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[Question] [ I have a character that achieves an ability similar to scattering and reforming or elemental swarming by controlling millimetre sized surveillance drones to morph into different shapes or disperse back into a swarm. The drones will use a flapping winged method to fly similar to insects. Is there any way I can make them silent or quieter? As I would prefer the swarm to seem more like magic or a super power rather than having a loud buzz when they are together. [Answer] Electrostatic propulsion drone. <https://www.theguardian.com/science/2018/nov/21/first-ever-plane-with-no-moving-parts-takes-flight> > > The first ever “solid state” plane, with no moving parts in its > propulsion system, has successfully flown for a distance of 60 metres, > proving that heavier-than-air flight is possible without jets or > propellers. The flight represents a breakthrough in “ionic wind” > technology, which uses a powerful electric field to generate charged > nitrogen ions, which are then expelled from the back of the aircraft, > generating thrust. > > > Like the described planes, these tiny drones generate charge across their bodies, producing thrust by the whisper silent ionic wind. If one is near you, and you are quiet, you might just barely hear the whisper. It is whispering "cowlinator…. An upvote if you please...." [Answer] Your little drones are 2 rotors, spinning in opposite directions. The net spin of the two rotors cancels out. The rotors are not flush against each other and can tilt slightly allowing directional control. Lift is controlled by the angle of the blades within each rotor. The spin is very fast, very quiet and constant. They never stop spinning. --- [![image added](https://i.stack.imgur.com/BaqAy.jpg)](https://i.stack.imgur.com/BaqAy.jpg) [Answer] The frequency of sound from flapping wings depends on their size. Think of the flapping of a pigeon versus the buzz of a bee and the even higher whine of the mosquito. Make your drones small enough, and the sound will be too high-pitched for human ears. Or, if you want a wild-science twist, arrange them so the sound waves from each drone are cancelled out by the sound from its neighbor, in a mobile version of noise-canceling headphones. Here are other ways of reducing drone noise but those should do :) ]
[Question] [ Dragons are very territorial apex predators. They build lairs on mountaintops, roost whenever they aren't hunting, and they hunt from the sky. With their size, wings and firebreath, there is no virtually no prey that they can't take down. They hunt over grasslands, coasts, and mountain ranges - typically targeting large animals like bison, elk, deer, bears, walruses etc. For their prey, the only way to avoid a dragon is to run for cover and hope it doesn't spot you. For that reason, heavily forested areas make for poor hunting ground. A dragons hunting territory is the minimum ecological area that contains enough prey to safely sustain the dragons bulk. A dragon cannot leave it's own territory without infringing on that of another dragons. Hunting territories are well defined, and fiercely protected. I'm thinking that dragons would have to be sparsely concentrated over a continent, or else they'd destroy the ecosystem by overhunting. With their wings, their territory can be as far as they can fly, and can include land and sea. I'm wondering what sort of size in square miles their territory would actually be, and how many dragons could fit on a map. Obviously it would vary depending on the terrain and abundancy of local prey, but I'm just after a standard ballpark figure. Assume a fully-grown dragon has a 45 foot wingspan, and weighs around 2500lb. Edit: I don't have any information on a dragon's food consumption or energy requirements, but I was hoping for an answer that makes reasonable estimations / best guesses. Assume the dragon is like a dinosaur, perhaps; it's reptilian, but warm-blooded and sustains a large mass. Like any animal, it tries to conserve energy wherever possible and it tries to hunt using the minimum amount of effort. There is some magic involved for it's fire breath / flight, yet assume any magic is secondary and that it still needs to eat like any other animal. [Answer] ## 40-1000 sqkm per animal This depends more on the quality of environment than the animal. Animals change their territory size [drastically](https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2656.12366%4010.1111/%28ISSN%291365-2656.MovementEcology) depending on how productive the environment. this is actually a far better predictor of territory size than the animal size. there are two ways to go about this, the easiest is to just look at a pack animal who pack weight is similar, 2500lbs is a small pack of [lions](https://en.wikipedia.org/wiki/Lion) or a modest pack of [hyena](https://en.wikipedia.org/wiki/Spotted_hyena#Social_behaviour). for lions territory ranges form 20-400 sq kilometers for hyena 40-1000 sqkm. again this mostly controlled by the quality of territory. Now if we assume your dragons have metabolisms similar to birds that will increase their caloric need by about 10% so I would favor higher estimates. The harder and likely less accurate way is to calculate caloric needs, but is useful as a reality check. luckily for animals there is a rough estimation formula. Kilocalories per day = K^0.75 X bodywieght in kilograms, K is dependant on hte animals metabolism, there is a useful [site](https://www.world-builders.org/lessons/less/biomes/annutrita.html) that has an easy calculator) Placental Mammal K = 72 K^0.75=(24.7) Non-passerine bird K = 78 (26.2) Passerine bird K = 129 (38.2) We should treat your dragon like a non-passerine bird, that is where your largest birds are. so it needs 29475 kilocalories per day. for cattle you can expect about 100,000 calories [per acre per year](https://naldc.nal.usda.gov/download/ORC00000242/PDF) assuming some losses, that includes the acreage you need to farm its feeds so lets half that because your prey animals need to feed themselves. Lets half that again becasue most predators are only successful part of the time so 29475 divided by 25,000 kilocalories per acre per year, (times 365 days in a year)equals ~430 acres or ~ 2 square kilometers. That seems low but remember that is under perfect conditions 100% super productive land, no other predators, no offspring, ect. So our above estimates seem reasonable. [Answer] From wikipedia, female tigers require a territory of about 450km^2. Males require greater territory. That number probably varies greatly depending on geographic area and species, but for now, let's just say that a tiger needs 450km^2 on average. The average tiger weighs anywhere between 90 and 306 kg (198 and 675 lb) (<https://en.wikipedia.org/wiki/Tiger>). So, a dragon is about as heavy as 3.7 chunky tigers, or 12.6 lean tigers. If we scale this directly, a dragon's territory can be anywhere between 1665km^2 or 5670km^2! (1035 and 3523 sq. miles, respectively) A beefy dragon would, going by these calculations, require the entirety of Puerto Rico to itself. A tiny one, however, would only (only?) require an area a bit bigger than Luxembourg. Still, a dragon has the advantage of flight, which would make it easier for the dragon to catch prey. At the same time, flight is an activity that would probably require great amounts of energy, not to mention the fact that a dragon's brain is probably pretty big, which would also consume a lot of energy. [Answer] The beach. All of it. If it were not too demeaning, you could have your condors be beach scavengers. That is not apex predator, but compatible with the traditional dragon and considerable fearsomeness - there is some thought that Thyrannosaurus Rex was mostly a scavenger. I proposed that as an answer here: [Mythical dragon diet](https://worldbuilding.stackexchange.com/questions/140819/mythical-dragon-diet/140852#140852) Large creatures live in the sea and when they die, the bodies can wash up on the beach. Thus a small area concentrates the food productivity of a much larger one, Your dragons could coast up and down hundreds of miles of beach, watching for carrion. A whale would be more than even a dragon could eat at once, and so this would allow you to have dragons with overlapping populations, which mean dragons interacting with dragons which is always fun. Humans (and presumably other intelligent life) likes settlements where rivers reach the sea. Vulture-like dragons might congregate at such places. For a fantasy, a [sky-burial](https://en.wikipedia.org/wiki/Sky_burial) type method of disposing of the dead could be interesting - a tower where the dead are brought for dragons to dispose of. I also liked the ideas of things bigger than whales which might wash up in a fantasy world - true sea monsters. Some of them might have life in them yet, and put up a fight. ]
[Question] [ People of my had come to continent about 4000 years ago, only other races that could not be considered animals and have some significant quantity were dragons and goblins. As those new folks were quite warlike and warable, they'd conquered all of them and promptly enslaved indigenous species. When goblins are perfect creatures to become slaves (not so intelligent, physically inferior and to divided to put some resistance), dragons are another story. Dragons are big, have heavy armor of scales, breath liquid fire, hoard gold, intelligent, spiteful and proud. There was no hope in enslaving them nicely, only heavy chains, cut wings and special drugs could hold them in place with little chance of burning everything around. This mean they're no use as beast of burden, war mount, living attack aircraft and so on. So, there's my question, how to use those those dragons the best in given circumstances? Ideas I had, is to use them as heat sources for furnaces or steam locomotives. Setting we have is your typical fantasy world with technology from XVII/XVIII century. [Answer] Your current dragons are not the same as the dragons of 4000 years ago. Wolves are big, fast, wary, intelligent, eat children and carry rabies. Now their descendants sleep in our beds with us. If you took control of the dragons 4000 years ago, the fact that there are still dragons means you allowed some to reproduce. You chose some of them to reproduce for some reason; certainly you could not have dragons just wandering around, reproducing and eating children ad libitum. You chose dragons to reproduce based on some quality. Probably small size since if you had them captive you needed to feed them which is expensive. Probably disinclination to bite the hand that fed them. Possibly intelligence, which might go back to the not biting hand piece. Maybe if you were a nobleman your daughter was impressed by a dragon you saw in a different castle - a little one, that would do tricks. You borrow that dragon (you have your people borrow that dragon) for stud services because you want one for your daughter. Of all the dragons sired by that one you keep two that seem promising. Other nobles also try breeding dragons because it is cool and they are bored and need something to talk about with their noble friends. 4000 years later the dragons that remain are as similar to the original dragons as dogs are similar to wolves. Unlike the goblins who still live in large societies of their own, the dragons have unavoidably been bred. They are smaller, more docile and much smarter. They are valued helpers and sometimes even advisors. These humanized dragons are afraid of their wild kin in the wastelands and they are right to be afraid. They do not have much in common. [Answer] Meat. Taking their gold. Their bodies could be restricted, only allowed to breathe fire, could be useful to get fires hotter so new metals can be smelted- that would be valuable tech to have. They could be harvested for their scales like sheep- such a material could make valuable armor. They could be in a dragon concentration camp, i.e. only enslaved because they are hard to kill, the task is logistically complex and will take years. They could secrete a special substance that is beneficial to humans (e.g. if you've read Robin Hobb's Liveship Traders series) [Answer] Possibly they would be okay as a source of heat for smelting small quantities of metal, making glass etc. But thermodynamics suggests it's always going to be less efficient to feed fuel to a creature and then have that creature produce heat than it is to create the heat directly. Unless you have multiple dragons you'll never get 100% uptime on the dragonfire because they'll need time to eat and so forth. Overall it doesn't sound well suited to large industrial-scale operations. Your best bet might be that dragonfire has magical properties and is required for certain alchemical processes, or for smelting small amounts of metal that requires to be infused with magic (magic rings, amulets, swords etc.) It's slavery on a small scale and only the wealthiest people can afford to have a dragonforge, because the feeding and security requirements are so tough to meet. Perhaps it's even required that the dragon be required to cooperate in the process, infusing the right magic into an item being created. This would set up an interesting tension: the dragons are intelligent and hate being enslaved, so what hold do the people have over them that is so strong that they co-operate despite the slavery? Does emergent knowledge of that hold then become a lever that could be used by other players in the story? (Edit, to answer the questioner's query about what the hold might be since they've already been subjugated and chained). Well, my proposed use for them was that they are an essential part of the process of making magic items and have to co-operate in order for the magic item to work properly, by imbuing the correct magic. So you perhaps need a stronger hold than mere chains to ensure that these intelligent, once-proud, extremely resentful creatures don't sabotage your magic ring. (A dragon might perhaps, instead of a true +6 ring of dodging, make a ring that appears to be a +6 ring of dodging but which only works when the wearer's pulse is below 110. Thus, in the heat of battle, it stops working and the bearer becomes much easier to kill.) What that hold is, is up to you: it's a plot detail for you as the author to answer, not a world building question. But it's one that allows for some interesting possibilities. If on the other hand you just want dragons as a means of turning meat into fuel, that still seems inefficient when you could just burn wood or coal (growing plant based fuel is much more resource efficient than growing plants to feed to animals to feed to a dragon which in turn will make heat). Yes you might be able to get a hotter flame, but how hot do you need? Ancient people were able to make furnaces well above a thousand degrees to make glass, fire pottery etc. and your world has a 17-18th century level of technology. Short of something a bit more special and unique such as my example above, I don't see why your people would bother keeping them as slaves at all. Except maybe as high status dangerous pets, a bit like Jabba the Hutt's Rancor Monster in Return of the Jedi. [Answer] Frame challenge: what makes you so sure they're still enslaved? 4,000 years is a long time. Maybe there was a revolt, or even just a revolution. Meanwhile, this whole time they have been subjected (willingly or otherwise) to strict control of their nastier attitudes (certainly while they were enslaved this would have included eugenics / selective breeding programs), and over time have come to be less stuck-up to the point that they now work with your other people as friends and (with reasonable concession for physical differences) equals. Of course, this could also still be a work in progress, providing a ready-made source of conflict. You could even have factions of dragons, from "throwbacks" that want to take over the world (or at least have their own nation) all the way to "grovelers" that think dragons are inferior and slavery should be reinstated. [Answer] Scientists(or scholars/researchers) could study these dragons in order to create artifical objects/weapons/armor/machinery based on a dragon's anatomy and biological capabilities. If the dragons are magic creatures they can be used as a magical source, to energize a city's walls or protections. Honestly those are the only options I could think of that doesn't end with the dragon being dead in order to have it's corpse harvested for resources. [Answer] They can be used as an elite transport system, for nobleman or an army. I mean, they are the winged type dragons right? A flying trasport would be very valuable in a 17-18 century society, instead of horses and carts. They also could be used as mercenaries themselves... The thing is how you make them obey their masters ]
[Question] [ In my previous post, I asked about how tall trees could grow in my world. To be honest, I really need those trees to be huge for my storie, because a big part of the plot will be linked to those big forests, so every characteristic of my world are settled for those trees to grow as big as possible (between 250 and 300 meters would be perfect). But I want this world to be believable. A lot of factors influence the growth of a tree, and I have deduced (I am surely wrong) from answers to one of my post [In what ways a higher level of oxygen (23 to 25%) and higher pressure (1,7 time the earth air density) would affect winds and ocean currents?](https://worldbuilding.stackexchange.com/questions/158928/in-what-ways-a-higher-level-of-oxygen-23-to-25-and-higher-pressure-1-7-time/158982?noredirect=1#comment503132_158982) that pressure seems to be a factor to think about (for example higher pressure slows down winds, which affect winds/ocean currents and precipitations, which could, I don't know, allow trees to grow without being bothered/destroyed by a hurricane for example). I decided to think about those trees step by step, so right now, it seems to me that definitely settling atmosphere is the first step. Know that I have a map of my world with plate tectonic, ocean and winds currents and moutain range. Concerning the planet characteristics : what is already settled is gravity (0,8g). But from some research, it seems that gravity influences pressure, because it keeps everything near the planet surface. So I don't know if I can play a lot with pressure. My question is : considering what is influenced by atmospheric pressure (ocean and winds currents, climates - which both influence trees growth - ... etc), how much pressure (kg/m3 or atm) would I need to maximize my trees height ? Thanks ! [Answer] I think the trees can be as tall as you'd like, but they'll start to look pretty different from Earth trees. I spent quite some time developing a world that sounds a lot like what you're working with and have since then taken chunks of that setting and made it more extreme for roleplaying game environments. Here's some of the stuff I did before I added any magic: The trees are all interconnected. At multiple layers. The branches in each layer of the canopy grow into each other and allow forces to be distributed throughout the whole biomass. This shifts wind from being something that might blow the trees over to something which requires much needed ventilation to lower layers. The trees, flora and fauna will grow to optimize this (See also: How termite mounds work.) Think of it almost more like designing a reef than a forest. The trees get big as a team and build their own ecosystem. The trees eat rocks. This one of the ways you can get around the compression and tensile strength of wood. Have it self-petrify. If you're feeling especially serious about it have it grow literal veins of iron throughout and make it natural rebar-reinforced concrete. You could also play with and optimize the grain structure. The root structure is designed to distribute weight at "ground-level" and to penetrate whatever bedrock the forest is growing over. The roots don't primarily absorb water any more, they're there for heavy minerals and structure. The trees get nutrients and water the whole way up. -Lower levels are designed to trap falling debris and form ponds and small lakes with the last of the water that's managed to make it this far down. Roots grow into these to acidify them and break down any biologicals that filter down into usable nutrients for the trees. This layer is its own ecosystem, with fish analogues and very little light. The forest floor is effectively an acid-oozing desert with very little life. -Lower-mid levels are very structural, dropping their leaves and extra branches to facilitate air movement and gas exchange. Depending on the size of the forest and length of day, temperature changes due to shifting sunlight could generate a fair amount of internal wind, which would make this area inhabited by flora and fauna able to hang directly from the branches and get their nutrients from the air (Things like Spanish Moss.) Sections of the tree could have lighter or darker leaves, or flip-able leaves light on one side and dark on the other to facilitate this process. -Upper mid levels are where most of the leaves are. Branches grow more thickly here, full of leaves which trap rain and provide nutrients to the tree and the vast amount of flora and fauna living on this layer. Most of the light gets blocked by this layer, so if you want to have any "normal" Earth surface life you'd probably want to adapt it to live here. Due to the amount of biomass here this layer is where what we would consider soil is deposited. Something like 85% of the water works its way through this layer to be redirected and absorbed by the supporting branch networks. From here build a rain forest with understory and canopy levels stacking in such a way to keep permitting dappled light through. -Upper levels are where the clouds are. The leaves here are for redirecting and taking in water. They are clear and are used for generating alcohols, not sugars. This keeps them from freezing and they sweat the alcohols to lower the leaf temp and encourage condensation. The forest makes its own rain when it needs to. You can get around a lot of the fluid dynamics issues (or at least trade them for different ones...) this way. This is my first answer, I hope I did everything right and it helps give you some ideas. Thanks for building what sounds like a really cool world! [Answer] There are a number of issues to overcome with giant trees. The first is the force of the wind. Any storms will have a disproportionately larger effect on taller trees. This might be aided by a less dense atmosphere. Additionally if the day length was longer than on Earth it might help as one of the major drivers for storms is the difference in atmospheric speed between the poles (0 miles/hour) and the equator (1000+ miles/hour). Just to be on the safe side I would also plan your forest to be in a low wind area free from the worst effects of whatever storms there are. Another problem is getting water and nutrients to the top of the tree. I suggest having a traditional tree structure with plenty of deep and well spread roots. But the tree will eventually struggle so I suggest having additional sources of water and nutrients delivered at high level. Water could be collected from rain into bowl shaped structures on branches and on the trunk especially where branches met the trunk (for stability). If there was enough rain these would regularly be topped up and would become colonized by plants, insects and animals. The influx of dead leaves, decaying vegetation and animal/bird waste would make an ideal place for the tree to send out high level roots for added sustenance. One further aid would be strong evolutionary pressure to grow tall. Whilst this would be natural for trees, indeed its competition for light that forces them higher, but perhaps the animals/birds prefer the very tallest trees for some reason. In this way the tallest trees would get the most nutrients. Finally gravity is problematic. You have helped by reducing gravity to 0.8 and by having low level winds, but some structural changes would also help. Very large buttress root supports would be expected so the trees would be wide and have an irregular cross section at the base. Stronger natural materials might also help. Perhaps the wood might incorporate proteins like spider silk to greatly improve strength. ]
[Question] [ In theory, could any organism using protein folding or another biological process “assemble” the diamond allotrope of carbon, if it were at the correct pressure to do so? In other words, could some organism (or colonial organisms?) exist which has grown diamonds analogous to how an oyster grows pearls? In essence this question comes down to having the right binding energies and sites to make molecular assembly work. And it does not necessarily mean doing this one atom at a time. Even some method of attaching a hydrocarbon or CO2, then stripping away the "impurity" might work? [Answer] In theory, diamond growing is possible Diamonds are famously hard, but when you get down to the molecular level, it's nothing particularly impressive - just a carbon with four carbon bonds. The standout is that a diamond consistently has these kinds of bonds across the entirety of the diamond. Now, a carbon-carbon bond is very easy to do - the body uses enzymes to do it all the time. All you would have to do it keep building a lattice of these carbons over and over - it's something the body can do. There's no reason an extremophile can't make one. That said, it's a waste of energy and resources. To make this, you'll need to take a carbon bonded to something which isn't a carbon, and turn that into a C-C bond, which isn't easy to do (read: endergonic reaction) and it's very not easy if it's, say a C-H bond. Something like a C-O bond, or even better, a C-X bond, X being a halide of some kind. And it's a complex process. To make artificial diamonds, they take carbon, and they subject it to vasts amount of heat and pressure - to the point where it was the [biggest explosion on Mythbuster's history](https://www.youtube.com/watch?v=_0UOB50Otok). That's the kind of energy we're talking about - it's not something to toss around idly. (P.S. - That clip is a bunch of Mythbuster explosions, followed by the mother of all Mythbuster explosions. You want to watch it.) [Answer] I don't see why an enzyme couldn't produce any allotrope of carbon you can think of. It might take a lot of energy but ultimately it's just playing with carbon bonds and if there is one thing biology is good at it is manipulating carbon. And there is no reason to think that high pressure would be necessary. Enzymes catalyze many reactions that only happen spontaneously under extreme conditions. ]
[Question] [ So I'm writing a gag comic about a superhero blessed with a plethora of abilities collectively called "Omnipotence" but with it comes two catches. 1. Everything that is directly or indirectly affected by any of his abilities will be fixed if broken after a couple of second. All living organisms are excluded from this rule. 2. This is what the question is about : Everytime he uses his powers, Everything connected to that specific event from 30 minutes to the moment he switches off his powers are wiped from the memories of every single person involved. He calls this the "Flashbang" effect. In essence, after every problem he solves, all evidence and memories connected the problem he solved disappears. Like, it never even happened in the first place. So, if he jumped infront of a moving vehicle to save an old woman being crushed by it: * The dent in the car will be "fixed", all the broken glasses from the windshield will return and fix itself. All after a couple of seconds * Everyone who saw this happen will lose complete memory of it even happening. In the end, he is always forgotten. To my question. I do understand that this a gag comedy comics, but I'd like to get this concept right, since most of my world building will be centered around it. *How will this forced Memory loss work?* [Answer] There have been studies that show it is possible to [alter hippocampus related memory in a number of ways](https://www.sciencedirect.com/science/article/pii/S0361923013002074). The repertoire of methods employed is expanding and includes optogenetics, transcranial stimulation, deep brain stimulation, cued reactivation during sleep and the use of pharmacological agents. In addition, the possible mechanisms underlying these memory changes have been investigated using techniques such as single unit recording and functional magnetic resonance imaging (fMRI). It could be as easy as your hero having a field that he emits when using his powers that has an effect like this on everyone in the area which keeps short term memory from sticking, like a very brief amnesia. [Answer] Let’s turn to everyone’s favourite: Swelling of the brain This particular guy’s superpowers cause the emission of a funky exotic radiation that causes localised swelling and temporary damage in the areas of the brain responsible for memory. This causes ~~uncontrollable seizures~~ retrograde amnesia! Short term memory is completely compromised, and thanks to the interaction of the radiation with various neurotransmitters, any areas of long term memory that are activated at the time of the event (say your memories of the old lady’s name) are also mildly damaged, causing subjects to completely fail to remember important details about the event unless reminded about them in a different way (memory is weird). As this doesn’t damage anywhere else in the brain (thanks to the well studied effects of Comic Book Science) the subjects can continue acting entirely normally for the duration of the super-event, but have no episodic memory or linked memories of the event itself. They also don’t suffer any of the more deleterious effects of brain trauma, like permanent loss of function, fatal aneurysms or seizures. Side effects do however include people who aren’t direct witnesses also losing chunks of memory (as the radiation isn’t directional), and repeated exposure causing more permanent damage to long term memories. Also the occasional seizure in those of abnormal brain makeup that might otherwise be immune. Being this guy’s super-teammate is a very, very bad idea.. ]
[Question] [ I want to build a world that has its geographic poles travel like the Earth magnetic poles do. What is a plausible way to do this? (besides giving it two suns that is) [Answer] Earth's poles already do this, so you're set. It is referred to as "[nutation](https://en.wikipedia.org/wiki/Nutation)" (as well as "precession" and "wobble"). The effects are caused by many things, including tidal forces and, strangely enough, differences in ocean pressure. Basically, the Earth is not a perfect sphere and even if it were it has various dynamic processes going on (like the fact that the oceans are not uniformly deep, the core is molten etc) that cause it to subtly change its axis. Now, if you want a very pronounced nutation or precession, you probably need a HUGE influence by an external body, probably to the point where tidal forces dominate anyway (see [here)](https://en.wikipedia.org/wiki/Axial_precession#Cause) [Answer] Geographic poles are the point where the rotational axis of the planet intersect its surface. If you want the geographic poles to move, the rotational axis has to change. A possible way to make it happen is to have the planet experience internal motion of large masses. This motion, altering the momentum of inertia, will move the rotational axis. ]
[Question] [ I am developing setting for a dnd campaign I like to run next year. Its takes influences from Xenoblade 2, where people live on or inside humongous creatures while the entirety of the world is an endless sea. One thing that I am stumped on, is where would society get non-organic materials, such as Iron, Copper, Gold, etc. I do not like to use the Scavenger mechanic from the game. [Answer] Some elements might naturally accrete on the ocean floor like manganese nodules. These contain a wide range of metallic compounds like iron, chromium, etc and are a potentially valuable mineral source. Your creature-cities might be taught to dive deep and collect these nodules for their symbiotic inhabitants — or parasitic inhabitants as the case may be. And, some fish might absorb metals through the water to grow stainless steel teeth for biting through tortoises shells or super hard crustaceans. These fish could be hunted and harvested for their razor sharp corrosion resistant teeth. Other fish might absorb metals to form their scales. These might be ranched and shorn like sheep for their coppery and tin scales, then cast back into the water All the compounds and elements might need alchemical processing to purify them and convert them to a form they can be used for construction or metalwork. [Answer] Interesting metals are dissolved as salts in the water (google the worlds' oceans content of gold, or uranium). The huge animals everyone lives on drink the sea water and extract these elements. They can be mined by cutting organs or body parts from animals and burning them, the resultant ash is your ore for further processing. Some body parts may contain noble metals in their pure form. Maybe gold or silver or even copper are slightly toxic to the creatues in their dissolved form, so they are sequestered in special kidney or liver like organs? IRL diamonds form under immense pressure, on your world diamonds could be a form of gall stones. IRLS animals use mostly calcium (not quite a metal, chemically speaking) for bones, other metals might show up in bones of huge fantasy creatures. I suggest you take thse ideas, think through the implications and the optics (do you want proud gall bladder miners in your world? Or dungashers, who burn the dung of these creatures for ore?) and see if they are fun and make sense in your game world. [Answer] If you cannot go outside to harvest materials, then the only way is for your creature to eat the materials itself. We could use the behavior that some land animals use to get access to salts vital to their biology (just google salt lick). Instead, your creature consumes parts of the sea bed to obtain vital nutrients (the animals they eat might be attached to the sea bed as well, or have homes inside, and the animal has simply evolved to take a chunk out of the sea bed). When it consumes this, it also swallows any non-organic materials within the sea bed and your people harvest this. Alternatively, your creature might consume trace amount of elements which are filtered out by the body. Overtime, the non-organic materials form into small balls, stones or piles that your humans can harvest. [Answer] Harvest metals from the dead. [Removal of metal ions using an industrial biomass with reference to environmental control](https://pdf.sciencedirectassets.com/271815/1-s2.0-S0301751600X00191/1-s2.0-S0301751697000616/main.pdf?X-Amz-Date=20190903T141210Z&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Signature=1ee384df420ef93102e43f38616758b499ed2606318d119444206e1939c6fcd0&X-Amz-Credential=ASIAQ3PHCVTY7H4Q5DUZ%2F20190903%2Fus-east-1%2Fs3%2Faws4_request&type=client&tid=prr-97469d22-362b-4494-ab84-c79839072987&sid=1b1f1cd220abf346975a22f5281ce0e67496gxrqa&pii=S0301751697000616&X-Amz-SignedHeaders=host&X-Amz-Security-Token=AgoJb3JpZ2luX2VjEF0aCXVzLWVhc3QtMSJIMEYCIQC0bXP3XDkF%2F6V0vKGYmNzbJatyXLH5X13w1bnRXIW4FAIhAMNzgfHxDeJL390f3CsBSlfO9g1XPkv9Jr1Dx6ovS6qSKtoDCBYQAhoMMDU5MDAzNTQ2ODY1IgzFiXFoLaxboo40MIcqtwMcIBpCcyZHCroOKFTEr7SwPhsL3fe%2BmZg3rEwGRn1Xn0Lz2GSjhnc8Ae1PyHoXnCUjTnqdagRlQNYY66G5K8uiK%2FY8M6Y2TGjYPrWkaMBME4YP4c4ibCVSnM90x2gpvey3BUIRNFXyHiDaxNRYyIcthAQ1IzEwjkyZzgO6fZ8kwAPKuYJsta%2FR10D7fja87qCKSB1X%2BGghF6TRvvXpHuzUhwbhMqIBNqehGvFZ9RXbvgw44evJFlf%2Ff1VunXV13PfEiSWMC34AENQP3oZo2wfqBmSpyH93srS3HYsQLskdgmVGydXt16O%2BmUlaxkXP4akvU60MTHkeTkrPCW8oMsULgU%2BWlGRCdEG6cRfGHFAjBMFtAXKp6SPGKIeSDYzI5RMm7ofn7bKRgALaXCXeIKkRqxGHSe8cOnCkaNVoNx3gav%2BYJ1dLKYGkgoHxUWAIqPM1vr0n3%2BAC7g3X25qgqGzIDs0WNe41K8SlbBJJ5bUIC%2Bhdtzfx6uNHh1%2BXobPyH2U3oLvMk%2B%2FjkeKEr%2B07nUtGfu4cbeqwu9lmTQRCF3S1I3eyITaAEB2c1r%2BPyvgS8qR48b1DAtSyMK3IuesFOrMBe8kMB8MYXaVcCQCtED1BdlR9qBQ9umpfkJNWfB2TUiS2f0eKwHgw%2FjoFvYJ%2BkK4Spik8tqWPw%2F%2F0mvHXf8cTV7JgElsmp3wh3CkyHw2FYc2WlsyE%2BybV2YjJAseC5EBqGWDOEGS9ymIeMf6AY8fHIjtHXv7ML41wvFvDtAl25ro3QCLmPqU577V26TIBgV%2FrTvtYpFS96AcSDL18ITiHZYSAQwmBaaTJID0lZOX9%2FWZzEZg%3D&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&X-Amz-Expires=300&hash=d593dded43ede36090e057bf97942763614b5994171f198bcd57bec5f42913c8) > > It is well documented that microbial biomass is capable of absorbing > metal ions from aqueous solutions even when the cells have been > killed... The biosorption of metals using non-living biomass has > recently been comprehensively reviewed by Modak and Natarajan (1995). > The use of dead biomass eliminates the problem of toxicity and the > economic aspects of nutrient supply and culture maintenance. > > > Your seas are rich in mineral salts. Water dwellers must exclude these salts from their bodies or they will accumulate to toxic levels - this is exactly the case for fish and other higher animals in Earth's oceans, which must keep the salt from the ocean from entering their bodies in excess. But once dead, the energy to expel salts is gone, and dissolved materials will accumulate, binding to organic molecules and possibly even crystallizing within dead tissues. The linked article uses that phenomenon to clean wastewater streams. In your world, dead creatures accumulate metals from the water. The longer they have been dead the more inorganics they have accumulated, until they start to fall apart. Dead things might also stop floating and sink as they get heavier, but a floating dead leviathan is also a good anchor for plants and photosynthesizers. An attached colony of kelp with air bladders could keep the corpse afloat for a long time or even indefinitely. The plants might give off chemicals to suppress decomposers that will destroy their dead float. Also sentient organisms might make constructs to augment the buoyancy of dead things, to facilitate repeated metal retrieval trips. In your world, floating kelp colonies have one or more skeletons and corpses, ancient or fresh at their center. Your characters will need to get in there to retrieve metal crystals. A fresher corpse might also have scavengers interested in the meat and ready to fight off intruders. Other things might have taken up habitation in such an ecosystem. [Answer] In your world, the humongous habitat-creature could start out as a small deep dweller which is connected to the deep sea bottom via feeder tentacles, moving over the bottom to collect nutrients. As it grows, methane and pure size force the creature to slowly rise to the surface, the feeders growing at a proportionate rate. The creature will therefore always be connected to the oceanic floor, sucking up nutrients like a gargantuan vacuum, and alongside with the organic material, metals and other debris is sucked up and fed into the processing organs. Your people would extract these materials and waste products before they are disposed of through the creatures waste organ. [Answer] Trade with aquatic people. If there are water breathing species that can mine the bottom you could trade with them. Bonus points if they are unable to use fire so your protagonist civilization is the only ones able to craft metal. That would create a mutal trade dependency. [Answer] To add to other answers: some meteorites are from metal (mostly iron), others contain carbon with other minerals. So, occassionally, a chunk of material may just drop from above. ]
[Question] [ Could there arise naturally a plant that like mistletoe attaches itself parasitically to an oak tree that can interbreed with a regular apple tree, and produce fruit that are very similar to apples? [Answer] ## Possible but not likely for a number of reasons: Plants don't interbreed unless they have a recent (for varying values of recent) common ancestor. Also, the ancestor should, in fact be an actual apple tree since you want a similar fruit. It could develop a similar looking fruit on its own but that just makes it more unlikely to happen. Also, an apple is the wrong kind of fruit for a parasitic plant. Parasitic plants have their seeds dropped onto the tops of trees (often through bird droppings) or they are light enough to be carried on the wind. Since apple seeds aren't going to be flying up into trees (barring traumatic wind storms), you will need some creature that eats apples and then climbs (or flies to) oak trees to defecate. The feces will have to be sticky enough and contain enough nutrients to allow the seed to stay in the tree and grow until its roots can secure it in position. Also, if the apple plant is to be truly parasitic and not just using the oak as an anchor, it needs to learn to deal with an acidic environment. The reason nothing grows around an oak is that the dropped leaves poison with soil around it with acid. If the apple is just anchored to the oak, it needs to learn how to draw moisture and nutrients from the air. It would be helpful if some critter nests among its roots so the critter's droppings can provide nutrients. Now, if too many changes are made to adapt to its new environment, it is unlikely to be able to interbreed with the original apple trees. The only way that I can see is if you introduce one or two creatures (drop the seeds in the oaks and fertilize the plant) and the apple uses the oak only as an anchor. This would mean that it is one apple tree that lives in two environments. Over time they may have slightly different shapes if the tree adapts in a way that causes it to not grow as tall (and bushier) if its roots are not in soil but that's as far as it is likely to go without someone tinkering with it. [Answer] Short answer: Yes. Long answer: So: there already exists the art/science of grafting, where a small plant cutting or branch is fastened to a second compatible plant and continues to grow there. Typically when it comes to trees this is done with citrus fruits such as orange, lemon and lime, but apples aren’t that far away (evolutionarily speaking) from the citrus fruits and they have a whole slew of other similar trees they can exploit. This means we can happily imagine an apple-esque tree that is capable of growing using the support systems of another tree. But wait! There will be compatibility issues. Not all plants can successfully graft to other plants. But you did bring up the example of mistletoe, right? So if our mutant apple tree has an invasive root system as well as being happy to ‘graft’ itself to another tree it can support both modes of survival. Initially parasitic (in as much as it steals water and nutrients, it makes sugars itself) until it gains enough of a foothold to properly integrate itself, then firmly entrenching and becoming a ‘part’ of the tree. The more close/compatible the tree the better. The biggest problem I think you would have would be spreading. You have to somehow spread your seeds (contained within a heavy fruit) near enough to another tree (preferably high up so you can get sunlight) that they can root in the tree. Bird excrement would be an excellent way to do this, but birds pick at the flesh of apples more than the seeds. An arboreal mammal like a monkey or lemur would probably be your best bet, as they’d eat the delicious fruit, do their business on other trees, and perpetuate the fake apple cycle. Incidentally, monkeys and lemurs are common in Asia. Guess where the apple originated? Yup. Asia. So the answer to your question is yes. It’s plausible. Plus it’d be nice to be able to turn any tree into an apple tree. [Answer] There exists a thing called the oak apple gall. [![oak apple gall](https://i.stack.imgur.com/PFx39.jpg)](https://i.stack.imgur.com/PFx39.jpg) The galls are produced by a larval insect which hijacks the oak tree to make itself a case to grow in. Instead of some genetically cumbersome mix of parasitic plant and apple tree, have there be oak galls that are edible. I can imagine an insect which does the same thing and creates an apple-like edible gall. This would be an insect which hopes an animal will eat its larva (thus the fruit) so it can grow parasitically inside the animal - maybe an insect with 3 life stages. People in your world can remove the larva first or cook the fruit to avoid infection. Or maybe infection is not too bad and they consider it a fair price to pay for delicious fruit. ]
[Question] [ Basics: There is a wormhole in a fixed position within a solar system. It is roughly 40 million miles from the orbit of the habitable planet, which kind of mimics Earth (roughly 12 month solar orbit at a distance of 90 million miles, etc). Ships typically travel from our Solar system through said wormhole during a specific window and arrive at a time where the planet is approaching its closest point to the wormhole as this is the most cost efficient journey. What I can't seem to get my head round is the speed, acceleration and deceleration. So how fast would the ships need to accelerate, to what optimum speed, before slowing down and the rate of deceleration required to avoid turning the humans inside the ships into jelly. Would it make more sense to continue acceleration to an optimum speed and then immediately switch to deceleration, or accelerate at a faster initial rate to an effective "cruising speed" and then hit the brakes closer to the target? Ideally, I'd like them to make the 40 million mile journey in about two weeks. [Answer] TL;DR: For your journey, a rocket that does a short boost, coasts for two weeks, and does another short boost is much more efficient than one that runs its engine for the whole two weeks. It can make do with a much less exotic and power-hungry engine, or vastly less fuel. It also makes provision of artificial gravity simpler, and relaxes debris shielding requirements. Its higher thrust also makes orbital manoevers more straightforward. In neither case do you need to worry about mashing your passengers. --- > > Ideally, I'd like them to make the 40 million mile journey in about two weeks. > > > There are (very, very loosely speaking) three things you can do here (there are other options, but they'll take far longer than you want, so I'm ignoring them). 1. [Hohmann transfer](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit) (as puppetsock mentioned). This involves injecting yourself into an elliptical solar orbit with an [aphelion](https://en.wikipedia.org/wiki/Apsis) that juuuuust reaches your target's orbit such that when you reach the aphelion your target reaches you. You boost twice, once to inject yourself into your transfer, and once to inject yourself into an orbit around your target (or, if your target isn't really massive enough to be orbitable, you inject yourself into a solar orbit that matches it). 2. Use a Moderately Powerful Rocket Engine to push yourself into a faster intercept trajectory, at the cost of using somewhat more fuel and/or requiring a more powerful and efficient rocket. The aphelion of your transfer orbits reaches much further out, and you're travelling much faster when you approach your target, so you need a beefier engine to slow yourself down. 3. Using an Outrageously Powerful Rocket Engine, blast yourself into a hyperbolic solar escape trajectory which happens to intersect your targets orbit as above. Then you blast yourself into an appropriate rendezvous orbit. Optionally run your engine up as far as the half way point, then flip over and run it again to slow you down to the intercept point, depending on how much excess fuel and power you have. You've already kinda ruled out 1, because given your earthlike system and your 2 week requirement you'll never have the patience. A Hohmann transfer to Mars (a bit closer than your target, as its around 35 million miles away at a closest approach) takes over 8 months. You've already basically ruled out 2 as well, as you can squeeze transfer times down to about 3 weeks that way. That basically leaves 3, which obviously requires an OPRE. What's left is to establish exactly how outrageous your rocket is. Lets break out good old Project Rho, and fire up the [Brachistochrone Equations](http://www.projectrho.com/public_html/rocket/torchships.php#id--Brachistochrone_Equations). These describe a continuous acceleration trajectory, which is a nice easy thing to work with. I'll use sensible units, so your flight distance will be a user-friendly 64373760km. $$ T = 2 \sqrt{ D/A } $$ Where $T$ is time, $D$ is distance and $A$ is acceleration. If your rocket can manage a whole 1G of acceleration (and this is no mean feat) you could do the trip in 2 days. So that's a bit excessive. Rearranging to get $A = D/(\frac{T}{2})^2$ where $T$ is two weeks gets you a nice, relaxing $0.18m/s^2$, or a mere 1.8% of earth's gravity, as the required constant acceleration for your trip. As an alternative, if you use your 1G rocket just to boost you up to a cruising speed (and to slow you down at the end) and then coast for the rest of the time in microgravity, you can use a slightly different version of the equation: $$T = \frac{D - A t^2}{A t} + 2t$$ where $t$ is the time spent boosting (or braking). You can rearrange this into a nice quadratic, $Tt-t^2 - \frac{D}{A}= 0$ which you can then solve to get $t \approx 5500s$ (or a little over an hour and a half of comfy acceleration to start and the same to finish, bracketing nearly 2 weeks of microgravity). --- Why would you prefer one over the other? Lets think about $\Delta V$ (that is, the totaly change in velocity required during your trip). For both trajectories, there's a constant factor... you've got to inject yourself into a solar escape, and then inject yourself back into a regular solar orbit. To escape Earth's gravity from low earth orbit, you'll need at most $~3km/s$. To escape the Sun's gravity from Earth's orbital radius is a further $16.6km/s$ and to inject yourself into a Mars-like orbit you'll need another $11.2km/s$ for a total of $~30.8km/s$. Note: for your "fixed" wormhole, that final manoever will be rather different, but as I don't know how something could possibly be "fixed" I can't tell you what the total value would be. Everything is simpler if it just orbits like a sensible mass. The continuous 0.018G trip needs $\Delta V = 2\sqrt{DA}$ which is about $213km/s$ on top of that constant amount. The boost'n'coast trajectory on the other hand needs $\Delta V = 2tA$ or about $107km/s$. That's a pretty serious difference! This means that the continuous thrust option either needs quite a bit more fuel, or a much more powerful rocket. Given that $\Delta V = V\_e \log\_e(R)$ (where $V\_e$ is the exhaust velocity of your rocket and $R$ is the ratio of the fully fuelled mass of your ship to its dry mass), using the same exhaust velocity the continuous boost trajectory needs 10 times the mass ratio. That means either tens times the fuel, or a much smaller payload (just one tenth, and probably smaller because you still need the same engine...). Alternatively you could use a rocket with twice the exhaust velocity, but that's easier said than done... doubling your thruster power whilst maintaining the same fuel expenditure means that your cooling requirements have now gone up (because you can only dump so much excess heat into your reaction mass) and so you'll need bigger, heavier heat radiators. You need bigger reactors (which are heavier, obviously) or more energetic and efficient nuclear engines (probably also heavier). All that extra weight eats into your useful payload, and that's clearly undesirable. Next, shielding (note: I'm again ignoring solar escape velocity here as a constant, but you might want to take it into account). Your constant boost ship reaches a top speed of a little over $106km/s$ , but the boost'n'coast ship only reaches $~54km/s$ (but of course reaches that speed much quicker and sustains it for a long time). By reaching only half the speed, the kinetic energy of impacts with the same mass of debris are reduced to a quarter. That means you don't need as much shielding, saving weight to use on useful payloads. Additionally, your continuous boost trajectory means your ship must stay pointing in the appropriate direction for the entire flight. If you want artificial gravity, you need a centrifuge. This are heavy and inconvenient and you need to make sure they're shielded from any radiation your drive is producing. Your boost'n'coast ship, on the other hand, can point whichever way it feels like, and this lets you use a ["tumbling pigeon"](http://www.projectrho.com/public_html/rocket/artificialgrav.php#id--Spin_Grav_Types--Dependent_Centrifuge--Tumbling_Pigeon) artificial gravity technique. Not only is this mechanically simpler, but you can also use a much longer diameter on your "centrifuge" letting you reduce the unpleasant coriolis effects and keeping your crew happier as well as healthier. Finally, there's the small matter of manoeuvres. Really, you want your orbit-changing manoeuvres to be done instantaneously, but generating infinite accelerations is awkward. If your engine can't generate sufficient thrust, you end up doing a slow spiral-out (or in) rather than just blasting yourself into a new orbit. The 1G engine will take you from LEO orbit to Earth escape in a little over 5 minutes, which is much less than a single orbit. This is nice and prompt and efficient (and lets you make use of tricks like the [Oberth effect](https://en.wikipedia.org/wiki/Oberth_effect)). The 0.018G engine takes nearly 5 hours to reach escape velocity, which may require multiple circuits around the planet (and possibly through the radiation belts, if you're not careful). These are all important issues for real world spaceflight, and maybe you might care about them too. --- Edit: just remembered that I said we were going to find out just how outrageous your OPRE would need to be. Well! Lets just concentrate on the sensible boost'n'coast rocket. Again, I'll lazily elide the effort required to break solar orbit and park at your destination. If you wanted a mass ratio of about $e$ (eg. your fully fuelled mass is about 2.72 times heavier than the dry mass), $V\_e = \Delta V \approx 107km/s$. That's high, but not crazy high. This is in the realms of nuclear rocketry... a refined [Orion Drive](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) could manage it, certainly. It would have enough thrust to do the job, which is the most difficult requirement, so congratulations: your OPRE is almost achievable with modern-day technology! A nuclear electric plasma rocket might be able to do it, but getting a beefy enough lightweight and efficient nuclear reactor (might have to be fusion with [direct energy conversion](https://en.wikipedia.org/wiki/Direct_energy_conversion) ) and a powerful enough plasma engine might be tricky... but y'know, you've got wormholes so maybe you'll be fine, tech-wise. Remember that you'll have to refuel when you reach the wormhole, but flying out extra fuel and reaction mass via slow, efficient bu human-unfriendly orbits will be straightforward. If the dry mass of your ship (engine, hull, life support, crew, cargo, all the rest...) was about 1000 tonnes, it'd be about 2720 tonnes fully fuelled. For the orion drive, that's quite a substantial number of nuclear weapons, which will give you a good way of visualising Niven's Kzinti Lesson: "a reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive." The engine would need to develop a thrust of $F = MA = 26MN$. That means the rocket power is $F\_p = (FV\_e)/2 \approx 1.4\10^{12}W$ or a 1.4 terawatts... if it is 100% efficient* which clearly the gods of thermodynamics are never going to allow. So 1.4TW is a minimum power. And that is why I called it an Outrageously Powerful Rocket Engine. ]
[Question] [ OK - breakdown in society - economic apocalypse in 2030 - society breaks down and the supply chain of what we take for granted fails. 200 years later we have regressed to a technological period of around 1300, however some things have survived - for example the knowledge that bacteria and viruses kill - metallurgy etc. But the destruction of supply chain has resulted in falling back on older tech. Let's say that by 2030 a cache of oil stored modern firearms has been found (to keep this simple - lets say bolt action military rifles like the Mauser or Lee Enfield SMLE - STEN sub machine guns, Webley Revolvers). Now in theory. provided the weapons are stored in oil they should be fine with a clean - but what about ammunition? Ammo for these weapons was usually shipped in sardine can type packs in wooden and steel sealed boxes. Would the propellant in the cartridges have survived 200 years or would there be too many corrupted cartridges to risk an unacceptably high incident of misfire? Secondly - with the rifle and revolver - would it be feasible to replace the propellant for black powder (can see problems with the primer here as from what I understand, it is the primer that would most likely fail over time). OR - Would older tech - longbows/crossbows - be more reliable. In a society like the British Isles, where there are very low firearm stocks outside military use, and most of those shotguns - I would like to think that after 200 years that bows would be back in use - perhaps the shotguns could have been converted to a match or flintlock - the barrel being the most complex part of any firearm to engineer and very difficult to do so without specialist machine tooling. any suggestions? [Answer] For the Webley and SMLE, the rounds were originally loaded with black powder, and there's no good reason a Sten couldn't work (for a magazine or so, anyway, before cleaning) with 9 mm cartridges loaded with black. On the other hand, even corrosive primers won't last two centuries, so just pulling down the ammunition and replacing the propellant with black powder won't solve the reliability problem. Military ammunition as little as fifty years old is unreliable, even when pulling down rounds doesn't show any degradation of the powder itself. Plain old misfires, and worse (from a safety standpoint) hangfires as long as several seconds become distressingly common. What the cache could provide, to people capable of understanding what they've found, is the exact specs to produce their own ammunition. They could use the brass (or steel) cases, make their own primers (once they rediscover the idea and have examples that work sometimes), load with black powder, and be ready to fight. I don't know whether this could be done with 14th century technology, however; even their black powder was pretty dreadful stuff compared to modern Goex, Swiss, or Elephant Brand (they hadn't even discovered incorporating, never mind pressing and corning), and you'd be calling on alchemists to step to make the priming compound (which would almost certainly have to be a fulminate base at this level -- those were the first explosives, in the real world). [Answer] If you allow for a system, perhaps powered by a massive radioactive source, which maintained cryogenic temperatures, it's at least more likely that standard ammo, plastic explosive, etc. might survive without significant degradation. [Answer] Thanks for your responses. Ironically, you'd probably be better off with a flintlock weapon than a cartridge or percussion cap weapon. From my own research (British Muzzle Loaders - a wonderful Youtube channel run by a Canadian chap who has thoroughly researched the drill, life and weapons of imperial soldiers from about 1800 to 1900 has been extremely valuable) you can chart the development of firearms as machine tools and metallurgy advanced in the 19th C The biggest challenge in making any fire arm is going to be machine tooling and the quality of the steel going into the stressed parts, never mind the precision required. The technological leap from the Brown Bess style military musket (the main infantry weapon of British forces from 1740 through to 1815 (dates are my own guestimate) and the Baker rifle that Sharpe uses in the books and on the telly is a considerable one primarily because of the tolerances demanded by the rifle and the quality of the barrel, Today you can buy a kit to build a Baker rifle from a company in Canada. The only thing not included is a barrel - for this you need to go to a gunsmith as it is the barrel that requires the specialist engineering bit and because you don't want to kill yourself with an exploding breech. I think a good starting point over the 'cobbling together' of weapons could be the Afghan jezzail, the often home made rifle made by the tribesmen of 19th C Afghanistan. These were usually built by local craftsmen and the firing locks found are a mix of matchlock and flintlock, percussion locks start to make an appearance. Early on the firearms are almost all matchlocks, a matchlock is a relatively straightforward thing to make, a tinsmith might be able to cobble together a crude one. Flintlocks in these weapons have machined parts and require a spring - again a sophisticated bit of metal, needing high carbon spring steel - making such by hand is a specialist job as any watchmaker will tell you. The reason why we start to see such in many Afghan made weapons in the mid to late 19th C is due to recycling flintlocks from British and Russian made weapons. However, the more skilled artisans would have been able to make the locks and springs but I suspect that in most, springs were recycled from captured or salvaged British weaponry. The wheel lock is a sophisticated and complex design requiring again, sophisticated metallurgical skills and and understanding of clock work. If drum springs could be found then there is no reason why a crude matchlock couldn't be made. As to the primer issue - this is the biggie and this is the thing that really rules out cartridge weapons, black powder or otherwise or percussion caps - never mind the skills required to produce machinery to make the actual caps themselves. So I reckon that in reality, any cartridge weapon of 20th or 21st C design is going to be obsolete in a post apocalyptic 2230 because of the primer isssue. Gunpowder is also an issue - sulphur being the major headache. Throughout the gunpowder age in Europe, the primary source of sulphur were the sulphur mines on Sicily in the vicinity of Mount Etna. Saltpeter and carbon can be extracted from local sources (local = Scottish Highlands and islands in the setting of this book) but sulphur is an issue. Now, such would require relatively sophisticated and extensive pan European trade routes however, 200 years after a population destroying non nuclear apocalypse As to gunpowder quality - IF the effort of building a firearm as described above is deemed worth it then there is no reason not to think that such would not exist. I am a trained archaeologist and there's ample evidence of fine axe heads from what we now know as Wales, being traded as far a field as modern Russia during the neolithic period. Flint mines in southern England supplied quality flints across Europe for a period of 50,000 years or so and the discovery of a stone age sea going trading boat on the south coast of England indicates that such trade routes were commonplace for desirable or essential materials like quality flint. Corned gunpowder would not be beyond the skills of someone who knew their history, it merely requires adding water to the blended gunpowder, forming it into cakes before crushing it and sorting the larger corns from the finer ones using a sieve to get your different grades of powder (priming powder vs charge vs cannon charge vs explosive) corned powder is a much better prospect than uncorned especially for those who need to travel. Sten guns with black powder? I suspect they would probably jam due to fouling of the barrel after a magazine worth - one of the reasons why gatlings etc used multiple barrels - also is the pressure from black powder enough to drive the bolt? I wouldn't know. So looking at all the above, a more feasible projectile weapon would probably be the crossbow. Which is, after all, a 13-14th C in its final widespread military use. Tests have shown that a hand cranked crossbowman can lose around 8 bolts a minute when working at top speed (about half that of a semi competent longbow archer) Yes crossbows require some skills to make but are not beyond an artisan. They are easier to use than longbows and do not require the years of dedicated practice longbows require composite bows again, are not beyond a skilled artisan. Horn and suitable wood can be laminated together with a glue made from boiling fish air bladders. They might, however, suffer in the damp climate of Scotland. ]
[Question] [ This is Yeola~Camay. A double planet orbiting Sharro, an ordinaryish star somewhere in the universe of [Far Far Away](https://cbb.aveneca.com/viewtopic.php?f=24&t=4585). [![enter image description here](https://i.stack.imgur.com/wI8hh.jpg)](https://i.stack.imgur.com/wI8hh.jpg) As you can plainly see, Yeola is the planet on the left & Camay is the planet on the right. Here is a map of Narutanea, the Eastlands of Yeola: [![enter image description here](https://i.stack.imgur.com/OesT6.jpg)](https://i.stack.imgur.com/OesT6.jpg) East is to the right, west is to the left. The markings around the edges of the map show degrees north of the equator and east of the prime meridian. The space between each is six degrees. The land to the south of the Sea of the Moon and to the west of the Ocean of Sunrise is labelled *Auntimoany* and its chief city is Pycleas. Pycleas is roughly 24 deg north and 36 deg east (close enough for government work!). (This is point of interest no. 1). Directly to the west is the country of *Harathalliê, where you can see a lake. In the vicinity of the lake are the West Downs and the old North Tower. (This is point of interest no. 2) The two locations are about 1200mi distant, as the raven flies. This is a map of the night sky, centered at the ancient observatory just west of Pycleas: [![enter image description here](https://i.stack.imgur.com/jlQ1V.jpg)](https://i.stack.imgur.com/jlQ1V.jpg) If you lie on the courtyard of the Observatory with your head towards the east (right side of the map) and tilt your head back, you'll see the red gash of The Chasm down towards your right hand and you'll see a portion of Camay above your head. This is a map of the eastern sky, showing approximately what an observer would see looking out east over the waters of the Ocean: [![enter image description here](https://i.stack.imgur.com/W57LY.jpg)](https://i.stack.imgur.com/W57LY.jpg) In this map, the observer is looking towards the east, making the north poles of both planets off towards the left. I figure, from this particular vantage point, the observer can see about 25% to 30% of the twin planet. Since they're tidally locked with respect to one another, that aspect of the sky never changes. # The Question! Given that Camay would be more visible* the farther east I travel from Pycleas, because I'm moving towards the line in space where the twin planet's cores line up; about how far west can I go before Camay disappears entirely? Pertinents: Yeola is 34,851 mi in circumference (11,093 mi in diametre); Camay is 33,124 mi in circ. (10,543 mi diametre); the distance between their poles is 2.6 planetary diameters or about 28,128 mi. (NB: if that makes Camay "look too big" in the sky, then I may opt to place them further apart.) --- To make life easier, while there are mountains (none terribly high) and hills and valleys and forests and so forth between Point no. 1 and Point no. 2, we can probably sweep those differences in elevation under the most convenient of metaphorical rugs. I'm looking for a broad range (say within 50 or a hundred miles) rather than a definitive point, brought out to fourteen decimal places. Also, you can ignore that their miles and our miles are slightly different in length. --- The very allerbestest of responses would couple visuals with numbers. A merely acceptable response will simply state a rough distance (in miles) west of Pycleas where the twin planet disappears. [Answer] I'm amazed at the amount of detail here, but most of it is really not necessary. We only need to know 3 things: * The diameters of the planets * The distance between the planets * Which point on Yeola is closest to Camay To elaborate on the last bullet, we need the point that lies on the axis connecting the two cores, like you mentioned. I'll call this point P. You'll need to find P for yourself because it's not clear from your maps where it is exactly (though you mentioned it was east of Pycleas, so presumably you have some idea). I'll take your answer of 11093 miles as the diameter of both planets from your comment. Having the same diameter means that the answer to "where on Yeola can you see Camay" becomes really easy. Simply divide Yeola into hemispheres, with one of the hemispheres centered at P. If you're in the hemisphere that contains P, you can see Camay. If you're not, you can't (Camay will be below the horizon). Easy as that! For a more detailed answer that includes how large in the sky Camay is at every point, we need to know how far apart the two planets are, and how they rotate around each other. All of this information is in your skymap. Camay is (nearly) exactly in the eastern part of the sky, which seems to me can only happen if they orbit around each other in the same plane as their equators. On Earth, we defined north and south as the directions toward our pole of rotation. It seems logical to me (and supported by the evidence of the skymap) that the people of Yeola did the same. Since Yeola and Camay are tidally-locked, Yeola's rotation axis is parallel to the rotation of Camay around it, so I think I'm safe to assume that Camay and Yeola orbit in the plane of each other's equators. That simplifies things a lot, too. So how far away is Camay? If the skymap is accurate, ~19353 mi away. To see why, look at the diagram below. [![enter image description here](https://i.stack.imgur.com/22CNH.png)](https://i.stack.imgur.com/22CNH.png) The skymap indicates that Camay takes up $0.1913 \pi$ radians of the sky (I measured the pixels N-S). We know that its cross-section on the sky is roughly its diameter, 11093 miles, so $11093/ (0.1913 \pi) = d = 18458$ miles. Next, we'll use the fact that 55% of Camay's diameter is visible above the horizon at Pycleas (you mentioned 25-30% of the surface was visible, or about 50-60% of the hemisphere facing Yeola). A bunch of annoying similar triangles later, we find that $D = \sqrt{2(0.55)R^2+d^2} = 19353$ miles. Which is to say that these planets are frighteningly close to each other. There's a little less than one planet width between the two of them. This will be true as long as the skymap is accurate, even if you eventually change the scales of the planets (at present they're about 40% wider than Earth). But fair enough, let's actually use this to calculate the size of Camay in the sky as a function of your angle away from P, which we'll call $\theta$. How do you find $\theta$? Well, if you're directly north or south of P, $\theta$ is just your latitude (N or S), and if you're directly east or west of P, it's the difference between your longitude and that of P. If you're at a different position, you can find it by simply calculating the distance to P along the surface, then dividing by Yeola's radius (this answer is in radians, so multiply by $180/\pi$ afterward to convert to degrees). Anyway, the angular size $S$, in degrees, of Camay for any theta is $S = \frac{360}{\pi}[(\frac{D}{R})^2-2\frac{D}{R}cos\theta+1]^{-1/2}$, where the ratio $\frac{D}{R} = 3.489$. Important angles: * At P, which corresponds to $\theta = 0$, Camay is right in the middle of the sky all the time. Its apparent size is a whopping 46.0 degrees wide, nearly as big as a steering wheel looks when you're driving. For comparison, the moon as seen from Earth is half a degree. If I lived on Yeola, I would be looking up, awe-inspired, like, all the time. * At $\theta = arccos(2R/D) = 55.0$ degrees, Camay touches the horizon. At all angles between this and 90 degrees, Camay will be partially hidden behind the curve of Yeola. Here, Camay is 37.8 degrees wide, like a basketball held at arm's length. * At $\theta = arccos(R/D) = 73.4$ degrees, Camay is halway below the horizon, and looks like a semicircle. Based on your view of the sea from Pycleas, its $\theta$ value is a little below this. $S$ is 34.3 degrees here, so just a bit smaller than the previous bullet. * At $\theta = 90$ degrees, Camay disappears just barely below the horizon, but you can see it if you stand on a tall ladder or a mountain or something. It's 31.6 degrees wide here, about the size of a soccer ball at arms' length. Here's a handy reference (pun definitely intended) if you want to be able to picture how large in the sky it is. ([Source](https://en.wikipedia.org/wiki/Angular_diameter)) [![enter image description here](https://i.stack.imgur.com/itdnG.png)](https://i.stack.imgur.com/itdnG.png) Just hold out your hand at arm's length, and these gestures show about how big these angular sizes look. ANSWERING THE QUESTION I have enough information to calculate where P is without you telling me, and thus give you an exact answer, but I'm not sure how valid it is to assume that Camay in the star map is perfectly sized. Regardless, I think this answer is close, and certainly $\theta$ for Pycleas is roughly 70 degrees, since this is required in order to have Camay near the horizon as seen from there. By adding this ~70 degree angle to Pycleas' longitude, subtracting a bit to account for it being 24 degrees north of the equator, I would place P on the equator at around 90 degrees E. Conveniently, that means that Camay disappears right at the prime meridian, so it's even easier to tell when you can see it: if you're in the eastern hemisphere, you can see it. If you're in the western hemisphere, you can't. Thus, you stop seeing Camay when you cross into the western hemisphere, ~36 degrees (~3,500 miles) west of Pycleas. [Answer] Trace a circle around your globe that passes through both poles. Make the plane of this circle be perpendicular to the line between the cores of Yeola and Camay. This circle splits the world in to hemispheres. On the one closest to Camay, Camay is visible. On the farside of the world, Camay is never visible. Given a circumferance of Yeola, the distances would be simple formulas. Calculating the circumferance given the information you've provided is likely doable, but I am unable to do so at this time. ]
[Question] [ In the movie Captain Marvel, the main antagonists (at least for half the movie), the shape-shifting Skrulls, can change their appearance to perfectly match any humanoid creature, down to DNA. Scientifically, I would label this as just conscious and very fast evolution, but they also replicate the DNA of the creature perfectly, without further study of it. Can this be achieved, at least in a lab? [Answer] # No. You can deduce certain things about a person from their physical appearance, hair colour, skin colour, eye colour - will all give you clues to certain genetic markers that they will carry. You can perform every physiometric and psychometric test on a person at our disposal, and make a number of deductions. You can have the complete paternal and maternal DNA profile on record including the mitochondrial DNA. None of this gives any certainty as to the genotype of the individual/offspring. The phenotype (expressed genes) is not even entirely dependant on the genotype (total genes - used or not), because of epigenetics (some genes have a chemical group attached which prevents them from working and thus hides them from observation). This is much less than half the story: Between 85% and 92% of DNA is [non coding](https://en.wikipedia.org/wiki/Non-coding_DNA). That is, it's junk, it doesn't do anything and therefore has no observable effect that could be used to infer it's presence - but it's still there measurable to a DNA test. # Edit: I suddenly realised that I answered the question for humans. The question asks about humanoids. It's incumbent on the OP (the author of the world in which a story takes place) to decide the rules there. There their humanoids may have a different genetic history, may have had the junk DNA removed to streamline the code. Genes and epigenetics might be standardised, a whole society could be of a limited number of genotypes - all clones - all down to the author's choice. [Answer] I don't remember which book, but one of Richard Dawkins' books makes a point that is relevant to this question: Often DNA is described as the blueprint for an organism. However, that's a bad analogy: DNA is much better described as the recipe for an organism. By looking at a completed building, you can probably re-draw the original blueprints with reasonable accuracy. But by looking at a completed meal, you will have a lot more trouble accurately listing back out the original quantity of every ingredient and the steps to transform them into the finished product. As a shape-shifter, a Skrull could certainly replicate the outer appearance and characteristics of what they see in another organism, but replicating the DNA based on observation would be out of the question. If for no other reason than multiple different "recipes" could, conceivably, result in the same result. How would the Skrull pick the right one just by looking at a person? (Although looking back at your question, I realize you didn't limit to just visual macro observation, but I haven't seen the movies so I don't know how much observation the Skrull need before shape-shifting.) ]
[Question] [ Magic in this world focuses on controlling the elements of nature (earth, air, fire, water). Witches perform magic by drawing in energy from the natural world and focusing it into a spell using their own mana reserves through an incantation. In this way, they are able to channel this energy into affecting the material world. Using witchcraft for warfare is limited, as there are not many witches. Therefore, they are a valuable addition to any army. The problem is limiting their effectiveness. Throwing fireballs, calling down lighting, or causing earthquakes are far too powerful, and turn these witches into one-man armies. The amount of energy in the environment is unlimited. However, powerful, attacks like those would take a massive amount of time, energy, and quantity which are usually impractical. Those nuclear options would take large amounts of witches several hours to complete, spending high amounts of their own mana in the process, which is why they are rarely used and saved for extreme measures. How can I limit/balance my magic system to force witches to play a necessary but limited role. The best answer will: * Discourage direct, frontal combat. * Encourage ambush and surprise-related tactics. * Express the limitation in terms of the elements of nature. In other words, "if they draw more than X mana, it'll burn them up" isn't the kind of answer I'm looking for. [Answer] Your system is already well setup for those tactics: to defeat an army you need a large group of witches to spend hours preparing an obvious and tiring spell, but to defeat those witches all you need is a single witch to break their concentration for a second. The only requirement is an obvious sign that a big spell is being caused so that opposing mages can disrupt it. If storm clouds start gathering or trees start growing in a specific area, it's a guarantee that an army's witch-artillery ([howitchers](https://en.wikipedia.org/wiki/Howitzer)?) will zero in on the witches preparing the spell. These watchful witches will finish their small spells first, sending focused lightning bolts and fireballs to ruin runes, halt hymns, and cutoff concentration long enough to cause the big spell to fizzle. Because of this, magical strike teams using small and quick spells will be the main tactic of witch warfare. Disrupting enemy supply lines, striking vital infrastructure, assassinating critical targets, and stopping attempts to cast big spells will be the main tasks witches perform, as well as staying on reserve to prevent such attacks on their own logistics network. Neither side would risk sending their witches into the main fight, in fear that doing so will weaken or distract them and allow the enemy witches to finish a big spell. [Answer] # Controlling wood * Shafts of arrows swell with water (the witches manipulate the water already inside the cells). This makes it difficult to shoot them and impossible to aim properly. * Wooden bows also warp and weaken as the water in them changes. * The heads of axes fall off their wooden handles. Ditto any weapon using a wooden handle or pole. # Controlling metal * Sword hilts heat up with fire. No need to affect the entire sword, just the part the hand touches. A glove thick enough to protect the hand would also affect how the solider fights. * Knives (whether for fighting or throwing) have the same problem. * Armor becomes too hot to wear. * Helms discharge water through the eye holds, making it impossible for the solider to see when they're on. # Controlling wind * Ground glass is carefully blown and aimed into solider's eyes and up their nostrils. * Or stinging ants. * Or stinging nettles. * Or even nothing more than thick campfire smoke. It follows the soldiers around and does not dissipate. * Has the advantage of it not being as obvious that magic is involved, if you wish to hide that fact. # Controlling earth * The ground appears even but random locations have tunnels (think something like gopher holes) that you don't know are there until you step on them and your foot sinks. Or twists. This takes care of mounted soldiers and reduces the number who can get through on foot (or limits their speed). * Stepping on invisible fire ant or yellowjacket nests would be a nice touch. There are many ways your witches can use minimal energy to devise attacks on their opponents. None of this kills the soldiers outright but it makes their weapons less useful and makes them vulnerable to traditional modes of warfare from the soldiers the witches are helping. [Answer] Every elemental force could be hampered by its enemy force (for instance water vs fire, earth vs air... or - even better - a scissor-paper-stone scenario, like water beats fire beats earth beats air...). This way you can limit the power of the spells a witch could launch. For instance, a fire witch would become less powerful according to the quantity of water nearby. If she must fight near a river or the sea, her fire spells could deal a little more damage than a sunburn. An earth witch would be extremely powerful in a cave, but would lose a big amount of her power on the top of a mountain. Battle tactics could rely on this information: if I know that my enemy has a water witch at his disposal, I could turn on big fires to reduce her impact on the battle; or I could pump a lot of fresh air in a cave to face an earth witch, and so on. [Answer] I made a custom tabletop RPG with Ad Hoc magic like this once, and my approach worked out fairly well. To start, think of the power a witch can project as limited the same way your body is limited, and try to keep it someone "human" in scale. A Human body can lift ~10-300kg or run ~15-45kph with most people in the far lower limits. Just like you can limit and measure how much a person can exert their body in things like speed and strength, a witch just needs a measure of their limits as well. Secondly, you need to limit things that give you a perminate pay-off for a one time investment or give too much power over elements outside of your domain based on technicalities such as being able to make a giant army of stone golems by bringing them to life or using the heat in a rock to activate a fire power. For example, an average hydromancer might be able to do the following: * Exert a force of 100-3000 newtons on any body of water at a time depending on their proficiency with most being in the 150-300 newton range. * Cause 5-100kg/sec of water to phase shift between solid/liquid/gas depending on their proficiency with most being in the 10kg/sec range. * Can extract water from solutions at a rate of 0.5-5 liters per minute depending on their proficiency with most being in the 1 liter range. + Can not use other powers directly on water solutions that are more less than 95% water From these rules, most witches could derive the following abilities: * Walk on water * Use a bucket of water to quickly freeze a door shut. * Use a bucket of water to quickly fill a room with steam. * Convert a cup of water into lethal javelin of ice. * Damn up a small stream with a wall of ice over the course of a few minutes. * Extract drinkable water from mud. * Slowly and painfully kill a person by pulling the water out of their body. * Use salt water, wine, or other >95% water solutions as "water". A powerful witch could do some slightly more impressive stuff like: * Launch a cluster of deadly ice sicles, killing a small group of enemies with a single attack. * Quickly form an icewall blocking a corridor * Pull enough water out of a person's body to kill them in seconds. Things that a witch could not do alone (or not at all) include: * Freezing an entire army's feet into a bog. * Summoning a blizzard to bury a city in snow. * Parting the Red Sea. * Instantly freeze the hearts of a group of enemies. * Bring a body of water to life * Use blood, mud, or other <95% water solutions as "water". [Answer] Witchcraft thwarts and poisons. Traditionally, witches are suspected when milk goes sour, lambs aren't born, babies get sick, wheels fall off. Witches mess up what you are trying to do. The problem is you are never sure if it is witches, or if it is just bad luck. Or both. This stealthy endeavor is perfect for your witches. Bowstrings and axles break. Food goes maggoty. Blisters form. Holes open in your pockets and pouches. Bad teeth act up. Bedbugs come. Nothing impossible. Nothing that might not happen normally to an army in the field. But when you find a two headed albino toad floating in the beer, that is her signature. That is when morale starts to crumble. Because maybe the toad is all she actually did, and the soldiers give her credit for everything else that goes wrong. [Answer] I think that some smaller spells would help with this. The witches don't need to call lightning, but they could be able to send small electric discharges strong enough to do damage. Maybe they can be able to manipulate water, but not a lot of it. Trow not so big fireballs? But I think potions would be really useful. There can be potions that blow up like grenades, potions that unleashes a stunning gas, etc. [Answer] Environmental Weaponry Whilst creating earthquakes or summoning lighting may be too energy consuming, we can instead use nature to our advantage. Rather than creating an earthquake, it is far easier to engineer a landslide. Your witch would stand at the top of a canyon, mountain passage, hillside, cliff, etc. When the enemy army approached, she would use her magic to push dirt or rocks or even snow onto them or in front of them to block their path. You could even have two witches, one to block their way forward and another to block their retreat, trapping them in the middle. From there archers can fire down onto the army trapped army to kill them. In a similar sense, you could have witches create floods by bursting dams or riverbanks, causing the water from a reservoir to flood the valley or the river downstream, thus drowning and battering the enemy. Air can easily be utilised for an ambush. By pushing loose material, such as dirt or sand, into the enemy army you have effectively blinded them. The small particles will go into the solider’s eyes, causing them to water and be extremely uncomfortable. This allows your own soldiers to run in and kill them as they won’t be able to properly defend themselves. Fire is by far the easiest element to use as it spreads on its own. This means you do not need a huge amount of it to achieve a devastating effect. When the army marches through a dried grassland or forrest, your witch can create small fires around them. The dried land will quickly ignite and spread, eventually engulfing the army in flames. Human-Made Weaponry All of the above depend on the local environment, you cant create a flood without a large body of water, nor can you create a landslide without somewhere to push the material down. These methods can be more easily employed in a variety of places. While you may be hard pressed to find a mountain to create a landslide on in a city or village, this does not mean you can’t employ other methods. Rather than pushing rocks down hills, you can instead collapse walls and buildings by damaging the load-bearing walls. This achieves the same effect as described above, just in settlement. Water is hard to use if there is no natural body. However, it is not impossible. You can bring water and heat it to create steam, using it to obscure your army’s movements. Quite a valuable tool in some cases. Air is also hard to utilise, though you could potentially use it to create updrafts, allowing you to use gliders to scout out the enemy or drop troops behind their lines to sabotage equipment. Finally, we come to fire. Fire is again the easiest to use, enemy siege equipment or tents can be set alight, killing or weakening their forces. You could instead use it to create smoke, obscuring your army’s movements. Here are some ways your witches can utilise their magic in an ambush-like way. Some of the above may instead fall into sabotage or skirmishing but i feel like that is what you were going for. None of these methods would require a huge amount of energy as most are using the already existing energy found in nature, such as gravitational potential or chemical energy. This allows for witches who’s magic is not exceptionally powerful to be very useful in some situations. [Answer] Discourage direct, frontal combat. - Snipers. Magic might be great but having your head explode before you even hear the bang puts a real damper on it. Witches would dress as regular soldiers and try to blend in. Throwing a fireball might be cool but it points you out to a sniper. Encourage ambush and surprise-related tactics. - Magic counters magic. If they know you're bringing magic to the fight, they bring magic to counter your magic. It's most effective when they don't know it's coming. A witch would be an awesome multi functional commando. They can scout, mislead, communicate, heal and fight all rolled into a single air droppable soldier. Express the limitation in terms of the elements of nature. - Each witch has a garden hose worth of magic. Sure you can fill a lake but it will take a really long time. Two witches do it twice as fast but still a long time to fill a lake. A huge coven of witches working together and suddenly that lake is viable. A huge coven can do powerful things but another huge coven can drain the magic back out just as fast as the first draws it in countering it's effectiveness. Even a smaller coven can slow the ritual down enough allowing time to evacuate, counter attack or bring in reinforcements. ]
[Question] [ In [an interesting question here](https://worldbuilding.stackexchange.com/questions/53836), @Masclins asks how two twins who can each experience and perceive everything the other is sensing or thinking might be able to exploit their ability. I want to ask a question where the psychic ability is much more limited in some respects but is precognitive. Imagine that a single person has by a great deal of application developed the skill of sometimes being able to send himself a small amount of information back from a short time in the future. By a "small amount of information", I mean on average less than a single [bit](https://en.wikipedia.org/wiki/Bit). So if in the future he chooses a playing card at random - perhaps using a quantum random number generator - and then looks at it, he can with a slightly greater than evens chance predict correctly right now whether the card will be red or black. Similarly if without telling our subject an assistant decides that red corresponds to an appreciation of the British pound against the Swiss franc and black to a depreciation, and at a future time he checks how the currency market has moved and then gives the subject a card to look at accordingly, the subject can predict its colour with a similar chance of success. If he could always predict the card colour correctly he would be sending a whole bit of information, but by "sometimes" I mean he can only do it correctly 53% of the time1, and moreover he can only manage to repeat the precognition, even at that level of success, at least a week after the last time he did it. And by a "short time in the future" I mean no more than 30 seconds. To restrict the conditions even more, let us assume our subject does not have access to a vast quantity of money. So for example he cannot invest a million pounds each week selling or buying Swiss francs for British pounds according to the card colour he perceives precognitively. Nor can he offer his services to a person who can stake large amounts. How might he use his precognitive ability to amass wealth? Edit: please note that this question is not the same or even nearly the same as [this other one](https://worldbuilding.stackexchange.com/questions/141820). The ability I am supposing is probabilistic. There is no possibility of chaining perceptions together as is suggested in the most popular answer to that question, because the ability only works (probabilistically) 30 seconds into the person's own future and only at intervals of at least a week. The second most popular answer is also not applicable, since again the ability works probabilistically with a success rate of only 53% and the person does not have access to big money. Basically his edge is very small, this is clear in the question, and it is signalled in the word "slight" in the title. 1 Technically the average number of bits of information he sends per prediction is 0.00260, so he would have to do it 385 times to send a single bit. For details of how to calculate that figure, click [here](https://stats.stackexchange.com/questions/399102). The point is that the ability is not only probabilistic but very weak. But it is no less real for that. [Answer] Suppose you're playing roulette and betting on red or black. Your ability is equivalent to saying that for every 32 spins, you get a "freebie". (Or equivalently, for a large number of spins, you will grow your total stake by 6%). But the house gets a "freebie" for every 36 spins, because no one wins on zero (and in American roulette, which also has a double zero, the house gets a freebie for every 18 spins) – so your actual gain is either 3% or 0.4%. And given that you can only play once a week, "a large number of spins" is going to take at least a year. You would likely get a better return, for no effort, by investing your money conventionally. The same principle will apply to any other game. Because your ability is barely better than flipping a coin, it takes a lot of bets to manifest its advantage. And any repeatable bet is not going to pay better than evens on a 50/50 outcome (if such a bet existed, you wouldn't need precognition to get rich). Plus, there's always going to be a house advantage. Even without the recharge time, this ability would not be a life-changer. Reward generally corresponds to risk, and if something is too risky for a normal person, it will almost always be too risky for you, too. (On evolutionary time scales, though, it would be a significant advantage) [Answer] # By-passing the 53% It seems the message needs to be sent - a conscious action - and whether the content is correctly received is governed by this 53% statistic. If, instead, you look for a binary 'yes/no was a message there to be received?' and only send a message if past you should act then we have three options. * Message recieved and action rightly taken. * Message not received and not act even though you wanted to. * No message sent so no action taken, as intended. So if you're deciding whether to place money on something you'll never lose. The obvious go to answer: # Gambling There are plenty of options in casinos but roulette is probably the game with the best odds (32x return on single numbers). In a casino, however, you might want to throw a few games else you'll draw suspicion. Online is better as it is impossible to cheat by traditional means so it is unlikely you'll be caught out. You can also play on several different sites at the same time this way. # Stocks Algorithms giving traders split second advantages sell for millions - if a split second is worth that then if you learn about stocks you'll be able to cash in on a 30 second advantage. # Invest and repeat Your foresight may give you some advantage here but also an element of business savy will help - you can set up your own businesses with the money you've made and ensure a steady income. [Answer] We have a matured precognitive ability already called imagination. It functions to produce possible futures based off the current universe and prior experience. 99.9999% of these imagined futures are wrong. Occasionally an individual manages to imagine a future that is less wrong, possibly even correct. This gives that individual time in which to prepare, which confers a survival advantage if that preparation can be leveraged to overcome the problem that is there in the present when the future arrives - regardless of the imagination's accuracy. The important point here is that something as imprecise as imagination offers survival benefits. The precognitive ability you suggest is an improvement to imagination, significantly improving its accuracy. This will not improve the individuals ability to guess a needle in the haystack, that problem requires way to much accuracy. However if you rephrase the problem as one of locating food we can see the benefits. Lets assume the individual will find food regardless of their precog abilities. The question is: in a competition to find the best food, would an occasional 30second lead allow them to obtain the most nutritional food before their competition does? The answer would be yes, very useful. More nutritional food, more often than the competition, allows more time to be directed into other activities, or finding even better food. This is a small advantage in terms of energy. But Humans walk on two legs because it is slightly more efficient when walking through plains then walking on four legs like our ancestors. The energy efficiency is very small over a lifetime, upright walking saves the energy you get by eating about a packet or two of chocolate biscuits. So having a precog ability that improves energy efficiency/acquisition by similar numbers is entirely reasonable. Added up overtime such individuals would be more likely to have forged better relationships, more likely to have accumulated resources, and by equal measure the competition will have not had the time to forge relationships, and not have as many resources. This doesn't mean that any given individual will certainly do better, just that those with the precog ability will be more likely to have done better. Stupid mistakes will send them back to zero just like anyone else. ]
[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/141351/edit). Closed 4 years ago. [Improve this question](/posts/141351/edit) The most impressive thing to me about how werewolves are used in fiction, is their ability to transform humans into other werewolves with their bites. Aside from the full moon myth, could it be potentially possible for an organism to 'infect' another organism and 'override' or 'corrupt' their physiology and essentially turn it into another? Are there instances of this happening in any way? [Answer] If you take a look at [Rabies](https://en.wikipedia.org/wiki/Rabies#Signs_and_symptoms), you can already see a lot of parallels between the symptoms of it and vampire / werewolf mythology. There's an argument that this is the historical basis of some of the mythology in any event. The problem with Rabies as the vector for transformation in this scenario is also its strength; it attacks the brain, causing massive changes in personality that are actually designed to spread the virus. While that's good for what you're proposing, it's also bad because it eventually kills the host. But, for the sake of argument... Imagine a modified rabies virus that still has the neurological damage but has a timer set on it; it only does neural damage for a specific period of time then stops, or lets the body's natural immune system overwhelm it, but only in the brain. In that scenario, you have a human or other animal changed (although not into a different species, just something barely recogniseable as human anymore) but is still capable of survival, albeit with the drive to bite and spread the virus according to the original programming. This modified rabies virus, particularly if it starts introducing physical changes to a person after it abandons the brain, would give you all the appearance of a werewolf style disease, spread by bite, without genetic transformation. [Answer] Some living things have evolved ways to [co-op other creatures](http://www.cracked.com/article_19384_the-5-creepiest-ways-animals-have-mastered-mind-control.html) and force them into doing their bidding. There are species of wasps that lays eggs into other creatures like spiders and caterpillars. These eggs hatch into larvae which not only eat their host from the inside out, but also infect the hosts brain and manipulate it. There is a fungus who spores can infect ants. Once infected, these ants are consumed by the fungus, and then are manipulated into relocating to a suitable spot for the fungus to leave the ant and continue growing. Parasites called [hairworms can infect crickets](https://news.nationalgeographic.com/news/2014/10/141031-zombies-parasites-animals-science-halloween/). Once the hairworms infect the crickets they release chemicals that cause said crickets to move toward sources of light. This is done because hairworms need water to reproduce, and water reflects moonlight. The infected crickets haphazardly jump into bodies of water allowing the hairworms to emerge and reproduce. P.S. There is an condition called [Hypertrichosis](https://en.wikipedia.org/wiki/Hypertrichosis) that causes a werewolf like appearance. ]
[Question] [ I am curious as to what physical geographic features would be present on a plateau 10km above sea level. The Tibetan plateau is only 4km above sea level, so would more than doubling the height exaggerate the geographic features we already see in Tibet, or would new and strange climates and temperature start to form? [Answer] 10km is waaaaaaay too high. On your world-building dashboard you have taken one of the dials, thought about turning it up to 11, and instead turned it up to 48. But it is an interesting experiment to think about: what are the physical effects here? * Too heavy for the crust/mantle to support: The Himalaya and tibetan plateau are the biggest features Earth can support. Their height is facilitated by continental collision that can push up the thickened crust against the HUGE desire to sink down into the mantle like an icecube bobbing in a glass of water. You need a fundamentally different kind of tectonics to support this kind of feature, meaning a planet that is either old or small, such that it has cooled off and has a thick elastic crust atop the viscous mantle (eg. Mars). * VERY COLD: The atmosphere is, on average, 6.5K colder per Km elevation. So you are 65 Kelvin colder than sea-level on that plateau. * Not even normal atmosphere: 10km is near a point we call the tropopause, meaning the atmosphere is so thin that its temperature is no longer kept in a normal thermal distribution by collisional dynamics, and is instead radiatively-dominated. That doesn't actually affect much if you're living in it -- just feels like cold, thin air -- but I want to highlight HOW thin and cold that air is. * Messes up global winds: 10km wall? I can't even picture what than plateau does to airflow. Blocking global air circulation with an insane Rossby wave on the leeward wide? huge hurricane force gusts as air descends off the edge of the plateau? Some continual push of air to the outer edge of the plateau? Very disruptive to the global system. [Answer] [According to this source](https://www.cwb.gov.tw/V7e/knowledge/encyclopedia/me006.htm), the climate up there would be extremly harsh, at temperatures around -35°C with strong winds. Because of the thin air in these heights, those may won't feel as strong as at ground level. Nothing would be able to survive in such heights, as this is even worse than the arctic climate. ]
[Question] [ A world idea I'm playing with for a sci-fi idea I'm working on has an atmosphere similar to the composition of Earth's atmosphere during the Carboniferous Period: [Lots of oxygen, so while a human or a creature with similar breathing needs could probably breathe fine, that also means everything is extremely flammable.](https://io9.gizmodo.com/the-one-basic-fact-about-history-that-time-travelers-al-1652649190) As this world is also relatively similar to Carboniferous Earth in that a large percentage of its overall landmass is covered in fairly dense forests, and while it's fairly damp and even downright swampy in many of these places, the higher oxygen content means that even damp things can sometimes Ignite. The major sapient species on this world, as a result, are obviously fairly wary of fire hazards and fire in general; as a result, contrary to the evolution of technological progression in humans (which most sources say began in earnest with early man learning to harness fire), they likely wouldn't be able to harness and utilize Fire safely until much later in their civilization's development, when they would have the means to contain it and prevent its spread on a large scale. Even then, if they developed a means of harnessing fire at all after so long without it, it would probably be used sparingly and Very Carefully, limiting or at least slowing experimentation. I have worked out a potential alternative: natural hot springs and other geothermal activity can be used in things like cooking and other complex food preparation, and the steam could probably be funneled or channeled to heat dwellings and power relatively simple machines, which in turn could probably open up new options for developing other technologies. They also behave and structure themselves in a fashion similar to an ant colony, and as a result already practice various forms of agriculture (similar to the practice of many in-real-life ant species that cultivate edible fungus and raise/"pasture" aphids for both nutrient-rich secretions and, eventually, meat) that would likely be aided by, and be an evolutionary pressure in favor of, the development of tools. The one dilemma I have is this: while they can compensate for/find different paths to the development of various other technologies that seem to have shaped the development of human civilization, their aversion to/difficulty working with fire is going to make things like metallurgy difficult. While they were not initially a space-faring race, and only became aware of interplanetary travel when briefly invaded and occupied by a military power from another world before fighting them off and regaining independence later, they have likely seen the benefit of joining the intergalactic community on their own terms and are going to try and turn their hand to creating spacecraft, which will likely involve manufacturing things like metal and glass and plastic components (or, you know, rough equivalents) on a large scale. While it's possible that they borrowed new technology and ideas from their former oppressors, I was wondering how far along they could get in terms of Smelting Technology without outside influence, and how big of a jump that's going to be for them to make. So, my question is this: if they have some means of funneling and redistributing steam for things like heating their nests and warming water (probably by digging tunnels or boring out large tree trunks for makeshift piping), could they somehow... Collect that heat, and use it to heat up something akin to a kiln or forge in function? Or is this something that, as far as we know, can only be accomplished with fire? Alternatively, what methods could be used to control the spread of fire enough to allow them a little more experimentation, given the higher amount of oxygen and increased likelihood and danger of accidental fire-starting? [Answer] In our history, getting metal up to heat was a big problem; so, we used billows to force extra air into a burning fuel source (coal/wood/etc.) In their version, they could mostly seal off the the fuel and only let air in through a valve that can be opened and shut. The more sealed off your fuel is, the better you can trap the heat for melting your ore. In many ways, metallurgy would be at least as easy, if not easier for them to figure out as it is for us. [Answer] Apart from the temperature the others mentioned there is another problem: You NEED coal (or other carbons) to create steel from iron. From Wikipedia: "Steel is an alloy of iron and carbon, and sometimes other elements" So even if they can create the heat to run a kiln or forge they can't make steel without coal. Of course they can make charcoal from the trees but that also requires fire. They probably can make stuff like Bronze and Aluminum, the question is if that is enough for you. What I would try if I was REALLY scared of fire: Build your forge in a cave with a (maybe artificial) waterfall in front of the opening to the cave. [Answer] The biggest impediment to metalworking without fire is getting the metal to [forging temperature](https://en.wikipedia.org/wiki/Forging_temperature). Even the easiest to work metals, such as lead and tin, require temperatures around 300 C and 200 C respectively. These temperatures can be attained in a campfire, but geothermal steam of that temperature is pressurised and dangerous. The truth is that without fire, your species will not achieve metallurgy. ]
[Question] [ I am in the process of fleshing out an alternate world where, following an unnatural super-storm (think cold snaps down to -30°C and heavy snowfall in the 4ft range [1.2 m] inside of 8 hours) in the middle of June, a large number of people are cut-off in the Cold Zone. This zone reaches to the Northern end of Kansas, USA, while its origin point is centered over Hudson Bay in Canada. The event takes place during high tourist season and as a result a lot of people unfamiliar with the cold northern winter climate will be present. The return of magic is occurring but is not immediately obvious. The unnatural winter is being caused by a magical tear leading to a hellish world of ice and snow. Due to the weakening of the fabric between our world and other worlds bordering it, various entities, structures, and monsters begin to appear in the Cold Zone. Especially during blizzards and other periods of extremely heavy snowfall. I need a plausible way for this creature in particular to go largely unnoticed for 2-3 weeks. Monster I Need Help Hiding Snow Kraken: These great monstrosities are made up of snow and ice bound together into a semi-rigid shape anchored by runes lining its solid skull and the solid bases of its 10 tentacles which branch out from it. They are around the size of a school bus typically, but like an octopus can squeeze their body and compress themselves very easily. They hunt by feeling/hearing tremors through the ground as well as eyesight when peeking above-ground. They burrow through the frozen turf at roughly 15mph [24 km/h], but cannot burrow through solid stone and rarely go deeper than 40ft underground [12 m]. Fear fire and are usually encountered in dense forests and open plains. Although at least one has climbed up a mountainside so it could create avalanches and ride the waves of snow down. They can regrow tentacles if they lose one, but it requires them to have a source of ice and snow as well as 2-4 days. Their rigid skull and tentacle bases are only the size of a smart car with ten golf club bag sized bases bristling off the back end around the creepily human-like mouth. It can contract its skeletal structure to roughly 1/4 the presented size here. So where could it hide in a modern world wracked by super blizzards where 4-6ft [1.2-1.8 m] of snow falls each day? [Answer] It's really cold outside with mountains of snow! All those tourists are huddled indoors. Even if they were familiar with Northern winters, they didn't bring clothes for them. Especially not shoes you can wear outside in those conditions without getting frostbite. Only a few locals, who have the gear and the vehicles, are venturing out to find food and wood/fuel for everyone. Or in some cases, taking tourists down south. No one is going to go out on the lake, which is where the tear between the worlds happened. The monsters have come through there, steady for now on the solid ice the lake has become. Like humans, the monsters will venture out for food and supplies. Or plain old curiosity. They are probably worried and scared because they have been transported to a place they don't recognize. When they see humans, they'll stay away. The supernatural element is obvious from the weather. But occasionally a monster will be in a position where a human can see it. Maybe from very far away, maybe in the dark, maybe even a full on encounter. Will the other humans believe the one who saw the monster? At first, no way. But as the stories pile up like the snow around them, they start to wonder. Eventually, they're convinced something horrible is happening. Having this process take a few weeks works well. This will also be the time period when the humans have depleted the food and wood available to them within a few miles. If the roads are open to cars and the cars all work, everyone would have evacuated after the first few days. If they're around it's because they're stuck there to serve your story. Or perhaps most evacuated and a few stayed behind and they're the ones experiencing the monsters (and stuck because now the roads are impassible). Even if there is electricity and communication with the outside world, there may be no way to get to them. What happens next is up to you. [Answer] They can cloak but only for a number of hours or perhaps they camouflage with the snow. Perhaps the supernatural beings use their magical abilities but because magic is still returning, they cannot utilise their full powers yet - there is not enough "mana." People eventually realise this because they inadvertently begin to harness magical powers too... and tap into their five senses in ways they couldn't before. Interesting premise, keep it up! [Answer] So for the most people if they actually survive seeing your example Creatures they will think the cold either destroyed their brain and they have gone crazy or think that the cold has caused them selves to see things that aren't there. Also when anyone will witness something strange from some of your creatures rather than investigate most people will flee. So those who actually investigate are most likely alone or in a small group up to three. With the size of these groups most creatures you mentioned will easily deal with them and if one escapes nobody will really believe them and instead believe the cold caused them to get crazy or another normal wild animal killed the other people from the group. Of course when these accounts of survivors increase and when considering the abnormal weather at some point people will get behind it but this will probably take months or even a year (when the cold stayed for all four seasons) but even then Governments and other institutions will rather tell lives in order to keep stability instead of admitting that they have no clue whats going on. [Answer] The rift isnt instantly passable. At first the monsters appear for a short moment (say an hour) then are gone again. Even if they leave trails or are seen their sudden disappearance will make people doubt themselves but still que them that something strange is happening. From "burglaries" where a monster appeared in a house (usually empty during the day) and wrecked stuff to grisly murders with survivors not being believed by the wider public (the local detective who sees the bodies and some camera footage will probably believe). Segregation due to the weather and intermittend communication with the rest of the world make it hard to know what's real or not until the monsters manage to be permanent and start a rampage within city limits. ]
[Question] [ So I have a race of shapeshifters in my world, and in order to change shape or make adjustments to their body (grow wings, arms, tails etc.) They rearrange the atoms in their body, probably through magical means. Greater changes require more energy to move the atoms around, and can also be rather painful, meaning that a shapeshifter could potentially die if they exert themselves too much. Would this method of shapeshifting have any serious effects on the health or inner workings of the species, especially considering that they nearly constantly change around the particles in their body? Edit: If you don't spot any issues with it you can let me know as well! [Answer] Yes, there are some serious issues with this over the long term because of the internal structures required to support the external ones. First of all, the examples you've given all involve 'growing' a new appendage of some kind, meaning that you either; 1) Increase the mass of the individual quickly, or 2) Decrease the size of the individual proportionally to cover the mass going to the new appendage In the first case, you've got to eat a lot, just to deliver the mass increase that you need. This means that the bulk of your abdominal organs are off limits during the change because they're actively delivering mass and energy for your new body's needs. In the second case, you've got to get the body to effectively denature itself proportionally and deliver raw organic materials to the areas where the new appendages are going to be. Both of these are going to cause issues in the long term because of putting a massive peak load on the digestion tract or the imprecision of said denaturing respectively. Of course, this doesn't cover off the other problem that you have, which is the need to support the new appendages with circulation, musculature, and skeletal changes. Wings are particularly problematic. If you're talking wings like the typical portrail of angels, then your wings need a massive musculature support through your back that those images traditionally gloss over. In birds, that musculature is the same as our pectoral muscles (hence why breast meat is so lean and large in poultry) because the wings are really evolved arms. Put the wings on the back however, and you've not only got to find a place for massive muscles back there, but the wings need to be very well affixed to the skeletal frame to support the weight of your changeling in flight, otherwise the wings will just snap off. This may sound all easy in theory, but that kind of extra muscle support means you need much more blood, a bigger heart to pump it, a higher metabolism and the digestive system to support it, probably a unique channeling system that guarantees blood flow to our very expensive (energy wise) brains even when engaged in the massively costly exercise of flight, etc. In short, you can't just add or remove appendages to increase the versatility of your changeling, you almost need to redesign the layout and capabilities of your internal organs from the ground up each time. That's time consuming and dangerous given the fact that these organs need to remain active during the transition. This is a little like trying to perform maintenance on the engine of a Boeing 747 at 2000m. At least 9 out of 10 aircraft engineers will tell you to land the plane first. So too is it with shapeshifting. It's not the new appendages that will cause the problem, it's changing all the support infrastructure (internal organs, muscles, bones etc.) that are already in use to support the old body so that they can change the new. [Answer] Multiple problems for any shape shifter: Mass; Where is the additional mass coming from? It wouldn't be instant; they would have to eat and digest a whole lot as they grow whatever extra limbs. Even if they are physically capable of rearranging their physiology, any additional growths would take time, it would be awkward and inconvenient. Look at how inconvenient and time consuming pregnancies are. It would probably be painful to walk around with a half-grown limb too. Weight; If the shapeshifter tries to make themselves bigger, they'll rapidly hit the cube square law. Bones will be strained, joints will wear. Even real life tall people can easily have bone problems. The shapeshifter will have to take steps to repair any strained musculoskeletal aspects. Mobility; Even if you can grow an extra arm, that doesn't mean you can control it. Motor control comes from the brain, and the nerves. You can't just copy and paste - you'd have to edit your own brain patterns to make use of it. And anything editing brains is risky business. Complexity; Which might be the biggest problem - this shapeshifter (presumably) isn't omniscient concerning biology. In order to redesign his own body, it has to understand how it's body works. You'd need a medical degree just to get started. Even the best doctor in the world wouldn't be able to rebuild a complex organ piecemeal, cell by cell. Risk; Biology is delicate. Changing it is dangerous What happens if the shapeshifter makes a mistake? There's a reason most engineers try to deactivate a machine before modifying it, but the shapeshifter can't do that. He's running live, constantly; he has to make changes as he lives. What if he accidentally changes his chemistry too much or removes a vital bit of nerves as he shifts, and ends up catatonic or dead? He's got no safety or reassurance; his entire existence is in his own hands. So overall, even if the shapeshifters could change their own biology to an unlimited degree, I don't think they'd be eager to try. A shapeshifter would maybe have one or two established and well-tested forms that they vary between as required - but trying to shapeshift freestyle would just be too difficult and risky. Maybe a community of shapeshifters would get together and try to figure out the best shape. Still, i reckon these shapeshifters would have more medical issues than any other race combined; they are effectively amateurs that have been given admin access to a complex machine. There is no end of ways that they could mess things up while fiddling around. All things considered, it might be easier for a shapeshifter to just... not use their powers. Live as a regular human, it's not so bad. Realistically, what are these shapeshifters going to use their powers for? Humans are already pretty well designed for all activities humans do. Growing an extra limb or wings seems like a lot of trouble for not much gain, really. Unless they have a very specific application in mind, it'd be easiet just to stick as a human. The most useful part of shapeshifting would be to strengthen and reinforce, rather than change. They'd be biologically immortal, if they could constantly update their cells to avoid aging. [Answer] Rearranging all the atoms in a body to form a new body is probably way too complex and precise to be plausible. Even a Super Computer wouldn't be able to compute these changes, so this is probably the harder way of going about explaining shapeshifters. An alternative might be to have the shapeshifted creature be in its complete form but hidden underneath a human form. For example a werewolf is desiccated/shrunken and hidden behind a human skin/façade/outerlayer. When the shapeshifted creature wants to turn back into its original form, it just pops out by rehydrating or something, shredding its costume. In this scenario the shapeshifted creature is not human, it just appears human sometimes. As for why shapeshifters have a human form, maybe they are good costume makers, or maybe they can grow human skin and features when they choose too over several days. Either way we are only dealing with the outerlayer of being a human so it requires a lot less explaining to make work. Explaining why a creature has a thin outer membrane that resembles a human is a lot easier to explain than a complete anatomy change. However I understand that this breaks your idea of having shape changers die from expending too much energy, and doesn't make for any attractive hero shapeshifter characters. [Answer] It might be interesting to include shapeshifters whose abilities degrade with age or strain. Considering how complex the changes they undergo are, it is not infeasible that as they age, their shapeshifting ability gets less and less refined. It would be similar to human theories about aging, that accumulated damages/alterations to DNA over years of time causes old age. It could be that shapeshifters as they age are more likely to accumulate failed shifts, things like horns they can never quite get rid of or skin that is never exactly the right color. Or it could be that the more they use their abilities the more they risk accumulating damage, like straining a muscle and creating scar tissue. They might end up stuck with certain traits because of the strain and their shifts become less realistic and more horrifying. [Answer] If a shapeshifter is not just changing shape but also copying the internal workings then, and this process is causing pain. I think there would be the possibility for the shapeshifter to create larger than normal copies of the glades in the body that produce the chemicals that block pain or cause pleasure. Some of these chemicals could even be addictive or have other side effects. ]
[Question] [ The devil is alive, and he walks among you. Eons ago, there was a battle between a powerful deity and a devil from the nine realms of hell. The losing devil, to avoid being killed, broke himself apart into many small pieces. These would be absorbed by children in utero, where the deity could hide and avoid being detected. These children would become the first immortals, where the spirit would manifest when they were killed. Various other immortals would be born throughout the millenias, until all of the devil's remains would be amongst humanity. Whenever immortals meet, they would be compelled to fight each other 1-on-1 in IMMORTAL KONFLICT! They are transported to a mirror universe that is a reflection of the mortal world. There, they fight to the death to rock music playing in the background with swords, which are an extension of their inner soul and can be summoned or hidden at will by the user. The only way to kill an immortal is to perform a fatality by cutting off their head. Afterwhich, their bodies would remain behind in the mirror world and their soul would be absorbed by their killer. The winning immortal would gain their memories and strengths to make them more formidable in battle against future opponents. After thousands of years, an event will take place in NYC known as the gathering. The few remaining immortals are compelled to come here and fight the last battles between each other. The last immortal would have absorbed all of the deity's pieces, and become the host vessel for the re-formed devil through which he will reincarnate himself. Back in the day, it was easy to have battles between immortals and keep it our of the limelight. With the 20th century, however, the world has changed. Advancements in technology, such as satalities, cell phones, GPS, cameras, etc, have made being undetected more difficult. why would this mirror world not worm and fail to keep it a secret? Because in the end.... There Can be Only One. [Answer] > > They are transported to a mirror universe that is a reflection of the mortal world. There, they fight to the death [...] Afterwhich, their bodies would remain behind in the mirror world and their soul would be absorbed by their killer. > > > As Battle pointed out in his comment, there is no way any mortal could find out about these fights. They take place in a parallel universe, and the loser's body is left there. The only thing people might notice would be that two people enter a location and only one of them leaves, so that's what we need to prevent. First off, you'll need a secluded area with no people or security cameras, where the immortals can warp into and out of the mirror 'verse without being seen. You'll need multiple points of entry, to reduce the chances of any one person noticing that the loser entered the place but never left it. And since we're talking about a secret death tournament for the right to resurrect the devil, you'll want a backdrop a bit more interesting than some run-down warehouse in the Bronx. So how about this? [![enter image description here](https://i.stack.imgur.com/E7GrI.png)](https://i.stack.imgur.com/E7GrI.png) Looks nice and secluded, doesn't it? It's the North Woods area of Central Park: [![enter image description here](https://i.stack.imgur.com/nrCLJ.png)](https://i.stack.imgur.com/nrCLJ.png) There are over a dozen roads or paths leading to Central Park, so your immortals can take different routes in and out. They can go at night to reduce the risk of running into anyone else in the North Woods; obviously people will see them in the rest of the park, but they'll just assume the immortals are tourists or something. And you can't get much more "New York City" than Central Park. [Answer] They now fight hidden in plain sight, on the planes of the virtual within any number of console, PC and online games. [Answer] To the best of my imagination, it might depend on the personalities of the immortals in play. A more cautious and paranoid immortal have spent the last two-hundred years in the equivalent of a bunker, upgrading and relocating as time advances. He or she intentionally avoid attention of both other immortals and all authorities. Honestly, most immortals would try to keep something of a low profile in order to hide from their rivals. You could also have immortals working for powerful organizations in secret, such as governments or hidden cabals. These organization might have a vested interest in keeping the supernatural qualities of their best agents a secret, and support the war between immortals as it makes their agents more powerful. Lastly, it seems like the only oddity that needs to be hidden is the immortality, as the mirror realm hides the fight and the resulting corpses from prying eyes. As long as the immortals don't paint giant targets on themselves by revealing themselves to either the public or the authorities, they should be fine. [Answer] Include some Immortals in government(provided they are living so long so must have gained good amount of money). Government then can make these wars private or can have a pretext of doing something else fooling normal people. [Answer] If someone is immortal, they have the ability to becomes immensely wealthy and powerful thus would have control of governments giving them the ability to cover up virtually everything. As long as the battles didn't involve massive explosions and didn't take place in main street or involve civilians, nobody would ever know. Any dead bodies can be chalked up to drug gang violence. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. If I was affixed to the surface of some solid spherical body in space (so as to ignore effects like me floating away), would it be possible for me to throw a tennis ball so that it went into orbit around the body? I imagine the average density would be an important variable since I can only throw a tennis ball so hard. I think, if the density was right, there would be some radius R of this spherical body such that I could throw a tennis ball and it would go into orbit around this sphere. For the average peson, what would the density and radius be of a sphere such that you could toss a tennis ball and it would go into orbit around this sphere? [Answer] When the hardest part to give my petty answer is finding out how fast an average person can throw a tennis ball, people serve them mostly. If you throw it is probably somewhere in 80-120 km/h range. Fastballs of pro's in baseball are 150-170 km/h, serves in tennis are close to the same number only in miles per hour. There is an infinite number of orbits = orbit velocities your tennis ball can go at, from circle to elliptical ones, till you hit escape velocity and then you have a chance at murdering some innocent alien few million years in the future. * Circular orbit velocity: [![V(orbit)=SQRT(GM/R)](https://i.stack.imgur.com/IJifk.gif)](https://i.stack.imgur.com/IJifk.gif); [![enter image description here](https://i.stack.imgur.com/v7XDZ.gif)](https://i.stack.imgur.com/v7XDZ.gif); Escape velocity: [![enter image description here](https://i.stack.imgur.com/Or8p7.gif)](https://i.stack.imgur.com/Or8p7.gif) or [![enter image description here](https://i.stack.imgur.com/uo75L.gif)](https://i.stack.imgur.com/uo75L.gif); G - gravitational constant [![enter image description here](https://i.stack.imgur.com/YoK2v.gif)](https://i.stack.imgur.com/YoK2v.gif); M - mass of both objects or mass of the planet in our case; R - distance between centers of gravity; g - gravitational acceleration aka. surface gravity. *Table with some fast calculations* [![enter image description here](https://i.stack.imgur.com/Blu60.jpg)](https://i.stack.imgur.com/Blu60.jpg) So 30-50 km radius for my speeds of 80-120 km per hour. Density used is what you would expect of a nonmetallic asteroid, but a rocky one at least. Of course, you could make a tennis ball orbit any asteroid with smaller values, just don't throw it too fast or it will escape. You can even let the tennis ball orbit you if you are okay to wait for something around the magnitude of 1-3 months for a revolution or way more if the radius is bigger. You can increase it by using a hollowed/altered asteroid, you can play with new mass and radius. How big you could build it before it collapses? That is a big question of itself. Just find what asteroid fulfills requirements of your story and then tweak it for this stunt. ]
[Question] [ In a dystopian future, genetic editing, stem cell research and cloning have become commonplace. Humans in embryo can be genetically modified and designed to a immense variation; some people can give themselves scorpion tails, for example, while others make their brains twice the size. Professional swimmers have fins and webbed digits, professional bodybuilders have inhuman muscle mass etc... Human anatomy can be redesigned to whatever shape a scientist can imagine. Due to cultural collapse, there are no legal or moral restrictions on the extent of genetic editing. A mega corporation wants to exploit this. This corporation presently hires millions of office workers, fulfilling a multitude of admin and secretarial duties. They consider regular humans to be inefficient and cost ineffective. The corporation wants to lay off all their current admin workers, and replace them with an army of cloned super secretaries. So, what modifications should be made to the typical human design in order to make these office workers more efficient? Answers might include additional arms to help them type faster, or modified brains so that they will not be distracted by any social activities, or even crippled legs so they can never leave their desks. The admin jobs in question are all low paying, require limited creativity, and are based solely around using computers. For legal reasons, these factory farmed workers are not 'human', and no human rights apply. The corporation cares solely about reducing cost and streamlining efficiency. They want to design a template for the ultimate office drone, to be reused across their business. Anything biologically feasible is possible, with some flexibility considering they're using future tech. [Answer] For a more dystopian setting: Improve eyesight to reduce electricity costs and reduce industrial espionage. Additionally, reduce the size of text on monitors to the minimal resolution to have more information displayed at one time. Reinforce the spine and other musculoskeletal structures to reduce ergonomical injuries such as back pains or [repetitive strain injury](https://en.m.wikipedia.org/wiki/Repetitive_strain_injury) when saving on office furniture and peripherals. Supply large fat reserves and the means of utilising them without feeling hunger or thirst to reduce the time spent feeding. Reduce temperature sensitivity to reduce the cost of maintaining HVAC systems. Increase the amount of hands, arms and digits to allow for maximum desk coverage. A digit for each key on the desk would be ideal, with more keys meaning less typing through the use of [stenotype machines](https://en.wikipedia.org/wiki/Stenotype). Reduce the size of or entirely remove the [prefrontal cortex](https://en.wikipedia.org/wiki/Prefrontal_cortex) and other non-essential parts of the brain to reduce energy consumption and unnecessary brain activity. Adjust the metabolism and brain to imitate that of giraffes to reduce sleep to up to 3 five-minute sessions per day. Modify the workforce's appearance to be as grotesque and inhumane as possible to reduce the uprising of human and animal rights organisations. Boost the immune system to reduce the risk of infection in your cramped, dark, humid and dirty workhouses. [Answer] I think the most important trait of an office drone would be agreeableness - the ability to stay positive, happy and kind even in adverse circumstances. Agreeableness is about as heritable as is height, so you could definitely engineer more of it into people. Of course, a really high intelligence would be help at the office, as would an eagerness to please and an urge to seek validation in the approval of peers and bosses. I'm sure that an aversion to conflict also has a strong genetic component, and it would be valuable in an office drone. He or she should also be a very consciencious but minimally neutrotic person, someone who brings joy to others every working day. Basically, you would want to engineer a Smithers from The Simpsons, but even smarter, more cheerful and more capable. ]
[Question] [ Demons are incorporate, malicious spirits from the depths of hell. They require a human form in order to pass into the mortal realm. A dark sorcerer can sacrifice an individual in order to trap a demon in the victims body, enslaving the spirit to their will. This is a risky process that can come back to harm the user if the demon isn't bound correctly. Ancient runes and sigils must be carved into a living victim's skin. This will bind the demon to the body, trapping it and subjecting it to the sorcerer's will. Then the victim is killed through a dark ritual. The organs are removed from the body, as well as the bones, cartilage, etc, until only the skin is left. It is then placed over a ritual circle, while the sorcerer chants an ancient incantation that opens the gates to the netherworld. The circle provides the passageway, splitting the ground and allowing the demon to inhabit the skin of the victim. The runes keep the demon in the skin of the victim, trapping it similar to a prison. Since demons are just bodiless spirits, why would a victim's insides have to be removed in order for the demon to possess them? [Answer] Because they have to be removed. This is a magic system that you're creating. By definition, the rules are also yours to define. Why do you need a ritual circle? Because demons only arrive via ritual circle. Why do victims have to be hollowed out like a pumpkin? Because when they tried it on someone who still had their insides, their spleen exploded, killing the victim and three practitioners. Why can't we at least keep their skin on? Flaying someone is messy work. Because when a victim had their skin on, the demon couldn't secure a foothold inside them and was dragged back to the nether regions, and a bunch of expensive reagents were wasted. [Answer] > > Since demons are just bodiless spirits, why would a victim's insides have to be removed in order for the demon to possess them? > > > I don't know mate, that's non traditional lore and totally on you. Which sort of makes this question "opinion based" and closeable. But if you are asking for a mythologically justifiable reason that could be tied to this then perhaps: 1) (logically) preservation- skin aka leather lasts a whole lot longer if removed from more decomposable flesh. Afterall you want your demon slave sticking around for a good long time. 2) The Egyptians believed the heart was the seat of the soul, since the soul prevents possession then removing the heart is critical. 3) Temptation - Physical appearance leads to raw impure carnal sexual attraction which leads to sin. By this logic the skin could be the only organ inherently unholy enough to support the demon. It also justifies self flagellation as a means of penance. [Answer] Basic hygiene Have you any idea what happens to a dead body if you just leave it lying around. It will stink, get infested with maggots, the internal organs may explode, excrement will be expelled, etc. Obviously just using the skin (and preferably using some form of preservative) will avoid all this disgusting mess. Sure demons are horrible and scary but they are not zombies. [Answer] While demons ligation to the physical plane is much more tenuous than our own they are still corporeal beings. They can move through air and earth alike but density obscures their conveyance. To realize greater advantage a demon must exist in the void of a vessel; unhindered by blood and bone. For it is the boundaries between thick and thin that allows demons to gain the most purchase on the physical realm. The older the boundary the stronger the interaction. This is why a demon can only escape through freshly broken earth or an adult is a better surrogate than a child. [Answer] Have you ever looked at a property online but the windows are boarded up and there’s no natural light? Or gone to view a new flat only to find it’s full of a lifetime’s-worth of clutter and cardboard boxes? It’s the supernatural equivalent of that. Demons simply won’t want to inhabit a body if it’s cluttered up with icky internal organs and hasn’t got a nice view to the outside world. Etching the runes is an occult ‘property for rent’ sign (and a cosy corporeal body is waaay better than your typical infernal bedsit), but before any tenant will move in and start working for the roof over their head (so to speak), they want to know that the place will be properly cleaned out and opened up or they simply won’t sign the lease. Basically your average dark sorcerer needs to be a reasonable landlord or not even the prospect of a physical bachelor pad will draw in the demons. [Answer] ### Demons are corporeal on Earth Demons may be incorporate in the netherworld, but on Earth they must be corporeal. After all, every creature with a will on the Earth is corporeal. Ghosts? Those are just stories. If a demon comes through the portal from the netherworld, then its essence takes a corporeal form on this side of the portal, just as if a wizard wishes to go into the netherworld, his corporeal body cannot enter and only his astral projection will pass through. ### Demon's corporeal forms on Earth is ... messy While you and I and horses and trees are made of the normal stuff of Earth, (Fire, Earth, Air and Water) demons are ... not. Their corporeal forms are made of all sorts of impossible magical elements. Not only would they drive humans to gibbering insanity by just looking at them, but their unstable bodies interact in strange ways with the environment. Just try touching them with iron, for example, and see what happens. In order to contain a demon's form on Earth, it must be covered with something, and something that was once alive, at that. The skin of a creature, imbued with the proper magical rituals, can both allow a demon to take a set form on Earth, and contain their magical power to prevent unfortunate reactions. ### To do useful work on Earth, Demons needs a 'covering' to put over their forms What better way than human skin? This gives several advantages, not least that the demon is molded into a human form and can do human work and interact with humans. After all, succubi would be very inefficient if they were trapped in the skin of a cow. Plus, one advantage of a skin suit is that a perfectly normal looking human can suddenly pull back his face, revealing his true form, and rendering anyone who sees him mad. Demons don't have to be trapped in a human form, of course, you can make some sort of vessel for the demon, known as a familiar. But, generally, humans and small animals are the only demon-summoning recipes you will find in musty old tomes, which explains why you don't see many demon rhinos. [Answer] # Evolved Protection Since demons are real it can be assume that they existed throughout our evolution. It could be that back in time (a little after primordial soup, when skin evolved) that demons could at will take over any organic being. They did this because while they were in control they would feast on the victims organs (if not feast then they would get some other benefit derived from organs). Skin was an evolutionary defensive response against this (Those that could not get possessed had a better chance of surviving). Now since skin is our shield against demons, it could also be used to trap them. The reason why everything else is removed is simply so that the demon has nothing to feast on and get stronger (could get strong enough to break the sigils). ]
[Question] [ I'm the city designer for a new city we're calling Morrowville. Having some of the worlds top minds, flying cars have been invented, but can only fly a few feet (2-4) from the ground and not everyone has made the switch, so roadways are still required. I've proposed a number of traditional roadways to the city and tried to reduce traffic where possible, but was told the designs weren't "innovative enough". I've been tasked with making all roadways (streets AND highways), with 3 levels, to give the city a futuristic feel, and to provide the city with extra zoning space for businesses and houses. I have had no problems with the base design yet, but I'm having a significant amount of trouble when it comes to intersections and layer traversal. The levels need to be able to merge vertically and horizontally at designed intersections, similar to freeway heights. For instance, on a normal road, one might need to turn right off the freeway, and would simply get in the correct lane and turn right. On this new design, I could have a possibility of needing to turn right onto the upper road from the middle or bottom road perpendicularly. I also need to be able to get from the bottom road to the top road in the same fashion, and there are only three requirements for the road. 1. It must be 3 levels, all traversable from any roadway. 2. It must not slow down traffic unreasonably (No stopping for some high speed elevator). 3. It must be compact, the normal cloverleaf intersections for 2 directional roads apparently "just doesn't work" for them. 4. No budget, this city is the future! Material requirements are met, and businesses/houses need to be able to be placed along this, although for highways and freeways the railings will prevent that except for at designated toll booths. We're just waiting on the design, so please help me keep my job! How can I make a 3 level roadway that has easily traversable intersections and traffic alleviating properties? Note: * Time period is 59 years from now. * Technical requirements can be stretched, but I'd like to keep it relatively plausible. No blatant hand waving like portals. * There's no magic in this world. * The businesses on each level are class based. Middle class in the middle, you get the picture. Edit: Please excuse my atrocious artistic abilities. [![Every single area needs to connect.](https://i.stack.imgur.com/BdVX6.png)](https://i.stack.imgur.com/BdVX6.png) I need every single area to connect, and find that the roads will cross no matter what traditional pattern I use. [Answer] I'd propose standard intersections for all horizontal crossings (minimal traffic disruption with efficient AI controlled signalling). All vertical crossings are handled with spiral distributors. [![enter image description here](https://i.stack.imgur.com/NG8CF.jpg)](https://i.stack.imgur.com/NG8CF.jpg) White lines indicate medians. Horizontal Junctions. Traffic following any of the blue paths (left turns) will be guided by yield / caution signals. Traffic following red paths (right turns) and all through traffic will be guided by stop / caution signals that are integrated with traffic flow monitoring systems. Vertical Junctions. Traffic flowing from level to level (spiral turns) will be guided by yield / caution signals. While a "level 1 to level 3" spiral could of course be built, its practicality is of dubious nature. Dividing the bi-level spiral into two single-level spirals saves costs and maximises utility. NB: in the picture, only the left-moving "down-spirals" are shown. I.e., those spirals bringing left-moving traffic from level 3 to level 2 & from level 2 to level 1. The "up-spirals" for left-moving traffic would be off to the right of intersection. Likewise, only the right-moving "up-spirals" are shown. Right-moving "down-spirals" would similarly be off to the right of the intersection. Similar "spiral towers" would also be constructed for the orange / green / yellow roads. An actual traffic spiral, as used in a car park: [![enter image description here](https://i.stack.imgur.com/ovmHX.jpg)](https://i.stack.imgur.com/ovmHX.jpg) [Answer] Each stack of roads is one-way. Neighborhoods feed to/from the correct road directions of their block and level via quarter-loop side-streets. Unfortunately, this means that half of the blocks need to be served to/from fast lanes of their adjacent roads. On some blocks, there are a pair of stacked ramps adjacent to the slow lane. On some blocks, the pair of ramps goes up to the next level; on other blocks, the pair of ramps goes down. On each level, there is a speed-up/slow-down lane that continues from one ramp either to the next ramp, or to the next turn. Turns occur at the crossings of roads on the same level. Turns connect a speed-up/slow-down lane to another speed-up/slow-down lane. If the fast lane is on the left, all of the turns are right-turns. There are no clover-leafs. To make a U-turn, you go half-way around a block. To make a left-turn, you go three-quarters of the way around a block. You can have different speeds on different levels. You might have one level buried, one level at the surface, and one level elevated. ]
[Question] [ Like the title, my world has drastic tides that complete a cycle in roughly 25 days. is this possible? My limited knowledge of astronomy leaves me pretty limited. I understand that there would have to be a fairly large cosmic body acting on my planet to cause such drastic tides, but that the body would have to have an irregular orbit (if even possible) to extend the cycle to 25 days. anything would be appreciated. [Answer] Yes it is possible. Take Mercury, for example. 'It takes Mercury about 59 Earth days to spin once on its axis (the rotation period), and about 88 Earth days to complete one orbit about the Sun. However, the length of the day on Mercury (sunrise to sunrise) is 176 Earth days.' from <https://www.windows2universe.org/mercury/News_and_Discovery/Merc_orbit_reson.html> Tides are not just created by moons, but by the sun. The closer to the sun, the stronger the tidal effects. The shallower the water, the greater the tidal effects. The slower the planet spins, the longer the 'day' and the solar tide. The lower the gravity of the planet, the greater the gravitational effect of the sun on the water. The length of the solar day determines the length of a solar tidal cycle. However, it depends on what you mean by a 'day'. A solar day and a solar tide would have to coincide. Or your world could be a moon around a massive planet, which creates a 'moon tide' on the moon itself. Thus, the moon tide and the solar day do not have to coincide. The further away the moon is from the planet, the longer it takes to make one revolution. The length of the moon tidal period would be a combination of the rotation of the moon around itself, and the rotation of the moon around the planet. The length of a solar day on the moon would be determined by the rotation of the moon around its axis, and the rotation of the moon-planet combination around the sun. Eclipses would be a factor. On Earth, the time of a moon tide and its strength is determined by the Earth's rotation around its own axis, and the period of the rotation of the Moon around the Earth. See the referenced article for an example of how this can be calculated for the Sun-Mercury combination. You can do all of the calculations if your readership is absolutely demanding, or you can just assume the parameters are correct on your world for a non-discriminating readership. For a short story, assume. For a space opera, calculating it is perhaps the preferred method. However to be science-based, your calculations would have to include an analysis of the tendency of the moon-planet combination to be tidally locked. [Answer] Have a moon in an eccentric orbit. Generally it will be not much closer than our Moon is, but on one day of the 25, it will be very close. If it is a tenth the distance of our Moon, tides on that day will stretch hundreds of miles inland and recede similarly far. To be less extreme, just change the distance (it varies as 1/distance cubed) so having it be 1/2 or 1/3 the distance of our Moon would probably do the trick. Of course, this might not exactly be what you are asking for. If you truly want a 25-day cycle (i.e. one high tide and one low tide every 25 days), then have the moon in an orbit of 1.02 days; however, if it were the size of our Moon, then the tides would be about 800x the size of Earth's. This should be made less extreme by making the moon 100x smaller than Earth's (it would also be at about 43000~44000 km semimajor axis; if it is similar density to our Moon, the apparent size would be roughly the same). As an aside, radius of the planet increases tidal force proportional to it, but I am not sure whether that would increase the range as well. [Answer] Tidal effects have a synchronizing effect on the planet and its moon. Given enough time, the moon's orbit and your daily rotation can get arbitrarily close. As for the strength of the effect, the easiest way to do this is to simply have a very flat tidal basin. If the land is very flat, your tides can move as far inland as you please. Indeed, this is made even easier by your long tidal cycle, giving the water all the time it needs to move into place. ]
[Question] [ Let me pose this question as a hypothetical. Your ship warps/jumps to a planet 50 light years away. You set up a radio signal receiver. Theoretically, the radio is going to receive radio-waves from Earth from 50 years ago. My question is even with a powerful receiver, would the signal be clear enough that I could listen to 1968 radio stations without problems or would the signal have degraded to an almost undecipherable static? if so, what factors would be the cause of the degradation? Can gravitational or other interstellar phenomena (radiation?) degrade a radio signal? [Answer] No, you can’t pick up radio broadcasts from fifty light years away without a receiver that’s more powerful than anything we currently know how to build. The degradation is caused by the inverse square law — a broadcast that’s designed to be picked up 1,000 miles away will be about 22 orders of magnitude weaker at a distance of fifty light years. See [this Physics Stackexchange question](https://physics.stackexchange.com/questions/245505/from-how-far-away-could-earths-telescopes-detect-earth-like-radio-signals). ]
[Question] [ Background 100 years in the future, Mars has been colonised. New settlers and resources arrive from Earth every 26 months (when the planetary orbit lines up best) by first taking the space elevator to Earth orbit and then using a large one-way ship to get to Mars. The ship is designed to be one-way, landing on Mars and then stripped to be reused around the Martian colonies, a Mars space elevator is in the works, which, once completed, would allow true two-way travel between the Earth and Mars or at least that was the plan before the blackout happened. One day all communication with anything outside Mars stopped (Earth, the next colony ship that was in route to Mars & even the crew working on the Mars space elevator in Mars orbit), an event that among the Martian settlers came to be known as the blackout, no one knows what happened, but for the purpose of this question, it's safe to assume that every human being outside Mars is dead and every man-made machine outside Mars stopped working. Tech level The technology of the Mars colonies is near future (100 years) earth level. Things such as food, water and air have been fully self-sufficient even before the blackout with Mars-based greeneries, fish farms, algae farms, and vat-grown farms providing food, fuel (biofuel), bioplastics & a certain level of medicine (basically any form of medicine that can be grown), it also provides some building materials (wood & bamboo) while some other resources (stone, sand (for making glass) metal, water, earth elements) are mined on Mars, the only things that were dependent on supply from Earth were things that are so advanced that they couldn't yet be produced on Mars, like the more advanced parts of computers & cellphones, advanced medicines, advanced robotics, etc. The colonies' electricity comes from multiple sources, solar panels (imported from Earth) provide some power, but mostly it is either nuclear power or from burning local biofuel. Mars is not terraformed, and the colonists live in a mixture of domed cities, caves, underground areas & above-ground buildings made from local stone & metal. Travel between areas of the same colonies never requires stepping outside an unpressurised area (underground subways being the most common form of transport in larger colonies and walking in tunnels in the smaller ones), travel between colonies is usually done with pressurised above-ground vehicles and trains but some colonies which are close enough to each other also have underground transport from one another. Mars society While most Martian colonists are Earth-born, there is a small (but growing) number who are Martian born. Giving birth on Mars has proven possible with about the same level of difficulty it is on Earth; it's entirely possible to give birth on Mars without any medical assistance, but most still prefer to see a doctor (much the same as on Earth). Mars is, in fact, an array of colonies connected to each other, each providing some resources to other colonies, but no single colony is the sole provider of any resource. There is some friendly competition among the different colonies in much the same way that some city residents in the same country like to talk about other cities. Still, when the blackout strikes, they pull together to survive. Martian colonists put a lot of emphasis on being as self-reliant as possible, even before the blackout. 3d printing and machine shops are common occupation on Mars as well as other productive professions (there aren't a lot of advertisers on Mars, assume all colonist has useful skills or are young and still in school). Assume the colonies are of the minimal size needed to survive long term; if your answer requires a minimum of 10,000 people to survive, then that's the colony's size; if it's a million, then a million it is. The question Can the colony, as described above, survive long-term? For this question surviving means the most basic of needs being met, if they have water, air, food, a place to put their head for the night & the ability to give offspring who will get the same, that's enough, even if any sort of luxury they used to have is gone in the process. As time passes, what resources they had from Earth will break down, and if they are required for survival, they will need to be replaced with a locally made substitute. Is there any piece of equipment or resource that couldn't possibly be made by the colonists that is required for survival on Mars? If the answer is no, please provide the exact reason why the colony can't survive, don't just say, "They couldn't possibly reproduce anything needed without Earth's help", but rather say something like "X requires the element Y which doesn't exist on Mars and can't be synthetically manufactured dooming everyone". [Answer] Medicine You mentioned that martians don't have access to or the ability to create the advanced medicines they used to have sent in from earth? A very real reason the colony could fail could be plague. You have a ton of people with heightened radiation exposure living in dense proximity with possibly simpler and poorer diets. In addition they have lived in a sterile environment, and just like anything in our bodies if you don't use it you lose it, so their immune systems would already be struggling in addition to the extra radiation and potentially less varied diet. A plague could kill off enough of the valuable labor force that they can no longer support the industries critical to survival. Producing things like vaccines is a very major hurdle they would have to face, since doing so is already incredibly difficult here on earth. Additionally the fact that the simple antibiotics they can develop could be ineffective against resistant strains. One person living in close proximity with many others developing an antibiotic resistant strain of staph or something could rapidly infect others. Note: Its not impossible to overcome, its just a real threat to the success of the colony that I think a lot of people tend to overlook in space colonization. [Answer] > > the only things that where depended on supply from earth was things that are so advanced that they couldn't yet be produced on mars like the more advanced parts of computers & cellphones, advanced medicines, advanced robotics, etc. > > > That's the rub. Today's technology relies on computer chips to control just about everything. You've got a 3D printer? Well, you need a controller. You've got a vehicle? Well, try getting it to move without the chips that control its motors. I'd wager that you wouldn't be able to open a single door, run a single air conditioner, convert power from the solar arrays to usable voltages, run mining machines, run nuclear power plants, or use about any other kind of machine that your mars population relies on, without some chips that are contained within that same machine. Chips are literally everywhere in modern life, and will be even much more so in your colonies. In addition to being everywhere in modern life, chips are by far the most difficult things to create. Chips seem cheap to us, because they are created in large series once the process has been fully set up. But setting up the process is insanely costly. So, your Martians will be very hard put to create their own microchip fabs as quickly as they need. Because, and that is the final nail in the coffin, chips are irreparable once they are broken. For the first years, everything will continue working inside the colonies, but anytime a chip fails, it's gone for good, and there is no way of replacing it. --- After about five years, people would start feeling the pains of the resulting decline in working machines. After about ten years, some areas may get into serious supply problems, because the amount of machines that are still working is just too small. I think, your colonist won't be able to go more than twenty years without people dying from the consequences, and violent fighting for the remaining working machines. After about fifty years, Mars should be as dead again as it is today. --- The only way around this fate seems to be, to have the Martian colonies be so large, and so focused on providing for themselves, that they are already on the verge of building their first own chip fab when the blackout strikes. The further this fab is from outputting its first chip at the time of the blackout, the more dire the consequences will be for the Martians. [Answer] My first comment was made moot by the edit restriction to 100 years, so I give you a second answer. One restriction that will almost be certain is in the area of advanced research, especially physics. There is an antecedent on earth, to a limited extent. I sincerely doubt that anyone would have built an equivalent to Cern on Mars within 100 years. This particle accelerator is fundamental to any further exploration into particle physics. I suspect that we will still be exploring the nature of quantum physics, and there will still be particles that we know about in theory only. The antecedent today is America. A few decades ago, the American scientific community made the deliberate decision to stay out of particle physics exploration, putting their money elsewhere. Cern was built in Europe, and this meant America was out of the Nobel Prize in Physics for over a decade. America stagnated, frankly, and has missed several decades in physics advancement. It is still stuck in the 'Einstein period' - cosmological physics instead of particle physics. So your Martian intellectual community will go through a very long drought in advanced physics discovery. I suspect that things like advanced spaceship drive technology and quantum mechanics applications will be put on ice for a very long time. Any scientific advancement will be limited to explorations that can be done in a standard general-purpose University-type lab setting. It will not necessarily be any missing 'material' stuff that impedes survival, but it will be the missing research mega-infrastructure that limits advancement. The physics textbook will not get much thicker for a very long time. EDIT TL:DR Without a Blackout, 200 years from now Mars will be much like my first answer. With a Blackout, Mars in 200 years will be very much like Mars is in 100 years from now. EDIT Each of these is a machine that produces the most modern chip. Easy to get one of these to Mars. [![Each of these is a machine tah produces a chip](https://i.stack.imgur.com/6ZCZz.jpg)](https://i.stack.imgur.com/6ZCZz.jpg) from <https://www.theregister.co.uk/2014/01/15/intel_fab_42_stays_shut/> [Answer] # I don't see any show stoppers. 100-200 years in the future, I will presume you have all the energy you need indefinitely, by solar or fusion. Although the sunlight is much reduced, all the materials you need to build solar panels are available; and the collection farms can be as vast as necessary (and there are no cloudy days!). They could be built, cleaned and maintained by non-intelligent robots; guided remotely by humans; energy farming could be one of the many jobs on Mars. Also, to defeat another suggested fault, the Mars Rover [has found nitrogen in the form of nitrates in the crust of Mars,](https://www.nasa.gov/content/goddard/mars-nitrogen) released simply by heating of the sample. So nitrogen can be mined by automated machines powered by those solar gathering stations. With sufficient energy and simple centrifugal mining, crust and rock could be crushed, heated to release gases (which we capture and separate), melted, spun at high G while cooling and separated into its constituent heavy parts; primarily silicon. Automated chemistry should be advanced enough by then (100-200 years from now) to let us produce all the compounds we need. They can produce their own computer chips and electronics; most of that is automated and computer work, which by Moore's Law will be awesomely fast by then. For that same reason, computational chemistry will be so advanced, we should be able to recombine those elements produced from processing the crust as needed to produce any compounds we need. One problem you might have is a limited genetic pool, you are creating a definite population bottleneck. The human race may have been through a period with less than 10,000 individuals; I don't know if you have even that many on Mars. However, you could immediately, with their tech, harvest and preserve the DNA of every one of them, collecting cheek-swab samples from all, and both sperm and egg from adults, to remain frozen (pretty easy on Mars), in order to preserve whatever biodiversity you already have. Biological tech should have advanced by this point to actually allow cloning, if necessary, and we are already having some success with CRISPR to replace individual genes with other genes, that tech should be very routine (and even old-fashioned) in coming centuries. [Answer] Your Uranium may run out. As far as I'm aware Uranium isn't available on mars, and being a major source of energy makes it important for your colonists. Luckily you can make do with extra solar panels until you can make biofuel production efficient enough to replace your nuclear plants. (Mars may have Uranium, its hard to tell from earth though.) [Answer] EDIT This answer has been made moot because of the change in the question to 100 years in the future, but the last part is still relevant. In 200 years, Mars will be completely self-sustaining. If the timeline for the development of North America is any indication, the population will certainly be pushing on one million. With that many inhabitants, there will be enough intelligence to solve pretty much any problem that comes along. It will all be just engineering. And in 200 years, the physics textbook will be at least 100 times thicker than it is now, and totally integrated with the biology textbook. Quantum effects and quantum mechanics will be routinely used. Quantum computing and quantum entanglement will be integrated into everything. Manufacturing will have progressed pretty close to that of Star Trek replicators. It will be 3D printing on steroids. Any material, including metals. Once printed, they will be molecularly fused together in post-processing. Enter the right file, and out pops anything you need. Instructions will be on the Internet (or whatever it becomes) for any chemical reaction or process. Drugs and medications will be produced biologically, using Crisper gene editing. We will have perfected DNA-style manufacturing, where the 'product' is coded in synthetic DNA and replicated pretty much like cells manufacture body parts today, except that the 'amino acids' and the 'proteins' will all be boutique designed, and they will be the building blocks of anything we want built. There will be no need for large scale mega machines. Thousands of small bots, instead. Each bot made in a synthetic custom-designed biological simulation cell. Electronics components are surprisingly easy to make. What limits their productivity on earth is not the ability to manufacture them, it is intellectual property rights. Patents. I have no doubt that your Mars survivors will not be hampered by any legal restrictions on patent infringement. [Answer] If this is set 100 years in the future it is far from clear whether your colony will have or need any humans at all. Can't AIs and robots do everything necessary, more safely, efficiently and cheaply than humans? (And it would certainly be smart enough to make anything needed locally) I suspect any humans would basically be like the idle aristocracy of the 18th century, pretty irrelevant to the operations of the Martian machinery. They might be completely plugged in to their version of the internet on a permanent basis, which might offer a much more rewarding life than anything Mars had to offer. Would they even notice Earth had gone? [Answer] Anything that demands genetic code, manufacturing, large/expensive/complicated items First, is such a colony credible? Well, Andrew Weir made a viable one-person Mars colony credible. [![enter image description here](https://i.stack.imgur.com/P8yoZ.jpg)](https://i.stack.imgur.com/P8yoZ.jpg) Image Credit: Netflix So add another 100 years and — yes — getting a colony started is very credible. Second, is it long-term sustainable? With Earth support, if it is startable, it is sustainable. There is nothing on Mars that risks running out that makes a colony be able to start and then suffer a shortage. Third, is it sustainable with no outside support? Here, I say you can use your author's prerogative and add suitable amounts of helps and hardships. With a time gap of 100 years, you can credibly add enough enablers to find that fine balance of both credible survivability and credible problems that makes for a good story. So, to answer your question: what would be credible issues when Earth support is cut off? * Anything that demands a complete genetic code to work, in other words plants, agriculture, bacterial cultures needed for medicine, water treatment, sour dough, beer, cheese, penicillin. * Rare Earth Materials, such as neodymium, indium and other such metals that we find in pretty much any modern tech, especially electronics. * Earth crated/served hardware, such as satellites. What if — for instance — the Martian GPS network and satellite communications was shipped from Earth. As the existing network degrades, or is maybe even shut off due to malicious interference from Earth, this will cause hardships. But also large machinery, such as dirt-movers, mine borers, extractors, manufacturing plants. You can select any number of things where the Martians discover "Oh, bother... we cannot make those here". The point is, you — as an author — can both credibly make such a base sustainable, and also credibly create hardships. And with a 100 year time span, you will have a big pallette of both enablers and hardships to choose from. ]
[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/123387/edit). Closed 5 years ago. [Improve this question](/posts/123387/edit) Okay trying to make this as narrow as possible. I hope. I have world where magic has returned in modern times. It came back in 2010 but the story takes place in 2018. In this word some people have been changed into non-human or part human beings. Centaurs, Naga, Mermaids etc. Most Centaurs are normal horse body with a human torso. They weigh as much as a horse. So I'm asking about the mechanics of transportation for a Centaur, the vehicles possible and how a Centaur would control a vehicle. They still use oil and gas for now. [Answer] Mustangs! No? Maybe pony cars? Get it, because...no? Oh alright fine. It seems like a broad question, but assuming you want something based on current, existing vehicles, your only real option is an up-fitted, high-roof commercial van. [![Ram ProMaster commercial van](https://c4d709dd302a2586107d-f8305d22c3db1fdd6f8607b49e47a10c.ssl.cf1.rackcdn.com/thumbnails/stock-images/5f918af6e02c0f8d1d03d703499cec05.png)](https://c4d709dd302a2586107d-f8305d22c3db1fdd6f8607b49e47a10c.ssl.cf1.rackcdn.com/thumbnails/stock-images/5f918af6e02c0f8d1d03d703499cec05.png) Why a commercial van? For a few main reasons. 1. High roof available to allow the centaur to enter from the back 2. Usually truck-chassis-based, to support the weight 3. Commonly up-fitted for a variety of duties Your centaur is, assuming normal human and horse sizes, probably 8-9 feet tall and weighs close to a ton. A normal car is not going to carry 2,000 pounds of driver that's still probably 5 feet tall when they are sitting. A truck-chassis work van could. The high roof is going to be necessary to allow your centaur to get anywhere close to the driver's position, otherwise you're going to need some sort of conveyor system to get them in place. With a high roof, they can enter through the "trunk" doors, walk up to the front, and then sit. In addition to the physical size requirements, these types of vans are very frequently outfitted with a variety of add-on equipment for a number of uses. That means third-party up-fitters are used to working with them, and should be able to easily adapt some equipment to meet your centaur's needs. Since your centaur is going to be "sitting", all-hand controls will be necessary, but that's not a problem. We currently have [vehicle hand controls](https://www.mobilityworks.com/hand-controls/) for people without use of their legs. ]
[Question] [ Obviously there would be a lot of small (not to mention a couple large) changes humans would need to get used to on a planet that rotates much faster than Earth. The biggest one I’m concerned about right now though is how they’d measure a day. Let’s say that, barring a few incidental adaptations or changes in sleep cycles, this planet’s inhabitants were humans as we know them. If a single 24-hour period on this planet sees three periods of “night” and three of “day”, then how might people start to think about and label this? Would they even attempt to frame it in terms of the 24-hour period Earth humans do, or would they simply accept the new day-night cycle and sleep multiple times in short bursts within 24-hour periods, coming to see a day not as a 24-hour period that’s split by multiple nights, but as a much shorter eight or six hour period of light followed by six to eight hours of darkness? How would they come to see their planet’s natural satellites, if it had any? To clarify, this is a fantasy world. The humans living in it are, with the usual handwaving and suspension of disbelief, the same as humans in the real world. They’ve lived on this planet all their lives and have no preconceived notions about how time is measured on Earth or any other worlds. [Answer] If the same sun rises and sets three times within 24 (Earth standard) hours, then one day is eight hours and not three sunrises per day. Nothing magical about those 86,400 seconds, except that homo sapiens comes from a world with this rotation period. # So you're asking, how would humans adapt to a shorter day? Usually that question comes in the context of a science fiction setting, where artificial light sources are a given, along with species developed on a different planet. In your fantasy world, the humans are presumably from that world. My guess: * People would still try to work during all the daylight periods. Artificial light sources are too expensive and also unsuitable for fine work. * Only one meal per day. * Logistics might make it difficult to return home from the fields every night, to there might be a temptation to alternate one 'siesta' period (short nap between work) and one 'true rest' period. During 'true rest' one turns in before nightfall and wakes after dawn, during 'siesta' one sleeps through the darkest hours of night. + Villages become smaller to keep them closer to their fields. On Earth, it was possible to have a field one hour or more from the village. * Different villages might not be able to agree which are nights are which. One might be able to switch at the expense of some jetlag. [Answer] They would definitely label each change between light and dark a "day". Like we label 7 days as a " week", they might find a similar label for a convenient number of days. Like a "month", that was originally one cycle through all moon phases, other celestial bodies visible to these people will likely influence how they structure their time. They will also feel sleepy during dusk and probably sleep several hours of each night. This is caused by our bodies producing the sleep hormone melatonin when the light intensity decreases and the color of ambient light turns to red in the evening. They would probanly eat only one meal per day, as this yields the best ratio between preparation time and calory intake. Work might be structured as 3 or 4 days of work, followed by 2 days of free time. Due to the short days, going to work for half a day and then going home for free time is not practicable. You loose too much valuable time on your way to and from work. It's also very probable that most people either never leave the place where they live or that they have some sort of mobile homes for the purpose of travel. These could also be used to stay at your work site at night to eliminate the need to walk home, loosing valuable time. ]
[Question] [ I've been working on the anatomy of my boron based life using alternative biochemistry. But I've recently came across a problem that I can't solve on my own. In oxygen breathing life on earth, the macromolecule known as hemoglobin located in the blood is what transports oxygen throughout the body. [![enter image description here](https://i.stack.imgur.com/veiRg.jpg)](https://i.stack.imgur.com/veiRg.jpg) However, my boron based life doesn't breathe oxygen, in fact oxygen is quite dangerous to my species. As it would form strong bonds with the boron which would kill off the life on my planet. Instead, my boron based life breathes methane which is then broken down in their body for the hydrogen. Due to this function in their body, what alternative macromolecule could I use in their blood to transport the hydrogen that doesn't also contain oxygen. I hope this question is clear enough to answer. If not, let me know in the comments. [Answer] Need something to carry hydrogens? Digging boron? How about boron hydrides: boranes. <https://en.wikipedia.org/wiki/Boranes> [![enter image description here](https://i.stack.imgur.com/r3BUp.jpg)](https://i.stack.imgur.com/r3BUp.jpg) Some of these get big. I like the idea of flipping back and forth between the diborane and tetraborane to drop off or acquire hydrogens. [Answer] Not having any clue where to begin on the problem of reversibly binding methane in some kind of protein complex, I'd suggest an alternative route to carrying metabolic gasses entirely: straight-up solubility. Looking at your previous questions, it seems that your creatures are intended to use ammonia as a biosolvent. I have not been able to find solubility data on gaseous methane in liquid ammonia; if I had to guess, I would expect it to be slightly higher than the solubility of methane in water on Earth, since ammonia is slightly less polar than water and because the operating temperatures would be much lower (and/or the pressures would be higher). So, maybe you could get away with not bothering with a specialized gas transport molecule at all, and just letting methane diffuse directly into the blood plasma. If, however, that is unacceptable, methane is more highly soluble in various lipids and other hydrocarbons. So, you could rely on whatever the boron-based equivalent of a lipid micelle, with a non-polar interior, is to dissolve methane when exposed to air in the lungs, and then allow it to slowly diffuse out as the micelles pass by methane-poor tissues. ]
[Question] [ (My world's details) I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and fewer ocean depths. The world orbits a binary star system at a distance of the furthest region of the habitable zone, both of the stars having masses of 0.93x that of our sun's. The world is highly volcanic, approximately 15 to 16 times more volcanic than our planet. Surface gravity: 1.35x that of Earth's. Atmosphere density: 10x that of Earth's (a result of it being highly volcanic in comparison to earth.) Atmospheric composition: Nitrogen 78%, 15% Oxygen, 5% Carbon dioxide, 2% Trace gases. Temperature: Rather hot, the tropical regions being 90 to 110° Fahrenheit. (Based on what I've tested on Universe Sandbox 2) Land coverage: 75% water, and 25% land (but less water being present on this world as the oceans are shallower mostly due to a lot of island formations) Radius: 7750 kilometers Day/Night length/full rotation: 28 hours. Axial tilt: 53 degrees. Orbital period: 1.15 years Eccentricity: 0.025 --- I've heard that a denser atmosphere has more capacity for humidity compared to a thinner atmosphere with similar temperatures, is this true? Would a denser atmosphere hold more moisture even if the temperature was exactly that of Earth's surface temperature? --- (I seek more answers than just the four below, please answer if you can) [Answer] No In a mixture of gases, every gas behaves independently from others. That means that every gas has its own [saturation pressure](https://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressure) at a given temperature that is not dependent on total atmospheric pressure. You may have a pressure chamber or a vacuum vessel - in each case it will hold exactly the same amount of water vapor before it starts to condensate. [Vapour pressure of water](https://en.wikipedia.org/wiki/Vapour_pressure_of_water) [Answer] The absolute amount of water per cubic meter will have the same range as air on earth at the same temperature. This is because liquid water only evaporates until it reaches the saturated partial pressure for that temperature. It doesn’t matter whether it’s evaporating into 10atm, 1atm, or a vacuum. This means the mass fraction of water in the air is only 1/10th what it is on earth: same mass of water per cubic meter but a lot more air But that smaller fraction won’t have a big effect on your residents. What your planet’s residents feel is relative humidity: the fraction from 0% to 100% of that maximum possible absolute. 100% fells muggy because water can’t evaporate. 0% dries out your sinuses because moisture evaporated easily. 10x atmosphere isn’t terra incognito: divers routinely work at that and higher pressures. Humidity is just another thing to control in the breathing mix. The deep-water breathing mixes start out very dry because if they start with a typical 70% humidity partial pressure and then compress it into a tank, the compression raises the partial pressure too high (you raised all pressures by compression) and the water condenses. That in turn causes various downstream problems. Instead, they start with a small pressure of water that compressed is at the right partial pressure. Note another lesson from deep diving: oxygen at high partial pressure is a poison. Earth mammals can’t live at 1.5atm oxygen (10atm of 15%). [Answer] Moisture in the atmosphere is essentially a gaseous solution: water vapor into air. If you look at how the solubility is usually expressed, you see that the units are $mass\_{solute}/mass\_{solvent}$ or $volume\_{solute}/volume\_{solvent}$, or a combination of the two. Therefore if you have more mass of atmosphere available, you can dissolve more mass of water vapor in it at the same temperature. Intuitively, where can you dissolve more sugar? In a glass full of water, or in a bushel full of the same water? Yours is the same situation. [Answer] In terms of the actual mass of water in a given volume of air a higher pressure atmosphere holds more water at a given humidity but the actual humidity is based on the [partial pressure](https://en.wikipedia.org/wiki/Partial_pressure) of water vapour in the air that's a percentage ratio dictated by water's [saturation pressure](https://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressure) and won't change with alterations in overall pressure. Anything higher than 100% [relative humidity](https://en.wikipedia.org/wiki/Relative_humidity) is mist, fog, or rain depending on just how much water is available. Odds are that an atmosphere loaded with water vapour, carbon dioxide, and sulfur compounds from so much volcanic activity is going to have a constant acidic haze in the air made of Carbonic, Nitric and Sulfurous Acids, and water vapour. Moisture level will be almost permanently in excess of 100% relative humidity adding fog to the mix of noxious, opaque, gases. Any alien species, like humans, coming to the world you're describing will need serious protective equipment; the atmosphere is going to be pretty corrosive, even when it isn't the high humidity would cause clear air drowning as the over-wet air caused water to condense on the lungs, and the total pressure up at 1013.25 kPa is going to be like parking a car on everyone's chest. ]
[Question] [ In the [Time Crisis](https://tvtropes.org/pmwiki/pmwiki.php/VideoGame/TimeCrisis) series of games, terrorist-for-hire and recurring antagonist, Wild Dog has a cannon mounted in place of his missing left arm. Throughout the series, this weapon takes various forms such as a flamethrower, a rocket launcher, a grappling hook and even a tractor beam. Although, Wild Dog's personal favourite seems to be a multi-barreled Gatling gun (an M134 Minigun, if the [IMFDB](http://www.imfdb.org/wiki/Time_Crisis_3) is to be believed), which he uses in Project Titan, Time Crisis 2, 3 and 4. [![](https://i.stack.imgur.com/lA1Y7.png)](https://i.stack.imgur.com/lA1Y7.png) Project Titan [![enter image description here](https://i.stack.imgur.com/nZqL5.jpg)](https://i.stack.imgur.com/nZqL5.jpg) Time Crisis 2 [![enter image description here](https://i.stack.imgur.com/XGMxx.jpg)](https://i.stack.imgur.com/XGMxx.jpg) Time Crisis 3 [![enter image description here](https://i.stack.imgur.com/haxAd.jpg)](https://i.stack.imgur.com/haxAd.jpg) Time Crisis 4 Here are the weapon's specs, according to the [IMFBD](http://www.imfdb.org/wiki/Time_Crisis_II#Fictional_gun_arm): * Caliber: Caseless 7.62 mm * Weight: 5.2 kilograms * Length: 415 mm * Barrel length: 270 mm Would an arm mounted mini-gun be useful/practical? Why or why not? [Answer] Nope, not really all that practical. There are a few things wrong with the way the thing is depicted. For more info take a look at the wiki for[the m134 Minigun](https://en.wikipedia.org/wiki/Minigun) 1) You have a mini-gun that is capable of firing 6000 rounds per minute. That means you have to carry all of that ammo. Even if you update the thing to fire caseless rounds to save some weight, 6000 rounds is still going to be really heavy. Just the ammo, not counting the powder, primer, and chain linkage, would weigh more than 108 lbs. Add to that the motors needed to drive the barrels and firing mechanism. That will give you a bunch more weight. Then add to that you need a power source to spin the barrels. Even top notch Lith-Ion Batteries have substantial mass when you consider the power requirements. A Minigun, unlike normal machine guns, does not use recoil or gasses from firing to advance the next round. 2) You don't get to skate past Newton's 3rd law. Each round would generate around 10 foot pounds of free recoil energy. The rate of fire is such that you are firing 100 rounds per second! One shot from a .308 Winchester (the basis for the 7.62 nato round) can bruise the shoulder of a careless person. Repeated impacts at that rate is going to pound Wild Dog's stump to jelley, possibly causing tons of stress fractures to the bone beneath. 3) Heat. Those barrels get hot! [You can cook bacon on a gun barrel.](https://www.youtube.com/watch?v=V7UW5AkWqOY) The burning gunpowder and friction of the slug down the barrell heats these things pretty fast. Even a bolt action rifle barrel gets too hot to handle with bare skin after 10 rounds. That's after a slow pace, several seconds between shots. You are talking about 16.667 shots per barrel per second. Having some sort of 'gun arm' may be a fun idea. Something simple like a modified revolver or shotgun would be better for other reasons. Most firearms have mechanisms like magazine releases, trigger pull, safeties and so on that are designed for people with fingers. You would have to be doing all of those functions with the off hand. Loading up a box magazine would be a freaking nightmare with one hand. Re loading a revolver would be simpler, especially if you use a speed loader. Do it in the interest for quick draw capability, But leave the Mini-Gun on a truck. [Answer] It strongly depends on the setting / living conditions of the character. If having a gun at your hand is essential for day-to-day survival, having a gun arm might be an advantage. But otherwise it's damn impractical... Since ancient times people replaced missing hands with prosthetics or tools like hooks. That's because simple activities like preparing food or putting on clothes are extremely difficult with only one hand. A gun is not much help in that area. Furthermore, the human body needs to be in balance. Attaching a very heavy prosthetic to only one arm constantly pulls at the shoulder. Malpositioning, deforming joints and constant strain on muscles and senews would cause constant pain, often spreading to the neck and down to the hips. Technical limitations are another problem to consider. How much heat does a gattling gun produce? How can the heat be diverted from the body? Where is ammunition stored? The actual usability of such a gun is also questionable. To aim a gun you have to visually line up some kind of marking (scope, sight, notch and bead) with your target. Your arm-gun would have to be designed to allow visual aiming or be connected to an ocular implant to allow for computer aided aiming. I think in the end a hand-like prosthetic with an integrated (hidden) gun with limited ammunition would be realistic and could provide some interesting plots. Anything bigger would cause physical problems for the bearer and would make friendly interactions with strangers impossible ... Not to mention commercial flight [Answer] ## This gun would not be practical TL;DR: Recoil and pure weight would make this gun very hard to handle and inferior to smaller arms As other answers already covered the problems of the weight of ammo and heat produced, I will focus on recoil. All of the following data comes from Wikipedia and assumes the slowest fire rate of 2000 bullets/minute of the M134 Minigun. $F\_{recoil,M134} = 0.011 \text{ kg} \cdot \frac{2000}{60\text{ s}} \cdot \frac{853\text{ m}}{\text{s}} = 312\text{ N} \approx 7.7 \cdot F\_{recoil,AK47}$ So the recoil (nearly 8 times as high as that of an AK47 on full auto) of this thing will make it very unprecise and hard to handle, even when firing only in short bursts. Also as it seems he has the magazine mounted directly to the gun, which would weigh in at approxiately 7 kg assuming it is loaded with 200 rounds. Holding a total of 12 kg attached to the lower part of the arm when holding it in front of the body like seen in the images will also prove quite exhausting. Also delay and sound from spinning up will make it unusable for surprise attacks. The gyroscopic may also affect aiming but the effect should be negotiable compared to the issues with recoil. Here is a video of a minigun with supposedly similar specs being fired from the hip: <https://youtu.be/d84r8gMGxFQ?t=145> It can be seen that it is possible to fire it, but only with a solid stance and an external magazine for longer firing times. One could imagine a person carrying a 1000 round magazine in a backpack and and the gun on the hip like in the video but the low mobility due to weight and bulk would make this still an easy target. ]
[Question] [ This question already has answers here: [Plausibility of the Japanese Nekomimi](/questions/58878/plausibility-of-the-japanese-nekomimi) (8 answers) Closed 3 years ago. This is a submission for the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) Fantasy worlds from Asian novels (and related media) have lots of [kemonomimis](https://tvtropes.org/pmwiki/pmwiki.php/Main/LittleBitBeastly?from=Main.Kemonomimi). They are human-ish species that have animal ears and tails. Of the fox, wolf, cat, bear, raccoon, dog, lizard, and so on. ## Ears: Sometimes they are depicted with both human and animal ears, but we are ignoring this type. What is the anatomy of those ears? Where in the kemonomimi skull are the ear orifices located? --- ## Tails: How much can their tails bend at the junction to the body? Can they use human furniture, like chairs normally, or do they need a hole/side opening for the tail? [Answer] This is an interesting question. I would like to preface my answer with I am not a biologist so this answer may be no more than educated speculation. That being said, let's get into it. A key thing to note here is that animal people anatomies would have to vary significantly. Many mammals have similar senses to human, but something that I saw mentioned is lizard people. Many reptiles simply don't have ears. That's not to say that they don't have eardrums, just that ears don't necessarily appear. Animal senses are not always consistent with the human senses so that makes this question particularly challenging in some regards. However, by examining skulls of both human, and other animal species, it can be seen that regardless of ear positioning, the hole used for "wiring" the eardrum, is found at the base of the jaw bone. This leads to a highly likely interpretation that a kemonomimi would have similar if not the exact same ear channels. However, the other consideration is skull shape. Ears seem to require an indent into the otherwise convex skull. If the ears were to be positioned on top as seen in various media, it would require a weird skull indent that isn't commonly, if ever, seen. This could produce a decrease in brain function as well as mechanical stability issues. It seems that the ears on top of the head would require a certain spacing to help decrease these issues. However, after examining media it seems almost perfectly optimized, especially in the case of cat people (sometimes referred to as kemonomimi). A side channel or indent along the skull would allow for the best configuration. As for tails, again based on media, we can see that they seem to be placed at a well-optimized location. Roughly 2 to 3 vertebrae above the tailbone assembly is the best location. I would envision a vertebra that has a junction in a v-shape allowing for an additional connection. It is reasonable to expect that the tail could bend about as much as it does currently on animals as the mechanics of it scales very nicely. That being said, keep in mind that many animals have the tail more in-line with their spine so it aids in initial angling of the first tail vertebra. Assuming this is true, there is little reason to believe they couldn't sit in a chair. If you notice, in chairs, typically, there's a small gap between a midsection of your spine and the bottom of the chair. For smaller tails, there would be no issues in allowing the tail to rotate to the side. Larger tails, like that portrayed in Spice and Wolf, there could be issues, all of which are ignored to my knowledge in the books and show. Hopefully, that's enough information and makes sense. Feel free to refute anything I said as it may be wrong [Answer] The ears developed from part of the jaw, so the ear canals can't be much above the jaws. The way real cats have their ears on top is they funnel the sound down to a place right about where the human ear canal is. So presumably your creatures would work like the real ones do. The ears would go wherever they work best, and they would connect to ear canals in the usual place for mammal skulls. It just isn't that different. [Ear picture](https://breedingbusiness.com/wp-content/uploads/2017/02/dog-ear-anatomy-800x923.png "ear picture") I was real unclear how to find a scientific answer for dog-tails on humanoids. I reasoned like this: If the creatures are humanoid, maybe their tails will be kind of like primate tails. So if I can find pictures of monkeys with tails sitting in chairs, that will be more convincing than pictures of actual dogs or raccoons sitting in chairs in their own non-humanoid ways. So I looked for pictures of primates in chairs, and I found nothing but chimpanzees. (Incidentally do NOT google for "monkey rocker".) But many pictures of tailed monkeys sitting on flat surfaces convince me that their tails are quite flexible. At least some species can sit straight with the tail not in the way, turning beside them at a relatively sharp angle. The best pictures I found were stock photos that I can't copy, but here's one. [sitting monkeys](http://cdn.shutterstock.com/shutterstock/videos/17777578/thumb/1.jpg) I think for purposes of story-telling, it would be reasonable to have tails that allow sitting in most chairs. There would be enough chairs incompatible with them that if they are given one that doesn't work it would not necessarily be on purpose, but it would be reasonable to suspect it was on purpose. I can't guess about lizard tails. They are very different. Should a kemonomimi lizard tail break off and wiggle around to let the kemonomimi escape easier? The others are all similar body plans. It's just little differences in shape. Lizards are more different, and it's harder to guess how it might reasonably work. ]
[Question] [ The 12 planets in my solar system orbit the G-type star of Nemo. It's about nine-tenths of the size of the sun, and has a stellar luminosity of 0.67 L☉, a diameter of 1.28 million kilometres, a surface temperature of 5,980 degrees Kelvin and (Starting from its birth) will live for 13 billion years. I mentioned that there are twelve planets in this system. The 4th one from Nemo is habitable and the 8th one is the system's largest gas giant. The respective distances of all these planets from Nemo are shown below. --- Starting from Nemo's solar mass, I was able to work my way up and build the solar system to that point, maintaining plausibility. Now that I know how many planets there are and where they are, how do I know what kind of planets they are? Which ones are gas giants, which ones are rocky, how big are they? Are some clouded over like Venus? These are all questions I need to answer to complete the construction of the solar system and move on to the habitable world. Here are the distances of the planets from the star: --- Inner limit: 0.09 AU, First planet: 0.17 AU, Second planet: 0.32 AU, Third planet: 0.45 AU, Habitable zone inner limit: 0.72 AU, Fourth planet: 0.86 AU, Habitable zone outer limit: 1.03 AU, Fifth planet: 1.63 AU, Sixth planet: 2.30 AU, Seventh planet: 3.30 AU, Frost line: 3.94 AU, Eighth planet (Gas giant): 4.95 AU, Ninth planet: 6.97 AU, Tenth planet: 9.98 AU, Eleventh planet: 15.96 AU, Twelfth planet: 28.1 AU, Outer limit: 36 AU --- Sorry, that was probably a slog to read through, but I thought I'd include those statistics should they be important for answering this question. Any other figures you require about the star Nemo are shown in the first paragraph. Now, the question in full: How do I figure out what kind of planets these bodies are, or is it even possible? What factors influence this; distance, temperature, or something else? Are there any other important things to consider? You don't have to build the whole system for me, I'd be fine with just equations to do it myself. --- Answerers, please note: I am not an astrophysicist, nor am I a wizard of mathematics. If you're including very complex terminology in an answer which I can't find the definition of without trawling through a Wikipedia page, then it'd be appreciated if you could explain them. Also, I'm just as capable of performing (But not always forming) equations myself, but please present equations (If they are relevant) in a way that would be comprehensible to the layman (Who can do maths and knows a lot about biology). If you need more details about the star and its system, please ask me and I will add that in and notify you. Others, please note: If you have objections of implausibility, please put them in the comments - and as soon as possible. While the project is young is the best time to point out weaknesses. If you think this question is broad, unclear, or off-topic, please say so, and I will amend the question accordingly and promptly. If you feel the need to downvote the question, by all means do, but I beg that you say why. Downvoting without critiquing isn't very helpful. [Answer] # Massive objects beyond the frost line are likely giant planets. Let's talk about the [frost line](https://en.wikipedia.org/wiki/Frost_line_(astrophysics)), which you helpfully specified (3.94 AU). For anyone not familiar with the term, the frost line is the distance beyond which - in the protoplanetary nebula, while the system was still forming - heavy elements we call [volatiles](https://en.wikipedia.org/wiki/Volatiles) could condense into solid grains. These small bits of solid matter could then clump together into larger conglomerates, which in turn made it possible for larger [planetesimals](https://en.wikipedia.org/wiki/Planetesimal) to form. This in turn encouraged the formation of giant planets. The same thing doesn't happen inside the frost line, meaning that smaller protoplanets formed, and their growth was limited. They would eventually become the smaller, less-massive terrestrial planets. There are some exceptions to the rule; [Hot Jupiters](https://en.wikipedia.org/wiki/Hot_Jupiter) are giant exoplanets found orbiting extremely close to their parent stars. However, these giant planets likely moved to their present locations via [planetary migration](https://en.wikipedia.org/wiki/Planetary_migration), which could have happened in a number of ways: * Through interactions with the protoplanetary disk * Through interactions (scattering) with other planets and protoplanets * Through interactions with gas nearby The system here has 12 planets - more than any known planetary system. I find it unlikely that any giant planets could have stably migrated inwards without disrupting the system. Assuming giant planets can only form beyond the frost line, then, we conclude that the inner planets (1-7) are terrestrial. --- # Calculating the frost line The radius of the frost line changes with time, increasing as the star becomes more luminous. For instance, I believe the Sun's current frost line is around 5 AU, whereas when the Solar System formed, it was around 3 AU. The flux from a star drops off as $r^{-2}$, so I would argue that the relationship between the radius of the frost line and the luminosity of the star should go as $$r\_f=r\_{f,\odot}\left(\frac{L\_\}{L\_{\odot}}\right)^{1/2}$$ where $r\_{f,\odot}$ is the Solar System's frost line radius, and $L\_\$ is the luminosity of the star. I thought I had found a formula of that sort in [Hayashi (1981)](http://adsabs.harvard.edu/abs/1981PThPS..70...35H), but looking back, I can't find it. Now, you've said that $L\_\\approx0.67L\_{\odot}$, so we find that, at the present time, $r\_f\approx2.2\text{ AU}$ - much less than your value of 3.94 AU. Plus, the young star would have been even less luminous than the Sun. A value of perhaps 1.5-1.75 AU is more realistic, meaning that only planets 1-4 would be terrestrial. --- # Stellar parameters I also want to do a quick reality check of sorts on your star. Stars are pretty good [black bodies](https://en.wikipedia.org/wiki/Black_body), which is a thermodynamic term describing how they absorb and radiate radiation. We can use something called the [Stefan-Boltzmann law](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) to calculate the luminosity of a star if we know its radius ($R\_\$) and temperature ($T\_\$) using the Stefan-Boltzmann constant, $\sigma$: $$L\_\=4\pi\sigma R^2T^4$$ Plugging in your parameters for radius and temperature, I find that for your star, $L\_\\approx3.88L\_{\odot}$ - much* larger than you calculated. I would recommend reducing the surface temperature to about 4,000 K, and similarly reducing the radius to achieve the desired luminosity. This would make it a [K-type main sequence star](https://en.wikipedia.org/wiki/K-type_main-sequence_star). --- # Orbital resonances The largest exoplanetary system we know of is [Kepler-90](https://en.wikipedia.org/wiki/Kepler-90), with 8 planets. It's pretty compact, with all 8 planets being within 1.01 AU of the parent star. I'd like to note that some of the planets have fallen into stable [orbital resonances](https://en.wikipedia.org/wiki/Orbital_resonance). Essentially some of their orbits are in integer ratios of one another. We see the same thing in some of the moons in our Solar System. In the large and complex system you're describing, I'd also expect some of the planets to be in orbital resonances. If you care enough to calculate some stable ones, you can do that (note that not all resonances are stable). Also, on the subject of Kepler-90, I'd like to mention that the outer two planets are in fact giant planets, and they're likely inside the frost line. That's an interesting twist; perhaps giant planet migration is indeed possible. That said, it's also possible that Kepler-90 was significantly dimmer in its past, or that the migration of these two planets resulted in the scattering of other former planets, now gone. We don't know for sure. ]
[Question] [ I am creating a planet where life exists on big islands of frozen methane around the poles. I did some research: from what I understand, methane freezes around -180°C, so I wanted it to be -190°C (this is because I don't want it to melt during summer). Is intelligent life possible at temperatures this low? [Answer] You might have to stretch the meaning of "intelligent life". The energy levels at 80 K are pretty low but not zero, so you could have some kind of chemical system. Would that system be complex enough to support life? We're not even all that sure about what life is, but it looks quite likely that it involves complexity. At least the kind of life that evolved itself until now. Just like computers, you need a certain number of types of logic gates and connections before "electronics" might become "computing". Going cold-wards, the chemistry would be much simpler than ours (the number of possible reactions between chemicals starts from zero at absolute zero, increases as the available energy exceeds the activation energy of more and more chemicals, reaches a peak somewhere, then falls off again as the ambient energy level at higher temperatures exceeds the stability of most substances). Would the chemistry become so simple that a biochemistry isn't possible? At least in theory, [what you lose in configurational complexity you might compensate for with speed and spatial complexity](https://xkcd.com/505/), provided you kept above the unknown "sufficient basic complexity" threshold - a sort of Turing-completeness for chemistry that turns it into viable biochemistry (thanks to @Raditz\_35 for pointing this out). Your sub-zero beings would probably need to be huge and sluggish, moving at a (literally) glacial pace. They would be weaker and would almost surely need a much lower gravity. At higher temperatures than yours, you could try using ammonia instead of water and still get a "earth-like" biochemistry, in that ammonia is also polar and has comparatively high latent heat. Hal Clement, among others, experimented with that idea (I think that Mesklin, Tenebra and Enigma-88 all have some lower-temperature biochemistry going on). At lower temperatures, the biochemistry would be completely different and I wouldn't even try to describe it. Liquid methane, ethane and other hydrocarbons are not as good as water or ammonia because they're not polar substances, but I wouldn't try going into the gory details: most readers wouldn't be able (or happy) to follow them, and unless you're into cold (bio)chemistry, those that could would probably be irked by the inevitable errors. [Answer] Life as we know it is based on water. Water is used as solvent for carrying on the gazillions of chemical reactions involved in what we call life. Water freezes at $0^o$C, or somewhere lower if something is solved into it. This means that once water is frozen there is no way to have those reaction take place. No life related reactions = no life. You might object: what about a form of life not based on water but on methane? Again, solid phase reaction are normally slower than liquid phase, so if any life was possible based on methane, it would suffer. [Answer] One question to ask, does the life need to evolve there? For a robotic/AI life, a frozen planet might actually be desirable as it could allow greater processing power and more efficient cooling. [Answer] We aren’t sure the definition of intelligence yet, but if the Turing Hypothesis is true (that human intellect is equivalent to a sufficiently complex Turing Machine) then, yes, intelligent life is possible at those temps. Turing complete operations have been demonstrated in ridiculously simple systems with very low energy requirements. The thoughts might be realllllly slow, but it seems possible. [Answer] Could human intelligent life survive -190C? Intelligent life does not need to wear a Speedo outside on your cold planet. It will do what it needs to do to survive. The easiest way to have intelligent life on your cold planet is to have whatever sort of intelligent life suits your story, and then have it use its intelligence to survive on your cold planet. Your intelligences can be from somewhere else, and they reside on the planet for their reasons. They have technology they use to stay warm. Or not. I could imagine that an intelligence based on electricity might find very low temperature situations / superconductivity conducive to their kind of life. [Answer] In the Orion's Arm universe, there is a methane-ethane based species called the Muuh. They have ice ships made from comets. They are slow, but then the Muuh are slow beings. Here's a write-up for the Muuh Ice Ships for you to peruse: <http://www.orionsarm.com/eg-article/49773331d6471> ]
[Question] [ I'm building a world which has, apart from the 'usual' stuff, 2 types of stones (haven't really decided on a name yet). 1. Stone A holds some form of energy but when prompted by Stone B it will release its energy in some form of light. To charge this stone, one can either put it in direct sunlight or have it absorb enough of Stone B to charge it up to a certain threshold. So this stone is rechargable to give light more then just 1 time. 2. Stone B also holds energy. But rather then light it will give of some other kind of radiation (or anything undetectable by human eyes). This stone functions as a catalyst to trigger the reaction in Stone A to illuminate. This stone might be depletable. Favorably the radiation given could be used for other purposes then just trigger the reaction in Stone A. When I was figuring this out I did a lot of handwavingand and would like to reduce this to a minimum (but there might still be involved). In my world I would like to give these stones all kinds of appliances. Maybe as a flashlight or a weapon or a microwave or a streetlight, maybe things I haven't thought of yet. Long exposure to any stone in relative small doses should be non-lethal to humans. Though if usage might cause harm that is just fine. What I am looking for is a way to describe the relationship and reaction between the 2 types of stone. Preferably also the reasons why it would work as I described (in the appliances I would like to use them for). And perhaps it already exists in the real world somehow? --- EDIT: The details provided are not fixed yet. So if you feel like something feels off feel free to interpret them to make more sense. But the less you need to change the better. Details provided how these stones would work in the example appliances would be highly valued. [Answer] If stone A is an electrical conductor, and stone B is a magnet, you can use your duo to create electricity. Moving the magnet (and associated field) past the conductor will induce an electrical current within the conductor. The electricity can be used to light a light or do other work., <https://makezine.com/projects/make-41-tinkering-toys/induction-instruction/> [![electrical induction](https://i.stack.imgur.com/fCHYh.jpg)](https://i.stack.imgur.com/fCHYh.jpg) This is how electrical generators work in real life. In real life you have to keep the magnetic field moving, which means moving the magnet. For your world: imagine stone B is a substance in which the constituent subatomic particles can be spun up so the magnetic field rotates without the magnetic stone itself rotating. You could hold it still in your hand and its field would spin around it. You would not notice this. But if you held stone B near the conductor stone A, the induced current in stone A would drain the spin energy from stone B until the magnetic field stopped moving, at which point no more current would be induced. The magnetic field is your invisible radiation. The spin energy is the deplorable aspect. Alternate use: Stone B could also ring a bell very fast if held next to a magnetic ringer, which would be alternately repelled and attracted by the spinning magnet. If the spin was really fast it would be more of a buzzer than a bell. You can attribute the spinning magnetic field effect principle to something involving proton spin, which invokes dense particle physics incomprehensible to most. The few who do understand will have a good laugh. <https://en.wikipedia.org/wiki/Proton_spin_crisis> [Answer] Yes, it is realistic. Something similar exists, and it is actually used to measure the age of certain stones: it is called [thermoluminesce](https://en.wikipedia.org/wiki/Thermoluminescence). > > High energy radiation creates electronic excited states in crystalline materials. In some materials, these states are trapped, or arrested, for extended periods of time by localized defects, or imperfections, in the lattice interrupting the normal intermolecular or inter-atomic interactions in the crystal lattice. Quantum-mechanically, these states are stationary states which have no formal time dependence; however, they are not stable energetically. Heating the material enables the trapped states to interact with phonons, i.e. lattice vibrations, to rapidly decay into lower-energy states, causing the emission of photons in the process. > > > Thermoluminescence is a common geochronology tool for dating pottery or other fired archeological materials, as heat empties or resets the thermoluminescent signature of the material > > > Stone A in this case would be the pottery, while stone B would be a naturally radioactive stone. You need only to add heat to release the luminescence. ]
[Question] [ Next question about kinetic weapons in my universe: We have a coilgun/railgun, it launches a projectile at 30 km/s; if it meets a compartmentalized spacecraft on its path, does the projectile go straight through the hull, or blow into schrapnel/plasma just after hitting ship? If not either of the above, what does happen? What I mean by compartmentalized spacecraft: instead of one propellant tank, there are many, and in between them armored crew sections are sandwiched. All of it is divided by bulkheads, and external envelope of the ship is light armor capable of stopping small space trash and meteors. Additional information: The projectile material is tungsten, ships are mainly made of something strong and light, i.e. good steels, titanium, some composites maybe. Projectile can pierce the armor used in crew sections if it is still intact after going through rest of the ship (which I am trying to determine). Anti meteor armor is a Whipple shield with two thin layers of light metal. [Answer] I highly recommend fully reading through the following [link](https://www.esa.int/Our_Activities/Operations/Space_Debris/Hypervelocity_impacts_and_protecting_spacecraft). Most of the research on hyper velocity impacts looks at objects traveling at about half your projectile speed because about 15km/s is the most we expect to need to worry about in regards to small debris. However, [Whipple Shielding](https://en.wikipedia.org/wiki/Whipple_shield) is highly effective at stopping small impactors at hyper velocities. If you look at [figure 4-2](https://www.nap.edu/read/5532/chapter/6#31) at that page, you will see that the effectiveness of the Whipple shielding on the ISS drops off at higher velocities, but should still be at about half effective at the speeds we are talking about (also, what might be important for story purposes, Whipple shielding is actually shockingly ineffective against projectiles at around 2km/s (though more traditional shielding is usually behind the Whipple shielding). Impacts against Whipple shielding will produce clouds of plasma as the impact material (and shielding) disintegrate. While this won't cause damage, but it can mess with electronics. Something important to note about this. Whipple shielding testing is done with Aluminum spheres with a diameter between .5-2 cm. Larger projectiles have more energy (though only linear, unlike the quadratic increase from velocity). This [video](https://www.youtube.com/watch?v=Dqjq-LQgGDk) shows the impact of a small (4mm) hyper velocity projectile hitting a non-pressurized tank in a vacuum. You can see the blast of plasma and shrapnel that fly out. The wikipedia page for [Hypervelocity](https://en.wikipedia.org/wiki/Hypervelocity) has a pic of more traditional shielding. For reference it is 18 cm thick and the projectile is 1.2 cm. High velocity impacts cause the materials to behave as fluids because materials can behave like fluids under high stress. This [page](https://ares.jsc.nasa.gov/orbital_debris/hvit/impact/impact-physics.html) has some useful areas showing you what damage can occur even when not catastrophic. You can end up with what is called "detatched spalls." Internal fracturing of the material could cause shrapnel even if the material itself was not penetrated. [Here](https://hvit.jsc.nasa.gov/shield-development/shield-development-materials.html) you can read more about the materials used in shielding, and [this](https://hvit.jsc.nasa.gov/shield-development/shield-development.html) will let you compare different shielding styles (Whipple is just what is used on the ISS). This [paper](https://pdfs.semanticscholar.org/d29a/f7164b012d6aa132333d658805953140674d.pdf) includes some useful graphs that you can use to extrapolate penetration depth. But what will happen with a larger projectile. NASA and the ESA quote "catastrophic failure" for 10cm projectiles. But what happens to the projectile. Unfortunately your question falls outside of what people typically will test. Spacecraft shielding typically is tested against small impactors. Larger impactors tend to be tested against rock (for cratering of moons). I am assuming your projectiles are going to be larger than 10cm? I can say for certain it won't be fully intact. You will get some plasma and some shrapnel. Will your projectile continue in to impact more things? It's hard to say without knowing more. If you give me an approximate projectile size and armor thickness, I can run a simulation for you and get back to you with "nice" pictures and edit my question, but with the details as given I think my answer is suitable. If you want to run the simulation yourself, I would recommend [gizmo](http://www.tapir.caltech.edu/~phopkins/Site/GIZMO.html). Actually [iSale](http://www.isale-code.de/redmine/projects/isale/wiki/Terms_of_use) would be even better / easier. One of their examples is exactly what you need as long as you tweak the projectile size and speed. However, you would need to contact them to get permission to run it. [Answer] According to the wiki and other sources I cant be bothered to look up right now (if only because I cant remember how or where I found them in the first place), at, or above, a certain velocity metal will act like a fluid upon impact. <https://en.m.wikipedia.org/wiki/Hypervelocity> Now it doesn't matter which is moving, both the projectile and the target will experience this. So upon impact both will deform. Additionally, the impact will accelerate the pieces the projectile comes into contact with and turn its 30km/s velocity into energies like heat. So the question would need some info about the projectiles weight, density (I don't think we'll get accurate data on how most materials behave at Hypervelocity impact) and shape of the projectile that contacts. The formula for kinetic energy has the square of velocity times mass, which means higher speeds builds kinetic energy faster than more mass and 30km/s is a lot. If the projectile is relatively small it would impart 100% of its energy into the target causing essentially an explosion consisting of the projectile and the parts it came into contact with, which isn't going to be pleasant. If it is larger it wouldn't lose all its kinetic energy on impact and drill through the ship, causing fragments of what it smashes through to spiral through the ship. It might be better to put less armor on and make sure the projectile just tears a hole through the ship as less total energy is imparted, as you can quickly reach nuclear explosion strength kinetic energy that you need to dissipate if you try to stop it with armor. [Answer] > > If not either of the above, what does happen? > > > Ricochet. You have 2 options which can happen: projectile traverses target at same trajectory retaining kinetic energy, projectile explodes on / into target expending kinetic energy. The third option is that the projectile hits the target, expends a little bit of energy and continues on at a reduced speed and a different trajectory. The Brad Pitt tank movie has a lot of gore but excellent tank battle scenes including many where a shell bounces off of a tank's armor - Brad's crew bounced several off of heavily armored German tanks. Check Youtube. So to your ship. I think tank armor is angled for this reason (correct me if this is wrong, commenters). In space, it seems to me the best armor shape for this would be very long very hard conical spikes. Unwieldy on land but fine in space. An incoming round would encounter the side of a spike and tend to ricochet off trajectory, missing the ship. Needless to say this spike ship would be immensely bad of ass, bristling with spikes, many of them broken / fused / scratched silver from prior deflections. ]
[Question] [ Consider an area of a fantasy world which experiences the following changes: * Amount on rainfall, and thunderstorms, increases dramatically. * Average temperature increases by 10-20 degrees Celsius over a period of two years (depending on how cold the location originally was; there is some variance in the temperature of the region). What happens to forests, fields and livestock? Will the place be a decaying apocalyptic wasteland (with forests and fields rotting where they used to grow, and livestock and game animals dying of exhaustion), or will there be enough crops and remains of an ecosystem for people to survive without a significant loss of population? In the long run species more adapted to the new climate will certainly take over, but I am more interested in what happens within the transitory period; up to five years, for example. A climate change of 2 degrees is considered to significantly change agriculture; a change one order of magnitude will do more. On the other hand, many animals can survive such a change (some people take a vacation in the sunny south during the coldest winter, for example), if they have something to eat. I do not know about plants. # Details Before the changes above, the area is a more-or-less stereotypical fantasy setting - flora, fauna and climate are roughly similar to central to northern medieval Europe, as is culture. There is lots of uninhabited woodland and hills. The population is fairly small and scattered; this is a backwater of a larger civilization. The area is limited by mountain ranges, a desert, and a large swampland, where the temperature gradually changes from the previously abnormally cold to that of the surrounding areas. # Context I'm running a fantasy roleplaying game, and due to a powerful nature spirit leaving and another filling the power vacuum, the mentioned environmental effects happen. These forces do not otherwise actively change the life of living things in the area. There is other magic, but I am not interested in what effects it might or might not have. I want to know what will happen if none of there powerful unrealistic forces take notice and act. (In the context of roleplaying, this will give the player character room to do something about the events, or to ignore them, as they will, and with consequences.) [Answer] There is a lot of difference between 10° C and 20° C. Let's take as a starting point [Stockholm](https://en.wikipedia.org/wiki/Stockholm) in Sweden: average temperature 7.6° C, average low 4.5° C (from −3.9° C in February to 14.5° C in July), average high 10.7° C (from 0.5° C in January to 23° C in July); it rains all year round, with a total of 531 mm/year. (One wouldn't think of it as such, but Stockholm receives less total precipitation than [Rome](https://en.wikipedia.org/wiki/Bucharest) and even [Bucharest](https://en.wikipedia.org/wiki/Bucharest).) ## 10° C warmer Consider [Naples](https://en.wikipedia.org/wiki/Naples) in Italy: average temperature 15.9° C (8.3° C warmer), average low 11.0° C (from 4.4° C in January to 19.1° C in August), average high 20.8° C (from 13° C in January to a whopping 30.3° C in August); it rains from September to April, with a total of about 1,000 mm/year (twice as much as in Stockholm, but the summers are drier). While the spontaneous flora is quite different it is not entirely different, and Italians can grow all the plants Swedes can grow, plus some which won't grow in Sweden. Overall, a 10° C warming going from the climate of Scandinavia to the climate of Italy would be survivable, and, as a bonus, people will have the opportunity to grow grapes and olives and oranges. ## 20° C warmer Consider [Jakarta](https://en.wikipedia.org/wiki/Jakarta) in Indonesia: average temperature 26.7° C (19° C higher), average low 23.3° C (year round), average high 30.1° C (year round); it rains all year round, with a total of 1,816 mm/year (3 times the amount of rain which falls in Stockholm). There is very little in common between the spontaneous or cultivated plants of Scandinavia and Indonesia. Some of the plants which grow in Sweden can also be grown in Indonesia, but many cannot cope with the excessive humidity. A quick warming of 20° C would need very careful management for the country to cope; without careful and active management the country will descend into chaos before reorganizing itself. Most of the plants won't be able to survive; if there is enough rain, new plants will take their place. Many crops won't make the transition; new crops must be substituted, again if there is enough rain. ## Warmer places need more water As we have seen, Stockholm gets only 531 mm if rain per year, whereas Naples gets about twice that; and yet, Naples does not look wetter than Stockholm, quite the contrary. [Algiers](https://en.wikipedia.org/wiki/Algiers#Climate) on the northern coast of Africa gets just a little more rain per year than Stockholm, but it definitely looks parched compared to the capital of Sweden. That's because warmer climate induces more evaporation, including [plant transpiration](https://en.wikipedia.org/wiki/Transpiration). Increasing the temperature with an average 10° C while keeping the same amount of rain would transform Sweden into northern Africa, a region where agriculture is possible but quite difficult and anyway very different. Increasing the temperature 20° C while keeping the same amount of rain would transform Sweden into an outright desert. [Answer] Plants by themselves usually handle warmth and moisture very well. In the short term, most of them would thrive. Over the next few years, there would be massive ecological changes as some plants out-compete others in the new environment. Your world is going to get devastated by storms, though. If your world is heating up and 1 degree a month your atmosphere is going to be incredibly turbulent. You are going to see Cat 5 hurricanes, tornadoes, the works. Anything that's not bolted to the ground - and a lot of things which are bolted to the ground are going to get uprooted. Other areas are going to see massive flooding. [Answer] I think it really depends a lot on the lay of the land. If the rainfall increases a lot then low areas with poor drainage would become bogs/swamps. High, well drained areas would probably thrive. [Annual plants might become perennials](https://www.quora.com/Will-annual-plants-grow-year-round-in-subtropical-climates), since the warmer winters could keep them from dying off completely. Some of the summer plants might turn into winter plants, if the summer heat is above their threshold. Crop cycles would change a lot. You'd be able to plant earlier, harvest later, meaning that you could have several growing seasons each year. Depending on the winter temperature, [you could potentially grow some crops year round](http://homeguides.sfgate.com/grow-vegetables-yearround-warm-climate-69606.html). The increated rain would help, but likely they'd have to import some plants/seeds from more tropical areas as the temperate/dry loving plants died off. Mosquitoes and other hell spawn would become a bigger problem since there would be more standing water and less chance of cold killing them off. This could affect cattle. [Answer] A couple of years are not enough for evolution to happens. Plants which are highly sensitive to environmental conditions would likely largely suffer or even disappear from their original regions. I.e. a cactus or an orchid do not handle well quantities of water outside their comfort zones. More "relaxed" plants may still thrive or even grow better. But at this point you also need to check how the environmental condition affects the reproduction assistants of the plants: * intensive rains may affect the ability of some anemophile plants to spread their pollen * bees and insects may suffer from altered climate conditions. Livestock, depending on plants for foraging, will be affected, especially those relying on open grazing. However, being this aspect influenced by the humans, it can be mitigate by importing new types of plants. [Answer] With a temperature increase of 20C, your whole weather system will, in exact scientific parlance "Go Nuts" Expect tropical storms to be about 5 times more frequent, and about 30 times as intense as before. No, that is not a typo. Thirty. three-zero times. Plantlife.. Assuming it gets sufficient moisture, most plantlife will survive adequately in the short term. Thrive, even. Expect seeding patterns to be utterly disrupted. After a while, expect fungal and bacterial infections to also "Go Nuts". Insect life will suffer horribly, but some species will thrive. Higher animals will die in droves. Especially mammals and birds simply could not survive such a massive change in such a short time. Consider a simple example, close to yourself. Adding 20C will make NewYork hotter than Dubai is, currently But the situation will be temporary. If the plantlife does not get sufficient moisture, OR if the plantlife dies out due to thermal shock OR if the plantlife flourishes, then chokes itself.. Creates continent-wide bonfires just waiting to be ignited. Expect some serious smog for the next few decades. And all those are the short-term consequences. Adding 20C to the whole planet, then burning all surface plants life, will release a ludicrous amount of CO2 into the atmosphere. Heating the ocean by a similar amount will reduce its capacity to carry CO2, causing about a third of the dissolved CO2 to enter the air. This double blow will leave you with a climate bouncing like a yo-yo, but trending to stabilize eventually with a temp increase of 50-80C. Byebye all life, even microscopic life. ]
[Question] [ In my story interstellar travel is common, but nothing's perfect, and a mining ship returning from a deep-space run (you'd be surprised what's out there) just discovered that something is very, very wrong. ``` \crackle\ Mayday... Mayday... this is the Tycho Brahe... Primary engine offline. Asteroid impact in the Oort cloud. Request assistance... over. \squeal\ Tycho Brahe... this is Sol reference Alpha. What is your vector to the initial... over. Sol Alpha, Tycho Brahe, solar declination +23¬∞, right ascension -87¬∞, Delta-forty-alpha, Victor-five-charlie. ... Sol Alpha, Tycho Brahe, are you still there? Tycho Brahe, Sol Alpha, negative on assistance. Repeat, negative on assistance. Recommend deploying solar sails and maintain vector to the initial... over. ``` Question: Given 40 Km2 solar sails (and ignoring necessary support structure), is it possible for a ship with a mass of 5,000,000 Kg traveling at 0.05c at a distance of 40AU from the sun to deploy those sails and, using only the solar wind, decelerate to 250,000 Kph before crossing the "orbital sphere" of Mercury? --- Solar Declination & Ascension This doesn't actually have anything to do with the question, but just for fun and off the top of my head (please let me know if I've plagarized a published story!), I defined the reference for solar declination and solar ascension as measured from the line drawn from the center of the sun to the center of the galaxy and otherwise used in the same way Astronomers use declination and ascension. It eliminates the position of the earth from the equation (making the reference static and applicable by math to any body in the solar system ... or any solar system). Thus, "Vector to the initial" would always be your position and speed in relation to an approach toward the center of the sun. If I haven't plagarized from somewhere... I thought of it first! üòÄ Victor-five-charlie Also for fun, an over-the-radio way of saying "my velocity (victor) is 5% or 0.05 of the speed of light (charlie)." The percentage is always assumed. Delta-Forty-Alpha Ditto, the distance from the sun along the indicated vector in "alpha" or AU. Vector to the Initial Yes, I'm not using this in the same way today's pilots do. Orbital Sphere Out of curiosity, do astronomers today have a phrase that identifies the sphere enclosing a radius from the sun equal to a planetary orbital distance? [Answer] Edit: I did make a math error, the points below still stand though. No. The solar wind pressure simply isn't strong enough to stop you. Making larger sails would increase the force applied to your ship, but would well surpass known material shear strengths and would destroy itself. Assume a constant acceleration for simplicities sake and we can use: $DeltaX = 1/2\Acc\Time^2 + Vel\_{initial}\time$ $Acc = (Vel\_{final} - Vel\_{initial})/time$ Rearranging those gives us $Acc = (V\_f-V\_i)\(v\_f+v\_i)/(2\deltaX)$ Using $V\_f = 250,000 KpH = 67444.4 m/s$ $V\_i = 0.05\c = 0.05\3\10^8 =$ ~~45,000,000~~ $15,000,000 m/s$ $DeltaX = 40 AU = 40\149,597,870,700 = 5,983,914,828,000 m$ We get an acceleration of ~~-169 m/s^2, or about 17 g's.~~ $18.8m/s^2$ or 1.9 g's Humans can't really survive more than a couple g's for extended durations. This example is assuming a constant acceleration, which is even worse for our real life use case. The solar flux is going to fall off with the inverse square law over distance, so at 40 AU it is going to be ~1600 times weaker than it is at 1 AU. Achieving 17 g's of average acceleration over our distance will require a gentle deceleration at the start of our journey and a massive amount of force near the end as the solar wind density increases. This will absolutely shatter any plausible sail support structure and kill your crew. ~~0.05 c is probably too fast for any inhabited ship to decelerate from in 40 AU.~~ Uncomfortable but survivable. ~~If you can take it down by a factor of 10, to 0.005c, then the required average acceleration is -0.187m/s^2, which enters into the realm of plausibility for a large enough sail.~~ -0.187m/s^2 is still way outside the realm of plausibility for our situation. Addendum: So the numbers above are a bit off, and our required acceleration would be survivable, so I decided to run even further to see what the necessary pressure from our solar wind would be.* $Force = mass\Acc$ $Pressure = Force/Area = mass\Acc / Area $ $Pressure = 5,000,000kg \* 18.8m/s^2 / ( 40\1000^2 m^2) = 2.345 N/m^2$ The typical pressure from solar wind at 1 AU is $6\10^{-9} N/m^2$, our required average pressure is $2.345 N/m^2$ , almost 9 full orders of magnitude higher. Keep in mind that the average solar wind pressure will be around $3.75\10^{-12} N/m^2$ at 40AU, thanks on the inverse square law, and our situation really looks bleak. To achieve our necessary acceleration will require a surface area of: $Force = Pressure\Area = Mass\Acc $ $Area = Mass\Acc / Pressure = 5,000,000kg \* 18.8m/s^2 / 6\10^{-9} N/m^2$ $Area = 1.56 \ 10^{16} m^2 = 1.56\*10^{10} km^2 $ That's a square sail with side length 125,166 km, which would require MUCH more mass than we are accounting for. Using 0.005 c we still need a sail that is a disk with a radius of 7054km, which is a bit bigger than the Earth's radius. And remember thats assuming we have a constant flux equal to that at 1 AU. In reality its much worse. Solar wind is simply not dense enough to slow you down appreciably, especially when you factor that the sun's gravity will be accelerating you towards it, probably with more force than our sail can generate. To slow down your craft, you will have to eject mass. Forcefully jettisoning your sail will probably net you more deltaV than trying to use it. If you have a magnetic acceleration cannon of any type, start scrapping unnecessary (non-vital) modules of your ship and firing them at max power straight ahead. Venting atmosphere will help too. Good luck. [Answer] Solar sail - unlikely. [Here](https://www.quora.com/Could-it-be-possible-to-ride-cosmic-winds-as-a-means-of-space-travel) is an example of ship's project that would be able to reach 0.00264c(20 times less than you need). To increase delta-v 20 times you would need rather big technology leap. Magnetic sail is better because it is mostly made from magnetic field, that is pretty much weightless. There are [some projects](https://arxiv.org/pdf/1603.03015.pdf) that are able to decelerate from 5% c using existing technology. ]
[Question] [ ## Is it realistic for a world where dissident individuals with no public profile have a means to obtain protection from a hostile regime? ### Topic Clarification Obviously this is for the community to decide, but let me present my best case as to why this question belongs here. I will regurgitate a few things from the comments, as the makings of an important discussion are there. With regards to the relevance of this question in the context of world building, consider the following as I explain why world building for this question: My world is merely inspired by real political events rather than strictly based in reality. I see other SE communities as too rigid, and lacking the creative elements I need to weigh as I continue to build my world's political and societal landscapes. In the post I do mention "individual" frequently, but I mean this in the general sense, in other words we're not discussing the actions of a specific character (which of course would be off-topic): It is not about the actions of any one individual, but rather the feasibility for any such person inhabiting the world. Thereby, the question is appropriate as per the reality-check tag as it is commonly understood. --- ### Premise by public profile I mean: having a degree of fame, well-connected. Suffice to say people will notice fast if you go "missing" In this world there is a malign regime that dispatches a secret police force that can crack down on any dissident groups and make individuals "disappear." Often this amounts to the individuals being kidnapped and detained for life. For the rare cases where the individual has a mighty public profile, the regime assumes that making such influential people disappear would make a "martyr" out of them leading to undue reinforcing of dissident sentiment. Instead, the regime prefers to keep the dissidents with public profiles around but at the cultural and economic fringes of society. They are made out to be raving conspiracy theorists, and there are no financial incentives for others to associate with them. Let's take a brief cut-scene to the real world to understand how a regime's economic disenfranchisement might look like... As [Yevgenia Albats](https://en.wikipedia.org/wiki/Yevgenia_Albats) of Russia based New Times Magazine recently said in an interview when asked how she operates: > > "They allow some opposition voices to exist. But I had to close the > paper version of my magazine because people were afraid and are still > afraid to give us ads. We're running on a very small budget, only > digital, and most likely we will go out of business in the months to > come." > > > Moving along, sometimes the fictional regime in my world even targets individuals without a firm basis for dissident activity. It is uncertain whether the regime chooses to do this out of sheer megalomania or if it is premeditated at the secret police debriefings. Regardless, those individuals who find themselves in the crosshairs of the regime and lack the public profile of the more illustrious dissidents seem to have very limited ways to protect themselves from being detained -- at least in theory... * Media: - All media channels are state controlled and unsympathetic to the plight of the targeted individual * Knowing important people (connections): it is conceivable that an individual with little to nothing in terms of a public profile will still know one or two influential people, but unless that person is a close friend or relative, it's hard to say if he/she would step in merely for an acquaintance. Also, even under the influential close friend/relative scenario, there is also the risk of inaction due to fear of the regime. All things considered, having "connections" seems to be more of a roll of the dice than a plausible way to avoid capture. * Asylum/Smuggling: - While this state does not have closed borders, it does however collect very granular data about who is going in and out of the country. Once the individual is targeted, he/she will be blacklisted by all outbound modes of transportation. Due to geography and finite resources, it is extremely impractical for the malign regime to monitor every rugged and far-flung corner of the territory. An escape via smuggling is plausible, but an Interpol-like entity would carry out man-hunts even abroad. As difficult as life on the run would be, it would be better than life-long detainment and possible torture. Question: Is there a way for a dissident with little to no public profile to speak of (a nobody, if you will) and modest resources to avoid being detained if targeted by a malign regime who intends to make him/her "disappear" without ironically disappearing oneself? Further clarifications * financial resources: poor to middle class * lead time of detainment: approximately 1 week. Assume that the individual knows he/she is targeted. (clearly a best-case scenario) * reason for targeting: political dissidence, for this individual it's not a case of mistaken identity or random detainment. He/she knows what he/she said or did to upset the regime. * reason for not wanting to flee/smuggle out of the country: Be it stupidity or passion, although our dissident individual is a "nobody" with few followers or connections, but he/she is still resolute about the principle of playing a part with boots on the ground. Leaving the country will forsake the cause in ideological terms. * resources spent by regime on capture of dissident: moderate. Imagine a small, but skilled team working to detain the individual. * setting: present to very near future * protagonist: none, everything is narrated in matter-of-fact fashion, the tone is neutral [Answer] As a counter argument, the regime can do this with little or no effort, using something like China's "[Social Credit](https://infogalactic.com/info/Social_Credit_System)" scheme. Much as you can earn reputation or credit on sites like Worldbuilding Stack Exchange, or "Likes" on Facebook, you get "Social Credit" scores by using social media and other tools approved by the Chinese government in ways that the Chinese government approves of. This might not seem to be much of a problem, since no one has to join Worldbuilding Stack Exchange or Facebook in the West, but under a totalitarian government, everyone might be forced to have an account (indeed, providing a social media account to children when they first go to school and instructing them on the "proper" way to use it would overcome the avoidance problem). As an example, the Canadian government is pushing the "[Carrot App](https://fee.org/articles/creepy-canadian-app-gives-citizens-points-for-making-government-approved-choices/)" for citizens to put on their Smart Phones (evidently they were unaware of the irony of the name: when is the corresponding "Stick App" coming out?). The app invites users to "engag[e]in government-approved messages" (pretty Orwellian wording right there). As well: > > In order to use the app, users are giving Carrot Insights and the federal government permission to “access and collect information from your mobile device, including but not limited to, geo-location data, accelerometer/gyroscope data, your mobile device’s camera, microphone, contacts, calendar and Bluetooth connectivity in order to operate additional functionalities of the Services.” > > > A logical progression would be for the government to demand the app be pre installed on every smartphone and device sold in Canada, and then after a suitable time, begin modifying access to government programs based on your "participation" and use of the app. No logons or "engaging in government-approved messages"? Well I guess you don't need Unemployment Insurance payments or government healthcare either..... So your character (or any dissidents, for that matter) would have to totally disconnect from the grid. No bank accounts or means of paying or receiving payments outside of cash. No rental agreements or mortgages for housing. No shopping in supermarkets, no utilities, no telephone or email....nothing. Even being in public spaces would probably be a bad thing, nations like China and the UK have massive numbers of CCTV cameras, and China also has aggressively implemented facial recognition software on their surveillance network as well. The alternative would be systematic identity theft by the character (quite possibly involving stealing smartphones as well) in order to temporarily evade detection. This would need to be done daily as a minimum, since your activities would raise flags the farther they deviated from existing records of the person you are imitating. Movement patterns, purchases and so on would have to closely track the stolen identity, otherwise an alert would be generated and this could possibly send the regular police or security services to come and investigate. The last defence would to switch from passive to active opposition. While deleting your "social credit" account might be impossible, it may be possible to hack the account or add apps (which the regime would see as malware). [Ad Nauseam](https://adnauseam.io) is a currently existing app which you can apply to your browser. It automatically clicks every ad on any site you visit, which immediately turns data collection by Google Adware into hash, and degrades the value of your profile to Google (when they try to sell your data to advertisers, your preferences are buried in a welter of "noise"). Of course, unless you are an industrial strength coder and are adding something like [STUXNET](https://infogalactic.com/info/Stuxnet) to your smartphone, this too will quickly be detected and alert the security services. An "Ad Nauseam" worm that rapidly infects large areas might mask your tracks, but once again, requires some pretty heavy duty skills. So living under oppressive regimes which actively wish to harm you becomes very dangerous and time consuming. You essentially need to become a totally "grey man" and blend into the environment so you don't stand out whatsoever, or completely extract yourself. If the government randomly attacks citizens to keep the population cowed, even that isn't a true defense mechanism. Soviet era dissidents who fought the regime used paper based [Samizdat](https://infogalactic.com/info/Samizdat) demonstrate that it is possible, but a very slow and dangerous process. [Answer] Please Look at my other answer, it is of much higher quality This one is left up for reference, the other one is extremely different. It really depends on the resources of the regime and how involved they need to be in order to not just "disappear" to avoid the regime. In the best case scenario, you could hide forever if the regime did not put a whole lot of effort into tracking this person and you just stuck around the edges of town, stealing food and clothes. Or even go into the wilderness, surviving off the land, but I believe this is going against the spirit of the question. But if the regime really wants this person gone and has some basic surveillance, and the protagonist is not willing to go into the wilderness, then I would be suprised if our plucky protagonist survives the day. All you would need are cameras and people which can track the protagonist through crowds, and perhaps two dozen men to make sure they corner and aprehend them. If the cameras see them go into the sewer, assuming it is possible for civilians to access, more men are required, and could just guard the possible exits of the sewers. Although this could our time about a week, it is not suggested, as the protagonist would either give up and get caught, or they would drink the water down there, and die from a fun disease. Obviously, I am no expert in this case, but I think a decently competent regime would take a one day to roughly a week, depending on how clever and strong-willed the protagonist. [Answer] ## Hide in Someone's Home As with Anne Frank in the attic, your targeted nobody could stay with a family member, a friend, or a friend-of-a-friend. The more remotely connected, the better, because the regime team sent to find him (or her) will think to check family, friends, and associates. The best case might be someone that a friend-of-a-friend knows is sympathetic to the problem, and has set aside a hidden room or basement for people to hide in, even in the event of a search. This takes care of food, water, and exercise (when the regime's agents don't appear to be around, life might be almost normal). ## An Abandoned, Special Place This could be in the upper space of a mall or grocery store, a concert hall (like the Phantom of the Opera), a church, the roof of a hotel. Or it could be a secret garden forgotten between the walls of urban sprawl, or a part of sealed off or re-routed part of the underground (sewer, tunnel, or rail). What is essential is access to food, water, and other basic essentials. These might be foraged in short trips out. Or the hider could be bolder, in plain sight when the authorities appear not to be around. ## A Church or Embassy Alternatively, the target of the bad regime might petition for and be granted sanctuary in a church or foreign embassy. Especially if the target is a nobody, they might live a somewhat normal life, mindful of the occasional attempt to take him into custody if he leaves the property or is caught alone. This would be a fragile safety, because all concerned understand that the regime could, with enough provocation, throw the ideas of sanctuary aside, and come in force to make an arrest. [Answer] Given some clarification of the question, I believe I can give a better number. @RonJohn brought up a good point, as this answer is very different from my last one, and took his advice moving the answer into a new answer slot. As a side note, the regime and the task force is used throughout this question interchangeably. Initial Concerns First, the dissident needs to worry about how to obtain things for his survival. There are three things the dissident needs in order to survive: 1. Food/Water. Without these, the dissident will die rather quickly. Assuming the regime can track all transactions (such as China's social credit), buying them are out of the question. Our dissident would have to steal all of the food and water he/she needs, and be able to leave from the area very quickly. 2. Information. The dissident needs to know where to go if the regime catches up to him, where to get more food and water, where any sympathetics may be, and most importantly, the location of other towns. 3. Medicine. The dissident is going to get sick eventually, and if the dissident does not know or have medicine, then the dissident is in trouble. The dissident cannot go to a hospital, as the regime would know who and where is is almost instantaneously. Any illness which would reduce the ability to move quickly would be a huge pain, and for the sake of the argument, once the dissident gets sick, he gets caught. Assuming the regime has some basic cameras set up just about everywhere and they knew where the dissident was at one point, I imagine they could track him just about everywhere within an urban area. If we assume the dissident cannot leave urban area (towns and villages count as urban for the sake of the argument) and hide out in the wilderness of the country, there are two options. Hiding In the City This is probably the worse of the two, as within the city, I doubt on could be mobile enough to be able to avoid the cameras for long. One of the answers mentioned hiding out with friends or friends of friends, but the task force could find him easily, even if he hid with complete strangers. You could run into the sewer and hide there, but the task force then only needs to guard any possible exits if they want dissidents alive, or start throwing gasses in the sewer if they don't. That is assuming, of course, the sewers do not have cameras in the sewer as well, and civilians can go into the sewer. Food is going to be an issue, because of the prevalent cameras. When a robbery would be reported, the regime would have another point in time to track the dissident from, and it would all be over quickly after that. Water may be less of an issue, as you could drink from the sewers, but is obviously not recommended. The dissident will most likely not survive long enough for medicine and information to be an issue. The dissident could probably survive the month if they were really lucky and kept moving around the city, but a week is my estimate if the task force has enough men to watch the cameras and capture the dissident. Bouncing from Town to Town I believe someone could stay away from the task force much easier if they moved from town to town, never staying for more than a week at one place, moving as randomly as possible. This way, the task force will have to broaden the search to all surrounding urban areas, in hopes of catching a glimpse of the dissident. Food and water would be much less of an issue, as getting away would be much easier. In a town, it could be small enough you could steal all of the food and water you could need for a week, and get out of town and on the road to the next one. Information could be obtained by talking to innkeepers and storeowners, assuming the dissident's face is not in circulation, and if not, it could be asked from smaller children where some nearby towns are. Smaller children are less likely to recognize the dissident if his/her face is in circulation, and he/she can be dismissive if they do recognize him/her. Medicine is still going to be an issue, as I doubt the dissident could steal some food and medicine in the same town, and food and water is going to be tight as is. Even assuming the dissident gets some medicine, there is little guarantee the dissident will know how to use it. Realistically, he could survive a year or two until he gets sick. But theoretically, the dissident could do this for years or decades, until the dissident gets too old to keep moving at the same pace, which is unlikely, given the dissident will certainly not be living in the best of conditions. Final Note Obviously, I am no expert in this subject, some numbers are just pulled from my intuition, but this may give you a place to start. ]
[Question] [ Tl;DR: I'm doing an urban fantasy story with magic/superpowers, and I'm trying to decide a way to keep technology out of my fight scenes without doing away with technology entirely if at all possible. I have one method that I feel works but needlessly overcomplicates worldbuilding, and a fallback that's not ideal and defeats the point of some of the story's themes but is much easier to worldbuild with and could be fun in its own way. I’m wondering if anyone has a way to salvage one of them or has a third to offer. As a newcomer here, I'd like to apologize and thank you in advance for your patience with the incoming wall of text. I have this recurring and incredibly frustrating problem with my story with regards of handling technology in my urban fantasy, and I could really use some advice. So I'm writing a story about a world where an unknown entity starts giving the human race superpowers. Basically, in my setting, which is the modern day with a few adjustments, shortly after the story begins, everyone over the age of 13 has a brand on their arm that can hold four (later six) runes, and every week a new rune is added to the brand, representing a new superpower (it's the same rune for everyone per week). When the brand is full, whatever rune is in the last slot (they can be moved around with your mind) is replaced when the next week's rune is added. In addition to this, there are four more powers that are free and impossible to remove. The first two, which are given to everyone who was old enough to have a brand when all this started, are a healing factor (which doubles as an immunity to disease and aging) and a power that basically puts everyone, man or woman, at about Captain America's level physically, give or take in a few areas. There are two more, and unlike the first two you don't have to have had a brand when they were initially given out; from that point on everyone gets those powers when they get their brand. I'll get to what these next two powers are in a second. The story initially goes for pseudo-Harry Potter-esque supernatural slice of life plus mystery format for the six months worth of powers in the story, until it becomes obvious that there are certain powers that society as we know it can't survive everyone having, and unfortunately, everyone now has them. On to the point: technology and this story have a complicated relationship: I want to make it impossible to use in combat so that I don't have to make the powers god-level ridiculous to keep people from still favoring guns and tanks and such in a fight or war (also I think swords and bows are a lot more fun than guns), but I also want there to still be instant worldwide communication so that I can justify everyone having the same name for each power, and I love the idea of modern methods being used to make old-fashioned weapons. The idea I initially came up with to compromise on this point was having those later-issued permanent powers be a sort of anti-technology power that lets people blast an area the diameter of a two-lane street with an energy that renders electricity, combustion and chemical reactions impossible for an hour (living organisms are immune to this), with the second power being a force field that blocks all small projectiles, rendering guns useless and requiring ranged attacks to come from powers or larger projectiles like arrows. At first this sounded perfect, a system where for the most part technology works, but only when everyone who can see it wants it to, and a perfect catalyst for making shit hit the fan at the climax of the first book of this story and sending the world into complete chaos (along with a set of powers that facilitate mass prison breakouts). And with a single alt-history invention I could change the way the internet and phones work to make sure they'd be feasible to keep running too. The problem is that the worldbuilding implications are utterly mind-bending, as figuring out what aspects of modern life would and wouldn't be possible would hinge entirely on a thorough understanding of modern infrastructure, sociology, and also one's optimism about the goodness or lack thereof of the human race, and I don't know if I'd ever be able to truly comprehend what would and wouldn't be possible in a world where anyone can at any time make anything they can see not work. It's fascinating to me, but also pretty complicated and terrifyingly easy to get wrong. And so an alternative idea I had been throwing around was to send the world into full "power-punk" mode after the initial false sense of security of the first six months, and basically have the unknown entity do some sort of Dies The Fire or Revolution-esque change in the laws of physics that render most technology useless, forcing people to use their various powers instead to compensate. While this would make nearly all technology more complicated than fire off limits, I'd be able to create any power I want to replace the more important stuff, as long as I was comfortable limiting the number of hands it could be in since there's a limit to how many powers you can have. While I'd miss the opportunity to see how various powers would interact with our modern world, and I'd have to break the rule I want to follow about everything supernatural coming from these powers and nothing else (to keep with the theme of "Everyone getting superpowers wouldn't exactly be all sunshine and rainbows"), I wouldn't need to study every conceivable facet of human behavior and modern infrastructure and still probably get half of what I say wrong. Does anyone have any advice in this area? Am I overestimating the difficulty of working out how a world like Idea #1 would work, or am I right in thinking I'm biting off way more than someone can reasonably expect to chew and I'd be better off keeping things simpler and easier to understand and going with Idea #2? And can anyone who recommends going with Idea #1 give me any advice about any less obvious implications I'd need to think about? [Answer] In the Dresden files, technology fails in the presence of magic. Guns jam, computers short out. The longer the technology is exposed the faster it dies and the more complex the faster it dies. The main character, Harry Dresden, drives an old VW Beetle that dies periodically and a Chief's special revolver which may or may not work. Bad guys with machine guns jam up as soon as magic starts flying It's explained as using magic affect probability as opposed to stopping reactions [Answer] I seriously disagree that swords have any inherent coolness factor to them (which is why I can't take Star Wars seriously), but it's your story and you're the god of it. Actually, you're underestimating the complications from Idea #1. If you create a field that suppresses electrical activity, people's neurons stop working, and everyone dies. If you suppress combustion, cells cannot breathe, and everyone dies. If chemical reactions are impossible for one hour, all metabolic functions stop, and everyone dies. You can't have such a drastic effect apply only to objects and not to people: living organisms are subject to physical laws too. So you want not only guns, but even tanks to be unusable against a superpowered character. How about ordinary dynamite? How about tasers? How about napalm? How about poison gas? How about nuclear bombs? You need to set a limit for how resistant your magic is, because you can bet governments will attempt to nuke anything that resists air bombardment. Before I can propose a solution, I'll need more information. Maybe you could describe in detail what superpowers you're giving your characters? [Answer] What you need is a means of keeping modern technology "out" of the scenario for the period of time the story needs. This is rather difficult, since you are essentially creating mobile plot armour for the heroes, and could run into situational issues (for example, someone not expecting a fight does not have the "negate technology spell" activated and gets shot in an ambush). As well, the refinements have to be almost ridiculously specific; only some chemical reactions or electronic and electric fields can be cancelled out, otherwise everyone dies. It would be simpler to make people have powers which simply negate the effects of modern weapons, so I pull out the M-4 and put a magazine into you, but the bullets are shrugged off or magically deflected.... One final objection is how do you define "modern weaponry"? If I shoot at you with an [arquebus](https://infogalactic.com/info/Arquebus) does that count? What if I use a [Byzantine flamethrower](https://infogalactic.com/info/Greek_fire#Projectors)? What happens when I try to run you over with a car? If my [Winchester Model 1897](https://infogalactic.com/info/Winchester_Model_1897#Military_use) is fitted with a 22" sword bayonet, can I use it as a spear? For that matter, will a [Katana](https://infogalactic.com/info/Katana) made with modern steel using modern forging methods work, or do I have to smelt poor quality iron ore and hand forge it using traditional smithing techniques? To get the effects you want, I would suggest one of the spells is a form af magical "[Faraday cage](https://infogalactic.com/info/Faraday_cage)" which blocks "modernity" (however defined), which the person can cast over themselves and a small spherical area around them (perhaps an arms reach). That way bullets and so on are deflected, and only hand to hand combat would be possible (where bubbles overlap). Characters can team up to "blow" larger bubbles or link multiple bubbles together for whatever effects that generates. [Answer] Taking inspiration from the The Dark Eye roleplaying system: Magic and iron don't mix. Prolonged exposure to iron weakens the magic ability of the exposed person. The more refined the iron, the stronger the effect, so a chunk of iron ore weakens you slightly, a modern gun with it's high durability iron drains your power. You don't have to physically touch the iron for it to affect you, you just have to be close to it, so using gloves won't prevent it from affecting you. No magic, no superpowers. The physical strength from magic disappears and the healing factor is gone, so it's very undesirable for it to happen. You can still use swords, but they have to be made from bronze or other non-iron materials. They'll be weaker, though if I remember correctly more prone to bending than breaking. Technology won't be gone at all, computers don't have a lot of iron, apart from maybe the casing. Cars are a bigger problem, but it might be possible to handwave it away by adding a bronze mesh around the motor to keep the effect of iron contained and building the rest out of aluminium alloys or people just accept the magic draining cars for the advantage of moving around faster. [Answer] Why not give your super power system a long enough time period and special powers so that technology based weapons are phased out, being inferior and to and less accessible to the super powers. For example, one of the powers people might get is a shield that can block all projectiles travelling above a certain speed. Another power could have the same effect as a pistol, shooting bullets or air or just force at a person. Overtime, you allow some extremely powerful abilities to come out that over power technology, which leads to a shift in ideology that the powers are better than technology. This way, the people who are likely to fight with each other might try and keep these extreme powers, while those who are living normally will cycle them out for something more useful to their lives. Of course technology will still be there, but you can make it appear that getting access to something like a gun or tank becomes much more harder and less profitable with the rise of powers and more technology related to maximizing the use of the powers. Other than that, you can try go with the Harry potter method, but that falls apart the moment you look into it. Basically as mentioned before, technology simply does't work around magic/powers. But in the end Mechanical systems are still going to function perfectly fine and so should chemical reactions, so a Gun will still work and anything far enough can still murder you. Finally depending on your setting you can choose to completely ignore the use of technology. If your hero is in school or a city, it can be very unlikely that anyone they encounter will have a gun because of the prevalence of magic. You don't have to explain why there is no technology, if none of your villains use it, or you quickly over shadow it with how much more powerful magic can be and how much more useful it is. e.g. there is an electronic lock, but some one might have saved the power to open locks or someone shoots you and you have a shield power. Extra thought from my world, you can have it so that magical powers can be imbued into items that a person is in contact with, but the magic wears off/fades away over time. This way, a person can imbue magical powers into their swords to say set it on fire, or into arrows to make them explode on impact. However this requires energy and doesn't last a long time, so it becomes harder with bullets and machines. You can also adjust it so that it depends on size and material e.g. wood stores magical power better than metal(for archers), but metal exhibits greater magic power then actively fed magical power(for swords). If you combine this idea with a natural power to stop all projectiles above a certain speed (unless imbued with magic) you can negate almost all modern weapons. Note: it doesn't mean you cant use modern weapons, just that the time and cost investment has to happen at a more personal level aka a person has to imbue each and every single bullet they want to use with magic power and shoot them relatively quickly. Making it a unlikely choice to use as a weapon. [Answer] Would just giving everyone a 'anti-combustion and modern conventional weapon' work? Ie, it's one of the temporary powers, but enough people decided to keep it that it renders these things too unreliable to use? I think, is this case, it would be a matter of how specific you'd want the powers to be, and how much you want to squash down these types of weapons. In this case, people would still be able to use the modern stuff, but there would be enough circumstances where it wouldn't work for them not to want to- unless they knew for sure that noone in the group they were fighting against had decided to keep this power. This would allow you to make this a relatively recent introduction, to lessen the amount of alt-history you would have to write, or even just lessen how much it would diverge. [Answer] One of the early powers given out was essentially "anti-projectiles" - it included the ability to detect projectile weapons in your vicinity, to detect where they are pointed/aimed, and the ability to dodge or deflect projectiles. For that 1 week, guns became largely useless, and unlicensed firearms were seized in mass-raids by cops who knew exactly where they were being hidden. Since people can decide which power they want to "swap out" each week, every police force on the planet has someone who still has this power. Every Military force contains people who still have this power. Every security company at least claims to have someone with this power. This has forced both the armed forces and the criminal element to move away from guns as their weapons of choice - even if your target is too young to have this power, you might walk within range of a cop who can detect your weapon. Of course, guns are still the weapon of choice for hunting, etc. (Tangentally: Do people 'just know' what their new weekly power does when they get it, or do they have to experiment? There are ways that could go horribly wrong, such as little Johnny out camping who accidentally triggers his new fire-based power and burns the forest down around him - perhaps there a small group of people holding onto an otherwise useless power that just tells them what next-week's power does, and what the rune looks like. They are the ones who name it, and prepare a press briefing on what it does - this also lets them "downplay" aspects they think shouldn't be widely known) ]
[Question] [ This is a submission for the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798]) While researching ghouls, I came across two varieties: The traditional ghoul: a grotesque humanoid commonly featured in fantasy settings that may or may not be undead [![enter image description here](https://i.stack.imgur.com/v93Im.png)](https://i.stack.imgur.com/v93Im.png) The Pickman ghoul: Featured in H.P. Lovecraft’s story, “Pickman’s Model”, these ghouls are described as having an almost canine appearance, walking on hind legs and having rubbery skin. Both share the common traits of being mainly nocturnal, and feeding on the dead (mostly what they can dig up from graveyards). Could either creatures evolve naturally, or maybe both?” [Answer] I'm gonna go with the traditional ghoul, since it seems more plausible. I've done a lot of speculation regarding humanoid fantasy creatures, coming up with explanations for the evolution of beasts such as the troll, elves, dwarves etc. So, in all of these postulations, the theory has always been that the creatures diverged from humans. So, since ghouls are also very humanoid, I presume that their evolution would branch from that of the hominids. Most depictions of ghouls show them as hairless, pale-skinned humanoids with sharp teeth. So what we need to figure out is: 1) Why did they lose their hair? 2) Why are they pale-skinned? and, 3) Why are their teeth sharp? Now we must look to the real natural world to help us figure this out. Let's start with number one, because... well, because it's number one. Humans naturally have hair, though it can be removed, so the ghoul would have had to had a reason to evolve hairlessness. To answer this question, we can look for a bald creature in nature that has evolved from furred ancestors. The first creature that comes into my mind is the naked mole-rat, Heterocephalus glaber. This is a naked mole-rat: [![enter image description here](https://i.stack.imgur.com/Ioiju.jpg)](https://i.stack.imgur.com/Ioiju.jpg) And this is a normal mole-rat, or blesmol: [![enter image description here](https://i.stack.imgur.com/Y8LSH.jpg)](https://i.stack.imgur.com/Y8LSH.jpg) So, as you can see, the naked mole-rat lost its hair for a reason. It lives underground in a hot climate - this eliminates the necessity to protect from cold or the sun. So, we can speculate that your ghouls have a subterranean habitat too. Now we've got the problem of pale skin. When I think of a pale-skinned cave-dwelling animal, the olm comes to mind. [![enter image description here](https://i.stack.imgur.com/Z41DF.jpg)](https://i.stack.imgur.com/Z41DF.jpg) It lacks a lot of the pigment riboflavin, and is thus pale in colour, even translucent in places. I haven't been able to cross-check it with any written online source, but I presume this is because of the darkness in caves. There is little light, and therefore no need for pigmentation. However, the olm has also gotten to the stage of evolution where it is blind. I cannot find any source to state that pale skin evolves sooner than blindness, or if one is dependent on the other, so I'm gonna have to use the information I know for sure and say that, possibly, white skin evolves alongside, or after blindnes. Basically, that means that your ghouls could be blind, perhaps even eyeless. But, I presume you are using these ghouls for a horror story, or scary element to a story, so that might be a great idea to make them even more terrifying. What's more, most depictions of traditional ghouls online show them with white eyes, which could be an intermediary stage between sight and eyeleness. This might also make sense, since humans evolved fairly recently, so ghouls would've evolved even more recently. You may be wondering why I'm going to so much trouble explaining why these ghouls have pale skin - don't (White) humans have pale skin anyway? Well, earlier I said that they would have to live in a climate around as hot as the naked mole rat's range (East Africa), which is a lot hotter, usually, than you could get in Europe, home of the Caucasians. Now, hairlessness; check, pale skin; check (plus blindness), now all we need is sharp teeth. It is a relatively well-known fact that herbivores have blunt teeth and carnivores have sharp ones. Here is a domestic cow tooth, compared to that of a lion: [![enter image description here](https://i.stack.imgur.com/Xf49G.jpg)](https://i.stack.imgur.com/Xf49G.jpg) [![enter image description here](https://i.stack.imgur.com/qPrSA.jpg)](https://i.stack.imgur.com/qPrSA.jpg) Ridged, blocky teeth are good for grinding plant fibre, while sharp teeth cut through flesh like no other shape. So, your ghouls are gonna have to be carnivores. So, unless a whole ecosystem of megafauna has evolved without sight in a cave system, which would be cool, but perhaps to "monumental" just to justify a creature in the plot, the ghouls will have to come out of the cave to eat meat. If you want to justify the hairlessness, they'll have to do it at night, somewhere either with a warm night temperature (Not sure if that exists), or just for brief periods of time. One carnivorous cave-dwelling creature that comes out of its cave at night is the bat. They are not blind, as rumours would have you believe, but have the same level of night-vision as us - which is pretty terrible as animal sight goes. Obviously, they navigate with echolocation, by sending out sound waves of sound that bounce back to them. But for that, you need massive, massive ears - which ghouls lack. [![enter image description here](https://i.stack.imgur.com/fBDBV.jpg)](https://i.stack.imgur.com/fBDBV.jpg) So I advise that your ghouls use a very good sense of smell instead. But, we still haven't figured out why their fully carnivorous. Unless there's some strange event in your ghoul's habitat that kills massive numbers of animals daily (Which only the most biodiverse of ecosystems would survive, considering the accumulative scale of the necropsy.), these ghouls can't survive on just carrion. They'll need to be hunters. Humans, as a species, are pretty terrible at hunting without tools, so ghouls would be faster and stronger than us. This whole predatory thing could add another chilling element to your story - the thought of a pale, eyeless human killing a deer is rather sickening. At last, we're done! Sorry for the gigantic answer, but I hope it's been fruitful. To summarise your ghouls, they are a species diverged from Negroid Homo sapiens sapiens, driven into subterranean life by predators, discrimination or other threats, and they have the following features: Pale skin Hairless Eyeless Sharp toothed Long-legged Muscular Well that's enough from me. Happy worldbuilding! [Answer] This one is pretty easy. Ghouls are degenerate humans. Degeneracy of humans (or other intelligent species) over the generations is a favorite theme in Lovecraft's fiction. The possibility that an individual human might be contaminated by blood relationship to these degenerates is also a favorite theme, whether the degenerate heritage be fish person, ape person or ghoul - Pickman as mentioned was part ghoul. Your ghouls are the degenerate descendants of a conquered race of humans, driven to shelter in ancient tunnels and labyrinths. They might not be physically much different from humans except behaviorally - I think now of Neil Gaimans ghouls in the excellent [Graveyard Book](https://en.wikipedia.org/wiki/The_Graveyard_Book). Their sole caloric source cannot be corpses but when you are living underground calories are scarce and waste not, want not. Plus it is a way for the ghouls to put a thumb in the eye of the surface dwellers who conquered their ancestors and drove them underground. ]
[Question] [ I'm writing a story about a group of humans (or humanoid people) that are living on a spaceship that's orbiting a planet with high gravity; the force is too much for direct human involvement. There are limited technologies available to deal with the natural terrain of the planet, as it is incredibly hilly and have a lot of thick vegetation, and so expeditions to the planet are limited to accessible areas using vehicles to conduct experiments and general research. So as a method to gain direct access to the natural land they take a native species and genetically modify it to be compatible to the human brain (removing extra limbs, altering it into a "bipedal" makeup, etc.). I call it a mech primarily because there is a space in the head where the "pilot" enters, is attached via needles in the spinal cord and advanced invasive EEG, and then put to sleep, limiting the functions to the mech instead of any conflicts between it and the pilot. I want a valid reason as to why they couldn't just create a mechanic "mech" suit? Them developing a pilotable GMO that requires invasive brain surgery seems really steep, as far as cost/benefit. I have some ideas; their resources are limited, they want to interact with the environment in a more natural way, or something about the environment is especially corrosive or detrimental to the metal they have access to. But it feels wishy washy. At least to me. (Also on a side note, could high gravity planets even create very large fauna/flora? Or is that unrealistic?) Any advice would be wonderful! I'm also very flexible as to what I have currently, and any sorta ideas or suggestions you have story wise would also be interesting. The more hard-sciencey the better [Answer] # The Power of the Human Brain In this setup, the human brain can handle anything you throw at it. We are already attempting to control [prosthetics with our minds](https://gizmodo.com/darpas-mind-controlled-arm-will-make-you-wish-you-were-1776130193). I don't see why the arm can't be [an extra arm or 4](https://en.wikipedia.org/wiki/Doctor_Octopus). On the assumption that the human brain can handle all sorts of "enhancements", here is why a biomech is preferred. # Extra Sensory Perception All of the senses from the the original organism are fed strait into the pilot's brain. If the biomech can see [Ultraviolet light](https://en.wikipedia.org/wiki/Bird_vision#Ultraviolet_sensitivity), the pilot can now see UV Light. If the biomech has some [non-human sense](https://en.wikipedia.org/wiki/Ampullae_of_Lorenzini), the pilot now has those same senses. Additionally, these are the sensors the evolution has chosen, not some spreadsheet on someone's cell phone. # Locomotion Locomotion is hard. But, evolution solved it a long time ago. For a pilot, simple walking is easy. The pilots only need serious training if the biomechs are going to need the fine motor control found in sports. Also, I see no reason why you have to modify your beast for bipedal walking. # Cost Biomechs are cheaper to build. Since the biomechs originate on that planet, you don't have to pay for the extra fuel needed to transfer the biomechs from the warehouse to the planet. Because the biomechs have the ability to self-repair, biomechs are cheaper to maintain. [Answer] Bans on Mechas Mechas and similar machines are banned by several international laws. Most governments don't want to see their colonies getting heavy weaponry. Most corporations want exclusive deals to supply the colonies with heavy machinery, so they don't want any local entities producing their own mechas. Disruption of local life These scientists want to cause the least possible disruption of local ecosystems so that they don't get wonky data, having a giant metallic robot stepping around, belching fumes, and leaving behind all kinds of detritus will certainly make the observation of undisturbed species almost impossible. A good example are the mating habits of Grasshopers, for a long time they believed it was normal pratice for the female to devour the male after mating, but it was recently discovered that the female will only devour the male if under stress. (Possible source of stress: A scientist looking at her while she is trying to mate) [Answer] > > a valid reason as to why they couldn't just create a mechanic "mech" suit? > > > Mech suits require metal, which is in short supply on a spaceship. Mine it, you say? But mining is a resource-intensive heavy industry: not something you'd do on a heavy-gravity planet unless the metal is really valuable. [Answer] Make all of their tech biological. Biology is a natural form of nanotech, if their normal way of doing things at this point of their civilization is to hijack genetic code to engineer everything - ships, computers, weapons, etc. (You should be able to program a cell to manufacture fiber optic cable - or plasma injectors, so you can just go nuts with this). If for whatever reason they need a giant mech that's specifically adapted to some planetary environment, then growing a purpose build organism from local fauna with a wetware interface would just be standard operating procedure. ]
[Question] [ I'll confess that I have a real issue with iron--it rusts quickly. In fact, the History Channel program Life After People constantly states that, left to its own devices, the iron that makes up a skyscraper's skeleton would have a standing lifespan of 100-150 years before rust weakens the skeleton into pieces. Long ago, I asked a question [regarding the construction of metal weapons without the use of iron at all.](https://worldbuilding.stackexchange.com/questions/84592/a-non-iron-elvish-steel/84669?noredirect=1#comment324718_84669) In the answers selection, many candidates have been suggested, and they are: 1. Titanium Alumnide 2. Nickel Superalloy 3. Nickel Alumnide 4. Stellite 5. Tungsten Carbide 6. Zirconium Carbide 7. An alloy of Titanium and Tungsten What makes this list relevant to the question is that steel or any other kind of alloy had been used to make weapons before their use in construction, so the principle would be identical. In an alternate, cyber-or-steam-punk New York, Chicago, Dallas or any of the United States' biggest cities, these listed metals and alloys had been considered for construction of mega-towers (a little like [this](https://steamcommunity.com/sharedfiles/filedetails/?id=868797945) or [this](https://wallhere.com/en/wallpaper/221588) or, if you want to go more historical, [the artworks of Hugh Ferriss](https://untappedcities.com/2011/11/16/the-new-york-city-that-never-was-a-visionary-dream-of-the-1916-zoning-resolution/).) Using the science involved, which of the listed metals would be strongest in regards to tension, compression and resistance to corrosion? Oh, and before anyone asks, this question stresses on quality, not quantity. [Answer] If rust is the problem, why not trade iron for stainless steel? A quick look at [coefficients of thermal expansion](https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html) suggests that you can get stainless steel with a similar coefficient to that of concrete, and because it's so similar to iron, you won't have to change your construction methods much, if at all. [Answer] Researchers at MIT have used graphene to develop a lightweight material that’s 10 times stronger than steel that could potentially be used to manufacture vehicles and devices, as well as in building construction. A team of researchers in MIT’s Department of Civil and Environmental Engineering (CEE) designed the 3D material—one of the most lightweight and strongest ever developed—by compressing and fusing flakes of graphene, a two-dimensional form of carbon. The result is a sponge-like configuration with a density of just 5% that is incredibly strong, they said. Graphene, in 2D form, is believed to be one of the strongest of known materials, but its strength in the 2D world has been difficult to translate in a 3D material. Graphene has exceptional strength, but because of its extraordinary thinness, it is not very useful for making 3D bulk materials that could be used in vehicles, buildings, or devices without first translating graphene into three-dimensional structures. The geometrical configuration of the is the dominant factor in their characteristics and the success in using graphene to design them. Researchers developed the material by compressing small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure with shapes that resembled some corals and microscopic creatures called diatoms ~credit: "designnews.com" and "MIT.com/CEE" respectively [Answer] Why metals at all? Concrete and [composite rebar](https://www.compositesworld.com/articles/a-hidden-revolution-frp-rebar-gains-strength) (carbon fiber reinforced plastic, glass FRP, aramid FRP) construction is now used in structures such as bridges precisely because they do not rust, and are light. Such technology could be applied to [concrete skyscrapers](http://www.constructionweekonline.com/article-9184-top-10-worlds-tallest-concrete-buildings/). The same technology applies to [truss structures](https://www.compositesworld.com/articles/composite-trusses-for-large-structures). There is a clear path today towards replacing structural steel with composites. ]
[Question] [ First i'll introduce the settings, it's the same one as for my previous question (about currency). It's happening in post-apocalyptic SE Europe (Balkans specifically), about 60-80 years from now. Strange genetic disease wiped out large portion of humanity in a matter of a few years. The rest of humanity killed and pillaged each other until our numbers were indeed few. The surviving humans have a genetic disorder which makes pregnancy harder. Nature is, for an unknown reason to people, thriving, mutating, being more hostile to people. Wild plants are growing slightly faster, predators are bigger, stronger, smarter and more dangerous. Beside that there are the "wild ones", feral humans that live like animals. All this has made trade and traveling quite hard, but not impossible. Cities are overgrown, forests are bigger. People are living in smaller independent settlements (100-400 people), scattered, fortified. Bandits and roamers are common. Settlements are somewhat self sustaining, but still need to trade between each other, because resources they have access to are different. There is one specific settlement in the area, based around the old University, which harbors and preserves "old" technology and knowledge, and uses that knowledge as a commodity, fixing and making technological stuff for other settlements in exchange for food, protection, and so on.. There is no unified government or force, and all attempts do do such have failed. Technology is somewhat preserved, but only partially. For example, people know what solar panels are, or that somehow electricity can be produced from a windmill, but only a very few people actually know how it works and the science behind it. For the QUESTION - How would those people produce ammo for firearms? Ive done the research, and in this setting, without working and organized industry, chemistry behind production would be a problem. After that much years passed, old reserves of ammo are almost depleted, and whats not depleted is getting bad, even the stuff safely stored. People need to make new ammunition. Casings are not that much of a problem, nor is the propellant, all that can be made by mentioned limited technology, or even DIY... The biggest problem is the primer. Production of that (on any scale, home or industry), requires advanced chemistry, materials and so on, and for these people simply not available. If i am wrong, and this is way simpler then it looks to me, please do say. For examples sake, lets say that someone in the University settlement has above the average knowledge of chemistry (average bachelor student level, but far from Walter White level), so he knows what goes inside it from theoretical angle. And the surrounding is an overgrown hostile ruins of a city that used to have half a million people, so various things are possible to be scavenged. If it comes that this is not possible on any level, or really really hard, I was thinking that what would happen is to technologically downgrade firearms, onto the technology level in the past that is able to function in this settings, and make production possible? Perhaps pre 1st World War rifles or something like it? Any insight or ideas are helpful! Cheers [Answer] My primer of choice would be [Mercury Fulminate](https://en.wikipedia.org/wiki/Mercury(II)_fulminate), which was used for the first [Percussion Caps](https://en.wikipedia.org/wiki/Percussion_cap). You wouldn't necessarily have to have them be an external primer - Including the percussion cap in the base of a cartridge is effectively the same method as a modern centerfire (And if I have my history right, there were guns around the 1850s that were exactly that). These would have to be manufactured by your University - From what I've been able to gather, it's a process that involves some fun chemicals. While centerfire rounds would be possible, I expect they would be less common. A percussion cap has some nice advantages in a mixed-tech world: * They can be made by one location (Such as your University or an associated place) and traded out without having to make or sell the other parts of the cartridge. Powder, bullets, and casings can be made far more easily than caps, so someone would just have to be able to make caps, and the consumers can do everything else * They can be included as part of a centerfire round as mentioned above, or as an external primer. * Weapons designed to use percussion caps as an external primer are very similar to flintlock weapons. Flintlocks are good for those that want to be truly independent, and the similarities in weapons would allow a gunsmith to make whatever the customer needed. And if the customer wanted to change the weapon from one to the other, it's not difficult. * Percussion caps, like many primers, can be used with a variety of powders. "Black" powder, if I have my information correct, can be made easier than "Smokeless" powder. It does foul the guns quicker, but a slower-firing weapon such as a converted flintlock won't have that issue. If you want an automatic weapon, you'd still be able to use the percussion caps as part of the casing, with more advanced powder being made by the locations that have the resources to dedicate to it. * Percussion caps can work with many styles of weapons, from fairly advanced weapons that use centerfire caps, to revolvers that place the caps behind the weapon's casing, to breechloading weapons, to muzzleloaders that don't even use casings. So now I've gone on about percussion caps, but that wasn't exactly what you were asking. Making Mercury Fulminate requires three things: Mercury, Nitric Acid, and Ethanol. How do we get them? Well, Mercury can be mined, and has been used since very, very early times. One of the primary sources of Mercury for a very long time was [Idrija](https://en.wikipedia.org/wiki/Mercury_(element)#History), which sits right with your Balkans location. OK, so now we have Mercury. That was easy. What's next? Nitric Acid. How do we get it? The simplest method (Dating to the late 1700s) is the [Birkeland-Eyde Process](https://en.wikipedia.org/wiki/Birkeland%E2%80%93Eyde_process) - This does require electricity, and a bunch of it, but you've already mentioned that electricity exists. To make Mercury fulminate, you dissolve Mercury in Nitric Acid, and then add.. Ethanol. Ethanol can be made by [yeast](https://en.wikipedia.org/wiki/Ethanol#Natural_occurrence). So we have everything we need to make Mercury Fulminate, and can put them in percussion caps. How those percussion caps are used depends a lot on who is using them and how well they can maintain their technology. More remote locations might use flintlocks (Although they might have issues with rain, where percussion caps might have an easier time). All of this is capable of being done without significant amounts of technology, although it's significantly easier the more tech you have available. [Answer] Ditch the primer completely: The world you describe will be one where getting any sort of resource will be a lot more dangerous then our own & on top of it you have a very limited number of people to put in the required work to get said resources, treating all the man hours needed to gather said resources just to have them thrown away whenever a bullet is fired is wasteful, that may not be important in our modern "single use then toss it" world but in a post apocalyptic one where stepping outside your secure compound\town means risking death it would be wise to avoid wasting anything. To fire a gun all you really need is a bullet & a source of high pressure to move it along the barrel, everything more is extra and isn't mandatory: Casing - musketeers would pack gunpowder & the musket ball separately - you could also use a paper casing like they did back in the days to avoid wasting that harder to make brass. Primer - the real answer to your question, don't have one, even if you are using a Firearm all you need is a spark to set the gunpowder\smokeless powder off, that can be a matchlock, electric spark or even a lit slow burning fuse, the main point is that whatever you chose is a part of the gun rather then an expendable bullet that's used once then discarded. Gun powder\smokeless powder - You don't even really need to use this, compressed air was used in the past to hunting big game & for war, for long term survival not requiring to keep gathering the materials to make gunpowder might allow a smallish group of survivors to use their limited amount of manpower better The self contained cartridge makes life simpler if you have the resources to spend for it as it allows for a faster rate of fire but judging from your OP it seems nature is your main enemy, and you don't need suppressive fire when fighting a bear, even if there are some groups in your world that have the ability to create modern ammo they would be better off spending there time & resources elsewhere & stick to older designs in the firearm department. TL;DR - use air rifles or old style rifles/guns that don't require a unique primer & save your resources. [Answer] Better Living Through Electricity I had occasion to be considering this in a non-standard Traveller campaign I was running a year or so ago. If basic electrical equipment and knowledge are available then something along the lines of a battery powered glow plug could be used to ignite your propellant. (I am thinking about the type of glow plugs used in model vehicles, not the full-sized types used in diesel engines.) Imagine a cartridge with a thin paper base (the cylinder wall of the cartridge could be either cardboard or metal). When fired, the hammer would drive the ignition point of the glow plug through the paper base and into the propellant (instead of driving a firing pin into the primer). I have not personally experimented with whether this would work or calculated the power (battery) requirements if it would. However, this would be an alternative for any communities that have access to basic electricity and the plentiful supply of salvaged glow plugs and lack the expertise to undertake the dangerous business of messing around with manufacturing primary explosives. This could be an alternative used in one or more communities that are not trading with the manufacturers of mercury fulminate primers as described in Andon's excellent answer. [Answer] Considering how limited these peoples' access to immobile reasources, I'm gonna assume that you want a weapon that does a lot with very little. I suggest a weapon that reuses its ammunition. Take any projectile weapon, and modify it so that you can use the ammo again. An arrow that is easily lost in the bush? Nah, attaching a small rope or string to that arrow to make it much easily to retrieve? Why not. A bullet that deforms afterhitting the target, so you can't use it again? Nah, launcher a (heavier) stone at lower speeds so that it still does damage AND you can retrieve it after the battle? Nice. Also, since(I'm assuming) things like chemical propellants, high quality metals, and anything else that requires lots of infastructure is not very availible, looks to weapons humans throughout history have used where infastructure was not something you could rely on. ]
[Question] [ Suppose you had two intelligent species that came together and built a society or whatever. For the sake of example, we'll call them species A and species B. Species A evolved to see some subset of the visible light spectrum (or all of it), and can distinguish various "colors" in that range due to having multiple types of cones with varying sensitivities to radiation in their visible range. Species B evolved a different range of visible radiation, but can also discern "color" within that range using similar biological features. Maybe they see into ultraviolet or infrared radiation. They might have some overlap with species A's spectral range for vision, but perhaps the two are entirely disjoint- though not terribly far apart. What sorts of difficulties would arise from these two species trying to cooperate and communicate? [Answer] Any difficulties will be of the minor irritant variety. Black will still be black and white will still be white (well, sort of, for white). White may appear to be biased toward other colors depending on how much and what part of the spectrum it contains but it should be noticeable as an attempt at white. There would be colors that one might be able to perceive and the other not but that won't be a problem once it is known unless one party is being purposely obscure. I suspect that this will be the biggest non issue the different races have. Visual communication will involve using color pallets that both can perceive or color shifts in transmission. Lets say we encounter a race that can not see the color yellow (that means that greens and oranges are out too). Aside from changing the middle stop light and some of our caution signs, we wouldn't have to do anything special if we cared if they were comfortable here. However, if they saw via radio waves (not a good choice since most things would be pretty hazy or transparent to them), then they would be very annoyed with the bight flashy lights we carry in our pockets (cell phones). [Answer] The answer its simple and pretty obvious: They will encounter exactly the same difficulties colorblind people find in comunicating with other people and vice versa. So wait until someone who experienced this in first person will give an answer. Also one specie will find it easier to cheat and to go agaisnt the law in some specific cases or be better at some jobs. [Answer] You might need two sets of signs, computer monitors and stop lights. A color contrast that is clear to one species might appear a flat color to the other. There could be whole aspects of fashion that are literally invisible to the other species. in the case of humans and aliens, perhaps the aliens literally cannot see the differences in human skin color, but our hair or eyes might wary wildly to their perception. It might also be useful in engineering, like how Geordi from Star Trek was able to see things that were invisible to the human eye. [Answer] The implication of sensing different wavelengths would be most pronounced in what we try to hide. If a species can see into the infrared spectrum, it would be able to see heat through mundane obstacles and thus the significance of homes and clothing as means of personal privacy would be thwarted. Likewise, a species that can see UV or infrared but can't see into the visual spectrum might gain privacy via heat shields or UV-filtering that would seem very Emperor's new clothes to us. ]
[Question] [ Say we have a country whose foreign policy with its neighbors is mostly defined by conquest. In a period of two decades the borders of said nation encompasses hundreds of different cultures and languages, many of whom can't tolerate being close to each other, let alone living within the same political boundaries, and now they are even more angry that they have lost all forms of sovereignty. The nation has expanded to the point where over 70% of the population is not of the same ancestry as the conqueror and has technology comparable to that of Germany in the 1910's. Assuming this country does not nab any more land for itself, how could it keep itself from imploding in the long run? [Answer] # This is the Austro-Hungarian Empire Austria-Hungary was an amalgamation of the Duchy of Austria and the Kingdom of Hungary under the Habsburg Dynasty, which ruled as Holy Roman Emperor also from the 1500s. The Emperor's line came from German stock, which made up 23% of the population (in the 1910 census). In 1848, due to the low population of Germans, the Emperor had to give the Hungarian minority (about 20%) its own Parliment. The Emperor also held a third major dynastic title as kind of Bohemia (Czechs where 13% of the population). So the 'ruling' people were barely 1/5 of the total population. There was a lot of nationalist resentment at the Germans pushing their language on everyone else. When the Hungarians got their own parliment, the nation became functionally tri-lingual: all administration had to be carried out in German and Hungarian and whatever the local language was (Czech, Croatian, Polish, Ruthenian, etc). Ultimately, this didn't [work out well at all](https://en.wikipedia.org/wiki/Austria-Hungary#Dissolution). You mention the 1910s; well Austria-Hungary didn't make it out of the 1910s, dissolving at the end of WWI. # Its Russia too! For another comparison, the Russian empire of Tsars was peopled by about 44% Russians in the 1897 Census. It too failed due to the stress of WWI, collapsing in revolution in 1917. The various parts went their own way for a while, but eventually everything except Poland was reunited with the Soviet Union by the early 1920s. The Soviet Union, you may have heard, didn't prove to be long term stable either. # And the Ottomans, maybe? The Ottoman Empire was certainly polyglot in the late 1800s, but by th early 1900s it had lost much of its non-Turkish parts. The official census from 1914 makes it 80% Muslim, but doesn't distinguish between Turks and people who would not consider themselves Turks, such as Albanians, Kurds, and Arabs. In any case, the Turkish population was definitely low in the early 1800s when there were several million people in the Balkans and millions more in Egypt that were part of the Empire. # Conclusion The time around 1900 was a bad time for polyglot empires. They generally fell apart on their own, and whatever stability they had was wrecked by World War I. None of the highly multi-cultural/multi-lingual empires of Europe survived. I think it is safe to say that your Empire is doomed, especially if they get pulled into a great power war. [Answer] Divide et impera? This is more or less the scenario the Roman Republic invented that policy for. So you can just copy the solution they used. Roman history is well documented and easy to use as a reference. Extra points because after the Roman Republic successfully integrating Italy and the italic people using this policy, the succeeding Roman Empire went on to rapidly expand even more. Also in stuff related to conquest or military matters copying the Romans is rarely a bad solution. The basic concept of this policy is that instead of system where the Empire rules its subjects as a group, the Empire takes the time to have one on one relationships with the subject states. The subjects have their own identity, their own relationships, their own problems, their own solutions. They are separate entities with the biggest common thing being subject to the same Empire. The idea is that the subjects do not form cohesive groups large and powerful enough to challenge the Empire. This may require splitting previous states or coalitions by force. It may require bribery. Either directly by giving money to local leaders or indirectly by giving preferential treatment. It may, and usually does, include banning subjects from having relationships with each other or especially with outsiders. It may include replacing leaders with outsiders or with weaker or more pliant locals to make subjects weaker. Abusive taxation or tribute can be used for the same. You can then give the wealth to local strongmen to make them loyal and the nation weak. As the above should make clear their are lots of methods. It can be said that one of the key points of divide et impera is to keep up the diversity not only to split potential rebels but to assure that you always have lots of options to deal with issues before they get out of hand. Using a large array of approaches also helps keeping the situation fluid and diverse so that divide et impera keeps working. [Answer] ## Your Empire is a [federation](https://en.wikipedia.org/wiki/Federation)/[confederation](https://en.wikipedia.org/wiki/Confederation) of free democratic ethnic states\\. Through the history, there were very few [nation states](https://en.wikipedia.org/wiki/Nation_state). The majority of the people were ruled by some other ethnicity. For instance, consider the large Europian countries in 1900: one can argue that France is the only fully established nation-state. Germany & Italy are very new nation-states, United just a generation ago. While the Austro-Hungarian Empire, Russia, Ottman Empire, the UK & Spain are multinational (albeit the last two are long-standing and fairly assimilated at this point). Also, notice that there are few democracies on this list. *So, your country needs to position itself as a liberator* - "we do not conquer lands, we free people!".** After the conquest, it should establish democratic, ethnically homogeneous, states with a high degree of autonomy (and influence on the federal government). The notion of a fully independent nation-state is unknown, and thus it will not be seen as a half-measure, but as an extremely positive development. And, if you conquer a nation-state (or a region that is stelled by the dominant ethnicity of the former country) you can always sell "democracy and the rule of the people". ]
[Question] [ Previously, a [treaty](https://worldbuilding.stackexchange.com/questions/100133/aerial-surface-assault-without-bombs-explosives) was signed that effectively banned air-dropped bombs, and military versions of rockets and missiles. That treaty leaves a gap as far as Depth Charges go, and this is not precisely an oversight. The treaty was heavily influcenced by older-fashioned surface fleet Admirals and several centuries of tradition, and two weapons threatened that: Aircraft and submarines. While they didn't want to limit submarines (Since that would limit their own and, at the end of the day, they're still ships), they wanted to leave open methods of dealing with enemy submarines. This, of course, leaves the opportunity for an enterprising individual to come up with the idea of using depth charges against surface ships, potentially even some designs dedicated specifically to such a device. In my research, I haven't come across any surface vessels that were sunk by depth charges, although numerous were damaged - Often by anti-submarine craft sinking and having their prepped depth charges go off. Is it possible for a depth charge (Of any practical size) dropped by an aircraft to sink a significant surface ship, such as a heavy cruiser or battleship? Modifications to enhance weapons specifically for this purpose are allowed and encouraged. Edit for some clarifications: A torpedo utilizes active guidance and propulsion. Neither of these are allowed by the treaty. A mine is often, but not always, tethered to the seabed, and all mines (for the purposes of this definition) explode based on contact or proximity. Mines are not explicitly banned, but their uses are sufficiently different than depth charges that their use by aircraft should fall under a separate question A depth charge has no active guidance and no propulsion systems. Additionally, for the purposes of the treaty, they are detonated when they reach a specific depth, as opposed to on contact with the ground or a vessel. [Answer] ## You are looking for a bouncing bomb ![enter image description here](https://i.stack.imgur.com/kRxN1.jpg) A bouncing bomb or a skip bomb would fit your criteria. They were dropped from planes flying at low altitude and would 'skip' across the surface of the water and detonate. They were used during World War II to destroy [dams](https://en.wikipedia.org/wiki/Operation_Chastise#Concept) and [ships](https://en.wikipedia.org/wiki/Skip_bombing). These bouncing bombs fit under all of your criteria because: 1. They are essentially repackaged [depth charges.](https://en.wikipedia.org/wiki/Bouncing_bomb) 2. They have no active guidance or propulsion. They rely on their momentum to move across water 3. They are detonated by a timer, not by impact. [Answer] Technically speaking, the battleship Ostfriesland, which was sunk by Billy Mitchell in 1921 in a watershed event, went down due to depth charges. They didn't necessarily plan it that way, but when they were dropping bombs on the battleship, quite a few missed the ship by a few feet and detonated in the water next to it. It was those explosions that punched holes in the hull and eventually sank the battleship. The bombs that hit the upper decks of the Ostfriesland didn't do a great deal of damage due to the battleship's heavy upper deck armor. Something similar happened in the last case of a battleship sinking another battleship without assistance from other ships or aircraft, when USS Washington sank IJN Kirishima in the Guadalcanal campaign. While Kirishima was greatly damaged by the 16 inch shells that hit the upper decks, it was the underwater hits, shells landing just short of the decks and continued under water to strike the hull, that caused it's capsizing, as those hits tore open the hull under water, unbalancing the ship to a degree that couldn't be addressed with counter flooding. Those underwater hits occurred because Washington had closed to within 8000 yards of Kirishima undetected before opening fire (point blank range for 16 inch naval rifles), so the shells were coming at a fairly flat trajectory. Those shells that landed short just kept on going. Another form of weapon operated on the same principle as a depth charge, that an explosion in water does a lot more damage than an explosion in air due to the greater density of water: mines. While they were positioned under water to avoid detection, in practice they did far more damage to a hull than a bomb of similar size exploding in air. A lot of ships in war time have been sunk with mines. [Answer] # Depth charges used by aircraft this way will be called torpedoes The closer a plane flies to an alerted enemy ship, the more intense the anti-aircraft will be. Pilots don't want to die and planners would like to keep their loses low. You don't want to have to drop explosives directly against the hull or deck of a ship. Having some way to move the explosive charge from further out towards the ship would be really nice. Such a device will need to have a minimal frontal cross-section to cut down on drag. It will also need to be fairly long to house the detonator, explosives, primitive guidance system and motor. A propellor at the back will provide thrust. Fins at the rear will also provide control surfaces. A device shaped this way will be able to travel a considerable distance before detonating. The Mark 48 torpedo has all of the above features; packing almost 300kg of explosives. Whether detonating against the hull or against the hull of the target, it will do considerable damage. ## Political Considerations Why on earth would any sane sovereign power give up the ability to use any kind of modern weapon? That kind of a situation seems highly contrived and ripe for cheaters to keep going while those who obey the rule sit back and lose ground. [Answer] # Depth charges used against surface targets are called mines There have always been aircraft deployed mines, [up to the present day](https://www.globalsecurity.org/military/systems/munitions/mk62.htm). They principles of operation are similar to a depth charge, except instead of a pressure fuse, they will have a magnetic or contact fuse. [![enter image description here](https://i.stack.imgur.com/N6fUh.jpg)](https://i.stack.imgur.com/N6fUh.jpg) As for whether or not mines can sink large ships...well, [Wikipedia has a list for that](https://en.wikipedia.org/wiki/Category:Ships_sunk_by_mines). Here are four battleships: [Alfonso XIII](https://en.wikipedia.org/wiki/Spanish_battleship_Alfonso_XIII), [Bouvet](https://en.wikipedia.org/wiki/French_battleship_Bouvet), [Hatsue](https://en.wikipedia.org/wiki/Japanese_battleship_Hatsuse), and [Peresvet](https://en.wikipedia.org/wiki/Russian_battleship_Peresvet). [Answer] One form of depth charge used during WWII was called the "[Hedgehog](https://infogalactic.com/info/Hedgehog_(weapon))". Given the rather poor ability of early SONAR (British "ASDIC") to localize the position of a submarine, the Hedgehog projected a pattern of smaller depth charges at the suspected location of an enemy submarine, using a "[spigot mortar](https://infogalactic.com/info/Mortar_(weapon)#Spigot_mortar)". The depth charges were fired by contact fuses rather than hydrostatic fuses, with the intention that a strike on an enemy sub wold be far more devastating with the explosion in contact with the hull, rather than the hydrostatic shockwave a conventional depth charge relied upon. [![enter image description here](https://i.stack.imgur.com/ZwIDS.jpg)](https://i.stack.imgur.com/ZwIDS.jpg) Typical Hedgehog arrangement Now, while the range of such a device is rather short, the idea of firing a large number of contact fuzed projectiles through the air does allow you to attack a surface ship, with the potential of having explosive damage on the deck and superstructure, the hull above the waterline, and even potentially below the waterline as well. More powerful projectors would allow more range, but also greater dispersion of the pattern. Showering a large number of similar devices from an aircraft (or even an airship, don't forget blimps were used as convoy escorts during WWII, although mostly to spot enemy U-boats on or just below the surface) in a bombing run provides a better chance at both surviving the attack and damaging the ship. Although each individual bomb in a hedgehog strike is small, a large number of hits spread across the ship could put a lot of systems out of action and overwhelm damage control parties, especially of the attack can be followed up in close order by either more of the same or by more conventional anti ship weapons. Another means of delivering a large depth charge like projectile (or an actual depth charge if you have the ability to locate a submarine at a distance) would be a [Dynamite Gun](https://infogalactic.com/info/Dynamite_gun). Using compressed air or gasses, this was used to launch early high explosive shells with a gentle acceleration, since the violent acceleration of conventional propellant could cause the HE filler of a shell to spontaneously detonate inside the gun. Large versions could launch 15" (381mm) projectiles 2-5000 yards (1800-4600m), which is more useful, although still easily outranged by conventional artillery. The compressors and other equipment make for rather large and unwieldy weapons. A smaller version, using a captive piston and small explosive charge to generate compressed air "on the spot" was developed, but had a correspondingly short range as well. [![enter image description here](https://i.stack.imgur.com/Ce6UD.jpg)](https://i.stack.imgur.com/Ce6UD.jpg) Example of the Zalinski dynamite gun ]
[Question] [ A few of my previous questions have mentioned that the colonists to this world will be scrambling to get whatever foods they can grow, because the planet's fauna is largely nonexistent (There's sea life, but not much else) and the flora offers little to no nutrition due to different biology. With that in mind, I want to make sure the foods I do provide my people don't have them dieing of malnutrition. Keep the following assumptions in mind. They are firm and any changes to them are outside of the scope of this question: * Growing sufficient quantity is not an issue. * Genetic Diversity is not an issue. * Sustainability is not an issue. * Native flora/fauna can provide calories, but no nutrition. * The list of items is complete and embodies the entirety of the food types available. * Source is not an isssue. * Foods not listed are not available (See below, though). Now, for the list of foods available, and some uses I've found for them. In no particular order: * Barley: Can be ground into a gluten-containing flour to make breads and similar items. Also can be used for some alcoholic brewing such as beer, and is used in some soups and stews. * Flax: Flax is a super-useful plant, capable of being used to make Flax Milk, a milk substitute, and can replace eggs in many recipes. It can also be used for making vegetable oil, and flaxseed sprouts can be eaten and are slightly spicy. Linseed Meal (The byproduct of making oil) is also a good food for rabbits. Flax is also useful for a variety of non-food products. Flax flour can also be used to compliment barley flour and/or corn flour, but isn't gluten-containing. * Corn: Aside from regular corn and, potentially, popcorn, Corn can be used to make cornmeal, corn flour, corn starch, corn syrup, and corn sugar. On this world, there will be breeds of corn selected for sugar content, as sugarcane or sugar beets are not available. * Lemons: Lemons are used in turning Flax Milk (And, in reality, other non-dairy "Milks") into cream, butter, and the like. Lemons have also been used with baking soda, before baking powder was invented. * Coffee: Coffee can be cooked into things, but I'm really not sure what. * Green, Red, some spicy peppers * Tomatoes * Cucumbers * Radishes * Green Beans * Lettuce * Peaches * Potatoes * Dill * Fennel * Sesame * Rabbit meat * Snake Meat * Mouse meat (Although, admittedly, mice do not provide much meat...) * Various types of yeast (Bread yeast, beer yeast, etc) Can these foods provide enough nutrition to sustain people appropriately? If the answer is "No" I would like to know what is missing, and if you're feeling inspired, a food that would fix the deficiency while still being able to be easily grown from a seed that is stored and would possibly be on a space vessel. As a few of these items wouldn't be common items, I'm not terribly worried about realism as that can be explained by "A crewmember had a plant/seeds" etc. Any additional animals will not be considered due to other plot constraints. [Answer] # Lets run down the list of nutrients [Here](http://nutritiondata.self.com/facts/cereal-grains-and-pasta/5678/2) is a link to nutritiondata.self.com, which has nice color graphics of all the data available from the USA. That link is for hulled barley. We can check all the major vitamins and minerals and such to make sure you are getting enough of what you need; and preferably from multiple sources. You don't want single crop failure to endanger the community. ### Protein There is plenty of meat, and barley is a decent source as well; less so corn. A significant gap in this diet is actually vegetable protein sources. Specifically, there are no legumes, like beans, chick peas, or the like. However, you mention green beans. These are the same species as common beans like kidney, pinto, and navy. The difference is, the green bean is the immature seed pod, while the mature dessicated seed pod provides the latter beans. Those beans are a very good protein (and many vitamins and minerals) source; so if green beans are available, common beans will be to. ### Fiber Beans and barley are both great sources. Sesame seeds and various certain lettuces can contribute as well. ### Dietary fat You actually only have two sources of fats. There isn't a lot of nutrition data available on snakes and mice, but I believe they are both pretty mean. Fat is a necessary part of the diet, so you will have to press sesame and flaxseed oil, and use it. Flaxseed oil is one of the few good vegetable sources of Omega-3 fats, so that is good as well. Again, depending on how fatty snakes and mice are, this might not be a problem at all. ### Vitamins A, C, E, K Vitamin A comes from vegetables that are orange, as a general rule. You don't have any really strong sources, so your people will need to eat a good quantity of tomatoes and peppers to keep up with this requirement. Another option is red-leaf lettuce; the reddish pigment is partially made up of vitamin A. Peppers and lemons are a very strong Vitamin C sources, with tomatoes, radishes and peaches also useful. Vitamin E in the $\gamma$-tocopherol form is covered by corn and vegetable oils, although both your oils are not great sources. Vitamin K is plentiful in anything green, so fennel, cucumber, green beans, and especially lettuce. Leafy greens are more nutritious the more bitter they are so kale/mustard greens > romain/butter lettuce > iceberg. Iceberg lettuces is basically fancy water. ### Vitamin B-series This series is Thiamin (B1), Riboflavin (B2), Niacin (B3), B6, Folate (B9), and B12. Grains and legumes cover this well, so barley, corn and beans here. Barley is particularly good at Thiamin, Corn at B6, and beans at folate. B12 is harder to come by, but plentiful in red meat, so your people should be fine. ### Minerals Calcium is something of a problem. There are a bunch of mediocre sources, but good sources like milk and milk products, tree nuts, and fish don't seem to be available. Women at all life stages, pregnant, nursing, and during menopause need a good supply of calcium. Making it worse, lettuce is a pretty poor source of calcium compared to spinach or kale. An option here is to grind up rabbit/mouse/snake bones and use them as a dietary supplement. Iron is available from beans, greens, and red meat. The rest of minerals are available in high quantities in barley and corn. If those are your stable crops, you will have a good base of minerals. # Conclusion Calcium seems like the thing that would most likely be in demand, for women especially. As mentioned, grinding up bones would be a reasonable source of it, or just mining it from chalk formations. It shouldn't be that hard to supplement. For all the other vitamins and minerals, there are one or two food products that are excellent sources, and several reasonable sources. I would not foresee any dietary problems. ]
[Question] [ Assumptions * One habitable world in each system (blue sun system and yellow sun system). * The two worlds are fundamentally Earth-like. * The native humanoid species on each world are genetically compatible. * A native of the blue sun system visits the world in the yellow sun system. Question Would the blue-sun-alien perceive light on the yellow-sun-world in the same way the yellow-sun-native does? [Answer] It might depend on if your natives are human and just live there over several generations, or if they took a different evolutionary track. On earth, being able to pick out camouflaged creatures is actually [EASIER if you are colorblind](http://www.nature.com/news/2005/051205/full/news051205-1.html). This is the reason why [South American primates](http://www.slate.com/articles/health_and_science/science/2016/06/the_monkeys_of_south_america_evolved_to_be_color_blind_perhaps_because_it.html) tend to be colorblind. It might not just be about lighting either. It might be about environment. Here on earth green environments are the norm, so we adjusted for that. But on your blue sun planet, it might be a different story: [![http://www.solstation.com/life/a-plants.htm](https://i.stack.imgur.com/XIWvz.jpg)](https://i.stack.imgur.com/XIWvz.jpg) Because of this, natives from the yellow sun system may have different advantages than blue when they switch worlds. It might be possible that one or the other may be considered to be "colorblind" on the other planet, and this may confer advantages and disadvantages respectively. The races might be genetically compatible, but even here on earth, there are differences from person to person. And it's been postulated that we don't even [see color the same way from person to person](https://www.huffingtonpost.com/quora/do-we-all-see-the-same-co_b_5831158.html). For example, you and I are taught that a particular shade is "red." We may, in fact see slightly different shades, but since we both know THAT shade as red, we both call it the same thing. When it comes to red-green color blindness, it's more marked. For hunters tracking prey, not being able to see the difference actually makes those who are colorblind in that way better at picking out animals. This may be why, if men were the main hunters and women the main gatherers, more men experience colorblindness of this kind, and more women can see differences in shades (because this was more important when it came to judging ripeness when gathering). Those on the blue planet might even see differences in color that the yellow planet folks can't and vice versa--so natives of either may consider most of the population of the other planet colorblind. Because there is a lot more to the spectrum than we can see, and there are even animals on this planet that do not see what we can, but can see colors we cannot readily perceive. While you may believe that because they are genetically compatible that your two populations will see colors in the same manner, consider this fact: within our own population there are differences in how we see color, even when people are genetically compatible. Take that to two different planets, and there may be even more of a difference. [Answer] If you have ever had to fight with lighting in a video studio, you will know the frustration that ensues because your eye is self adjusting for white balance. When you look at he scene in real life, whites are white. Look at it on the video monitor, and everything is red because of the tungsten lights. After an adjustment period (a few minutes to a few hours) your visitors would perceive colors exactly the same as a native. [Answer] If the humans have the same structure in their eyes, which can be assumed by the fact that they are genetically compatible, the color of the sun should have no effect on their perception of the world. There might be cultural differences based on what colors are significant important on either world. But that affect is more a function of culture/language than it is a function of the star itself. For example in English we have consider red and pink to be distinct colors. While other languages don't consider pink to be a distinct color and would refer to the colors we call pink as light red. ]
[Question] [ Theoretically, assuming it was possible and practical to take a particle accelerator and turn it into a gun/cannon weapon, and use it to shoot accelerated subatomic particles. What sort of subatomic projectile would cause the most damage? Assuming for a moment that the technology in question is powerful enough to break the strong and weak nuclear force (and not just turn the weapon into a straight up bomb), what would make the biggest bang for your buck. protons, neutrons or some other particle? As in, what would affect the atoms of your target and create the greatest detonation? Another point of my question isn't what subatomic particle is the best bullet, but rather what subatomic particle when shot at a target can better destabilise the targets atomical structure, kind of like the "Little doctor weapon from the movie and book Ender's game" that shoots a sort of energy beam at a planets ring system and disintegrates it on a molecular level. And finally, how would it work (from a theoretical standpoint, what would it do). [Answer] The ever useful Atomic Rockets has a section on Space Warfare ["conventional weapons"](http://www.projectrho.com/public_html/rocket/spacegunconvent.php) which has most of the details you need to understand particle beam weapons (and almost every other type of weapon). Short answer: ain't happening, hoss..... Particle beam accelerators use the property of ionized particles to manipulate the particles, both to accelerate them, focus the beam and direct the beam. So long as the beam stays inside the accelerator, all is good, but open the port and let the beam escape, and the mutual repulsion of the particles will cause the beam to rapidly dissipate, as high energy electrons, protons or ions rapidly fly away from each other. During the 1980's, as part of the Strategic Defence Initiative (SDI), two ideas surfaced which might allow the use of particle beams in space and in the atmosphere. 1. Neutral Ion beams. This isn't some mind bending alteration of the laws of physics, but rather the ion beam from the accelerator was to pass through a cell of some neutral gas and strip electrons from the gas to neutralize the beam. The highly charged and fast moving (relativistic) beam would enter the cell, and emerge moving slightly slower but with the charge largely neutralized. This didn't solve all the problems, and the beam was calculated to sell spread out due to thermal blooming, but you could get a few thousand kilometres range. Of course with 80's technology and launch platforms, each neutral particle accelerator would take many flights to build, and be giant targets floating in orbit. [![enter image description here](https://i.stack.imgur.com/Vg7Fd.gif)](https://i.stack.imgur.com/Vg7Fd.gif) TRW concept for a particle beam weapon. Image via [Scott Lowther](http://www.aerospaceprojectsreview.com/blog/?p=1352) 2. Electron beams for ship defence. The US Navy considered the problem of shooting down incoming antiship missiles, and concluded that an electron beam would be a good weapon, being able to deliver lots of energy to the target, both thermal energy which might cause structural failure to the missile airframe, and the electrons themselves would damage any onboard electronics. Since the atmosphere would absorb the beam, and the mutual repulsion problem would make the beam useless at all but the shortest ranges, the concept was tweaked to have a high power laser fire first. The laser would create a partial vacuum along its path due to the energy being deposited in the air, and the electron beam would naturally follow the channel. The full physics escapes me (the fact the beam ran down a channel of partial vacuum allowed the beam to remain focused for a much greater distance than otherwise), and you might also reasonably ask why not just use the laser to shoot down the missile. As of 2018, the Navy has answered "you know, why not use the laser?" and prototype laser weapons are now being installed on ships. Now there is one way to utilize a particle beam to make an effective weapon capable of being used both in the atmosphere and in space. Use a very high power electron beam to drive a Free Electron Laser (FEL). By varying the power output of the beam as it passes through the "wiggler" magnets, you can vary the wavelength of the laser beam which emerges from the optical train, going for very short wavelengths utilizing small mirrors or diffraction gratings for space, and stepping down to infrared or other frequencies which fire through "windows" where your atmosphere is transparent to the wavelengths for surface combat on a planet. [Answer] Anti-matter Anti-particles would get you the most bang, so to speak. They'd also react with the air. So, you could come up with some sort of containment to make them last longer, like a pulse of anti-electrons surrounded by a large number of protons, or just have an anti-matter flame thrower that spews them continuously. But you'd need a good shield since you'd be closer to the weapon than the target would be, and it wouldn't go very far. Neutrons The best travel, the best mass, and if the target is made of the right material you could trigger a fission or fusion reaction. But most things are not affected by neutrons and they would pass right through. Protons or electrons Instant plasma! Protons have more mass, and may follow a straighter path, but both will immediately interact with particles nearby. If you had a lot of them flowing in the same direction you'd ionize a path, creating a beam of plasma. Crazy high energy needed, and it might form a fractal pattern more than a straight line. You might have some sort of laser that guides the plasma or pre-ionized the path of the particles to reduce the spread and energy loss, but it's pretty far from understood physics and would require a bunch of handwaving about the mechanics. Alpha radiation Using ionized helium nuclei would have more mass and a straighter path, and could have instant negative effects on DNA, similar to alpha radiation from plutonium. Alpha radiation is stopped by a sheet of paper or other similar minimal barrier, but if you had enough of it going fast enough, you could cut a path. This would probably be like a death ray, creating an ionized beam that is particularly destructive to organic material. Still very short ranged and very ionizing, but a reasonable fuel source would be a canister of helium gas. [Answer] Answer: radon. A particle beam weapon would be good for shooting something where you did not want to burn a hole in it, but rather wanted to deliver energy to something inside - perhaps a lifeform, or some element of a spaceship. The precision (in 3 dimensions) would minimize damage to the rest of the target which might be desirable for various reasons. It might be less likely to blow up. Or you could salvage it. Or you could disable a ship without punching a hole in the side and killing the crew. As background consider what real particle beams are used for. Conventional radiotherapy uses photons which is electromagnetic radiation. Particle radiation has the benefit that a moving charged particle unloads its energy mostly at the point where it slows down. from <http://radcare.org/types-of-radiation-therapy/particle-beam-radiation-therapy> [![proton vs photon radiation](https://i.stack.imgur.com/kGOuf.jpg)](https://i.stack.imgur.com/kGOuf.jpg) So a particle beam is good for depositing energy at a specified distance into an object, and that energy deposit site (here a tumor) can be governed by adjusting the amount of energy put on a proton. Other ions are used for particle beam radiation. One hears about carbon ion radiation and I see that other particles (neon, krypton) have been tried. from [The Emerging Role of Carbon-Ion Radiotherapy](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4894867/) > > While conventional radiation generally passes continually through a > biological target, with dose delivered roughly equivalently throughout > the beam path, particle beams release energy at the inverse of their > velocity. Particle beams thus deliver a lower entry dose, depositing > the majority of their energy at the flight path terminus, yielding an > asymptotic dose peak (the “Bragg Peak”) (15). This allows for a dose > concentration distribution impossible with conventional irradiation > methods. > > > Today, proton dominates particle therapy. However, the larger mass of > carbon results in decreased beam scattering, yielding a sharper dose > distribution border with minimal penumbra (16). Radiobiologically, > carbon-ion beams result in two to three times the relative biological > effect (RBE; the biological effectiveness of one type of ionized > radiation relative to another, given the same amount of absorbed > energy) of proton and conventional irradiation methods > > > So the more massive the particle, the more kinetic energy and the more precise the beam? Apparently not. <https://www.bnl.gov/nsrl/userguide/bragg-curves-and-peaks.php> is an excellent reference on Bragg curves, which depict energy deposition at given depths for a charged particle with a given energy. [![braggg curves](https://i.stack.imgur.com/i7XEX.jpg)](https://i.stack.imgur.com/i7XEX.jpg) From that site > > When the primary ion of high-Z breaks up, it results in several low-Z > fragments, each of which deposits small amounts of energy in the > material. The sum total of all the energy deposited by all fragments > can never add up to the energy deposited by the primary ion. This > causes the Bragg Curve for fragmenting high-Z ions like Iron to drop > initially. > > > So heavy ions like titanium and iron and gold which fragment do not cleanly bring their energy to a given depth and drop it off - they fragment and deposit energy along the way sort of like electromagnetic radiation. Sloppy. Carbon must not fragment like that and neither do xenon or krypton. I presume xenon and krypton do not because they are noble gases but why that should be true (or what governs the tendency to fragment in a given ion) is beyond my ken. So: more massive = more punch, and noble gases are less fragment prone and more likely to deliver the energy at the depth you want. Radon is the heaviest noble gas and so that is my answer. --- Addition in case you want to use this in an atmosphere and the air is in the way. 1: Shoot a dart with a conductive wire. 2: Turn the wire into plasma with a huge electrical charge. It will in essence be a horizontal lightning bolt. 3: The expanding plasma will leave a low density core of near vacuum. It will be where the wire was. 4: Discharge your particles down this transient vacuum path. ]
[Question] [ Clearly, I don't mean simply keeping eyes on a target ship -- unless of course there was some method by which one ship could remain within visual range of another without being seen by the target. I just don't think there is, and I don't want to resort to magic to solve this issue. So what I'm looking for, in a nutshell -- is there a method such that one ship could observe another without revealing itself? I've considered (for my story) using trained birds, but I'm not sure how plausible that is. [Answer] Early in WW2, the German Navy experimented with a small gyrocopter that was towed by a surfaced submarine. It could reach a height of a few hundred feet, greatly expanding the visible area to the observer flying the gyro. The gyrocopter was small enough that it would have been essentially invisible to ships at any distance. Never very successful, it also committed the submarine to being on the surface, and the possibility that in the event of attack, they might have to cut the gyrocopter loose and dive, leaving the observer on the open ocean alone. Along those lines, it is theoretically possible to use a towed balloon in the age of sail... by the early 1800's, lighter than air gases had been used to carry a balloon aloft to increase the range of an observer. If the balloon were painted light blue or gray, it would have been difficult for opposing ships to spot at any distance. As far as I know, that was never actually done in a naval setting. In WW1, some of the Zeppelins carried a small gondola that could be lowered with an observer, for use when the airship was above an overcast sky. They'd lower the observer to below the clouds, and have them report back what they saw. It wasn't used for tracking ships, but could have been. However, that would only work as stealth observation when an overcast sky was present. Also early in WW2, the Imperial Japanese Navy had refined night time naval operations to a very high standard, both attack and observation, aided by excellent night optical gear... binoculars with very large objective lenses to amplify the available light. Using this, they were able to ambush an Australian and American fleet in the first Battle of Savo Island, sinking four cruisers with no losses. So excellent night optics could be another way to track ships without being observed... but only at night. Edit: to show the flip side, the Japanese reliance on night optics came back on them at Guadalcanal, during the Night Action of Nov 14. IJN battleship Kirishima, along with some cruisers, were closing to bombard Henderson field, and had set fire to a couple of US destroyers, while also battering US battleship South Dakota. The flames from the burning destroyers blinded the night optics, masking the approach of USS Washington (who was using radar to track the Japanese fleet). Washington was able to close to within 8000 yards of Kirishima without being seen - point blank range for 16 inch naval rifles - and wreck it with several broadsides. Kirishima capsized and sank the next morning. This incident is also notable for being the last time that a battleship sank another battleship in combat, with no assistance from other forces. [Answer] Take an age-of-pirates or age-of-Napoleon ship. (Technically, ship would refer to a ship-rigged vessel, not just any large watercraft.) The masts consist of separate spars mounted on top of each other, with yards holding the separate sails. [Here](https://en.wikipedia.org/wiki/Topmast) is a typical mast with main mast, topmast and topgallant mast, and [here](https://upload.wikimedia.org/wikipedia/commons/7/79/Balclutha_main_topgallant_mast.jpg) are the yards. The convenient lookout positions are where the mast sections and/or yards meet. Often there would be a small platform, called a [top](https://en.wikipedia.org/wiki/Top_(sailing_ship)#Fighting_top). Note that the top is not at the tip of the mast, because there would be no conventient ropes to hold in bad weather. In good weather, lookouts would detect the sails of another ship well before the hull of the ship comes over the horizon. But that's not certain, in bad weather the detection might come much later. So if [the uppermost sails](https://commons.wikimedia.org/wiki/File:Square_rigged_sails.svg) of a ship are not set, there is a good chance that the lookout would miss the bare masts, at least at long distance. This suggests several options: * Send a sailor to climb as high as possible, above the height of the usual tops, and adjust the speed of the pursuing vessel so that the target's royal or topgallant sails are just over the horizon. With luck, the own royals and topgallants are just below the horizon. * As above, but strike the royal and topgallant sails and possibly even their yards (naval crews were trained to do that at sea). The pursuing vessel would have to keep up with the target on main and topsail alone, which makes this problematic. * Use a spare spar (warships would carry several on the [spar deck](https://en.wikipedia.org/wiki/Spar_(sailing))) to extend the height of the mast and get a higher lookout post. This wasn't normal practice because the lookout position would be rather uncomfortable, especially in high winds. All these options depend on the height of the observer relative to the own sails, so they don't depend on having a large ship. It would be possible to use a [sloop](https://en.wikipedia.org/wiki/Sloop-of-war) or the like, or perhaps a schooner. [Answer] What technology period are we talking about? During the first world war, naval ships 'saw' each other over the horizon by looking for the smoke plume. Coal fired boilers produced huge pillars of black smoke. So it was easy to track them at a distance. If your ship used wind, then it could stealthily follow such a war ship. As long as there was wind. ]
[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/87147/edit). Closed 6 years ago. [Improve this question](/posts/87147/edit) In my world, there has been a zombie apocalypse at some point in the past. Humanity got hit hard by it, and the number of humans has been reduced to a few thousands when it happened. Humanity managed to actually win against the zombies over time, since there was a huge but limited number of them, and they are pretty dumb. Now the human population is back within the millions (it's been decades, maybe even centuries, I haven't decided yet). We are rebuilding civilization slowly but surely. Obviously, zombies didn't fight among themselves or eat each other (that would make any sort of horde impossible, therefore making them no dangerous at all). They aren't particularly interested in eating brains, but do love eating humans. They would probably eat other animals in they managed to grab them. Only humans can be turned into zombies. They act basically like in The Walking Dead as for moving slowly, going after survivors by sound, sight and smell, but you need to have had contact with a zombie (bite, scratch, etc) to turn into one. You don't turn if you die from other causes, but your dead body can be turned later on if it gets scratched or bitten. Now from a realistic perspective, even though they are technically dead already, zombies move. They need bones, muscles and energy to do so, even if they are almost brain dead, and don't seem to feel pain or bleed out from cut limbs. A human that gets turned probably has calories to keep moving for a few days, maybe weeks if he has lots of fat. Catching something and eating it will obviously result in a calorie intake (they can diggest you assuming they still have the necessary organs, and this can probably be handwaved if they don't). Let's say that zombies show up on day 1, and reduce the world population through kills and turning them into zombies to a few thousands within 5 years. How long can I expect zombies to stick around after that, assuming humans are now well organized and almost nobody gets turned anymore? I'm looking for the very maximum length of time that there could still be a few zombies around, and what exactly did those outlier zombies do in order to last that long. For example, if the majority of zombies died within 1 year, almost all of them are dead after 3 years, and maybe a few dozen of them can still be found after 5 years. What did those last ones do differently to last so much longer? Did they happen to be in a specific location, or were "asleep", etc. Where did they find the energy to live so much longer, and of course having an idea of how long this would be is good, but that's not the main question. In this context, I want to set my story up so that everyone knows about the zombie apocalypse, but do not expect to find zombies anymore, but end up finding one or a few of them at some point, which take them completely by surprise (unexpected), but is still possible. [Answer] So you want your zombies to be actual dead people. The only parallel I could think about are jellyfishes. Jellyfishes are bloodless, heartless and brainless moving creatures. Close enough to a zombie for us to compare them. Because your zombies lost their blood and therefore cannot carry oxygen and nutrients to the muscles for your zombies to walk, they won't be able to hunt anything and they won't even want to because their brain is dead as well. > > The thing is, while jellyfish don’t have a brain or central nervous system, they do have a very basic set of nerves at the base of their tentacles. These nerves detect touch, temperature, salinity etc. and the jellyfish reflexively respond to these stimuli. Since they don’t have a brain, they live passively, depending entirely on their automatic reflexes. > > > First, we should understand exactly what a heart does. It basically pumps blood around the body so that the cells of an animal can get oxygen and nutrients from the blood and expel soluble wastes, like carbon dioxide. However, what is special about the jellyfish anatomy is the thickness of the outer layer, known as the Ectoderm. It is only a few cells thick, so oxygen simply diffuses into the jellyfish body. [source](https://www.scienceabc.com/eyeopeners/jellyfish-function-without-heart-brain.html) > > > Zombies have holes everywhere so oxygen can travel directly to their muscles. Muscles are not a few cells thick so they'd lose a lot of muscle power. Don't expect them to do anything except crawling and faintly scratch someone. Oxygen won't just magically go into your muscle tissues so you'll need something to diffuse oxygen into your zombie which we'll get to later > > Jellyfish also have a very rudimentary digestive system, where simple nutrients merely diffuse into the rest of the body. > > > When your zombie has no more energy, he'll start to crawl then just lay on the ground and go into hibernation mode. The idea would be to have your zombie bury himself in plants and dirt in order to pump the nutrients out of it. Maybe your zombies have a symbiotic parasite that pumps and processes nutrients for your zombie keeping it "moving" while the parasite uses the zombie to spread to other humans. I told you about the cordyceps a fungus which invests an ant's brain and controls it towards leafs where the ant is to hang to and die until a branch pierces out of the ant's skull and releases spores. This fungus has a secondary metabolism which creates antibiotics for the ant to keep it from multiple infections while it hosts the cordyceps. [source](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis) Here are a [few videos](http://www.bbc.co.uk/nature/life/Cordyceps) of the cordyceps' effects. If instead of antibiotics the cordyceps were to produce glucose then you have a way to power your zombie pretty much indefinitely. The bigger problem comes from the state of decay in which the zombies are and would result in them falling apart within a few weeks of infection (depending on the weather). It would also mean that zombies would not survive inside buildings and cities outside of green spaces. Your zombies will likely not look human anymore. Not even in the shape of a human because of the fungi growing off their bodies. How the cordyceps went from the brain of a very specific species of ants to any human brain will have to be hand-waved because it is impossible (or would take millions of years of evolution). But this is the closest I can get you. By working on senses and reflexes alone like a Jellyfish and with the help of a symbiotic parasite (likely a fungus) you could have something close enough to a "real zombie" which would grow roots to feed themselves in the absence of humans to eat --- Edit: I jumped the "would that be enough energy part for now". Since you are very vague I do not want to go through all the energy conversion formulas before I even know if this is a fine concept for you. (And also I don't have enough time at this very moment. Will edit later if this satisfies you) [Answer] I will offer what may seem like the "obvious" answer, in retrospect: Zombies burn their existing fat and are cannibalizing their own body. This includes cannibalizing their own brain (through biological processes, not grabbing pieces of it) which is mostly fat. We do the same through exercise and starvation (and if we run out of fat, our body starts burning our muscle tissue, which is how we become emaciated). I would guess one reason Zombies want brains is for their fat content; and perhaps Zombie digestive functions have been compromised to the point that it doesn't let them digest anything but fat. This has some measure of plausibility; fat is already converted into an easy to access energy storage unit, that is why we get fat. So it is easy to break down. [The brain is the fattiest organ in the human body;](http://articles.mercola.com/sites/articles/archive/2009/01/22/fascinating-facts-you-never-knew-about-the-human-brain.aspx) consisting of at least 60% fat. An adult human, as food, offers about 100,000 calories. If Zombies need maybe 1000 calories a day (slow moving, little brain function, little healing or other bodily maintenance), their own body could sustain them for about 100 days. By then, other Zombie bodies will have been burning through their calories and offer little sustenance. So once the regular humans run out; along with dogs, cats and cattle, give the Zombies four to eight months before they start dropping dead. (again, this time for real!) They drop dead when their metabolism, like a brain cancer, finally dissolves whatever neurons were left in their brain that was coordinating their movements. ]
[Question] [ I'm working on a science fiction story involving starships travelling about 95% of the speed of light. I wanted to have a reason for the starships to need to shield themselves against time dilation of any significant amount. Primarily I want this for story-writing purposes, so that you could have fast starships—fast slower than light ships—without the complications caused by time dilation. I'd like justify this with reasonably hard science... Could there potentially be any unwanted material effects due to time dilation and/or Lorentz contraction? One idea is this; when a force—such as thrust from an engine—is applied to any material that force will propagate only at that material's speed of sound. Consequently as a starship accelerates, the atoms in the front will always be travelling a little bit slower than the atoms in the back (or vise versa if the ship has its engines in the front). This would mean that the atoms nearest the engine would be experiencing slightly more time dilation than those further away. At high speeds with pronounced time dilation, could this lead to a weakening of the starship's structure? While there might be no, or nearly no effects if space were a total vacuum. In practice space is full of rarefied gas and dust—not to mention the quantum vacuum. This paper might be helpful in regards to extreme relativistic effects: [link](http://www.sciencedirect.com/science/article/pii/S0094576517300371) TL;DR I don't want the complications of time dilation but still want fast sublight starships. Is there any justification to screen out time dilation from a structural integrity stand point? Could time dilation and/or Lorentz contraction cause structural problems? [Answer] In general, there are no effects doe to being at speed. We are travelling at 90% c from their point of view — does that suddenly make things happen? Now moving through space at high speed has real problems because the oncoming gas and dust will be near lightspeed, and lorentz contraction of the path you’re on will make you see a higher density of material. As for acceleration, you might find [Bell's Spaceship Paradox](https://en.wikipedia.org/wiki/Bell's_spaceship_paradox) interesting. Instead of two ships and a chain, consider the front and back of a single ship. But again, your high speed has nothing to do with it; it doesn’t get worse as you get faster. Rather, it has to do with acceleration, and you're not accelerating more than 1G I would presume. And remember the equivalence principle! The same effects of a 1G acceleration are manifest in skyscrapers here on Earth! That is, nothing you would notice without delicate instruments. [Answer] The whole point of relativity is that there should be no way to tell how fast you are travelling, because there is no absolute speed. There can be no effects from travelling fast, because if there were then relativity would be violated. [Answer] There are no, absolutely no, structural effects or defects caused by traveling close to lightspeed. The main problem encountering gas or dust in interstellar space. A forward shield or barrier will be needed for astronaut safety. The main complication with time dilation for a writer is calculating how much time is different between the astronauts in the spaceship and the people who remain on Earth. The physicist John Cramer in an example about a spaceship travelling close to lightspeed came up with a simple way calculating the time for the astronauts. Assume the spaceship accelerates at one gravity (1 g) for one year and reaches a cruising velocity of 0.867 c (86.67% of lightspeed). Time dilation will be two. Let the spaceship travel 86.67 light years which take 100 years for it to do so. At a time dilation Lorentz factor of two, fifty years pass in the spaceship. It now decelerates for another year at 1 g. The total time in the spaceship will be two years for the acceleration and deceleration phases combined plus fifty years ship time. A total time of 52 years. In the relative rest frame of reference for Earth, and presumably for their destination, the time it has taken the spaceship to undertake this trip will 102 years. You can further assume during the acceleration and deceleration phases the spaceship travels a distance of half light year for each phase. The total distance travelled 87.67 light years. The alternative is travelling sufficiently fast to go places, but not so far as to large amounts of time dilation. A velocity of about half-lightspeed it achieve this effect. The time dilation is 1.1547. Calculate the time it take a given distance at 0.5 c, which is simple just double the distance travelled, and divide by 1.0635 to work out the time passed for the astronauts. Then another year for the acceleration and deceleration phases. Time dilation can be the friend of science-fiction writers who want fast, slower-than-light travel. Find a friendly person who knows enough to do the calculations for you. ]
[Question] [ We have a species, let's call them Aves Sapiens for now, which a winged creature that reaches an average height of 143 centimeters and can fly up to 300 km/h. (Assuming that the planet's gravity can support it). They have the intelligence of modern humans, along with similar social behavior, and their most advanced civilizations is similar to the Roman Empire at its height. With all of this in consideration, what would be the most efficient way for them to design cities? [Answer] One thing flying civilizations have to deal with a lot more than us is building generated updraft. Going after some old memories and a single bbc article (I currently don't have the time to search more, didn't know about the corners) there are three big factors: * height * distance between buildings * and sharp corners <http://www.bbc.com/news/magazine-33426889> So I would expect rather wide streets, since you don't have a lot of foot-traffic-only paths anyway. Prevalence for ramps over stairs, since again you are more concerned with cargo than foot traffic. More circular housing blocks. maybe around a park/lake or up the sides of a hill. Buildings where the floors are layered in wide terraces, which give room for easier start and landing. Also you have to decide if there exist regular nonflying visitors, which would need extra accomodation [Answer] While it might be tempting to design birdhouse-like structures, consider that civilized creatures (i.e. not struggling for survival against elements and predators) will probably be lazy. And flying is a lot of work. And if they're anything like humans, there will be hoarders who want to move lots of heavy stuff into their homes. Also consider elderly and disabled, which isn't a thing in the wild because they die, but would be a real concern for a civilized species. I would think that maybe the architecture would have birdhouse-like impressions to it, but that there would probably be ramps or pulley systems for goods, and likely walkways between levels. Also, keep in mind that building vertically will always be more expensive than building flat, because vertical structures require more design and stronger materials. Although, for these residents a story is probably only 6-7ft and it doesn't need to hold nearly as much weight. unless they like pottery. To imagine a city of these people, I'd guess that the wealthier residents live in artfully designed multi-story houses with stone/earthen bases and wooden pole construction for 3-5 stories. Less wealthy residents probably have 2-3 story dwellings, and maybe the poorest residents are stuck making nests in the hills around the city, with the poor elderly and/or disabled ending up at the bottom of those hills, and young "street rats" ending up at the top of the hills. The homes would probably have very small windows, or barred windows, since any large opening could essentially become a door for a burglar. Walled garden type things wouldn't probably exist since the wall would serve no purpose. All angles of the home would be visible, so if they had stuff they didn't want seen it would need to be inside or underground. All homes will likely have large sturdy roofs, to protect against falling objects (imagine the common occurrence of accidentally dropping goods or equipment from several hundred feet up, or those weekend parties when everyone is flying home drunk and can't be bothered to find public toilets) Lightweight creatures probably don't have endurance for too much digging, so basements are probably rare. For moving the quantities of food needed for a city, boats are probably still the most efficient method, so a sizable city would probably still be along the water. That said, a creature that can move so much faster than a human might be able to fly out to nearby farms for meals, so they wouldn't be as reliant on supply chains like humans are. But, don't underestimate the space needed to grow enough food for the population of a city. [Answer] It is difficult to give an idea if You don't develop some infrastructure first. In general I would think to something like a series of "apartments" with balconies for take off and landing. Something like [this](https://commons.wikimedia.org/wiki/File:Birsay_colony.jpg#/media/File:Birsay_colony.jpg) :) Wealthy people would live in the upper floors where they can reach the skies without need to escalate the busy canyons between buildings. Problem with this setup is Roman Empire technology required heavy tooling difficult to transport in flight. In fact also Roman products (warfare and other things) tend to be heavy and unsuited for use by flying creatures (most likely obsessed with lightweight); something like the "eggshell ceramic" from ancient China would be better. Did they invent the wheel? Do they have carriages? Who pulls them? animals? Are they plying [oxpecker](https://en.wikipedia.org/wiki/Oxpecker)? If so then You need some ramps at least in the lower layers of the "urban cliffs". In general You need to think a bit better this society which is bound to be much different from what we know and surely different from Roman Empire ;) [Answer] Here is some idea based on [Doraemon: Nobita and the Winged Braves](https://en.wikipedia.org/wiki/Doraemon:_Nobita_and_the_Winged_Braves). We have technology before industrial revolution. Bird want to live harmony with nature. They build house inside a tree. How to get in and out depend on species habit. House could be multi-story (inside large tree) that they go in and go out from balcony, or mid-air door (like dove nest). Or door on the ground as our house if they are not so perfect at maneuver. Transportation: They are flying, of course. With technology of pre-industrial, they could hardly craft anything faster than themselves. However, a glider may help them rest their wing on the long run, or carry good. For example, 3 birdy carry one glider full of good. If you want some fantasy/steampunk, you can add flying bicycle, a bicycle with one (or more) fan. But there are so much aerodynamics to explain. [![Flying bicycle](https://i.stack.imgur.com/oY8ID.jpg)](https://i.stack.imgur.com/oY8ID.jpg) Mean of transportation also depend heavily on domestic animal they have. Domestic animal Bird-men use domestic animal to do work for them, like human. If their are flying animal can carry heavy load, then birdman would you them. First, pack-bird (well, like our pack-horse). Then, they invent something to carry more load, like glider for big-bird. However, if bird-men can only find domestic (horse, donkey, ...), then they should develop same technology human have to utilize those animal (pull cart ...) [Answer] # Where do lots of flying critters live? First, we should investigate where large colonies of flying creatures live right now, since those would probably be the sorts of places that your civilization would develop. Some ideas: * Lots of bats live in caves. No pictures necessary. * Lots of flying fox bats live roost in trees together. [![enter image description here](https://i.stack.imgur.com/48C2A.jpg)](https://i.stack.imgur.com/48C2A.jpg) - Lots of seabirds make huge ground colonies called rookeries. [![enter image description here](https://i.stack.imgur.com/1Hwo9.jpg)](https://i.stack.imgur.com/1Hwo9.jpg) * Lots of both seabirds and other birds nest on or in cliff faces. Here are carmine bee-eaters: [![enter image description here](https://i.stack.imgur.com/BF6F0.jpg)](https://i.stack.imgur.com/BF6F0.jpg) * Finally, multi-familiy weaver birds make some incredible nests: [![enter image description here](https://i.stack.imgur.com/jepJ8.jpg)](https://i.stack.imgur.com/jepJ8.jpg) # What features are in common? * Ability to take off. All except the rookery let you jump out into the air to take off, so no difficult ground launch. This would be even more important for a sentient flier, as I imagine they would be larger and heavier than any of the birds/bats here. * Protection from predators. Also relatively important, even for a sentient creature at the top of the food chain. Can you imagine flying while pregnant? A flying creature probably could not give birth to a baby as large and well developed as ours. Flying creatures would need to lay eggs like a bird or give birth to very undeveloped young. Young would need protection from predators, even while still at a neolithic level of technology. The iron age wouldn't be so far along that the strategy of building protective shelters would be forgotten. -Nearby food source. The rookery and seabird cliff homes are near the open ocean and fish. The flying foxes are near seasonal fruit blooms. The cave bats and bee eaters eat bugs, while weaverbirds are generally seed eaters. What is your species going to eat? What is their strategy for farming/domesticating their food source? That is going to make a big difference. [Answer] Flying creatures will sure use all three dimensions. Houses with entrances in different directions. Trees and structures like trees. Houses as nodes/"nests" on those "trees". Many structures (furniture) will resemble trees. Booths will look almost the same, only they will hang on trees instead of standing. Market will be a set of concentric spheres, with holes in them, covered with goods. Slaves will be much easier controlled - cut wings will be enough. They will be very useful, for they will carry heavy goods by ground. Our cities on free place grow like snails - by spirals. That world picture depends on the fact of existence of supertrees. If they don't exist, cities will have really only 2 dimensions and the third will be used in a limited way. Among great trees cities could become really 3d. ]
[Question] [ If you think about it, the reason why we are able to kick is because of how our leg bones (in addition to the rest of our skeletal and muscular systems are set up) are designed. A biped, humanoid digitigrade race on the other hand, might have trouble because of how their skeletal structure is set up. We happened to be a plantigrade species which means our digits, or toes, are flat on the ground, while a digitigrade species walks on its digits, like a cat or dog does on it back legs. In my research, I found mention of this: the GURPS Traveller books talking about the Vargr who are a biped, digitigrade species of humanoid wolves. It said that Vargr weren't able to kick because of their digitigrade leg and feet structures. However, if look at this picture here (PLEASE NOTE: the webcomic creator is known for toon nudity (i.e. Bugs Bunny or Chewie the Wookiee). Just to give you some fair warning): [![enter image description here](https://i.stack.imgur.com/g1tCE.jpg)](https://i.stack.imgur.com/g1tCE.jpg) That digitigrade wolf was able to kick that human. While it is possible that the webcomic creator may have used creative licensing (and he has been known to do that from time to time actually) and just wanted the page to look cool, if you look at how the wolf is positioning his leg: it's held up. Now, this is a stretch, but the panel makes it look like he is swinging his body around like a top in order to kick the human, meaning that his leg isn't held straight out in front of him, but straight out to his side. Again, this could be creative licensing on the webcomic creator's part, but there are ways to kick someone, knee kicks being one example actually. So, this all boils down to the simple question again: is a digitigrade biped humanoid species capable of kicking someone or even kicking at all? Please note, this question is not looking at whether digitigrade animals can kick, but how a biped, humanoid digitigrade species would be able a kick if they can, or if they can't, why can't they kick? Nor is the question looking at how hard a biped, humanoid digitigrade race can kick, and it doesn't matter if the species is mammalian, avian, insectoid, fungoid, etc. *We are looking at whether a digitigrade, biped, humanoid species/race can kick at all, and if it can how? And if it can't kick, why can't it kick?* [Answer] All the large ground birds can kick to lethal effect, it is their primary defense and they are all digitigrade. Rhea even have sharps spikes on the back of the legs to do more damage. Creatures with such legs won't be able to do a human sweeping low kick (their knees would have to pass through each other), but they can do a forward kick and side kick, likely with more force in the former. Heck an ostrich can kill a lion with its kick, and only weigh around 200lbs. True your creatures are not birds but that really will not matter for the ability to kick, the birds are just an example of a living bipedal digitigrade. As long as they don't have a rod and socket hip joint like dinosaurs they will be able to kick just fine, and even then they could kick forward. if they can bend over they can forward kick, if they can splay their legs they can side kick. bipeds in general have to have good balance and they have very strong legs compared to quadrupeds of the same size. If you want an animal with the same leg proportions dromaeosaurs evolved to kick as their primary form of hunting, they cannot kick to the side but that is due to the strange hip structure dinosaurs have, no dinosaur splay their legs either, even the quadrupedal ones. [Answer] It would probably depend on their muscle structure and balancing abilities. Obviously the muscles around the calf and foot are going to be different, but if the muscles of the thigh are the same as a human's, a roundhouse kick like that seemse feasible. They could strike with the knee, shin, or top of the foot region. With most good kicks, the force comes from the hip and thigh, so most human kicks seem anatomically possible. The problem I see is balance. Having toes and heels on the ground at the same time is a huge advantage when kicking. When humans (and, I presume, ostriches) kick with one foot, the foot that stays on the ground grips the earth with its heel and toes for balance and stability. A horse can kick because it has four legs. That means it still has three very distant contact points with the ground to keep it steady. A digitigrade biped might have some trouble because it only has four toes touching the ground. That's four contact points, but they're all small and very close together. Without a heel to anchor them, human-like kicks will be rather wobbly in a creature like this. The solution: flying kicks. If a digitigrade biped jumps (which its leg structure should enable it to do quite forcefully), it could kick in midair with one leg like a Tae Kwon Do master, or with both legs like a kangaroo. The force of the jump would add to the kick, and they wouldn't have to worry about balance, just a sturdy landing (which would be easier with two feet, or two feet and a hand). There would be a slight disadvantage to this in that you could see these kicks coming from a mile away and have more space to dodge or block. But hey, Tae Kwon Do wolves. [Answer] Kangaroos are digitigrade and can kick from a bipedal position, although they "cheat" by bracing themselves with a heavy tail on the ground, making them effectively "tripedal" while kicking. Still, said kicks are capable of breaking bones or rupturing organs, so yes, it's possible. Youtube has a video of a "boxing" match between kangaroos [here](https://www.youtube.com/watch?v=WCcLMNcWZOc). ]
[Question] [ How could humans survive underground for centuries? People have built multiple underground facilities around the world to prepare for a catastrophe. Just to be careful they overcalculated their resource needs. However they didn't expect their surface samples to contain a new deadly disease. They decide to wait out the disease, but this takes centuries, maybe even a millennium. How would these people live sustainable? What would they eat? How could they expand? Also what about sunlight and other problems? * Imagine a late 21st century civilisation, about 50 years from now. * The groups that went underground are the elite, as such they consist mainly of scientists and rich folks. Billions of dollars go into the creation of these facilities. * Multiple hundreds of people should fit in one facillity. * They had enough time to prepare so they might have some livestock and vegetables. Maybe they could practice some form of underground agriculture? * The disease is vaccine proof, so "vaccine and resurface" solutions are not possible. I already have a way to keep it alive on surface so also no "wait until the disease has no host and dies out" answer works. I just need to know how they would stay sustainable for a thousand years. [This answer seems to already solve how to get water](https://worldbuilding.stackexchange.com/q/30245/34389) although is this still possible with an air + waterborne disease? [Answer] Water They could easily get by with recycling and searching for underground lakes and springs. They only need digging equipment, consumables (for recycling) and power. [Where would water come from in an underground colony?](https://worldbuilding.stackexchange.com/questions/30245/where-would-water-come-from-in-an-underground-colony?noredirect=1&lq=1) Food They could grow lots of things in the caves that they would excavate. For example, see here: <http://ask.metafilter.com/262998/Grow-food-in-a-giant-cave>. Still the issue is digging equipment, consumables (nutrients) and power (light/air/etc). And that's it. Marginal survivability ensured by food and drink.However, 1000 years is a long time!Colony or simply Refugees? You need to ensure reproduction and increase of the population. How many fertile women? In-breeding? You should take care of initial setup of population, or your colony will be dying out after a few generations. Check: [Smallest Self-Sufficient Colony](https://worldbuilding.stackexchange.com/questions/48376/smallest-self-sufficient-colony) Initial Logistics Power! As already stated by other answerers, there are ways to provide - but you should. As well as tons of consumable materials for food/drink processes, tools, and digging/excavation equipment for expansion. Psychology How will the enclosure affect human psychology and society? Will it drive them crazy maybe, never seeing the Sun again? Maybe go schizo and kill each other? Or, why not? New Generations Young people are never satisfied to accept things as they are. THey will puch forward changes and splinter groups. How will they conform, rebel against, or in general drive the societal evolution? Evolution Mutations that fit better the underground environment willl appear. Skin color will change. Eyes will adapt to darkness and artificial lighting. Being tall will not be desire in the short underground passages. They will become some kind of fantasy dwarves in 100o years?*But they will all die out, in the end.* Because in the premise of the question, they only entered the underground shelters to survive the catastrophe. Their initial supplies and preparedness were made according to that assumption. They were never prepared for spending one thousand years in hiding. They only discovered about the unstoppable virus afterwards, when it was too late... [Answer] Simplistic answer: Your underground bases run on nuclear power. They have enough fuel stockpiled for a long time. Nuclear power run lights, thus agriculture. More complex answer: They die. The problem is you have too small a population to maintain all the skills needed to keep the society going. [Answer] Two of the best things for survival aside from water sources would be nonperishable foods and frozen foods. Sources containing vitamin C and D would be essential, since humans cannot produce their own vitamin C, and lack of sunlight could be combated with vitamin D. Mushrooms are an excellent source of the later. (All vitamins are essential.) Source of power might be resolved with geothermal energy. The scientists might find a way. Smaller energy sources could rely on batteries. I know you said the disease is vaccine-proof (and be sure it's incurable and untreatable, since vaccines are applied before illnesses), but what about hazard suits? If this is permissible, then perhaps solar energy could be installed. I think filtration could assist with purifying contaminated water. How resistant is this disease to heat? Perhaps an alternative could be boiling the water. ]
[Question] [ I am working on a scenario that begins with an impact event. I have multiple questions, but I'll start with the catalyst for this world. Is there a type of impact event that would not be a global killer, but basically poison the air, forcing humanity to live in shelters for a few years, while allowing vegetation to (at least some degree) survive? The World: The world I am creating forces humanity into shelters, where they can resurface in a few years in protective gear, leaving behind a, still vegetated, but drought-like surface. I'd like a realistic scenario to allow for this, ideally stemming from an impact event. [Answer] Global [Lake Nyos](https://en.wikipedia.org/wiki/Lake_Nyos) event. [![enter image description here](https://i.stack.imgur.com/GRfnc.jpg)](https://i.stack.imgur.com/GRfnc.jpg) from <http://www.neatorama.com/2007/05/21/the-strangest-disaster-of-the-20th-century/> From Wikipedia > > A pocket of magma lies beneath the lake and leaks carbon dioxide (CO2) > into the water, changing it into carbonic acid. Nyos is one of only > three known exploding lakes to be saturated with carbon dioxide in > this way, the others being Lake Monoun, also in Cameroon, and Lake > Kivu in Democratic Republic of Congo. > > > In 1986, possibly as the result of a landslide, Lake Nyos suddenly > emitted a large cloud of CO2, which suffocated 1,746 people[2] and > 3,500 livestock in nearby towns and villages.[3][4] Though not > completely unprecedented, it was the first known large-scale > asphyxiation caused by a natural event. > > > The premise for your event: it turns out the climate change deniers were right. Rising CO2 was not man made but due to a gradual, colossal outgassing of CO2 at one site at the bottom of the ocean. Like Lake Nyos, immense amounts of CO2 accumulate. When the meteor hits that area, the water outgasses and a Nyos-like "cloud of doom" rolls over the earth. Animals suffocate. Plants chortle merrily, replete in delicious CO2 and loads of nitrogenous fertilizer. Not only do they survive, they thrive. Some humans make use of tunnels and other CO2 free air to survive and ride out the trouble. I am struggling some to figure out how to make this last years. The Lake Nyos event lasted a couple of hours tops. CO2 can definitely kill you and you could throw in a fair proportion of CO which kills you better. But a continued outgassing from some secret source so as to keep the surface uninhabitable strains my credulity. You could have the CO2 arrive from space - a giant frozen dry ice meteor. A lot. Most of it would sublimate away on entering the atmosphere, creating the "cloud of doom" - a really big meteor but not a really big impact. The rest would turn to gas from the heat of the impact. You could have enough CO2 arrive that it would take a long time to disperse. CO2 is also good because it is not cyanide or something immediately deadly. It is more interesting and offers more story opportunities to have the atmosphere be bad but not outright lethal - people who had to venture outside would feel sick and hyperventilate as their CO2 level rose and pH fell. The plants would not just survive - many would thrive. Also, there is plenty written about what other things would happen with high CO2 - icecaps melt, poison ivy takes over etc. All of that stuff would happen in fast forward. Humans would emerge into a green, hot, wet, itchy world. [Answer] The meteor could hit the yellow stone national park volcano, trigger a huge ash cloud. The ensuing fire and loss of sunlight (plants dont like darkness for extended periods of time, or so I am being told) could be enough to create on other continents a poisonous atmosphere. Fires, created via looting, and burning oil reserves will increase the ashcloud density and size as well as the C02 concentration. ]
[Question] [ For the purpose of a story, I would like to imagine a system of two Earth-like planets orbiting like Earth and Moon. I imagine that these planets were created by a gigantic collision at the beginning of this stellar system between two planets. One of these planets traps quite all the iron and metals, and the other stays with a small iron nucleus. Both of the planets have Earth-like atmosphere and have developed life. Is this kind of system realistic? [Answer] It's not entirely implausible for two earth like planets to form this way, [The giant impact hypothisis](https://en.wikipedia.org/wiki/Giant-impact_hypothesis) is after all almost exactly what you described. The one limiting fact that I see is that were one of the two bodies to end up with most of the iron (and by extension nickel) then the planet may not be able to generate a [magnetic field](https://en.wikipedia.org/wiki/Magnetosphere). The movement of the molten metal core forms a [geodynamo](https://en.wikipedia.org/wiki/Dynamo_theory) that produces the magnetic field which protects the atmosphere from the solar wind. Without the magnetic field, the solar wind will [strip](https://en.wikipedia.org/wiki/Atmospheric_escape) the atmosphere from a planet. So if the world with the small iron core did develop earth like conditions they may not last long. All other things being equal, the planet lacking the large iron core will also have a lower mass and by extension gravity than the other. Earth's core is about [1/3](https://www.quora.com/What-percentage-of-the-Earths-mass-is-contained-in-its-iron-core) of the mass of the planet. While not that big of an issue it does pose problems for gaining and holding onto the atmosphere especially when being blasted by the solar wind. As for their orbit, they would orbit like the earth-moon system. This means they orbit a [Barycenter](https://en.wikipedia.org/wiki/Barycenter), the center of the masses of the two planets. For the earth-moon system that point is beneath the crust of the earth so from a distance the moon orbits the earth while the planet wobbles. Given the likely dissimilar masses the orbits may look like the pluto system: ![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Barycentric_view_of_Pluto_and_Charon_29_May-3_June_by_Ralph_in_near-true_colours.gif/230px-Barycentric_view_of_Pluto_and_Charon_29_May-3_June_by_Ralph_in_near-true_colours.gif) In summary, the system is not unrealistic. The two planets would have large differences in their masses and one would likely have a thinner atmosphere. But they could have earth like conditions and evolve life. [Answer] A "binary planet" setup is totally plausible. The Moon is already not all that much smaller than the Earth, and the Pluto-Charon system is even closer in size. Simulations of giant impacts sometimes find close to equal-sized planets orbiting each other. It would look something like this: [![enter image description here](https://i.stack.imgur.com/esHy9.gif)](https://i.stack.imgur.com/esHy9.gif) Wikipedia even has a page on "double planets" [here](https://en.wikipedia.org/wiki/Double_planet). And I used them to build systems with lots and lots of planets in the habitable zone: see [here](https://planetplanet.net/2014/05/22/building-the-ultimate-solar-system-part-4-two-ninja-moves-moons-and-co-orbital-planets/) and [here](https://planetplanet.net/2014/05/13/building-the-ultimate-solar-system/). [Answer] <https://www.space.com/27832-binary-earth-size-alien-planets.html> THEY SIMULATED IT "These binary planets would loom extraordinarily close to one another, separated by a distance of about half the diameter of each of the worlds. Over time, the rate at which both planets spin would fall into lockstep, with each world only turning one face toward its partner." ]
[Question] [ Note: The word scripture itself technically means writing, and "other media besides text in scripture" is an oxymoron, but here I am using the word to mean something like "sacred media". I was watching the series Cosmos by Neil DeGrasse Tyson (itself a remake of Carl Sagan's series from the 70s). Although supposedly a science documentary - I couldn't help but notice the frequently reverential and mystical tone that Tyson takes when explaining things, and the way he treats the great scientists of history with prophetic like reverence. In the final episode, he includes a recording of Carl Sagan's famous ["Pale blue dot"](https://www.goodreads.com/work/quotes/1816628-pale-blue-dot-a-vision-of-the-human-future-in-space) quote, followed by a series of injunctions by Tyson himself to be an open minded, self-critical free-thinker, and to cherish the environment and the planet - the tone was very reverential. It's almost Tyson intended the series to be some sort of religious instruction material for those who believe that science has all the answers. This led me to wonder: Past religions' scripture has always been in text form, but that's because historically the only way to keep long term records was in writing. But technology now allows to keep other media in long term records as well. Is it conceivable that future religions would include not just sacred texts, but other media as well? Would they include sacred video, sacred audio, sacred binaries, sacred computer code, etc....? What would such a future religion look like? [Answer] Imagine that some future scientific experiment absolutely proves the existence of God. For example, imagine that an advancement in the current imaging technology which is currently visualizing individual atoms, someday reveals a copyright notice or an artist's signature on every subatomic particle. The video tapes of that first enlightening moments, and the early repetitions of that experiment could easily be called sacred. I personally think that the video of our first step on the moon (sans the silence) is sacred footage, and when the vibration from the approaching mother ship in "Independence Day" obliterated Neil's footprint... That was sacrilege. [Answer] The key to this is your misapprehension that text has always been the only medium. In practice every available medium was used. Of course limited options were available, but your most notable missing ones are either carved in stone or oral tradition. Even monotheistic religions like Judaism have both written and oral traditions. Both of these options have problems. An oral tradition is dependent on continual survival and continuity of population, it also suffers from a high level of corruption with the generations. If people move away from the homeland they move away from the tradition or carry an incomplete tradition with them. If the population is decimated, a considerable portion could be easily lost. Stone carving also has a problem with mobile or displaced populations simply in that vast statues, carved monoliths and henges are not particularly portable. Again it suffers compared to the relative portability of the written text. Your future religion is going to have a similar set of problems when deviating from written text. The most obvious being compatibility of hardware, backward compatibility etc. There's something enduring about the written word that we don't yet have with digital media. What would happen if your missionaries took their stacks of CDs to a planet that used laserdiscs, minidiscs or VHS. It's a dead loss for spreading the message. A book is recognisably a book, no matter how old, a scroll or carved stone tablet the same, but what is this shiny circular thing with a hole in the middle? Books have one last advantage. When lost and alone, in the cold and dark on a strange world, you can use it to start a fire and be saved in a much more literal sense. However this loss of accessibility is not necessarily a bad thing in the long run. Consider why you might want the original text of your religion to be largely inaccessible to the people. Religions are born in a time and place, in a specific culture. The rules and customs don't necessarily have any relevance at all thousands of years later in a galaxy far far away\. Having the text be inaccessible means that the priest (or otherwise) can "interpret" the text to the age in which they're living, keeping the spirit of the religion up to date in a way that the ancient text can't manage. \Who seethes a kid in its mother's milk anyway? [Answer] ## Absolutely Yes If other forms of media besides text like pictures existed back when a major prophet was around there would definitely be pictures taken and when a group like the [Council of of Nicaea](https://en.wikipedia.org/wiki/First_Council_of_Nicaea) rolls around they would decide which versions of which pictures would be the best to include in the religious documents. This would of course lead to controversy over why they did not include certain pictures in the holy text much like we see today why certain letters and prophecies that are not included in the Bible. ### Experts in Ancient File Types Including things like images would lead to problems as file types change over time (much like languages do). We have people who study ancient Greek and Hebrew so that they can read source documents. In your world I see there being experts who study archaic and ancient file types like bmp, png, and jpg. They would help interpret old files and translate them into whatever the file types are of the current generation. This would lead to various versions of the images much like versions of the Bible. This would lead to people saying things like this: > > Personally I prefer the jp2 edition, it has the best interpretive algorithms for accurately rendering the image. > > > Or > > If you want to truly understand the images, you have to look at the original bmp of the image. All other versions do some amount of interpretation to get those higher resolutions, and so will never be as accurate. > > > ### Study Images Much like how there are study Bibles, there would likely be study images. These pictures would have annotations on them to point out subtle details in the images. They could include variations of color correction and filters to help highlight and draw attention to minor background events happening in the picture. [Answer] Anytime Now Right now, people have video blogs for their preaching and sermons. It is very probably that an entirely independent, new, 'following' will arise and be on Youtube/Internet as early as today. New Age just barely missed the boat on being founded on Youtube (and the Internet) although they certainly use that media. Smartphones, computers and pads will be able to access videos, archive them, and bring them up again for historical record. [Answer] Let's back up a step. What is "scripture"? Speaking primarily from a Christian point of view, "scripture" is the message that we believe was given to us by God and that we view as authoritative to define our religion. I think many other religions would say similar things, but not all. Some religions don't really have a body of writing that they view as authoritative. But using that definition ... Religions throughout history have used media other than text. Many or most religions have created music, sculpture, painting, architecture, and theater. But I don't know of any religion that says that these non-text media are part of their "scripture" per se. That is, Jews and Christians and Muslims and others write songs or paint paintings to portray things from their scriptures or to celebrate their faith, but they don't view these as authoritative. If two Christians had a disagreement about who was present at some event discussed in the Bible, they might carefully study the text of the Bible to find their answer. But they wouldn't look to a painting of the scene or a play about the event. That wouldn't be considered authoritative, just the theory or interpretation of the person who produced that media. Likewise, religious groups in countries with modern technology routinely use radio, TV, movies, and the Internet. But these are not viewed as scripture. That said, I find it is easy to imagine a future religion considering a video of a sermon by their founder as scripture. Why not? As a Christian, I believe that God revealed things to people over the course of several thousand years, and those revelations have been collected into the Bible. Why could he not reveal further things at some time in the future? If he did, I don't see why he couldn't use movies or streaming video. (Some Christians say the Bible is now "closed" and so there will be no future revelation, but that's an entirely different question that I don't want to get into here.) "Sacred computer code" is a bit of a stretch. What would it do? Sacred accounting software? A sacred video game? A program that tracks your sins in a database? But maybe I'm just not being imaginative enough. [Answer] tl;dr. There is already modern day scripture if you look hard enough, and it seems to be approximately converging on what you say. The Church of Jesus Christ of Latter Day Saints is an example of a church that believes in receiving new scripture continuously. This makes it a good example of what future scripture would look like. [General Conference](https://www.lds.org/general-conference) talks are considered to be a form of scripture, especially if the author of the talk is a prophet. President Uchtdorf included in his talk [Fourth Floor, Last Door](https://www.lds.org/general-conference/2016/10/fourth-floor-last-door) a couple images. This may not have been produced by him, but since he included them, you could consider them part of the scripture. This is just one example; many talks are including images and even some video. Indeed, the recordings of the talk could be considered sacred videos, which go all the way back to [1971](https://www.lds.org/general-conference/1971/04). More generally, all those that produce media for the church are supposed to seek the wisdom of God in producing it. Therefore, you could consider anything produced by the Church as being impure forms of scripture. If this is the case, you have have many images, videos, and even binaries that could be inspired. They could even be canonized someday, if the prophets consider it to have scriptural accuracy. This isn't as far fetched as you think, when you consider that we do not know who even wrote all the books in the Bible. [Joseph Smith-Prophet of the Restoration](https://www.lds.org/media-library/video/2010-07-117-joseph-smith-prophet-of-the-restoration?lang=eng) has been used in missionary work for a while, after all. The prophets of the church also have social media accounts. Although not everything the prophets say is scripture automatically, they probably have quite a bit of inspiration as well. And actually, there is an even better example: the facsimile's in the book of Abraham, [Facsimile 1](https://www.lds.org/scriptures/pgp/abr/fac-1) for example. Given that it is directly referenced by the scriptural text, has an explanation that is scriptural text, was probably drawn by Abraham (given that the was an astronomer and therefore probably good at drawing), and is included in the Pearl of Great Price, which is canonized scripture, I think its safe to say that it is in fact a sacred image. The funny thing is that its actually considered to be the oldest scripture by the church, even older than Genesis presumably. The facsimiles are more of an exception than the rule though; no other currently avaible ancient scripture has images. If you want to know what future scripture looks like, the closest thing you can get to is modern day scripture. [Answer] Religions have always and will always use mediums to their best capacities, just like every other portion of society. Thus, it is not only natural that there will be scared media other than text, but in fact I think it is almost certain that there will be such media. Text can record a very coarse sense of the meaning. Poets have weaned amazing amounts of power out of these written words, but in the end they have their limits. If you had an audio recording, you can capture the intonations of the voice. Intonation has always been a very powerful thing. For example, I have been told that ideally one would not read the Quran, but experience it with the proper intonations. Intonation can capture jest and seriousness and awe and reverence in a way that text simply cannot. This is why we will sit in auditoriums to hear [JK Rowling read her books](https://www.youtube.com/watch?v=mC_wGnuc9mo) to us. We want to hear the intonations that the author intended. Video can capture even more. Interestingly enough, while we could have plenty of flashy videos designed to wow audiences, I find the subtle is far more important for conveying messages along the lines of religion. One great subtlety is in the eyes. You can see so much in the eyes of someone as they speak. I still see something utterly horrific in the dead eyes of Dr. Oppenheimer during [his famous recording](https://www.youtube.com/watch?v=lb13ynu3Iac) quoting the bhagavad gita as we ushered in the nuclear era. There's something there that to this day I cannot quite pin down in words but can experience every time I watch his face. There is an opposing trend in some places. Some groups elect not to leverage modern media for their message. Martial artists, for example, often refuse to publish videos of themselves because they fear people will try to interpret what they see when they watch it over and over and miss the intended message completely. However, this is always a transient process that results from change. We eventually find new ways to leverage our new mediums, and then they find their way into everything we do, including religion. [Answer] Yes, just as religions have in the past. To expand on Jay's statement: "Religions throughout history have used media other than text. Many or most religions have created music, sculpture, painting, architecture, and theater.", consider the use of money and architecture also. Many religious leaders are found on the coins and bills of the period, along with various religious symbols and epitaphs. Perhaps the very specific placements and alignment of buildings and monuments are part of a religious record....the ancient pyramids across the globe, Stonehenge and other some circles, burial mounds in the Americas, some other monuments designed with astronomical considerations in mind. Other media include the countless monuments and relics that pay homage to various deities in many, many countries. They are found standing or hung not only in our churches, but in our parks, schools, libraries, lawns, homes, and closets. Some might also consider our own bodies as media with the adornment of religious jewelery and tattoos. And since this question does not specify only current real-world answers, an interesting possibility could be our very own DNA as a medium. A high-tech society might be able to find a way to encode their religious beliefs right into the building blocks of our bodies. Hmmm...this is what we believe a person should look like, and the personality traits they should have, and the capabilities and limitations they should have as they strive for enlightenment.... we shall try to "write" the DNA to make this possible.... [Answer] # Existing religions are less scriptural you seem to be assuming I will argue that religions going forward will not look like the great religions of before (great meant strictly in the sense of having a lot of followers or influence). Already in the West we underappreciate the differences between the familiar religions (i.e. Christianity, Islam, and Judaism) and those of other parts of the world. Those three religions are inextricably linked to each other through their origins, and there is a reason that they are commonly conceived of as 'Religions of the Book.' But away East, Buddhism doesn't really have a comparable corpus of divinely inspire tomes (not least because they don't have a comparable view of divinity of Godhead). The same can be applied in varying ways to the other well-known or well-followed religions of the East. I am not a follower, student, or expert of those religions, so I will decline to comment further on exact differences; but suffice to say, the centrality of Scripture in the Religions of the Book is different from other religions in the world. # Modern 'religions' won't look at all like the old kind # (HEAVY CONTROVERSY WARNING !!!!!) Do you believe in global warming? Why? Some scientists published some studies about it. They have all this evidence that the world is heating up and that this is going to be a disaster for humanity and the Earth. Can you explain to me in detail why their argument is true or do you take the scientists on....faith? Do you think that people who oppose gay marriage should not be allowed to speak at public events? I mean, that is definitely mean-spirited, and it oppresses those who are gay by denying them basic rights. What is the justification for believing that gay marriage should be available to all? The moral justification is the Golden Rule, say many. Why is the Golden Rule 'true'? Here is the point: If you believe in global warming, and I tell you that global warming is a hoax; or if you believe in gay marriage and I tell you that gays should not be allowed to marry, you will likely be offended. How is your reaction any different than if I told a Christian that Jesus was a con-man or told a Muslim that Mohamed was a pig? Given the great variance in religious practices among people around the world, what is religion other than a set of commonly held beliefs held on faith? Belief that taxes or communism or government is bad, that global warming is a threat, that personal sexual freedom is good, or that anti-trans or anti-Black Lives Matters attitudes are a crime are basically that: tenets held on faith. The belief in a 'God' figure isn't really a central concept of religion, Abrahamic bias notwithstanding. Again, I am no expert, but if you take a look at Eastern religions, or even the familiar pagan polytheism of Greece or Norseland, the idea of an omnipotent god is not really that common. We have no rigorous evidence that taxes are bad, or that anti-trans people are evil, and the great majority do not have or do not understand the evidence that global warming is real. Therefore many of our strongly held beliefs have the character of religion. To answer your question then: is there a 'Bible' of global warming or a 'Koran' of gay rights? No, there is not. There is simply a set of mutually reinforcing social messaging on the topic, that spreads orthodoxy and fights heresy. You can get your modern religion through any communication medium out there. [Answer] I would say that this is already hapening the bible and other religions text has already been converted to audiobook form and they O'Lakes lots of Bible apps you can get online as technology becomesolutions more advanced they may replace the traditional print form. ]
[Question] [ This question is part of a series that includes [mosquito prevention](https://worldbuilding.stackexchange.com/questions/68789/mosquito-protection-for-an-ancient-rainforest-civilization) and [agriculture](https://worldbuilding.stackexchange.com/questions/69100/how-to-build-a-floating-farm). The environment is a rain forest basin, similar in many ways to both the Amazon and the Congo. There is a mighty river and its many tributaries that flood every year, raising and lowering the water level 10-15 meters each year. In this basin, a river civilization develops to a Bronze Age level. Edit: Editing to add more about the nature of the floodplains. This environment is like a [varzea](https://en.wikipedia.org/wiki/V%C3%A1rzea_forest), a flooded rainforest environment. The flood levels are much higher than and not comparable to any river other than the Amazon. There is almost no topographic variation (hills) and in the rainy season dense jungle covers all the available dry land. The people are restricted to the river, and the grassy parts of the flood plain, all of which are under 10m or more of water in the wet season. I imagine that this civilization will have to go to extraordinary measures to build and maintain cities. In order to keep the city high and dry all year, the city could be built on a 20m platform of limestone blocks. For example, the bases of eight Great Pyramids would provide a limestone surface of about half a square kilometer, perhaps enough for a city of 5,000. You can assume that limestone can be quarried near the headwaters of one of the river's tributaries and is then easily transported by water to anywhere on the river network. Is it feasible to build and maintain a city of half a square kilometer in these conditions (i.e. with the erosion of a massive regularly flooding river)? How big of a city could be reasonably made? What sort of innovations would these city dwellers need to make to keep their city livable? [Answer] I think stone platforms would only be used for special buildings such as palaces, temples, or mausoleums under your scenario. The elevated platform would be an integral part of the architecture of the building. This might extend to ceremonial centers, which are essentially collections of such special buildings having larger platforms shared by multiple buildings, so there might be one or two cities with parts such as you describe. But for ordinary cities, buildings and people using stone does not make sense. They would use raise buildings by stilts or by collecting earth as village mounds. Village mounds would have retaining walls of wood or stone (depending on location, wealth, and direction of flood currents) and the earth would be compressed by use and as part of mound construction. The earth would come from the canals and ponds needed to support your floating farms. You need constant water access during flood and drought and that requires moving lots of earth for the needed waterworks. The result would be an extensive network of small agricultural villages surrounded by ponds filled with floating gardens and connected with a network of canals. There would be few ceremonial centers for religion and administration which would have extensive public buildings complete with stone platforms. The best source for such civilization is probably the Khmer Empire. Their water intensive form of agriculture was rice paddies not floating gardens so the network of irrigation canals was more complex and the actual farms less complex. [Answer] There are a couple of things which are going to make it difficult for your people to make massive stone structures. 1: Lack of manpower. A lot of manpower is needed to make big stone structures (Maya, Aztec, Egyptian, Cambodian). That kind of manpower means a big population. Big population means big agriculture, which means a lot of arable land. If your folks are confined to the river their population will not be big. 2: Lack of stone. Having local stone is crucial. The quarries for these ancient structures can be seen from the structures. Mayans built with stone in the jungle but there were hills to cut the stone from. You describe an environment with no hills, which means no rock outcroppings or cliffs. Everything will be uniformly covered with deep sediment. I am thinking that a quarry not much higher than the river will run into the water table very fast. The ancient Amazonians built but not with stone. Stonehenge stones came from a distance. All the stones in Stonehenge stacked on top of each other would make a pretty puny pyramid. The idea of a Stonehenge type structure serving as the base of a wooden building is pretty cool, but the tallest stones are maybe 6 meters. [Answer] ## Is it feasible to build and maintain a city? Oh, yes, this can be done. It's a lot of work and you don't need stone at all... Setting it in a tropical area is the new part (\edit: for me). In fiction: [March to the Sea](https://en.wikipedia.org/wiki/March_to_the_Sea_(novel)) has a city in a flood plain with a lot of water. I think the city was called Diaspra. For the Exterior:* In real life: [the Netherlands](https://en.wikipedia.org/wiki/Netherlands). They have fought long and hard with water. Of particular interest would be [flood control](https://en.wikipedia.org/wiki/Flood_control_in_the_Netherlands). With your 15 meters of water you will want to scale it up a bit, but you will gain an idea about the amount of work... And you don't even need stone: > > Popular in the Middle Ages were wierdijken, earth dikes with a protective layer of seaweed. An earth embankment was cut vertically on the sea-facing side. Seaweed was then stacked against this edge, held into place with poles. Compression and rotting processes resulted in a solid residue that proved very effective against wave action and they needed very little maintenance. In places where seaweed was unavailable other materials such as reeds or wicker mats were used. > > > Just don't forget some big sluices and a way to get rid of the water during the raining season. Mills could work nicely if the winds are not to bad. Maybe use water mills? Otherwise you just have a new lake that took a lot of work. It seems the Babylonians had some ways to get water to hi-er parts. [The Hanging Gardens](https://en.wikipedia.org/wiki/Hanging_Gardens_of_Babylon) seem to be able to do so. There are ideas how they did it. But we are talking [water screw](http://www.biblicalarchaeology.org/daily/ancient-cultures/ancient-near-eastern-world/hanging-gardens-of-babylon-in-assyrian-nineveh/) technology. And that is extremely hi tech for their age. Think space shuttle when it first flew. For the Interior: Having a lot of water is good, helps with hygiene and transport. Look at [Amsterdam's layout](https://en.wikipedia.org/wiki/History_of_Amsterdam#/media/File:Map_of_Amsterdam_-_Amstelodami_Celeberrimi_Hollandiae_Emporii_Delineatio_Nova_(J.Blaeu,_1649).jpg), very useful to transport stuff without carts or beast of burden. As an other answer said, [Venice](https://en.wikipedia.org/wiki/Venice) is famous for their canals. There are more then these European examples; [Angkor Wat](https://en.wikipedia.org/wiki/Angkor_Wat). It seems it had very good [water management](https://journals.lib.washington.edu/index.php/BIPPA/article/viewFile/12016/10641) (pdf) systems. But stagnant water is very dangerous with disease and critters. And this being a tropical environment you might want to do something about big water predators. On the other hand, you have [river dolphins](https://en.wikipedia.org/wiki/River_dolphin) to play with. Oh, the options. (never mind the (giant) otters) As said in other answers, you will need a lot of people to make and hold dikes, but you surely can. They will just be very [big](http://www.tbm.tudelft.nl/fileadmin/Faculteit/CiTG/Over_de_faculteit/Afdelingen/Afdeling_Waterbouwkunde/sectie_waterbouwkunde/people/personal/gelder/publications/papers/doc/paper12.pdf). note: most of these cities were build with more then bronze age tech, so it will not be simple. [Answer] # Manpower and foundations The vast manpower requirement has been mentioned, but the foundations required will need major maintenance during the dry season. For an example of what I mean, put a rock on a sandy beach in front of the incoming tide. How long does it take before the water undercuts your rock and it sinks into the sand? Not long at all. Your foundations will either require you to dig down to bedrock or dig down deep enough that the currents over the course of the wet season do not undercut your perimeter stones. In the dry season you'll need to rebuild and refill what has been cut away, especially at any the corners where the effect will be amplified by turbulence. This is not a city that will long stand the test of time without regular maintenance. Venice is lighter than what you're considering here. It's built of brick on raised ground with wooden piles to stabilise the ground below the foundations. The city is only 600 years old and requires constant maintenance. The Dutch prefer to keep all the water out, reducing their exposure to the erosion that moving water causes. Their maintenance is equivalent to yours, while over a much larger area, it's still focused on a perimeter. I would consider following these examples: Start with a waterproofed stone perimeter, fill the inside with rubble and mud stabilised with wooden piles then build on that. This will reduce your manpower requirement to build the city down to something possibly manageable, however no matter what you do you will need to maintain that perimeter. Moving water is a relentless and unforgiving opponent. [Answer] Egypt co-existed with the Nile's annual floods (and indeed, depended on them) for maybe 5000 years, until the building of the Aswan Dam. (In the 1960s IIRC). So yes, it's quite possible. [Answer] I see no problem with this city, unless floods are so violent that they can overturn the stone blocks. After each flood, blocks will get tilted and shifted. This is Ok if the citizens would immediately go to work and get the blocks fixed. They would benefit from anchoring those blocks with piles driven deep into the ground and invention of cement. But if your city is left without maintenance for a while, its existence would be put into question. [Answer] It is entirely possible to build cities on flood plains. Giant stone blocks would definitely work, but wouldn't be the first method used. First off I would expect some hills or higher ground to exist in most all floodplains, this is where the longer term structures of a city would likely be built. These hills could be expanded and linked, either by earthmoving or with large stone blocks as you suggest. This would likely be the basis for why a city exists here at all, people could live here during flood season and a city is born. Some structures could be built on stilts, pilings, or otherwise be tall enough to be above the flood waters, these types of piling structures are very common for most coastal cities as they expand onto the water and would be likely to show up in a river port city as well. These have the advantage of not requiring anywhere near as much effort to construct, and can be built piecemeal and develop organically as the city grows. Your stone structures could also grow out of this process as some buildings build large stone foundations. A large number of structures, including those of the poor would likely be built on the lowest and least desirable ground and would simply not be built to last and would be washed away each year and have to be rebuilt each season. [Answer] As @Will mentioned, stone structures would require significant manpower, which this area is pretty much designed to eliminate. The physics check out - You CAN build on top of stone blocks and have a city get flooded under, around, etc regularly. Venice, Italy is a good example of something like this being possible, if a bit extreme. The answer you need now is not "Can it be done?" but "How was/is it done?" How do these people feed everyone? Fishing is a good start, but there's only so many fish. Do they trade with other people up and down the river? If so, then what do they trade? Is the stone of theirs of very good quality? Do they have good masons? Do they sell their fish - Perhaps one kind that only breeds around them is considered a delicacy in the town up the river. There's a lot more that needs to be answered - and asked - to truly solve this question. ]
[Question] [ Supposing that we can create an entire [synthetic being](https://en.wikipedia.org/wiki/Synthetic_life), what material would be best to make its bones of attending to: * Weight * Strength * Durability * Reparability Let's set some scenarios: Case 1: > > The synthetic being is an animal that should be able to reproduce and > grow, so it must be able to process food into "bone" material. > > > The food could be part of another synthetic animal or plant... (in that > case the second one must be able to produce it from the current > Earth ecosystem) > > > I'm especially interested in the weight/strength ratio in order to make > the biggest flying animal posible. > > > Case 2: > > Replacement for human body, this is done when the original body is not > functional (consciousness is "moved" to the new body) any needed > nutrient to repair tissues is provided in its refined form but the > organism must be able to use it in a reasonable way (heat a metal to 800 > degrees is not reasonable) > > > [Answer] There are a number of ultra-lightweight, ultra-strong materials that would be excellent for bones, if cells can be engineered to grow them: * [Ultralight Ceramic Solid Metamaterial](http://newatlas.com/llnl-ultralight-metamaterial/32589/): New materials developed by a MIT/LLNL team are as light as [aerogel](https://en.wikipedia.org/wiki/Aerogel), yet 10,000 times stronger. They aren't aerogels though, but are metamaterials. That is, artificial materials with properties that aren't found in nature. The idea is to structure it so that it has the lightness of aerogel, but is much stronger: > > "These lightweight materials can withstand a load of at least 160,000 times their own weight," said LLNL Engineer Xiaoyu "Rayne" Zheng. "The key to this ultrahigh stiffness is that all the micro-structural elements in this material are designed to be over constrained and do not bend under applied load." > > > The team sees the materials as one day being used to develop parts and components for aircraft, motor cars, and space vehicles, and that in practical use, the material could end up being 100 times stronger than the experimental versions. * [Magnesium Nano-Composite](http://gizmodo.com/new-magnesium-composite-has-record-breaking-strength-to-1749578336): Researchers from UCLA have created a new kind of metal composite made from magnesium infused with silicon carbide nanoparticles, and it’s both lightweight and super-strong. In a series of tests, the researchers have shown that, compared to materials with a similar density, it demonstrates ‘record levels’ of stiffness-to-weight ratio and strength-to-weight ratio. The team behind the new material reckons it could be used in aerospace applications, where high strength and light weight are qualities of choice. There’s no suggestion as to how expensive the nano-composite will prove, but the team does claim the manufacturing technique is ‘scaleable.’ [Answer] The problem with most suggestions for advanced materials is whether they could be grown and repaired by a biological system. Many are not at all biologically compatible: embedded in a body they corrode or cause inflammation or other adverse immune responses. We can make bone replacement implants from titanium and certain ceramics. Our biology tolerates these but cannot maintain them, and more surgery is needed when they wear out. Much medical research is directed at how to create a temporary framework that can be seeded with bone cells and implanted, to grow into natural bone with ultimate metabolism and elimination of the framework. Bone, as already mentioned by others, is comparable to.mild steel for its strength to weight ratio. It is also a living tissue, continually repairing itself so that micro cracks do not propagate into fractures (c.f. metal fatigue!) It can grow, repair after severe damage, strengthen in response to repeated heavy stress. Hundreds of millions of years of evolution may have produced the optimal skeleton. What about plants? Different requirement, different solution. Wood. Cellulose fibers bonded with lignin. Again, can be extremely strong. Now we have artificial glues to match lignin, we can re-form wood into "glulam" beams, which are pretty much the equal of structural steel. Interestingly heartwood is not living tissue. A tree protects it from external attack with a skin of living tissue, but in most mature trees it is rotting in the centre. Which does not matter to the tree, or which may even be of benefit. A cylinder is as strong as a solid trunk. As the core of the trunk rots, nutrients that were locked up in the heartwood are released back to the tree's roots. Droppings from creatures that take up residence in the trunk provide more nutrition. Eventually of course rot gets the upper hand and the tree dies if it cannot regrow from its roots. Death is part of nature's plan. Insect exoskeletons and fungi use chitin, yet another remarkable biological material, though one better suited to small elastic structures than large ones. In short, I think it likely that the materials evolved for skeletons cannot be bettered by purely biocompatible processes. [Answer] I think the material matters less than the process by which it is assembled. The concept of a growing creature implies that this thing is able to absorb "fuel" of some sort, and slowly add it to various regions of itself, in a certain configuration and format. I would argue that nothing short of nano-technology can accomplish this. And if we're dealing with nano-tech, then they might arguably be able to tear the "fuel" apart at the molecular level, and glue the needed material to its bones atom by atom. At that point the bones could be made out of practically anything. [Answer] Carbon nano-tubes. Satisfies Case 1 by nature of this being a carbon based planet. As a result, there would be some level of carbon available to be synthesized into replacement 'bone' material (given that the species bodies are adapted to undergo such synthesis). Satisfies Case 2 somewhat because (if I'm understanding correctly) carbon nano-tube 'bones' could be replicated on a case by case basis, bespoke to the individual. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. The coldest place in the universe that we have observed is in the [Boomerang Nebula](https://en.wikipedia.org/wiki/Boomerang_Nebula). Similarly to a refrigerator, heat is carried away through a fluid, resulting in a space colder than the surrounding environment. However, in the case of the Boomerang Nebula, the coolant is heated gas being expelled away from the remains of a star - bringing almost all heat energy with it. This seems like an efficient way of removing heat / cooling a large object - and perhaps it could be applied to a planet rather than a star (or a fridge). For instance, a planet with a [runaway greenhouse effect](https://en.wikipedia.org/wiki/Runaway_greenhouse_effect) may channel its heat outward relatively quickly, a planet too small to hold an atmosphere may lose gas quickly, or a planet without a protective magnetic field may be stripped by solar winds. --- So about how cold can a planet actually be? * Any feasible, naturally occuring method of cooling is acceptable; if it is speculative, it must be justified. * The accepted answer will be credible and justify a reasonable surface temperature colder than those provided in other answers. * Note that this is [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") so rather than "it could be around x degrees because this cold nebula works in the same way" you must provide calculations or citations. * The rest is up to you. I have no specifications for this planet other than that it must be colder than the temperatures the [cosmic microwave background](https://en.wikipedia.org/wiki/Cosmic_microwave_background) usually permits; you can choose size, density, composition, location, nearby objects, moons or lack thereof, etc. [Answer] 2.7 Kelvin is the lowest stable temperature The lowest physically possible temperature is zero Kelvin, equal to -273.15 degrees Celsius or -459.67 degrees Fahrenheit. The microwave background radiation left over from the big bang is at 2.7 Kelvin, so anything just floating about far from any star will at least be warmed to this temperature. Any further cooling, such as gas expansion, evaporative cooling etc, sounds like it would "run out of fuel" fairly quickly on a planetary and geological scale. You may however consider the Chem SE question [Chemical reactions with a room-scale cooling effect](https://chemistry.stackexchange.com/questions/1238/chemical-reactions-with-a-room-scale-cooling-effect) for endothermic reactions. The surface of Pluto can get as cold as 33 Kelvin, so we find the really low temperatures even in our cosmic backyard. 10-20 Kelvin is meanwhile a typical low temperature for interstellar gas and dust within our galaxy. Story-wise in hard scifi, why would we care about the exact temperature? Well, superconductivity may feature in the plot and it turns out that all elements that can become superconducting on their own, become so [below 10 Kelvin](https://en.wikipedia.org/wiki/List_of_superconductors). Mercury for instance, goes superconducting around 4 Kelvin. Many elements such as Aluminium, even need to go below the cosmic background temperature. However, today we know of many compounds that are superconducting until well above the temperatures of Pluto. (Pluto is reported to have a max temperature of 55 Kelvin) ]
[Question] [ There is a nocturnal mammal, about [the size of a common red fox](https://en.wikipedia.org/wiki/Red_fox#Dimensions), which has evolved (by way of some unspecified-at-this-point selective pressure) the ability to see well in situations involving large contrasts. More specifically, an ability to make out details in areas with large differences in luminosity subtending very small angles as seen from the creature's point of view. Something like: If you point a flashlight at it at night, it is able to make out not just the lamp in the flashlight, but also your fingers grasping the flashlight, from some non-negligible distance. Two questions: * What adaptations to the creature's eyes (and more generally its [visual system](https://en.wikipedia.org/wiki/Visual_system)) would allow such vision? * What other effects on the creature's eyesight might (would) those adaptations have? [Answer] We already have this. The human eye can see some mighty wide dynamic ranges. That's why scenes can look beautiful, but when we snap a picture, we find the picture is heavily saturated. The [dynamic range](http://www.cambridgeincolour.com/tutorials/cameras-vs-human-eye.htm#sensitivity) of the human eye is about 10-14 fstops, or a ratio of about 1,000,000:1. The equivalent level of sensitivity for touch would be being able to lift a car, and then be aware of a feather dropping on top of it! General purpose dynamic range is very difficult to attain, because you need a very sensitive sensor and a very wide bandwidth channel for the data. Typically animals adapt to the sorts of high dynamic range scenes they expect to need to operate in. One major example of this is the need to be able to see a bright sunlit field and yet still see things resting in the shadows. To support this, human eyes (and all eyes that I am aware of) have a highpass filter built into the retina. As a photo receptor is hit by light, it inhibits nearby receptors so our retina really shows the difference in light across the scene. The brain then stitches this together. You can see this effect by staring directly at a point without letting your eye move. Eventually your entire vision will turn grey as your brain loses track of the overall lightness of the image. In fact, your eyes undergo a small jitter on a regular basis, simply to refresh the image that you were staring at! Eyes are marvelous things. Another approach would be occlusion. This is actually used on some of our telescopes to blot out a bright star to explore for dim stars or exoplanets around it. In this case, the telescope designers knew that there would generally be one circular bright object and a bunch of dim stuff around it, so they put a physical barrier to occlude the bright star's light from reaching the sensor. You could do similar if our optic nerve had a reverse path back to the retina that we could use. Your brain could "paint" an occlusion by sending signals to parts of the retina to attenuate themselves. Of course, this would only work in scenes where the brain could accurately predict which areas of the retina needed occluding, but it wouldn't be hard to develop a scenario where your flashlight holding example was realistic. [Answer] Our eyes have a dynamic gain, taking several minutes to adjust. So, the bright light will overblow the night vision and reset the range to spoil the night vision. An adaptation to allow simultanious vision at different brightness levels would be to have different pixels perminantly set for different levels, and the dark-range pixels are not hurt by over exposure. We already have separate rods and cones, and the rods are ignored when they go beyond their brightest possible setting. So it would be a refinement of this system to have the rods stay in a darker setting only, and cones adjust to brightest elements being viewed. Having two different input channels perceived as different would add visual contrast, in the same manner as being different colors: the “rod colored” fingers would be seen clearly against the bright (normal color) light, with only bloom to prevent seeing the edge of the fingers (one pixel width) immediatly adjecent to the light. You were specifically asking about an adaptation to the real mammalian eye. Further separating rods and cones seems to be the way to go forward with what we have already. If you wanted to design an optical instrument from scratch, there is a wider range of possibilities. ]
[Question] [ Not to say it can be fired without a tripod and/or a mount to disperse the recoil, but could railgun artillery or anti-tank rifles work in a near future setting with miniaturized fusion reactors? I'd imagine there would be a battery with enough juice for one shot built into the actual weapon and the soldier could also carry a larger battery pack to power additional shots. Would this be plausible? [Answer] Recoiless rifles like the Carl Gustav balance the recoil force of the projectile by allowing 4/5 of the propellant gas to exit the venturi in the rear. For man portable weapons like the Carl Gustav or various Soviet era 80-90mm recoiless rifles, this produces a pretty impressive backblast, which limits where the soldiers can fire from (allowing the sudden rush of gas into an enclosed room or reflecting the backblast off a nearby wall has some pretty obvious issues for the soldier). [![enter image description here](https://i.stack.imgur.com/ZBcwg.jpg)](https://i.stack.imgur.com/ZBcwg.jpg) Carl Gustav firing However, this suggests a way to get a man portable railgun without the extra mass and expense of a fusion reactor. The round is contained in a recoiless casing like a Carl Gustav, but the 4/5 of the propellant isn't only countering the recoil force of the round moving down the barrel, but also powering a MHD generator built into the venturi. [![enter image description here](https://i.stack.imgur.com/eATQY.png)](https://i.stack.imgur.com/eATQY.png) MHD generator as it might appear in a venturi The round is loaded and the venturi/generator is locked in place. The firing of the round accelerates the projectile into the rails while the backblast powers the MHD generator, which energizes the rails and takes the moving round from a few hundred meters/second to thousands of meters/second in a fraction of a second. [Answer] # No, because of recoil When they tried putting a 120mm smooth bore on a [CV 90](https://en.wikipedia.org/wiki/Combat_Vehicle_90), they found that the recoil bent and twisted the chassis out of shape. The forces were such that a tracked armored fighting vehicle could not stand up to it. A 120mm sabot shot has a muzzle energy of about 5 to 7 MJ. You want to have something that... * Is man portable that is to say: much smaller and flimsier than a vehicle * Fires a projectile at up to 4 times the muzzle energy, which results in the equivalent increase in recoil forces * Has a much shorter barrel, which means it needs to accelerate the projectile to muzzle velocity much quicker, which means even higher recoil forces So in short: no, this is not plausible. A "tripod, or mount" cannot handle those forces. The kind of "tripod, or mount" that you need to hold up to these forces need to look something like this: [![enter image description here](https://i.stack.imgur.com/h1XTk.jpg)](https://i.stack.imgur.com/h1XTk.jpg) [Answer] ## Plausible? Short Answer: Yes-ish. Back of envelope maths, assuming your lower-bound on energy and a $1kg$ mass: $$ E\_k = 1/2 m v^2 $$ $$ 5\times10^6 = 1/2\times 1\times v^2 $$ Moving all the known numbers over to one side, and doing the maths. $$ v^2 = 10,000,000$$ $$ \therefore v = 3,162 m/s $$ Which is like nine times the speed of sound. Some more back of envelope maths, based on the [numbers Wikipedia gives for the Carl Gustav's projectile weight and velocity](https://en.wikipedia.org/wiki/Carl_Gustaf_recoilless_rifle#Ammunition): $$ E\_k = 1/2 \times m \times v^2 = 1/2 \times 3.1kg \times (255m/s)^2 $$ $$ E\_k = 0.2 MJ$$ That's a $25\times$ increase in kinetic energy. Which is a lot, but makes sense because the hurty-part of the Carl Gustav is the explosion. A railgun's hurty-part comes from the impact. You can trade increasing projectile weight for decreasing velocity at the cost increasing recoil, but heavier projectiles are less likely to glance off if they impact at an angle. [Answer] Certainly! Currently the limiting factor on a man portable rail-gun is several things, first and foremost providing enough energy to fire one. Conventional ordnance stores the energy in chemical form, which is energy dense ([4.6MJ/Kg for TNT](https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table)) whereas the batteries required for an electrical rail-gun are far less effective (at most [0.46-0.72MJ/Kg](https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table)). Assuming a ten fold increase in battery capacity, rail-guns would be very competitive. Having a portable energy source such as miniature fusion reactor would be much harder to develop, but this would allow much higher energy densities ([576TJ/Kg for Deuterium-Tritium](https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table), ignoring the weight of the reactor). Rail-guns also suffer from rapid wear caused by the severe friction during firing. This would either require more resistant conductive materials, or more frequent barrel changes than conventional ordnance (but not a huge challenge). As for effectiveness, we can compare (as another question did) to the [Carl Gustaf](https://en.wikipedia.org/wiki/Carl_Gustaf_recoilless_rifle#Ammunition). If we assume all of it's ~4kg projectile is TNT or equivalent, it would have an explosive force of ~18.4MJ (and we can assume kinetic energy is minimal). This compares very favourably to 20MJ in your specification for the rail-gun. In short, with improvements in battery or other portable electrical supplies, a rail-gun is a very feasible option. ]
[Question] [ Quadcopters are cool, I don't think anyone can refute this. While Drones use a simplistic boring version of their design, these versions are often used in science fiction, but is this powerful, flying vehicle feasible? [![enter image description here](https://i.stack.imgur.com/tpePt.png)](https://i.stack.imgur.com/tpePt.png) Is the Quadcopter realistic? If not, what do I have to do to make it feasible? Why would a military use it over its counterparts? [Answer] The scale of the model in your image is not very realistic. At that size, it is more efficient to have two rotors, like the V-22 Osprey. In order for four rotors to be feasible, you would need a much larger body of aircraft, so that the four rotors are required for stabilization. I am not an aeronatical engineer, but I suspect that the reason drones use quad rotors is that they are more concerned with stability and ease of piloting than efficient weight:thrust ratios. A heavy cargo plane with four rotors would be pretty cool, if there was a sensible in-universe justification for wanting a VTO/L version of the C-5 Galaxy. [Answer] # No, because direct lift is expensive, and the [square-cube law](https://en.wikipedia.org/wiki/Square-cube_law) First, direct lift — i.e. your engines providing an upwards pointing force directly — is always "expensive" in that it requires lots of fuel / engine power to achieve. Indirect lift, by for instance using airfoils / wings, is much cheaper and efficient. The "only" drawback of indirect lift is that you need an extended strip of suitable land as a runway. Second, the [square-cube law](https://en.wikipedia.org/wiki/Square-cube_law) means that small quad-copters do not translate to big dittos. Generally speaking the square-cube law means that if you increase something in size — i.e. scale up or down width, height and depth by the same ratio — then all of the surface areas increase by the square of the change, but the volume and therefore the weight increase by the cube. So if you double something in size (multiply by 2) , all of the surface areas increase by a factor of 2 squared, i.e. $2 \cdot 2 =4$, but its weight will increase by 2 cubed, which is to say $2\cdot2\cdot2=8 $. This is a problem for rotor-craft because the direct lifting force that a rotor-craft needs in order to take off and land is roughly proportional to the surface area of the [rotor disk](https://en.wikipedia.org/wiki/Helicopter_rotor). But the surface area only increases by the scale squared while the weight, and with that the gravitational force that you need to overcome, increases by the scale cubed. So even if a small quad-copter can take off with ease, a large one will be under-powered. Vertical Take-Off and Landing has been sought after eagerly ever since World War II showed that the things that you call "airfields", your enemy calls "huge, immobile targets"; they are bomb-magnets. And yes, the helicopter can achieve VTOL, hooray! But the helicopter generally lacks in all the other areas that fixed-wing aircraft do well: speed, cargo capacity, endurance. Unfortunately this translates to quads-copters as well. And it does not become any better when noticing that the quad needs all rotors to spin and to spin in sync in order to stay afloat and not [fall over in a spectacularly violent fashion](https://www.youtube.com/watch?v=n3lbKqStvHI). [Answer] The main problem is that lift is proportional to the area swept by the rotors. This makes most quad copter configurations less powerful than a helicopter of the same size. In your picture you will see a large gap between the rotors over the center of the craft. If you had a single much larger rotor then you could generate more lift. One way of doing this is [triquad](http://diydrones.com/profiles/blogs/researchers-say-triquad-is-more-efficient-than-a-quad) design which gives you the large rotor area but simple rotor motors of a quad copter. [Answer] There are two main problems with the image you posted, one the "wings" does not tilt. that would remove 1/5th of the thrust you need. If the wings were tilted you don't have that blocking force. The second is the reaction time of an engine is too slow, the computer controlling the stability runs about 1000 calculations per second and a lot of "smaller model" drones running engines instead of motors have big problems in that particular area. Switching from engines to motors would solve that problem. As for performance, by making a quad copter with [variable pitch blades](https://en.wikipedia.org/wiki/Variable-pitch_propeller) such as helicopter and planes would greatly increase performance but this is a huge challenge on models in the 250-500mm size. About the propeller size it has greatly to do with the motor RPM and the propeller pitch. Contrary to what Steve mentions in the comments, the propellers might not be too small, small propellers increases the agility and acceleration but at the cost of fuel consumption, where larger propellers (depending on pitch) increases the flight time and or top speed. (Imagine smaller or larger wheels on a car) ]
[Question] [ Assume the planet's orbit around Sirius B is much closer to its parent star than we are to the sun so it still receives enough light and heat to form an Earth-like environment. What does night look like on this hypothetical planet? Would Sirius A shine brightly in the night sky like a full moon? Would there even be a night the way we think of it if Sirius A in the sky? If you were to lie back on the alien grass at night on the top of a tall hill, what would you see? [Answer] Sirius B has an eccentric orbit around A, at its closest it is about 8AU from A; at its most distant, it is 31AU. It takes about 50 years to complete an orbit. When close to Sirius A, the main star would be as bright as the sun is on Earth (mag -27). When at its most distant, the Sirius A would have a magnitude of -25: Still too bright to look at, Far brighter than the moon. If the star was above the horizon it would be "day". Sirius B is much less bright. From any reasonable orbit, it would appear as an intensely blue-white point of light. The eccentric orbit is going to play havoc with the climate. There would be a 6 year "summer" as you pass close to Sirius A. 10 years of cooling, and then a long winter lasting over 20 years, before slowly warming again. edited In the absence of Sirius A, and using a procedure to [calculate the habitable zone](http://www.planetarybiology.com/calculating_habitable_zone.html) puts a planet in the goldilocks zone of Sirius B at about 0.09 AU from the white dwarf. But since this planet is also going to be significantly heated by A, you should probably double that: about 0.2 AU. That is closer than Earth is to Venus, but barely enough to show a significant disc. Now this planet has been through a lot. It's host star used to be a bright white star, somewhat more powerful than Sirius A is now. This star has passed through a red giant stage, then has disintegrated as a stellar remnant nebula, losing most of its mass. During the red giant stage, the planet would have been thoroughly baked. To have survived the red giant phase it would have had to have been a long way from the star (So far that it's hard to place it in an orbit that is stable) And then somehow migrated to 0.2 AU. [Answer] Go there in the [Celestia](https://en.wikipedia.org/wiki/Celestia) program, and look around. [![Noon,no air](https://i.stack.imgur.com/yxZnT.jpg)](https://i.stack.imgur.com/yxZnT.jpg) > > Celestia is a 3D astronomy program created by Chris Laurel. The program is based on the Hipparcos Catalogue (HIP) and allows users to travel through an extensive universe, modeled after reality, at any speed, in any direction, and at any time in history. Celestia displays and interacts with objects ranging in scale from small spacecraft to entire galaxies in three dimensions using OpenGL, from perspectives which would not be possible from a classic planetarium or other ground-based display. > > > The map it uses for this ([HIP](https://en.wikipedia.org/wiki/Hipparcos)) is a high-precision catalogue of more than 118,200 stars. Since you are looking from a point nearby us, as such things go, I think it will be more than enough for naked-eye constellations. If Celestia doesn’t have a planet around Sirius B in its database (since it’s not a known exoplanet) and you can’t find it in an extension and don’t care to add it yourself, just plug in a location for your POV that’s the same distance from the star that you have in mind. The picture below is what the sky looks like from a point near Sirius B, looking at midnight up towards Sirius A. (View full image at 100% to see the stars clearly. Well not clearly; the jpeg doesn’t do it justice! Use the program directly if you want to compare the constellations to the familiar ones. You can adjust the visible brightness within the program, too.) [![View of A from near B](https://i.stack.imgur.com/12YtV.jpg)](https://i.stack.imgur.com/12YtV.jpg) You can adjust the angle of view to show what you would see looking up from the hill at night, or what the suns look like in the day. The overlay shows that at this distance the [apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude#Table_of_notable_celestial_objects) is about −22.6, making it much brighter than the moon but not as bright as the sun. It has 1/40 the light that the sun does on Earth, or (more familiar to me) about 5 photographic stops. So it will be what we consider to be well-lit for indoors. (Anybody have a more direct reference to relate the brightness?) ]
[Question] [ In this Earth-like world, governments of several countries have decided to allow tourists to visit most of their secret research facilities in a similar way to what happened in [Jurassic Park](https://en.wikipedia.org/wiki/Jurassic_Park_(film)). This time the visitors will not have the chance to be eaten by researched subjects. They will have guided tours through the laboratories (no touch and no interference policy strictly enforced by [transparisteel](http://starwars.wikia.com/wiki/Transparisteel/Legends)) and they will be able to watch live demonstrations of the technologies being developed. A few main reasons for the governments' decision were: 1. direct funding from tourism; 2. increase awareness of technological advancements with the ultimate goal of allowing joint researches with public institutes; 3. increase researchers and possible test subjects recruitment; 4. allow the general public and military to (re)gain confidence in the governments that manage these research facilities. A few options have already been considered for the opening process: * send a few familiar/knowledgeable persons first and get their feedback (a.k.a. Jurassic Park style); * open them only to graduated scientific researchers; * entrance will only be given to those who scored over 70% on a specific psychological test. Even with precautions like these, how could the related governments manage most of the direct and indirect consequences of opening these facilities to public? ## TL;DR What would be the most effective approach of launching these research facilities as tourists attractions and their consequences? ## Update (2016-09-09) I am revamping the question due to some points that may not have been sufficiently cleared out: * I used the sci-fi word [transparisteel](http://starwars.wikia.com/wiki/Transparisteel/Legends) since I am not familiar of one-sided transparent metals capable of blocking explosions and various kinds of waves and radiation (as a sci-fi space-ship supposedly does). * Any visitor would need to sign an agreement which discloses that the tour guide management or the facility itself will not be held liable in case of death or injury inside the facility (if anyone manages to blow up something, it's not the management's fault). * Most researchers will not be aware of visitors passing by through the tunnels. * The tunnels will only pass through non-critical research operations rooms. * The way the research is shown to the visitor does not provide a chance of the research itself to be copied or reverse-engineered or to identify the researchers working on them (e.g. this transparisteel manages to blur out anything that may identify someone, similarly to Google Maps face blur). * Visitors will not be able to leave the tour tunnels (there is literally no access to the facility rooms, even to tour guides). * Different tours will require different sets of access permissions from the visitor which may depend on, for example, psychological test results, education level or simple monetary contributions (expensive tickets). * The rooms will present things that have never been seen before by the public (if you are having a hard time figuring out what is going to be shown, you can think of a live presentation of Nikolas Tesla's unknown technology). * Some of the rooms may display actors testing and presenting a relatively safe technology (or open rooms outside the facility may be created in order to perform shows where safe, known but rare technology is demonstrated to an audience). [Answer] I think the only option is to open a science museum adjacent to the actual research facilities. It is staffed by actors playing scientists, or perhaps by second-rate scientists used as actors. ## Real Science vs. Hollywood Science A lot of tourists would be disappointed at what they see. There are a hundreds of failures for every spectacular success. And even a successful experiment might look like a failure because it is only designed to test a specific aspect of new technology. Or there is nothing to see except for tiny wiggles on a chart. ## Unwanted Publicity There will be foreign spies among the tourists. What will they learn from what they see? Among other things they will learn who your top researchers are and what they do. Spies could then try to befriend the researchers in the hope of learning details. If the researches are told to be too wary about such things, the public relations effort might backfire. ## Unwanted Distractions Will the researchers be as productive as they are now when a new tour group gawks through the window every hour? What happens if a tour group passes by and the research team has a break with coffee and donuts. The tourists would be disappointed. So the project management will pressure the researchers to schedule their breaks according to the tour schedule, not at the best time for productivity. ## No Haystack to Hide Needles Imagine they have some research projects that really have to stay secret. Enemy agents would have to take note which buildings don't offer tours, and keep track who goes in and out. [Answer] If the General population is allowed and also earth-like, be prepared to execute damage control due to well-meaning but inadequately educated or informed citizens with anti-research based fears. This may be costly and reduce/eliminate the tourism benefit. If any of the research subjects involve living beings, consider the subjects themselves reacting negatively to being treated as tourist attractions. Be aware of the condition that the result of any experiment is affected by the observers, whether the observer is the research staff or the tourist. ]
[Question] [ I am looking at the feasibility of a potions factory system. Perhaps one that focuses solely on healing potions. They need to be available and relatively easy to get. Given a world where magic is rare or moderately rare, how can this work logically? Value of the potion would be high for a commoner, but not difficult for most adventurers. (Basically the equivalent of 50 gold, in D&D terms). I've been thinking about also having weaker potions out there that heal less than the standard for a cheaper price. There will be more casters in the geographic area where the potions are being made, but I don't want to count on casters randomly coming in and helping out. The only thing I can think of is a magical "blue print" made by a magic user which can then by used by non-magic users a limited amount of times. EDIT CLARIFICATION: Alchemy is involved, but it is essentially a liquid version of a spell, so magical energy needs to be part of the process. The stuff closes wounds instantly, and heals them. Ingredients/ingredient rareness I can worry about separately, I am just looking for the answer to industrializing when the magic to make it is rare. [Answer] Why is magic rare? Is it because it's very difficult to learn so there aren't many mages? Or is it taboo/outlawed/not believed in/with a sort of masquerade? Or is it that there's just not much "magical energy" in the world. If the third one, then the easiest explanation could be that healing magic is exceptionally efficient in terms of magical energy usage, or that the Gods approve of healing and therefore will make healing potion factories an exception to whatever the limiting factor is. If either of the first two, we can say that there aren't many mages around and so you probably won't find many who are willing to sit casting the same spell at a potion assembly line all day when they could be out unlocking the mysteries of the cosmos. But it strikes me that a magic potion requires a mundane component (ingredients, the mixing process, etc.) and a magical almost Eucharistic process. The first part is easy to mass-produce - farms, mines, pipes/vats/tubes and furnaces should sort it out. But depending on how magic works in your world, the second part could be achieved by a wizard creating a magical device which channels the magical energy in massive quantities at the vats of the mundane soup in the same way that a single mage would at a single vial. Now the thing is, creating such a device takes an extreme genius level mage and as we know there aren't many mages, never mind mages powerful enough to do something like this - in fact there's only one, and luckily s/he happens to like healing - which is why you don't see all sorts of potion factories popping up around the place - just healing ones. [Answer] Break the process down into steps from the moment the ingredients enter your factory. Now group the common steps together; for example, 10 potions need finely chopped sage and no magical input, so you have one lot of people just chopping sage and another group delivering those to the different processes. Identify the stages at which a mage must provide input. Again group those together, if possible. If not, set up a schedule for a mage you hire, as in, he'll show up in the morning, or at midnight or at the crack of dawn or whatever the requirements are for potionmaking and first cast his spell on potion process A, then C, then B, as needed. Trial and error till you get the most efficient configuration. If the magic can be preserved through alchemy, then it's just another ingredient in your assembly line. Just hire mages to produce them at a given rate, e.g., 20 spells a day at 15 gold. The rest is simple, you've got an optimised assembly line, so go for bulk. Start with a dozen small cauldrons. Once your people are reasonably competent enough to not waste ingredients, switch to large cauldrons, then set up an experimental giant crucible. Once the crucible is fuctional, set up conveyor belts (pedal or mill powered) to feed a hopper and a pipeline to carry away the final product to a bottling plant. Put mages to work to find a way to convert the batch processes to continuous processes wherever possible [Answer] You would need at least 1 maybe 2 or 3 Mages to do to work the actual spells but that mixing and putting together of ingredients could be complete done by humans or machines or both. What you could have is humans or machines Gathering ingredients mixing ingredients in a gigantic pot or mixer, the Mage shows up every once in awhile to do a spell over the ingredients, then the humans or machines take the new inspelled liquid and divide them up into hundreds of small bottles. And then there you have it hundreds of potions created in a single day and ready to be sold. [Answer] X = How many potions can your average alchemist make per working day? Assuming your alchemists work five days a week and get six weeks off per year that’s 46 weeks multiplied by 5 so 230 working days per year and X230 is your rate of production, per alchemist, per year. Now how many alchemists are there for every 100 people and approximately how many potions will these 100 people need on a yearly basis? I think this is what you’re really asking about, you want to know how much a potion should cost for a given degree of availability, a good measure of that is to compare supply and demand. If supplies are plentiful the cost will go down and people will use health potions for increasingly trivial wounds, maybe even as a pick-me-up after a hard day farming, whereas if availability is restricted they might be expensive or not even for sale to the general public. ]
[Question] [ Would it be possible for a planet to have an ecosystem where life lives without ever touching the ground? By this, I mean that the producers (whether by photosynthesis, chemosynthesis, or other methods) float (or fly, etc.) above the ground, with the consumers also doing this, with none of those ever touching the ground (except, maybe, if they die). Note that, if needed, I would be fine with very different conditions from the Earth. If this is possible, how could it work and could the world be survivable to humans? EDIT: I only care about an ecosystem that never touches the ground. I don't need there to be no other life on the ground. [Answer] If you're okay with something extruding from the ground, rainforest canopy ecosystems have little contact with the ground, but still require the trees to bring nutrition up to the canopy. The main issue with nothing touching the ground is that there is no way for dead stuff to come back up, so you end up with a big pile of compost on the ground and some basic organisms that can sustain themselves on aeroculture alone. A less survivable environment for humans, and probably not very friendly for human life, are atmospheres with thick clouds. Maybe there's no ground at all. You should take a look at hypothetical life on [Venus](https://en.wikipedia.org/wiki/Life_on_Venus) or gas giants. Take away the noxious fumes and the heat and you may have something livable for complex organisms. [Answer] Define ground. Ground The solid surface of the earth Ok then. Just put it on a different planet. But on all seriousness, put your ecosystem in the ocean, or on a gas giant. \Ocean Phytoplankton get sunlight, fish get phytoplankton, and sharks get fish. \Gas Giant The gas giant has strong thermals. Plants float on the thermals. The plants receive sunlight from the sun and minerals from the gas(?). Bugs eat the plants. Birds live in the plants, eat the bugs in the plants, eat the plants, and get eaten by bigger birds. [Answer] Larry Niven's [Smoke Ring](http://rads.stackoverflow.com/amzn/click/0345460367) series had an ecosystem, complete with photosynthesizers and heterotrophs, that had no ground that any of them could possibly touch. The atmosphere was a torus in orbit about a neutron star. Kirkus' [review](https://www.kirkusreviews.com/book-reviews/larry-niven-4/the-integral-trees/) of The Integral Trees summarizes the concept. The world was more-or-less successfully colonized by humans. [Answer] For your entire ecosystem to float in the air, you obviously need a mechanism that keeps all the necessary components up there. Since the complex molecules that make up life are more dense than the gases making up "air" and most biological processes need liquid water which also is a lot more dense, those components tend to fall down to the ground or wherever gravity pulls them. The most plausible way for living beings bigger than a cell to maintain buoyancy would be to feature blisters or balloons of Hydrogen. Helium is unlikely to work since it's inert and would need to be captured directly from the surrounding air. If there is enough Helium in the air mix to capture it easily, it's buoyant effect will be much smaller. Hydrogen can be extracted from water present in a much denser air with electrolysis or some other fairly simply chemical process. So, anything living can stay afloat, but if it's damaged or dead, it will fall down. New generations would hitch a ride on the parent until they achieve their own buoyancy, so that is not an issue. The major problem to solve is how to get back all of the heavy molecules that fall down, out of the ecosystem. There are two sources of heavy molecules that I can see: 1. Storms/tornadoes picking up (organic) muck from the ground and spreading it into the floating ecosystem. where it's captured by large floating mats or webs that serve as a feeding ground for more complex life forms. This has the advantage of potentially cycling forever. 2. Heavy molecules rain down from space. The planet/moon/ecosystem is moving through a very large cloud containing heavy molecules that somehow was blown off of a planet or escaped becoming part of a planet during the solar system's formation. This scenario would allow for a better dispersion of the molecules, but would only last as long as the cloud does, which would likely be shorter than it takes for life to evolve (balloons). Humans would have a very hard time surviving in this ecosystem (without their own balloons/flying devices). The first problem is that humans are heavy, with a density like water, about a thousand times more than air. They'd be limited to the biggest floating structures and risk tearing right through any spot that's too thin. Still, it is possible for a [large enough bunch of balloons to support humans](https://www.youtube.com/watch?v=eUhY2kzlAFQ). The second problem is that humans need lots of water and food to power their metabolism and especially brains, while the entire ecosystem needs to make do with very little of either. Water would be available in small quantities from rain or clouds, but since collecting a pool of water would force a floating lifeform to sink, there are not likely to be any pools available. Food may or may not be a problem, depending on how edible the bigger floating lifeforms are for humans. But eating the float that keeps you up there is not a long term solution. Humans would be dependent on being able to reach different floats before their food and water run out, which pretty much requires some kind of flying device, unless the number of big floats is such that they keep bumping into each other. A more exotic way to support the flying ecosystem would be to have particles with some kind of anti-gravity effect. It might not be pure anti-gravity but some kind of magnetic interaction (like in the movie Avatar) that forces the particles or lumps of matter containing them to rise up from the ground. This would allow for heavier-than-air materials to get and stay up in the ecosystem and would generally make it more "normal", since you just insert the needed quantity of antigrav material into any object you want and it will stay afloat. You want an island with a lake and a castle? No problem. You want a floating mountain? Go ahead. [Answer] ## Yes and No While you could have a large proportion of your ecosystem entirely airbourne, it's not a full ecosystem, there's a chunk missing after death. It's said that [swifts won't land for the first two years of their lives](http://www.rspb.org.uk/makeahomeforwildlife/advice/expert/previous/swallowsinair.aspx), and the concept of a bird that never touches ground has been [discussed here before](https://worldbuilding.stackexchange.com/questions/11517/a-bird-that-never-touches-ground). Let's consider the other available 3 dimensional ecosystem, the ocean. Based on plankton rather than plants, it should be possible to make something equivalent airbourne. It turns out you don't need to do too much work as the insects already fill this space ([Bumblebees have been found at 18,000ft on Everest](http://www.independent.co.uk/news/science/bumblebees-set-new-insect-record-for-high-altitude-flying-837834.html)), you just need to create an airbourne photosynthesiser in the same style as phytoplankton. Match these with the insect eating swifts and what you need next is a predator that can eat on the wing. This is harder, Harris Hawks can catch food in the air but usually they land to eat, [however a bald eagle has been caught on camera eating in flight](http://www.featheredphotography.com/blog/2011/02/08/bald-eagle-eating-a-fish-in-mid-air/). That's all the eating and sleeping dealt with, but reproduction on the wing is an entirely different game. Airbourne humans will need to use lighter-than-air flight rather than aerodynamic flight as the latter would be too power intensive. This creates airbourne platforms and takes a lot of the fun out of getting high altitude photosynthesis, so you'd have to consider whether this ecosystem was actually dependent on humans or already evolved when they got there. It would also be hard to get large plants for wood, or metals for any heavy industry or manufacturing to high altitude, so consider what their airships are made of if landing for raw materials and manufacturing is not possible for any reason. [![Bald eagle eating in flight](https://i.stack.imgur.com/SWerV.jpg)](https://i.stack.imgur.com/SWerV.jpg) [Answer] Jasper mentioned the Smoke Ring books by Larry Niven which does indeed present an ecosystem with no real ground. The other option, also from Larry Niven, that could include an ecosystem that really never touched down would be the Megasphere from [Bigger than Worlds](https://en.wikipedia.org/wiki/Bigger_Than_Worlds) with the core of a galaxy on the inside and a breathable atmosphere light-years deep supporting a micro-gravity biosphere on the outside the ecosystem would be entirely composed of fliers of one type or another, you could fly to the moon on gossamer wings or take a chariot pulled by swans if you didn't want the workout. ]
[Question] [ This question already has answers here: [How large does a spacecraft need to be to be visible from the surface of the Earth at 400 km altitude?](/questions/3768/how-large-does-a-spacecraft-need-to-be-to-be-visible-from-the-surface-of-the-ear) (2 answers) Closed 7 years ago. The International Space Station is roughly the size of a football field and can be seen with the naked eye from Earth, usually as a tiny dot in the sky. In the setting I'm working on, there is an O'Neil Cylinder style space city (well, it is really more like a stack of Stanford Torus Rings, but never mind) in a similar orbit as the ISS that is just over six kilometres long and one kilometre wide. How would something of that size appear from the ground? [Answer] ISS is an only just visible dot of 100 meters in size which at 400 km height covers a one arc-minute angle. Your big space station would appear as a cylinder 60 times the length and 10 times the width of ISS, so it would be 60 by 10 arc-minutes (60'x 10'). And will be highly visible at the times it catches sunlight against a darkening sky. To compare, the moon is about 30' across. Your construct probably rates a nick. Space cigar? References: <https://en.wikipedia.org/wiki/Angular_diameter> <https://www.quora.com/Are-the-satellites-visible-from-Earth-by-the-naked-eye> <https://www.quora.com/How-large-would-a-satellite-in-Earths-orbit-need-to-be-for-the-shape-to-be-visible-and-identifiable-with-the-naked-eye-from-the-ground> In hindsight I kind of covered @JDługosz's suggestion. Hope it helps. [Answer] This is more of a comment, but because of the length I'm putting it here. While the size of the space station determines the angular distance that it occupies in the sky, the main reason that it would be visible at all has to do with the reflective surfaces which might be attached to it. The ISS is quite visible to ground viewers becsue the sun reflects off the vast sail like solar panels which provide power to the station.[![ISS STS-124](https://i.stack.imgur.com/2ybCC.jpg)](https://i.stack.imgur.com/2ybCC.jpg) A large space colony will have a lot more reflecting surfaces either as solar panels, or as mirrors to bounce sunlight into the colony. A Stanford Torus (or a series of torii as you propose) is generally marked by a large "top hat" mirror reflecting sunlight into the central axis, where it is further reflected by mirrors into the colony itself (through a giant slot cut into the radiation shielding facing into the axis) [![Stanford Torus](https://i.stack.imgur.com/XQ1uL.jpg)](https://i.stack.imgur.com/XQ1uL.jpg) Since the mirror itself is the diameter of the torus (one kilometre in your case), it will certainly be highly visible, and the one thing which attracts attention long before the actual station itself. Under some circumstances, the glare from the mirror might actually obscure the colony itself from viewers on Earth, so ground observers will see an extremely bright "star" passing overhead, rather than the colony itself. [Answer] At the distance a 6 km space station would not be much more vissible to us than the ISS, it would still just be a spec in the sky. Possibly a clike a grain of rice, but still, not very noticible. I gathered this from using google earth and looking at a distance of 6 km from the height of ISS. A larger station might also be positioned further out than the iss for various reasons. Which again would make it appear smaller. ]
[Question] [ There are many kinds of body modification such as [Tattoos](https://en.wikipedia.org/wiki/Tattoo), [Piercings](https://en.wikipedia.org/wiki/Body_piercing) and [scars](https://en.wikipedia.org/wiki/Scarification), but all of these use your skin to work. Many animals in nature though, like snakes, reptiles and spiders often shed their skin. As redoing all of your tattoos or paying to repeirce your new skin would be ridiculous, what forms of body modification would survive a good old shedding of the skin? [Answer] we shed our skin too, we do it bit by bit, reptiles do it in one shot, and other animals work in patches. The skin that is removed is just the very superficial layer [![enter image description here](https://i.stack.imgur.com/1MAhK.gif)](https://i.stack.imgur.com/1MAhK.gif) When we think about the "skin", the part you shed, we are basically talking that layer called Epidermis which is also composed by layers: underneath the shedding layer you have new skin cells and below that a layer you have the one where cells are active and will divide continuously to form new cells. [![enter image description here](https://i.stack.imgur.com/c0V1W.jpg)](https://i.stack.imgur.com/c0V1W.jpg) Now, a tattoo has to be deposited at a correct depth for maintenance of the color and appearance. This is the top third of the Dermis layer, in the area that is too deep to be pushed outside basically. With modern equipment the tattoo is deposited at a constant depth, the needle goes straight down and the delivery of the ink is very precise. In the homemade (think jail tats) or older tatoos that used less precise instruments the needle would be a bit all over the place, the depth of the ink at this point is variable and if some is more superficial and is in the basal layer of the epidermis it could be slowly (very slowly) slough off. That is one of the reasons a tattoo might look like "fading" or changing color. Obviously with the less precise method you can also have ink delivered way deeper that will stay even if you actively try to remove it (unless you go at it SonsofAnarchy style). If you compare an extreme shedding the skin to dermoabrasion you can see right away what could be the extent of "tattoo loss" you can obtain. Before laser dermoabrasion was a way to remove tattoos and some of them are simply too deep for that method. All the other kind of permanent body modifications are even deeper than the tattoos, that's why they are called permanent. So unless you envision a skin shedding to a depth that is rather extreme, the reality is that its unlikely you will loose all your tats. But its worldbuilding so you can give a little nudge to reality if you really need to. [Answer] Piercings. (Imagine picture of [Sir Hiss](https://en.wikipedia.org/wiki/Robin_Hood_(1973_film)#Cast) sporting a tongue stud. Caption: "like my pierssssssing?") [Answer] To name a few: skeletal/cranial modifications (for example, humans used neck rings and skull shape modifications), body shape modifications (tightlacing, lotus feet), various implants, haircuts and hair coloring. (You could also check [wiki list](https://en.wikipedia.org/wiki/Category:Body_modification) of modifications, most of them do not rely on skin). [Answer] Piercings, brands, and scars. piercings because well it doesnt really have to do with marking the skin as much, branding becasue it makes a permenant marker on your skin, even if a creature would shed, and scars if they are deep enough (and will be healed naturally eventually) [Answer] Both Percings and Scars (Depending how severe the scare is) would remain A percing would remain as it doesnt just affect your skin, it pierces your flesh so unless you regrow your muscles as well the hole for the percing will remain. Why the human body does stuff and the science terminology are a bit (a lot) beyond me so I have tried to dumb it down to my level so I can explain it A scar, unless it is just skin deep, would also remain as a [scar is](http://patch.com/iowa/ankeny/what-is-scar-tissue-and-how-does-it-affect-your-range-of-motion) soft tissue. The link explains it quite well that even I could understand most of it. A short version of what they link says is basically; When you recieve and injury (no matter how big or small) it damages the "collagen strands of the fascia" (From what I could gather these are the threads that make up soft tissue) that damaged part of the body will then bind closer parts of the soft tissue to reduce strain, after a resting period the scar tissue should heal but doesnt always. @Erik vanDoren Does a wonderful job of explaining how scaring works below in the comments. Also you will remove all moles with your skin and are likely to have new moles in different places I do not understand biology too well so take this witha pinch of salt ]
[Question] [ Scenario (pick one): * You accidentally travel through time * Your time machine runs out of fuel or breaks * Your time machine gets stolen * A vengeful wizard banishes you to another time/dimension * You accidentally travel to a parallel Earth * You intentionally travel to a parallel Earth and get stuck Let's say you end up stuck in a friendly medieval-tech-level community that is willing to let you stay and help get you on your feet. So even though you'll miss high-tech society, you're going to be able to survive. However, medieval-level communities don't know much about nutrition, vitamins, minerals, etc, and you'd rather not get [scurvy](https://en.wikipedia.org/wiki/Scurvy) or any other of the nasty diseases caused by nutrient deficiencies. As a bonus, helping your community to become healthier will improve your standing with them, which certainly wouldn't hurt. How would you go about making sure that you will be getting enough of all of the necessary nutrients? [Answer] You may be surprised to hear that you would have very little to do. Medieval diets were actually very healthy in terms of lots of veg, fruit, etc. The main problem was getting enough food, not the balance of food. For example see [this BBC article](http://news.bbc.co.uk/1/hi/health/7148534.stm). Scurvy was only an issue on long shipboard travel, and then only because of the fact that for example dried fruit still lost its vitamin C and Eskimos found one of the few meat diets that included vitamin C. These two factors combined to make it very hard to identify the cause. If you want to help people then the main low-tech improvements you can make is developing chimneys with a proper draw to get smoke out of homes, improved agriculture and irrigation to increase food yield, and hygiene to avoid spreading of disease. [Answer] There have been a number of answers and comments on doctors in the Middle Ages, so perhaps we should clarify a bit here. If you are physically injured, anything from a broken bone to a battlefield injury like a sword cut, you will probably be treated by a barber (the red and white striped pole actually symbolically hearkens back to that time). Barbers would perform what we would call first aid and surgery, and were actually pretty good at it. I recall a show where an English battlefield was excavated, and one of the soldier's skeletons had a massive axe or pole arm cut across the face. Closer examination showed that he didn't die of this injury, in fact the edges of the cut bone had healed over, so he obviously recovered enough to soldier on perhaps several years after the injury. On the other hand, best stay away form a physician, since they were the purveyors of what passed for science and medical knowledge in the day. Identifying illness as being caused by noxious vapours was about as close as they came to modern medicine, otherwise they were busy attempting to balance the "humours" of your body through bloodletting and so on. How this relates to nutrition? Since barbers were close observers and had practical knowledge of the human body though their profession, they would probably be able to tell you in a general sense if your diet was not right ("look at the tone of your skin. And your hair is thinning out more than it should"). While this isn't prescription level stuff, like "eat more fish", you would at least have an understanding from a professional observer that you should start thinking more about your diet, hygiene and other health related matters. [Answer] If a vengeful wizard banishes me to another dimension, it will be because I have done something to spite him. I will most likely have done this intentionally, because the bastard sure deserves it. I would most likely not be able to bring anything with me, because a wizard has no mercy. A wizard would most likely send me with just the clothes on my back and the shoes on my feet, and I would be on my merry way. I would be transported to some place in Northern Switzerland in a small, rural mountain community. I would be taken in by the friendly inhabitants of said village as a lost traveler, and set on my way. I would work as much as I could in such a place to keep a roof above my head and food in my belly, and probably would take in with a family that would be willing if I am not able to raise enough money to buy a house. As a previous commenter has said, it was not that people were getting poor food, in fact, the food they ate then were free of all this artificial, processed crap we are being fed today, and were eating much better than we are today (at least in America. I will hopefully know enough to stay away from their doctors, and just hoping beyond hope that I do not catch any sickness, because I will be very miserable and unable to work. If the villagers do not choose to take me in and cast me off as a spy, I will be forced to live in the wild by myself. I will try to trek through what I can in the hopes of finding another village, but if I cannot, I'm pretty much screwed without much basic survival skills. If I manage, somehow, to supplement my diet with fruits and berries and the occasional animal, that is, if I don't get poisoned by something I prepared poorly, I will continue a nomad-like lifestyle, carrying a burning stick and maybe some coals if I can manage to my next destination. I will fashion for myself a bow out of animal's hide and a stick, sharpening arrows on rocks to bide my time, and maybe fire harden a couple of spears to throw at a passing deer. I'll find myself a nice cup, maybe a rock, and customize it to my liking. I will have to conserve my energy along the way, resting frequently. It will be a hard life, but I may have a chance of making it through. This was a very interesting question; thank you for asking it! :) ]
[Question] [ In my story idea, there is a fluid material that also has many similarities to plasma. The strange matter (through means that I would also like to understand) converts regular forms of energy into something called cosmic energy, which (again, would like a realistic way of it doing this) causes things deemed improbable by quantum physics to happen. In short, one could do things like conjure fire or fly without breaking any natural laws, as long as they know how to use the 'loopholes.' It also distorts space-time, causing mirage like fields called transcendence fields, which exist in multiple areas of reality at once (so if it looks like an asteroid is flying towards you, get out of the field). This allowed intelligent 4D creatures to enter this dimension. 1 What would this plasmic matter be made of realistically? 2. How would this plasmic matter realistically convert energy into cosmic energy? 3. How would one *realistically* utilize this to achieve 'magical' things without defying quantum physics? [Answer] You want to make a new form of energy in space time (4D)? Then I have exactly what you need. Remember those lessons of radiation consisting of two fields, a magnetic and an electric field standing 90 degrees relative to each other? [![two fields](https://i.stack.imgur.com/SAIUe.png)](https://i.stack.imgur.com/SAIUe.png) Well, if we add the next dimension, we can have one more field standing 90 degrees on both of them. That is you 'cosmic energy'. Creating this field is rather simple, analogous to how a generator works by moving a magnet through a magnetic field, you can have an object with 'cosmic magnetism' moving through a combination of an electric and a magnetic field. This effect is caused by [particle spin](https://en.wikipedia.org/wiki/Spin_%28physics%29), a fundamental property that gets one more axis to spin about once we introduce 4D. Options: * Cosmic magnets can only be found naturally, and are extremely rare * Cosmic magnets can only be provided by the 4D creatures. * Cosmic magnets can be crafted, but only in the presence of a cosmic energy field. (Like normal permanent magnets are produced) Your transcendence fields can be explained by the fact that the field only partly propagates through 3D space, causing local distortions of space time. "Magical" effects can be produced by transmitting this energy to the place you want to use it, without the need for passing through the space in between, as the field only partly exists in 3D. ('fire' by just heating something with this wireless energy, of 'flying' by counteracting the gravitational pull of the Earth.) [Answer] 1. What would this plasmic matter be made of realistically? Unobtanium 2. How would this plasmic matter realistically convert energy into cosmic energy? Magic 3. How would one realistically utilize this to achieve 'magical' things without defying quantum physics? Unobtanium What you have here is a great excuse for some [applied phlebotinum](http://tvtropes.org/pmwiki/pmwiki.php/Main/AppliedPhlebotinum) (TV Tropes warning). You are looking for a vaguely sciency-sounding explanation for magic. The problem is that nothing in currently known science gives you anything like what you are looking for so the good news is that you can make whatever you like up. The bad news is that whatever you make up will have no scientific basis. You can always take some current scientific theories (for example String Theory or Quantum Physics) and pull some buzzwords out of it but essentially that's all you're doing. Dressing up your magic in science-sounding words. There's nothing wrong with that, Star Trek does it all the time, but you should be aware that it's what you are doing. ]
[Question] [ So we all know that [Lemmings](https://en.wikipedia.org/wiki/Lemming) are known for following blindly to their death but that is not the reality. I would like to create the myth in the real world, or rather I would like to know how such a creature could be created via evolution. * Creature must be a vertebrate * Creature must be at least as large as the average squirrel * Creature must follow a leader creature (specialized type) * Creature must follow without fear of death (if told to it will in fact run off a cliff) How would a situation like this come about via evolution and real world science? [Answer] Social insects, like ants and bees seem to fit well to your behaviour description, however, they are too small. The mammal species that has the most social insect like way of living is the [Naked mole rat](https://en.wikipedia.org/wiki/Naked_mole-rat). They are: * Vertebrate, check * As large as an average squirrel, check * Follows a specialized leader, check * No fear of death, well, they look really brave: [![naked mole rat](https://i.stack.imgur.com/X7VUgm.jpg)](https://i.stack.imgur.com/X7VUgm.jpg) (Go through the list once more and think "humans".) [Answer] Having intelligence actually makes this one easier. Brainwash individuals to do your bidding and send them out. Human's have done this for centuries. One of the earlier known cases are the [Assassin's](https://en.wikipedia.org/wiki/Assassins) (original). They trained to be killers and were sent out to kill targets dying if necessary for the "Old Man on the Mountain". We still have people doing that. The kamikaze during WWII, where the Japanese pilots made a one way attack on Pearl Harbor for their emperor. And today we have suicide bombers dying for the promise of 70 virgins and some power hungry nut job. It's much easier to train an 'intelligent' animal to kill itself for the good of 'all'. So human's meet all of your requirements. [Answer] # Brain infection There are a whole host (see what I did there) of mind altering infections in the world. Such as [Toxoplasma gondii](https://en.wikipedia.org/wiki/Toxoplasma_gondii), which cause mice to actively seek out the smell of cat urine, or [Rabies](https://en.wikipedia.org/wiki/Rabies) which causes uncontrollable aggression. Most of these infections bring about these changes to cause the host to conduct behavior that is conducive spreading of the infection. We could conceivably have an infection that manifests in filling some organ with a huge amount of pathogen, followed by a stage where the host runs uncontrollably. When the poor critter falls off cliff and impacts upon the ground it causes a small cloud of infectious splatter to whiff through the valley. [Answer] In evolutionary terms, a fear of death is a by-product of being required to reproduce at some time in the future, since those individuals without such a fear of death would be less likely to reproduce. However, if we were to evolve a species where we have two classes of individual, one reproductive, the other not capable of reproduction, the non-reproductive individuals could evolve behaviours that would be counter-productive for a reproductive individual. This is a fairly typical hive system. The only necessary evolutionary step would be for the non-reproductive individuals to be permanently non-reproductive, since as long as the potential for reproduction in an individual exists, it must have an evolutionary need to survive. Let us further suppose that this species environment contained many hazards of many different types, including geography, fauna and flora as threats. It may be too difficult to evolve to deal with all of these threats, but if a reproductive individual was accompanied by many non-reproductive individuals, then by observing the fate of these disposable individuals, the reproductive individual could by observation notice and avoid the hazard. Of course, the 'disposable' trap-springer would be disadvantaged, but its sacrifice would have increased the probability of its reproductive sibling successfully reproducing. Such a creature by necessity would need to be fairly intelligent, enough so that the breeder would be able to recognise that one of the disposables has suffered a mishap. Since the ability to communicate often comes with intelligence, it can be expected that a breeder could direct its related disposables to test the ground ahead for hazards. These would be indicated by audible means, either an "I'm OK!", "There's trouble!", or a death cry that would indicate a particularly dangerous hazard. Note that even if there were hazards capable of eliminating a disposable silently, the lack of the "I'm OK!" calls would be an indicator of a hazard. [Answer] Memetic evolution. Having a complete species of animals evolve to destroy their own fitness by suicide is very difficult. In such cases, it would be easy for the animals to evolve mutations which stop this behavior, and it would greatly enhance their fitness. However, it is nevertheless still possible to have a minority of the species act like lemmings, if a meme manages to spread within the population which encourages such behaviour. An example would be clergy. They are (mostly) self-sterilised by means of a meme (religion), and such groups have existed for thousands of years. They mainly survive by drawing new memetic converts from the general population, while its existing converts die out. It is not implausible for such a system to form in nature, and other possible examples include terrorist suicide bombers who willingly go to their death for their religion or some other memetic cause. [Answer] On a macro level, many animal species act like the made-up lemmings. Most of the time, predators and food supply keep the critters in check: 1. With lots of food and few predators, the animal reproduces quickly. 2. As the animal multiplies, they begin consuming the food more rapidly, and predators begin to increase 3. Eventually, there are more critters than food, and more predators than critters; the critters starve and/or are eaten. 4. With fewer critters, the predators die off and the food regrows, and the cycle begins again. But what if there are no predators? Islands often have very small, specialized ecosystems; it's not difficult to imagine an island populated by nothing more vicious than a [blue-coated critter with green hair and a long nose](https://en.wikipedia.org/wiki/Lemmings_(video_game)). In that case, the only limiting factor is food. But what if the food remains plentiful until a certain point, then almost overnight is gone? Rather than a slow, constant, more/less cycle, the food is almost a binary switch - food today, none tomorrow. This would have a huge impact on the survival of the critters. As their population grows, they come closer and closer to destroying their food source, wiping out the entire population. If their population grows too much, they may wipe out the species entirely. So, nature installs a switch. The critters are natural introverts; the more time they spend near other similar creatures, the more stress-induced chemicals build up in their brains. As their population booms, more and more critters accumulate chemicals. At first, the chemicals have little effect, but eventually they cause the critters to essentially go insane, their desire to be away from other critters overriding their self-preservation. The critters will begin chasing other creatures in an attempt to drive them away; a stampede of critters begins, sweeping up a large amount of the population, and terminating in the ocean. The more stress chemical acquired, the stronger the desire to chase, and those initiating the chase are most likely to survive. With a significant portion of the population gone, the rest calm down, and the cycle begins again: 1. Critters reproduce 2. Critters overpopulate and begin generating stress chemicals 3. Super-stressed critters chase the rest into the sea 4. Surviving critters begin repopulating I realize this answer doesn't fit the criteria of followers and leaders, but it is how I imagine "suicide lemmings" would act. ]
[Question] [ Well, we went and killed ourselves off with our stupid wars. But aliens come along, find our marvelous planet and the evidence that we were here and they find some human (and other) embryos in a base on the moon - in a crater near the pole that is never exposed to sunlight, so the whole base is in a deep freeze, in vacuum, not exposed to light. I theorize that they could remain viable for thousands of years in those conditions. But the aliens eventually find out how we killed ourselves off, which creates a problem for the humans among them. These humans, of course, result from those embryos, collected by the first ship and kept frozen... and then the aliens managed to artificially gestate them on their own planet. Now the young humans are on the second colony ship, landing on Earth along with a fresh batch of colonists and scientists. The question is: do I have to stick with a really short interval between our demise and the aliens' arrival for any information about us to survive - or could I postulate significant data storage in that moonbase remaining viable for thousands of years? In such conditions, could a computer and a data stick, perhaps along with various CDs and such, remain usable? Or should I make it a short interval - they came in response to a CETI and it's only been, say, a hundred years? Some book-type libraries on Earth would remain viable that long given a really good roof, fireproof construction and a dry climate. [Answer] The most durable information storage is having it carved in stone or in clay that then got burned. Our oldest writings are of that form, and they are thousands of years old. The main problem of this data storage is to explain why the information is stored that way. But maybe it was done intentionally by someone who was expecting the end of civilization, but hoped that some humans would survive and learn from that information later. He would have explicitly chosen a medium that can survive a long time. For more information about long-time information storage, probably the [Rosetta project](http://rosettaproject.org/) of the Long Now foundation is a good source. They use not stone, but nickel to carve the information in, enabling a high density of information. While the type of information they store is different, the basic idea is the same: Preserve information for a long time. Actually I'd be more concerned about the embryos: Given that the moon is outside the earth's magnetic field and outside the atmosphere, it is not well shielded against all types of radiation found in space (from solar wind to cosmic rays). Cooling doesn't help against radiation literally kicking your atoms out of the molecules. I'd expect the DNA to be considerably damaged after that time. [Answer] Data can be stored as strands of DNA. A DNA strand is essentially a linear, binary code, and it has excellent stability over time. There is [a helpful Wikipedia article on it](https://en.wikipedia.org/wiki/DNA_digital_data_storage). Here is a section from the first paragraph: > > It also has the capability for longevity, as long as the DNA is held > in cold, dry and dark conditions, as is shown by the study of woolly > mammoth DNA from up to 60,000 years ago > > > If the same set of information is stored in multiple DNA strands, say a thousand, then the aliens who find it could compare the strands to fix any random mismatches. For example, if one strand started with the equivalent of "000", and all the rest of the strand started with "010", then the aliens will know that "010" is correct. [Answer] A moonbase is actually a very harsh environment to try to store digital data. Strikes from cosmic rays will flip bits and corrupt data. Here on Earth, it's not too much of a problem because our atmosphere shields us from most cosmic rays. Even so: > > Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month. ([Wikipedia](https://en.wikipedia.org/wiki/Cosmic_ray#Effect_on_electronics)) > > > On the moon, these effects will be much worse. Of course, we can assume that the electronics on the moonbase are rad-hardened, so the majority of cosmic ray strikes won't affect them, but over time everything breaks down. Typical flash memory will only hold data for about 101 weeks (slightly under two years). Even unused HDDs will eventually be erased by thermal cycling ([Forbes](http://www.forbes.com/sites/tomcoughlin/2014/06/29/keeping-data-for-a-long-time/)), although in your scenario they may be spared this by never being in direct sunlight. Over very long time scales I would expect that the magnetic grains in the platters will diffuse and become unreadable, but at very low temperatures this might give you a considerable amount of time, maybe 200 years as a complete guess. We don't really have any information about the chemical stability of HDD platters under low temperature conditions over long timescales. I would be very willing to bet that even under ideal conditions, 1000 years would be a hard upper limit for any digital data. As others have pointed out, though, by this time it's almost certain you won't be able to find any viable embryos in the base. It's tricky to preserve living tissue without damaging it, especially if there's nobody around to monitor it. I'd say definitely no more than 100 years for this reason, and then only if there are a lot of redundant embryos to allow the DNA to be reconstructed even if many are damaged. [Answer] ## Paper. Sometimes the simplest solution is the most compelling. [The oldest surviving printed book](https://en.wikipedia.org/wiki/Diamond_Sutra#Dunhuang_block_print) is about 1150 years old. If we expand our search to all material printed on flexible organic fibers, we can double that easily -- [the oldest papyrus](https://en.wikipedia.org/wiki/Ebers_Papyrus) is about 2700 years old. Keep in mind that these have had to survive unpredictable storage conditions and the vagaries of human beings, which your storage cache would presumably not be subject to. Engraved or etched metal would probably be better but decidedly more expensive, time-consuming to write to, and bulkier to store. Some sort of metal-paper hybrid might be good to keep the size & weight comparable -- a metal foil, bonded to flexible fibers. The fiber backing would prevent tearing of the thin foil, and the foil would be more resistant to becoming brittle and crumbling. Being able to read your media without obsolescence-prone technology is important. Microfilm is an excellent example of future-proof storage technology. While not a viable enough medium itself to serve as a solution for this problem (silver-halide film "[can last more than 500 years](http://archives.utah.gov/micrographics/faq.html)", but I'd be concerned about radiation exposure, and it requires temperature-controlled storage), all it will ever require to read is a magnifying element of some sort (anything from a fancy collection of electronics to a chunk of clear, shaped crystal) and a bright light. For a real-life case study, the [Voyager record](https://en.wikipedia.org/wiki/Voyager_Golden_Record) is a fascinating & well-known example of attempting to create a media storage object & accompanying instructions for playing it, intended for interpretation by an alien audience. --- With all the radiation and generally extreme conditions found in space, I'm pretty concerned about the viability of human embryos at these timescales, so I'm going to take this a step further. Let's treat them as data and store them, too! Now, it's easy to say that you can just store genomes on paper -- but is it really a workable solution? Assuming we have perfect copies of genomes, they're about [3 billion letters](https://medium.com/precision-medicine/how-big-is-the-human-genome-e90caa3409b0) apiece. A very rough experiment (Verdana, 6pt, default margins, "gatc" repeated) gives ~13,000 characters per page => 230,000 pages. A typical box of printer paper is 10 reams (5000 sheets) -- so that's 46 boxes of paper for a single genome. Not great. This could of course be shrunk significantly by using an optimal typeface, minimal margins, double-sided printing, possible shorthand for letter pairs, etc. Still, that's a lot of paper, especially since you presumably want to store many embryos. However, there is a workaround! [Only about 0.1% of our genome varies between individuals](https://www.biostars.org/p/5514/) (ignoring rare variants). Thus, you can store a reference genome, and [diffs](https://en.wikipedia.org/wiki/Diff_utility) for individuals. That brings us down to 230 pages per person -- only half a ream, even at my original, highly inefficient & inflated calculation. To ensure sequence integrity, the genome could be encoded into binary and [parity bits](https://en.wikipedia.org/wiki/Parity_bit) (or other [error detection/correction techniques](https://en.wikipedia.org/wiki/Error_detection_and_correction)) could be applied to the data prior to printing -- but this would come at the cost of obfuscating the inherent readability of a plaintext genome. It'd certainly use a lot less paper, though. However you encode it, be sure to number the pages! Or at least [stripe the ends of them with a marker, punchcard-style](http://punchcardreader.com/striping.html). ]
[Question] [ After months of spending my time writing down my ideas, finally I've got the time to put into a readable format, [as an encyclopedia.](http://terminusnation.wikidot.com) However, there are a lot of threads I did not close yet, and in general, I'm unsure of the directions of expansions. In general, if I put my worldbuilding project into such a format, what are the things I always have to keep my eyes on? Are there such things at all, or is this question too broad? [Answer] What you're talking about is developing a system for organizing information. A visual chart would probably be quite useful. Within your universe define a list of major events which constitute its very foundation. Those are the ones that you should make sure are fleshed out, and that you would document first. For example: > > A creator type being comes into existence. > > > Then, the progression becomes natural. For each major event, create a list of important minor events which stem from it. > > It creates minions/companions, which become minor Gods, or angels. A point of contention arises between them, and some turn away from the Creator, and become "creatures of darkness". > > > Now you're really cooking. Make a "tree" of events which stem from one another, and just start documenting each branch. It will become visually apparent when a set of linked events are missing a connected piece, which you will have to explain before those original events start to make sense. Good luck! [Answer] As stated, your target is to organize information. And that is usually not a trivial task : information elements are linked to others, may be linked to space and/or time. So you can have different axis : you can for example use a geographical map to locate things in space, a timeline to organize them in time, some family tree coupling time and relationships between siblings, etc. Depending of the level you want to achieve, it can be quite a lot of information to keep in your head. You may want to use some tools to organize this. It can be simple notebooks and papers, or some software (I can think of the great [Tiddlywiki](http://tiddlywiki.com) here ; feel free to add suggestion in comments). If you are building this for a world or game, do not push it too much, as the world is mostly a recipient for your story, and not an end by itself. Structure your information around the hero or center of the story. As a side note, you can maybe find inspiration for both content and organization in some gaming systems like [Microscope](http://www.lamemage.com/microscope/). ]
[Question] [ Let's assume that a human colony was established on an exoplanet, dozens of light years from another inhabited planet, with the expectation that no one—not even the colonists' far-future descendants—could inform the outside world of their existence in any way, unless they launched a physical object off-planet. In other words, no radio signals, either because they're blocked or because they're jammed by another, more powerful radio source. Is there any pre-existing astronomical phenomenon that could provide this effect? The first thing that comes to mind is a planet orbiting a pulsar, but the radiation would be too intense for a human colony to survive. (Perhaps if it were tide-locked, and the colony were on the dark side? But that has its own problems…) Alternately, assuming the planet is far outside the edge of currently human-occupied space, could some kind of object, like a black hole, exist between the planet and the rest of civilization, blocking any signals? I'm not sure how plausible any of this is. In general, it should be possible for humans to live in sealed colony structures on this planet, and to walk on the surface in spacesuits, although the planet doesn't need to be terraformed or have a breathable atmosphere. [Answer] The question assumes interstellar radio communications is possible in the first place. We actually don't know this is true, because we've never successfully contacted any artificial EMR-producing device beyond our own deep space probes in the Kuiper Belt, in the outskirts of our own Solar System (but still only about 6 light-hours from the Sun). The big problem we have is the inverse-square law. Most of the radio transmissions we generate as a race that leave our neighborhood are more or less omnidirectional. That means that the power of the transmission, as received by an antenna, decreases on the square of distance, because all other things being equal your antenna is intercepting some fraction of the surface area of a sphere of the transmitter's broadcast, so at a constant carrier wave power produced by an antenna as essentially a point source, the surface area that energy is spread across is roughly (4/3)πr2, so as radius increases, the surface area increases on the square of radius, and therefore your antenna area as a fraction of surface area decreases on the square. Currently, the most powerful single artificial radio signal generator we have is the Taldom Transmitter in Russia. It broadcasts on two frequencies, the higher one (261kHz) is generated at 2500kW or 2.5MW. That sounds like a lot, and it is, but the very nearest star is 4.25 light years away from us. Radio waves can be measured in Janskys (it's a non-SI unit but based on metric measurements so it can be easily converted to the SI watt). A Jansky is a unit of wave power density equal to 10-26W/m2/Hz. The unit is common in radio astronomy because astronomical objects like stars involve massive amounts of EM flux acting across very long distances. Most astronomical objects outside our solar system have EM flux in the range of 1 to 100 Janskys. Given the transmitter's frequency and strength, the radio flux density of the Taldom Transmitter as detected by a ship orbiting Proxima Centauri would be on the order of: $$2500000 / \dfrac{4\pi}{3}(4.25 \* 9.461^{15})^2 / 261000 \* 10^{26} = 1.414 \* 10 ^{-7}\text{Jy}$$ That's 141.4 nanoJanskys. And this back-of-the-envelope calculation doesn't account for free-space path loss and other phenomena involved in interstellar EMR transmission. Basically, if you're broadcasting for anyone to hear, nobody can hear you. We could improve on that, dramaticaly, by making the signal directional. Ideally, if the Taldom Transmitter's power were directionalized with a parabolic antenna, say one similar to Arecibo (152m radius, 72583m2 area) that send the radio power laser-like out into space toward Proxima, the signal strength would be: $$2500000/72583/261000 \* 10^{26} = 13.197 \* 10^{21} \text{Jy}$$ That's about a quintillion times the normal radio emissions of anything else in our neighborhood, so assuming the antenna was exactly spotlighting the receiver, your transmission would blow out a dime-store transistor radio. But, all you'd need to block it is one not-very-large asteroid along the transmission path (or a misalignment of the transmitter antenna by picoseconds of arc; trying to hit your target planet with a radio transmission perfectly focused at 305 meters width of beam, in the grand scheme of things, is like trying to hit the bullseye on a dartboard, mounted on a G-simulation centrifuge at top speed, from 3 miles away). So, the answer is, you can very easily prevent the transmission of radio information between two communicating entities. An omni-directional "beacon" type signal, you wouldn't even have to block. A more directional signal could be physically blocked or misdirected with a solar sail or similar device somewhere directly in line between transmitter and receiver. [Answer] Give them a faulty interstellar transmitter and let them think it works. They're already pretty far out there. Any communication with a planet dozens of light-years away has a round trip time greater than 48 years (assuming immediate response of a planet 24 light years away). If you give them an interstellar communicator and they try it out, it won't actually send a message, then just have the equipment fake an incoming message in 50 years (if required). [Answer] To physically block the signal, the most likely option is interstellar gas clouds in a star forming region — not as solid an obstacle as a star or black hole, but still reasonably noisy, and the planet can be inside a gas cloud, allowing for blocking in all directions. However, this would also make it very difficult to find the planet to colonize in the first place. Without something in the way, absolute prevention of radio signals is probably impossible — you can overcome any level of jamming by adding more power, and adding more power only stops being an option when you are releasing enough energy to melt the planet. If you need that, the background energy is probably at unhealthy levels. At a more practical level, you don't need a pulsar — the average star is plenty bright enough to drown out any nearby signals. Most of the time a very bright star would increase the energy needed to stand out, but a dimmer star may be more effective overall, as it would allow a lower orbit, and any signals would appear to be coming from the already very noisy surface of the star. On top of that, a thick atmosphere would help a lot with blocking surface signals. As well as absorbing some wavelengths directly, it could allow a much more active ionosphere than Earth without increasing the surface radiation too much. [Answer] You mentioned that there exists a human colony. Do they need to retain their homo sapien nature? It is possible that the planet is in orbit around a star and an external factor (say a distant black hole) is gradually decreasing the size of the orbit. Or the star is growing old and is becoming hotter and more powerful. Such processes take hundreds of millions of years. Even the end of the solar system is predicted to cause the Sun to enlarge and heat up or something. It is possible that this human race would gradually evolve to the changing environment. Eventually the planet would get hotter, and get surrounded with gases from the star. This will probably lead to poor radio signal transmission. But humans may have evolved into more intelligent and climate-resistant species, and are still on the planet. ]
[Question] [ Can non-intelligent life forms evolve to leave their home planet and travel in interplanetary space, for instance, grow on atmosphereless icy moons and transfere spores over interplanetary space? [Answer] Yes, via [panspermia](http://en.wikipedia.org/wiki/Panspermia). Panspermia is the idea that extremophiles "hitch a lift", as it were, on ejecta from collisions between celestial bodies. There are a few obstacles, because the microbes would have to survive all three phases of travel: * Launch (as well as the impact event) * Travel in the harsh environment of space * Atmospheric entry and landing, with high temperatures Extremophiles are really the only types of organisms that could survive such a journey. More complicated organisms (with more needs) would surely die en route. On Earth, here have been some discoveries of materials related to organic matter that might be evidence of panspermia; see [Bell et al. (2015)](http://www.pnas.org/content/early/2015/10/14/1517557112.full.pdf) for one example. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Panspermie.svg/640px-Panspermie.svg.png)](https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Panspermie.svg/640px-Panspermie.svg.png) Image courtesy of Wikipedia user Beao under [the Creative Commons Attribution-Share Alike 3.0 Unported license](http://creativecommons.org/licenses/by-sa/3.0/deed.en). [Answer] Yes, but. Yes it can be done but I would list a few caveats. 1. Odds are the natural selection process is not going to select for surviving in space...why would it. Natural selection selects the individuals most fit in their respective environments. This simply means that if an organism makes it to space accidentally survival will also be random/accidental. 2. The more complicated the creature the less likely they are to pull this off. The more biologically complicated you become the more you are tied to your environment, mainly because you need more quantity and variety of resources. The most likely scenario in my mind is a single celled organism. The organism would be launched into space via natural phenomenon, to be trendy lets go with the ejection of water from a nice little moon called Enceladus. If there are single celled organisms in the theoretical oceans on the moon, the plumes of water vapor could contain little critters. Over time some could randomly have the ability to survive in space by essentially being dormant while they travel. Say they land on an asteroid or another moon that has the simple resources they need to survive...a particular mineral maybe and viola, you have your space faring critters. [Answer] If there was a low gravity moon with an atmosphere but in which its tallest mountains were so high that their tips were to stick out above the atmosphere then that could potentially lead to some life evolving to survive in the vacuum of space. Because the transition from atmosphere to vacuum on the mountains could be very gradual individuals that don't travel very far from where they started life might live with basically the same amount of atmospheric pressure as their parents. Over many generations populations could migrate however from regions with normal pressure on the ground to the peaks of the mountains that would be in a vacuum. As populations migrate up the mountains their skin and the openings to their bodily holes could become more and more pressurized to hold in their bodily fluids. Plants could also evolve to become more and more and more pressurized as they migrate up the mountains. Animals that fly would at first evolve more and more powerful wings as they migrate up the mountains but would eventually evolve to have smaller and smaller wings as wings become useless in a vacuum. Animals and plants living at higher and higher elevations might start to evolve to extract more and more energy from chemicals in the ground as it would be inefficient to extract energy from the air. Animals and plants on the peaks of the mountains would tend to evolve skin that protects their insides from deadly radiation considering that they would have no atmosphere to protect them. If there was ice at the peaks of the mountains life on the peaks of the mountains could use that as a source of hydration considering that water could not exist as a liquid in a vacuum. If some animals that live on the peaks of mountains use chemical defenses that involve chemical reactions that could end up getting modified into a means of locomotion as they could eject fuel out of their backsides in order to move. Animals that evolve this means of locomotion could diversify the fastest out of the animals living in a vacuum as they would tend to be able to travel the furthest the fastest. If the planet had multiple mountains that stick out above the atmosphere then animals that can move by ejecting fuel out of their back sides that evolve on the peak of one mountain could migrate to the peak of another mountain. If some of the animals were able to move fast enough using chemical propulsion they could escape their moons gravity and travel to other moons including ones that have no atmosphere as they would have evolved to live without atmosphere. Some of them could carry the seeds of plants as well as having smaller animals that can't use chemical propulsion hitch a ride on them so that they spread other animals and plants with them meaning that they moon hop in the same way that some animals and plants island hop on Earth. These types of animals would be the most diverse as they would be able to spread to moons that have no atmosphere where life could never have started. Some could perhaps evolve to eat parts of their gas giants rings so that they could get nutrients on journeys between moons. Some species could perhaps even evolve to subsist entirely on space junk and they could perhaps live entirely in space between moons and eventually between planets. Species that live between moons and planets could get very large as they wouldn't have to fight against gravity in the same way as animals on the surface of a planet and being very big could allow them to go longer without eating. Being very large would also allow for larger eyes that would be better at detecting food from large distances as in distances potentially larger than the radius of a moon. [Answer] There is no known reason to believe there is any limitation on what can evolve, simply because we do not understand the process to assign limits, so the answer almost has to be a default "yes." Escaping a gravity well is very tricky, requiring a lot of energy, but if there was a reason, there might be a species that figures out how to use things like winds, solar energy, and possibly a small packet of chemical energy to try to escape. I don't think it's likely (as in it'd be a miracle if it happened), but there's nothing in the laws of physics that forbids it. Waterbears are known to be able to survive the rigors of a deep vacuum, so we know its possible for organics to function in extremely inhospitable worlds. That all being said, when it comes to world building, we must always remember Sanderson's First Rule of Magic: > > An author's ability to resolve conflict using magic is directly proportional to the reader's ability to understand it. > > > This rule goes not only for high-fantasy magic, but science fiction magics as well. This species is highly "exotic," as in a real scientist would scoff at the possibility (but "can" is such a great open-ended word in a question!). You would have to make sure you don't resolve to much conflict with it unless you fleshed out why such an astonishingly unique species came into being. [Answer] There are three main routes to natural evolution into space-going life: 1. Panspermia is covered in other answers. I think that this is cheating though, as panspermia is planet-based life that travels through space in an inert form and then resumes life on a new planet. I don't consider it to be life in space, as it's not really alive in space. 2. Life could develop on planets and then evolve into something that can live in space. Note that this works best if there is a lot of life somewhere that is becoming progressively more like space. It needs to be a lot of life because space kills life optimized for planets. We need enough base material to leave room for natural selection. It needs to happen over a long period of time so that new generations can build life for the new circumstances. Note that panspermia may be a stage in this. 3. It is conceivable that life might find moments on comets or in a sufficiently soupy region of a nebula to develop in space. Maybe when we explore enough we'll find some. Note that there is Earth-based life in extreme conditions like volcanoes. Perhaps an environment like Saturn's rings could hold life. It seems like it would take a really long time to develop though. Realize that we think that what we now call one-celled life developed from even smaller life (e.g. we think that [mitochondria might have started outside cells](https://en.wikipedia.org/wiki/Endosymbiotic_theory)). Given how vast space is, it might be difficult for the life to encounter enough additional life to even get as far as one-celled life. It might still be stuck at the prokaryote stage or even the [protocell](https://en.wikipedia.org/wiki/Protocell) stage. Realize that it took something like 3.5 billion years for the first animal life to develop on Earth. This route may be slower than that. I'm assuming that what you want is to eventually get to a form of life that can reproduce in space. Perhaps you even want a form of life that can travel in space willfully. So a space plant that floats through a nebula collecting materials may not count. It seems at least potentially possible. We really haven't traveled far enough to disprove the existence of such life. Is there life on Mercury? Or the sun? We don't know. We haven't found life on Mars, but that merely suggests that it is difficult. I think that a form of life that travels via a solar sail, collecting material as it goes would be possible. I think that an intelligent race could create some. Since the universe is a big place, it should be possible for randomness to duplicate that feat -- somewhere. [Answer] some bacteria survives in space: <http://www.panspermia.org/bacteria.htm> They could be launched into space when their planet is smashed into fragments by an astroid. You can't get much more unintelligent than that. [Answer] Well, you said 'non-intelligent' but if we loosen the definition a bit I see an interesting option. How about custom made 'Pets' modified to live in space by an intelligent species. Think something like flying cats or dogs with large solar energy gathering 'wings', GMed to thrive in vacuum and naturally extract organics from rocks and space debris. 'Built' to aid in asteroid mining but then abandoned or escaped and gone wild. Perhaps very long lived and with 'natural' solar sails or other propulsion systems. Migrating back and forth from comets and small moons. Perhaps with enough time, they might evolve into a complex biome with multiple competing species. ]
[Question] [ For a near-future / alternate-history setting, I wanted to maintain the importance of some technologies and cultural fixtures that have already declined on our earth. As a first test, let's try one that doesn't have such a long history: Arcade games. I can't see this one being very important to the nature of the setting, but anyway... I know that arcades existed before electronic games, but I don't have a clear idea of what they were like. But once video games arrived, they became the dominant element. The heyday of arcades seems to have been brief. They've been in decline for 20 years. It's easy to see why. Most types of electronic gaming don't gain much if anything from being in a public place. And with internet communication, remote multiplayer games are possible. Is there any good reason why arcades could have remained important in the 2010s and be expected to remain important for decades more? "Slower computer development" isn't an answer. Consider those years to refer to a level of technology, not an exact year in our universe. "Hostility to technological and social change" isn't a good answer. I'm asking if there's any reason why game centers could be an optimal means of satisfying gamer desires. [Answer] Nostalgia and high-tech gaming systems. We have an arcade here in Portland, Oregon called Ground Kontrol. The cool thing about this arcade is (obviously in Portland) that it is also a bar. Arcades are cool, but they are waaay more fun if you can play the games while drinking a whisky. Ever played the [Simpsons arcade game](https://en.wikipedia.org/wiki/The_Simpsons_Arcade_Game) with a healthy buzz? It's a lot better. I imagine that arcades will always have a niche to fill. It's also possible that future highly immersive games, like full virtual reality systems, will require significant equipment costs, space to occupy, and bandwidth simply not available in a typical home. This would require people to come play at the arcade. If an arcade had a Matrix type immersion via [TMS](https://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation), the equipment to run that would be insanely expensive, but also insanely fun. I'd frequent the arcade for such an experience. [Answer] Consider that arcade halls and [LAN parties](https://en.wikipedia.org/wiki/LAN_party) are very similar to each other. In both, you have a a group of people getting together in one place for the purpose of playing computer games. The big difference, as I understand it, is that arcade halls were basically set up with single-player games. Because the technology wasn't very far advanced at the time, the games were also, by modern standards, relatively simple. But there is no reason why it has to be that way. I can think of two ways arcade halls could remain a desirable element from a gamers' perspective: # Access to some types of games is restricted. Maybe the government feels much more strongly than in our world about games where the action is centered around theft or violence. (That would probably cover a huge fraction of today's popular computer games.) Maybe the world took a different direction after a September 11-style event, instead opting to further restrict not just aviation but also things like flight simulators. These types of games or software could be restricted to a certain amount of play time per month or something like that. An easy way to do that is to only allow access to those games in government-run (or government-approved) arcade halls where play time is logged, centrally checked and logs regularly audited. Restricted access would be harder to police in a world where fast, easy, worldwide data communications is available basically to everyone, but you could make the penalties for getting caught with contraband games suitably harsh and the probability of getting caught suitably high, which would dissuade most people. Maybe game vendors simply never added multiplayer capability, or didn't expand on multiplayer capability beyond the most basic forms, to games available to ordinary people. There is any number of ways you could plausibly make this happen. # Add a significant element (social, perhaps) to the arcade hall experience that cannot readily be replicated elsewhere. Some ideas might be to offer unique multiplayer game experiences, or hardware that is so top-of-the-line and expensive that most people can't afford it, or some way and reason for people getting together just for the social activity and the game being merely an aside to that. A dedicated arcade game hall that charges per game or per hour could, in principle, invest in hardware that would be beyond the reach of all but the most devout players. This, in turn, could allow players to play games that are far beyond the ability of most peoples' computers to run at an acceptable performance. Consider that people still go to movie theaters, even though large-screen televisions, surround audio systems and high-quality digital copies of movies are available. Then, try to replicate the reasons why people go to movie theaters, but in the context of computer games instead. --- TL;DR: make it so that arcade halls can (and do) offer players something that they can't readily get at home, at a reasonably affordable price, and demand is likely to remain. ]
[Question] [ In a world where most grid electricity energy is from solar (with wind, hydro etc only supplying small amounts), you would need to balance out the load somehow. One idea I've had is to use "reverse peakers". Our current grid uses power plants that are relatively cheap by capacity (watts) but expensive per watt-hour to run, like diesel, to briefly balance load spikes. In this world, electricity demand that exceeds current supply is brought from other continents by superconductive power lines. However, this only has about 10% of peak generation capacity, so electrically intensive industries are done during the day. Most heat related energy needs, especially residential space heating is still done with natural gas. However to manage local excesses of energy, they would like time their use desalination plants to "reverse peak", to soak up excess energy. What would the energy density of this practice be like? How would it compare to normal hydro electric ponds energy density, assuming hydro storage has normal loss inefficiencies but desalination does not. This is because it's not being used to generate more electricity, it's an "offset" equal to the amount of energy it took to create, that would have been drawn from the electrical grid. Update: As used here, energy density is the total energy(watt-hours or equivalent) per unit of volume (Assume non hand-wavuim desalination for this portion, i.e. currently realistic). Bonus: If this society uses solar powered desalination to provide the bulk of its agricultural water, given hand-wavium solar panels that are ten times cheaper, but not more efficient, and ×10 energy inefficiency nano-prefix desalination, would it feel more like a utopia or a dystopia? (Yay! Bread-basket Sahara or Boo! Corn is $20 a pound) * Why do we desalinate? — World population of 30 Billion+, can survive without it but more comfortable with it! * Why do we mostly rely on solar? — Because fusion sucks, nuclear is "scary", fossil fuels are dirty and the other power sources I mentioned aren't available everywhere. * Why isn't there any grid level storage? — I am not aware of any good grid level storage solutions. That link to the superconductive based storage may change my mind, however. * How do people deal with cloudy days? — Continental grid can match local variances easily. Capacity is designed to meet needs in subpar conditions anyway. * Do we have any major issues (e.g. food shortage?) Lets add in the 30+ billion population for this too. Can we meet our food needs, presumably by lifestyle change or irrigating more farmland than before? How about luxuries like beef and alcohol? [Answer] > > However to manage local excesses of energy, they would like time their > use desalination plants to "reverse peak", to soak up excess energy. > > > This sounds a little convoluted? I believe you're trying to say that you have a civilisation with ample solar power and has a major desalination industry. During times of peak load, this industry ramps down - as it prefers to run on cheap, off-peak energy. However, from this point the impacts on your civilisation depend entirely on the many factors that got it to this point, as well as external factors. These factors are not addressed in the Question, so it would be pure speculation. Key factors include: * Why do we desalinate? * Why do we mostly rely on solar? * Why isn't there any grid level storage? * How do people deal with cloudy days? * Do we have any major issues (e.g. food shortage?) Lastly, I'm not entirely sure the question about 'energy density' makes any sense - are you asking how much water could be desalinated per kWh? In which case a trivial google returns [3-5.5kWh/m^3 for Reverse Osmosis.](https://en.wikipedia.org/wiki/Desalination#Energy_consumption) As a fun factoid: > > Supplying all domestic water by sea water desalination would increase > the United States' energy consumption by around 10%, about the amount > of energy used by domestic refrigerators. > > > --- Based on the answers to some of my questions earth has a 30 Billion+ population. This means the world is drastically different from the one we know today - on one hand they have greatly different problems and on the other they must have solved a lot of those problems to get 30Bn+ people. So on one hand, I have a hard time believing that they don't have grid level storage, nuclear energy, and significant other renewables. On the other hand, I can easily imagine large solar component and excess energy being used to desalinate water (at around ~1kWh/m^3). I'd also expect that these people are experts in waste recycling and intensive farming - hydroponics, algae farms and 'growing meat' are modern day forerunners. They likely will have replicator like technology! [Answer] Practical superconductivity would change everything. If your superconductive material could withstand extremely high magnetic fields, (which tend to force conductors to stop superconducting), energy could simply be stored in a ring shaped superconductor. Energy is added and removed using wire coils wrapped around the ring. Such rings could be buried under each facility and house, saving up excess energy generated during the day and returning it during the night. There'd probably still be some kind of power network so that excess energy could be distributed. If you were short of power in one place it could be brought in from somewhere else. Super small rings could be used to power electronic devices for years instead of hours or days. One day you might buy an electric car that will be fully fueled when you receive it and never need refueling. [Answer] [Wikipedia](https://en.wikipedia.org/wiki/Desalination) has already sorted this out for you with a nice overview of energy consumption for the numerous methods of desalination. In a nutshell: assume 5 to 10 kWh/m³ for a more realistic approach. The article also claims that more than half of the total cost of desalination comes directly from energy cost with a total cost in the range of 0.45 to 1.00 Dollar/m³. Say Megapolis with 10.000.000 inhabitants and 4.5 m³/inhabitant/day (taken from 1630 m³/year per-capita for the US - world record! - this ammount obviously includes domestic, industrial and agricultural use) would result in 450 GWh per day (1.6 PJ). Quite a number and if you can find a spot to store large amounts of water this could be a part of demand-side-management. ]
[Question] [ In my world, a web of space stations was built around the planet to save humanity from ~as of yet unspecified horrible disaster~. Now, it's been a thousand years, and the space stations have begun to disintegrate. If my protagonist gets trapped inside a module which falls from the sky to earth, would there be any way he could survive reentry? Perhaps the stations are not too far from the surface (but then, they would have all long come down). Perhaps it falls into the water (but he probably can't swim, so perhaps it was shallow water?) Perhaps the module is very heavily built? I'm up for anything that doesn't completely beggar belief. [Answer] Unless the module was designed to survive reentry, then no. Not even by accident. Surviving reentry from space not only requires the module to survive but it also requires the capsule to be gently decelerated before it slams into the ground. So far we've only figured out how to do this with only aerodynamic forces on wings or parachutes OR aerodynamic forces combined with last minute retrorocket thrust. So unless those systems were built into the capsule, along with the control mechanisms to activate at the appropriate times, your protagonist would end up as a pile of unattractive goo at the bottom of the capsule even if the capsule survived. But if your space stations were built centuries ago, then perhaps everyone forgot that certain modules were intended to be used as emergency reentry capsules. [Answer] I disagree with the accepted answer. Survival is possible albeit extremely unlikely. There are two aspects to the survival: 1) Surviving the fire. This is not going to be possible for anything that we have currently put into space but you are indicating a far greater space presence. There might be something big enough to shield you on the way down--say, perhaps, a piece of radiation shielding made from mining slag? 2) Surviving the landing. There have been cases of wreckage-riders that survived landings at terminal velocity, albeit with serious injuries. There has also been a case of a true free-faller surviving with apparently no injuries. (He was injured when he jumped and had blacked out on the way down so we don't know exactly what happened. It appears he hit a pine tree just right and then deep snow.) Thus your protagonist could ride a piece of radiation shielding through the fire, then fly away on his own (note: this assumes he has skydiving experience!!) and get extremely lucky in where he comes down. (I'm saying to get away from what you rode down because it's going to be much harder to slow down. The pine tree that saved the tail gunner above would be of no help if you're riding something big.) [Answer] Anything is possible. That said, riding the module down to earth is probably suicidal, as it will hit land or water hard enough to kill anyone, assuming that the heat of re-entry doesn't do the job first. The most likely means of survival is to get into a space suit equipped with a parachute and [bail out](https://en.wikipedia.org/wiki/Space_diving) before the module gets below the upper atmosphere. We can assume that the builders of the space stations anticipated an emergency that might require that the occupants return to earth without benefit of a spacecraft. [Answer] The space station manufacturer did include airbags..... didn't they? ;-) Translated - it completely depends on the safety features built into the space station and environs, and nothing else. The question is a bit like asking "can a person survive <some kind of collision/fall/failure> of any manufactured object they happen to be in." It depends on the safety mechanisms the manufacturer built in, and/or any other sources of safety/mitigation that might exist, and not at all on where it falls from (space or any other location). ]
[Question] [ I am writing a story with an immortal race of aliens with psychic powers. Their minds are separate from their bodies and located in a pocket dimension inaccessible to ordinary matter. Their bodies are psychicly animated stone or metal. Notable points: * They can die temporarily (ie: get disconnected from their body) by being crushed or vapourised. They can re-animate their original body or construct a new body from material in a 100m radius of where they died. They can also die permanently if they run out of energy and have no way of getting more. * They can only control one body at a time. Only one immortal can control one body at a time. Control over their bodies relies on the (cross sectional) area of each limb, stick-like limbs are not as strong as tree trunk-like limbs. * Older immortals are more powerful than young ones. Old immortals generally control larger bodies and have more powerful psychic powers. Immortals are motivated to have large bodies because this gives them increased awareness of the world around them. They can only communicate and interact with each other through the physical world, mind-to-mind communication is impossible. Their bodies act as an 'anchor' and allow them to interact with the physical world so the loss of a body entails complete loss of contact with everyone. * They reproduce slowly (compared to humans) with a new generation every 250-500 Earth years. Reproduction is like mitosis, the mind splits a little bit off. This mind fragment will have to construct a new body for itself. * Cancer or other diseases are not an issue but they need to absorb energy or they will become less powerful and later completely impotent. Energy can be absorbed as Heat. They take advantage of the energy gradient between their home dimension and their body in order to absorb energy. Using their psychic powers drains energy and they can absorbe energy through their stone/metal bodies. Larger bodies require more energy (proportional to the weight that needs to be moved) but can also absorb more energy (absorbsion is proportional to the surface area of the body). * The immortal aliens prefer hot rocky planets, like Venus and Io (Jupiter's Moon) and are currently about Kardashev I or a little below. They can only use solid rocks or metal for their bodies and have access to most surface minerals. They are not a highly technological species, they prefer to use their psychic powers. They only need energy (solar prefered) and a suitable material for their bodies. Material for shelter is optional. They can only anchor to solid objects. * Their psychic powers include Telekinesis, Levitaion and Pyrokinesis. Moving an object telekinetically requires the same amount of energy as moving it by normal means. The same with Levitation and Pyrokinesis. Using the body to move objects is more energy efficient than using telekinesis. Since their body acts as an 'anchor' for the mind, destruction of the body means a loss of access to psychic powers. Creating a psychic effect further from the body uses more energy, proportional to distance. (Probably the square of distance). New mind fragments can control up to $0.0664\, \mathrm {m^3}$ of material (thats about human sized) and each century they can grow between 20% and 30% larger (volume). A new mind fragment starts anchored to a $0.1\, \mathrm{m^3}$ of suitable material at a temperature of 450°C. The alien mind requires a bare minimum of 1220 watts of energy, but 1500W is the recomended minimum. The energy requirements of the brain increase by an average of 20% every 50 years. New mind fragments can borrow energy from their 'parent' if needed. Assume that their methods of gathering energy from the sun/ambient heat are only ~~1%~~ (see Edit below) efficient. Each immortal alien needs enough room to gather energy for itself and to defend its energy gathering area. More power is better young immortals will need to defend their mineral deposites and collection areas from older immortals that want more energy and 'real estate'. For the sake of the question, energy is in demand. I can forsee these immortal aliens building sun pits (?) that focus light and heat into a small area. Would the Sqare-Cube law prevent them from growing past a certain point? When would population become an issue? Which of energy absorbsion or living space become an issue first? How would their civilisation form itself? What other issues might they run into from being immortal and having these psychic powers? Edit: As per my coment on Murphy's answer, newborns have a heat-to-energy efficiency of 20%-30% which stays constant for the first century but then drops to 1% after about a miilennia. This (correctly and awesomely) means that "the oldest, largest and post powerful would also be the most greedy". [Answer] ok, so they must remain solid. > > "The alien mind requires a bare minimum of 1220 watts of energy, but > 1500W is the recomended minimum." > > > "Assume that their methods of gathering energy from the sun/ambient > heat are only 1% efficient." > > > " A new mind fragment starts anchored to a 0.1m3 of suitable material" > > > These statements combined are problematic, they imply that they need to absorb a constant flow of a minimum of 150,000 watts as newborns. . That's a lot of energy. Focus that much on anything with a surface area of only 1.3 meters (cube with a volume of .1 meters ^3) and it may be problematic. Even assuming it's being sucked away into some cold pocket universe near the centre this is going to be tough to avoid the outer surfaces melting or turning to gas. 115.4 kW per m^2 is a lot. that's about ~~ 85 × electromagnetic energy flux of the sun on Earth (solar constant) and ~20 times the electromagnetic energy flux of the sun on mercury. Even if your newborn is made of copper, hammered flat and painted black they're going to have trouble not starving even in direct sunlight on mercury. You might want to up that efficiency from 1% unless you want energy problems to be really brutal. lets assume they can use any metal. metals and minerals with an extreme melting point like Tungsten or Tantalum hafnium carbide(melting point of 4,215 °C) are going to be some of the most valuable and fought over comodities because they allow for maximum heat tolerance while copper is likely to be popular for the young and poor since it would allow fast absorbtion at lower temperatures. So surface area is the important thing. Can they store a large quantity of energy? Can they change body? If so older, rich immortals are likely to have "feeding bodies" that look like big CPU cooling fans made of Tungsten or similar high-temperature material which they could submerge in vats of liquid iron to feed as much as possible and combat bodies optimised for durability and strength. ![enter image description here](https://i.stack.imgur.com/2oMnQ.jpg) If they can't change bodies or store a lot of energy then they'll likely go with the Tungsten bodies but with more practical shapes and perhaps lunglike pumps for when they want to have a "meal" of heat to pump liquid metal across fanlike internal surfaces. But that's for the old and powerful who can control copious supplies of energy. The younger ones are going to struggle more. the very poorest will simply bask in the sun with cobbled together mirrors focused on themselves in rock bodies and expend the minimum energy at night in an attempt to not starve. The "middle class" might have metal bodies and perhaps arrays of mirrors focused on vats of molten salt. Extreme cold will be a potent weapon, exhaust an opponent and drench his body in LN2 and he may not even have enough energy to reclaim a body. Edit: > > "each century they can grow between 20% and 30% larger (volume)" > > > "The > energy requirements of the brain increase by an average of 20% every > 50 years." > > > Along with declining efficiency this would mean that as they get older their requirements increase faster than their volume so eventually they would starve but could put it off or a long time by turning themselves into vast constructions of heat fins submerged in molten metal. So not truly immortal. [Answer] Would the Sqare-Cube law prevent them from growing past a certain point? When would population become an issue? Which of energy absorbsion or living space become an issue first? How would their civilisation form itself? Unfortunately I think this premise: > > The immortal aliens prefer hot rocky planets, like Venus and Io (Jupiter's Moon) > > > Isn't what would actually happen. Once they achieved space, your species would be far better off to simply stay there instead of going back to a planet. Unlike humans - who need crazy things like ecosystems and air - your aliens are perfectly happy floating around the asteroid belt, and it offers a lot of advantages. 1. Space - in the sense that they get a ton of room. Instead of fighting over the pitiful land area of a planet, your aliens can now spread out over entire planetary orbits. This gives them access to a massively increased amount of energy. 2. Gravity - namely, the lack of it makes their psychic abilities a lot more powerful, and largely eliminates the square-cube law. I envision that the aliens would create giant concave mirrors to focus solar energy, then nestle their actual "body" in the center. This also gives them a backup if their body is accidentally destroyed - they can take part of the mirror to reform. They could also use parts of these mirrors to communicate across the solar system, flashing messages to each other by slightly modifying the refraction or angle of the mirror. Elders will want to be as close to the sun as possible, to maximize energy. Younger aliens will need to be further from the sun, slowing their development. However, this offers the possibility for an economy. As resources grow scarce (asteroids mostly used up) you need to go further and further from the sun to find more. Elders would offer young aliens time in their mirror collectors (probably fractions of an orbit) in exchange for raw materials. So you'd end up with Elders closest to the star, with truly incredibly large mirrors - some might even be able to counter gravity and turn into [Statites](http://en.wikipedia.org/wiki/Statite). And out from that would be increasingly more numerous but younger aliens, all trying to compete and create larger collectors, and trading/bartering energy for useful components to increase the size of their mirrors. So basically, a race that naturally forms into a [Dyson Swarm](http://en.wikipedia.org/wiki/Dyson_sphere#Dyson_swarm). What other issues might they run into from being immortal and having these psychic powers? I have a suspicion/hypothesis that immortality is an evolutionary dead end. On earth very few organisms are immortal, and most of those are very simple compared to a human being. The more advanced ones that I'm aware of (such as [lobsters](http://en.wikipedia.org/wiki/Biological_immortality#Lobsters)) have another mechanism that limits their lifespan, so while they're technically immortal in practice they aren't going to live forever. The problem, as I see it, is that immortality is selected against on a species-wide level. There's a common misconception - I think stemming from the phrase "survival of the fittest" - that evolution is about creating the most powerful, fittest individual. But that's not the case at all. Evolution is more about which species are best adapted to their environment, and over long enough periods of time, that requires flexibility. Because environments change. But an immortal species is in a trap. They've gone for more powerful, immortal individuals, but that means they've stopped - or slowed - how fast they evolve as a species, which reduces the chance that they'll be able to adapt if/when conditions change. This makes me think that for an immortal sentient to evolve, they need to have some other mechanism that either 1) makes them functionally not immortal, like lobsters, or 2) they need to be able to adaptable/flexible as individuals, not just as a species. So you can't have immortal elder aliens who are hidebound and reactionary - they need to be forward-looking individuals who can change tactics and strategy as the situation demands, giving up cultural momentum if the situation demands it. Maybe even evolving themselves as required, the equivalent of conscious gene manipulation. [Answer] Eventually, the elderly would basically have to fling themselves into the sun for energy to meet their requirements. They would have to move closer to the sun, on a slow but regular basis to meet energy needs. The biggest question is how much heat can there bodies actually and minds actually handle. A temperature of 450C is basically a lifeform that needs to exist near lava on a planet. At what point do there bodies or minds simply melt or burn up? They would have to form a shell around the sun at the minimum safe threshold. [Answer] The adherence to normal energy ideas makes this proper SF with a modified universe. That is, you can be strict about applying your rules and forming plot points through their limitations and side effects. Keep up with that as a defining concept. Because of that, it makes sense to ask about square-cube law and a few of the other points you ask. How are the golem bodies being animated? not muscles or hydrolic jacks in the limbs, and it is those things that have strength proportional to the cross section area and weight proportional to their volume. So no, the square-cube law does not apply. How do they move? Somehow they can apply force to invidual mineral grains or rocks (through another dimension it seems) and thus move the components of the statue as well as being able to move an object directly. So why would he move or need limbs? Animating the rock of the arm to then push on the object is just wastful if they can move the object directly. Since you mentioned bodies made of (only) certain materials, there may be limits on what they can apply forces to or how effecintly they can do so or how easy it is for them. So what is it about "rock" that is different from other materials? Maybe they like silicon atoms or particular chemical bonding configurations, so some minerals are better than others and simple material made of few kinds of atoms don't give them any grip from their home dimension. How do they feed off heat? The home dimension or some different one could serve as a cold side to allow heat to flow. The hot environment of Venus all around their control region projection into our universe (whatever that is) can serve as energy that can flow into a different cold universe dimension. That means they can remove heat from their surroundings, an implicit power that can be directed for that effect. Update: their whatever projection into our space doesn't feed by itself. It is the control over minerals that can work in the other direction, the thermal motion applying force to their "grip" and generating power. Naturally the entire volume of their body serves as energy-harvesting apparatus, not just the surface. What limiations arise: they may have a capacity on how much they can grip. So materials inefficient for gripping consumes the capacity but is hard to control and is less efficient at feeding. They want most efficient mineral types, and highest temperature that allows said minerals to exist. Living space or energy absorbtion being an issue first? Insufficient data. How much space does their projection into our reality take? If that is their power source, then they can be smaller in hotter environments, explaining their preference. Also they can push the minerals that exist there, but not ice, methane, etc. so they would be powerless on a comet. So to quantity the answer, you need to set values for energy needs and gripping efficiency re feeding off heat. Maybe gripping more stuff uses effort, so larger bodies require more energy. If the feeding flux is less than the overhead, they are losing energy to control more. If they need a particular heat flux to live, be alert, be happy, etc. that would give a sustainable resource level to each world. Can they go inside the planet and soak up heat there? Why not the sun? Why do they want to move physical objects around? Do they make chess pieces or something? It's not for feeding or manipulating their environment for living conditions. [Answer] @murphy's answer about heat sinks makes me think. I suggest that the entire volume of gripped minerals (since they're being held through the 5th dimension), but that removes the heat from it which must be replentished from the surface. They may have a working volume made of minerals that they optimally grip, as well as they can obtain. But that is connected to other material with good heat conductivity or adaptors to withstand harvesting hotter sources then their main mineralmcan handle. If they can't directly grip pure metal at all, they need limbs and digits made of the controllable stuff. These may be ad-hoc pseudopods, or maybe well-practiced limbs are easier. They don't have to be contiguous. A digit may be on the outside of layers of non-controlled matter, as long as it's in range. It can even be loose, hovering near by. Imagine a detachable hand! Hovering uses constant energy that a piller supplies for free passively, so it's used sparingly. They can make their bodies into tools for constructing their extended bodies and environments. I hope you run with this, and write an interesting story like Robert L Forward's aliens. A zoölogy treatment would be an interesting microfiction. ]
[Question] [ Can large amount space debris be used to block sunlight from falling in a particular land area (about the size of Hawaiian islands)? If so, how much space debris will be required? What will be the environmental effects of this other than just lack of sunlight (i.e will it alter the climatic conditions)? [Answer] In short (TLDR): Fourier Optics and Lagragian Point L1 The answers up to now have correctly identified that anything "in orbit" is going to move, and that the earth is rotating as well, thus making a very sticky problem for the evil genius in question, who is trying to block off light only to the island chain of Hawaii (or wherever specific place he has in mind). However, there is a solution to the movement dilemma: The Lagrangian Points. The Lagrange Point L1, which rests inline between the Sun and the Earth, would be the spot for our evil genius to construct a massive cloud of space debris. The L1 point is formed at the sweet spot between the Earth and the Sun where the orbital period is exactly the same as the Earth, thus allowing the "cloud" to remain inline with the Sun from the Earths perspective. I'll consider this "cloud of debris" to be more of a space engineering mega project, composed of millions of smart satellites, which can make a structure on the same order of size as the diameter of the Earth. The L1 point is unstable, hence, the satellites must be actively controlled to keep station at their necessary positions, relative to each other and relative to the L1 point. Having now constructed a massive shade, the next issue is forming the eclipse umbra. Light from the Sun will diffract around the edges of the shade(s), and as the Sun is not a perfect point source, the shadow created by a single circular shade is soft at the edges. Hence, Dr. Evil (now our evil genius has a name) can't form a crisp shadow, at least, not likely at 1.5 million kilometers. He could shade the entire planet, provided the shade is large enough, but only shading a specific point is harder. This problem has a likely solution: Fourier Optics. You've experienced this if you've ever played around with a laser pointer that comes with a set of image masks. Normally, the laser pointer makes a coherent beam that is sharply focused. To create a grid, a smiley face, or some other image, you insert a mask in front of the aperture. This mask uses Fourier optics to construct those cool patterns. The same principles can be used by Dr. Evil's formation of satellites to create a shadow, and having active control over the formation would allow for the shadow to follow Hawaii as the earth rotates. <http://en.wikipedia.org/wiki/Lagrangian_point> <http://en.wikipedia.org/wiki/Fourier_optics> [Answer] Yes and no. It depends on what you are looking for. Do you want no light to fall on one specific area ever? Say block all light from Washington D.C.? Not really, you could possibly block light the size of DC but it would move around as the Earth spins. You have three things you need to deal with when 'blocking the Sun' you have the Earth (with a tilted axis) traveling around the Sun, the earth spinning on it's axis and the 'debris' either orbiting the Earth, or the Sun between the Sun and Earth. To keep the debris directly over a location it would basically be a geostationary orbit, but it would only block the sun around 'noon' depending on the size of it and the season. In this case it would also act like an extra moon at night as well. Unless it was very large and blocked a lot of sunlight from a large part of the Earth it would not make a lot of difference. Now if you had something that acted like a permanent lunar eclipse that would start to cause some issues and could start cooling the planet. There are theorized human projects to do things like this both to increase the energy arriving at Earth and to decrease the affects of global warming, but they would take a concerted effort to perform, not just some Dr. Evil ransoming for money. [Answer] The answer to this question, to the chagrin of super villains everywhere I am sure, is no. Specifying an area that targeted on a global scale cant be done in part due to the size of the Sun vs the Earth as well as the atmosphere diffusing light (redirecting it in all directions as it comes through). I suppose you technically could keep it from getting direct sunlight which could have a very minor effect to climate/temperatures but the temperature impact would be mitigated by diffusion and perhaps more importantly the ocean, since we are talking about Hawaii, now an inland location may be more (minimally) impacted by this scenario. The cost to create and maintain such a structure would be, dare I say it, astronomical and for the greatest impact you would need it in the lowest orbit possible which...again considering its necessary size would be pretty darn far away, so in the end, totally impractical and as practicality is often moot here, its also not going to be effective in impacting the location in any meaningful way. [Answer] I think one answer might be that small unmanned spacecraft are programmed to track down and latch onto space junk, and drag it in between the Earth and the Sun. Once there it could linked to others. Large fields of Space-shade could be moved at once from the ground to make it more or less shady as needed. It could be the next gold rush, private companies could and would compete for this work. The big question is not if it's possible. ..the question is who will control the shade? "We can't have a "Shade Gap!" ]
[Question] [ I've read [this answer](https://worldbuilding.stackexchange.com/a/100311/2169) and it was insightful, but I'm describing a character who undergoes a one off transformation rather than being from a whole new species. She grows fangs (both upper and lower canines) like a baboon, without her skull shape majorly changing (no snout, but still room for the teeth and new larger jaw muscles.) [![open mouth of a baboon with prominent fangs and tusks](https://i.stack.imgur.com/cf51em.jpg)](https://i.stack.imgur.com/cf51em.jpg)[![baboon with a closed mouth](https://i.stack.imgur.com/C6HBYm.jpg)](https://i.stack.imgur.com/C6HBYm.jpg) [![skull of a baboon with interlocking fangs and tusks](https://i.stack.imgur.com/DseBS.jpg)](https://i.stack.imgur.com/DseBS.jpg) The upper and lower canines she has are larger than those in the above image, but I can't find a better reference. She can close her mouth and seal her lips, but the lower and upper canines are large and interlock as shown in the image of the skull above. The linked answer mentions "bilabial stops (/p/, /b/ and nasal /m/)" and "labiodental fricatives /f/ and /v/" being potentially unaffected, but rounded vowels being difficult. Would this also apply to someone who didn't grow up with that mouth? What kind of believable changes to her speech and expression would one expect? [Answer] ### Not Very Much This I think will be a frame challenge based on your clarification. How It Can Work: Girls With Fangs speak for themselves! The very best way to find out exactly how much speech will be affected without doing this to do this yourself is to watch and listen to people with fangs actually talk normally. Humans, as we know, come with canines pre-installed. We have two uppers and two lowers. And our canines come in a wide variety of shapes. A lot of people have kind of nondescript squarish canines, while some have pointy fangs. Some of us who have fangs have short fangs and some have longer, more prominent fangs. Apart from what Nature has provided, it is possible through the wonders of modern cosmetic dentistry and advanced materials, to make and apply a wide variety of artificial 'super fangs' that will more closely mimic what has happened to your character. These can range from the cheap plastic things you'd find in a costume shop all the way through the spectrum of properly molded clip on veneers to permanently cemented contoured caps and all the way to permanently implanted fangs (either as individual teeth or as part of a complete or partial arch). [Clip on molded fang with arch](https://www.youtube.com/watch?v=f6T80Gxp9IU). Apart from several obnoxious speech habits, this girl doesn't complain of any oral discomfort and can enunciate very well. [Fang overlays](https://www.youtube.com/watch?v=5NJqB3r0ll4). This girl does complain of some slight lip protuberance but otherwise seems to be unaffected. These are removable and available in set sizes. [Custom dental work](https://www.youtube.com/watch?v=hMiH1PnGoGM). This girl had cosmetic dentistry performed, including permanent bonding of artificial tooth substrate which was subsequently shaped by hand. She appeared to have no difficultly with speech. Mind you, none of these fangs rise more than perhaps a third of an inch above the average tooth height. And none have cosmetic lower fangs at all. Your girl with the baboon like fangs will not likely encounter any particular speech issues. She should be able to pronounce any sound relatively normally and there should be no sounds she can't pronounce. In reviewing several videos with larger cheap fangs, the only obvious defect was a kind of obvious lisp or muffled enunciation. Her problems with the sudden appearance of very long fangs (perhaps as much as an inch long) will be getting used to how these teeth fit in her anterior mouth --- she'll be biting her lips and maybe even lacerating them terribly. At least until she gets used to her new oral arrangement! If the Change properly rearranges her dentition, soft tissues and gums all at once, then accustoming herself will be relatively easy. If the only thing that changes is her actual canine teeth, then she won't even be able to close her mouth because human canines don't slide by one another the way baboon canines do. The lowers will become jammed behind the uppers and she won't be able to talk or eat or even close her mouth at all. Why It Won't Work as Described: You specify "without her skull shape majorly changing" and also specify that your character has two inch long upper and lower canines (fangs) and also that these huge teeth exist in what is essentially a human proportioned skull and that she can close her mouth and lips. You also specify that she has tusks in addition to fangs. I'm very sorry to report that you can't have all of that. Several of these options are absolutely condradictory. The roots of those upper fangs will literally close off her nasal cavity and most likely displace her eyes and maybe even parts of her brain. Human facial bones are not that robust, and there is a very good chance that she will catastrophically lose those fangs and a whole lot of her maxilla to boot. The lower fangs are just barely conceivable, but again, the human mandible is not designed to serve as the foundation for such oversized teeth. In any event those four teeth together will crowd out and completely distort her dentition and her midface. Her incisors will be jammed together into a very narrow space and her premolars will be pushed out to the side. Small fangs are bad enough for biting lips --- with teeth like that, she is literally going to shred her mouth. Chances are also very good that her displaced premolars and incisors will lacerate her cheeks and lips. If you insist on tusks, which are teeth that grow outside the mouth, like those of a walrus, she'll face the same shredded mouth problem. Plus she won't be able to close her mouth or lipsproperly. Best case scenario is that she runs to the nearest dentist and frantically gesticulates to her baboon fangs whilst writing a message, because she won't be able to talk intelligibly, will be bleeding all over the place and probably won't be able to breathe. And when the dentist is done grinding them down, she's going to need to see a craniomaxillofacial as well as ENT/plastics surgeon to correct what's happened to her mid face. Those fangs are going to have to be cut out and she'll have to be reconstructed. Conclusion: You can have a relatively unaltered human skull, the ability to close the mouth, the ability to close the lips if you go with small fangs. As you can hear, your character would talk fine. If you insist on baboon sized fangs, you can have the ability to close the mouth, but not have the relatively unaltered skull. Your character will also have to deal with the unintended sequellae as described. If you insist on tusks, then you can not have the relatively unaltered skull or the ability to close the mouth or the lips which contradict three conditions that you set up. [Answer] You have a lot of lee-way around this because there are no examples. Humans have an immense amount of muscular control around our lips and tongue compared to other animals, and the entire complex system might be adjusted to allow proper speech, although the tone and timber would be deeper due to the larger speech cavity. Without "magical adjustment," however, you'll have significant issues. If they jut out of her mouth, both up and down, then she'll have a bad lisp. If you can't produce a proper seal around the teeth, you'll loose P and B. V's and F's might also be impossible, and OO would sound like u in shut. Possibly a bigger impact would be the larger jaw bone that goes with the teeth and stronger jaw muscles. That would change the shape of the tongue and mouth, possibly requiring retraining to make any consonant sounds at all, and shifting all vowels towards a schwa. Update: With the clarification that the target entity can effectively close her lips, there should be no overall pronunciation impact, as long as the magical transformation makes accommodations with the muscles. There will still be a change in the quality of her voice, with many vowels being pronounced "wider" and the larger lower jaw dragging the timber down. Properly describing the change would require a lot of jargon, but you can simulate it by stuffing cotton balls in your upper and lower gums, like dentists do. It's kind of a "Marlon Brando" effect. Overall, even with magical muscle adjustment, it would still take a bit of retraining, during which the speaker would have a tendency to slur their words. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. Could a desert animal, with the right symbiotic microbes, avert the need to urinate by creating ammonia and having bacteria in its blood/kidneys convert it into nitrate and then back into amino acids? Or is nitrification too slow a process to ever entirely replace urination? If required, the animal can spare some of its own energy to allow the symbiotes to adapt for nitrification specifically. The animal lives is humanoid physiologically, and eats approximately the same amount of calories as modern people. The symbiotes' nitrification processes cannot be more efficient than is seen in reality, but they can do the processes more if energetically feasible [Answer] The first and obvious problem is that urination removes many toxic chemicals from the body, only two of which are ammonia or urea. At best, this plan can reduce the rate of urination by reducing how much waste needs to be removed. The second problem is that what you are describing is basically the entire nitrogen cycle taking place inside a single organism. Although this is possible, it is rather incredulous. You see, any chemical cycle uses energy. The laws of thermodynamics simply require it. This means that the organism would need less water, but more food. There are animals that make this trade-off, such as when bears enter hibernation [[1](https://www.bearbiology.org/wp-content/uploads/2017/10/Nelson_Folk_et_al_Vol_5.pdf), [2]](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0072934). However, bears can only do this because during the summer they can eat enough to build huge fat stores. If your desert had a highly predictable rainy season, then your animals copy the bears life history by 'hibernating' through the dry season and eating large amounts during the rainy season. However, that environment sounds more like a particularly harsh savanna to me than a proper desert. [Answer] Half a frame challenge: ## Use uric acid. Forming uric acid (birds, reptiles) rather then urea(mammals) is a viable option to reduce water output upon excretion. Uric acid is more expensive metabolically then urea but its plus point its much less water loss/use. The whole point of excreting urea./urea is to remove excess nitrogen that is not currently required. Presumably because every meal has excess Nitrogen, which would negate the need for recycling of Nitrogen. This is not recycling as per question, but it is avoiding urination portion with desired reduction of water use. ]
[Question] [ A powerful human king had a child with an elf princess. His life expectancy is about 70 years (human average), hers is 2000 years. The half-elf prince is expected to live for about 1000 years, more or less the average of his parents life expectancy. Years later, the prince has two children: a boy, with an elven lady; and a girl, with a mortal woman. Both of them, having a half-elf father, are gifted with a long live, but the boy lives longer than his sister, since he's the son of an elf and she's the daughter of a mere mortal. The prince becomes king, and his son becomes king after him, and so on. Their descendants have children with elves and also with humans (increasing and shortening their lifespans respectively). After generations of mixing with humans, the powerful half-elven kings lose the grace of the magical folk and become simple mortals, with an average life expectancy. What I've been doing until now is simply calculate the average and give them linear aging. But this yields certain problems... The prince's son, for example, would have a life expectancy of (1035+2000)/2 = 1517.5 years. With linear aging (0 looks 0, 1517,5 looks 70-80), this poor boy would be over 300 years old before even reaching puberty. If the same happens with pregnancy, he would be in her mother's womb for over 15 years! So, I want to know if there's a mathematical formula I can use to calculate their aging rate taking into account that they should reach puberty relatively early on their lives and lengthen or shorten their life expectancy depending on whether their mothers are elves or mortals. PD: Of course all of this is fantasy and I can give them the life expectancy I want, but I'd like to keep it more or less realistic. Also, having a "consistent framework" to work within makes me feel more confortable creating. Thank you very much! [Answer] Exponential Mathematical formula? You got it! I'm going to call this the simplest nonlinear mapping, unless someone would like to challenge me on that claim. If you have a desired life expectancy, you can map the human lifespan onto it with a power relation, of the form $\text{(human-equivalent age)}^{P} = \text{elf age}$ $P = \log\_{10}{\text{(elf life expectancy)}} / \log\_{10}{\text{(human life expectancy)}} \approx \frac{\log\_{10}{\text{elf life expectancy}}}{1.85}$ (ok fiiine you can use whatever log base you like) Neat. What's this mean? It looks to me like you already have a means of calculating the life expectancy of someone with elf blood — average that of their two parents. I don't really see any major problems with this. "My mom's life expectancy is 1000 and my dad's is 2000, so mine is 1500" does not obviously sound wrong. I'll let someone else come up with a cleverer approach, but there's not much real-world basis for elf lifespans, so we're all making stuff up here. Take the log-base-10 of that, and divide by 1.85 (the log-base-10 of about 71, which is a lowballed human life expectancy, but you can adjust). Many calculators have a button for log-base-10, or you can type "log10(1500)" into WolframAlpha and get [just around 3.18](https://www.wolframalpha.com/input?i=log10%281500%29). For our 1500-year-life-expectancy mortal, his exponent P is log10(1500)/1.85 $\approx$ 1.717. How old does an elf-blooded person need to be to look age X? They need to be X to the power of P. * Our prince's son is probably out of diapers by something like 2.51.717 = 4.8 years old. * He enters human-like adulthood at 181.717 = 143 years of age. * He might begin his physical decline soon enough, at 301.717 = 344, but he's got a long way to go. * His expected lifespan does turn out right, at 711.717 = 1509 years (alright, there were some rounding errors, close enough). * If he's lucky and makes it to the elf-blooded equivalent of a human centenarian, he'll have lived an impressive 1001.717 = 2716 years. One minor problem: the power law would imply that elves grow faster than humans before age 1, since, say, our guy looks six months old at 0.5^0.717 = 0.3 years or about four months of age. You have some options here: roll with it, or just lock the first year to human aging and then apply the power law after age 1. Lot of words for a simple concept, but I'm happy to explain further. [Answer] I'm going to give the cheat answer: There's no reason why extraordinary long life has to include an extraordinary long gestation and maturation period. Now, for a bit of science-y stuff for why I'm going to give my cheat answer: We sort of know that when you are young, certain gene pairs turn on and turn off as part of the transition from child into adulthood. We also know that certain gene-pairs turn off as we age. It's therefore entirely possible that the Elven genome has pairs that essentially keep their body in a prime state by not turning off those gene-pairs that contribute to ageing in the same way that humans do, whilst not affecting the development from Infant to adolescent to mature adult. If we go with a evolutionary explanation: Elf children still need to go from Baby to Child quickly enough in ye olden times to avoid being preyed upon by predators. If we go with the humorous evolutionary explanation, As a Parent - nothing would make me want to throw my kids out of the window more than I already do, than them staying that way for a decade. :D ]
[Question] [ I am currently designing the ecosystem for a planet within my world building project. The quick rundown is that it's tidally locked with its host star and is a very dry planet. I was thinking that one strategy for plants to gain water was through condensing water on their leaves or other surfaces. However I am unsure what shapes these plants might evolve to condense as much water as possible while being relatively efficient to make. But also keep in mind that since the sun is always in the same place plants similar to trees will evolve to make a flat wall of leaves and grass evolved to look more like leaves all pointed towards the sun. So with plants like this how might they evolve to condense water? [Answer] Koosh. Then sphere. And back. [![koosh and sphere](https://i.stack.imgur.com/Ruk5H.png)](https://i.stack.imgur.com/Ruk5H.png) To condense water your plant wants to maximize surface area while allowing airflow. A kooshball could be this. Another alternative is a ramifying structure like a tumbleweed. At night humid air flows between the branches, slows and condenses. The branches also facilitate conduction of captured droplets to the center of the plant and down to the root. The benefit of the koosh shape is that it is easily reversible. When the sun comes out, extruded branches are drawn back into the spherical body. The sphere minimizes surface area and evaporative losses. The sphere is the daytime / drytime shape. At night, cool water from the deep taproot is pumped up to again extrude the koosh arms. They are thus cool relative to the environment which facilitates condensation of passing moisture. [Answer] ## They are similar to cacti... Cacti live in hot desert climates. In dry conditions, they ideally require water only every [4-6 weeks](https://cactusenligne.ca/blogs/news/watering-indoor-cactus#:%7E:text=Water%20your%20cactus%20only%20when,the%20soil%20is%20completely%20dry.). Desert cacti can go for [up to 2 years](https://cactusway.com/how-long-can-a-cactus-survive-without-water/) without water. Three features in particular help them achieve this feat: They store water in their stems Some cacti have [thick, hollow stems](https://biocircuits.ucsd.edu/outreach/?p=737#:%7E:text=Cacti%20have%20many%20adaptations%20that,is%20stored%20in%20the%20stem.). They can store water in these stems. The stems have a waxy coating (called a cuticle) which prevents the water from evaporating. They have needle-like leaves These spines are great for keeping thirsty predators away. But they also have some added benefits: they collect water from wet air or fog, which is then transported to the stem via [trichomes](https://en.wikipedia.org/wiki/Trichome) on the epidermis. The needle-like structure also [reduces surface area](https://www.bbc.co.uk/bitesize/guides/z2jydxs/revision/9), meaning that water loss is reduced. In addition to conserving water by minimizing evaporation, the spines serve as [shade](https://www.pressconnects.com/story/news/local/2017/12/08/ask-scientist-why-does-cactus-have-needles/935726001/#:%7E:text=By%20shading%20the%20cactus%2C%20these,cooler%20and%20limits%20water%20loss.) for the plant, keeping it cooler. They have specialized roots Cacti have specialized roots which contain [parenchyma](https://www.yourindoorherbs.com/how-cactus-store-water/), collapsible water storage cells. The cells get larger as water is absorbed, and shrink when the water is released from storage for the purpose of photosynthesis. ## ...But not entirely Cacti have an additional method for conserving water which wouldn't apply to your plants. They use [CAM photosynthesis](https://www.nps.gov/arch/learn/nature/cacti.htm#:%7E:text=Cacti%20utilize%20CAM%20photosynthesis%2C%20a,moisture%20is%20lost%20through%20transpiration.), a unique process which means their pores only open to exchange gases at night. This is a time when the cactus is cooler and less water would be lost to transpiration. If your sun is tidally locked, I would assume there is no difference between day and night, so this method would not work. However, it's reasonable to assume that they'd evolve stems with storage capabilities, spine-like leaves, and roots capable of collecting large amounts of water. [Answer] A tidally locked planet would provide some interesting niches. If the sun is always in the same location then, like you said, there is some chance to derive a benefit from this. One side of the plant would be in full illumination and hotter. It would also have a shaded portion that would be cooler. The shaded portion wouldn't need any chlorophyll (or at least much less). Some plants in desserts have [little translucent windows](http://www.operationwildflower.org.za/index.php/albums/mesembs/fenestraria-rhopalophylla-subsp-aurantiaca-judd-1-9800) that they use to channel light down to lower portions of the fat leaves, that are usually underground where it is cooler. Some kind of temperature/humidity gradient could be formed by very large plants that could be used to channel warm air into cooler sections. Kind of like how termites can control the temperature and humidity of their hives by having chimneys and vents. Much of the weather on this planet is driven by the day/night, lunar and seasonal cycles. A tidally locked planet could have much less dynamic weather due to the lack of seasonal and day/night cycles but would have much more variations in location based climate. Directly facing the sun would be eternal noon (scorching) while 90 deg offset would be a constant sunrise/sunset where there would be fierce competition to rise above the plants in front. Vertical canopies would form with large bands of shade between them. ]
[Question] [ In our solar system, Europa, a moon of Jupiter, has a large and warm ocean under the icy crust. However, due to it having a rocky core and the icy crust, there is no light in the ocean. I want to make writing life, society, and technology easier by making natural light sources on Europa exist long before life evolved. In this way, life on Europa can have functional eyes and form a society like Jar Jar Binks's in Star Wars. What kind of geological change needs to happen to make a "illuminated ocean" in Europa possible? [Answer] ## [Bioluminescence](https://en.wikipedia.org/wiki/Bioluminescence) Organic things can generate light! Some creatures on Earth do this: [![Glowworm stuff in a cavern with photoshopped tourists in a small boat acting stupefied](https://i.stack.imgur.com/a6o2e.png)](https://i.stack.imgur.com/a6o2e.png) (No, not the guy in the front of the boat! The stuff on the ceiling!) All the Earth examples I'm aware of are in creatures, but there's no reason this couldn't be done by lichen or some other comparatively simple lifeform. Why might that happen? In a vast and dark ocean, emitting light makes you the center of attention. Nearby organisms will use your light as the fixed point around which they orient their activities. Some will gravitate towards your light, others will carefully hang out near the very edge of your light, still others will deliberately lurk in the darkness just outside so they can prey on the nearer lurkers. Near or far, they're all dancing to your tune. It is a primordial form of "working the refs": by emitting light, you establish the environment in which all the other players play, which makes it a lot easier for you to eke out a win in any scenario. Concretely: making yourself the hub of activity increases the likelihood that other lifeforms will collect and drop resources (including their own corpses) near you. It becomes more likely that the various "gathering" activities of other life will result in depositing those gathered resources near you. Maybe you can use those resources. Maybe those resources attract other life, driving the cycle. The winners are invariably the ones who warp the playing field to their own advantage. Like Jesse Ventura said: "win if you can, lose if you must, but always cheat." [Answer] There are a number of naturally occurring minerals that phosphoresce -- zinc sulfide, for instance, can store energy from exposure to light and will then continue to glow for some time, but can also be directly excited by UV radiation and immediately gain brightness. So, what's needed is to have a relative abundance of phosphorescent minerals (look up what was used as phosphors in fluorescent lamps or old CRT television screens) and a source of excitation for them. The excitation might be an alpha- or beta-emitting radioactive element mixed in with the phosphors, for instance (both alpha and beta area pretty readily shielded by water, especially salt water). [Answer] Cracks [![europa](https://i.stack.imgur.com/sBkR4.jpg)](https://i.stack.imgur.com/sBkR4.jpg) <https://www.nasa.gov/jpl/europas-stunning-surface> <https://space.stackexchange.com/questions/2226/what-causes-the-cracks-on-europa-to-form> The ice crust of Europa has cracks. Big old ones, small new ones. These cracks are brown presumably from accumulated tholins: carbon and nitrogen rich molecules. From underneath, a crack will be brighter than adjacent ice. It will also be a place where there will be a bloom of life because of the carbon and nitrogen rich stuff coming thru. Things that can see the light can find the resources. And then: Jar Jar! [Answer] I think it really depends on what kind of an atmosphere you want to create for your world As previous comments have suggested, you could use bioluminescence to have life. If you want to, you could use the fact that all materials emit light assuming they are above 0 Kelvin. This would create infrared light rather than visible though. You could also use some kind of radiation source or maybe even the core of the earth. Or maybe the civilisation came from another planet where there was more life ]
[Question] [ This world has a society with fairly modern technology (late 20th century or later) with a natural, reasonably healthy life span of 70+ years for people barring accidents, homicides, suicides, or a rare deadly pandemic. There is no magic and no currently impossible technology. In such a society, what kind of practices, other than a formal arbitrary retirement age, might keep the leaders of a nation, or sub-component of a nation, in a feudal, hereditary system made up mostly of young adults (say, typically in their mid-20s to early 50s with a median or mean somewhere in the middle of that range) at both the highest level of the reigning king and at each level below that down to the humblest hereditary lord with a low ranking and small fiefdom. In other words, would practices or elements of the system could cause the older generation to relinquish their positions of authority before they die of natural causes or the infirmities of old age? [Answer] Frame challenge - not plausible 1. Assuming that this is a "real" feudal system rather than relatively powerless figureheads in a democracy (eg Great Britain) then they can be equated to dictators. Ex-dictators have really low life expectancy, which is why they will do almost anything to hang onto power. So one of the absolute requirements in order to get a feudal leader to retire is an assurance that "retirement" won't be to a plot of ground six foot by three or imprisonment for actions undertaken during their reign. While extremely rare leaders may trust their successor to honour a promise to let them retire safely, this would normally require legislation of the kind that is against the spirit of this question's terms. 2. Many high-level leaders (and high-performing people in all careers) get bored in retirement. All their skills and knowledge are focused on knowing the right people and how to interact with (manipulate) them to achieve the outcomes they want, a body of experience they have built up over many years. Why would they voluntarily give that up just to let some relatively inexperienced newcomer take over, especially in the middle of the critical ongoing crisis? Given that there is always a new crisis, this becomes a never-ending justification for keeping on going. Again, the way to force handover is with legislation directly or indirectly limiting term length, which is exactly what you don't want. Further, unless the legislation is watertight then it is likely that the ex-leader will keep running things from behind the scenes by ensuring their successor is someone they can manipulate - "for their own good" if they are benevolent. 3. War leaders no longer lead from the front. Back in the old days it was important to see the banner of the king in the front ranks. Modern weapons systems make that idea idiotic today - in order to get the big picture of what is happening and make good decisions (not to mention avoiding sniper bullets), senior commanders need to be secure behind the rest of their soldiers. Younger minds may be flexible and faster, but the strategic level at which a ruler is making decisions is all about "war is an extension of politics", where political acumen is vital. (So long as they listen to the advice of their professional soldiers re what is possible and the consequences of a given course of action.) Of course, if the army is organised on feudal lines rather than being led by a professional corps of officers then there is benefit to the low-ranking feudal lords being young enough to fight, but such an organisation won't last long against a modern professional army. TL;DR the objective cannot be achieved without highly prescriptive legislation. The legislation needs to protect the ex-rulers from post-rule retribution and prevent them from trying to puppet-master the current generation of young rulers. [Answer] Competitive aristocracy Your nobility may be hereditary, and that's Ok, but your monarchy is not. A monarch is selected from a pool of eligible nobles via complex trials - and his (or her) reign has term limits. Trials may include everything that you want from a young monarch - a "spelling bee" contest or jousting - just make sure that young people would have an edge in the competition. P.S. This can not be an absolute monarchy - it has to be a constitutional one. However, the king or queen can have high level of power, similar to US president, rather than ceremonial power similar to European monarchs. [Answer] I think there would be two elements to this. First, for some reason most societies in your world have a strongly ageist culture, where anyone older than early-mid fifties, no matter how capable and popular, would be seen as over the hill and not suitable for holding any position of responsibility. This may be because the dominant religion of your world declares this to always be true. Or perhaps in your world diseases that don't kill the sufferer but lead to cognitive decline are much more common after early fifties. The second element would be, your aristocracy is in an insecure position. There are many calls for reform, either complete abolition of hereditary feudalism or at least reducing its power. The aristocratic elite must constantly project an image of being strong and capable, which in your world means being in a certain age bracket. So there is pressure on older feudal lords to abdicate in favor of the younger heir to ensure the rule of their noble family doesn't collapse altogether. [Answer] Ultimogeniture, in which the youngest heir inherits the position upon the death of the noble, has historically been pretty unusual here on Earth, but it should serve your purpose of keeping the ruling aristocracy young well-enough. [Answer] Many people do not want to give up power. Just look at the difficulty in getting older people to give up the keys to their car. The only way is to make the "retirement" more attractive than clinging to power. One way would be to make ruling be an unpaid position. All benefits come after retirement. In retirement, they get the parades, the limo rides, the special deals, and all "gifts" while ruling can only be used in retirement. ]
[Question] [ The city of Civitas Sykofantia sits on the shore of Lake Sykofantia, a high-elevation salt lake the size of Lake Superior in the US. The lake is located on the Great Pagomenos Plateau, a huge escarpment 9,500 feet above sea level, extending south from the Pagomenos Mountain Range. Due to elevation the city has a frigid subarctic climate. Climate data for Civitas Sykofantia: [![enter image description here](https://i.stack.imgur.com/5DkBY.png)](https://i.stack.imgur.com/5DkBY.png) The city has great economic wealth. It exports huge amounts of lumber, salt, osmiridium (a fictional metal), and caviar from a local sturgeon species. They export goods using flying sailboats called [startreaders](https://www.reddit.com/r/worldbuilding/comments/trs5rt/startreaders/) (use the link for context) that take off and land on the lake. The city has a population of at least 100k. How would a civilization with a late medieval/early renaissance tech level feed and hydrate such a city? [Answer] # Fish from the lake, and imported food acquired in trade. For water, cryo-desalination. Since you already said that there are fish in the lake (the sturgeon that supplies the caviar), it stands to reason that fish would be the primary protein for this city. Since the city has such great wealth, they would develop finer tastes and just import grains, vegetables, other protein, etc. that they acquire in trade for their commodities. Water can be desalted from the salty lake by freezing it. Look up Cryo-Desalination. This could be achieved using a series of successive freezing ponds, or just done on a household level. [Answer] The flying sailboats are used to transport potatoes into the city. Ancient Rome did something similar. Most of their grain came from Egypt rather than from the Hinterlands of Rome. To make imports easier just put the city on the edge of the escarpment and put the farms at the bottom. There is little horizontal distance for the ships to cover but a lot of vertical distance. As you say this is expensive but they make the money back transporting loads of tasty ore in the outgoing ships. It is a waste to send the ships home empty. So fill them with potatoes. Water is a harder issue. Rome used aquwowaducts to sent water downhill from far away. This will not work for you since your city is high up. Instead I suggest their water comes from melting nearby glaciers. To melt the water they dig their buildings a few metres into the ground. This makes them warmer than the surrounding arctic land and brings them above freezing point. Perhaps it is unrealistic to have glaciers on top of a plateau. Perhaps it is unrealistic to have ore mines on top of a plateau too. Your homework is to find out. ]
[Question] [ This is a submission for the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798). [![High Fantasy Elf](https://i.stack.imgur.com/M4K5X.jpg)](https://i.stack.imgur.com/M4K5X.jpg) Elves are a supernatural creature from Germanic cultures. Their appearances and abilities vary a lot in fiction and mythology but things they have in common are generally pointy ears, supernatural senses, and very long lifespans. There are some other aspects associated with elves like supernatural beauty and love for the forest but those are more subjective and cultural. Is there any biological reason for humanoids to evolve pointy ears. Is there also a biological way for a humanoid to have a very long lifespan or even be immune to aging? [Answer] # Yes! ### The Ears Pointed, protruding ears exist in mammal species because they are better for 360° hearing, whereas our ears are better for hearing from the front but not so much behind. So, put your elves in an environment where hearing in every direction is advantageous (e.g. natural predators). ### The Lifespan ##### What causes aging? The effects of aging are caused by cell senescence. Every time a cell undergoes mitosis, the telomeres on its DNA get shorter (telomeres are like a protective buffer segment that doesn't actually store any information). When these decay enough and the important DNA starts getting damaged, the body tells them to stop dividing. But, they do continue metabolizing, taking up resources and acting incorrectly. Sometimes they even start dividing as fast as they can, which is known as cancer. ##### Real-world examples Like having pointed ears, there are some animals that age very little, if at all. In naked mole rats, the cellular senescence mechanism doesn't just halt mitosis, it tells them to shut down and die so they can't cause any problems. This makes them more-or-less ageless, and also quite cancer-resistant. In lobsters, the body continues to generate the enzyme telomerase, which causes telomere regeneration, throughout adulthood. In other animals, telomerase production stops after the embryonic phase. So, lobsters' telomeres never decay, so their DNA stays in pristine shape and they don't age. That being said, cancer cells also rely on telomerase to divide indefinitely, so they don't get the same cancer resistance as naked mole rats. ##### Causes Something you'll want to consider though is why they live longer. There's a reason why natural selection didn't cause age prevention to evolve in most animals⁠—it doesn't help population proliferation. Elves will need to continue having children throughout their entire lives for such long lifespans to make sense from an evolutionary standpoint. Family trees might look a little weird. This could even tie into the predator presence mentioned in the section on pointed ears. Maybe they keep reproducing because they take a long time to reach adulthood where they can adequately fend for themselves. If elven parents don't stay with their offspring for that long, many will not reach maturity. Hence the need to keep making more. [Answer] Elves are humans. 1. They trim their ears to points as a coming of age ceremony. There are weirder trimmings that happen as coming of age ceremonies. Ears is not so bad. 2. They look alike, because there are not that many of them and they got pretty inbred. Luckily there were good genes starting out so they are alike looking hotties. 3. They live longer than other human groups but not crazy long. But when outsiders show up an elf will often say he is his own great grandfather and the people say "whoah!". This is where #2 comes in. Sildenafil of the Long Wood does look very much like his great grandfather, who was also named Sildenafil. And people want to believe what Sil says because of his pointy ears and smokingly hot deep violet eyes. [Answer] # Long Life Let's limit this to "Biologically Immortality:" creatures not susceptible to effects of aging, low or non-existent cancer rates, and generally meaning death comes by predator or disease. Lobsters, planarians, and jellies are given as examples of biologically immortal creatures. They are of interest to those studying [senescence](https://en.wikipedia.org/wiki/Senescence), with the hope that some of these mechanisms could yield medical applications. Another item of interest is preventing cancer. [Large mammals and other groups of mammals](https://en.wikipedia.org/wiki/Cancer) have very low rates of cancer. Once again, these are studied in the hopes of preventing and treating cancer in humans. All this to say that there is no reason, to my knowledge, that these traits could not be developed in a humanoid creature. Magic, mad science, gods, or just dumb (evolutionary) luck could result in our elves. Maybe biological immortality was achieved very early on by freak coincidence in this world, sometime in whatever stands in for the Cambrian era. Assuming it's not selected against and retained, this would be followed by a mammal ancestor that got big, solved the cancer issue, and then got smaller and humanoid. This would be different from the "live fast, die young" strategy that served the small mammals who went on to become humans. Biological immortality sounds great, there just few pressures to develop it. # Ear Shape As you may know, the [primary function](https://en.wikipedia.org/wiki/Outer_ear) of the outer ear is to focus sound into the ear canal. Larger ears generally mean better or more well directed hearing in animals, but it is unclear if a self-styled ear would help or hinder this. The larger area to receive and sense vibrations could possibly help explain the keen hearing of elves as well. An alternative to functional explanations is sexual selection. Maybe elves find pointed ears attractive and thus better mates. It isn't unusual to find [interesting bodies and displays](https://en.wikipedia.org/wiki/Sexual_selection) related to sexual selection in nature. Why not have elves talk about ear size the same way [some people talk about men's hands](https://www.webmd.com/men/news/20110705/study-penis-size-linked-to-length-of-fingers#:%7E:text=July%205%2C%202011%20%2D%2D%20The,have%20a%20longer%20penile%20length.)? Interestingly, [Williams Syndrome](https://en.wikipedia.org/wiki/Williams_syndrome) is theorized to be an origin of the idea of human-sized elves and individuals afflicted have pointier ears. However, there are plenty of undesirable effects with Williams that just won't do for a fantasy elf! This just shows that some of these traits are possible, even plausible, on a humanoid. ]
[Question] [ Could a middle-classman eqivalent afford a whellock or later flintlock pistol? How realistic would it be to give them to regular bandits with an explanation that they've gotten them from soldiers' corpses? [Answer] # Grades of Guns: We are used to the idea today that guns should be clean, efficient, and highly functional weapons that work more-or-less like they are supposed to, fire multiple shots, and generally are pretty effective. This has not always been the case. History is littered with a lot of crappy weapons using questionable engineering and generally being pretty unreliable. All the pretty guns made by good companies and sold to rich folks are in museums and private collections. But a lot of guns were simple tools of hunting, and a person who needed to hunt could get a gun that might not be pretty, safe, or reliable, but that worked. Many pistols, for example, weren't much more than a metal tube of dubious quality filled with powder and a questionable trigger mechanism (the specifics depending on the period). In the 1800's, industrial manufacturing allowed some truly lousy weapons to be made in vast quantities and very cheaply. The introduction of the percussion cap allowed some REALLY terrible engineering to still be technically a functional gun. A poor man might have a gun a hundred years out of date, but they could generally buy one, borrow one, inherit one, or steal one if it was needed. For a lot of history, the cheap model was a [matchlock](https://en.wikipedia.org/wiki/Matchlock). These were poor guns for bandits. They had to be lit on fire to use (not conducive to quick reactions) and they smoked once lit (a tell-tale you had a ready gun). They were extremely challenging to use in the rain and under damp conditions. Once a reliable and relatively simple [flintlock](https://en.wikipedia.org/wiki/Flintlock) design was perfected, the ordinary models weren't absurdly expensive. Guns were still quite valuable, however, naming them a prime thing for thieves to steal. So yes, bandits were much more likely to have flintlock guns than regular folks (and it is quite probable they would be stolen). A businessman in much of this period could buy a simple handgun. Matched sets were not uncommon, more because each was a single shot rather than because of dueling. A [wheellock](https://en.wikipedia.org/wiki/Wheellock) was actually a quite sophisticated piece of engineering based or similar to designs by Leonard Da Vinci and later designs like the flintlock were a lot cheaper than the intricate mechanics of the wheellock. They required a lot of careful maintenance. A well maintained wheellock was probably a better gun than even a flintlock, since the sparks would be generated directly on the powder and would be resistant to rain. It's not a weapon for a commoner. [![enter image description here](https://i.stack.imgur.com/a1gDx.png)](https://i.stack.imgur.com/a1gDx.png) This gun was used by postal carriers, and would be the kind of relatively cheap weapon affordable to more normal folk. [![enter image description here](https://i.stack.imgur.com/y3I1T.png)](https://i.stack.imgur.com/y3I1T.png) This second gun was a weapon issued to French officers, and is likely similar to the kind of gun one might steal off of soldiers. Common riflemen were unlikely to own pistols, and soldiers were at many times among the lowest paid people in society. A stolen pistol would be an officer's weapon. [![enter image description here](https://i.stack.imgur.com/Ary2K.png)](https://i.stack.imgur.com/Ary2K.png) Wheellock pistols were the first readily useable concealable pistols, and they would be highly prized by highwaymen, but the maintenance and cost would make them tricky in this role. They were outlawed at times due to their usefulness in assassinations. [Answer] Smooth bore flintlocks are not terribly difficult for most blacksmiths to make. Forge welded barrels, usually a screw in breech plug. For the lock mechanism a simply V shaped spring. The spring steel might be one of the more difficult materials to make. The best barrels should be drilled using long drill bits. For rifled barrels more work is needed to do the rifling. There is a lot of filing work. It is time consuming which is why early firearms were expensive. The industrial revolution with machining tools drill presses, lathes, milling machines and shapers greatly reduce the cost of making weapons. This is one of the factors responsible for an increase in the number of firearms. They went from handcrafted master pieces taking weeks of labor to mass produced item that could be completed in a few hours. ]
[Question] [ In my book series, there is this lake called Lake Pheron. Lake Pheron's surface is located about 2,200 feet above sea level in a mostly flat, inland area called the Tangolian Desert. This desert is bounded by mountain ranges only a couple hundred miles at most from the lake to the north, west, and south, but the desert goes on for another almost 2,000 miles to the east and 3,000 to the southeast before transitioning to the Tangolian steppe. The area of the Tangolian Desert where Lake Pheron is has a climate most similar to the Sonoran Desert around Phoenix, and the desert generally gets cooler and drier the further southeast you go, only getting slightly wetter again near the edge of the Tangolian steppe. Lake Pheron is absolutely huge, around the size and depth of Lake Superior in the United States, and supplies the otherwise desert area immediately around it with fresh water for drinking, irrigation, and other uses, making the otherwise desolate wasteland one of the agricultural powerhouses of the empire that controls this area (the Aurean Dominate). Lake Pheron is fed from a massive underground aquifer that sits around the large depression the lake occupies. Lake Pheron is also one of the sources of the massive Pheron River system, both the longest and widest river on the entire Planet of Aurea. The most important of these rivers, the Pheron River, originates from the icy peaks of the Monsaltu Range that bounds the Tangolian Desert to the north, and flows southwest through the desert for a couple hundred miles before a tributary of overflow from Lake Pheron joins it, greatly increasing its size. The river then flows south and southeast past the lake, picking up many tributaries from the Imbreus Mountains bounding the desert to the south, before turning east and flowing through the scorching heat of the Tangolian Desert for around 2,000 miles before converging with the Hsia River in the Tangolian steppe. The Pheron River then flows another 2,000 miles through the remaining steppe, forests, and grasslands before emptying out into the ocean in a gigantic delta. The Hsia River, which I mentioned above, has its origins in the Great Eastern Mountains, a slightly smaller mountain range a hundred miles or so to the northeast of Lake Pheron. Once it comes down from the mountains and into the desert, it flows roughly parallel to the Pheron River without much input from other sources before picking up the Gyumala, a large tributary, at the edge of the Tangolian steppe before converging with the Pheron River about 100 miles downstream. Both the Pheron and Hsia Rivers are about as wide and deep as the Amazon for most of their length and don't pass through any super steep terrain until you get far enough upriver to get close to their mountain sources, so the entire system including Lake Pheron is navigable by ocean-going ships, and the Pheron River System has evolved its own freshwater versions of many marine creatures, most notably tuna, penguins, sea lions, fur seals, true seals, sharks, dolphins, and what we would call Japanese spider crabs, all of which can be found as far upstream as Lake Pheron and beyond. Is it plausible for such a large freshwater river and lake system to develop in a hot desert environment such as this, or would the water evaporate or salinate before this could happen? [![Map of the Tangolian Desert (yellow is desert, lines are rivers, the dotted line is a provincial boundary of the Aurean Dominate, the purple areas are mountain ranges, orange/red areas are steppes, and Mt. Pontus is Mt. Monsaltu now because this clunky map is outdated but it's what I had to go with because it's the only one I had of this area that shows rivers)](https://i.stack.imgur.com/R8fDP.jpg)](https://i.stack.imgur.com/R8fDP.jpg) Map of the Tangolian Desert and surrounding areas (yellow is desert, lines are rivers, the dotted line is a provincial boundary of the Aurean Dominate, the purple areas are mountain ranges, orange/red areas are steppes, and Mt. Pontus is Mt. Monsaltu now because this clunky map is outdated but it's what I had to go with because it's the only one I had of this area that shows rivers) [Answer] # Yes, this happens all the time Here is a possible conversation explaining it in your book: * Teacher: Why is Tangolia a desert? * Student: Because it doesn't get any rain. * Teacher: Yes, but why doesn't it get any rain? * Student: I don't know, it just doesn't. * Teacher: Rainstorms form over the ocean where the water evaporates and forms clouds, when those clouds cool, the water falls as rain. The clouds may cool for many reasons, but the one that makes Tangolia a desert is the mountains. When the clouds pass over the mountains, they need to rise, and when the clouds rise they cool. This causes most of the water to fall on the mountains as rain or snow, so it never reaches Tangolia. However, we're fortunate that we live near the rivers that come from these mountains, otherwise we wouldn't have any water. [Answer] In real world, [Rift Valley lakes](https://Rift%20Valley%20lakes) in East Africa can give an idea on how a lake and a river system can be formed in a desert. One of them is Lake Turkana which is the largest permanent desert lake in the world, however it is an alkaline lake. On the other hand, there are two freshwater desert lakes in the same series of lakes, Lake Baringo and Lake Naivasha. They are called rift lakes. A rift lake is formed: > > as a result of subsidence related to movement on faults within a rift zone, an area of extensional tectonics in the continental crust. They are often found within rift valleys and may be very deep. - [Wikipedia](https://en.wikipedia.org/wiki/Rift_lake) > > > Here is a cross-section of the East African Rift Valley: [![enter image description here](https://i.stack.imgur.com/L58lwl.jpg)](https://i.stack.imgur.com/L58lwl.jpg) What makes Lake Baringo and Lake Naivasha freshwater is that the lake water seeps into the faulted volcanic bedrock, taking the salts with it. Other reasons can be less rate of evaporation and more rainfall. However, you can possibly have a larger freshwater desert lake in a bigger rift, and with surface outlets where salt deposits are carried away. ]
[Question] [ The Areans are a human-like species that have become wholly dependent on their technology. Most notably is their circulatory system They float in a blood-like liquid, and instead of lungs their pulmonary vessels simply take in and excrete this fluid to the environment. The liquids are in constant flow and kept oxygenated, stocked with nutrients, and other functions needed to keep the Areans alive Could such a communal circulation sustain the Areans? Or are there some unavoidable issues that would make it impossible? [Answer] I will have to answer with what @elemtilas predicted: "Could a system like this be made" because you have said that it already happened through handwavium. I will begin with some conceptual issues with the framing of this question, but in the end I hope the underlying problem asked will find an answer. Bear with me. This question treats human blood as if it only carries oxygen to cells, but this is not true. What your system is missing is, well, a lot. But mostly, it is missing the very concept of circulation, which requires pressure differentials, which require containment. In other words, you can not do away with a closed system and a pump, and still use the word "circulation." Veins are controlled by the nervous system to target areas of the body which need nutrients, antibodies, oxygen, hormones, etc. They also target areas where excess waste has collected, such as dead cells, carbon dioxide, toxins, etc. If you remove the closed system, you take away the nervous system's only tool for getting these provisions to; and removing these wastes from, the areas of your body which need attention. The closed system also is the only way the oxygen can possibly reach human body cells, because once open to the air, the oxygen will be taken up and absorbed. Only be being contained in veins can the hemoglobin get oxygen to the cells as oxygen. If you design your fluid so it does not oxidize, then you have also designed it so a human cell can not oxidize with it, and killed all human cells. The thing in the fluid will not be made of human cells. A circulatory system must be a circuit, which is in the very definition of it. A free-flowing fluid would not sustain any organism which could still be considered "human;" anything adapted to that environment would look, behave, and function in a way that would be unrecognizable as "human." If the problem in the question is simply one of respiration, as it seems to be, and you do not want to concern the plot with buggering up all the other circulatory functions, then ## the fluid you are speaking of has already been found. It is called [perfluorocarbon](https://engineering.cmu.edu/news-events/news/2017/11/20-nelson-perfluorocarbon.html) ![](https://engineering.cmu.edu/_files/images/news/2017/1120-nelson-infographic.png) This is technology we are already using to replace human respiration in people who cannot use their lungs for one reason or another. It seems to fit the technical requirements of your problem, from the perspective of providing oxygen to the body. [Answer] #### Obviously You've already established two critical facts, namely: * The Areans are a human-like species that have become wholly dependent on their technology. * Most notably is their circulatory system You then tell us what this technology does: * They float in a blood-like liquid, and instead of lungs their pulmonary vessels simply take in and excrete this fluid to the environment. The liquids are in constant flow and kept oxygenated, stocked with nutrients, and other functions needed to keep the Areans alive The only logical answer to your query is 'yes' because you just told us that this is how they live! In other words, since this is how they actually live, there are no "unavoidable issues that would make it impossible!" I think the likely follow-ups might be something like "Could a species with specific attributes X, Y, and Z come up with a viable technology that does M"; and "Given technology M and a species with attributes X, Y, and Z, how does the technology work?" [Answer] No. Consider the following points Germs and Bacteria The liquid is full of nutrients. So germs and bacteria will grow (like in fruit juice or even in stagnant fresh water). Sick or Dead Humanoids Any sick humanoid will secret germs and bacteria thus spreading the disease. When a humanoid dies, its body will be absorbed by the liquid. If it was already sick, the sickness will spread. Nutrient requirements Same nutrients don't benefit everyone. Different nutrients are required * at different ages * under different health conditions * under different working conditions * at different temperatures Multiple species If humanoids could evolve in the liquid, then different other kinds of species may evolve in the same liquid. All different species could contaminate the liquid. [Answer] No The combination of having a human-like species and a communal blood supply are incompatible. The blood a person uses has too many "personalised" components to allow for a one-size-fits-all supply. Nutrients need to be tailored to individual energy and growth requirements that vary radically over time. The nutrient composition of the blood of a new-born baby, a toddler, a youth just hitting puberty and a mature adult will be very different. Even within those groups, the nutrients required by an athlete and an office worker will be very different. You may posit a very enriched nutrient content for everyone and bodies with each individual cell being sufficiently "smart" to only take the nutrients it requires, but a creature like that is not remotely human. Secondly, a humanoid body pattern does not make sense for a species that need to spend most of their time floating in their blood-like substance. The human body plan is optimised for walking and running long distances, climbing when required, spotting threats and opportunities at a wide range of distances, throwing objects accurately and general tool use. The tool use is the only useful ability for a species living in a (probably opaque) liquid that they can only leave for as long as they can hold their breath. The arms might work, but the legs can definitely be traded in to get a useful tail and the head will need to change considerably to facilitate sonar. (How to generate sounds for communications and sonar in the absence of lungs is left undefined.) Note 1 - all of these problems disappear if the species simply has single-user devices providing the blood supply. The question is why build all these functions into an external device when the lungs, stomach, intestines and other organs could handle these functions internally. Note 2 - I have deliberately omitted any discussion of waste removal, filtering and cross-contamination. All the air-breathing animals on Earth breathe a communal atmosphere that we are each expelling waste products, bacteria and viruses into constantly. Similarly, aquatic animals are expelling waste products into communal water including fecal matter. Given this situation, these are clearly solvable (or at least species-survivable) problems even without high technology. A separate excretory system to handle waste without contaminating the "blood" supply would probably be a good idea though. ]
[Question] [ There's some pattern within our solar system and many others as well such as the planetary orbits lay within some gradually increasing distances. I assume they could be spread less regularly (looking at SS because extrasolars are still eclipsed by many instrumental errors and no one from my neighborhood was there himself and seen their complete picture) but natural forces kept them away from each other. Maybe at the creation moment like one stone creates circles on water - I'm not sure, but I would like to know is there any point where 2 planets having very tightly planned circular orbits (say 1AU and 1.01 AU) from which their orbits would be not stable because when planet A closing up to B it suddenly got bigger acceleration from her than the Sun. I assume there's the case but how to calculate this point if my conclusion is good? When I take gravitational force equation like this: ``` U = {'G': 6.6743e-11, 'jm': 1.89813e+27, 'sm': 1.98847e+30, 'em': 5.9722e+24, 'au': 1.495978707e+11, 'mm': 7.34767309e+22} Fsun = U['G']U['sm']U['em']/U['au']*2 Fmoon = U['G']U['mm']U['em']/3840000002 print(Fsun, Fmoon, Fsun/Fmoon) ``` and get `3.5416715752424943e+22 1.986220425457726e+20 178.31211127668843` I see that Sun is still almost 200 times stronger to attract the Earth than the Moon. I assume it's the case that Moon doesn't do his orbit alone around Sun but together with Earth. But what if for example Earth (or earth-like body) overtake a planet from AU=1.01 and meet conditions to bind together with that body? Is it the right equation to decide whether if the gravity of `Fbody` were stronger than `Fsun` then those orbit wouldn't be separated no more? Is it right approach? Or maybe it's much more complicated? How close should pass a Jupyter some Earth planet to disturb the latter orbit within a Sun's system? \\* EDIT \\ The 3-body problem it appears to be. Found some nice simulation imaging what happens when 500x mass Jupyter orbits the same star. [3 body movement](https://github.com/zaman13/Restricted-Three-Body-Problem-Gravitational-System/blob/master/sample_output_1.gif) taken from [`https://github.com/zaman13/Three-Body-Problem-Gravitational-System`] [Answer] When two objects orbit a central body, the closer their orbits pass to one-another's, the more likely they are to become co-orbital, collide, or for one to be ejected from the system. What will happen is dependent upon a great many factors, including the masses of the bodies involved. Given that this is a potentially chaotic situation, there is no easy way to say which will occur other than to simulate the system and see what happens. [Answer] There are a few reasonably plausible ways to design a fictional solar system with planetary orbits quite close together. Part One: Crazy Co-orbitals. Epimetheus, a moon of Saturn, orbits the center of Saturn with a semi-major axis of 151,410 kilometers, plus or minus 10 kilometers. Janus, another moon of Saturn, orbits the center of Saturn with a semi-major axis of 151,460 kilometers, plus or minus 10 kilometers. That is a difference of approximately 30 to 70 kilometers. Epimetheus has dimensions of about 129.8 by 114 by 106.2 kilometers. Janus has dimensions of about 203 by 185 by 152.6 kilometers. <https://en.wikipedia.org/wiki/Epimetheus_(moon)> <https://en.wikipedia.org/wiki/Janus_(moon)> So the radii of the two moons in their orbits largely overlap, and when the inner moon Epimetheus catches up with Janus they should collide and destroy each other. But that doesn't happen to those co-orrbital moons. > > Janus's orbit is co-orbital with that of Epimetheus. Janus's mean orbital radius from Saturn was, as of 2006, only 50 km less than that of Epimetheus, a distance smaller than either moon's mean radius. In accordance with Kepler's laws of planetary motion, the closer orbit is completed more quickly. Because of the small difference it is completed in only about 30 seconds less. Each day, the inner moon is an additional 0.25° farther around Saturn than the outer moon. As the inner moon catches up to the outer moon, their mutual gravitational attraction increases the inner moon's momentum and decreases that of the outer moon. This added momentum means that the inner moon's distance from Saturn and orbital period are increased, and the outer moon's are decreased. The timing and magnitude of the momentum exchange is such that the moons effectively swap orbits, never approaching closer than about 10,000 km. At each encounter Janus's orbital radius changes by ~20 km and Epimetheus's by ~80 km: Janus's orbit is less affected because it is four times as massive as Epimetheus. The exchange takes place close to every four years; the last close approaches occurred in January 2006,[15] 2010, 2014, and 2018, and the next in 2022. This is the only such orbital configuration known in the Solar System.[16] > > > <https://en.wikipedia.org/wiki/Janus_(moon)> And it seems possible that the co-orbital status of Janus and Epithemeus, with them switching orbits appoximately every four years, may have existed for tens of millions or hundreds of millions of years. So a science fiction writer might consider designing a solar system where two planets orbit the star in such an orbit about a thousand times larger with about 50,000 kilometers betweeen the two planetary orbits. And if they have a program that can run orbital similations, they might possibly determine how long such an orbital configuration would be stable for. Of course, the orbital periods of the two planets around the star would be about one Earth year long, and it would take thousands of such orbits for the inner planet to catch up with the outer planet and for them to switch orbits. So in the millennia between such events, a civilization could arise on one of the planets and develop astronomy and discover that the planets orbited around their star, and notice that the inner planet was catching up with the other planet. And if their math wasn't up to calculating what would happen, there might be widespread fear that the planets would collide or that one would be ejected from its orbit. Part Two: Forbidden Zones. Stephen H. Dole, in Habitable Planets for Man, 1964, discusses the spacing of the planets in our solar system among many other factors involved with planetary habitability. <https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf> On pages 48 to 52 Dole discusses the forbidden regions around the orbits of planets. The size of the forbidden region of a planet is calculated from the planet's mass, the mass of the star, and the semi-major axis of the planet's orbit. Within the forbidden region, smaller objects can not have stable orbits and so can not clump together to form planets. According to Dole's calculation, about half of the Solar System is within the forbitten zones of various planets. Thus at most about twice as many planets of similar size could exist within that distance of the Sun. Of course other planet could have stable orbits farther out than the known planets. I note that small changes in the mass of main sequence stars cause greater changes in their luminosity. If star A is one percent more or less massive than star B, its luminosity will me more than an one percent higher or lower than the luminosity of star B. So a planet in the habitable zone of a more massive and luminous star will be relatively farther out in the star's gravity field than a planet in the habitable zone of a less massive star. Thus the gravity of the planet should be stronger relative to the gravity of the star at its orbital distance, and the planet should ahve a larger forbidden region. And a planet in the habitable zone of a less massive and luminous star should orbit deeper within the gravity of the star and thus the gravity of the star will be stronger relative to the planet's gravity, and that should make the planet's forbidden region smaller. Or maybe it goes the other way around. I'm not sure. The famous TRAPPIST-1 star system has 7 planets orbiting very close to a small dim star, TRAPPIST-1. The planetary obits thus have semi-major axis with small differences between them, hundreds of thousands of kilometers instead of tens or hundreds of millions. > > All the planets would be visible from each other and would in many cases appear larger than the Moon in the sky of Earth[68] > > > <https://en.wikipedia.org/wiki/TRAPPIST-1#Skies_and_impact_of_stellar_light> > > Three or four[42] planets – e, f, and g[129] or d, e, and f – are located inside the habitable zone.[59][x] > > > <https://en.wikipedia.org/wiki/TRAPPIST-1#Habitable_zone> Because they are so close to their star, all the TRAPPIST-1 planets are probably tidally locked to it, and it is uncertain whether tidally locked planets can have life. TRAPPIST-1 is believed to be older than the Sun, so the planets should have had their present orbits for billions of years. The Kepler-36 system has the smallest known ratio between planetary orbits. <https://en.wikipedia.org/wiki/List_of_exoplanet_extremes#Orbital_characteristics> Kepler-36 b has an orbital semi-major axis of 0.1153 AU,and Kepler-36 c has an orbital Semi-major axis of 0.1283 AU, a difference of 0.013 AU or 1,944,772.3 kilometers. The ratio between the semi-major axis of the orbits is 1.1127493. <https://en.wikipedia.org/wiki/Kepler-36> If a planet orbited its star at a distance of 1,000,000 kilometers, a planet orbiting 1.1127493 times as far out would be at a distance of 1,112,749.3 kilometers, 112,749.3 kilometers farther. If a planet orbited its star at a distance of 1,000,000,000 kilometers, a planet orbiting 1.1127493 times as far out would be at a distance of 1,112,749,300 kilometers, 112,749,300 kilometers farther. So one can imagine a solar system with a habitable planet at 0.898 AU, another at 1 AU, another at 1.1127493 AU, a fourth at 1.238211 AU, a fifth at 1.377818 Au, and so on. Though I don't know if such close orbits actually would be stable. And I don't know how well those close orbits in the TRAPPIST-1 and Kepler-36 system agree with Dole's calculations of planetary forbidden regions. Part Three: Trojan Planets. One possible planetary arrangement would be for two planets to share the same orbit around their star, separated by 60d egrees, a trojan orbit. HOwever, all know trojan orbits in our solar system involve objects with vast mass differences between them. For example, the mass of the Sun is about 330,000 times the mass of Earth, and thus about 6,000,000 times the mass of Mercury, and about 1,038.3889 times the mass of Jupiter. The largest asteroid in a trojan orbit is 624 Hektor, about 200 kilometers wide, about 0.0157 the diameter of Earth, and thus about 0.0000038 the volume of earth, and presumably having less than 0.0000038 the mass of Earth, which would be less than 0.000000011 the mass of jupiter. > > As a rule of thumb, the system is likely to be long-lived if m1 > 100m2 > 10,000m3 (in which m1, m2, and m3 are the masses of the star, planet, and trojan). > > > <https://en.wikipedia.org/wiki/Trojan_(celestial_body)> The dividing line between planets and brown dwarfs is about 13 Jupiter masses or about 4,131.4 Earth masses. A system with a highest mass planet and an Earth mass planet would be unlikely to be stable. Similarly a system where the larger planet was Earth mass would probably not be stable unless the smaller object had less than 0.0001 Earth mass. And the smallest gravitationally rounded bodies in the solar system that could be called planets and not asteroids or other minor bodies have mass around 0.0001 Earth mass. The mass range for habitable planets would probably be only about 10 or 100, certainly not enough for a larger planet and its smaller trojan planet to both be habitable. But something even better than trojan obits has been proposed. Part Four: Co-orbital Rings. Astrophysicist Sean Raymond in his PlanetPlanet blog has a section devoted to designing imaginary solar systems with as many planets, preferably habitable, as possible. In "The Ultimate Retrograde Solar System", Raymond found a paper by Smith and lisseur saying that if alternate planetary orbits were in opposite directions, planets could be packed closer together with stable orbits than if they all orbited in the same direction. <https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/> <https://ui.adsabs.harvard.edu/abs/2009Icar..201..381S/abstract> Raymond said that about four planets could orbit the Sun in the habitable zone if they all orbited in the same direction, but about eight could orbit the sun if they orbited in alternating directions. But Raymond warns science fiction writers: > > With the Retrograde Ultimate Solar System we are now swimming in impossible waters. Two planets can end up orbiting the same star in opposite directions, but only if their orbits are widely separated. I don’t know of any way that nature could produce a system of tightly-packed planets with each set of planets orbiting in the exact opposite direction of its immediate neighbors. > > > This means that the Ultimate Retrograde Solar System would have to be engineered. Created on purpose by some very intelligent and powerful beings. > > > Such a solar system with closely packed orbits alternating between prograde and retrograde would have to be artificial, and not natural in your story. Characters who know much about planetary formation would have to know that system was artificial. The good part is coming. in "The Ultimate Engineered Solar System" Raymond references another paper by Smith and Lissauer. <https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/> <https://ui.adsabs.harvard.edu/abs/2010CeMDA.107..487S/abstract> Smith and Lissauer show that a ring of co-orbital planets can be stable, if the planets all have the same mass and are all equally spaced along the orbit. So Raymond designed a system with 42 Earth mass planets sharing the same orbit 1 AU equally spaced. Since an orbit with a radius of 1 AU would have a circumference of about 1,022,022,733 kilometers, 42 equally spaced planets would be spaced about 24,333,874.6 kilometers apart on the orbit. Then Raymond designed a system with six rings of 42 Earths apiece within the Sun's habitable zone, for a total of 252 Earth like planets. If the planets were smaller, with about 0.1 times the mass of Earth (about the mass of Mars) there could be 13 rings of 89 such planets each for a total of 1,157 mars like planets in the habitable zone. Then Raymond designs a system with planets with half of Earth's mass, and so 52 planets in each ring, and with the rings of planets alternating their orbital directions. That gives eight orbits with 52 planets per ring, a total of 416 planets. But of course such a system could never form naturally. > > I can only think of one way our 416-planet system could form. It must have been purposely engineered by a super-intelligent advanced civilization. I’m calling it the Ultimate Engineered Solar System. > > > We can make such a system millions and billions and trillions of times more plausible by making all the planetary rings orbiting in the same direction, which will reduce the number of rings and the total number of planets. So that would make the system much more likely to form naturally. But you would probably still have to search millions and billions and trillions and quadrillions of star systems to find one like that which had formed naturally. So any such star system in fiction would have been made artificially by an advanced civilization. ]
[Question] [ I have a class of animals in my world that have a bit of an unusual method of reproduction. Members of this class produce pod-like eggs. These pods are buried in the ground to incubate until the first rainfall, after which they begin to develop their own root system or hijack the roots of neighboring plants. These pods continue to develop the animal inside until it reaches full size, at which point the animal will claw its way to the surface and emerge. While I am less concerned with the realism of the method, I am wondering what circumstances would allow for this method to become as prevalent as mammalian reproduction is on Earth. [Answer] What you describe is a super common method of insect reproduction. <https://entomology.unl.edu/turfent/documnts/wgmanagement> [![After hatching from eggs, white grubs begin feeding on the roots and underground stems of turfgrasses. The first evidence of injury is localized patches of pale, discolored and dying grass displaying symptoms of moisture stress...Turf in such areas will have a spongy feel under foot and can be easily lifted from the soil surface or rolled like a carpet, revealing the C-shaped white grubs underneath.](https://i.stack.imgur.com/N5ix9.jpg)](https://i.stack.imgur.com/N5ix9.jpg) Developing their own roots is not a doable deal because there is no energy produced - just nutrients taken up. "Hijacking" existing roots (by eating them or drinking the sap) is totally workable and it works for lots of insects. Mammals and reptiles exist because of their special systems to deal with immature animals. Those systems would be disadvantageous for a circumstance where immatures lived underground and ate roots. It seems less of a stretch for amphibians. What they do is already close. [![tadpole eating](https://i.stack.imgur.com/BFE50m.jpg)](https://i.stack.imgur.com/BFE50m.jpg) Immature amphibians are vegetarian. They then metamorphose and emerge from the water. That is roughly what you are having your creatures do. Subterranean vegetarian immature tadpole equivalents will eat roots until maturity then leave the ground just as conventional amphibians leave the water. Underground it is safe from predators. In circumstances of lots of plants and an amenable subterranean habitat I can imagine amphibians could do this. In fact it seems so workable I bet in the tropics some do exactly this. Let me dig around some... --- That didn't take long. [Biologists Have Discovered Underground, Burrowing Tadpoles](https://gizmodo.com/biologists-have-discovered-underground-burrowing-tadpo-1768079252) [Answer] Some plants might find it useful and develop a form of symbiosis, so that both the animal and the plant gets benefit out if it. Then, in a world with high infant mortality, this method would allow for large numbers of prole to be produced with same investment by the parents and ensure some of them reached reproductive age. [Answer] The tricky part for me is the roots. Placing eggs underground is perfectly normal, so I don't think it needs justification. What are the roots for? In plants, roots serve several roles: They are anchors that hold the plant to the ground. They gather water from the environment. They gather secondary nutrients (particularly nitrogen) from the environment. They have a few other roles, but these are the main ones. In particular, roots are not about "feeding", in the sense of gathering energy (and "plant food" isn't food for plants) So what could be the reason for your pods to have roots? You might want to anchor the pod if it liable to be dislodged. But if the pod has no leaves and branches, this doesn't seem to be a likely concern. You might want to collect water or nutrients if they are somehow scarce. But why is it not easier for the mother to simply put some of her water and a supply of nutrients in the pod? She'll be putting calorific nutrients in the pod to feed the embryo anyway. Unless she isn't... If the reason to have roots is to grow plants, perhaps the animal isn't laying eggs, she is planting seeds... Perhaps her strategy is to plant seeds that grow into plants, that grow roots, and branches and leaves to photosynthesise and grow as plants and which then produce in alternate generations animals. This looks a little like the alternation of generations that is found in Ferns and cycads, but taken to an extreme: --- So the animals are gametophytes. They are formed entirely of gametes, cells with only one copy of the genetic material (unlike human cells that have two copies of each chromosome). They mate and the female produces "pods/seeds" that she plants, or scatters (she might produce only a few or many millions). From these seeds, a sporophyte grows. It is rooted to the ground, it looks like a plant and has no brain. The sporophyte, when it is mature, undergoes meiosis producing eggs (that may be held within its trunk, for example, or scattered) the eggs develop and from the eggs emerge the gametophyte animal that must seek a mate, and may be carnivorous or herbivorous. Perhaps eating the very same sporophyte plants of the alternate generation. Why did this complex form of reproduction develop? It is a "best of both worlds" strategy. You are a plant for half the time and an animal for the other half. It is hardly less complex than other ways of reproducing - think "placental mammals" for a truly ridiculously complex reproductive cycle. Some cycads already do this. They produce sperms cells that are tiny haploid animals that actively swim. They are only 0.5mm long, but you can take this model of reproduction to its artistic conclusion and get full size haploid animals. [Answer] ### Parallels with known animals The basic description reads similar to how many insects place their eggs. Which is placement of eggs in/on food source. Which upon hatching they start consuming. I would say among creatures that lay eggs, that have low parental care this is a very common thing. ### Differences to known animals The unusual thing for this question is upon hatching/activation the embryo acquires resources via vegetational absorption rather then eating and digesting. Having two systems of nutrient acquisition is going to be costly. Another way of describing it is these creatures go through a stage of being parasites. This would be the major rational for this method of living. Taking resources from another life would compensate for the costs. ### Plausibility of prevalence So essentially external implantation of embryos that then parasite resources until sufficient stage of growth for independent living. This would become prevalent if there are sufficient hosts to parasitize, and the hosts do not have sufficient resources to keep them away. I see this as competitively viable. I don't see it dominating as other systems such as simply lay eggs that hatch and eat are simpler thus have an edge in many cases. ]
[Question] [ (I have edited this post for clarification) Context I am currently designing a world where there is a species of werewolf-like beings. They call themselves the Amali and live side by side with humans. The two sides are friendly and even have children with one another, the children being just as likely to be human or Amali. In this world, life is generally good, but there is no electricity and few machines. Here is a list of traits the Amali possess: 1. During times of high emotion, they turn into massive wolf-beasts. While feeling intense emotions, the Amali become beasts more than twice the height of a human. Their jaws and claws are strong enough to rip apart bone. That makes them dangerous, as they are difficult to stop in this form. 2. Even in their human forms, they are far more powerful and faster than humans. Even the weakest Amali has the strength of ten men. They are faster than humans and have better reflexes. One stray punch from an Amali could easily injure a human. 3. Amali are constantly overwhelmed by their senses. Amali smell, hearing, and taste are intense compared to a human. With sight and feeling being roughly average. Also, their tails and ears are extremely sensitive to being touched. Even in their human forms, they maintain their pointed ears and long fluffy tails. The Question What is one cultural change a society of mostly humans would inevitably have to make to safely live alongside a class of Amali, even though the latter class is stronger, faster, and have keener senses than humans? In other words, what is one major cultural or societal change that would allow the two sides to coexist peacefully? I am looking for one clear solution that: -Is as humane and painless for both sides as possible. -Takes into account all three aspects of the Amali -Naturally incorporates the two sides, human and Amali, into one cohesive and mutually beneficial society. I am not looking for a solution that: -Actively hurts either the Amali or the humans -Endorses enmity or dehumanization of either the Amali or the humans. -Does not consider the complications Amali powers might bring on a society of many humans. [Answer] Humans are already pretty scary. We have cops. There have long been big dudes in society. Dudes much bigger than me. They may have big beards, these dudes and sometimes they look at people much smaller than them and you can't tell what they are thinking. Maybe violent thoughts. I heard one of these very large dudes got violent and threw people around. They can be prone to rage I am told. Probably when they get into the liquor. I, a medium sized dude, am very polite and calm around these big dudes and so far I have not had any trouble from one. But if there is trouble, fortunately society has other big dudes and some medium sized dudes and dudettes who have regular jobs keeping order. They are the police. If one of these scary big dudes starts stomping around and snorting, you can call the police. In some cities they shoot the scary dude. In other cities they might beat him into submission, or if police persons are equally big, tackle him. Sometimes the police will try to talk an enraged dude down and with a little luck that could work. Scary big people is nothing that human society has not dealt with. The fact that they are also hairy and sensitive does not make them harder to cope with. [Answer] Without modification to how you've designed the Amali, I'd say the only way that they can live comfortably alongside humans - with them both as free equals - is by intense social codes. Maybe in the past there was awful misuse of the Amali's wolf form, and thus society has built up for the Amali in the wake of this prioritizing virtues like self control, and calmness. Another route might be interbreeding between humans and the Amali - the effect of diluting the gene pool has lessened some of the harsher effects - perhaps after a great deal of time of intermingling, the larger part of the Amali are partially removed from their ancestors - they will turn into wolf creatures, and be more angered and strong in this state, but they are able to control themselves. Perhaps the humans are extremely afraid of Amali. This leads them to walk on eggshells in every interaction with them. There is the alternate route from all this that one race subjugates the other - but I think that there are many other routes aside from that, and ones that still provide a great deal of interesting stories to tell. Maybe of an Amali that is more genetically "pure" and hence is more vicious in their transformation - they are extremely self conscious and receive much prejudice for their status. Now, as far as societal policies to better accommodate the Amali - I imagine the biggest one is having a specific subset of the police that is focused only on taking control of those who are transformed and enraged. Maybe they search out Amali that are well restrained and train them to control their transformations well in a safe environment. Heavy fines might be imposed on those who cause destruction after transforming - this might keep the Amali in check out of fear from their own legal and government systems. Again, opportunities for stories, where an Amali mother could feel extreme burden at her inability to control herself, and thus endangering the welfare of her family. On the technological side, perhaps there are certain herbs and medicines designed to pacify those prone to transforming. Even in a pre industrial world there would likely be many such things. Alcohol unfortunately, might be one of them. As for things like you mentioned, chairs allowing for tails - do the Amali have features like wolf tails and ears when not transformed? If so, I don't see this being especially difficult. Many chairs in our world already have a gap at the back. Clothing would have to be tailored specifically for Amali to allow their tails and ears to poke through. Nothing really too difficult. [Answer] Lets compare it to a real life example. Elephants. # Will they hurt you randomly? If they want to. Large animals with immense strength can happily be used around children. Muscular strength isn't something you're forced to use. An elephant can be gentle and friendly and loving as much as it can brutally crush their enemies. As such, the only ones that will be allowed nearby are the ones that have a friendly personality. If they are trusted they'll be allowed to be close. If they murder someone it's likely intentional. Just as you can be gentle and friendly to an ant, enough to stroke it if you want, even a super strong wolfman can be gentle and friendly to humans if they want. Ones who were unfriendly could easily be captured and killed with spears and sense bombs, either loud noises or powerful scents. You would likely have some specialists to do this in most villages, specialist werewolf death and disabling squads. # You can sit on normal chairs with tails, by sitting on them sideways or backwards. [![enter image description here](https://i.stack.imgur.com/041fX.jpg)](https://i.stack.imgur.com/041fX.jpg) You can also curl your tail into your lap, or wrap it around the chair leg. If the chair was made to accomodate them, it may have a hole in the back. # Some sensory adaptions would be needed. There would probably be a big push by the Amali to keep the place clean. The latrines would be far away, they would work hard to make sure fresh water was nearby to allow cleaning. There would be food made for Amali, with gentler tastes. Some brave Amali would no doubt try human food, and run away with burnt mouths. The big accomodation you need is an equalizer between Amali and humans. Perhaps some sort of plant that's strong enough to make them vomit and collapse, or an easily made tool that can make a sound loud enough to paralyze them. This will equalize power relationships between them, allowing a human to face off against a rampaging Amali. That will encourage the rest to work with humans, rather than against them. Their immense strength can be turned to the good of village life. [Answer] ## Pithing. The two species can't be on a level playing field. Traditionally, it is the role of a weaker population to enslave one with greater capabilities - for example, women were subjugated due to their ability to bear children, and American slaves were imported all the way from Africa at great expense because they could survive overwork, brutal conditions, and malaria all at the same time where other captive populations quickly perished. The werewolves could not have been bested in battle, but once lured into breeding, their offspring could be weaponized against them until they were defeated. In more recent times, to maintain the werewolves in a happy state, they are "pithed" early in development - their superior immune system and regenerative capability allowing them to survive a quite crude neurosurgery with a hot wire. With their limbic systems taken offline, and being selectively bred for a combination of the more convenient aspects of [Williams syndrome](https://en.wikipedia.org/wiki/Williams_syndrome) and [Angelman syndrome](https://en.wikipedia.org/wiki/Angelman_syndrome), they have proved to be cheerful and helpful servants. When necessary for war, they can still be reactivated by a crude adrenal extract of cattle, and workers in the field of animal electricity have been making fascinating progress duplicating this with implanted wires sparked by rubbing wool and amber. [Answer] Less Hostility towards People who are Different. There are many examples of human history where one group of humans does not coexist peacefully with another of humans. You propose humans living peacefully with some human wolf hybrids. To keep the peace you can change your people to remove their innate hostility towards people who are different from them. I suggest making them susceptible to pheremones from the werewolves so they activate the "It's a dog" part of their brain and not the "It's a monster" part. We don't like monsters. Oh no, monsters are big and scary and want to eat us. But we like dogs. Dogs are nice. Willk points out how the werewolves being ten times stronger and faster than the average person is not an immediate disqualifier. In the real world we already have people with guns who are ten times more dangerous than people without guns. Moreover some people carry concealed guns and so you cannot tell which are the dangerous people, compared to the werewolf where the fluffy ears and tails are a dead giveaway. The fact that these werewolves are emotionally volatile must be managed somehow of course. But once you remove the innate hatred between the two groups, this should be easier to do on a societal level, rather than a biological level. ]
[Question] [ This creature is an animal (specifically it is an organic lifeforms with nerves and musculature). It is covered in a single fused exoskeleton with no parts that can be extended out of the bounds of the body. It is roughly human sized What is the most efficient way to get around on land? [Answer] It must take a spheroidal shape, and the animal inside shall be arranged in such a way that it can freely move its center of mass. The animal will move by shifting its center of mass with respect to the point of contact with the ground. The direction where the CoM points is the direction where the acceleration will go. [Answer] Those creatures already exist. You should be able to find them on a rocky coast. On a place where the waves hit frequently or on a place that gets wet when the tides rise. I present you the Patella Vulgata, or limpet. [![Limpet underside](https://i.stack.imgur.com/yfHni.jpg)](https://i.stack.imgur.com/yfHni.jpg) Although you are not used to see that side. You will recognise them better in this other image: [![Limpet shells](https://i.stack.imgur.com/3sqHU.jpg)](https://i.stack.imgur.com/3sqHU.jpg) In truth, any type of snail with one shell fits your description perfectly except the size. Maybe you could use a giant snail: [![GiantSnailNotMyPhoto](https://i.stack.imgur.com/DVkxX.jpg)](https://i.stack.imgur.com/DVkxX.jpg) First 2 photos come from wikipedia: <https://en.wikipedia.org/wiki/Limpet> Last photo comes from here: <https://www.boredpanda.com/giant-snail-archachatina-marginata-adrian-kozakiewicz/> [Answer] Sailing stone style. [![sailing stone](https://i.stack.imgur.com/CCaMd.jpg)](https://i.stack.imgur.com/CCaMd.jpg) <https://en.wikipedia.org/wiki/Sailing_stones> These boulders move along when no-one is there. People return and see that they have moved. There are no tracks except those of the boulder. It turns out (as of 2014) the boulders are propelled by [ice shove](https://en.wikipedia.org/wiki/Ice_shove). > > However, as of August 2014, timelapse video footage of rocks moving > has been published, showing the rocks moving at high wind speeds > within the flow of thin, melting sheets of ice. The scientists have > thus identified the cause of the moving stones to be ice shove. > > > The sailing stones must wait for ice shove to come before they move. Maybe your creatures have ways to facilitate this? [Answer] How did this thing get on land? First question, very important. I assume from the OP that its method of locomotion will not work on land, but it got out of land anyway, so.... Natural selection If these things are ending up on land despite not currently being equipped to move on land, then natural law dictates that they will adapt or die, same as any other lifeform. The thing is, natural selection and evolution will always work with what's already there, so the real question is: is whatever method of locomotion they used before something that could work on land? If they moved using electromagnetic fields to propel the water around them (like a similar question's answer proposed), then they could, quite possibly, develop magnetic levitation and move just fine on land. Otherwise, then things get a little nutty.... 1. Hitchhiking Just like barnacles, these things are rock-like and immobile. Barnacles attach to marine organisms, and so can these guys (given a sufficiently large host). Of course, given it lacks mouthparts for filter-feeding, chances are it'd feed like a lamprey off said host, so this would result in big bloodsucking barnacles (BBBs). 2. My precious... Insects have chitin in a variety of colors, so why not these guys? Given the OP did not mention an excretion method, it may be that they store waste products, like ammonia and such, inside themselves in such a way as to render them toxic, which could naturally lead to A) bright coloration to scare off predators and B) humans who collect these "shinies". 3. Carriage through Camouflage Oh, if only these things weren't so dang big....anyway, a large enough creature could: A) collect these things in a pouch and spit them as projectiles, B) swallow these things to aid in digestion (which, granted, would greatly complicate survival) or.... C) stick these things on its body for additional protection, or else carry them on their back as a sort of shield that they can hide underneath. *3. Do they need* to move? This is a scenario, which may or may not work. We've all seen a mermaid perched on a rock, yes? Seems typical for them to bask on rocks, after all, predators can't really reach them up there-unless, of course, the rock is the predator!** Naturally, one would assume the mermaids would avoid the man-eating rocks, but what if they don't? What if the mermaids realize the rocks only eat one mermaid every so often and members of the school start sacrificing themselves so another schoolmate can bask on it? Or what if the mermaids move the rocks themselves to another school's territory, so that they get eaten by the rocks instead, starting an exchange? Or what if curious mermaids regularly go inside the rocks intentionally, arousing the curiosity of their schoolmates and leading them to form a mythos that requires one to be eaten to enter the afterlife? Otherwise, I'm afraid you've created an almost impossible scenario we can't answer except with additional information about how these things moved before they went onto land, and you may just have to handwave or conceal their mode of transportation beneath their massive bulk. ]

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