days will be extremely hot, and nights extremely cold. Within the bounds of habitability? With underground homes, perhaps. I wouldn't want to be living on the surface though. Water in such an environment is very precious, and your inhabitants will most likely have mechanisms similar to those described in Dune for rendering water from the dead and other biological material for re-use. Their Stillsuits would also be a likely invention as you wouldn't want to waste sweat or urine because of the water content. Of bigger concern would be the impact on vegetation, both marine and land based. The real issue here is that trees (which you'll still need to generate oxygen, especially now the phytoplankton is gone) need lots of water to grow, and they expect to live in an environment where they regularly get rainfall. You've also got the food issue as crops need water. Meat is definitely out because you won't have enough water for grass, and the amount of water required to 'raise' a meal of red meat by comparison to a vegetable based meal is massive. Even with 10% of the previous water levels, I don't see you rebuilding large cities of any kind because the amount of water required in most mining and industrial applications is prohibitive and the infrastructure required to do so requires seeding from an industrial complex probably from before the water loss. I'd see society degenerating into small clans, fiercely protecting what water holdings and crops they have the manpower to defend. Clan structures don't scale well, the lack of water also makes trade next to impossible because of the increased cost of 'shipping' and as such, societies won't reach the critical mass of size where there is sufficient food and protection in place to support a small core of researchers or scientists tasked with making things better. [Answer] Life would probably revert to some basic form. A large part of the phylogenic tree would disappear. Bacterias, archeas, micro organisms and insects would probably survive. Anything sophisticated like mamals would have a hard time and humans would probably disappear. [Answer] If your goal is primarily water shortage, would it work if the water isn't actually gone, but has somehow become non-potable? It would need to be some means which would make reclaiming usable water either impossible or difficult to the point of being almost prohibitively expensive, so both water and the means to obtain it become precious. Some form of toxicity could also contribute towards desertification. Not sure how you accomplish this. It's been years since I read it, but I've a vague memory of Gregory Benford's *Timescape* featuring some form of algal contamination that led to an ecosystem collapse. A lesser form of that might provide you with a lack of usable water without the issues associated with actually removing it. And you could still use it for industrial purposes which would resolve the issue @Tim B II raised, ]
[Question] [ Can rings be used as a monetary system? Are there any flaws? I took inspiration from Celtic ring money, rings made from different metals- the value of a ring depended on the material it was made out of. E.G. A copper ring would cost less than a silver ring, and that would cost less than a golden ring etc. People would wear these on fingers. I think there might be problems with thievery etc. Any ideas on how to make it better or express any flaws? [Answer] Traditionally Japanese coins had holes through the middle and could be strung together for ease of transportation: Japanese coins courtesy of Wikipedia <https://i.stack.imgur.com/06CoU.jpg> In the Dune series the Fremen would use rings as currency backed by water, these weren't worn on fingers but in their hair so another take on stringing them. So it's not an uncommon idea, however it's probably not a good idea to wear them on fingers as people have different finger sizes so often the rings wouldn't fit and you have a maximum finger capacity for rings, it would also be difficult to hold things if your fingers are covered in rings. Imagine bandits attack you and your fingers are unable to bend due to being covered in rings so you can't grab your sword. I imagine in such a world people would end up stringing the rings together anyway. [Answer] Anything can be used as money, as long as the society using it agrees that it has value, or represents value, in a consistent manner. For some examples, see <https://tvtropes.org/pmwiki/pmwiki.php/Main/WeirdCurrency> - specifically, the last section, with "Real World" examples. Chinese coins at one time were square-pierced disks; this is the origin of the square-pierced tokens in modern mah-jongg sets, and also ultimately led to the symbols on the "dot" and "bamboo" suits in the game; the dot was originally a single coin, and the "bamboo" stick was actually a string of 100 coins. [Answer] Not an easy system. Coins can be minted with basic technology. Rings can be easily made too, but putting any distinguishing marks on a ring is technologically more difficult ([Signet rings](https://en.wikipedia.org/wiki/Seal_(emblem)#Signet_rings)). You can have plain rings, but then anyone can make rings, and they would no longer have a face value. Engraving would work for high value rings, the ones that worth more than their weight in gold. P.S. This answer assumes that the ring must be wearable and not just a "topological ring" like pierced coin. [Answer] Besides real-life cultures, the videogame Tyranny uses rings as currency: <https://tyranny.gamepedia.com/Rings> These rings aren't really coins, but more like loops of metal. They also aren't worn on fingers, but on strings, ropes, or leather cords tied around the waist or neck. In fact, as stated in the linked wiki article: "As rings are used as currency, it is considered vulgar to wear rings as adornment or jewelry. Such decorations are seen as vulgar, and those who wear them are held in contempt." Of course, you're free to invent whatever customs you like. Threading rings with cords or tying them with ropes makes for easier transport (and would allow individuals to carry more than 18 rings (assuming 2 per finger and 1 per thumb) at a time. If what you're looking for is more like coins with holes, you might still tie them together with cord or string, for ease of use. Specific stacks of rings might be a standard lump sum. For example, a string holding 10 copper rings might be the in-universe equivalent of a €5,- bill. That might lead to slang terms for specific amounts of money. Think of people referring to 1 dollar as a 'buck' in reference to deers, which were hunted so much that a deer hide at one point only cost 1 dollar. Hence, a buck. Or I've heard people refer to 100 dollar bills as Franklins, in reference to the guy depicted on the bill. Of course, you can always carry rings in a purse or bag instead. That might be less vulnerable to theft, depending on the construction of the bag and cords under consideration. [Answer] Not a new concept. Coins have been struck with holes in the middle to reduce their value <https://c8.alamy.com/comp/EJX2RP/a-string-of-ancient-coins-EJX2RP.jpg> <https://i.pinimg.com/236x/e3/77/dd/e377dde3f7fa5d76f54b4ce11395dc1e--chinese-style-feng-shui.jpg> <https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSmbZjeAM58oWw3aP-edjUU1RM-UNf2fd3H_TpXC66N8kIt-CBJAw> Wearing them as rings is a problem as it both limits mobility and the amount of money you can carry [Answer] Well people have made money out of rocks he or she with the largest rock or boulder was the richest one in town sooooo you could do it by ring color, weight, or start adding in gemstones or rocks set into the rings. Rings could be carried not on the finger but around the neck for high shoppers. For low shoppers hands, wrists, or up on the bicep. The old fashion pouch would also work if you are allowed to employ pins for which to string the rings upon. Rings could be so tiny not even a baby could wear it or so large they become collars that fit over the entire skull. Looping them on guard dog's necks who are trained to never leave their owner is one way having a tiered sorting box is another small enough (depending on the status and wealth of the owner) would slip in and out the ring sizes arranged by the person so they have what they need. Yes theft would be a possibility like any society so securing it on ones self or at home is also priority would they hide the rigs in false drawers say under the mantle shelf? Or inside a sock tucked into their shoe? Thieves would have to look longer and in more places to find the tiny loot but big large hoops no problem but that is a problem porting it about what if you get the grand daddy of all rings that is bigger then the door? Made just so the owner could say how rich they were? Fools metal work could be common too left out for thieves to steal. Maybe a test is required before any transaction is complete to secure the metal used. A device, magic, harmonics,biting could all work but what about the morron with a million rings who comes in and crashes the economy? Or only the king/queen may have the largest hoops in the kingdom cuz they say so or will kill you. Remember the society I told you about with rocks ROCKS? Yeah those things were everywhere when too many people got too many boulders they eventually switched the currency to....seashells... yeah...so rings can be fine or coins with holes in them too just if its a common item and isolation is why they do it until something else comes along to replace it just think of the issues with normal coins. [Answer] Chains You could make chains out of precious metals. You could just break or if gold bend open a link of the chains at different places to fraction out money, the chains could be worn as belts to help make them secure or even many chains off a belt making a kind of chain skirt. Of course this relies on precious metals valued by weight instead of any standardized currency. Standardizing rings is tricky (proving they are standardized is even harder) and you will occasionally generate some broken rings. ]
[Question] [ I'm trying to create a world where there's an equator-like divide running along the axis(?) of the planet and the two hemispheres are perpetually different in terms of temperature. Basically, I want one side of the world to always be warmer than the other side and for the temperature change to be noticeable when crossing over an invisible "divide". I'm not a physicist and I know very little about astronomy so my thoughts on this might be completely off track, but I was thinking that maybe a circumbinary planet with two stars of differing heat intensities might work? But I think that would affect the changing seasons more so than the relative temperatures of the hemispheres, is that right? From what I've read, the angle of the planet in relation to the sun is what causes the difference in global temperature, but I don't think that wouldn't create the drastic change that I'm looking for. Any thoughts on how I could make this work? [Answer] Tidal locking is a fine method. Here is a different method. **Asymmetric magmatic heating.** [![mars being hit](https://i.stack.imgur.com/Mfskr.jpg)](https://i.stack.imgur.com/Mfskr.jpg) <https://www.reuters.com/article/us-mars-crater/giant-crater-explains-strange-shape-of-mars-idUSN2530000020080626> Your world was hit by a large impactor. On resolidifying, the iron core of the planet was no longer in the center of mass. A large lobe of silicaeous material overlays one hemisphere and what was once the metal core is displaced, to the opposite hemisphere. The metal core conducts heat, and also provides substrate for eddy currents and ohmic heating. The hot metal core is close to the surface in that hemisphere. The entire hemisphere has a situation much like Iceland with ample geothermal heat. This is the hot side. The far site is insulated from the core by the overlying light materials and has essentially no geothermal activity. It is warmed minimally from the core and only by the sun, which is distant and dim. This is the cold side. [Answer] Take a planet like Mercury, with no atmosphere, and have it tidally locked with the central star. When you cross the terminator (the line dividing the day region from the night region) you quickly go from "scorching hot" to "hell has frozen cold". The lack of atmosphere will take care that no diffusion of heat takes place. [Answer] **TL;DR** It can be done, but there would be huge storms as a result. **Long explanation** The only natural phenomena that I can think about that would be able to produce this sort of result would be [tidal locking](https://en.wikipedia.org/wiki/Tidal_locking). Basically what happens is that a planet is so close to its star that the gravity makes it spin at the same rate it orbits the star, making one face of the planet permanently fixed to the star. From the planet's perspective, it would be like a sun that never moves. Now, this has its complications, mainly the following: 1.- Having a tidal lock on a star like our sun would melt half of the planet so in order to be habitable the star would have to be a red dwarf: in other words, a very small and cold star. 2.- Even with a small star the temperature would be really high on the bright side. Just to put in perspective, the sun for such a planet would occupy probably at least half of the sky; on the equator, temperatures would be enough to melt rock. Probably the habitable part would be on the twilight between the dark side and the bright side. 3.- But talking of the dark side, it would be incredibly cold, freezing solid oxygen kind of cold due to its permanent shadow if it weren't due to the next point. 4.- You have atmosphere, and storms within atmospheres are driven mainly due to heat differences. When air is hot, it expands; when it's cold, it contracts; and when a cold mass of air crashes with a hotter mass of air, they start to combine, expanding and contracting respectively creating something called [eddie currents](https://en.wikipedia.org/wiki/Eddy_current), which are common to what we call a tornado. On Earth, this happens when the sun heats the sea and its hot air crashes with the cold air coming from the poles, and the greater the difference the greater the force of the storm. Now on your world we are not talking just about a small gradient like here on Earth. We are talking about air as hot as melting rock crashing with air cold enough to freeze oxygen; there would be global storms stupendously huge engulfing the planet all the time, making the dark side somewhat warmer and the bright side somewhat colder than they would be otherwise, but the air speeds would be just amazing, probably in the hundreds of mph. Actually there are [some scientific studies on this](http://www.pnas.org/content/111/2/629). [Answer] The Earth's seasons are caused by the axial tilt of the planet. In June, the Northern hemisphere is tilted 21 degrees toward the sun, the Southern hemisphere is tilted 21 degrees away from the sun. This means the Northern hemisphere will get more and more direct sunlight, which makes it heat up. Over the course of ~25,000 years, Earth's axis precesses; the North pole points at different places in the sky. This is caused by tidal forces between the Earth, Moon, and Sun. It should be possible in a more complex solar system for this precession to happen much faster, such that the axis precesses at the same rate that the planet orbits the sun. This would lead to one hemisphere always being tilted toward the sun, and one always tilted away; a summer hemisphere and a winter hemisphere. Unlike a truly tidally locked planet, both hemispheres will have a day-night cycle. The summer hemisphere will have longer days, the winter hemisphere will have longer nights. Depending on the elevation, there may be peaks of eternal daylight at the summer pole, or valleys of eternal night at the winter pole. The tidal forces necessary to make the precession happen this quickly would lead to some extreme tides; perhaps hundreds of meters or more. The unbalanced heating would also lead to some pretty extreme weather, especially near the equator. ]
[Question] [ Why might a species advanced enough to develop genetic engineering start a process by which their own genes, over hundreds of years, would get edited back to resemble their more primitive ancestors? For example, why might humans in the year 2200 release a gene-drive, germ-line retrovirus that reverted humans to Australopithecus? [Answer] To display wealth. Like the peacock's tail, expensive displays are indicators of health and wealth. Think of the expensive shoes, suits, outfits, watches, jewelry, and cars that wealthy people display. It's conspicuous consumption. Or the silly, colorful hats and outfits of the rich in Hunger Games. If someone, say, from a rich family, were engineered to have 'harmful' or 'ancient' traits that made them clearly distinct from the riff-raff, that would be an obvious sign that they were so wealthy they could afford to sport such traits. It would impress business and social partners. Although not genetic, there is some thought that [head-binding](https://en.wikipedia.org/wiki/Artificial_cranial_deformation) was practiced to make different castes of people visibly distinct in society, e.g. the nobility have taller, oval heads. In order to shape the skull like this, you have to wrap the baby's head basically from birth, so it's a reliable signal. Think of Chinese foot binding, Victorian corsets, or the [elongated necks of the Kayan](https://en.wikipedia.org/wiki/Kayan_people_%28Myanmar%29). These are slightly harmful to the activities of daily life, but thought to increase the beauty and desirability of women in those cultures. If someone were genetically engineered from birth, that's something you can't fake or lose. And as a germ-line trait, it would be passed to all their offspring. [Answer] There could be desirable traits that are wanted. For instance, many with European ancestors have Neanderthal DNA. Neanderthals were believed to have been bigger and stronger, though possibly not as smart as homo sapiens. By editing the DNA to emphasize the size, strength, skeleton and musculature of Neanderthals (while keeping the brain) you could make people who are better adapted to living in heavy G worlds, or better at labor and opening pickle jars. Australopithecus were smaller than homo sapiens, but with musculature like an ape, and so might do well in areas where space is limited, such as tunnels, where we'd be living for quite a while while colonizing Mars. [Answer] To create an easier to manage slave class. *(You didn't say that everyone had to devolve!)* [Answer] A genetic weapon(virus) has been released on planet earth that targets a DNA sequence that is recently new. Animals and vegetation can carry the virus but it is inert and only effects us. The virus prevents people from having more than one child if any. Humanity will become extinct over the span of several generations. Our only hope lies in removing that DNA sequence from our DNA. Removing it outright fails and the only option left is to revert to a stable DNA without the DNA sequence that the virus targets. [Answer] # Climate change Let's say that a species lives in a world that used to be temperature. Over time, though, greenhouse gases were released from deposits in the soil, thus increasing the temperature of the planet slowly. Over millions of years, the species evolved to better survive in these warmer conditions (for example, by getting rid of fur). Now, when they have developed this genetic engineering, an asteroid hits. Suddenly, temperatures drop substantially, bringing the climate back towards where it was originally. The species doesn't have the technology to adapt to this using machines - but they can "devolve" back to having fur or other characteristics they had gotten rid of when temperatures rose. I don't know the details of the members of the genus *Australopithecus*, but I do know that given that they dwelt in Africa, they were most likely suited for hotter climates than many humans are today. So perhaps we should use the reverse of my example - a case where it suddenly gets much hotter, not much colder. [Answer] To ease and make safer childbirth. Modern humans evolved smaller birth canals as a consequence of walking completely upright. Earlier ancestors weren't as upright as we are today, and therefore could have larger hips and birth canals. This made childbirth more dangerous for modern humans. If women were engineered to have larger birth canals, ala our ancestors, this would make childbirth safer for both the mother and the infant. [Answer] In Star Control 3 game (which was made by different studio and was so unlike Star Control 2 that many fans refuse to acknowledge its existence, but that's irrelevant) Precursors are revealed to combine genetic memory with sapience-removing de-evolution to hide from cosmic horror which periodically visits the galaxy, eats all the sentient species and seeds new sentient life. Note: SC series in not a Mass Effect ripoff, if there is direct relation, it's other way around: SC2 is pretty much a ME done 15 years earlier. Reasons that aren't a direct inspiration might be: * Australopithecus become unduly glorified (just like terrible times long gone are glorified because most people only look at glamorous slices of those times: almost everyone wants to be a medieval king, but if those times came back almost everyone would be a medieval peasant) because of in-touch-with-nature-something or other nonsense and people want to become like them. * Some group of people volunteers themselves and their offspring (heavily violating modern ethics) for sake of recreation of extinct species. * Instead of recreating our main ancestors they are trying to recreate Homo neanderthalensis whom Homo sapiens sapiens did briefly interbreed with, before driving them extinct. A little bit of neanderthal genome is present in modern humans. * Maybe Australopithecus had some adaptation which are going to be important? Incoming [hot age perhaps](https://en.wikipedia.org/wiki/Geologic_temperature_record)? [Answer] > > For example, why might humans in the year 2200 release a gene-drive, germ-line retrovirus that reverted humans to Australopithecus? > > > It's the Greens. Not all of them, but a lunatic offshoot. Think Ted Kaczynski with a genetic engineering degree. In order to get humans to abandon the technology that is destroying the planet (this Ted's words, not mine), he reverts everyone to a more primitive version. Australopithecus were apparently about as intelligent as a chimpanzee. While they might be able to operate some technology, they would not be able to maintain it. Over time, the power plants would stop producing electricity and virtually all technology would cease to function. It is of course up to you how successful he is. Perhaps the retrovirus is eradicated before it does much damage. Perhaps it reverts everyone. [Answer] For finding "[Adam](https://en.wikipedia.org/wiki/Adam)" and discredit popular religions. Different de-evolution stages could also provide historical information about Earth (museums with highly priced tickets could have a live de-evolution show). DNA sequences found in old human remains could also be compared in order to validate and understand why certain "evolution" occurred. If the Earth does not exist in the year 2200, by feeding rescued living beings samples to the "de-evolution machine" will allow to map and recreate a similar planet from scratch. [Answer] I don't think it would happen.. for humans to evolve Backwards... it would mean that those possessing the genetics to 'revert' would need to breed... humans as a species are very picky on who they will and wont breed with. if someone was to bear the traits of an early humanoid I don't think there would be a long line of people wanting to procreate? therefore the Genes would not be passed onto the next generation. I'm not saying We humans don't like to procreate with those that have 'faulty' genes or such but I don't think many would be willing to procreate with a person resembling an early humanoid? It could happen with other Species if there are those resembling earlier species traits it could happen. Some species of fish for example have lost their eyesight by being Cave dwelling with very little to no light. Eyes were not there at the very early stages of life so they have technically reverted back to an early genetic variation where Eyes were not in the Genetic make up. [Answer] This could happen to a population which was artificially isolated into a small region, to which it evolved to. If that isolation were to be ended, and that species finds everything it had adapted to was wiped out, the shortest path to survival could be to go back and try again. This almost never happens in natural evolution, because nature prefers not to be wasteful. It'd find a use for those genes rather than just tossing them away. However, your question is of an advanced species which can do genetic engineering. Such a species is more likely than nature to make a decision to take their genes down a specific path, only to find that they had misanalyzed the situation, and these new genes were a complete evolutionary dead end. For example, you might devise genes which appear to adapt faster, using Turing machine style discrete thinking, only to find that these new genes always enter a loop, unable to evolve against the ever evolving environment. In such a situation, a species may throw their hands up and say "nature knew best," and toss out all their hard work. They would likely try to adapt their new genes to break through the hurdle, but that may be impossible due to time constraints or mathematical limitations. [Answer] Hmm.. excellent question. When I first read it, it occurred to me that, after the population wars from the exponential growth of humanity, and genetic tampering of both food and population, it was discovered that, at some point in the evolution of humanity after gaining sentience, a flaw appeared in the genetic makeup common to all humans. This flaw was in genes so integral, and so wide-spread, that even gene therapy could not repair the damage without the likelihood of irreparably damaging the DNA. Without knowing it humanity had tailored a series of events that would lead to the death of 99.999% of the population within a year of the first death. It would then be the only chance for humanity for them to wake dormant genes and essentially reset the human genome, hoping to give them a chance to avoid the genetic breakdown.. plus, this time the humans evolving wouldn't have oil or coal to abuse. But truth told.. I have to think the most likely reason would be vanity. Right now we look at people from the 80s and wonder what the hell could make them think that hair was ok. But to them it was.. by the time humanity has discovered a million new vices, it would probably be in style to look like a neanderthal, since everyone else would be custom tailored to look.. "perfect" ]
[Question] [ If we had Full-Body Immersion MMORPGs, how would morale-boosting and morale-lowering skills work for players? By that, I mean, how would the game forcibly make players more or less confident, even if their out-of-game personality would not fit their avatar's confidence level? Like a coward playing that game, and is always cowardly in combat, flinchy, a weak hitter, defeatist, etc... But that's just because he isn't using his knowledge and physical ability to its full potential... Then, on application of a Bravery Spell, he uses his full potential as a confident person. --- **Actual Question** If it is possible, what game mechanics can I employ to tailor a player's confidence level? While sticking to these criteria: 1. Having the smallest amount of additional technology other than a VR headset like a [SAO Amusphere](http://swordartonline.wikia.com/wiki/AmuSphere) 2. You only can control external stimuli (no drugging) 3. No forcibly taking control of his character in any way, no nudges... But, you could move the monsters? [Answer] In games I know that have morale effects, the bonus/penalty is just a numerical modifier to an existing number. I see no reason why this would change for virtual reality. Suppose a player receives a +30% boost to their jumping ability. While so affected, apply a 1.3 force multiplier when the player performs the jumping action. So instead of jumping 1 in-game meter, the player jumps 1.3 in-game meters. Suppose a player receives a -25% penalty to their attacking ability. While so affected, apply a 0.75 speed multiplier when the player performs the attack action. This slows the character down and gives opponents a better opportunity to evade. These examples only apply to in-game, forced events, such as a wizard casting a spell on the player or the supernatural aura of a fearsome monster. To physically (psychologically?) make the player more confident, you would need to supply some form of in-game cues, such as a noticeable limp in a monster's gait or a clear opening in a warrior's defense. The inverse would apply for less confidence: the monster has already demonstrated feats far beyond the player's (character's) skills or the warrior is surrounded by corpses and shows no signs of fatigue or harm. [Answer] **Music, Vision Filtering, Conditioning** How about a combination of music, color filtering and [conditioning](https://en.wikipedia.org/wiki/Classical_conditioning)? During the tutorial to the game, you could have the user practice different things they'll need to do in the game. Then, when they fail, or during parts where they're likely to fail, play the 'not confident' music. This will make people associate that music with parts where they're likely to mess up. You could also tint their vision to be subtly blurry with a color tint to strengthen the effect. Then, when you want to make them feel like they will mess up, you tint their vision and play the music. As far as them feeling more confident, you could also have parts of the tutorial that seem really difficult, but are actually easy (or the game makes them hard at first, and then easier). When the user accomplishes this seemingly hard task, they'll feel like they're pretty great at the game. Then you'd play your 'confidence' music and tint their vision to be super clear and use a slightly brighter color palette so they feel more confident. I think this all works best if the user doesn't understand what you're trying to do. In a lot of games they'll tint the screen red and play heartbeat sounds to let you know you're about to die. I usually feel urgency/adrenaline when this happens to me (and I'm really into the game). I think the same could work for confidence. Movies use music and color palettes to set people's mood throughout the movie. [Answer] Confidence is tied to performance, so controlling a player's performance will give you control over their confidence. When a player feels their performance decreasing, they tend to naturally become more cautious. You can control their performance by limiting their senses. Shorter view distance, blurred vision, sluggish controls, muffled sound effects, and inaccurate readings on meters and other UI elements all reduce performance naturally. Some restraint is necessary here, as too much impairment makes a game frustrating and can drive players away. But a little bit can be quite impactful. You can also control performance by adjusting rewards and losses: greater rewards increase bravery, while greater losses increase caution. For example, when a player's character normally regenerates lost health, the loss of that regeneration will make the player more cautious. Similarly, if the player gains the ability to regain lost health by attacking enemies, then the player will become braver and enter battle more often in order to regain lost health. Confidence in performance relies on the player's ability to assess their performance and compare it to the challenges presented by their environment. If a player is very powerful, but doesn't know it, and is confronted by an enemy which looks menacing but is actually weak, the player will be cautious until they realize through trial and error that their power is greater. The inverse is also possible: a deceptively weak-looking enemy could be more powerful than the player, overinflating player confidence leading them to attack it head-on. You can bypass the need for trial and error by providing UI elements to indicate differences in power, e.g. marking enemies which are too powerful with a red skull, or automatically targeting the weakest enemy for the next attack. Confidence is also closely correlated with a player's sense of isolation and loneliness: a player in a group is more confident than one who is all alone in enemy territory. Your game doesn't need to be multiplayer either - the player's allies could be AI-controlled and the effect would be the same. Player confidence also depends on their understanding of their surroundings. Therefore if you want to reduce confidence, you can simply overwhelm the player with information, e.g. by generating more enemies or changing the shape of the terrain. The more things change, the more the player needs to keep track of, and the easier it is for them to become overwhelmed and feel the need to retreat to a more controllable position. [Answer] Depending on bravery level, the computer could implement more monsters. Not *real* mosters, but illusions. At full bravery level, you know exactly which monster is real and needs to be attacked and defended against and which is fake and can be ignored. You are confident in your abilities. At full cowardice, the room is full of monsters and you don't know which ones are real, which means you have to be defensive and treat every single one as a real threat. If illusions do not fit the world, you could use other information, maybe their threat level, or which weapons they have. The point is that enough information makes people confident, while too little information makes them doubt their actions. [Answer] **Audio**. While incidental music and conditional heartbeat tones can be a good indicator to the player, it can also serve to prepare the player for a section, potentially bolstering their confidence during sections where they should not be confident. To make a character **less** confident, the audio track should be similar to the normal audio track, but **more randomized audio** during situations where confidence would come into play, with slightly more discordant/offbeat tones being played than normal, and [hits](https://en.wikipedia.org/wiki/Orchestra_hit) or [stabs](https://en.wikipedia.org/wiki/Stab_(music)) at random intervals where it might cause the player to slip up or fail a task that requires concentration. For more relaxed or confident sections, you can play soothing music or nature sounds. You could also look into the effects of audio types that have been used in for [Brainwave Entrainment](https://en.wikipedia.org/wiki/Brainwave_entrainment). You could modulate the music or audio track to employ low frequency or low volume [Binaural beats](https://en.wikipedia.org/wiki/Binaural_beats), [Monaural beats](https://en.wikipedia.org/wiki/Monaural_beats), or [Isochronic tones](https://en.wikipedia.org/wiki/Isochronic_tones), which have been implied to have various effects on the listener's state of mind. It would also be useful if not completely necessary to utilize [Neurofeedback](https://en.wikipedia.org/wiki/Neurofeedback) in the VR tech in order to monitor the user's state of mind, and adjust the audio accordingly for the intended effect. *Conversely*, in order to make a character **more** confident, Incidental music and nature sounds would be great, but I feel it is not enough. A character may still run away from anything that would appear to be too threatening. So while I disagree with altering the player's vision or statistics in ways that essentially break the game or make it seem unreliable (and thus unplayable), there's nothing telling me that you can't **outright LIE to the player**. Make hostile creatures seem more docile to a player whose confidence is boosted. Make their models smaller, perhaps. Make them appear to have fewer hit points or be already wounded (which would translate to other players as the confident player performing more critical strikes, or missing less often than normal). [Answer] The typical MMORPG involves assigning numeric bonuses to activities, such as swinging a sword or casting a spell. If you are in a VR world where one cannot simply assume the numbers are sufficient, then the story gets more complicated. I would consider a MMORPG with some concept of a guardian angel that helps you. Perhaps they help you as a level 1 character, so you can more rapidly adjust to the game, but vanish over time. This guardian angel would help you make your desires happen. If they believe you wanted to jump over a ravine, but ever so slightly missed, they might tweak the gravity constants locally to accomplish the goal. A confidence boosting ability would bring back this assistance. If players were made aware that this effect was taking place, the players themselves would naturally become more confident as well. [Answer] Back in the dark ages, when such games were played with paper and dice, I often encountered situations where a player was acting "out of character". A timid player might have a hard time running a courageous character, or vice-versa. Correcting such situations really only requires informing the player of what they are doing wrong. I usually kept a pack of index cards with helpful advice like "You are being to timid". Passing such a card, face down, to a player at an appropriate moment would make the aware of the issue and almost always, they would immediately adjust their actions. I don't think you need to trick or game your players into playing their roles. You just need to let them know. [Answer] I don't think there is any way to *guarantee* that the player will be more confident. Thus, I see two ways of approaching this: 1. Accept that you cannot force confidence on someone and simply put systems in place that *encourage* confidence. This means that players lacking confidence may often have a more difficult time in the game (just as they might in real life). 2. Ignore the literal meaning of improving a character's morale/confidence in terms of emotion, and instead cut through to the base-level change to the character those types of spells/effects produce in other games. On point #1, assuming all enemies are given some sort of danger ranking/threat level, that stat would just need to be treated as a *perceived* threat level rather than an *absolute* one. This level would be inversely related to the player's confidence. An interesting side effect of this is that overconfidence becomes a real risk. If a player is too confident, the perceived threat level may be so low that they don't take a threat seriously enough and get themselves into trouble. Other answers have hinted at other ways to encourage players to be more confident such as causing the monster to appear injured or displaying additional monsters that are merely illusions, etc. If the game being played in single player only, those could work, but if there is any interaction with other players (especially cooperative), various issues come up with players seeing monsters too differently or the confidence of other players ruining a separate players fight (imagine if you were doing just fine against a very injured monster, and someone with extremely low confidence enters the room; suddenly, that nearly-dead monster is at peak condition and 5 feet taller—not good). **Edit:** From discussion in comments, simply allowing two players to see the same monster in different states would probably be fine, as long as you don't allow those states to be too wildly different (e.g., one player seeing a monster as an amputee while another sees 8 arms brandishing large weapons). Also, potential collusion between players to get around confidence deficiencies could be mitigated by allowing overconfidence to be an issue, since that should lower the value of that type of meta-gaming cooperation. Concerning point #2, I'd postulate that in most games morale/confidence boosts to characters simply translate to increased attack (as in [Final Fantasy](http://finalfantasy.wikia.com/wiki/Bravery_(Status))) or health/defensive stats (like in [Everquest](http://everquest.allakhazam.com/db/spell.html?spell=244)). Thus, rather than trying to physiologically produce *actual* confidence or bravery in a character, you could just up their stats and trust that that would likely inspire actual confidence as well, since it would make their fights easier. [Answer] Some ideas come to mind, mostly involving visual distortions. For example, lack of confidence could introduce more jitter or sway into the player's view (especially while moving), make walkways seem narrower, make monsters seem bigger/scarier (glowing eyes, vague shadowy wisps, bigger teeth, more surprising/vicious attack animations), and so forth, while added confidence would have the opposite effects. Anyone with anxiety disorder would also "appreciate" the effect of introducing tunnel vision and a subtle dimming of the environment, as well as making the player's vision momentarily blurrier. You could also subtly introduce the sound of the PC's heartbeat and breath, and ramp up its intensity and perhaps even rate. I remember that having a profound effect on me in a horrible reality/game show in the early 2000s, and it became pretty clear that's exactly what the game producers were going for. ]
[Question] [ What kinds of techniques or mechanisms, fantastic, magical or scientific, would make it so that an attacking army would take far less losses storming a castle/walled city than it would by standing outside of it and attacking it with siege engines? A few things that come to mind would be some sort of magic bubble shield that protects against wall breaking siege engines, or maybe super powerful defensive artillery that would allow the defenders to attack and break up an attacking army if they were to simply stand about. Another thing to note is that it would be acceptable if the cities/castle have reasonably easy ways of gathering/processing food within itself, so that the starvation of the defenders would take quite some time. Besides that, another idea to toss up could be that it is naturally unsafe to be outside of a castle/city walls for prolonged periods of time, and that an attacking army would then also need to be able to deal of fierce local flora and fauna, or some other thing like the castle is suspended in the middle of the volcano, and the volcano could erupt at any time, wiping out an attacking army, but the castle is designed such to be alright against such a thing. I digress; what could be good to promote bloody storming over boring, practical, safe sieging? PS: I rather have it that in this setting, due to the presence of certain things, it is actually more costly in terms of life to siege, and that storming a castle is safer for the average soldier. [Answer] In a word, "winter". I know that extreme climate has been mentioned but if you go back in time a few hundred years, feeding a few hundred troops let alone a few thousand while stranded in the middle of no-where outside an inhospitable castle was a mean challenge. Even in Europe, it did not need to be an extreme winter to end a campaign. The oncoming winter would lead to to issues making storming the castle a make or break option. * As mentioned, lack of food. * Lack of heat. Admittedly, cutting down the local forest would do much for this but still, a pitched tent and a huge fire is no replacement for a warm, dry bed in a house or even a barracks. * Hygiene. Again, mentioned before but sanitation would be a serious issue here, probably not much in the means of medical care and should a winter disease such as influenza were to rear its head in camp such as this, the effects could be devastating * Morale. The longer the troops have to sit around in the cold and wet with little food, watching their colleagues grow sick, the greater the likelihood of some kind of rebellion, especially from any mercenaries/hired arms who are only here for the spoils. Even if no mass rebellion, desertion would also start to become apparent. A wise leader would be aware of this and would have to make the decision of whether to risk everything and storm the castle or to return home empty handed and face the embarrassment of failure. Of course, abandoning the siege would then reduce the likelihood of the troops wanting to go on another raid next campaign season not to mention swinging public opinion against the leader making this a very difficult call to make. However, the later this decision was put off, the greater the chances of casualties, not only from the aforementioned factors whilst encamped but also from further complications caused by winter's progression during the journey home. As mentioned earlier, if a particularly harsh winter were to come early then taking the castle might be the only way to survive short of surrendering to the forces inside the castle. A few other miscellaneous reasons:- * If there was a "do or die" culture then risking everything on a castle storm at the end of the campaign would make sense. A slim chance of success vs freeze/starve to death vs guaranteed public execution for a failed siege would probably encourage people to storm the castle. * A different time limit e.g. the castle is holding the pregnant queen captive. You must storm the castle to rescue the queen before she gives birth to make sure that the child is not harmed. * This is not the only castle to take on your to-do list this campaign The above are all reasons why you would have to storm the castle, even if you didn't really want to. However, there are reasons why you may want to storm the castle:- * Technology. sappers are a prime example, I believe it was during the Crusades that the Arab forces undermined a Crusader castle and rather than destroying "such a beautiful castle", instead showed the garrison leader what they had done and earned a peaceful surrender. Even without going to this extent, it would only take a few weeks to dig under one wall. Burn the supporting struts in your tunnel and the wall falls down. Now it becomes an almost equal fight as much of the defenders' advantage is lost. * Locating an entrance. While setting siege to the castle, the secret entrance the castle's food gatherer's use might have been discovered. Maybe the stream that flows out of the castle can now be waded upstream. * Knowledge. Maybe the last day of October is some local ceremony/celebration that involves everybody getting blindingly drunk at the end. What better a time to storm a castle than when most of the defenders are barely conscious? * Sickness. Possibly plague strikes inside the castle (catapulting those rotting cows inside the walls seems to have worked or was it poisoning the stream that flows into the castle). Either way, sick defenders are much easier to overcome than healthy ones making it a great time to storm the castle rather than wait for them to get better. I would conclude that there are credible political, seasonal and situation based reasons why storming a castle may be better than setting siege to one. Some may incur fewer losses but overall, if you can feed and care for your troops, a siege is generally the less likely to incur losses even if it costs the most and takes the longest. [Answer] Besieging a castle was also a risky enterprise, due to: * Diseases: think of thousands of men camping together without proper sanitation. * Risk of attack by relief forces. Even if the outside force is not enough to present battle, they may attack your foraging parties, reducing the income of supplies. This would be my favourite. For example, the crusaders of the First Crusade were in the brink of starvation when they stormed Jerusalem. Other reasons: * Some castles had a harbour. Unless the attacker had a fleet with them, besieging them would mean nothing. * Also, political considerations (avoid time to your enemy to gather allies, lack of money to pay your troops, need of a quick victory because there is unrest back home). * And additionally, it may be that your enemy has some other advantage that will vanish with time (v.g., the enemy numbers are largely untrained militia, but every day it passes they are better trained, or a section of the wall is already damaged and the defenders are repairing it). [Answer] Be careful going in this direction. It has the potential to make your story feel instantly fake. Consider why castles are created in the first place. The single solitary purpose of a castle is to give the defender a positional advantage against attackers. Against a lesser wall, it is often effective to storm the walls. Castles were designed with the expressed intent of making this difficult to do. So if we keep the abilities of a castle to fend off storming fixed, but make them harder to siege, we make them virtually invulnerable. They were extremely good at stopping stormers, and now they're even better at stopping siegers. On the other hand, if we weaken then to storming, then the question of "why'd we build this dumb wall of rock in the first place" starts to show up. There has to be another dimension to the story. Castles were designed to be an unmoving defender on the battlefield. If we want to keep castles in existence, but make them weak enough to be stormed, we're going to need a third player on the battle field. Time is one good force. One of the major issues with a siege is that it takes a lot of time. Any effect which prevents protracted engagements is effective. You suggested several effects (werewolves striking on the full moon seems particularly effective). However, you don't even need to resort to magic. Consider a world where fluid movement of troops is the norm (more like modern day combat, less like medieval combat). The construction of siege engines is an expensive endeavor. While one is doing so, ones army is no longer defending their citadels. If there were 3 parties in balance, any protracted assault would leave your own home weak to attack. On the other hand, if magic is an option, consider a castle protected by a shield like the shield generators from Dune. Dunes generators were explicitly written by Frake Herbert to take ranged weapons off the table for his story. A fast moving object was stopped, but a slow moving object is allowed through. This created an entire school of combat which sought to slowly get a knife under the shield to strike with. Scale this concept up from personal shielding to army-and-castle sized and you have a solution which refutes large ranged attacks, but allows individuals to walk through the shield slowly. All you have to do is weaken the capabilities of a stone wall, or else you'll still have a stone castle preventing a storming army. Weapons that use vibration to crack stone might be an effective way to discourage relying on massive stone structures. [Answer] There isn't really that much of a question here anymore, you've basically answered yourself straight from the get go. If the area around the castle is so dangerous that sitting around, waiting, for any amount of time would be disastrously dangerous, whether from meteorological phenomena, rabid wildlife or just environmental factors, then no one would ever even really think of sieging someone else's castle. In fact, then a new question would crop up: Why are they even attacking such a terrible place to live in the first place? Its not even a matter of storming being better than sieging. If the castle was built, for example, to keep the environment at bay rather than any potential attackers, then you can imagine that being in the castle is more than just a matter of tradition. Its a matter of safety - you would not last long without the castle, just like those blokes standing about outside your walls right now, coincidentally castle-less. [Answer] The problem here is not making it practical to storm the castle. There are plenty of ways, ranging from levitation magic to cannons with explosive shells. The problem is making it practical without rendering castles obsolete. The purpose of a castle, or any defensive fortification, is to render direct assault very costly in terms of men. In order to encourage castle-building while still permitting assaults, you need to make assault mind-bogglingly expensive: you need to hire a small army of mages to levitate the assault force, sponsor a country-wide manufacturing effort to build enough cannon shells, and so on. [Answer] The purpose of a siege is to starve out the defenders and you have already touched on a mechanism whereby a siege wouldn't be "cost effective": > > Another thing to note is that it would be acceptable if the cities/castle have reasonably easy ways of gathering/processing food within itself, so that the starvation of the defenders would take quite some time. > > > So, you could have walled cities that have most of their food production happening inside the city walls and a country side that is unable to support the attacking army then you have the motivation for storming the castle. You just have to come up with a convincing argument :) Things that spring to mind: * Marauders - bands of outlaws that attack anything short of the castle. This would explain why the food production in inside the city walls and would mean that as well as there being no farms for the attackers to feed off, they would also be a distraction and extra drain as they'd need to defend against them at the same time as trying to maintain the siege. * Volcanoes that prevent farming, but keep caverns under the castle warm enough to grow food. * Extreme climate variation. * Dragons - pretty much the same reasoning as above. Though these last two don't really fall under the tag [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") :) [Answer] **Ill start by addressing a few of your assumptions.** > > Few things that come to mind would be some sort of magic bubble shield > that protects against wall breaking siege engines, or maybe super > powerful defensive artillery that would allow the defenders to attack > and break up an attacking army if they were to simply stand about. > > > Ill address magic later but defensive artillery would still have a max range, this means that the besiegers simply have to back up a little bit farther. Admittedly it may take a few more people to maintain the siege or be easier to smuggle goods in but that isn't going to drastically change things. > > Another thing to note is that it would be acceptable if the > cities/castle have reasonably easy ways of gathering/processing food > within itself, so that the starvation of the defenders would take > quite some time. > > > Not really acceptable no. Perhaps one or two cities on the planet can afford to do this, but it should not be common. Farming takes A LOT of space. The cost to wall off farmlands would be massive, not to mention manning the walls. The best scenario to do this in my mind would be a fairly small settlement but then again a small settlement isn't going to be that hard for a large army to seize. For reference it looks like it takes about [1.2 acres to feed a person annually.](https://answers.yahoo.com/question/index?qid=1006050210699) (admittedly this is the rate for American dietary standards and could be down graded a bit) but again this is going to get more challenging as the settlement gets bigger. **So onto the main point** Tons of options here. I will break this down into science based, and fantasy based. **Lets start with science based.** * The castle is minimally defended. This can simply be its faster and less costly in the long run to storm the castle. On the other hand it may be that another army is inbound to relieve the castle defenders. * Lack of resources. This can be food or water or both. Geography plays a big role here obviously. Protracted warfare can also cause this problem. If no one has been farming for years you can't really live off of raiding the countryside. * Good ol fashioned anger. If you mustered your army on the premise that the enemy did something terrible (true or not) you may need to capitalize on that before people start to question the validity of the situation. * Off the boat. Naval invasions are dangerous in that you have nowhere to retreat. Find a weak (for whatever reason) coastal target, and seize it immediately so you have a place to fall back to in the case of a loss or tactical error. * Weakly allied forces. You brought some...friends along to the fight. But really you tend to fight each other a lot and this is a temporary alliance. Waiting around for months things are likely to get out of hand and the defenders may end up just getting a good show as the two (or more) parts of the besieging army destroy each other. I am sure I could think of many many many many more but hopefully these examples have you thinking. Simply put you need to create a scenario where the expedited capture of a location is more valuable than the extra lives lost to storming the castle versus besieging it. **On to Magic or simply the fantastic** * Magical defenses. The beauty of magic is you can do pretty much anything with it. Some common defenses are barriers, for example on gates or counter siege artillery. The full on protective bubble is an interesting idea but I find it less believable simply due to the massive amount of energy that would be needed to maintain it...plus is sort of a cheap gimmick and makes battle way less dynamic. * Spells to improve food production. Perhaps you can have your walled in farm by some combination of tiered growing areas and magical light. * Magical beasts. As you mentioned you could have the flora/fauna put up a fight against besiegers. There are few animals that will prey on humans, especially humans in large groups in the real world, but a few magical life forms and sure why not. Really when it comes to magic your imagination is the limit. I would try to avoid things that are to good to be true, or so fantastically powerful it just doesn't seem fair. The magic bubble for instance. If mages can make an entire army meaningless then whats the point of even having armies. I guess the point is, that kind of magic should be exceedingly rare if it exists at all. [Answer] In general, the only "long term" way to make storming castles practical is to develop a technology that negates the castle's defences. The high curtain walls of castles were there to prevent attackers from climbing over using the primitive siege technology of the time, and provide an advantage for the defending archers (high, protected fire positions). The Infantry Revolution starting in the mid 1400's provided weapons that allowed large bodies of relatively untrained men to take to the field on more equal terms with knights and fighting men who had trained of an entire lifetime, but blocks of pikes and crossbows don't help much in besieging or storming a castle. In our history, gunpowder weapons that could reliably breach the high curtain walls of a castle made castles obsolete, until new styles of fortifications were developed to defeat cannon fire. Vaubin forts in turn needed new technologies to overcome, and so it goes (American "Third System" forts built at great expense prior to the Civil War were systematically demolished by rifled, shell firing cannons, and the great concrete forts of World War One were smashed by superheavy high angle fire, while WWII era forts were simply bypassed (the Maginot Line) or attacked by paratroopers (Eban Emael). So while logistics or political factors may "force" your commander to consider storm vs siege, only the liberal application of "new" technology will make storming seem to be a reliable or viable option. [Answer] If it's a one-off, i.e., you need to convice one particular army to storm the walls once rather than to make it common practice across generations, then: Have a much larger enemy army incoming in a short, known amount of time. The sieger's best hope is to capture the castle sooner, and without great damage, and use it for defence. [Answer] The main reason for making a siege impractical is pretty prosaic. Logistics. An army contains a lot of men and horses. These need to be fed. A lot. A decent sized army is about the same scale as one of the larger cities in the realm, and it moves around. Your supply men will have to find supplies, and wagons to carry them, and extra food and fodder to feed the men and horses pulling the wagons to boot. Then you have to continue doing this every day as long as the siege lasts. For all but the most organized societies, this just is impossible to accomplish. So it is assault, or give up and go away. ]
[Question] [ Apologies if I sound like a madman ahead of time. Me and a friend have been worldbuilding this alternate timeline for awhile now, and I've recently become interested in the idea of one of the factions in this world performing large desert greening projects in the Sahara and Australian outback. We were thinking that the Libyan aquifers could potentially be pumped to the surface to create an inland sea in on of the Saharan depressions or even to expand Lake Chad. I'm also curious if the Nile, Congo or Niger rivers would play a part in this. My main concerns with greening the Sahara are the potential negative effects to the Amazon rainforest, the African monsoon cycle and Earths albedo. I'd love to hear every idea/potential project, no matter how expensive it may be. I do want to note, that this alt-timelines politics are vastly different from real life. [Answer] ## Slowly If you simply dump a load of water into a pond in the middle of a desert it will simply evaporate. The project you need to look into is the [Great Green Wall](https://thegreatgreenwall.org/about-great-green-wall), the general principle being to plant a forest across the width of Africa to stop the expansion of, and partially push back the Sahara. Once you start going into the details you realise that there is no fast solution to this, no magic waving of large quantities of water. You have to work on the climate, you have to build something that will sustain itself, fundamentally improve the soil and let nature build on it. The joy of this project is the massive level of international cooperation behind it, along with local support and involvement. It looks like something that will work. [Answer] ## Plant weeds There are a lot of project plans for the conversion of desert zones into grassland. The trick to them isn't water or trees. It's grass. You need something to hold the soil down for long enough for an ecosystem to dig in. In the American plains, we have an entire class of plant that is well adapted to this purpose. They root fast, grow quickly, and spread their seeds prolifically. These plants are colloquially called "weeds." No, not weed. Jimson weed, dandelion, thistle, tanglevine, and [many more](https://wssa.net/wssa/weed/weed-identification/). They move in and take over an area that would otherwise turn to dust before the grass and trees could get a foothold. A lot of people hear this argument and ask, "why would I want weeds?" If that's you, then you're thinking backwards. You don't want weeds. The soil and the bugs want weeds. The American Dust Bowl demonstrated what happens when you pull up the existing plants and plant just what you want. If you want plants to grow, you need an ecosystem, which means biodiversity. You seed an area with weeds, then populate it with animals and bugs that will eat the weeds. Once the weeds have properly tacked down the topsoil, you introduce plants with longer life cycles. The grass, trees, and bushes have competitive advantages that will make them outcompete the weeds in the long term, turning a weedy lot into a grassland or forest. [Answer] ## An iteration of the 'Sahara Sea Project'. The basic idea was and is that large depressions in the Sahara could be flooded using sea water channeled through canals usually from the Mediterranean but the Atlantic has also been suggested. The most likely target for such a project is the *Qattara Depression* which has a average depth of about 60 meters and an area of almost 20,000 square kilometers albeit it does not automatically follow that the entire basin would or could be flooded. If the project was supported by Egypt result would be a large permanent inland salt water 'sea' that could cool the local climate dramatically depending on evaporation rates and wind direction. Solar powered desalination projects around the shores of the lake could also support large scale agriculture and forestry projects around its shores that would further reinforce localized cooling effects and raise atmospheric moisture levels further. The completion of the Qattara sea project would not in and of itself change the climate enough to 'green' all of the Sahara but could in theory have an impact on a large portion of it. Other, smaller 'sea' projects could also be constructed further east but using only these projects while you'd probably end up greening a lot of the region you would still not 'green' all of it. (There's a Wikipedia Post on the Saharan Sea if you want more details on the topic.) [Answer] Diverting a bunch of water to deserts might help but before we start hauling tons of water about how about we look to the past when much of our current deserts were greener for inspiration. The big difference I'm aware of between then and now is more CO2 in the atmosphere. Which makes sense.. as more CO2 stimulates more plant growth, just ask any comercial grower that uses greenhouses, pumping CO2 in to encourage growth is a thing that's done. It also causes the pores plants use to take up gasses for photosynthesis to constrict, or perhaps remain open less often? .. either way the side effect of that is less water lost to evaporation which allows plants to survive and thrive in hotter dryer conditions than otherwise. So increase the CO2 content of the atmosphere might seem like one way to go? [Maybe not just that, but it should definitely help as part of a range of measures] Burning coal and oil to pump all the old CO2 (that was previously taken out of the atmosphere by plants to make all that coal and oil) back into it until we have CO2 levels back to where they were back when our deserts were on average greener would seem the simplest way to go about it. I can't see a direct negative effect on the Amazon from that, after all, it was around and doing just fine when the CO2 was higher and the deserts greener (or smaller if you prefer) last time wasn't it? [Answer] **You can't drain an aquifer without consequences** There are locations throughout the world today where people are suffering from declining access to water because aquifers are drained faster than they can recharge. The idea of greening the Sahara by, effectively, draining an aquifer might result in a green Sahara... but it will create deserts elsewhere. The truth is that if we account only for current technology, each and every attempt to radically redistribute a water source has resulted in bad things. Take, for example, the [Aral Sea](https://en.wikipedia.org/wiki/Aral_Sea). Formerly the fourth largest lake in the world and once the breadbasket for a region with a strong economy that included everything from food to recreation, the Soviets diverted almost all of the water from its sources to irrigate (aka, "green") Uzbekistan. The irrigation project succeeded! But it drained the lake to about 10% of its former glory and caused all kinds of problems with toxic salinity. **A Worldbuilding Solution** There is plenty of water to do everything humanity can imagine... if you can just get the salt out of it and transport it efficiently. The end result might be a much cloudier planet... which means less sunlight on the ground... which might actually kill everything (that's be just our luck...). But let's ignore all that. *Invention of the day!* I propose a practical fission/fusion/antimatter/whatever power plant big enough to provide energy for disintegration-level recycling and in need of a ferocious amount of water to keep it both cool and under control. Sea water... and a honking lot of it... is brought in to cool the system. The process wonderfully results in desalinated hot water, which is pumped to *massive* cooling lakes (not ponds... lakes...) creating an entirely new ecosystem with tons of available water. Place these power plants strategically so that the water is captured efficiently as lakes, creating freshwater rivers and streams back to the ocean. And thus we have a green Sahara. Oh, it would take *forever* to get the Sahara to green up. The world is full of lakes and reservoirs (e.g., Utah's [Strawberry Reservoir](https://en.wikipedia.org/wiki/Strawberry_Reservoir)) that are full of water and surrounded by nothing more green than sagebrush... (After *fifty years* there's still nothing more green than sagebrush around Strawberry Reservoir.) The point I'm making is that water is only one of a bunch of things you need to get grass and trees — and deserts lack pretty much all of them. But that's the subject of another question. Ocean water + cheap desalination = green Sahara... eventually. [Answer] Sahara's "Greening" probably wouldn't have no effect on Amazon. 6000 years ago to 12,000 years ago, Sahara wasn't a desert, but a subpluvial grassland with modest desert at it's tips. Lakes size US states, lake Chad was 50x it's size. At height of Holocene climatic optimum where average temperatures were WARMER than present. [![enter image description here](https://i.stack.imgur.com/e1MSd.jpg)](https://i.stack.imgur.com/e1MSd.jpg) Global Warming made Africa Humid. That all went away when planet got colder. But I digress, not political aspect. Terraforming Sahara into habitable permanent environment. [![enter image description here](https://i.stack.imgur.com/cvu30.png)](https://i.stack.imgur.com/cvu30.png) Stage 1: Process begins with reintroduction of water (Desalination) and pumping into it's major Aquifers. Saturation of water into the depressions of former lakes. Stage 2: Processing of the desert soil into organic containing soil biome. Organic material, compost, coconut husks, any water loving organic material is mixed into soil over time. Certain trees may be added in clusters. using a landscaping technique called "Zai" filling them with manure and compost to provide plant nutrients. The manure attracts termites, whose tunnels help further break up the soil and introduce more organic material deeper and deeper. [![enter image description here](https://i.stack.imgur.com/V2z7w.png)](https://i.stack.imgur.com/V2z7w.png) Stage 3: Tree planting. Water efficient but habitat worthy trees like Acacia and various native plantings would be best candidates. However GRASS, especially dominant in African ecosystems is better available choice. Over time the soil will be colonized with microorganisms with the constant introduction of organic materials, once tree's establish a tap root, they can thrive on natural rainfall. And the constant additional humidity from stage 1 will saturate soil to build a suitable biosphere. Stage 4: Animals: Dung beetles, worms, insects like ants and termites will be first candidates for introduction. ]
[Question] [ The simplest kind of space elevator would be a large mass somewhat beyond geosynchronous orbit tethered to earths surface such that the tether is always under tension from centrifugal force overpowering gravity, but I feel like the equator would be a problematic place to put it because of satellites and space debris. Is there any reason a space elevator can’t be put at high latitudes while still extending away from the axis of rotation? [Answer] The center of mass of your space elevator is going to need to be in the geostationary orbit, no matter where you put the base anchor. As a result, while you can put the foot elsewhere other than the equator, at least at that center-of-mass point, it will be over the equator. Well, technically, a bit higher than that; the whole point of a Space Elevator is using the tension of having the center of mass *above* the synchronous orbit to pull up the rest of the structure below it. Either way, though, it's going to have to pass through the equator... because *all* orbits pass through the equator. And if your space elevator doesn't have a point on it that traces out an ordinary Keplerian orbit where you can put your docking station, warehouses, and so on at (which is typically that geostationary orbit), you've decided not to use the primary utility of building one in the the first place. And if you're building a space elevator, you're committing to doing *something* about satellites and debris in orbit around your planet, regardless of where the foot is, so unless there are political, geographical, or logistic reasons preventing you from putting the base on the equator, might as well put it there so you don't have to make it longer than you need to. [Answer] **The easy answer is "no, it's just a lot simpler and cheaper"** The Earth is spinning and you're taking advantage of that spin to create your elevator. On the equator, the forces along the shaft of the elevator (ignoring things like climate) are perpendicular to the surface of the Earth. When you're lifting, you can take advantage of the maximum centripital force to minimize energy costs. When descending, you can take advantage of maximum gravity force. At the poles you have a little less efficiency, but still some advantages. The elevator is still perpendicular to the surface of the planet, but you no longer have the advantage of centripital force when you lift the car. We'll ignore the twist to the story due to the rotation of the planet — it's not that big a problem. But if you put that elevator *anywhere else,* benefits decrease and problems increase pretty quickly. **let's anchor that sucker on the Tropic of Capricorn** Let's assume that [Australia gets its knickers in a twist](https://youtu.be/qzpkF7A0uII?t=11) and decides to throw the proverbial bird at the whole world and build its own elevator — smack dab on the Tropic of Capricorn. Now what happens? The elevator won't be perpendicular to the surface of the planet because the planet's surface is curved and the force wants to push the elevator straight-out from the axis of spin. That makes it, what, lean more-or-less 45°? This puts uneven stresses on the elevator, exacerbates climate effects, and basically throws half of the benefit of gravity out the window. (You still get centripital force, though!) But what does all that translate to? *Cost!* **In the fight between physics and economics, economics wins more often than you might think** When the Obama Administration pulled the trigger and disallowed manufacture of 60, 75, and 100 watt incandescent bulbs, it caused people to howl! Was it the right choice? From the perspective of forcing people off of the addiction to energy-hogging incandescent light bulbs and forcing them to use energy-efficient LEDs, yes. *But from the perspective of forcing people to stop using cheap 50¢ light bulbs in favor of, at that time, still very expensive (\$20-\$50) LED bulbs, no!* People on fixed incomes were unimpressed with the argument that LEDs would last longer. They couldn't live without light waiting to save up to buy one. Cost is a big deal, and the cost of building and maintaining a space elevator at the equator is as cheap as it gets. It doesn't hurt that in many ways the climate effects are also minimized. But build that darn thing anywhere else, and you must be prepared to pay for it. --- **Edit** A number of commenters have suggested that centripital force can be ignored. Well... kinda. There's a tether between the top of the elevator and the base. It's not enough to simply get the top of the elevator moving in a valid orbit — you need to keep it there with the drag of that tether due to everything from bad weather conditions to centripital force. Yes, you could use thrusters to do that... *at a cost.* Every dollar spent to keep the elevator operating away from the equator is a dollar that didn't need to be spent. [Answer] As noted in other answers, while the center of mass of the tether (the core of the space elevator) must be geostationary (hence, above the equator), the anchor point at the surface need not be -- but there's a limitation on how far from the equator it can be: the excess strength of the tether material. Every degree the foot is moved north or south of the equator, is a degree of off-plumb attachment in the tether, which increases the tether weight (which is one of the limits -- the tether must support its own weight, that of the counterweight, the elevator structure, and any payload on the elevator, plus weather loads -- likely very small relative to static and dynamic loads from normal operation, but need to be considered) and introduces shear loading. Any mechanical or materials engineer will tell you shear loading is bad, when you're operating near the absolute limits of the strength of your material (and you will be). Shear itself is bad enough for a tensile-only material like the carbon nanotubes currently considered the best candidates for tether material, but it introduces a biaxial load (both shear *and* tension) which unavoidably weakens the material, which is already pretty weak in shear. While I've read that *IFF* we can produce carbon nanotubes in lengths of tens of kilometers, defect free, and bond them together into cable without weakening them, we can pretty readily make a space tether, I've also read that there's not a huge safety factor in the strength. If you choose to handwave a super-material (like Niven's *scrith* or Sinclair monofilament), you make your own rules, but if you're abiding by real world physics, every 95 km (~ one degree) you move your base anchor away from the equator will have a disproportionate effect on the tether's ability to support space elevator operation. There's one potential practical exception to this: if you mount a large enough solar sail at the top of the "beanstalk" -- well beyond the neutral point, out at the counterweight -- you might be able to continually adjust its angle to provide a reasonably constant force pushing the top end out of an "orbit" and into a powered path in a circle that doesn't cross the equator. How big your solar sail can be, and how much northward or southward force it can produce would determine how far off the equator your anchor can be and still keep the tether locally vertical. There are other engineering problems to be solved in doing this -- not least that I don't have the math to calculate what it would do the stresses on the tether or the anchor point -- but it's at least not a violation of orbital mechanics; in fact, it's akin to the situation we already have with a beanstalk where we use a counterweight at greater than orbital speed to keep tension on the tether. [Answer] ## If strictly ideal, then yes equatorial. If it is desirable to have the idealized ladder that has a fixed earth connection, it must be geostationary which requires positioning above/along the equator. ## If not touching earth, no. If it is acceptable to have the earth end mostly in one region with **no earth contact**. Ie earth end sits at an elevation 10 to 40 Km above earth. Then geosynchronous orbit is a reasonable possibility/option. The high elevation makes a big difference to ease of construction thus cost. ## Space hooks could be almost wherever. If center of mass is not at geostationary level/height. Then it would be more correctly labeled a space hook and a space hooks can be in many more possible orbits. Also a small space hook can be constructed and placed into orbit within five to ten years if any of the major space organizations decided to prioritize it. Space hooks would only make ground momentarily if they do, majority would have closest approach to earth measured in kilometers. Cost to orbit would be the price of a flight of a high altitude aircraft. ### Other satellites, debris is an issue for all. [Answer] I am surprised no other answer spoke about that (maybe I read to fast), but in the original designs I read, the best place for the "space port"/anchor on earth (if you choose to have it at "ground" level) is neither on the equator nor any other static place, but a platform in the ocean that can move on the surface of the earth. That way : * you can move it to avoid debris/satellite in orbit * more importantly, you can avoid storms. In most designs, the tether is a nanotube fiber, which is, among others, extremely sensible to high temperatures that could be caused by lightnings For more information about the concrete prospects of these space elevators **on earth** and why it is supposed to be anchored in the oceans, there is the [2003 Nasa Study](http://www.niac.usra.edu/studies/521Edwards.html) (this is an old project) and the [last 2021 engineering study from ISEC](https://soe.rutgers.edu/sites/default/files/imce/pdfs/gset-2016/FINAL_Space_Elevator.pdf) [Answer] Almost all of the answers presume that the elevator has to stay in place. (Thank you, @Carm) This isn't the only answer, it's just the best one. An alternative answer would be to have the bottom of the platform perform a figure-8 over a set area of land. If a geosynchronous satellite isn't directly over the equator, it will make a loop over an area every 24 hours. This could be used to take advantage of multiple launch points, with a "space hook," or landing platform that would grab the flying craft and drag it upward. The challenges of this design are that you have to perfectly balance the orbit so that the end of the tether drags through the atmosphere. The size of the loop would be largely limited by atmospheric drag on the tether which, over time, would attempt to drag the counterweight back to earth. [![enter image description here](https://i.stack.imgur.com/TvNii.jpg)](https://i.stack.imgur.com/TvNii.jpg) [Answer] **Not necessarily** While it is necessary that a tethered space elevator must stay on equatorial orbit, there is no necessity to *attach* this elevator at the equator. @Zeiss Ikon is quite right to point this out, let's me elaborate a little bit more on this. Think about [Tetherball](https://en.wikipedia.org/wiki/Tetherball). The ball is attached to the top of a pole, but its plane of rotational does not contain this top - the ball spins somewhere below it. Similarly, it is theoretically possible to design a space elevator which center of mass sits on geostationary equatorial orbit, while its tethering point is located anywhere on Earth's surface. Moreover, our space elevator can have *multiple* points of attachment, which can be very useful if multiple nations are sharing the same space platform. What's complicates things though is tether's own mass. Ideally, we should have massive space platform and nearly massless cable, but realistically this is not possible. All space elevator design require massive cable, if this cable is not vertically upright, things get complicated. Now think about tetherball on a massive iron chain. It would still spin, but its behavior would be different. Overall, the requirement to attach the tether not on equator can be a project killer. [Answer] ## space elevators work best at the equator, and at the poles, and everything else is chaos Considerations about satellites are valid, but once someone is investing in a space elevator they can invest in satellite cleanup or protection. What you want to consider is the strain caused by the orbit. In an equatorial elevator the strain works in your favor, the constant angular speed at the end of the elevator pulls the whole structure up. The orbit is circular, and in line with your structure. In a polar elevator you have no orbit and so no strain to keep the elevator in place. This isn’t good, but a strong enough elevator can support itself. Further more, the elevator just holds itself upright with very little other strain. In a non-equatorial and non-polar elevator you have a problem. The end and the center of mass have circular orbits, but not in line with the center of mass of the earth. This means that your elevator will strain towards the equator as the elevator tries to follow a normal orbit and has to apply radial force to maintain the different orbit. This means that the force you have in the each direction is based on the azimuth of the elevator in relation to the earth. The upwards direction is the cos(azimuth)\*cos(azimuth) of the azimuth, and the sideways force is the cos(azimuth)\*sin(azimuth). So to maximize upward force, azimuth must be 0. To maximize the sideways force, you sit a 45 degrees of the equator, and have half the normal upwards force in the sideways direction, and only an equal half in the upwards direction also. Near the poles at 90 degrees the upwards is zero, but so is the lateral. Therefore, build at the equator to get to equatorial orbit and for low cost elevators, build at the poles for polar orbits and high strength elevators, and build anywhere else to flex on Kardashev type 1 civilizations. [Answer] If you have multiple base stations, the orbiting part of the elevator can be above the equator, with two base stations, both equidistant from the equator at opposite latitudes. It should be simple trigonometry to figure out how far from the equator the stations need to be to make the tethers miss the most debris-filled latitudes. Basically the tethers make a big "A" shape with a ring of debris passing between them. It could also be possible to move the orbiter by varying the lengths of the cables. Reeling in the cable at the north base and letting out more cable at the south base will move the orbiter north. Reeling in the cable at the south base and letting out cable at the north base will move the orbiter south. If you have 4 ground stations, you can move the orbiter east and west as well. [Answer] An elevator cable anchored away from the equator (let's say north) will form a curve asymptotic to the equatorial plane. It will not be straight, because it is not ‘vertical’ with respect to the forces on it; and its top end will be some small but nonzero distance north of the equator, because of the northward component of tension on it, balanced by the southward component of Earth's gravity (which is zero on the equator). Centrifugal force pushes away from Earth's axis, not its center. There must be a maximum latitude for the anchor, at which the sag makes the cable tangent to the ground. I lack the skill to find what that latitude is; it depends on the amount of taper in the cable. ]
[Question] [ Do you know how (almost) every cyberpunk story happens in a dark rainy night? No matter how long a timeframe the story takes place in, it's always rainy and dark. How realistic is it to have a planet like this? To make it more clear, this is a planet that has 3 things about it: 1. It's always rainy on it 2. It's always dark on it 3. A human being can live on it and walk outside without a spacesuit/air tank/etc. After posting this I got the related question of [How can I explain a planet with perpetual rain?](https://worldbuilding.stackexchange.com/questions/14300/how-can-i-explain-a-planet-with-perpetual-rain?rq=1) which answers #1 well enough for my taste, but that still leaves #2 in a way that isn't a problem with #3. How can a planet be always dark, yet warm enough for a human being to live outside on the planet's surface? [Answer] **The City Creates its own Climate.** CyberPunk stories happen in big cities. So you only need the cities to be dark and rainy. Not the whole planet. Here is why: **2.** The city has narrow streets and tall buildings. Not much light reaches the streets. **1.** There are loads of industrial factories around the city. They spit out heaps of steam and exhaust gasses. Similar to a rain forest these gasses hit the colder air above, and condense and create rain. Bonus points for pollution also making the streets darker. **3.** The pollution gas is too high up to reach the streets and breath in. It only hits people in the form of acid rain which, while dangerous, is less of a danger to breath in. Better technology ensures the pollution is cleaner than modern pollution. We have environmental boards for that sort of thing for cripes sake! The exhausts are mostly steam and a mix of high-tech chemicals, microplastics and nanobots that do not cause immediate lung irritation. Rather they cause long term cancers, genetic problems, and depression, in order to generate business for the Dystopian Pharmaceutical Industry, which makes generous donations to the environmental board. But there is nothing that will cause immediate discomfort to a resident. [Answer] **This is a doozey!** You don't specify how dark you want the planet, but the idea of a habitable planet that doesn't have a sun (vegetation...) is hard for me to swallow. That means either a dim sun so you can have vegetation or a lot of cloud/dust cover to block out most of the visible light. The benefit of the cloud/dust cover solution is that you're trapping heat. So, how do we get a ton of cloud cover? Well, unless you have a steady stream of ice-asteroids breaking up in the atmosphere to provide "rain," you need either something pushing water into the air (the geysers from the selected answer you linked to) or you need something along the lines of *evaporation.* Blocking or limiting sunlight makes traditional evaporation difficult... but if you have geysers, would one not have vast swaths of volcanism? I'm not talking a penny-ante ring-of-fire kind of volcanism. I'm talking about a healthy Yellowstone Caldera worth of boiling magma right in the middle of the ocean boiling water into humidity galore kind of volcanism! And you want a dozen of them planet-wide! Provide higher-altitude land masses for the lush vegetation and you have a dark and rainy planet that's also warm. Could a human inhabit such a planet without some kind of suit? Other than a bathing suit? Or a wet suit? Sure! But they might have moss growing in their lungs. Let's ignore that. [Answer] ## Lucky sun, lucky orbit, happy cyberpunks Your planet is in tidal lock (one side to the sun 1:1) orbiting around a relaxed, brown dwarf. There is some UV, but that's only on the bright side. That side is 600 degrees, no cyberpunk will live there.. the dark side is cold and variant (see below) Between the dark side and the bright side of the planet there is a large, moderate zone, but the cyberpunks don't like it, for its hot climate and the reddish-orange evening light. The moderate zone is only used for agriculture and populated by robots. **Vulcanoes** This planet has a *lot* of vulcanism, cyberpunks love it. On a good cyberpunk planet you need fireworks and your regular spectacular disaster. Near some volcanoes, the temperature is nice. On top of them there is snow. When the colony started, they had winter sport resorts, these are abandoned nowadays. Cyberpunks don't do sports. The volcanism provides plenty of heat. There is no energy problem and cyberpunks live indoors, near their computers. There is some traffic between the cities, but life is mainly online. **Open mega structure to circulate the water.** Their cities are all on the dark side. The atmosphere, containing lots of water damp, remains contained an open, spider-shaped mega structure. The mega structure, spanning the dark hemisphere, looks like a huge spider, consisting of straight walls. Corridors extend to the moderate zone, where the agriculture is. It has blowers along these corridors, moving air and moisture to the plants. Wind and clouds move through these corridors, melt the water and when it arrives, misty rain will feed the plants. These blowers generate a loud, continuous noise, cyberpunks love it. The mega structure has a central part of about 400km diameter, which contains 6 volcanoes with nice temperature. There are several cities, where extra water is synthesized and evaporated. The water damp concentration is highest there, it will go up and find the cold atmosphere. It condensates and falls down as snow, that will melt underways. Result is a constant, slight rain. **Party all day** Your cyberpunks are vegetarian (of course), their robots harvest food in the twilight zone and the inhabitants prefer to remain in the dark cities, having parties. [Answer] On Earth you might be looking at a combination of catastrophic climate change (which we're on course for) and desperate attempts to geoengineer around it. This might mean that: a) The warmth in the atmosphere causes more evaporation which has resulted in a huge amount of cloud cover. To try and mitigate the amount of heat and keep the surface survivable humans have released a huge amount of reflective gasses into the high atmosphere, resulting in greatly reduced sunlight even during the day. b) The force of the storms roaring across the landscape has forced the building of Arcologies- massive cooled domes cover our cities, darkened against the blazing sun. The evaporation from the cities strikes the domes and condenses, falling back as a relentless rain on the benighted neon-lit streets. [Answer] **A Tidally locked planet.** One side is permanently scorched, the other half a hellscape of ice. The only actually inhabitable place is the dawn/dusk ring between the two extremes. It's ridiculous to think that an entire planet would have to be so homogenous, an entire planet-wide city, just desert all around, all jungle? Star Wars did us dirty here. But no, it's a regular planet, tidally locked. The areas with permanent intense sunlight are used as farmlands and/or resort places for the rich, and the further you get towards the dark side the poorer everyone becomes on average, because everyone who can afford to moves towards the sun. [Optional: Gated Communities, a classist metro (if it even exists) and so on prevent poorer people from doing day trips towards the sun, meaning they stay in the twilight their entire live if they don't make it rich.] And this intense pressure to "make it", to see the sun (for more than a couple of hours a week), is what brings about the cliché scene of cyberpunk crime-professionals, big deals and odd jobs. [Answer] Heavy air pollution and remaining pollution and radiation from previous wars( probably nuclear wars) in Cyberpunk stories along the lack of trees may had made daytime dark and gloomy. But it varies from story to story. in Cyberpunk 2077 the weaher is sunny and it rarely rains and there are a lot of vegetation. [Answer] Go watch the movie "Angela's Ashes". The majority of the scenes are set in gloomy rainy weather. [Here's](https://www.endesa.com/en/blogs/endesa-s-blog/others/cities-hours-sunlight) a website that documents most/least sunny areas. Have fun with it. ]
[Question] [ For a science fiction setting I'm working on, I'm trying to make a clear division between ships made exclusively for space flight, atmospheric flight and dual-purpose ships that can fly in both. The most common example I would imagine for these dual-purpose ships are freighters that travel between planets and the fighters that escort them so they don't have to recall their fighters for entry and then deploy another set once in atmosphere. Unfortunately, I'm no expert in aerodynamics or 3D modeling, so my ship designs are kind of boxy and often a joke in aerodynamic design despite my [best efforts](https://www.deviantart.com/arvex/art/IWE-Modular-Fighter-S-configuration-838182252). The linked image is probably what I would consider one of my more aerodynamic designs that I've published a render of, though it has an atmospheric variant I'm working on that would have more aerodynamic wings and engine pods. It got me thinking, though, maybe I could find a way to make this work within the confines of this setting. Could a combination of cheap energy and powerful thrusters allow a ship to overpower poor aerodynamics to the point where starship manufacturers can get away with cutting corners on aerodynamics to cut design and manufacturing costs? The thought is that making fighters capable of surviving re-entry would be expensive, so they might want to cut costs elsewhere or it might become cheaper for freighters to carry two sets of fighters and go through the hassle of switching fighters as part of re-entry procedures. I still intend for dedicated atmospheric craft to have an advantage over these dual-purpose ships, but I want them to be good enough that a skilled pilot could believably overcome that disadvantage. These ships would likely be traveling at speeds comparable to modern jet fighters, maybe a little faster. The limitation is still going to be the forces exerted on the pilot as I don't have any kind of "inertial dampener" style tech in this setting. Clarifications: * This question is more focused on fighters and smaller craft. The freighters themselves will likely need to be more aerodynamic or have to flow at much lower speeds. I'm mostly focused on the smaller ships because they would need to intercept any oncoming attackers. * I'm not looking for suggestions for alternate designs. I'm simply trying to find out if my existing designs aerodynamic shortcomings due to my own lack of expertise in the field can be justified in-universe. * The speeds in question would be more in the combat speed range than cruising speeds. * The dual purpose atmospheric+space use fighters will still have an attempt at aerodynamics. They won't be flying bricks. The idea is that the manufacturers might not put anywhere near as much time and effort into aerodynamics as we do any modern aircraft to cut costs. [Answer] The brief answer is “no”. At fighter-jet speeds, overheating from atmospheric drag is also an enormously important issue, so even if you have an engine that needs no fuel at all, you still have to be aerodynamic. [Answer] ### Totally possible - Your energy abundance results in you travelling *MUCH* slower than current space missions. Space isn't that high up. The ISS is 408km above the ground. If it was horizontal you could get there in a car at highway speeds in 4 hours. Space as we know it isn't high, its FAST. That ISS is travelling at 7.6km/s. It needs to do that speed to maintain an orbit. If it slows down, it falls out of orbit. To travel any slower it'd need to be constantly thrusting upwards. Re-entry as we know it is a transfer from LEO using minimal fuel in orbit to subtly perturb the orbital ellipse so it skims the atmosphere, resulting in spaceships hitting the atmosphere at hypersonic speeds. Because of these hypersonic speeds, aerodynamics is everything. However, if you have an epic power supply, you don't need to conserve fuel. Because you don't need to conserve fuel, you don't need to travel at 7.6km/s. You can travel at car speeds. You could fly upwards at 100km/hr for 4 hours. Stop at 408km in altitude, keep the engine trusting upwards at about 1g, and watch the ISS shoot fast at bullet speed, and think "Hey that's soo cool", then return home, never having exceeding 100km/hr. 9 hour total journey. Because you don't exceed highway speed in the atmosphere at any point, your ships can be as aerodynamic as anything you see on the road. --- You can of course travel faster when in the vacuum of space if you want, just remember to follow your crafts atmospheric speed limit during re-entry, otherwise you will burn up. --- Note that obviously the freighters and fighters travel at approximately the same speed. Remember if the freighters are travelling at 100km/hr then their escorts are going to be travelling at ~100km/hr too to stay close. An interceptor sent out to get them can travel at whatever speed they want, but if they're travelling much faster they're going to overshoot. All battles takes place at highway speeds because no-one needs to travel at hypersonic speeds, nor gets any benefit to doing so. [Answer] Here's the thing-- I don't see the aerodynamic issue as so much a matter of cost as one of fuel. The less aerodynamic, the more fuel the ship will spend when in an atmosphere, and the lower its range. On the other hand, the more you add wings and whatnot to make it aerodynamic, the more fuel the ship will spend when *out* of the atmosphere (because it weighs more). So if you want to favor less aerodynamic fighters, I'd say the best justification would be to **make their primary use maneuvering in space**. This is especially justifiable because space combat would likely take more fuel than aerial combat, and need more optimization toward it. That way the economics justifies optimizing to have less aerodynamic gizmos in favor of more room for fuel and thrusters for more efficient maneuverability in space. Also, optimizing for combat in a vacuum allows you to have battles over planets with little or no atmosphere like Mars. Hope that helps! [Answer] **Proposal:** 1. Freighters are totally nonaerodynamic agglomerations of containers and other structures. They use the thrusters to slow from orbital speed on re-entry and then schlep along wastefully thru the atmosphere. Maybe they even come down into the ocean and turn into boats. They try to come down close to where they want to be. 2. You do have space fighters and atmospheric fighters. The atmospheric fighters are carried aboard the freighter and emerge when there is enough atmosphere. Some might come up from the port and escort the freighter in. The space fighters are nonaerodynamic spheres. There is a point during (the slow, slow) freighter re-entry where the space fighters have all come inside but the atmospheric fighters are not out yet. That is when the pirates come, and these are the ones that have the dually able ships. Those ship need to stay in their narrow zone because they will be outgunned by either the space fighters or the atmospheric fighters. [Answer] **I give you, *Battlefield Earth*** *The book, not the film, which stank so badly that it could be smelled in the Antarctic.* L. Ron Hubbard faced the very same question and came up with the very same response. He had a fundamentally undefined unlimited-energy source combined with the coolest idea on the planet: teleportation engines (the space inside the engine teleported, producing motion). But the tech was being used by the Psychos, who were a remarkably uncreative but entirely capitalistically-driven species. And they not only had energy and thrusters — they also had nearly indestructible metal. It didn't matter to them ***at all*** if anything was particularly aerodynamic. What mattered is that they were inexpensive and disposable. **And this is the point of my answer** Economics have as much (and occasionally more) to do with design than aerodynamics. Planes are shaped the way they do only because they're needed to be so to keep them in the air. If we had some kind of gravitics keeping them afloat, they'd look like buses because that shape is a whole lot cheaper to build. So, if your world has an ignorable economy, shapes will include aerodynamics because people can afford both the artistry and the benefit. If you don't have an ignorable economy, then cost will limit just how aerodynamic anything will be. The balance will be, "can I move it enough with acceptable losses to gain the win I desire?" because anything else will cost more. [Answer] If you have no fuel budget and your materials are strong enough to withstand aerodynamic stresses then the shape of the fighter is not hugely important To Quote Enzo Ferrari: > > “Aerodynamics are for people who can’t build engines.” > > > Your differential in Space vs atmosphere fighters is more likely to come from weapon fit. In space the best weapon fit might be lasers, whereas in atmosphere these might not be as effective so missiles are the best choice. The skill of you pilots could be in using the suboptimal weapon system. [Answer] ## The perfect dual-purpose fighter: A Sphere Having limitless energy means that you can deorbit and land pretty much anything with the structural integrity to stay intact in gravity. Aerodynamics only limits how fast you can move in-atmosphere, as long as you don't mind a snails-pace you can land even the most ungainly of ships. I believe it's been explored in a different question, but the ideal manned space fighter should have it's thrusters, weapons, and cockpit all able to rotate independently, in order to maximise both manoeuvrability and G-tolerance (so that the pilot is always "Eyeballs In"). A space-only fighter can be cheap and lumpy with random stuff bolted on, but if that goes into atmosphere and tries to move at anything resembling combat speeds it will tumble uncontrollably. The solution then, is to make sure that all that hardware fits within a spherical hull. It would be less flexible in loadout and modifications than a dedicated fighter of either type. Also somewhat less space efficient than a brick-shaped space-fighter, if that matters. A sphere has decent aerodynamics and, most importantly, no preferred aerodynamic orientation. The fighter can still rotate, thrust, and fire in all directions without the air trying to pull it a certain way. Lacking wings just means has to adjust its thrust vector to account for gravity. You can even easily slap on a detachable hemispherical heat-shield for when you need to reenter at high speed. ]
[Question] [ **This question already has answers here**: [Why would people bury their dead in tombs when they might become zombies?](/questions/168032/why-would-people-bury-their-dead-in-tombs-when-they-might-become-zombies) (23 answers) Closed 2 years ago. In the majority of the modern fantasy worlds the dead are buried in crypts and tombs. At the same time, these places are frequently crawling with undead - skeletons, zombies, etc. I understand religious aspects of burying the dead, but in a world where the undead are fact, surely practicality would take over and the majority of the dead would get cremated. What other (practical ideally) purpose could be devised for the bodies to be instead religiously cleansed and then buried? [Answer] **Contamination**: As illustrated in *Return of the Living Dead*, burning the 'corpses' spreads zombieness further. **Nastier alternatives**: Per Skyrim's Ash Spawn, the magic that would reanimate zombies reanimates burnt ashes into something even more hazardous. **Power generation**: Cleanse and bury the dead, sure, but first chain them up to Conan the Barbarian style manual generators, whose shafts protrude from the crypt you've sealed to electrical equipment above ground. No sense having a zombie apocalpyse and a climate change apocalypse at the same time. **Bioremediation**: There are only so many evil spirits in the world. Trap them in dead people incarcerated securely in coffins (or power generators) deep beneath the earth, and the world can go back to normal. **Ecosystem services**: Powers that be find that the zombies are doing a service in keeping human numbers manageable. **Honor**: In the steady state of ecologically sustainable population replacement, there is one zombie "born" per person born. Destroying one zombie by dishonorable means means that one of the young warriors will *never* have the chance to pass his or her initiation, because there is no zombie available to be captured and ritually incinerated to show their hardness of character. [Answer] Here's my take. In almost all religions nobody gets upset if you bury the body because you don't know what to do with it. Many do if you do burn it when it wasn't supposed to be. (Also cremation is time consuming and resource consuming.) It's a lot simpler to just tie the body down and then maybe cut a few major tendons/break some bones before burying it then it is to gather up the resources for a cremation. Also some ghosts are really upset because there body wasn't buried. Imagine being plagued for life because you can't bury the body! (Having burned it.) So 1: It's expensive to burn bodies enough that no undead can pop up and 2: And two not everybody wants to be burnt and will come back to haunt if you do. [Answer] You could always place the recently deceased into wooden boxes that are nailed shut and bury them under 6 feet of dirt. For bonus points fill the box with dirt or sand before sealing it and lowering it. This will prevent the body from being able to move at all if it revives. If the coffin does break, dirt can't pour in from above that way, so the undead will have no wiggle-room to escape. To be extra sure, you could always put some rocks ontop of the box. Dirt is extremely heavy and moving through it is not as feasible as zombie movies would have you believe. [Answer] **Holy Ground** If undead exists then God could be real and religion has an actual purpose. If a body is blessed and buried on consecrated ground, it cannot arise as one of the undead and the soul is at peace. [![enter image description here](https://i.stack.imgur.com/7A52G.jpg)](https://i.stack.imgur.com/7A52G.jpg) If a body isn't interred properly, a necromancer can raise the dead. Cremation works mostly because it's hard for the necromancer to find the remains but if they do, they can still trap the soul as a wraith. The only way to be sure is blessing and burial on holy ground. [Answer] ## What's So Bad about the Undead? Burial practices in various places around the world are complicated. There is evidence in Skara Brae, the living visited the dead (after being de-fleshed by birds), often handling them. The Malagasy believe they need to dis-inter the dead and show homage, and that the dead don't rest until the body has decayed (anyone from Madagascar, feel free to edit this to be more correct). In a world filled with death, ties to the dead can be essential to dealing with life. Where the undead are real, so too is the body a conduit for the dead to communicate with the living. The living feel the dead are close by, not really gone. One of the risks, obviously, is if someone other than the deceased takes up residence in the body. The very FACT that there are undead proves the connection! So rituals to protect the body from possession would be prevalent, and people might reach out to the dead for everything from approval of life choices, comfort, or even just asking Grandpa where he buried the money. [Answer] **Re-animation is rare and preventable** Although it's possible that your cadaver will be re-animated by a necromancer or some evil spirit, it's not something that usually happens. Most bodies remain in the ground and don't come back to life as skeletons or zombies, so for most people, it's a non-issue. Of course everybody talks about the crypts and tombs that are crawling with undead, but nobody mentions the fact that the vast majority of corpses remain dead. A small chance of re-animation is not enough to dissuade people from their religious burial practices. This is somewhat parallel to the practice of graverobbing - even today, it's possible that your corpse won't remain in the ground forever, but it's still unlikely that you'll be dug up. The fact that you might not rest in peace forever didn't really discourage people from being buried, although it did lead to some interesting grave security measures such as the mortsafe, dead house, and grave guards. If you're truly worried about your body being stolen or re-animated, there are steps you can take to prevent it while still complying with your preferred burial ritual. [Answer] This is because modern fantasy is based on European medieval period and so influenced (even if subconsciously) by Christian belief that the body should be preserved for resurrection. Plus another major religion today, Islam, is even more strict about body burial. But throughout history the dominating view about the most prestigious form of burial changed a lot. For example, ancient Greeks and Romans were burning their dead and burying the remains in ceramic urns and boxes. Similar situation was in middle bronze age in Europe - cremation was absolutely dominant form of burial. So, there is no reason other than writer background that fantasy world would have preference for one burial method over the other. What's more, cremation do not prevent from having extensive burial architecture as sometimes massive structures were built for jar sized urns and those were often filled with rich grave goods. [Answer] The thing is in a lot of fantasy universes cremation is considered standard practice for burial, specifically because of the threat of dead people returning as undead. There was some major fantasy franchise where zombies were the main threat that had this as a plot point, I thought this was *Game of Thrones* but that doesn't make much sense given how most families are shown to have crypts. *Game of Thrones* does do a good job in showing why cremation would pretty much be standard practice in any fantasy setting with undead. Burying bodies the traditional European way does nothing but provide potential armies for necromancers to use against the common folk, and because so many major cities and castles have crypts where they bury their dead deep within their fortified territory these crypts are basically massive trojan horses where a necromancer can subvert their defenses from within. In these kinds of cases the practical benefits of cremation would far outweigh any moral or cultural benefits of traditional European burial (or even other burial methods such as ossuaries or sky burial), simply because it is a matter of survival. Those who didn't practice cremation would be wiped out. Disposing of possible undead by cremation even has some parallels in real life customs such as Norse funerary customs where it was believed if not properly disposed of the dead could return as a draugr, so they were burned to prevent them from returning as undead. Reasons why the dead aren't burned can be religious or economic in nature. In Iceland where cremation was more expensive than burial due to wood being expensive they resorted to other methods of "preventing" the dead from returning as draugr such as deliberately damaging or tying up the body in some way. People also avoided cremation in continental Europe, which is where many of the undead myths that have filtered into the "not-medieval Europe" fantasy tradition came from, mostly because of the Christian prohibition on cremation because of the belief that you needed your body in one piece when the resurrection happened during the Second Coming of Christ. That restriction has been relaxed in recent years but was still a big deal then, [which is why people generally didn't burn bodies despite a lot of folklore in that area at the time revolving around the dead returning to prey on the living](https://www.nationalgeographic.com/history/article/medieval-pandemics-spawned-fears-undead-burials-reveal). [Answer] Cremated ashes raised as undead become ash elementals furious at being burned, with an insatiable hunger for burning and consuming the living. [Answer] Another factor: Why are they rising as undead? I'll look at the Dungeons and Dragons world as that's the one I feel most qualified to deal with. There are basically two types of undead: 1. The ones animated by some magical ritual. While cremation would stop them from being taken from the graveyard it wouldn't stop killing people and animating them and it wouldn't stop animating animals. There's no real gain from denying them bodies. 2. The self-replicating undead. In this case there is a very clear benefit to burning those **who died at the hand of such a creature**, but no benefit from burning any other body. How often will there be such kills with someone around to bury or burn the corpse, though? In neither case does widespread cremation do you any good. [Answer] Cremating the dead doesn't stop them becoming undead. Ghosts. Wraiths. Shadows. If a being has reason to return from the grave, the lack of a physical body isn't going to stop it. An incorporeal enemy is harder to destroy than one that can be stopped by decapitation. ]
[Question] [ There are a few uses for ground-to-space lasers in science fiction settings. One is the [laser broom](https://en.wikipedia.org/wiki/Laser_broom), used to shoot space debris until it deorbits and burns up. Another is [beam propulsion](https://en.wikipedia.org/wiki/Beam-powered_propulsion), or sending energy to a launching spacecraft via laser. These technologies pose a pretty serious question; how do you prevent millions of people from going blind when they inadvertently look up at the sky? As I understand it, lasers can cause eye damage even if you aren't in the path of the beam due to scattered radiation and diffuse reflections. An obvious solution would be to provide laser safety glasses; in a small-scale, single-room laboratory, this works fine. However, I can't wrap my head around how you could possibly distribute enough glasses to reach *every single person on this half of the Earth*, and communicate to them when and where the laser will fire no matter their language or literacy level. This kind of logistics would require knowing the location of every single human being within a horizon's length, including isolated rural families, remote indigenous tribes, homeless folks, etc etc, and being able to send them protective equipment, time and date without timezone errors, direction, and an order to lock themselves indoors without windows. Plus, there are animals, who you can't just put safety glasses on. I've considered the unethical approach of having the government/corporation/military just ignore the people and animals they aren't able to reach, but I think this would be financial and political suicide in the age of social media. My question is this: how can you safely fire a laser at an orbital (or beyond) target without blinding millions of people? [Answer] Although laser light is collimated, the bloom it creates in atmosphere will not be. Any reflected light is reflected in all directions more or less equally. (Unless you have something in the air capable of specular reflection, and it's all aligned in the same direction - in which case, stop shooting your laser at the giant floating mirror!) Most of the light that doesn't reach the target is absorbed rather than reflected, and this is re-radiated in all directions as black-body radiation. The effect of non-collimated light falls off with the square of the distance from the origin. Even if the laser light is dangerous at a distance of a few meters, it won't be dangerous over kilometers. If it were, you wouldn't be worrying about blinding people, you'd be worrying about destroying your laser by superheating the air in front of it into plasma. It's probably prudent to avoid getting *too* close to the beam, but you shouldn't let people get too close to your space infrastructure for any number of other reasons. Rocket launch sites and testing ranges are usually built in fairly out-of-the-way locations for this very reason, and laser installations would follow suit. Inevitably, some animals (mainly birds) will wander too close to the beam and be harmed by the light and/or heat, but it should not be terribly out of line with other infrastructure. Environmental impacts are rarely "none", but in all likelihood it wouldn't be worth raising a fuss about. tl;dr: as long as you practice safety measures appropriate to an industrial site, you'll be fine. [Answer] When you read that laser beams are very well collimated, it doesn't mean they do not diverge at all. It just take them long distances to show some appreciable divergence, but they DO diverge. For example, in the [Lunar Laser Ranging experiment](https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment), the laser beam which is shot from Earth is no longer a point when it reaches the Moon surface > > At the Moon's surface, the beam is about 6.5 kilometers (4.0 mi) wide. > > > Just to give you a measure, every $10^{17}$ photons fired, only 1 is collected back on Earth (after the roundtrip). As you see, distance is your friend, spreading the laser beam over a large area. If you pick a frequency where the atmosphere is opaque, you have further attenuation. [Answer] **No need for goggles.** The inverse square law is out friend here. One of the things that makes laser's a danger to the eye, while other sources of light (lightbulbs) are not is that laser light is aligned into a beam. This means that even a modestly powerful laser can generate a much brighter point of light than a powerful light bulb where the energy is far more spread out. Now, when laser light scatters from these orbital debris and asteroids the light scattered will come out at all kinds of angles, and so it will spread out in all (or at least many) directions. Near Earth orbit is 20,000 km above the ground. Lets say a laser is hitting some debris or the back-plate of a spacecraft using laser-assisted launch at that height. Lets further assume (for simplicity) that the laser light is scattered evenly in all angular directions. So at the 20,000km mark the energy is evenly spread over a sphere with surface area of $5\times 10^{15}$ meters (a 5 followed by 15 zeros). On Earth sunlight has an intensity of about 1 kilowatt per square meter. To be as bright as the sun (as seen from the Earth's surface) the power you need to be comming off this piece of space debris is about $5\times 10^{18}$ Watts. This is 5 exajoules per second. Lets put that in perspective, according to wikipedia (<https://en.wikipedia.org/wiki/World_energy_consumption#/media/File:Japan_energy_and_GDP.svg>) the energy usage of Japan (I think only on the power grid) was about 20 exajoules in the entirety of 2010. This hypothetical laser is dissipating a Japan's worth of energy into *wasted* scatter light every 4 seconds. Now their are lots of assumptions here, factors of 10 or even 100 or possibly 1,000 could be altered by adjusting them. The biggest weakness is the assumption of even spread, the asteroid you are melting might have one big flat metallic facet that acts like a mirror. But the point remains, no plausible laser system operating in space has any chance of getting anywhere near outshining the sun due to laser scattering. I assume that causing widespread blindness would require reaching intensities in this kind of ballpark. Their are still dangers. If some computer error (or terrorist attack, cyber-attack, other problem) caused a laser to turn it beam to directly face the Earth then the danger is potentially much higher. A final point. If one found that the dangers were much greater than indicated by my estimates, and blindness was in fact a danger. Then a possible solution is to choose lasers that operate at a wavelength that is absorbed strongly by the atmosphere. This would have drawbacks (all the laser stations would have to be in space), but it would ensure that Earth was safe. [Answer] I agree with the observation about the benefits of the inverse square law to mitigating this problem. I add also that the wavelength of the laser's operating mode is also an important factor [![enter image description here](https://i.stack.imgur.com/I2FzU.png)](https://i.stack.imgur.com/I2FzU.png) Wavelengths greater than 1.5 $\mu$m are absorbed by water -- this makes them eye-safe since the water in the eyeball absorbs the radiation before it can damaged the rods and cones of the retina. If your planet based lasers operated in the pass bands at ~5.5 $\mu$m and ~6.5$\mu$m, were the attenuation is minimized, the energy would pass through the lower atmosphere with minimal losses and the inverse square law would refracted light would be too attenuated, both by atmosphere and viscous goo in the eye, to injure a passers-by vision. That said the laser systems would want to operate either atop mountains -- to lower atmosphere density and absorption -- or in arid places with low atmospheric water content. These two conditions will maximize the power transfer to the target. There would also be some concern with dust since it could absorb energy and flare in different wavelengths which could be in UV range. Think thermalized electrons or fluorescing mechanisms -- there are many processes available to cause matter to generate photons in response to energy. This [master's thesis](http://www.control.isy.liu.se/student/exjobb/xfiles/1909.pdf) discusses transmission and absorption of IR in the atmosphere, if you want more info. [Answer] > > how do you prevent millions of people from going blind when they inadvertently look up at the sky? > > > This is going to be really obvious, but... If the laser is on the ground and pointing at the sky, that means the light is going into the sky. In order to get blinded by a laser, the laser light has to go into your eyeball. That means you have to be *in* the sky, not just looking at the sky. Unless the laser accidentally reflects off a plane. So don't point it at planes, or the ISS. ]
[Question] [ In the mythology of the Lambas people of Zambia, there is a creature called the Ichisonga. It is a herbivore, and very rhinoceros-like in appearance. Upon hearing a hippopotamus, it allegedly sneaks up on the hippo and then stabs it to death with its horn. It has a similar hatred of elephants and will stand by an elephant carcass in spite until rots away. Imagine that the Ichisonga was a real creature, a species of rhinoceros inhabiting Africa. **Why would it - a herbivore - be so aggressive towards hippos and elephants?** There are cases of herbivores exhibiting somewhat predatory behaviour, like Cape buffaloes, which actively seek out, stalk and kill lion cubs and even injured humans, but why specifically hippos and elephants? [Answer] A tale of envy. **Hippos.** The Ishisonga remembers swimming as a cub: it loved swimming, it would dive beneath the water and feed on the lush and delicious water-weed, reveling in the cool splashy games with the hippo children; swimming was what it dreamt about, what made life worthwhile. Then time passed: it grew, its head heavy with horn, it became more and more difficult to keep it above the water; it could not dive for delicacies and return to the surface with such ease. Eventually it could not dive, could not swim. Its dreams were broken. Ichisonga was cast onto the dry hot and dusty land it hated so. At times Ichisonga would take a drink by the rivers and lakes, there would be the hippos - friends of youth, grown now. Their honking laughter would fill the air for miles around, taunting and humiliating Ichisonga. Bitter tears would be all the water Ichisonga would enjoy. Instead of the sweet taste of water-weed, Ichisonga vowed to enjoy the sweet taste of revenge for this betrayal. Since the hippo children were so lucky as not to grow horns, horns would be their undoing, so Ichisonga took the only weapon it had and ended their laughter, one by one. **Elephants.** Ichisonga wandered the lands in sorrow, envy and anger, feeding on tasteless dry grasses; thorny bushes would scratch and stab at its lips any time it tried for a succulent leaf - there were none of the sweet fruit Ichisonga remembered as a child and longed for the taste of. Ichisonga would see sweet fruit, out of reach in the high trees; the monkeys would drop the seeds with a trace of the sweet smell - so tantalising, but Ichisonga could not reach. The elephants would snake their supple trunks with ease to twist the lower fruit away from the tree, then to enjoy the sweet taste. Ichisonga was envious and even sadder. Ichisonga would wander the savanna, occasionaly stumbling upon the carcass of a hunted elephant, one caught by the big cats or a tribe, then would gaze longingly at the remains, imagining the snakey trunk grasping sweet fruit, imagining the taste, wishing there were a way for it to belong to Ichisonga, but there was no way, only more sadness, envy and anger for Ichisonga - and dry dusty grass. [Answer] > > Imagine that the Ichisonga was a real creature, a species of > rhinoceros inhabiting Africa. > > > Rhinos already behave like this and they are herbivores. They'll attack most things. Of course they lose against elephants but that doesn't stop them trying. Why? Nobody knows! > > Rhino versus elephant. <https://youtu.be/4sRlnNllql0?t=155> > > > Rhino against just about everything else <https://youtu.be/xL6CUdw84jI> > > > --- Edit > > Rhino vs Hippo (the Rhino's horn has been removed to prevent poaching > so it's not a fair fight) <https://youtu.be/1Fog6jeeAZk?t=92> > > > [Answer] It could be that ichisongas shared their territories with hippos and elephants for thousands of years and probably due to increasing competition, these ichisongas must have developed a territorial instinct. Probably these ichisongas waited around till the elephants and hippos rotted away to make sure that they were dead and that they won't be back to bother the ichisonga(elephants and hippos are quite the tanks).The hippos are already quite territorial and hence are quite dangerous the any ichisongas in that territory and elephants could probably decimate the ichisongas' territory. To combat this, it might have developed such territorial spite towards the hippos and elephants. ]
[Question] [ Could we fire a heavy, long (e.g., 50 meters), spear-shaped object into Europa's icy-surface from space and then, when momentum stops, gravity gradually moves weights down inside copper tubes the length of the object like electrical-generator components generating electricity to heat the tip for melting the rest of the way down? [Answer] The major limitation in this plan is going to be the energy of the objects that you let fall. All of the essential equations happen to have a cross sectional area term in them, so we can actually do some useful calculations: how far do you have to drop something to get the energy needed to melt a length of ice? Let's start with density. The best object to let fall is going to be the densest thing you can find. Osmium, at $22g/cc$ ($22000 kg/m^3$) is the densest thing we can muster. From physics, we know that the potential energy due to gravity of an object is $PE = mgh$. Substituting in $a$ for cross sectional area, $l$ for the length of the Osmium slug, $d$ for the density of osmium, and $L$ for the length of the spear, we get $PE=dalg(L-l)$. We also know that 1cc of ice takes a lot of heat to melt. Europa's ice is at -160C, and ice takes *roughly* 2J/cc-K to melt (actually it's 2J/g-K, which is a little different, but they'll be similar enough results for this back of the envelope exercise). That means it takes 320J to raise 1 cc of ice to 0C. We then need to impart 330J/cc or so to melt it (334J/g, technically... and again I'm handwaving the density because this is just back of the envelope). Put them together, and it takes $660ax$ joules of energy to melt a cross sectional area $a$ $x$ cm deep. To switch that over to meters of depth, it takes $66000ax J$ joules of energy if $x$ is written in meters. These energies will be the same, so $dalgL=66000ax$. This makes it clear that the cross sectional areas cancel, yielding $dlg(L-l)=66000x$. If we're limited by total length, $l+L$, a bit of calculus will show that the best results we get are when the drop length and length of the Osmium slug are equal, $l=(L-l)=\frac{L}{2}$, so we get $\frac{1}{4}dgL^2 = 66000x$. The gravity on europa is 1.31m/s^2. Thus now we get $7205L^2 = 66000x$ or $L=\sqrt{9.16x}$. Since we handwaved a bunch of stuff, I'm going to round it slightly to $L=3\sqrt x$ What does this mean? To get through the 19,000m we need L=413m. Now we've been rounding a bunch, so let's do it once more. Let's call L=500m. This means you have a 250m long slug of Osmium, resting in a half-kilometer long object. That's what it takes to really melt the ice, assuming everything goes absolutely perfectly. Practically speaking, you'll run into issues melting ice fast enough to not waste energy into the surroundings. You're likely to be talking about a kilometer long object! My personal recommendation is to *land* kilometer long spacecraft into ice sheets. Land them gently. Don't try to impact them. The structural effects caused by trying to plow through all that ice would be brutal. It is almost guaranteed that you will crumple those tubes you are relying on. Oh, and Osmium is very brittle, so you're likely to shatter your weights. [Answer] No Heating the tip doesn't heat the rest of the spear and the ice will just close and hold the spear along the rest of the shaft. I'm also doubtful a moving counterweight could generate enough energy to melt a path for the spear. Why not just do it like NASA has already planned? Land a lander on the surface that runs on a nuclear battery and use the waste heat to melt the ice. The lander sinks into the ice and keeps melting while the water above refreezes. Seems much easier than smashing a giant spear and hoping it will keep going based on a crude gravity based generator. [Answer] I don't think we need any special technique for getting through the ice. We have drilled about that deep through rock for oil right here on Earth. I think there are two much bigger problems to deal with. First, think about how big the equipment for drilling through ~10km of ice will be. Now remember you have to get all that junk all the way out to Europa. And once it's out there, you have to land it; and Europa doesn't have an atmosphere so you can't use parachutes. Look at how much trouble SpaceX has had landing mostly-empty boosters. Now imagine trying to land an oil rig ~630 million kilometers away. Second, what happens when your drill finally breaks through the bottom of the ice? The ocean down there must be highly pressurized; ~10km of ice weighs a lot after all, even in reduced gravity. So what's stopping that water from shooting up the bore hole at the speed of sound and destroying all your equipment? [Answer] Possibly. This is Worldbuilding.SE, not Space.SE. There could be a way to make your spear practical, we just need a realistic reason why it would (since the others have covered why it won't work outright). Let's start off with the ice sheets. [This is how NASA is envisioning the sheets and underlying ocean working](https://europa.nasa.gov/resources/36/thick-or-thin-ice-shell-on-europa/). The red areas indicate thermal currents under the surface (we know they happen from the ice jets shot into space, but not much else) [![Europa cutaway](https://i.stack.imgur.com/chQIv.jpg)](https://i.stack.imgur.com/chQIv.jpg) And that ice sheet is [estimated to be 19-25km thick](https://www.lpi.usra.edu/resources/europa/thickice/) by using the unique topology of its impact craters. But this tidbit is interesting > > There is strong evidence that Europa’s icy shell is somewhat unstable and has been (or is) convecting. This means that blobs of deep crustal material rise upward toward the surface where they are sometimes exposed as domes several kilometers wide (think Lava Lamp, except that the blobs are soft solid material like Silly Putty). Any ocean material imbedded within the lower crust could then be exposed to the surface. This process could take thousands of years, and the exposure to Jupiter’s lethal radiation would be unfriendly to say the least! But at least we could investigate and sample what remains behind. > > > So the ice isn't static but shifting over time. Let's say we combined some elements here. The following has some plausibility to it (even if it is unlikely) 1. NASA detects an asteroid on a collision course with Europa with enough time to launch a probe 2. The asteroid strikes a thermal vent If your spear followed close behind the asteroid, there could be just enough weakness in the ice at the impact crater to get your spear through. ]
[Question] [ Similar idea to [this post](https://worldbuilding.stackexchange.com/questions/55794/why-would-civilizations-with-advanced-technology-still-use-castles), why would an advanced civilization able to create AI/ droids ranging from 'hardshell' (I-Robot (movie) or C3P0) to 'soft' (Bishop (Aliens)) still have use for melee combat, and the implements to accompany it (plate armor, swords, etc)? In this scenario, I am expecting ranged weapons (firearms, lasers, bow/arrow) to also be present in some capacity. It is general practice for both AI and 'real' humans to often use or prefer melee combat. While some magic is present in the form of typical d&d style, precious few are able to wield and manipulate it (less than a tenth of a percent of the population), hence the main prevalence of technology over magic. There is some melding of magic and technology, but it is incredibly unstable and unreliable up to this point [Answer] > > The slow blade penetrates the shield. > > > (Thanks Brizzy!) This quote comes from Frank Herber's *Dune*, and it is probably the archetypal example of what you are looking for. In this series, Herbert specifically wanted a world where melee combat mattered, but there was technological interstellar travel. To accomplish this, he invented the shields. The personal shields were normally in a "down" state, which let air enter the shield's volume. However, anything fast moving immediately raised the shield, preventing anything from entering (you could get light headed from low oxygen levels inside your shield in a protracted fight). The result was a melee combat style which involved slow movements of a knife to get inside the shield, followed by a quick killing blow. Herbert wanted the combat to be personal, which points to a second major reason one might choose melee weapons. > > "All can be redeemed." - Praetor Fenrix VII > > > Melee weapons may be preferred in a highly advanced society which has grown to deeply respect the value of life. Killing is a big deal, and it may be an even bigger deal for some advanced species who have gotten to see just how much can be lost. But even the most advanced species can't help but spill blood at some point. For this, such a society would prefer the opportunity to redeem the opponent, all the way up to the last moment. With a ranged weapon, your ability to craft such an alternative ending is limited. You pull the trigger, a hole appears where their brain matter was. One, two, the end. With a melee weapon, you spend time attached to your opponent, quite physically. There is a period of time where you can seek to influence them. This can even occur after the knife has gotten under their skin, but before it hits something truly fatal. A killing with a ranged weapon in that world would be barbarous. But with a knife, and great skill, a holy warrior with an official charge from their cardinals could go back and try to redeem Hitler himself. Perhaps a knife wrapped part way around his carotid artery, lifting it out from his skin without fully severing it, might be just the leverage needed to lead him to become born again. And if not, the knife works. As it always has. [Answer] **Short Answer: Because in an advanced environment where high tech could overkill and therefore melt the environment around a target, melee weapons offer an opportunity to handle close combat in close quarters, without damaging the surroundings. The very surroundings that may be protecting the people inside from vacuum or a hostile environment outside.** One real life example to look at that helps provide some perspective is modern day naval ships. The US Navy has surface to air missiles, cruise missiles, miniguns, torpedoes, and soon even railguns and lasers at their disposal. In addition to this, there are fleets of ships that could travel together, which would help to hinder or prevent the unlikely event of hostiles boarding the ships themselves. Yet modern naval vessels still carry a [sufficient armory of small arms](https://www.quora.com/Do-US-navy-ships-have-a-large-stock-of-firearms), including rifles, handguns, and shotguns. In the corridors of a ship, close combat is inevitable, and any form of melee weapon may be yet an additional useful tool for survival in combat. This can easily be applied to a space ship, where boarders could have weapons that could be capable of punching, exploding, or melting holes in the bulkheads. On something like a spaceship, this could be dangerous, especially near vital systems. Melee weapons could offer an alternative that allows the boarders and repelling forces battle without irreparably damaging the ship from within. As for training, military forces today still train with melee weapons and combat. All forms of martial arts are still practiced, although not necessarily for anything other than recreational or competitive purposes. Just as futuristic forces are trained in their futuristic, exotic weapons, they'll likely be trained to also use a knife and their own fists as well. [Answer] You have 2 types of long range weapons, unfortunately in your future they are not very effective against combat droids * Kinetic weapons: These weapon throw an object at high velocity (a bullet, a rocket, a missile) towards their enemy and try to do damage with their kinetic energy. The problem is that in the future, most robots/droids have hyper sensitive long range sensors and superhuman reaction time (like in matrix/men of steel). They can therefore quickly dodge incoming projectile fired upon them. On top of that they have super resistant and flexible armor making most them immune to most projectiles of reasonable size. They are also resistant to the blast from a larger missile. Of course you can still use fusion or antimatter bombs to flatten an entire area against robots but that is overkill and not strategically meaningful. * Directed Energy beams: These weapons focus a beam of energy on the enemy (laser, plasma etc...). The beam travels at the speed of light so robots cannot dodge them. However most robots are equipped with a magnetic force field which can easily deflect those energy beams. A very powerful laser won’t be deflected but the energy required to go through the force beam is orders of magnitude higher than what a force field needs to deflect it. Lasers that can pierce an energy beam are very costly in terms of resource to build and energy to fire. They are so big and heavy that they have to be stationary. These big lasers are meant to fire on larger enemies like spaceships. It's a waste to use such a laser weapon against simple infantry. Energy fields cannot deflect melee weapon. Being in close combat means that no matter how fast your reaction time is, if you are fighting against an equally fast combat droid, he will be able to hit you. So while ranged weapon are still used to slow down/do light damage to the enemy, in the end melee combat is how combat droid vs combat droid battles are won. [Answer] UK and many other developed countries have severe restrictions on firearms (which will likely extend to any ranged weaponry). Only military and special police units have combat firearms. Civilians are limited to sporting and hunting weapons, which require registration, fingerprinting, training, periodic psychological profiling & income source review, and membership in a registered club that is held accountable for its members. Ammunition is expensive, sold in small batches, and you have to return empty casings to get more. You can even require weapons to be stored in a government facility and "checked out" for limited amount of time. And if you are caught with unregistered firearm or ammo, you go to jail. Moreover, millimeter-wave radar can see concealed guns. The sound of gunshot and the energy signature of a blaster can be easily detected and triangulated, and flying drones respond in less than a minute to track all the suspects on the scene. So both criminals and private security companies have to rely on melee weapons. Once they develop bots, nothing changes. Moreover, as others said, bots can be shielded against small firearms and energy weapons, or can detect and dodge them (and report to authorities). But not armor will save you from a good old hammer swing. Even if the shell holds up, the innards and the limbs are damaged. [Answer] A [neutralization field](https://en.wikipedia.org/wiki/A_Lord_from_Planet_Earth#Neutralization_fields) was invented. It blocks **all weapons except for bladed one**: ranged, energy, even nuclear fission/fusion are blocked inside it. The same for matter/anti-matter reaction and other hi-tech. Because of complex equipment, it's not possible to create mobile field or create field which covers continent. But most important cities/locations (like capital or military base) are covered by this field. Goverment buildings, elite restaraunts also have their own field. By the way, it's once more reason for castles building. The idea borrowed from the storyline by Russian writer Lukyanenko. He described circumstances in very small fashion, maybe in couple pages. Main reasoning is `inside field any process which equal or more complex than 'powder explosion' are blocked`. As far as I know it hasn't published in English but avialable in Russian in many sites. [Answer] It's probably fallacious to think that all possible civilizations would inevitably develop similar technology. And if conditions are different, it's quite easy to think of ways that technology may advance far past us in one area, but stall in others. In our own world, it was the advent of firearms that signaled the fall of melee combat in warfare. So think of a way to prevent firearms. What if your world had no sulfur with which to make gunpowder? What if it had no metal with which to make barrels that could withstand the pressures of an explosion? If you can come up with any reason that firearms are hard to make, then you can easily justify melee combat even while this society becomes quite advanced. [Answer] Because, as you said, magic and technology don't go well with each other. Gunpowder is rent ineffective at the sole contact with any spell or magic user like other complex and delicate artificial products. What about the droids and computers? They are originally made with the help of magic that combines noble materials in a way that doesn't interact with magic. But some droids can replicate themselves and evolve to produce descendants without the use of magic. ]
[Question] [ In my story, an ancient building has been abandoned for a whole century without any care or use from the inhabitants around. They refrain from approaching it because they believe it is cursed, which is why it hasn't been scavenged for resources. The building is located near the sea on top of a hill, around 20 meters above sea level and 100 meters away from the coast. It doesn't get flooded but there is only grass surrounding it, nothing that would stop wind. The winters are mild, and the summers quite hot (mediterranean weather, I imagine it as north-west of greece in terms of temperature) Here's a brief description: The structure describes a large circle, whose floor is 4 meters (around 13 feet) under ground level, it has no roof, no windows and does not go above ground level (consider it as a well). It has a 40 meters diameter (~130 feet), the wall is entirely covered in stone held by mortar, while the floor is a mix of stone and large metallic shapes incrustations. Those shapes are made of copper. There is one stairway large enough for 4 men to walk side-by side, made of the same stones+mortar. It is not very steep and protuberates from the circle by a few meters. It connects to a dirt path. After a whole century, exposed to wind, rain, what would this building look like? [Answer] The biggest unknown factor here is what the quality of the stone and mortar is. Also, since you mentioned it never floods but is basically a big hole in the ground, there must be a drainage system which has not been clogged for a hundred years. I find this fact very hard to believe. Let's start with the most straight forward piece first, the copper inlays. These will undergo considerable corrosion due to the sea spray which is inevitably available given your location. [Here](https://www.omicsonline.org/open-access/corrosion-rate-of-copper-and-iron-in-seawater-based-on-resistance-measurement-1410-5217-5-127.pdf) is a paper to describe the damage salty water sprayed on copper can take. Since you exclude the possibility of fresh water filling your building thereby protecting your copper insets, your copper would be heavily corroded (how much depends on a huge number of factors). Secondly, a hundred years of debris (dead plants, animals, insects, etc) blowing detritus of all manner in to building will create quite a pit of nasty. Presumably the rain is washing this away and then draining somewhere without being clogged? This would be difficult without some rather large outlet holes in your floor (and it must be graded to allow the flow of water). On to the stones/mortar. If the building is limestone, it will be heavily eroded. If it is granite with modern (even Roman) quality hydraulic cement, there would be minimal erosion. Again, your ebb and flow of water going in to the building and then exiting is causing you more erosion here than if the building was filled with water. Also, any plant life which gains hold (depends on your construction) could cause mechanical destruction of the stones/mortar, allowing even more water in, which creates a cycle of damage. If you consider allowing it to flood as a plot device, it would be believable for the building to be filled with rain water (mostly non-salt water) and the dead organics have caused a blockage in the drainage system. The intrepid explorer who first visits it could clear the debris and allow the structure to drain, exposing quite possibly near-intact copper insets. After some cleaning of the rotten organic material (which would also include a layer of sludge on the bottom), it wouldn't be hard to believe that the structure could be mostly intact. [Answer] **It could last a very long time.** [![cistern on Delos](https://i.stack.imgur.com/HdDZ7.jpg)](https://i.stack.imgur.com/HdDZ7.jpg) <http://www.ancient-wisdom.com/greecedelos.htm> Delos is a Greek island, so a climate similar to or a little warmer than what you propose. This cistern is well over 1000 years old. I think the trick will be water - fresh water. A hill over the ocean is a good place to find a spring because erosion cuts through the various sedimentary layers. The spring keeps water in the bottom of your structure. The level will vary according to rainfall in the hills. The fresh water will keep the copper on the floor from oxidizing in the salt spray. The cistern is a little porous and will slowly drain if the spring slows down, and this will tend to carry windblown particulate debris away. The water level changes (as you can see in the image). Your "well" might be dry at some times of the year, if that helps your story. If there is a low wall surrounding the edge that will deflect larger things like blown weeds; the Delos site has a low wall which also keeps drunk people from falling in. The hilltop site means nothing is uphill that might roll down and in. Copper is toxic to plants, so standing fresh water containing copper ions from your floor inlays will discourage plant growth. Storms would hit your site, as is the case on Delos. The cistern is hunkered down below ground level and so protected, and has done a lot better over the centuries than the surrounding above ground structures. [Answer] Wind and rain will have easy access to your structure. Wind will blow dust and solid objects into it, including seeds. Rain will make the structure a swimming pool of mud, either wet or dry according to the season. The seeds carried by the wind will have an easy growth, shielded by the winds. Grass and other weeds will grow in the mortar, breaking it, allowing an even more efficient trapping of solid particles. Since the building is located in Mediterranean climate, it is likely that some bird will poop some seeds there, too. If these seeds happen to be from fig or capper, the structure is doomed: [![cappers on city walls](https://i.stack.imgur.com/GQMCf.jpg)](https://i.stack.imgur.com/GQMCf.jpg) the roots of those plants are not afraid of walls, and can grow into them. After 100 years most of the wall would be collapsed and filled with vegetation, the hole filled with dust carried from the wind and other biological remains. [Answer] Well, as AlexP said in the comment, your well would be half-buried under the rubble from the walls that cave in, and filled with plants and small bushes. But seeing its located just 100 meter from the coast, I think the most likely thing to happen is this: <https://en.wikipedia.org/wiki/Ruins_of_the_church_in_Trz%C4%99sacz> It took a little bit longer than a hundred years for the church to disintegrate, but then again it was a bit further away from the sea. In your case, I would think that there might be something like half of the well left (and it won't be a well anymore), if anything - but that's up to you, as it is you that's writing the story. [Answer] **Does it freeze?** In these mild winters, does it occasionally freeze? If so, depending on material, weathering can go a *lot* faster, especially when combined with a lot of rain. Concrete and mortar can act like a sponge, soaking up water, which expands when it freezes and lead to cracks in the material. Even a little night frost can cause a little pointing to come off, exposing just a little more surface for next year's night frost and so forth and so on. Over time the process can turn the entire structure to dust, again depended on the materials used. This picture shows the effect of (pretty mild) winters on mortar made with lime over the course of a decade or so [![enter image description here](https://i.stack.imgur.com/GEpks.gif)](https://i.stack.imgur.com/GEpks.gif) Without maintenance, this wall would probably be a pile of rubble in a 100 years. ]
[Question] [ On a [comment to *My carrier pigeons have been replaced by spoons: how can I send messages?*](https://worldbuilding.stackexchange.com/questions/120828/my-carrier-pigeons-have-been-replaced-by-spoons-how-can-i-send-messages#comment372778_120828) I joke about creating a network of trebuchets to launch spoons. Is it realistic? My concerns: * How far will it be launched? * Would the spoon resist the impact? * Is a trebuchet accurate enough? * Is it affordable for a medieval king? I will first make a single route of 25km. (No industrialization or Chinese factories in my universe.) * What would be the speed of this message? [Answer] So a few things first; Spoons are not very heavy. Spoons are not aerodynamic. A trebuchet is great when you want to throw a 90kg stone over 300 meters. You could potentially throw a lighter load further, but it takes a bit of juggling to get maximum distance. The more mass something has the harder it is to get moving, but once moving are harder to stop, which is why most trebuchets sending very heavy messages used enemy castle walls as backstops. A smaller load is easier to get moving, but will be affected by air resistance and wind more. The dimensions of the trebuchet are also a huge factor. The length of the arm, the counterweight mass, the counterweight drop distance, the projectile mass, pivot height... Just going bigger does not guarantee better real world results. The average spoon weighs [around 25 g](https://en.wikiversity.org/wiki/Average_weight_of_a_conventional_teaspoon_made_of_metal), and due to the thin convex shape would be more susceptible to drag than a more sphereical object such as a ball or rock. You can use the [Virtual Trebuchet](http://www.virtualtrebuchet.com/#simulator_%24id=003&LengthArmShort=1.2&LengthArmLong=5.9&LengthSling=4&LengthWeight=1.7&HeightOfPivot=3.2&MassWeight=250&MassProjectile=1&MassArm=25&ReleaseAngle=45&uniformArm=false&ProjectileDiameter=0.300&InertiaArm=52.08&PivotToArmCG=1&InertiaWeight=1.1&CalculateDrag=true&WindSpeed=0&projectile=custom&customProjectile=true&units=metric&advancedMode=true&playSpeed=1&customPlaySpeed=0.15&length=m&mass=kg&angle=deg&velocity=m%2Fs&inertia=kg%C2%B7m%C2%B2&time=s&=&distance=158.3278841158951) to design a trebuchet that can throw a light object, but getting more than 300 meters is hard, and that's assuming a spherical object, not a spoon. If you start plugging numbers into the VT, you'll see that there is diminishing returns when it comes to weight. A 1kg object will travel further than a .5kg object. Increasing the mass of the counterweight can help some, as can increasing the lengths of the arms, but each has diminishing returns as well. Getting an actual distance of more than 300 meters might be possible if you were throwing a spherical spoon in a frictionless vacuum, but real world results will not be as good. Accuracy will also not be great, especially if there is wind. If there is any kind of underbrush or long grass then finding a single wayward spoon is going to be difficult. But because it is so light it should slow down enough before hitting the ground to resist the impact just fine. [Answer] ## Range Trebuchet ranges [vary quite a lot](https://en.wikipedia.org/wiki/Trebuchet#Comparison_of_different_artillery_weapons), from a bit under 100 meters to as far as 300-400 meters. "Siege crossbows" could have ranges of 500-1000 meters. Therefore, I think ~500 meters is a reasonable target. Today, [Warwick Castle's trebuchet](https://en.wikipedia.org/wiki/Warwick_Castle#The_Warwick_trebuchet) can hurl a 13 kg projectile 250 meters at 190 kph. If you were to redesign it to throw a lighter object - like a spoon - those numbers would increase dramatically. ## Cost [Alexios I](https://en.wikipedia.org/wiki/Alexios_I_Komnenos) is [thought to have had trebuchets, or similar weapons](https://en.wikipedia.org/wiki/Trebuchet#Counterweight_trebuchet), and they were certainly used in the 13th century. Now, keep in mind a couple things: * Alexios was an emperor and was fairly powerful. * His empire was at war, and war means more funds diverted to . . . war. * Alexios liked inventing new weapons. Therefore, for a rich, war-like emperor, this is a more plausible scenario, especially if these trebuchets have military applications (and they do - they're trebuchets, after all). ## Theoretical speed and range I used [this trebuchet calculator](http://homepages.umflint.edu/%7Eaahancoc/trebuchet/) to get some results. Though I was limited by the calculator itself, I used the following parameters: * Counterweight arm length: 10.5 ft (3.2 m) * Projectile arm length: 10.5 ft (3.2 m) * Counterweight mass: 98.5 lbs (44.7 kg) * Projectile mass: 0.5 lbs (0.23 kg) The resulting speed was 2381 ft/s (726 m/s), and the range was 176881 feet (53.9 km). I suspect the stresses here would be too much for the machine, so I toned things down to a counterweight mass of 49.5 lbs (22.5 kg). The result was a speed of 1182 ft/s (360 m/s) and a range of 43425 feet (13.2 km). This means you'd only need two trebuchets to travel the full 25 km distance . . . assuming that the spoon survived. Which I doubt it would. 1182 ft/s is a lot for a poor spoon. There are some things this simulator ignores, however, and tweaking the parameters a bit leads to different results. I also considered [a different trebuchet calculator](http://www.virtualtrebuchet.com/) that takes into account the mass and moment of inertia of the arm itself. Here are some of the parameters I used: * Length of long and short arms: 10.5 ft (3.2 m) * Mass of arm: 10 lbs (4.54 kg) * Mass of counterweight: 98.5 lb (44.7 kg) * Mass of projectile: .055 lb (24.9 g) * Projectile diameter: 0.1 ft (3 cm) This yielded a distance of 166 ft (50.6 m!) and an initial speed of 88 ft/s (26.8 m/s). Why? Well, it takes into account friction and the mass of the arm itself. Now, if we increase the projectile mass to 0.55 lbs (0.249 kg), we can get a distance of 232 ft (70.7 m). As some people have suggested, these calculations might be a bit off because the calculators weren't designed to be used for throwing light, non-spherical objects like spoons! They should be more accurate if we use heavier projectiles - which could mean placing a spoon inside a more durable shell. The shell could also protect it a little during landing. Regardless, we know that trebuchets can chuck things several hundred meters, and if you're willing to strap a spoon onto one of those projectiles, those ranges can be achieved. # Time [theGarz pointed out](https://worldbuilding.stackexchange.com/a/120859/627) that reloading and resetting a trebuchet can take a while. I agree that the distance (25 km) could be covered in a very short time; 1.5 to 2 hours is reasonable for a good runner. For the trebuchet to be an efficient mode of communication, you would need to have the turnaround time be very quick, and you'd need the accuracy to be good. Hunting in the woods for a projectile that's gone astray isn't easy. Looking for a spoon in a forest is probably worse than looking for a needle in a haystack. It's debatable as to how much of an improvement a horse would be over 25 km; [30-50 km in a day might be a reasonable estimate for a horse's stamina](https://worldbuilding.stackexchange.com/a/6414/627) unless it specifically trains for this sort of messenger work. Nonetheless, a sort of [Pony Express](https://en.wikipedia.org/wiki/Pony_Express) might also be a good option - and more efficient that a trebuchet unless the trebuchet's turnaround time is short. [Answer] Not really realistic... > > How far will it be launched? Would the spoon resist the impact? > > > 300m at maximum with a proper projectile, while the spoon could resist the impact you should put it inside a more aerodynamic shape. Your king would be one of the first users of [message encapsulation](https://en.wikipedia.org/wiki/Encapsulation_(networking)). > > Is trebuchet accurate enough? > > > It has a reasonable accuracy, I guess 30m at maximum, it was used to aim at specific buildings inside a besieged castle. The trebuchet operators (Gynours) doesn't need to spend a lot of time fetching the launched message. > > Is it affordable for a medieval king? > > > A very rich one can reasonably afford a hundred trebuchet, covering no more than 30km, enough for your first test. Sieges with 20-30 trebuchet were big sieges, still real sieges. NB: just because you can doesn't mean you should, trebuchet are really expensive. > > What would be the speed of this message? > > > If the operators are ready to receive and resend the message you could estimate 3-5 min for every step (with preloaded machines ready to launch). 5 hours at least. Why would you spend this much money on machines and operators to carry a message in 5h at no more than 30km? Running on feet have more or less the same speed. A couple of mounted postmen will do the job in a fraction of the cost and time. [Answer] How about semaphore stations? Smoke signals? Those seem like better choices. Modern semaphores might not be period-accurate, but based on some reading I did, the Greeks used "hydraulic semaphores", and the earliest one was developed in 4th-century BC Greece. A clever emperor should be able to devise a visual signaling system using stations at line-of-sight distances. ]
[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/114098/edit). Closed 5 years ago. [Improve this question](/posts/114098/edit) So, at many colleges in the North American region, most famously the New Jerusalem University and Chicago Collegium, much old world, pre-apocalyptic information is often taught at schools, including the electron and electricity. Old electrical engineering books and warning labels translated to New English is what college kids are taught from. But there is a huge feud going on in the academic community about the electron and electricity. Believers, called “electricians”, say that many pre-apocalyptic books and other materials cite the electron and electricity as real, concrete facts. They also claim that technology of the old world was impossible without electricity. Doubters, called “anti-electricians”, say that it is highly plausible that old time books were mistranslated, and that besides the books, they have no real proof of the electron. The also say that it is possible that Old world technology was powered by some other source, possibly witchcraft, and that teachings of the electron should be taken out of school. So, here is my question: How could the believers plausibly prove to the doubters that electrons and electricity are real? [Answer] Electricity is easy. Shuffle-shuffle-touch-OW! That's electricity, baby... Proving the electron is a bit more complicated, but borrowing from [this question and its answer](https://physics.stackexchange.com/questions/299612/how-to-prove-the-existence-of-the-electron) from our sister site, physics.SE, we find the [Millikan Oil Drop experiement](https://en.wikipedia.org/wiki/Oil_drop_experiment). Basically, oil droplets were allowed to fall between two metal plates with an electric field (thousands of volts, don't try this at home) between them. The result is that as the voltage was changed, the particles would move up and down. The result of the analysis is the ability to mathematically and empirically determine the charge of an electron. Which you can only do if it exists, of course. *Rubbing a baloon on your head is more fun, though. So is rubbing a cat with a glass rod and touching your friend. Proving the existence of electricity is so trivial that it's hard to believe the existence of the argument — unless they don't have access to electricity and don't want to follow in Ben Franklin's footsteps with a kite, a key, and a convenient thunderstorm.* [Answer] ### Competing theories As other people have pointed out, electrical phenomena are so commonplace it would be irrational for a scholar to ignore what a piece of fur and a glass stick can show you. Proving that electrical phenomena are the result of the mutual attraction or repulsion of tiny, indivisible charged particles is a much harder endeavor; it would probably take more than one experiment to convince the 'anti-electricians' that electrons are real. Furthermore, you might still be skeptical that electrical phenomena are powerful enough to have powered the machines of the past. Here's how I would do it, given a weekend with a room full of doubters, and a prepared laboratory full of 1700-1800 tech: ### 1) Two Types of Charges Using a variety of triboelectric materials (fur and glass rod, plastic and felt, etc.) I would then take turns transferring the charge (by touch) to some suspended metal spheres: [![electrostatics1](https://i.stack.imgur.com/3wnOv.png)](https://i.stack.imgur.com/3wnOv.png) If we take the fur and glass rod as an example, there are three possibilities: 1. I touch the fur to both metal spheres independently. In this case the two spheres repel. 2. I touch the glass to both metal spheres independently. In this case they still repel. 3. I touch the glass to one sphere and the fur to the other. In this case they attract. From this, and repeating the experiment for different materials, I make the hypothesis there are are only two types of charges, and similar charges repel while opposites attract. Note this says nothing about charges being discrete; I have yet to show that the presence of 'positive' and 'negative' charge isn't fluid-like (i.e. it's a continuous substance with no 'smallest amount'). ### 2) Crooke's Tube After demonstrating the rubbing of glass on fur or felt and plastic can separate charges, I would demonstrate a machine that takes that process and repeats it continuously: [![wimhurst machine](https://i.stack.imgur.com/p9JqO.jpg)](https://i.stack.imgur.com/p9JqO.jpg) The Wimhurst machine depicted above is a hand-powered, high-voltage generator. A Van de Graaff generator would also prove sufficient for this purpose. After repeating the same experiments as in part 1), I would then connect the generator to a partially evacuated glass tube with a single metal surface on the inside as shown: [![crookes tube](https://i.stack.imgur.com/LrnVw.jpg)](https://i.stack.imgur.com/LrnVw.jpg) The metal plate, called the *cathode*, is present in the back of the tube, while the second metal connector is placed elsewhere (the bottom in this case). The cross in this picture is electrically isolated. When the generator is cranked, *cathode rays* emanate and project a shadow. The presence of the shadow clearly indicates that *something* is leaving the cathode, traveling in straight lines, and striking the wall of the tube. This helps confirm that when there is indeed a transfer of some sort of electric material during electric phenomena, as opposed to being imbued with an 'electric property'. As a bonus, placing an electrically charged sphere next to the tube will deflect the cathode rays, confirming their electric nature. ### 3) Millikan Oil Drop Experiment Once you have demonstrated that only two charges exist, and that an actual substance is responsible for electricity, the nail in the coffin is of course the oil drop experiment performed by Harvey Fletcher and Robert Millikan in 1906. I think the experiment could have been performed with earlier technology; perhaps in this society the necessary parts could be scavenged instead of manufactured. Here is a diagram of the experiment: [![oil_drop](https://i.stack.imgur.com/ehbWK.png)](https://i.stack.imgur.com/ehbWK.png) This is a *statistical experiment*: as oil droplets enter into the chamber, they receive a small net electric charge. By varying the charge applied to the plates, you should be able to apply the correct electric attractive force to suspend the small oil drop against the pull of gravity. This allows you to calculate the suspending force from the plates. What Fletcher and Millikan noted was that the force is always some **integer multiple**. That indicates that the amount of charge present is **discrete**, which the fluidic / aetheric models of electricity cannot account for. With a bit more math and a calculation of the mass of the oil droplet, you can work out the charge on the electron. Although that is not strictly necessary if all you care about is showing the discrete nature of the electric charge. [Answer] I will point out that in today's electrical engineering we pretty much *do* this. Albeit not with the neo-luddite trappings. We generally think in terms of volts and amperes flowing from the positive to the negative, and never about the electrons\* - that's physicist territory. And why not? Most of the time the fiddling small details of electrons don't matter in electronics. To demonstrate the existence of electrons you need to prove they're practically useful to have as part of your world model. For this you want to call in the chemists, who deal with electrons in a more direct fashion. A few rounds of demonstration starting with the famous lemon battery should suffice: different metals and electrolytes will have different results that can be predicted based on their valency, ultimately reconstructing a car battery from first principles. The reason we want a chemist is because we want someone qualified to *predict* what happens when we arbitrarily vary the conditions. This then becomes the foundation of our proof: if electrons didn't exist, we wouldn't be able to predict what happens with different substances based on the properties of their electrons (amongst others). Since we can, we can disprove the non-existence of electrons. \*This is called 'Conventional Current'. In reality the electrons flow from negative to positive but it has the same result so nobody cares. [Answer] # Van de Graaff generator Take [a glass rod and a piece of silk](https://physics.stackexchange.com/q/23515/56299), or a piece of amber and some fur (arguably the better post-apocalyptic choice). Rub the two together vigorously for perhaps 10 or 20 seconds - I've found 10 is often enough. Congratulations! You've transferred charge. More importantly, you can do things with this charge. It's not hard to make a tabletop [Van de Graaff generator](https://en.wikipedia.org/wiki/Van_de_Graaff_generator) ([here's one in action](https://www.youtube.com/watch?v=3jwgWI6P-Xc)), which uses a similar mechanism to transfer charge to a metal sphere. If you take a second metal sphere and hold it close enough . . . you get a spark! It's quite a dramatic demonstration, even on a small scale. [![enter image description here](https://i.stack.imgur.com/ey0KA.jpg)](https://i.stack.imgur.com/ey0KA.jpg) A small Van de Graaff generator. Image courtesy of Wikipedia user Lefrancq under [the Creative Commons Attribution-Share Alike 3.0 Unported license](https://creativecommons.org/licenses/by-sa/3.0/deed.en). Going back to the amber and fur (which, by the way, might be mentioned in one of those apocryphal books), it's clear that something has to be transferred, right - some sort of charge. That's where the electron comes in. Define an electron as simply a particle that carries charge - or even just say that it's a little bit of charge. The small sparks that you can generate should convince people that there is indeed such an object. # Helmholtz coils Another possibility - one I like even better - involves using [Helmholtz coils](https://en.wikipedia.org/wiki/Helmholtz_coil). Helmholtz coils are pairs of circular bunches of wire, each bunch having a large number of loops, separated by a distance on the order of the diameter of the wires. When a current is passed through the wires, a simple magnetic field is created between the coils, which is uniform midway between the two. If you fill a chamber with the right kind of gas - I've used helium - and find a way to eject electrons into the chamber at the right angle, placing the chamber inside the coils, the electrons will follow a circular path, colliding and exciting helium atoms, making them emit light. It's pretty dramatic. The only issue, of course, is that Helmholtz coils are powered by electricity, which you clearly don't have. Therefore, if you can either power the coils by hand somehow (unlikely) or generate a uniform magnetic field from one or more permanent magnets, this can work - and it will probably convince the doubters even more, since they can see the path of the electrons. Here's what the apparatus looks like, from the side: [![enter image description here](https://i.stack.imgur.com/SPyCd.png)](https://i.stack.imgur.com/SPyCd.png) Image from my a lab manual at my college. Image credit Adam Light. --- It's been argued that these experiments merely show that there exists some substance or fluid with electric charge. It's not hard to construct an argument that there must be some small components of that fluid - after all, [you can make the same argument for atoms via Brownian motion](https://en.wikipedia.org/wiki/Robert_Brown_(botanist,_born_1773)#Brownian_motion) using nothing more than a minimal microscope. If normal fluids are made up of small particles, why shouldn't this "electrical fluid"? [Answer] Showing that there is a force, and it can be harnessed to do useful work, is easy. You just need a bog-standard dynamo with a crank, an electric motor, and some wires to connect them. Even if you don't have batteries to store power, this rig will let you demonstrate that motive force is being transferred in some form that's clearly not mechanical (the wiring doesn't move, and wouldn't be large or strong enough to carry that much force even if it did). That doesn't prove any of the other properties of the electron, or that it's what the ancients based their technology on, but it's clear evidence of *something* happening. [Answer] # Batteries! Batteries were the first reliable source of electricity, and perhaps date back to [ancient times](https://en.wikipedia.org/wiki/Baghdad_Battery). You can with some effort, generate a stack of plates to produce a substantial voltage, enough for an arc. Proof of electricity follows simply from using wires to conduct your charge to wherever you want. Proof of the *electron* is more difficult. Historically electricity was viewed by some as a fluid. As pointed out above, chemistry is a good way to show that there is something integral going on since reactions occur in stoichiometric proportions. Again, the Millikan oil drop experiment was the first clean demonstration of the quantized nature of charge. [Answer] Thomson's experiments established the identity of electrons: > > He found that the mass-to-charge ratio was over a thousand times lower than that of a hydrogen ion (H+), suggesting either that the particles were very light and/or very highly charged. Significantly, the rays from every cathode yielded the same mass-to-charge ratio. This is in contrast to anode rays (now known to arise from positive ions emitted by the anode), where the mass-to-charge ratio varies from anode-to-anode. > > > The existence of cathode and anode rays, along with the material-independence of cathode rays proves there's some charge carrier common to all materials used. <https://en.wikipedia.org/wiki/J._J._Thomson#Measurement_of_mass-to-charge_ratio> To build up the hard vacuum needed for cathode rays, you'll need some glassware and mercury. <https://en.wikipedia.org/wiki/Sprengel_pump> <https://en.wikipedia.org/wiki/McLeod_gauge> To power the apparatus we'll want reliable power, with major options being electrolytic cells and your choice of generator. So far we need: * a good deal of copper drawn into wires; * glassblowing (making narrow-bore capillary glass may be a challenge); * metallic mercury; and * an electrical power source, most likely one of: + metals and concentrated acid for battery chemistry or + magnets, frame, and bearing for a dynamo. What, you want precision measurement, too? Of course you do. For expediency, I'll just point out that it's possible, if not common, to boostrap your way with precision surfaces. <https://en.wikipedia.org/wiki/Surface_plate#History> Thus far, the outside materials we need were more or less known by the medieval period. We should also call for some abrasives - maybe we luck out and can get low-grade sapphire. More modern steelmaking processes would also be nice, and we might end up asking for refined platinum or tungsten as part of tooling and our vacuum tubes. As an alternative to isolating electrons themselves, we could focus on crude semiconductors. With wire, galena, and a very fine-point conductor (we probably need high-quality steel here), we can start work on RF experiments, AM, and a detector. I'm not sure where to put this, but with a rectifier we can more assuredly get the Thomson experiments working since any generator design would be usable as a DC source. It's as good as done if you can isolate, say, cadmium and selenium. <https://en.wikipedia.org/wiki/Metal_rectifier> Incidentally, you would very likely need to remove all electrical artifacts and if not all human memory to 'lose' awareness of electrons as real entities. ]
[Question] [ **This question already has answers here**: [0g pool: can I keep a big ball of water in space?](/questions/54633/0g-pool-can-i-keep-a-big-ball-of-water-in-space) (13 answers) Closed 6 years ago. Man is on board of a spaceship with enabled artificial gravity swimming in a pool. Due to a malfunction gravity goes out. Pool liquid tends to form a sphere with the man locked inside. * Will it still be possible to swim out of the bubble given a weightlessness? * As for artificial gravity mechanism I would suggest two options: + There is some kind of gravity field, which could be turned on and off almost immediately. + There is more conventional *spinning gravity* that fill fail smoothly. **P.S.** Situation plot is taken from a sci-fi movie Passengers (2016). [![enter image description here](https://i.stack.imgur.com/jtxRE.jpg)](https://i.stack.imgur.com/jtxRE.jpg) **Video:** <https://youtu.be/IOVrvZ3aKt4> **P.P.S.** There is a similar question answered at WB: [0g pool: can I keep a big ball of water in space?](https://worldbuilding.stackexchange.com/questions/54633/0g-pool-can-i-keep-a-big-ball-of-water-in-space) Still would like to keep a separate one, because it more focused on surviving a gravity failure while in a pool than the mechanics of a zero-g pool itself. [Answer] Surface tension will try to keep the water together, but it will retain (of course!) all of its inertia, so several things will happen: * The large mass of water (like that on a swimming pool will break up due to inertia locally (think: "ripples") overcoming the force due to surface tension. * Each mass will stick to any "wettable" surface it encounters. * The swimmer can give a hard stroke to get rid of the large mass of water he is swimming into and sail straight towards the ceiling. * His action will produce large ripples in the pool and a large number of smaller masses will detach and start floating around. * Masses touching each other will try to merge, but this will produce waves on the surface and smaller masses may be expelled. * The swimmer has a chance to use the environment strategically to propel himself through the door before the swimming pool is filled by so many "water bubbles" it may become difficult to breathe. * At equilibrium (after all kinetic energy is "consumed" by friction) water will cover any wettable body (including the swimmer) it can reach and stick to it. [Answer] Removing gravity will remove the buoyancy on the poor swimmer. The surface tension of water will make it flow all around him/her and also inside his/her nose and lungs. Basically the swimmer will be sucked into the mass of water by the surface tension, and according to his/her apnea skills he/she can survive up to few minutes before drowning if he/she doesn't manage to reach a solid grip and exit the bubble. Moving inside a bubble is doable (basically it is just underwater swimming), the issue is breaking the water film to get out of it, as there will be no gravity assisting the effort (insect drinking from water droplets have to hold firmly on a surface to not be sucked into the droplet, same would apply here). In the scene you link the swimmer would not be able to poke her head out of the bubble and breath as she does there. See [this video](https://www.youtube.com/watch?v=o8TssbmY-GM) for reference of what happens when you squeeze a wet cloth on ISS. After the first moments the water will then start to expand by wetting all wettable surfaces. If the swimmer has managed to exit the bubble he/she better run for the exit and have it sealed. Else a thin film of water is going to cover the entire ship interiors, with easily imaginable consequences on electronic and mechanical devices. [Answer] One should theoretically be able to swim in water within a zero-g environment, seeing as how the fish involved in the Medaka study aboard the ISS were able to swim without gravity. The swimmer can still push the water in order to propel themselves in a zero-g environment, just like they would if they were swimming in an environment with gravity. (link to video of fish swimming <http://iss.jaxa.jp/library/video/medaka_suisoutounyuujinoyousu.html>) [Answer] (Clearly none of you have passed your starfleet pool safety training course, so you will not be allowed in the pool and therefore will not die) Although the death and mayhem described by others provides a better story here is what will happen. (Starfleet of course will have rules, regulations, and advanced safety gear.) (Protocol demands at least triple (3 levels) redundancy for every system.) Emergency teleports will activate and beam the people to safety. If you have a ship that advanced the safety computers are going to be hay we are going to loose gravity, start draining the pools NOW! They will need pumps to suck it out, but drains all sides of the pool meaning whatever direction the water goes in those drains will open. The pools will have independent gravity field generates for this very emergency. In the Star Trek world you be trained and it would be in your safety procedures guide padd(manual). There will be redundant sensors all over the pool to detect a massive increase in pressure on any side of the pool. Once detected, drains will open up and allow all the water to be evacuated. The drains, of course, will have safety measures like grates and etc to prevent people from being sucked in. In the end a bunch of people, who were once swimming will be on the bottom or against a side of the pool wondering what happened. Sure accidents are possible, and some will get injured. Every once and a while someone will die. Most likely the medical staff will be able to evacuate the water from the people lungs and CPR them. Addenum: We will probably have rebreathers that can suck the oxygen from the water and/or people will have to carry small tanks of oxygen to provide enough air to survive a full evacuation of water plus a safety margin. There will be safety drills just like we have fire,tornado, or etc. Which will prepare people for this very type of thing. You will have to pass ## (whatever is approved by regulation of starfleet command) of drills with trained life guards before you can go in alone. [Answer] If you switch off an artificial gravity field on a swimming pool without changing the speed or orientation of the ship the changes are going to be slow to build up and might afford time to escape, probably not though. The first thing is that the water is going to suck the swimmer in if they're not already below water, no gravity, no buoyancy. Secondly the water is going to start to flow out around the room across any surface it comes in contact with. Both these effects are due to the liquid surface tension. If a swimmer can stay conscious while the water flows out to coat the inside of the room and the room has sufficient surface area then the swimmer may be able to then use a wall to get enough leverage to escape the pull of the water and affect an escape. Unless you slow it very very gradually switching off spin gravity on a pool will result in water going everywhere as it maintains its momentum while the ship stops moving around it, anyone caught up in that is likely going to get pummeled to death long before they drown. This agitated mass of water is going to spray droplets off into the room for a long time and it's going to keep moving until air resistance and surface friction strip in of all it's kinetic energy, it's going to be like being in a washing machine on spray-rinse. There is however a possible advantage to a lucky swimmer who doesn't get killed early in that the very chaos of the event means that they're less likely to be stuck in any single significant volume of water; they won't need to hold their breath all the time just be ready to dodge the large droplets on their way to the door. Both scenarios are complicated by the fact that the water will not all stay together. The artificial gravity situation will see blobs and bubbles of water separate from the main mass of liquid and move independently around the room until they stick to something, unless the water is perfectly and completely at rest when the gravity goes down, and even then the swimmer breaking free will liberate a lot of droplets. A spin gravity shutdown is likely to impart so much relative velocity to the water that it turns into a chaotic foam of such bubbles for a short interval before they shed enough momentum to start sticking instead of splashing when they hit. Once the water settles on to the walls, if it's still reasonably deep, the surface tension will make wading around the walls somewhat comparable to walking under gravity in that you'll stick to the surface instead of bouncing off into the room, if you're careful anyway. It will however require considerable strength to open any doors coated in water and considerable momentum to punch through the curtain of water that initially covers the door. Also you'll want to shut the door fast once you're out because the water is going to want to spread itself across every surface in the ship to a uniform depth. ]
[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/57858/edit). Closed 7 years ago. [Improve this question](/posts/57858/edit) The enemy is approximately 100 million in number and are closing in fast from the orbit of Uranus, at a constant speed of 70 km/s (in near perfect vacuum condition). They are like clones and each one is the size of a mini Cooper made almost entirely of carbon nanotubes (displacement of 3,141Kg with full propellant). They act as a swarm, similar to a shoal of fish, but more delicate and graceful. Smaller swarms may branch off to attack high value targets like our communication facility or supply network, then merge seamlessly with the main swarm. Their propulsion appears to be some sort of advanced ablative casimir matter-antimatter warp drive hybrid(specific impulse of est. 80,000s). It seems they only rely on their rigid structure to penetrate our defenses, they have no other weapons, no force shield, no bio signature, and strangely no known communication among themselves! At least based on our existing model of physics that is. Their purpose is to exterminate (indiscriminately) all intelligent carbon based lifeforms in the Milky Way galaxy. Their movement is directly proportional to their surface temperature, the hotter they are up to a maximum temperature of 3500℃ their speed can clock up to a maximum of 80km/s for a couple of minutes in empty space. They never rest until their battery runs flat! aside from the flying in disciplined phalanxes thing during search and destroy, they do not seems to have any kind of strategy at all. Using existing 21st century technology, how could we prevent our own extinction by such a mysterious and formidable foe? [Answer] Swarm and flock members follow very simple rules that let them maneuver in concert with the others. They use the perceived rate of change in speed and orientation of their most immediate neighbors. <http://www.red3d.com/cwr/boids/> If the aliens adopt such a pattern of flight, it's a strong indication that they follow similar rules, with comparable inputs. The best way of disrupting or redirecting the swarm (into the Sun?) would then be to exploit this behavior. 1) Find out how the aliens perceive their immediate neighbors (sight, electromagnetism, etc.). 2) Engineer devices that can mess with these signals (holograms, movable magnetic fields, etc.). 3) Use them to take control of the swarm or to turn it against itself. [Answer] All of the workable defense strategies I've read thus far assume the space bees are in a tightly packed formation. There is no particular reason for this to be the case, and since they are not idiots I am going to assume they spread themselves over the maximum volume possible. A relatively small sacrifice in delta V will result in very large fleet dispersals meaning that no nuclear weapon will be able to kill more than a single bee, and clouds of dust or sand will not be large or dense enough to materially affect the fleet during transit. The OP says the fully fueled mass of the bees is 3141kg. Using this online calculator <http://www.strout.net/info/science/delta-v/> an 80,000 ISP, and 70,000 m/s delta V suggests an unfueled mass of 2870 kg. That gives me a 7E12 joule energy. (i.e. 7 terajoule or 1.6 KT) The total energy of the fleet will be 7E20 joules or 170,000 MT. The bolide which killed off the dinosaurs is estimated to have had 130,000,000 MT of energy, so the bees would have almost 1,000 times less energy if they all get through our defenses. This handy calculator gives you the effects of an individual impactor. <http://impact.ese.ic.ac.uk/cgi-bin/crater.cgi?dist=.001&diam=2.76&pdens=261&pdens_select=0&vel=70&theta=90&tdens=2500&tdens_select=0> projectile diameter is 2.76m, density is 261 kg/m^3, velocity is 70 km/s, angle is 90 degrees. The one problem it has is that it assumes an impactor tensile strength of a natural material, whereas these impactors are made from carbon nanotubes. I don't know how to calculate how atmospheric frictional heat loadings affect the material, nor what kinds of tensile stresses result from the atmospheric traversal, but I think it is safe to say the impactors would penetrate to a lower altitude than indicated in this calculator. But since the calculator has the impactor detonating into a fireball at 121,000 meters altitude, I think it's very unlikely that it would reach a low enough altitude to markedly affect the surface before it detonated into a fireball. The other noteworthy takewaway from this calculator is that the fireball energy is only 1/7th the kinetic energy of the impactor. (Presumably the rest is lost to friction prior to this point.) This puts the attack in a very different light. Essentially all of the energy of a fleet attack which was well distributed across one half of the Earth would go toward heating the atmosphere, producing little or no effects on the ground other than loud noises and bright flashes of light. In order to produce any truly dangerous effect, the attack would have to be focused. If the bees fire a dense stream of impactors at selected targets, they can produce deeper penetrations. The initial impactors would produce a partially evacuated shockwave in their wake, through which the following bees could travel with less energy lost to the atmosphere as friction, resulting in lower detonation altitudes (possibly not detonating until impacting with the surface). Also, the thermal flash effects would be concentrated in one area, resulting in arbitrarily high thermal loads in that vicinity. Potential strategic impact sites might include the Yellowstone super volcano (possibly requiring the entire fleet to cause any likely volcanic effect here?), nuclear reactors, flash heating attacks on drought afflicted forests in order to cause massive firestorms and nuclear winter effects (nuclear winters rely entirely on sending smoke into the stratosphere via a firestorm), flash heating of crop lands in order to create famine conditions, bioweapon research labs (human diseases are pretty bad, but just as horrible would be the effects of uncontrolled release of novel crop diseases), and oil refining and storage facilities (cripples our economy and contributes smoke to stratosphere). One problem with focused attacks is that they make it easier for the Earth to degrade the attack (with nuclear detonations in space and sand cloud attacks). The goal would be to degrade the nanotube structures to make them break up higher in the atmosphere. The higher the altitude at which the impactor breaks up in a fireball, the less the damage to the surface. I think the bees would be smarter to invest in larger and denser but fewer impactors. Carbon nanotubes might be good material for the outer skin (I'm not sure) but the impactors should carry a payload of natural (non-explosive) uranium, tungsten, or other extremely dense material. The impactors should be shaped like arrows, not like pods. They need to lose as little energy as possible on atmospheric friction, and density is the key to this. The impactors should come in a variety of sizes. Small impactors for nuclear power plants and ICBM silos. A super large impactor for Yellowstone and other super volcanos. If I were the aliens, I would generally ignore the cities and concentrate on killing the populace via secondary effects such as climate change, famine, infrastructure collapse, radiation contamination, and disease. But to answer your exact question: The way to protect the Earth from a dispersed attack is probably to do nothing. The way to protect from a focused attack is probably, like people have said, nuclear missiles and clouds of sand focused on points in space where the bees are converging. [Answer] # What are we dealing with? Given that there are hundreds of millions of them, and they are made of carbon nanotubes, most projectiles aren't going to work, and because they are already at Uranus we do not have much time to prepare: at a minimum they are 2.6 billion km away, or 429.9 days away (max speed, min distance) And at a maximum they are 3.15 billion km away or 520.8 days away (min speed, max distance) The time taken varies so much because it depends on how far Uranus is from the sun, and whether earth is on the same side or the opposite, which means we have over a year to prepare, and a year is how long it takes to build a nuke if you have the fissile materials already, so we would start building as many nukes as possible. # Problems with the swarm These things are travelling at 70km/s and are the size of a mini cooper, which is about 1.55M high, 4.01M long and 1.79M wide, which gives a total volume of about 11.126m^3, and if that is pure carbon nanotubes, which have a density of 1.6g per cm^3, then each robot in the swarm is about 17.6 tonnes... so if one were to impact the earth, it would have 1/2 \* m \* v^2 = 83,300,000,000,000,000 Joules of energy... This is a ridiculous amount of energy: the most powerful nuke (tzar bomb) has about 100 mega-tonnes (built not tested), or about 418 petajoules, whereas one swarm robot has 83.3 petajoules... over a fifth of the energy of the most powerful nuke ever built and there aren't that many nukes available to have the same energy output as the swarm. # Conclusion / Tl;Dr One swarm robot hits the earth and we all die, tsunamis and magnitude 10 earthquakes will happen, maybe some arctic researchers will live, but that is about it, this swarm is near unstoppable on kinetic energy alone and does not need any weapons of any form to be well beyond our capacity to deal with. # Maximum potential of the swarm This is the absolutely everything goes wrong scenario, where all of the swarm is at 80km/s and all 100 million of them hit the earth at once, you have 10,880,000,000 **petajoules** of energy. The sun outputs 384,593,280,000 petajoules of energy... meaning our swarm's kinetic energy is greater than 2.5% of the power output of **THE SUN** in one second. ... I have checked these calculations many times and have made many adjustments, but I think this is finally correct, if these are wrong I no longer care, do your own research and compile your own answer. [Answer] Simple. Just nuke them with everything we've got. It should be enough to destroy them. Since they absorb energy to speed up, but have maximum speeds and temperatures, we can nuke them enough so that they are overloaded and damaged, or destroyed. Plus they might be vunerable to the EMP from nukes, causing some internal malfunction or disruption to their propulsion. A quick google showed me an estimate of 23,000 warheads in the Earths nuclear arsenal, with an estimated yield of 6400MT, in 2009. That's a yield of 64 tons of TNT per alien, less due to losses of course but if the bombs can all be detonated at the center of the swarm (and remember they may ignore our silicon-based warheads since they are out to destroy carbon-based life forms), then quite a lot of that energy will hit aliens (no estimate on swarm density was provided). Any amount of tons of TNT is still quite a lot of energy to dump on a device the size of a mini cooper, even if its made out of high tech materials. Each alien device can suck in energy to accelerate to a maximum of 80kms (why this, there are no arbitrary limits on speed in space, nor constant speeds either for that matter). The term "ablative" and the maximum temperature stated suggests to me that the engine will take damage when pushed beyond its max capacity. Lets look at the energy needed to do that. Assuming an alien bee is made up of solid carbon nanotubes, this'll give it a mass of approx 11tons (based on 1.6g per cm^3) from the comments. To accelerate that by 10kms requires 131tons of tnt per alien, about double the yield of our nuclear detonations, so the aliens should be able to suck it all up and accelerate without incurring damage. However, if an alien is half hollow, this explosion will push it to its max acceleration. If the alien is a hollow shell of nanotubes around some small core, like a carbon fiber mini cooper chassis with an engine, then it will have a gigantic surplus of energy to deal with. Perhaps it has heatsinks to deal with some overload, but we can see from these numbers that todays nuclear arsenal is powerful enough to provide a *major* issue for the aliens. Now, assume that this scenario is set a few decades in the future, and our nuclear arsenal has doubled in strength. This is enough to impose damage on the whole alien swarm. Should we have developed even more powerful weapons in the next few decades then the potential to overload the aliens starts to look quite likely. With Uranus being about 2.6billion kilometers away and the aliens traveling at a constant 70kms in a straight line towards us (despite space travel not working remotely like this), that's still a minimum of 14 months for us to prepare. Real orbital mechanics would only add to this figure. I'm pretty sure we could increase the size of our nuclear arsenal several times over in that time if our survival as a species depended on it, bringing vaporization of the alien fleet well within our capability. And this is ignoring any kinds of secondary explosions or effects due to dying aliens. A chain reaction of explosions may develop. edit: as rightly pointed out, many nuclear missles are not capable of getting to orbit. But orbit is nor required here. Most missiles are intercontinental, which is a range of thousands of kilometers. Shooting them straight up to intercept the swarm is still possible. Summary: depending on the aliens density, our weapons technology development in the near future, and what happens when the alien bees are pushed to accelerating beyond their max speed, we can detonate enough nukes to destroy them. [Answer] While beyond current capabilities, the only practical defense is to use their immense kinetic energy against them. Much like a satellite in Earth orbit could be disabled by impacting a small piece of space debris (even a leftover bolt or paint fleck in a different orbit), impact with space debris is going to do immense amounts of damage to the swarm. Looking at the math in other answers, individual units of the swarm already have kinetic energy measured in Terra to Petta Joules. Even hitting a stationary grain of sand would vapourize the incoming unit of the swarm, so the answer is essentially dump buckets of sand in the path of the oncoming swarm. Now since it takes years for current spacecraft to reach the outer Solar system, you can see that getting warheads into position (especially in the numbers needed) is far beyond any near term or even projected capabilities of Earth. Even SpaceX does not have the assembly line capabilities to build boosters to launch hundreds of thousands of interceptors into LEO, so short answer is "we're doomed". However, handwaving the problem for a moment, or assuming some friendly alien gave us a heads up with a few decades to prepare, our space armada could meet them with the following items: Using fuelling depots in orbits around Mars and Jupiter, even conventionally chemical fuelled spacecraft could reach deep space in reasonable (months to years, rather than decades) amounts of time. This is the [ITS](http://www.projectrho.com/public_html/rocket/realdesigns2.php#spacexits) proposal that Elon Musk has raised, although in this case, we are sending missile busses. Each warhead is fitted out with a nuclear "shotgun" shell, based on the SDI "[Prometheus](http://www.projectrho.com/public_html/rocket/spacegunconvent.php)" project. Using a clever arrangement to direct the explosive energy of a nuclear device against a pre scored plate (much like a hand grenade), pellets can be accelerated to a velocity of up to 100 km/sec. > > Up to 5 percent of the energy of a small nuclear device reportedly can be converted into kinetic energy of a plate, presumably by employing some combination of explosive wave-shaping and "gun-barrel" design, and produce velocities of 100 kilometers per second and beam angles of 10-3 radians\*. (The Chamita test of 17 August 1985, reportedly accelerated a 1-kilogram tungsten/molybdenum plate to 70 kilometers per second.† ) If one chooses to power 10 beams by a single explosion, engaging targets at a range of 2,000 kilometers with a kill energy of 40 kilojoules per pellet (one pellet per square meter), then such a device would require an 8-kiloton explosive and could tolerate random accelerations in the target, such as a maneuvering RV or satellite, of up to 0.5 g (5 m/s2) > > > The initial plate for each beam in this Casaba-like device would weigh only 32 kilograms but would have to fractionate into tiny particles to be an effective weapon—4 million evenly spaced pellets to produce one per square meter at 2,000 kilometers range. If such pellets could be created uniformly, which is highly questionable, then, at a velocity of 100 kilometers per second, they would each weigh 8 milligrams, carry 40 kilojoules of energy (the amount of energy in 10 grams of high explosive), and travel 2,000 kilometers in 20 seconds. Such hypervelocity fragments could easily punch through and vaporize a thin metal plate and could cause structural damage in large soft targets such as satellites and space-based sensors, but they would have little probability of striking a smaller RV, or even disabling it if a collision did occur. > > > While pretty impressive against Earthly technology, the real purpose here is to ensure a rapid spread of pellets into the path of the swarm. Since the swarm units are moving so much faster than the pellets, they provide the kinetic energy and on impact there should be enough Ke to vapourize the unit, and indeed any units nearby in a rapidly expanding fireball. Earth is saved! ....or is it? The huge calculated energy of the incoming swarm is being released into high energy fireballs by the collisions with the pellets of the "Prometheus" warheads. Carbon atoms are being accelerated to incredible velocities (at the energies being discussed, we are possibly talking about nucleons and electrons moving at near light speed), and the effect of these carbon atoms moving at such high velocities is discussed in the obligatory XKCD comics [here](https://what-if.xkcd.com/1/) and [here](https://what-if.xkcd.com/20/). The entire Solar system could be swept clean of life by the wave of high energy radiation being released by the stopping of the swarm. Perhaps the best bet is to get out the thumb and [hitch a ride](https://www.youtube.com/watch?v=BtqXLwNj2RE) out of here instead [Answer] The only solution to an improbably dangerous superior threat is improbable odds. Secondary requirements to their mission might limit them in ways that give us a chance. Ok, the aliens are here to kill intelligent carbon based lifeforms. So we know that counts as humans, and possibly a few other species on our planet. **If they care about not completely destroying the ecosystem** ...that reduces some of their attack options - they can't send too many crash-bombers into the planet or everything gets wrecked from ensuing dustcloud winter. Likewise, they can't just swarm above the planet to reduce sunlight until we all freeze to death (if they don't care about taking a bit of time to do the job). Which are basically the two overwhelming options they have. This means they have to go slower, and while they can wreck critical infrastructure as the quickest way to kill the most people (food, water, electricity, etc.), the rest takes longer as they have to find and hunt down the rest. This buys humanity some time. **If it is important that the swarm as a whole survive** ...even if they sacrifice many individual units, then you have a chance to scare them off, at high cost, without necessarily having to destroy the whole swarm. **If we can develop a countermeasure in time...** So let's say we can figure out what they're made of and have time to develop something to work against them. There's a small but dedicated worldwide group of people who keep a look out for potential objects to impact Earth - once folks see a massive swarm of small objects on an intercept course, we're going to turn a whole lot of telescopes that way (we have risky, untested plans for dealing with a large object, but not so much with a lot of small ones so it will get a lot of attention presuming we can see it in time). Even before we get good visuals, we'll probably be able to pick up that they're nearly entirely carbon by spectography. IF we can figure out they're not natural, IF we have someone theorize they're actually carbon nano-tubes or similar materials, IF we figure out they're probably hostile, IF we start weaponizing our current technology of [enzymes that break down carbon nanotubes](http://newatlas.com/enzyme-breaks-down-carbon-nanotubes-in-the-body-14771/14771/), we might have a way of doing some damage. However, again, if the aliens care about preserving the rest of the ecosystem mostly, we get a lot more time to work with. How to deliver these enzymes? Given that the aliens move ridiculously faster than even our newest railgun technology, it's less about targeting them than blanketing as much of the atmosphere with these enzymes - which means modifying bacteria to produce these enzymes and letting them fill as much of our airspace as we can. Presumably these aliens survive slamming through tiny micrometeors in space, so I doubt the breakdown of general surface damage will do much, but once the enzymes hit the lower layers, the whole unit might come apart as it travels through the atmosphere. At high speeds, that's going to be messy. At lower speeds, the units might simply disassemble. If the anti-matter sections are built of different material and fail-safe instead of fail-dangerous, humanity gets a tech boost out of the whole affair. Otherwise we get a bunch of antimatter explosions. Crud. **Now what?** Again, assuming the swarm cares to survive, here's possibilities: * Swarm members who haven't entered the atmosphere, will not for fear of contamination. If they have some kind of means of communicating back home, the planet is marked "contaminated" and either left alone or a different, more horrific weapon is sent (over the course of centuries or longer travel time). If they don't have a means of communicating that far, maybe they send a few to fly back, and the rest monitor the infected planet. * If they all have entered the atmosphere (to speed up the hunt), then they're all potentially infected with the bacteria, and may attempt to leave some kind of warning to future aliens to not come here. Perhaps some kind of massive last strike to carve up part of a continent with a symbol or sign. Or they get back to orbit and smash that sign into the far side of the moon. However, that's a whole LOT of if's to get here. Given that the aliens don't have FTL travel, they would probably just have the drones slam the planet or sunblock it to either a) kill for the sake of destroying potential future rivals or b) by the time they come around for colonization proper the ecosystem has recovered/evolved. [Answer] # No, Mr. Human, I expect you to die. TLDR: you can't defend the Earth, a 'relatively' stationary, known target. In warfare this is known as 'unprepared ground': current technology does not have much defense against a single 'killer asteroid', nevermind a hundred million of them. Note that even summing all active, reserve and paramilitary forces on Earth, [you don't get to a 100M number](https://en.wikipedia.org/wiki/List_of_countries_by_number_of_military_and_paramilitary_personnel), so assuming the bees are so kind as to fight hand-to-hand, we'd still be vastly outnumbered and out-gunned (since they are the equivalent of miniature tanks). There are alternative strategies, though, with correspondingly devastating losses. # Play Dead, Convincingly Humans can't really nuke a swarm of asteroids: they lack the rocket lift capacity, and even with a year to develop it, lack the ability to maneuver warheads in such a way it could reliably destroy enough aliens with each precious warhead to stop an invasion cold. On the other hand, we have plenty of capacity to nuke ourselves. And, moreover, it would only take one nuclear-capable country to kick off the party. Humans can burrow down, build bunkers and shelters and other ways of hiding - probably as distributed and as difficult to detect as possible. Once you get a sizable (5%?) of the population in such a situation you start WWIII. From the bee's point of view, this is a bit of a [Seige of Masada](https://en.wikipedia.org/wiki/Siege_of_Masada), but they then have the choice of how much energy they're going to spend digging through a nuclear wasteland to determine if there are any survivors. (This is assuming, of course, that they don't just rain down destruction from above, in which case any defense is moot). Presumably, at some point, it will be diminishing returns for them to keep searching and they move on. (If they are never going to move on, again this is a moot point.) You could hold off on the war until the bees were in atmo, so as to take a few with you. Also, while it would be dodgy, building deep underwater might make it difficult for the bees to come after and/or detect the bunkers, depending on specifically how they propel themselves and do detection. Or it might make it easier for them to compromise bunkers if underwater operations are no problem. # Run Assuming the swarm is staying relatively close together and immense resources were capable of being managed (which is a practical blocker to this plan - retooling the economy will not be easy), a handful of space craft could be built that might, possibly, maintain human life against the vagaries of the void. Build as many as you can, and a whole bunch of dummy or suicide life boats (with a handful of human sacrifices onboard to make it convincing). The real ones should be launched in a trajectory that puts the Earth between them and the bees, so as to best conceal the retreat. The others in all directions, including into the swarm (to see how they react, and what weapons might exist). Maybe pop off a few nukes or other distracting things in order to make it appear that Earth is going to put up a fight and draw attention from the escaping humans. A variant on this plan include an out-and-back trip for humans to come back to Earth after, presumably, the bees have left. [Answer] Each one has kinetic energy of about 2.4 terajoules. Since there are a hundred million of them, the total energy is about 240 exajoules. A megaton is 4 petajoules, so the total available energy is about 60,000 megatons. That's 300 Krakatoas or ten times the Earth's entire current nuclear arsenal. I don't think we can defend against that with 21st century technology. [Answer] You have a little under 2 years to prepare. Get as many ships as possible spaceworthy (old shuttles, new drones, ICBMs, etc...) and load a nuke and carbon lifeforms into each. Launch them early and send them as fast as possible towards the swarm. Don't shoot them, let the swarm converge and overwhelm, and blow all nukes at once when they are in the radius. Meanwhile on Earth, get all military on the planet to deploy as many ground to air and space based defenses (railguns, flak, missiles, etc...) as possible, and decentralize your entire control structure, so that you are not automatically KO if they disrupt satellite communications. Prepare a global ground based targeting network and plug it into the decentralized control. You can also launch a lot of dirt, sand, gravel, scrap metal, etc from space. It will form a wide, almost invisible cloud of debris slowly moving toward the fast moving swarm. A single shovel of dirt impacting a drone at 50KM/s is probably enough to destroy it and create more debris, destroying more drones, starting a chain reaction. Then just wait. Hopefully the nukes will destroy a large portion of the swarm from the direct blast. Since carbon nanotubes will either act as a metal or semiconductor depending on nanogeometry, there is a very good chance that your "solid" CNT drones **are their own brain**, with the outer layer of the hull acting as a kind of nerve termination network, carrying information to the core, the protected "thinking" brain. If that is the case, a whole range of energy weapons will EASILY disrupt them, and the EMP from a nearby nuke will very likely knock them "unconscious", if not kill them instantly. The dirt cloud will help break down more, and hopefully your ground to air and space-based defenses will be able to intercept what remains, or at least enough that you can avoid extinction. Hope for the best. This will let you defend from an attack, but your only chance at long term survival is to figure out how to rewrite their core protocols, otherwise more drones will come. Capture a minimally damaged drone, somehow, and reverse engineer it like your life depended on it (it does). [Answer] Send spaceships with sacrificial humans to divert them. How far do swarms break off? If not astronomically far, it's plausible that the whole swarm will divert to kill a lone astronaut or a small group. We can take advantage of that and send many suicide missions, engineered to keep them running around. Our best minds can abuse slingshot maneuvers to have the ships divert the bees from other ships multiple times. This may well be sustainable, i.e., we may be able to do this forever, launching new ships to replace the ones taken and the ones that run out of supplies, with enough redundancy and flexibility to absorb contingencies. And how smart is "intelligent"? We might be able to make do with monkeys and dolphins. [Answer] Short version: Simple. Send out a single nuke to one of them. Make sure that there is no direct line of sight to earth. Done. --- Having no weapons means they absolutely have no defense against nukes. A nuke reaches 10^6 C. No material can withstand that temperature. Definitely no carbon nanotube can stop that explosion. Nuke will disintegrate first couple of bees, which contain antimatter which would be left without a container. This will spew extreme amounts of damage in X-ray, which would probably disintegrate even more bees. This will continue until there are no bees left in the swarm. If there is a line of sight to earth that might be enough to permanently change the life on earth. It won't be enough to make humans go extinct. --- Even if previous method doesn't work, humans will survive. I don't think they can carry enough antimatter (I know how much power they hold) for the task. Rooting humans out of earth requires them to destroy earth. Nothing short of that would cut it. ]
[Question] [ So Earth has just suffered a horrible catastrophe and most of civilization is back in a Middle Ages level of development. A few people live on other planets relatively unscathed, with highly advanced technology (But nothing inconceivable. No teleporters, no going faster than the speed of light, and computing never got past basic optical processors, so it's only a few orders of magnitude faster than the current fastest supercomputer.) They have decided not to try to let people on Earth gain technology because they are afraid that they will lack the ability to use it right. Unfortunately, the climate is completely unsustainable and requires maintenance to prevent it from spinning completely out of control. Like CO2 levels at brinkpoint, weird changes in climate, etc. Their solution is to put a refinery on the planet where they use large amounts of energy (they have large amounts of energy) to collect CO2, CH4, and other atmospheric pollutants and re-release harmless O2 and H2O. However, I can't think of a way to put this on Earth's surface without allowing the inhabitants to know. I would like not to have to set aside an entire continent. My first idea was radiation (covering only the boundary / the plant is automated and can handle radiation), but that has a tendency to spread. I was wondering if there was any way to create a barrier that would prevent middle age-level technologically advanced people from entering. (I'm thinking they have no gunpowder, no animals (all killed off in disaster), and little wood because of the climate's effect on forests. So not that much of a threat, just don't want them snooping around and getting advanced technology.) [Answer] For the conditions you've given (medieval technology, little to no wood, and no animals) people will really need to stay put. There isn't going to be much exploring. Without game to hunt, travellers would need to rely on carried food or foraging. Travellers will also be walking. Using this information it's not difficult to guess [places already inaccessible](https://en.wikipedia.org/wiki/Extreme_points_of_Earth#Remoteness) to these humans. You could start by looking at places humans in our own history were not able to get to with medieval technology. Places that were not explored until recently in our history or even now remain mostly unexplored. For instance: **[The southern pole of inaccessibility](http://en.wikipedia.org/wiki/Pole_of_inaccessibility#Southern_pole_of_inaccessibility)**. Antarctica wasn't even landed on until the early 19th century and the pole wasn't reached for another 100 years. Building a station at the pole, especially one disguised as a pile of snow, is unlikely to be discovered. Without wood for ships or dogs to pull sleds, even if people were able to land on Antarctica, they're not going to *walk* to the pole. **Under the ocean.** Perhaps at the [oceanic pole of inaccessibility](https://en.wikipedia.org/wiki/Pole_of_inaccessibility#Oceanic_pole_of_inaccessibility), or at the center of the Atlantic ocean, though that seems like the likely place for fish to congregate. Under water may not initially seem like the best place for an atmospheric refinery, but only the bulk needs to be under water. With floating air transfer stations the entire facility could be disguised as nothing more than a patch of seaweed. Assuming anyone ever even comes directly across it, which is highly unlikely, they likely won't be able to investigate much. Especially considering the minimal sailing that would be going on with so little wood for ships or energy dense animal meats for distant voyages. **Mt. Everest**. Just lop the peak off and replace it with the station of a similar shape. People of medieval technology won't likely reach the summit. The only reason this might backfire is because the station is *belching oxygen*, removing the requirement for tanks. For all of these options it's most likely that if they were found, it could be by a small group of intrepid explorers or a lost ship at sea. In that case build in some minor automated defenses to the station. Groups of people going missing while doing crazy things will not raise any eyebrows. In fact, **put it in the Bermuda Triangle**. It could be that *we* were the ones thrown back to medieval age technology, the rest destroyed, and the Bermuda legend arose because the off-worlders hadn't yet removed their ancient air processing equipment that brought our Earth back from the brink of being uninhabitable. Alternatively **spread it over the entire globe in the form of nanobots**. This will increase the surface area for processing and will remain hidden from medieval tech due to their nanoscale size. [Answer] > > Their solution is to put a refinery on the planet where they use large amounts of energy (they have large amounts of energy) to collect CO2, CH4, and other atmospheric pollutants and re-release harmless O2 and H2O. > > > This isn't really feasible. Atmospheres are mind-boggling huge. Earth's atmosphere weighs roughly 5.5 quadrillion tons. Say you can process 1 billion tons of air an hour with your refinery, which I think is wildly optimistic. That refinery will take 627,854 years to fix everything *if you never process the same air twice*. Realistically it will take even longer. A better solution that also helps with your "how do I hide this" problem is to think organic. Instead of creating mechanical factories, why don't you make plants that do that processing for you? Think about genetically engineered algae, grass, or trees that clean pollutants as part of their natural lifecycle. Because these will grow and spread across the entire planet they will end up processing far more than any mechanical solution. And you don't need to worry about hiding them - you can even make them desirable, maybe they also provide food. Then your low-tech people will help spread the plants for you. [Answer] I would simply put them (you would want more than one, possibly many more) in the middle of an ocean. The Pacific and the Atlantic have plenty of space a medieval society would not really miss. The air processors would reasonably cause local weather similar to a permanent thunder storm with simply their waste heat. The storms would make ships naturally avoid the areas, hide the processor from distance, make it unlikely anyone seeing the processor would ever return home, and make any expedition to investigate the strange castle with 100 meter walls rumored by superstitious sailors almost certain failure. [Answer] What if the processing plants were in blimps or a more advanced versions thereof. The water they create could be exuded as a vapor, creating a cloud cover to hide them from view. They could travel to any hot spots that need immediate treatment, and could also be sent to areas suffering drought to provide additional water. The blimps could even become part of the people's mythology; the Cloud Gods that appear when the air gets thick or the ground gets dry. [Answer] You might start by creating a superstition, and back it up by a setup consisting of motion detectors and infrasound. The motion detectors would help in activating the infrasound only when people are approaching, thus allowing the local fauna to exist undisturbed. You could let it work on animals, too, if you like, since seeing that even animals avoid the region might even strengthen your superstition. On the downside, it could be a cause of curiosity. According to [Wikipedia](http://en.wikipedia.org/wiki/Infrasound), Infrasound will inflict all kinds of bad feelings, and might even cause ghost sightings. This should make sure anyone doubting the superstition and trying to see for themselves should be scared off. If necessary, a second line of defense might be an actual weapons array, making sure anyone making it through the infrasound barrier does not return to tell the story. Combined with the scarcity of ressources and the resulting scarcity of explorers (they would be busy surviving most of the time) this should provide the secrecy you are looking for. [Answer] I disagree with the Everest answer--people have climbed Everest without oxygen. You can't spend long in the death zone but some people can go there. Likewise, while Antarctica wasn't explored at that tech level I don't believe it's inherently inaccessible to that tech level. Nobody went there because they had no reason to go to the extreme effort, not because it was impossible. Instead, I suggest an environment too hazardous to be approached at the tech level. Take a volcanic island (Hawaii, perhaps??), beef up the volcano and redirect the lava. Your atmosphere plant is on the mountain, there's a moat of lava around the mountain. (The moat is lined with something that won't melt at lava heat and is enough of an insulator that the rock on the other side won't reach the melting point.) Lava keeps pouring from the volcano into the moat, it keeps spilling over the side in once place or another and then cooling. The tech level you give can't cross a lava lake, the tremendous winds the plant will generate (in order to pull enough air through it to do the job it's going to be moving a **lot** of air) make balloons a suicide mission. Even if they knew there was something interesting they can't get there. [Answer] The ocean is big. Like, really big. It takes up 2/3rds of the surface of the planet, and excluding coastlines and the occasional island, there is absolutely nothing useful out there, especially to low-tech people. Sure, there were groups of explorers that sailed across the ocean, but the earliest explorers stuck fairly close to the coast, and later explorers aimed for a fairly straight shop across. It may seem like an intrepid explorer may be able to see a factory out in the middle of the ocean, but actual chances of that are slim if you take into account what is actually visible; the curvature of the earth hides more than you might expect, especially if all you have is a spyglass on a ship. Use the Pythagorean theorem to determine the maximum view distance of a sailing vessel: $h^2 = d^2 + r^2$ (or $d = \sqrt{h^2 - r^2}$, to solve for visual distance), where $h$ is the height of the vessel plus the radius of the earth, $d$ is the maximum visual distance, and $r$ is the radius of the earth. The [radius of the Earth](http://en.wikipedia.org/wiki/Earth_radius) is about 3959 miles at sea level, at the equator; if a ship mast was 120 feet tall, a sailor with perfect conditions would be able to see an obvious object that is nearly level with the horizon at about 13.4 miles. Average ocean wave height is [about 17 feet high](http://www.srh.weather.gov/jetstream/ocean/waves.htm), which hides just about anything under that height. Basic camouflage (no shiny surfaces, water-colored exterior) would further hide anything. Weather created by the rushing wind would hide it as well, and would also create some weird weather patterns - patterns that a ship would be likely to avoid, or risk being capsized. Of course, if there were only one factory, it would be a circle with a one hundred mile radius to be able to have any sort of effect on the atmosphere. As large as the ocean is, it makes sense to have not one, but dozens, or even hundreds of air purifying machines, floating all over the world. 1,000 air-purifying factories, each with a one mile diameter, could be placed around the Earth, and programmed to move with the tides but stay at least 200 miles away from any coastline. They could communicate, as well, to make sure that 'hot spots' were well covered, and that they were well placed across the planet. It would be almost impossible for any ship to ever find them. And, even if one were discovered, it would be noted as a huge storm over a strange hole in the ocean, hardly something superstitious sailors would ever want to go near. As an added bonus for a smaller size, if a ship does get within a certain distance - say, 5 miles - the machine could simply close itself up and sink below the waves. Even if a ship came to investigate, they would never find it. As soon as the ship moves away (or it moves itself), it could rise and begin recycling again. Finally, if one did fail, it could simply float its way to a charted deep hole and sink to the bottom, where no one would ever find it. [Answer] You could just make it out of adamantium or some other space-age indestructible material and let the natives do whatever they want with it. They can walk right up to it, bang on it with clubs or axes, but nothing they do will even scratch the surface. After a couple generations people won't even notice it any more. Medieval people got around. Vikings, south pacific islanders, and many other groups crossed huge amounts of ocean. Nepalese have been climbing the highest mountains since long before modern climbing techniques. If you think about it, humanity started somewhere in the general area of Africa, and spread across the globe. There is literally nowhere that your factory will be safe from people, especially if they know it exists. Another option is biological and wide spread. Super trees and plants, but then you have to deal with human caused deforestation and how to spread the plants, especially if a lot of the planet is arid or not plant friendly in some other way. The last option is simply fear. "We don't go into that place, because the monsters hunt anyone that does. No one returns!" Fear will work more effectivly than walls a lot of the time, and for the people that are brave, you have an army of mutant spider robot attack squid to make sure they don't come back out. The only real drawback to this is really big armies. If some king really wants your factory, and can get together a large enough army, then they might be able to overcome your giant killer super space hamsters by numbers alone. [Answer] To take Loren's lava answer one step further, why not create or use existing human uninhabitable places to place your machines? The volcanoes are a great example of this. You have the energy, all you need to do is put the machines inside volcanoes, perhaps even using the natural volcanic emissions as part of the process. Further, rather than processing the air by pulling it in, fixing it, then emitting it, why not simply emit catalysts and the chemicals necessary to cause those reactions in the atmosphere? To consider volume, note that we altered the ozone significantly over a matter of decades, but by changing what we put into the air the holes in the ozone repaired themselves in a matter of years. So spread these machines around the world, disguised as, or inside, volcanoes that are active enough, or appear active enough, that humans will avoid them. The smoke billowing out (chemicals you create) will appear natural, and you could build in a self destruct sequence that destroys the machinery and buries it under lava if the humans become too curious. Given the recent catastrophes and being tossed back into the stone or feudal age, they probably won't think it odd for volcanoes to show up in places where there previously was little or no tectonic activity. ]
[Question] [ Inspired by [Could laser (or other energy-bolt-shooting) guns ever practically replace regular guns with bullets?](https://worldbuilding.stackexchange.com/questions/6384/could-laser-or-other-energy-bolt-shooting-guns-ever-practically-replace-regula) As cool as the Star Trek stun gun/disintegrator is. I sometimes question the use of "one weapon with settings" in combat or policing situations. Now we have police that use guns and tasers. Do you guys ever wonder why they don't ask manufacturers to combine the two into one weapon? Somehow I find it hard to see a police officer pointing a gun / taser combo on a "disturbing the peace" call While a single weapon that is visibly a taser seems more safe pointing at people "disturbing the peace" Pointing a loaded gun / taser seems contradictory to gun training "point your weapon down when you don't intend to fire" Or look at it another way how would you feel if you were the "perp" disturbing the peace and an officer points a gun / taser at you? [Answer] I could see it being *very* easy to accidentally use one when you use the other. If you draw a gun at anyone, you must be ready to shoot them dead. That's the general rule given. If you draw a taser, you're ready to just put them down. I would feel very uncomfortable with having to point a gun at someone in order to use my tazer. The result would be more questioning of the police. By making the edge between lethal force and nonlethal force a little thinner, you would give skilled policemen more room to use nonlethal force. However, in the hands of less skilled policemen (every job has its skill ranks), it would be extremely dangerous and litigious. [Answer] The reason why a police officer points a gun at someone is because they **don't** want to kill them. It is usually meant to intimidate the suspect to comply, because deadly force will follow when they don't. Deadly force should\* be the last resort when the life of the officer or of another person is in danger. When taser and gun would be one item, the suspect wouldn't know if they are threatened with deadly or non-deadly force. Many would assume the latter, not realizing that only the gun-feature and not the taser-feature can be used in the given situation, and not comply. That would result in more casualties of deadly police force than before. Another risk is operator error. A police officer might try to stun someone, but accidentally press the wrong button and kill them instead. Such accidents can be prevented by having both weapons being separate items, preferably with controls which operate and feel very different. \*) in theory [Answer] I can almost guarantee the reason they are not combined today is because of the fear of pulling the 'wrong' trigger when facing a suspect. Police Officers are human too (at least the vast majority) and they make mistakes. Pulling a weapon on someone is still a very stressful part of the job. Right now the decision is made when they decide which weapon to pull. Not only could it be awful for the suspect if the officer fires the gun instead of the taser, but what about the opposite, the perp pulls a gun and the officer shoots the taser and they are too far away? The officer could be shot in the time it takes to readust. Now if they come up with a weapon that you dial the setting up, and default always goes back to 'stun', where it's just a matter of intensity this would be much more likely. [Answer] More a complement to other answers than an independent one. Both tasers and guns are relatively mature technology designed for utility. That means that they do not have lots of unnecessary weight or size. Since about the only part of substantial size guns and tasers have in common is the grip, which may contain ammunition or battery, there would be very little saving in the size or weight from combining them. This implies that if you want roughly similar performance the combined weapon would have weight that is near the combined weight of its two components. Same for size. This would be a serious usability issue. Exposing the taser to repeated shocks from gunfire at the firing range is unlikely to help reliability either. It is also cheaper to maintain two simple weapons than one complex. All in all unless you have significant synergy, having two simple specialized weapons is better than having one larger and more complex combined weapon. If we knew how to build a gun that uses "electro-shock" ammunition that only stuns at low (relatively silent) velocity, but penetrates tissue at higher velocities and is capable of adjusting the velocity... That might make sense. It would still be more complex and less reliable than current guns, but it might be good enough. [Answer] I was up late last night mulling this over as an easy way to make a lethal/non lethal situation. I know that it has to be a handgun configuration. A longarm is easier to make distinction because it could be set up like a M203. My first design was something like the cop derringer with double triggers. Tazer would be front triggers and the 2 shots of .357 would be the back trigger. Then you would have your standard sidearm for definitive lethal situations. Now add a flip cap pepper spray on the baton and your decisions are faster and easier to make. ]
[Question] [ I have a small modern nation that has many ideals rooted in the idea of community. Notions of civic duty, caring for neighbors, mandatory community service, mandatory voting etc. are the moral bedrock of the society. The creators of this nation wanted their citizens to be aware of the people surrounding them. The last thing they wanted was to have a society that was incredibly lonely, and isolated from each other. Essentially a situation that we see slowly rising in modern times. What type of city or town layout would help combat the atomization/loneliness of its people? Some Notes: 1. People need to be able to own their own house/property. Communal living spaces aren't an option. 2. The nation is located on fairly mountainous terrain. Think Yukon territory or southwest Alaska. 3. They are a modern society, and the country was built during modern times using modern equipment. Historical considerations for geography and survival aren't as important. 4. Free mental health services already exist. But if your closest neighbor is a long walk or drive away, people are less likely to interact with broader society consistently. So, city/town planning certainly matters. [Answer] # The root of loneliness is too many people. Loneliness in modern society is often more about being surrounded by too many people, not a lack of enough people. When you surround yourself with more people than you can know, it forces you to practice social isolation skills. You learn to walk past strangers without stopping to talk to them because you don't have enough time to get to know everyone. You learn to ignore people who need help, because there are too many of them to help. You learn that you need to always be on guard because the people around you have as little reason to care about you as you have to care about them. In small communities people don't develop these self-isolation skills because they have the time, resources, and consideration to spare. So, everyone gets to know each other. In smaller groups, introverts are less likely to retreat from society and extroverts are less likely to treat others as disposable. This makes meaningful and enduring relationships easier to foster which do far more to prevent loneliness than just being around people. It also discourages anti-social behaviors when you are forced to learn from a young age that you can't just wash your hands of a person and move on with your life. Less anti-social behavior means you have less to fear from strangers which means its safer to get to know people you don't already know. Counter intuitively, fewer people all builds up to having more and healthier human relationships. # Compartmentalize your township In modern society, you can't just force a town to stay small forever, but you can grow it in a way that it functions like a cluster of small towns instead of like a modern city. *Disclaimer: Some users have commented that the following style of urban planning would not be pleasant for them individually to live in. This is an unavoidable consequence of any urban planning scheme. Whenever you try to force a society to a be a certain way, no matter how good your intentions, the answer will always be someone's dystopia. The one and only goal here is to minimize loneliness; so, please don't leave any more comments about the other shortcomings of this solution. I am well aware of the tradeoffs that would have to be made to make this system work.* ### Smaller Schools The problems of modern loneliness often starts in schools. It used to be common that schools were smaller with only 1 class per grade level, and more grade levels under the same roof. Those 20-30 kids in your Kindergarten class would be the same 20-30 kids in your 1st-8th grade classes ... so good friendships would last and rivals were forced into the same space long enough to be forced to reconcile. Now, many schools have gotten so large that 80-90% of your class mates change every year as they shuffle around 100s of students per grade level. This teaches children that friends and rivals are temporary and that it is best not to care about either. ### Smaller Neighborhoods Every person has a certain nexus: an area of thier home town that they consider thier neighborhood. In a city or apartment complex, this means you are often sharing your nexus with 100s or even 1000s of people, and all of these nexuses overlap so you run into people from outside of your nexus in your space all the time. When your nexus becomes so big that most people are strangers, it means that you must develop a general since of mistrust of everyone you meet inside of your nexus in order to protect yourself. This mistrust is isolating because it means you can not just stop to get to know the people around you. Many suburban areas have actually solved this problem by dividing up townships into sub-divisions and cul-de-sacs. When you live in a cul-de-sac, you could live in a large town or city, but when you step out your front door, it is always going to be the same 5-10 families out mowing thier lawns, playing in the street, checking thier mail, etc. This breeds familiarity and trust making it feel safe enough to stop and get to know those around you. Sub-divisions help too because they become larger compartmentalized communities which are still small enough that you can form at least a familiarity with those you live around, even if you don't know them all. And more importantly, the physical barriers they form help shape the nexus of everyone around you reducing the number of strangers you have to interact with, even if there are the same number of people within any given distance from you. If true suburban living is not an option for everyone, apartment complexes can be similarly arranged. Keep the complexes small and compartmentalized. Maybe 50-100 units per complex arranged around a central courtyard, and small communal spaces in every walkway so that each group of 6-10 units has somewhere "out-front" to hang out with the neighbors. That way even if you must live in a more physically crowded space, you still get the small town experience. ### Decentralized commercial/industrial zones Most cities naturally develop a central business district. A place where businesses like to centralize to synergize off of the attractive power of nearby businesses. At first it starts off simple. An office opens up, then a restaurant opens up next to it to feed the office workers lunch, then a gas station next to that to refuel the people going in to work, and it just snowballs after that until you have clusters of 100 story buildings packed so densely with commerce that people can only even access it through inconvenient public transit systems which are again over crowded, scary, and full of strangers which discourages trust and relationship building. Instead, if your town has many small commercial zones interspaced by your subdivisions, then no one place would become so built up as to attract the preference of 10s or 100s of thousands of consumers all flocking to the same relatively tiny part of town. [![enter image description here](https://i.stack.imgur.com/wHvBh.png)](https://i.stack.imgur.com/wHvBh.png) *The above diagram is only meant to be conceptual. In execution, the exact ratios of houses : cul-de-sacs : subdivisions : communities may be very different, and probably won't be layed out in perfectly symmetrical circles like this... unless you want them to be. A more natural layout may look something more like Reno Nevada.* ### Finally: elemenatate housing that encourages living alone Everything so far has been about not pushing too many people together, that said, the most important factor in not feeling lonely is not being completely alone. The most lonely population of people today regardless of how thier town is laid out are those who live by themselves. Many people will choose to live alone when it is the most economically and socially viable choice they have, but then find themselves feeling trapped in that loneliness. The best way to solve for this through city planning is by restricting the construction of housing that makes it economically preferable to live alone. If your building codes require that all housing units must have at least 2 bedrooms, then single people would be forced to pay the same higher housing costs as family households. This would create an economic incentive for people who would otherwise choose to live alone, to instead choose to live with a room mate. Even if you could afford your own 2-bedroom house, you'd have that extra bedroom just sitting there burning a hole in your pocket; so, if life started feeling lonely, it would become a non-issue to just try to rent that extra bedroom out. ## Is this Science or Speculation? There is a lot of conflicting information. Some studies show only a weak correlation between suburban living and loneliness, whereas others show a very strong correlation. According to [This article](https://www.americansurveycenter.org/commentary/suburbs-are-not-less-social-than-cities/) which reviewed the data from the [May 2021 American Perspectives Survey report](https://www.americansurveycenter.org/download/may-2021-american-perspectives-survey/), people in suburbs are only 2% less lonely than people in denser urban areas. However, [according to this World Economic Forum report](https://www.weforum.org/agenda/2022/01/lonely-study-green-space-city/), overcrowding increases loneliness by up to 38%. The reason that these studies show such different results has to do with thier methodology. When you ask a person "are you a lonely person?", the problem becomes "compared to what?" A person who is lonely 5% of the time may give the exact same answer as someone who is lonely 25% of the time because that amount of loneliness is normalized to both of them. So, a 1-time survey like the first one used above can't really be trusted to report loneliness; only people's perception of what normal amounts of loneliness is. The second study above was based off of [ecological momentary assessments](https://en.wikipedia.org/wiki/Experience_sampling_method) which randomly asked people how they feel right now. This is different because it has nothing to do with if you think those feelings are normal, just if you are having them. This makes the methodologies in studies that show a strong correlation objectively better that those that show a weaker one. The study of loneliness in unban planning is also confounded by the fact that extremely high population densities can actually reduce loneliness too. In California for example, population density has driven up the price of housing so much that single people can usually not afford to live alone. So, while Californians experience a lot of the same community isolation as other densely populated places, [they have the 2nd lowest % of single person households in the US, well below average divorce rates, and tend to score well when it comes to combating loneliness](https://aginginplace.org/loneliest-states/). So, there is also evidence that says that "encouraging" people not to live alone is also effective. [Answer] Feelings of [loneliness](https://www.weforum.org/agenda/2022/01/lonely-study-green-space-city/#:%7E:text=We%20found%20that%20being%20in,ethnicity%2C%20education%20level%20and%20occupation.) arise for a variety of reasons, only some of which are physical. * Crowding increases loneliness. * Greenspace decreases it. Crowding forces you to develop a "thick skin." If you are in a crowd you cannot pay attention to the details of the lives of those around you, because it would quickly overwhelm you. So you build defenses against being intimate with people. And those tend to work on everybody. Greenspace is relaxing. And it spreads people out. And people who are relaxed tend not to be so on guard. So you meet people. Say you take your dog for a walk and meet somebody else walking their dog. Or you go hiking and meet another hiker. So arranging things such that people don't live in "rabbit warren" apartment blocks with many thousands of people all piled on each other is helpful. And lots of parks and walking paths and other similar things is also. However, a key quote from that link is this: > > In contrast, perceived social inclusivity – the feeling of being with people who share our values and make us feel welcome – was associated with a 21% decrease in loneliness. This suggests that it’s the quality of our social relationships that matter – rather than the amount of social contact we have. > > > That is, you will feel less lonely if you are in a community of people who share your values. Just a few examples of such communities (there are, of course, many more): * Religious groups * Community and volunteer groups such as The Shriners * Activity groups such as Scouting So what you want is cultural structure that encourages activities based around common values or common ideas. The type of group that works will depend on the local culture. For example, there is a group called [Four H.](https://en.wikipedia.org/wiki/4-H) The four H's are head, heart, hands, and health. It is primarily a rural-farm sort of thing. They do things like teaching children how to raise farm animals, or do bee keeping, or the basics of forestry. It won't work very well for people who live in typical mostly-pavement cities. But a modified version could certainly be arranged. After all, [Beverly Hills California](https://beverlyhills33.mytroop.us/) has a Boy Scout troop. [Answer] ## A city layout that is walkable. ### Suburbia is bad. Post WWII there has been broad experiment with car centric designs. They are bad. Economically, environmentally, and physical health are some of the easier to show problems with car centric cities and towns. Economically they are bad, many US communities are bankrupt because they can't afford maintenance of their roads, sewers and other infrastructure. Walkable regions bring in more tax revenue per area. Commuting by car has much higher environmental impact then walking. fast cars and pedestrians mixing mean people die. Some of cities have 1/3 the downtown as parking. Needing to drive to everywhere means people are at destinations or are in cars/trucks. Things leads to more smaller more fractured communities. The effort to be a part of any community is increased by the isolation of the car. ### Walkable cities are historical norm. Pre 1950 all cities were designed/evolved around people. People have changed and evolved cities over thousands of years. Therefor consider lessons of the past. A city layout such that it is easy for the majority to walk/cycle where they need to go. Shopping, school, work all common destinations should be withing walking and or bicycling distance. Streets and driving still exist, its just that people are first. Walking cycling and or public transit need to be viable options for the major majority. It can be demonstrated that people value walk ability via higher property values. Less driving more walking means more physical activity, generally a good thing for mental and physical health. Fewer people in isolating cars allows for more interactions. ### Description of layout. Grid like layouts with mixed commercial residential and compatible light industrial. Grid like layouts allow for easy routing of mass transit, people, cars etc. Streets should be designed for sub 25Km/h this keeps things safer, allows children to play on the streets. A very common pattern is four to six story buildings; ground floor day-to-day commercial, second floor occasional commercial, and upper floors residential. This makes it so there are always people around and most times of the day keeping it more lively. ## Conclusion While walkability may not directly address isolation, It provides much more opportunity to interact with others in a less hostile, more affluent setting then car centric cities. At the very least they are a concrete direction to take cities that have measurable benefits. [Answer] ## Factory town A small town that is dominated by a very large industrial plant is unlikely to have very many people badly isolated. The workforce is likely to have strong social connections. The actual layout could vary according to your needs; the factory or plant could be at the town outskirts (best), or by itself just down the main road. Note any fired employees *will* get lonely, as they'll lose a lot of their friends. The other factor is having plenty of (well attended) churches; social connectivity and church attendance go hand in hand. So: small town, churches in the middle, factory at one edge. [Answer] **Communal Areas** People own their properties. But the properties are built like apartment complexes or dormitories with communal areas and facilities. Bedrooms are separate. Kitchens and bathrooms are shared. There is a big dining table next to the kitchen to encourage everyone to eat together. There is a communal garden in the middle of the complex that everyone shares. Everyone uses the same kitchen, fridge, bathtub and toilet. Everyone pitches in to clean. If you clog the toilets you have to unclog it yourself or everyone else will know, and you will be Stinky McPooPooFace for the rest of your life. ]
[Question] [ The goal is to devise a plausible [geocentric](https://en.wikipedia.org/wiki/Geocentric_model) system in appearance. However, for simplicity, we will need only to examine the one planet case. And more crucially, this one Earth-like body is to be the only immutable part of the design. Clearly we can't have something so massive as an actual star revolve around Earth. So we may explore what kind of luminous moons for this earth could work, natural, artificial or even theoretical. By retrofitting geocentrism I mean giving it a distinct "geocentric vibe." Even though in the strictest sense, it won't be considered a solar system at all. I won't want to take away any answer leeway, but in all likelihood this will have to be a rogue planet that has some type of very luminous object that orbits it. **It won't be required to be naturally occurring, it can be an artificial object and made of theoretical materials.** The quality metric will be to veer more closely on the observable spectrum as opposed to the theoretical. Lastly, by "geocentric vibe" I mean that we have days and nights and an overall convincing appearance and behavior/motion. Heat and gravitational fields to fend off asteroids, though important, will be out of the remit for our purposes. All we require is that object that orbits the sun delivers on the luminosity and longevity fronts (rising and setting every day demands a long-term power supply). [![enter image description here](https://i.stack.imgur.com/8ZsEI.png)](https://i.stack.imgur.com/8ZsEI.png) ## Question How and of what materials, theoretical or otherwise, might we use for this captive luminous body, to have an astronomically correct "geocentric system"? **Clarification:** Perhaps a stumbling block in using the term "geocentrism" is how we think about the "sun". For our purposes, it doesn't have to be a star. It just has to be a scientifically plausible orb that produces similar perceived luminosity and orbital movements when viewed from Earth. Again, the challenge here will be explaining what stuff comprises the orb and how it is powered. [Answer] **Cherenkov radiation moon** Now I'm no expert on radioactive materials and processes and whatnot, but perhaps you could have a 'star' orbit your (probably)rogue planet world by having its moon be a long-forgotten relic of the ancient world, one that is riddled with huge reactors that sit on the floor of a shallow ocean covering the moon and was used in an age long-forgotten as the world's primary source of power and heat in the absence of their star that they found themselves without for whatever reason. The reactors at the bottom of said moon's ocean are still operational and still produce a lot of heat, and light(in the form of cherenkov radiation), giving you something like a blueish star in the sky if it were close and large enough to be perceived as such. This of course assumes your world is some sort of super-earth and that the moon is a smaller earth-like mass world that is capable of holding on to liquid water, but it might allow you to have something of a geocentric system. If your world is large enough to keep an earth-like moon in its gravity well you may even be able to have more than just the moon following it around, so you need not be stuck with just the one moon. [Answer] The glib answer would be *"have the inhabitants be sufficiently egocentric."* Physicists sometimes look if their observations become easier to explain with a [preferred frame of reference](https://en.wikipedia.org/wiki/Preferred_frame). If we are both in deep space, and I am "standing still" while you move away from me at 1 mph, that's almost indistinguishable from you "standing still" and me moving away from you at 1 mph, in the opposite direction. On Earth, if I am "standing still" (relative to the surface of that rotating ball of rock) and you are moving up into the air at 1 mph, the switch would have to assume that you are "standing still" and *both I and the planet* are moving down at 1 mph. That's an equally viable viewpoint, but it complicates all sorts of calculations and observations. At a slightly more complicated level, you get scenarios like "what happens when I jump up and down in a train carriage moving at 100 mph on a curved track?" It is **natural** to start theories with the simple assumption that Earth is standing still. You can have observations fit that starting point by making the sun (as a ball of hot matter, much larger than Earth) rotate around Earth just as easily as you assume that Earth rotates around the sun. The problem with this theory is that the sun and moon would rotate around Earth, and lots of other planets rotate around the sun, and many of those planets have moons. and stars seem to shift in seasonal patterns. So take this system: * One sun. * One planet, with several moons. * In intergalactic space, too far to make up stars from galaxies without *very* good instruments. For all practical purposes, the geocentric frame is just as viable for the occupants as the heliocentric frame. [Answer] Since you state > > Emphasis on geocentric feel. Note that "geocentric" is in quotes. It's for effect only. Tried to emphasize it doesn't have to be in the strictest sense, just scientifically plausible design that would conform to a geocentric narrative if and when inhabitants found out how to to traverse space and observed this "thing" for the first time. > > > you might want to give a look at the [Tychonic system](https://en.wikipedia.org/wiki/Tychonic_system) > > It is conceptually a geocentric model, or more precisely geoheliocentric: the Earth is at the centre of the universe, the Sun and Moon and the stars revolve around the Earth, and the other five planets revolve around the Sun. At the same time, the motions of the planets are mathematically equivalent to the motions in Copernicus' heliocentric system under a simple coordinate transformation, so that, as long as no force law is postulated to explain why the planets move as described, there is no mathematical reason to prefer either the Tychonic or the Copernican system. > > > [Answer] ### ***The Witenagamot Decrees*** ...that from the earliest times, natural philosophy has observed the nature of the Earth and all philosophers have calculated and conjured and taught the same doctrine, namely, that there lies at the centre of our world the coalesced and petrified quantum of all ponderous and heavy elements. Which, due to the forces exerted from within and without alike, rotates upon a sensible axis which is called the irminsul or worldtree. This quantum is known to be round, and as a being of polydimensional space, a globe to be clear, and that we call Earth. Around this globular quantum of ponderous elements arise ever more fluid and energetic elements, each rising in ever more rarified strata from the densest of aethers to the uttermost vacuum, beyond the marches of which lie the Realms of Empyrean. --- [![enter image description here](https://i.stack.imgur.com/4Qu6u.png)](https://i.stack.imgur.com/4Qu6u.png) --- The geologers and geomancers concur with the physicians, the metaphysicians, the alchemists, the astronomers and the astrologers on the natures of the Realms of the World, the Elements proper to each Realm and also the Powers or Forces that act upon them. The ancient wise knew that a limb falls downwards from a tree, that rain falls from the clouds, and that steam rises from soup and smoke rises from fire. The logical conclusion is that two forces act upon all elements, and we call these Gravity and Antigravity. Gravity is that force which tends to draw all things down towards the centre of the quantum, whilst antigravity is that force which tends to draw all things upwards towards the empyrean, away from the centre. Other forces, the lateral force, and the rotational force also act upon all elements, in strength according to the density of of the elements acted upon. We can observe: the rotational force acts most strongly upon the densest of elements, the transplumbians and the deep chthonic rocks, the rotation of which around the irminsul, or axis, causes great turbulence, earthquakes, volcanic eruptions, and the tearing apart of the very Earth itself. Whilst high above the surface of middle earth, in the highest over heavens, the rotational forces only barely act upon the slow stars of the Zone of Weak Lights, and their motion is languid, hardly to be observed at all by mere mortals, yet the astrologers vouchsafe the minutest of motion over the course of many myriads of years! Observing the Four Forces, we therefore conclude that the Model of the Earth's Oecumene is one of a stratified and hierarchical nature. The most ponderous of elements, the heavy transmercuric and transplumbic metals and the densest of chthonic stones aggregate, due to the force of Gravity, into a globe. So much matter of this sort has been so aggregated that it might take a man many years to walk around its girth and come back again to the place where he started! These elements whirl around the irminsul at a rapid velocity, which churns up the waters and silts of seas and lakes and rivers alike. And it is the waters and silts, the lighter metals and less ponderous stones, the various minerals, salts, earths, humours and vitreols that comprise the surface of the Earth upon which we live. Above the solid and liquid boundary of Earth rise the many layers of air. The gaseous and energetic elements of the Zone of Winds and Spirits find their home above our heads! The densest of these elements are the various gasses: such as hydrogen, oxygen, nitrogen, carbonics, steams, vapours, clouds, and so forth. These heavier gasses, are acted upon also by Gravity, which tends to draw them downwards, and also by Rotation, which, due to their intermediate and volatile nature, causes them to rotate around the irminsul at an extremely rapid velocity and in an agitated state. Higher still in the atmosphere lies the Zone of the Mighty Lights and is the home of the Sun and the Moon. We call them luminaries, and the silly Heliocentrists call them "planets"; but in reality, observation carries us to the truth. And that is that the luminaries are ethereal bodies composed of highly energetic elements of varied hue and intensity. We know from telescopic observation of those distant strata of our atmosphere that venereon is a dull and pale yellow colour, helion is a bright phosphorescent colour, and selenon is a cooler, whitish grey colour. Helion is the most energetic of elements in the radiation of heat. This we know, for it is remnants of helion trapped within the materials of earth, such as wood and oil, that cause them to burn with such ferocious heat. The Sun, therefore, is a brilliant agglomeration of helion, burning with such intensity that its heat easily penetrates the thicknesses of the lower atmosphere and even warms the waters of the sea. The heliocentrists argue with the utmost futility that day and night require the Earth to rotate around irminsul and that the Sun lies stationary at the center of the Oecumene. What nincompoops! How is it --- yet they can not explain --- that highly energetic elements such as helion and transarienon are somehow more attracted by Gravity than the ponderous elements of Earth! Nay, they have it wrong. Day and Night are most logically explained by the afore mentioned forces of Rotation and Lateration: being composed of highly energetic elements, the luminaries of Sun and Moon simply move rapidly over the face of the Earth, each with her own velocity and timing, such that both Sun and Moon appear to "rise" and "set" when it is simply the case that the luminaries move towards our eastern horizon, then pass overhead as does any cloud of denser vapour, and then move at last towards our western horizon, which is nothing more than Antipodeans' eastern horizon! Beyond is the Zone of Weak Lights. The two bands of this zone are divided by the astrologers into the swift stars, which those heliocentric buffoons call "planets" and give names such as Ares and Venus and Ceres and Saturn and Mercury and Varuna and Ninurta. These superethereal bodies are not, as some would have us think, solid bodies, but they are conglomerations of highly energetic, though weakly visible phosphorescent elements: notably lumenon, metalumenon and elektron. So energetic are these elements that their light is able to penetrate all the wide and dense layers of atmosphere above the Earth! It might here be noted that it is above the Zone of Winds and Spirits that the effects of Antigravity are felt much more strongly than Gravity. The lighter and more rarified elements of the highest altitude Zones of our atmosphere, being less dense than the clods of solid and liquid matter, hearken more towards Antigravity's pull. It is here that the high and twinkling stars shine forth, tiny pin pricks of nearly invisible elektron and metalumenon! The two highest strata of our atmosphere, and the strangest, to be sure, are the Zone of Dark Matters and the Zone of Vacuum. Dark Matter is very strange indeed. It is so high above the surface of Earth that it can not be seen, for not even the weak light of the highest stars may penetrate and illumine its ebon surfaces. Yet it can be known by the astrologers for it is the source of the strange energy called Antigravity. Just as Gravity arises from within the depths of the most ponderous of elements, deep in the very heart of Earth, so Antigravity arises from its uttermost altitudes where all is dark and obscure. Beyond the highest layers of the darkest matter lies the strangest stratum of all, and that is Vacuum. Here, there is nothing. No mote of even the tiniest speck of elektron or weird strand of Dark Matter penetrates this layer. It is as if Antigravity itself is repulsed! No higher strata of atmosphere are known to exist beyond Vacuum, and beyond its indeterminate borders lies the Empyrean, the extracelestial abode of the Creator, which lies outside the confines of the world. [Answer] ## The moon is a giant nuclear pile Here goes. If anyone is kind enough to fix my formatting, I'll be grateful. The moon has mass around 1 x10^23 kg, and radius 1.75 x10^6m. Earth has radius 1.3 x10^7m. At 3.84 x10^8m distance, earth covers 0.0338 rad angular distance from the moon. (theta = arcsin (radius/distance)). This means it covers 0.00564 of the moon's night sky (areafrac = 1-cos(pi x theta)). And the sky is only half the angular area that the moon would send radiation to. So for every watt received at the atmosphere of earth, the moon would have to emit 2 / arcfrac watts = 354.6 W. In real life we receive 1.73 x10^14 watts of solar energy at the surface, with about 50% having been reflected into space. So earth received 3.46x10^14W total. That means the moon would have to emit 354.6 x 3.46 x10^14W = 1.227 x10^17W, or 3.869 x10^24 J in a year. A kg of uranium emits about 8.2 x10^13 J/kg when fissioned. So the burn rate of uranium is 3.869 x10^24 / 8.2 x10^13 = 4.72 x10^10 kg per year. If this moon lasts 10^12 years, it has mass mass 9.44 x10^22 kg. This is pretty darned close to the real life mass of the moon. This means that this moon of pure uranium, density 19000 g/m^3, has volume 4.97 x10^18 m^3. That gives it a radius of 1.06 x10^6, about half that of the real moon (which makes sense, uranium is roughly 6 times denser than moon rock). In other words, the moon looks and acts very much like the moon does now, but it's a bit smaller and is as bright as the sun. Now, of course, that moon will explode (right, physics crowd? I'm only a chemist / programmer). But that's with it lasting 10^12 years. Shorten that lifespan by a factor of up to 1000 and substitute in inert moon rock. **Now the moon lasts for a billion years. And it looks and acts just like the sun does now.** This assumes that with some proportion of U-235 between pure and 1 in 1000, the moon becomes a stable nuclear pile. And that's where I use my hands; I either hand wave the problem away, or I hand away the problem to a physicist. Alternatively, the ratio could be even lower, but the life of the sun is then shorter. PS What the heck are gamma rays and xrays? You're making things up, nothing to see here. [Answer] ## A red dwarf and a radioactive moon I'm going to lay out a solar system that will satisfy your requirements. It should naturally lead people to geocentrism, it won't have planets 'obviously' (for some values of 'obvious') orbiting the sun, and they might need to develop serious telescopes to figure out what's actually going on. (which won't be a primary driver for the development of optics, because there doesn't seem to be much of a mystery to solve) ### The radioactive moon First let's talk about the 'sun' (that is, the moon orbiting the planet that appears to be a sun). The 'easiest' way I can think of is to have it be highly enriched in radioactive materials. Dump enough, sufficiently long-lived radioactives (but not fissiles) onto the moon as it's forming, and it'll glow (from the decay heat) for quite a long time. This doesn't even have to be dangerous to the inhabitants of the planet. As long as the temperature of the surface of the 'sun' is similar to the temperature to the surface of our sun, they'll put out similar spectra of light, and if they occupy a similar area of the sky (our sun and moon do, though our moon is in too high an orbit to have the required orbital period), the amount of heat and light transferred to the planet will also be similar. [Sean OConnor did some calculations regarding lifetime and energy production](https://worldbuilding.stackexchange.com/a/237944/37575), assuming a stable nuclear reactor. I'm assuming simple radioactive decay, so it's only mostly applicable, and I may do those calculations myself later. ### The red dwarf The next problem is the sun of the solar system, which the people shouldn't see as a sun. There are various options here. #### Red dwarf A red dwarf doesn't put out much light, put your planet in a wide orbit, and it'll look like just another star, though it's one that appears to move around the planet, like a 'planet'. This 'planet' won't have phases, which will keep your scientists from having a mystery to solve there. #### Brown dwarf A brown dwarf is even lighter than a red dwarf, and never got started on 'proper' fusion. As a result, these things have temperatures on the order of 1000 K, and don't emit much light. It'll be hard to see, even if you're fairly close, but you'll still have an anchor for the whole system. The lack of active fusion probably reduces the protection the parent star provides though, however much that is. #### Rogue planet Alternatively, you could dispense with the whole star thing, and just have a planet with its luminous 'star' moon go it alone through the galaxy. This does mean your planet is now exposed to the interstellar medium, though I don't know how much of a problem this will necessarily be. ### Changes your scientists might notice A hot ball of rock&metal and a hot ball of gas emit similar amounts of photons, in similar ranges, but the difference in chemistry is visible to physicists. Absorption and emission lines mean they will definitely notice that the 'sun' has a very different composition than all those stars they see in the night sky. This might be a mystery they eventually solve, or it might cause them to lose interest in further study of the stars. ## Alternative: Just don't have planets If you have just a sun, but no other bodies in the solar system, many of the hints that helped people on our planet figure out heliocentrism will be gone. If you want to go one step further, you can even remove the moon. [Answer] ### A civilization could build an oversized florescent light bulb. Think some big fusion power plants to supply power to a large mostly hollow structure. Phosphor material at the surface to glow appropriate colors. Some novel structures to light up the phosphors efficiently. It would need significant fuel supply and maintenance to deal with whenever something breaks/keep lumen levels stable etc. I definitely have not considered the material requirements for a moon sized light bulb. This could be done by a civilization that was fleeing there soon to be super nova solar system. They want a 'sun' to take with them. Biggest problem would probably be supplying the fuel to keep the fusion plants running. To help could possibly turn off the bulb on side facing away from the home world. If the civilization had moved their home world to orbit a gas giant. Turned the gas giant into a rocket. Then they would have the gas giant to get fuel from. But then it would not be geocentric. But it being a gas giant it would not be lit up so maybe that is OK for the questions scenario? [Answer] # Have a high tech civilization on a Rogue planet Sometimes planets get tossed out into the void, away from all stars. Your planet can have the same issue. It could be a chance encounter with a rogue star or black hole, or enemy action, or even intentionally fleeing their star system. Regardless, they are now shooting through the void of space. If you want the civilization to be lower tech, you could have their civilization fall but their tech remain. # Have a moon with powerful fusion engines and massive LEDs and a gas giant They can convert their moon into a giant torch. They'll need a lot of fuel, so have a fairly distant gas giant that was ejected with the planet. Their advanced machines can draw in hydrogen from the gas giant, feed it to the moon, and use fusion engines to generate a massive light. If you want to show this, you could have the 'sun' have a tail that leads to the gas giant. ]
[Question] [ I have a sapient species in my setting called "mole-bears". I based their social system on eusocial species, specifically naked mole-rats. Mole-bears are on average around 100 pounds and look like six-limbed furless, grey wombats with bioluminiscent markings, they live in underground tunnels and cave systems. Queens are significantly larger, sometimes weighing more than 3 times as much as the non-reproducing workers. Mole-rat colonies range from 100 to 300 individuals. In a mole-bear colony only the queen and her mates reproduce, the rest are sterile female and non-sterile male workers. When the queen dies, another female will take her place, which could theoretically become any female. After the queen dies the females will fight for the position of queen, and the winner goes through some kind of hormonal change that will allow them to reproduce. However, since everyone in a colony is related I want to know how they would avoid inbreeding, since genetic diversity is generally important for a species. [Answer] **Dispersal phase.** <https://www.orkin.com/pests/termites/colony/termite-alates> [![wnged termite](https://i.stack.imgur.com/XjXiV.png)](https://i.stack.imgur.com/XjXiV.png) This is a termite. Like your creatures they live underground. But this one has wings. It is not going to live underground right now. Instead it is going to fly away from the nest where it was born and start a new nest. You can do the same. You have males and nonreproductive females in your nest. If you want to model it on the social insects, some of them have short lived males that fly, and fan out looking for new queens. Then they die. If your story requires male characters they could be juveniles who are expected to leave the nest (e.g. get kicked out) when they growing beards and getting body odor. They wander around looking for a new nest where they are not related to everyone already there and then try to move in. Adult males living in a nest are outsiders who showed up with the right lines and a twinkle in their eye and got invited to stay. That means one might find male mole bears wandering around on the surface. Some might be hopeless as regards prospects of being invited to live in a nest and instead live in groups of similarly loveless mole bear males. Maybe male only bachelor nests? Or maybe finding a place in groups of other sentient creatures who appreciate what awkward mole bear dudes have to offer. [Answer] **Reproductive POWs** Considering that the females fight each other for the position of the reproductive queen I'm going to assume they carry this violence through to females of other nests as well, for exclusive access to males if nothing else(resources, territory, pick your poison). Sapience implies some level of politics to be had, so you can imagine where I'm going with this. One thing leads to another and suddenly the two nests are at war. A skirmish here and there settles some scores and produces male prisoners of war, which are the sole property of the queen whose soldiers won the battle. Said POWs are then used as pleasure slaves/genetic fodder to produce more colony members and introduce new genes into the colony. With a new generation comes new conflicts and the cycle repeats itself. [Answer] How intelligent are your mole-bears? Among primates, either males or females leave their natal band and go join another. Your males could do that. If you want a mechanism, perhaps an adolescent mole-bear starts putting out smells that indicate that he's ready to mate, but which smell repulsive to females that are too closely related. (In fact, in women who are neither pregnant nor on the Pill, men who are different from them smell better to them. I throw in the proviso because pregnant women's taste change, because they are, for safety, avoiding strange things.) The more intelligent they are, the more this could be used as a mating trait. The male who travels the farthest to get to your hive obviously has the most raw talent. Exchange of males could also be used if they were intelligent enough to have peace treaties. [Answer] This doesn't appear to be necessary. Eusocial insects at least generally don't have genetic diversity at a colony level, just at a species level. According to Deborah Gordon, for example, ants in a particular colony are actually more than 50% related to each other (they're closer to 75% related to each other). She actually argues, moreover, that the reproductive unit for ants is the colony as a whole, *not* the individual. (See her excellent book *Ant Encounters* for more details). If anything, this closeness in relation is actually a good thing because individual insects in eusocial colonies often have high mortality rates; for one specific breed of ants, the average lifespan of a forager is *two weeks*. (For obvious reasons, that particular job is typically performed by the oldest ant). That being said, it's important that individuals be "willing" to "take one for the team", so it's actually good for them to be closely related (because then their genes will be passed on by the colony). [Answer] **Your Genes Stink** Literally - the drones are literally unable to mate with the new queen as they share many of the same gene combinations and smell awful to each other. They are repelled and immediately seek out a new hive to be part of. The further a drone roams, the more likely they are to find a queen that only smells great. ]
[Question] [ * ESG stands for [Environmental, social and corporate governance](https://en.wikipedia.org/wiki/Environmental,_social_and_corporate_governance). Simply trying to evaluate what kind of radical "E" solutions are possible if "S" and "G" were removed from the utility function (i.e. were not limiting factors to finding a solution). In a [near-future](/questions/tagged/near-future "show questions tagged 'near-future'") earth world: global temperatures have been rising. More global coalitions have been formed to theorize and plan a policy response, but have mostly resulted in lip-service. Commercial operations have not changed much either. Smaller groups often offset eco-friendly moves by more prominent names, where corporate governance is under the microscope: conglomerate A divests from its heavy industry project, to have the same project picked up by SME Z and utilized for the whole remaining lifetime of the asset. Thus was the status quo and kindling for the events to come. Temperatures increased dramatically, natural disasters, policy impotence, and civil unrest followed. Within a few years, matters worsened exponentially. Then a radical new world leadership, a coalition of military forces from several western countries, emerged. The general public hates them, and the feeling's mutual. The junta's goal: preserve themselves, by virtue of stabilizing global warming. Their means: anything and everything. This is where my imagination needs some jostling: if nothing is off-limits, what is the most effective way to restore the global temperature trend to, say, pre-industrial revolution years? Kill off large amounts of car-driving people? Which people, why? Detonate nukes to induce a nuclear winter? How big a nuke? Where? ## Question **If social and governance concerns were null and void, nothing is off-limits, under existing/known technologies, what would be the most expedient path forward to arrest the trend in global warming?** **Quality metrics:** 1. **Certainty**. Locking in a given cool down effect via xx technology that endangers civilians is preferable to, say, soft guidance on recycling. 2. **Expediency** The sooner global temperatures return to pre-industrial revolution the better. **Clarifications:** * Long-term habitability. While civilians are totally expendable. The small group of world military leaders needs to survive. Therefore measures to offset global warming cannot undermine habitability in the long run. However, the world government is content with bunkering up somewhere safe for a few years if surface conditions are too lethal. * Spare no expense. The decision-makers and implementation team have a monopoly on resources -- which are immense. **Optional supplements** [![heat map of global temperatures](https://i.stack.imgur.com/NekNu.jpg)](https://i.stack.imgur.com/NekNu.jpg) <https://nca2018.globalchange.gov/> One of my favorite quotes from a [great book](https://rads.stackoverflow.com/amzn/click/com/0471295639): > > History does not provide us with thousands of separate and randomly > distributed planet earths and capital markets; the resemblance to > truth is not the same as truth. > > > Along this line of reasoning: To satisfy the most discerning of scientists, we would need an identical planet Earth without people to gauge human's impact on global temperatures. Duplicate several thousand times to form a bell curve. Or as [Taleb](https://en.wikipedia.org/wiki/Nassim_Nicholas_Taleb) famously alluded to, the fact as we are all free-willed humans, we may not have a normal distribution where we have social science at play, but rather something else (T, power). This speaks to, scientifically, how challenging it is to map out humans' role on global warming. For the time being, most seem to be willing to entertain the notion that humans can make an impact, and to err on the side of safety, attempt to dial back global warming triggers (commercial or otherwise). **I'm hoping that for this question, humans can come up with something so spectacular (be it good or evil) that humans' impact on global temperatures is no longer lost in the statistical weeds.** [Answer] **Geo-engineering** There is a [field](https://en.wikipedia.org/wiki/Climate_engineering) dedicated to finding such solutions (which are also present in some other answers). It has fallen into disgrace for its high risks, but has also given lots of ideas of crazy projects for you to exploit. Mitigating sunlight techniques: * aerosols in the athmosphere (the "nuclear winter" idea but without radiations) * white plastic ice caps (reflects more sun light, like painting your house white but on a planet scale) * mirrors in space (giant ones or lots of small ones) * create a lot more marine clouds Greenhouse gases capture techniques: * dump iron in the ocean to boost plancton * industrial carbon dioxide capture * massive reforestation (but forests have a lower albedo than deserts). > > I'm hoping that for this question, humans can come up with something so spectacular (be it good or evil) that humans' impact on global temperatures is no longer lost in the statistical weeds. > > > Then go with the white plastic. Not just on the ice caps, you can add plastic icebergs everywhere in all oceans. It is the most likely solution to have very long term impacts. Space mirrors don't last, and the rest has to be maintained by humans. It also depends on the direction in which you want to go. If they want to "preserve themselves" as world leaders, these projects look like a viable political move, at least for a while. If they want to preserve themselves as in live in a bunker while everyone dies, they can do that without being world leaders. [Answer] So if said Junta was not beholden to the corporate interests and had a relatively free hand to intervene in the market, even radically reshape society, here are some things that could be done to reduce emissions that don't require any new technology **1- Every job that can be done remotely, is** Each car taken off the road saves [4.8 tons](https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle) of CO2 per year. With COVID, a full 41.8% of the American workforce (approx 67 million) is already working remotely. If we applied that figure to the global workforce (approx, 2 billion) and made that permanent, we get 1.16 billion remote workers no longer commuting in cars Savings: 5,568 megatons of CO2 / year. **2- Robust public transportation for the jobs that cant be done remotely** 1 full bus can take [40 cars off the road](http://bic.asn.au/information-for-moving-people/climate-change-and-public-transport), so of the remaining 95.8 million non-remote jobs, if even half of could be compelled to take public transportation instead, this would take another 47.8 million cars off the road, saving an additional 230 megatons of CO2 per year. Compulsion in this case really wouldn't be that hard -- just increase the licensing cost for a private vehicle beyond the means of the average worker and redesign your cities such that the most vital areas can't be accessed by POVs. Applied globally, that would be 420,000,000 workers taking public transport Savings: 2,016 megatons of CO2 / year. **Wind Down the Cattle Factory Farming Economy** Once lab-grown meat becomes commercially viable, subsidize its mass adoption and outlaw large scale industrial cattle farming. This would reduce methane (which is 28x more powerful than CO2 as a green-house gas). 20% of the warming since the industrial revolution is due to the doubling of methane gas in the atmosphere. It would also and free up a whopping [41.4% of all land](https://www.onegreenplanet.org/animalsandnature/america-land-cattle-grazing/) in America (788 million acres) from having to support cattle grazing. No joke, this is going to take heavy intervention by the military Junta. Almost 75% of a cow's bodyweight is usable meat. Cattle farming is big money. There are [1.4 billion cattle](http://www.fao.org/news/story/en/item/197623/icode/) in the world, contributing 40% of global methane emissions - the equivalent of 7,100 Megatons of CO2 / per year or 14.5% of all anthropogenic GHG emissions. Approx 2/3rd of which (924 million) are beef cows. The good news is that Methane breaks down naturally after 10 years in the atmosphere. Were this population of beef cows replaced by lab-grown meat, it would mean **Savings:** * 167 Megatons of methane /year * (equivalent) 4,686 Megatons of CO2 /year And now, the big one requiring the most military intervention **4 - forcefully retire / destroy all or most carbon-based energy production** [84% of the world's energy](https://www.forbes.com/sites/rrapier/2020/06/20/bp-review-new-highs-in-global-energy-consumption-and-carbon-emissions-in-2019/?sh=7972a39a66a1) comes from burning fossil fuels, adding about 34,600 Megatons of CO2 /year. The breakdown looks like this * Oil: 33% (12,400 Megatons CO2) * Natural gas: 27% (7,500 Megatons CO2) * Coal: 27% (14,700 Megatons CO2) * Hydro-electric: 6% * Nuclear: 4% * Renewables: 5% This will be the hardest because unless the vast majority of power is supplied by something else it will drag humanity back into the pre-digital age, causing serious disruptions to our entire society and economy. Nuclear is and remains high and above the clear winner in terms of efficiency and emission (0) - so for countries that have the technology this is probably the best solution and will all but solve the problem entirely. A single reactor can supply about 1 gigawatt of electricity, so to supply 84% of global demand (23.4 terawatt-hours) would require 23,000 new reactors to be commissioned. These huge reactors are old designs though, and there are newer, smaller, less risky ones in research now. One [micro-reactor](https://inl.gov/trending-topic/microreactors/frequently-asked-questions-microreactors/) can now supply ~50 megawatts. I won't call that new technology because its already here just not widely used. It's just a matter of building enough of them, and suppressing the economic / political consequences of forcefully imposing it. A country may be opposed to it but if their oil rigs are literally bombed and they are told "Either build enough renewable energy production to fuel your economy OR you can connect your smart grid to this subsea cable. The other end is connected to our reactor's switch-yard. We will provide all your power now." what choice would they have? It would force countries to stop being hypocritical, paying lip service and continuing to rely indefinitely on problematic energy. Savings: 34,600 megatons of CO2 /year So, all up our total savings: * Remote work: 5,568 Mt CO2/yr * Public transportation: 2,016 Mt CO2/yr * Lab grown meat: 160 Mt methane equiv of 4,686 Mt CO2 /year * Replace 85% of worlds power with nuclear: 34,600 Mt CO2 /year * **Grand Total: 46,870 Megatons (and equiv) less CO2/year** 2020 anthropogenic CO2 emissions were 34,070 Megatons so this would actually put us in carbon negative territory (-12,800 megatons / year). \*\* edits to put all figures in Megatons for readability \*\* \*\* note: savings on transportation are based on US commuter profile only, which is clearly one of the most egregious CO2 emitters in the world. Actual global figures will vary \*\* [Answer] Interesting q, there are few but not sure are they expedient enough for you. First of all, a thing which surprised me, it napkin calculations but, still. A 1km2 land with grass or a forest can produce about 200t of dry plant matter per season. And if I'm not wrong with my calculations but if we take about 10'000'000 tons per day of oil extraction and about 25'000'000 tons per day of coal extraction, then 38% of land covered with grass should be capable to bind all carbon produced by us. Sure our activity is not the only source of carbon, decomposing of plant matter by animals, fishes, insects, and bacteria is one of those as well. So surprising, but killing all drivers, or putting them ballistic electric may not necessarily have such huge expected consequences, so for humanity, I hope this small calculus/observation helps put down some of your fire and save some humans from extermination. Nuclear winter is also a good solid plan, which allows solving the problem of extinguishing all remaining resistance. It(and volcanic activity) lays at the core of proposals of dispersing aerosols in the atmosphere. This approach has its problems - not permanent, hard to control, helps almost as much as not helps(plants get less light and thus bind less CO2), or in case of nuke winter, attention on the word winter, there is no plants, and once you get out of winter plants are dead and the situation is worse than before. ## Comrades, we move into a bright future, all humans unite From experience, your new global order has to have not only a big stick but also a big carrot. Stick has to be real, but carrot can be imaginary. Or I better reword. You may need a big signature project, which brings clear/understandable benefits, in the future, and allows you to justify current actions. Such a move was used for ages, by all kinds of groups. It is not good or bad it is how it works, and will it be good or bad depends on people involved, on goals chosen, and by the - do they succeed or not. ## Signature project Sun umbrella can be such a signature project. What it is? At a bare minimum, it is a patch of non-transparent objects in earth-sun L1 points ([Lagrange point](https://en.m.wikipedia.org/wiki/Lagrange_point)) with a total area of 2.5kk km2 (2.5 million square km's) which is blocking about 2% of energy delivered from the sun to earth. The bare minimum is not such a great way to do so, and it helps us to set a grander goal, but reasons it not that great should be mentioned * +offsets the warming once installed * -not enough control to make things better in the future * -not enough sweet benefits for all, besides it works - no fun, bad review A grander and better solution would be to have a bigger umbrella. And as side products and benefits to become K1 civilization, space living civilization, spacefaring civilization. This can be indications for great management of the new order and its glory, justify some sacrifices on the way, proving the might of technological civilization and humanity. And as a practical achievement it is the ability to not only mitigate warming effects once installed, but control weather in general, and increase the productivity of plants, meaning there are plenty of fun things it can be used for (including extinguishing the last bits of resistance) Potential for hideous things to do on the way, to make it more expedient, mm not sure about it - making all Intellectual Properties a Public Domain or MIT, or CC-BY or one of your choice which you think fits the bill the most. ## timeline I would say two 5-year plans should be enough. One for planning testing designing, one for implementing. Effects start immediately once implementation begins. Some aspects are presented here [How fast could we build a Dyson Swarm?](https://worldbuilding.stackexchange.com/questions/200320/how-fast-could-we-build-a-dyson-swarm/200410) Full Dyson swarm is not required, K1 level is enough. A useful installation it can be - this one as an example [A big primitive computer in orbit, very big, powerfull but old technologies from 80's, what is a potential fiat money value for its use?](https://worldbuilding.stackexchange.com/questions/198172/a-big-primitive-computer-in-orbit-very-big-powerfull-but-old-technologies-from) except it does not have to be primitive and can deliver 4-5 orders of magnitude more calculations, ai training, generative design and other things which can be useful for technologies development. So such a step can not only solve GW but also have a good push for our technologies. And other useful installations in space, so as inhabiting space itself. So, all in all, 5 years to start, 5 years to finish - 10y total and GW is no more and the planet feels better than ever. ## ESG notes in general, the problem is not necessarily in that we limit our solution field by S or G or both, or entertaining an illusion that a solution is possible on the safe side of things. Things are unfortunately worse than that, not excluding the T,power pesky thing, or social crusades for benefit of a few, as usual. There are objective things as well. Corona is one of the examples of how shaky is our current technological fundament, the system of connections, and such. The current most significant factor keeping nations in check is not MAD, but that any global war conflict will be like hands full of sand thrown into the clockwork. Because it was(and still is) not an event that really endangers people, but increases the chance of deaths for a minority of people. (I **do not** underplay potential danger it can evolve into, or harm it does, do vaccination, but compared to some other potential disruptions, which we can do, it is insignificant, and we really dodged a bullet this time, how many more time we will be so lucky.) The notion of absence of common good which is a mindset in capitalist societies, along with the typical incompetence of governance leaders(senators, parliament members, deputies, whatever - it is all the same over the globe - not saying there aren't smart people or that there aren't good ones - it just selection factors at play - sweet-talking which creates a disproportion.) So, distracted, that notion of the absence of common good does not allow us to formulate goals that can be effective, within our capacities, and it settles on local solutions which can get local support (be those effective or harmful, does not matter, 90% are not capable to see those negative consequences, for plenty of reasons, iq is not on top of the list of the reasons) Capitalism is the reason for the problem, so as the reason for it being incapable to solve it until some cost-effective technology is invented. what happens first, is it invented or technology chains disrupted and rip the possibility of such technology to be invented - your guess is as good as mine. Capitalism by itself is that super idea that is in place of some different pan/super idea which could make a solution possible. Communism was such an idea, but it can be anything, sure not just random things, but it can be absurd like build the kingdom of God on earth - as an orienteer, as direction, it less important how practical it is, or how close we are for its realization or how possible it is at all. its important part is how, in which way, it defines the mindset of the human swarm, affects agents of that swarm, in a sense of [swarm logic](https://en.wikipedia.org/wiki/Swarm_intelligence). it was less important a century ago, but today the amount of information required to understand our civilization or its aspects like technologies as an example - that amount is so immense, that it does not matter how smart one is there are no chances to see the full picture of connections of cause and effect. Honestly not such a new problem, it just that back in the days they had a sliver of hope, thus all those philosophers since 2k years, but now is just easy to see - no, there is no hope for that at all and it won't be any better in the future. Further specialization and expert takes, judgment and conclusions will become detrimental for our survival, and it needs to have a situation that has fewer pitfalls for them to sell our survival for short personal benefits. Global warming is not necessarily a big deal, (as mentioned 10y - done), it still can be solved in that capitalist's survival of the fittest way, but what about some next problem we will have? A good pan idea is what we may need. A good in some special way, as for God Emperor may be a good one - one which includes the notion of the existence of common good, common necessity(but please, not in the way dem-party does, even commies were better). There aren't that many things we universally can agree upon, but there are some - life is good and good life is even better is one of those. And because of that, I think that Space can become a basis for such greater idea - it offers resources and solutions for that life and better life, needs just to avoid it to become a second wild west, and some factors are helpful in that - plenty of resources, easy to destroy things - a good basis for negotiations and developing universal approaches of sharing resources in a way beneficial for most ppl. [Answer] **Frame challenge** I dont actually know if you can. The problem with this wish, is that youre trying to stabilise a situation that may have been pushed into a mode where it has its own feedback cycles. In other words,you could do whatever you like within modern technological capability, and sure you can reduce heat trapped on the planet (increase reflectance/decrease greenhouse gases). But if you do all that, i dont actually know if you can arrest the situation, because of the number and immensity of things that may have *already* been set in motion. * Methane and other gases trapped in melting ice/slush, or in the oceans/ocean beds, now disturbed. Very potent greenhouse gases, if these have started to become liberated, they would overwhelm any attempt to reduce CO2 and similar, and effectively with current tech, unstoppable if so. * Giant ice masses at the poles. Again, if those are doomed now, we wouldnt have technology to stabilise or arrest them, i don't think. Because the issue would already exist beneath them. [Answer] **Iron fertilization of the oceans.** <https://en.wikipedia.org/wiki/Iron_fertilization> > > Martin's 1988 quip four months later at Woods Hole Oceanographic > Institution, "Give me a half a tanker of iron and I will give you an > ice age," drove a decade of research. > > > Iron is the limiting nutrient in open water and by adding it one can provoke plankton blooms. Then the biomass (and carbon it has pulled out of the air) eventually falls to the bottom of the sea. Many experiments have been done, both experimental and observational. It works. <https://www.scientificamerican.com/article/iron-dumping-ocean-experiment-sparks-controversy/> One can sequester carbon in this manner without having to make people wear silly hats or eat tofu. But at the cost of much anguished wringing of hands! How can we combat global warming without suffering for our sins and forgoing wrong headed behavior? Windmills! The evil of coal! Bicycles and trees! Condoms! And who will wear all these hats we had made? The junta bypasses that. Handwringers are left to wring hands. The junta fertilizes the ocean with iron. Plankton blooms. CO2 plummets. As a nice byproduct, fisheries everywhere spring back to life. Easy peasy. [Answer] The global climate change is an energy problem not so much an CO2 problem. My personal favourite choice is to build a factory on the moon that produces solar panels. Install those panels at Lagrange point 1. (Between the earth and the sun.) Then use those solar panels to provide cheap electricity to the masses. But any electricity source not from fossil fuels is an option. If you want to speed the carbon capture up some, then you should ramp up plastic production. Those plastics don't break down in the environment resulting in a bunch of coal/oil/gas deposits in a million years or so. If the climate change has gotten already in a positive feed-back spiral then you may be able to arrest that by spreading Sulphur particles in the upper atmosphere. This is also known as Stratospheric aerosol injection. But coral reefs would dissolve when using this. [Answer] Building on @L.Dutch answer (which I upvoted): You have two problems to solve: * Short term you need to avoid triggering nefarious climate changes potentially leading to "Venusian" climate. * Long term you need to stabilize population to avoid cyclically reinsurgence of the problem. For the second there's only a very high degree of social security which makes the cost of a child very high and the value of a family negligence. This means total population should be well under a billion, probably around half a billion (much less than that and you would get problems keeping a "modern" society running). Fastest way to achieve a rapid decrease of population (forget about war and pestilence, they **never** worked in medium/long term) is to disrupt commerce and transports. Start bombing all oil sources and sink (or kidnap) all supertanks. Stay away from large cities for a few months until things settle down. Then your concern is to preserve as much wildlife and biodiversity as possible. This means to start well planned (and better defended) agricultural units in concentrated spaces leaving large areas to wilderness and strugglers which, in absence of commerce and communication are bound to be reabsorbed in a reasonable time frame. A larger and more difficult problem is to stabilize climate and ecosystem. Here you have several, possibly conflicting, needs; listing in roughly importance order: * Stop further increase of temperature. * Prevent "transitory effects" where stragglers destroy what's left of wildlife before succumbing. * Provide shelter and subsistence for "military caste" and all who transition to "new world". -. Provide clean energy to power renaissance. -. Plan a universal "security welfare" good enough to prevent return to "family insurance" leading to baby-boom. -. Stabilize situation. * Maintain a certain degree of control to prevent return to "status quo ante" while allowing for society evolution. Here much depends on the actual amount of technology and resources your "Junta" can muster. One (high expense) solution could be to deploy a large solar sail near L1 (actually more sunward to balance sun-wind pressure) producing a partial eclipse and also providing energy. There are many possibilities, as an example: Have the sail to concentrate light to some mirrors sending light to earthbound receivers/generators; they could be used as weapons ICAI Ed to "unprotected" areas. Using nukes to trigger eruption of several currently quiescent super-volcanoes could trigger a nuclear winter at a fraction of the radiation (less controllable than solar sail, but...). Real problem of **all** these schemes is they are inherently unstable. It is the same problem as dictatorship: usually all "indigenous" (i.e.: not imposed by a foreign country) rise to solve a real problem and, in the short term actually succeed. Problem is absence of "counterweights" makes it impossible to correct even small deviation leading to disaster un the medium term. Please evaluate some scheme to reduce the absolute power of your Junta soon after main aim has been reached. [Answer] As these other answers have given far more comprehensive answers, I will give a more simplified, succinct one. While individual action does affect climate change, the primary changes need to be made from the top, by governments and by large companies. These solutions need to be done with tact and consideration for all side effects. Things like fossil fuel subsidies seem like a no-brainer to remove, but because they lower gas prices, they also lower the cost of products, and thus, cost to the consumer. As many others will be pointing out large polluters, like home heating, transport, food production, etc, I'll just point out that every industry has things that need improving. The creation of roads for example has a really big effect on the climate in comparison to the cars driving on them. A video on youtube from Kurzgesagt – In a Nutshell : [Can YOU Fix Climate Change?](https://www.youtube.com/watch?v=yiw6_JakZFc) This video from Kurzgesagt I think gives some good big-picture stuff, like I've described. I hope that I've contributed somewhat to your question. [Answer] If you really want to achieve long term sustainability, you need to reduce human population. At the current level of about 8 billion people on the planet we are simply too many for it to sustain us. How do you achieve population reduction? One way is to reduce reproduction rates, which appears to be a consequence of security and welfare: once you stop being worried about your future in terms of food, shelter, stability, you make less kids. This, in a nutshell, is what has happened in Europe, North America and Japan in the last 50-ish years, where population growth has gone in the negative range, if immigration is not accounted for. How do you achieve that? Increasing in a substantial way the standard of life in the parts of the world which still have a fast growing population: health prevention, food should be no more a worry. And mind that currently the wealth distribution in the world is very skewed, so redistribution will be necessary. Then of course there is the issue that, even if today magically population would stop growing, there would still be too many living who, because of the measures you have taken, will now also live longer. So, if you don't want to wait about 80 years to start seeing the population count deflate, you should probably resort to some help in cutting the population down: wars and epidemics were pretty effective in the past, and also help in redistributing the wealth, because they shake the status quo in the medium-long term. [Answer] **A mix** It isn't a single solution. It'll always be a cocktail. **Remove all carbon emitting infrastructure, technologies and factories** First and foremost you need to stop emitting more CO². Stop using and building at once. This will be a good basis for reduction. There is an asterisk here. Some can remain, if they are advantageous. Creation of solar panels, or a few all important roads can remain. These can be a starting point for future development and sustaining the human race in an environmental friendly way. **Improve technology** Improving technology is an all important way to reduce or eliminate emissions. Like the invention of the fridge has reduced food waste all over the world, so can many other technologies improve the lives. Think of green alternatives to concrete and asphalt, or a green replacement of rubber. Technology must advance to improve the world. **CO² reduction** Now a two in one. You want dark? You got it. As L.Dutch states, reduction of population is key. Farming, raising animals for food, creation of buildings, infrastructure, transport and energy usage. All are huge contributors to CO² and other stuff in one way or another. All are being used by this population. Reduce the population, reduce the usage of CO² emitting things. Still, so far all solutions, including the reduction of population, is about reducing emissions. Nothing about reducing the actual CO² and other things in the atmosphere. The method of reducing the CO² can be done together with reducing the population. One of the easiest methods to remove CO² from the atmosphere is to grow things that bind CO² inside them and stay alive a long time. Trees are very good at both. Give seeds to a large part of the population, have them seed farmland and tear down/change urban areas to make room for vegetation. Work most of this population to literal death. Their bodies and blood will fertilise the land, helping the spread and growth of trees. It solves much. You need no housing, infrastructure, food or energy for the population that dies. The remaining population can make due with a great reduction in infrastructure and shipping thanks to the sacrifice. The trees will grow quick, as you had 50 to 80% of the population working to make forests before they fertilised it with their own bodies. You can even reclaim deserts with these techniques. The reduction in bad things in the atmosphere will be very significant. [Answer] # Brutal Agricultural Collectivization: A brutal junta has transformed societies before. Over and over, they transform societies to new goals. So your goal is to reduce greenhouse gasses to preindustrial levels and preserve the junta. The answer? Be a brutal, oppressive military junta. It's extremely difficult to eliminate a brutal dictatorship without external supports for your revolution or vacillation by the oppressors. **Reduce the world to a pre-industrial level.** Start by shutting down the internet and stopping broadcast media. Socially isolate everyone from their neighboring lands. Eliminate technology. Eliminate cities and industry. [Pol Pot](https://en.wikipedia.org/wiki/Killing_Fields) was a half-hearted sissy. Force everyone onto farms where they must work for their food - but they don't know it's not just them, because you've destroyed communications. Mandate a vegan diet and eliminate all cattle. Alternatively, [soylent green](https://en.wikipedia.org/wiki/Soylent_Green) is an acceptable source of protein and helps relieve population pressure. Indoctrinate everyone with constant messaging for your eco-supremist message. If resources are limited, do it region-by-region and milk the remaining areas to maintain the military base of the junta as long as possible. Reduce global population to below a billion. Kill everyone at the slightest sign of resistance, or simply by the expediency that the system is inefficient and the guards eat first. Protests don't work if you don't care if the protesters live or die - in fact, you prefer them to die. Only leave a few industrial pockets to maintain technological superiority over the unwashed masses of humanity - now considerably less massive. Plant trees. Lots and lots of trees. Now that you've established your junta as the only possible power on the globe, and reduced the problem to a manageable level, you can slowly introduce any other measures or gradually reestablish a carbon-neutral civilization. [Answer] ## Russia, there is always Russia Global warming is ... * A Bad Thing if you happen to live in the southern part of the USA, or in southern Europe, or in the Sahel (but nobody cares about the Sahel), or in the southern parts of India, or maybe in Australia (but I don't know how many people live in Australia). * Pretty much irrelevant if you live in oceanic Western Europe. * A mostly irrelevant with a pinch good thing if you live in the northen parts of Central Europe, such as Germany. * A clearly Good Thing if you happen to live in Russia, Poland, Byelorussia, and other such cold (or at least coldish) countries. So the first immediate task of the *"coalition of military forces from several western countries"* is to win a war with Russia, preferably without converting their own countries into desolate wastelands. France and Germany will most likely be neutral; England *ought to* remain neutral, but in the last few decades the English have shown that they are less than fully rational and might joint the American Crusade. Australia will probably *have to* join if England joins. And China will observe with unadulterated joy how the western devils are battling among themselves. [Answer] ## Genetic Engineering Doing away with any ethical constraints to solve this problem makes it a great deal easier. The only remaining issue is the initial funding required, finding experts willing to cooperate, and trying to make sure that you do not inadvertently over-do the amount of cooling and force the Earth into an ice age. First, a deadly virus with human-engineered levels of contagion. You would want a fairly lengthy incubation period so it has as much time to spread as possible, followed by instant production of toxins that are both lethal and easily countered if known ahead of time. This way, you can inoculate your own people and anyone your terrorists deem important enough, while the masses of other people die off in droves. The first step alone would likely result in the near collapse of industrial society, but we want to *reverse* what was done to the climate as quickly as possible rather than relying on time and natural processes, hence step two. Step two would be to use genetic engineering to create a specialized form of algae capable of capturing huge amounts of carbon and stabilizing it. This is a lot trickier to accomplish than step one, but I'm fairly confident that a dedicated organization with more money than sense and a lack of ethical qualms could chaingang enough of the scientific community into solving this problem for them. Rapid widespread deployment of this algae into the wild is an ethical disaster with widespread ecological implications, but our goal here is to reverse global warming, so that's not a concern. Assuming everything goes according to plan, we've either solved global warming very quickly, with some "side effects", or we've solved global warming somewhat slowly by killing off all of humanity by accident. Possibly this is Win/Win for your terrorist organization? They are somewhat monstrous. I obviously don't recommend this approach. It's a bad idea. Fun for a story though, I'd bet! [Answer] Apart from all the issues the question suffers (dubious science, decade-long track record of failed forecasting and simply false base assumptions), as well as complete lack of wide awareness of actual climate state of the planet (we're living in an ice age, during a VERY unusual warming period, which was caused by factors still yet unknown), let's take it at a face value. There are some ways to quickly and efficiently stop global warming as defined today and with causes as identified by current warming alarmists. 1. CO2 is most important part of the atmosphere - without it, or even with it at too low a level (somewhere between 180 and 200 ppm) life would not be possible. Plants would die of starvation. Conversely, higher levels of CO2 would mean more lush plant life, extending farther into deserts (as higher CO2 level reduces water consumption by plants), so easiest way out of rising temperatures from increased CO2 levels is to increase green areas by deliberate planting of trees, especially in cities, using every scrap of suitable area (roofs, playgrounds, parks, some part sidewalks, etc.) 2. Reduce human population drastically, for example by releasing highly contagious virus with high enough mortality rate. This solution, though, does not guarantee success, because it needs corresponding reduction in farm animal population, which will actually increase dramatically if one would rid only of part of human population. 3. Invest in high-tech housing heating technologies not using fossil or renewable fuels. While cars are considered big contributors to the global warming, they're actually not. For example, in Central and Northern Europe heating homes is the source of 50-70% of the CO2 emissions (compared to less than 15% from ICE cars). 4. Invest in pipes transporting oil and natgas instead of ships. It is estimated that all the cars in Europe emit same amount of fumes as 200 tankers which carry just oil from suppliers. Switching from sea shipping to pipes for fuels and to trains for goods could reduce emissions globally by about 50%, completely reversing alleged trends. 5. Coupled with conversion of electricity generation from fossil to nuclear would bring that down even more. Though it needs to be done in the distributed manner, because large nuclear power plants do emit quite a lot of greenhouse gasses, chiefly water vapor. So it needs to be done using passive cooling technology and, of course, using tech that can't suffer from runaway nuclear reaction that will cause reactor breaches and/or explosions. 6. Alternatively, one can consider distributed (huge number of small (up to 20kW) hydro plant network. This, coupled with reforestation, would beside generating huge amount of energy with moderate (calculated on per kW/MW basis) initial investment level would have a side benefit of increasing surface and sub-surface water levels by creating huge number of small bodies of water. If those small bodies would be to great extent shaded by trees, evaporation of water from those bodies would also be reduced, contributing to better water retention in conditions closest to those from before explosion of human habitation areas. [Answer] 1. Halt all fossil fuel extraction, distribution and consumption. 2. Radical greening - reforestation. 3. Prohibit wood burning as a means of heating or cooking. Draconian consequences for non compliance. 4. Balance animal farming against plant farming for self-fertilising eco-systems. Previously oil based fertilisers, pesticides and herbicides will have become prohibitively expensive, so better farming practices (organic) will be the only ones economically viable. 5. Draconian anti-pollution laws - the ocean must be cleaned in order for marine vegetation to flourish and do its job. 6. As a consequence of 1 and 2, parts of the planet will become more difficult/expensive to live in - insulation, geothermal, daytime heat storage will all be needed/used to heat homes. 7. As a consequence of 1, people will travel less, people will not drive into work unless their jurisdiction is green powered and they have electric transportation. 8. As a consequence of 1, disposable plastic will practically disappear. 9. Substances like Aluminum, Steel, Cement will only be made using green energy and so will become vastly more rare/expensive. Older technologies will flourish, like straw-bale and clay/mud construction, timber buildings etc. 10. Civilisation will coalesce around green energy sources. ]
[Question] [ Hundreds of years ago, the once-opulent city of not-Atlantis incurred the wrath of the gods and was cast to the bottom of the ocean. Now, our intrepid adventurers have been sent to the lost city of not-Atlantis to retrieve forgotten lore recorded by the not-Atlanteans (along with whatever other treasure they can snag). My question is: **What sort of written media would survive at the bottom of the ocean for a few hundred years?** On one end of the spectrum, exposed paper would degrade and water-soluble pigments would run, which is unfortunate because I imagine these would be very common. On the other end of the spectrum, engraved stone would likely survive, but stone is a rather inconvenient method of recording information unless you deliberately need it to stand the test of time. But there's a lot in between these two extremes. The ancient Greeks are well-known for painting things on pottery. Would such paintings survive underwater? Are there natural pigments, paints, or inks which would survive underwater? Are there paper-like materials which are waterproof and good for writing? The conditions of storage might also change things. Could burying a book in mud at the bottom of the ocean (but not too deep that you can't find it) protect it from decay? It is possible that some of the more valuable tomes were cached in waterproof cases, but what sort of container would keep its contents dry while underwater for hundreds of years? **How could this forgotten lore have been recorded and/or stored to survive underwater for hundreds of years until our adventurers discover it?** Not-Atlantis had a technology level no more advanced than approximately medieval (I could do elements of Renaissance in a pinch, but there is definitely no plastic or digital media). Magic is abundant in this world, but we shall assume non-magical means of writing and preservation for the purposes of this question. The ruins of not-Atlantis need to be mostly navigable, not entirely buried in mud and silt. The water should be suitable for aquatic life. The not-Atlanteans were human-like sea-faring surface-dwellers before the cataclysm, so their common writings would not have deliberately needed to be waterproof (although they may have taken special steps to preserve a small number of choice texts). The less contrived the circumstances for writing to survive under these conditions, the better. I suspect that real-world underwater archaeology and shipwreck salvaging could inform a good answer to this question. There are [several](https://worldbuilding.stackexchange.com/q/59791/55824) [related](https://worldbuilding.stackexchange.com/q/205090/55824) [questions](https://worldbuilding.stackexchange.com/q/65299/55824) on what sort of writing an underwater civilisation would use. This question differs in that we assume methods of writing developed by and readable by surface-dwelling people, and that I am interested in the longevity of such records (although I expect some overlap in the answers). [Answer] Clay tablets Clay tablets have been found in 2,400 year old shipwrecks in the black sea. The tablet is undamaged and completely legible. Since these were also a common form of writing you have no problem justifying writing on them, to last they would have to be fired clay but that was normal for anything intended to be permanent. Unlike pottery it is fairly hard to crush a flat tablet. <https://greekreporter.com/2018/12/12/two-ancient-greek-finds-among-top-10-discoveries-of-2018/> [![enter image description here](https://i.stack.imgur.com/8WGUY.jpg)](https://i.stack.imgur.com/8WGUY.jpg) [Answer] Organic materials don't do well with long submersion, especially in sea water that contains enough oxygen for life to flourish (there are locations in the Black Sea where hydrogen sulfide in the water makes it nearly sterile, and wood has survived for thousands of years, but this requires very uncommon conditions of stagnation). As in another answer, writing on materials that survive long immersion is the best bet -- pottery, stone, precious metals (even iron/steel does pretty well on the single-century scale -- there are a lot of mostly-intact wrecks from WWII and some a few decades older). If someone with modern metallurgy was *trying* to preserve writing in the sea, trading off cost and durability, it would be hard to beat stainless steels -- 304 and more so 316 steels will last a very long time in sea water (because they form a protective oxide layer -- heavy enough to resist even the chloride ions in sea water). Otherwise, platinum group metals (including iridium, osmium, ruthenium, rhodium, and palladium) are very resistant to corrosion (but rare and hard to refine and work) followed by, gold, silver, copper, and bronze (in order of descending durability) -- or heavy, non-porous platings of these on other base metals. One reasonably plausible option would be engraved printing plates (a technology that predates Gutenberg or even Chinese movable type by centuries), which were often made of bronze for its combination of workability and durability. The writing would be in mirror image, but with most languages that's not a big deal once you know what you have. Alternatively, if text written on ordinary paper or parchment with ancient inks (carbon in gum binder, iron sulfate/gallate/tannate, or vegetable dyes -- all of which are vulnerable to water in varying degrees) were being protected for a long sea voyage, it might well have been sealed in barrels, pots, or even glass jars -- and pots and jars have been found that preserved drink and foodstuffs for a thousand years and more. [Answer] Written or decorated pottery, in particular if enameled, is rather sturdy, the main risk coming from physical damage to the substrate. Same goes for carved stone, as long as there is sediment covering it and preventing growth of organisms. [Answer] **Scrimshaw** [![scrimshaw](https://i.stack.imgur.com/0w8ZI.jpg)](https://i.stack.imgur.com/0w8ZI.jpg) <https://museumcrush.org/the-scrimshaw-made-by-an-african-fighting-the-slave-trade-in-1827/> Scrimshaw describes carved ivory, tooth or whalebone. These materials are easier to carve than stone and more durable than wood. They do not require firing like ceramic. Plus scrimshaw is more fantastic. I can imagine public artworks like [Trajan's Column](https://en.wikipedia.org/wiki/Trajan%27s_Column) carved and written on huge teeth and bones from some unknown great sea creature. --- answering question in comment - how long would these materials last? [![ivory from uluburun shipwreck](https://i.stack.imgur.com/1is8L.jpg)](https://i.stack.imgur.com/1is8L.jpg) <https://commons.wikimedia.org/wiki/File:Uluburun12.jpg> This is ivory recovered from the [Uluburun shipwreck](https://en.wikipedia.org/wiki/Uluburun_shipwreck). It is from around 1300 BC. That is not a million years, but is pretty old as sunken artifacts go! [Answer] Your notion that paper doesnt survive underwater is not true. Depending on the conditions, paper and ink will survive just fine. [Scraps of paper](https://www.sciencealert.com/book-fragments-blackbeard-queen-anne-s-revenge-archaeology) form a book were found on Black Beard's ship that sunk 300 years ago. Also, shipwrecks in cold enough water, are expected to have their [documents well preserved](https://www.smithsonianmag.com/science-nature/divers-recover-more-than-350-artifacts-from-hms-erebus-shipwreck-180974251/). [Answer] Partial answer, just in my area of expertise, which is pottery, to answer this part of your question: > > The ancient Greeks are well-known for painting things on pottery. Would such paintings survive underwater? > > > High-fire pottery survives quite well underwater. Glazes on such pottery can be quite vibrant and undamaged even after 500 years in the sea, and there is a thriving antiquities business in Asian "[shipwreck ceramics](https://orientalceramics.com/shipwreck-ceramics/)". So if your Atlantean civilization possessed the ability to fire pottery to 1500C or more, any "documents" on these ceramics would be clearly and easily readable. Low-fire pottery, like that made by the Greeks and Babylonians, however, only survives being underwater in ideal conditions, such as the sterile environment at the bottom of the black sea. There, even low fired red/black ware can [survive intact and colorful](https://newatlas.com/oldest-intact-shipwreck/56916/) for millenia. However, in normal shallow waters, since low fire ware is very porous, it gets used as anchor material and even digested by sea life. Even where the ceramic vessels or tablets survive largely intact, any surface decoration gets eradicated, rendering any writing on the clay (whether via glaze or shallow impressions like cuneiform tablets) unreadable rather quickly. There's one other historical type of clay document that could survive well without being at the bottom of the Black Sea, though, which is fired, enveloped clay tablets. "Secure" documents during the Bablyonian period were enclosed in [outer clay envelopes](https://www.dia.org/art/collection/object/cuneiform-tablet-receipt-grain-and-envelope-33399). Sometimes they were even fired, in order to make a "permanent" record of something. If your civilization had a practice of creating archival records by enclosing them in clay envelopes and firing them, such tablets would survive even thriving sea life, because the damage would ruin the envelope, not the tablet. [Answer] If the data being recorded was important enough, inscribed on gold tablets. Gold is easy to work with and pretty much inert. afaik there's only one acid that will dissolve it. ]
[Question] [ I’m having Gorgons as a race in my story setting. They are not exclusively female, have the lower body of a serpent, and the classic snakes-for-hair element Gorgons had in Greek mythology. However, I’m not sure how the snakes that make up their hair would actually attach to their skulls. I know the snakes have their own hearts and lungs but no digestive organs, that they have their own brains which allow them to act autonomously to some extent, but that the Gorgons can also control them consciously when they want to, at least for the most part. But it’s the connection part that is giving me trouble. How does a snake spine attach to a humanoid skull? [Answer] Think of the tentacles of an octopus, and how they are connected to the head. No bones, yet they are mobile and [rather autonomous](https://invertebrateoctopus.weebly.com/nervous-system.html). > > As stated previously, the nervous system of an octopus can rival many vertebrates and unlike their molluscan relatives, octopuses' nervous systems are concentrated in their heads rather than being nerve knots or ganglia (Williams 2011). The nervous system is divided morphologically into three parts; the central brain, the optic lobe and the nervous system of the arms; the later two are located outside of the brain capsule and are fairly autonomous systems. > > > Same goes for the snake-hairs of your gorgon: the skull is covered with a mollusc-like tissue from which the tentacle/snakes/hair depart. [Answer] They don’t. Warning: If you’re trypophobic (you don’t like clusters of holes) don’t think too hard about this answer. What’s actually going on is that you have two species. The Gorgon is humanoid, bald, and has crater or bulb shaped indentations on their scalp/in their skull, with a lip over the edge. The Follicle Snake is a separate creature with powerful paralytic venom and a strong, coiled tail. The Follicle Snakes curl their tails into the indentation on their Gorgon’s head, seemingly becoming part of them. This offers advantages to both species: The Gorgons get a weapon and the Follicle Snakes gain mobility, a constant heat source and a good, defended place to breed and grow. The Gorgon exerts control on their snake colony by tilting their head, flexing the muscles connected to their scalp (creating gruesome faces) and through training. The snakes in turn alert their gorgon to incoming threats by flexing (or just attacking immediately) How did such a strange symbiosis come to be? This is where it gets a bit squicky. The Follicle Snakes are actually descended from a proto-snake that paralysed its prey before punching a hole in the skin, forcing its tail (hence the strength) under the skin, and laying a cluster of eggs to be incubated by the dying host before hatching and eating their way free. The Gorgons evolved a resistance to the paralytic venom but still occasionally were incapacitated and received a clutch of eggs. They found that by offering other foods to the newly hatching snakes, they could be enticed to *not* eat their host alive, and would instead remain just under the skin, periodically poking their tiny snake heads out to receive food before maturing and slithering into the wild, where they would hunt pests and other nuisance critters (like a horrifying reptilian cat). Eventually this led to the domestication of the Follicle Snakes and almost ritualistic implantation of eggs in the scalp, where a pet snake would offer the most benefit and be the most visible to potential mates (who would be impressed by the obvious strength and vitality of a snake-bearing host). Fast forward a dozen generations and the mature snakes no longer leave the host, instead opting to stay cosied up on top of their heads as a venomous, writhing lapdog. The ‘holes’ are really masses of scar tissue caused by repeated clutches of eggs being implanted, hatching and being nurtured by their now thoroughly social parents/Gorgons. Gorgons with a full head of snakes are seen as excellent breeding partners (with strong necks). Those with an unblemished scalp or few remaining scaly companions are poor or sickly. Good Follicle Snake breeds are docile, trainable or pretty, and can (with effort) be transferred from one owner to another or passed down family lines. The cycle of snake/gorgon interdependence is complete. This does mean that your snakes could (hypothetically) act completely separately from their Gorgon of vice versa, but given the nature of the relationship it would probably be unlikely and require a lot of training the snakes. Though if a Gorgon can train some of their friendly monstrous hairs to be mobile, stealthy snakes with a strong paralytic venom you also have an explanation for the whole ‘petrifying gaze’ myth... [Answer] **Skulls with holes** There's two important things the snakes need. Blood and a sturdy connection. You could attach the snakes directly to the skull and have blood vessels move on the outside, but this would nullify a lot of the advantages of the skull. A hit on the head can easily destroy the quite large blood vessels and kill the Gorgon or in some cases the individual snake due to (internal) bleeding. Also the nerves would be quite vulnerable. The blood vessels can most logically move through the brain, gaining protection of the skull. They don't need the protection of the dura mater, the protective layer around the brain. It can be fixed directly to the inside of the skull. Otherwise it can go straight through the brain, possibly using the voxels (fluid filled chambers for maintaining and further protecting the brain as it works) as much as possible to move to the skull and where it needs to be. The skull itself doesn't need big holes per snake, as you can bundle the blood vessels and nerves (Gorgon needs to be able to control them) very well. The snake is then connected directly to the skull like normal muscles to bones. The hole in the skull isn't a bad thing, as the bundle of muscles and ligaments now protect the skull at that part very well. To have a good degree of movement, the skeleton of the snake can attach to a bumb on the skull. The hole in the skull gets a raised bone, as if the spinal cord has (part of) a snake vertebrae fixed to the skull. This will further protect the skull and the hole, as well as aid connections for muscle and fiber, to allowing blood vessels and nerves to branch out safely. The blood vessels might be connected by a form of placenta. This allows the separation of the hearts, blood pressures and whatnot, while still allowing for important nutrients and such to be transferred. It also allows a snake to die safely when cut, disease or old age. No bleeding out of the host. This would also allow new snakes to grow. Interestingly enough they could get some protection from the different immune systems, but these shouldn't be too different to work. Immune responses in normal pregnancy are already suppressed to prevent rejecting a baby. With snakes and Gorgons this could be much more difficult. [Answer] **Mechanical, vascular, and neural connection** The snakes need three kinds of attachment. They need to be mechanically well anchored. This requires attachment points on the skull for the muscles and ideally for the spine as well. They need their blood vessels connected to the medusa's, because they do not have their own digestive systems---they get their nutrients via connected blood flow. But what most other answers neglect is the neural connection---if the medusa can override the snakes' brains and control them directly, then their spinal cords must be rooted into the medusa's brain. These considerations yield the following: 1. The snake spines are connected to the skull in much the same way our spines connect to the pelvis. 2. The spinal cord and major spinal blood vessels pass through the skull and root into the brain and vascular system, respectively, on the inside of the skull. 3. The snake's muscles are attached to an annular enthesis on the skull. Note that individual lungs and hearts in the snakes are not necessary at all. Instead the snake is all spine and muscle, which makes it stronger. It is essentially a limb, but with eyes and an autonomous brain, and a nasty venomous bite. ]
[Question] [ I'm working on an alternate-history story in which peaceful alien satellites are surveying the solar system and passively observing human activity. Many of the deep-space satellites would have been in long orbits, communicating with one another mainly through radio signals. (Edit: They are mostly doing a mineral survey of the solar system at large, and studying the course of humanity's technological development. They intend to make contact with humans at some later point, but have not yet decided when to do so. There are a few long-orbit satellites studying the outer planets, but the greatest concentration is from the asteroid belt inward, as well as communications relays in Earth orbit.) In real history, pioneering radio astronomers in this era detected radio signals from distant celestial objects such as Cygnus A, and were able to map many stars in the Milky Way. 1. If there had been alien satellites in the solar system at that time, would radio astronomers have been able to intercept their communications? 2. Would it have been possible for mid-20th-century terrestrial radio technology to send signals *back* to space, and establish two-way communication with these devices? [Answer] Yes. Assuming they communicate in (almost any) radio frequency AND They are communicating directly at Earth. AND We are actively looking for something, or their probe accidentally happens to be in the ***exact*** same direction as one of ours. (accurate to within a few thousandths of a degree) If the aliens device communicated via laser, or tachion beam, or polarized gravitometric pulses, or hyperwave, or by rapid engublification of it handwavium vanes, then obviously there is no ways we can detect it, even if it is sitting in the vacant lot next door. As for them needing to be talking directly at us... Consider the case of a Voyager Probe. When it is talking directly at us, the signal is so strong that you only need an antenna the size of 4 football fields, pointed *exactly* at it, and listening for a signal on its known frequency. If the signal is pointed far away from Earth, say more than 1/2 of a degree off target(thus out of the peripheral lobes of the x-band antenna), then that receiving antenna would need to be several millions of times bigger. And if the Voyager is not actively transmitting, then the detecting antenna would need to be.... many times bigger than the Planet Earth itself. We can safely assume that alien probes have better antennas with better focus. So, realistically? **Yes but only if the aliens WANT us to hear them.** As for communication: If we can actually receive (and send) signals with the alien probe, then ***of course*** we will be able to communicate. Because, as shown above, this will *only* happen if ***the aliens want to communicate***. Being much much much more advanced than us, they will of course have listened in on our own radio & tv broadcasts, figured out suitable communications protocols, and will be transmitting it to suitable receivers at sufficient amplitude in familiar encoding formats. [Answer] **Yes, probably, in a fashion.** Remember, we're talking about the decade of *Sputnik* and *Explorer*, and Mars programs *failed* in [1960](https://en.wikipedia.org/wiki/Mars_1M). Building the ground-based portion of such a program just a few years ahead of the historical schedule should be possible, given proper motivation. Sending signals to them is not the same as establishing two-way communications. Unless the alien sats have been **programmed** to aid human communications attempts, mankind would face quite a challenge to get into their communications protocols. Do you know what an [email header](https://en.wikipedia.org/wiki/Email#Header_fields) is? Could you write a plausible set of headers down from memory? And that's with the fields being in English, now imagine a space-saving format of bits and bytes. (How many bits to the alien byte? You can see the problem, I guess ...) That challenge would be taken by plenty of very smart people, using the best computers available. I'd compare it to [breaking codes in WWII](https://en.wikipedia.org/wiki/Ultra). The codebreakers have messages without context and look for patterns. [Answer] Don't confuse detection with communication. Detection is just the reception of the signal and the determination of it being of artificial origin. That's highly plausible or at least not out of the realm of possibilities. Communication means delivering signals in a way that can be read and understood by the receiver. For the reception part from our side, that would require being able to determine how to read the data and to break their eventual coding protocol (to stay simple, think of some aliens capturing the sentence "the Eagle has landed" from Apollo program, what could they infer from it? If you want to be more complex, think of how data from space probes are compressed.). Then for the sending part, it would require knowing how and if the receiver is programmed. I would say this is extremely unlikely. [Answer] Most systems are encoded on several layers. ### First encoding: the channel There is a channel encoding, on the bottom-most level, which deals with the specific stuff needed for the analogue world. Normally, if it gets sophisticated and high speed com, it resembles white noise and so is difficult to decode. Especially if you have much slower signal processing than the sender assumes, you just can't get the content out in time to react. In the analogue world, those normally are a combination of too-high or too-low frequencies in several steps, phase shift of the waves as often as every quarter wave (the wave comes a bit too early, on time or too late); amplitude changes (louder or more silent), all of this in arbitrary combinations and arbitrary fine steps. 8 bit is a digital native, the analogue world can have chunks which are smaller or bigger or oddly numbered, depending only on what is practical with this transmission technique. Imagine you have 3 phase steps, 3 amplitude steps and 3 frequency steps, then every quarter wave will carry 27 bits. Some of it will be used for error correction and has to be removed in the net transmission cpacity, but still, these can be quite unusual numbers. There are two upsides: satellite communication is often very slow for long ranges, in order to avoid transmission errors, and can be repeated several times. So you have a chance. And all those changes move around a central frequency, the carrier, which is mostly detectable. ### second encoding: the network protocol Then you normally have some kind of network protocol, the best known of which here on earth is tcp/ip. Those protocols have the task to determine sender and receiver and routing, provide some extra data and additional error correction. The point is, any message can be cut up in many small chunks and every chunk will contain all the protocol header. This is a repeated part of the message, a gold nugget for the deciphering cryptography people and probably the part which enables the cracking of the channel protocol above. ### compression This is the hardest. Compression algorithms can be incredibly sophisticated. You won't understand jpeg or mpeg by just looking at the data. Zip compression yes, if you're lucky. But then, who says that the aliens are not using something even more crazy? Even we have jp2 since 20 years as replacement for jpg (even if it is somehow not used), they may have something way over our heads. ### email header and text Someone else here mentioned the email header. This is a protocol overhead for the payload. If you are here, you have won! After all, you'll get the payload now. ### conclusion I think you can detect it. I seriously doubt you can decipher what it says to another satellite with fifties tech. I guess you can send something to the satellite with a big enough dish. And then, if the satellite is programmed to react on this crude analogue signal, it could answer using the earthling's protocol. That would be communication, but the satellite must be specifically programmed to do this. [Answer] **Anywhere from ~1940 to not yet.** > > The first purpose-built [radio telescope](https://en.wikipedia.org/wiki/Radio_telescope) was a 9-meter parabolic dish constructed by radio amateur Grote Reber in his back yard in Wheaton, Illinois in **1937**. > > > --- > > The cosmic background radiation [(CMB) was measured](https://en.wikipedia.org/wiki/Discovery_of_cosmic_microwave_background_radiation) by Andrew McKellar in **1941** at an effective temperature of 2.3 K using CN stellar absorption lines observed by W. S. Adams. Theoretical work around **1950** showed the need for a CMB for consistency with the simplest relativistic universe models. In **1964**, US physicist Arno Penzias and radio-astronomer Robert Woodrow Wilson rediscovered the CMB, estimating its temperature as 3.5 K, as they experimented with the Holmdel Horn Antenna. > > > Discovered in 1941, the CMB took until 1950 to surmise what it was, and till 1964 to prove it. It took two years to find the first two [pulsars](https://en.wikipedia.org/wiki/Pulsar) (1967-68) to discount the 'Little Green Men' hypothesis of having found the first one. However, pulsars were first posited in **1934**. So let's say by **1940** you have the tools to do it, and an inkling of what it might be (or more importantly, what all these stray radio signals from space *are* and *are not*), but proof is still a few decades off. That is unless you figure out some kind of signal to send to one of the satellites that triggers a response. --- The ability to send the signal isn't the problem, it's what to *'say'*. If it's a *'first contact'* system they would've made it easy for us. If it's encrypted you're going to need computers. Or if you're lucky they didn't even bother because they didn't plan on us being here. [Answer] For detection, no, assuming that the aliens don't actually want their satellite communications to be detected, and are competent electrical engineers. They would have used beamed radio communications, or possibly lasers &c, and would have taken care not to point the beams at Earth. For comparison, consider satellite TV antenna dishes, which have to be pointed pretty much directly at at a particular satellite (a mere 22K miles/35K km away in geosynchronous orbit),and which is trying to have its signals received. Communication, maybe, if the satellites have been detected and frequencies known. After all, radar beams were bounced off Venus, and the return signal detected, starting in 1961. The problem, though, is discovering the communications protocol to be used. After all, if you don't use the correct protocol for your cell phone, bluetooth device, WiFi router, or whatever, it's just noise, not communication. [Answer] > > If there had been alien satellites in the solar system at that time, would radio astronomers have been able to intercept their communications? > > > Only if the observers were lucky *and* the satellites had no desire to hide their transmissions. First, you have to be looking in the right direction, at the right time, at the right frequency. But then you have to recognize that the incoming energy is a *signal* - which means that it has to be coded in a way that you can detect, and expect. 1950's technology still used fairly simply effectively *analog* modulations - signals of interest had lots of energy concentrated in narrow bandwidths. But many modern schemes are instead spread-spectrum and can only be detected by a receiver seeking a comparable pattern. Even something not trying to hide - say our own contemporary GPS satellites which transmit different coding sequences all in the same frequencies - would be difficult to detect as *intentional radiators* with 1950's gear, unless someone knew exactly what to build gear to look for. Something so close might be seen by reflecting sunlight or on an early active radar search, but that's distinct from *intercepting its signal.* > > Would it have been possible for mid-20th-century terrestrial radio technology to send signals back to space, and establish two-way communication with these devices? > > > If the satellites were design to make that possible, then yes, most definitely. If you wanted to communicate with an early electronic society, you'd go to efforts to make things easy. You might try some very longwave frequencies for ultra-primitive situations, and your classic physics-inspired SETI ones, but if you're orbiting someone's planet you'd mostly you'd pick the low VHF range where you easily get energy through an ionosphere, while remaining in the realm of what can be done with vacum tubes. Then you'd use (at least at the outer attention level) simple modulations, for example toggling between two discrete nearby frequencies in such a way that you elicit a response from all of your basic detector types (BFO, AM, FM). And you'd use it in a way that creates a "curious" pattern such that a lifeform *manually* noticing the signal finds it interesting enough to bring it to the attention of someone who can hook up more instrumentation to look at it. Finally, you encode your meaning in terms of basic mathematics - prime numbers and all that, and in a self-teaching way. Our own science fiction authors and actual real world outgoing contact attempts have examined the possibilities there. To some extent though, to have a meaningful "conversation" you have to pack a fair amount of AI into that satellite. And if you're going to do that for the meaning, you might as well do it for the communication, too. **In other words, you monitor your target civilization's own communications, and you respond in kind.** If they call each other with a particular pattern, you use the same pattern. If their broadcast stations turn off a certain period after the local star rotates past the horizon, you jump in an instant later with your own "greetings planetenials" message - *or simply replay their own traffic of the previous platentary revolution*. In short, **you get their curious individuals curious, and you make the task of responding within reach** [Answer] > > Many of the deep-space satellites would have been in long orbits, communicating with one another mainly through radio signals. > > > The alien satellites would know where each other is, and would transmit using dish antennae aimed at each other just like we do, to concentrate the signal; otherwise, 99.999% (probably much more) of the energy would be wasted going in directions which serve no purpose. Therefore, **no** we would not detect those satellites in the 1950s or even now. Here's a picture of the antenna on the Voyager spacecraft. Without the dish aimed directly at Earth, we couldn't detect it's *faint* signal. Alien craft would have a similar problem (though presumably with a higher energy budget). [![enter image description here](https://i.stack.imgur.com/qBX5X.gif)](https://i.stack.imgur.com/qBX5X.gif) [Answer] In addition to all the other answers indicating that we would only be able to intercept radio communications from the alien sattelites if they were transmitting directly in the direction of earth, I'd like to point out another way to observe them: Satellites in low earth orbit are visible with the naked eye, because they reflect sunlight. Just like the moon. If you go outside on a clear night you can see them, dots moving along the sky. If the aliens have satellites in earth orbit they will be visible, unless they take steps to hide them. I'm not sure if satellites in medium or high orbits will be as visible, but at least they would also be visible with simple telescopes that were available long before the 1950's. My guess is that satellites in earth orbit would be discovered before the 1950's unless they had measures to hide themselves in place. Hiding a satellite is probably as simple as putting a big mirror on earth-facing side, and making sure the mirror is oriented so that it reflects sunlight to anywhere but earth. Without such hiding measures, satellites would need to stay out of earth orbit. Maybe a very distant orbit would work, I'm not sure where the limit is. At least beyond the distance of the moon, I'd guess. Or they would need to use orbits at the lagrange point behind the moon or the lagrange point between earth and the sun (you can't point your telescope at the sun). [Answer] There are two ways an alien probe might indicate its presence: optically or via radio waves. Technically radio waves are incorporated into optics, but by optics I'm referring to the visible part of the [electromagnetic spectrum](https://en.wikipedia.org/wiki/Electromagnetic_spectrum) (red to violet light: 380 to 750 nm wavelengths). ## Detection via Visible Light Waves [Visible light astronomy](https://en.wikipedia.org/wiki/Visible-light_astronomy), could detect a moving object within the solar system if telescopes where pointing in the right direction. The movement of the object would be noticed against the background of distant stars that from our perspective appear stationary. By observing the moving object over a period of time a course can be determined. If the course followed by the object orbits the Sun it would be assumed the object could be an asteroid or a comet. If the object followed a "weird" path that did not orbit the Sun, but moved from planet to planet, or something else, it would be noted as something peculiar. Consider the consternation caused by [Oumuamua](http://hhttps://en.wikipedia.org/wiki/%CA%BBOumuamuattps://) in 2017 when it came very close to Earth. It was the first object from outside the solar system to enter the system that was noticed. There was speculation by some people that instead of being just a rock from somewhere else it might have been an alien probe with the appearance of a flat rock. Now if an object was detected optically, in addition to its path being weird if it flashed in an unnatural way, something akin to a type of alien Morse code, or a repetitive sequence of prime numbers then someone might postulate the object might be of extraterrestrial origin. The technology and means for optical detection existed in the 1800s. ## Detection via Radio Waves Regarding radio waves the availability of technology and people needs to be considered. World War 2, which occurred during the first half of the 1940s affected both. ## [Radio Astromony](https://en.wikipedia.org/wiki/Radio_astronomy) The first detection of radio waves from an astronomical object was in 1932, by Karl Jansky who was with Bell Telephone Laboratories when he was investigating static that interfered with transatlantic shortwave voice communications. Inspired by Jansky's work [Grote Reber](https://en.wikipedia.org/wiki/Grote_Reber) built a 9 m parabolic radio telescope in his back yard, in Wheaton Illinois, in 1937. As others have stated in their answers, to be able to detect anything one has to be using the correct radio frequencies. Reber's first two attempts to detect anything from the cosmos failed because he used frequencies of 3300 MHz and 900 MHz. He only started getting results when he used 160 MHz. He ended up completing a radio frequency map of the skies in 1941, which was extended in 1943. Until the end of World War 2, Reber was the ***only*** radio astronomer in the world. People started to enter the field of radio astronomy after World War 2. Confirming radio emissions from the Sun was some of the first work undertaken, usually using repurposed military radar equipment from World War 2. [Ruby Payne-Scott](https://en.wikipedia.org/wiki/Ruby_Payne-Scott) was the first female radio astronomer from 1946 to 1951. Many of the world's iconic radio telescopes where not constructed until the late 1950s, or even later: * [Dwingeloo Radio Observatory](https://en.wikipedia.org/wiki/Dwingeloo_Radio_Observatory), Netherlands, completed 1956 * [Jodrell Bank](https://en.wikipedia.org/wiki/Jodrell_Bank_Observatory), United Kingdom, established 1945, near Manchester. The [Lovell Telescope](https://en.wikipedia.org/wiki/Lovell_Telescope) completed in 1957 * [Mullard Radio Astronomy Observatory](https://en.wikipedia.org/wiki/Mullard_Radio_Astronomy_Observatory), United Kingdom, established 1945, near Cambridge. * [Parkes Observatory](https://en.wikipedia.org/wiki/Parkes_Observatory), Parkes, Australia, built 1961, operational 1963 * [Molonglo Observatory Synthesis Telescope](https://www.sydney.edu.au/news/physics/1737.html?newsstoryid=15590), Australia, 1965 * [Goldstone Observatory](https://en.wikipedia.org/wiki/Goldstone_Deep_Space_Communications_Complex), California, USA, established 1958. * The now decommissioned [Arecibo Observatory](https://en.wikipedia.org/wiki/Arecibo_Observatory), Puerto Rico, completed November 1963. * [University of Illinois Radio Telescope](https://ece.illinois.edu/about/history/reminiscence/400ft), 1957 * [Green Bank Telescope](https://en.wikipedia.org/wiki/Green_Bank_Telescope), West Virginia, USA, October 1961. * [Pushchino Radio Astronomy Observatory](https://en.wikipedia.org/wiki/Pushchino_Radio_Astronomy_Observatory), Russia, established 1956. Four 22 m radio telescopes completed in 1959. * [Nançay](https://en.wikipedia.org/wiki/Nan%C3%A7ay), France, inaugurated 1965 * [Effelsberg 100-m Radio Telescope](https://en.wikipedia.org/wiki/Effelsberg_100-m_Radio_Telescope), Germany, inaugurated in 1973 So if you want to set your story in the 1950s, then the signal could have been received in either: the Netherlands (1956), the United Kingdom (1957), the Soviet Union (1959), USA at Goldstone (1958) or possibly the University of Illinois (1957). The other thing is, just because a radio telescope exists doesn't mean it can receive all signals. Size matters, the bigger the better, particularly for very weak signals, as NASA discovered during the Apollo 13 emergency when its 22 m diameter dish at [Honeysuckle Creek](https://en.wikipedia.org/wiki/Honeysuckle_Creek_Tracking_Station), near Canberra, Australia could not clearly and [reliably receive communications](https://www.bbc.co.uk/programmes/p04xx7mz) from the [stricken Apollo 13 craft](https://www.abc.net.au/news/2010-04-14/canberras-crucial-role-in-apollo-13-rescue/395420). The [Parkes radio telescope had to be quickly converted](https://curious-droid.com/284/australia-helped-save-apollo-13/) from a dish that just received radio signals to one that could send and receive. A serendipitous signal like the [Wow! signal](https://en.wikipedia.org/wiki/Wow!_signal), received in 1977, could be a good analogy for what might have happened. ]