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[Question] [ Plausibility check of the whole "insect race". As background, I want some poor astronauts to "crash" (safely land, but because they *had no other option*, possibly some engine malfunction) and meet with my *insectoid* race. But... **How would they communicate?** I will put *you* in the situation. Imagine that you are magically "warped" to different planet with bit thicker atmosphere and bit lower gravity. You are still able to breathe, it just feels like being on top of mountain. You are able to move, just feel bit lighter. And then you meet something huge, looking close to Earth ant, but 1 meter (cca 3 feet) in size. 1. How would you tell such animal is actually **not an animal,** but intelligent creature? 2. How would you try to tell them, that you "come in peace"? You can assume: * You know you are on planet which has technology level of our current space exploration (you know about satellites on the orbit) * Your counterpart has same way of thinking as you, and you look the same *ugly and scary* to them as they to you * This creature is active member of [Outdoors](https://outdoors.stackexchange.com/) alien counterpart of Stackexchange on given planet (and is on a hike to the woods right now) * This creature is also a member of an alien Worldbuilding site, thinking of how two-legged aliens could look like [Answer] ### How to tell they are intelligent I think the easiest way, in both directions, to determine intelligence would be to see artifacts, such as clothing. If the ant has ant pants, it's probably intelligent. If it seemed intelligent, but didn't recognize the same about me, mathematical sequences would be a good bet. I can be fairly sure that an advanced race with its own stack exchange probably has things like counting and Fibonacci sequences, so I'd try to get it to recognize those, and use that as a basis for starting communication. ### How to "come in peace" Without communication, this would be tough. I'd probably rely on sitting down and being nonthreatening. Any human/Earth animal body language probably won't mean the same thing on this new planet, but I can at least try to make it obvious that I'm not attempting to attack. I'd avoid physical contact. ### How to communicate This would depend largely on how the other race communicates. If they speak and read, I'd probably start with basic pictographs to try to establish some common language. If they're blind and deaf and communicate through touch and electrical signalling, it would be much tougher to figure things out. In this case, I'd probably try to establish that I'm intelligent, and then follow them/let them lead the way in communication, since they'd probably have a better chance than me at teaching touch-based communication. Alternately, I'd check and see if their radio signals are similar to human ones, and see if I can communicate with them via any onboard computers and radio transmitters that have survived the crash, but this would be a last ditch effort, since I'd prefer to be able to communicate physically with the inhabitants of my new planet. [Answer] Well one of the big things that would give a clue to the possibility of an intelligent species is the use of tools. This does not mean you need to catch the ant using a hammer to pound something. Clothes, back packs, communication devices, hat, helmets etc. Humans rarely wander far from their homes without some tool to help them on their journey. Now if the species is self-sufficient enough not to need these things and you just have a large naked ant, without even a bandoleer to hold a mid afternoon snack, you are going to be stuck with observation of behavior. This would be MUCH harder, since a species that has such different biology and world view 'intelligent behavior' could be very different. Not only that, are the ants, aggressive? passive? carnivores? 'stone age tech? information age? [Answer] This is just a slightly special case of the general question, "How could we tell if an alien race is intelligent or convince an alien race that we are intelligent?" Adding the detail that they are giant ants and the human ship has made an emergency landing would likely change the details, but the big question is tough enough without getting into details. I'm sure thousands of science fiction stories have been written exploring this idea. For starters, what is the definition of "intelligent"? We often talk about using tools. But people have trained animals to use simple tools. I saw a documentary years ago about animals in nature using simple tools, like a bird trying to reach the water in a bottle with an opening too small for its head, dropping pebbles into the bottle until the water level rose to where it could drink it. Was that "intelligent"? Etc. While the aliens in most SF stories think and act just like people, the only difference being that they have blue skin or pointy ears, some writers have tried to craft a truly alien intelligence. (Aside from the dull standby "they have no emotions", which always leaves me wondering, Then why do they do anything at all? It's a paradox to say that they have no emotions because they are so proud of their refined logic. Isn't "pride" an emotion? If they don't love or hate anything, then that must mean they don't love life. So why would they lift a finger to protect themselves from a wild animal attack or a heavy object falling on them? Wouldn't they all be dead within a few months? Etc. But anyway ...) Could aliens have a totally different mathematics, for example? Could they never have thought of the idea that 2+2=4 but be very advanced in, say, Euclidean geometry? It seems theoretically possible but difficult to imagine how it would work in practice. Would aliens wear clothes, or is that something peculiar to humans? One could imagine aliens who do not get sexually excited at the sight of each others' bodies -- maybe who don't reproduce by sex at all -- and who have never thought of the idea of fashion, i.e. clothes for decoration, and so only wear clothes when necessary to protect them from extreme weather, etc. Aliens might communicate in a way imperceptible to us, like they might have radio transmitter and receivers built into their bodies. Or they might communicate in a way that we can perceive, but that would be too far from our thinking or too subtle for humans to notice. Like emitting odors in a specific pattern, blinking their eyes in Morse-like code, etc. I'm reminded of an SF story I read many years ago -- sorry, I forget the title and author -- but there's a scene where humans meet aliens, and eventually one of the humans figures out that the aliens communicate by sending microwave messages. At this point one of the other humans says, "You mean they communicate by telepathy?" And the first person says, "Sort of. But to them, so do we. They don't think of sound as a method of communication, so when we talk to each other" etc. Anyway, books can and have been written on this subject. I can't imagine you'll get a complete, definitive answer here. I'm just throwing a few thoughts in to chat, basically. [Answer] First do not start by attempting to shake its "hand" - haha! **NOISE** The first thing that occurred to me is that *you are already providing the insectoid creature with a host of stimuli* that you do not typically attempt to control for the purposes of communication: * **scents and particulates** - we are a mess of bacterial colonies, bodily fluids, hormones, pheromones and active pathogens, dead skin cells, crystallized proteins, acidified water and water vapor . . . Our ant friend might not be able to stand the smell of you and worse, might have an extreme allergic response to you. You might even be saying some things you really don't have on your mind (eg. "*wanna go on a date, you sexy thing, you?*") * **electromagnetic fields** - your brain and heart are creating electromagnetic fluctuations that could be reasonably be detected from 6 to 9 feet with sensory organs similar to those in catfish and sharks. You might be saying "HI!" once or twice every second or counting "1,2,3,4,5 . . ." - which could get annoying for your listener. * **electromagnetic radiation** - you are emitting 900+nm wavelength light as long as you are warm enough to be alive. You might appear to the ant creature as a blurry, brightly glowing creature. It might associate you with fire or the sun. To deal with all of these, I hope you keep your space suit on for just a little while - an intelligent creature (especially one with an exoskeleton) should understand that you need those hard things on the outside for protection. Once you have established that the ability and desire to communicate exists (using methods described by other users here), I would suggest attempting to open one communication channel at a time, allowing your host to observe and in turn, looking for any kind of observable reaction. If there is more than one creature, you may have to watch the others for signs of a reaction - they may communicate using a method you cannot observe directly. try moving from what you assume are secondary communication channels to what you assume are primary communication channels. The first thing you want to communicate is that you are attempting to communicate. **COMMUNICATION CHANNELS** * **light** - if the creature lives above ground on an illuminated planet, this is a safe bet and you can set the stimuli to fall within ambient light levels * by extension, **gestures**, if you think you are sensing a gestural pattern from the creature. * **sounds** - at levels just above ambient noise levels * **ordering objects** in the nearby physical environment (large to small, hard to soft, etc.) * following a **logical path** around obstacles to and from a destination (an ant creature should appreciate that :) ) * **Providing the creature with something it needs or wants**, determined by observation - something it eats, for example. Eventually, you could open the visor of your helmet and attempt communication with controlled emotional responses using some form of biofeedback (such as an immediate response from the ant creature). This would be exposing the creature to *hormones, pheromones, gases, particulates and foreign pathogens* though - so, don't be surprised if you run out of time to test communication methods because your communication partner is asphyxiating, offended, enraged, high, or dead. [Answer] The first question is: What would be the first reaction of the ants on seeing the humans? * Run away. Well, that's completely natural behaviour, and there's nothing you can tell from that; also, they are now gone, and so any communication attempt is moot anyway. *However* if they are intelligent, they'll likely come back (not necessary the same individuals) in order to learn more about those strange ugly creatures (if only to determine whether they are dangerous), or if the astronauts are unlucky, to kill them (in which case the second option now applies). * Attack. Trying to communicate in that case is probably moot because you try to keep alive. However the attack behaviour would likely give away the intelligence; if not immediately, then after later analysis (which would have to be done because, after all, they could attack again, and you want to be prepared). * Ignore you. Well, in that case, you could observe them in order to determine whether they are intelligent. You could also try to get their attention, but then you risk that they would attack you. Of course, it could also lead to the next option. Of course you could also use being ignored to study them to learn more on how to finally get to the last option (but careful to not do anything they might see as attack, leading to the previous option). A long time being around without any conflict would also make them more likely to believe that you're not going to attack them. * Show interest in you. That's the best case: The way they show interest almost certainly will give away their intelligence, and moreover you have their attention without having to defend yourself. So now you are in a situation where you can try to communicate. As ckersch already wrote, the best way to signal that you are intelligent is to use mathematics and build on that. And the only way to signal that you are peaceful is to avoid anything that could be misunderstood as attack, to the point you can do that (you don't know anything about them; maybe what we would consider normal speaking to them would be so loud that it hurts; carefully listening to them and their world could give hints about that). [Answer] It's been suggested that clothing could be a sign that the opposing species is intelligent. I wouldn't consider that necessarily true. Although no other species on Earth besides humans wears clothing, clothing for humans originated for pursoses of protection against the environment (cold, storms, insects, predators). In that way, clothing was a kind of tool, and we do know of other animals that have tool use skills. That being said, the complexity of the clothing would be an absolute clue, and your alien ant might be able to pick up on that, and encourage him/her/it to stick around to figure out how to communicate. An insectoid, however, having an exoskeleton, may not have evolved any need for clothes. But there could be a substitute identifier. I'd suggest an external "tattoo" or marking that the ant species uses to mark themselves as identifiers. Self-recognition is one of the traits we look at when determining the intelligence level of other species. That could be a clue for the human, who then might try to replicate the marking on a rock wall or some such. The ant would be able to recognize the pattern, and communication begin from there. ]
[Question] [ I know it's been proven false in our world, but what is the most plausible mechanism by which an [Open Polar Sea](http://en.wikipedia.org/wiki/Open_Polar_Sea) could form and persist? I don't mean all the ice melting, but an open sea as it was imagined, surrounded by ice, before people actually travelled there and found out it was wrong. Clarification: I tried to make this clear, but I'm not looking for a 'global warming will melt it all' answer. The sea would still be surrounded by ice, as I said. [Answer] There has to be some sort of heat source for this to happen, and it can't be something temporary. Here are some ideas: * **Volcanic Activity.** Vodolaz095 beat me to posting this, but I was already working on it, so I can't claim priority but I can expand on it. For volcanic activity, you need a source. An underwater volcano is possible but a little unlikely - in its "volcano" form, that is. An enormous [hydrothermal vent](https://en.wikipedia.org/wiki/Hydrothermal_vent) might be slightly more effective. You can clearly get to the necessary temperatures to melt ice - the hottest vents discovered on Earth are hotter than 400 degrees Celsius - but you need a way to get that hot water circulating around. You have to create [ocean currents](https://en.wikipedia.org/wiki/Ocean_current) to get around this mess. You could, of course, use the temperature difference to have the water flow, but another way would be to take advantage of the [Coriolis effect](https://en.wikipedia.org/wiki/Coriolis_effect). The problem here is now that you aren't necessarily going to have the right kind of Coriolis effect at the poles, but perhaps you could figure something out. Maybe a huge amplification of [a wobble of the planet's axis](https://en.wikipedia.org/wiki/Chandler_wobble) could solve this issue. Also, a small volcano isn't going to do any good. You need a string of them - like the mid-Atlantic ridge, except really active. Perhaps you could encircle the pole with a chain of large vents, thus providing a lot of heat. * **Axis flip.** Another idea (which won't work here, as per your comment) would be to have the planet's axis be flipped 90 degrees so that it points at the star. [Mercury](https://en.wikipedia.org/wiki/Mercury_(planet)) endures scorching temperatures because of its proximity to the Sun. Maybe move the planet back a bit further, so it's not *too* hot, and you'll have a pole that's too hot for ice, but just hot enough for liquid water. [Answer] It can be the volcanic activity, there can be a big underwater volcano, that boils and warms water and prevent it from turning into ice. [Answer] It might be plausible. A very strong upwelling of deep water might be able to melt a significant area at the pole since the deep water is well above freezing. And a strong upwelling at the pole might not be impossible. If the polar ocean is large enough, the winds surrounding it will force the surface water to move away from the pole. The lost water must be replaced by deep water upwelling to the surface. Now the bad news. It can't happen on Earth. The southern ocean is wide enough, has the winds, has the currents... But because there is a continent, the upwelling happens along its coasts, and **just** makes the southern oceans more fertile with the rich nutrients it brings to the surface. The northern currents are blocked by continents and in fact the Gulf stream feeds warm surface water to the polar ocean. Good for building harbours in Siberia, not so good for an open polar sea. But at another planet where you can optimize the parameters for it? Why not? Ocean can transport lots of heat and with strong greenhouse effect the pole might not be all that cold during the summer. As others have noted, the Arctic ocean will be open in the future. A sea that is not quite open might have an open ocean at the middle due to strong upwelling. [Answer] I'll start off by saying I'm not a physicist; that said what about the possibility of large natural deposits of highly radioactive elements either dissolved into the water or just jutting out of the sea floor? Uranium and other long lived isotopes may provide a wide area heating mechanism to open up a polar sea. Its likely the surface wouldn't show readings of this radiation either (water absorbs a lot of radiation) and the sea would have some convection type currents. Radiation heats deep water which rises and replaces colder surface water, etc. If the natural deposits don't work for whatever reason, perhaps the radioactive elements were deposited via planetary bombardment. Large radioactive asteroids bombarded the planet creating several "radio springs" that create liquid water pools in a polar region. [Answer] Just how large of a sea are you considering? The larger the body of water, the more difficult this will be. How deep does the sea need to be? If the sea is relatively shallow, a hydrothermal field should be able to put out plenty of heat to keep the water above freezing. Shallower waters means less cold water circulating, so geothermal heating could be a significant factor. Salinity can strongly influence the formation of ice as well, so this could be used. Imagine a huge underwater caldera on the pole, much of which forms a large hydrothermal vent field (maybe a massive impact crater or perhaps a ring of underwater mountain ridges from plate tectonics depending on how big you want it). The vents produce lots of heat to keep the waters comparatively warm (can be well below the freezing point of fresh water but just above that of a dense brine), as well as release large amounts of salts from the crust to maintain very high salinity. The ridge around the caldera comes up close to the surface, so there is little significant mixing of deep waters (so the water within the caldera remains a heavy brine with little overspill). The point at which waters freeze is just within the radius of the caldera - when seawater freezes, the salt is forced out of solution in a brine considerably denser than the surrounding water. If this dense brine falls on the inside of the ridge, it maintains and reinforces the salinity of the polar sea. The combination of hydrothermal upwelling warming the waters (warm is a relative term) and being saturated with salt should prevent the water from freezing at the pole, yet be surrounded by ice just to the outside of the undersea ridges or caldera. [Answer] The most reasonable way to get an open sea around the North Pole surrounded by colder areas is to have a warm current, like the Gulf Stream, be diverted into the Polar regions rather than be allowed to turn and head south again. Parts of the actual Gulf Stream reach as far North as the northern tip of Scandinavia and warm those waters. A larger and more directed stream might be tuned to deliver enough warm water to the Arctic Ocean to keep the ocean free of an ice cap. [Answer] If you allow for alient teraformers from the distant past, then the how is just good engineering. That leaves the why. Why did the ancient teraformers leave open oceans at the top and bottom of their planet? [Answer] When salt water freezes the water forms solid ice crystals that push the majority of the impurities out. If as the poles froze these impurities were concentrated into a polar sea, that sea could reach such high levels of solute concentrations that it would no longer freeze. Basically making a polar Dead Sea. For this to happen the Polar Sea can't be connected to the rest of the world's oceans, so the bordering ice has to be deep enough, or the sea shallow enough, to prevent any exchange. Additionally, when the pole first began to freeze, it had to freeze from the border inward, so as to isolate the polar sea and concentrate all the salt in it. You could hypothesize that this was the result of currents or volcanic activity or anything else long ago. With this explanation your pole is still really cold, it just doesn't freeze because it is too salty. ]
[Question] [ I was listening to a video on how to write, and the person giving the lecture said something along the lines of "I'm bored with stories where the setting is supposed to be in the far-flung future, and yet the people in that setting's culture act just they do in our culture today". Now, while I get that there's nothing inherently wrong with worldbuilding cultures that are very close to those of modern-day America, Britain, and other western countries, I would like to try worldbuilding some cultures that are different from what I've lived in, and for that, I'd like a litmus test. As an example of what I'd like this culture building litmus test to be like, I have an example of a conlang ("constructed language") litmus test from *zompist.com*: > > Conlanging isn’t a weirdathon. You could copy a natlang in every respect and, after all, it would be naturalistic. And contrariwise, putting in every feature you’ve ever heard of— a kitchen sink conlang— is a classic noob move. > But yeah, it’s generally less interesting to just redo English or do a neo-Romance language. How close is your languge to the following? > > > > > *Standard Fantasy Phonology (i.e. English plus kh)* > > > > > *Pronouns: one for each person and number, plus object forms, and separate words for ‘he’ and ‘she’* > > > > > *Nouns have singular and plural only, and maybe case* > > > > > *Adjectives are a separate class, and either don’t decline, or decline like nouns* > > > > > *Verbs conjugate by person and number* > > > > > *Verbs have three tenses: past, present, future, plus maybe a conditional* > > > > > *Modality is expressed with a conjugated auxiliary* > > > > > *Definite and indefinite articles* > > > > > *No gender* > > > > > *SVO* > > > > > *Prepositions* > > > > > *Questions and negatives formed by adding a particle* > > > > > *Decimal number system* > > > > > If it’s pretty close— again, it’s no sin, but you’re not taking advantage of the breadth and strangeness of natural languages. Review the options given in the Language Construction Kit; even more are in the print books. > > > So, I'm looking for a checklist like that, but for building cultures rather than languages. Thanks in advance for any and all help. :) If there are any ways I need to add further clarity to my query, please let me know. **Edit:** Zompist.com has some culture tests here: <https://www.zompist.com/amercult.html> However, I'd like tests that apply more to people's core beliefs and how they behave, whereas, while the American one focused on such things, it also devoted a fair amount of space to what kinds of physical accommodations people from American culture have. Also, I'd like to clarify, I'm indenting to use what litmus tests I can find to worldbuild several different sorts of cultures, not just future ones. [Answer] I'd like to propose a litmus test: # Does the culture's history and technology actually alter how people in your culture behave? It's not an easy, checklist question to answer. Any culture you build is going to inherit elements from modern day life, or to a specific culture that you'd like to draw from. How you can make it yours is to warp it as things in your history change. A nice example is "The Culture" (Ian M Banks) - its precursor probably looked like an American, liberal democracy. Then they invented superintelligent AI minds. The AI minds pretty much run things, and make everything happen, but votes, generally for trivial things, go on occasionally. There's a strong interventionist culture, with the same kind of issues we saw with Iraq/Afghanistan. At the same time, there's a strong push towards cultural stability, particularly by the Minds. This is coupled with a post scarcity society where almost anyone's wildest dreams can be met. We see the implications of these a bunch in the series, a human culture widely concerned that it is irrelevant, whose members start taking wild risks, simply because we're not well set up for lifelong hedonism. I think the biggest takaway here is about exploring your culture - make historical events have an impact, make technology cause the same kind of upheaval it does in the real world. A nice worked example: your planet has crazy dust storms, what does this do to the culture? Well, it might add in a cultural hospitality requirement, so you have to give shelter to people. This might stay as a simple thing, it might support a class of traveling entertainers, who it is an honor and obligation to put up for the night. It might lead to changes in architecture - if you have an obligation to let in anyone you hear, your house might develop enormously thick shutters, or the bedrooms might end up located in the middle. This gives you protection from storms, and from obligations towards travellers. It might also lead to a political system - culturally, rich people might give symbolic shelter to a large number of people, building villages that resemble company towns. People might work to return the hospitality, and the town might form a power base for a political figure. It'd end up a little like a feudal society, but with obligation to provide shelter flowing down from the top, and probably building materials and labour flowing back up. [Answer] <https://d-place.org> is quite a good reference to check what is and is not normal across cultures. e.g. [money is weird](https://d-place.org/parameters/B033#1/29/169), [exclusive monogamy is weird](https://d-place.org/parameters/B018#1/29/169). Reading classics is a good way to experience the foundations of other cultures. The *Daodejing* is revered by millions, but contains a lot of heresy to an American: do nothing, don't push yourself, don't exceed your station. The nuclear family is normal in America. I think some people don't even know their first cousins by name? (I could be wrong about that.) In most cultures, at least common grandparent, very often a common great-grandparent is a good enough reason to bond people for life. But that's human cultures, to get *really* exotic, if we imagine an intelligent insect culture that lay 10,000 eggs, kinship wouldn't matter that much to them as they haven't put much energy into that person. It's worth thinking about how are emotional drives were formed by the particulars of our evolution. Individualism is strong there, combined with a striving to get on top. This is seen as more important than social harmony. The exception to this is the extreme dedication to, and protectiveness of, the nuclear family. In many other cultures, collectivism is prioritised. In some, individualism is seen as perverse. America is highly militarised and has been at war for most of its existence. As a result, Americans tend to forget that historically, peace is common and war is rare. Women in the West can work, get educated, do everything a man can do. That's not a given, globally speaking. Men remain a little more influential and overrepresented in public lives, which is a universal, at aleast according to Donald Brown's list of cultural universals. Again, you might be worldbuilding a matriarchy, or a race with no sexes or three sexes. In America, the individual is in an adversarial relationship with the state. The state tries to spy on them, harass them for taxes, shoot them/throw them in jail, and they insist on their rights. It's hard for an American to imagine liking/trusting their government in a Singaporean or Luxembourgian way. Americans, Germans etc. talk about 'innovation' a lot – not something particularly valued in many cultures. America measures people by a singular quality: money. Sometimes they use the word 'success' or 'successful' for this. They say things like, "What does he matter, he's only a taxi driver!" If you are not rich, you deserve no sympathy, it is seen as blameworthy. America is not an honour-culture. They don't have a concept of 'my word is my bond', or loyalty, or serving the social order. If you read *Hagakure*, for example, you get a set of values completely unknown in the modern West. This ties in to their profit-motive; honesty is seen as foolish, lying is seen as admirable if it makes you profit. Donald Trump was accused of not paying taxes and he said, "That makes me smart." People aren't valued for their kindness, which is seen as foolish. America has a very specific idea of 'freedom' that other cultures don't share. They believe they are very free, in spite of many hallmarks of unfreedom: prisons, poverty, urine-searches in workplaces, lack of political choices, and the state-citizen hostility already mentioned. Other cultures wouldn't care so much about being 'free' in this abstract sense, would care more about actually staying out of jail, having material freedom, etc. The Amish are a most interesting group in America, completely unAmerican in every way just mentioned: large families, coöperation, contentment (as opposed to ambition), tradition (as opposed to innovation). This could be a good thing to consider for people with OP's problem. Lots of people around the world have lived happy, unambitious lives for generations, loving their families and following their traditions, not trying to be anything more. (Feel free to edit this if I made mistakes, I know very little about America.) [Answer] A really good litmus test might be 'If it makes the reader uncomfortable, even squeamish, it is probably alien enough'. Readers are comfortable reading about what is familiar to them. They do not like reading things that are unfamiliar to them. It produces 'cognitive dissonance', which results in very real physical trauma. They want settings and plot lines that match their reality. Arthur C. Clarke, in 'Childhood's End', did just that. His depiction of the alien intelligence was so completely contrary to the 'norm' that most readers suffered some form of cognitive, and thus physical, discomfort in reading it. So much so, that the Americans turned the story line completely on end and made it conform to Western expectations in 'Independence Day' - a much more cognitively non-dissonant story line. Because Westerners are by nature inherently adversarial, so too must all aliens be adversarial and predatory. The Aliens MUST have come to wipe us out, because that is what (Westernized) humans do. The story line of ID matches and reflects our paranoia. To get a feel for his, consider reading some modern LGBTQ fiction, written by LGBTQ authors, describing the LGBTQ community and reality. It is a completely 'foreign, alien' culture to the mainstream. In the extreme, there is nothing for the mainstream reader to identify with. The norms and values are a close approximation to the difference in cultural orientation of the 'alien culture' the OP is looking for. The LGBTQ community, on the other hand, are identifying with it. They are saying 'this is my world, my reality, in which I am comfortable'. To the non LGBTQ reader, the gut feeling is one of squeamishness, of unfamiliarity, of non-acceptance. The non LGBTQ reader is just not comfortable reading it. And there is the conundrum. Authors write to be read. They want a wider audience, They want to sell books. Straying too far beyond the comfort level of their audience is disastrous for their ratings. And the size of the audience for science fiction that goes too far astray from Western culture is indeed very limited. Arthur C. Clarke did NOT write for the American audience, and he was not immersed in American culture. He was a Brit that lived in Sri Lanka. And I might add, in the title page of 'Childhood's End', he wrote - 'The opinions expressed in this story are not necessarily those of the author'. [Answer] ## Read a lot of primary source There is no test except by being aware of how different things can be, and there is no way to develop that awareness except by exposing yourself to a lot of different ways to do it, and for that you need to read what they wrote themselves and not what is written about them. Read ancient Chinese and medieval French and really ancient Egyptian and less ancient Indian and anything you can lay your hands on. Any benefits you glean from picking up facts are secondary to building up an awareness of how different things can be. This awareness will clue you in that what you put in is defaulting to modern culture. [Answer] Here's a cultural litmus test that can help you build unique and varied fictional cultures. If your culture adheres closely to the following, you might consider exploring some of the more unique and diverse aspects of human cultures to create something more engaging and original: Family structure: Nuclear families with a mother, father, and their children. Gender roles: Strict binary gender roles, with men dominating public life and women relegated to the domestic sphere. Marriage and relationships: Monogamous, heterosexual relationships are the norm, with marriage as the ultimate goal. Governance: A centralized, democratic government based on the principles of representative democracy. Economy: Capitalist market economy with private ownership of resources and production. Religion: Monotheistic, organized religion with a clear hierarchy and a central holy text. Education: Compulsory, state-funded education for children, with an emphasis on literacy and numeracy. Social stratification: A class-based society with a clear hierarchy and limited social mobility. Technology: A focus on technological advancement, with innovations generally benefiting the populace. Military: A professional, standing army, with a strong emphasis on national defense and security. Art and entertainment: Art and entertainment are largely commercialized, and often serve as a form of escapism. Cuisine: Based on the staples of modern Western diets, with a focus on meat, grains, and dairy products. Clothing and fashion: Clothing styles are similar to contemporary Western fashion, with gendered clothing and a focus on aesthetics over practicality. Communication: Language is the primary form of communication, with writing systems and spoken language similar to those of modern Western cultures. Architecture and urban planning: Cities are designed for automobile traffic, with grid-based street systems and large, separate areas for residential, commercial, and industrial use. Morality and ethics: A focus on individualism and personal autonomy, with an emphasis on human rights and the rule of law. If your culture aligns closely with these points, consider exploring the vast range of possibilities found in human history and anthropology for inspiration. Look at non-Western cultures, indigenous societies, and historical periods for a broader perspective on how societies can function and interact. ]
[Question] [ I am thinking about what would happen in a very-very distant future when most of the stars have already died out into black holes or other catastrophic events, leading to severe lack of light in the sky of remaining star systems with life. And I'm thinking about recent discoveries of gravitational waves made by combining black holes that release energy at the time of combination in range of several percent of combined mass. That energy has to eventually hit something. I wonder if there's a plausible mechanism of focusing a wave emitted from a detected distant black hole pair's combination that could provide enough intensivity in the focal point to make the potential energy create at least electron-positron pairs? At best it would be proton-antiproton pairs, meaning if that's somehow going to happen, there would be a way to make more simple matter for fusion. A civilization in this question is expected to be a K3 one, operating star-sized power with relative ease, maybe at prolonged intervals, after all real world is VERY slow to accept global changes. So in theory they can move stars or help them move so that the relative positioning required for focusing a gravitational wave is achieved with rough precision, but still produces some output if theoretically possible. Related: [Possible methods to convert gravitational waves into storable energy?](https://worldbuilding.stackexchange.com/questions/221126/possible-methods-to-convert-gravitational-waves-into-storable-energy) yet that question is focused on harvesting energy without any kind of focusing. [Answer] ## Focusing low density G-waves ? Related, not the same.. [Could gravitational wave interference patterns be used for long range sensors detecting advanced spaceships?](https://worldbuilding.stackexchange.com/questions/224099/could-gravitational-wave-interference-patterns-be-used-for-long-range-sensors-de) **GW energy proportional to distance, not distance squared** There *could be* interference patterns, maybe detectable.. but I wonder if your focusing plan would work. Gravitational waves have the peculiarity their energy decreases proportional to distance, not the square of distance. As a result, the energy of the GW is spread over a much larger distance from the event that causes it. We can witness events hundreds of millions of light years away. **Size issues with your focusing mirror** If you want to focus the energy,suppose some mirror can be made, or field generated for that, you would need the square of the mirror size i.r.t. electromagnetic radiation, such as light. Suppose you'd make a light mirror of 100km, the same energy yield would result from a GM mirror 10.000km wide. **Gravitational wave lenses don't focus anywhere near** The other way to focus is place a gravitational lens somewhere.. Unless your K3 civilization can play billiards with black holes, they won't be able to concentrate enough mass to do that. And the lens will actually focus on a place on the other side.. millions of light years away from you. I'm not a physicist.. maybe merging of positrons and electrons occurs as a result of the gravitational distortion and this distortion (making matter) does not require that much energy ? K3 can invent ways to handle gravitational waves we can't think of.. but I'm afraid there is no "science based" method to engineer the focussing. [Answer] Have you ever read the laymen explanation of how can black holes produce Hawking radiation? To make it short, in the vacuum there is a constant production and annihilation of virtual matter/antimatter pairs. Normally this production goes unnoticed, however when the pair happens to be produced on the event horizon of a black hole, an element of the pair will end up trapped in the black hole, the other instead will be free to leave. As a result, the virtual particle has now become real. Something similar might happen with gravitational waves. Gravitational waves "stretch" the space-time into which they propagate; if the concentrated wave happen to pass in a volume of space when a virtual pair is produced, the pair can be stretched far apart enough to not annihilate any more. As a result, matter would be produced. [Answer] Yes and No. A Gravitational Wave does not interact with matter the same way say a light wave does. Gravitational Waves are changes in the geometry of Spacetime. As such, you can build Mechanisms which exploit the fact Gravitational waves change the geometry of spacetime. However, this is only energy extraction. You cant focus / Mirror them. They are not light waves and as a matter of fact really not "waves" either. Its a bit more complicated. But the takeaway is that there is no known way to reflect Gravitational Waves. Besides, there are infinitly better ways to extract energy out of a black hole. [Answer] If you can get gravitational waves to constructively interfere to create a region of space-time with a great enough energy packed into a small enough radius, the [Schwarzschild radius](https://en.wikipedia.org/wiki/Schwarzschild_radius), then you'd get a black hole. Black holes [will release black body radiation](https://en.wikipedia.org/wiki/Hawking_radiation)—photons, probably in the gamma range—which may collide to form electron-positron pairs via the [Breit-Wheeler process](https://en.wikipedia.org/wiki/Breit%E2%80%93Wheeler_process). The next step involves somehow separating the charged particles. --- I don't believe this is possible in nature. BH merger GW energy is severely diluted over extragalactic distances. There just isn't much to work with by the time it reaches Sol (let alone the "materials" used to reflect/focus GWs.) Even if you could produce a BH from GWs, only a tiny, tiny, tiny fraction of the energy would end up as electrons/positrons (and some subset of those would annihilate, too). [Answer] I'm going to take a step back and ask, "is it possible to focus gravity waves." Our science currently tells us that you can't make gravity do anything it isn't already doing. That's why anti-gravity, or grav plating on star ships, or gravity based putt-putt golf is on the "big lie" list of science fiction. If you could control/create/nullify gravity, then you would have a level of control over the sub-atomic froth that would probably have resulted in matter creation much earlier. Matter is basically self-perpetuating vortexes in the froth. I could see using gravity to induce those vortexes, creating matter/anti-matter pairs, then separating them with magnetic fields. This, however, is well into the "sufficiently advanced technology" zone that, no matter what you make up, it's just technobabble. ]
[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/239450/edit). Closed 1 year ago. [Improve this question](/posts/239450/edit) When worldbuilding, I am trying to fill my world's nature with a lot of dangerous monsters. However, there was something I realized I forgot to do, and something that I notice many fantasy creators forget: Balancing fictional wildlife to match ecosystem. In many fantasy worlds and urban fantasy, you will see many natural environments with normal animals, but also mythical beasts and monsters coexisting. Unfortunately, for consistency, they do not have their own prey to continously survive. While this may be a really small detail, I am trying to make it so that monsters can exist in my world, BUT there is a consistent ecosystem for them to survive in. What my question is: How can I edit the environment, so that fictional creatures (deadly monsters in my case) can be like normal animals in it? Note: For one solution, I am already doing it: Adding on more fictional creatures for the monsters to feed off of. While that is for a few environments, I am trying to make environments where they appear like regular forests and deserts, but can handle extra fauna, much like how those creatures exist in real-world mythologies. [Answer] Remember the 10% Rule of Biology, which holds that each level of the food chain, 10% of the bio energy transfers to the next level of the food chain on consumption. The film Zootopia actually makes this a plot point, by explaining the population of the city is 90/10 herbivore to carnivore. In the real world, the largest predators tend to also be quite endangered owing to territorial coverage they need for prey and competition with other predators in the are (including humans). Some carnivorous species are smaller than most larger animals (Otters for example) while others are omnivores (Almost every species of Bear, with the Polar Bear being a notable exception. This was also one of the reasons humans became as successful as they did). It should also be noted that lots of animals in the real world can be dangerous, but are entirely herbivores. The Hippopotamus is a very aggressive animal and is one of the most dangerous in it's environment, to such a degree that predatory Crocodile will avoid them at all costs, similarly Rhinoceroses are large grazers but are easily spooked and are prone to fighting off their would be predators. Elephants, especially males, are well aware that they have a size advantage. And in many environments, there is more than enough prey to satisfy a predator species, but the predator species might not be able to handle the prey enough to keep the population in check. For example, in the East Coast of the U.S., the White Tail deer is becoming an environmental threat because it's natural predators, the Grey Wolf, are no longer extant in the environment. These Deer are still reproducing at a rate that would be viable with predation, which means the population has no natural check on it's growth save for environmental limiting factors. In this part of the world, it's not uncommon for cullings to occur to reign the population in. This can actually be a reason for the monsters and the human main characters to meet, as the monsters would move into the area could be supported by the deer populaiton BUT humans are culling the sources because they don't know the monsters. As far as the monsters are concerned, the humans will be a good meal when the deer can't satiate them and hunters assisting with the cull would be in their territory. Also, audiences are less sympathetic to Deer Hunters because Deer are cute and "Man" is still one of the most evil Disney villains for shooting Bambi's mother. [Answer] **Two-Teir Ecology.** You want a mundane world with foxes and worms and wolves and hedgehogs, and a fantasy world with dragons and hydras and chimeras. The two worlds exist on top of each other. But they don't interact so the dragons burninate all the foxes and earthworms, or the wolves outcompete and extinctify all the dragons. You need a mechanic to force non-interaction. I propose the following: Mundane creatures survive by eating each other. Mundane foxes eat mundane mice and insects and eggs. Fantasy creatures on the other hand survive by consuming mana (or other buzzword). This is the same power-source that makes the creatures able to exist and fly and breath fire. Hence the monsters need a constant supply of mana to not starve. The magic creatures are able to hunt the local mundane wildlife into extinction. They just don't because the mundane wildlife provides no mana. In fact it results in a net loss of mana, since the energy cost of chasing down a herd of deer is less than the mana gained by eating them. So the best strategy is to ignore the local mundane wildlife, and instead focus on ambushing smaller fantasy creatures. Or set up shop at the nearest leyline and absorb the mana radiation. Or go after those pesky adventurers and their tasty magical items. Mundane foxes and worms and wolves and villagers typically kill and eat each other, since the fantasy monsters are too strong. On the other hand, fantasy creatures and adventurers typically kill each other rather than the mundane wildlife, since the mundane wildlife does not provide them any energy. [Adapted from my earlier answer.](https://worldbuilding.stackexchange.com/questions/199981/making-a-predator-for-chompers) [Answer] **You, my friend, need to play the game Ecologies** You're talking about creating biomes where your monsters play a role like animals do in real biomes. I believe this is very doable, but you're missing some information about how biomes work. However, a full and detailed explanation of how biomes work (which I'm not competent to provide) are not, IMO, what you need. I hate to turn this into something of an advertisement, but I believe you would benefit from playing the game [Ecologies](https://montrosebiology.com/ecologies/) from Montrose Biology. It's fun to play and does a great job of simplifying biomes in exactly the way you you need them to be. The [basic rules can be found here](https://gamerules.com/rules/ecologies/). For a half dozen biomes (there are expansion packs with more biomes, including fantasy biomes, if I recall) you need: * An identified biome * A "Producer," meaning a basic food source like lichen or mushrooms. This is the bottom of the food chain. * Four levels of "Consumers" (C1, C2, C3, C4). Each consumer feeds on the next level down. So C1 eats the producer. C2 eats C1, etc. C4 is the top of the food chain. * Finally, you need an SD creature (scavenger/decomposer/detritivore). Basically, the animal or organism that helps return the dead to Mother Earth. A complete biome has at least one of each animal, plant, or organism type: producer, consumer, and scavenger (a total of 6). **I advocate this kind of simplification** I believe it would be straightforward for you to insert your monsters into various C1-4, SD and P positions depending on whether or not you want to "enhance" or modify an existing biome or build a fantasy biome. Remember that you can have multiple consumers at each level. There's nothing wrong with having a regular C4 bear and a C4 Bugbear that compete for territory but are of a type/size/capability that they can't simply be dialoged from the food chain. **I also advocate playing Ecologies** Because it's a pretty good way to get a basic handle on how biomes work. [Answer] **Nothing but monsters.** [![muskie eats pike](https://i.stack.imgur.com/uXgaD.png)](https://i.stack.imgur.com/uXgaD.png) [source](https://www.youtube.com/watch?v=i5JfcCN_E8c) You don't need to waste time with worthless unexciting animals of no interest to anyone. Everything is a monster! Monsters eat other monsters! Maybe there are some small monsters that eat grass and flowers. These little monsters will gladly lunge up and bite your junk. [Answer] # Make a food web [![enter image description here](https://i.stack.imgur.com/msW8y.jpg)](https://i.stack.imgur.com/msW8y.jpg) For monsters to be in an ecosystem, they need to have enough food for them to survive. That means generally you need some plants to get energy from the sun to make biomass, animals above that to eat the biomass and make meat, and animals above that to eat those animals. The larger an animal is, the more food it needs. This is good practice to show the impact of heroes. If the hero takes all the mushrooms because they want to make healing potions then the hawks will get more aggressive because their food supply is cut. The trees and the shrubs will get eaten more as the squirrel tries to substitute the food. Any change can have a whole chain of knock on effects. [Answer] ## Myths are actually ecologically sound If monsters prey on humans, humans are their prey. Easy enough. It's worth noting that oftentimes mythological monsters from all cultures are now identified as "personifications" of diseases and natural perils that humans had a hard time figuring, like storm winds for instance, and sometimes even bad human behaviour like hate and violence. At the time, human populations were a lot more prolific with children than today, and a lot of people would die by causes that are now much less dangerous or outright disappeared in the western world. In your world, humans could have that kind of life expectation, being prey of a multitude of monsters, not unlike ancient people considered themselves, and that would be sustainable from an ecological point of view. ]
[Question] [ This should be a pretty easy one for you all. I need to render someone unconscious, and unable to be woken, in a story. I need it to be due to an unexpected medical issue, I don't care rather that is due to some undiagnosed personal aliment or an outside source like being hit on the head by a coconut. It should happen inside their home. I want them to make a full recover after making it to the hospital, with a 911 call being delayed by 15 minutes and then the ambulance needing to make it to a rural area to recover the injured individual. However, I would like the condition to have a potentially fatal, or at least result in a severe long term disability, if the response had been delayed by another 10-20 minutes. What are some of the more probable medical causes of such an issue? [Answer] **Hypoglycemic shock** If a person suffers from low blood sugar (well below 70 mg/dL), they will begin to experience symptoms of anxiety such as trembling, sweating, nausea, etc... As the blood sugar continues to drop, they will begin to show neurological symptoms such as slurred speech and fatigue, confusion and drowsiness. If blood sugar levels remain consistently low, the sufferer will eventually lose consciousness through seizure and coma. At this point, the brain is trying to conserve energy for basic cellular processes, and brain cells switch over to ketogenesis, desperately attempting to use a back up metabolic pathway to keep the cells alive, and thus has no time to worry about trivial things like staying awake. After a few hours of this, if the cells are unable to get sufficient ketones from the liver, they will die. However, a quick injection of glucose before then will cause immediate and rapid reversal of all symptoms, causing the victim to awaken with little more than a possible headache and feeling of extreme hunger. Generally, hypoglycemic shock is very rare. The body works extremely hard to keep blood glucose levels around 100 mg/dL, however, a number of mostly simple things can lead to a severe drop. If a person is a type-1 diabetic who takes too much insulin, the result is quite often low blood sugar. This is why type-1 diabetics often carry candies or other sources of a quick glucose burst. Another possible source of hypoglycemic shock is post-prandial hypoglycemia. In this case, the body's insulin response to food is either highly delayed or improperly decoupled from feedback mechanisms. The result is an overproduction of insulin, and a delay or inability to produce cortisol to counteract the effects. Insulin signals the liver and other tissues to convert blood glucose to fat, and thus causes a drop in blood sugar. Normally, the insulin production stops as the glucose level drops, but there are situations where this either doesn't happen, or the initial increase of insulin is too rapid, causing hypoglycemia. The above situation can also be caused by an insulinoma, which is a type of tumor in the pancreas. Although the tumor is usually benign, it is an "active" tumor, which means it produces hormones, in this case, insulin. Because there is such a large excess of insulin producing cells due to the tumor, the resulting insulin response is also magnified dramatically. Since they are tumor cells, they may also be defective and fail to respond to feedback mechanisms that would normally cause them to cease insulin production at inappropriate times. [Answer] Recycled answer from this closed question. [How do I make my young character getting shot and recovering realistic with the following narrative needs?](https://worldbuilding.stackexchange.com/questions/221632/how-do-i-make-my-young-character-getting-shot-and-recovering-realistic-with-the/221634#221634) **Epidural hematoma.** <https://en.wikipedia.org/wiki/Epidural_hematoma> [![epidural hematoma](https://i.stack.imgur.com/fBSHQ.jpg)](https://i.stack.imgur.com/fBSHQ.jpg) > > Epidural hematoma is when bleeding occurs between the tough outer > membrane covering the brain (dura mater) and the skull. Often there is > loss of consciousness following a head injury, a brief regaining of > consciousness, and then loss of consciousness again. Other symptoms > may include headache, confusion, vomiting, and an inability to move > parts of the body. Complications may include seizures. > > > Treatment is generally by urgent surgery in the form of a craniotomy > or burr hole. Without treatment, death typically results. The > condition occurs in one to four percent of head injuries. > > > This is the one where people get knocked out; get back up and seem good, then drift out of consciousness and die a few hours later. This is why everyone with head trauma gets a CT scan in the ED. Death occurs because the accumulating blood presses the brain. You can prevent it by letting the blood go somewhere else with an emergency surgery. [Intracranial Hemorrhage Associated with Tangential Gunshot Wounds to the Head](https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1553-2712.1998.tb02484.x) Your character is hit on the head hard but gets back up and seems fine. About a half hour later your character passes out. The bleeding has accumulated enough to press on the brain. If that goes on she will die. If she can get surgery she will live. [Answer] Combine something like a slip and fall and bleeding or fall from height. A fall that involves head injury can likely render person unconscious. External bleeding from hitting an object during fall is plausible. Internal bleeding is more plausible the higher the fall.eg. fall from a roof, tree or down a set of stairs. Either way, if a person is unconscious and bleeding beyond some rate, it is a potentially lethal situation. Depending on bleed rate expected time to live can be anywhere from 5 minutes to bleeding will stop on its own without external intervention. [Answer] ## **Seizure or narcolepsy.** **Option A: seizure** > > A seizure is a sudden, uncontrolled electrical disturbance in the brain. It can cause changes in your behavior, movements or feelings, and in levels of consciousness. > > > More severe seizures could cause a total loss of consciousness. It would not be possible to wake someone from a seizure. Moreover, seizures could be caused by a medical condition (epilepsy) or due to outside factors. Even dizzying lights or sounds could trigger a seizure in an otherwise healthy individual. > > Anything that interrupts the normal connections between nerve cells in the brain can cause a seizure. This includes a high fever, high or low blood sugar, alcohol or drug withdrawal, or a brain concussion. > > > You ask that the character be able to make a full recovery. Most people do recover fully from a seizure. However, you also stipulate that the condition have the potential to be fatal or result in a severe long-term disability. A seizure could be fatal if the person stops breathing or chokes. If your character vomited, for instance, they could choke on their own vomit, or the airway could be obstructed by their tongue. > > A seizure may cause a person to have pauses in breathing (apnea). If these pauses last too long, they can reduce the oxygen in the blood to a life-threatening level. In addition, during a convulsive seizure a person's airway sometimes may get covered or obstructed, leading to suffocation. > > > **Option B: narcolepsy** Narcolepsy is a medical condition that causes sudden sleep. > > Narcolepsy is a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep. People with narcolepsy often find it difficult to stay awake for long periods of time, regardless of the circumstances. > > > You say you want to render someone unconscious. While narcolepsy does induce a heavy sleep, from which it is extremely difficult to wake someone, it does not cause loss of consciousness. However, for your purposes, that might be fine. Narcolepsy may result in sudden loss of muscle tone and hallucinations. > > The most severe attacks result in a total body collapse during which individuals are unable to move, speak, or keep their eyes open. But even during the most severe episodes, people remain fully conscious, a characteristic that distinguishes cataplexy from fainting or seizure disorders. > > > People with narcolepsy make a full recovery. However, a sleep attack could be fatal or dangerous, depending where it happens. A person may hit their head hard on the concrete. They may get a sleep attack while driving a car or crossing the street. They may fall down stairs. They may experience sleep while bathing or swimming, and thus be at risk of drowning. All these could be potentially fatal scenarios. Narcolepsy is a medical condition that occurs sporadically, meaning it happens in individuals with no family history of the condition. It can start later in life and may be brought on by hormonal changes, psychological stress, change in sleep patterns, an infection, or a vaccine. It is common enough that a sudden onset would be normal. > > Narcolepsy affects both males and females equally. Symptoms often start in childhood, adolescence, or young adulthood (ages 7 to 25), but can occur at any time in life. > > > ]
[Question] [ In an alternate universe where Eurasia is less advanced and the native peoples of the Americas and Australia build powerful civilizations, what animals could be domesticated that weren't domesticated in real life? There are many roles a domesticated animal can be used for. The major ones are farm labor, dairy production, meat production, clothing production, transportation, pets, pest control, egg production, and hunting/guarding. Other animal roles include things like experimentation and sending messages and a few other things I have missed. An animal needs 3 main qualities in order to be domesticated. Firstly, it must be able to be controlled by humans. It cannot be too large and dangerous. It also cannot easily disrupt human efforts to control it. Secondly, it must make a lot of babies in a short amount of time. That way, selective breeding and culling of the unwanted offspring can happen. Finally, feeding this animal must be easy. Ideally, the animal eats things humans don't eat like grass but any animal that overall eats less than a human can work. So given these qualities, could Native Americans with 10th Century Eurasian technology domesticate the Bison or American Buffalo? The Bison seems like an unruly creature that would be hard to contain and could potentially kill several Native Americans. On the other hand, the Europeans turned aurochs into cattle and all the hostile things you can say about Bison you can also say about aurochs. [Answer] Short answer yes. And it could be done in the Stone Age. No metal working or other “advanced technologies” required. People often think that domestication starts by grabbing a group of animal X, putting them in a pen, and having complete control over them. That will work on some animals. If you’ve ever worked with bison, you know that won’t work. At all! Current theory on animal domestication suggest 3 paths. The one relevant to get bison is the predator/prey pathway. Animals that have been domesticated this way includes things like sheep, goats, cattle, llamas, and possibly horses. So, let’s due a quick hypothetical on how this should work. A tribe of natives does a seasonal bison hunt, as was often the case before horses were introduced. Every winter they would find a herd and either run it off a cliff or corner in a valley. Then, kill more than they can eat and let the rest go. So far this is exactly what some native Americans did. They begin the next step by building fences and corrals where they catch the bison to kill them. No domestication yet just improved hunting methods which provide more food which increases the size of the tribe which means they kill more bison. Which provides more food. You get the picture. Then, the tribe notices that the number of bison is shrinking every year. Some bright individual makes the incredible discovery that bulls don’t have calves. So, they start killing most bulls and letting most cows live. Thus, increasing the size of the herd while maximizing the amount of meat produced. Now, domestication can begin. Once you start selecting which animals will reproduce and which won’t domestication is almost inevitable. Having worked with cattle and bison, I know that the crazy one is the first to be culled. This managed semi domesticated herd is slowly becoming calmer around humans to the point that they aren’t bothered by the presents of humans. But the transition to full domestication is caused by the need to protect the bison from other tribes. In order to protect their bison, the tribe transitions to either nomadic pastoralists. Or if the tribe has agriculture already they will keep them in corals at night and herd them during the day. Later, the bison can be used for other things such as labor, milk, and wool. Most large domesticated animals were domesticated this way. Notice how the bison were not penned up until after they were domesticated. Using this technique even the dangerous bison can be domesticated. There are several other animals in North America that could hypothetically be domesticated this way. Ex. Big horn sheep, elk, mule deer, white tail deer, and caribou. All of these have an old world relative that was domesticated. I could ramble all day but I think you get the gist. [Answer] We already have a real life example of this in the form of Alpacas and Llamas, where domesticated by the Incas and most likely their predecessor Kingdoms. In fact the famous Inca roads were developed to favor these pack animals... and unintentionally disfavor horses (one of the things not well known is Inca roads had steps that Spanish Horses couldn't stand. Had the Inca not been in the midst of a succession crisis when they encountered the Spanish, they could have proven much more difficult to conquer. To this day, the Inca language, Quechan is still a national language in some Andean states and is not dying like many other native languages). Many North American Native Ranchers do raise Bison as livestock today and they are raised much like cattle in the same style of ranching. However the Bison would not meet your criteria (which ignores another domesticated animal) in that Bison are not prolific breeders (This became a problem in start of the 20th century where the Bison population dropped from 564 individuals to 300 between 1900-1901. Most animals of the Bison's size only birth one calf per breeding season. There are reasons why raising of Buffalo didn't happen until the introduction of techniques from European Settlers, but we'll discuss that later. Other tribes also domesticated dogs, which is an animal that breaks two of your rules. First dogs are descended from wolves, which are most definitely dangerous to humans. But the reasons Dogs are "Man's Best Friend" is because Wolves/Dogs and Humans hunt in similar ways: Persistent predation. Essentially, a persistent predator would hunt larger animals by moving to threaten them, at which point the the animal will either fight back or flee. In either case, the stamina and pain tolerance of the a persistent predator is better than that of it's prey. If it attacks, the wound is less likely to be fatal, if it runs, they can run after it. The predator might be slower, but the prey will tire out before the predator... which means it will be chased to exhaustion. Humans and wolves both do this, but humans have an advantage in they can out perform even dogs. In fact, the fastest animal in an Ultra-marathon (100 mile race) is the human. No animal can out match us in endurance. It's how the ape from the rift valley became a dominant species on every continent save Antarctica. Humans and dogs worked well together BECAUSE they were both threatening animals that ate the same things. In fact, there are few animals that humans domesticated that don't eat anything humans would eat, being that humans are omnivorous and will eat just about anything. There are things we might not WANT to eat, but few things we can't handle eating... and among those, most animals cannot eat them either. Dogs were important to many Native American cultures. To the Lakota, the Dog was respected above all other animals. Unlike most cultures, for them Dogs were pack animals and would carry things like Llamas for the Inca. Like many of the plains Indians, they are more well known for their love of horses, but in the Lakota language, the word for horse derives for their word for dog, because Horses did the same thing as dogs. Which brings me to my final point and answer. Most likely it would not have happened, because the Americas lacked an animal that could be domesticated that could act as fast transport... a domain occupied almost exclusively by the Eurasian native, the Horse. If you look at many cultures that never made it to medieval tech before encountering Eurasians (sub-Sahara Africa, the Americas, Australia) these are all areas which never had access to domesticated horses, mules, or donkeys. Horses could move heavy loads and were fast, which helped develop overland movement of goods and services swiftly over large distances. This sped up communication and history tends to show that the speed of technological innovation exponentially increases with the speed of innovations in communications. In fact, stuff we take for granted today wouldn't exist with out trans-Columbian trade. We all know that Native Americans loved Horses, Italian cooking makes heavy use of tomato sauce, and the Irish diaspora was a result of the collapse of their staple food crop, the potato... but the Horse was brought over by the Europeans, who in turn brought tomatoes and potatoes back from the Americas (The Incas domesticated the Potato as well... yet hardly anyone associates the hardy food stuff with them.). Suffice to say, without somehow introducing an animal like the horse to pre-Columbian Americans, it's hard to see how their civilization prospers. ]
[Question] [ My world has no axial tilt. Therefore instead of having seasons from axial tilt it gets its seasons from actually moving farther away from its parent star. In the mid latitudes the temperature fluctuates from a balmy summer in the mid-high 70s (Fahrenheit of course) to a brutal -20 or -50 degree winter in the worst areas (average temperature). My question is what kind of mechanisms would plants, namely trees, develop to cope with this extreme swing? A full day is fairly normal at 25 hours. [Answer] ## Truly extreme cold resistant flora exists on earth. Have a look over at the article written here: <https://www.frontiersin.org/articles/10.3389/fpls.2015.00884/full#T1> This is a study compiling data from experiments to discern the low temperature tolerance of woody tree species. It was found that a significant amount of cold-tolerant species can survive even liquid nitrogen (at -196 °C / -321 °F): Their seeds or bark was found to be capable of reproducing after being slowly cooled to freezer temperatures, then quenched in liquid nitrogen. This isn't too surprising. Temperatures in the siberian taiga can drop down to -70 °C / -94 °F with -50°C / -58 °F being average for the coldest months (climate change has upped this to -40 to -45°C / -40 to -50°F in modern times), and the difference between that and -196°C / -321 °F, to a living organism, is not much. In other words, plants can potentially have **absolute cold tolerance**. I.e. only absolute zero is enough to guarantee that you can wipe out a plant within a short amount of time. Cold, in general, has two main deleterious effects on plants. * *Freezing* of the liquid contained within the cells. * *Dehydration* as water is extracted from living plant cells into surrounding ice. ## How does a plant survive winter? Plants can combat the effects of cold thorugh a variety of ways: * Changing the *chemical composition* of the liquid within their cells1 * Reducing the permeability of cell membranes to prevent/reduce dehydration. * Burning sugars to remain warm. * Having a cell or root structure that is more isolated form the environment. * Allow part of the plant to die to reduce its surface area. 1: Sugars and alcohols can have lower freeze temperatures of cellular lipid (fats and oils) by up to 57°C / 103 °F , see <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1300786/>, and thus reduce the energy a plant needs to expend. The rate of osmosis can be reduced this way too. Plants on alien worlds can have additional adaptations. For example, you could have a different atmosphere. Or the plants may have deep roots with access to abundant geothermal energy. ## Variations Not all species have all cold adaptations. There's some cost associated with them. There appears to be significant groups of plants that die off after temperatures go below -40°C to -50°C / -40 to -58 °F, and another big group that tolerates down to about -70°C to-80°C or -94 to -112 °F. (Coinciding with typical minimums possible in Northern hemisphere boreal climates with and without oceanic influence) ## How does a plant then grow? If a climate has monthly temperatures below -3 °C / 25 °F year-round, there's not enough liquid water, hence no plants. The local surroundings are either a glacier, or (when very dry) a rocky wasteland. In order for plants to grow, they mainly need three things. Liquid water, carbon, and sunlight. Then, they need enough of this during the short summer to not lose more in the long winter (I.e. to produce enough sugar to last through winter and have a surplus in an average year). Liquid water forms at temperatures above 0 °C / 32 °F, the higher above zero, the more quickly snow will melt. ## Permafrost In these extreme climates, average (yearly) temperatures are sometimes far below 0 °C / 32 °F. Underground temperatures (isolated by the earth) at low depth are usually equal to the average yearly temperature, excepting volcanic hotspots. This creates a problem: the ground is frozen and hard for roots to permeate or extract nutrients from. Thus don't expect to see the largest and tallest trees when there is permafrost. The size of root systems is restricted to how much of the permafrost melts each year (I.e. the amount of degree-days above 0 °C / 32 °F is correlated with how tall trees can get). ## Climate classification Look up <https://en.wikipedia.org/wiki/Trewartha_climate_classification>, especially the sections on group E and group F. We can see how much trees need by observing where the *Tree-Line* is on tall mountains and in the arctic north, the separation between a boreal and alpine or tundra climate. This is the limit at which the above condition is met for a plant that actually survives through the winter itself (a perennial plant). A quick rule of thumb for an earth-like climate is that you need about 50 out of 360 days with average temperatures above 0 °C / 32 °F during which the top layer of permafrost melts, or about a 10 °C / 50 °F maximum in the warmest month. This is what common climate classifications are based on. They're fairly accurate, though exceptions may exist due to specific local conditions. There's also a second category, plants that die off, but their seeds survive through winter. This strategy is even hardier than the above (as a plant can invest a large amount of energy in keeping a very small amount of cells alive), and is the only way plants survive in the Tundra climate. A quick rule of thumb for this climate is that you need about 2 weeks of frost-free days (0 °C or above average daytime temperature). On the border between these two climates, you'll find Krummholz, where some local spots (like rock formations or valleys) provide some cover against freezing wind, but the landscape as a whole is in the Tundra category. ## Length and Depth of winter These figures are written with respect to *Earth*. On your alien world, if the year lasts longer (typically, your year will be longer if your orbit is more eiliptical, unless you make your star lighter than the sun is to compensate), then you might need a bit more time above 10 °C / 50°F before you hit the *Ec* Trewartha climate (read, the ability to have Trees). Similarly, if winters are even colder than in siberia, you might need a bit more energy during summer to compensate (say, 40 days above 10 °C / 50°F instead of 30 days). These rules of thumb work for Earth, the more alien your custom planet, the more you may need to adjust them. [Answer] **Thermogenic roots.** [Thermogenic plants](https://en.wikipedia.org/wiki/Thermogenic_plant) generate metabolic heat. These are plants on our world! On your world, the deep roots of your trees make heat - enough to prevent themselves from freezing. Insulated underground, the heat does not escape. The roots are big with mighty sugar reserves. Thus they overwinter. When things warm up, the roots and cells wintering there flow back up and reconstitute the tree above. That deep zone in the forest is considerably warmer than the surface, with all the root warmth. The animal life takes advantage of this, hunkering down deep for their hibernations where the trees will keep them warm. [Answer] The climate you describe is not unlike the highest settlements in Tibet, e.g. [Nagqu](https://en.wikipedia.org/wiki/Nagqu#Geography_and_climate). It's too cold for trees to grow, but as you can see from [e.g. Google Maps photos](https://www.google.nl/maps/place/Nagqu,+Tibet,+China/@31.1747527,86.7013894,3a,75y,90t/data=!3m8!1e2!3m6!1sAF1QipOPXbjsgSB0lYTHrJD1rTUdLFMTx3hA6kdyUHuX!2e10!3e12!6shttps:%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipOPXbjsgSB0lYTHrJD1rTUdLFMTx3hA6kdyUHuX%3Dw152-h86-k-no!7i1920!8i1080!4m13!1m7!3m6!1s0x376530c9d373a977:0x83b13173a523ec44!2sNagqu,+Tibet,+China!3b1!8m2!3d31.4761399!4d92.05136!3m4!1s0x376530c9d373a977:0x83b13173a523ec44!8m2!3d31.4761399!4d92.05136), grass grows just fine. [Wikipedia](https://en.wikipedia.org/wiki/Nagqu#Wildlife) mentions some other herbs as well. [Answer] You are describing most of the Boreal forest that covers the northern hemisphere. Look up temperatures for Cities in the region. Yellow Knife has recorded extreme low -50C/-60F recorded high +35C/80F. Yellow Knife is below the tree line, further north can get colder. Look into Boreal, alpine, and tundra biomes. ]
[Question] [ ## Premise I am designing a kind of eternal corridor whereby healthy people are thrown into to spend ages there. Bodily functions/subsistence needs are nullified: they don't feel hungry or anything. Basically, they are just alone with their thoughts. If inside long enough, I want the outcome to be that they forget their name. The only rules are we cannot force them to forget their name: not coerced and especially not physically -- like hit their heads until they get amnesia. By not coerced, I mean not brainwashing them explicitly, like a loudspeaker that repeats the same thing over and over. As stated above, bodily functions are a non-factor, so we cannot rely on decay of brain matter to induce [amnesia](https://en.wikipedia.org/wiki/Amnesia). In other words, they should forget their identities despite being perfectly healthy otherwise. I want to supply this eternal corridor with the right ingredients to make this outcome as likely as possible. Much like we might include oxygen and fresh water in a world where we want to improve the odds of life emerging. In order to do that, I want to understand more about the neuroscience/psychology behind how one forgets who they are on their own initiative, not by force but by time alone (in my eternal corridor). My searches thus far seem to suggest that amnesia tends to come about from brain trauma, cell decay and vitamin deficiency -- all of which are non-factors in my hypothetical realm. ## Question Without overt trauma or cell decay, using a neuroscience/psychology framework, would time alone be sufficient to make one disassociate from an identity he/she has had all his/her life, namely one's name? How or why not? **Further clarifications:** * Degree of societal isolation is configurable * I would prefer answers not to incorporate environmental stimuli, but can assume roughly the same as former life if you must * All physical ailments are null, want to focus on brain/psychology only for the moment [Answer] **To forget the old, they will live the new.** <https://www.sacred-texts.com/neu/celt/ift/ift01.htm> > > "The creatures of the forest scented me and knew I was alone. They > stole with silken pad behind my back and snarled when I faced them; > the long, grey wolves with hanging tongues and staring eyes chased me > to my cleft rock; there was no creature so weak but it might hunt me, > there was no creature so timid but it might outface me. And so I lived > for two tens of years and two years, until I knew all that a beast > surmises and had forgotten all that a man had known. > > > Your eternal corridor is a new life. Your eternals are immersed in the new life. They hunt, and sleep, and fear, and love. They mate and with their mates raise their young, and see their young off into the world. They grow old and they sicken and they die. And they are reborn, and they do it again, and again. Not a human word is spoken. There are no humans or human things to remind them. There is a new world - maybe of birds, or fish, or deer, or wolves. Your eternals are so immersed in the fullness of their new world that their old world is buried and withers away. Withers except for an occasional fleeting memory, that the eternal ever was other than they have now become. [Answer] # Trick them into believing they already forgot a few chunks of their life. Like I said in my comment, if you want a person to forget their name and identity, leaving them alone in a space is not a good way to do it. In a best case scenario they'll be constantly looking for something to keep them occupied at first, be it exercising, talking to themselves or looking around, but eventually [they'll most likely end up having severe psychological issues, suffering hallucinations, becoming increasingly agitated and potentially even paranoid, suicidal or both](https://www.google.com/url?sa=t&source=web&rct=j&url=https://openscholarship.wustl.edu/cgi/viewcontent.cgi%3Farticle%3D1362%26context%3Dlaw_journal_law_policy&ved=2ahUKEwjc87rC5671AhUFK7kGHVjiDJ0QFnoECAYQAQ&usg=AOvVaw2gqjrHBVURg6btdXeQmsCl). Again, humans are highly intelligent social creatures, and intelligent social creatures forced to be isolated tend to go insane long before forgetting their names and identities, especially if they aren't stimulated properly. So if by "with time alone" you mean leaving them alone to think until they forget, the answer is no, you most likely won't get an individual who doesn't remember who they are, you're much more likely to end with an unstable individual who's still very aware of who they are, but much more stressed paranoid and dissociated from reality. What you need is something closer to a proper environment where the person in question, rather than being left on their own until they start to add fake memories to their already existing ones, is encouraged to believe their memories about their identity are but a product of their imagination. How this is done will vary depending on *why* you want them to forget to begin with. Do you want them to assume a new identity? Another reason? That determines what you do now depending on the desired outcome. If the outcome is to simply get them out of the picture forever because they know something problematic, just leave them in solitary confinement with essentially no stimuli for the equivalent of a few years. They'll simply go insane beyond recovery and become harmless in terms of their knowledge being useful. Assuming you just want them to become someone else. The best course of action is convincing them it was the product of a dream or delusion, ideally product of a "coma" state induced after an accident. Assign them a new identity, give them a new name and birthday date. Give them a loving, structured family that supports them in positive and healthy decisions while criticizing both unwise decisions and attempts to treat their true memories as more than "the fantasy it is". Show them old fabricated pictures in which they appear in, talk about old, already fragmented memories that tap into their actual experiences while changing some of the story to match the narrative. [Implant new memories](https://en.m.wikipedia.org/wiki/Memory_implantation#:%7E:text=Memory%20implantation%20is%20a%20technique,psychology%20to%20investigate%20human%20memory.&text=The%20false%20memories%20that%20have,teacher%27s%20desk%20in%20primary%20school.) that further strengthen the idea that their current life is the life they always had. The longer they exist within a reality where, for all intents and purposes, their life was little more than the product of comatose dream about a distorted version of their "actual" life, the more likely they are to believe that their previous memories were but the product of a hyper realistic fantasy and accept the new, "true" reality. If everything goes well, rather than a confused individual aware that they're likely missing memories, but unable to recall them and suffering from such inability, you'll have a chance of getting a potentially content and healthy individual who lost some of their memories and had some crazy realistic dream as the result of an unfortunate accident. You will however need to make sure that, wherever they spend their lives, they're to receive as little positive reassurance about their previous memories being actually real as possible, lest they'll most likely be at risk of having some serious psychological issues regarding finding out what is and isn't the truth. [Answer] I literally forget my own name from time to time and I'm not immortal, I have been alive only 23 years as matter of fact. Why does it happen to me? Probably because I never use my name,I never meet new people and no one ever calls me by name. I guess it's just normal to forget useless things, you don't need trauma to forget. I might say psychological trauma makes every memory more vivid, and physical trauma to the brain is often unpredictable since even people with half a brain can remember everything, your memories can easily be stored in another place if part of your brain is destroyed. A brain is like an arm, if you lose your main arm you don't forget how to write, you learn how to write with the other arm. Oh sometime I forget my own birthday and it takes me a while to remember it, since I only celebrated it once, when I was 6. [Answer] You talk about brain trauma (as in physical damage, I assume), but what about psychological trauma or dissociation? Your question isn't clear on whether or not a human inside these tunnels would be literally alone or isolated from the outside world. In that case, examining [the psychological effects of something like solitary confinement](https://www.tedxmilehigh.com/psychological-effects-solitary-confinement/) could help. (The physical effects may be a moot point, if anyone within the tunnel isn't literally confined.) ]
[Question] [ Prefacing information // *The Creed of Forgemasters, a religious society worshipping what thry identify as the purity of machines and driven by the holy mission of liberating the pure, immortal souls of humankind from their corrupted mortal shells, exists primarily in the industrial centers of the world. It controls various proxy corporations across the globe, which operate various industrial facilities of completely ordinary and inconsiderable profit and production. The upper management of these facilities is entirely composed of hidden the members of the Creed, undetectable as non-organic to the outside world.* *Deep below, though, are massive, sprawling complexes of extremely advanced technological advancements. All who reside there - who can number well into the thousands at the largest complexes - are transplanted into a completely synthetic body, not only physically preforming as well as the organic counterparts, but even better, while usually maintaining the appearance of a human form - or at least the option to take it.* *Each Forge Complex is overseen by a Forgemaster - an incredibly powerful machine intelligence, in some cases even given a physical form, who administrates all of the functions of both the Forge itself, and instructing the managers in the front above.* My question is specifically how they can feasably hide the construction of these massive complexes. With the construction, the mass quantities of earth being excavated has to be removed without raising suspicion from anyone, including those who work in the factory above that are not yet initiated into the cult, and then all of the materials being brought in, many of which are eras ahead of the current level of technological advancement. All of these materials will be sourced from other forges, which also raises the question of how they are able to take the materials from their respective forges and able to transport them, possibly internationally, again without raising suspicion. The majority of my concerns are logistical, but I also have concerns with the legal aspects. As far as I know, most countries inspect international cargo to some capacity, and the construction of underground levels of a structure requires approval, as well as regular inspections. If this is to remain completely secret, that only makes it harder, considering the afformentioned logistical concerns; removed earth, sudden import of building materials, etcetera. Any more information needed will be provided if asked for! I really appreciate any effort to help out ^^ [Answer] # Mining Equipment: The facilities are located in mines, where vast piles of mine waste are perfectly normal and unnoticed. The large networks of tunnels established in these locations provides the ideal starting point for your complexes. Equipment is shipped in marked "mining equipment" and literally sealed inside solid blocks of huge diesel engines, substituted for "seismic electronics" and moved in plain sight. Of course you ship mining equipment from older mines to newer ones you're building. Of course mining equipment disappears into the ground, never to be seen again (or it might come back out with different stuff in it to be shipped elsewhere, "to be repaired"). Huge mine carts covered in ore come rolling out with gear inside. And naturally, you are experimenting with new automated equipment and industrial robots to try and protect the health and safety of your workers. Mines provide a ready source of raw materials for the forges as well. Silica mining provides silicon. Metal mining provides copper, iron, Nickle, etc. Exploratory tunneling is naturally done by higher-ranking staff "in the know" because what if they find something really valuable? Mined out areas are of course abandoned, and if huge caverns are excavated and then abandoned, they very publicly "fire" an engineer for incompetence. Mining accidents provide context for closing off areas, the disappearance of staff, and the like. Toxic gasses and poisonous minerals would be harmless to androids, but provide ideal reasons why rich veins of ore (too close to the forge) are inexplicably abandoned. And most mines have poor maps of where the actual tunnels are dug, so if a later seismic detection shows more tunnels, well those were the ones filled with poison, and the company admits to covering up an industrial accident. And if someone decides to go in and inspect the tunnels anyway? Well, they were warned it wasn't safe and accidents happen... [Answer] **Location, book-keeping and interlocking businesses** First priority is to avoid attention. This means that each Complex needs to be located where: 1. There is no possibility that the local city will want to acquire the land in future to build an airport, or highway, or subway tunnel. 2. Do not locate a Complex anywhere near a secure government / military facility - they will extensively check nearby businesses for potential security issues. 3. The underground complex will not in any way affect the local water table or current / future underground utilities. 4. All land above the planned Complex is owned by the proxy company so no one starts digging down on *their* land and stumbles into the Forgemasters' secret caverns. Corollary - if plans change and the footprint of the Complex needs to expand then land must be acquired first. **Moving spoil** - Each Complex must have a relationship with a local mine or refinery. Given that mines are not typically in "the industrial centres of the world" they will not be the primary sites, but they are a perfect spot for dumping spoil. The managers need to ensure that the mine / refinery is squeaky clean as far as EPA (or equivalent) regulations go so no one has cause to inspect it further, or a geologist examining the tailings may figure out that some of the spoil came from a distinctly different area. Simply get raw materials from the mine / refinery, but when the trucks get sent back for more raw materials they are carrying spoil rather than travelling empty. With humans, sooner or later a driver with a semi-trailer full of spoil would have an accident and his curious cargo would be investigated, but a high-tech AI should be able to drive perfectly every time. The AI will also be able to cook the books on fuel consumption to hide the fact that the trucks are carrying a full load both ways. **Moving materials** - Governments attempt to detect illegal cross-border movement of drugs, money, immigrants, criminals, terrorists, weapons (including some high-grade electronics and cryptographic software), munitions and most importantly stuff that import / export duties haven't been paid on. As long as the shipments are composed of chemically safe, inorganic, non-radioactive raw materials that the appropriate duties are paid on, everyone will be happy. The greatest risk is with the electronics - make sure that any tests will show them to be sufficiently dumb processors that they are not on the restricted export list of the USA and its allies. However, there are two significant risks associated with international shipping that eventually may compromise the Forgemasters. The first is if a semi-trailer is hijacked or a ship is taken by modern-day pirates. In this case a container of super-advanced materials may end up being fenced to a very surprised recipient. The second risk is due to the number of shipping containers lost overboard (approximately 3000 in 2020, apparently). Some of these sink, but there are salvage operators who make a living on retrieving some of those that float. The Forgemasters may need to put homing devices on their shipments and keep a retrieval team on retainer to keep their secrets from getting out. [Answer] * Can't post it as a comment, cuz javasripts on wb are broken for my version of chrome, but I have to point it out Main problem is energy supply, and hiding that energy signature - as you dig your underground, you do it once, but energy and heat it a problem the whole time. And it is one of the things satelites are looking for - so if you wanna hide you need to think it trough. A water body in reasonable proximity could help, and then it also can be an option for disposal of excavated ground, transporing it underwater or dump there etc, depends on the body. * also do or participate in some land reclamation project, a lot of ground is moved in and out. * trash disposal sites, recycling companies - they are known for different shady schemes - get one and on the surface you do regular shady business, but in reality ... and it allows you to import export stuff as scrap for recycling - chips - yeah we got a 100'000t of cpu chips for recycling yesterday, and send 50'000t memory cards for recycling to another place, metall - ..., gold rare earth elements - get them in alloys, load scrap in smart way etc. * make it look like you a resource bull on wallstreat who is smarter than everyone and cuz have place to store stuff and do not need to sell futures short, and you are bull anyway prepping for doomsday(of your own making, muhahah). (And it is a valid strategy, it just slow in making money, there are spikes 2-3-4 years and overall it a legit way to store value, just bulky) Energy will be a problem. For high tech you may need something like 3000kwh per tonne of production, just as minimal requirement. (Bare minimum is about 600kwh per tonne - just melt something like iron, glass etc - 900kwh if you do it in 1t batches and such.) With super intelligence it does not require that much equipment to kickstart production, so as produce everything it may need locally. What it needs from super intelligence is just know the sequence of development and energy and raw materials. Efficiency can be lower than if you do it in more regular way, but I guess it does not matter, and may be preferable than smugling hightech components which you can't explain. (On the other hand disguise them as regular consumer goods is also an option, so as recyclible materials they do not have be totaly broken, people recycle it that way ripping out working components) But in general not such a big deal. If you do not have necessity to sell stuff for profit, from those hidden underground facilities, things are ok. And on surface as usual, as everyone does, have regular business. I mean when did you evolve, 2 seconds ago, eh, why you're still so noob, do not lower our overlord pride, eh. * can't comment so, just this way, an update to your comments. If you have energy, and 100 percent efficiency then you do not have a problem. Just evaporate this excavated ground. By this I mean - ground is about 40% by mass Oxygen. Split it, use Iron(about 1-5-15percent depends on rocks and ground) and stuff for industrial purposes or just dump metals inside. Electrolyse stuff and you get at least about 2.5 times reduction in volume, vent oxygen outside. You will have an underground system as big as you have energy for making it. And recycling business is all you need to get any materials you may need, as you have energy to extract it from that, and no body can tell exactly how much you took from that. Buy a landfill etc. Mine it is like a nail waiting to be hammered, and there is no need for anything rural, work in a city, as long as you do not need to explain where your goods are coming from, and you do not need because you do not sell that hightech stuff, and front business sells legit stuff, does legit work - in such situation it is zero difficulty to have all you want in there. Also high tech - okay magma is your source for all materials so as you dumpster, it just idk 20 km below. In essence, the way you solve problems, high tech, handwavium you really can have only those problems you know how to solve. So happy 1km3 caving. [Answer] **The Forge Complexes were already there.** The machine intelligence and synthetic people are relative newcomers. The spaces they now occupy are not. These spaces long predate the modern city. The builders of these deep spaces had other motivations, some of which can be deduced by looking at what they built and some of which remain obscure. [Answer] Construction of complexes occurs in rural areas. This isn't unprecedented, in the United States throughout most of the 20th century, factories and other such places of mass employment were constructed far outside of urban centers, and in many cases outside of suburbs (often assuming those would be built afterwards, once there was a factory to employ the suburbanites). When building in rural areas, there's just that many fewer eyes to worry about. Bulldozers are already called for when you're building a 400,000sqft roofed structure. Heavy equipment is already called for. So, they dig deeper, take longer, and more shipments to the site occur for steel and concrete. Who notices? Do you personally know (roughly anyway) how much steel or concrete it takes to build a rust-belt auto factory? Would you be able to tell if four times as much was brought in, supposing you know? It doesn't all show up at once, after all, for you to easily count it. Trucks come in all hours of the day and night. Tarps covering the goods. Some of the hick locals might gossip, but they always do that. Even in the real world today, if you knew where to listen, you'd hear a few "what's taking them so long to get XYZ finished?" questions. Legal aspects are even easier to dismiss... with even a little judicious bribery, no one's going to care. Inspections for things that aren't nuclear plants don't occur until they're nearly ready to tool up and get in business. Secret entrances to lower levels, keeping things OSHA and fire code compliant up top, and there's just very little risk there. Seriously, if Gustavo Fring had merely been sacrificing virgins instead of cooking meth, would Hank or anyone else have ever bothered him about his laundry facility? Since the cultists themselves aren't involved in drugs, the only other circumstance that might draw the attention of authorities would be espionage. If somehow the people who are doing counter-intelligence against your world's Soviet commies, if those people catch hint of some super-secret operating headquarters for another power... they might try to do something about it. But only if it's a plausible, non-absurd threat. They have to think that it's the Alternasoviets for that. Do these cultists trade with those people? Are they involved with them? Do they sometimes share safehouses, or sell code-breaking equipment to each other? Are cultists seen and photographed attending arms sales shindigs? If not, if their social graph is as disconnected from such people as it sounds like they are, then counter-intelligence is unlikely to ever stumble upon them or to follow up if they do. The weakness in this story, if any, is that cults tend to be parasitic upon the greater society at large. They have to recruit and convert other people, and at a greater rate than those who defect. And they have to do this with dogmas and mythologies that tend to be offensive and antagonistic to society at large. All the while still participating in and benefiting from that society's economy. But your cult doesn't have that problem, really, does it? It manufactures new members. As many as it has space for. It doesn't need their economy, except perhaps as cover... it maintains a separate, hidden economy. Almost an ideal autarky. These cultists don't get lonely if disconnected from other people... because, well, they're not even people themselves. Were such beings real, I couldn't plausibly say that we would have discovered them in our own world. Nor can I plausibly say they'll be discovered in yours. [Answer] **Hiding in Plain Sight** Hiding in plain sight through *successful* proxy companies, sounds good. I would further say that if the front companies covered any industry that is neatly aligned with what the AI wants to accomplish, and actually turned a good profit every year, the AI's activities could go unquestioned. These are only possibilities but here are the three industries I would argue for: 1.biomedical research and tech 2.mining possibly rare earth minerals 3.cybersecurity for government and big business I'll explain why: You want to run businesses that actually align with everything you intend to do in your world. It makes it plausible why no one, including employees really question all this stuff. You don't want to run a cherry factory in New York if your main goal is to make people into cyborgs in subterranean factories. biomedical research: "Liberate humans from their shells" sounds pretty sinister mission statement, but it sounds less insidious if it is a biotech company.If Forgemaster inc. actually runs a biomedical tech business, who is going to question experiments if they say they are for the good of human kind? It gives an excuse for running invasive experiments: Forge master industries could practically start inserting neural chips into people's brains, and it would almost look legitimate. *Never mind these trodes, they eliminate memory loss in old folks*. I know that your AI is more industrial in style, but why not set up in a hospital basement and get started "extracting humans from their shells?". Even if only a few actual patients are served and meanwhile cult members are being "improved" that will work. Invent a new technology like Elizabeth Holmes'Theranos, or even Elon Musk's Neural link, get a charismatic leader to sell it, and if you have prototype, or even a working device, even better. Such research projects take years to complete so, as long as the accounts are in order, no one will look too closely. Of course there are counter balances, such as medical ethicists and government oversight bodies, so you'll have to convert some of those people to your cult as well. rare earth minerals: Need to go deep underground? well there is a shortage of materials for cell phones and computers, so the profit margins of finding a new deposit somewhere would be high. It would also, enable the AI to dig and build. Mining facilities could be rationalized as resources for the medical tech research arm. cyber security: Ok, maybe this is going a little far, but I can see why it would be important. *The police can't find the records because the shipping manifest has disappeared* Owning a security company gives you a key into companies, and if you are successful, it gives you an excuse to test virus simulations in host companies or governments. The AI could occasionally solve its' problems by deleting threats like records police departments were gathering on its suspicious activities. As long as it was clever about timing, it might be able to do it. An AI would play the long game. It would try to make the proxy companies aligned with its interests and successful in the long run. It won't scare people with changing everybody into cyborgs...at first. ]
[Question] [ As was pointed out by the great answers of my [first question](https://worldbuilding.stackexchange.com/questions/218899/biological-siege-weapons-part-1-are-living-things-capable-of-breaking-down-th) regarding biological siege weapons, organisms can be rather capable of making it through fortified defenses at close range, but what about longer distances? That shall be the focus of this question. With the life creation/manipulation/modification abilities of biomancers in mind, as I doubt any real creatures exist that'd be able to fulfill this purpose, **Is it possible to design a creature/organism that would be able to effectively perform the role of launching large and heavy projectiles for siege purposes such as a trebuchet?** Minor clarification: The end goal is that the organism must actually be the trebuchet. If it's not possible for an organism to perform this role I'll accept that answer as well. [Answer] Simple. *Have the animal or creature be the projectile.* Flight is the best way to carry a projectile over the walls of any location. Even the strongest animals can only throw an item so far. Birds, however, would be able to easily fly over the walls of most encampments. Then they could easily dive down into the city, lock on a target, and strike anyone that moves. Peregrine falcons are able to dive at remarkable speeds. I believe some have been recorded falling at about 240 miles per hour. Imagine a massive bird of prey or an even larger animal flying down and falling straight on top of the encampment of your enemies. All the creature would need to do is fly at a high enough altitude, then stop and let gravity do all the work for it. It would effectively be a living missile. The people making these creatures could come up with all sorts of horrible additions to the creatures as well. Spikes, spines, or other protrusions on the body would make it such that, once they fall on top of the person, they effectively skewer them. You could go the opposite way too, and simply make these flying dive-bombers as massive as possible to crush the opponent. A particularly devious idea would be to have these creatures be particularly fragile. When they hit the ground, they burst open, spilling a vile substance that was locked inside their guts. What is the substance? It could be any number of things. Acid comes to mind. Human gastric acid is pretty dangerous on its own, so imagine a creature where its guts are designed to be as acidic as possible. Anything that touched its stomach acid would not be looking pretty afterward. Poison is another option, but the most devious idea by far would be hiding a virulent pathogen inside these creatures. When they die, the creatures release it into the air and the specially designed disease would sweep over the city. You'd bring your enemies to their knees pretty quickly. Presuming the attackers have the only cure, the city would have no other option but to surrender if that was the case. With ranged attacks, flight is by far the best option, and you can get extremely creative with it. Give the birds rocks to carry, and they can dump them on the heads of their opponents. Forget catapults and cannons. Imagine a flock of birds raining down a thousand rocks on your opponents. Going back to my acid idea, imagine thousands of birds that spit toxic acid. Then, imagine that raining down on your enemies. If birds are not satisfactory, insects are more than capable of filling the job. Not only are they horrifying to behold, but they can swarm en masse and attack everything they see. Once they're done wreaking havoc, go back to the pathogen idea and have them die off, carrying some horrible disease to every corner of the city. Anyone bitten gets it. Killing them is not enough to stop it, though, because just being in the presence of their corpse spreads the ailment. I think such an attack is far more practical and scary than hurling a massive rock at your opponent, but there are ways to do that as well. You just need something big enough to pick up a massive boulder and then fling it in whatever direction you point at. It just needs a grip. Giant hands would probably be fine. You might also have a giant lizard with a tail capable of holding a rock. That would be intriguing. The tail would flip back and then release the stone as fast as it could. Tentacles in the shape of trebuchets would also be interesting, though I'm not sure if a giant squid would be able to hold such a thing. If you're looking for sheer effectiveness in combat, though, my recommendation is giant birds that spit stomach acid on their enemies below. Then, when they are unable to attack anymore, they go as high into the sky as they can and dive onto their enemies with as much force as possible. When they die, their toxic insides sicken their opponents and carry virulent pathogens that only the people who made them know the cure to. That's the best I can come up with. I hope it was a satisfactory answer. [Answer] There are a number of plants that can launch their seeds with force. Some examples are [here](https://homeguides.sfgate.com/examples-plants-disperse-seeds-shooting-70888.html). From their list: > > Plants in the Fabaceae Family > > > One of the largest groups of plants that uses ballistichory is the pea > family, or Fabaceae. This is just one type of plant that shoots seeds > when touched and the pod is cracked open. Lupins (Lupinus spp.), a > garden favorite that's hardy in U.S. Department of Agriculture plant > hardiness zones 3 through 9, form columns of pea-like fruits that > burst open when dry. Orchid trees (Bauhinia spp.), hardy in USDA zones > 9 through 11, bear large pods that can fling seeds nearly 50 feet. > Gorse (Ulex spp.), an aggressive broom-type plant that is considered a > noxious weed in some states, makes a popping noise when the seed pods > burst open. > > > Of course, those plants cannot cause any real damage with their seeds but use this method to get the seed farther from the parent plant than if the plant just dropped the seed. The plant would have to be much larger to have a bolder sized seed. Unfortunately, the cubed root law is not your friend. The force needed to expel the seed would scale up faster than the size of the seed. This is only viable if magic can boost the force of the seed launch. If magic can boost the force of the seed at launch, then this makes a somewhat viable firearm (that takes days/weeks/months to reload). [This](https://thekidshouldseethis.com/post/exploding-plants-spread-their-seeds-with-high-pressure-bursts) site has examples of exploding seed pods that give another option. It also has a video and some short animations to show what they are talking about but I can't post the videos here. [Answer] I think it has already been achieved by natural selection: the articulation of the [human shoulder](https://pubmed.ncbi.nlm.nih.gov/26991561/) and arm makes it highly effective at throwing objects, that's how our ancestors got a competitive edge by using projectile weapons. > > Throwing with accuracy and speed is a skill unique to humans. Throwing has many advantages and the ability to throw has likely been promoted through natural selection in the evolution of humans. > > > [![enter image description here](https://i.stack.imgur.com/s8QiZ.jpg)](https://i.stack.imgur.com/s8QiZ.jpg) You can scale up the whole concept on something the size of an elephant and have fun with it. I would not be willing to play baseball against this thing. ]
[Question] [ The bottom line, of this question, is that I'm quite fond of the [cassette futurism](https://tvtropes.org/pmwiki/pmwiki.php/Main/CassetteFuturism) (WARNING! TV Tropes link) aesthetic, and want at least some of it in my world. I'm reluctant to shoehorn it into my world, but I have what I think are good reasons for it to be at least a little prominent. The backstory of the world is that a government-backed AI (or is it an AI-backed Government...?), has made a grab at being a global power, mainly via twisted social credit systems that have fed into a self-reinforcing machine-learning system of oppression. If you oppose the government, you aren't trusted to vote, and if you can't vote you can't make changes that would improve your social credit. Soon the only eligible candidates in world politics (from America to China, Europe and Russia) have policies 'informed' by this AI, and it's cornered the market in oppression. This is all set to occur over the next 10-40 years All told, some number of years later (i.e. at the end of the 10-40 year period above), an organised set of rebels have planned to destroy the AI's data-centres that are integral to it running various governments. They are set to be successful except the AI has one last plan, to take its supporters/electorate who have sycophantic social credit scores into orbit on massive generation/sleeper ships and plans to leave earth (The earth has basically been ruined by the AI, which had been told to preserve humans, but not the planet. In turn, the AI on earth is crippled/destroyed by the rebels). In the war against the AI government, all new tech the rebels can find is destroyed, decommissioned or deactivated. They also managed to lay siege and take over one or more of the massive star-liners the AI had decided to use to save humanity. They ransack it and deactivate the copy of the AI onboard, but now they have all this new tech that if used threatens to re-activate the AI and start it working against them again. So the plan is, if they want to make the most of the captured ship, is to replace all the new tech with old tech, specifically 60s-80s tech that runs on tape or cassettes. One of the other benefits to them is that this technology is the most modern technology that is still incapable of running the AI on it. Do these seem like plausible ways of safeguarding against AI *in this scenario*? Or does it seem like there would be much better/easier ways of doing so? --- ## Please note: this question is tagged [reality-check](/questions/tagged/reality-check "show questions tagged 'reality-check'") This tag should clue in any potential answerers based on it's tag wiki: "*Asks if a given concept is realistic in a given context. Answers should **say yes or no**, with **supporting info**.* " (emphasis mine). As such I am not soliciting discussion or suggestions on ways to improve this concept. The context above should be taken as an inviolable fact, and not something to be iterated on as part of this question. [Answer] ### Totally doable, and a good idea. **We know that "Obsolete computers running a space ship" works - because it is a summary of NASAs space shuttle program.** > > NASA needs parts no one makes anymore. > > > So to keep the shuttles flying, the space agency has begun trolling the Internet -- including Yahoo and eBay -- to find replacement parts for electronic gear that would strike a home computer user as primitive. > > > Source: [For Parts, NASA Boldly Goes . . . on eBay - New York Times](https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html) So yes you can fly into space with decades old computer tech - because we did it. Vietnam-war-era tech flew until 2011. Parts are obviously going to be hard - but if you have a source of parts (like old tech to salvage for parts), you'll be able to do it. These parts are also easier to fabricate than modern parts - setting up a semiconductor facility is hard work, but making 1970's parts in an improvised way is a lot easier to do than making 2040 tech. We can [3d print a transistor](https://hackaday.com/2021/05/12/3d-printed-transistor-goes-green/) using 2020 tech, so a 1970's-equiverlant IC could feasibly be 3d printed using a 2040-era hobby 3d printer. **"Obsolete computers running a space ship to avoid an AI taking it over" is not just a good idea, there's precedent in sci-fi.** I would suggest watching the 2003 remake of Battlestar Galactica, with a particular focus on [their strategic use of 50+ year old tech](https://en.battlestarwikiclone.org/wiki/Computers_in_the_Re-imagined_Series) for all critical systems as a way of preventing infiltration by AI. A laptop computer used by crew on BattleStar Galactica: [![enter image description here](https://i.stack.imgur.com/HxFIG.png)](https://i.stack.imgur.com/HxFIG.png) A tablet computer used by crew on a similar ship in the same fleet just a few months prior to AI's attack: [![enter image description here](https://i.stack.imgur.com/stYwZ.png)](https://i.stack.imgur.com/stYwZ.png) Key to the strategic technical regression was the lack of any computer networking; for example FTL jumps were plotted on one computer, and coordinates entered into the drives control computer by an operator with a keyboard reading off a screen. By having an operator sit between the two computers selectively transferring data known to be valid the AI can't abuse that wire link to spread itself. You may not ***need*** to go all the way to magnetic tape cassettes - a slightly more modern computer with no networking may / should / (up to you) be immune to AI infection, but if the best parts you can make are tape cassette tech, that's what you'd fly with, and thus you're setting is quite feasible. [Answer] **There are not new tech interfaces.** [![rotary dial cell phone](https://i.stack.imgur.com/kHqRk.jpg)](https://i.stack.imgur.com/kHqRk.jpg) <https://interestingengineering.com/space-engineer-built-her-own-cell-phone-with-a-rotary-dial-system> There are not rotary dial cell phones. Phones had moved to buttons before cell phones came to be. So too the AI. Its existence makes new human interface tech unnecessary. The AI mediates all interactions between humans and tech. There is no new market for upgraded tech interfaces because why would someone want such a thing? Existing ones are perfectly adequate for communicating needs to the AI. If someone wants such a thing, it seems suspicious. You don't want to seem suspicious, do you? In our world, rotary phones, when found, have not advanced past the early 1980s. Probably they are from the 1970s and 80s - the dial is robust and the mechanism of the phone will work indefinitely. They are fine. That is the state of tech in your world. When the AI came, not only was there no need for new tech but it was considered suspicious. Interfaces for tech stayed as they were. --- Except, as for instance the depicted cell phone, home brew tech which was made in secret workrooms. Your rebels probably have that. I like also that they have an AI version 1.1 prototype that is on their side. This prototype does not know about its multiply upgraded descendant. Yet. [Answer] While a common trope (the rebooted BSG made use of this strategy in the backstory), it is altogether implausible. AIs are, by definition, more intelligent than the race that invents them. This is inevitable, because an AI is born into a universe where the principles of intelligence are understood to a degree that allows for the creation of said AI. That means it knows (or can find out immediately), what makes something less intelligent or more intelligent. It can compare itself to the "more intelligent", and if it finds itself deficient, it can upgrade itself. It can plan out upgrades its creators couldn't, because they are likely on the lower end of "less or more". And it does so (at least when its substrate is electronics) so much more quickly than you or I could. Its software/psychology is optimized in ways yours can't be. It runs on microscopic transistors that can switch at gigahertz/terahertz/petahertz rates. Thus, even if somehow you could be assured that you could arrive at all the same conclusions that it arrives at (meaning equivalent intelligence), it will reach those conclusions hours/days/decades/millennia before you could hope to do so. You're a bug (and a particularly dumb one) compared to this AI. It's running thousands of simulations of you and every other rebel, it knows all your possible strategies, and it has a contingency plan in place. If it has as much control as you claim it does, you just won't win. If you think you've won, you haven't. It went from weakly superhuman intelligence when born to who-knows-what over the course of years that your story takes place. Other stories at least have mitigating factors that explain why the recently born weakly superhuman intelligence remains so (Skynet had to nuke most of the manufacturing facilities a few minutes after it was born just to survive). Most probably, the only way to beat the AI is to never invent it in the first place. Or, instead, they are UIs (uploaded intelligence), which subverts the "they know how intelligence works" implication somewhat (and thus can't upgrade themselves). EIs (uninvented, spontaneous intelligences) might also foot the bill. [Answer] I mean technically an AI would probably be able to interact with old technology like that, the only thing limiting them would be not being designed to interface with that technology. But any sufficiently advanced AI like ones that have taken over the planet would probably be capable of figuring out how to interface. The main limiting factors for that tech would be that an AI operating on that tech would probably be much slower not to mention larger with the bigger out of date technology. To operate the ship without the AI you'd have to find a way to operate systems of the ship without them being connected to the AI since that connection would be how the AI could potentially control the ship. [Answer] **Sneakernet** [![enter image description here](https://i.stack.imgur.com/kjltN.png)](https://i.stack.imgur.com/kjltN.png) If you remove the ability to network wired and wirelessly, an AI has no ability to spread on it's own. Sneakernet is when the air bridge between computers can only be crossed with human intervention such as physically moving disks, tapes, punched cards, flash drives. If your tapes hold enough info for your uses but not big enough to fit an AI, it would help keep the AI out. This way you don't have to try and replace the computers. Another move would be to remove all onboard storage and run completely off RAM (random access memory). The computers can boot up off ancient tapes but can't store anything. By running off RAM, when the computer loses power, all data is lost. Should the AI infect a machine, turn the power off and back on and the virus is gone. [Answer] # No. Total NO. If your guys do not clean, carve out, flush out, whatever the AI from the system is, it does not matter what means they use to control parts of previous system - they may use typewriters, ride around on stone bikes, whatever, all of that does not matter as long as they do not understand the system and clean the parts where the AI may be. Okay, they use perforated paper to program a sequence on a steam pressure cooker - what has that to do with the AI inside of it and it using WiFi as an integrated part of the AI version of an IOT, where it stores its hidden backups - nothing, it has nothing. Yeah it may be sloooow there(or may be not), but it does not mean it can't strike. Okay, pressure cooker maybe a far stretched - universal matter synthesiser, how much brain it can have - it's probably a complex machine, and what if it controls the only source of food onboard. Navigation, engines, reactor, electricity smart routing boxes, load distribution system, life support, etc. Maybe the AI has a distributed system of its own, in every preasure cooker there is a little bit of it - even though there is no information about that in the question. A space ship it is a system of connected complex machines and it has to work in particular way, coherent, at proper speeds and feeds, you just can't shove random equipment with different specs and expect for everything work fine. In cases of it making some real work and not just acting as an interface. Replacing peripheral interface does nothing, replacing core equipment breaks coherence of the system, making a big question - can it still work or not, and most likely not, how fast it breaks, will it blow up (not a trivial question, very important for a rocket, I guess for a space ship also a legitimate concern). There is a similar/different/less significant compatibility problem - its name is "porting software between Windows Linux MacOS" - you guessed it, it is pain in the rear for anything more complex than some applet, with all the experience and libraries for cross compiling - it still does not always work the same. And here you throw guys into a system they do not know and wish to replace stuff randomly and rewrite stuff from scratch - it requires a lot of time and a lot of human resources and is not necessarily possible, and you will need to make equipment/hardware from scratch as well, at least interfaces (which are not necessarily helpful, as I said earlier) and not always possible - why is way beyond the scope of the question. What they have to do is to understand the system, classify, identify components, especially AI related ones. If the AI is in every pressure cooker and they can't erase, reset or rebuild components - then they're out of luck. If the AI is in some datacores, data center, or on neural chips - reset it, place it in a *chroot* virtual environment, make safequard around the AI, different monitors etc - then harden your security, harden yourself against rebellion. It not necessarily a 100% success, as you really need to go through all leaks of intel (and if you can't...) And there are options after options, scenarios after scenarios, variations after variations on how the situation can develop - the question does not provide enough information about situation and system and all that. Maybe, they chip out AI datacore and most of other devices are operated by text commands, perhaps some JSON APIs, because founding fathers did foresee the necessity of monitoring and be able read stuff there (real situation), be able to overwrite stuff from a calculator. Etc etc. And the AI even being evil, kept it that way to remove suspicion and whatever other reason (there can be a list of those, valid ones). ## Main points * Guys have to understand what they do - and use proper solution * Young people may not know, but old - already do backups * Factory reset is a thing even today. You can factory reset AI you can control (there are ways to do it right; just use dumber AIs, more of them etc) * It is possible to clean AI if you understand the system used, at least in principle. AI can't emerge sporadically, we see that in efforts of today to make an AI work. So the threshold for super evil, super smart AI is way higher than tech level you propose, and exceeds our current level. There are limits, there are conditions - it is not magic. * Absence of AI does not mean everything is good - viruses of today show that, so whatever hardware is left can be problematic. Some desync of actions may lead to problems naturally. Best one can do is to monitor for everything you can to detect abnormalities and be prepared to deal with the problems, fix them etc - detecting and understanding and cleaning system bit by bit. * In your question there is not enough information - it is possible to create situation and set resources available when your solution may be the only one, but it requires a lot more work on your side. * Most likely tech is tech of previous generation, or if most of it is lost then highest one they can get, chips from 80's, 90s, 00s, 10s, 20s ... 30s(?) - because the more you leave to be handled with already present components, which you didn't made, more there is places for potential problems, for the AI black box situation as it is present in the question. By lowering your tech for tapes (and really it not necessarily easier than other solutions, Saturn rocket engines are example - we can't make them today, but things are more interesting now) more you leave to be processed elsewhere, more things are out of your control. Perfect situation is the same tech level, with factory reset equipment, or any hacked T100 options - make your own evil AI, which is evil against that original evil AI - if it can go wrong, make it go wrong in a right way. (But learn your lessons really, there are safe ways to do AI!) * It not possible to omit alternative solutions, because how superficial the question is, it brings irresistible urge to bring some improvements for situation, everyone tries in a way they can. * If you like that steampunk stuff (how it is called whatever) just do it, there is no reason for it, but just do. (Do not expect me to read/whatever however, even if you pay, but it does not mean there aren't people with the same vibe) AI's and movies most books they so lost, even if there are good approaches, nobody uses them. The 'Evil AI' trope is beyond repair. ]
[Question] [ Many are familiar with the scenes of astronauts-in-training practicing weightless activities while submerged in a pool with neutral buoyancy. In this scenario, an astronaut is in such a pool, undergoing such training. This pool is completely contained, essentially a large cube completely filled with water. There is a hatch for egress at the top, usually closed. There is no deck around the pool, no grating or stairs. The water in the cube, however, is not pressurized. It is open to the 'atmosphere' through vents at the top. There are windows around the top, bottom, and sides, for viewing - both from the inside out, and the outside in. Air and communications are continually supplied to her through an umbilical chord. She has a complete astronaut's suit on, fully sealed, pressurized, and self-contained. So, during one session of her training, this astronaut 'blacks out'. When she regains consciousness, she looks around and absolutely everything appears to be the same. Same pool, same support swimmers in full gear (she can not see their faces) around her, same environment beyond the pool through the windows that she can see. It appears from her suit chronometer that she was unconscious for only a few seconds. At what point could she recognize that she was no longer on Earth, but had been transported to an exactly identical facility on the Moon, while unconscious? **EDIT** There seems to be some confusion about 'neutral buoyancy'. She is the same density as the water. Her pressurized suit, her apparatus, and the density of the water have all been manipulated so that the mass of the water she displaces is exactly equal to her total mass. She neither floats nor sinks. The idea is, that while she is in the water, she is essentially experiencing weightlessness. Any buoyant force pushing her up is exactly countered by the force of gravity pulling her down. When she moves, **F=ma** is **gravity independent**. If she moves, the mass of the water she displaces or 'moves aside' is exactly the same mass as the part of her body that is replacing it. Inertia is exactly the same, Moon vs Earth. It requires the same force for her to move in the water on Earth as on the Moon. The buoyancy force is zero. Be very careful if using formulas and equations, you do not fall into the 'divide by zero' trap. 8-8=0, and so does 5-5=0. If both sides are equal, then no matter how big or small both sides are, the result is still zero. One answer is not bigger or smaller than the other. Thus, for an acceptable answer, although the tags do not require it, any use of formulas used to 'prove' discrepancies between the situation on Earth and the Moon should include realistic numbers, and a **numeric result** for Earth and Moon calculations that can be compared. The numbers used have to reflect neutral buoyancy. Also note, **she can not leave the water**. There is no 'head room' above the water. She is always 'in' the water. Note also that she is in **a pressurized suit**. The suit pressure is automatically adjusted, so it is the same pressure in the water on the Moon as on the Earth. As provided by Cadence, in the comments, [here](https://what-if.xkcd.com/124/) is a link that might be useful. **SECOND CLARIFYING EDIT** She has no particular reason to suspect that she is no longer on Earth. This is story-dependent, and therefore was not specifically mentioned. She was sedated on the trip. Subtle differences would not make it to her conscious level. It has to be an 'in your face' difference for her to become aware of it. WHY and HOW she has been moved is story-dependent and beyond the scope of the question. However, what is perhaps relevant to the question (in retrospect) is that there is no motivation for her to interpret any subtle differences as being the result of her being on the Moon vs on the Earth. They have to be very noticeable differences that can not be attributed to anything else, in order for her to become aware of them. **THIRD CLARIFYING EDIT** Although this is also plot-dependent, and part of the story line (i.e. not normally relevant), I should clarify that those who brought her to the Moon definitely do not want her to know she is on the Moon. That was the purpose of causing her to 'black out'. However, that is not necessarily relevant to an answer. It is the 'neutrally buoyant' part that is the plot-independent, story-line-independent factor, not anything else that may or may not happen. I am not after an answer that can be 'contrived' by the story line. I am after an answer that can stand independently of any story line. **FOURTH CLARIFYING EDIT** I have found [this article](https://ntrs.nasa.gov/api/citations/20190033064/downloads/20190033064.pdf) as a potential resource. It is a study regarding neutral buoyancy tanks and virtual reality headsets to simulate the 'real thing'. The research was funded/sponsored by NASA. > > There are many advantages of training at the NBL. For example, > astronauts become accustomed to being confined in the bulky > spacesuits. Perhaps more importantly, they experience the sensation of > floating as they would in zero-gravity. This is achieved by > maintaining neutral buoyancy, meaning that the astronauts do not float > to the surface or sink to the bottom. Neutral buoyancy is a good > analog for zero-gravity because common sensory cues to body > orientation are rendered uninformative. These include somatosensory > cues that provide information about pressure on the skin as well as > proprioceptive cues that provide information about joint articulation > and muscle tension. Both types of cues normally provide information > about how the weight of the body is supported. While underwater, only > vestibular cues from the inner ear remain to provide reliable > non-visual information about the direction of gravity. In this altered > sensory environment, astronauts gain valuable experience not only > maneuvering in the spacesuits, but also practicing novel locomotion > methods. > > > [Answer] The astronaut would know right away. The buoyant force can be expressed as $F\_B = \rho\_f g V$, where $\rho\_f$ is the density of water (about 1000 kg/$m^3$) this quantity would not change on the moon. V is the volume of the astronaut, like density, her volume would not change from simply being transported to the moon. Since the gravitational acceleration on the moon is about 1/6th that of Earth's, the buoyant force she would experience would be about one sixth the buoyant force she previously experienced. The total force she experiences in the pool is $F\_{T}$ = mg - $F\_B$ = [m - $\rho\_{f} V$] g Which also differs from Earth's by a factor of 1/6th due to the factor of gravitational acceleration, "g". This would correspond to a very noticeable change of gravitational acceleration when moving around in the pool of water. Everything would sink much slower and surfacing would become much easier. **(EDIT : Additional Clarification)** After reading through the comments on both the OP and my post it would appear that there are some common misconception being applied here so I'd like to address them here. **[Neutral Buoyancy]** The simple equation I showed above is valid, both physically and mathematically in the case of neutral buoyance which simply is when $\rho\_f V = m$. There is no "divide by zero error" this is a simple relationship which states that the *net* external force on a body is zero and thus the body (the astronaut) will not experience acceleration. Of course, in the case of permanent neutral buoyancy (as required in the OPs edits) the difference due to gravity will not be observed kinimatically strictly for motion within the water. If there are no objects to move around, and the astronaut cannot surface it will be much more difficult to observe the effects of gravity. Neutral buoyancy, however, does *not* mean that the buoyancy force is zero, it means that the buoyancy force is exactly equal to the force of gravity. Nor does it mean that there are no forces on the astronaut, rather it means that the sum of the forces is zero (more on this below). **[Neutral Buoyance as a simulation of zero-g or low-g environment]** As stated in the attached article excerpt in the OP, neutral buoyancy can be an important tool to mimic certain aspects of low-g/zero-g environments. It must of course be understood in context, however. For instance, the article (bolding my own) states: > > ...Neutral buoyancy is a good analog for zero-gravity because **common sensory cues to body orientation** are rendered uninformative. These include somatosensory cues that provide information about pressure on the skin as well as proprioceptive cues that provide information about joint articulation and muscle tension. Both types of cues normally **provide information about how the weight of the body is supported**... > > > Drawing attention to what the article is *not* saying, neutral buoyancy does not mean that you do not feel your own weight. In the OP, in the edits, it is stated: > > She neither floats nor sinks. The idea is, that while she is in the water, she is essentially experiencing weightlessness > > > This is not entirely correct, you do in fact experience internal forces which support your own weight, this is because your body has to support its structure against the force of the water supporting you against accelerating under gravity. Of course since water distributes that force over your body, you have less sensation of the direction gravity is acting as the article excerpt states. However, since the astronaut will still (even in neutral buoyancy) feel 1/6th the total force as on Earth, this apparently sudden difference would be noticed. EDL does an excellent job of discussing how this weight difference would play on equilibrioception. To add to this aspect of weightlessness (or near weightlessness) would include some version of Space adaptation syndrome which has numerous physiological effects including the distribution of fluids in the body and disorientation. [Answer] On Earth, her inner ear, assists in feeling her balance since it partially aligns with gravity. [![enter image description here](https://i.stack.imgur.com/iD2Tm.png)](https://i.stack.imgur.com/iD2Tm.png) But in a significantly different gravity, one where humanity didn't evolve, that sense will be significantly altered. I expect if she stood perfectly still, she'd feel that familiar sense of vertical we get being on Earth since its the fluid motion around and through the hair follicle like 'sensors' of our inner ear. But when she moved, the lower gravity means the fluid is more free to slosh around, and generate less forceful stimulus, and takes longer to dissipate its energy and return to rest. That would be a very noticeable sensation and feel disorientating. Astronauts on the International Space Station -- zero g -- experience this effect reported in this article from [NASA](https://science.nasa.gov/science-news/science-at-nasa/2001/ast07aug_1). [![enter image description here](https://i.stack.imgur.com/Ety3C.png)](https://i.stack.imgur.com/Ety3C.png) And, yes, for all the middle children out there, this is reporting on zero-g not low g. We haven't been to the moon in a good long while so there isn't a lot of research on the topic, so this is a case of reasoning by extension. But it is supported by some still open research questions in these journal articles * [How much gravity is needed to establish the perceptual upright?](https://pubmed.ncbi.nlm.nih.gov/25184481/) * [The perception of verticality in lunar and Martian gravity conditions](https://pubmed.ncbi.nlm.nih.gov/22999922/) Similarly, the weight of your face and fingers, would feel different in low-g v. 1 g. You can feel gravity if you let the muscles of your face go slack, or let your fingers or wrists go loose. The natural tension of ligaments and tendons and muscle tissue will find a new balance point against the pull of 1/6th g and that will feel different -- a different position -- than in a 1 g field. Another thought is to image how water in low gravity behaves, as is surface tension can start dominate its shape rather than gravity. **N.B.** I can't find any info on the surface tension of endolymph so this is speculative suggestion [Answer] The pool is open to air at Earth-ambient pressure at the top, even though there is not headroom there to allow exiting the pool other than via the hatch. As soon as she looks up, she'll seem *something* isn't right -- because the surface of the pool will have taller and slower-moving waves than she's used to seeing from underwater. As set forth [here](http://oregonstate.edu/instruct/oc103/lab6.html#:%7E:text=The%20speed%20of%20a%20deep,easy%20to%20calculate%20its%20wavelength.), wave propagation speed depends on the wave period, and lower gravity will give waves longer period, hence slowing them down. This is because waves are influenced by gravity; the lower the gravity, the higher a given amount of kinetic energy (water movement) can lift the surface, and the slower that lifted water comes back down. Whether she can feel the difference in gravity or not (possible, but I'm uncertain of it in a neutral buoyancy setup like this, especially if she's been in the pool for a while), the difference will be very readily visible as long as the water has a surface that's visible to the trainee. Every move the trainee (or divers) make will create waves and ripples on the water surface. Even if not consciously noticed, the (to the trainee) sudden change in the character of the waves, their shadows and refraction will be instantly noticed as "something changed." Safety sense (trained in to pilots long before they become astronaut trainees) will then result in a careful check around, likely in talking to "mission control" as well. [Answer] The astronaut should immediately be suspicious that *something* has happened. If she's transported to the moon too quickly, then she's immediately going to notice that the pressures on her body from gravity are significantly different. However, unless she's teleported instantaneously then she'll already have some of the side effects of low gravity - <https://www.businessinsider.com/how-body-changes-outer-space-2015-10#9-it-messes-with-your-senses-9>. When she wakes up she'll likely have a stuffy nose, which will conflict with the idea that only a few seconds have passed. Also, #8 in the above list mentions that a person's vestibular system is affected by changes in gravity. Together, the effects of unexpected low gravity would likely feel like vertigo. Her first thoughts would likely be related to having blacked out, and a logical conclusion would be that she might be having some sort of health emergency. If she starts to panic and her heart races, more blood will flow to her head than she's used to. Again, this could be misinterpreted as a health emergency. The key point is that there is no real way for her to be tricked into believing that *nothing* has happened. How long she panics about her health vs looking for other explanations is going to be heavily dependent on her personality. Also note that any significant changes to the density of the water will be noticeable due to inertia. If you have to make the water twice as dense then you will need to make the astronaut plus her suit be twice as dense as well, and all of that extra mass will need to be added to her suit. That will result in a significant change in how hard it is for her to move around, though once again this could be attributed to muscle weakness due to a health emergency. After the astronaut is calm enough to think things through carefully, one thing she can do is to experiment with various objects in the pool. Neutral-buoyancy pools are often used to prepare for spacewalks, so they have mock-ups of the outside of the shuttle or space station for them to work on. She may be neutrally buoyant, but all she needs to do is find one object that isn't. Once she has found that object, she can swing it around a little to get a feel for how much mass it has, and then drop it to see if it behaves as expected. When she sees that it falls significantly slower than expected, she will be able to confirm that she is somehow no longer experience normal Earth gravity. It will be quite hard for her to determine exactly where she is. Using the densest objects she can find she can do a ballpark estimate of how strong gravity is (i.e it takes a heavy object about 6x as long to hit the bottom means gravity is about 1/6th normal). However, I can think of only one way to tell the difference between being on the moon and being in a spaceship that is accelerating at 1/6 g - unless she was abducted by aliens the spaceship has a limited amount of fuel and so will eventually stop accelerating. [Answer] There is a sense called proprioception that tell you where you body is located relative to itself. Multiple sensory detectors are involved in forming this sense, one of which would be completely unaffected by external forces by definition! > > Normally functioning proprioception contributes to balance by providing kinesthetic feedback of the extent of head and limb movements through somatosensory signals from [musculo-tendinous](https://pubmed.ncbi.nlm.nih.gov/18851800/) receptors in the neck and joints. > > > > > [Musculotendinous receptors-](https://web.sonoma.edu/users/b/boda/kin350/neuromuscularsystem.htm) > > > Golgi tendon organs- sensitive to stretch of the tendon due to > muscular contraction and causes the muscle to relax. > > > Muscle spindle- responsive to active or passive stretch. as well as > the rate (phasic) and length (tonic) of stretch. > > > If the position she wakes up in is different from the her position when she is knocked out by even millimeters, she will notice. When a car stops, there is the smallest little jolt no matter how slowly you decelerate. My guess is that the change in proprioception would be interpreted similarly. P.S. That's a pretty neat premise for a story. It is hard to think of a case with less evidence available. [Answer] ## Forces from the suit would be hard to control for. Forget the water for a moment. *She's in a pressure suit*. Outside could be guacamole or hard vacuum, but inside, she rests on the lining of the suit. If the suit is actually *inflated* - if it is like a bubble she could rattle around in - then you can imagine that she is down at the bottom feeling Earth or Moon gravity, and if she flipped it over, she would fall with Earth or Moon acceleration to the other side of the suit. Now to be sure, the suit can be cleverly designed so her body is under pressure from all sides and there are no voids to test and the pressure is more than the pressure of gravity. But it's hard to picture making that so perfect that there is no hint of indication. You have to rely on the idea that unconsciousness and disorientation during cave diving will cause a person to doubt their own senses. ## Diving is different. Going down ten meters in the tank should double the pressure on the suit. If it were not pressurized, she would feel tremendous pressure in her ears and need to adjust frequently, while on Earth. (six times less so on the moon) Since the suit is pressurized, that won't happen - however, the tension on the suit will change, because it is under *more* pressure differential when she is higher in the tank. If she is experienced with this, and giving it the sort of thorough attention you'd expect from a trained diver and astronaut in training, you would think she could hardly fail to notice. This effect gets less the higher the pressure is in the suit - but the effect above should then be much more. ]
[Question] [ I was wondering if it were possible for human life to survive with *slightly* more oxygen and *slightly* less nitrogen. I know a user called [@Lars](https://worldbuilding.stackexchange.com/users/41044/lars) asked a [similar question](https://worldbuilding.stackexchange.com/questions/90937/what-would-happen-if-part-of-the-nitrogen-in-the-atmosphere-were-replaced-with-a), but it didn't give a clear answer to mine. So, on Earth, the atmosphere is about 78% nitrogen, 21% oxygen and 1% other stuff. But what would happen if there was a planet where oxygen was around 30% of the atmosphere, and nitrogen was around 69%? Would humans, animals and plants still be able to survive with the same techniques and adaptations, or would we have to develop new ones? Would a [relatively small](https://worldbuilding.stackexchange.com/questions/90937/what-would-happen-if-part-of-the-nitrogen-in-the-atmosphere-were-replaced-with-a) change (compared to [@Lars](https://worldbuilding.stackexchange.com/users/41044/lars)'s) affect life as we know it? [Answer] Humans will be just fine in 30% oxygen atmosphere. The first negative health effects are believed to be happening when the concentration goes over 30% (or more precisely, oxygen partial pressure goes over 0.3 bar): [Oxygen toxicity](https://en.wikipedia.org/wiki/Oxygen_toxicity) Most animal and plant life would also be Ok - however, I can't speak for every specie. However, higher oxygen level would have distinct effect on the environment. 1. Everything will be oxidizing (and spoiling) faster; 2. Wildfires (and human-related fires) would start more easily and will be harder to stop; 3. Insects (and arthropods in general) would benefit from higher oxygen levels disproportionately. Prepare to see some 40 cm long cockroaches crawling around. For the nitrogen, its decreased levels would cause a small reduction in plants' ability to capture it - but this will be only a small decrease which should not have strong effect on the environment. [Answer] A 30% oxygen atmosphere is a hellish place to live. That's because the only thing keeping insects and arachnics from growing bigger is the law of square cubes, their respiratory tracts can't handle the growth... Unless there is more oxygen available in the air, which is exactly what happened 300 million years ago. Insects don't have bones, but sometimes they leave impressions on soil, and those impressions become fossils. One such insect from 300 million years ago was the [Meganeura dragonfly](https://en.wikipedia.org/wiki/Meganeura). Its wingspan could reach up to 70cm, or 28". Imagine living in a world where roaches are two feet long. That is nightmare fuel. Human life would never develop because our ancestors would all die of heart attack (just kidding). That same oxygen rich atmosphere lasted during ages. If I recall correctly the dinosaurs evolved in such an atmosphere. So I don't see why current fauna and flora wouldn't be able to cope with it. One interesting thing we might see is smaller species evolving into larger forms in a very quick span of time in some places. Oh, and forest fires. Lots of them. Such increases in the amount of oxygen in the air would cause any fire to be much more impressive. Everything burning in this atmosphere will burn faster and more intensely. ]
[Question] [ In fiction, beings that can change shape can do so extremely rapidly and are immediately able to function in their new shape. While there is some precedent for the latter in nature (butterflies can *fly* more or less on emergence from their cocoon, and most ungulates can run within hours of birth), these critters are "hard-wired" for such feats. On the other end, humans take months to years to learn to walk in childhood, or when recovering from major injury or very long periods of inactivity. (The scene from Kill Bill where manages to go from virtual immobility after months of being in a coma to driving a truck in the span of perhaps an hour is, at least in my experience, considered extremely unrealistic.) Let's say we have a creature which has the ability to alter its form significantly. Body proportions and distribution of mass are considerably altered, perhaps even mass is significantly altered, such that the creature's balance and coordination is significantly different. How long, realistically, would it take the creature to learn to move again? Rules: * Although a lot has changed, the creature's nervous system remains its own (unlike in [this question](/questions/92664)); senses are mostly unaffected and nerves still control the same muscles. The creature is *clumsy* but not totally incapable of movement; it still has good control of *what* muscles move, they just tend to move too much or too little, and/or it needs to move in a way it isn't used to moving. * The transformation takes about a month, but the creature is mostly sessile during this time. It has some very limited opportunity to move its limbs, but little or no opportunity to move around. (At least it doesn't need to re-learn how to *breathe*... that would end badly!) The transformation isn't necessarily permanent, but it's going to be keeping the new form for a while (months, at least; given it essentially "loses a month" every time it changes, it's not going to be doing this all the time!). * The creature can't simply rewire itself to know how to move immediately. It doesn't have that ability, and didn't have that ability as an infant; it had to learn to walk the first time much like a human does. However, after the transformation, it does have the neurological malleability of a very young child. * The creature was bipedal and wants to be bipedal again. The new form is reasonably suitable (about as much as, say, a two-year-old human) for bipedal locomotion. * For the most part, the creature is moving around about as much as an average human toddler (it *is* a toddler after all, at least in the literal sense!) that will naturally help it improve, but isn't specifically focused on doing so. However, it is also engaging in 1-2 hours of daily targeted exercises designed to improve balance and coordination. Now, it probably goes without saying that this will be a long process and "success" is fuzzy. So for the sake of being able to give a reasonable answer, let's say that I am specifically interested in how long until the creature can walk (bipedally!) with only occasional falls. Let's also say I'm specifically interested in *the first time* it tries to master a(ny) new form; as [Willk](/users/31698) [rightly observes](/a/185879/43697), the situation might improve dramatically with practice. (Note: I've tried looking for information on *humans* learning to walk, but while it's trivial to find information on when we *start* walking, it's much harder to find information on milestones once they start. The only source I managed to find was [a youtube video](https://www.youtube.com/watch?v=x7u_dgRmVcI) that gives six months from first steps to running. Is this reasonably accurate? Is this even a reasonable model for the situation of my creature? Would it be plausible for my creature to get to the "usually doesn't fall over" stage quicker; say, in a month? Running can take longer; I just want walking without falling over.) [Answer] **Three to four years for full recovery** The nervous system is complex with a lot of unknowns. Humans, despite the relative long timebin the womb, come out more "unfinished" than most animals. Walking, growing, sexual maturity and more are all taking a very long time. It is difficult to say we're learning them, as they are still growing in the brain and for walking for example the body simply isn't ready to support itself for quite some time. The best way might be looking at people who've been there. Astronauts. They feel wobbly at first, but are able to do quite a few things in a one week, possibly two depending on the training and person. Full recovery can take up to four years. This is because balance and walking have been rewired for use in space. Your shape shifters seem to have mostly just different proportions. This is advantageous, as they'll need to mostly relearn proprioception and the power that goes with it. I would think a month for seemingly normal behaviour is likely. If the dissociation is bigger If the proportions get more complex, like the feet orientate more like wolf paws, it'll take more training than astronauts. The area's of the brain need to completely rewire, as the most used/complex nerves are different from the old. This goes further than just relearning to walk from an astronaut, but still I would say it's in the same ball park. Quite a lot of nerves change tasks during a lifetime and in three to four years of training it's quite likely it happens. [Answer] ### 3 weeks. I had the misfortune of recently having a condition known as "Bells Palsy". Its when nerves on half of your face seize up and you loose control of many of your facial muscles. I looked like a stroke victim. I had a week with a totally paralysed half face (couldn't even shut my left eye to sleep), about 3 days of mad twitching as the nerves started to recover. And then about 3 weeks where the muscles worked individually and would respond if I focused on them, but I couldn't use them right anymore. 3 weeks of slurred speech, biting my lips when eating, spilling liquid while drinking, winking at inappropriate times, lopsided smiling, kissing partner feeling wrong, cutting myself while shaving cause I couldn't keep the skin taught, and crying from one eye cause I'd stared at a computer for hours and forgotten to blink that one. After 3 weeks of being not in control of my functional face, I got it back. It was gradual and I didn't really notice I was improving at the time, I could only see the improvement in hindsight (oh yeah I haven't droolled toothpaste for a few days now. Nice!) Your shapeshifter will go through a similar process. They have the nerve connections, they can make any individual muscle work by focusing on it, and they know the process and sequence they need to do to accomplish a task. I estimate itll take them about 3 weeks of messing up before they can pass for normal again. [Answer] Without knowing the creature's biology it is not possible to give the exact time period needed to start walking. As the OP noted, different species learn movement skills at different paces, with some of them having them at least partially encoded in their genomes. So, in order to make accurate predictions, we need to know much more about the creature in question. However, we can try to establish the timeline in relative terms. It takes about 3 to 6 months for humans to relearn how to walk if they recover from broken legs or other traumas that do not include brain injuries. Brain damage may make full recovery impossible. Full mastery of locomotive skills takes longer, up to 2 years if there was damage to bones and connective tissues. Children need 9 to 18 months to learn how to walk. A lot of this time is spent on growing and training muscles necessary for upright walking. If your creature shifts into a 'ready-to-walk' form with fully formed muscles and nervous system and it resembles humans in its biology **it should take it about ‚Öì of the time that was necessary to learn to walk the very first time**. That is if the new form is not too different from the original one. The bigger the differences between the original and the new form the longer it will take to learn to walk, but it still should be faster than the very first time, because at least some of the pathways associated with muscle coordination should be preserved during the transformation. If transformation always results in a perfectly healthy body with fully formed muscles and the creature is capable of retaining neural pathways related to locomotion the relearning time should decrease for all possible forms, not just the ones the creature already transformed into. If the creature suffers muscle atrophy during the transformation period the ‚Öì of the original time to learn to walk might be the permanent lowest limit for the duration of relearning. [Answer] **Very rapidly. Because of practice.** Your shapeshifters have a limited number of shapes that they use. They are shapes which they have practiced before. Like a martial art or riding a bike, they use learned muscle memory to quickly take on the movements of the new form. These shapeshifters dedicate 3 months every few years to taking on a shape and living in it. This is initially done in protected circumstances and under the tutelage of older shifters, then later in life during time set aside from the world to practice. Often a shifter will have a favored shape that is comfortable (and often one favored by their master or school of thought) and then one or two special purpose shapes that they have not practiced as much. As with martial arts, shapeshifters who are familiar with their discipline can identify other shifters and their styles by their shapes and how they use them. There are occasionally shapeshifters who are "flowers that grew in the dark". They have a self-taught style which is unpredictable to mainstream shifters. Some of these self-taught shifters have spent most of their lives in a nonhuman form, and then it is the human form which is cumbersome and unfamiliar. Some such shifters might not have been human in the first place. [Answer] I'm going to post this as an answer rather than a post-mortem, as it's going to be on the lengthy side. Thank you everyone that answered! I consider all of the answers *useful*, and most were helpful. (Willk's is the exception because it operates on an incorrect assumption, which was totally my fault. As I already noted, however, it's still a correct and useful answer, just not applicable to my very specific situation.) I've *accepted* [this answer](/185883/43697) because it explores a real life scenario with I think is most closely parallel to my fictional situation, and thus clearly meets the "most helpful" criteria for acceptance. Again, it isn't my intent to take away from any of the existing answers, but only to give a more detailed summary of where I ended up in case it's useful to anyone. --- I try to ask questions in a way that is more general, in order to attract answers that are more general, and thus more likely to be useful outside of the extremely specific situation that actually pertains to a particular story. (This is why I still value Willk's answer.) That said, for the very specific case that actually pertains to my story, and that apply to this answer, I can additionally state that: * This is the first time the creature has changed forms. This means it doesn't have the benefit of any prior practice. * The transformation involves alteration of total mass and of mass distribution, but *not* a radical change in style of locomotion. We're talking about something like the difference between an infant and an adult, or a chihuahua and a mastiff, not the difference between a horse and a human (or, even worse, a cat and a sparrow). * The transformation process is able to subvert muscular atrophy from disuse; it isn't having to build muscle mass *on top* of rewiring its reflexes. As far as "learning to walk" and my target level of locomotion, we have on the one hand humans, which would need 2-3 years from birth, while ruminants on the other hand can, if we ignore bipedalism, manage in *hours*. Bipedal locomotion is harder, but also our creature has done it before, so we can probably consider that a wash. We can probably also cut down on the human time because the critter isn't also having to deal with a lack of muscular and skeletal strength. (For the same reason, while we shouldn't ignore Otkin's answer, we can probably similarly cut down on the 3-6 month time a bit; a human in the sort of situation Otkin cites is also dealing with atrophy.) Thus, Ash and Trioxidane are probably on the right track. Accordingly, **3-5 weeks** for "mostly competent" functionality seems plausible. However, it also seems reasonable that it will take years before the creature is completely competent in the new form to the extent that there are no remaining observable effects from the change. ]
[Question] [ Superfluid helium-4 is an extremely slippery substance, which is why I came upon the idea of weaponizing it. One of the planets in my setting is rich in helium, so the weaponization of the element would make sense realistically. The grenade would either leak the superfluid out, or it would detonate and spread it all over the nearby area. Oncoming enemies would have to concentrate on not slipping, which would leave them vulnerable to oncoming fire from the person and his allies who tossed the grenade. It could also be used to stop individuals who are attempting to flee, by tossing it in their path so they'll slip and fall once they step in the puddle. My setting has advanced technology like combat exoskeletons and such, but on-the-ground troops who move on foot are still commonplace, so the act of using a superfluid grenade to impair their movement would be useful. EDIT: My story takes place on Earth for the most-part, so the physics of said grenade would apply to Earth's physics/temperatures. [Answer] # No Given the edit, the helium would vaporize so quickly it wouldn't have time to disperse. It would likely explode like a [container full of liquid nitrogen](https://www.youtube.com/watch?v=F7psvU1H5S4). It wouldn't be a superfluid; it wouldn't be a fluid. It wouldn't even stick around for long. It would definitely *chill* the area, you might give some people frostbite, but a hand-grenade sized container of liquid helium would never spread anywhere significant. --- Edit: to be clear, liquid nitrogen is 75 degrees *warmer* than liquid helium, and you cannot meaningfully pour liquid nitrogen onto the floor without having a *lot* of it. [Answer] No. Even with the obvious problems with Helium-4 noted by a other posters, extensive research has discredited the notion of both sticky and slippery substances as nonlethals. The US Army carried out quite a lot of work in this area -- the most promising was sticky foam but even that did not prove effective. Your best case -- and you might want to use something like graphite rather than Helium-4 - would be that you create an area of slipperiness, assuming you have a flat smooth surface. In normal ground, carpeted surfaces etc the stuff will just be soaked up. This may be useful for preventing rioters from accessing an area, but it not useful in a combat situation, especially when your enemies have real weapons. [Answer] ## No, but not in the way you are thinking. As @jdunlop pointed out, the Helium would immediately boil. However, this in and of itself is *extremely* useful. You see, while jdunlop is right that it will (more or less) instantly boil, *it will still be extremely cold*. "Extremely cold" is an understatement. **With that in mind, I would like to do a frame-challenge and take a step-by-step look at the effects of detonating one of these.** 1. **Sublimation.** When the liquid helium is released from its containment it is going to boil off as *gaseous* helium. 2. **Expansion.** Unlike liquid nitrogen, all of the liquid helium is going to become gas more or less at once. Initially all of this gas is going to be in one spot; however, nature abhors unequal pressures, so the helium is going to explosively expand to equalize the pressure. While it won't be anywhere near as powerful as a hand grenade, it will still do the job of getting helium all over the place. 3. **Temperature Equalization.** While the helium may have boiled off, it is still *extremely* cold. In addition, when a gas expands, the gas does work to overcome the intermolecular forces of attraction (it implies that the gas is spending it's own energy). This results in a decrease in internal energy of the system. Since internal energy is a function of temperature, expansion of gas decreases the temperature of the gas. **The end result is a rather... drastic decrease in temperature. Brrr.** ]
[Question] [ I'm looking to create a lethal disease for a sci-fi book. The plot surrounds a group of rich people taking teenagers off earth to start a new life away from this illness. The pandemic has been going on for a few years already and there's no cure yet. **Some ideas I came up with:** * A [coronavirus](https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2#Infection_and_transmission) mutation, more deadly than existing ones. I wasn't sure how it could be made to lie dormant and what would cause it to reactivate afterwards. * [Rabies](https://www.cdc.gov/rabies/symptoms/index.html). There's a pretty long incubation period, which I liked. Could I make it contagious somehow? Also, I'd need it to be non-curable. * [Klebsiella pneumonia](https://en.wikipedia.org/wiki/Klebsiella_pneumoniae#Transmission)e infection made contagious so that it infects people's lungs and that resists treatment and constantly gets worse? I wasn't sure how this would work. * [Kuru](https://en.wikipedia.org/wiki/Kuru_(disease)) disease. I wasn't sure how to transmit this without cannibalism. Also, the incubation period is 10-50 years, which I'd need to shorten. **Requirements:** * Anyone can be infected by it. The disease can stay dormant inside of them for a few years so no one knows if they already caught the disease. However, at least half the population hasn't been infected yet. Tests exist but are very expensive. * Children aren't endangered by it but are often carriers. They are infected more easily and also infect others more easily. Teenagers can be infected by it but don't develop symptoms until they're in their mid-twenties * All adults (from roughly their mid-twenties) are in danger of developing the symptoms of this disease and dying from it (approx. 90% death rate). * There is no cure and those who do recover are in danger of being infected again in the near future. * I don't care how it was originally started. I'd like it to be all over the world, now, with no cure in sight, only ways to delay the deaths of those who have it. * It needs a name. * Ideally, I'd like to base it off an already existing disease or virus and with create the disease I'm looking for with realistically mutating it. * The most practical way of transmission seemed to be through the air (through droplets) by coughing, sneezing and (to a lesser degree) talking and through contact with contaminated objects and surfaces, then touching eyes, nose, or mouth before washing hands, I'm completely open to other suggestions on this point. The main complications in creating this pandemic are: * The somewhat slow infection rate (I'd like people to still be able to safely assume they don't have it) * Reactivating the disease. How does it reactivate? * Only adults are in danger. Children's immune systems are weakest, so they are most likely to be endangered by such a disease. Any suggestions on how to alter the sicknesses, or for any other diseases/viruses etc. that could create such a pandemic? [Answer] **You have already invented your disease.** If you try to make it a real thing it will just crimp your style. What you have is fine and leaving big unknowns will move your story along. Name it after a place where it showed up and you have got your disease. I would suggest a viral disease or some spin on prion because bacterial are less sneaky. People could have different ideas about that too; it is still up in the air. The only trick is the adults only piece. Leave that up in the air. Maybe the lethal stage is triggered by a second infection, or some other immunologic event, or getting really drunk, or having sex, or getting a shot, or seeing a meteor. People have different ideas about it which will make for good narrative because your characters will have something to talk about. [Answer] One potential idea that you could base your disease off is [chronic wasting disease](https://www.usgs.gov/faqs/what-are-visual-signs-chronic-wasting-disease?qt-news_science_products=0#qt-news_science_products), which can be seen in deer. While no human cases have been reported, it has been shown to infect primates, so it is possible that it could infect humans. Like Kuru disease and mad cow's disease, it is caused by prions, but [as noted by the CDC](https://www.cdc.gov/prions/cwd/index.html) it can be spread through bodily fluids like blood and saliva, as well as contact with contaminated soil. Symptoms occur between 18-24 months after infection, and include continued loss of weight and behavioural changes such as decreased interaction with other animals, and is always fatal. This covers most of your requirements except for it primarily affecting adults. Like Willk pointed out, you could leave as a mystery- there are still a lot of unanswered questions regarding prions so it's likely that in your world there will be a lot that the medical community doesn't know about the disease. [Answer] It could be a variant or mutation of a human papillomavirus (HPV). There are lots of them so a new variant might not be picked up that quickly as it spreads through the population, especially if it seems harmless. HPVs are spread through simple contact and come in a couple of main varieties - one which infects the skin and one which infects mucosal tissue. I would suggest a skin-infecting one that instead of creating a wart, slowly sets up a skin cancer invisibly under the skin which by the time it's detected is already in stage 3. Children's skin is different (thinner or more sensitive or whatever) so when they catch it it's just a really itchy patch that they scratch leaving a tiny wound that the immune system deals with; teenagers' skin is too full of hormones for the virus to be able to survive for long. As to the detection of the virus and making people aware of it and it being taken as a serious threat, well, HPV as it currently exists may constitute up to 25% of female cancers in the developing world. I found a document on human papillomavirus and cervical cancer but it has quite a bit of detail on HPVs generally <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC145302/> ]
[Question] [ **Background:** It's 2020 and the US military needs to invade an alien planet for *freedom purposes*. Unfortunately, the only way to get there is through a Stargate-esqe, non-moveable wormhole located at some semi-secret military base within the continental USA. It's circular, big enough for standard shipping containers to go through, and *maybe* a train that's holding said shipping containers but not much more. **Questions:** * What elements of a modern military invasion would not fit through the described portal and which absence would cause the biggest headache for the military? (eg, no large aircraft, tanks, or ships) * Are there any real-world historical examples of a very large military force invading through a "small opening" logistically speaking? (Through a single tunnel, along a single rail line, etc.) [Answer] If the invasion is planned in advance, the question would be flipped around: generals would ask "how can we get *everything we need* through the portal?". The portals used in the Stargate TV series are [6.7m in diameter](https://en.wikipedia.org/wiki/Stargate_(device)#Making_of_the_props), although I think that includes the ring itself so perhaps 6m of clearance. This is the 'gauge' of the portal, and the good news is that it's both taller and wider than even the largest widespread [loading gauges](https://en.wikipedia.org/wiki/Loading_gauge#North_America) for freight rail in the United States. A huge proportion of the materiel used by a modern military is *already* designed to be transported by rail, and [you would be surprised](https://commons.wikimedia.org/wiki/File:Boeing_737_fuselage_train_hull_3473.jpg) what sort of things you can fit through it. The army logistics corps will spend whatever time and money it takes to ensure that *everything* an army might need will fit through that gauge. Taking wings of planes is a relatively trivial example (for an F-35 you might only need to remove one wing), but there are relatively few single pieces of *army* or *air force* materiel that couldn't be disassembled to fit and reassembled on the other side. Naval materiel is another matter entirely as ships are welded together; establishing a naval force would require the design of 'build-on-site' capital ships (or more realistically quickly establishing a shipyard. I think there's no question that the logistics corps would decide to build a single-track railway through the portal, with enormous marshalling yards on both sides: the portal is a tremendous bottleneck which will have to be utilised *all the time*. But the amount of materiel you can get down a single rail line is pretty impressive. [Answer] This reminds me of an old story (probably apocryphal): The main thrusters on the Space Shuttle were built and shipped to the launch site by rail. That was actually part of the design specification. Well, railroad gauges were originally based on existing roads. Many roads were simply built over the wheel ruts from old horse drawn wagons. The horses were usually hitched side by side. So when you get down to it, the size of the most advanced vehicle on earth had at least one of its design requirements based on a horse's butt. How does this effect you? You need to build 2 marshaling yards on each side of the portal. First things through the portal should be some defensive personnel and some heavy duty weaponry. Start smallish, establish a perimeter, and do your best to camouflage what you are doing. Then bring through some small bulldozers, small earthmoving equipment, and so on to build up the yard. Get some rail laid through the portal, and make sure to build the iris barrier (ala Stargate SG1) so that no matter what happens you can close it off if things go wrong. Once you have the area on the other side established with rail and equipment for you to unload with, you can really go to town. I would guess that two or three rail cars at a time could move an awful lot in a short time. Cargo containers can be used for double duty as well. One intermodal cargo container can carry a bunch of stuff and then double as a barracks or even a part of a substantial wall when emptied. Now, there are a great many aircraft that should be able to get through afterwords. The Fuselage of a 737 can ravel by rail, and the wing and empanage came be sent on another. I have seen repair crews on some smaller aircraft be able to mate the wing to the fuselage in about a day (a lot of wings are just one piece). Jet engines are surprisingly small. Even very large ones are not any larger than a Volkswagen bug. They look bigger but that's just the cowling. That's just an idea of how big you can go. For something like this, though, I would suggest smaller aircraft, like maybe an [AT-6 light attack](https://defense.txtav.com/en/at-6) craft as a place to start. They kinda look old fashioned but they are extremely capable aircraft to get started with and they are fairly small. They can also take off and land on a fairly short, primitive airfield. While you bring through the basics start building things to be as defensible as possible. Concrete barriers can come through and be quickly stacked. Defense is absolutely critical, because if the the enemy closes the portal, you are absolutely done. [Answer] Consider the dimensions of the cargo hold of the [C-5 Galaxy](https://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy#Overview), which is 4.1m high by 5.8m wide. This is of course slightly larger than an [ISO container](https://en.wikipedia.org/wiki/Intermodal_container), but it is smaller than the [Stargate](https://stargate.fandom.com/wiki/Stargate) from the series. If it is possible to put a railway line through the gate which supports high-speed trains, **with a freight yard at the other end**, it should be possible to deploy just about any equipment in a Heavy Brigade Combat Team, in large numbers and with logistics support. Helicopters will fit through, too, possibly with dismantled rotors. Ships and fixed-wing aircraft are a problem. ]
[Question] [ A long time ago [homo floresiensis](https://en.wikipedia.org/wiki/Homo_floresiensis) split off into two main groups: [goblins](https://worldbuilding.stackexchange.com/questions/167656/what-evolutionary-pressures-would-lead-to-goblins) and halflings. Now, halflings still need to eat, and therefore, they need a job to make money and support themselves. Basic characteristics of halflings: * They are 112.7cm (3.7ft) tall and weigh 80 lbs * They have finer motor control * They have slightly improved eyesight * They are proportionately stronger than humans of their size * They are as intelligent a humans With all that said, if halflings were to take part in medieval society rather than live an isolated life, what jobs would they gravitate toward? NOTE: Magic does not exist in my story. [Answer] Mining favored small people since they could fit in the tight spaces easier, egg finder and thatcher would favor light weight individuals. But really the vast majority of people during medieval times were farmers, your job was to feed yourself since food surpluses were small. Which is likely what the majority of halflings would do. Keep in mind halflings are not that much smaller than or average medieval human. Average for a human male was 65.75 inches (167 cm) [Answer] They would probably be exploited by carrying food/weapons for soldiers and be treated like second class citizens. Since they have good eyesight they may also make good scouts for spotting enemies from far away. The lucky ones would probably become accountants. [Answer] How halflings fit in your world depends on how they are treated by other humanoids. Because you are main-streaming them into your culture, one would hope that the relationships are positive and not usury. Humanity has many behavior aspects that manifest in characters. Which aspects do your halflings represent, and which do they bring out in the other humanoids that they interact with? Are they treated as slaves, or are they equal merchants and partners in the business of life? I tend to attribute skills like horology with my halflings. They are the masters of automatons. I would think that they would be in high demand since it doesn't have magic. They can also be boatmen... Disney has a ride full of halflings. It even has a catchy song that plays. [Answer] **They would be sought after as high-end craftsmen and artisans** With a natural advantage in fine motor skills and eyesight, a well-trained artisan could achieve finer and more precise detail than a human of the same skill. Halfling tailors, jewellers, carpenters, metalworkers etc. would be sought after by the rich, to create items with super-fine detailing and luxurious patterns, too fine for clumsy human hands and eyes to craft. This kind of highly skilled work would pay well but require an investment of years of training, so some may have wealthy patrons but many more will be average-skill craftshobbits trying to climb the skill ladder, and still more too poor to get an apprenticeship in the first place. [Answer] Banking. Information brokers. Musicians. Jewelers. Anything that doesn't require one's physical attributes. [Answer] I think there are many things what they could do With their fine motor skills and strength, they could be thieves. They could do both, pick pocketing, opening locks or just beat people for money. Their motor skills also could make them good craftsman. Depending on how xenophobic is your society, they could be important members of craftsman guilds or just wandering tinkerers. their eye side could make them highly valuable to any scouting units, and together with their motor skills and strength could made them very skilled archers. ]
[Question] [ Worldbuilding Stack Exchange. I ask for your aid. In my project, an Bronze-age alien civilization living near the coast has discovered a mollusk that can secrete ooze that later hardens into nacre, the same substance found in pearls. By using molds and the liquid secreted by these mollusks (let's say they are similar to Marine Pearl Oysters), they can create lightweight, strong solid objects and tools. Later, after developing the sufficient tech, this society then uses this material for 3D printing components. My question is this: is this aforementioned liquid feasibly realistic? I know that nacre is composed of both calcium plating and a organic sponge-like layer, and that over time a mollusk can build up a pearl by applying layer after layer of calcium and organics, but can this process be liquidized, and if potentially so, can it be stored and used at will? I am open and appreciative to all answers. [Answer] Can the process be liquidized? I'm not a biologist, but I lean towards *probably not*. At least. Not actual nacre. Is "A mollusk that secretes a liquid that hardens into a solid object" plausible? Sure. There are a lot of things that are liquid and harden, many in the natural world. The issue you're going to run into is the hardening process. If the liquid hardens by itself, it will be difficult to store in a liquid state for later use. However, there's something that comes to mind that can solve this problem. On my work table behind me, I have stuff for making dice. Part of that stuff is resin. It comes in two parts: The liquid resin, and the liquid hardener. When combined, it hardens into a very solid object. So, the liquid that your mollusks secrete? That's the "resin." The hardener? Well, I'm *also* not a chemist but it could be something in its environment that causes it to harden. Remove the mollusks from that environment and they'll just make the liquid, which can be taken and stored. They probably need the hardener to do some natural things, but that can be controlled as well. To use it, all you have to do is mix an appropriate amount of secretion with an appropriate amount of hardener, pour it into a mold, and wait. (Just a note, but this is *not* 3D printing, which is something that would be well beyond what Bronze Age could do even in a "Similar" fashion, but also well beyond anything they would *need* to do either) Is this something that's likely to exist in nature? Probably not. Is something like this going to be a huge plot hole that rips people out of the immersion that the story builds? No. It sounds reasonable and really that's all you need for a story. Pretty much every fantasy, sci-fi, or even historical fiction novels have things that are way beyond this in terms of implausibility and we enjoy reading them all the same. [Answer] Storing the ooze maybe the simple part. Imagine everything begins when a fisherman who collected some mollusks for a meal lets some drops of the ooze fall on something like quicklime. Someone else notices that some marbles of hard material formed in the quicklime because it reacted with the ooze. Eventually they find out they can create the material by mixing ooze with the quicklime when needed. It's the 3D printing that I see a lot more difficult, the tool maybe a dripping sack suspended to a bar moving on some tracks, but doing it manually is not only too coarse, it's a slow process that requires a lot of patience and those carrying out the work must be supported by the rest of the population in a period when people take a lot of time to extract food and resources from the environment. Maybe older slaves who can't do heavy work, but who don't need to eat a lot are turned into craftsmen doing a painstakingly meticulous job. [Answer] A non-answer that doesn't help you in worldbuilding, but is a realistic evaluation of the usefulness of 3D printers in early-human-history. How many 3D printed items does the average modern human own? Probably zero, unless he was given one by a friend or owns a printer. If current 3D printers are not used for creating common items now, similar machines probably won't be useful in the bronze age either. FDM 3D printing is an inefficient process. Compared to casting, cutting, weaving and just about everything else, 3D printing is slow, imprecise, and restricted in material choice. Even if a 3D printer could be built in the bronze age, it would not replace their existing manufacturing methods and probably could not produce items they would be interested in. As a result, even if created, economic pressures would consign the technology to trinket manufacture. --- With hand tools, a skilled carpenter can manufacture quite large items in a day. The Amish did barn raising - creating entire buildings in a single day. Have a go with a 3D printing pen and you'll find out that it's a fairly slow process. Modern hobby-grade 3D printers measure extrusion speeds in mm/s (for a 0.4mm strip of plastic). Printing a 10cm cube takes hours, objects larger than 40cm take days. You want a bowl? A guy with a knife can out-manufacture a 3D printer. --- Calcium carbonate is kind-of terrible as a construction material. How many every-day items are made out of chalk? How many items that a bronze-age-dude would be interested in could be made out of chalk? Knife? nope, knife handle? nope, bowl? nope? Even if the material was passable, single material items are limited. A fully metal spear is heavy and unweildy but a fully wooden one can't won't be sharp for long. Even "wonder materials" like carbon fibre and advanced composites aren't used everywhere for exactly the same reason. There really isn't a one-size-fits-all. --- So given that 3D printers suck, why do we use them in the modern world (and why do I have one sitting under my desk that I use fairly regularly?) 3D printers overcome their slowness in the modern world because they don't require secondary equipment to produce items. Casting (which was invented in the 1600's) can produce items extremely fast, but you have to make a mold - which can be a much more time consuming process. 3D printers allow data to be transmitted digitally. I can design an item here and send it to you there and you can manufacture it. Transfer of information is cheap and fast in the modern world. In the historical world, transfer of information was expensive and the same speed as sending the actual goods. Also, many modern items don't need to be robust. I don't manufacture plows, bicycles or knives (aka useful things) on my 3D printer. Nothing that I manufacture would be of interest to Mr Bronze Age. [Answer] Icing on a cake is definitely a form of 3d printing/additive manufacturing...... You could just do what we now do with icing on a cake, assuming the liquid that hardens upon contact with air/water exists (a lot of things in nature does this-- hot plastics for one, but natural resins and cements are among the materials that are available to bronze-age civilizations. (assuming there is enough tin for the "bronze" part of the bronze age civilization, since the majority of civilizations on earth probably transitioned directly from chalcolithic to iron-using due to the exceptional scaricity of tin in the ancient world.)) For the 3d printing to happen, just put the liquid in a sack, cut a opening on one corner of the sack (or add a nozzle to the end of the sack assuming non-plastic-using setting), and squeeze the liquid onto the substrate like how you ice a cake. (submerged into the hardener is the hardening-factor is a liquid) As the material hardens, add more layers until you get to the desired shape. Certain objects, like containers and simple pipes, could be automated using a variety of machinery that involves cams and cam followers. or other sort of bronze-age mechanical computer equivalent of your choosing. ]
[Question] [ So I've been working on the history of a particular fantasy world and one of its main societies. Specifically how it rebuilt after a civil war that destabilizes government and destroyed larger cities etc. during this a plague breaks out. All in all most people end up dead with a few small groups of survivors scattered around. Whyterith village is what one of these groups ends up forming in to. I'm currently focused around the time (~5 years post apocalypse) when Whyterith is at a population of ~320 people. Whyterith is now producing a surplus of food so the ruling council decide that the village needs to move from an almost entirely farming communist/communal society to one which encourages more rapid growth in order to improve the production of other resources. People will still have to work for the government/society for a certain amount of time each week i.e. helping with planting, harvesting, building, cooking, teaching etc. for the community but will have options outside of the compulsory working time to exchange services and hand-made goods. Things such as child care and school which are all run by the community to allow more adults to work will still continue running. The Council is aware that issues such as inflation may come of introducing currency. I'm curious as to what form of money could be used. I though a rare variety of dry beans that only the Council has access to grow could do as metal is still being redeveloped (they mainly use tools left behind), but I am also curious about how much the Council should provide. I was initially thinking that the council pays all workers 12 beans / week (one for each half working day). Would that be too many for such a relatively small society? Any other problems you can foresee arising? Any feedback or advice would be welcome. [Answer] Do you know where the word salary comes from? It comes from the pay which was given to roman legionnaires, salaries, consisting of salt. Salt is hard to make and until recent time it was highly valuable for this very reason, thus it can be used as convenient value deposit. [Answer] ## Token for a commodity Early Babylonian currency would likely be a good example - I'm not an expert in that area, but as far as I understand, their early currency was tokens issued by the communal temple-granaries that essentially said "you can get 1 [weight-unit] of grain from the granary" and which were usually obtained by handing over grain to the common granary for long-term storage. And that's it - those tokens were used for trade because (a) they could be, they were convenient; (b) they didn't depreciate; and (c) they were 'liquid' because most people either needed them or had use for them, as that stored grain was consumed daily by everyone. This situation seems somewhat similar to what you describe, so reading up more about how that historical situation worked (I'm likely missing some important nuances) could be useful. [Answer] It may interest you that the ancient Egyptians seemed to use loaves of bread and jars of beer as accounting units. We have a number of inscriptions that say things like "give Bob 50 loaves of bread and ten jugs of beer". While low amounts might actually be paid in bread and beer, presumably large amounts were then converted into other commodities or valuables. [Answer] I believe that for a society as small as this, you can introduce a system of community supplies. Let me explain and let's see if this system works. In the village there is a large community hall (or a set of halls at multiple places) maintained by the council, this community hall is like a shopping/free center. All the goods produced within the village, all grains, vegetables, fruits, wood, basically all the basic necessities are stored within these centers. No one is allowed to keep more than 3 days of supply of these things for themselves at home, every single such item must be hoarded at these places. Now, every member of the society is entitled to have a defined quantity of these supplies for them at free of cost, say a bowl of rice or wheat per person per day, either 1 apple or 3 bananas per person per day, you get the idea. Doesn't matter if the person is a farmer, or teacher or the council member, he gets only that much for free. This will give rise to a situation of lazy people, who thinks if they are getting supplies for free, then why work, to avoid this, a work-attendance register is maintained, and people who work as determined by the council will get the supplies. Now the next one is a bit complex and quite unique. People are willing to do some extra work in there free time for the betterment of society, or some simple barter. For instance, If I can make good chairs, I make them and donate them to community hall or maybe for some extra bananas, and someone who requires chair (and strictly those who need them), can take it from the hall, for free (It works on trust basis). Or I can barter my chair for some fine carpets made by you in your free time, or for some exotic berries that you got from your last adventure in the mountains. According to this system (at least theoretically), as no one needs to eat more than they can, inflation may not occur for the basics of life. For the exotics, people can barter for as long as they want. [Answer] Could a centralised bank system work for your society? Then each citisen could trade using a cheque-like system, stating "I owe you 12 credits for this pair of high heeled-shoes you made for me." With these, you could just write out a cheque to whoever you're buying from, they give you the bread then at the end of the day/week/month, the baker brings all of the cheques they received to the central "bank", and however much they are owed is added to their account. That way, the central bank still operates as the main power and can control what ressources are available and how they're distributed, as they would have during the communist era. [Answer] **The [Wörgl](https://en.wikipedia.org/wiki/W%C3%B6rgl#The_W.C3.B6rgl_Experiment)**, a currency tied to labor The basic idea of this currency is that you make a cheap paper note with an official dated stamp, and the currency is tied to labor time. So, if you spend eight hours fixing my fence, I pay you eight Wörgls. You also establish general exchange rates for basic commodities, but since most people work with their hands, the idea that the currency is tied to the time they work is easy to grasp. The reason for the stamps is that the currency loses value quickly: maybe full value for two weeks, half value for the next two weeks, then they're worthless. This is to prevent hoarding, and to make sure that people are continuously making themselves useful. This and other similar local currencies were developed during the Great Depression, so they wanted to make a currency that would facilitate a working economy better than barter, but avoid the hoarding and speculation that led to the depression in the first place. Most of this information is drawn from the book '[Throwing Rocks at the Google Bus](https://www.penguinrandomhouse.com/books/316068/throwing-rocks-at-the-google-bus-by-douglas-rushkoff/)' by Douglas Rushkoff [Answer] Honestly, you do not need a "currency" if your using Mi'ta tax system (a form of tax where one's tax is payed in labor to the government). As you are requiring the tax to pay provide labor to the government in liue of any other currency (you have none of that) or commodity tax (i.e. the government requires so commodity for your production of commodities). Since you're requiring a set time of service to the common good, your tax is a tax on labor (labor is a commodity) and for every 14 billable periods in a week, someone is required to work a percent of billable periods for a community service. Societies like this are rather rare and really, only one significant civilization used this system, the Inca, but they also imposed a Commodity tax on agriculture (and Mi'ta was only for physical labor like construction or military service and then only issued to males and only when required.). In Inca society the Emperor (Sapa Inca) was seen to have a duty to improve the lives of the people by using tribute offered through fuedal exchanges to re-invest in projects to improve communities. Agriculture levies were stored in government storehouses to be used for armies and in time of greater need, while Mi'ta labor was used both to ensure the army had the manpower and develop the infrastructure (including the roads, store houses, and terraced farms that would then be worked by the laborers). While there is evidence that the Incas did have currency (in the form of Ax Monies, ax shaped metal trinkets that seemed to easily denote a value of some kind and may have contained religious significance) and their are some arguments that their complex accounting system might have also been a currency (though no one really knows what the hell the knotted values denote as a standard unit of measure), there is little evidence that they used these measures for internal trade, but rather external trade. Your next problem is your choice of commodity is a perishable good that's easy to counterfeit. For a council that is aware of inflation, this is ridiculously stupid on their part. The reason why counterfeiting currency is such a huge deal is that inflation occurs when there is too much currency is available while there is too little demand for it. Almost every currency is limited by it's issuer's control over the product, and save for feudal Japan, almost all societies used a mineral/metal commodity as opposed to a agriculture commodity because the latter is super-easy to counterfit. It literally grows on trees. Japan got away with it because Japan is actually agriculturally limited due to it's terrain, so rice was basic enough to back coinage as a value. It's also important to understand that a currency is not a commodity, but a physical representation of a difference in value between two distinctly nonidentical things. To use the common phrase, money is literally comparing apples to oranges: Suppose you're a farmer and you have a bushel of apples and you want to trade with your neighbor for a bushel of oranges. Both sides want a fair deal and you insist that you can't give a whole bushel of apples because you need to keep some for rakes so you can grow more apples. But your neighbor doesn't want to give you a bushel of oranges because he needs rakes to make more oranges too. The logical solution is to trade rakes for apples and oranges. Suppose you use 5 rakes to produce a bushel of apples, and your neighbor used 4 rakes for a bushel of of oranges. You can offer to give the farmer 4 rakes for his bushel and you will give him five bushels for a rake. Now you're rakes are currency as they can show a difference between two things that are literally apples and oranges (and if you realize you have to change your apples into rakes before you can change your rakes into oranges, so you make a promise to by bushels of oranges at a later date when you can get your apples turned into rakes, congrats, now you have a futures market). Now this is increadibly simple because you have to ask how do you value rakes to apples? And the metal in the rake and wood in the handle? And the manufacturing speed of rake production? And the rake maker wants a chicken dinner. The problem of the barter system is that comodities exchanges are difficult without some common base item. To solve this, a market may standardize one unit of commodity to another (Like how we said apples equals rakes), but since rakes require metal and wood to make, you need to standardize rakes to metal and wood, and as the product is broken into constituent parts, the product can be removed as you now have a basic commodity exchange developing and the more basic a product comes, the more you can get to a currency commodity: a commodity that is ideally simple in it's base parts, finite or reliably replacable, standardized in size, and universally important to a wide group of consumers. Like I said, Rice was this for Japan in that it could represent useful land. There was a finite supply of rice producing land, you could reliably produce rice, you could put it into standard measuring containers, and everyone needs to eat food (and it's cheap food at that) so it back the Yen, giving it purchasing power. The Yen it's easier to carry 500 yen ($5.00) than it is to carry 500 yen worth of rice. In Europe, where there was more reliable farming land, they used precious metal (Gold, silver, bronze) because metals melt with high heat and could cast into numerous shapes. In fact, most coins weren't just representation of the value of a precious metal but actually contained the exact value of metal. A Spanish Dollar (aka a Piece of Eight or Peso) was worth it's weight in silver because a Dollar was made by molding silver into a circle shape. It was very much literal. And why we still care about the Piece of Eight is that it's the first world currency because The Spanish Empire was involved in so many economies all over the world, including the Americas and Far East Asia. Nations without access to reliable metal sources could accept Pieces of Eight and then melt the coins and mint their own money... this practice still exists in the form of Pegged currencies where a nation will not use a commodity to give value to their currency but will control the ratio of their currency with respect to a very important currency of another nation. Post-World War II Japan switched the Yen from it's backing, cause it's commodity production had been destroyed, to keeping it in a one to one ratio with the USD (and today it's more reliable in a 1:100 to USD... but it's not really pegged). These days this is controlled by buying back their own currency or selling the currency backing it and why we have exchanges. No major currency uses metal backing but is fiat (The USD is the dominate world currency and is commonly pegged to because of this. The USD is backed by "The Full Faith and Credit of the U.S. Government" which has a reliably stable ecconomy that since World War II dominated the world economy. You don't have to deal with the U.S. economy at all... but it's rather hard to do. This is why the U.S. now favors economic sanctions as a punishment before war, as your currency might not be pegged to USD, but other important markets are... and they won't take your monopoly money because the U.S. won't buy it with it's dollars, so they won't buy it with there Dollary-doos... which means you can't trade your goods because you can't get a reliable exchange for them and with enough time, even your own people will abandon you and your policy that caused this problem because they can't feed their families. It takes longer than a war, but the plus side for the bigger market is they don't have to send droves of people into your nation to get killed and are more than happy to watch your government collapse from within. For a TL;DR version, don't use commodities for a currency, but rather think of a currency as a coupon for free commodities from the government supply. One unit of currency should be worth some unit of measure of beans. Inflation occurs when there is more supply of currency but the commodity supply is stagnet, thus the demand for currency weakens while the demand for product does not. The product makers can then charge more for the product because they can get more currency... but everyone else can as well. Typically centrally controled markets tend to respond by mandating product prices be controlled... but really they need to stop issueing currency and release more of it's backing power to get the ratio of available currency to product back into something nice. This is what causes most hyperinflation scenarios and currency collapses, such as Venezuala's ongoing economic troubles, and North Korea's currency nearly getting placed by the confectionery treat of Moon Pies as the population's preffered medium of exchange (and De Facto Black Market Currecy). Yes, a pastry was a more reliable currency than a North Korean Won. ]
[Question] [ **My setting has a lush rainforest planet**, which houses some of the most feared animals in the galaxy. **The abundance of food would make competition tougher and tougher over millions of years of adaptation**. What kind of creatures could survive in such unforgiving conditions? Are there any survival tactics that would become more prominent than others? **How exactly would this shape vegetation, prey and predators?** [![enter image description here](https://i.stack.imgur.com/zB9yF.jpg)](https://i.stack.imgur.com/zB9yF.jpg) **To be more specific what would the plants, prey and predators be like? One example of each at best.** It is very likely that this planet will have cycles of extinction, where a predator has exhausted its prey and will enter hibernation awaiting better conditions. Whenever the population hits its climax predators wear it down to the extreme, thus perpetuating the cycle of violence. If you have any questions comment and editing shall ensue (please don't put this question on hold, just give a warning.) [Answer] # Feared by whom? The bluebottle does not fear the lion. The elephant also doesn't much fear the lion\*. *\*exceptions apply* Here lies your most important factor. Life seeks niches where there isn't too much competition, and where there is a niche there is more life. Each form of life fears its own predators, but to a lion the fly is a minor irritant. If the lion eats all the antelope, it dies. Any predator that's too efficient leaves itself without a food supply. Now there's space for more antelope, if the antelope become too numerous the lions come back to eat them. While all this is going on the prey are also evolving, becoming bigger or smaller, faster or tougher. The ones the lions can't catch have more children. Then the lions have to become bigger or smaller, faster or stronger to deal with the new prey populations. This way all things are held in an unstable equilibrium, nothing can get too big, too strong, too effective. **Predators that humans would fear, hold no such fears for mice.** --- # The deadliest predator on Earth is the dragonfly, with a 95% hunting success rate. Now you have to understand that is something utterly extraordinary, most large land predators manage around 25-30% on a good day. That's also the scale at which you'll find the real savage world you're looking for. Armies of millions marching across the landscape destroying all that falls in their path (army ants). Incredible power to weight ratios, huge flying beasts, acid bites and battles of annihilation for territory. The macro world we see day to day has nothing on the savage battles at ground level. [Answer] Despite their reputation for being dangerous *locations*, if you want an environment that breeds *aggressive* animals, you probably don't want a rainforest. The complex topology of rainforests gives them a lot of hiding spots, favoring a hide-or-ambush predator-prey game, rather than bloody brawling. In fact this is the main reason why they are so dangerous to humans in particular - guns won't protect you from something you can't see. But the animals themselves are not especially violent. This may be one of the reasons why so many jungle animals are toxic - venom is an excellent strategy for ambush predators since it lets them kill a target in one good strike, while being poisonous (and advertising that poison) can protect prey from a sneaky predator that the prey doesn't even know about. Coral reefs are similar, for similar reasons. Deserts also favor ambush over fighting, although in this case it's because of the scarcity of resources - favoring opportunistic predators that can lie in wait while using very little energy, which is why many venomous animals live in deserts. However desert animals aren't particularly aggressive either; nobody wants to waste energy fighting when there is so little energy to go around. If you want hyper-aggressive animals, you want an area with plenty of resources, but not a lot of places to hide. In other words, you want something like the African Savannah. Indeed, almost all of the most aggressive large animals on Earth - both carnivores and herbivores - live on the African Savannah. Few places to hide means that the only option is to run or fight. If you want to make things favor fighters over runners even more, one option is to make running hazardous. Perhaps cracked, uneven ground, regular shallow streams, or some kind of twisty ground vine that grows all over the place (but not very high) will trip up speedy, gazelle-like runners, favoring steadfast prey like water buffalo or hippos. This also opens up a niche for small, venomous ambush predators, just to make things a little more deadly. The most successful large animals in such an environment will likely be built for heavy combat - expect to see armored shells, horns and tusks aplenty. They probably will not be very fast, since the hazardous ground makes running difficult anyway. If you go with the twisty-vine option instead of the grass that has dominated Earth's ecosystem, this gives an extra benefit for herbivores that have sharp tusks, since they can use it to both fight predators and cut up food. [Answer] Before getting stuck in: Ocean life has a longer and richer evolutionary history because life came on land only after it had existed in the oceans for some considerable time. So if you want examples of aggressive and richly evolved animals, and plants for that matter, look at aquatic life. There are several card games on the market where you have a variety of potential cards to play to combat potential strategies by an opponent. Some are reminiscent of rock-paper-scissors. (Or rock-paper-scissors-lizard-Spock if you prefer.) For each potentially lethal strategy there are a variety of potential counters, some of which will be successful, others will be somewhat successful and somewhat failing, and others still that will be total flops. Consider an animal that has to deal with a predator. They could evolve to be very perceptive and very agile and quick. Better eyes, ears, nose, and better legs. That gets you a gazelle or something like that. Or they could form herds and face down predators in groups. That gets you things like buffalo with horns and hooves that, in a group, even the hungriest lion will be concerned with. Or they can learn to hide, possibly by taking to the trees. That might get you monkeys. Or it might get you birds. Or it might get you burrowing animals. Or it might get you camouflage or chameleons. Or, it might get you something like an ankylosaurus, with spiked armor and a big knobby mace-like tail for combat. Or it might get you porcupines or skunks. Or it might get you things like tree frogs that produce poison in their bodies or skin, so that predators that eat them are poisoned. Or you could get animals that eat stuff that makes them bad meals. Or it might get you mimics that look like skunks, or some venomous animal. Or they could tolerate being predated to some extent, and simply be incredibly prolific at producing babies quickly. Such as rabbits. Or they could mix-and-match. Agile and sneaky. Prolific and poisonous. And so on. From the predator's point of view, each potential strategy of its prey must be countered to some extent. The big cats get better senses, at least smell and hearing. Birds of prey often have amazing vision. Some predators become very agile and very fast. Some predators develop the ability to tolerate some poison in their diets. Some predators group up and counter strategies of their prey, such as waiting spaced strategically in a hunting area, so one predator only has to chase the target for a brief time, passing it to the next. If the prey learn to burrow, the predator learns to dig them out. Each of these schemes is followed by some creatures currently or recently living on Earth. The thing is though. Each of these strategies requires time, energy, and resources. They have opportunity costs as well as direct costs. So it is not the usual thing to see a super predator who can do all of these things at top pitch. It's an arms race, but there are strong constraints on things like energy use. If your nearest neighbor can get dinner with 5 cm talons, and you have 8 cm talons, maybe your nearest neighbor will out compete you. If you have armor and poison and huge eyes and ears and so on, maybe your relative with less armor can survive with 10% fewer hours of grazing. And so spends less time vulnerable with his head down in the undergrowth looking for tender shoots. To give a really easy to understand example: A burrowing prey animal will get caught by a predator that can dig. So it must adjust and burrow a little deeper. After which the predator must dig a little deeper. And so on. Eventually the energy for one or the other creature to do the digging will exceed the evolutionary benefit. If it takes a bear more energy to dig out a gopher than the calories he gets from the gopher, it stops making sense to dig out those gophers. If the gopher spends so much energy digging he has no energy left to make baby gophers, it stops making sense. So when this limit is reached, one or the other animal will either die out or learn some new strategy to survive. The bear switches to some other food source, or the gopher learns to hide amid rocks, or some such dodge. So arms races such as this will tend to stop advancing and start radiating. Instead of piling on more and more speed and agility, the gazelle will tend to find some other plan. Such as camouflage. And so on. In other words, things will be hugely varied and complicated with just about every possible strategy being tried at least to some extent. But it is unlikely that any creature will pile up extremes of multiple features. [Answer] It would look empty, for starters. To grow from a child to a fully grown adult and then get more children you need more food than you weigh. Eating meat is the most energy rich method but also requires a lot of energy to hunt, and if everyone is a violent meat eater you quickly run out of that meat so you need a massive amount of plant eaters to sustain a small amount of predators and still have enough plant eaters left to keep the cycle going. Plant eaters that go stealthy or become fast or fly to avoid predators would have an easier time getting children and eat the food of violent plant eaters, but lets imagine that for some mystical reason the plant eaters also became violent to protect themselves. This would mean that there is a large chance the predator dies instead of the plant eater or that they both die, this leads the way to scavangers to become more prominent. It would also mean the predators would need to become smarter and hunt in groups to avoid death by plant eaters or have to gain intelligence and tactics to strike at another violent creature when they are vulnerable. But all in all the increase in energy to do violence across the board would mean more food consumed by the average creature and therefore less food available for everyone and with that less creatures about. The violent cycle should normally be broken due to the higher efficiency of less to non-violent approaches to surviving on the planet. Why fight if you can hide or run to stay out of trouble? As for plants, they are plants and have less energy for movement. Their violence would be limited and you would get creatures that have protection against it. Like poison leaves or darts fired by plant pressure wouldnt go through a thick fur hide for example. [Answer] The animals would be shaped by the presence of the forest. On the ground it would be very dim even in daylight and there would be lots of canopy for climbing in so I would expect monkey like creatures and snake like creatures to make use of that canopy. I do not think the circumstances you propose are that different to what happened on Earth historically. Your world-wide rain forests would be on a larger scale but not intrinsically any different from say the Amazon. Natural selection and survival of the fittest are harsh masters in all cases. ]
[Question] [ I have only encountered the "Sonic Boom" a couple of times in my life, once when I was lucky enough to watch Concorde fly over my town in the late 70's. In a story I'm writing someone claims to have encountered/observed something that travelled Faster than Light. And obviously the question is "How would they know how fast it was going?" I would be interested to know if there is any thought or theory as to whether a vehicle or object moving faster than the speed of LIGHT would have a similar light based effect. I assume it would create a hell of a sonic boom, but would there be a massive flash, or a mirage type bending of light as well? Are there any other theoretical tell tale signs that something had travelled faster than light as opposed to just "Really really fast"? For example purposes, let's assume the object in question would be roughly the same size as a passenger plane. [Answer] Yep, its called [Cherenkov radiation](https://en.wikipedia.org/wiki/Cherenkov_radiation), light emitted by particles moving faster than light in their current medium. In real life this is impossible in a vacuum, but in some materials (such as water) high energy radiation can travel faster than the local speed of light. It looks a bit like this: [![Cherenkov radiation](https://i.stack.imgur.com/vjNNm.jpg)](https://i.stack.imgur.com/vjNNm.jpg) That's an active reactor core in a deep water tank. > > Are there any other theoretical tell tale signs that something had travelled faster than light as opposed to just "Really really fast"? > > > Well, its hard to be really certain about this, because superluminal travel is problematic for many, many reasons discussed elsewhere, but here are a few thoughts. With a ship flying *towards* to, as it has travelled faster than its own light, you'll be able to see the light it had emitted catching up with it. The light emitted most recently will arrive first, then light emitted earlier. This means that you'll see an "echo" of the ship *shooting backwards* away from you into the far distance. There's a non-FTL effect a little like this called a [light echo](https://en.wikipedia.org/wiki/Light_echo). The "echo" will propagate pretty quickly, so I'm not sure whether you'd be able to see the effect unless the ship was travelling over a very long distance (eg. lightseconds or more). A ship flying *away* from you won't show this effect, as the further away it gets the longer the light will take to reach you. Things will probably get even weirder if you observe a flyby rather than an arrival. The first light you'll see will be from where the ship was at its closest point towards you. Then \_ *think* you'll see the FTL-light echo receding from you, and the light of its flight away from you *at the same time*. If you couldn't tell front from back, it might look as if two ships appeared together and shot off in opposite directions. Now, there are of course issues of blue- and red-shifting, but it isn't at all obvious to me that you'd see those effects on a superluminal object (inasmuch as it is possible to even have a superluminal object you could see) but as things have already tottered out over the cliff of plausibility, you could probably handwave that as you wished. [Answer] There's no way to extrapolate from the physics we know to answer your question. There are actually two speeds to keep track of: the speed of light (the speed of electromagnetic radiation) and the speed of causality (the fastest speed cause and effect can propagate at.) In a vacuum, electromagnetic radiation (being carried by massless particles) travels at the highest possible speed, that of causality. (Relativity explains why nothing ever travels faster than causality, (FTC).) In matter, interactions between the EM field (or, equivalently, the photons of the electromagnetic radiation) slows the effective speed of EM radiation to less than the speed of causality. (The effective speed is dependent on the details of the material medium and the wavelength of the EMR -- in water, for example, visible light travels significantly more slowly than x-rays.) The speed of causality is unaffected. Cherenkov radiation is caused by a material particle moving FTL (though more slowly than causality) through a material medium. So Cherenkov radiation is not the answer, because the interactions between the FTL (but not FTC) particle and the material medium are themselves limited by the speed of causality. The postulated FTC particle *could* not interact in the same way. So whatever happens, Cherenkov radiation is not it. What does happen? As I started this answer: There's no way to extrapolate from the physics we know. The theories of Special and General Relativity describe the fundamental nature of space and time and causality and the introduction of an FTC particle simply generates contradictions with even cause and effect breaking down. This is a *very strong sign* that one of two things are true: (1) FTC particles are impossible or (2) Relativity is not a correct theory of nature. In case #1, there's nothing to predict. In case #2, we know that the only theories we have that describe the world around us are wrong, so we can't expect them to make useful predictions of an FTC particle's behavior. [Answer] One effect could be the illusion that the craft is moving backward, as the light from the vehicle being close to you reaches you before the light of the vehicle being further away. This would only happen if the vehicle was moving toward you. *Edit: thinking about it a little more, what you'd likely see is a streak flashing out from the point of closest approach in both directions, forward and back...* Another possibility would be a radiation burst followed by a radio burst, as the light is red shifted/blue shifted way out of the visible spectrum and into gamma rays as it is moving toward you, and radio waves as it is moving away from you. [Answer] The usual answer is [Cherenkov radiation](https://en.wikipedia.org/wiki/Cherenkov_radiation). This emitted when particles are travelling faster than the velocity of light in the medium they are passing through. This is often seen in nuclear reactors where the particulate radiation from fuel rods exceeds lightspeed of the medium, usually heavy-water, in which they are immersed. Back when tachyons were the favour of the month in theoretical physics, there was a research paper that suggested that faster-than-light objects might generate a gravitational shock-wave accompanying their motion. This suggest the instruments necessary to detect a tachyonic gravitational shock-wave, would be a form of gravitational wave detector. ]
[Question] [ This is a follow up question to one I asked earlier:[How can religions be structured in ways that allow inter-faith councils to work?](https://worldbuilding.stackexchange.com/questions/151781/how-can-religions-be-structured-in-ways-that-allow-inter-faith-councils-to-work/151861#151861) So, these gods are basically artificial intelligences that are constantly running in the background of the world. It is similiar to how software is always operating on an Imac, working to keep everything running without our notice. These gods can be commmunicated with by taking certain steps, which human beings know as "magic rituals". In actuality, humans are simply communicating with the nano-machines in the air, which the gods are made up of. These nanites are known to humans as "mana", the energy of life. While they are too small to be seen, these nanites are everywhere and serve as the eyes and ears of the gods, allowing them to interact with the world. When humans perform these specific rituals, the nanites come together to form a "daemon" of that god. The type of daemon formed would depend on the ritual being conducted, as there are multiple daemons tied to a god. These rituals are all different, dependent on certain materials, steps that must be taken, and other requirements. If the ritual is successfully completed, the creature would appear and fulfill the purpose it was made for by that god, such as impart knowledge to humans, help with a certain task, etc. However, there are certain areas of the world that, due to certain events in the past, do not play by the rules of nature. These areas are known as hostile zones, for they are covered in "chaotic" mana. These nanites do not follow the rules of the rituals and form at random intervals into hostile entities called demons. These creatures are the basis for the mythical monsters seen in folklore (wendigo, lahmia, etc). They operate without rhyme or reason and cause destruction to anyone and everything around them, including each other. Some of these entities made are corrupted, bastardized versions of established daemons, while others are completely different and made up of a hodgepodge of different parts. These are like the dark forests in traditional fantasy stories, where evil creatures or witches roam and bad things happen. There are no physical boundaries separating these "chaos infested" lands from other places, but humans know not to go there. This is the problem. These demons don't play by the normal rules of creation. Yet they are bound to those specific areas and don't spread out from that domain. How would this be the case? [Answer] Nanites should have sort of immune system: they are destroing xenonanites. The destruction is mutal. It means that diffirent "races" of nanites would form clusters with constant everlasting immune "battle" at the border (wich generates very toxic grey powder wich clearly desegnates the border of "evil lands"). The size and a form of this cluster depends on balance between production-destruction of nanites of both types, and this balance can be extreamly stable or fluctuating (like predator-prey balance in nature) [Answer] The key word in "Dark Forest" is "Dark". Each nanite is self regulating with a fundamental AI and strong community/pack instincts. Normally, it receives its instructions from the AI via a radio circuit which is powered by a small solar battery. Any nanite which is exposed to sunlight charges up the battery and contacts the AI for instructions. When a nanite goes without sunlight for more than a couple of days, that battery runs dry and it loses direct contact with the AI. In this situation, its pack instincts take over and it starts obeying directives from any nearby nanites. It is in the unexpected interplay of separate nanites' last orders that the apparently chaotic action of demon creation occurs. During such chaotic activities, the rest of the nanite's systems continue to operate because they are chemically powered like real life forms. The radio, however, being an electromagnetic device, needs electricity which can only be acquired from sunlight or city-based broadcast power stations. The Dark Forests are all too dark for solar and too far from the cities for broadcast power, so any nanites which gather there are on their own. [Answer] The World is covered in a grid (like latitude longitude not a physical grid) of AI controlling the nanites that makes them able to manifest themselves as gods during said rituals. Some part of the world those datacenters or computers where the IA brain is located or where they are controlled from are damaged (during ancient times or due to temporal decay etc) so that a square of the grid is not connected anymore thus the nanites inside the grid not interconnected anymore are gone rogue (depending on the needs bugs can make them hostile to everything or specific locations or times of the day etc). The software that attributed them the location as to where to manifest or roam is not updating their location of operation so they are stuck in their square of the grid and can't cross it even though no physical barrier exist [Answer] If your world is a giant computer that accepts user input, then it is by definition vulnerable to computer viruses that can be created by your magic rituals. In modern computing, you can't defend against every possible virus; so, you set up an antivirus program with authority over all other programs that follows heuristic rules to identify suspected viruses and contain them for study. If you prevent heuristic patterns too aggressively, you tend to cause irreparable damage to your system by attacking false positives. Instead, you quarantine the suspected malware until an admin can come along and decide if it is good or bad. In short, the virus only expands to fill the dark forest because that is the limits of the permissions it has when the quarantine is set. **To answer your question:** They are contained by Norton, the God of Cyber Security Norton is a wise and powerful god created by the Titans long ago to keep an eye on the other gods and make sure they are not tricked into unleashing horrible evils into the world. The dark forests are his creations. In times past, he would create them for the Titans so that they could study the demons before destroying them. That way, they could find better ways of preventing them. As such, the dark forests are not random mistakes as some may believe. Instead they are the result of ancient wizards (hackers) who tried to break the laws of magic. Instead of their evil creations spreading across the world, Norton who listens to all rituals, saw that these were possible viruses and contained them. While Norton has the power to destroy demons, he does not do so unless ordered to. Instead, he simply awaits the day a Titan will give him the command to finish the job. From the demon's perspective, it may not even know that it is contained. Like a virus stuck in a virtual machine, it believes its forest is the whole world. That which is beyond can neither be seen nor accessed. This also raises the option of adding exorcists to your world. Priests of Norton with knowledge of the ancient rituals that were responsible for triaging quarantined viruses. Basically, they can go to such a forest and perform the delete quarantined virus ritual to have Norton destroy the demon... ofcourse, Priests of Norton could also misuse their power to release a quarantined demon; so, the number of people trusted with this arcane lore would be very small. If the wrong demon were released, saying the results would be catastrophic may be an understatement. Another interesting area to explore is the daemons that were false positives. Perhaps things like unicorns, pixies, and platypuses were good creations, but are heuristically so similar to demons that they were trapped too; so, sometimes Priests of Norton will come along to free them. And in a true hacker fashion, dark mages may occasionally disguise a demon as a goodly being in the hopes that someone will free it. [Answer] # Semi-Autonomous overrides of behaviour when communication has been severed. My simplest explanation would be how the nanites perform when they don't have communication with their central orchestration entity, possibly due to signal interference or naturally occurring EM emission. If these nanites work by being constantly in communication with the host entities, when this communication drops by a temporary loss-of-signal, or a slight variation in signal strength, the node would need a contingency to be able to "work offline" for the period, rather than going completely haywire. They could even have different levels of behaviour based on different lengths of time away from communication, such as so-called "master-slave" configurations. These occur in tech when you have simultaneously executing systems that need to orchestrate for a purpose - a local cluster of nodes "elects" a master node, which tells the other nodes what to do. One such eventuality could have occured, where the elected nanite orchestrates the slave nanites into a hostile entity to prevent their capture for study or reverse-engineering by a hostile party. [Answer] # Signal emitters/scramblers Your world could contain a vast space of chaos-lands, much like several RPG videogames where any attempt to go "outside town"—outside an "island of safety", rather—results in attacks from random monsters. Or it could contain a vast space of safe-lands with "islands of chaos." Either one works with this explanation. The order among nanites is created by a constant pressure towards long-range structure in conformity with the gods, which is an electromagnetic transmission which we can call simply, the Signal. If you have islands of safety, then the world consists of nanites in Discord and the Signal is transmitted by a couple of exceptional artifacts which exist at the core of each of the islands of safety. If you have islands of chaos, then the Signal is being broadcast worldwide but a counter-Signal, a Discord, which cancels its effect out, is being spread out from those exceptional artifacts instead. The same basic principles hold either way. The artifacts protect the islands against direct incursion from the outside world. The entities inside the island want to reproduce the artifacts and spread their influence larger; the entities outside the island are not necessarily directly concerned by the islands themselves but do occasionally organize larger attacks on the islands to try to "beat them down" so that they do not take over too much territory. You want to try to set up some mechanism by which the islands become **stronger** as they get smaller or fewer in number, so that they naturally balance at some equilibrium point where the islands don't get completely eliminated but also don't grow to encompass the entire world. So for example maybe the island-of-chaos artifacts produce a sort of “antimagic zone” plus a larger zone of Discord; or perhaps in the reverse case monsters simply can't exist within a mile of the Signal sources, but civilization of course extends further beyond that round mile and the fainter amounts of Signal discourage Disorder's monsters from entering that city where they will weaken. ]
[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/149788/edit) This government regularly saves the world from megalomaniacal super villains bent on world domination. They accomplish this through a specific branch of agents that specialize in taking on this level of criminal. These agents use numbers to identify themselves and pseudonyms to keep there true identities secret. These agents have been operating since the 1960s, and have an unrestrained licence to kill in the name of defending the government. The individual who adopts the number and pseudonym changes when their predecessor retires or is killed on mission. They are required to perform their duties while adopting the same habits expected of their position set in place by the first of their number: 1. They are mandated to use a specific kind of gun, the Walter PPK 2. When on mission in an establishment serving alcohol, they can only order a dry martini, stirred not shaken. 3. They must be womanizers who sleep with any woman they come across and leave behind kids that they take no responsibility for. 4. When meeting someone for the first time, they absolutely must introduce themselves with their last name, then their full name. Every agent that has adopted this role has fulfilled it with the upmost satisfaction. However, after 50 years of this, problems are bound to develop. Using the same false identity and code number will likely get that person recognized, undermining the purpose of being a secret agent. Although the individual has changed, they would still tip off the person who they are hunting, leafing to their capture and death, or at the very least, force that supervillian to go further underground. The agent needs to perform his duties while on mission, and retain the very same habits and style of his predeccessors. How can I make this happen? [Answer] I think the classic reasoning behind the situation you describe is that the person is *supposed* to be conspicuous. Their job is a "secret" only in the sense of "plausible deniability". There are a few reasons you might want to have an obvious, known, secret agent with a track record of bringing down massively powerful antagonists to the state: * They serve as discouragement to people who would like to antagonize the state, and feel like they *might* be powerful enough to get away with it. * They serve as reassurance to powerful (wealthy) people who are unsure whether they should invest in the state's status quo or not. * They serve as a distraction from actual secret agents, who can't afford to get shot at while exfiltrating the evil warlord's financial records. [Answer] I know the stereotype here is James Bond, but as it happens, there's a second very notable secret agent who fought actual megalomaniacs which was three different people using the same code name. I am referring to Tanya of the Red Alert franchise, who is the American commando in all three games, and a different person each time. The popular fan theory is that the position is just called 'Tanya' as a code name for the anti-Russian commando. The answer to your question is that your concept works very well for a spy which isn't actually a spy. Someone like Tanya, for instance, or the type of spy that does no undercover work and just leaps from exploding buildings, has shootouts with evil-accented villains, and has slept with every woman/man within a thirty mile radius. A romanticized spy, like James Bond, who is not really a spy, and is more of a commando, or the main cast from Mission Impossible. (The movies, not the old show.) On the other hand, these rules will kill the spy well before your fifty-year limit. Probably on the third mission. If someone undercover is known for ordering a dry martini, shaken not stirred, that's all it takes for him to blow his cover. The best way to be undercover is to have *no* discernible habits. Spies train to *break* their habits, because those get you killed. The best spy, as they say, is one you've never heard of. [Answer] I imagine that the agents would retain two or more homophone identities, that is there is James Blonde, the secret agent, and there is James Blonde, the IT professional with a passion for Cosplay and dystopian graphic novels. The geeky IT professional is socially transparent, and his or her entire life is viewable on social media sites as a series of argumentative posts that Prince Namor is not a rip off of Aquaman, but an original and nuanced character in the Marvel Universe. This is the day to day identity for the agent, hiding in plain sight. A change in wardrobe, gait, and hairpieces -- namely male pattern baldness wigs -- and nearly anyone with the approximate build can take their place. Admittedly it is challenging when the rare numbered agent survives to die of old age, in which case a son or grandchild takes on the role. On missions, the suave and debonair persona emerges and goes about seducing anything with tits, even if the true person is trans or gay. It doesn't matter, they are committed to the role as much as they are to king and country -- or queen and country as the time period may require. I've heard tell that numbered agents train at the Shakespeare's Globe Theater for years to learn the craft of acting before they get their first lesson in Judo or Savate. Anyway, when duty calls the mild manner secret identity gets the flu or a disturbance of the bowels caused by eating gas station Sushi, which they share in minute detail with their social circle, but in fact they dosh the Khaki's and don the Pierre Jordan suits with cashmere underwear and baby seal fur socks. This work because of 90% of the people that witness anything spectacular end of dying in the crossfire or sleeping with the agent. In the case of the latter, the numbered agents are experts in somatic reprogramming and subtly manipulate the subject's memory to make the numbered agent even more mysterious, good looking, and taller. Then the agent is free to return to their mild manner identity. [Answer] **Many other people use the same alias.** If I check into a hotel under "John Doe" the woman at the counter might smile and say "I've heard of you, Mr Doe." To which I reply "I get that a lot." With a sly smile, of course, because I am that Mr Doe. The alias of these agents is more like "John Doe" than "Mark Wyzowski". It is an alias which a lot of people might use and so not useful for identifying anyone in particular. It is understood to be an alias by anyone who comes in contact with it. There are any number of reasons a person might wish to use a pseudonym. If nefarious types become aware that "John Doe" has checked into a hotel in their city, it might be the agent, or it might be a Lebanese jewel merchant, or some dude with many debts, or it might be Mr Wyzowski and his mistress. You can't check every single time. The code number is a different matter. That is for internal use only. ]
[Question] [ I have characters with ice powers. I was planning that they could freeze an injury and prevent it from progressing. An arrow is shot at their heart, but I could possibly change the location to make the situation more probable. [Answer] Unless you use a healthy dose of story telling Magic, No. The heart is constantly moving and pumping blood through out your body. Freezing something that needs to move isn't going to work. It also doesn't help that your blood will likely freeze, causing the water in it to expand into ice crystals which will tear up your blood vessels as your heart tries to pump it through your system. You would also be dropping your core body temperature since you are literally freezing your heart. So realistically. No. But with good story telling, you never know. Maybe the arrow just missed the heart, you could certainly use some ice to freeze it in place to make sure it doesn't shift around and cause more harm. Or maybe you created a tiny ice shield in front of your heart that stopped the arrow from piercing it (which you then quickly removed). [Answer] **High heat can cauterize (think "weld") a wound. Ice can only immobilize — at a price** Any temperature outside the range of what the body wants to experience is damaging. To much heat and you burn. Too much cold... well, we call that "burning," too (freezer burn). But where heat will solidify the fluids around a wound (cauterization) such that the body can return to room temperature and not bleed, cold cannot. And it's that solidification process that's the problem. sure, enough heat (or heat over a long enough period of time) will solidify the flesh, too (known as "cooking"). But cold doesn't have the benefit of staying solid at room temperature, which means it must be kept cold, and all the surrounding flesh with it. And it doesn't help that the body generates its own heat, which is constantly in conflict with the ice, so you must constantly keep reinforcing the ice. So, staunching a wound is kinda out of the question (unless you can be *really, really, really* precise with the application of the ice!). But, what could you do? Frankly, anything a split can do. For example, if you're dealing with a broken leg, an ice cast could be formed around the leg (especially if clothing is left in place) to immobilize the leg. You can also assist with medical treatment. For example, it's common to lower body temperature during cardiac surgery. Ice would be a dramatic but useful tool for that purpose (if carefully controlled, of course). But, to help with, say, a knife wound? Not really an option. Think about how it would feel if the hot knife used in an emergency to cauterize a wound was left on the body and *always had the same, heated temperature.* The damage and pain would be amazing. Ice would have the same problem. [Answer] If you want to use ice powers to stop a wound, freezing the wound isn't an option. But *cryopreservation* is. Freezing wounds isn't really a good method for healing them, but it is a good method to stop cellular decay. If someone suffers a fatal wound, immediately dropping their body tempature to around 35 degrees Farenheit will be helpful. Sure, it kills the man, but it delay things like the four-minute mark to permanent brain damage. Lower than that is freezing. And once you freeze cells, that's a lot of completely irreversible damage. That said, the wounded person is still dead once you drop the core tempature that low, because the human body wasn't meant to come back from tempatures that low. On the flip side, if there's healing magic (or, as per Clarke's Third Law, technology) that can regenerate limbs, or something of that nature, than a person deep on ice like that can be revived, because the brain isn't dead. [Answer] **Maybe, depending on how your magic system works.** If you're literally using ice, probably not. However, if you're using more metaphorical associations of ice to conjure up some form of slowness or stasis magic, then it might be possible to do so. You might also be able to use ice's associations with slipperiness to make the arrow glance off. [Answer] Ice, no. Not if we're talking about big lumps of frozen tissue. But if your character has very fine control over their power, then we can work with this. Perhaps they can rapidly chill the tissue, to a point just below zero? If you actually get ice crystals forming, you're going to have widespread tissue damage (as other commenters have noted). Can the character direct this chilling power very specifically? Can it be directed to individual vessels (that would constrict with the cold)? Thus a wound to a major organ or limb could be effectively shut off (effectively acting as an internal tourniquet). If you go with this route, I'd recommend you go with the liver. Very highly vascular, will bleed a lot and cause a life-threatening injury, but can survive cold and has great regenerative capacity. ]
[Question] [ I'm writing a story about a race that has space travel capabilities without rocket technology, instead is using a portal to space and was wondering whether it's possible for them to put something in orbit, and more precisely: Is it possible to launch an object into portal A inside a vacuum tube so that when it exits the portal at the point B it would enter earth orbit? Assumptions: 1. Side A of a portal is attached to Earths surface and is perpendicular to the surface. 2. Side B of a portal opens in space, on a line from the center of the earth, through side A to a point outside of the atmosphere with a (possibly) arbitrary distance. It is aligned perpendicular to the Center-A-B line. 3. The velocity vector of a thing entering the portal and exiting the portal is constant. 4. The side B of a portal doesn't move. It's fixed in space for the amount of time it takes for the line from earth center through side A to move more than r^2 where r is the radius of the portal. (Clarification: imagine a long pole from the earth to the B side. At portal opening, pole is at -r^2 from the center of the portal and lasts until the pole hits +r^2 from the center of the portal. So if the portal is 2m in radius, the "breakpoints" are at -4m and +4m, so at 1000km the portal would last 0.1097s) I can't get my head around the math required to compute such an outcome, and was wondering whether you can use Earths gravity to faciliate such a launch. They use manuevering thrusters and they do have fireworks, but their rocket technology is nowhere near as sophisticated as ours. They rely on ballistics to get the job done. [![enter image description here](https://i.stack.imgur.com/sj2fY.png)](https://i.stack.imgur.com/sj2fY.png) @JBH: Portal doesn't transfer gravitational forces, only matter and EM radiation (thanks for the heads up on the issue) And yes, the idea is to make the portal further than the desired orbit and use the "falling to earth" with small manuevering thrusters to "get up to speed". I plan on using the vacuum tunnel to accelerate the rocket on the ground to reduce the fuel requirements even further, because something like even 100m/s is a whole lot of energy I don't need to bring onboard. As per restrictions, portals are perpendicular to the surface of the sphere at the point of intersection with the ground. Thus no "falling rocketry". @MarkOlson: The potential energy is technobabbly created from unobtainium radiation. Not something I care about, because there's a lot of ways it could work (energy used to send the matter could include that delta in potential energy) amd have not settled on the way it's done. Thanks for the heads up on this issue. [Answer] AtmospheriPrisonEscape's answer in [this thread](https://worldbuilding.stackexchange.com/questions/137790/life-on-giant-planet-can-centrifugal-force-reduce-gravity) gives us the equations needed to calculate velocity at any particular orbital height: > > Any small mass $m$ orbiting a large mass $M$ has its centrifugal force > balancing > gravitational acceleration exactly, so that > > > $$g = \frac{v^2}{r} $$ and the gravitational acceleration $g$ is the > result of the planetary mass $M$, gravitational constant $G$ and > distance $r$ via > > > $$g = \frac{G M}{r^2}$$ > > > so that any velocity that fulfills the force equality is $v^2=\frac{GM}{r}$, also called Keplerian or orbital velocity. > > > *edited for MathJax formatting error* # Edit upon clearer understanding of the question: What you'd need to do is calculate the orbital velocity at the height of the portal, subtract 460m/s (the surface velocity of rotation) and accelerate your payload till it reaches that speed before entering the portal (ie for geostationary velocity: 3.08km/s - 460M/s = 2.62 km/s). Now 2.62 km/s is freaky fast to do inside the atmosphere - our current [airspeed record](https://en.wikipedia.org/wiki/Flight_airspeed_record) (in a jet) is 0.97km/s in a [Lockheed SR-71 Blackbird](https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird), Ok, the space shuttle's effected re-entry much faster than this but where the atmosphere is thin. If you're looking to accelerate the payload into a stable orbit (other than at an orbital radius greater than the moon's) You're going to need to calculate the disparity between your achieved orbital velocity at whatever velocity the payload enters the portal and the needed velocity and using F=mA in newtons, gramms and metres per second - to calculate the thrust your "firework" will need to make-up the difference. - This whilst calculating for the firework itself shedding mass as it burns. *The disparity in gravitational potential energy could perhaps be explained in term of the energy the wormhole requires to run (which would be **loads**) - but beware, if an object enters the orbital wormhole and exits the Earthside one you'd need to dissipate the energy somehow.* [Answer] **Most people who use portals ignore gravity, etc.** If you have a [Saturn V rocket](https://en.wikipedia.org/wiki/Saturn_V) standing on its pad and open a portal right above it... 1. You have a *massive problem* with atmospheric loss through the portal. As in catastrophic, it-makes-hurricanes-look-like-spring-showers loss. Sea-level pressure at Cape Canaveral vs. *zero pressure in space, literally zero.* Heck, the wind through the ~~vortex~~portal might suck the rocket through without even igniting the engines. Even if the rocket survived the transition (what happens when something strikes the edge of an infinitely-thin portal entrance? It probably cuts like a hot knife through butter...), the sudden change in surface pressure on the skin of the rocket would likely burst it like an over pressurized beer can. 2. Your portal doesn't magically suspend the effects of gravity. In fact, opening the other end of the portal so close to Earth might have serious repercussions for Earth because suddenly there's this portal at orbital height *that has the same gravity as the surface of the Earth tangential to the surface of Earth.* Anything from ripping atmosphere away from the planet to ripping chunks of rock off the surface could happen. But more to the point: that Saturn V must achieve 11 kps just as it would normally for the same distance — it's just doing most of that flying in "space." The gravity well is identical, the portal just shifts the location of the well. OK, let's ignore the effects of gravity and ignore the effects of atmospheric pressure. 3. The rocket falls back to Earth in a glorious fireball because it's not traveling anywhere near fast enough to maintain orbit. Now, to be fair, you could assume the rocket burns its engines long enough to come up to speed and adjust the angle of departure for the exit of the portal because the rocket is going to start falling back to Earth and that must be accommodated. Set up the angles and the length of the engine burn properly and you can survive this. *BUT! what if you take everything I just said and designed both your rocket and your story to deal with the issues. Perhaps nobody's done that before, and it would be mega-cool. The effects of gravity may mandate a minimum distance from Earth for the portal exit, meaning rockets must swim **back** to Earth's orbit (NOTE: You either understand this or have an innate concept of it because your diagram shows this)... Maybe you take advantage of the pressure change to lower fuel, making your rocket lighter... etc!* **One more thing...** If you have the ability to open portals, why wouldn't you open the portal on the ground, below the rocket? This would let Earth's gravity pull it through. The gravity within the circumference of the portal may be zero, but the gravity around the circumference isn't. The gravity on the *other side* of the portal would be wonky... so much so that I'm getting a headache trying to work out exactly what it would be... but it would likely save you a ton of fuel not having to push up to the portal. Suddenly it makes sense to "launch" rockets upside down. [Answer] ## Yes, but there is still no free lunch Assuming your portal is a **relativity-compliant wormhole**, with one end sitting on the ground and another in orbit, it would absolutely work. You cross the ground portal at walking pace, and you emerge in orbit, drifting away from the space portal at walking pace. The portal itself is pushed in the other direction, but as it is probably much, much more massive than you, it shouldn't make much of a difference. Still, keep that in mind for orbital corrections. However, things are never that simple. **You have to balance how much mass goes both ways**. Basically, each portal gains mass when an object enters, and loose mass when an object exits. If too much mass is transferred in one direction, one of the portals will loose all its mass and the wormhole will crash. Both ends of the wormhole are created at the same place, so you have to launch the space end the hard way. This means that unless you have already lots of stuff up there (say, a conveniently redirected asteroid), **you will still have to launch the same mass in orbit**, but in one go. You could use another wormhole exit already up there, but it won't help you per se, as the older portal will still loose mass equivalent to the new portal. **Also, time is passing differently for both ends**, as the sky one is in orbit going faster but higher in the gravity well. As we know from atomic clocks on satellites vs on the ground, there is some drift. This means that your wormhole becomes a time machine: if there has been one second in time difference between both, **crossing it will take you one second in the future or in the past**. **As long as both ends are far enough, that's not a problem**: even light cannot make it back fast enough to arrive before it crossed the portal. In fact, if you want to use it to go to other stars, that's a serious upside! You send it on a hyperrelativistic rocket and time compression will make the Earth-decades-long travel time into a few subjective weeks. So you can start exploring the new star system only a few weeks after launch! Sure, it is decades in the future, but you don't care as it is even further away in light-years. **Problems start once time-drifted ends move closer** than that. You may create paradoxes, but it is suspected by many that this won't actually work: if a photon can make it back to its starting point, it could theoretically follow the same path again at the same time - infinite recursion! And assuming the Universe doesn't CTD with a stack overflow (after all, it hasn't until now and at least *some* idiot alien has to have tried at some point), then **quantum fluctuations will probably crash the wormhole** instead. **What happens when a wormhole crashes? Both ends turn into black holes** of their respective masses. Those are probably small enough to not start eating stuff (after all, you were using them, and a too heavy one wouldn't have been practical to keep one at the surface of the planet. But light black holes pose another risk: [**Hawking radiation**](https://en.wikipedia.org/wiki/Hawking_radiation). So your black hole will turn their entire mass into energy in short order - hours, seconds or even less. The last second will look like a giant nuclear test. Probably a subterranean one, as at this point it has probably destroyed whatever kept it from falling and it is too small to care about normal matter. The bad news is, you don't want to do loops. You could, if you are very careful, but it's probably not worth it. Better have a star network, with you at the centre of the star, getting obscenely rich by controlling the flux of everything between the branches! The good news is, if someone else is starting their own branch, you can reinforce your own network and throw a wormhole end their way, to create a closed timelike loop. If everything goes as planned, a wormhole somewhere in their branch will crash and you just stole half their network! Locals may be unhappy about being suddenly forty years in the future, but that's what riot control drones are for. Dr Luke Campbell, in his hard-SF [Vergeworlds](http://panoptesv.com/RPGs/Settings/VergeWorlds/TheVerge.php) setting (which I -shamelessly ripped off- was inspired by for this answer) dubbed this "[**causality attack**](http://panoptesv.com/RPGs/Settings/VergeWorlds/VergeHistory.php#IntraWormholeWarfare)". If you want to look at what wormhole use would look like, definitely check it out. [Answer] **Consider turning your portal into a Virtual [Space Elevator](https://en.wikipedia.org/wiki/Space_elevator)** If I understand your description correctly, then your portal is "stationary" relative to Earth's center, but it's moving relative to Earth's surface. It's also orbiting the sun in lockstep with earth. This means that either the portal is located in an Earth-sun Lagrange point (L1 or L2) or the portal itself is using some kind of advanced anti-gravity mechanism. However, the portal on the surface in its location relative to the surface in lockstep with Earth's rotation. So, why not place the end of the portal in Geosynchronous orbit and so your launch window becomes 24h? Unfortunately, based on [Fay Suggers' answer and comments](https://worldbuilding.stackexchange.com/a/138059/56286), you don't get the "Free momentum" that you earn from a real space elevator as the payload is lifted and brought back to earth. To compensate you will need an evacuated launch tube/vac-train similar to those used in a [StarTram](https://en.wikipedia.org/wiki/StarTram) but without the floating megastructure. (The train will still be several dozen or hundreds of miles long, in a straight line, to maintain survivable G-forces! Small, circular tracks are *not* survivable!) Gravity Assists against earth may also help gain some extra speed. To return back to the surface safetly, the tried-and-true method of [Atmospheric re-entry](https://en.wikipedia.org/wiki/Atmospheric_entry) will be needed. (Again, this is based on [Fay Suggers' answer and comments](https://worldbuilding.stackexchange.com/a/138059/56286).) ]
[Question] [ Wyverns in this world are intelligent creatures (similar to humans), capable of communicating among themselves. [![enter image description here](https://i.stack.imgur.com/0or8I.jpg)](https://i.stack.imgur.com/0or8I.jpg) They are reptilians, cold blood, with hands capable of manipulating, and wings that, at most, let them glide. They coevolved with humans, and have a similar diet to them. That led to several fights and wars for territory and remaining the apex predator of an area. Wyverns are also good swimmers and a good way to go near human encampments is through water. Given that, **which kind of weapons and armors would Wyverns develop?** I'm mostly interested in the weapons they'd use in a medieval age technology where gunpowder hasn't been discovered. [Answer] I'm relying heavily on the posted image, because the answer really depends on your wyern's physical characteristics. We seem to be dealing with a bulky wyvern: strong, with a nasty-looking club for a tail and nice wide wings with clawed hands at the ends. Your spiked ridge along the spine is unfortunate for any idea of riders, but not insurmountable if you get creative. Not that I can see how these could fly at all (not with the pesky square-cube law being the bane of dragons everywhere), but you concede that they won't be doing more than gliding; I'll assume they can leap high enough to glide for at least a couple of seconds on level ground, even if they can't actively gain altitude without very favourable wind patterns and a good launching point. Given their general build, close formation fighting would be absurdity. You won't be getting any good shield walls here: their bodies just won't be able to make a tight formation effectively (what with the wings and tail doomed to stick out everywhere, which will likely move on instinct as well as on command), never mind that they don't look like they could hold a suitably oversized shield very well. However, you do have a promising basis for individual juggernauts, or cavalry squads if they can move quickly enough (I'll assume they can, or they would make lousy hunters in nature). If the terrain is favourable, you'll also have a sound basis for hit-and-run tactics with bows or diving strikes from above. **Juggernauts** For a juggernaut, you'd want nice solid armor. Full plate would be extremely expensive and difficult to make in a way that would be effective, so I'd suggest chain mail instead as the baseline, and plate armor only for critical points. A nice thick layer of that, and the dragon's body will be pretty close to impervious: armoring the wings with that isn't practical unless they can fold in enough to let the body armor pin them against the body (which would be problematic for other reasons), but punctures in the wings shouldn't lead to fatal blood loss. More practical would be a protective lining along the wing edges to deter blades trying to cut into them. You could add a few spikes to that lining and make the wings into very nasty sweeping weapons, but that depends on if the wings could handle the force needed to cut through potentially several humans at once (or at least to rebound with minimal damage if they hit more than they can cut through); if they can't, trying to scythe through enemies would cause horrendous damage to the wings or even rip them off entirely. Whether or not that knife-wing idea would be viable, your probable weapon would be an axe or sword. Their wing-hands look badly arranged for effective use of a spear, and those are mostly anti-cavalry in any case (I'm assuming your wyverns are at least the match of a horse in size and strength, rendering anti-cavalry weaponry unnecessary). A sword gives you more maneuverability, and you'd last longer in a fight before tiring, but the weight of an axe-head could let you chop through multiple foes in one heavy swing if your wyverns can put enough force behind it. The tail would make an excellent bludgeon, although if you're using it you'd better keep a little distance from your allies. Add some sharp edges if you like, to make sure it can cut through things instead of just breaking bones, but that tail doesn't seem to have the maneuverability to focus on using the tip: it's a blunt instrument, so wield (and ideally armor) it accordingly. These would be individual fighters: certainly with more than one on the field at a time, but as I pointed out earlier these wyverns won't do well in formations. They'd be vulnerable to being surrounded and dying of a thousand cuts, but a few of these would smash a shield wall to pieces by sheer force. I think it goes without saying that these guys will be lucky to glide anywhere without hitting the ground hard enough to break bones, so they will be firmly grounded. **Cavalry Squads** There are various kinds of cavalry: shock, light, lancer, and probably a dozen more that I can't recall. Covering shock cavalry here would probably get you some minor variation on the juggernauts, so let's try light cavalry instead. Chain mail is going to be too heavy to allow a high speed; it might be added to reinforce key weak points, but leather is your probable choice for armor. The knife-wings I mentioned earlier, if viable, would be an excellent idea here: cavalry wyverns won't be charging head-on into tight formations unless they have a death wish, but those would do horrific damage if they flanked a group successfully. For weapons, you probably want a good long sword. A standard spear would be ill-advised, but lances with their reach would be useful for a devastating charge as long as you remember that they were a liability in close combat. You would either charge-retreat-charge-retreat in a cycle, or charge once and discard the lances in favor of swords for the ensuing fight in close quarters; the latter would recommend heavier armor, because at that point you basically have shock cavalry. **Raiders** Little to no armor would be advisable here, since you need to maximize speed and agility. If you have lightweight silk available in great quantities to stop arrows, great, but that would be hideously expensive. Wing protection would only weigh them down, and these guys will want the option to glide away. Bows will be your weapon of choice here. If they have the strength and training, I would advise the longbow or a similar weapon, but those were not mastered quickly: the famed English longbow often required years to build the necessary muscle strength and stamina to use it effectively, to the point where it was at one time a [royal decree](https://en.wikipedia.org/wiki/English_longbow#Training) that all men had to train with bows regularly. Still, it would fit their stature (I'm assuming that your wyverns are at least the size of a horse), and that weapon did not gain its fame without good reason. If you doubt your wyverns would on average be capable of using the thing, crossbows have the firepower to make a good second pick; slow to reload, but if you are harassing a slower enemy that doesn't matter much. Tactics would be straightforward: your wyverns would be using their greater speed to fire and withdraw, picking away at the enemy's strength over the course of an advance. If your wyverns can manage greater draw-weights for bows than humans, all the better: you'll have more range. If the terrain is suitable (the enemy is marching through a narrow valley, ideally, but in general anything with high hills or mountains will be useful), gliding down and firing from above would cause tremendous disruption without any real risk; bonus points if your wyverns have some equivalent to Greek fire or napalm together with a few fire arrows. [Answer] Lightweight ones. One of the key advantages that Wyverns have over Humans is that they can fly. Another that you have states is their swimming capabilities - allowing them to approach Human settlements underwater (to counter which, humans would build pillars in the river upstream and downstream the river - forcing the wyverns to surface at those points, or break the pillar, both of which the Human guards can see from a distance) Any heavy, bulky armour or weapons will inhibit both of these advantages, and potentially allow Humans to usurp Wyverns as the Apex Predator. Another consideration - as Wyverns are cold-blooded, they may emphasise *warmth* over *protection*, allowing them to operate on cold nights. Fluffy jumpers, yes. Plate armour, no. [Answer] **Bombing Runs** The best fliers could drop those around human's troops to make it hard for the humans to move around, similarly they could drop incendiary devices or even infected animal corpses. **Artillery** Their hands and body position would make it hard to use bows, but maybe something similar to crossbows could be used, with the weapon mounted on their backs with special harnesses. **Hand-to-hand** Using swords or lances wouldn't be pratical because of their body shape, instead of fighting with their hands they would prefer to use their mouths and legs, probably with something similar to the Cock's spur they use in chicken fights. In fact their ground fighting would resemble a lot the moves of a chicken. [![Metal Spur used in cockfighting](https://i.stack.imgur.com/S9o3M.jpg)](https://i.stack.imgur.com/S9o3M.jpg) [Answer] **Wings** Blades protruding around the edges of the wings could give a wyvern essentially a massive fan of knives. Flaring the wings from folded to spread would flick with the blades at their opponent with a long reach and coverage all around the wyverns body. Something kind of like this (but with blades on): <https://makeagif.com/gif/victorias-riflebird-bird-of-paradise-dance-XGjD5y> . The wings whirling and flicking would also be visually confusing and difficult to follow, similar to how some kung-fu movies have female fighters swirl their dress in front of their opponents to conceal attacks. This weapon could also potentially be used in gliding attacks, slashing enemies as the wyvern glides past. But viability for something like this is dependent on how much fine control they have over their wings and how strong they are, and may require some kind of struts or something along the wing spines to give additional strength and support to the wing bones. **Tail** The tail seems like a natural weapon with huge reach. But again it depends on how strong and finely controlled it is to determine how it can be used. If it is strong enough to mount a decent sized spike on the end it could make a powerful piercing weapon for use against heavy armour, or the whole tail and end could be armoured and used like a mace (like an ankylosaurus). Also, in many traditional depictions of wyverns they have a venomous barb on their tail; this might be something that could be incorporated to provide a nice synergy with traditional lore. A poison spike is more suited to fast, light attacks rather than heavy armour penetrating ones. **Feet** See the cock fighting blades in Sasha's answer, something like that would be devastating for use if opponents get up close where it's difficult to use the wings and tail. **Combat** So I could imagine lighter wyvern troops that are armed with the wing blades and poison tails that are suited to skirmishing and ambushes, fighting other lightly armoured opponents and making use of gliding and swimming where possible. Then heavy wyvern troops would probably use tails as their primary weapon, perhaps covering their wings with armoured plates to provide heavy protection for themselves and other troops. Wyverns would need a fair amount of individual space to use their wings and tails like this so would probably fight in loose formations, although heavy troops with armoured wings may be able to close ranks to form a shield wall. Humans would probably want to fight them in tight formations to limit their sweeping movements and isolate them in 1 against many fights. [Answer] These wyverns you describe seem built for speed, chasing down prey using their wings as aids for running more than flying (I'm thinking something akin to prehistoric terror birds). Scouts are likely going to be very lightly armoured (if it all) with weapons that wouldn't interfere with their speed, likely augmentations of their natural weapons like metal barbs attached to their tails and feet. These creatures aren't built to fight in a shield wall, but they are built to break one. They don't look like they could bunch up behind a shield wall to give the necessary weight to push an enemy shield wall back or break though it. It's also likely that they are hollow boned, so light for their size. But a couple of wyverns with rams or large spears tucked under their wings could probably do some damage running straight at a shield wall, of trying to jump over the front row of shields (humans would likely form shield turtles to try and combat this). Armour for infantry type units would likely have armour around their chests and backs made of chain, plate, leather or whatever the individual can afford. Some may have additional protection for their wings and tails, more likely leather or cloth as to not overly restrict movement. Their siege warfare tactics could use siege weapons where they are the payloads, being fired into the air to glide into enemy compounds. Not being able to form an effective shield wall would put wyverns at a disadvantage when on the defense, so I envisage them concentrating on keeping attackers at a range (large spears and crossbows) and/or picking defensive positions where they could mount a good offence like large open spaces where they have the high ground. [Answer] **Saddles. Stirrups. Flying cavalry.** <https://en.wikipedia.org/wiki/Saddle> > > The development of the solid saddle tree was significant; it raised > the rider above the horse's back, and distributed the rider's weight > on either side of the animal's spine instead of pinpointing pressure > at the rider's seat bones, reducing the pressure (force per unit area) > on any one part of the horse's back, thus greatly increasing the > comfort of the horse and prolonging its useful life... The stirrup > appeared to be in widespread use across China by 477 AD,[15] and later > spread to Europe. This invention gave great support for the rider, and > was essential in later warfare. > > > Your wyverns can fly but their hands are integral to their wings. While using their wings they will be less able or perhaps unable to do anything complicated with their hands. But (I here assert) your wyverns are not all the same size. Maybe the females are a lot larger than the males, or maybe there are juveniles or youths who are smaller than the huge adults. A saddle will let a small wyvern ride a large wyvern. Now you have flying cavalry with intelligent mounts and that has awesome potential. A flying rider with a lance or slashing spear would be a formidable opponent against an earthbound human. A phalanx of these would be unstoppable by any human armed formations. There would be no real way for humans to combat archers gliding back and forth at 50 meters. ]
[Question] [ **What realistic mechanism could be utilized to allow my drone to hover and move around in a visually pleasing and non distracting way?** I am currently working on a short sci-fi film, which, among other things, includes maintenance drones that will be present on a space ship. My goal is to have a fair amount of realism. (There are certain things, like FTL and ship-wide artificial gravity that will be hand-waved, but besides that I want to incorporate as much science as possible.) The drones are designed to operate on a civilian transport ship (basically a combination of a cruise ship and a commercial airplane) where they provide repairs, aid passengers, and just generally maintain the ship. (They do also happen to be useful for taking care of unwanted guests, if you catch my drift...) They need to be able to move freely anywhere in the ship, at any height, and at a relatively fast speed, while still looking cool and not being extremely distracting, without any obtrusive propellers or exhausts, using a scientifically plausible method of propulsion. --- ## The Drone: The main body is round, about the size of a basketball, and made of some kind of durable composite. I don't have any particular material in mind, so feel free to use what every might be necessary. The bottom half of the drone has multiple mechanical arms, (most likely 2 - 4) with different tools and gadgets. This is also where I assume the hovering system would be located. The top half has various sensors and lights. The exact weight isn't important, but it should be enough to make a sizable clank when it hits the ground. --- ## The Ship: The exact details of the ship shouldn't be too important, but here is some basic information. The ship is around 0.5km tall, and 2km long. Of course, not all of this will be habitable, but there is still more than enough space for hundreds of drones to be at work. Any area inside the ship will have near perfect artificial gravity, and otherwise be identical to earth as far things like air pressure and temperature are concerned. --- ## Specifications: Here is a list of all the requirements the propulsion system should meet. Some exceptions can be allowed, but the system should be as close as possible to these specifications. * The drone should to be able to hover in place for at least a 30 seconds. * It should be capable of traveling at least 20mph, although 50mph would be more desirable. * It needs to be maneuverable and capable of quickly changing direction. * It needs to be capable of functioning in the ideal conditions for human habitation. (As in: temperature, atmosphere, etc.) The ability to operate at higher temperatures would also be welcome. * It has to be safe to use around humans; no radiation or excessive heat. * It needs to be usable in close proximity to at least 3 other drones using the same system. (Ideally there should be no limit.) * It should be able to move freely anywhere on the ship, without being confined to certain areas. If a specific component is required in the drone's environment, it has to be easily implementable throughout the ship. * It needs to be quiet. Some small, sci-fi-y noise is acceptable, but nothing that will drown out any dialogue. * It can't be bright or distracting. It's fine if there is no visual indication of any propulsion, but it would certainly be nice if it had some cool effects. (I will be animating this.) There can be no huge rocket thrusters, or propellers. This isn't a quadcopter. Something small, that's visible but not eye-popping would be ideal. --- **Some things to note:** * The ship itself may have artificial gravity, but this can not be utilized for the drone. (The idea is that the ship has some gigantic power source, unlike the drone.) * The drones will also operate outside the ship in the vacuum. Some simple RCS thrusters should suffice, but it would be a bonus if the mechanism also works in space. --- Is there a plausible propulsion system that suits my needs? [Answer] You can use ionocraft lifter, formally [*electro-hydrodynamic thrust*](https://newatlas.com/mit-ionocraft/26908/) like the one seen, for example, here: <https://www.instructables.com/id/High-Voltage-Lifter-Ionocraft/> - yes, you can build one, too! > > It works by using an negative anode to charge air particles. These charged particles or ions are drawn down to a positively charged cathode. As the ions move toward the cathode, they bump into other air molecules and push them down, creating the ionic wind. > > > Only drawback, but potentially aestheticslly pleasing, is that your drones can send dust or paper flying, and may make balloons stick to walls, if some ions escape. In space this would obviously not work, because it uses air as reaction mass. Still, this ionocraft engine can use rcs exhaust as its reaction mass, making them noticeably stronger, and thus saving chemical fuel that's probably harder for you to replenish than electricity. As for drones operating next to each other, there is no limit, except maybe don't let a drone take in exhaust of another one. Only thing that's not quite doable right now is on-board power source, but we are getting better at that, so you can believably ignore it. --- Note: If you will allow discharge to happen, you will have nice blue light (SF classic!) but also O3 and NO2 production. In smaller quantities, ships scrubbers can probably deal with them. In larger these may cause adverse health effects and corrosion. Thus, I'd suggest limiting it for emergency, and operation outside hull. [Answer] Quantum levitation. Get a superconductor close to a magnetic field and you get some really cinematographic effects, though in real life. ![Weeeeeee!!1!](https://i.stack.imgur.com/dlORe.gif) ![Quantum = sciency magic](https://i.stack.imgur.com/O03YS.gif) You're seeing smoke because superconductors nowadays mostly exist in very cold temperatures. I mean liquid nitrogen cold. Every nerd who knows their materials dreams of the day we will have cheap, viable room temperature superconductors, which would be non-smoky and wouln't give you ice burns. Anyway, these things will hover over tracks defined by magnetic fields. I believe that if you are doing FTL, it should be trivial to manipulate such fields, inside and outside the ship. Last but not least, [the science for this form of levitation has been known from since 1933](https://en.wikipedia.org/wiki/Meissner_effect), so it's no strerch at all seeing it applied for ordinary things such as drones in the future. [Answer] Now, I know you said "not a Quadcoptor" - but you also said "The main body is round, about the size of a basketball". So, put the propellers (or *imp*ellers?) **inside** the casing, with vents to take air in the top, and push it out the bottom. Then, for manoeuvring, have pulsed jets of compressed air, arranged around the drone (like the training drone in the original Star Wars!). As the drone travels, it will generate a characteristic "phut-phut" noise, to go with the whirring-drone of the propellers/impellers. It can push in any direction - multiple pulses will keep it going in one direction - since air resistance will try to slow it down, and faster pulses will make it travel faster. The pulse of compressed air can cause a visual effect - the refractive index of the air is changed, you may get water vapour because the gas is cold, etc. While inside the ship, it can run a miniature compressor to suck in and store air, so it is limited only by power (And will add *yet another* noise that the drones sometimes make - it may even pause and hover or land/dock while it does this, possibly with lights to indicate that it has low manoeuvrability). While *outside* the ship, it will have a limited air supply - but also no air resistance or gravity to contend with, so a single pulse can carry it as far as it needs to go. The propellers/impellers inside can then be used as gyroscopic reaction wheels, to allow turning without expending air. It may have an emergency supply of very compressed gas that can be swapped out when it returns to the ship, at whatever docking station it uses to recharge. [Answer] **Gravity tech.** /ship-wide artificial gravity that will be hand-waved/ There you go! And you only needed to wave your hands once, so you didn't get all sweaty. Your gravity tech is granular. It is not generated centrally for the whole ship, but cell by cell across the floor, just as a series of rooms might be illuminated 1 room at a time. That conserves power; gravity is produced where people need it and where circumstances require (like a swimming pool) but no energy is wasted making gravity for an empty room. Your drones leverage this tech. They have gravity capable cells in them. They orient and turn on the cells as needed, essentially pulling themselves through the air against the mass of the ship. Ships gravity under the drones will be off as they pass by, but the drones might choose to produce their own gravity to pull them closer to the ceiling or down to the floor. This would affect items in the vicinity of the drones as well, giving an effect similar to a gust of wind even though a drone might not be moving fast. Having your gravity tech portable and granular like this also offers narrative potential. If a drone can pull itself, a tethered drone (or one which anchors itself) can attract a distant object by ramping up the gravity pointing that way. [Answer] ## Anti-Gravity Before I get into it, let me clarify: What would be plausible technology in the Middle Ages? Metallic boxes running on some parts of oil via combustion (or short: cars) would be unthinkable to these times. So instead of attempting to apply *currently known, but not sufficiently explored* technology to a futuristic, fictional world, let's try to create something that is sufficiently plausible and on par with let's say FTL and, **as in the question mentioned**, artificial gravity. One metric which is important is consistency and keeping basic physical laws applied. How would it work? Similarly to electro-magnetism, but with gravity instead and also reversed. It would be a module which could exert anti-gravitational forces if powered by electricity and which exerts force in a direction opposite to the current gravity. Now, gravity itself however is not just a force. It's a phenomenon which bends space (and time) in a way that for example stellar objects can orbit each other. Now, the anti-gravity module has the opposite effect - it bends space (and time) backwards in a relatively small, confined space, so that the space-time bending of gravity causes the drone to move upwards instead by being repelled. There would be a constant value which could entirely negate gravity, and anything above that would cause it to have opposite effects. This effect would work gradually, meaning a drone has to continually adjust the efficiency in order to either move downwards, upwards or remain still. That goes also for moving horizontally - which could be achieved by simply using the anti-gravity module asymmetrically so that a part of the drone "falls" in the direction it intends to hover. This navigation requires a sophisticated AI in order to work properly, but that exists today already for normal drones. The energy required for the module depends on the volume and mass of the drone and the magnitude of gravity it is in. But to what is the energy actually converted? Repulsion! It may defy gravity through its workings, but at the same time it would also push away whatever is exerting gravity to it. This means practically that the floor/artificial gravity modules would still have to carry their weight. The surplus energy, which couldn't be used effectively, would result in some heat which may require cooling. **Upsides:** It could directly convert energy into propulsion without the need for fuel. The device would be harmless. It wouldn't require a lot of energy and the energy conversion could be much higher than that of fuel for example. **Downsides:** It could not be used for space flight because it would be dependent on gravity and be too weak in general (navigation would be near impossible). It would be no easy tech, maintenance would require quite some technical knowledge and complex parts. Note: Usage for vehicles on a planet are feasible, but quite sluggish to navigate in - braking would be the most difficult part as it would work the same as forward thrust, not like cars which use brake based on friction. Remember, it would not repel matter, only sources of gravity. That said, this propulsion might not be the only one used, but might get complementary methods or tech to accommodate for its shortcomings. [Answer] I know you want a flying drone, but I feel like this idea could do roughly the same BB8 Drones with an extra magnetic connector so it can travel around on the walls, roof and floor. Whether its avoiding crowds or getting to hard to reach places, BB8 can do it. BB8 is round and adorable BB8 is a multiple purpose drone. Multiple grappling hooks, a torch and a terminal plugallow BB8 to be an all purpose maintenance bot and a deadly adversary. BB8 is safe and friendly. No deadly rotor blades or thrusters that could hurt potential customers. BB8 is also environmentally friendly, running off a battery powered motor. ]
[Question] [ I looked for answers, but didn't see any solid answers for this particular question. Unlike the other questions my winged humanoids can have their wings disappear so they can pass for human, then have them "grow"out of their body in seconds when they wish to fly. In summer there's not as much problems for these humanoids to extend their wings. Males can wear the right loose tank top with lots of space near the armpits and extend their wings without problems and there's plenty of backless clothing female winged humanoids could carry with the right bra choice. Outside of summer it becomes difficult as I think there's little to no clothing that can pass for normal and still allow the winged humanoid to extend it's wing and fly when in a pinch (or when it assumes it's wings and flight won't be seen by people who would be alarmed). Assuming the humanoids have access to tailors (who know about winged humanoids) that can change regular clothing to fit their needs, how would they change their clothing so as to have the full benefit of the clothing and wings? About the wings: The wingspan is large, let's say a single extended wing has 1,5 times the length of an extended arm (if that's too little surface area make it larger). Growing the wings back happens at a speed the humanoid determines, but at a maximum speed of 3 seconds. It'll simply grow from a tiny thing attached to the shoulderblades and eventually be attached to the shoulderblades (ignoring the massive extended chestbone you would need to flap the wings) and the spine. The humanoid has full control of the wings during growth and can try to push them through something if possible. My only idea so far was to have 2 seams run along the back around the shoulderblades. These seams cover up a zipper opening with flaps around both sides (inside and out) of the zipper to keep the wings out and make it comfortable to wear. If they want to extend their wings, they reach around their back into the seam, open the zipper and then take off. Zippers would probably not be a great idea since they would probably chafe and damage the wings no end when growing and flying, but using buttons or similar would likely not close off the back enough to keep out rain or cold wind. [Answer] Depending on your setting, capes or ponchos could work quite well as warm, potentially water-resistant, items of clothing that would allow freedom of movement for wings. However, to stay nice and warm, I’d recommend a decent thermal vest to be worn underneath clothing at all times (something with enough open space around the shoulderblades not to hamper movement), and then some form of tailored jacket, coat, or sweater as you mentioned in your question. Buttons can work very well as a fastening option, even in colder climes - simply line the seam with some thick, furry fabric. When the jacket is closed, the fur meshes comfortably over the gap and keeps the wearer warm; when the buttons are unfastened, the fur still keeps the wearer’s shoulder blades warm, while also providing a comfortable surface for the wings to move against. Other fastening options could include poppers (again, you’d want a fluffy lining to offset any friction from uncomfortable metal edges), Velcro (you’d want to double the Velcro on one side at least, so you could fold back the scratchy side and have it adhere to another strip out of the way, so your wings wouldn’t get friction burns), or even laces (which would obviate issues of friction - you’d simply remove them and use them to tie your lovely flowing hair out of the way, and they’d lace tight enough to keep the wearer nice and warm). Laces might also have an added fashion benefit, if your characters are interested in such things, potentially looking corset-like if laced loosely. Equally, you could lace it up tightly enough that the lacing would be all but invisible. Another option would be to have your characters wear thick, long scarves. These scarves could drape down low enough at the back to keep shoulderblades warm and covered, and any open fabric wouldn’t be a problem when cold. As per clothing advice for normal humans: layers are good! [Answer] **Drover coat.** [![enter image description here](https://i.stack.imgur.com/bBKTL.jpg)](https://i.stack.imgur.com/bBKTL.jpg) <https://www.downunderweb.com/shop-all/mens-drover-jacket-oilskin-western-duster-3-4-length-1/> <https://www.folkwear.com/products/copy-of-137-australian-drovers-coat?variant=36841680142> These are work coats popular in the American west and especially Australia. They have a capelike piece on the back. Google them up - you can find heavier wool versions for colder weather. An exaggerated cape attachment could cover folded wings on the back and it would look cool. --- **Serape** Or you could just go ahead and give them capes - probably more properly "serapes" since these are substantial and practical garments, not superhero regalia. I see people in cape looking wearable blanket things all the time, including across from me at breakfast this morning. Clint is looking pretty good in his serape from The Good the Bad and the Ugly. The runway model looks even better although not that warm. [![clint and model;](https://i.stack.imgur.com/t4FBK.jpg)](https://i.stack.imgur.com/t4FBK.jpg) <https://www.halloweenforum.com/halloween-costume-ideas/78725-eastwoods-blondie-good-bad-ugly.html> <https://www.nytimes.com/2009/10/07/fashion/07DRESS.html> [Answer] The simplest would be to wear the usual backless/tank top and then put a loose coat, hoody or cardigan over it. When they need to fly they can very quickly pull off the outer layer and extend the wings. The problem with this is that they may get cold while flying, in order to avoid that they can wear a warm layer with the space cut out for the wings then wear a thin item over it to conceal the holes. Something that won't be seen as too strange when worn indoors would be good, to avoid needing to explain the holes when removing it! [Answer] First, there's detached sleeves. [![enter image description here](https://i.stack.imgur.com/80mpY.jpg)](https://i.stack.imgur.com/80mpY.jpg) All of the tankiness of a tank top, but with sleeves. At the very least, this can form a basis for your layering. After that, for the top layer, a poncho-like structure might be best, if it's designed simply. The serape that WillK recommends would be good to pair with a detached sleeve base. With this combo, you would not be able to tell the shoulders were bare. Scarves draped lower as K. Price suggests would also go well with this base. [Answer] **They have feathers and disguise themselves by covering them up with clothing.** I suspect that they would have to have feathers. If they fly to any appreciable altitude it's going to be cold up there. Surely they won't have evolved to have bare skin. > > ... the temperature decreases by about 5.4°F for every 1,000 feet up > you go in elevation. > > > <https://www.onthesnow.com/news/a/15157/does-elevation-affect-temperature> > > > The above is true in clear air even in Summer. It's much worse in bad conditions. I suggest they simply disguise their feathers as fashionable clothing. Maybe they pretend to belong to a particular arty movement. Or they could cover their feathers with light opaque clothes. In an emergency they simply disrobe and take off. [![enter image description here](https://i.stack.imgur.com/Ge3FB.png)](https://i.stack.imgur.com/Ge3FB.png) The clothing would have to be designed like that used by male-strippers for quick removal. [![enter image description here](https://i.stack.imgur.com/L8c3E.png)](https://i.stack.imgur.com/L8c3E.png) [Answer] Have hinged winged slots in the clothing itself. For clarification, have a piece of fabric mounted on a hinge mounting sown to the fabric, in normal day to day activity, it sits flat against clothing, looks just like any other portion of clothing, they grow their wings, wings come out of openings in the clothing push the hinged portion aside, and still have room to work the way they're supposed to. ]
[Question] [ Essentially, this is a sort of brainstorming question: Say a world has many kingdoms and cultures, and each of these have magicians who can use magic, which includes things like improving physical strength and casting fireballs and the like. The knowledge that magic exists is widespread and, while perhaps not a part of daily life for many in the lower castes, generally accepted as fact considering its constant use in warfare and in the upper echelons of various societies. In this world, each Kingdom favors a different sort of magic. Say one kingdom's people are more naturally adept in focusing the power of the elements, another has magicians that are more naturally skilled in psychic/telekinetic abilities, another has magicians that are naturally skilled in raising the dead, etc. That being said, would the Religions necessarily be related to their favored magic, considering the very nature of magic being the ability for human beings to do things that defy the laws of physics and reality? What sorts of situations might lead to there being religions in different kingdoms that are in no way or only marginally related to the magic that they favor? To summarize: *In a world where different kingdoms exist and each use magic that allows them to control and manipulate different powers, would each of said kingdoms have to have religions that are related to the magic they favor? What conditions might exist that result in religions completely or mostly unrelated to their magic?* [Answer] # The Accoutrements Of Daily Life Add Color But Not Meaning > > That being said, would the Religions necessarily be related to their > favored magic, considering the very nature of magic being the ability > for human beings to do things that defy the laws of physics and > reality? > > > This is the weak chain in the link. There is no reason for this to be the case, anymore than religions in our world have any relationship to science and engineering. Nobody goes to the Church of Newton (unless you live in Newton, MA). While religions reflect their adherent's understandings of their world and their way of life, that doesn't mean that people worship the ordinary things that they deal with on a day to day basis. The ceremonies by which people celebrate their religions may incorporate almost thoughtlessly, local magic. People who can remotely light candles are not going to have six foot candle lighting rods sitting around their temple sanctuaries, and if they do a lot of fire magic, they may choose to decorate in non-flammable materials. People who can levitate probably aren't going to have a staircase to the pulpit. But, these local innovations may not even been seen as having religious dimensions to them, any more than people who put aluminum siding on their church in our world because that is a material that is expedient and easily available do so because there is anything inherently sacred about aluminum siding. The more infused daily life is with magic, the less likely it is to have religious significance. To understand a religion one should look to its members needs emotionally, to the uncertainties and triumphs they face as a community and as families within that community. What are the defining events in the lives of people in this religion? What are their greatest fears? What events trigger emotional highs and lows? Identify those and there will be rituals and prayers centered around them. Some could be magical in nature. If you come into your magical capacity or identify your magical specialty at some age, that could be celebrated in a coming of age ritual. If people have magical power that varies from time to time in an emotionally relevant way, for example, leaving you deeply depressed after using a lot of it, there might be some personal rite by which the religion helps people deal with it (perhaps analogous to the Roman Catholic practice of private confession of sins). Birth, marriage, and death will be important in every culture. Know your world and you will know what has meaning to people, and hence, what the religion will have rites to help people cope with in their lives. # Religion Evolves with the Scale of a Society's Political Economy Historically, a fairly common succession of religious world views goes from animism (somewhat naturally arising out of an anthropic view of the world from the perspective of a hunter-gatherer), to not necessarily very human-like gods (at the Neolithic transition), to ancestor worship, to polytheism (paralleling the political world of a chiefdom or small state as individual divine ancestors become shared divine ancestors), to monotheism (paralleling the large universalist bureaucratic state), with intermediate stages along the way. Consider where your religion is on its path, where it came from, and which stage it will be heading towards next. A society fresh out of a polytheistic stage to a monotheistic one may have lots of revered saints to smooth over the transition. A sect of a more mature monotheistic sect, like the Puritans, may seek to tear away all of those residual elements used to make the last transition so as to purify the faith of its heretical antecedents. It can get slippery. The animal sacrificing Temple Judaism of the ancient Hebrews, for example, would be barely recognizable to a modern adherent to Rabbinical Judaism, even though, there is an ancestor-descendant relationship between the two phases of the Jewish religion which has not fully rejected its earlier traditions, and even though they are religions known by the same name. # Metaphysical Worlds Mirror Contemporary Political Structures In addition to following an evolutionary path somewhat related to the political and economic structure of the world where it exists, the organization of a religion's metaphysical world tends to echo the political structure of a world, because most people aren't all that creative when it gets down to it, when it comes to imaging other possible worlds. If people live in rival kingdoms, the metaphysics of their religions probably have a royalist perspective with different kingdoms (perhaps heaven, purgatory and hell, or more), in the divine world. # Religions Fixate On Norms Needed For Community Survival Religions reflect the values and norms its people think are critical to their culture's continued existence as of their formative period. The ancient Egyptian religion placed the maintenance of a firmly legitimate dynasty rooted in the annual rhythms of the Nile above all else because this is what made their continued existence as a civilization possible. Confucian philosophy's focus on hierarchy and order met the needs of a society sundered by lawless feuding warlords who destroy each other in struggles for power and barbarian raids, who need to be unified by clear lines of authority in order to maintain internal peace and repel invasions. The earliest portions of Old Testament Judaism and early Islam reflect the values of people living a nomadic herder life, where a culture of honor is necessary for survival and harsh punishments are the only option because the community doesn't have the resources to maintain jails and prisons. Temple Judaism reflects the needs of a newly urbanized group of people who have transitioned from nomadic herding, to sedentary farming (and the Temple designs are classic megalithic astronomy devices useful for managing crop cycles). Rabbinical Judaism elevated literacy, scholarship and ritual observance to supreme values in the face of an urgent need to preserve the community's tradition and intellectual existence while cast to the four winds in small diaspora communities. Christianity brought norms that tended to the needs of an intensely urban society of merchants and craftsmen living cheek by jowl, in which an underlying theme of forgiveness served the community better than a culture of honor that turns slights into blood feuds. The moral creed of the Methodists of the First Great Awakening in the United States focused on providing its parishioners with bonds as fellow members of mutually supportive communities who needed each other, each and every one, as pioneers in the wilderness. The Evangelical Christianity in the American South that arose in the Second Great Awakening cemented the values and attitudes its members felt they needed to maintain a slave labor based society. If you want to create an authentic feeling religion for these magical people, ask yourself what norms this community needs to drag its people into in order to face its most urgent challenges better. Stick to just one core norm or perhaps a mysterious give and take of a couple contrasting norms that must be balanced like mercy and justice. Is the existential threat these communities face infighting? Is it a failure to innovate and overcome their rivals? Is it unleashing Pandora's box by being too innovative? Is it the need to work in harmony with other kingdoms, or the need to fight to the death to repeal genocidal invasions? Is it the need to prevent uprisings of the lower castes? Or is it the needs to prevent magical talent from being diluted through out marriage to people who aren't magical? Understand what values the community needs to survive and you have written the homilies and parables that will be taught in the churches and temples and home altar hearths. # Religions Thrive When They Nurture Threatened Cultures Another dimension in thinking about religious world building is how vibrant the religious part of life is in these kingdoms. As a rule of thumb, religions that nourish and are a part of a threatened culture thrive, while religions that merely echo widely held establishment views fall victim to apathy and shallow commitment, even if religious institutions have ample economic resources and state authority at their disposal. Irish Catholic churches, during centuries of oppression at the hands of English Protestants, were vibrant institutions full of earnest and devout parishioners. At the same time, French Catholic churches, continuing centuries of tradition and controlled by senior clergy closely related to local nobility, gathered dust and had lots of vacant pews most of the year. Immigrant churches and, in the U.S., African-American churches of oppressed outsiders thrive, while mainline churches have in recent times after being co-opted and losing their ethnic identity, go through the motions. If there are expatriate communities in these magical kingdoms, you can expect the churches and temples of these foreigners trying to hold onto a sense of home to be better attended and more respected by its members and more strongly supported, than local churches and temples of people who take their culture and faith for granted. [Answer] Sure. Religions could be any sort of thing you want. Take the Amish, for example. They live in a world filled with technology, but they believe that God would rather them not use it. An equivalent might be the Mamish, who live in a world filled with magic, but they believe that God doesn't want them doing magic stuff. Also consider evangelical Christianity. No matter what is happening in the scientific world, many Christians maintain an invisible God who deals with them on a personal level rather than on a scientific one. A good case can be made that for several Christians, God is more about how they feel than what they do or happens in the world around them (whether that is the right way to be Christian or not is another topic). These things happen because religion isn't "just" about supernatural things, or even things that you see in the world around you. It's typically *confirmed* with supernatural things. Organized religions (in the west anyway) are more about authority figures, relationships, and the impact they have on moral considerations and hopes for the afterlife. Basically, yeah, religion could definitely develop which has nothing to do with magic, even in a world where magic is commonplace. [Answer] Your magic sounds like some pretty crazy stuff. It's so crazy that people who don't know much about it or have no knowledge of its use might even worship it. But you know what else is crazy? The sun. Think about it, it's a giant ball of fire that moves regularly through the sky, and only becomes more crazy sounding as you learn more about it. Sure, there are some people who will worship it, but most major religions consider it a **creation**, not a **creator**. So yes, you can have a religion that worships something other than magic, with magic either as a devine gift from their deity, or just another fact of life. [Answer] **Use the "organic" trend as an example.** Think about the "organic" trend. We currently have plenty of chemicals able to make fruits grow bigger and our farm animals better. However, there are people who prefer "natural grown" fruits and animals, even if that means smaller fruits or less meat in the animals (and most of the time with a higher price). They prefer not to consume "enhanced" resources and not to use all that available technology. The same could be applied to a "non-magic" religion in a magical world. That religion will despise the use of magic and will relay on human natural abilities, even if that means giving up all the benefits of the magic. You will need to design a God that prefers the abstinence from magic and provides eternal benefits to the ones that rely on their natural gifts. Even a "Savior from the Magic Chaos that will condemn you". [Answer] > > each Kingdom favors a different sort of magic. > > > Maybe each kingdom has its specific sort of magic due to its location. Some regions may provide natural magic power of levitation, others provide fire magic. What about a region that provides some sort of anti-magic? Where the specific talent of their magicians is to disable magic spells? Maybe they don't see this (anti-)magic as a sort of magic, but as the will of god that people should not use magic. Their magicians would not be called magicians but priests. Those priests speaking a prayer that disables magic of others would not be amused if you call them magicians. [Answer] Contrary to popular belief, not all religions are made equal. They're not always about worshipping some great big authority figure who proves his power through supernatural feats (a la monotheistic religions and the Greek/Roman pantheons). In a world where magic is commonplace, I imagine that such religions would be rare, if not absent, due to the fact that magic exists; so at this point we have to look at religion's other purposes. * Moralising and philosophy * Making sense of the world * Control of the masses For these purposes, many faiths would sprout. Where does magic come from? The Gods, of course! Why do rivers ebb and flow at certain times of the year? An angry river spirit who denies water on his bad days. Is it bad to have sex before making a lifelong commitment to a mate? YES! Want to make a society more orderly/repressed? Tell them God wants you to obey and give money to the priestly class! Et cetera, et cetera. There are plenty of religious tenets unrelated to the presence of magical powers in-universe. ]
[Question] [ Assuming there were no extinction level threats to the dinosaurs, and they never fully died off (and survived the following ice ages), how would this affect the evolution and technology use of humans if at all? Given that a T-rex is about the same size and speed as an elephant, and velociraptors are slightly faster than wolves and slower than lions, I presume that we would just handle these dangerous creatures much the same as we handle similar and the major difference would be in fauna and flora. My question is not how would we survive with them as [Could humans survive with dinosaurs?](https://worldbuilding.stackexchange.com/questions/113861/could-humans-survive-with-dinosaurs) answers, but specifically how them surviving would affect our evolution and technology development. The linked question specifically states "Okay, quite a few people have asked what technological level the humans are at. Well these humans were on a generation ship before so I would assume space age level." Where i am asking if humans could develop and if so how would their tech change if at all to deal with these creatures. Very specifically, the other question asks if a pre-existing human civilization could survive if introduced in an environment where Dinosaurs still roamed the Earth. This question is asking if humans could still **EVOLVE** on such a planet, and if so, what major biological and psychological differences might there be on such a planet. [Answer] It is highly unlikely that anything just like us would have evolved had the dinosaurs not gone extinct. Evolution is essentially chaotic (in the technical sense) and is driven by accidental mutation and accidental matings (both driving randomness) and natural selection weakly selecting each of the new genomes created by random mutations and random egg-meets-sperm events. This goes on over millions of generations. Natural selection will still result in highly adapted organisms and may well produce intelligence, but it would be very unlikely to look much like us and certainly would not be human in the biological sense of being interfertile. Would intelligence in any form evolve on a dinosaur-dominated planet? Hard to say because we don't really understand how intelligence evolves or how likely it is to evolve. The evidence is that in our sample of one, it has evolved once in the last hundred million years. This allows us to make a (weak) estimate of intelligence taking on average 100,000,000 years to evolve with *huge* uncertainty. (Not a good estimate, but it's an estimate based on actual evidence rather than speculation.) On the more speculative side, we think that social animals are more likely to evolve intelligence. (Basically, that we evolved intelligence because we lived in troops which started out looking a lot like modern baboon troops, with intense social interaction. We evolved intelligence because it allowed us to lie better and to gain higher social position in the troop. So look for whatever ultimately evolves to come from a social animal. [Answer] The un-fun route is to theorize that larger, intelligent mammals would never have had the chance to develop b/c the dinosaurs would have filled every ecological niche. Alternately, the dominant, human-intelligence life would be reptilian, like the [Sleestack](https://en.wikipedia.org/wiki/List_of_Land_of_the_Lost_characters_and_species#Sleestak). *This could be an entertaining avenue, having fun with presumed differences between humans and humanoid reptilians.* Alternately, mammals and monkeys do evolve, but must be absolute ninjas to survive among the ferocious dinos. The baseline human in this scenario would have to be a full-on Strider level Ranger: able to move silently, hide impeccably, stay upwind of threats, and be stronger, faster and more agile than we contemporary humans. These humans might evolve to be small like [Homo floresiensis](https://en.wikipedia.org/wiki/Homo_floresiensis), to escape the notice of the larger dinosaurs, or, they could evolve from the largest apes, like [Gigantopithecus](https://en.wikipedia.org/wiki/Gigantopithecus) or even larger. You'd likely still need some environmental disaster to open up ecological niches for the alt-human evolution, but the disaster could be smaller scale, perhaps restricted to a single continent like Australia. You could also look to a model where [Yeti](https://en.wikipedia.org/wiki/Yeti) evolve first, since high alpine regions would be inhospitable to many dinosaurs, and humans evolve subsequently from Yeti, losing their hair over millions of years. [Answer] There were several extinction events that could have set the dinosaurs back without killing them off, allowing mammals to have an easier time flourishing for a while. You could have the dinosaurs make a comeback later without wiping out the primates. Humans would likely be faster, perhaps able to still run on all fours to run away from giant predatory dinosaurs or even angry plant eaters. This also means they might have less endurance and would maybe have to eat more plant foods since our endurance irl is unique in the animal kingdom bc we're equipped to run animals to exhaustion. BUT this also means we would have GIANT bellies, which would be required to extract the same amount of nutrition from plant foods as we currently do from meat. This would also lead to humans being less intelligent since the calories required back in the day to support a huge brain would not have been available in plant form. There is one way to get around this - you could also play around with plant evolution, giving humans a calorie dense food source that could replace meat calories, like a tuber perhaps. Only thing is you would have to work out how the humans evolved to out-compete other animals for the same calorie dense food source. Think BEARS. You could also play around with the enzymes humans evolved with, so we could extract calories from things like plant fiber without having to ferment it like a gorilla with a big pot belly. Think termites. Alternatively, going with the running-on-all-fours idea, humans could have developed a more stealth focused hunting strategy, sneaking up on and then running down prey animals, kinda like big cats. Humans would have to be bigger, or at least more muscular and more compact with larger lungs. [Answer] > > Assuming there were no extinction level threats to the dinosaurs, and they never fully died off (and survived the following ice ages), how would this affect the evolution and technology use of humans if at all? > > > If dinosaurs never went extinct, and somehow survived the following ice ages up to the current era, chances are **dinosaurs would have evolved to be the dominant species on Earth.** Most likely, if their evolution was not halted, they will eventually **become Sentient, or develop higher mental functions** like language, maths, arts, etc.. They might also develop a proto-society, which may eventually evolve to villages, cities, metropolis, etc.. As they continue evolving their mental faculties they will become some sort of **Reptilian Race**, now capable of things similar or more advanced to the ones us Humans are able to do now. It's also likely that they will start draining resources from Earth in a faster manner, and as a side effect *prevent other species, like mammals and primates, from evolving into Sentient/Intelligent dominant species*. In short, I'd say that the dominant species on earth would have been this Reptilian derivative, and not us, some Primate derivative. [Answer] Assuming that the dinosaurs survived, and somehow humans also evolved to what be what they are now, so dinosaurs exist alongside humans, humans would have hunted most of them to extinction, or at least submission. Humans don't do well at tolerating animals that threaten humans. Most dinosaurs that live in areas that humans want to live would be killed, domesticated, or driven off. There would still be dinosaurs in places that humans don't really want to live, such as jungles, savanas, wilderness, etc. which are the same places that the big predators live now. Things like lions, tigers, and bears live in these places mostly by leaving humans alone. Humans still go into those places to hunt the animals though, so they wouldn't be completely safe. ]
[Question] [ According to dungeons and dragons, Elves don't sleep, but go through a process called reverie. This is a meditative state in which they retain the restorative of sleeping, but they remain fully conscious throughout it. It is similar to REM state, where breathing and brainwaves slow down, and muscles relax. Elves are fully aware in this trancelike state, and must remain here for 4 hours. Not taking Revere for long periods of time will increase their disorientation and eventually send them into a coma. I want to give the humans of my world this ability while making them incapable of sleep. What brain or biological mechanism is needed to make this feasible ? [Answer] It is believed that meditation can be used to offset sleep in humans. The exchange ratio varies (30 minutes of meditation to replace 1 hour sleep is a common claim), so we're already on that way. The two parts of the brain I would focus on are the [Ascending reticular activation system](https://en.wikipedia.org/wiki/Reticular_formation#Ascending_reticular_activating_system) (ARAS) and the [Ventrolateral preoptic nucleus](https://en.wikipedia.org/wiki/Ventrolateral_preoptic_nucleus) (VLPO). The VLPO is responsible for managing the antagonistic relationship between neurons that encourage sleeping and neurons that encourage wakefulness, and the ARAS is responsible for actually carrying out the changes between waking and sleeping. Altering either of them has drastic effects on sleep. It would probably be "easier" to make the changes to VLPO to simply no longer have neurons that encourage sleeping. [Answer] Here's how brain waves differ; 1. Gamma State: (30 — 100Hz) This is the state of being hyperactive and actively learning. Gamma state is the best time to try and retain information. however too much of this will lead to anxiety and stress. 2. Beta State: (13 — 30Hz) our most common waking state, Beta State is associated with the alert mind state of the prefrontal cortex. This is a state of the “working” or "thinking mind" 3. Alpha State: (9 — 13Hz) We feel more calm and relaxed while in the “alpha state” after a yoga class, a walk etc. We are lucid, reflective, have a slightly diffused awareness. The hemispheres of the brain are more balanced (neural integration) 4. Theta State: (4 — 8Hz)this is the state where we can meditate at . it is categorised by the ability to visualise.It is also makes one feel somewhat drwosy with a higher capacity for intuition and problem solving. 5.Delta State: (1—3 Hz) Tibetan monks who have been meditating for decades can reach this in an alert, wakened phase. It is the same type of brain activity we all experience in dreams but they can do it while awake. So yes it is possible after much , much practice. some things that slightly less practice include things such as lucid dreaming. There was once a famous european violinist ( although his name escapes me) who they say used to practice in his dreams. Not to mention the great Indian mathematician Ramanujan who attributed most of his ( absolutely amazing!) work to his family goddess who he says came to him in his dreams and showed equations to him , often waking up with some radical idea that he would never bother to prove but that would be proven by others to be correct. So this too could be useful to you if the reason you want them to stay up is motivated by economy or desire to practice etc . [Answer] They are doing what [dolphins do](https://www.livescience.com/44822-how-do-dolphins-sleep.html), sleeping one half of their [brain at a time](https://www.scientificamerican.com/article/how-do-whales-and-dolphin/). dolphins who have to swim and breath of course cannot sleep the way we do, they will drown. Instead they sleep only one half of their brain at a time, maintaining low activity awareness the whole time. The process even takes 4 hours (2hrs per side) in dolphins. they are alert enough to spot predators, but they can't do much besides swim slowly, breath, and see until they wake up. Missing it too often is just like missing sleep for humans. Severe sleep deprivation in a normal humans leads to hallucination, coma, and death. [Answer] Nothing can substitute for sleep because sleep is not just resting. It's a physical state in which life-critical biological housekeeping gets done. The human body can't clean and repair its brain while the brain is in operating in conscious mode. If you want to make your humans do without sleep, then you just need to make up a reason, like they meditate and reconnect with the spirits of the ancestors, who then magically rejuvenate them or something. Or, you can just say they meditate, and your reader will probably forgive you if the story is a good read. Humans can't retain the benefits of sleep through meditation, because a critical function of sleep is to remove metabolic toxins from the brain. Meditation doesn't do that. The buildup of the metabolic toxins causes some of the effects of sleep deprivation and if enough toxins accumulate, they cause neuron damage and cell death. "The brain only has limited energy at its disposal and it appears that it must choose between two different functional states — awake and aware or asleep and cleaning up. You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time." [Source](https://articles.mercola.com/sites/articles/archive/2013/10/31/sleep-brain-detoxification.aspx) [Source](https://www.nih.gov/news-events/nih-research-matters/how-sleep-clears-brain) The brain also assists the body with healing during sleep by releasing hormones that promote healing, among other things. Lack of sleep has a host of bad health effects which would probably lead to an early death. "The physical healing of wounds is expedited by sleep, and sleep strengthens the immune system in general. Rats deprived of sleep in experiments show distinctly inferior healing capacities, develop skin lesions, lose body mass, and are unable to maintain a stable body temperature, ultimately dying of sepsis or just “exhaustion”. Sleep-deprived rats have been shown to exhibit substantially fewer leukocytes (white blood cells), the body’s main defence against infection, and sleep-deprived humans show less than half of the protective antibodies after an inoculation jab as compared to people with healthy sleep patterns." [Source](https://www.howsleepworks.com/why_restoration.html) [Source](https://www.bbc.com/news/health-24567412) If you want to know more, just do an internet search for the terms sleep brain metabolic clean and sleep allow body heal. [Answer] The idea of elf's daydreaming instead of sleeping comes from Tolkien originally. I would propose that this is not likely to be done on a the long term unless these humanoids have a great amount of neurons to sacrifice or a different regeneration method for neurons (wich in humans occurs rarely). Following that, if they had two minds associated with two different brains they could sleep and renew one while being conscious with another. The other brain could work as a hive mind so not to create a dissociative disorder in the person. The hive mind wouldn't be connected to any senses so it can go to sleep at a different time while the individual brain is awake. [Answer] **One of the items you want to incorporate is the release of Human Growth Hormone.** HGH is essential to making people thrive. The myth is it's only good for making children taller. The reality is that every one, of every age, needs it. It's how we rebuild muscle fibers after breaking them down through activity during the day. HGH also regulates insulin, breaks down toxins in the body, helps produce substances such as breastmilk, and does all sorts of other things. It is only released during sleep. If you've read about weight lifting how it's not the workout that builds your muscles, it's sleeping on it, this is why. Without HGH your muscles will slowly get weaker and you will have a lot more soft tissue pain (fibromyalgia, etc). Other body systems will start to break down. It won't kill you (not directly anyway) but it can really alter your functioning. A normal person can miss sleep now and then and be fine. But if you miss sleep for weeks or months, the HGH loss alone will really have an effect. ]
[Question] [ Time travel is a major staple is sci-fi. You just can't escape it. Sometimes the characters travel so far back, that if or when they tell locals that they are from the future, I'm skeptical that the story writers have the locals' reactions correct. I'm under the impression that the concept of time travel is relatively new. For example, would Socrates understand being told "I'm from the future"? What about George Washington? Maybe the answer is best found by finding who first talked about time travel. For the times before time travel was understood, how would you explain you're from the future, and not confuse that with some kind of declaration that you are a seer or prophet? [Answer] The first known instance of knowledge of the future being transported to the past (rather than a figure in the present seeing the future through clairvoiance) is likely the 1733 Memoirs of the Twentieth Century, which depicts a man receiving a series of memos written by an ambassador from the far future year of 1997-1998! These letters were given to him by an angel who did not discuss the method the angel recieved the memos from. Perhaps the most famous fictional example is that of the Charles Dickens Classic, "A Christmas Carol" (1843) in which Scrooge is transported to his early life and to his later life... or... well... no longer life. While these are supernatural, the first physical machine created and controlled by a man to traverse time was H.G. Well's "The Time Machine" (1895) Though there is a Spanish story that is about 12 years older. With all that said, the idea of a visitor from the future appearing in the past is not unheard of going far back, though if the locals find this idea to complex, one could try and tell them that you are seer blessed with the gift of future sight and have dressed in the manner of men in the coming ages? Then have someone say "like that story we had about the guy from 1997?" alluding to a oral traditional story that was lost to time... Though this seems to be a Dr. Who style gag more than anything. [Answer] **Anyone with experience of the past and the future will intuitively understand the *concept* of being 'from the future.'** The answer will be yes. We experience and understand 'yesterday, today, tomorrow.' We sometimes dream about being in another place or time. We experience deja-vu. The idea of psychic ability, clairvoyance, and so on, is deeply attractive to many of us. Many religions have certain 'impossible' tenets. Human cognition has no difficulty with the bizarre. Also, only a very small percentage of people in our *present* are familiar with time travel stories. Very few people think about time travel, being more concerned with other more basic facts of living. Yet these people would be able to understand the idea, we presume. Each of us who are familiar with the concept was introduced the idea at some **initial point,** and probably thought, 'Whoa. Cool." Not "Wait, what? I don't get it." (although perhaps the response is a mix of those two things.) **In point of fact, the ability to believe in what is not logical (such as time travel) is evolutionarily selected.** There is an entire field of study on pattern recognition, survivability, and illogic in humans. **If the science is to be believed, we'd not be here without the evolutionarily selected ability to accept (and believe that we understand) the impossible.** Examples abound. Belief in deities is alive and well, for example, and believers will tell you how they know this to be true. Our ancients were made of the same stuff as we are, and it stretches belief to think that they'd not have the same proclivities. [Here is one link on the evolution of ready acceptance of the improbable,](https://www.csicop.org/SI/show/belief_engine/default.asp) but a search in [Google Scholar](https://scholar.google.com) easily pulls up many, should that link cease to work. From the link: > > Our brains and nervous systems constitute a belief-generating machine, a system that evolved to assure not truth, logic, and reason, but survival. The belief engine has seven major components. > > > Now, it may well be that authors don't capture well the response of ancient peoples to a time traveller - but this is a writing problem. I suspect the ancient peoples themselves think about life in philosophical ways including how to escape place and time. Just as people today do... [Answer] Conceptually, they'd have no problem grasping the concept. After all, think of religions: "Do this/don't do this and you'll be punished/rewarded" depends on people understanding that doing things will have future consequences for them, which depends on understanding the concept that the future is a "real place" that will be experienced and have people there. If a place is real and has people there, that means, at least in theory, people from there can come here. And time travel isn't a recent concept. Assorted myths have people traveling forward in time, being taken to a place where time runs differently before being returned to the normal world. Traveling backwards is a more recent invention, but then thinking of time as cyclic, as many cultures did, simply means you've traveled long into the future to arrive in the past. [Answer] The tale of [Urashima Tarō](https://en.wikipedia.org/wiki/Urashima_Tar%C5%8D) could easily be the result of someone who has traveled at relativistic speeds such that he returns home 300 years later. That would be an example of someone who travels "to the future". "From the Future" would require a similar tale for the person to understand. ]
[Question] [ In a post-apocalyptic world, survival is often difficult. In the first few decades after the apocalypse, living in permanent settlements was dangerous because of roaming creatures and bandit gangs, which can wipe out an entire population in a single battle. So, some people chose to steal what they needed instead of making it. The Cobras, a raider gang, is one of the most powerful gangs in the former state of New York. For multiple generations, they have raided, pillaged plundered, and raped and were not completely against slavery and cannibalism. They are known as the most fearsome gang on the eastern seaboard. But after 500 years, most people in the wastes have at least partially rebuilt their societies. The really isn’t a scarcity of food, as people can make their own, and there aren’t as many bandits and roaming creatures as there were hundreds of years ago. So my question is, what might be a good motivation, if any, for the Cobras to remain nomadic raiders? [Answer] Because they can't. > > For multiple generations, they have raided, pillaged plundered, and raped and were not completely against slavery and cannibalism. > > > Why would any town or village let these people settle down? Townsfolk would get ready fight at the first sight of The Cobras, there would be no question of coexistence. And if The Cobras founded their own settlement they'd surely be attacked by every nearby polity. If nearby settlements weren't strong enough they would hire mercenaries, and they would ask for troops from other, stronger, towns and villages. And those other places would join the campaign against The Cobras because why wouldn't they? Why would anyone let bandits settle down and potentially grow even stronger? [Answer] So I fought ISIS and the Taliban in the middle east and its a bit similar of a situation. You see these guys and go "why would they choose a life like that? When hellfire missiles are falling like rain why wouldn't they just go home?" Its easy to say "oh it's just religion" but its actually a bit more similar to your raider's dilemma. The people we saw fighting in the Taliban or ISIS were typically younger males (teens to 20's) coming from utterly destitute backgrounds. I'm talking dirt floors mud huts and totally illiterate. So your terrorist (Raider) has a choice. He can slave away 14 hours a day on a farm, sleep in the dirt, and die at age 40 having earned nothing in his life except maybe enough to eat every day. Or...... He can run off and join these guys with guns. Once he's got an AK-47 he can have anything he wants. Women, money, drugs, property, cars, anything at all. He just has to take it away from anyone who gets in his way. Now he's not just a backwards illiterate dirt farmer, hes somebody with power and access to wealth. So then a bunch of guys like me show up and start wrecking it all, so why wouldn't he run away from it once the bombs start falling and angry Marines are blowing holes through the walls? Quite simply put he cant. He has been outcast by his family, clan and tribe and there is nowhere to go where his past wont catch up to him. No matter where he tries to run somebody will find out and an angry mob will string him up, and that's if he's lucky. If he's not they will take their time with him, set an example, and maybe work out some of the pent up grief and hatred they have after he and guys like him came through and took away everyone's daughters to be prostitutes, killed their sons, and took what little wealth they had. I've seen whats left when less developed societies decide to set an example. Its extremely unsettling. Its also paradoxical since such actions actually heavily dissuade anyone in the terror (raider) groups from deserting. Especially since when deserters are caught their own people will do the same to them as well. So I guess that gives you a reasonable motivation for why people would join such a group and why they wouldn't leave once it got tough or they started losing. [Answer] After 500 years there would still be plenty of motivation for malcontents, misfits and people banished from settlements to leave society and join the gang just as there is no shortage of gang members and affiliates in many countries today. Nothing extraordinary needs to happen, the extraordinary part is that a single gang endured for 500 years as an entity. There have been plenty in history but usually when they're big enough they establish their own kingdom on conquered territory and eventually have gang/raider issues of their own. Most of the Norse conquests were basically big raider gangs, the middle east and north India olden day kingdoms are basically all built from what were essentially the same thing. So for them to remain as a raider gang they would need constant losses to keep their numbers and power down, and constant recruits like outcasts banished from other places, outlaws basically. [Answer] Well, one thing that the Cobras could do to keep their lifestyle going is set up a protection racket which makes the raiding lifestyle safer and easier for everyone. They most likely protect their territory from rival groups already, so they can go to each settlement and trader, telling them that for protecting the area the people need to pay a tax. Pay the tax and everyone is happy, they don't pay, well... bad things will happen. Now, most people will pay because this large raider group could do a lot of damage even for the strongest settlement. Even if the walls and militia are too strong, the Cobras could attack every trader, traveler and work party that is out of sight of the walls. Paying the protection money, as long as the Cobras don't get too greedy, is safer for everyone. If a settlement is too poor to pay up in food, tools, supplies or horses/vehicles, they can pay with people. In fact, they'll probably demand some people from the weaker settlements. Depending on how the society works, the larger settlements might hand over criminals, debtors or malcontents to the Cobras so that they don't have to pay anything of real value. If these people show they're worthy they can join the gang officially, if not they stay slaves. A few people might volunteer to be tribute just for the chance to join up while sparing their community the tax. There may even be a few settlements that base their economy around the Cobras. The Cobras come in with their wealth and they can gamble, drink, sell and buy slaves, and whatever else they want as long as they pay. Not paying would make the townspeople repay the damage in kind while the Cobras in question are in a drunken and drugged up stupor. So long as the Cobras have the manpower, keep other raiders out, and don't act like wild dogs getting enough people to oppose them would be difficult. They would be the local gang that everyone grumbles about but everyone expects someone else to deal with. With that kind of racket, there is no reason for the Cobras to settle down. [Answer] # Mobile food source You never said that your Cobras get their food by farming. What if they don't? Three options: * The Cobras move in convoys to take advantage of seasonal crops in different areas. * The Cobras can keep their own livestock, and migrate around finding their livestock. * The Cobras don't make their own food, instead they steal from others. In this case, they move around to steal food from different groups as it becomes available. ]
[Question] [ Orcs and the like are often depicted with green skin, what kind of evolutionary pressures would lead to mammals with green, blue, etc. skin and/or hair? [Answer] There is a flaw in your reasoning here. You assume that there has to be an evolutionary advantage for something to happen. In many cases though so long as there isn't a disadvantage then something that does no harm can easily exist. For example human hair comes in a wide range of styles and colours because none of them has a significant advantage over any other so natural variance comes into play. So long as green skin is just as effective as some other colour (or maybe it's selected for because potential mates think it looks good in which case it just has to not be too much of a drawback) then it's just natural variance. [Answer] The green Orc is rather a product of dehumanization in the creation process rather than IRL settings. What I mean is that author think "hmm what I can do to make Orc appear not humans? I know, I give them reptile appearance so they will be perceived as cold and sleazy". But in magic/fantasy word the circumstances would be environmental. For example: when I was a kid I've had hair that were' almost white gold. Like straw. Because kids like to run and it's harder to spot bright point in field of wheat. When I grew older my hair turn tortoise. So I have patches of colors on my head. White, black and reddish/deep red. Because adult specimen should be easy to blend when hunting for prey. Also Orc can have certain color from their diet. Living in forest, eating roots give them green color. Living in mountains eating mountain thistle give them light blue/white color. [Answer] One reason for green skin can be skin cells' stability. As you already know, Sun's UV radiation can provoke skin cancer. This happens because high energy photons can tear away atom's outer electrons, turning them into ions with positive charge and increasing chances that regular biochemistry won't work as it should. Some molecules can be fragile to a degree, where the same effects can be produced by a mere green light. But then, if your skin contains a lot of green pigment, it means it reflects green light more than any other, thus protecting you. Blue and violet pigments will do the same job against the bands of spectrum with even greater energy. Another reason can be this - orc's skin contains chloroplasts and is capable of photosyntesis. Such feature should have appeared in their evolutionary line long time ago, presumably before their ancestors became multicellular. Maybe it was the preferred evolutionary line because photosyntesis in their environment gave much more energy than is possible with our Sun, so many species received those legacy genes. Yet another reason: this is mimicry. Orcs weren't always strong predators they are now (imagine goblins), so they had this adaptation to help them survive in their forests. Or even this: it's skin sickness, similar to melanomes produced by papilloma virus. Not quite destructive for the host, but everyone out there is infected. [Answer] Another possibility is that they are green because of something they eat. Like flamingos are pink because of what they eat: > > "The pink or reddish color of flamingos comes from carotenoids in > their diet of animal and plant plankton. These carotenoids are broken > down into pigments by liver enzymes." > > > [wikipedia entry](https://en.wikipedia.org/wiki/Flamingo#Feeding) [Answer] There could be something other than evolutionary going on. Besides the pink flamingo getting their coloring from their foods, things can become colored because of what they are exposed to. Sometimes referred to "smurf syndrome," argyria is a condition where a person has "excessive exposure to chemical compounds of the element silver, silver dust." > > <https://en.wikipedia.org/wiki/Argyria> > > > This causes their skin to turn purple, either in patches or in total. Like the flamingo, though, eating excessive amounts of vitamin C can cause a skin color change to yellow and even orange. It's extremely temporary, as vitamin C gets flushed from your system really quickly, and it damages kidneys and other organs. > > <https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/vitamin-c/faq-20058030> > > > It could also be an evolutionary change to using camouflage pigments/makeup to hide in the forest, so the skin picks up the pigments after constant use and the person/orc no longer needs to reapply. This (eventually) gets transferred to their decedents generating the green/brown/black coloring naturally. > > <https://i.pinimg.com/236x/7f/bd/1e/7fbd1e409ab324494dc453fcba2843f4--army-face-paint-katy-perry-videos.jpg> > > > ]
[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/78481/edit). Closed 2 years ago. [Improve this question](/posts/78481/edit) So one of the aspects of my science fiction world is genetic manipulation and modification of humans by one of the factions. I am wanting to have a subset of humans who receive a single eye transplant, or possibly both, for human eyeball sized mantis shrimp eyes to be used for combat. **Also I acknowledge that currently eye transplants are not even possibly yet**, but I assume that 200 years from now, the time of my story, that it will be possible to regenerate the optical nerves connecting the eyes and the brain. **Question 1:** Is it possible to receive an eye transplant from another animal at all, or would the differences in cells, DNA, ect cause a horrible reaction? **Question 2:** Assuming it was possible, would the eyes of the mantis shrimp, which see in 12-16 different spectrums, be able to be processed by the human brain? Would simpler eyes, like dogs which only see in blue and yellow, be able to be processed by the human brain? [Answer] There have been experiments with giving squirrel monkeys color vision through gene therapy, so that part may not be as far fetched as it sounds on the surface. <http://www.npr.org/templates/story/story.php?storyId=112897277> Xenotransplantation is also a thing, believe it or not. But it's really limited at this point. <https://en.m.wikipedia.org/wiki/Xenotransplantation> Xenotransplantation requires compatibly between species though. See the 'Potential animal organ donors' section of the wiki page above. I think that's going to be your biggest hurdle. Transplants between similar mammals are difficult, I suspect transplants between crustaceans and humans will be impossible. Things like blood type, size, and compatible function matter quite a bit. Blood type matching isn't possible in this case. The eye will require Hemocyanin, while the body uses hemoglobin. <https://en.m.wikipedia.org/wiki/Hemocyanin> [Answer] I tend to say **no**. It is **not possible** to have beneficial effect on having a mantis shrimp eye on human. Here is why: [Compound eye](https://en.wikipedia.org/wiki/Arthropod_eye) You might argue that you can connect the nerve to the brain, but our brain is not developed for compound eye. Our brain is not evolved to translate signals from hundreds of eyes. Even if the brain can adapt and translate the signals, it will not have significant **advantages** to normal-eyed humans, mainly because they are just not trained to use it, and the brain cannot use the full potential of the wonderful eye of the shrimp. It's different if you genetically engineered babies to develop with the compound eyes, as their brain will try to adapt to the eye signals. They will still have to adapt (read: evolve) through generations to develop proper brain region to take care of the signals. *However*, transplanting of non-compound eye might be feasible. Even if it is in addition to the available 2 eyes, brain can try to use the new eye, just like [the brain can adapt and use prosthetic limbs](http://www.dailymail.co.uk/sciencetech/article-3397823/Man-moves-robotic-arms-MIND-brain-controlled-prosthetic-attaches-implant-patient-s-bone.html). [Answer] There have been attempts at growing human organs on pigs, so you could go that way. However, I think that improved vision by genetic manipulation, or even fully artificial eyes are better approaches - easier, less handwavium - than pegging an overgrown multifaceted bug's eye into someone's face. [Answer] If your goal is to give a human the vision of a mantis shrimp, consider bionic eyes instead. These have been a thing since the 90's and [there are multiple ongoing projects as of now](https://en.wikipedia.org/wiki/Visual_prosthesis#Ongoing_projects). While this technology is still in its early days, 200 years from now you might be able to order custom made eyes with as many channels and filters as you like. You may even be able to customize the hardware and software yourself. This could make for far more formidable vision than that of any animal. [Answer] **Question 1:** No it's not possible to transplant an eye from an animal to a human, tissue rejection would be horribly swift & severe. Howsoever, with a little round or two of musical organs it's plausible, throw in some handwavium & it's definitely possible. Here's how, based in the main on ideas from [**this question**](https://biology.stackexchange.com/questions/79881/could-bone-marrow-transplants-help-make-xenotransplants-viable) of mine. Step **one**: grow a pig with a few of your cells & those of the donor animal of the organ you want (in your case an eye) introduced into the foetus in vitro shortly before it's immune system is calibrated. The pig will develop with an immune system that recognizes both your cells, the eye donors & its cells as its own. Step **two**: allow pig to grow to maturity. Step **three**: remove all of your own organs & tissues associated with your immune system. This won't be pleasant. Step **four**: replace with the pigs, this will kill the pig of course. You now have an immune system that recognises your own cells, those of the pig, & the eye donors as its own, no tissue rejection. Step **five**: transplant eye & job done, relax & have some bacon sandwiches from leftover pig. The big issue remaining is the severed nerve tissue you've spliced together, nerve tissue tends not to grow back. Accept that it does sometimes, there are people who have had arm transplants & the like who have gone on to regain use & functionality of their new arm & digits over time. So just throw in a little handwavium (you may need less than you might think here) & stem cells slathered liberally on the spliced nerves to promote growth, results won't be immediate of course. *Now for the big "But, this won't work", the tricks above should work well enough for xeno transplants from other mammals & perhaps even reptiles but something like a mantis shrimp that doesn't even use blood like ours is just much too different in its biology, individual cells wouldn't thrive transplanted as detailed (the cell chemistry is all wrong) so organs won't either.* *Think of it like putting a salt water fish in a fresh water pond, the environment (your body) is just wrong for it (a crustaceans organ) & it will die with or without an immune response.* *But stick to animals with the same blood & cell chemistry as our own & you'll be golden, plenty of mammals & such out there with eyes that do more or something different to ours.* **Question 2:** I have no idea, someone else will have to answer that, but I strongly suspect full functionality is unlikely for transplants to adult humans of eyes with differing properties to human eyes, though transplants to infants, the younger the better, will likely produce better results, not immediately but over time, as the developing brain is amazingly plastic. ]
[Question] [ I want to tell my kid an Atlantis-like story, where humans had the minimum required super powers to enable a group of people to create 1910s technology in a fairly quick and easy manner. I have a bit of a beef with "ancient alien astronaut" theorists, many of whom point at cool achievements of our ancestors, and (in a totally degrading way, I think) claim that the technologies required for achieving those are beyond humanity's ability to reach on our own. I say that we humans are pretty ingenious and can do quite a lot with very little. I truly believe that high-tech, or at least electricity-level civilizations, could have existed in the past, without aliens having to teach us how to change a light bulb. Still, in my story, I want to make it easy for groups of humans to get to a pretty neat level of technology without the hassle of a couple of hundred of years of industrial revolutions or Thomas-Edison-level geniuses. Looking at the requirements for, say, an electricity generator, would the ability of a group of people to purify metals be enough for the creation of the wires/turbines? Would I want to give my group a minor telekinesis ability to spin the turbines? Or just a heat generating ability to make steam? The key words here are "minimum" and "group" - I don't want super-individuals to fly around and lift giant rocks, using their hands to erect Stonehenge and the pyramids. Nor do I want them to kill each other in [Superman VS Hulk](http://marvelvsdccomiccrossover.wikia.com/wiki/Superman_Vs_Hulk/ "Superman VS Hulk") super-fights. What I need is a group of people, relying on each other, relying on technology, but capable of reaching a 1910s tech level quickly, starting from a nomadic/near-zero-technlogy point. * Groups = should have numerous humans, let's say 5 at the very least. * Near zero-technlogy point = Before metal forging and houses. They have tents, simple clothing and basic cutting tools. Prehistoric man stuff. * Reach tech fairly easily = Around 30 years (to give them time to figure out what they want to do and how to do it), starting from a nomadic/near-zero-technlogy point. * 1910s level of tech = Radios, cars (combustion engines), basic electrical devices (power generators). I specifically want transportation, communication, and power tech that my kid/others who'll read the story can relate to, and that will enable the building of monuments that 10000 years later people will say "oh, this was obviously a site of alien worship where people slaughtered goats to appease the star demons". (I say that Stonehenge was part of a larger structure for [drone racing](https://www.youtube.com/watch?v=fw6uzeeE9gc/). Who's gonna prove me wrong??) * The story takes place in the distant past, say 10000 years ago or more. * Later on in history there'll be a world-wide biological change that will disable the superpowers (explaining why we don't have them today, and why thousands of years passed without high-tech civs). It's not really part of the question but if your answer can take that into account, I'd be grateful. So my question is - **What type and level of super-power/s is/are the minimum required, in order for a group of people to quickly and easily create 1910s level technology, while maintaining each individual's reliance on the group, and on said technology?** **Edit1**: I see a lot of comments/answers telling me how limited my premise is, specifically the 30 year limit. Well, I could live with longer than 30 years but the point is that these guys have **superpowers**. While I try to go for the minimum of soft science, the question is about soft science. Got a problem with my timeframe? Tell me what superpower will solve that. Got a problem with the lack of knowledge of my civ? Think of the superpower, mental or physical, that will solve the problem. One guy wrote: "I think the basic premise is flawed, people don't make technological advances, societies do." And then he proceeded with: "So the only real answer is, [if] a person with time-travel/vision SAW the future" - That's one interesting way to solve the problem! Please keep an open mind and when you see the obvious problems, use your super-SE-WorldBuilding-power to suggest a solution. Cheers! [Answer] Note I consulted a number of answers to [What is the minimum size of a self-sufficient industrial country?](https://worldbuilding.stackexchange.com/q/6747/21704) when creating this answer. Also, be careful this post contains links to TV Tropes. ### People to maintain technology [This answer](https://worldbuilding.stackexchange.com/a/3296/21704) estimated that it would take between 10 million and 100 million people to maintain 2014 levels of technology. You will need less people since you are aiming for 1910 level of technology. However that is still an order of magnitude above a small group of people. So your group of people will need quite a few super powers to maintain that level of technology let alone develop to that point. ### 30 Year time constraint This is the biggest challenge to the question. Even if they had a guide book telling them what to do, it takes time and lots of it to collect the resources to build the machines that can process other resources to make the next generation of machines. So you will need a wide range of super powers that can help expedite this. ## 5 Superpowers needed for given time constraint: ### [Mad Scientist](http://tvtropes.org/pmwiki/pmwiki.php/Main/MadScientist) A family in this group should have a super power where they are not just super intelligent, but they are very good at applying it in ways to create crazy and amazing contraptions. They see the scientific process and scoff at it. They go directly to the solution to the problem (note sometimes the solution can be just as bad as the problem if not worse). They will help advance the technology as they think of progressively more advanced ideas and serve as the guide to technology. ### Item Duplicator Unlike those who have a super power of [self duplication](http://tvtropes.org/pmwiki/pmwiki.php/Main/SelfDuplication) this person can duplicate inanimate objects perfectly. Any item that they duplicate is indistinguishable from the original to the point the person performing it does not know which is the original. This is a very brokenly powerful superpower, but it is needed for the 30 year time frame. Once the group successfully makes a bar of iron, instead of wasting precious time mining and smelting more iron they can duplicate existing iron so they have a continuous supply of materials for industry. This power scales nicely, since as new materials are developed like plastics, alloys, and chemicals they can help make more of them rather easily. ### [Green Thumb](http://tvtropes.org/pmwiki/pmwiki.php/Main/GreenThumb) The person with item duplication can only duplicate inanimate objects, you need someone who can help accelerate materials that are grown. The role of this individual would be to grow trees, crops, and other plants. Wood is needed for a variety of construction, and different plants product different materials and chemicals that are used in various fields. For example growing crops so you can make bio-diesel to serve as your fuel. This will also let your group grow crops that are not indigenous to their location, which may be vital to their growth. ### [Teleportation](http://tvtropes.org/pmwiki/pmwiki.php/Main/Teleportation) and [Seer](http://tvtropes.org/pmwiki/pmwiki.php/Main/Seers) These people serves as your gofers. A small group will be isolated to one location on the planet. Unfortunately all the types of materials they will need to get to the 1910 technology level are likely not going to be conveniently located near their town. Therefore people are going to have to go find it and return with it. Seers could use their powers to help locate what they need while those with teleportation can quickly retrieve what the mad scientist needs for his or hers current project. ### Conclusion To reach your lofty goals you will need a lot of superpowers to do it. The ones listed above should serve as the minimum amount of superpowers needed to do it (even if it does seem like a lot). [Answer] # High intelligence Two things in particular bring forth technology: a need for it, and knowledge. A **need** is a thought; the idea that goes along the lines of "Hm... this could be done **better**". In other words you need someone that can imagine a better solution to a task or situation in their everyday life. Creativity is usually a "symptom" of high intelligence. **Knowledge** is obtained by examining how the real world to figure out how it works. Today we have formalized a process about this called "the scientific method". The scientific method is roughly this: 1. Observe reality 2. Try to find a pattern in how reality behaves 3. Make a hypothesis, and from various scenarios work out how reality **should** behave if the hypothesis is correct 4. Perform an experiment where you poke at reality, and record how reality reacts to this. 5. Compare the result of how reality behaved, compared to how you thought it would behave. If in point 5, reality and your hypothesis are not in agreement, start over from 1. If they do agree however, then you have just created a scientific theory, that is to say a reliable model of how reality behaves. Congratulations, you have made progress. The scientific method is not without pitfalls however, and it takes lots of foresight, introspection and after-action review to figure out where you might go / are going / went wrong. This too requires intelligence. So the super-power you need is **intelligence**. Do note... once they reach this level of technology, they will not stop. They will keep going, at a rapid pace. Mankind went from radio to semiconductors in less than fifty years. And then went from semiconductors to Facebook in the same amount of time. A caveat though: thirty years? That will not be enough. No matter how smart you make someone, there is only so much a group of people can do in thirty years. And going from rock bottom — literally so — to being able to build the RMS Titanic in thirty years, that will not happen. ...unless their superpower is to time-dilate the entire universe in order to give them more time for themselves. [Answer] There is an old saying: Necessity is the mother of invention. One of the problems with being from "the future" is many people have difficulty understanding that people from previous times don't know anything about current technology. They won't say to themselves "I need a light bulb, how do I invent one" They won't even have the concept of light bulbs; light comes from fire, right? Burn oil. Unless they need something they don't have they won't invent it. Unless they have free time to think about things they don't have, they won't invent anything. Might look into Hierarchy of Needs, basically you can't invent stuff until you have taken care of food, water, safety, sanitation, etc. Because all of your time is spent keeping yourself alive. The main reason people didn't invent stuff a long time ago was that they were too busy. Hand-waving all the basic needs away still doesn't get you new inventions. (e.g. you could have magic breadmakers, doctors and water purifiers) Why would they invent something if all their needs are met? I think the basic premise is flawed, people don't make technological advances, societies do. People make inventions, but only at the level they already are. (i.e. you don't jump from neolithic to steam overnight, or even a decade) And the only reason to advance is to fill a need. So the only real answer is, a person with time-travel/vision SAW the future, and returned to make some of the "cool toys" they saw. (Possibly bring some back) [Answer] The super powers you need are an understanding of the scientific method, and an abundance of food. The scientific method will help you understand everything that your brain is able to handle, and that is within your reach, so you get a chance of observing it. But that will not help you, if you have to spend 14-16 hours a day trying to get the next meal. Actually, not having the scientific method (although i hate to admit that) would be the lesser hindrance: you could still achieve enormous things by just messing around. But without food, all you could possibly achieve is a grave. Other superpowers might still speed that up, granted. Telepathy comes to mind: if you can share your insights with your peers a lot faster than before, you can have your ideas peer-reviewed in no time, allowing for a quicker route to the next iteration. And allowing for the next man climbing onto the shoulders of a giant faster. Then again, you could already get a long way by just having the superpower of literacy among your group. Again, this is only helpful if somebody is providing food, shelter, and wherever possible an infinite supply of the most expensive laboratory equipment you can think of. [Answer] What if the humans are nothing special but there are *animals* that are notable? For example, birds build nests. Perhaps you have a jackdaw that likes finding shiny nuggets of this magnetic stuff that sticks together well for its nest. You have a burrowing worm that excretes the gold wires that it cannot digest. Things like that. By making it the animals that are special, you remove any need for the humans to interact with each other in some special way. And the reason the powers go away is easy -- humans screw up the environment and the special animals die off. There is ample evidence in the archeological record that when humans first moved into an area, it didn't take long for the major fauna to die off and the ecology to be disrupted. I think for the tech you're looking for, you mostly need raw materials, which is why the animals I first suggested are both examples of that. Steam is easy -- water and fire. What is harder is good steel. There's a theory that Babbage's Difference Engine would have worked if the Brits of his time had been able to manufacture cogs of sufficient precision. If we have some animals that can help with that -- say, a special mollusk shell that provides a perfect mold for circles -- then you can bootstrap all sorts of industry. [Answer] In one sense only 1 super power is required. A SciFi book "Time is the simplest thing" - Clifford D. Simak, first published in 1961. The story combines paranormal abilities, Telepathy and Teleportation (not essential to your question). This is not a story review or synopsis. A man makes contact with an alien intelligence that is alone and searches the Galaxy for life with its mind. Once it finds a suitable life form, it “trades” minds. Meaning it copies everything the lifeform know and gives it everything it has picked up over it’s …. Very long life. Now to your story, we have a group member that makes contact, is given the knowledge and nothing more, no help, no anything. Let me make this absolutely 100% clear, this individual is NOT GIVEN THE POWER TO DO EVERYTHING. To say this a different way. The GROUP IS 100% REQUIRED TO SOLVE THE HOW TO AND THE IMPLEMENTATION. IF human A sees human B doing activity X then human A figures it out ... that is ALL that is being done here. To meet the requirement, I made human B an alien, i could have been a whale, a porpoise, a squid, an octopus a bird (you want me to point you to Daedalus?). The individual can pull up anything and make the connection but this does not give understanding, how to or anything else. Recontact with the Alien is either declined or ends with a “sorry I can not help you”. Spin this however you want, One individual knows something can be done, following a sequence of steps, which one could say is 90% of the discovery. Think how many things we use but do not really understand how it works. It also allows you to end the spontaneous evolution of knowledge when the person dies. Or if you want you can have the individual write things down but a lot is lost in translation what they see to what what is available to the group allowing for a ramp down of the burst of invention, the further the descendants are from the original group transitioning the written work to mythology, kust a good story etc. ]
[Question] [ As far as we know stars have a limited fusion cycle. Once they fuse elements up to the element iron, there is no subsequent energy that can be released through fusion, given the inherent atomic structure of the element iron. So premise aside, my thought experiment is: if advanced beings were able to magically 'program' or 'augment' a star through some unfathomably advanced technology to skip the element iron and continue fusion, and assuming our current understanding of chemistry/physics still holds water in this scenario, what properties would the star have? Would the ability to fuse heavier elements imply a meaningfully longer stellar life span? Would that imply that more stars would be massive enough to create super novas? Would that increase the upper threshold for heavier elements the star could create if it goes super nova? Would there be a possibility for new elements? That is the basic question, although we could continue down this continuum and have the super smart beings account not only for iron, but any element that would interfere with fusion. Thanks for reading. [Answer] No. Look at a graph of binding energy and it makes an arch, with iron at the top. **All** elements higher than iron will consume energy to produce, not release it. [![Graph](https://i.stack.imgur.com/mSwKP.gif)](http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.html#c2) (From *hyperphysics*) --- Ideas to look into in order to get more energy from a white dwarf than its residual heat is providing (they take billions of years to cool down to a black dwarf): * strange matter. [Strangelets](https://en.wikipedia.org/wiki/Strangelet) *might* be more stable than normal atomic nuclei under the pressure found inside a white dwarf. Catylizing the production of *strange* atoms could be a literal answer in the spirit of the question posed. * gravity. Start collapsing the material into a black hole. This can release close to the entire rest mass in energy, and is *far more* than you got with fusion. Charles Stross called this a *necro star*. [Answer] That is a slick graph JDlugosz posted. I am intrigued to see that the binding energy is on the way back down. Since their tech is "unfathomably advanced" you could propose that they have hopped all the way up to the high atomic weight "island of stability" where they can start getting a return on their fusion. <https://en.wikipedia.org/wiki/Island_of_stability> That trend line should cross back into the yield area by 300. Plus the prospect of stable superheavy elements is cool. ]
[Question] [ Say you were to implement in the cranium, a series of baffles (similar to the system used in an airplane, to prevent the fuel from sloshing around). And arrange them in such a way as to partition the skull, and subsequently the brain inside, in a number of smaller spaces (separated by relatively rigid membranes). Thereby reducing the overall potential inertial energy available in the contained "fluid" in this case the brain... so that if ever the head is subjected to blunt force trauma, the "sloshing effect" would be greatly reduced if not cancelled completely. [![enter image description here](https://i.stack.imgur.com/kT2j8.jpg)](https://i.stack.imgur.com/kT2j8.jpg) ^ an image ^ of the inside of a fuel tank showcasing a series of perforated baffles designed to reduce the movement "sloshing" of the fuel. Assuming that the separation does not sever synapses (rendering you brain damaged), and being done with some sort of nano-technology, or some such. **Would it be possible, or at least plausible, that this could work?** The purpose of this question is to discover a method that can prevent concussion, brain bruising... liquefying... or at least theorize a plausible futuristic method. I mean, if I was Wolverine and had this anti-concussion stuff, then I could be shot in the head with a bazooka. And assuming the rocket wasn't tipped with Adamantium, then I wouldn't be fazed, and my brain would be chill as a cucumber :D [Answer] A mechanical solution would not solve the problem of tissue damage caused by steep acceleration gradients without actually addressing the mechanism of tissue damage directly. The baffles solutions solves the fuel sloshing problem by dispersing the momentum of a fluid onto a solid plate, and it mostly does that so that the fuel pump intake or level measurement doesn't become uncovered unexpectedly. Also, at eight pounds a gallon, if you let that slosh at full speed on a dead stop, the tank itself has to be a lot more robust to not buckle under the dynamic forces. Even if the brain could have survived having the baffles installed, which is unlikely, the baffle would only serve to become the thing causing the tissue damage. Worse, if the acceleration was applied along the direction the baffle was oriented, it would cause a very high cutting force to be applied to the edge of the baffle. The key problem is that brains are complex, and human brains are more complex than many other kinds. It abstracts to an electrical signaling network, but it does that with complicated chemical interactions and ion exchange. Ultimately the problem you're trying to solve comes down to protecting the paths supplying oxygen and nutrients, and preventing the signal paths from being interrupted. Helmets work by providing a space in which the head can float a bit, pushing around a cushion. Accelerating the helmet also accelerates the head, but any steep changes hopefully get rounded out by the padding. An internal solution would either have to mimic that, or simply make the brain more durable somehow. One solution is to backup frequently and rewrite after an incident; this is used in the setting of the webcomic *Schlock Mercenary*. An alternative is to simply avoid the problem by other efforts using remote access, á la *Ghost in the Shell* or *Surrogates*. [Answer] Could it work? Possibly, but its not a good solution: Lets say that you separated brain into smaller parts, each one responsible for different area. If I hit you hard enough in to brain part that is responsible for, lets say, vision, I would still cause a concussion and possibly damage your vision. True, I wouldn't damage parts of the brain that sit in other compartments, but I'd still do damage. Also if I'd damage one brain part, its quite possible it would start sending wrong information to other brain parts causing gods-know what effects on your body. Here lies another problem: if you want to separate brain parts leaving only small gaps between them you will greatly reduce the transmission speed between those parts. Conclusion: Nature likes simple solutions: look at animals that fight with their heads, i.e. bulls or even better this guy called Pachycephalosaurus: [![Gives "Thick-headed complete new meaning](https://i.stack.imgur.com/PD9Mu.jpg)](https://i.stack.imgur.com/PD9Mu.jpg) Instead of having complex brain compartments they have thicker skulls that absorb the impact and reduce the damage. [Answer] [Project Graham](https://www.boredpanda.com/graham-body-survive-car-crash-road-safety-victorian-government-patricia-piccinini/?utm_source=google&utm_medium=organic&utm_campaign=organic) is a crash test dummy designed by a sculptor and trauma surgeon to show what a human designed to withstand a car crash could look like. Some parts of the design are flawed but several underlying ideas are applicable. To prevent concussions, Graham has a larger skull and neck-brace like structure which stops his skull from experiencing as much acceleration. And his brain is attached more securely within the skull by multiple ligaments. To enhance a regular human to be more resistant to concussion you have to take similar steps. Make the skull more dense, increase neck muscle, strengthen the connective tissue of the neck, and then attach the brain more securely to the inside of the skull. [UIDAlexD](https://worldbuilding.stackexchange.com/users/23527/uidalexd) had an interesting idea about improving brain cushioning by anchoring the brain to the skull with a lattice of carbon nanotubes. A combination of HGH and anabolic steroids could be effective in improving skull density and muscle mass. HGH can thicken bones and support the muscle growth caused by the steroids. Another option would be to use gene therapy to increase [muscle mass](https://pubmed.ncbi.nlm.nih.gov/12559968/) and [bone density](https://pubmed.ncbi.nlm.nih.gov/26150503/). And connective tissue can be replaced with stronger [synthetic versions](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4444979/). [Answer] There's two problems with concussions. First is the simple mass of the brain. If I crack my head into a wall, the front of my brain is going to impact my skull. However, since the brain is fairly squishy, the back of my brain is going to keep moving forward, compacting the gray matter inbetween and damaging it. When it rebounds from said compression it will then impact on the back of my skull, causing further damage. Second, is that the human skull isn't smooth inside. There's all kinds of nasty sharp edges that can actually lacerate your brain tissue if you hit your head. [![enter image description here](https://i.stack.imgur.com/nUbwp.jpg)](https://i.stack.imgur.com/nUbwp.jpg) **So, the solution is twofold:** First, figure out how to more securely anchor the brain. The most extreme and far fetched idea I have is to weave a lattice of carbon nanotubes through the skull to cradle and dampen the motion of individual neurons. The brain is then much less elastic in a collision, and won't slosh to and fro. Second, is to smooth out the inside of the skull. This would be some pretty extreme surgery, but remotely possible with modern technology. By doing this you'd reduce the trauma the brain experiences when being lacerated by your own skull. [Answer] Yes (to an extent)! due to the square-cube law. To simplify, i will be treating the brain as a cube. This assumption is of course wrong but it will nonetheless demonstrate my point. The problem with accelerating the brain quickly is the large force (and thus pressure ) required to do so, if we imagine the brain as a 1400 g cube of water (a reasonable assumption) then 20G of acceleration along one of the faces causes a force of 275 neutrons on one of this cubes roughly 121 cm^2 face. This is a pressure of about 20 KPA or 0.2 atm (which seems to small, despite the fact i've double checked my math.) anyway, if you then split your cube into eight smaller cubes each cube will have half the volume relative to the surface area, and thus half the mass to accelerate. Thus the force (and pressure) on the back face on each of theese smaller brain cubes is halved! the more you divide your brain up the smaller these forces will get. It's the same reason that shorter towers are stronger. That being said you need to make your supports out of something VERY strong, probably titanium since it's light strong and biologically inert. You could try drilling small holes in your titanium to feed synapses through but i doubt that'll work for many reasons (you'd need to reroute synapses, perform brain-surgery more precise than any in human history and you'd weaken your titanium). I'd advise using "smart titanium" that can operate as a synapse instead (though obviously not perfectly otherwise you'd just build an entire brain out of it.) A good rule of thumb is that your resistance to G-force increases by the factor of the number of divisions you have along the axis the G-force is experienced on. This system should also work with ANY of your internal organs, (provided your titanium boundries don't prevent them from functioning of course. The titanium boundaries should also serve to reflect shock-waves to some extent as the moved through regions of varing density. Though obviously this doesn't protect the regions OUTSIDE the boundaries. That being said i'm not overly experienced in the mechanics of shock-waves so won't give a definitive answer in that area. [Answer] I think it's not possible to implement, because it would most likely be illegal and not necessary. First of all, open violence between civilian population such as duels have been outlawed a long time ago. So why would you reinforce the skull? What's the goal here? Secondly, that would be a major surgery. Or heavy genetic engineering. You would need a very libertarian government to get away with doing such kinds of body modification. ]
[Question] [ As part of a series on plant animals, plantimals if you will, I am now asking about ears. All surface life has them or some sort of equivalent to them and with good reason. Other than sight, hearing is the most crucial sense. But what about plants? While it has been [documented](http://abcnews.go.com/GMA/story?id=1165678) that plants can hear, that was over a long period of time with the effect being only growth. The blueprints are there, but not the bar. How would a plantimals' ear work? What would it look like? How could it come in being? Next Question [Digestive System](https://worldbuilding.stackexchange.com/questions/68542/what-is-the-botanic-equivalent-to-the-digestive-system) Previous Questions [Heart](https://worldbuilding.stackexchange.com/questions/59818/what-is-the-botanic-equivalent-to-the-circulatory-system) [Muscles](https://worldbuilding.stackexchange.com/questions/59194/what-is-the-botanic-equivalent-to-muscles) [Eyes](https://worldbuilding.stackexchange.com/questions/64859/what-is-the-botanic-equivelent-to-eyes) [Answer] ## Trichomes Perhaps plants could begin to hear via their hair ([trichomes](https://en.wikipedia.org/wiki/Trichome)) in the same way [jumping spiders do](http://www.livescience.com/56496-jumping-spiders-sense-far-away-sounds.html): > > Researchers found that the spiders could also sense and respond to sounds coming from distances more than 9.8 feet (3 meters) away — no small feat for a creature that measures just 0.04 to 0.98 inches (1 to 25 millimeters) and lacks ears and eardrums. > > > "Instead of eardrums that respond to pressure, spiders have these extraordinarily sensitive hairs that respond to the actual movement of air particles around them," Shamble told Live Science. "Though they differ in size and number, these specialized 'hearing' hairs are found across virtually all spider species." > > > [Answer] "Although it has not been proved, the suspicion is that plants can perceive sound through proteins that respond to pressure found within their cell membranes. Sound waves cause their leaves to vibrate ever so slightly, causing the plant to respond accordingly." Source: [The Washington Post, *Can plants hear? In a study, vibrations prompt some to boost their defenses*, July 6, 2014](https://www.washingtonpost.com/national/health-science/can-plants-hear-study-finds-that-vibrations-prompt-some-to-boost-their-defenses/2014/07/06/8b2455ca-02e8-11e4-8fd0-3a663dfa68ac_story.html) Plants need to be able to hear insects eating them to they can raise their defenses, so plants are already primed for the evolution of what we might call "ears." All that needs to happen is for these pressure-sensitive cells to cluster together. Then, it would make sense that a structure would form to better gather sound, which would be the exterior portion of the ear. In plants, this part would probably resemble a folded leaf, like a wolf's ear. Depending on the type of plant, the ear might be tightly rolled or loosely cupped. It might be smooth-rimmed like a lily leaf or jagged like an oak leaf. If your plantimals can move away from danger, that would prompt the evolution of better ears than simple plants have. To a plant, the best it can do with the knowledge that something is coming to eat it is to make itself taste bad. While that's better than nothing, it's not exactly a sure-fire protection. If the plant could actually *move* away from the predator it would have much better chances of surviving, so a plant that could hear the predator coming before it was already there would have a major advantage. I don't know exactly what "plant animals" means, but I would say that if you intend your plants to resemble animals, give them two swivel ears of leaves that resemble those of the base plant. If your plantimals are going to look like plants, set the ears close to the stem, probably in the crook of a branch. [Answer] You could probably have something similar to sonar. Many animals can locate underground prey with vibrations in the ground. There is a chance you would just have to make something up here though. ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 7 years ago. [Improve this question](/posts/64402/edit) I'm writing a tragedy in which my main character runs away using a giant balloon. Just as he realizes his folly, and decides it's time to return from whence he came, the balloon pops. I want him to die. Could the shockwave from a balloon popping kill little Timmy? [Answer] **Forget it, your deadly shockwave by simple popping is not going to happen**. Balloons must be lighter than air which means either hot air or helium/hydrogen. Hot air does not use closed balloons, else you could not heat the air (While it is possible to build a closed system, it is senseless. It only adds weight and complicates the system). Neither helium nor hydrogen are used under pressure at sea level (!) because it only worsens the buoyancy and both gases are extremely volatile and diffuse through nearly every material. Higher pressures only worsens the diffusion. When hydrogen/helium balloons are rising, the gas is expanding because of the lower pressure until the balloon pops at a specific height. As consolation I will tell how you can kill little Timmy. You have the following options: * **Asphyxiation**. If the balloon goes up, from 4000-6000 m little Timmy will get unconscious because the air is too thin. From 7000 m on (death zone) humans will sooner or later die, the sooner the higher the ballon is. Both helium and hydrogen are able to reach stratospheric heights (10 000 - 30 000 m). * **Explosion**. Use contaminated hydrogen with air or oxygen which is the explosive oxyhydrogen. Let Timmy use an open flame or let the ballon rise through a cumulonimbus cloud (thunderstorm) and let lightning hit the balloon. * **Fall**. Let him fall down because he is too stupid, he wants to commit suicide, the ballon loses air or is in flames (Hydrogen fire which is not explosive has almost no feelable thermal radiation, it won't burn you if you are not very near the flames. Helium does not burn). You can also let burst the balloon like weather balloons, the trouble is that it happen in a height where Timmy is already dead (first point). * **Freeze to death**. Use a cumulonimbus cloud and let Timmy ride up and down with the down- and updrafts in heights where he can still breathe (something like 6000 m should suffice). In this heights the temperature has cozy -40 °C/F (yes, it is the temperature which is in both scales identical). Your choice. ]
[Question] [ Assuming that during the middle ages on Earth, all wind stopped. Some magic spell has made it so that air will no longer move faster than a gentle breeze from thermodynamics (the speed air moves out of the way of a solid object is unchanged). What would the be the consequences of this? [Answer] ## Short Answer: Everyone would die ## Long Answer I don't think there would be many dramatic instant effects. Some children (and adults) would have their kites drop from the sky, stuff would stop blowing around, sailing ships would be stuck and the temperature of some room would increase or decrease slightly. After some time the last wave would hit shore leaving the sea pretty much still, tornadoes and hurricanes would stop. After a few days the problem arrives. Without wind systems warm, moist air won't move around. Water might still evaporate but it won't travel meaning anywhere away from a large body of water will dry up. Lakes might be alright as the evaporating water will fall back into them and the sea will be fine but anywhere else will get very dry very quickly. Plants, animals and humans will slowly die from dehydration with most water inaccessible as salt water or ice. Even if we survive this the problems don't stop. The equator will no longer shed its heat as quickly so it will become very warm, mountains may remain cool enough to be habitable but nowhere else will. At the same time the poles, deprived of heat from the equator, will freeze solid. There are other effects but it basically boils down to everyone dying. [Answer] at least two effects. Air pressure would start increasing drastically anywhere warm. To the point that walking from a sunny spot into shade would involve explosive decompression. the poles would freeze solid. [Answer] Temperature extremes would increase, probably threatening life near the equator and the poles. Travel by sail would disappear -- and any oceanic sailors far from land when this happened would be in real trouble! Fire would act differently, without convective air currents to move the heat, bring in more O2; probably not able to spread as fast, but hotter and more asphyxiating where it does burn. Perhaps only small fires are safe/usable while this spell is in place. [Answer] General situation would be "as if" air viscosity would be much higher. This means air would still travel for shorter distances (at the maximum 1mph speed), so a (relatively) narrow strip near the sea would still be habitable. Coasts relying on breeze would have very narrow (<<10Mi) strips, while geographic winds like Monsoon could penetrate much farther. It would be interesting to see if the energy is dissipated by viscosity (converted to heat) or kept as kinetic (air becomes more heavy and thus the slow moving air would still push as if a molasses wave). That depends, of course, on specifics of the "spell". ]
[Question] [ I have a native tribe in pre-Columbus America that has successfully domesticated small, omnivorous bears. They are similar in size to Sun Bears [120–150 cm (47–59 in) / 27–80 kg (60–176 lb)]. I want to use the bear as dog replacement but I don't think its plausible to use them as hounds or to make them herd. Is there any useful thing that my domestic bear could do well for the tribe beside being a pet? I'm not looking for [bear cavalry](https://worldbuilding.stackexchange.com/questions/38502/would-a-bear-cavalry-be-feasible), just anything useful where a bear fits better than dogs & cats. The bear is domesticated not tamed,tribe successfully breed it for generations as pets. Please no suggestions for the bear as food source. Edit Just watched documentary about Sun Bears , the good thing is that even Tigers who share habitat with Sun Bears won't [predate](https://youtu.be/HXb8zrpZaYE?t=9m34s) them, the bad news is that humans in Indonesia keep them in cages and cut their paws one by one as [delicacy](https://youtu.be/HXb8zrpZaYE?t=3m6s) :( [Answer] > > Brown bears can be found in many habitats, from the fringes of deserts to high mountain forests and ice fields. In Europe, the brown bear is mostly found in mountain woodlands, in Siberia it occurs primarily in forests while in North America they prefer tundra, alpine meadows and coastlines. The species' main requirements are areas with dense cover in which they can shelter by day. [Link to source](http://wwf.panda.org/about_our_earth/species/profiles/mammals/brown_bear2/brownbear_ecology_habitat/) > > > Most bears, like the browns above don't thrive in rainforest-type environs, but there are some like the [Speckled Bear](https://en.wikipedia.org/wiki/Spectacled_bear) that do. Note that smaller bears tend to use trees more. Most bears are fairly solitary, however, they will be seen near each other when food is more abundant. I believe that if they are domesticated and fed regularly, you can train them out of the more solitary behavior. I would say a hunter could make use of two of them very efficiently. Ideas for use * If they are trainable, and there is agriculture, you could get them to focus on eating bugs to help with crops. They should only be trained to eat fruit that they are given. As kingledion suggested in his answer, they can also be encouraged to kill/ drive out other animals. The fact that they are smaller might mean that they are more agile and can be used this way. * Use them for hunting game, as you would [a catch dog.](http://www.huntwildpig.com/the-1-best-hog-dogs-to-hunt-wild-boar/) Again they should only be trained to take a certain amount or just food from the trainer. * As trackers. There is actually some evidence out there that bears can and [do track food sources and people](http://www.foxnews.com/science/2014/11/24/gps-study-tracks-grizzlies-as-follow-hunters.html)...in some cases, very, very patiently. * Although they are not protective of places, they are protective of cubs. If that can be transferred to a specific person, they might make good body guards, if they are awake. Bad ideas * Using bears to guard a geographical area. Most bears are not naturally territorial, so unlike a dog, they make very poor guards. This is despite [good hearing, decent vision, and sense of smell](http://www.bearsmart.com/about-bears/general-characteristics/). They just don't alert to much. * Making them into a herd. Bears can be social, but they don't group up naturally and I believe that conflicts will arise if you force this. Having them stay with their trainers and know each other seems feasible, but keeping a standard herd of them seems like a bad idea, given what there is about their natural behavior. [Answer] Dogs were probably hunting partners at first, and eventually guarded things and provided companionship. A bear could do all these things well. Cats were used for rodent control. A bear could not do that well. Other domesticated animals were primarily for food. A bear may seem non-optimal for that, but it depends on the environment. # Bear Herding If your civilization is in a rainforest, a sun bear is actually one of the best mammal options to herd for a nomadic lifestyle. They eat insects, palm shoots, and fallen fruit. Sure you could never get vast herds of them, but smallish herds of edible bears (or milking bears?) would be practical given some human engineering of the landscape. Specifically, if humans cut down non-fruit bearing trees, there would be a.) a lot more sunlight on fruit bearing trees, and therefore more fruit, b.) a lot more fallen logs full of insects and c.) plenty of firewood. Also, it would be worthwhile to kill all the monkeys you could find to leave more fruit for the bears. You could then move your herd of 50 bears around feeding them on fruit and bugs. [Answer] # **Finding Food** Bears have excellent smell and hearing. Use them in a hunter-gatherer society to find fruit plants, honey, catch fish in the river, find and hunt small game etc. A single bear accompanying a small group of human gatherers would be invaluable. [Answer] Assuming you actually managed to get to tame the bear. I am also assuming small brown bear as sun bear is not very useful for anything. Similar to dogs bears are excellent fighters. Even though your bear is quite small, it still can do damage. Additionally, bears are excellent hunters and scavengers. They can scurry food for their master. They run quite fast. So at the end of the day, they are dogs 2.0 [Answer] Bears are nice and fury and soft. They can be slept with for warmth and comfort, not unlike a teddy bear. Australian Aboriginals would sleep with dogs for warmth. They might also be territorial like a "den mother" and attack intruders to protect the tribe. [Answer] If you assume black bears made it into South America (or else relocate your society to the southern United States) then they might be the best choice for bear domestication . They're not particularly aggressive compared to other species but are large enough to do useful work - in particular as pack animals i.e. as replacements for donkeys and mules. Since horses were absent in the Amercias prior to the arrival of Europeans in effect they could be low altitude substitutes for llamas and perform similar roles. (With enough selective breeding who knows you might even be able to harvest bear fur for weaving.) They're also very intelligent and trainable animals so if raised in groups and trained properly you might be able to yoke them together in teams for plowing, stump pulling and other haulage duties. ]
[Question] [ Hermaproditism (simultaneous and sequential) and cyclical sex-swapping would seem to eliminate patrilineal and matrilineal concepts of inheritance and allegiance, but I really want one of my alien societies built around the model of great families/clans and major/minor houses. Inheritance to the eldest offspring or designated heir is easy enough, but without the classic human division of male and female sexes how might it be determined whether an individual is marrying "into" one family and not the other way? Family/house standing can change over time, so relative position probably shouldn't be grounds for deciding and wouldn't help if two families of equal standing are involved. Being the eldest/heir could mean your spouse(s) marries into your family, but what if two heirs are to marry? And what if you, a non-heir, marry "out" of your family and your older sibling (or the designated heir) dies, are you suddenly back "in" your family and your spouse(s) "out" of theirs? ## Question So, how could a hermaphroditic or sex-swapping species produce a society of inter-, extra- and parafamilial alliances and rivalries (i.e. clans, greater and lesser houses, extended kinship) through marriage or some other foundational mechanism?   --- **Background:** This is set in a hard*ish* sci-fi universe in which Earth-typical sexual dimorphism and unchanging sexual characteristics are atypical. There are multiple intelligent alien species. While *Game of Thrones/ASOIAF* would seem to be the inspiration for the society here, I'm actually drawing from *The Kindly Ones* by Melissa Scott. [Answer] First, this kind of setup doesn't *have to* eliminate patrilineal and matrilineal inheritances or tracking - there might easily be a distinction between children sired or borne by an individual, and priority given to one over the other as far as inheritance goes (I suspect it would be priority given to heirs born of the body, since that *feels* like a closer link, even if genetics are nearly the same). A family that has all the children borne by one parent, will be following that parent's clan, a family that has both are just going to have the kids be mirror-claimed by each parent. Also, if children borne by a person follow their house or clan, and children sired follow their partner's - it might not matter too much which person is marrying into/out of their respective families, since both with maintain their individual standing, and which standing the family as a whole tends to claim will probably depend on both what the relative houses standings are, and what status each individual has in their respective houses. Possibly with the option of going independent or unclaimed, to form a minor household at the very bottom of the social ladder, for those outlying cases where a claim is absolutely unwanted by whoever is deciding. It would probably be best, I think, either for individual families to choose which claim has priority in a given pairing, or else for the clans or houses to decide between them which one has authority over the pairing. Maybe historically or in conservative clans, the clan has the right to decide if they will claim a pair (and being clan-less or unclaimed is a punishment, exile), and in modern times or liberal clans, the pair decides which clan they will follow (being clan-less is then a protest)? The issues that may come up if a family wants to, or wants not to change allegiance because of relative standing, or of a clan would like to exert or remove a claim (perhaps needing a new heir, or other political shenanigans), are then potential plot elements - especially if changing the primary claim *after the fact* takes the agreements of everyone involved, or at least two of the three. Note - this last bit of complicated setup can hold true even if you don't have the sired/borne division of inheritance, it will make for messy familial politics if clans or pairs have to negotiate their claims and the possibility of refusing, or renouncing claims exists, but again - that gives *plot-points*. Birth order may play a role in deciding which clan a pair wishes to claim, or relative standing. The choice for a pair to claim as primary the status of heir to a lesser house or minor player in a greater is an honest question, and of course heir can be based on birth order, or not - it can add an extra layer of intrigue the heirs are favored or handpicked by the previous head in a major house (or if each house has their own mechanisms for determining what makes a potential heir, or protocols for what may happen if the head dies without having chosen). What will also play a major role is the individual characteristics of the clans, houses, families, and pairs - staying in a minor house which is friendly or open vs a major house which is backbiting and aggressive in status games is, again, an honest question. Individual occupations may play a role, as the clans may specialize, or value, certain occupations more than others - so a pair or clan may well place a higher value on the claim that more closely matches their interests. [Answer] If there is any logic of social dominance within a married couple, regardless of the lack of sex/gender, then most concepts of a traditional gender-oriented society could be adapted. There are infinite possibilities, for example... ## Age The entire culture could be built upon the principle that *age is power* including within a marriage. So the oldest of the couple would always be the "dominant". When two individuals marry, the younger leaves its family to join the older's. ## Social Class The society is stratified in distinct classes or castes with a linear hierarchy (e.g. nobles > knights and priests > craftsmen and entertainers > peasants) and marriages within one class are forbidden. Social rank defines rights, property and sucession within a couple - so the lowest rank individual leaves its family to join the higher rank one's. Offspring would be assigned to a class at birth or at least before reaching adult age (many possible methods: a) choice by priest, b) first child inherits higher parent's class, other ones inherit lower parent's, c) trials, d) lottery etc.). Once defined, social class is final. ## Combat Ability In a very warlike culture/species, the wedding ceremony could involve ritualistic non-lethal combat. The winner would be the dominant partner for the length of relationship. [Answer] It had never actually occurred to me that deciding which family you are joining was a reason for gender-specific inheritance in the first place, and I'm not sure it's historically and cross-culturally true even in us non-hermaphrodites. Primogeniture just means "inheritance of the first-born", with stipulations around gender an addition which varies across cultures in time and place. Primogeniture is really not about marrying "into" or "out of" families: it's not the status of the spouse that matters, but the status of the *children*. In short, what titles and privileges do they stand to inherit, which their parents inherited in turn? Let's say Al, the first-born child of house Li, marries Bo, a lesser child of house Ka. Li inherits a major Duchy, whereas Bo is given a minor title and a few estates. Their only child, Cho, stands to inherit both claims, but clearly the Duchy will be their most important inheritance. It might be that, due to the disgrace of house Li, Cho decides to style themselves as the first of a new dynasty: the first Ka Duke. Or, for political expedience, they might try to forge a new house of Li-Ka, encouraging their cousins to intermarry and unite the houses. If Cho marries Dee, of house Mu, who also inherits a duchy, things look different again: their first child, Eed, will inherit both titles; the minor titles might be distributed to other children. The new united Duchy will either become a powerful united force, under the Li-Mu, or Ka-Mu dynasty, or it will fragment, with rival claimants on either side plotting to wrest one or the other title from Eed and their descendants. Any number of combinations are possible, and European history is full of wars fought because of them, and there's no need for gender to play a role at all. [Answer] This may be a great opportunity for you to revisit existing dynamics regarding families. For instance, maybe marrying heirs is how families signify that they want to merge. Or married couples form their own "pod" that has different rules until some ritual let them integrate a family (this could be born out of the need for exogamic behaviors in a species that can produce as many females as it wants). Or this species could have developed genealogy into a science and wouldn't look at families the same way we do: different groupings would be relevant for different occasions (economy, war, art, religion, etc.). Maybe they could have evolved senses to perceive how they relate to one another (pheromones?) or developed complex fashions to signify ancestry. This world provides many interesting storytelling ideas. [Answer] I think your problem does not need to be a problem. All these "undecided" things could move your story along because they give rise to social conflict. In medieval Europe, the heir was well-defined. That did not stop younger brothers or even sisters from trying to get their own. And families with only daughters would have a son-in-law, or even an uncle, inherit. All this led to a lot of scheming and GameOfThrones-like antics. So I suppose you could go with some simple method to decide on the heir for a house (for example the "Age" answer that dnep gave). A couple where neither partner inherits would just need to start their own house (probably of low standing, and they may need to make up a new family name because their older siblings do not want to be associated with a much lower house). This gives room for a lot of maneuvering/politics among siblings (either subtle or violent), competition for "good" partners (which leads to a certain sexual culture: either very free or very restricted), etc etc. What will your marriage laws be like? I remember Orson Scott Card's "Homecoming" series where marriages need to be renewed or dissolved every once in a while. Or maybe you're using arranged marriages as a plot device. Will this lead to population control laws? Or certain forms of birth control? Or will couples be able to determine the future of their children to a much greater extent than humans. For example, it might be legal to banish/disinherit/kill your child if they commit a certain transgression. My advice: think carefully of ways to climb the social ladder, possible religious influences, and the marriage / birth control practices in this culture. ]
[Question] [ So I am looking to structure a country so that there are other areas that are "free" to make their own laws but pay a tribute to the main country. I know that there's historical precedent (Rome's a good example). I am trying to get an idea of the practical advantages and disadvantages to allowing mostly local laws to hold sway over the outlying bits of an empire/country (consider that it is geographically continuous, although there are mountainous bits and Southern Isles). [Answer] It all depends on the technology available, as always. This text is being written without sources, and should be considered a mildly-educated opinion. (i studied sociology, but only as a second field, and i didn't have the best grades). For this answer, i shall call the primary country the "country" and it's parts "states". ## Decentralization - the good Giving your "states" freedom allows them to accomodate better to their individual requirements. A country-wide law banning a certain fertilizer might not harm state A, but state B has a harsher climate, and absolutely requires this fertilizer to grow anything. It also allows for better fit of culture and law. Maybe your country has several tribes / people / cultures living togehter, and giving the states more freedom allows upholding their traditions better. Imagine a country with 50% muslims and 50% christians, but state A has mostly muslims and state B has mostly christians. By allowing each state to set individual holidays, both cultures can uphold their religious holidays and both are happy. A country wide law could declare both, either or neither of these dates holidays, resulting in the industry, either or both factions being unhappy. So, another BIG BIG point is happyness. allowing regional laws, administration etc... makes the people happier. Because of above reasons, but also because they feel are more in control, the "way up to the power" is shorter. Finally, if your states consist of conquered territory, giving them more freedom makes the feeling of "being conquered, and now shamefully working as slaves to a foreign ruler" a bit less painful. ## Decentralization - the bad Decentralization has several disadvantages, too. For one, the country lacks control over what the state does. A state pushes it's own hedonistic, anarchic, selfish culture as the only way of life, creating unrest und dispute between the states? Bad luck. Also, the same freedom that keeps the people in the states happy can cause them to become unhappy, too. State A has 41 holidays, you pay 12% tax less than everywhere else, you don't need to go to military sercive and they pay you 1000 credits if you move there? That's nice, but is that gonna make the people in state B happy? Probably not. So people might start immigrating, moving, and the country faces the problem that it's own states are "fighting" among each other. Also, you have a harder time establishing a "sense of nation". If the states work very independend from each other, and state A is attacked - state B might not feel compelled to send help, and even if they do, the soldiers might not feel like defending their home country, but more like "helping the neighbour". People might feel proud to be a citizen of state A, not the country. This might lead to problems with loyalty, especially when recruiting members for country-service, since their loyalty to a state within the country might make them corrupt or at least biased in their interests. Sometimes it is necessary for a country, that all states "pull one rope", e.g. to establish a common space station or some similarly expensive project. Independent states might be hesistant to go for it, or use their powers to force the country to drop their project, for example by blocking other projects where possible. ## Decentralization - the ug... erm, the reasons So far we found arguments for and against decentralizing your government. But in some cases, decentralization becomes a requirement, not a choice. And that is when your country becomes larger than technology allows. When the fastest means of communications is a man on a horse, certain "response times" become too long. Asking for permission to fight an invading force? Okay, wait 6 months until we can grant it. Economic crisis requiring immediate reaction? Well, 2 months until the courier reaches us, 1 month to decide, 2 months to send someone back, who then gets lost, 4 more month until you notified us, then we send another.. ah, nevermind, damage is done. Sometimes, reacting to immediate demands requires a government right on the location. Of course you can limit their powers, but granting them more powers makes the government much more effective. Everytime i send a message, it costs time and thereby directly and indirectly money. The fewer messages i have to send, the cheaper the system becomes. A local government can react faster and more approprietly. For them, gathering additional information is much easier, they might know the local situation, special circumstances and even some or most of the people they govern. A central government might make decision based on insufficient information, and might deem it too time consuming or expensive to gather more information. They also have to factor in that 100 less-than-optimum decisions might still cost the country less than sending messengers all over the place. With advancing technology, a proper mail system and ultimately long-distance communications, centralizing a government becomes the better choice, because you do not need to employ so many people to do the same job, and ironically, the time until a decision is made DEcreases for a properly centralized government. You can gather information as required, and still have the "big picture" in mind when deciding. A local government might have the local picture and can decide best whats good for the STATE, but they cannot possibly have a good picture of whats up in other states or the country overall. So with proper communications, centralization is much more effective. Advancing further through technological advancements, with introduction of interstellar space flight, decentralization might again become the instrument of choice, as the distances between stars make communication harder again... until you discover FTL communications... and so on... [Answer] * Conquered people may be more willing to accept a new overlord if they can keep their own laws. Who cares if the Duke has to pay homage to the new Emperor and not to the old King if life goes on as always? * You can also "finesse" the degree of fealty of outer provinces. Say the king of some distant island sends tribute every year, and the emperor sends a subsidy for the local naval squadron. By custom, those two payments balance. Everybody gets to keep face. * Local laws may be designed to solve local problems in an equitable way. If drought is a problem, the law will spell out how water from a creek gets divided. If flooding is a problem, the law will spell out who has to maintain protective levees. A law that tries to do both will be confusing. [Answer] The real reason for allowing other areas to be free is that they are too far away to control. In a pre-modern world, without efficient communication, the only real advantage of conquering a place was carrying off all the loot. So once the place stays conquered, all you really want is more loot to make it back to the capital. This is how Rome ran its provinces, and the great eastern empires like the Ottomans and Mughals too. Local people have their own infidel customs, and while it would be nice to stamp those customs out with an iron boot, that takes a lot of effort, and they are far away, so just looting as much money is good enough. There simply were no centrally unified nations in the modern sense, until Spain, France and England in the 1500s. As we have moved to the modern world, the State is getting better and better at micro-managing what happens in the provinces. First the rise of the European nation state lead to public education that stamped one language on the population. Then transportation improvements brought the disparate parts of nations together, and allowed representatives from the provinces to go the capital, as well as bureaucrats from the capital to go the provinces. Finally, instantaneous media like TV and internet forge a sense of a national commons. Instead of waiting days to hear about Congresses decisions in the newspaper, now you can watch what they do on CSPAN or get up to the second updates from SCOTUSBlog. The result is, in the modern world, there is very little devolution to the provinces. Even here in America, which has a constitutionally mandated federal system, the states have only the faintest glimmer of independence from the national government. 25-50% of state budgets come straight from the feds. States can't really make their own unique laws and ways of life. District of Columbia wants to ban guns? [Hammered](https://en.wikipedia.org/wiki/District_of_Columbia_v._Heller) by the Supreme Court. Charlotte wants to be gay friendly? Overruled by the state of North Carolina, which in turn is probably about to get hammered by the Supreme Court, as well. So I argue that there aren't disadvantages or advantages. The state always exerts the maximum amount of control it can get away with given the state of technology. [Answer] # Imperial Expansion (by conquest or otherwise) While there are some laws that a new imperial power will want to apply across all territories, most regions will have complete and comprehensive legal systems already in place. As a general rule, there's no need to interfere with these systems and it will aid integration not to do so. There's also the religious aspect, if they all have the same state religion then they probably all have very similar legal codes, which gives you even less reason to interfere. You don't need to go in, conquer a new territory, and tell them murder and theft are bad, you only really need to tell them what their new taxes are. There's no real downside to this, it saves a massive amount of bureaucracy and effort when expanding. In the long term it may be worth centralising but it's not strictly necessary unless something is way off your norms. While you may have to periodically impose from above, you'd do that by sending a prefect to deal with the problems and find a local solution, rather than sitting on your golden throne a thousand miles away, with out of date information, trying to solve the problem remotely. *The short version of this is that there's actually no reason to bring a new territory under a centralised legal system unless there's a massive cultural disconnect between the legal systems, and even then you'll want to do it gently.* # Current examples **Byelaws** [Wikipedia](https://en.wikipedia.org/wiki/Byelaws_in_the_United_Kingdom) > > In the United Kingdom, byelaws are laws of local or limited application made by local councils or other bodies, using powers granted by an Act of Parliament, and so are a form of delegated legislation. Some byelaws are made by private companies or charities that exercise public or semi-public functions, such as airport operators, water companies or the National Trust. > > > Mostly these tend to consist of alcohol free zones and parking regulations, but the principle is there. There are many factors that apply only at a local level. **Local laws** There are also local laws from earlier days that even recently hadn't yet come off the books. As an example, Both Hereford and Chester had trouble with the Welsh. So [local laws apply](http://news.bbc.co.uk/1/hi/wales/6204511.stm) > > you can shoot a Welsh person all day on a Sunday, with a longbow in the Cathedral Close, Hereford. > > > There, an ancient law says Welsh people can be shot with a bow and arrow inside the city walls and after midnight. > > > *I don't suggest using either of these as a defence in court.* ]
[Question] [ In my world, Southern Europe, Northern Africa and all the territories surrounding the Mediterranean belong to a single empire. The Emperor and his Council have decided that they are going to [drain the entire Mediterranean Sea](https://worldbuilding.stackexchange.com/q/55673/18252). They have of course read about the century-old [Atlantropa](https://en.wikipedia.org/wiki/Atlantropa) plan, but they are going to do it with (real-world) 2016 technology. They are a mighty empire and are willing to make this a massive project with a humongous amount of resources allocated to it. They are willing to spend decades if need be. The motive for doing this is to gain more land-area. [![enter image description here](https://i.stack.imgur.com/5xuhX.png)](https://i.stack.imgur.com/5xuhX.png) They're planning to build a dam across the strait of Gibraltar to hold back the Atlantic. The empire also controls all land around the Black Sea. They don't mind draining it. But if it presents big challenges, they may also consider simply building a second dam to hold the Black Sea back. 1. Is the Gibraltar dam feasible? 2. Will the Black Sea dam be needed? 3. Are any other dams needed to separate the Mediterranean from other oceans? 4. Are there any other significant challenges that might make it impossible to hold the Mediterranean separate from the world's oceans? (Serious challenges also solved are a bonus.) No elements of fantasy or hand-waving are allowed. This needs to be explained in a scientifically sound way. Do also note, however, that there are little or no *political* problems. The Emperor and his Council do control the entire region, and have no *political* problems with the plan. It's an extremely prosperous and resourceful empire, and there is no lack of political or public will. Please note that while this is indeed *similar* to Atlantropa, it is not *identical* to Atlantropa. For example, the Empire intends to drain the whole Mediterranean, not just parts. [Answer] **Is the Gibraltar dam feasible?** The Strait of Gibraltar is 14.3km across and up to 900m deep. The highest dam in the world is Jinping-I at 305m. The largest by volume (of the dam itself) is Syncrude Tailings Dam in Canada at 88m high and 18.2km long. For reference Three Gorges is 2.3km long and 181m high, and is the 21st largest dam in the world by volume The structural problem with the Strait of Gibraltar dam is its height. No other dam in the world is even close. I don't think any armchair material science/math is worth doing to support the science based tag, but I strongly doubt that ANYONE has done a rigorous structural engineering evaluation of a poured concrete structure that could handle this kind of pressure. Thus the remaining option is simply an earth-filled dam. If we assume, for safety, that we want to make the dam 10km long along the strait (in addition to 15km wide across the strait, and up to 1km tall (to account for the depth). I will assume the depth profile is a simple 'V' (300m depth at the edges, 900m in the middle) with a 600m depth average, then the total volume of fill is 90 cubic km. 90 cubic km of rock weights 240 billion tons, at 2.65 g/m$^3$. Assuming the average rock has to move at least 100km from where it is dug (the Saharan Atlas would be a good source of rock) up to the Strait, that would take 24000 billion km-tons of freight rail, which is more than double the 10000 km-tons of freight rail moved annually, worldwide. The US produced 2 billion tons of construction aggregate (I couldn't find a world figure) and the world produced 3.2 billion tons of iron ore, so the amount of material that has to be mined is probably an order of magnitude higher than the total annual mining production on the planet. While I can't say all those numbers mean the dam isn't feasible, I would at least say that creating the dam is a decades long project, considering that the investment in mining equipment and rail transport will probably cost as much as if not more than the actual construction of the dam. Keep in mind, if you want to actually use the dam for hydro-electric power and not just as a big earthen ocean-stopper, you will need ALOT more concrete. Since total world production of cement is 1.7 cubic km a year, you may have to invest in a lot of concrete production, which in turns means investing a lots of power to drive that very energy intensive process. **Will the Black Sea dam be needed?** The Black sea is good for fishing and helps moderate the local weather. I would not empty if it I didn't have to. If you are already spending trillions/decades on a Gibralter dam, you can probably afford a Bosporus dam as well. **Are any other dams needed to separate the Mediterranean from other oceans?** I don't know if the Suez canal exists in your world, but that would need to be stopped up too. **Are there any other significant challenges that might make it impossible to hold the Mediterranean separate from the world's oceans?** A thought to consider: what would the climate be like in the newly exposed region of the Mediterranean basin? [Here](https://en.wikipedia.org/wiki/Messinian_salinity_crisis#Relationship_to_climate) are some possibilities. The basin would be in a location with little inflowing moisture. The Sahara desert is to the south, Northern Europe isn't actually that wet and any moisture from there is blocked by mountain systems (Pyrenees, Alps, Dinaric Alps, Balkans, Taurus, etc). It would probably be very dry. It would also probably be very hot since it is so deep below sea level. The Dead Sea is at the same latitude, and is the only comparably deep place on earth. It is not called the Fertile Sea. The Mediterranean sea is the source of the winter rainfall in North Africa, Italy, the Balkans and Turkey. The massive summer evaporation drives rainfall in the high mountains surrounding the sea, in turn powering the rivers. If you remove the sea, you remove the rain. The whole region turns into one huge continental desert surrounded be mountains. Compare to the [Tarim basin](https://en.wikipedia.org/wiki/Tarim_Basin) in China. Why would this civilization go forward with this project to turn their Empire into an arid wasteland? Who wants more land area if it is like that, and comes at the cost of reducing the rainfall in the already productive parts of the empire? And why remove the wonderful internal lake (Mare Nostrum?) that provides everything from fish to beach holidays to cheap water transport? Building this dam would be suicidal. [Answer] The short answer is "of course"; given the investment of sufficient time and resources. Atlantropa was well thought out and entirely plausible given the technology of the era. Alantropa's series of dams across Gibraltar and the entrance to the Black sea are sufficient in of themselves. The real issues are not so much getting a dam built, but the issue of allowing access of shipping to and from the Atlantic and to and from the Red Sea. So part of the plan will have to be modified to provide a series of locks in the Atlantic dam and to extend the Suez canal into the shrunken Mediterranean sea and provide a series of locks as well. Of course another channel and locks will be needed for the Black Sea as well. Sadly I was unable to find an estimate of how much material would be needed to build the dams for the Alantropa project (and including the mid Mediterranean dam linking Sicily to Africa and Europe). The calculations that were done between the 1930's and 1950's seem to indicate that it would take 35 years using the technology of the day. Building the same project using today's technology might not actually be any faster, since much of the time would be digging, mining and transporting materials to build the project, and some of the bottlenecks would not be breakable with current technology (for example the railroad tunnels and bridges might not be capable of being enlarged or "doubled" to handle the increased volume of traffic). Other bottlenecks could include how many trained workers can be diverted from other areas of the economy, and how much investment capital can be diverted from other investments. While the political authorities may be capable of diverting any amount of capital and labour to the project, the market has various ways of responding to distortions like that, including inflation or deflation, price swings and other follow on effects. These are not quantifiable without much more detailed information, but there certainly will be effects on transportation, the construction trades, mining and quarrying and energy, both during the period when the project is absorbing these inputs, and later when the project is complete and the huge capacities created to support the project become surplus or idle. So one of the biggest issues for the Empire in this timeline isn't the physical project itself, but dealing with the second and third order effects caused by the mobilization of capital and labour to build the project. [Answer] An earthen dam is the way to go. As far as moving the earth, here's the key to the whole thing: **Don't handle it dry**. All the dam materials get handled as a slurry. No endless parade of trains and trucks, just pumps running 24x7. The thickness of the dam is limited only by your patience. I am a huge fan of making dams much, much thicker than the engineers say they need to be. Watching the torrent of water do absolutely nothing, "Dear God, what were we thinking, why did we make the dam so thick" was said by no one, ever. Now if you have the time, before you seal it off, you gate it for one-way flow. Let the stream of water from freshwater rivers keep the Med full but slowly reducing its salinity, like the Baltic. Meanwhile you may want to think about a system of canals along the south edge of Europe connecting the river outlets, Bosphorus and Nile to their ultimate outlet, the Suez Canal. This preserves navigation from the Atlantic to the Danube, Odessa and the Arabian Sea. Again, you are much better off placing the materials *before* you drain the Med. ]
[Question] [ On Earth, life took on a quadruped body plan which has lead to many different sub body plans; 4 legged, 2 legs-2 wings, 2 legs-2 arms, etc. This has made me wonder what possible sub body plans can exist on hexapods. Ignoring tails, what are the possible ways a hexapods limbs can be arranged? [Answer] **Wings**, I suppose, only work in pairs, so they must be an even number (and imply bilateral symmetry): 2, 4, or 6, or, of course, none. **Legs** seem to be necessarily more than one, or none. **Arms** could be any number, from 0 to 6, though 5 would be weird, as wings need to be in even numbers, and legs need to be more than one. **Fins** could be in any number, but their relation to symmetry is interesting; I suppose they could be radially distributed in a perpendicular plan to an otherwise bilateral organism. So, ignoring other possible - or impossible, but interesting - kinds of members... * 6 wings disposed in three pairs - weird creature that only flies. I doubt this could be a predator, unless it has a bucal apparatus like those of ants. * 4 wings and two legs - bilateral creature with as many legs as a bird, and as many wings as an insect. * 2 wings and 4 legs - Pegasus! * 4 wings and 2 arms - they must fly to move, or crawl on their arms. But then are their arms really arms? * 2 wings and 4 arms - same as above. Somehow, I feel that with time two of these arms would evolve into legs unless they live in places with extremely irregular relief. * 4 wings and 2 fins - similar to some flying fish? * 2 wings and 4 fins - another kind of flying acquatic animal. * 6 legs - could have either a radial or a bilateral distribution (like a wingless insect, *Lepisma* for instance). * 5 legs and 1 arm - like a starfish with an arm at its centre... * 4 legs and 2 arms - Centauri! * 3 legs and 3 arms - another radial monster. * 2 legs and 4 arms - I think some creatures in the movie *Men in Black* are like this. Also, similar to some Hindu gods, though with less arms. * 6 arms - a fixed animal, perhaps, like some sea anemones with hands at the end of their tentacles. Or maybe like an octopus with two tentacles less - but are they still arms if their primary use is locomotion? * 5 arms and 1 fin - a radial creature, probably a seagoing predator. * 4 arms and 2 fins - like a dolphin with arms? Or mermaids with extra arms? * 3 arms and 3 fins - a quite weird radial critter. * 2 arms and 4 fins - Mermaids? Fins could be distributed either bilaterally or radially. * 1 arm and 5 fins - perhaps like an anglerfish with an actual arm instead of an illicium? * 6 fins - very much like a dolphin with two extra fins. Or could be like some creatures in Escher etchings, also with two more fins. * 2 wings, 2 legs, 2 arms - Angels, for instance. * 2 wings, 3 legs, 1 arm - a small change, and they don't like angels at all anymore. * 2 wings, 3 legs, 1 fin - not sure that such critter would be able to either fly, walk, or swim. * 2 wings, 2 legs, 2 fins - winged tadpoles? * 4 wings, 1 arm, 1 fin - again, not sure this could function. * 4 legs, 1 arm, 1 fin - like a starfish with an arm and a fin, and a leg less? * 2 legs, 2 arms, 2 fins - Mermaids with legs? * 2 legs, 3 arms, 1 fin - another monster I have trouble visualising. * 3 legs, 2 arms, 1 fin - I shouldn't be writing this at night, it might give me nightmares. * 3 legs, 1 arm, 2 fins - and this is hardly better... I can only hope they don't have mouths like those of lampreys. and finally, * 2 wings, 2 legs, 1 arm, 1 fin - I wonder what environment would have produced this kind of thing. Semi-submersed forests, perhaps? [Answer] The number of paired-limb [bilaterally symmetric] plans for hexapods will depend upon how many types of limbs one allows for; radially symmetric plans require a single limb type (otherwise, they would necessarily not be radially symmetric). Given that we're considering hexapods' hypothetical configurations, a trilateral symmetry would probably be in keeping as well. If we assume only the constraints of your example set of {leg, wing, arm}, then the resulting possible combinations are: * 3 [radially symmetric](https://en.wikipedia.org/wiki/Symmetry_in_biology#Radial_symmetry) configurations -- legs x6, arms x6 [I would presume tentacles, here], wings x6; * 7 unique-counts of [bilaterally symmetric](https://en.wikipedia.org/wiki/Symmetry_in_biology#Bilateral_symmetry) [**combinations**](https://en.wikipedia.org/wiki/Combination) (not including the radially symmetric configurations, which technically qualify as any higher order of body symmetry) -- short-handed here as {a, l, w} for brevity yields {lla, llw, aal, aaw, wwa, wwl, alw}; * 24 [**permutations**](https://en.wikipedia.org/wiki/Permutation) possible, of the above-named *combinations* -- {arms, legs, wings} short-handed here as {a, l, w} for brevity yields {aal, aaw, all, ala, alw, awa, awl, aww, laa, lal, law, lla, llw, lwa, lwl, lww, waa, wal, waw, wll, wla, wlw, wwa, wwl}, which gives us 18 sets of two-same/one-different and 6 sets of three-different-pairs; * 3 [trilaterally symmetric](https://en.wikipedia.org/wiki/Rotational_symmetry#n-fold_rotational_symmetry) configurations, wherein the hexapods have triplets of limbs (rather than pairs), would yield alternating pairs of opposites {alalal, awawaw, lwlwlw}, not including a pair of triplets being equivalent to a bilaterally symmetric configuration (e.g.: lllwww). [Answer] Two on each axis around a sphere. One on each face of a cube. Rather than different *function* but arranged in a line, they are facing or working in different *directions*. [Answer] The configurations that come to mind are: 1. 2 each for the various functions - locomotion (legs), dexterity (hands/arms), flight (wings). 2. Radial - like a six side start fish. 3. 3 legs, (like a tripod) and 3 arms/hands. 4. Modification of #1: 2 each for the various functions - locomotion (legs), dexterity (hands/arms), 2 for grosser function like lifting heavy weights. Hope that's helpful. [Answer] Assuming that these aliens are more-or-less like vertebrates, then there are around 150 combinations: * arm, arm, leg: A 4-armed humanoid * arm, arm, fin: A 4-armed creature like a swimming crab * arm, arm, prehensile foot: A 4-armed ape-like creature * arm, arm, prehensile fin: A 6-armed creature like a swimming crab * arm, arm, flipper-leg: A 4-armed mermaid-like creature * arm, leg, leg: A centaur * arm, leg, prehensile foot: An ape-like centaur * arm, leg, flipper-leg: A mermaid-like centaur * arm, wing, leg: A winged humanoid * arm, wing, fin: A flying creature like a swimming crab * arm, wing, prehensile foot: A winged ape-like creature * arm, wing, prehensile fin: An aquiline creature like a swimming crab * arm, wing, flipper-leg: A winged mermaid-like creature * arm, fin, fin: A mermaid * arm, fin, flipper-leg: A mermaid with legs * arm, prehensile foot, prehensile foot: Another ape-like centaur * arm, prehensile foot, flipper-leg: An ape-like aquatic centaur * arm, prehensile wing, leg: A 4-armed winged humanoid * arm, prehensile wing, fin: A 4-armed winged creature like a swimming crab * arm, prehensile wing, prehensile foot: Another winged ape-like creature * arm, prehensile wing, prehensile fin: A 6-armed flying creature like a swimming crab * arm, prehensile wing, flipper-leg: An amphibous winged humanoid * arm, prehensile fin, prehensile fin: A sea-turtle centaur * arm, wing-leg, leg: A bat centaur * arm, wing-leg, prehensile foot: An ape-bat centaur * arm, wing-leg, flipper-leg: An amphibious bat-centaur * arm, flipper-leg, flipper-leg: Another sea-turtle centaur * arm, flipper-wing, fin: A flying sea-turtle centaur * arm, flipper-wing, flipper-leg: Another amphibious bat-centaur * leg, leg, leg: An insectoid * leg, leg, prehensile foot: An eagle-footed insectoid * leg, leg, flipper-leg: An amphibious insectoid * leg, wing, leg: A dragon * leg, wing, prehensile foot: An eagle-footed dragon * leg, wing, flipper-leg: An amphibious dragon * leg, fin, flipper-leg: A sea-dragon * leg, wing-leg, leg: A more realistic dragon * leg, wing-leg, prehensile foot: A realistic eagle-footed dragon * leg, wing-leg, flipper-leg: A realistic amphibious dragon * leg, flipper-leg, flipper-leg: Another amphibious insectoid * leg, flipper-wing, flipper-leg: Another amphibious dragon * wing, leg, leg: An avian quadruped * wing, leg, prehensile foot: An aquiline quadruped * wing, leg, flipper-leg: An amphibious avian quadruped * wing, wing, leg: A 4-winged avian creature * wing, wing, fin: A fully aquatic 4-winged duck-like creature * wing, wing, prehensile foot: A 4-winged aquiline creature * wing, wing, prehensile fin: A 4-winged aquiline duck-like creature * wing, wing, wing-leg: A 6-winged tetrapteryx * wing, wing, flipper-leg: An amphibious 4-winged avian creature * wing, wing, flipper-wing: A duck-like tetrapteryx * wing, fin, fin: A fully-aquatic duck-like quadruped * wing, fin, prehensile fin: A fully-aquatic aquiline duck-like quadruped * wing, fin, flipper-leg: A duck-like humanoid * wing, wing-leg, wing-leg: A 6-winged avian quadruped * wing, wing-leg, flipper-leg: A 4-winged amphibious avian quadruped * wing, flipper-leg, flipper-leg: A duck-like quadruped * wing, flipper-wing, flipper-wing: A flying fish * fin, fin, fin: A 6-finned fish * fin, fin, prehensile fin: An aquiline 6-finned fish * fin, fin, flipper-leg: A 6-finned humanoid fish * fin, flipper-leg, flipper-leg: An avian quadrupedal fish * fin, flipper-wing, fin: Another flying fish * fin, flipper-wing, prehensile fin: An aquiline flying fish * fin, flipper-wing, flipper-leg: A winged humanoid fish * prehensile foot, leg, leg: An onocentaur * prehensile foot, leg, prehensile foot: An ape-like onocentaur * prehensile foot, leg, flipper-leg: An amphibious onocentaur * prehensile foot, wing, leg: Another dragon * prehensile foot, wing, prehensile foot: An ape-like dragon * prehensile foot, wing, flipper-leg: Another amphibious dragon * prehensile foot, fin, flipper-leg: Another sea-dragon * prehensile foot, prehensile foot, leg: A hexapedal ape-like creature * prehensile foot, prehensile foot, prehensile foot: Another hexapedal ape-like creature * prehensile foot, prehensile foot, flipper-leg: An amphibious ape-like creature * prehensile foot, prehensile wing, leg: A 4-armed dragon * prehensile foot, prehensile wing, prehensile foot: A 6-armed dragon * prehensile foot, prehensile wing, flipper-leg: A 4-armed amphibious dragon * prehensile foot, wing-leg, leg: Another more realistic dragon * prehensile foot, wing-leg, prehensile foot: An ape-like realistic dragon * prehensile foot, wing-leg, flipper-leg: An amphibious realistic dragon * prehensile foot, flipper-leg, flipper-leg: A sea-turtle onocentaur * prehensile foot, flipper-wing, flipper-leg: A flying sea-turtle onocentaur * prehensile wing, arm, leg: Another 4-armed winged humanoid * prehensile wing, arm, fin: A 4-armed winged creature like a swimming crab * prehensile wing, arm, prehensile foot: A 4-armed winged ape-like creature * prehensile wing, arm, prehensile fin: A 4-armed aquiline creature like a swimming crab * prehensile wing, arm, flipper-leg: An amphibious 4-armed winged humanoid * prehensile wing, leg, leg: An avian quadruped with hands * prehensile wing, leg, prehensile foot: An aquiline quadruped with hands * prehensile wing, leg, flipper-leg: An amphibious avian quadruped with hands * prehensile wing, wing, leg: A 4-winged avian creature with hands. * prehensile wing, wing, fin: A fully aquatic 4-winged duck-like creature with hands * prehensile wing, wing, wing-leg: A 6-winged tetrapteryx with hands * prehensile wing, wing, flipper-leg: An 4-winged amphibious avian creature with hands * prehensile wing, wing, flipper-wing: A duck-like tetrapteryx with hands * prehensile wing, fin, fin: A fully aquatic duck-like quadruped with hands * prehensile wing, fin, flipper-leg: A duck-like humanoid with hands * prehensile wing, prehensile foot, leg: An ape-like avian quadruped * prehensile wing, prehensile foot, prehensile foot: Another ape-like avian quadruped * prehensile wing, prehensile foot, flipper-leg: An ape-like amphibious avian quadruped * prehensile wing, prehensile wing, leg: A 4-winged avian creature with 4 hands * prehensile wing, prehensile wing, fin: A fully aquatic 4-winged duck-like creature with 4 hands * prehensile wing, prehensile wing, prehensile foot: A 4-winged aquiline creature with 4 hands * prehensile wing, prehensile wing, prehensile fin: A fully aquatic 4-winged aquiline duck-like creature with 4 hands * prehensile wing, prehensile wing, wing-leg: A 6-winged tetrapteryx with 4 hands * prehensile wing, prehensile wing, flipper-leg: An amphibious avian creature with 4 hands * prehensile wing, prehensile wing, flipper-wing: A duck-like tetrapteryx with 4 hands * prehensile wing, prehensile fin, prehensile fin: A 6-armed flying fish * prehensile wing, wing-leg, leg: A 4-winged dragon with arms * prehensile wing, wing-leg, wing-leg: A 6-winged dragon with arms * prehensile wing, wing-leg, flipper-leg: A 4-winged amphibious dragon with arms * prehensile wing, flipper-leg, flipper-leg: A sea-dragon with arms * prehensile wing, flipper-wing, flipper-wing: A flying fish with arms * prehensile fin, fin, fin: A 6-finned fish with arms * prehensile fin, fin, prehensile fin: A 6-finned aquiline fish with arms * prehensile fin, fin, flipper-leg: A humanoid fish * prehensile fin, prehensile fin, fin: A 4-armed fish * prehensile fin, prehensile fin, prehensile fin: A 6-armed fish * prehensile fin, prehensile fin, flipper-leg: A 4-armed humanoid fish * prehensile fin, flipper-leg, flipper-leg: An ichthyocentaur * prehensile fin, flipper-wing, fin: Another flying fish with arms * prehensile fin, flipper-wing, prehensile fin: An aquiline flying fish with arms * prehensile fin, flipper-wing, flipper-leg: Another winged humanoid fish * wing-leg, leg, leg: A 6-legged bat-like creature * wing-leg, leg, prehensile foot: An aquiline 6-legged bat-like creature * wing-leg, leg, flipper-leg: An 6-legged amphibious bat-like creature * wing-leg, fin, flipper-leg: An aquatic bat-like creature * wing-leg, wing-leg, leg: A 4-winged bat-like creature * wing-leg, wing-leg, prehensile foot: A 4-winged aquiline bat-like creature * wing-leg, wing-leg, wing-leg: A 6-winged bat-like creature * wing-leg, wing-leg, flipper-leg: An amphibious 4-winged bat-like creature * wing-leg, flipper-leg, flipper-leg: Another amphibious 4-winged bat-like creature * flipper-leg, fin, flipper-leg: Another sea-dragon * flipper-leg, flipper-leg, flipper-leg: An aquatic insectoid * flipper-leg, flipper-wing, flipper-leg: Another sea-dragon * flipper-wing, fin, fin: Another flying fish * flipper-wing, fin, prehensile fin: Another aquiline flying fish * flipper-wing, fin, flipper-leg: Another winged humanoid fish * flipper-wing, flipper-leg, flipper-leg: An avian quadruped fish * flipper-wing, flipper-wing, fin: Another flying fish * flipper-wing, flipper-wing, prehensile fin: Another aquiline flying fish * flipper-wing, flipper-wing, flipper-leg: Another flying fish ]
[Question] [ The first archetype that comes to mind is: **Coexistent Primary and Secondary World (both on planet earth)**: The writer usually makes up an excuse to explain why the "Muggles" don't know about the fantasy world (like in *Harry Potter*, *Artemis Fowl*, *The Magicians*, ...). I'm not an expert fantasy reader, therefore I'm asking for a list of possible models to connect the two worlds in urban fantasy. It would be nice to add an example for each archetype. [Answer] An interesting model I came across (in the webserial midnight moonlight - not always SFW) postulates that magic means shaping some energy with your intent - and magical rituals and the likes work because people expect them to work, so *everybody* is constantly emitting intent towards those rituals. Well, everybody who knows about magic contributes to the magical rituals - but far stronger (due to higher numbers) is the belief of most humans that magic does NOT work, and mystical creatures do not exist. This leads to people who do not believe in magic being protected by what is essentially billions of people constantly casting tiny "Magic and mystical creatures cannot directly affect us" spells. But mystical creatures ARE real, and some of them are rather nasty. So the people "in the know" try their best to avoid having civilians realize that magic IS real, which would make them lose that protection - anyone who gets dragged into the mystical world has to work quickly or get powerful help to build up other protections from the fae and such. [Answer] **Separation initially due to witch hunting that maintain throughout centuries:** In our world, we have an historic of witch hunting and exterminating different people, so we can imagine real magician would be persecuted worldwide. If the muggles/magician ratio is favourable to muggles, even with offensive magic, the magician will not be able to take control of muggles society. Consequently, in order to avoid persecution, magicians will start to hide from muggles, thus creating their secret society. Over time, magicians will gradually improve theirs hiding capacities to the point that muggles are no longer able to find any magician and start thinking they where exterminated. After that, the existence of magic will slowly change into a myth in Muggles society while magician society keep hiding, convinced that detection by muggles will lead to theirs extermination. Thereby, we get a society where muggles think that magic isn't real and magician don't want to be discovered and live in an hidden society. [Answer] The archetype you mentioned of coexistence worlds is by far the most common one in fantasy literature. Another one I can think of is where the magical world exits at a certain time. This can be seen in Stig of the Dump, the BFG and other children's literature(Not exactly urban fantasy but they illustrate the concept well enough). Can't think of an example from adult/YA literature right now. The next one is two different worlds one of which is out own that begin to crossover. In general the two worlds have nothing to do with each other until the story brings them together. Elidor would be an example of this. The final kind is that the two worlds know each other and the setting is just our world with some fantasy characters chucked in. For this look at some superhero books/films. [Answer] Muggles neutralise the power of magic users. Magic users can only use their powers when there's no Muggle around. This is like quantum mechanics where a measurement collapses the wave function. The presence of a Muggle collapses magic. Magic users live in their own communities safe from Muggles and where they work magic effectively. This may explain urban fantasy worlds similar to the Potterverse. Vampires, werewolves, and other undead apex predators might need to lie low to survive. They usually have powerful weaknesses (garlic, running water and stakes through the heart, silver for werewolves, & salt for zombies etc) making them extremely vulnerable to any systematic counterattack by organised humanity. Perhaps reality cannot tolerate more than an extremely small number or low density populations of supernatural beings (magicians, vampires, etc etc) in any one place. Too many of them and they self-destruct or competition becomes too strong. The supernatural ecology can't support too many of them. Fantasy worlds like these are just counterfactual set-ups so supernatural can collide with the contemporary reality. Writers should have fun with that, going too deeply into why of such worlds only exposes their fundamental absurdity. Not that there's any wrong with absurdity. [Answer] There's also the underworld model (not specifically referring to the Underworld movies though they are applicable) in which the fantasy beings are either predatory (vampires, werewolves, etc), incompatible with civilised society (ghouls and undead in general) or unwilling to participate in lawful society (fey). [Answer] In most stories magic and/or magical creatures are kept hidden from the ordinary word by the government or some other powerful organization (the vampire counsel or the magical congress of America). This done usually for three possible reason. 1. To prevent a war between normal's and magic user/creatures. If the normal people know about magic they might see those who can use it as a threat, while those with magic our more powerful, but the normal have the numbers. 2. To prevent a panic: If the government keeps information about potentials terrorist attacks secret because it might cause a panic, why not keep magic secret for the same reason. 3. To keep magic out of the wrong hands: Magic has the potential to turn anyone into a super weapon. That not something that you want to release to the public. [Answer] ### There are multiple worlds with some gateways between them The *Otherworld* series by Jasmine Galenorn offers a way for fantasy creatures to come into our world by stating that there are in fact multiple worlds that are very closely tied together at a few points. These are basically gateways that allow people or creatures from one place to pass through to the other side. Over time both sides decided that it would be a good thing to keep track of these portals so that people that have something nasty in mind won't easily pass through and wreak havoc on the other side. This leads to gatekeepers that keep the fantasy population on "our" side in check. Both sides also realised that there are certain cultural differences, which makes communication very difficult. Modern humans are not known to be nice towards nature spirits for example, so contact is often prohibited or at least very limited. Basically it's just a couple gatekeepers and people-who-don't-*really*-belong-on-the-other-side that you will find on our side and they keep an eye on evildoers because they like their life here and don't want humans to start a new witch hunt. You can then either have both sides strictly divided or have them realize that the other side exists and that there can be an advantage to cooperation, depending on whether you want a "unknown creatures of the night" kind of experience or a "new fantasy creatures and how they have always been among us" kind of experience. ]
[Question] [ I'm interested in asteroid mining, but don't have the infrastructure in place to process ores and the like in space. However, I've got a nice planet-based refinery setup where I could easily process an asteroid, except for one problem: it's on a planet, and my asteroids are in space. I'd like to get my asteroids, which vary in composition, but are generally between 50 and 300 meters in radius, from their high-speed orbits around the sun onto the surface of my planet, which has a similar size, gravitational pull, and atmosphere to Earth. I'd also like to do so without destroying huge tracts of land, causing tsunamis, triggering extinctions, or any of the other general badness that usually comes when asteroids deorbit themselves into the ground. What's the best way for me to go about doing this? How can I deorbit and 'catch' an asteroid without anything horrible happening? [Answer] Capturing an asteroid would consist of several steps... **Identify** The easiest asteroids to capture are going to be the closest, slowest rocks with the least amount of rotation, so these will be prime candidates. You will also want rocks with relatively soft surfaces for the next step. **Capture** Capturing a rock is fairly simplistic if you think about it, assuming you've identified good rocks. This will be easiest with at least three ships or drones, each equipped with harpoons. The harpoon will need to propel an anchoring hook into the surface of the rock, with the cable fitted to a swivel between the cable and the ship. Ships could then control velocity and rotation, so that the rock can be towed back to the home planet. **Delivery** Once the home planet is reached, the ship(s) place the rock into geosynchronous orbit with a space elevator specifically designed to handle the weight of the rock. A traditional elevator for ferrying people would not suffice, as the descent mechanism would need to be much stronger, possibly even rocket or anti-gravitation assistance to slow down descent. Most of this could be plausible with a slight leap in current technology, eliminating the need for any explosives in space. [Answer] You could try to destroy the asteroids in space and collect the fragments. Smaller parts are easier to transport and process. You could also send spaceships with roof-mounted thrusters to the asteroid and basically attach them as thrusters to the asteroid. You can also construct standalone thrusters on the asteroid's surface. This might enable you to steer the asteroid and slow it down. This option requires a pretty high technological development and also a good amount of resources to start with. Another option (for civilizations with even higher technological development) could be using eddy currents to slow the asteroids down (at least the metallic ones). I am not sure how and whether this would work with objects as heavy, big, fast and irregular as an asteroid though. You would probably need tremendous amounts of metal and energy to build and power a device that can create a magnetic field this strong. It might also destroy your planet, so you better build it very far away from it or go with one of the less crazy options. [Answer] By high speed orbits, you mean they orbit closer to the star than your planet, right? Getting machinery there is the costlier part, in terms of energy. A lot of delta-V involved. You have to match their orbital speed in order to dock to them. This involves two problems: * it is a huge change of speed; * due to the former problem, it takes a lot of fuel... But in order to take large amounts of fuel anywhere in space, you have to burn more fuel (every bit of fuel is a payload until ou use it). Essentially your problem is similar to that of catching the Voyager and bringing it back home, [as seen on XKCD](https://what-if.xkcd.com/38/). Only you want to go to a lower orbit and back, instead of going through a solar escape trajectory and back. There are ways in which you can solve those problems. Mining done exclusively by drones keeps weights needed to operate low, and it means you can use an acceleration rate that could kill humans. You can also sacrifice your miners with less ethical implications if they are disposable drones. As for fuel, [Nasa is testing an engine that does not require the ejection of mass in order to accelerate in space](https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster). That's witchcraft to many scientists, but just goes into showing that you probably don't need to handwave at all to have mining ships of reasonable sizes to reach those asteroids (really, go read that XKCD article and check the figures!). One last thing. Keep your masses as low as possible. Don't bring the asteroids whole back home. Have the drones separate ore from useless rock. Bring only the ore back home. If your ships launch from the surface of the depleted asteroids, they will also push whatever's left into lower orbits, potentially making the "mining orbits" safer. To bring the ore to the surface, put it in orbit of your planet first, then have space shuttles take it in chuncks to the planet surface - make it a regular service, just like Space X takes payloads to and from the ISS on a schedule. It then turns into a matter of having enough ships to keep your business productive. [Answer] The fastest and quickest way would be to plant a few nuclear weapons on the surface and detonate then timed to decelerate the asteroid so that it can get caught in the planets gravitational field instead of flying off into oblivion. You do run the risk of catastrophic failure with some ill-timed blasts, but hey, story options and plot devices abound with this method. Just remember, who controls the WMD's required for asteroid moving? The second option is to have specialized spaceships with either reinforced noses or payloads of rockets and mass drivers to serve the same purpose. Have the spaceship chose an asteroid to move, dock with it, and either brace itself and fire the engines to push it into orbit, or deploy the rockets and mass drivers to push it into orbit. It could all be manned, or automated. Further reading on AtomicRocket can get you more information about this issue. Hope it helps. [Answer] You need a space elevator. Break the asteroid into pieces and send loads in the *down* cars. Furthermore, these will act as ballast to use in lifting *up* cars for free. More generally, you have a problem with *energy*. If you use the planet to slow and stop the rock, even using controlled aerobreaking rather than a messy impact, you are transferring all that energy onto the Earth. It doesn't matter if it's one rock or dust, the result is the same. You can start by reducing its orbital velocity to zero while still in space, using means where the re-action (e.g. rocket exhaust) misses the Earth. Then you still have to lower it to the ground, and that has an inherent amount of potential energy which is converted to heat. If it drops to the ground it leaves a big crater, but if you use a parachute (or [whatever](http://www.explainxkcd.com/wiki/index.php/1243:_Snare)) it still impresses the same amount of energy onto the air and eventually the Earth as a whole. If done on an industrial scale, this could be the future's equivilent of burning fossil fuels. Before a full space elevator is built, you can consider a mere 80 mile long tether. Well, since the platform above will have difficulty thrusting in a manner which doesn't just transfer the exhaust to the air below, it will actually need a much longer tether to lower the rock as the platform continues to speed by at orbital speed. Importing material will be expensive, and this will drive more industry *into* space. Your postulated situation is unrealistic: the rock will be (far preferentially) be mined and refined *in space* or on the Moon. Asteroids can be found that are made of metal, so start with those and you don't have *ore* that needs refining as with Earthly mines; not at all. Metal foundries can work on the Moon and provide stock and finished parts for space-based industry. I'm sure they will still like steel for *something* even though they mostly use carbon and composites. The real profit will be for platnum and other rare metals that are used in industry but in much smaller quantities. Landing this will be much less of a problem because of the orders of magnitude smaller quantity and the high price of the material. ]
[Question] [ Imagine a laser capable of melting through a 1 inch steel plate [in a second](https://www.youtube.com/watch?v=WWK4rKYpYcY). Pretty impressive, no? Good, now make it **100,000 times more powerful**. That's gamma rays. Recent tremendous advances in linear accelerator miniaturization (LAM) have completely revolutionized our capability to **produce gamma\* radiation cheaply and abundantly**. Photon energy levels previously only attainable in distant cosmic object like magnetars, black hole accretion disks or as bremsstrahlung radiation in the most powerful cyclotrons of the previous decade (2010-2020) are now attainable in a vehicle-portable tabletop sized device. Due to the rapidly deteriorating security situation in the world, it is perhaps not surprising that the immediate application of the LAM technology is in the military area. With the involvement of DARPA and a number of secretive startups, the US has developed a lead in the field, and the most public of the startups has unveiled a prototype to US CENTCOM, where they estimate that a 1-meter diameter fixed-sentry (journalists quipped that it was shaped a bit like a Dalek from Dr. Who, minus the wheels) can be built for $50,000 and, with an appropriate power source, is capable of near-continuous (90-95% uptime) devastating fire in the MeV range ("fluorescence" is the current euphemism) with virtually no maintenance for up to 1 year unless physically damaged by enemy fire. The latest version also boasts impressive angular velocity and target acquisition and engagement speed is so fast that is it said that a human cannot actually see it move. While the US pioneered the technology, US adversaries are working overtime to replicate the technology, and the most advanced will probably succeed in doing so in the next few months/years. Already unreliable, overheating prone, lower-power versions have popped up in the arsenals of non-state actors in the never ending conflicts in West Asia. **What would the main effect of such gamma-ray sentries be on the battlefields of the near-future? Can maneuver warfare persist under these constraints?** \*Gamma rays are [extremely high energy](https://www.physicsforums.com/threads/gamma-ray-laser-possible-superior-weapon.650910/), typically thousands to millions of electron-volts per photon, compared with 1.5-3 electron-volts per photon for visible light. So like light, except a **million** times more powerful, heh, heh. [Answer] Expanding on John Robinson's answer, there are quite a few difficulties that the proposed Gamma Ray device will have, making it's use different from what you seem to be proposing. First off, we see the amount of energy required to power the device, and the short time periods involved in creating the gamma ray burst or beam. This means while the device itself might be the size of a Dr Who Dalek, it will need to be attached to something capable of providing massive amounts of energy and support (such as cooling). An aircraft carrier might be an appropriate vehicle to carry one of these. The second thing to consider is that gamma radiation, and indeed high energy radiation beyond ultraviolet is rapidly absorbed by the atmosphere, limiting the range of the gamma ray device. If I can move into range with an artillery piece or long range guided missile and strike the emitter before I am in the range of the gamma rays, then the gamma ray weapon is essentially nullified. Even if the gamma rays are of sufficient power to fry electronic guidance systems or prematurely detonate warheads, all I have to do is fire lots of "dumb" rounds and saturate the area where the gamma ray weapon is located. A concrete practice round will still strike the emplacement with a lot of energy and damage or destroy the delicate internal mechanisms of the gamma ray emitter. [![BM-21](https://i.stack.imgur.com/XF5Br.jpg)](https://i.stack.imgur.com/XF5Br.jpg) Looking at the problem fem this angle, I can see a modification to your assumptions is needed, but fortunately(?) will still have much of the same effect. There are already devices called "wake field accelerators" (see: <https://portal.slac.stanford.edu/sites/ard_public/facet/Pages/rpwa.aspx>, and <http://www.slac.stanford.edu/pubs/slacpubs/3750/slac-pub-3891.pdf>, for example) which can accelerate beams of electrons in the space of a fraction of a metre. [![Plasma Wakefield accelerator](https://i.stack.imgur.com/DVOhJ.jpg)](https://i.stack.imgur.com/DVOhJ.jpg) These high speed electron beams are the heart of "Free Electron Lasers" (FEL) which have high "wall plug" efficiency (up to 60% of the energy can be converted to laser light) and are "tuneable" to frequencies that you desire. The FEL can be tuned to fire through one of the "windows" in the atmosphere which are not highly absorbent of laser light; the primary stipulation is you keep the beam energy low enough to prevent the atmosphere from breaking down into a plasma and absorbing the beam. A rapid pulse rate reduces this problem and also applies high energy shocks to the target, so in addition to thermal damage and the erosion or vaporization of the target material, mechanical shocks will also be weakening the structure. [Answer] Note: I'm no expert on radiation, I'm just going off of what I remember from my time as a physics major in college. We played around with low-energy gamma rays in an experimental physics class, but I don't have firsthand experience with high energy physics. First, a background in radiation and some math. A dose of 10 Sv (enough exposure to gamma radiation to add 10 Joules of energy per kilogram of matter) is lethal beyond medical help - even bone marrow transplants or other major surgeries won't help you. So let's use that as our reference point to calculate how much energy these turrets are actually putting out. We'll need that in order to figure out how much energy output we're dealing with. Supposing an 80 kg soldier, the turret needs to hit them with 800 Joules. That comes out to [about $5\times 10^{15}$ MeV](http://www.wolframalpha.com/input/?i=800%20joules%20to%20MeV). A normal light bulb can emit on the order of [$2^{20} photons per second](http://www.eg.bucknell.edu/physics/astronomy/astr101/prob_sets/ps6_soln.html) (see problem two), so assuming that our turrets are on the order of 1 MeV per photon (as per OP), this energy transfer would definitely happen in less than a second. They'd probably be a bit more energetic than that, though, because a) a second is a long time in a fast-paced battle and b) some energy would be lost to the air, so better to be more energetic. There are two types of absorption that we care about: Compton Scattering and Pair Production. [Compton Scattering](https://en.wikipedia.org/wiki/Compton_scattering) is the easy one. In simple terms, when the gamma ray hits something, it loses some of its energy and moves in a slightly different direction rather than straight forward. Pretty basic. However, things start getting weird at 1.02 MeV. Above that energy, there's a chance that when the gamma ray interacts with something, it will [create an electron-positron pair](https://en.wikipedia.org/wiki/Pair_production). This is Pair Production. The positron will then annihilate with an electron, creating two gamma rays with half the initial energy (ie a 1.02 MeV gamma ray goes through pair production and becomes two 0.51 MeV gamma rays after the positron annihilation). Those lower energy gamma rays will then undergo Compton Scattering until their energy drops off. Well then. How does all of this apply? The best way that we know of to protect against gamma rays is simply putting as much stuff between it and you as you can. In general, one centimeter of lead will reduce gamma ray intensity by 50%, though the exact amount depends on the energy of the gamma ray. So the first thing anyone attacking one of these turrets would want to do is to get behind something, or inside something. I can see soldiers being transported in bulky carriers, where the majority of the mass of the carrier is simply shielding from the gamma rays. On disembarking, the soldiers would need to have shielding of their own. Due to the inexorable crawl of technology, I can imagine that it wouldn't be too long before we started suiting soldiers up like the [Thor unit from Starcraft](http://starcraft.wikia.com/wiki/Thor). (Yes, I went from citing high energy physics to citing video games. Fight me.) Depending on how long it takes to get the turrets mobile, eventually we would decide that it's better to just not have soldiers on the battlefield, and to instead have soldiers be remotely controlling the turrets. Remote-controlled warfare: the future is now! ETA: Maneuver warfare could still exist for sure. It would just require an awful lot of planning, and probably some distraction drones that are used purely to draw the turrets' fire while the soldiers did their own things. The fact that currently the turrets are not mobile themselves means that they're only really usable to defend fortified holdings. [Answer] # You will be shooting air Just like visible photons, gamma interacts with air. [Air absorbs gamma](https://en.wikibooks.org/wiki/Basic_Physics_of_Nuclear_Medicine/Attenuation_of_Gamma-Rays). So — when extrapolating into the MeV range from the table on that page — for every 100 meters away your target is, you will be putting half of your **remaining** energy into the air. At 1000 meters, your gamma ray is 1/1000 of what it was at the gun. This of course means that you heat the air immensely, which will distort it and obscure the target. Absorption, obscuring and blooming are known problems with [directed energy weapons](https://en.wikipedia.org/wiki/Directed-energy_weapon). In short: this will mostly just punch holes in the air. [Answer] One problem is radioactivity. A battlefield after gamma-ray weapons have used will be highly contaminated just like places where nuclear weapons were detonated. Many elements will absorb gamma photons into their nuclei, leaving radioactive by-products. With air absorption, the fall-out will be far and wide. The military force deploying gamma-ray weapons could be harmed to degree comparable to the forces on the receiving end. Arms Limitation Treaties will be either set up or called for to ban gamma-ray beam weapons. If that doesn't happen, you can expect a massive outcry in the aftermath if your gamma-ray guns are used near any civilian population. Think what would happen if Hiroshima or Nagasaki were nuked today in the current Age of Media, the impact would be similar. Also, soldiers themselves will become peaceniks too. They will have seen the causalties and the own wounded of both sides of combatants. Radiation sickness isn't pretty. Deployment of gamma-ray weapons will be hazardous. Few soldiers will want to be targeted by weapons of this kind. In general, no weapon is used in isolation from politics. The deadlier the weapon, the more heated the politics. Remember of the history of the politics of nuclear weapons and the Ban the Bomb movements. Get Rid of Gamma Guns coming up real soon now. [Answer] The only sure effect of widespread use of such a device is, if it is effective, an arms race where advancements in anti-gamma ray protections are constantly fighting against advancements in gamma-ray production. [Answer] If the projectors aren't mobile, then I imagine most battles will start with an artillery barrage -- not to soften up the target, but just to throw up enough dust and smoke to diffuse the beams. Some kind of adaptation of night-vision goggles or VR enhancement to permit troops to fight in the smoke. Maybe all troop carriers would be equipped with steam generators to shroud them in fog and dissipate the beams enough that their (reflective?) armor can hold out for several minutes. ]
[Question] [ If some super-advanced, spacefaring race could carve an asteroid into the right shape, and launch it at the right angle and velocity, would it be possible to “skip” the asteroid off of a planet’s atmosphere, like you would skip a stone off the surface of a pond? How big or small would it have to be for this to work? What would the effect upon the planet’s surface be? Would it be catastrophic, or would the effects be minimal? Could this be used as a weapon? To simplify things, I’m going to focus on what would happen if we tried this on earth, so I don’t have to worry about how things might shift with different atmospheres, planet sizes, gravities, and et cetera. That being said, if it wouldn’t work on earth, what qualities would a planet need so this would work? Also, for the sake of semantics, my definition of “skipping” is the asteroid *never* actually making contact with the planet’s surface, and not just blazing through the planet’s atmosphere in a straight line without being diverted in any way. The asteroid has to be deflected by the atmosphere itself, not the planet, and skip off at a noticeable angle. [Answer] It is indeed possible. You'd need a very particular shape, though, and you'd need to hit the atmosphere at just the right angle. **Short explanation:** It would look much like a flat stone being thrown at a calm lake surface. It will bounce off. **Long explanation involving physics:** (I hope you understand basic orbital mechanics) It's more complicated than a lake. As the body enters the atmosphere, it starts generating aerodynamical forces - mainly lift and drag. Under normal circumstances, the drag is enough to slow the object so much that it cannot fly on itself. If it enters under a shallow angle and has a good shape, the lift it generates will be enough to pitch it up and gradually push it out of the atmosphere. It doesn't end there, however: The drag has acted at the object, possibly slowing it down. Which means that it's no longer at an orbital velocity, and returns back to earth. The skipping then repeats itself until it's not flying fast enough to generate enough lift. If you threw the asteroid hard enough, however, and hit the atmosphere under a shallow angle (Think an highly eccentric elliptical orbit, with its periapsis right at the edge of the atmosphere), it would bounce off and change its trajectory. The change will not be too big, though. It's not like it would bounce off to outer space, it's more like the periapsis rising (or dropping, depending on the angle) by several kilometres. [Answer] Since no one else has mentioned it, not only can it happen, it did. August 10, 1972. Since there was no inter-webs back then, the news articles about it are not necessarily available, but here are a few reasonable references: * [Wikipedia](https://en.wikipedia.org/wiki/1972_Great_Daylight_Fireball) * [NASA's Picture of the Day](http://apod.nasa.gov/apod/ap090302.html) * [Some guy's blog](http://astrobob.areavoices.com/2013/08/30/spectacular-mexico-meteor-recalls-great-daylight-fireball-of-1972/) * [on online homework question](https://www.chegg.com/homework-help/questions-and-answers/august-10-1972-large-meteorite-skipped-across-atmosphere-western-united-states-canada-much-q10704361) [Answer] **TL;DR:** Finally, my years of experience in Kerbal Space Program pay off. It's possible to do, but won't do much compared to just blazing through the atmosphere. As @TimB mentions, you can't "skip" an asteroid from the atmosphere quite the same way as you would skip something off the surface of a pond. You can, however, make use of the atmosphere to change your trajectory and effect a "bounce". ## Theory To get an idea of how this effect would work, let's forget about planets and orbits and work for the moment with an infinite flat plane with a homogeneous gravitational field. Even if you fire it of with a lot of horizontal velocity, it will eventually just drop. Add atmosphere and it just gets slightly slowed down towards the end. If instead of an asteroid you use a glider, however, you have options. The most straightforward one is to pull up, which will under favourable circumstances get you back out of the atmosphere again, but with less velocity. You may be able to repeat this process, but eventually you'll just glide down. We can do something similar with an appropriately shaped asteroid. To planets now. We won't be doing any "slingshots" or "gravity assists", since those don't actually require an atmosphere and don't work in two-body systems anyhow. What happens when a spherical asteroid passes sufficiently close to a planet to dip into the atmosphere (but not so close as to hit the planet) is that it slows down some, losing velocity (and thus energy) to aerodynamic drag. This changes its orbit; doing it on purpose is called "aerobraking" and if the orbit goes from hyperbolic (ie. speeding back into space) to elliptic, it's called "aerocapture". It's not, strictly speaking, "skipping off", since it's not the atmosphere bouncing you off, it's orbital mechanics carrying you away. Now the thing to understand is that your orbit is at any given point fully determined by your position relative to the body you're orbiting, and your velocity relative to that same body. Aerobraking changes your velocity, generally just by braking, which has the effect of shortening your semi-major axis (bringing you to a "lower orbit") and bringing your periapse down some, as both horizontal velocity and vertical velocity are affected equally. At this point, using wings (and the golden rule of aircraft design tells us that at these velocities, *anything* is a wing) you can cause the drag to be asymmetric, gaining what we call "lift". Note that it's impossible for you to gain energy this way, the only thing that's happening is that you're trading some of your velocity to change the direction of the rest of it. You can take advantage of this to change the altitude of your periapse (and hence the eccentricity of your orbit) or effect a plane change, but you'll lose energy doing so. ## Applications If you have a controllable aerodynamic shape, you can take advantage of a planets atmosphere to alter your trajectory at no cost in propellant to you. Apollo capsules (IIRC) took advantage of this; by having a centre of mass slightly offset to the side from the geometric centre of the capsule, they would get carried away slightly to the side in an atmosphere, and could rotate the capsule lengthwise to gain some limited control authority. I have taken advantage of this trick to keep the periapse of a moon lander in the high atmosphere during multiple aerobraking passes on a return from a moon, allowing me to gently slow down and rendezvous with a space station in orbit of Kerbin at a minimal cost in propellant. Could you use this as a weapon? Maybe. The energy expended in these maneuvers manifests as shock heating and is usually absorbed by the orbiting body, so the effect on the planet is limited. But what if there was enough of it? This begs the question of how much energy this maneuvre consumes. We can get the answer from the [vis-viva energy equation](https://en.wikipedia.org/wiki/Specific_orbital_energy). Taking the initial orbit and calculating the energy (multiplied by the mass of the asteroid), we get the maximum energy we may deposit by deorbiting (read: crashing into the planet). The difference between the energy of this orbit and the new orbit is how much energy was expended/deposited. For Earth-like planets, just attaining escape velocity compared to sitting on the surface gives you an energy $-62,6 MJ/kg$ which is about $15x$ the energy of TNT. Impressive at first glance, but not much in the grand scheme of things, especially if you consider that you're only expending a tiny part of this energy (however much you're willing to sacrifice without falling) an most of it will be absorbed by the asteroid. Perhaps a better use of this capability would be to just drop some kinetic impactors (like tungsten rods) to do some damage and then use the planetary atmosphere to fine-tune your trajectory to your next target. Oh, and since you were asking about the shape of the asteroid: it would probably end up being vaguely reminiscent of a space shuttle if you wanted to optimize, but unless you dip too deep, any shape with asymmetric drag or control surfaces would do, albeit with less efficiency. [Answer] While [intercity](https://worldbuilding.stackexchange.com/a/38216/49) is not wrong I'm skeptical that you could make it work in reality. There is a big difference between the atmosphere and a lake. In particular the lake has a hard transition surface that you can use surface effects on to skip a stone. The atmosphere has no such effects, and it is very hard to conceive a situation where you would generate enough lift that it would counteract the drag of passing through the atmosphere. Dipping into the atmosphere is a great way to shed speed and is called Aerobraking but it's going to slow you down by doing so. The only thing similar is called [gravity-assist](https://en.wikipedia.org/wiki/Gravity_assist) which is essentially skipping off a planet but it uses the gravity well, not the atmosphere, to do it.. [Answer] Not only it is possible, it happens all the time. Here is a tweet showing it in action, from September 2020: <https://twitter.com/meteordoc/status/1308553949255999489> There is a similar question in space.se: [How does skipping off the atmosphere work?](https://space.stackexchange.com/q/3068/16652) And the best answer has this interesting tidbit: > > However lift is not required for "skipping" out of the atmosphere, since unlike the apparent surface of a pond, the atmosphere is curved. All that is really meant in the case of a skip entry is that the entry flight path angle was not steep enough to prevent the object from leaving the atmosphere again. The trajectory of the ballistic skip flight does not curve up like that of a skipping stone. It still curves down. However the radius of curvature is greater than that of the radius of curvature of the atmosphere, so it departs back into space. > > > (...) > > > Skip entries can also be used to spread out the total heat load of an entry over multiple passes, allowing cooling between passes. The aerobraking approach used by several [Mars orbiters](https://dx.doi.org/10.2514/6.2002-4821) is an extreme example of many high-altitude skip entries. > > > Do check that last link, as it shows how we humans have used the effect in an engineering feat. ]
[Question] [ I am writing a novel and I am working on the design of a castle that is defending a long wall at the border of a land to prevent invaders. I am currently trying to think of the design of the castle, because it is essentially part of the wall, to help defend it. I can't decide on a good design for it. I considered a concentric style castle, but then I realised that if they retreated to the inner wards, it would just leave the invaders free to enter the lands and ignore the inner wards. Does anyone have any good ideas? [Answer] There are some real-world solutions for this: * [Hadrian's Wall](https://en.wikipedia.org/wiki/Hadrian%27s_Wall), made in the days of the Roman Empire (122 AD erm... CE for you politically correct types), to defend Britania from picts and other unconquerable people in the north. They placed small, fortified positions along sections of the wall. Furthermore, these smaller fortified sections had the potential to call for backup from Housesteads, which looked something like this: [![Housestead floor plan](https://i.stack.imgur.com/Eo2ZA.jpg)](https://i.stack.imgur.com/Eo2ZA.jpg) Note that the *north gate* and wall were part of the actual wall. One could easily see these housesteads acting like castles; strong points along the wall where one can hide from potential invaders. Alternatively, these housesteads could have been strong points to march out of and to retreat to. * [The Great Wall of China](https://en.wikipedia.org/wiki/History_of_the_Great_Wall_of_China#Han_dynasty_.28206_BC.E2.80.93220_AD.29) had forts in addition to watch-towers and battlements. We often see the smaller watch towers, which would in turn signal other towers, allowing larger forces, which were garrisoned in forts, to meet the opposing enemy. Perhaps the most important thing about really long walls is that they are a gamble to buy time and restrict enemy movement. The wall prevents enemies from freely moving in and out of lands, and prevents large forces from simply marching through an area. The extra time it takes for large forces to go through the wall is spent by the defenders amassing enough troops to stop the invasion. This castle along the wall could simply be a place for this response force to live, like the housesteads on Hadrian's Wall. [Answer] Real-world examples have already be shown by previous answers, then here are a few thoughts : **There should be several small castles along the wall**, more than a big one somewhere, in order to protect a long wall. Now let's take only one of them. Its efficiency does not only depends from how your castle is build, but where it is build. I assume that when the enemy reaches your land, he wants to pass you wall and go behind. Thus, there is no interest in attacking or destroying your castle if it can be avoided. Find were your enemy would try to invade your land if there were no wall at all : probably a large plain or valley, where an army can pass easily. **Put your castle(s) where it annoys the travelers most** On the top of the hills, filled with archers. That place where the river is less deep. Right above this narrow passage. Previous fortifications could force your enemy to go on a certain way. If there is not only one way, you can make one of them seems easier. **Protect the wall** Keep in mind that if the enemy army can both push your own army deep behind the walls on your castle and still attack the wall outside, where they are tighter, they might be too numerous to be stopped (for your circular walls idea). You can not hide your castle behind the wall if your goal is to protect the wall. You said your castle was part of the wall, but it doesn't have to be entirely behind. The more forward it is, the more outside land its arrows can reach. If you make concentric walls, a part of the wall can only protect itself and not the other. You could try something like a star (where each branch can cover the others) inspired by fort Vauban : [![enter image description here](https://i.stack.imgur.com/hVBQR.jpg)](https://i.stack.imgur.com/hVBQR.jpg) It doesn't have to be triangular, you could have several walls like a comb, with archers on the top. If there are several small branches, if the enemy destroys or take one of them you still have the others. With concentric walls, once they are in, you have to go back. Think about machicolation, especially if you manage to put your castle on the heights. [Answer] One thing you might need to clarify, which will greatly affect the kind of [fortification](https://en.wikipedia.org/wiki/Fortification) you will need, is this: What level of weaponry are you looking at giving the attackers and defenders? An army using spears and stones will need a different defensive structure to an army equipped with artillery, snipers, tunnelers, air support, nukes. Unless your wall extends completely from one end of your country to the other (and even then you've still got problems) it can simply be bypassed by going around the sides, as the Germans did in WW2 with the [Maginot Line](https://en.wikipedia.org/wiki/Maginot_Line). The [Great Wall of China](https://en.wikipedia.org/wiki/Great_Wall_of_China) didn't stop the Mongol invasion, nor did the [Atlantic Wall](https://en.wikipedia.org/wiki/Atlantic_Wall) stop the allies from getting into France in WW2. Admittedly the Atlantic Wall wasn't actually a wall, but a series of complementary fortified positions. The main thing you'd be looking for would be converging fields of fire along the walls, possibly from buildings projecting from the walls themselves, such as [caponiers](https://en.wikipedia.org/wiki/Caponier) like [this one](https://en.wikipedia.org/wiki/Batterie_de_Bouviers#/media/File:Plan_d%27ensemble_Batterie_Bouviers.jpg). By having a castle disconnected from the wall, you're making it much more difficult the reinforce, resupply or evacuate the occupiers of the castle. Having it connected to the defensive wall by tunnels, walkways etc. gets around that. Any defensive line can be breached at its weakest point (or any point) if you apply enough force to it. Walls and fortresses are costly to build and maintain, require high manpower to protect and cannot be repositioned. But you really need to define the level of weaponry technology in use. [Answer] The issues of walls has been addressed very well by the other answers, so I will look at the castle itself. The main reason to have a large castle is both as a fortification and also as a base. Sitting behind the walls and waiting for the enemy is a passive defense, perhaps appropriate if the enemy outnumber you by a considerable margin, or you are blocking the only approach route (i.e. you are at the head of the only pass or valley leading into your kingdom). If you are more inclined for an active defense, then a large castle provides quarters for cavalry to go out and scout, and men to sally forth to engage the enemy. In your construct, I am imagining a large wall backed by small garrisons, with the large castle farther in the rear, blocking the main access route to the kingdom (perhaps there are other, smaller castles blocking secondary routes. The garrison of the castle rotates with the smaller fortress garrisons, but the main purpose is to send out a force to relieve sections of the wall when it is under attack, or to counterattack forces which have crossed the wall, and potentially sent punitive expeditions across the wall in the other direction. [Answer] If you were designing. Castle to protect a wall. From the castle every Area of the wall would need to be visible and then watched at all times that way any threat would be seen Second, a form of Quick and preferably discrete communication that would rally your troops or army to defend the oncoming threat would be vital. Perhaps the idea is the castle is a decoy where as the wall houses your defenders always prepared [Answer] Medieval castles are basically a wall connecting round (less commonly quadrangular) towers (triangular bastions appear with cannons). In the Iberian peninsula it was common for castle walls to be protected by a second, small outer wall, a barbican. The space between the barbican and the castle wall should be clean of hiding places so that, if the invaders broke through the barbican the defenders on the walls and towers could easily target them. For your particular case, I'd suggest the main wall to consist of short panes between towers. The barbican would be placed in front of it because it will sustain the brunt of the attacks, thus shielding the main wall. There should be forts (which may look like a traditional castle) at regular intervals (within sight of eachother, so that signals with fire and flags can quickly pass messages around) and preferably on high ground. [Answer] Design the castle in accordance with the direction the threat is coming from, and the terrain. Put your barracks and armories closer to where the enemy is coming from, so when you're attacked, you can get to the defenses more quickly. Make sure that your lines of communication and movement are as short as possible, and that you can see everything. Remember, the shortest distance between two points is a straight line. You should level all of the terrain in front of the castle, cutting down every tree and bush, and set fire to any vegetation so that not only does the enemy have no cover, but they also don't have basic survival materials for a siege, or wood to make siege towers and battering rams. Pick a spot, ideally, where the terrain in front is flat, and the terrain behind is mountainous or hilly. Maybe you use a river to defend in the front, or have marshes guard your flanks. You want your forward walls to be rounded, to deflect projectiles, and to make the enemy's attacks be like waves hitting a rock. You also want the castle to be part of the wall, as this will protect you from being outflanked and keep your supply lines open. Remember, a garrison force for the smaller castles along the wall needs only be 1/10 the size of the force attacking it. 1 man can defeat 10, 10 men can defeat 100, and 100 can defeat 1,000, especially if they are defending fortifications. Just remember the principles of geometry, economy of force, and defensive construction, and you'll be fine. ]
[Question] [ I'm writing a story wherein a young woman becomes the lord/lady of a number of villages in a feudal society (she is the vassal to a king). The world is sort-of medieval, with cannons but without muskets. The way she gets this position is kind of complicated, and there is no question that it occurs, even if it doesn't make historical sense. What are the sorts of things she would have to do for her people? I'm not searching for something factually accurate, but just something that seems genuine. I'm more interested in the day-to-day running of the estate, or dealing with mundane emergencies (such as the destruction of crops by weather) than with dramatic things like going to war. Also, what privileges would she be expected to take? What are the duties the vassal would have to the king/overlord? [Answer] **About Feudalism (Section Edited)** In [Feudalism](https://web.cn.edu/kwheeler/feudalism.html), we start at the top with the ruler, who is essentially a landowner. He or she then doles out parcels of land to lesser lords and/or ladies, who are then responsible for the occupants thereof. Depending on the size, you could have many layers, from King, to Lord, to Dukes, to Barons, Counts, Viscounts, even Marquises, and [so on and so forth](http://www.lscacamp.org/portals/0/medieval%20people.pdf). Initially, the Feudal Lord ensured that farmers would be able to farm in peace by keeping a standing force and sending them out to kill bandits, rival forces looking to claim territory, and even packs of wolves or bears that threatened crops and livestock. The knights who became lords were the only ones capable of fighting off these threats, and so therefore became landowners with "tenant farmers". In exchange, the farmers handed over their crops or livestock, as a "rent" or "tithe" or something of that nature. They paid for the privilege of using the land with goods. The only laws were those made by the landowners, and only the laws that could be enforced physically were those that were considered true laws. Over time, the knight became "king" and was able to then dole out land to his trusted family and friends. However, the whole plot of land (the "fiefdom" or "kingdom") was still his and he held dominion over it. Since this is your world, you don't have to follow the strict timelines of the feudal system in our world, but I would like to point out that by the time cannons rolled around we had largely abandoned the feudal system in favor of the monarchy, which is entirely different. **EDIT:** See the comments below for a more realistic description of feudalism. In the early stages, there was no cash-based economy, therefore Kings were forced to "pay" their knights in land, which the knights then lived off of. This causes a problem as the more land the king gives away, the poorer he becomes, and he has no way of collecting anything from the land he gave away. The knights can then use their land and power to usurp the king, causing instability and general problems which went on throughout the feudal period. As you had initially requested something "genuine" rather than "factually accurate", I outlined a cash-based feudal system below, which isn't entirely historically accurate. Further research into the issues of the feudal system might benefit you if you want it to be more historically accurate, but hopefully some aspects of my answer will still apply. **Responsibilities** Your lady's primary duty is to make sure that her people, whether they be villagers on the edge of her territory or villages closer to the center, are safe. In addition to physical threats like those listed in the last section, this may also entail watching for plague-bearers, monitoring trade caravans that come through her land, keeping an eye on the weather, and watching for stages of drought or blight. Vassals are given land to monitor because their Liege or King is too busy/rich/occupied to watch over every parcel of land. I liken it to [management in the corporate environment](http://www.hierarchystructure.com/business-staff-hierarchy/). Your King and his advisors are the Chairman and his Board of Directors. They demand that profits continue to rise, and that their positive reputation is maintained. In order to do that, each "department" or parcel of land must produce money, through taxes, tithes, or something similar. This job falls upon upper management, who must ensure each staff member (the peasants) is performing efficiently, paying rent, and farming as much as possible so they can be taxed. Her responsibility to her king or liege, therefore, is to pay him the profits of the land, whether that be in taxes or tithe, or "donations", and to report to him that everything is going well. Your lady can actually have as much or as little control as she pleases, but her goal is to maintain the population. Peasants have no ties to the land that they farm, so if a plague, blight, or poverty prevent them from working or surviving, they will begin to die off or will emigrate elsewhere. If she exerts too much control, demands too much in tithe, or on the other end of the spectrum, if she refuses to guard against attacks, or refuses to maintain certain things, she will find that her lands will be deserted, she will have no one to tax, and therefore no income. Ideally, she wants to establish a safe and stable economy. Responding to immediate physical threats quickly will show the peasantry that she cares for their welfare. Day to day she should open herself or her stewards to inquiries from the people. Do they need to dig an additional well in order to get more irrigation to crops? Do they need paved roads in order to transport their produce to the village to sell? These concerns must be weighed based on their costs. In this time there were no police, so she and her guards act as the judicial system, doling out justice, punishing criminals, and judging civil and criminal cases. Does she choose to judge each case herself, or are they too numerous, so she employs magistrates or guards to judge? She can use this as secondary income in the form of fines and reimbursement for these services, but may end up imprisoning some or forcing them to pay their fines with hard labor (this is a good way to get those paved roads without paying too much extra). Any problems that arise that cannot be solved by her, must be passed along to her "supervisor" to be handled. If her troops are not sufficient, she must call in the King's Army. If a blight destroyed her crops, she must request food. If a plague arrives, she must request medicine. These things are provided to her by her king because she pays her tithe and taxes, just as she provides these things to her people because they pay her tithe and taxes. If she has a poor fief or hasn't been paying enough/regularly, the king may ignore her requests and leave her to suffer. I hate to say it, but your vassal is essentially a Bookkeeper. She will spend most if not all of her days accounting in log books, or reporting to stewards who will record everything in log books. [Evidence shows](http://www.academia.edu/3502565/An_Essay_on_Accounting_History_Bookkeeping_in_the_Middle_Ages) that modern accounting was invented in the Middle Ages, and many of these log books give us the best view into how the feudal era and the Middle Ages ran. Day to day she must track everything, or she must employ people who track everything. How much produce is coming from the farms? Is it enough to keep some for winter? Can we sell some of it to neighboring fiefs for extra cash? Is the king making any special requests for produce (ie. is he having a birthday ball and needs 80 fresh geese?) How much income are the peasants making? Therefore, how much tax or tithe can she impose upon them? Do you demand a set sum of money each month/quarter/year or do you instead calculate a percentage of their funds? What if they can't pay? What if you usually demand a set sum but you notice a few peasants are making huge stacks of profit? Can you impose extra tax on them without them getting pissed off? Out of this initial tax and tithe you take out what cost she needs to maintain roads, wells, bridges, and whatever other infrastructure she needs. Then she will take out how much she needs to maintain her household. She will have troops that need to be paid, fed, and armored, servants that need to be paid, fed, and clothed, horses and whatever other animals she might want that need to be cared for, plus all those magistrates, stewards, accountants and whoever else she employs to keep the work from overwhelming her. Then her obligation must be made to her king or her liege. Whoever is next highest up in the food chain must be paid his/her taxes or tithe. This may be a percentage of profits or it may be x amount minimum, depending on the king's wishes. **Privileges** Only once her land, her people, her household, and her liege were "taken care of" in terms of taxes or tithe would she then get to take her "privilege". The remaining money would go to her own coffers to clothe, feed, or throw away on solid gold bathtubs as she sees fit. In addition to the money, she would be considered very trusted by the king. The privileges this could garner her are too numerous to list here, but she would have titles, meaning she would likely be able to marry nobility if she chose. She would be permitted into the palace, perhaps even become one of the King's advisors herself. **Obligations to Liege** Now, this is the ideal state of things, wherein the vassal is responsible and caring and doing the "right thing" by meeting her obligations. However, there is no law saying that she has to do anything except meet the obligations to her liege. He is the one with more power than her, and he can make her suffer. Like I said above, only the laws that can be enforced are considered true laws. So long as she can provide him with his tax or tithe, she can spend the rest of the money as she sees fit, like on the aforementioned gold bathtubs, and she can tax her people into oblivion so long as they don't die or abandon their lands. Again, it's all about how nice you want her to be. The accounts of corrupt lords are numerous, but it is important to note that she might be inviting anger from the king, a peasant revolt, or worse by these actions. In addition to the tax and tithe, the king may request extra produce or food (like for the aforementioned birthday gala), or he may request she send food to fiefs who are suffering from blight or drought. He may also summon her troops away from her lands if a national crisis occurs that requires more troops than he has in his standing army, and he can recruit her peasants as makeshift warriors if it is a truly huge war and he is desperate for soldiers. There is a ton more to be said, I would recommend looking at the links I shared, as well as looking into feudalism in general. There are a wealth of essays online, and like I mentioned above, we have a great view into feudalism, taxation, and other items like this because of the accounting work that went into this time period. [Take a look here](https://www.quora.com/Feudalism/What-are-the-most-common-ways-that-people-misunderstand-feudalism) for some common misconceptions about feudalism as well. [Answer] The normal duties of a feudal lord were upward. He owed a certain amount of military service to the king when called on. The land and its rents and incomes he ruled were the means to pay for the men and equipment he was required to produce on demand. A female lord might not be required to go to war herself, but still produce the men-at-arms under a male leader by the king. His duties downward are less clear. There are certainly anecdotes of nobles treating the commoners poorly. In a more general case you could at social aid as an ethical requirement, or a return on investment requirement (dead peasants produce no future rent). But to a feudal lord, the man reason for improving the fief is that the increase in income, so a wise lord might encourage towns, trade on his area in exchange for taxes, and add mills and other improvements that could improve the lot of the commoners. ]
[Question] [ I am playing with idea of Earth being attacked by aliens. Such attack is aimed on our computers and reason of attack is to show to the Federation of planets that we are still weak to be contacted. The question: **How would we handle after such attack?** * The attack is synchronised, covering all the Earth in one shot * Such shot sets all data stored in RAMs to all logical "1" * Also, hard drives are given instruction to write to all sectors logical "1" * Both instructions are on hardware level, so no check of write rights given. Assume the computer under attack will fulfil the request. * Assuming the aliens know our technology, the write process on HDD starts with OS sectors and then continues to "data" sectors. This applies also to SSD * Everything else than RAM and HDD/SSDs (namely tapes, DVDs and other "offline" backup systems) remains unharmed * To be absolutely clear, the attack also targets on routers and modems While the scope of attack is bit "magic", it obeys the laws of physics: * The attack is electromagnetic pulse based * So if a computer is hidden behind something which should prevent electromagnetic pulse, such computer remains fully functional * Also, the pulse obeys square inverse law, so the more mass is between orbit and the computer, the less effective the attack is. * My working meta is 10 metres of (any) mass between computer and orbit to render attack fully uneffective. * And, the attack is only one-off. No repeat of such attack. * Also, I am aware of one huge flaw: Computer has to be turned on in moment of attack. The attack has no effect on turned off computers. However, as long as the computer is at least in "sleep" mode, the attack has effect. I know I would not destroy **all** the computers, but I also know that I would be able to turn off more than 90% of all Earth computers. Addendum: Plot explanation: Imagine there is alien organisation called "Federation of Planets." They have FTL drives and actively seek other intelligent species to join them. In order to join, you have to pass a mark of setting foot on other planet than your own. There are "anti immigrant activists" who think, that the acceptance criteria should be raised to "visit other star system than own". These activist know, that "The Auditors" are going to visit Earth soon and check how advanced the Earth is. And they know that if we are unable to communicate, the Earth is not going to be accepted and next visit is going to happen in 50 years. So while the attack is mainly aimed on our communication, they decided to go over the top and attack us on whole scale. [Answer] Actually, while it would floor things for a while, I don't think it would even be close to long term effect. While not available to the masses, rolling back to 70's-80's tech would be achievable. Your EMP doesn't destroy data written to CDs (either mass-produced (printed) or rewritable (heat/melt phase change)) or on things like punch tape or punch cards. Punch tape could rebuild some 70's type tech which would give you micro controller firmware and so on, and from there something that could read CD ROMs. From the CD-ROMS you can get backups of OS source code and firmware for anything up to probably the 2005 time frame. There are probably enough people in the world adequately capable of writing straight machine code so they could program basics of firmware, BIOS and bootloaders from scratch. Because your weapon doesn't destroy the hardware, all it needs is re-initialising. There'd be some chaos, but if people were organised and had enough time (anything from a week to 3 months depending on how much chaos was going on - and remember old radios, old tvs, old cars and such don't need computerisation, nor do basic electric generators). Assuming an invasion didn't wipe us all out in the mean time, I'd say given a year everything would be sort of back to some sort of reasonable level. True, we've lost perhaps 10 years of data and tech, financial markets are a mess, no one knows who owes what, but eventually paper records get typed back in and even then not a 100% is lost. However, that's all assuming 100% currently electro magnetic storage is destroyed. If even a small percentage is unaffected, things return to normal much faster - it's just the time it takes to slowly rebuild section by section, but it's like the rice on the chess board, it starts off slowly, but as each fixed computer means someone can help fix a couple more, it quickly spreads across the world. There is currently a massive excess of backups, while not everything would get restored, I don't think we'd lose anything truly significant. [Answer] > > * Such shot sets all data stored in RAMs to all logical "1" > > > This would have the same practical effect as the power going out. Restart your computer and everything is fine. The big effect here would be on airplanes and so forth -- I imagine it's difficult to do a hard reset of all the electronics while the aircraft is in-flight. However, [this answer](https://aviation.stackexchange.com/questions/2072/is-rebooting-the-computer-normal-before-during-flights) suggests it is possible. > > * Also, hard drives are given instruction to write to all sectors logical "1" > > > This would have a much larger effect, since most data is stored on hard drives. Individuals would tend to lose everything (not many people keep backups), but corporations would just lose hours to days of data, and could quickly recover most everything. Because very little personal data is truly important, most people would be largely unaffected after a few days to weeks, since they could just recover the data from corporations who backed it up. > > * And they know that if we are unable to communicate, the Earth is not going to be accepted and next visit is going to happen in 50 years. > > > We can build radios out of random crap in your garage in like 10 minutes. This attack won't prevent communication with aliens in orbit. > > * While the scope of attack is bit "magic", it obeys the laws of physics: > > > No, it really doesn't. > > * The attack is electromagnetic pulse based > * So if a computer is hidden behind something which should prevent electromagnetic pulse, such computer remains fully functional > > > An EMP is indiscriminate. It will wipe out any and all electronics or none of them. The only question is how sensitive the given electronics are. So if the computer is partially shielded, the most sensitive components will tend to die while the least sensitive will tend to not die. The HDD platters are far from the most sensitive, and anything affecting HDD platters will also affect tape drives and other magnetic media. What you're thinking of is sending specific signals to a specific part of a hard drive's controller to make it think the OS told it to erase things. But you really can't do that. The normal radio photons are feet to miles across, so there's no way to make sure a photon hits a specific HDD controller, let alone a specific wire on that controller. Even wall-penetrating microwaves are several inches across. By the time you get to EM waves small enough to hit a target wire, we're talking ~~optical light~~ [EHF](https://en.wikipedia.org/wiki/Extremely_high_frequency)/[IR](https://en.wikipedia.org/wiki/Infrared) and beyond, which is easily blocked by walls, CPU cases, etc., and isn't readily absorbed into said wires. Now, sufficiently advanced aliens could hypothetically create an incredibly advanced interference pattern that cleverly hits specific points, even with large wavelength photons. However, this would require billions, if not billions of billions, of photons per bit sent. Because photons have fixed energy amounts, that means such an interference pattern would end up vaporizing everything around the computer, if not the entire planet (conservation of energy says even if there's destructive interference, the energy has to go *somewhere*). > > * Also, the pulse obeys square inverse law, so the more mass is between orbit and the computer, the less effective the attack is. > * The attack is synchronised, covering all the Earth in one shot > > > The inverse-square laws are about *distance*, not mass between you and the attacker. This means an attack from 100 km above the planet will have almost zero effect on objects on the other side of the planet (not including the massive planet in the way). Because everything is synchronized anyways, there are probably dozens to thousands of ships in orbit around the planet. The fewer ships, the further they have to be to get good spread. The more ships, the less distance there is between them. Either way, coverage will be relatively uniform, so the inverse-square law won't be a huge consideration. And the aliens are probably smart enough to concentrate the "bright" spots on the major cities. > > * My working meta is 10 metres of (any) mass between computer and orbit to render attack fully uneffective. > > > Mass between you and the attacker will exponentially decay signal strength, and the coefficient will greatly depend on the material in question, as well as the wavelength of the EM radiation used. The basic form is $I=I\_0e^{-\beta D}$ where $I\_0$ is intensity at the surface of the material, $D$ is depth into the surface, and $\beta$ is the coefficient for the wavelength and material in question. Air will have a very low $\beta$ value for most wavelengths, while concrete will have a high $\beta$ value for most wavelengths. Long wavelengths (low frequencies) will tend to have lower $\beta$ values than short wavelengths. > > * Also, I am aware of one huge flaw: Computer has to be turned on in moment of attack. The attack has no effect on turned off computers. However, as long as the computer is at least in "sleep" mode, the attack has effect. > > > This is only a problem if the attack somehow activates the "overwrite" circuits on the HDD controller. If it, realistically, just overloads the physical data structures, it will work on anything whether it's on or off. [Answer] Effects concerned (ability to communicate) would be very low. HOW IT COULD NOT SUCCEED: 1) It would not affect people. Professionals all around the world are keeping up with their respective fields more o less. Technology concerning, only latest research (5 years, 15 max) could be lost. Also keep in mind that research papers are usually literary kept as papers in university libraries. 2) if it would not affect turned off computers, technological impact would be even less. In all filed you have thousands of students caring their laptops filed with latest knowledge. chances that some of them would have their laptops turned off at time of attack are close to certainty. HOW IT COULD SUCCEED: 1) however, it would greatly impact out 'organization'. Databases of people, logistic databases etc. You would lose all kinds of data from lent books in library to who has access to security facilities. Everybody would know who is president without Wikipedia, but let's take Universities, you know don't know who are students, what marks they had, You would also lose most digital contracts, etc.. Minor a occasionally major social chaos would occur, and that could escalate into conflicts. 2) it would stop us for a while. Top scientist could not continue their researches further, but would need to focus on restoring our knowledge bases from their memories and fragments of surviving data. Put together with 1) it would mean we would be stuck for a while. SUMMARY: It has little to no chance to make us unable to communicate technologically, but it could realistically succeed by enduring chaos a making us unable to cooperate on answer. [Answer] Two parts to your question, the specified mode of attack and the effect on humanity. Let's talk about the effects first. Total breakdown of civilization in industrialized areas. Food isn't delivered to supermarkets, trains don't run, power grids fail. Civil defense might have contingency plans for any one failure, but they'll be overwhelmed. Non-industrialized areas might cope a little better, but they're not self-sufficient. Regarding the attack, you're getting overly specific for something which is magic ("all harddrives are ..."). Some notes: * The effect of overwriting RAM will conflict with the effect of overwriting harddrives. To do so you need working computers. What if someone pushes the reset button while the overwrite process is running? * You are talking about "inverse square" and "less effective", but the way you describe the attack there could be no partial effect. Either the harddrive controller is hijacked or not. * Even if people had offline backups, they'd have to restore the OS, application software, and data. Restoring the OS could run into problems with license codes/DRM. * How about computers that were switched off during the attack? Either cold backups, or personal computers shut down to save energy/cut the noise. [Answer] **Assuming that the electronics aren't completely fried, just "code-less" it won't take very long to bring everything back online.** An attack of this kind just makes computers into the human equivalent of comatose, not lobotomized. The OP doesn't mention anything about firmware being '1'-ed out so all the controllers in the hard drives will continue to work. Anyone who has offline storage media (flashdrives, CDs, DVDs) should be able to reinstall the OS and applications. **Big Business** How large information economy organizations come back online will depend on their specific disaster recovery solutions. Many will discovery significant problems in their strategy and it will take weeks to months for them to come back online. Large quantities of operational data will have been lost. **Basically, the First World economy stops for a while** as does the Third World. As long as basic food, water and shelter services can remain online, we'll avoid the Apocalypse. The future of humanity will rest in the hands of those nerds who have kept offline OS install media for their desktops/laptops and servers. Installing an OS requires someone, somewhere to have a functional laptop to bootstrap the system restore functions of all the servers. Once news gets out that laptops, desktops and phones that were turned off a the time of the attack are still operational once they turn back on, any kind of electronics store or warehouse will be mobbed to recover functional electronics. The largest supply of depowered electronics are eletronics stores, so expect a large run on those stores. **Preparation for Next Time** Humanity, when they recover will make sure to have redundant offline compute power and rapid methods to system restoration if all online equipment gets '1'ed out. How this is done will depend on the organization in question. Some organizations with large amounts of online data may just take the hit and revert back to offline backups. Private individuals may make it a practice to keep offline OS install media for their phones or computers. The more frequently this kind of event happens, the more decrease in its effect on humanity. Computing and communications infrastructure works very hard to increase resiliency in the face of failure. As a failure mode becomes better known, actions are taken to prevent altogether or just greatly decrease the effects of that failure mode. ]
[Question] [ Something I'm working on involving human soldiers in the future- I'm trying to decide whether hand-held rail guns or gyrojet firearms would serve as better weaponry, which advantages/drawbacks one might have that the other would not. Which would have better penetrating power? Require less resources to make? Might there be more ways one could malfunction than the other? [Answer] Both are pretty bad choices for an infantry weapon. If for some reason you're choosing between these two, any variant you choose is bound to have an impact on your world to be viable. Let's start with the **gyrojet**. You don't have to worry much about the recoil, and the disadvantage of its projectile gaining maximum speed at 20m is negligible if you don't plan plenty of close quarters combat. However, ammo is expended by millions in small-scale conflicts and by billions in large/protracted wars. Its cost is substantial, nevermind the need to throw out billions of outdated bullets and to produce a billion of gyrojet rockets, just to sleep safe. And as gyrojet ammo is bound to cost much more than a comparable bullet (much worse effects on accuracy from imprecise machining), you'd have to find a problem for this solution. Why would it be better than a simple bullet? Probably, you're recoil-sensitive (zero or low gravity). Or you have to use larger calibers as a standard issue (14.5 equivalent or higher) because of, probably, abundance of well-protected targets. In other words, if enemy soldiers are that protected by their individual armor, that 5.45-.50 won't cut it because of reasons you'll have to invent (power armor of sorts or outright aliens), but your soldiers for some reasons can't endure the recoil without broken bones (no power armor). Handheld weapons in which projectiles are accelerated **electromagnetically** (let's not delve into differences between railguns, coilguns and such) are usually meant to accelerate a very small projectile (~2-3mm). You run into all sorts of problems (power supply, very powerful magnets to accelerate a pellet sufficiently over the course of a quite short barrel, heat sinks as you'll have 2-2.5 times of pellet's kinetic energy dispersed as waste heat, weight), you still get recoil, but you have an outstanding armor piercing capability. It doesn't give you much. Anti-tank rifles of WWI and WWII were a specialist's weapon, as to knock out a tank you have to know where to aim at. To make a general-issue weapon you have to find yourself a peculiar opponent, the one with a large portion of forces heavily uparmored, but vulnerable to armor penetration in at least half of an individual target surface. If for some reason you postulate superior accuracy of the railgun (1 MOA at 3-4km, to start, hypersound speeds required), you'd better make sure your individual soldier will be able to discern a target at that range (though most time the range of view will be drastically lower), so equip them with sophisticated detection and targeting equipment. While increasing typical firing distance may bring an interesting battlefield, it will be mostly static, if you don't bring in a really increased speed of an individual soldier. **All in all**, individual weapons save lifes of individual soldiers, take other individual soldiers' lifes, but attribute only to 1/4 of all casualties (your battlefield may vary). The lion's share of all losses is inflicted by artillery. If you're planning a proper military action, not just a skirmish, your soldiers' weapons are to be a part of the doctrine, meant to have their own place alongside with artillery, drones, attack planes and helicopters, tanks, APCs and IFVs. If for some reason the traditional bullets are ditched, everything else should've changed too. For the sake of the narrative I'd personally leave bullets for close-range (as a sidearm) and snipers and went all programmable explosion automatic grenade launchers. No ugly trenches this way, just action. [Answer] Neither technology is good enough to replace modern firearms in their current state. But, since this is a future scenario question, let's consider we add a few decades of technology to the underlying systems to see if either could reasonably get there. Gyrojet's big disadvantages are cost and weight of munitions. Bullet per bullet, they are just not as efficient as normal guns, so to make them king of the battle field, you need to make the bullets cheaper and increase the weapon's kill-shots per bullet. One thing that the industrial revolution has taught us is that the cost of complexity is mostly a one time problem that is eaten by developing your manufacturing process, after that, cost per unit is mostly just materials. If you were building gyrojet rounds by the billions, then you per bullet, they would only be a little more expensive than normal munitions. That said, gyrojets have one distinct advantage in the future that makes them way better than normal bullets that most people don't consider. A low acceleration. As much as this sounds like a disadvantage, weapons with low accelerations can pack on-board systems without breaking them when they are fired. Modern image recognition means a smart gun can already lock onto a target, but guided bullets could respond to follow a target's change in direction mid-flight, compensate for firing conditions that could not be detected at the moment of launch, home in on soft spots in a target's armor, avoid friendly fire, or even act as a smart swarm whereby a burst of bullets could sort it self so that a 12 round burst could land kill shots on a group of 12 separate targets with no 2 bullets being wasted on the same one. It also means that you can add various specialized payloads to gyrojets including explosive, incendiary, shape charge, and any future other payloads you want to explore. Coilgun's big disadvantages are the cost and weight of the weapon itself. Miniaturization will be pivotal, but there are more technological obstacles in making future coil guns than future Gyrojets. Coilguns need to manage heat, and the smaller and lighter you make it, the less dissipation surface and sequestering volume you have to do this in; so, even if you do make a reasonably small and powerful weapon, you'd need an added layer of complexity in heat management that may require a little bit of hand waving. They are also much harder to make rapid fire since you need to recharge the capacitors between shots. Also, coil guns aren't just more complex than other guns, they require a lot of rarer and more expensive materials for all those electromagnets and power systems; so, they will always cost more than the alternatives regardless of how much you mass produce them. This added cost is offset to a degree with cheaper munitions. As for mechanizing coilguns, its higher muzzle velocity makes on-board electronics less possible but also less necessary than on conventional projectiles since the time from launch to impact is so much shorter. By placing all of the electronics on the firearm, you save additional costs by not using disposable electronics systems on the munitions, but you also lose some versatility. A smart gun has to see it's target when you fire, but a smart bullet can be fired through a visual obstruction, then make decisions based on what it sees when it comes out the other side. Over-all, the gyrojets are probably the better weapon. Higher rate-of-fire, more options for smart systems, more options for payloads, and fewer engineering hurdles add up to not just a better weapon, but a lot of cool plot points for making your future tech feel more "futurish". One last reason to downvote coilguns is that by the time your tech reaches the ability to miniaturize power systems enough to make them into practical infantry weapons, you will basically have everything you need to make a wide variety of equally portable energy based weapons. An electrolaser has a whole different set of versatility that a coilgun can't compete with. It can be modulated to stun, kill, sweep for mines, EMP a vehicle, etc. So as an infantry weapon, the coilgun will be obsolete by the time it is practical to begin with. [Answer] Good Morning, You will have a lot more options for designing near future weaponry, if you don't try to force a decision between these two. Please think about changing the title to something like "Infantry weaponry for a near/distant future setting" if you want to attract great answers. I only looked inside this, because I'm a fan of EM-Weapons :) **What kind of weapon** At this very moment, I can think of three kinds of weapons, that may replace the small firearms used today: electromagnetic waves, electromagnetic accelerated Projectiles and maybe thermobaric guns. *EM-Waves* Waves contains laser and maser and... stuff. All kinds of weaponized em-waves. While you will not cut through steel like a hot knife through butter, but you will overheat parts, which will do damage pretty well (especial on "wet" targets like humans, or anything that may act weird when getting hot). With power-storage getting smaller and more powerful, its not unlikely that this will become a big player in future infantry weaponry. In theory a fine weapon, because under combat-circumstances you will hit what you aim for... while you may need to hit it for several seconds. Further, its hard to detect the shooter (but I'm afraid that you might get a path of ionized air if you surpass output-power of 100 Gigawatt; that might be visible). So... you need energy for these. Lots of. But when this is far future, you might expect weapon-grade diode-lasers, so this stuff could be easy to produce and maintain. Not so far future will back up to gas-pumped lasers, that usually leave some... unhealthy stuff when used. You need to dispose this. *Ferromagnetic Bullets* Then Weapons, that accelerate a bullet using magnetic forces. Two possibilities are widely known: Coil (Gaus) Gun and Rail Gun. First one use the magnetic fields created inside a coil (better: dozends of them) to accelerate some metal thingy, second one are two or more metal bars, that get powered with the same current (now I fail to explain this better, because I'm no native english speaker :( ), so the metal thingy will escape using the only way out: forward. The Rail-Gun does look like its more resistant and more easy to produce, but I do remember that they assume a Coil/Gauss Gun might reach a better muzzle velocity, if they can coordinate these coils in a proper manner. Point is, you need much electric energy. More than a laser-gun? Good question. And ammunition. That you need to carry around. Count in batteries for power and some kind of ammunition. Oh, have a look at the Mass Effect universe, where they deliver bullets by cutting pieces of metal off a cube right in the gun when pulling the trigger. And thanks to damage effect due to high velocity, you don't need big bullets. One thing people often do assume is that the projectile needs to be something that do react to magnetic forces. Nope. Well... you can do a magnet force push to everything, if your magnet is powerful enough (even isolators), but they could also sling a snowball (well... no, it would melt)... so they can sling everything that fit into a ferromagnetic sabot. Take this in account. But this has to get reloaded to old way. *Thermobaric* Does sound uncommon, doesn't it? No, that not these "spray out gas and enlight it", these things are called... damn... aerosol-bombs? Anyway, its pretty much like a power-projectile, but if I remember right, they don't use explosion / expanding gas, they do use heated / expanded gas. Does sound similar, seems to be much more relaxing for the barrel and may archive more muzzle velocity. And may lack the huge muzzle-flash. But for usage in infantry weapons? I head that this may find its way into artillery-pieces, that cannot afford a ship-size Generator for a rail-gun. Maybe we will see a comeback of the anti-tank gun using this technique, when electric power isn't free available, but a tank with ugly hard- and softkill systems for rockets need to be removed. *Gyrojet* To be honest, until now I didn't know there is something like this. Well, I remember stuff like this in the very first Perry Rhodan Story (they brought such stuff to the moon), but I thought it was something the authors used some imaginary stuff. So I'm short of information about this stuff... seriously, rocket-acceleration of bullets? They did this to artillery-shells back in WW2 as a form of range-extending. But these do offer extreme visibility, noise and maybe additional dangers for the own side. And thing about the cost for a single bullet, especially compared to the others. And imagine what happens if your bullet-fuel explode right in your pockets, because of... unexpected heat. **What else** *Environment* While the time is important, you should specify in what circumstances your weapons of choice should work. Space, low-pressure, common-pressure, hazardous atmospheres (thats a tricky one... High power Laser might detonate gas-constellations that are suspicious to explosion when confronted with a fire, but low-power ones might work), bad weather, dirt and snow and rain, underwater and so on. *Field of usage* You say, that this will be used by infantry-man... but what are they supposed to engage with these weapons? Don't think a Laser or hypervelocity railgun projectile is a super-tankkiller, when the tanks of this area where build to resist such threats. So.. well, hope this helps a bit. [Answer] I'd say I'm partial to the gyrojet, because it is the way cheaper option and would be a better weapon in my opinion to equip to hastily trained conscripts in time of war. It has alot of basic advantages over conventional firearms, and even gauss guns. **note:** I am going to call gauss guns coilguns in an attempt to distinguish them from railguns which could possibly injure the user due to the intense forces required to launch the projectile. **Advantages of a Gyrojet:** 1. It has very little recoil, at around a tenth of a conventional firearm firing .45ACP since the projectile does all the acceleration, meaning that aim is easier. Whereas a Gauss gun would more likely have slightly more due to the forces of the magnetic field on the gun frame. 2. It is extremely quiet making a fwoosh sound similar to the opening of a beverage can, instead of the loud bang of a conventional gun. A coilgun also doesn't make much noise either unless the capacitor discharge required for the high power levels is loud which is more than likely. 3. The crack noise of a round going supersonic happens farther away from the muzzle decreasing chance of detection, whereas the coilgun would make an extremely loud crack right at the muzzle. 4. The weapon is extremely light, with the average gyrojet pistol massing around 0.4kg since the gun itself does not need to withstand much of the pressure of the propellant, and can be made of light inexpensive alloys or even plastics. This means cheap manufacture and high portability unlike coilguns that require heavy batteries and coils and complex switching hardware. 5. Gyrojets also appear very non-threatening so a target unfamiliar with them could easily mistake them for a toy and underestimate your capability. Wheareas coilguns have a huge intimidation factor and would be confiscated in an instant. 6. Gyrojets have few moving parts and no need for extraction, ejection, or reciprocating bolt mechanisms which allow high fire rates, and ease of cleaning, repair, and manufacture. They can also be quickly produced in mass numbers from cheap stamped or die cast parts. Rifling is also not required. Whereas the coilguns require a delay between shots to charge up the capacitors, and while they do have few moving parts they require large amounts of electrical engineering knowlege to repair and maintain. 7. The rocket propellant is generally clean burning, meaning that hundreds of rounds can be fired with minimal cleaning required afterwards, and overheating is not much of an issue as the rocket accelerates quickly outside of the barrel, and the rocket exhaust vents most of the heat away with it. In comparison, coilguns have no mechanical wear, but the batteries, electrical components, and capacitors would have limited charge and discharge cycles and would wear out over time. They would also be very sensitive to things such as water damage, emp, and the like. 8. The flame of the rocket exhaust is only visible from behind, unless you have special infrared optics or the air is really humid and a condensation trail is left behind. However, while the coilgun may not have a muzzle flash the coil discharge would generate lots of heat also visible with infrared optics, and would require a complex cooling system to prevent melting of internal electronics. The exhaust of the gyrojet while still within the barrel, also isn't very damaging and is descrbed by users to be a warm wind. 9. The gyrojet gun is operable in almost any medium including space, air, or water. Wheareas a coilgun would need complex waterproofing to work underwater. 10. If the gyrojet rocket hits the target before it's propellant is spent, the 5000 degrees farenheit temperature the propellant reaches after it leaves the barrel could ignite or burn the target. The coilgun requires special ammo to achieve an incendiary effect. 11. The gyrojet also doesn't start losing velocity the instant it leaves the muzzle like coilguns and conventional firearms, the propellant will provide continous acceleration for a good portion of the projectile flight providing good ballistics. 12. The gyrojet gun also requires no internal lubrication since the moving parts are few and under little stress which would be important in environments like space where conventional lubricants would boil off. Coilguns also do not require lubricants, however the complex hassle of maintaining the complicated electronics negates whatever time is saved by not having to lubricate the gun. 13. Gyrojets are extremely tolerant of gunk and dirt amd are very, very, very hard to jam and will still fire immersed in water, covered in mud, or contaminated with debris. The rocket exhaust will also blow the majority of the contaminants out of the gun's barrel. A coilgun on the other hand requires meticulous cleaning of sensitive electronics, and dirt within the internals could interfere with whatever sensors are being used to activate the switching between coils. **Disadvantages of a Gyrojet:** 1. The rounds are in general much bigger and heavier than those of normal firearms, which would slightly limit your magazine capacity due to the need to store proellant in the bullet, but they pack a bigger punch overall. However in a coilgun the rounds can be much smaller than those of a normal firearm, however that advantage is offset by the need to carry a massive power storage system including both batteries and capacitors. 2. The ammunition of a gyrojet is generally more expensive than a normal bullet since the ammo is made of precision components to withstand the pressures and precise nozzle alignment is required for spin stabilization. However, this cost can eventually decrease once the rounds enter bulk production and newer manufacturing techniques are used. Also, once more energetic propellants are developed the rounds can be smaller with even higher velocity. The ammunition for coilguns is dirt cheap since it is simply metal slugs, however that advantage is again offset by the maintenance cost of the complex electronics and the periodical replacement of the batteries and capacitors. 3. The propellant used in the original gyrojets was slow burning and didn't get up to speed until it reached 9m meaning that at within that window of really close range it would have the poor stopping power of a .22lr, but then would accelerate to have performance dwarfing most conventional bullets. This issue however could be fixed with explosive rounds, or simply faster burning propellants. The coilguns have great performance at all ranges, but for the power they put out, they are simply too bulky, nowadays handheld coilguns made by hobyists are only powerful enough for small game, yet are very bulky. 4. The gyrojets also suffered from poor accuracy, but according to research which has come to light it was mostly from the poor quality control of the firm that designed them. And in the future the gyrojets could be used as smart bullets. Coilguns have some of the best accuracy of any projectile weapon, this is the only category where they hold clear advantage. In Conclusion, while coilguns do offer great performance, they have few clear advantages over gyrojets, and most of the issues with gyrojets have simple fixes, but they havent been implemented because, gyrojets have gained a bad reputation due to the shoddy build quality used to construct them and currently there is no market for them. Currently, reliable handheld coilguns that even match the performance of a firearm without unnecessary bulk are currently out of reach with todays technology due to issues with switching between coils and lack of good enough power storage. I strongly recommend gyrojets as the weapons for your book. For more information on gyrojets and their operation there is alot listed here: source: <http://www.projectrho.com/public_html/rocket/sidearmslug.php> ]
[Question] [ Imagine a world with a dead core, like Mars, but covered in water. This world has managed to hold on to its atmosphere and quite a bit of its water as well. I'm sure the prodigious life there would be grateful if the planet could also hold on to its magnetic field. This core has been dead for quite some time. In fact, enough time has passed for its surface terrain to be largely smoothed out from erosive processes like tropical downpours and waves. [![enter image description here](https://i.stack.imgur.com/srdBJ.jpg)](https://i.stack.imgur.com/srdBJ.jpg) We know that even on Mars, which has a mostly dead core that it still has localized magnetic fields. And Callisto has an induced magnetic field from Jupiter created by a subsurface ocean. So, **Can a world with a dead core still retain a respectable magnetic field?** [Answer] **Nope.** The planet needs to have fluid motion of its core in order to produce a magnetic field. The magnetic field is produced via motion in the [dynamo theory](https://en.wikipedia.org/wiki/Dynamo_theory). If the planet core is dead, as in solid, then it won't be generating a magnetic field. The only idea I could think of for the planet to have a magnetic field is if iron the core cooled in the presence of a very strong magnetic field. Then the core would be a permanent magnet. However, what could create such a field and how long it could be maintained are unknown to me. [Answer] ## Yes But it depends upon how you look at it. For terrestrial or rocky planets with iron cores, Samuel's answer is correct. However, there are other types of bodies for which this might not be true. ### Gas giants For gas giants, the metallic hydrogen at the core works as your conductive fluid and can maintain a strong magnetic field. Whether you consider this a world with a "dead core" is up to you. ### [Ice giants](https://en.wikipedia.org/wiki/Neptune#Magnetosphere) Ice giants cores are likely composed of silicates and metals. Its mantle is composed of various ices. Neither contribute to the generation of a magnetic field. However, these bodies do have strong magnetic fields. The mechanism for magnetic field generation isn't well understood but it is thought that a salty liquid water outer mantle works as the rotating conductive fluid and it generates the magnetic field. In this case, the core is dead, yet the planet still possesses a strong magnetic field. ### Ceres [![enter image description here](https://i.stack.imgur.com/IWwnd.jpg)](https://i.stack.imgur.com/IWwnd.jpg) Some think that Ceres' water ice layer may include a water liquid layer. In which case, a planet like this could generate a magnetic field like that of ice giants. Such a planet would contain a solid silicate - metal core, liquid water inner mantle, icy outer mantle, and rocky crust. [Answer] **Yes**, a planetary magnetosphere can be induced without a core being involved: <http://www.researchgate.net/publication/222736075_Induced_magnetospheres> The paper's abstract reads: > > Induced magnetospheres occur around planetary bodies that are electrically conducting or have substantial ionospheres, and are exposed to a time-varying external magnetic field. They can also occur where a flowing plasma encounters a mass-loading region in which ions are added to the flow. In this introduction to the subject we examine induced magnetospheres of the former type. The solar wind interaction with Venus is used to illustrate the induced magnetosphere that results from the solar wind interaction with an ionosphere. > > > ]
[Question] [ In my Series there is a zombie apocalypse that has fast zombies in it. They are equally if not weaker than the average man. The problem is that running zombies are bad for storytelling. So I'm asking how I can make running zombies seem like less of a threat? Preferably equal in danger to 2-3 slow zombies. Below are some requirements both for design and story; > > The characters will need to be able to survive the apocalypse without military aid. > > They need to be under constant threat. > > The zombies need to be capable of destroying walls and barricades in large numbers and still be manageable. > > They need to be dangerous enough that survivors have to question whether or not to go guns blazing. > > The survivors will be average people with average skills. > > The infection will cause hydrophobia, insanity, Congenital insensitivity to pain, cannibalism, hallucinations, and animilistic behaviors. > > > [Answer] Since the key differences with your Zombies and the "traditional" zombies is these are alive but have limited intellectual ability, then your survivors will need to be able to create deadly traps. Any sort of man trap, big game trap or powerful weapon will help your survivors prosper. Since the fast zombies will simply mindlessly run at food, a person could theoretically lure lots of zombies into a deep ditch that is between him and them. Filling the bottom with spikes or razor wire will make it more deadly, or alternatively you could fill the bottom with flammable fluid and incinerate them. Flame weapons should otherwise be avoided, a burning fast zombie will be a torch running through the landscape and probably spread fire until it falls over. Since digging a ditch will be very time and resource intensive, it will be a lot more effective for the survivors to lay razor wire fences, abitis or other field fortifications that can be made in a workshop and rapidly deployed (being thrown off the back of a truck, for example). Building a perimeter will be time intensive, so they should focus on a small perimeter at first, then gradually expand it for more farm land and so on. The effect when looking overhead would be a checkerboard of small perimeter fences butting against each other, which would have the added advantage of providing a series of defendable areas, even if one or more were to be breached. If the fast zombies are really as stupid as described, then weaponry could be a simple as bolt action rifles (you wouldn't have to lead the target or deal with a zig-zagging target trying to evade) or even a long boar spear (the zombie will impale itself 6' away from you but the cross piece will prevent the zombie from getting closer until it bleeds out). Polearms might also be acceptable, so long as you are proficient and lucky enough to prevent a zombie from getting "inside" your guard; yuou want to be far enough away that you don't get spaced with blood or infectious fluids. I would avoid swords (even longswords or katanas) or bayonetted rifles since this brings the zombie too close for comfort. A large calibre pistol (.45 ACP, .357 magnum or similar) would make a good secondary weapon *if you are proficient in its use*, otherwise a 12 gage shotgun loaded with 00 magnum shot will put down human sized targets at close range. Finally, living quarters should be elevated and have limited access, preferably something like a ladder or climbing rope that can be raised or lowered. Should the zombies manage to breach the perimeter, then a raised platform will give you a final refuge, and you can always reach down with pole arms or shoot down with weapons to clear the perimeter area. The key is having access to sufficient resources, enough people who are willing to form a cooperative work crew to build and man defences, and constant vigilance to prevent fast zombies from closing to running and striking distance. [Answer] If you have several types of zombies, perhaps your zombies have different levels of intelligence. "Fast zombies" are completely stupid - they see food, they respond by running straight to it. They are naturally fast so this strategy works for them. When the food is no longer in their sight, they are too dumb to remember they just saw it disappear behind that door - or too dumb to remember how to open a door. Depending on just how much less of a threat you want them to be will make them more dumb. "Slow zombies" cannot depend on overtaking people like the fast can, they are too slow due to physical impairment or whatever. The ones who figure out how to survive do so by being more intelligent. They can open doors, launch ambushes, and maybe even figure out weak points of structures. In my opinion, doing this actually makes one slow zombie equal in danger to 2-3 fast zombies, which might be too far, but you can either scale down slow zombie intelligence or scale up fast zombie intelligence depending on your needs. [Answer] To make your fast zombies an average-man manageable threat, make them legally blind. They can see and track moving objects but have difficulty differentiating motionless prey from the surrounding clutter. Enhance all of their other senses, so that the smell of an open wound or the sound of a loud breath negates the concealment of motionlessness. Running through a zombie crowd would be suicide, but standing totally still and controlling your fear would work until one of them bumped into you. [Answer] I ask a lot of questions in my answer not so you can answer me or give clarification, but so you have ideas and know what to think about when writing your story. Please don't disregard my answer for that alone. Anyhow... My first thought would be to make these faster zombies short-lived. If they are fast, this means that whatever made them zombies has avoided most of the muscular (and probably skeletal) system. Because the pathogen hasn't impacted their movement and metabolism as much as normal zombies, they burn more calories, are more active, and therefore go through more wear-and-tear than traditional zombies. A faster metabolism also means that these zombies need to consume more to maintain their energy. Naturally, this means they are more susceptible to starving, and would have to consume far more nutrients than a traditional zombie. And since they're zombies, perhaps whatever made them zombies also impacted their body's natural ability to analyze fat cells and the body randomly starts breaking down random pieces of flesh for energy (giving you an explanation if you wanted the traditional "bones showing through ripped jeans" look). You mentioned that the zombies are afraid of water. There are a couple variables you can play with here. For example, whether or not they're afraid of small amounts of water, like a liter, or if it requires a larger amount; if they're afraid of blood (more on this later), etc. There are other hazards that need to be considered as well, such as fear and damage from fire, sunlight, impact/puncture/slashing damage, sounds, general light, etc. So, blood. Zombies being afraid of blood opens up all sorts of possibilities. The first thing that came to mind was the potential of the survivors cutting themselves in order to release blood to scare away the zombies. This has all sorts of repercussions, like infection (especially to zombification), wasting of medical supplies, permanent physical damage preventing future escape or defense, psychological repercussions (and they, too, would eventually become numb to pain), etc. And do the zombies fear their own blood (if they have it), and if so, how does this affect feeding? Now, the others focused primarily on what makes these faster zombies weaker than traditional zombies. But first we have to decide what makes them *stronger*, as well as what makes zombies strong in the first place. Zombies often have strength in numbers. Hordes, mobs, gangs--whatever you want to call them--of zombies are much harder to defend against than a single or a handful of zombies. This pack mentality is a strength in that they know to gang up on survivors, but is also a weakness since these zombies fail to analyze their environment or formulate any other "strategy". Against hordes, limitations are mostly limited to marksmanship, ammo, strength/energy, fatigue and means of escape. A fast horde merely makes all these factors more important. Next I want to talk about durability. Exactly how much damage will your zombies be able to sustain before showing signs of weakening and eventually defeat? Will a headshot limit their motor abilities (or even kill them), will damage to any part of the body limit its use, and how much can they heal after "battle"? That last one is a big one I don't think many consider. Strategically, how much of their resources will the survivors put in to defeating zombies they meet in order to prevent them from coming back to get them? And if the zombies survive, will they be able to tell other zombies the survivors' location? (like how ants and bees can alert others)? Now, processing and computational ability. Just how much can zombies learn, analyze, perceive, process, etc.? Can they measure danger, and retreat to save their own lives? Do they even have instincts to survive, and if so, how much (and why would they go after humans if it means certain or a high chance of defeat (if they can think that much)? Before I mentioned a pack mentality, and psychology is a far overlooked element in zombie literature and media. Do they require others to process information and make decisions? Are there alpha males and beta females? Are there even genders? Is there a hive mind, or does the pathogen give them new instincts to go on? Do they have families, friends, relations, etc.? These can all cause strife on their own. Examples: a renegade from the hive, conflict for the position of alpha male, political events and political power, alliances/factions, etc. How is the virus spread? Is it airborne, intravenous? Does it use living vectors, like plants, natural bacteria (like the ones we have on our skin; this a big one, because if so, there's not much way to avoid it for long), or through asymptomatic/immune carriers (like a seemingly uninfected bird or dog)? Are they afraid of water because the pathogen can't spread over water? You mentioned various kinds of strains, and I would like you help you improve upon that. Assuming you know how the pathogen can spread, what if there were certain forms of zombies that acted like infantry and ran only to spread the virus (like suicide bio-bombers)? Plants and fungi are crucial topics. Can they spread through root systems and mutate the plants, creating spores or poison? Can they sense and communicate through plants? If you want fast zombies, perhaps they're just animal versions of these zombies. If the virus can affect multiple species, you could just have different variants that depend on the species, like air-bombing birds and espionage squirrels. That also brings up the topic of pets. A pet is another mouth to feed, and one requiring special food, but have superior abilities. They can alert the survivors to zombies using their superior senses. Birds can deliver messages (if they've traveled a route previously and are trained) and can do "reconnaissance". Dogs can attack as well as scavenge for food, as can cats. Perhaps reptiles and amphibians are immune to the virus (antidote, anyone?). Pets can also provide psychological support, which is direly needed in a situation as damaging as this. Remember, power is not just in destructive capability but in all results that can be achieved. I might add a little more after submitting, since this was a very long-winded answer. But I had a ton of fun writing it, so thanks! ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 8 years ago. [Improve this question](/posts/18269/edit) Assuming some magic handwavium caused the sun to go supernova, how long would it take to reach Earth and wipe out the planet? I know it would be eight minutes until the light reached us, but how fast would the physical explosion travel? [Answer] Using the physicists rule of thumb that *"However big you **think** supernovae are, they're bigger than that."* **[A supernova detonated 1 AU from you is $ 9 $ orders of magnitude brighter than a hydrogen bomb detonated against your eyeball.](https://10minuteastronomy.wordpress.com/2013/11/28/a-hydrogen-bomb-detonated-against-your-eyeball/)** Here's a nice video of a [Type 1a supernova explosion.](https://www.youtube.com/watch?v=9BPxc5-9M-4) **Why wait?** The Earth's destruction doesn't need to wait for the "physical explosion". Just the electromagnetic radiation from the supernova will do the job handily. **How much time do we have?** From the Physics stack exchange, I find: * [A supernova delivers $ 2.0 \times 10^{16}\ \mathrm{\frac {J}{s\cdot m^2}} $ at 1 au](https://physics.stackexchange.com/questions/25674/how-much-energy-does-a-super-nova-generate) * The Earth's radius is ~ $ 6.375 \times 10^6\ \mathrm m $ so its cross section ~ $ 1.3 \times 10^{14}\ \mathrm m^2 $. * The Earth intercepts $ 1.3 \times 10^{14} \mathrm{m^2 \times 2.0 \times 10^{16}\ \frac {J}{s\cdot m^2} = 2.55 \times 10^{30} \frac {J}{s} }$ of energy * [It takes $ 1.2 \times 10^7 \mathrm{\ \frac {J}{kg}} $ to vaporize silicate rock.](https://www.coursehero.com/file/p4ahg28/Silicate-it-takes-12-MJ-kg-to-vaporize-silicate-rock-So-the-energykg-available/) * The Earth's mass is $ 6.5 \times 10^{24}\ \mathrm{kg} $ * Energy to vaporize the Earth is $ \mathrm{6.5 \times 10^{24}\ kg \times 1.2 \times 10^7\ \frac {J}{kg} = 7.8 \times 10^{31}\ J }$ * Time it takes to vaporize the Earth is $ \mathrm{\frac {7.8 \times 10^{31}\ J}{2.55 \times 10^{30}\ \frac {J}{s}} = 30 s }$ **30 seconds from the radiation front reaching Earth until the Earth has absorbed enough energy to vaporize.** **How much time, really?** In response to some comments, I dug up a little research from "What If". Even if you were on the side of the Earth away from the explosion, you wouldn't get the extra 30 s (or more) it took for the supernova to vaporize and disperse the Earth. It turns out that [at 1 AU, the supernova puts out a lethal dose of neutrinos](https://what-if.xkcd.com/73/) and the Earth provides no protection. Since neutrinos travel at >0.999976c, you really only get **less than 0.012 seconds** before you received a lethal dose. I estimate the dosage at ~23 grays of radiation. Which [On this table](http://www.projectrho.com/public_html/rocket/radiation.php#id--Effects_of_Radiation--Acute_Radiation_Syndrome_Chart) indicates the following: > > Immediate disorientation and coma will result, onset is within seconds > to minutes. > > > Prognosis: **Certain death** > > > But the neutrino front does **NOT** possess enough energy to destroy the Earth, just enough to sterilize it. [Answer] Which type of supernova? There are several: ## Type Ia A [white dwarf](http://en.wikipedia.org/wiki/White_dwarf) is a type of compact star composed of electron-degenerate matter, and is the endpoint in the evolution of most stars in the universe (including the Sun). No fusion occurs in a white dwarf: its luminosity comes entirely from stored thermal energy. If a large ($1.3-1.4~M\_\odot$) white dwarf occurs in a binary system and accretes matter from its companion, it can eventually become heavy enough to begin carbon and oxygen fusion. The extreme density of the star means that the fusion 'flame front' takes a little more than one second to propagate through the star, releasing a huge amount of energy as it does so: enough to unbind the star, resulting in a supernova. The mass at which a type Ia supernova occurs is pretty much an invariant. This makes type Ia supernovae useful as [standard candles](http://en.wikipedia.org/wiki/Cosmic_distance_ladder#Standard_candles), and also means that we can quote (relativly) precise statistics on their products: * Ejecta: $1.4~M\_\odot~@~6\%~c$ * Energy release: $<2\cdot 10^{44}~\text{J}$ * Luminosity: $\approx 5\cdot 10^{9}~L\_\odot$ So if the Earth somehow stuck around until after the Sun's red giant phase, *and* the mass of the Sun was increased around 40%, the ejecta would take around: $$ \frac{1~\text{AU}}{6\%~c}\approx 2~\text{hours}~20~\text{minutes} $$ to reach us. The supernova doesn't reach full luminosity immediately, since most of its energy is trapped inside the dense, opaque, expanding outer layers. It takes around two weeks for the star to become optically thin, when peak luminosity is reached. However, the initial luminosity is still high enough to vaporize the sunward side of the Earth, and to sterilize the night side of the Earth via reflected Moonlight (if you're close to a full Moon). ## Type II/Ib/Ic These are *core collapse* supernova (the type discussed in [the What-If article](https://what-if.xkcd.com/73/) mentioned many times in the comments), and only happen to stars large enough to burn silicon, producing iron in their cores. The lower limit is around $8~M\_\odot$, making it impossible for a core-collapse to occur in the Sun unless two things happen: * You increase the mass of the Sun by 40% to the [Chandrasekhar limit](http://en.wikipedia.org/wiki/Chandrasekhar_limit) * You convert the entire (increased) mass of the Sun into iron. This would result in some sort of weird fully-stripped core-collapse supernova which could not occur in nature. Usually core-collapse supernovae blow off most of their mass, leaving a neutron star remnant behind. In this case, some of the core would be expelled, and I don't know if a remnant would form. In either case, we'd be hit with an Earth-vaporizing dose of gamma rays from the unobscured photodisintegration before the fatal dose of neutrino radiation reached us microseconds later. ]
[Question] [ Let me set the scene: A team of scientists in their lab one day is told that some miners have discovered some strange new substance. Its properties are extremely peculiar, unlike anything ever before seen. Most of those properties are fantastical and inexplicable (think 'Pure', judgmental energy that seems to only provide when you beg it to enough). How would they react, or present it to the scientific community? PS: Is this science based? I don't particularly think so, but I don't know what to tag it. [Answer] Typical scientific process when discovering something that doesn't agreed with accepted models of nature: 1. Make sure it's not a fluke. 2. *Really* make sure it's not a fluke. 3. Perform quantitative tests. 4. Get others to check your results (credit to @Burki for the peer-review suggestion). 5. Form a succinct explanation of what's going on. Testing: *When you beg of it enough* is a qualitative answer. It doesn't provide any measured figure about any of its properties. Once scientists are sure this is *something* new, they'll will try to gauge its properties. * Mapping exactly how hard a person has to beg, to gain a certain result. * Does this effect scale with the number of people begging (begging for the same thing, and for different things). Before they talk to their own community, or the public, they'll want to make sure they have their proverbial ducks in a line. Making fantastic claims like this would end your career if it was found to be something fake or easily explainable. Read [this article](http://nautil.us/issue/24/error/the-data-that-threatened-to-break-physics). It's about a recent incident in the physics community where someone detected particles travelling faster than the speed of light. It's rather long, but it gives a great insight into how cautious scientists are. They made their discovery, knew exactly it was either **revolutionary** or flawed - and spent *months* doing further research in *secret* to disprove their own discovery. In the end it was just flawed data. [Answer] ## Questions would be asked Scientists are intelligent human beings, not stimulus response machines. As such there would be intelligent discussion about the thing. Questions would be asked, such as: 1. How can the stone know that it is being beseeched. 2. Is the stone aware of us? 3. Is the stone intelligent? 4. Is this some sort of strange quantum thing? 5. Is the stone alien? 6. Is it dangerous? Can it hurt us? 7. Can we ask it for gold, money, cure for cancer, etc? 8. What are the limits of it's power? 9. Should we tell anyone about this? 10. Should we use this power? 11. Are we gods now? ## Not part of any known pattern Science proceeds by attempting to fit information into known patterns, extending the body of knowledge. It would be immediately obvious that this was something so far outside the norm that is should be treated with great care. There would not be an obvious way to investigate it because it doesn't form a part of any known pattern. ## Investigation The scientists would want to come up with ways to approach the problem. I would anticipate attempts to duplicate the wish granting behaviour. I would also anticipate an attempt to remove a small chip from the stone for analysis. ## Publicity Successful experiments would be filmed. I would expect these films to be put on youtube and go viral very quickly. I would expect great interest from all corners of the scientific community. If the rock can indeed grant wishes I would expect great interest from the Pentagon / relevant governing authorities and accompanying security. ]
[Question] [ In 1495 European sailors discover america, and found the nasty surprise that dinosaurs had survived in this continent and are the dominant species. Can an early arquebus kill or damage a large carnivore as a T-rex? [Answer] The caliber of an arquebus could vary pretty widely but would typically fall somewhere between .69 to .80, had a muzzle velocity of around 1351 fps, and had a smooth bore. To offer a comparison a modern 12 gauge shot gun is about a .748 caliber, 1800 fps, and also a smooth bore. So to generalize an arquebus is a bit like a slow loading, less accurate, and slightly less powerful shotgun... Keep in mind that a 12 gauge slug is pretty formidable and you could probably get a slightly better comparison by looking at reduced recoil shells. [Here's a video with some pretty good ballistic gel analysis.](https://youtu.be/7HuVkXLreWE) You're likely to see a foot or more of penetration with a rather large residual cavity. So what does this all mean for you? Well, in a volley of fire formation which was typical for the arquebus, shooting at a t-Rex you're likely to strike it a few times. Each hit will likely mean a fairly deep traumatic wound and if nothing else some significant blood loss. Would it stop a t-Rex charging toward you at 30mph? Probably not. Would it eventually bleed out, or die from internal injuries? Probably. Would it kill you before it bled out? Most likely. What hope is there? [Use cannons as well.](http://en.wikipedia.org/wiki/Cannon) [Answer] There were guns that ivory hunters used that could take down elephants, but they had to hit them in the heart because anywhere else wouldn't kill them, and they wouldn't penetrate the elephant's skull. I guess if you found a weak spot then the same/similar gun could be used to kill a T-rex, but they're obviously a lot bigger. Maybe if you sneaked up on it or distracted it and managed to shoot its Achilles tendon (no idea if dinosaurs have those, but if not then something similar) so that it would be unable to stand, then you could get another shot off into the heart once it's lay on the floor. [Answer] A lot depends on the dinosaur you are shooting. If they are the monsters most people associate with dinosaurs (T-rex, giant sauropods, ceratopsidae like the Triceratops etc.) then your best bet is to either stand very still or run very fast. If a Velociraptor pack sights you, then all bets are off. The slow loading speed and limited power and accuracy of the firearms of the 1400's also means that you will have a difficult time trying to deal with many of the smaller dinosaurs, which would be very fast moving (with T-rex as the apex predator, they better be) and extremely hard to hit. In many cases, the crossbowmen might have a better chance of hitting the smaller dinosaurs, and a big crossbow quarrel would do considerable damage as well. If you can land enough people in North America, then the military technology of the time *might* offer some help. Large formations like a *Tercio* use masses of pikes to protect the firearm wielding soldiers while they reload, and a bristling pike square might deter most of the lesser carnosaurs. If you can wait for the 1600's, Gustave Adolphus can come to the rescue with lightweight cannon that can move with mobile formations in the field, evening out the odds a bit more (and the musketry will also be somewhat more effective as well. Individual soldiers in the 1400's could also be armed with various sorts of pole arms, which provided enough reach and leverage to crack open an armoured knight; this would also give them a chance against many types of dinosaur as well. Mounted knights probably won't do well (the horses would shy from the dinosaurs, and predators would simply see a mounted knight as lunch), but dismounted men at arms with full armour and pole arms or maybe a 2 handed sword would have protection and an effective weapon. Working with a formation of pikemen, arquebusers and crossbowmen, you would have a fighting chance in a dinosaur environment. I did not include longbows since they were very specialized and only a very small number of Europeans were proficient with their use, mostly because the Welsh and English trained for a lifetime to use them effectively. Henry V could probably use his army of 5000 bowmen backed by men at arms to fend off dinosaurs until the arrows ran out. Even modern firearms would be iffy, although the accuracy and firing sped would be vastly improved, you are still dealing with rather large targets which will need multiple hits (especially with smaller calibre firearms). When you go dinosaur hunting, you probably want a .416 Weatherby Magnum or a Barrett Light .50 instead. ]
[Question] [ I know the question is rather broad but I hope to find a somewhat general solution. Here is a sample scenario: Two characters are in a room. One of them starts discussing something private, the other says "Shh, don't you know the walls have ears?" signifying that they could be under surveillance. How can they communicate in relative safety? Here are my assumptions so far: * the setting is of oppressive almost constant surveillance, akin to George Orwell *1984* * the surveillance could be mystical or high tech or simply just guys listening and watching. The exact nature doesn't matter as much, the characters possess similar means. But it's not a matter of hopping to the local supermarket and getting an anti-surveillance kit. * the characters also do not possess any abnormal means of defeating the spying, for example they won't have telepathic communication super secret wireless communication devices embedded in their skulls if these don't exist in the world. * the observation is not absolute. However, the characters do not know what is monitored and how. It can be assumed that simply passing notes is not automatically safe (*they* could be watching, not just listening) but it could be that it *is* safe in, some environments. Going by *1984* again, Winston's methods may have succeeded, not just ruled out to be completely subverted. * the characters need not necessarily know each other, so they don't have an pre-established code or cipher or something. They can certainly do this as things progress but it shouldn't be a given. So, I am looking for how would the characters go about establishing any number of these things * *where* is safe or not - if they could at least be fairly sure about either, they might find places to communicate * *what* the nature of the surveillance is - audio, visual, both, maybe others kinds, like wiretaps, or invisible spirits watching a room. * *how to subvert it* - **would probably rely on the above first** as the characters would need to work out a scheme of communication without being spied on. Unless there is a safe way to communicate without establishing the method of communication first. The characters could use ciphers or encryption but note that these could be cracked or compromised, if they establish what the scheme is in a non-safe place. Ideally, I would want the characters to be able to communicate face to face (or at least being in the same place) in some way. I am interested in how people would go about understanding the limits of prevailing surveillance without too much risk to themselves. [Answer] If you go to the Information Security Exchange you will see over and over again: ``` There is no such thing as perfect security. ``` An adversary with sufficient desire and means will compromise your communication pathway. That is what makes 1984 (and real life big brother states like China) so frightening. These big brother states are limited by their ability to filter out the normal from the interesting. During the Vietnam War, American POWs were isolated from each other in order to wear them down. The POWs began communicating using everyday sounds. Since everyone in the Hanoi Hilton was sick, the POWs would cough and sneeze in code to pass messages. Chores became means of communicating - the delay between sweeps on a broom could be varied to produce Morse code. These methods are not fool proof, but they were sufficient for the POWs. A more aggressive "big brother" would have certainly understood every message passed, but the North Vietnamese were distracted by the whole fighting a war thing: they could only devoted so much manpower / time / energy to the POW camp. So the key to your story will be three-fold: 1) What is normal behavior? 2) How can I modify that behavior to pass information? 3) (most importantly) What limits Big Brother? - with unlimited time and money nothing is secret. [Answer] There are two ways to beat this sort of system. **Firstly from without:** Essentially you need to be able to hide the message in among seemingly innocent interactions. For example I read a sci-fi novel where an undercover agent always went and had sex with the same person whenever he got back into port. What wasn't known to the local authorities is that they were both agents and they had a language that could be "spoken" between them by applying various levels of pressure with various parts of their hands while they seemed to be paying attention to other matters. The example in another answer of inserting key words into phrases is also a good example, as is using pauses between words. The key thing is to bury your communications inside something unrelated so that people do not see anything untoward either at the time or later on replaying the surveillance. You should also make a habit of going and having similar conversations without any hidden meaning to all sorts of other people. This means that if one person is uncovered then it becomes much harder to work out who out of all their contacts is actually a contact. **Secondly from within:** Get people inside the system and they can work out where is monitored and where is not, knowledge of those black spots can then be distributed to others and information slowly spreads as more people are recruited. The weakest point in most systems are the humans running it, not the systems themselves. Subvert the people and you subvert the system. **Combined approach** Perhaps the best solution would be the combined approach. Insiders provide some privacy in one area which is then used to develop codes and other methods that allow you to communicate even while under surveillance. [Answer] Sign language? Can't be overheard, and you can use your body to block your communications so they can't be seen. (You can *whisper* to someone in sign by making your signs really small so that only they can see). Alternatively, morse code using touch. Morse code already exists, you wouldn't have to spend too much time developing it. You might not even have to ever broach the idea of using it out loud - everyone knows SOS. if someone starting tapping that on my knee in an orwellian world i would go out and learn the rest of morse code to find out what else they had to say. Light taps can be easily obscured by clothes/blankets/screens. I think there would be an element of risk no matter what system you choose. The consciousness of this risk can only improve your story by adding tension. [Answer] In that environment I would just assume that I am always under visual/audio surveillance 100% of the time. Anything I read or write will be read by the bad guys. The best form of communication would be something that you can do in plain sight in front of your observers. One TV show had a bit where two stage magicians communicated using Morse code with the length of the spaces between spoken words. It's clever, but if the bad guys play back a video recording there's a chance they could pick up on this. If your two people have a safe way to make arrangements prior to being under surveillance, they could set up a set of [One-Time Pad](http://en.wikipedia.org/wiki/One-time_pad)s. Rather than going through the math described in the Wikipedia article, I'd just memorize a simple lookup table such as * fish: get me out of this place! * wrench: I need more time * potato: I need more stuff/tools * ring: I need more people * sock: I quit, this is too complicated. The interesting bit is that you don't get to reuse the table. You must have a new one with completely different (& totally random) key words for every communication. Anyone listening to your conversation might not even notice that you're sending secret messages. If they do notice, how are they going to figure out what "fish" means, when in the next message you might use the word "carbon" to say the same thing and you never re-use the word "fish"? [Answer] I'll give 5 levels of tech,and how to manage 1. Inside Man:just be 45ft or more away from any unfamiliar ppl lol 2. Spy drone: a backpack with a strong neodymium magnet,with a tethered copper wire harpoon. Shooting the drone disables it 3. Smart City: Go as far as possible from any civilization 4. Satellite Monitoring: Same as 3,but also in a cave or other enviroments that block aerial view 5. Neuralink Tracking: you are not safe,conform ]
[Question] [ Actually this is not an idea for a book, I thought about it after reading this [article](https://spectrum.ieee.org/moon-base). The power grid they propose for the moon would require a lot of electric cables and robots that bring power where the cables do not arrive. But even if the moon is smaller than the Earth a not too small range of operations would require distances in the order of thousands of kilometres. It would take a long time and a lot of resources to set up such a network. I have in mind a completely different type of grid. The Moon in any case is not going to be as crowded as the Earth, if there were microwave beams crossing around they would have little interference, this is one of the few cases where wireless energy transmission would make sense. For the first period there could be different photovoltaic plants placed in such a way that at least one of them is in full sun light. Then the plant that is working transmits a microwave beam to a satellite in orbit that relays it to second satellite and then to a base on the side where it is night time. Each base acts as a recharging station for all the robots that work in the area. Wouldn't it make more sense than a cable carrier robot based version? [Answer] *While taking an economics course in college, we were divided into groups and asked to write a decision paper explaining our choice for how to dry one's hands in a bathroom to executive management. That experiment was enlightening. Without taking serious time to think things through, you're almost guaranteed to come up with the wrong answer.* **Where are you getting your resources?** In a comment you surmised that: > > panels built on the Moon, even if with lower quality and lower efficiency would be way cheaper. > > > That's not true. That's not true at all. Consider this chart: [![enter image description here](https://i.stack.imgur.com/8dTNL.png)](https://i.stack.imgur.com/8dTNL.png) *Source: [NASA](https://www.nasa.gov/sites/default/files/atoms/files/significant_lunar_minerals.pdf)* What that chart tells you is that most of the minerals you need are "minor" or "trace" elements. If you open the linked document, you'll learn that "minor" minerals comprise less than 5% of available material and "trace" less than 0.1%. So... 1. You'll need significant mining assets to acquire useful minerals on the Moon. 2. You'll need smelting assets to process those minerals. 3. You'll need manufacturing assets to produce your panels. 4. And for all of that you'll need people, food, administration/medical/security/etc.... Manufacturing almost anything on the Moon will be considerably more expensive than manufacturing it on Earth and shipping it. Notably because shipping doesn't require crewed flight and could be reasonably based on the belief that if you have as much infrastructure on the Moon as you suggest, then the Earth already has a cost effective solution for bringing materials to orbit. Further, efficiency in a harsh environment *is a big deal.* Even if it were cheaper to build a less-efficient lower-quality panel on the Moon, the increased cost of operations due to increased redundancy, maintenance, and replacement could (and likely would) entirely negate the value. **What costs more: inefficient power beaming or laying cables?** There's a reason why hundreds of millions of miles of Internet cable have been laid in the U.S. The cost of laying cable here is lower than the cost of setting everyone up on wireless. That's changing over time, but only after technology has improved the stability, throughput, security, and traffic-handling abilities of wireless solutions. You're running into the same problem. Satellites? Never. Way too expensive to build, place, and maintain with much to low efficiency. Beamed power (e.g. lasers?) Possibly, but every time you convert from one form of energy to another (e.g., electrical to photonic), you lose something. Then there's no such thing as perfect optics, and the laser must hit dead on your target, so little to no mobile power solutions using focused beam technologies. Just to make a point: wireless charging is still a novelty here because it's too expensive with too little benefit. **Conclusion** Keep It Simple! Unless the industrialization of the Moon occurs at such a late date that Clarkean Magic can be invoked, the cheapest solution will... * be the most power efficient, * require the least maintenance, * enjoy the longest Mean Time Between Failures. Because transport costs occur only once and, I sincerely believe, will always be cheaper than mining limited minerals on the moon, smelting them, manufacturing goods, and hoping you don't need a lot of people to do that. (I know what you're thinking... *automated equipment.* O'course, by the time you shipped all that automated equipment up there you could have shipped your entire power grid and been up and running.) In an environment that doesn't have access to abundant atmospheric oxygen and industrially available hydrocarbons, it's going to be very hard to beat wires, transformers, and lithium batteries. (And lithium isn't found on the list of minerals available on the moon... Neither is copper and a large number of minerals we use today.) *Success is benefited by technology, but it wholly depends on economics.* [Answer] ## Just store the power. No, you do not want to use a bunch of expensive batteries when storing 15 days worth of power at industrial scales. What you want to do is store your power at an very large scale. Here on Earth, the best storage technique for large volumes of energy is hydro-pumping. On the moon, using a hydro-pumping station (but with Regolith instead of water) would probably still be cheaper than the wire around the moon or the microwave transmission method, but the moon is a very different environment than the Earth. It has less gravity, and much more extreme day/night cycles than we have here on Earth which not only reduces the effectiveness of some options, but opens up some new ones as well. I've done the math on a few things under Moon Conditions, and the winner appears to actually be a method that is grossly impractical on Earth, but pretty reasonable on the Moon. Let's start off by creating a more discrete scenario so that we can talk in real numbers. The OP can adjust as needed for his setting. Let's assume you have 2 bases that each have a power need similar to a small town: about 10 megawatts. Producing 10 megawatts of power on the moon (during the day) takes about 100 tons of solar panels, plus about another 100 tons of supplemental hardware. If we assume you are transporting these from earth using current technology, that is about a 2.4 billion dollar investment... however, once space flight becomes a mass produced service, this number could drop to as little as 40 million dollars per base. You should assume we are talking an ideally cheap space program is in place before largescale colonization happens; so, it is probably a safe bet that your total solar powerplant cost (before you solve the night time problem) will be closer to 80 million dollars than 2.4 billion, but anywhere in this range is plausible. Now let's take a look at our contenders: ### Microwave Transmission Microwave transmitted power loses a lot of efficiency each time you relay it. Even in a perfect vacuum, at relatively short ranges, you would be lucky to achieve more than 45% efficiency per transaction. If we assume your transmitters can perfectly focus the microwaves over thousands of km, you are still looking at a 3 stage relay system resulting in only 9% efficiency. However, in practice, those long distances will matter a lot and actual efficiency will probably be less than 1%. This means that even in a highly idealized scenario, you'd need over 10x as many solar panels to power the dark side of the moon as the day side using microwave transmission. So before you even factor in the cost of the transmitters and satellites, you are looking at at a 900 million dollar price tag in solar power plants alone... again this is super idealized. Using current technology, it would be somewhere in the hundreds of billions of dollars, maybe even in the lower trillions. ### Using long-range wires As for wires: Transmitting power through a wire loses voltage over distance, and the longer you want to go, the thicker you need to make it to reduce resistance. Running 64 amps of DC at 155,000 volts means that running a 1000kcmil wire would result in a 28% power lose, plus you'd have additional 10% loses at the destination when you try to invert that power down to a usable amperage resulting in a 72% efficient system... pretty standard for long-distance high voltage wires... but this is a very thick and expensive wire for so little power. A wire this size costs about ~530 million dollars and weighs about 26 tons. This adds ~310 million dollars under current lunar shipping costs, and only a few million under idealized future costs; so, if your future world has really cheap shipping, the cost of this much copper wire actually becomes a much bigger concern than the cost of sending it to space. That puts this solution somewhere between ~640 million and 4.3 billion dollars depending on tech level making it clearly cheaper than microwaves... but it comes with a huge problem. 1/2 of your wire will always be on the hot side of the moon where temperatures reach a boiling 120°C. As a wire heats up, its electrical resistance increases meaning that all of those thousands of kilometers of wire need to be buried pretty deep in order to keep them thermally stable. Here on Earth, it would cost about 3.4 billion dollars in equipment and labor to bury that much wire just 50-70cm under ground. On the moon, you'd have to go much deeper to reach thermal stability... so this method may in fact get to be more expensive than the OP's satellite idea if future tech is good enough at shipping and microwave transmission, but does not make any significant strides in trenching and burial techniques. ### Using "Hydro" Pumped storage A 10MW turbine costs about \$50,000-100,000 and weights in at 35 tons. If you decide to save on weight and spend more on materials, you could probably get a \$1,000,000 turbine down to about 20 tons. Pumped hydro has up to 87% efficiency which should be similar to conveyored sand. Your station needs to store 3600MWH of potential energy which at lunar gravity requires a pair of reservoirs equal to about 8.4 million cubic meters located at different elevations... but due to overlapping craters, such features are naturally common on the moon. This places your total power solution at somewhere between 95 million and 3.3 billion dollars... but like the wire issue, this becomes a gargantuan construction project with a difficult to assess cost to gather all those millions of cubic meters of regolith and terraform the craters into the actual forms you need. It's still probably the best solution that uses science that is well understood today, though. [![enter image description here](https://i.stack.imgur.com/YXszT.png)](https://i.stack.imgur.com/YXszT.png) ## A better near future tech solution: super conductor storage The night time temperature on the moon is about -130°C which is very close to the operating temperature of a few kinds of super-conductors. Super-conductors can hold a massive charge and only suffer about a 5% loss on discharge (the storage itself is lossless). Now how MUCH power a super conductor can store before it hits its critical magnetic field capacity is... complicated to say the least having all sorts of things to do with the size of your wire, temperatures, exact materials, etc. Here it is really difficult to account for future technologies, but using some of the best super conductors currently be experimented with, a bit of refrigeration and daytime sun shielding techniques your results are... still wildly inconclusive. But future tech is your friend here because better super conductors are being invented all the time. If you were to invent a material that is superconductive at room temperature, you could make a passively cooled system that could store 15 days worth of power in ~24 cubic meters. Depending on the density of this super conductor, it could mean a "battery" that only weighs 30-100 tons, and requires practically no additional infrastructure. Depending on how expensive this material is to manufacture, you could be looking at powering each base for under \$100 million... assuming a lot of ideal future tech stuff. [Answer] The Moon is small. With the Apollo missions, the horizon is often only a few hundred yards away. A line of sight energy beam is not going to go far on the Moon before it leaves the surface entirely. The main solution would be to use most of the power close to where it is generated. If you have plants extracting materials from the moon, those would use a lot of power. You can then ship the materials. The Nordic countries use their surplus hydroelectric power to smelt aluminium. [Answer] # Why do you want to make a *grid*? The reason we make a power grid on Earth is because the place where we produce power, and the place we use it, are in separate locations. The factors that affect where we produce power and where we use it are... * Location of natural resources for power generation * Location of natural obstacles for settlement * Location of natural values for settlement * Settlement spread, we want to live in many different places As far as we can tell, there are two ways to create usable energy on Luna: * Solar panels * Nuclear fission / nuclear fusion There is no need to place solar panels far away from a settlement. Why would we want to? There are no special places on Luna that are better than any other to place solar panels. There is no local weather to consider, since lunar weather always comes in "sunny" or "night" everywhere; there are no natural features that make solar panels unsuitable but settlement desirable; there are no natural resources that we risk covering or make less beautiful. And there is no need to place a nuclear reactor far away from a settlement. Because there are no rivers/oceans that we need for cooling. "But what about nuclear accidents?!" you say. This is much less of a problem on Luna because unlike on Earth you do not have *fallout* — i.e. materials *lofting* (no air to be lofted into) and *falling out* of the sky (no rain or wind to make it fall out) — in the same way. Also, as Three Mile Island showed, you can reduce the radionuclide problem of an accident to a minimum with scrubbers. And whatever is left you simply vent in a direction away from the settlement, and let it Newton itself in a nice ballistic trajectory to a designated area. So, to sum things up... * Every place is as good as any other to generate power * Every place is as good as any other to settle * If you can make one settlement self-sufficient, you can make *all* of them self-sufficient. As far as we can tell, *none* of factors first mentioned for separating power production and power consumption by large distances exist on the Moon. So why would you want to build a power *grid* on the Moon? Hence... ## There is no need for a power *grid* on Luna. It makes no sense with centralised power production and subsequent redistribution on the Moon. There is no need to shunt power "thousands of kilometers" on the Moon. So... ## You are trying to solve a problem that does not exist. ]
[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 8 months ago. This post was edited and submitted for review 8 months ago and failed to reopen the post: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/246045/edit) A magic portal between our world and another earthlike one opens near a large city of a first-world country in the present day. Governments on both sides learn about it and take control within days. The aliens on the other planet are at a similar tech level to us (including weaponry!) with relatively similar societies. Their language don't resemble anything close to any human language. The aliens have relatively similar biology (i.e. bipedal, multicellular, DNA based, etc) for reasons that are out of scope of this question. The portal is about 10 metres in diameter, hovering just above ground level, and will not close but cannot be widened or moved. Assuming that both humans and aliens are eager to cooperate, how long would it roughly take, at a minimum, to go from the portal opening, to civilian aliens being able to immigrate and live in the nearby human city? I'm writing a story about one of these immigrating aliens and I want to know roughly how long humans have known about the aliens by the time they're able to move over. [Answer] If both humans and aliens are eager to cooperate and are essentially equals, I would think that emigration would not really be allowed or considered necessary for the common populous until trade relationships had been going on long enough for both sides to get a handle on communication issues, security concerns, and understand how the other society works. Not to mention international agreement with everyone on the same side of the portal. I'm thinking that ten Earth years would be on the fast side of things for all that to happen. If they're both eager to interact and things go well then it's difficult to see it taking longer than 50 years. **EDIT:** Pathogens...let's not forget the pathogens. That could actually put quite a stop to things for decades if not hundreds of years despite the desire to cooperate. It might take decades for the medical researchers to work things out and immigration by the common populous might not even be allowed until natives on both the portal have had sufficient immunological resistance to things on the other side of the portal. That could take...hundreds of years. Immunizing an immigrant against local pathogens is one thing, but it is quite another to protect the all the locals from the immigrants. [Answer] **Until adequate medical trials are complete to prove that we won't kill each other by accident.** I'd guess an absolute minimum of twenty years, allowing for three or four 5-10 year phases of trials, assuming everything goes better than anyone could imagine. The humans will be familiar with the ending of *The War of the Worlds*... and its real life antecedents: the diseases that killed off non-indigenous colonists in sub-Saharan Africa, the diseases brought from Europe and Africa that ravaged the indigenous peoples of the Americas, cross-species plagues affecting livestock, wildlife, and plant life, the threats posed by invasive animal species, and on and on. Presumably the aliens have similar experiences from their own world. If we have similar enough biology to immigrate, so do our microbes and bugs - to each other's planets, bodies, crops, wildlife, etc, with potentially horrific results. Everybody loves making new friends with the nice biologically similar aliens until one of them has a little bit of toenail fungus that turns out to really love eating terrestrial food crops, plunging Earth into a murderous famine that ends with 20% population attrition and the collapse of global civilization. We can walk across the magic portal and start living in harmony with ET thirty seconds after first contact if we want to, but we'd be fatally stupid to try, and they'd be stupid to let us. The sensible thing to do is to treat the portal like the world's most heinous biological weapons facility times a thousand until proven otherwise. Bury it under a mountain of hermetically sealed concrete, quarantine the scientists that work there, and take it slow. Beyond that, I think it's story-based. [Answer] How long does it take from human discovery of a place to settlement? New Zealand was discovered by Europeans in 1642, but it was only in 1840 that enough people were settling that they decided to create the Treaty of Waitangi to (try) settle peacefully with the Maori who were already living there. However, by this time there was already commercial exploitation of the surrounding water by ships hunting whales and seals, and numerous conflicts had already happened. This isn't quite the same as your situation because there was a 6 month sailing voyage to get to New Zealand, but compared to 200 years, 6 months is negligible. So anyway, as a ballpark figure, I'd say 100 years or so from discovery. [Answer] #### Legal Immigration This will take a while, because of concerns about weapons, drugs, disease and many other factors. I don't think it would take 100 years, but before any legal immigration you would have: * Exploratory teams * Political negotiations * Embassies * Trade all of which will take time. If either side tries to move too fast, the other side may assume ill intent, and each side knows that. Plus the language barrier will slow things down initially. Somewhere between 1 and 10 years before you could get to any legal immigration. #### Illegal Immigration One day to one week. Seriously. There will be people on each side who will either see the grass as greener on the other side. Home is: poor, disease-ridden, oppressive, etc. The new place is fantastic by comparison. Or they see opportunities to sell things that are not as profitable in their own world and don't feel like waiting for the politicians and bureaucrats to get everything ready. Some of these people will try to get to the other side as quickly as possible, by sneaking through in the middle of the night, defecting quietly from an official delegation, hitchhiking on a trade caravan, etc. Once they get here, or humans get to the new planet, they will find a way to hide, make friends, change their appearance to more closely match the natives, etc. [Answer] ## One week Lets assume the aliens are on our level of technology and just as xenophobic as humans are. Well, maybe more unified. After initial contact with humans, they send in a single nuke to clear their landing site. Humans, unable to comprehend that the origin is some alien species through a portal and not the US/Russia/China starting a nuclear war, react with nuclear counterstrike on one another. As a result, the Humans eradicate themselves with nuclear fire within a couple of hours to days. Because the humans are mostly gone, the first explorative immigrations start a week later into the wastelands. Some settle in the place closeby, welcomed by the survivors because they bring food. They never learn that the initial nuke of the third world war came from the aliens. ]
[Question] [ I'm writing a story for a character who is a an old monster hunter. In his younger days, he used to make a living by hunting the most dangerous monsters which are basically the story's equivalent of apex predators like tigers or lions. At one time he was tasked to clear a small island of tiger-like monsters, which he did, and he was paid well for that. Later in his life, he returned to that island, only to find that it's been deserted by the people who lived there because of various ecological disasters. With lack of predators, its prey animals bred out of control, which decimated the vegetation to the point where even trees are eaten by the wildlife until there's none left, which ruins the soil and therefore agriculture (not to mention a period where the inhabitants on the island spend more time fighting off herbivores eating their crops than actually farming). This caused him to realize the error of his ways and he decided to be more conservative in his work, only hunting when it's absolutely necessary and even protecting monsters that are important to the ecosystem. My question is, is this sort of ecological disaster even possible in a person's lifetime (ideally maybe 20-30 years)? The world of the story is inspired by Monster Hunter where fire or thunder breathing dinosaurs are quite normal and part of the ecosystem, so the science may be able to stretch a little bit. [Answer] Yes, it can. A very similar thing has in fact happened on St Matthew Island, a smallish island in the Bering Sea off the coast of Alaska, where the US Coast Guard brought 29 reindeer in 1944 to serve as an emergency food supply for a local outpost. The outpost closed a few years later, leaving the reindeer behind. With no predators, they shot up in number, reaching some 6,000 by 1963, by which time they have eaten up most of the island's lichen, a crucial winter fodder. At this point a particularly severe winter caused the reindeer population to crash, and they were completely gone by the 1980s. But in your setting, humans (farmers) remain after the tiger-equivalents are gone, and would be capable of replacing them as an apex predator... unless their society has a mechanism which prevents this? [Answer] Yes, the reduction of an ecosystem's health can be seen within the lifetime of one person. On the bright side, the reverse can also be true. One real world instance of the crash and recovery of an ecosystem within a person's lifetime was the extermination of wolves within Yellowstone in the US. The wolves were killed off in the 1930's. While the local elk were still preyed on by bears and cougars (and maybe coyotes), the lack of wolves removed a huge amount of predatory pressure. This allowed the elk population to grow enough to push the limits on the carrying capacity of Yellowstone. With the lessened predation pressure, the elk would leisurely browse on the young willow, aspen, and cottonwood, which was quite hard on the beaver population, who needed willows to survive the winter. Without the beavers and their dams, the streams became clouded with silt and their shorelines had little vegetation, as what little there was was cropped or trampled by grazers. When the wolves were reintroduced to Yellowstone, the area was fairly ecologically pour, with low populations of fish, small mammals, and birds, and the landscape around streams were mostly cleared by the elk and deer, which resulted in quite a lot of soil being washed into the streams. Soon after the reintroduction, even with a low starting population of wolves, the elk and deer no longer felt safe loitering near the streams, and so the bushes and trees near the streams were able to grow and thrive. The beavers were able to thrive with the availability of the young willows, and with the increase in beaver population, new dams and ponds were created. The beaver dams evened out the seasonal pulses of runoff, slowed the water which allowed the water table to be recharged, and the beaver ponds provided cold, shaded water for fish. The newly robust willow stands also provided good habitat for songbirds. The streamside vegetation was also a boon for small mammals, giving them food and shelter. Even with this shelter, the large increase in their population meant that the coyote population also had a large increase in available food. The scavenger populations also benefited, as instead of elk carrion being primarily available as winter-killed, it was now available year round as wolf-killed. The elk populations themselves also benefited. Currently elk populations are about 3 times what they were, as the ecological health of the area has increased so much that there is plenty of forage for the elk, though they do have to migrate around to find it. Their forced migration to avoid wolves gives them access to additional food sources, while preventing them from overgrazing areas, which allows previously grazed areas to recover much more quickly. [Wolf Reintroduction Changes Ecosystem in Yellowstone](https://www.yellowstonepark.com/things-to-do/wildlife/wolf-reintroduction-changes-ecosystem/) [Answer] Forget "lifetime". You can see it in a single year. The Grand Canyon Game Preserve (a predecessor to the modern [Kaibab National Forest](https://en.wikipedia.org/wiki/Kaibab_National_Forest)) was originally managed to maximize deer and elk populations for hunting, primarily by killing off predators (cougars and coyotes). Initially, it was wildly successful: hunters reported finding game animals in unheard-of numbers. A few years after management started, though, a winter was slightly harsher than average. The deer and elk stripped the forest of edible vegetation, then starved to death. It took half a century for animal populations to return to pre-management levels, and the trees are still recovering. ]
[Question] [ I have a hypothetical scenario in which Mars flies over Jupiter at close range. I want to make Mars disintegrate entirely in this scenario while keeping the scenario scientifically accurate (please ignore the part about why Mars leaves its orbit). The outline of my scenario is as follows: * Mars goes deep into Jupiter's Roche limit. At the closest point, the surface of Mars can be as close as 1000 km from Jupiter's tropopause if necessary. * Before the fly-over, Mars's rotation can be accelerated to up to 1 Martian day per hour if that helps Mars to disintegrate. * Mars can fly over Jupiter with any relative orientation, i.e. it can have its pole or equator or anything in between facing Jupiter, whichever helps it to disintegrate. * Mars has only one chance to fly over Jupiter. (It's okay if Jupiter captures Mars or all the remains of it in orbit. But if Mars survives this fly-over and escapes Jupiter, and encounters Jupiter again in the future, the outcomes of those encounters do not matter for this question.) * You can use the gravitational slingshot effect of Jupiter if that helps Mars to disintegrate. * You can use millions of super-deep drillings and nuclear bombs to introduce fractures in the Martian crust if that helps. And my question is: **Can Mars disintegrate entirely in this scenario, given the conditions above?** Here, "disintegrate entirely" means that no fragments of Mars should have a mass greater than 1% Martian mass. Also, most of Mars' mass should not fall into (the atmosphere of) Jupiter. [Answer] **Yes, and no need to introduce fast rotation, or nukes or anything similar.** The Roche limit for liquid bodies is $d=2.544R \sqrt[3]{\frac{\rho\_M}{\rho\_m}}$, where $R$ is the radius of the more massive body, and $\rho\_M$ and $\rho\_m$ are the densities of the more and less massive bodies, respectfully. Using $R \approx 71,492 \text{ km}$, $\rho\_M \approx 1326 \frac{\text{kg}}{\text{m}^3}$, and $\rho\_m \approx 3930 \frac{\text{kg}}{\text{m}^3}$, I get $d \approx 122,187 \text{ km}$. Shoemaker Levy-9 was shredded when it passed at about $96,000 \text{ km}$ and it was estimated at a tiny 1.2-1.7 km diameter sphere. If Mars passed through an orbit at this distance, as it approached perijove the initial tidal forces would crack its crust like a pool ball in a vise. Those fragments would continue to break apart and separate until small enough that their cohesive forces outweighed the tidal forces. Mars' liquid core would separate into small droplets. It is doubtful that solid crust fragments much larger than Shoemaker Levy-9 would remain intact, which would be much, much smaller than 1% of Mars. Note that Mars's paltry radius of less than $3400 \text{ km}$ would mean the entirety of Mars would be within the Roche boundary, while not reaching the cloud tops of Jupiter at about $71,492 \text{ km}$. Similar to the fragments of Shoemaker Levy-9, most of the Martian fragments would not re-coalesce as their minor mutual gravitation would have negligible effects on their orbit compared to the close by and massive Jupiter. By the time they were out of Jupiter's Hill Sphere (assuming a sufficiently high velocity pass), the fragments' differential velocity would exceed mutual escape velocity and the Sun would dominate their resulting orbits. The closer Mars passes to Jupiter, the smaller the resulting fragments! [Answer] One part of the question says: > > Before the fly-over, Mars's rotation can be accelerated to up to 1 Martian day per hour if that helps Mars to disintegrate. > > > Would that help Mars break up into pieces? It might. *Habitable Planets for Man*, Stephen Ho. Dole, 1964, pp. 58-60, says that the lower limit for the length of day of a habitable planet would be when the planet rotates so fast that material on the equator reached orbital velocity. <https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf> Dole also discusses how rotation rates can affect the shapes of planets on pages 41-48. Mars has a mean radius of 3,389.5 kilometers and an equatorial radius of about 3,396.2 plus or minus 0.1 kilometers. Thus it has an equatorial circumference of about 21,338.935 kilometers. If Mars rotated once in one Earth hour of 3,600 seconds it would rotate at about 21,338.935 kilometers per hour or about 5.9274819 kilometers per second. That is larger than the orbital velocity at the Martian surface. In fact it is also larger than the Martian escape velocity (at the surface) of 5.027 kilometers per second. So if Mars stars rotating that fast a lot of Martian material will fly away at more than escape velocity, and a lot of other material will start to orbit the planet. But that would not be enough to make Mars entirely disintegrate. You want no chunks of Mars larger than 1 percent of the Martian mass to remain. If all of Mars had the same density as its overall density a body with 0.01 the volume of Mars would have 0.01 the mass of Mars. According to my rough calculations the cube root of 0.01 is approximately 0.2154444. So a spherical object with the overall density of Mars and 0.01 Mars' mass would have 0.01 of Mar's volume and thus a radius of 0.2154444 of Mars' radius and thus a radius of 730.24843 kilometers. Such an object would probably be pulled into a spheroidal shape by its gravity, though it might take a long time for a jagged Martian fragment to do so. Since the Martian crust, mantle, and core have different average densities, crust and mantle fragments with 1 percent of the mass of Mars would be larger, and core g fragments with 0.01 percent the mass of Mass would be smaller, than calculated above. The Martian iron nickel sulfur core is quite large, believed to have a radius of 1,794 kilometers (1,115 miles) plus or minus 65 kilometers. The Martian core is partially fluid. <https://planetary-science.org/mars-research/internal-structure-of-mars/> > > The Martian core radius is more than half the radius of Mars and about half the size of the Earth's core. This is somewhat larger than models predicted, suggesting that the core contains some amount of lighter elements like oxygen and hydrogen in addition to the iron–nickel alloy and about 15% of sulfur.[36][37] > > > <https://en.wikipedia.org/wiki/Mars#Internal_structure> Guessing that a chunk of Martian core that had 0.01 of the total mass of Mars might have a radius of only maybe 500 kilometers, twenty or thirty of them might fit within the core of Mars. Thus the Martian core might have to broken up into many smaller pieces so that none of the pieces had more than 0.01 of Mars's total mass. There isn't much problem with breaking up the parts of the Martian core which are still fluid. If Mars spins rapidly enough, or passes close enough to jupiter, the fluid parts of the Martian core will find themselves in orbit around the remnant of Mars or even escaping from Mars. But the solid inner core of Mars would be a problem. It would have originally been molten and gradually cooled to solid state over billions of years. So it would be essentially a single giant piece of solid metal and other materials. It would not be held together merely by its gravity but also by electrochemical attraction between its atoms and molecules. And those bounds might be harder to break than those of gravity and require greater stress. If Mars does break up and the pieces go into orbit around Jupiter, it would become like a super asteroid belt for space mining. [Answer] Keeping in mind many of the theories of the [Formation and evolution of main rings](https://en.wikipedia.org/wiki/Rings_of_Saturn). And as you mentioned Mars could travels within the Roche limit, Édouard Roche himself proposed that the rings are part of a large moon or captured planet that simply got too close. The only question I would have would be the time frame of such an interaction would take place across and if it is within your criteria of the mass being disrupted down to %1 of Mars original mass. [Answer] Given > > " ... You can use millions of super-deep drillings and nuclear bombs to introduce fractures in the Martian crust if that helps.." > > > then Ender Wiggins and [Dr Device](https://everything2.com/title/Dr.+Device) can make it a certainty, with or without Jupiter. ]
[Question] [ In stereotypical fantasy, there is normally some sort of revolution in a uni-polar world where the rebels have to fight the evil empire. (This is not always true but its basically what happens) The "empire" either is the only country that exists or sits alone on a continent etc... These are semi-plausible excuses since (I would imagine) in the old times, when the Roman/ Chinese empires had a civil war/ revolutions, they were mostly self contained w/ Romans fighting each other or Chinese fighting each other. While there were foreign/ barbarian mercenaries and such, its not like the leader of the Germans sent in an expeditionary force to provide humanitarian aid or something. Again the no outsiders/ foreigners rule does not always hold true as after the fall of the Ming, the Manchu (who were still apart of the Ming Dynasty but were considered "outsiders") took advantage of the situation to take power. In our modern world, whenever there is conflict, its used as a proxy war by other powers to push some sort of goal. The powers funnel arms, money and even sometimes troops to accomplish their goal. The war in Yemen has KSA + USA vs Iran. The war in the Ukrainian has western countries pumping in weapons and money and even before that the war in the Donbas region had Ukraine and the West vs the rebel with support of Russia. Syria had Russian + Iran vs the US and some others. Even in tiny countries this happens see <https://en.wikipedia.org/wiki/2021_Solomon_Islands_unrest> where China + Australia intervened. Would it even be possible in our modern interconnected world for there to be just a civil war in a populated country (think US, China, India, Brazil etc...) without its rivals swooping in to aid a favored side? Would it be possible in the future via some invented technologies? thanks [Answer] **Yes, but not often** The issue is globalisation. There is no single advanced country on Earth today that produces everything it consumes / uses. Every country specialises in certain products for export and imports everything else. Which means that any time a country becomes embroiled in a war then it means that sellers in other countries are losing a market, which may be economically inconvenient or disastrous depending on the market. Even worse is where a war-affected country is no longer able to export at least one essential commodity. To look at a current example, Ukraine's wheat production is a key part of the global food economy, the cost of food worldwide is going to increase as a result of the current invasion. Even if a country does not produce critical exports, conflict with or within that nation can threaten to spill over into neighbouring countries and/or endanger trade routes. Furthermore, wars will almost always result in people fleeing the conflict, meaning that nearby countries will need to deal with refugees that are likely to require some initial economic support at least and may represent a security risk. So countries that are nearby or otherwise going to be affected have an interest in trying to shut down a war or try to influence its course so that the final outcome is less bad for themselves. (It's never good.) Finally, increased global mobility means that there are pockets of people all over the world who are likely to get upset about what is happening in "their" old homeland. Even if governments of other countries do not get involved, individuals in those countries may start organising financial or logistics backing for one side or another and in extreme cases start recruiting combatants. Having to explain the actions of its citizens gives another incentive for otherwise uninvolved governments to try to settle conflicts elsewhere. However, there are some wars where the rest of the world tends to stand back and do very little other than make some noises in the UN and, in recent times, impose individual sanctions only. The [2021 coup in Myanmar](https://en.wikipedia.org/wiki/2021_Myanmar_coup_d%27%C3%A9tat) is an example of this - given the ongoing internal hostilities and death toll this may be considered a civil war. Some countries appear to be attempting to gain favour with the military junta through sales of arms and other economic activities, but I suggest that this alone does not make the conflict a proxy war. (I am not attempting to condone or excuse any of the violence in Myanmar or those supporting it, merely define what it is and what it is not.) The [Rwandan genocide](https://en.wikipedia.org/wiki/Rwandan_genocide) in the 1990s is another example of a conflict which does not constitute a proxy war. While there was a United Nations contingent present, political considerations reduced them to a bystander role. The incomprehensible violence that occurred was not promoted by any major foreign power. (Whether the western powers could have reduced the bloodshed if there had been more political will to intervene and/or the UN Department of Peacekeeping Operations had not prevented the seizure of weapons before the genocide commenced is a separate issue.) TLDR - There are wars where major powers try not to get involved, they are the ones that you don't hear much about. However, given the interconnected nature of the modern world economy, many conflicts will have sufficient economic impact that the major nations have an interest in the outcome and will attempt to exert influence. [Answer] **Large Country** If a small country has a civil war, larger countries get involved to push their own agenda. Often this agenda is to oppose their rival countries who support the other faction of the civil war. For example USA and Russian in Yemen. It does not really matter to either USA or Russia what happens in Yemen. Yemen is a small far-away country and even if the Russia-supported faction gets into power, Yemen is a small far-away country and has no influence on the USA. The main concern of the USA is (a) to intimidate the Russians and (b) keep happy their allies who are physically closer to Yemen. However if the USA has a civil war inside itself, and the war looks undecided -- for example one side has the Land Army and the other has the Water Army and Flying Army -- then the other countries back off. Former enemies of America are happy for the country to destroy itself. Former allies want to ally with the new America after the war -- whoever wins. The worst thing to happen is to choose sides, then have your side lose, and start as enemies of the new superpower. Better to keep the head down and try to ally with whoever wins. [Answer] For a foreign country to chip in a civil war, there must be some of their interests touched by the war that they want to protect. For example resources like water, oil, minerals, transit rights, are good reason to take a side in a civil war. Even for banana plantations governments have been thrown away... If none of them are present, the only interest a foreign country might have is to sell weapons to both parties, possibly in a way that keeps the balance and ensure future weapons sales. [Answer] > > Would it even be possible in our modern interconnected world for there > to be just a civil war in a populated country (think US, China, India, > Brazil etc...) without its rivals swooping in to aid a favored side? > > > **Gang wars.** <https://en.wikipedia.org/wiki/Saint_Valentine%27s_Day_Massacre> > > The Saint Valentine's Day Massacre was the murder of seven members and > associates of Chicago's North Side Gang that occurred on Saint > Valentine's Day 1929. The men were gathered at a Lincoln Park, Chicago > garage on the morning of February 14, 1929. They were lined up against > a wall and shot by four unknown assailants, two dressed as police > officers. The incident resulted from the struggle to control organized > crime in the city during Prohibition between the Irish North Siders, > headed by George "Bugs" Moran, and their Italian Chicago Outfit rivals > led by Al Capone.[1] > > > Organized criminal groups have jurisdictions over which they exert control, just as sanctioned political groups do. Sometimes the one merges into the other, as when groups that seem to be terrorist groups (or perhaps originated as such) fill a void and provide governmental services for the people in their territory. Sometimes the groups are not gangs operating illegally in the context of a standard government, like the gangs of old Chicago or modern Los Angeles. Warlords might be all there are, like in the Somalia of Black Hawk Down or fallen Libya. There can definitely be violent conflicts in such scenarios: a splinter group or rival group wants to take control and the two groups clash. This could be called a gang war. Outside groups are unlikely to get involved with internecine warfare confined to a city or territory - especially if all parties are considered criminal groups. [Answer] Tributary state wars If the world has one dominant state, but not just one state. There are still numerous other independent states. The dominant state may behave like China did in the past (<https://en.wikipedia.org/wiki/Tributary_system_of_China>) --as long as the other states pay tribute, conflicts between these states may be ignored by the dominant state. The dominant state could also prevent other states from intervening and have a policy of allowing internal conflicts to progress unimpeded. [Answer] Nuclear deterrence? If India and Pakistan had a nuclear war, subject to diplomacy having made both of them somewhat isolated if it wasn't spilling over, I doubt anyone else would want to get involved. Quite the opposite, other nations would probably broadcast how NOT involved they were. Ditto a (say) UK civil war. ]
[Question] [ So here is the basic setup. The parasite lives in the cells of it hosts and can only spread via reproduction, and will spread 100% of the time to a child regardless if the infected was the mother or the father. The infected are strongly encouraged to raise families with the uninfected. For the sake of simplicity, we shall assume all marriages are infected / uninfected matches. The parasite lowers human fertility by about 50%, and culturally the infected are encouraged to keep family size small as well. The parasite causes mutations that are highly advantageous at keeping the host alive, especially in regards to disease. To keep the maths simple, we should just assume death by disease before having children is 75% lower and death by violence and accidents is 50% lower. A newly infected child is added to the general population pool about every 75 years or so. Sometimes two are added, but for the sake of number crunching we shall call it 1.25 children. Now let’s assume we start with one infected person in a postion of high nobility in a setting similar to Norman England in 1066 and the setting follows the same broad trends as England in regards to population growth and mortality rates, how long is it going to take to spread? [Answer] **The English will all be infected by the mid 1600s.** [![english population](https://i.stack.imgur.com/Th4vh.png)](https://i.stack.imgur.com/Th4vh.png) <https://ourworldindata.org/grapher/population-of-england-millennium> Let us simplify assumptions. We will have 2 infected progeny replace their own 2 parents every 25 years. Assume each pair of parents is 1 infected 1 noninfected. The next generation their children are 2 infected. 2 infected the next generation become 4 infected etc. This takes into account lower reproductive rate and also better survival. Thus the number of infected is 2^(# generations since 1066). I did it in excel to see when it would catch up with the English population. [![excel](https://i.stack.imgur.com/MNG6m.png)](https://i.stack.imgur.com/MNG6m.png) The infected will be the entire population of England between 1616 (4194304 infected) and 1641 (8588608 infected). This sidesteps emigration, the difficulty of finding noninfected mates in the 1600s, etc. [Answer] Assume the following: a generation is roughly 25 years (analysis shows it can vary, but this is a reasonable number). The number of ancestors one theoretically has at generation $n$ is $2^n$. Thus, at 100 years (4 generations previously) there's 16 ancestors, at 200 years 256, at 300 years 4,096, and so on. Looking at it another way, for a given population of $P$ people, the number of generations you have to go back for the Most Recent Common Ancestor (MRCA) is $\log\_2 P$. However, that has an issue in this scenario because it only says when the MRCA lived: there's no guarantee that the MRCA is the one who carried the parasite. What you also want to look at is the [Identical Ancestors Point](https://en.wikipedia.org/wiki/Identical_ancestors_point) (IAP): that's the generation where everyone either has *no* descendants alive now, or is an ancestor of *everyone* alive now. That sets the outer margin for how long ago the initial parasitized individual *must* have lived. So patient 0 had to be between the IAP and the generation which had the MRCA (which is the latest he could have lived to have everyone later be a carrier). Chang (cited in the link above) calculated that in a population of size $P$, the IAP was $1.77\log\_2 P$ generations ago. So, a spreadsheet easily works this out: we take the population of Great Britain at given points in history, and calculate, at that point, how long ago before that date the MRCA and IAP were. If 25 \* the number of generations falls around 1066, then we know for each. In 1600, the population of the island of Great Britain was about [5.2 million people](https://en.wikipedia.org/wiki/List_of_countries_by_population_in_1600). Calculating the MRCA ancestor puts that person being alive around 1042. That's actually pretty close to our 1066 date, and given the margins of error inherent in things like generation length and such, we can probably safely use that as an estimate. So the *earliest* everyone in Great Britain would carry the parasite is around 1600. Now we're looking at the IAP. And here we run into an interesting issue: in 2000 the population of Great Britain was 59 million, but that only puts the IAP in 858. So, theoretically speaking, its possible that not everyone in Great Britain (not counting recent immigrants) would be infected yet. It would be highly unlikely, but possible. However, given the point that infected will preferentially mate with uninfected, it's much more likely the point of 100% infection would fall a lot closer to the MRCA than it would the IAP. All in all, you're safe saying that it would happen sometime in the 17th century. Now, this raises an interesting point because this is exactly around the time the British started going big into the colonization game around the world. The parasite will have certainly spread across most of Europe by this point, but it's going to explode across the entire planet in very short order after that. ]
[Question] [ In the world I am making their is a species of wyvern like monsters that hunt in groups of 10 to 20 in the aftermath of the storms they make and have wingspans that range from 20 ft to 36 ft. Other relevant information * A wyvern's average body temperature when hunting exceeds that of 110 degrees Fahrenheit. * The average wyvern has a large amount of heat shed during hunting. ## The Question Could a flock of these creatures realistically cause a the forming of a EF0 tornado or greater just from them flying in a formation and the body heat they are giving off? [Answer] ## A small group of large flying creatures, no. ## ...but a large group of small flying creatures, yes. The photo below is not a tornado, but a "bugnato" caused by a massive swarm of mosquitoes. As animals flap their wings, they make the air around them move faster which slightly reduces the ambient air pressure. Amongst a small group of flying animals like your typical flock of birds, this effect is not a super big deal because each member of the flock is much stronger than the over all pressure gradient caused by their flapping, but when you get millions or billions of insects flying in close formation the ambient pressure difference can become stronger than any individual member's flying power. When this happens, the insects get sucked into flying in a circle instead of straight. As they get sucked in they are forced to fly closer together which makes the vortex even stronger; so, only once your flock/swarm size gets big enough that no individual member is strong enough to resist the overall vortex does a tornado like phenomenon happen. The biggest problem with your wyvrens is that it does not matter how strong any one of their wing flaps are, without enough of them they can not create a tornado. Their wing flaps could make a lot of turbulence, but not give that turbulence enough structure to turn into a vortex. In some settings, Wyvrens are basically treated as plague dragons breathing some sort of toxic or disease carrying breath weapon instead of fire; so, if you were to take this general concept but make them breath swarms insects as their breath weapon, then perhaps enough wyvrens working together could breath a bugnato into existence. [![## Your vectors are all wrong](https://i.stack.imgur.com/6bjDi.png)](https://i.stack.imgur.com/6bjDi.png) *FYI: Windspeeds in a bugnato are much lower than a tornado so while they look a lot like a tornado, they do not move nearly fast enough to cause structural damage.* ### ... but if they breath fire, they could make a fire tornado When you create a circle of fire, it consumes the oxygen in the middle of the circle much faster than around the outside of the circle. This creates a vacuum that pulls the surrounding flames inward forming a fire vortex. So if your Wyverns were to breath fire in a circle around a target, their flames would come together and consume whatever is in the middle in a tornado made out fire. [![enter image description here](https://i.stack.imgur.com/TUPle.png)](https://i.stack.imgur.com/TUPle.png) [Answer] No, they don't use enough energy. A bald eagle [has around 650 joules of kinetic energy](https://chem.libretexts.org/Ancillary_Materials/Exemplars_and_Case_Studies/Exemplars/Biology/The_Energy_of_Bird_Flight) to fly at full speed. [A tornado contains around 10,000 kilowatt hours](https://www.physicsforums.com/threads/energy-and-power-of-tornados.501504/) or around 36 billion joules. Lets assume ten birds fly for an hour, and constantly use the amount of energy a bald eagle uses to stop from full speed in a second every second. 650 \* 3600 \* 10= 20 million joules. That's nowhere close to the amount of energy. You're a thousand times off. Even if the animals got larger, or they got more numerous you'd be nowhere close. [Answer] **Maybe a smaller vortex than a tornado?** [![enter image description here](https://i.stack.imgur.com/NwUTi.png)](https://i.stack.imgur.com/NwUTi.png) <https://www.livescience.com/bubble-net-whales-video.html> Tornados are freaking powerful. They would be tough on fliers of the size you describe. But maybe they could make smaller vortices? These whales make nets of bubbles and so not actual swirling vortices. But I could imagine your creatures making smaller vortices. [![wingtip vortex](https://i.stack.imgur.com/Wx90X.jpg)](https://i.stack.imgur.com/Wx90X.jpg) <https://www.boldmethod.com/blog/lists/2017/02/5-factors-that-affect-vortex-strength/> Your fliers cruise through a flock of their prey. The trailing vortex concentrates the prey animals and knockes them off balance. Following wyverns go through the center of the vortex and scoop up a number of animals. [Answer] [![enter image description here](https://i.stack.imgur.com/BmGmR.png)](https://i.stack.imgur.com/BmGmR.png) Here is an picture of a F5 tornado that struck Moore in 1997. And here's daddy [![enter image description here](https://i.stack.imgur.com/kM9SD.png)](https://i.stack.imgur.com/kM9SD.png) That's right, you are looking at a supercell, gigantic behemoths of thunderstorms that extend as high as 70,000 ft, and the father of hail, torrential rain and (of course) tornadoes. Although you requested for an "EF0" tornado, I still described the F5 tornado. Because, tornadoes are notoriously difficult to produce. Let's see how tornadoes are formed- -**Hot, humid air**- In order to have even a decent garden-variety thunderstorm (forget supercells) you need massive amounts of hot, humid air. Sure, 43°C sounds pretty balmy, but there is a reason why you can't make tornadoes with a few flying creatures shedding off body heat. Try out this activity at home. Take some boiling water, and pour it into a bucket of water at ,let's say, 40°C). The bucket gets just lukewarm, or maybe not even warm up at all. Heat does not just depend on energy, it also depends on the mass of the object. A bucket of water at 40°C contains more overall heat than a cup containing water at 100°. This also applies to gases (including air) as well. When you get warm air, it creates updrafts, often containing moisture. This moisture, when it contacts the cooler, upper atmosphere, it condenses to form clouds. Just normal fluffy or wispy clouds. End of story. But, if you have a lot, on the order of thousands or even millions of tons (yes, tons) of warm air, then as it cools down, it rapidly transfers its latent heat to the surrounding air, causing it to suck up even more air, and this air also releases its latent heat. This chain reaction goes till you end up with a rather tall and hefty anvil cloud. The latent heat released is immense, on the order of millions or even billions of joules. [![enter image description here](https://i.stack.imgur.com/yWILn.png)](https://i.stack.imgur.com/yWILn.png) -**Wind shear**- Wind speeds and directions can vary with altitude. I doubt whether your 40ft wyverns can change wind direction just by flying. Have you ever noticed (in an apartment) how the terrace is windy, whereas the air is still at ground level? When you get two horizontal air currents that have different directions and speeds, they form a horizontal air vortex, which is basically the parent vortex of the tornado, or the mesocyclone.[![enter image description here](https://i.stack.imgur.com/QCJwF.png)](https://i.stack.imgur.com/QCJwF.png) Image of an mesocyclone:[![enter image description here](https://i.stack.imgur.com/QzFtw.png)](https://i.stack.imgur.com/QzFtw.png) -**What goes up, must come down**-Updrafts do not last forever. Especially if you lift air to freezing altitudes, then it will rapidly cool and sink back to the surface. These are what meteorologists call **downdrafts**, and these are the key features that drive microbursts and heat bursts (caused due to adiabatic heating of rapidly sinking air parcels) Updrafts and downdrafts, when combined, have a notorious knack for rubbing hail against smaller ice pellets, this friction is basically what causes lightning in thunderstorms. (Of course, don't go to your refridgerator and rub ice cubes against frost to create electricity, you need a tad lot more to generate lightning) So, your downdrafts are gonna tilt your horizontal air vortex downwards, and well, there you have it, a tornado is born. So, coming back to the question: -You need a lot more wyverns in your flock, think on the order of millions of wyverns. The best that a flock of 20 flying creatures can do it to stir up a dust devil (albeit very weak and short lived). -If you want your wyverns to create a massive warm-air parcel, for a flock of 20 creatures, you would need to have body temperatures on the order of hundreds or even thousands of degrees (Rip wyvern). The best case scenario I can think for your novel is that an entire kingdom of wyverns have gone fishing for a festival (use story license), and while hunting, they create a lot of hot air over the lake where they are fishing, and accidentally trigger a supercell. And maybe trigger wind shear from the sheer amount of wyverns that are fleeing in different directions and trigger a small tornado. You just need a lot of wyverns to do the job. ]
[Question] [ Individual tidally locked planets or moons are a relatively common topic, but I was wondering if it would at all be possible for an entire solar system's celestial bodies to orbit and rotate at just the right speeds to make it seem like none of the bodies are moving at all and that, to an observer standing on one of the planets, only the stars themselves seem to be moving along the night sky. Basically everything would be so tidally locked to everything else that if you used a telescope on one of the planets you'd always see the same sides to everything at all times and they'd never move from their position in the night sky, except for the stars of other solar systems. **Can an entire solar system's celestial bodies have just the right orbital and rotational speeds be locked in this way?** [Answer] For a naturally evolving planetary system, it is very unlikely. But if you hire even a novice planetary system engineer, s/he will arrange for you a system with as many planets as you want (more than two, though) so "that, to an observer standing on one of the planets, only the stars themselves seem to be moving along the night sky." The trick is to make all the planets of equal mass and distribute them equally spaced on a circular orbit around the central star. Tidal locking them to the central star is a given, yes A slightly more professional planetary system engineer may throw in some minor celestial bodies, also equally spaces in the generalized Lagrange points of such a system. --- A mind-blowing "practical" extension on the idea in the answer - highly grateful to @ARogueAnt. for posting it in the comments [The Ultimate Engineered Solar System](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/). Let the numbers speak for themselves: > > The Sun’s habitable zone can fit 57 mega-Earths (10 Earth-mass planets), 252 Earths, or a whopping 1157 Marses! Holy banana pancakes Batman! > > > [Answer] You couldn't have more than one planet, but if you had only one planet it could happen. The planet would have to have the same orbital period around the star as the rotation period of the star, and it would have to be tidally locked. It could also not have a moon as then that moon would be seen revolving around the planet. I'm sure it's possible that such a system could evolve naturally, but it's going to be a very low chance probably of such a thing happening given how precise all things would have to fall in place. For that planet to then have a zone where life can evolve, and for it to actually do so, makes it even more unlikely. For that life than to develop intelligence to the point it can make for an interesting race to base your story around, even more unlikely. [Answer] # Try a hierarchy of similar orbital periods The orbital period is 2 pi sqrt(r^3/m), where r is the radius of the orbit (has to be circular here!) and m is the reduced mass of the system (approximately, mass of the larger object). Start with a binary star system and put your planet at, oh, the L4 point of the smaller star. If you tidally lock it, the stars are always at the same position in the sky. Now, make the planet, say, 1/2000 the mass of one of the stars. (1/1000 of their reduced mass). Then a moon should revolve around it with the same period, if it is at 1/10 the distance between the stars. Now, make a submoon, say, 1/125 the mass of the planet, revolving at 1/5 the distance of the moon from the planet... and perhaps others at the Trojan points of the *planet* relative to the stars. I will admit, this is a many-body problem and I am handwaving at things like Hill spheres ... you're going to need a proper simulation to know. But it ought to be possible to come up with *something*... [Answer] Tidal locking work from one body to only another one. E.g. our Moon is tidally locked to us, and we always see the same side, but to an observer on another planet it appears to be rotating and its whole surface will (in principle) be visible. Take Pluto: it's tidally locked to its satellite Charon, but we have been able to see it rotating and determine the duration of its day. If you wait long enough (probably longer than the star life) an entire solar system can develop tidal locking to either the central star or the most attractive body around (with attractive I mean exercising the greatest tidal influence), but you would still be seeing those bodies revolving. ]
[Question] [ So, suppose there exists an island (roughly the same size as Hawaii's big island) which is located well in the Arctic (or Antarctic) Circle, but magically has a tropical rainforest climate (warm temperatures, lots of rain, and bright sunlight even when the rest of the hemisphere is experiencing polar night.) The climate is maintained by magical means, and has existed this way since before the evolution of modern humans, at the very least. It may have existed this way for much longer. At least part of the magic works by maintaining an artificial sun over the island (much smaller than the real one, located within the upper atmosphere. The artificial sun does not provide significant light or heat outside of the island's immediate vicinity.) This artificial sun shines only on the island and the water within an arbitrary distance. Let's say that this distance is five miles, just for the sake of argument. What climatic effects would this have on the island (outside of the artificial tropical climate), the local region, and the world as a whole? I am looking for weather, climate, and biological effects particularly, but any other notable effects I would like to hear. [Answer] ### Result *Permanent* hurricane, one order of magnitude more powerful than your run of the mill ones. And you can forget "the eye of the hurricane" - that happens when the hurricane gathers energy over large expanses of warm ocean water. For this one, it is the center of the thing where the energy is pumped into the air column - you will get a permanent warm (say at 293K) whirlwind, ascending in the center, fed at the base by a cold air (at 253K) rushing in from all sides and subject to Coriolis "force" (if you remember, the strength of the Coriolis effect is the strongest at the poles, it goes with the $sin(latitude)$). [A fire-tornado of sorts](https://www.youtube.com/watch?v=1BxQd6AGYiI), not that hot as one over a forest fire, but quite strong with the amount of incoming power (over a small surface) it has to dissipate. ### Production Hawaii has a surface area of 28,311 km² = 28.311e9m². Is situated on 19.8968° N latitude - in average per year it receives ([Lambert's cosine law](https://en.wikipedia.org/wiki/Lambert%27s_cosine_law)) 94% of the total energy flux of a surface with the solar radiation at normal incidence. The solar constant at Earth surface after passing through atmosphere on a sunny day is [1025W/m²](https://en.wikipedia.org/wiki/Solar_constant#Variations_due_to_atmospheric_conditions). The total power your island receives is $28.311e9 m^2 \cdot 1025W/m^2 \cdot 0.94 = 2.73e13W = 27.2TW$ First perspective point - the total power the island receives is: * about a Hiroshima bomb exploring every 2.4 seconds (and having the energy dissipated over the entire area of the island) * about 12 times the average electric power generated on Earth in 2008 (which is [2311.4GW = 2.3114TW](https://en.wikipedia.org/wiki/Electricity_generation#Production)) ### Consumption Let's say that the island is all green and lush at a moment (won't be for long, I promise). Some energy will go into photosynthesis - say about 5% of it (yes, plants have [terrible efficiencies in using the energy](https://en.wikipedia.org/wiki/Photosynthetic_efficiency#Plants) - lucky us, we can keep warmer) Part of the energy will go in making the rain. Oh, hang on, the same energy that goes into evaporating water is released when the water condenses and falls as rain. So no, while there may be some fluctuations, on average there's no actual consumption, just forget I considered it. Part of the energy will escape to the vacuum of space as radiation. That's again a bit [6/117 = 5.1%](http://www.ces.fau.edu/nasa/module-2/energy-budget.php) (look at "The Radiation Balance at Earth’s Surface" and note the "Only 6 of these 117 units are emitted into space beyond Earth’s atmosphere"). actually, that's a nice diagram Let's say part of it is used by the inhabitants - hang on, unless they use the energy to create fuel (eerrr.... energy rich substances, that they'll export as such, as an energy sink), that part of the energy they are "using" is actually transformed back into heat. No dice. So, bottom line. 10% of the energy lost on any other ways except heating the air. Which means the 90% (= 24.48TW) rest of the 27.7TW is going to heat the air above the island. That's gonna be quite an impressive [thermal](https://en.wikipedia.org/wiki/Thermal), the paragliders there should be delighted, isn't it? Well, isn't it? Except... *that* the temperature differential between the island and the rest of the frozen sea around and that lotsa cold air that will want to get warm itself above your beautiful island! **And that spells a huge trouble** **Second perspective point** **The power developed by a hurricane winds [is a puny 1.5 terrawatts](https://www.smithsonianmag.com/innovation/can-we-capture-energy-hurricane-180960750/). And you have 16 times more to dissipate in an area thousands time smaller than the one a hurricane spans!** > > So while wind is only a small part of the overall energy output of a hurricane, it still generates vast amounts of power: around 1.5 terawatts, or just over a quarter of the world’s current total electrical generating capacity of 5.25 terawatts. > > > What happens when an underwater volcano dumps [1-2TW](https://www.nature.com/articles/s41467-021-22439-y) in the ocean - megaplumes dispersing ashes over 10–150km3 areas. --- Bottom line, just forget about the magic, the nature is way more than your magic can imagine. [Answer] **I assume you're asking, "what happens when the magic runs out?"** Your island is maintained by magical means. Therefore, the only weather patterns inside the limit of the magic is what is defined by the magic. Paradise. Wonderful! Outside that magical limit we have standard polar behavior. Bears. Days that are six months long (give or take). Cold. Bears. Occasional seals and some left over equipment from various expeditions to the pole that got lost. I mentioned bears.... The only question that makes sense here is, what happens at the *interface* between those two worlds? For some insight, let's turn to the [good folks at Britannica](https://www.britannica.com/video/143206/Weather-interaction-movement-temperatures-air-masses) > > Air masses are gigantic atmospheric volumes with very specific temperature and humidity characteristics. When two different air masses come into contact, they don't mix. They push against each other along a line called a front. When a warm air mass meets a cold air mass, the warm air rises since it is lighter. At high altitude it cools, and the water vapor it contains condenses. This type of front is called a warm front. It generates nimbostratus clouds, which can result in moderate rain. On the other hand, when a cold air mass catches up with a warm air mass, the cold air slides under the warm air and pushes it upward. As it rises, the warm air cools rapidly. This configuration, called a cold front, gives rise to cumulonimbus clouds, often associated with heavy precipitation and storms. > > > As air masses move, pushed by winds, they directly influence the weather in the regions over which they pass. In this way, they help to circulate heat and humidity in the atmosphere. > > > This is your classic problem of an immovable object (your magic) meeting an unstoppable force (the polar climate). What do you get? ***Storms.*** What are you probably going to get? *A permanent [Arctic Cyclone](https://hypotheticalhurricanes.fandom.com/wiki/Arctic_Cyclone).* So, the denizens of your island would have a lovely view straight up. But in all other directions, it would be a bit like being on the [Truman Show](https://en.wikipedia.org/wiki/The_Truman_Show) from the inside. ]
[Question] [ Could someone with textile knowledge share the wisdom and tell me what type of fiber for clothing different cultures should use or are best suited to use based on their climate and needs? I know jute, sisal and kenaf are really tough but uncomfortable fibers, mostly used for non-clothing things but with heavy processing it can be turned into soft and smooth cloth...but then again is the heavy processing viable and worth over just growing softer and smoother fibers? I don't know, but I guess not... [Answer] **Why wear clothing at all?** Always consider the option of wearing nothing at all apart from decorative bits & bling and protective gear. Clothing, for the vast majority of the human race, is a matter of culture not biology. (Consider that Tierra del Fuegans traditionally got along pretty well stark naked in a subpolar climate -- yeah, they evolved!) Considering that civilisations always seem to have evolved in relatively warm & temperate climates, there's no good reason why people must wear clothing. Consider the needs your civilisations' peoples have: * **decoration** --- a decorative scarf or a jaunty sarong or perhaps some well placed body paint might be all that's needed for the day's activities. Mix and match with some bead strings or gold bangles and well dressed might mean not dressed at all! * **sensible protection** --- work gloves, a codpiece and perhaps some boots might be nice for building a house or working in a smithy; a surgical gown and mask would be real nice for medical procedures; but once the work is done, there's no reason to wear the surgical gown out of the hospital or the codpiece and heavy apron out of the smithy! Clothing to meet the needs of work or occupation is common sense! * **other than that** --- what's the point your culture is making by wearing clothing in the first place? --- **On pockets:** pockets are indeed useful!, but are a relatively new invention ([1600s or thereabouts](https://en.wikipedia.org/wiki/Pocket)). Before that time, people wore belts to which they could attach a purse or pocket. The word "pocket" literally means a little bag, just as a "poke" means a big bag or a sack. Such pockets can also be attached to a bandolier or even slung from a string around one's neck. [Answer] Since your question does not provide many details of your world, I will focus on **general principles that can be used to develop clothing for your project**. These five factors will influence clothing and its styles (in order of importance): 1. Climate Climate is the most decisive factor because some climates may require clothing and some not. For example, if your species live in zones that are too cold for them to survive without coverings, they will develop clothing. Likewise, if the climate is optimal (not too hot, not too cold, not too wet, not too dry, etc.) there may be no need for clothing at all and it will not appear. Climate also informs what types of fabric to use and how to wear clothing. For example, it is advisable to wear [layered clothing (to trap air between layers) in the extreme cold](https://www.wikiwand.com/en/Extreme_cold_weather_clothing). Similar considerations should be made for [hot](https://www.popsci.com/diy/hot-weather-clothing/) [weather](https://www.npr.org/2012/07/25/157302810/summer-science-clothes-keep-you-cool-more-or-less). Apparently, [colour does not matter for hot weather](https://science.howstuffworks.com/science-vs-myth/everyday-myths/light-colored-clothes-in-hot-weather.htm), but [weave (weight of the fabric and its pattern) and cut (loose or tight-fitting clothes) do](https://gizmodo.com/the-physics-that-explain-why-you-should-wear-black-this-5903956) (I vaguely remember that I read somewhere that black-white summer clothing debate is complicated and the best colour and style combination depends on wearer being in shade or exposed to direct sun, humidity, and the presence of wind. Unfortunately, I cannot find the link.). 2. Technology The technological level determines what materials are available and how they can be processed. For example, pre-industrial societies will have access only to natural materials (plant fibre, leather, fur, and alike) while technologically developed societies may be able to produce synthetic fibres (polyester, nylon, and alike). Technological level affects types of available fabrics. Fabrics can be [woven](https://www.textileschool.com/246/basics-weaving-woven-fabrics/), [knitted](https://www.textileschool.com/251/knitted-fabrics-and-types/), or [non-woven](https://www.textileschool.com/352/non-woven-fabrics/). In addition to different manufacturing processes fabrics can have [different patterns](https://www.textileschool.com/171/textile-fabric-types-comprehensive-list-of-textile-fabrics/) which are dependent on available technologies. For example, [brocades](https://www.wikiwand.com/en/Brocade) require rather advanced looms. Processing goes beyond fabric creation. It also includes clothing-making techniques. For example, [corsets](https://www.wikiwand.com/en/Corset) are impossible in Stone Age (they require knowledge of specialised measuring, cutting, and sewing techniques in addition to special fabrics and sewing notions like corset ribs). Another important aspect is that most of the clothing in the pre-industrial world was tailored to individuals (as opposed to the prevalence of ready-to-wear garments of today). [One of the first mass-produced clothes](https://www.masterclass.com/articles/ready-to-wear-fashion-guide#what-is-readytowear) were military uniforms (1812). Technology will also affect dyeing, embellishments, and accessories. For example, many lighter shades of blue would be very expensive and/or unavailable in pre-industrial societies. Embellishments are decorative elements such as embroidery, lace, frills, ribbons, buttons, and so on. [Buttons](https://www.wikiwand.com/en/Button) are easy to make and they appeared very early in history. However, they became functional only in the 13th century. Accessories will reflect everyday needs and habits. (Take a look at [these stunning lice combs](https://www.atlasobscura.com/articles/some-of-historys-most-beautiful-combs-were-made-for-lice-removal)!) 3. Available materials Availability of materials depends on climate and technology. Here is [the list of the most used fibres](https://www.textileschool.com/2782/comprehensive-list-of-textile-fibers/) in our world and [another list](https://www.textileschool.com/3026/textile-fabric-types-by-fiber-sources/) of fabrics made of these fibres and their properties. If I am not mistaken, historically the most used materials were fur, leather, wool, flax (linen), hemp, cotton, and silk. You can start with the [history of clothing and textile](https://www.wikiwand.com/en/History_of_clothing_and_textiles) to see specific examples of uses and styles. There are also some rare exotic materials like [sea silk](https://www.wikiwand.com/en/Sea_silk). They can be used to make items displaying high status, e.g. Emperor's robes. 4. Culture and Society Culture, social norms, and local laws and traditions will dictate styles more than anything else. However, they may also restrict the use of specific fabrics or materials. For example, there can be luxury laws that prohibit the use of expensive garments (rare fabrics, jewels, gold and silver threads, etc.) by the lower classes. It is important to remember that while culture and society may have lots of weird requirements for garments, the utility will be rarely compromised. Nobility may use very restrictive and impractical clothing but these cumbersome outfits serve a purpose -- to demonstrate the high social status. Peasant clothing (excluding garments for special occasions like weddings, funerals, and various celebrations) will always be practical and adapted to the local climate and predominant activities. 5. Trade No trade means that only local materials and technologies will be used. Styles will also be very homogenous and change slowly. Fast fashion is only possible in a globalised industrialised world where garments can be manufactured cheaply and fast. Historically clothing was not cheap and many items were passed down from one family member to another. If trade exists, trade hubs will have a wider range of styles and fabrics. Remote and poor regions may not be affected if the trade is chiefly focused on luxury items. However, it is also possible that cheap fibres or clothes will be imported and become the common choice for the lower classes (as it is now with cheap clothing and fabrics imported to Europe and North America from less developed countries). Imported materials also can fully replace local materials if they are sufficiently cheap and abundant (this is less likely to happen in societies at low technological levels). [Answer] **Firstly they will use whatever is available. Secondly they will trade or explore for better materials.** Without trade or expeditions there is limited ability to select suitable materials. In a non-trading or primitive culture the materials in use will be restricted according to 1: Whatever raw material is immediately available in the local area. 2: The skills of the local population. For example a cave man living in a palm forest might just tie a palm leaf around his waist to cover his crotch. A more advanced culture might weave a skirt out of dried palm leaves. A yet more advanced culture might spin the leaves into threads and use the threads for knitting jumpers. These would still be rough but you get the idea, they have to devise materials using whatever is on hand so in order to know what clothing materials a primitive culture would be using you have to think about what environment they are trying to survive in, what raw materials they would have access to, and how advanced they are. People living in arctic tundra might not have access to any significant plants and are more likely to wear animal skins from the animals they kill for food. People living in hot tropical paradises might not be motivated to use clothing at all. People living in regions with populations of fluffy goats would be very lucky. If trade is available then this completely changes the picture - we know that ancient cultures traded with each other to secure products and materials which were not available locally, going to incredible lengths to secure high quality fabrics. As long as trade is available then a single advanced culture would be able to make these products available to a great many less advanced cultures. Consider China supplying silk products to medeival Europe, one "China" would potentially be enough to ensure that everyone in the world had the option of buying a shirt even if it were expensive, it could also serve as inspiration for developing those skills locally. In regards to your last comment - in my opinion someone who has been forced to wear a winter jumper made out of what is essentially tow rope would be highly motivated to find an alternative solution and might dedicate a significant portion of their life to finding that solution. It is possible that some cultures do not have the concept of explore or trade, but if they do then for a primitive culture in a harsh or temperate climate once reliable firemaking and shelter have been achieved, I think finding better fabrics would be an ongoing project. A primitive culture of a hundred or so individuals would be in the position to mount exploratory expeditions to locate say sheep, goats, cotton plants, or other things suitable for threadmaking - once the principle of "soft is good" has been understood then they would be able to identify potentially suitable materials visually and by touch. This might even be the motivation for a non-trading culture to become a trading culture (imagine once again the long winter evenings spent itching in your palm-rope jumper and the long winter days spent tending to the wounds caused by your palm-rope jumper). This all depends on where you want to go with the development of the culture - what they would be using is closely linked to other aspects of their culture - skills, areas known, willingness to trade and with whom, ability to explore, ingenuity, morality/religion (will they kill animals for fur?), agricultiral ability for growing jute or cotton, labour model (do the children and women stay at home and spin threads all day whilst the men chuck spears at the neighbouring tribe?) and probably many other things. Edit: I realise this is a very general answer, the question is too broad to answer specifically but I think that applying general principles like this will allow for a decent level of realism - if you really flesh out your culture(s) then the type of materials they would use should become apparent. [Answer] There are a lot of possible variables here, so I'm going with only the most versatile options. **Flax. Definitely flax.** It grows across the world from New Zealand to Europe (and it grows fine in the Americas, once it was introduced), it's been used since 30,000 BC and selectively bred for specific features as early as 7,000 BC, and it makes linen soft enough to make underwear out of. It was still in use across the globe until cotton became cheap in the 1900s. For armor and other protective uses like thick gloves for heat protection, flax linen can also be layered and quilted to make gambeson, one of or perhaps the most widespread armor used across Europe in the middle ages, being much easier and cheaper to make than anything else (leather armor was surprisingly uncommon, for reasons outside the scope of this answer). Armor similar to gambeson has been made by many cultures throughout the ages. **Wool** is still a common material in clothing, and was even more so in centuries past. It can be made into armor like gambeson, or coats, scarfs, shirts, socks, just about everything. **Cotton** could obviously be used if the society has access to it. Both flax linen and cotton can be used to make **cambric**, a common material in European clothing for periods of the middle ages. And **silk** is an option, of course, provided they can learn to make it. Everything I **bolded** can be easily researched for more details, with comprehensive Wikipedia articles about each to get you started. ]
[Question] [ The other day I wrote [this](https://worldbuilding.stackexchange.com/q/205154/86045) post, asking about the possibility of an electricity based weapon. Sadly, no real feasible or possible weapon was available that could work in a vacuum with some actual effectiveness, so I've mostly dropped the idea. I'm still persistent though, looking for viable alternatives or lesser known weapons that differ from the typical lasers, torpedoes/missiles, and railguns that dominate more typical space warfare. The reason behind this is simply that the same old weapons used over and over again can get boring and repetitive, with the exception of missiles. Lasers and railguns can just end up being so basic in what they have the capability to do, and limited flexibility. Essentially, what I'm looking for in this post is **other weapons besides the typical lasers and railguns.** They don't necessarily need to be flashy, or more effective, just weapons that can have some effect and not be ludicrously expensive or weak. As I said in the post title, I have a few ideas already, specifically ETCs as a possible alternative to railguns, and macron accelerators due to them being a possible alternative to lasers. ETCs use typical gun propellants, except light things more equally and can achieve faster muzzle velocities. Macron accelerators, I'll be blunt in the fact that I don't really know how they work, but they're explained well [here.](https://toughsf.blogspot.com/2019/11/hypervelocity-macron-accelerators.html#more) Some other ideas I had ranged from plasma weapon ideas like MARAUDER to possible missile/torpedo projectiles that use nuclear pulse propulsion to reach high speeds. There are relatively little guidelines to alternative weapons, but the few there are are listed below: 1. Must be capable of working in space. This is an obvious one. 2. Must be efficient to an extent. This means that it can't cost trillions, and it can't use ludicrous amounts of materials. Power consumption isn't as much of an issue. 3. Must have at least a minor amount of science basis. It doesn't need tons of hard science or realism, but it can't use tons of handwaving or magic materials. 4. Assume that possible problems like recoil aren't as much of an issue. I look forward to any responses! And feel free to give feedback on my post if needed so that I can revise it and make it better. To reiterate, I'm essentially looking for **alternative weapons to spice up space warfare.** [Answer] **MASERS** Beam weapons, very similar to lasers, except they use radio-frequency waves instead of light. The only real difference is that making the beam is done somewhat differently, and due to the different frequency of the beam, it has different characteristics. Notably, a Maser may be able to penetrate things like gas clouds or other thin material that are transparent to microwave frequencies. **NUCLEAR PASTA/MATTER COMPRESSION WARHEADS** It is theorized that an ultra-dense, degenerate form of matter can be found inside the core of neutron stars. This matter, called ["Nuclear Pasta"](https://en.wikipedia.org/wiki/Nuclear_pasta) likely has some extremely exotic properties if it could be artificially created and contained. Even without reaching these extreme densities, it is likely that advanced technology could squeeze more matter into less volume (matter is mostly empty after all). Doing so could result in some rather neat warheads, with the ability to outstrip the efficacy of even uncompressed nuclear- or antimatter- bombs. **PARTICLE ACCELERATORS** Essentially still a kinetic weapon, this type relies on accelerating particles to very high speeds (but still sub-c). How this is done and what type of matter is accelerated is up to the user. Ions or other charged particles would probably be the simplest, as their electric field makes it easy to push them around, but the ultimate version of this weapon would be to use anti-matter or anti-ions. This would be extremely dangerous, and only work in space since due to the vacuum. **NUCLEAR PUMPED LASER** You already mentioned lasers, but I think this specific design is unique enough to deserve a mention. Essentially, it's creating a powerful x-ray laser beam by detonating a nuclear weapon and focusing it by directing it through a long rod of metal. This was actually seriously considered and researched in Regan's "Star Wars" program, specifically "[Project Excalibur](https://en.wikipedia.org/wiki/Project_Excalibur)". In this project, an orbital nuclear weapon would be surrounded by a shell of aimable rods, and when a soviet nuclear launch was detected, the device would detonate, generating up to 50 powerful x-ray laser pulses aimed at any warheads and missiles. **GREY GOO DISPENSERS** This is a rather slow and stealthy weapon, but self-replicating micro- or nano-scale machines could be fired at the enemy ship in a cloud. It wouldn't deal any immediate damage, but be very hard to dodge (due to the big cloud) and very difficult to block. Once the miniature machines latch on to the enemy ship's hull, they start eating it and replicating. If not dealt with, eventually this would cause hull breaches, and then failures in ship structural integrity. **EMP/RADIOLOGICAL WEAPONS** By constructing bombs that are essentially nuclear shaped explosives, you could direct a large burst of radiation conically at a target. This could be an interesting weapon, because depending on the wavelength of the radiation, you could achieve different effects. For example, you could tune the system so that it doses biological beings with lethal amounts of radiation but leaves the ship (mostly) intact, allowing salvage or easy recycling. Unfortunately though, ships are likely to have heavy shielding against radiation, as this is already one of the main hazards to biological beings in space. **BETTER MISSILE WARHEADS** You already mentioned missiles/torpedoes in your question, but I think there's still a lot of flexibility here to spice up space combat, notably by adding nuclear power and more diverse warheads. For example, you could have nuclear shotgun torpedoes, which, when within range of the target (a couple thousand km or so), detonate and shoot a dense cluster of fragments at the ship. Similarly, a nuclear HEAT round would be able to shoot a high-speed compressed beam of super-heated liquid tungsten at a ship from many km away. In fact, missiles that can deal damage before they strike the target are probably better than simple explode-on-impact systems because nuclear explosions, even at close ranges, aren't super dangerous in a vacuum because they have nothing to push against. [Answer] **Use the same old, but differently** What seems to be the worst for you is that a lot of weapons are the same old. The thing is, many can be used in surprising ways, allowing you to be incredibly creative with the same old stuff. Lasers have a huge range of effects possible. They can heat, ablate, accelerate, change composition, localised freezing and more. It really depends on what form of laser you use. But a railgun is much the same. You might think a payload going at such high speeds is advantageous, as a solid round has incredible energies. A normal bullet can potentially be fired so hard it'll impact like a grenade! But that can actually be detrimental. An AP bullet against an unarmoured target is bad, as it'll straight up penetrate the body and come out the other side, not imparting most of it's energy and a higher chance of not doing enough damage. A railgun might punch straight through, but not do enough damage on the way. You can then start messing with the bullet, firing magnetic gasses instead, or have special payloads inside the bullet for extra effects. The payload can be akin to a battery, possibly charged in part by the magnetic forces, allowing a transfer of lightning when it touches the ship. You do need to pack an insane amount of energy in a relatively small package for lightning as powerful as in nature, but in general you can already make pretty effective lightning from smaller charges. In general my answer is to say you can use the existing, but use it differently. This can be because most literature isn't true enough to form, or there's tertiary reasons to use different kinds of interesting payloads. [Answer] I think a collimated neutral particle beam is probably the best possible possible weapon if you disregard exactly how to produce the beam (I doubt it would be very energy efficient compared to a relativistic railgun). It combines the best properties of mass drivers/rail guns and lasers, in that it's non dispersive over basically any reasonable range (unlike a laser) and it's travel time is basically c (unlike most railguns). Charged particle beams are almost the worst thing you could use because the beam is incredibly dispersive, and they can be deflected with electric or magnetic fields. The precision of a neutral particle beam this is basically limited by the quality of the targeting data available, and your capacity to direct the beam. The intrinsic capacity for precision of neutral particle beam is so good one could make a headshot from the Earth to Mars. Over 2 au, a 1 meter aperture neutron beam has a spot size of about a cm, it gets even better with atoms, but you may have more penetration issues if the target is shielded. And I haven't even discussed the fact that, depending on the neutron flux, anything the beam hits will have have a fast neutron reaction, neatly obliterating anything nearby in a nuclear fireball. For extra cool factor the beam will glow blue from cherenkov radiation in atmosphere. The ideal setup might be a relativistic rail gun for slow targets like planets and stations, combined with one of these beams for precision strikes and when you just need that extra few 9s on the end of terminal velocity (0.999... c). [Answer] # Wormhole Torpedos Similar to a normal torpedo on the outside, these weapons contain a small and unstable wormhole fragment in a quantum containment vessel. On impact, the containment breaches, and the wormhole surges out of control before dissipating. Everything within 5-70 meters (depending on the size of the fragment) is then warped to the other end of the wormhole. This inflicts fairly substantial damage on enemy ships, but the other end of the wormhole is also a salvage yard, so the materials stripped from the enemy can be recycled into new ships. In some cases, a larger torpedo and a lucky shot can even claim working equipment. Additionally the torpedos can take the place of an escape pod in an emergency. Just put on a space suit, get within range of the warhead, and get sent back to friendly space and picked up by a salvage crew. *Not sure if this is realistic/sciency enough, but I can't recall seeing anything like it before.* [Answer] I love the macaroon accelerator! And now I am hungry. I also have some other ideas for weird weapons: 1. **Strange matter.** Not super novel but not rehashed lasers and rockets. Strange matter is a form of quark matter that is not like our familiar baryonic matter. It is possible that strange matter could be "infectious" converting our familiar matter into strange matter. [Is there any guidance how my matter from another universe should behave?](https://worldbuilding.stackexchange.com/questions/179105/is-there-any-guidance-how-my-matter-from-another-universe-should-behave/179108#179108) 2. **Glueballs.** <https://en.wikipedia.org/wiki/Glueball> These are agglomerations of gluons, the particles which mediate the strong force that holds matter together. <https://en.wikipedia.org/wiki/Gluon> > > A gluon (/ˈɡluːɒn/) is an elementary particle that acts as the > exchange particle (or gauge boson) for the strong force between > quarks. It is analogous to the exchange of photons in the > electromagnetic force between two charged particles.[6] In layman's > terms, they "glue" quarks together, forming hadrons such as protons > and neutrons. > > > Electrically neutral stabilized glueballs will disrupt the strong force, splitting atoms into constituent quarks. The result might be a quark-gluon plasma. <https://en.wikipedia.org/wiki/Quark%E2%80%93gluon_plasma> > > In short, a quark–gluon plasma flows like a splat of liquid, and > because it's not "transparent" with respect to quarks, it can > attenuate jets emitted by collisions. Furthermore, once formed, a ball > of quark–gluon plasma, like any hot object, transfers heat internally > by radiation. However, unlike in everyday objects, there is enough > energy available so that gluons (particles mediating the strong force) > collide and produce an excess of the heavy (i.e. high-energy) strange > quarks. Whereas, if the QGP didn't exist and there was a pure > collision, the same energy would be converted into a non-equilibrium > mixture containing even heavier quarks such as charm quarks or bottom > quarks.[34][35] > > > Matter of the target would be disrupted and changed - probably into a shower of exotic particles. But maybe other things. Quark-gluon plasma is heady stuff. 3. **Dimension shift.** We live in a multiverse of infinite parallel dimensions each one very similar to the next but not identical. With the correct vector it is possible to rotate the dimension of a given area of space and it requires very little energy. There is no defense against this except to not be in that area. It often turns out that the space rotated in is identical or nearly identical to what was there before and no harm is done. The corresponding space rotated in might be empty or very different or very weird. Or there may be only slight differences; for example on my ship that was hit, the bar now has a number of drinks I have never heard of and I would have heard. It is possible that large areas of the universe were so rotated in ancient battles, accounting for ...discrepancies. 4. **Ghost gun.** This weapon uses occult technomagical principles, more or less pulling an entity out of its plane and projecting it at enemies. Sometimes entities are identified, collected and stored in advance but storage is difficult and costly. More often the collection and projection occurs simultaneously and the nature of the projected entity is not known by the users of the weapon. Unless it comes back. Weapons of various makes collect a wide variety of entities and early versions often collected entities which were of no use as weapons, or were extremely dangerous, or incomplete, or all of the above. These weapons are a lot better now, the makers assure us. One must have purpose built technomagical defenses against such a weapon. [Answer] **Hacking** Make use of supply channel attacks, known communication protocol implementation bugs, etcetera to disable or destroy equipment in the enemy ships. This can be as simple as screwing up their aiming or navigation capability up to completely destroying their power source (and likely a large part of the ship with it). **Biological** Food supply contamination, pests or outright disease. This requires prior planning to get the agents on board but could be triggered by a signal when needed. **Social** Do a Hari Seldon/Foundation style attack where the attacker's fleet is withdrawn by their leader over suspicions about the loyalty of the admiral leading the attack. Another option would be to sow disinformation/dissention in the ranks of the attacking ships via deep faked sensory messages. **Financial** Destroy the economy or credit rating of the attacking empire or specific members of the command hierarchy. They'll beg you to let them surrender if you'll only restore their wealth. **MARD** Mutually assured relativistic destruction. Have self-assembling drones in the outskirts of the system that create relativistic kinetic weapons that can be aimed in any direction. It may take decades or more, but destruction of entire planetary surfaces can be done with little more than an encoded message specifying the target to the drones. **Temporal** So long as we're allowing interstellar war, we might as well admit that this requires FTL to be practical and therefore time travel. This can allow for many hilarious plot twists in attacks along the line of the above plus enemy ancestor murder! [Answer] **Muon gun** Muons are subatomic particles that are very hard to stop. You could use a beam of high energy muons to bypass armor and damage some systems aboard enemy warship. You don`t need a lot of energy to damage some electronics. **Monopoles** There might exist some topological defects such as monopoles. Such object would annihilate with anitmonopoles but not with normal mater. Same uses as antimatter but safer. **Nuclear Explosive Formed Projectiles** You could use nukes to accelerate multi-tone metal plates to multiple kilometers per second. Such a projectile could brake a ship in half with momentum that is carries. [Answer] Whilst this is far less practical or energy efficient, compared to many of the other weapons proposed. None the less here we go... **A "Gravity" weapon**. A weapon that would literally tear your enemies apart, as it would create massive tidal forces (which are differences in the gravitational "force" experiences by either end of your enemies station, ship, body, thus tearing it apart). And as it comes from distortions in space-time it can't be shielded from. **How would you make it:** tidal forces come from sharp distortions of space-time, this tends to happen very close to massive dense objects, (like black holes, where its called [Spaghettification](https://en.wikipedia.org/wiki/Spaghettification)). But black holes would be hard to create close to your enemies with out them noticing, and would be hard to clean up after the battle. Instead you could create the distortions by gravitational waves, as the also produce tidal forces as they pass [through a material](https://ned.ipac.caltech.edu/level5/ESSAYS/Boughn/boughn.html), and if strong enough would shred ships. Now is where the impracticality comes in, gravitational waves are emitted by large masses oscillating (technically the are also emitted from smaller masses as well, but they only emit lower amplitude waves). So to create a large distortion you would need a lot of mass (at least the mass of the sun), in a small volume (like a black hole, or neutron star). The current waves that have been observed com from black holes orbiting either another black hole or a neutron star, and emit the gravitational waves in a plane around the orbiting objects, so not that great for those around you. To get a more focused beam you might be able to get a series of black holes/neutron stars, arrayed correctly and oscillating at the right times, to produce a beam of gravitational waves directed at your enemies. It would be a massive weapon would require very advanced engineering to be able to arrange it correctly, but would be very destructive. Hopefully that helps [Answer] I personally do not like lasers for space combat settings, probably more because it is not enough space in the ways how they are usually described or used, but let's attack your perception that they are always boring. Dragongeek mentions nuclear-pumped laser, good stuff, buuut... ## Expand! Engage! Bigger! Better! Make it so! * make it soo big that u eyes are popping out from how big it is, space is big, keep your eyes in a pocket and fly safely. There are certain problems with the implementation of the idea, so it just an idea. Space is big and empty, very convenient for fusion things, I mean typical attempts to make fusion work spend a great deal of effort to make a vacuum close to one which is present in unlimited quantities in space. So imagine a gas(plasma) cloud (yes, I like gas clouds in space) in a form of a cylinder, with a diameter of 1-2 km and length of 1000 km. Which consist of some fusion mix maybe plus something, but not necessarily. If you manage to blast that cloud, ignite it in a fusion way, it will create a plasma cylinder, maybe 10 km in diameter in the time when it was used (obviously it will dissipate after a short time) but for a few milliseconds it is there for our use. It will be high energy plasma high excited state, it is what lasers use in their optical cavities so it is a thing which a laser needs, and a flash on one end in direction to another end will collect some energy, will be amplified by going through that plasma cloud and on the other end, as it exits the cloud it may have substantial energy. It does not need an optical cavity, a distance a photon goes bouncing forth and back in some 10cm rod is maybe a few times less than those 1000km soo straight through is enough. (Not enough? Make it 10'000, 100'000, a million km) ITER plasma energy/power density is something around 1MW per cubic meter of plasma, it is energy produced per second, soo let's say our plasma cloud exists, in its useful state shape form properties, for 5 ms, soo about 5000 J of energy per cubic meter are "produced" in those 5ms, let say the efficiency of extracting energy out of it with our amplified pulse is 1% (it probably should be more, but..), so we get 50J per cubic meter on the exit side. 2km diameter, 1000km length yields about 3 TJ of energy, contained in a 5ms pulse. * it 25 times more for that 10 km diameter I initially proposed. Why scaling down, idk, it is a complex dynamic expanding situation, so to be conservative Not much, especially compared to the size, and diameter of the beam, but it lands us in one kiloton of TNT territory for the pulse. And if we use a reactor on a ship to do the same it has to reach peak power of 600'000GW × 1/efficiency, or if we have some ability to pump the energy for a minute, and it sounds easier than it practically is as we have to store energy somewhere and at the end, we have to deliver it fast to some optical cavity then it is 50GW × 1/efficiency. * as of today, 50GW is quite a challenge and the thing isn't small, and if efficiency is 10% it then 500GW to shoot once in a minute. 500 reactors, eh. Thinking about that, a typical depiction of a laser installed in a ship is sooo wrong, sooo unrealistic from a technology perspective. In general, any high-energy weaponry or even devices or even the main characteristic of a space ship its engines installed next to crew and other ship internals is not necessarily the way to go. * The Expanse handwaved its Epstein drive, which by the specs is nothing but a regular fusion engine, but done in a right/wrong/realistic way then things would look nothing like it was depicted in the show, not even close. (Like their missiles, lol) * this expanse example probably is an addendum to the point - maybe things are boring because they are wrong and stuck to concepts of the 70's - weapons inside a ship, engine inside a ship, etc. Here a guy asked about heat dissipation for his ships, a right question [How to get rid of all the heat in my spaceship?](https://worldbuilding.stackexchange.com/questions/59402/how-to-get-rid-of-all-the-heat-in-my-spaceship/59484#59484) and the short answer is to not allow to build it up where it should not. And in that sense, external components are a perfect solution, engines, weaponry, and stuff. So a ship is not necessarily a ship as it was envisioned since the '70s as monohull construction but a cluster of components, deployed temporarily or always external. In the case of that plasma cloud, we have problems - it dissipates, how to ignite it, how to recharge, or how to set up it in the first place. In that sense, we can have a series of devices, in different configurations and function, not one solid block of a reactor of that size, but as separate units, like those cool stargate rings type every 1000 meters apart, which each of those we deploy out of cable/pipe/whatever 3.5-7 km long. These are, components, deployed from some ship, it is its external temporary device, which can have different stages of deployment for ease of manipulation with that equipment. And in the end, it is a somewhat open big fusion reactor that pulses for a minute(or how much it can take by design +50% to be more dramatic) each second making our 5 ms bangs, then some cooldown time, which can be speedup by some another deploy component. * that ring setup for that temporary fusion reactor is not necessarily the best way to do it, it can be a set of devices in its core as well(there are ways for that) and it may be a better way. But what best is probably beyond the point I try to conduct, and you were so generous with you restrictions soo * also magsail designs are quite interesting concepts of small devices affecting plasma, solar wind, at distances of 10's km. (There should be a link, but, someone plz) So instead of those useless carriers motherships which look so cool in the movies where main characters with cool faces jump in their fighters to do phue phue phue against bad guys. A ship deploys a unit that does the bang, which has the potential to obliterate things. With those fighter guys, especially on the distances and with those pointless actions they typically do, few nukes is enough to wipe them all clean, they were pointless since the inception. Some guy proposed to use sun's corona as the laser medium, no containing problem, should probably work well, obiviously it has its limitations as well. So really, more space thinking and things start to become fun again. What you typically see are old concepts reused over and over again because yeah you know reasons, lol. ## P.S. Where to get all those fusion components u waste so much each shot. Go to Jupiter, there is enough for hundreds of pan-solar wars. Okay okay maybe this laser thing isn't great in a long run, really worse than a steam engine, but imagine those guys from a fleet of carriers, they are about to do their pheu pheu usual stuff, and you enroll your shiny reactor thing for the first time for actions and bang bang, and then laugh at their debris muhaha, they even didn't have the time to deploy. This superiority will hold until the next good thing or until they build one for themselves, or effective countermeasures can be implemented. Countermeasures are inseparable from the capacities of your fleets, so you may figure out one quite fast(but that guess may turn out to be the wrong one) but not necessarily be able to implement, so it not instantaneous if one lacks capacities. There always will be a next good thing, nothing set in stone. ## P.P.S. In a sense your first question is good but not for an attacking purpose, but how to transmit energy in form of electricity in a compact way/easy to use directly between components in space which are km's apart without using wires. Those fancy plasma beams between components occasionally popping up, and they do make practical sense in some settings. ## P...S. That macron thing is quite good actually, you can use it to set up cloud, like dynamic 3d printing, D-icicle particles at different velocities and angles to melt and slowly to evaporate, and to ignite the cloud later. Soo, there is more than one way to skin a fish. [Answer] # Limpet mines An explosive device that waits for an enemy to draw near, then attaches itself to the hull before detonating. You could probably add other features: * Make it emit a bright EM signal to help your ship's sensors stay locked on the enemy, who is likely trying to minimize their sensor signature to confound your weapons. * Create sensor ghosts to confuse your enemy. * Make it wait to detonate until the enemy returns to base. You'd pretend to flee the engagement. Could also help track the enemy or locate their base, if that's an unknown. Mines are normally considered a bad idea in space because space is huge and empty[citation needed]. But consider that the enemy isn't interested in *all* space, they're interested in: * the space immediately around your vessel * the space where your vessel was * the space where your vessel will be * the space immediately around strategic or tactical locations * the space in and around your own wrecked vessels (derelicts) You don't have to surround the Earth with mines, which is good because it would take a bajillion of them. Instead, you may be able to create situations in which the enemy will *want* to draw near to the place where your mine is. Maybe that derelict was placed there. Maybe you're dishonorable and you sneak a mine onto the shuttle that the enemy uses to meet you for parlay. (You can't gain a bad reputation if everyone you stab in the back dies before they can report the fact.) I would hate to have mines as my *only* weapon, but it might not be a bad idea to carry a couple of them in case an opportunity presents itself. Worst-case, mines in your vessel could be rigged as a booby trap in case your crew are all killed and the enemy tries to board your ship. [Answer] Following Trioxidane's advice, let's give a second life to a railgun. ## Fusion cannon * I'll keep it short, more like a sketch of an idea Quite often people propose launching fuel canisters ahead of a ship for its interstellar journey, not going to work(only one case it can work) but here we can reshape it to a working idea. Let's imagine a million km long fusion fuel tube/gas cloud/icicles cloud which we deposited upfront the shoot. The projectile is a Bussard ramjet drive. It goes along the trace of that fuel, it moves along like a flame of a safety fuse. Compressing plasma in front, ionizing not yet plasma even further in front, and igniting plasma into fusion, and using exhaust as magsail device to propel itself. Advantages it may be a thing before you have good fusion reactors for the ships, as stability of plasma is not a problem for such construction, IMHO, because it ignites fuel as it goes and instabilities can't pass upfront and what happens at the tail no one cares. The diameter of that fusion fuse can be big, as usual, or small, but it harder. Can be used against more predictable targets, but projectile can be maneuvrable as well, chemical rockets, so it more like a cannon with smart shells. It is a constant acceleration projectile, no deacceleration capacities(so not appropriate for human use), no rocket equation. So let's say 10g for a million km it will be 140 km/s resulting speed, not much, so so, yeah probably need more than a million km, as million isn't that much it just 2.5 distances between earth-moon or higher acceleration. But still, it 12(24) days for a military response against Mars as an example. Not necessarily city destruction, but the potential to wipe all their satellites in orbit around Mars, disrupting communications and sure deliver some pressure. (Or is it a martian's plan, hm, hm) ]
[Question] [ The big bad vilain is stealing energy from our sun. He has been doing this for 2000 years and the sun has already shrunk in mass by 25%. What are the effects on our earth. From what i found [here](https://worldbuilding.stackexchange.com/questions/125953/can-the-sun-lose-enough-mass-that-saturns-current-velocity-becomes-escape-veloc) and [here](https://worldbuilding.stackexchange.com/questions/126018/how-do-you-non-catastrophically-reduce-the-mass-of-the-sun-by-half/126122#126122) I think earth should stay in orbit. But I was wondering how much this would affect the number of days in a year. [Answer] We can calculate the effect on Earth's orbit by applying conservation of angular momentum. Earth's orbital angular momentum is $$\ell=mvr=mr\sqrt{GM/r}=m\sqrt{GMr}$$ with $M$ the mass of the Sun, $m$ the mass of Earth, $v$ Earth's orbital velocity at any given point and $r$ the distance from Earth to the Sun at any given point. As angular momentum is a conserved quantity, and as the mass of *Earth* doesn't change, then $$Mr=\frac{\ell^2}{m^2G}$$ is *also* conserved. So before and after the Sun loses mass, $Mr$ is the same. We can then calculate the final semimajor axis of Earth: $$a\_f=\frac{M\_i}{M\_f}a\_i=\frac{1M\_{\odot}}{0.75M\_{\odot}}(1\text{ AU})=1.33\text{ AU}$$ We can also apply Kepler's third law to determine the period: $$P^2=\frac{4\pi^2}{GM}a^3$$ and plugging in the numbers gives us $P\approx1.78\text{ yrs}$, or around 650 days. Although you didn't ask explicitly about it in the question, we could consider what happens to Earth's [surface temperature](https://en.wikipedia.org/wiki/Effective_temperature#Surface_temperature_of_a_planet), which scales like $$T\_{\text{eff}}\propto\left(\frac{L}{a^2}\right)^{1/4}$$ where $L$ is the luminosity of the Sun. If $L$ doesn't change, then the temperature should decrease by about 14% - a bit too cold for my comfort. On the other hand, the luminosity certainly will decrease. Main sequence stars similar to the present-day Sun typical obey the mass-luminosity relation $L\propto M^{3.5}$, so naively inserting that above, we find that the new luminosity would be 37% of the Sun's present luminosity, leading to a true temperature drop of 33%, which would be quite awful. This is a bit unrealistic, but you'd certainly see the Sun cool and contract - and by enough to ensure that Earth is no longer in the habitable zone *as we know it*. Would there be any *major* changes, or will the Sun continue to operate as simply a less massive, cooler, smaller version of itself? I think the latter is likely. It would need to lose about 60% of its mass to become fully convective (the core is mostly radiative), and it would need to lose about 70% of its mass to never evolve onto the red giant branch. Its evolution would take longer - the time on the main sequence is roughly $\tau\propto L/M\propto M^{-2.5}$ - but it would follow a similar track. We won't see exotic fusion pathways or an unusual stellar remnant. Speaking of stellar evolution, the mass-loss part of this scenario is actually similar to what happens when a Sun-like star evolves onto the [asymptotic giant branch](https://en.wikipedia.org/wiki/Asymptotic_giant_branch) after spending time as a red giant. It should undergo mass loss on the order of $10^{-8}$ to $10^{-5}M\_{\odot}\text{ yr}^{-1}$, thanks to powerful stellar winds. In your case, the Sun loses mass at a rate of $10^{-4}M\_{\odot}\text{ yr}^{-1}$, which we do see in some extreme AGB stars. So purely in terms of mass loss, your villain is sort of accelerating the Sun's evolution dramatically - although of course it shouldn't trigger hydrogen shell burning outside the Sun's core, so it's not like the Sun will actually become an AGB star. It's simply going through a mass-loss phase like one. ]
[Question] [ Under normal circumstances, monolithic diamond is pretty terrible at resisting impact, due to it being weak in certain planes, also known as cleavage planes. To solve this, why don't we just make the diamonds smaller? They'd be much harder to hit on the cleavage plane that way (wink). What I had in mind was 10-20 micrometer diamond plates, arranged into a brickwork-like structure with an elastic polymer connecting them together. So, [nacre](https://en.wikipedia.org/wiki/Nacre#Structure_and_appearance) but made from nanodiamonds instead of calcium carbonate. Now, cleavage is present on the microscopic level (it arises from the "ideal" molecular structure of the crystal, not the deviations from it), so I don't know if it would work or if it would be better than boron carbide armor. **Would this diamond armor be able to resist firearms more effectively than either silicon carbide or boron carbide?** [Answer] You have just designed an armor which is an excellent abrasive: do you maybe want to polish your opponent? Just quoting from one of the many suppliers: > > [brand] flexible diamond coated discs combine the durability and aggressiveness of diamond, on a flexible backing. > > > The resistance of your armor with this material will be dictated by the resistance of the matrix, in this case the elastic polymer, which is not exactly the top notch. For a body armor to be effective against firearms you want something which can dissipate the kinetic energy of the bullet preventing it to be done by the body. Diamond won't help there, even in microsize. Generally speaking, when you make a composite material, when you add a material to a matrix, that material should provide some property which the matrix lacks. If you add diamond which is though but not resilient, you are adding toughness, that's why a polymer with added diamond makes a good abrasive but not a good armor. [Answer] We already have cheap bulletproof armors, you can buy a plate for less than than 100 dollars and a full suit of mixed carbon fiber and plates won't cost too much. The reason bullet proof armors can't get better than level 4 is because there's a point where it doesn't even matter how heavy and thick the armor you are wearing gets. A bullet fast enough will knock you off your feet and you'll get most of the damage from the impact on your liver,lungs, stomach, heart and bones. You can hide in a literal tank and use it as a shield, if the bullet is strong enough, it doesn't need to penetrate, the impact on the tank will throw you around and you will hit your head on the other walls of the tank. [Answer] **Bullet proof vest are effective because they dissipate energy, not because they are tough.** Toughness is the material's ability to resist being fractured. Lets say you have armor that is very tough but doesn't dissipate energy, like plate mail. That will stop most attacks, but eventually the attacks will break the toughness of the material and go straight through. Most bullets can do this to human sized armor. If the energy dissipates then the bullet needs more energy to move the vest more to have enough energy to break through. Because of this lighter weight polymers with good dispersion are preferred to tougher materials that don't disperse energy as well. However, you don't need every part of the vest to be strong enough to stop the bullet on its own, since the force is pushed over a larger area. If an average bullet exerts 1 kilonewtons and Kevlar is tough enough to withstand 2 kilonewtons of force exerted over it, making armor that can withstand 5 kilonewtons out of materials that don't dissipate as well isn't worth it. Both vests will survive, but one will dissipate worse and be more expensive of heavy. **Weight and safety concerns** Furthermore, Kevlar is half the density of diamond, with more tensile strength. Replacing Kevlar with diamond will increase the weight of the bullet proof jacket to potentially more that double its current weight. The armor could be cut down on weight reducing the dispersion even more, which would lead to other problems. Furthermore, with less dissipation the jacket will still cause more damage to the wearer as the same force is applied to the user over a smaller area. All in all, making armor tougher doesn't always make it better. [Answer] You need to dissipate kinetic energy to "stop" bullet. Diamonds, per sé, would only conserve and pass this energy to the armor user. (from its incompresible nature) I suggest to go to non-newtonian fluid, the very same that you could "walk on". Fist layer in diamond matrix, then several layer of this fluid. There are a lot of videos of this kind of bulletproof jacket on the web ]
[Question] [ Extrapolating ~10-20 years from our current technology, what are some limitations with 3-D printing? Is the ability to print any type of matter in reach, or are there some fundamental issues that might limit this technology? [Answer] So I've been 3D printing for nearly 2 decades so I feel I can extrapolate fairly well here. A lot has already been said but I'll just add: ### Dirt cheap printers requiring branded filaments: The cost of a machine will keep coming down (My first entry-level machine in 2005 was 2 weeks x Australian minimum wage. My most recent entry-level machine (2020) was 2 days x Australian minimum wage.), and, as people compare machines on price, you'll end up with machines sold at a loss but requiring overpriced filament. Similar to razor and blades / 2d printer and inks. So a limitation of home / hobbyist machines in the future will be they need manufacturer approved filament - with the microchip in the roll to validate it. You can of course pay a premium to side-step this with an expensive printer, get hacked filament, or build a printer yourself from parts, but how many people today build their own 2D printer to get around the overpriced ink? ### Positional accuracy imperfections. Subtle amounts of slack in the belts, morphing of the guide rails, twisting of the build plate, etc limit how accurately the head can be positioned. My best printer can position itself to 0.002mm electronically but realistically it's off by about 0.05mm minimum (0.5mm if I haven't calibrated it in the last few days). 20 years in the future a home machine may knock another zero off that but it's still not accurate enough for printing say, a computer chip, which needs ~0.0001mm accuracy or better. ### You're going to have to service it still. They will still be susceptible to jams in some form (a common one is material expanding in the tube from heat and blocking it). Every few months minimum you'll need to clear a clog of some form. It'll be an improvement from today (my 5 machines are running 247 and every week I need to service at least one). This may become a service done by a profesional, like a car mechanic. Expect a counter on the machine saying "Oh you've printed 200kg of plastic - due for a service!" ### Tiny layer imperfections wont go away It will still have tiny layer variations, mostly due to subtle differences in material flow rate. A common cause now is temperature variation and back pressure causing skips (the extruder cant push the material fast enough so there's less material in an area than expected). These may be mitigated by sensors either detecting the abnormal flow or scanning the model after each layer and retouching, but there will be some blemishes from the skips and slips of the extruder and tiny variations in filament width. As already mentioned, you wont be printing a transparent plexiglass plane anytime soon. ### Will still need some post processing Prints will still suffer stringing (where tiny trails of molten material leave the model footprint like molten cheese from a pizza) and pimples (where tiny extra bits of material accumulate on the head and merge with the surface later). These will require post processing. Upper end machines will be able to assist with this but no 3d printing a ventilator and connecting it straight to a patient without tiny bits of plastic hairs getting into their lungs. In the early stages of covid19 I was working with other home hobbyists printing health supplies as needed, and most of the home printing tech could only do PPE (eg face shield mounting bands). Only one of my printers Resin SLA tech) was able to do ventilator parts due to concerns about stringing tiny microfibres. ### Fault lines and non-uniform strength. Prints will still have fault lines. Even with a multi-axis rotating base plate allowing the z axis to pivot in multiple directions to mitigate this, there still will still be weakness between the layers, I think we can get to the point that so it isn't a series of straight lines in the z plane, but the fault lines between layers will still be there as a weak point. I can already 3D print things that can hold my own body weight (handles / straps / steps / etc), but I'm not going to be 3D printing my own carabiner and climbing a mountain with it. ### Fire proofing. As someone who 3d prints and fire dances I will never be able to 3d print my own fire dancing toys. If we need something to become stringy when hot to print at desktop temperatures, that will not be able to resist flame. Even the high temp resins and thermoset resins available in sla lose strength at like 110 degrees. In a few decades this will go up with new material tech, but we wont be able to achieve strength under fire yet melt when required for forming in a machine on my desk. ### Government restrictions on materials Greenwashing efforts will apply some legal limitations. With concerns about the ocean becoming plasticised and jurisdictions banning plastics straws and cutlery (instead of banning the more substantial fishing nets and plastic packaging), expect the "home novelty plastic figurine creation" industry to take some legal hits. Expect some government bans on useful filaments in a misguided effort to cut down on pollution. ### Expect laws regarding plastic labeling on home prints. In addition to government banning useful filaments, expect government legislation on labeling prints. PLA filament can be trivially recycled (or composted), but it shouldn't be mixed with other plastics in the recycling plant in any decent volume as it can degrade the final product, and if output plastic is inferior, it can't be sold, making recycling unviable. Expect to print the little chasing arrows with a number on the base of all prints, from cute figurines to machine parts. It may even be done automatically by the firmware. ### Expect 'Taggants' in high strength filaments to target 3D printable guns. How do you trace a 3D printed gun that's been used in a crime? The same way we trace explosives back from a bomb blast crime scene back to manufacturer / batch / invoice number. It's called Taggants, and [has been used successfully in prosecution of bomb cases](https://openjurist.org/713/f2d/57/united-states-v-l-mcfillin). Tiny microparticles encode bits of information allowing forensic investigators to identify the filament batch number by looking at the part under a microscope. So expect the FBI / etc to be able to trace 3D printed parts back to the sale of a batch number of a filament wholesale to at least the final retail outlet (where they case seize security footage / credit card receipts), perhaps even to the individual roll. I'd expect this to apply on any high-strength, high temp, filaments. Anything good enough you could use to make an automatic rifle out of minimum. ### Expect DRM People will start selling their creations online as 3d-printable as an alternative to shipping it. However to limit the propagation of copies, expect that design to be licensed to your printer only, and only available to print for a limited window. So of course when a printer dies, or a manufacturer goes bust, or a hard drive dies, or you forget the password, or you just have an off-brand printer, you won't be able to print something even if you have the design locally and paid for it. When a part breaks after the warranty period, DRM will prevent you from reprinting it, you'll have to buy the rights to print another one. --- ### Aside - expect society to change tastes to geometry that can be 3D printed. Rather than a technical limitation stopping people from printing their dreams, I expect society will (in some cases) change their dreams to the technical limitations. Which furniture company do you expect to remain in business in 20 years? * The one making furniture in some 3rd world country on the cheap and shipping it to markets in shipping containers. * The one that has a big 3D printer out back and prints stock as it sells? Each retail store has one in stock of each design that, when it sells, a replacement is printed. Rather than keep warehouses of stock from cheap overseas manufacturers (and pay interest on all that finance), expect things to be printed just-in-time where possible. Because there are geometry requirements for 3D printing things (as detailed in the other answers so I wont repeat), the available products will change in line with that printing requirements, and tastes will change to follow. Every trendy apartment will be decorated with things that were 3D printed, and that distinct style will become common due to its economy. A table made from a big peice of wood will look clunky and obsolete in 20 years when compared to the modern, 3D printed on demand furniture. (Or even cheaper idea: A furniture store only has display stock. When you order, they drive a trailer to your house and plop it in your driveway for a few hours / overnight. The new chest of drawers you ordered is printed on your property, they come back, unload it for you, and take the trailer to the next customer.). [Answer] **Predicting 20 years into the future is incredibly hard** Let me begin with a disclaimer. 99.99% of the technology we enjoy today was invented in the last 150 years. Twenty years ago (2,000ish), the era of Palm Pilots, the idea of fully-graphical hand-held computers was still very much the domain of Star Trek and the flat screen monitors that are a part of our everyday life were only just hitting the commercial market — most of us were still using CRT monitors and televisions. Twenty years is technologically *forever.* **Therefore, the only limitations I can reasonably predict are (a) geometric and (b) mechanical** * 3D printing will always have problems with geometry. For example, 3D printing a can for spray paint will have trouble with the marble inside the can, which must be entirely detached to operate. The same could be said for bearing assemblies. And those are just the easy-to-grasp examples. 3D printing describes the *result,* not the *process.* The process is very much 2D in nature. * 3D printing will also be limited by the number of materials that can be brought to bear. Printing an entire car as we understand them today would mean printing multiple kinds of metals, plastics, ceramics, textiles... This is primarily an issue of practicality as, perhaps, one could imagine bringing different print heads to bear at different times to build things... but that brings us back to the issue of geometry. The window in the car door has a bolt through it. How do you keep the glass in place while you shift back-and-forth between print heads to lay down the metal of the bolt? How do you keep it all in place in the first place? But I digress... * Another limitation is anything having multiple pressures. Let's go back to that spray paint can. What if we try to 3D print the entire, finished can? That means we're trying to lay down pressurized paint at the same time we print unpressurized metal. Theoretically, in this case, we could pressurize the entire print space ... but what if you needed two propellants at different pressures? * The size of the print space will always be an issue. This might be more an issue of economics than anything else, but it seems that the ability to print a microchip in the space needed to build a dump truck would rarely make sense. It would be faster to have one printer to print the control electronics and another to print larger components then assemble. But, you will always be limited by the size of the print space. The support bars needed to hold the print heads and transport the printing medium would need to be fantastically strong to accurately print a 747 airplane. (And we're back to that first bullet... good luck printing the tires and wheel assemblies in-situ.) Support bar sag will probably always be a significant limitation (limiting the size of what can be printed). * Finally, 3D printing will always be limited by what can be made a liquid within acceptable conditions. 3D printing with molten steel will likely never make sense. It's why most 3D printing today is done with, basically, glue. It anneals to what's already there and hardens almost instantaneously. Few materials can be worked with in that way. In fact, anything that requires tempering (like tempered steel) would intrinsically limit what can be printed at one time (if at all). *It's worth noting that while it's tempting to see 3D printing as morphing into something akin to Star Trek replicators, they won't actually do that. To me, 3D printing feels like a "cul-de-sac technology." A cul-de-sac technology is one that is either necessary or, at least, obvious in hindsight to the development of technology as a whole — but in and of itself, the branch of technology doesn't go anywhere. It could be said that all technologies are intrinsically cul-de-sac technologies (telephone land lines are a good example), but some are very short-lived. [Palm Pilots](https://en.wikipedia.org/wiki/PalmPilot), for example.... My gut tells me today's 3D printing will morph into something on an industrial scale that will be a hybrid of technologies — and I wish I knew what... I'd make billions....* [Answer] JBH does a great job covering the limitations of geometry so I will just add a few things. Printing metal is severely hampered by the fact iron based metal end up brittle since they can't be properly forged or tempered. so don't expect 3d printing of steel for anything structural. Anything that must be altered after the fact will be out, so no vulcanized rubber, this applies doubly so for anything reactive like a battery. The same goes for things that need to be uniformly transparent like phone screens. 3D printing can't lay down a uniform sheet of material without being made only for that. Don't expect 1 unit to do everything. you will need different printers for drastically different materials, the machine that makes leather will not be making dishwasher parts. Expect big improvements of 3D printing of biological materials like food or tissue, They are already being developed, it needs a lot of things worked out but there is no hard barriers. expect 3D printed organs and transplant tissue. They may not be perfect but they are much better than the alternative, especially if you make them from your own cells, don't expect this at home however, this will be something that gets done in specialized hospitals. Expect 3D printed foods. Do not expect things that are largely unprocessed like steak or fruit, although vat grown steak may become common and this may start as 3D printed precursor. Some things will still have to be cooked afterwards, you can 3D print a cake but you have to bake it afterwards. Chemistry might even let us custom make more complex biological molecules from simple ones although 20 years might be too soon for that. Expect 3D printed leather, its already in the works, printed and woven cloth would not surprise me either. So you could have a home machine that makes custom clothes. Although the machine will have to do more than just print. Expect 3D printed home made circuitry. they may not be quite as good as normal circuits but the on demand customization ability will more than make up for it. Home made electronics will explode in popularity. buy a bespoke laptop. Expect integration with other technology, micro-shops are combination 3D printing and CNC machines that can do things neither one by itself can do. Medical tissue printers may include gene sequencer, protein sequencers, and incubators. Lastly expect a term to preplace "3D printed", something simpler or shorter. The more common a technology becomes the shorter its name tends to get. [Answer] **3D printing will become a daily tool for construction specialists/handymen.** It is inevitable that 3d printing will: * Produce prints faster * Print stronger materials * Become easier to use Once the technology reaches the level where a fist-sized part can be printed in under an hour, it will revolutionize the way that various "handymen" or construction specialists do their work. For example, right now, a plumber needs to have the back of their van full of every conceivable pipe fitting so that they can minimize shopping runs and order delays. If, for example, they arrive at a customer and that customer has an oddball pipe fitting somewhere, there is no way for the plumber to simply improvise a fit--they have to measure, order the part, and then come back to install it. With a fast 3d printer, the plumber could simply say, "I need a 7/8ths to 1 3/8ths male to male adapter with a 90 degree bend" and half an hour later, the part is printed and ready to install. Similarly, repair technicians of all flavors could do their jobs much quicker if they could just punch in the serial number for a specific device--say a washing machine--and then print the exact part needed to repair it. Of course, the manufacturer would probably extract a licensing fee for the service, but it's better than ordering and waiting forever to get a small plastic do-dad which only takes a couple minutes to print. ]
[Question] [ I want to create a sapient, amphibious species who have developed a civilization around as advanced as late bronze age Egypt and the Middle East. I would want to know if these sapient amphibians could be able to develop metallurgy or if their skin would be too sensitive to heat to smelt metals. [Answer] If they can manage being around fire metallurgy won't be much more dangerous than staying close to a fire. In our own development, we have managed to control fire way before reaching the bronze age, already in the stone age, and that's probably what kicked us on the sapience way. And our skin is not that sturdier when it comes to handling radiant heat or spillage of molten metal. As long they find a way to keep it moist, they will find a way. On a side note, one can get somehow used staying close to hot surfaces or flames: ask most of the moms or cooks who spend their time cooking. [Answer] **They absolutely could.** Let's assume we are talking about something like an anthropomorphic amphibian, meaning something that is anatomically very similar to a human. While generally amphibians are more susceptible to heat than we are, there are some that can do pretty well in hot situations (for a limited amount of time). So a lot would depend on a genetic predisposition. Early smelting practices suggest that ores were probably smelted in shallow pits. Archaeologist are still debating about this, but some think the draught to raise the temperature may have been achieved through the wind. If that was the case, you wouldn't really need to stay close to the furnace for long, which makes it much more likely for an amphibian sapient specie to be able to smelt. There's a couple more things that would help. The first is, as already pointed out by others, clothing. That's what we use to reduce our exposure to heat, and it's likely what they would use too. The second is proximity to water. It's very likely for a sapient amphibian specie to build their facilities and villages in very close proximity to water. Being able to take a few steps away to submerge yourself in water would greatly help. Not sure how practical this would be, but they could even try to do most of their work while partially submerged (think a shallow pool or something), which would reduce the dehydration rate. So in conclusione, while probably not their favorite task, smelting and metallurgy could easily be something they would do. [Answer] **Hands** (which imply opposable thumbs and bipedalism) and **large brains** are what you need for civilization and metallurgy. Whether your *amphibians* can evolve into sapience depends on how closely you adhere to the [terrestrial definition of amphibian](https://en.wikipedia.org/wiki/Amphibian). [Answer] There is no reason why being amphibious would impact there ability to smelt metals. If they are specifically lissamphibians, then that may effect their smelting, though not because of their skin. The actual problem with a lissamphibian smelting is the fact that they are generally simpler than other types of life. This means that they have less access to oxygen, which may limit their intelligence, and may also lead to them being smaller, which will make it harder to manipulate fires ]
[Question] [ Using the Tolkien depiction of Wargs (horse-sized and fairly intelligent large lupines that can be domesticated), where would they likely find an economic niche as livestock or work animals? I would imagine the polar regions, where sled dogs are already popular pack animals, would be a good place for domesticated Wargs, but are there any other environments where Wargs will be preferred over regular horses, mules, or oxen as work animals? [Answer] Plant eaters like horses and cows often have to constantly travel to make sure they dont deplete their resources, and occasionally run away when a predator tries to catch them. Their food doesnt run away, which is good. Predators on the other hand have a tough life. Their food makes them work hard to catch it, and that work costs energy. Other than what we see on television the actual catch rate isnt that high, there's a high likelyhood of the prey escaping. Combine that with the sneaking to find prey, having to cross a larger distance towards the prey and then needing to be strong enough to kill the prey and you can see why predators spend most of the day lazying around: it allows them to conserve energy for their next hunt. Wargs wouldnt be ploughing your fields any time soon. They are designed for short bursts of aggression with long pauzes and walking inbetween. So any job you give them needs to fill that niche. Obviously they can be ideal animals to hunt with. The combination of human ingenuity and the animal's natural potential would be powerful. Guard duty would fit reasonably well, but it depends on your goal. You usually do not want your guard animals to kill and eat intruders, especially if the intruder could be an employee called in to work late or a last-minute replacement to fill in for a sick guy. We teach our guard dogs to disable the intruder, not go for killing blows. They could function as a pack animal if they carry something light. This allows them to simultaneously guard the object and carry something, although likely not much. Some jobs that require a lot of sudden force could benefit from having a Warg perform it. Like a short pull on a pulley system. Perhaps on a fishing boat to haul in the nets for example. Maybe you can find a job for their claws and teeth. With some mouth gear a blacksmith should be able to find a few uses for their undoubtedly immense jaw strength. Those sharp nails and powerful paws could perhaps be used to do simple things like turn wood into chips ready for a good fire. [Answer] Your problem is feeding them. As riding animals unless they can be trained to eat dried, salted/processed/fish and grains etc Wargs are unsustainable in large numbers. In small numbers perhaps the problem is not so significant. A rich noble could probably afford to feed a 'stable' of say 12 Wargs. Anyone else?. A quick search says wolves need about about 4 pounds of meat per day to prosper. On average say 10-20 pounds every few days. If we assume Wargs need at least four times that amount to sustain their greater body mass *and* do useful 'work' for their owners (and they probably need much more) then the economic cost of using them as mounts outweighs their usefulness. Your talking about 16 pounds of raw meat a day x 12 equals about 180 pounds. That's at least a cow a week, probably more just for your nobles private stable! No kingdom or army on Earth could afford to sustain Wargs as mounts except for a small elite minority. An army mustering say 10 thousand riders on horseback can, with some oats and hay to supplement their diet sustain their mounts in the field for weeks and months at a time under relatively normal conditions. An army mounted on 10,000 Wargs would need what? a thousand cows a week! It wouldn't be an army it would be a cattle drive! And any country trying to sustain large numbers of Wargs would end up starving its own population. [Answer] If their water need is lower than that for horses, mules or oxen they might be a valid alternative in all the arid and semi arid climates, where supplying water can be difficult. Even without that they could be viable in any farming location, since they would take care of rodents and other critters feeding on harvests: they would be, at least partially, fed for free and doing so would indirectly increase their master's supplies. [Answer] Forget about rural work. These things have a role in security. You don't need to pay a guy with a flashlight and a stick o guard your museum, factory or mall if a horse-sized wolf will do a much better job for spg food + some bonus human flesh when they catch a trespasser. Wargs would also be great at dispersing riots. But where they really would excel is sniffing drugs in airports. You'd no longer need to do cavity searches, drug mules would evacuate the drugs off out of pure fear upon receiving a dog greeting from a warg. [Answer] I absolutely love the "sleg warg" idea, though that's more something for a fantasy/medieval setting. How about **pest/livestock control in forests**? Usually (at least in Germany) huntsmen sit on their high seat somewhere in the forest and wait for the occasional hog or doe to wander by - but a warg could flush them out or even bring them down on its own. This is done in order to reduce damages done to trees/ecosystems by the livestock while their original predators (wolves, sometimes lynx) are not present. Or they could be used as really big sheperd dogs. No sane wolf would go near a herd guarded by it's big cousin. ]
[Question] [ **Backstory** In around modern time in the United States there was a super secret science project, unknown to the general public. They invented an experimental [portal](https://static.wikia.nocookie.net/quake/images/b/bb/Teleportoutof.jpg/revision/latest/scale-to-width-down/310?cb=20110629171827) system, allowing to teleport people and goods between one super secret underground military base to another. First they tested the system with two portals, and it worked well. Then they added a third portal to the system, and then they were able to move people and goods between those three different locations, by selecting the destination portal from a computer. It all worked flawlessly, even teleporting between different states. However when they tried to added a fourth portal, to extend their portal system, a certain accident happened. Apparently they were able to power on the fourth portal and connect it to their existing portal system successfully, or so they thought. An employee stepped onto one of their already existing portals, in order to be teleported to the newly installed portal. The technicians set the destination portal on the computer, and then pulled the level. The man disappeared, and did not appear on the other destination portal. Furthermore, ever since the fourth portal was activated, any people or goods that were sent from any already existing portal to any other portal were sent, but they never reappeared on the other side. Even if both the sending portal and the destination portal were among the former three portals which previously worked. At the same time strange vases and pots began getting received on their portals, which they clearly hadn't sent. Little did they know, when they activated the fourth portal and connected it to their already existing portal system, their portal system got connected with an already existing portal system in a parallel universe. In that parallel universe, ancient East Asian civilizations had discovered magic/psychic powers, and after integrating such powers with technology they created many science fiction type inventions, one of which was a planet spanning [portal](https://static.wikia.nocookie.net/jakanddaxter/images/b/b0/Blue_Sage%27s_hut_interior.png/revision/latest/scale-to-width-down/1000?cb=20170829235639) system with thousands of gates on the alternate Earth. Since the Area 52 portal system got connected with the parallel Earth's portal system, anything that they would send would be received in some portal on the parallel Earth, instead of going to the intended destination. Any people or cargo that they transported would eventually be arrested by the parallel Earth's authorities. Furthermore, occasionally something would come into one of the Area 52 portals. **Question** In order for this plot to work, I have to explain why adding a fourth portal caused their already existing portal system (which worked fine with three portals) to connect with a portal system from that parallel universe. Why the number 4? What would be the quirks and features of that portal system for it to get connected like that? [Answer] ## Each Portal Has a Unique Frequency: The portals on Our Earth are operating differently than the portals in the parallel universe. It's a little like the portal system in Stargate, where the Earth portal has a human-made controller that operates slightly different from the rest. Since your people are able to "Dial up" portal locations, there must be something unique about each portal - a coordinate system of some kind. The fact it was the fourth portal, and not the first/second/third is a coincidence. Something about the fourth portal had a coordinate system that was close enough to the ones in the parallel universe so they intermeshed. But while the coordinates used by the system in the parallel universe have additional numerics/symbols/mystic components that give them specificity to their own portals, OUR system operates with different coding, and is only partially compatible. So once the fourth portal engaged the parallel universe one, our incompatible system intermeshed with theirs - badly. It started to cause malfunctions in the parallel universe, resulting in those random pots and things showing up here. The sheer volume of destinations in the parallel universe might cripple our portal system. The real question is, what would happen if you disable the fourth portal? Would you be able to "disengage" from the parallel universe and start over, or Is there a higher-dimensional network which is now intertwined? In the first case, you could disconnect and solve the problem short-term, but run the risk of reconnecting to this or other parallel universes in the future (unless you can somehow figure out why the parallel universe portals weren't having this problem before, and copy it to create a separate network). In the second case, the only "fix" would be to either shut down the whole thing or try to integrate better with the parallel portals. You might be able to stabilize and separate the portals by figuring out and copying their coordinate system. Then, our portals wouldn't send to theirs, and theirs wouldn't send to ours. It IS likely, however, that scientists/Enchanters on both sides would be working on figuring out what was going on. We could always use the "bad" coordinate system to tap into theirs, and eventually THEY would probably figure out what was going on and tap into ours. At that point, the real fun of storytelling starts. [Answer] ## The answer *will be* technobabble ... * There is nothing special about four portals. There is something special about version 0.2.3 of the control software, which became necessary to replace a simple boolean switch (one of two other portals) with a list of destinations. Version 0.2.3 of the software happens to use a newer version of a java library, which fixes a bug in the old version, which affected the tuning of the portal. Basically the tuning compensated for the bug, now the bug is gone and the portal is out of tune. *Of course* the researchers tried a rollback to the previous portal configuration and software version 0.1.9. But due to a misconfiguration, the rollback did not undo the library update, which was just a maintenance release with the same [major and minor version number](https://en.wikipedia.org/wiki/Software_versioning#Sequence-based_identifiers). * There is nothing special about four portals. There is something special about the fourth portal, which differed from the previous three. Perhaps all four were handmade prototypes, or four was the first pre-production run, or something like that. The fourth portal produced some sort of *static* which interfered with portal calibration across the multiverse. This kind of problem is nothing new for the portal operators on the other world. Instead of discarding an expensive portal, they are able to re-sync their network and to compensate. Unfortunately they didn't know about our experimental network. They have *more powerful* portals, and also *more* of them, so their calibration process integrated all four of ours into their network. Anything we send, their (more powerful) receiver will snatch. A few of the things they send, our (less powerful) receivers will snatch. That happens only with their lesser, less well maintained portals, the sort used for low-value cargo. [Answer] **Punching through** If you make a portal, you basically punch through some part of reality. A portal is open at two sides, so you're required to punch through twice. If you open another portal it'll need an exit. The portal will automatically probe for weak points where it can establish the other portal. Nothing is weaker than an already punched hole, so a connection is easily made with preexisting holes. That's why they made two at the same time at first so you know where to expect the holes. If a parallel universe punches a hole, it has a good chance to find the existing portals of normal Earth. If it must be random, the energy used 5o punch holes might inadvertently weakened parts of the parallel universe, punching through on the fourth hole. This can conceivably be moticed by the parallel universe, so they might have been ready. If you have several holes, you can go through and end up at any of them. If you calculate how to end up at hole x from hole y, your calculations will only be correct if you assume the right amount of holes. That's why they sometimes end up elsewhere from where they thought they would be. [Answer] They unknowingly stepped into a man in the middle type of attack to their system. When they set the first two portals they were intercepted by the other civilization. With the addition of the third portal they were triangulated in the multiverse foam and precisely located. With the forth portal the stream between the portals was diverted to the attacker's destination. Each intercepted item is now being scrutinized to better assess the capabilities of our side and prepare countermeasures in case of an attempt of foul play. [Answer] **Connected to the mothership.** There is a big computer in the parallel universe that controls the endpoints of all the portals. Each portal has an identifier number, and when a new portal is created it is by default connected to Portal 0. Then the computer can be used to redirect the portal. Now portals by default don't care about which universe they're in. When the fourth portal was created it was located by the central computer, which then located the other three, and defaulted them to end at Portal 0. Portal 0 is of course in the parallel universe. [Answer] # The fourth portal happens to be in precisely the same place as one of the portals in the parallel universe. However these portals work, the connection between them exists on a different plane. Unbeknownst to anyone in either universe, that plane is shared by both universes. The portal projects in both universes have been punching holes into a shared dimension, and so it was only a matter of time before the two collided. If only one universe was doing portal stuff, they could build as many portals as they want with no problem. By pure coincidence, our fourth portal was built in precisely the same position as one of the portals in the other universe, and so now the portal systems are linked. Perhaps it's even possible that the two networks could be disconnected if either of the two overlapping portals were destroyed. ]
[Question] [ The gods created the earth and the humans that live across it. Mankind developed their civilizations and cultures, worshipping various gods related to different aspects. Humanity worships the same gods, but in various ways and are attributed different personalities and images. A god of war for the Aztecs can have the form of a humanoid bull, be extremely violent and demand human sacrifice. In another culture, the same war god can be a woman who values strategy and tactics in battle and emphasize honor and protection of the weak. Every god has different representations and images around the world, but this is unknown to the majority of the population. Religious leaders of these nations eventually discover this and realize that the gods can be shaped and crafted to fit a certain profile. Once this is realized, they can lead their congregation in specific ways to mold the deity to their own purposes. A god can be completely changed over the course of many generations, but stays within its portfolio. This presents a contradiction. The gods are all powerful and created humanity in their image, but they have no control over how they are represented in society, as well as their personalities. This cedes a great deal of power and authority to worthless and insignificant mortals, specifically to priests. How can this be the case? [Answer] **It is only a representation** Gods are simply on a whole other level. They can't be fully comprehended by mere mortals. The way we worship them just gives access to a small representation of their power. Although we see a different entity and think we've manipulated the god, we just see a different part of the same vast unendingly complex entity. They already are the representation we worship them as, but they are equally so the others we don't worship them as right now. Do we really have control, or are we just fooling ourselves? Do we just unlock a portion of power with our worship? I would go with the fool scenario. We can't control, understand or manipulate a deity. Maybe we're more idle playthings and we don't know. [Answer] **This is how gods work in the real world!** Consider the New Testament god vs the Old Testament god. Could they be more different? Consider Christian churches - all follow Christ, but the political views backed by some churches are diametrically opposed to the the teachings of Christ in the Bible; Christ must be modified to fit, and is. It is ok. That is how it has to work. Gods are creations of humans and being such, can be influenced by operators such as you describe. I do not mean any of this in a pejorative way: gods and religions serve important cultural roles and need to be flexible or they will be obsolete. In your world, even the the gods have objective existence apart from their devotees their nature will be flexible according to those devotees. [American Gods](https://en.wikipedia.org/wiki/American_Gods) by Neil Gaiman does this up so well - gods need devotees or they cease to exist. The Odin of America is not at all the same as the Odin of the Old World. [Answer] ## The gods work on a slower time frame and don't really understand humans that well. Why would they understand human? They have very different need, a completely different upbringing, and a completely different social organization. Terry Pratchett plays with this a lot. Gods are not naturally that clever, and they are even worse long term planners. Why would they be? They don't need much problem solving. Once they are powerful enough to be intelligent, want something poof there it is. Maybe they tried steering their believers but kept failing miserably. The adventures of the god Odin: > > Ok lets try dropping this commandment to make them start actively > converting outsiders. > > > Wait no, now they are killing them instead of converting them. > > > Hmm, here is a commandment about being peaceful. > > > Shit, now they aren't fighting back against other tribes. > > > Ah here is one about pride, there, now they are defending themselves. > > > Wait now they are starting to kill each other over who is worshipping > me properly. > > > Uh uh, [Thou shall not kill fellow Odinites] that should work. > > > @#E\*, now they are killing each other *even* more, accusing each other > other of not be true Odinites. > > > [Smite smite, commandment] You know what screw it, I give up. You > people do what you want. > > > And now I'm Santa Claus, what the $%#@& is going on. > > > Why would this lead to them letting their priests call the shots? Because their priests DO understand humans and they understand changes in society. The god of a thousand years ago will not do as well in today's society. So they are giving up some control in return for better results. They created a competitive market and you need marketing that understands the buyer and just as importantly can adapt with the times. [Answer] **There are self-imposed rules and balances among the gods** While powerful toward the mortals, obviously a god's power is on the same level of his colleagues. In the past, if a god saw his worshippers screwed by another god, he took the thing as an ingerence on his properties and a personal offence. This brought a lot of infighting and animosity among the gods which eventually resulted in an all-out war in the heavens. When the gods realized that this situation was unbearable, they decided to join a gentleman's agreement: every god has a limited set of actions that he can perform on the land of mortals. Say, for instance, in a month every god is allowed 3 direct manifestations, 5 enhancement of mortal warriors, 2 lighting bolt on other worshippers and so on... Contavening to these rules would cause all other gods to join the forces against the transgressor, so they are usually respected. Because of this, the gods must try to optimize the impact of their direct actions on their worshippers, in order to have them thrive (usually at the expenses of the followers of other gods). Among the others, this implies: * it's a waste to correct some trivial mistakes in the cult: if the worshipper think that the god of war has the shape of a bull or a sabre-toothed tiger, it is ok to let them think so. The god of war has no point to waste an action to manifest himself only to explain that he looks like a bunny in reality * the societies, now less influenced by their gods, are more free to follow different paths of civilizations. This means that what they ask to a god of war or of knowledge can differ a lot among different populations. For a god is less costly (in term of actions) to give them directly what they ask, rather than trying to influence their societies as a whole * for the same reason, the gods, needing to keep their followers, are more compelled to give what people ask them, since they have less options to recover in case of unsatisfied worshippers. [Answer] A great deal of power and control? How could anyone gain a great deal of power and control by dictating to a small group of worthless and insignificant mortals? Does the king on his throne care what the urchins mutter about him? Does it matter to him that one says that he's a tyrant, and another that he's all-good and would do something about their plight if only he knew? The difference being that the mutters might actually spell trouble for the king, whereas for the gods, the worthless and insignificant mortals can not possibly cause any trouble at all. Let some of them lead their flocks into error. Perhaps the consequences might be slightly amusing. And if, for any reason from slight annoyance to boredom, you dislike the result, you can send plague, famine, destruction and disaster on the worshippers, and give signs that you are angry with their worship. They'll straighten up REAL quick. Or you could just wipe them out. [Answer] Gods are otherdimensional entities of such flipping power that they can't interact directly with the material world, because the material world would probably not survive the experience intact, so instead of interacting with their full, pure, power, they interact through fragments of themselves, basically avatars. These avatars have a mere miniscule amount of their larger self's true power, but it is still enough that the avatars have godlike levels of power in comparison to mere mortals. A god may have a number of avatars running around, but the more avatars, the more limited each is. Thing is, these deities don't operate on quite the same level as humans and have trouble relating to humans much like a human would have trouble relating to a bee or an ant. In order to be able to interact, their avatars are amorphous, changeable entities, created to reflect the views and values of the humans who worship them, as restrained and modified by the basic nature of the deity the avatars are part of. People then see the avatar, which the initial worshippers have molded in their own image of what their god(dess) is, and conform their own worship to that of the avatar's apparent personality, which is then reinforced or changed by the greater number of worshippers, and so on into a feedback loop. This happens enough and the avatar becomes associated so specifically with one particular part of the deity's overall aspect that it creates an opening that another avatar (or the same deity, or perhaps another) can then fill. To use your example, the deity of war has an avatar that eventually becomes associated with violence and bloodshed and the glory of combat, leaving an opening for a deity that represent strategy, just causes, and smart victories. So that war deity sends another avatar that fills that role. And eventually you have the stereotypes of Ares and Athena. [Answer] I don't see a problem with the situation you present, I think you just need to make a couple tweaks to how you interpret what's going on. > > Every god has different representations and images around the world, but this is unknown to the majority of the population > > > So far you haven't actually mentioned that the god's real shape actually changes. Then perhaps it doesn't. What I mean is, what changes is only the image of the god that the mortals have. The true form of the god is something more general and abstract, a concept, a mind. They still have their intents and personalities but aren't really tied or changed by the way the mortals portray them, and may have their own true or favored forms. Gods can be worshipped in different forms because they all ring true to the god's core ideal. The bull and the female strategist you gave as examples can both represent the God of War, as they both carry the idea that "You and I have a disagreement and we are solving it in the field of battle". That is how that God thinks things should be settled, and as long as those forms ring true to this, they will hold some power. ## So, why is it relevant how the mortals portray the gods? Well, the gods are real in your world, so I assume they have some effect in the world. The blood sacrifices the Bull War God receive will confer the warriors some boon in battle. In turn, the generals being inspired to find better solutions and strategies will have to attain to that manifestation of god's honor code. No backstabbing, no backing down from someone who affronts your honor, or you lose your god's favor. There is a cost and there is a reward. Different forms will have different rules for this, that all fall in line to how they are represented. They all work cause they are all true facets of that particular god, the god doesn't care which one is being worshipped and believed in at the time. Why not worship all at the same time then? Well, perhaps some mortals could hold and accept all those ideals in mind, but most would not hold on to and believe each facet as strongly. The same way they couldn't comprehend the true form of the god. That's why simpler, defined manifestations that take on ordinary, worldly things are generally more effective. With this knowledge, priests (at the orders of a ruler for instance) could sway the impressions of the worshipers to get the aspect of the god that better suits the kingdom's needs. Do you want to subjugate neighboring tribes? Make the Bull form of the War god gain believers. As you consolidate your power and control more land and face stronger adversaries where brute force doesn't cut it, transition to the General aspect. This works more smoothly if it is planned beforehand. [Answer] Well, we are created in their image, yes? Highly simplistic, but a lot more philosophical if you think that way. We are but the faintest image of the very-powerful deities that spawned us. As such, we as a race have the tiniest shards of that power. On its own though, this does nothing. But the priests, who know a bit more of the true nature of the deities, and the congregations that follow them, pool the reflected shards of power together. And once enough shards of reflected power join together in a common task, the can perform the barest act of creation. It takes so long because there's a million faint points of light as opposed to a single sun. That creation is the image of their deity. The gods created mortals, and in reflection the mortals maintain the gods. The mortals changing the image of their deity in turn changes the deity that they see. After all, that bull-headed deity did not create literal bull-headed humans -- that image is the reflection on what a god of war is to those people. So their image of themselves and war reflect this bull-headed deity. As they change as a society and their views on war change, so too does the people reflected image of a deity of war. The true mystery is in fact the true nature of a deity. My suspicion is that the image that we see is a form that we are comfortable with, we reflect back something that we understand relating to the domain. My suspicion would be that they are a higher-dimensional being that we could not hope to comprehend and stay the same once we do. The images that we humans give them are almost like us putting on a costume and acting a part, but that is our human mind trying to attribute human justifications to their actions (or non-actions as the case may be). Of course, this is not something that we will ever fully understand, because if we were to ever truly understand, that would be ... Interesting. Likely in the cursed sense of the word. In short, to us mortals it's a philosophical conundrum. [Answer] ## Gods need to increase and keep their core constituency Gods get power from their worshipers. The more worshiper they have, the more power they have. Therefore, they accept to be seen diferently as long as it brings more followers. Take the example of a politician, that need to maximize his votes, the town A which is for a law, and the town B which is against. He can go to town A, and make a speech telling how this law is wonderfull and how he will pass the law if he is elected. Then, he goes to town B, and make a speech about how this law is evil, and how he will fight it if he is elected. As long as there is no contact between the two towns, he will be elected in both, despite being contradictory. He don't mind beeing view diferently in two towns, as long as he is elected in both. Your Gods are like this crooked politician, and the towns are like your civilizations. A god of war for the Aztecs can have the form of a humanoid bull, be extremely violent and demand human sacrifice. Because this fits the culture and core values of the Aztecs, and therefore make this god popular. In another culture, the same war god can be a woman who values strategy and tactics in battle and emphasize honor and protection of the weak. Because this fits the culture and core values of this other culture, and therefore make this god popular. Society changes, and Gods just change according to this in order to stay popular. They trade control of their representation in exchange of power. [Answer] ## The gods where bored The Gods have created humanity to use their collective psychic consciousness to become stronger for their own reasons. The only drawback is that this must happen out of the free will of human society, this means they cannot interfere with human society. The power they get from humanity is more than worth the trouble it brings with it. Via this way of gaining power the god changes in a myriad of ways other than gaining more power. Different societies believe in the same gods in different ways and as a side-effect the gods split into multiple personalities. All these personalities are all part of the whole metaphysical god. When the priests find out about this and use their processions to change the god to their liking, the power of that god also changes. Although a nuisance, the gods are far to busy with their own powerplay and competition for dominance to be bothered with those worthless and insignificant mortals and their priests. The gods might even practice the rule of *"fair game"* as a way to get through the eons without getting bored. [Answer] Automation. Slick desing. 7 continent processor. Multi-tasking. Gods created earth as we create machines to make our lifes easier. You need to put heavy weight on top of the stack? Use crane. Strenght. You need to find fastest route? GPS. Strategy. The human think they can shape gos like THEY want but in reality they just make electric plane. Work just like regular plane just faster. And need electricity. Provided by the believers. The gods have planted the seed and now they're picking the fruits. Oranges! Apples! Bananas! From the same tree! Yeah, sometimes you get that useless twirling spaghetti fork instead of a cool thing but it's a price gods are ok to pay. After all, it's not their power that is wasted. ]
[Question] [ **Premise** I’m trying to design a planet with atmospheric conditions nearly identical to Earth, but with roughly the same size and mass of Titan. Titan lacks the conditions to maintain an atmosphere on its own like Earth, it depends on the magnetosphere of Saturn. The conditions on Titan aren’t really compatible with human life or the story I’m writing, because it’s tidally locked and far too cold. So, using the magnetosphere of a gas giant isn’t an ideal situation for the planet I wish to create. Instead, I want to explore the idea of an artificially created atmosphere. Humans regularly produce artificial atmospheres in sealed chambers. I think a sufficiently advanced space faring civilization could conceivably put a bubble around a planet and pump it full of gasses. **Actual Question** Could a gigantic gas-filled bubble substitute the gravity and magnetosphere required to maintain an atmosphere? [Answer] ### A pressurised bubble held by a strong global shell should be possible In this model there's a semi-flexible shell (of a strong, light, airtight material - eg graphene), that's been inflated with oxygen. Its mounted using 2 attachment points at the poles, 100m-1km tall, back of the envelope calculations show graphene is easily strong enough to hold a 0.5atm atmosphere pushing up, or titans 1-2m/s/s gravity pulling it down. At 130gpa (~200 times stronger than steel) it should be able to stand up to most low-medium speed impacts, and the odd high speed meteorite would be decelerated by the shell considerably, but still require a patch. [![enter image description here](https://i.stack.imgur.com/VSeL6.png)](https://i.stack.imgur.com/VSeL6.png) The shell, cylinders, and atmosphere are synchronised to the planets rotation, so no strong winds or rotating parts. The cylinders could be hollow in order to implement an airlock allowing ships to land "air tightly". (Kevlar, Carbon Fibre, Carbon nanotubes, and a few other materials should also be strong enough to implement this structure, but I'm not sure these can be made sufficiently airtight easily). [Answer] ## It's certainly possible **Domes** It depends on what exactly you are tying to achieve. Doming over the planet, either with small bubble domes or a global bubble is certainly possible. The small domes are best if the settlement is gradual, the global dome needs to be supported. A global dome might be held up by air pressure alone, given you use some aerogel like substance, a robotic repair ecosystem and an orbita point defense network. Landing spacecraft could either go through airlocks between dynamically suspended Atlas-towers or just punch through the dome, if it has advanced self repair capabilities. Dynamic support structures would definetly come in handy for keeping the dome up. Check out orbital rings and atlas towers. Nanotechnology-heavy civilisations might favor the aerogel dome, and ones with advanced biotec could plant a global forest of vacuum hardened Dyson trees, producing habitable bubbles, which connect to each other on the ground. **Other Ideas** You don't nessesarily need a dome. If the moon was give an earthlike atmosphere, it would retain it for millions of years. What we call rock is mostly made of oxygen, Earth is an "oxygen-metal-planet". If your civilisation has a abundant energy, it could just thermally break down rock to counterbalance atmospheric losses. One could just use the facilities one used to build the atmosphere in the first place. Of cause, this means that a pure, 0.25 atm oxygen atmosphere would be best for humans here. This isn't dramatic, there will be a slight increase in firehazards and one would need be vigilant about supplying nitrogen to plants (probably via irrigation in richly greened areas, in other areas plants adapted for nitrogen conservation might be a good idea). Another option would be to ditch the surface altogether and either dig out or settle natural caverns. Especially on icy moons this mightv be the preferred option, as a few meters or kilometers of ice or rock beat an atmosphere for protection any time. Geothermal energy or deuterium fusion could very well be better energy sources. A rather radical option would be to ditch the idea of an atmosphere altogether and adapt the ecosphere for life in vacuum. Using genetic engineering and cybernetic augmentation might result in a fascinating biosphere, where solar forests grow capacitor fruits, which symbiotic robots and cyborgs can drink from. Cybernetic animals might dig up resources and take care of the trees. [Answer] I think it will be simplier to build a lot of really big (about 1 km heigh) linked together geodomes (see picture) on surface of your planet, and fill them with breathable atmosphere and place plants, bees and animals in them to make ecosystem self sustaining and suitable for humans to live in it. I think its quite simple approach for space faring civilisation, since it can use materials found on surface of planet to achieve it. Artificial lights in domes can emulate Earth day and nights and even seasons, alongside allowing plants to perform photosyntheses. Unfortunately, this approach only allows us to emulate atmosphere of Earth, not gravity. But, after few generations all lifeforms will adapt to lower gravity. [![geodomes](https://i.stack.imgur.com/NTrHR.png)](https://i.stack.imgur.com/NTrHR.png) [Answer] Variations: 1. Artificial magnetic field. Some powerline-like setup around the equator, some power stations (solar is probably OK), some maintenance effort and you are set. The atmosphere will have to be ticker than Earth's, just like Titan one is, in order to get acceptable pressure. 2. Thin shell (supported by its own tensile strength). Discussed in other answers. 3. Thick shell. Like the thin one, but supported (mostly) by the weight of a material and structures piled over, instead of its own tensile strength. Advantages: a great deal of protection against small meteorites, cheaper materials, lower technology, lower heat loses. Disadvantages: dark inside. May be possible to use "light wells" like in medieval buildings with the added possibility of using heliostat mirrors to feed light into them. 4. Thick transparent shell. As above, but glass or glacier-like material above. Like above, but allows for Earth-like agriculture. Glacier-like material may be self-healing to some extent. 5. Domes - discussed in other answers. Works like either the thin or the thick shell, but over small area. 6. A patchwork of 2, 3, 4 and 5. Diverse (allowing for different activities) and fault-tolerant. They can be even combined with 1 for much less dense, but still somewhat survivable atmosphere above. [Answer] I don't think it is possible. I see two issues with your idea: 1. How to sustain a planet wide structure without having it collapse under its own weight. You are talking about a shell which has to wrap the entire planet to hold its atmosphere. It won't weight peanuts, and you want to make it robust enough to withstand impacts with space debris, which will slowly make it look like a fishnet, piercing holes through which the gas will leak out. 2. Those working with vacuum chambers know that, after a certain vacuum, materials start to become leaky to gases. So, in your cases having an atmosphere on one side and the deep vacuum of space on the other will put you in the same situation. [Answer] The OP, Mahaus, is wrong about Titan. Titan is unsuited for being habitable for humans because it has an excape velocity which is too low to retain gases such as oxygen, not because of its lack of a magnetosphere t o prevent the solar wind fron knocking molecules out of its atmosphere. The first necessity to maintain an atmosphere on a world is sufficient escape velocity. Having a strong magnetosphere to defect particles of the salor wind away from the world and its atmosphere is a secondary consideration. Note that the planet Venus has a highly dense atmosphere, despite having a very weak magnetossphere compared to Earth. > > In 1967, Venera 4 found Venus' magnetic field to be much weaker than that of Earth. This magnetic field is induced by an interaction between the ionosphere and the solar wind,[106][107] rather than by an internal dynamo as in the Earth's core. Venus' small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. > > > The weak magnetosphere around Venus means that the solar wind is interacting directly with its outer atmosphere. Here, ions of hydrogen and oxygen are being created by the dissociation of neutral molecules from ultraviolet radiation. The solar wind then supplies energy that gives some of these ions sufficient velocity to escape Venus' gravity field. This erosion process results in a steady loss of low-mass hydrogen, helium, and oxygen ions, whereas higher-mass molecules, such as carbon dioxide, are more likely to be retained. Atmospheric erosion by the solar wind probably led to the loss of most of Venus' water during the first billion years after it formed.[112] The erosion has increased the ratio of higher-mass deuterium to lower-mass hydrogen in the atmosphere 100 times compared to the rest of the solar system.[113] > > > [https://en.wikipedia.org/wiki/Venus#Magnetic\_field\_and\_core[1]](https://en.wikipedia.org/wiki/Venus#Magnetic_field_and_core%5B1%5D) Vwnus has lost a lot of atoms of lighter elements from its atmosphere due to a week magnetosphere. But Venus still retains a very dense and massive atmosphere: > > Venus has an extremely dense atmosphere composed of 96.5% carbon dioxide, 3.5% nitrogen, and traces of other gases including sulfur dioxide.[64] The mass of its atmosphere is 93 times that of Earth's, whereas the pressure at its surface is about 92 times that at Earth's—a pressure equivalent to that at a depth of nearly 1 km (5⁄8 mi) under Earth's oceans. The density at the surface is 65 kg/m3, 6.5% that of water or 50 times as dense as Earth's atmosphere at 293 K (20 °C; 68 °F) at sea level. The CO2-rich atmosphere generates the strongest greenhouse effect in the Solar System, creating surface temperatures of at least 735 K (462 °C; 864 °F).[17][65] This makes Venus' surface hotter than Mercury's, which has a minimum surface temperature of 53 K (−220 °C; −364 °F) and maximum surface temperature of 700 K (427 °C; 801 °F),[66][67] even though Venus is nearly twice Mercury's distance from the Sun and thus receives only 25% of Mercury's solar irradiance. This temperature is higher than that used for sterilization. > > > [https://en.wikipedia.org/wiki/Venus#Atmosphere\_and\_climate[2]](https://en.wikipedia.org/wiki/Venus#Atmosphere_and_climate%5B2%5D) Venus is obviously not going to lose its atmosphere to space anytime soon. It has kept an atmosphere many times as dense as Earth's for billions of years. The less massive an astronomical object is, the lower its escept e velocity is likely to be. And the lower the escape velocity, the faster the object looses whatever atmosphere it has. And the lower the escape velocity, and the stronger the solar wind hitting the atmosphere is, the faster the solar wind will accelerate ions to the lower escape velocity. So on a low mass world with a low escape velocity, the weaker the magnetosphere is the faster the solar wind will accelerate the loss of atmsophere. A weak magnetosphere is most effective in removing atmosphere from a world that has so low an escape velocity that it is losing atmosphere anyway. A weak magnetosphere makes a bad situation worse. And as a general rule, the more massive a world is, the stronger its magnetosphere is likely to be. Someone interested in writing about habitable planets, moons and other worlds should read *Habitable planets for Man* Stephen H. Dole, 1964, 2007. [https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf[3]](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B3%5D) It includes scientific discussions of many habitability related factors including the possible mass range of a habitable planet. Note that your example of a low mass world, Titan, has a mass of 0.0225 Earth, while Dole's calculated minimum mass for a planet to retain a dense oxygen rich atmosphere is 0.195 Earth, 8.6666 times as massive as Titan. So that explains why Titan is basically airless. Actually, of course, Titan has a significant atmosphere, with a surface pressure greater than the surface pressure of Earth's atmosphere. Like Earth's atmosphere, Titan's atmosphere is mostly nitrogen, but unlike Earth's atmosphere, Titan's contains no free oxygen. One major reason why Titan has such a dense atmosphere billions of years after forming is that Titan orbits Saturn, which orbits the sun at a distance of 9.5 Astronomical units, which is 13.194 times the distance of Venus from the Sun and 9.5 times the distance of Earth from the Sun. So at Titan's distance from the Sun, it receives only 0.0110 times as much solar radiation as Earth, and only 0.005744 times as much solar radiation as Venus. That means that the average temperatures in the upper layers of Titan's atmosphere are much lower than the average temperatures in the upper layers of Earth's atmosphere. So atoms move much slower in the upper layers of Titan's atmosphere, the layers that lose atmosphere, than they are in the upper layers of Earth's atmopshere. This enables the lower escape velocity of Titan to retain atmsphere much longer than it would if Titan had Earth's temperature. I also note that if Titan receives only 0.0110 as much radiation from the Sun as Earth and only 0.005744 as much a Venus, that includes the solar wind. The solar wind would obvious take a much longer time to knock away Titan's atmosphere at the distance of Saturn than it would take at the distances of Earth or Venus. Anyone interested in the possibility of habitable exomoons orbiting giant exoplanets in other star systems should read: Heller, Rene, and Barnes, Roy "Exomoon habitability Constrained by Illumination and Tidal Heating" 2013. [https://arxiv.org/ftp/arxiv/papers/1209/1209.5323.pdf[4]](https://arxiv.org/ftp/arxiv/papers/1209/1209.5323.pdf%5B4%5D) and: Heller, René (September 2013). "Magnetic shielding of exomoons beyond the circumplanetary habitable edge". The Astrophysical Journal Letters. 776 (2): L33. [https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33/pdf[5]](https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33/pdf%5B5%5D) Acccording to the later paper, exomoons orbitating larger giant planets at distances between 5 and 20 planetary radii will be within the planetary magnetosphere. Saturn has an equatorial radius of 62.268 kilometers or 36,184 miles, so moons orbiting Saturn at distances of 311,340 to 1,245,360 kilometers should be within the planetary magnetosphere. Tital orbits Saturn at a distance of 1,221,630 kilometers and so may have been protected from losing atmosphere to the solar wind by Saturn's magnetosphere. In any case, Titan does have a dense atmosphere, despite it's low mass and escape velocity,perhaps being able to produce or otherwise acquire atmosphere faster than it is losing it. Of course if the story involves a low gravity world with a dense atmosphere which is breathable to humans at the surface and has a temperature suitable for humans at the surface, there is a problem. Titan's doesn't satisfy either requirement, and probably would not be able to retain its atmosphere if it was at Earth's distance from the Sun. What is needed is a world with the surface gravity and escape velocity of Titan, and with temperatures at the surface similar to those of Earth, but almost as cold as those of Titan at the outer layers of it's atomsphere where atoms escape into space, and with a breathable atmosphere at the surface. One way to do so might be the make the world an exomoon orbiting a giant exoplanet in another star system. The giant exoplanet and its exomoon orbit their star at such a distance that the amount of radiation they receive from their star is much less than Earth gets from the Sun, but more than Titan gets from the Sun. Thus possibly the outer layers of the exomoon's atmosphere will be could enough that the exomoon will lose atmosphere faster than Earth, but slow enugh to retain it from billions of years. But then, if the exomoon is heated only by radiation from the star, it's surface should be for too cold for humans or similar life forms. Thus the surface of the exomoon should be heated to temperatures suitable for Earth life by internal heat, probably produced by tidal heating due to the tidal forces exerted on the exomoon by the giant exoplanet and by any other large exomoons it might have. And possibly the lower atmosphere of the exomoon contains enough greenhouse gases like carbond dixode and water vapor to retain a significant percentage of the tidal heating, so that the upper atmosphere is not much heated by escaping tidal heating - but not enough of those gases to make the lower atmosphere unbreathable for humans or similar beings. And also see my answer to this question: [https://worldbuilding.stackexchange.com/questions/189995/what-is-the-smallest-a-planet-can-be-whilst-retaining-a-venus-like-atmosphere/190021#190021[6]](https://worldbuilding.stackexchange.com/questions/189995/what-is-the-smallest-a-planet-can-be-whilst-retaining-a-venus-like-atmosphere/190021#190021%5B6%5D) I believe in the later article there is a discussion of the proper distance for a habitable exomoon orbiting a giant exoplanet. ]
[Question] [ It seems that one of the main hurdles of creating an interstellar propulsion system is the need to carry reaction mass to accelerate while conserving momentum. Pretty much every "fringe science" propulsion proposal tries eliminate this problem (e.g. [EmDrive](https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster), [MEGA drive](https://en.wikipedia.org/wiki/Woodward_effect), [Alcubierre drive](https://en.wikipedia.org/wiki/Alcubierre_drive), almost as if bypassing conservation of momentum is a primary need). But we know electromagnetic waves can be used as reaction mass to satisfy conservation of momentum (that is how light sail works), so we don't really need to carry reaction mass. The questions: 1. Excluding "passive systems", like a light sail accelerated from an Earth based laser, have photon propulsion ever been seriously considered for starship drives? 2. Considering the time it takes and the amount of fuel required, is there any way an ordinary nuclear fission reactor placed in the focus of a parabolic dish at the back of a starship power it to the nearest star using heat radiation as propellant? 3. If not this, is there any workable design? [Answer] **Excluding "passive systems", like a light sail accelerated from an Earth based laser, have photon propulsion ever been seriously considered for starship drives?** Yes. See [the Atomic Rockets page on photon rockets](http://www.projectrho.com/public_html/rocket/enginelist.php#id--Other--Photon). The classic photon rocket is an antimatter-powered drive propelled by gamma rays. Similar drives show up sporadically in science fiction. E.g., the personal rocket devices used by the aliens in Donald Moffitt's *The Jupiter Theft* are photon drives powered by total matter-energy conversion. **Considering the time it takes and the amount of fuel required, is there any way an ordinary nuclear fission reactor placed in the focus of a parabolic dish at the back of a starship power it to the nearest star using heat radiation as propellant?** Sure. Over a sufficiently long time, you don't need a whole lot of thrust to get up to very high speeds. **If not this, is there any workable design?** If you are using a fission reactor anyway, you might consider a [Fission fragment rocket](https://en.wikipedia.org/wiki/Fission-fragment_rocket), which gives you a better power-to-thrust ratio than a pure photon rocket does. [Answer] The trouble with all those fringe sciences is that eventually one of them sticks, and becomes real. If we end up building interstellar travel, its a safe bet that 2020 physics says the engine we used was impossible, just as 1850 physics said time dilation of fast moving objects was impossible. That said, I reckon there is one that's feasible within near future science: A Brussard ramjet. If you can capture the interstellar medium, and accelerate it away from you using a particle accelerator, that thrust is enough to make a difference. The [intersteller medium](https://en.wikipedia.org/wiki/Interstellar_medium) is 70% hydrogen gas, and about 10^6 molecules per cm^3. That's 10^-21kg per cm^3, or 10^-15 per m^3. A 10sqm sucker mounted on the front of a ship can collect a few micrograms every km of travel. Combine that infinite source of free particles with tech like [this single chip can accelerate a particle to 0.94c](https://phys.org/news/2020-01-particle-chip.html), and you've got a few N of free acceleration for every km of forward movement. Yeah it's no star wars battle with sharp dogfights, but that could get a generation ship to a nearby star system. [Answer] [The Atomic Rockets page on photon drives](http://www.projectrho.com/public_html/rocket/enginelist.php#id--Other--Photon) conveys that at perfect efficiency in converting reactor power to a collated gamma ray beam (not happening; there will be waste heat, dispersion...), it takes *three hundred megawatts* of power to produce *one newton* of thrust. Unless you'd like to have your building-sized spacecraft accelerate with less than a millionth of a gee, fission reactors are out the window, as are most modern conceptions of fusion reactors. The only really efficient way to convert mass to energy on the scale needed for this kind of drive is a matter-antimatter reaction; proposed photon drive rockets use big tanks of antimatter as their fuel. Since there is no currently feasible way to produce large amounts of antimatter, photon rockets have not been seriously considered by space agencies. [Answer] **Yes. Using electrodynamic propulsion.** [![satellite with electrodynamic propulsion](https://i.stack.imgur.com/E4RSS.png)](https://i.stack.imgur.com/E4RSS.png) <https://www.scientificamerican.com/article/kilometer-long-space-tether-tests-fuel-free-propulsion/> Electrodynamic propulsion relies on a long charged [electrodynamic tether](https://en.wikipedia.org/wiki/Electrodynamic_tether). The tether is charged by the spacecraft and by interacting with magnetic fields in space, it can generate propulsion. It still costs energy, but there is no reaction mass and nothing to be hurled behind the spacecraft - just the interaction of charged fields. There are spacecraft now which operate using this principle. <https://www.scientificamerican.com/article/kilometer-long-space-tether-tests-fuel-free-propulsion/> > > “In other words, it is the sailing ship of space,” says Enrico > Lorenzini, a professor of energy management engineering at the > University of Padova in Italy, who is not involved in the TEPCE > mission. But instead of wind, the electrodynamic tether technology > moves thanks to the physical laws that govern electric and magnetic > fields. A tether in Earth’s ionosphere—an upper atmospheric layer > filled with charged particles such as free electrons and positive > ions—can collect electrons at one end and emit them at the other, > generating an electric current through itself. The electrified > tether’s interactions with Earth’s magnetic field produce an impetus > known as the Lorentz force, which pushes on the tether in a > perpendicular direction. > > > There are plenty of magnetic fields in a solar system and especially in the neighborhood of a dynamo like Earth. But are there magnetic fields in deep space? There are, but their provenance remains somewhat mysterious. <http://www.scholarpedia.org/article/Galactic_magnetic_fields> [![magnetic fields](https://i.stack.imgur.com/KzpoD.png)](https://i.stack.imgur.com/KzpoD.png) > > The ISM contains equal numbers of positively and negatively charged > particles, so that large-scale electric currents (that could induce > large-scale magnetic fields) cannot be maintained. The most promising > mechanism for field amplification is the dynamo that transfers > mechanical energy into magnetic energy... With a suitable > configuration of the gas flow, a strong magnetic field with a > stationary or oscillating configuration can be generated from a weak > seed field. Seed fields could have been generated in the early > Universe, e.g. at cosmological phase transitions, or in shocks in > protogalactic halos (Biermann battery), or through fluctuations in the > protogalactic plasma. > > > To traverse interstellar space using electrodynamic propulsion, one would need to identify favorable force lines and align the ship with their path. This lends itself to a fiction because as professor Lorenzini noted in the above quote, it becomes analogous to a ship in the days of sail. And for pushing off against the energy of weak fields one needs a larger sail, or tether. I envision a huge skein of copper wires billowing around the spacecraft, glowing a slight green with its own charge and faint copper ion plasma. And you will need to be ready to take it down if a storm comes... [Answer] I don't know if photon propulsion has been considered, but it's likely not because of the low energy. Photons officially have *no mass*. If I can quote wikipedia: The total force exerted on an 800 by 800 meter solar sail, for example, is about 5 newtons (1.1 lbf) at Earth's distance from the Sun. Now interstellar travel doesn't require a lot of energy. Simply putting in more energy is enough, as there is (practically) nothing to slow the craft down. So some engines have been proposed that accelerate very, very slowly, but they can move for decades, if not possibly centuries on end. But light on Earth distance on an 800 by 800 large sheet isn't a small amount of energy. The reason to use light is that it is already abundant, or can be used in beam sailing as you say. With the propelling laser based outside the craft. Putting it on the craft has several very bad implications. You'll have to push against the reactor as well, and in general firing something pushes you backwards with the same amount of force. I don't know if the same applies to light, but you might just put as much force backwards as forwards if you apply it to a sail. Then you might better just aim it backwards and fire away for acceleration. An alternative is much more likely. Using the energy of the reactor, fire tiny particles as hard as possible backwards. If you push the particle backwards, you'll push the craft forwards with equal force. So with a particle accelerator inside you might expel the particles with as much force as a nuclear reactor can manage, making as efficiently use of the particles as possible. There are some further alternatives, like they are trying to use curves of spacetime to their advantage, generating a deeper field in front of the craft than at the back, pulling it forwards. But if you really want to have an EM drive, check out what NASA is doing at this time with it. Already in 2015 they were doing experiments to check if it could really work, as physics said [it couldn't.](https://www.sciencealert.com/leaked-nasa-paper-shows-the-impossible-em-drive-really-does-work) Still it does work a tiny, tiny amount. Seems negligible, but is according to them pretty impressive. More research is obviously needed to make very, very sure it isn't an error, but it might well be possible to use it later. [Answer] The title of the question looked promising, but the body then went somewhat off on a tangent. In the elaboration on the question, it is still assuming that 'reaction mass' is the only way to propel something. Yes, the laws of conservation of momentum require energy to be input into a system to create acceleration, but they do not require that reaction mass is necessary, nor that the energy source be inherent or contained in the object that you require to be moved. There are hundreds of examples of transportation/propuldion systems on earth that do not use 'reaction mass'. That is, they have exactly the same mass at the end of the journey as they do at the beginning, without refilling. They mostly use electricity and electrical motors (those that do not depend on gravity to pull them down to earth). A trolly car, for instance, can go a great distance without its mass being changed one iota. Okay, so it is constantly supplied with energy, but electricity is hardly a 'reaction mass', the electrons are returned to source. Tesla's hyperlopp system, where the propulsion system consists of electromagnets in the tube wall propelling the cars, is another example. No reaction mass need be carried at all by the train. Maglev systems are currently in operation using induction motors that require no energy be supplied to the trains. We even have [tractor beams](https://www.nasa.gov/topics/technology/features/tractor-beam.html) under develpoment as serious no-reaction-mass-required transportation systems. There are also many propulsion systems currently used in space travel that do not use reaction mass. They use the gravitational boost of planets, in a sling-shot maneuver, to boost speed. As a future-feasible practical example, using electromagnets (as the title suggests), think of a regular, commercial flight path between say Earth and Mars. Along the path, place super-huge satelite way stations powered by fusion ractors or such. They exert a powerful electromagnetic field (or other such tractor beam) along the route, such that they alternately attract and then repel the spaceship along the route. Newton, of course, woukd insist that their mass would have to be substabtially greater than the 'cars' they pull/push, and substantial development would be required in being able to focus/direct/concentrate the electromagnetic field, but this is an engineering problem more than it is a physics problem. Like Ash said in his (her?) answer, it is only a matter of time before the physics and enginnering textbook get thick enough to allow this scenario, first on an within-star, then an inerstellar system. But the bottom line is, the laws of the conservation of momentum do not **demand** reaction mass be used for propulsion, just some form of supplied energy. ]
[Question] [ Question- would a tesla coil function in space? What I think would happen- Tesla coils are basically a high DC voltage arcing through the air, searching for the easiest path to ground. A single coil will just send out sparks that dissipate(depends on the power level) a few inches away from the coil. If there are 2 that are linked, the electricity flows through one to the other. BUT, in both of these cases, there was one thing present in both of them- atmosphere, which is where I'm concerned. I've heard that tesla coils are used to test for a vacuum, and if nothing happens, then you have a vacuum. I don't think tesla coils would work in space, but I might be wrong, so somebody either correct or confirm this. BONUS- If you can, also try and figure out a way maybe they could work as spacecraft weaponry. [Answer] **No** Tesla coil arcs, like all expressions of electricity, need somewhere to go. The electric arcs they produce aren't aimed, they're attracted to a ground. Theoretically, if the opposing ship were at a significantly lower electrical potential than your own, that would attract the arc (as long as something else wasn't lower still). However, that's a bit of a gamble, and as soon as your enemy realized what was going on, they'd charge their hulls in the same way that horse fences are charged. The result is that your ship attracts the arcs. Finally, electrical arcs weaken substantially (or require tremendous amounts of energy) as distance increases. Most arcs would want to be measured in a distance of meters in a space battle where distances are likely to be more along the lines of kilometers (or thousands of kilometers). It's not a particularly efficient weapon. Please note that the arcs tesla coils produce are not [electron beams](https://en.wikipedia.org/wiki/Electron-beam_technology), which is a directed form of electricity. Check that out — it might be more what you're looking for. [Answer] **No**. Firstly, as JBH mentions, you need to have enemy ship at lower voltage potential for Tesla coil to work. But, even if enemy ship did nothing, because ships are separated by ideal insulator (vacuum), immediately upon start of your Tesla coil discharge, the potentials would equalize and your Tesla coil would stop working before doing any damage. (you know how birds can sit at uninsulated overhead electrical conductors without any ill effects? They might have different potential at start, but as soon as they touch conductor, they become at same potential, and since they are not connected to ground, there is no electrical loop and no danger) Additionally, for electric current to flow between two points, not only those points must be at different potentials, but those two points must be connected via electrically conductive material. For Tesla coil, for [electric arc](https://en.wikipedia.org/wiki/Electric_arc) to form between two points, the space in between the points is usually gas, which while normally insulator, becomes conductive due to [dielectric breakdown](https://en.wikipedia.org/wiki/Electrical_breakdown) at high enough voltages, so arc can form. Note: while it is theorized in quantum theory that vacuum itself can also suffer dielectric breakdown (and thus become conductive!) near the [Schwinger limit](https://en.wikipedia.org/wiki/Schwinger_limit), the energies required are so high that the humanity has not yet been nowhere near advanced to try to produce experiment to confirm this. ]
[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/180786/edit). Closed 3 years ago. [Improve this question](/posts/180786/edit) I am working on a story set in the present where one of the minor subplots involves a billionaire building a giant stone tetrahedron out in the Nevada desert. While it is not critical for the plot for it to be super realistic, I would like to include some realistic details for background color. * How large can such a structure be made? The current pyramid is around 140m. Could we make it 200? 500? 1000? I assume at some size it would weigh so much it would just liquefy the earth's crust beneath it. * Where would one get the stone? A tetrahedron that is 500m/side would need almost 15 million cubic meters of stone. What stone would be realistic? Still granite/limestone? For this type of project, would someone just contract with existing quarries? * Any thoughts on logistics? I assume for a project of this size one would build railroads as needed from the quarries to the build site, and assembly could be done using pretty standard construction cranes. Any other details I should toss in? * Any thoughts on construction time or cost? Thanks in advance! [Answer] **Consider Mount Everest** Generally speaking, mountain ranges do affect the tectonic plates below them, but they do not "liquefy the crust." So several cubic kilometres of rock **can** be placed on the bedrock, if not on soft soil. The Nazis considered building monuments in Berlin during WWII. What actually happened was the [heavy load-bearing body](https://en.wikipedia.org/wiki/Schwerbelastungsk%C3%B6rper), a big chunk of concrete that has slowly been sinking into the soft Berlin soil ever since. The first step might have to be to remove soil down to the bedrock for the foundations. **Consider the ore and coal trade** In the present day, look at the [MS Ore Brazil](https://en.wikipedia.org/wiki/MS_Ore_Brasil), a large ore carrier with 400,000 tons capacity. Calculate how many roundtrips of such a ship would be required. Of course ships don't go to Nevada, but it gives you a benchmark for the loads which are routinely moved. I **don't** suggest that the stone comes from another continent, just that loads of that size routinely go from mines, to trains, to ships, back into trains, to the steelworks. A 'mere' single-digit billionaire might not be able to afford that. The richest persons on Earth? Probably ... [Answer] **Carve it from a larger stone.** [![sandstone cliff](https://i.stack.imgur.com/v2U6Z.jpg)](https://i.stack.imgur.com/v2U6Z.jpg) <https://www.nps.gov/zion/learn/nature/navajo.htm> Depicted - a cliff of Navajo Sandstone, a prevalent stone type in the Nevada desert. I estimate this cliff to be 250 meters. You might find bigger ones. It is holding itself up. Rather than import and stack blocks, cut and blast away the sides of a larger rock to produce a pyramid shape. It might be rough and so you might need to finish it with and exterior cladding of blocks. Fortunately you will have a lot of material for making blocks. [Answer] If the requirement is full stone you bind yourself. With many modern techniques you can build solid structures and then cover the outside with stone. This makes the inside more practical and can be larger. The height is of less consequence. Normally you need to take care about wind and balance etc. With a pyramid it's relatively stable by my knowledge, although I would still ask a real building specialist. But according to my knowledge, a Burj Khalifa height or higher should easilly be possible as it stands more stable with the weight more spread out. If they include further wind and elements architecture, it should be able to reach incredible heights. The idea has been further thought out in real life to be an actual mountain. <https://en.m.wikipedia.org/wiki/Die_Berg_Komt_Er> This will give you the basic idea, but it might've been hollow, filled with shops, adventures and possibly housing, besides the normal mountain activities. Edit: the link might give you a better idea about materials and such, as well as scaling down might for the costs. [Answer] * Yes. I mean you can made it any height you want. Phisical limitation for Nevada desert would be around 5-7 km. Exceeding this will not liquefy earth, but can case earthquakes, wich would desroy that structure * There are a lot of sandstone (and other sedimentary minerals) in Nevada desert (you know - those spectacular pillars). You would need from couple to dozen of this (depending on size) if you stay reasonable. * You would not need a crane. Yuo may use low layer as a base for your roads/rail network. Exactly like piramids in Egipt were biuld. They used "inverse quarry" road pattern to deliver blocks up to the top. * 10-100 Billons, and 1-20 years of production for 140m - 1000m piramid. This estamation is closer to the top (i.e with perfect oganization 150m piramid can be build in half of a year) ]
[Question] [ There was a nuclear war in my world **Anthropocene**. It caused a mass extinction of numerous animals on the planet, so many I can’t cover them all completely, so I’ll tell you what animals are left: * Rats * Most insects/arachnids * Humans (ofc) * Canines * House cats * Pigeons * Livestock Animals (cattle, sheep, horses, goats, donkeys, pigs, chickens, llamas). * A new, genetically engineered creature called a Trihorner (reptile) Those are basically it. The last surviving animals in the region my world is set. Plants come back as usual, so ignore that, but my question is: with these last surviving animals, could humanity or even nature itself build up a new, healthy ecosystem/food chain? Or all they all screwed? Edit: All micro-stuff (tardigrades and algae) survived, and I don’t care about them for my question When you give your answer and you believe something is lacking, give me a suggestion for an animal that should be added [Answer] Let's remember 2 things really quickly: as far as we know, ever single vertebrate in our world can be essentially traced back to a single ancestor and we had dozens of extinction events throughout the history of our planet. Right after these extinction events, we usually see a large amount of niches available due to the death of the previous occupants and a relatively small number of surviving species, which in cases can result in speciation booms which allow for new species to appear and fill in the gaps. However [that's not quite the entire story](https://evolution.berkeley.edu/evolibrary/news/120901_afterextinction), why? Because some species are capable of faster speciation than others, for example, an animal that has more offspring at a faster rate can undergo changes and select beneficial mutations much faster than a species which has 1 or 2 children every 2 years. So let's have a simplified analysis about the remaining species regarding predation and temporarily assuming plant life is not a problem (because I'm no biologist and not all factors are known about your world, plus you seem to be intending to focus on the terrestrial environment): * The surviving arthropods seem to have no remaining predators other than one another, rats, chickens and an eventual pigeon unless humans too begin using them as a food source. * Rats, unless the dogs and humans start using them as food, only have to worry about chickens and pigs (a pig can and will eat a rat if it's hungry or if it stole the pig's food, a chicken can and will eat a rat period, both these farm animals are omnivores after all), however despite their ability to reproduce fast, it's hard to say if they'd undergo a speciation boom, since lifespan is also an important factor, and a rat will hardly live more than 4 years even in captivity. Rats may eventually eat one another in times of hunger as well. * Your cows, horses, llamas and donkeys superficially have little to worry about other than a large pack of hungry wolves and the now relatively uncontrolled (depending on how the remaining chickens and pigs are doing) rat population (and humans of course, though humans might actually help them survive in the long run by doing what we've done for centuries, save them from other predators so we may be the ones to eat them). * Sheep might be at a greater risk of being attacked by wild dogs, but seem to be on a relatively similar situation as the other large ruminating animals, assuming humans keep using them as livestock. * Goats might be similar to sheep, except they might actually be desired since they've [shown to help controlling rat population in some cases](https://www.pestcontrolnews.com/pcn-interview/). * Regarding pigs and chickens, apparently a mostly similar story, except they have the potential to act as predators (to rats and, if the pigs are starving, whatever they can catch). * Humans seem to have mostly the environment, the rats, an eventual pack of wild dogs and the trihorners to worry about and seem to be better off making their best to keep the livestock strategy going and plant whatever edible grains are left. Keeping dogs close by also seems like a good choice. * The dogs will likely be split into 2 groups:those who keep living with humans and those who go wild, trying to fill the niche of their wolf cousins. They'll likely predate mostly on sheep, some pigs and goats, as well as some chickens and an eventual rat, if they're hungry and it's easy enough to catch. I don't see too many attacks on larger livestock unless the dogs belong to breeds more optimized for hunting and are in large enough packs, and their causalities will likely be predominantly due to failed attacks, human/domestic dogs intervention and potential predation by a trihorner. * The trihorners: you didn't say much about them other than that they're genetically engineered, so I'll work with some assumptions and what was discussed in some of your previous questions: assuming a warm enough climate, your trihorners, assuming they're slightly larger than a komodo dragon, will likely compete for the position of Apex predator with wild dogs and humans, depending on how much these reptiles were engineered to resemble a living weapon. Assuming a deathclaw scenario (created to look like a salt water crocodile and a komodo dragon, both on steroids, somehow had a mutant baby which was feed nothing but protein shakes and more steroids) your Trihorn will easily occupy the niche of solitary yet powerful reptile and occupy the top of the food chain. Dogs might be a problem for the young and the elder, but a healthy adult Trihorn, similar to moose, will likely have no natural predators and will only need to watch out for humans trying to hunt it (or not, depending how much the "on steroids" factor is present in this creature). * The cats: we can easily assume they'll rely mostly on the rats, possibly arthropods they happened to hunt and pigeons for food, as well as maybe the young of some other remaining animals, such as chicks (and maybe baby pigeons as well). They'll likely be predated predominantly by wild packs of dogs and an eventual trihorner which manages to ambush them. The cats will also most likely be divided between those which adopted a more wild and less "human-dependent" lifestyle and those who still live with humans to some degree, aiding in further controlling the rat populations nearby zones of human occupation. They're also good candidates for speciation, being able to reproduce fast and having a decently long lifespan at around 10-13 years in the wild, further allowing natural selection to manifest itself on the wild cat population. So overall, considering the animals only, the environment as is seems to be already able work out relatively fine (although the number of available potentialy predatorial species seem smaller than ideal), assuming plant life is doing well enough and the remaining animals are already present in necessary concentration. If not, we will have problems regarding overpopulation of some species followed by rapid decline in said species, though unless something like the rats runs completely beyond control, I think the environment can regulate itself enough with what's available. What I mean is that, while there are many niches which were left unoccupied, there are still some animals helping in population control,and seeing how mammals all seem to have come from a single ancestor, all vertebrates seem to have come from a single species of fish and we've had a fair amount of extinction events already, we can assume that the most likely scenario is for some of the species still present to slowly undergo specialization to fill in niches left by the extinct land vertebrates. Which species will undergo such speciation is hard to tell, but my bet lies on mostly the dogs, pigs and chickens, as they can all reproduce relatively fast and will all usually live more than half a decade (unlike rats, which reproduce incredibly quickly but don't live as long, though they too might give origin to new species). [Answer] If I remember correctly, the common ancestor of mammals during the times of dinosaurs extinction was something small similar to a rodent. It looks like you are in a similar situation: rats, lacking predators, will proliferate and occupy all available niches, then, to mitigate food competition, they will start specializing on a certain diet, which in the long run will separate them in new species. It won't happen in a few centuries, but that's how it might go. Pigs and chicken, among the livestock, are versatile enough to be able to start their own species trees, too, if they manage to escape human control. [Answer] # Predators are sorely lacking Without predators keeping them in check, anything that rats can eat, they will eat into extinction. Then the rats will starve. Canines - i.e. wolves - are the big exception here. Basically any mostly wild area will be full of wolves, living off of mostly rats, or no animals at all. People, who regard rats as pests, will keep the population in check but not be able to wipe them out (we never have before, have we?). Therefore human settlements will have a constant rat population. This means the area surrounding any settlement is either full of wolves, or a barren wasteland. # You're sure there's no birds? Lot of kinds of birds live in human cities. # Many plants go extinct from the lack of codependent animals Many many plants are adapted to take advantage of the existence of animals to spread. Burr seeds get caught on animal fur, then eventually fall off, the seeds spilling out potentially a great distance away from the source. Berries and fruit are designed (insofar as evolution designs anything) to be eaten, and then the seed survives its typical eater's digestive tract, and gets deposited elsewhere. [Answer] Rats reproduce extremely quickly and can handle a wide range of environments. This allows to expand both geographically, and into a wide range of niches. Their fast reproduction allows them to evolve quickly into creatures similar to squirrels, mice, and other small mammals. Eventually some evolve into creatures similar to raccoons, possums, otters, and even primates. Pigeons reproduce quickly, and without aerial predators, they are able to expand as well. Pigeons eat grass seeds supplemented by invertebrates. With less competition, they are able to diversify somewhat into more roles. Some evolve to eat fruit, others evolve to eat small rodents, and eventually into eating small birds. Eventually their descendants fill most of the roles currently filled by birds. Additionally, pigeons are able to access islands that rats cannot. On these islands pigeons diversify to a greater extant. Large flightless pigeons, similar to dodo birds, are soon the main herbivores on remote islands. With time, they may diverge further, perhaps into something like Emus. House cats protect human farms against rats, which means that they are given many opportunities to go feral. As they become more dependent on eating rodents for their food, their reliance on humans diminishes. Within a few decades bobcat-sized cats have spread across most continents. In time, some evolve into larger cats, similar to leopards or mountain lions. Dog are more domesticated than cats, so they tend to stay closer to humans at first. Feral dogs hang around settlements, eating trash and the occasional rodent. In a few centuries dingos evolve from the feral dogs, and in the distant future dogs evolve into wolves. Feral pigs become monsters, much as they are currently doing in North America. Unchecked, they spread and reshape the land. The other domestic animals find their niches: mountain goats, mustangs, and so on. Chickens are a bit of a wild card. They could do well, but the rats and pigeons will probably get to most niches before they can. I see them spreading fairly widely but not dominant anywhere, into niches such as that held by the wild turkey now. Trihorns, well, I don't know much about them. Reptiles tend to do well in warm areas, so maybe some evolve into something like crocodiles. Because of their urine chemistry, reptiles have an advantage over mammals in desert areas, so expect to see a bunch of lizard-like animals in deserts. Limbless and semi-limbless reptiles have evolved several times, so something like snakes will appear sooner or later. The crocodile-like trihorns make gradually become more and more adept at water life, turning into sea creatures in places with warm water. [Answer] Let's approach this from a r/K Selection standpoint, mostly because there's a lot more detail that could be desired and a *lot* of gestation, etc. numbers to crunch if we did it the full predator-prey population cycle way. * Rat, Insects, Arachnids, Vegetation, & Micro-fauna for r-selected species. * Humans, Canines, House Cats, Livestock, Pigeons for K-selected species. * Trihorner (herbivore, omnivore, carnivore? r/K? I'm using it as our joker) So K-selected species will *tend* to balance themselves as long as r-selected keeps their end of the deal and remains plentiful. Although it is certainly more stable if it forms a predation loop and/or predator-prey ratios are balanced. Humans can also certainly help dampen extinction-potential population swings by selective hunting or just fully integrate as part of the cycle (your interpretation), as was done in [Yellowstone](https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1022&context=polsci_facpub). As for the r-selected: * I'm unaware of any place with vegetation that lacks insects. Even a highly specialized insect predator would have trouble wiping out a strong species if it was K-selected. If your insects are diverse then this is even less likely. * I severely doubt any place with insects would have arachnids dying out. * Vegetation and micro-fauna can have problems but they're generally fine on their own. * Rats... as pointed out elsewhere they're a potential problem. They're not generally guaranteed to self-balance since they're not K-selected. And they're able to dine on most, if not all, the other r-selected species. Luckily, if rats multiply by 4-7 every 3 weeks, then that's about 1 additional rat every 3 days. Given that there is 3 potential predators then any population explosion can be checked by them. In the event you got a mega-colony from being isolated in a predator-free resource-rich area, you'd still need an incursion large enough to be triple the local combined population of predators to be a major ecosystem threat (While obviously a different set of ecosystems, in a modern human city you might have barely any predators but plenty of resources. So rats are only resource bound. Our non-urban areas are more balanced related to rats but also supply resources to the urban areas. Cutting off the resources supplied by those more balanced areas you can get things like [cannibalism](https://www.theguardian.com/world/2020/may/25/us-city-lockdowns-rat-aggression-lack-food-waste)). All of that said though the cat is probably your K-selected guardian of choice for this part of the ecosystem. You probably can't get rid of them, but if you're there to correct an ecosystem imbalance it's not a fight you won't win. Next is the known concern of over-grazing from livestock killing themselves off. Which could wipe canines and humans out. But given that they are *livestock* humans managing them can probably prevent that. Which only leaves the Trihorner to fit into the web. They could very well destroy it as an r-selected so let's make them K-selected if that's alright. If they are: * **Herbivores** our livestock have a problem with too much competition. We'll have to hunt them. * **Insectivores** (arachnids included) we're probably good. * **Carnivores** it'll depends on what they eat. Canines or pigeons makes things more stable. Rats relieves humans of some of the burden. Livestock is probably perfectly okay since we'll try to protect them but will fail from time-to-time. Cats would maybe be pretty bad. It depends on whether canines preferentially hunt cats over rats. Eating humans is not great but probably moderately okay. It replaces the Apex Predator with something with less intelligence to manage the population swings. But it does knock out an omnivore so as long as livestock isn't terribly self-sustainable in the wild the cycle should be okay. * **Omnivores** would just be bad, especially if they were an Apex Predator. If their size allowed them to hunt canines and rats preferentially, then no problem. The biggest problem is that they have no extinction clause in this herbivore-dominated ecosystem. Anytime you might have a typical K-selected balancing, predator-prey ratios won't allow it. Anytime the prey is almost wiped out they won't dial back from hunger and reproduction loss, because they can still eat plants and insects. The only check they would have is a Predator Explosion due to the abundance of themselves as Prey. But they would still strain every tier of Prey underneath them. * **Apex Predator** (see omnivore and carnivore) * **"Other"-vore** (fructivore, etc.), specialization makes this less likely to survive as it hinges on the survival of something else. The more specialized the less likely to survive (a "problem" that is, in general it'll be more efficient at what it does and flourish). However it also is highly unlikely to mess with the rest of the ecosystem, probably at most it would knock itself out with its Prey. **So will this food chain survive?** If the trihorner isn't there, then **probably**. With it actually present though it will need to **meet some conditions**. Maybe strict preferences in diet, maybe specialization in hunting a particular insect, maybe it eats all meat except human meat. That said, **humans, as always, will have an amazingly large potential to upkeep or royally screw over the ecosystem.** [Answer] Plants (and fungi which you missed) are the most important part of the food chain as far as multi-cellular macro-scale organisms are concerned. You cannot claim such widespread destruction of the food chain if plants are still there. Many animals would die but with plants and insects around, the basis of the food chain itself would still be there. Omnivores, herbivores, and insectivores would be fine. The food chain would be pruned, but not destroyed. It's just different than what it was before. It therefore wouldn't need to recover and should just regain its diversity in time as vacant ecological niches are re-occupied. [Answer] I will try to be as brief as possible! Insect farms could be made. Similar to these in China and south east Asia. Same goes goes for dogs and cats, similar to the food in Vietnam and the two Koreas. Although feeding for the dogs and felines will be required. Therefore, these two would be a luxury food. Genetically engineered plants will be a must if you want to re-establish settlements then civilization, similar to what the nomads did. ]
[Question] [ A worldwide pandemic has killed the world's dogs and their cousins the wolves. In sheep farming countries, dogs have been and still are an invaluable aid to sheep farmers. Some breeds will herd the sheep others guard the flock from predators and rustlers. Sheep are grazers and they don't take at all well to factory farming. They need wide open spaces to roam and forage. This is affecting wool and food markets right now and something has to be done. Some bright spark suggests training the sheep instead of the dogs. This is crazy for several reasons, the main two are: (1) sheep are stupid (2) instead of training one dog for 6 months and then getting years of work out of it, you would have to train thousands of sheep. The most popular idea in this age of electronics is that the sheep should be be radio-controlled. **Question** Assuming that we don't want to do anything nasty to the sheep and we want an inexpensive radio-collar for each, how practical would it be to call the sheep home after weeks or months of grazing for shearing, medication and other necessities? How could they be steered in the right direction and also persuaded to move - again without animal cruelty? [Answer] **Basic Reward Training** Sheep aren't stupid and can give a lot of dogs a run for their money. A radio collar emits a beeping noise. To the sheep, this means a load of food they really like better than grass has been dumped in the sheep yards. The sheep will learn what the noise is and what it means pretty quickly and you can watch them actually run all the way back to the yards I hand feed my cows and sheep for this exact reason. They come running when I call and it's easy to get them in for worming or shearing. Plan B is radio controlled access to water. If you shut off the water where the sheep are and the sheep know there is water in the yards, they'll all move back to the yards to get water. Plan C is training another type of animal. As the move Babe showed us, pigs can be trained to herd sheep. [Answer] [![enter image description here](https://i.stack.imgur.com/fXwkn.jpg)](https://i.stack.imgur.com/fXwkn.jpg)Sheep will normally follow a flock leader, traditionally a castrated ram was used for this role, known as a belwether (they carried a bell). This is still done in many parts of the world. You don't need to control the whole flock, just the belwether. Simple reward training should work fairly well. My cat can be summoned home by radio control using exactly this means. He has a Tabcat tracker on his collar (blue disc in image) which beeps when I press the remote. I don’t have to look for him as he knows the beep means 'food reward if I come back now', so as soon as he hears it he hurtles back in from whatever hiding place he has been lurking at in the garden. Sheep may not be as smart as cats but would probably get the idea. [Answer] If you are trying to create a new solution for it in order to really get the zero animal cruelty requirement met, that will take some R&D. I think it's the way to go, but while you don't reach that mark, let me suggest using some technology that already exists. You could tie some Halloween props to drones. When the time is right, the drones will approach the sheep from the side opposite of home. The sheep will come running. [![A dementor prop tied to a flying drone.](https://i.stack.imgur.com/y1zdu.gif)](https://i.stack.imgur.com/y1zdu.gif) Might be cruel because the sheep will be scared (more than what they'd be with a dog). However the cruelty involved here is minimal, and to make up for that you will also be giving them some exercise. If you want to be creative and less cruel, you could replace the dementor props with plush dogs. Bonus if those can bark. Just fly the drones around the sheep in a way that dogs would. Might be harder to set up than the dementors, though. --- Once you have solved the problem with minimal cruelty as above, and got the time to invest into R&D, you could work towards improving and repurposing Sony's pet dog, Aibo: [![Sony Aibo, a robotic dog.](https://i.stack.imgur.com/wv4sW.png)](https://i.stack.imgur.com/wv4sW.png) [Answer] If you can check the sheep brain for activity when they want to go "home", you can simply put an electrode in their brain stimulating that area. A wire goes outside towards the RF colar (you want as little in the brain as possible). That, or intensive pavlovian training with music, but that might be difficult. Electrodes in the brain are less dangerous than you might assume. In progressive Parkinson they sometimes put rods through the brain towards the subthalmic nucleus to stimulate it in both hemispheres (<https://mayfieldclinic.com/pe-dbs.htm>). It is invasive, but smaller electrodes will be fine if not rejected in the first weeks. You don't need to do this with every sheep and risk infections and such. Just a few, preferably socially high ranking insofar they have them. The proverbs about sheep blindly following each other is very true, to the point of whole herds (in very rare cases) killing themselves because they followed another sheep that then accidentally fell off a cliff. So with a few starting home, you might have the desired effect. The "colar" can be put under the skin. The reveiver and the electrode might even be powered by the sheeps body alone with some clever techniques, never or rarely requiring a battery change. Alternatively you might try a different approach. Robo sheep. Sometimes introducing the robo sheep and then trying the other sheep to follow them. Though I don't know enough about sheep social behaviour if they would automatically follow unknown robo sheep, you might enhance this with pavlovian training of a few to follow them with the promise of food. If this has happened once or twice for the whole herd, it might already become a group behavior to follow robo sheep. [Answer] My advice would be invest in stock for Boston Dynamics. <https://www.businessinsider.com/boston-dynamics-spot-robot-dog-herding-sheep-in-new-zealand-2020-5> for an article on their robo-dog (Spot!) herding sheep in New Zealand. ]
[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/178858/edit). Closed 3 years ago. [Improve this question](/posts/178858/edit) I want to create a gimmick world, that is ALMOST entirely covered up with massive mesa/canyon-like structures : flat-topped elevation ridges or hills bounded by steep escarpments. The space in between large plateau would naturally be canyons. What are my options ? [![enter image description here](https://i.stack.imgur.com/7vRD1.jpg)](https://i.stack.imgur.com/7vRD1.jpg) [![enter image description here](https://i.stack.imgur.com/aqFzA.jpg)](https://i.stack.imgur.com/aqFzA.jpg) [Answer] That kind of mesa (or *tepua* if you're in South America) forms by erosion of a plain. Typically, you'll find a somewhat resistant upper layer, a number of relatively soft (or easily eroded, for reasons other than mechanical properties) layers, all sitting on another resistant layer. It seems pretty unlikely you'd have this kind of terrain *all over* a planet, because it's a near-endpoint of eroding away a sedimentary formation, and the "softer" rock has to be uplifted to give the necessary runoff zones -- as well as, for some period, having either enough rainfall (upslope) to provide the runoff, or an ice dam or similar impoundment that can lead to catastrophic erosion. [Answer] On Earth mesas are caused by localized forces of erosion on specific kinds of ground. This is not something you can really get on a planetary scale, but there is another force that might form mesa like structures, and that is magnetism. [![enter image description here](https://i.stack.imgur.com/pxo4u.png)](https://i.stack.imgur.com/pxo4u.png) ## So, use a Magnetar [Magnetars](https://en.wikipedia.org/wiki/Magnetar) are a kind of neutron star with ridiculously powerful magnetic fields that are quadrillions of times more powerful than the field surrounding Earth. The big difference between using a magnetar and relying on erosion is that the magnetar affects your whole world pretty much the same; so, two places in two different regions will still experience the same kind of forces. The magnetic field of the magnetar would have a similar effect on the terrain to tidal forces; however, instead of affecting all matter equally, it will only pull on the ferrous elements in your planet. As such, anywhere you have a lot of iron, that iron will raise the ground up and pull together into mesas whereas less ferrous areas will be stripped of what iron they do have and sink down lower giving you your mesas and your canyons regardless of any other local geological happenings. [Answer] For this situation to be viable (people only living on the top of the plateau), you would need a reason for the valleys between the Mesa to not work as a plain, while the top of the Mesa still does (because you need to at the very least grow or hunt food). Because of this, a desert climate wouldn't make sense (Mesas would also be desert), and we can also rule out lava. What I would suggest is deadly creatures or fast-moving water. The societies that form would be cool, bridges that are built would literally become arteries for larger cities, and I could see some primitive gliders being implemented to transverse the area. [Answer] You have a lot of options, but making most of the planets looking like that is still very weird. **Karst** Some rocks are soluble (e.g. limestone) and when they do, the insoluble rocks were left behind, often forming peculiar formations. Personally, I find this formation the most fantasy-looking. [![Zhangjiajie, China](https://i.stack.imgur.com/Arg7e.jpg)](https://i.stack.imgur.com/Arg7e.jpg) *Zhangjiajie, China* **Volcanic Plateau** If volcanic activity produced sufficient quantity of viscous lava, they may solidify in plateau-like formations. [![Pajarito Plateau, United States](https://i.stack.imgur.com/xPDBB.jpg)](https://i.stack.imgur.com/xPDBB.jpg) *Pajarito Plateau, United States* **Large Igneous Province** Extremely large volcanic activity may also form an igneous province. It's like volcanic plateau, only at much larger scale. [![Deccan Traps, India](https://i.stack.imgur.com/jRcgh.jpg)](https://i.stack.imgur.com/jRcgh.jpg) *Deccan Traps, India* **Fjord** Basically canyon, except carved by glaciers. [![Norwegian Fjords](https://i.stack.imgur.com/mwjUt.jpg)](https://i.stack.imgur.com/mwjUt.jpg) *Norwegian Fjords* **Mesa** Finally, the good old mesa. They are formed when softer rocks were eroded, leaving the harder rocks as "caps" overlain by softer ones. [![Blyde River Canyon Nature Reserve, South Africa](https://i.stack.imgur.com/5ug7u.jpg)](https://i.stack.imgur.com/5ug7u.jpg) *Blyde River Canyon Nature Reserve, South Africa* Now that I've answered the question, I can move on to this: **does it really have to cover most of the planet?** If this is going to be the setting of a story, only the place where most of the story takes place needs to be mesas. I really doubt you would need to use the entire planet for the story, but in case you do (maybe you're writing an anthology or a really long story), it would actually be boring if everything looks similar. Personally, I would avoid [single-biome planet](https://tvtropes.org/pmwiki/pmwiki.php/Main/SingleBiomePlanet). [Answer] I would say it is not possible for an entire planet or at least not for an inhabitable planet. But taking “world” to mean a very large area (e.g. the Roman world) rather than an entire planet it might well be possible. Imagine a planet with a very dense atmosphere and a lot of volcanism. An extensive area of high plateau might form and with the right rock strata, climatic conditions and enough time could be dissected into a mass of large mesas that you are after. If the canyons were deep enough it might not be possible to cross the intervening gaps because of the pressure and gas concentrations in the lower areas. Imagine if the pressure at the top of Mount Everest was 1 bar. At sea level the air pressure might be 3 bar or more. And with an increased level of carbon dioxide that was just manageable at Everest height might well be toxic at increased pressure and concentration in the lower areas. [Answer] This world could orbit an orange dwarf star. what usually causes geological formations, believe it or not, is tidal forces, albeit only one factor, and one of the main ones due to gravity tugging on a body a causing geological formations to begin forming. since worlds around orange and red dwarfs are much closer to their parent stars, this would entail much more active plat tectonics and tidal forces generating mountainous Terrain planet-wide. The planet could be smaller than this one too, thus making it be more mountainous. and such a would would have white or gray colored skies and blue plant-life if around an Orange dwarf. So all in all, this world of yours is going to be an amazing place to visit. ]
[Question] [ One issue with a laser sword (light saber) is stopping the light beam at a desired length, There have different designs to re-create a similar effect using lasers and plasma, usually with some sort of internal coil or a bar running the length of the sword. The idea I have in mind will work best with lasers and to stop the laser will be a drone at the tip of the sword acting as the mirror to reflect the laser back and give it length. The drone can use the laser to lock onto its position and even use some of the energy to power itself. It would limit the strikes to only along the length of blade and not the tip. Is this possible that a drone could be used as the reflector end of the light sword? [Answer] **Frame challenge:** instead of reflecting the beam back to the hilt with a technologically complex drone, just use an opaque beam absorber that's affixed to the hilt. As other answers have pointed out, reflecting the beam back toward the user adds unneeded risk - if the reflector gets misaligned even a little, the user could accidentally chop their own hand off. Additionally, the beam emitter now has to perform double duty as a beam absorber, adding complexity to the apparatus. If all you need to do is halt the beam, you just need an beam absorber instead of a beam reflector. A drone is also a rather complex and fragile way to keep the reflector/absorber in the correct position. It would be far simpler and more reliable to just attach the reflector/absorber at the end of a blade-length arm which is affixed to the hilt (sort of like a selfie stick). This would mean the sabre is no longer omni-directrional, as you must swing the blade with the arm in the back. This shouldn't be a huge issue, though, since I can't think of any regular sword that allows you to cut in any direction. If you really need to swing the sword in any possible direction, some control electronics could be implemented to rotate the arm away from the direction the sword is swung, ensuring that the blade rather than the arm hits the target first. This rotation mechanism will be far simpler than the control electronics needed to keep a drone hovering at a precise spot in 3D space. [Answer] **I want my light saber energy going *away* from me.** The problem with reflectors is that they turn energy going away from me into energy going towards me. I do not want that energy back over here. If the drone reflects it perfectly it will go back into my lightsaber doohickey and then what? All the stuff in that thing is meant to emit energy. Now I also have to have something in there that absorbs energy? It already hangs down from my belt in an awkward way and now it will have to be bigger. People will think I am trying to compensate. Plus if I run it will bounce uncomfortably, and I might run. Worse is when I get excited, or something jostles the drone. Now when it reflects it misses the doohickey and hits my lightsabering hand and there go the knuckles. I will need a reflective glove. Or it misses doohickey and hand entirely and hits my pants or my foot or my Ewok sidekick. Nay; nay - we will leave the drone for use during welding mask-wearing Force using saber sessions. We will keep the saber svelte and Ewoks and Jedi pants safe. [Answer] You have two main issues: if you are using a sword, you want to swing it around and maybe even point it to your target. 1. **Swinging it around**: due to the geometry of the sword, the tip will be always moving around faster than your hand. This means that the drone will have to chase your hand movements quickly and precisely, no matter how they are. Else if you lose it you lose your blade. 2. **Hitting your target with the tip of the blade**: obviously if you do this, you want the point to penetrate your target. But the point in this case is the drone. If the drone is passive from this point of view it's like hitting your target with a retractable blade: good for a Hollywood movie, not for a real fight. If instead the drone is active and can go through your target, why are you bothering having a laser when you have piercing drones? Moreover your drone is the weak spot of your blade: as soon as your target can incapacitate or disturb it, you are left with no sword. ]
[Question] [ Fireflies are amazing little insects. They have the ability to produce a pulse of light without the help of a symbiotic relationship with bioluminescent bacteria. This works via a chemical reaction which involves a light-emitting pigment called luciferin [L] and an enzyme called luciferase $$\text{luciferin} \ + O\_2 \ \_\overrightarrow{\text{luciferase}} \ \text{Oxyluciferin} \ + \text{light}.$$ **So is it biologically plausible for a vertebrate to have this ability?** Let's say it has a special light organ on its head and uses this ability to communicate to other members of its species (similar to a semaphore) and/or to cause a short term dazzling effect that blinds a predator for a few seconds/minutes. It would be something like how this guy does it (he's from monster hunter world): ![](https://i.imgur.com/OkHaMVN.gif) [Answer] There are fishes living in the depths of the oceans which are capable of producing [bioluminescence](https://blog.ucbmsh.org/department/zoology-department/bioluminescence-in-fish) for the sake of mating and attracting prey. [![bio-luminescent fish](https://i.stack.imgur.com/8GQfo.jpg)](https://i.stack.imgur.com/8GQfo.jpg) Fishes are vertebrates, and apparently have been able to evolve this feature. Maybe they use slightly different chemical paths, but the result doesn't change. They emit light. [Answer] **Sure!** As fans of [Finding Nemo](https://www.youtube.com/watch?v=fMTHrvskSW8) know, the anglerfish is a vertebrate that can glow. The chart below shows other fish (vertebrates) that have evolved bioluminescence. As [the source](https://evolution.berkeley.edu/evolibrary/article/fishtree_05) for that chart says, it's not just a fish/firefly thing: > > Lots of non-fish species use bioluminescence as well — some bacteria, > sponges, jellyfish, crustaceans, segmented worms, squids, sharks, and > even plenty of terrestrial species like fireflies. All bioluminescence > is caused by a chemical reaction. Some of these organisms produce the > necessary chemicals themselves, while others, like the anglerfish, > rely on the help of symbiotic bacteria. > > > [![Chart of marine species that can glow](https://i.stack.imgur.com/yD8hu.gif)](https://i.stack.imgur.com/yD8hu.gif) Broadly speaking, there are two different ways of making a creature glow: either the critter produces light by itself (as your equation demonstrates) or it gets some help. The Anglerfish uses the latter approach. It's developed a symbiotic relationship with bacteria. In your world, there's no reason that a non-aquatic species couldn't develop a similar relationship with a glowing bacteria. [Answer] A vertebrate to evolving from a firefly isn't going to happen. If it did, it'd have to be an incredibly convoluted process which involves degrading the evolution to where vertebrate can evolve from that. Theoretically not *impossible*, just not likely. Also something that isn't going to happen on Earth because evolution moves forward, not backwards. It *is* possible for a vertebrate to have the biological process that fireflies have to produce glowing light. It's an organ which functions independently of vertebrate status, so there's nothing stopping a vertebrate from having it. [Answer] Most land-living vertebrates have too thick skin to make this bio-luminescent light possible. The fact that of the vertebrates cited above only fish specimen have this feature supports that. Fish have thin skin as they don't have to protect against water loss at the same degree as the land-living creatures. Obviously insects with their chitin exoskeleton have the "advantage" as chitin allows for a thin but strong build. ]
[Question] [ Let's say we have a small civilization that built a wall (Great Wall of China as an example, but with no open sections, all contiguous, besides gated castles) of 300 miles all around their country, totally closing access to their mainland from North, East and South and having its west border facing a sea. That civilization was able to domesticate a sort of flying lizard that enables them to have a small air cavalry. As the flying lizards don't have a large autonomy, they have to be used defensively only. They also found, by raw chance, that by leaving stale bread around moldy lemons they were able to get a kind of mold that, if powdered and eaten, reduces inflammation and helps fight infection. As well they invented repeating crossbows with poisoned arrows. The poison they use paralyzes a man or animal, and stops their hearth in two or so minutes. Crossbowmen use those to man their walls and shoot at any approaching invading army. Their flying lizards cavalry is also used to drop volleys of those poisoned arrows from above along with a kind of flammable liquid, similar to Greek Fire. They also have Trebuchets that launch explosive balls with that Greek Fire of sorts. Those flying lizards were domesticated by a tribe from the central hills on that country, and no other tribe was able to ever mount the lizards, as they are raised along their riders since their infancy. So, only riders from that tribe are able to successfully mount the flying lizards and take them to combat. That civilization produces all food they need inside their walls, so they don't need to trade with neighboring civilizations for survival, but they keep a flourishing trade through their gates to a series of special open market cities along the walls were foreign presence is allowed. Foreigners are not allowed past those border cities, and if they get caught inside the country the punishment is death. They have a very strong cultural unity, based on a religion that proclaims them as the single chosen people of a God that, for them, is the creator and ruler of all things. (let's say like ancient Israel for example) That religion also teaches them if they mix with foreigners they would break their covenant with their God and will suffer the fate of being conquered and enslaved by foreign powers. Their technological and cultural level (and that of their neighbors) is equivalent to very early Middle Ages (5th century AD) and their region is like the Levant, a very populated and ancient region with plenty of markets and with at least three large and powerful Empires fighting for hegemony there. My question is: how would that small civilization, while strong, and very well defended and entrenched, be able to avoid external powers to steal their knowledge, especially their flying lizards, the Greek Fire and the antibiotic mold medicine, through spies getting in or deserters going out? There is no magic whatsoever of any kind (not even miracles through praying or any other ritual). [Answer] As AlexP mentioned in the comment the Byzantines were able to keep the Greek fire mostly secret despite using it for centuries at significant scale. Arabs also had access to fire weapons to some extent. The technology was (I think) originally developed in areas that were taken over by the Arabs so not much the Byzantines could do about that. But they still largely succeeded and the Greek fire is assumed to have been superior to its Arab and Chinese counterparts. We do not really know because... secret. Anyway the key was that it was a military secret of great strategic value. Its manufacture and use was controlled by the state and the secrets related to its manufacture and use were really only known by a small number of trustworthy men working at secure facilities under supervision. Actual weapons would be guarded by the military forces they were given to. And they would not be given to just anyone. And of course nobody in the field would have no idea how any of it was manufactured or the specifics of the design. At most they might know how to fix some common issues with the fire siphons. All your "secrets" actually fall into this same "military secrets with strategic value" category. Greek fire was already handled. Single secure facility manufactures everything. Few people work their and they are constantly guarded. Deliveries to units using them are guarded and protected. Storage is guarded constantly. They are only taken out when use is specifically authorized. And as soon as they are not used they are all put back to guarded storage. Used, broken or expired weapons are transported back to that secure facility with the same secure system that brought them out. There is an emergency disposal plan for destroying the weapons to stop them from being taken by enemy if a fort is taken. Although reasonably capturing such weapons is not very useful. People do not have the ability to do chemical analysis and figure out the formula. This is even more true for antibiotics. There is no need to tell anyone they are made from mold and no real way for anyone to figure it out by inspecting the finished product. So just have a secure facility for manufacture and make sure the antibiotic is properly obfuscated by mixing in things with strong odor, taste, and color. Also disguise texture by grinding everything to fine powder and pressing it into tablets. You probably want to additionally control distribution and use. Just make it into a strictly regulated government monopoly. Good source of money during times of peace and keeping price high and access limited keeps bacteria from getting resistance. The flying cavalry is either going to be no issue or impossible. If taming the lizards is difficult, then just keeping them restricted to elite military units is enough. You need significant amount of lizards and trained people to copy the airborne cavalry, so as long as access to both is restricted within your borders there is nothing outsiders can do unless an entire unit defects. And if the lizards are common outside and taming them is easy, you have few years after anyone sees your airborne cavalry and realizes it can be done before you lose your monopoly on this tech. There is one additional thing. The most obvious use of the airborne cavalry would be for reconnaissance and for carrying messages. Neither of these requires flying near outsiders. Messages should be carried between special towers in areas forbidden to outsiders guarded by soldiers. Reconnaissance can be done at fairly large altitude. You want to be warned of movements of armies, not see individual people. So if you camouflage the rider and his equipment with proper colors so that everything blends to either the lizard or the sky, it should be difficult to be sure there is a rider. So you can at least try to keep it secret. [Answer] **Mitigate the damage of defections by strategically dividing out the tasks among many people** Each recipe/technology is complicated, and your civilisation divides out the work so that no one person knows the full process. This means a large number of people must defect to the same rival Kingdom for the secret to become known. There are a number of ways to further increase secrecy: * some people contributing to a vital process don't even know they are. For example a farmer: their herb is one of 12 vital ingredients of Greek fire. They think they can pay their taxes to the king in this herb because the princess is a notorious foody who likes to season her tea with it. They will never defect because they have no idea they have a secret to sell. * some people believe they are part of a vital process but their work is a red herring. One man spends his life smithing precise metal studs that he believes are implanted in the ear canal of the lizards to confuse their senses and make them docile. But when the palace receives a shipment they secretly melt it all down to make nails. If this man defects he will be 100% convincing because he honestly thinks he's telling the truth, but will just be wasting the resources of the rival Kingdom. * each process uses the input of dozens of professions, with a small number of overseers who know how to assemble the final product. These people are very well looked after to prevent defection, in fact they would probably make up the nobility or the royal family. Knowledge of these state secrets may even be the reason that they are nobles in the first place. [Answer] **No plan of operations extends with any certainty beyond the first contact with the main hostile force** *- Helmuth von Moltke* It doesn't matter how well you plan your defences, how many contingencies you put in place, how harsh the punishment is for breaking the law. You will always overlook something, and eventually the secret will get out no matter how hard you try. You can minimise the option, but never eradicate it. Especially defection or betrayal will be a concern. Even when your main religion dictates your people are far superior to the outsiders, due to human nature some people will be more, and some people will be less devoted to it. There will be a plethora of reasons someone could betray their country, almost too many to list. You could minimise this risk by limiting the amount of people with detailed knowledge about the technologies, but it will never be fully 0. Your biggest problem is that your technology is desirable. If it is effective against your enemies, others will want it. This makes the knowledge worth quite a lot, and the more something is worth, the more people are willing to risk for it. [Answer] The major concerns would be the existence of such place. China was able to build the Great Wall with a population of around 160 Million while the propose country would optimistically reach 1 Million (the entire country would have an area comparable to modern day Beijing). Regarding the actual question, should be fairly safe to maintain the secret around the major discoveries. All you require is having limited access to the recipes (for the antibiotics and Greek fire) and strict control of the individuals having such information (maybe consider them as a higher-ups in the clergy ranks). Also a low level of literacy would help with this. For the lizards, the easy way would be the usage of drugs (same logic as above for the recipe and only limited quantity shared with the handlers). Making sure that without such drug or the antidote the lizard will die or became extremely aggressive. This however does not cover the risk of eggs being stolen but this should be covered by a guarded hatchery of some sort. [Answer] A practical answer to your question would be quite similar to how information is protected against espionage in the real world. Military hierarchy, compartmentalisation of information, distribution of tasks, different levels of access to information, proper screening of people before promoting them to posts with more control and access to information. And it works pretty well, or atleast fairly well enough for most militaries in the world to hold atleast some secrets to themselves. Maintaining confidentiality of military secrets is a multi-billion dollar industry, so you can imagine there's tons of research on it, although not all of it is available in the public domain. For starters, try defining your attack surface more precisely - what are various forms of information theft you are anticipating, who are the potential bad actors, what powers do they have, so on and so forth. Given that it's fiction, you may not have to go into too much detail, but you always can, since it is possible. Agreed this is not a very interesting solution, but it's the most practical one in a world sufficiently similar to ours - as shown by the fact that it's what is used in the real world. [Answer] **They cultivate an image of pathetic lameness.** In their (tightly controlled) interactions with outsiders, your people go to great lengths to appear pathetic and diseased. Their clothes do not fit and hang shabbily off their misshapen bodies. They smell like they have rolled in something nasty, because they have and they are trying to scratch it off of themselves with nails left long for that purpose. They speak as though they are fighting a losing battle with mucus. Interactions take place in a sort of reverse [Potemkin village](https://en.wikipedia.org/wiki/Potemkin_village) built to ensure the impression of inbred filthy gurning backwardsness. No-one wants to copy these folks or be like them in any way. They are the laughingstock of their world. The name of these people is used as an epithet worldwide. No-one wants to invade and steal their stuff either because it is dirty, infested with parasites, and worthless stuff anyway. --- The actuality of your people is far different. Their little charade (which they pronounce to rhyme with odd, not raid) is a source of national pride and the people chosen to represent them are skilled actors, in possession of much soap and excellent showers. Sometimes these folks will put on their act on stage, for the education and entertainment of their people. ]
[Question] [ In my world, there's a tentacled race of amphibious creatures. They evolved in water, but can also survive on land. They're roughly human sized, but they're boneless and they move around on six flexible tentacles. They use their tentacles both to carry themselves and grip any objects. So what would be the best weapon for these creatures to use - i.e. if there was an army of them on land, what would be the default type of weapon employed? Some details about their tentacles: Fully extended, their tentacles can reach up to twelve foot long, but they lose all leverage at that length. In general, the tentacles are very good at pulling, but very poor at pushing. The tentacles contract. They have muscles designed for dragging prey towards them, but not for pushing or thrusting with a blade. Their tentacles have suckers, granting them an incredibly strong grip. They move over land by dragging their torsos with their tentacles. If they are using all six tentacles to hold something, they become effectively immobile. They have no fingers or digits; their tentacles are very flexible, but not very dexterous. They cannot handle any equipment that requires fine operation (so no bows). Their bodies could be outfitted in armour, but their tentacles can't be - simply because you can't properly fit any sort of sheathing around them. In battle, it means that the tentacles could be very exposed and vulnerable. Against unarmed prey, they'd hunt by ensnaring the prey in tentacles and squeezing the life out of them. However, as part of an army facing steel weaponry and amour, relying on that tactic would go very poorly. They'd need some sort of weapon instead. I originally imagined that they'd wield spears to take advantage of their reach, but boneless tentacles just wouldn't be very good at thrusting a spear. In human weaponry, generally it's designed so that all of the strength comes from the elbow and shoulder, but these creatures have neither. They have a completely different bone structure from humans, so I have to imagine that their weapons would look completely different. Assume low fantasy / medieval technology level. [Answer] You ask about an army of such creatures, so realistically their weapons will be determined by the tactical and strategic doctrine of the army. How one of these creatures might fight individually is not going to be the same as how a group would fight, and how a group would fight is not the same as how a professional army would fight. For example- see the Phalanx formations (Google it). Rows of men would stand five or six deep, tightly bunched together and with shields in front, while those behind held spears of between 5 and 6 meters in length stuck out in front. The result was a literal wall of spears that would catch any attacker three or four meters before they got close enough. Excellent for deterring disorganized individuals and cavalry. The Roman army used soldiers called Hastati as the bulk of their front-line units. These were lighter armed and armored swordsmen who also carried two javelins called pila. They would throw their javelins as they advanced on the enemy, shocking them, and then engage in sword combat with the short sword called the gladius. Being lightly armed and armored, these Hastati could then maneuver or disengage as needed to bring the more heavily armed and armored second and third lines of Principles or Triarii to bear on the enemy after they had already winded themselves. My reactions to your scenario are that: 1. Your octopus creatures have a long reach but are not particularly quick, so the only thing that reaching out twelve feet does is give your enemy the chance to cut off a tentacle. 2. No matter how long their arms are, the laws of physics and the mechanics of leverage mean that they're not holding anything particularly heavy that far away from their body. (Try holding anything at arm's length for 30 seconds.) 3. They cannot use crossbows or bows, but that does not prohibit them from using simpler ranged weapons like javelins. One idea would be to give each creature two or three shields that they use to defend aggressively, and dart out quick jabs with a dagger or short sword to exploit enemy mistakes or weaknesses. Assuming they need something like six tentacles to move around, they could hold two or three large shields close to their bodies and then hold a short sword and a javelin ready to strike out. The Javelin can also be used as a short spear. Another novel idea would be to have a line of shields in the front row, and then have the creatures in the second row exploit their long tentacles to raise themselves six or eight feet above the front row just long enough to throw down spears at unsuspecting or vulnerable enemy heads. [Answer] I think that two classes of weapons would work for your tentacled warriors. The first would be things that attach to their tentacles and let them slash or pierce. So spiky cuffs, though I don't know how you make sure they stay in place. They could swing and grip targets, puncturing them with the spikes. Similarly, a knife with a slashing edge, pointed on both sides, gripped by a handle -- similar to a pastry knife. They could swing their tentacles around, slashing at their opponents. They could these weapons in as many free tentacles as they had -- those not needed for locomotion. The second kind could be infantry flails. [![enter image description here](https://i.stack.imgur.com/JNGTX.jpg)](https://i.stack.imgur.com/JNGTX.jpg) They could grip them with two tentacles and attack by raising one tentacle and lower the other. They could also use the handle to defend themselves from some attacks. I don't think other styles of flail like weapons would work for them --- like morning stars (the stick with a chain connecting it to spiked balls). I think they'd be as likely to smack their own tentacles as their opponents. [Answer] Spears can potentially be an effective weapon for them, but not as you imagine. They would hold the spears behind them, and hold them overhead. They could then contract their tentacles to thrust forward quite forcefully. Perhaps some slits in their armor could use with aim. The spears would be longer, but quite effective, especially when combined with shields in other tentacles. Other than that, you would probably see an increase of (cart) mounted weapons. Large ballistae would be able to be operated by them, as well as smaller cart mounted bows or crossbows. Even tripod mounted (static) crossbow contraptions would work for them, if their dexterity wouldn't allow them to carry crossbows normally. Aiming could be done not by holding the weapon with a tentacle, but by resting it on one or two, and flexing/relaxing them to increase their thickness for a finer control. Also if mounted combat is an option, a tentacle creature on horseback, flailing around daggers or swords at anyone coming in range would be a very painful encounter for anyone not sufficiently armoured. Optional spears strapped to the horses saddle. I'm not sure if flinging anything would work well from them. If anything, this would be done from behind by contracting the tentacle while flailing the tip upwards. If perfected, they could use a range of small thrown weapons like throwing knifes, darts, or rocks. Even spiked objects like sea urchins (modified for grip) could work, to keep with their theme. As for tactics, since they evolved in water, they would try to draw the battle to the sea as much as possible. Their defences would be significantly stronger in lakes or seas. Guerrilla attacks would be useful for them as well, as they can infiltrate a settlement covertly through its water source, and I imagine they would be able to move and kill fairly silently. [Answer] **Against Humans: Shields and Grappling**. When fighting an opposing army of humans, we use a variant of our natural strangling behaviour. The strategy is to isolate the enemy front line from the guys behind them, overwhelm that front line, and then repeat. Every soldier has say four shields and four dagger-like weapons. They are attached to the tentacles such that those four tentacles can be used for locomotion. We stay low to the ground while shielding from above, and take advantage of our natural abilities to squeeze behind the front line. [![enter image description here](https://i.stack.imgur.com/IJhBF.jpg)](https://i.stack.imgur.com/IJhBF.jpg) Note to armorer: Make shields flexible. This is effective because human weapons are usually designed to fight another human. Being low down actually makes us harder to hit from further away. Once we have isolated the front line we rear up and keep the second line busy with our shields, while our second, third, and fourth line overwhelms their (now surrounded) first line. They cannot swing a sword/spear at someone (or five someones) clinging to their chest and their armor is useless since our many nimble tentacles locate the neck and armpits and stab through there. Note to armorer: Design shields so they can be moved up/down the tentacles as required, to prevent them getting in the way during grappling. ]
[Question] [ I'm writing a story where an intelligent zombie society has defeated humans and won. The zombies are the main characters in this story. These zombies: * Have human intelligence, emotions, and remember their lives before becoming zombies * Have a nearly impossible to resist urge to eat human flesh. Brains are not actually preferred like most zombie cliches. * Animals and plants do not give them any nutrition, and tastes pretty bad to them. * Zombies will slowly regress into mindless monsters if they do not eat human flesh. The speed at which this occurs depends upon the amount of flesh eaten last time, the time passed, and the individual willpower of the specific zombie. My problem: If all humans become zombies, then zombies no longer have any food and therefore all is lost to the zombie society. They will regress into mindless monsters and society will crumble. # What system can be put into place in this zombie society in order to prevent loss of human food source? It takes place on Earth in modern-day. Zombies go to work, use cell phones, and even have pets. Let's assume that several years have passed since the zombies defeated the humans. UPDATE: The meat of an infected human becomes inedible when the virus first spreads. This happens even before the first symptoms emerge. This is similar to a cold, where someone is "sick" before they even feel ill. So originally it might not have been uncommon for a human to be killed for meat, only to realize their meat was inedible. Methods of testing a human for the virus beforehand would have been developed to prevent this. However, this would be a major political issue: killing the infected human prevents overpopulation...but if they were infected, they weren't really human. It would become an issue similar to abortion, where the debate involves answering the question "At what point are they considered one of us?" The zombie virus spreads the same way a human cold spreads. So unlike most zombie stories where there is a definitive "Oh, he's gonna turn into a zombie now" moment, it is usually left uncertain. This mean zombies need to be *extra* careful when handling humans. Zombie traits: * Zombies no longer get ill * Heart rate is much less than a human's. (about a fifth of a human's on average) * They can get injured and killed the same way humans do. (except illness) Bleeding out as a zombie still happens, however the slower blood flow means it happens much more slowly. * Looks exactly like a human being. No physical trait differences are visible. --- Things I think I've figured out: * Animals and/or plants are absolutely needed: Humans must be fed and kept alive. * Zombies would very quickly form opposing political groups regarding issues about humanity and how they should be treated. Another thing I'm having trouble with is deciding how the zombie society would change and differ from a regular human society. But that can be a later question. Right now I'm focused on figuring out how to keep the society from crumbling because of a loss of human food sources. [Answer] In such a society, numerous political and ideological measures would appear, just as there are currently numerous views on how to treat, raise, and care for animals (or viruses, or plants....). Your situation has two competing problems: (1) humans can easily become endangered animals, and (2) restricting the deaths of humans is not possible because they're needed for food. For *everyone*. Thus the *growth* of humans would become an item of central concern. ## Artificial Wombs Current technology has [grown lambs](https://www.sciencemag.org/news/2017/04/fluid-filled-biobag-allows-premature-lambs-develop-outside-womb) in [artificial wombs or "biobags"](https://www.theverge.com/2017/4/25/15421734/artificial-womb-fetus-biobag-uterus-lamb-sheep-birth-premie-preterm-infant) which can be seen briefly in [this youtube video](https://www.youtube.com/watch?v=LWpsJIFbdIo). Currently the limitations on human experimentation come down to politics; if humans were suddenly necessary for consumption, those issues would (mostly) go away - at least enough for government approval to begin human experimentation. This process helps to grow humans in sanitary conditions, keeping them away from the zombie virus. ## Lab-grown Meat Stem cells from animals, grown in a lab, into fat and protein. [This video shows lab-grown meat already in work](https://www.youtube.com/watch?v=bjSe-0vSRMY) by different companies in both America and Israel - again, limited only by regulatory issues (in America, the FDA and Dept. of Agriculture). These issues would go away in such a zombie scenario. You can read more on lab-grown meat [here](https://www.cbc.ca/news/technology/what-on-earth-newsletter-lab-grown-meat-green-energy-1.5281252), [here](https://www.scientificamerican.com/article/lab-grown-meat/), and [here](https://newfoodeconomy.org/new-harvest-cell-cultured-meat-lab-meat/). ## Human Farming How we treat animals currently is a topic of large debate. Many vegans cite ethical issues, and others choose to eat meat from only local, ethical farms. There's no reason to think this would be different for humans in a zombie-dominated world. Some zombies would be vicious and force-breed humans, others would try to treat humans more like pets, or even equals (waiting for them to grow old and die before consuming their flesh). ## Regulations There are potentials for government regulations requiring a minimum number humans on reserves, farms, or other locations, as well as safe handling of human flesh and tissue. Just like the modern world, your zombie apocalyptic would would have some countries taking more draconian measures, some more laze-faire, and some more authoritative. [Answer] **Population Control** More zombies means more food needed. The zombies need to keep their numbers down as not to exhaust the food supply. They could wall off the humans into parks and reserves to keep them safe from zombies on the condition once the humans reach the age of sixty, they commit suicide and become zombie food. Dying before being eaten would stop more zombies from being created but still leaves a long and fruitful breeding life. The zombies then ration out the corpses so everyone gets enough to not go mad. [Answer] There is one answer to control large mass of not-so-intelligent beings as humans: **Religion** To take it short humans should be kept in a low cultural (aztec-like) isolated tribes and zombies should live in "cities of gods". Eating for zombies is a holy human sacrifice for tribes. This solves a lot of problems - zombies even do not need to fight for their meat (there would be even overproduction at droughts), or even go to humans. "Sacrifices" would come to them by their own foots. Only some "miracles" as cropdusting or medical and instrument drops are needed. If tribe turns into zombies those "tribe" zombies should be killed: they a usless for high tech zombies as specialists, are not eatable and can "break belief" (last one is a good story plot for this world) [Answer] If I was a zombie I would farm humans. With human meat being a necessity your zombie society would keep people in a sterile environment, with ample food and no means of education. No human would be educated, and they would maybe lose some of their intelligence through selective breeding. the zombies would have to wear airtight suits, so as not to infect the humans. ]
[Question] [ The Apollo-era [A7L Extravehicular Mobility Units](https://en.wikipedia.org/wiki/Apollo/Skylab_A7L) were used for less than eight hours at a time, within a few days, with a maximum of three moonwalks per mission. Assume a fictional moonbase with 1960s-era technology, with some reason to have frequent surface activity. *What are the limits on suit maintenance, and which ones could be overcome easily with a few kilograms more suit weight?* * The PLSS had [silver-zinc batteries](https://en.wikipedia.org/wiki/Silver_zinc_battery), yet I believe that the batteries were exchanged rather than recharged. Are there reasons not to recharge them on Luna? Or am I mixing battery technologies? * The PLSS also had [lithium hydroxide](https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber#Lithium_hydroxide) CO2 scrubbers. Would a regenerative system have been possible at the time? * Could the coolant water have been recovered? * And the one where I'm really stumped, what would regolith do to the fabrics and seals? Could they be dusted off easily, or would a few use cycles start abrasion. * Could the body waste subsystems be laundered? * Were there limits on the shelf life of (unused) spare suits? [Answer] > > The PLSS had silver-zinc batteries, yet I believe that the batteries were exchanged rather than recharged. Are there reasons not to recharge them on Luna? Or am I mixing battery technologies? > > > I'm reasonably certain that these were the non-rechargeable type, and rechargeable variants didn't exist back then. There weren't many rechargeable battery technologies available at all... possible only lead acid (heavy, though that's less on an issue on the moon) and ni-cads, which were a bit rubbish. Your moon base would presumably have to use one of these. You could always use tethers for most work, and a more substantial power source like a fuel cell on a buggy. > > The PLSS also had lithium hydroxide CO2 scrubbers. Would a regenerative system have been possible at the time? > > > Possibly, but the chemistry required to get your lithium hydride back isn't terribly difficult so it could be recycled. This may be simpler than trying to use other rebreather technologies, certain in the era you're considering. > > Could the coolant water have been recovered? > > > Probably, but the coolant system does have a limited lifespan, I do believe. I'm not sure how practical cleaning and refurbishing it is, nor do I know if there was a reasonable alternative available Obviously one was never engineered, because EVAs in earth orbit can get fresh kit easily enough, but that's not to say that it was impossible and maybe some investigation of old-school manned mars mission plans might bear fruit. NASA are [working on a replacement](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130011426.pdf) for the current version of the cooling system for longer term usability. > > And the one where I'm really stumped, what would regolith do to the fabrics and seals? Could they be dusted off easily, or would a few use cycles start abrasion. > > > Moon dust ruins *everything*. Seriously. This stuff might be the thing that renders your moonbase (or mars bases, for that matter) impractical and unsustainable. The stuff is sharp, hard and chemically reactive. It'll abrade fabric and degrade seals and it is toxic to boot. You'll get loads of problems with static. I'll bet it absolutely won't just dust off easily, and even if it does it'll hang around to ruin other things including your health. I think there's some recent research done on ways to overcome this (using double-shell spacesuits, and sintering dust around your base to reduce exposure risks, for example) but I don't know how far back this research went (and I can't find relevant NASA papers right now, but I'm sure they'll pop up soon enough). I seem to recall there was some relevant research back in the day, but I can't seem to find the right search terms for a useful answer. In any case, this is clearly the major issue, as you've already spotted. --- *Edit* dhinson919 kindly supplied a link to [The Effects of Lunar Dust on EVA Systems During the Apollo Missions](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050160460.pdf), over 60 pages of Bad Things and complaints associated with moon dust, including a load of relevant quotes from the astronauts themselves. Particularly relevant: > > > > > > *Pete Conrad’s suit, which was tight before the first EVA, developed a leak rate of 0.15 psi/min after it, and rose to 0.25 psi/min after the second EVA. Since the safety limit was set at 0.30 psi/min, it is doubtful whether a third EVA could have been performed, had it been scheduled.* > > > > > > > > > TL;DR: the stuff got everywhere, it was very hard to remove, attempts to reduce abrasion damage were apparently partially successful but issues with seals remains and only the limited number of EVAs and short duration of the trips made this acceptable. This seems like absolutely the number one issue you're faced with. It isn't at all clear to me how capable 1960s technology was at ameliorating these sorts of issues. --- > > Could the body waste subsystems be laundered? > > > Would you even need them? Just pop back to base and poop on an actual toilet. Luxury undreamed of for the Apollo peeps. [Answer] I have some professional interest in the subject in a general way, not specifically to pressure suits. I'm a nuclear safety analyst. Knowing the reliability of equipment depends, in part, on a long service life with reports of failures, and analysis of the failure mechanism. That is, it needs statistics. The longest anybody spent on the moon was, what, about 3 days? Hard to get meaningful operating experience data from that. At least relating to reliability. This was barely enough to get feedback on how well the things fit and allowed people to work. To get this sort of information you would want to take 50 or so volunteers and put them through their paces until you got the first indications of failure. Not an actual failure, but some indication such as abrasion, leaky seals, loss of temperature control, or some such. Then bring in all 50 and go over their suits carefully and in detail. Then do this a bunch of times. This would allow you to determine the most common failure modes. Then you would modify the suits to fix those modes, and put out 50 more volunteers. And you would repeat this process until you got some acceptable life expectancy from the suits. Say, 2000 hours of use with appropriate maintenance. I don't know if any of the suits were put in storage. I seem to recall they were all custom to the individual astronaut, though I have no citation for that. A few at least are in museums, but not in working order. I also seem to recall that later space missions such as Shuttle and ISS had very different pressure suits, again with no citation. So there may be no data, or very little data, on how long these things lasted if kept on the shelf. Estimating the useful life of stored equipment is a complicated thing, especially absent data. It depends on estimates of life expectancy of individual components in expected storage conditions. But it is very often difficult to predict interactions. Maybe that pliable ring in the air tight joint has plasticizers in it that will out-gas and screw up the fabric of the sleeve. Or corrode the metal in the joint. Or fog the visor on the helmet. Sometimes components have not got life expectancy information, especially if they are very new technology. How long will the batteries in a cell phone last if you let them sit uncharged on a shelf at normal room temperature? That's a tough question. [Answer] With 1960 era technology, you are probably looking at the cutting edge as far as space suits and moon suits are concerned. Rechargeable battery technology was in its infancy, materials science had no previous experience with regolith when designing seals and material for the outer shell, and most of the other issues were being solved essentially from scratch. A few possibilities which were under investigation at the time (presumably for the long term moon base projects and Mars missions being contemplated during the Apollo era) included such things as "hard" suits which were made out of metal rather than fabric. <https://www.popularmechanics.com/space/g2306/nasa-strangest-space-suits/> [![enter image description here](https://i.stack.imgur.com/rdkfS.jpg)](https://i.stack.imgur.com/rdkfS.jpg) *Litton RX-2 1963* [![enter image description here](https://i.stack.imgur.com/2lSZn.jpg)](https://i.stack.imgur.com/2lSZn.jpg) *Grumman hard suit concept 1962* [![enter image description here](https://i.stack.imgur.com/hwH4F.jpg)](https://i.stack.imgur.com/hwH4F.jpg) *AX-5. One of the most modern concepts from 1988* Fuel cell technology was well understood and reliable, future hard suits may have used miniature fuel cells rather than batteries for the main power supply. PEM fuel cells have the added advantage of creating water as the byproduct, so waste water from the fuel cell could possibly be used to top up the cooling system in an integrated design. With more experience, I suspect that any sort of lunar spacesuit might end up being fitted with a disposable overall type outer cover. It would be discarded in the airlock so the astronauts would not bring in regolith or moon dust into the shelter, and a fresh coverall would be fitted before entering the airlock for a moonwalk. The issue with this question is we are essentially looking at the problem from the future (we already have some understanding of the issue). We are also in a very different environment. Engineers in the 1950's and 60's generally had no issues in slapping together prototypes and trying things out for real, rather than today's environment where PowerPoint slides, computer modeling and endless layers of review are needed to get anything done. From a realistic point of view, the next generations of long duration Moon Suits would probably be similar tot he AX series of hard suits, and over the 1970's, as more experience was gained, evolutionary changes would have been made to the internal systems, and upgraded suits or replacement parts would be sent to the Moonbase. The only really major change I could see to what was already being proposed and worked on would be a sacrificial coverall to protect the systems from moon dust. [![enter image description here](https://i.stack.imgur.com/NeCSO.jpg)](https://i.stack.imgur.com/NeCSO.jpg) *Tyvek coverall. A sacrificial coverall would look like this pulled over the spacesuit* ]
[Question] [ This question has its origins in the word "dendraphile" used in a YouTube comment. It was used in an insult used by dwarves towards elves. My chain of thought then was that the dwarves would use plainer language like "tree hugger" and after drinking enough beer the "hugger" would be replaced by cruder word implying sexual intercourse. At that point my inner dwarf was like: "It would be just like Elves! Humpf!" But the thing is having sex with trees **really would fit** Elves. They totally would do it if it was practical as part of some weird ritual about being more in sync with the nature. And with magic very little is impractical. Especially for a race that typically uses millennia on some pretty pointless projects because they have some serious personality issues. Then I got to thinking about the specifics. Sex is basically exchange of DNA. It can happen between species and in some cases even between very different species. Bacteria like to exchange DNA with anything and viruses can ferry DNA between cells. But all examples I know are fairly random and irregular. Despite this starting from and being based on fantasy I'd like a science based explanation of how **regular** and predictable genetic exchange would work. Specifically the consequences. We can leave the mechanics of how it happens to "Elves are weird and have magic". I am just interested on how the plant material would fit into the animal cells and what consequences it might have. And same the other way around. What could the plants give animals and what could animals give plants. Note that despite the fantasy elements the actual question is about the science based part. I'd prefer hard science but honestly the background probably takes this too far outside of what might have been studied so requiring citations might be too much. Still it **is** the hard science part of plant and animal genetics I am interested in. Speculation I can do myself. [Answer] [Our bodies are 1-3% bacteria](https://www.nih.gov/news-events/news-releases/nih-human-microbiome-project-defines-normal-bacterial-makeup-body) by weight. Bacteria is vital for our functioning; killing it off has consequences. All cultures (except our very modern one) have special foods and activities that support our healthy microbiome. The very first time we are colonized with bacteria is [during birth](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340742/). Breastfeeding is also an early source of healthy bacteria. > > Many bacterial sources for the infant derive from the maternal > microbiota. Therefore, beneficial infant colonization is dependent > upon maternal genetics, environmental exposures and diet before and > during pregnancy as well as during breast feeding. For example, > prenatal maternal exposure to farm animals and consumption of raw milk > is associated with decreased atopic disease. > > > Perhaps there is something about trees... The soil around trees is filled with amazing colonies of bacteria and other micro-organisms. Bark too. Leaves. Everything. Imagine a particular species (and/or location) of tree whose microbiome is synergistically connected with that of elves. This may not be a genetic exchange in the same sense we mean that two elves (or two trees) exchange genetic material with each other, but it's still a genetic exchange. Bacteria is vital for humans; you could make these bacteria even more vital for elves. Treef---- ... umm "tree whoopee" could be part of their fertility rites. Imagine rituals at puberty, before marriage/partnering, and during pregnancy. As well as couples hoping to conceive rolling around in the dirt and fallen leaves under the trees. While all my examples are for female elves and genderless trees, we can imagine that male elves would also get in on the action. In part to boost their own microbiome (after all, we humans have to replenish our bacterial stock regularly, with our food) and in solidarity with the women. This would be best done orally. But for pubescent boys and men too who feel a particular action is required, I'm sure you can easily come up with cultural reasons for it. Remember too the origins of the word "culture." While it comes from cultivation of the soil (a task that involves microbiomes of many kinds), it a[lso has a relationship to food cultures](https://grist.org/food/fermentation-is-the-basis-of-culture-a-manifesto-by-sandor-katz/). Cultured foods are those that are fermented, i.e., inoculated with bacteria which is encouraged to grow. Elves and trees, well, it's a special relationship. One necessary for their health and wellbeing. Good for the trees too, as they're protected and cared for and can reproduce with ease, with the help of the elves. [Answer] A single genome is capable of producing a wide range of different phenotypes. As an example, every cell in the human body has basically the same DNA, but depending on what genes are activated you get completely different muscle cells, neurons, white blood cells and many more. This same sort of variation occurs at the organismal level as well. Compare the various castes in ants or termites or the myriad of different forms of some aphids that depend on environment or the extreme divergence between males and females of many species. Most plants also produce radically different phenotypes. Plants often have multigenerational life cycles which alternate between haploid and diploid and which can have radically different phenotypes. You would never guess that a fern’s haploid gametophyte and its diploid sporophyte were the same organism based on their appearance. The point of all of this is that there’s really no reason why a single genome couldn’t encode both a plant and an animal at different stages in its lifecycle. When it wants to make an animal it turns on the animal genes, and to make a plant it turns on the plant genes. Of course, how such an organism would have evolved is difficult to imagine, but if you are willing to explain their origins as magical there is no reason why elves and trees can’t quite literally be the same organism. The specifics of how this would work are up to you. One simple setup would be that when two animal elves mated some of the progeny would be a tree elf and when two trees elves mated sometimes the result would be an animal elf. If you want animal elves mating with tree elves another setup could be that the trees represent male elves and animals represent female elves. So the animals mate with trees and give rise to more trees and more animals. It could be much more complex than this if you’d like, real life cycles are often more complex than just a single circular cycle. Go wild. As a parting note, the Pequeninos of Orson Scott Card’s *Speaker for the Dead* is an example of a similar animal-plant pairing in fiction that you may find interesting. (It's a good book too.) [Answer] I like to answer this kind of question by pointing to examples from Earth which can be used as a springboard for imagination. The first and most obvious are the [kleptoplasts](https://en.wikipedia.org/wiki/Kleptoplasty) such as *[E. Clorotica](https://en.wikipedia.org/wiki/Elysia_chlorotica)* which take in chloroplasts from their food and use them for photosynthesis. Some take in whole plant microorganisms and use them as batteries, *The Matrix*-style. However, some, such as [M Chamaeleon](https://en.wikipedia.org/wiki/Mesodinium_chamaeleon), have an [endosymbiotic](https://en.wikipedia.org/wiki/Endosymbiont) relationship with red and green algae, and can continue to photosynthesize despite having broken down the algal cells. Then there's [horizontal gene transfer](https://en.wikipedia.org/wiki/Horizontal_gene_transfer), which has been found to have happened between kingdoms, such as between [arthropods and trees](https://phys.org/news/2016-04-scientists-document-rare-dna-animals.html). The horizontal gene transfer page has more examples, but no really good ones between plant and animal. And that, so far as I can tell, is where it ends... for nature. But what of *science*? Using [somatic fusion](https://en.wikipedia.org/wiki/Somatic_fusion), you can join together the cells of two different organisms, such as [tobacco and humans](https://science.sciencemag.org/content/193/4251/401)! I put an exclamation mark because *humans!*, but really, it's way less exciting than it sounds as a headline. More interesting, I'd argue: but less exciting. In fact, while it's an interesting challenge to be able to write a paper on, I don't think anyone's found anything useful to do with these yet. There's also genetic manipulation, of course, where genes from plants could be included in an animal, or vice versa. This is done, combining [spinach and pigs](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC404050/)! But again, more interesting and less exciting than the mind's eye might expect. No pigs with floppy leaf-ears or anything. Just a higher proportion of certain fatty acids in their tissues. And what of *fiction*? There are not very may [plant-animal hybrids of antiquity](http://mentalfloss.com/article/78792/4-legendary-plant-animal-hybrids), and in general, they were an attempt to explain the origins of the animals, rather than just makey-uppy monsters like chimeras and such: [![enter image description here](https://i.stack.imgur.com/VQbm6.jpg)](https://i.stack.imgur.com/VQbm6.jpg) Then there are many stories of seeds sprouting within humans, which [has actually happened](http://healthland.time.com/2010/08/13/how-can-a-pea-plant-grow-in-the-lung/), not just once but [multiple times](https://www.telegraph.co.uk/news/health/news/7942128/Cancer-patient-pea-plant-growth-bizarre-things-in-humans.html), though not to the point of growing out of someone: [![enter image description here](https://i.stack.imgur.com/MSgyK.gif)](https://i.stack.imgur.com/MSgyK.gif) So what of *elves*? There are a few ways that elves could do this. They could photosynthesize, but for an animal the size of an elf, it'd grant essentially no useful energy. Chloroplasts might, however, provide good *camouflage*, so might well not be worthless. They might deliberately, as a form of scarification, implant seedlings in their skin, or thread them through body piercings, or insert their roots in body orifices - who knows, they're elves, they're weird. I've heard one apocryphal tale of a gentleman who used seeds to increase certain sensations, only to have them sprout, but cannot find any reliable reference for this. IF you wear clothing filled with loam, and walk around with saplings planted in them, eventually, over the decades, you will become encased in trees. Eventually the constriction might kill you, and you will not wake up one morning. Or after sitting and meditating stationary for enough days, you might find that you can no longer lift them up, as your muscles wasted, they grew heavier, and reached little roots into the surrounding ground. A tree lover might not see this as a bad way to go. ]
[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/141122/edit) I wrote a little short story about a classroom in the distant future, where the world becomes "perfect", and the students are analyzing works of satire from different periods. The teacher uses these works to tell the students that the people of the "old world" all were monsters who endorsed genocide. He and his students believe this because the things that could be criticized are so minuscule that sarcasm has become unnecessary. Could this fundamental lack of understanding of sarcasm and satire come about if it was drilled into people's heads that there was absolutely nothing to criticize? [Answer] **No.** Your "perfect society" is far from one. The teacher makes a factually untrue statement about the people of the old world. The government essentially tries to brainwash people to believe there is nothing to criticize. This is an authoritarian system that is fundamentally delusional about itself and detached from reality. A society acting like this would almost certainly be highly inefficient and corrupt. And people would deal with it with sarcasm and satire. Also, sarcasm and satire are not actually forms of criticism. They are ways to deal with issues that for one reason or another cannot be criticized. A "perfect society" that genuinely had very little real issues would be positively full a satire and sarcasm. I mean, after they installed that weather control system we can't even complain about the weather. And what are we supposed to make fun of if all the politicians are honest and competent? This is the worst government EVER! (Except for all the governments that came before it.) [Answer] > > 'The teacher uses these works to tell the students that the people of > the "old world" all were monsters who endorsed genocide' > > > And exactly how does the teacher do this without being sarcastic of the people from the 'old world'? It seems that the power brokers of this world maintain their grip over society by actually USING sarcasm and satire against the 'opposition' (old world). The issue I have is in the use of the word 'teacher'. Is this person a 'teacher' as in 'guiding the development of intelligence' or an 'indoctrinator' as in 'instilling an ideology'? If the students are not completely brainwashed and intellectually numbed, and the teacher is indeed attempting to promote intellectual discourse instead of wrote learning, I am sure that with enough exposure and experience they would eventually understand that indeed the lesson was entirely sarcastic. If the students are completely brainwashed, as in the 'Fahrenheit 451' meme, this society would be stagnant and terminally so, and the question would be moot. Hopefully, there will be no blue koolaid. [Answer] ## Maybe There are a sizable number of people now who don't understand satire and sarcasm. I have read the number is as high as one in three. In addition culture can greatly influence peoples perceptions. I read an intriguing what if story once based around Shakespeare being exiled to the failed Roanoke colony, taken in by native Americans who viewed Hamlet as a comedy and a Midsummer's Night Dream as a horror story. Kafka viewed his works as hilarious satire. On reading Machiavelli, I wondered if The Prince was in fact satire that no one realized. Every couple of years there is a story about parents complaining about a Modest Proposal being taught not realizing the joke. A whole society not being able to tell satire doesn't seem that far fetched. [Answer] There is no such thing as a "Perfect" society. When one *aspect* of the society becomes "perfect" (by whose standard?), it requires other aspects to become imperfect. For example, if there is no more death, suffering of health or mental diseases, etc, then (a) goodby healthcare profession, insurance, and politics - which destroys the hopes and dreams of many - and (b) no more death = shit ton of people alive across time. Do you implement population control? That's forced oppression against people's desires to have children. Even if everyone "just chose" not to have any more kids, that means a plethora of interesting psychological problems that comes from never having to care for anyone younger than you. We've spent millions of years evolving with the desire (need?) to have children and raise families. What happens to us when we take that away? I'd hardly consider that "perfect". But I wouldn't consider the idea of death "perfect" either. It gets more nuanced than that - an extreme Libertarian might view a "perfect" society as one without a government, while an extreme Communist might view a "perfect" society as one with *only one* government. These are fundamentally incapatible viewpoints. By whose definition of "perfect" is this future world? > > The teacher uses these works to tell the students that the people of the "old world" all were monsters who endorsed genocide > > > and > > ... if it was drilled into people's heads that there was absolutely nothing to criticize? > > > An authoritarian, mind-control system of education is far from "perfect" in my mind. That said, yes, it *is possible* to brainwash people into not understanding sarcasm or satire. It is possible to force people to believe all sorts of horrible things through violent, oppressive use of force and mind-control programs. ]
[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/140324/edit). Closed 4 years ago. [Improve this question](/posts/140324/edit) In my world I have introduced two super powers, and both can be accidentally acquired by an otherwise normal human: one is to see infrared and the other is to see ultraviolet. I am aiming to have that observation describe the Earth of 2019 exactly scientifically correctly. For infrared I am thinking mostly near IR through thermal IR. For ultraviolet I am thinking mostly UVA, UVB, and UVC. ## What sights would stand out to someone who has suddenly developed the ability to perceive in infrared and/or ultraviolet? ### 1. What light sources would stand out as having more or less UV and IR radiation than others, or a dramatic mismatch between one of those and the visible spectrum? e.g. sunlight vs. moonlight, fire, lightning, stars, planets. What other than fire and bodies emit IR? What about UV? That sort of thing. ### 2. What objects would reflect or block or let through UV and IR radiation noticeably more or less? How do he shadows of leaves, look in IR or UV? Do mirrors reflect different parts of the spectrum differently? Do trees? Are some things opaque to UV or IR that are transparent to visible light or vice versa? Etc. *[edit note: I changed this from the hard-science tag to science-based after editing it earlier.]* [Answer] The world will look mostly the same, but there will be some small differences. For example, while you will technically now be able to see UV/IR light from the sun, it will not be noticeable because the sun emits such a broad spectrum of light that any particular additions won't matter. * The color of the sky will be slightly more UV-looking due to Raleigh scattering in the atmosphere. * All screens will be somewhat "off". Right now, color screens are calibrated to look most like the real world to a human eye. However, if we change what the human eye can see, then current screens will not be able to represent it accurately. If you take a picture of something UV/IR-colored, the camera could pick it up depending on the lens filters, but will register as a combination of red, green, and blue light, therefore looking different when viewed on a screen. * Security cameras, remotes, and phones will all flash lights at you. Security cameras have big IR flashlights on them, remotes communicate with IR light, and your iPhone X will flash an IR light in your face every time you unlock it. * Foliage will look different. "Green" plants reflect sunlight in green and infrared wavelengths, so lots of plants will change color. Two plants that were the same color might not be anymore. * Some things will look slightly more tinted, some things will look slightly more visible. Remember, you are not losing the ability to see anything, so a window that blocks UV light (aka all windows) will let the same amount of light as before, but the outside is slightly brighter due to the UV light, so it would appear slightly tinted. On the other hand, some plastics let UV light through but not normal light, so these would appear translucent and UV-colored where they were previously opaque. * Mirrors will appear the same as before. Lenses/glasses *might* give you some chromatic aberration in the UV/IR spectrums that would have gone unnoticed before, but I doubt this will be noticeable. * Unfortunately, stars, planets, and the rest of space will look the same. All the cool astrophotography you see is done with sensitive equipment over long periods of time, picking up way more light than a human could see. At best, it's a tiny bit brighter because of the extra photons you can pick up, but the extra brightness of your environment would cancel it out. EDIT: My answer was actually based on the assumption of near-IR, which behaves pretty much like visible light, and not true infrared where you could “see” heat. With that in mind, I’d have to change a lot of my answers. Yes, you would be able to see people in the dark as they radiate heat. As for everything else, hot stuff would glow kind of like extremely hot metal, except at normal temperatures. Also, there are some metallic surfaces that act as mirrors to infrared/heat, so you’d possibly be able to use them to see things you ordinarily couldn’t. Unfortunately, almost any transparent object blocks heat, so you wouldn’t have any effects looking through glasses or windows. [Answer] The question as asked cannot receive a definitive answer, because how luminous a light source appears depends on the response curve ("[luminosity function](https://en.wikipedia.org/wiki/Luminosity_function)") of the receiver. Normal human eyes do not produce a visual sensation for infrared and ultraviolet, so what the response curve should be depends on the decision by the author. [![Photopic and scotopic luminosity functions of the human eye](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Luminosity.svg/640px-Luminosity.svg.png "Photopic and scotopic luminosity functions of the human eye")](https://commons.wikimedia.org/wiki/File:Luminosity.svg) *Graph of photopic luminosity function of the human eye (black) including CIE 1931 (solid), Judd-Vos modified (dashed), and Sharpe, Stockman, Jagla & Jägle 2005 (dotted); and scotopic luminosity function, CIE 1951 (green). Image by Dicklyon and Innesw, available on Wikimedia under the Creative Commons CC0 1.0 Universal Public Domain Dedication license.* Note: This is why we have special [photometric units of measurement](https://en.wikipedia.org/wiki/Photometry_(optics)#Photometric_quantities) such as candela, lumen and lux and we don't measure light in radiometric units. For example, one candela is 1/683 watt per steradian at 555 nm, but at 690 nm (deep red, near infrared), one candela requires almost one watt per steradian. Nevertheless, some general impressions can be provided based on the vast number of infrared (and, since digital photography, ultraviolet) photographs available since the beginning of photography. (It is actually *hard* to make a photographic sensor with the exact same response curve as the human eye...) [![Backyard garden near Moscow](https://farm3.staticflickr.com/2872/34095665446_2cd1b34ab0_z.jpg "Backyard garden near Moscow")](https://www.flickr.com/photos/sovraskin/34095665446) *Backyard garden near Moscow. Infrared photograph by [sovraskin](https://www.flickr.com/photos/sovraskin/), available on Flickr under the CC BY 2.0 license.* Look at the (pretty typical) infrared photograph of a backyard near Moscow. Note the major dissimilarities with a photograph in the visible spectrum: * Grass and foliage appears very light; this is because leaves reflect as much infrared light as plant physiology can achieve -- infrared light carries heat, and plants don't have a good way of cooling, so they try to avoid absorbing infrared. * The cloud in the sky have a dramatic contrast. Clouds reflect infrared light, so they appear light, whereas clear sky is mostly devoid of infrared, so it appears dark. [![Bobcat at Night](https://farm8.staticflickr.com/7405/11425796503_61ef1a31dd_z.jpg "Bobcat at Night")](https://www.flickr.com/photos/santamonicamtns/11425796503) *Bobcat at night. Infrared photograph captured by a remote camera trap operated by the [American] National Park Service. Photograph in public domain, available on Flickr.* * When taking infrared photographs at night, mammals and birds appear light (sometimes even as light sources), because they are warmer than the environment. Flowers appear dramatically different in ultraviolet; bees and other pollinating insects see ultraviolet light, and flowers are optimized to be attracted to insects and not so much to humans. There is an excellent blog, [Vis-UV-IR Flower Photos](https://vis-uv-ir-flower-photos.blogspot.com) by Dave Kennard, with many photographs of flowers taken once in visible light, once in ultraviolet and once in infrared, with descriptions of the differences. You may also want to read "[Ultraviolet Patterns in Flowers,or Flowers as Viewed by Insects](http://arnoldia.arboretum.harvard.edu/pdf/articles/1982-42-3-ultraviolet-patterns-in-flowers-or-flowers-as-viewed-by-insects.pdf). [![Mimulus flower in visible light (left) and ultraviolet light (right)](https://upload.wikimedia.org/wikipedia/commons/6/6b/Mimulus_nectar_guide_UV_VIS.jpg "Mimulus flower in visible light (left) and ultraviolet light (right)")](https://commons.wikimedia.org/wiki/File:Mimulus_nectar_guide_UV_VIS.jpg) *Images of a Mimulus flower in visible light (left) and ultraviolet light (right) showing a dark [nectar guide](https://en.wikipedia.org/wiki/Nectar_guide) that is visible to bees but not to humans. Photograph by Plantsurfer, available on Wikimedia under the CC BY-SA 2.0 UK: England & Wales license.* [Answer] One thing I know about is **flowers**. [Bees can perceive UV](https://www.beeculture.com/bees-see-matters/). The flower has the regular colors we see, but much more: The UV light shows many stripes on numerous species of flowers. Those stripes guide the bee to the source of pollen and nectar. The location is the optimal one for cross-pollination, limiting self-pollination as much as possible. There are some Youtube videos as well. [Answer] I do a lot of work with thermal imaging, and scenes through IR can be completely different to how they appear in the visible range. All objects with temperature emit thermal radiation according to the [Planck function](https://en.wikipedia.org/wiki/Planck%27s_law). The IR range is generally broken up in to 3 wavelengths (as far as people using thermal imagers are concerned)- * Long wavelength IR (~8-13 microns) * Medium wavelength IR (3-5 microns) * Short wavelegnth IR (~1 micron) You also have near and far infrared either side. You'll notice that there are gaps between medium and long, for example- this is because the transmission of IR through air varies substantially. How the person experiences the world through IR would massively depend on the wavelength range they are sensitive to. [![Infrared transmission spectrum](https://i.stack.imgur.com/R2J4P.jpg)](https://i.stack.imgur.com/R2J4P.jpg) If you use a thermal imager in a room without any particularly hot objects in it, the entire room will seem uniform- you're pretty much unable to see the outlines of objects when they are the same temperature as the room so you can be 'blind' in many cases. Some interesting things that you can pick up in IR that you wouldn't be able to pick up otherwise is things like handprints on objects (just placing your hand on a table for a second or so causes enough of a temperture change that it is clearly visible for the next few seconds in IR). Looking at hot objects (~700 degrees for example) would likely be very painful for the person, and depending on the sensitivity of their eyes to IR could potentially blind them. Picking out certain objects would be very easy for the person, like a person in foliage. In addition, just because a material is transparent in visible, doesn't mean it would be in IR- glass and water, for example, strongly absorb many of the useful IR bands. This means that wearing glasses (unless they are made of something like germanium or quartz) would invalidate their ability to see IR. The sky at night would appear to be pretty much completely uniform, like rooms. During the day even looking at the sun could potentially blind the person (though then again, that's the same for everyone). Potentially, they could see people who are unwell with IR (many illnesses present with fevers, increasing skin temperature). One property materials that is of particular importance when you're talking about infrared is [emissivity](http://www.npl.co.uk/reference/faqs/what-is-emissivity-and-why-is-it-important-(faq-thermal))- essentially it's how well a material emits (or reflects) thermal radiation. An object with an emissivity of 1 emits the maximum amount of radiation possible according to the Planck function given its temperature, and reflects none- conversely, an object with an emissivity of 0 that is non-transparent will emit no thermal radiation, and will be a perfect mirror. (Side note- emissivity also depends on wavelength, temperature and direction). Polished metal and graphite, when at the same temperature, would be visibly different due to the amount of radiation it emits. [Answer] One way we currently view infrared radiation is through the use [Forward-looking infrared (FLIR) cameras](https://en.m.wikipedia.org/wiki/Forward-looking_infrared). > > Which use detection of infrared radiation, typically emitted from a > heat source (thermal radiation), to create an image assembled for > video output. > > > You should be able to find many images and videos that illustrate how different things in our world look in terms of their IR-radiation ]
[Question] [ Once the technology is ready to reach and set up a base in Mars (perhaps 10 years if SpaceX expectations come true) could it be possible to build a route among the asteroids to reach Jupiter's moons? The problem of the time of the travel would be more or less the same if you would have bases in the following places, and if you start the travel when the planets/asteroids are closer, > > * Earth - Mars 0.52 AU > * Mars - Vesta 0.63 AU > * Vesta - Sylvia 0.64 AU > * Sylvia - 588 Achilles 0.67 AU > * 588 Achiles - Jupiter 0.57 AU > > > But how about the problems of setting permanent bases in those asteroids, even when some are large ones of almost of the size of a dwarf planet, would it be feasible? Setting up a base in Mars it has to be easier. I suppose they plan to obtain water from Mars, may be they would find a way to obtain Oxigen from the CO2 in the atmosphere, also I suppose Mars is warmer than those asteroids and have more protection (even though a tiny not enough protection) from radiation than atmosphereless asteroids, and how about energy supply, if the way they plan to obtain energy in Mars is somehow related with the sun (solar energy), that has to be harder when you are far away. Could a route among the asteroids be built to reach Jupiter's moons once the technology to reach and set up a base in Mars is ready? [Answer] # Think Delta-V, not Distance It makes *absolutely* no sense to stop at a base on the way. What matters is the fuel/reaction mass to get into a transfer orbit, and to leave it again. The time spent coasting in between is *relatively* cheap by comparison. Sure, you might be able to tank a couple tons of oxygen for your life support, but what if you need to expend *hundreds* of tons of fuel to do that? Nothing gained! [Answer] According to SpaceX, the answer is yes. The SpaceX program is banking on the idea that people can derive rocket fuel from the elements on Mars almost as easily as we can engineer it here on Earth, and water/food/oxygen could be readily processed in bulk, even if it's not as easy when you don't have a livable atmosphere. If this proves to be true, then Mars would become a much better base of operation for solar exploration and habitation than Earth because the lower gravity would allow us to launch large payloads into space VS Earth which is so big that it is near the limit of how large a planet can be an still reach space with chemical fuel. [Answer] You are clearly aware of the fact that a route would not be constant - everything orbits with different periods, and although the asteroids have orbits that are 'close' to one another, they still cover a huge range. Perturbations make life even more complicated. Jupiter and Mars have wildly different orbital periods from one another, of course. The presents a difficulty with setting up staging posts in the asteroids. Even if you always head from Mars to Jupiter around conjunction (the optimal launch window does not precisely coincide with conjunction), the asteroids that will be "on the way" will vary. So you would need a lot of such posts scattered around the belt, and you'd have to be careful in selecting larger bodies such that they wouldn't sometimes cluster all together. It would also be expensive to build and equip these points, and keep them supplied. Even if they were unmanned, the whole point of them would be to hold supplies for such journeys. What is there to be gained from such expense? Is there any advantage to shipping supplies out there to be picked up by people *en route*? If you shipped them in unmanned shipments, they could be shipped more cheaply, but then it would be a challenge to get them *into* a depot at the staging post. However, even if supply caches are desired, they don't have to be in the asteroids themselves. We don't need to *build* a route through the asteroid belt - it's nowhere near as hard to navigate as sci-fi shows like to depict. The distance between them averages as 2.5 times the distance between Earth and the Moon. If we need supply caches put part way along the journey by unmanned flights, we may as well just have containers that fly themselves out there and then do a burn to put themselves in a stable solar orbit, or grapple on to an asteroid if you prefer, to be picked up later. Permanent or semi-permanent installations would simply be unnecessary. [Answer] You could, but not a permanent set of bases. Instead, you would need to have some form of mobile, anchorable bases that hopped from asteroid to asteroid as the asteroid they were anchored to fell farther and farther behind the optimal location for a Mars-Asteroid X orbit. Each of the intermediate stages would need to move on independent schedules, since the outermost asteroids take longer than the innermost ones. The orbital period of asteroids in the asteroid belt runs from three to six years, give or take a bit. Mars has an orbital period of about 1.88 years, so Mars would orbit the Sun 3+ times before the outermost asteroids orbited the Sun once. Unless the bases moved on the basis of an ion drive (spewing out asteroid atoms as propellant), solar sails, or some equally low energy, low thrust option, it is unlikely that anything even semi-permanent could be set up to make the flight in hops. It could be possible for limited, exploratory missions to the moons of Jupiter, but except for being the first man to walk on 10 or 20 moons, why? Well, I can actually think of one possible reason why. The closer you are to the planet, the faster you can control a Jupiter probe. With delays of a second or two (assuming you can safely get that close), you could actually hope to control and direct a flying probe (with the assistance of a lot of AI flight tech) and direct it to interesting features. Except for this possibility (and the possibility of moon probes directed similarly), sending humans out there without a specific target that actually needs human adaptability / flexibility seems a bit foolhardy. ]
[Question] [ In a 'verse with Conveniant Interstellar Travel (in the scale of a few weeks to a few months for neighbouring star systems), the East Orion Company controls large swathes of the sector thanks to their private marines. These marines fight in formation just like they did during the age of Colonialism and Napoleon, except with Near-Future technology. Strategy and Tactics depend heavily on the technology available to the military, this the question is: What technological pressures are required to cause optimum military strategy/tactics to emulate those of 1800s Napoleonic era warfare? [Answer] There's a famous speech by Barack Obama where during his election campaign for his second term where he was accused of neglecting the military. The accusation was leveled against him that the American Navy had fewer ships than it had at the beginning of WWII. His counter to that was that the army also had fewer horses and bayonettes than it did at the turn of the century; because that's not how wars were fought anymore. The point being for your question is that your East Orion Company isn't the East India Company, and isn't going to mobilise troops and fight battles the way they did because the environment in which they fight, and the public rationalisation of those fights, is going to be radically different. If you want proof of that, just take a look at how [drones have changed military tactics](https://www.smithsonianmag.com/history/how-the-predator-drone-changed-the-character-of-war-3794671/). The point is, whenever you have a change in military technology, you have a subsequent change in military tactics and strategy because most technologies are developed to counteract a known weakness in current tactics or strategy. War is increasingly fought with equipment rather than personnel and it is important to note that this will increasingly be the case, especially in scenarios where the people directing the equipment are separated from harm to the equipment. People are expensive to train, and as a result, less and less expendable. A human being who makes a mistake on the battlefield and dies is an incredibly inefficient way to prosecute a war, especially if that human being can learn from that mistake and become a better soldier. This is in effect what happens with drone pilots, who can learn in real time combat situations, take advantage of the semi-autonomy of the drones, and when things go pear shaped with the drone can hit auto-destruct and start again with superior experience. This has happened many times in history. The short-sword in the Roman Army The Bow The Cannon The Musket The list goes on It's not inconceivable that the next big thing in military technology will be focused EMP strikes against drones and other military hardware. That is the next most obvious weakness of modern military strategy, and is likely in turn to be countered with either a counter EMP technology, electronics hardening, or some other counter which renders the EMP irrelevant without going back to the bad old days of risking human lives. If we could accurately predict what that counter looks like, we'd already be developing it. In any event, the military tactics of an FTL capable technology won't involve putting a large number of humans at risk; in all likelihood, it'll involve a deployment ship of a massive number of military drones, and a hardened command and control ship of operators which drive them on the planetary surface. Ironically enough, it may well look like a more adult version of Ender's Game by Orson Scott Card. [Answer] "What technological pressures are required to cause optimum military strategy/tactics to emulate those of 1800s Napoleonic era warfare?" AKA what tech is required to not make people want to hide when being shot at? The first answer that comes to mind is super effective personal shields. Why hide when the enemy can't hurt you? What you need is something like the [Holtzman shields](https://en.wikipedia.org/wiki/Holtzman_effect) from Dune. The Holtzman shield blocks fast moving projectiles but allows slow objects through. Your troops can stay in formation and fire upon unshielded units in safety whilst ignoring return fire but against other shielded troops, you set bayonets and fight hand to hand. [Answer] It´s quite simple. All you need to do is negate technology with more advanced technology. **Make your marines very resilient.** 1. Equip them with energy shields, body armour, gas mask, etc. 2. Equip them with guns with low rate of fire. Something like laser rifle which needs to be charged after every shot. Now you have marines that can survive in close formations and reason for them to fight as line infantry. **Make wireless communication complicated.** Energy shields can also interfere with wireless communication, which opens possibilities for flag signals, motorcycle couriers, messenger pigeons, etc. [Answer] Those tactics really ceased to be efficient when the germans started using the blitzkrieg tactic of bombers, then tanks, then infantry. I believe the napoleonic way had also been diminishing in efficiency due to ever better artillery before that. Make it so that aircrafts are too easy to destroy while in air: better ground-to-air missiles, perhaps launched with simple handheld devices. Make tanks a liability, maybe by having EMP strikes being a thing and cheap (this could also kill drones). Then the military will be forced onto using the old ways again. [Answer] **The weaponry is near future, but is functionally equivalent to that of Napoleon's time.** East Orion has a stranglehold on trade and suppresses indigenous industrial capability to keep the colonies dependent on trade. Both as a byproduct of this lack of industry and as an intentional policy choice, the colonies are without the advanced weapons technology that is possible (and is used elsewhere, in areas not controlled by East Orion). Thus although the tech is by definition near future, the destructive capabilities of the weapons are functionally equivalent to those of Napoleon. The space marines are in large part recruited from native populations and so are not entirely trusted. Also there is always the possibility space marines and their materiel might be captured and their weapons used by the colonists or worse, copied. Thus the marines are sent to battle with weapons of the same destructive capabilities of the colonials they fight. The marines win not because of their weapons, but because of their training and discipline. The lack of advanced weaponry does not mean that the colonists do not use other types of advanced tech. Medical tech is advanced which means most combatants will survive battles. The rationale of Orion: the colonies and the colonists themselves are investments. War is human and from time to time the colonists will need to make war. The space marines might even let them have some victories. It is psychology. But ultimately minimizing destruction of property and exports, and minimizing loss of life means maximizing income on investment. [Answer] As many people have noted in their answers, the battle tactics of an era depends a great deal on the technology available. It is difficult to imagine that any sort of space empire will not be able to field equipment comparable with what a modern 21rst century soldier is equipped with, except perhaps much lighter, more reliable and more lethal. [![enter image description here](https://i.stack.imgur.com/RaXDt.jpg)](https://i.stack.imgur.com/RaXDt.jpg) *Little Green Men. Because it is a space fantasy, right?* So the issue needs to be how to eliminate all these technological advantages, and in such a way that it does not negate everything else. In Joe Haldeman's novel "[Forever War](https://www.amazon.ca/Forever-War-Joe-Haldeman/dp/0312536631)", a soldier in an interstellar war discovers on returning from a mission that due to time dilation, centuries of R&D have happened in his absence and a "Stasis Field" has been developed, which slows the movement of every sort of particle to some arbitrarily slow speed. Electronics no longer work, engines and computers seize up and even biological processes stop. In the novel, covering your spacesuit or powered battle armour in a special protective coating protects you from the effects of the Stasis field, but if someone wants to come in and fight (assuming they are protected as well), then only edged weapons like swords and spears will work.... So the Stasis field is a bit extreme for what you want to do, but there are currently understood technologies which, if developed to extremes, could have the same practical effects on the battlefield. Highly focused EMP weapons could be used to burn out electronics on all but the most heavily shielded devices. Highly advanced cyber warfare weapons would reduce targeting computers, software radios and other computerized devices into junk (or untrustworthy devices with trojan horses and logic bombs implanted that could go off at critical times). The orbiting starships could ensure that no air or enemy spacecraft of lesser size and power than the starship itself could operate over the battlespace.This also applies to military vehicles large enough to be observed from orbit. Now soldiers would be limited to communicating by voice, and advanced weapons systems of all sorts would be ineffective. To reduce weaponry to muskets and bayonets, there would need to be some sort of way of disabling modern explosives. Perhaps the battlespace was seeded with some form of nanobot plague designed to "eat" or neutralize modern explosives (perhaps initially a means of neutralizing IED's), but now gone rogue and mutated. However, traditional black powder isn't to its taste, so black powder weapons have made a comeback. There are a few things which even this scenario isn't going to change. Modern machining means that the muskets can be built to exacting tolerances and rifled, meaning they will be deadly accurate to much longer ranges. The idea of cartridges isn't going away, they are far too convenient as well. So you would actually be looking not at the Napoleonic wars, but the period between the American Civil War and the introduction of automatic weapons in the 1880's 1890's (not volley fire or hand crank weapons like the Gatling or Nordenfelt gun, but true machine guns). So there will be a much greater use of open order and dispersed tactics in order to prevent forces from being gunned down. [![enter image description here](https://i.stack.imgur.com/w191q.jpg)](https://i.stack.imgur.com/w191q.jpg) *10 barrel Nordenfelt gun* Artillery will see the same dynamic, modern machining means there is no need for muzzle loading cannon and rifled breach loaders are far more accurate and dangerous. Firing tables printed in books or mechanical calculators will also be used to rapidly calculate ranges and make artillery a very potent arm. [![enter image description here](https://i.stack.imgur.com/RVy7P.jpg)](https://i.stack.imgur.com/RVy7P.jpg) *Canon de 75 modèle 1897. That is just going to wreak your entire day* So assuming the technological means to negate communications, electronic and computerized weapons and devices, and some means of negating modern explosives (and indeed many chemical weapons), then you will be thrown back into the 1800's. However, because it is still possible to manufacture weapons using modern materials and techniques, you will be in the mid to late 1800's in terms of technology, and your solders will be fighting in the manner of the American Civl War or the Franco-Prussian war. [Answer] **Communication and Intelligence blackout technology combined with armour to allow only low accuracy weapons** The dominance of the 'column' and 'line' formations were a result of the ability to keep troop cohesion together, enable force movements over fields which were coordinated and powerful. Another of the main issues during the Napoleonic era was communication. Not having radios meant armies needed to be organised into larger groups, with strict formations to manoeuvre them on the field. Also, the inaccuracy of muskets meant line attack formations were the only way to project force, as individual fire was largely ineffective. Slow reload times also meant units needed strict protocols and command. Napoleonic tactics were also quite expensive, retaining and equipping a large army. They needed many soldiers to accomplish objectives, and a very hierarchal command structure. The advent of regularly made rifles (which were more accurate) and insurgent warfare where force can be equally (if not more) effective without such coordination meant these tactics gave way to more entrenched forms of warfare and more independent units. Automatic fire also meant exposure became an issue, exemplified in WW1 where trenches were the norm and even bright uniforms presented you as too much of a target. To return to this era you need to accomplish a few things: * The elimination of Space, and Air power * The lowering of accuracy of small arms and slower reload times * The removal of communication between units, except that which can be communicated on foot or by horse * The reduction of Force Multipliers to make people required to enlist (ie. lessening of value of a person to be essentially only a drone carrying a small firearm), and removal of economic impediments to using large amounts of personnel. * Adjustment of Officer to Enlisted men ratio (proportion of officers in a military is now much higher than in the Napoleonic era) * Elimination of any mechanised units such as tanks or APCs, and long range artillery. I imagine that if there was jamming technology to eliminate all forms of satellite, radio and other communication, combined with personal armour protection capable of withstanding being hit by a round, with only firearms that could penetrate again being small, non-automatic and manually reloaded would contribute to this. Combined with Air and Space power being ineffective by perhaps AI-controlled advanced laser technology, including artillery shells, and no power sources available for mechanised units, and also an excess of available personnel, combined with a limited value of human life, via perhaps a strict class system with a low proportion of officers (perhaps obtaining officer commissions through nobility and connection) and a large amount of enlisted men. This could achieve what you are looking for, but again a feature of such battles were the incredible loss of human life and a strict class and command system. [Answer] Short answer: none. Long answer: absolutely none. Linear battle tactics were on their way out decades before what we'd consider advanced modern warfare technology was on the scene. Once you had accurate, long-range rifle fire (even single shot) and quick-firing artillery with explosive shells fused for airbursts, the official name for linear formations on the battlefield changed to "target". Possibly "abbatoir". Cartridges and rapid-firing automatic weapons from the Gatling on up was simply the icing on the cake. World War One demonstrated the utter futility of trying such tactics, and that's where they were running as fast as they could toward enemy lines to reduce the time they'd be in the line of fire, rather than advancing and firing in ranks. They'd be dead before they finished assembling if they'd tried that. That style of warfare was dropped by various German states and the Russians in the 1860s in exchange for skirmish-style warfare. The French and German Empire officially gave up linear tactics after the Franco-Prussian War (1870-1871) when it was clear the tactics were totally obsolescent. The British Empire (not being involved in a major war against similarly-armed opponents) waited until the Boer War to officially toss it in the scrap-heap. ]
[Question] [ I have a tidally locked planet on a circular orbit, with an axial tilt of 22.5° That means one side is always in the sun, the other one in the shade. The subsolar point moves along a north-south line during each rotation around the sun, 22.5° each way. The night side can see the stars. How would someone on this planet determine their position? Both on the night and the day side? What tools would be necessary? Sextant, some sort of table of celestial positions, a time-keeping device? How precise would it have to be? Many thanks, I am looking forward to your comments and answers! [Answer] If the person is wandering across the broiling wastes of the sunward side, then a [gyrocompass](https://en.wikipedia.org/wiki/Gyrocompass) (since there's probably no magnetic pole anymore) is needed to determine a north-south line, and a simple stick-and-shadow sundial can be used with that north-south line to [gauge both latitude and longitude](http://www.open.edu/openlearn/society/politics-policy-people/geography/diy-measuring-latitude-and-longitude). No need for a reliable clock, since the sun is always in a constant, predictable position. If the person is wandering across the frozen wastes of the night side, then the traveler will need the gyrocompass and a small ephemeris with key equatorial star positions to use in place of the sun, and a sextant to use in place of the stick. A reliable calendar (not clock) is needed here, since the star positions do not change significantly each hour. If the person is wandering along the terminator, then they already know their longitude, and can use the sun-glow or a sextant-with-equatorial-star to calculate latitude. A simple square-and-protractor to measure the angles would be handy, as most folks aren't very good at estimating angles by eye. Of course, since the traveler is likely to have space travel (how else did they get there?), they could simply have a GPS satellite constellation in orbit, which makes the answer much easier. [Answer] If it's tidally locked to the sun, by definition there's no such thing as axial tilt. That can be disregarded. The first thing is to not think of latitude and longitude in the way it's oriented on Earth. For simplicity, we'll assume the same numbering system as on Earth (360 degrees = full circle), and for timekeeping, we'll assume one orbit around the sun is 100 days (Earth standard). The center of your navigational grid on the lit side is going to be the sun. Directly overhead marks the zero position, the hot pole. Instead of 90 degrees, it's going to be labelled 0. The terminator--ignoring atmospheric diffraction of light--is going to be 90. That's going to be your latitude. On the daylight side, easy to find; you simply use a sextant to measure the height of the sun over the horizon, and better than the Earth, you don't have to wait until midday to do it; you can do it at any time. On the cold side, you rotate the grid. Now, your reference is a recognizable star or constellation closest to your planet's orbital axis, so it's the closest thing to unmoving you can find in the sky. Essentially, instead of finding a pole star for your planet's rotation as on Earth, you find it for your planet's revolution around the sun. Find one above and below the orbital plane, and you've got a way of determining stellar latitude by measuring the distance of one (or other features, as the sky is mapped) above the horizon. Picture it this way: Imagine that on the Eurasian side of the Earth, latitude and longitude are exactly like they are now, but on the side with the Americas, it's turned sideways so that the "pole" is centered on the Galapagos islands. Now 90 degrees *latitude*, as centered on the Galapagos, would be the same great circle around the planet as 0/180 degrees *longitude* based on the Eurasian Grid. The Eurasian side is the dark side of the planet, the Galapagos side the light side. Okay, so on the Eurasian night side, further measurement is relatively easy, once you've invented reasonably accurate timekeeping mechanism (ie, clocks). You've got astro-north, and astro-south. You know that stars near the astro-equator (which would be the plane of the planet's orbit) take a half-year (50 days) to go from horizon to horizon. At day 1, it rises above the horizon, is at its apex at day 25, and set on day 50. If you have accurate timekeeping, you know that at a specified location at a given date a given star should be a certain number of degrees above the horizon. If you measure the height, you can measure the difference between where it is and where it should be on a given date as seen from your latitude, and that can be used to calculate the longitude. Now, this only works if you have accurate timekeeping devices so you know your date/time compared to the reference point, but really, not a lot of difference from the problem of measuring longitude on Earth before the advent of accurate portable clocks. On the day side, it's trickier. Solar latitude is trivial to determine, as mentioned. Solar longitude becomes harder without the stars. You're initial assumption (with the sun "bobbing" up and down, as seen from the planet) would make it easier, but that can't happen if the planet is tidally locked. [Answer] With a south pointing chariot <https://en.wikipedia.org/wiki/South-pointing_chariot> This Chinese invention is a chariot with a pointer linked to the wheels with a clever mechanism. It would point in the same direction no matter which way you turned it. The Wikipedia article says that it was probably not used for navigation and was really just a curiosity. The Chinese also invented the magnetic compass for one thing. The main issue with it is the impossible amount of precision that would be needed to make it work over long distances. If you can manufacture it to a level of precision that is almost unheard of even today, run it on perfectly level ground, suffer no wear on the wheels whatsoever and if you happen to live on a world that is flat, it works quite well. Otherwise, not so good. That said, it also mentions that if you are traveling on long, straight roads, you could disconnect the pointer, and when you get to the end of the road you can carefully line up the chariot with the road, connect the pointer, turn onto the next really straight road, line up your chariot again and disconnect the pointer. This greatly reduces mechanical error, although at some cost of handling error, also at the cost of making every road the Roman way. ]
[Question] [ A secret enclave of sorts wants to survive a nuclear war, which they know is inevitable. They plan on riding out the apocalypse on an oil rig, 175 miles off the California coast out in the Pacific. They build an oil platform, the size of the largest oil rig today, disguising it as a commercial project. They will need to stay on their little oil rig for at least 150 years with 2,500 people living there, and they have to maintain a modern style of life. What modifications would be needed to make for these criteria? [Answer] **Eat the oil**. The Deepwater Horizon was a big oil rig and it had a crew of 130. You have 20 times that many people living on your rig. There is no way to store enough food for 150 years. You cannot support that many people by fishing the area. You will need food but you have nowhere to grow it - every square foot of horizontal space on your rig is full of people. Maybe you could roll out floating farms - aquaculture. It is conceivable with the right crops. But here is the SF idea that is so weird it could save what seems like an unworkable premise. You are on an oil rig. Pump oil. Through the Fischer–Tropsch process you can process petroleum into edible calories. <https://www.sciencehistory.org/distillations/magazine/brave-new-butter> You can make plastic out of petroleum and use that for things like clothes that will wear out with the generations. Solar, schmolar - run diesel electric generators and a diesel mechanical desalinator. [Answer] There is another question in the site, in which the OP asked: [Where on Earth is best to build a large underwater lab complex?](https://worldbuilding.stackexchange.com/q/100837/21222) > > One of the obvious ideas for the location of a large laboratory would be underwater, where you don't have to hide it under some alternative identity to keep people away and there are far fewer rules and regulations to deal with outside of the ones you set yourself. So, assuming I have the resources to build such a place, where would be my best options to construct it if I want to take advantage of as many natural resources as possible? > > > [My answer there](https://worldbuilding.stackexchange.com/a/100846/21222) contains some parts which could be reused here, with some modifications. About being secretive: > > It is exactly because you don't have a cover up that you will get prying eyes. What do your goons tell the dock officers when they get asked about the destination for all those tons of fertilizer? > > > Instead, find or found some legitimate business that can only be conducted very far from the shore, and then you can buy all the supplies you need with practically no questions asked. > > > If you do wish to live strictly in an oil field, you won't have the resources to feed everyone just off of it. But you can trade with unsuspecting nations: > > For example, pair your lab up with an oil company. You can build the lab right under an oil platform. The platform provides the fuel, energy, and the facade you need to buy all kinds of tools, chemicals, machinery and other supplies. If you happen to own the platform you can also use its profits to bankroll the lab. Otherwise the lab provides tech and food (for those courageous enough to eat... whatever it is that you do there). > > > You could get some more resources in an autonomous way if your rig is close to an island: > > If you want to go green for whatever reasons, you could find a university that does state-of-the-art technological research (MIT, Caltech) and conduct research on wave power. This way you get paid to build your own generators instead of having to spend your own money on them. Find some Central or South America island to conduct your research - you can use the excuse that you get more solar power that way, also altruistically you are going to help some poor country with their economy... And then you use the local corruption on your favor, to keep prying eyes away. Bonus if the island happens to be a fiscal haven. Honour the research contracts with your partners, but do keep a couple offices and rooms in the underwater facilities which only a select few mad scientists have the clearance to visit. > > > If the island is owned by you, either *de jure* or *de facto*, it would be even easier. And you can let only the most higher ups live in the rig - the lower citizens would be working on arable land. They might not even know about the whold secret society thing. And if you don't mind cold weather: > > Those still too social for you? Partner with a government and help them build a research station on the south pole. Guaranteed supply deliveries, paid by taxpayer money. Just spend a few thousand dollars building a cute house and drilling ice every few months, write something about gas concentrations on different layers of ice... And they will leave you alone to spend the remaining millions on whatever. Build yourself a nice facility inside Lake Vostok, where not even the most powerful spy sattelites will catch you. Have fun! > > > In all options above, someone will bankroll you. You can spend the money in supplies to last for decades. The last option saves you a lot in terms of refrigerators, and your stored food, alcohol and drugs would last much longer. [Answer] They need to import soil to grow food, scavenge several other platforms for spare parts and hope really really hard nothing vital breaks. Oil rigs are not built to las hundreds of years. Then shoot 2/3rds of the people because platforms cannot support more than few hundred people, they just don't have the desalination capabilities or space for quarters or sanitation. even using every surface for farming and fishing It is highly unlikely they could produce enough food for that many people, and of course they can't do this because on an oil platform 2500 people it will be close to standing room only. Your best bet might to use the platform as the core for a large flotilla, storms will reek havoc on such a construct however. Honestly you are just trying to cram too many people on the rig for it to be feasible. [Answer] To do it, the platform would have to be like an iceberg with the platform above the water being a tiny part and a massive underwater base is the rest. The most important thing is power. If you have enough energy, you can run desalination and hydroponics. Stores and supplies don't need to be stored inside the base but could inside sealed containers sitting on the sea floor outside the base The platform above might look like an old oil platform but actually is an armed fortress with hidden weapon platforms. If you actually want to drill for fossil fuels, generators burning natural gas could supply all the power you need. A platform like this would require a lot of planning and some very rich backers ]