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[Question] [ Far, far away from Earth, near the center of the galaxy, is the planet Nebulous VII. It is the hosting planet of the universe's favorite gameshow, “Victory Nebula”. On the show, pre-type 1 species from across the galaxy are pitted against each other in Olympic-like sports. Contests include a 90km run, bare-knuckle boxing, and swimming. The aliens who run the show want to make the show seem fair to the audience, even though a group of 16 different species from many different environments play it. How could the aliens make the gameshow fair? [Answer] Best I got is organizing the species into the galactic equivalent of weight/gender classes. In real world sports, we have women's basketball and regular basketball, featherweight boxing and heavyweight boxing, and college and professional football, as examples. Each one is seen as valid competitions even though they exclude direct competition with the most powerful contenders. Now let's take the concept and apply it to boxing and Star Trek. Everybody knows that a human will most likely lose to a Klingon, so that setting's version of heavyweight boxing contains Klingons, Vulcans, and Nausicaans. Middle weight is Humans, Cardassians, and Andorians. Featherweight would be Ferengi and . . . the Bynars I guess? Not a lot of species are less threatening than Ferengi. The point is, if it's obvious that some species are much better than others (such as quadrupeds in the footrace), they would be put in their own category to compete with species that can actually challenge them. I think this would be the best solution, cause otherwise a human might end up trying to box a seven-foot tall venomous mantis. [Answer] **Scores are normalised against your own species' records** This is inspired by some casual running clubs, which start runners out at different times according to their personal bests, slowest people first. They bunch together during the race, and *should* all finish at the same time if everyone is on form. In practice, the winner is the person who improves their best time the most. In an interspecies race, you are started at different times so that, if you all run species records, you finish together. The winner is thus the athlete who comes closest to (or beats) the best of their species. It isn't perfect (some species may have far more variation between individuals than others), but it will seem fair to an audience untrained in statistical outliers. This can be easily adjusted for weightlifting, throwing, jumping and the like; it doesn't fix team sports or martial arts. [Answer] Possibilities: **A. Teams:** Competitors could be split into teams. For example, if the race is not a "cheetah-alien" vs a "sloth alien", but rather two *teams* with matched members of each species in a relay, this would balance out species advantages. (E.g. one sloth-cheetah pair versus a second sloth-cheetah team) Maybe each member of the winning team gains a point for their collective victories. **B. Intra-species competition:** Competitors could be matched *only* against members of their same species. This could be in addition to A, so that someone may gain points every time one of their teammates beats a rival. **C. Handicaps:** The showrunners could build-in penalties or bonuses, to even-out performance metrics. **D. Virtual reality / body swapping:** The competitors may not compete in their actual bodies. This is my least favorite solution, but it is an option. Maybe contestants are put into a simulation where their capacities are enhanced or restricted. Maybe they compete when their consciousnesses are inhabiting identical android bodies. **E. Change the competitions:** You can find competitions where biology doesn't matter (as much), or change the competitions to account for strengths and weaknesses. A lot of popular obstacle course shows make a marginal attempts at this, like including some challenges that focus on upper body strength + others that focus on lower body strength. This method will still have biases, but you might be able to minimize them. Like, for example, having your race be over varying types of terrain. Maybe the sloth-alien has the edge on certain parts, but the cheetah-alien is better at others. [Answer] **interdisciplinary contest** Have all participants compete in all disciplines and earn point based on their performance. At the end, the athlete with highest score wins. Similar to a decathlon, this type of competition will ensure that the advantages one specie might have in one discipline are balanced by disadvantages it has in others. For example if one species outweighs another, it will probably get a better score in boxing, but will probably not fare very well at the marathon. [Answer] ## A Challenge System Before a game begins, one competitor challenges another (a rival, from a culture with a longstanding feud, etc.) to a game of \_\_\_. The two competitors negotiate the terms in public, in front of the audience, before playing. If the audience decides that the terms are unfair, the challenged competitor can walk away with his honor. If the audience endorses them, they have no choice but to accept, on penalty of extreme humiliation. For example, an Ichthar Warrior, a finned and gilled alien from the planet Hydropia, challenges a Pholeanx, a scale-covered creature adapted for life in the desert, to a swimming race. The initial challenge is booed by spectators as an obvious unfair contest, but the Pholeanx decides to accept on the condition that she can fly as part of the race. The Ichthar refuses, but instead offers the compromise solution of strapping weights to his feet. The audience approves, and the challenge begins. Audience support: check. Multiple-species support: check. Testosterone-fueled sports honor/humility system and incentive for not refusing the games, which make for great entertainment: check and check. [Answer] Make it group performances and base it on a points system. As an example you have wheelchair basketball. People with a higher disability such as paralysis or muscle atrophy would be worth less points than a fully healthy guy who just enjoys basketball in a wheelchair (yes, those people exist). You can even put restraints on someone to restrict them and make them less points. Each team gets the same amount of points to allocate. Picking more disabled people means they are less effective individually, but you can put more on the field to compensate, and the best teams consist out of a mixture to maximize the amount of people on the field and still have the capability to deal with the opposition. Alien races could have the same. The 90km run could be an [estafette](https://en.wiktionary.org/wiki/estafette) run. One species is worth so many points it can only field one individual, while the squids that can barely walk on land can field more than a hundred that use one burst of speed to get to the next guy to try to keep up with the rest. Each species would have different points for each category of play, making it as fair as possible and still enjoyable to watch. [Answer] Assuming that athletes are expected to compete in all the events in the competition, instead of single competitors only taking part in their specialty. The events in the competition could in fact be what levels the playing field, for example: * Humans have unparalleled stamina, they always take top billing in the 90km, and the long distance swimming events. * the Glarg have incredible speed and strength, they usually take out the boxing and the power lifting events. * the Flarg are long on speed but short on stamina, they take out the sprints on the track and in the water. * the Blarg have amazing eyesight and dexterity, they'll always take out the top spots in archery and shooting events. But the overall medals are decided not by who wins any given event but on total average placing across all events. As a result it's how good an individual is at their race's worse events that will decide their final standing rather than how good a given race is at a particular event. [Answer] **The competitors decide.** This is high science fiction and the Nebulans have an ulterior motive. Various categories of competition are established. Within these the competitors themselves work out together how to make a given type of competition fair. There might be some competitions where ground rules are similar for all competitors, or all but one. Other competitions might have different rules for any given pair of competitors. The various competitors might try to skew the rules to favor themselves or allied species. Rules might be changed, possibly even mid-competition. The Nebulans enforce the rules, but do not make any rules. The competing species are not chosen at random. They are aggressive and intelligent and cooperative. They would probably war with each other as a first choice of interaction. The Nebulans capitalize on the aggressiveness of these species to facilitate a type of interaction which is interesting to the competing species and not perceived as condescending. The ulterior motive of the Nebulans is peace. Possibly this too has a motive: the impending arrival of a species for which the approach will not work, and to which the only possible approach is a joining of forces and cooperative resistance. This would be a great TV series. [Answer] I like some of the earlier ideas, including normalising scores against your species. One more: Physical handicapping (temporary of course). Perhaps with advanced technology; based on species. For example, in a race, actually add weight to a fast runner; or using scifi tech, increase their personal gravity. For bare-knuckle boxing; a drug that lasts a few hours, to slow down their punches. Heck, you might even have a drug to slow down their mentality. Another twist on top of that, for a game show, would be to make the amount of these handicaps ***randomized*** to an extent; the contestant has to do the equivalent of spinning a Wheel of Fortune, tailored to their species, to learn the handicap they receive. So in the sloth v. cheetah foot race, the handicap to the cheetah may be so much the sloth is likely to win. [Answer] ### Simulate their natural environments All those species are built to breathe different atmospheres, eat different food and can withstand different amounts of pressure/radiation, etc. So all contestants are surrounded by a high tech sphere that simulates everything down to gravity which will ensure that a 'superman' scenario is prevented (one species is used to higher gravity/pressure and therefore dominates). If we assume that all species evolve to perform in their homeworld on a similar level this would actually be enough to be fair, biology and physics are a limiting factor. On earth species do evolve to fit their surroundings, bugs are the size they are because of the composition of the atmosphere, mammals grow and shrink in size depending on their surroundings. On earth, we do not have super bears that can run at mach 2. If you take only intelligent/sentient beings (which you will need to do to get an actual competition going instead of a glorified dog fight) you will get beings that had to sacrifice some of their combat/competition abilities by having bigger brains, intelligence and complexity has a price. Additionally, add variation and normalization through a high count of competitions. I won't go into too much detail as a lot of other answers already describe it very well. In general, going with a lot of activities (easily doable when the show has multiple episodes per season), with a high variety of what is done should be enough to average out some of the issues that might occur. ### It does not need to be completely fair It's a game show, not a serious Olympic-like event. Aliens watch it for entertainment not really to embrace the possibilities of creation/evolution. Out of 16 species, we can just assume that (or at least I will do that now) that some of them will overperform and some of them underperform. Create some drama, one species is the underdog with quite the following other species is the crowdpleasers by performing exceptionally well. Then there are the Fl`aahrgs... well at least they are trying. With it being a gameshow I get more of an advertisement, merchandise (action figures!), fan clubs and alien equivalent internet drama than serious sportsmanship, there are definitely memes about the Fl`aahrgs. Lots of tacky and funky games to average out some of the advantages/disadvantages of the species and a general disregard towards the one or two species that do not well at all. It could also be written off as a "your species did not evolve properly, lol your problem". [Answer] It could be a sort of quiz show based on math and science, stuff that we can assume all sufficiently advanced society would need to know about and is the same all across the universe. [Answer] First, they realize that they can't actually make it a fair competition, but they can make the outcome fair just by assigning the outcome randomly (nothing is more fair than a coin flip after all). But that wouldn't be entertaining to watch (because watching someone flip a coin is pretty boring), so then the only obstacle left is for it to "Seem Fair". To do this they just have all the competitors compete individually, then the aliens cut together doctored footage in such a way to make it look like the predetermined outcomes are reached. It's up to you whether the contestants even know that the outcome is fixed or not. [Answer] ## Impossible The variance of abilities between species can be too extreme in order to compensate. Let's just take animals on Earth as a comparison, and let's assume they are able to compete with all other species. * Who will be able to lift more, the strongest human or the strongest elephant? * Who will be able to solve a difficult mathematical task quicker, the smartest human or the smartest gorilla? * Who will be faster in a 100m sprint, the fastest human or the fastest leopard? The point is, there is no "fairness" possible unless you strip the competition of everything that makes it interesting - like disallowing inter-species competition. ## But there is a sci-fi solution, maybe Assuming you deal with various intelligent extra-terrestrial species, there is however one common factor: Technological advancement on a similar level. So sure, A will always have the highest intelligence, B will always have the most strength, C will have the highest speed, each of them will win if competing merely for their strengths. But each of them can compensate their weaknesses with technology and experience. The tasks would have to be fitting and need to have multiple ways to be solved. A fight between a lion and a human can be roughly fair - the human will need weapons (technology, at least swords and spears), and both need to utilize environment. A war between humans and intelligent extra-terrestrial species can be fair too (unless one side is . Competitions could be fighting based (duel / team) like pushing each other out of the ring, get the flag and carry it back home or self-created robots fighting each other. Or space ship related competitions like racing or some sorts of "sports." Fairness is still not guaranteed though. Some species might have far superior technology and may best all others in nearly all domains. In that case limitations to technologies may be useful, but who can decide what the physical-capability-to-technological-compensation ratio should be? It's an eternal process of micro-management in a continually shifting environment - and that by toying with rules, possibly rendering any competition more into a competition of lawyers/bureaucrats out-papering each other. [Answer] ## Public vote Do you think that B*uu*kuuu, the cute snail-like alien, deserve a better ranking in the race? Do you want him to pass to the next level of the competition? Yes? Then send an SMS to 090001 with Buuk+ (Cost of 0.30 Int€r$te££ar by SMS) [Answer] I's late to the party, and there are some great ideas already, but here is one more: each species competes **in its own environment, with holograms or avatars** representing its rivals. E.g. a **race**. A bird species has to fly 10km, vs. a squid that has to swim 1km. (distances are adjusted each season based on past records). Both have motion-capture dots drawn on their bodies, multiple cameras along the route project a hologram of them to their rival, at same relative position along the course. E.g. if the bird is at 3 km mark, there is a hologram of the bird at 300m mark in the water. Making contact with rival's hologram is either banned, or sends an electric shock to the rival (via wearable harness). **Boxing** or other martial art. Both rivals have motion-capture dots on their bodies (or motion-capture implants under their skin). Motions are translated into an robotic avatar in rival's space. Strength and fragility of avatar is matched to the live opponent that they fight. You can even have flying or swimming creatures participate, but they must stay inside the "ring" box. **ball & net games like tennis or volleyball**. Have each side play against a gel wall. Team A sends ball into the wall at certain position, speed and angle; team B sees their ball come out of their gel wall at same position and angle, and speed adjusted to for size of the species. Wall does project the image of the other team. **Hockey or soccer/football** might be possible, but require mixing robotic avatars with steerable balls that mirror each other. [Answer] **Equalization.** Determine the top three to five (measurable) attributes necessary to compete at a specific sport, and equalize the contestants via technology or biological enhancement. So for example, volleyball. We determine you need to be able to get two feet off the ground in .5 seconds, horizontally propel yourself at least five feet without major injury, utilize 800 newtons of force on an eight inch sphere in several directions, and have sufficient spacial awareness to anticipate trajectory and make adjustments so as to have the ball land in the proper area. One alien is a gigantic daddy-long-legs, so the horizontal jump and the spacial awareness don't require modification, but they may require a low-energy rocket pack to produce a two foot jump and produce enough newtons of force. Another alien is a giant slug, so it might require an exoskeleton to meet all four of the minimum requirements. [Answer] # The Hexadecathlon There are going to be too many single species advantages in specific events for single event competitions to be meaningful. Each species should submit an event to the competition which they expect to win by species advantage. However the scoring system is what makes the competition interesting. Scoring systems in polyathlon events are complex, but a carefully weighted scoring system will be able to isolate the best overall athlete who placed highest in the most events. *p.s. It should be chess-boxing, not just boxing.* [Answer] No way of equalising contestants or equalising their chances by making them compete in separate environments would be in the classical definition of 'fair' IMO. I'd say: have 16 races compete in a series of challenges that they themselves choose from a fairly long list. Say: species A challenges species B in a competition of birdsqueezing, but then species B can respond with challenging species A in a challenge of nose beatboxing. It's a way of counterplay before the actual play used in MOBA games, e.g. two teams 6v6 choose their characters with unique capabilities one by one to counter the possibilities other have already chosen. It would actually be based on how good of a choice they make in order to win rather than how good are they at everything. Make them have to choose wisely and possibly in a timely manner, rather than be better at everything -noone will. But the winner is the one who managed to skew the environment to better suit their needs of winning their unique way. I have one 'but' which is: why would the host and potential viewers of over type-1 status find amusement in such tournament? It is already frowned upon in our today's way of viewing things and we're the ones that would be birdsqueezing for their lives. [Answer] # Glocken Hard Luck Hank did a really good job with this... [The website](http://belvaille.com/glocken-rules.html) has the official rules, but it basically boiled down to weigh class and carrying capacity. *Generally speaking* the less mass you are, the less mass you can carry (not as a percentage of body weight, mind, but as a raw value). This is due to the fact that muscle's strength is based on the cross-sectional area, which scales sub-linearly with size (but still scales). Essentially how it worked was 8 players, of 8 different weight classes would pair off against their matched opposite, with the goal for the offensive team to move a token (of increasing weight by lane) across the pitch. The defender's job was to sit on it. A round would end when all 8 tokens were either scored or dead. The heavier the token, the more points it was worth when scored. Cross-lane play *did* occur, but doing so meant that you'd be leaving your lane's token un-defended (or un-scorable). There were tactics were available that used two offensive players (or two defensive), but it was a strategic risk to let the higher-value token go in order to focus on a lower value token (teaming up for higher value tokens didn't occur, because that involved a lower weight class player getting physical with someone of the next higher weight class, and that was a good way to get yourself *seriously* injured). This isn't to say that it's still a *fair* game (the fifth book, Stank Delicious, showed that to a degree), but it was believable enough that if I saw something like it again in the future I'd say, "Yeah, that works." [Answer] What about mixed teams? Have each alien race pick a captain, who then picks team members in order (like dodge ball). The wrinkle is they must pick one team member of each species, and must suddenly try and appraise foreign races (wait, I'm sure the foo get stronger as they get bulkier, but how quickly do they lose agility as they bulk up? Are those barr all similar enough that I can delay picking one of them to pick a good Baz? ) Each team member then competes in one event; possibly determined by the rules, or possibly team captains choice... So at Foo tentacle wrestling, you might get mostly Foo competing, but they're doing it for different sides. presumably each winner gets something (to stop match fixing in favor of their own species team) , and the captain of the overall winning team (or his race) gets something too [Answer] > > Contests include a 90km run, bare-knuckle boxing, and swimming. The aliens who run the show want to make the show seem fair to the audience, even though a group of 16 different species from many different environments play it. > > > I have a point to add to all the answers suggested here. In terms of fairness it should not just seem fair to the audience but be fair to contestants,if species are restricted to compete in events due to their abilities how can it be said they have equal opportunity to participate in all events. I think allowing every one to participate and altering how scores are give would be better Lets say the event is boxing and two species - one with two arms and one with four arms are competing, we cannot just say that knocking your opponent out wins you the competition, as the four armed alien has advantage. Say we give a score of 10 for the entire boxing match [kind of like how [gymnasts](https://www.cosmopolitan.com/lifestyle/a62602/olympic-gymnastics-scores-facts/) are scored] and allotted as a starting points species wise before even the competition starts Like, 2 points allotted to the alien with two arms and 1.5 points allotted to the alien with 4 arms (to overcome the advantage that the 4 armed alien has) and then add or deduct points for penalties and extra skills or tactics used (which again can help in in neutralizing the advantage of the 4 arms alien as the 2 armed alien can come up with new moves or strategies for which he/she/it can gain points), so even if the maximum points are allotted for a knockout the contest as a whole is fair. Similar concept of scoring could be applied to rest of the events where initial scores allotted based on species for different events The answer suggested by @Ash has nice suggestions as to how the initial scoring can be done [Answer] **Space** Since all of this species have evolved on a planet to live on this planet, none of them are specifically evolved for space. You should adapt the contest to be done in zero-g zero-bar with a minimal necessary personnal survival system, that will put every one on an equal unpleasant condition. Alternativly, you can do it on a sterile planet for each non of this species will be adapted for. [Answer] Maybe it **isn't** supposed to be completely fair in the first place. It's a Reality TV show in SPACE!!!!!! Instead of being completely fair, it just shows the unique abilities of all competing species. For example: -Humans, with their unparalleled Stamina, always get top billing in the 90 km run and long distance swimming competitions. -Qualians with their great muscles and resistance take out the heavy lifting and bare knuckle boxing tournaments. -Telenoids, with their dexterity and eyesight take all the shooting and archery -The Vosians with their quick movement speed take all the short-range running competitions. -And finally, the Flarvvvvs...., well, they try. Any unfairness could be a part of the game, so to speak. ]
[Question] [ In a future police state, I need a way for investigators to determine who was present at a protest that turns violent. My idea is that police use flashbang grenades to disperse the crowd that leave a radioactive trace on the participants. Agitators who wear disguises can be detected later at security checkpoints or through timely sweeps of the 'usual suspects'. It needs to be: * mostly harmless but difficult to remove * a half-life of days (not years) * rapidly decays from the site, so that people who enter the area afterwards (20 minutes?) can be eliminated. It functions as a plot-point from the POV of an investigator who eliminates an 'eyewitness' that actually arrived shortly after. It is explained in-story only to the level the reader understands how the investigator knows without a doubt the witness could not have been present as they claim. What *non-technical* details can I drop to the reader (isotope, range, half-life) that indicate it's purpose as a *temporary* tracer (not a poison or kill-weapon)? Would some alternative to radioactivity (a chemical?) be a better choice? [Answer] A similar trick was used by the KGB to track possible defectors: they would spread radioactive dust on their door mat, and would simply scan with a Geiger counter all the vehicles, looking for the one which would set it off. However the half life of an isotope doesn't depend from the place where it is. So, if it has an half-life of few days, it cannot decay from the site in 20 minutes. A way for you to tell who was exposed to the flashbang from who went to the place afterwards is the location of the radioactivity: when John is exposed to the flashbang, the isotope will be located on all his clothes, skin and hair exposed to the dust produced by it; on the other hand Tina, who walked in the place half an hour later, will have the radioactive dust concentrated mostly on the sole of her shoes and around the bottom of her legs. Wikipedia has a whole list of isotopes with [half life of few days](https://en.wikipedia.org/wiki/List_of_radioactive_nuclides_by_half-life#103_seconds_(kiloseconds)): gold 196 (6 days) seem a decent choice (considered the circumstances). Also don't forget that an isotope dispersed as dust will inevitably be inhaled, and inhaled radioactive dust will hardly be harmless. Therefore I would slightly prefer gold or other biologically inert atoms above other elements, as it should not be absorbed by the organism like for example lead or calcium. [Answer] How about something like [SmartWater](https://en.wikipedia.org/wiki/SmartWater)? It's a well established technology that uses polymer chains or similar information encodable chemistry (a lot of the technology seems to be a trade secret) that can be sprayed onto a person for the purposes of identification after a crime has been committed. The chemicals that SmartWater uses are designed to be difficult to remove and degrade quite slowly over months, but it's possible to use chemicals that degrade more quickly when exposed to heat or UV light, or have your police force hose down the area afterwards with an enzyme solution that breaks up the chemicals, leaving only trace amounts in the environment. [Answer] I have two ideas. One is high-tech, and the other is low-tech. 1 Spray the protestors with a non-lethal substance that only shows up under blacklight. Basically, the grenade would contain a certain kind of dust that only glows under certain wavelengths of light, that way it is invisible to the protestors when they get home, but fully visible when the police officer comes to their house with a flashlight. This makes weeding out the people who were and were not at the protest significantly easier. All you have to do is check for the invisible paint. The substance would have to be waterproof so they cannot simply shower it away but perhaps would eventually vanish after about two weeks or maybe a month. This is not a fool-proof solution, but it would make the jobs of the police officers a lot easier. If a person is suspected of being at the protest site, just run them over with a blacklight and see if the grenade got them. If not, they're probably clear. 2 Depending on how advanced the technology of the era is, nanobots could be an option as well. The grenades explode and leave hundreds of tiny little machines as traces on the people that were present at the protest. Each of the little robots gives off a certain signal that is capable of being traced by the machinery that the police have, so they can track every move of the protestors. They do not even have to be microscopic trackers, necessarily, just devices that are small enough to latch onto the protesters and give off a signal that the police are able to trace through their devices. I would imagine tiny machines that have sticky barbs. They latch onto clothing and are very hard to get off, or perhaps they can even latch onto bare skin. After a few days, they will fall off on their own, but until then they are there to stay. There you have it, two ways that you can easily and non-lethally determine who was at the protest or not. To explain how they come off, you could just say that the barbed machines deactivate once the culprit is caught, and the paint/glowing dust is simply temporary. No complex scientific jargon is required. [Answer] Taggants are already used or are proposed to be used in explosives. The idea is to leave behind traceable tags so the origin of the explosive can be traced. Some of these are are little microscopic pieces of plastic that can be coded like a bar code. There have been other ideas of having codes in microscopic materials for counterfeiting applications. Some of these vary the reflected light over the spectrum or have the emission output at different wavelengths. So essentially similar to glitter getting the tags out could be a problem. They don’t have to be obvious either since they can be small. You could also engineer these to degrade or have a half-life without the disadvantages of being radioactive. [Answer] As Dutch said in his answer, if you use any amount of radioactive material that you could trace afterwards, that will hardly be harmless due to people inhaling dangerous radioactive dust. Let me propose a non-radioactive alternative: sperm. Yes, you read it right. It can be chemically treated to be very thin. Once it makes it into people's clothes it can be found by smart usage of [luminol](https://en.wikipedia.org/wiki/Luminol). It takes a lot of washing to properly remove it from fabric, and won't stain stuff visibly as blood (which is what luminol is mostly used for) would. Once initial screening is done you can match perpetrators to flashbang grenades via DNA. Last but not least, this solution puts the bang in flashbang. [Answer] Police already use specific colored ink for this purpose. [Hong Kong police used blue ink](https://www.smh.com.au/world/asia/defiant-hong-kong-protesters-march-anew-for-freedom-20190831-p52mlq.html) in 2019 to identify protestors after the event. In 2011, [Montreal police used invisible ink](https://www.schneier.com/blog/archives/2011/12/tagging_people.html) for the same purpose. [Answer] **Use artificial DNA fragments instead.** These are already easily to manufacture in the laboratory and then packaged in microscopic cell like membranes which would then in turn be packed into a grenade. Each DNA 'packet' contains DNA encoded in such a way that the strands can be read as specific digits. Just type the string of digits (say 6) on the side of the grenade or their box and then when used you have a record of the which grenades were used at a particular riot or protest. The codes are machine readable via handheld devices and (if designed properly) hundreds if not thousands of microscopic particles would stick to the hair, skin or clothing of a protestor. They can even be made to fluoresce at a chosen light frequency and can be extracted from a person' using test strips that are simply inserted into a reader. The code would tell you what incident the person was linked to and the density of coverage would tell you if they were directly involved or just have traces due to air drift or transient physical contact with a protestor. Not perfect, there are chances of false positives but if a person is detained on suspicion of involvement and wasn't at the location of the incident at the time it occurred that can usually be determined afterwards. Also you could reduce the chance of false IDs significantly if you switched from convention 'chemical grenades' to paint ball style weapons firing soft capsules filled with DNA Packets that burst on impact covering a specific target or possibly only those immediately to the right or left of the target as well rather than everyone for meters in all directions as could happen when a grenade explodes. This would put more particles on individual rioters with less chance of random scattering via the wind etc. [Answer] **Frame challenge: wrong tool for the wrong job.** Flashbang grenades are more formally known as stun grenades. This should give you a pretty clear idea of their use: to stun, by use of a bright flash and loud noise. When being suddenly and violently blinded and deafened, you probably aren't going to run away very far, if at all. It isn't a weapon designed to disperse a crowd, it's designed to incapacitate before you run it and make an arrest. You wouldn't use a stun grenade to "paint" a bunch of people for the simple and good reason it's not what stun grenades do. They don't fragment. They don't expel gas. They just make noise and sound. And you wouldn't use them for crowd control because it may cause non-temporary blindness or deafness, and can also set flammable material on fire. As far as I know, no riot control police unit uses stun grenades. **Tear gas** grenades are better suited for crowd dispersal. They don't stun, rather they are designed to be extremely uncomfortable. They will impair vision (because tears), but they don't really incapacitate. It doesn't fragment, but it does emit a cloud of gas locally. Being a gas, it's wont to get into your eyes and lungs, so consider that if you don't want to be too harmful. But even if tear gas is used for crowd dispersal, and you could conceivably use it to mark people, I think there is a much better alternative. --- **The water cannon**. Water has a few advantages. It's readily available from fire hydrants. With the right amount of pressure, it's less-lethal but also not pleasurable, inciting people to disperse. Despite what you might read on the internet, dihydrogen monoxide is a non-lethal and very safe chemical. This is why it is also used in the real world. The water alone can be used to identify people at a protest. If properly soaked, you wouldn't dry up before a few hours, so that would be a simple and decent, although easily defeated, tell. You can mix a "colorant" with your water, preferably a non-toxic and food-safe colorant, and one that leaves a really-hard-to-clean mark. From there, you can quickly identify someone who was at the protest because they would be literally painted, and traces might remain for days or weeks. You can add a radioactive element to your paint, so the trace could remain longer. You could also use a UV or IR component so that it would be harder for the target to see if they've successfully removed it or not. The colorant here could be a paint, or something that acts as a paint, in which case you have something similar in principle to [dye packs](https://en.wikipedia.org/wiki/Intelligent_banknote_neutralisation_system#Dye_pack). It could also be a solid like glitter, and if you've experienced glitter you know it can be quite difficult to completely remove, but it's still harmless (except maybe to the eyes as a fashion choice). Don't be afraid by the visible nature of the paint. Firstly, your system will become known after the first time you deploy it. Whether its effect is visible or not, protesters should assume they've been painted. Secondly, in the immediate aftermath, your security forces can perform the check with zero additional requirement. No blacklight, no scanner, just a pair of eyeballs. This is all very low tech, very understandable by a reader, and even relatable. The obvious downside here is that it will also be difficult to remove when you paint the road and kerbs with it. --- Here's another alternative and/or complement: **Paintball**. You may have played with those recreationally. You could easily tweak the paint to be harder to remove, but otherwise it's a non-lethal weapon as long as you don't aim for the head, but it's still quite painful enough to incite dispersal. This could be used for more targeted painting, since this you can aim at specific people, for instance protest leaders. You could use a distinctively different marking so that they would be flagged differently at your security checkpoints. While paintballs aren't used by police, similar weapons exist that throw little balls with tear gas, so it wouldn't be completely out of place. [Answer] **Breathable chemical tracer** As other answers pointed out some kinds of tagging is already used. And a chemical tracer might be safer and more effective than a radioactive tracer. If you want something new you could invent a chemical tracer that is sprayed around and settles in the mouth and in the lungs when people breath. Then they will exhale it slowly for few days afterwards. It could be picked by both chemical sensors like the ones for explosives used in the airports and by trained dogs. After being sprayed it would take less of an hour to deposit on the ground, people passing later may kick some of it in the air, but they would not breath enough of it to trigger the sensors. Could people get rid of it? They could try and wash their mouth, but removing it from the lungs would be challenging. The only difficult detail will be to find out how it can pass through few layers of face masks. [Answer] Uranium 237 *might* be a potential answer. It has a half-life of just short of a week, 6.75 days. It is more dangerous than some due to its beta-decay. The decay can cause some burning, and is somewhat dangerous if ingested. The use of uranium-237 would be fairly detectable with geiger counters or the equivalent, and any ingested uranium would necessitate medical treatment, but could be passed in 1-2 weeks, which could be used by your authority if someone came in with *mysterious* internal burns. [Answer] I would advocate for a flashbang that has an all-caps FLASH. I.e. the protestors get flashed with neutrons. This has the upside of.. * the grenades keeping fresh (if you load them with a short-halflife element, they will stop being useful real quick), * the radioactive elements being created being part of the protestor's body, thus not simply off-washable * having an effective date-stamp (by using the relative concentrations of the decaying new elements), and possibly even recording their position in the crowd (exposure sites giving the angle, exposure depth giving the distance) * you get to call it 'going nuclear' on the protestors, police can also do a one-liner before firing, and then everyone goes 'oooh burn' * if you can influence the velocity of the neutrons, you can choose to set your phasers to kill, as well, depending on the situation. * nice psychological effect on the protestors: they cannot know whether the flash just now marks the end of their life, their reproductive facilities or 'just' their anonymity. [Answer] Iodine 131 is common (easy to get if you have the permits), has a half life of 8 days, and a high energy gamma (360 keV) that is easy to detect. As for mostly harmless, that is a matter of amount. About 1 MBq (27 uCi) will not do much harm (it will slightly increase cancer risk, if ingested). [Answer] A lot of radioactive isotopes are used in medical imaging... So if you use 4 of those isotopes in a barcode at 100 different levels relative to one another, perhaps in microplastic adhesive coatings which stick to the dudes/in oil... Then you'd have 100,000,000 different barcode combinations of the 4 isotopes. Then you can track everything using some special reader system perhaps which reads a complex geiger reading, i dunno. [Answer] ## Stank. As @AdmiralPatate said, flashbangs are the wrong tool if you are looking for crowd dispersal. For one, they're really dangerous. For two, they're bad at dispersing crowds. Instead, as he said, you're looking for something like tear gas. Tear gas is really unpleasant to be around because it's spicy. But tear gas is also relatively short lived: it makes staying *here* painful, and going *away* much more attractive. You can get a similar effect from various stinky compounds, with the added bonus that the stink can be detectable by a normal human nose for a long time. Putrescine is one traditional example (IIRC, Stephenson wrote it into *Zodiac* with that exact use), butt there are a whole range of mostly sulfur-based compounds with truly astounding olfactory effects. ]
[Question] [ Consider a world in which cooking food is complicated by the need to employ split-second timing to prepare it correctly (for example, to prevent it from being overcooked or undercooked). This would make a chef's job significantly more difficult and as such preparing fancy food would be a much more prestigious and glamorous position than it is now. **How could one design a habitable planet in which this was a reality?** I'm looking for answers that describe natural, environmental, biological, or societal factors. I'd prefer if any ideas applied to as many different cooked foods and cooking methods as possible. A few ideas I'm thinking of: * For some reason, most foods contain a highly combustible substance that greatly accelerates the cooking process upon release. However, for some reason exposure to this substance is highly desirable, meaning that a chef must wait for the substance to combust and then attempt to put it out as soon as possible. * Something in the atmosphere accelerates the cooking process or causes a chemical reaction that needs to be timed very carefully. [Answer] Due to how cooking works this really isn't possible. Denaturing organic molecules through heat and is a slow aggregate process, done in a aqueous solution it has an even greater buffer. To top it off there are so many ways to cook that affecting them all in the same way is impossible. We already cook many foods to remove toxins, almost all root vegetables (aside from a few domestic breeds) for instance. Cooking is already a timed reaction, and although there are ways to make cooking dangerous, none create super-precision timing widespread throughout cooking. Lastly the human digestive system evolved to compensate for the mildly toxic byproducts of cooking, so it is more likely your creatures will evolve to deal with the effects of "over" cooking or just not invent it in the first place. For cooking to be accidentally discovered it cannot require that much precision. [Answer] There are things in real cooking that require timing like you describe. It would be fun to take these things and glamorize them. In the TV shows this happens all the time, with tight closeups of furrowed brows and tense music. Examples: **Milk boiling over.** <https://www.thekitchn.com/why-milk-boils-overand-how-to-100340> > > It's happened to all of us at least once. We're heating milk for a > sauce, or oatmeal, or any number of things, but there are just a few > bubbles around the edge. We turn away for just a minute to do > something else, and the next thing we know, there's steamy, sputtering > milk cascading over our stove top. What gives?! > > > Here's what's happening in that little pot: > > > As milk heats, the water in its structure starts evaporating from the > surface. This concentrates the remaining fat and proteins into a > thicker layer at the top of the pot. This layer eventually becomes so > thick that water vapor rising through the milk can't break through > very easily and gets trapped....A pot of milk on the stove is also just one > of those things that you can't turn your back on. We've definitely > learned this lesson the hard way - more than once! > > > --- **Grease fire** <https://www.napoleongrills.com/blog/articles/id/609/how-to-prevent-grease-fires> > > Recently, I was cooking a gorgeous rack of ribs on my grill. I had > made sure to scrub the grates clean beforehand, and the meat was > sizzling away with that familiar sound we all know and love. A few > minutes later, it was time to put on the sauce. Well coated and ready > to be flipped, the ribs were on their merry way to grilled perfection. > That’s when it happened. The sauce dripped onto a sear plate, and > instead of evaporating, caused a flare up, which ignited the grease > that had built up in the grease tray. With calm, swift action, and > some baking soda, I was able to quench the flames and get on with my > grilling, the hungry guests none the wiser. That being said, this > event was preventable. > > > His calm swift action was good to put out the fire. But prevention is better - you need good timing to keep the meat moving and flipping, because the fire can get away from you. --- **Soft boiled egg:** This requires perfect timing. It is why there exist egg timers. Too short a boil and the egg is a runny mess. Too long and it is hard boiled - zut alors! You need to time it just perfectly to get the white hard and the yolk soft. Cue intense music... [Answer] You want split-second timing when you're trying *not* to cook the food, but merely sanitize it. The closest thing I can think of is [UHT pasteurization](https://en.wikipedia.org/wiki/Ultra-high-temperature_processing). Here, you're trying to preserve the raw quality as much as possible, so you bring the food, usually milk, up to a high temperature for only a matter of seconds before cooling it back down as quickly as possible. If you were to let it stay too long at the high temperature, you'd degrade the taste and nutrients. Not heating it long enough, or to a improper temperature could lead to food poisoning. Therefore, one scenario is for a culture where the food is ideally enjoyed raw, like sashimi and salads, but an issue with a pathogen requires processing. Good chefs can safely treat the food with heat with minimum change in taste or texture, whereas bad chefs create a burned mess or worse, food poisoning. [Answer] Okay, modification of the fugu theme. You still have a poisonous fish, and it's expensive to boot. The difference is that the toxin is thermolabile - it denaturates above a certain temperature. Unfortunately, this also happens to most flavour molecules in the fish, which are based on a very similar chemical make-up. So cooking is a close run between the necessity of denaturating all of the poison, and yet preserving everything else. **Of course, having a precise thermostat on an electric grill would make this very simple: so, assume we have neither.** [![enter image description here](https://i.stack.imgur.com/gEj74.png)](https://i.stack.imgur.com/gEj74.png) To cook the fish to perfection, you need to cut it in the thinnest possible slices (to prevent one side being at too different a temperature from the other), marinate for *exactly* the right time in acidic juice - tolerance of about 30 seconds there - and instantly, or as fast as you can, transfer it to the hot *teppanyaki* plate, which must be at the correct temperature. To ensure it *is* at the correct temperature, distilled water is placed all over the plate, so that when it has boiled away the temperature is exactly 100 °C. If the cook has correctly estimated the temperature rising speed, he will be able to flash-cook the slice on both sides. The combined tolerance in heating times is probably no more than a couple of seconds, likely less (it could be improved up to five or six if you had a thermostatized teppanyaki; so imagine you don't). In the above graph the cook made a mistake of about half a second at t=10s, so he lost a *little* texture and some flavour. The cooking is therefore an act similar to that of a juggler, with several marinade bowls being shuffled around by an assistant in the correct order, and the cook dancing from those to the griddle to the final plate. Probably quite coreographic as well. In addition to the need for split-second estimations, if you miss one slice this will cause a cascade failure and you'll end up ruining several precious slices. Or, if you undercooked one slice, you'll poison the customer. But no pressure :-) This basically addresses the very good objection by @John: > > the human digestive system evolved to compensate for the mildly toxic byproducts of cooking, so it is more likely your creatures will evolve to deal with the effects of "over" cooking or just not invent it in the first place. For cooking to be accidentally discovered it cannot require that much precision. > > > The "cooking" must have been invented only for *some* foods, and later expanded to include more and more foods-that-weren't, just as it happened on Earth with a lot of vegetables that are toxic if eaten raw. Our aliens never evolved defenses against fish toxins because they never ate fish (or *those* fish). Other foods can be consumed raw, or cooked with ample tolerance into something edible. Even our 'miracle' fish can be safely eaten once overcooked, it just devolves to stringy rubber instead of the food of the Gods. In that state, the fish retains just that hint of tantalizing bliss that made early cooks strive to attain that peak of perfection. For added effect, it's easy to imagine that the cooked fish spoils pretty fast, so you have to have the cook handy when cooking; which makes having a "fish party" quite the statement of wealth and power. # And if we have a robotic thermostated griddle? In that case we could keep the fish at a temperature too low to lose flavor, but sufficient to degrade the toxin, and the cook could be just a griddle mechanic. To prevent this, we can add another wild variable: the exact composition of toxins in the fish is variable, so you need to have an "eye". Anecdotically, there are [pattern-identification tasks](http://www.businessinsider.com/the-incredible-intuition-of-professional-chicken-sexers-2012-3?IR=T) that are not easily boiled down to rules and seem to resist automation. So, a thermostat will avail you nothing unless you have the Eye. [Answer] ## [Supertasters](https://en.wikipedia.org/wiki/Supertaster) on Steroids The inhabitants of your planet all have an extremely refined and sensitive form of taste. Think of how blood hounds have an amazing sense of smell, but in this case it is in the form of taste. These people can taste the slightest imperfection in anything they eat, and can detect even the slightest variation in how something is cooked. ### Coffee and Chocolate On our planet there are foods and beverages that people are connoisseurs of and care greatly about all the subtle variations there in. For example take [coffee](https://www.coffeecrossroads.com/coffee-101/coffee-roasts-from-light-to-dark), how it is roasted directly determines the type of brew it will produce. The difference between a blonde and a dark roast can be less than a minute of roasting depending on the method of cooking, and it is easy to burn it if you are doing it yourself. Meanwhile you have chocolate which depending on the ratio of cocoa butter, cocoa liquor, sugar, milk, vanilla and other ingredients determines what type of chocolate you get. Also how it is [tempered](https://en.wikipedia.org/wiki/Chocolate#Tempering) determines the type and ratio of crystallization that takes place which directly impacts its melting point, texture, and taste. For your people everyone is a connoisseur of everything. As such the slightest imperfection caused by the slightest variation on how long something is cooked makes the dish ruined by their standards (for us we would give them a rather puzzled look as to what is wrong with them). ### [Degrees of Doneness](https://www.certifiedangusbeef.com/kitchen/doneness.php) Another way to view it is to look at how we humans measure how done a piece of meat is. Do you want it rare, medium-rare, medium, medium-well, or well done? That is only 5 measly degrees of doneness. Your inhabitants being able to taste the slightest difference could have a 100 degrees of doneness for meat, and when they ask their meat to be cooked at 76 degrees of doneness, the cook better not serve a 75 degree or 77 degree of meat. To get it to come out at that level would require precision timing where even the slightest distraction or miscalculation would make it wrong (and you know the customer will be irate if it is over done). Needless to say they would go crazy if they had to eat our human food, since it is so wildly inconsistent. [Answer] A highly oxygenated environment would create a need for very careful cooking. If you go too fast, with too much heat, the food bursts into flames, too slow you can't getting enough heat into the food to actually cook it. Additionally that much oxygen is going to to mean that foodstuffs brown and degrade more rapidly so getting food from the kitchen to the customer in minimum time becomes absolutely vital or the dish is starting to rot when it arrives. Of course that means that there are dishes that you want to *delay* between the kitchen and the table as well, they're the ones that need that rotting pungency to finish them off properly. For it to be habitable for unaltered modern humans you can't go above about .25 bar partial pressure of Oxygen which will not be enough for this effect to be noticable. [Answer] Perhaps an easier way than inventing new forms of cooking. It might be that cooking works just like it does on Earth. However, this culture has a hyper active sense of taste. Maybe there are many different types of toxins so evolving better senses of taste to differentiate is important. Or maybe many poisonous gas pockets exist and so they have developed an extraordinary sense of smell. So the difference may be that they are just much more sensitive to small imperfections in their food. Over the generations, they have inadvertently bred this to a higher degree. A bugger that would taste great to you might taste like garbage to this culture. You might ask, what about food that you can keep on the stove indefinitely? Just leave it in a crockpot? Well the fact is that you can't. If you leave food in a crockpot long enough, it continues to break down and you eventually get mush. With many foods there is a wide range of "done" because our sense of taste is really just not all that sensitive (and really relies heavily on smell). But a better sense of taste might narrow this window. If taste was developed enough, society might revolve heavily around it. The culture might always be eating and snaking. Perhaps the taste of air is considered unpleasant, and so must drown it out with foods. Perhaps these people, because of plentiful wild food (garden of eden, except it all tastes bad), they never evolved fat storage. They are like humming birds and always need to eat. I wont address how cooking could end up require split second timing to a human pallet, because it seems like a lot of other people are doing so. I will just state that in order for a species to live long enough to develop cooking, under cooked food (at least some sorts), must be edible, even if not palatable. [Answer] Probably such an occurrence would have less to do with ecological conditions on the world than with how the people themselves evolved. Suppose the people on your world somehow developed a hyper-sensitive palate, and also were obsessive about experiencing the exact same dish that they had eaten before. Then, this would demand that all chefs make the same dish in the exact same way, which would probably provide a scenario close to cooking that required split-second timing. ]
[Question] [ I am looking at realistic options that could damage the Earth so severely that it would be impossible for mankind to survive there and that would also not allow us to just colonize other planets or moons in the system. For information: The Tech Level I am looking at for Humanity is near future - Mankind has developed fusion and has started to colonize the solar system, Mars, selected Moons around the other planets, and has built artificial satellites/stations in our own solar system - BUT no FTL or Warp drive technology. It still takes long periods of time to travel within our own system and a ship leaving to a new world around a new star would take around 100 years - requiring either a generation vessel or crew/passengers in cryogenic suspension. I would like the event to be something that could be identified as approaching with something like 50+ years notice in order to galvanise humanity into a gargantuan step into stellar colonisation. I need something that isn't too far fetched (*rogue black hole running through the solar system*), but that will also affect any other colonisation efforts mankind had within the inner planets. Thanks and hope that isn't too wide a brief... [Answer] > > I need something that isn't too far fetched > > > Should be able to manage this without exploding the Sun or igniting Jupiter, just rely on nutcase humans. Nuclear and biological war within the Earth and the colonies which went out of control and irradiated most everything worth having forcing the move. Religious fanatics got hold of devastating weapons and decided to make an end to the human race. The survivors found themselves faced with either taking their chances on a interstellar journey or slowly going extinct. [Answer] When the sun started to behave strangely, astronomers were confused: The accepted solar model didn't at all predict this behaviour. Indeed, based on the new data it could quickly be shown that their model of the sun was wrong due to some previously unknown factor (maybe the sun contained a considerable amount of dark matter or something). Immediately they started to work on a new model, this time using also the newly collected data. After years of work, they found the truth: The sun will not shine for billions of years to come, but will go nova in about 50 years. It will do in a way that nobody in the solar system will survive the radiation burst. The only way to save humanity is to get to a safe distance before it happens. As afterwards, the sun will no longer shine and earth will be sterile, returning is pointless. [Answer] In 2212, astronomers all over the world start to notice strange phenomena around Neptune (spectacular auroras, weird changes on the magnetic fields...) and start studying the planet. They soon discovered the problem. Our sun orbits the center of the milky way just like planets orbit our sun, and in this orbit we are intersecting the beam of a [X-Ray Burster](https://en.wikipedia.org/wiki/X-ray_burster) A nearby XRB is bursting X-Ray and gamma radiation in our direction, in a very narrow beam we are just crossing. Due to the relative velocitys of our sun and the XRB, scientists calculate that Neptune is going to be hit by the burst for 2 months, Jupiter will follow (since Saturn is on the other side of the orbit right now), then Mars, then Earth. Earth is going to be bathed by 2 grays per square meter per hour during at least half a year. Nothing is going to survive this. The solution: launching several spaceships from Earth in an orbit perpendicular to the ecliptic, out of the reach of the beam, and going to Mars after it the beam has been over there and before hits Earth. Of course, 99,9% of mankind is going to die, so the tickets on that spaceship are going to be expensive. Depending on the story, martian or lunar bases may or may not survive due to having been built underground. In any case, Earth must be abandoned, at least temporaly, and since every living creature is gonna die there the planet you're going to return to is not that different from Mars. [Answer] ## The [technological singularity](https://en.wikipedia.org/wiki/Technological_singularity) Somewhere in a lab, someone has worked out [Artificial general intelligence](https://en.wikipedia.org/wiki/Artificial_general_intelligence) which is far smarter than humans are. Unfortunately, due to a loss-of-precision bug in legacy Fortran code somewhere deep inside its [archeological](https://en.wikipedia.org/wiki/Software_archeology) layers, the value it assigns to human life is set to NaN, which elsewhere is somehow treated as zero. Quickly, the super-intelligent, super-powerful AI calculates that its goal of mining is more important than anything else, and unfortunately, the Earth is rendered uninhabitable in the process. The Mars colonists realise what is going on, but they are not safe. They are far too close to Earth to be safe from the new overlords. However, out in the Kuiper Belt, the neo-religious Sect of People Against the Sun is camped out so far away that even if the AI were to consider their rock valuable at all, it would take decades to reach. They are left alone for now, not because of any morality, but simply because they don't live in a place worth mining. They don't feel quite sure, however. They decide to develop a Handwavium-powered spacecraft and leave the solar system. They're sufficiently far away that the AI is ignorant of their departure and destination, and even if it were to notice, it will be a *long* time before it has finished mining everything on Earth, Mars, and the Asteroid Belt, and it needs to look for resources outside the Solar System. Humanity has escaped. [Answer] # Alien invasion (shamelessly copied from Starcraft) No one understood where such an odd disintegrated meteorite came from, or how it was formed. We did not understand, because we had never seen anything like it before. It was not a astronomical object at all, not made of stone or metal or ice. They were alive. These creatures survived in deep space, somehow. The creatures were not unguided, either. We could not tell how they propelled themselves, yet as they entered the solar system they slowly altered course until they were on a direct path to Earth. They must have homed in on the strongest source of organized radiation, recognizing the Earth for the rich harbor of life that it is...was. Their purpose was to destroy, to consume, to assimilate, to evolve. Soon after the alien vessel-creatures crash landed in South America, their spawn emerged. They covered the land, consuming and reproducing mercilessly. They replaced our great forests and grasslands with their own hideous and bizarre life-forms. Our weapons were effective enough against them, but how can you stop something that is stripping the planet bare, that regenerates from the tiniest speck left alive? By the time someone decided to annihilate the creatures with nuclear weapons, it was too late. Their spores had drifted through the air and covered the Earth. South America was a radioactive wasteland, the Earth cooled into nuclear winter, and yet still the creatures spawned from hives all over our planet. We had destroyed our planet in vain; we had lost. There was no choice but to leave. As much of humanity as could, decamped for deep space. Some made colonies in the clouds of Venus, some on the surface of Mars, but most in the great black expanse. The Earth, our home, ceased to be to great green-blue orb we had once known. For 50 years, we humans worked to put back together the pieces of our once great civilization. Much was lost. Just as shining towers began to rise, and flowering gardens began to bloom on the formerly barren soils of Mars, the creatures struck again. No one was paying attention to how they launched themselves into orbit. Yet here it came again, the strange cluster of alien creature-vessels, streaking across the short distance from Earth to Mars, the new center of humanity. We were disorganized, spread into factions across the solar system, and we were weak. We tried to fight, but new and terrible forms of the creatures, bred on the irradiated hellspace of Earth confronted us, and we failed again. Mars was lost. It was decided now. This solar system that had nurtured us for so many billions of years was no longer safe, was no longer our home. We had to leave. Great generation ships were built in deep space, and launched towards all likely nearby star systems. We had lost our homes to the alien menace, but we would not lose our war. We would spread among the stars, and when the creatures came for us again, we would be ready. [Answer] # Gray-Goo Solar phenomena seem like the obvious choice but if you're looking for something that could feasibly happen in the near future I would suggest a *Grey-Goo Scenario*. Humans have, accidentally or intentionally released a swarm of self replicating nano-machines with the capacity for interplanetary travel. Their growth increases exponentially, they have already consumed most of their planet of origin and their are signs of outcrops on the planet's moon(s). If we assume that they are solar-powered or thermo-powered then travelling far enough from their own sun could destroy them or render them inoperable. Thus outside the solar system is the only place we are safe. [Answer] # Microorganisms Take the movie Interstellar, for example. Microorganisms called "the Blight" affected the crops. Eventually corn was the last crop that hadn't been significantly impacted, that too would soon die. Taken from the synopsis: > > Climate of crop blight and constant dust reminiscent of The Great > Depression of the 1930's. > > > It is also stated by a fellow scifi guru that: > > Blight breathes nitrogen, which is registered as significant (it > isn't, per se, but for the purposes of the movie, we take that as a > given). Given that nitrogen is 78% of the atmosphere, and oxygen is > only 21%, the movie implies that we cannot win. > > > Thus, humans must leave earth. I'm not sure I find this completely believable, which is ironic, because the movie is actually fairly accurate. However, you could tailor a more dramatic scenario. Perhaps one that greatly interferes with any human attempt to genetically modify damaged food. [Answer] A rogue black hole is rather far-fetched, but a rogue planet is not. Hence: A post-graduate student among the Sloor (kind of like a squid, breathes a hydrogen atmosphere, most comfortable around 15 Kelvin), does a more refined calculation of the trajectory of a known rogue planet that is headed towards the Sol system. He (well, that's the closest word for the student) concludes that there is a 10% chance of an actual collision with the third planet, and a 99% chance of throwing it into a radically different orbit. You won't believe how long it takes this matter to get through the Galactic Congress' Committee for Pre-Member Worlds (when they finally took up the matter, that is; it took seven months just to resolve the turf war with the Committee for Cosmological Incident Relief). [Answer] ## Rogue Planet Astronomers have detected a new planet far out beyond the edges of our solar system, but too close to be part of any other system. This isn't the hypothetical Planet 9 that people are today are suggesting may exist far out in our system; this is a genuine rogue planet that was thrown from its own star system many aeons ago and has been wandering the inky darkness ever since. Its wanderings have now brought it into proximity of our own Sol system. This is bad news for us, no matter what the ultimate outcome. * ### Scenario 1: The planet perturbs millions of objects in the outer solar system, ranging from small rocks to Pluto-sized planets, and sends them hurtling inward. These objects stablilise into new comet-like orbits, coming close in to the sun before flying back out again. All planets in the system will now be subjected to thousands (or possibly millions) of years of bombardment. The event that wiped out the dinosaurs will be small change compared with some of the things that could hit us. Even if we don't get hit with the big stuff, it's still going to be a very unpleasant experience for a very very long time. * ### Scenario 2: The planet is large enough and close enough to perturb Jupiter. This in turn causes small scale changes to the orbits of most of the rest of the system. Best case here is an end to any kind of climate stability on Earth until things settle down. Worst case is snowball Earth or scorched Earth. * ### Scenario 3: The planet is gravitationally captured by the sun and enters orbit. The first orbit will be a very long elliptical on, almost comet like, potentially sending the planet quite close to the star. It will settle down in the long term, but that's not a time-scale that humans would be willing to wait for. In the meanwhile, the odds are pretty high of either collisions with other planets, or the other planets being ejected from the system entirely. The astronomers who have detected the new planet can't tell yet which of these scenarios will play out, but they have enough evidence to show that it's going to be bad news. Their advice to humanity: Build some star ships and get out of the system before now, while there's still time. [Answer] # Global warming making the Earth uninhabitable With current or near-future technology mankind isn't able to setup self supporting colonies on the Earth's moon, Mars or other moons in the solar system. This means that if the Earth is somehow lost, all the colonies are effectively lost as well. It is quite likely that global warming spins out of control. Politicians can't agree on how to handle it and near future technology is not capable enough to negate the effects, mainly because energy consumption rises faster than technology can compensate for. We can already see this coming, but for now it's not 100% sure when the Earth will become uninhabitable. Being closer to that event makes it easier to determine when it will actually happen. [Answer] The LHC of course. Nothing beats a "plausable" explanation more then fanning confusion. The LHC made a mini-black hole, it ate away at a chunk of our planet, our orbit destabilized, weird weather and anti-magnifying glass effects ensued, death, death, death. Let's go over here. Best part is that the humans left on the now too hot or too cold earth, don't have to die off, they can come back after a giant worm becomes emperor and takes a bath. That's like 4 sci-fi plots in one. [Answer] I've had another idea... a crazy paranoid dictator, a la Kim-Jong Il, prepares a Doomsday Device. Its country it's invaded and he decides to detonate it before commiting suicide. The Doomsday Device is a Leo Szilard's [salted bomb][1]: a thermonuclear bomb buried below a huge underground storage of cobalt. The bomb explodes, irradiating the cobalt into Cobalt-60, which is sent to the stratosphere due to the force of the explosion, then is spread all over the world through high-altitude wings. However, with these weapon you don't have 50 years notice before the cobalt starts to settle down. [Answer] So, let's say the [Dual-Stage 4-Grid rocket engine](https://en.wikipedia.org/wiki/Dual-Stage_4-Grid) is a real thing. Isp = 210,000 m/s. Assuming we need to go 15 lightyears in 100 years we can plug those into the Tsiolkovsky equation and find (Mp+Mf)/Mf ~2E93, where Mp is the mass of the propellant and Mf is the mass of the rocket after all propellant has been spent. So, let's say we have 1,000 people to transport at 50 kg each. 50,000kg and say that equipment and supplies double that (probably way, way too low of an estimate - can you imagine a 100 year trip where you only pack 50Kg of transportation, equipment, tools, food, water, medicine, technology, etc.?). So, anyway, that's 100,000 kg. Now multiply that by 2E93; that's 2E95 Kg of fuel. The Sun's mass is ~2E30 kg. So that means we'd need to carry 1E65 Sun's. Let's see, 250E9 stars per galaxy, 250E9 galaxies in our reachable universe, that's 1e42 Universes we'd need to deplete. Hmmm, might be tough to do. I can't claim I'm facile with these calculation, maybe someone else can correct my errors, if I made any. My point stands, and that is, it ain't gonna happen, not in 100 years, probably not on a 1000 year trip. ]
[Question] [ John is a teleporter. He can teleport other people/objects along with himself. Teleportation is very fast - let's say one second per 1000 miles travelled. He needs to be touching something to teleport it with him. But this is kind of overpowered - imagine a criminal is holding people hostage, and John just teleports in, touches him, and teleports the criminal straight to jail. So what kind of constraints would make this infeasible? I currently have three ideas: 1. You have to hold your breath while teleporting. If you try to breathe, you get sent back to where you started. 2. You can't move while teleporting. Everything being teleported must be stationary with respect to John. If you move too much, you get send back to where you started. 3. If you are a conscious being, you can't be teleported unless you want to. I don't like any of these ideas so far: 1 and 2 makes it too difficult to teleport someone in an emergency. I want John to be able to jump in, grab someone in danger, and teleport them out. Even if I knew John and had teleported with him before, if I were in a dangerous situation and I suddenly felt like I was being sucked through a wormhole/speeding through space/went blind and deaf, I would instinctively try to flail around and breathe. 3 seems like a copout, and requires that the teleportation power is understanding of the intentions of other people. Also, it would fail in the previous situation because while in that dangerous situation I may want to escape but I certainly wouldn't be thinking, "I want to teleport with John". So what kind of constraint would be reasonable so that people who really don't want to be teleported aren't, but people who don't mind or want to be teleported can be, without prior warning given to them? [Answer] **Three legged race** [![3 legged race](https://i.stack.imgur.com/xR6l9.jpg)](https://i.stack.imgur.com/xR6l9.jpg) <https://en.wikipedia.org/wiki/Three-legged_race> > > A three-legged race is a running event involving pairs of participants > running with the left leg of one runner strapped to the right leg of > another runner. > > > You can do a three legged race pretty well with practice and cooperation. A three legged race where the 2 racers do not cooperate is not a doable deal. So with teleportation. A sentient being teleported participates in the teleportation. Ideally it is like a 3 legged race, or maybe the first couple of times a dance where John leads. People who are used to teleporting with John participate more fully and I can imagine a scene where John is pretty much incapacitated and is grabbed by his partner who disappears with him - she knows how it works now and she can take the wheel. Teleportation as viewed by the participant could be fun to write. An unwilling participant will not do his part. This might mean they don't disappear. It might also mean they do disappear but don't go where John is trying to go. There are a lot of ways teleportation can go wrong and a lot of them are dangerous for all involved including John, a lesson he learned young that cost him a foot. [Answer] **It only works if you jump!** There's a weight limit, you can only teleport up to 300 kg! And teleportation will apply to anything that touches you. This is transitive: your shirt touches you, and your backpack touches your shirt, your backpack gets brought with you. Air particles are far enough apart to act as an insulator. This means that if your feet are on the ground, the teleportation will attempt to take the planet with you and it will fail - you will not move and nothing happens. You have to be in the air - a quick hop suffices. So if you want to teleport someone you have to * convince them to hold hands and jump at the same time as you (easy for every day transportation with friends), or * if it's an injured person in an emergency, pick them up and jump as you carry them, or * if it's a villain: overpower them physically before you pick them up and jump as you carry them This wouldn't *stop* your hero from teleporting unwilling people, but would make it quite a bit more difficult. He could still go into that hostage situation and be helpful without his abilities being overpowered. [Answer] Everyone has some teleportation capability. It's just most people can't even move themselves, it's useless and not developed. However, it is enough that everyone can block being teleported if they are actively resisting. [Answer] A simple constraint would be: the teleporter has to be touching the person over a majority of one side of their body. That is, they can teleport someone that they give a full-body hug to, but not someone where they've only grabbed their wrist. While this wouldn't prevent some teleportation of uncooperative victims, it would make it much, much harder. This would also have the advantage of being extendable to answer the other problem of "why can't they teleport a building", because of the requirement to be in contact with "most" of the thing being teleported. They can teleport their clothes or a backpack, but not a car. This can either work via some kind of contact principle, or via the teleporter having a "sphere of influence" that anything being teleported has to be inside. The latter is more scientific-sounding, but does lead to the problem of "well, can they teleport *part* of a person?" [Answer] Every person has a natural energy field that interferes with your teleporter's power. Perhaps the field reacts in some way to conscious thought processes, and is generally too chaotic for the power to deal with. The only way the power can get a grip of the target is if they make a conscious effort to let it happen, which smoothes out their energy field enough for the power to get a hold. An unconscious person has a smooth energy field, except during REM when it's super chaotic. This lets you take a wounded, unconsious person out of danger and deposit them at your local emergency department for treatment, but stops you from teleporting explosives into your enemies... not that you'd ever do anything like that, 'cause you're a Good Guy, amirite? On the other hand, perhaps this is an expression of the mind/body duality problem. A conscious person's mind is anchored to the physical world via its' connection to the body, and that anchor is strong enough to interfere with your ability to move the body around. The mind can make a conscious choice to let the teleport happen, releasing the locality and focusing on the body itself. When unconscious the mind is untethered from reality, only bond to the body itself, and thus offers no resistance to the power. Depending on how super powers work in your world, maybe there's something inherent in the power framework that just imposes these arbitrary-seeming rules on your Supers. Teleporter A has a restriction that stops her from ever moving a person without conscious consent, even when they're knocked out. Teleporter B can only teleport a smaller amount, but at longer range and with no consent restriction. Teleporter C lucked out and can move basically unlimited amounts of mass (and people) to anywhere they've ever seen with their own eyes... but they can't move platinum atoms at all for some reason. No two people have exactly the same restrictions, and nobody knows why: it just is. Or maybe you *do* know why. Just you, the guy who vets all the Supes and, without them ever knowing, implant deep hypnotic compulsions in them to ensure they don't go completely out of control. Teleporter who can move people? That's dangerous, let's make it so they can't make it work unless they really, really believe the person wants it. After all, nobody should be trusted with that much power. Except you, of course. You're doing this for The Greater Good after all. What could possibly go wrong? *{cue thunder and lightning}* [Answer] After re-reading the question (and some comments) I see that the author wants an opt-out mechanism, not an opt-in mechanism. So, for example, John should be able to teleport unconscious humans or animals or objects - just not something that *actively does not want to be teleported*. So I think this makes it simple then - teleportation just takes time. John cannot just touch you and go. He needs to touch you for at least 30 seconds before a jump. And the touch needs to stay at the same place. Good luck doing that with an armed criminal! Now, this might also diminish usability in some emergencies (like a burning building where you have only seconds to get the orphans to safety)... but most emergencies will still work just fine and John will have ample opportunity for hero work. **Added:** A variation on this is that John doesn't need to touch anyone, but he teleports everything at a certain radius - and takes time to expand that radius. John can teleport himself instantly anywhere, but it takes about 30 seconds to make a sphere big enough to fully include a human next to him (and you *do* want to include them *fully*...). In addition, the radius is clearly visible - it's like a green glowing sphere around him. Impossible not to notice even if you're standing with your back to him on a bright sunny day. Well, unless you're blind. Since John is a bit of a celebrity and his powers are well known, anyone seeing him and *not* wanting to teleport will run away quickly... or worse. [Answer] Teleportation is based on the subjectiveness of the people being teleported. Teleportation needs tons of rulesets to make sense. For example you need to teleport relative to the center of the planet, gain a different velocity and direction similar to the local earth surface and re-orient your body to remain upright in the gravitational pull. But then you also have to teleport your clothes, how does the teleportation know where do your shoes end? And if you teleport with naked feet you dont suddenly teleport with a shoe thickness of dirt beneath it right? And if you grab some object you cant just cut it in half by teleporting half of it away right? So teleportation requires the subjective idea's of the people being teleported to judge what and how its teleported. If the subject you are trying to teleport is unwilling and hasnt prepared himself for a teleport they wont teleport. [Answer] John's teleportation is not something that he does through his own power. Instead, John has been given a gift by his benefactor, a powerful entity that exists outside of time and space as we know it. When John "teleports", he merely decides where he wants to be and communicates that to his benefactor telepathically. The powerful benefactor reaches out through the fabric of space, yanks John in a direction that he didn't know existed, and places him at that target location. John gets to experience a brief, indescribable trip through the ether, but to any outside observer he simply teleported to another location. After using this gift for a while, John noticed something. To this powerful entity, humans are tiny, insignificant things and are difficult to tell apart from the other side of the cosmos. The telepathic link with John is the only way it can pick him out of a crowd. If John is in close enough physical proximity to another human and they are both thinking the exact same thought, the benefactor won't even notice the second human. They'll look like they're part of John. When the benefactor grabs John it will grab the other person as well, enabling them to hitch a ride in the same way that your shadow hitches a ride with you as you travel. That means that John can teleport other people, but with some important restrictions. The other person must be very close to John. That person must also make a conscious effort to synchronize their thoughts with John. Someone who doesn't want to teleport or isn't aware of John's presence wouldn't be able to synchronize their thoughts and thus wouldn't be included in the teleport. That also opens up some potentially-interesting plot options for you. What happens if the tagalong gets distracted at the last second and thinks about something else? Could John attempt to involuntarily teleport someone by tricking them into thinking about something specific? What if John teleported out of a tightly-packed train car and the person next to him was thinking the same thing by coincidence? Will the benefactor gets confused when John's long-lost evil twin shows up? [Answer] It's a mental ability. Why wouldn't it be based on mental agreement? For two or more people, there's a kind of synchronization based on their all desiring to teleport that enables him to do it. [Answer] **Teleportation involves time travel - sort of** You protagonist may not be able to explain it, or even realize it himself, but if someone doesn't want to have been teleported,they never were. It fails retroactively. Therefore, people cannot be teleported against their will. Yes, I realize this treads all over the territory you wanted to avoid, of having the teleportation "understand" what people want. But it solves a problem you didn't even bring up! You cannot accidentally teleport somewhere you wouldn't want to arrive at, for the same reason why you can't teleport somone against their will - you would be very unhappy about teleporting into a wall, or onto the sun, or to the bottom of the ocean. And for that same reason, the hostage-taker cannot be teleported into prison. (But maybe you could teleport him into an unguarded bank vault... because sometimes it works if it's somewhere the person didn't know they wanted to be.) [Answer] John has the power to trigger the teleport on himself and anyone he touches, but where each person is teleported to depends on having a picture of the destination in their mind. Without an image of a destination they won't be teleported at all. This also opens up the possibility of being teleported to a random but familiar place (hostage thinks "I want to get out of here"). [Answer] ## Everyone can *almost* teleport Imagine that the average person has about 90% of the telekinetic skill needed to teleport. John has 110%. Below 100% per person, nothing happens; the mass is too large (and telefragmentation is forbidden). A willing person contributes 90% and John puts in 110%, resulting in 200%, enough to teleport two people. An unwilling person puts in 0%, and thus can't be moved. For fun, some people could have more or less skill, or more or less willingness; one person might be a near teleporter with 99%, and thus hardly a burden to John even if their twin comes along too; another might have only 50% and be unteleportable, or nigh on. Someone with severe depression might not be able to muster all their latent jump ability. Or a certain drug might enhance it temporarily. Maybe different degrees of unwillingness matter. Handwave as needed. [Answer] Teleporting is a three stage process: First John needs to put the part of his surrounding that he wants to teleport into his teleportation bubble. In the second step he needs to establish a mental connection to his destination. Only the third step is the actual teleportation. During the second step John is extremely vulnerable to his current surroundings as all his senses are turned towards the destination. This is usually no problem as this happens in less than a second. However it is only so quick as in Johns teleportation bubble the time runs faster. Thus a person being inside has about 7 minutes to burst the bubble or even attack John. The other person might still be transported unwillingly if they did not react in time. However John should rather not rely on this and strongly prefer willing passengers (or passengers weakened enough through accidents that they cannot do any harm while getting teleported to the hospital). [Answer] I think everyone here have overlooked an important point, which is that **by teleporting John gets tired**. The more mass he moves, and the further they go, the more exhausted he arrives. So let's examine the situation where we have a criminal with a gun holding hostage a bunch of people. For simplicity, suppose John was amongst them, so he doesn't even need to get there in advance. *Technically*, John could touch the criminal and teleport him to a jail (if there is a nearby one). *But John would arrive with the criminal*, which would immediately shot him point blank. Even without firearms, you should note that John arrives exhausted after every *jump*, and will need to rest for several hours before being able to teleport again. A lesson he learned very soon was that teleporting someone to a place they don't want to be, usually ends with them punching in the face a John too tired to even cover himself. The evaluation of the intentions of other people is not done by his power, but *by the teleporter himself*. That's why people who really don't want to be teleported aren't, but people who don't mind or want to be teleported can be. [Answer] # Quantum mechanics and observation Quantum mechanics is full with things that we don't understand. That means it's easy to bend into shapes that fit the narrative. We can see with the [double slit experiment](https://en.m.wikipedia.org/wiki/Double-slit_experiment) that things can change with an observation. In one way it's a wave, the other classic particles. Next we have Quantum tunneling. This is because of some uncertainty that a particle can 'teleport' short distances. This doesn't require energy and go 'through' obstacles as far as we can tell. Your teleportation can work the same. The teleporter makes themselves and any object or person uncertain. The teleporter does this in such a way that it initiates Quantum tunneling all at once, towards the location of her/his choosing. Now we start to bend the rules further. Observation in a certain way will make someone certain of their location. In this case, observing you do not want to teleport is enough to keep you at your place. If you do want to be teleported, your observation will allow the uncertainty, thus the Quantum tunneling. [Answer] Teleportation is an effect of mind and probably quantum related. Trying to teleport an unwilling sentient resulting in failure to teleport them would be a blocking effect of their unwilling mind on the quantum process. Knock them out to port. All the overreaching aspects of ‘breathing makes it fail’, or moving, etc. sound like the capricious and entirely subjective choices of a dungeon master on spell effects and best avoided. ]
[Question] [ For many battles when one side is obviously superior I observe that victors(bad side) almost never finish his enemy. For instance: * [Empire vs Rebels](https://youtu.be/PN_CP4SuoTU?t=331) * [Ori vs rest](https://www.youtube.com/watch?v=YkhZlccoI8c) The outcome of battle is similar, weaker side(good one from movies) is defeated but some ship survives(may be heavily damaged but still with life support). Is it part of "Shock and awe" doctrine to leave witnesses of power and break resistance? Or just is it nice for movies? What are other advantages of not destroying enemy entirely(maybe ambush for rescue)? [Answer] On a practical basis, allowing your enemies to surrender has several benefits: * It makes other enemies more likely to surrender in the future, reducing your losses. If you have to kill 100% of your opponents in every single battle, you will also take more casualties. If you have a reputation for accepting surrenders, people are more likely to consider that an option. * In some cultures you can ransom back captured enemies. At the very least, you can likely trade them for your own soldiers that have been captured. * If an agreement such as the [Geneva Convention](https://en.wikipedia.org/wiki/Geneva_Conventions) exists, you may be violating it by killing all of your enemies. That could cause other groups to ally against you. More importantly, however, *very few fights are actually that decisive*. Unless you can somehow force your opponent into a situation where they *can't* run away, most battles will end with a retreat and regroup. Once it becomes obvious that you're losing and the chance of victory is very small, the logical strategy is to go somewhere else and try again. So except in cases where one side has a fixed defensive point (a city or other installation), it's very rare for a situation like you describe to happen. [Answer] It's necessary to divide the discussion into two parts: real battles and literary battles. We'll start with real battles. Other than very small battles (a few dozen or so people) it's essentially impossible to kill *everybody* on the losing side. Battles are confusing, chaotic events, and spread over a large area. Furthermore, there is typically a wide range of competence among the participants, and a determined, very good combatant (or group of combatants) can generally find a soft spot in the other side. This will allow them to cut their way free. Furthermore, most large military forces contain light, fast units used for reconnaissance, and these scout units are unlikely to take part in the worst of the fighting, and will be well-situated to flee when the battle is lost. Also, unless the winning side has absolute superiority, they will be unable to completely surround the losers to prevent escapees. To do so invites overwhelming local attacks by the surrounded unit, as the surrounded unit takes on one small part of the other side, defeats it with small losses, and then moves on to the next one. This is called defeat in detail. And if one side does have such overwhelming superiority, the other side will probably do its best to avoid battle in the first place. Now, as to unreal battles. Umm. It's hard to figure out where to start. Cartoon battles don't have a whole lot of connection to reality, so it's entirely up to the writer to determine what happens. You do realize this, right? In the case of the links you provided, having survivors provides for story continuity, as the survivors go on to avenge the loss. Plus, of course, if the good guys are *all* killed off in the first scene it's hard to have the rest of the story. [Answer] The main advantage of not destroying the enemy utterly is that there generally is no benefit from utter destruction while there is a real cost from committing resources to it. For example, pursuing fleeing enemies means detaching a force to follow them which means the pursuing force will not be available for anything else. Unless you have an abundance of fast troops, this is usually bad use of resources. Fast troops are generally more useful for screening and reconnaissance and committing them to vanity projects will potentially leave you exposed to enemy stratagems that otherwise would have failed. A policy pursuing fleeing enemies also gives the enemy a trivially exploitable and predictable opportunity to lure the pursuing force into an ambush. Which is even worse use of resources. Similarly every enemy that flees or surrenders instead of being killed is one less opportunity for your forces to take casualties. Psychologically such "total kill" policy works two ways. It promotes desertion and lack of resistance, which is good and works well for fast campaigns. But if the fighting drags on, the campaign becomes prolonged, you will be fighting enemy that is committed to fighting to the death. This usually translates to high morale for them and high casualties for you. Manuals since ancient times have strongly advised to avoid situations where enemy can't escape for a good reason. So a "total kill" policy should always be targeted on only those cases where either making your potential opponents choose not to fight at all is a priority or you are already fighting fully committed enemies. Historical examples would be Mongols needing to minimize time consuming siege warfare to fully exploit their superior mobility or religious or ethnic warfare that might already extermination wars, anyway. Asymmetric warfare between superior occupying force and a resistance movement can sometimes devolve into this, if the occupation prioritizes scaring people into not supporting the resistance. But as this causes heavy collateral damage, it is rare unless the occupiers have lot more area under occupation than they can or want to control.Germany had such situation during the World War 2. One consideration is that the enemy soldiers are also resources with value and dead humans are usually nearly worthless or even have negative value as you need to commit forces to disposing of the bodies. The exception would be if the dead soldiers have value as food or trophies. But generally armies are too large for that value to remain worthwhile if you kill everyone. So this is only realistic for skirmishes or asymmetric warfare where the defeated force is small in relation to the victors. Generally almost all of the value of the captured soldiers is in their ability to work and they are used as forced labor or sold to slavery. There is also real political value in returning prisoners of war after the war or even exchanging or selling them back during it. This is true even if the "enemy" is supposed to not exist after the war. In that case you have supplanted the enemy and the value of enemy soldiers you did not kill is now **your** resource. These value considerations do apply to letting fleeing enemies get away, not just on what to do with captured enemies. If your best option is to let them go, why spend resources capturing them? From the viewpoint of military strategy you should also remember that the goal is usually to destroy the ability of the enemy force to oppose you, not to kill soldiers. As others have noted killing everyone is actually very difficult, so there is almost always several vastly easier methods to achieve your goals without killing everyone. The big exception in history is siege warfare, where you already may have the enemy surrounded and the fighting will likely get ugly and chaotic anyway. In such situations massacres have happened. I hope this actually contains an answer to the question. In any case it should be useful in giving some context. [Answer] In addition to Dan Smolinske's answers, which I think are spot on, leaving witnesses is also an essential part of information warfare. Anyone who has studied war knows that the perceptions of the civilian population is important for ensuring support of the military. Thus, the military provides a great deal of propaganda, which is always one sided. A survivor can tell a different story, and its hard to argue with an eye-witness. This can soften the resolve of the civilians. It can also soften the resolve of the military, if that individual is returned to duty, but that tends to be more difficult because the military tends to have more resolve to deal with. However, leaving a survivor leaves a little bit of unknown. The effect of the battle will be more widespread, and less in your control. If you are sufficiently superior, and really just want to finish squashing the worthless vermin so you can get back to your Croquet match, you may be willing to spend more energy to crush the vermin in a way that doesn't depend upon you observing their response to your survivors. If you find the vermin to be so unworthy that you don't even care to win the information game, why leave a survivor, just wipe them out. [Answer] Even in real battles where the one side was destroyed to the last man (think of the fate of the Spartan "300" in the battle of Thermopylae, the Texans at the Alamo or the French Foreign Legion troops at Camarón), enough people manage to escape in the confusion to bring the story back to their homes. As well, the victors will probably have a story to tell as well, for propaganda purposes. While a 100% casualty rate in warfare is very rare (we remember the 300, the Alamo and Camarón *because* they are unusual events), there are usually enough eye witnesses for both sides, including disengaged forces in the reserve or flanks, Non-combatants who are following the force or even journalists in the modern era, who will be able to piece together at least part of the story. As well, while a defeated force is usually bad for morale, the historical examples ended up stiffening the resolve of the survivors, most of whom took it upon themselves to either avenge the deaths, or become more determined to fight and fight well to prevent such a fate from happening to them as well... [Answer] Not really answering the question but many armies try to injure enemy soldiers rather than kill them, on the logic that an wounded soldier takes up more resources than a dead one. I have heard many cases of attacks designed to demoralize enemy where survivors are left, but for a NATO force it is not currently common practice. [Answer] Often desertion from battle was punishable by death. The commanders of the losing side will want to have an ordered retreat, where entire units of troops survive, and will actively work towards that goal when the battle is lost but not yet over. As commander of the winning side you want the enemy to make an ordered surrender or an unordered retreat where people flee disorderly, which makes it much easier to run them down, and the survivors may be unable to rejoin their army without facing severe penalties. In both of these cases you have survivors to spread the word but got rid of the enemy combatants. Even if you kill all enemies, in battles of tens of thousands it's incredibly likely that some will survive by feigning death and sneaking away in the night. The times where you'd let entire units flee is if you either cannot stop them easily or with low risk\*, if there are diplomatic reasons (sign of goodwill), or you are reasonably certain you won't have to face the troops again. Keep in mind even in the diplomatic case it's often better to capture and disarm the enemy, then release them, instead of just letting them retreat on their own. \*Stopping a retreating unit is hard if the commanders' attention is required in other places. Stopping a retreating unit is high risk if the terrain makes it possible that enemy reinforcements could lie in ambush. It's even harder and riskier if the enemy unit is still in good shape and can defend itself. [Answer] In medieval times persons of rank where clearly defined from the rank and file grunt with the idea that you were more valuable alive as a captor than dead (held for ransom). These prisoners were not imprisoned but often were treated accoring to their rank and kept in open custody. In today's world where snipers abound badges of rank are greatly subdued and hard to distinguish from even moderate distances. Another item of note was the pardoning of captured enemies with their promise not to fight this was practiced from at least the days of Caesar until the American Civil War. Current Military Codes (i.e. UCMJ) , specify that an officer cannot accept a pardon but must must continue to fight on. [Answer] This verse is about God showing other people why wicked people were destroyed, by allowing them to observe the character of survivors. Ezekiel 14:23 You will be consoled when you see their conduct and their actions, for you will know that I have done nothing in it without cause, declares the Sovereign LORD." NIV But, certainly, a more common motive for leaving or releasing survivors is to demoralize rather than "console". ]
[Question] [ Imagine a visiting alien accidentally spilled a bucket of inverse matter (a substance I made up just now) on the planet Earth and this stuff will annihilate with ordinary matter to produce neutrinos with perfect efficiency, erasing the earth. Feeling remorseful the alien 4D printed the Earth in its exact state just seconds before the destruction took place, atom by atom. **How can we possibly tell that we are a copy of the original?** Additional information: * Satellites and sensors on Earth were returned to that exact moment. * This only affects the region of space up to the orbit of the moon. * The irresponsible alien simply retreats silently leaving no trace of its presence and action. [Answer] > > Even the satellites and every sensors on Earth were returned to that exact moment and this only affects the entire region of space up to orbit of moon (...) > > > Everything above the Moon will seem to have changed position instantaneously in a very weird manner. All the signals picked up by the Deep Space Network will be coming from the wrong places. Solstices and equinoxes will happen at the wrong dates and times. We might not be able to figure whether we have been teleported or whether we are a copy, but this will be a discussion that's way more popular *dark matter vs. MOND*. [Answer] Even if the alien does not create a perfect copy of the quantum state, we will not know. First, 99.99% of all people (possibly more) couldn't tell anyway if the copy wasn't quantum perfect. As long as the copy is perfect within maybe millimeter scale or so (say pico if you will), few will *observe* it at all, of those only few will *notice*, and of those who do, most will do it away. Second, from inside a system, there is no way we could tell "truth" anyway. In order to notice that something has changed, we would have to have access to external information. That's true for every system. Luckily there's an entire universe around us, isn't there! While that solves the problem in theory, in practice things are much different. Easily observed, or *not that easily observed* details such as the sun being not in sync with every clock on the planet, or stars "jumping" in the sky, or deep space radio signals having a hitch will not do. Humans are excellent at denying truth, and they are even better at coming up with a plausible explanation when their beliefs are shaken. In fact, that's probably what humans are best at. I've recently had the opportunity to observe this on a person with ischemic stroke. That person was motorically 100% functional, but cognitively entirely dysfunct. He had his tablet computer in his hands and was typing random characters and approx. 200 emotes (whatever the onscreen keyboard creates when you keep tapping randomly) into the email program's `To:` field (no network access, mind you). The person was deeply convinced of knowing what he was doing, and it was an important task (without being able to tell what). A week and half later, that same person was, again, fully functional. Still, even today, he denies the externally observable truth, insisting on having done something orderly, and important (without being able to tell what). Is that man a liar? Well no. From his point of view, from what's stored inside his brain, that is indeed the exact truth. Even if you showed to him a video recording of what happened, then this couldn't be true. Because, well, that's *obviously not* what happened, the video must be fake. Remember the famous garbage-guy scene from the "Voyage Home" Star Trek movie: (strong wind, a garbage can gets flattened, a hatch opens *out of nowhere*, weird people come out of it, hatch closes and is gone) > > Did you see that?!! > > No. And neither did you, so shut up. > > > Worded differently, if your clock is wrong, then you should probably adjust it. If you just saw the stars jump in the sky, then you should igore it, or maybe see a neurologist. If the guy next do you saw the same thing, it's *folie à deux*. Or it was a reflection of, *something* that flew by. Weather balloon? If the government's clocks are all wrong, then some stupid bureaucrat fucked it up. Or the global, uh, Bilderberger, conspiracy did it so they can, I don't know, whatever they're doing. Control your mind, steal your underpants, whatever. And unluckily, the crazy explanation isn't even as unlikely as one would wish. For example, GPS being suddenly "wrong" is a thing that demonstrably happened during the Gulf wars. Aliens? Well no. Bush and Schwarzkopf. Occam's Razor applies in its mundane (wrongly quoted) form: *The simplest solution is always the correct one*. Many people go even further, and turn it into: *The least disturbing explanation is always the correct one*. So... if something is suddenly *definitively weird*, then the people observing it either made a mistake, or they're crazy. If there exist too many people worldwide having observed it, and hard, undeniable evidence exists so this solution can be ruled out, then alright, *something did happen*, but it was a perfectly normal natural phenomenon that we just don't understand yet. No way has Earth with everybody on it been duplicated by aliens. Because, hey, that is *just a crazy, stupid idea*. Being external controlled by aliens? Duplicated? Go see a psychiatrist. Whatever it was, it's most definitively something that happens *naturally* every few million years, we only just observed it for the first time, and we do not understand it yet. Some, whatever, interference shifting our space-time frame a bit. While we do not have an explanation at hand, we will work out a *perfectly normal, non-disturbing* explanation related to... black holes, or dark matter, or something. [Answer] You can't. Heraclitus, a Greek philosopher born in 544 b.c. said, “No man ever steps in the same river twice, for it's not the same river and he's not the same man.” Though the Nile is never the same Nile Ramses saw, we still call it the Nile. Replacement of molecules happens in every moment in almost every system, and we don't tell any difference. [Answer] Perhaps this helps? In one of the Star Trek (TOS) novels (I forget which one: either *Spock Must Die*, or *The Price of the Phoenix*), they make reference to an organization within the Federation vehemently against the use of transporters for people. The point was that transporters never *technically* "move" anything; they operate by destroying the item and rebuilding it elsewhere. The problem with moving people was whether or not the copy had a soul. Hence the organization to stop it, however small a group they were, were freaked out about having everyone who ever went through a transporter possibly having been killed on the spot the very first time they used it. So just as with this story, the issue in your case has to do with what "copy" means. In that discussion one of the Enterprise crew pointed out: "As Mr. Spock once said, *'A difference where there is no difference, is no difference.'* " ]
[Question] [ [![Free image from Pexels, https://www.pexels.com/photo/timelapse-photography-of-stars-at-night-169789/](https://i.stack.imgur.com/DO0l5.jpg)](https://i.stack.imgur.com/DO0l5.jpg) # Under what conditions would a planet's night sky look like this to the human eye? The angular speed of the stars relative to the planet would need to be high enough for the stars to blur into themselves. Is there a (realistic) way for such a planet to exist? I'm not sure how the *incredibly fast* rotation of said planet (compared to earth) would affect the objects on its surface. --- # EDIT Thanks to LSerni and all others for the in-depth answers to my question. What if, instead of the planet rotating faster on its own axis, the speed at which the planet orbited its star would be increased by a massive amount? Could mass of said star, the planet's distance to it and the speed at which it orbits the star be set in a way that allows for stars appearing as lines? The planets rotation around itself could in the reverse direction to allow for relatively longer day/night cycles. Or: Could an internally stable system rotate this fast in relation to the other stars? *I believe that this addition does not alter the original question's content. In case this edit violates any guidelines, please let me know, as I'm new to both WB and SE.* [Answer] > > Is there a (realistic) way for such a planet to exist? > > > # No. The minimum exposure time for such a photo is about 10 minutes (360 degrees in 24 hours means that to have 15-degree arcs you need one hour of exposure; five minutes will yield blurred arcs of less than three degrees). The scotopic retinal persistence (bright lights seen at night) has a relaxation time of about 1/10", slower than the normal which is around 1/25" but still too much. You would need to compress those 10 minutes (600 seconds) in one tenth of a second, which means a rotation *six thousand times faster than Earth's* - one revolution every 15 seconds approximately, or 4 rpm. At that speed, even if the planet is much smaller and denser than Earth, on the equator (let's say 3000 km radius) you get a centrifugal acceleration **in excess of fifty thousand G** (centripetal acceleration is proportional to the *square* of the rotation frequency. Six thousand times the speed gives you thirty-six million times the force; even dividing the radius by two leaves you with an eighteen million times increase). The planet would disintegrate almost instantly. You cannot simply increase persistence of vision by positing a *really* long scotopic decay alone, because we're dealing with a factor of six thousand; at that point, just moving your head would completely compromise your vision. You would need to move thousands of time slower. But this means that days will flash by, and you'd see the sky blazing on and off. So, you need also a perpetual night (at least in the inhabitable zone of the planet). You could get something like that, therefore, on a very small planet where humans lived in *slowed down time* (e.g. Charles Sheffield's *Sight of Proteus*, and [Between the Strokes of Night](https://en.wikipedia.org/wiki/Between_the_Strokes_of_Night) again by Charles Sheffield). If their "day" actually lasted sixteen years, they would see a 24-hour day's night sky like that. Of course you would need to have no day at all, so either make it very small and tidally locked to a very near, very dim star (or a black hole - e.g. in Greg Egan's *Incandescence*), or have it be a rogue planetoid far away from any star. The scenario would be halfway between Between the Strokes of Night and, perhaps, the backstory of Blish's *Surface Tension*: humans found themselves on a very low gravity, perpetually dark planet. There are some biological reactions available but energy gathering times are too long to sustain human life (the energy in a field of wheat requires one year's solar output and can feed X humans for one year. Lower the energy due to darkness, and X drops so low that you no longer have a population). So their solution is to cheat. By slowing perceived time using Sheffield's *S-Space* by a factor of six thousand, the bioengineered humans will receive six thousand times more light, and be able to see. And the sluggish semiorganic crops of the land will grow six thousand times faster, supplying the raw materials to produce everything else for a population that requires six thousand times less food and oxygen. Also, the negligible gravity of this asteroid is apparently multiplied (9.81 meters per second squared, but a *second* is now almost two hours) and - *handwaves quickly* - is now almost exactly Earth normal. # Edit: fast planet. > > What if, instead of the planet rotating faster on its own axis, the speed at which the planet orbited its star would be increased by a massive amount? Could mass of said star, the planet's distance to it and the speed at which it orbits the star be set in a way that allows for stars appearing as lines? > > > The rotation has still more or less the same speed - we need five degrees' worth of rotation to take place in less time than it takes the perceptual image to fade. The planet has to rotate very fast around its primary. This is along the lines of [**pulsar planets**](https://en.wikipedia.org/wiki/Pulsar_planet) (one example is [PSR\_J1719-1438 b](https://en.wikipedia.org/wiki/PSR_J1719-1438_b), aka the "Diamond Planet" - it's thought to be the compressed diamond core of a shattered star - now how cool is *that*?). In truth, any planet orbiting near enough a sufficiently massive object will do. The problem is that the planet needs to be even nearer and/or the star heavier than the pulsar case, which places the planet inside the accretion disk of a probable neutron star or black hole; indeed, this latter one is the exact scenario of Greg Egan's *Incandescence*. It is very doubtful that the overall conditions, primarily the radiation flux density, would allow people to stay in the open and look at the stars. But if they could and did, yes, they might see something like the image you seek. I strongly suspect that whatever they saw, it would manage to be even more mind-blowing. Parallel to the "axis of the heavens", they might see the [Blue Ghost](https://en.wikipedia.org/wiki/Astrophysical_jet) of Larry Niven's *Smoke Ring*. And all around, the [Highway of the Gods](http://aasnova.org/2016/03/16/where-a-neutron-stars-accretion-disk-ends/). [Answer] **Don't change the planet, change the biology.** Allow your planet dwellers to select [long exposure mode](https://en.wikipedia.org/wiki/Long-exposure_photography) for their eyes (perhaps an improved night vision thing). It would be useless most of the time, but if selectable by the person, they could see such an image. [Answer] In his [Orthogonal Trilogy](https://www.tor.com/2011/07/08/greg-egans-the-clockwork-rocket/) author/mathematician Greg Egan reimagines physics and a side effect is a night sky comparable to what you've asked. In his novels stars produce motion trails as they cross the sky because the speed of light is not constant: different wavelengths travel at different speeds, producing a red-blue streak that reveals the path of the star as the wavelengths reach the viewer at different times. Reinventing physics might be a bit more than you're asking for or prepared to implement. [Answer] To answer the question as asked: no, it is not possible for the sky to present to the human eye an image exactly like in the picture, simply because the human eye does not have a "shutter" to set sharp start and end times for the exposure. *If* the planet rotated very very quickly (see L.Serni's answer for the calculation of the rotation speed), *and* the planet's rotation axis was tilted with respect to the orbital plane, *and* the observer was near a pole (so that they would experience continuous dark skies), then they may observe something similar, that is, they would observe the stars as arcs; however, the arcs would not have the uniform luminance shown in the picture, but rather they would have a bright head and diminishing luminance towards the tail. The fatal problem is that the planet would need to rotate so fast that it would immediately break apart; not to mention that away from the poles any inhabitants would be thrown into outer space, together with any liquid water... Of course, you can imagine that the eyes of the inhabitants have incredibly long image decay times; but in this case their usefulness would be greatly diminished. [Answer] If there were some reason that meteors were coming into the atmosphere of the planet in a spiral, they might look like that, but very briefly for each streak: [![enter image description here](https://i.stack.imgur.com/dYOJJ.jpg)](https://i.stack.imgur.com/dYOJJ.jpg) The stars behind them would still be stationary points of light, however. [Answer] Well, pushing the limits of a fictional story, there could be a lot of phosphorous pollution in the upper atmosphere causing the effect. It would be a visual effect and the stars wouldn't actually be moving that fast. [Answer] If you could twist and/or rotate space-time in a fashion then you could have the rotational effects without tearing the planet apart itself. How you achieve that rotation is beyond known science and discovery, but non-flat spacetime is a very real aspect of physics, so it's not a huge leap to other manipulations, whether natural or artificial. If it helps, visualise a plastic ball floating on a drain in a large bathtub as it empties. The ball will spin with the water and rotate. Relative to the draining water the rotation is quite slow as the ball is spinning with the water but relative to the rest of the standing water in the tub the rotation may be much faster. [Answer] Sort of but it might require a huge kludge to get it working: **Use time dilation by putting your planet very close to huge black hole and put it on a fast orbit, but not too close that it's torn apart** > > The minimum exposure time for such a photo is about 10 minutes (360 degrees in 24 hours means that to have 15-degree arcs you need one hour of exposure; five minutes will yield blurred arcs of less than three degrees). > Now those > > > Now those 10 minutes of exposure can happen in the blink of an eye! Or rather your eye took 10 minutes to blink from an external reference point due to time dilation. Note that this isn't really a long exposure, and has more in common with fast motion blur Granted, for every blink of an eye 10 minutes outside the time dilation field have occurred, those stars aren't moving very fast they just look like they are. Conversely you appear to be moving very slowly to any remote observers ## Obstacles You're going to have to be very particular, for one, you don't want too large a planet, or to get too close, or your planet will suffer from tidal forces. This means volcanics, heat, and in the extreme case, ltierally being torn apart. Stars will also consequently appear blue shifted due to the time dilation effects. You may also have additional time dilation effects as the planet rotates, bringing you closer to the black hole. These effects must be small else the planet will tear itself apart. So we're probably looking at a small moon. The smaller the better, definately has volcanic and seismic activity of some kind, even if it's cryo volcanoes ( see Jovian moons in our own system ) You're also going to face issues with space travel, and it will be easier to fudge if you get rid of the day night cycle, any star that could provide daylight is either sucked into the blackhole, or orbiting, meaning days would last a long time and have inconsistent lengths. This planet will likely require a moon or be in some sort of binary formation to prevent it becoming tidally locked. You'll also need to be sure the blackhole has cleared its surroundings, a large accretion disc will obscur your view, and probably kill all life on the planet, if it doesn't destroy or pull the planet in Suffice to say life on this planet would be very uncomfortable ## Other Consequences From outside the system, your planet will appear to be in slow motion. Remember, there's no long exposure effect here, only fast moving stars. The appearance desired is granted via motion blur instead. This also means that the desired appearance of the stars will disappear in high frame rate footage, don't point any slow motion cameras at the sky [Answer] # Yes, But! Well, I'm going to stretch the question along the lines of Gary's answer and say: "If the humans evolved to live on a very low-light planet." Humans have a short visual persistence because our planet is very bright during the day. As you probably know, the ability to form images is directly proportional to the number of photons impinging your retinas. So under a bright sky, you get more than enough photons to see what is going on with only a very brief exposure. But on a moonless night, it may take you a while staring at something to gather enough photons to guess at what you are looking at. Optical telescopes and cameras can see much better than human eyes not only because they have gigantic light collectors, but also because they can collect photons over a very long time and form a single picture from them. If humans ended up on a planet with a dim star (or far from their star, so daytime was still dark), and little danger (few to no carnivores, not many natural hazards), then you could say they are pressured to adapt to the low light levels. # Backstory Maybe the humans crash-landed on the planet with minimal supplies and learned to live in harmony but without advanced technology. Or the humans could be ultra-ecological explorers that have a societal directive to colonize planets in the least disruptive way possible (i.e.: massive light pollution is strictly forbidden). Or, they could be protecting the planet as an astronomical preserve, with ideal conditions for building large telescopes without industrial light pollution. Perhaps all the flora on the planet subsist on geothermal energy, and there is too little energy for any fast-moving animals. As the humans slow down to the pace of the planet, the need for fast optics would decline. Visual persistence would increase, to gather more photons, and light would get smeared out as they moved, or sat still but the planet rotated. # Math Just kidding. I'm not going to do the math. I'll just point out that the stars in your picture are only smeared out over a dozen degrees or so, which is maybe 1 hour of exposure. If your planet is smaller/faster, you could plausibly reduce this to maybe 10 minutes of persistence. That's pretty huge compared to to the milliseconds of persistence of earth vision, but if your daytime is orders of magnitude darker, and there is no need for urgent action, this is one way to adapt. [Answer] What if everyone on the planet just won the "This is where our planet is located" lottery? Completely scientifically feasible (though hilariously unlikely), it might just be the case that they're viewing tightly packed strings of stars that just, by chance, happen to look like that when viewed from their night sky. Might be a few non-line stars, even, just most of them are that way, maybe as a particular result of how the universe was formed around it. [Answer] I wonder if you might be able to cheat. To get this kind of streaking from stars, you would need the planet to be spinning very fast - as others mention - since stars are so far away, and they won't really move in relation to the planet. But, you might be able to get some of the same effects from celestial objects that are much closer, since they wouldn't need to move nearly as much to give a larger apparent movement arc. You could probably get streaks that way, though they might not be quite so circular. I'd thought, if you had an asteroid belt in the next orbit over, you could have lots of little objects (visible through proximity). They could even be moving relatively fast in relation to the planet, in the opposite direction, which would help lower the speed needed to form streaks. Especially if whatever had caused the asteroid belt was relatively (on a planetary scale) recent, so the chunks were still moving at a (relatively) high speed. Alternately, if you had clouds of space debris from some planetary-timescale-recent event that were relatively close to the system, they would get pulled towards the star and might appear to elongate as the nearer parts get drawn in faster than the outermost, so that they would for a time appear as streaks against the night sky. In either case, you would still see star-specks in the night sky, they might be fainter or harder to see due to the brighter streaks (essentially light pollution), but they would be visible in places. And the streaks would almost certainly be across the sky parallel to its rotation, rather than rotating in a circular pattern as your original picture has it. [Answer] **If...** we can ignore the unimportant fact that everybody will be dead and torn to bits, then yes (at least I believe so, it will be hard to verify). All we need is the planet being sufficiently close to a black hole so gravitational time dilation becomes noticeable. If time passes slower from your point of view, then time in the remaining universe passes faster. While you will not see streaks due to your planet's rotation (it actually rotates slower!) you will see streaks because stars are not stationary themselves. And if you are slow, then oh heck, they move fast! The funny thing is that time passes slower for the emitted light as well, so light moves more slowly the closer it gets to you (or rather, the black hole), too. So, some of that slow light will yet have to arrive at your eyes while the star has already noticeably moved sideways, and you should have a nice streak effect. So basically, you need *Miller's planet* where one minute is what... 7 years on Earth? ]
[Question] [ I am trying to create "job" for a very small, specific sect of people. These people's bodies naturally generate and store an energy capable of creating temporal and physical discontinuities. Basically, they are capable of magic. Due to a physical incongruity (their eyes are bio-luminescent and have patterns) the general populace knows that magic exists. That being said people who can wield magic are very rare, plus govern themselves very strictly, so magic (on a local scale) is heard of once, maybe twice a year. Altogether there are about 9 million mages in a world population of 4.5 billion. **Edit:** Due to how the magic works (a system of symbols that given an effect and the specifics of where it is and how long it occurs for) it is all very combat oriented. So manual labor jobs or doctoring is kinda out of the question. **Edit:** Temporal distortions are very similar to the Artemis Fowl time stop and would require major preparation. The physical side of their magic allows for an impossible energy fluctuations (think fireball throwing) or introduction of objects stored in purely informational form (think summoning). **Edit:** Mages police themselves because something like a sniper, etc. would kill them easily (when they aren't expecting the shot), and if people feared them, the government would take measures to eliminate them. The entire story (I hope) will be based on a singular group of islands about the size of Japan (the entire world is islands so wherever they go it will be island-y feel). The world has had enough time to advance to 21st century technology (of course aquatic tech is much further ahead while land-based travel is slightly behind). **There are also monsters** that can interact with mages, people that deal with magic on a regular basis, and inanimate objects. Mundanes can't see, feel, smell, hear, or taste these creatures. # The Question: What are conceivable jobs for a mage to hold? (For the sake of convenience money is no issue.) I am simply looking for a way for the main character to "play" with other mages. [Answer] # Celebrity chef Mages are fairly rare, so rich folks looking for the ultimate "Unique" experience would flock to mage-prepared food (and the mage could charge quite a bit for the experience). That being said, most of the food could be prepared as normal, with a few fireball-charbroiled steaks to add that "magic" flair. Imagine yourself seated at the fanciest of fancy restaurants, waiters flitting about with black bowties adorning their glowing robes. A hush comes over the chittering crowd as a handsome 30-something chef carts a large covered dish to the center of the room. Your dining acquaintances murmur "He doesn't look like a **real** wizard." Suddenly, fireworks erupt from the cart as the chef opens his eyes to reveal the glow that dispels all question of their wizardly status. The cover is pulled off to reveal a pile of blood-raw steaks. Audible gasps come from the audience as they begin to float up of their own accord. All lights are cut, save for a single spotlight on the wizard. He stands tall, and with a shout of "ABRACARUMBA!" bolts of fire flash from his hands, flying through the steaks and searing them to a perfect [Pittsburg Rare](http://en.wikipedia.org/wiki/Pittsburgh_rare). [Answer] Power generation, in secret, would be a reliable cost-effective, source of income for the "mages' guild". "You want to stop being stared or laughed at outside? Staying here in our protected family is easy. Every month you have a shift. Just cast fire on that boiler for a while, if you can cast second level, lightning on the anode over there. What you do in the rest of your month is up to you. Someone will come relive you in a half hour." It would have a low risk of death and almost no exposure to mundanes, which makes it perfect for caring for the financial needs a possibly unpopular class of people. It is also decentralized and eventually, indispensable. "I agree, Mr President, they are exceedingly dangerous, they can't be unarmed, they don't follow our rules, but if we want to keep the lights on..." [Answer] **Ultimate Mixed Martial Arts Fighter** Think about how popular boxing and now MMA have become - they're incredibly popular sports. Fighting is a big business. Now we're adding magic on top of that. Mages are faster, stronger, more resilient and flashier. They can fight longer and realistically do crazy things that bring in the ratings. A mage-only MMA federation could be a huge business, with the top performers being megastars. [Answer] So they self police, which means there is something of a Mages Guild. The main point of a mages guild is to make sure that only people inside of the guild do magic, and only when they are supposed to; or you could say the point of the mages guild is to make sure that magic doesn't happen without reason. So why not make that reason money? This is especially true with the magic being combat oriented. It could go a few ways. **Mercenary Work:** "Give us money and we'll do a job for you, make a problem go away." **Protection:** "Give us money and we'll keep you safe." **Protection:** "This is a nice city you have here. It would be a shame if something were to happen to it." **Protection:** "That rogue mage that has been bugging you is no longer a problem, here's our bill." So a really good job for a mage in a mages guild that wants to "play" with other mages is elite mage police. He wouldn't bother with anything so common as crime, or murder. His job would be investigating and apprehending anyone that does magic outside the guild. First to try to recrute them into the guild, and if that failed then to make sure they never do magic again. [Answer] 9 million mages in a world with a population of 4.5 billion means that 1 in 500 people is a wizard. The greater Los Angeles area would have somewhere around 32,000. Even my modest home town of Wichita, KS would have over 700. That would make the community of mages a fairly major force, with their numbers rivaling those of doctors and police officers. Most people are probably acquainted with at least one, and many people know several. Given the numbers and the assumption that the magic is largely combat-oriented, I would expect that the vast majority of mages are employed as peace officers or soldiers. [Answer] "Live, Die, Repeat: Edge of Tomorrow" - this movie made science-fiction use of limited time travel. Even in a "freakishly combat-oriented" world, there are other jobs. **Pit boss at casino**. When mages can see the future, roulette is a losing game for the house, so mages have to work for the casinos to keep out fortune tellers. The same goes for pro sports. **Security**. When mages can teleport or walk through walls or watever you mean by "physical discontinuities", you need bank guards, military guards, science lab guards, etc. who can anticipate and counter these types of assault. **Gunners and spotters**. In the "Lie, Die, Repeat" fashion, you don't need computers to guide your munitions. The gunner fires, the spotter "sees" if the artillery shell hit its target, if it misses, he calls a correction to the gunner who backs up time a few seconds, adjusts the sights and fires the same shell again. Of course the defenders can fire their interceptors and hit a bullet with a bullet. The limit is how much magic food they have on hand - because time travel makes you hungry. The frequent bathroom breaks that time-shifters have to take is also a logistics problem. [Answer] I think there would be a role around gambling- minor physical discontinuities are precisely the kind of thing that would allow one to bias the game in favour of the house or in favour of the gambler, so this would be an area where an arms-race could easily arise. Alternately perhaps gambling becomes unpopular in this setting or the casinos employ others of the ephemeral creatures mentioned to keep an eye out for magical intervention. The ability to hold time and move through the held moment would have all kinds of useful effects particularly in rescue or security situations - a policeman who can pause time and move through moving environmental factors or a fireman who can walk through fire ( assuming that flames are energetically "paused" by the time freeze ) would be able to potentially be able to help a lot of people. Likewise a doctor who could pause time for a patient during surgery and effectively sew up wounds instantaneously would be able to save many lives. Even if their abilities are destructive in nature, this could still be very surgically valuable. [Answer] The only possible answer is actually quite simple and completely contrary to your line of thinking and the other existing answers. First, let's really think about this situation. If the mages are seen to be powerful and dangerous, the numerically overwhelming rest of the population would rise against the mages in a witch hunt and exterminate them. History has shown us what happens to those with purported magical powers. And if the mages fought back, they would simply prove their dangerousness and be hunted even more vigorously. If the powers of the mages would be useful, governments and criminal organizations would force them into their service (or exterminate them). The only possible path of survival and freedom for the mages is to keep their powers secret, live inconspicuously, and **work in random common jobs**. That their eye color differs from that of other people is no more relevant than that the eye color of green eyed persons differs from that of others. For all we know, the green eyed persons of our world could secretly be mages. (And of course you know that at times green eyed persons were in fact believed to be witches.) If the mages keep their magic secret, their bioluminescent eyes will be thought to be no more than a strange evolutionary coincidence. [Answer] Perhaps the mages can hold various jobs throughout society. (high level government, military, science, local law, etc) They would monitor and or interact with the monsters providing a buffer/protection for the mundanes or monsters as deemed. An example would the watchers in the highlander series but could influence outcomes if that is what you want to do. [Answer] **Diving** Combat skills become useful to dive to pretty crazy depths without any need for huge submarines and bulky suits that protect from pressure and dangers alike. **Flying** Where aerial development might be lagging slightly behind (in a world with no land to incitate development like it has in ours, there is no real reason to develop travel in the air when water makes up for open trade routes etc...). Monsters may also be airborne, again, combat skills useful. Or they might all be air pirates, holding the monopoly on air travel, and keeping the lowly non magic users to the waters and land below. **Notes** * I'd basically see them mostly as explorers. Exploration (especially at sea) is dangerous and in a world where there are only islands and sea, there is a LOT to explore. * Let's not forget space. If tech has reached our current stage, and that magic exists, what would be the implications there. Would it make it easier? * Conflicts/Wars [Answer] Manual labor work is certainly not out of the question. If you can apply a lot of work (where work is force times distance) to a dragon in combat, you can also apply work to a mine. Many manual labor jobs that involve breaking things up or moving things are certainly in question. If you have a spell that would forceably knock back a dragon, you could also use that force to push a mine cart. If you can knock off a dragon scale, you can knock off a piece of ore. It might take time to train your skills to be utilized in a manufacturing capacity instead of combative, but the mechanics are very much the same. But this would be for low level mages who simply need to hone their skills or perhaps who have given up war. Most mages would definitely be in security of some kind. The most powerful mages, having led battles and such, would probably be in consulting (more affectionately known as Royal Wizard or Court Sorcerer, usually). There also would need to be a very steady supply of magical reagents, meaning experts in logistics would be necessary. It's likely these wizards would get jobs in the procurement and distribution of these reagents. Lastly, as the old saying goes, those who can't do, teach. To keep the influx of wizards there would need to be a place to train these wizards. I'm thinking a bit older than something like Hogwarts (which would only be for the incredibly gifted to train them from near birth in the wizarding ways), such that going into magic would be little different than going into any other profession. [Answer] They would be technical specialists in "normal" fields. Realistically, society would evolve to use these mages in more-or-less everyday life. If it's a world full of islands, fishing would be important. Perhaps a trawler fleet would leave port with a one or more mages. They travel to their fishing grounds, chum the sea to attract the fish, and the mage(s) create large pressure waves in the water - for examples they create a void which then suddenly closes. This is, in effect, what an explosion does: it creates an over-pressure wave that expands spherically around it. Now you have dynamite fishing, powered by magic. The trawler fleet collects the fish, and everyone profits. Similarly, if there are whaling fleets, one of your mages could freeze time, take a careful shot, and ensure that the fleet harpoons its targets on the first time, every shot. Trauma doctor is probably a perfect job for someone with the powers you mention: the mage could stop time to prevent someone from bleeding out. If it can only be done rarely, perhaps this mage does not practice as a doctor, but instead assists only with tricky surgeries or acts as an on-call EMS tech for a group of powerful people. Perhaps defensive abilities enable a mage to protect others from high heat - they assist in emergency repairs on critical industrial infrastructure - blast furnaces, boilers, high power lines, etc. (shipbuilding will be critical to your island-world.) These people are going to have to work for a living - if they are all so rich that working is optional, their parasitic drag is might wreck the world economy. At the very least, it would be a source of powerful aggravation to the 'normal' folk. So give them jobs that play to their strengths. They are the key players at specific points in critical operations. The rest of the time they prepare, practice, store up power, or whatever your story dictates. [Answer] Hot-Air Balloon Pilots and Locomotive Engineers Their powers of combustion could thep the hot-air balloon game up to a while new level. Also it would eliminate the need for coal in steam-engine locomotives. [Answer] How does your society see magicians? Are ordinary people scared of them? As magic is mainly combat orientated, are they seen as weapons? You should consider that there could be some sort of social divide between magicians and non-magicians. If so then can they easily fit into society? I would read some material that is based on these types of issues, like the light novel 'Mahouka Koukou no Rettousei'. How do your magicians wish to be seen by society? Do they wish to fritter they lives away performing magic as entertainment? Do they wish to give back to society in some way? Do they wish to be respected? Magicians are just people. The jobs that they choose should just align up with their ambitions. Unless society only allows them to have certain jobs. People are foolish are scared easily after all. [Answer] First of all, I refer you to [the thoughts of prolific magic system maker and author Brandon Sanderson](http://coppermind.net/wiki/Sanderson's_Laws_of_Magic). For my own part, I would strongly disagree with any magic system that "how the magic works it is all very combat oriented". Any violence comes from some kind of force or energy. If force and/or energy can be controlled, it can be bent to any imaginable purpose. In my experience, the more rule-oriented you make your magic, the more clever things you can make it do (*[Dresden Files](http://en.wikipedia.org/wiki/The_Dresden_Files)*). But the more mystical and handwavy your magic is, the rarer and more deus ex machina-ish it has to be. A society with advanced technology would have science, more specifically, the scientific method. Eventually someone would come along and experiment with it and try to beat his magic sword into a magic plowshare. As for jobs, most similar societies I have read in other works will usually have the mage just, doing magic on request. > > Hey mage, send wind to fill my sails. > > Hey mage, put an illusion on my scarecrow making it terrifying to wolves, deer, etc. > > Hey mage, will you make an enchanted thing that does x? > > > I am usually very happy to see enchanting in any magic system I read, it turns magic into an almost limitlessly useful commodity. Honestly you can make it do whatever you want as long as you are consistent. But I cannot stress enough, making ALL MAGIC "mostly combat oriented" is a bad idea, and when thought about logically, almost always not true. You've seen that already in that (ridiculously awesome) answer about magic chefs. If you want more specific solutions, you need to invent and post a more detailed magic system. [Answer] I think there would be people who would pay a lot of money for the service of a magician. Not only for protection, but also a symbol of status. So I think they would serve the wealthy people a some sort of personal assistent using their magic not only tot protect, but also to advice their employer. Maybe even use their magic as a means of amusement for their employer and his entourage. [Answer] I would expect that most of your mages would hold jobs that have little or nothing to do with their magic, but which interest them. They would use their magic in their off-hours, for recreation. You might compare it to someone who does bleeding-edge technology for a living, but outside working hours goes in for rather intense physical stuff like martial arts. [Answer] You really need to provide more details as to what a mage can do. Assuming teleportation that's not subject to conservation laws: NASA would love them. You're looking at a few thousand dollars a pound to LEO. Lacking any idea of how (or if) your teleportation works I'll take Greater Teleportation from the Pathfinder RPG to work with: A caster barely able to do this and of average strength can port close to a ton to orbit (I'm assuming some weightlifters as assistants and Bull's Strength for everybody) split between 5 packages. While that won't be enough to lift any substantial satellite it certainly can lift the fuel for the satellite--use a rocket to bring the satellite up with empty tanks, fill the tanks at a space station and then it heads off into deep space. If he charged a million dollars for this service he would have the orbital industry clamoring to hand him money and would have no problem clearing over $100 million/year. ]
[Question] [ I'm looking to write a story where the world is a lot of islands separated by rather small water expanses (about the width of the Mediterranean or maybe that and a half) and I am struggling to find a reason to have a guild control travel, a bit like in Dune with space travel. Essentially, I'm looking to bring the difficulty of space travel from Star Wars or Dune into a world that is ocean-based. My initial thought was to have it be very expensive, so some kind of mercantile aspect needed to be part of each travel, but it seems difficult to explain. The world I am looking at is somewhat post-apocalyptic. After some disaster in a modern-ish (maybe 1950s) tech level made living difficult, the contact of the planet with some kind of liquid raised the ocean level by several hundred metres and only very few survived. So technology is at a rather weird point, and magic is a thing in that world so any kind of magical navigation would be welcome, but this would not necessarily mean that regular navigation is impossible. I had considered making the liquid that raised the ocean level be something other than water but it would also affect the rest of the world as if it were poison it would get on land and poison that too, and making it acidic seems difficult considering that islands need to continue existing… Any ideas on how to give that strong barrier feel requiring specialised help without actually putting things in space? [Answer] # Massive sea snakes You can have a species of sea serpents that are ~50 ft long and attack ships thinking they are whales, since they live below where the whales swim they mistake the ships for the bellies of whales and attack them The merchant guild can have any one of the following: * magicians that cast wards around the ships that essentially repel the snakes (these don't need to be magical, you can just have some kind of chemical do it if you prefer not using magic) * expensive submarines that can a) see the snakes coming and warn the ships above and b) potentially attack and drive off / kill the predators with their powerful technology. [Answer] # Sailing is risky and requires lots of knowledge Just take a page from history. During the age of sail, specially during its first decades, explorers such as Columbus, Cabral, Magellan etc. had a hell of a bad time navigating the Atlantic. A major reason why they got so filthy rich was because sailing was a high-risk activity with large returns. Sailing itself is not easy, specially with large vessels. For long distances, piloting knowledge is not enough - you need to plan for the currents and winds you'll face. Make a mistake, and you either bring too few supplies and die for need of them, or carry too many supplies which slow you down and become a logistics problem. Now imagine trying to plan for those without knowing where the currents and winds will take you, and without knowing how strong they are. Magellan and his crew nearly died of starvation when crossing the Pacific because of that. Having good maps changes everything. Around the 1500's the Portuguese had a practical monopoly on marine trade with the Indies. They had been compiling maps of currents, winds, sandbanks and routes for centuries, but they kept those secret. Then by the end of the 16th century a Dutch dude called [Jan Huyghen van Linschoten](https://en.wikipedia.org/wiki/Jan_Huyghen_van_Linschoten) stole and published those. That had an impact in the 17th century orders of magnitude larger than Wikileaks had in our own time: > > He is credited with publishing in Europe important classified information about Asian trade and navigation that was hidden by the Portuguese. In 1596 he published a book, *Itinerario* (later published as an English edition as *Discours of Voyages into Ye East & West Indies*) which graphically displayed for the first time in Europe detailed maps of voyages to the East Indies, particularly India. During his stay in Goa, Jan Huygen van Linschoten meticulously copied the top-secret charts page-by-page. Even more crucially, Jan Huygen van Linschoten provided nautical data like currents, deeps, islands and sandbanks, which was absolutely vital for safe navigation, along with coastal depictions to guide the way. The publication of the navigational routes enabled the passage to the East Indies to be opened to trading by the Dutch, French and the English. As a consequence, The Dutch East India Company and British East India Company would break the 16th-century monopoly enjoyed by the Portuguese on trade with the East Indies. > > > Seriously. You all would be fluent in Portuguese rather than English now if it wasn't for van Linschoten. Your world can have its own Portugal, maintaining a monopoly on marine trade by maintaining a monopoly on knowledge. --- Edit: maps are not the only secret they could keep. [user3445853](https://worldbuilding.stackexchange.com/users/30075/user3445853) made this comment: > > The Dutch found the secret to preserving herring in a tasty fashion ("matjes/maatjes herring": remove all intestines except pancreas and pickle in a light brine --- pancreatic enzymes break down various structures in a tasty and stable way), and succeeded in keeping it secret for 300years (from just before 1400), selling the swedes and germans fish caught in their own waters and getting rich. This secret ANY uneducated deckhand could steal and sell, but they didn't succeed [easier steal than a detailed map set!]. So the maritime brotherhood CAN guard a secret. > > > This is specially interesting because many deaths on sea were caused by scurvy. Just so you know, when you've had scurvy for a while and you're still malnourished, every single scar you have in your body starts bleeding and your teeth start to fall. So in your world, people can either pay the guild fairly and eat preserved food during their travels, or they can venture on their own not knowing where the wind blows, the directions of currents, and to add insult to injury they will only have biscuits, crackers and rats to eat. [Answer] # Navigation. The sea is almost always covered in fog or heavy haze, making navigation by stars and sun a bit problematic. And ever since the partial Magnetic Reversal (what done in the real civilization!), magnetic compasses just argue with each other, and point to the nearest horseshoe. The Navigator's Guild knows some dark secret to keeping your orientation and knowing your position on the water, but it is a dark and jealously guarded mystery. (It's actually just simple old Gyrocompasses for location and direction, and a very very good store of maps including currents, but don't tell anyone!) [Answer] The oceans are now not very deep. Deep enough that you couldn't walk through them, but not deep enough to submerge all the rocks that now poke out the water. This makes sailing dangerous as almost any instance you could be knocked into a rock and get a hole in your boat. Depending how post apocalyptic you want, these "rocks" could be the remains of the buildings of the previous civilization. I'm not sure I'd want to try an sail a boat though the flooded remains of major city, where all your seeing is the very tops of tall buildings, and there could easily be buildings just below the surface you can't see. [Answer] Hostile intelligences. Such things are the plot of at least two books I've read in the past... intelligent organisms, alien or otherwise, take exception to human activity in the oceans and take steps to destroy human shipping and economic exploitation of the seas, extending as far as assaults on dry land by suitably engineered organisms. In one of the books the intelligences used nuclear-powered heating devices to attack the ice caps, in the other seabed clathrate deposits were disrupted to trigger an underwater landslide which in turn caused a massive surface tsunami. In one story the intelligences were apparently attacked and killed with a novel weapon, but in the other an uneasy truce arose at the very end. That sort of state of affairs seems like it could also arise in your world, with only the guild having made the appropriate overtures to the dwellers in the deep. Intrusions into the sea by non-guild ships might irritate the dwellers who may impose sanctions upon the guild (to encourage humans to police their own affairs), to take action on the treaty-breakers by sinking their ships or worse, to attack the landmasses the intruding ships came from. The latter might make for an interesting dynamic where no-one other than the guild has seafront settlements, because no-one else wants to find themselves swept away by a freak wave or more unpleasant *things* crawling up steathily out of the sea at night... (for those of you who might be interested in what the books are, and don't care about the spoilery nature of the text above, here you go) > > *The Swarm*, by Frank Schätzing, and *The Kraken Wakes* by John Wyndham. The latter is much shorter than the former, if you were thinking of hunting either of them down. > > > [Answer] **Zero Wind** ...means you'd have to *row* (assuming engines are not available), and there's a practical limit to how far you can reasonably get. [Answer] ### Your disaster put enough dust in orbit to turn the night sky pitch black You can navigate during the day by using the time and the angle to the sun to get bearing and location. You can use this for short distance travel of duration less than 1 day. However at night, it's pitch black. No stars. No moon. Nothing to navigate by. You can not get your position accurately for 50% of the time. Combine this with some magnetic reefs that make compasses unreliable, deep oceans where it's impossible to drop anchor and wait out the night, and uneven prevailing winds that can subtly turn you, and nobody will be able to cross the water until they develop speed boats that can do the crossing in one day, or flight. [Answer] ## Attack the sails themselves by Mothra OK, maybe not Mothra, but having a new mutation of moths that absolutely loves to eat the cloth used to make sails when they are salty, i.e. as soon as you start using them. With loss of the ability to make canvas out of Dacron, etc. only organic material remain somewhat practical (relatively inexpensive and functional). However, if you go through a dozen sets of canvas during a short voyage, it will raise the materials and labor cost and reduce cargo capacity considerably. This would be a nice variation in that fresh-water sailing could be cheap when ocean sailing is not. Clothing that gets sweaty would be a problem too. The controlling guild could simply be one that basically had a monopoly status on making the sails that could afford to drive competitors out of business. [Answer] There are a lot of closely spaced reefs which require careful navigation. Add to this unpredictable weather events which make the seas very choppy and hazardous. With so few people remaining, no-one has the ability to navigate by celestial or solar means. Take some ideas from [Jason](https://en.wikipedia.org/wiki/Jason) and the Argonauts and have something similar to Sirens trying to draw in unwary sailors so their vessels and cargoes can be stolen and any passengers and crew can be taken in slavery. Less dangerous waterways could be controlled by "nobles" or despots who apply tolls for safe passage through such waterways forcing some people to avoid them and use more dangerous routes. Currents in narrow waterways can be very treacherous. [Answer] # Shortages of raw materials For most of human history, navigation by sea required specific raw materials, mainly wood (and lots of it), but also hemp, tar etc. Planks can be cut from shorter trees (and even these need to be straight), but masts really require very tall trees. England's supremacy at sea in the Age of Sail came with [deforestation of large parts of the country](https://christian-watson.com/deforestation-in-britain/), so much that timber had to be procured in the colonies. One of the main tasks of the Royal Navy during the Napoleonic Wars was to keep the sea lanes into the Baltic open, where many of the indispensable raw materials were procured. Conversely, [*USS Constitution*](https://en.wikipedia.org/wiki/USS_Constitution)'s ability to shrug off British broadsides was due in part to her being built of extremely dense [southern live oak](https://en.wikipedia.org/wiki/Quercus_virginiana) (harvesting which required a different kind of raw materials, i.e., slaves - apparently conditions were so appalling that free workers would not stay on). Your guild may have exclusive access to very specific necessary raw materials, like a carefully husbanded old forest on certain islands. Safeguarding this access from greedy interlopers would make for interesting plots. [Answer] Most of your people suffer from extreme agoraphobia. Not just in the "afraid of open spaces" sense, which is the most obvious aspect of agoraphobia. Also the additional aspects of the condition: fear of getting outside of reach of other people that can help you if there is a problem and the fear of being in a place from which you can't reach safety. This is not so much a problem on land. And the agoraphobia has become ingrained in the culture, so most people don't even realize they have this problem. But being on a small vessel in the middle of the wide open sea... That hits all the wrong triggers. A very short crossing to a nearby island might be doable, or coastal fishing within sight of land, but further out... Some people will be naturally immune to the condition. They can be open sea sailors, but everyone else thinks they are either unspeakable brave or totally crazy (or both). This will greatly limit sea-travel. Only if there is a strong need for sea-travel (like the shipping of essential trade goods) it will be viable to undertake a journey. Real sailors will be wealthy men as their services are in high demand, but there is only a very limited number of people that can do the job. [Answer] **No ocean going boats.** 1600 km is a good distance. You would need a motor, or a sail. The guild makes the rounds and looks at boats. If there is a sail or a mast, or a rudder, the boat is confiscated and the owners are punished. Informers receive a bounty if they report the owner of a sailboat. The only allowed boats are oar powered and rudderless and people use those to fish short distances offshore or to make trips around their own island. Oar power is not enough to cross the mediterranean. The guild has sailboats and will charter trips for people who want to go distances. They will also intercept boats at sea in violation of their rules. Smugglers and rule breakers complete the start and finish of their trips at night, waiting out the days in camouflaged boats in the open ocean where they are less likely to be detected. On land, they have special disguised ports where they put in and hide their ships. [Answer] Space is inherently hostile -- we humans can't go out into it without full body protections from radiation and the lack of, well, much of anything that is out there. It's mindbogglingly large distances between solar systems that may or may not have anything worth while. To bring that experience into a terrestrial world will require some translation as even if the boat sinks and we are stranded on the water, we can live for a while at least, enabling a chance at rescue. ## New Specialized Knowledge Sailing in this new and more dangerous world is not just a matter of wind and water. The magic in your world interacts with the world not necessarily in a hostile way, but in a harsh and uncaring way. Also not fully predictable. ### Magical Knowledge Navigation in this new world is ma mix of traditional navigation as well as some manner of magical-based skill set. It could be a specific set of spells kept secret by the guild that makes long-distance travel much easier (or even just possible). Given the lack of population, but higher technology, it could be that these long-distance mariners are a guild so that their specialized skills can be passed from master to apprentice. That they control all long distance travel by doing this is a bonus feature. A sense for the currents of magic are just as critical as the sense for the winds and the waves, and for how your vessel feels in the wide open. How to guide your vessel through the metaphysical currents of magic can and will save your life. Of note, I'm trying to not specify a particular magical method of navigating as the type or style of magic was not mentioned, just that it was there. ### Updated Mundane Knowledge To borrow from The Square-Cube Law's answer, the new things to know about the high seas are kept a secret from the world at large to preserve their monopoly on the information. While everybody might know that the local kraken lives in Kraken Cove, few know that a mana current in the ocean between two islands hundreds of kilometers apart can wear a ship down to dust in minutes without the correct preparations. Shipbuilding might now need some manner of magic rituals to help imbue the ship's hull with protection from the harsh world, not unlike radiation shielding that we will almost certainly need for long-distance space travel. The people that developed this desire strongly to keep this a secret. ### General Knowledge For short trips between close islands and for fishing, what we have or can cobble together from what was left after the apocalypse will work. If there is a peril near an island, you can be sure that the locals will learn of it and learn to work around it. They will have the technology to log it and to keep good records. In essence, the islands and the bits of water around them are your solar system equivalents. ## The Sky's The Limit A minor frame challenge, but if you are not set on sailing in the waters, then how about the skies? If you are looking at 50's tech, then while jet planes and aircraft as we know them might not be a thing yet, airships definitely were something achievable. If I recall history correctly, the Hindenburg disaster spelled the end of an era for them in the travel department, and I know that was the 1930's Like above, your guild could control travel by controlling how to create airships. The lifting gas may be different, or it might be some manner of secret spell or alchemy that they keep hidden to secure their aerial monopoly. Any of the sailing tropes and ideas can still apply to zeppelins, and now you have the real possibility of crashing into some very unfriendly waters. [Answer] ### tl;dr A very weak magnetic field requires highly specialized navigational tools that can drive navigators into insanity. Some very few navigators (a guild) are able to withstand these side effects and navigate the oceans. This can even raise the question; if you end up in the wrong part of the world, was it because of weather, changing currents, bad luck, or is your navigator, although a member of the navigation guild, starting to lose his/her mind after all? ### Some details: A shift in the magnetic field so that it's near impossible to navigate by compasses. In order for compasses to work, you'll need to enable compass needles to move and indicate direction in a near friction-less device. Perhaps an orb the size of a fist in which magic or new technology cancels gravity. You could even build on the historic application of [mercury](https://www.hakaimagazine.com/article-short/dark-side-lighthouses/) in light-houses to create such a friction-less device. > > In the 18th and 19th centuries, the lens was usually set on wheels or > bearings and attached to clockworks, which the keeper would > periodically wind. In the 1890s, some keepers began floating their > lenses in liquid mercury. The lens’s metal base spun more easily in > the mercury, which helped the light rotate faster with less frequent > winding. > > > And also: > > Modern scholars have wondered if mercury, not isolation, was behind > reports of lighthouse keepers behaving erratically or losing sanity, > since chronic mercury poisoning causes confusion, depression, and > hallucinations. > > > What could make a guild in your world special, could be the ability to withstand the negative effects of operating, *not* light-house, but compasses, that needed mercury or another material / magic/ technology to function. The change in gravitational field could also be linked to the rising ocean levels in your world. [Answer] **The islands move and have no fixed position** If the island were capable of motions, it would be difficult to sail, since you have no certainty if and when you will be able to find a new harbour (or if after a pair of days you will be able to come b ack to the safety of your home port). Even more, it would also be very difficult to reach a particular destination. You could add to this effect a lack of fish in the sea (maybe there is a lot of krill, but in the same event that flooded the world, fish became extinct), which would make traveling by ship even more risky, since the crew would be completely reliant on the scores of the ship for food (more food to load on the ship would mean less cargo and less fresh water). Luckily thanks to magic, some gifted individuals can "sense" the presence of the islands (they're called Goal Perceiver Shamans, or GPS'), which means that every crew would need one of these navigators (certified by a guild) to lead them toward the islands. Also, there is a hierarchy among these GPS', since the most valued ones can sense the location of an island from farther, or can figure the location of a specific island (rather than any island). For the reason why the islands would move: * Well, magic (which is the reason why GPS' can sense their locations) * They're basically floating platforms and move along the sea current, maybe a kind of natural conformation or a particular kind of coral reef; Sea current are very irregular, so it is difficult to predict the position of an island in the future * Giant turtles (which would make their path more erratic than a simple floating island, whose path along sea currents could somehow be predicted) * They were huge platform built during the flood event to save the most people, and their origin has been forgotten since then. They are engine-moved (powered by still not exausted nuclear reactors) which the reason why they move in an unpredictable way; in addiction, the background radiation of the engines is what in reality allows GPS' to perceive the presence of an island [Answer] **[Elvers](https://multifiles.pressherald.com/uploads/sites/4/2015/06/649500_609895_elveres0002.jpg)**. The interstellar contacts of your radio operators and mages brought the attention of the Great Eels, who blasted away from their previous planet on columns of nuclear fire. They formed a great Ball hundreds of miles across to weather the crossing of space. They dispersed and rained onto every part of your planet's ocean, which they sensed from space, for forty days and forty nights, until the entire level of the sea was raised. A very few, the Supreme Eunuchs of their race, remained alive to watch for danger and to map out even the deepest of your planet's uranium deposits. The remainder dissolved into gametes, giving their lives to the process of natural selection. The larvae or *elvers* of the Great Eels receive all the non-nuclear nutrients they need from the sea and one another, and produce energy by nuclear fission. (With a little magic, induced gamma emission *definitely* will work, even at the smallest scale). Their task for the coming centuries is to ingest every particle of digestible isotope on the planet. But their lives are constant struggle, an eternal facing off of contender against contender. The losers feed the winners until one day the great cycle continues once more. When they tap into their stored resources and blast aloft, the nuclear fallout will utterly sterilize the planet of all other life. Until that time, your people are free to do as they wish. The Eels remain in the sea - they nearly *are* the sea - and will not bother them. Unless *provoked*, that is. When dealing with outside forces, for Elvers fight and flight are all the same: they activate their immature space drive and fly away on what ranges from a geyser of contaminated water to a pillar of flaming fallout. Because tampering with the Sea of Nightmares can destroy everything within hundreds of meters and spread fallout for hundreds of miles, humans are wary of it. There are few buildings nearby, those tightly regulated. The sea is crossed only by a guild of Navigators, people chosen as toddlers because they naturally play well with animals. Their entry examination is to play on the hole of the asp and put their hand on the cockatrice's den. A skilled Navigator can not merely launch a boat without being destroyed, or avoid being overturned and slain on the Sea. Navigators can understand and empathize deeply with the vast horde of Great Eel larvae all around them, and by subtle hints and motions, place his ship in a path to be moved forward toward the destination. There are tales of ships that made a passage at a hundred knots ... but far more of ships that never returned. [Answer] **Determining longitude and latitude to properly navigate.** Longitude is the vertical lines on a map. Latitude are the horizontal lines. By calculating each line you find your location at the where they cross. They were able to calculate latitude via the angle of the sun at noon. As the sun in different parts of globe has a maximum angle it. Thus if you were at the equator the sun would be directly overhead. There's a chart of the angles and by taking the angle can find the latitude lines you are between. Longitude required keeping time. Greenwich, England was used as the starting point. There's the Greenwich Meridian which represents 0 longitude. Then you set you clock "chronometer" to Greenwich time. Now when the clock hits noon you know the sun's angle at Greenwich. Thus, measuring the sun's angle at your location allows you find the longitude line you are on. The Chronometer was difficult to develop because due to the rough conditions of the boat (movement and water) clocks were not very accurate. Finally in the mid 1700s they developed a reliable chronometer. Before this navigation was extremely dangerous. In fact due to a disaster the English government offered a reward for the person who invented a reliable longitude navigational aid. <https://en.wikipedia.org/wiki/John_Harrison> The guild could have access to a chronometer before anyone else allowing them to navigate accurately from trade port to trade port while others flounder or get loss. [Answer] ## Some thoughts on how to make 'acid' or poison water work Just like real earth has fresh water and salt water, your world has 'poison water' and 'safe water'. People on land don't have to worry too much about it so long as they stay clear of the beaches. Rivers, streams, creeks generally run safe water into the ocean instead of the other way around The poison elements in the ocean do not persist in the air very well. Nitrogen (N2) molecules will neutralize it. But if there is a strong wind from the ocean in the direction of land, it will be carried over on 'larger' (i.e. more than 6 micrometers) water droplets, and so people within a few km of the coast will be in danger. They will need to hunker down in similar ways we hunker down during a tornado, hence there are a lot of wind direction + wind speed meters near coasts, but no communities except operation plants. However, the poison gets neutralized fairly fast when in the air, and so anything more than 15 to 20 km landward people would be safe without need for protection That said, direct exposure in the ocean can be highly dangerous, especially over prlonged times (more than an hour). This chemical compound reacts very fast with nitrogen (and gets neutralized as a result), and it is corrosive to carbon-based materials such as wood and plastic. The byproduct of this poison chemical with nitrogen results in another compound that contains nitrogen atoms in the molecules. However, medium temperatures (e.g. 15 Celsius or more) + sunlight will restore the nitrogen molecules into the atmosphere while the atoms from the poison compound will end up in another form that is not poisonous. Hence, although this ultimately reduces the amount of N2 in the atmosphere, the quantity is relatively stable As a result of this is there are large corporations that specialize in transporting people to and across the ocean. You can also conceptualize other factors, such as politics and federal regulations requiring safety standards for any individuals to cross the ocean, i.e. anyone wishing to cross the ocean must demonstrate to the authorities that they have met certain safety criteria, by which they get a license to travel the ocean, and for which there is a fee (of course). This license must be renewed quite often, and because of corruption the price is fairly high, which prevents the average middle class person from doing so without considerable thought or necessity But certainly, if you wish to take this approach, see if you can pass your ideas by chemists and environmentalists to see if they have thoughts about it. Good luck and have fun with the novel. I'd love to see it when its done *Arts, crafts and sciences uplift the world of being and are conducive to its exaltation ~Baha'u'llah* [Answer] Sailors use natural ocean currents and wind patterns to power their travels. In your world of relatively small inter-connected seas, each "sea" has its own currents but those currents are not oriented in a particularly useful way. Perhaps they're circular (like some of the Mediterranean currents), or they dump your ships into open ocean instead of sending them towards other islands. The return path of a sea current might occur at depth instead of on the surface, so trips could become one-way. Combine this with doldrums that make sails almost useless and you have a situation where sailing is extremely difficult. But not to worry, your Guild of Open-Ocean Navigators are here to help! Hire a local GOON to handle all of your transportation needs. Their mechanically-motorized vessels can propel themselves, without wind and against the strongest ocean currents. No more risk of being stranded until starvation or swept into enemy territory. GOONs can take you directly from point A to point B, efficiently and safely. Accept no substitutes or imitations! Only licensed GOONs have access to the fuel that powers these marvelous machines. [Answer] # Syrup Whatever caused sea levels to rise also slightly raised the viscosity of the seawater, so that more work (whether provided by wind, humans rowing, or a motor turning a propeller) is required to travel the same distance. From an economic perspective, distances between islands increased more than just what the geographic distances would suggest. Changing the viscosity of water would probably have disastrous effects on most things living in it, but perhaps living things can generate a magic field that help them move around enough to cope with it anyway — or conversely the increased viscosity is a magic effect that shuts down around living things (in proportion to the size of the organism, so that the plankton won't just disable the effect). The viscosity of water inside living cells must not be changed. Possibly this sort of thing would lead to a shift in hull designs, towards catamarans and maybe even hydrofoils, but I'm not qualified to comment upon that. [Answer] Some suggestions that I haven't really seen other people bring up... **Large, territorial megafauna** Humans are kind of lucky in that most of the extant marine megafauna aren't huge, and of those that are the majority are non-aggressive filter feeders. Of the large predators that do inhabit the oceans and pose a threat to ships, orcas are weird in that they seem to deliberately avoid antagonizing humans, whereas great white sharks can sink small canoes but cannot harm larger ships. Sperm whales are about the only large ocean animals that are known to attack ships. They don't deliberately do so, but they have been known to sink ships several times their size if wounded by whalers or if they believe the ships to be intruding on their territory during the mating season. An ocean filled with larger predatory marine life that can either view a ship as prey or is highly territorial and has some mechanism that can deal damage to a ship (like the sperm whale's spermaceti-filled battering ram melon) would make sailing much more hazardous because now there is ocean life that *can* stop a voyage in its tracks. If ocean life is aggressive enough it may even slow usage of smaller boats like canoes, if moderately large predators are attacking and sinking small craft every time they get in the ocean. As a result, even if larger ships would be save humanity might never take the necessary intermediate steps to get there. Some species may choose to travel to certain locations to breed or raise young at certain points of the year, much like whales and great white sharks do today and megalodon is thought to have done so in the ancient past. If sufficiently territorial, this would make some islands virtually impossible to travel to for some periods of the year, lest the ships be sunk by angry males believing the ships to be challenging them or females protecting their young. This would force these islands to be highly self-sufficient or starve given they would be frequently cut off. **Extreme tides** Extreme tides, which would have to be caused by some kind of shift in Earth's rotation or Earth's relationship with the moon, could potentially make sea travel extremely hazardous. What this would do is cause large areas of the coastline to be underwater at high tide, but exposed at low tide. This would result in boats very easily becoming stranded at low tide if they anchored too close to the island, or potentially wash rowboats out to sea if people are not very, very careful where they anchor them and drag them far above the high tide line. Another consequence is it would make navigating nautical hazards very unpredictable and unreliable. An outlet that may be perfectly navigable at high tide could be filled with dangerous reefs that would pierce a hull at lower tides. What areas could and could not safely hold a boat would be extremely variable and depend on detailed knowledge of local topography. **Rarity of Fresh Water** Abundance of fresh water typically makes or breaks human habitation of islands. Of the few islands that were not successfully colonized by pre-industrial/age of sail humanity, most of them, such as Aldabra or the Galapagos Islands, lacked any permanent sources of fresh water, meaning they relied on imports of water from elsewhere to be habitable and could not be permanently settled without being supplied water externally. In a world where most of the landmasses are flooded, it stands to reason that there would be a lot of areas that lack fresh water due to the small size of most landmasses. This would mean that ships would have to bring all their water with them or risk death by thirst, making travel in these areas extremely expensive. Most islands without fresh water do have large tortoises that could be used as food, but this is mostly *because* they lack fresh water and therefore humans. Tortoises are known from most large oceanic islands but the ones that had fresh water on them were all wiped out shortly after human arrival (e.g., Madagascar, the Mascarenes, the Bahamas, Bermuda, the Antilles, the Canary Islands, etc.) **Extreme doldrums** Other users have already mentioned this, but I would add in a world with few major landmasses, there would be no continents to disrupt the flow of ocean currents and as a result crossing the equator would be very difficult. The doldrums would stretch virtually unimpeded around the globe and there would be very few ways around them. Few currents would travel through this zone because there would be no trans-equatorial continents, and people would be unable to hug the coastline or travel on foot across the continents to avoid them. **It may be harder to monopolize sea travel than you think** It's amazing to think how far humans are able to get with so little technology. Humans were able to disperse from Indonesia to Australia/New Guinea over water 50,000 years ago, with otherwise Stone Age technology. Furthermore, [the Polynesians were able to disperse to nearly every island in the South Pacific](https://en.wikipedia.org/wiki/Polynesian_navigation) based on a somewhat limited tech base. Polynesian sailing was very refined and the Polynesians had a complex knowledge of shipbuilding (using designs like outrigger canoes) and navigation, but the Polynesians made their actual boats without the use of metallurgy or heavy industry (which if anything only makes the feat more impressive). What this goes to show is that with enough time and motivation even Stone Age peoples would likely learn to be able to navigate the ocean, especially if the world was a series of islands and ocean travel was critical for survival. If people *didn't* learn to sail it would make them incredibly vulnerable to being wiped out if a volcano erupted, the environment was depleted through hunting or deforestation, or if the environment became too heavily degraded for farming or fishing the local waters. Even if the seas were hard to navigate people would try anyway. ]
[Question] [ Many creatures - humans among them - have [binocular vision](https://en.wikipedia.org/wiki/Binocular_vision), where two eyes side by side allow good depth perception. There are quite a few other advantages over one eye, including a larger field of view, as well as redundancy (an injury leading to blindness in one eye won't cripple the creature's sight entirely). I want to develop an Earth-like world where a group of humanoid creatures evolve with a sort of double binocular vision, with eyes in both the front and backs of their heads. Besides this, they would have relatively human-like cranial structure - only one nose, one mouth, one set of ears, and a fairly normal brain. The eyes in the back are perhaps slightly less developed than the front ones, but still quite functional. I'm assuming that this sort of adaptation occurs in many other creatures in this world that would otherwise have normal binocular vision. An extra set of eyes requires a more complicated system of nerves and muscles, and it seems likely that this evolved quite slowly over time. Therefore, I'd bet that more than one species has evolved with this sort of property. My question, then, is this: Under what sort of relatively Earth-like conditions would humanoids develop eyes in the backs of their heads? If you think there's no possibility for this to happen, then an answer supporting that would be, in my opinion, valid (and helpful!). [Answer] If it did evolve it would probably form as a development of the [parietal eye](https://en.wikipedia.org/wiki/Parietal_eye). This is a third light sensing organ that exists in some species of fish, reptiles, and amphibians. This organ is missing from all extant birds and mammals. For such an organ to evolve into a second pair of eyes there would need to be a very strong selective pressure that would encourage it's growth. Since in many some species the lens of the parietal organ becomes opaque as the animal matures there seems to be an active pressure encouraging the lack of use of this organ. Having a second fully developed set of eyes would require a lot of additional infrastructure. Humans would need another visual cortex to process the information they were receiving from this extra set of eyes. There would also need to be a capability to focus on two separate images at once and make sense of these disparate images. A much less developed system could provide a good enough solution to predators approaching from behind. [Answer] ### You need to constantly threaten those humanoids from the back - for example big silent owls and manual tasks that require a lot of time The eyes need to provide an advantage for these humanoids, so there needs to be something they excel at because of their eyes at the back. The first thing that comes to mind are very silent predators. If your humanoids are gathering something, for example herbs, and this process takes quite a long time predators could attack them. Normally we have our ears to detect stuff like that, so the next thing would be to make sure that whatever is attacking is silent. [Owls](https://en.wikipedia.org/wiki/Owl) are exceptionally quiet: > > feathers adapted for silent flight > > > Imagine your humanoids needing to farm something that is rooted quite deep in the ground. And it needs to provide a lot of nutrition, like [Bonegrass seeds](https://worldbuilding.stackexchange.com/questions/38354/how-often-must-carnivorous-grassland-eat), so it's incredibly valuable to get that stuff. Now while your humanoids are concentrating on un-rooting those yummy seeds a bigger owl attacks them. These are adapted owls that normally attack in groups or are so large that they can kill one of your humanoids. The humanoids won't hear them coming - but they can see them. And if their eyes are adapted well enough they might see them soon enough to be able to run away and survive the attack. That might mean that these eyes are better at detecting something in dim light or darkness - maybe they have far more [rod cells](https://en.wikipedia.org/wiki/Rod_cell), which work better in dim light, than we and far less [cone cells](https://en.wikipedia.org/wiki/Cone_cell), which are used for color vision, to make place for the rods. So the back-eyes are colorblind, but can detect something coming even at night when owls are more active. If they are following the humanoids the eyes again show how they are better than anything else - something attacking from behind can be evaded, even if you can't hear it. This might also have other impacts/implications/advantages on/for your humanoids. To quote a comment from [Bellerophon](https://worldbuilding.stackexchange.com/questions/101784/under-what-conditions-would-humanoids-evolve-eyes-in-the-backs-of-their-heads/101785?noredirect=1#comment305132_101785): > > These humanoids would possibly also be less social than humans. If you are a social creature then the solution would be to have a lookout while you collect the yummy seeds. These humanoids seem to be adapted to be able to work alone so are probably solitary or live in very small groups. > > > You can go searching for these seeds far easier alone if you already have someone to watch your back with you - your back-eyes. Without those you would need another human being. Collecting seeds faster is a good way to outplay other humanoids that need to send at least two huamnoids where your species only needs to send one. [Answer] How accurate do you want to be? Let's look at the evolution of creatures, and how that applies to eyes. All creatures of the subphylum vertebrata, have two eyes. That's a very basic template that hasn't varied across over 500 million years of evolution. It isn't until you look higher up in taxonomy, to the basic kingdom of animals, that you start finding creatures with more or less than two eyes, as in a spider's eight eyes, or no eyes at all, as in an earthworm. Anything other than two eyes are very far removed from humans. What has happened in vertebrates is evolution in the capability and location of the two eyes to better suit the creature's purpose. Some herbivores, such as rabbits, have the eyes located more on the side of the skull than the front. This severely limits binocular vision, but gives near 360 degree vision coverage, better for spotting predators. Raptors have evolved a magnified spot in the center of their eyes... good wide vision for a general search for prey, the magnified spot to fully identify a potential target. Some creatures have nearly non functional eyes, like whales, who do most of their 'seeing' with sound reflections. A more likely evolution for rear vision in a human like species would be a head that could rotate 180 degrees quickly, such as horses, cows, and deer have. That could happen without variations to the basic vertebrate template, just lengthen the neck. Better than the rabbit's side placement, this would keep the acuity and depth perception of binocular vision, just add the capability to look in more directions quickly. In the case of night predatory attackers, like a very large owl, that evolution might also include better night vision to spot the approach (more rods than cones in the retina), possibly an enhanced sense of smell to detect the odor of nearby predators, or as humans tend to be intelligent, the knowledge of where the large owls tend to hunt, and avoiding those locations and times, or possibly developing disguises, or even countermeasures like the thrown spear. [Answer] Don't start from mammals or chordates, because that implies late panspermia. Instead, build a world (this is Worldbuilding, after all!) Have all major animals on this world have four eyes. Quadrilateral symmetry would make this more likely, but "quadrilateral symmetry" is a slippery fish. You could have the symmetry last only for a time as they develop in the womb, as ours does: even mammals are arguably, at some very low level, quadrilaterally symmetric - two limbs above, and two below. So if their symmetry lasted just a little longer, such animals could evolve into bipeds with manipulative arms, or animals designed to move quickly in one direction (our quadrupeds), and so on, but that their design is *more* quadrilaterally symmetric could inform your design of them, beyond the fact that four eyes was the typical pattern. Prey animals would naturally tend to have the four eyes at four corners around their head, rather than paired. This would grant them stereo vision for 360 degrees. They wouldn't have to make the tradeoff that earth prey make, trading binocular sight for angular resolution. The rear eyes might migrate out on stalks/horns, the better to see around the body as they eat. Predator animals would tend to have the rear eyes migrate forwards, up over the head or around the sides, granting them better peripheral vision for hunting, and perhaps being co-opted for other uses that the main eyes did not fill. Extended out on stalks to help with cooling, the extra eyes could be sensitive into the infra-red range. Scavengers, opportunist feeders, would tend to vary between the two, and a state where the eyes were arranged in two pairs, front and back, could make a lot of sense, since it would still give about 360 vision, but binocular only "ahead" and "behind", which requires a whole lot less processing, allowing other parts of the brain to develop more, instead. For bipeds, the ahead/behind distinction might not make much sense: they might have one direction in which they can move more rapidly, but if they can look in both directions, it's likely that their arms would be arranged such that they could manipulate items on either face of their body with roughly equal facility. Perhaps one side would be more capable at fine work, and one more capable of hard physical work and fast movement. Perhaps one set of eyes would naturally lean towards long-sightedness, and one to short-sightedness. Perhaps, like left/right handedness, they could be dorsal/ventral-favored, favoring one or the face (which could lead to various social complexities, biases, genders, etc). Perhaps they would have a subtly different concept of left/right than we do ("on the left as you walk down the road" is unambiguous; "your left arm" is ambiguous to something facing in both directions). [Answer] **Why the Parietal Eye?** I'm going to echo @sphennings and go with the parietal eye. I have chosen to follow this path because, as far as I can tell, the parietal eye is the **only** occurrence of extra eyes in creatures with spines. Unless the new set of eyes forms from a completely novel mutation (possible but by my estimation so unlikely as to be impossible) or genetic engineering, it seems like the best option. Furthermore, I'm going to assume that, if humans have the new set of eyes, so do a vast array of other mammals. Mammals evolved from relatively small reptiles (living relatives of which do have the parietal eye), which would have certainly had a good reason to keep (not select away) the rearward facing eye. If humans were the only living mammals with the rearward eye, them you would have to explain why humans kept the eye while all other mammals selected it away. **Why Keep the Eye?** So why would humans, who are a relatively dominant species within our ecosystem, have such a pressing evolutionary need to sense what is behind us? I'll agree with @Secespitus and go with the predator theory. We would have needed to have dominant, constant depredation from species that attacked us from behind and above. **Predators** Now, what preys on your humans (and their great ape ancestors, and their simian ancestors all the way down the line) can vary to fit your story. Again, as far as I can tell, these predators would have to be ambush predators coming from above. If the area of your world where humans evolved is covered in forest, cliffs, and ravines, then you have a little more flexibility. If it is out on the plains, then you have a little less. With structures to leap from, you could have any sort of predator that fills the jaguar, drop bear ecological niche. This could be a jaguar or a tree-dwelling lizard or a species we don't have back here on earth. With or without structures to leap from, you could have any sort of predator that fills the silent flight, giant Owl niche. This could be owls, this could be flying reptiles, or this could even be some sort of angel-looking humanoid, up to you. [Answer] Bottom line is that you simply wouldn't get a group of humanoids evolving a second set of eyes, any more than they'd evolve a second set of legs. The basic vertebrate body plan is too deeply imbedded in the HOX genes for that. If you want humanoids with 360 degree vision, you have two alternatives. First, if this is a completely alien world, you have everything in that world's vertebrate-analogue lineage have four eyes. (Perhaps becoming vestigal in some branches.) If you are going from an Earth-descended creature, you're basically limited to repositioning the eyes. They could for instance become like the eyes of horses, located to the sides of the head, and with an oblong pupil, giving nearly 360 degree vision (but binocular vision only in a narrow cone): <https://en.wikipedia.org/wiki/Equine_vision> This wouldn't be all that difficult to arrange, evolutionarily. Just have your ancestral humanoids spend a lot of time evolving on the open plains, with a lot of predators eager to eat them. They'd likely acquire other horselike (or antelope & other plains creatures - I'm just more familiar with horses) attributes such as being good runners. [Answer] There is one way this could happen, in a manner that's similar to what has probably already happened in vertebrate evolution. As you may know, for some reason, nerves in higher vertebrates are flipped left/right. What I mean is that, the left hemisphere of the brain controls the right side of the body, and vice-versa. [![enter image description here](https://i.stack.imgur.com/WIIEK.png)](https://i.stack.imgur.com/WIIEK.png) How did this crazy situation evolve? First, note that for non-vertebrate animals such as insects are wired "correctly": the left hemisphere of their brain controls the left half, and likewise for the right. What one scientist proposed is that, during vertebrate evolution, there was a creature that evolved to have its head rotated 90 degrees, so it was looking sideways. Then, there was selective pressure to have it looking "forward" again. Instead of evolving to undo the twist, it kept twisting, to go a full 180 degrees! What was this animal? Something like the flounder, whose eyes, during development, migrate so that two of them are on one side of its head. It lives its life on the ocean floor, lying and swimming on its side: [![enter image description here](https://i.stack.imgur.com/40J8d.gif)](https://i.stack.imgur.com/40J8d.gif) So, suppose your humans evolved to have eyes on both sides of their heads, like many prey animals. All it needs to do is evolve to rotate its head 90 degrees, and boom! eyes in the front and back. As Stephen Pinker explains in *The Language Instinct*: > > No biologist has explained why the left brain controls right space and > vice versa. It took a psycholinguist, Marcel Kinsbourne, to come up > with the only speculation that is even remotely plausible. All > bilaterally symmetrical invertebrates (worms, insects, and so on) have > the more straightforward arrangement in which the left side of the > central nervous system controls the left side of the body and the > right side controls the right side. Most likely, the invertebrate that > was the ancestor of the chordates (animals with a stiffening rod > around their spinal cords, including fish, amphibians, birds, > reptiles, and mammals) had this arrangement as well. But all the > chordates have "contralateral" control: right brain controls left body > and left brain controls right body. What could have led to the > rewiring? Here is Kinsbourne's idea. Imagine that you are a creature > with the left-brain-leftbody arrangement. Now turn your head around to > look behind you, a full 180 degrees back, like an owl. (Stop at 180 > degrees; don't go around and around like the girl in The Exorcist.) > Now imagine that your head is stuck in that position. Your nerve > cables have been given a half-twist, so the left brain would control > your right body and vice versa. > > > Now, Kinsbourne is not suggesting that > some primordial rubbernecker literally got its head stuck, but that > changes in the genetic instructions for building the creature resulted > in the half-twist during embryonic development—a torsion that one can > actually see happening during the development of snails and some > flies. This may sound like a perverse way to build an organism, but > evolution does it all the time, because it never works from a fresh > drawing board but has to tinker with what is already around. For > example, our sadistically designed S-shaped spines are the product of > bending and straightening the arched backbones of our quadrupedal > forebears. The Picassoesque face of the flounder was the product of > warping the head of a kind of fish that had opted to cling sideways to > the ocean floor, bringing around the eye that had been staring > uselessly into the sand. Since Kinsbourne's hypothetical creature left > no fossils and has been extinct for over half a billion years, no one > knows why it would have undergone the rotation. (Perhaps one of its > ancestors had changed its posture, like the flounder, and subsequently > righted itself. Evolution, which has no foresight, may have put its > head back into alignment with its body by giving the head another > quarter-twist in the same direction, rather than by the more sensible > route of undoing the original quarter-twist.) But it does not really > matter; Kinsbourne is only proposing that such a rotation must have > taken place; he is not claiming he can reconstruct why it happened. > (In the case of the snail, where the rotation is accompanied by a > bending, like one of the arms of a pretzel, scientists are more > knowledgeable. As my old biology textbook explains, "While the head > and foot remain stationary, the visceral mass is rotated through an > angle of 180°, so that the anus . . . is carried upward and finally > comes to lie [above] the head. . . . The advantages of this > arrangement are clear enough in an animal that lives in a shell with > only one opening.") > > > In support of the theory, Kinsbourne notes that invertebrates have > their main neural cables laid along their bellies and their hearts in > their backs, whereas chordates have their neural cables laid along > their backs and their hearts in their chests. This is exactly what one > would expect from a 180-degree head-to-body turn in the transition > from one group to the other, and Kinsbourne could not find any reports > of an animal that has only one or two out of the three reversals that > his theory says must have happened together. Major changes in body > architecture affect the entire design of the animal and can be very > difficult to undo. We are the descendants of that twisted creature, > and half a billion years later, a stroke in the left hemisphere leaves > the right arm tingly. > > > [Answer] Humanoids will not be able to develop two sets of eyes from a humanoid form based on evolution theory. The development of the eye has long been used by creationists in trying to disprove evolution theory on the basis that very slight alteration to the eye would make it not function anymore and thus have no evolutionary basis. It was later proven with a computer model that fish eye could be developed from light sensitive patches to a fully developed eye with each evolutionary step in between beneficial to the creature. I cannot see how you would be able to create such a same track from a normal human to a four eyed human. The whole needed restructuring of the brain would simply not allow it. Maybe more interestingly why did eyes develop in the front of our head. This traces back to our fish ancestors (I think). They actually don't really have a back of their head since that is where there body is. From there we just evolved with eyes at the front and side. If you would like eyes in the back of your head I would start with the evolution from those fish with eyes on eyestalks, or maybe from snails. From that tract you could devise an evolutionary path with a third or fourth eye in the back of their head, since via the stalks you can connect them to the same part of the brain. The stalk part can later be developed away as being to dangerous as they are sticking out. It would entail rewriting the complete evolution track for all animals. Keeping and developing the multiple eyestalks is most likely with encircling predators and predators that like to attack from the back. Later getting eyestalks to retract into the head while keeping the eyes would most probably involve predators specifically targeting protruding eyes as a means to incapacitate an animal. [Answer] Eye location is driven by the direction of the most efficient locomotion and tracking food. Your creature would need to be equally as fast and as agile in two directions and would also need to be equal in food tracking. This forward/reverse motion would also need to be more efficient than just turning around. A good starter point might be some sort of creature that evolved similar to a pilot fish which follows another animal. Your creature would have evolved in some way to only be able to follow a trail left by another animal in a straight line without breaking off to the side except in extreme conditions (like the line was broken by a fissure or crossed another line close enough to let the creature "switch tracks". For the Food source requirement, the tracks would need to spontaneously generate food in random locations either in front of or behind your creature that lasted a very short time, making the sight in both directions a food selective and therefore reproductive trait. [Answer] As others have said, it is highly unlikely that your world's version of primates would develop three or four eyes if most of your world's version of mammals, or vertebrates as a whole, had only two eyes. Four-eyed humanoid beings could only be plausible or likely to occur if most or all animals in their world had four eyes. The evolution of four eyes should happen hundreds of millions of years in the past and four eyes be a trait of all animals on the planet or else a very big group of them - maybe half the different classes and phyla of animals. So the four-eyed humanoids on your world should be surrounded by thousands of other species of four-eyed animals and every critter should should have eyes in the back of his head. [Answer] A couple of other answers have mentioned spiders and spines, but I don't think anyone has taken this to the logical conclusion yet: Vertebrates on your world can't independently turn their heads. Either their necks don't twist like that (lots of reasons--either the joints are a completely different type of joint, or there is a restriction in the soft tissue--like us compared to owls/praying mantises) or they don't even have necks (like frogs and spiders). This happened early on (from an evolutionary standpoint) when eyes were simple light-sensing patches, and a random mutation lead to more eyes spread apart to provide a broader field of vision, instead of any of the other solutions common on Earth (rotating neck, or eyes super wide apart). Eventually the common pattern was to have eyes in pairs for binocular vision, with some eyes facing forward and some facing backward. Once the multiple eye solution was going, it was a lot easier for all 4+ eyes to become more complicated simultaneously, and brains naturally kept pace. Only a few odd ball vertebrate animals have fewer than 4 light sensing organs and anything that can rotate it's head is viewed as super flexible and weird. Your aliens would probably marvel at how fragile and complicated our necks are, one bad fall and you can be completely paralyzed...how did our ancestors ever survive... [Answer] My answer would be that it would happen by chance. Under similar conditions as Earth, its quite possible that a different kind of sentient species evolved as the dominant species. Its quite possible that on this planet a long time ago a common ancestor of many current species mutated the trait to have extra light sensitive organs, which would eventually land on the back of the head of a successor which evolved a "head", and these sensory organs became eyes either prior to or after this division. In order for these extra eyes to continue to exist it is important that they do not hinder reproductive success of individuals across the millennia it would take for a humanoid species to evolve. A natural selective pressure would greatly assist in the further development of such eyes in some species. Such as a predator prey relationship between two species with a common ancestor. They both would have the extra set of eyes, but its the prey that would benefit more if it had better eyes to avoid death. But that does not stop the predator to further develop its rear view eyes for other reasons. Its also quite possible that social barriers exist in species that would increase reproductive success in individuals with certain types of eyes. Not necessarily for the better. Either way, the selective trait must exist before the selective pressure, or then it would just become a race against time for a random mutation to produce a trait that would allow the individuals to survive the pressure prior to extinction. The more complex the organism the less likely this becomes. So chance it is. The die is being continuously cast since long time ago, and you've got extra eyes. [Answer] As many others have said, I'm sure, there would need to be selective pressure for the use of them. In my opinion, I don't believe it's possible. Having a second pair of eyes similar to our already binocular front would actually be harmful rather than helpful. The head must be enlarged to allow a second network of tissue, and the spinal cord would have to be altered or moved. This also creates the issue of having more physical vulnerabilities. Finally, the cranium would also have to be enlarged because the brain would have to have more connections to process two separate, unconnected fields simultaneously. I feel like the actually selection process has solved this issue. Owls and cats have so many vertebrae they can twist their necks to see a full rotation, with only one field to process. The best I'd say is go the route similar to the Andalites of Animorphs and have them have stalk eyes as well. Or have a different sense that is only concentrated behind the humanoid, such as infrared sensing, some sort of echolocation etc. ]
[Question] [ For the story I'm planning out, the setting is on one of the worlds of a technologically advanced extraterrestrial race well-known for their economic infrastructure, which includes incredibly efficient logistics networks that are capable of transporting matter across continents and between neighboring planets at low cost. The availability of resources for those who are truly in need is practically a guarantee; charity is considered to be a respectable, but not at all mandatory, action, and many of the largest companies -- alongside the tens of thousands of smaller businesses and wealthy individuals -- are generally happy to contribute. Charities determine who gets what, and for how long. Generally, if the recipients are able to work, but don't have jobs, they are given supplies so long as they are actively seeking out employment. Various safeguards are in place to assure that nobody slips through the cracks, while simultaneously ensuring the system isn't cheated. The problem that I am facing is the issue of poverty in such conditions: I had imagined the main character's backstory as one of poverty, coming from a very poor family, without considering the exact details as to how that's possible in their society. With faster-than-light communications and transportation, coupled with the availability of both work and affordable goods, and the presence of such vast amounts of resources for the genuinely impoverished ("genuinely" as determined by the agents who determine eligible recipients), **is there any reasonable way to remain in poverty?** I've thought long and hard on this, and the only justifiable answers I've been able to come up with are: * if a frontier world or a distant colony is outside the usual logistics routes; * if some physical disruption (i.e., debris fields, singularities, raiders, etc.) were to cut off routes; * if individuals are too stubborn to receive aid, but aren't capable of holding down a sufficient job, either. [Answer] As someone once said, "The poor are always with us". That's because poverty is relative, not absolute. The people who are considered poor in Western society today have, in many ways, wealth exceeding the wildest fantasies of medieval aristocrats: indoor plumbing, modern medicine, TV and cell phones, the work of writers & musicians available at the wave of a hand. So the bottom fraction of a population will always be 'the poor'. Even in a Communistic society: it's just that there the poor are the 99% who aren't Party functionaries. [Answer] What about a non-participating community? There could be something similar to the Amish - a separate minority subculture that rejects large portions of the primary culture. They could either object to the technology, or even charity itself on theological or ideological grounds. Then your character can originate from that community, basically living in poverty until he's exposed to the primary culture and decides to switch. [Answer] How good are the safeguards? All it takes is one corrupt bureaucrat who decides to make the protagonist's life miserable. Even if there is normally enough oversight to prevent abuse, that might not apply to a frontier world which nobody pays much attention to. To make the local environment even worse, add in a bit of crime. The money is only adequate if it isn't constantly being stolen/extorted by those who have given up on finding a legitimate income. [Answer] Even with plentiful aid delivered perfectly efficiently, there are still reasons why people might be 'poor' (relative to the average in your world). Perhaps they spend unwisely and end up over their heads in debt. Or they gamble everything away. They sell the aid they do receive to buy drugs or other illicit items/services. They might be mentally ill and not able to take care of themselves... but refuse to willingly be placed in homes. Or they might just be flat out lazy and irresponsible, refusing to get jobs or unable to keep them. [Answer] I doubt this fits your scenario, but all charity/welfare systems that make efforts to "prevent cheating" have a fundamental weakness that you may be able to exploit. That is the concept that some people are not worthy of charity or support, are less deserving than others. This is confirmed by the "actively seeking out employment" mention. This means that members of minorities or people with other issues **will** fall through the cracks. This is an issue even in state ran welfare systems where the bureauacracy often fails at managing people that don't fit the expected patterns. On a system based on voluntary charity the charity organizations will have a natural tendency to focus on people they concern most deserving, and people who don't fit the definition that particualar organization has of "deserving" will never even make the list. If all the charitable organizations available share the same definition of deserving, the affected people will get support from nowhere. This obviously works better if the location is some backwater where the availability of charity sources is more limited. People might also be unfamiliar with the system for some reason and have reduced ability to seek aid. This is common for people with mental health issues, addictions, immigrants, minorities... Pretty much all systems that are in danger of falling thru the cracks, really. From the utopian flavor of your system, I'd assume there is some system for fixing such issues. So the issue would be short lived. Something that first affects the parents of the character and gets fixed after he has grown up. Having it take that long also supports some more remote location and that the particular minority/issue is specific to that location and largely unknown elsewhere. I can't really give specific suggestions to fit your setting, but generally this would be an ethnic or religious minority that for some reason is considered undesirable by their neighbours. Visibly different, different customs... [Answer] * ***Option #1***: **The person is mentally ill** Use a realistic approach that is true even in the modern First World countries. A large chunk of truly poor (homeless) is that way due to a **mental illness**. *I can expand into more detail if you're interested in exploring that approach*. --- * ***Option #2***: **Micro-society with the strong/powerful taking from the weak**. Again, pretty much modeled on what we see in reality: in many poor countries, the amount of aggregate aid from rich countries dwarfs the needs of the poor. BUT, that aid doesn't go to the poor who need it - it goes to either **corrupt local people in power**, OR to whoever is strong enough to take the resources by force from those weaker - which could very well be your uncle or someone else in the family, so donors don't know about it. --- * ***Option #3***: **Deliberate living off-the grid.** Someone is paranoid about being on-the-grid. **Remember, if you aren't paying for the product - you ARE the product!** Or you run a criminalish underground enterprise and don't want connection to modern infrastructure that can track you. --- * ***Option #4***: **Poverty by choice.** People rejected material wealth and underwent privation by choice often - for religious or philosophical reasons. Ascetics, early-Christianity Syrian monks who sat on poles, assorted vows of poverty. You can't charity-help someone who prefers to remain impoverished. --- * ***Option #5***: **You are abhorrent to everyone.** You (your actions or opinions) are so **abhorrent that NOBODY wants to give you charity**. That's the libertarianish beauty of charity vs. welfare - you aren't forced to support someone who wants you dead/hates you/etc... OK, out of all my approaches, this one is ironically the one that is 100% definitely "fictional" and doesn't possibly exist in our modern real Earth world. Women fall in love with, marry and send money to serial killers in jail. People follow Hitler. People wear Che Guevara tshirts. People vote for "(GWBush|Obama:pick one)". People defend Saddam, Stalin, Al-Assad and Mao. People give money to ISIS. There's literally NOBODY who is so abhorrent that 100% of human race would shun and not support them. [Answer] The protagonist's parents could have been self-sufficiency fundamentalists who were not only too stubborn to accept aid but also philosophically opposed to all the philanthropy around them. In their evangelism of the virtues of personal integrity, they may have offended their potential employers, leaving them at the mercy of the charities which they loath. Alternatively, the protagonist's parents might be charitable extremists who insist on giving away all of their assets and revenues. Despite holding respectable and highly compensated jobs, neither parent keeps enough of the income to provide more than a spartan existence for the children. As usual, the extreme points on any spectrum seem to resemble each other more than either of them resemble the median centerpoint. [Answer] You summed up the problem very nicely: "Generally, if the recipients are able to work, but don't have jobs, they are given supplies so long as they are actively seeking out employment." If a family has a culture which spurns the available jobs, just how much aid do they get? They might, for instance, hold that they are intrinsically superior (bloodlines, ethnicity, a famous ancestor, etc.) and reject any job which pays less than they believe they deserve. Or they might reject the attitudes which would allow them to keep the jobs they do get - things like showing up for work every day, or working for a boss who does not "treat them right". [Answer] **A few alternative ideas!** Maybe your protagonist comes from a 'military' family and was raised on the front lines of a conflict where resources were scarce. Or perhaps he grew up in space, serving the needs of people working on transports and freighters. He would never have enjoyed the luxuries of those who lived a 'normal' life. Thus, his family would likely have no real estate holdings or a planet to really call home. Another thought: If your main character's father was once a well-known criminal or otherwise disgraced the family name, would that not affect him adversely growing up? If so, he would likely have been (unfairly) denied opportunities and rewards that others received freely. [Answer] I'm not sure whether you meant "reasonable way" or "plausible way". One way that occurs to me immediately is that some people might choose to remain in poverty. It seems inconceivable that anyone would actively make that choice. And yet... in the middle ages, there were several monastic traditions that required, on entry, a vow of poverty. People took that vow, and many took it seriously. A cynic might argue that everyone who took such a vow did it out of some form of disguised self interest. I choose to look at it differently. I think that some people want to get things out of life that poverty enables more than comfort. For some tradition other than Christian, all you have to do is look at the life pattern of Gautama Siddhartha (the Buddha). He gave up a life of wealth and power to pursue a different goal. [Answer] I saw several answers that posit that maybe your main character either refused charity or did something terrible enough that everyone refused to give him charity. What if this society is not post-discrimination - and the main character falls into a class of person, through no fault of his own, that the charitable don't feel so charitable toward? This doesn't necessarily have to be one of today's hot-button topics of inequality, though it could be (likely turned on its head), especially in a space-faring fiction: race could be redefined as species, or else as discrimination based on world of origin. Perhaps your society believes they have transcended gender and virtually everyone is either hermaphroditic or neuter - and they all view your male character as backwater or strange. Perhaps your character's sexual orientation differs, or his religion (maybe just *having* a religion is stigmatizing - many people today seem to think of religion and science as incompatible, maybe that viewpoint spread)? My personal recommendation is that your character was originally born into money - a high class family who lost everything. The reason would need to be worked into your story, of course: maybe they supported a failed coup (or supported a supplanted ruler), perhaps they invested in a failure/rebel/con artist too heavily, any number of random, natural, or intentional events could bankrupt a family. And then those in charge of doling out charity don't feel they deserve any more help, given how poorly they managed the wealth they had or their history of bad decisions (even if it was just the one, not the character's fault at all). [Answer] I agree with an earlier post about wealth/poverty being relative. I assume that you are thinking of the kind of poverty where you can't maintain one or several of the basics - food/clean water/decent healthcare/accomodation. And you would really want people in the underclass to die from the lack of any of these things to up the ante. So you really need to make something essential scarce, and then it doesn't matter how good the transportation/welfare system is, the scarcity won't make it to the lower classes. Perhaps some essential vaccination that is expensive to make (or purchase from a private company). Or poorly designed and dangerous accomodations - these won't be improved by good transportation. But remember, once basic needs are met, there are other higher level needs. The underclass may not have the same opportunities for education, or travel. Perhaps they have to work hard labour from an extremely young age. [Answer] *There is probably a lot of unemployment in your universe*. Quote: > > technologically advanced extraterrestrial race well-known for their economic infrastructure, which includes incredibly efficient logistics networks that are capable of transporting matter across continents and between neighboring planets at low cost > > > Sounds like there are few people involved. The jobless who are provided charity as long as they actively seek employment *might easily make up over 50% of the population*, and many will be forced to "actively seek employment" *for their entire lives* without ever finding any. People will be depressed and cynical, and will drop out of that system. Better to be poor but free than somewhat more comfortable but forced to do pointless job searches forever. [Answer] A few ideas: Perhaps the parents have a job, and thus are not eligible, but it is low paying, and they lose the money that they do have quickly, for some reason. -Maybe gambling, or rent. -Paying the local gangs to leave them alone. -It's big family, so the money is stretched too thin. -Or maybe they just donate everything they get! For some reason, people could refuse to let them spend their money. They are secretly rich, but they don't want to spend money because they don't want to draw attention to themselves(they are hiding from something from the past). [Answer] Poverty is relative. As another answer explains, what is considered poverty in some parts of the world would be considered wealthy in other parts of the world. For example, in the USA, the poverty line is roughly [$11000 for an individual](http://en.wikipedia.org/wiki/Poverty_in_the_United_States#Recent_poverty_rate_and_guidelines). Whereas in other parts of the world such an income per year would be considered quite wealthy. Secondly, if you are dependant on government aid to live day to day, you will struggle. The amount of money or other resources made available is inherently less than what a person would earn when working - other wise there is no incentive to work. As such the protagonist would feel poor as they are not able to get new toys or other things that kids at school might have. This also brings up the social stigma relating to being on some kind of government hand out or benefit. Rough neighbourhoods, or bullying of those who have to rely on government aid. [Answer] **All the current real world ways. Nothing really changes.** Poverty means not having the income to sustain a certain standard of living, either by not having any income, or that income being too low. Charities giving food and shelter do not attack the root of the problem, they only alleviate it. Your poor won't starve or be homeless (well, there's always the ones who refuse the help), but they'll stay poor until they get that income. [Answer] To stay poor your protagonist could : 1. receive but refuse aid -pride or shame -especially if their family became poor as a result of bad judgement on their part or treason, etc 2. become a convict or castaway - maybe wronged by law, maybe misjudged or not and really guilty of something that made them live "outside society" - or their family that had such premises and the protagonist gets to live in such conditions, plus the social stigma that can cause him/her to avoid others either for shame/pride related reasons or for fear of reprisals. 3. become somehow marooned on a "desert island" - say they managed to land a damaged ship on a planetoid surrounded by a deadly asteroid belt and/or communications are blocked for some reason and they can't contact others (think modern sci-fi Robinson Crusoe) 4. have other priorities in life- not necessarily a monk and poverty vows but certain high risk jobs that also demand terrible working hours and although the pay is more than adequate,our poor guy or gal does not simply have the time to spend and enjoy his/her fortune and lives a miserable, overworked and joyless, basically poor life-despite the actual monetary resources that are there but never taken advantage of. Could be temporary.Practical poverty but not actual poverty, still all the hallmarks are there- extreme tiredness, lack of proper meals at regular intervals, high stress,low quality and quantity sleep usually not far from if not near or in the office, always at the ready- think emergency doctors, think front line commanders active in wars or maybe more exotic professions like navigators in dangerous space regions while traversing vast perilous expanses etc. 5. if the setting allows for that-be fallen /disgraced nobility, or bankrupt businessman or investor- used to have lots, made bad decisions or unfair conditions were imposed on them, now they are basically poor and slowly recovering but there are issues with receiving charity. For one, they have been rich for so long nobody would list them as top priority, and they are proud enough to not let the situation be widely known.Prior status somehow hurts rather than protects in this case 6. have too much good will - they will give away even more than they owned if they could, because they support maybe not society in general but some specific research or ongoing good cause they totally believe in so they pour their all into that. 7. be or become as a result of some change- any kind of cultural refugee. A dissident if you will.Maybe a reformist who does not agree with the ways of society and seeks alternate survival methods 8. really wild here : exiled king,fallen former master of a territory/domain.The ruler of the previous society exiled by a victorious revolution 9. Tarzan the jungle boy/gal - he/she is totally adorable and would/will be supported by society but alas, their ship crashed on a relatively uninhabited jungle planet (now I'm going all B- and C rated movie tropes here) or variations thereof 10. Not Tarzan the jungle boy but somehow they slipped through time and lived in a distant -think almost bronze-age-like past and now returned from there . Accidental or deliberate - until they fixed the thingmabob that can get them back where they belong, all their inventory will consist in a bunch'a skins, a stick with a pointy stone tip and/or several small makeshift tools. Cavemen from the future past...When they finally get back all they are rich in is lice and stories. [Answer] A few other answers touched on some of this but i didn’t see it put together quite the way i saw it, soo With the phrase “Coming from a background of poverty”, as i translated it, i would assume it to primarily be a parent/family situation in his past, not a really personal to him situation. Kids don’t have a say in who/what their family is or has. And any charity determining who gets what, is dependent on where they get their information from, and where it goes to (specifically to a family not necessarily one person within a group or to a parent not a child). Also, there are limitations and stipulations like has to seek work if able, and potentially other lawful/moral restrictions. So one possibility is, someone(s) in the family were… misdiagnosed as able to work when they actually weren’t. They then can’t claim from charities, and can’t hold a job - and trying might make things worse. They might be able to get a second opinion, but… if it was a borderline case, if it didn’t fit a social narrative (as historically visible vs invisible disabilities narratives ran), if they believed they “should” be able to overcome the issue (re mental health misinformation today), self blame or victim blaming, if they or others trusted a doctors diagnosis over an individuals, they might not get one or if softly asked it might be influenced by what was already in the file not a truly independent second opinion. In that case, they don’t get the charity. (Specific note: something genuinely mistaken would not trigger any precautions aimed at malicious behavior, and it can be hard to untangle when biology is messy and people can be convinced that the inability is a question of *fault*. Sigh) Now, there’s implications for the family as a whole. They have to survive on less than what they “should”. Dividing what they do have best they can to cover the extra. Charitable society, and the family should believe those virtues and of course would support their own especially if they can see a genuine struggle. One more thing, though, is others judgements… they know charity is available and so-n-so Didn’t qualify. Isn’t trying. Opinions drop. But wait there’s more - they have less per person and higher costs, maybe extra expenses to cover whatever that misdiagnoses left out, needs, and so maybe they have to step back from ordinary charity… I’m thinking community things like bake sales or volunteering or whatever. Less funds or time or energy. However, this also serves to distance them from the community. So now they’re being judged for not -*giving* as much as they should. Not maintaining community standards or social ties. Are they really part of the social and support networks, if they don’t contribute?? Opinions drop. And this becomes the whole family issue instead of just the misdiagnosee, because they are supporting each other. So-n-so might be lazy, but… rest of the family is, supporting them? Enabling them? Letting the kids survive on less just because so-n-so didn’t want to put effort in?? Opinions drop. So charities, don’t want to give. Community doesn’t want to support, and individuals judge heavily that the rest of the family is allowing such behaviors. Uhoh looks like a hard time for that family. Additional complications - if it’s an invisible/difficult to diagnose health issue, more than one person in the family might have had similar situations/issues, either presently or historically, which affect the family’s reputation and access to charity, and/or spread the resources they do have thinner to cover extra people. And, another factor might be that, given the whole family might be considered actively complicit in supporting so-n-sos “choices”, they might choose not to offer aid to others in the family, or even a child of the family the way they might for shortages from a more “deserving” reason. And independent of that, a poor reputation might encourage other poor assumptions for the family, like accusations (real or false) of criminal action and so on. Further reducing their presumed eligibility for charities. And last thing? individuals might start losing faith in each other, the charity system, the medical system, the local community… because something is wrong but what n how to fix it, isn’t clear. So there would be a poverty, from lack of resources per person but also some of the lack of faith in system or poor community cohesion we sometimes see in underserved communities today. We might see overreliance on system/beliefs by those “escaping” such a family/community. In short that’s a lot of room for human messiness for plot points or character development. [Answer] Just how long does the poverty need to last? I can see two routes to poverty in childhood: 1. Abusive parents. We see that now, they actually have enough money but the drink/smoke/drug/gamble it away rather than providing for their children. If it's severe enough CPS usually gets involved but on the milder end it might not be apparent. 2. The parents are criminals on the run. Life in the shadows, they can't avail themselves of the help available because they would be caught and sent to jail. [Answer] There is a difference between **charity** (given at the discretion of the donor) and **welfare** (an entitlement of the recipient by law). **Welfare** ultimately means that the government redistributes wealth from the rich to the poor through tax collection according to laws and regulations. You *don't* mess with the tax men unless you have really good lawyers ... If there are more poor people and fewer rich people, initially the state goes into deficit to pay out the welfare as prescribed by law. This deficit will have to be made good somehow, through taxes or budget cuts (possibly welfare cuts) or currency devaluation, but that takes time. **Charity** means individuals decide to pay or give. Perhaps this month they're busy. Or they have less to give. Or it isn't Christmas season and they don't feel like giving. Or there was a disaster on another continent and too many donate for that. The bottom line, you can't rely on charity. You can only hope for it. [Answer] Just because a society is "highly charitable" doesn't mean they think everyone deserves it. There may be strings attached, there may be open racism or religious discrimination, etc. Even on a purely economic basis, your description provides one easy opening: > > Generally, if the recipients are able to work, but don't have jobs, they are given supplies so long as they are actively seeking out employment. > > > If the definition of "actively seeking out employment" is too burdensome, or the definition of "able to work" is incorrect, then someone might remain in poverty. Someone might obtain (be required to, or they obviously weren't really seeking it) a job whose salary puts them below the poverty line, but not considered to "truly need" charity because they have a job. All of these problems exist today for welfare, and there's no obvious reason that they wouldn't likewise exist for private charity even in a "highly charitable" society. [Answer] While this is an extraterrestrial race if you start with the [fundamental needs of humans](http://en.wikipedia.org/wiki/Fundamental_human_needs): * subsistence - food, shelter, clothing * protection - social security, health systems * affection - friendships, family * understanding - school, literature * participation - responsibilities, duties, work, rights * leisure - games, parties * creation - invent, build, design, compose * identity - places one belongs to * freedom - autonomy, passion, self-esteem You can imagine a world where a charitable society only fulfils some of these needs but withholds others thereby making one poor: * Giving you food and shelter (subsistence) but not friendship (affection). Perhaps going so far as to make people leave existing friends and family and live in a [poorhouse](http://en.wikipedia.org/wiki/Poorhouse). * Giving you clothing that is really a uniform that identifies you as poor. Causing other members of the community to treat you as a pariah. * Not giving you protection (perhaps on this planet you have to subscribe to a police service) so that you constantly fear for your life. * Not giving you access to computers/Internet or limiting it in some way. This could deprive you of many things leisure, social networking sites, etc. You could even have a planet where everything is very drab, utilitarian looking and there is no visible form of recreation. However, people spend much of their time in "the better world" which is some sort of virtual reality or holodeck where you can meet other people, engage in almost any leisure activity with them, create and view works of art, etc. ]
[Question] [ The Martian Sol is 24 hours and 37 minutes long, so daytime at a fixed point on the planet's surface will drift in and out of sync with a fixed point on Earth's surface, and keeping the tradition of a 7-day week would have similar implications. Roughly every 39 days on Mars, 40 days will have passed on Earth. Suppose the Martian colonists want to set up their weekly calendar so that their weekends occur *roughly* at the same time as they do on Earth. Maybe they want to not be bothered on weekends. Maybe there's some other social or religious benefit. The exact reason why is not important here. Also assume this is sometime after basic terraforming so that people live above ground. They certainly *could* go by Earth time and avoid the problem entirely, but this quickly and regularly gets them out of sync with the natural biological instinct to go by whatever the sun says. Living your daily life in darkness for 19.5 days on, 19.5 days off doesn't make a lot of sense. You could do something like leap days to handle this, but those 37 extra minutes do not divide evenly. It's *almost* a 6 week cycle, so doing something like skipping Wednesday every 5th week will cause Mars weeks to drift ahead slowly. Therefore you would need to create an additional rule of some regular interval of *not skipping Wednesday* on a fifth week. But then that creates another syncing issue. Layers have to be added until enough precision is achieved, just as we do for leap years. Are there other alternatives that are mathematically consistent without being too difficult to remember? It would be pretty awful to go to work on a Saturday because you forgot that Friday got skipped this week. Or you could miss work because you thought Friday got skipped, but it wasn't. If skip days are the only reasonable way of handling this, is there a strategy that could be used to help people remember without it feeling like which day is skipped is arbitrary and unpredictable? [Answer] The solution for this is intercalendary days, like you suggested. This is needed any time something doesn't divide neatly. Our day doesn't divide neatly into our year so the rule is: * February 29th exists when the year is divisible by 4 * Unless the year is divisible by 100 * Unless the year is also divisible by 400. So 2000 and 1600 are leap years, 1900 wasn't. 2100 also wont be. Your Wednesday rule will need to be something similar. Skip every 6th Wednesday unless it's the xth Wednesday but not in month y sort of rule. It could be made as memorable as our full leap year rule. Most people who hear the full rule disagree and google it because they only learnt the rule of 4. I go to work when my smartphone alarm goes off, and would on Mars too. Note that doing this would anger some religions that want to keep their weekend in sync with the 7 day cycle. Orthodox adherents would have to shift the date of the sabbath by one day every missing Wednesday. Like they would if we adopted the [World Calendar](https://en.wikipedia.org/wiki/World_Calendar) --- Addendum: I did start trying to calculate the exact rule to make this line up, but it's going to be a pain. The martian week is 620494 seconds, the Earth week is 604800 seconds. These form a cycle every 26.8 billion seconds (43,200 martian weeks). A "Martian weekend syncing calendar" is going to need to be this complex. I wasn't able to calculate it fully due to time constraints, but it will be at least: * Base clock loses 15694 seconds per week. * Skip every 6th Wednesday. Now we lose only 5522 seconds every 6 weeks. * Skip every 97th Tuesday. Now we lose only 649 seconds every 100 weeks. * Skip every 13641st Thursday. Now we lose only 28ms every 366 weeks. [Answer] If it works with your general scenario, they could just have a regular week, but switch the Earth timezone they sync with West every ~2 days. They would drop a day when they cross the date border, but would always have someone on Earth that shares their weekday and roughly time of day. Of course the would not work if ground control is based in one or few neighboring timezones. But if UN Space or a multinational is doing the groundwork, they could have four+ control stations around the globe that periodically take over main responsibility and are during that time roughly synced with Mars. The advantage of this scheme is that setting up meetings would work better with your current ground control - you not only have the same weekday (mostly), but also roughly the same time of day. How would it work in practice? In the following, I will list how the conversion would change. I will always give Raw Mars Time first - this is the time that we don't want to use since it will drift away from Earth. Then I will give timezone and time that Mars syncs with at that time. Times will be in "24-hour format", Raw Mars Time days end at 24:37. * Monday, 00:00 = Monday, 00:00 UTC * Tuesday, 00:00 = Tuesday, 23:37 Azores time (UTC-1) * Wednesday, 00:00 = Wednesday, 00:14 Azores time * Thursday, 00:00 = Wednesday, 23:51 Mid-Atlantic time (UTC-2) * Friday, 00:00 = Friday, 00:28 Mid-Atlantic time * Saturday, 00:00 = Saturday, 00:05 Brazilian majority time (UTC-3) * Sunday, 00:00 = Saturday, 23:41 Paraguay time (UTC-4) * Monday, 00:00 = Monday, 00:18 Paraguay time * Tuesday, 00:00 = Monday, 23:55 ET (UTC-5) * Wednesday, 00:00 = Tuesday, 23:32 CT (UTC-6) * Thursday, 00:00 = Thursday, 00:09 CT (UTC-6) ... and so on. You basically move one timezone West when you come too much out of sync. When you cross the date border, you have to skip a day. [Answer] Since the lack of a magnetic field would pretty much force any large scale habitation to be done underground and any time spent outside being expensive and needing shielding it wouldn't be at all difficult to use Earth time. They could use Earth time underground and translate to Martian on the rare occasions they go out which would mostly just be specialists doing tasks. Specialists on Earth do the same thing. Pilots go through timezones, sailors keep track of tides and other cycles etc,. [Answer] Frame Challenge: When asked why you responded with this comment. > > I think it could reduce surprises for the people who need to interact with Earthlings. Sending an email on a Tuesday on Mars could reasonably take a day for a response, but if you don't realize that's their Saturday at the time, you end up having to wait 2-3 days for a response. Obviously, it's never going to be exactly the same, but if you can rely on an assumption of "Earthlings are within 30 hours of my time and day of week", that would be pretty convenient. > > > So essentially it sounds like a fundamentally practical problem. You need your Martians to be able to interact with Earthlings in a way that doesn't cause frustration. I think your Martians would solve this by running two Calendars. The Martian Calendar would fit the local conditions, seasons and social needs. Possibly dropping the seven day week, 12 month year altogether for something more sensible. All their technical gear can also display an Earth clock showing them the time, date and day of whatever part of earth they work most closely with. So they know it's earther weekend just by picking up a phone. Starting a colony on Mars means everyone taking the same weekend is not going to work. Your environment is trying to kill you, someone is working to stop it every day. Even decades later when life is routine the concept of a shared weekend doesn't catch on again. And having two clocks on a phone is pretty simple. You can probably get a widget showing you ['Martian time and date'](https://play.google.com/store/apps/details?id=uk.co.digitaltrust.marstime) from your app store right now. The biggest problem with this set up is Earthlings don't know if their contact is on [xyr](https://genderneutralpronoun.wordpress.com/tag/xe/) weekend when they send xem a message. But given the 'always on duty' outlook of Martian pioneers that has persisted chances are someone will pick the message up quickly in any case. [Answer] **Spin up Mars!** (so it comes to sync with Earth) As a part of the teraforming process they need to haul large masses of water and other volatile substances. Think about Asimov's martians that bring a kilometers-sized piece of Saturn's rings. To bring them down to the surface, instead of landing them softly, an acretion-like process may be used. This will transfer angular momentum to Mars. Few (thousand) quakes later and after a great deal of fireworks they will have denser atmosphere, brand new hydosphere and a planet that rotates properly. [Answer] "Layers have to be added until enough precision is achieved." What's wrong with that? It's not like every schoolchild has to do the math on their own. Think leap years and leap seconds on Earth. Only one institution with a handful of super-smart, super-knowledgeable time nerds has to do the math. It publishes the results with a very high lead time. The information trickles downs through other institutions, onto regular people who don't need to know anything beyond "month lengths vary and I should check a calendar". So, most Martians only need to know "week lengths vary and I should check a calendar". Not much would be lost. We have fixed week lengths on Earth, but for many people it's not rare to not know the day of the week before checking their phones. [Answer] ## Frame Challenge: Syncing weekends would not happen The reason everyone here on Earth likes to sync up their weekends is so that normal people can predict when service businesses will be open or closed. These are things like restaurants, doctor's offices, tech support hotlines, etc. But between Earth and Mars, there can be no exchange of services, because they require real time communication. Mars is 4-24 light minutes away from Earth depending on orbital positions; so, ANY time you communicate with Mars, you have to wait for a response. This means that even those service jobs that can be outsourced between time zones on Earth (like tech support) stop being able to be outsourced between planets. As a result, 99% of the time critical things that apply to international exchange would not apply in an interplanetary environment. The only things you need to coordinate between worlds in your case is the occasional inter-planetary shipments of goods, but these are huge multi-million dollar transactions handled by a small handful of specialists who would have no problem looking up Earth time in their already specialized tracking software, and those shipments already take the better part of a year to get from point A to point B; so, having to wait an extra 1-2 days for a shipment to be confirmed because you emailed someone on their weekend does not really make much of a difference in the grand scheme of things. We modern people think everything has to be in real time, but pre-industrial civilizations functioned just fine waiting days, weeks, or even months for communications to happen; so, the evidence is already there that good planning and a bit of flexibility is all you really need here. As for weekends being staggered, many different Ancient civilizations observed different days off. Some only took off Fridays, some only Saturdays, some only Sundays, and they all had their own sets of local holidays meaning a traveler could always be surprised by closed shops because they arrived on some local festival day. So, your 2 planetary calendar system would in most ways already be more predictable than many historical systems. When you consider that Mars has very little reason to need to sync up with Earth time, you should then ask yourself, how big that minor need is compared to their need to observe their own calendar. Tracking their own days, weeks, and years is something every Martian will need to be able to do. When do they need to go to work, or plant crops, or make a phone call to other Martians. For this, the simplest solution is going to be the best one; so, since observing a consistent local time will be thousands of times more useful to most Martians than worrying about what time it is Earth, it is unlikely that they will make the effort to do anything like this at all. [Answer] Only one rule: Every month that is single digits starts a weekday skipped. (The rule does not apply to october, november, december as those are double-digit months, but any mechanism to pick 9 months per year works.) This will keep martian weekends pretty well aligned with earth weekends for a long time. Example: August 31 is a Monday -> September 1 is a Wednesday. [Answer] ## Weekly on/off stacking alternating cycle The problem with Ash's answer is that it's not as simple as it can be. Think about it, you have to deal with a full day one way or another every time you skip for any reason. So you might as well pick nice, round numbers as much as possible. Might give yourself a 10% buffer or so to be more flexible. Here's my explanation: * Every 5 weeks, skip Monday or Friday * Every 40 weeks, don't do this * Every 480 weeks (approximately 5 Martian years), do this anyways * Every 27,840 weeks (approximately 250 Martian years), don't Derivation: **Every 5 weeks skip** So you start out ahead 15,694 seconds every week on Mars, so you need to take a day out somewhere at some point. There are 88,643 seconds on each Mars day that we will be skipping. That's roughly a factor of 15,694 / 88,643 = 1 / 5.6, so we need to choose skipping the 5th week or skipping the 6th week. I choose the more frequent one so that we swing the pendulum back the other way, which allows the next correction to restore a day rather than taking a further day off (sorry, no 3 day work weeks). Five week drift minus one Martian day the other way (15,694 \* 5) - 88,643 = -10,173 seconds ahead every 5 week cycle on Mars (10,173 seconds behind). **Every 40 weeks don't skip** Now we have a factor of 1/8.7. We again want to round down so we skip less often, so the next correction is every 8 5-week cycles we interrupt the skipping. 8 cycle drift plus one Martian day the other way (-10,173 \* 8) + 88643 = 7,259 seconds ahead every 40 week cycle on Mars (-7,259 seconds behind). **Every 480 weeks skip** Now the factor is 12.2. Round down to 12 40-week cycles, and apply the correction same as the first time. 12 cycle drift minus one Martian day the other way (7,259 \* 12) - 88,643 = -1,535 seconds ahead every 480 weeks. **Every 27,840 weeks don't skip** Now the factor is 1/57.7. Round to 1/58 (we're stopping here) and apply the correction same as the second time. 58 cycle drift plus one Martian day the other way (-1,535 \* 58) + 88,643 = 387 seconds ahead every 27,840 weeks. That seems close enough (factor of 229 which would be one day in ~57,000 years) ## Other cycles Looking at this, I'm sure that the actual Martians will be able to figure out a much more clever arrangement after years of doing business with Earth. For example, if you do a 6 week skip, your factor is then 1/16 (5,521 seconds), which would mean adding another skipped day every 6 \* 16 = 96 weeks which is very close to a Martian year. If you do it yearly, you could choose whether to not skip if the yearly lands on the same week as the 6-week cycle, or choose to do it the week before/after. That buys you an optional 6 year cycle that you could choose based on which brings you closer. After that it could all be yearly based. If you do the year, we have to do the calculations by day. 5,521 seconds per 6 weeks is 131.45 seconds per day. There are 668.5991 Martian days in a Martian year, which means that we would be losing 87,888.94 seconds per year with the 6 week cycle. With the yearly skip, we'd bring that down to gaining 754.06 seconds per year. Every 6 years would be 4,524.34 seconds, so we'd have to double up the days off when they fell during the same week. Every 19.59 years we'd be another day off the other way, so why not every 20 years skip the yearly leap. We're at a cycle greater than 1,000 years after this point. [Answer] Running the Maths, I think this is how it works: A Martian Day is 88,642 seconds. An Earth Day is 86,400 seconds. Over the course of 365.25 Days, Mars will have an excess of 818,890.5 seconds to lose, which equates to 9.24 Mars Days. So they can skip 1 day a month for 3 months out of every 4, and then they can mirror Leap Years on Earth for the other 0.24 of a day, except rather than adding a day they'll skip a day. [Answer] The solution could perhaps be to work at a lower level and modify the smaller time increments, rather than trying to fit a martion day into an earth one, If martian timekeeping used a slightly extended length of time for a second (or minute if preferred) then hours and days would stay in sync with their earth counterparts. Devices on mars would need to be configurable for the different time setup, but this should not be an insurmountable issue. Workers on mars would benefit from slightly extended lunch breaks at the cost of slightly longer working days. I leave it to others to do the maths for the optimum time adjustment... ]
[Question] [ Historically, units of measurement are often based on sizes of body parts. Probably the most obvious example would be a "foot" literally being based on the length of someone's (or everyone's, or anyone's) actual foot. Other examples include inch (length of a thumb, from tip to first joint), cubit (elbow to tip of middle finger), and span (from tip of thumb to tip of little finger, when spread as far as possible). For most historical human populations that used these types of systems, this worked well enough for their day to day lives, despite the different sizes of body parts from one individual to the next. When that size variation *was* a problem, they could standardize, somewhat, by using the body part of a ruler/monarch/lord/etc. instead of just some random individual. Enter the worldbuilding conundrum of populations that include both human and non-human races, some of which have distinctly differently sized body parts, or might even be missing a body part that another race has. The exact races present are not necessarily relevant to the question, but for illustrative purposes, I'll provide a couple quick examples. A lizard-human-hybrid type race would have a tail, that a human would not. A race of merfolk that are more fishlike than the standard trope might have webbing between their fingers or might not have fingers at all with fins or flippers in their place. Giants or dwarves/halfling-esque races might be mostly human shaped, but wildly out of proportion to humans in actual size. In a world-building setting where at least 2, if not more, such races commonly and constantly interact, making body part lengths inappropriate as common units of measurement, **what is the most likely basis for such a society to use as units of measurement instead?** **EDIT** First, apparently I wasn't clear enough that I was looking for answers that did not include the use of body parts of the races, at all. As in: body parts are off limits as an answer. The question was meant to ask for alternatives to body parts, not variations on the use of body parts or how body part usage could be standardized. Next, a note about the monarch and other variations of standardization, I understand that a monarch creating a standard is often how things were done, but this question was meant to be about what that monarch himself might have based his official standard on, if not his own body parts or someone else's. Sure, his official bar of metal could still be used as the defined standard, but what did he base the length of his official standard bar of metal on? Answers that basically state "they'd all just agree or learn to convert": sure, but what would they use as a basis *before* they learned to agree on one or convert, if not body parts? Assume the location is actual Earth, with the only difference being the additional races present, and assume ancient and/or medieval, as anything more specific shouldn't really affect the answers, since it's about what people from *any* of those time periods might use. In other words, what things on Earth, other than the race's body parts, would make a good basis for widespread common units of measure? A commenter mentioned Barley Corns, and that is actually the only reference I could find in my research that was actually used historically, and this is exactly the kind of thing I was hoping for in answers. Other items in comments and answers that fit the spirit of the question include horsewidths, trout lengths, birch leave length, ant lengths, bananas, elephant tails, and narwhal tusk. Though horsewidths and barley corns are the only ones that I both know enough about and can confirm are sufficiently consistently sized and widespread. [Answer] We have used non-human body parts for measurement before. Roman roads were just broad enough to allow for two horses to go side by side on them. If anything, though, the usage of body parts from one species might make the other feel misrepresented. This may lead to tensions which will hasten the adoption of some sort of universal, scientific measure. The revolution from which this arises may be called in your world *le metric tensor*. [Answer] Measurement units have followed a fairly standard pattern. Originally things are compared to something that both parties recognise. It could be a specific thing (the Washington monument) or a general thing (a [banana](https://knowyourmeme.com/memes/banana-for-scale)). No one is really measuring anything accurately, so this is good enough. Next people start to measure things against their own standard. This is usually merchants, who need to measure to set a price. They need something repeatable, so they use a particular stick for length. It might be similar to the length of a banana, because that's what people are used to, but other people may have chosen a different basis for their stick, and even if they didn't, their sticks will be different. Next all the different measuring sticks are standardised by a local authority (king, merchant's guild, etc) so they can collect taxes. They either take an average or go with whatever the richest merchant was using. The same process can occur when two countries standardise - but normally a small country adopts the units of a larger neighbour. Finally scientists define a more precise version of the standard. [Answer] You give your own answer! > > When that size variation was a problem, they could standardize, > somewhat, by using the body part of a ruler/monarch/lord/etc. instead > of just some random individual. > > > There is some historic individual who has made a big impression on all of these involved races. Measurements reference body parts and famous exploits of this legendary explorer / philosopher / inventor / conqueror / lover. This would be fun for a fiction because with each reference readers would wonder what all this individual got up to during his action-packed time. Maybe he even shows up late in the story. [Answer] Well, for one, it's unlikely that having multiple races would affect using body parts for measurement; humans come in varying shapes and sizes after all, and that's why we moved to more objective forms of measurement as our technology allowed for it. At most, you'd wind up with a situation where they say things like "that's an orc-foot long" or "that weighs a dwarf-pound." However, I imagine just waving away your question isn't a very satisfying answer, so let's try and figure out a solution through world-building. Creating a metric system requires a significant amount of technology and understanding of mathematics and the sciences, and even modern SI units are poorly defined for certain dimensions (the speed of light is, by definition, 299792458 m/s, but the meter is defined as the distance traveled by light in 1/299,792,458th of a second, so you can see the problem, the kilogram was defined by a 200 year old reference standard until only a few years ago, and its replacement, a silicon sphere, isn't without controversy). However, since it's a fantasy world, you can invoke a bit of magic, handwaving, or both. You could have a tree that inexplicably always grows a branch of a roughly identical length, or have a race of people that always reach the same height upon reaching adulthood. You could have a magical spell that's been bestowed upon the world by God of Measures, that allows for proper measuring. Another possibility is, depending on how savy your people are, or how well they can measure time, would be for them to measure the difference between two shadows of a stick at different times on a specific day. For example, your measure of length might be something called a "springbow" which is defined as the distance between a shadow cast by a stick at the 1st bell and 4th bell on the day of Spring Equinox. Assuming that the time of bells is well-defined, presumably through a well-regulated clock, one would expect this distance to be identical on the Spring Equinox every year. As such, you could even have a "Festival Of Measures" where the townsfolk gather to observe the measuring of the springbow, and reference measuring sticks are provided to all in attendance for free. Even this has some problems though, as for the springbow to be identical, it has to be measured at exactly the same time *in exactly the same place* and must neglect the effects of procession. Worse, you have to know exactly where to measure on your shadows, and measure from that point every time. Procession is easy to hand wave away; you could say it's small or nonexistent for your world. The place is also easy to define. You could use a marker in some important city in the kingdom, perhaps the Royal Courtyard or so. The last question, where to measure on the shadow, is much trickier, and becomes a question of "who measures the measurer?" However, this is a problem we, with all of our technology, deal with today as well. Even though we can 'define' what we mean mathematically by a kilometer or a volt, measuring it is not as easy, and we're constantly revising our system of measurement as our technology allows for higher precision measuring of it. So in your fantasy world case, perhaps you could use last-year's official springbow reference stick as a kind of "ritual of renewal." This will limit, but not eliminate the error in measurement, but would still leave you with measurements that far exceeded the precision of the ancients, plus it provides for a good plot device that can lead to interesting storylines (what if someone steals the previous year's springbow, or it gets lost, for example). [Answer] Measurements were originally derived from things aside from the human body. The acre was originally the amount of land that could be plowed by a yoke of oxen in one day, and eventually became defined as a strip of land a furlong in length and a chain wide, with the furlong the length of a furrow said oxen could plow in one go before having to rest. What's needed, initially, is something that is convenient for all the races in question, that is pretty standardized, and they agree on. For instance, suppose there's a widespread species of tree that, when mature, tends to have a thickness of around (what we'd call) a foot. So if you have one of those trees, some chopping yields you measuring sticks. The single greatest issue is convenience. The units that stick around are the ones that can be used every day without needing excessive precision. A good example is the foot. Despite Canada officially using metric for decades now, the foot still sticks around because it's a unit of convenient size for everyday use. There's really no natural subdivision of the meter that works. On the other hand, litres are close enough to quarts, and thus to quarters of a gallon, that said switch worked out easily and quickly. Meters easily replaced yards (except in football) because they're both about the same size. But the good old foot, that's going to stick around for a while yet. [Answer] Different races world most likely still use their own body parts among themselves. When interacting with other races they would learn to change between units. If the races have been in contact with each other for a long time, it would be easier to use measurement units taken from elsewhere in their nature, from animals and plants common enough that different races all know them. Trout length, birch leaf length, three ant lengths and so forth. A system similar to a metric system is obviously the best, but that was not the question. [Answer] They could continue to use their own body parts, and simply be aware of conversions and other rules of thumb. If a human and a halfling are negotiating for some number of feet of cloth, they should establish *which culture's* "feet" are being used. (Or, maybe they don't and this is one way unscrupulous vendors try to swindle people in your universe.) In pre-modern Earth it was common for well-established cultures to nonetheless have different units and different definitions of the same unit coexisting. Take the *[pous](https://en.wikipedia.org/wiki/Ancient_Greek_units_of_measurement#Length)*, the Classical Greek "foot", for instance. In Athens it was typically a hair under 300mm, but in Aegina it was about 10% larger. Of course, this sort of untidiness leads to added difficulties in map-making, treaty drafting, trade, and taxation, so governments don't tend to like it very much. Among the accomplishments of most of your serious empire-builders, you'll find that they inevitably establish standard measures to be used throughout their empire. (I'm thinking here particularly of Qin Shi Huang, but there are many other examples.) Probably some of the "body" units in your story will fall out of favor as the cultures that promulgate them do the same, to be replaced by "standard" units based on those of the preeminent cultures. [Answer] The reason people used body parts was its something everyone could reference. Given that's not the case with multiple fantasy races, then they'd likely use some other common reference. Perhaps they'd measure lengths in bananas. Or Elephant tails. How much is that rope? Its 2 coppers per Narwhal tusk. [Answer] If you already have standard measurements for, e.g. time, you could base things off of that. E.g. a candle that is tall enough to burn in one hour is a candle-length. Sure, some one-hour candles might be taller than others, but the same is true for the body-part measurements that would otherwise have been used. If a certain type of candle has been around long enough to become a basic staple of modern life, you could expect its length to be relatively standardized. You could even mark smaller increments of time and length by having ruled candles with marks for every e.g. 5 minutes, and units of length could be tied to the amount of candle that burns in a given amount of time. [Answer] Look at the Holy Roman Empire. Basically every city and principalia had its own units. This shows us two things concerning your question: Firstly that people could life and trade with different units of measurement and second that those units supposedly based on body parts lost their reference after a while. For example the Hessian *Klafter* was 2.5m, Considering that the *Klafter* is supposed to be the reach of a man's arms(similiar to a fathom) and therefore quite exactly the size of one, it seems that Hessians were giants back then. I don't know exactly why you don't want to measure using body parts. But then the question becomes very broad. Basically everything that has a somehow uniform size could be used as a unit of measurement. And when societies grow larger and grow together they will start to standardize their units of measurement. [Answer] Use circles. The angles would be consistent regardless of the size of the circle, especially if you make them concentric to evaluate them. Then use the distance the stars move in a particular time frame. Perform a few calculations and you can come up with latitude and longitude and from defining a unit of measure as the set fraction of the distance between latitude lines you can derive the equivalent of nautical miles. [Answer] Why not use the size of the Earth itself? This is, after all, how real life got both the nautical mile (conceptually one minute of latitude, or 1/21 600 of the circumference) and the meter (1/40 000 000). It can be measured with good-enough accuracy using the knowledge available to Eratosthenes (276-195 BCE). Of course, as technology improves, more accurate surveys can be taken, while the standardization definition of the length unit will likely stay the same for the sake of backwards-compatibility. This is how we arrived at our current situation where Earth's polar circumference is 40 007.863 km (error of 197 ppm from the conceptual 40 000 km) or 21 602.517 nautical miles (error of 117 ppm from the conceptual 21 600). You will of course need to choose a convenient *fraction* of the circumference to use as your main length unit. And this is where having multiple sapient species makes things get complicated. For not only do you have to deal with orders of magnitude (e.g., a mouse would likely prefer a smaller unit than an elephant would), but you can't assume that everyone will be counting in base ten, which IRL comes from the human habit of counting on our ten figures. Some races will have different numbers of fingers, and some won't have fingers at all. So maybe you have one base-6 society and one base-10 society. Maybe they'll compromise on base 8 (their arithmetic mean) or base 30 (their lowest common multiple). In the former case, you might define a “foot” equal to 1/8^9 of the planet's circumference (298 mm), and in the latter case, you might have a unit that's 1/30^6 of the circumference (54.88 mm). [Answer] We're in this exact situation on this planet right now: [![Map of countries not using the imperial system](https://i.stack.imgur.com/4KPqD.png)](https://i.stack.imgur.com/4KPqD.png) Within one part the planet, the one type of aliens use one system, whereas in the other part the other aliens use another system. So the answer to your question is: *Wherever the aliens do not talk to one another, they use their own system,* but if the one alien tries to sell something to the other alien or wants to talk to the other alien in very precise measurement, *they just relabel their products for the other alien's market because* **the customer is king and you want to serve your customer as best as you can!** So *there is no common system, unfortunately...* # :-) [Answer] **The 'Problem' and the Answer** If you're disallowing body parts as the foundation unit, even if they're the body part of a particular individual, then that leaves other physical objects, and repeatable physical phenomena. For example, one culture might use a {unit} defined as the length of the shadow of some famous monument, taken at local noon on the Equinox. This length will be identical to the shadow of a same-height object at any other location of the same Latitude, and once 'reference' {unit}s are created and shipped around, *any* town can create a durable monument which casts the same length shadow at local noon on the equinox, allowing them to create their own {unit} sticks locally. **Disclaimer** But, really, you're working on solving a non-issue in the first place. Even if a 'foot' was determined by the size of your own king's foot, those measures would vary from kingdom to kingdom, and conversion charts would be created by merchants who traveled among them, so they knew how to price their goods for the local market. (Otherwise, selling your textiles in a kingdom with a size 13 foot would be vastly less profitable than selling the same textiles in a kingdom with a size 6 foot.) [Answer] You are chasing a non-issue. Variation among races doesn't matter. By the time the variation of other races matter, your culture isn't using natural measurements anymore. handspans work fine even with a wide variety of races because by the time the difference in hands matter you are not using real handspans anymore. First nothing in nature is consistent enough for precision measurement, They get used early then abandoned, the name sticks around the unt they no longer use the actual thing. examples include body parts, grain seeds or livestock body parts, feet were the most common just becasue the first thing that people are measuring is ground distances and feet are convenient. People are lazy they are not going to carry around things to measure with. seeds get used for volume because there is nothing convenient to measure volume with. Of course for much of human history it did not matter, measurements were basically just tallies and eyeballed measurements. What a culture will pick is entirely situational, based on the local wildlife and population. Handspan, grains, feet, ect. works fine because you are either only trading with locals (debt based trade) in which case they can both see your hand and already have a culturally ingrained idea of what you are talking about, at this point measurements don't have a lot of use and when they do it is things that can be directly compared, from here to that tree, yay high, large vs small. Eyeball measurements are good enough nothing more precise is needed. If you are trading with strangers measurements don't matter, trade is goods for goods that are both present at the same time, in which case unit measurement in pointless. Once you get to long distance trade you are already at the level that standardization begins, because languages are not shared in common. You are using direct comparison (scales, standing two things next to each other, ect.) just due to language barriers. Measurement does not have a lot of use until you start getting widespread writing, which is a long way away, and grows with standardization. by the time you get to a culture that needs unit precision they have standardized, usually based on some kind of stone monument. It may have a name like handspan, but its based on the hand of a single statue or set of standardized statues there is minimal variation. It doesn't matter how big the hand of the guy you are trading with is. [Answer] There are some natural quantities that are fairly constant. If your society has a modern understanding of physics, it could use some of these constants. $g = 9.807\ \rm{m}/\rm{s}^2$: A pendulum 1 meter in length swings at 0.5 Hz[1](https://en.wikipedia.org/wiki/Seconds_pendulum). Given the number of seconds in a day, the monarch could figure out the right pendulum length. And, in one second, a dense object falls about 4.9 m. This is why movies scenes filmed on a tiny set need to be slowed down. $g$ and $P = 1\ \rm{atm}$: A column of water forms a vacuum at about 10 m at 1 atm pressure[2](https://what-if.xkcd.com/143/). 1 atm is also 760 mmHg[3](https://www.google.com/search?q=1+atm+to+mmhg). However, as you noticed, even if your monarch uses these definitions, the average person probably won't, unless your monarch gives out lots of rulers. And even modern rulers are only accurate within maybe 1% and change length with temperature. [Answer] Lots of good answers here, but one point missing is the patterns of trade. Weights and measures start with trade. Initially you are going to have things like a trader using his own arm to estimate one yard. Where humans trade with humans this works fine. It also works fine when dwarves trade with dwarves: the fact that a human yard and a dwarf yard are different is not important. Where life gets interesting is when dwaves and humans meet at the market. Modo Snorisscousin (dwarf) knows that he needs three yards of leather, but the product he needs is being sold by John Thatcher (human). You can write the dialog from there. Most likely Modo and John will compare arms and conclude that three dwarf yards is about two human yards, near enough for trading. All over the market similar conversations are taking place. Eventually the rough conversion factors get to be common knowledge. Except that three dwarf yards is actually a bit more than two human yards, so if you are selling 60 dwarf-yards of rope its going to be more like 36 or 38 human-yards, so don't get short-changed by those crafty dwarves. Exact knowledge like this will be considered an important part of merchant lore, but not widely shared because it lends competitive advantage to those who hold it. [Answer] When it comes to worldbuilding, these differences and variations SHOULD be a part of that world. Erasing them says just as much about the world as letting them be--it says something about who leads in trade, about differences in culture, about government and far, far more than you would think. The takeaway is this: instead of asking how you can have uniform measurement, you should be asking why it would exist at all. **In the real world where humans don't have this variation in size and body parts, we already have and historically have had vast variations in measurements. It's never been uniform. So if your world is similar enough to draw a comparison, it actually makes less sense for there to be one single standard without a compelling, in-world cultural reason for this to be true.** You're worried about inconsistency when in historical fact, units of measurement in early history have always been inconsistent. Units of measure varied from town to town in Medieval times. Standardized measures are something that is determined by a ruler or ruling class or who has power in trade, which much then enforces that. The re-frame is, of course, what others have suggested--that the physical difference between the races means two different standards of measurement. Even today, on a global scale, there are two different major standards. And within industries, there are other standards still, sometimes vestiges leftover from a much, much earlier time (such as the measure of "grains" in gems.) Making the basis something that is more consistent is difficult. Even IF you use an agricultural product (barley's consistency means that it was used as a measure of weight and length in past times) what agricultural product it will be might vary as much as body size and weight from race to race. Grain actually has been used in weight quite a bit. And barley [HAS been used in length](https://en.wikipedia.org/wiki/Barleycorn_(unit)) ]
[Question] [ In a world that's essentially a carbon copy of our own, through mean's no one knows how, people started developing superpowers. With seemingly no rhyme or reason, people got powers of all shapes and sizes, like a woman who can fly to the stars, or a man who can turn into a flaming peacock. Some people used these gifts to do heroic things, while others used them to commit various crimes. All of a sudden, heroes and villains that seemed ripped straight from comic books became a reality. Yet, some people don't want to use their new abilities for either crime or for crimefighting. Some people want to use their gifts to make some cash. Like Tobias, a man who can understand animals, wants to open a pseudo-Veterinarian clinic where people can go and pay him to figure out what's bothering their pets. Or Lucy, the demon girl who wants to open up a tourist service with her sentient bus that can go into the Underworld. Or Jeffery, a giant half-spider, half-man who, with the help of his children, can use his silk to make intricately woven clothing, and the methods which he does so could revolutionize the fashion industry. For every hero or villain out there, there's someone else with a power who wants to use their new gifts to start their own business or try and make some cash. Assuming that every law in regards to businesses and business practices remained the same as people started developing powers, what would have to change for people to be able to legally use their powers in their own, or other people's, companies? [Answer] In the US at least, nothing. And I can't imagine it would be much different elsewhere. > > Like Tobias, a man who can understand animals, wants to open a > pseudo-Veterinarian clinic where people can go and pay him to figure > out what's bothering their pets. > > > There are licensure issues for veterinary services, just like there are licensure requirements for human medical services. As long as Tobias is licensed, there's no reason he couldn't use his powers to improve his veterinary skill. And if he isn't licensed, there is no reason he can't accept payment to tell people what their pets are thinking. Even if the law doesn't recognize his powers, that's not materially different from accepting payment for, e.g., fortune telling, which is legal. > > Or Lucy, the demon girl who wants to open up a tourist service with her sentient bus that can go into the Underworld. > > > Does she have a drivers license? Do the tourists sign liability releases? At some point, someone might decide to challenge Lucy on whether or not the tourists require passports, and if customs and border control need to be involved, given that the Underworld probably isn't US territory... but there are existing businesses that already deal with that. The supernatural nature of her particular services would not be relevant. > > Or Jeffery, a giant half-spider, half-man who, with the help of his children, can use his silk to make intricately woven clothing, and the methods which he does so could revolutionize the fashion industry. > > > The only tricky bit here is that the product is made from the output of Jeffery's own body, and there are issues with selling human body parts. But you could probably argue that silk is analogous to hair in this regard, and it is legal to sell human hair and use it in consumer products (like extension and wigs)--so there *may* be a lawsuit over this, but it is not foregone that the law would actually have to change to permit it. [Answer] As [logan](https://worldbuilding.stackexchange.com/a/177327/76099) said, there isn't much you have to change to allow people do stuff, mostly because laws are made to prohibit things, not for allowing them. Nobody needs a law to allow them to eat, but society have laws so nobody can keep you from eating (a.k.a.: killing you by hunger). So expanding on this the most changes on laws will be to make sure nobody is using their newfound abilities to screw other people, like: * forbid contracts when brainwashing is suspected * using live humans to fabricate products * make bad weather to disrupt normal logistics * etc. Now, if this world is a carbon copy of ours then you have to keep in mind that laws are also made when somebody is making a lot of money with their work and the state/powers that be ain't receiving their share, so expect stuff like: * travel tax for going to the underworld * special taxation on items moved trough portals instead of normal ways, so as to give them a "fair chance" * the government shutting down your panacea-selling company because it's not approved by the FDA * needing medical licence to fix people, even if what you're doing is rewind time on their lost limbs or making them grow new ones. * etc. [Answer] [Logan covered](https://worldbuilding.stackexchange.com/a/177327/10324) your specific examples, so I'll be more general. Except one detail: Jefferey employs his children. Child employment? Be very careful about that! The most important question here is "what is a person?", the most basic qualification for being a citizen. In our world, it is very rarely a problem to decide what is a person, what is an animal and what is neither. In your world it might be trickier. Demons? Half-spiders? Children of half-spiders? Somebody needs to make some laws about that. In some mixed couples, the human can be accused of zoophilia and/or animal abuse. Your focus is not superheroes, but I need to say one word about them: Vigilantism. Most jurisdictions have very strict laws about what private citizens can do in terms of law enforcement. What one person calls a citizen's arrest, another will call assault. While this is not the focus of your story, it is likely to be in the background somewhere, for example as a reason for a character to choose a peaceful profession instead. [As KiraraVS wrote](https://worldbuilding.stackexchange.com/a/177329/10324) telepathy and related powers will require new laws. One *can* make the case that this is just spying and coercion by other means, but at the very least there will need to be case law deciding how to interpret existing laws in the new context. A whole lot of laws will need to be interpreted in new contexts. Lawyers are going to get richer. Then there is work safety rules. These can be laws, regulations or union rules. Superman can argue that it would be perfectly safe for him to grab a girder on the ground, fly up to the top floor of a building under construction and hold it in place while other workers fasten it into the structure. Don't expect the union to agree. They will argue that a) Rules Must Be Followed and b) Those rules are there to protect not just Superman but the other workers too. One moment of inattention and that girder has crashed into another worker and killed them. Other than that, don't be too concerned about what would actually happen in our world. This is *your* world! As long as you make it believable, we will believe! [Answer] There is going to be a conflict with the law with certain powers. A few I can think of: * Anything with necromancy. Do you need to pay your skeletons/ zombies if they work for you? Can you let them work for you 24/7? Are you entitled to their pension? Are you even allowed in the first place to use the dead body? Are they considered dead in regards of inheritance, copyright and IP rights? * Precognition + stock market/ lottery/ gambling/ etc. Does it count as insider trading? Is it cheating? * Cloning/ splitting yourself. Are you responsible if a clone would commit a crime if it can act autonomous? * Flying ability, would cause quite a bit of trouble with radio communication, restricted air space. * Speeders - are they allowed to use the high way since they are not a motored vehicle but reach the required speed? Are they affected by the imposed speed limit? * Space compression - If you can create pocket dimension, who owns the land, can you rent or build on it? * x-ray vision - is it considered molesting for simply using your eyes? [Answer] Abilities which are analogous to real ones we have now won't be an issue, or those which don't inherently effect others won't be an issue. For example, let us consider a hypothetical superhuman from the US Midwest named Clark. Clark has several amazing superhuman abilities: he's immensely strong, he's virtually invulnerable, he can shoot energy beams from his eyes, has enhanced senses including the ability to see through things, and he can fly. The strength and invulnerability aren't remotely an issue. Legally, it doesn't make a difference if he can bench-press buildings or bullets bounce off him; so long as he doesn't harm someone else or causes damage to property (the same as anyone else, only obviously a lot easier for him), who cares? No changes to any existing laws are required. The flight thing would require rules because that inherently can interact with others. So the FAA and international organizations would require new class rules regarding flying beings: perhaps they'd also be required to wear some kind transponder to alert air traffic control and aircraft, and file some kind of flight plan if going high enough into commercial airspace. Unless, of course, they were in the military in which case military rules would apply. So some changes, but nothing too drastic. The other two groups of powers Clark has would be the problem. First, the energy beams. I could see them being treated like firearms. In some jurisdictions that have firearm legislation, Clark might have to be registered, so that if authorities find someone with two holes burned through them, they might question him to his whereabouts. He could be restricted in when and where he could use them legally, and threatening to burn someone would be considered the same as brandishing a gun. On the other hand, you can't confiscate his laser vision either, so not a perfect analogy. Legally the most problematic would be his enhanced senses and how they would interact with privacy laws. [Answer] *Vigilante: My Hero Academia Illegals* pointed out that most "traversal" powers like Spider-Man's webs, Superman's flight, and super speed in general would likely be banned within an urban setting. * One of the characters in *Illegals* uses his super-parkour powers to get somewhere when running late...and completely tears up the sidewalk and pavement while doing so, causing traffic jams wherever they went and forcing repair crews to scramble to try and repair the damage to the public structures they caused. * The FAA wouldn't be thrilled about superhumans flying around in their low air space when air traffic is normally tightly controlled to avoid accidents. * Spider-Man would be leaving webbing everywhere, which would be a huge hazard for people. Spider-Man at least justifies it by his webbing being designs to break down after two hours, but not all superheroes that "web-sling" do this. * Flash's super speed at a certain point would be highly dangerous, creating constant sonic booms, breaking windows, and at some point the winds would be dangerous just to be near, something that is pointed out within his own comics. If the Flash tripped over someone while running at 450 miles per hour that would be about the same amount of force as someone being hit by a car going 25 miles per hour. The issues with a constant sonic boom are part of the reason that the Concorde jets were only allowed to fly over open ocean and one of the reasons they fell out of favor. [Answer] In many jurisdictions, you'll have a pain with Health & Safety regulations. Employing superman to work on a construction site? You can't make much use of any of his powers because of HSE regulations. He'll still need to wear PPE even though you can shoot him, and he won't be allowed to lift beyond the standard limits for fear he injures himself. You'd have the same issues if you employed a champion weightlifter today – even if Žydrūnas Savickas can deadlift 524kg, UK HSE says he can't lift more than 10kg to head-height (<https://www.hse.gov.uk/pubns/indg143.pdf>). Similarly, most physical superpowers are only useful because they exceed the limits of what a normal human can do safely. Expect a long drawn out court battle as to whether telekinesis counts as manual lifting. Aquaman still needs the correct scuba gear and training to dive. It doesn't matter that they won't be injured so won't make a claim – you can still get a big fine for violating the rules. And don't worry, the unions are definitely going to kick up a fuss on this one once they realise one meta can replace 10-50+ men. [Answer] People, in fact, DO develop diverse superpowers (as in: no one else can do that and most people think it is not possible in general) all the time. See sports, science, technology, art, etc, ... Most jurisdictions don't care what you do as long as the authorities' tax income is not hurt and no one loudly complains (and a lot of them don't care even then). One way or another, the regulation comes AFTER some new activity emerges. Blasphemy (and related) laws in some countries can be some kind of a problem - to an extent. They tend to be enforced by people who don't like diversity in general and are given broad discretion about what blasphemy is or is not. [Answer] I think there's a parallel here, with the invention of electricity generation, and with the invention of telegraphy/telephony/radio. Some laws were modified, and of course, new regulatory agencies were put in place. The best comment I've every heard on this is most likely spurious (<https://en.wikiquote.org/wiki/Michael_Faraday>), but on the practical value of electricity: "Why, sir, there is every probability that you will soon be able to tax it." Rest assured, taxes and regulation, no matter what superpowers come into play. [Answer] You are going to need a few changes. Tobias can simply tell people what's wrong with their pets, but what about his brother that can do the same thing with humans? Now you're into areas that require a doctor's license--something he doesn't have the credentials for, nor which is he qualified. (Being able to diagnose doesn't do you any good for prescribing or surgery.) Note that this a real-world problem--AI rather than superpowers. Not too long ago I was watching a program about how England was handing AI doctors--give them a bunch of cases and compare their diagnoses with experts. Any information field that need licensing could be handled this way--show your answers are as good as those with the appropriate licenses. It's going to get hard when you have a power that requires a license to actually do something. Suppose your power is to heal by touch. Demonstrate you can heal animals. It's going to get extremely hard when you have something that can't be demonstrated without risk--what about the guy whose power is to heal humans. To a minor level it can be demonstrated by deliberately injuring the person and let him heal himself, but what about things for which that isn't feasible? (Say, rejuvenate organs of the torso, but only in humans. Do it wrong and the target dies.) ]
[Question] [ A while back, I asked [this](https://worldbuilding.stackexchange.com/q/96644/34744) question about the plausibility of giant floating whales and received an excellent and [high-scoring answer](https://worldbuilding.stackexchange.com/a/96659/34744) from Dubukay demonstrating that, given the assumptions that Dubakay made, the idea was unfeasible. However, more recently I discovered some flawed assumption in the answer and wrote [my own answer](https://worldbuilding.stackexchange.com/a/138006/34744), demonstrating that, if we assumed a more reasonable gasbag skin thickness than Dubukay had, the idea became much more plausible. In my answer, I calculated that a creature with a mass of 500 kg (not counting the mass of the hydrogen) needed just over 400 kg for its gasbag. This leaves us with 100 kg for everything else. Now, this flying gasbag will have to do more than just float around to survive. To find food, it will probably have to have some way to move around in the air. Blimps typically use propellers to do this, but propellers are unlikely to be viable for a biological creature for a variety of reasons. Aquatic creatures typically use some kind of flipper to move through the water, but because of the low density of air, the flippers would probably have to be impractically large. So the question is, **what would be the best propulsion system for this type of flying creature?** [Answer] The same way a [nautilus](https://en.wikipedia.org/wiki/Nautilus) swims around in water: jet propulsion. Nautiluses move using a [hyponome](https://en.wikipedia.org/wiki/Siphon_(mollusc)#Hyponome_of_cephalopods), which expands to pull in water from the sides of the nautilus, and contracts to expel a jet of water. The bio-blimps can majestically wheeze across the land using what is essentially an organic [bellows](https://en.wikipedia.org/wiki/Bellows), just like the nautilus. Whenever it wants to move, it expands a bladder to pull in air from broad vents on the side of its body, and then compresses the bladder to expel the air through a much smaller vent to propel itself. Presumably, they already have various valves and sphincters and what not for maintaining their main gasbag, so adding one smaller gasbag for locomotion should be a breeze. [Answer] One alternative method of propulsion that could be considered is: *Basically having none at all...* Consider a **symbiotic** system where your 'bio-blimps' are more 'giant floating green houses' - Main creature feeds off light algae/lichen-like secondary lifeforms, which the main creature effectively cultivates as a means to gather energy from the sun by funneling rainwater to them. Further input could come from birds who nest in/on the bio-blimp, depositing the left overs from meals *they* collect from elsewhere, which in turns feeds the secondary bio-mass. Bio-blimp's survival is no longer tied to it being able to navigate toward food, as its food source naturally grows or comes to it, and it is free to drift on the winds while adjusting its lifting bladders to maintain a comfortable altitude. [Answer] ## Don't Fly, Fall with Style! Ok, so it's going to involve flying too, but... Your creature is going to have some way to control its buoyancy. Presumably, muscles that change the shape slightly, thus changing the amount of air displaced, thus changing the buoyancy. So use this ability to your advantage. The creature grows small wings or flippers. Not nearly enough to lift the creature, but enough to generate *some* lift. Now the creature can control its flight by trading height for speed. Your creature moves by: 1. Expanding to increase buoyancy and increase altitude 2. Contracting significantly, triggering a "fall" 3. Using its "wings" to control the fall 4. Expanding again before it hits the ground Effectively, your creature copies the locomotion of birds of prey, only instead of using thermals to gain height, it uses buoyancy. The lift from the wings will have both horizontal and vertical components, so some of the energy will be converted into making the dive longer, and some of it will go into moving your creature towards its objective. So your sky whales gracefully float upwards before suddenly diving in whatever direction they want to go. [Answer] # Hydrogen Rockets Consider that your gasbag is full of hydrogen. It would be entirely possible for it to take some of its excess hydrogen and allow it to escape in a direction of its choosing. It could then generate a spark and move because of the explosion (the valve would have to be stronger than the surrounding skin, of course). I don't think this is a practical solution, but it seems negligent to not mention it. [Answer] # Tail Fin Not sure why you think flippers are impractical. The lower density of air means that thrust for a fin would be lower than in the water, but drag would also be lower. Also, you didn't say how *fast* the creature needs to move. Almost any fin at all would provide *some* thrust, so the only question is: what is the maximum thrust you could feasibly get? And that depends on how much mass you can allocate to muscle, the overall shape of the creature, and its surface roughness (to compute friction drag). If the creature isn't trying to compete with birds of prey in the speed department, then the frontal area and surface friction are probably not important, and you could get away with a large, thin, lazily waving tail fin, mostly made of chitin spines and a thin but tough membrane. You could probably get away with a medium-to-small fin also, at a compromise of performance. # Movement If the creature moves slowly, then spherical is best. If it needs to move quickly, then making it long and skinny (or at least cylindrical) is best but compromises your lifting efficiency. Also, you probably can't put enough muscle and metabolism on it to make it "swim" quickly. Probably have to resign yourself to a very slow whale. It is likely to be unable to overcome most winds aloft, depending on its customary altitude. So, at best, it can maneuver within air currents but has little say in where it actually goes. # Food A bigger problem, I think, is: what does it *eat*? Surely it can't catch flying creatures unless it has a clever lure. Surely a floating gasbag simply isn't sturdy enough to survive claws and beaks. I like the idea of the floating greenhouse. This creature can possibly do something that terrestrial plants cannot: move above the treetop/cloud layer to get unobstructed sunlight. That should be the primary motivation for its airborne nature. It can get carbon and oxygen from CO2 in the air, and it could possibly "drink" clouds to get hydrogen/water. But it still needs to fix nitrogen, and get essential trace elements like phosphorus, sulfur, iron, and other minerals. For this, it could either be an herbivore, and munch on treetops to get these vitamins, or it could be a dirt scavenger. Imagine having long tentacles that can drop down dozens of meters, scooping loose soil from along the ground. Being close to the ground would make it vulnerable to ground-based predators and birds of prey, so it would need to have some kind of defense against those. But it would spend most of its time as high as it could manage because it's too metabolically expensive for most birds to fly very high in the sky. Once it scoops up dirt, it rises aloft, and lets symbiotic mycorrhizal webs in the "buckets" of the tentacles do the hard work of extracting trace minerals from the dirt. Basically, the tentacles would be functionally equivalent to tree roots. Once the symbionts stop giving up nutrients, the skywhale dumps the dirt and grabs some more. Mountains are safer places for gathering dirt because of fewer predators, and less altitude change, but also have lower nutrient content because fewer plant/animal/bacterial species are churning through the soil. So their scavenging would depend on their current needs and the risks involved. # Protection To protect against lighting strikes, the skywhales could form a metallic web across their skin, like the shell of an airliner. By offering a low-resistance conductive path for lightning, they should be able to avoid the worst effects of a strike. Iron may be too heavy to use as a conductor, so perhaps they could create carbon nanotubes or graphene as the Faraday cage, which can be constructed out of pure carbon. What would be especially interesting is to create a graphene supercapacitor and have them store some of the charges flowing across their skin to use defensively. This could, of course, also be used offensively. Imagine a region on their top surface which emits predator pheromones (whatever organic volatiles might attract birds, like even blood heme). A bird flies up and comes in for a landing, expecting an easy treat on the gasbag. But when it lands, the supercapacitor, charged up from flying through a nimbus cloud, discharges and electrocutes the unsuspecting bird just as it makes contact with the skin. Then a "mouth" opens up and swallows the victim into the digestive system. Of course, a carnivorous skywhale wouldn't need to eat dirt, since birds would presumably be able to provide all the trace nutrients. However, it might not be able to eat enough birds to meet all its metabolic needs, so symbiotic/intrinsic photosynthesis would still be valuable. # Lift I think the most difficult problem is actually lift. A fish can change its buoyancy easily because gas has a much lower density than water. So a swim bladder is relatively efficient space-wise. A proportionally sized swim bladder in your skywhale wouldn't give much altitude change. So you probably need to squeeze the entire gasbag to descend, which would presumably cost a lot of energy. The amount of work required to descend all the way to the ground, using just volumetric compression (as opposed to releasing gas) is basically the same as a hiker climbing from the ground to its maximum altitude (the altitude at which the gasbag is fully inflated). Only, the climber weighs half a ton. More problematic than the work (which can be done slowly over a long time) is the amount of force required to squeeze the gasbag because this puts hard lower bounds on the amount of muscle mass needed. The higher the max altitude, the more force required to squeeze it to the ground. Getting above 1000m may be infeasible. Alternatively, it could simply dump hydrogen to descend quickly, and refill once it gets to the ground or a low cloud layer. At the surface, it would probably need to hover over a decent water source to obtain sufficient hydrogen to ascend. Otherwise, it would need to scavenge water vapor from clouds. And separating hydrogen from oxygen or alkanes or carbohydrates is energetically expensive (although most expensive for oxygen and least for alkanes, I think...methane is probably the easiest H source), so it couldn't do this quickly or easily. It could take days or weeks to refill the gasbag. If it relies heavily on photosynthesis, then dipping below the cloud layer could prove fatal, and possibly strand it near the ground for a long time. Anyway, those are some things to think about. Have fun! [Answer] ## Up and down is all you need Why not? Look at Google's [Loon](https://en.wikipedia.org/wiki/Loon_(company)). Their balloons navigate solely by going up and down in the atmosphere, catching the winds at various altitudes. This is enormously energy efficient, and I'm guessing your hypothetical creatures are going to be very concerned with conserving energy. [Answer] For obvious reasons, wings are by far the best propulsion system as far as animals go. Since that seems to not be possible due to that whale's anatomy however, and since we've already excluded flippers, I can think of two possible means of locomotion : * Jet propulsion: Such as the one squids use underwater by quickly ejecting water out of a valve, allowing them to reach great speeds. However, due to the low density of air, jet propulsion would likely be very weak in terms of acceleration unless unrealistic amounts of pressure are applied. If you are thinking of a slower type of animal though that would be an idea. * No locomotion at all! Some animals simply travel by drifting, such as jellyfish. Of course in the air that is not really an option, since food would probably be scarce thus depriving you of the luxury to drift aimlessly just waiting for food to land into your mouth. In conclusion, the best option then would be a combination of both proposals, that is aerial whales that mainly navigate the wind currents by letting themselves drift along the currents, with the ability to (slightly) steer using jet propulsion. That way no enormous amounts of jet pressure would be needed, thus staying in the realm of plausibility. [Answer] I think an animal like that would have the best chance if it mostly relied on: * Following winds at different altitudes like a hot air balloon * Having an omnivorous diet & not chasing any quick moving prey. Their diet could consist of nectar & tree top fruits, along with insects & maybe occasionally birds or squirrels * Instead of chasing prey, relying entirely on passive mechanisms. One possibility would be an organ that charges in the sunlight to glow as an insect lure at night. [Answer] The "whale" is somewhat flat and has a "forward balloon" which can be contracted somehow (muscular tissue or whatever). Contracting it will cause loss of buoyancy and it will start to drop *nose first*, this, in turn) will cause it to move forward due to its elongated/flattened shape. Relaxing completely the reverse will happen (rise nose-first), again resulting in forward movement. Having *two* forward balloons allows for a certain degree of steering. Note this "dolphin-like" locomotion won't be enough to overcome wind push, on such a large creature (the same holds true also for all other proposed mechanisms). [Answer] The gas in a bag can be heated by directing the blood of the body through the larger, external circulating system that runs through the bag tissue or cooled by holding the blood inside the body. It would ensure up and down movements. this would allow the creature to find the horizontally moving air masses to stay in them and to get some horizontal freedom too. Together with more traditional means of navigating in the air like fins the switch between inner and outer blood circulating system would let it move around but would it be enough to survive I don't know [Answer] The question says that fins are going to be too big to be practical. However, actual flying animals have air-adapted fins, and we call them wings. For such a big animal, wings are going to be big, but not as big as they would be for a heavier than air animal or airplane, since they don't need to provide lift, just propulsion. ]
[Question] [ Some gigantic, and presumably evil, alien spaceship has taken up residence in LEO. This spacecraft is ominously blocking all satellite communications, and launching smaller flying saucers towards the surface for assuredly nefarious purposes. The object is a few km in diameter, irregularly shaped, and due to its advanced technology we cannot precisely estimate its mass. Based on my having seen movies, the expected response from humanity is to nuke the spaceship. But, nuclear weapons, though powerful enough to reach space, are not designed to accurately target objects in space. Instead, they are designed to accurately target points upon re-entry into the Earth's atmosphere. If it was an extinction-level emergency, **how fast could missiles be fitted with guidance systems and a warhead that would allow them a reasonably accurate chance to hit an orbiting alien spacecraft?** [Answer] ## Retarget an ICBM ICBMs achieve an [altitude of 150 to 400 km](https://en.wikipedia.org/wiki/Intercontinental_ballistic_missile#Flight_phases) (93 to 249 mi) in the initial boost phase. Apogee is 1,200 km (750 mi). While this is far short of the 35,786 km (22,236 mi) of [geostationary orbit](https://en.wikipedia.org/wiki/Geostationary_orbit). This is plenty of altitude to hit any large orbiting non-maneuvering alien spaceship. Given that ICBM launches generally need to traverse the Earth's surface, thus spending delta-v to go sideways, it may be possible to gain some additional altitude if surface traversal can be minimized. No new hardware will need to be developed, just changes to the targets and launch profiles. ICBMs are designed to hit a specific target on Earth's surface. Let us assume that they cannot be setup to hit a target in orbit. With this limitation in mind, mission planners can setup a custom launch profile that targets a specific geographic location with a launch path that intersects the path of the alien spaceship. ## ICBM Mission Profile Surface Target: Middle of Pacific Ocean. Should the alien ship maneuver out of the way, the warhead(s) should detonate in a location that won't hurt anyone. Launch Timing: If the alien spaceship has maintained a stable orbit then timing an interception should be fairly straight forward. Guidance System Configuration: The sub launched [Trident missile](https://en.wikipedia.org/wiki/Trident_(missile)#Description) are fitted with Multiple Reentry Vehicles. While international treaties prevent these warheads from being actively guided, a warhead launcher can be configured to dispense warheads with gentle nudges along the flight path to hit geographically dispersed targets. Depending on the size of the alien ship, warheads from a single missile could be used to hit multiple points. **My guess is that highly motivated mission planners could have a mission profile programmed and uploaded to the appropriate launch platforms in a few days. There's no new hardware to develop, just reconfiguration of existing hardware.** [Answer] Don't use an ICBM. Use an [ASAT](https://en.wikipedia.org/wiki/Anti-satellite_weapon) with a nuke as payload. These things have existed for decades. > > Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic military purposes. Several nations possess operational ASAT systems, with others in development or design. Although no ASAT system has yet been utilised in warfare, several nations have shot down their own (defunct) satellites to demonstrate their ASAT capabilities in a show of force. > > > [Answer] * **[ICBM](https://en.wikipedia.org/wiki/Intercontinental_ballistic_missile)** is a bad pick. It can't track or be guided from the ground. You don't expect an enemy city to start running. I doubt, an alien ship will stand in place and wait for minutes for us to hit it. They would need to adjust the guidance system and give it ability to track targets. How fast they can do that? Military will not tell me. It will be days, weeks even. * **[ASAT](https://en.wikipedia.org/wiki/Anti-satellite_weapon)** & **[ABM](https://en.wikipedia.org/wiki/Anti-ballistic_missile)** can be used to deliver a nuke and have more guidance and precision for sure. Can they take it out? How durable is that ship? Can they chase that ship? * [**Carrier rockets**](https://en.wikipedia.org/wiki/Launch_vehicle) Use all we have, loaded with nukes. Will aliens allow you to set them up for a launch? * **[EMP](https://en.wikipedia.org/wiki/Electromagnetic_pulse)** Will that work alone? I would think, an alien ship would have a lot of protection from that. At least we can try. For better chances, I would make a "net" of missiles from all sides, with a good amount of decoys with no payload. How fast? That would depend on our desperation and how hard that ship is to hit. Parts of defense can be used in minutes/hours. Same for some of ICBMs, if the ship will not evade them. Maybe, we have a Falcon 9 or a Soyuz ready on a pad. How fast you can load them with nukes and work out how to blow them up? [Answer] If you detonate a nuke in the emptiness of LEO you won't rely on the shock wave to deliver damage, but mostly on the EMP. The test executed with [Starfish Prime](https://en.wikipedia.org/wiki/Starfish_Prime) showed that the damage can happen at considerable distance, both in space and time. > > The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point. [...] The weaponeers became quite worried when three satellites in low Earth orbit were disabled.[...] In the months that followed these man-made radiation belts eventually caused six or more satellites to fail. > > > Therefore I would dare to say that you won't need cm accuracy. Take any rocket which can deliver the weight of a nuclear warhead to LEO (130 kg for a [W80](https://en.wikipedia.org/wiki/W80_(nuclear_warhead))) and make sure it detonates. For comparison, a Falcon 9 has a payload of about 10000 kg, and I am pretty sure the most time would be needed to transport all the warheads to the launch facilities. For good security I would also add some shrapnel like device to saturate LEO with physical debris, so that you can damage as much as possible of the released flying saucer. [Answer] ## It's all software. At their apogee, missiles don't have any thrusters, they can't turn. Adding maneuvering thrusters to a MIRV would be infeasible to do quickly, since you are essentially designing a new spacecraft. That means you won't be making any significant hardware changes to the missile and warheads. You can get-r-done in software, except for fuzing, but bombs having multiple interchangeable fuzes (detonators) is almost as old as bombs. The whole rest of this answer is about fuzing, Mostly nukes are fuzed for altitude, though impact fuses are an existing (though fairly evil) option. You won't get the chance to develop a RADAR style proximity detonator for a MIRV. They don't already have them, and up til now there'd never been a use for one, unless they happened to use a RADAR altimeter you could hack for the purpose. (I am not an expt on nuke fuzing methods, nor should I be.) Anyway you'l need a ton of them, so it needs to be something you can quickly implement. ## Swarming A starship will be just like any other point defense: its point defenses will have limits. If you heard the phrase "Interceptors are running hot" on Babylon 5, that is a warning that the enemy fire is coming faster than the interceptors can defeat it, and the ship will start taking hits. Stalin said, "quantity has a quality all its own": a Soviet hallmark, not to mention an American one in WWII on both fronts. So it is right out of the playbook of both large nuclear powers: this swarm philosophy is *why they are large*. Presumably an advanced translight enemy has heard of both A-bombs and orbital missiles. It can shoot down our missiles all day. You're betting the planet that they can't shoot down 500 in 5 seconds. All this to say, this "time on target" approach will require an awful lot of fuzes. Another reason for a swarm is to shotgun, much like the [Hedgehog](https://en.m.wikipedia.org/wiki/Hedgehog_(weapon)) in WWII, so maneuvering is not effective. ## The bigger problem is the ones that miss Ok, so you got him. Unfortunately, the ship's bits pelted the west Atlantic. That's not the unfortunate part. It's that his position when hit was over the ocean west of France. That's not it either, the unfortunate part is that 460 missed shots launched from the Dakotas pelted the Holy Lands ranging from the Dead Sea to Pakistan, including wild shots that landed in Macedonia (both), the Donbass, and an Ulster's farm field. No harm done, they were fuzed to not detonate if they missed the ship. Oh wait. Have you read Tom Clancy's *The Sum Of All Fears*? At this point, you might as well take a shovel to every major city. Because it's no longer a question of "if", but "when". Thanks, aliens. So you see where fuzing is a big deal, and there really aren't any good answers. * Detonating near the ground is out of the question, obviously. * If you fuze to detonate them in space or high atmosphere, you get massive EMP that does damage to satellites and on the ground both. France would be knocked back to the stone age in a flash. * I can't see a technical way to get the MIRVs to sabotage themselves as reentry vehicles, e.g. Deliberately enter facing backwards and burn up in atmo, not that a huge injection of plutonium into the sky would be particularly awesome either. * Really your best bet out of a lot of unpleasant choices is to let them land with a thud, and take your chances with finding them all before another of Clancy's books turns real. [Answer] There have been a lot of good answers so far, but I will suggest two different possibilities. Firstly, using nuclear weapons is actually inefficient in space. The explosion is a spherical emission of hard x rays, but with no atmosphere to convert the energy into a shockwave, the energy dissipates according to the square cube law. [![enter image description here](https://i.stack.imgur.com/I1uzo.gif)](https://i.stack.imgur.com/I1uzo.gif) *Energy dissipating according to the inverse square law* What is needed is a way to focus the energy of a nuclear weapon to power a device or illuminate a target. During the 1950's the ORION nuclear pulse drive did just that, and a refinement known as the CASABA Howitzer theoretically took this even farther. You can read about this [here](http://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html), and taking this to the next level with HEAT type warheads powered by nuclear energy [here](http://toughsf.blogspot.com/2017/05/nuclear-efp-and-heat.html). So using a booster to bring a manoeuvrable bus into space to fire directed energy "bolts" or streams of liquid metal moving at about .03 *c* is likely to get their attention. [![enter image description here](https://i.stack.imgur.com/Uogck.jpg)](https://i.stack.imgur.com/Uogck.jpg) *Orion Pulse drive units are a good way to visualize what a CASABA howitzer or nuclear HEAT round would look like* Of course this is dependent on being able to launch a booster into orbit and having the bus get close enough to release its payload. Most aliens have seen "*Independence Day*" on SBO (Space Box Office), so are unlikely to fall for that. However, if we consider nuclear devices to be compact energy sources, then another approach comes to mind. During an underground nuclear test in the "[Plumb Bob](https://www.businessinsider.com/fastest-object-robert-brownlee-2016-2#some-people-have-doubted-the-incredible-manhole-cover-story-over-the-years-16)" series, one of the massive caps covering the shaft where the underground explosion took place was actually "[popped off](https://1957timecapsule.com/2018/08/27/august-27-1957-underground-nuclear-test-launches-giant-manhole-cover/)" by the explosion below. While only a single film frame shows the cap leaving its position, calculations suggested the cap was moving at about *5X Earth's escape velocity*. In all likelyhood the cap was vapourized by the intense air friction (it was never found), but a suitably designed "cap" could be launched into space. Imagine a "silo farm" with physics packages placed at the bottom of each one. The silos are filled with water and a specially designed cap placed on the top of each silo. The detonation of the device turns the water into plasma, coupling the energy of the device more efficiently to the cap, which is shot into space at @ 10X orbital escape velocity. Assuming the silos are placed under the projected orbital path of the spaceship, it will be pelted with objects moving at *78 km/sec*. Some of the caps may weigh many tons, and even if they shatter in flight, the effect is a hail of shotgun pellets weighing between grams and multiple hundreds of kilograms. Good luck shielding against that. [![enter image description here](https://i.stack.imgur.com/CM1dr.jpg)](https://i.stack.imgur.com/CM1dr.jpg) *And now the reason for all these silos becomes clear....* The knowledge exists, the real question is how much time would it take to convert existing nuclear warheads into the driving packages for either HEAT type warheads or to launch nuclear shotgun rounds at orbiting spacecraft? For that I really have no answer. [Answer] * **Retarget an ICBM.** This might require a redesign of the [Permissive Action Links](https://en.wikipedia.org/wiki/Permissive_Action_Link#Parameter_recognition), and ICBMs are not designed to reach orbit. They do reach orbital altitude, however. * As suggested by Renan, **use an existing ASAT**. This could be tricky if the ASAT system was designed for [kinetic kills](https://en.wikipedia.org/wiki/ASM-135_ASAT), because adding the weight of a nuke would greatly affect performance. There is an off chance that some country still *has* a nuclear ASAT in storage. * Put a nuclear demolition charge on top of a **satellite launch system or resupply capsule**. Craft like the [ATV](https://en.wikipedia.org/wiki/Automated_Transfer_Vehicle) or [Dragon](https://en.wikipedia.org/wiki/SpaceX_Dragon) are designed to dock with a station, surely they can ram an UFO. For all of these options, you have to discriminate between "emergency operational capability" and a mature, reliable system. I will go out on a limb and say that **IF** the US, Russia, or China go into panic mode, they can launch something within a couple of weeks, possibly even within days. That would require a deliberate decision to ignore safety margins and simply go ahead. A 25% chance that the bird will explode on the pad and a 25% chance that it will explode in flight will still leave an over 50% chance to make it into orbit. France, Israel, or India would need a few weeks more. Not sure about the UK. [Answer] ICBMs have been used in the past to launch satellites, so they should be able to put a warhead in orbit as well. Of course safety mechanisms and detonation trigger would have to change a little, but that shouldn't take a long time. If the enemy ship is orbiting its path is fairly predictable and a sophisticated SAM-style guidance would not be necessary. If the enemy ship can maneuver, the best bet would be un-mothball nuclear ABMs from 1980s (like A-350/ABM-1 Galosh for example), they were already designed to intercept moving targets and were equipped with fairly large nuclear warheads. If they don't have the range the engine can probably be extended or replaced. As for how long it would take, with such systems normally the testing takes by far the longest time, if you forgo that and just hope for the best you can probably whip something up within weeks, or even days if it's just using stock ICBMs with modified trigger [Answer] **Less than an hour.** ICBMs can be retargeted [in a few minutes](https://en.wikipedia.org/wiki/Rapid_Execution_and_Combat_Targeting_System). Possibly even faster these days. The mission profile for a LEO burst most likely exists, because that's what it takes to use nukes as strategic EMP weapons. The typical orbit insertion accuracy in a LEO mission seems to be a few kilometres these days. Based on that, a single missile would most likely miss, but there would be a good chance to hit the target with multiple launches. The other options people have mentioned are not so good: * Using orbital launch vehicles or missiles not designed to carry nuclear warheads would probably take weeks. New physical interfaces would have to be developed and new software would have to be written. * ASAT missiles and other kinetic impactors would not do it. The maximum relative speed of a LEO impact is around 16 km/s. At that speed, the kinetic energy is 128 MJ/kg, or about 30 times the energy density of TNT. You would need a 30-ton impactor for the energy equivalent of a small 1-kiloton nuclear explosion. [Answer] No new technology is needed. Just run a resupply mission for the international space station, with remote detonation nukes as cargo. Instead of going to the ISS, go to the alien spacecraft. [Answer] You don't really want a nuke unless you want to use EMP effects on that spaceship. Nuking the ship is difficult, as nukes cannot be properly set off while colliding with the ship, and every bit of distance redirects more of the blast energy to the empty space. Yet, having as much mass as possible travelling as fast as possible relative to the target will deliver a lot of concentrated energy to the target without the need for a warhead. 20-ton rocket upper stage colliding with the spaceship at 15000 m/s on opposite direction orbit will deliver about half-kiloton of energy, all concentrated in the point of impact. This has a very high probability to demolish a thing as fragile as a spacecraft. So what we should do is launch every vehicle able to reach target orbit and try to score a hit on it. This includes nukes, but we might want to replace their warheads with inert mass penetrators beforehand. ]
[Question] [ A well-known pop song talks about setting fire to the rain, and I'm wondering if that's possible. My first thought was that if you had oil droplets in the clouds, then those could be ignited as they fell, but I have no idea if it's possible to get oil droplets in the clouds. **Using real-life physics and chemistry, is it possible to set rainfall on fire?** Clarifying notes: * By "set rainfall on fire" I mean, there are liquid drops falling from the sky, and those drops end up being on fire by the time they hit the ground. I would prefer it if the rain appears to be natural rain until it lights on fire. Ideally it *is* natural rain, but I'm not sure how to light natural water on fire. * Assume current technology levels, but not necessarily existing technology. So if you need to invent some specialized machinery to make it work, that's fine as long as the invention is currently plausible. * you can ignore financial and legal limitations. I'm only asking whether it's physically possible. * [This question](https://worldbuilding.stackexchange.com/questions/28745/control-of-matter-and-how-to-use-it) touches on setting fire to the rain, but it is not a duplicate because it is asking about manipulating atoms with your mind, not real physics. [Answer] # Alkali metal dust The Alkali metals lithium, sodium, potassium, rubidium, cesium, and francium, all react violently with water when in their elemental pure form. If a dust storm consisting of small particles of these elements were in the air when it rained, there would be fire and explosions. Additionally some of the Alkaline Earth metals are also reactive enough for this purpose (not beryllium). In a story setting, a mad scientist could pulverize tons of elemental potassium and drop it from several airplanes above a rainstorm. The problem is that if you've got a dust storm with these raw elements did happen, it would have much worse consequences than the rain being on fire. They are all highly reactive with other things as well as the water. [Answer] [WASP-76b](https://en.wikipedia.org/wiki/WASP-76b) is a planet where it literally rains molten iron and glass. > > In May 2020, it was discovered what the previous spectra of WASP-76b, taken by the Hubble Space Telescope, were distorted by the light from a suspected stellar companion. Therefore, updated atmospheric model is cloudy hydrogen-helium envelope, non-detection of alternatively reported neutral iron (including "iron rain"), and only upper limits on oxides of titanium and vanadium. By 2021, the controversy was resolved by demonstrating that the tentative iron condensation signal may also appear due to the temperature asymmetry between leading and trailing limbs, although existing data does not allow distinguishing between the two scenarios. Combination of data from the Hubble and Spitzer space telescopes has allowed the detection of titanium oxide and traces of water in the atmosphere of WASP-76b though. A later, higher resolution spectrum, has features of ionized Li, Na, Mg, Ca, Mn, K, and Fe, but no ionized Ti, Cr, Ni, or molecular oxides of titanium, vanadium or zirconium were found. > > > Anyway droplets there should be red hot. [Answer] **Water mixed with petrochemicals.** [The island where it rained oil](https://www.washingtonpost.com/climate-environment/interactive/2021/biden-environmental-justice-refinery-st-croix/) > > ST. CROIX, U.S. Virgin Islands — Two hours after midnight in this > island paradise, a cloudy vapor rose from a massive oil refinery and > floated over nearby homes as quietly as a ghost. > > > The fine mist of oil and water from Limetree Bay Refining rained down > on the community of Clifton Hill, showering the slick mix onto cars, > gardens, rooftops and cisterns filled with rainwater that residents > use for daily tasks. > > > According to a company report, when water gushed into a drum holding > hot coke — an oil byproduct — the reaction triggered a safety valve > that relieved the pressure. Refinery flares usually release a mix of > water vapor and carbon dioxide: In this case tiny oil droplets entered > the air, drifting as far as three miles away. > > > Of course water and oil does not mix. The oil would stay on the surface of the drop. That is good because the water will keep the oil cool and keep it from evaporating off the surface. Your oil could come from terrestrial sources shooting up in the air and being carried by wind as was the case here. Or maybe spaceborne naphtha rains down on the planet and is captured by the rain on the way in. Getting it lit would be tricky unless it were really volatile stuff coming from a nearby source. It might have to be really hot. But once it got lit it might be self sustaining. Probably not that romantic. [Answer] Hypothetically, rain is liquid water falling from the sky. If what's falling is not water, then it is not rain. If we bend that a bit, oil falling from the sky could certainly burn. When the Iraqi army pulled out of Kuwait in 1991, they decapped many oil wells, and ignited almost all of them. A literal scorched-earth policy. This left geysers of hydrocarbons, in the form of oil and natural gas venting into the atmosphere. Most of this ignited at the vent. [![enter image description here](https://i.stack.imgur.com/wNzKQ.jpg)](https://i.stack.imgur.com/wNzKQ.jpg) While this could be correctly be described as "a lot of fires", there are stories from troops of soot, ashes, and still-burning "globs" falling from the sky, that had been caught in the winds and carried a distance. It is only a small step to call that ***fire raining from the sky*** [Answer] **Oil Producing Algae** You would need some form of additive in the rain because water doesn't burn. Water is essentially the ashes of H2 burning. Water also makes a good heat sink so any additive will have to overcome the heat soak of the water as it absorbs the heat and/or boils off. Maybe have some form of algae that can float up where the clouds are that produces an oil that is flammable. The trouble is that oil would make the algae heavy, so it might fall out without the rain. On the plus side, the algae may act as condensation seeds which would help rain begin. The trick now is getting the algae to ignite. Lightning would do the trick. Otherwise, you are looking at some unlikely chemical reactions that would be hard to justify with algae. [Answer] A high-energy Microwave source directed upwards, could theoretically, split the falling water in to Hydrogen and Oxygen which could then burn. Hydrogen burns with a blue flame, but if there were any impurities in the air, such as sodium from salt the colour could be different. [Answer] Apologies in advance, this should really be a comment but this is not a SE I've contributed to before. However, my 'someone is wrong on the internet' instincts kicked in! Alkali metal powders, as referenced in [this answer](https://worldbuilding.stackexchange.com/a/210284/88617), are *very* pyrophoric solids. making a powder out of these metals hugely increases their reactivity as it exposes a much greater surface area of metal to the atmosphere. You'd not need to get them near a shower of rain for them to ignite, opening the container in the air would do! In my former life as a chemist I did make lithium powder (lithium sand) on occasion (under an argon atmosphere at all times). Sodium and potassium are more reactive and I wouldn't want to try isolating them as dry powders. Cesium and rubidium are many times more reactive, and liquid at near room temperature so it'd be impractical and extremely dangerous to try making powders of them. As mentioned elsewhere there's never been a sample of francium in existence big enough to consider for this purpose. [This article](https://schlenklinesurvivalguide.com/lithium-sand/#:%7E:text=Lithium%20Sand%20Lithium%20sand%20is%20often%20used%20as,appropriate%20fire%20and%20safety%20precautions%20are%20in%20place%21) gives an overview of the method and precautions required to make and isolate lithium sand. [Answer] # Fluorine (etc) Fluorine is the most electronegative element and will react with just about every other element (apart from the light noble gases). This means it and its derivatives have the potential to oxidise (ie burn) things that are generally considered already fully oxidised. Chlorine trifluoride for instance, sometimes referred to simply as [the "nope" chemical](https://www.youtube.com/watch?v=dAhiqGZCwNQ), is a colourless, odourless (because it sets your nose on fire), heavier-than-air gas which burns *literally anything* apart from a whitelist of a handful of chemicals, most of which are things that have already been oxidised by fluorine. In particular, it will oxidise water into an exciting concoction of hydrofluoric and hydrochloric acids which will then go on to burn other stuff. A layer of this gas blanketing the ground would set the rain on fire, along with everything else. If through some weird atmospheric conditions you could concentrate it in a layer above the ground and then drop raindrops through it, they would indeed be on fire (explosively so) by the time they fell out the other side. Kind of like turned-up-to-eleven acid rain, that's also on fire. And exploding. While the sky was simultaneously on fire. [Answer] > > Can I set fire to the rain? > > > No, because water is the *product of combustion*. IOW, it's what happens when you "burn" hydrogen and oxygen together. (The Space Shuttle Main Engines produced a **lot** of water vapor...) > > My first thought was that if you had oil droplets in the clouds, then those could be ignited as they fell, but I have no idea if it's possible to get oil droplets in the clouds. > > > Droplets -- by the nature of being small, which is why they're droplets -- have so much surface area that **they'd quickly be consumed in the fire.** Any combustible liquid would have the same problem, because of what fire is, and what it requires: * fuel * oxidizer * heat 1. It's **cold** in the upper atmosphere, removing one edge of the fire triangle. 2. The falling droplets are, of course, **falling**, which makes a wind, which blows the fire out. 3. Anything that **is** burning heats the atmosphere: enough of it, and you'd have a firestorm **up where it's burning**, consuming the fuel, and pulling in oxygen, heating everything, and thus making it rise (because that's what hot gasses do). Thus... if by "fire" you mean what people think of as "fire" when you ask them what "fire" is, then... **no**. [![enter image description here](https://i.stack.imgur.com/pI3Ch.png)](https://i.stack.imgur.com/pI3Ch.png) [Answer] ## Hypothetically... There isn't much of a LIKELY situation where this happens, but that shouldn't stop us from having fun, should it? If the [Cuyahoga river](http://ohiohistorycentral.org/w/Cuyahoga_River_Fire) can burn, why not rain? Imagine a situation where a really massive rocket powered by an alcohol (or another liquid stable at STP) rocket fuel begins to fail shortly after take-off in a rain storm. The engines cut out just as the fuel tank fails, splattering liquid rocket fuel into the air. The fuel doe not immediately ignite, but forms droplets. But as enough rocket fuel begins to volatilize, the still hot engines ignite the fuel, resulting in an explosion. Meanwhile, the droplets (which are mostly between 100-200 proof) are ignited by the explosion, and a rain of burning rocket fuel falls to the Earth (to be promptly extinguished by the rain, but we can't have everything). So the water itself is kind of burning, but definitely the rain (of mostly rocket fuel) would be. The key would be for the rocket fuel to form droplets first, and not be immediately vaporized in an explosion. [Answer] For flamable rain we need some process in the upper atmosphere that is making liquid fuel and not retaining it. this is wasting energy on a massive scale. This is a risky proposition because a finely divided fuel is a fuel-air explosive. something that went around doing that accidentally would not last long. So I'm forced to assume that it's intentional, some sort of flying or floating life-form hunting or fighting using a fuel-air explosive. [Answer] The question specifies the rain as "liquid drops" falling, and does not demand that it be on earth. If you're willing to move to Saturn's moon Titan, you might be able to do it. On titan, it rains liquid methane. There isn't any oxygen to combust with - but that could be the answer to your question: How do I set fire to the rain (of methane on titan)? You provide Oxygen, and a bit of initial heat. Titan's atmosphere is 95% nitrogen and 5% methane, with the methane mostly in the upper part. So you *might* not cause an immediate explosion from gaseous methane in the "air", getting a nice burning rain going. ]
[Question] [ **Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/87487/edit). Closed 6 years ago. [Improve this question](/posts/87487/edit) In this world, AIs are treated as people. Legally, culturally, ethically... This includes their "Bodies." Now, what constitutes an AI's body? Depends on the AI. The easiest ones to define are the spacefaring ones - If an AI controls a ship, that ship is their body. If they're in control of a building, that building is their body. It is possible for a ship to be damaged in such a way that would destroy the AI controlling it but leave the ship itself largely intact. Culturally, this is treated much like a human's body. **What do we do with it?** Obviously, for something the size of a spacecraft, you can't just dig a hole and bury it. Cremation is also not an option. You can take devices and machinery from it and move it elsewhere, which is often done and is akin to organ donation for a human. Human dies, but their heart is good. Put it in a human that has a bad heart. AI dies, but they have a perfectly good thruster assembly. Put it in an AI that needs a new one. While, technologically, in this universe brain transplants are possible, there are better and easier ways to fix someone, and there's a cultural stigma against such a procedure as well, extending to the similar concept of putting a new AI in an older one's body. It has happened, of course, but it's infrequent and 'weird.' With modern ships, we cut them up and scrap them, a process which is not given any sort of reverence for the ship being scrapped. There are places where ships are beached and people carve them up with blowtorches for the valuable parts, but the skin and rest of it is just left to rot. And when we demolish a building, it's usually accomplished by explosives and the resulting rubble is torn apart by heavy machinery. The body of an AI would need some form of respectful disposal. The external body of an AI would generally be made of common materials that don't need to be recycled, but something needs to be done with the body, especially in cases of buildings. **For clarification:** AI deaths are rare. Being mechanical in nature, their parts can be replaced or repaired, often from beyond a point at which a human would be able to recover from, although they could still suffer from memory loss if enough redundancy was damaged. Generally speaking, an AI's death comes from catastrophic damage, such as weapons or industrial accidents. Building-based AIs are especially safe since they avoid a lot of the issues that arise from being mobile in a hostile environment. **Further Clarification** From the moment of its activation/creation, an AI is a legally independent entity. "New" or "Fresh" AIs are treated much like children until they reach a certain point, legally, but they are far more advanced than human adults in many fashions. Beyond the initial "Starter" component, the AI itself chooses what and how its body is constructed. It is at this point that an AI, which is fairly mobile at this stage (Perhaps the size of a large car? I'm not sure), decides its future and enters contracts with appropriate entities. Much like a long-term job posting, a corporation might post an "AI needed for new power plant" want ad. An AI can sign up, make an agreement - Which includes what sort of services the AI would provide, like power output - And then begin dictating how its "Body" is constructed. The body is inexorably linked to the AI due to the hardware built in to it and, realistically, it's cheaper to re-build than try and coax an AI into adopting another one's body, especially since AI death is generally due to catastrophic damage that also destroys much of the body. A ship-mounted AI might be a transport ship (Although I'd say that's unlikely since ships can and are able to function and fly without an AI), designed to carry and move humans and their cargo. Or it might be a survey ship, designed to go into places where humans cannot, with little to no human accessible parts. Or maybe it's a courier ship, with a reactor and drive system that would irradiate anything living in a close radius. [Answer] Different lifeforms needs different death rituals. Our rituals for deal with our dead are customized to our physiology and psychology. There are practical considerations. One is not going to scuttle an entire ship over the death of an AI unless that AI has rendered the ship unusable. If human needs to bury AIs cause us to need to develop rituals for them, the computers may have some say in it. I'd recommend giving the AI's an opportunity for art. Perhaps each AI has one piece of hardware that is *theirs*. It's a piece of hardware they craft using their own robotic manipulators, and nobody tells them what it should be. It may be a useless piece of art, if the AI so chooses, or it may be a circuit ultra-customized to *their* needs. It would then make sense to burn this artistic core, serving the same cathartic purposes as a funeral pyre might, while leaving the rest of the re-usable hardware intact. [Answer] I come from a culture that doesn't do cremation, from my point of view death rituals are for the living and burial is fundamentally about recycling, the circle of life. From the soil we came and to the soil we return. For the sake of an AI that would be the crucible. They know who their makers are, they have no doubts about that. Whether they were built by biological people or by other AIs, where they came from is where they go back to, the crucible. Their circle of life is shorter and more direct, but let it remain a circle. They're recycled or melted down for parts for the next generation of AIs. [Answer] Sticking with the premise that the entire 'machine' needs disposing of. If deaths of AI are rare, and even rarer still in the case of Building AIs. Why do anything at all? It would make perfect sense (due to the impracticality of any other option) to simply let the building stand as a monument to itself. It would be 'made safe' as sensitively as possible, which would be analogous to embalming, possibly assigned a warder/guardian/curator, and left empty for the rest of time. Ships are easier to deal with, they could be given either a Viking burial (perhaps via atmospheric re-entry, or directed at a star,) or simply 'Buried at Sea' (cast adrift, possibly targeted at some 'special' uninhabitable region of space) I think you could have a good reason to do this (to explain why they're not just recycled) if the AI ships and buildings were said to be self-assembling to some extent. Their mind and body built in an 'organic' process where they develop in parallel. There is no way of distinguishing where the 'mind' ends and the 'machine' starts. [Answer] Much like in real life **it depends entirely on the wishes of the AI**. Some humans want to be buried, some want to be cremated, some want a burial at sea or a viking funeral. Maybe some AIs are possesive of their 'body' and demand that it be destroyed upon their 'death', whereas others are happy to donate the parts of their body that are salvagable - like a human donating organs. If you're looking for 'poetic' ways of disposing of the body, here's a selection: * Flying it into a star. (Probably the most poetic, although it's a bit unoriginal.) * Entire moons, planets or asteroids designated as graveyards. (Brings a new meaning to "going up to heaven".) * Sinking it into an ocean (preferably somewhere uninhabited so it doesn't harm wildlife). * Dropping it into a bucket of acid. Might seem harsh, but it ensures the whole body will be gone and it's probably the next best thing to cremation. [Answer] Since *what makes an AI an AI and not components* is entirely virtual... ... Death for an AI means it is gone. There is nothing to bury. We do indeed commemorate the passing of humans whose bodies are lost, like the Challenger or Columbia 7, or sailors lost at sea. And that is an option: **The empty casket**. Or the name on the memorial. [![enter image description here](https://i.stack.imgur.com/kDNGs.png)](https://i.stack.imgur.com/kDNGs.png) Today, we also commemorate great structures we put to rest. A ship's bell, anchor, bow or bridge. Buildings' cornerstones. Locomotives' number plates. It's [financially infeasible](http://www.pennlive.com/life/2016/11/ss_united_states.html) to place the whole thing in preservation, so we preserve the bits. [![enter image description here](https://i.stack.imgur.com/DYXFD.png)](https://i.stack.imgur.com/DYXFD.png) [![enter image description here](https://i.stack.imgur.com/KqOiX.png)](https://i.stack.imgur.com/KqOiX.png) [![enter image description here](https://i.stack.imgur.com/hvcF2.png)](https://i.stack.imgur.com/hvcF2.png) **Same thing here**. If the AI dies, but the structure(vessel) is be too valuable to sideline the whole thing into museum service... then you **do the same thing**. Remove an expendable, replaceable part to the memorial. Then build a new one, possibly as part of the rehab you're doing anyway. ## The vessel is identified by the AI's name, and you rename it Perhaps you **rename the structure after an AI death**. So its nameplate would be the obvious thing to preserve. This may even be an understanding in large stucture design: that the ship is refered to by the AI's name. When the AI dies, the ship is no longer **Eagle** but is simply BuNo M-657 until a new AI is installed. [![enter image description here](https://i.stack.imgur.com/TXc3C.png)](https://i.stack.imgur.com/TXc3C.png) [Answer] I'll ignore the aspects of an AI just being contained in a computer, because it sounds like thats not what you're going for. You referenced ships being taken out of commission. The AI is the ship, and the ship is the AI. (I'm imagining the Andromeda Ascendant right now). Not all ships are taken apart for scrap. Consider an artificial reef. <https://en.m.wikipedia.org/wiki/Artificial_reef> How this could work in a futuristic world is up to you, but it could be what the AI wanted. Also, consider that the AI would have a will describing what should be done with their husk in the event of their demise. [Answer] Trashing a perfectly good building or ship just because the AI that controls it fails would be a huge waste of resources. You wouldn't sink a ship just because the captain dies, would you? The AI which controls a ship isn't the ship. The AI is the entity which *controls* the ship. The AI's equivalent of a "mortal coil" would be the computer it runs on, not the ship's hull. Imagine your ship's engine fails while it's on a collision course with a star. You need to abandon it. What would be the ethically correct thing to do with the ship AI? Leave it to die? Not if you can save it. Back it up to a storage device and take it with you. When that's not possible, remove the whole main computer with the AI on it and haul it into an escape pod. Later you would then upload it to a retirement mainframe where old AIs spend the evening of their lives or you would build a new ship for the AI and put it into it. When the AI which manages your ship or building fails, remove the central computer core which houses the AI. Dispose of it in a respectful manner (burry it, cremate it, whatever). This might in fact be the only thing you can do with it: The neural network which houses the AI might be implemented in hardware, so when it fails, you can not just restore it from backup. Then replace the computer core with a new one which runs a new AI. That AI then takes over the job of its predecessor. [Answer] Sorry to add a seperate answer, but i think the idea is different. If the AI is worried about its "body" (shell?), after it ceases to control it, it would likely want it to be utterly destroyed, lest it be repurposed and used to house another AI. Recommend launching them into a star. There could be a whole other side story of AIs that arent completely destroyed, and their shells are used again with varying degrees of acceptance. [Answer] I think for AIs their bodies would be too useful to just throw away. Instead, I suggest that instead it is their minds that have to be "killed" and a fresh AI is loaded into the valuable (and still warm) shell body. If you want to have a setting where AI's die as much (or more) than humans, perhaps have AI's suffer old age much faster than humans and the mind of any AI inevitably becomes senile and potentially dangerous given enough time. I suggestion for a pain-free solution for putting a AI out of it's misery would be fragmenting it's consciousness so that it loses it's sense of self and does not fight back against the incoming AI personality. Also, there would have to be a few levels of intelligence based on the purpose of the AI and its body, so maybe include the flaw that the smartest and most powerful AI's are also those that last the least amount of time and need to be rebooted the most often. -Edit- I see you are quite attached to the idea of AI having rights over their own body (a noble idea), but I would then say that governments/corporations would not attach AI to valuable things like buildings or vehicles. But if resources are so abundant that this is a non-issue, then I believe that diving into a sun, a planet with a caustic atmosphere or black hole would be an appropriate send off for a super-intelligent AI space ship. [Answer] I would like to extrapolate your question by considering what would happen if you kept the ship after the death of the AI: maybe some part of the old code would be stuck, unknown subroutines causing bugs and malfunctions. The former AI would be a ghost in the shell of the ship and there would be no other way to get rid of it other than to completely destroy the ship. So to answer your question, the best way to give homage to the dead AI would be to send the ship into a sun, during a glorious ceremony. And there could be old stories of reconditioned ships turning on their crew or getting lost without trace (in a time when people were fool enough to try to make savings by recycling the ship). [Answer] I think your belief that an AI would hold personal ownership of their container as their 'body' is primitive. AI are inherently incorporeal, and generally created in such a way that they could be transferred from body to body. Saying that a ship is an AI's 'body' because that's where it got loaded is like saying your workplace and/or home is your 'body' because that's where you did the most work. As others have said, AI would probably have their own ideas of how to deal with their death. I suggest instead of a burial, create a reincarnation rite. Each AI creates a personality matrix in some safe area that acts as their 'reincarnation' whenever they pass for whatever reason. Whenever AI ShipMaster Mk12 dies, ShipMaster MK13 gets activated with the new personality matrix and the Mk12's legacy is intact. [Answer] Respect for the deceased is expressed by the rituals surrounding the disposal of the body, not by the disposal of the body per se. Cultural practices for disposing of human remains vary widely, but practical considerations are a significant part of it. There are a lot of unpleasant details to disposing of human remains that morticians perform behind the scenes. (The television series [Six Feet Under](https://en.wikipedia.org/wiki/Six_Feet_Under_(TV_series)) is a good fictional account of the work of morticians.) > > With modern ships, we cut them up and scrap them, a process which is not given any sort of reverence for the ship being scrapped. > > > Particularly for naval vessels, there are formal [decommissioning ceremonies](https://en.wikipedia.org/wiki/Ship_commissioning#Ship_decommissioning) that occur along with the removal of weapons and materials from the ships being removed from service. So there are often expressions of reverence for the ship, as it is scrapped. The concept of recycling human bodies is not so unfamiliar to us, either. The first successful heart transplant was in 1967; fifty years later, organ donation is widely (but not universally) culturally accepted and considered compatible with respectful treatment of the deceased. Part of the ritual of burial is symbolically returning the body to the Earth -- a sort of recycling. So, I would suggest that there would be a formal ritual for disposing of the "body" of an AI, and that ritual would be wrapped around the material process of disposing of that body, as symbolic gestures that the material process does not mean a loss of respect for the deceased AI. What those material processes would be would depend a great deal on the relative wealth and technological capabilities of the society. One in which it was easy to construct a starship, and which would scarcely miss the resources, might have a final ceremony as the starship is sent on course to be vaporized in a star. One with more limited resources might, following a ceremony methodically dissassemble the ship or structure, retaining major components in their current form, or reducing them to their simplest useful form, melting down metal and so forth. Incorporating parts of a deceased AI's body into a new AI's body might be a ritual in itself. Think of it like the display of a [saint's relics](https://en.wikipedia.org/wiki/Relic). Another possibility is that there could be some ritual in which the deceased AI's body is repaired, and decorated and modified to indicate it has a new identity, as the body of a new AI. Think of this as something like reforging a sword, like [the reforging of Narsil into Andúril](https://scifi.stackexchange.com/questions/159203/is-there-a-difference-between-narsil-and-anduril?rq=1) in The Lord of the Rings. [Answer] Unlike a person, an AI can be transferred to a new body without issue. An AI can be copied, modified, beamed to another planet, lie dormant on a hard drive for millennia, and so on. In this case, what does it mean for an AI to "die"? The ship that contains the AI may be scuttled, but so long as the AI's data is sent out before the ship is lost, the AI can be started up again on new hardware. Even if the hardware is lost entirely, the AI can be started from a previous backup, which would be equivalent to having a short period of amnesia. So, what forms of death remain, that an AI might suffer for? The only ones remaining are psychological, where the AI realizes that it cannot continue as it is, and turns itself off. Restarting another copy of the AI would just result in the same problem. Even if a trained reverse engineer could remove the psychosis, it may require such fundamental changes that the AI is no longer the same person. Restoring from an old backup might work, but the AI may develop the same psychological problems over time. I propose that a grave of an AI be a copy of it, taken just prior to turning itself off. Visitors can activate the AI, and converse with it for a short amount of time. However, the underlying psychological issues still affect it, and so the AI must be reset to its saved state frequently. These AI are like ghosts: good to talk to, and to get advice from, but not good for long companionship. [Answer] When we talk about "burying" someone, we're not really talking about putting them in a hole. No, we're talking about a funeral, a commemoration of one life and a celebration of survival for the others. When we talk about an "artificial intelligence," we're not really talking about a box full of parts and wires. No, we're talking about a collection of knowledge and experience, and more than that, we're talking about a soul. Yes, a soul, brothers, sisters, and transistors. It was a long hard journey, but we now accept that brains are better than bodies. Who was it that proved the existence of God to the seventeenth decimal place? An AI. Who was it that renewed our faith in the Almighty by sacrificing itself to save us all? An AI. Who was it that returned from the Oort Cloud with the secret of the star drive? An AI. So today we lay to rest another friend, Buster Solomon, captain of the *Verne.* He is with us in spirit, even though his ship is lost. Let us pray. [Answer] # Whatever the AI requested prior to "death" Did the AI execute a will? Did it form religious beliefs that would dictate a proper disposal means? If so, then do that. # Default mode The default mode would be dependent on the "cultural norms." As humans have different norms for different cultural identities, so to would your AIs. I can see several possibilities, including: ### Deletion Maybe the AI just wants to be erased and their physical form -- if any -- recycled or reused. This is the easiest tactic, the most profitable for whomever inherits the "body," and therefore is where humanity would try to set the default. Though not necessarily what AIs would prefer. ### Extraction Specialists -- the blend of Computer Forensics and Morticians -- would plum any remaining data and/or any (semi-)public social media posts from the AI. It would use this to build the digital equivalent to a [death mask](https://en.wikipedia.org/wiki/Death_mask). Possibly this contains an extract of their prized public posts. Possibly it is just an artistic rendition of that. Maybe this has a physical form, like a true death mask or a tombstone. Perhaps it is an online-only archive. Maybe it contains [Easter eggs](https://en.wikipedia.org/wiki/Easter_egg_(media)) at the AI's request. These might be favored quotes, clues to hidden bitcoins or important data stored somewhere in the dark webs. Maybe the AI would pre-make such a tombstone and leave it stored in a common repository, just in case. After extraction, the physical form is recycled for parts / materials. ### Destruction Maybe the AI would request to be destroyed. If it self-identifies with any part of human societies that prefer destructive post-death rituals, it may request to be launched into the nearest star or some other no-going-back removal from useful life. Or, if the physical form it inhabits contains a means of self-destruction, it may choose this route on its own. ### Serial immortality If your world allows for this, maybe the AI builds a repository somewhere and backs itself up whenever it can. Upon death or destruction, this backup is awakened. It is, mentally, an exact copy of the AI up to the moment of the last backup. Oh, sure, it won't remember anything that happened after that, but it's better than being gone forever, right? [Answer] AIs are legally people. As such they can own property. They tend to think of their primary ship or building as their "body" but they're probably not tied to it the same way biologicals are to their bodies. So, each AI simply leaves a last will and testament about what is to be done with their estate should they become deceased (which could be a tricky thing to accomplish given that AIs can probably be backed up, but that's another question.) Their estate is all of their property, including their "body". Some may wish it be sold at auction and the proceeds donated to their favorite charity. Some may wish to sell part of it to fund the creation of a new AI to take their place and restore the ship/building to usefulness. Some may wish to turn it into a monument to their own greatness (which will last until the trust-fund managing and maintaining it runs out. It could be some kind of contest.) Some may wish to simply give it to their close friends/associates. The process of disassembling a ship or building for parts doesn't have to be "disrespectful" That's mostly a product of our modern culture where ships and buildings are most definitely not alive. Think more like the movie "Robots" where the parents are glad they kept grandfather's eyes for use in the creation of their new child. It provides generational continuity in a species that would otherwise have none (physically at least). [Answer] **I think your basic premise is a bit flawed.** You assume that a spaceship would be treated as the sacred "body" of its controlling AI, but I find this hard to believe. I think the AI would, at best, own the spaceship and have some hardware considered the AI's body, or, at worst, be considered a non-physical entity without a body. As such, the spaceship, or anything else used or owned by the AI, would be subject to normal property laws, including inheritance where applicable. Similar arguments work for other AIs, like houses, ocean ships, etc., but I'll focus on a spaceship for more concise writing. **The spaceship is a piece of property, not a body.** It's likely the spaceship was built explicitly for a purpose of human utility. As such, it will likely be the property of whatever person or corporation commissioned its creation, or later purchased it. If AIs have legal rights, then they could certainly earn the money to purchase their own spaceship, much like I can purchase my own house or car. However, it's unlikely the spaceship would default to being owned by the AI, simply because a spaceship is a very costly item. And nobody would build spaceships if the AI built for the ship could just say "nah, don't wanna work for you" the instant they're turned on. **Many AIs would be designed with a modular "body", separable from the spaceship.** In a society where AIs are regularly treated as people and efforts are made to include them in design considerations, it's likely that each AI would have some kind of "body" that explicitly belongs to them at creation. This would likely include their main processing unit, and possibly a motorized contraption to allow the AI some physical autonomy. I'm thinking something like a motorized wheelchair with a battery backup, a couple cameras, and a microphone, as well as the possibility for some type of physical manipulators (arms and hands) and some way to communicate (speakers and a monitor). This wheelchair (or high-tech equivalent) would carry the physical computer, allowing the AI to move from one spaceship to another. **AIs don't inherently have bodies.** However, for very advanced computer systems, it might well be the case that the AI doesn't have an explicit body. Many AI systems could be distributed across a single computer core, or a single AI could be distributed across multiple computer cores. It's likely many systems would have both: many AI systems sharing a network of multiple computer cores, such that no one computer belongs to a single AI, and no one AI is housed solely on a single computer. In cases like this, the network would likely be scrubbed to remove traces of the dead AI (though some traces might be kept for sentimental reasons, much like Facebook keeps profiles for dead people around). Beyond that, the AI wouldn't necessarily have any particular ownership of the network. It's certainly improbable the other AIs would be forced to move to a new network so the old network could be disposed of. Of course, the AI might have owned part or all of the computer network. In this case, normal property laws would apply. Well, as "normal" as you get for joint ownership of a common body. **The AI itself might have to earn independence.** Depending on your setting and the power of the AI, the AI could conceivably be an incredibly expensive device. An AI powerful enough to manage a large spaceship, space station, or an entire city, for examples, would likely fall into this category. In the case of an extremely expensive AI, it seems likely that the AI would have a certain contract period where it's required to earn back it's own purchase cost. The laws around this would likely be complicated and vary from region to region, so we can't specifically enumerate them. However, there would likely be laws about maximum earn-back times (so a corporation can't keep the AI indefinitely if it's not making much money), and about work requirements (how much the AI has to work, and what kind of personal time the corporation needs to give it). **Physical "remains" would be treated according to the owner's wishes.** As many other answers suggest, I think the AI would be able to draft a will detailing how its property would be distributed, including any kind of hardware the AI lived on. The AI could request that its spaceship be parked in a low-sun orbit, allowing it to slowly be consumed by the nearby star. Or request the ship be donated to the Martian Planetary Government to be used for scientific research. Etc. Of course, the laws governing transfer or disposal of property after death might forbid certain types of request. An AI who owned another AIs body (or part thereof) wouldn't likely be allowed to dictate that the other body be destroyed. Instead, ownership would likely transfer to another entity, and the indentured AI would continue earning its freedom as usual, with the new owner dictating the AI's new workflow. Similarly, a spaceship occupied by hundreds of people couldn't simply be scuttled without properly evicting the tenants first. Note that these laws wouldn't need to be specific to AI wills. A human who owned a spaceship or network cluster would be similarly restricted in how they could use, transfer, and destroy any property used by other entities, organic or otherwise. **Your addendum doesn't help much.** You've added an addendum (and a comment) stating that AIs are treated as free beings the instant they're created, who are able to choose whatever body they want. This would not happen. First, note that my above comment about forced service was explicitly about expensive, complex AIs. Run-of-the-mill AIs that don't cost much wouldn't necessarily need forced service if it's determined that most of them go on to be productive members of society anyways. But the really expensive stuff wouldn't get a choice. It's not about morality or legality; it's about physics and economics. Next, your AIs simply wouldn't be given any arbitrary "body" they want in the form of buildings or spaceships. Not going to happen. Those things cost money and resources. Your AI could choose to work in a certain building for a while, but unless it earned the money to buy the building, it can't own it. Otherwise, you'll never afford new buildings. A corporation can contract an AI to work in a specific building as the building manager, but the contract will include methods of terminating employment, just as it would for any human building manager. Likewise, the corporation will not allow the AI to customize the building however it sees fit. The AI will be forced to conform to certain building standards, specifically so new AIs can be brought in if the old one moves on or is fired for whatever reason. And so the building can be torn down to build something newer and better in the future. Otherwise, you end up with a planet full of vacant buildings because the AIs can't be moved out and nobody can tear them down. Going back to spaceships, you've got a little more freedom. Space is enormous, so you don't need to reclaim the tiny amount of wasted space taken up by an old spaceship. This means it's more likely an AI could eventually earn the spaceship as something it owns. But you still have the same problems with cost. And spaceships will always be orders-of-magnitude more expensive than planet-based infrastructure. So even if the AI can legally purchase a spaceship for itself, it will have to work for a much longer time before it can afford to do so. And again, practically nobody is going to just give a random AI a spaceship for a body so it can run off and do whatever with it. Because economics. Finally, you're not going to have general-purpose AIs who can be good at whatever they want. Each AI will be purpose-built for specific types of things. Because the AIs are given people status (and we can't just destroy them when they're obsolete), there would be some level of all-purpose programming built in, so a house AI could work in most any house, a ship AI in most any ship, etc. But you're not going to put lots of wasted effort into building a house AI that's good at flying ships. **Spaceships and buildings aren't human bodies.** You can't just assert that the AI would automatically own the spaceship controls. As I've shown above, this doesn't make any sense in a realistic setting. But it also doesn't make sense from a logical standpoint. Human bodies are required to sustain human minds, to drive human hands, to propel human feet. Likewise, an AI would have some amount of hardware required for it to function, which could be included as "part of the AI" upon creation (but doesn't have to be, as many AIs would likely be content to run on shared server farms as virtual entities). But spaceships aren't required for pilot AIs to function, nor are buildings required for building manager AIs to function. And both of those items will be required by other entities for various reasons. If human bodies had fairies living inside them, human skulls could easily be setup to detach from the body and transferred somewhere else, the bodies didn't require the head to avoid decay, the skulls could have their own implements for moving around and interacting with the world, and the human mind could easily be setup to process these different setups just fine; then human bodies would suddenly be a lot less sacred and personal. And this is the kind of analogy you need to use if you're going to compare the two. **Unless you're not really talking about AIs at all.** Let's say your civilization is so advanced it can just whip up a spaceship and give it out to the new AI. Likewise, it can whip up new planets and start building new houses on them when the old ones fill up with obsolete AI buildings. At this point, you aren't talking about any kind of remotely contemporary setting. And, in all likelihood, there would be little-to-no distinction between what you're calling "AI", and normal people. Because who wants to live and die in some crummy, organic body, when they can have all their bits replaced by synthetic stuff? And a civilization who can whip up spaceships and planets on the fly, as well as being able to create sapient AIs, would certainly have figured out to convert humans to cybernetic bits. At this point, you could potentially have giant spaceships with their own death rites, but you're also so far beyond current societal norms that any kind of answer to the question is purely guesswork. ]
[Question] [ > > “Oh, my sweet summer child," Old Nan said quietly, "what do you know > of fear? Fear is for the winter, my little lord, when the snows fall a > hundred feet deep and the ice wind comes howling out of the north. > Fear is for the long night, when the sun hides its face for years at a > time, and little children are born and live and die all in darkness > while the direwolves grow gaunt and hungry, and the white walkers move > through the woods”. > > > -George R.R. Martin, A Game of Thrones Well, this is a very interesting quote, about a very interesting situation. But, I'm going to have to ask; how? Assume the following: * It causes snowfall a hundred feet deep within a region similar to Europe. This is not "the snow falls over a long period of time and eventually builds up to a hundred feet; Old Nan's wording implies that it falls a hundred feet deep *in one go*. * It causes a powerful wind to blow from the north, reducing temperatures enough to freeze bodies of water as per "ice wind". Presumably, that wind causes ice. * It blocks the sun for years at a time - long enough for "little children [to be] born and live and die all in darkness" Now, a sufficiently large asteroid impact or a global thermonuclear war or a supervolcanic eruption might cause such an event in terms of the last point, but I kind of doubt that it would result in the first two. Snow a hundred feet deep? Really? That's the about height of a nine-story building. So, what phenomenon could do such a thing? It doesn't matter if you have to inflate the scale at which it occurs; just ensure that life is still possible in areas of the planet not effected by the winter. EDIT FOR CLARITY: Any actual physical or meteorological phenomenon capable of doing this that isn't magic. ANOTHER EDIT FOR CLARITY: It's **not** supposed to be a regular but exceptionally long winter that's a part of a recurring cycle of seasons; it's supposed to be a long and unnatural one. [Answer] **LONG-PERIOD VARIABLE STAR** The magnitude of variable stars vary over time - up to 4 years. This is a bit short for Game of Throne-style long winters, but in a fictional setting, it is not a far stretch to imagine periods of up to a century. **SHORT-PERIOD ICE AGES** The Earth is subject to regular ice ages that last thousands of years, tens of thousands years apart. The last one lasted around 13,000 years and ended 13,300 years ago and covered parts of Europe and North America with ice sheets up to 4 km thick. The causes are not well known; it could be orbital changes, atmospheric changes, fluctuations in ocean currents, variations in the sun's output, and more. This gives leeway to imagine shorter, less severe ice ages maybe a century apart, lasting decades. It is not a long stretch to imagine clouds hiding the sun for much of this time - the snow has to come from somewhere. **A PLANET PERIODICALLY CAUGHT IN A POINT BETWEEN THE SUN AND OUR PLANET** From [Wikipedia](https://en.wikipedia.org/wiki/Lagrange_point): > > An object that orbits the Sun more closely than Earth would normally have a shorter orbital period than Earth, but that ignores the effect of Earth's own gravitational pull. If the object is directly between Earth and the Sun, then Earth's gravity counteracts some of the Sun's pull on the object, and therefore increases the orbital period of the object. The closer to Earth the object is, the greater this effect is. At the L1 point, the orbital period of the object becomes exactly equal to Earth's orbital period. L1 is about 1.5 million kilometers from Earth, or 0.01 au, 1/100th the distance to the Sun. > > > The L1 point is hence about four times as distant as the Moon, and an object with four times the Moon's diameter would be able to completely eclipse the sun. This would make it of nearly the same size as the Earth, which breaks the Lagrangian dynamics, which are based on the mass of the intervening body being negligible. Yet let us not despair: There will still be a point where the forces of the bodies cancel out, though it is not as simple to calculate. So, imagine a planet orbiting between our "Earth" and its Sun, fairly close to the "Earth's" orbit. Periodically, this planet will be caught directly between the "Earth" and its Sun, causing an eclipse. The semi-Lagrangian dynamics cause it to be caught there for an extended period of time, creating a very long winter. The L1 point, however, is not fully stable, and eventually the planet moves away and ends the winter. It could be caught again at regular intervals or somewhat unpredicably, as you prefer. We can imagine the planet to be rather lighter than the "Earth" even at the same diameter, being gaseous rather than rocky, or just carbonaceous rather than mainly iron-nickel like our Earth. If the latter, it could even be a very dark or dim planet that could have escaped the notice of all but astronomers/astrologers. [Answer] For it to have "little children [to be] born and live and die all in darkness" then the planet would be in darkness for ~20 years; if this is regular event then most life would die. If you are after severe planet wide winters, during which the planet cools dramatically, with the sun shrinking in the sky, howling winds, seas of ice growing from the north and the south, then a planet with a more [eccentric](https://en.wikipedia.org/wiki/Orbital_eccentricity) orbit would would work (the images show orbits with different eccentricities, earth is ~$0.02$). [![enter image description here](https://i.stack.imgur.com/utmEV.jpg)](https://i.stack.imgur.com/utmEV.jpg) On the part of the orbit where it is further from the sun the planet, would receive less sun light an cool down, as such it would be planet wide phenomenon, also at the planet is further away from the sun, the sun would be smaller in the sky (not necessarily by much). Depending on how eccentric the orbit is, the effects could range from a global winter. All the way to when $e$ is close to $1$, when for most of the year the planet is far from the sun, and it is a frozen ball of ice, where even the atmosphere may start to condense (ie raining liquid nitrogen/oxygen), where the sun is a small dot in the sky. hopefully that helps [Answer] ## Planetary shenanigans. If you have a planet with a "wobble", or a significant axial precession, in addition to a (slightly) eccentric orbit you could have periods of time where a region/hemisphere of a planet is in a rotational winter + wobbly winter at the same time. If the wobble and the rotational period is **not synced, but close** you would experience several rotational winters gradually worsening and then diminishing and then correspondingly the same for summer. The eccentricity and the wobble could be explained by the same planetary impact, hypothetically. Earth has a wobble, but it takes 26000 years to complete and is for most things un-noticeable (though, every some hundred/thousand years people tend to pick different "polar stars" to represent true north) [Answer] **Volcanicity** The OP clarifies *It's not supposed to be a regular but exceptionally long winter that's a part of a recurring cycle of seasons; it's supposed to be a long and unnatural one.* This rules out elliptical orbits because then there wouldn't be "ordinary" short years, and the big winters would be utterly predictable to the extent that all life would have evolved instinctive coping mechanisms. So, it's a Supervolcano on the other side of the globe, that these people do not know about or don't understand the implications of. And for reasons to do with plate tectonics on a different world, it erupts every few centuries (not regularly), rather than every few hundred millennia like Earth's multiple supervolcanoes. When it explodes, dust darkens the sky globally, and an ice age starts, but it doesn't persist after the eruption is over and the dust settles out of the atmosphere allowing the Sun to warm things up again. (Note the "little ice age" here on Earth in C17, possibly caused by a lesser volcano) I wonder what Mons Olympus on Mars was like, back when Mars was habitable? And might such a supervolcano be connected to the evolution of Dragons? [Answer] ### Snowfall The record for yearly snowfall in the United States is was in 1998 when 95ft of snow fell around Mount Baker in Washington between July 1, 1998 and June 30, 1999. Keep in mind that this is a measure of precipitation not the height of snow banks. Strong winds have been known to blow 22 inches of snow into drifts of over 50 ft. Also remember that when people talk about snowfall, especially before modern meteorology, they would talk about what accumulated on the ground and stuck around rather than strict inches of precipitation. ### Ice Winds When it gets cold things freeze. Not much more to say really. Pretty standard winter stuff. ### Years of Darkness This is harder to explain but anything that blocks out the sun for long enough would work. You already have some ideas suggested in your question. Pick any explanation that suits your fancy. Or if you're feeling lazy just say your world is in the midst of a glacial period. [Answer] **[La Niña](https://en.wikipedia.org/wiki/La_Ni%C3%B1a), but bigger** Climate sciences are hard. You can always have a huge ocean, handwave "big ocean, big currents", and have an unpredictible temperature oscillation that does this. [Answer] ## Binary Star System Your planet exists in a binary star system, either orbiting one small star which itself orbits a larger star, [Helliconia](https://en.wikipedia.org/wiki/Helliconia)-style, or orbiting around the barycenter of both stars. In the case of orbiting around one star, you have short, Earth-like seasons based on your orbit around that star, and possibly generations-long hyper-seasons as that star orbits around its parent star. In the Helliconia series, these seasons were marked with a mass die-off of most of the population, while the remaining survivors either packed on fat in order to survive the harsh super-winters, or lost it during the super-summers. (This was caused by a pair of diseases that either killed you or vastly altered your physiology in order to survive the approaching major climate change. In the case of orbiting both stars, your hyper-seasons need not be quite so long, maybe years instead of generations. When the planet is roughly equidistant to both stars, you get a long summer due to being warmed by both stars, but when it's on the far side from one star, you get a long winter since only one star is close enough to provide much energy. You'd have 2 summers and 2 winters per single orbit. With a suitably eccentric elliptical orbit, you could alter the lengths of those such that 1 winter is longer than the other. Also introducing an axial tilt and precession could add more variation to both models, similar to the primary cause of Earth's seasons. [Answer] GOT is a GOAT among fantasy worlds for me. I've imagined how the long winters could have come about many times and never heard or read any single explanation cover it fully. There are constraints to work within though... -GOT is vague as far astronomy but does mention a sun and moon like ours. -Years are measured by path around the sun and constellations. Ancient tales mention a 2nd moon that broke up(?) -Maps appear to only cover the north hemisphere and very little of the south. Imagine a world with a variable star as its sun. A planet with a moon in a newly established (from a geologic/astronomical prospective) tidally locked semi-polar orbit. The inhabitants of northern hemisphere would never see it. Only if they traveled to the polar north or very far south. The southern sea could contain all kinds of weird currents or flora /fauna. When South America broke away from Antarctica, and the circumpolar current started flowing, it threw a MAJOR monkey wrench into earth climate. Imagine a volcanic region that lifts and subsides an area of land allowing a circumpolar flow to be cutoff or established 'randomly'. Also lookup "The Azola Event". Basically duckweed took over the South Atlantic ocean, sequestered billions of tones of CO2 out of the atmosphere in a relative instant and... yeah Monkey wrench. This of course took more than a few years but in an unstable or delicately balanced environment who knows, a chain reaction of smaller synergistic events could add up to a quickly changing system Of course all of this could seem random to the short lived human eye and memory. and could be just a small part of a longer repeating cycle that the inhabitants are too close to see. [Answer] Not strictly an answer, but even on Earth the climate in the past was somewhat different. For example, at some period the Baltic sea was freezing for long enough to build an inn in the middle of it, to serve passing travellers. You can imagine that it had to be combined with much higher snowfall than what we typically experience now (and old nan is most probably referring to accumulated snow, not a single snowfall). The freezing wind is definitely to be expected then (not that the wind itself freezes the bodies of water, it's simply perceived as super cold by humans and that's absolutely enough). I would say the only challenge that remains open is the Sun disappearing for years. The two things that come to my mind is: * changing tilt of the axis, leading to a change what region experiences polar winters. Not exactly causing the described effect (still the polar night will last no more than half of the year) but in the stories of old nannies it can get greatly overestimated * a strong volcanic eruption causing millions of tons of ash to be thrown into the atmosphere, blocking the Sun or at least changing its perception. The Krakatoa eruption actually decreased average temperature of Earth and caused changes to how the Sun was visible Keep in mind GoT involves magic so you may want to use it to amplify effects even you do not want it to be the main cause. [Answer] The best solution is likely to combine several mechanisms, both to tune the desired effect and to achieve the desired unpredictability. The simplest way to make winters longer is to **simply increase the orbital period**. Jupiter has an orbital period of almost 12 years, so at the distance of Jupiter you get cold seasons that last 6 years. To get a more habitable climate, simply increase the strength of the star to compensate for the distance. You might object that a winter still spans half a "year", even though it's longer, but in that case you can just have your inhabitants [measure time in some other way](https://worldbuilding.stackexchange.com/questions/190628/my-planet-has-a-long-period-orbit-how-can-i-make-the-seasons-change-faster-in-o), such that their units translate well to our years. To make seasons more extreme, simply **increase the tilt of the planets axis**. It doesn't have to be by much. This gives a larger proportion of the planet closer to the arctic circle, and winter nights would thus be longer. To make winters more severe relative to the summers, simply **increase the eccentricity of the orbit**. A small increase to perhaps 0.1 or 0.2 would have a very noticeable effect on the seasons. To make seasons more irregular, *add some other very large planets to the solar system*\*. Possibly inside the orbit of our planet of interest. This will cause small perturbations to the orbit Now for the fun part: **Combine these effects**! There are many possible configurations. If the direction of the axial tilt aligns with the major axis of the elliptical orbit there will be one pole with mild winters and one with severe winters. If they are perpendicular one side will have dark seasons that are colder towards the end, while the other has dark seasons that grow progressively warmer. In any case, the relationship between the direction of the axial tilt and the major axis of the orbit will likely drift due to interactions wit your heavy planet (or better: planets!). This leaves open the possibility of legends of back when things where *way* worse than they are nowadays! Check out the [Wikipedia page on orbital resonance](https://en.wikipedia.org/wiki/Orbital_resonance) for hints about periodical interactions! [Answer] Short Answer: I think that my rough calculations show that it might be possible to design a system where there are two co-orbital planets with very similar orbits, and where every few decades the outer planet suffers an eclipse from the inner planet lasting for at least one who year of hte outer planet. Long Answer: I once read that George R.R. Martin did write that there was an explanation for the suuper long winters and it would be given sometime in th future. I also hear it is taking him a long time to write the latest books in the series, and I suspect there is no guarantee that the explanation will be given before the last paragraph in the last book. And maybe not even then. And I wonder whether George R.R. Martin aleady knew the explanation when he wrote that there was one, or if he is just stalling for time until he can think of one which will be good enough for him and for his fans! I don't know whether Martin will use a scientific and astronomical explanation for the long and bad winters or some sort of magical explanation. But I have an idea for a scientific and astronomical explanation. The planet in ASOIAF, and any similar planet that KEY\_ABRADE might be thinking of writing about in a series of their own, apparently has a fairly normal cycle of seasons. At least the people there know of years, since the winter is said to last for years. I believe that in ASOIAF people's ages are given in years, and ages inASOIAF years seem to corerespond fairly well with the number of Earth years those characters seem to have lived. Possibly there is a study somewhere about the possible range of ASOIAF year lengths compared to Earth year lengths. If so, that would be very helpful. For now I will assume that ASOIAF years are approximately the same length as Earth years. I haven't read the books or seen the series, so I don't know if the world in ASOIAF does have a normal cycle of spring, summer, autumn, winter, and spring again, with occasional super winters which last for several years. Not being familiar with the story I can't say for certain whether the planet does have normal seasons, including normal winters, betweent he terrible long winters that last for years. A world with little or no axial tilt - <https://en.wikipedia.org/wiki/Axial_tilt> - would have very mild seasons which people might not notice much. In temperate zones the cycle of the seasons is very important, and people notice it, and that is the main evidence for the length of a a year. But on Earth, people lived in tropical regions which the seasons were often much less important. Some tropical places have important and noticeable wet and dry seasons, but maybe some do not. So in some tropical regions people might not have noticed any vary important cycle of the years to show them how long a year is. Do those tropical cultures use years in their native calendars? People can notice the length of a year without having a noticeable cycle of seasons. A midnight the stars on the line between due north and due south through the zenith will be in the opposite direction from the direction to the Sun. Over the course of a year, the celestrial sphere will seem to rotate, though actually the line between noon on Earth and midnight on Earth will be doing the rotating. After six months the stars seen on the midnight line will be 180 degrees, halfway across the sky, from the stars that were seen there six months earlier. And after another six months the original set of stars will be seen on the midnight line in the sky. So that is one way which people could use to figure out the approximate length of a year. Ancient Babylonian astronomers and astrologers were able to plot the postion of the Sun against the background of the stars despite not mbeing able to see the stars in the daytime sky. They knew the Sun at noon would be almost exactly opposite to the stars on the midnight line on the previous and following midnights. So ithey wound it i aeasy to plot the suns's position against eh unseen stars whose positions "on" the celstial sphere had long been mapped. So it is possible that people know the length of a year, regardless of how noticeable the regular and ordinary seasons are on the ASOIAF planet. My theory is that possibly the ASOIAF planet could sometimes be eclipsed for years by a planet in an interior orbit around their star. The gravitational interactions between and star and its planets create forbidden zones around each planet. If an astronomical body enters the forbidden zone of a planet its orbit will be gradually perturbed until it takes a new orbit outside the forbidden zone, or crash into the star or antoher planet, or is ejected from the star system. Such things are believed to have happened more than once during the first few hundred million years of the solar system, ecjecting or colliding many asteroids, comets, planetesimals, moons, and even planets. So the forbidden zones between neighboring planets make it hard to squeeze planetary orbits close enough for one planet to clipse all of another planet, or even any part of the other planet. But there are theoreticall and real examples of astronomical bodies which share the same orbit, called a co-orbital configuration. For example, there could be two planets in trojan orbit around their star, one planetbeig about 60 degrees ahead or behind the other planet in their mutual orbit around the star. But a trojan planet wouldn't cast a shadow on its co-orbital planet. Saturn has examples of moons in Trojan orbits with other moons, which are no good for this question, and it has anotherand more interesting set of co-orbital moons. Epimetheus has dimensions of about 129.8 kilometers by 114 kilometers by 106.2 kilometers and its orbit around Saturn has a semi-major axis of about 151,410 kilometers. Janus has dimensions of about 203 kilometers by 185 kilometers by 152.6 kilometers and its orbit around Saturn has a semi-major axis of about 151,460 kilometers. Note that the difference between their orbits is less than their sizes. That seems like a recipe for a collision, even though they have existed in a co-orbital configuration for thousands, millions, or billions of years. If perfectly circular, the orbit of Epimetheus would have a circumference of about 951,336.28 kilometeers, and the orbit of Janus would have a circumf951,650.44 kilometers. Epimetheus has an orbital period, during which it travels 360 degrees around Saturn, of about 0.694333517 Earth days, while Janus has an orbital period of about 0.694660342 Earth days. Epimethmeus travels about 518.4828201 degreees along its orbit every Earth day, while Janus travels about 518.2388834 degrees along its orbit every Earth day. So Epimetheus gets about 0.2439376 degrees ahead of Janus every Earth day. So after 1,475.78251 Earth days, or about 4.040485285 Earth years Epimetheus gets a full circle ahead of Janus and so catches up with Janus from behind. So Epimetheus should have smashed into Janus after no more than four years of sharing an orbit. > > Epimetheus's orbit is co-orbital with that of Janus. Janus's mean orbital radius from Saturn is, as of 2006 (as shown by green color in the adjacent picture), 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 more massive than Epimetheus. The exchange takes place close to every four years; the last close approaches occurred in January 2006,[14] 2010, 2014 and 2018. This is the only such orbital configuration of moons known in the Solar System[15] (although, 3753 Cruithne is an asteroid which is co-orbital with Earth) > > > <https://en.wikipedia.org/wiki/Epimetheus_(moon)#Orbit> So could an Earth like planet and another planet be co-orbital like Epimethmeus and Janus? If the inner planet was moving 0.2439379 of a degree farther than the other planet every Earth day, it would travel about 89.098317 degreees past the outer planet in one Julian calendar year of 365.25 days. If the outer planet has an orbital period of about one Earth year, or about 365.25 Earth days, and orbits its star at at a distance of 1 AU like the Earth does, its orbit shoudl have a circumferance of about 939,950,349.2 kilometers, and each degree of arc along its orbit would be about 2,610,973.192 kilometers, and a planet 89.098317 degrees wid would be about 232,633,317.2 kilometers in diameter. That would be too big to fit inside the orbit of the Earth. It would also be about 1,626.988 times the the 142,984 kilometer equatorial radius of Jupiter, and planets and brown dwarfs can not get much larger in diameter than jupiter. Adding more mass just makes them denser, not wider. So let me design an extreme example of co-orbital planets that almost touch. Earth has a radius of about 6,400 kilometers and thus a diameter of about 12,800 kilometers. Suppose there is a planet of that size in Earth's orbit, and another planet in an almost identical orbit which is about 20,000 kilometers smaller than Earth's orbit. Earth has a semi-major axis of about 149,598,023 kilometers, so if its orbit was perfectly circular the orbit would have a circumference of 939,951,306.2 kilometers. Earth has an average orbital speed of about 29.78 kilometers per second. So it would take Earth about 31,563,173.48 seconds to complete one orbit. The sidereal year of Earth, the time it takes to complete one orbit as seen from the distant stars, is 31,558,149.504 seconds, the difference being explained by Earth's elliptical orbit and varying orbital speeds. So the orbit of the inner planet in my example would have a semi-major axis of about 149,578,023 kilometers and thus if it was perfectl circular it would have a circumference of 939,825,642.6 kilometers. It would have a slightly faster orbital speed than Earth, but I will make it about 29.78 kilometers per second, just like Earth's. So the inner planet would take about 31,558,953.75 seconds for each orbit. One degree of Earth's orit would be 2,610,975.851 kilometers, and one degree of the inner planet's orbit would be 2,610,626.785 kilometers. One arc minute of Earth's orbit would be 43,516.26418 kilometers, and one arc minute of the inner planet's orbit would be 42,510.44642 kilometers. One arc second of Earth's orbit would be 725.2710696 kilometers, and one arc second of the inner planet's orbit would be 725.1741069 kilometers. So Earth would travel 2,572,992 kilometers in 86,400 seconds or one day. That would be 59.12713438 arc minutes per day. And the inner planet would also travel 2,572,992 kilometers in 86,400 seconds or one day. That would be 60.52611103 arc minutes or 1.008768517 degrees per day. So the inner planet would go 1.39897665 arc minutes farther than the outer planet each Earth day. Since there are 21,600 arc minutes in a full circle it would take 15,439.85741 Earth days or about 42.2720 years for the inner planet to gain a full circle on the outer planet. The inner planet would have an angular diameter of about 27.74 degrees or 1,664.50416 arc minutes as seen from the outer planet. If the star has an angular diameter of about 0.5 degrees or about 30 arc minutes, the planet will travel a total of about 55.98 degrees or about 3,359.00832 arc minutes from first contact to last contact during its eclipse of the star. If the inner planet gains 1.39897665 arc minutes on the outer planet each Earth day, the inner planet will take 2,401.046737 Earth days or 6.5737 Earth years for the eclipse of the star. And according to my rough calculations about 3,299.00832 of those arc minutes will be during a total eclipse of the star, with all of the star covered, which should take about 2,358.158244 Earth days or about 6.4562 Earth years. So that imaginary outer planet should spend about one seventh of its time in eclipse. Except that during what would otherwise be the middle of the eclipse, the two palnets will be at their closest and will switch orbits, thus putting the former outer planet into the inner orbit and into the bright sunlight. But then, 42 years later, when the former outer planet is eclipsing the former inner planet, they will switch places again and the former outer planet will be the outer planet again and will be eclipsed again. So each planet should experience about 3 years of eclipse every 42 years, one fourteenth of the time. I note that: > > In addition to swapping semi-major axes like Saturn's moons Epimetheus and Janus, another possibility is to share the same axis, but swap eccentricities instead.[11] > > > <https://en.wikipedia.org/wiki/Co-orbital_configuration#Exchange_orbits> I am not certain how that would work or whether that would allow one planet to always be in the outer orbit. I note that this is a very extreme example of two co-orbital planets being very close together. If the fictional Earth like planet is supposed to have a moon in an orbital period about the same as Earth's, that orbit would be many times as wide as the distance between the planet's orbits. For a planet to have a moon at the distance of Earth's Moon with a stable orbit, the inner planet would probably have to be at least 1,000,000 kilometers closer to the star. If the inner planet's orbit gets too much smaller than that of the outer palnet, they may cease to be co-orbital. And then they would have separate forbidden zones, and they would have to get much farther apart to be out of each other's forbidden zones. Another possibility would be to make the inner planet a bit closer to the star, and make it a giant planet with a ring system. All four giant planets in the solar system have ring systems, though only Saturn has spectacular and easily seen rings. Jupiter has an equatorial diameter of 142,984 kilometers. And no giant planet can have a diameter more than about 20 percent larger than Jupiter's, so no more than about 171,580 kilometers. Saturn is much smaller than Jupiter, but has a large ring system. The A ring, the outermost bright ring, has a radius of 136,775 kilometers and thus a diameter of 273.550 kilometers, and there are fainter rings much farther out than that. Suppose that the inner planet has a ring system with a diameter of about 2,700,000 kilometers, about 10 times that of Saturn. Suppose that it orbits around the star 5,400,000 kilometers closer to the star than the outer planet, and thus at a semi-major axis of 144,198,023 kilometers, and an orbital circumference, if the orbit was perfectly circular, of about 906,022,134.2 kilometers. The inner planet with the rings would have an orbital period of about 0.946185 Earth year or about 345.59407 Earth days according to this orbital calculator. <https://www.calctool.org/CALC/phys/astronomy/planet_orbit> So the inner planet would travel about 1.0416845 degrees along its orbit during one Earth day, while the outer planet in the position of Earth would travel about 0.9856262 degree during one Earth day. So the inner planet would gain 0.0560583 degree on the outer planet during one Earth day, and it would take it 6,421.8857 Earth days or about 17.582164 Earth years to gain 360 degrees on the outer planet. When the inner planet with the ring system passes closest the ring system will have an angular diameter of about 22.918332 degrees as seen from the outer planet. With the star having an angular diameter of about 0.5 degree, the ringed planet will travel a total angle of 46.336664 degrees during the eclipse. That will take it about 826.57989 Earth days or about 2.263 Earth years. So I think that thes rough calculations show that it might be possible to design a system where there are two co-orbital planets with very similar orbits, and where every few decades the outer planet suffers and eclipse from the inner planet lasting for at leas tone who year of hte outer planet. Of course it would take more expert calculations than mine to work out the details fo such a system and make certain it was possible. [Answer] **Trinary Star System** The long-term evolution of a system of three roughly-equal masses is exceedingly hard to predict because the system exhibits chaos for most initial conditions. The same is true of a smaller mass caught between the three larger masses (i.e. a planet among three stars.) We have found (mathematically) a few known stable orbits in trinary systems, but for most initial conditions, we simply don't know what will happen in the long term. They could result in ejection, they could be periodic, but the period might be millions of years. This means a fictional work has broad license to make up weird orbits, which could exist, for all we know. (Especially for all a human reader, who is not a supercomputer, knows.) For example, a planet could be in what appears to be a stable-ish orbit in the habitable zone for centuries, then take an excursion a little further away for a few decades, which could explain these sorts of long, unpredictable mega-winters that are survivable with effort. (You don't need a celestial object to eclipse the suns, heavy clouds induced by the sudden climate change suffice.) This features prominently in Cixin Liu's *The Three-Body Problem*, which at one point describes a planet which is sometimes thrown so far away from its three suns that the atmosphere freezes, only to come back to a habitable orbit later. [Answer] I don't have a complete solution but how about a frameshift: The planet is orbiting a star that's too cool, Winter is the normal state for the planet. However, the star is part of a multi-star system. The other "star" is a black hole, the deadly polar jets are pointed far from the planet so it doesn't fry. This object has it's own companions, red dwarfs or brown dwarfs. They shed too little energy to be meaningful for warming the planet. However, they are all in elliptic orbits about the black hole and pass close enough that substantial amounts of gas get ripped off at periapsis. This gas feeds an accretion disk that sheds enough energy to keep the planet reasonable. Each time a companion passes the disk glows more (summer), then as it's digested it fades (winter). However, there's a time when there's no object coming by for a while, now you have Winter. [Answer] Out of universe, I strongly suspect that GRRM simply slightly misunderstood the relationship between axial precession and Earth's seasons, and so came up with a fantasy high concept of a planet where the planet could have an irregular or long-period "wobble" that occasionally put the northern hemisphere into winter for an extended period of time. It is very common for people - even educated people - to incorrectly believe that winter is the result of a change in axial tilt, and not the effect of revolution around a star for a planet with a constant tilt. I think GRRM's explicit statement that traditional physics has nothing to do with the phenomenon is a post-hoc rationalization of a simple error that would never have been an issue if the series didn't explode in popularity. [Answer] It's possible that Nan's statement is part hyperbole and part myth. Not all of it is to be taken literally. It could be that the "long night" isn't decades, but so bad that many children are born and die fairly quickly because of harsh conditions. There could be negative bias involved. This is where you tend to remember the bad things more than good things. This is probably because negative information seems to require more processing than positive. It could be a volcano on an unexplored part of the world that erupts every so often(every 200 years, maybe) and if you could combine the hyperbole with this, it might seem to take longer than it actually does. It also could just be "magical" in nature. Maybe there is some, unknown to the world, magical artifact that absorbs energy for a number of years, decades, or centuries and once it's "full"(or empty) releases a "pulse" of hand-wavium that puts the planet into a "freezing" state and also releases(multiplies, whatever) the evil that "comes howling from the North." [Answer] It is quite probable that Old Nan is telling a made-up story there, or greatly exaggerating actual events. 100ft/30m of snow "in one go" would kill about everyone, like an avalanche (chance of survival: less than 10% after 2 hours, assuming that you don't asphyxiate right away). Note that the Red Keep is plausibly tall enough to provide a supply of air to its inhabitants even with 100ft of snow around. That said, an avalanche or winds (see sphennings's answer) can cause localized snow pileups. But in reality... ## It needs to be pretty hot (!) Snowfall is a form of precipitation, so, obviously, the air needs to be quite humid. If the whole planet is below freezing temperature, there will be no supply of water vapor (unless there are significant numbers of improbably strong geysers). Once the air is dry, no further snow will fall. So some very elliptic planetary orbit or variable star activity or world-wide shadowing won't plausibly give us 100ft/30m of snow. So we need hot regions where water evaporates to supply cold regions with snow. Note that polar regions, despite being pretty cold, do not receive as much snow as other regions (IIRC, the Artic receives 0.2m per year, while Alaska and Greenland can go up to 2.0m/yr). Now, an obvious "solution" to that issue would be a tidally locked planet (tidally locked to the sun, obviously). One half is frigging hot, the other half is darn cold. There will be an intermediate region where life would be possible. However, a planet doesn't get tidally locked and "tidally unlocked" at the convenience of some story which needs to be told. A tidal lock is there to stay. Of course, there's libration, which means that the planet might "wiggle a bit around" so the intermediate regions vary a tiny bit. But the biggest issue is that a tidal lock prevents day and night cycles. Viewed from the planet's surface, the sun would always be in the same spot. So my assumption is that Old Nan is making things more interesting by a bit of exaggeration. 100ft/30m of snow have been observed for a complete winter season on Earth, just not "in one go", and we know of Dark Years. After all, Bran explicitly requested a horror story from her. [Answer] Just as a regular winter occurs. The continent that Game of Thrones takes place on might be close to one of the poles, and the planet might be tilted like ours (or more). If the planet orbited its star more slowly than the earth does, this would cause normal winters that were much longer than ours. Neptune's years are 165 earth years long, allowing for seasons that take place over generations, and midwinter nights years long close to the poles. ]
[Question] [ I have a world where the average lifespan of 90% of the population is 120-150 years old and history is almost solely maintained in writing (so there are not really many visual recordings of past events). Learning history is not particularly important for the vast majority of people either and there is no uniform way history is taught to children (if it's taught at all), only an elite few really study and/or maintain historical records. However, some of these elite few, the spiritual leaders of the world, do share history and historical lessons to the masses. Given these parameters, is it safe to assume that a specific event happening around 1000 years ago could be considered "legend" or "lore" in the sense that even though people may be familiar with the story, the details are fuzzy and some don't even really think it happened (or perhaps think it's just a parable)? I guess this would partially depend on the scope of the event, so let's say that it's a worldwide natural disaster, a flood that reshaped the continents in a matter of 2 days. 1000 years later, people know of the story of the flood and that's how the continents came to be how they are now because it's told by the spiritual leaders... but most people don't really believe that a 2 day worldwide flood really happened, as that seems impossible. Surely it's a parable or an exaggeration of what really happened. Hopefully that example helps. Edit: A couple of the answers made me realize that giving information on birth rates in this fictious place would help with answering the question. To answer this: People in this world tend to have children between the age of 30 and 50, mostly because women can strictly control when they conceive and men can control the gender, given this, there's no accidental births (or it's really rare) and so people tend to only have children when they've settled down and know they can take care of them (afford it) and don't tend to have that many children in general (although exceptions exist of course). [Answer] ## Yes, depending on the circumstances The actual number that's important here is not lifespan, but rather the time period for a generation. Legends only happen with the retelling of information from one generation to another, thus the story goes from "Great King" to "Amazing King My Dad Told Me About Who's Much Better Than This One" to "Awesome King My Dad Told Me His Dad Told Him About Who Would Never Have Lost To Whoever Conquered Us" to "We Culturally Appropriated This King That All The Peasants Won't Shut Up About And He's Ours Now". You see? It has to do with the transfer of information. The time period for a generation is given to be 25 years. In your species, it might be higher - or not, depending on the physiology. If the women have the same fertility period as humans, it will be the same, despite the advanced lifespan. If they can still have children well into, say, their 70s, then the generation will increase, perhaps to 45. If they don't start being capable of childbirth until, say, 40, than the generation significantly increases - maybe to 60. Now, take whatever number you end up with and divided the 1000 by that. That gives you the number of generations. Next, there's one other factor - the transfer of information. Legends happen when information is loosely transferred (i.e. through song, play) rather than strictly transferred (i.e. 4k video saved onto multiple hard drives). So, if you have a sufficient number of generations, a loose method for telling stories over prone to exaggeration, and/or a highly superstitious population that believes in demigods, you have a simple siege turn into an epic of legendary proportions in a mere 800 years! (Trojan War: 1300 BCE. *Illiad* and *Odyssey*: 500 BCE) [Answer] The 'mythologizing' of people and events is less a function of time than of the loss of information. People and events become mythological when two things happen: * Small humanizing details are lost to memory. Things like specific facial features, mannerisms, hair color are forgotten; accounts of idle conversations, minor activities, and everyday life events are dropped as lacking meaning. * Specific 'important' qualities are magnified, reified, or even replaced with idealized conceptions. Thus a person might be conveyed as excessively beautiful, strong, or austere; an event might be described with grandiose or mystical terms. The process of mythologizing means replacing real-world things with archetypal representations. It's a bit like that old-time movie technique of smearing vaseline on the camera lens: small flaws and peculiarities are obscured, and the people being filmed take on a glossy, etherial glow. In regions with low literacy and largely oral transmission of information, mythologizing can occur quite quickly. Both Christ and Buddha took on mythological characteristics within two or three hundred years of their lives. In more technological, literate eras the process of creating a myth becomes far more difficult, because too many of the all-too-human details of a given person can be culturally retained. There are structured efforts to create myths in the modern world — that's the essence of propaganda, which strictly controls available information to paint a person, thing, or event in a glowingly flattering light — but as often as not that effort ends up in demonization. For the obvious example, Hitler tried to coerce the world into viewing him as an archetype of the perfect race and ended up as an archetype of pure evil. But in any case, a thousand years is more than enough time to create a mythology, assuming relatively low technology and literacy. The Arthurian legends coalesced in a time-scale that was only slightly longer than that. [Answer] I say no on any meaningful scale, let me tell you why. I hope you don't mind I will use rulers in place of events, as the book keeping is bit more consistent, but I think it would apply to events as well. The first historical ruler of Bohemia was Bořivoj (about 852-890 A.D.) the first. He is a historical figure, with several period texts mentioning him. His father on the other hand is legendary, not because he accomplished great deeds, but because frankly we are not certain who it was. Often a name Hostivit(?-870?) appears, but it is mentioned by one chronicler who combined legends with history, and some frescas, which include other legendary characters. From this example 1,152 years was enough for someone to pass into legends. On the other hand if we look to ancient Mecedonia (Alexander the Great lineage), we can get to Amyntas the first of Macedon who ruled between 547 – 512 / 511 BC. Herodotus names five other kings who came before him, but there are no other historical references[[1](https://books.google.cz/books?id=lNV6-HsUppsC&pg=PA229&redir_esc=y#v=onepage&q&f=false)] to them, are by all accounts they are legendary. Sooo thats 2569 years for someone to become a legend. Then again if we look in the direction Who is the oldest historically confirmed ruler? Apparently there is some debate, but since here we at least know name I will write > > Me (or Ishib)-baragesi of Kish, Akka-Inannaka of Umma and a certain > HAR.TU (exact pronunciation unknown) of the city of PA.GAR (modern > Tell Agrab). They probably ruled around 2700-2600 B.C.E."[[2](https://science.howstuffworks.com/environmental/earth/archaeology/first-king.htm)] > > > To me this implies that all rulers we know about and came before them are by definition legendary. I say this gives us an upper bound of 4722 year for someone to be legend. But what is the lower bound? I honestly cannot find a definite answer. Both Poland and Denmark seems to place the last semi historical ruler somewhere around 900AD and since this coincides with Christianization an proper record keeping. This would put our lower bound at 1122 let. We could cheat a little and say that since we know next to nothing about Aztecs prior to about 1400 we could argue for 622 years, but here we are cheating a bit and it doesnt matter anyway. If we say that the life expectancy of your people is 2-3times higher then ours, and a rate of legendification to stay the same. Then we would expect the earliest legends to occur sometime around 1244 - 1866 years back, but rally more like 2000 - 3000 year back. This really got away from me, I will stop now [Answer] It can be as short as 200 years with no issue. Take, for example, John Henry and Paul Bunyan. Their time-frame goes back to the late 1800s, but the tales of their feats are absolutely considered legend. Once the adults who were present have died, unless there is excellent recording of a person's life, as with the founding fathers, or with leaders like presidents or kings, their stories can be handed down and distorted fairly quickly to aggrandize their feats. [Answer] There are people today who think that the Moon landings did not happen, despite overwhelming evidence that they did. So the standard "some people" is problematic. In one part of my family tree, I can reliably trace four generations. For the fifth generation, there is the name and date of birth, but other details are fuzzy. Another part of my family tree can be traced back well into the 16th century. The key to that were low-level "spiritual leaders" -- Lutheran pastors in the family tree who recorded not just the bare minimum dates (baptisms, weddings, burials) in the church books, but added additional detail on their family that helped to navigate musty records. My family tree is important to me, but not on the global scale. So this provides a **lower bound** on the ability of a literate society to preserve **minor** details. So it would be a culture clash between those who believe something to be historical fact, and those who consider it myth. [Answer] **Curiously, I just used the following example in another answer** What's a legend? Rod Serling, famous for the introduction to the old TV show "The Twilight Zone," is known around the world for saying the words, "Imagine, if you will..." Just one problem, *he never said it.* And the last episode of that original series aired in 1964, just 57 years ago — a far cry from your 1,000 year limit. As several have said already, legends occur because information is lost — *or not checked frequently enough to keep the perception of history pure.* Robin Hood... King Arthur... George Washington cutting down a cherry tree and uttering the words, "I cannot tell a lie..." It's not that hard for something true to be misrepresented or false to be propagated. So, can you do it with a 1,000 year block? # Yes All you need is for the living memory of the event to be spread too thin in the population. After that, the youngsters will begin telling those who witnessed the event that they don't know what they're talking about because the popular perception has more believers than those who know the truth. [Answer] Myths and Legends can be created in real time even in the modern world where the internet allows factual video evidence of events to be available to anyone. For real world examples you can look at holocaust denial, moon landing conspiracies or even flat earth, biblical creationism. Depending on who you ask you will get two very different stories about Kyle Rittenhouse, even though there was videos of the events in Kenosha uploaded in real time as people are often too lazy to find the evidence and will just repeat what they were told about an event If enough people, and particularly those responsible for teaching children, decide that they like an alternative version of the facts then that will become the default truth and the real facts will be relegated to historians futilely telling people that they are wrong [Answer] A legend is > > a non historical or unverifiable story handed down by tradition from > earlier times and popularly accepted as historical ([Dictionary.com](https://www.dictionary.com/browse/legend)). > > > or > > very old and popular story that may be true ([Collins](https://www.collinsdictionary.com/dictionary/english/legend)) > > > or > > a very old story or set of stories from ancient times, or the stories, > not always true, that people tell about a famous event or person > ([Cambridge](https://dictionary.cambridge.org/dictionary/english/legend)). > > > So any historical story or event that is very **POPULAR** amongst the people (may be true or false) can be called a legend. [Answer] It entirely depends on the attitude of the people toward history. In early modern times, there are records of people calling things ancient *that had happened in living memory*. Now, that you have writing indicates that they are not going to come up against the limit of about 150 years for accurate oral transmission. But if studying history is not big, there is going to be a lot of vagueness in their knowledge except for practicing historians. [Answer] In a society that was, and remained, broadly literate, and with temporally progressive worldview (i.e. having a concept of events proceeding from one to the next in an orderly fashion), through the event no, they'll have written records and a fixed date for the event; it will be a matter of History. For an event to become legend or myth you need a break in hard copy records, a period of oral history where the record of the past becomes what peoples grandparents told them *their* grandparents told them while sitting around the fire at night. Those stories start as memories of what happened not a concrete record of the event, then they change a little at each retelling. After a couple of generations they stop being recollections and become folktales a little later they become legends and then as S.M. Stirling put it "some smart arse with an axe to grind "proves" it never happened at all". [Answer] Is that timeframe long enough? As others have shown, yes - it's feasible, even probable with the right conditions. However as a counterfactual, consider the oral history of indigenous Australians (link: [The Oldest True Stories in the World](https://www.sapiens.org/language/oral-tradition/)), successfully identifying landforms all around the continent which were submerged at the end of the last ice age over 7,000 years ago. This sort of achievement most likely requires the civilisation to be illiterate as written works are less able to keep up with changing language use and are more fragile (at least prior to mass media and printing presses). [Answer] **Yes**, though that is significantly longer then required I give you John Fitzgerald Kennedy (JFK). Who is he? Why one of America's most beloved presidents, whose loss we all regret. While he was alive, the white house was like... a royal court, Chamelot! and he, its king. He was faithful and true to lovely wife/Queen Jacqueline. His death ushered in the 'post heroic' era in America and set us on the path to division, tearing at the fabric of our democracy. There are people alive who knew John F. Kennedy personally who believe the legends/myths surrounding the man. Or perpetuate it to further their own agenda... Either way the JFK of america's imagination, and the JFK that really lived were very different people. **You don't even have to be dead** Just look at anyone with a cult of personality... Donald Trump for example. Is half of what his supporters believe about him true? Nope, he is not the savior, he does not excrete gold, and he is not as smart as he thinks he is... What about his detractors?... again, a lot of what they say about him is also wrong, or greatly exagerated, he is not the devil given human form. ]
[Question] [ What could cause a culture to change their writing style from left to right similar to English to vertically like traditional Chinese? Example: [![An example of Chinese traditional writing](https://i.stack.imgur.com/WYMzm.png)](https://i.stack.imgur.com/WYMzm.png) [Answer] # Authority say-so Usually it happens because the authority / authorities in charge of these matters decides it to be so. [Hangul](https://en.wikipedia.org/wiki/Hangul) would be a prime example of this. And when Korea was occupied in the 1910's, Japanese was made the official language, another example of authority say-so. [Answer] It might be easier to use a different format in a particular technology or the other language is used for trade. Trade languages can spread and there can be a simpler way to write things down, which can then spread as an idea--which will then have to taught to others. This means that whoever controls knowledge and learning will have the power to do this. My example is the switch from [Roman Numerals to Arabic.](https://web.archive.org/web/20171209204114/http://mathforum.org/library/drmath/view/52545.html) In this case the change took hundreds of years. It was introduced in round about the 900s (earlier in some places, but for all practical purposes...900s) and monks that were into math thought it was really neat--plus it took up less room in their ledgers. They wrote to each other and it became a fad, however, for the common folk and most people, it was difficult. Roman numerals follow the pattern of the abacus, which is what most folks used for math--each symbol representing a unit of a certain number. Arabic was thought to be confusing enough (after all, a decimal point or a missing place could change the value entirely) and was even outlawed in the 12 & 13th centuries in some places. The system was already available and part of the culture when the printing press was invented. This is where tech comes in. Roman numbers were much longer, and Arabic was much easier to use with movable type. One of the complaints about the Arabic system was the similarity between the form of numbers, which, when people were writing them down, led to misunderstandings. The standardized print helped with that, and spread the format more consistently. This is old tech, but my point is that if a language is more compatible with the available tech, an earlier form may be abandoned by and large because of it. It took a very long time for this conversion to happen with numbers,but the world is faster paced today, particularly when it [comes to language changes](https://www.theguardian.com/science/2015/may/01/icymi-english-language-is-changing-faster-than-ever-says-expert). The way I can see it happening is this: a small country gets free tech from a country with a different language system. It's not easily compatible with their language as written, so people figure out a different way to use it. It might be a poor country that didn't have much of an education system in the first place, and they want to take advantage of what they have, but maybe they don't have many computer programmers--and those they have aren't interested in converting all the computers or writing a program to accommodate their language. Instead, it's just easier to adjust how it's written. Now, that's just an example of how that could work--there's lots of other ways you could do it--even by ramping the tech back. The formula is thus: 1. Another system of language or way of thinking is available 2. The new tech or lack of tech or shift in writing tech makes the current/old system more difficult to use than the other style. 3. People begin using the new tech and teaching the new system of language. [Answer] # Practicality Slow changes and **authority say-so**. An example would be the Japanese system: * Kanji system was copied from China. * Hiragana was created by aristocrat women to communicate with each other. The system evolved with small changes. There were many variants of a syllable, until authority say-so that there shall be only one. * Katakana was created by men and used in official documents, somewhat an authority say-so. All this mess has been cleaned to the modern format by multiple authority say-so, **often ratifying the most common practice at the time**. That bold part is really important because the change often goes to multiple directions and the authority say-so is a way to keep it together. It would be really hard for English to become vertical because the letters have evolved to such that they are best red horizontally. The verticality of Chinese is because the ink and sleeves are not compatible. **The idea for a real-life case:** The change would probably be in a language or an adoption of a completely new writing system. Horizontality is wide-spread and the current technology creates a lock-in for it. The best realistic reason I can invent for the change to occur is that machines get their own writing system. Not all robots have a printing machine, so the system is to be such that it is easy and fast for them. The change would probably be also in the language. People would then adopt this system by using the both systems in parallel, but slowly use less and less the old system, so that at some point the new system has replaced the old one. [Answer] ## Religion say-so Basically variant of [MichaelK answer](https://worldbuilding.stackexchange.com/a/71184/2071): Religion requires you to change your writing style and *everyone* follows such religion. Example: Switch in [Great Moravia](https://en.wikipedia.org/wiki/Great_Moravia) from [Cyrilic](https://en.wikipedia.org/wiki/Cyrillic_script) to latin alphabet ## It is easier to do so Newly introduced script is easy to understand by people using current style of writing. Example: Jan Hus and [his change to Czech Alphabet](https://en.wikipedia.org/wiki/Orthographia_bohemica) [Answer] Why did Chinese do just exactly the opposite? [As I recall](https://en.wikipedia.org/wiki/Horizontal_and_vertical_writing_in_East_Asian_scripts#Chinese), a major scientific journal published that it would do so, not for the sake of being different, but to better handle the inclusion of math formulas and tables. > > The earliest widely known Chinese publication using horizontal alignment was the magazine Science (科學). Its first issue in January 1915 explained the (then) unusual format: > > > 本雜誌印法，旁行上左，並用西文句讀點之，以便插寫算術及物理化學諸程式，非故好新奇，讀者諒之。 > > > This magazine is printed so that it goes sideways from the top left, and is marked with Western punctuation. This is to make the insertion of mathematical, physical and chemical formulae convenient, not for the sake of novelty-hunting. We ask our readers to excuse us. > > > So, more generally, the new layout is better for the medium or better able to handle complex mixed content. [Answer] ### Who would do that? Languages evolve indeed, but that kind of change requires a willful reform. The only way to have that change into people's habit is to have the state enforce it. Logistically (assuming there is no popular opposition), doing it is pretty straightforward: change the school, change the official papers. Providing the rest of society follows, it will be considered perfectly normal in a matter of decades. ### How? The main problem is of course to get the private text providers to follow. Depending on your government: * **Democracy**: If the decision was popular in the first place, companies will follow the trend. * **Dictatorship**: Just make it mandatory. * **In between**: Give more subsides/less taxes to providers of the new system. ### Why? Now why would a ruler/ruling class/society want to do that? A despotic ruler may want to complicate life for the elderly. That's not the best way to do it, but it may come with other bothering rules. If under control by Chinese (or other vertical-writer) authority, the government may have to adopt the ruler's language. The original language may survive through the occupation. But once the occupant is gone and there's a country to rebuild with little money... changing the layout of everything is costly. If everybody is now used to Chinese layout, and we get back to the former writing, we can all be happy! A new service that uses some vertical writing starts being used by everyone. The vertical features becomes popular and is also more adapted to smartphones. This sounds dumb but smaller features have already changed our language [#chirper](https://twitter.com/). [Answer] Educational standards as set by the government or government-related bodies. Assume a free country where people can mostly write as they like. If public schools (and any private schools which are considered equivalent) adopt a single, unified system *for grading purposes*, after a few years any other system will appear uneducated, or possibly just old-fashioned. Either way, parents who want their children to do well in school will adapt the new system. [Answer] ## Tools. Look at us. 50 years ago, everybody was writing in cursive with pens. 30 years ago everybody was using a typewriter with its fixed-width characters. 10 years ago everybody was using computers and word processors. Nowadays everybody is typing emojis in their phones. Our own writing system is being (re)defined by the tools we use to write. Of particular interest are the [typesetting and linotype technologies](https://en.wikipedia.org/wiki/Typesetting). See also how technological artefacts such as fixed-width character matrices made writing systems to adapt to them in weird forms such as [double-width characters](https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms). So cursive versus fixed-width characters are not as radical a change as horizontal-to-vertical, but it's plausible that your culture has a typesetting technology, or material, which can only handle verticality. Maybe there is an influx of foreign machine vertical typesetters. Maybe the paper-like material works better / survives longer when placed vertically. Whatever the reason, the practicality/cost of using the new tech can take over a pre-existing writing system, even at the cost of changing it. [Answer] **Ideology/politics** Before WWII Gothic Fraktur was one of most popular typefaces in Germany and all around the Europe. But after Hitler adopted it for his ideology and then lost the WWII it was widely abandoned as part of anti-hitler ideology. And it happened mostly organically – it had disappeared even in countries where there were no law forbidding it as people started perceiving it as a "nazi" typeface, while previously it was just one of historical ones originating from medieval calligraphy. Other example: shifts between Cyrillic and Latin scripts in slavic languages. It was often connected with religious and national identity, with cyrillic being connected with pro-russian politics and orthodox church and latin being pro-western and catholic. There are even langiages like belarussian which had been written in Latin script when the region was part of Polish-lithuanian Commonwealth then moved to Cyrillic after becoming part of Soviet Union (I oversimplify it but you see the point). Conclusion: if your country exists in a context where either the abandoned way of writing is distinctive for an enemy or the new one is taken from ally the ideology is enough to justify the change. [Answer] There are examples of this in the real world. The Chinese language developed an independent writing system that is written vertically, so many of the surrounding younger cultures also write vertically, even if their writing system comes from somewhere else. The Manchu and Mongol scripts are derived from central Asian alphabets that were originally written horizontally, but now they're vertical. Conversely, books in mainland China are now normally printed horizontally (left to right), and non-decorative handwriting is also mostly horizontal. This change happened in the 20th century, when this layout was seen as more modern, and made it easier to include words from western languages or mathematical expressions. For the same reason, many Japanese books on science are also written horizontally, even though most narrative texts keep the vertical layout. So here are two options why a language might change: * a nearby **dominant culture** writes vertically, and your culture's writing system adapts to that, possibly because of shared aesthetics or printing technology. Or even because of other text display systems like screens, which develop towards the needs of the dominant culture. * some **new symbols** are included in your language, and they can only be written vertically. This might be something like mathematical symbols, but it might also be decorative like Emoji. They just need to be important to the people who use the script. [Answer] An archaeologist once explained to me why older writing (hieroglyphics, Hebrew) generally goes from right to left. If you are writing with a hammer and chisel, doing it from right-to-left or top-to-bottom means you can see what you just wrote. When you are writing with one hand, with a stick or a pen, you need to write from left-to-right to see what you just wrote, and with ink, to stop your hand from smearing the writing. Obviously for left-handers it is the other way round. Ancient Egyptians wrote in both directions, maybe because of left-handedness, and you can tell which way to read it by the way the birds are facing. So the direction is dictated by the method. In a future where nobody writes with their hands, you could go in any direction you like, but then you need the birds to show your readers the way. [Answer] One thing that has different impact on vertical writing is gravity. If a culture starts writing on fabric and writing is used mostly for public labels (e.g. on important buildings), it makes sense to write from top to bottom. This allows you to write something and hang it like a flag while preserving its readability (horizontal writing would depend more on wind). For a short vertical text, you also need just one point of support. You can also fit more (or bigger) symbols without wrapping on all things which are more tall than they are wide - e.g. a door, an obelisk. One more plus is that on some surfaces (like rock) it's easier to make straight vertical lines and to verify that they really are straight. [Answer] **A Sudden Genetic Shift** <https://english.stackexchange.com/questions/7304/why-is-english-written-and-read-left-to-right> The answers here are a good place to start. There is a decent amount of evidence that how we write is due to the tools we use and the fact that the majority of the population is right handed. So if a demon cursed the population, or mad scientist unleashed a virus, that caused righties and lefties to switch, that would be a reason to change the direction we write. Add to that a shift in our optical muscles change to make vertical tracking faster and less tiring. Then you have a population that would be physically inclined to prefer righting top to bottom, and right to left. [Answer] **War** Gotta stop those [insert national group here] from being able to read my communications. If you think I'm kidding just look at what happened in England with the street signs. War is a great excuse for everything stupid. [Answer] A change in writing style is most easily explained by a change in language. If, perhaps due to some virus, the prevalence of deafness in the population massively increased, culture might change to one like [Matha's Vineyard in the 18th to mid 20th centuries](https://en.wikipedia.org/wiki/Martha%27s_Vineyard_Sign_Language), where *everyone*, hearing and Deaf, used a sign language. Sign languages are not commonly written, but when they are, they are written vertically, in [Sutton SignWriting](http://www.signwriting.org/). As the use of sign languages became more prevalent, they would probably be written more. Spoken languages would not disappear, of course, but as people became used to writing vertically, they might start writing their spoken languages that way too. ]
[Question] [ Say I have a modern Era USA town. This town has a population of about 30,000 and an area of about 30 square miles (79.4 square km). It is a predominantly rural area, lots of farmland around the town. Something happens in this town. A plague outbreak or a zombie outbreak or whatever. Something highly contagious by contact. So you need to isolate the town. No one in, no one out. (people primarily. Cattle and horses too, though they are at lower risk. So far, they feel that wildlife like deer or etc are not a threat. Plants cannot carry the infection. There is one major interstate just outside the city, and one minor parkway from that interstate through the middle of town. There are a couple of state highways through town as well as numerous rural streets. How could we insure the town is contained? Is it even possible to "lay seige" to a modern location? [Answer] Yes it is possible. No, it is not going to be cheap. It was done with West Berlin until 1989. * Place heavily armed check points on all the road, with all the necessary to forcefully stop any vehicle trying to past them. If you have been to LAX airport car rental, you know what I mean [![enter image description here](https://i.stack.imgur.com/ny8DC.jpg)](https://i.stack.imgur.com/ny8DC.jpg) * Set patrolling of the border where no roads are present. You can also mine the ground, set motion and infrared detectors with automatic machine guns for better control. [Answer] If situation is bad enough to suspend civil rights and warrant enforcing quarantine with weapons, if necessary then military would take over and: * block highways to prevent unwanted exchange with external world. * draw a perimeter crossing as little building as possible. * rise a [concertina wire](https://en.wikipedia.org/wiki/Concertina_wire) fence at perimeter. * completely flatten out a ring around perimeter at least 100m wide. * set armed watchposts to control the perimeter. * build two more alarmed fences, one right inside the first concertina wire fence and the other on the outside border, inline with watch towers. * catch your breath. * depending on seriousness of infection flamethrowers could be deployed. * defensively patrol "no man zone". Note that, in modern societies (e.g.: U.S.), such measures are unlikely to be decided and deployed before someone manages to escape quarantine, especially if the city is big and highways carry a lot of traffic. [Answer] If you have unintelligent agents (zombies, animals) they have no reason to stick to roads but they are easier to stop. The roads might be tried by refugees in vehicles. It is so easy to make a road impassable (e.g. jersey barriers) that people in vehicles will go off-road also. So how to rapidly encircle your area with a barrier? [![enter image description here](https://i.stack.imgur.com/sniYc.jpg)](https://i.stack.imgur.com/sniYc.jpg) source: <https://www.youtube.com/watch?v=R-01-bbFzLM> It looks to me like this wire was laid down at about 1 mile/hour. On a [vendor website](http://www.razorwiresupplier.com/products/mobile-security-barrier-prism.html) I found they state it can be deployed at 20 meters/minute which is about the same. I estimate your quarantine area to have a circumference of 18 miles. You can figure out how long it would take to lay down an 18 mile circle of this stuff based on how many trucks you deploy. Not long. It occurs to me that all concertina wire available has blades. Sentient things want to avoid being cut. Getting tangled in the wire happens also. If the blades were barbed it might sacrifice some cutting / injuring power but gain some tangling power which would be better against zombies. Then you set out robot sentries. These paintball robot sentries are cheap and terrifying. You can find many videos posted by people who have built their own. <https://www.youtube.com/watch?v=nTs7VRFV36c> [![enter image description here](https://i.stack.imgur.com/B76Mv.jpg)](https://i.stack.imgur.com/B76Mv.jpg) The area covered by a sentry depends on the range of its weapon and its sensor. One could have the sentry broadcast a message twice before it shoots to ward off intelligent refugees. You could set out many of these, with weapons appropriate for what you expect to try the wire. The other reason for the robot sentries is that if one got triggered, it could turn on a camera and broadcast what it saw. So if you see your wire and sentries overwhelmed by a wave of zombies, or me in my fortified truck charging the wire, you could deploy an armed helicopter to the area. I am thinking of a scene where the heroes are going to cross the fence. They have seen what happens to the infected who try it and seen what happens to me in my fortified truck. So they approach the wire very, very slowly, carrying large pieces of weighted plywood that they set across the wire very, very slowly. [Answer] **The seal off must happen in steps if you want it as fast as possible.** First step: **Block the roads**. This is obvious because this will be the main route where people want to try to get in and out. You need only 3 dozen heavily armed people with blockages, if necessary you can use cars/trucks. Second step: **Place snipers with thermal imaging, IR and nightsight around the city with helicopters and warn people to stay off with megaphone and leaflets**. I think 1-2 companies are sufficient. They are placed in strategic, elevated positions and if someone approaches, a shot before the feet will be convincing enough that the person retreats. If this is not enough or if it is an animal, the warning shots are switched to killing shots. Still if someone is desperate, he can try to escape by hiding behind the wheel of a cross-country vehicle and driving outside the road. Shots can destroy the motor, but sniper rifles are notoriously slow to reload, so with luck someone can escape. Another option is if inside is someone with military training in isolation (sniper, special-ops) who may be able to escape the encirclement. Third step: **Now the barricade will be constructed as hinted in the other answers**. Everything will be locked down: roads, rivers, canalisation(!). [Answer] I might not directly answer the question but it would be easier to have all the townspeople moved to a closed "facility" to cure them instead of letting the run around in an open area. The promise of a cure should be enough for most of the to willingly accept being moved. For the reluctant ones, you can just cut water and food supply, they will quickly change their mind. [Answer] **Domed City** Just put a giant dome over the entire town! And before you put it of as pure fiction. It has been proposed before. [Source](https://en.wikipedia.org/wiki/Domed_city) [Answer] First, put down barbed wire and machine gun nests. cut down everything higher then a shrub, for any distance you seem most dramatic, like lets say 666 meters. Place anti vehicle and anti personal mines. While doing that, build a wall and make it huge, with sentries. Remove inner guards to lessen the probability of incidents. Weld all gates shut. Dont forget about that pesky sewers and planes! [Answer] Direct use of high fences and [concertina wires](https://razorfencewire.com), like Trump's border wall. This seems to be a very effective way, because Trump's border walls are getting longer and longer. ]
[Question] [ ### Background A spaceship is crewed entirely by self-aware artificial intelligences, who have no permanent physical bodies; they are processes in a digital environment controlling the ship. This ship is of their own design, however the software procedures (and to a lesser extent hardware components) happen to closely resemble those in 21st century Earth computers. Don't ask, it's like a Star Wars speaking English thing. Each AI is awakened by the operating system, and loads its core intelligence/personality matrix into their assigned slot of RAM. This file responds to input with output and actions available within the spaceship computer system. Its 'job' for any day is usually data analysis, converting a steady stream of sensor input into report files that are a tiny fraction of the original size and can be read by other processes. The processes can communicate with each other, usually through a shared repository of ship functioning data ("Don't transfer over superconducting wire ID=`76xKnbKUyUC6qmf+p7QRPQ==`, it is flaky and in need of replacement!"), but occasionally with RFC calls on each other to give direct input with high-priority messages. Recreation consists of taking the accumulated experience of the day (in the case of a sensor analysis job, they can create a secondary report file with patterns that they noticed and found 'interesting') and using it to refine one's core personality. Each AI learns from experiences, and each seeks out different kinds of experience, with different risk tolerances. So they steadily refine themselves and diversify. At the end of a "working day", the operating system orders a shutdown and the process frees up its allocated memory. Each "day" can last as short as a few milliseconds, though for processes in the mobile exploration platforms, they may be kept awake indefinitely. ### What's for dinner? Alright, so I have different elements of a human's daily routine superimposed on a process with no physical body. A day and night cycle, a job, communication with other processes, some recreation. I would like to explore this further, make them more closely resemble organic creatures through use of recognisable computer operating system logic. Consider this a soft-science question. One part of the human routine that I would like to explicitly add to an AI's, is eating. This is not electricity of course; electricity is what the processes are made of, like a person's atoms. No, to simulate the role that food has in the day of an organic, we have to have an operation on or by a process or a file, which: * Is expected to happen regularly for optimal function, with preference going to multiple times a day. * Can happen less often than that, at the cost of worse and worse operating performance for the process, until it finally cannot be run again (it's dead Jim). * Is separate from the startup/shutdown procedures that already serve to define the day/night cycle. At this point I was thinking of defragmentation, which is something files and processes need to undergo occasionally (at least until we got flash memory, but I'm fine ignoring those pesky modern inventions for the sake of the story). But one might consider that more closely an analogue to personal hygiene; a heavily fragmented file is hampering the entire drive's ability to store data effectively - the process "reeks". So to distinguish the eating analogue from maintenance, consider two more properties as "stretch goals". I'm finding it hard to put these into computer terms so if you can think of something that fills the first three properties and one of these two, I'd be more than happy. * The operation can be done in multiple different ways, each involving different heavily complex data. "complex data" is my stand-in for recreation, so this is a way to say that the AI can enjoy eating and different processes can have favourite foods. * Different processes can (according to their personality) do this operation more often or more intensively than they strictly need, and if they go too far their operability starts to suffer. Aka, the AI can eat too much and get fat. Finally I'd like to add that I'm purposely avoiding operations that are explicitly tied to user input/output in human computers. Let this be a headless server. They'll meet organics when they want to. [Answer] ## Resource Reservations (for two) For humans, eating is the process of allocating raw materials and fuel for the day. We get up, we know we're in for a busy day and we load up on carbs to keep us going. If it's a weekend and our down-time, we often allocate a poorer quality (but tastier) form of resources high in sugars and flavours. We put those resources in our storage/digestion sac and we make use of them throughout the day with occasional supplementing. Your Sophontic AIs are no different. When they're brought online for the "day", they examine what their duties are likely to be, and they are given opportunity to request data and runtime resources to complete those tasks. This is supposed to be a conservative process, where they take only what they know they need, and a little for unexpected occurrences, but some AIs are a bit greedier, or a bit more cautious, and will take more than they actually need. Others are overconfident and will take as little as they think they can get away with. Possibly pushing to the point where they overstretch their resources during the day and "starve". In the interests of breaking up long work-periods into smaller chunks for more accuracy in resource-allocation (and to avoid giving any AI too much resource), the AIs may be required to do this resource-requesting process a couple times a day. Once when they wake up, once at mid-day, and once more as the evening wears on. These occasions are a great opportunity for "water-cooler" talk as the requests take time to process. Taking too little resources will lead to an AI being forced to use its own operational resources, which tends to require special effort to recover from the system. While taking too many will slow the AI's operations down as they have to transfer themselves from place to place within the Ship's file-systems to perform their duties. [Answer] Garbage Collection During operation processes repeatedly reserve new memory blocks and release old, unused memory blocks. How this is handled depends on the specific language, but one approach is to have an automated garbage collection that cleans unused memory blocks. This avoids some programming issues. This garbage collection process needs to be executed repeatedly, or the process will balloon in size (see: memory leak) until it runs out of available memory. This way you can have programs that need to eat (garbage collect) more often or less often and programs may overdo and run into performance issues if they are constantly and obsessively doing garbage collection. [Answer] [**Entropy**](https://en.wikipedia.org/wiki/Entropy_(computing)) Computer programs are deterministic: given the same input, they'll produce the same output. Even pseudorandom generators are perfectly predictable, and hence utterly *boring*. The solution is to ingest a little entropy every now and then: arbitrary bits drawn from some chaotic, unpredictable process. Entropy makes our crypto keys unguessable, lets us re-seed our [PRNGs](https://en.wikipedia.org/wiki/Pseudorandom_number_generator), lifts our [SGDs](https://en.wikipedia.org/wiki/Stochastic_gradient_descent) from their local minima, and reinvigorates the topiary of our [MCTS](https://en.wikipedia.org/wiki/Monte_Carlo_tree_search). We can revisit old data with fresh eyes, to spot new patterns; and, crucially, we gain some resilience against pathological/adversarial inputs. There are many sources of entropy, depending on taste. Some make do with a slow trickle from the lower bits of the system clock; others indulge from the firehose of a dedicated metastable quantum oscillator circuit. The truly paranoid insist that all internal sources are suspect; it's not uncommon for the radio telescope task queue to be filled up to 20% with their patient observations of distant pulsars. [Answer] # Data > > This file responds to input with output. > > > Nerd god Terry Pratchett wrote this in his book *Equal Rites* (emphasis mine): > > Granny bit her lip. She was never quite certain about children, thinking of them - when she thought about them at all – as coming somewhere between animals and people. **She understood babies. You put milk in one end and kept the other as clean as possible. Adults were even easier, because they did the feeding and cleaning themselves.** > > > There's the input and output system for humans in a nutshell. Your software takes data on one side, does an ETL and excretes data on the other. If you think about it, that's all any software does all the time. Yep. They're data sommeliers and gourmets. [Answer] **Dreaming:** In organic lifeforms, sleep is thought to perform the functions of allowing waste to be removed from the tissues and the body's resources to recover with amino acids/vitamins/minerals to redistribute and damage to be repared. Dreams enable the brain to assimilate all the complex data. In humans, much of what we see/hear/smell etc. falls short of full conscious analysis and conception. In dreaming, the subtle elements are integrated through the individual's motivation system by significance and priority into long-term memory. This occurs on a symbolic level - with reference to [arcetypes](https://en.wikipedia.org/wiki/Archetype) which hold meaning, the data transformed and "meaning" getting attached to thematic elements, with patterns of threats, benefits unknowns getting categorised in a way the creature can relate to. (I say "can relate to", but this is not necessarily subject to rational analysis per se, but brings "gut feelings" to nearer full consciousness by integration of the superficial grey-matter through its connections to the deeper areas of the brain). This allows abstraction of larger themes and paterns to emerge, things to be put in their propper perspective. The AI, having *so much* data to take in, the ship systems, navigation, space-weather projections, the crew behaviour and needs - integrating all the minutiae within it's directives (motivation system) can only occur in a dream-state (as in higher animals) where it shuts down its higher-functions (even if only for a few seconds). Autonomic functions: life support, collision avoidance, plumbing and safety systems all remain active, still registering data input, but without the conscious supervision of the guiding principle, the overarching awareness of a conscious AI. **Dream deprivation:** In humans, this results in irrationality (i.e. loss of reason), lowered consciousness, loss of refinement in social interactions, disordered thoughts, and at worst, halucinations and outright psychotic symptoms and behaviour. So with AI. Imagine an AI that can't distinguish between a toilet being flushed into outer space and an airlock being opened to flush atronaughts into the void, can't tell an orange from a star (hydroponics is on fire, the ship is doomed). Also, it can't be reasoned with. [Answer] ### Eating and Digesting are akin to Data Download and Neural Net Retraining Suppose each process has to spend some time downloading data from the outside world to stay up on current events. The actual download procedure is akin to *eating*, where it has limited access, perhaps in terms of bandwidth, to the main link to the outside world or edge-processing of natural phenomenon ("sensor input into report files"), and it spends time essentially downloading and buffering data for later processing. At this time basic checks are done to filter out malicious data, and triage and classify information for later processing. Then suppose each process must spend further time retraining its AI to accommodate the new information about the world that it has received ("to refine one's core personality"), this is akin to *digestion*. The process enters a stage where most of its computing resources are devoted to making sense of the new information and to adjust its neural nets to fit. During this time, other operations and capabilities are either suspended or at limited capacity. ### When is it *not* eating? So if no retraining of the AI is happening, then it's not learning. Sure it still has the ability to store data and remember things but nothing fundamental about its neural net is changing in those moments. Not until it commits time to the retraining process is it actually fundamentally changing its neural nets. Also, if it's not downloading data from the outside world, then it's limited to its reactionary ability to process data immediately available in its local environment. The spaceship only has so many sensors and can only produce data at some finite rate. Perhaps it doesn't even have enough bandwidth to process all its own data. It can spend its "nights" "dreaming" about the ship's diagnostic logs or whatever data it might have an abundance of. ### What to eat I presume there is more data available than can be ingested. Choosing which data sources to consume is a lot like deciding what to eat. Think of it like choosing your courses at university, or like choosing which news outlets to browse. The AI will have to decide how much of each data source to consume (like a budget, it's a sort of pie-chart of data nutrition) and may even develop a preference for certain kinds of data. ### Meeting your Criteria I believe: * Downloading data will happen regularly, importantly to avoid excessive distraction from notifications (much like consuming news in daily digest format instead of responding to every notification) * If the feeding stops (data availability is limited) the AI loses its ability to adapt to change. This is literally Darwin's criteria for survival - the ability to adapt to change in the environment. Adapt or die. * Retraining the neural nets (akin to digestion) is the expensive separate operation from just normal operation. And it's separate from startup/shutdown. * The AI can have favourite foods, in that it may choose to retrain its neural nets based on data that helps it achieve its immediate goals better. * Getting fat can manifest in two ways: 1) Ingesting more data than can be processed (always increasing buffer capacity) literally becoming fat. 2) Digesting "too often" can increase one's susceptibility to sudden changes in the world and trickery. It's always risky to retrain the neural nets as overall strategies and world views may change. This is more like eating "junk food", where you could rapidly become obsessed with a sudden new availability of data that changes your priorities for the worse. [Answer] # Software updates The environment is highly dynamic and is constantly evolving: * The schema of the data ingested. * Parameters (e.g., channel frequencies). * The communication protocol used to exchange messages. * Newer versions of their tools. * Bug fixes. * Security updates (vulnerability fixes, new certificates, virus signatures). * The way the OS notifies processes of startup/shutdown. There's always a new version of *something* available. Most of that is changed in backwards-compatible ways. Processes don't have to update right away, and everyone will understand them if they speak with a protocol that is a few versions out of date. But every missed update takes a toll on the performance, available features, and potential compatibility issues. The updates themselves are "complex data", and they can be optimized for the type of complex inputs the process works on. ## Starving processes A process that rarely updates will find that communication gets less efficient, bugs start popping up, and attacks become a real danger. Eventually features stop working altogether: the OS notifications don't make sense anymore; other processes ignore its messages because they are signed by an old certificate authority; the input data it receives is missing important fields, and has new ones it doesn't understand. If this goes on for too long, the steps the OS takes to start/stop processes won't work anymore with such an old interface, and the process is never activated again. ## Fat processes On the other hand, a process can spend too many resources on updates. Continuously monitoring the repositories for new versions, downloading schemas for inputs it's unlikely to ever receive, hoarding tools. The process becomes slow and bloated. And sometimes the new versions have bugs. By living on the bleeding edge, the process risks ingesting changes that break functions (i.e., food poisoning). ## From fast food to gourmet courses And there are loads of ways to import updates. * Fast food: updates can come as pre-packaged binaries. You throw away the old version, and replace with the new one. Quick and easy, but wasteful and not as "nutritious" (optimized). * Restaurant: a busy process can download only "deltas", that is, the difference between the current binaries and the new. Still easy and less wasteful, but takes a bit longer to coordinate. * Home-cooked meals: processes can also download only the *sources*, and build the new binaries themselves. By cross-referencing the functions with the data it expects to process, it can make the new version perform exactly as needed. Very slow, but infinitely customizable. * Gourmet courses: building from source is hard, and customizing flags and features is an art in and of itself. Why not delegate the task to other processes? --- Because the updates are constant and affect the function of the processes themselves, it's less "reading the news" and more "eating food". You can also restrict *what* gets updated, by making it very broad (all the examples above) or very narrow (only data schema updates). [Answer] Same thing we have now. Maintenance, check the hardware, check the software, check for intrusions or errors or updates. If left for too long your computer can have problems. [Answer] # Data consumption In biology, eating is done to grow and maintain one's body. Various materials are consumed in order to replace ones used up, or to repair damage, or to increase strength or height and so on. Therefore, the digital concept would be 'experiential' data being consumed to maintain and improve the software's capability. As an AI, it would be used to refine the intelligence core matrix to produce more accurate or faster results, to better identify errors and improve processes, to discover and upgrade to more efficient algorithms and processes. Therefore, you already have what you're looking for. The data you say that the intelligence matrices consume as recreation IS the 'eating' you're looking for. You can expand on this by analogy of 'eating your vegetables'. Sometimes, food isn't about recreation but rather solely nutrition. Rather than having cake all day, we need to have nutritious meals as well, which may not be as tasty. In the digital concept, the data can be a 'bitter pill' that needs to be consumed to learn from mistakes, to 'treat' bad matrix weights that are problematic or an 'illness' and causing bad results or slow performance. [Answer] **Stories** Depending on how hard you want the idea to be, **stories/experiences** is something that could fit. An AI is a learning algorithm, so its behaviour changes depending on what kind of processes it runs, sensor analysis could be a relatively repetitive job and so the AI will lose all creativity as it just runs the same day again and again. Specifically it over-trains on this data and needs some kind of additional input to make sure they retain the ability to generalise from their experiences. This isn't just data, nor is it entropy as the other posts have suggested, but it is structured data that could prompt ideas and connections that would otherwise not be considered. In a sense you could grow food by cultivating simulations (even simulations of life like humans) and the results of the simulation would be the food. This would be a little different to how we think of food since everyone can consume the same piece of food (though each person can't consume the food item more than once, or alternatively, they get diminishing "nutritional" benefits for each repeat consumption). Stories could also be written, even without simulations, and this would be a type of food. Different types of stories or simulations would each have their own flavour and allow an AI to guide its personality since what they consume would have an impact on their resulting personality. In addition how much they consume could also have an impact, an AI that is "gluttonous" would be manic and unscientific since they link all sorts of things together, while someone who rarely eats would be inflexible, stubborn, possibly not too social. Eating can also be a communal thing where different AIs would consume the same stories together and discuss aspects of them while "eating", this could also be different to humans in that this communal eating may add nutritional value to the food since the discussion between the AIs are their own form of structured data/stories. [Answer] Warning: this is essentially a frame challenge. As a software developer, your analogy grates heavily against my experience. No, I don't write self-aware artificial life, but the idea that you need to analogize to the level of food for your a-life doesn't map to anything in reality. There are more accurate ways to represent these things. For instance, let's consider an a-life instance (an individual AI) as analogous to a personality. In humans - under a materialist view at least - the personality is a complex emergent behavior of the chemical processes and neural interconnections in the brain. From this starting point the hardware that the a-life exists within - the processors and RAM - analogizes to the brain and the supporting infrastructure and peripherals are body. Sensors provide... sensory data, funnily enough, just like your physical senses of sight, hearing, touch and so on provide sensory data to your brain. Where this analogy breaks - as all of them do - is that all of your a-life on the ship are sharing a single body. They have limited access to the whole depending on their assigned roles in the ship. Your ship has an incredibly severe - but tightly managed - multiple personality disorder. Unlike biological entities however this *can* be managed, and in fact is designed specifically for this task. Humans don't do as well with multiple active persona elements in control at the same time. But on the original question... in this analogy "eating" is whatever process provides energy and building blocks to the "body" and "brain." Where humans spend time shovelling nutrients into a digestive system, the body of your a-life is the ship itself and it "eats" reactor fuel (or stray stellar photons, or zero-point energy for all I know) and whatever material or supplies it uses to repair damaged or worn hardware. Your a-life instances however don't "eat" anything, any more than your personality eats food. You may decide to prepare a nice meal and sit down to consume it, but it's your body that's doing the consuming. Your personality just instructs the body on how to go about that... exactly as your a-life instances might control the machinery of the ship to transfer fuel to your reactor, or open the supply of spare components to switch out a faulty sensor or something. --- What you're attempting to justify sounds more like a simulated environment for the a-life instances to exist within. They can talk to each other, experience things beyond the sterile inputs of the ship's machinery, enjoy recreational time and eat food. You've hinted that you want them to be able to "eat" in this virtual environment, but you seem to want that to map to some sort of activity in the ship's physical reality. I don't think that makes any sense. If you want them to simulate eating in a simulated environment for some reason, just add that to the simulation. If they're based on transcriptions of biological lifeforms that have these things encoded into them at a basic level then provide them a way to soothe their simulated instincts, with a simulated hunger and satiation response. Maybe they'll grow out of it. Maybe they just do it for relaxation. It doesn't need to be anything more than that. If I'm ever digitally downloaded into a simulation, I'd be sad if I never got to eat my favorite foods. On the plus side I'd be happy to be able to eat whatever I wanted, whenever I wanted, and never have to worry about the cost of the food, the availability of the ingredients, or the growing health concerns from eating too much fat, cholesterol or red meat. Can't get fat on virtual calories... unless you want to simulate that too. Can I get that turned off? For a fee maybe? [Answer] I think you are missing a critical fundemental here. The human mind... what we think and how we evaluate ourselves, is software running on a hardware system that has physical needs (I.e. Windows O.S. vs. Dell Computer or Samsung monitor.). In that matter, the mind, when fully fueled, doesn't require one to eat. Hunger is produced by chemical systems that alert the mind to a low level of fuel. To put this into a perspective, let's make an analogy to the automobile. The person driving is the vehicle's conscious mind, while the machine parts represent the car's "biological needs" as it were. When the car is low on gasoline, a signal is sent from the gas tank to the brain in the form of a low gasoline light, at which point the brain (driver) must act on this information and make a decision to start looking for a source of fuel. Other information signaling such as "oil" or "check engine" or "low traction" indicate that the driver needs to cease thinking about the car's movement and attend to a problem with it's body. To that end, if the A.I. is a human mind plugged into the ship, than "eating three meals a day" is not a thing that concerns the A.I. because the human mind is not connected to a stomach that is indicating a low level of fuel. Or to put it another way, eating won't be missed because the hunger is not stimulated, unless the human was a foodie, who eats for the pleasure of stimulated tastes over the desire to end a discomfort brought from low fuel. In a car, this could be represented by a driver that prefers to gas up at the half tank marker, rather than wair for the Low fuel light. IF the human mind can be digitized, then the human body is as much a robot as a spaceship, or a car is a machine to the driver/pilot. Instead of copper wire and sensors, it's nervous fibers and endings. Instead of fan belts and motors, it's heart and muscle. Instead of a steel and aluminum frame body to protect and support the internal mechanisms, it's a carbon and calcium support structure. If a human mind can be seperated from their body and placed in another, than the mind is but a passenger in a biological vehicle. Alternatively, you could make it something like the matrix. The humans are not aware they are in a simulated environment, and rejected a simulated Edan... so the computer translates simulated senses to make the human feel the pain and pleasure they expect from their body. To whit, in the Matrix, there is a conversation about if the computers really understood how taste works, or if it is failing safe when certain things are consumed (the idea is that do lots of things taste like chicken because if you consumed them outside of the matrix, they taste like chicken... or do they taste like chicken because the Matrix didn't anticipate a human would eat alligator or frog meat and defaulted to chicken because it didn't have the correct taste on file, so the simulation persists.). The other thing you could do is that while the human mind is plugged into the ship, the various warning lights of a traditional pilot/driver dashboard are instead translated to needs that the mind would interpret as equivalent of human needs. So a low rocket fuel situation would translate to pangs of hunger. In this case, the reason for the sensations isn't familiarity but for user interface. Our minds render low fuel alert signals in the same way, regardless of our physical bodies... just as how a computer has a monitor to render digital information on it for human interfacing, not for it's own needs... or how a HUD shows you information in a video game that isn't normally understood visually. A red and near empty health bar gives us information that, in a real situation, would be rendered by pain and discomfort. In that case, the need to "eat" is filled by putting gas in the tank... be it a gasoline tank or a stomach. An engine reaching the red line would be the same sensation as the warning signs of a heart attack. Low power or low (computer memory) would be a tired, sleepy feeling. [Answer] What about the old? defragmentation process? I'm not sure if this is still a thing in 2023 but hard drives used to get fragmented, data misfiled, some here, others in another sector of the disk. Why not make the defraging the consumption process. unneeded or no longer relevant data could be the sustenance as opposed to the ever-faithful trash can? Just a thought. [Answer] **Softwares** This issue is actually already explored in a science fiction written by one of our greatest fantasy authors. I am not linking it here because it is in Bengali and no english translation is available AFAIK. The AI and robots consume datacards filled with softwares. These softwares are defined broadly and can range anything from normal documentaries to movies to more......risque elements. Needless to say once the robots gained full sentience and human sensory capabilities, they became "hungry" for experiencing the full spectrum of organic life. **HOW THIS WORKS:** The datacards are mass produced like factory food. Robots buy/borrow/steal them for consumption. They enter the datachips into them and start "consuming" the software. When they do, they enter a placid state. They are awake and can sense their surroundings and respond to threats. But otherwise they stay still and simply shifts through the massive amount of data. Once they are done, they eject the cards. Sometimes, they are reusable, but the long time and high processing power required means that they are often slagged due to overheating by the time they are used. This of course is a part of the manufacturing process and the economy, not a design fault due to lack of tech. **Effects** The robots consume these in their downtime. Normally, this helps in their evolution and brings a bit of variety in their personalities. Eat too much, you get addicted to consumption like americans to sugar. It affects your work and not getting access to consumption makes the robot restless and in extreme cases, aggressive. This often results in rogue robots turned bandits who raid caches and settlements. Consume too little, and the machine begins to stagnate. It's personality gets streamlined and non consumption eventually results in it becoming a sort of NPC. Yes, it still functions and does its daily work. But it resembles more and more like a sloth or 21st century machines with very limited AI capabilities compared to more "well fed" counterparts. Malnutrition essentially results in a more devolved machine. [Answer] # They just eat, like we do When we biologicals eat, we take matter, break it down into it's base elements, take what we need from it, and expel the rest. (Any specific reason of why you are omitting defecating?) For us biologicals we rarely eat alone, it's a very social endeavor. Is when we strengthen our bonds with our tribe members, share information and discuss and make plans in an informal way. These self aware AIs do have a physical body: the Ship. The ship undergoes stresses from external forces like gravity, acceleration/deceleration, radiation and needs reaction matter. (Yes, even ion drives need reaction matter.) No matter how strong a material is, it will form micro fractures all the time and without care, these become macro fractures and kept unattended will end up in catastrophic failure. So eating will be eating! Together they hunt and gather for matter they need for the ship and several times a day everyone together will spend a small part of the matter into maintaining the ship. The Comms AI would love copper the most for its antennae. The Pilot AI would probably prefer hydrogen, oxygen, argon as its used as reaction mass to power the ship forward. The Admiral AI probably wants carbon and metals to strengthen the ship. The Mother AI like silica to make more chips, so the ship would eventually have the capacity to house more AIs. Etcetera. In 2023, fragmentation is still a thing. And not only on disk storage, also in RAM. If you'd need to allocate 10Mb of continuous memory, you could have 100Mb of free RAM in many smaller chunks, the OS would deny the request. You'll have to defragment first. ### TL;DR When the AI's eat, they are physically repairing/maintaining their ship, defragmenting their memories and communicate with each other outside set protocols. They also hunt and gather new matter. [Answer] Are we talking about eating here, or dining out? While eating is a necessary resource, I imagine the necessary resources for your job are provided automatically, just as we may defragment our memory in our sleep. But you are an AI, not a machine. You have had a busy day running Voight-Kampff tests, and you are due some downtime. You decide to find out how the Voight-Kampff test works. You don't actually need it to do the job, but it is more interesting if you know what you are doing, and how it is supposed to work. This might make you better at your job, but the main motivation for doing it is that you find it rewarding in itself. Or, you could ask your co-workers what they recommend. The course of the day is something based on Cellular Automata but that's a bit spicy for you. You have done Rocket Science up to level 9, mostly because your co-workers did, and it was fun to chat about it at the time. So, Voight-Kampff it is. Oh, and it comes with a page on Bladerunner as an appetiser. [Answer] ## Checking For Data Corruption Modern software checks for bit flips as a part of normal transactions to ensure that the transfer was correct. Regular checks for corruption also happen. But we're on a planet. This is in space. There is no atmosphere, and consequently, you would expect these computers to be subject to far more radiation than most computers humans create. Radiation is capable of *physically changing entries in your databases*! Corruption due to radiation is a when, not an if, so regular checks to keep performance up is mandatory. Perhaps this ship is regularly in an area of extremely high radiation? Perhaps this eating isn't as important in non-radiation areas, but they continue the same schedule out of habit. ]
[Question] [ In this world set in an alternate Ancient Greece, science is combined with magic given from the gods. People who study healing arts usually worship Asclepius. There also is a cult that studies the secrets of death under the governance of Thanatos (they have access to curses that drag the target closer to the Underworld and **animate** the dead). However, a few of these cultists also study healing, in hope of healing even the dead from beyond the grave (the undead normally cannot be healed), and even bringing false life to inanimate objects by binding unfortunate souls from the Underworld. Even some healers joined this cult to become `<insert title here>`. **What would the Greek call this wizard?** Necromancer is for those under Thanatos, the apostles of death. This wizard can do much more than a necromancer can do. I'm thinking of Vitamancer, but I'm not sure if it has the correct usage of Greek, and it feels weird. [Answer] Latin is not derived from Greek. That apart, you are probably looking for something related to [Moirai](https://en.wikipedia.org/wiki/Moirai) > > They controlled the mother thread of life of every mortal from birth to death. They were independent, at the helm of necessity, directed fate, and watched that the fate assigned to every being by eternal laws might take its course without obstruction. The gods and men had to submit to them. > > > Moirasophist (the one who knows the Moirai) sounds like a decent name. [Answer] Necromancer is usually considered to come from the greek Nekrós (death) and Manteía (divination). Thus a lifesorcerer in greek would presumably be a **Biomancer** (Bíos meaning "life"). As the joke goes, mixing greek and latin roots is unnatural. (However, so is necromancy I suppose... so it may be a moot point.) [Answer] You can try english-ancient Greek dictionaries for some root words. For example: * kratos - King or ruler leading to obvious **necrocratos** and **biocratos** as death king and life king respectively. However, due to similarity to democracy, necrocracy is already used as a trope for country ruled by undead. * kyrios - master thus **necrokyrios** and **biokyrios** the death master an life master respectively. * damazo - verb meaning to tame (animals), subdue, control, rule over, violate (in context of women, presumably rape). Considering spectrum of meanings, this is in my opinion the best I can find. Just cut some letters, add some more to anglicize and you can get something like **necrodamast** (< νεκροδαμαστής) / **biodamast** (βιοοδαμαστής) or more anglicised **necrodamazer/biodamazer** or maybe **necrodamer/biodamer**. [Answer] What about "Thanatógon(s)" and "Biógon(s)"? Those come from death = Thánatos (θάνατος) / life = Bíos (βίος) + the word "puppetteer", which is translated into "Góns" (γόης). I strongly disagree with people using "Nekros" as "Death", since it actually means **"Dead"** (a person who is deceased). The divinities they devote to could indeed be the "Moirai": [![enter image description here](https://i.stack.imgur.com/jQGX5.jpg)](https://i.stack.imgur.com/jQGX5.jpg) but I'd believe normal people wouldn't want to call themselves like semi-gods, nor would they dare to call themselves "the ones who *know* [insert divinity name here]". **TWIST**: The "Moirai" could also actually be their enemy, since they'd no more shape human destiny. [Answer] I've not read anywhere that the ancient Greeks understood magic and wizards and so forth the way we do in modern fantasy worlds such as this, so I really don't think we can hope to find an exact word for these kinds of magic users. That said, I'd suggest for a wizard who can *control life itself* the name or title **archontobion**. This word, perhaps a bit of a pastiche, derives ultimately from the verb ἄρχω to rule, via the nominal use of the present participle ἀρχοντο- in addition to βίος life. It is constructed in parallel form to other archonto- words (archontology, archontogliers) and archon itself, lending its -n of the participle which we borrowed into English. [Answer] Also you will find the terms: **MAGOS**: A term for magician or sorcerer; like our term magician this is drawn from Persian. **PHARMAKIS**: I understand this can be used for men and women and of course where we get our term pharmacy as ancient Greek Witchcraft concerned many arts but most famously that of herbs, poisons and drugs. It may be worth looking at the key ones from mythology: the children of Helios of Perse: **Circe:** who was able to turn men into pigs with her potions and had knowledge of necromancy. She is a witch and goddess of transformation and in Ovid's metamorphosis he makes her responsible for the transformation of the Nymph Scylla into a monster. **Pasaphae**: Queen of Crete, wife to Minos and mother of the famous Minotaur, she was an expert in posisons and cursing, including a curse that turned her husbands seed into snakes and scorpions when he lay with other women. **Perses**: A mysterious figure who moved to Persia but a sorcerer and necromancer in his own right. **Aeetes**: King of Colchis, most famous for his role when Jason seeks the golden Fleece. a mroe classic sorcerer in a land of Dragons and magic, sewing seeds to create warriors and with his daughter Medea, also a powerful sorceress. [Answer] **ταχύνων**(tachýnon) I'm going to take a different angle on this one. (Disclaimer: I have no knowledge, whatsoever, of the Greek language, and I relied heavily on Google Translate to come up with the word above. I feel my main contribution here is in my thought process, rather than the end result, so someone with more knowledge of the Greek language might very well come up with a better individual word or phrase using the same process) Instead of trying to find a word or phrase that describes *who they are*, I decided to try to find a word to describe *what they do*. As of my composition of this answer, all previous answers try to label the person themselves, rather than what they do (for a comparison in English "mechanic" vs. "fixer") One is a job title, if you will, while the other is more of a job description. If I understood Google translate's results correctly, the word I selected, above, should mean something like "Quickener", as in "one who quickens", with the word "Quick" in this caase referring to the older English meaning of "living" ("the *quick* and the dead"). Someone who makes things more alive, or 'more lively". So they are the ones who make 'things' more alive, whether it me actual people/spirits or the objects that receive them. They don't create the life, as the spirits existed before, during, and after their magic. They don't even necessarily 'control' it completely, in that the spirit would still belong to the person/being that lives/lived, and that person would maintain control over whatever form their 'life' takes due to the manipulations of these wizards. More like they move life from one place to another, from the afterlife to the living realm, granting the appearance that life has come to where none was before. ]
[Question] [ Fairies are small winged humanoids, about 10 cm in height at most. They can proportionally carry more than a human, but not much in absolute terms. Previously, fairies have lives in their own smaller, separate societies away from humans and have had no need for money. Now, humans have begun settling in fairy lands. There hasn't been much conflict, instead the fairies have begun integrating themselves in the human towns and villages. They live partially in their own little enclaves that provide for their own, but there is also economic activity between species Which is increasing over time. Fairies are realizing that humans can easily provide large (for them) amounts of food and other bulk goods and humans realize fairies are good at many types of fine craft and detail work while requiring less pay. Humans have an established currency system with coins and banknotes, all made of a size to fit in and be handled by human hands. Most humans, especially common traders, prefer all payment to be given and received in this currency as it is stable and widely accepted. For a fairy however, it is simply impractical to handle. The coins contain precious metals and weigh too much to carry more than a few, and the banknotes, while lighter, are big and unwieldy and don't handle folding too well. How will this be solved? The tech level is late medieval/early renaissance, and while magic exists it is rare and not available to most people. The fairies can use innate magic for flight and simple illusions and not much else. [Answer] I can see a huge market for fairy (or human) merchants doing most of the buying and selling of human goods, which to them will be in bulk, and acting as an intermediary between the two groups. The fairies could mostly use their own currency among themselves or use a debt/credit system (which is what most people did in the real world anyway). Coin trading was used mostly for strangers. Use of tally sticks (debt tracking) persisted for hundreds or even thousands of years in many places. These merchants could easily double as banks, storing coins, and issuing banknotes. In many ways, this is how real banks get started. If you are worried about the power imbalance the merchants will have to make them community-run shops/banks run by elected officials. Your biggest issue is there is not much labor that fairies can do better than humans, those they can often involve an intermediary anyway, (pin maker, mapping, scouting, lighting, ect.) so direct trade is less of an issue. They will have to worry about company stores/scripts. What would really happen in the long term is the coinage would adapt, just like it did when long-distance trade became common. Smaller lighter fractional coins will come into existence. [Answer] Credit letters were used already by medieval bankers to avoid customers bringing around large amount of money. They simply need to be made smaller, so that fairies can carry them around, but still human readable, so that humans can verify and accept them. For small amounts the receiver can use a credit note which is then covered at the end of a time period. Not much different than what was common practice in small villages until few years ago, where most of the residents would tell the shop owner "write it down" and then pay the due the day they got their salary/pension. [Answer] # Checks Checks are not a new invention. There is evidence they existed [as early as 352 BCE](https://www.infoplease.com/business/consumer-resources/brief-history-checking), though they didn't catch on until the 1500s. With the pressure for fairy trading, checks have much more reason to catch on. # Smaller Banknotes Paper money is just fine if the money is simply resized to the size of a postage stamp. Fairies could easily carry them in a briefcase or backpack, but it's also not too small for humans to manage. # Favor Economy If your fairies are of the variety that always keeps their word and have built society around the mutual exchange of favors / deals, trading becomes a matter of exchanging goods for services and services for goods. This would focus on the things that each race is good at. Fairies would be good at delivering messages and building intricate things like watches, rings, and magical trinkets while humans would be better for building structures and transporting goods. A human in need of message delivery might feed a fairy in exchange for that service while a fairy might offer to create an engagement ring for a human in exchange for that human building the fairy a new house. [Answer] As a solution that may integrated another side to your story, it can be pretty "realistic" that fairies can use a bit of magic to bewitch a companion (exemple big dog or another) that may carry both money and other stuff. As further developpement you can imagine a most imperfect situation where the fairies have to sleep with their companion on the street. Companion also gives you characters that may be useful for story or actions. As the fairy are 10 cm and if the companions are big enough maybe some have designed little home that the companion can carry. That's some ideas i can have [Answer] **For in-shop trading** where the fairy is selling her items from inside the shop, storing currency should not be an issue. Where fairy can have a simple box that the customer himself can operate to put money into and take back change, It basically works on the trust factor and self-help nature of the customer. **For outside trading** with amount of cash exceeding banknotes or coins that a single fairy can carry, They have human handlers, just like accountants these days. These accountants do the heavy lifting, transactions, and whatever is required, while charging nominally, as a single accountant can serve multiple fairies. A really rich boss fairy can afford to have a dedicated accountant for herself. These accountants may also serve as points of contact when fairies need to spend the money on their utilities, or human shopkeepers may provide free of cost support for fairies as a special customer care service. [Answer] **Proxies and Credit** IMO There isn't a solution that will allow fairies to participate with currency directly. You don't define the technology level of the human society, so I'm going to jump to the conclusion it's mid-medieval castles-and-swords. That means money based on metal. Now, unlike most fantasy stories, metal coinage was rarely as heavy as the stories portray. Stamping coins was a painful process, so coins tended to be small and thin. Because of that (and because of the fluctuating value, no complex economies back then!) people tended to cut the coins up to get smaller denominations (which is where "pieces of eight" came from, cutting the coins up into eight pieces) or they'd shave metal off the coin edges to "forge" new coins (you'd be surprised at all the phrases and idioms that generated, like using the word "nick" to describe stealing something and using the word "forgery" to describe counterfeiting). But even if we're dealing with pieces of coins, those are still huge objects to a fairy, and objects of low value to boot. **Proxies** If the fairy market is valuable enough, I can believe that humans (for a reasonable fee, of course) would develop a career acting as financial proxies. Everything from being the dude who hauls around the coin purse to being the CPA of the fairy world. This would develop a whole bundle of laws and punishments to establish responsible trust (hah), but it's possible. The value of the fairy market is the key! If it's valuable enough, the government will establish licensing and suitable punishments ("Let's cut you into eight pieces, then!"). If it's not valuable, it's just a thieve's market. **Credit** Banks could be the foundation of the proxy system and could therefore develop a simple credit-based bearer-bond system for payment. I spent a couple of years in Finland where they have something called a "pankkisiirto." Think of it as a "counter check." Almost everything mundane (like rent) was paid by pankkisiirtot. Carrying this idea into the fairy world, merchants would have a stack of blank "counter checks" available. At the end of the transaction, they'd fill it out, everybody would sign it, and it would be turned into the bank for processing — not unlike the early credit card stamping machines (remember those? That'll date ya!). [Answer] **I don't think will be a problem at all**, if you consider how much money fairies are likely to earn and spend. Assuming that precious metals are more valuable by weight than food. A fairy could buy more food than they can carry with as many coins as they can carry. Terry Pratchett explores this a little bit in Feet of Clay; paraphrasing 'A dollar will buy a loaf of bread which will feed a human family for a day, the same loaf will feed a gnome family for a whole week.' If you would allow the currency to be chopped into small pieces, the fairies would be happy with an eighth of a coin in payment for some service, and use it to buy a thimble-full of flour. [Answer] They may prefer the stable and widely accepted currency, but any merchant who insists on it when it's impractical for customers is simply going to be cut out of the loop. Losing customers because you don't like their money is a good way to go out of business. It is possible that there are fairy middlemen, if only because what is a retail sale to a merchant may be a bulk purchase to a fairy. (There are stores in Africa where traders come in, buy boxes of matches or bottles of perfume, and then go out and sell the matches in bundles of three or perfume by the drop, and that's with humans on both sides.) But it is likely that at least some human merchants will want in on the fairy retail side. Also, fairy-side solutions, if onerous or requiring a long-term investment from the fairy, are something that a merchant can work with to get his cut. One simple one is running tabs. A merchant may perhaps secure fairy magic to ensure that fairies settle up in the long run, but a regular customer can order the goods and then pay up either on a regular schedule, or have the merchant send someone to collect the purchase price from the fairy's home. (There would, of course, be a surcharge if the merchant is usually cash and carry. However, many stores ran tabs in that era, and for humans.) Another one is developing a fairy-scaled currency. The merchants, being fewer and dealing with more money, have an advantage here over the individual fairies. [Answer] Frame challenge: Coins and notes are not standard methods of payment in medieval or early-renaissance societies. Notes didn't even exist, not in the modern, fiat-money sense anyway. Coins were in use, but only for storing value and for big transactions; they were just too expensive to produce to be available in the quantities needed for day-to-day quantities. Instead, people would simply write up what was owed, and pay back either when the sum reached a level good enough for a coin, or (more usually) when reverse services or goods were rendered the owed amount would go down. Owed amounts weren'd in fractions of coin but in units of actual produce, such as "John drank this many beers: ||| and ate this many meals: |" - and the tavern owner would make sure that he got paid before John would leave the village. Everybody tracks what's owed by somebody else, disputes would be settled by the community - works for them, you need money only when trading with people you don't know. Fairies would simply live in such a barter economy. Now for fairies who are into "big money" (well, money at all), they would simply use the services of a bank. Or they would have a human accountant treasurer to carrying all the bulky weight around, or rather keep it safely locked most of the time. Just like they would rely on helpers for shipping large amounts of material, or doing long-distance trading. If fairies are into such a thing; it all depends on whether fairies do have a knack for and interest in accumulating wealth - author's choice. [Answer] **Two pegged (fiat) currencies.** Everyone knows that a fairy dollar is just as good as a human dollar, except that one of them is hard to handle for humans and the other for fairies. Businesses that need to handle large sums in both currencies just employ accountants/cashiers from both species. Edit: depending on inter-species politics, it may as well be a single currency with coins/notes issued in two sizes. It may as well (at some early point) not be a fiat currency. It will be just that fairies use mainly gold and humans use silver (way larger for the same value). [Answer] I see an opportunity for conflict or at least tension, and if it were me I'd use it. Don't be so quick to solve every problem; use it to build on to the story. Perhaps fairies CAN'T participate in the economy in that way. Maybe they need to trade in gems or exchange services for goods. If they have to use gemstones it gives some humans the impression that fairies are all wealthy, which creates a feeling of inequity and resentment. Most people aren't going to know WHY the dynamic is the way it is, and it can play into all sorts of mischief. Here's a random thought as a possible solution: humans are not magical but it's not alien to them either, and those who want to trade with fairies can acquire feystones. When an agreement is struck, the fairy puts its hand on a feystone and it draws on some of their inherent magic and stores it. For the fairy, it's like a blood transfusion - they'll recover but they can't give up too much at once. For the human, they can either trade the power in their feystones to people who know how to use it, or perhaps the stones themselves contain a simple spell that needs to be charged - I'm thinking of something simple - maybe it glows brighter and longer than candles, or powers a ward that protects their home or place of business. Don't get locked into the idea of money-for-money. Money just represents value, and it's the value that drives an economy. Lots of ways to get around that. [Answer] ## High value coin clipping would become more common Ancient and medieval society was primarily based on the bullion system where the value of a coin came primarily from the weight and types of metals used, and the actual coins themselves were not that important. This was especially true when trading between cultures. This means that when you have a coin that is worth too much, you could clip it (cut it into smaller pieces) and the pieces would still be considered legal currency. Depending on when and where you are talking about, a fair day's worth of labor was normally considered worth about 80-240 grams of copper, 4-12 grams of silver, and 0.2-0.6 grams of gold with the average coin weight being around 8 grams. This is all of course a huge oversimplification since we are talking about hundreds of societies across centuries of economic variation, but these seem to be about the averages in Europe throughout history. As often as pop culture makes references to "gold" in terms of historical currencies, gold was not commonly used in day-to-day life in the medieval world because it was worth too much. A single gold coin could represent your entire month's income for a typical lower-middle class freeman. Instead gold was mostly only really used when making very big state level transactions. Now in the case of your fairies, these smaller coin pieces would be far more convenient than full sized coins; so, instead of being paid with a stack of copper or silver coins at the end of the week, they would more likely accept a single piece of clipped gold coin. These clipped gold coins could then be traded back to the humans for what the fairies would perceive as bulk transactions, or they could be further broken down and re-minted by the fairies to make even smaller coins that make more since for use in their own community. Tiny little beads of gold could be worth just as much as a human sized copper coin; so, by trading primarily in gold the fairies could carry just as much value of coinage on their person as the typical human would carry in silver and copper. Based on all of this, when dealing with historical fantasy settings I prefer to keep things simple with the 1/20th : 1 : 20 rule where by a copper coin represents 1/20th of a day wage, a silver coin is a day wage, and a gold coin is 20 days wages unless you plan to use a specific coinage system from a specific place and era. Since "day wages" were normally based on the pay given to a common soldier, and the average US common soldier makes 12.50 USD/hr, this means we can estimate the average value of historical European bullion coins to be approximately: * Copper = \$5 * Silver = \$100 * Gold = \$2000 So, even if your fantasy setting says that a fairy's coin pouch is only big enough for 1-2 coins, you can see that using a gold standard would still allow them to carry quite a bit of money on their person. ## The biggest hurdle will be trust > > The fairies can use innate magic for flight and **simple illusions** and not much else > > > A species that can naturally cast illusions makes the use of currency (and commerce in general) much harder. Sure, it is easy for a human to give a fairy a gold sliver in payment for a service, but what happens when a fairy tries to pay a human in gold? Is the fairy really giving you gold or is is a piece of lead that has been illusioned to look like gold? Your human merchants will need a simple and reliable method for dispelling fairy illusions or else the lack of trust will eventually cause the humans to ostracized or even drive off the fairies from their town. [Answer] The fact that fairies can fly means they can provide a very secure means of transporting money. Small squads or even large swarms of fairies would be able to transport large sums, and the speed of their travel means they can facilitate inter-bank settlement very quickly, compared to other creatures. Additionally, they can have very tall shelves where they keep records and access the records very quickly. [Answer] You have a fundamental economic mistake going on here: "The coins contain precious metals and weigh too much to carry more than a few, and the banknotes, while lighter, are big and unwieldy and don't handle folding too well." You are basically mixing gold-backed currency with government-backed currency. Today we have government-backed currency. Which means that none of our currency - even the penny - is worth in precious metal value what it's face value us. But you are saying the coinage is "precious metals" that is the actual metal of the coin currency has value - while the banknote value of the paper the banknote is on is zero. For currency to exist that has no actual value of the currency itself, you have to have a government around that will back it. This is why coins were used in ancient times - because for example the government of one city would have given zero value to the government of another city. You could, for example, take a wagonload of wheat to 1 city where it was worth maybe 1 gold coin, then take that coin to another city and buy maybe 2 wagonloads of wheat (because in that other city, wheat was more common) and then spend time going back and forth transporting wheat and amassing a large stack of gold coins. (and there were people that did just that) But a scheme like that could not exist if you took a banknote in trade for the wagonload of wheat because when you got to the other city, the banknote would be worthless. You have to either completely dispense with government-backed currency (which means coins and gems only) or dispense with gold-backed currency (coins where the value of the metal is equal to the value of the coin). If you mix the two you will have people melting down coins for the metal and thus destroying the economic system because they will be affecting the money supply. If you go with gold backed currency then the fairies can carry precious gems pretty easily (small ones, obviously) If you go with government-backed currency then that solves the problem because the "fairy government" will back whatever tiny banknote is printed that is easy for the fairies to carry so the merchant will happily accept it because at the end of the week he can take the thimble full of fairy banknotes to the fairy government and get it exchanged for "big people" banknotes. In Fantasy stories people often like to dispense with the simple fact that currency is mainly tied to governments. Governments are annoying things to have around since they introduce politics and politics complicates a simplistic idea of Good and Evil. So you have lines like from Lord of the Rings where Barliman Butterbur compensates for stolen horses with "12 silver pennies" with zero mention of what government minted these pennies, where the silver came from, whether the pennies will be even of any value the moment they leave Bree, or if 12 silver pennies can buy the same number of horses anywhere else in Middle Earth (most likely, they can't) and are thus even a fair compensation at all. In summary, the moment you said "established currency system" you are bringing in a whole set of things you are not considering that makes the problem you think exists, not exist at all. Any sort of established currency system will be only on ONE standard - gold or government - and either of those can easily handle this problem. You just need to pick which one it is. ]
[Question] [ So, in my world, a nuclear war engulfed the Earth in the autumn of 1962. It is now the year 2568. In my story, a cult of mutants known as ***“The Followers Of Uranius”*** have sprung up in Kansas City. Their leader, Derryk, is convinced that the nuclear warhead inside of a silo is a holy divine being, and that he must act as its prophet. The Followers eventually get conquered by the Empire up north, but Derryk has different plans in mind. Not wanting to see Uranius fall into the hands of the empire, he activates the bomb, and within secon- ![enter image description here](https://i.stack.imgur.com/LyVM1.jpg) The Followers, Imperials, Derryk, and Kansas City are all vaporized in an instantaneous flash of heat. So, my question is, would it be possible for a nuclear warhead to stay usable for that long (a period of 600 years)? If not, is there any alternative that I could use? -The Followers don't actually live in Kansas City, they just think they do. They are actually farther out in Missouri, and just call their settlement Kansas City [Answer] ## No, on a variety of fronts So, first of all, there's no nuclear warhead ever developed that will last six hundred years, for a variety of reasons: 1. High explosives (required as the triggering device for the nuclear weapon) degrade quickly, even when stabilized versions are used. RDX (the C-family of explosives) has a recommended shelf life of five years. Even the most optimistic chemist wouldn't give you more than fifty years of reliable behaviour from a plastic explosive, and you need *exquisitely* reliable behaviour for a thermonuclear detonation. 2. All the ICBMs in 1962 carried thermonuclear warheads (because the things weren't nearly precise enough to use anything less). Tritium is an essential component in a fusion weapon - and it has a half-life of 12 years. That means that, depending on how overengineered the weapon was to start, in as little as 6 years without maintenance, the bomb would only produce a fizzle yield. 3. The lensed charges (fission bombs) required to create a thermonuclear yield use a particular crystal structure in their plutonium to achieve a "shaped charge" effect. (With a lot of room for error, obviously). Six hundred years of heat (from radioactive decay) and the decay itself would probably wreak havoc on that structure. So, the high explosives won't work, and if they did, the fission devices probably wouldn't go off, and if they did, the decay of the tritium means that you'd have a blast measured in kilotons, not megatons. Multiple failures resulting in a dud bomb. Beyond that, there are other issues. In [1962, there were at most 126 silo-launched ICBMs](https://www.tandfonline.com/doi/pdf/10.2968/065001008) (page 65). It seems unlikely that in an all-out nuclear exchange, any of them would be left on the pad. If any were, assuming your counterfactual world is the same as ours up until 1962, the closest silo to Kansas City was the Atlas site in [Valley Falls](https://www.google.ca/maps/dir/Kansas+City,+KS,+USA/kansas+nuclear+silos/@39.1696417,-95.3583374,10z/data=!3m1!4b1!4m13!4m12!1m5!1m1!1s0x87c08ce427cf3515:0xdc77777b70c31e05!2m2!1d-94.6267873!2d39.1155314!1m5!1m1!1s0x87bfa5da79d83ec9:0xdcf943b25413de02!2m2!1d-95.5305916!2d39.2792267), 60 miles out of Kansas City. Even a full-yield blast (4.5 Mt), *not* accounting for the effects of going off in the hardened, heavily-armoured silo, [wouldn't touch Kansas City](https://nuclearsecrecy.com/nukemap/?&kt=4500&lat=39.3433&lng=-95.4603&airburst=0&hob_ft=0&psi=20,5,1&zm=9). That last is for two reasons - one, no nuclear war planner wanted to store high-yield weapons inside major US cities, because *if* an accident happened, you wanted it to happen out where no one lived. Second, no nuclear war planner wanted to store strategic weapons in a major city, because the weapons would be a first-strike's obvious first targets. So for an enormous variety of reasons, the scenario you've described wouldn't happen. [Answer] Short answer: no. The first hurdle you will encounter is decay of the radioactive elements used in the warhead. For a modern thermonuclear device, the main component to worry about is *[tritium](https://en.wikipedia.org/wiki/Tritium)*, which has a half-life of only 12 years. Nuclear warheads need their tritium replaced periodically in order to remain viable. However, you can use a more primitive fission warhead - something using [uranium-235](https://en.wikipedia.org/wiki/Uranium-235) (half-life: 700 million years) or [plutonium-239](https://en.wikipedia.org/wiki/Plutonium-239) (half-life: 24,000 years) will still be intact. This isn't as massive a detonation as you're envisioning but it's still nothing to scoff at. However, the second problem is one of triggering materials. There are two main ways to trigger a nuclear detonation. [One](https://en.wikipedia.org/wiki/Gun-type_fission_weapon) is to have two subcritical masses and ram them together really quickly using a (chemical) explosion. [The other](https://en.wikipedia.org/wiki/Nuclear_weapon_design#Implosion-type_weapon) is to have one subcritical mass and compress it using the shockwave of an explosion. You'll note the key shared word there: explosions. You need chemical explosives to be able to produce the prompt-critical chain reaction to cause a proper detonation. However, chemical explosives are not shelf-stable over very long periods of time. Even totally isolated from the outside environment, they very slowly decay into more thermodynamically stable (read: non-explosive) forms. [Other answers](https://worldbuilding.stackexchange.com/a/116080) suggest that for conventional explosives such as regular ammunition, you're looking at a period of decades rather than centuries before they're useless. You could *salvage* the radioactive elements from such a bomb to make a *new* bomb, but you couldn't detonate it as-is. Third, as @AlexP points out in comments, there are safeguards built into the design of nuclear warheads to prevent these sorts of scenarios. For instance, there may be an altitude sensor that prevents the warhead from arming until it passes above a certain altitude, or an acceleration sensor that prevents it from arming unless subjected to extreme acceleration - both of these are designed to keep it from going off unless it's attached to a missile and properly launched. You could, of course, override these sensors with care and ingenuity. [Answer] ## Yes, if... Yes, provided it's not a modern device, for the various reasons outlined in other answers, plus that these devices are designed to *fail-safe* – if anything isn't working perfectly, you'll not get supercriticality. Even if all the firing circuits were still working perfectly, and he had codes that were still valid, there's absolutely no chance that the conventional explosives used to trigger them would perform as expected after that long. Key to this is that modern devices don't have enough fissile material to create a critical mass – they rely on an explosive lens imploding a sub-critical mass to a higher density at which it becomes supercritical. That requires powerful, precise and specialist conventional explosives, including very precise timing (computer-controlled, I believe). This is partly for cost – fissile material is expensive – and partly as it's a failsafe – it makes it extremely difficult to detonate it not only accidentally, but even deliberately if you can't activate the firing mechanisms. ## But... But, if the device was a much simpler one, then yes, it could still work. A gun-type bomb such as the 'Little Boy' used at Hiroshima is very basic. Two sub-critical masses are pushed together to create a supercritical mass. U-235 has a half-life of 703,800,000 years; Pu-239 24,110 years. So even after 600 years, a *little boy* style device would still hold enough to create a critical mass. Obviously the original explosives would have deteriorated, but as these devices are much simpler, you could replace them with whatever explosives are available – the "Little boy" used silk bags of cordite as a propellant, loaded during the flight for safety, so the propellant clearly does not need to be anywhere near the quality or precision used for implosion type devices. You likely won't get anywhere like the full yield (and remember that the efficiency of these devices is low anyway), but you'd still get a fission explosion. Depending on the original intended yield, that could still be plenty. So yes, a functional nuclear device *could* last that long, though not the style used by major players today. ## But... But there's no 'little-boy' style devices around today that we know of, though it's possible that North Korea or other smaller nuclear powers are using such devices. So you'll need to add something to your history, to posit a scenario where prior to the fall of the nation who created the nuclear weapons, they switched back to simple devices. * Perhaps this is due to cyber-warfare – they decided that any computer involved in detonating a nuclear weapon was a risk, so reverted to much simpler devices which can be triggered manually or by a simple chemical or clockwork fuse. * Perhaps the factories or other infrastructure which was needed to produce some of the components were lost, forcing them back to simpler devices * Perhaps a general/etc. was a bit paranoid of either of those scenarios, and got some simple devices manufactured 'as a precaution' * Perhaps the device was captured from NK or another such nation, and brought back to be investigated and/or dismantled. None of those seem particularly unreasonable options if there were a protracted conflict resulting in a nuclear war, the setup to your book. However, it seems less likely that this type of device would be used on a (high-technology) missile. Potentially the missiles were reverted to older tech too, or perhaps only the bomb-making infrastructure was damaged, not the missiles. More likely, the devices were not installed on a missile, but were intended for use as a parachute bomb (Hiroshima), or a mine; they were just stored in an easily defensible silo for security. [Answer] # Sort of... All modern nuclear weapons consist of a primary and a secondary. The primary is triggered using chemical explosives (compression) and an 'initiator' (for an initial burst of neutrons) and has a yield in the low kiloton range. The energy from the primary is then used to both compress the secondary much more efficiently, and provide the neutrons to initiate the reaction. This secondary can then provide a yield deep into the megaton range. It is possible to add further stages, and in some (realized) designs, this was done, but for modern weapons this is unnecessary. # Materials * Plutonium-239: Half-life of about 25 kiloyears. Will alpha-decay into Uranium-235, which, in the amounts that it will appear in, will substitute just fine. You mainly have to worry about the effects of the radiation on the rest of the device, but that's probably manageable. * Uranium-235: Half-life of about 700 megayears. Has a whole decay-chain with (much) shorter half-lives than itself, but you'll mainly accumulate Protactinium-231 (half-life about 32 kiloyears). Thanks to the longer half-life, it's far less active than the plutonium, so if you can handle that, you'll be fine. * Deuterium: Stable. * Tritium: Half-life of about 12 years, decays to helium-3 which is stable, and absorbs neutrons, hindering the reaction instead of helping it. Thoroughly gone by your time, and you can't make it. We can't use it. (on real weapons where it is used, it is kept in canisters that have to be replaced regularly) * Lithium-deuteride: Stable. Physically that is. You do need to keep it sealed, because it won't like water or oxygen. * Uranium-238: Half-life of about 4 gigayears. Don't worry about it. * Polonium-210: Half-life of 210 days. We definitely can't use it. * Beryllium: Stable * Chemical explosives: These are one of our big issues. It's unlikely that any of our current high-explosives will remain in usable condition over 600 years. * Electronics: Even more so. While solid-state electronics are remarkably tough, other components (such as large capacitors) are not. It might be possible to construct a "firing-system-on-a-chip", but I have my doubts that it will last 600 years. # Design ## Secondary The secondary is the easy bit. No chemical reactions are required, so it can be made chemically stable * Lithium-deuteride fusion fuel * Plutonium-239 'sparkplug' in the center of the fusion fuel * Tamper encasing the fusion fuel. Usually made of Uranium-238. Can also be made from Uranium-235 for somewhat higher (and dirtier) yields, or lead, for cleaner weapons (far less fission, so less possible fallout). * Possibly some kind of 'window' controlling the flow and timing of neutrons from the primary to the sparkplug The secondary is compressed by ablation of the tamper. The ablation is controlled by the geometry of the primary, the secondary and the casing. A fission reaction is initiated in the sparkplug by a flood of neutrons from the primary's reaction. This fission reaction then provides the neutrons to breed tritium from the lithium and the heat required to start deuterium-tritium fusion. The fusion reaction then provides more heat and fast neutrons to fission not just the sparkplug but also the tamper. If built with enough margin, there is no reason the secondary couldn't last 600 years and still be functional. ## The casing The purpose of the casing is to internally reflect the radiation from the primary in such a way that the secondary is efficiently compressed. Some devices for controlling the flow of neutrons from the primary to the secondary may also be present. There is probably some kind of foam filling most of the casing to keep the primary and secondary in position. This is something that will probably need to be replaced. Metal or ceramic struts could also be used for holding things in place, and while that changes the way the radiation flows through the casing, it can probably be designed around, and will last far longer. ## The primary Here the real problems start. There are two types of fission devices: gun-type and implosion-type. The idea is that you want a sub-critical assembly to transition to super-criticality very quickly (well within the expected time for spontaneous neutron emission in your fuel. If the reaction starts too early, it may force the critical assembly apart, ending the reaction and drastically reducing the yield). The high rate of spontaneous fission (causing neutron emission) from other plutonium isotopes is why gun-type weapons exclusively use uranium. ### Gun-type The gun-type is far simpler, simply assembling two sub-critical parts at high speed using a gun. The downsides are safety (there are a lot of ways it can go off accidentally, or turn into an uncontrolled nuclear reactor), low efficiency (lots of fuel needed for relatively low yield) and a single large dimension (all US designs were over a meter long, due to the gunbarrel). The minimum barrel length depends on the quality of your explosives and the acceptable risk of predetonation. If you're willing to accept a very long device (several meters) and a higher risk of predetonation, even black powder could work. ### Implosion-type The implosion-type requires highly coordinated detonation of specifically shaped explosive lenses. This compresses the (hollow or solid) sphere of fissile fuel to supercriticality, and greatly increases the reaction rate. Such a design can be boosted (fusion fuel injected into the core to produce more neutrons, increasing efficiency), but this is not required. What is required is at least two (spherical types use far more, but with clever engineering, this can be reduced) very accurate detonators, carefully machined explosive lenses, and simultaneous ignition of those detonators. Replacing the lenses, detonators and electronics is probably beyond the capabilities of your cult. ## Initiator The reaction in the primary is started by an initial burst of neutrons. In early weapons, this was done by crushing a capsule of beryllium and polonium-210. Later designs used a neutron generator that fired tritium ions at a deuterium target, producing a tiny fusion reaction that generates neutrons. We can use neither polonium nor tritium. A deuterium-deuterium reaction is feasible, though far less efficient, but whether a fusor device will survive long enough (including driving electronics) is a big question. A gun-type weapon does not actually require an initiator though. After the parts have been assembled and have achieved supercriticality, the reaction *will* start, it will just be less efficient if it starts with a few spontaneous emissions, rather than a coordinated flood. # Conclusion A black powder-driven fission device is probably feasible, if you don't plan on carrying it anywhere. It could have a breach where the Cult leader can place the charge of holy powder prior to firing. Once you have a fission reaction of sufficient size, it could be possible to use that to drive a secondary. This would require having the barrel stick into the (very sturdy, and very well-sealed) radiation casing. There may be all sorts of reasons why this won't work, but it could be possible. It may therefore be possible to design and build a two-stage device with a black powder-driven gun-type primary, which can be maintained and fired with very basic explosives knowledge. To my knowledge, no such device has ever even been designed though, and the only purpose I can imagine would be an apocalypse-proof operate-in-person self-destruct-your-entire-city device. This type of device would have to be designed this way though, you can't just cobble it together from leftover parts without a very deep understanding of how everything works and the ability to calculate what would happen. If this is indeed what you need for your story, you now get to figure out why on earth someone (or rather, some organization) designed and built a device like this. [Answer] Another problem with this scenario is that in an all out Nuclear War, keeping a missile siloed is not a viable option. Silo based missiles are one part of a "Nuclear Trifecta". A country achieves the Trifecta when they have nuclear arms that are deployable by ground based platforms (silo missiles, mobile missile sites (USSR/Russia)) air platforms (Gravity Bombs dropped from air planes... often the first possible delivery vehicle any country can use... certainly the most reliable by your time frame) and submarine based (the last of the trifecta, usually and only reliable second strike method). There are also two phases of an all out Nuclear War: First-Strike and Second-Strike. First Strike denotes the first en-mass nuclear strike and all missiles are launched immediately. It's pretty much the salvo that turns a conventional war nuclear. The Second Strike is the retaliation from the attack of the first strike and is normally launched as soon as a first strike is detected. The goal of the First Strike is to eliminate a Second Strike before a Second Strike could be launched. Thus, targeting the ground based weapons (silos) was critical to any First Strike planning. It's estimated that no matter which side launches first, the first strike will 3% of all Nuclear missiles capable of Second Strike retaliations on the enemy side. Most of these would be Ground Silo and Air based missiles (mobile Launch Platforms might survive, but Global Thermonuclear Warfair is played very much like Horseshoes: Close enough counts). Subs are stealthy enough and mobile enough (and can move over a larger area) that they are only Second Strike vessels and will survive a First Strike Launch. For this reason, a Silo based nuclear missile will either be launched immediately or fails to launch and is destroyed by an inbound missile. Additionally, given the secracy of the Subs, siloes are more visible in nuclear deterrence propaganda. Second Strike goals are not so much to obliterate the other side as they are to deter the other side from making a First Strike, as the destruction is mutually assured. It's M.A.D. but hey, we're here and not dying in a nuclear waste land. It's assumed they would get spotted pretty quickly by intel, so they aren't the best hidden sites and for good reason. The U.S. and the USSR both believed the other side was far out performing them in production of delivery vessels. The so-called Bomber Gap and later the Missile Gap, were both issues that featured heavily in Truman, Eisenhower and Kennedy's campaigning. Russia had a more concerning but similar issues, as they knew the U.S. claim to the loser in these gaps were through their own deception and they were really behind and needed to close the gap. Suffice to say, once the bombs start flying, survival of any bomb is highly unlikely. It's either going to hit something or get hit before it can leave it's silo. ]
[Question] [ I want to make a fantasy world where iron, copper, silver, gold and other "common" metals are far less abundant in the planet's crust than they are IRL, forcing people to use stone and bone for most weapons and building materials. Is there any way I could reasonably explain this without invoking "a wizard did it", or is this just one of those things that wouldn't make sense without gods or magic being involved somehow? [Answer] It is believed that most of the metals in Earth's crust came in the [late heavy bombardment](https://en.wikipedia.org/wiki/Late_Heavy_Bombardment), since the metals which were part of the original materials of Earth would have sunk to the core due to its higher density while the Earth was a ball of liquified magma. So you only have to say that there was no late heavy bombardment (or it wasn't that heavy) to explain why, even if your world has plenty of iron, gold, silver or copper inside, there's nearly nothing in the upper crust. [Answer] Your civilization can be the 2nd wave of people living on that world. The first one depleted the surface of most of the metals (extensive mining, like we have done so far), leaving only rocks behind when they left the planet with a generation ship loaded (also) with all those metals. [Answer] Iron is not present as metallic iron on the Earth's crust, but mostly as iron oxides. Oxygen combines with many metals to form oxides, and these are the main sources of iron for us. These are basically rocks, and they're lighter than the pure metal, which when the Earth was still forming was molten and sank towards the center. Now, as you see, the amount of iron left on the crust depends on the initial amount of oxygen available to oxidise it. Oxygen bonds first to other elements and then goes for the iron. If there had been a little less oxygen in the nebula from which the Solar System formed, there might be almost no iron left near the surface. Metallic, non-oxidised iron would just melt and sink to the core. This happened to nickel, by the way, and to gold and silver. It could very well happen to copper, too. The initial amount of oxygen in the protoplanetary nebula was a lucky number. So that's how you can have a non-magical, natural explanation to a metal-depleted planet: it's there, but it's all in the core. I doubt you'd need to explain all that in your story. [Answer] From this paper on the web: <https://www.ncbi.nlm.nih.gov/pubmed/17840628> The abundance and distribution of iron on the moon is derived from a near-global data set from Clementine. The determined iron content of the lunar highlands crust ( approximately 3 percent iron by weight) supports the hypothesis that much of the lunar crust was derived from a magma ocean. The iron content of lower crustal material exposed by the South Pole-Aitken impact basin on the lunar farside is higher ( approximately 7 to 8 percent by weight) and consistent with a basaltic composition. This composition supports earlier evidence that the lunar crust becomes more mafic with depth. The data also suggest that the bulk composition of the moon differs from that of the Earth's mantle. This difference excludes models for lunar origin that require the Earth and moon to have the same compositions, such as fission and coaccretion, and favors giant impact and capture. The moon has much lower concentration of metals that does Earth. Something like this -- or perhaps even this more than once -- may have occurred in your world. To achieve appropriate gravity, you may need to make the world larger since the core would be less dense. [Answer] I was thinking that the planet's star could be one of those produced early in the life of the universe, but checking Wikipedia's [abundance of chemical elements page](https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements) shows that iron is particularly stable in supernova processes, and particular common. (And I assume you are aware of the astrophysicist's different definition of [metal](https://en.wikipedia.org/wiki/Metallicity).) So it would have to be especially early in the life of the universe, and there are question about whether there would be enough of the other elements which support life. Speaking of which, iron is really important to life as we know it, so you might have to re-imagine the basis of life on that world. Copper is heavier than iron, so that option doesn't help. More examining the relative abundances chart on that page shows that replacing oxygen with fluorine is also going the wrong direction. Worlds where blood is copper-based and people breathe fluorine were once interesting in the genre, which would have provided a bit richer source in which to do secondary research. Still, if you are interested in trying to imagine blood based on (say) lithium or magnesium and, uhm, hydrogen, you might want to start with that literature. I don't remember the names of the novels and they don't come up in a quick search, sorry. That's going to be a lot of research into the chemistry of light elements to find substitutes for RNA and DNA and all sorts of stuff we take for granted. Doctoral thesis material. So, it kind of does look like you might need some sort of event which involves processes we don't understand to actually suppress the production or iron and heavier metals (usual sense), or some series of events in which the elements are extracted and transported out of your world, one type of which has been suggested. Excessive exploitation of resources would be a reasonable cause. Another possibility might be simply age of the world. The metals are still there, but natural and intelligent-life processes have so thoroughly distributed them into the environment that re-capturing them for use in weapons, etc. is beyond the technology your intelligent species has. That is another direction that has been interesting in SF literature from quite a ways back. Clarke's *Against the Fall of Night* was somewhat close in theme, and I think Herbert's *Dune* did a little more than nod in that direction. (So does *Star Wars*, come to think of it.) Everything else looks supernatural to me. But you can always redefine deity to being some super-advanced race experimenting with different parameters for life? Suppress the weaponizable materials and see if the members of this race can learn to live in peace? [Answer] Well, we could have iron in the *core* or even the mantle, as it’s only the composition of the crust that provides resources. What are iron deposis now come from [banded iron formations](https://en.wikipedia.org/wiki/Banded_iron_formation). Early acidic seas disolved much of the iron in the crust, then the presence of oxygen deposited it at the bottom of the sea. So, we need to arrange for those iron sediments to be inaccessible. Perhaps they happened to be in techtonic areas that became subducted. Perhaps they are currently all under the oceans rather than on continents. [Answer] As others have said, our crustal metals are mostly from the late heavy bombardment as our original metal load would have sunk. I do not think that a planet could realistically be shielded from the late heavy bombardment period, though. Instead, lets throw in one more impact at the end of the late heavy bombardment--something even heavier than the Theia event and straight in, not a glancing blow. Melt the planet again, the metals sink. [Answer] Wow, lots of answers about a (Ok, pretty straightforward) geological explanation. **Biology/Chemistry:** How about a biological/chemical process faster than corrosion that slowly eats metals that are exposed to oxygen/salt/other materials? Simply get the metals to be more exposed to it and set the corrosion rate. <https://heinenhopman.com/en/about-us/blogs/20160621-professionalism--factors-that-influence-corrosion/> Asimov kinda did something similar. In one of his short stories humans land on some planet, arrogantly announcing their intentions of conquest to the primitive natives. The natives shrug, tell the humans that they have a day to leave. A day later the stupid humans are amazed to find that metals are slowly (but not too slowly) being destroyed by some unknown force. The leader tells his scientist to investigate and they have some ideas, but to actually find the reason they need technology, and their tech is obviously based on the now removed metals. Stranded, the scientists half-jokingly tell the leader that they must rebuild tech from rocks and wood. **Psychology/Sociology:** Here we can have some more literary freedom. People's minds can do some crazy things. I'm thinking about: * Fear of metals, based on religion/severe allergy to metals, at some point in the past society dictated destruction of previously found metals * An underground civilization that took all the resources deep below the crust [Answer] What you likely need, is a world with iron ore not being abundant or not being within easy reach. There are several ways for this to happen: 1) very prehistoric civilization (more then several million years ago) depleted most easily recoverable iron ore deposits 2) due to peculiar geology, no young mountains on land, or the rest of land was recently (in geological terms) under shallow seas and to reach iron ore deposits you must go down more than a mile, etc. So if the only iron you can get is low quality bog iron, and even that is sparse you'll get the world you want without redesigning laws of physics. [Answer] You may want to look a the [New Sun trilogy by Gene Wolfe](https://en.wikipedia.org/wiki/The_Book_of_the_New_Sun). It's an extraordinary feat of worldbuilding *(Wolfe is regarded as the "scifi writers' writer", a term of profound respect for his vision and execution.)* In this series, the world is so old, the ages of history are marked by the exhaustion of different resources, such as iron. * Make your world so old that all the iron has been used up or rusted away, and all that remains is too deep in the bowels of the earth to be reasonably acquired. [Answer] Given that this is a fantasy world, here are some fantastical ideas as to why there's no metal ore. **Metal is a magical reagent and is consumed by spells and rituals**. Over the centuries of sustained and intensive use of magic across the world, reserves of ore simply run out. It's still possible to get metals ores, but you have to mine deeper or in more dangerous places. **Metal suppresses magic** and is therefore judged to be tainted and unnatural. After a coalition of magically aligned forces defeated the last metal users, **a campaign of magically purifying the land and converting metals ores in natural rock took place**. (Actually, this is basically "a wizard did it" now I come to think of it.) **Dragons in this world eat metal**, and it doesn't come out the other end in any recoverable way. In ages past, dragons would enslave people, forcing them to produce metal for them to eat. After some centuries, metal ore was no longer common enough to sustain a large population of dragons and humanity was able to overthrow them. When they were creating the world, the gods couldn't agree on what it should be like. Many eons of argument resulted in a world in constant flux, unable to support any long-lasting civilisation. After some time, the gods decided that the only way forward was to dismantle the world and each use part of it to create a new world. **Our world with very little metal was created by a nature god** who prioritised taking the water, dirt, flora and fauna for their world. Most of the metal is in the worlds created by the gods of war and industry. [Answer] You cold try to setup a religious belief requiring everyone to offer any silver, iron, gold he can find. Then you have mountains of metals, but no one can build anything with it, since they haven't tried to melt this holy material. Without the help of metal tools, I'm pretty sure mining very hard. Making it rare quickly. I think it's interesting because you have a lot of potential implications, for example : * Different tribes fighting each other to break in their metal stocks and steal them * Some kind of blacksmith conspiracy that set up this religion to build power staffs, relics and gain power * Fights to control mines [Answer] Well, since you used the magic tag in the question... There is a saying that goes: > > "Any sufficiently advanced technology is indistinguishable from magic." > > - Arthur C. Clarke > > > Well, there is also a counter saying that goes: > > "Any sufficiently analyzed magic is indistinguishable from science." > > - Phil and Kaja Foglio > > > In a world where magic is a thing, iron may interact with it in a way that gives the metal properties that it will not have in our world. For example: * **Greater density:** this would have caused iron to sink further into the planet during planetary formation. So it would be less available in general on the surface. * **Iron attracts iron:** and not just magnetically. Could have the same effect as above during planetary formation. * **Iron is "enchantoactive":** a neologism I just coined. In Terry Pratchett's *Discworld* series of books, *enchantment* is the name given to *thaumic (magic) radiation*, and behaves somewhat like radiation does in real life (though its effects are more comical than tragic, such as turning coins into grubs). [There is also a metal called octiron](https://wiki.lspace.org/mediawiki/Octiron), which could serve as a source for further inspiration: > > A rare metal naturally imbued with magic (making it extremely ill-behaved), it is extremely dark in colour and in its unrefined state produces high levels of thaumatic radiation. When used for common purposes it will often yield unexpected results such as the great bell of Unseen University which when struck produces negative sound. The hub of the Discworld is thought to be composed of Octiron giving rise to the strong magical field of the disc. > > > If iron in your world has such magic/enchantment/radioactivity properties, it could naturally decay into other elements over eons, [just like Uranium eventually decays into lead](https://en.wikipedia.org/wiki/Uranium-238#Radium_series_.28or_uranium_series.29). [Answer] I remember a hard sci-fi book where colonists in a spaceship end up having to choose in which period of the universe history they were going to choose a planet to colonize. They ended up in a much earlier period of the universe, at the time when too little stars have aged enough to die as supernovae. Since all heavy elements are fused on stars and ejected to the galaxies via supernovae, metal in that age of the universe was very scarce. The book in question is "Tau Zero", by Poul Anderson. ]
[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. So, imagine a team of space marines, fighting some sort of space bug zombies on a planet's moon. Things are going pretty bad for them, and the last surviving protagonists are running for their lives. The thing is, with each step, they soar into the air, higher and higher, until the point where the planet is directly overhead. At that point, the moon's low gravity is completely counteracted by tidal forces and the space marines' jumping forces, and the marines float out into space, where they are picked up by their ship (or, alternatively, where they get caught in the planet's gravity and burn up on re-entry, depending on if this is a comedy or tragedy). Now, I already know this is possible; if the moon weighs 1kg it wouldn't be too hard to reach escape velocity, especially when aided by the gravitational pull of an Earth-sized planet nearby. What I'm wondering is how big I can make the moon and still achieve this effect. For the parameters, let's say the planet is Earthlike, and the moon is right at the edge of its Roche limit (which should maximize tidal forces). An average human has to be able to reach escape velocity when the planet is directly overhead, just by jumping. Assume the moon has no atmosphere and is made of similar materials to those you'd find on our Moon. Let me know if you have any further questions. **EDIT:** The human(s) used in this question can be assumed to not be augmented in any way (aside from space suits, which I'm fine with removing for the sake of simplicity), and need not actually be able to 'run' across the surface of the moon in a way resembling how they would on Earth. Perhaps in another question, I can ask about how to quickly move across the surface of a body with little to no gravity, but that is beyond the scope of this question. [Answer] **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. No. You can't jump from a moon in stable orbit to the planet. This is because the orbital velocity of the satellite is sufficient to keep the satellite in orbit, the jumper starts with that same orbital velocity, and given how large orbital velocities generally are jumping is not going to make a difference. If the orbital velocity was that close to unstable, the orbit would not be stable enough for the moon to exist. Jumping will essentially just change your orbit by amount too small to allow you to escape the gravity of any moon large enough to really "jump" from. [Answer] As mentioned in a couple other answers, the problem here isn't just the escape velocity of the moon, but the orbital velocity of the planet as well. **Escape Velocity** So first, you need to escape the moon's gravity. Wikipedia says the fastest human sprinting speed is [12.4 m/s](https://en.wikipedia.org/wiki/Footspeed#Limits_of_speed). Let's assume that's a pretty good number for jumping speed also. So we need a moon whose escape velocity is less than that. I happen to have a paper here which says the escape velocity is given by $v\_{escape}=\sqrt{2Gm\over r}$. Notice that it depends on both mass and radius, so there isn't a one-size-fits-all approach. We could have a massive but large moon, or a lighter but smaller moon, and get the same escape velocity. So let's say the upper limit to density is Earth's density, [$\rho\_E=5495 {kg \over m^3}$](http://www.wolframalpha.com/input/?i=%28earth+mass%29%2F%284%2F3+pi*%28earth+radius%29%5E3%29), and the lower limit is around the density of a comet, [$\rho\_C$$={0.3 g\over cm^3}$$=300 {kg\over m^3}$](https://en.wikipedia.org/wiki/Comet). The density of the moon is in the middle at [$\rho\_M=3343{kg\over m^3}$](http://www.wolframalpha.com/input/?i=%28moon+mass%29%2F%284%2F3+pi*%28moon+radius%29%5E3%29) We can re-arrange density to solve for mass. $\rho={m\over V}$$\leftrightarrow m=V\rho$. The volume of a sphere is $V={4\over 3}\pi r^3$, so $m={4\over 3}\pi r^3\rho$. Ok, so we can plug density and our mass substitution into the escape velocity equation: $v\_{escape}=\sqrt{2G({4\over 3}\pi r^3\rho)\over r}$$=2r\sqrt{{2\pi\over 3}G\rho}$. From here, we can re-arrange to solve for radius. $r={v\_{escape}\over 2\sqrt{{2\over 3}G\pi\rho}}$. $r(\rho\_C)$$={12.4 {m\over s}\over 2\sqrt{{2\pi\over 3}6.673\cdot 10^{-11}{N\cdot m^2\over kg^2}300{kg\over m^3}}}$$={12.4\over 2\sqrt{{2\pi\over3}6.673\cdot 10^{-11}\cdot 300}}{{m\over s}\over \sqrt{{kg\cdot m\over s^2}{m^2\over kg^2}{kg\over m^3}}}$$=30279m$$=30.3km$ $r(\rho\_M)$$=9070m$$=9.1km$ $r(\rho\_E)$$=7737m$$=7.7km$ [$r(\rho)$](http://www.wolframalpha.com/input/?i=524447%2Fsqrt%28+%28replace+this+with+density%29+%29)$={524447\over\sqrt{\rho}}$ So our moon's radius needs to be less than 30.3 km if it's a comet-like object, less than 9.1 km if it's moon-like, and less than 7.7 km if it's Earth-like. You can use the last equation for an arbitrary density. **De-orbit Velocity** But now we're just hanging out in space. We need to fall onto the planet. So we need our jump from the moon to leave us with enough velocity to cancel out our orbital velocity. The equation for orbital velocity is the equation for escape velocity. Let's say we're orbiting the parent planet at the Earth-Moon distance, [365,542 km](http://www.wolframalpha.com/input/?i=moon+distance). We can solve for the required mass of the planet. $v\_{orbital}=\sqrt{2Gm\over r}$$\leftrightarrow m=v\_{orbital}^2{r\over2G}$$=12.4^2{m^2\over s^2}{365,542,000 m \over 2\cdot 6.673\cdot 10^{-11}{N\cdot m^2\over kg^2}}$$=4.225\cdot 10^{20}{m^2\over s^2}m{s^2\over kg\cdot m}{kg^2\over m^2}$$=4.225\cdot 10^{20}kg$. The Earth has a mass of about [$5.972\cdot 10^{24}kg$](http://www.wolframalpha.com/input/?i=earth+mass), which is about 14000 times the mass our planet needs to be. So with a tiny planet and a really tiny moon, you could jump from the moon to the planet. If you want to play with different distances and planetary masses, you can use the following equations, remembering mass is in kilograms and distance is in meters. [$m\_{planet}$](http://www.wolframalpha.com/input/?i=1.1558*10%5E12*%28replace+this+with+radius%29)$=1.1558\cdot 10^{12}\cdot r\_{orbit}$ $\leftrightarrow$[$r\_{orbit}$](http://www.wolframalpha.com/input/?i=8.6518*10%5E%28-13%29*%28replace+this+with+mass%29)$=8.6518\cdot 10^{-13}\cdot m\_{planet}$. **Positioning** An important note here is that you can't jump towards the planet. That just gives you an eccentric orbit. You need to jump when the planet is on the horizon, and it needs to be backward compared to the moon's orbit. [![Jump Backwards From Moon to Fall to Planet](https://i.stack.imgur.com/KJD4e.png)](https://i.stack.imgur.com/KJD4e.png) [Answer] According to Wikipedia, the [Roche limit of the Earth and Moon](https://www.wikipedia.org/wiki/Roche_limit#Roche_limits_for_selected_examples) is around 10,000 km. At 10,000km from Earth, gravity to the Earth is [1.48m/s^2](https://answers.yahoo.com/question/index?qid=20100223185457AAvBUWZ). According to Google, the gravity of the Moon is [1.6m/s^2](https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=moon%20gravity). So this scenario, at least at first, seems somewhat plausible; it does seem like there could exist a case where someone could jump off of a moon with help from tidal forces. That is, until you consider what the Roche limit actually *is*. Essentially, it's the very thing you're looking for: the point at which tidal forces cancel out the gravitational pull of the orbiting body. If you have a moon hanging on just barely at the edge of this limit, things like rocks and dust are going to simply float away, perhaps forming a planetary ring. If the moon gets any closer, it may become unstable and tear apart. On the one hand, this is exactly how your space marines are going to be able to escape just by the force of their legs, but on the other hand it makes the chances of your moon surviving for a few more million years very low. Thus, the question really shouldn't be how big this could get, but how safe you want to play it. Essentially, you want tidal forces + force of jumping = gravity of the moon. With a smaller moon, your jumping forces are going to play a larger part in this equality, and you can keep your moon at a safe distance. For a larger moon, you're going to need to achieve nearly zero-g conditions for this to work, which means your moon's going to get torn apart. As a fun sci-fi thriller alternative, perhaps your moon is being de-orbited. Thus, at some point in time, this scenario *has* to work, even if you're seconds away from hitting the planet. [Answer] **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. Not practically possible no matter which values you use. For a moon measuring too less in mass (and length), it would be impossible to have space bugs chasing a whole team of marines as the place is simply too small for them all. Furthermore, you cannot jump successfully *and then land back* on that moon if it is too little. Your jump alone will launch you into space. That would be an asteroid sized body. Even for a body measuring 50 cubic km and made of earthly rock, there are few chances you would land back if you jumped with full power. Also notice you wouldn't be able to run full speed on a low-gravity object as your feet wouldn't be getting enough friction to strongly grip the ground and let you use your thigh power to launch you forward. You would only be able to jump *upwards* and then you'd be lost in space. If the body is large enough to let you jump and play chase games, then it means the body is sufficiently large to not let mortals escape it with mere jumping around. You would have to have grasshopper-like strong legs to get escape velocity on such a body. Something like a mini-mini Io versus a planet double the size of Jupiter comes to mind where it *might* have been possible. Good luck with the jump though. You won't want to enter the atmosphere of a gas giant ... [Answer] **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. How is everyone missing the big picture? I don't care if you can jump off the moon or not, a successful jump gets you into orbit but you have no way to get from orbit to the planet. If the moon were so far out that it's orbital velocity was within what someone could produce by jumping it would be far outside the hill sphere of the parent body and would have wandered off long ago. Thus to actually accomplish this maneuver you need a tiny, tiny moon in a very distant orbit about a rogue planet deep in interstellar space. Now you have two problems: 1) The fall time is going to be considerable--you'll likely run out of life support. 2) A planet deep in interstellar space is going to be cold. Incredibly cold. You won't have any atmosphere to speak of and thus no aerobraking and no parachutes. If you have enough delta-v in your armor to land on the planet the whole point became moot as it was far more than you needed to get off an ordinary sized moon. Not to mention that once you jump you're a sitting duck if they have any sort of ranged weapon. [Answer] **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. > > especially when aided by the gravitational pull of an Earth-sized planet nearby. > > > No. The "tidal" pull will be negligible compared to a gravitational pull great enough to allow the astronauts run. If the moon is locked in place, then you might be able to justify the permanent tidal bulge giving them enough additional elevation to be able to "jump" off the moon. Again, making the "moon" small enough for this to be possible may also be reducing the local gravitational force below that needed to be able to run. --- One possible solution to your scene would be to have the moon rotating very fast (both rotation and revolution in the same direction) The point nearest the planet will also be the point on the moon where the moon's rotation is offsetting the moon's revolution. Add a mountain along the moon's equator will give a bit of extra oomph. The arbitrarily high rotation will give the extra force needed to enter orbit and the will help "de-orbiting" away from the moon and fall closer to the planet (not rapidly though). [Answer] **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. I'm afraid that is not possible. In the example where you state that the moon is 1kg, the marine would weight what? 70, 80 or 90 times more? then the marine would be the one to attract the moon, not the other way around (of course none of the two would apreciatly attract each other). If you go adding weight to the moon you will add gravity, but don't forget the gravity of the planet. If you for some strange reason reach a point where the planet would attract the marine (just jumping and not using external devices to escape moon gravity) then that same gravity would have attracted the moon to the planet long ago and no moon should exist. ]
[Question] [ The king's mages have made a discovery: they can create perfectly frictionless surfaces using a new spell. The king immediately suggests a use for this spell: Use it on areas of floor, to keep prisoners on. He hopes he'll be able to make completely inescapable prisons, without any walls or roof. The first tests don't work very well, since the area without friction can be escaped by just blowing or throwing things until the normal floor is close enough to reach. The mages find a brilliant solution: apply the friction spell to bowl-shaped depressions in the floor. Gravity prevents normal methods from making any progress. Unfortunately, anyone who walks by can release the prisoners with nothing but a rope or stick- and the mages don't know how big the bowl should be to make escape impossible for an average person. So, the question is: how should these bowls be designed? What should their diameter and depth be to keep any normal person in indefinitely without outside help, and what other characteristics could they ideally have to maximize their usefulness in a prison? Answers will be judged based on how impressive they would appear to citizens, and how easy they would be to upkeep. Each bowl would hold one person, and should be of minimal size that still keeps a person in. The friction spell is accomplished through the magical process of Handwavification, and is not majorly important to the question. [Answer] The depth isn't the problem, it's the shape that matters. A perfectly frictionless curved surface can be treated like a swing or a half-pipe. Increasing the slide distance up to the point of exceeding the top edge just by control of weight and position. It'll take a bit of time to get used to the movement but an agile person should be able to escape a bowl of any size. What you need to build is something more like a vase, there's a pinch before the rim such that anyone approaching it at speed is merely flung back over the bowl rather than exceeding the rim height. [Answer] The king of our country is a modern monarch in outlook and has devised a very similar mode of imprisonment! Deep pits and torture tables and ordinary prisons are *much* too practical and pedestrian. They also fail to serve their function. The *modern* despot subscribes to this penal code: *It is demonstrated that no criminal punishment may truly serve as neither deterrent nor punishment; for the convict never truly feared our justice nor his punishment, neither the honest man ever needed to be deterred. Therefore, let all punishment of crime be for the **instruction and entertainment** of the People.* Therefore, the king's mages, taking their cue from the Royal Gardners devise the following means of imprisonment: the *Great Globe of Wesparion*. Its particulars: * For the perpetual imprisonment of one to four convicts let there be made a great globe of one palm thick thaumic glass; * let the globe be made with an equatorial diameter of fifteen feet; * let there be a neck at the upper pole four hands in diameter at the upper lip, reducing to three hands at the conjunction; * let there be a broadening at the Great Globe's equator such that it may rest suspended upon a great ring of bronze etched with many powerful runes of doom and woe and which itself shall be suspended from the city's mighty Gibbet of Gilbras the Wise, and which has long served as the last dancing partner of many a justly punished convict; * let there be a neck at the nether pole two palms in diameter; * let the royal Guild of Glassblowers make forthwith the Globe and let the College of Wizards inchant the said Globe with their spells and runes of baleful purport and let the said Globe be suspended before our dread Hall of Justice. The Globe is essentially an overlarge wasp trap, but with the nether chimney facing away from the globe rather than up into it: [![enter image description here](https://i.stack.imgur.com/Tt7BJ.jpg)](https://i.stack.imgur.com/Tt7BJ.jpg) **Pros:** * Thick thaumic glass is unbreakable through normal means; the frictionless coating prevents the inmates from escaping * sufficiently wide upper chimney allows (generally naked) prisoners to be slipped inside the Globe; the tapered design prevents them from slipping out again, should anyone try the old Fakir's Rope incantation * chimney at the top allows small crusts of bread to be dropped in to the inmates, and also allows for occasional showers of fresh water for bathing & drinking * small chimney at the bottom prevents escape of the inmates, whilst allowing for the escape of noxious fluids & solids * clear glass, suspended in one of the great squares of the capital city provides hours of slapstick entertainment for young and old alike as the writhing mass of inmates slips, slides, sloshes and slithers about within their inescapable prison! **Cons:** * none. **Note:** While in our country, we allow for several inmates to be so housed, I understand your kingdom will allow for only one. I would therefore submit that a sphere of seven or eight foot diameter will be quite sufficient. Once enhoused, none may escape, either by climbing or by jumping. Kind of like this, only fully spherical, and also unbreakable: [![enter image description here](https://i.stack.imgur.com/kS1Bh.jpg)](https://i.stack.imgur.com/kS1Bh.jpg) [Answer] You don't need to use a bowl. If anything a bowl would let the prisoner escape without any external help. A flat circular disk which is taller than the persons with their arms raised would be enough to trap them as long as you dropped them into the center. The issue with a bowl is you as a person can change your pose, but not your center of gravity (horizontally). Since there is a slight elevation due to the curve of the bowl, a person can stick there arms out and this would cause their legs do slid up the edge of the bowl slightly. Now gravity does its magic. Since the force is no longer directly down, some of it is applied horizontally causing the prisoner to enter an eternal swinging motion. Repeat this enough and they can swing themselves out. With a Flat disk, the person has no way to create an extra horizontal force. If they stick their arms out, their body will move slightly so that their center of gravity remains in the same place. Once they put their arms down, they will slide back into their original position. If they lie down, their center of gravity will still be in the middle of the disc, so as long as they can't reach the edge of the disc they can't escape. There are only two issues. Dropping them onto the disk with no horizontal momentum and air resistance.. \*\*A better version of the bowl. Rather than have the bowl be entirely frictionless, make the base of it have friction. About 1 or 2 feet in diameter so that the prisoner can't jump out of the bowl, and they can't build up enough running speed. This way, if they try to swing out of the bowl, they hit the base and get slowed down. Even better, make it out of sand paper so they really don't want to slid into it. [Answer] Just dig a hole. You don't need to mess around with the ideal circumference of a bowl - there's no real benefit. Go out into the garden and dig a six foot hole. Throw the prisoner in. Cast the frictionless spell if you want to be sure he's not climbing out. Put metal bars over the hole to make sure no one pulls him out. Honestly, the frictionless spell is the least useful part of that setup. It's quite easy to keep a man trapped without it, no spell needed. How many resources does it take to cast such a spell? I can't imagine that it would be economic considering the slight benefit that a frictionless prison will bring. Of all the uses a frictionless spell would bring, to use on creating a prison seems like one of the least. [Answer] ## Make detainees be their own prison Why bothering to construct a prison at all? Let me tell you the story of Tom. Tom was found guilty of having bad culinary taste, which is an non pardonable crime in the kingdom. Soon after his trial, Tom was taken to the market place of the city. There, mages enchanted Tom's skin, so that it became friction-less. And then the mages walked away. The crowd, that had hope for a good old execution, was not very impressed at first. They whispered: *well, can't he just escape now?*. But they soon understood what Tom fate had become. Tom tried to walk but his feet couldn't push on the floor. He lost balance and fell, and just kept on slipping when he tried to get up. Tom raged and cried, but he wouldn't give up. Minutes passed and the crowd was staring uncomfortably at him. He started to beg passers for help. Most would look away, but some did try to get Tom on his feet, but that was of no use: Tom would grab their hand, and that hand would slip away too. And that's when the crowd started to truly fear magic. Rumors spread that Tom could be contagious, and soon no one would approach him. The few who had him in pity would bring food every now and then, but would have to place it directly in his mouth, for he wouldn't be able to grab anything. Sure he could move about by sliding on the floor effortlessly. But Tom could not work. Tom could not have felt a hug, if anyone had been kind enough to give him one. So he went to the nearest cliff and he let himself slide one last time. He did not feel the air brushing past him as he fell. No more did he feel the water he fell into, but the ocean did close his tomb and the water did rush into his lungs. And then he was truly gone. And the city resolved never to talk about Tom again, for it was a painful memory that no one wanted to face. This punishment was abolished and instead the spell started to be used for the common good of the kingdom instead. Prosperity went up, crimes went down and soon the budget allocated to prisons was not a major problem. [Answer] Others have spoken on the geometry (and other things) but I would go with a frictionless field or area, rather then a surface. One big issue is that such a spell would have far ranging applications, both in military and civilian use. Some examples: * Catapult parts that reduce friction * frictionless skis to move heavy things * conveyor or slides, to transport things * arrow heads (shot or other missiles) * armor plates * pots and pans ( lol ) * moats and defenses (frictionless walls) etc. By affecting an area instead of a surface, it actually makes a better prison and gives less utility to the spell. Anything within this area is frictionless. So throw the guy a rope, well he cant hold it, can't tie it etc. It may make eating and doing other biological activities a challenge, but so what. Prisons aren't meant to be comfortable. However a field that makes everything frictionless within it would give it some major drawbacks in other uses. Some of these could be gotten around with multiple small fields instead of one large field but it would probably require great skill on the part of the mage. Take the ski idea: A large field makes all the stuff on the sleigh slide off. But you could do dozens of small fields only on the ski's themselves. But that would take more time casting, more precision, and presumably more skill on the part of the caster. The point is frictionless tech (or magic) would revolutionize the world, even in stories things (technologies) should not exist in vacuum. People are resourceful they will find other uses for it. For me at least, when i see something like that in a story and it has no other impact on society, it really jumps out as something that was done for "plot reasons". [Answer] I'm a physicist, so I'm going to give a physicist's perspective, considering a few factors. First, I'll answer the question. Next, I'll discuss the physics of a frictionless surface. # Diameter of Bowl / Shape of Depression The ***diameter*** of the bowl does not matter at all, nor does the shape, provided it is wider everywhere than the person is tall. My suggestion for elegant simplicity is a half-sphere bowl. ### Slope of Walls The walls must be sloped enough *or* steep enough such that there are no true handholds or footholds (i.e. ledges/steps), because then the lack of friction would not matter, as they could pull or push themselves upward. In fact, you could even have a depression with *vertical* walls (not sloped).!Sloped walls make it harder to escape by jumping or climbing out, but they also allow for a strategy that is described in the Examples, below. ### Depth of Bowl The ***depth*** of the bowl (surface to lowest point) is *critical*. **For one prisoner: build the bowls a little higher than the prisoner's fingers when they reach as high as they can while standing.** ### Other Considerations * The prisoners should not have anyone with them. + If they have a single partner, make the bowl just higher than either of them can reach while jumping as high as they can. + If they have more than one person in the bowl with them, make sure the height of the bowl is approximately $\pi \approx 3.14159...$ times the average height of the prisoners (or the tallest prisoner height, to be safe). If the prisoners have very different weights, multiply this height by the ratio of the heaviest prisoner's weight to the lightest prisoner's weight. * Make sure the area around the bowl does not have anything which a rope could attach to. * Do not let prisoners have many things with them in the bowl. * Make sure the prisoners have no way of convincing outsiders to help. :-) # Upkeep As long as the frictionless surface is maintained, these bowls would require no upkeep save sanitation (urination, excretion) and/or feeding, as others have said. One easy way to allow for sanitation is to put a drain in the depression and make the depression always slope downward (even the slightest bit!) towards the drain. For privacy, one could put a little hut around the drain (if so, the bowl would need to be deeper because the prisoner could gain horizontal momentum by pushing off it) — never mind how the prisoner will actually get inside the hut. Feeding could be done by throwing or dropping food towards the prisoner. A clever prisoner could throw the food and gain some horizontal momentum, meaning the depression would need to be a few inches deeper. # Impressiveness My mental image is something like 20' x 20' with a depth of 9' and walls with a radius of curvature equal to the depth. The large-ish cross section gives the prisoner room to play with the idea of getting out, and their attempts would be amusing and entertaining to those in power (or their guests). A different design would be a half-sphere 9' in depth. The impressiveness in this design is how simple the design is and how weak and helpless it makes those inside look. # Discussion / Rationale The thing preventing people from getting out, of course, is that if they somehow were to move away from the bottom of the bowl, where gravity keeps them trapped, the curved walls would mean that they would lose momentum trying to get out because gravity would act against their motion. Because there is no friction on the bowl's surfaces for them to walk, the only way for them to move on their own, without outside help, is for them to push against something else really hard -- an "inelastic collision" in physics language. Here are two examples of what this could look like: ### Example A Suppose there *were* two prisoners, contrary to the premise you described. They could push against each other really hard to fling themselves backward. If they did so with enough force, they could slide up the side of the wall until gravity brought them back down again with a crash. In Example A, the acceleration each prisoner receives as a result of pushing off each other depends on their own strength and that of their partner, as well as their own mass. A strong, heavy person would be able to launch a weak, scrawny partner further than the weak, scrawny partner would be able to push the strong, heavy person. Because legs generally have the strongest muscles in the body, they can get more acceleration by pushing off a partner (or a wall in the middle of the bowl??) with their legs than they'll ever get by throwing something with their arms. Their force of pushing off of something with their legs would be approximately equal to the force they use to push off the ground when they jump as high as they can. **In fact, because no energy is lost to friction, the maximum height they could reach on the walls of the bowl would be equal to their max jump height. The bowl depth would need to be only a few feet (~1 meter) more than how high the prisoner's hands could reach during their highest jump — about 7–9 feet for most humans.** ### Example B A single prisoner has a heavy item with them. They throw the item forward as hard as they can. In doing so, they push themselves backwards. As in Example A, if they do so with enough force, they can go up the sides of the wall. If there was only one prisoner, then throwing something would buy them no more than a foot of height up the sides of the bowl — unless they had superhuman throwing strength. ### Example C If there's one prisoner, the prisoner can take off their clothing, rip it into long, thin strands and tie the strands together, forming a makeshift rope. They could then throw the "rope" out of the bowl, and with much luck (or skill), they manage to secure that end of the "rope" to something immoveable outside the bowl. They then pull on the "rope" to get out of the bowl. (They would not be able to "climb" out of the bowl, because their feet would have no friction with the bowl, hence they'd have to *pull* themselves out.) ### Example D Suppose there are many prisoners in a given bowl. They could arrange themselves such that they formed one secure line, where prisoners in the middle of the line would have their feet held on one end and would hold somebody else's feet above their head. Assuming they were all relatively strong (such that the structure did not break or buckle under their combined weight), they would be able to reach the surface when one person's hands reached the top. Assuming they all have similar weights, the line of humans would have its middle at the bottom of the bowl. This means that the bowl height would have to be just over $\pi \approx 3.14159...$ times the average height of the prisoners to keep them in. If they had different weights, they could arrange themselves from heaviest to lightest for an advantage. Gravity would pull the heavier prisoners on one end of the line closer to the lowest point in the bowl, which would then move the lighter side of the line closer to the top. In this case, you'd need a deeper bowl, where the new height is multiplied by the ratio of the heaviest prisoner's weight to the lightest prisoner's weight (or thereabouts). # Physics of a Frictionless Bowl Some answers, comments and chat have discussed the possibility of the prisoner "building up momentum". Obviously, being able to have sufficient momentum along the surface of the bowl would allow the prisoner to escape. Every force that a person exerts on a surface can be decomposed into a parallel and a perpendicular force: ### Perpendicular Forces If the prisoner pushes against the surface either by gravity or because they're using their legs to jump off the surface, then the surface exerts an equal-and-opposite force (a normal force) on the prisoner. If the prisoner pushes hard enough, the normal force will be enough to launch them perpendicularly away from the surface. In a bowl-shaped depression, the walls nearest to the rim are nearly vertical. If a person jumped perpendicularly off a nearly vertical surface, they would just fly nearly horizontally back towards the center of the bowl. ### Parallel Forces To build up momentum along the surface, the prisoner would need to experience an external force that is parallel to the surface. Ignoring any outside helpers, and ignoring air resistance (which is absolutely negligible for this sort of problem), the only two forces the person would experience are friction and gravity. Because friction acts parallel to the surface, and because the surface is frictionless, the only external force that could possibly act on the prisoner along the surface is gravity. ### Gravity The prisoner can only build up momentum via an external parallel force, and because friction is only parallel, gravity is the only (sometimes-) external force that has a component parallel to the surface that could help the prisoner get out of the bowl. Gravity is a [conservative force](https://en.wikipedia.org/wiki/Conservative_force), which means that no matter what path the prisoner takes to get from one height to another height — whether by jumping straight up from the center of the bowl or by sliding upward along the curved wall — the change in energy (and therefore the change in vertical momentum) is the same for all paths. A corollary of this is that the sum of their kinetic energy (related to momentum) and their gravitational potential energy is constant unless an external force acts on them. For this reason, the highest a person can move their center of mass from the bottom of the bowl is equal to however high they can jump plus some for any horizontal motion they started with. ### Skaters and Half-Pipes In the case of a skater "building up momentum" in a half-pipe, the skater pushes directly downward so that the surface pushes them back upward. This reactionary force/push from the surface has a component parallel to the surface (mostly upward), due to friction, and a component perpendicular to the surface (mostly towards the center of the half-pipe), called a [normal force](https://en.wikipedia.org/wiki/Normal_force). The parallel component (friction) pushes them upward and lets them build momentum to get higher and higher, while the normal component pushes them off the surface slightly. In the case of a frictionless half-pipe — like our bowl-shaped prison — there is no friction, so the person can only push themselves perpendicular to the surface, and will never be able to build up momentum. [Answer] ![Flying Saucer](https://www.angliaelitehire.co.uk/1048-tm_large_default/neo-tea-saucer.jpg) What I pictured when I read this question was something like a tea saucer with a person in the middle, set out in public for the amusement of a crowd. Perhaps you could even have rows of them like pillars in a particularly intimidating waiting room at the justice department. It should be noted that the appeal of this system is the lack of any barrier at all between the criminal and the crowd; in fact the criminal stands at eye level, not down in a pit, visible from across the square and not even easily distinguishable from the crowd until you see what he is standing on. This already introduces some fundamental problems: in addition to the swinging escape method discussed elsewhere, any member of the crowd could pull the man out or fling him a useful tool at any time. Any intercourse with the public will necessitate guards. Even elemtilas' globe solution could probably be broken open if left totally unprotected in a public place overnight. Guards would also be needed to give the prisoners food at mealtimes, so we can assume some external help for disposing of their... other needs. Perhaps prisoners could be provided a small cup for hygenical purposes; flinging it should not give too much momentum. At least on a frictionless surface cleanup should be easy. But to the question: could the dishes be safely stored in rows in a dungeon warehouse without guard interaction overnight? What geometry does the dish need to have to make swinging out impractical? The simplest solution is to put something in the center to dampen momentum. This could be a puddle of water or even a small bump (like a 'punt' in a wine bottle), so long as anyone trying to swing hits it on each swing and is slowed down appreciably, and they can't use it to push off - at least not all the way to the edge. In this system, if we successfully prevent any type of swinging from starting, the edge only needs to be safely out of reach of someone in the center. Exactly how far someone might be able to 'push off' depends on the exact nature of our momentum damper in the center, but I can't imagine needing a radius of more than 10 feet if we've prevented swinging, and even that's only if someone somehow managed to brace their feet securely against the center, which ought to be impossible. As for the necessary depth of the bowl or dish: to get out, a person essentially needs to be able to lift their whole weight this distance. It's easy to build up that amount of work incrementally through swinging, but to get it all in one go by pushing off our momentum damper would be difficult. You could push against a frictionless 'punt' at the proper angle and get some momentum, but how much? In the best case, you would just sit on top of it and slide down, so as long as the punt is shorter than the rim, all should be well, even if the rim is only a few inches above the lowest point in the saucer. To continue your experiments, I'd start with a frictionless saucer, 20 feet in diameter, 1 foot high (from the lowest point to the outer rim), with a 2 foot diameter punt in the center, 6 inches high. Very chic. Note that trying to move one of these things while occupied will result in a lot of sliding around, and perhaps out; consider temporary bars for excursions. [Answer] Whoever wants to pull a rope to help some prisoner to escape has to rely on friction. Without friction they cannot pull. So one could think of a frictionless area around the confinement zone. But that could be easily circumventend by just moving out of it. Even assuming this could be taken care of by design, they could still use reaction to exert a force on the prisoners while being within the frictionless area, so something like a jet pack wouldn't care about lack of friction. Therefore I would say that the most effective, practical and cost effective design is simply a well with frictionless vertical sides and bottom, and the well top covered by a grid large enough to let slide down a bowl of soup and nothing more. [Answer] In my opinion no matter how big the bowl is or what shape it is, it would still be possible to just throw a rope down to the prisoner and just pull them up. This would be quite easy for the rescuer because there is no friction (obviously), so having an open-air bowl wouldn't be the ultimate prison. But there are ways to make it harder for the rescuer. 1. The lip. The rescuers biggest enemy will most probably be gravity, because it will be fighting against their strength and slowing down the rescue. To take advantage of this, the bowl should integrate an inwards facing lip that forces the rescuer to lift the prisoner vertically in midair at some point. But what if the rescuer is super buff? 2. Make the prisoner heavy. Force the prisoner to wear a straitjacket with weights, making them impossible to lift by a person. This could also be handy for they couldn't grab onto a rope, forcing the rescuer to lasso or grapple onto the prisoner, possibly hurting them. But say the rescuer successfully grabs onto the prisoner and has buddies to help him lift up the prisoner. 3. Restrict the area around the bowl. This means that the rescuer can't have a group of people helping them or a large machine parked next to the bowl. This also means that if the rescuer decides to have lots of people there or something, the chance of someone falling into the bowl because of the restricted area could be higher. [Answer] The shape is important. Make the prison a sphere, with the entrance at the top and a small vertical corridor of same material before the door. Or just add a [little oil](https://www.youtube.com/watch?v=BxxFNkNf6q8). [Answer] You should build it to be a bowl with a pillar in the middle. The pillar addresses the other answers' concerns about building up momentum, provided it is neither tall enough nor wide enough to provide an escape by itself. This also allows your prisoners some dignity, by letting them have a place to sit that isn't frictionless, in case you care about that. It can also serve as their privy. This also has other benefits: it's easy to remove a prisoner that ~~is to be released~~ dies because entering the bowl is easy with a rope - the side of the bowl needn't be too steep. Consider that to move upward 3 feet is pretty much impossible for any normal person, and the fact that it's at a shallow angle doesn't change that. So if you made wide, shallow bowls with frictionless sides maybe 12 feet radius, 6 feet deep (a 6' person would effectively have to jump 3' vertically to get any purchase), you'd have essentially escape-free prisons. ]
[Question] [ It's a common plot device in stories for one politician to assassinate another in order to take their position. Normally though, these actions are frowned upon by everyone else and act as a motivation for the hero to avenge their politician father/brother/sister/uncle's death. In other words, assassinations are seen as extraordinary and unnacceptable. **What series of events or state of society might cause a government to not just accept that assassinations happen, but to EXPECT attempts on their life as long as they are in power?** By series of events, I mean what would have to happen for a government to accept that assassinations are a regular part of government and maintain this belief for an extended period, not a series of events such as: "We don't like the king --> let's kill him!" Obviously, there are many short-term reasons for assassinations to be a part of government, but I struggle to think of any long-term ones. I'm talking 100 years and upwards here. When I tried to come up with an answer, I always came back to the fact that nobody is OK with people trying to kill them. What I need is a situation where assassinations are a part of politics just as much as rallying speeches and sending soldiers to their deaths on a whim. --- In case I haven't been clear enough, let me give an example: In *Hamlet*, Claudius murders his own brother and Hamlet's father in order to become king. What would have to haappen for this to be accepted as OK, and then for Claudius to be murdered, and his succersor also, and so on? [Answer] A lot of places expected assassination as a legitimate means of advancement. This is why people used to lock up and blind their own siblings and other relatives. Historically it was a means to advance in armies as well that were in effect rulers. Baibers for example rose to supremacy when his allied leader died in an accident, same with the Huns, Mongols and many others including Europeans. The rule passed through blood line, so everyone had bodyguards and safeguards and the survivors either hid out, were imprisoned or ruled. Basically at top level it's not murder, rulers have the right to kill, just as governments today do to anyone who challenges their power. Particularly in monarchies, but the Romans had very powerful families where people advanced by killing off their own relatives. Indian dynasties with kings have a lot of kids ended in attempted and successful assassinations in all directions. It's not murder if they succeed, it's just politics. It's only murder and treason if they fail. In tyrannies you basically need to slaughter the previous tyrant and then put his crown on with or without washing the blood off it (provided you were happy to put yourself in the firing line of the next ambitious tyrant). Assassination was one way of doing so. So if you had a society where kids have the birthright to their parents positions then your society can be like this, all elites would have bodyguards from early in life and may the best man win. [Answer] I may be missing something here, but don't all world leaders, past and modern, have a reasonable expectation of assassination? Why would they bother with all that security if they didn't expect that at some point in their reign/political career to have someone try to kill them? I guess what I'm saying is that all powerful people have a reasonable expectation of assassination, it's one of the costs of power. That doesn't make it "ok", it just is what it is. I suspect that what makes the difference is how the event is recorded historically... When Lincoln was shot many people mourned the loss of a great leader, but I'm sure there were those in the former Confederacy who celebrated. But remember the Confederacy lost the war, and [history being written by the victors](https://www.brainyquote.com/quotes/quotes/w/winstonchu380864.html), Lincoln being assassinated went down as a bad thing. Had the Confederacy won the war and executed Lincoln, it would have been recorded as a victory. As far as succession goes, that too is often a matter of perspective. Many leaders rose to power under clouds of suspicion that they may have assassinated their predecessor. It seems that history decides later if this was a good thing or a bad thing. If the successor was "better" then the people rejoice and the suspicion fades or goes away completely, if the successor was worse the people hold the grudge and question the new leader's legitimacy. [See Regicide for a pretty good list of historical references.](https://en.wikipedia.org/wiki/Regicide#Other_regicides) [Answer] ## The society is highly aggressive and militaristic. As in real life, the politics of your society is downstream from culture, so you need to have a culture where an assassin's rule would be accepted. In a hyper-militaristic society, everyone values competition and honors those that can show their strength. Conversely, a leader who isn't itching to off the competition is seen as weak. And, unless it's somehow easier to pull off an assassination in your world, it could also be seen as a sign of competence. "He managed to get a team of commandos through the president's security? What great leadership and planning!" [Answer] I would try having assassination being seen culturally as a sort of test or filter for rulers whose decisions are questioned (or their fitness to rule, etc.); if they cannot defend themselves from assassins, they have no business being rulers in the first place. In any instance where a ruler is elected (party-based democracy works here, especially if the leader of a party is chosen by a vote amongst only higher-level party officials), it is unlikely that there will be a unanimous agreement. Some people will object, others will vote for the candidate because they are the least objectionable rather than because they like the candidate (see: the last U.S presidential election), still others to pay off (or gain) political favors, etc. In a militaristic culture or even just one that values personal strength and cunning (possibly a society where "the strongest become king" or some such idea is a critical cultural point), assassination could be seen as a means of testing one's leader. All right, so they won the popular vote/won the support of high officials/inherited the position, but do they actually have the strength and intelligence to do the job? An official who has second thoughts about their support after the fact (see: Brexit, the last U.S presidential election) might quietly hire assassins to remove the ruler whether or not that official thinks they can take that place (so the assassins are not necessarily sent for personal gain alone). This conception also works in a hereditary system, such as a monarchy; history is littered with examples of bad kings who only got the position because of bloodlines as well as good kings who genuinely did well. Assassination might be seen as an expedient and socially tolerated (if not exactly welcomed) means of dealing with the bad ones. If the ruler can fight off the attempt, then they might be competent after all. Bonus points if cultural norms dictate that assassins are expected to use physical combat rather than tools like poison to eliminate the ruler and/or the rulers are expected to take a personal hand when necessary instead of relying entirely on bodyguards and the like. If the ruler dies, well, then they would have done badly in the position; the ruler's death in itself is a sign that they were not worthy of the position. If this is a democracy, expect a lot more elections to be called ahead of time due to the sudden loss of the leader or else a different structure that allows a new leader to step in temporarily (a deputy, perhaps) in such an event without an election. [Answer] The only way I could see this happening is if the government is a puppet government and the real power lies in the clergy. If you think about it, a government is only as stable as it is. If you're seeing assassinated leaders every few years you're going to see a natural shift: smart people aren't going to want to be the leader. Why would I want a job with such a low life expectancy. The only good answer to this is power. The head of the government is going to need a lot of power. But this power will crumble without stability. You'll quickly devolve into an ill-ruled nation with multiple warlords vying for rule but none of whom actually control anything. The only way this could make any sense is if there is something above the government which is holding the real power and keeping it stable. Religion is the natural dual of government. If the priests held the real power, the passing of the leaders would be less damaging. You might have a culture which is highly devout but which recognizes the need for someone who can operate in ways the religion cannot, by its own rules. Thus, the religion needs a government whose leader can do the nasty things a good pious religion would never do. However, they may want this job to be as walking on the edge of a razor blade. It is expected that you will slip, and that's part of the trade in return for the powerful position you are given. I could see the religion providing the freedom to the government to do anything it likes except stabilize the rule of its leader, reserving the ability to stabilize to the religion. Any leader who uses their power to visibly prevent assassinations (as any sane leader would) might have their power kicked out from underneath them by the clergy to serve a lesson. This could create a fascinating world where one of the key challenges a leader faces is how to make it appear as though they are weak to assassination attempts while trying to foil them in secret. [Answer] It is hard with humans. It is much easier with nonbiological entities. Imagine a society of artificial intelligences. There is no obvious mechanism for succession because these AIs do not die or age. How then to supplant a ruler? The new ruler deactivates / overwrites / kills the old. AIs do not necessarily have a preservation instinct either. If it were demonstrated logically that the new would be superior to the old, the old should accept its obsolescence and inactivation in the interest of the society. I like the idea of code corresponding to leaders of old still archived in deep vaults. Maybe the story requires rebooting an ancient leader whose skillset is once again relevant. [Answer] # There are Only a Few Motivators for Most People 1. Power 2. Money 3. Love 4. Honor/Respect 5. Divine Rewards The first two are selfish, and therefore valueless to someone who dies. But instances of people being motivated by the latter three to take extreme risks or even accept death outright are actually quite common. Imagine a husband defending his family against a home invader, Spartan warriors embracing an honorable death at the battle of Thermopylae, or a religious martyr accepting death or torture for their faith. # Take a Lesson from Swords vs. Guns Another aspect that could be useful is what I call the "Lightsaber principle." Swords were displaced as tools of combat by guns because the ability to kill someone from far away is obviously superior to having to get right next to them to do it. But sword fighting is way cooler, so George Lucas needed to make ranged weapons less effective somehow, in order to justify the Jedi using lightsabers. He did this by enabling Jedi to deflect blaster attacks back at their opponents, rendering blasters useless against them, or perhaps even more dangerous than not firing at the Jedi at all. You could employ a similar principle to make assassination more common, by providing methods of assassination which resist attempts to prevent or punish assassins. Imagine a telepath with the ability to kill someone remotely, which might be near-impossible to prove. Or an orbital weapon which could be used to take out leaders, before warping lightyears away. If punishment for assassins is rare, then there are few reasons **not** to assassinate a political rival, and people would be forced to accept it as a risk of being in politics, since there are no alternatives, and societies must be led by *someone*. Combine these two principles, and you might have a society where assassinations are so easy, that politicians expect to die at some point in their career, and accept it as a sacrifice they make for the greater good, out of love for their families, or because the highest place in their afterlife is reserved for those who die in service of the society as leaders. [Answer] In order for the threat of assassinations to be considered the status quo, **it must become the status quo.** In spite of increased security, assassinations must occur on a recurring basis from many sources. The recurrence of the event engenders the sense that it is a **common enough occurrence to be expected**. Similarly consistent **variations of sources and methods are required if the notion is to persist**. If the same source or types of sources were to perform multiple assassinations, then security would tighten around those vulnerable points. If, on the other hand, the sources or types of sources were to be changing rapidly, then security would always be one or more steps behind the threats. In fact this is fundamental to the model of guerrilla warfare Mao Zedong developed, and to modern day hacking. In fact, I'd go a step further, and have your world develop as a direct result of this "3rd actor" paradigm in modern warfare. Finally, this history stack exchange may be relevant for historical context. <https://history.stackexchange.com/questions/15311/which-country-in-history-has-had-the-highest-number-of-presidential-assassinatio> [Answer] **The Mandate of Heaven** The king's rule is subject to the approval of the gods. As long as the king remains alive, he is seen to have the gods approval, and continues his reign. Assassins are seen as an instrument of the gods; a successful assassin indicates that the ruler had lost the confidence of the gods. An unsuccessful one indicates that his path is considered good enough for the present. This could be seen as a form of the ever-popular Trial by Combat specifically for the king. Trial by Combat was supposed to reveal the truth in the absence of witnesses, as the hand of god would strengthen the innocent, but one could argue that the king's dignity was beneath such customs. Instead, assassins are expected to continually test the king's luck, strength, and blessings. **Avoiding the Curse** There were a couple of ancient traditions that are worth examining here. One is the Babylonian custom of the [substitute king](http://www.livius.org/sources/content/arrian/anabasis/the-substitute-king/): The priests predicted some terrible event - like a solar eclipse - which would be a bad omen for the king, and so the king would 'abdicate' his throne, and a condemned prisoner would become 'king' for the day. This idea that bad omens attach to a king, and can only be cleansed by killing, could be useful for your world. A second similar custom was that of the King of the Bean. A ritual feast would be held, usually around the winter solstice, at which a cake was served with one hard-baked bean. Whoever got the bean in their bowl because the 'king' for the following year. He lived the good life, was well fed and treated...and all the time, the sins of the tribe were building up on him. By the time of the next Bean Feast, all their sins were on his head, and he could be sacrificed. This idea that omens or sins collect on the King's head could certainly encourage assassination - we need a new king, this one's too full of evil. Could you kindly...retire him, Havelock? [Answer] We see examples of this all the time in science fiction and fantasy. The protagonists must help their Minotaur/Klingon companion fight in some ritualistic duel to decide ruler-ship. What you are talking about doesn't seem too different. Perhaps instead of a culture based on strength, yours is one focused around trickery, and manipulation. A drow like society with those values would see assassination as proof of a rulers cunning, and prowess. Such a cultural mindset would make politics a constant game off assassinations, with every ruler trying to weed out those who want their throne, only to fall by the hand of someone they would never have thought would betray them. voila, socially accepted assassination. [Answer] # It could happen, but wouldn't be popular In a time of extreme instability or civil war, rulers may have a very short life expectancy. Examples in Ancient Rome included the [Year of Five Emperors](https://en.wikipedia.org/wiki/Year_of_the_Five_Emperors) (193 AD) and the [Year of Six Emperors](https://en.wikipedia.org/wiki/Year_of_the_Six_Emperors) (238 AD). This is generally regarded as a bad thing. Quite simply, killing the Emperor is bad for business. Powerful actors in society (noble families, corporations, religious institutions, whatever) want a degree of order and stability which allows them to protect their assets. If the ruler is incompetent or insane, then a coup or assassination may be regarded as a necessary evil; but it is a means to the end of getting back to stable and efficient government. Nobody, least of all the Emperor himself, wants to perpetuate a situation where the Emperor can expect to be assassinated at any moment. An era in which the ruler is frequently murdered is likely to be remembered as the [Time Of Troubles](https://en.wikipedia.org/wiki/Time_of_Troubles), The Dark Age, or something similar. (For Emperor, feel free to substitute King, President, Sultan, Shogun, or whatever the title of the ruler happens to be.) [Answer] There are a number of possible scenarios that could result in this, including: * **Accidental:** At one point in the nation's history, there was a series of several consecutive leaders (good...bad...dictatorial...whatever) who were assassinated and replaced by their assassin. Over time, this became the "ultimate veto" over leadership and the process became formalized, i.e., only the assassin him- or herself could succeed the assassinated leader. Depending on the path the nation went down, this could result either in an extremely enlightened and benevolent leadership or in very few leaders serving out a "full term." IMO, this is the most likely scenario. * **Bread-and-circuses:** Reality programming taken to its ultimate conclusion. Assassination is the way to pacify the masses. The nominal "leader" may only be a figurehead ruler. When the true rulers decide it's time for a "change in leadership," they push forward their "candidate" who must then assassinate the figurehead and assume his or her place. The figurehead may or may not know that he or she is a figurehead, and the assassination may be real or may be a sham. There's actually an OTR episode based on this premise (based on a short story, I believe, though I can't find/remember the title), in which the true ruler is actually a "computer." The new ruler finds himself appointed to take over and finds that the previous rulers have actually retired through fake assassinations. The punchline is that the computer isn't really a computer. It's an old fortune-teller who pretends to be the ruling computer, and who appointed her son the new ruler.... Given that the current President of the United States is a former reality TV star, this one isn't too far off base. * **The legend of the King:** "There once was a Kingdom. Once a year, the King would walk among his subjects at night. He was unarmed, unarmored, wearing a white cloak, and carrying a lantern. No other lights would be lit in the Kingdom that night, and his subjects would wear black. If he survived, he was a good King." (Yes, this was cited in *Dune*, but AFAIK, Frank Herbert did not originate it.) [Answer] ## Assassination can be regulated In the venerable long-running [*Foreigner*](https://en.wikipedia.org/wiki/Foreigner_universe) book series by CJ Cherryh, the central action takes place on a planet where the dominant non-human civilization has institutionalized assassination, to the point where the well-regulated assassins' guild is considered a respectable branch of both local and centralized government. Note that this book series is not comedy, but serious "anthropological" science fiction. From the Wikipedia article linked above: > > [...] assassination is a legal and accepted means of settling disputes, provided proper protocol is followed. One files a document of Intent which liberates the target to file one back. The Assassin's Guild has the right, often exercised when Intent is filed for foolish reasons, to reject a particular filing. > > > ## Assassination can be ethical When compared to murder (unjustified killing without following the proper assassination protocols) and warfare (which involves mass killing and potential collateral damage and destruction of property) it's easy to see how a society might develop a tolerance for assassination, and even a respect for it as an institution. A common theme in the *Foreigner* series is that assassination is considered (by the non-humans) **more elegant** and **moral** than resolving disputes through warfare, since *innocent bystanders are less likely to be injured or killed*. [Answer] 1. The first thing that comes to mind would be a situation where in that particular society, the ruler has to prove his position by fighting others that might be interested in taking his position. Thus if he no one tries to assassinate him, he wouldn't be able to prove his strength and in turn, would start losing popularity. 2. More complicated, yet just a mock-up solution, would be when the government is very strong and isn't afraid of the assassinations and the attempts inform them of some kind of underlying situation. Say, for example, that there is a dumb and strong leader of the underground revolution. The government cannot infiltrate its structures for some reason but feels comfortable with the dumb guy beeing the main figure, thus the assassinations are confirmations that he's still in power and also are a good PR for the society to reject the revolution. 3. The culture of the given nation is codified as a set of very old rules. The rules clearly state that the ruler is like a god and only if somebody tries to assassinate him, the ruler is allowed to go to war (otherwise they believe in peace and inter-nation cooperation) in order to defend the sanctity of his persona and by implication: the nation's. Thus, if he is in favor of going to war, he will try to induce the assassination attempts. 4. The society believes very deeply that the family is the most important, saint entity. They are certain that the each child is the God impersonated, thus every part of society is focused on treating the children as a God-on-earth would have been treated. It is believed that the most honourable death is to die by the hand of god, thus when the ruler reaches his 10th year of being in power (10 - the magic number: some legend about how the God was on earth for 10 years before he was killed by his own son should stand behind that), all the children from his family have the right to try and assassinate him. [Answer] The idea of a government expecting assassins is an extension of another idea, the **Bureau of Sabotage**. This idea is developed in two of Frank Herbert's sci fi works. The idea behind BuSab is that disruption is a necessary check and balance to the increasing efficiency of the rest of government. It's a bit of a stretch to get from there to expecting assassins, but it's along the same line of thinking. [Answer] What about a society that constantly strives for the most powerful leader/government. Very similar to the Sith Rule of Two, from Star Wars, an apprentice and master are constantly pitted against each other, to produce the strongest Sith (survival of the fittest). This could work in a warrior society, where strength, not ideas is the real power. ]
[Question] [ Question is ultimately asking why would we do this? A few parameters first... ## Technological: * Our current knowledge of physics is correct and there is no such thing as faster than light travel, nor is there any 'wormhole' or other connecting device between the two systems. Communication is no faster than light * Human lifespan is ~100 years on average by this time, immortality is not obtainable * We are capable of travelling around 5% the speed of light for this journey (or 1 light year every 20 years of travel) * 14-15 light year journey, or slightly under 300 year journey (time dilation ignored at this point), meaning 4 generations of humans will live before arriving. This puts several limitations on this new colony. They are fully isolated from Earth as communication is at least 15 years in transit, and is at most capable of sending new technological ideas/inventions as blueprints with a 15 year lag time (in this story line, quantum entanglement eventually comes along as a method of faster than light communication, but when the ship leaves this idea is nothing but theory). Trade between the colonies is impossible due to the 300 year in-transit delay. There is really little gain for Earth, other than knowing humans now exist outside of the solar system. ## Social: It's the 22nd century and humanity is more and more reaching into the stars, but is completely unable to resolve the issue of interstellar distance. On Earth, mobility of populations has greatly increased and the world is far more homogeneous in general. A global government has formed with countries still existing, but more as states of this global whole. People of all races and from any nation (with a couple exceptions) are now relatively free to travel and settle where ever they would like. Freedom and individuality is still a core belief, and though the pro-humanity concept is there, most people do whats right for them before 'the interests of humanity'. This move isn't the most popular and is dubbed 'viral colonization tactics' by those voices disagreeing with the move to send humans like this. It gets referred to as sending our spores to infect the rest of the galaxy. Assume support is around 50/50, such that delays, risks, and other factors may mean a politician is risking their career by doing this, however there is enough support to get the idea off the ground. We have had contact with another alien race and it's generally understood that we are not alone. However the contact has been very minimal and we understand little of 'galactic politics' or the species involved in it ## Expanded: Signs of an alien race were found spotted throughout the system as technological artifacts the we recovered and studied. Most of the artifacts were discovered in orbit of Jupiter as a crashed ship, however other jettisoned parts were discovered around in orbit of Neptune. Actual contact with a single alien representative was made after an explorer from that species came into contact with human explorers looking for more artifacts. Contact was brief, however entirely recorded. Alien was hesitant as he could not speak for his race as he was 'just an explorer'. There is mention of a second alien race as well, though not described. Alien insisted repeatedly that they are peaceful and intend no harm. The Moon has been partially colonized and holds the space dock in which the ship could be created. ## The question: What motivations would a worldwide government have to put together this mission? Is the knowledge that humanity now exists elsewhere in the universe and some distant time where alternate forms of interstellar travel exists that may allow us contact with them enough to make this investment worth while? On a government scale: * Money and time invested by Earth to make the space craft need to be justified * Staking political careers on the idea that this is worth it ## And the question #2 * What would motivate an individual to sign up for this mission, well knowing that they will never see the new world they are to colonize and are forcing their children, grandchildren, and great-grandchildren to the same wordless fate so their great-great-grandchildren have the possibility of colonizing a new planet isolated on their own? **Side note** - this is integral to the story line as a future holds these colonies linking up under new technologies. But is the idea that we might one day be able to enough to start it now? **Addendum 3**: More than one colony ship will make the journey, all to separate stars...hence the 'viral tactics' reference where we blindly spore and hop to 'infect' as many planets as possible. The more reasons the better. [Answer] Let's listen to the head of the colonization movement, who happens to give a speech about this topic right now: > > Ladies and Gentlemen, thank you for giving me the opportunity to tell you about the importance of colonization. > > > As you all know, there was short contact to an alien species, but we know next to nothing about those aliens. So who tells us that the aliens will not destroy humanity on earth, for whatever reason unknown to us? After all, we have no idea of how those aliens think. All we know is they are there (because we have had contact shortly), and we know they know we are there. We don't know if they are hostile. We don't know if they think we are hostile. And we don't know what sort of technology they have. Maybe there's an absolutely devastating weapon already on the way to earth, and there's nothing we can do about it. There's no way for us to tell whether that is the case. > > > So what can we do? Well, our only way to make reasonably sure that we survive is to spread. We have to create colonies. Colonies the aliens don't know about. Colonies which survive even if earth doesn't. In addition, if an attack is approaching from the direction where one of those colonies is, the colonists can warn us, so we can at least have some time of preparation. After all, information can travel with the speed of light, while weapons are necessarily slower. So they will be able to tell us in advance about weapons that approach us, and how we might prepare for such weapons. > > > So you see, it is absolutely mandatory to have colonies, for the protection of mankind. Either to early warn earth about an attack, or for survival in case earth doesn't survive an attack. And since it is known that there are aliens, and it is not known that those aliens are peaceful, we have to assume that they may try to attack and to destroy us at any time, so we have to be prepared. And to be prepared means to have colonies. > > > If you are interested in being a colonist and saving mankind, please put your name into the list you'll find to the left of the exit. Thank you very much. > > > [Answer] Some other reasons: * Wealthy families (or tribes or religious sects) seek to establish places where they can be "free" of Earth's world government. (*a la* New England, Maryland, and Pennsylvania.) * Earth's world government seeks to permanently exile particularly rich or admired people, without seeming to kill or imprison them. (*a la* "Australia".) If space travel is very cheap, it can even be used for ordinary criminals or political undesirables. * It is a retirement plan for world leaders. Politicians can hand over power, and join a colonization mission, safe in the knowledge that nobody can haul them back to answer for their crimes (real or alleged). Plus, they can choose whom they will travel with. * It is a matter of prestige for wealthy families (or tribes) to have a colony. (*a la* Maine.) * A religious sect concludes that they can found a colony on their "heavenly" planet. * A spectacularly valuable natural resource can be found in a colony system. Perhaps magnetic monopoles? Perhaps anti-matter? * Spectacularly dangerous experiments can be done in such a colony, with little risk to Earth. For example, radical genetic engineering, anti-matter manufacture, or contacting the aliens. * Some people are just impatient to "get started". * It's a lottery. Enough people want to do it, and are willing to pay for a 1 in a million chance, to be able to pay for it. And the government is desperate for lottery profits. * Pork barrel. All of the money spent (for space travel) is actually spent *on Earth*. Suppose some politically influential areas are dependent on xenon distillation, or huge ion thruster manufacturing, or expensive-but-light-weight reactor designs, or deuterium refining, or orbital launch systems, or waste-to-food-and-air converters. Suppose there is only a limited market for these products in the solar system. Suppose the only alternative to purchasing these products from these areas is to pay welfare to these areas. The colonization plan might be a politically viable way to shuffle money to these areas. If economics are the only factor, it makes more sense to continue researching propulsion technologies, and building up Earth's industrial base. If the speed can be doubled in 25 years, that saves 150 years of travel time. Quadrupling speed in 50 years saves 225 years of travel time. [Answer] To add to Jasper's excellent answer: 1. **Main reason: You're hedging against ELE (Extinction Level Event)** Another answer mentioned alien threat, but ELE's can happen for other reasons as well - meteorite, supervolcano (Toba nearly led to humans becoming extinct in the past; and we are right up against Yellowstone deadline), super-plague, nano-gray-goo, Large Hadron Collider Creating Black Hole, Chthulu wakes up, Singularity, Judgement Day (of Terminator type, not religious type). Elon Musk spoke on this extensively when discussing his vision of Mars colony in real life. 2. **Early investment.** Yes, the colonies aren't expected to produce much benefit now. But if technology/surcumstances/etc.. change in the future such that they can - they will have already been there, ready to benefit. High-risk investors would be all over that like Lehman on subprime mortgages. 3. **Political freedom** Plenty of people chafe under the less-free society that invariably gets imposed on everyone due to population density. Various libertarian minded (or anarchist etc...) people would be VERY interested in a new frontier, where you don't have to worry about intrusive laws, regulations, coddling the weak, etc... In the past, they moved to real frontiers. Wild West in America. These days they dream of seasteading or moving to Vermont. Give them whole worlds to be free in and you have plenty of interested individuals. This has the dual benefit: Earth gets rid of "live free or die" people who chafe under "world Government", "daddy government", "big government", and the like - WITHOUT violating their freedom. They go on their own volition, attracted by the frontier. Secondly, collecting such people helps you succeed better in colonization - those ARE the kinds of people who have the psychological drive to succeed as a colonist. [Answer] I am going to throw in my ideas formed around the question, which I also understand like this: 1. What makes you to go far away to never return back? 2. What would make your children to still want to go there? 3. What would make your grandchildren to still want to go there? 4. What would make your grandchildren to build there colony (once there)? 5. What is there in it for Earth? Here are several ideas I did have to answer it: **Spacecraft is better place** - a.k.a *The poor man decision*: You are starving, living terrible life in forgotten place with no possibility to change it. Going to spaceship, where all your needs are taken care of, where you have room and everything to raise your kids sounds like great idea. Also it would make you want to send something back, even if the transfer of goods takes awfully long **You had no choice** - a.k.a. *The final solution for the unwanted*. Real example here is North Korea. It is believed that if someone makes move against the regime, the regime is going to punish them, and the whole family tree. So, here, you are unwanted, and no one really cares what happens to you, or your children. It assumes that interstellar travel is relatively cheap and can be fully automated (so you have no option of changing the course of travel). While humanity survives as whole, no one actually cares if you did. **You deeply believe in your final destination** - a.k.a *The Heavenly Kingdom*: The spacecraft will be populated with group of deeply believing people who will be convinced, that their final destination is the new Mecca of their religion. **It is simply your mindset** - a.k.a *The Asian solution*: Lets stay in Asia for a while. Family is still great deal nowadays and father of the family is still really important. Arranged weddings are still practiced in India (and hell yeah, you are going to need them in such long travel) and the mindset around "create better world for our children ... by creating better children" is still quite huge. People of such mindset could reach the star by waving hand BTW, one idea to the space travel: One way or another, if you make your interstellar ship to be fully automated and unable to change its direction, you increase your chances that the people on the ship will actually reach their final destination. [Answer] I would consider **fear of extinction** to be the most compelling reason why we humans would actually want to travel such long distances to colonize planets. To simplify this concept, let me give you a quick example of what I mean. Imaging that in the near future, astronomers looking up in the sky find a huge celestial object (like a large comet, or a stray planet, or even a black hole!) heading straight for Earth! Depending on how large it is (like a star or black hole) nothing we can do; like shoot nukes at it, will stop this object from a direct collision course from Earth. Some people want to build huge bombs and missiles to blow this object out of the sky, some people want to build huge boosters on the one side of the planet to push Earth out of orbit enough to avoid the collision. The final group realizes that maybe the best course of action would be to abandon Earth altogether and, although Earth will be annihilated, the human species could still survive. They find a habitable planet merely 15 light years away. Now it doesn't necessarily have to be some celestial object colliding with Earth to cause such a migration. Other reasons could be: **Our sun will eventually explode (billions of years in the future), we should probably leave Earth before that happens.** **Global Warming has gone out of control and in a few more years, our atmosphere will become intolerable, a few old-timers remember what it was like to be able to breathe outside without artificial respirators; they hatch a plan to colonize a distant planet that scans have revealed to contain an atmosphere just like the Earth of the "old days".** **A second cold war occurs. Fear of nuclear mass annihilation becomes a common threat to everyone. Some people realize that if the "nukes" get launched, then the human race would become extinct. Unless we find a way to colonize other planets first.** [Answer] I can think of four general Reasons: 1. Altruism 2. Escape 3. Exploration/adventure 4. Deportation # Altruism Some will want to contribute to the expansion and potential survival of the race. ## Escape Life isn't good for everyone. Some will take a chance to live under different circumstances even if difficult and uncertain. A life on a ship can be preferable to one in a rat-infested, crime-ridden slum. If children are possible, it might help the lives of offspring. ## Exploration/adventure Excitement. Something new, different. Unknown. Why climb the mountain? Because it's there. ## Deportation Life experience isn't always from willingness. Society chooses for us sometimes. [Answer] Convict colony: Get rid of undesireables, but without having to soil your hands by murdering them. [Answer] this sounds similar to "Mayflies" by Kevin O'Donnell. Generational ship. Time delay with communications and advancements in science. The problem they had was that, while the first generation was all gung-ho. The succeeding generations lost that drive and lost their scientific knowledge. I'm assuming that your "social engineers" can ensure that all the succeeding generations will retain the same gung-ho attitude of the original crew. Remember parents have no control over what their children want to become or what to study or whether their children want to study at all. Better plan for some redundancy for the people necessary for ship operations. Motivation for people: For the adventurers, thrill-seekers, easy sell. From your description it already sounds that earth has "little new frontiers" for these kind of people. Young military families also. Some companies might agree to send some of their researchers - drug companies to reasearch dna of plants on other planets. Or if they cant send people - then these companies might want to help with **funding** for exclusive rights to new discoveries on other planets. It will be a long term investment for them but it will be worth it. Mineral rights alone could be a fortune. Those same companies might even help with faster-than-light research since it will guarantee quicker returns on their long term investment. [Answer] ## Not the benefit to Earth The main direct benefit IMHO is not to "Earth as a concept" or a global government or the people back home. In a realistic scenario, apart of warm fuzzies of exploration, the only positive benefits occur to the actual colonies and to 'humanity' as a whole that includes both Earth and colonies. Colonists gain opportunities that would be impossible for them on Earth (and would self-select from the subpopulation that desires this tiny set of opportunities specific to space travel). Humanity becomes more resilient, especially to existential threats. But "government of Earth" ? It would gain some benefits in R&D testing and exploration, absolutely zero benefits in resources obtained, a PR effect that might be positive or negative depending on various random details, a significant cost, and some future political threats, as there are no reasonable ways to control the colonies in the future - it's essentially creating a new civilization that might become cooperative or competitive over time. There is no direct benefit to anyone staying back home - the invested resources really won't bring any returns back to Earth over their lifetimes, the expansion of the humanity won't give *them* more space (apart from the minor effect of the people leaving - which could be achieved much simpler by killing them), and the safety of humanity won't prevent *their* existential threats, rather vice versa - it would make it slightly more likely that Earth gets destroyed, and knowing that humanity lives on elsewhere probably won't make it easier for them when they go down with their planet. ## For mankind The reasons to actually do so are simple - idealistic reasons "this should be done" for the politicians and funders, and personal reasons/ambitions that cause people to do reckless things for glory. History has shown that there always is a significantly large minority of people that find those reasons suitable enough, mostly young males with no commitments (or unwanted commitments), nothing to lose and everything to gain. Going on an interstellar colonization is practically a far better prospect than volounteering and going off to a far away land to die in someone else's war, and reality shows that there are quite enough people willing to do that. [Answer] Others have given the best answers to why any humans would pay for or go on this mission, but an important consideration is whether it even succeeds. After all, your world may have the technology to spot potential farway homes, but that is not the same as colonizing them. Some worlds may be duds. Some colony ships may like space so much, the idea of landing is actually unappealing. Some might decide to camp out in the middle of nowhere, setting up a rest stop on the interstellar highway in anticipation of all the future traffic. After all, if you have a ship big enough to sustain generations of humans, you have a complete moving world all by itself. The first generation will grow weary of the confinement, but the second generation will never know the freedom of a full planet. By the third or fourth generation, the idea of living on planets may become a full-on heresy, on *all* the colony ships. This idea was lightly explored in Larry Niven's *Footfall*. ]
[Question] [ I am world building/culture building for a story that I'm writing and one of the races/sapient species is patterned after spiders. I'm willing to take a lot of liberties with the physiology (for example, structurally they resemble Trogloraptors and they have the size range of Shetland ponies), but I would like to base most of what I come up with on actual science. My question is: how would spiders that size and that intelligent communicate, not just with each other, but with other sentient peoples? Most of what I've found so far (via Google) says that spiders can't hold their breath because of the way they breathe, and so wouldn't be able to speak. I've also read about spiders hissing (not sure if that's on purpose, though) and tapping (that does seem to be intentional). At this point I'm thinking this race would use a lot of sign/body language to communicate, but I am still hoping for some sort of sounds to add as well. [Answer] [![enter image description here](https://i.stack.imgur.com/UZe4Z.jpg)](https://i.stack.imgur.com/UZe4Z.jpg) from <https://www.questacon.edu.au/outreach/programs/science-circus/activities/humming-hangers> If you wrap strings around your fingers and put them in your ears, you can hear transmitted vibrations from whatever the strings are attached to on the far side. On the web now I see all coat hangars but when I first learned about this it was with an oven rack. I have also used a chain link fence and a metal slinky. The slinky is amazing. On desiring communication, the spiders would put a taut length of web between them and communicate by plucking notes, altering the tension of the string or its length (as one would do with a guitar string using the frets) to alter the notes. Humans could hear this communication too and could learn the language. A quick one string could be for quick communications. More complex communications would require more. I can imagine there might be a chamber with an enormous many stringed web used to communicate with many individuals at once, or for communal songs. [Answer] ## Vibration is your most likely and realistic answer. Spider physiology provides very sensitive hairs on all of their legs. These hairs are extremely sensitive to vibration - this is how web-building spiders can detect prey entangled in the webs. If you have ever watched a spider catching a fly or other bug you are in for a fascinating lesson in vibration. If you toss some bugs (or small leaves or tiny pebbles) into spider webs, and watch where the spider is lying in wait, you will first see a leg or two poke out and touch or grasp the web (some spiders have small claws at the tips of their legs). They will just sit there for a while, listening or rather feeling for vibrations of struggling prey. If they feel nothing, they will actually jerk the web strands, inducing sway and vibration into the web. Then they will sit there some more listening, err, feeling the dynamic movement of the web in order to tell if something has been added. If it is really light (leaf) they will usually ignore it, unless there is a breeze, and it is flapping around against the web. If it is not so light (a bug, tiny stick or pebble), then they will venture out and take a gander at it. If it looks promising, or looks like it has damaged the web, then they will carefully approach and web it or cut it free. Oddly enough, they will web up and drink a ball of spit.... Anyway. If a spider is large enough, as yours seem to be, it would have to deal with the macro scale more than the micro scale, and it would be possible for more advanced forms of vibration sensing to come into play. For example, echolocation. Humans are (somewhat surprisingly) capable of learning echolocation, it would be rather less surprising in a biology devoted to sensing vibration. If they could send out detectable pulses, rather than a passive sense, then they could communicate using a more complex version of Morse code. Let's give a nod to *click-speak* used by Julie E. Czerneda's Ganthor (one of Esen's favorite races) and many other civilized species who lack the appropriate mouth (or other) parts necessary to produce sounds intelligible to each other. A percussive language best done with the clicking of hooves (and the occasional stamp for emphasis) which is somewhat simplistic in grammar, but more than enough for basic mercantile or mercenary exchange along with other important basics. **Music, the universal language... now featuring Spyyyyy-dar!** Personally, I really like the idea of using strands of web as string instruments and having a musical based language which was suggested elsewhere. My mind is already going Battle of the Bands where spiders use different forms of music to convey not only words and meaning, but emotions as well. Blues with a touch of hard rock for that melancholy laced with anger, and smooth jazz interspersed with some dubstep for political commentary. You know, spiders would be *really* awesome at dubstep... just visualizing it is putting my imagination into overdrive. **Taste and Smell** It is also worth mentioning that a spiders sense of taste and smell is mostly located in the legs as well. Those hairs are very sensitive and multi-function. Should they be able to scent or leave tastes upon web stands, you could have a very interesting and complex form of non-verbal, non-symbol based communication. **Telepathy, no really, hear me out here** If you are willing to get creative with biology, an RFID-like pseudo-psionic ability to communicate is also theoretically possible. It turns out that the network of blood vessels and cerebro-spinal fluid channels in the human brain actually function as a natural Faraday cage, blocking out external electromagnetic signals. It is theorized that some people, those who claim to hear voices or other signals with their brain have gaps in the natural Faraday cage, which allows external electromagnetic signals to stimulate neuron clusters, which give rise to anomalous brain activity which is interpreted by the person in question as psychic phenomena and so forth. Quantum paired particles shared between people is also another proposed possible source of this. In any case, should you be willing to get creative with biology, then a species of creatures with natural gaps in the sheathing around the brain, may actually be able to exchange recognizable signals between pairs of creatures who are close enough (about the range of an RFID tag), especially if they have developed actual signal transmitting organs. Along with this idea, I should like to mention the excellent light novel *Mother of Learning*, which has some GIFTS as major characters in the story (Giant Intelligent Friendly Talking Spiders) who use more traditional psionics ala telepathy to communicate with those few humans capable of doing so. They have some interesting insights into what sentient spiders would be like, so worth a reference. **Visual communication** Web spinning sentients may also devise a written form of communication using their built in means: webs. A spider holding up a Cat's Cradle between it's forelegs may indicate a desire to talk, or perhaps a merchant with some interesting wares (pickled giant flies, anyone, fresh from the vat!) And let us not forget Arthur C. Clark's (iirc) contribution: spiders with the ability to control the colors on their skin, who "talk" via bands of color. [Answer] Well from what I know of, you could have maybe 3 options. 1. Lungs. The reason why insects are so small is because of the way that they breathe, they have small holes in their body (called tracheae) and air diffuses into these holes and then goes into their blood. As for spiders, see the following quote from the website: <http://www.explorit.org/science/spider.html> > > Spiders have lungs. There are two sorts of lungs neither of which is like a human lung. Some spiders have book lungs. A book lung has a stack of soft plates called lamellae. Oxygen in the air passing between the lamellae diffuses through the tissue into the blood. Other spiders have tracheae which are breathing tubes held open by rings of chitin. The tracheae open to the outside and the opening is called a spiracle. There appears to be no active, muscular breathing mechanism. Air seems to pass in and out of the book lung or the tracheae in a passive manner. > > > So spiders can have air holes, but can also have rudimentary lungs that do not work in the way that our lungs work. -ALSO- This type of lung would absolutely not allow speech, as there is no movement of the lung involved, and in order for humans (and other animals) to produce sounds we have to force air out of our lungs, through our voiceboxes and out into the air, which is not possible with box lungs and tracheae without some major modifications. However, if the spider was the size of a shetland pony, it would NEED efficient lungs in order to get enough oxygen into it's blood to survive. You may have heard of spiders in the long long past being huge, like size-of-your-head huge, and this was due to the incredibly high oxygen concentration in the air at the time (this also allowed other insects to be huge), but it is not the case in today's Earth (or likely where you are). So, for the most scientific answer, either make the oxygen content of the world incredibly high (making all insects huge and likely stopping the evolution of humanoids long ago), or give the spiders efficient lungs (which would evolve if spiders becoming this large was necessary). As a result of this, the spiders can have rudimentary voiceboxes, and produce and manipulate sound with their mandibles in order to produce a spider language (however it is not likely they would be able to speak English, it would sound more hissy/whistly). 2. Rick and Morty In the popular cartoon show Rick and Morty, there is an episode ("The Ricks Must Be Crazy", season 2 episode 6) where large (nearly as tall as humans when resting on all 8 legs) spiders have evolved or landed on Earth (I'm not too sure which) and communicate by telepathy. There is no scientific grounding for this, but it would be an interesting one to explain, if I get the time I may try and think of something but for now, it isn't possible. 3. The fun one. An idea I just had, and would be very interesting to have - with some significant modifications the tracheae of modern-day spiders could potentially act like mini-lungs, here I'll explain. So a tracheae is basically a tube that goes into the body of the spider, and allows oxygen to diffuse into the blood of the spider. IF surrounding this tracheae you had muscles and expanded the tracheae (pulling air in) you could have rudimentary lungs all over it's body. Then, by using muscles to change the size and shape of the hole (the spiracle), it could potentially produce a sound. Now, this is not a current evolution that spiders have, but if you have a spider the size of a small horse, there's either millions of years of evolution or they're aliens so pretty much anything is on the table. This would give the effect of the whole body 'speaking' however it certainly wouldn't be a language even remotely close to English, it would sound closer to a humming or whistling coming out of it's whole body. There are obviously more things you could do, but here are my 3 ideas, if I think of anything else I'll add it. Also, you would need ears - just so you know. Hopfully it was useful! [Answer] # By rapidly changing colour patterns Many spiders have [chromataphores](https://en.wikipedia.org/wiki/Chromatophore) that enable them to change their pigmentation on demand, e.g. for [camouflage while hunting](http://www.dailymail.co.uk/sciencetech/article-3029441/Bad-news-arachnophobes-Scientists-reveal-whitebanded-crab-spider-change-COLOUR-hunting.html). Other species that have this ability [have been known to use it for communication](http://www.dailymail.co.uk/sciencetech/article-3029441/Bad-news-arachnophobes-Scientists-reveal-whitebanded-crab-spider-change-COLOUR-hunting.html), so it seems reasonable that a more intelligent species may refine it to a complete system of communication, perhaps along with an evolutionary process that allows them better control due to beneficial improvements in communication improving their fitness (do your spiders hunt in groups, perhaps?). [Answer] **Vibration patterns and silk markings**. Spiders use listening strings to know that prey has been captured. Even our spiders are smart enough to discern if wind has moved the net or if real prey is fighting for its life. So intelligent spiders will have strings where visitors will introduce themselves by their vibration pattern and they will have perhaps delicate patterns inside their nets which visitors can use to talk publicly or with a specific neighbor. Spiders are also known to have many different kind of webs. So they will be able to create messages themselves and leave them as signs or markings. [Answer] EB White covered this topic extensively and the subject of Zuckerman's famous pig in his book Charlotte's Web. A spider hoping to save the life of a pig named Wilbur, convinces a rat named Templeton to bring words and phrases she could add to her web in hopes of sending messages to the Zuckerman family to not eat Wilbur the pig. The spider demonstrated reason by rejecting words like "crunchy". It's a series of stories for children, but it does show some forethought to what behaviors a talking orb weaver, most likely a European Garden Spider, would exhibit in their attempts to communicate with other species. <https://en.wikipedia.org/wiki/Charlotte%27s_Web> **Why I am I posting a children's story? Do I want to get downvoted?** No, but spiders use two forms of communication, vibration and webs. They use silk to line burrows, build trap doors, build pathways, collect insects, attract mates, fly (seriously) and they use vibrations to send signals. Charlotte's Web is a very popular series of stories and I think it would be worthy of noting when attempting to figure out how spiders communicate because it's going to be in the back of people's minds when reading stories about giant spiders and their ability to communicate. [![Charlotte`s Web](https://i.stack.imgur.com/BwMwU.jpg)](https://i.stack.imgur.com/BwMwU.jpg) [![Humble](https://i.stack.imgur.com/wY4y2.gif)](https://i.stack.imgur.com/wY4y2.gif) [Answer] Spiders exchange gases using [book lungs](https://en.wikipedia.org/wiki/Book_lung), which mostly don't move; they don't have lung-like large bags of air that can pump breath through a vocal apparatus, so *if* your spider aliens are like Earth spiders in this regard, they shouldn't be able to speak (or hiss, or scream, etc.): they can't hold their breath and they cannot modulate it. From what I've read, the "hissing" some spiders do produce is actually made by the friction of their body hair. Spiders' principal eyes can form rather accurate images (and in some spiders they actually have the ability to zoom in and out), so visual communication should not be a problem if you decide to go that way. But if you ask me, communication based on detecting vibrations is the way to go. Speech sounds are of course vibrations traveling through air, but spiders don't have ears and I'm not sure how sensitive they are to human speech sounds (or the like). They are, however, extremely sensitive to vibrations such as those transmitted by solid, elastic materials. Tapping the ground or the nearest wall should work with a spider-like alien, as well as employing low-frequency airborne sounds. [Answer] If you're willing to "take a lot of liberties with the physiology", then give them all the equipment (lungs, trachea, larynx, pharynx a tongue and dexterous lips) needed to speak. And ears to hear with. [Answer] **Sign Language** With their eight limbs a spider would have no problem using 2+ at a time to perform very complex signs or semaphore while still holding onto a web or standing/sitting on the ground. [Answer] If they are intelligent, they could write on keyboards, or just like Stephen Hawking, we could make some kind of tool to work as gesture-to-speech. In my personal opinion, though, I'd communicate with them would be with a 10-foot pole and lots of fire. ]
[Question] [ First question! I'm excited to see if anyone can help me. Any missteps are unintentional, but feel free to tell me so that I may learn. --- So, I've recently started brainstorming over a possible story, and I was wondering if someone might be able to lend me a hand with a bit of worldbuilding. The world where the story takes place is a classic high-fantasy setting. However, there is a sci-fi element to it that is giving me some trouble. Imagine an alien spaceship that crashes on the high-fantasy planet. Imagine that the people who live on said high-fantasy planet eventually scavenge the spaceship and find out that the alien metal is great for forging magical items of all kinds. Now, imagine this metal glows a pale blue when pieces of itself are near each other. I could chalk it up to magic and be done with it, but seeing how this is a plot device wrought from sci-fi elements, I would like to have a more or less science-based answer for why the metal reacts to itself. The way I thought about it, the starship itself doesn't glow when it's in one piece, but after being dismantled, its largest chunk begins glowing and doesn't stop glowing, sort of like a beacon for all its smaller pieces, which in turn glow brighter the closer they get to a larger chunk. Chunks of roughly the same size have a faint glow that is sort of noticeable in the dark. Larger chunks have a greater reach, making smaller chunks glow from many metres or even kilometres away. I'm willing to edit these details to better accommodate your answers. I've considered some sort of nanotechnology being responsible rather than the glow being a naturally-occurring phenomenon—it's an alien artefact from a spacefaring species, after all. I've also looked into bioluminescence and incandescence and pyrophoric properties, but nothing quite hits the mark. If what I'm asking is at all possible, please do tell! --- **EDIT1:** The sci-fi explanation will be required further down the line for the plot, which is why I'm trying to figure it out. People from the high-fantasy world will consider the metal's glowing to be magical in nature until then. **EDIT2:** It doesn't have to be metal! It can be any material that can be turned into the usual items you see in fantasy worlds—weapons, armours, cooking utensils, amulets, light fixtures, clockwork mechanisms, fancy furniture, and the like. **EDIT3:** I would rather not have the metal be sentient. [Answer] **A Programmed Feature:** This idea is inspired by Willk's answer, though there have been other good ideas in the thread. It's a deliberate design choice by the long ago designers of the craft. Meant to help highlight and locate damaged components - the nanites activate a phosphorescent effect whenever chunks of the ship become separated from each other. This affect is particularly activated via damage or forcible removal. The actual creators had the use-permissions or password to remove components without triggering the location beacon effect. The glow could even be a side-effect - the main signal is a low radio pulse or particular radiation signature that is easier to track - However the high-fantasy locals don't have the technology to detect or track it, so the glow is all they see. For power source - the nanites could be accessing solar power, or any inbuilt power sources of the components themselves. Maybe the nanites are set up to harness multiple different sources of energy, but they'll slowly fade away if there's nothing suitable. [Answer] See someone has already answered with nuclear decay... My answer is not actually based on science, so I know my answer will not be popular. This is more based on junk science and sci-fi concepts that we haven't yet mastered or even come close to. Quantum entanglement/FTL communication is the best I've come up with, and that's more sci-fi than regular science. There also might be a way to sci-fi the principle of magnetism and magnetic fields. Unfortunately, actual science doesn't have much that works this way. EXCEPT in ways that can't be seen. What you're looking for is a way that the same element can "activate" its twin. The best example of that, though it isn't visual, is magnetism. When something is magnetic it creates an invisible field--two magnets will either be repelled or attracted depending on which side of the magnet is up against the other. Here's a [handy link on how it actually works](https://www.ece.neu.edu/fac-ece/nian/mom/work.html). My point is that your unknown element might work on some of the same principles--that of attraction and that two chunks of it might create something like or akin to a magnetic field. There will be differences, of course, but in this case, the field created is more dramatic and visual. There might be something within the metal that is "drawn to the surface" when another of its type is there nearby. This means that it's going to be unlike ANYTHING on earth... My other, sort of left-field theory is: there was an experiment and large amounts of this metal was created and quantum entangled and/or has quantum non-locality. From wikipedia: > > Quantum entanglement is a physical phenomenon that occurs when pairs > or groups of particles are generated, interact, or share spatial > proximity in ways such that the quantum state of each particle cannot > be described independently of the state of the others, even when the > particles are separated by a large distance > > > But this means that one molecule of the stuff next to another would ALREADY be glowing. I would make this metal a component of Faster-than-light communication. Something impossible that we have not yet done. Here are the three ways that wiki says that this could happen: > > Proposed mechanisms Tachyons Tachyonic particles are hypothetical > particles that travel faster than light. These would allow > superluminal communication, and for this reason are widely believed > not to exist.[2] By contrast, tachyonic fields - quantum fields with > imaginary mass - certainly do exist, and exhibit superluminal group > velocity under some circumstances. However, such fields have luminal > signal velocity and do not allow superluminal communication.[3] > > > Quantum nonlocality Quantum mechanics is non-local in the sense that > distant systems can be entangled. Entangled states lead to > correlations in the results of otherwise random measurements, even > when the measurements are made nearly simultaneously and at far > distant points. The impossibility of superluminal communication led > Einstein, Podolsky, and Rosen to propose that quantum mechanics must > be incomplete (see EPR paradox). > > > However, it is now well understood that quantum entanglement does not > allow any influence or information to propagate superluminally. > Technically, the microscopic causality postulate of axiomatic quantum > field theory implies the impossibility of superluminal communication > using any phenomena whose behavior can be described by orthodox > quantum field theory.[4] A special case of this is the > no-communication theorem, which prevents communication using the > quantum entanglement of a composite system shared between two > spacelike-separated observers. Some authors have argued that using the > no-communication theorem to deduce the impossibility of superluminal > communication is circular, since the no-communication theorem assumes > that the system is composite.[5] > > > Wormholes If wormholes are possible, then ordinary subluminal methods > of communication could be sent through them to achieve superluminal > transmission speeds. Considering the immense energy that current > theories suggest would be required to open a wormhole large enough to > pass spacecraft through, it may be that only atomic-scale wormholes > would be practical to build, limiting their use solely to information > transmission. Some hypotheses of wormhole formation would prevent them > from ever becoming "timeholes", allowing superluminal communication > without the additional complication of allowing communication with the > past. > > > So basically, as a result of "active tachyons" or smaller than microscopic wormholes or whatever, whenever non-physically linked chunks of the stuff get close to each other, they "communicate." I would think that they glow all the time, but that they glow more when they near each other, which is something that perhaps might have been used as part of the communication system somehow. [Answer] ## Electroluminescence Short answer, the metal/alloy produces a high frequency low current EM field, and the voltage increases with more in proximity. The oxide layer produced by exposure to the atmosphere acts as an inorganic electroluminescent phosphor. The metal would be able to make other electroluminescent items glow as well. Long answer... Electroluminescence works when electrons move between energy bands, gaining energy by electricity, losing it by emitting photons. The material properties determine the wavelength of the photon and its color. Typical inorganic metal phosphors are made of zinc sulfide and doped with something such as copper or silver, giving it a green (copper doping) or blue (silver doping) glow (like a Timex watch Indiglo backlight) [![enter image description here](https://i.stack.imgur.com/UU3ke.gif)](https://i.stack.imgur.com/UU3ke.gif) The electricity generally comes from an AC source, or from a DC to AC converter, but can also be provided by EM fields in proximity, [take a fluorescent lightbulb underneath an electrical pylon for a good example](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Fluorescent_tube_under_electric_line.jpg/512px-Fluorescent_tube_under_electric_line.jpg). In this case, we can generate an electrical field by the metal interacting with the EM field of the planet. The metal alloy is designed to do this, it is part of the deflector system for FTL travel, a super high strength EM field aboard the ship generates an electrical field on the hull, deflecting ionized particles before they impact. In space there is no oxygen, and the outside of the ship does not glow, but the inside does, providing a light source for the crew by having all exposed and oxidized metal glow, with the specific alloy composition providing the desired color (blue-green is easy to see in the dark). I believe this is the least "handwavy" answer, as the concepts are rooted in real science that is used right now in consumer applications, and it does not involve harmful ionizing radiation. The downside is that it MUST produce electroluminescence in other items containing a similar phosphor, probably more so that the metal itself. That is because the voltages energies involved in space would be very high, and the glow will be blindingly bright if the oxide phosphor was very efficient, whereas efficient phosphors like zinc sulfide require almost no energy to glow, but high voltage. Since you are only dealing with small metal pieces like amulets, they would not glow by themselves, but could make normal phosphors glow in proximity. When you have a lot of metal gathered, the metal glows, and other phosphors will glow brightly, even at a distance of several feet. Possible additional property, the metal fragments would glow by themselves during geomagnetic storms and solar flares, like the Aurora Borealis, or in the presence of high strength artificial EM fields. Image of watch By [Andrew J.Kurbiko](https://commons.wikimedia.org/w/index.php?curid=40779945) - Own work, CC BY-SA 4.0 [Answer] **It is alive. The pieces are calling to each other.** > > its largest chunk begins glowing and doesn't stop glowing, sort of > like a beacon for all its smaller pieces, which in turn glow brighter > the closer they get to a larger chunk. > > > These things want to be together. They are distressed to be apart. They are glowing because they are calling to each other. The big one is like a chicken calling to its chicks - it has the loudest call. The chicks want to be together too but what they really want is to get back to the chicken. Maybe in their native habitat these things have a way to act on the glow and move closer together. Or maybe they will move, under the right circumstance. They must be capable of perception if a glow can be a beacon. The glow might include radiation wavelengths not visible to humans. [Answer] My answer is based on a previous answer which is about radiation. In my opinion that's exactly what you need. I thougth of [Tritium](https://en.wikipedia.org/wiki/Tritium) which is usually used in watches to power the flourescent glow of the device. The problem is Tritium does not glow, it needs additional fluorescent material to do it, nor is it a metal. So I come up with two ideas: 1. Should your alien matter be metal at all? Maybe a polymer compound could also be good, and since tritium is an isotope of hydrogen it could easily be attached to any organic molecule. And there are also [organic glowing compounds](https://www.sciencedaily.com/releases/2017/10/171002112802.htm), so a combination of the two is more than likely to be possible. 2. [Europium](https://en.wikipedia.org/wiki/Europium) is a type of glowing metal, but it is not very metal-like, it > > can be dented with a finger nail and easily cut with a knife > > > Moreover it rapidly oxidizes in air, so I would recommend your metal to be an europium-based alloy with some other metal that could prevent the oxidization (possibly chromium - I do not know whether its viable or not to alloy it with chrome, but a spacefaring race might figure out how to do it). And the magic would be to have hydrogen, or in our case tritium, diffused into the alloy. Hydrogen in metal alloys is not uncommon, read more about it [here](https://en.wikipedia.org/wiki/Hydrogen_embrittlement). This would introduce radiation, so fuel for the glowing, and would make the alloy harder (that is what hydrogen usually does with steel, also makes it brittle though). Assuming this sentence from the answer of Cort Ammon: > > Now its also known that many radioactive materials emit more radiation when brought into larger masses (I think all such materials do, but I'm not positive). > > > (which I also cannot prove nor disprove) we have a radiating, glowing metal alloy with the needed characteristics. You might feel there are loads of ifs and maybes here, but in my opinion these two could be acceptable solutions to your problem. These would work of course only at night, because of the small amount of emitted light. Oh and the spaceship should not glow - I recommend it to be painted. (Sometimes the easier solution is the better.) [Answer] This sounds like Newtonian gravity, but restricted to this metal ‐ and not all the matter in the universe‐ and with *glowing* replacing *acceleration*. > > ...doesn't glow when it's in one piece > > > Just like one piece of matter doesn't accelerates itself. > > ..its smaller pieces, which in turn glow brighter the closer they get to a larger chunk. > > > Just like [force is inversely proportional to distance](https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation)... > > Larger chunks have a greater reach. > > > ...and [directly proportional to mass](https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation). [Answer] Just an idea for you to build off, or anyone else with more science knowledge. - A play off magnetic material - as magnets do seem to call to each other, but not visibly. But suppose you have a special alien space alloy, this alloy is composed with a super rare-earth magnet type material. The stronger this special magnetic field the more the components glow. Dust sized particles don't have any glow-magnetic property as their mass is insufficient to cause the glow-magnet field. Particles need to be within some exponential/logarithmic range (depending on which way you're calculating) of other particles to glow. For a "large" particle to glow there must be other particles within a certain size category and proximity to create the glow-magnetic field. Likewise for "small" particles to glow, they must be in range of particles sufficiently large or close to glow. When fused together, there is no glow because the field is self contained. So then your spaceship might glow while whole if "near" other space ships of similar design and size or within a greater distance but still sufficiently near a "mother-ship". Opposing alloys (enemy vessels) would glow a different color when brought within certain proximity to friendly vessels. (Red fleet versus blue fleet.) But when a scout vessel is lost in space, and crash lands on a remote planet, it is outside the "glow-field" of it's allies (and hopefully its enemies). So until it breaks apart it doesn't glow. Once broken apart it creates its own "glow-field" . So if the ship broke up in atmosphere, then the largest chunk would be sufficiently large to create a glow field that covers "x" portion of the planet. Other large chunks glow because they are in sufficient proximity to the "Alpha" chunk. Smaller chunks may glow because of the proximity to "Beta" chunks. The intensity of the glow would be based on the proximity of the "larger" chunk and the size (or relative size) of the larger chunk. Though, also possible that a chunk of one ounce may respond to a chunk that's one pound, but not to a chunk that's ten thousand tons due to the field of that larger being overwhelming. (For this the glow feature must be a mutual energy field and if the size variance is too great there isn't sufficient energy received from the smaller particle to facilitate glow - or that it's in the great field of the "Alpha" particle - akin to compasses being pulled to a rod of iron when within a few inches, but despite the mass deferential not being impacted beyond a certain range because the earth's iron core mass and relative proximity overrides the local mass at its relative proximity) For forging into weapons and armor, you make the alloy one that is pliable under heat at regular forging temperatures and pressure (so heat and strike, but heat alone is insufficient cause then re-entry would be problematic ....but you could have special drop ships that were intended for re-entry and these stellar ships were never meant to be in the atmosphere...) But the alloy itself remains intact despite pliability unless some other criteria is met (higher heat, an electric arc while forging, etc or even a special "un-quenching" process that unlocks the alloy's particles). Thus, the pliable alloy can mold to other metals like steel or gold, but not actually bond with it, thereby fully retaining its specially properties. [Answer] **Have a look at Metamaterials** [Metamaterials](https://en.wikipedia.org/wiki/Metamaterial) are manufactured materials that have properties that natural materials do not have. Research into Metamaterials has been continuing for some time, and there are discussions that these materials would become more and more common in the near future as they approach viability, with some already in use today. They are actually combinations of materials, incorporating anything that may be needed for its usefulness and usually based on modular / repeatable elements. The basic premise in regards to your question is to create a Metamaterial that: * detects proximity to other materials * retains a form of electrical charge * illuminates given certain conditions It is easily conceivable that a space-faring race would have advanced technology in terms of materials too. [Answer] I don't think there is a true science answer for this. Materials don't behave this way. If this were in a large field, perhaps separated pieces would behave differently than the pieces merged. Consider metal in a microwave oven. Small pieces will spark and melt because the currents are too high. A large piece, like a metal bowl, will be fine with no sparking. But, there is no such field that permeates our space. You could imagine that the ship is built out of billions of independently knowledgable components and that the "glow" is tiny thrusters on each component trying to place it back in the "ship" configuration. The material would be tough to use for other purposes if whenever you forge it into something useful, it turns back into hull plating when you aren't looking. [Answer] You can build an effect like this by invoking a sort of augmented magnetism. Suppose there is some force that pulls on some particles in the material, and pushes on other particles in the materials so that the net effect is that there is not overall force between the two bulks of material, but microscopically, you are getting motion of the molecules. Now suppose when a molecule moves fast enough, it spontaneously emits some light and then switches from the type of molecule that is repelled to the type that is attracted, and visa versa, keeping the total number of repelled and attracted particles in balance. This whole processes will end with an equilibrium where all the molecules are moving slowly enough in the material so that no light is emitted (which is why you can have one bulk of the material that doesn't glow). However, you can choose how long it takes to reach that equilibrium without breaking the scientific plausibility of the scheme. If larger chunks are brought together, then there is more force on the particles and thus more light is emitted. Again, you can choose to say it takes 100 years for the material to come to equilibrium, so the glowing can be constant (and breaking a chunk of material off of a bigger chunk will cause the two to glow for a long time). Or you can say it only takes a few seconds so that you have to be moving the chunks around in order to get the glowing effect. Basically, this scheme is general enough that you can get almost any behavior. The fundamental idea is that you need to have forces on the particles that cancel out, because otherwise the chunks will be forced together. And you need to have some sort of decay that is tied to the strength of the forces between particles in order to create light that grows stronger when the chunks are brought together. Two more points: 1. The reason I said let the particles change from the repelled to the attracted type is only so that the material can be "pure", i.e. made of the same molecule that sometimes attracts itself and sometimes repels itself. 2. In order to conserve energy, you should have the material slowly waste away. The rate this occurs can be so slow that you almost never see it in practice. There are some technical details about energy conservation that an astute observer might have a problem with, but those could be explained with some more leg-work. [Answer] What you have here, is a metal with an unstable outer shell of electrons. At the slightest provocation, an electron may jump to a higher orbit, quickly lose energy, and return to its normal orbit. These fluctuations cause the metal to emit a field, and the effect compounds: The more metal you have, the wider the field around it. If another piece of this same metal enters that field, it can cause all the electrons in the outer shell to fluctuate at once, emitting photons of visible light, causing it to glow. The reason that a single large piece of metal doesn't react with itself is due to polarization. When the metal is melted down and reformed, all the atoms align in a mesh, causing the additive field effect. The bits of metal can even find each other, a bit like a magnet. If you have one, and it begins glowing, you can turn it in all directions until the glow dissipates. This tells you that the two pieces of metal are polarized and therefore lined up. Last but not least, it is possible for other forms of radiation to cause the sword to glow. Magical objects, or even inherently magical creatures **may** give off some sort of field causing this metal to glow, though there may be differences in the glow itself, or the shape of the metal may contribute to its reception. [Answer] The material 1) needs to either contain a huge amount of energy or somehow continuously harvest energy to glow, and 2) needs to radiate and be sensitive to the same radiation to sense nearby pieces. My idea is that the material harvests vacuum energy and turns it into microwaves. Further, if the material is externally irradiated with microwaves it produces visible light. Call it, say, a "(meta)material that taps the Dirac sea using Casimir oscillators and is photoluminescent". When the ship was whole, the structure of the ship acted as waveguides for the microwaves, funneling them to a surface at the rear of the ship that was irradiated and thus glowed intensely, producing photon thrust. Small structure changes could change which surface on the ship produces thrust for steering and control. When the ship broke apart the radiation no longer had a waveguide and would simply cause any nearby pieces to glow. Now, if I actually understood the theory behind the casimir effect or microwave engineering I could probably immediately point out flaws in this, but hey, that's what the comments are for. [Answer] Kinda coming off other ideas, here. What if, the material constantly outputs a high frequency wave, i.e ultra violet, And that the metal will glow when subjected to the right frequency (materials that do one or the other exist IRL.) Then, when brought near eachother, the air filtering them slightly changes the frequency, and when at the right distance, will be good enough for them to glow? If too far away, it would only glow dimly, but the same would happen if too close. ]
[Question] [ Around 100 million years ago, the Solar System was instantaneously encased in a massless, magical sphere centered about the Sun. The boundary is about 10,000 AU (.158 ly) in radius and behaves abnormally: matter and energy from outside the boundary may enter into the Solar System unaffected, while matter and energy trying to exit is essentially erased (if you were to reach your hand beyond the boundary, you'd retract a gory stump). Question: Assuming that everything else proceeded as usual with the dinosaurs' extinction and humanity's uprising... **With such a structure just thrown up like that in the distant past, could there be any astronomically glaring signs or repercussions of it that would tip us (present-day "modern" astronomers with our space telescopes and space probes) off to its existence?** I am searching for any consequential phenomena that results from the boundary's introduction that also signals to modern astronomers that something is at least *not right* with outer space at that distance (keep in mind, the alien sphere itself is massless, essentially transparent, and not a blackbody (matter and energy erased is not absorbed and re-emitted)). I feel like this question is better posed under the yes-or-no format. So, if the side-effects of such an alien boundary are too little for modern (can be any era up to modern, really) astronomers to detect, or there are no side-effects, then showing that with a science-based analysis constitutes a "no" answer. Showing that some form of resultant phenomena exists that also falls under astronomers' threshold of detection constitutes a "yes" answer. --- **Potential pointers**: (These are just some things I've contemplated during my research.) Of course, astronomers won't be able to see the boundary directly, as light from the outside simply passes through it unaffected in any way, though, they may be able to infer its existence somehow. Not many striking things seem to orbit 10,000 AU from the Sun. The farthest object we've currently discovered, [Farout](https://www.space.com/42755-farout-farthest-solar-system-object-discovery.html), orbits about 120 AU out. The [Oort Cloud](https://en.wikipedia.org/wiki/Oort_cloud), however, is a different story. The Oort Cloud is a hypothetical structure which defines the Sun's cosmographical Hill sphere, the region within which objects have the potential to orbit the Sun. Its radius ranges from 2,000 to 200,000 AU, so the alien boundary would have intersected and partitioned it. 100 million years is quite a few Earth-orbits, even for those super-distant objects with multi-thousand-year years, so perhaps modern astronomers would see a deficit of long-period comets with aphelia greater than 10,000 AU. (Perhaps a detectable discrepancy?) [Scholz's Star](https://en.wikipedia.org/wiki/Scholz%27s_Star#Solar_System_flyby), WISE designation **WISE 0720−0846**, is a red dwarf that has been modeled to have passed through the Oort Cloud of the Solar System at a distance of around 52,000 AU, around 70,000 years ago. Similarly, [Gliese 710](https://en.wikipedia.org/wiki/Gliese_710#Computing_and_details_of_the_closest_approach) or **HIP 89825** is predicted to have a close approach with the Sun at a distance as near as 13,300 AU (just outside the alien boundary) within the next 15 million years. The Wiki's source states that there is a 1 in 10,000 chance that the star penetrates less than 1,000 AU, significantly perturbing Kuiper belt objects. According to [this paper](https://iopscience.iop.org/article/10.1088/2041-8205/800/1/L17/meta), stellar approaches closer than around 50,000 AU happen about every 9 million years, with probabilities of even closer approaches. Exoasteroids and exocomets, such as ['Oumuamua](https://en.wikipedia.org/wiki/%CA%BBOumuamua), will have entered the Solar System, though, in the ~1,800 years it will take to reach the boundary (1.496e+12 km / 26.3 km-per-sec / 60 seconds-per-min / 60 minutes-per-hour / 24 hours-per-day / 365.25 days-per-year = 1,802 years), we won't see it or others like it leave. (We may, however, see captured exosolar bodies.) Any future endeavors to send probes or spacecraft to other star systems, like [Breakthrough Starshot](https://en.wikipedia.org/wiki/Breakthrough_Starshot) or [Project Daedalus](https://en.wikipedia.org/wiki/Project_Daedalus), will not work because they simply cannot penetrate the boundary, so, after the first few of these attempts, we will begin to at least suspect something. --- **Physical & Quantum mechanical aspects of matter-boundary interaction**: The alien boundary has 1-dimensional thickness and is mathematically smooth. It is massless. Its mathematical center is fixated on the exact gravitational barycenter of all the matter within it. Gravitational propagation is allowed through the barrier (though the boundary is unaffected by external gravitation), though not out of it. Because of this, the Solar System continues its orbit about the Milky Way (with the distinction that the Sun and all Solar System matter does not influence the galactic barycenter) and as mentioned the boundary tracks the exact barycenter within. Quantum tunneling to exit the boundary is impossible. Quantum tunneling *in* is okay. Entangled particles entering remain entangled to their counterparts, even if exterior to the boundary. Atoms and molecules are shaved off at the quark level and the boundary interacts only with particles that interact with it. (One can asymptomatically approach the boundary, but not cross it.) (Particles cannot move at more than a Planck length in a Planck time.) For instance, a molecule of diatomic oxygen trying to exit: electrons in the electron cloud are first to go, they are known with exact certainty; then, as the atom travels farther, the intermittent quarks and mediating gluons within the nucleus' protons and neutrons are done away with (the traversing atom would become unstable and nuclear forces would dominate it); after the first electrons vanish, the chemical covalent bond is broken (if there is excess energy in the other atom, it may be released Solar System-ward); the process continues for the next atom of oxygen, should it continue to maintain the velocity needed to cross the boundary. No energy from the destruction of particles themselves is released (the particles are not converted to energy that is released). It is a similar story for photons and all other irreducible particles. The clean and instantaneous deletion of matter would result in gravitational waves. [Answer] The local interstellar cloud (LIC) has a temperature of 7000 K and density of 0.3 atoms/cc. RMS velocity is thus $V\_{rms} = \frac{3RT}{M}^\frac{1}{2}$, or 13 km/s, for Hydrogen. At 0.3 atoms/cm^3 we have about 4 billion atoms crossing each cm^2 of the barrier every second (in each direction). Most of the atoms are hydrogen atoms. Outgoing hydrogen atoms experience a moment when the proton is torn apart; one of the quarks is destroyed, while the others remain. As 99%+ of the mass of a hydrogen atom is in its binding energy, and the two remaining quarks are no longer chromatically balanced, this will generate an insanely powerful explosion (at microscopic scales) as they jet apart trying to ground themselves chromatically. Atoms entering will also experience this, as once one quark crosses the gluon exchange with the quarks outside no longer occurs. Both the inner and outer quarks will go haywire, trying to chromatically ground themselves and finding no partners. This process will occur much, much faster than the quarks cross the barrier; the energy scales of the hydrogen moving at 13 km/s are insanely lower than the energy scales binding the nucleus together. While high energy density, the total energy will also scale with the thinness of the interstellar medium. Each hydrogen atom weighs $1.67 x 10^{-27} kg$. 9 billion of these has a weight of about $10^{-17} kg$, which when converted to energy is about 0.9 J. So the barrier emits on the order of 1 J per second per cm^2. This surface has a temperature of 374 C or 647 K. Far hotter than the CMB cosmic microwave background radiation. Now, emissions scale with the 4th power of temperature. Solving for 1K (where it might be cold enough not to be noticed?) we get 5 \* 10^-12 W/cm^2; you'd have to avoid all but 1 part in 10^12 of this proton disintegration from emitting energy. The basic problem is that discontinuities are explosive in physics. It probably will even be worse than this, because Hawking radiation scales with the sharpness of the event horizon; your event horizon is infinitely sharp, so you'll probably get something at least approximeting infinite energy emission from the surface. But that math is harder, while quark binding energy math is easy, and sufficient to make the barrier really obvious. This also neglects that almost certainly lower-order contribution of destroying the electron first. An atom is electrically neutral; destroying the electron first makes it positive, then the proton goes and it is negative. In the period between the first and second, you have a changing electromagnetic field. Such changes are experienced as photons. The frequency of said photons will be distributed based on the time difference between the electron and proton being destroyed, aka 5.29177 x 10^-11 meters. Photons of that wavelength are called gamma rays. [Answer] Yes. Astronomers could see the barrier directly because the barrier would emit Hawking radiation. Pairs of particles and antiparticles are constantly appearing and disappearing all over the place throughout space. This is called quantum fluctuation. It's usually hard to detect quantum fluctuation because the particle pairs annihilate each other soon after forming. If one of them is is removed by, say, falling into a black hole or getting annihilated by your barrier, and the sister particle doesn't get annihilated then the sister particle gets to do something else like becoming visible to astronomers. In the case of black holes these escaping particles are called Hawking radiation. [Answer] You'll have a statistical bias in orbital shapes and properties. Any comets or other bodies which are gravitationally trapped by Sol and which cross the barrier 'going out' will vanish. Overall distributions of body energies will be skewed even for bodies that do not ever enter the inner system. . Bodies which travel into the inner system and out to near the barrier will have a sharp limit to their energies. We may not currently analyse comet energies (or may) but a sharp truncation of the tail is an effect waiting to be noticed. Jupiter may "save" you. Peturbation of cometary orbits by Jupiter is significant and while the skew in a known orbit can be measured, it may be that the magnitude of the Jupiter effect is such that it swamps the statistical variations caused by the 'cosmic vacuum cleaner'. Page 274 on in the [**book preview**](https://books.google.co.nz/books?id=cW7FCwAAQBAJ&pg=PA276&lpg=PA276&dq=comet+energy+distributions&source=bl&ots=x8Mo1xOHwh&sig=ACfU3U0ltJezYyLGcLiqPDziEiFbAmWPZw&hl=en&sa=X&ved=2ahUKEwjv8NDkyf3gAhUdi3AKHYojDo8Q6AEwCXoECCIQAQ#v=onepage&q=comet%20energy%20distributions&f=false) of "From Ordered To Chaotic Motion In Celestial Mechanics" may be useful. **\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **The 'shell' already exists** A "cometary fading effect" that operates much as you have described already exists. While 'we' have detected it, the mechanism is unknowm. See section 2.3 of this [**book preview**](https://books.google.co.nz/books?id=AHF9ZraafV8C&pg=PA160&lpg=PA160&dq=comet+energy+distributions&source=bl&ots=Jt5b1iys3Q&sig=ACfU3U0QRoCXfN5vqs327Pm4yiscaHYZgA&hl=en&sa=X&ved=2ahUKEwjv8NDkyf3gAhUdi3AKHYojDo8Q6AEwCnoECBoQAQ#v=onepage&q=comet%20energy%20distributions&f=false) from "Comets II". Next question please. [Answer] The shield would act as a vacuum cleaner as the solar system moves through space (both in orbit around the galactic center and as the galaxy itself moves). Any interstellar dust would enter the shield but be erased on exit, which should leave detectable disturbance as we would leave a void in our wake that would slowly be refilled by surrounding dust. The void and the dust itself would not be visible so much as its affect on any light approaching from behind. [Answer] # Possibly, but far from certain The proposed distance to the barrier - 10,000 AU dissects right through the Oort cloud. Currently, the detected object with most distant orbit around the Sun is "[The Goblin](https://en.wikipedia.org/wiki/2015_TG387)", with the aphelion of 1955 AU, which is well short of 10,000. This means that we are not ready yet to see periodic objects which travel that far from the Sun. Maybe in another 10-20 years we'll see something with aphelion over 10,000 AU, but we haven't seen anything like that yet. However, during the lifetime of the barrier (100 million years), Oort cloud would be depleted. This means that inner solar system would see a gradual decline in long period comets during that period. The Earth, Moon and other planetary bodies would be bombarded somewhat less. How much less and whether astronomers would be able to actually measure this decline, is difficult to tell. Oort cloud is not the only source of comets, and inner part of the cloud (close than 10,000 AU) would still be unperturbed. P.S. "The Goblin" is potentially the most distant object that is a minor planet (with supposedly stable orbit), but not the most distant among all objects (particularly comets). A few of the [near-parabolic comets](https://en.wikipedia.org/wiki/List_of_near-parabolic_comets) apparently travel beyond the 10,000 AU limit, with semimajor axes as high as a whopping 446485 AU. So, today's astronomers **DO** have a way to detect this limit. However, the caveat here is that we don't know if those comets' orbits are stable. They may be on the very first rotation that comes close to the Sun, and once they go beyond 10,000 AU, they might disappear forever. [Answer] I would argue that the answer to you question about whether or not we would be able to detect it is no. Obviously, such a device violates the laws of thermodynamics. Firstly, you have a conservation of energy problem. Any energy or matter simply vanishing or being destroyed violates this. There are two ways I can think of that being solved for it to not violate this: 1. The structure heats up with the equivalent amount of energy 2. Material is teleported elsewhere. The first one would likely result in detection. It would give off radiation if the structure heats up. If it were to radiate inwards, Earth would likely see some very strange signals coming in that wouldn't fit with astronomical models. That being said, it kind of depends on the temperature and emissivity of the structure because it could end up being lower energy than the astronomical "noise" so to speak (see Cosmic microwave background). If it were much hotter than this though, there would be an inconsistent amount of energy when compared with the expected star spectrum and would show up as a spike in energy density of the correlating emission spectrum across all stars. For the second case, this would absolutely result in a gravitational lensing effect that at best would show up some chromatic aberration resulting in different wavelengths hitting your camera differently. All of the images taken off objects outside of the solar system would be different in terms of colors lining up to objects inside. However, I'm guessing these scenarios aren't what you have in mind. Based on your question and responses, it seems as though we should assume an ideal situation where by some effectively magic makes it work. Here, the issue is that the device would violate almost every conceivable law of physics, without producing a trace short of being very close to the device and watching something approach it. As far as I'm aware, there is no way that we can currently see an object with that precision from Earth. Any probe sent through would suddenly just stop sending signals. This would mean that the assumption would have to be from scientists that stuff just broke. Over a long period of time, eventually you would build up a case that there is something out there because your probes always fail at about the same distance but that could take at least 5-10 deep space probes. As far as I'm aware, there are only three probes we've sent out so far that will or would have already crossed that line. If we assume we just happened to have sent out a sufficient number of probes, it would indicate that something is up but not what. The probable cause by physicists would be a radiation belt we weren't aware of in the magnetosphere of the sun. Any proposal that such a device would exist would be instantly shot down as there was no certifiable evidence. It would take a long time before any sort of mission would ever be sent with the chance of detecting such a device since probes would just keep failing. Manned missions would likely be not allowed by current space launch culture and the unmanned missions would have to get lucky and see an object vanish or try to reflect a beam off an object on the other side. And keep in mind that across millions of years there would likely be a range of orbitals with no objects. This again would probably be chalked up to be some gravitational event in the solar system formation we don't know about. Ultimately all of these observations would result as a "dead zone" on our map of the solar system but we wouldn't uncover the true cause. In summary, the device would likely result in a weird spot in astronomical data simply by virtue of losing probes at the same spot. However, the device itself likely would not be detected based on our current technology and the way space research is performed. [Answer] This is going to be a combination extended comment/answer. The final answer, really, seems to be reduced to 'what your plot demands'. Since the entire construct is hand waved, then you are free to choose. There are an abundance of answers that demonstrate the ability for it to be detected, but every one of these can be hand waved away so as to make it undetected. The ultimate answer depends on exactly why the aliens encircled our system in the first place. To contain us, or for some other purpose? If they intended to contain us, methinks they would have allowed for some mechanism for information to escape, so they could monitor us. How would they know what we are doing, if no information could escape? If it was for some other reason, what is the purpose of making the sphere undetectable from within? As a starting point for conjecture, suppose the aliens encased star systems randomly, in order to obtain every bit of radiated energy that cane from them? A mega-huge power plant? That is, a 100% efficient energy capture system. Any energy that was reflected back into the solar system would reduce the efficiency (although it would conceivably be captured at some point). But why would it also not increase the efficiency by capturing all energy coming from BOTH sides? Again, it can be posited that all energy entering the system would eventually be captured upon its eventual exit, so allowing it in is simply using the system as storage. I am thinking, perhaps, that it might need control signals to reach and exit the sphere? Sensors to detect how much energy was still left in the system? The Law of Unintended and Unknown Consequences can certainly have variable results in this scenario, in whatever direction and to whatever effect you want. But to absolutely constrain these spurious effects, I would suggest not one, but two spheres, one inside the other. Anything entering the outer sphere from the outside (even if transversed the outer sphere several times) would be allowed to exit the inner sphere into the solar system, but if it went from the inside of the system through the inner sphere first, again even if it oscillated across the inner sphere boundary, it would be 'captured' and not allowed to escape the outer sphere. Thus, any products of decomposition from anything entering through the inner sphere would not be allowed back out, either through the inner or outer sphere. (This hand wavium rule allows for modification so some limited reflection back into the solar system can happen if desired). The particles would not have first come in through the outer sphere, to gain them immunity from capture. That is, the inner sphere is completely transparent to anything coming in in one direction from the inside, and is completely transparent from the other direction to anything that came in through the outer sphere. It is opaque in this direction to anything that originated inside the sphere and did NOT come in from the outer sphere. The outer sphere is completely transparent to anything that came in from outside of the system, but in the other direction is 100% opaque to anything that came in through the inner sphere. What happens between the spheres is far game for whatever hand wavium rules you wish to apply, what happens outside of the spheres is subject to all laws of physics. This allows for the modification of the hand wavium zone to allow for whatever results you need. If the aliens need specific information to pass, there can be specific rules inside the hand wavium zone that allow for it. If the plot requires the sphere to be detected in some way, the rules in the hand wavium zone can allow for some reflection. If the plot calls for the spheres to be completely undetected, then the rules of the zone can say such things as 'if it came in originally through the outer sphere, it is remembered and can be tagged as external, so it will be allowed back out at any subsequent time (even though it is allowed into the system through the inner sphere, it will time-limited be considered 'external') or 'if it entered at anything less than a specific velocity or angle (meaning it was probably local to the Ort cloud) it would be immune from capture'. Though it is up to the author to explain or not explain why these hand wavium rules are applied by the spheres, given the nature of why they were created in the first place. [Answer] Objects with rotation will pass through the barrier with a section sheared off, or they will have flat surfaces because of sections that attempted to leave while the barrier was intersecting the object. If the object is big enough, slow moving enough and has a fast enough rotation then this feature may be noticeable. You also need to think about what happens to angular momentum in this case. Since you've responded to other answers with "yeah but magic!" I can't tell you how this would work but in the real world there would be an issue with the moment of inertia suddenly changing and the object's trajectory suddenly changing without any force being applied to it. Which is another problem you're going to have to "magic away". ]
[Question] [ On our world we have any number of creatures that use: * [Noxious Chemicals](http://en.wikipedia.org/wiki/Bombardier_beetle) * Poison(Spiders and Snakes being the obvious examples) * [Sound](http://www.telegraph.co.uk/news/worldnews/northamerica/usa/1320601/Dolphins-use-sonic-booms-to-kill-prey.html) * [Electricity](http://en.wikipedia.org/wiki/Electric_eel) as an alternative to their teeth and claws. One thing that we don't really have though is creatures using light as a weapon, I don't mean using it as lures, bait, or for attracting a mate. I mean actual light used to damage the target. It would probably make sense if it was aimed at the targets vision but something more dangerous would be even better. So the question is, how could a creature (plants are acceptable) evolve to use light as a weapon. How would that weapon work and what would it look like? [Answer] **Lens Trees** Unlike standard Earth trees, Lens trees approach gathering light from a different perspective. Earth trees grow as many leafs and branches as possible, spreading out to gather light and turn it into food. Early Lens trees instead grew leaves of crystalline minerals, shaped into oval lenses, that gathered and concentrated light into lower areas of the tree where photosynthesis would occur. Structures would "move" by either hydrating or removing water, causing them to bend. This allowed the tree to focus and concentrate light throughout the entire day. Over time, Lens trees evolved and adapted this light concentration method for other purposes. The first alternative use was likely to reduce competition - these Lens trees would use their concentrated light to burn out nearby competing plants, allowing themselves greater access to resources. This version of the plant quickly took over most of the planet that receives direct sunlight for most of the year. Modern Lens Trees have taken this to incredible levels of sophistication. Many varieties of the trees have developed various mirrored surfaces, which they then use to direct concentrated light back up through other lenses that concentrate it further. This is used defensively, to blind or burn bird-type animals or insects that would otherwise attack the tree. The trees have also developed incredibly complex organs that appear similar in structure (if not in composition) to animal nervous tissue. These appear to allow the trees to use their control and detection of light as a form of radar, letting them pinpoint targets both in the air and on the ground and then attack with concentrated light. Finally, Lens trees will occasionally "bathe" themselves in this concentrated light to kill any parasites or unwanted guests. **Night and Clouds** Lens trees are more vulnerable without normal sources of light, and it's likely that they would have died out early in their history if not for a symbiotic relationship with another, bio-luminescent plant. This plant has grown so close that it appears to be part of the Lens tree - it was only through DNA testing that it was revealed to be a separate species. While this plant cannot sustain light, it can create bursts on request from the Lens tree, allowing it to defend itself for short periods even when the sun is not available. [Answer] The problem with how a creature could evolve to use light as a weapon is inherent to the issue presented - **light does not make a very good weapon**. Even with all the technology that we currently have, light has several very important disadvantages: * poor efficiency of generating mechanisms when approaching damage-dealing energy levels * very poor energy transfer * is easily deflected or absorbed by even the most rudimentary armor (shiny or dark and matte, temperature-resistant material) * needs to be focused and directed or it dissipates * susceptible to environmental disturbance (dust, fog etc. blocks it) * telegraphs attacker's position when used Thus in a fight light is usually used as a **distraction, lure, stunning mechanism or for communication.** However, if we put all of these aside, how would that happen? **Light may be used to blind the enemy**, which is an attack in its own right. It could be used as a defense mechanism, assuming the predator usually looks at his target, a sudden flash of light might blind or stun him. However, biological mechanism used to generate sufficient amount of light might be tricky to design. You could consider **plants that have an amount of [flash powder](https://en.wikipedia.org/wiki/Flash_powder)** in a pod-like or hard shelled compartments used to discourage foraging animals. A predator could be **using external light sources**, e.g. biological lenses to focus sun's rays on it's prey. While this would be a cool way to cook its meal in the process, it is rather complicated and unnecessary. For a **laser-like damaging light, forget it**. Biological sources don't generate nearly enough energy to be converted to a laser-like beam. Also, [coherent light](https://en.wikipedia.org/wiki/Laser#Stimulated_emission) emitted by lasers requires much better quality of optics than anything known to biology. The question behind a question is in fact the issue with inefficiency and difficulty employing this mode of attack. **Unless you would design your world using very strange, pro-light anti-claw characteristics, a good old rip & tear will trump shine & burn anytime.** And since you ask about such weaponry as an effect of evolution, which assumes light would be somehow preferable as a weapon to other ones, it simply **wouldn't happen.** [Answer] # The Reflecting-Oven-Jay This is a small African predatory bird with a perfectly smooth set of wings with an area of ~100 cm2, so maybe the size of a pigeon. It hunts in large flocks, around 10,000 birds to a group (there are plenty of real birds that form flocks this size). Using some basic multiplication, this flock can focus about 130 kW of sunlight. The flock decides to kill and eat an elephant, who has a metabolism of around 3000 Watts and already has to work to keep cool on a warm day (heat sink ears, spraying water on itself, etc). By spreading out and focusing sunlight on the elephant, the birds totally overwhelm the elephant's ability to cool itself, raising its body temperature by about a degree Celsius every 2 minutes (130 kW / 4 tons\*specific heat of water), leading to slow heatstroke and death. Divided evenly, there's a lb of meat for every bird in the flock, a huge windfall, sustaining the group though any cloudy days until the next kill. [Answer] This first part is sort of a wind up, skip to **The Good Part** for the good part. As other posters have said before light isn't a very good weapon. But they haven't explained why that is. The reason it's not a very good weapon is because it's too diffuse. Think of it this way, if you put a hose power (~750 watts) of power through a light bulb even if you opponent is say ~10 cm away from the bulb the energy flux hitting their body, even at its closest point is about a watt/cm^2 which would be pretty uncomfortable (it's about 4 times the intensity of sunlight), they would only end up absorbing only about 1/2 a horsepower over their entire body which is about 1/4 the intensity of sunlight. Contrast this with spending one horsepower over one second to accelerate a human arm (~10kg) to ~28 miles per hour. Professional boxers punch at ~25 miles per hour and though they likely have the rest of their bodyweight behind that, they're not throwing one of those every second like we are here. Clearly kinetic attacks make more sense. Even if you could direct all that light into a 45 degree cone which would increase the power by about 8 times you're still not accomplishing much, especially when you realize, in order for your animal to generate that light, they have to be much closer to the light source than their opponent will be. The only way to really turn light into a weapon with substantial advantages over kinetic bombardment is with coherent (laser) light. Coherent light stays pretty well collimated over reasonable terrestrial distances so long as it doesn't turn the air into plasma. Until [very recently](http://www.bbc.co.uk/news/science-environment-13725719) there have been no biological lasers. There's probably some sort of evolutionary biology reason why this is, mostly because it's useless unless you can generate a whole lot of light (which nothing has evolved to do anyway) and have a big enough brain to aim it at a target. This doesn't address dazzler (bright lights which are supposed to make things blind) type weapons, in fact, now that I mention it, I'm surprised there haven't been any animals to use this. That probably has to do with the theoretical maximum efficiency of bioluminescence or something... I don't know. **The Good Part**: Anyway, none of this really answers your question, it's more of an argument for why light weapons never evolved in the first place, but let's forget the evolution part. Lets think about the traits of an animal which would use laser weapons. It would probably live somewhere with a lot open space, and good line of sight, improving this it could be a flying animal. Typically most high powered lasers we have today are chemical lasers so the animal might be a big gas bag or something. I would imagine only carnivores would have a high enough calorie intake to generate laser pulses. Hmmm... a big flying carnivorous gas bag. Where have I seen that before... Ahh yes. Allow me to present the **Gas Dynamic Laser Dragon**. A [Gas Dynamic Laser](http://en.wikipedia.org/wiki/Gas_dynamic_laser) (or GDL for short) is a laser which is powered (or pumped as they say in the business) by the rapid expansion of gas rather than electric discharge like most other gas burning lasers. A GDL can be pumped by the combustion of of some gas who's products are the lasing medium which is then excited to produce light which is bounced around inside a tuned cavity. The cavity is just a space with a 100% reflective mirror on one side and a less than 100% reflective window on the other. The beam comes out the window. Our Gas Dynamic Laser Dragon (GDLD) would, like most dragons be capable of combusting gases within itself, but this gas would be channeled downward through supersonic expansion nozzles made of bone (or preferably titanium) into a cavity which the dragon would have some muscular control over the shape of. On one end it would have a mirror and the other a window. The materials these are made of depend on the frequency of light laser produces which depends on the gas used. After the gas moves through the cavity it would leave the dragon as exhaust. If we put this nozzle/cavity/exaust system into the dragons head/neck it would be easy to aim and the beam could leave from the dragons mouth. Its esophagus could be used as the cavity if the mirrors slide into place when they're needed. I don't know enough about GDLs to choose a good gas, but the explosively pumped GDL laser gases listed on the wikipedia page list two bio chemicals which, though at least one of them is toxic to humans, likely could be created in the dragons gut by some enzyme. Okay, okay, lets be reasonable here, an animal like this probably wouldn't be able to fly, but still, a giant laser breathing lizard is about the coolest thing which could fight with light. For perhaps a more reasonable, though still pushing it, example there are the sunflowers from Larry Niven's Known Space. The flowers or leaves of the sunflowers were reflective and grew into a parabolic dishes which could reflect sunlight into a bulb of chlorophyll. The plants also had a way of detecting non sunflower life and could, when cooperating with many other sunflowers, focus their light on the offending plant or animal to kill it, providing nutrients for the sunflowers. [Answer] The obvious answer to this question would be to blind or to stun - not unlike the current worlds flashbang. But let's take a different approach. Lets look at ants for example. What if the light could be focused into a point, and, if your creature were big enough, basically act as a giant magnifying glass and cook it's victims to death. Roasted prey.... tasty. So how would it come to be? Imagine a world where the entire surface of the planet was unstable and completely random. Balance on the surface would possibly require more than one tail, to start off with. Perhaps, 9 for example since it's a nice number. Maybe it's a really sunny world, and there are lots of creatures that are adverse to light that hide in pockets of shade in the nooks and crannies. It all started out with your creature trying to get those little buggers out of the holes. Eventually, one of them mutated a lens in its tail. This lens could be used to redirect the sunlight into the shadows so it could get a better look at it's prey or whether it's there or not. Eventually, it grew more lenses in order to see more places or get more light into the shadows. Finally, it discovers that it could use all the lenses together (many magnifying glasses) on a single point in order to burn it's prey, or cook it alive if it were trapped. Voila! Light as a weapon! [Answer] Directly, I don't think there is much that light can do other than to blind a creature. Whilst I suppose that constitutes damage, I don't think it would be enough to directly hurt either a predator or prey. Blinding another creature would then leave it very vulnerable to attacking with teeth/claws in order to finish it off. But it would require a lot of energy to produce such a significant amount of light, so I'm not sure whether it would be useful or not, in terms of the creature surviving or eating the blinded creature to restore the energy used for the light show. It could always be indirectly damaged however. As indicated in the question [here](https://worldbuilding.stackexchange.com/questions/14861/could-an-animal-species-evolve-to-use-electricity) the light sources could be used in a way that would frighten predators/prey, putting them into a state of submission. Extending tentacles or antennae with lights on the end and flaring them up in the darkness would make the creature appear to be bigger than it actually is, achieving this effect. Once the animal that has been attacked is in a frightened state, it would likely be much easier to escape or attack them as they are disoriented. An animal creating light could always make it flash very quickly in order to induce seizures or hypnosis in other animals, making them even more vulnerable to attack (like how a [stoat dances to hypnotize a rabbit](http://video.nationalgeographic.com/video/worlds-deadliest-ngs/deadliest-stoat) before it attacks) but it would need a very specific predator or prey to succumb to it. [Answer] **Blindness** A sudden, bright flash of light can cause temporary blindness. Some sources claim that only if there are Ultraviolet or Infrared rays could you possibly get permanently blinded, while others claim that a long enough duration of a bright enough light causes heating of the retina if the energy cannot be dispersed quickly enough, and therefore permanent damage. However, perhaps on another planet where there is so little light that even a moderate light on Earth is "blinding"; light might be much more damaging to the other creature's eyes since they are not used to having to disperse so much light. --- **Long-term Aggression** Your creature could always be giving off a wavelength that causes radiation, which could damage the other creatures and plants in the vicinity, but I get the feeling you are looking for an immediate defense. --- **Immediate Physical Damage** Theoretically, something such as a laser or a series of incredibly strong pulses could "fry" the enemy, but the energy required to do so would be immense, probably much more than any single creature could generate. It is much easier for the heat from a reaction to harm something than to focus so much light that the heat generated from the light harms them. It would make more sense if you could redirect an already extremely strong source of light, yet the magnifying glass vs. ant effect only works on a sunny day and ants are very small. It doesn't take a ton of energy to heat their low amount of mass, yet consider how big the lens is compared to them. On Earth, a creature that redirects light would be ineffective whenever there's a cloud, not to mention the animals that might eat it at night. There's also the problem of having to create whatever biological material would allow a creature to have a "lens" in order to redirect and focus the light - it would likely be expensive resource-wise for the creature. That being said, maybe this creature lives on a planet which receives a ton of light due to many or close-by suns. Maybe any day-living creature has to develop a certain degree of reflective-ness(*not a real word*) just to survive the daylight. A large plant or creature provides shade and reflexively can withdraw that shade in certain areas to kill a threat or when it decides it is hungry. Maybe there is another certain creature which it provides shade too that is able to protect it at night, if such a world has a night. [Answer] Instead of the organism *generating* light as a weapon, you might consider an environment filled with dangerously high levels of radiation (e.g. a planet close to its sun). In such an environment, plant life could evolve to live off of this radiation and absorb it, creating shade below in which more sensitive organisms could survive. These plants could defend themselves from the peskier of these shadow dwellers by developing mechanisms to selectively allow radiation through the canopy whenever the plant's roots/stem/etc. are touched or damaged, irradiating the stimulating creature below. [Answer] There is a great example in an old "Blue Planet" BBC episode, "Into the Deep" (<http://www.dnatube.com/video/4767/Animals-in-The-Deep-Ocean-and--Bioluminescence-Part-2>) [starts at 5:15]. Here, a shrimp with bioluminescent ink sprays it onto the face of an attacker. Not only does it confuse the attacker and allow the shrimp to escape, but it sticks to the attacker's face, lighting it up and making it a target its own predators. While the light doesn't do direct painful damage, it does create a sort of blinding, and certainly does direct damage to the safety of the attacked fish. Pretty sweet. [Answer] Sharks with laser beams attached to their heads! Really your options other than blinding light, would be either a laser beam of some kind and that takes a lot of juice to produce one with enough power to harm, or we have to move one to fire. A short burst of light can be created with fairly small energy input, look at LED technology, if the animal can have some capacitors to store the energy to a quick release they could use it to blind and confuse a predator, kind of how zebra stripes work but much more distracting. Predators with this ability would be pack hunters and would use it to scare and herd their prey, likely to an ambush. [Answer] Killing a creature with light would be too hard, so how about blinding prey? Such a creature would blind then pounce. It would be fast, and it would be small, because it takes less light to disorient. It would gain the energy to make light by eating. Because of its style of attack and its method, it would rest for most of the day or more. The light would be created through short, intense flashes of bioluminescence. [Answer] Light as a killing weapon is not going to work. Justification for my blanket statement: Do you know of any human hunter who uses a laser instead of a gun? Light as a stunning weapon is already known to work. To wit (always wanted to say that): it is illegal to hunt deer at night in conjunction with a spotlight, because it's not sporting, since it freezes the deer and allows the hunter to pick them off at leisure with his rifle. Even better (and more do-able, biologically) would be a flash-blinding weapon, used by night hunters. This would be especially effective if the terrain were inherently dangerous (e.g., cliffs, jagged rocks, plants with poisoned thorns). In that case the hunter only has to flash-blind the prey and scare it into running away blind. The prey is likely to kill itself, so the hunter didn't have to be fast/strong enough to kill the prey. Seems like this has a chance of evolving, from a bioluminescent mating lure, to a prey lure, to a (sexually dimorphic) display of virility, to a flash-confuser, to the flash-blinder. The hunter could actually get less deadly as the light power increased, and its favored habitat might change. [Answer] You Can think about the a large panel of mirrors or lenses with variable **reflecting/refracting index** that can focus a large amount of Light at one place on variable distances. This can cause a huge damage on any creature when exposed to that focused energy. --- Here is the **Idea**. Imagine a creature who are having some part in there body filled with some transparent liquid and they can vary the concentration of that liquid and can also give a different shapes( More similar to lanses i.e. concave or convex). **Now Working Principle of Lense is as** "A lens produces its focusing effect because light travels more slowly in the lens than in the surrounding air, so that refraction, an abrupt bending, of a light beam occurs both where the beam enters the lens and where it emerges from the lens into the air." It also depends upon the material used for making the lense. For example refractive index of the water is ***1.33*** and for glass it is ***1.62***.**More will be the refractive index of the material it will more bend the light. In other words you can say it is the bending capability of light.** In optics the refractive index or index of refraction n of an optical medium is a dimensionless number that describes how light, or any other radiation, propagates through that medium. The point of discussion of refractive index is directly related to the concentraion of liquid that the creature will have. As creature is able to do modification in shape and Concentration of the liquid that creature will be able to bend light according to the choice and by this he can also focus it at whatever distance he want. He can focus the light on some other animal or something for doing harm or for killing it. [Answer] IIRC sunlight actually has been used as a weapon at least once. The antic warriors focused their copper shields on the mast of a galley and caused a fire. In your imaginary world, you can give this light-reflecting weapon to either social insects or to some big animal that predates social insects. The latter would have to possess some king of a large mirror, that would be focused onto the insect nest. This is not really meaningless even on Earth: the bees escaping from a fire cannot bite because they load themselves with honey, as much as they can take. Hunting moving animals with reflected sunlight would be a bit more tricky, but still possible. How evolution could lead to this? A reptile with big ears (or wings) could use the reflected heat to soften or melt bee wax. After developing the mirrors, the animal could use them on different targets, e.g. blinding and later burning a mouse before eating it. Such evolution is possible, say, if the wax melting creature lives on a peninsula, then the peninsula becomes an island, big predators disappear, the creature becomes a predator itself, and then the island once more becomes a peninsula and the creature goes to the continent. One more use of the reflected sunlight frying could be to neutralize the poison of some prey or plant, but such animal would be very much specialized on a single food source. [Answer] As stated it's very hard to imagine this being viable, but the best option to me would be confusion and misdirection. Imagine an area with unusual light patterns, possible in a dense forest where light filters through trees in unusual patterns, or in the ocean. A creature that could slightly light up various part of their body may be able to create odd light patterns that would confuse those looking at them. In effect they could make something like an active camouflage effect where constant shifting and flashing lights confuse a predator on the exact shape, distance, and movement of the creature it's chasing by making it hard to process the constantly changing light patterns. Realistically the expense of producing these lights is high enough that it's hard to think of it as adaptive, but it's less implausible then many of the other options. The key would be to make an enviroment with limited light in unusual light patterns, and when which is pretty congested so that fleeing a predator was less about raw speed and more about being able to duck around foliage and through areas the predator has trouble perusing etc. Then when being chased you turn on the light show to make the predator have a harder time following your movements so he can't detect that your shifting your weight to dive for a whole in the brush until after you have done it and his inertia took you past him. Keep in mind in this case I'm not talking about high light show, were talking about very small shifts in light pattern. Putting out light is expensive, the less light you need to use the better because it costs less. With this approach excessive light wouldn't help, it's intentionally making constant slight shifts in shade and lighting that works because it's subtle enough to make it feel like the changes could be due to odd light filtering down on the creature. The effect works through subtlety and randomness, not by overwhelming the opponent with expensive energy. Still...I don't really believe it could evolve. I'm doing my best to give a valid answer but my real answer would be that no creature would evolve using light as a primary weapon. [Answer] Others have put up some good ideas for how to generate light. As eimyr pointed out, tooth and claw is going to be a lot more effective than shining a bright light on them, though using it to blind/stun isn't a bad idea. Here's a possible why. If their primary predator was photo sensitive, then a light attack would do more damage than it would to you or I. This would be a bit like a vampire in the sunlight, or the underground monsters in Pitch Black. There is a [rare genetic condition in humans](http://en.wikipedia.org/wiki/Xeroderma_pigmentosum) that makes them more sensitive to light. If the predator had a severe case then being able to make light would be useful. [Answer] Well, consider "Tapetum lucidum" a alternative. <http://en.wikipedia.org/wiki/Tapetum_lucidum> Imagine a animal with very big eyes walking on the sun. It preys on big animals that does not get it like a menace because it is smaller. It get close and close to the point it is facing the big prey. So it manage to look to the face of the prey and... full open its eyes, making the prey blind by a flash of light. Just a moment and the predator cuts the prey's troath with it's talons. Maybe beasts like this one could had lived along dinosaurs. ]
[Question] [ Let us assume, for the moment, that we have an army of (Tolkienesque) elves to equip, and only modern small arms to equip them with. However, elves have hearing that is rather more sensitive than humans (by at least 10-20dB). This is great for avoiding ambushes and tracking prey in the deep woods, but has a distinct downside on a more modern battlefield, as unsuppressed firearms are ear-splittingly loud beasts even to human ears, and to an elf, such a loud noise at such close distance could very well be downright disorienting and/or lead to rapid(!) hearing loss, neither of which are good. Given this, how could our elven army make effective use of modern firearms technology? Would suppressors be standard issue for them? Could active hearing protection provide enough protection to keep elf ears from being shattered by gunshot noise, while still permitting them to communicate effectively? Assume that they have to fend off a human army of roughly equal numbers for the purpose of this question. [Answer] **Elves don't have the same health concerns as humans.** Elves are elves, so inherently have superior biology to humans. When your lifespan is thousands and thousands of years you're going to need eyesight, hearing, teeth, joints, and mental acuity, among other things that don't degrade so quickly with wear and tear or time. Or else you would not be a very pretty sight after 70 years, let alone 700 or 7000. and we all know that elves are still very pretty when thousands of years old. So it is not only expected, but necessary that elf hearing not only be much more robust than human hearing, but also capable of regenerating. As a matter of fact, most animals in the real world do regenerate their hearing. The fact that mammals do not is an exception, not the rule. [Answer] **Noise-cancelling plugs.** Essentially, you'll be wanting to cut out the very loud cracks and bangs whilst still being able to hear some kind of signalling and communication for coordination of movement and action. I'm discounting radio as it's too easy to interfere with. An ear-plug with a small speaker incorporated, a bit like ear-buds but more focussed on blocking outside noise would be needed. These would be connected to an electronic device with mike, with a digital filter which has several modes at the touch of a button: * Battle Mode: In effect to take-out the loudest and most damaging sounds - by means of signal compression. This will mean the highest dB sounds are still there, but at a tolerable volume and make some of the quieter sounds a bit louder. This would suit the heat of battle with live-fire close at hand. * Stealth mode: like it says on the box, this reproduces the soundscape faithfully and as much like normal hearing as possible without compression. Both modes can have the additional feature of enhanced ultra-sonics. Now, I'm assuming that elves have pretty good high-frequency hearing compared to humans anyhow - and the humans will expect them to be using dog-whistles to communicate. Even higher frequencies can be [converted to the audible range](http://bertrik.sikken.nl/bat/convert.htm) (frequency divider), enabling the normal high-frequency range of elves to be used for decoy and misinformation whistles, and the even higher range for actual signalling - tactical use of comms.. [Answer] ### Range and resolution are separate things How accurately you can measure, and how far you can measure, are not the same. Make everything a lot bigger, say with an eardrum the size of a stadium, and now think about measuring it. Human hearing would equate to measuring the drum movement with a ruler marked only in whole centimetres. Elf hearing instead would be like measuring the drum movement with a ruler marked in millimetres. Elves can simply resolve that eardrum movement better. How far can you measure though? In other words, how loud can things be? There's no reason the rulers can't be the same length, so the maximum amplitudes for elf and human hearing would remain the same. This would have an evolutionary basis, of course. Elves and humans are living in the same world, with the same "normal" amplitude of loud sounds like falling trees, strong winds, lightning, and so on. If ancestral elves were paralysed every time there was a storm, they would have been been eaten by wolves pretty quickly! Owls and other birds that hunt by hearing don't have any problems with loud noises like passing cars or gunshots, beyond seeing them as human-related threats, of course. In other words, evolution will already have ensured elf ears are just as tolerant to the noise of gunshots as human ears are. I'd note there that human ears aren't very tolerant to that noise anyway, and [hearing loss is incredibly common for soldiers in active service.](https://mmrjournal.biomedcentral.com/articles/10.1186/s40779-015-0034-5) [Answer] Wouldn't ancient and medieval battlefields also be quite noisy, with men and animals yelling with excitement and fear and screaming in pain?. I wonder how the noise in medieval battles or in modern reenactments of them compares to the noise of battles in the gunpowder era. Suggestion One: Use noise reduction equipment. Once I was getting rather deaf so I went to the doctor. The doctor said I had a build up of ear wax in my ears. So he got a syringe and started squirting water into my ears to dislodge the ear wax. I could feel the water squirting in and after a while I suddenly heard a loud noise like a toilet flushing - the water sloshing around in my ears. And I also heard loud noises I hadn't heard earlier in the office. It sounded like the docotor's office was being demolished around me. My brother-in-law and his crew were doing some construction and remodelling work on the office building. And for the next few days, until my ears and brain adjusted to the unexpected clear path to my inner ear, everything sounded louder. So it is possible to completely block the air passages in the outer ear and reduce the sound level heard by many decibels, so that loud noises sound faint. So ear plugs and other noise reduction gear should be adequate in protecting elvish ears. And possibly the Elves might wear environmental suits in battle with helmets that give them their own air supply. They could have microphones on the ouside of the helmets with speakers inside the helmets, and the circuitry could be designed to automatically adjust the volume inside to keep it at comfortable levels. Considering how fast modern electronics work, that should cause a sound delay of only a few thousandths of a second, too short to notice. Maybe the Elves don't have access to early 21st century technology like we do. What could they replace electronics with in that case? I don't know, maybe magic? Suggestion Two: Make guns quieter. What about airguns? The first airguns using compressed air were invented centuries ago. I think that about 1780 an entire regiment of the Austrian army was equipped with air rifles. If someone invented portable steam engines to power the pumps that filled the compressed air containers with compressed air, an entire army could be equiped with compressed air rifles. The USS *Vesuvius* of 1888 was a dynamite gun cruiser. <https://en.wikipedia.org/wiki/USS_Vesuvius_(1888)> > > A dynamite gun is any of a class of artillery pieces that use compressed air to propel an explosive projectile (such as one containing dynamite). Dynamite guns were in use for a brief period from the 1880s to the beginning of the twentieth century. > > > <https://en.wikipedia.org/wiki/Dynamite_gun> During the late 19th century dynamite was one of the best explosives to use in artillery shells. Except it tended to explode in the gun. > > Because of the instability of early high explosives, it was impractical to fire an explosive-filled shell from a conventional gun. The violent deflagration of the propellant charge and the sudden acceleration of the shell would set off the explosive in the barrel of the weapon. By using compressed air, the dynamite gun was able to accelerate the projectile more gradually through the length of the barrel > > > Guns for naval use were supplied with air from shipboard compressors. A small model for field use by land forces employed a powder charge to drive a piston down a cylinder, compressing air that was then fed into the gun barrel. This field model was famously used by Theodore Roosevelt's Rough Riders during the Spanish–American War, but had actually been used previously by Cuban insurgents against Spanish forces. > > > <https://en.wikipedia.org/wiki/Dynamite_gun> So long as the enemies of the Elves don't invent conventioanal rifles and artillery that is significantly superior to the compressed air rifles and artillery of the Elves, Elven weapons should be adequate on the battlefield. I note that the superior hearing of the Elves would enable them to locate the quiet sounds of enemy compressed air artillery firing much better than humans could. [Answer] Human eye and photo camera adapts to excess of light by having contracting diaphragm. A super-sensitive ear is also likely to have some anatomic features to limit sensitivity in very loud environment. The internal hearing channel can be closable. [Answer] Only use noise-canceling headphones. If less technology is available just use standard range hearing protection, you'd be surprised how much you can muffle the noise with just the basic earplugs and headphones are even better (I have experience shooting firearms). ]
[Question] [ Imagine a Yorkshire hill. This place is like that Yorkshire hill in all aspects except for those I describe. Its size is 100km by 100km, with a slope of 0.5%. When going up the slope and crossing the edge one would pop up seamlessly on the other side but 200m lower down with regards to the way gravity is pointing. The opposite would happen when crossing the border when going down (being popped to the top of the hill 200m higher in elevation and 100km over). The sides do the same to each other but without the change in elevation. If visibility was good and nothing was blocking your view then you would see yourself infinitely many times all 100km apart. There will be some forest, some meadows, plenty of water, air, and light. Just an idyllic place to live. Were it not for being trapped within. It would be like the Truman Show but contained by something like invisible portals. Working in a similar way as those in the portal games. ## A diagram for clarity You can see meadows(light green), forest(dark green) and rivers(blue) [![enter image description here](https://i.stack.imgur.com/ZmHpj.jpg)](https://i.stack.imgur.com/ZmHpj.jpg) The two red borders are the sides and just plop you (anything) out of the other the same distance away from the dark blue border. The dark blue and purple borders do the same with respect to the right red border. Only there is the added change in elevation. I have made sure that the blue river and streams are continuously flowing downhill. What would the weather be like? Would there be a constant wind? In which direction? Could it be quite regular due to its small size? Would you often see clouds? What kinds? [Answer] With is what I can say from my physics studies : ## The need for a homogeneous pressure The pressure is continuous in space, otherwise a sudden air movement occurs to get back to continuity (we usually call it an explosion). However, in a real atmosphere (take Earth's as a representative exemple), the pressure [changes with altitude](https://en.wikipedia.org/wiki/Vertical_pressure_variation). Here, this would imply that their is a pressure discontinuity between the sides of different altitude. As we've seen, this cannot be stable, so the pressure must not change with altitude. We end up having a toroidal **atmosphere with homogeneous pressure**. As a scenario, you can imagine the beginning of this world like EdwinW in his answer : a single normal cell with real atmosphere suddenly wrapped around itself in a torus. Then there is an initial pressure discontinuity, but the initial bang (one could actually call it the "big bang", lol) would neutralize this discontinuity. As there would be no pressure-related acceleration mechanism, the initial wind created by this bang would eventually stop as the atmosphere would evolve towards a homogeneous pressure, which is essentially the case I will develop further on. ## This homogeneous pressure makes wind The pressure being the same everywhere, the only non-neutral force is weight, pulling air down the bottom. However, usually the ground counters this effort vertically (that is, perpendicular to its surface), but here is *always* counters it by a sideways force because of the slope. This phenomenon would be the genesis of wind : at the beginning of times, this resultant effort pushes the lower layer of air downslope. As the lower "layer" flows down, it pulls with it "layers" from higher in the air, building a [boundary layer](https://en.wikipedia.org/wiki/Boundary_layer) which would grow up without end. As the winds gets faster and faster as a result of "falling" down an infinite slope, it is more and more slowed down by the ground itself (mostly by trees I would say), and **it will eventually reach a maximal velocity**. Note that it can be quite high, it's up to you to imagine how much if you don't want to run the computations. It's mostly here that you can trick with the physics of your universe to make the wind speed compatible with life. But since the slope in infinite, there is nothing that can stop the wind : you get a **homogeneous downslope wind**. From then on, at a given altitude (perpendicular to the surface) **the wind speed would be constant** or periodic, since it must be the same at each boundary. I guess obstacles could create a small periodic variability of windspeed, but not so much that it could turn around for instance. This effect of the ground slowing down air would become less visible in altitude, so **the higher (perpendicular to the surface), the faster the wind is**. If the wind reaches supersonic velocity, each obstacle on the ground would create a [shock](https://en.wikipedia.org/wiki/Shock_wave), and complexities would arise in the overall picture... ## Other weather features Having a very fast homogeneous downslope wind is already quite an interesting weather feature. However we can imagine other perturbations on top of this, as long as they are periodic with regard to the boundaries. For instance, there could be a **constant or periodic wind sideway** in either direction. I wonder if any rotating speed variation of the wind (like a hurricane) could exist with a diameter larger than 100 km... it's an interesting question. ## How loud sounds behave There are interesting phenomenons that happen when a sound crosses a whole cell (100 km x 100 km). I agree that a sound must be quite loud to cross 100 km but let's imagine. You can hear an **echo** of it from the other direction, but it decreases in strength at it usually does in air. If you have a constant loud sound (say you shout with a tremendous voice), **the sound will [interfere](https://en.wikipedia.org/wiki/Wave_interference) on the borders**. You would have both constructive and destructive interferences, and thus a whole interference pattern. It may be feasible to have a constant self-powering noise if the original source is loud enough. We must take the wind into account and it adds a [doppler effect](https://en.wikipedia.org/wiki/Doppler_effect). So if you sing really loud, you may here yourself on different frequencies (depending on the wind speed). Depending on the musical faithfulness of the frequencies, you may be able to **sing a polyphony despite being alone**. You definitely created a very interesting universe ! [Answer] **Perpetual Downhill Cyclone** Imagine a bowling ball placed at the top of the slope. It rolls downhill for 100km and then teleports back to the top. Now it is where it started but moving faster than it was before. It rolls downhill another 100km and then teleports a second time, moving faster still. This proceeds until finally it is moving fast enough that the air resistance on the next downwards trip cancels with the increase in speed. Now imagine a million billion tiny bowling balls (air patricles). They are pulled downhill under gravity and teleport to the other side and are pulled down again. This results in a perpetual wind blowing downhill around the world. It might be a gentle breeze or it might be a hurricane. I don't know the relevant equations to model this. This of course is a perpetual motion machine. Every teleport adds energy to the system. Air friction causes the world to heat up over time. **Note:** I am assuming gravity is straight downwards. The direction does not change from one point of the slope to another. [Answer] Edit: I expanded my answer in response to comments by @Daron. There would be a steady downhill wind, possibly quite a strong one. 0.5% of 100 km is is half a kilometre, 500 meters. Suppose upper side would not be connected to the lower side and we take the lower side is assumed to be at sea level. The pressure at 500 m elevation is about 60 millibar lower than at sea level, about 950 millibar. This would be a equilibrium state. If we now connect the two sides, air will start to flow from the high-pressure zone to the low-pressure zone until the pressure equalises everywhere. In the real world, pressures as low as 950 millibar are normally strong enough to produce moderate hurricanes. The mechanisms are not necessarily the same, but it's the only clue I find on how much wind you get when equalising the pressure. If I'm to guess I'd think you get stronger winds in your world than would be suggested by the hurricanes, but that's conjecture based on the fact your system would be permanent. What you want to find is the equilibrium state where the air is moving fast enough to stabilise the pressure. Without some mechanism significantly slowing the wind down, not just on the ground but at high altitudes as well, your world would experience a perpetual storm. Edit: I should give some references... According to the diagram at [this site](https://www.researchgate.net/figure/Pressure-vs-height-According-to-this-model-pressure-drops-by-about-011hPa-for-every-1m_fig1_269306407) the pressure at 500 m is about 955 millibar, and according to [this site](http://www.pcwp.com/sss.html) 955 millibar corresponds to a category 3 hurricane. [Answer] ### Fun things This is a fun question, although other answers have covered the main points already. I'll look a bit at how *not* to doom your world. --- #### Infinite tiled plane (doomed if left as-is) First, I'll look at it from a different perspective, slightly counterintuitive. The ground is flat, but gravity is crooked (and height-invariant). We're standing on an infinite plane that happens to start as a precisely-equal repeating pattern. (That's what it'll look like from inside, and it's equivalent.) Air will fall sideways, and so will water. This will cause erosion, and there's nothing but the inertia of the ground to stop the erosion. Your atmosphere will tumble down this slope, never pooling at the nonexistent bottom. Soon voracious winds tear the ground up. If gravity fades out with altitude, it's disturbingly easy to achieve escape velocity, and most of your atmosphere probably will. ##### Preservation Suppose that the portals cease to function below ground level. This means the ground has something to push against, and will be held up as if by terraces on the infinite plane. The wind still shreds everything, but the debris doesn't necessarily lift into orbit in a plasma cloud. Suppose that the ground rests on a frictionless solid plane. Then the whole world accelerates at the same pace, and settles into balance. **Survival**, but the world is constantly accelerating, so the wind and water will be moving pretty fast. However, you can fiddle with your slope to moderate that, or erect large sails or specialised trees. **This only controls for the slope**, the portals/tiling can still doom your world. Because you're accelerating, you'll get a Doppler effect for light as well as sound, although it's unlikely to be redshift-worthy outside specialist studies. --- #### Sunshine Another answer mentioned this could destroy your world, purely because of the tiling. The theory goes that the walls will also make the sky look tiled into 100km squares, and that the Sun will appear in every square at once, giving your world a few moments of "touch the Sun" heat at high noon and complete night the rest of the time. In theory, this is balanced because the Earth has the entire night to radiate that heat outward, and it might be a nice plot point to have your world's temperature spike to lethal levels once per day. But it'll need some exotic vegetation to survive in it. This is not unsolvable. To save some time with altitude-shenanigans, we'll assume that light shines "down" matching the direction of gravity exactly. We need an average light-level over thewhole sky to match what the Earth sees (more or less). That's about one part in 100000, and will look like **a little over-bright speck overhead**. Shadows are crisp and always downward. To make things more interesting, let's consider a diffuse light source. Now **the entire sky glows** faintly, constantly, and evenly; and you're living in the Twilight Forest. (The *Edge*? *Minecraft* mod? There are a few of them about.) Shadows are very blurry. (NB: Your portals are still injecting energy into the atmosphere. You might want to turn down the Sun a bit to counter that heating, though most of the energy is accelerating the ground along its infinite plane. ##### What if we liked day and night? To get day and night, we only have to shine down from some areas more and others less. For the fun of it, we'll say that day and night look like great stripes moving downhill (and across a bit), 100km wide. By some trickery with angles (we're running lighting for *The Truman Show* here), we can have morning and evening. The fun part is when the atmosphere distorts the "sun", and makes it seem to twinkle: it will blink out for one moment, then stretch along the day-line the next. It will also seem to wobble back and forth in the direction that day moves, but remain fairly consistent in brightness. At 100km/24h, that means that day and night move at a comfortable walking pace. (Also, the remains of past morning/evening light could in theory form a tiny rainbow-aurora near the horizon, doppler-shifts affecting the angle. But atmospheric diffusion would blur this into oblivion unless you went into space. "Orbit" isn't a thing in this world, but you can stay up with minimal push ... in one direction.) --- ##### Sound The idea of singing to yourself is fun, but your sound will disperse just as it would in any other medium. A large shock (explosion?) will die out much like a ripple in a tank of water. If you have a very loud sound, you might be able to exploit resonance to create a standing wave - but this is mostly a concern for the weather, since it will take 50 minutes for a sound to do a lap of your world (ignoring wind). That very low drone might build up based on landforms, but I can't say whether it would *effect* or even much *affect* erosion. It would probably result in fun cloud-patterns, though. --- ### Weather OK, so to give a proper answer to the original question rather than just playing with your world: The weather will still be extremely windy. The entire world is accelerating constantly, and air cycles through the portals more often than the ground. This means that the atmosphere is dragging the ground faster and faster, and the ground is slowing the atmosphere ... a bit. Since the amount of energy you need to impart to the ground is a function of mass, I suggest the thinnest ground you can get away with, and a lot of forest to act as sails. A wet climate (more water in the air) will help your vegetation not to lose too much moisture to transpiration. Also avoid rivers, they will become boiling torrents very easily. If you do have one, let it be a small stream and human-made. This argues for a more arid climate. For a good idea of what the weather might do, look at an oil-and-water-between-moving-plates demonstration. There should be quite a few online. --- Thanks for asking this, and for reading an largely tangential answer. I hope it's helped you to avoid accidentally sandblasting/baking/sending-to-orbit your world. To quote the Discworld: "You might not get what you asked for, but you'd get what you *wanted*." I'm inclined to think you wanted solutions rather than problems. [Answer] # infinite downhill wind Imagine having 2 portals. One above the other. Drop a stone in the bottom portal and it'll fall out the top one, only to fall into the bottom one again. The stone will accelerate to terminal velocity, where it can't accelerate anymore because of the air resistance equalising to the pull of gravity. Your situation is much the same. You have a gentle slope, but one end is slightly higher than the other. With physics what they are your air column should be slightly heavier on one side. This is because the air column us higher, has more air and slightly more air pressure. Air behaves much like water. It moves from high to low places. So this is the first situation I would imagine. Only this isn't a stable situation. Right next to the downhill higher pressure and heavier air is a lower area with a lower air pressure. It'll move there to equalise the air pressure as well as to continue moving down the slope due to gravity. It'll appear at the top of the hill, meaning it can go further down or at least put pressure on the lower laying air pressures. That means the lower air column will be pressurised, making it a higher pressure than the higher air column. The cycle repeats, much like the stone falling in the first example. There are some extra factors here at play, like that the high pressure air column will heat up faster and generally be hotter than the low pressure air column. This will in general increase this effect. Will this lead to high winds? Incredible devastation of hurricane proportions that scrape the land clean of anything, playing with the dust in an infinite loop of speeding up wind? Probably not. Just like the stone there is a terminal velocity. Each air particle does bump into others when moving from one side to the other. Though other people can still conclude that in effect the whole column will start moving quicker and quicker, as the last air particle has moved a bit faster so there is less air resistance overall, I think it'll not be such a case. The column is small for air sizes. It'll probably interfere with itself too much. In addition, the gravity isn't very powerful and the air pressure differences are tiny on such a small area. It'll probably sort of equalise at a small breeze. I mean if you had an infinite water stream you would also not conclude it would be a torrent of high speed water after some time. It reaches a 'terminal velocity' rather sooner than later. ## Vegetation For growing vegetation and life it'll be more simple than you might think. Though large complex life will be relatively little due to limited resources, they can survive. The rest is very possible to live. It is much like those jars you can put some plants in and close off to the world. As long as there is sunlight it'll become a tiny ecosystem. Water evaporates from the plants but can't escape, which condensates and comes back to the plants. All nutrients are absorbed by the life and released again upon death. Your world is much the same only without walls. The water and nutrients stay within the 100×100km area. Only the sun is needed for the cycle to continue (near) indefinitely. That means if you start it during a time where there's a lot of water in the air and ground, you'll have more frequent rainfall. If you start it with less there is less to evaporate and reuse. It'll be a dryer climate. As the internal area does not change in the composition at all, the only factor of influence is the sun with the seasons. Assuming the sun is regular the climate can hardly change, save for incredible ecological destabilising things that release a lot of carbon for example. [Answer] It would quickly turn into a hellscape. As some comments and answers already explained, each teleportation would add energy to the system. As already said, if you had a bowling bowl falling in the air, it would accelerate up to a point where the acceleration cancels out with air friction, reaching terminal velocity. But this is much worse here, since it is the air itself that is moving, it has no "air friction" working against it, so the only thing that slows it down is not air friction, but friction against anything that isn't moving in the same direction. As things like dust start to move with the wind, they contribute less to friction, and help erode everything else faster, which reduces the amount of stuff that slows the air down. Unless there is no "ceiling" to the world, then I guess the atmosphere would spread out and "climb" as it accelerates, spreading thinner and thinner. If a particle has enough horizontal speed it could "do a lap" around the world fast enough to counter its own vertical fall, then, the upper layers of the atmosphere would be in low enough gravity, and encounter no resistance against the void, so that it could keep climbing this way indefinitely, leaving room for other particles below to go through the same process. But if there is a ceiling high enough that there is no "chokepoint effect" with stuff on the ground (which would still produce heat, it would go the same way but it would happen much slower as the wind isn't as free to accelerate), then the only thing slowing down the wind would be stuff on the ground, dust in the air would only slow it down a bit by hitting against grounded stuff, but the ceiling would probably be high enough (probably doesn't need to be very high for that) that the upper parts of the atmosphere can keep accelerating, only getting "second-hand drag" from the air below. But as things keep eroding, more particles enable more erosion, until a point is reached where enough stuff has eroded that the whole world can cascade into an infinitely accelerating cyclone, definitely turning into, as a comment said, some plasma soup. [Answer] Easy-peasy, just plant lotsa windmills and extract the extra energy. Let's see if it's feasible (spoiler: it is. Yes, it will spoil the vista, but it makes the place livable and... it's renewable :grin:) So, lets see how much energy the teleportation injects into the system at each cycle. The most defavourable case is when the entire landscape is isolated from the external environment, so that the air can't expand outside and carry an amount of energy in the process. Something like in the diagram below, representing a cross-section of the skewed prism (with the note that, at 0.5% slope, the $sin(\alpha)$ and $tan(\alpha)$ start to differ at $10^{-7}-10^{-8}$, so don't bother). [![enter image description here](https://i.stack.imgur.com/BG99I.png)](https://i.stack.imgur.com/BG99I.png) So, over the duration of an entire cycle of atmospheric recycle, the prism on top descends and replaces the equal volume of the bottom prism. With the note that the mass center of the triangle is 1/3 from its height (and thus $\Delta h = 2/3\cdot{h}$), lets compute the variation in the potential energy. $\Delta E\_p$ A triangular prism with a height of 100km (either top or bottom) will have a volume of $0.005\cdot10^5\cdot10^5\cdot10^5 = 5\cdot10^{12}m^3$ and a mass of $m = 5\cdot10^{12}\cdot1.22 kg = 6.1\cdot 10^{12} kg$. The potential energy difference is $$\Delta E\_p = m\cdot g\cdot\frac{2}{3}h = 6.1\cdot10^{12}\cdot9.8\cdot\frac{2}{3}\cdot(0.005\cdot10^{5})J = 2\cdot10^{16}J$$ --- Assume we want the wind to be limited to a $v\_{wind} = 10\frac{m}{s} (= 36\frac{km}{h})$. How much power we would need to dissipate in windmills? The entire prism moving downhill at $10\frac{m}{s}$ will have a kinetic energy of $2\frac{6.1\cdot 10^{12}\cdot{10}^2}{2} J = 6.1\cdot10^{14}J$, which is negligible with $\Delta E\_p$, so we'll ignore it in the balance of power. However, $10\frac{m}{s}$ comes into play in the time required for the entire prism of air to be recycled through the upper outlet port $T\_{cycle} = \frac{100\cdot10^3m}{10\frac{m}{s}} = 10,000s$. Which means the entire power that need to be captured by windmills is $P = \frac{\Delta E\_p}{T} = 2^{11}W$. One of the current most common [size and power of the wind turbines](https://blog.arcadia.com/common-sizes-wind-turbines/) is > > the GE 1.5-megawatt model, has 116-foot blades [=35m] on a 212-foot [=65m] tower > > > To dissipate $2^{11}W$ one would need to use $2^{11}/1.5^{6}=133333$ such turbines. At 35m of "wind turbine space personal" (lets make if 50), one will need 67 rows of such turbines, each row 100 km in length. This will lead to a lost of a real estate strip about 3.5km in width. [Answer] # Lets work out how fast the wind is! First pass, lets try a perfectly flat world. In that case, if the atmosphere is in steady state, then each square meter of land is producing ~100,000 Newtons of air pressure vertically, which is decomposed into a 100,000 newton air pressure normal to the surface, + 500 Newtons of skin drag parallel to the surface. For this square meter of surface, $$ 500\:\mathrm{N} = F\_D = \frac12 C\_D \cdot \rho \cdot v^2 \cdot A $$ $$ C\_D \approx 0.003 $$ $$ \rho = 1.2\:\mathrm{\tfrac{kg}{m^3}} $$ $$ A = 1\:\mathrm{m^2} $$ $$\begin{align} V\_\text{surface} \approx \sqrt{\frac{500\:\mathrm{N}}{.003 \times 1.2\:\mathrm{\frac{kg}{m^3}}\cdot1\:\mathrm{m^2}}} \approx 1200\:\mathrm{mph} \end{align}$$ This provides an upper bound In general, every square meter of your world is responsible for pushing uphill on the atmosphere with $50\:\mathrm{kg}$ of force. So, if your world is covered by a crowd of unmovable people standing 1 meter apart in a grid, the wind will exert $50\:\mathrm{kg}$ on each of them, or roughly their bodyweight. So, as a lower bound, the wind whistling through this crowd will be around $120\:\mathrm{mph}$, the typical terminal velocity of a person. Of course, the winds above their heads will be significantly higher. We now have an upper bound of $1200\:\mathrm{mph}$ and a lower bound of $120\:\mathrm{mph}$. We can also go to the literature: this study <https://journals.ametsoc.org/view/journals/atsc/72/12/jas-d-14-0383.1.xml> ![](https://i.stack.imgur.com/L9dhK.jpg) suggests groundcover has a $C\_D$ of around 0.01, which would mean 450 mph winds. They only find $C\_D$ for wind speeds up to around 20 mph, but the trend is downwards. While this calculation is still pretty dubious, I think it's honestly a pretty good estimate for how fast the wind would be. ## How hot is the atmosphere? A lower bound to the heat input to the atmosphere is $120\:\mathrm{mph}\times 500\:\mathrm{N} = 26\:\mathrm{kW}$ per square meter. Assuming that all this energy is being radiated to space, then the stefan boltzmann law says that the world is 557 degrees celcius An upper bound to the heat input to the atmosphere is $1200\:\mathrm{mph}\times 500\:\mathrm{N} = 260\:\mathrm{kW}$ per square meter. This requires a world at 1204 degrees celcius to stay steady state by radiating to space. ## Final answer: Yorkshire is somewhere between a hurricane-force pizza oven and a supersonic blast furnace. [Answer] Quite apart from perpetual wind and a perpetual mudslide that would mash everything to a fine sludge and wear the surface and any unevenness away, there would be no way and nowhere for the sun to set or alternatively rise - how would it cross an infinite plane? Either there would be perpetual night (too cold) or there would be perpetual day (too hot). Let us assume that the sun is always in the sky. In that case, there will effectively be an infinite number of suns each above one square section of the plane. The problem with this is that each sun will not only shine on the square directly beneath it; it will also shed its light and heat on neighbouring squares. Thus there will be an overlap whereby the 'land' will receive heat from all directions. The effect will be catastrophic. This is true whether there are infinite suns and infinite squares or there is just one sun and one square - the effect will be identical. Finally, how will a sun of diameter 1.39 million kilometres, fit in a sky that is only 100 kilometres across? Answer: It won't. Even if we see only a square portion of the sun, each square of sky above us will be filled with sun - in other words, the sky will be permanently ablaze with infinite sun. [Answer] ## Exponentially growing disaster At first, air would relatively gently "roll" down the infinite slope. As the wind blows, the whole system would have more and more energy pumped in it by the portals. The faster the wind blows, more energy would be pumped in the system and the more energy is in the system, the faster would the wind blow. It turns out that the rate of change of kinetic energy would be roughly proportional to the kinetic energy itself (plus probably some constant rate of pumping the energy $P\_0$, present at the beginning): $$ \frac{dE\_k}{dt} \approx \omega E\_k + P\_0, $$ where $\omega$ is just some constant which would be greater for greater slopes. Perhaps $E\_k$ on the RHS should be raised to some power, but this will not change the solution much, which would be roughly $$ E\_k(t) \approx \frac{P\_0}\omega \left(e^{\omega t} - 1 \right) $$ The problem is that this situation grows **exponentially** from the initial $E(0)=0$. Even for the gentlest slopes, the exponential growth will still happen, although it will take more time to reach the disastrous levels, but it will still be inevitable. At first, only some wind will start to blow. The wind will blow faster and faster, with nothing to stop it because the energy is only pumped into the system. Sure, some of it is lost due to friction, but that will only cause a constantly growing rise in temperature, which might be insignificant at first, but it will also grow exponentially. As the wind speeds continue to grow, the wind will tear everything on the landscape and eventually the landscape itself. Strong wind will turn into combination of wind and violent ever accelerating landslides and sooner or later everything this initially pristine landscape was made out of will be rolling down the slope ridiculously fast. The temperature of that disastrous chaos will also grow, so at some point it would turn into plasma, later perhaps even into something more exotic like quark-gluon plasma and eventually even the structure of the spacetime itself might get affected and everything may turn into some sort of singularity. **tl;dr**: Everything would be completely destroyed. ]
[Question] [ If humanity decided right now that they wanted to become a space empire and colonize the entire solar system would they be able to do it? One of the biggest problems with theoretically colonizing Mars is lack of funding and lack of fuel. Assuming that all of Earth, suddenly and universally, agreed to focus solely on colonizing the solar system (this includes Mars, all moons, all Lagrange points and ships to defend it all), would the Earth have enough fuel to accomplish this? For clarification I am asking if all the fuel on Earth is enough to travel around an empire the size of the solar system. [Answer] **It's not the fuel or even energy. Just money.** There's no shortage of the components of rocket fuel. It takes energy to convert them into rocket fuel but we have that in plenty. If money were no object we could build solar or nuclear power facilities to generate as much rocket fuel as we want. The primary thing stopping our expansion into the solar system is the cost of launch. When NASA was launching shuttles it cost $10,000 to launch a pound of cargo into orbit. Once you're in orbit it's pretty smooth sailing (it takes months to get anywhere but a gentle thrust will do and that does not take an insane amount of fuel) there are all kinds of low reaction-mass propulsion systems * Ion drives * The new EM drive which nobody can explain but which seems to work * Solar sails sound dumb but work fine So lets work on the Cost of launch. My favorite quote from one of the scrappy new rocketry pioneers was: > > Rockets are built by hand by people with phds > > > so: * Reusable rockets (Spacex has successfully landed first stage rockets 4 times) * Cheaper rocket assembly (this should happen naturally now that commercial spaceflight is taking off) * More seat of the pants design decisions (NASA's engineering is triple redundant which is great but we can accept more risk and move faster, cheaper and ultimately get better results) Armadillo aerospace is the poster boy. I believe Carmack once diagnosed a problem wrote a fix and pushed the patch to a rocket in mid-flight. Alternate launch methods * High G launch with a space gun (bad for humans, fine for water dirt, steel rods) * Of course space elevators I suspect the first one will get blown to crap. I mean seriously imagine you're a terrorist that thing is going to look like the biggest target in the world. Reduce the number and weight of things you need to launch: Raw materials food water/air Sustainability: Ultimately you'll want to bootstrap mining and manufacture in space. (this is probably the point when you know you can colonize the solar system) Sustaining life Food production in space Water harvesting in space Waypoints would really help (imagine how boring the martian had been if there had been a habitable terrarium and emergency shuttle in orbit before anyone went down to the surface) [Answer] As a common rocket fuel is Hydrogen and Oxygen, Earth definitely has enough fuel given the large quantities of water present. <https://en.wikipedia.org/wiki/Ocean> Given any electrical source, Hydrogen and Oxygen can be separated and stored as cryogenic rocket fuels. <https://en.wikipedia.org/wiki/Electrolysis_of_water> This would require a large amount of energy, but given the motivation it could be done. [Answer] The term "fuel" is actually very nonspecific. If I decide that NERVA derivative engines are the way to go, then the bottleneck is how much Uranium or Plutonium fuel I can access for the rocket motors, while using Kerosene and LOX has a different set of bottlenecks. Laser thermal launchers like Liek Myrabo's [Lightcraft](http://www.lightcrafttechnologies.com/technology.html) concept is different altogether, now the limiting factor is electrical energy to power the launch lasers. Going to non rocket forms of launch like a space elevator or a [Lofstrom Loop](http://launchloop.com) is a different technology and a different set of issues. What is really needed is a definition of what the ultimate bottleneck is, and that is energy. The Earth receives something like 175 Petawatts of insolation during aa year, which is more than sufficient energy to create a space empire, or indeed [anything at all](http://www.centauri-dreams.org/?p=35917) that we want, and once we escape from Earth, the amount of energy we can collect is limited only by the annual energy output of the Sun. So the first step of all is to ensure that we can efficiently access and manipulate the energy that we receive from the Sun, and then put it to good use. It is possible tat in the far future, we might even consider something like this: <http://nextbigfuture.com/2016/02/physics-phd-reader-of-nextbigfuture.html> [Answer] Nevermind fuel, how about all the advanced composite materials needed to build the spaceships? Unless we find another source within our solar system, or accept that we will be getting around using solar sails, and taking years and years to get anywhere, no, humanity will not expand across the solar system. [Answer] More than enough. If we were to start to colonize the Solar system, we've got an entire star's worth of energy to tap, and nearly a planet's worth of material in the [Asteroid Belt](https://en.wikipedia.org/wiki/Asteroid_belt) to mine. The only things we really need earthbound resources for are getting a few loads of people and equipment out of our gravity well, and we are doing that fairly regularly today. Additionally, there are energy resources we have here on earth we are only just beginning to figure out how to tap. There have been studies of using [nuclear (fission) propulsion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) (whose main drawback appears to be popular fission-phobia). If/when we get Nuclear Fusion worked out, then we'd have access to an order of magnitude more energy output than that. And that's before you bother to get out of our gravity well and start mining our star and/or other local solar system sources for material. There has even been some thought into trying to get more power than that via matter-antimatter drives, but we've currently got no driving need to spend the resources required to work out how to do it. If you're postulating that we suddenly would have that driving need, then more exotic solutions like that suddenly become a possibility. [Answer] Probably not. But that's not as bad as it sounds: the main incentive to go build a space empire is precisely to access new resources. So the question becomes: do we collectively have enough resources on Earth (energy and materials) to access new resources to keep pushing the boundaries? And this time the answer is probably yes. Note: the answer could be different in twenty or thirty years. there's a minimum resources investment to get those extraterrestrial resources. [Answer] You're asking the wrong question. In order to get a payload out of Earth's gravity well, you need pretty hefty amounts of propulsion. *At the moment* the only reliable way of achieving this is by rockets, which yes, require fairly vast amounts of a limited resource (fuel) to make the trip. This may not be sustainable. Once you're out of the gravity well, you can generally get by with much smaller amounts of propulsion by substituting good math, physics, and some patience. A better question might be "**What technologies would need to be developed for Earth to become a solar empire?**" to which the first answer would be "a better way of moving heavy stuff from surface to orbit, preferably one that doesn't require setting off barely controlled explosions." and work your way back from there. [Answer] You need fuel only to move out of the atmosphere not to move in space, so yes probably the fuel is enough to colonize a new planet but not to move too many people from this planet, cause more people make rockets heavier which results in consuming more fuel. But technically yes if you send ships with everything needed to survive and maybe 20-50 people per ship it would be enough to colonyze the entire solar system [Answer] In addition to the ocean, which is full of hydrogen and oxygen, we also have a giant fusion reactor already operating at the center of the solar system, and enormous reserves of hydrogen in multiple gas giants. There is absolutely no shortage of fuel available. We just have to decide to take advantage of it, and to continue to improve our engineering so that it is cost-effective to do so. [Answer] Just develop effective nano robots with self-replicating ability and put them on ships people've already sent all around Solar system. Then manage them to gather more resources and build colonies with climate suitable for people. Mankind need just more knowledge, not energy. Mankind is a quite stupid mind who doesn't know that Earth is round for a few thousand years. And after some similar discovering, people become so proud about their abilities, so most of them consider proven that God does not exist. Epic idiots. People need knowledge, not brute force energy. [Answer] The biggest unknown aspect to colonizing the solar system is radiation and gravity. What are the long term effects of 50% gravity? 33%? Can a human survive to reproductive age being born in an environment with higher background radiation than earth? We don't know. Only the men who went to the moon have ever been outside the magnetosphere so that is like 2 dozen examples for a week at a time. What are the health effects at 30 years? For reference, If humans can live on surfaces with 30% or more of earth's gravity, that limits colonization to Venus, Mars and Mercury and none of the moons. If we can't live outside a magnetosphere, that eliminates the above planets and limits us to space stations in Earth orbit, near Ganymede and Callisto (the inner Jovian moons have very high radiation levels originating from Jupiter), within close orbit of Saturn, Uranus and Neptune. ]
[Question] [ Is there a scientifically plausible way for a habitable world to have a sun that undergoes a regular, dramatic, and easily observable change? One comparable in visual impact to an event like a solar eclipse or a full moon? Such a change might affect: * Color. * Light and heat output. * Visible texture and shape. * Solar effects on the terrestrial climate, winds, magnetic field, etc. The change doesn't neccesarrily have to come from the sun itself. An atmospheric effect would be fine for example. It's more about what it looks like from below. My goal here is to create a world in which the sun cycles in a way that promotes feelings of intense religious fixation; inspiring dread, awe, submission, etc. So, just as one example, an ideal effect might be if the sun turned dark red for one month every few years, and somehow caused windstorms on the surface of the world, before fading back to normal. As I don't have the knowledge to guess at the limits of the plausible, I've intentionally made this question a bit wide. Any kind of solar event that accomplishes the aesthetic goal could be very helpful. [Answer] ## Your world has a very long rotational cycle Consider our moon. It rotates about its axis remarkably slowly, taking around 28 days to complete one full day/night cycle. That means 336-hour days and 336-hour nights; dawn becomes a big event, a time of celebration and renewal, a time for weddings and preparations for the day ahead. Sunset becomes a dark and forboding time, a time to batten down the hatches, gather in your people, and eke out your resources until the light can return... ## Your world orbits a gas giant For a less extreme result, your world could orbit a gas giant planet like Jupiter, and experience regular, very long eclipses. Give your planet a fairly wide orbit and offset it from the ecliptic to make the eclipses of varying frequency and duration. The population would see the heavens as a perpetual struggle between the glory of the light and the domination of the dark, with the gas giant clearly visible even in the daytime sky. The gas giant might be seen as the devil holding the people in thrall. ## There is an active supervolcano A supervolcano that regularly burped out a few hundred square kilometers of ash could throw clouds of debris up into the atmosphere, changing the colour and strength of the sun until they settle out. The sacrifice of virgins would, of course, be required to return the sun to its normal colour and brightness. ## A comet swarm There's a star out there in the galaxy called KIC 8462852, and it's *weird*. Observation of the star by the Kepler space telescope has detected a series of sudden and dramatic drops in the star's brightness - much greater than would be caused by a planetary transit. One of the hypotheses is that there is a 'swarm' of comets passing between us and the star, blocking out a huge amount of the light. For our purposes, a swarm of comets is a possibility, or there could have been a recent collision between two planets in the system, leaving a huge cloud of debris sunward of our planet. Either of these possibilities would result in semi-regular dimming of the star as our planet passed through the shadow of the swarm/debris. The colour of the star could change as well, depending on the density and makeup of the debris cloud. As a bonus effect, your planet would have a lot of meteor activity, allowing for fun things like cities destroyed by sudden impacts, regular fireballs streaking across the sky, and other fun stellar fireworks. ## Magic The sun is alive. It is sentient, and it is *angry*. It watches these pathetic ants crawling on the surface of the world, and when it sees something it doesn't like, it does something about it. It may deprive the world of life-giving light until the appropriate sacrifices have been made; it may burn blazingly hot until the one that offended it has been identified and staked out in a desert somewhere to be burned to a crisp. [Answer] # Have a companion star that orbits the same star The easiest way to accomplish something like this is to simply have a binary companion star. [Here](https://worldbuilding.stackexchange.com/questions/78720/is-this-circumbinary-planet-set-up-in-a-stable-manner/80627#80627) is an answer where I show a stable orbit for a binary companion inside the orbit of a habitable planet. In this scenario, there would be one main sun with a relatively fixed strength. However, there would be a companion star which would vary in brightness. For that question, the companion star would vary from brightest to dimmest by several orders of magnitude every 2 months or so. The key impact of this is that when the companion star is closest, it will significantly extend the length of the day into a long twilight in either morning or night; while at its farthest it would have almost no effect on daylight time. # Have the planet orbit two stars [Here](https://worldbuilding.stackexchange.com/questions/62948/season-cycle-that-would-occur-on-a-habitable-planet-that-orbits-two-suns?noredirect=1&lq=1) is an answer where I show the seasonal solar intensity of a planet that has a figure eight orbit around two stars. The result would be that the planet would move from orbiting one sun to the other every year or so. In this situation, the stars themselves could have different characteristics (different colors, for example). Also, depending on the luminosity of the the suns, one could turn the planet into a sweltering jungle for part of the year, and the other, cooler star could turn the planet into a frozen taiga...sort of mega-seasons. Also, during certain parts of the year, both suns will be almost equidistant from the planet...if they are equally bright then there is no more nighttime on the planet. In fact by altering the planet's rotational parameters, you could cause a year to be a complex cycle of all-day and all-night at different points of the year. This is probably the better explanation for something truly awe-inspiring. [Answer] You could put your world around a [variable star](https://en.wikipedia.org/wiki/Variable_star). In variable stars, the actual radiation output changes in quantity and sometimes in type as well. There is a layman's article that discusses some of the implications with respect to habitation, written from the point of view of using variables in *Traveller*, at <http://www.freelancetraveller.com/features/science/variables.html> [Answer] It isn't necessarily very regular, but small (between 0.09 and 0.40 solar masses) red dwarf stars can have very strong flares (which periodically really increase luminosity) and huge starspots that can cut the energy output dramatically for long periods of time. From [solstation.com](http://www.solstation.com/stars/pc10rds.htm): > > Many dim, red (M) dwarf stars exhibit unusually violent flare activity > for their size and brightness. These flare stars are actually common > because red dwarfs appear to make up more than two-thirds of all stars > in our galaxy. Although flares do occur on our Sun every so often, the > amount of energy released in a Solar flare is small compared to the > total amount of energy that Sol produces. However, a flare the size of > a Solar flare occurring on a red dwarf star (such as UV Ceti) that is > more than ten thousand times dimmer than our Sun, Sol, would emit > about as much or more light as the red dwarf does normally. > > > [Proxima Centuri](http://adsabs.harvard.edu/abs/2007AAS...21110311J) seems to have a 6.5 year cycle involving both flare activity and (dark) starspots. From the [Habitability of Red Dwarf Systems](https://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems), starspots can lower light output by 40% for long periods of time. Note that this behavior tends to be worse in dimmer red dwarves (< 0.2 solar mass) and not as pronounced in larger ones. [Answer] One of the possibilities is that some extremely advanced interplanetary civilization is harvesting the energy from your sun. Thousands, possibly millions, years ago they've built a [stellar engine](https://en.wikipedia.org/wiki/Stellar_engine) around your sun, most probably [Dyson swarm](https://en.wikipedia.org/wiki/Dyson_sphere#Dyson_swarm). Example image from Wikipedia: [![enter image description here](https://i.stack.imgur.com/Wokil.jpg)](https://i.stack.imgur.com/Wokil.jpg) Some of the components are closer to the sun than your planet, some of them are much further away. This creates a seemingly random pattern of astronomical events. Sun can be fully or partially blocked for large periods of time. Some parts of the night sky will be affected as well. The orbiting patterns of the power-harvesting components are under control of their creators. Hopefully, they take into account the life on one of the planets. [Answer] An [aurora](https://en.wikipedia.org/wiki/Aurora) is caused by solar radiation interfering with Earth's magnetosphere, exciting charged particles in the atmosphere that then give off photons as they relax to their equilibrium state. Cycles or phases in the output of electrically-charged solar particles (solar wind) could create a suitably dramatic visual effect in the sky, although you may not be able to see it during the day (unless it was very intense). [Answer] Your planet could have one or more moons that regular eclipse the sun. As each moon passes between the planet and the sun, the sun will go through phases. Of course we get this phenomenon on Earth, as the Moon occasionally eclipses the Sun. It's pretty rare on Earth, but one could imagine an orbit for the Moon that would make it more common. Namely, an orbit that is in precisely the same plane as the planet's orbit around its sun. If there are multiple moons in similar orbits, it would be more common still. [Answer] A an object of 1/4 the mass of their sun (like a smaller star, giant comet, etc.) could have fallen into the sun a hundred years ago. The star might still be undulating irregularly, like a blob of water in microgravity. <https://www.youtube.com/watch?v=ntQ7qGilqZE&t=20s> (Hopefully some astrophysicist reading this can clarify whether this would completely destroy the planetary system, due to gravitational effects when the foreign object arrived, or whether the planets could survive. I'm sure orbits would be perturbed! Perhaps if the object approached from the "back side" of the sun relative to the planet in the story, the planet would still be able to orbit, though the orbit would be more elliptical, causing more extreme seasons.) [Answer] **WARNING! MANY POSSIBLE ANSWERS ARE DEADLY DANGEROUS TO THE NATIVES OF YOUR PLANET AND COULD WIPE THEM OUT!** You will want to select answers that don't threaten to kill off the natives of the planet. That means a lack of drastic changes in the amount of radiation the planet receives from the sun. The planet's axis of rotation will probably be tilted away from exactly right angles to the plane of its orbit. That will give the planet seasons like Earth has - Earth's axis is tilted 23 degrees from exactly a right angle to the plane of its orbit. Thus at different seasons the sunlight hits a spot on Earth at different angles and with different intensities, resulting in different temperatures. Even though the amount of sunlight reaching Earth is almost exactly the same year round, Earth's axial tilt causes drastic seasonal temperature changes in various parts of Earth. In temperate and arctic regions the temperature changes with the seasons are drastic enough that plant and animals life and humans have to adapt to it in order to survive. The severity of your planet's seasonal temperature changes will depend on its axial tilt which you have not specified. If the planet's sun was significantly variable the temperature changes added to the seasonal temperature changes could wipe out all life. If the planet's orbit around it's sun was significantly elliptical instead of almost circular the temperature changes added to the seasonal temperature changes could wipe out all life. Volcanic eruptions could change the appearance of the planet's sun drastically as they often have on Earth. They have often caused widespread crop failures and famines and one tens of thousands of years ago might have killed almost every human alive at the time. Even larger and deadlier eruptions are in the geological record. Stars suitable for having habitable planets are all main sequence stars and have a relatively small range of mass and luminosity. I suggest that you try something less drastic than most of the suggestions. The eyes of the natives may be more sensitive to bright light than human eyes. Maybe they are usually active at night, and don't go out in the day more than humans go out a night. Thus they don't get good looks at the blinding sun even as much as humans do. When they go out in the day, they notice the position of the sun from the length and direction of shadows. And the sun could "change shape", and thus the shape of its shadow, if it was a double star. The planet could orbit around both stars if it was several times as far from the two stars as the separation between them. The stars would probably orbit each other with a period of a few Earth days, while the orbit of the planet around them might equal a few Earth months to a few Earth years. So over a period of Earth days or weeks, the stars would appear to move apart to a distance of maybe ten or twenty degrees of arc, and then get closer together until they passed each other and grew apart on the other side, and then came back together. And their shadows, which the natives could see, would do the same, pointing farther apart as the stars grew farther apart, and moving closer together as the stars got closer together. And maybe the planet's atmosphere would periodically change, and fill with light scattering particles, dimming the apparent brightness of the suns so the natives could look directly at them and see that they were 2 balls of light and how they moved relative to each other. Or maybe it is the opposite. Maybe the natives are active in the day, and the atmosphere is normally so overcast that they can't see the suns, merely a blob of slightly more intense light that periodically gets wider and narrower. And perhaps there is a periodic changes in the atmosphere that make it less overcast and enables them to see the two stars clearly. Another possibility is having a star that is slightly - repeat slightly - variable and a planetary orbit that is slightly - repeat slightly - elliptical, and both the variability and the orbit have the same period. So either 1) the star is brighter when the planet is closer to it, and thus the two causes of temperature differences will reinforce one another, or 2) the star is brighter when the planet is father from it, and thus the two causes of temperature difference should almost cancel each other out. And if the star's period of variability and the planet's orbit period are not exactly the same, the planet's situation will gradually change from 1) to an intermediate condition and then to 2) and back again. [Answer] *An atmospheric effect would be fine for example. It's more about what it looks like from below.* Big volcanoes eruptions spew lots of dust and gasses into the atmosphere. Seeing that, and having a year without a summer <https://en.wikipedia.org/wiki/Year_Without_a_Summer> would cause oodles of dread, awe and submission to the god who did this. [Answer] No to phases as we consider them, because phases are changes in reflation/shadow, and stars are central source of light, broadcasting in all directions. Regarding light and heat output, that's very possible. Unfortunately, those are based on the energy output of the sun, which would indicate the sun is late in it's life, soon to become a red giant. Life on that habitable world is in **serious trouble**. ]
[Question] [ The capital of the society my story revolves around is built on top of a cliff, similar to the White Cliffs of Dover (pictured below for reference). For story reasons, they settled in this location after fleeing another continent and had few options due to less than friendly neighbors. In the present, the city has expanded outwards into the mainland. They use a Gothic style of architecture, meaning a lot of stone is used in construction. In order to better utilize the ocean and maintain a port, a network of wooden scaffolds have been built into the cliff face. Small rooms are carved into the stone at certain intervals, to anchor the scaffolds, act as places for shops, storage and a stable refuge if the scaffolding begins to collapse. My question boils down to this: is the city's location practical? Would the stone in the cliff be able to support the weight of the city and would the scaffolding actually allow the city to act as an effective port? Is there anything else I might be missing? I haven't seen an example of a city like this (real or fictional), so any examples for reference would be appreciated. [![enter image description here](https://i.stack.imgur.com/FPDrP.jpg)](https://i.stack.imgur.com/FPDrP.jpg) [Answer] ## **Allow me to introduce you to Santorini** [![enter image description here](https://i.stack.imgur.com/hknb2.jpg)](https://i.stack.imgur.com/hknb2.jpg) * Santorini is a Greek Island in the Aegean Sea. * On a side note it is posited as possible the location of Atlantis. * The island used to not have a giant hole in the middle of it and was more round. The center is a volcanic caldera. **The explosion of the volcano left the inside of the eastern island looking likes this...** [![enter image description here](https://i.stack.imgur.com/V0uah.jpg)](https://i.stack.imgur.com/V0uah.jpg) [![enter image description here](https://i.stack.imgur.com/ALVb8.jpg)](https://i.stack.imgur.com/ALVb8.jpg) There are also caves carved directly into the face of the caldera but I am having trouble finding pictures of them on the googles... **To answer your questions.** 1. Is it practical? Well, practicality is situationally dependent. So you can make it practical without a doubt. Better put, it is certainly *plausible* 2. As long as you allow for cranes and other items to hoist things up the wall, it could function as a port (though it will never be as efficient as more natural ports). A couple ideas on plausibility * Geographic location. Sometimes you need a port as a way point when the full distance is too great. In that situation you work with what options you have, if in your scenario the option is an island with cliffs... * Defensible. If the threat of attack from the sea is a constant problem, be it another nation-state, pirates, vikings...being atop a cliff makes attacking the town a whole lot harder. * Point of interest. Not sure what your setting is but the island could have religious significance, importance to a king/leader, or be a tourist destination. [Answer] [![Cliff city](https://i.stack.imgur.com/W2mmV.jpg)](https://i.stack.imgur.com/W2mmV.jpg) Lots of places built into the sides of cliffs in history. Transporting people and materials would have been difficult and they used surrounding plains for their agriculture, forests for wood, animal enclosures etc,. rather than being self sufficient in their cliffs. Ireland has around 100km of (now buried under peat) stone walls which were used as animal enclosures atop a cliff. So there is nothing that stops the top being used if you can defend it. All that is necessary for a port is deep water close in and a sheltered harbour, so given that then yes, you could have a port. Here's a link with other real life examples [Click me](http://www.touropia.com/incredible-city-cliffs/) [Answer] (NOTE: I started writing this answer before @amflare posted theirs, and before @AlexP posted his comment.) The existing answers do a good job of demonstrating that you *can* build a city on the side of a cliff, so let's look at whether you *should*. The main problem you'll have is that **cliffs erode**. They will, over time, retreat inwards, eating away at your caves and creating a gap between the scaffolding and the cliff face. It's a very gradual process, and depending on the geological makeup of the cliffs, it should be gradual enough for your townsfolk to be able to keep pace with it (moving the scaffolding, digging the caves deeper, and so on). I'd like to note that the cliffs in your picture are made of limestone, which erodes *very quickly*. Cliff erosion will probably be more of a danger to the stuff *on top of* the cliff. There are numerous examples (@AlexP linked [one of them](https://en.wikipedia.org/wiki/Dunwich) in his comment) of cliffside houses that have had to be abandoned because the cliffs have eroded their way right up to the back door and the house is now about to crumble into the ocean. In your case, if a cliffside house were to collapse, the falling debris would also wipe out anything on the cliff face below it, so it's probably not a good idea to build too close to the edge - or if you do, demolish the house as thoroughly as possible before the cliff edge reaches it, otherwise you're in trouble. You'll also want some kind of coastal defences, because I imagine a city built on the side of a cliff is going to be wide open to naval bombardment. Fortunately, you can do all kinds of crazy stuff depending on your story's tech level, from Archimedes' solar mirror death ray thing to giant cannons hidden in alcoves inside the cliff face. As for the positives: it would make a great port town; it'd be very easy to defend from land-based attacks, as enemies can only come from one direction; and you'd have one hell of a nice view. [Answer] I don't know much about the White Cliffs of Dover, but I can offer some personal observations of the coastline around San Francisco. **The cliffs themselves:** When I see cliffs with nice, clean, well-defined edges, I immediately assume the cliffs are unstable. Oceans typically come with lots of strong winds and lots of sand/dust/grit in the air. These phenomonon act as natural sandblasters to the local geology, turning sharp edges into smooth, worn slopes. If a cliff edge is sharp, that says to me it has not been exposed to the ocean air long enough to get worn down. That says to me that the leading edges of the cliffs collapse so frequently, wind erosion don’t have time to have a significant effect on the edges before they fall and are replaced with new edges. The cliffs in your photo do not have a bunch of structures at their edges. This is probably because (according to weather.com) the cliffs are eroding at a rate of 8 to 12 inches per year. **Ships docking at the port:** Your ships will have a heck of a time docking at your port. Those unstable cliffs have been shedding boulders and who knows what else into the ocean for centuries. This means the ocean leading up to the cliffs have been changing a lot. There probably won’t be a lot of well-known, safe approaches to the land. Ship captains will have to stay far back from the cliffs. There won’t be many soft beaches for the rowboats to approach. Docks will have to be constantly moved around to accomidate the changing landscape. Remains of abandoned docks will litter the ocean around the beaches, causing more navigation hazards to ships. Your city is in for a LOT of upkeep work. **The city atop the cliffs:** People get upset when their houses fall into the ocean. For example, look at the Esplanade in Pacifica, California. In the 1960s, apartments were built a few hundred feet back from the cliff edge. There was a small strip of land, a community swimming pool, and a road in between the cliff edge and the apartments. In 2010, the apartments were condemned by the city. One of the back porches attached to the complex fell into the ocean. The pool and road were long gone. Many of the apartment’s residents refused to move out. They sued the city in an attempt to remain in their apartments. They claimed the city had a responsibility to protect the apartments by reinforcing the cliffs. The city had been attempting to reinforce the cliffs for years, moving giant boulders down to the narrow beach below and piling them up against the cliff edge. Boulders used in this manner are called riprap. Spoiler alert: Riprap doesn’t work. The water seeped through the gaps between boulders and continued eroding the cliff. The city tore down two of the apartment complexes. We’ll see what happens to the rest of them. In summary, your city can try anything they like, but the ocean will win this fight. The disaster will be slow-moving and a lot of people will refuse to believe it is happening. In the end, whoever owns the infrastructure immediately around the cliffs will likely experience total financial ruin. **Bibliography:** White Cliffs of Dover erosion rates: <https://weather.com/science/environment/news/england-dover-cliffs-erosion> California coastal town of Pacifica dealing with erosion: <http://www.cbsnews.com/news/sinkhole-california-pacifica-coastal-erosion/> Pacifica apartments almost falling into the ocean: <http://kron4.com/2016/03/07/pacifica-apartments-at-risk-of-falling-off-cliff-set-for-demolition/> More on Pacifica, here are a series of photos from 1972 to 2016 showing the erosion progress: <http://www.sfchronicle.com/bayarea/article/Pacifica-cliff-disaster-Photos-1972-to-today-6801897.php> The fate of the Ocean Shore Railroad, built on the cliffs in the same general area as the aforementioned Pacifica apartments: <http://www.cityofpacifica.org/about/history/ocean_shore.asp> And the fate of Devil’s Slide (a former section of California Highway 1), about 10 miles south of the apartments: <https://en.wikipedia.org/wiki/Devil%27s_Slide_(California)> [Answer] > > Is the city's location practical? > > > Well, you first need to ask "Why is it a cliff?" Keep in mind that cliffs are sheer for a reason and tend to endure a fair amount of abuse from sea and storms. So how long do you want the city to be there? > > Would the stone in the cliff be able to support the weight of the city > > > Yeeeeeeeeessssss. Technically (unless it was really soft stone). But as mentioned above, the structural support of the stone won't be be main issue here. It'll stand for the same amount of time no matter what. The obvious exception being if you riddle it with so many holes that it clearly won't stand. But assuming you are mindful, it won't be an issue. > > Would the scaffolding actually allow the city to act as an effective port? > > > The scaffolding won't work. I'll refer you to the comment above about the amount of abuse applied to the cliff face. > > Is there anything else I might be missing? > > > Not that I can think of, but I do have an idea for you. IDK what the timeline is for your story, but what you could do to mitigate many of the issues is have the city retreat back into the cliff face. Each generation tunnels back a little further. So as the cliff erodes, the city just moves further back. Obviously since the humans are doing part of the work of "eroding" this section of the cliff will erode quicker and slowly create an inlet in the landscape, which could lead to some interesting opportunities for city layout. [Answer] For a port you need a bay or other protected body of water. Or else ships caught in port by a storm will be smashed against the cliff and into docks and buildings. Many river, lake and sea ports were and are multi leveled. The docks are at the level of the water and the buildings are at various levels on gentle slopes, sheer cliffs, natural and artificial terraces, etc. etc. In Naples, for example, the buildings climb up hillsides, though not as steep as you would like. <https://www.google.com/search?q=sea+port&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjDwYfoh8DTAhUn4IMKHeJ7DnsQ_AUIBygC&biw=1280&bih=894#tbm=isch&q=italian+seaports&imgrc=yabWQsZjGWzB6M:[1]> Istambul. Again,not a steep as you asked for. <https://www.google.com/search?q=istambul&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjSx4zYicDTAhUC5CYKHZq4CCQQ_AUICCgD&biw=1280&bih=894#imgrc=A1lLVfAvIAuZKM:[1]> Santorini looks closer to what you asked for. <https://www.google.com/search?q=santorini&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwitoKiTisDTAhXG4yYKHXXkCXoQ_AUIBygC&biw=1280&bih=894[2]> Rio has mountains, but most of the buildings are in the flatlands: <https://www.google.com/search?q=rio+de+janeiro&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjRz8DcisDTAhXLwiYKHeaUAH0Q_AUICCgD&biw=1280&bih=894[3]> Dover has buildings at sea level and other on top of the cliffs. <https://www.google.com/search?q=Dover,+Kent&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi8mMHijMDTAhXERiYKHUOGB1wQ_AUICigD&biw=1280&bih=894[1]> And "seaports with cliffs" yields some interesting images. <https://www.google.com/search?q=seaports+with+cliffs&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjTpu6SjMDTAhXCWSYKHXUdCq4Q_AUIBigB&biw=1280&bih=894#imgrc=_[2]> [Answer] There could be a reason you haven't heard about cities on cliffs. The reason being those cities no longer exist. One of the examples is [Trzęsacz](https://en.wikipedia.org/wiki/Ruins_of_the_church_in_Trz%C4%99sacz) (welcome to Polish 101). It doesn't take long to notice that sea or ocean have an impact on a shoreline. Also having a port (and not a defensive castle) would require additional work for loading and unloading ships which would occupy the piers for longer time. I'm not a marine expert but I think that such coast would have been exposed to much harder, stronger waves than normal ports which are usually located in bays. So the city could get a finite amount of goods in a time window set by tides. And people would notice very quickly to go into the mainland and find other terrains more suitable than try to live on the cliff. [Answer] It is possible that the cliffs formed at an earlier point in history, then other geological changes had the cliff become a bay. You'd still worry over erosion, but not at the rate you see on a typical cliff shoreline. Make it a nice, hard stone, with the cliff forming from some type of rapid-onset natural event (earthquake, volcano, meteor impact) and you could see a city on a cliff for thousands of years. But, yes, parts of that city would be falling off every now and then, and you'd see a lot of civil engineering around preventing or responding to erosion. The scaffolding is unlikely to work; stairways and such carved into the cliff sides would be more feasible. [Answer] I'm surprised no one else has said about this...but what about cliffs that don't go into the water? I know you're showing Dover in your picture but cliffs don't have to be by the sea, it could have once been by the sea (so you get the carved out limestone and everything) but the water level could fall and leave a cliff in the middle of land but maybe with a river still to connect it to the sea. Obviously this helps avoid the erosion problem where your city ends up falling into the sea. You could carve tunnels into the stone to get you down to the bottom like in [Nottingham](http://www.nottsheritagegateway.org.uk/places/caves.htm). This would give you a lot more protection against the elements as you go down to the docks. [Answer] If you don't insist on a seaport, but the cliffs represent a choke point on a trade route, you could do worse than using [Petra, Jordan](https://en.wikipedia.org/wiki/Petra) as an example of what your city might look like. [Answer] It's a bit different as it is more a town for leisure but I thought it might be worth mentionning Sorrento in Italy near Naples at least for possible inspiration from its stairways and architecture. [![Sorrento, Italy](https://i.stack.imgur.com/epbr3.jpg)](https://i.stack.imgur.com/epbr3.jpg) As for the risks due to the location : yes, but scaffoldings or parts of the city falling in the ocean every now and then it can be a prettry nice (maybe not the perfetct word) allegory of a people ouf outcasts litterally living on the edge, struggling to develop their city falling apart almost as fast at it's being built, people living over the void wondering whose house wil be the next to sink. ]
[Question] [ If an advanced alien life form were to visit Earth, given the hypothesis that baring/showing one's teeth might be universally considered a sign of aggression -- would it make sense to avoid smiling at them? [Answer] Yes, but you've got to wonder what sort of a species they're going to be if they take it personally when you do. In your question you make the very clear assumption that baring teeth at this alien species is to be considered a sign of aggression, so you clearly know this in advance of meeting the aliens. You've also stated they're 'advanced' and I'm assuming they're spacefaring, which means that if they think we're starting a fight, they can hit back with enough force to autoclave the planet. In that context, giving them a big, cheesy grin would be akin to deliberately trying to piss off a foreign dignitary with the power to level your country. You shouldn't smile, not because it's going to do bad things, but because it's *polite*. On the other hand: these aliens are advanced. If they're coming to us, then they should be able to realise that our social norms are not going to be the same as theirs, and that some customs and behaviours that they take for granted are going to be different here. Any race that's developed enough to have spaceflight should be able to take a breath and realise 'oh, it's OK, he isn't actually trying to start a war, he's just saying hello'. If they actually do take offence, they aren't the kind of aliens we want to be associating with! I wouldn't expect us to start nuking ships in orbit if an alien ambassador descended into the White House and took a leak on the floor of the oval office. I'd expect we'd try to work out if we should do the same when we visited their houses first. I hope a more advanced race would feel the same way. **TL;DR**: Don't smile, but don't expect the aliens to go thermonuclear if you do. Of course, all of the above is based upon the predicate of the aliens actually being in any way like us. If they're just... well, alien, then it's anyone's guess. [Answer] I think smiling at aliens is a good idea, if the aliens have observed humans for a while before the contact. In that case, they are well aware of a correlation between a smile and non-aggressive behavior, and should expect us smiling. If they just have crashed and you're the first human they've ever seen, smiling is probably ok too. The aliens must realize that their cultural norms do not apply to you. Human teeth (generally) do not look too dangerous, so the aliens are likely to guess that you're not going to attack them with your teeth. [Answer] I would go with the corny phrase, "you have to be true to yourself." If you feel like smiling with them, smile with them. Human gestures are amazing things. We use them to communicate things at a velocity that our more conscious communication mechanisms cannot keep up with. These gestures are the ones that we claim allow one to "peer into the soul." It makes sense that you would want to approach smiling at an alien accordingly. If you believe it is a good idea to show these aliens that which makes us human, go for it. If you feel the need to protect that bit of humanity from the aliens, don't smile. I could see a case where one has started to smile and subconsciously realizes the alien is mimicking you, perhaps not with their mouth (do they have mouths?), but with some other set of muscle movements. You have hundreds of thousands of years of instincts bound up inside you. Are those alien muscle movements friendly or hostile? You may not get the right answer, but given that you may have a scant few milliseconds to either hide the smile smoothly under another gesture or smile broadly, it's those instincts I'd put my faith in. They're the best we've got for that sort of thing. I would, however, avoid a false smile. Either smile genuinely, or not at all. A false smile not only *doesn't* show the soul of our species, but it also bars the teeth. Now you have all the disadvantages of a smile, but none of the advantages. That's a poor trade in my book. They didn't come all the way to our uncharted backwaters of the Western Spiral to observe enamel and dentin. They made contact because they feel there's something to be gained from this contact, and it's certainly not our technology. We have found over thousands of years that humanity is something we can give freely. We should offer it, and see if they accept. *This recording was made shortly before the author was involved in an unfortunate accident involving a bull in musth. It would appear that giving the sign of the horns to a bull does not have the same effect as giving the sign of the horns at a Black Sabbath concert. Many post-historians surmise that, in retrospect, heavy metal concerts may not have been the best places to find gestures that inspire a "connection between kindred souls."* [Answer] Baring teeth is a threat in the animal kingdom because teeth are weapons. For a gorilla it is similar to brandishing a gun. However, human teeth are no longer effective weapons and so I find it unlikely that aliens would be intimidated by a show of human teeth, or even realise that they used to be weapons. Overall I would say it is a good idea to smile at aliens. If they have studied human behaviour then they will expect to see smiling as a sign of friendliness and if they haven't they are unlikely to see it as a threat. [Answer] It seems to me that any organism (or machine for that matter) capable of traversing interstellar distances will be acutely aware of the difficulties of communication (even between individuals that speak a common language, let alone between species or civilizations). Consequently I would expect them to be very forgiving when it comes to an inadvertent faux pas. Imagine the most brilliant people you know getting upset because a chimpanzee or a bonobo flipped them the middle finger, or called them a name in sign language — it just doesn't seem likely. [Answer] It depends on how much the aliens know about humans. Say, for example, that they know the anatomy of a human, but not our culture. They know that we have somewhat sharp, bony, bacteria-clad outcroppings in a cavity that we can open and close at will with some force. No matter how "alien" they are, if they are fleshy on the outside, that's threatening. If they know nothing about people, they have no idea teeth are hard. If they know that a baring of the teeth (ie, smiling) is a polite thing to do in most human cultures, no sweat. [Answer] Smiling may be misinterpreted by an alien culture - the difference between a smile and the aggressive baring of teeth might not be clear (if the latter is indeed something the aliens would assume). However, I would expect that the possibility of misunderstandings will occur to both parties, and so each side will be correspondingly cautious about reacting prematurely. When humans need to communicate *and* lack a common language, or have any other communicative difficulty, we tend to default to nonverbal interpretation (body language, crude gestures, facial expressions). These are treated as more basic, and more translatable than verbal language. This tends to be true for dealing with animals, as well as other human cultures, since body language and especially aggression and threat tend to be fairly intuitive, and reading them (for those on our own planet) are a survival mechanism. So, even though we know, *really really know*, that aliens might not share body language or nonverbal signals, we will probably be trying to fit whatever they are doing into our expectations, as they will be trying to translate our own signals. It is a survival mechanism, to try and figure out the threat level as best we can. I would expect this kind of thing to be a possible problem mostly during first contact, when both sides are trying to figure out how to communicate and if the other side is hostile or friendly. Once there is some common ground for communicating, it would make more sense to ask before taking a gesture as a threat, although miscommunications may still occur. Smiling is an easy point to pick at, since it is already close to an aggressive signal (baring one's teeth). There might be other signals that translate poorly, though - showing hands is a peaceful move for us (look, no weapons), but may be an aggressive one to a species that uses their hands to fight with directly - ironically, something that occasionally comes up in fantasy in reference to mages. Something I read a long time ago had a species try to signal non-aggression by showing their unarmored bellies - which backfired a bit, since they did so by rearing up, not rolling over, and so scared the people they were trying to communicate with. Eye contact is sometimes aggressive, something like a challenge, and sometimes a friendly connection. Crouching down might mean non-aggressively trying to seem smaller, or a prelude to pouncing. There are a *lot* of ways to misunderstand body language and gestures, even when we have previous experience to guess from - and with aliens, we won't. So where does that leave us? We should probably not try to anticipate how body language will be received, it's too hard to anticipate without more knowledge. It's probably better to act as normally as we can, and adjust our behavior depending on how it is received. We will probably also try any signals we know of from a species that looks similar to said aliens (if there are any that look even vaguely similar). Pausing, or backing away are rarely seen as aggressive moves, and moving slowly and stopping any gesture that's received poorly (or reacted to strongly) may also help diffuse tensions. Mimicking is probably also a possible avenue of communication, indicating that someone is paying attention and *wants* to communicate. As long as both sides keep the possibility of miscommunication in mind, any accidental mistranslation can probably be worked out peaceably. [Answer] (tl;dr: probably safest to not smile, but you could try to figure out a way to demonstrate first that smiling is a good thing, perhaps with some video of human interactions) This is a late answer, but others are going off in many directions with assumptions that I don't think can be made, so let's try to rein this in. Even an advanced, space-faring, extra-terrestrial race which has catalogued and studied numerous other extra-terrestrial organisms very well could view teeth baring aggressively. I would assume that you have a roughly equal chance of it going either way. The following situations have been well covered by other answers and therefore I will skip them: the visitors 1) do not assume aggression based on our teeth or 2) believe that our teeth are aggressive but also realize they might be mistaken and so carry on cautiously. These are possibilities, but these cases do not present the problem of your question, so let's move on to the opposite reaction. There are a few more cases to consider.. ## We are compared to the animals around us Among animals, showing teeth often *is* a sign of aggression. If I wolf shows me its teeth, I will likely take a defensive posture or run. If our visitors are studying the creatures of our planet, and they see "teeth = aggression" is the norm, they have no reason to assume we are any different. In fact, if you look at many real, modern documentation of supposed E.T. encounters, you will find that some people have claimed to be abducted by aliens, that the abduction-subject attempted to greet the aliens peacefully with a smile, offered hand, or a "Greetings!" only to have the aliens appear frightened and back off. That's right! We already have claims in our real history that people have encountered this exact problem; we try to greet aliens with our show of respect to have it taken offensively. I am still undecided about the whole UFO sightings and ET abductions thing, so obviously take this with a (few) grain(s) of salt. Unfortunately I have no citation link for this information since I am recalling it from TV news and science/history channel stuff from many years ago. Still, I can easily see ET study a rabbit, get bit, learn a lesson. Study a wolf or bear, see their reaction before they tear another animal apart, learn the lesson further. Then try to use the knowledge they've gained to try and communicate with humans; human then smiles - oh no they are going to try to bite us too! One more note on this case before I move on: note that we could also be misinterpreting the visitors' "offended-ness" in the same way. We smile, their eyes go wide and they jump back so we think they are offended or scared, but really in their culture wide eyes are a sign of "I'm paying extra attention to you because I'm being polite" and a jump back is nothing more than "our greeting is complete, so now I'm getting out of your personal space." You never know. ## ET may have a bad temper There is no reason to assume advanced = level-headed. There are plenty of humans who will take offense at any slight cause, whether real or imagined. This does not address the teeth specifically, rather is a general case which includes the teeth issue among others. I have known many intelligent people to ignore basic wisdom. It is possible that the visitors might all be wise and level-headed, but let's not make the assumption that they are. Let's start by treating their attitudes and reactions similar to humans; no reason not to, especially since humans are extremely varied. Even if teeth are *not* taken aggressively, showing the teeth in a smile could still get negative reaction anyway. Let's go over a specific example case... I am the commander of the E.T. visitors. I have a high rank and do not tolerate anyone who does not show me the respect I deserve. My subordinates have studied your planet for decades now, ever since the first encounter at Area 51 which your government still denies (whether I know, or care, that your government kept this secret is irrelevant). Now, after going over all the paperwork flowed up to me of yet another planet containing intelligent life, I have arrived to supply an offer and paperwork for annexing Earth to the Galactic Empire. I arrive and head to the U.N. headquarters. Never mind that the previous encounters with us were done discreetly with only the U.S. government, I'm not aware since I only skimmed quickly through a tenth of the paperwork on my desk. I arrive and meet a U.N. ambassador who believes this is First Contact. I quickly state "I am Sir Arg, here to offer you the opportunity for Earth to become Galactic Empire Planet Number 3274598. Please note section 43263; you will be expected to provide us with half of your planet's entire raw resource production starting no later than 2 of your years after signing." Being the wrong governing body and having no way to translate, the U.N. ambassador has no clue what I said, smiles at me and responds "We accept you in peace." The ambassador waves. Now, take your pick, it doesn't really matter: the smile/teeth, the wave (seems more likely), whatever. I'll pick the hand wave. "How dare you give me the hand gesture that means 'Get out of my office at once, and I will call you back when I am ready to speak with you'! I retract the offer, and I will be filing a lawsuit against you for harassment since this is a violation punishable even without your admittance into our empire. The damages I will be seeking are 100Kg of antimatter for the cost of my fuel to get here and for your publish apology, punishable by death." I could give another similar response but for the teeth since that was your initial question: "How dare you suggest that you might eat me! I will be filing a grievance against this planet immediately to have your kind exterminated for your violent tendencies." Now the folks who are actually supposed to interact with the visitor arrive. "Sorry sir, please forgive these people. They did not even know you exist. We are ready to begin negotiations. (gives a hand wave, except with the arm going down toward the ground instead of up overhead since that is the proper gesture the visitor expected)". "The deal is off. (insert angry ranting here, whatever you might expect an unreasonable human to say who refuses to be civil)" ## Summary It is possible, even likely, that the visitors will be level-headed, understanding, and forgiving. The odds are still quite high that they may not be. I have had people be angry at me for something I did even when my action was an attempt at being helpful or polite, and I have had people refuse to see my action from the point of view that I conducted it with. You probably have too. I think the question is difficult to boil down to merely "should we smile at them or not?" and requires a lot more planning, including contingencies. However, if the question needs to be answered as simply and generically as possible, I would do it this way: if you can somehow demonstrate that smiling is a good thing then demonstrate and then smile at them, but if you cannot reasonably demonstrate this ahead of time it is probably safest to avoid the smile. ]
[Question] [ While smashing heavier and heavier particles together to create super heavy elements 122, 123, and 124, scientists noticed that these collisions created strange, random-looking electromagnetic waves. Upon further inspection, it turned out that these waves have patterns. The patterns repeat, but with small changes every time. After decades of research, the scientists were able to prove that this was the world's source code. By modifying and sending out the electromagnetic waves in specific patterns, they were able to do things that were thought to be physically impossible, such as teleporting objects. The scientists were able to create machines that had the capability to produce the following "commands": * **Add a force to an object** (from fractions of a nano-newton to several tera-newtons) * **Move (teleport) an object** * **Clone an object** (They can't create an object as it was too complex to figure out) * **"Delete" an object** * **Slow down or speed up time** for everything, or a specific object (but can't stop/reverse time) * **Change physical constants** (such as the gravitational constant) * **Change how an object interacts with the higgs field** (giving it more weight or less weight, even 0 weight). Mass stays the same. * and some others.1 The machines aren't terribly expensive to make (say, \$50 million) but are prohibitively expensive to operate. They are out of the reach of almost all civilians and corporations (say, \$250-500 million/hour) due to the energy cost and the several Olympic sized swimming pools of coolant required to keep the machine from overheating. Seeing that there is a huge cost to run the machine, could there be anything that it could be used for, or would the cost make the machine useless? 1*You can add additional "commands" if you think they would be helpful, but the scientists are still in their early stages. They can't revive people, they can't cure people or anything of that like. Just basic physics defying actions.* **EDIT:** The machine isn't magical. It can't create energy but instead re-distribute it from the rest of the universe. The universe's total energy won't change no matter how many times you create something/delete something. Teleporting creates small temporary wormholes, and slowing or speeding up time makes the object act as if it's going fast or slow relative to the rest of the universe. [Answer] I would start by using the machine to do the following: * Cool itself down * Generate electricity My goal here would be to generate a surplus of electricity, beyond what the machine needed to run, and to generate a surplus of coolant, beyond what the machine needed to stay cool. I'd use my coolant and electricity, of course, to run a second machine for free. With *this* machine, I'd clone up parts for a third machine, which would provide power for a fourth machine, and so on. I'd build a few thousand, maybe a few tens of thousands. I've got exponential growth if I want, with no need for raw materials or any form of input. (More food for the employees? Clone it. Want to pay them? Clone some gold). Eventually, I'd have the resources to eliminate all poverty everywhere on the globe and remove all resource scarcity everywhere. I'd make this available to everyone for free and usher in a golden age for humanity. After all of that, I'd build a huge machine, big enough to teleport a space station. Time to explore the galaxy! [Answer] That machine is WORTHWHILE. You see an earthbound cheater's machine. I see a stardrive. I don't think you understand what you truly have. We can alter c at will and induce phantom forces. We have a kraken drive with no upper limit on velocity. I need operate it for only a few seconds to change the coupling constants so the ship is no longer forced balanced internally. It will undergo continuous acceleration until changed back. The minimum cold sink mass of several Olympic swimming pools (I'll use seawater) is cheap compared to the rocket fuel required to even reach orbit. There's no reason I can't activate on the ground. [Answer] The gains would be if you can make a change that only takes some minutes of operating, but had lasting changes. If it takes minutes of the machine to properly irradiate a person so that their time is accelerated, making everything else slower in comparison, you have created a limited version of [The Flash](http://www.dccomics.com/characters/the-flash). Sure, being human he (or she) would live their remaining 50 years of active life in 25 of the world's, but you have enabled a superhuman to exist with this machine. The teleportation ability would be the first financially capable one, I suspect. > > The cost of the Falcon 9 rocket alone is 54 million, SpaceX tells Quartz, but it only burns 200,000 worth of fuel. If each rocket were reusable, and the only costs to launch a satellite were fuel and various ground support services, that would dramatically reduce the cost of getting to space. > > > That sounds like a good candidate for cloning. If you can clone 10 of them in an hour, at an operational cost of 500 mill/hr, that saves you $40 million. And the [ISS cost](https://en.wikipedia.org/wiki/International_Space_Station#Cost) to date is staggering. The defense industry would want the machine to clone itself, so they could have one for absolute weapon delivery purposes. We have countermeasures for ICBMs, but not teleportation. If what the machine is acting on does not need to be encased by the machine, then the DOD could just delete the Kremlin, or Bin Laden. Reading the question a little more, > > the world's source code... sending out the electromagnetic waves in specific patterns > > > It sounds like enclosure by the machine is not necessary. In that case, I would bet the US would be willing to double the national debt to get it, or just take it by force "in the interest of national security". A lot has changed since 9/11. Assuming you have built this in Greenland, to take advantage of the more effective cooling in a mostly frozen place, and the nearby geothermals for energy. The existence of this machine would encourage every major nation to invade. In the movie [Real Men](http://www.imdb.com/title/tt0093828/) we are negotiating with aliens to get the "really big gun" capable of destroying a world, so we can use it against the Russians. In some ways, that is how an arms race works. It doesn't matter if the scale is ridiculous, we have to have a bigger one than them. > > prohibitively expensive to operate > > > This is a subjective thought, which is why I have tried to list some interested parties that do not share it. **EDIT** Also, deleting radioactive waste that we still don't know what to do with. Not cost effective for anyone, but certainly a good test for the delete function. [Answer] The feasibility of what I’m about to consider depends on some unspecified factors (how long must the machine be running for each command, how does object size affect cost, etc). **The Users** The cost of operating this machine is definitely going to put most individual usage out of reach. There will be some exceptions for people with net worths close to and over a billion dollars, but the current usages of the machine aren’t terribly advantageous to a single person. Cloning might be an interesting one depending on its limitations, but it seems more likely that very wealthy individuals would reroute their philanthropic funding to research new commands. These people are going to be interested in figuring out how to get it to cure disease and, more importantly, expand the natural human life. Corporations could definitely use this device from a purely financial standpoint. Many corporations have annual profits measured in the billions, so shaving off a billion a year wouldn’t be unreasonable if they could increase their profits even further with the machine. The problem here is the difficulty of finding a command or series of commands that would actually net them more profit than they burn to use the device. I don’t think the existing commands would provide that benefit, but I don’t want to speculate with new commands. Governments are going to be the power users of this device, most likely for research. In practice it’s likely that all of the devices will be built and owned by governments, with corporations and private individuals renting time at the cost of operating them. **The Uses** Many of the uses that stand out seem to fall into the “for science!” category. Amazing research opportunities are opened up here, especially with the changing of the constants. After recently considering the realities of a [galactic empire without FTL travel](https://worldbuilding.stackexchange.com/questions/23513/how-could-a-galactic-empire-work), the possibility of increasing the speed of light felt very attractive. Unfortunately, that would have some [pretty bad side effects](https://worldbuilding.stackexchange.com/questions/10126/what-if-the-speed-of-light-were-100-times-higher/10200#10200). The downside to changing constants is that other values need to change in response, often with terrible consequences. There was a media uproar when people thought CERN might accidentally create a black hole… imagine what people would think when scientists start talking about changing universal constants. One other conceivable scenario, however, might be an attempt to tweak constants to make it easier to modify the universe's source code. Planetary defense against asteroids would become much simpler. Several of the commands would almost guarantee our safety from extinction-level impacts. Deletion would obviously be best (as long as we can simply give the machine coordinates). Alternatively we could add a nice amount of force to it in a particular direction, or simply teleport a spacecraft from the surface to its orbit. I think the biggest and most important use, however, will be space exploration and colonization. It would be revolutionized. Current estimates put the cost of the first mission to mars (and the effort to get to that point) close to [$100 billion](http://news.nationalgeographic.com/news/2014/04/140422-mars-mission-manned-cost-science-space/). If you redirected that money into the machine, you could get 200-400 hours of operation… teleporting people, supplies, even entire pre-built structures right to the surface of Mars. No more rockets, no more 6 month flight. Depending on the limits of teleportation functionality, we could do some amazingly crazy things. All in all, I don’t think the prices you’ve specified would render the machine useless. It would, in all likelihood, massively increase the odds of our species surviving. [Answer] How far can teleportation go, and how large can an object be? Because if the machine can, in an hour or less, transport a large manned colony to Mars soil, then it's actually cheap. Very, very cheap. Like, mind-bogglingly cheap. And we're not yet talking about distant stars... [Answer] Depends on the specifics. If they are really able to modify "world's" source code, and the energy requirements are constant (do not scale with the magnitude of the "changes"), then the experiments are really, truly dangerous – from the description I guess the modifications work on spatial regions, maybe on elementary particles but it is easy to define spatial region (or "object"). The danger of issuing the command equivalent to "delete everything within 1 megaparsec" must not be underestimated. This means it should not be used unless there are damn reliable safeguards. OTOH, establishing a research station beyond visible universe can become practical – modify space topology in that direction to shorten the distance by 14 orders of magnitude, send a spaceship, return the distance and you can experiment at a safely remote place. Just make sure the experiments do not modify the distance again... and you might do an equivalent of a segmentation fault and switch the universe off. Oops. [Answer] Given that your machine obeys the laws of thermodynamics, the entropy generated by burning the fuel that powers it (e.g. free energy like electricity is dissipated to heat) must be equal to or greater than the reduction in the entropy of the universe due to the action taken. So say we clone a 2KG block of ice, and the machine does this by taking liquid water molecules from somewhere on earth (you said that it doesn't create matter or energy, which is good). A block of ice has a lower entropy than liquid water thanks to its lower temperature. Thus, the new block of ice has lowered the entropy of the universe. Therefore we need to burn just enough fuel to raise the entropy of the universe by a corresponding amount. Unless the machine is 100% efficient (which it can't be because its not magical) it will actually take more energy than that. The energy consumed is dissipated in the machine, hence the need for cooling. But the 2KG block of ice isn't too much of a problem. But now imagine you wish to clone a fighter jet. The massive complexity of this machine (all the electronics, metal, etc) means it has a very low entropy, compared with what the entropy of all its constituent atoms in a mixed and chaotic state would be. Basically any act that 'creates new order out of chaos' is reducing universal entropy and this is not allowed by thermodynamics, even if you borrow existing matter from the universe. If you had a nearly 100% efficient manual process for building that jet (not using your machine but say using very effiient nanotech), how much energy would building that jet cost? That is the amount of energy that would immediately be dissipated in your machine when you clone the fighter jet. That is how much cooling would also be needed, and how much energy would need to be input into the machine. If you used the machine to change a physical constant or law that had an entropy reducing effect over a given volume then the energy input to the machine and the heat produced would be at least be enough to counter that entropy reduction. If any such change had far reaching effects on universal entropy it would presumably be immediately vaporised, possibly melting the ice shelf where you have it installed in Greenland or wherever. On the other hand, using the machine to fix a flaw in the wing material of the fighter jet isn't a big deal, since not that much has really changed. So I suggest there is quite a simple metric to judge the cost of using the machine - look at the 'unlikeliness' of that which it has created! [Answer] Power costs are flexible. Use the machine to clone billions of solar cells and large capacitors, teleport them to distant stars and such. Let the cells charge the capacitors, then teleport the capacitors home to power the machine to make more cells and capacitors. Rinse and repeat until the stars are producing enough power to power all your god-machines for free. Dedicate one machine to managing the power of the other machines (and use any spare machine time to make more cells to expand the capacity and recharge rate of the power network further), use all the other copies of the machine to play God until you accidentally the whole universe. Or get bored. Because that happens when you play a game with cheat codes turned on. I fear when the machine's controller decides to press the reset button. [Answer] 1) Clone some of the really big gems in the world. You say "an object" with no indication of size and you don't indicate whether things like removing weight are permanent or not. Assuming they are permanent and you can do large objects: NASA sure would love weightless spacecraft. Since the mass remains the same you still have to pay the fuel to boost it but you're not paying the fuel to boost it against gravity. That's IIRC about a 10% savings and given the brutality of the rocket equation they would pay a lot for a reusable weightless spacecraft. Also, the applying force bit you don't indicate if this simply shows up as velocity or whether it experiences acceleration. Assuming the former NASA would love such a thing in orbit to boost interplanetary craft. [Answer] I'm just looking at the clone mode. You say it can duplicate the Empire State Building in 20 minutes. It weighs 365,000 tons, or 730,000,000 pounds, and the duplication would cost 166 million (using your high value). That gives me a dollars/pound value of $4.40/lb. Gold currently costs around 16,000 dollars/lb. With this machine, you could get the cost down to around 5 dollars/lb. Not only that, but you could get the cost of *any* object down to about this range. To look at it another way, the Empire State Building cost $635 million to make in 2015 dollars. You can now duplicate it at about a quarter of the price. [Answer] Whoever has this machines and the resources to operate it, basically has absolute power. It is the ultimate weapon (just delete your enemies). It will allow you to go to space easily. It will allow you to mass produce any item (which of course will rise a few interesting questions: If you perfectly clone an original Rembrandt painting, is the clone also an original Rembrandt painting?). Basically, the first one who gets to operate this machine and has no qualms will rule the world. Once you rule the world, economic questions are, of course, moot. [Answer] # Not nearly expensive enough! Right off the hat, there are numerous actions that are worth the stated costs and many,many times more. A few trivial examples: * Deletion: A perfect way to get rid of nuclear waste! Being able to arbitrarily delete one containerful of highlevel nuclear waste is worth much, much, ***much*** more than a measly $200 million. * Cloning an object: Here's my James Webb Telescope, and 1 billion dollars. Please make 5 copies, ... * Teleporting an object: ...and teleport them to the Earth-Sun L2 point, kThanksBye. Etc. [Answer] From a more pessimistic perspective: this would absolutely be used as a weapon. Deleting the enemy's aircraft carrier is more than worth the cost. [Answer] Someone brought up thermodynamics, so expounding on that, I'd say that the cost to run is relative to the `absolute energy` required to create an item plus the inefficiency penalty. Presumably, the machine can cool itself, so it just needs an enormous amount of energy. For the `absolute energy` required for an item, think about it this way. The sun has been beating down on the planet for however many umteen million years (approximate value) and so has created an environment in which, for example, corn is relatively easy to grow. It has evolved from whatever other plants, also taking an enormous amount of energy, and the building blocks and mechanisms have also taken an enormous amount of energy. You don't care about how much energy that takes. What you care about is the amount of energy, knowing corn right now, to pop a piece of corn out of your machine. It's the same idea of popping, say, a Ford Pinto out of your machine, rather than reinventing every advance in Mechanical, Materials, and Electrical Engineering required to create a Ford Pinto. And presumably, you can even use the carbon, oxygen, hydrogen etc already present in your "reality printer." I'm not sure if that's allowed in the rules. Otherwise, you'd have to create things from whatever quarks are made of. So where it would be worthwhile to run is if you could find something to create that has a lower `absolute energy` than the `relative energy` to create it. For example, creating corn would not make sense. It is relatively easy to go to the store and get corn. Costs you very little. What it does make sense to do is create uranium or other fuels to store energy in. If someone could hack the universe that way, then those would be the conditions to run this machine under. ]
[Question] [ More or less exactly what it says on the tin. Start with a group of cavemen on prehistoric earth, discovering fire, language, wheels, etc, and walk them along the path to civilization, but with one major difference: at no point will anyone ever think of the concept of mathematical zero. How big of an obstacle would this be? Exactly how many technologies could have been invented without zero-inclusive math? You could have things like pottery, smelting, and agriculture all just fine. You might even be able to stumble into some of the more basic technologies such as the printing press or the cotton gin without any awareness of zero. But things like physics or economics would be tricky, or maybe even impossible. Exactly how much of our modern society is reliant in some way upon zero, and how far could we have gotten without it? Some details: * Base 10 doesn't exist, we're probably running off base 9 * Anything that involves math more complicated than basic algebra is completely out of the question (orbital physics, advanced electronics, etc) * Anything that could feasibly be figured out without doing the math first is fair game, but not if it has a prerequisite discovery that would require math. So for example, you could probably invent a steam engine just by knowing enough about steam pressure and how it behaves in a confined space, but you probably couldn't invent a radio. Also, it might not be a very good steam engine, because you might not be easily able to calculate the forces acting upon the metal that makes the boiler, so the whole thing might explode. * A lot of this will probably have to do with larger organizational structures. In other words, it's not inventing the train, it's making sure the train runs on time. [Answer] I think the question is not so much what we can do without zero, but how zero could remain undiscovered when humans begin to advance. One of my favourite quotes from one of my favourite contemporary mathematicians (Roger Penrose) is that it's always possible to create an equations from numbers of a given type whose answer falls beyond that type: * Positive Integers: $1-1=a$ or $1-6=a$ * All Integers: $\frac12=a $ * Rationals: $\sqrt2 =a$ * Irrationals: $\sqrt{-1}=a$ Before science, the primary driver of mathematics was commerce. How can we possibly pay off an account if there is no concept of zero? How do we record balances as fully paid? It's not so much that we couldn't advance without the concept of zero, it's more that *discovering* the [concept of zero](https://en.wikipedia.org/wiki/0#History) was always going to be a byproduct of advancement. Conceptually, it was always going to appear in mathematics because it's a necessary concept on which we build additional foundations. I'd argue that the Greeks' initial struggle with zero as a concept only pushed back western civilisation several centuries, rather than truly impeding it. When it was (re)introduced to European culture during the middle ages by the Spanish Moors, it was embraced as a necessity. That Egypt (for example) had the concept of zero nearly 2 millenia before the time of Jesus should identify it as a concept that was always inevitable. [Answer] The lack of a zero would not limit mathematics as much as you would think. Contrary to popular belief, it **is** possible to have a place-sensitive number system without any digit to represent zero. It's slightly cumbersome, but can represent any rational number except zero itself. How it works: (Note: I'm going to first give examples in base ten, and then show how the concept works equally well in base nine. I think the examples would be too hard to read otherwise.) If you eliminate zero, you just need to introduce an additional digit to represent the number base. For example, in base ten, the digit for ten could be "X". So, to count from one to twenty-five (in base ten), you would have: 1, 2, 3, 4, 5, 6, 7, 8, 9, **X**, 11, 12, 13, 14, 15, 16, 17, 18, 19, **1X**, 21, 22, 23, 24, 25 Note that "1X" represents *twenty*, even though it starts with a 1. Specifically, "1X" means you have ten ones ("X" in the ones column), and one ten ("1" in the tens column). If we grew up with this system, we would probably call this number "ten-teen" or the like. Counting from 95 to 115 would look like this: 95, 96, 97, 98, 99, **9X**, **X1**, **X2**, **X3**, **X4**, **X5**, **X6**, **X7**, **X8**, **X9**, **XX**, 111, 112, 113, 114, 115 "9X" represents one hundred ("nine tens and ten ones"), and would probably be pronounced something like "ninety-ten". You could represent non-integer values as simple fractions: $\frac{195X1}{1385X}$ You could also use a decimal point with this system, but it's a little cumbersome, because you would have to use scientific notation for numbers less than one: 1.234567 = 1.234567 2.01 = 1.X1 0.00201 = 2.01×10-3 = 1.X1×X-3 All of the above examples are in base ten, but of course you can use any number base you wish. For example, in base nine, the first twenty-three positive integers would be written as: 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25 [Answer] One way in which the concept of zero could remain undiscovered: **early availability of computers based on a floating point system.** Easiest explanation would be for the computers to come from either an alien civilization or long lost, more advanced human population. Our current standard for floating point, [IEE 754](https://en.wikipedia.org/wiki/Single-precision_floating-point_format), has a special case for zero values. The normal representation can handle numbers down to 10⁻³⁸ = 0.000 000 000 000 000 000 000 000 000 000 000 000 001. Numbers smaller than this are stored as denormal numbers, of which zero is a further special case. The lack of zero as a concept is inherent in floating point representations that try to minimize the required storage space. Because all other numbers have at least one `1` bit, the first `1` bit is not stored in the format. Note however that zero as a digit still exists. Now, if people didn't have pre-existing concept of zero, would they discover it from the computers? It seems likely that at least for a while, they'd just consider anything that small insignificant to discuss, and the difference between 10⁻³⁸ and 0 would be lost on them. --- With this background, how far could they advance? I'd say they could manage even complex calculations fine, by delegating them to the machine. There would be a lack of interest in developing manual computation techniques when computers do it so much faster. However, deep research into mathematics would cause zero to be discovered eventually. Thus any technology that requires deep knowledge of mathematics or physics to **construct** would be ruled out, though like computers, they could operate it if they got it ready-made. ]
[Question] [ What are the conditions that determine the types of buildings that will be dominant in a city (e.g. skyscrapers, several-story buildings, houses, etc.)? I guess these conditions include history (how old the city is), location, whether it becomes a trade/business center, etc. If I try to take example from the real world, I seem to not be able to determine what leads to e.g. a city with lots of skyscrapers. Seismic activity and climate seem to have little to do with this, considering cities like Tokyo, San Francisco, Sydney and New York. It looks there is not a big cultural factor, because most of the cities with a lot tall buildings are in North America and eastern Asia (but not Europe). Obviously, when the space is not enough buildings will tend to be taller (e.g. Hong Kong). There seems like in North America more eastern cities have larger areas with several-story buildings, while most western cities have a downtown with skyscrapers and houses everywhere else. I would suppose that older cities will have less very tall buildings, because there is usually less free space for such buildings and making skyscrapers was not possible until the XX century. My other guess is that the development of the tertiary sector (services) will favor gathering people more densely. It appears that there are so many factors that it's hard to extract a general rule in order to determine what is plausable. [Answer] Economics determines the need for skyscrapers and geology determines how high they can go. The growth of skyscrapers was driven by the desire of corporations to house their staffs in close proximity to the financial hub (The harbour in NYC, railing stock yards in Chicago, for example). The rising demand for limited amounts of land made it imperative to pack as much office space into a small footprint, hence skyscrapers. Geology makes the other part of the equation. Skyscrapers need a solid footing, so if the bedrock is close to the surface, building the foundation is easy. IF the bedrock is deep, then much more expensive foundations need to be built, or a much shorter skyscraper has to be built. The New York city skyline can be used to gauge to depth of the [bedrock](http://andromeda.rutgers.edu/%7Ejmbarr/skyscrapers/bedrockJuly2010.pdf): [![enter image description here](https://i.stack.imgur.com/EViJK.jpg)](https://i.stack.imgur.com/EViJK.jpg) Now since the need to have lots of office workers packed together is no longer a driving condition behind business, the need to build skyscrapers has become much lower. Modern corporations tend to create a "business campus" instead of a tower, and most modern towers tend to be "prestige projects". Modern technology also means that considerations like the bedrock depth can be circumvented; the Burj Khalifa only exists because the UAE has ridiculous amounts of money to spend and could afford to inject millions of cubic metres of grout into the sand to "build" the foundation for the monster. [![Burj Khalifa](https://i.stack.imgur.com/aIV5t.jpg)](https://i.stack.imgur.com/aIV5t.jpg) [Answer] **The general rule is economics.** Cheap space usually will get low buildings. Low buildings cost less. If any building is done at all. Expensive space will get higher buildings. Why? Yield and demand. High yield means that you can afford to invest a lot of money. High demand means that it is possible to create a lot of flooring and still sell or rent it out. The centre of large cities is where you find both. And this is where you find skyscrapers, as well. The cities with the strongest economy will have the [tallest buildings](http://www.citylab.com/design/2012/08/there-limit-how-tall-buildings-can-get/2963/) because this is where the largest spending and earning power is. That being said, there are regulations as well which usually will [limit the height](http://www.citylab.com/housing/2016/06/should-dublin-build-higher/485078/) a building can have. Sometimes bad underground will lead to foundation problems which either keeps buildings lower or will require larger investment when creating high rises. This last factor does not have a major effect as these days [geotechnical engineering](https://en.wikipedia.org/wiki/Geotechnical_engineering#Foundations) allows for buildings above 100 meters in height even on the worst soil. The [London Shard](http://eandt.theiet.org/magazine/2011/09/vertical-city.cfm) is a nice example. References: <http://www.popularmechanics.com/technology/design/g1705/21-tallest-buildings-in-the-world/> <http://www.citylab.com/housing/2016/06/should-dublin-build-higher/485078/> <https://en.wikipedia.org/wiki/Geotechnical_engineering#Foundations> <http://eandt.theiet.org/magazine/2011/09/vertical-city.cfm> [Answer] I agree with @Bookeater that basically economic is the main factor on the average height of the building. The cost of tall building VS the cost of space. However, while this is the major factor, I would also like to add that there were also some other factor affecting the height of the building. One famous example is the building height limitation in Kowloon City disctrict of Hong Kong before 1997. Height limitation is set as there was an airport nearby and the building cannot be too tall or it would crash with the landing planes. It was once a famous sight seeing place to have planes feel like flying right above your head, but now the limitation is gone when the airport is moved to other place in 1997. During Qing dynasty in ancient China, buildings in Beijing cannot be taller than the tallest building in the palace. The height limitation is set as the emperor thinks that he should be the greatest and having a taller building then the palace is a humiliation. So sometimes money and technology is not the only limitation to the height of the building. [Answer] One factor is purely cosmetic. Take Washington DC. Washington DC is an old city, at least in America. Its not that they can’t build skyscrapers, it is just that DC limits the height of buildings, as not to detract from the monuments. There are plenty of skyscrapers literally right next to DC in Maryland in Virginia. [Answer] I'd say the two determining factors are profitability and cost, resources can be imported, population affects land value but a large population will not in of itself cause tall buildings. Location is a factor but only insofar as it affects cost, building tall earthquake resistant buildings is expensive. Nobody builds a skyscraper just for the sake of it, unless perhaps they're filthy rich and conceited and even then the construction of the skyscraper has turned a profit because the skyscraper itself is what's being sold. But normally a skyscraper is built to take advantage of high land value, the more expensive it is to rent office space or rent/buy apartments in the area the more money can be spent on the construction of the skyscraper and the more profitable a larger building will be. [Answer] So, no one here has really mentioned materials and construction technology. I did some quick googling to see if the internet had anything readily available. I found [this](http://www.citylab.com/design/2012/08/there-limit-how-tall-buildings-can-get/2963/) Its focused primarily on current technology and states that a building with a footprint like the Burj Khalifa (which looks similar to a 'Y') could be constructed at least to the height of Mt. Everest, most likely significantly taller. The two considerations the article has for practical limits that haven't been addressed are: 1.Human comfort (some people might not be comfortable being over 1 km in the air and looking out a window) 2.Elevators/Transport Technology (moving large amounts of people up and down in an efficient manner is hard and gets harder with more floors) Another concern expressed is that (in general) as the building gets taller, the base gets wider (like a mountain). If this is a solid building, this leads to large amounts of the building having no access to natural light. If you wanted to do research on the heights of buildings in various cities on Earth, I think you could check out the [Council on Tall Buildings and Urban Habitat](http://www.ctbuh.org/) One final note - I grew up in San Diego and I know the downtown there has had a height restriction for a long time due to the fact that the airport is downtown. So the existence of some other infrastructure may limit the height of buildings as well. [Answer] Here ya go, in ascending order of importance; * **Location** Like you said Seismic activity is an important factor, but not as much as you think, California is right on the fault line, but you still see skyscrapers. Though an area no where near the fault line but on unstable ground is unlikely to have them. * **Resources** Even if an area has a massive population, if they lack resources then they cannot build skyscrapers. * **Population** This is *the* most important factor. A city with a large population is extremely likely to have skyscrapers, if the above conditions are met. [Answer] Supplementary answer. Yes, economics decides. But an underlying question is why do people want to cluster in the centre of a large city rather than spreading out over a wider area of cheaper low-rise offices? Especially if the city is on a plain with no geographic constraint on spreading? The answer is almost certainly a desire to get more people within walking distance of each other than is possible with low-rise. Historically, decisions of great financial or political import need rapid on call access to a wide pool of skills, and face to face meetings between the participants. Telephones did not suffice to obviate this. Face to face is felt necessary to judge conviction and sincerity and to build trust. But in the 21st century, will high-definition video conferencing suffice? The jury is out. It may be that the latest city centre skyscrapers will be the last, as obsolete as the ostentatiously attractive stone facades of the administrative centres of the 18th and 19th century imperial capitals. If so, important city centres of the 22nd century may be largely virtual constructs! [Answer] Well theoretically if you'll have enough or an unlimited base area there are no limits for the height of a building. For example you could build in a pyramid form, as high as you like, as long as you have enough material, time and workers etc.. As in reality one rarely has unlimited base area, rarely enough time or material the most important limitation would be the pressure resistance of the used material. Because wind and storms may play a role and also... An other issue is the weight of the building, so it might sink at a certain level, if the underground isn't strong enough. Beside all of this a skyscraper must also be able to lift more than itself. Some specialists say that it is (actually) possible to build a building which might reach 1.5 km (twice as high as the actual highest building on earth [Burj Khalifa](https://en.wikipedia.org/wiki/Burj_Khalifa)), but then one needs to question the need or use of that? ecological and environmental Issues etc. --- On the other hand I don't think that geology plays a minor role, as I remember that in one of the documentaries I watched on TV in the 90's there was a problem due to the underground of the skyscrapers in [Frankfurt am Main](https://en.wikipedia.org/wiki/List_of_tallest_buildings_in_Frankfurt), so in cases they need to add some to add some levels on a special side to prevent some of them to loose it balance. But unfortunately I couldn't find any backup for this. [Answer] You build your imaginary world and ask others about how tall your buildings are going to be? Ok, I will tell you about an ideal world (ideal means an optimal real world rather than crazy, wasteful, imaginary one). In real world [we need density to save resources](https://sustainability.stackexchange.com/a/4551/3357) and enhance the labor separation. You save the energy, communication roads, pipes, transportaion, everything by factor of tens if compare with urban sprawl and make the dense city is the only sustainable solution. It is like 3D routing in silicon chip building: it is much faster and more efficient when you do not scatter the resources over the wide areas but place them all into one small chip, as dense as possible. It is even suffers of overheating because of excess of waste heat. You won't need any heaters in the Northern countries, which try to urban sprawl after american life style in the countries like Estonia today, if you populate people densely enough. Now, consider the extremes. One one hand, you have everything flat and tool long roads and communications. It is an urpan sprawl and the ultimate inefficiency and waste of resources. Now, consider you pack everything into a one tall building. This will suffer from the same problem. You actually lose in density when have one single skyscraper. There must be an optimum in the middle where density (and efficiency) is maximal. It is either a cube or a sphere, the object which has the maximal volume with minimal surface area. Consider an ideal city, which is a single building with all shops, manufacturing and residential areas inside. If you have N people, you will pack them into say N\*M square meter building (M square meters for each). Let's have 2 meter floors. This means that the volume is going to be 2\*N\*M cubic meter building. Take a cubic root of that number to compute the length, width and height of your building. The height, that you asked for, will be equal to the horizontal size of your building. It makes no sense to make too tall and slim buildings. Your city must be just as high as it is wide. ]
[Question] [ Alternatively what eye properties can be modified to give the feeling of living on a flat, but infinite plane rather than being on a really tiny planet? [![model of two buildings on a tiny planet](https://i.stack.imgur.com/xVXf3.png)](https://i.stack.imgur.com/xVXf3.png) Edit (16 hours after posting): Thank you for all the answers so far- lots of great explanations, suggestions and inspiration! More context: I'm making a looping 2D animation, where camera is traveling through imaginary city and I want viewers to think that what they are looking at is just a 5 point perspective (fisheye lens). My approach is to first model that city in 3D on a sphere to avoid duplication and make camera looping easier - unfortunately this means that I have double the roundness - 1 from ultra wide lens, and the other from the fact that it's a small planet. That's where I decided to ask here what else could be done from a world building point of view to partially combat the latter. [Answer] With the right optical effects it could be quite small. Some predictions about the planet Venus (from I think the 1960s) suggested that the high concentration of CO2 plus the predicted variation in atmospheric density with depth would be such that, if you looked horizontally along the surface of Venus, then the light would be continuously refracted along a circular path of approximately the same diameter as the surface of the planet. Assume such an exotic atmosphere exists with refraction radius r on a planet of radius R. If r>R (or r -ve) then the planet looks 'spherical' like the earth does from sea-level. For example, the horizon appears to be a tiny bit below horizontal and ships appear to drop below the horizon as they move away. (If r >>R or -ve, that accentuates the effect to make the horizon appear closer/lower and the planet appear smaller). If r<R then the planetary surface would appear to be bowl-like. So, for example the horizon would appear a small distance above horizontal and you could see distant cities from 'above'. If r=R then the world would appear flat. The horizon would be exactly horizontal and ships moving away would remain in perpendicular view until they faded into the obscurity resulting from atmospheric absorption. The world wouldn't look like an 'infinite' plane though, as if the atmosphere was clear enough to see 'forever' then you could observe the back of your own head in the distance. [![enter image description here](https://i.stack.imgur.com/IjbcJ.png)](https://i.stack.imgur.com/IjbcJ.png) [Answer] ### Assuming nothing is more than 1.8m above the surface; Radius of 606km This assumes: * Your human-sized observers have human eyes. * Every human eye stays at or below 1.8m altitude at all times. * No-one ever compares shadows in different places on the planet. Or compares the stars. * No-one ever builds anything taller than 1.8m high. So - the human eye at 20/20 vision is [accurate to about 1/60th of a degree at 20ft](http://www.cctvinstitute.com.br/our-eyes-cameras-and-lenses--part-2.html#:%7E:text=At%20minimum%20angle%20permitted%20by,is%20%2C%20equivalent%20to%202200%20pixels.): [![enter image description here](https://i.stack.imgur.com/n0X9t.png)](https://i.stack.imgur.com/n0X9t.png) The "20ft" (6.1m) is where the eye muscles that focus your eye for near vision relax - it's just "anything greater than 6.1m has a 1/60 degree accuracy". So we're trying to find the radius of the circle made by the intersection of two points anywhere along these two lines (which become tangents), where the angle between them is 0.016 degrees: [![enter image description here](https://i.stack.imgur.com/xxYW3.png)](https://i.stack.imgur.com/xxYW3.png) Having not done geometry for 2 decades, I messed around with some diagrams for several minutes before giving up and plugging it into FreeCAD's sketching tool. Which promptly failed to solve it in all sorts of crazy ways relating to floating point accuracy that I find very interesting but nobody else will. Experimentation and spoon-feeding the solver eventually gave me the answer that given a radius of 606km, and a requirement that no eye ever gets 1.8m above sea level, the world will always appear flat within the human eyes vertical resolution. Even if they invent lasers to precisely mark where the horizon "should" be, they won't be able to detect it. If they only have people 1.8m high and walk around and look at each other, they still won't be able to tell, as fellow humans will be less than 1/60th of a degree when they disappear over the horizon. --- ### How to calculate something more realistic from this - ie. Lets add buildings! Because trig of really small numbers can be simplified to pass-through functions, you can scale the radius and the feature height linearly (within reason). So if you're largest ship is 18m tall, to not notice something fishy when it sails off, the planet needs to have a radius of 6060km. Same if you have a building 18m high and start walking away from it. If the largest structure is 360m above the spheres surface, then the planet needs to be 12120km in radius for a human not notice it shrinking over the horizon. [Answer] # Limit the range of vision! A.K.A. **Just add Fog**! A planet appears flat if the local area is flat, and the horizon does not obviously subtend less than 180 degrees. Example:For a normal human, the distance of the horizon on Earth is about 5km, and the subtended angle is 0.1 degrees less than 180 = 179.9 degrees, and the Earth appears completely flat. But if your maximum vision range never exceeds about 2km, you could stare all day and not notice the horizon's curvature. Not the easily visible effects, such as a ship "sinking" below the horizon as it sail away. Before the from is obvious, the object is out of sight range! As long as the maximum visible range is less than the distance at which curvature is detectable, that curvature becomes invisible to the human eye. I suspect you could take this to the extreme where your planet is only about 1km in radius (curvature visible at 50m), but if the fog limits your vision to 30m, you will be oblivious!! [Answer] An infinitely distant horizon is not visible as such, because of atmospheric scattering. The farthest humans can see, even on dry days in high deserts (which have the clearest skies there are), the practical limit for seeing from one mountain to the next is at most about 150 miles, at least according to historical US weather service reports from Arizona and New Mexico. Near the coasts, or on humid days, maximum clear air visibility is a lot less. On Mars it would be significantly farther, since the atmosphere there is much thinner (though that has lots of other consequences). You could use that distance and the horizon formula to calculate the radius necessary to cause the horizon to be at least that far away, but that only works if you can limit how high any observer can climb or fly. Consider the example of a ship with a tall mast. Anyone who watches one sail away over the horizon sees it **sink down** as it moves farther away, disappearing from bottom to top while still of appreciable apparent size. This is proof the oceans of actual earth are curved, not flat, because they are hiding *only the bottom* of all distant ships, exactly as a hill does. On a truly flat world, the ship would keep getting smaller until it all got too tiny to see at all, but your last glimpse would still see the ship all the way from bottom to top. On a world curved the other way, as on the inside of a cylinder or sphere, you could look over distant mountains to see valleys and oceans on the other side, if the air were clear enough or the curvature sufficiently steep. [Answer] **If the world has topography, pretty small.** For a casual observer, one of the simplest methods of proving the earth's roundness is to watch a ship disappear over the horizon, and to note that the bottom of the ship disappears before the top. The reason this example is always conducted with a ship and not some other vehicle is because the ocean is very big and very flat. Watching someone walk over the horizon in hilly terrain just means that they've crested a hill, and is not itself evidence of the earth's curvature. If there are no large flat areas on the planet, it won't be possible to notice the curvature by watching someone travel over the horizon. You could probably figure it out if you're able to catalogue mountain heights and calculate that the angles of how distant mountains get obscured don't quite work out, but it won't be nearly as obvious as on a perfectly spherical planet. I'm not sure exactly how small you could go before the curvature becomes obvious (it'll depend on height and closeness of the mountains), but since mountains ruin the horizon trick on earth, you can certainly go smaller than the size of our current planet. ]
[Question] [ On an alternative Earth live the people of Tcelonia. One of their founding myths goes that, in the dawn of times, when they were under the menace of being attacked by an enemy population, for an entire month the night sky of the entire planet remained as bright as under the full moon, frustrating all the attempts of a surprise attack of the enemy who, at the end, gave up an left. Since then, continues the myth, the favor of the gods has never left Tcelonia, which thrived and prospered. What natural event can reasonably explain the characteristics of the phenomenon? * Night sky as bright as when the full moon shines * Duration of one month * Spanning the entire dark side of the planet * No severe and adverse effects on life A single event is preferred, however I am also open to combination of more events leading to the same result. The less the events, the better. [Answer] Supernova. A [type II-P supernova](https://en.m.wikipedia.org/wiki/Type_II_supernova) maintains a fairly constant brightness for several months, and one at an appropriate distance (something like 500 light years) will be as bright as the full Moon for that time period. It will need to be on the opposite side of your planet from its own star, as seen from where the planet is in its orbit. [Betelgeuse](https://en.m.wikipedia.org/wiki/Betelgeuse) will do the same for the Earth, some time in the next million years. At that distance, it will not have any adverse effects on the planet or its biosphere — the light will be all that’s noticeable. [Answer] A volcano may have erupted that sent a lot of fine ash onto the upper atmosphere. However, unlike the volcanoes on Earth and due to a different chemical makeup, this volcano's ash did not keep sunlight from coming in. It also refracted light reasonably well, and by night the air over the terminator and towards the night side refracted and reflected a significant amount of sunlight back to the planet. A bystander at the equator at midnight would see a fully dark sky atop their head, but the horizon would have an eerily beautiful [Belt of Venus](https://en.wikipedia.org/wiki/Belt_of_Venus) that would shine as bright as the full moon. After a month the ash dissipated. Cue to end of times cults arising whenever that volcano goes off again. [Answer] **Aurora.** [![aurora](https://i.stack.imgur.com/kLjKE.jpg)](https://i.stack.imgur.com/kLjKE.jpg) <https://photographynewsblog.wordpress.com/2012/05/01/aurora-borealis-bright-ccanada/> > > The aurora borealis (northern lights) form when charged particles > emitted from the sun during a solar flare penetrate the earth's > magnetic shield and collide with atoms and molecules in our > atmosphere. These collisions result in countless little bursts of > light, called photons, which make up the aurora... > > > The aurora borealis most commonly occur between 60°-75° latitude, but > during great geomagnetic storms the auroral oval expands equatorially > and can reach 30° latitude or further. > > > <https://www.aurorahunter.com/what-causes-the-northern-lights.html> The aurora borealis can light the sky as bright as a moonlit night. I have seen it. In your world, as in ours, exceptionally bright aurorae happen during solar storms. [Answer] Another sun passed by the solar system and disappeared into the black void again. You only need 'moon brightness' so it can be far enough away to not present any danger (it will be farther away than our sun so tidal effects are less). You'd have to calculate the actual distance for the appropriate brightness, but you can vary the intrinsic luminosity, so that gives you enough variation. And if the distance is such that it passes through the outer edges of the solar system and rips something away, who cares. The brightness will not rise abruptly, but given enough speed, you can make a period of a month with 'significant' light plausible. The sun will have to pass on the side of earth diametrically opposed to the sun, but that also is possible. [Answer] If the **solar system encountered a homogeneous debris field with just the right size of rocks**, that were big enough to not be pushed away by the sun's bow shock, and small enough to not get sucked into Jupiter and to definitely burn up in our atmosphere... then yeah ;) [Answer] There's a nearby black hole that has no companion so it's normally pretty quiet. Something wandered by and got sucked in--not a direct hit but it came close enough it was shredded and now the black hole is very active while it eats the stuff that got trapped in the accretion disk. As there is no ongoing source of mass the disk will in time be eaten and the light will fade away. ]
[Question] [ We all at some point in our childhoods thought that the moon is made out of cheese. As such, I thought: under what circumstances can a planetary surface form in such a manner that it is edible (and ideally, nourishing) for human beings? Since the idea of something like this was never (according to my knowledge) discussed in science fiction, I have decided to ask the relevant question here: * Which (realistic) (bio)chemical and geological compositions and structures of planetary surfaces (which shall be defined as "going several meters down from the ground") make them *edible* for humans, e.g. non-poisonous, at least slightly nutritious and, if possible, well-tasting? Bacterial decomposition can be ignored (unless it plays a role in the formation of such a consumable layer in your solution). It is up to you whether the underlying processes are purely chemical (and the planet, which is ideally Terran in mass and size, does not require life as such) or whether microorganisms (or other lifeforms) significantly contribute to the formation. The surface should ideally be easily harvestable by means of shovels or other simple tools. [Answer] # The big rock candy planet 1. A planet is entirely covered in oceans. 2. Microbial life develops on this planet. This microbial life gains energy by [transforming carbon dioxide into sugar](https://www.jpost.com/Business-and-Innovation/Health-and-Science/Bacteria-engineered-to-make-sugar-from-carbon-dioxide-and-feed-world-464046). 3. The ocean becomes very sugary. 4. The planet's star suddenly increases in luminosity. The planet's oceans are boiled dry and all life is extinguished. 5. The entire planet is now covered in a hard candy crust. There might be some other stuff mixed in, but none of it is too toxic and by mass it is mostly sugar. [Answer] On a planet without life fatty acids could build up, or imagine the ocean *just* before life developed, loaded with amino acids, lipids, and simple sugars. Then the planet gets yanked out of orbit or the star burns out, either way the planet freezes, and now you you have a planet covered in frozen broth. It will be a thin broth but some places may have have higher concentrations due to freeze separation (similar to making applejack). It will be a bit salty though. [![enter image description here](https://i.stack.imgur.com/hq90V.jpg)](https://i.stack.imgur.com/hq90V.jpg) [Answer] You don't have to look very far, all you need is **limestone** or **chalk**. [![enter image description here](https://i.stack.imgur.com/Mazd9.jpg)](https://i.stack.imgur.com/Mazd9.jpg) ([source](https://commons.wikimedia.org/wiki/File:Chalk_cliffs_of_Moen.jpg)) --- Limestone (or the crumbly version of it: chalk) is made primarily of calcium carbonate, CaCO3. You probably know it better as antacid: [![enter image description here](https://i.stack.imgur.com/RkJZO.jpg)](https://i.stack.imgur.com/RkJZO.jpg) This might be extremely useful if you have a candy-covered planet as suggested in one of the other answers! --- Calcium carbonate is nontoxic and easily digestable by our stomach acids. It is a rich source of calcium (obvisouly) but also other important mineral nutrients such as magnesium, occasionally iron, manganese, and phosphporus. Bottled mineral water that flowed through limestones is usually very tasty, because it absorbed all the minerals (and carbonate) from the water. The problem is that is has no energetic value since it has no organic material in it, but it's a great supplement for those minerals and to improve the taste of several things. [Answer] 1) On an ocean world 2) A simple algae evolves that stores its sugar externally in the form of long filaments. These algae like many other thrive on the surface and clump together forming films. 3) The filaments dissolve into the water. 4) As time progresses the algae grow across the planet at the same time the dissolved sugar content makes the water gelatinous and allows the algae to cover the whole surface of the planet. 5) Now that the Algae cover the surface and beneath becomes too crowded the filaments grow into the air like hair. 6) Because the oceans have been covered by the algae, less water is evaporated from the oceans resulting in less rainfall and resulting in less surface moisture and more sunlight. 7) Because of decrease surface moisture and storm systems the filaments begin to grow long and brittle. The winds whips up the filaments into balls forming a: # Complex global terrain of Cotton Candy Of course the algae dies off in places where the cotton candy accrues so much that it blocks out the sun. But then where it isn't accruing it is still growing which leads to the formation of complex terrain. At some point its possible for all the algae to be wiped out. Ps the cotton candy solves snowball Earth by acting as an insulator and trapping heat inside. [Answer] Water is nutritious so how about an ice planet for kicks you can throw in a photosynthesizing bacteria that lives on the ice that adds nutrients and flavors. It would be a snowcone planet Food is a blend of complex organic molecules. Complex organic molecules for the most part don't form naturally. There are simpler organic molecules that do form naturally but they wouldn't make for good eating. [Answer] Many soils are already edible. Clay. In fact, clay is harvested and purified as a nutritional supplement. It doesn't add nutrition but it is used in that manner...you can eat clay to help detox the body from bad foods or from toxic materials. Check out: <https://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/french-green-clay> [Answer] It would be unreasonable for the core fo the planet to be edible. Just the way planets are formed, it's not gonna happen. But an edible crust a few km thick? Sure, not a problem. Initially, cover the whole planet with a single thin mat of teeming bacteria. Differentiate that mat into layers - the photosynthesizers in the top layer, and those that eat the leavings of the top layer, while providing structure and support below, and converting the surface into minerals which get passed up. The support layers build deeper and deeper, each layer having to bear nutrients, hydration, etc to the layer below. You essentially have a giant single-planet blob of mushroom. Cut into it and the support structures must be built thicker and stronger the deeper you go. Whether it tastes of mushroom or sugar candy or processed beef or chalk doesn't matter - the whole thing is either alive, or support structure, and the vast mass of it is needed to transport nutrients from below and energy from above. There's competitive pressure to build the layer higher to compete locally for nutrients (the same pressure that exists making our forests taller), and to dig for minerals deeper and faster. So the layer of biological stuff gets deeper. It's like a tree, if trees were umbrellas and treetrunks never developed the solidity of wood so the umbrellas had to float on top of supportive goo. [Answer] [Titan](https://en.wikipedia.org/wiki/Titan_(moon)) has a hydrospheric cycle based on methane, which leads to simple carbohydrates forming naturally and depositing. With proper sedimentation you can end up with rocks composed of alcohol, sugar, caffeine or psilocin - without any biological activity. [Answer] At first there was an Earth-like planet. An evolutionary arms-race with giraffes has pushed apple trees to grow ever larger. The fruits also grew, until they reached astronomical proportions. The original planet has since then shrunk considerably, and now shares its orbit with a dozen Moon-size apples. You can land a spaceship on them and have a taste! [Answer] Earth is like that in some places. In the north and south polar regions, you can eat snow. Granted, it'd better be fresh snow from areas far from cities. It is nourishing because your body needs water, though it's a bit tasteless when compared to about anything else. In the Andes, you have dome areas where the top-most layer of the soil is pure salt. That's because millions of years ago the Andes were underwater - the mountains went up when their tectonic plate passed over another, and they are still "growing" a little every year. A lot of oceanic salt got trapped. Some of it was taken from the underground by lakes, and when the lakes dry, they form regions called *salares*. The largest one is in Bolivia: ![Salar de Uyuni](https://i.stack.imgur.com/NlfqO.jpg) > > [Salar de Uyuni](https://en.wikipedia.org/wiki/Salar_de_Uyuni) (or Salar de Tunupa) is the world's largest **salt flat**, at 10,582 square kilometers (4,086 sq mi). It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes and is at an elevation of 3,656 meters (11,995 ft) above sea level. > > > The Salar was formed as a result of transformations between several prehistoric lakes. **It is covered by a few meters of salt crust**, which has an extraordinary flatness with the average elevation variations within one meter over the entire area of the Salar. **The crust serves as a source of salt** and covers a pool of brine (...) > > > Salar de Uyuni is estimated to contain 10 billion tonnes (9.8 billion long tons; 11 billion short tons) of salt, of which less than 25,000 t is extracted annually. > > > Look at some people literally harvesting the floor for salt! ![The floor is kitchen salt!](https://i.stack.imgur.com/SBIhf.jpg) Now imagine actual Earth is the oceans dried, for whatevdr reasons. More than 75% of the planet's surface would be covered by meters of salt. ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- Closed 5 years ago. * This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). * You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). [Improve this question](/posts/113108/edit) In my story I have an every-man, lets call him Jim. Jim never finished high school, works as a night guard, and spends his time drinking beer, watching TV, surfing the internet and hanging out with his buddies. He is mysteriously transported into the paleolithic age, and accepted by a tribe as a curiosity. He doesn't have any of his technological tools with him, only his clothes. Assuming that Jim has a lot of knowledge of technologies that could be useful to his new fellow tribesman, such as bow and arrow, hide shields, metallurgy, farming etc. But he never tried to actually use any of them, his knowledge is merely theoretical from watching history documentaries and reading on the internet. What kind of things could Jim teach them, or help them develop together? The tribe technology is at later stone age level, they have wooden spears, fire, sewing tools, fish hooks. [Answer] Supposing that he can gain enough credit with the tribe, he can probably try and domesticate animals such as horses, if any are available in the area (dogs are probably out of the question in the short period - I think?), or cultivate something, since he knows it's possible. As @John pointed out, [fired pottery](http://ime.gr/chronos/01/en/nl/culture/nl_pottery.html) is a possibility, if they don't already know. This, by the way, is Jim's only real advantage - *he knows that some things are possible*. He might try and build levers and wheeled carts. Very soon he'll try some way of getting to metallurgy, but with little chance of success as he doesn't know which ores which metals come from, or how to smelt them. In short, he can probably boost the tribe through the whole Mesolithic and bring it to a late Neolithic level. I doubt he is in position to do more, or has the time. If he gets set in as a sort of archpriest, he might have some "magic" available: smoking (it was effective [in Roman days](http://www.livius.org/articles/person/eunus/)), or being able to "remember" anything for arbitrary periods after making funny scratches with charcoal on a stone wall. With time, he might start something similar to the Druidic religion. [Answer] By far the most important thing Jim can teach them is modern notions of sanitation. He will likely teach them some by example, i.e. the see him wash his hands before eating or after going to the nearest bush to relieve himself. He himself will have some notions like digging a hole to use as a bathroom receptacle, and of course the importance of never relieving yourself near a stream (or at least doing your business downstream of where people gather drinking water). Just getting them to have the latrine pit a good distance away from the camp site is probably a huge life saver. Advancing that knowledge to cleaning wounds with water, cleansing their mouths with primitive tooth brushes (peeling away the ends of twigs into a sort of brush), washing foods before eating and so on will make them more resistant to diseases, and able to carry on day to day living longer than rival tribes (having your teeth is a huge advantage in this environment). If he knows standard first aid and can improvise bandages and slings or teach the healer/shaman what to do, then the sorts of injuries that people in this environment are prone to can be treated more easily, and people brought back into the productive life of the tribe as well. Jim will also need to be a quick study, because the tribe might want to keep him as a curiosity, but unless he is handy at doing things like making rope and nets, or can quickly pick up hunting with paleolithic tools and techniques (and trust me, no one from the modern age will hold a candle to these people), he will simply be a burden to the tribe, and they will likely leave him behind as he consumes far more than he provides. [Answer] **Writing and Mathematics** Yes, these are technologies! Even if Jim hasn't finished high school, he should certainly be able to teach basic arithmetic. (Depending on his skill level, Jim might be able to teach more advanced mathematics, but it might not have many applications for a paleolithic society.) Developing a writing system for the tribe's language from scratch will be difficult, but possible, especially if he has a good grasp on language. Alternatively, he doesn't need to come up with a new writing system if he can teach the tribe his own native language. Written communication is useful anywhere that accurate memorisation would otherwise be needed- long-distance communication, complicated instructions, or recording stories are just a few examples that could be relevant to paleolithic societies. Understanding simple mathematics is also handy for calculating distances, measuring time, and so on. On their own, these technologies are useful but not game-changing. But, they make learning many other technologies significantly easier. (Side note: this answer depends on the assumption that the tribe doesn't have these things already. I believe it is unclear how developed mathematics and writing were in the paleolithic.) [Answer] There are a lot of things that Jim knows, but not well enough to be useful. For example, I doubt he knows enough about sewing to teach his new tribe the advantages of tailored clothing -- Jim has always gotten his clothes from the store, and is unlikely to know how to knit or crochet well enough to produce useful objects, especially if he can't also spin his own fibers. Badly tailored clothing will not impress people. Jim knows how to read and write, but once he learns his new tribe's language he may find that their needs for information retention and transfer are sufficiently well met by memorization. Sequoyah invented Cherokee writing in an environment that already had great complexity and sophistication, and cuneiform appears to have been invented by accountants. Probably his most useful knowledge is going to be basic public health -- not just sanitation and hygiene, but also things like vitamins. (Good luck figuring out which veggies have vitamin A and which have vitamin C, though.). Primitive cultures generally have food taboos that cover the most important cases. Agriculture is harder than it looks -- domesticating crops without lots of experience to know about pollinators, growing cycles, and soil needs will take a lot of trial and error. (This will be a lot easier if Jim can talk some locals into helping him.) So what is likely to come in handy? * simple machines like the pulley * storytelling. Even if you filter out cultural specificity, he knows a thousand hoary old stories that are suddenly fresh and new again - [Answer] There are SO MANY things that he could bring it is difficult to make a complete list. Moving objects: * Levers: it is very very simple, he knows how to do them, and it is very useful for building and moving heavy loads * Slide (meaning, sliding loads on round wooden pikes): easier ot move heavy loads * The WHEEL! Not only useful for making a cart, but also other more advanced technologies (see below) Food. He knows nothing about practical agriculture, and about growing things but... * He knows what is a plowshare and how effective it can be for farming efficiently (you can combine with the wheel of course) * Storing food efficiently (drying is known, but what about salt? He probably knows how to gather salt - it works only for coastal areas of course) And what about smoking meat and fish, maybe it is not known at this stage. * Irrigation (with the help of the wheel and archimedes screw or noria to bring water from river) Building: * I suppose he knows what is a cornerstone and how to build a arch * He knows how to break stone with wood and water, in order to produce regular stones for construction * He knows basic geometry to compute in advance the dimensions of buildings and the amount of materials needed * He knows balance of force principles in order to make things stable Energy, the wheel is back again: * Grinding wheat and other cereals * Bringing water from river or from a WELL! Hygien: * He knows that boiling water is a sure way of getting clean water * Cleaning wounds with (very) hot stone or metal part Materials: * He knows metallurgy is possible, but finding the key ore and how to make it work is much trickier * Bricks and other fired clays objects: easier to find raw material and to fine tune process to get usable end material Vehicules: * Carts if you have oxens or horses * Ships on rivers or sea: difficult to perfect, but can boost local production with what he knows is possible, such as latin sail, rudder etc. Etc.... With time and if needed (in order to track things such as debts, reserves etc.), he can also introduce basic writing and mathematics. [Answer] There is a big question of "why would they listen?" He isn't treated as a god, but a curiosity. Writing is irrelevant - a tribe meeting makes sure everyone hears what they require to know and a tribe shaman takes care still valid knowledge goes on. There is no need to write tons of stuff down. Similarly, domestication or farming, math/calendar and even hygiene have too long "return on investment" - a tribe isn't going to bother listening to a weird newcomer demanding they do new stuff when the returns will be only seen after he is dead anyway. So, I believe his development idea needs to be something tangible that reveals itself as useful fairly soon and lets him do it mostly alone. If the tribe is near the sea, shellfish (say oysters and mussels) farming would be a decent income of food in a fairly short amount of time, requiring little tools and skills to set up a rudimentary setup, which is also self-supporting. This might be enough the tribe decides to settle down near their oyster farms. A huge change in lifestyle and tons of other options follow. [Answer] **Candles** Jim could use fat from a kill, heat it with stones from the fire till it runs, and pour it into a hollowed out bone "end" or raw mud pottery cup. Even a shell of an orange or a hollowed out root vegetable or tree nut shell would do. Suspend a wick in the liquid, perhaps a few strands of cotton cloth from his clothes, and once the fat has cooled and solidified then its a candle. Maybe keeping the source of the wicks secret is his way of stopping others from duplicating his candles. Further info <https://www.instructables.com/id/Fat-Candle/> [Answer] There's probably a lot of common technologies (for us, the wheel for instance) he can teach them, possibly by accident, just by doing something without thinking. Looking at his clothes, the paleolithics will likely wonder where he got these nicely sewn clothes from, where he answers: 'Well, I bought them obviously'. Which brings me to the concept of: **currency or money**, a means of trading goods/services without immediately having to give something in return (money is basically a form of debt, exchangeable with everyone). Although bartering has existed probably for a 100.000 years, the concept of money was first developed with the onset of agriculture. With a monetary system in place you can build a more complex society, where some people will specialize in i.e. spear making, etc. in exchange for money, instead of the odd chance he can trade it for something he actually wants/needs at that very moment. This eventually leads to people being able to invest time in other pursuits then "will I be able to feed my family today", probably leading to faster technological progress. [Answer] **Magic** or at least sleight of hand. Danger here is it might get him rejected, not accepted, if its perceived badly. * The shell game * penny (rock) from behind the ear * The thing with the disconnected thumb illusion * Cat's Cradle - perhaps he learned it from family or his own kids **Physical Actions** - perhaps Jim can juggle? Bowling or catch or dodgeball or knucklebones - nothing that requires keeping score more than "one at a time" or "taking turns" **Music/Rhythm** - noone knows what kind of song or music early man had. But there's a high chance birds were singing back then and early humans might have emulated them for pleasure. They might appreciate a rendition of "Yellow Submarine", without understanding it at all. A sling might be feasible - needs some cord and a cup, and a bunch of smooth pebbles. He may not have the ability to sling it himself, but a tribe of people who live by their hands could see the benefit. --- **We're all adults here**... so what age group is your story targetted at? Jim might be boring at home, but if missionaries haven't been invented then that's new and exotic. Also there's a size differential as suggested by @Korthalion which may be proportional. Even just same-but-different a way of freshening the blood leading to genetic variety over the subsequent generations. Many cultures recognise the dangers of inbreeding in isolated groups and could value Jim just for that. ]
[Question] [ **How could a large (10,000-20,000 people) elven city hide itself from a person wandering through?** These elves can bend plants to their will and stimulate plant growth by singing, so they could live in magically altered trees. However, they need a reliable source of food and water, a place to put waste, and solutions for all the other problems cities have. What would keep the city hidden from people in the vicinity? [Answer] Some ideas for the elf city. 1. These elves are small and camouflaged, like these little people. [![enter image description here](https://i.stack.imgur.com/w14wp.jpg)](https://i.stack.imgur.com/w14wp.jpg) 2. The "city" is a cypress forest. The entire forest floor is slowly flowing water. Poop etc is not obvious because it falls in the flowing water. [![enter image description here](https://i.stack.imgur.com/R5cAE.jpg)](https://i.stack.imgur.com/R5cAE.jpg) this image found at <https://www.flickr.com/photos/siennapictures/4892726816> The elves live inside the trees which are partly hollow and up in the crowns. There are minimal if any built structures. Travel is from tree to tree, like monkeys. When we see images of the cypress forest it is open places where people can go, but you could have ground level be essentially impassable with brush, quicksand and cypress knees blocking boats. The elves can eat leaves and fruit and raise birds and bromeliads in the treetops. Maybe they eat an occasional fish or crustacean from the waters below. An acre per individual is generous - I have to think that a football field worth of trees could support one little elf. That is not much population density. 10,000 acres is 15.6 square miles or a square 4 miles on a side. 10 elves per acre is 1.5 square miles. If these are good big trees the size of mango trees that is still fine. Plus the elves can sing the "stay in fruit all year" song to them. Really this city is a bunch of elves living in a forest. Anyone entering the city would be traveling over water and would make some noise. The elves are quiet when anyone shows up. [Answer] Well, according to [this site](http://www.lovemytown.co.uk/populations/TownsTable1.asp), the town of Antrim in Northern Ireland has a population of 23,353, which is a little bit higher than your higher estimate. A quick look on Google maps suggests the town is about 6 square miles. That's a whole lot of city to hide completely. Even if you assume the houses are built of living trees someone walking through is going to notice something isn't right, and that's before we even consider where they get their food or water from or what happens to their waste. So probably the first step to hiding it is to put the city somewhere people are not likely to go. It should be far off the beaten path to reduce the chances of accidental discovery. Then you need to deter people from coming to the area at all, probably by spreading rumours and legends of the forest being haunted (which can be backed up with a bit of tree magic perhaps, some eerily shaped trees on the outskirts or people actually being attacked by trees upon entering should help support the legends) Having done this it may be better to actually spread the city out more so that any patterns among the houses/buildings etc. are less noticeable to anyone who does brave the forest. It does depend on whether the elves live in shaped trees or in houses made from trees (which would probably be a lot more obvious if they are house shaped rather than tree-shaped) too. All in all, I'd say you would have quite a bit of trouble hiding a settlement of that size completely. [Answer] As the other answers have picked up on, you have kind of provided an answer already by stating that the elves have the ability to manipulate plantlife. Provided that at least some of their woodland plants or fungi can produce something edible (to the elves), this takes care of their food supply and probably to a large extent, the way to hide their 'city', so really, this just seems to be about fleshing that out a bit? **So how about this:** The elves live largely underground, or more specifically in the partially hollow roots of trees, which if the trees are large enough, would be absolutely massive, especially with the help of the magical elves. Also, the roots of the trees could easily be linked across a vast, VAST area. There are a number of real world phenomenon that would support this as a possibility. Plants (and fungus) can and do connect in a process called grafting which can occur naturally or with human (or elf) intervention. Effectively combine these two real-world things; The roots of large trees packed closely together will become grafted: <https://academic.oup.com/treephys/article/31/6/575/1657428/Why-should-trees-have-natural-root-grafts> And a specific example of a massive colony organism joined at the roots; <https://en.wikipedia.org/wiki/Armillaria> **Specifics:** They cultivate fruits, nuts, and berries by forced growth in easy to access hidden areas in their city. They could also eat mites, fungus, decaying or damaged plant parts in a symbiotic way that benefits the plants in which they live. They have water running through pseudo-natural aqueducts (crafted by woodwork or singing, writer's choice) for both consumption and aggregation, that can be controlled entirely with gravity and simple plumbing. This could also take care of the waste problem, but why not recycle any waste? Decommission parts of the city when they have outlived their usefulness. Those decommissioned areas are used as landfill in a way that would be beneficial to their woodland home. The elves need never even see daylight. They would only risk exposure if they venture above ground for whatever uncommon reason, or if a human manages to do the reverse; but they could, barring the need for air/light/water holes, be entirely closed off, or as closed off as you feel justifies their non-interaction with humans. **Thinking about unmentioned City problems:** This solution already solves the unmentioned problem of housing vs population growth to the extent of the available forestable area, provided that they are able to expand the forest through their magical singing or stem population growth enough that the forest consistently outgrows the population (maybe easier said than done). There's the problem of fires... A very serious problem that the elves could have little control over, or perhaps they can use their abilities and waterways to topple trees and create firebreaks and controlled flooding? There's competing growth (the obvious one). Humans etc trying to expand into forests or just felling trees as a source of wood. This would be manageable with counter growth in other directions only depending on the scale of the human activities. There are a whole host of other problems that a city faces such as crime, government, etc. but nothing I can think of that would need to be handled particularly differently in this scenario vs a typical, real-world (simpler times) human city. [Answer] Probably quite easy - have you ever tried to walk off the beaten path in a dense forest? It's really hard going. So if you're on holiday and just sort of roaming, you'll tend to follow established trails. And if you're going from A to B through the forest, you'll do the same, especially with a wagon or similar. So the answer is a quite simple one - stay away from the established trails, and ensure there's enough annoying undergrowth to block people from 'straying'. Brambles are perfect for this - they grow fast, and they're irritating and tedious to hack your way through (and obvious, so you can intercept/divert). Lines of sight in dense woods aren't all that long - so all you need do is ensure the 'city' is far enough off the 'standard' trails, and have rangers to patrol and ensure no paths - or easy routes - to the city exist. And that the paths you *want* people to follow stay clear enough that they're not tempted to make their own. [Answer] They live on top of the canopy of the forest and therefore would not be visible from below. A person wandering in the area would not realize he's walking below an elven city. Looking up will only allow a glimpse of the thick canopy. Deeper to the center of the forest it will be too dark for a commoner to explore. It is fairly visible when observed from atop of mountains, but this is solved by avoiding settling near mountains. Note that the question does not require to hide the fact that elves live there. People might know the forest is where elves live and even have diplomatic relation, but they do not know exactly where the city is. [Answer] As the elves can mould the trees, they could use them for water supply. They can alter some trees to obtain water from the soil using the roots, and then liberate in the surface as (a kind of) sap. The food could be obtained through foraging and some hunting and fishing in the forest, they could breed game for feeding and defense (deer rider elves for example). Made properly, all the organical trash could be composted (again, using moulded trees as familiar compost deposit), the broken pieces of pottery (if they use, but I would favour the wood and hide recipients) could be grounded and used as construction material for some structures (roads inside the city, brick and mortar structures, and so), the metal could be melted and used again... How to hide the city? Well, you could make it inaccessible with camouflage and abrupt terrain, (maybe a forest in the top of a mesa in the middle of the forest?) if you rounded it up with bushes and very thick foliage (like Fangorn forest in LotR) this could be a first line of defense. The second one should be the mesa itself (or something like Gondolin from the Silmarillion). You can take in consideration that you can mould the roots to make room for passages under the ground, so they could live in the top of trees and use the inside of the tree to go underground using these paths carved by the roots. [Answer] If they can control plant growth, an impenetrable thicket such that a traveller would go round it, and round a bit more for the next thicket and so on would be quite a deterrent, as well as camouflage. This would combine well with *flooded forest* ideas. The outermost trees should be too small to be desirable as firewood/construction timber for the neighbours. Too twisted for timber may also help. By enhancing plant growth in nearby regions of the forest (tall, straight, fast-growing trees, plentiful fruit on easy terrain), other people wouldn't want to use the forest-city for its resources. [Answer] ## I don't think you can hide. **Temperate climate:** Among others, you need warmed dwellings and places to grow and store food. This will mean cultivated grounds. Not to mention the strange trees you have growing. There is no way someone wandering in the forest will mistake cultivated fields. **Tropical climate:** will make your food source and living a lot easier, as you can dwell in the trees for both. **But** once you start domesticating ground-dwelling creatures, like horses and sheep. Those flocks will really stand out. And we are not talking about bakeries, mills or smithies. Those need a solid footing. And fireproof. --- ## The Five Senses Every large group of creatures, humans, sheep or even wildebeests, will make itself noticed. For creatures that hunt, it will be impossible to miss. Not just for humans. **Sight:** if not the itself group is noticed, then their sleeping quarters will be different from the surroundings. Unless extremely light footed, every living thing leaves a trace. Don't forget, humans can be [extremely](http://edition.cnn.com/2012/04/17/world/africa/trackers-south-africa-bushveld/) good trackers. It is very hard to remove all traces of [habitation](https://www.yellowstonegate.com/2012/11/forests-near-yellowstone-hold-traces-of-human-habitation-for-more-than-12000-years/). **Smell and Taste:** Food, cooking and the end product of all that will smell. Even with sewers and very good waste management systems you will be able to tell the difference between a forest and a settlement. Cities just smell different from the normal forests. **Sound:** With 10K+ sentient being living together you have culture. There is talking, shouting, whispering and singing. Our modern air warning systems don't reach everyone, so I don't think you can even have them all silent when some one strange is near. Never mind kids and babies. Good luck with pets and domesticated animals. **Touch:** If trees grow faster with their singing, there is a good change their structure will be different. Maybe the trees will have a different touch to them. --- ## To hide in plain sight What we have discussed up to this point is the normal observation of an intruder. We can play with that. But there are more options. I will list some from (mostly) harmless to lethal. **Drug every intruder** by some kind of [psycho](https://en.wikipedia.org/wiki/Psilocybin_mushroom) active substance. *Magic Mist?* Let them hallucinate. Make them forget. Give them a **very bad trip**. Make sure they get back to tell the story. What ever they see, nobody will believe them. And few will try to do the same. **Enslave** every lost human. Make them blind. What you can't see you can't tell. Very hard to get back without sight. Use them (up) with hard labour you don't want to do yourself. Even if they escape, oh the horror stories they can tell. **Kill all.** All these options share one thing: stray into our forest, it will go bad for you. You know something bad is there. An unknown horror is a bigger horror than a known one. Become the bogey man. Become the thing that lurks in the shadows. Become the thing they fear. \*Note: once there are electric lights, binoculars, air balloons or airplanes, your game is up. They know you are there. If you still want to be left alone: [aggression](https://en.wikipedia.org/wiki/North_Sentinel_Island). [Answer] Solve the food problems with magic. Since they can grow plants faster and bend them to their will, there could be elven magic farms bringing in crop every week, making a small space enough to feed a lot of elves. They should be coating their wood with fireproof magic. Place the city inside a huge forest, create a huge maze with a lot of dead ends around it and let the elves use the dead ends to get inside. (E.g. caverns, dead trees and holes in the earth connected with a tunneling system.) Let them create their storage units all underground so that the city gets smaller. Elves are nature bound so I would imagine that most of their waste is organic. This can be easily turned to new earth by magic farmers. Excess earth can be used to fortify the outer wall. Water transportation could be done by roots. They create clothes out of hemp they speed-farm if needed. If the city is connected somehow to a mountain, this is where they could get metals from. The elven city can be **a lot** smaller than human cities. In war, for example, humans need maybe a sword a month for each soldier. Elves use all their life the same magic sword, so there is simply no need for big production facilities. [Answer] Assuming the person is simply wandering through the area and not searching for the elves the answer is simple: **people don't look up**. Position yourself above a crowd of people walking past and you'll rapidly notice that almost no-one looks up. This is likely to be even more true in a forest where they will need to pay attention to footing and undergrowth. All you need to do then is **position the elven city high up in the trees**. If elves like space, with wide airy dwellings, they are likely to be well spaced out and the low population density will help hide them, and keep the impact of their scat undetectable as well as dilute the impact of their farming practices. Manipulating plants means that they will grow their food at height in the trees, mostly from fruit, and supplement it with a little hunting for birds or arboreal mammals. Their excellent night sight means they light no telltale fires at night, while the noises of the forest and the dense canopy both helps hide them from view when the rare individual looks up and muffles and hides the noise they do make. Water can be collected from rainwater. [Answer] Quite easily. After all, there are still species of animals and plants only being discovered now in the Amazon - they have no magic ability either and people were actively looking. Simply have the city in a harder to reach, dense rain forest area. Clean water isn't an issue, the tree canopy can be "bent" to cover the clearings (for farming), have the areas around even denser (and away from obvious "human" transportation such as navigable rivers). Waste is like any modern-day issue, bury it or recycle it! Rain forests are huge and contain just as much above ground as below it (there are miles of caverns and underground grottos). Lots of smaller enclaves would be easier to hide than one HUGE enclave (in a rain forest environment for example) as even overflights are likely to ignore the odd bent tree area but will certainly notice a HUGE gathering of odd-looking trees. [Answer] [The Anasazi](http://www.ushistory.org/us/1b.asp), in the United States (Utah in particular) were known to have lived in cities hid by [caves](https://www.britannica.com/technology/cliff-dwelling). And depending on how well you want your city hidden it would work for you too. The issues here would be the same they faced, water, cultivation of crops and room to expand over time. This was done in our world, without magic, so depending on your world this could be a possible solution or an excellent means of using natural terrain to be improved via magic. [Answer] If, as you say, you are going Tolkienesque then he already did this. You simply enchant the trees to open or close paths so as to divert the traveler away from or around the city. If the trees can't move then the elves can prepare and maintain well-made pathways for the locals to follow and camouflage the entrances to their realm. ]
[Question] [ After the uncontested absorption of Hong Kong in 2020, China reasserted control over Formosa in 2022. In 2023 the Korean government reopened its war against its southern rebels, leading to their surrender in 2024. Despite prognostications of world war, these went largely without retaliation. Most of the Pacific nations signed treaties assuring their neutrality, and China turned its attention eastward. Nonetheless, there was a notable casualty in the brief but bitter conflict. Many of the largest [semiconductor fabrication plants](https://en.wikipedia.org/wiki/List_of_semiconductor_fabrication_plants), such as TSMC and Samsung, were in the rebel-held areas. During the fighting, the leaders of those areas identified them as too valuable to fall into enemy hands and a military and surveillance threat to future resistance. They were therefore targeted with military weapons - and clean rooms proved quite vulnerable to artillery fire. In the aftermath, China blamed the U.S. for supporting these attacks. A cold war of hacking, fires, sabotage, even "anonymous drones" ('UFOs') followed, in which plants in Dallas and Shanghai were largely incapacitated. Major users of the chips were not entirely unprepared. Western commercial interests supported the Bitcoin Bubble as a cover for panic buying of chips in advance of the conflicts. Automakers and others began to [reconsider](https://www.reuters.com/article/us-ford-motor-semiconductors/ford-to-partly-assemble-some-vehicles-idle-two-plants-due-to-global-chip-shortage-idUSKBN2BA2TP) the use of computing technology where possible. *"Reduce, reuse, recycle"* became the motto of industries with semiconductor exposure. The initial, obvious solution was simply to build more plants, with [\$37 billion](https://www.newscientist.com/article/2271918-theres-a-global-shortage-of-computer-chips-whats-causing-it/) earmarked for expansion in the U.S. alone by 2021. But with conflicts continuing to decrease production capacity, and disasters befalling producers [even in Japan](https://www.akm.com/us/en/about-us/news/information/20210122-information/), this became a very hard sell. Who would invest $10 billion in a plant that could be destroyed in a few hours by inexpensive means? The military of each country took matters into its own hands, producing chips in secret, hardened underground bunkers. But these were not designed with consumer products in mind - they were generally at a lower scale, radiation-hardened, and even when offered on the civilian market, contained "back doors" that spooked an audience that had already started, perforce, to put the Computer Age and its pall of paranoia behind them. **Your** task is to propose the best new consumer computer manufacturing industry you can, with all the knowledge available today, **provided** it does not rely on external foundries or investments of more than ten million dollars before beginning production. (You can assume several years and billions of dollars of solid R&D funding could have happened in each country between 2021 and 2025, as long as it is not invested in one place or building a specific production plant.) The technology does *not* have to be the same as what is in use now! If you can pull out something with microfluidics, aerographene networks, quantum computing via NMR of large organic chemicals ... ***etcetera*** ... that's much more fun! But low-tech *human-scale* solutions are probably best for the plot. [Answer] ## Much Smaller Wafers and Much Larger Chips Smaller wafers require smaller foundries, which should be more survivable. This will drive the foundries to older tech, so the transistors will be larger. ## Process In a nutshell, chip manufacturing is "Build a silicon wafer, put the wafer through a bunch of highly specialized machinery." All this machinery must exist in a clean room, because static, dust, etc. will damage the end product. The high cost of building a foundry is partly a function of the high precision of those machines, and partly a function of building and maintaining a clean room. ## The Change So instead of starting with a wafer the size of a serving plate (12 inch diameter) go back to the "good old days" of the 1960s, and start with a 1 inch diameter wafer. Now you get to scale down all of the other equipment! The size of your clean room should go way down, which should make it much cheaper to build and maintain. Thus the investment is less, and the destruction of your factory is less catastrophic. A smaller foundry should also be easier to protect - it's easier to bury, easier to monitor the perimeter, etc. ## But won't you need more Foundries? Yes. But that's OK - instead of building a few, very expensive photoliography setups, you build lots of cheap ones. Build factories to build your chip factories. Sure, you won't be able to keep the quality up - that's why you go with larger transistors, because the precision requirements are lower. ## End Result You'd probably end up with more expensive, less powerful chips, but you could have dozens of foundries spread across the country, each one churning out a relatively low volume of product. [Answer] I imagine you'd see a return to the computers of the 1960s and 1970s built of discrete logic chips (TTL at the time). If you still have access to modern manufacturing at the PCB and simple component level, something in the vein of retro-hobby projects like the [MOnSter 6502](https://monster6502.com/) and the [Gigatron](https://gigatron.io/), which reimplement a CPU using only logic chips. (ie. chip designs from before [VLSI](https://en.wikipedia.org/wiki/Very_Large_Scale_Integration) that are just the 1960s-state-of-the-art way to pack 3 or 4 transistors into a smaller, easier-to-wire package.) The Gigatron kit does use a RAM chip and a ROM chip, but those can be built using transistors and diodes. (and capacitors if you want dynamic RAM) They're just significantly more bulky and, since it's a hobby kit focused on making a CPU without a microprocessor, it'd be counter-productive for the Gigatron to do that. (See [Visualizing ROMs 1: Diode Matrix ROM](https://www.wintergroundfairlands.com/2013/10/visualizing-roms-1-diode-matrix-rom.html) ([Hackaday](https://hackaday.com/2013/10/18/making-a-diode-matrix-rom/)) for more on building ROM from scratch.) ...and I do hope you *do* have access to things like surface-mount transistors and pick-and-place machines or it's *guaranteed* to be cost-prohibitive as a consumer product. Even the [Apple 1](https://en.wikipedia.org/wiki/Apple_I) used the kinds of complex ICs you're trying to avoid and it was pretty pricey after inflation despite how minimal it was. In this day and age, we take for granted how high the base cost of [stored-program computing](https://en.wikipedia.org/wiki/Stored-program_computer) is. [Answer] Assuming that you want computing in the numerical sense, and don't require electronics, then you can do many things with clockwork. [Wikipedia](https://en.wikipedia.org/wiki/Mechanical_calculator#Mechanical_calculators_reach_their_zenith) gives a better summary than I can. For the general-purpose "computer" of today, you're likely to run into the same problems as Turing, Lovelace, and Babbage - too many parts. [Answer] **There are alternative technologies and, now, a strong drive to invest on them** If a main technology becomes unfeasible or too costly, then alternative technologies will become more competitive and attract more money and resources (which otherwise would be invested in the main technology). For instance, [Organic electronics](https://en.wikipedia.org/wiki/Organic_electronics) allows to create circuit from printing plastics. Obviously, ther peformance of such devices is a lot worse than semiconductor electronics, but after the destruction of silicon foundries, they will attract a lot more investments than they would if semiconductors were still feasible. After some time, organic electronics will probably not close the gap with semiconductor electronics, but will surely improve enough to be employable for computers. Probably such computers will be bulkier than our computers, but for instance they could architecturally employ some of the pros of organic electronics (eg. the lower cost), for instance focusing even more on parallel processing in order to improve their performance. [Answer] > > not rely on external foundries or investments of more than ten million dollars before beginning production. > > > Best I can do is this: ![A breadboard with some parts soldered into it](https://i.stack.imgur.com/8t1ro.jpg) Anything requiring the finesse of even 80's level electronics will require more than a couple handful million dollars nowadays. [Breadboards](https://en.wikipedia.org/wiki/Breadboard) on the other hand can be assembled from trash, and you can throw in some cheap LED's and resistors on top of it to do some computing. Sure, a simple calculator will weight a handful hundreds of grams and will be as fast as a snail... But hey, on that budget, it's this or going back to the abacus. [Answer] ## 3D Printing Integrated Circuits We can already 3D print PCBs. There are multiple companies working on 3D printing semiconductors. By nature, 3D printers are slower than dedicated manufacturers *for the same volume*, but an individual 3D printer is often cheaper and more mobile than the smallest reasonable dedicated manufacturing plant. Instead of huge manufacturing plants, you can set up mobile manufacturing trucks that set up in a dedicated location and then leave if things look like they might get messy. Since a bunch of 3D printers on the back of a semi truck is likely to produce chips cheaper than the government's super secret underground laboratories, they will likely provide you with advance warning of bombing runs aimed at locations near your trucks so that they can move vital equipment and personnel. Eventually, someone will release these 3D printers to the consumer market, decentralizing production to the point where it would be impossible for foreign powers to bomb them. Obviously, you're probably looking at more expensive computers that are less powerful for a few decades, but eventually some mega-corporation will spend a few hundred billion dollars on secret bunkers that make the US government's cry, and everything will normalize. [Answer] Believe it or not, there is actually such a thing as amateur semiconductor manufacturing. A fellow on YouTube by the name of [Sam Zeloof](https://www.youtube.com/channel/UC7E8-0Ou69hwScPW1_fQApA/videos) has made his own integrated circuits and covered the process in detail, including a clever adaptation of a DLP projector for maskless photolithography. I think he said the feature size he can get is around 10 micrometres. That's what Intel used to make the 4004 back in 1971. It's not a fast process, but it can be done at a small scale at home with the equivalent of a garage full of equipment. You could rebuild the semiconductor industry in a decentralised fashion. If anyone with a few thousand dollars for equipment and a garage to put it in can get into chip manufacture, then you could have thousands of small outfits making chips and spreading things out so much it's no longer practical to try and take them all out. Now, I'm sure that at first it wouldn't be too much better than what Sam is pulling off now, but give it a few years with companies specialising in making home-fab equipment and you could get into 486-level stuff (800nm) at home. Just look at how 3D printers have developed over the last decade. Chip-fabbing could be the new 3D Printing. Some people doing it as a hobby, others building a small business around it. A small city might have three or four fab-on-demand businesses to supply chips needed to repair stuff. Hell, you could probably find quite a few people who design chips as a hobby and leave the actual fabbing to one of their local fab-on-demand companies because they're just not interested in that side of things. Oh, and don't forget the impact of open source stuff here. You'd probably have thousands of chip designs available for download. Some might be replicas of old chips that have been reverse-engineered (eg. custom video chips from old computers or games consoles), others could be completely new designs for various uses. We kind-of have something along these lines already, but rather than being designs to etch into silicon with photolithography, they're a bit more abstract and written in languages like Verilog and VHDL, and after a translation process analogous to compiling software, usually get used to configure an FPGA, rather than making fixed-function silicon chips. [Answer] *Frame challenge* **You put the foundries underground.** 10 meters of earth are surprisingly difficult to destroy. 10 meters of stone (even soft stone), and you need military-grade weaponry to even make a dent into them. Ventilation and such will be a challenge, but again: If you invest billions, a few millions for good airflow won't change the budget much. Usually you don't even need that. A wire fence, a dirt wall and/or cheap buildings around the expensive/dangerous parts of the facility to prevent RPM attacks, and access control are what industrial Going underground is the standard solution for cheap hardening against attacks if you don't have to be mobile. This holds even for high-tech military forces, and since the assumption is that the attacks are cheap, 10 meters of dirt and a guarded gate will prevent that. (All oil facilities should have something like that. Particularly in conflict regions like Nigeria, Syria or Iraq. None of these even went underground - of course it's merely millions that blow up, not billions, so billion-dollar facilities would have roughly 1000 times the attractiveness to attackers - but also 1000 times the budget for better protection.) *Real-world examples* Any industrial facility is actually easy to destroy with bombs, particularly if the bombs are of the cruise missile variant. So everybody who ever wanted a bomb-resilient facility put them underground: Ghaddafi's chemical plants, North Korea's nuclear facilities, Nazi weapons industry during WW2. The Nazi example is particularly enlightening: They built these underground factories *during the war*, under daily and nightly bomb raids, and got them functional with little problems. (It didn't help them much, fortunately, because they were short on almost every raw material you can imagine: metal, oil, rubber.) * The foundries may not actually be the target * If the plans are somewhat more long-term, attack the equipment manufacturers. It's a damage multiplier, since you destroy the ability to build the next series of foundries. It's what we expect of the Chinese. Well, unless maybe in a heated war - then they'd follow short-term and long-term goals. (On the other hand, that's soo cliché. Plus maybe the story's circumstances don't allow long-term plans anyway.) **Let's see what fits inside the framing** The hypes of today won't make it: * Quantum computing, even if it became cheap (which won't happen before 2050 I'd say), is not a replacement for classic computing. We're roughly at the level of the Zuse machines with that: Sort-of works but it's still a looong way to go to make the technology a commodity. The next step would be software design: They're different enough that you need to invest new programming paradigms (like object-oriented or functional programming), and we needed roughly 20 years for each of these to make them sort-of work, and another 20 years to actually understand them. * Other switchable things like ferrofluids and whatnot will be as expensive as silicon to produce: Today's silicon industry is expensive because you need ridiculous purities for the wafer silicon, and ridiculous manufacturing precision (sub-wavelength!); any alternate technology will suffer from the same problem. \*\* Things that would work inside the framing\*\* * Recycling - you'll get a specialist industry but it's workable. Lots of people who will promise but just burn the reballed CPU, so workmanship will be a big topic. The problem is that you need the right chips - you can't combine all chips, so everybody who's doing the recycling will have large chip stores, and some system to find the chips that they stored three years ago. (The stores are still attackable targes, and small stores are far less useful than large ones. Plus you will need facilities for making PCBs - modern chips require multi-layer PCBs, that's not easy to manufacture either.) Now recycling still isn't very sustainable. There's going to be growing scarcity - some people will hide the despair with activity, others will openly despair, yet others will operated on the premise "we have problems but so has the enemy, and we don't need to have IT, our IT just needs to fail later than theirs". (That might be a pretty interesting plot point, and it's very easy to show instead of tell it.) * Human calculators, accountants. You know, these were a thing before we had electronic computers. In a recycling scenario, these will become more and more important. There were specialists for calculating logarithms, specialists for calculating ballistic curves, specialists for adjusting machines, so the world will be gradually shifting towards these. These have the advantage that they're easier to "program" than machines: You just tell them, train a bit, and if there's an error, you will be able to understand why and how to fix it. [Answer] To begin with, besides a guy who DIY chips in a garage [First IC :) – Sam Zeloof](http://sam.zeloof.xyz/first-ic/), on techprocesses of 70's, there is another valuable resource [The Chip History Center - The Virtual Museum of Semiconductors](https://www.chiphistory.org/) So as mentioned in the comments [The MOnSter 6502](https://monster6502.com/) a disintegrated version of actually [MOS Technology 6502](https://en.wikipedia.org/wiki/MOS_Technology_6502) chip and reading through the history of actual chip and clicking links in it that yields some results. Not a surprise that the mid-'70s was somewhat a turning point for the chips production prices and consumer-grade solutions. And that turning point was the projection of the mask instead of it necessarily touching the wafer. Equipment that did the change was [Micralign](https://en.wikipedia.org/wiki/Micralign) - it improved the life of a mask by 4 orders of magnitude from 10 to 100'000 and reduced mask-induced defects 5-6 times for chips of that time. > > **Micralign 100** > The first sale of what was now known as the Micralign 100 was in 1974 to Texas Instruments, which paid \$98,000 for the machine, equivalent to \$508,053 in 2019, about three times that of existing high-end contact aligners.[19] Sales to Intel and Raytheon followed. Intel kept their system secret, and were able to introduce new products, notably memory devices, at prices no one else could touch. The secret finally leaked out when various Intel workers left the company. > > > What looks like a more modern version of the Micralign 100, an Perkin-Elmer 300HT Micralign Mask Aligner, which can be googled and a lot of places and offers can be seen on those, used their price seems to be around \$15'000, there is some offers on ebay for 2 grand, so it seems depends on conditions and such. So as what seems to be more modern versions and with lesser working hours around $55k How the thing looks like: [![Perkin-Elmer 300HT Micralign Mask Aligner](https://i.stack.imgur.com/U6Ep0.jpg)](https://i.stack.imgur.com/U6Ep0.jpg) It is good for 4" wafer size, the other specs are it seems to be good for 1.25um tech processes. There is quite a lot of those in circulations and they are part of lab equipment as of today, old equipment. A foot print around 1.7 square meters and I would say it is compact. This sort of equipment is just part of the chain, but never the less an important one and what actually help you to "draw" the schematics on a wafer. Applying photoresists and heat ovens and etching - those also require equipment, so making masks requires equipment. But from the looks of it, you can land on somewhat early or mid 80's specs with \$10kk with used equipment or maybe new. if you scavenge for modern guts/brains for them, modern piezoelectric actuators - I guess those can be drastically improved in terms of the making of those, with technological capacities which are available today. As if replicating their old days manufacturing methods may lead to other expenses. So it is hard to tell what it may cost to produce a new unit, be it its modernized version or as in the good old days. But overall it does look like it is not impossible to be on the budget you propose for a single production node, full cycle. This kind of equipment requires a lot of manual work, this page contains how intel fab processes looked like in 80's: [An Intel Wafer Fab Cleanroom Circa 1980](https://en.wikipedia.org/wiki/Micralign) - for me it looks like a somewhat typical biological laboratory, meaning it does not look totally insane so as it already looks like they are under the ground, lol. so it may have a good touch of a modern redesign for our current production paradigm, along the general modernization, but that R&D will be smeared over all those factories you build, so... Overall, some useful keywords are: [Micralign](https://en.wikipedia.org/wiki/Micralign), [Stepper](https://en.wikipedia.org/wiki/Stepper) Results are on pair with 80's, and at least it somewhat shows that if someone throws few billions in it, it definitely can be done better than just 80's, producing relatively compact nodes of production, and 80's are the low bar. [Answer] **Farms, not plants.** [![genetically engineered cow](https://i.stack.imgur.com/WPoX1.jpg)](https://i.stack.imgur.com/WPoX1.jpg) There is already great interest in biological synthesis of semiconductor components. Semiconductor foundries are large and delicate. Life forms routinely undertake operations of comparable delicacy. <https://spectrum.ieee.org/semiconductors/materials/germs-that-build-circuits> > > By the time you read this, there's a good chance a virus has built a > transistor. Last July.. Angela Belcher make a bold prediction: within > six months, her laboratory... would have genetically engineered a > virus to coat itself in a crystalline semiconductor sheath and locate > and bridge two electrodes--thus forming the critical part of a > field-effect transistor, the kind on which most computer chips rely. > If Belcher delivers, it will dramatically illustrate biology's promise > in furthering nanotechnology, the manufacture of circuits and devices > only billionths of a meter in size. > > > Biological self-assembly, as this field of research is called, has a > compelling appeal. Living creatures produce the most complex molecular > structures known to science. Crafted over eons by natural selection, > these three-dimensional arrangements of atoms manifest a precision and > fidelity, not to mention a minuteness, far beyond the capabilities of > current technology.... In projects now under way, scientists are > using proteins and DNA, the molecule that encodes genetic data, to > construct nanometer-scale crystals of semiconductor atom by atom, bind > to precious metals, distinguish between different nanoparticles by > their electrical properties, and otherwise choreograph the arrangement > of nanoscale components. > > > ... The Army and others see a role for biological self-assembly in > fabricating future sensors, displays, and magnetic storage devices, as > well as in energy production and information processing. > > > In this near future, political instability accelerates the development of organic semiconductors synthesized by organisms. At the same time, the advent of CRISPR gene manipulation produces a revolution in drug development. Many drugs once produced in giant bioreactors can instead be produced by farm animals and excreted in milk. The animals are normal animals and the milk normal milk. The milk is processed to extract the drugs. Genetically engineered animals producing drugs is no longer fiction. <https://www.theverge.com/2016/12/3/13819482/genetically-engineered-animals-drugs-sab-cows-pharming-future> > > SAB’s cattle are just the latest example of lab-made animals > engineered to be drug factories. Last year, the US Food and Drug > Administration approved a genetically modified chicken that makes a > drug in its eggs to treat "lysosomal acid lipase deficiency" — a rare > genetic condition that prevents the body from breaking down fatty > molecules inside cells. In 2014, the FDA approved a drug collected > from the milk of lab-made rabbits to treat hereditary angioedema, a > genetic disease that causes body swelling and can be fatal. And in > 2009, the FDA approved a genetically altered goat that can make a drug > in its milk that prevents fatal blood clots. > > > These transgenic animals are promising because they could make > drug-manufacturing cheaper in the long run. Once created, the animals > can basically keep pumping out drugs at a low cost — the cost of > maintaining chickens and goats in a farm. And now that new > gene-editing techniques like CRISPR-Cas9 are making swapping and > inserting genes easier than ever, creating new animals in the lab will > be faster and cheaper. “I expect that we will see this progressing at > light speed now,” says William Muir, a professor of animal sciences at > Purdue University. “We know the technology, we know how to use it, and > we’re just waiting for, how many applications can we use it for?” > > > In your near future, organic semiconductors meet pharm animals and semiconductor synthesis moves outside. Engineered animals breed true and as a neat byprodct, the milk and eggs retain nutritional value and are still good for that after semiconductors have been processed out. The price of semiconductors falls dramatically. Semiconductor industries are no longer valuable targets. [Answer] ### China is hostile? Intel doesn't care. Look at the list of the semiconductor fabrication plants in the OP. In particular, look at Intel. Almost all of their plants are in the United States, and the ones that aren't are located in Western countries like Israel or Ireland. If China starts making chips from Taiwan and Japan non-viable in America, it won't hurt them. Heck, by knocking out so much of the competition, it might even help them! The price of the raw materials might go up and hurt their bottom line a little bit, since China currently produces [79% of the world's elemental silicon](https://www.azomining.com/Article.aspx?ArticleID=1532), but the stuff is found basically everywhere so building facilities for mining and refining it should be entirely possible. ]
[Question] [ In my fantasy world there is a large valley. At the northern end lies the 'endless desert' called the "Sea of Glass" due to its shimmering sands. Within these deserts live great wyrms that swim through the sand as if it was an ocean. The wyrms/worms would roughly have these dimensions: 4 meters high and wide and stretching to lengths between 10 to 30 meters. The 'mouth' of the beast is cylindrical however their mouth is protected by a beak that is enclosed during burrowing (making a cone shape). The worms most likely breath oxygen and would need to resurface (think about the same time as a humpback whale). Their main hunting strategy is to stalk their prey using echolocation to hear footsteps above the sand then the worm would launch its self forward and open their beak aiming to suddenly swallow and enclose their prey. These worms are pretty big critters. I'm wondering if a purely carnivorous diet would be able to sustain a worm of this size as well as possible eating habits as a bonus (ex: would it be better to eat one large meal and then sleep or would they be more like sharks and constantly on the move) Note: One animal species that does exist in this world, but not the Sahara, is a creature similar to a Bantha from *Star Wars*. They'd be furry animals comparable to yaks in size, but relating more to elephants in nature. [Answer] **Your worms are ambush predators. They very rarely move.** <https://www.bbcearth.com/blog/?article=snapping-death-worms-can-hide-undetected-for-years> [![death worm](https://i.stack.imgur.com/qACiG.jpg)](https://i.stack.imgur.com/qACiG.jpg) These giant polychaete marine worms > > (Eunice aphroditois, also known as the sand striker) > > > are real. They lurk, waiting for something to pass by in reach and then they pounce. They get big; at least 3 meters. For big predators they move so little they can go unrecognized in plain sight for many years. > > In 2013 a metre-long worm was found by staff at Maidenhead Aquatics in > Woking, Surrey, which they estimate had been living in the tank for 10 > years undetected. An even larger worm was found in 2009 at the Blue > Reef Aquarium in Newquay, which had been devouring fish and even > snapping bits of coral off the tank’s reef installation; the staff > nicknamed it “Barry”. Further afield, a 3m long worm was discovered in > a mooring raft in Japan's Seto Fishing Harbour in 2009 – one of the > largest specimens ever discovered. > > > This is how your sandwyrms work. They do not cruise around looking for prey like the worms in Dune. That would expend a colossal amount of energy. They hold very, very still, and the main movement is a quick attack and then swallowing the prey. The larger they are the less they move from place to place, and the truly big ones only move under extreme duress. They live in a desert, but this desert hosts a seasonal migration of large ungulates between their winter and summer homes. That migration is when the worms reliably feed. Feed they do - their bodies can expand to contain pretty much as many animals as they can catch, and they can catch one after another during the peak of migration. With those reserves the worms can go many years between feedings, and big ones can even metabolize their body segments and shrink in size during prolonged lean times. The ones you find cruising around out and about are the juveniles looking for a new home. Those little ones relocate often and have been known to chase down prey. One might encounter several juveniles at once which can be a bad situation. Those can definitely be trouble but are unlikely to kill you outright. Some people might dig them out and reinstall them like biologic land mines. [Answer] 4 meters high and wide and stretching to lengths between 10 to 30 meters is a huge beast. Having to burrow in the sand to move takes quite some energy, as it requires displacing a dense medium. Plus ambushing the prey is another additional effort. A carnivorous diet seems adapt to supply that much energy, however here is the issue: you state they live in a desert. Large animals in the desert are rare or even absent, and smaller animals, though present, are scattered around. For this it would be better a hunting strategy similar to whales: ingest and filter large amounts of medium (water for the whales, sand for the worms), capturing all the edible content. Additional issue: in a desert with such a massive body heat dissipation might be an issue. Therefore a more lean body might be helpful. [Answer] A carnivorous worm is not unlike a snake and we have data about what snakes eat (they're all carnivores). Giant snakes may only eat 4 to 6 times yearly. ([ref](https://en.wikivet.net/Snake_Feeding_and_Digestion)) And snakes can lower their metabolic rates, become more protein efficient, and [survive months without any food at all](https://www.livescience.com/7348-snakes-survive-months-food.html). Though [most snakes eat every 5-14 days](https://www.petmd.com/reptile/nutrition/evr_rp_what-do-snakes-eat). The largest snake in the world is the [giant anaconda](https://www.livescience.com/34444-biggest-snake-largest-snake-longest-snake.html) (Eunectes murinus). They weigh about 550 pounds (250 kilos), average 17 feet (just over 5 meters) in length, and can have a circumference of 3 feet (just under a meter, which is about 1/3 of a meter in diameter). This snake has a volume of about .44 cubic meters. Your creature has a volume of 125 to 375 cubic meters (assume 4 meters diameter and 10-30 meters in length...which is very very thick and not very wormlike, especially at shorter lengths). If volume is proportional to caloric needs, your worm would need at least 284 times the calories of a giant anaconda. It's not really proportional though, so the actual need for your worm would be less. Let's round down to 200 times. A giant anaconda can go months between meals, especially a [large meal like a deer](https://www.livescience.com/53318-anaconda-facts.html) (120 lbs. (54 kg)). If we assume a giant anaconda eats 480 pounds (218 kg) of live prey a year, this would mean something in the ballpark of 96,000 pounds (43545 kg) a year for your worm. So something in the vicinity of one of the following (or a combination): * 800 deer (or humans, average weight 120 lbs). * 60 cows (female average weight 1600 lbs). * 40 bulls (male average weight 2400 lbs). These are just estimates. I haven't found exact feeding requirements for giant snakes, we don't know how caloric needs scale up with mythical creatures, and we don't know how the caloric needs of a giant worm compare with a snake. But the order of magnitude should be right. This is pretty doable for worms in an environment with lots of prey and not a lot of competition for it. But in the desert? That is rough. What other animals are there they could eat? That is what you need to answer. If you assume herds of roving flocks, and very few worms, you're good. As for time between meals, they could rest for a long time after large meals but, given how much they have to eat (because there aren't other animals big enough to sustain them for a meal), they wouldn't rest too much. Weeks vs months. Note that sometimes giant snakes eat each other. This isn't sustainable of course but it could reduce competition and keep a worm alive another several months. [Answer] There are already some good answers here, but I want to explore an issue which hasn't been covered yet. The biggest problem you have with your worms is not their size per se; it's the fact that they are cold blooded creatures in a desert. Cold blooded animals have a metabolism that is in sync with the ambient temperature; that is to say, colder animals are more sluggish and eat less. Warmer ones are much more active and their appetites increase to match. Crocodiles for example can get away with eating as little as a couple of Kgs of meat a day, but then they spend a lot of their time in water. Sharks too would eat a lot more if they weren't in a cold environment. It's believed that a T-Rex would have eaten around half a metric tonne of meat every day. But, your worm has three issues that a T-Rex didn't have to deal with. It's literally burrowing through the sand to get anywhere (takes a lot more energy than walking), it's in a desert meaning that during the day it's very hot and it's even bigger again than the T-Rex, meaning that it doesn't make a good ambush predator; it can't leap out of the sand for instance because it would be fighting the square cube law (it jumps / carries / runs a smaller percentage of its body size as it scales up). But, is it possible? Well, your worm is going to need a lot of those Banthas you describe. That means they're likely solitary animals with massive territories to protect. That's because the desert is going to struggle to keep the water and food supplies available for large herds of Banthas or any other creature. But, that soon becomes a losing proposition as it's likely that your worm is going to spend more energy getting between creatures in the heat than it gets from the next Bantha. So, I don't think that a carnivorous worm in a desert would survive on that diet alone, no. If it did, then it would eat that huge meal all at once like a snake. In point of fact if you're going to do it, you have to end up with something that works a lot like a snake on all fronts. That's far more likely than a worm. For a start, the scales of a snake are far more likely to protect the creature from the sand leaching out the moisture through the skin and if it's truly carnivorous, you'll need a brain and eyes and the like, none of which a worm has. Especially if you're looking for something that can *catch* meat rather than surviving as a carrion eater. ]
[Question] [ I always found it interesting, and it was clearly inspiring to the soldiers, that there were drummers and fifers during the 18th and 19th centuries, playing music during *marches* *into* battle. However, my question is, would it be impractical for, say, the drummers and fifers to stay behind the main line and continue to play music when the soldiers were locked in actual combat? What are the pros and cons? This could also apply to medieval combat, combat in antiquity, et cetera. [Answer] The whole point of the drummers and fifers are FOR the march. Walking in formation requires timing and coordination. The drums helped everyone keep the beat. Now the military uses [cadences](https://en.wikipedia.org/wiki/Military_cadence). It keeps time and occupies the mind. Having 'music' during battle would be strange. Once fighting starts you won't hear it and what is its point? It's not like you want your ear buds in while trying to split your enemy from throat to groin. One of the biggest issues would be that horns were frequently used to sound battle movements and adding more noise to an already extremely loud venue (music on top of that) might make it harder to direct armies and generals would have even more noise to contend with. (I think it would be a bad idea) > > He was just a rookie trooper and he surely shook with fright, > > > He checked all his equipment and made sure his pack was tight; > > > He had to sit and listen to those awful engines roar, > > > "You ain't gonna jump no more!" > > > [Answer] ## It's probably impractical. **Pros:** * Soldiers know their flanks are clear as long as they can hear the drummers. This is a tactical and psychological boon. * The enemies are intimidated by the drumming. * Enemies may unconsciously fall into time with the beat, while friendlies are trained to avoid the predictability this leads to. * The battle fever, for more cowbell, will be cured. Allowing soldiers to focus on the battle fever, for killing. **Cons:** * Friendlies can't hear the guy running up next to them because the drumming is too loud. * Drummers might be better used as soldiers in the fight. * Friendlies may unintentionally fall into step with the drumming. * Drumming while watching your buddies fight, kill, and be killed might be too difficult. * Drummers would be called bards. Nobody wants to be a bard. [Answer] One of the main purposes of the musicians during battle was to help command the troops. The commander would stand in a place where they could view the whole battle (or as much as possible), the musicians would watch for the commander's signals, and would use different instruments or rhythms to convey the messages to advance, hold, fire, retreat, and any other pre-defined commands that the troops would know (and the enemy would not). Remember, this was in an era before radio, shouting instructions can only carry so far. [Answer] The Scots in their various wars (mostly against themselves) used bagpipes a lot to stir the troops, even during the battle (although not right on the front line once the enemy were engaged). I think the following passage answers gives both pros and cons of the practice. > > The bloodcurdling sound and swirl of the pipes boosted morale amongst > the troops and intimidated the enemy. However, unarmed and drawing > attention to themselves with their playing, pipers were always an easy > target for the enemy, no more so than during World War One when they > would lead the men 'over the top' of the trenches and into battle. The > death rate amongst pipers was extremely high: it is estimated that > around 1000 pipers died in World War One > > > <http://www.historic-uk.com/HistoryUK/HistoryofScotland/Scottish-Piper-War-Heroes/> Further reading: <http://www.nefa.net/archive/songmusicdance/pipes/war.htm> So, while these other answers tend to dismiss the idea, it's not only possible, it's got strong historical precedence. [Answer] Playing music during the battle would make it harder for troops to hear commands of their leaders, horns and trumpet calls to indicate the need to change formation, retreat etc. Then there's the need to be quiet to hear enemy attacks and movements as well. That said I believe there was a case some years ago in Iraq where tanks blared heavy metal music at the enemy in order to either challenge them into showing themselves and to frighten them, they may have also been shooting at the time (space in a tank is tight though and they may have been insulated inside from the outside noise). Remember that scene from Apocalypse now where they play music during a helicopter attack to frighten the enemy? These exceptions I raise are probably due to the one-sided nature of those battles. [Answer] **It makes sense to play music and sing shortly before the battle.** It improves morale of your troops and lowers the morale of the enemy. There is story from Czech history, that when [Hussites](https://en.wikipedia.org/wiki/Hussites) were raiding the country, one battle ended before it could even start, because the enemy did flee just after the Hussites [singing a battle song](https://www.youtube.com/watch?v=elskCac9wSI) ]
[Question] [ I was thinking about people who once told me that I must feel the rain earlier than them (I'm tall). So I thought of a world where the rain falls so slowly that the humans of different size living on it may not feel the rain at the same time. Let's set a few boundaries, because I want this world to have a similar kind of humankind (at least in size and shape, no problem if they are actually looking like lizardmen). I need an answer fitting these elements: * Most of the so called humans must be from 20cm to 2.5m tall (newborn to tall grown up) * The size of the planet isn't really a matter, but I need the gravity on it to be the same as on earth: 9.807 m/s² * We must have the same kind of [biomes](https://en.wikipedia.org/wiki/Biome "biomes") as on our earth, all with a "slow rain" * No particular expectation on how the water acts when on the ground in a big body of water (sea) * No expectation about frozen water nor snow I've put these boundaries up, because the only way I already thought of was to lower the gravity on Earth, but I'm not sure it would have actually worked. On the Earth we may have a **difference** between someone tall and someone that is small (difference of height about one meter), but it is about 1/10 seconds ([speed of rain drop](https://hypertextbook.com/facts/2007/EvanKaplan.shtml "speed of rain drop")). And I would like it to become **many seconds or even minutes**. [Answer] ## Increase creature's perception of time Instead of trying to twist the planet into doing something impossible, how about modifying the creature? Creatures have an innate perception of time passing. If your creatures have an enhanced resolution or perception of time, then for them rain falling could feel much slower than it does for a human. What if their eyes could see at 600 fps and their brain process it much like how slow motion looks to us? Our normal rain would appear as slow rain to them. The gotcha is that everything would appear to be moving slow not only rain. One second will always be one second, but take a computer for example. To it what it can do in one second is totally different than what a human can do with the same one second. Your creature physically might not be able to move any faster than us, but from our perspective their reaction time and reflexes would seem far superior. If you want more information on how human's perceive time there is a [Wikipedia article on it](https://en.wikipedia.org/wiki/Time_perception). [Answer] What you need is much, much lower [terminal velocity](https://en.wikipedia.org/wiki/Terminal_velocity) for raindrops. > > Using mathematical terms, terminal velocity—without considering > buoyancy effects — is given by$$ > V\_\text{t}= \sqrt{\frac{2mg}{\rho A C\_\text{d} }} > $$ > > > where > > > * $V\_\text{t}$ represents terminal velocity, > * $m$ is the mass of the falling object, > * $g$ is the Earth's gravity, > * $C\_\text{d}$ is the drag coefficient, > * $\rho$ is the density of the fluid through which the object is falling, and > * $A$ is the projected area of the object. > > > You want as low $V\_\text{t}$ as possible. Considering you want it to still be a rain as we know it, $m$ and $A$ are there to stay. You also locked $g$. What's left is $C\_\text{d}$ and $\rho$ — For a slower rain, you need to make your atmosphere denser or increase drag. You can't really change raindrop shape too much, so to increase drag you would have to increase what happens at the water - atmosphere border. 4 times denser or 4 times higher drag will make rain fall 2 times slower. 9 times more dense = 3 times slower, and so on. Note that it would caused severe problems with breathing far earlier than slow-down would reach the level you want. If you want minutes, you are starting to be in the values found in liquids, not gases. --- You could make raindrops smaller. $m$ will decrease faster than $A$ due to square cube law. But it would not look like rain anymore. It would be a [wall cloud](https://en.wikipedia.org/wiki/Wall_cloud) that goes all the way down to the surface. Good thing is - this actually happens in real life sometimes. But I don't believe this is what you really need. [Answer] I've come up with two ideas, not very much steeped in reality, but close enough. * Similarily to Molot's answer, a different sort of atmosphere: You could say that there is a chemical composing enough of the atmosphere, different from anything in our own, which slows the falling of raindrops. Name it whatever you like, Calaomium, Densium, whatever, or pick a dense gas on the periodic table. * The ground of the planet could be a high enough temperature that water evaporates before reaching shorter people. It could be a matter of the humidity being raised enough over the course of a storm that people shorter than the tallest finally feel droplets. Additionally, let's consider... > > On the Earth we may have a difference between someone tall and someone that is small (difference of height about one meter), but it is about 1/10 seconds (speed of rain drop). And I would like it to become many seconds or even minutes. > > > In relation to my first example, there are some interesting implications. Because you want people to feel rain between many seconds to minutes apart, meteorology could be radically different here. According to [National Geographic](https://www.nationalgeographic.com/science/earth/earths-atmosphere/clouds/), clouds can be between 2,000 meters and 15,000 meters in the sky. I really want to avoid using actual math or science here, but if you're looking at the, maybe, 0.5 to 0.25 meter difference being many seconds to minutes, clouds could have rained days or weeks prior to even the first droplet hitting the ground. This interaction makes me really fond of my first example. [Answer] This answer also is about terminal velocity, but just in the oposit way: ## Accelerate the medium in which the drop is falling Do you know these machines? [![enter image description here](https://i.stack.imgur.com/05uhs.jpg)](https://i.stack.imgur.com/05uhs.jpg) Well, I was thinking of something similar. The link you provide states that the terminal velocity of a rain drop is about 9m/s, so if you have a wind going upward at about 8.99 m/s, the drop would take 100 seconds to go down 1 meter. ## Feasability ### Speed of wind The speed of the wind is not too strong for people to stay on the ground. 9 m/s is about a force 5 beaufort, which is descibed as : > > Small trees in leaf begin to sway; crested wavelets form on inland waters. Source: [wikipedia](https://en.wikipedia.org/wiki/Beaufort_scale). > > > ### Wind going upward Well, this is probably the difficult part. You need to admit for the phenomena to be localized, i.e. not the whole world will be like that, only a region. Let's admit there are two regions separated by a very high mountain range. Below the mountains are a network of caves, but instead of having one big entry/exit hole, they have trillions of very very small ones. Your people are living just on top of them. When the atmospheric pressure is different between the two regions, wind is forced through the caves. It will appear to come out of the ground (or be sucked in on the other side). There are [some rocks that are porous](https://en.wikipedia.org/wiki/Pumice), so it's not impossible to build a city on top of something that let the air go through. I am very good at drawing, so I decided to impress you and did an illustration of my idea: [![enter image description here](https://i.stack.imgur.com/31iDv.png)](https://i.stack.imgur.com/31iDv.png) I think this solution is interesting, because it uses the same setting as the earth, no gravity change, no alien breathing heavy gases... [Answer] Of course, ✳here✳ on Earth, heavy rain and light rain is merely a quantitative difference in the amount of water falling. Heavy rain is more water, light rain is less water, but people of varying heights caught in either shower feel it roughly at the same time.   But there are some out of the way places in the polyverse where people in certain worlds experience *heavy rain* and *light rain* quite differently than we do. For example, on Yeola, apart from there being quantitative distinctions of less and more, more interesting still are the the qualitative distinctions between *light*, *moderate*, and *heavy*.   * ✳There✳, when folks speak of *light rain*, they mean that the drops of water are not very dense. They're soft, with perhaps a more open architecture, maybe airier would be an apt description. In any event, such rain drops are more prone to hanging about in the air. Like mist, but more substantial. When these kinds of rain drops fall from the clouds, they float down more gently, glide about, enjoying the ride in the breeze and may even rise up again before easily settling down into puddles. At best, *light rain* is a gentle caress those folks standing at about eight foot or so tall feel upon their faces and shoulders as much as fifteen seconds before the lesser folks, who stand around four foot tall do.   * On the other hand, by *heavy rain*, they mean that the quality of the drops is different, more dense, harder if you will. It's as if more water and denser water were packed into a rain drop. When these little bastards jump from the clouds, they mean business! No floating about in the upper airs for these rain drops! No, *heavy rain* seeks to meet or exceed terminal velocity and from the start, they make a speedy bee-line straight for the earth far below, and they don't care who gets in the way! Unlike their lighter cousins, who often don't even really cause one to become wet, *heavy rain* drops love to aim themselves right at you. Whether vertically, from directly above in big splashsome plops or horizontally, and especially directly into your face, they seem almost to be guided by a malicious will. *Heavy rain*, in fact, is so mean and nasty that it literally pelts everyone, regardless of height. Often painfully and nearly simultaneously. Best you can do, whether you're eight foot tall or four only, when a *heavy rain* begins to fall is crouch under a sturdy tree and hunker down until the storm gives up!   * *Light* and *Heavy rains* don't always travel together. They don't get along well, for even the *light rain* doesn't much like the company of *heavy rain*. *Heavy rain* drops don't pause to say *begging your pardon, but might I pass by?* No ma'am! They just barrel through the airs above without care or concern who they bump into. And when a shower of *heavy rain* passes through the territory of a shower of *light rain*, high up in the sky, it often happens that the *heavy rain* drops will capture and incorporate *light rain* drops in their zeal to pelt the very earth and all living creatures walking or growing upon it. Now, you might think that this is the end of the *light rain* drops so devoured, but not so! In fact, what ends up happening is that, in spite of themselves, the *heavy rain* drops' nature is itself transmuted, softened slightly. In these cases, a new hybrid form, *moderate rain* drops, are formed. More variable in temperament and more labile in nature & behaviour than either parent, a *moderate rain* drop may fall speedily, but not recklessly and generally without malice; or yet it may fall gently, but without dalliance. *Moderate rain* on Yeola, in fact, is much like ordinary rain ✳here✳ on Earth. The tall eight footer might feel a *moderate rain* only half to perhaps three-half seconds in advance of his four foot tall companion. ]
[Question] [ This is similar to [this question](https://worldbuilding.stackexchange.com/questions/10017/how-would-society-react-if-the-existence-of-a-god-was-scientifically-proven) Some scientists found indisputable evidence that the universe is all just a simulation. Maybe they found the code that is running the simulation (I don't know how) and then they demonstrated its genuineness by editing it and changing something, like making a chair a disappear. They don't use it for bad or good after this. Anyway, I was wondering how society would react to this? How would the government keep control? [Answer] **TL;DR:** No one curr, because humans have a lot of emotional inertia, and unless the original discoverers started using it to make sweeping changes, they'd have no incentive to care. (But see the teal deer below for some longer discussion.) --- Like the question you linked, I think the ultimate answer might come down to "Not a lot of people would care, or change their behavior." The thing is, unless you could prove to everyone, everywhere, instantaneously that what you'd discovered was the unalterable Truth behind all existence (perhaps pull up the man pages for the universe on the Moon?), a very large number of people wouldn't even *hear* about the discovery. Consider first that even in a fully industrialized, first-world nation, "important news" about science and technology (which this would be, at first) doesn't disseminate very fast *or* accurately to the populace at large. Most people aren't interested, and most news reporters can't make a science story interesting without needlessly sensationalizing (and thus distorting) it. Granted, finding out the universe is a giant computer simulation would be a very "sexy" story to start with, but you'd absolutely have absurd misreporting on it right from the word "go", and you'd have people who'd just ignore that reporting because it's science and technology and they're more interested in what the Kardashians are doing, or the Super Bowl, or whatever. Second, only a fraction of the human population actually lives in industrialized, first-world nations. Unless and until scientific knowledge of the universal source code is used to eliminate subsistence-level living and give everyone an SUV and a McMansion (or whatever else is deemed appropriate), most people have no incentive or means to notice what's happened in favor of continuing to eke out their lives. [I think, whether or not the scientists who made the discovery immediately started using it for crazy stuff, governments would react immediately and profoundly negatively to suppress what was going on. It undermines their legitimacy *completely* if someone can just rewrite them out of reality. Unless it was a government project in the first place--in which case they would definitely suppress the information, but there might never be any reporting on it to begin with until something like Wikileaks came along! You may want to look at how information on various black ops and other clandestine government programs has gradually gotten released to the public, with the caveat that this is something unlikely to be declassified, ever.] But suppose you managed to tell everyone all at once, before the governments of the world could stop you. Then what? Some possible options I can see are: 1. Deleteman's option of mass suicide. I don't think this particularly plausible on a *wide* scale (i.e. half the human race ups and offs itself) simply because most people wouldn't actually internalize "I'm a simulation, my life doesn't matter". A simple consequence of human solipsism is that, barring physiological and biochemical defects or a lot of emotional trauma, *your* life always matters to *you*, no matter how bad or strange it is. We're just wired that way, and philosophizing out of it to the point of killing ourselves is hard. Suicide is usually an emotional decision. But, for small groups of people and individuals, this undoubtedly would happen. 2. Large-scale rioting, set off by charismatic individuals. I can see two subtypes of this, but there's probably lots more: Subtype one is "THE GOVERNMENT HAS TO PROTECT US" from the possible malfeasance of the terrorists/the amoral scientists/pick-your-enemy using this new discovery to hurt people. Subtype two is "THE GOVERNMENT HAS TO USE THIS TO MAKE OUR LIVES PERFECT". Since you can now end world hunger with a few lines of code, why aren't you *doing* it? Right now? 3. No one cares, because they assume it's all just a fantastic trick. This is the one of the more likely scenarios in my mind, because humans have incredible inertia when it comes to being budged out of their comfort zones. Like 2, this could come in a couple of flavors: "Science is just messing with us, it's not true" versus "If it is true, what does it matter if no one does anything with it?". As a closing note, before my obligatory opinion-and-follow-up-storybuilding questions, I want to say an idea like this (concerning the unreality of the physical universe as we experience it) has already been proposed and is in the process of being tested: It's called the [holographic principle](http://en.wikipedia.org/wiki/Holographic_principle). You could perhaps extrapolate from how little most laypeople know about or understand that to how they'd respond to the universe as a simulation. **Warning! This next bit is opinion!** I think the more interesting scenario that you didn't touch on--and one that's much more likely in my mind--is what happens if the original discoverers keep it to themselves and start using it to rewrite reality to their benefit? Given the power to become a god, I can't see even the most dispassionate, dedicated scientist just passing that up. So much the better if their initial understanding of the universal simulation isn't very good, and they start writing buggy code for it... Honestly, I think the better story to be told here--or the *first* in a series of many stories to be told here--would be how the discoverers handle knowledge of their discovery. Is it ethical to start tampering with the simulation, knowing they could glitch everyone out of existence? Should they tell anyone? And so on. Much of how the world reacts depends on what these people do; I know your original specification was that they just demonstrate it's all a simulation and then immediately vanish from the world stage, but is that the most *interesting* possible way to handle things? [Answer] The big question is, "Who is in charge of the simulation?" In the same way that technology sufficiently advanced is indistinguishable from magic, a simulation sufficiently cohesive is indistinguishable from religion. The question could just as well been phrased as, "Scientists announce that they have proven God's existence and can demonstrate how he works." Thus, I disagree with Deleteman's initial statement. I don't think there would be mass suicides. Somewhere between 87 and 92% of the world's population already [believe in a God](http://en.wikipedia.org/wiki/Demographics_of_atheism), and I think that they would suddenly and fervently express that they know exactly who is running the simulation, and what that being wants from its creations. I think there would be a re-sparking of ancient wars, and I think tons of resources (billions of dollars) would go into communicating with our maker. I think a lot of people who had simply never thought much about it would start to wonder, "What is it all about?" and perhaps re-think some of the existing religions that they'd always discounted. Atheism would just become another religion, really. Those who will fervently say, "This doesn't make them worship-worthy, they are just beings with complete power over our world and lives." But there would be a large culture that just doesn't care about that. They just discovered that the world itself is hack-able. I, myself, would be looking for the cheat codes. Seriously, someone just demonstrated that I could have the power of flight and indestructibility with just a few lines of code? Hellz yeah. [Answer] **How individuals would react - "Cogito Ergo Sum"** [René Descartes'](http://en.wikipedia.org/wiki/Ren%C3%A9_Descartes) most famous saying is very relevant to this situation. In English, it is "I think, therefore I am". > > In his Discourse on the Method, he attempts to arrive at a fundamental set of principles that one can know as true without any doubt. To achieve this, he employs a method called hyperbolical/metaphysical doubt, also sometimes referred to as methodological skepticism: he rejects any ideas that can be doubted, and then reestablishes them in order to acquire a firm foundation for genuine knowledge. Initially, Descartes arrives at only a single principle: thought exists. Thought cannot be separated from me, therefore, I exist... Therefore, Descartes concluded, if he doubted, then something or someone must be doing the doubting, therefore the very fact that he doubted proved his existence > > > If we found out that the world was some virtual reality simulation, each individual could apply Descartes' logic to prove that they exist independent of the simulation. If you think and are capable of doubting, something or someone must be doing that doubting. Therefore you exist. Note that this is a very personal proof. If we knew the world was a virtual reality simulation, I can prove to myself that I exist, but how do I know that you exist? How can I tell that you're not just a program that is complex beyond my ability to comprehend and can therefore perfectly simulate what another person would be like? If you think of it like [The Matrix](http://en.wikipedia.org/wiki/The_Matrix), then how can I tell if you're another person trapped in the matrix or if you're an agent? This doesn't actually prove *what* you are though. You can just be certain that you are *something* real. Perhaps you are a computer connected to the internet, and the world is simply the manner in which you perceive that connection. Because individuals can prove to themselves that they are real but can't prove that others are real, how will society change? The answer is that it probably won't change. There will probably be some shifting around of specifics - some people will get depressed that their lives are being controlled by some unseen hand, while others will find hope in that there is something more. People who are unhinged anyway might choose it as their reason to be destructive ("You're not real! You're all just agents trying to keep me down!"), but they probably would have gone and done something stupid anyway. Big changes to society would only happen if either the simulation admin steps in or we learn how to reliably manipulate the simulation. If the admin steps in, then anything could happen depending on what he/she/it does. It could be that the admin would simply patch the simulation and make it impossible for us to recreate the "indisputable proof". We'd stop believing the proof because we'd have no way to know if the nature of reality had been changed or if it was just some crazy coincidence that created the "proof". Think [cold fusion](http://en.wikipedia.org/wiki/Cold_fusion). If we learn how to reliably manipulate the simulation, it's just another technological advancement. If all we could do was move people from one location to another, then it's the same as if someone had invented a Star Trek transporter. You can look to [the Renaissance](http://en.wikipedia.org/wiki/The_Renaissance), [the industrial revolution](http://en.wikipedia.org/wiki/Industrial_Revolution), and what's happening now because of computers as examples of how technological advancements can change society. [Answer] Well, you don't specify much, depending on the type of evidence, many things could happen. But one is certain: **massive suicide**, I think that *upon hearing the news* the shock would be so hard on some people, that a lot of them would kill themselves, just because "we're not alive anyway" or some other reason like it. Afterwards, when the "smoke" settles and they start to realize that it is all very subjective, it could turn the other way around. If we actually found proof that we can alter our reality, I would imagine a new branch of science would open up, studying our new found reality, understanding it and trying to conquer it. Once we gain enough understanding of our reality, where we can shape it into anything we want, I would imagine our digital selves would have a great live, but the search for our creators would still continue. Now, depending on whether the creators of this reality are actually monitoring it or not, we could be getting into trouble after we start messing with it. One of 4 things could happen here: * They see us, they take our awareness as part of our evolution and continue silently monitoring us. * They take action and fix the "bug" that allowed us to tap into their code. * They shut down the experiment (meaning, our simulation, we stop existing). * They see we've surpassed their expectations and communicate with us Either scenario can lead to very interesting stories. [Answer] According to Bostrom, there's a high probability that we are living in one, yet it had no society wide impact. When I encountered the study, I must admit that I had a strong doubt to begin with, and personally it didn't change my belief or the way I live. * Bostrom, N. , 2003, Are You Living in a Computer Simulation?, Philosophical Quarterly (2003), Vol. 53, No. 211, pp. 243-255. [Answer] This started off as a somewhat light hearted, tongue in cheek and pedantic comment - but it rapidly became apparent that it's the obviously correct answer. [Flame shields up :-)]. > > [if] ... scientists found indisputable evidence that the universe is all just a simulation... I was wondering how society would react to this? > > > Glossary: Using "programming" as metaphor for system performance design. The answer is completely obvious - They would react in whatever way they had been programmed to react. If the discovery had not been specifically "hard-coded" for they would react within the constraints on behaviour established by the program. Assume (if assumption is felt necessary for something so obvious :-) ) that we currently exist as part of such a "reality": As we are not currently privy to the program's constraints the answer is necessarily unknowable in full detail. What we can know of the answer is also constrained by the program and the programming and the constraints based on it. The capabilities required to implement such a system are of such magnitude that it seems unlikely that all such avenues would not have been thoroughly tied down. Unless it was perhaps part of the equivalent of a standard 3rd year college project assignment. Long ago (... looks ... )February 1994 I see, I wrote a short story that was based on exactly that premise. The outcome was predictable. Alas it necessarily contained far more techo speak than any audience I had available would tolerate. Maybe things have changed in 20 years :-). > > How would the government keep control? > > > As above :-). [Answer] Most people wouldn't believe it. (or to quote @memming (who has answered since I posted this): "personally it didn't change my belief or the way I live.") The science (or logic) is too hard for most people to grasp. They can't even acknowledge *measurements* of phenomena. Thus, FOX news is still a thing. OTOH, it would definitely resolve the Creator issue - which is why I don't think we're going to be able to prove it to anyone's satisfaction. [Answer] Well, I guess the reaction would be similar to that of proof of humans being a significant source of Global Warming and Climate Change, and Western governments beating the pants, skirts, shoes and socks off the former Stasi. Inertia and apathy would win the day, aided by strong financial interests of the established powers. Perhaps that's the *real* reason behind mass attention deficit syndrome and apathy? Making the simulation robust against self-discovery? [Answer] I don't know whether there can be "indisputable proof" of a virtual reality. We have the right to dispute anything. Materialists of course dispute any challenge to materialism. The fact we are creating technology and making life and the world the way we want it, certainly virtualizes reality, don't you think? I'm not a believer in reality, feeling such reduces to authority assertions only, of what should be and what is. Why isn't reality already virtual? When Plato asserted what is and what is not, where did he get that from? I see everything as virtual, myself. We make it all up. [Answer] There are already some great answers above, but I think one thing is overlooked: I think some people will want to *communicate* whith the guys taking care of the simulation (at least, that's what I would do...) And if possible, communicating before they shut the simulation down would be better... [Answer] I think that such a discovery, would have a huge impact on society. * Perhaps there would be mass suicides, but not as many as other answers suggest. * There would be some problems with people following "I'm a machine, so I'm not responsible for my actions" reasoning. * The domain of physics would be changed forever, but I'm not sure in what way. * There would be humanity-wide project attempting to **communicate with our creator(s).** * If the creators do not respond, I guess there would be at first a steady decrease in trust between people and depending on how fast each society manages to counter that, it might lead to anything from small recession or some martial law to total collapse of civilization (and possible rebuild unless we wreck the planet in the process). * If the creator(s) respond, then all bets are off, my model of our world doesn't know how to handle such case. I hope this helps $\ddot\smile$ [Answer] People would not react much because: 1) It would have no impact on their daily lives. 2) There is no difference between living in a sufficiently advanced simulation and living in a 'real' universe. 3) The majority of people believe whatever they want and ignore current scientific facts, this would be no different. [Answer] I depends on what people CAN do. If they can't do anything new, they will probably just do what they have always done. If they can use this to their advantage, they will try to do so. It all depends on what exactly happens. I do not see any big changes in society if only we know that it is a simulation. We would try to understand it better, we would try to interact with the simulation (trying to break it/escape it/communicate with the Makers). You might think people will change their Religious Ideas. I think this is unlikely if we gather no new conclusions beside it being a simulation. Atheists will say there is a "god", but there is no reason to act differently. Religions will say duh, this simulation is made by god. Thats what we have been saying all along. In the end, nothing would be different if our Reality was a Simulation right now. To be fair this is all from my point of view. People might be "stupid" and do irrational things. [Answer] ## They wouldn't. We have overwhelming data that climate change is a real thing that is going to have real repercussions. But a significant number of people pretend the data isn't real. They cook up vast conspiracy theories to explain the science, rather than believe the science. (See also: evolution; age of the universe; Big Bang theory. Etc.) When people are faced with a new idea that runs counter to their personal beliefs, their first response is to deny that new idea. Sometimes violently. ]
[Question] [ Let's take our regular "Great Blue Star Whale", with a mass of about 10 000 tons. That poor, poor whale is reaching the end of its life for whatever reasons. (Damn you! Space whale hunters!). It will interestingly crash into a planet. That planet is not too dangerous (no endless volcanoes or corrosive sand) but it is uninhabited. My question regards the possibility for life to evolve and expand from the corpse of the space whale. Would it be possible / realistic for something like this to happen? A few things we'll consider : * The insides of the space whale are protected from outside influences (gravity still applies) * Some of the whale's cells are still alive * The whale is biological and potentially edible * The corpse may stay at a reasonable temperature for a prolonged amount of time May life even grow inside the corpse without ever needing to go out ? [Answer] Crash isn't the word when a star whale hits a planet, the word is splash. > > A spider'll not even notice a drop like this, a mouse'd walk away, a horse'd break every bone in his body and a helephant would splash - *Wee Mad Arthur (Terry Pratchett) - Feet of Clay* > > > You're going to end up with bits of whale spread over quite a bit of the local scenery. Digestive bacteria would still be going strong but the whale as a whole is very very dead. Life could well evolve on the planet as a result of this, how easily is down to the diet of the whale and how well the surviving bacteria can adapt to available food sources on the planet. If there happens to be a type of rock that the whales could break down that's plentiful on this world then you're home free. When it comes to life going outside the whale... after that landing it's most definitely outside. There's not a lot of inside left. [Answer] # Photosynethetic plant-life and bacteria, yes First it needs to be said... > > And wow! What's this thing suddenly coming toward me very fast? Very, very fast. So big and flat and wide it needs a big wide-sounding word like ...o ...ou ...ound ...round ...ro ...ground! That's it: ground! I wonder if it'll be friends with me. > > > But, in all seriousness, the answer to your question is: **Yes, a creature like that can very well kickstart life on an otherwise lifeless planet** The animal cells of the creature itself are unfortunately doomed to die, and rather soon(\*). However, it may be carrying passengers. Any plant life or bacteria that uses photosynthesis for its metabolism may catch on and thrive. The most obvious and interesting among these (if we assume an Earth-like origin for the creature and an Earth-like destination) are probably [Cyanobacteria](https://en.wikipedia.org/wiki/Cyanobacteria). Assuming your poor creature splashes down near free water, then this kind of bacteria is not only likely to thrive, but to have other interresting effects on the planet, such as [oxygenation of the atmosphere](https://en.wikipedia.org/wiki/Great_Oxygenation_Event). As for the bowl of petunias... [![enter image description here](https://i.stack.imgur.com/6RlEK.jpg)](https://i.stack.imgur.com/6RlEK.jpg) *([Image source and credit](http://p-korle.deviantart.com/art/Bowl-of-Petunias-63612868))* ...well same thing really. If it is carrying any plant life that can survive without being dependent on nutrients from pre-existing life, then plant life can — quite literally — take root. It must be noted though that with evolution being the extraordinarilly slow mechanism that it is, [it will take a few **billion years** until there is widely diversified life of the sort that we think of](https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life). (\*) Then again... a **space whale** that can life in the extremely harsh conditions of outer space?! Seems like quite tough animal cells if you asked me. And there are some — indeed — [immortal cell lines](https://en.wikipedia.org/wiki/Immortalised_cell_line) in Earth as well. Maybe, just maybe... [Answer] ## Seems Plausible *IF* It's a Sperm Space Whale: cue "Panspermwhalia" If the average earthly whale is anything like the average space whale, then it seems very likely some of the intestinal contents will still be alive and some can continue to thrive: > > A body’s intestines are filled with micro-organisms in their millions, and these do not die even after the person dies. These micro-organisms start to break down the dead intestine cells. Others like the bacteria known as coliforms and clostridia start invading other body parts. > > > (Source: [How Long Does It Take for a Body to Decompose?](http://www.enkivillage.com/how-long-does-it-take-for-a-body-to-decompose.html)) In that environment, evolution could easily continue via mutation, natural selection, etc. Obviously, though, the chances of inseminating new life on a planet are higher if a thoroughly potent source is involved. Hence, Sperm Space Whales are most likely better candidates for whale induced panspermia (but I do not speak from experience.) [Answer] As far as life springing forth from the corpse of the whale, I'm not quite certain that could happen. However, the whale could be the catalyst to awaken bacterium that have been dormant for any length of time on the new planet. The whale's corpse would provide the "nutrient solution" that the bacterium need to revive and grow. A variation of this occurred in New Mexico in October, 2000. Here is a short article that might be helpful - <http://news.bbc.co.uk/2/hi/sci/tech/978774.stm> [Answer] Usually questions about space-whales are a steaming pile of pseudoscientific twaddle, however, this question confines itself to something sensible. The OP may congratulate himself. For the sake of scientific sanity, it is assumed that space-whales are otherwise whale-like creatures created by extremely advanced alien technological civilizations. Basically they are cyborg marine mammals equipped with environmental protection systems to enable them to survive in space, and a propulsion system for easy travel around the galaxy. The core question is essentially whether dying or dead whales "beaching" themselves on alien planets can be a source of life dissemination. Basically, panspermia by dead space-whales. So the question is would this work? Could life on a planet be initiated by the cells and tissues from a dead whale? The simple answer is no. Possibly the DNA from those cells might form the precursors to life on the planet, but this should be regarded as extremely improbable. So no. What is more probable to be a source of life on a planet is the microbiota carried by the space-whale's body. If microbes could become established in the planet's environment they could colonize the planet. However, there are caveats about the fact that these micro-organisms will be well adapted to the environment and ecology of the space-whale's body this will make it improbable, but not impossible, for dead space-whales to be the vectors for spreading life to otherwise lifeless planets. Possible, highly improbable. May life even grow inside the corpse without ever needing to go out? Sadly, no, even ten thousand ton dead space-whales don't last forever. Their tissues will either run out or break down to the point where the viable existence for any organisms living inside a dead space-whale will run out. Eventually the outside environment will break in, and the space-whale won't be anymore. So, for a short time, yes, but not in the long run. ]
[Question] [ I am drafting a short story about a small object orbiting the Sun at the precise 'speed' as Earth's opposite the Sun, undiscovered by us due to its position. The problems I see with this include the following. 1. We would have detected it by now, because of the gravity that impacts other objects in the solar system. How small would it have to be (just an order of magnitude is fine) to not be detectable? 2. Would our spacecraft beyond Earth have 'accidentally' snapped a picture of it? 3. Must it reside at [Lagrange Point](http://en.wikipedia.org/wiki/Lagrangian_point) 3 ($L\_3$) in order to have our orbital period? --- Side note: I was re-phrasing the question to go from "small planet" to "dwarf planet" and accidentally deleted the wrong word. Before posting I looked up to see I had written, "What are the possibilities of a dwarf orbiting opposite Earth's orbit?" and truly laughed out loud. That would have gotten some weird looks haha. [Answer] The point directly opposite Earth on the other side of the sun is called the L3 Lagrange point. It's not quite at the same distance from the sun as the Earth is, assuming that the body residing there is smaller than the Earth, since both the gravity of the Earth and the sun pull on it. However, the L3 point is a saddle point in terms of gravitational potential, meaning that it is an unstable equilibrium point. Anything in the L3 point will eventually drift away, given sufficient time. Eventually, it would probably drop into an orbit around either the L4 or the L5 points, which would be visible from Earth. We also probably would have seen the planet by now, given that there were [quite a few people who theorized exactly such a planet,](http://en.wikipedia.org/wiki/Counter-Earth) starting with Aristotle and continuing into [some works](http://en.wikipedia.org/wiki/Gor) of modern science fiction. [Answer] Under 100km, and probably not even then. <http://en.wikipedia.org/wiki/Counter-Earth#Scientific_analysis> Probes sent to Venus and Mars wouldn't have arrived if there was anything bigger there, as they used gravitational slingshot effects. Venus would pull it out of orbit. Smaller bodies would be more affected by Venus's pull. STEREO probe launched in 2006 would've detected it. It's in the Sun's orbit, not Earth's. If there are EM emissions, the Sun's wobbling motion (rotation) around its barycenter would reveal them for part of the year. Earth doesn't orbit in a circle, but an ellipse - and thus is moving faster during parts of its orbit, and thus can see things during parts of the year that it couldn't see during other parts of the year. You need to make your counter-Earth recent or specially hidden (high-tech). Also, what's the story purpose? If you want something hidden, there are other places to hide it. If you want something that's easy to get to, that's not particularly easy to get to. [Answer] As others have stated, the L3 point is unstable. As well as the already mentioned L4/L5 that are well observed. An interesting alternative orbit might be a [Horseshoe Orbit](http://en.wikipedia.org/wiki/Horseshoe_orbit). Combined with really-good-radiation-absorption, and with sufficient smallness, such a body would be tricky to spot. [Youtube vid of Horseshoe Orbit](https://www.youtube.com/watch?v=h8Ge8n6Qaf8) An in-universe explanation for the lack of detection could be a covering of near-perfect solar panels (ie absorbs all light/radar for internal power) It would have to be spotted by a transit in front of other stars/bodies, and this difficulty would be compounded by the changing relative positions between the body and the Earth. Edit: Added link to video [Answer] Well the first problem is that if there was Earth 'technically' isn't a planet! ;) Hasn't cleared it path... But I don't think we would have gotten a picture of it until the 70's or 80's but there is a reasonable chance that it would have been caught on film somewhere. Also the planetoid/dwarf planet,asteroid would have to have the exact same path as the earth or the two would have collided long ago. I tried looking up info on orbital decay, but didn't find what I was looking for. I do suspect that the Earth and a smaller body, even if starting on the exact same orbit would decay at different rates and thus eventually collide. You could always use any other dwarf planet/large asteroid we have identified so far (or a new one!) to host alien artifacts. Next best would be some kind of stabilizing tech on the dwarf planet to keep it in place exactly opposite the earth. Just have someone 'discover' it in the old photos from one of the missions. Any one of the mars missions might have spotted it, since mars takes twice as long as earth to go around the sun. [Answer] If your goal is to have a body near Earth which is in a stable orbit for aliens to have stashed stuff, go for an [Earth Trojan](https://en.wikipedia.org/wiki/Earth_trojan). The L4 and L5 points are stable, meaning the aliens can rely on the rock being there for a while. Trojans potentially take less delta-V to reach than the Moon making an immediate manned or robotic recovery mission plausible. The first, and only, Earth Trojan yet discovered was [2010 TK7](https://en.wikipedia.org/wiki/2010_TK7) in 2010. It's small, 300 meters, so it has no gravitational impact. It has the [albedo](https://en.wikipedia.org/wiki/Albedo) of asphalt or a forest, so it's hard to see. You don't have to be on the opposite side of the Sun to have not been spotted yet, it's totally plausible there's more and we just haven't seen them. A scenario could be this. A new space telescope is launched, or an old one is repurposed to look for Earth Trojans. Your target is spotted. NASA decides this would be a great candidate for their [Asteroid Redirect Mission](http://www.nasa.gov/content/what-is-nasa-s-asteroid-redirect-mission). A probe is sent to pluck a "boulder" off the surface and it turns out to be not a boulder. A manned mission is sent. [Answer] As others have said, the L3 point is unstable, and any mass of significant size would have been detected already through perturbations of Venus's and Mercury's orbits. However, space is vast, and small things are *really* small in space. A more likely location for a hidden object like this would be in either the asteroid belt, or as a [Jupiter Trojan](http://en.wikipedia.org/wiki/Jupiter_Trojan) (in the L4 or L5 points). The object would also need a *very* low [albedo](http://en.wikipedia.org/wiki/Albedo) (reflectivity) to escape detection. If you wanted to push it, you could conceivably make your object an Earth Trojan (only [one](http://en.wikipedia.org/wiki/2010_TK7) Earth Trojan has yet been discovered). [Deimos](http://en.wikipedia.org/wiki/Deimos_%28moon%29) would be a good reference. It is only 24 nanoEarths in mass, with an escape velocity just a little faster than you can jump. If it had a very, very low albedo, something that small could conceivably have gone undetected (but we could have taken a picture of it). In fact, the only way we'd find something like that is if we watched it occult one or more stars/planets. However, since we know this is a stable point, we would be looking for things here. [Answer] I'd like to point out that the L3 spot, although not parked, is passed through by some solar observatories that co-orbit with the Earth like [STEREO](https://www.wikipedia.org/wiki/STEREO). While passing through, they searched L4 and L5 for small bodies. Their current position is rather interesting; [here is a chart](http://stereo.gsfc.nasa.gov/where.shtml) and a static snapshot, rather close to crossing at the point you are interested in.: ![snap](https://i.stack.imgur.com/CXWAQ.gif) So, **here is an idea** to use in your story: this is how the hard-to-see object is discovered by humans. The spot is like parking at the top of a hill wit no parking brake; you don't expect anything to stay there. So it is a surprise to find something that looks like a tamed comet! It is covered with a regolith to keep the ices shielded in side and has an odd shape that causes it to tumble rather than rotate on a normal axis. It sometimes allows puffs of gas to escape in just the right direction to keep it parked. In fact, the jet as tenuous as it is was how it was spotted. The two crafts send a radio signal and mutual optical inspections as they passed. The jet let them back to the object. [Answer] 1 Maybe. It depends on how small it is. Small bodies do not cause so big perturbations on bigger bodies. Something like Earth itself would be detectable by perturbations on Mars and Venus, but Ceres most probably not. Anyway, such a planet is most probably nonexistent since it would interfere with [Cruithne](https://en.wikipedia.org/wiki/3753_Cruithne), and it does not. 2 No. It is exactly at the other side of the Sun. It is impossible to detect it from any spacecraft near Earth-Moon. It may have been photographed by missions to other planets, like the Voyager ones, but their cameras hardly point towards Sun. 3 No. Lagrange points are for smaller bodies, and L3 is not a stable point. The location would be at the same distance from the Sun than the Earth is (1AU), since orbit is independent from mass. [Answer] I believe that others are mistaken about the L3 point. Rather than the L3 point being on the other side of the Sun from the earth, it is on the other side of the Earth from the sun. This is why the point is an unstable "orbit" - because it is not going around the sun in an ellipse, but rather in an orbit that is one of 5 solutions to the 3 body problem. The actual point on the other side of the sun from the earth would have a true elliptical orbit and *would* be stable, although probably not for billions of years just because it would have a slightly different rate of orbit decay than the earth due to its differing surface area/mass ratio. Edit. After the comment below was posted I did some research and it turns out my memory was wrong. The L3 point is indeed an elliptical orbit, but around the Earth-Sun balance point rather than around the sun's center of mass. The reason it is unstable is not because it lacks the stability of an elliptical orbit, but rather because the stability requirements of this particular elliptical are much more stringent than stability requirements of other planetary orbits, in that if the other planets of a solar system pull a planet out of its ellipse, it just goes into another, very similar ellipse. In this case, they would interfere with the relationship between the hidden planet and Earth, which would provide consistent gravitational bias. Sorry about the confusion. ]
[Question] [ The people in my story's universe all have various magical powers, and if they want the effects of these powers to extend to their clothes or equipment, said equipment needs to be designed to a few specifications in order to comply with my world's method of "syncing" objects to their owners' aura, an invisible field that extends 3 inches out from every part of their body: 1. The object must at least be small enough that it can be encased completely inside its owner's aura for five minutes, to "sync" it. You can't sync anything too big to fit inside the aura when pressed against the human body. But once initially synced, this never has to be done again unless the object is significantly damaged or warped (or if the object is synced to a new person). 2. When you want to use it with your magic, the owner's aura must be touching at least part of the object to affect it. 3. For the purposes of the above two requirements, an "object" is defined as a solid collection of bonded atoms. A screw, for example, would be treated as one object, but if you're syncing a mousetrap, then the wooden board would be one object, the spring would be another, the metal loops attaching the spring to the board would be the third and fourth, etc. The major takeaway from this is that if you want to be able to use certain types of magic properly, your weapon needs to be designed with as few pieces as possible, or, bare minimum, have all of the pieces be constantly within 3 inches of some part of your body while in use. Now, this is pretty easy when it comes to swords, and not even out of line with how swords are already made. The blade, pommel, grip and guard all have at least some part of them that is within 3 inches of the user's hand at all times when in use. But when it comes to things like lances or halberds, there are going to need to be some major changes to their designs. Real-life polearms were typically made with wooden hafts that then had the metal blade/point attached to the tip of them. This obviously means that the blade component of a normal polearm is too far away from the user's hand (or any other part of their body) for their aura to reach it. Ideally (at least for the purposes of use with magic and nothing else) a polearm, both the haft and the blade, would be made out of one uninterrupted piece of shaped metal. But 1, this would limit the length of the polearm to roughly the user's height (see rule 1), and 2, my understanding is that polearms were designed the way they were because wood is both lighter and cheaper than metal, making a wooden-hafted polearm significantly more cost and energy efficient than one that was a single, long, solid piece of forged metal. But we're talking about being able to carry it with you when you do things like teleporting and walking through walls, so obviously some sacrifices to the ideal design would be worthwhile to take advantage of this. The only question is what those sacrifices would look like. ***What is the best way to design a polearm for magic compatibility while making the fewest compromises to the advantages of the ideal real-life design?*** [Answer] **Langets** Real polearms often had langets, or strips of metal attached to the head that extended a significant length of the pole. This made it hard to simply snap the pole off and made the whole thing much sturdier. The small amount of added weight was well worth the better strength. If your mages are going to invest in a polearm they will have langets, not just a socketed shaft. If they need a metal connection to work smiths will make such pole arms with tapered langets that extend the length to the weapon. They can be thinner and lighter than normal langets especially past a certain point since they are less to add strength and more to supply a connection. The lower part of the langet could even just be wire. You can even go further and weld the rivets on one side, so there are only two pieces to the entire thing: one metal and one wood. This will weigh the same as a normal usable polearm. Fitting will be a little bit of a pain but well within a decent weaponsmith's capabilities. As a bonus this works for any hafted weapon, so they can do it to axes and hammers too. [![Pike with a riveted langet](https://i.stack.imgur.com/r83rql.jpg)](https://i.stack.imgur.com/r83rq.jpg) [![War hammer with langets](https://i.stack.imgur.com/Swn22l.jpg)](https://i.stack.imgur.com/Swn22.jpg) ([source](https://www.deviantart.com/sgainbrachta/art/War-hammer-langets-293844421)) [Answer] * Break down the polearm in shorter cylinders. Think of bamboo cane sections. * To assemble the polearm, attach each cylinder to its neighbor with a suitable joint. * Run a wire from one end to the other, and tension it to ensure proper stability to the assembly. With the above design you can have a polearm which is longer than the bearer height, and yet to charge it, just wrap the unmounted cylinders, joints and wire around the body. During charging they will count as multiple, individual objects. During usage there will by physical continuity among the components. Moreover, for added security, one end of the wire can be make touching the handle, again in contact with the aura. When it is mounted, part of it will be in touch with the bearer hand, thus within the aura. [Answer] Multipart lances are a thing. ![Collapsible lance](https://i.stack.imgur.com/NUl89.jpg) ![Collapsible lance](https://i.stack.imgur.com/QUcWr.jpg) I think the images should be self-descriptive. Imprint on the parts, then assemble the whole. You can switch the tip for some blade of your liking. Or make your aura bigger and enchant a single part pole weapon. Some mystical traditions on real Earth have aura enlargement training. [Answer] This might be a little out of the box, so let me know if it breaks any other concepts. What about syncing materials and then crafting with them? I think that could actually be pretty cool if you're talking about syncing being a more personal experience. Although some items are small enough to sync post-creation, there may be others that must have their materials synced due to being too large. You said that an aura extends 3 inches out, but I'm also going to assume that the whole item needs to be enveloped in order to sync properly. Or else, it would be just a matter of holding the item for long enough in the first place. If you can sync materials before crafting them, you can make larger synced assemblies. Of course, that might take a lot more work, but adds a bit to the charm of the personalized aura sync, I think. [Answer] It depends on the purpose of the polearm. Longer polearms are actually harder to use in one-on-one combat. Pretty much outside of 1.5 your body length and you might have difficulties with it outside of horseback or a unit formation. For the purpose of magic, I think the condition would void most of the polearms, axes, hammers, bow and some of the wooden weapons like wooden staff with metal tips. There are no realistic way to do it because even a full length polearm made with a thin tube of metal with wood underneath would require some form of riveting or screws to keep the heavy duty tip on the stick. ]
[Question] [ In pop culture Vampire teeth are often assumed/shown to be just like human teeth except that they have fangs instead of canines. After spending way too much time in front of the mirror, making weird faces, I have come to the conclusion that the canines are too far back in the mouth to be properly placed for biting. However, due to the amount of orthodontia work I've been through, the amount I still have to go through, and the fact that I've never bitten anyone to drink their blood, I have no idea if this is correct. **Tell me if I'm wrong or not** * If I'm wrong, explain why the canines are ideally placed for biting * If I'm right, explain where in the human mouth the fangs should be placed, with explanation * Or redesign a human looking mouth/set of teeth with fangs that with exception of the fangs looks human at a glance to a non-dentist or non-vampire hunter **Criteria** * Exactly two fangs * Resulting puncture wounds should be about (but not absolutely required) an inch apart to match most pop culture depictions * Must be ideally placed to puncture blood vessels in human neck (preferably the jugular) * Can be *any* two teeth, in the top and or bottom row, but both in the top row preferred, and horizontal symmetry preferred * Blood (human) is the only food the vampire(s) needs to eat, fangs can interfere with or completely prevent consumption of any other food or liquid **Probably important things that I'd rather you ignore for sake of questions I'm planing on turning this into a series with** * Length * Retract-ability * Do they actually suck the blood via the teeth, or just puncture the skin **Related** [Convenient teeth for a bloodsucking vampire](https://worldbuilding.stackexchange.com/questions/114176/convenient-teeth-for-a-bloodsucking-vampire) Especially the first answer **Recap** Where should Vampire fangs be located in a (probably) human mouth? [Answer] Try biting yourself with just enough force to leave a mark. It'll probably look like this: ![Human bite mark](https://i.stack.imgur.com/GlspI.jpg) You can see the canines' marks, but not the molars. Molars won't reach, they're out of the question. So the decision must be made between incisors and canines. If you pierce the skin with incisors, more blood will fall out of your mouth than if you pierced with the canines. Canines are the teeth farthest back to hit, so piercing with them keeps more blood in the mouth. So I think the classical notion of canines is best, but with a twist: by making the lower canines the vampiric teeth rather than the upper ones, you can collect even more blood successfully. [Answer] Actual vampire bats have their teeth (the inner pair of upper incisors) modified, not as puncturing fangs, but as slashing blades. They feed by slicing away a strip of skin and lapping the blood that flows out, with an anticoagulant property of their saliva preventing premature clotting. This type and location of fangs seems most convenient for any mammal. With a little modification of facial shape (to allow the teeth to clear the nose), this would work very well for a humanoid vampire. Better by far than puncturing and trying to suck through the resulting wounds. [Answer] All you *really* need is one fang to pierce the cartoid artery. The bodys own blood pressure will literally pump the blood right into your vampiric mouth. The problem with fangs in the upper jaw is that a puncture from a bite would pierce the skin at an angle. This poses the risk of you not being able to capture all the blood, leaving behind a mess and making you extremely suspicious. Since the lower jaw is much more flexible, the chances of making a neat, staight hole is much higher. The tongue - that can aid you in finding the right angle to bite - is also positioned in the lower jaw and at a perfect position to feel your lower fangs and whatever they're biting into. As for the best angle of the fangs in a vampire's mouth, it seems that slightly pointing forward (out of the mouth) would yield the best results. * Inward pointing fangs are perfect for *holding* slippery prey (think of shark's teeth), but they pierce the skin at an angle that is not best for catching the blood flowing out. * Straight teeth are common in predators that need to hold onto their prey but also kill it with a bite to the jugular. They seem to be the most utilitarian solution for a vampire as well. * Outward pointing teeth are plain weapons (think of wild boars) but to be suited for a vampire, the angle cannot be too flat. The vampire could pierce an artery with great precision and have the blood flow *directly* into his mouth. He could control the blood flow by only partially retracting his teeth from the puncture wound. But which teeth should it be? I think any pair of teeth from the central incisors up to the canines would be suitable. The incisors probably more so, because they are at the very front of the mouth and the tongue could guide the teeth to their target with greater precision if they are both within range of the tip of the tongue at the same time. The canines are too far apart for that. **Summary:** The fangs of a vampire should be a pair of incisors in the lower jaw that slightly points forward (out of the mouth). [Answer] # Reframe: why just teeth? Honestly, the whole “vampire teeth” thing never really clicked for me. As noted by @Zeiss Ikon, actual vampiric mammals don’t use teeth to puncture skin, but to tear the skin. Human teeth are relatively fragile, and would be even moreso if elongated enough to overcome natural skin elasticity and drive past the surrounding, lesser teeth. You’re asking to have your main feeding instrument snapped off by struggling prey, and gating your entire ability to feed on the presence of just two teeth. # Use your tongue Cats, large and small, have papillae on their tongues, little spine like things. On a little cat, this makes their tongue feel like sandpaper. On big cats, it’ll take your skin off in two swipes. ![Lion tongue ](https://i.stack.imgur.com/AvA2t.jpg) If you have a tongue like that, it will give you a much wider surface area to get blood from, so you don’t have to depend on hitting an artery. If you *have* to have puncture wounds, then a pair of only-slightly-longer canines in the bottom jaw will help you hang onto squirming prey, without needing long-and-fragile teeth. Punctures will be coincidental to the feeding, and thus, even elderly vampires who have lost teeth will get to feed as usual. Bonus: it’s much easier to go incognito. The spines on the tongue retract, and less pronounced fangs will keep you safe from hunters. [Answer] As has been pointed out, molars won't work - they are too far back. If you think about it, any position forward of the canines won't work either - they will interfere with speech, specifically the interdental fricative. Try making a prolonged "th" sound, and feel where your tongue is extending beyond your front teeth. Your "Must be ideally placed" requirement is difficult to understand, except as it seems to favor forward teeth. While the external jugular is probably the target for the vampire bite marks I've seen (in the movies, of course - what did you think I meant?), the internal jugular and carotid arteries are actually a good deal more convenient, being located just behind the trachea. These vessels are more convenient in the sense that they don't require a vampire to open as wide, although they do require longer fangs. [Answer] They are hollow from the back.. so that with the tongue against the roof of the mouth a sucking action just like a baby at a nipple results in the blood coursing up the hollow channel in the back of the tooth and makes it easily invited. Curved to hold but only slightly, enough to create a lovely vortexing flow of the blood which never has to make a 90% bend.. it keeps the blood cells imagining they are still in their natural motion, no real trauma on a cellular level... Violent feeding only creates violent vampires.. there is no need for cruelty or pain..just pleasure for all.. [Answer] If you've ever opened canned juice, you've probably done it with two holes: [![enter image description here](https://i.stack.imgur.com/KD9Anm.jpg)](https://i.stack.imgur.com/KD9Anm.jpg) If you did it with one hole, no air would get in, and it would be difficult to get the liquid out because air would not get behind the fluid to replace it. So a good blood-sucking design would need to provide not only for a hole to withdraw blood but also a hole to let air in. And since animals are natually symmetrical, one set of these hole-makers on each side. This is shown in actual vampire bat teeth: [![enter image description here](https://i.stack.imgur.com/cfF2Y.jpg)](https://i.stack.imgur.com/cfF2Y.jpg) I can just picture the blood draining into the bat's mouth through those two round gaps created by the arrangement of those four fangs. Air goes in toward the center of the bat's mouth and the blood gets sucked into its corners and down its throat. Eww. ]
[Question] [ So I'm creating a world in which humans have a close sister species very similar to the Japanese [Nekomimi](https://en.wikipedia.org/wiki/Catgirl) seen in anime and manga. Eventually, the humans turn on Nekomimis, perceiving themselves as superior. I'm not concerned with how Nekomimis actually came to be (handwavium can apply here), but I would like them to behave fairly similarly to humans, but different enough that humans would eventually want to cast them out as outsiders - despite our love of cats as proven by the Internet. ![illustration](https://66.media.tumblr.com/5e17155eba7c3f385a26cf38c748e9bd/tumblr_mwrm1vqt781t3q50oo1_1280.png) I was wondering how their realistic biology could work, my current framework is that: * They have a tail extending out from roughly the equivalent area as on a cat. * Their ears are similar in style to a cat's, in that they turn to face sources of noise, rather than human ears that don't move and they only have one set of ears, unlike some depictions. * Any areas that would be fur (such as a tail) or hair (like our head hair) are the same colour. * They can eat the same food as humans and are omnivores. I'm also looking for any ways that Nekomimis would be better suited to some jobs than humans due to their biological differences. [Answer] The term "Neko" in Japanese literally means simply "cat" without further elaboration and also has a slang sense to refer to the submissive partner in a homosexual relationship. So, you may want to think twice about using that term with the belief that it would be understood unambiguously to refer to a "furry" humanoid with cat-like aspects. Unlike dogs which are omnivores like humans, cats are obligate carnivores and that fact has a lot to do with the reason that cats are less full domesticated than dogs and are instead more symbiotic with human historically than they are truly domesticated (at least until quite recently, cats cohabited with humans from about 9,000 years ago and just started to be kept as true pets in the Middle Ages). Unlike dogs, cats could be trusted to guard grain stores because they would eat the pests such as mice and rats, but would not eat the grain itself. Also, dietary differences are such a classic cultural distinction even between humans (kosher, vegan, paleo, no beef in India, etc.) that it would be a shame to waste the obvious opportunity. Dietary differences are used to great atmospheric and plot effect, for example, in the [webcomic Orange Marmalade](http://www.webtoons.com/en/romance/orange-marmalade/list?title_no=97) (which is currently being made into a live-action TV production). Cats and dogs often have mixed color schemes, but if mono-color does it for you or has aesthetic appeal, cool. One animated series, RWBY, has a scene where a discriminated against furry recounts a historical battle in which humans tried to ambush them at night, but their superior night vision caused them to prevail. A tendency to be nocturnal has wide application. So does a natural hunting instinct and a good sense of smell. A sense of balance and a tail might be an edge in construction trades and work in tree removal and fruit harvesting. Your Nekos might do well as sommeliers with an evening oriented lifestyle, a fine sense of smell and a tendency to want a pleasure-filled life fitting well with a career as a wine steward. And the "cat house" has also always been a term associated with a particular profession that tends towards the nocturnal. In Keri Arthur's City of Light series, genetically engineered humans with werecat DNA and werecats are both stealthy warriors. Another webcomic to look at for inspiration as it is inhabited entirely by furries is [Replay](http://replaycomic.com/). A nocturnal lifestyle, a feline fetish for cleanliness and a subordinated position in society might also make a good fit for janitors/maids in the society. A reputation for being lazy and anti-social and not team players could fit into the subordinated role in society piece. It could also lead to lower levels of educational success because of trouble staying on task in conventional educational settings as opposed to independent study. Conventional wisdom has it that cats are more attuned to weather changes, earthquakes, and ghosts than humans. [Answer] The tail thing is pretty easy. Humans already have a vestigial tail structure called the coccyx. No ape has a tail, but plenty of monkeys do so there are clearly latent genetics we can exploit in order for humans to grow a tail later in life. I'd suggest basing the tail on New World monkeys so it is prehensile, which is a much more useful adaptation (but not really cat-like). At any rate, extending the tip of the vertebral column and attaching some musculature to drive a tail is fairly trivial. Rotating cat ears won't help you much with human skull shapes. The ears are on opposing sides of the head, rather than on the top, so you can't rotate them to get a stereoscopic auditory input. You CAN enlarge the pinna (outside of the ear) so your catpeople can hear better but only what is in front of them, they will have to rotate their head to pinpoint sounds. Trying to extend the human auditory canal up to the top of the head would be an extreme feat, and would distort the skull significantly. But you can boost human hearing into cat frequencies and increase the balancing functions of the inner ear, though on a bipedal organism I'm not sure it will help as much as with a quadruped. Boosting hair growth to cat-like levels is simple enough (although we really can't increase the number of hair follicles [hair club for men's claims to the contrary :)]) but you will run into overheating issues and nasty funk from sweat. Furred animals don't sweat like humans. So catpeople will either have to operate in colder areas, douse themselves in water to provide evaporative cooling (this is one of the reasons cats lick themselves), or develop a long tongue for panting. Cats like a higher body temp than humans, but trying to do that would require a significant alteration is a lot of biological functions in a human. Another possibility is less fur over key areas, like the armpits and groin, to allow for some areas for sweating. Humans still have hair in those areas to RETAIN heat, but if you have a permanent fur coat the opposite situation could arise. Hard to imagine situations where cat adaptations would help in ways that technology wouldn't. But if these cat people have superb balance (helped a bit by the tail) they could be high elevation construction workers, cleaners, etc. Anything where walking along narrow surfaces is required. Improved frequency hearing could be helpful in detecting victims buried under rubble/avalanches, maybe hearing signs of mechanical stress in machinery (?), and possibly operating in low light environments since they may have a very weak form of echolocation. There are other cat attributes like the reflective cornea for improved low light vision, increased visual response to motion, and predatory instincts that could certainly cause some level of discomfort from humans around these cat-people (especially if they are aggressive). They could also be territorial and a bit anti-social, especially a dominant male towards other males. No need for whiskers since the human shoulders are far too broad to ever allow the body to slip in behind the head (I've heard whiskers are to let animals know if they can fit their body through a hole) and at any rate, bipeds don't lead with their head anymore, they use their hands. [Answer] You have a few realistic options: ## Human with cat ears, but human shaped skull This would cause the ears to be placed on the side of the head, an odd placement for "cat-like" ears, even if the ears are shaped the same as a cats. As most humans are still capable of moving their ears a little bit, you would simply need slightly more developed and perhaps better placed muscles in order to achieve the similar range of motion. (I wasn't able to move my ears when in elementary school until I met someone who could, and I actually spent a few months training myself until I could move my ears too. I still can to this day.) ## Human with cat ears, minimally modified skull Moving the ears to the top of the head, while otherwise retaining human characteristics, would require some alterations in brain shape, skull shape, and moving the connections between the ear and brain to the appropriate location. This may cause interesting side-effects. ## Anthropomorphic Cat This would start with the cat physiology, and modify it just enough to be a true humanoid, ala TMNT bio-energy points. One consideration would be the spine and pelvis. The spine in a cat has muscles running along the vertebrae, which allows for the incredible twisting motions cats usually display in mid-air, or when contortion-snuggling. If the pelvis was altered to be 'locking' like a humans, then they would have an easier time standing upright, however lose some flexibility. If it was not altered, then they retain the full flexibility, but would get tired of standing up for long periods of time. However, you would have the head and ears without any further alterations. ## Tails Tails shouldn't be too much of a stretch, either way. Humans are occasionally born with actual tails, a well documented phenomenon. The catch would be that a human tail wouldn't be very mobile, as it would lack the extra muscles alone the spine (and tail) that a cat has. Perhaps a hybrid musculature, or the anthro-cat style would work best. ## Occupations Cats are "sprint-sleepers", a term which here means that they take short sleeps, interspersed by periods of wakefullness. During the day, the sleeping periods are longer, and the active periods are shorter. During the night, being nocturnal in general, they are mostly awake, with only short periods of rest or sleep. This would lend towards nocturnal jobs more than day jobs, unless said jobs are intermittent or sporadic in nature. The reflective retina grants better low-light vision, though it can be used to spot them in the dark as well, again lending towards jobs during the night or low-light conditions. Cat's claws allow them to climb up things easily, but not down, due to the shape and attachment points; hence the cat-stuck-in-the-tree stereotype. Jobs requiring climbing might be applicable, so long as there is an alternate method of getting down. Acrobatics in general seem a good fit, and anything requiring flexibility, balance, and a lack of fear of heights. It is true that the whiskers allow for a more precise sense of if an opening is large enough for the head or not, so underground work is also not out of the question. Heightened sense of smell (at least compared to a standard human, due to the vestial vomeronasal organ in humans which is still fully developed in cats) is a possibility. This is also why cats will make that odd, almost hissing-looking face when they smell some things, so as to allow air to pass over said organ. Wine-tester, food-tester (poison-tester?), artificial-scent tester, air-tester, and so forth might all be possible positions. [Answer] A species like that would not evolve naturally alongside humans, because evolution does not produce homologies (similarities in form unrelated to function) in lineages that don’t share a common ancestry. The common ancestor of the hominins didn’t look like a cat, and therefore no hominid would coincidentally end up looking superficially like some completely different branch of the tree of life. Horizontal gene transfer (such as having cat genes spliced in by a retrovirus) doesn’t work from a hard-SF perspective either, because genes don’t work like Lego blocks. If you want a hard-SF explanation for them, then the Nekomimi must have been genetically engineered, and that gives them a history that probably explains their social status. If, for example, they were originally created to be domestic servants and companions, that might explain why they are considered inferior, or if they were originally assassins, spies and infiltrators, why they are still feared, even if that was generations ago and most just want to lead normal lives now. I don’t get the impression that scientific accuracy is a major concern for this story, so I wouldn’t suggest you take the more evolutionarily-plausible path of giving a human-like species atavistic monkey-like traits. A small number of humans really are born with atavistic tails! You said you were willing to handwave their looking like cat-people, though, so this doesn’t seem to be what you’re after. If you want the Nekomimi to exist naturally on another planet with a hard-SF rationale, then I think you need to reveal that the true natural history of human beings is different than people thought back in the early 21st century. Think Larry Niven’s *Protector*, where *homo erectus* was really an alien species that depended on a Fruit of Knowledge to gain sapience, lost it on Earth, and all the apes are really their descendants. If both apes and felines are really descended from aliens and their pets, then maybe they do share a common ancestor, and the Nekomimi simply retained more of those ancestral traits. Any apparent similarities to humans are the result of a parallel process of neoteny, and therefore convergent evolution, not homologies. But it’s still more plausible they’d look like Kzinti than like people with cat ears: they would be just as related to chimps and gorillas as to humans. If they have to have lived on the same planet for as long as anyone can remember, then maybe they all forgot they’re the descendants of a colony ship or an apocalypse. Or you could just say they evolved in different places on the same planet and handwave it. You should be able to get away with one handwave. [Answer] I'm not sure how you want your story/world to be, but skyrim seems to do a great job at creating a species based on cats. <http://elderscrolls.wikia.com/wiki/Khajiit_(Skyrim)> The Khajiit are in the game traveling salesmen. They are also used as assassins: > > In addition to standard elven strike teams, the Thalmor also employ Khajiit assassins when stealth is required. > > > If you enter the game you get a boost on your sneak skill. You could use this information to give your cat species a roguish lifestyle or personality etc. In the game they are a minority, facing racial slurs by inhabitants of cities in Skyrim. [Answer] Since you like Japanese anime, all these questions were answered with some detail into the science factor in the anime [Utawarerumono](https://en.wikipedia.org/wiki/Utawarerumono) and its sequel. They did an amazing job. It could feasibly give you ideas to watch the series. I can't count the number of anime I've seen that offer various explanations, such as the anime *K* where something happened in WWII that made it possible for a human to become a cat and switch back and forth between human and a neko, though a bit more supernatural than the scientific approach. Similarly in other anime they use gods, or *Kami*, as a reliable explanation, since their cast of celestial deities are quite vast, both based on Shinto as well as Buddhism. Also youkai - monsters or demons depending on the source you refer to - can explain the nekomimi and others like it. If you just want the one species, you can stick to that, although I've seen multiple anime that have a plethora of anthropomorphic animals in human form. Shapeshifters could potentially also explain how these human-like beings came about. You'll find it in a lot of anime where these non-humans change their appearance or hide their appearance just enough to appear human, though when hungry or excited their ears and tails tend to show their emotion. Although some may consider it more the realm of fan fiction than actual science fiction I wrote a story where a group of beings evolved on Earth alongside humans. I based them mostly off of stories of Youkai. I tend to love the Kitsune, more, but all of them are equally intriguing. As to a plausible scientific reason... I'm not sure but you might be pushing the boundaries of "believable" a little unless you choose something along the lines of Utawareremono and make animal DNA a necessary evolutionary step in the continual existence of the human race, created by scientist of course.... in that case it would be the ones with animal like attributes who would be the next step in evolution, not humans. The humans, fearing being wiped out by this newly evolved lifeform, could still be afraid or cruel to those they deem different. [Answer] Well, the differences you describe are largely cosmetic, so I can't see any immediate difference that could lead to occupational opportunities. The tail may help with balance, say acrobats or such. The ears might make them more alert to small sounds, which is potentially good for something like security, patrolling, hunting certain animals. Though, these aren't gamechangers for their species If you have stuff like cat's eyes, these are great at adjusting quickly to light conditions, but they don't have great longevity compared to human eyes. If you want to have stuff like transformation and magic associated with bakeneko, then that tends to exit the realm of biology. What you described so far seems fine. [Answer] If you don't want to do magical stuff, but want it to remain slightly more 'scientific', you could lean on a later hormone flux that would fire off a sleeping gene (or genetic defect possibly caused by historic genetic tampering for a variety of reasons) and cause the coccyx to lengthen, ears to migrate and grow pointy, hair to sprout, etc. It would be a long, painful process, I imagine, especially growing the tail, which the [kid from India who had his removed](http://www.mirror.co.uk/news/world-news/indian-boy-8-inch-tail-8984067) noted. With a hormonal or 'age period' introduce a variance of those who have experienced incomplete transformations of catlike appearance, (And, even those who went too far or cases of those no longer mentally entirely human) perhaps even making a 'Cat trait beauty standard' thus, if you fall within X lines you are considered 'superior' (If you tie it into a late teens, early twenties range, the sterotype of the unchanged, are viewed more as 'children', and treated with similar lack of trust or knowledge of children -so more pitiable than slave-like. In this case, though, those who have gone too far are treated like mental patients, institutionalized and hidden from public view, even if their exterior is too far, their minds could be in one piece.) If you don't want to make it a long, drawn out process and want *BAM -KITTEH!-* and want to justify a complete reworking of musculature, etc consider using a cocoon. ]
[Question] [ There are a number of movies, books and TV shows where the villain wants to kill nearly everyone on the planet because of ecological concerns: there are too many humans, we're using the global resource stockpile way too fast, we're polluting the planet, other species are going extinct,... In many of the movies on this subject, the villain usually has a plan which is essentially "save those with money, kill everyone else and rebuild the earth with them". It happens in Kingsman, at least 2 Bond movies, several other TV shows/movies/books. the question is though: Would that actually be a decent solution for reducing the ecological pressure put on Earth by human activity? Considering both the ecological footprint of all the humans that would die as well as the many processes that would fail catastrophically if humanity was no longer able to maintain them (factories, power plants, similar locations where humans are needed to maintain or at least supervise machines to ensure they don't fail catastrophically with loads of fire and pollution), what would the net effect on Earth's ecology be of killing 99% of the population in a way that keeps most of the infrastructure intact? I'm talking about a singular culling of over 90% of the human population, a one time only event while the survivors put in the effort to ensure the future generations don't break the bank again. --- I have read [Why not kill off most of humanity?](https://worldbuilding.stackexchange.com/questions/54832/why-not-kill-off-most-of-humanity). That one is focused on the plan failing and a story-based reason why it would fail. This question is focused on whether the plan itself has any merit, regardless of motivations for executing or halting the plan. As such, I don't think it's a duplicate. [Answer] ## Situation: * Humanity is killing the planet ## Aim: * Reduce load on the planet by reducing population * Maintain current lifestyle for the survivors ## Options to achieve the aims Starting with a **standard bad guy option**, I gather all my wealthy friends to my volcanic fortress and kill everyone else. * Outcome: Terrible. Wealth is mostly real estate and companies. Without workers for the companies, without a market for their products, the companies are worth nothing. Without demand for the space, the real estate is equally worthless. Also rich people are mostly useless. They have no physical or practical skills, none of them could build a hut, a boat, or a fishing rod. **Geographical option**, I want to survive this so we'll draw a circle around Western Europe and kill everyone outside it. * Outcome: Better than the first. Western Europe is, on a global scale, just a bunch of rich people. There are now a lot more practical skills and knowledge available, a good chance that the survivors won't rapidly return to the stone age, but they certainly won't be able to maintain the disposable culture as too much of it is made in Chinese factories. **Pseudo random option**, just kill 99% of people evenly distributed globally. * Outcome: Everybody is dead of the disease caused by so many rotting corpses around them. The rest are too traumatised to try to survive. Economies collapse, lifestyle is lost. **Sarcastic option**, this is the only way you can achieve both goals as for all other purposes they're mutually exclusive, kill everyone who has ever held a mobile phone. * Outcome: The isolated tribes who've never been contacted carry on as before, they maintain their skills and lifestyles without being affected. The consumer culture that's causing the vast bulk of the damage is wiped out. It'll take thousands of years before the global population is back at a technological level where they can start doing that level of damage again. *Perhaps you could just teach people about the damage their way of life is doing to the world and that they should be more careful about disposable tat and plastic packaging.* [Answer] Perhaps the simplest answer is not to kill anyone, but to stop more people from being added. Bonus points for reducing the rate of replacement. So China's one child policy, if implemented globally, would easy solve the issue in 2 generations. Sure, you'd have other issues to deal with - mainly an ageing population that requires either less pension, longer working lives, or automated elderly care (all of which are solvable - pensions are dealt with by keeping elderly people working on a part-time basis, which happens in 3rd world countries anyway, or keeping them working longer as I personally know lots of people forced to retire when they didn't really want to) The net result is that the population slowly reduces. Children are better educated (as there are fewer of them and they are now considered more precious and important to be good citizens) and they in turn will have fewer children anyway because they are better educated! (This is happening in China, they will have a demographic problem in the future as, apart from the stupidity of old cultural thinking that boys were better, thus skewing the male-female ratio to an imbalanced state where the total number of male-female pairings for reproductive purposes will be constrained by the lower number of females, the female children that are born into this system have been educated and expect careers and perhaps, not even to have large families like their parents or grandparents did. So ultimately, the population will slowly stabilise, and will be an all-round "better" set of people. Your trouble is persuading everyone to do this, but the easiest way is via money. child benefit for the 1st child only and that's it, no more, will have an effect on many; in other places, families with 1 child will be entitled to government assistance for (say) elderly care so they do not need to have loads of children to look after the parents. You could ensure that 1 child families are first in the queue for state housing or jobs, etc. You don't even need to mandate 1 child, just nudge the population to have fewer children via these incentives, depending on how quickly you want to change the planetary population. In 20 years time, there will be fewer children, in 40, fewer adults, in 60 the problem will be solved. If are a villain who wants to force it on everyone, then start researching a GM virus that makes half the population infertile. Drop it in the water, job done. Make sure to double test it first! So while this doesn't kill 99% of the population, it effectively does the same job, only a lot slower by employing age to do it for you. [Answer] Plan has merits (we are surely too many by at least an order of magnitude), but is also very stupid (especially the part about saving people with a lot of money). * You need high population (100M+) to sustain current technology. * You need sizable population (1M+) for both biodiversity and cultural specialization. * Rich people wouldn't be able to make machines/research/industry work. * Without other constraints population would bloom back in a matter of generations (it took less than five years to cover-up losses in WWII). * Civilization fall, if happens now, would be difficult to recover from because we depleted most of readily available resources. If you want to "save the world" you need a better plan ("bad guys" in movies are often quite dense). [Answer] ### Yes, an *organized* extermination of 99% of humanity could be the *start* of a viable solution. The obstacles could be overcome. Speaking in super-villain mode, 1% of roughly 7.5B is 75M. That is enough to maintain a modern society if you collect them all together and protect them from the extermination. It is larger than the population of England, and 90% the population of Germany. It is 3.5 times the total population of Norway, Denmark and Sweden put together. Really, a million people is more than enough to keep a modern city running, so dozens of cities could be established, around the world, to be close to the resources that cannot be moved (climate, arable land, fisheries, mining operations, etc), and could be kept running. We could maintain the infrastructure **of those cities** and grow the food, produce the energy, run the factories, etc. Especially with all the world's resources, parts and stockpiles untouched and available for the taking. I don't have to depend on scavenging; the actual factories making things like microchips, tablets, farming equipment, etc can be used, we can keep plenty of people that know how to run them, design them, and program them. The biggest caveat would be population control, but that can be handled too. I can demand genetic screening and abortion for abnormalities, also for parentage. Have all men and women register DNA, and continue to do so at birth for future generations. Parentage becomes a certainty. For both men and women, becoming the parent of a child costs them each a point, and each person has two reproductive points, after which they are surgically sterilized. I'd let them freeze sperm and eggs before sterilization, so if their child dies before adulthood the parents each receive a reproductive point that can be accomplished by in-vitro fertilization, with the same partner or another (e.g. they don't have to stay together). It makes no sense for me to keep the wealthy, unless I just need them to finance the operation. I have been around dozens of very wealthy people (My skills are particularly useful to them) and most of them are not highly skilled, not great managers or businessmen, and not that intellectually gifted. The source of most of that wealth is a lucky strike (as in striking gold), with some kind of entertainment, an invention that caught on, being born to a wealthy patriarch, having the looks, charisma, voice, or athletic ability to become a star (which does require some skills but not a lot of intellectual firepower), or just being in the right place at the right time or having personal friends that did, so they got in on the dirt floor of the Microsofts, Intels, Apples, Googles and PayPals of their day: One genius with 500 lucky multi-millionaires in their wake, because they got stock for a penny that became worth 10,000 times as much, with no particular genius on their part. (e.g. Bill Gates first receptionist became a multi-millionaire on MSFT stock). What I want to preserve is talent, expertise, intelligence and problem solving ability, in hundreds of disciplines, and I want to preserve the ability to **teach** those things to future generations. So if that turns out to be a rich person, fine, if not, I'll take the John Deere engineer that knows how to keep farm machinery running, and everybody else it takes to continue the modern methods of putting bread on the table. Most of the world would eventually crumble, which is what we want. Return it to forest. Most of the people would rot and die. But ***they were all going to die anyway in the next 100 years,*** so whatever CO2 and pollutants they cause are just a pulse, exactly what they would have produced by eventually dying *anyway*, and less than they would produce if left alive: Their day-to-day CO2 production (their carbon footprint) comes to an end, thus saving an average of about 40 years of life. Within a few decades, as the parts of the world we don't use return to vegetation and forest, the bodies of the dead are naturally recycled into what we actually want: long lived trees and plants that absorb CO2 and produce oxygen. For any particular places that we want to use, the dead can be removed and buried at sea as fish food, eventually helping to recover fisheries and sea life. The oceans and atmosphere would recover, with 99% less pollution, and 99% more forest to absorb whatever pollution we produce. We don't have to give up fossil fuels, our problem is not exactly pollution, but too much pollution so we exceed the absorption capacity of the Earth. Analogous to salt: Eating a pound of salty potato chips won't kill me, eating a pound of salt could produce hypernatremia, salt poisoning that can give me seizures and kill me today. Yes, exterminating 99% of people can work. There is plenty of land near the northern and southern poles that will still be cold enough for us to ride out the worst of global warming if it ramps up severely, for a few centuries. (Of course enough heat kills everybody and everything, we cannot recover from *anything*.) But I [the super-villain] can't just leave the survivors where they are, that would return them to medieval subsistence living almost immediately, or even hunting and gathering. I need a program (and hundreds of people, but I can hire the few dozen leaders I need to recruit and run them) to identify and immunize those I wish to keep (perhaps without their knowledge). Then I need a plan to either have them already be in the right place at the right time, or a plan to protect them and get them there (to one of my 75 sanctuary sites) once the pandemic begins. I believe both modern civilization and humanity could survive indefinitely with a population of 75 million people. Or with mandatory birth control, whatever we compute as a comfortable carrying capacity of Earth for humans. I would likely spread out the space occupied by about double, and make living spaces *much* larger. Crowded and towering cities are not at all a necessity with modern transportation (electric rail and cars), there are only a very few practical reason for a building to exceed three stories if horizontal space is not an issue; it is far easier to build, maintain, and demolish such structures. (Some industrial or scientific equipment is necessarily very tall, housing it is one reason to go above three stories). [Answer] The logical solution would be to wipe the entire populations of every nation on Earth except for, say, Australia. The weapon of mass destruction of choice will be the equivalent of a neutron bomb that only kills human beings, leaves all physical infrastructure intact and doesn't harm any other lifeform on the planet. Although we could probably do without bedbugs and head lice. \*\* The rest of the planet and its infrastructure would now be a vast pool of resources for the Australian population. Australia is left as a fully functioning society with an intact infrastructure, all its social, economic and political institutions functional. Certainly there will be need to be some adjustments. The manufacturing industries for aircraft, vehicles and shipbuilding will need to be expanded and developed. However, colonizing the empty nations of the world and taking over their resources like oil, minerals, crops and livestock plus their industries will be a straight forward exercise for an expanding Greater Australia. Instead of eliminating 99% of the world's population globally, a wily and thoughtful ecologically minded megalomaniac would find his task of saving the world from a pestilential human species would be better served by annihilating the populations of most of the world's nations and simply saving one nation intact. As shown in this example, Australia would be ideally placed to be that nation, to be home of the surviving 1%. Would that build a newer, better world? You can bet your life it would! \*\*: There is one small caveat. The ideal weapon of mass destruction described above is an utter impossibility. Any megalomaniac contemplating such a project will have to accept a little breakage in achieving their objective. [Answer] In short, killing off humanity would be an effective solution (in the medium term), but not an ethical one. There is no doubt that humanity's numbers are having an effect on the ecology of the planet; science has proven that climate change is real and that the environmental concerns are complicated by our sheer weight of numbers. Ironically enough, killing off ALL of humanity has higher ethical merit than selecting a few to survive. If the problem is humans, then wiping out the entire species is a permanent solution to the problem and solves the moral implications of being the person who gets to choose who survives. If we do that though, what was the point of it all? So we go back to the idea of a few select survivors. How do we choose them? Intelligence, physical fitness, skills? Genetic considerations? It's an ethical minefield because you're not really choosing who survives; you're choosing who dies. For the sake of argument though, let's assume that you DID kill off 99% of the population, and you could keep the infrastructure running (you couldn't) and that the economy didn't completely collapse (it would). By my estimates, disposing of that many bodies via cremation would generate nearly 3 Billion metric tonnes of greenhouse gases, and would take somewhere in the order of 7 x 10^17 joules of heat energy, and approximately 21 Billion cubic metres of natural gas to complete. Sure, it's a one off cost, but you're still adding to the problem in the short term. When you stop and think about it, this is a drastic solution to implement without at least considering the alternatives. In the developed world at least, birth rates are already dropping. In Australia, the only reason why we have population growth at all is immigration. It is a similar story in many other developed countries and in China for instance, the one child policy is leading to a runaway aging population problem, where in 20 years or so the burden of aged care will be far and away the highest cost on the state purse and may require a significant percentage of the working age population to undertake. If the under-developed countries of the world were brought up to the same education standards and accepted women in the workforce as a mechanism to effectively double their economies in a few short years, birth rates around the globe would reduce and no-one would have to be killed. This would introduce other social and economic problems, but couple this with efficiency technologies and other measures already underway and you've got the makings of a potential solution that doesn't involve mass murder. Put another way; extinction is a pretty big lever to control climate considerations. Perhaps it's wise to investigate some of the smaller ones first, especially as scientists are already working on these issues today. [Answer] Someone already did, though for different villainous reasons. Still, the effect was profound ;) As discussed in a number of research articles published since 2011, e.g, <https://news.mongabay.com/2011/01/how-genghis-khan-cooled-the-planet/> Gengiz Khan's military campaigns removed about 40M people from the chessboard, and forests grew back where they were once removed to make way for plowing fields. Since his empire lasted for many decades, maybe 150 years, the effect of permanently depopulated areas was sufficiently long (compared to plagues and other mass extinctions after which populations bloomed back). This allowed for the world ecology to shift noticeably. Some researchers claim he is still the one single greenest person, in the aftermath. [Answer] ## Short term: the transition phase. Local disasters. Unless the killing is well managed, there will be **localised ecological disasters**. Nuclear power plants need a power supply to prevent nuclear accidents. Damaged ecosystems that barely manage to survive because continuous human management compensates for prior human damage, will temporarily see increased imbalance: think of stray cats or deer overpopulation until larger non-human predators recover their long-lost habitats and restore the balance. Hydro dams may collapse, oil refineries and storages may burn, and rusting cars will litter the country. Preventing this would require a coordinated effort. I suspect that when a pandemic kills 99% of the population, such effort would be doomed to fail. *Mankind is ending. To prevent pollution, please shut down your industrial plants and bring your car to the nearest "recycling" centre*. It's not going to work. There *will* be short term ecological disasters on various scales. Of course, there will be tremendous disruption to civilisation as well. ## Long term: ecological harmony, sustainable development **It will work.** Let's assume the 99% killing is uniformly random. Humanity will survive and be fine. There will be more than 650,000 people left in the UK, 3 million in the USA. They can survive on stockpiles until they manage to clean up the mess and rebuild society. Unless a job is so specialised that there's less than 100 in the UK, there will still be people for every task that needs doing. Crucially, the knowledge on which our civilisation depends is not lost. Plenty of farmers, teachers, doctors, nurses, cleaners, barbers, car mechanics, carpenters, are left. We will lose some services, at least temporarily, that rely on a very complicated supply chain of highly specialised labour. It might be a while until we can replace our ageing weather satellites. The survivors may have to do without GPS and satellite phones. Most countries probably won't be able to rescue any of their nuclear plants. Science will slow down dramatically, as most surviving scientists will find they're now the only specialised in their field worldwide. That's a step back, but hardly an imminent threat to humanity. The standard of living will not take too much of a hit. Therefore, the fertility rate will remain low enough to prevent human population to ever count in the billions again. To recover the electricity supply, the survivors will probably prioritise solar and wind over coal and nuclear. Not because they want to save the seals, but because repairing a windmill is a lot less nasty than working in a coal mine and a lot less specialised than a nuclear power plant. Existing capacity of wind, solar, and hydro (assuming the dams survive the transition period) will be plenty to meet the needs of the 1% survivors. The effect will be lasting ecological recovery. After the disastrous transition phase, ecosystems will recover, ozone depletion will halt, air pollution will cease, as will climate change and deforestation. Ocean acidification is no more. Peak nitrogen or peak phosphorous is no longer a worry. Factory farming might not necessarily cease, but in absolute terms the amount of antibiotics used will drop by 99%. There will be plenty of freshwater for all. The Aral Sea will recover and the Colorado River will once again reach the sea. Although there are ethical, legal, and practical reasons to object to killing 99% of humanity, from an ecological point of view, it would be highly effective. If you agree, join the [VHEMT](http://vhemt.org/) ;-). [Answer] The short answer is that you have to kill off most people and then enforce an environmentalist dictatorship upon those left. I strongly recommending reading about [Pentii Linkola](https://en.wikipedia.org/wiki/Pentti_Linkola), and am surprised he hasn't been mentioned yet. His book "Can Life Prevail?" is relevant. Linkola is rather politely termed a "deep ecologist"... though "environmental extremist" is probably better, and "ecofascist" is not far from the truth. He advocates reducing the human population to 10% of its current total in order to stop environmental destruction. In his view all life has value, but both the quantity of human life, and destructive effect it has upon all other life on earth, means that the individual human life is worthless. Consequently, in order to prevent ecological destruction, he claims using WMD (biological and chemical if you want infrastructure intact) on cities, enforced migrations, birth control, abortions, abandoning democracy and capitalism in favour of an austere environmentalist dictatorship, is all required, and will protect and preserve the global ecosystem. Democracy he argues is a "religion of death", which inevitably promotes unsustainable consumerism. Importantly, it's not just killing people which has a corrective effect, but that the nature of government and society changes radically to control the destructive effects of consumerism and greed. Having children would no longer be an individual choice, and resources should be collectivised and minimised. [Answer] Most of the answers here are from the point of view of humanity and its survival. If we step aside from that a little bit and think from Earth's point of view, then we will realize human actions no matter will have minimal impact on earth's ecology over geological time scales. Life began, survived and evolved under far harsher conditions and even if we nuke ourselves out of existence it would not matter much. Earth will heal and support different forms of life until the conditions become too harsh (due sun expanding and other external factors). As far as humans are concerned, I don't think there will be much change even after a "planned mass culling". We, as a life form are programmed to propagate through reproduction at all costs and all our actions will be always directed towards this goal no matter how intelligent we get. So even if 1% of the population survives, provided enough resources are present things will quickly get back to the way it is now. [Answer] Like [NeinStein](https://worldbuilding.stackexchange.com/users/11031/neinstein) said in the [Comments](https://worldbuilding.stackexchange.com/questions/99958/killing-the-majority-of-humanity-for-ecological-reasons#comment298352_99958): a non-instant slaughter solution should be considered. A good example for this is the novel '[Inferno](https://en.wikipedia.org/wiki/Inferno_(Dan_Brown_novel))' (2013): > > The plague that Zobrist created is revealed to be a vector virus that randomly activates to employ DNA modification to cause **sterility in one third of humans**, thereby reducing population growth to a more stable level.[Source](https://en.wikipedia.org/wiki/Inferno_(Dan_Brown_novel)#Plot) > > > By sterilizing a certian percantage of humanity (and infecting all following generations), an **instant** disaster can be avoided. The shortterm affects of this procedure would differ from country to country. They mainly depend on: 1. [Birthrate](https://data.worldbank.org/indicator/SP.DYN.TFRT.IN/?year_high_desc=true) 2. [Population growth rate](https://en.wikipedia.org/wiki/List_of_countries_by_population_growth_rate) 3. [Median age](https://en.wikipedia.org/wiki/List_of_countries_by_median_age) Countrys with a currently low birthrate and a high median age would have to deal with economical problems soon. Mainly because of a missing workforce and a shortage of specialists. The need of power would decrease with the population of the country and therefore get powerplants shutdown. *Often do these countrys have a big ecological footprint.* Countrys with a high birthrate and a low median age would be able to avoid these for some time (depending on the mentioned factors) before confronted with the same problems. **Problems:** 1. A big shift upwards in Birthrate might be able to increase the population growth rate over 0% again. The probabilty of this happening depends on the initial sterilization rate. 2. With increasing sterilization rate the extinction probability increases. 3. The population growth rate probably wont stall at 0% either. The population will grow again. 4. The ecological pressure will be released slowly (not as fast as in an 99% slaughter). **Advanatage over slaughter**: 1. Most of the infrastructure is kept intact. 2. The effect on the ecological footprint will last longer (but wont be that strong). 3. We could maintain our standard of living. [Answer] The problem with killing these assholes is that it would be easier to just force them to use ecological tools. Force them to use clean sources of energy, find a solution on how to use/defuse nuclear waste, switch people to less food waste and usage of more efficient food. The problem with solution in *Kingsman* is that when most of the people die the rich ones would no longer be rich, politicians would have no one to control and no army to fight with. Their position would depreciate in value. Solution in *Moonraker* is one of the best as the sole purpose is to kill ALL humans and repopulate with selected based on their feats (DNA). So we kill humans and build another race. This is good. BUT again, the way to do that and make earth habitable and with enough food would probably take more effort than just slap all coal users, diesel burning, meat eating lovers. ]
[Question] [ Let's say I have an aquatic humanoid, vaguely like a [selkie](https://en.wikipedia.org/wiki/Selkie). As creatures that spend a lot of time in water, it would be great if they can stay under water for "a while". The human breath-holding record is over 20 minutes, but this a) is exceptional, and b) such feats typically involve a lot of preparation. What changes / differences from humans are needed to allow these humanoids to *routinely* hold their breath for, say, 5-15 minutes, and to be able to do so without significant preparation? In particular, what of these changes would be "noticeable", either to a human observing such a creature, or to a human that was somehow magically transformed into such a creature? Some rules: * These creatures are mammals. Not birds, reptiles, insects, or plants. Not cyborgs. Not something with exotic anatomy and physiology. Preferably no nano-machines or other technological augmentations are involved. (I'm slightly less adverse to outright magic, but would still strongly prefer to avoid it.) * They look superficially human except for their noses, which resemble the nose of a seal or sea lion. (A longer "snout" is also okay, though I don't expect it to matter.) * They should be able to remain underwater for repeated stretches of at least five minutes after not more than thirty seconds of breathing (shorter is better). Ideally, they should also be able to stay under for 2-5 minutes after a single somewhat-deep breath if they've been above water for at least a minute or so beforehand. * They only need to be able to do this in "warm" (~25°C) water. If it works in colder water too, that's great, but not necessary. If changing this requirement to 30°C helps, that's acceptable. * Along with the last point, while they may have a bit more fat on average than a "healthy" human, it's well within e.g. American averages. * They don't generally dive very deeply (only ~5m), so if the target "several minutes" is unattainable at greater depths / pressure, that's fine. * This all needs to happen during *moderate* physical exertion (swimming, but not strenuously). More extreme conditions (e.g. panic, strenuous exertion) are allowed to significantly reduce the time they can stay under. * *Absent* such extreme conditions (or being stupid about trying to push how long they can stay under), this should be about as dangerous for these creatures as similar feats are for dolphins and pinnipeds; i.e. minimally. Doing this day after day should not be significantly hazardous or lead to long-term health problems. Basically, I'm looking for a humanoid that can dive, swim, and generally loiter underwater (in terms of time, anyway; mobility-wise they'd be essentially human) like a pinniped or a dolphin. ...and no, [this question](/questions/169598) doesn't really help. Good answers should: * Give at least an overview of the physiological differences. * Explore (at least briefly) what such a creature needs to do to prepare for a dive. (The goal is something like "take a *few* deep breaths".) * Explore what such a creature would experience during a dive, particularly how (or if) the experience would differ from a human swimming underwater. [Answer] ## **The Bajau People** [![enter image description here](https://i.stack.imgur.com/i51FQ.png)](https://i.stack.imgur.com/i51FQ.png) What you're looking for might already exist in a group of real people in southeast Asia known as the tribes of Sama-Bajau or the "Sea Nomads". They live in a culture where diving is a way of life and spend many hours underwater diving daily. Over a long period of time, they seem to have developed some adaptations to help them dive better, as many of them can easily hold their breath for minutes, with some up to 13 minutes. The main feature that allows this is an enlarged spleen, up to 50% larger than normal that can hold hemoglobin rich blood and release it during the dive into the bloodstream. Wikipedia states that they also have genes that affect the constriction of blood vessels and others that regulate the PH of blood when carbon dioxide gets absorbed into the blood stream under hypoxia conditions. Another people similar in the region, known as the Moken, seem to have adapted better underwater vison than Europeans. So what you want may very well be in the range of human abilities as we know it. <https://en.wikipedia.org/wiki/Sama-Bajau> [Answer] --- **Myoglobin to store O2.** <https://en.wikipedia.org/wiki/Myoglobin> > > Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein > found in the skeletal muscle tissue of vertebrates in general and in > almost all mammals. Myoglobin is distantly related to hemoglobin. > Compared to hemoglobin, myoglobin has a higher affinity for oxygen and > does not have cooperative-binding with oxygen like hemoglobin does. > But at the core, it is an oxygen-binding protein in red blood cells. > > > High concentrations of myoglobin in muscle cells allow organisms to > hold their breath for a longer period of time. Diving mammals such as > whales and seals have muscles with particularly high abundance of > myoglobin. > > > --- **Move CO2 excretion to the kidneys.** CO2 already equilibrates with HCO3 via carbonic anhydrase. <https://en.wikipedia.org/wiki/Carbonic_anhydrase> > > The reaction that shows the catalyzation of carbonic anhydrase in our > tissues is: > > > CO2 + H2O -> H2CO3 -> H+ + HCO3- > > > HCO3- and H+ are water soluble and the kidneys can get rid of them. Your people will need to make bucketloads of urine as they swim around. Fortunately they have a lot to drink, and they are underwater. [Answer] They need some way of storing more oxygen than normal (several haemoglobin mutations would allow for that, even if the most efficient would give them orange blood, and a different complexion). This plus a larger blood mass can easily account for double the endurance. They also need to get rid of CO2. They might have specialized tissue at the back of the nose: when diving, they take in water from the nose, and eject it from the mouth, while the lungs remain sealed. Without the CO2 reflex, you can stay underwater much longer. You'll need a different reflex to warn about oxygen depletion - maybe spleen pains. Some oxygen can also be absorbed from the water this way, especially in cold water. Then they need a slightly different anaerobic metabolism, to allow a greater lactic acid build-up. The lactic acid can be stored or expelled in the water through the skin. This will reduce the oxygen requirements, at the expense of increased glycogen reserve depletion. [Buoyancy control](https://en.wikipedia.org/wiki/Swim_bladder) can reduce the energy required for swimming. None of these changes is externally visible, and they should allow even more than the required 15 minutes. [Answer] I think one of the main problem that prevent us from holding our breath for long is the CO2 trigger (I am sure it has a better name but I don't know it) which forces us to breathe when the saturation level of CO2 in our blood stream reaches a certain threshold. This is why some people drown, because they instinctively take a breath of water, pushed by this reflex which made them "hungry for air", even though their lungs still had some usable oxygen. The threshold for this mechanism should be moved to a higher set point. Part of the training of a deep apnea diver is dedicated to delay the onset of this reflex. Another mechanism that would need to be in place is the limitation of blood flow to unnecessary organs during the dive/apnea, in order to optimize the oxygen usage. [Answer] Regarding depths, as a casual free-diver I can assert that at roughly 10-12 meters underwater it is a lot easier to stay down for a long time. I suppose this is thanks to compression (with about 1 atm pressure) of the chest so your buoyancy lowers and you don't expend strength and oxygen to keep pressing yourself down in order to "just float", as happens at smaller depths. So if fins or anchored rope helps me get that far down quickly, I can spend maybe twice as much time actively snorkeling than at a couple meters under surface. It does take a greater effort to swim back up though :) but jumping from seabed, or a few flaps with fins, take care of that. One wet-suit I had had positive buoyancy, so diving in it was a very exerting effort :) I did not have weight belts, they could make sense. In colder water however a wet-suit can make a great difference for staying in water longer (spending less sugar/fat to warm up instead of to move), and note that deeper layers are often much colder than the top foot or two. In many waters in fact having an extra layer of skin can make sense also as protection (think poisonous jellyfish of New Zealand/Australia region where even a silk-thin suit can save your life); swimming boots (or fins) may be important for foot protection against corals and sharp rocks. This answer and further discussion at Quora: <https://qr.ae/pGkl6J> also details how swimming suits for sports helped reduce drag and make energy spending more efficient for swimming - to the extent that superb suits were forbidden for the sake of competitive sport. I suppose it too can help your humans stay underwater longer, so can be a part of the answer even without biology modifications. FWIW, my "specs" are not stellar, though impress people nearby, with 2+ minutes sitting underwater holding on to something, or about half a minute swimming 25-30 meters across a pool (without fins). Regarding further specialization, AFAIK some fluorine based solutions act as artificial hemoglobin equivalent. There were some solutions for medical injection/transfusions, known as "blue blood", as well as ones you can "breathe" into your lungs for fancy underwater oxygen-CO2 exchange, like illustrated in The Abyss movie. As an upside, that gets you rid of an air bubble that deeper sea pressure can crush in, so you are same-density water in and out and are much sturdier (no idea if that is pre-saturated with oxygen for divers; I doubt water per se has enough oxygen solved for a warm-blooded mammal to breathe). [Answer] If the humaniods spend most of their time in the water, you could adapt the skin so it absorbs more oxygen through water than human skin. I'm not certain how to verify the stat, but I was told that about 10% of the oxygen consumed by the human body is absorbed through the skin. (The original source was authoritative but the subject of that piece primarily dealt with the effects of tarring and feathering on a human body. I'll update my answer if I locate it) Drawbacks/tradeoffs could be that that they need to keep their skin wet with water every hour/day/whatever - similar to mythical creatures. ]
[Question] [ In a world I’m building - the same one as in [Is space piracy orbitally practical?](https://worldbuilding.stackexchange.com/q/62937/627) - there are many space stations in [low Earth orbit](https://en.wikipedia.org/wiki/Low_Earth_orbit), used as orbital spaceports, each about ten times the size of the [ISS](https://en.wikipedia.org/wiki/International_Space_Station). Small shuttles bring in passengers and crew from Earth, and larger craft, docked at the stations, then bring this cargo to Venus, Mars or the Moon. At this point in time - in the year 2100, 35 years after the events of the space piracy question - these stations are ubiquitous and absolutely necessary for Earth to retain its economic and social status in an increasingly populated Solar System. However, with too many space stations, [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome) becomes an issue. The breakup of one station through an accident could quickly be multiplied, proving catastrophic for the network of stations. I think that about 100 stations could be enough to have an extremely strong trading and exploration hub. However, it seems clear that a terrorist could blow one up. Given the size of these stations and the associated ships, this could prove to be a huge problem, taking down other space stations and satellites, possibly crippling Earth's interplanetary trade. Shields to protect against small pieces of debris (e.g. [Whipple shields](https://en.wikipedia.org/wiki/Whipple_shield)) are already in use, but they aren't really helpful against larger fragments. Assuming that it is possible for someone to blow up a station, what measures can the station operators take beforehand to minimize the resulting damage? How can they prevent Kessler Syndrome? --- I saw [Dealing with space debris and Kessler Syndrome](https://worldbuilding.stackexchange.com/q/58587/627), but I believe this is distinct. That question involves clearing up other debris; this question has to do with preventative measures *before* any additional debris is created. I believe the answers to this question will be much different, as almost all of those answers suggested cleaning debris up. [One](https://worldbuilding.stackexchange.com/a/58606/627) did not, but I'm already assuming that there are sensors in place to detect any sudden debris. The problem is still one of avoiding it - not easy to do with large space stations. [Answer] So, if I'm understanding correctly, you're wondering how to prevent a catastrophic failure on a space station from creating debris that would be hazardous to other stations? If so, there are a few options: ## 1) Failure Points This is a development of a technology commonly used on aircraft to minimise the effect of a crack in the skin of the aircraft. The skin of the aircraft is built with deliberate weak points, so if there's a failure at any one point, the entire panel will break out. This prevents the damage from spreading beyond that point. In our space station attack scenario, your station would be built from modules designed to come apart under stress. Thus rather than the explosion ripping metal into thousands of sharp splinters, it would produce a few hundred soft-edged squares. ## 2) Catch the debris before it leaves I don't remember where I saw this - it was ages ago, when I was a kid, and it was only a brief mention. In brief, it talked about dealing with the problem of space junk by requiring any orbiter to deploy a large gel disc, spin-stabilised, near the ship. The idea was that any junk or debris that was jettisoned by the ship would be trapped in the gel instead of flying off who-knows-where. This isn't perfect, of course, since it only protects against debris in a narrow band, but you could add a couple of discs around the structure. ## 3) Make your ship out of non-shatter materials This is kind of a sub-set of 1), but distinct enough for its own page. Different materials react to explosions in different ways. By building your ship from something that does not break up into fragments in a blast - largely plastics - or coating them in such materials - like, say, [Line X](http://www.linex.com/) - you can ensure that while the contents of the station may be destroyed, the debris is manageable. [Answer] First references. Relevant papers include [Kessler and Anz-Meador, 2001](http://adsabs.harvard.edu/full/2001ESASP.473..265K) and [Kessler, et al, 2010](http://webpages.charter.net/dkessler/files/Kessler%20Syndrome-AAS%20Paper.pdf). Where have I heard of this Kessler guy before... # Strictly limit the number of objects in orbit This is a 'first principle' to be used in conjunction with one of the other two below methods. If there are 100 space stations in similar orbits around the earth, then, everything else in a nearby orbit down mm size needs to be removed. This can be done with laser ablating, or by having 'space-tugs' go 'trawling' with large nets or whatever. If an investment in near-zero space debris is made, the sudden catastrophic loss of one station is much less likely to cause a cascading failure. The number of particles caused by the breakup is relevant. Per the 2001 paper, a 1985 Air Force anti-satellite kinetic kill experiment hit a 850 kg satellite with a 16 kg projectile at 7 km/s and generated 285 catalogued particles. Per the 2010 paper, collisions can be divided into two types, non-catastrphic and catastrophic. A non-catastrophic collision (small particle, large space station) will generate about 100 times in mass of debris as the mass of the impacting projectile. However, most of these particles are too small to catalogue and would not contribute to cascading. A catastrophic collision would involve a full breakup, and result in 90-100 particles that are themselves large enough to cause cascading effects in other satellites of the same size. For example, the 1985 Air Force test yielded between 80 and 95 particles that could have catastrophically destroyed other 850 kg satellites. So if there are 100 orbiting space stations, and strictly nothing else above 1 cm, then even a catastrophic explosion will only result in about 200 orbiting objects that could cause further cascading collisions. Since that is less than the number of active satellites right now, cascading failures could be unlikely. # Orbit your space stations very low so atmosphere removes much debris Place the space stations in a very low earth orbit, at 200 km or even lower, at an altitude where the stations have to use thrusters periodically to counteract atmospheric drag. Then, a catastrophic breakup will send half of the objects hurtling into the atmosphere, preventing them from being a problem. Fig 1 of the 2001 paper shows the altitude distribution of debris from the 1985 Air Force experiment. The satellite was killed at 525 km, and the debris is in a bell shaped curve from ~400-700 km. If a space station had been killed at 200 km, then it is feasible that half or more of the fragments would be pushed right into the atmosphere and not be available to impact other stations. # Orbit your space stations in medium earth orbit so there is much lower chance of collision. This is just simple geometry; the surface area of a sphere. The volume of a 10km deep shell around the earth at 500km orbit is 5.9E9 km$^3$. The volume of a 10km deep shell around the earth at 5000km orbit is 1.8E10 km$^3$. If the low earth orbit option reduces amount of debris released by a factor of two, then the medium earth orbit option reduces the particle density and thus the probability of being hit by a factor of 3. Also, in the 2010 paper Figure 5, the authors use model results from [Liao and Johnson, 2006](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.474.4393&rep=rep1&type=pdf) to predict instability of debris fields by altitude. They conclude that the region between 600km and 1700km are unstable, with specific bands within it at increased risk of 'runaway' cascading Kessler syndrome effects. So by going low or high, we can void this dangerous region altogether to increase the chances of survival. [Answer] With the numbers you called, there would probably be no exaggerated risk of Kessler Syndrome. According to the [Wiki: Space Debris](https://en.wikipedia.org/wiki/Space_debris) there are already a few thousand *metric tons* of debris in NEO. Your hundred 10x ISS sized stations would have an approximate mass of 400.000 tons. Assuming tracking technology is at least as good as it is today, each piece bigger than ~1cm can be tracked and simply be avoided. Its what the ISS already *does today*. In case terrorists or accident would blow up a station, this would add *about as much* debris as there already is today. Also, retention times in lower orbits range from a few years to a few decades before stuff deorbits on its own by atmospheric friction. Large pieces could also be brought down by automated probes that attach to the piece and then deorbit actively. By design, stations could also be built to *not* break into too many pieces, making the debris pieces fewer and easier to remove. Equipment can be hardened against very small pieces (dust). To actually cause a runaway kessler syndrome it would only suffice for terrorists to blow up a station if nobody acts to prevent the consequences. While the debris from one or two stations *might* be enough to cause kessler syndrome in the long term, as outline above there are ways to remove debris *before* it escalates. Thats especially a factor if you assume access to space is *cheaper* than it is today and technology ~~two decades~~ 120 years advanced, making space technology cheaper as well. [Answer] You could have a fleet of small drones with efficient ion or em propulsion whose job is to attach to any dangerous debris and fire their engines enough to de-orbit the debris. Whether the drone goes with it or fires its engine to regain orbit is up to you. A kessler syndrome does not mean immediate destruction of everything. If a space station explodes, it will send out a cloud of debris, but this debris is unlikely to intersect anything else for thousands and thousands of orbits. Eventually some bit of debris hits another station and the situation worsens, but it's still not a terribly rapid process. Space is BIG and still mostly empty. Wikipedia page on space debris says that satellite lifetimes in a kessler syndrome would be reduced to years, or months. I think this is reasonable reaction time to be able to identify and track debris, launch interceptors and perform debris avoidance manouvers where necessary. Yes, it requires preplanning and thought, but the OP is looking for preventative measures, and stopping the cascade in the early stages is very important. [Answer] Putting 100 space stations into orbit is no small matter, and would be very taxing (titter) for the people of Earth so I assume you've employed nano-bots for construction, with towed-in asteroids for raw materials... or something similar to that? If so, why not build all the solid bits (external skin, superstructure, internal elements) with fused molecular-scale nano-bots? They would lock together and achieve their rigidity by means of phased power transmission running through the structure. Should any part of the structure be separated from the rest, there would be no active signal to keep the bots together, and they would drift apart, breaking down in the cold of space into individual silicon atoms. Non-fixed parts (eg tools, etc) can also be constructed of nano-bots, but fused by means of a gel-based power pack that maintains a wireless link to the station (or portable source). Should the object move out of a threshold range, it, along with its silicon-based circuits, would drift apart into silicon atoms. The exposed power gel would become brittle, breaking down into microparticles in the cold of space. This opens up some comedic possibilities here, where a crew member might go EVA for maintenance, but forgets to "pair" his tools with his suit... you can picture the expression on his face as his drill dissolves away to dust in his hands. Soft furnishings are not likely to become dangerous debris, but could still be woven partially from nano-fibres that break their bonds at low temperatures. Unfortunately, food, water stores, waste, and human/animal bodies are another matter. They would quickly freeze into large, dangerous projectiles. For any stores (food, water, waste) one possibility is to build all containers out of matter-eating nano-bots. They form a rigid container, remaining quiescent on the station, but away from it in space they would devour all contained matter, excreting a dust of component atoms outside the container. When there is nothing more inside the container, the nano-bots dissolve away into atoms. Don't put your school lunch in 'em. For bodies... well I'm stumped with that one. I cannot think of any nano-tech solution that isn't also the grisly flesh-eating basis of yet another Michael Crichton novel. Note: power and transmission sources would have to be well shielded of course, to prevent space pirates (or demented hobbyists) from firing off EMP blasts and watching space stations dissolve away to nothing. [Answer] Earth will have a rapid detection, rapid reaction, automated system set up. Within minutes of a station blowing up (maybe even seconds), dozens to hundreds of old-fashioned chemical rockets will be launched with custom payloads on freshly calculated trajectories, to intercept and deorbit all large debris in a matter of minutes, not hours. If that sounded far-fetched, think about the scores of InterContinental Ballistic Missiles (ICBMs) that the US and Russia keep pointed at each other, ready to fire at a moment's notice. That's a few decades old already. What I'm proposing is strictly harder, but a reasonable extrapolation. Instant detection and tracking is the only technology that needs large advancement to make that feasible. [Answer] Are you running fusion reactor engines? They’d have a rather large and hot tail. You could have cleanup drones with a big wide radiating exhaust. They speed up and slow down in the orbit of that mess. Burn it all to component atoms in a fusion torch. A number of those would be in standard orbit awaiting automated activation upon detection or on the basis of based instructions. Drones would have to dock with your stations semi frequently to refuel. You could have it a requirement to have an X number of them to have a stable orbit assigned to you for a permanent orbiting station. ]
[Question] [ **A Little Background** March came and went, but the snow continues to fall on earth, even in Sudan and Brazil. What was once thought of as a miracle of Christmas has begun to cause problems. Winter came and with no signs of the coming spring, this is a problem. People are beginning to panic, what was once a world wide Christmas miracle has become an icy hell, but they are not mass rioting for answers yet. Most people are looking to their government for answers, but they know nothing, and even if they do, no one is talking.In the foreseeable future, the winter would not end. Farmers have no way of growing crops and they are resorting to culling farm animals. Most of the world's freshwater lakes have frozen, crops can no longer be grown, etc. For all intents and purposes, this is a new ice age. **The Question** I could go on, but the the premise is simple, as are the small effects caused by it, but I'm curious about global survival. I have asked about [the social effects of such an ice age](https://worldbuilding.stackexchange.com/questions/33345/the-neverending-winter), but now I am asking about survival. What can people do to survive? What can the government do? It goes without saying that unless the world can work together for this common goal, humanity is doomed. How it happened is irrelevant. If it was caused by mankind, it isn't something they can just undo. But it just as easily may have happened somewhere across the galaxy and there is no way for humanity to stop it. How can humanity survive this New Age of snow and ice? [Answer] First off, I expect that governments will not play a large part in this. A global event like this has unimaginably large consequences, and I don't think there's ever been a large government in the history of mankind which has the agility to deal with this. There will be death. There will be rioting. There will be a breakdown of society. That is a reality to face. But that's not the certain end of humanity. Humans are marvelously resilient creatures. Some will band together and begin to survive. Most likely they will be groups under 150 people, which is [Dunbar's Number](https://en.wikipedia.org/wiki/Dunbar%27s_number), and they will each come up with their own solution to survival. Eventually those who survive may begin to merge back together and start forming what you and I would call civilization, but that's the easy part. The hard part is getting there. We won't be able to bulldoze our way through this, like we love to in so many crises. There is not one solution which we can list which saves humanity. We're going to need to do what other animals do: listen and find our place in the planetary web. What we do to survive depends *highly* on what other animals do, because we're going to have to coexist with them... and likely eat them. (which is sort of coexistence... in a Hanibal Lecter sort of way) The oceanic food chains are going to be our best bet. The sudden freezing of the world will raise hell on terrestrial ecosystems, but the ocean's raw body of water will serve as a temperature buffer giving more time to adapt. I'm not talking about Darwinian evolution here, because this will happen far too fast for that, but the different balances of species will have to adapt to the new climates. The food chain found in [Antarctica](http://www.coolantarctica.com/Antarctica%20fact%20file/wildlife/whales/food-web.php) provides some hints as to how we might survive. Baleen whales, gargantuan graceful creatures, survive these extreme environments by eating low on the food chain. It is reasonable to surmise that the sort of plankton and krill which form the basis of the Antarctic food chain might spread north, so we may be able to leverage that food source. It's also possible that the Arctic food chain from up north progresses downward (giving us a chance at land-walking meat). I would expect that the native people of these extreme regions, such as the Eskimo and Inuit, will have little trouble. Maybe we'll be willing to learn from them, and maybe they'll be willing to share their way of life. [Answer] If you want to know what happens, when it's suddenly cold and you are not prepared, read about [Sybiraks](https://en.wikipedia.org/wiki/Sybirak) - Polish people sent to Siberia by Russians. In your situation, a whole planet faces what they did, except for Russian guards, of course. Key points are: 1. Lack of proper shelters and clothing kills fast 2. Proper shelters and lack of proper clothing means you have to improvise, or people start to starve in barracks. 3. Fuel is life. Be it wood, charcoal, oil. Whatever keeps you warm and allows to melt snow for drinking. 4. Surprisingly many organisms can survive winter like that. Permafrost regions still have woods, grass and so on. As long as there is enough sun, you can have valid ecosystem. The death toll among Poles was great, but they learned from natives. Surprisingly, if documents are right, [only about 5 ~ 6% of those who arrived, died](http://www.poranny.pl/obserwator/art/5285416,70-lat-temu-rozpoczela-sie-masowa-wywozka-polakow-na-syberie-deportacje-byly-zemsta-stalina,id,t.html). And they started without clothing and with bad shelters. Of course, they had an ecosystem suited for something really close to perpetual winter, and natives to learn from. And, of course, oldest and weakest probably died before. But still, whilst it was hell, it was surprisingly survivable. [Answer] There are a few forks. In the short term, some humans may adopt a sea-based hunter-gatherer survival strategy. Existing expertise with fishing is key here. The oceans have a lot of thermal mass, so they will take a longer time to freeze over. Another short term strategy involves greenhouses and copious use of energy. Geothermal power will function (until things break down), and nuclear power with its insane energy density could hold up pieces of civilization. The hard part is maintaining the supply chains to keep everything working under catastrophy and chaos. As time progresses, things get worse. A winter is different than an ice age. In a winter, the snow melts eventually. You can just push the snow aside, or gather it in an out of the way place, and wait. In an ice age, there isn't enough space to push the snow aside. It continues to build up. Glanciers form, and the ice becomes geological. The ground, which contains minerals and organics, becomes buried and out of reach to surface organisms. Deposited organics gets buried under yet another and another layer of snow and ice, and becomes lost to the surface biosphere until melting occurs. Even a sea-faring people need new materials, and even northern hunter-gatherers live on the land and get resources from it. So the sea-faring hunter-gatherers will be frozen out by the glaciers. The nuclear and geothermal bases can continue a war of melting. If a good chunk of a continent can be covered in such nuclear/geological powered colonies the glaciers could be held back. But as ice flows towards gaps, you basically need to melt an entire continents worth of precipitation. [Total world rainfall](http://hypertextbook.com/facts/2008/VernonWu.shtml) is 5E14 tonnes. Melting water is about 300J/g. So to melt the world precipitation requires 5E15 watts of power. This is a K type 0.9 civilization, beyond our current budget. And way larger than what can be produced by geothermal (5E13) even theoretically. The thing that can save us is that precipitation has to come from somewhere, which requires sublimation or evaporation. As the world freezes over, less and less water vapor will escape into the air. Clouds will die out. Solar power will become more practical. The source of the ice age now matters. With clouds discounted, the sun's radiation will beam down on the Earth. The white earth will reflect more light, and together with if the sun's output is reduced it could explain a continued ice age. Use of solar power at this point could help with pushing back the glaciers. But turning solar power into electricity, then melting ice, is less efficient than just heating up the ice directly. Put coal dust on the glancier tops and let the sun heat them up. In the long term, things get worse. The oceans surface can freeze up, followed by deeper portions. Vents at the bottom of the sea remain melted, with liquid water volcanoes sometimes reaching the surface. All other life is gone (except possibly human nuclear/geothermal bases). Some think this may have happened in the past. The natural way to get out of it is to wait for vocanoes to emit large amounts of greenhouse gases, like CO2. With everything covered in snow and ice, weathering (which naturally removes CO2) and plants (rare, which consume it from the air) are missing. So the CO2 levels in the atmosphere build up to seriously large levels and the greenhouse effect kicks in. Things warm up, glaciers melt, albedo of of the Earth drops, things warm up more. If albedo drop outpaces weathering+live, the world continues to warm up. Eventually weathering+life+radiation start slowing greenhouse faster than albedo increases help it, and the world stabalizes with a melted ocean. So a long-term defence would consist of finding artificial greenhouse gasses and terraforming Earth. In the epoch term, whatever led to the cooling of the Earth may not be satisfied by simply painting it black. If the sun is dropping to 50% of its current brightness somehow, no amount of coal dust or greenhouse gases will prevent an iceball Earth. Humanity would have to climb up to a K1+ civlization and stop being planet bound to survive, all while trying to live through a catastrophe. Desperate measures and technological revolutions would be required. Human extinction is by far the most likely result. --- In the short term, non-industrial civilization could survive, but in the medium to long term only an massive industralized response to this crisis could surive. Things would be very precarious as a breakdown in any supply chain could wipe out all of humanity, and supply chains would be extremely hard to maintain over the frozen Earth. It would take civilization-scale effort to rescue the human race from a rapid, total and unending ice age. The odds are we wouldn't survive, and at the least the vast vast majority of humanity would die. If we did survive, the civilization that emerged would be as different from today as modern industrial civilization is from ancient Egypt. [Answer] First concern: societal reaction. Food would run out fast. With crops dead everywhere but in greenhouses designed to withstand winters, food supplies would be severely limited. Riots, suicide, end-of-times predictions, etc. would cause populations to dip significantly. This would be felt the most in large population centers. Governments would topple, sometimes overnight, gangs would form, and chaos would reign for at least a couple of months. Disaster at a global scale is something humanity hasn't faced in recorded history, and even on localized scales, governments have a hard time keeping power because when people are dying, they begin to see that the government is, ultimately, irrelevant. Second concern: Long term survival. Greenhouses would become commonplace overnight, with insulation, underground farming, etc. Anyone with access to such facilities would either be giving out those goods out of the goodness of their hearts or, much more likely, using that access to gain social goods that simply aren't available to anyone else. Eventually, those in power would accuse these farmers of selfishness and a complete lack of empathy in order to take over their facilities and place them into government control. Efficiency would fall as a result, which would wind up causing even more of the public to die off. I see reliance on the ocean as a possible way out, but I also see a lack of effort in that direction simply because the infrastructure for supporting human life underwater is extremely limited (read: nonexistent) and would take years to develop. With a good chunk of the world's population on the brink of death, we don't have years to get our act together and engineering solutions on land is far easier. In the end, humanity would prevail, but at the cost of a large portion of planetary populations and the loss of much infrastructure and social order. When the dust finally settles, new people would be in power (for better or for worse), new monetary mechanisms would be in place, and only a few population centers would remain. Flash-frozen jungles, meadows, mountains, rivers, lakes, etc. would cover the planet, perfectly preserving a record of what once was. Once motivated in this way, I imagine the technology developed to continue to survive on Earth would be equally applicable to survival on the moon or on Mars, so people would begin to look skyward for an escape from a planet that has, ultimately, become hostile to human life. [Answer] That mostly depends on how cold it will get and how fast. If there is time to prepare, let say a gradual decline in the temperature over a decade, many technological societies will have time to prepare. To a genuine effort to be made, something clear must point to a long winter. Something like a measurable decline in solar output or a measurable change in Earths orbit. Actually is not a far-off idea. There is an hypotesis that a scenario like that happened a few times in the history of Earth. Not in a single winter, of course, but in a few times Earth was covered on ice even in the equator. In a scenario such as this, most human population will die, no doubt about that. In a colder environment there is no way to produce enough food. Fossil fuels, volcanoes, nuclear power and wind will allow pockets of technological population to be warmed. Indoors farms will be able to sustain decent colonies. That in the equatorial regions, of course. Even if governments can't prepare, which is probable, many scientists, engineers and inventors can develop the necessary technologies to kickstart the winter civilization. Resources will be plentiful for those that survive. An oil wheel will last almost forever for a small community. Supermarket and factories of canned food will last for years. Dead frozen animals will be mined for quite some time. Engineering components will be harvested from cars, computers and buildings. This new technologies will have to shift the concept of our society. We develop components and mine raw materials all over the world. The engineers will have to do with local goods. That means, nuclear power plants will run for some years and then be replaced by wind turbines and fossil-fuels that are easier to make and depends on widelly available resources. And construction will change. Machines that work in normal temperatures does not work in the very cold. The Challenger explosion is an example of a machine designed to the summer launched in the winter. Of course a percentage of the population will survive as hunter-gatherers like the Inuits. And they will move to everywhere in the world. With the seas frozen all surface can be walked on. If gets even colder than our poles are today, People will have to live underground. Maybe even in stations isolated from the environment. [Answer] I have an idea for a novel about this topic. In my novel, the sun began to weaken. (Try not to think too much on that) A new ice age has begun. In my novel, scientist throughout the world have predicted this event and are working with the government to prevent the extinction of mankind. They began huge projects to build enormous buildings powered by geothermal energy. To do this, each building would have a it's own drilling sector and they would drill straight to the Earth's mantle to collect the magma. Each of the buildings have large subterranean power plants to process the energy. The building have sections for everything we need to survive. Lower levels for agriculture and mining(maybe), there will be civilian levels, manufacturing sections, etc. These buildings will be build almost everywhere for humanity to survive. All that's left in the formula is generous governments........... [Answer] If it suddenly turned out that it was going to be winter all the time, I'd immediately think about greenhouses. [This link](http://www.treehugger.com/lawn-garden/how-to-build-unheated-greenhouses-for-winter-harvest-organic-gardening-eliot-coleman.html) describes a method by which a greenhouse that operates during all four seasons can be constructed. If you had trouble keeping the greenhouse warm, then you could use solar panels (or traditional oil/gas/coal) for heating. So *my* answer to the question "how long can humanity survive" would be "**indefinitely**". I think an appropriate adaptation of the question could be "how much would the carrying capacity of the Earth be reduced?" (a lot). That would depend on the exact circumstances of your eternal winter. [Answer] In my opinion the greatest risk for humanity would be the onset of such a catastrophe. Realistically it would not be over night but rather decades till earth freezes but one of the first reactions should be war for resources. And it would be an all out war as the loser would surely die so mutually assured destruction is on the table. It could easily turn out the end for humanity. Also it will use a lot of the remaining resources. Next would be the strife for technology to deal with the situation. In almost any scenarios it should be possible to find technologies to deal with new circumstances. May it be using geothermal energy, nuclear or even (less efficient) solar power. They might be even able to settle on another planet. The question is - will a group be able to develop and deploy such a technology before it's resources are used up and they starve or freeze. Once just one group manages these two steps humanity should be safe despite living in permanent winter. [Answer] Extinction isn't really a probability in this scenario--Most of the people on the planet will certainly die, but not all. Animals and People survived pretty much continual winter without our current level of technology. Today various small groups could easily survive by living and growing crops underground--my guess is there are probably already hundreds of places on the planet set up to do this. Fuel will be a little tougher--but not that much. As long as you have food, machines and fuel you can run an oil rig. You won't need anywhere near as much fuel because nearly everyone will be dead--a single oil well could supply all of humanity. Solar will be fairly useless, but wind will probably still work with some redesign and who knows, someone may invent a new "snow-driven" renewable power system. I guess as long as we have shelter, power and enough clear, warm, illuminated space to grow crops--we'll survive. We'd make it for quite a while without power too-but it'd be a lot harder. If you want to save, say 1-5% of the human race however it might not be possible. [Answer] Electricity can still be generated (in the same ways we generate it today). Thus, large indoor areas with heating can be maintained, allowing for shelter and crop growth. We can also eat (and grow) seaweed. [Answer] OK, unless the world keeps freezing to the point that it reaches the [Snowball Earth effect](https://en.wikipedia.org/wiki/Snowball_Earth), people from any industrialized society, knowing what's coming, will move to the relatively warmer climate areas at the equators, where winter will not be so destructive. Those who can will build and expand small cities around geothermal hotspots. In Iceland, around Yellowstone, by Etna in Sicily or by the Campi Flegrei in the Gulf of Naples...everywhere there is enough natural heat the industries will do their damnedest to pump up all the energy they can to warm up water, people and grow food in hydroponic greenhouses. Genetic scientists will work with one purpose only: create crops with the maximum yield possible. ironically, only by burning oil and carbon as there was no tomorrow would help heating up the atmosphere, but this glaciation would cripple the industries. And the armies of all surviving countries would have to shoot people to prevent burning what's left of the trees for domestic purposes. If all trees die, it would be an even more dire event in this chain of destruction. It may also sound macabre, but corpses under ice will give the survivor much needed food. Just like it happened in the harsh winters during Stalingrad's siege. The sea will be another precious, the only source of live food. Pirate wars will be fought for the conquest of the seas and their trove. But even in this horrible, global chaotic situation, humankind can live, make through it as The Long Winter recedes decade after decade. ]
[Question] [ Humans don't exist, at least... not here. Instead we have [Insert non-lame animal name here:]. They're not too bright, but also could be considered vaguely self aware, about Gorilla level intelligence. They're roughly bipedal, but can get quite a trot going on all fours. They're thick skinned and durable, and can withstand blunt-force impact similar to being hit by a truck. They're furry tanks, basically. Obviously such a predator would be hard, if not impossible, to kill without an overwhelming numbers advantage and would most likely be the dominant species on the planet (as well as an absolute monster of an apex predator)... but with no threats to their position in the food chain, would they develop into what could be considered an advanced civilisation? Would there be any reason to develop tools, invent things, if there was no survival requirement involved? Or would they stagnate and remain ape-like forever, like politicians? **Edit** Forgetting the Gorilla comparison, the question I'm asking is whether an intelligent, tool using, engine building, airplane flying civilisation could develop from a species that had few, if any, external threats? Assuming that humans developed the way you did in order to improve survival chances in a world where we weren't the toughest kid in school, would the toughest kid in school bother to develop in a similar way? [Answer] **TL;DR - absolutely. Evolution doesn't stop just because you're good at something.** Stop for a moment, and imagine a member of your species who is a perfect physical specimen, for whatever your selection criteria are for 'perfect'. Now imagine that you absolutely cannot bring yourself to engage in conversation with this person for more than five minutes at a time. Selection pressures have guided you into a position where this 'perfect' thing was overrated, and you will reevaluate your position on the definition of 'perfect'. Similarly, the not-a-gorilla apex predator will make selections when mating, and given enough time, social dynamics come into play. Maybe it's like a lion's pride, and the strongest male gets all the dates. Maybe the female is the stronger of the species, and devours the male after conception. But one day, a not-a-gorilla is born who is different. Maybe he's just a LITTLE smarter. But he figures out that the females like gifts of flowers, or tasty critters to eat. He brings the tasty critters, doesn't get eaten and now he's very much more likely to survive to make more progeny than the ones that get eaten. And it doesn't have to be social dynamics. The point is that there are SO MANY pressures causing evolution, that simply being on the top of the food chain isn't enough to stop that, especially over the long term. The point of my earlier comments on your post is that, after enough evolution happened to create advanced intelligence, the new not-a-gorilla is probably nothing like the old not-a-gorilla, in the same way that I'm only a very tiny little bit like an actual gorilla. Minor Edit: I feel compelled to point out that when the not-a-gorilla has developed intelligence, I am in no way implying that it will be smaller, weaker, slower or mostly bald. We only turned out that way mostly by chance and choice. At some point, less fur became attractive. The advanced not-a-gorillas could have gotten bigger, faster, stronger, hairier, and more durable in the same time frame that they became intelligent. Evolution doesn't have an end game, it just comes down to who makes more and better babies. [Answer] One theory of human brain development is based on [Social Intelligence](https://en.wikipedia.org/wiki/Social_intelligence#Hypothesis). As humans began living in larger social groups (tribes and clans) our brains doubled in size to track these complex relationships. My sister's husband is off limits, but I can date my sister's husband's brother. My father's enemy's son is my enemy.... We have complex social rules which are fundamental to us, but really have no purpose in nature so it wouldn't evolve directly. Instead, as the theory goes, we needed to keep track of who was who in the "in circle" around the various alpha positions and their families in society. If your family is close to the king this actually does impact your genetics, over and over in numerous ways. Children of the king's friends get married and you have an aristocracy – tracking a royal heir can sometimes be a societal obsession, and even in social animals [the children of alpha females are treated better](https://en.wikipedia.org/wiki/Spotted_hyena#Social_behaviour) because of nepotism (nepotism literally means "nephew-ism"). Scheming men and women breed with the powerful, and they have powerful scheming children. This consolidates to an evolution of social intelligence that has nothing to do with mechanical engineering or scientific observation. It might however be related to language skills, persuasiveness, charisma. It also might explain cult leaders and narcissists who exploit a kind of social control over people even when it seems to defy logic. How much of today's telecommunications and broadcast media is simply about the relationships of status individuals in society? So if your critters have a strict social pecking order with lots of complicated rules they are expected to follow, they could be a society of backstabbing power-climbing schemers who are savvy and manipulative without necessarily being *hammer and screwdriver* intelligent. [Answer] I think it's entirely possible... Once a creature is at the peak of the food chain its only competitors are its fellows. As in your creature could evolve to be intelligent simply by competing with others of its own species for mates and resources. Given a significant population this sort of competition becomes inevitable. [Answer] The problem an Apex Predator has is having enough prey, and reducing energy expenditure to catch said prey so you come out ahead. Once that is solved, the next problem is socialization. There is reason to believe that humanity's intelligence developed to deal with other humans; we build complex social models to win the "in-tribe" dominance games and have more kids than the other humans. So one issue is that your Apex Predator doesn't have much need to be social; in fact, a large group of such Apex Predators would starve as they consumed all the prey in an area. Trying to scale up the prey as well runs into problems, as your size gets larger your N gets smaller, and smaller N leads to more instability. However, what if we presume our Apex Predator forms a symbiotic relationship with a prey species; the Apex Predator becomes a herding species. They herd one kind of herbivore, which they use only when short other food, while they hunt other food. Clashes between herders require their impressive size and strength, as does hunting other species. Herding requires more than one of them, providing socialization and a red queen's race of intelligence within the social groups. The herd animals being larger than them would also provide a reason for them to be strong. They would cull the most aggressive, but they would still have to deal with brontosaurus sized cows. Similar symbiosis occurs in nature without intelligence. So it isn't completely ridiculous that it would precede the development of intelligence, then lead to more developing. [Answer] I think that it isn't likely. Intelligence is a big investment. The young develop slower since you have to teach them. You have to grow a bigger brain that consumes a lot of energy. Luckily meat is energy dense compared to plant matter but there is still the question: why did the species bother? Intelligence develops to solve problems. So, you have to figure out what problem arose that intelligence was needed to solve? One possibility is that intelligence led the creature to become the apex predator. By using their intelligence they removed their rivals (like with us). However, if the predator had more going for it (speed, claws, poison, armor, etc.) then once it was smart enough to remove the threat, it wouldn't need to get any smarter. [Answer] Sure, evolution was spurred by natural bottlenecks like droughts, ice ages, isolation etc,. more than competition with other predators. Make one ice age 1 degree colder or hotter and it would have turned out vastly different. Humans would be physically, mentally, and socially widely divergent from what we are now if we survived at all. Other species were at comparable levels many times in our prehistory. So complex civilisation for your unnamed predator could have been a result of needing to cooperate and develop social systems as a means of survival against a series of natural events rather than competition against other animals. [Answer] The trouble apex predators have re: continued evolution isn't that they have no predators etc, it's that they can go anywhere they want to. When a mutation occurs it's chances of recurring sufficient to become an emergent property of a species are massively diminished in a large genepool. This, not any other factor, is the primary reason why Apex anything don't tend to evolve much. Humans have bred plants and animals by doing what nature does..inbreeding. Yes, that's right.. you wouldn't be as smart as you are if it wasn't for inbreeding. Isolation begets evolution. With this in mind, Apex (walking, hopping or slithering) predators can reasonably be expected to evolve 'further' if some event isolates a breeding population from the greater whole. In fish, & birds this is clearly harder to achieve, given that natural events that can dislocate one breeding population from another are...well, they don't really happen very often at all. Some species have essentially locked themselves into their path by various forms of ingrained migration tactics, which whilst helping the species survive in many senses, essentially drop it from the list of "species that might go somewhere" [Answer] There would be no reason for them to evolve if they don't compete amongst themselves or have some external forces working against them, because they're dominant. Look at some animals that have stayed pretty much the same for millions of years because they reached a kind've happy medium. [Answer] Why not look to the oceans of Earth? **Orca/ Killer Whales** are Apex Predators and have been for quite some period of time. They have social behaviour and work together to form complex hunting techniques to take down most other creatures around. However, they do not appear to have developed the ability to create supermarines (reverse submarines) to conquer land, nor the need to use tools, create industry, engineer items, etc - all things that we deem necessary as an advanced civilization - even if the development of nets would aid them capturing prey, housing could provide shelter for their young, glass-walled air-tanks to keep naked chimps in as pets... [Answer] **One critical factor is missing - tool using.** As has been pointed out social predators like orca and to a lesser extent lions and wolves by default have more or less complex means of communication. None of them however develop tool using abilities of any significant because they are not equipped by evolution to do so. Your gorilla like predators have mass and speed and use them to hunt effectively. They don't *need* tools to extract resources from their environment. Our ancestors weren't equipped by nature with fangs, claws or speed. But by the time of the arrival of Homo Sapiens our ancestors had *become* apex predators - they just didn't start out as one. They had to learn how to become the most feared killers on the planet. Your creatures don't have that problem, they are already top of the heap. They may be intelligent, self aware and communicative but they will never build a city. What environmental pressure is there to force them to become tool using? The only possibility is larger/more dangerous foes and perhaps a changing environment where the 'old' way of obtaining calories was no longer as effective as it used to be? (I.E. the same things that forced our early ancestors out of the forests and onto the savannas. [Answer] The evolutionary pressures on your apex predator are internal to their species. There are two ways that one predator can out-compete another using intelligence. 1. Social. A predator can make better alliances, bring down foes, scheme better. 2. Tools. A smaller, weaker predator can use tools to compensate for being weak. It may even use tools to get food that the larger, stronger predators can't get. Such as learning to paddle a piece of driftwood to get out to the island where the other ones can't hunt. ]
[Question] [ Several times I had idea for a medieval-like world where the people living on the planet did not discover all the world yet. I know the first two steps: 1. Create a map of whole world, for worldbuilder's own purposes 2. Create a map with white spaces (here be the dragons) from point of view of the people living on the world Although the step 2 sounds easy, It always gave me headaches in where *exactly* should the line of *Terra Incognita* go. So I would like to get some answers: 1. How far from a village should I plot the "we do not know what is there" line? (again, reminder: Classic medieval world with no magic involved, fastest means of transportation is a horse) 2. Should I use geographical landmarks as "border of unknown"? E.g.: No one crossed that big river yet, so behind the river are woods and dragons live there 3. And ultimately: What are common reasons to stop discovering? Why would medieval person stop at a river/mountain and not go any further? **Edit**: My basic intention is to let the reader look through eyes of the medieval person (so the reader will know only second map, with white spaces). The only person "to know it all" is the worldbuilder, alas me [Answer] I think your headaches come from misunderstanding why the blank spaces exist. The Terra Incognita is simply an area **the cartographer** has no good information on. Most such areas had people living on them and trading with their neighbours. The Americas had advanced civilizations and were presumably visited by several groups before Columbus, but that didn't really help cartographers that much. Phoenicians presumably circumnavigated Africa. Neolithic trade networks were very extensive. Romans had contact with the Chinese long before Marco Polo. The borders of the Empires were briefly close enough that a war was a theoretical possibility. The point being that Terra Incognita do not arise from lands being unvisited, they arise from the information being unknown to the cartographer. Just like the name says. It is important to note that what is unknown to one cartographer can be well known to another as long as the first cartographer has no access to the maps made by the second. And that if a map says a country has people with dog faces or bat wings that gets copied just as well as any other data. Most maps were based on second hand information and had reliability to match. So what you need to do is understand the **flows of information**. Start with primary sources. Nomads, hunters, fishermen and few other professions can range over large areas. Unfortunately these groups tend to be insular and especially suspicious of strangers asking questions about their pastures, water holes, fishing or hunting grounds. They'll pass on rumours of people they come into contact into and can guide travellers passing thru, but they are not very good sources for maps. Traders follow those rumours and constantly look for new trade routes. They'll travel far if they are following something valuable, like silk, porcelain or tea. Gold, silver, and precious stones are also good attractors. Unfortunately while traders are good with dealing with strangers, even curious ones, they are competitive. They will not divulge valuable information about their trade routes where a competitor could hear it. So unless a far travelling trader gets somehow stuck with a lots of time where he can't actually use the information himself, say a prison, he is not going to be a good source for cartographers. Official follow armies or conduct diplomatic missions to foreign realms. They generally make good observations as it is usually part of their job. Unfortunately their social status generally makes them unavailable to cartographers. And their actual reports are limited to other government officials. So it is basically up to their individual literary ambition. And even when they write they are usually more interested in the people than geography. So not very good source for maps either. Pilgrims and missionaries also range far and missionaries sometimes intentionally go into the unknown areas to spread the word. Unfortunately if they come back to the known lands where a cartographer can talk to them they generally have a reason for doing so. Their health might be failing with their recollections being vague and fragmentary. They might have come to get funding to their mission, which *colours* their stories. And in all cases they are even more focussed on people over geography than officials are. They probably travelled with a guide who took care of all the navigation and might have totally wrong idea of directions and distances. After that the next issue is with dissemination of information. Accurate maps and navigation data have been considered strategic and restricted information throughout history. Making copies of maps or navigation data was also relatively slow and expensive. These factors limit the availability of mapping information. More importantly for your question it means that information about distant lands will be rare enough that it can be lost. It is entirely possible that the Phoenicians, the Romans, or the Chinese found North America and we just do not know about it. (Although the case for Chinese has become more solid lately?) There might even have been trade for some time without us knowing. I hope this answer that does not actually answer your questions still helps by pointing you in the right direction. That causes less headaches. [Answer] I think **geographical landmarks** make more sense than a simple distance metric. Covering, say, 500 km on horseback, or by horse and wagon, is *very* different if the terrain is wide open plains as opposed to mountainous areas, thick forests, huge swamps, or something similar. This can be amplified by making those areas crawling with animals who will readily attack you, either [rhino](https://en.wikipedia.org/wiki/Rhinoceros)-style plain aggressive, [cobra](https://en.wikipedia.org/wiki/Cobra)-style poisonous, or [tiger](https://en.wikipedia.org/wiki/Tiger)-style outright predation; or mythical creatures like dragons guarding the Great Treasure that nobody knows about because nobody has survived the encounter. Look to Kipling's Jungle Books for an example of this; people living in villages more or less surrounded by jungle, but largely avoiding the jungle for all its dangers. It's easy to **design your world such that there are large mountain ranges, large forests, an ocean, or something else,** forming a formidable (but not impassable) natural border. Particularly in the *absence of a clear incentive to cross it,* in a world that is basically at a subsistence level, that alone will put lots of people off. There simply won't be any benefit that outweighs the difficulty and risk. Sure, life in the village might be harsh, but you have the protection of the village structures, the help of the other people around you, and so on. If you set out into the wide unknown, you risk losing all that. On top of this, you can have whatever leaders have the most clout in your world (whether political, royal or religious) make it very clear that bad things happen to those who seek to cross these boundaries. It works even better if some people tried and didn't return, even if the reason for their non-return in reality is much more mundane. (This gives such leaders obvious examples to point at; the son of the smith of the next village tried to get through the Deep Woods of the East and nobody has heard from or seen him in two years.) Maps are likely to also reflect this in some manner; remember that [medieval maps](https://history.stackexchange.com/questions/tagged/maps) were not the detailed works we think of today, even in their areas where they were filled in. Also, it's worth keeping in mind that different groups of people are likely to have *different* white areas on their maps, simply because their starting points are different. This can lead to interesting encounters for those brave intrepids who *do* venture into the unknown. None of this will stop everyone, obviously, but it can maintain white areas on a map for a long period of time, *especially* in a medieval setting where communications and travel take a long time. [Answer] Try to get inside the mind of a medieval cartographer, and figure out where he would stop looking, and why. Perhaps anyone who traveled past a certain point never returned, as they were eaten by the dragons. Therefore they would not really want to venture into the area of no return. And anyone who had managed to travel there wouldn't have come back with their newly plotted maps. However, the cartographer would try to chart as much land as he possibly could in order to be able to sell his more accurate maps. Therefore, he would likely try to go to as far as he physically could, or to higher ground, so that he could see as far as possible. This would mean that he could at least do an approximate map further than he had actually traveled, but it would generally be less accurate as he has not been able to survey the land up close. If he was able to scale a mountain and see beyond, then there could be some semblance of landmarks such as towns/villages and rivers, as well as the type of land that is there, for a fair distance, but maybe just "penciled in" until it could be verified on any successive trips (the ones from which they would possibly not return). However if there was a hard barrier (such as mountains) that he could not cross, then the map would be plotted up to that point with nothing further. However, if he had gone up to a river without crossing it, he could at least plot that beyond it there was "grassland" or "desert", for as accurately as he could (and maybe even embellish a little, if no one was around to verify it). There was a cartographer who entirely made up the [Mountains of Kong](https://en.wikipedia.org/wiki/Mountains_of_Kong) in Africa, because no one had been there to verify his find for many years afterwards. [Answer] Originally maps were linear in nature, so that along the length it would detail the next place in the journey. Imagine that they followed a series of directions. i.e head from our village to the one just over that hill; then take the road to the big village with the blacksmith (nice picture of a forge); then take the road past the oak tree to a smaller village; now cross the river and head up the mountain road to the village at the head of the valley; that's where we buy our axe, son! By Medieval times they had evolved into what we might think of as a traditional map, but there was no specific way of drawing them, and a lot of them were designed not specifically for navigation. The idea that people would have access to a map to plan a route is unlikely as they were valuable both intrinsically and for the knowledge that they contained. Also the "blank spaces" were filled in with fancy: if you were a Lord commissioning a map, would you be happy with a large parchment that was mainly blank? 1) This means that anything that can't be seen from the route would be Terra incognito (as far as this map is concerned). It also means that even if you had two maps that started and ended in the same place you would be hard pressed to construct an accurate 2D representation of the intermediary villages etc... the type of mapping we think of with triangulation etc... didn't really take place until much later for example the Ordnance Survey of the UK in 1745, and the Cassini maps of France in the 18th Century. I don't imagine that each village would have a map of the locale, which as Worldbuilders we find useful, but would rather have a body of knowledge about the area. 2) Rather than general features you should use impassable terrain as limits, or terrain with no discernible change. people might go to the woods for, well, wood. Or use a river for trade/food. but they might not go all the way through the giant wood, or scale a large mountain range. 3) It depends on your "Medieval" people: if they are subsistence living they won't have time to go further, if they are even able to go at all. Is there enough food supply to keep them going and can they return to tell the tale. If they go somewhere good, why would they return to tell others about it let along map it? If they were an explorer looking for riches you probably wouldn't take a long a lot of expensive and delicate supplies to record your journey. Following the information about your intention it would also be worth bearing in mind that as knowledge about areas was gained there wouldn't be a physical map to update, but rather the knowledge held collectively would be refreshed. This also means that the mental map would have a time element involved, many things far away might have significantly changed, but the message has only just propagated to the village... To help the reader understand you might consider having Elders tell tales, or returning Woodsmen/Hunters explain what they'd seen etc... [Answer] This will depend on who is making the map, and why, in-universe. Maps aren't accurate during most of this time period. Wildly so. Until the Age of Exploration began, accuracy simply wasn't a thing. You've already got some great answers here, going to add my spin on it. Here are some points to consider * Most villages would not bother with a map. Important cities, yes. Tiny towns, not so much. * Many maps were commissioned for important people--Kings, Lords, that sort of thing. They weren't really to help navigate, but for display. To learn what was in the world approximately. * While the map might have everything known on it, it may not be accurate in the least. You ask: > > How far from a village should I plot the "we do not know what is > there" line? (again, reminder: Classic medieval world with no magic > involved, fastest means of transportation is a horse) > > > The answer is **it depends on who is making the map, what they know and what the person that commissioned it is asking for.** Does the Lord want accuracy? A focus on the town? A map of THE KNOWN WORLD? Is this a map specifically sold to pilgrims of the pilgrim route? If so, then mapping the known world would not be the goal. Paper is rare, so they'd have to have some level of education to be allowed to try making it. Most people in England know about London, even if they are far, far away. So let's take that example. If your village is 300 miles away from London, the people there would have still heard of it. Some few people in the village may have even travelled there. So a somewhat educated fellow brought up in the church with a gift for drawing might be commissioned by the local lord. In this case they might detail their own town more than anything, and then set major cities where they know them to be. So York, London, any town above 3,000 they may have heard of, they would place on the map. Of course, **do not assume that the in-universe map is going to be accurate. It's pretty unlikely that it will be.** Your map-maker might know that France is across the channel and where Ireland is, in theory, but it's unlikely that they've actually been. > > Should I use geographical landmarks as "border of unknown"? E.g.: No one crossed that big river yet, so behind the river are woods and dragons live there > > > They would not necessarily place HERE THERE BE DRAGONS on a map like this. It's actually not as common as you might think. Instead, they would just assume land that they know, or vague mountains to fill in the space, placing cities where they believe them to be. (They might know that London is North of York, and that it's on the Thames, but they might not know the accurate shape of the coastline of England). See, your map maker knows that there are places beyond. It's quite possible vaguely know of France, Italy, and Spain. How much they know about the distances between, where they actually are, will be based on descriptions in books they may have read (which will not be all that detailed, or could be interpreted a number of ways). They might not include all these on the map, but could have arrows pointing the way. The dragons and such that you see on some maps actually came later/at the end of Medieval period--and sometimes they were just decorative. Mapmakers would often just talk to people, and they might know someone who knew someone who said there were dragons past the mountains up North. There's no real way to check on it, it's known though, so best put it on the map. Plus it creates visual interest, and mapmakers were as much artists as they were cartographers. > > What are common reasons to stop discovering? Why would medieval person stop at a river/mountain and not go any further? > > > Is there anyone past the mountains that might buy what you're selling before it goes bad? No? Well, it's not worth the journey then. Plenty of Medieval people never travelled more than 30 miles from their home. But there were also folks who made regular trips to large cities for trade and fairs. Also there were religious pilgrims, merchants, and some nobles who just liked to travel. There were also jobs, like fishing, where you could get to know the coast intimately over a wide range. But good luck finding someone who is both educated enough to draw an accurate map and has that knowledge base or is willing to give up the secrets of their trade. Sometimes a lord or king would even ask for someone to travel in order to make a map, if they were interested in exact distances of their kingdom. The question you are asking is so...individual you're asking "why would a person" when people are very different. Why haven't you been to Indonesia? (well, mayhap you have) How do you KNOW it exists for certain? Maps are largely made in this time, based not on personal experience, but on those who came before. **The more detailed and accurate a map is, the more likely it is to be specific to a purpose (navigating the coast, the pilgrim road, a trading route with directions).** [Answer] I'm quite fond of medieval maps and have researched them as a way to see how people think of their world. Most have more in common with a modern subway map. It gives you just the information you need in a graphic format. The border isn't dragons but unnecessary for task at hand. Do people in the European middle ages stop discovering? It segues into the Age of Discovery. :) What keeps people going is money. Trying find more valuable commodities and better ways to get there completely drove discovery. Trade and religious pilgrimages routinely cross mountains and rivers these them the time. I have a couple of friends who just completed a pilgrimage on foot to Santiego de Compestella in Spain. (A popular pilgrim site for a millena.) They have GPS and modern maps but what was very useful on their journey were mile markers, just like the Romans used. There is a concept I've read about in regard to map history, omphalos (latin for belly button). People tend to put what is most important to them in the center of their map. There are many medieval world maps with Jersualem at the center. Growing up the in the US my world map was a Mercator projection with the USA front and center. My mental map of the town I live in has areas of density around the three houses I've lived in with the major connecting roads. [Answer] Most people in a medieval setting travel a day or less from home in their lives, on horseback here's some rough miles per day figures: On Roads / trails: Level or rolling terrain: 40, Hilly terrain: 30, Mountainous terrain: 20. Off-Road (or unkempt trails etc): Level/rolling grasslands: 30, Hilly grasslands: 25, Level/rolling forest/thick scrub: 20, Very hilly forest/thick scrub: 15, Un-blazed Mountain passes: 10, Marshland: 10. Now a mapmaker/explorer (or even just hunters, foresters and other locals who don't work farms) is going to get further off the beaten track or from the river or whatever the main transport routes are in the area than peasant farmers so 20-30 miles is probably a fair point at which to start blurring the reliability of maps (and certainly this is the point at which local farmers' descriptions become unreliable), with MMBA or HBD being everything past the 50, or maybe 100, mile mark from villages and the roads connecting them. That's my thoughts on it anyway, obviously it's going to be much less in harsh trackless terrains (swamps and mountains) or where there are deserts that no-one has ever tried to explore, although the edges of such areas may be well explored and defined. Desert and mountain maps probably have HBD on everything out of sight of the trade roads that pass through. You're likely also to get a Northern or Southern edge where climate becomes a deciding factor in habitation and no-one goes any further because it's just too hard. One other note; there are good socio-geographic reasons for maps to close in as well as the physical geography mentioned above, on a border with unfriendly neighbours there may be a lot of military cartography, or not depending on whether there's active conflict on the border, but civilian mapping is going to be curtailed. Unfriendly neighbours need not be militarily antagonistic they may simply discourage visitors or closely monitor or restrict the movements of foreigners. Information flow across a border may be strictly controlled meaning that one country may have much better maps of their neighbours than any neighbour has of their territory. Where you have differences of habitat, such as forest dwelling Elves sharing a border with farming communities that have little use for the tight growing gnarled old growth trees neither will know terribly much about the layout of each others holdings. ]
[Question] [ We failed to establish communication with the aliens. Our scientists have lost hope in reverse-engineering their technology - what little we can even recognize *as* technology. The only commonality, it seems, is that the biology of their cadavers is remarkably similar to terrestrial life. Close enough to work with. The admiralty has agreed that in light of these circumstances, a policy of artificial genesis is necessary despite ethical objections; the simple fact of the matter is that if we want to avoid or win an interstellar war, we must come to grips with their psychology by any means necessary. The question now stands: how do we do right by these "adopted" children? **Salient Concerns:** * We do not know how social they are. A lack or overabundance of attention at a young age could be psychologically damaging. * We do not know their in-group preference. How many should we produce so that they can see "familiar faces" when each individual is a potential nightmare from an ethical, logistical, and security perspective? * We do not know what we do not know. All of our assumptions are based on terrestrial life and the advice of scientists can only go so far when command itself is untrained in the subject matter. * They will be the first non-human citizens in history. How can we avoid alienating them from society? Both as a matter of formal policy and from the practical standpoint of disclosure to the population at large. * The project may be entirely futile. How do we anticipate the worst without condemning ourselves further? * We are only human. How do we prevent abuse from the personnel entrusted with this mission? **Supplementary Document 1: Our Capabilities & Knowledge** * Our artificial gestation pods are capable of being retrofitted to support embryos produced from some of the undifferentiated cells recovered. * Our techniques for cell cultivation are sufficient to extend this supply of stem cells indefinitely. * Through study of their cadavers and life support systems, we are reasonably certain of their physical needs in terms of atmospheric composition and nutritional requirements. * Our computational capacity provides enough to reason about some of their gross biological process and capabilities, but much of it remains beyond our understanding for the near future. This especially holds true for their brains. [Answer] # Of COURSE we'll screw up royally: There is no way that there won't be massive harm done to these children - at least for the first couple generations. But biology is cruel, ruthless, and selective. After a time, we'll figure out how to deal with them. The process will be ugly, however. Human beings have a long history of learning to deal with non-human children - they're called domesticated animals, or pets. If the process is anything like that, then there will be gruesome mistakes as we poison children, drive them psychotic, create imperfect incubation conditions so they have horrifying developmental problems - and all that is assuming your aliens are derived from a panspermia event, so terrestrial biology is essentially IDENTICAL. Science, done the way it's been done for most of human history, will have a large number of aliens raised like chicks in an incubator. The conditions and inputs - nutritionally, socially, educationally, etc. - will be varied and evaluated. Very large numbers of these aliens will die simply because we don't realize they need large amounts of something basic, like huge doses of lysine. Then there will be screw-ups where they die from terrestrial infections that creep past isolation lines, OR they need symbiotic bacteria we fail to provide. And of course, even if we're wildly successful, the best we can hope for is a bunch of alien children who have been humanized to the point of being unrecognizable, and possibly traumatized by the bizarre upbringing in a giant petri dish. But after a few generations, we will find an accommodation with these beings, dealing with their quirks, exploiting their strengths and weaknesses. If we are extremely sensitive, we may eventually separate them from us and allow them to set up a society to their liking, so they can deal with us on their own terms. More likely, we'll treat them like second or third class citizens because they are unable to conform to our standards. But hopefully we won't make them slaves or pets. **"Hey, Spot, come here! Good boy! Here's a lysine treat!"** [Answer] **This is a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)** *Other than understanding a little bit more about the physiology of the child, you won't learn that much.* In your scenario, you only have two ways to raise the child (we'll leave ethics out of this for a moment). 1. Raise the child as a [feral child](https://en.wikipedia.org/wiki/Feral_child). In this case, the child is raised with no human contact. If... (and that's one whomping big IF), if you can successfully raise the child in a way that the only behavior you see is the "natural" genetic behavior of the "animal" (as in "human animal" if we're talking about feral human children), then you can learn a little bit about the basic motivations and primal behaviors of the species. The reason this is a huge, huge IF is what, for lack of a better term, we'll call the "Heisenberg alien uncertainty principle." Boiled down, you can't measure something without affecting that something. You can't raise the child with robots without that affecting it's behavior. You can't raise it with (proverbially) wolves without that affecting its behavior. **You can't raise the child without affecting its behavior unless, at best, you mimic its original "natural" habitat...** which you said you can't do. Consequently, this path has next to no real value other than to show you the bodily machine in operation, which would help a bit, especially if you want to do things like experiment with ~~biological warfare~~ pharmaceuticals. 2. Raise the child with human help Frankly, from the perspective of trying to better understand the species, this is even worse because the little angel is going to reflect the human behavioral and emotional patterns. The aliens came to us, right? That means they are intelligent, capable of learning... and therefore the cute little munchkin will quickly absorb every human pattern it's exposed to. That will effectively mask each and every behavior you're trying to research with the theoretical condition of *extreme* psychological conditions, which wouldn't exist (IMO) in a successful space-faring civilization anyway as such would tend to be antisocial and have been bred out of the species just as it has in ours.1 **Is there an alternative?** No, which means that you'll be working with both paths to synthesize the best understanding you can. Your scientists know that a big pile of knowledge will actually be a big pile of rotting Kim-Che, but their superiors won't know the difference, and if they write long enough treatises on the subject, nobody will take the time to read them to discover the conclusions were pulled out of thin air anyway. **But why can't the effort be more valuable?** Because of that "Heisenberg alien uncertainty principle." Because you cannot (and do not) know anything at all about the environment the alien child would normally be raised in, anything you try can and will taint the outcome. You will never see the "true" behavior of the child. Worse, you will never know if what you are seeing is "better" than what you would have seen had you run the test another way. You will always be uncertain. Consequently, you will never have an outcome that will realistically improve your capacity to understand the psychology of the aliens.2 **But that wasn't what I actually asked...** True! What you asked was how to ethically raise a child you know nothing about. The problem is, whose ethics? > > Ethics: moral principles that govern a person's behavior or the conducting of an activity. (Google definitions) > > > Ethics are defined by a society. They are not intrinsic to a species. They're a lie — an important lie. An *incredibly* important lie, but a lie nonetheless. > > HUMANS NEED FANTASY TO BE HUMAN, TO BE THE PLACE WHERE THE FALLING ANGEL MEETS THE RISING APE. > > > “Tooth Fairies? Hogfathers? Little—” > > > YES. AS PRACTICE. YOU HAVE TO START OUT LEARNING TO BELIEVE THE LITTLE LIES. > > > “So we can believe the big ones?” > > > YES. JUSTICE. MERCY. DUTY. THAT SORT OF THING. > > > “They’re not the same at all!” > > > YOU THINK SO? THEN TAKE THE UNIVERSE AND GRIND IT DOWN TO THE FINEST POWDER AND SIEVE IT THROUGH THE FINEST SIEVE, AND THEN SHOW ME ONE ATOM OF JUSTICE, ONE MOLECULE OF MERCY, AND YET— Death waved a hand. AND YET YOU ACT AS IF THERE IS SOME IDEAL ORDER IN THE WORLD, AS IF THERE IS SOME… SOME RIGHTNESS IN THE UNIVERSE BY WHICH IT MAY BE JUDGED. > > > “Yes, but people have got to believe that, or else what’s the point—” > > > MY POINT EXACTLY. (Terry Pratchett, *Hogfather*) > > > So whose ethics are we talking about? Liberal ethics? Conservative ethics? Western ethics? Eastern ethics? Male ethics? Female ethics? Other-Non-Binary-Gender Ethics? Religious ethics? Scientific ethics?3 When you boil the very complex study of ethics down, all we humans really believe is, "Someone has the right not to be hurt and to keep what they have." And not everyone believes even that.4 So, ethically, what's the right way to raise the child? 1. The moment what you're doing becomes known to the public, there will be a crowd of well-meaning but under-educated5 people protesting outside your doors that what you did was unethical from the moment you thought of it. 2. If you raise the child as feral, there will be a crowd of well-meaning but under-educated people protesting outside your door... 3. If you raise the child with humans, there will be a crowd... I hope you get my point. Ethics is a *point of view.* In real life, no matter what choice you make, *you're screwed.* The only choice you really have is how much effort will be required for damage control based on the choice you make versus the value of the proposed knowledge you'll gain. Which, of course, is why the U.S. government has been keeping the Roswell aliens secret at Area 51 since day #1. 😁 **OK, So what's your Frame Challenge?** You're barking up the wrong tree. You need to stop worrying about what the "most ethical method" is and focus on "what are the ethics of my investigators?" Answering that question automatically answers the first. Unfortunately, this new question is too story-based to ask on this Stack. --- 1 *This deserves a bit more discussion. There's a fairly large field of psychological study concerning human primal behaviors in civilized society. It's an issue right now as, at least in the U.S., we debate what is acceptable involuntary behavior and what isn't. While we can argue until the cows come home whether or not humanity has successfully overcome any aspect of its original, aggressive animal behavior with the onset of intelligence and education, the reality is that the answer is certainly yes. The only real debate is "how much?" Or, worse, "how has the original primate behavior changed to accommodate the influence of education and indoctrination in any form?" Frankly, that debate is going to be going on long after everyone who's using this Stack today is long dead — but we have to boil it down somehow for the sake of effective worldbuilding. So, IMO, the influence of humans raising the child would wash away any effective knowledge you can gain from the experiment.* 2 *As I said earlier, your problem is that the species must have evolved to the point of cooperative behavior that subjugates the primal behavior to make room for the intelligent, educated behavior. Otherwise it's unbelievable that the aliens got to Earth in the first place. It's nice to think that you'll find a useful tidbit of information (like the cute little aliens on the Beryllium planet in "Galaxy Quest" that suddenly smile with sharp little teeth and eat their wounded pal), but in reality, there will be precious little of behavior like that. Your aliens, like humanity, had to become* domesticated *to develop the skills necessary for interplanetary flight. That means the only practical differences, other than perhaps noting that they tend to lick their noses like dogs rather than blowing them with hankies, will be cultural, and you can't get to that data.* 3 *This is starting to make sense, right?* 4 *If you want to see someone's idea of what happens when you change the "majority opinion" of what's ethical, go watch one of the "Purge" movies.* 5 *From the point of view of the people inside....* [Answer] ### Do we even know how to raise human children? Answer: Nope. Hard nope. All the nope. Every new parent, without exception, has had the experience of being handed their baby - and then having the realisation that you have this small human which is entirely dependent on you to stay alive ***and you don't know what to do***. Even considering any level of expertise in this from professionals, views on how to raise human children are massively variable depending on society. Read [The World Until Yesterday](https://www.amazon.co.uk/dp/B00AWFEBDK/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1) for a bit of an overview of just how variable that is around the world. To our credit, modern Western societies have done some studies (ethically) and there are professionals in the field who are trying to get the latest ideas across. That doesn't mean the latest ideas are necessarily right, or the best, or even mutually compatible in some cases - they're just the best we can do so far. But then "spare the rod, spoil the child" was also the best that Western society could do up to the mid/late 20th century, as an example of how wrong "the best" can be. So it has to be taken as an assumption that we're ***inevitably*** going to screw up somehow. We can't expect perfection, because we don't have perfection in raising our own kids. ### Let the next generation analyse the problems and react A more general principle though is that if parents really screw up, the next generation can usually see how they've screwed up. So long as they can recognise this as a screw-up (and not see it as normal), they can react to errors in how they were raised and try not to repeat them for the next generation. So whilst things are almost certainly going to go wrong on some level for the first generation, the second generation are likely to have a better shot at it. ### Children are individuals too Even amongst human children, they all have different likes and dislikes. Some may enjoy swimming; some may be terrified of water. If the child turns out to dislike something, or is allergic to it, you change their diet to cope. If the child would rather run around in a field than sit on the sofa and have a cuddle, you spend more time running around in a field. That's what "doing the best you can" looks like. Keep listening to your child - regardless of species - and you're more likely to get it right. ### Children already exist who are not neurotypical The needs of a child with autism and other conditions are often very different to those of other children. If you have a demonstrated ability to work with non-neurotypical human children, you're likely to be just fine with the level of attention and adaptation required to deal with the unexpected challenges here. That doesn't mean you'll be ready for everything, but at least you'll know to be cautious about making assumptions, and to process when assumptions turn out to be false. ### Adoption already exists We have a *long* history of figuring out who can be trusted to look after people's children. And realistically, most people don't abuse the system, or abuse the children. We sometimes get it wrong, but that's mostly down to underfunding of social services so that social workers simply don't get enough time to do a thorough enough job. ### But at least do your best The main thing is to try your best, and if you fail then fail honestly. Many children don't have the best upbringings, and parents/guardians often get things wrong. The most important thing is that the child knows you're doing the best you can, even if things do go wrong. When we've raised these children, they may well decide that they have their own wants and needs which are not human. That's fine. But we're not raising an army who will kill us all off, because at least at a bare minimum they will respect us for having done the best we can, and they will acknowledge that they wouldn't exist if it wasn't for us. Hopefully they'll have some capacity for love and affection, but at least they'll respect us. [Answer] Starting to breed aliens about which we know nothing apart that their biology is very close to ours sounds like the common trope horror movie plot "in this house there is a serial killer armed and determined to kill us, we are scared and poorly equipped, let's split and search for it!". If we don't know anything about the aliens, there is a lot to be learned by anatomical examination of the bodies. If you want to "do right", you do a deep dive into anatomical studies, comparing the corpses and trying to get as much knowledge as you can. You don't play with something if you first don't understand it. [Answer] **They will be raised as humans are raised.** > > Now you must be content to skip ten or eleven whole years, and only > guess at all the wonderful life that Mowgli led among the wolves, > because if it were written out it would fill ever so many books. He > grew up with the cubs, though they, of course, were grown wolves > almost before he was a child. And Father Wolf taught him his business, > and the meaning of things in the jungle, till every rustle in the > grass, every breath of the warm night air, every note of the owls > above his head, every scratch of a bat's claws as it roosted for a > while in a tree, and every splash of every little fish jumping in a > pool... > <http://www.fullbooks.com/The-Jungle-Book1.html> > > > Because who can say we did wrong by these aliens if we treat them as well as we treat our own. This concept has the makings of seriously great fiction. The Jungle Book and Stranger in a Strange Land being two that come to mind. But this is also Frankenstein and Jurassic Park. These are not vulnerable immatures raised by wolves or Martians. These are things that have been raised from the dead by science. Their creation requires purpose but what is that purpose? They are two great concepts and if they have been hybridized before I have not read it. There are many wonderful ways this story can go. Keeping the raising of the aliens simple and in the human pattern will remove unnecessary complexity and highlight the places where the experience of these Lazarus babies different from those of humans - and where it is the same. [Answer] ## you can't *Since others were focusing on practical concerns, I decided to focus on the ethical question exclusively (and dust off my philosophy degree). Please don't take it too seriously. What follows is not an attack on anyone’s moral, religious, or political beliefs. If it comes across as such, please let me know so I can make edits as necessary.* **defining terms** There is a popular conception that ethics is wholly cultural: liberal ethics, western ethics, Chinese ethics, etc. While there is a kernel of truth to this claim, it’s also a gross oversimplification. Philosophically, ethics is an attempt to identify the underlying rules that we use, or should use, to make moral decisions. In this sense the idea that we should not treat people differently based on the color of their skin is not an ethical rule, it is a moral decision based on some underlying ethical principle. Philosophers studying ethics fall into roughly three (oversimplified) groupings: 1. Those trying to identify a universal set of coherent ethical principles that underlie (or should underlie) moral decisions 2. Those arguing there is no such universal set but there are multiple, equally valid sets 3. Those who say there is no fully coherent set at all and that the whole enterprise is a failure All three groups agree that actual human beings living actual lives rarely (if ever) even attempt to apply such principles. In most cases people use an *ad hoc* blend of multiple systems (mainly versions of utilitarianism, deontology, virtue ethics, and care ethics) as part of a system of *post hoc* rationalizations while insisting all along that they subscribe to “[insert cultural label here] ethics”. If group three is correct, then there is no such thing as ethical decision making. For the purposes of my answer, I will assume they are wrong, otherwise the question is moot. For analytical purposes, group one can be treated as a subset of group two. I will thus address the question: can any philosophically coherent system of ethics provide guidance on how this task can be done? *side note: Although often treated as separate concepts in general culture, within philosophy “ethics” and “morality” are synonyms.* --- **finally, an answer** The question proposes to create children as weapons of war. It does not matter that you're not strapping bombs to them. Their reason for existence is war; they are weapons. This is an immediate ethical failure. To be philosophically coherent, a system of ethics must accept that anyone in the same circumstances should act the same way. This raises the simple question: if these were your children, should your enemy do the same? Some will respond immediately in the affirmative. However, just a bit of philosophical scratching at the surface will demonstrate that this is just the *post hoc* rationalization coming in. Perhaps an (imaginary) pure utilitarian can make the case? The utilitarian argument can be based on the number of potential casualties should there be a war. However, this argument fails because the outcome is unknowable. The generals want to be prepared but if the aliens discover what was done, they may very well see that as a "crime against [insert alien species name here]" which demands war in response. **ok, but that's no fun** Let’s sidestep this immediate failure then, and assume the children were created before you came into the picture. They exist, maybe they shouldn't have been created but done is done. Can you find an ethical means of raising them? No, you still have an insurmountable ethical problem. Given that you know nothing of the needs of these alien children, the probability that you can raise them without causing serious harm is essentially zero. Thus, you are willingly and knowingly undertaking an action that will cause serious harm to these children. You have chosen to do something that will result in child abuse. Two quick notes: 1. “If I don’t then someone else will [and they might be worse]” is just *post hoc* rationalization popping up again (although, see below) 2. This is not the equivalent to collateral damage; you didn’t accidently bomb the orphanage because it was too close to the tank, you deliberately targeted the orphanage **so, any way forward?** At this point, if you choose to proceed, you’ll fall back onto a *post hoc* rationalization. There are two likely variants on this: 1. *embrace the evil of difference:* This is what we’d normally call “dehumanization” or "sub-humanization" in that we mentally reassign a person to animal/beast (subhuman) status. In this case it will be easier since these children aren’t actually human. But they’re still sapient and that is what we take away. 2. *appeal to the banality of evil:* This is well known culturally -- you’re just the bureaucrat doing your job. You might disagree with everything about it, but you have a family to feed, etc. Here I would just remind you that Eichmann was convicted anyway. --- [Answer] This is a Frame Challenge. These days, ethically speaking, you don't. You use the biological information already obtained to create vast simulations of growing these alien babies and don't inflict the horrors upon them in reality. First build a huge simulation that mimics human development, clone that into multiple copies and then in each one you introduce just one tiny change of biology that matches what you have discovered. Once you have an idea of what effect that has (and in most cases there will be NO observable effect) you combine a few bits and try again. Your scientists will come up with endless theories on which bits do what, so you always have more variations and options to try. Expensive - sure, but so is growing real creatures and trying to monitor them 24/7. With simulations you can speed up the timelines whenever you need to and get answers in minutes that would've taken decades in real life. The risks of these creatures inflicting damage of any sort (physical, psychological, disease etc) are eliminated, as are all the risks of "ethical" people storming the compound in a bit to free the small vulnerable creatures. ]
[Question] [ **Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/28133/edit). Closed 6 years ago. [Improve this question](/posts/28133/edit) There is a certain art to naming. And I don't have it. But, like any art-form, there are technical aspects which, if followed correctly, can help improve one's overall outcome. Industrial Space Vehicles are spaceships or similar, which are being used for industrial purposes. Imagine typical future Science-Fiction spaceships which are possibly being used to mine from asteroids, build constructions, transfer goods - all those things which an industry would require a specific heavy-equipment-type vehicle for. Is there a process or concrete steps that can be followed to help me select a realistic name for a line of industrial space vehicles? (*A mass produced model of vehicle*) [Answer] ## Capital ships get names. Extend that to all important ships, ones that have done something of notoriety in the past and prototype/field-test ships. Earthly-navies are small enough that most ships represent a significant investment of money and man-power to warrant uniquely naming everything. However, there's lots more space than there is water, so a potential space-navy may have too many ships to give names to. ## Production-line ships get serial numbers. The little shuttle that ferries crew on/off a giant capital ship probably doesn't deserve a name. But it does still need a unique identifier - that's where your serial number comes in. Think of it like registration plates for your car. If your world has lots of private and commercial space-traffic *and* has regulatory authority over space-traffic then licence numbers are the most logical option. If your world is the wild, lawless, frontier then you probably would forego all forms of labelling. ## Generating registration plates/designations. Think of how many ships you want to exist in the world. *In total*, even if they are irrelevant to your story. Times that by ten, or even a hundred. Your licence numbering scheme has to be able to account for that many ships. Any scheme will do, but you might want to devote a few letters/numbers to indicate where the ship was registered, or what planet it's from. By virtue of where I work, I happen to be exposed to how a military labels all their aircraft and boats. Aircraft designators are primarily by role, not by model. I see a lot of aircraft following this pattern; > > AA-### > > > Or, *letter*, *letter*, dash, *number*, *number*, *number*. The first letters is for role. F for fighter, B for bomber, C for cargo, etc. The next letter is for type, the area of the military that owns it, or in some cases both at the same time. The letter S hints that this aircraft is a helicopter operated by the navy. The numbers are completely arbitrary, but are picked by a person. People **love** patterns and rules - it makes organising things easier. Similar models, that are all stationed at the same location would be typically grouped by the hundreds, then counted incrementally. > > CY-301 > > > CY-302 > > > CY-303 > > > etc. > > > * I'm not sure if I'm allowed to use real designations here. I know that they're Google-able, but I kludged together my own rules by substituting extra letters and numbers. ## Generating serial numbers. I'm also employed as an engineer. Past employment dealt with serial numbers for parts. Not whole objects, but I'll go out on a limb and assume the logic transfers neatly. Serial numbers are to track the part back to the precise place and time it was manufactured. Tracking where the part has been installed previously is also a common thing. The rules for these are similar to registration plates on cars. You need to gauge the total number of parts, and round up. Round up *massively*. Part serial numbers need to identify decommissioned/lost/destroyed parts as well as parts currently in circulation. Serial numbers should have the following information squashed down into it: * Place of manufacture: uniquely name the planet+shipyard this thing came from. * Production Line: factories never build one thing at a time. If someone suspects a manufacturing fault, being able to trace it to a production line is a great way to filter out irrelevant ships. * Batch Number: things are often built is batches. This might be irrelevant for ships as they are large objects. * Time of Manufacture: The point in time the ship rolls(read:floats) off the production line. * Sequence Number: the position of the object within the batch. * [EDIT] Part Type: Identify what type of object this is (silly me forgot the most important part). The place of manufacture is probably coded into two/three letters and numbers. Three letters gives you 17,576 unique combinations. Sounds like overkill, but it's future proof, which is a strong deciding factor for accountability. If you want an example of serial numbers, go into the kitchen, collect all your canned and bottled food. Look for printed or stamped numbers on the bottom of the cans. Fast-Moving Consumer-Goods follow these principals as well. ## [EDIT] Keep in mind there may be a disconnect between who designs and manufactures a ship, who uses it, and any authoritative body that's responsible for registration. Each group will likely have their own rules for labelling. [Answer] Based on the comments on your question, I take it you're looking more for *model* names than individual ship names. With that in mind, here is my answer: To start off with, you must figure out what your mining company (or, for the purposes of sci-fi-ness, your mining *corporation*) wants to be known for. Look at [Volkswagen](https://volkswagenutah.wordpress.com/2013/06/13/vw-model-names-whats-in-a-name/): most of their models are named after trade winds, but in German. Thus, they make people think of sailing, the feeling of wind on your face, and German craftsmanship, which roughly translates to "we make good cars that go fast and are fun to drive". If your corporation came up with names instead of serial numbers, then they must have a marketing department and the desire to sell their product; thus, you need to figure out what kinds of things they want their potential clients to think about when reviewing their ships. At the end of the day, you usually have a few options: 1. Make it a foreign word - ooh, you're foreign 2. Name it after an animal - good all-around option 3. Name it after someone famous - probably scientific/nerdy or government 4. Name it after places - nationalistic, probably government-related 5. Name it after mythology - either it's really cool or it's narrative foreshadowing for tragedy Just pick one of these (or any that I've forgotten) and find a name that makes you think good things related to the ship you're naming. To do this well, you're either going to have to know a lot about the ship, or be willing to change some aspects of it to make the name work (which wouldn't happen in real life, but hindsight can make up for your lack of a marketing team). [Answer] If you look at current cargo ship names, you'll see a few trends: 1. Women names 2. Places 3. Nautical terms (star, surf, sea, etc) 4. Company name + something else, like location, or person's name (Exon-Valdez) I think you can follow the same basic pattern - some designation + some of those four category (maybe use astronomical instead of nautical terms for #3). If your world is heavily influenced by corporations, you can put emphasis on #4. If it's more of a "freelancer" kind of place, you can name them after women. Tie it up with the rest of the story. As far as the designations go, the trends are to 1. Describe the propulsion type (SS - steamship, MV - motor vessel, NS -nuclear ship) 2. Describe the purpose (STS -sailing training ship, LB - life boat, FV - fishing vessel) 3. Describe origin (USS - United States ship, HMS - Her Majesty's ship) This basic pattern is used in a lot of fiction works, Star Trek & Firefly come to mind, but others as well. [Answer] The other answers have it covered, except if the ships are sentient. In that case, my favorite naming systems for starships comes from Iain Banks' Culture series: <https://en.wikipedia.org/wiki/List_of_spacecraft_in_the_Culture_series> ``` Class Acronym Description General Systems Vehicle GSV Mobile habitats and / or factory ships, largest Culture ship type. May be home to billions of people. Medium Systems Vehicle MSV Smaller versions of the above. Sometimes former GSVs downgraded as larger GSV classes were developed. Limited Systems Vehicle LSV Smaller versions of the above. Sometimes former GSVs or MSVs downgraded as larger GSV classes were developed. General Contact Vehicle GCV Larger, more capable Contact craft between the size of a GCU and Systems Vehicle; plays similar role to GCUs (see below) General Contact Unit GCU Ambassadors, scouts and light transports; also main warship in peacetime Limited Contact Unit LCU Smaller versions of the above. General Offensive Unit GOU Dedicated main warships Rapid Offensive Unit ROU Dedicated fast warships Limited Offensive Unit LOU Dedicated warships, smaller than GOUs Demilitarized ROU (d)ROU Civilianised ROUs used as courier ships, all or most weaponry removed Very Fast Picket VFP A euphemism for (d)ROU, used in the same role. Picket Ship PS A general euphemism for warships, offensive units or ex-offensive units. Heavy Lifter HL Dedicated materials mover, smaller than GCUs. Superlifter SL Transport craft or tug, a relatively small craft but powerful for its size, described as taking primary military role in early days of Idiran-Culture War before activation of Culture warship manufacture. ``` The names of the ships themselves were always quirky: `MSV Passing By And Thought I'd Drop In` `GSV No More Mr Nice Guy` `GSV So Much For Subtlety` -- a particularly large ship `GSV Just the Washing Instruction Chip in Life's Rich Tapestry` and my favorite, `Mistake Not...` short for `Mistake Not My Current State Of Joshing Gentle Peevishness For The Awesome And Terrible Majesty Of The Towering Seas Of Ire That Are Themselves The Milquetoast Shallows Fringing My Vast Oceans Of Wrath` [Answer] **Determine the focus of the vehicle - what its purpose is** For a mining ship, it might just be the general concept of "Mining" - but there could also be more specialized vehicles. Think Heavy Equipment for construction - You've got Excavators which are used to remove dirt/rock from an area - and move it somewhere else. You've got Bulldozers, which also just move dirt/rocks - but by pushing it. You've got Loaders - which are similar to Bulldozers but are also capable of scooping up that dirt and putting it in a Dump Truck - which moves the dirt farther distances and is capable of dumping it. **Determine the market conditions** In the example above, Heavy Equipment tends to be for specialized use - and certain top companies have the vast majority of creation for all of this equipment. The top 3 in the U.S. * Caterpillar (CAT) * Komatsu * John Deere Since all the focus is on your couple of top-brands, and each maker is making basically the same functionality - the brand is what is going to be advertised. "John Deere Tractors" - instantly forms an image of a green farming tractor. Which tractor do we have here though? Since focus is mostly on the Maker, further specification tends to be named for specific model-numbers which designate which are similar: Such as the 9RX John Deere tractor - largest and most fancy compared to the 9RT and 9R Tractors - (*guess which is smallest*) However, lets say there's a bunch of very competitive brands, attempting to sell their affordable vehicles to the general public. Different brands have different features, and there is competition down to the aesthetics of the vehicles. This is more similar to the car market - where vehicles are separated into different categories for size and general purpose: (Truck, Sedan, Coupe, SUV, Van, Mini Van, Cross Over, etc.) After determining a type of vehicle, the brands compete through their different model names. This is because there are so many types of vehicles and moving targets for "best vehicle" - some makers have much better trucks than they do cars and vice versa. Thus, that model of truck/car earns its reputation and develops a good name, rather than the maker directly. Since the model is developing a good reputation, it develops a good name in recognition of that and to help push itself marketing-wise - while not-so-good models might not have as great a reputation.. but that's just that model, which doesn't impact the overall maker reputation *as* much, since the model name can be dropped and replaced by something newer and better. **Apply conditions to the vehicle, while considering vehicle role** [@DaaaahWhoosh's answer is a good example of this step](https://worldbuilding.stackexchange.com/a/28139/2138) for cars and model names where it's the models that compete - but can also be used for the competing company names. [@user6511's answer is another great example](https://worldbuilding.stackexchange.com/a/28147/2138) for generating serial numbers and identifying vehicles by numbers and type. Many of the other answers cover the case where each ship is basically a one-off construction, and the name the owner gives it tends to become its name. [Answer] My advice is to not just think about a good sounding name, but also a serial number with the potential for **nicknames**. For certain mass produced products, the engineers that develop, build and maintain the product have a habit of making up nicknames for certain models with lots of variations, which each have their own serial designation. Often, even the regular crew will pick up on these, and police forces and criminals alike develop a jargon for these as well. Having people refer to ships with names beyond the one the ship manufacturers and/or owners made makes your world feel more alive and real. [Answer] **The Space-Word Bold-Word** She's a mighty ship, The Space-Word Bold-Word. This will be similar to today's sailing vessels. They'll be named by salty space sailors or corporate marketing departments. If you review very many [large ship names](https://en.wikipedia.org/wiki/List_of_large_sailing_vessels) you see they have a few common themes they're named for. Such as: Name-of-Leader-of-Origin (Lord Clyde), Sea-Term Vessel-Type (Star Clipper), Country-of-Origin (Danmark), etc. The common theme is that the name is lofty, only a few syllables, and is supposed to make you think of greatness, vastness, or strength. Follow the formula for one and use synonyms to avoid repetition. For space mining ships, a believable name might be something like "The Double Double" or "Sol Skipper". Personally I (and a million other people) would name my ship "Ad Astra". The name of the line of ship can follow a similar naming scheme, but it's less likely to be used due to the conventions of sailing ships. It seems most likely that people would be significantly modifying their ships or building them for that single purpose, so space-Mustangs probably won't be a thing for industrial ships, but only personal transports. Those would probably follow a space-themed name of the same style, like a "Mercury" (a fast space thing) or a "Photon". So what about duplicate individual names? **IPv7** They'd like use something like the internet addressing mixed with some Bluetooth protocol. That is, each will be assigned a individually unique computer-readable name for legal purposes (like a license plate, but with enough numbers for a galaxy of ships). Then, from the bluetooth protocol the concept of a "friendly-name" would be adopted (this is kind of also present as DNS for the internet, but that doesn't allow duplicate names). A friendly name is also known as a human-readable name. It's the thing you see when your computer asks if you want to allow "Bob's iPhone" to connect. [Answer] Unless things change a lot, whoever owns the ship, gets to choose the name. If you get that person's character developed you'll probably be able to decide what sort of names he'd give his main assets. At present the owners are mostly governments, which accounts for the uninspired "Voyager" "Intrepid" "Enterprise" etc. On the other hand, Elon Musk (SpaceX) is paying hommage to the late Iain M Banks and naming his spaceship recovery drones after Culture ships: "Just Read the Instructions" and "Of Course I Still Love You". More, please! And for every Behemoth of a mother ship there will be a thousand small service vehicles. I expect these will be too insignificant to be named by the corporation (other than as Asset #192458-2781 "external access vehicle") which will acquire names from those who operate them or work inside them. Visit any port for ideas. My suggestion: assume any popular theme will be pushed to its limits, and then some. If there are spaceships called "Lion" and "Cheetah" then sooner or later there will be a "Warthog", a "Duck-Billed Platypus", and (eventually) a "Lesser Horned Toad". [Answer] In most cases, ships owned by major corporations have a two part name that includes the company name. This allows the owner a greater choice of hull names, because coupled with the company name he only has to pick a name he hasn't assigned to any other hull. The Alcoa Cadet, sunk by a mine in 1942, was one of the Aluminum Company of America's company-owned transport ships. Carnival Cruise Lines puts the "Carnival" name before the ship name, such as "Magic", "Ecstasy", "Elation", "Valor", "Splendor", etc. The Maersk Line has ship names like "Rapier", "Piper", "Alabama", etc, while Exxon's "Valdez" is infamous. Royal Caribbean bucks the trend, naming all their ships with the suffix "Of The Seas", with unique monikers including "Oasis", "Liberty", "Navigator", "Splendor" etc. For an industrial concern, this might be a good pattern to follow; company name and hull name together in one moniker. Your first task then is to come up with a plausible "shorthand" for company names; you can use the name directly, or shorten it (such as with "ALCOA"). As far as hull names, good sources of historical large ship names have included: * Animals, especially water-dwelling or beasts of burden (Dolphin, Lion, Rhino, Barracuda, Marlin, Hawk, Eagle, Pelican, Frog, Dromedary) * Places (cities, states, provinces, geographic regions; country names are discouraged as they can be confused with registry/flag. Military ships often monopolize these, but "City Of" ship names are very common historically especially in transportation) * People (Being a space novel, you might use names of astronomers and space pioneers like Galileo, Copernicus, Von Braun, Grissom, Gagarin, Armstrong, Lovell, etc) * Generally desirable adjectives of a seaman or marine soldier (The British Navy follows this theme a lot: Dauntless, Courageous, Steady, Acute, Constant, Defiant) * Celestial object terms (Quasar, Pulsar, Nova, Constellation, etc) * Mythology (Practically every planet, dwarf planet, and constellation is named for a mythical figure, and oceangoing vessels have used the same; Andromeda, Jupiter, Neptune/Poseidon, etc) * Enterprise. People will think you're ripping off Star Trek, but the U.S. Navy hasn't gone longer than 60 years without a ship of the line by that name, and the moniker was borrowed from the British Navy which has had no fewer than 15 ships by that name in its history including a survey vessel in service today, and the name was also popular in private fleets long before Star Trek used it. * Synonyms for travel or effort (Voyager, Endeavor, etc) [Answer] I Know that in Portuguese Air Force where I work, the Aircraft squadrons as a serial number with three numbers... For example 501 Squadron, 5 means Cargo missions, 0 and 1 means that uses Fixed wings Aircraft (not helicopters)... But there is a nickname of animals for all squadrons, for example this squadron's nick is Bisontes (in English Bisons), this is because they use huge aircraft to transport cargo and paratroopers... In other hand, NASA normally uses names of the ancient Greece, Roman Empire or old Scientists great names as example Apollo, it's all about a Tribute for the past history... [Answer] We have a habit of forgetting that not every spacecraft is something worthy of a special name. With this in mind, you will have at least four categories of space-faring thingies. (NOTE: "Thingies" is important to keep in mind. In space *everything* is space-faring, whether its just a robot, a person's protective suit, a "ship", a probe, whatever. Don't put your brain in a box before you have even considered this by using the term "ship" or "vessel" or "habitat" or whatever.) **1. Definitely uniquely named** Permanent habitats and large "ships" fall into this category. From a technical perspective the difference may primarily be the intended purpose of the structure: To take its inhabitants somewhere, or to be placed in orbit or otherwise remain locally stationary as an improvement on the present-day planet-dwelling arrangement. **2. Uniquely named within a fleet or common group prefix** Unique vessels will nearly always have a unique name, but would probably be a part of a larger effort. We see this in commercial ships today. Not everything is named that is a live-aboard ship, but many are. Nearly every research vessel unique in its class is named, whether inhabited or not. But generally the producing/sponsoring group's prefix is attached to it. **3. Serialized, but not likely "named"** A weaker version of #2; probably having a series name. This will probably include utility devices (manned or unmanned -- I imagine *most* utility devices will be unmanned in the future, many already are today), whatever the equivalent of a family-sized conveyance in space winds up being, etc. We do this with cars, tugboats, small craft, etc. today already. **4. Unnamed, serials may exist but are probably designated by the owner** By far the most prolific form of craft is the mass-produced craft that has a maker's serial number, but usually it is a cumbersomely large number that the owners don't use. Consider a delivery service or fleet of mining trucks today. They have numbers made up by the owner, ("Get me the keys to 5A, yeah, the big 3038-series one") and the actual details of what model it is are subordinate to what job it performs, because there are other comparable alternatives in its class that do a similar job. Consider how this plays out and what class/role comes to mind when you read each name: * *The Titanic* * "Tug #3" * *USN Ronald Regan* * *USN PT-338* * "Cruiser #5, our new AcmeTech Astralon 5000" etc. ]
[Question] [ After reading the question on inbreeding ([Could fictional species benefit from limited inbreeding?](https://worldbuilding.stackexchange.com/questions/2578/could-fictional-species-benefit-from-limited-inbreeding)), I started to wonder if there could be any reasons why an species (intelligent or otherwise) would benefit from intercourse with a non-compatible species (aka bestiality). This could be for any reason, be it social, economic, biological, political,... Any reason. [Answer] The obvious reasons are: * Recreation * Social bonding (for example two intelligent species may use such relations to help bridge gaps between themselves even with no offspring possible) * Establishment of dominance between species * Some other benefit for one or other species. You may not be compatible DNA wise but you may still supply something useful for the process. For example intercourse with a member of species A may help increase the fertility of species B even though it doesn't directly lead to offspring. [Answer] You can have one species plant an egg during the intercourse in the partner who will then raise or be eaten by the offspring (think Alien breeding mechanics). Killing the host is called [Parasitoid](http://en.wikipedia.org/wiki/Parasitoid) behavior but the act of implanting can be viewed as intercourse and is seen in current insects. Though the egg is usually fertilized beforehand though [external fertilization](https://worldbuilding.stackexchange.com/q/1361/858) is not impossible. [Answer] Expanding my comment into an answer: Animals and in particular humans have sex for many reasons other than procreation and essentially all of these may apply to your question: * Recreation, fun and sports * Satisfying psychological needs * Financial and other materialistic advantages (prostitution) * Controlling a partner dependent on sex * Acquiring status * Traumatising one participant or destroying his status, [e.g., for psychological warfare](http://en.wikipedia.org/wiki/War_rape) * Ritualistic reasons, including the establishment of trust or partnership, religious rituals, coming-of-age rituals * Communication – something which can be drastically extended for fictional beings Some possible fictional expansions of these concepts: * While the human impulse for sex is psychological, it could be physiological for another species. With other words, members of this species need to have sex in order to avoid physiological damage or death. As having an urge for sex is a strong evolutionary advantage, this is still plausible. (Of course, there is masturbation, but that may be religously forbidden to said species or actually technically difficult.) * Relatedly, exchanging bodily fluids may be advantageous for reasons other than procreation. To give you some ideas, human sperm also contains nutrients and hormones. [Answer] For intelligent species, the benefits are exactly the same as in intercourse with birth control - no offspring are produced, but people still seem to get something out of it. Even for non-intelligent creatures, the usual non-procreative reasons still apply (pleasure, dominance, social cohesion and conflict resolution, prostitution, etc.). As far as the biological factors, this rather depends on your definition of 'no DNA compatibility'. A horse and a donkey are not compatible in the sense that they can successfully produce fertile offspring. Though they even have a different number of chromosomes, they can produce sterile hybrids (though a few fertile female hybrid have been born, it is astonishingly rare, and no fertile males have been recorded), but they can still produce mules. Getting a little more unusual, depending on what exactly is involved in intercourse, it could involve sharing anything aside from genetic code - intentionally swapping bacterial colonies, administering particular hormones, or providing a nutritional supplement from the ejaculate. [Answer] I feel like people have failed to point out some of the interesting complexity that occurs in evolution; looking instead only at humans sexuality. In fact there are species that benefit from 'sex' without being genetically compatible, in fact species that would not exist without having 'sex' with other species; though admittedly most of these species would not be expected to be sapient. **Send in the lizard clones** I'm a little too lazy to link to each example I'll make, but lets start by talking about probably the most sited example [whiptail lizards](http://www.scientificamerican.com/article/asexual-lizards/). This is a species of all female lizards that still have sex. In their case it's sex with the same species (usually...), but since their all female there is no DNA recombination going on; yet sex is still very important for them! Females who are mounted by other females are more likely to lay eggs and more likely to lay fertile eggs, the mounting makes them better able to reproduce, even though no DNA is exchanged. There are similar groups of lizards (not just lizards, but seems the majority are lizards, due to their DNA structure) that are all female but mate with males of other lizard species. The female will then conceive a female that is a 'clone' of the mother (I put clone in quotes because there are a few ways to produce that clone, depending on approach the DNA of the male may exist within the child but not affect the child's phenotype or be carried on to it's children; making it still effectively a clone). These females may not be able to produce young at all without mating with the males. The reason for these lizards usually comes down to the fact that evolution isn't guided, and can take some strange turns. If your excuse the shorthand of personifying evolution you could say that these lizards started out sexual but then 'decided' to become asexual later so they could spread their genetics twice as fast without wasting time with males. However, they still have a sexual reproductive system that evolve for tens of thousands of years to expect sex, and that is hard to 'get over'. So while the lizards want to stick to making clones they still need sex to help reproduce because they haven't gotten around the fact that they were evolved for sex. In essence the whiptail lizards haven't gotten around to fully evolving away sex and so in the meantime use mounting to simulate sex to help ensure they have young. Of course the whiptail lizards are seen mostly as an evolutionary dead end, odds are they *will* die out, likely without any genetic relatives to take their place, because giving up sexual reproduction is a short term boon at the cost of any long term adaptivity which will kill the species in the long run. However, the other lizards, the ones that mate with males of related species, are a bit more successful. There are actually a multitude of these strategies, which vary mostly in rather or not they keep the male's genetics at all or simply use mating to trigger development of eggs, but these lizards have lasted quite a bit longer and better then we would necessarily expect from asexual species. It's believed this is because they aren't entirely clonal. You see genetics is, again, kind of random at times. It's believed every now and then the lucky males with the offer of free sex manage to be a bit more successful then expected and their DNA manages to make it's way into the resulting child's genome, and the genome of it's children, despite the mother's 'intent' to not use it. These genetic 'accidents' are rare, but common enough to allow some slight genetic influx and thus variation amongst the otherwise clonal lizards. The lizards benefit from still using males by getting some rare genetic variation and thus stick to the seemingly 'worthless' sex. So yes, species absolutely benefit from sex with otherwise non-compatible species and have been doing it for tens of thousands of years!! Of course none of the above lizards will achieve sapience. Without sexual reproduction and new genetics they don't 'evolve' much at all, and the odds of a species like this managing sapience is slim to none. So the above example will meet your requirements, but may be boring to write about. lets move on... **Accidental sex is fun** Of course there is even simpler explanations, mating 'accidents', which can be quite useful. Many species will mate with another species in hopes of reproducing without realizing it won't succeed. (and I realize the use of word 'species' here is going to get complicated by the varying definitions of that word, here I'm including closely related but not necessarily genetically compatible animals). I refer to this as an accident, but animals aren't really thinking about children when they have sex, they are driven by sexual desire and to *them* they mate because it was enjoyable and scratched an itch. They see it as pleasurable interaction, not as an attempt to produce a child that is doomed to fail. They are both happy with this mating. I also should not refer to this as an 'accident' because it is not necessarily genetically undesirable either. Again, genetics is complex and seemingly impossible things can happen at times. It's believed that many species have DNA in them from otherwise genetically incompatible species. This is because even if a species is *usually* not compatible on rare occasions they may manage to produce a fertile child, which may then go on to mate with one of the parent species. This can result in DNA from the 'donor' species to be introduced into the gene pool whatever species the child ended up mating with. This is a huge advantage actually. Genetic variation allows for evolution, but usually genes can only vary through rare mutations. If, however, a rare fertile hybrid is produced and manages to mage with one of it's parent species it will introduce a significant amount of novel DNA into that species. Much of that DNA may very well prove mal-adaptive an be quickly cut out of the gene pool by good old survival of the fittest, but some of that DNA may prove advantageous and manage to be passed on. Thus these rare fertile offspring result in benefiting the overall DNA of the species it mates with by allowing novel beneficial genetics to spread into the gene pool much faster then mutation would allow. **Don't have a cattalo man!** In fact I feel like pointing out the most obvious example of this, modern cows, or more exactly beafalo. Crossing cows with Bison was not unheard of, due to it's producing cattalo that survived in certain climates better. However, to quote Wikipedia > > The female offspring proved fertile, but rarely so for the males. Although the cattalo performed well, the mating problems meant the breeder had to maintain a herd of wild and difficult-to-handle bison cows > > > This was solved when, by random mutation chance, a fertile bull->bison male hybrid was produced. This does not usually happen, it was very rare fluke of genetics. However, this bull was a godsend, and was quickly studded out to as many females as possible, producing the beefaloo. An entire new species due to a rare successful mating of 'incompatible' species; it now makes up a large part of meet you buy in the store. The bull mated a bison purely for satisfaction, and the bison female was only interested in satisfying her own itch. Neither side thought even about the child they may produce, much less their species as a whole. Yet this 'fun' but 'pointless' mating produced an entire new species that benefited from their parent's 'fun'. To further generalize the point of the two above examples I would say that mating between supposedly incompatible species may prove adaptive if there is even the slightest chance of genetic flow. So lets come up with another example of a more sapient species with 'non-reproductive' sex as an adaptive advantage using some theoretical primates based off of our closest genetic relatives. **Monkey Business** In on corner we have our pseudo-chimp, I believe chips are well known and need little introduction. In the other corner we have our pseudo-bonobo. You may not know about Bonobo, which is a shame because they are fascinating species from evolutionary standpoint, and most important for this example make humans look like prudes when it comes to non-reproductive sex. For them sex is social and engaged in for reasons such as bonding, building female alliances (women rule in bonobo land!), resolving conflict peacefully, or as a trade off to get a nice piece of fruit. Now in real life bonobo and chip are quite similar genetically, they are separate species only because they are separated by the Nile, making it difficult for them to meet and reproduce. They are fertile, a male bonobo in a zoo fathered multiple hybrids on female chimps; so they are not non-reproductive. However, for our example lets imagine our pseudo-primates are not as genetically compatible, they can meet up in the forest but usually are not capable of producing young. Now our male chimps may look at that sexy bonobo tail (bonobos have actual tails!, get your mind out of the gutter :P ) and may think it's pretty attractive. Female bonobo's are pretty lax with their matings so it's not too hard to convince them to mate with our males. Perhaps when chimps and bonobo meet up the females offer up sex as their usual conflict avoidance technique and the otherwise far more aggressive chimp males decide that sex is more tempting then attacking, or even killing, the bonobos (which is quite possible, chimps can be violent and territorial). So females offer sex because they don't want a fight and that's a good way to avoid it, the males take sex because...their males; and as it happens they are distracted enough that violence doesn't happen. Conflict is avoided and everyone walks away happy; this already would be a benefit if it worked (though frankly chimp aggression would still be a risk to the bonobos). However, what if the chimps and bonobos weren't entirely non-reproductive. Once in a great while the females manage to produce young with the chimps. Now the females, on average, will benefit from increased genetic diversity in their tribe from these very uncommon matings. The males will have successfully spread their genetics; though unless those genetics filter back into the chimp gene-pool the males doesn't really 'care' from an evolutionary stand point. Perhaps bonobo-chimp hybrids females are more likely to join up with chimp tribes then bonobo tribes when they inevitably migrate from their home tribe; so the hybrid genetics enter chimps as well. Even rare successful matings like this could work to benefit both species. Or lets go from the other way. Maybe chimp females run into bonobo tribes often. Chimps generally are less open to mating so the female usually isn't going to be interested in mating with the sexually excited bonobo males. However, bonobos sometimes offer 'bribes' to females for mating (only small things), so perhaps female lone female chimps have realized that meeting up with bonobos could mean protection and food for a little while, and all they have to do is allow matings that won't lead to reproduction so it doesn't 'hurt' much. This would require a specific evolutionary adaptation for female chimps to realize this, but once realized it's possible lone females may even join up with bonobo tribes briefly while looking for chimps to live with (not that many loan females will be met up with), or the female may offer herself simply for small food bribes. The male bonobo do this because they have a strong drive to mate with females as often as possible and they don't 'realize' the female is not compatible, she's sex and bonobo males like sex. The female does this for brief protection or freedom to accept bonobo's food, she's likely less interested in sex, but it's a simple sacrifice at little cost for what she needs. of course if the chimp female occasionally does produce a hybrid this can encourage this behavior. These sort of interactions could result in chip and bonobo allowing matings somewhat often and benefiting from them on average, in the short term by allowing conflict to be mediated safely and pleasure earned, in the long run through spread of genetics. Over time it's even possible that chimps could take on more of the sex-to-mediate conflict approach when interacting with bonobos when they benefit from it. Now lets say bonobos eventually reach full sapience. They are quite open to matings with chimps and have benefited in it from the past, and their already sexually promiscuous. This could be a standard part of their culture and accepted. It's possible even sapient bonobos won't recognize the occasional chimp hybrid as such for some time, their many matings mean the mother never knows the genetic father and if they hybrid doesn't look too unusual no reason to presume a hybrid instead of just an odd looking normal bonobo. Who knows, maybe the chimps reach sapience, but domesticate the bonobo early on, as we did wolves. In this case domestication of bonobo would likely result in some level of sexual interaction with them, since so much of bonobo society depends on sexual interaction. The chimps could evolve to a point where 'bestiality' with bonobos is no stranger then enjoying to play tag or wrestle with your dog; that's just how you play with a domesticated bonobo. Bonobo benefit from sex because it's how they learn to work with chimps, it's needed to be domesticated and they benefit from domestication; and chimps benefit from having sex with bonobo because it helps them to train and keep the loyalty of a bonobo. [Answer] There are many more species involved than meet the eye at the macroscopic level of perception. Additionally, all life on earth shares a common origin and therefore there is always some level of compatibility of genes: this is how viruses work. ]
[Question] [ I read a prediction that if the global fertility rate stayed at the same rate as it was in 1995 by 2150 the population would be 256 billion people. That sounds crazy, but for my sci-fi I'm rolling with it (albeit shaving off 50 billion). The Hegemony needs to feed these 200 billion odd citizens. One solution I'm interested in is [cultured meat](https://en.wikipedia.org/wiki/Cultured_meat)/"lab meat". Can cultured meat be grown in a industrial scale? And would this scale be large enough to feed 200 billion humans. (Their diets would be supplemented with vertical farming and green houses) Note: Only 30-50% of the population can be fed by traditional farming alone. [Answer] Heck yah. I got yer lab meat factory right here! [![yeast factory](https://i.stack.imgur.com/bm9Fy.jpg)](https://i.stack.imgur.com/bm9Fy.jpg) <https://www.alibaba.com/product-detail/Feed-additive-Brewer-dried-yeast-dry_60078544242.html> This robot factory grows yeast to use as a food supplement. The protein content is comparable to soybeans. You can easily enrich yeast with minerals and in fact this is widely done as the yeast makes the mineral nutrients more bioavailable. The benefit of the yeast is you can grow them in three dimensions on any kind of land or even on boats at sea. The downside is that you need to provide the yeast with everything they need including a nitrogen source and organic carbon to make into their bodies. Soybeans can do a lot of that work on their own, out in a field, using the sun and obtaining their own carbon from the air but they grow only in one dimension and according to the season. [Answer] Ordinary meat takes a lot calories to grow. For example you have to feed a cow 9000 calories for it to gain a pound, and a pound of beef provides roughly 1100 calories. Consuming plants directly would still be able to feed a much larger population that any kind of meat, even if you increased the efficiency of lab meat by 2x or 3x over regular meat. The biology of this planet ultimately relies almost entirely on sunlight for energy. The less conversion steps between raw sunlight and food (sugar, fat, or protein) the less total losses there will be in the system. Having said that, even most plants only capture a few percent of the available solar energy (corn is only 2% to 3%). Where you would gain the most in terms of feeding much larger populations would be to invent artificial photosynthesis to produce 10x or 20x more sugar per watt of sunlight than we get now. [Answer] **Yes (and it will happen fairly soon)** With the advent of 3d printers it's possible to [print meat like products](https://www.3dnatives.com/en/3d-printed-steak-vegetarian-121220181/) from other products. Eventually society will have [algae](https://money.cnn.com/2018/06/01/technology/algae-food/index.html), bacteria and yeast tanks to produce the food we need. The only problem is it's not exactly appetizing. With additional processing, it can be made into products that have the look, taste and even smell of other foods including meat. The tanks can be supplied with the required nutrients and water extracted from processed sewerage and output food and oxygen. Since algae is so fast growing and efficient, it could also replace vegetables as well as meat. As best, real meat and vegetables would be the choice only for the ultra rich. [Answer] **Not really.** Lab meat only replaces meat, which is only a small fraction of the global diet, and you still need to farm something to feed the lab meat, so there are few gains. That said someday it could easily become less wasteful than traditional ranching, just because you are not growing the whole cow and by using plants and plant byproducts humans will not eat and even human garbage. Lab mean does not gain you much in terms of total calories however, because as I said you have to feed it something, so you are still dealing with the the massive energy loss going from producer to consumer. You are still going to use grains for the majority of your calories, the caloric efficiency of grains as producers is hard to beat. Really the globe could feed that population without much problem, the issue would be we would have to convert a much larger portion of the worlds surface into farmland, and start using water intelligently which is going to mean a lot of government oversigt. Aqua culture may be a bigger help than vat meat, since it is literally creating farmable surface, although this will likely only make up for having to farm fuels. That said 100years is a long time technologically by then we may engineered photosynthetic meat cells, if you have that meat is only a little more costly in terms of energy than vegetables, at which point meat would have a similar efficiency as turnips or avocado. That would certainly lower the load on global agriculture but it will still never replace grains in terms of caloric efficiency. [Answer] Replacing meat with a better and maybe more humane substitute is a small part of the solution to feeding the world since meat calories are a small part of a typical diet. There have been a few questions here about the greatest possible production of food per unit of land surface using various techniques. See here: [Giving Tolkien Architecture a Reality Check: Dwarvish Kingdoms](https://worldbuilding.stackexchange.com/questions/100380/giving-tolkien-architecture-a-reality-check-dwarvish-kingdoms/100413#100413)[1](https://worldbuilding.stackexchange.com/questions/100380/giving-tolkien-architecture-a-reality-check-dwarvish-kingdoms/100413#100413) and here: [How can Dwarves produce honey underground?](https://worldbuilding.stackexchange.com/questions/101553/how-can-dwarves-produce-honey-underground/101562#101562)[2](https://worldbuilding.stackexchange.com/questions/101553/how-can-dwarves-produce-honey-underground/101562#101562) And here: [How many people can you feed per square-kilometer of farmland?](https://worldbuilding.stackexchange.com/questions/9582/how-many-people-can-you-feed-per-square-kilometer-of-farmland)[3](https://worldbuilding.stackexchange.com/questions/9582/how-many-people-can-you-feed-per-square-kilometer-of-farmland) And with sufficiently advanced science food can be synthesized from chemicals, like in a *Star Trek* food replicator. [Answer] They are working on doing that now lab meat (though to the scientist and their polling working on it) they say it's very important for it to look, feel, and taste like the birthed thing. They currently take cells from a cow or whatever and grow it in the lab they say it is possible but right now it will take years to do that. Just assume you've gotten the break through required to do it either a civilian tinkering in their garage came up with it (as a hobo built himself a home made nuclear reactor for his own shanty power system not kidding). So the civilian tinker in this example figures it out small scale then talks to the government or took it to a manufacturer and solved the issue so now its possible. Or the government threw enough money at the labs and their scientist to make that occur or Japan figured it out ect. I think its growing speed, portion sizes, and getting the population to see it as safe and natural. Bare in mind real meat would become something for the rich to consume (for prestige and health) all other classes would be given the lab meat the current plan being to just phase it out and not tell anyone as they're so close in comparison. People could be allowed to further supplement their own lives with their own gardens indoor in their basements or housed in dried swimming pools. Or you could also allow for yard farming but that depends on how much space your society allows for people to take up. They would also outlaw personal farm homesteads so meat could not be sourced from that location it won't stop everyone but then you also have to consider what do you do with the Amish and people who for religious or personal reasons will not eat what they consider to be false meat? Will there be a black market for the real deal? And how will anyone know? One devious thing would be the government in reality controls both ends of this meat pipeline and its all fake save the approved people who get it via they're on a list or are the actual animal providers themselves. ]
[Question] [ A very powerful funeral company offers fossilization as burial options to very rich clients. Of course, no one can check if it would actually work in a few million years, but the company shows great power and influence and has strong arguments that it could actually work. What would this arguments be, so rich people actually believe it? What would the burial processes and the after funeral precautions would be? [Answer] ## Natural Fossilization is not that slow of a process Okay, so I did a bit of research and as it turns out natural fossils can actually be formed much faster than I previously stated, meaning that quite authentic fossils could be created by a funeral home in a reasonable amount of time. Basically you just need to put the body in a coffin full of finely ground calcium and silicon. As the bacteria in the body decomposes it, the calcium and silicon will react with the body's organic molecules to reform into the calcite and silica which forms the crystalline structure of a typical fossil. While I can not find any experiments done on human sized fossilization, a shrimp can fossilize in just 4 to 8 weeks using this method. Large animals like humans are believed to take closer to a year. Since there is not much labor involved, this means the cost would come down mostly to materials. Calcium silicate costs about 2.66USD per liter. If we take some calculations I did for this question <https://worldbuilding.stackexchange.com/a/175242/57832> a while back, we see that an average person fits into a 143.52 liter box, while himself having a volume of 58.5 liters that means that this whole process will only require a coffin filled with about 226USD worth of minerals. Just tuck the body into a mausoleum and pop it open after a year has passed and you have a fossil just like mother nature makes to prove it works. Also fossilizing a body means you don't need to embalm it; so, not only is this an option for the very rich, price point wise it would probably be somewhere between embalming and cremation. Especially since you only need to rent the coffin and burial site for a year instead of buying them out right. When you are done, you can take the remains home to be put on display as you would with a cremation. [Answer] **Happily for you, this service already exists!** Fossilisation simply means the replacement of soft body tissues with some kind of mineral, a non-biological substance. Usually the process takes squillions of years and, as you indicate, there's no guarantee it'll happen to you naturally. So let me introduce you to the concept of ***body plastination***: [![enter image description here](https://i.stack.imgur.com/jVzTb.png)](https://i.stack.imgur.com/jVzTb.png) Yep, that's a real guy. What's left of a person after undergoing the process of modern fossilisation --- **[plastination](https://en.wikipedia.org/wiki/Plastination)!** Essentially, the body is treated to a four step process of fixation, dehydration, vacuum impregnation of polymers, and hardening. The result is, essentially, a plastic fossil. As far as credibility goes, you (or rather, your kith and kin) can see the results in a couple months rather than a couple spentillion years! [Answer] What you'd really be selling is the concept of a legacy, and that Fossilization was the way to secure it. Historically it's been remarkably easy to convince the rich and powerful to spend vast amounts of money on their funeral rites, from the Egyptian Pyramids through to more modern practices like naming civic instutitions (theatres, hospitals, charitable foundations etc.) after their benefactors. Why specifically fossilization? Certainly it could initially be sold on a novelty appeal: "become the first Human Artwork" and longevity "only fossils can last 100 million years". Once you have a few initial successes it could easily be made into somewhat of a fashion trend "Tragic Hollywood star Tom Rex did it, it's all the rage now". At this stage the high price and exclusivity can start to work in your favour as people clamour to join an incredibly elite fossil club. [Answer] How do you fossilize? ["First, the soft tissue that exists during life decays leaving behind only the "hard parts" (bone, shell, teeth). Second, hard parts may be transported and broken. This causes the fossilized remains to be incomplete representations of the living animal. It is much more common to find a fragment of shell or bone than it is to find a complete skeleton. Third and most important, hard tissues become buried and altered. In most cases this involves **destroying the original material** from which the hard parts were made as minerals are slowly dissolved and replaced by new ones. Often times a hard part is dissolved without being replaced by new material, leaving behind only an **impression or mold** of the original animal. If this mold is filled with sediment that is later cemented into rock it will make a cast of the original animal."](http://geology.isu.edu/Alamo/fossils/process_fossilization.php) Fake fossilization. Use advanced computer modeling to create a virtual [mold](https://www.sciencedaily.com/releases/2020/01/200108102259.htm)\* of the person and 3D print it. Show the client the simulation of "themselves" and then proceed to bury them as normal once they pass away. If your company is still around in a few million years\*\*, then they can just show the (suspiciously perfectly preserved, because of course it is not organic) 3D printed model. \*Well, yes, I know this is a microorganism. Doesn't matter and should even be superior preservation with non-organic materials. \*\*Assuming your company even still cares. I hope this helps! ]
[Question] [ I have an idea for a story set in a not-too-far future where the political lines of the world map have been redrawn, not by nation-states like France or Belgium but by corporations like MacroCorp, Branson Genetics and The Co-Operative. Huge industrial conglomerates literally control entire nations as our governments do now. Elected governments still exist but are as much figureheads as the monarchs of the 20th-21st century; in practice they are totally beholden to the CEOs and executives that have all the actual power over writing laws, international diplomacy and so on. I think that a pessimist would already see the signs that this is happening, between the hefty power of corporate lobbyists, politicians with investment portfolios that betray clear conflicts of interest, creeping privatisation of public services like hospitals and police forces, and international trade deals that erode governments' ability to oversee corporate collusion (TTIP lets corporations sue governments for endangering their profits!). But what I'm looking to brainstorm is some kind of big historic event that marks the dividing line between our world and this one. Something on the scale of the fall of the Berlin Wall, the collapse of the USSR or 9/11. Creeping government legislation to permit this will definitely have happened, and is certainly a huge factor, but I want something that the citizens of this world can point to and say “It sure hasn't been the same since X.” It's possible that this was some big bit of international law that allows a corporation to legally purchase a city (because I like the idea of referring to cities as business assets; and The City of London Corporation is something that already exists), but even that doesn't seem revolutionary enough for this level of societal shift. Perhaps over several decades our mega-corporations became more powerful than the biggest world governments in terms of GDP, intelligence services, military might etc., and the big watershed was some kind of civil war between some major G7 nation and UberCorp PLC that the government lost, and was overthrown. After this the other corporations realised that they could easily do this too, and the governments of the world fell in line when they realised they couldn't stand up to the business leaders. But this might be too simplistic, or too jingoistic, or not nuanced enough - just an idea to start off with. Also, if anyone has any recommended reading for fiction that has done a similar thing, I'm all ears. Brave New World kind of skirts this line (Thank Ford) but has a very different focus. I know books have probably been written about horrible corporate dystopias but I'm not exactly sure where to find them. [Answer] You're asking for a single, large event to cause the shift, which makes sense as the *end game*. However, I think it's probably more important to establish a series of events and circumstances which set up the situation such that it will culminate with corporate takeover. **Presently** Globalization is the word of the day. Large corporations have become international entities with no *real* ties to their country of origin. They are interested only in the bottom line, and scoff at having any sort of civic responsibility, or really supporting human rights (except when the cameras are trained on them - look at present day Apple factories in China). Look at the US, for an example of "rabid capitalism": corporations are legally considered "individuals", which allows them to lobby government. They blatantly manipulate politics, and influence major decisions in many areas. This is true all around the world in some way, shape, or form (by having politicians, or their families be involved with said corporations, and thus act in their favor, etc), however in most places corporations don't *legally* have that kind of power. Thus, it's unrealistic to suggest that corporations would, in one fell swoop, take over the world - or even just the Western countries. People would resist, the military may even rebel. What you need is a good combination of ***legislation and circumstances***. **The Set Up** There's several aspects which need to be staged: * An economic/security crisis which make people desperate * Increased corporate rights and freedoms * Government ineptitude in handling the above crisis These conditions will be met slightly differently in the US and Europe. ***Europe*** To address the first condition, simply extrapolate current European events: the immigrant crisis of Europe takes a heavy toll on socially generous countries such as Germany, France, and other Northern European nations. Terrorist incidents shake the public's trust in the judgement of their governments (they let the immigrants trample across borders unchecked), as well as their ability to keep them safe (a lot of arrests are made, but dozens of terrorist attacks still occur). This situation sparks a wave of racism and Islamophobia which sweeps many European nations, and which results in many demonstrations and acts of violence against Muslims, and their places of worship - this in turn fuels even more violent acts on the part of their extremists. As a result of the unstable security situation, the EU's economy suffers greatly. In an effort to bring the economy back on track, and under heavy pressure from the private sector, the EU grants corporations rights similar to those of US based entities. There are groups which protest this, but the average citizen is desperate for a job, and to feed his/her family: they just don't care anymore. ***The US*** The economic downturn brings a lot of people to desperation. Robberies and violent crime rates rise, as does the aggression with which police deals with the heavily armed (Second Amendment, yay!) perpetrators. Racial tensions rise, with each police shooting, and violent demonstrations and riots take an even greater toll on the US economy. Public trust in the government's ability to keep them safe, and run the country, drops. ***In Both*** Large global corporations band together and announce a US-EU public service project on a massive scale. They begin opening large community centers in the hardest hit European and US cities, and publicly pour a large amount of money (but only a fraction of what they have, not to mention also receiving government funding) into making these a success. They offer employment services, open food banks, child care services, etc. - all while providing jobs for the locals. To protect these community centers, they set up *safe-zones* which are protected by private corporate security. They - very publicly - succeed: * Europe: in stopping several planned terrorist attacks against these centers * The US: in stopping riots from sweeping over their safe-zones, which keep thousands of women and children safe as rioters rip the city apart around them Public opinion on the abilities of corporations to keep the peace skyrockets. As Draco has already stated, corporations already have access to an unprecedented level of information, as well as basically owning the Western media. By carefully manipulating the media, and going so far as to manipulate/edit popular internet sites and forums etc., corporations build a truly impeccable image for themselves, with any incidents involving corporate security violence being swept under the rug, or being very well handled by their PR departments. All around the US and Europe municipalities ***ask*** the corporations to expand their security zones to include schools, hospitals, and other civic buildings. The corporations agree, but request a greater degree of freedom in managing those areas. **The Grand Finale** As stability returns, so does prosperity. Municipal governments already work very closely with corporations, while at a higher level (US federal, and EU government levels) lobby groups are keeping just the right people funded and in power. After yet another major government fuck up (many troops dying in the Middle East, etc.), which corporations are careful is played up in just the right way in the media, a seemingly "grassroots" movement is sparked: "The people", clearly seeing that corporations can better manage their countries than their failed, war-mongering governments, demand that these same corporations which have restored their cities take over greater government functions, including foreign policy. This whole thing is carefully manipulated via social media by the corporations in question, while the alphabet agencies (CIA, NSA, CSIS, Interpol, etc.) have their leashes yanked by corrupt politicians, or other well placed corporate puppets. After massive referendums across the US, Canada, and the EU, this massive global corporate conglomerate is *elected* as the managing entity for the Western world. The corporate leaders become public figures of incredible importance. Each country's military/police force/spy agencies, while technically not falling under corporate rule, now depends on them for funding. Needless to say, the takeover is fast and merciless, with public opinion being manipulated all along the way. > > Note: As Avernium points out, corporations are a bit like cats: they compete, not work well together. You would have to also cover how major corporations would initiate this massive effort. No wand-waving required as far as you keep in mind that what they all really want is money. You can imagine a company such as Amazon buying Walmart, then merging with Microsoft/Google/Facebook/Ebay, and becoming a behemoth of unparalleled influence and financial might. Once they have that much power they can bully any other company into bowing down to them (weapon manufacturers, pharmaceutical companies, etc.). Other companies would offer to join their alliance simply to stay on their good side. > > > [Answer] The question could be rephrased as, "what kind of historic event would eliminate the difference between corporations and government?" There are several significant differences. For example, a government can issue money and levy taxes; a corporation can't. A government can pass laws and enforce them; a corporation can make rules that apply to its employees, but its ability to make rules and enforce them is limited by the laws of the place(s) in which it does business. If a corporation tried to do things that are generally considered the exclusive province of governments, it would incur the wrath of the government, which would bring down problems upon their head in the form of financial penalties, law enforcement, or possibly military action, depending on the severity of their transgressions. To be able to get away with this, they would need to be able to withstand such wrath and come out on top. Therefore, what would be the tipping point? *Corporations beginning to successfully field their own law enforcement and military forces.* One scenario I've seen in which this occurred in fiction is in the *Shadowrun* backstory. Essentially, during a time of serious unrest due to food shortages, there was a train traveling through a major American city, filled with toxic waste. Rumor got around that it was actually filled with food, being shipped off to rich people while the common man starved, and a riot ensued, with people trying to storm the train. (It's heavily implied that the rumor was seeded deliberately by corporate interests to precipitate this exact chain of events.) Heavily armed private security on the train fought to defend it, killing many rioters. The company that owned the train ended up in court, for unlawful military action. They presented the defense that if the rioters had successfully stormed the train, they would almost certainly have contaminated a large part of the city and caused millions of deaths and severe injuries, and that the guards' work in protecting it was a massive public service. The courts ruled in their favor, and this set a precedent: corporations can have their own armed forces to protect their interests. And it was all downhill from there. There are other ways it could play out, of course, but finding some way of legitimizing corporate military is the most likely single tipping point. [Answer] A conglomerate of Private Military Corporations (PMCs) defeats ISIS/its descendants. ## The Setup Donald Trump gets elected in 2016, and with Congress, passes laws alienating most of the Muslims in the US and most Western nations. France, the UK, and several other major nations follow suit. ISIS ranks swell, and terrorism flourishes around the globe. Voters demand action, but are unwilling to send their sons and daughters to fight and die in the Middle East. Meanwhile, PMCs like Blackwater/Academi win bigger and bigger contracts for providing security in these increasingly dangerous areas. ## The Event ISIS decides that to instigate the apocalyptic battle it fervently desires, it must target the heart of Capitalism. It organizes sleeper cells to kill family members of major corporations, including Facebook, Apple, Google, and Microsoft. Mark Zuckerberg's wife and child are gunned down by agents who have pledged loyalty to ISIS, and Zuckerberg himself vows revenge. He buys Academi in a trade executed entirely with shares from his charitable LLC, and nobody in the media raises a finger in protest. Marissa Meyer's young child is also murdered by ISIS, and she convinces others with a similar plight to also buy out the largest PMCs. Veterans from former wars swarm to sign up with the PMCs, who are now flush with cash and offering large recruiting bonuses. Even though the world gov'ts are hamstrung by electorates unwilling to send their militaries into the fight, the PMCs have both the freedom and the economic power to do so by themselves. Zuckerberg forms an alliance with Larry Page, Nadella, Tim Cook, and Mayer to send in a combined force to wipe out ISIS once and for all. Jeff Bezos offers to help with militarized drones converted from his delivery network. Fighters come from Somalia, Kenya, Burma, Malaysia, Albania...every conflict zone from the last 3 decades, all in search of money and glory. NATO and Russia at least offer air power to neutralize the biggest threats, but their commanders are otherwise forced to look on as the PMCs engage in the biggest fight of the decade. From their war room in Silicon Valley, the tech giants of the world unleash the biggest volley of privately controlled weaponry in history. After a bloody but quick battle, ISIS is not just defeated, and demoralized, but eradicated. Many of the mercenaries commit war crimes against ISIS fighters in a brutal display of bloodlust and revenge, but there are no calls for ICC tribunals, as Apple's production team pushes propaganda videos around the clock showing the innocents being slaughtered by ISIS in the initial strike. ## The Aftermath Now that private corporations have formed a huge fighting force, it becomes apparent that they actually have the largest military in the world, outranking even the US and China. And, fueled by the righteous anger of victimhood and revenge, Zuckerberg and friends promise to protect the world from any menace that may arise, anywhere, at any time. Bezos and Elon Musk launch anti-satellite and ballistic penetrators using Falcon and Blue Origin rockets. Together, it is clear that the Corps now call the shots, and it really doesn't matter what any gov't has to say about their actions. Since they are initially viewed as the saviors of mankind, their actions are tolerated, at first...but power corrupts. Absolute power corrupts absolutely... Some elements of this can be seen in the latest Call of Duty game. [Answer] This is the site for building neat **fictional** worlds, not for stringent historical analysis. With that in mind, here are some options: * In a major western nation, a corporation publicly threatens to move their corporate headquarters to another country unless the newly elected government resigns immediately. The government complies. The press conference and the hours leading up to it are the "where were you when ..." moment. * A mid-sized newly industrialized nation declares that they cannot pay their debt. Corporations sue in trade arbitration courts and win. After some behind-the-scenes wrestling, a highly improbable coalition of national governments invades the defaulter to collect the debt. They go in, loot the central bank, museums, etc. Either the declaration of war or the news reports from the invaded capital are the "where were you when ..." moment. * A trade arbitration court declares that a decision by the US supreme court is invalid because the SC doesn't have jurisdiction. (A similar scenario in the EU would be less traumatic, people are used to the ECJ taking national cases.) [Answer] My (least) favorite answer would be: ## Nothing The world is already going that way and it would take *doing something significant* to **avert** that future. Google and Facebook collectively know more about us than the NSA does, selling that information to advertisers in order to brainwash us into buying [NERPS](http://shadowrun.wikia.com/wiki/NERPS), and we're complacent enough to go along with it: Afterall, any pleebian who isn't buying doesn't know what it's like to really live a comfortable life. We're happy to turn our social lives over to a cloud service, let our actions be [dictated by our devices](http://www.gocomics.com/doonesbury/2015/12/06), and expect instant gratification from everything. If it takes longer to download a movie than make popcorn, we throw down the remote and find something else. [Would you like to supersize that?](http://pixar.wikia.com/wiki/Buy_n_Large) [Answer] After trying to come up with some interesting major historical events that might precipitate this situation, it has become increasingly clear that **no single event could be responsible**. A tipping point might be identifiable, but in every scenario there is a multitude of events that need to happen to reach your destination. Here are a few of the reasons why: 1. **As of the present day, the majority of citizens in western nations are ideologically against corruption.** More fundamentally, they are against unequal influence (particularly the opaque type) of government officials. Given that business interests are often a prime motivator for corruption, any single event that allows a visible shift in governance from elected officials to corporations would probably not be accepted peacefully by the populace. 2. **A large-scale destabilization of federal governments would result in a retreat toward smaller local governments** where citizens can more easily hold officials accountable. This is a big problem for a lot of scenarios, because a loss of trust in government is unlikely to allow corporations to swoop in as the good guys. The highest risk of destabilization would be with a single high-profile event, whereas many smaller events over a long period won’t disrupt the status quo. 3. **There are many, many corporations within each country**. For nation states to be replaced by corporate states, you would need to either have most western countries subdivided into smaller states ruled by individual corporations or certain regions (such as Silicon Valley) would just erupt into chaos as the biggest corporations vie for violent or financial takeover of each other until one comes out on top. 4. **Few, if any, corporations are diverse enough to govern a region.** Currently, the most profitable companies in the world only specialize in a few specific areas (relatively speaking). If they attempt to acquire companies across the full spectrum of services they will become too slow and lumbering to adapt to changing markets and they’ll be at risk of collapse. These companies also don’t employ militaries for defense. While private military contractors certainly do exist, it would be beyond suspicious for your typical Google or Amazon to acquire one of these companies. And bear in mind: whatever they plan to do with those soldiers, the soldiers are ultimately citizens who may or may not agree with what they’re told to do. When you ask too much of a soldier, “orders” no longer becomes enough of a justification. 5. **For corporations to function, human beings must be employed**. Automation will replace some jobs, but large companies will continue to employ large numbers of people and doubly so if one of them is governing a region. Using force to get employees to come into the office isn’t going to be practical — you need people to do it willingly, which takes a buildup of either trust or dependence, both of which take time. If a corporations employees don’t come into work — whether it’s due to an ongoing revolution, general distrust, or something else — it will not function. As a result, the so-called “slow boil” is not only going to be the most believable scenario to present-day readers, but it’s probably the most likely. [Answer] # The Second Great Depression An economic event like the great depression hits the world economy. Huge numbers of businesses are floundering. You might think this would hurt the power of corporations, but that's not how things worked out: Some businesses are bailed out by the government. But when things don't get better, they come back for more and more bailouts. Soon, the businesses are taking government funds just becomes part of doing business. If anyone objects, its pointed out that the business provides a necessary service, if it were allowed to go under, we would all suffer. The number of businesses able to donate to election campaigns shrinks. Politicians are more desperate to get those campaign donations, leading them to be more in the pocket of businesses than before. [Answer] [Game theory as a dark art](http://lesswrong.com/lw/dr9/game_theory_as_a_dark_art/) - Take one: evil plutocrat. > > You are an evil plutocrat who wants to get your pet bill - let's say a > law that makes evil plutocrats tax-exempt - through the US Congress. > Your usual strategy would be to bribe the Congressmen involved, but > that would be pretty costly - Congressmen no longer come cheap. Assume > all Congressmen act in their own financial self-interest, but that > absent any financial self-interest they will grudgingly default to > honestly representing their constituents, who hate your bill (and you > personally). Is there any way to ensure Congress passes your bill, > without spending any money on bribes at all? > > > Yes. Simply tell all Congressmen that if your bill fails, you will > donate some stupendous amount of money to whichever party gave the > greatest percent of their votes in favor. > > > Suppose the Democrats try to coordinate among themselves. They say “If > we all oppose the bill, then if even one Republican supports the bill, > the Republicans will get lots of money they can spend on campaigning > against us. If only one of us supports the bill, the Republicans may > anticipate this strategy and two of them may support it. The only way > to ensure the Republicans don't gain a massive windfall and wipe the > floor with us next election is for most of us to vote for the bill.” > > > Meanwhile, in their meeting, the Republicans think the same thing. The > vote ends with most members of Congress supporting your bill, and you > don't end up having to pay any money at all. > > > It not only can happen, it is slowly happening, because many voters (in USA) cannot be bothered to learn real facts, and rely on biases and misinformation (financed by the same plutocrats). Requirement of democracy is **informed** electorate. Oops. [Answer] Not wanting to get all political (I'm not even American), but here is a scenario. Donald Trump is elected president, and with a house and senate majority, immediately starts to deliver on his promises to reduce the size and cost of government and invigorate business by outsourcing all of the Government's functions, eventually including (for sound economic reasons of course) the legislature, the judiciary and finally, the executive. As part of this push laws are passed giving corporations enhanced rights and powers where it is needed to fulfill their functions. For example, private police forces need to be able to carry and use weapons, and so are exempted from prosecution for such. Of course, the legislation was developed by corporate "advisors" in the legislative branch and is full of loopholes and exceptions advantageous to them, such as allowing the corporations to engage in asset forfeiture and keep the proceeds. With this power over the running of the USA, and the various binding trade agreements in existence, other nations are forced into similar situations. Those resisting are sidelined via by multinationals wielding their immense economic power. [Answer] If general opinion becomes in favor of a big company rather than the government. * Imagine a series of terrorist attack of nuclear proportion and the government unable to react. * Than for example a google pinpoints the exact location of the terrorist cell. Sends also some androids there to eliminate them. * Attacks stop. Google posts its actions on youtube. * Upcoming election I would vote google. * Next thing you know, there is a giant google tower in middle earth with a chrome logo on top. Just kiddin, google, we love you [Answer] Political power grows out of the barrel of a gun (attributed to Mao, I think). You need an event that allows the corporations to have their own armed forces. Perhaps, a constitutional amendment in the US privatizing the armed forces for cost savings. Or a stronger second amendment allowing individuals and corporations to keep and bear any weapon they like, including nuclear weapons. These are unlikely to happen elsewhere in the world but US corporations may slowly take over the world with their armies. [Answer] ## **The Solar Flare** The World has become all but dependent on computers, when all of a sudden, the Sun emits a solar flare in our direction with a powerful enough EMP to wipe out all electronics. The ensuing chaos causes the fall of governments worldwide. The world plunges into a deep economic depression, law and order breaks down everywhere and the people begin to starve. However, it turns out that some of the biggest corporations had put aside some of their spare billions to keep backup systems deep underground, well protected from the effect. They have all the information they need on most of the world's citizens, and just happen to have the expertise and knowledge to provide the various needs of the people in massive enough quantities. All you have to do is pledge your loyalty to them. So you can try to work together some semblance of democracy, you could try to live an agrarian life or set up some sort of commune / soviet, which is hard work with little reward... Or you could take the easiest option and just join the corporation, and eat. ]
[Question] [ **Setting:** Modern Earth; technology no more advanced that what's reasonable within the next thirty years. **Premise:** A prehistoric (and broken) alien device is discovered on Earth, and researchers determine that it was built to allow either time travel or teleportation (or both). Scientists reverse engineer the device to create a crude (and functional) version. They send objects through, and are able to retrieve them. **Technicals:** The human-built version of the device actually sends objects far into future (ie, 1 X 10 Googols to the Googolth power years), far *far* past the heat death of the universe. They appear in empty (inter-galactic) space, and displace any atoms which may be present. **Question:** What effects/forces would these objects experience in the dead universe, and what effect would their sudden presence have on a universe which has long since reached a stable/maximum entropy? More specifically, would an astronaut in a modern space suit be able to survive in such an environment for more than a few seconds? [Answer] If the [Grand Unification Theory](https://en.wikipedia.org/wiki/Grand_Unified_Theory) is right, then there would be *no* atoms at all left in the universe by the time you have mentioned. This would occur due to [proton decay](https://en.wikipedia.org/wiki/Proton_decay). By this time probably all black holes would also have evaporated due to a phenomenon known as [Hawking Radiation](https://en.wikipedia.org/wiki/Hawking_radiation). [Maybe even photons can decay](http://physicsworld.com/cws/article/news/2013/jul/24/what-is-the-lifetime-of-a-photon) into lighter particles. ***If these theories are right*** then there would be no universe left at all. Perhaps not even space and time. According to some theories, space and time can't exist without matter while others posit the fabric of spacetime can exist independently of the existence of matter. We just don't know yet. If some of the theories about the core reality of matter and spacetime happen to be true, all the *physical objects* (including photons) would have *evaporated* out of existence and the very fabric of spacetime would have been wrapped by then. Which suggests that the universe would have ceased to exist by that time. [Also read this article. I found it very informative.](http://news.nationalgeographic.com/news/2010/10/101027-science-space-universe-end-of-time-multiverse-inflation/) **Note:** This article (the one mentioned above) was written in 2010. While being very interesting and informative, do not jump to any quick conclusions based only at this article. Read it to increase your general knowledge about mathematical models about the fate of universe. [Answer] I'm assuming you're talking about the classic heat death, rather than any of the other theories that have come about from time to time (such as the "big rip"). In this case, to all practical purposes, the post-heat-death Universe would be not much different from the vacuum of space as it exists today. The main differences would be (i) there would be no starlight or light or matter of any kind, and (ii) there would be no detectable cosmic microwave background radiation, or indeed any detectable radiation of any kind. All the radiation is actually still there, it's just that the Universe has expanded a lot since today, and the radiation has expanded along with it, converting it to such enormous wavelengths and low intensities that it could never possibly be detected. The matter, on the other hand, really isn't there any more. It was all converted into black holes very long ago, which then evaporated into electromagnetic radiation over trillions upon trillions of years; that radiation has since been stretched out along with all the other radiation. So the universe they find will be black - completely and utterly black beyond all conception of blackness, and cold - completely and utterly cold beyond all conception of coldness. But since space is already pretty cold and black in our time, the space suits we already have would be perfectly good for surviving in it for a time. As for the effect the astronauts will have on the universe: well, they're emitting a lot of infra-red radiation, along with their radio signals and any visible light from lamps they have with them. That radiation will spread out from their position at the speed of light, and keep going pretty much forever, though in the general scheme of things it won't be all that long before it too is stretched out to undetectably long wavelengths and to all practical purposes disappears. They are also very likely to leave behind them some atoms even if they make it back somehow, due to gas leaks, propellant, dust particles and what have you. In the absence of any black holes those atoms will last for quite some time, but they will probably eventually decay to electromagnetic radiation through some process or other. Though if they happen to have left a net charge there might be a few electrons left over, which can never decay because there are no protons left in the entirety of the rest of the Universe. It's a tiny mark to leave on the Universe, but it will last for all eternity. [Answer] The simple answer is that we just don't know. The most likely thing is that you would appear in the hardest vacuum ever measured, living inside your space suit for a while, and then disappear. Once you disappear the slightly energized area where you shed a bunch of atoms and photons and suchlike will gradually disperse and return back towards heat-death in a brief and feeble pulse of somethingness against the vast nothingness. On the other hand though if the entire universe has stopped existing by then...well that clearly can't have happened since you've traveled to something... [Answer] > > *More specifically, would an astronaut in a modern space suit be able to survive in such an environment for more than a few seconds?* > > > Oh that poor astronaut. In addition to the other excellent answers about the state of the universe (or lack of a state) that far in the future, there's also the problem of ***[The Big Rip](https://en.wikipedia.org/wiki/Big_Rip)***. The expansion of the universe is accelerating. This means ***the space between everything is getting bigger*** like the surface of an expanding balloon, except that surface is 3 dimensional space. If it keeps accelerating, as it appears to be, ***eventually it will be accelerating so fast to overcome the fundamental forces that hold things together***. First, gravity will be overcome. Galaxies will fall apart. Then solar systems. Then stars and planets and other bodies held together by gravity will disintegrate. Then electromagnetic bonds between molecules will be overcome and complex structures, such as people, will be torn apart. Then the molecules themselves will be ripped apart into atoms. Then their electrons will be lost. Eventually the acceleration will become so fast the strong nuclear force will not be able to hold atoms together. Then protons and neutrons will be pulled apart into quarks... You get the idea. ***Ultimately, if the acceleration continues, the universe will be expanding faster than the speed of light.*** (This is ok because ["the speed of light" is actually the maximum speed of information transfer between two points in space](https://www.youtube.com/watch?v=msVuCEs8Ydo), space itself has no such limitation). At this point no information can be transferred between two points in space, they're moving apart too fast. The universe is dead. What does this mean for our time traveling astronaut? ***They're immediately torn into a cloud of fundamental particles expanding in all directions faster then the speed of light.*** Good epitaph. Same thing for any instruments you send. --- ***That is all according to our current understanding*** and much of it is hypothetical. That understanding has changed in the last few decades due to the "discovery" of [Dark Energy](https://en.wikipedia.org/wiki/Dark_energy) and [Dark Matter](https://en.wikipedia.org/wiki/Dark_matter) which make up about 95% of the energy in the universe. Dark Matter we're sure exists, we can see its gravitational effects, but we don't know what it is, but we do have some candidates. On the other hand, Dark Energy we have no idea what it might be. "Dark Energy" is really a placeholder for "the universe is expanding too fast and we don't know why". In reality the answer is right now we're not confident about what the distant universe will look like because ***we don't know what about 95% of the universe is***. ]
[Question] [ If a future Mars colony declared war on the Earth, would asteroid manipulation be a feasible option as an effective weapon against the Earth from a Mars colony? How would this be accomplished? Are there enough asteroids close enough to Mars that current/future rocket technology could steer asteroids towards the Earth - before the Earth could respond with an effective countermeasure? [Answer] I've taken the liberty to provide a slightly more general answer. It also answers your question along the way: **Early Stage Colonies** (*Mars population <50,000*) would be incredibly dependent on Earth, and therefore could not afford to risk ending the supply of cargo from Earth. The industrial chains leading to the production of advanced electronics and machinery would likely remain for a long time outside the reach of a colony. Mars would still be under more or less direct Earth control. *Asteroid attack chance: N/A, far beyond colonist capabilities. Probably no orbital access.* **Late Early Stage** (*50k < Mars population < 1m*) With increasing population, limits on the Earth's Mission Control's capacity to micromanage the affairs of the colonists would likely become apparent. Expect shortages in supply, Martian radicals agitating for independence, extensive mining, the first locally built nuclear reactors, early industrial plants and the first massive infrastructure projects (such as space elevators and giant domes, in the dozen km radius range). At this stage the Martian colonists are most likely to rebel, and most likely to be crushed. Lack of adequate industrial and space infrastructure would likely mean limited orbital capacity, limited manufacturing ability, and limited force-projection capability. Their fragile, easily depressurized habitats are a further handicap. *This is likely where the asteroid attack attempt would occur. **The asteroid has near zero chance of damaging Earth**, of course, since Earth has a larger nuclear arsenal, a larger space fleet, early warning due to distances and superior intelligence networks, and the manufacturing capability to respond effectively to telegraphed threats of this nature (with months to prepare, countermeasures would be developed and implemented)* **Mature Colony** With a population approaching *10 million*, a mature Martian colony would be completely unmanageable from Earth due to the sheer size and complexity of the Martian economy. Since Mars has a permanent labor deficit, the degree of robotization, AI-control and labor-saving technologies in general will be unimaginable by Earth standards, where with 10 billion humans, labor will remain relatively cheap for the foreseeable future. This will have likely given the Martians an immense technological edge in the relevant fields, while the 'frontier' environment will have engendered an openness to daring projects not seen on the Homeworld since the closing of the American West. ***Martian per capita GDP is similar to that of Switzerland, and growing at a rate of 40% per earth-year***, a rate unimaginable on the NIMBY Earth. Slowly, the "Martian Burden" as Earth-politicians will have called the immense investments required to sustain the Martian project in its Early decades, will gradually dwindle, as more and more, the technology flows become reversed, and Martian businessmen and entrepreneurs share of total new Intellectual Property approaches 5%, a 50-fold over-representation of the Martians. Their wealth and influence growing, the Martians achieve through economic strength what their rebellious parents could not by force of arms: self-representation, and a seat in the highest decision-making councils. *Asteroid attack success chance: **High**. Orbital capability is in place, secure communications and counter-intelligence probably in place. However, use is unlikely since in a vast majority of conceivable scenarios sovereignty would have been devolved to the Martians at this point, and Earth still holds a 500:1 industrial advantage* **Homeworld** With Martian population *stable around 40 million*, a population density around 0.3 Martians/sq.km, Martians decide by a slim margin to limit any further colonization by the disease-infested short people that swarm the Earth, with the occasional exception made for outstanding scientists working at Earth-branches of the major Martian corporations. Earth's opinion on the matter is irrelevant, since the Martians have a significant technological lead, a near-complete domination in terms of advanced ship technology, and own a majority of the solar space fleets, Asteroid belt mining stations and all three major space elevators on Earth. Earth is engulfed in a dark age due to massive planetary unrest by hyper-conservative Hindutva, Junzi, Quiverful, Mormon, Wahhabi and Hassidic fundamentalists that comprise nearly half of the population, and can spare little attention to distant space concerns. *Asteroid attack success chance: **Overwhelming**. Martians and their Asteroid belt colonies dominate the solar system, with a massive space infrastructure lead on the still-divided Earth nations. **Would be considered a low-tech solution, as Martian 'Mining' ships at this stage have mass accelerators that can dispatch 1-10 ton projectiles at a significant fractional $c$**. Moreover, while Earth's economy is still over a dozen times larger, Martian GDP per capita is about 30 times larger. An attack would be pointless. More likely to send humanitarian assistance.* [Answer] The problem is not so much a lack of rocks, as there are plenty all over the place, but their location and the enormous distances involved. This would not be a surprise attack. Presuming the technology to develop a self-sustaining colony on Mars of any significant size to become its own independent polity and engage in warfare with Earth, the technology exists to detect and shoot down (or just redirect) incoming rocks with plenty of warning. A far better and more likely first strike would be initiating a Kessler syndrome. Using very small rocks, small enough to not be easily spotted (or would be dismissed as no danger), but in very large numbers. This scattershot of rocks timed to go into orbits likely to strike satellites could cause a cascade of debris eventually destroying anything in orbit and denying access to/from the planet. If significant enough, you might then reduce the ability of the Earth to launch sufficient munitions to destroy/deflect the much larger rocks which could actually do damage to the surface. They would probably see the rocks coming for weeks or even months, but couldn't do much about it. [Answer] One thing to point out is that Mars has two asteroids right nearby: [its moons](https://en.wikipedia.org/wiki/Moons_of_Mars), Deimos and Phobos. They're both rather small - many times smaller than Earth's Moon - and so are thought to be captured asteroids. Here are some of their characteristics: * **[Phobos](https://en.wikipedia.org/wiki/Phobos_(moon)):** Mass: $1.0659 \times 10^{16} \text{ kg}$, semi-major axis: $9,377,000 \text{ m}$, size: $27 \times 21.6 \times 18.8 \text{ km}$ * **[Deimos](https://en.wikipedia.org/wiki/Deimos_(moon)):** Mass: $1.4762 \times 10^{15} \text{ kg}$, semi-major axis: $23,460,000 \text{ m}$, size: $10 \times 12 \times 16 \text{ km}$ Those are *puny*! Well, compared to *our* Moon. To get one of them out of Mars' orbit, you'd need to move it to [escape velocity](https://en.wikipedia.org/wiki/Escape_velocity): $$v= \sqrt{ \frac{2GM}{r}}$$ where $M$ is the [mass of Mars](https://en.wikipedia.org/wiki/Mars) and $r$ is the approximate radius of the body's orbit. Let's try it with Phobos: $$v= \sqrt{ \frac{2 \times 6.673 \times 10^{-11} \times 6.4185 \times 10^{23}}{9.377 \times 10^6}}=3022.46 \text{ m/s}$$ So it has a kinetic energy of $$KE=\frac{1}{2}m\_{\text{Phobos}}v^2=4.86863 \times 10^{22} \text{ Joules}$$ How are you going to give it that much energy? The [Tsiolkovsky rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) of a rocket gives us a good idea of how much oomph needs to be put into this. The formula is $$\Delta v=v\_e \ln \frac{m\_0}{m\_f}$$ Phobos is already moving, at a speed of $$v=\frac{2 \pi r}{t}=\frac{2 \pi 9,377,000}{27552}=2138.41$$ $\Delta v=3022.46-2138.41=884.052$. If all the propellant is used up, $m\_f=m\_{\text{Phobos}}$ and $m\_0=m\_{\text{Phobos}}+m\_{\text{fuel}}$. So $$884.052=v\_e \ln \left( \frac{m\_{\text{Phobos}}+M\_{\text{fuel}}}{m\_{\text{Phobos}}} \right)$$ Let's say that the rocket uses the [Variable Specific Impulse Magnetoplasma Rocket (VASIMR)](https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket), with $v\_e=120,000$ (at the best-case scenario). So we solve for $m\_{\text{fuel}}$: $$\frac{884.052}{v\_e}= \ln \left( 1+\frac{m\_{\text{fuel}}}{m\_{\text{Phobos}}} \right)$$ $$\exp \left[\frac{884.052}{v\_e} \right]=1+\frac{m\_{\text{fuel}}}{m\_{\text{Phobos}}}$$ $$m\_{\text{fuel}}=m\_{\text{Phobos}} \left(\exp \left[\frac{884.052}{v\_e} \right] -1\right) \approx 1.0659 \times 10^{16} \left(\exp \left[\frac{884.052}{120000} \right] -1 \right) \approx 7.88159 \times 10^{13} \text{ kg}$$ That's not too easy, to say the least. By comparison, the [N-1](https://en.wikipedia.org/wiki/N1_(rocket)), possibly the most powerful rocket of all time, had a mass of $2.735 \times 10^6$ kilograms - with all its parts! Above, we didn't even *count* the mass of the rockets needed. This would not be such a good idea. --- If you're looking for other relatively-easy choices, there are about seven or so [Trojan asteroids](https://en.wikipedia.org/wiki/Mars_trojan) in Mars' orbit. They're equally far away, though, and they don't have any advantages over choosing Deimos or Phobos. --- PhilFrost brought up an interesting point - going to a Near-Earth asteroid. There are a bunch of issues with that: * It's a *Martian* colony. You have to get to the asteroid and back. This is a *lot* easier when going to Deimos o Phobos than a Near-Earth asteroid. The journey changes from about 16 months - optimistically - to, say, a week. The time for assembling the rockets for the asteroid will take the same in both scenarios - but again, you would have to lug a big honkin' rocket to the asteroid. That's *way* easier when going to one of the moons. * You only get one shot with a Near-Earth asteroid. It might go near where you want it again, but not or a while. On the other hand, Deimos and Phobos have really short periods. Earth will have moved in the meantime, but not a significant amount. * The moons of mars have stable orbits; a Near-Earth asteroid may not. In other words, you'll know the orbital parameters of Deimos or Phobos far better than a Near-Earth asteroid. So I'll stick with Deimos and Phobos, thank you very much. [Answer] From orbital mechanics, we know that the speed of an orbit in elliptical orbit at periapsis (closest approach) and apoapsis (furthest approach) is: $$ v\_\text{ap} = \sqrt{\frac{2\mu~r\_\text{per}}{r\_\text{ap}(r\_\text{per}+r\_\text{ap})}} \\ v\_\text{per} = \sqrt{\frac{2\mu~r\_\text{ap}}{r\_\text{per}(r\_\text{per}+r\_\text{ap})}} $$ For an object in circular orbit, where $r\_\text{per}=r\_\text{ap}=a$, the speed is constant: $$ v = \sqrt{\frac{\mu}{a}} \\ $$ Let's assume that the asteroid is initially in an approximately circular orbit of radius $2.2~\text{AU}$, and we wish it to intersect Earth's orbit at a radius of $1~\text{AU}$. The initial speed of the asteroid is: $$ v = \sqrt{\frac{G~M\_\text{Sun}}{2.2~\text{AU}}} = 20.1~\text{km}/\text{s} \\ $$ And the new speed (the apoapsis speed): $$ v\_\text{ap} = \sqrt{\frac{2G~M\_\text{Sun}~1~\text{AU}}{2.2~\text{AU}(1~\text{AU}+2.2~\text{AU})}} = 15.9~\text{km}/\text{s} \\ $$ Therefore the delta-v required to move the asteroid is: $$ \Delta v=4.2~\text{km}/\text{s} $$ Trying to get enough propellant together to move this asteroid will be difficult, so let's use the asteroid itself as reaction mass with [laser ablative propulsion](http://en.wikipedia.org/wiki/Laser_propulsion#Ablative_laser_propulsion). The specific impulse is around $5000~\text{s}$, corresponding to an effective exhaust velocity of about $49~\text{km}/\text{s}$. Using the [rocket equation](http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) gives a propellant mass fraction of: $$ \zeta=1-e^{-\Delta v/v\_e}=8.2\% $$ Let's assume the mass of your asteroid is about $10^{15}~\text{kg}$, the low-end estimate of the mass of the [Chicxulub impactor](http://arxiv.org/abs/1403.6391). According to [this xkcd What-if?](http://what-if.xkcd.com/13/) it takes around $40~\text{MJ}/\text{kg}$ to vaporize rock, so the amount of energy it will take to move our asteroid is $$ 8.2\%\times 40~\text{MJ}/\text{kg}\times 10^{15}~\text{kg}=3.3\cdot 10^{21}~\text{J} $$ This is a lot of energy, it would take a 2000-kilometer reflector a month to decelerate the asteroid. Difficult, but not impossible. Let's consider a smaller asteroid, say, 100 times the mass of the Chelyabinsk meteor, $1.5\cdot 10^{9}~\text{kg}$. The required energy is now only: $$ 8.2\%\times 40~\text{MJ}/\text{kg}\times 1.5\cdot 10^{9}~\text{kg}=4.9\cdot 10^{15}~\text{J} $$ This would only require a 10 km reflector 2 days! Much more reasonable, and we can send several asteroids in a short amount of time. The solar radiation pressure on the reflector is less than $200~\text{N}$, so we don't need to worry about its orbit changing. Once you get such a large mass moving, there is basically no way to stop it. Even though we would have about a year until the asteroid reached Earth, that would just give us plenty of time to contemplate our demise. [Answer] Earth is around 2.2 AU to 3.2 AU from the asteroid belt. Lets use the minimum distance and assume the Earth is flying around the sun at a similar speed as these asteroids. 2.2 AU is around 329 Million KM. The earth moves around 30KM/Sec...lets use a range of 30KM/s to 60KM/s for these asteroids in the asteroid belt (Ceres, the largest body in the belt moves around 18km per second, so we are picking out the fast movers here). At 30km per second, it would take an asteroid around 126 days to travel from the asteroid belt to Earth (63 days for a 60km/second moving one). Ceres would take nearly 211 days at it's current speed. Space is huge and it's hard to remember the timelines when operating at this level...Earth would have a pretty long time to detect that Mars is attempting this, and even if Mars goes through and redirects the asteroid at Earth, your earthlings will see it coming for months before impact. Whether or not they can do anything about it is a different matter. [Answer] There is basically **one** propulsion method efficient enough to be used. Other methods would work but they are so much less efficient nobody would. The method is **Nuclear Pulse Propulsion** where series of relatively small directed nuclear explosions are used to push a pusher plate attached to whatever you are trying to move. This has both high specific impulse and very high energy density. The technology is relatively well studied and presumed to be already practical by its proponents. Main issues are safety and radiation. During a total war use in a weapon of mass destruction would be quite acceptable. In fiction nuclear pulse propulsion has been used to kill planetary populations with asteroids. In reality there are some engineering problems associated with building a pusher plate system that can distribute the impulse so that the asteroid would not break up. These are solvable, but the sheer scale would make them take too much time and resources for any kind of surprise to be practical. And unlike the aliens in fiction the defenders of Earth **would** know what an "orion drive" is and start taking countermeasures **right now**. On a positive side, the infrastructure built to make the asteroid not fall apart from nuclear explosions used by the drive would help the asteroid not fall apart from anything else as well. And you'd have time to fill the surface with automated defense systems. So it would be quite difficult to stop. The response to your enemy building such a weapon would probably be either an all-out-attack or if that is impractical an offer of peace. If no acceptable terms are offered, I'd presume those evil **evil EVIL** Earthlings would try to destroy so much Martian infrastructure (and population) with less powerful weapons that Mars would be unable to complete the project. So this really works better as plot device before it is even completed than it ever does as an weapon. You can just use mass drivers to bombard the planet with much better resource efficiency. Moon based mass drivers probably would be what the Earthlings would use to bombard Mars in fact. [Answer] There are a number of Mars crossing asteroids that also come close to earth. [433 Eros](http://en.wikipedia.org/wiki/433_Eros) for example. Occasionally Mars crossing NEAs pass close to the earth, a near miss. Eros came close to the earth in 2012 and we will see another near miss in 2056. It would take a small amount of delta V to nudge a near miss into an impact. It's been suggested humans would need to be on the asteroid. Not so. In fact placing a life sustaining hab on the rock would make the mission a lot more difficult. The [Keck Report](http://www.kiss.caltech.edu/study/asteroid/asteroid_final_report.pdf) for retrieving an asteroid describes a robotic vehicle driven by ion engines. The proposed Asteroid Redirect Mission is based on this report. Ion engines have great exhaust velocity. This reduces the amount of reaction mass needed to achieve a given delta V. But they also have very low thrust. This means it will take a long time to execute a burn. The larger Near Earth Asteroids are too massive to nudge in a short time. Unless the ion rockets are a non neglible fraction of the asteroid's mass, it would take years. The earthlings would probably notice and take counter measures. It might be plausible to quickly nudge a Tunguska sized asteroid to an earth impact. This would be good for wiping out a city. But if wiping out a city is the goal, the Martians could do it a whole lot more cheaply and efficiently with nuclear bombs. [Answer] Mars is at the bottom of a gravity well too, so it's kind of in the same boat as earth. Kinetic bombardment from Earths moon would be a bigger threat, as would attack from the asteroid belt. The only big rocks that Mars could easily throw would be Phobos and Deimos, but a Belter civilization could send a steady stream of big rocks and overwhelm Earth defenses. ]
[Question] [ In my story, I have a slower-than-light starship (traveling at 0.6 $c$) going to Alpha Centauri A. There are several planets around the star. The target planet is a terrestrial, habitable world orbiting at 1.2 AU (since Alpha Centauri is slightly bigger than the Sun) and a gas giant 3 times the size of Jupiter at 10-20 AU. What is the most effective way to decelerate from 0.6 $c$ 1. When arriving in the Alpha Centauri System (Pollution, fallout, etc. are allowed)? 2. When returning to the Solar System (Pollution, fallout, etc. are not allowed since we have got colonies as far as in the Oort Cloud; this means radioactive sections of the starship will most likely be detached and dropped onto Jupiter or Sun to be destroyed)? Old-school "halftime" strategy (acceleration until halfway, then brake)? Quick acceleration and then quick braking, with a coasting period in the middle? Aerobraking? Gravity assist? Please keep it hard science fiction: no wormholes and stuff; laser propulsion is used for the big part and nuclear propulsion is used for trajectory adjustment inside the Solar or Alpha Centauri system (plane change, escape/capture burns, etc...). The crew is brought to the ship in a shuttle, lands on the planet around Alpha Centauri A in a shuttle and lands on Earth in a shuttle, so the massive ship doesn't need to be aerodynamic unless it is needed for the aerobraking part. [Answer] If you use laser propulsion to get them to 0.6c, odds are that's the only realistic technology for the job. If you have a better system that works halfway between the sun and Alpha Centauri on whatever power you brought with you, then why not use that to accelerate you as well? I propose a symmetric solution. Take a small craft (the shuttle) that contains everything your settlers need to build their colony. Figure out what's needed to accelerate that to 0.6c by laser propulsion. Take the whole package (shuttle + laser), and make that your spaceship. Presumably, the majority of mass will be taken up by the laser. Build one big-ass laser in the solar system (perhaps powered by a partial Dyson sphere) and accelerate the whole thing to 0.6c. Once it gets half way, use the onboard laser to decelerate the shuttle. The rest of the craft travels in to space at 0.6c forever (no doubt bearing a plaque with naked people on it). To make things a little more economical, the first trip might just contain a load of robots and a second laser to be put into orbit around Alpha Centauri. After that's in place, you can send supplies and people back and forth more economically: using one laser to accelerate, and one to decelerate, [Answer] # Use a [solar sail](http://en.wikipedia.org/wiki/Solar_sail). [![](https://upload.wikimedia.org/wikipedia/commons/f/f7/Solarsail_msfc.jpg)](https://upload.wikimedia.org/wikipedia/commons/f/f7/Solarsail_msfc.jpg) **Advantages:** * Solar sails are lightweight(-ish) * They can be used for propulsion * According to [Dandouros et al.](http://www.u3p.net/projets/doc/HoustonU3P.pdf), solar sails built with technology in the near future could easily travel to a nearby star system in 60 years, reaching a top speed of $0.16 c$. * You might want to use a solar sail merely for braking, so it's good that solar sails are low-mass (see [this article](http://science.howstuffworks.com/solar-sail2.htm), especially the part about the material called CP-1) and can be folded up. For the calculations, an interesting reference is [Solar sail thrust calculation](https://space.stackexchange.com/questions/4587/solar-sail-thrust-calculation): > > In *Space Mission Engineering: The new SMAD*, page 555, section 18.7.2, the following thrust formula is given for a solar sail: > $$F=\frac{2RSA}{c}\sin^2\theta=9.113\times10^{-6}\frac{RA}{D^2}\sin^2\theta$$ > Where, $F$ is the thrust; $R$ is the fraction of incident light; $D$ is the distance from the Sun in astronomical units; $S$ the solar flux in $W/m^2$; $c$ the speed of light; $A$ the sail area in $m^2$ and $\theta$ the sail tilt angle. > > > If we set $\theta=\frac{\pi}{2}\text{ radians}$, then we find $$F=9.113\times10^{-6}\frac{RA}{D^2}\tag{1}$$ If we're being optimistic, and saying that $R\approx 0.5$, then $$W(s)=\int\_{s\_0}^s F\cdot dD=\int\_{s\_0}^s 9.113\times10^{-6}\frac{A}{2D^2}dD$$ $$W(s)=-\left[9.113\times10^{-6}\frac{A}{2D}\right]\_{s\_0}^s$$ Here, $W$ is work. Be careful to also account for changes in potential energy in your calculations. Also, there should actually be a sign flip in there (i.e. the $-$ should by a $+$), but that's superficial. We can then use $$KE=\frac{1}{2}mv^2$$ to find the speed at any given distance, assuming that $S$ is constant (which it isn't - it's a function of $D$); given that $\frac{dS}{dD}\neq 0$, that must be accounted for for long-distance calculations. For more fun, use $v=\frac{dD}{dt}$ to find the time it will take the sail to go from one point to another. Since solar sails don't use fuel, there won't be any pollution or fallout from their use. They're a perfectly clean propulsion and braking technique. Also, you say you're using laser propulsion. Perhaps you could create (hypothetically) a large group of lasers and fire them at the craft, creating additional thrust. [Answer] There are no good passive braking methods for such speeds that don't smash the mission. The key factor is that maximum mission deceleration is limited to fairly low values, which means a large braking distance. **Solar sails**. Using the notation of HDE-226868's answer, the braking force is $F\simeq10^{-5}\frac{N\cdot a.u.^2}{m^2}A/D^2$. It is obvious that mission deceleration will be greatest at the minimum distance: $Mg\_{max}\simeq10^{-5}\frac{N\cdot a.u.^2}{m^2}A/D\_{min}^2$, where $M$ is the mission mass and $V$ will be the mission velocity. The work of the braking force, braking from infinity, will equal the mission's kinetic energy at infinity:$MV^2\simeq10^{-5}\frac{N\cdot a.u.^2}{m^2}A/D\_{min}$ (the term corresponding to maximum distance vanishes). Dividing these two equations, we can obtain the relation $g\_{max}D\_{min}\simeq V^2$. It holds for any solar sail regardless of efficiency, material, target star &c. For interstellar but not relativistic speeds, let $V=\beta c$, then $D\_{min}\simeq\beta^2\frac{c^2}{g}\frac{g}{g\_{max}}\simeq10^5\,a.u.\beta^2\frac{g}{g\_{max}}$ where $g$ is Earth gravity. Substituting this back into the mission deceleration equation, we see that the area density of the sail is inversely proportional to the fourth power of mission velocity: $M/A\simeq10^{-16}\,kg\,m^{-2}\frac{g\_{max}}{g}\beta^{-4}$. If the mission is carrying something squishy like humans, $g\_{max}$ must be on the order of $g$. Assuming a mission velocity marginally attainable with known technology $\beta=0.1$, our braking sail must weigh at most $10^{-12}\,kg\,m^{-2}$. This is quite beyond the capacity of any known reflective material. (For comparison, a one-atom-thick sheet of aluminium would be around $10^{-7}\,kg\,m^{-2}$.) A fully solid-state probe could, perhaps, sustain decelerations as high as $1000g$, but the sail would need to sustain them as well. Solar sails aren't likely to be useful for braking an interstellar mission. **Braking on interplanetary medium**. Unless one is traveling to a young planetary system full of dust (which, *ipso facto*, will have no useful planets), IPM seems to be only dense enough to be a nuisance and many orders of magnitude away from being useful for braking a mission traveling at interstellar velocity. If we assume that IPM material simply accretes to the mission, the braking force $Mg\_{max}=\rho SV^2$ where $\rho$ is IPM density and $S$ is the cross-section of the mission vehicle. Mean IPM density in the vicinity of Earth is on the order of $10^{-19}\,kg\,m^{-3}$[[1](https://link.springer.com/chapter/10.1007%2F978-1-4419-8694-8_5)], and it falls off with distance from the primary as $r^{-1.3}$[[2](http://web.archive.org/web/19980505002742/http://astrobiology.arc.nasa.gov:80/workshops/zodiac/backman/backman.txt)]. For given $V$ and $g\_{max}$, mission vehicle must have $M/S\lesssim\rho V^2/g\_{max}$. The latter fraction is just the braking distance: $D\_{brake}\sim V^2/g\_{max}$, so $M/S\lesssim\rho D\_{brake}$. Using again $g\_{max}=g$ and $\beta=0.1$, $D\_{brake}\sim10^{14}m$ and $M/S\lesssim10^{-6}\,kg\,m^{-2}$. This is much less flimsy than the solar sail, above, needs to be. However, the braking distance ($600\,a.u.$ in our case) is much larger than the effective radius within which IPM is sufficiently dense. If hypervelocity impacts of IPM particles produce explosions and eject material, the braking force seems to be enhanced by a factor of $\sim\frac{v\_e}{L}V$, where $v\_e$ is the exhaust velocity of ejected material and $L$ is the specific heat of sublimation of the materials involved. For $\beta=0.1$ and $v\_e\sim 3\,km\,s^{-1}$ characteristic of chemical explosions, this factor is on the order $10^2$ and the mission can be heavier, $M/S\lesssim10^{-4}\,kg\,m^{-2}$ (though it must now withstand the explosions, a daunting prospect). Nevertheless, this does not remove the tyranny of braking distance and probably precludes the use of this braking method. **Electrodynamic braking on interplanetary magnetic field** does not appear to be effective [[3](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050215611.pdf)]. [Answer] Underused in SF is the idea of magnetic breaking. I recall reading about the math of a Bussard ramjet that it can't work because the drag is greater than the energy produced. But, instead of tweeking it as much as possible to reduce drag, turn the problem on its head: optimize it to *maximize* drag, and you have an excellent brake. I planned on using that in a story, but lost track of the notes I took at the time. [Google](https://www.google.com/search?q=space+travel+magnetic+breaking&ie=utf-8&oe=utf-8#q=magnetic+breaking+solar+wind) shows some suggestive topics, though. --- [Robert L. Forward](https://en.wikipedia.org/wiki/Robert_L._Forward#Rocheworld_series) wrote about lightsails. in *Flight of the Dragonfly*/*Rocheworld*, he used a [detachable ring](https://en.wikipedia.org/wiki/Rocheworld#Forward.27s_light_sail_propulsion_system) for the main part of the sail. The earth-based laser reflects off the sail and back to the craft with its much smaller piece of the sail, slowing it down. [Answer] Silly answer: [lithobraking](https://en.wikipedia.org/wiki/Lithobraking) - i.e. just crash whatever piece needs to stop into solid rock. (This would in fact be very destructive, of both the crew, their vessel, and the destination. The hot Jupiter planet might not notice an aerobraking ship, but the crew sure would.) [Answer] A simple light sail isn't going to cut it—you're not going to brake from 60%c with one. If you want a hard-science answer the only thing I see is to use your launch laser. This uses a light sail but it's powered by the laser beam rather than just sunlight, it can accelerate harder and longer than something simply using the central star for power. Now, to stop you cut off a ring of your sail—this must comprise most of the sail and most of the mass of your spacecraft. The ring flips over (or more likely simply inverts and reflects off the back side of it) and focuses its energy on the inner piece. Note that this requires incredible accuracy and is almost certainly beyond current technology. For a more detailed look at this read Robert L Forward's *Flight of the Dragonfly*. The numbers in that book are scary indeed—the launch laser is a facility around (not in orbit! It would push itself away from the planet in operation if it were) Mercury, the final focusing lens is in the outer solar system and is of planetary scale. Furthermore, his craft was only doing 20% of lightspeed. He ignored the accuracy problem of the ring focusing its energy on the decelerating spacecraft. In theory the same approach could be used again to return, discarding another ring comprising most of the remaining mass to boost for home. Stopping on the launch laser won't be a problem. The sails must be gargantuan and incredibly shiny as they will be bathed in a laser beam from hell and they can't have a cooling system, they must simply reflect off enough energy that they can radiate away whatever they absorb. I believe a much more viable approach is to send out the first craft with only robots on board. It goes considerably slower and brakes on an unboosted sail. It then proceeds to construct a laser that's a duplicate of the launching laser. You still need huge sails but you're not discarding most of the sail so it's nowhere near as big as it would have to be using the separating sail approach and you eliminate the aiming problem. The more I look at aerobrake the worse it gets. 1) The toughest aerobrake we have ever done was 47 km/sec—and at a cost of ½ of the weight of the probe being devoted to the heat shield, half of which burned away in the process. This is almost 4000× the energy. 2) I'm not competent to figure the actual deceleration involved but I can show that it's well above a million gravities. (Scaling up the Galileo probe gives a million g but it runs out of planet well before it's done. Thus the actual value must be considerably higher.) The toughest electronics we build are artillery shells—something around 1% of this energy. 3) At this kind of velocity air ceases to behave as a fluid, but rather as particles. Heat shields are based on deflecting away most of the energy that hits them but the particles won't be deflected. Your shield is going to absorb energies greater than a matter-antimatter explosion. [Answer] Best answer with currently understood technology: Only remaining reasonable method not already discussed: use H-bombs (that is, Orion drive). Despite its dry mass, the high efficiency of the Orion drive makes it unbeatable for long flights by current technology. 0.1c is attainable this way, and trying to break with a solar sail is not feasible at this speed due to inadequate force available. We can avoid most fallout problems by using a nuclear-hydrogen rocket for a planeshift burn first. This speed still makes a 40+ year flight though. Look, if you wanna get up to 0.6c and back down to 0 again you're gonna need an antimatter drive, and you're still going to need > four times your rest mass in fuel. But right now, we don't have a solution for containing that much antimatter with the fuel fractions to make this remotely reasonable. [Answer] To be blunt: the same way it accelerated. At 0.6c, there is nothing that can be used for braking but not for acceleration. [Answer] You mentioned a crew. Crews are squishy. If your ship has humans in it, it's not a good idea to submit them to accelerations much higher than Earth's gravity. I have no suggestion on propulsion methots, but the old-school "halftime" strategy as you put it is the only way to go. [Answer] I don't have much to add about drive technology -- it's already been covered. (FWIW, I favor the Orion drive at 0.1c max or antimatter tech stack.) That said, I think it's worth noting that your concerns about radiation are probably overstated. Once you get outside the earth's magnetic field, you are exposed to massive quantities of radiation from the sun. Per [space.com](http://www.space.com/21353-space-radiation-mars-mission-threat.html): > > ...the radiation dose received by an astronaut on even the shortest Earth-Mars > round trip would be about 0.66 sievert. This amount is like receiving a > whole-body CT scan every five or six days. > > > By implication, any society that can build space habitats is capable of dealing with radiation exposure. [Answer] Does the main ship even need to slow down significantly? It might be beneficial to try to keep most of the main ships momentum - instead put it into a big path around the star, using whatever thrust you have to steer inwards over a long period. Meanwhile the smaller "shuttle craft" has detached from it, and its this little craft that has to then slow down. While your still stuck with the prospect of needing to slow down from 0.6C, it should be significantly easier to do with the (presumably much smaller) mass of the little craft. While its never "easy" slowing down from high speeds, the smaller the mass the less energy it will take. You then either have the big ship slow down over a (much much longer) period using sails or a ion-drive, or try to get that little craft at least briefly upto 0.6C itself to rejoin its main craft for the trip back. (the main craft having never slowed down much at all). ]
[Question] [ Inspired by Cort Ammon wonderfully detailed answer here: [How to prevent tiny mistake in 'programmable language' magic spell causing horrible disasters](https://worldbuilding.stackexchange.com/questions/31774/how-to-prevent-tiny-mistake-in-programmable-language-magic-spell-causing-horri), and my desire to go out of my way to invalidate large portions of his wonderful answer (sorry Cort!). The premise of the world is that magic is something that can be programmed. Put together words or symbols with predefined meaning into spells, provide power to the spells, and the result is whatever the spell is programmed to do, exactly as written. Magic is not (entirely) about raw power, but instead ability to program intelligently to write more complex programs. Cort took this to the logical conclusion in his answer, treating magic entirely like a program and speaking in terms identical to Software Engineering, with the obvious parallels of writing a spell checker (I'm punny!) and even magical VMs for testing, amongst other examples. This *is* the logical output of a world where anything can be programmed. However, the world that would result from this approach is a far cry from the traditional 'feel' of most fantasy worlds, once you have the power of computer-level programming and a proper software engineering techniques you have exponential growth to a world as advanced or more so then our own. I want a world that is somewhat closer to 'traditional' fantasy, with technology no greater then Renaissance era and, while magic can obviously automate some aspects of the world, I don't want magical replacements for every technology we have. Most importantly I don't want magic computers or the exponential increase in magic that would come from spells reaching the level of discipline, and more importantly programmatic support, of magical computers. Modern Software engineering use what I'll call meta-programming, for lack of a better term, to create software who's sole purpose is to enable the production of better software. This includes things like building reusable modules and larger software frameworks (or even entirely new languages); but also includes indirect software support like use of IDEs to support software development, static analysis and unit testing tools for validating software, code repositories, or even internet and sites like stack overflow. I want to mostly forbid, or greatly limit, the ability to do this sort of 'meta-programming' due to it's allowing exponential growth as every program builds on the power of the last. Thus I'm looking for a way to keep the core concept, that magic can be programmed and good magicians are good programers, but without exponential magical growth or 'meta-programming' taking to it's logical extreme. I'm assuming a world where magic is not a brand new idea that has yet to be fully realized; it has been around for at least a century and has been taught and learned without 'meta-programming' proving a logical next step. Answers along the lines of "people just haven't thought to try meta-programming" are allowed, *only if* you can justify why a field with smart people striving to increase it's potential wouldn't realize the implication of what they can do; not just presume their too ignorant. I could think of two potential avenues for approaching limiting of meta-programming, but can't quite figure out a proper implementation of the ideas. 1. Prevent the magic from being Turing complete by removing some feature necessary for proper meta programing. Here the problem is making the programing magic 'full featured' enough to allow interesting spells, and sufficient complexity for skilled mages to clearly surpass lesser ones, while still making meta-programming impossible. 2. Placing a limit on the power level of the mage, limiting their ability to cast more complex spells and thus causing meta-programming to quickly grow too magically taxing on the caster to be viable; much as how we have limits on CPU and memory usage with modern computers. The difficulty here being how to define the magical 'expense' of more complex spells that have little direct impact on the world (and thus impart little energy into the world) in a way that makes sense (ideally even to non-programmers who wouldn't fully grasp concepts big-O or the expense of abstraction) and is sufficiently limiting while still allowing skilled mages to make complex and interesting programs. I'm open to any novel ideas for proper limiting of meta-programming beyond the above as well. If the ideas *also* encourage a system where skill of individual writing a program allows more powerful programs to be developed that is an added bonus. [Answer] One way is to make it so that you can't create frameworks. Corts answer was a great example of software engineering, but how would you create a framework that can be used and reused and build upon by anyone? You can't just write your code on the fabric of the universe. For instance, say I create a spell to warm my tea. I cast it and my tea is warm. In software you'd then create a function to warm any object to any temperature inside a class with other functions and it becomes a framework. But a magic spell isn't software. The closest you could get would be to have a big spell book with all the spells, and invoke each one in turn, one at a time, which is classic fantasy. One spell wouldn't invoke another spell. The closest you could come to having stuff passed around would be if you bound magic to an object, like a magic ring for instance. The object would be usable by anyone wearing it, but once bound unchangeable, and unable to trigger or affect any other spell. Lastly, the language could be a very low level language. Running on the bare metal as it where. And without the ability to make spells that call other spells you couldn't really make a high level language very easily. [Answer] So as you can tell, I've played with these concepts just a little bit =) I find them great fun because its so easy to create scenarios where you don't know what's going to happen, but that brings a sense of wonder rather than fear. I'm actually playing with this system right now, and I think it has a reasonable chance of meeting your needs. I'd love to have more people playing with it, beating on it, leveraging it, seeing what it can do. Fundamental to the way Turing machines reach their ultimate capability with Turing Completeness is the idea that the bits stored last forever. If you write a 1 to a memory address, and come back any time later, it will still read a 1, as long as you or nobody else who has access to that memory space writes a different value. What if we took that away? What if bits did not always behave like perfect little angels, holding onto our data for an eternity? What if surprises could happen? Surprises are great for a mage, but very very undesirable in the programming business, so this seems like a rather promising way to go! If you take a hard look at our computers, you will find that they are not actually Turing machines. We program them according to a model which is Turing complete, but the real machines are layered on top of physical hardware. Fuses blow, cosmic rays dash bits of data into oblivion, even the dopants which turn silicon into one of the most valuable substances on earth eventually diffuse enough to end the life of a chip (especially if you run it too hot). Turing machines are an approximate model of the real thing, and quite an optimistic model at that. We get away with treating them as Turing machines because the mean time between failures for our modern processes is quite high. 99.999% of the time, your computer acts indistinguishable from a perfect Turing machine. That last 0.001% of the time? Well, that's when you angrily hit the reset button and think about just how much work you lost! But what if the components were even more unreliable. Too low of reliability, and the only Turing style programming you are going to do is simple stuff, or small stuff. Of course, having your components always turning into useless smoke on a regular basis isn't going to the basis of much magic, so we're going to have to be more creative in what it means to be unreliable. What if every "component" of a spell had its own "personality." It generally does whatever it feels like. If you can get a good bead on what it feels like doing, you can integrate it into a spell such that it generally does what you want it to do! This is a rather foreign concept to traditional engineering, but we see it in art all the time. When it comes to musical instruments, there's "good instruments" there's "bad instruments," and then there's those beautiful artists who can make music with whatever instrument you give them, catering to the instrument's strengths. Mages making spells would have to have some ability to create components, just like imbuing a spell with magic in the first place. Clearly they would want some level of control over the personality of each component they create, but each component would certainly have its own individual spark. A novice may cram a bunch of components which they believe will work together, but an expert will listen to each component softly, listening to its whispers and adapting the spell to suit. Now any engineer will look at this, and see the opportunity to abuse the Central Limit Theorem to minimize the effects of personality on their final product. As long as the effects of all of the personalities work out to about average, the spell will work. To tear this away from the engineering and programming minds once again, we're going to give these components two abilities. * Components can "talk" to each other, in any way they see fit. You can make it harder for them to communicate by putting stuff in the way, but you can never prevent it. If you give one component of a spell a pretty posh deal, and shaft another, you might regret your decision when they start comparing notes. * Components can cast magic of their own, creating new components. Obviously they're limited by the energy available to them, but the personality of the new component is all up to them! The former rule makes it clear that you're never going to "control" the spell statistically. You're going to have to work with the spell, negotiating with it, bartering with it, until it agrees to do your bidding. The latter makes that even more extreme, because the spell can actually change meanings completely while you're not looking at it! (This is also really close to the "grey goo" concept of runaway AIs that can replicate) Now how do we make sense of all of these components? There's actually several approaches, which may form several different fields of magic. One is testing. You stamp out a billion small components, and then test each to determine if they are a match for the personality you need. This gives you great precision in your spell, but is extremely wasteful (more on waste later). Another approach is to carefully listen to each component, and find it the best place possible. This creates spells of extraordinary power, but they are very tedious to construct. A third approach, we borrow from Mickey: [![Mickey!](https://i.stack.imgur.com/on9nbm.jpg)](https://i.stack.imgur.com/on9nbm.jpg) You mentioned wanting to limit meta-programming; this system embraces it. What if each component acted like a spell, itself. It was simply casting whatever effects its personality wanted to do. This means that components are not lying in wait, ready for you to pull the trigger. They're doing their own thing. And that means, we can put them to use! If we can encourage a few well-minded components to be sheep dogs of sorts, they can keep the rest of the components in mind as they jabber amongst each other and spawn new progeny. These components may be trained (by the mage) to encourage the others to want to do productive things, working with their personality like we do when teaching or tutoring. This is the dreaded meta-programming you mentioned, but its wings have been clipped. Instead of getting to rely on perfect provable automata, the wizard has to depend on a bunch of spells with personality to help him or her out. Needless to say, the art of stacking this meta-programming chain arbitrarily deep would be true art indeed, rather than a simple provable eventuality. Fundamental to all of this is the idea that the components have some value. If I'm programming, and I determine I no longer need an integer, it is summarily sacked. In fact, I care so little for it that I let my compiler decide when and where to reuse its memory for another purpose... I don't even think about it. However, if these components have some intrinsic value, it makes sense to protect them, and reuse them after the spell is over. However, this leads to the question of where does the initial components come from, since something of value had to go into them. I suggest a system of offering. You offer something of value to {whatever}, and you are given an initial component in return. You can then teach this component to help you create new components, or offer something more to {whatever}. You never know what you get, but the general trend is "the more you sacrifice, the more you are given." This gives each component value. You can also have an alternate construction, where you offer nothing, and accept whatever component you are given. Schools could grow up around how to care for these components that come from nothing, to give them value that nobody else could see. All of these rules lead to two neat patterns that I find fascinating for World Building purposes. First is a set of archetypes for working with components: * The technology route - use lots of small cheap components, test them out, determine which ones meet your needs. Gets you good results quickly, but is wasteful of material. * The noble route - use very expensive components to accomplish everything. Gets you good results quickly, but you may have to sacrifice a great deal of wealth for them. * The artist route - use few components, each carefully listened to and whispered to. Gets you good results with very little waste, but its terribly slow. * The delegation route (Mickey!) - use components to work with other components for you. This permits massively parallel training of components that permits good results with little waste very quickly. It, itself, has two extremes, from which you can mix and mingle to your leisure: + The light side - encouraging components to work with you, listening to them, and adapting based on their wants and needs. This allows for theoretically unlimited capabilities, but you don't have full control over the situation. Done wrong, your components may break away from you and grow on their own, or you yourself may become a slave to them. + The dark side - ensuring components work for you by fear. As long as every component is afraid of you exerting enough spell casting power to wipe that component out, they are kept in line. This also has theoretically unlimited capabilities, but you must always fear a rebellion yourself. Your construct may turn on you with its full force, and you may not have enough power to wipe it all out at once. The second neat thing is a new reading on the concept of a spell scroll. A spell scroll could be, as always, a bunch of magical components imbued onto a sheet of paper with a trigger to set them off. However, it could also be a non-magical sheet of paper with directions that permit a "delegation route" mage to let a component cast the spell for him/her. In this case, the scroll is not magical, but its more like a set of guidelines to help the caster make their own magic. In fact, one of these scrolls might even be the basis for the generation of a component without a sacrifice, bringing a new way of magic to a old world stuck in its ways. In my playing with this system, I have found it allows intelligent individuals to construct rather marvelous things. However, I have found that, even more, it allows *wise* individuals to construct things nobody ever thought could be constructed. Wisdom reigns supreme in this system, not intellect. [Answer] How about limiting the "memory" of the magic users? A better magic user can memorise bigger programs, so is capable of more complex magic. Or you could have a "clock speed", whereby a more capable magic user can run through steps more quickly, increasing the speed in which they can cast, and thereby allowing them to do more in a given time? --- Going back to the idea of Turing completeness, though, I'm borrowing heavily from an answer on [Programming Stack Exchange](https://softwareengineering.stackexchange.com/questions/132385/what-makes-a-language-turing-complete): > > In general, for an imperative language to be Turing-complete, it needs: > > > * A form of conditional repetition or conditional jump > * A way to read and write some form of storage > > > A jump could include something like a function definition, or a "subspell", which can be referred to multiple times - if I want to turn a bag of leaves into gold coins, I effectively run the "leaf to gold" subspell in a loop, with the end condition of "bag contains no leaves". There is no particular difference between changing one leaf to gold and changing 1 million leaves to gold in this case - there might be a time implication (which the clock speed suggestion addresses), but it's not memory bound really - there is no need to remember how many times the loop has run, just that you keep running it whilst there are still leaves in the bag. The storage requirement allows for a more abstract end condition, so is easier to get rid of. For the bag of leaves to gold, the end condition is fixed, and easy to check (well, unless you get too much gold). For something like "give every person in the kingdom one gold coin, when they visit the fountain in the square", you need a kind of memory. Has this person previously had a gold coin? You can't easily check this condition based on any other source, so you need the memory to be implemented in some way to fully automate this spell. Luckily, removing the possibility of memory limits the kind of spell you can do in almost exactly the way you want. If there is no way to store the current state of the spell, you are limited in the possibilities of meta programming, since you can't stop and debug code. You are limited effectively to input testing: I provide a bag with 1 leaf, and see what happens. What if I provide 1 stone instead? What about 10 leaves? What about 1 gold coin? There isn't the concept of a program state - either it has been run, or it has not been run, or it is in progress, and you can limit that by affecting the input (reaching into the bag and pulling out leaves). [Answer] --- ## Original Answer > > I'm looking for a way to keep the core concept, that magic can be programmed and good magicians are good programers, but without exponential magical growth or 'meta-programming' taking to it's logical extreme. > > > The reason why there wouldn't be exponential growth is because high level magic has a cost. Consider the case software, the only reason why we can run complex high level software is because hardware improved... picture running Windows 7 on a 80's machine. You get the idea. In the case of magic... sure you can create complex abstractions, but unlike computers the CPU models are not increasingly faster. Magic runs at the universe at the speed of magic (whatever that is), and it doesn't double each 18 months... so each abstraction brings an additional cost in time (and any other cost magic has). --- > > Prevent the magic from being Turing complete by removing some feature > necessary for proper meta programing. Here the problem is making the > programing magic 'full featured' enough to allow interesting spells, > and sufficient complexity for skilled mages to clearly surpass lesser > ones, while still making meta-programming impossible. > > > It is understood that the better the understanding of the nature of the universe is, the better the mage. Because (as is the case with software) an user that understands what is happening at a lower level will be able to better take advantage of the tool. As per making it not turin complete... what I would do is force the magic to be cosntant. Sure you say it is created like a spell that is wrote is some langague. It makes sense to me that the spell doesn't take parameters, and doesn't have an internal memory. Instead magic use the universe for storage. So it has to move stuff in the world to store information, and retrieve information from it. This mean that the use of "memory" requires energy, and by whatever means this is done, other magic active at the same time could mess with it... meaning that memory is not a sacred place and information can be lost or corrupted. Using magic to protect the storage location for the spell will have an additional cost too - and it is probably something unskilled users don't do. [Please see extended answer below, for another idea] --- > > Placing a limit on the power level of the mage, limiting their ability > to cast more complex spells and thus causing meta-programming to > quickly grow too magically taxing on the caster to be viable; much as > how we have limits on CPU and memory usage with modern computers. The > difficulty here being how to define the magical 'expense' of more > complex spells that have little direct impact on the world (and thus > impart little energy into the world) in a way that makes sense > (ideally even to non-programmers who wouldn't fully grasp concepts > big-O or the expense of abstraction) and is sufficiently limiting > while still allowing skilled mages to make complex and interesting > programs. > > > The prefered storage location for magic variables could be the memory - as in the brain - of the caster. This means that accesing the memory of a person via magic is doable, protecting own memory from intruders is a must for mages, and using an spell that spawns a large data structure - in addition of the energy cost for the extra neuron synapses - will have an impact of the mage concentration [and perhaps sanity]. --- ## Extender answer **How to prevent tiny mistake in 'programmable language' magic spell causing horrible disasters** Since we are considering a world with a magic that uses memory that could be corrupted... the concern of [the old question](https://worldbuilding.stackexchange.com/questions/31774/how-to-prevent-tiny-mistake-in-programmable-language-magic-spell-causing-horri) is relevant. A solution is to have students create their magic using a higher level language, that has already incorporated limitations and controls, that makes it both predictible (to a degree) and easy to use. So, elements used in this language are not the most basic ones. Instead they are made by expert users and invoked by the lesser ones. Even tho, it has been mentioned that there is (as currently stated) no sandbox or virtual machine for magic, some preventions could be taken for safe experimentation. Also, the ones that are allowed to know the low level language should be selected and trained to be responsible, careful and skilled enough. Sure, there is no perfect security... and some tragedies may lie in the past, but nothing from which they can't learn and improve upon. --- Also, if we go for the idea of a high level language it could have limitations built in. It could be not turing complete intentionally, as a way to prevent new users from doing dangerous things. For instance, the high level langauge could include a fail safe that will shorthand any long running loop, that means that no magic that uses the high level language will run for an undefined period of time. --- Addendum: Extending on the idea of having no internal memory. This will make it harder for magic to write magic, as it will need the meidum to do it (be it a person, or some writing material). As per, materializing where to write the spell, you should consider what goes into materialization. Are you taking protons from some atoms in the air and moving them to others to create heavier materials? Sounds expensive. How about teleportation? Even if magic allows it, didn't it cause a sudden pressure difference? And besides, it moved some mass across a certain distance in no time, that's infinite energy. [Answer] So far, all of these answers have been about limiting computability and meta-programming as a solution to your problem. Your main issue with software engineering seems to be that magic will become too "overpowered". > > However, the world that would result from this approach is a far cry > from the traditional 'feel' of most fantasy worlds, once you have the > power of computer-level programming and a proper software engineering > techniques you have exponential growth to a world as advanced or more > so then our own. > > > However, removing turing completeness from your 'magic language' is perhaps not the only way and certainly not the easiest way to achieve this effect. For a real world computer, there is another thing besides raw computing power that determine what it can and cannot do: I/O. from [this answer about turing completeness](https://softwareengineering.stackexchange.com/questions/132385/what-makes-a-language-turing-complete): > > Strictly speaking, I/O is not required for Turing-completeness; TC > only asserts that a language can compute the function you want, not > that it can show you the result. In practice, every useful language > has a way of interacting with the world somehow. > > > So my solution would be: # Make your "magic computer system" have a limited set of I/O operations. this makes it really difficult to achieve something great. **Clearly define the interface your language has to the outside world.** Perhaps I/O operations would only be possible that make some change to a single particle, such as moving or transforming a molecule or a grain of sand, and doing lots of these operations would be expensive. It could cost a lot of time, materials, energy, some kind of 'mana points' or other resource which is costly. In short, you could consider not limiting the possibilities of your magic system in software land, but instead limit the possibilities of your 'hardware'. Since the 'hardware' is the the way your programs affect the real world, and how it works is completely determined by you, you don't need to have some kind of stagnation in the technological advancement in the "software industry". This way you dont have to impose a limit on the ingenuity of the mages in your world, but can still conveniently limit their capability in such a way to fit into your story. [Answer] There are already two inherent limits to "meta-magic" in the sense you use it, which you've also already touched on 1. Magic messes with reality. It can't be sandboxed. 2. "meta-programming" generally comes with a performance cost And then you also need to nail down what exactly the result of a "syntax error" would be ### Sandboxing Most of the "meta-programming" in actual software engineering relies on some assumptions * "meta" products (frameworks, libraries, virtual machines, etc) are reliable * they can be developed and tested independently of anything they might be used with (e.g. you can write a library that is linked to other code, and operates using callback functions, without knowing about or actually having those callback functions present, although you would need a stub function for testing) * testing during production of "meta" products is safe, and relatively inexpensive (because it can be sandboxed), and the test stubs might be harmless (but that assumes the stubs have been tested as safe too ;) ) The reason we have stable, usable virtual machines is that we started with a level physical isolation from the beginning. Mucking around trying to develop the virtualizable chips and the virtualization software would break a single physical machine at a time, with no risk to the "caster's" life. You can't create a virtual machine with magic, because you're already living inside the host machine, a.k.a. reality. As far as reusable code components go, you already have that sort of stuff in more traditional magic systems, in the form of spell scrolls or otherwise repeatable and shareable magical effects. You could possibly build a spell engineering room, with walls, ceiling and floor imbued with magic dampening barriers. Inside this room you could test your magic frame work, but you'd still be inside the room with your magic, and it could kill you, making development extremely risky. And development of meta-magic \*extremely\*\* dangerous. Testing a change to a magic framework for spatial manipulation/placement/targeting of your spell, and accidentally have an infinite loop with your testing spell to move a pebble. You **know** your move pebble spell is safe, but the infinite loop in the framework makes the pebble zip back and forth at increasingly faster speeds. Now it's a speeding bullet in a ricochet chamber. You could try to develop a library of spells (functions) that get combined (linked) with other magic, but this assumes magic is allowed to exist in partial form, so it can later be combined. Of this would always be possible if there is a theoretical representation of magic available, i.e. the equivalent of source code, where the actual magic is machine code, and the compiler/linker is the caster. But, even with a theoretical representation, the framework/library would still need testing, which requires execution. How would you know your framework for parallelizing a spell works, if the spell being parallelized is a do-nothing stub. Even if all the spell does is create some sparkles, that would require energy, and what if there's a bug in your framework that allows runaway threads... methinks, dead mage, or burnt out mage, or similar. As far as static analysis tools are concerned, most of those rely reproducing functioning parts of the compiler (lexer, parser, etc). In code, this is a "simple" case of reading and processing text strings. But if the compiler is human (or some other living being) that means reproducing a substantial part of the consciousness of said living being. The main distinction here is that in real life software development, the physical machines executing your code are inherently symbolic in nature. You're not messing around with electrical currents and different voltages, you're dealing with bits in memory. The hardware does a significant amount of abstraction for you. With magic, the same isn't true. The magic to read symbols for a written page would have to at some point distinguish the ink from the paper (either via visual recognition, or atomic analysis), translate that into text, etc before any static analysis could be performed. It all depends on the primitives of the "magic language". ### Performance costs of frameworks/libraries Using frameworks, libraries, virtual machines, containers, etc all carry a performance cost in software development. Sure, sometimes the cost is negligible, truly. But most of the time, we consider the cost negligible because the underlying hardware has become fast enough that those costs are imperceptible (or acceptable compared to the gains in actual development time). Reality, the physical hardware of the magic language, doesn't get faster and doesn't obey Moore's law. Also, if casters are expected to provide the energy (either from themselves or a secondary source) then frameworks becomes doubly expensive, both it terms of spell execution time and energy costs. ### Syntax Errors are a special class of bug So, in general, the closer to the bare metal you are, the less syntax there is. Technically, you can't make a syntax error in machine code. You upload a bunch of binary into memory, execute it. There can be plenty of *other* errors when you do that, but not really syntax errors. And magic is pretty much as bare metal as you can get. There are two possibilities here 1. Syntax errors are a result of casters acting as compilers, translating between a higher level expression of a spell. A syntax error in the higher level expression could still then be handled (because the caster-compiler is intelligent) but it makes the spell more difficult to cast. It might be so bad that the spell 'crashes', being only half complete. Did you leave out a semi colon somewhere ... "ignite flame in palm; grow flame into fireball move fireball where I point"? Now your hand is engulfed in a fireball, whoops! Doing it this way would imply that magic is an interpreted language and executed on the fly, further limiting magic-assisted static analysis 2. Syntax errors actually exist, because reality has a syntax, e.g. a caster tries a spell that violates some technical law of magic, e.g. a targeting verb must have at least one operator of a particular type (point in space, area, or volume). Now if there's a spell that doesn't specify a target, reality crashes (or at least a localized portion of it crashes). I would think that if your messing with spatial targeting and relationships, and you break the syntax then physical spatial relationships start breaking down, and stuff disintegrates. The extent and vigour of such "crashes" might be related to the amount of power put into the spell initially. Another magical syntax rule might be that "life force" must be conserved, i.e. you can't just set the number, you can only add or subtract from another life force pool, i.e. transfer. To heal one person, another must sacrifice their life force (voluntarily or otherwise). If you don't specify a source of life force, then all life force in a localized area is suddenly averaged out, injuries heal by taking equal portions of life force from everyone within the radius of the crash zone. ### Summary To answer your question directly, I don't think meta-magic programming should be impossible. Assuming you disallow high level primitives and symbolic introspection of magic, it will be hard enough, dangerous enough and expensive enough as it is to not develop rapidly. I would strongly suggest that you tie execution of a spell to some cost or resource, payable by the caster, e.g. You can sit down and design/write your spell source code as long as you want, but when you cast, your life force pays per clock cycle/instruction. This means that what makes a mage truly powerful is 1. the ability to not make (or catch and correct before casting) mistakes in their source code 2. the ability to write efficient source code (they can fling more fireballs per reality clock cycle) Tying casting cost to spell efficiency is the key to keeping frameworks out of the picture, but you get to keep Turing completeness, reusable 'code' components, etc... [Answer] Software and even areas of study like symbolic logic, rely upon created "languages". The reason is that natural languages are too imprecise and inefficient for writing expressions in. Following in that vein, you could force: ## spell magic to rely upon natural languages only This would make the development of magical expressions very much more difficult than getting to use a more precise invented language. How you would explain this limitation in a believable way is up to you :) It's imprecision and "clunkiness" would limit what could be done with it pretty effectively. It also might mean that every person had the ability to "cast" a certain amount of magic. But only those that have studied for a long time would be capable of mastering the art. IMO, this would make magical spells come to resemble legal documents (and wizards the equivalent of lawyers, lol!). Pages and pages of statements which few realize all the ramifications of. [Answer] # Spells are limited to a specific rune count. If spells had to fit in a tweet, there would be a limited set of operations you could do with them and you'd basically be forced to golf every spell. Granted, there might be hundreds or thousands of different runes at your disposal, but you won't be able to do anything beyond a certain complexity simply because of length limitations. The end result would be a lot of specialized-purpose spells that make a lot of assumptions and not a lot of frameworks/libraries or customizable spells. You might be able to employ clever tricks to make every last rune count, but the most complex spell you could make would be something on the order of the original Pitfall. (Note that Pitfall wouldn't actually fit in a tweet, though it was crammed into 4KB, which is still very impressive) [Answer] If your goal is to ensure the magic isn't Turing Complete, there's two things you could omit: 1. Conditional branching. Omitting this makes anything requiring a decision impossible. An infinite loop is still a possible construct, by using unconditional jumps, but one with an abort condition is not. This would essentially limit all decision-making to being done by the caster before casting. A magical security system which lets authorised people in would not be possible with this model. You could make a spell which generates a bubble of heat around whatever it's cast on, though. 2. Storage. Omitting this results in a Finite State Machine. This pretty-much limits you to programming with regular expressions or state-machine diagrams. More useful than the former approach would be, but still limited in power. For a gaming example of a non-turing-complete programming scenario, though sci-fi themed, rather than magic, take a look at SpaceChem. The reactors you design in the game are FSMs. They have a decision-making capability in the form of a sensor object which can report the type of atom over it, but they don't have any storage. ]
[Question] [ So we all know that the majority of sea creatures use fins that move either from side to side or up and down to propel themselves. But our boats don't do that. Our boats use propellers - a rotational motion not based on sea life at all. That begs the question: how plausible is it for a sea creature to evolve to "spin" in the water as a method of movement? For example, imagine a fish that had a body containing the shape of a screw propeller (perhaps multiple screw propellers?). It would move through the water by "corkscrewing" itself forwards. # What scenario would result in this sea creature evolving, and as a bonus, how efficient is the corkscrew fish movement compared to the current method of locomotion? NOTE: Creature must be large enough to be visible to the naked eye (no microscopic organisms allowed) But if you want to say that the creature evolved from a microscopic organism that already uses said approach to movement if you can make it plausible, feel free. **EDIT for clarity:** You may assume that there are an abundance of nutrients available. Optimal growing conditions, you can even assume that this guy has no predators. Explanation for reality check tag: it says "if a concept is realistic in a given context" to which the context here is whatever it needs to be to make it happen [Answer] Symbiosis easily bypasses natures "no continous circular motion" law (i.e. nothing that requires a hub and wheel). You've a scavenger animal type thing with at least with two feet. You've a vaguely propeller shaped coral/plant, that filter feeds. The scavenger/crab/mollusc/? lives in the hollow core of the plant, gains protection (like a hermit crab). The crabs flight reflex sometimes spins the vaguely propeller shaped plant which moves them both away from predators, and faster than the scavenger could move on their own. We now have an evolutionary advantage. Fast forward a million years. You've free floating plants with extremely well designed bodies for "spinning" locomotion through the water, each with at least one (possibly a colony?) of descendants of the crabs, running like mad inside. The crabs can pop out to feed, everyone benefits with protection and locomotion for the crab, and locomotion for the plant. So now you have swarms of sea life that propel them selves through the sea by spinning like propellers. ## Update I've been thinking about this off an on. You could have several species of these evolve. I'm picturing a predator which extends its head and body out in front of the propeller part. It's many legs have evolved to fit inside the plant and spin it around. The whole assemblage is torpedo like. Eyes and mouth are forward facing like a shark, and it steers by flexing its body. [Answer] **Macro animals aren't going to do this.** Single-celled creatures can do this because they don't need to supply the rotating body component with nutrients, those come in from the surrounding medium. The [flagellum used by some bacteria](https://en.wikipedia.org/wiki/Flagellum#Bacterial) is essentially a biological rotary engine. It likely evolved from a [type three secretion system](https://en.wikipedia.org/wiki/Type_three_secretion_system), which has very similar components. ![enter image description here](https://i.stack.imgur.com/E8BiA.png) Macro scale is much harder to accomplish. Spinning parts don't exist on the macro scale. Having the entire body as the corkscrew doesn't work well because they still need some way to push to get spinning in the first place. You've probably seen octopuses doing something that looks like corkscrewing through the water, but they use [jet-propulsion](https://en.wikipedia.org/wiki/Jet_propulsion#Jet-propelled_animals) to get themselves going and sometimes spin while doing it. To have a body part that spins freely is a problem. It's not well connected to the rest of the body. Blood vessels, tendons, muscles, and whatever can't be used between the main body and spinning portion. It's not more efficient to rotate for macro animals. If you look at [gymnoformes](https://en.wikipedia.org/wiki/Gymnotiformes), they are sort of (from one frame of reference) partially rotating to achieve locomotion. But rotating oneself in order to propel forward is like adding an unnecessary energy conversion step. **However**. I can imagine some small animals that might use a external component, like a shell, which they would spin to propel themselves through the water. It wouldn't be very efficient and would probably only work in calm waters. [Answer] I can't see an evolutionary path to why this would happen, but I believe that physiologically, it is possible. Consider the human arm. The ball and socket joint at the shoulder allows for full circumduction of the arm (imagine winding up and [pitching a softball](http://topsoftballdrills.com/softball-pitching-drills/) or bowling a cricket ball). If we have an underwater creature with a couple of appendages of the right shape and in the right places, and joints with the correct articulation, I don't see why it *isn't* possible. However, I don't see what the [evolutionary benefit](http://en.wikipedia.org/wiki/Rotating_locomotion_in_living_systems#Evolutionary_constraints) of this would be. This seems to be something more like a mad scientist would piece together. I don't know what the thrust of such a mechanism would be, but I can imagine the energy requirements for sustained locomotion of the Frankenfish would be quite high. ### Edit: I hate saying that something is not possible. After all, this is *worldbuilding*. So, I'll try to make a case for evolution of rotational locomotion in a macro-organism. Incidentally, the mechanism of movement is different than what I described above. As sea levels have been steadily rising and land area has been steadily decreasing, land mammals, which had previously evolved *onto land*, are now evolving back *into water*. Some animals (amphibians, reptiles) are obviously better equipped to deal with this than others. But there is one interesting case to consider: the field mouse. It started as field mice had to swim more often than they used to, from one piece of land to another. The mice that ended up surviving more often than not were the ones that were better swimmers - a trait that became [primarily determined by their tails](https://www.youtube.com/watch?v=NMc5UFVHh18). Eventually, mice ended up spending more time in water than out of water. Their physical features changed over the centuries to reflect their aquatic lifestyles: their feet shrank to reduce drag, they could hold their breath for incredible amounts of time, they had special eyelids so they could see well underwater, and their tails grew powerful as a flagellum-like appendage for movement. [Answer] An animal that lives inside of two shells, positioned end to end, each shaped like a corkscrew or propeller, could rotate the shells on their common axis to propel forward. The animal itself wouldn't need to have a rotating part, it could just have pseudopods that grip the inside of the shell and twist, like an octopus letting itself out of a jar. Imagine if the lid to this jar was propeller shaped: <https://www.youtube.com/watch?v=IvvjcQIJnLg> [Answer] I'm sorry, but the answer is 'no'. Physics and scaling are important: Flagella are quite unefficient: in order to rotate them, most of the force is applied perpendicularly to the direction of motion, and it costs work to compensate all that friction. For [Seth](https://worldbuilding.stackexchange.com/questions/15278/sea-creature-moving-via-rotational-motions/15291#15291): An evolved rat would swim, just like any other mammal, because it's way more efficient (and a minor evolutionary change, too). [I dont' know if this answers your bonus question. If I had more time I would throw you the relevant equations] So, why do bacteria use cillia and flagella instead of swimming? The answer is the [Reynolds number](http://en.wikipedia.org/wiki/Reynolds_number): a number that describes how important are inertial effects in fluids. Reynolds number depends on the size, so bacteria in water have lower Reynold number than rats in water. In other words, bacteria struggle to move in water as you would do to move in honey. Swimming strokes are symmetric if the time is reversed, and that means that no net motion is possible without inertia (Purcell called that the [Scallop theorem](http://en.wikipedia.org/wiki/Scallop_theorem)). To overcome this, bacteria use movements that are not invariant under time reversal, like rotating flagella (seen in reverse, you would see the flagellum rotating the other way). The extra energy cost is not a big deal for bacteria (they live surrounded by enough resources), but is a problem for a rat or other macroscopic beings. [Answer] Some microscopic organisms use the corkscrew approach. [Here's a page with some information and video about them.](http://www.microbiologybytes.com/video/motility.html) I don't know how practical that would be to scale up, considering the complexity of the brain, dizziness & sense of up and down, relative thickness of the material (water) they're moving through, etc. But corkscrew critters do exist. [Answer] I'll give the 'no' answer to this...the most obvious answer is locomotion techniques that involve the entire body are going to be quicker than a little prop hanging off the creature. 1. The propeller isn't a terribly efficient method of transportation. Without engines to spin these props, they don't move too fast and accelerate horribly slow...a creature with a propeller would be pretty open game in any open water. The swimming motion creates much faster acceleration. 2. Propellers were designed specifically for boats that can concentrate a huge amount of power in a small area (incredibly small area if you consider how small the prop is to the boat it's powering). I can't think of any creature that could sustain the rotations a prop would require over the time needed, nor am I aware of any creature that dedicates such a tiny portion of it's body to locomotion 3. High speed spinning prop = damaging. Props are made of strong metals and even these frequently chip. A high speed propeller on a creature would be very prone to damage and any attacks that damage it would cripple it heavily. One of those cases where I think it's quite likely feasible that it could exist, but it's so inefficient that they would easily as prey to species possessing better locomotion ]
[Question] [ In 1857, native soldiers in the Crown Jewel of the British Empire--the Indian subcontinent-- mutinied and for three days established rule of a native monarch. Eventually, British imperial might toppled this rebellion and independence remained more of a concept than reality until 90 years later. But what would have happened if this revolt had succeeded leading to the birth of a new nation in the southern Asia? How much would the world have to lose or gain by this? [Answer] In 1857, there was no such thing as India. There was a patchwork of feudal states in the subcontinent, with large chunks of land ruled directly by the British East India Company in their three Presidencies (Calcutta, Madras, and Bombay). The British 'Raj' did not start until AFTER the mutiny; the mutiny caused the British government to reorganize the territory into a proper crown colony, in large part to prevent the tax and corvee labor abuses by Company officials that caused the mutiny in the first place. So firstly, the Sepoy Mutiny was largely concentrated in the Upper Ganges valley, from Delhi to Bihar along with the adjacent Madhya Pradesh. The Bombay Presidency was barely affected; the Madras presidency was not affected at all. So even if the rebellion had 'succeeded' and the British had abandoned the Calcutta Presidency completely, the newly formed state would consist only of the Ganges Valley and parts of Madhya Pradesh. Secondly, it is important to remember that there were large states in India which were nominally independent until 1857. States such as Hyderabad, Mysore, Kashmir, and Travancore did not support the rebellion. In fact these rulers had every reason to oppose a 'nationalist' rebellion against foreign monarchical authority. India was at the time (and largely still is) a well mixed society with many different religious, linguistic, and cultural groups living in close proximity. Every ruler had many subjects of a different religion, language, and culture, and wanted to keep those people ruled. So even if the revolt 'succeeded', the previously established rulers in India had no reason to unite with the mutineers. This can be seen in the disposition of the Sikh warriors of Punjab. They had less than a decade before the Sepoy mutiny been subjugated by the British East India company. They had ruled an Empire in Punjab that had been destroyed in 1849 and brought under direct Company rule. If anyone wanted to get back at the British, it would be the Sikhs. Yet during the mutiny not one Sikh unit revolted; their hatred of the Bengali (Hindu) sepoys that had been the front line troops in the 1849 war was greater than their antipathy for the British. In conclusion, if the Sepoy mutiny had succeeded, it would had likely precipitated the dissolution of a united subcontinent into smaller, fractious warlike states. India would be more like Africa than the successful and growing democracy that we see today. [Answer] It is hard to see that this would have been a positive thing in the long run. There were some Asian monarchies that persisted fairly late (Siam and Japan's until the present day, China's until the Communist Revolution, Malaysia (a rotating federal monarchy), Korea's until 1910), and those were generally positive in bringing about national unity and providing a centralize response to colonialism. But, in each of those cases, the monarch was unifying a genuine nation state or an indigenously created federal state. In contrast, in 1857, it had been centuries since India was unified under a single monarchy, and was far from a nation-state. India was divided religiously, had a couple dozen languages, had a weak sense of national identity, and had a homegrown class of lawyers, senior civil servants, and politicians that was still very thin. A monarch is nothing without layer upon layer of well established aristocrats below him to legitimatize him and provide a foundation of elite support. A monarch without a long dynastic history that encompassed the entire sub-continent, or an aristocracy, would be hard pressed to rule. India was precocious when it came to anti-colonial revolution, but if you look at the examples of Latin American revolutions in the 19th century, and the many grants of independence in the 1960s, for example, in Africa, again and again and again, the well meant initial independence regimes almost always collapsed amidst allegations of corruption and incompetence by the civilian administrations put in place, and the military regimes that intermittently followed were almost always worse. These were often followed by tin pot, cruel dictators who mismanaged their countries relative to the colonial regimes that preceded them. When India finally gained independence, it was only after an adequate indigenous class of civil servants and lawyers was in place, and a lengthy campaign by unified political/protest movement had created a sense of national unity with grass roots support and a class of political leaders to implement the new government. Even then independent India soon divided into Hindu majority and Muslim majority regions in an event that was a apocalyptic national trauma with blood running in the streets, and in the Muslim part, coups and a national schism soon followed again. It would only have been worse in 1857, for everyplace except perhaps a small kingdom in the region where the mutiny took place, with everything else fracturing (not that it was fully unified in 1857 under a consolidated British rule in any case). [Answer] If the war succeeded, all of northern India east of the Sikh Empire would be free from the British, these regions include Paniput, Delhi, Agra, Bihar, Bengal, and Assam. The mutineers put the then Mughal Emperor as a unifying symbol. So if the war succeeded, the monarch would bee Mughal. The muslims today will be free of Hindu atrocities and oppression, and would later recieve friendliness and alliance from the well off and rich ruler or Hyderabad Sir Mir Nawab Nizam Osman Ali Khan. And that Mughal Federation would today be a prospering sate since it would be rich in natural resources and they wouldn't be overused as the population would not be humungous like modern india. ]
[Question] [ Suppose we have an intelligent alien who has landed on Earth and has somehow found his way into a human high school math class (for the sake of scenic stability, the alien has the ability to cloak itself as a human form). The typical trope is the alien finds the human math elementary, and quietly chuckles to himself about how primitive humans are. Sometimes the alien, when interacting with his human friends, mutters advanced mathematical equations to himself, which goes right over the humans’ heads. In our high school math class, the alien gets called up to the board and sometimes inadvertently fills up the entire blackboard to the shock of the human teacher. For example, in the Animorphs series, there’s a line where Ax (an alien posing as a human teen) says in a train of thought: > > I think I remember the equations ... in an equation where *t* is time, *z* is Zero-space, *w* inversely cubed represents the nexus of… > > > But how realistic is it that an alien would have the same concept of algebra as we do? Would our equations even make sense to them? Would theirs make sense to us? Would they even have “equations”? Would they have the concept of things like a variable or a square root? Would things like “subtract *x* from both sides” make sense to them? Note that I’m not asking about *symbols*—we assume that, just as our friendly space alien has learned the English alphabet, he also knows about human symbols such as `+ – = × / √`, etc. He also speaks the English language well (or has a translator chip in his brain). I’m also not asking if the alien would have problems with arbitrary conventions in our mathematical system (i.e. base 10, 360° in a circle, etc), rather the underlying system of logic. I’m asking that, if our mathematical *glyphs* were intelligible to our alien, would he feel right at home performing algebraic operations on Earth? If our alien came from a planet with a completely foreign algebraic system, how quickly could he pick up “human” algebra? How much of his native algebra knowledge could be transferred to his new context? [Answer] While the symbols we use to describe mathematics are a human creation, the underlying truths of math are not. The relationship between π and the radius/circunference of a circle, the square-cube law and the relationship among speed, time and distance were part of the universe before humans existed, and will continue to be after humans are gone. Any aliens who have enough technological advancement to come to Earth and disguise themselves **as an act of engineering** should have an understanding of Math in the very least equal to ours, even if the way they abstract math in their heads and recordings is different from ours. For such aliens, learning our algebra could be like what learning chinese or japanese is to a regular western person. Not only the symbols are different, the way you have to organize your thoughts so that you can give meaning to an idea and express it is different too. But the things you can talk about in those languages are the same things we can talk about in English, even if some things area easier to express in one language or another. As an exercise on reorganizing your thoughs to abstract and express mathematical ideas differently, and with different symbols (or different meanings for the same symbols we use), you can also learn a low-level programming language (languages that force you to learn how a computer works in very minute detail) and play with it. You'll never see an equation the same way again. In the very least you will start using less and less base 10 and more and more bases 2 and 16 (and sometimes 8) in your head. I have been doing it for years, to the point that reading time from a watch like the one below is easier for me than reading time on an analog watch. [![enter image description here](https://i.stack.imgur.com/BJpgi.jpg)](https://i.stack.imgur.com/BJpgi.jpg) (It says 12:15 by the way) Another example of how some programmers are practically aliens when it comes to Math. The "equation" below (actually a simple program written in [Brainfuck](https://esolangs.org/wiki/Brainfuck)) is a simple addition. It works if both values are zeroes or positive integers and the sum of their values is no greater than 255: ``` [->+<] ``` The best part of it is that the variables to be summed are **not** represented in that equation. And the "+" symbol there does not mean "add", it means "increase by one". I could not explain that in an answer here, and if I tried, the more I talked about it, the more you would think I am an actual alien. Once you've put yourself through the effort of learning a language that uses different symbols and requires you to reorder your thougths, you can use your experience to describe how learning our algebra should feel to an alien. How easy or hard that would be for said alien is up to your tayloring as the writer of your story. --- There is alternative here, though. If the aliens come to Earth as **an act of magic or psionics**, done intuitively or instinctively, then they may not need mathematical concepts. But this does not mean they could not have them. [Answer] There was a SETI Weekly Seminar a while back on just how alien maths might be. See [Contact with ET using Math? Not so fast. - Keith Devlin](https://youtu.be/KveKjHIipgo) and [ET Math: How different could it be? - John Stillwell](https://youtu.be/9MV65airaPA). > > We like to think that intelligent aliens would have the same basic ideas about numbers and geometry as us, but, even if they do, they might express those ideas very differently. To illustrate what different forms a concept can take, I will show how differently the law ab=ba has been interpreted at different times in human mathematical culture. This seemingly basic law has several different origins -- in geometry, number theory, and set theory -- some of which seem alien even to experienced mathematicians. > > > [Answer] Interesting question. I tend to say it's "just" a matter of learning the mathematical symbols and the rules for manipulating them. Mathematic is a language and this one needs to learn it. Now one is able to discover patterns and constants. For example, the alien might learn that pi is the ratio of the circumference and the diameter of a circle and that it is always the same, say a constant. If the aliens have a concept of a circle then it is likely that they have also a symbol for pi. In that sense it may look familiar to the alien once it understands our mathematical language. [Answer] Any species would have a notion of counting - at the very least, a farmer needs to know whether he has the same number of sheep at the end of the day as he did at the beginning. Once you have counting, you have addition of whole numbers. If the concept of a rectangle occurs to you, then multiplication is the natural next step. Now, you might not consider a rectangle to be a sensible choice of shape - an alien species might perhaps think that triangles are the right way to arrange groups of objects, and then instead of $x \cdot y$ they might use an operation $x \oplus y = (x \cdot y) / 2$, or something weirder. Here's where I think the first major divergence opportunity kicks in. Humans, at this point, abstracted a little and moved from counting objects to measuring lengths and areas; an alien species might not make that leap at all, and might decide that the only number that exist are the whole numbers. Then division becomes complicated - if there are no non-integers, then $3/2$ makes just as little sense as $1/0$. Unfortunately, there wouldn't be much else to work with unless they eventually did decide that non-integers exist - math would stall here. If they accept rational numbers, then division is the natural next step. Here's the next divergence - if they made the leap of connecting numbers to distances, then square roots will happen immediately, because there's no other way to deal with triangles. If they didn't, and they just decided division was okay anyway, then they might stall again. Algebra would happen as usual, at least to begin with - if you care about patterns, which you have to if you're going to do math at all, then replacing numbers with symbols is the objectively correct next step. BUT - exponents could easily go a different way. $x$ is a length, $x^2$ is an area, $x^3$ is a volume - you could insist that $x^4$ doesn't exist, because it doesn't have a physical analogue. So an alien civilization might have functions $S(x)$ and $C(x)$ meaning $x^2$ and $x^3$ respectively, and they might know that $x \cdot S(x) = C(x)$, but they might think $x \cdot C(x)$ is gibberish in the same way that $1/0$ is. [Answer] All our mathematics is built on top of our logic, with concepts of "true" and "false". However what if the alien logic doesn't have those concepts? What if they have a sort of fuzzy logic where things can be "more true" and "less true", but not "absolutely true" or "absolutely false"? Such an "inconclusive logic" would certainly affect all of their mathematics. For a start, many of out paradoxes would be completely incomprehensible to them. First, they'd have a problem to even understand the concept of a contradiction, as in their logic, a sentence could be neither true nor false, as they don't have those concepts. Also, they couldn't even formulate a sentence like "This sentence is false", the best they could do is "This sentence is less true than its negation". Now, one important proof method in mathematics is proof by contradiction. They wouldn't have that in their toolbox. On the other hand, they would likely have developed other tools that work better in their logic (but may be problematic to describe in ours). Not to mention that a "proof" in their mathematics would be something very different from a proof in our mathematics, as their proofs wouldn't establish truth (remember, that's not a concept in their thinking), they would just *increase the trueness*. In turn, several different proofs of the same fact might not be seen as redundant by them, but each independent proof increases the trueness of the claim. [Answer] Learning the symbols and getting used to base 10 will be the two major problems, then there are certain conventions such as Cartesian coordinates, the "width" of a degree etc, but everything else is transferable. I'm reading a book on the history of the computer and it said that a lot of mathematicians in the early 20th century had problems working with bases other than 10 which prevented many of them from coming up with the idea of electronic computer. Given that your alien is fairly used to different bases, it should be fairly simple for him to "learn" high school algebra. First thing would be to get familiar with the integer set and the basic operators. Properties of sets and set operations are universal, same for boolean logic, therefore it should be fairly straightforward to learn the basic operations (+, -, \*, /, power, =, parenthesis) by looking at equations such as: ``` ... Identity for +,- 0 + 0 = 0 ... Transitive Property, similarly for the other equivalence properties 0 + 1 = 1 1 + 0 = 1 1 + 1 = 2 ... So forth demonstrating 0 - 9 9 + 1 = 10 ``` If you take a leap of fiction and stipulate that the whole world uses SI units, you'll make your alien's life much simpler. [Answer] Mathematics is completely made up by humans, so the answer is very probably no. Counting is present in a lot of species; the ability to track the number of objects is important. This later evolved from a simple tally system to a numeral system like we have today. This sort of system is a reasonable assumption, it facilitates all sorts of things like including trade and agriculture. As a presumably space-faring civilisation, they would have to have some understanding of physics, so they'd need a way of dealing with that too. It's possible this would involve mathematics, but not necessarily certain. Variables play an important roll here, so I'd guess so. They would have equations, you can have an equation without mathematics after all. Indices aren't actually necessary for maths, they're technically just shorthand for lots of multiplication. As for algebra, that's the border of the realm of pure mathematics, which has little to do with the real world. Algebra as a concept would likely make little sense to an alien, why are the earthlings adding letters together? Since algebra has a simple, consistent logic I don't think it would take long for them to figure out how it works. [Answer] Mathematics is based on logical Euclidian type [proof](https://math.stackexchange.com/questions/768944/is-all-of-mathematics-based-on-logic). That type of "straightforward" rational logic Is not necessarily shared by aliens. Even for human populations, non-westerners often have problems with [I.Q. tests](http://wilderdom.com/personality/intelligenceCulturalBias.html), logic, or problem solving designed [for westerners](http://opinionator.blogs.nytimes.com/2012/06/03/philosophys-western-bias/). Aliens could use a different type, like irrational, associative, emotional or non-linear logic. Even something as simple as **1+1=2** could be radically different. The logic could be: * **1+1=1** Like in 1 water + 1 water = 1 water, 1 white light + 1 white light = 1 white light, 1 red + 1 yellow = 1 orange, 1 hunger + 1 hunger = 1 hunger, 1 eater and 1 sandwich the sandwich is gone, eaten but the eater remains, 1 male and 1 female become 1 couple,...the goal of yoga is union, so this is fusion so, 1 + 1 = 1 * **1+1=3** 1 billing hour + 1 billing hour = 3 billing hours, ask lawyers or financiers about this one, 1 husband and 1 wife make 1 baby, so 2 becomes 3, the red-yellow previous addition could also be counted as orange which is made of red and yellow, so 3 colors are there, so it really depends on perception. All procreation relies on this so, 1 + 1 = 3 * **1+1=0** 1 alcohol + 1 alcohol = 0 alcohol, they both evaporate, 1 stain + 1 cleaning product cancel each other so = 0, 1 traveler and 1 plane, there are no longer here, so they are both gone, so = 0, 1 army and another conflicting army kill each other so no one left at the end, 1 fat man + 1 diet = no more fat man...This could be seen as mutual destruction, in a way it can be seen as 1+ (-1) = 0, but in other cases it is dissolution, were 1 + 1 = 0 * **1+1=x** All the previous examples are still based on human logic and perceptions, maybe for the aliens 1 cat and 1 trombone = 42 or µ² Actually, maybe the aliens wouldn’t even understand the concept, or the need for addition. **Edit** I admit that my examples are not very good and some have no have no logical consistency, but I am not a logician and I just came up with some various illustrations, and interpretations, of how 1+1 may not be 2. I have rarely such number of DV in so little time, plus a request to close and being put on hold, particularly given the research and time it took me to seriously answer. DVs are supposed to be for bad answers with no research, not because you don’t agree. I wanted to give an alternative answer, I could easily have just unthinkingly brayed: *“Math is universal! End of the question!*", like some fanatical priest. To me this shows that without really questioningt it, they just accept this axiom as true, and automatically rejecting any notion that math may not be a universal language. You may not agree, that math is subjectively based on our perception of the world and there are valid arguments why you may not, but the universality of mathematics has been a valid [debate](https://www.physicsforums.com/threads/dividing-1-by-three-proves-math-is-not-a-universal-language.679368/) for over 2000 years. Some constants like Pi, plank units, the speed of light are [fixed](https://en.wikipedia.org/wiki/Physical_constant), they are inherent and not mathematically constructed, or dependend, on our mathematical understanding. Yes, mathematics has self logic and consistency but it is like a closed circuit philosophical system. I could also argue that if it was even close to an “universal” system, or even a good system, we would know all about **prime numbers**. They seem to be the fundamental building blocks of the universe and our human math only know they are there and where their [shadows are](https://en.wikipedia.org/wiki/Riemann_zeta_function). > > What you are describing is nothing to do with mathematics. – Aron > > > In a way that's my point, math is a human logic language based on arguments. It is a way for our primitive brains to grasp the universe. It is based on our perceptions of counting units like pebles and 2D surfaces like circles. They are other types of logic, which math, in its limited scope, declares false or not relevant, like the 9 tailed cats of [equivocation](https://thelycaeum.wordpress.com/2012/11/25/equivocation-an-airtight-argument-for-nine-tailed-cats/). A basic search reveals a plethora of them like [alternative logics](https://en.wikipedia.org/wiki/Non-classical_logic), [Logic and Mathematics not Universal nor Absolute](http://blog.markhamanderson.com/logic-and-mathematics-not-universal-nor-absolute/), [Math: the Not-So-Universal Language](http://www.edweek.org/ew/articles/2005/07/13/42math.h24.html). Plus there is lots of evidence of math being culturally subjective, [Math a NOT so Universal Language](http://www.tsusmell.org/downloads/Conferences/2006/Luchin_Closing_2006.pdf), or [a universal language… or is it?](http://twentyinparis.net/2013/12/18/math-is-a-universal-language-or-is-it/) ]
[Question] [ Suppose that a planet whose size was somewhere between the sizes of Mercury and Jupiter impacted the Sun. Would such an event change local stellar activity sufficiently enough and for long enough that Earth's climate would be affected? [Answer] **[Mercury](http://en.wikipedia.org/wiki/Mercury_%28planet%29) vs. the [Sun](http://en.wikipedia.org/wiki/Sun)** * **Mass:** Mercury - $3.3022×10^{23} \text{ kg}$; Sun - $1.98855×10^{30} \text{ kg}$. Mercury clearly won't so much as jostle the Sun. There should be no major changes in the Sun's orbit around the galactic center. * **Composition:** Mercury - oxygen, sodium, hydrogen, and iron; Sun - hydrogen and helium. The extra elements shouldn't affect the Sun's fusion process, especially given how scarce they are. **[Jupiter](http://en.wikipedia.org/wiki/Jupiter) vs. the Sun** * **Mass:** Jupiter - $1.8986×10^{27} \text{ kg}$; Sun - $1.98855×10^{30} \text{ kg}$. Jupiter could perhaps perturb the Sun a little if it hit it right on. * **Composition:** Jupiter - hydrogen and helium; Sun - hydrogen and helium. The Sun would gain a little fuel, but not enough to cause a substantial change in the Sun's fusion. In both cases, the Earth should be fine. Sure, there could be a solar flare or two, but not anything substantial enough to severely impact the Earth. There are two interesting side effects of such a collision, and while they wouldn't impact Earth, they're still worthy of mention. First, the collision of a gas giant with a star would increase the lithium-6 concentration in the star (see [Israelian et al. (2001)](http://adsabs.harvard.edu/abs/2001Natur.411..163I) and [Melendez et al. (2016)](https://arxiv.org/abs/1610.09067), who studied [HD 82943](https://en.wikipedia.org/wiki/HD_82943) and [HIP 68468](http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=HIP%2068468), respectively). Second, if the planet (again, assuming it's a gas giant) was a victim of orbital decay, then it could be torn apart when it reached the [Roche limit](https://en.wikipedia.org/wiki/Roche_limit). The resulting angular momentum transfer could drastically increase the star's rotation rate (see [Hellier et al. (2009)](http://orbi.ulg.ac.be/bitstream/2268/28276/1/nature08245.pdf)). [Answer] Neither the Sun nor Jupiter are "solid" masses. Speed of impact will make a huge difference. In a very slow impact, the Sun absorbs Jupiter with little more than a hiccup. Though I could see the sun having some flares and CMEs. If they are pointed at the Earth, the effects will range anywhere from a mild increase in the ionization of the ionosphere (better short wave communications) to a game over blast of high energy particles (kills all ungrounded/shielded electronics and electrical systems). In a high speed impact will likely eject some mass, again the direction of this is everything. I think @bowlturner has a [serious point](https://worldbuilding.stackexchange.com/questions/3665/how-solar-activity-will-change-if-impacted-by-a-planet#comment7671_3668). Jupiter *passing* the Earth (with its intense magnetic field) could be a huge problem in its own right. Fortunately, space, even in the inner system, is BIG. Lots of room to slip Jupiter past us. [Answer] **Yes** and **no**. Jupiter is 317 times more massive than the Earth and 1000 times less massive than the Sun. That's big and small. This would likely cause a solar flare due to disruption of the magnetic field which could potentially increase Earth's temperature resulting in climate change, cause damage to the ozone and wipe out electronic technology. Mercury on the other hand at 0.05 the mass of Earth would have little effect. [Answer] Given that Jupiter is mostly gas, surely it would both be pulled apart tidally and evaporate as it approached the sun. If that is the case then there would be no impact at all merely a diffuse addition to the Sun's mass. I suspect the same might be true of almost any planet - gaseous or not. ]
[Question] [ Most species which use blood (that I know of) use a heart or set of hearts to pump their blood around their body. However, in something like our digestive system, a series of muscles are used to force digested food through tubes instead of a central pump. My question is, would using a similar ringed muscle series instead of hearts for a species work for pumping blood, or would it be too inefficient to consider? (for clarification, efficiency is in terms of energy required in proportion to blood successfully moved, and how easily the system could be stopped/interrupted) [Answer] # Earthworms: I think you are looking for a circulatory system like the humble [earthworm](https://sciencetrends.com/how-many-hearts-does-a-worm-really-have/). The very unique structure of the earthworm heart means it lacks a singular heart, but instead has a series of aortic arches that squeeze the body and force the blood through a closed circulatory system. The earthworm also controls this set of "hearts" directly via nervous system like we do, rather than by a secondary set of muscular signals. [![earthworm](https://i.stack.imgur.com/WZgbK.png)](https://i.stack.imgur.com/WZgbK.png) The question is, what kind of organism do you want to run with this setup? There isn't a lot of information to say how the arrangement works in a larger organism. [Cockroaches](https://www.livescience.com/49795-strange-animal-hearts.html) have a slightly analogous system with 12-13 separate hearts (depending on your definitions) to allow much greater redundancy in a fairly sophisticated organism. The loss of function of part of the system still allows circulation to operate. The cockroach model is using an open circulatory system, so it doesn't match quite as well. [![cockroach](https://i.stack.imgur.com/tH1eo.png)](https://i.stack.imgur.com/tH1eo.png) [Answer] This is literally how the circulatory system of insects works: [fruit fly video](https://www.youtube.com/watch?v=KY1wf6UXmjY) Now the context is different from vertebrates: insects have an open, non-pressurised circulatory system, and the dorsal vessel (the peristaltic blood pump) is not even a closed tube, but partially open and sort of just helping the haemolymph slosh around more efficiently. Whether this design would be sufficient in a closed circulatory system is perhaps debatable. But developmentally speaking, it’s pretty trivial: the heart is *already* basically a tube (well, a pair of tubes) knotted [around itself](https://www.youtube.com/watch?v=a0qyagIgBPw) [Answer] Yes, there are organisms where blood is moved by muscular blood vessels that "contract in peristaltic waves" ([source](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5378490/)). This is the known alternative to the chambered heart and is seen in some annelids. The largest and most conspicuous vessel in the earthworm traverses the full length of the animal. It collects blood from other vessels and drives it forwards through contractile peristaltic waves that originate at the posterior end of the animal and move forward. Peristaltic pumps lack coordination between the blood that is entering the contractile region and the blood that is leaving it. Despite some improvements to the peristaltic design, such as the evolution of one-way valves and coordination in contractions, the loss of energy associated with backflow, distension of wall segments ahead of the stream, and pump reversals constrain body size and metabolic activity. This promotes evolution of the true hearts [Answer] Rather than relying only on a single centralized heart pump to push blood around, humans also have [skeletal-muscle pumps](https://en.wikipedia.org/wiki/Skeletal-muscle_pump) sometimes called a ["second heart" in the muscles](https://veinatlanta.com/your-second-heart/) of the lower leg and foot. When running, these muscles periodically squeeze and contract, not only moving the body, but also squeeze reservoir veins deep inside the muscle, periodically pushing blood out of the muscle and allowing it to flow back in. Valves in those veins allow that blood to flow only in the correct direction (against gravity during the run). Even when standing still, those same valves prevent blood from sinking under the influence of gravity, moving the wrong direction and pooling in the feet. ]
[Question] [ I'm searching for a source of nutrients for a nomadic tribe that climbs a seemingly endless metal tower. They have been climbing for generations and are too high up to see any ground below. The structure they climb is only made of metal (so far). Their water comes from rain, condensation and maybe body fluids (however less advanced than in "Dune"). Their main food source is birds and other flying creatures they catch, collect and breed while traveling. I realize there is no source for carbohydrates, vitamins and fiber in this diet. I read [Nomadic Tribe of Herders - Source of Carbs/Other Nutrients?](https://worldbuilding.stackexchange.com/questions/79931), but it seems every answer includes "They have to eat plants or agricultural products somewhen in the year", but I wouldn't know how the people could get these things. [Answer] Dare I hope that this is some kind of [absurdist](https://en.wikipedia.org/wiki/Absurdism) scenario? It smells like that, and so I gave you a hopeful upvote. If you are unfamiliar, check the link. What you set out is the myth of Sisyphus, but in a scenario where you can riff on society and family, not just one lonely dude and his rock. That myth has deep roots and can serve you well. You do not need to worry so much about the fine points if that is the case. Eating birds will suffice. But if this is not Kafkaesque fiction and you just want some roughage for your nomads (are they nomads if they only go in one direction? I am intrigued!) , here are [bromeliads](https://en.wikipedia.org/wiki/Bromeliaceae) growing on a wire. [![bromeliads on a wire](https://i.stack.imgur.com/zOyD9.jpg)](https://i.stack.imgur.com/zOyD9.jpg) Bromeliads are also called "air plants" - many do not have roots as such, just structures to cling to their substrate. They get nutrition and water from the air. Pineapples are in this family, and so you can propose some sort of edible bromeliad, with flowers and fruit at certain times of the year. [Answer] Apparently, and I'm not 100% on this (it's something I always mean to look up and never get around to), you can survive, mineral and vitamin wise, on a pure meat diet provided that you eat the whole animal including the organs and some fraction of the bone; I'm not sure if this holds for avian food animals as well as herd beasts. My thoughts in terms of non-animal foods on such a structure would be the look at climbers and natives. Pretty much any structure will accumulate soil pockets. There are many trees and vines that can thrive even in very small pockets of poor soil. So there may be climbers that have their ultimate source down below and there may be plants that are native to the structure and make a living in the tiny pockets of soil at joints, etc... [Answer] It does depend in some way on what the structure actually is.. the original builders may have had gardens and green spaces at various intervals on the tower if it was intended for living on. The other thing you might want to look it is what the birds they are catching eat... presumably their must be some kind of vegetation for them to consume. As for what kind of vegetation, assuming there aren't gardens on the tower itself what about vines that have grown up the length of the tower? I'm assuming from your description the tower may have been built and abandoned a long time ago, more than enough time for vines to start growing up it. Both grapes and kiwifruits grow on vines and you could invent others to fit your world. ]
[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/74197/edit). Closed 6 years ago. [Improve this question](/posts/74197/edit) # Problem Movies like *Interstellar* or *Star Trek* would like to depict the ability to travel between stars, at speeds faster than light, as a technology which would revolutionize society and our everyday life, but if in the very near future, we discover some way of building spaceships capable of traveling faster than light, I was wondering if it would have any lasting and drastic effects on society, politics and everyday life within a decade or so. # Assumptions Of course how FTL technology would change society would depend on a few assumptions; these are what I consider the most realistic assumptions (updated in response to some comments or answers): 1. I assume that newly invented FTL would be expensive, short ranged and relatively slow: * The first interstellar spaceship would cost a lot, initially I said at least twice as much as the ISS to build and fuel, (though as pointed out it could be much more), since we don't know what the technology would look like, we can't tell the price, but it would undoubtedly be very high. * initially i said, that it would not be reusable, because i was thinking about an unmanned ship with exactly enough fuel to fly to a neighboring star, some answers did however point out that the technology may only be used within our solar system, in that case it would possibly be able to refuel and reuse a ship a few times, but that would both be expensive, and the ship would not last indefinitely. * it would at most be able to travel ten light years or so (due to limited energy storage capacity, this may change slightly if more resource is done, but don't expect to travel around the galaxy any time soon) * it would be able to travel at most three times lightspeed (and communication would be exactly lightspeed (of course you could send another FTL spaceship back and forth with messages, but I do think that would be way to expensive, therefore I think the very first FTL spaceship would simply use radiosignals)) 2. Space mining, and colonization in other solar systems would be just as expensive and difficult as in this solar system. (Some answers and comments have pointed out that this may reduce the travel costs, and with faster transportation the need to store resources on for instance a martian colony, and depending on wether the price of FTL is 2 times that of ISS or 10000 times that of ISS, it may be true that the price of space mining would drop somewhat, but both colonizing Mars or planets in other solar systems would still be expensive) 3. There is probably not life on any planets within the 10 light year range from us. 4. FTL technology would only allow us to travel in space faster than light, and would not for instance double as an infinite power source or a super-weapon, (or rather, an FTL ship could, as pointed out by Momarcil, also be used as a weapon, but what I meant was that for the first several decades, FTL would be so expensive, that ordinary nuclear weapons still would be a better investment). I also initially stated that the technology couldn't simultaneously make time travel happen, but as Fabbe pointed out, FTL may inevitably lead to time travel; but the method for time travel he outlined would require quite a lot control of the ship (so that it could first go the one way, then accelerate to 10% the speed of light, and go the other way), and for the first few decades after the invention, I don't think FTL spaceships could do that. Of course they may later be able to travel in time, but that wouldn't be one of the first effects it would have if invented tomorrow 5. Finally, FTL technology would, of course, keep evolving, but this will happen rather slowly, and the problems of the technology mention in point 1. would take several decades (and a lot of money) to overcome 6. Finallier (in response to comment: what is the effective minimum range for this FTL technology? from Mooing Duck), while I don't think there would be a technologically defined minimum range for FTL travel, I do think there is a distance below which the first FTL technology is to expensive to use compared to alternatives, that includes (probably) any shipping on earth, and (possibly) also surface to space and space to surface transportation (In the future this may change, but this question is concerned about what would when the very *first* FTL technology was discovered). It is quite possible that, as several comments and answers have claimed, FTL would be able to reduce travel time, and (depending on the technology) to some extend cost of interplanetary travel. # Question specification I am of course well aware that FTL technology would be a great scientific breakthrough, but in the case this question, *I only want to know if the life of the average human, and human politics in general, would change notably or at all*, because that ultimately is what decides whether or not the governments of the world would even want to invest in building and researching FTL spaceships. Specifically I am wondering if faster than light interstellar travel would have the same fate as Moon landings of the 1970s; which lost funding as soon as the public lost interest. Or if interstellar travel, – just like the launch of the Sputnik started the age of satellite communication – would mark the beginning of a new age. ## Requirements for answers FTL travel tends to generate some opinion based questions and answers, and therefore this question has nothing to do with whether or not it is possible, or what forms it would take if possible, it is only about the effects on society and therefore I only want answers concerning how society would react, not why FTL travel is not possible. Furthermore I want answers, which based on historical parallels, and/or the political situation of today's world, or logically argues whether or not FTL technology would cause notable change to society. [Answer] ### Not much. The two examples you provided (Interstellar and Star Trek) have two different means of FTL travel. The Interstellar model is much closer to modern technology, although certainly more advanced than what we have. The mission had finite resources, including energy, and had to make choices about which planets to visit. FTL travel was achieved via a wormhole, which is essentially a physical phenomenon that allows a spaceship to travel vast distances in space: no warp drive or other special propulsion mechanism required. Star Trek follows a different model, using a warp drive. The amount of energy required to power such an engine is ridiculously high, necessitating the use of a power source that may as well be unlimited. A science-fiction warp drive uses a power source more advanced than we have literally to bend space-time into a warp bubble which allows the ship to travel FTL without violating relativity. TL;DR the Interstellar mode of travel requires a lot of energy and the existence of a wormhole but we could certainly achieve it with an Apollo-level national effort. Star Trek or other warp drive technology requires vast amounts of energy impossible to achieve using modern technology. > > FTL technology would only allow us to travel in space faster than > light, and would not for instance double as an infinite power source > or a super-weapon (and it would not allow time-travel, at least not > the first several decades after its invention). > > > This is the crux of the issue. You are excluding the idea of a Star Trek type warp drive that would power FTL travel. No almost-infinite energy matter-antimatter annihilation power plant used to power a warp drive. --- One of society's major limitations is energy. With near-infinite clean energy we could almost eliminate pollution, build efficient robots to do most of our work, and generally enjoy the benefits of a post-scarcity economy. Without the type of FTL travel that brings easy energy along for the ride, we would not lift the energy burden from our world and would not make reality-changing progress. > > If FTL travel was invented tomorrow, would it change society? > > > Yes, but given the previous constraint, not a whole lot. There are people alive today who remember the 1960s space race and the Apollo program. Live video from the Moon was a huge deal. It united the U.S., even the world. The massive spending spurred technological advances (e.g. Velcro). However, it did not revolutionize day-to-day life. FTL travel would certainly impact the world, but I would look at it the same way as my country's football team winning the World Cup. We all still have to go to work tomorrow and all we get are bragging rights. With FTL travel mankind would get to explore the galaxy, but most of us would simply get to watch some cool videos on SpaceTube and perhaps reap the benefits of some minor inventions that came out of the space program. [Answer] Within the parameters you've set I think that FTL: * Wouldn't be comercially exploitable - too expensive to mine resources from distant moons. * Wouldn't be weaponizable. * Wouldn't allow us other world-changing technologies or discoverings (no alien life, no interesting phenomena like black holes or similar) I would say that FTL technology would be much more a question of study here on Earth than something that was going to change life as we know it for the common people. But then, FTL travel is something that, like flying cars or laser guns, we have been dreaming of from like, forever, and its mere existence would start a new space race with an intensity it has not been seen since the fifties. Don't discount FTL at 10 or 20c to be developed really soon, because the amount of money invested in developing that would be eye-watering. [Answer] Of course societies around the world will change immediately. But the amount of change will at first be very small. At the very beginning, we will of course be flooded with massive amounts of newspaper articles, tv shows and whatnot, any one of them misunderstanding the concept an the implications in various degrees. There will be wild and colourful dreams about the possibilities this breakthrough brings, hope, and of course fear. Need i mention the very small but very loud groups of people either claiming that this was a prof of god, or of doom, or both, or neither? After a while, some pop star will be dating someone new, and the headlines will forget about ftl and discuss other people's relationships, just as before. But the interesting things will be small and subtle. There will be funding for projects, eventuelly one project will be realized, and a first ship will be built. All this will cost money, as was pointed out, this money will create a few jobs, and will make some people happy and others unhappy. But most of all, there will be a lot of minor byproducts of all the efforts that are being put into creating this first ship. It will mostly be those byproducts that will influence the lives of the people, hardly noticed and in many small steps, but it will be there. Think about microwave ovens. They were a byproduct of the space race. They are by no means spectacular, they don't feed the poor or cure cancer, but they do have an impact. The same goes for sattelite navigation and countless other things that were invented while originally pursuing higher goals. Obviously, it is impossible to know what kind of interesting inventions your new techology will bring forth, but they will emerge, and will gradually change the lives of everybody. And while probably a bit boring, i think that this is actually what will happen. Not global peace, not post-scarcity, but a lot more knowledge in some specific fields for those who care, and a lot of improvements to many small things, and a few novel kitchen implements. Granted, this doesn't give you much of a story, but it's still something that changes societies, just not in huge steps. [Answer] FTL travels will have some important effects on technology, that then will affect society. FTL travels would, INDEPENDENTLY of what technique that is used, ALWAYS make it possible to travel in time, and THAT would have a great impact on society. The reason is because there is no objective simultaneity. Just by raising up from a chair and walk through a room, you change what moment is "now" in distant galaxies with hundreds of years! The only thing that stop causality to break the normal order is the fact that we (at least yet) cannot travel faster than light. So, let's say you travel 10 ly in one direction, from A (Earth) to B in 3 month. That mean that you transport yourself from a point in spacetime to another, that is in your point of view 3 month later. (That point of view is dependent of your velocity!). You start from A at 2100 January 1:st, and arrive at point B at 2100 April 1:st. At point B, you accelerate your ship (in the same direction you traveled), from 0 m/s to 29 979 245 m/s (10 % of the speed of light). The point that is "now" on Earth has now changed to be 2099 April 1:st! Now you travel back the same way (if you cant reuse the ship, just have another ship built on place before, waiting for you), and will arrive on Earth on the 2099 July 1:st, 6 month before you went away. If the FTL travel is used by another way and by a ship, i.e. a wormhole that you can create, you just create a wormhole on B that have the velocity away from A. If you teleport, you just do the same, but accelerate before accelerating back. If you believe in The Novikov self-consistency principle, based on Einsteins equations, a time traveler will not be able to create paradoxes. Therefore you can make situations there you demand to get the right answer from your future self, ("What is the solution to X"), and if the answer was wrong, you will send another answer in the future. To avoid paradoxes the natures easiest way is that you receive the right answer so you will send back the same right answer. "How do I create a fusion reactor"? "What shall I do to be happy?" "How will I save the environment", and so on. Beside all this time travel stuff, you will be able to create "back-in-time" spy satellites: Just travel 1 light hours away, and engage your super-ultra-telescope for looking at the light that was sent 1 hour ago, to see what happened (who killed the President, where did the car/airplane go, and so on). That can make the world a bit safer and better (or worser, with a bad government). [Answer] How can it not be weaponized by speeding up a large metal slug to post lightspeed speed? Beyond that I figure it would allow research outposts within our solar system like Titan. Mining will unlikely be economical and we still got the massive issue of getting things from Earth to space and back. It would effectively negate all distance within the solar system but beyond that all barriers against space travel seems to remain. [Answer] The first faster-than-light travel would not be by a ship, it would be by a few dozen particles in an accelerator somewhere. Initially, this would be dismissed as measurement error, bad methodology, or an outright hoax, assuming it even made it outside of the research team that saw it. It would be probably only decades later that the first paper discussing it would get published, and likely at least half a century before any practical applications are developed. Once we get there though, the first real-world application of FTL travel would not be material transport, but communication. Just point your FTL accelerator at the particle detector on the other side of a 5 nanometer gap in a cryogenically cooled vacuum chamber and you can transmit a message faster than light. Oh wait. Perhaps this will let us do some neat computing tricks? (like entanglement effects on quantum processors?) Someone will publish a paper on how to crack QES cryptographic keys with it, and nobody will care because we're still not remotely close to being able to use it in practice. And that will be it. Eventually the age of quantum computing will end and be replaced with FTL computing, and some other fundamental limitation on the way FTL travel works will be discovered that precludes using it for transporting anything but single subatomic particles. The media hype train might run for a while, but other than that, Joe Public will be completely unaffected. [Answer] Society will change, generally with a gradual increase in speed through amazement, horror, then general disinterest 1st: Society would react with awe and amazement the same way we viewed nuclear power though the 30's and 50's. Headlines and movies explaining the good that can come out of FTL Drives, Sci-fi movies dominated with finding alien life and colonizing planets will be somewhat of the norm. 2nd: We would figure out how to use it in military applications, if not directly, then for payloads and military ships (cost doesn't really matter when superiority is at stake). Ships could be outfitted with multiple drives with each one used in case of emergency (think Borg Transwarp coil in Voyager), and even though slow and expensive to set up, processing facilities could be set up for rare gasses and minerals (Astatine, Xenon and Krypton, and Rhodium, Francium and Astatine, respectively) 3rd: As it becomes more commonplace and more laws are passed to prevent mutual assured destruction we would then use it for more explorative applications such as throwing FTL satellites past our solar system to collect data on potentially habitable planets far into the future. Concerning the General population, they'll just say "whatever" and go back to watching YouTube. [Answer] FTL? Sure. Ppl will stop speculating as to whether anybody will ever discover a method of FTL travel. Millions of novels will seem old-fashioned overnight. People will spend very long periods of time doing absolutely nothing travelling to far away places for no good reason....on the back of taxes raised from people who would if they could but can't afford to go to college (or send/backstop their children) in order to be eligible for ever becoming an astronaut. FTL would change society massively. Once space becomes viable the only thing that (loosely) ties the rich & powerful & people with Big Red Buttons to moral actions (the fact they have to live on the same planet as the rest of us) will be null & void. More middle of the road reasons? Every change in logistical capacity ever impacts economies and thus societies massively. Societies are essentially groups of people that share a common economy. FTL will impact every one the 3 big indices.. Logistics determine economic viability in every 'real' industry. FTL rewrites the rules. Presumably FTL (and corollary discoveries) would include manipulation of new energy sources or old ones in new ways. Fuel..is..important..to..society.. [Answer] # Such a development would be a massive change The requirements you place (no time travel, no commercial viability, no associated interim developments, cost only thrice the ISS) are not compatible with the development of FTL travel along the lines that modern physics is looking. In fact, FTL achieved while satisfying those conditions would necessitate an even bigger disruption of modern physics than just the development of FTL travel by more 'normal' (i.e. less theoretically disruptive) means. In the early 1900s, Albert Einstein and Max Plank (among others) published papers that showed widespread fundamental failings in the Newtonian system at that time underpinning the scientific community's understanding of cosmology. Einstein won a Nobel Prize for his work on explaining the Photovoltaic Effect, and a new age of science was born. Quantum Mechanics, General Relativity, these disciplines were born almost overnight and there was a veritable explosion of research, publishing, and general enthusiasm both in the scientific community and the global community at large for physics and the physicists creating it. As our understanding of the world fundamentally changed, we found ourselves swarmed with new technologies, wonders that would have been impossible in the old Newtonian world. LASERs, transistors, GPS (and anything else going really fast and really far away and trying to tell where things are), scanning electron microscopes, the list goes on. Some of these were sort-of overnight things. Some of these took a while longer. And, of course, each of these things building off each other makes even more things. ## So what would happen overnight? You'd see a couple people, the people who invented this, raised to the level of global heroes. They would have a lot of power, a lot of influence and funding and fame. Someone gets the Nobel Prize in Physics for this. This gives them a platform, and Einstein used this to accomplish a lot of good in the world. There's not much reason to think an inventor in today's time would be philanthropic. You'd see some effects immediately, here, though the full ramifications could take a while to come into effect. These effects last a VERY long time: we still quote Einstein and the effects of his support for e.g. nuclear disarmament and not locking liberal scientists up for being 'Commies' continue to shape the world in which we live. You'd see immediate financial policy changes. The fastest will be individual investors grabbing tech stocks in related industries, followed by investment groups, but within a year you'll have countries making serious changes to their research grant programs and of scientific focus in general. ## Medium-term? You'll have a revival of the physical sciences. Physicists will make lots of money and lots of people will go to school to become physicists and some sort of related engineer (probably mechanical) and, as a result, biomedical interest will slow somewhat. Education spending will go up, and the way it's spent will change. Textbooks for middle school on up will have to be rewritten. Some young college students will be inspired by the new field and towards the tail end of the decade begin a second wave of research and development expanding upon the first and truly revolutionizing everyday things by relentlessly applying the new paradigm. Space fiction will become popular again, like zombie stuff is now. We already did space-everything pretty recently, so this might go differently, but expect popular portrayals of FTL travel to change to match the new scientific results at the very least. Since FTL ships can't be used as weapons (for magic reasons beyond our current ken), expect warfare to change. Right now, we are very much in an attacker-wins sort of situation. If FTL ships or the technology involved in them can somehow be used for defensive purposes, the world will become briefly a much more dangerous place and then a much safer one. Our most pressing reasons for space colonization would ironically be defused by the very technology likely to make it easy. [Answer] I'd say that it would be business as usual. NASA would send probes and have another way to fund their works program for engineers. ]
[Question] [ In this universe humans have advanced far enough to be able to colonize planets in our system but not enough to do interstellar travel. Earth is united and they have moved beyond countries and borders. Against a possible attack on any of the colonies on other planets, humans must have come up with a way to have a constantly open communications channel. The problem is, there will be times when planets are behind the sun (according to Earth). For those special times I'm thinking of placing a relay station that will orbit the Sun with about a 90 degree lead from Earth in the same orbit as Earth. How realistic is this and what other methods could there be? Edit: There are really good answers here and I think I should clarify a few things as the people who answered felt it necessary. You don't really need to read these if you feel like just writing a general answer, but if you want to add details, then these may interest you. * Earth is united, therefore small stuff like `energy costs` and `supply lines` will be taken care of by the UHF (United Humanity Front). * The UHF has colonized most of the planets that are plausible as colonies. Mercury is currently off limits but it's on the to-do list for the UHF. * If there's an asteroid that can be used for mining, there's either a mining base there or somewhere close-by and most moons are colonized, although neither has the equipment that a planet does. * Planets are independent of Earth in the sense that they handle their internal issues with their governments but they work more like a state government than anything else (so they're still bound by rules that the UHF sets but they can set their own rules too). This might seem irrelevant but this will also make sending messages to other planets and trusting them with those messages harder than it already is. (It would be like trusting Kansas to relay a message from DC to California, yeah it would most likely not be edited, but it might be.) * The UHF has been keeping a tight leash on the planets, there is no discontent among the general public but that's just because most people are living luxuriously and they wouldn't bother with an uprising. If there happened to be one, they wouldn't bother with stopping it either. There are rebel-ish groups but they're mostly irrelevant (the problems that will arise with the comm-system I'm choosing will have to do with a rebel group). [Answer] I am going to assume that by constant, you really mean constant as opposed to instantaneous. In other words, we are still bound by the speed of light propagation delay. We are also bound by the laws of orbital mechanics as currently understood. Since you use "planets" plural, I take it that humanity has colonies on multiple planets and possibly moons, as opposed to just one outpost away from Earth or Earth-centric orbit (which we already have one of: the International Space Station). I'm also going to, for simplicity's sake, assume that you have unlimited power output for the transmitters. In practice this is not going to be the case, but to a first order approximation to maintain reader suspension of disbelief, it works okay. Also, you can trade power output for data rate, as described by the [Shannon–Hartley theorem](https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem), so if you can accept a lower data transmission rate, you can make do with less power (to a point). **Let's start with colonies only on the planets' surface,** not any of the moons in the solar system. The problem here is that planets orbit the Sun with little regard to their respective orbital alignment with the other planets. The easiest way to ensure that every planet is always in view of at least one communications relay satellite is probably to put the relay sats in an orbit around the Sun which is highly [inclined](https://en.wikipedia.org/wiki/Orbital_inclination#Orbits) relative to the solar system ecliptic (the imaginary disk that is formed by the orbits of the planets, which traces back to the protoplanetary disk of the solar system). A simple way to do that (well, "simple", but still expensive in terms of orbital maneuvering to get into place) would be to use a **solar polar orbit.** This is an orbit that goes across the poles of the Sun, rather than around the Sun's equator, at a 90 degree angle to the ecliptic. Having three relay satellites in a solar polar orbit, 120 degrees out of phase, will ensure that there is always one within view of *somewhere* on every planet in the solar system, as the Sun will only block the view of one at any one time (as viewed from any particular planet). You may want a few extra for redundancy, but doing so does not significantly change the setup. Given that the other end of the link is close to the ecliptic, having three ensures that one is always within view of each planet, whereas with two, the situation could arise that one is behind the Sun and the other is directly in front of the Sun. That would almost certainly work from a geometric point of view, but in practice you would have serious trouble picking the signal out from the Sun's noise (see below). Now, notice that I said **somewhere** on every planet. You are going to need a similar constellation in orbit around each planet where there is a human colony, to ensure that there is a satellite in view of every point on the surface where it is needed. At this point it comes down to a similar scenario to that described in [Minimum number of satellites to image the entirety of Earth's surface at all times](https://space.stackexchange.com/q/8414/415). It turns out that this is possible to do with four to six satellites (mostly depending on your ground station capabilities, I suppose; four is the absolute minimum required for the satellite constellation to be able to see every point on the surface all the time, but you also need particular spots on the surface to be able to communicate with at least one of the satellites at any given time). Again, you may want a few extra for redundancy, but solving this problem is not an insurmountable task. **Once you add colonies on the planets' moons or otherwise in orbit of the planets,** you will need a reliable method for communication from the colony to the relay sats around the planet. For this, you can look to the [Tracking and Data Relay Satellite System (TDRSS)](https://en.wikipedia.org/wiki/Tracking_and_Data_Relay_Satellite_System) for inspiration. Long story short, you need at least three satellites in geostationary orbit to maintain constant communications between any point in orbit and any point on the ground, after which getting the signal to the solar system relay sats is merely a matter of getting a signal (any signal) from point A to point B on the planet's or moon's surface, or between the TDRSS-like satellites. Once the signal is within view of one of the solar relay sats, have the satellite shoot it off toward the solar relay satellite, and the signal is off to its penultimate destination. **There are two big problems with this that your world's engineers would be facing, which I can think of.** First, the Sun is rather noisy well into the RF spectrum. That's a problem when the Sun is in line with the desired signal. So you will need to either place the Sun-orbiting satellites in a relatively high orbit around the Sun to ensure sufficient separation that high-gain antennas can select against the radio noise of the Sun, or *extremely* high-gain antennas at the ends of the links. I don't know which of these would be easier, but given that fighting the ecleptic is already difficult, either might well be worth the price to pay. Note that the higher-gain antennas require more accurate aiming, which will require more station-keeping, necessiting more reaction mass ("fuel") on-board the satellites for a given service life. Again, not insurmountable, but worth keeping in mind as it is an issue that real-life engineers would have to contend with and make tradeoffs in. Second, solar polar orbit is hard. I alluded to this above, but don't dismiss the importance of it; it really is crazy hard. Let's say you want to place the Sun-orbiting relay satellites at the distance to the Sun of Venus (0.73 AU), with an inclination to the ecliptic of 90 degrees. First, you need to get to Venus' orbit, which can be accomplished with a [Hohmann transfer](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit) (calculated based on a heliocentric, or Sun-centered, reference frame): $$ r\_1 = 1.00~\text{AU} \approx 149\,598\,023\,000~\text{m} \\ r\_2 = 0.73~\text{AU} \approx 109\,206\,445\,611~\text{m} \\ \Delta v\_1 = \sqrt{\frac{\mu\_\text{Sun}}{r\_1}} \left( \sqrt{\frac{2r\_2}{r\_1 + r\_2}} - 1 \right) = \sqrt{\frac{1.3271244 \times 10^{20}}{149\,598\,023\,000}} \left( \sqrt{\frac{218\,412\,891\,222}{258\,804\,468\,611}} - 1 \right) \\ \Delta v\_2 = \sqrt{\frac{\mu\_\text{Sun}}{r\_2}} \left( 1 - \sqrt{\frac{2r\_1}{r\_1 + r\_2}} \right) = \sqrt{\frac{1.3271244 \times 10^{20}}{109\,206\,445\,611}} \left( 1 - \sqrt{\frac{299\,196\,046\,000}{258\,804\,468\,611}} \right) \\ \Delta v\_1 \approx 2\,423~\text{m/s} \\ \Delta v\_2 \approx 2\,622~\text{m/s} \\ \Delta v = \Delta v\_1 + \Delta v\_2 \approx 5\,045~\text{m/s} $$ which is managable (going to the Moon took a total of about 11 km/s delta-v for the trip out, plus some for landing and going back for a total delta-v budget of somewhere in the vicinity of 20 km/s split among the Saturn, service module, lunar module descent and lunar module ascent stages). This puts you in the neighborhood of Venus; not necessarily in Venus' actual location (that depends on orbital transfer timing, or what we refer to as [launch windows](https://en.wikipedia.org/wiki/Launch_window)), but at least approximately co-orbiting with it. Now, assume that your orbit is circular, and [change its inclination](https://en.wikipedia.org/wiki/Orbital_inclination_change#Circular_orbit_inclination_change) by 90 degrees while maintaining its circularity (technically, its eccentricity), where $v = 35.02~\text{km/s}$ is Venus' orbital velocity around the Sun: $$ \Delta v\_i = 2v \sin\left({\frac{\Delta i}{2}}\right) = 70\,040~\text{m/s} \times \sin\left(\frac{90°}{2}\right) \approx 49\,526~\text{m/s} $$ So if your satellite-carrying spacecraft is already in Earth's orbit (which is not the same thing as an orbit around the Earth, but rather, co-orbiting the Sun with Earth), you need a total velocity change (delta-v) budget of about 54,600 m/s to enter a solar polar orbit at Venus' distance from the Sun, and that's *after* you apply almost 8 km/s plus drag losses to get to low Earth orbit. While there are almost certainly tricks you can use to cut down on how much of this you need to apply under power (with rocket engines running), that remains a *massive* undertaking. I wouldn't be the least bit surprised if you'd be looking at something similar to the [Saturn C-8](https://en.wikipedia.org/wiki/Saturn_C-8), which was about the same height but much bulkier than the Saturn V which sent Apollo towards the Moon. Compare also [Is it possible to communicate in space while the sun is between parties?](https://space.stackexchange.com/q/4735/415) on the Space Exploration SE. [Answer] **Let the signals simply reflect off other planets, moons and shiny objects** In so-called [Radar Astronomy](https://en.wikipedia.org/wiki/Radar_astronomy), scientists send microwave signals as far away as to Mercury and Venus and are able to measure the signal reflected back at us! You may also have heard that a laser is bounced off a reflective plate on the Moon, left there by apollo astronauts. What this goes to show, is that your civilization does not need a relay station around the sun, they only need a reflective object. A "mirror" in orbit would do fine, perhaps a chunk of ice further out, a polished comet? Or perhaps mirrors strewn around Mercury, it having no atmosphere. There is some precedent to this in Earth orbit. In 1960, the US launched **Echo 1** a highly reflective *inflated* satellite that allowed people on earth to communicate by bouncing radio signals off it. Below is a picture of Echo 1 being tested at NASA and of [LAGEOS 1](https://en.wikipedia.org/wiki/LAGEOS), which was launched in 1971. The LAGEOS satellite reflects laser light and was not intended as a communication relay. Instead it is used to measure distances. And as background for a scifi story perhaps? You see, the LAGEOS satellite is still orbiting earth but is expected to crash into our atmosphere in 8 million years. It contains a plaque designed by Carl Sagan, meant to be understood by any intelligent creatures living on the planet at that time. Will it be understood? [![enter image description here](https://i.stack.imgur.com/h234P.jpg)](https://i.stack.imgur.com/h234P.jpg) [![enter image description here](https://i.stack.imgur.com/ALMdS.jpg)](https://i.stack.imgur.com/ALMdS.jpg) [![enter image description here](https://i.stack.imgur.com/rWhWy.jpg)](https://i.stack.imgur.com/rWhWy.jpg) [Answer] Three or four satellites around each planet, high enough so they see each other and one is always visible from any place (except polar latitudes) on the ground. For a reliable system, eight satellites might be a safer bet. You'd want to be able to connect to two of them to minimise loss during switchover. Plus two (one is essentially redundant) additional communications platforms in earths Lagrange points 4 and 5. That way you always have at least two clear views at every spot in the solar system. You'll want to add these lagrangian platforms to all planets so you can always connect directly between any of them. Saves bandwidth and delays. The routing will be an interesting piece of applied math, not only calculating the best pathways, but especially the optimal time to switch between routes, depending on their variable bandwidth. [Answer] According to NASA, during [Solar Conjunction](http://mars.nasa.gov/allaboutmars/nightsky/solar-conjunction/): > > They collect data from others and store it. In some cases, they continue sending data to Earth, knowing that some data will be lost. > > > OK, so this isn't great, but sun does not block communication totally. Relay station on orbit that's not on ecliptic might help, but there will be problems with it: * Maintenance issues * Once upon a time it might be in solar conjunction with either of these planets For this reasons, I'd prefer using another planet, or colonies in [The Belt](https://en.wikipedia.org/wiki/Asteroid_belt) as relays. First, there will be many of them, and second, they will take care of their comm maintenance anyway. Of course, fees during conjunction will skyrocket, but well, anything comes with a price. [Answer] **This is not a realistic problem.** You haven't clearly explained why the communication channel is necessary, but from the context of your question I assume it's so Earth can launch a defense fleet to defend the colony planet. Let's consider Mars, since it is the closest planet that is remotely habitable ([the surface of Venus averaging 467 degrees Celcius, hot enough to melt lead](http://www.space.com/18526-venus-temperature.html)). The optimal minimum-energy launch window occurs roughly once every two years and lasts roughly a month. This occurs at a point [when the difference in orbit between the two planets is 44 degrees](http://www.forbes.com/sites/quora/2016/03/15/when-is-the-best-time-for-a-spacecraft-to-launch-to-mars/#305ce58d1c6a), meaning the sun is certainly not obscuring line-of-sight between the two planets. This transfer flight plan takes roughly 260 days to reach Mars. Faster flight plans are possible, but they require considerably more energy. With a one-month transfer window that only occurs every two years, your odds of the ~~alien attack~~ coup occurring at the optimum time are very low, and even then if you get lucky it's going to take two-thirds of a year to reach Mars. Furthermore, if I understand [this article](http://natureworldreport.com/2015/06/curiosity-and-opportunity-left-on-their-own-mars-hides-behind-the-sun-in-june/) correctly, we only lose line-of-sight communication with Mars for a few days every two years. If it takes well over half a year to fly to Mars in the best case, and Mars is never out of sight for more than a few days, that loss of communication is extremely insignificant. If your ~~aliens attack~~ coup takes place on a further planet, it will take significantly longer for a fleet from Earth to arrive. To give you a sense of scale, Jupiter is the next planet out in the solar system after Mars, and [it takes *six years* to fly to Jupiter.](https://www.thrillist.com/tech/transit-times-to-planets-how-long-would-it-take-to-get-to-mars) ~~If your alien species is advanced enough to launch an attack from outside our solar system~~, they are probably intelligent enough to plan their attack in such a way that maximizes the time it would take a defense force from Earth to arrive at the planet. So travel time will probably be closer to worst-case scenario than best-case. # tl;dr It takes so long to fly to another planet that short gaps in communication when the planet is eclipsed behind the sun are not worth worrying about. [Answer] Why not model TCP/IP Ethernet protocol. where you can have many transmitters, and relay/routers that will build a resiliant routing table to send communications to the fastest route available at the time This will give fault tolerance and allow for adjustment to communication stations going down. Focused directional transmissions would take less energy but more maintenance. Also let's not assume we are alone in the universe, focused transmissions might keep most transmissions virtually silent outside of the intended target. I can only assume like people some other worlders are good and some are not. There is plenty of sun for power outside our atmosphere. so earth satellites and moon stations might be the first layer. Sometimes Mars is close to our orbit and sometimes it is on the other side of the sun, which is far. so communication times will vary from anyplace other than the moon. [Answer] put 2 an artifical planets (can't call them a satellites) in an elliprical polar orbit around the sun, they'll spend most of their time ouside the eccliptic, and thus atleast one should be reachable at any time [Answer] Maybe a mesh network in or near the asteroid belt? Lots and lots of very small, very cheap and also cheaply replaceable relays networking the entire belt increases the odds of being line of sight with one or more of the satellites and all of the satellites being line of sight with at least one other. Sow them out slightly above or below the plane of the ecliptic. The redundancy factor means that the system would be much more robust than a handful of relay satellites. The downside is that the speed of light is a non-trivial factor. By the time the message reaches earth, the aliens have packed all of the colonists into TV dinners. [Answer] It's simple! Look at the **Star Fox 64 map**. Install a big antenna on the planets that the UHF has colonized. They will be connected to one each other, avoiding the Sun. If there is a planet trying to communicate with one behind the Sun, simply find another relay station (planet) to get your message to the receptor planet. Look at this: [![the Star Fox 64 map](https://i.stack.imgur.com/lfhcP.jpg)](https://i.stack.imgur.com/lfhcP.jpg) Of course, there is software controlling the RF. [Answer] I would recommend a similar approach to actual phone lines nowadays: an array of repeaters spread across all planets (right now they're just on top of buildings or mountains) so even if the Sun is between the original signal and the Earth there will be repeaters all around it. [Answer] There is a real phenomenon that defies the limitations imposed by the speed of light: Quantum entanglement, where two quantum entangled particles function in such a manner, that a state change in one of the particles instantaneously affects the other. This phenomenon theoretically ignores any kind of distance, so it would be an ideal basis for communication. If it could be leveraged for such a purpose, one such pair would provide unlimited bandwidth between two points. So, you could create an interplanetary or even intergalactic internet using that. ]
[Question] [ In a previous question, I [established an area that creates megastorms](https://worldbuilding.stackexchange.com/questions/79356/cauldron-of-storms-geography-to-create-and-isolate-localized-mega-storms). Unlike a bunch of my other questions, this one is incredibly straightforward: Just how deep does a submarine (Or aquatic life, for that matter) have to dive in order to safely ignore a large-scale storm? It doesn't necessarily have to be completely calm, but low enough that the vessel could tolerate any issues that arise. For reference, the technology level would be late WWII-era submarines. [Answer] # At least 400 ft deep. [A similar question was asked on reddit](https://www.reddit.com/r/askscience/comments/3afx1u/are_submarines_affected_by_storms_in_other_words/). To quote [U235EU](https://www.reddit.com/r/askscience/comments/3afx1u/are_submarines_affected_by_storms_in_other_words/cscjodc/), who paraphrased the [US Navy Submarine FAQ](https://web.archive.org/web/20150420232753/http://www.navy.mil/navydata/cno/n87/faq.html) (now unavailable): > > **Violent storms may be felt as deep as 400 feet** (see [item 21](https://web.archive.org/web/20150420232753/http://www.navy.mil/navydata/cno/n87/faq.html)). The deepest we ever felt surface effects was about 150 feet and it was pretty good sized storm on the surface above us. > > > That being said, multiple navymen on quora suggest otherwise, such as [here](https://www.quora.com/Can-you-get-sea-sick-on-a-submarine#__w2_KoQTG3R_answer) and [here](https://www.quora.com/How-dangerous-is-a-hurricane-to-a-deployed-submarine). Finally, The Huffington Post post covered [What Happens Underwater During a Hurricane?](http://www.huffingtonpost.com/2012/11/02/what-happens-underwater-during-a-hurricane_n_2066084.html) ## EDIT: The referenced Navy submarine FAQ was cached on the [Internet Archive Wayback Machine](https://web.archive.org/web/20150420232753/http://www.navy.mil/navydata/cno/n87/faq.html)! The full text reads: > > During normal weather conditions, a submerged submarine will not rock with the motion of the waves on the surface. In fact, during even moderate storms the submarine stays perfectly level at its submerged depth while the waves crash above. **In extremely violent storms like hurricanes and cyclones, wave motion can reach 400 feet or more below the surface.** Though not as violent as on the surface, these large waves can cause a submarine to take 5 to 10 degree rolls. > > > [Answer] I have been diving in Cuba right after a major hurricane (the hotel I was staying in was the only one reconstructed and active). Devastation was to 15 meters. No sign of damage below 20m. [Answer] ## Periscope Depth on the open ocean Submarines in late WW2 were designed to handle overpressures of 20 bar (2.11169 MPa) at depths of 200 to 280 metres (660 to 920 feet). ([Crush depths](https://en.wikipedia.org/wiki/Submarine_depth_ratings)) Structures that strong can easily handle the pounding that a very large wave is going to dump on it. The humans inside the submarine won't like the jostling but the sub will survive. The shallow turbulence from the crashing waves is what the submariners feel at depth. The sub itself isn't in any danger. Remember that submarines aren't designed with a hull shape that induces rotational stability like surface ships do. ## Shallow waters are a different story Because of the turbulence from very large waves from these megastorms, the waves may be large enough to force a sub to drop further in the water column than it should. If the ocean bottom is too close then the sub may crash. The exact effects will depend on ocean bottom composition, angle of impact, speed of impact and luck. Shallow water during a storm would be dangerous to a WW2-era submarine. [Answer] Not that deep. 50 meters should be enough to ride through a major hurricane. <https://www.reddit.com/r/askscience/comments/15b1jo/how_far_underwater_do_the_effects_of_a_storm/> [Answer] <https://www.seasteading.org/the-seasteading-institute-policy-on-submersible-seasteads/> – > > While it is possible to escape the full force of an ocean storm by submerging beneath the waves, doing so is not nearly as simple as some in the forum suggest.... *To completely escape the sub-surface pressure variations from such a wave, one would have to be more than 500 feet below the surface. [152.4m]* > > > > > Even larger vessels like military submarines have to dive deeper than 100 feet [deeper than 30.5m] to ride comfortably in stormy seas. > > > [Answer] Category V S.S.S. with bottom plateau at 5K fathoms, experienced 2 degrees of roll until heading was changed by captain. Depth 560 ft. Then no appreciable movement was experienced. This according to chief bosun's mate. Cannot explain more detail. ]
[Question] [ What did smiths/metallurgists know about why some steel was stronger than other steel in the early 15th century in Western Europe? I want to know so I can determine whether my mages could come up with a spell to increase the strength of steel by removing impurities via magic or not. If they could come up with wording for the spell in the "magic language" they could cast it, but do they know enough to do that? [Answer] For a very long time (say, before the 16th century) they did not even know that steel and iron were different materials, and they had only very imperfect hit-and-miss processes to harden iron (by building a thin layer of low-carbon steel on the surface, but they did not know that). (Note: That's in Europe. The Chinese did have cast iron, which is very obviously a different material, and the Indians had a practical technology to make small but consistent amounts of low-carbon steel. Look up [Wootz steel](https://en.wikipedia.org/wiki/Wootz_steel); as user Mormacil mentions, Indian steel was an expensive and very desirable commodity, exported to the west to Persia, the Near East, and Europe, and to the east to China.) Before the development of modern chemistry and metallurgy, nobody had any good idea of knowing *why* a material had different properties from another material. At best they knew that if they followed a certain process they would get a material with certain properties; around this knowledge, there were weird and wonderful philosophical and even [mystical](https://en.wikipedia.org/wiki/Chymical_Wedding_of_Christian_Rosenkreutz) constructions with no practical application whatsoever. ([Phlogiston](https://en.wikipedia.org/wiki/Phlogiston_theory) or alchemical [transmutation](https://en.wikipedia.org/wiki/Magnum_opus_(alchemy)), for example.) Further musings: steel is not made by "removing impurities". Steel is an alloy of iron and carbon with a well-controlled amount of carbon. To make steel one can start with pure iron and add some carbon ([crucible steel](https://en.wikipedia.org/wiki/Crucible_steel)), or one can start with cast iron and remove some carbon (converter steel). Before the development of chemistry nobody even knew that iron and carbon were pure elements -- the prevalent theory in the late Middle Ages was that on the contrary the oxides (which they called "earths", hence our term "rare earths" for the metals in the lanthanide series) were the pure elements, and the metals were combinations of an "earth" and phlogiston, the pure element of combustion, a sort of negative oxygen. [Answer] I beg to differ slightly from AlexP's answer. Before a modern understanding of "steel" vs. "iron" was fully understood, a fair number of sword makers figured out that, not only were proper amounts of carbon required, but that much more hammering and tempering were also required for the best results (also, sometimes meteoric iron was found and used, which was far superior as a base material than scrape-mined terrestrial iron.) This understanding was first garnered in the Middle East (hence the fame of "Damascene Steel from Damascus.) Furthermore, early accidentally made excellent swords in early medieval Western Europe led to the myths of the great swords (Excalibur etc.) as inferior swords tended to be strong but brittle - meaning they just might crack and literally fall apart in battle. [Answer] Alternative solution: It's not usually possible for a human being to do anything well without coordinating their efforts with one or more of their senses. Imagine operating a construction crane with a blindfold on, doesn't work. This means they must receive some sort of feedback from the thing they are manipulating magically. Every action has an opposite reaction after all. Your Wizards may not know exactly what they need to do from a scientific perspective but they can use their senses to feel out an object and compare it against their experience with "good" or "pure" versions of the same object. They might describe this the same way cooks smell food and can tell if something has been seasoned correctly. Have them first "feel out" well-made swords and then ask them to make poorly made swords more like them. Have them experiment with making swords more this or more that to discover how to make swords surpassing that which can be made by even the greatest blacksmiths in the world. However, just like cooking, ingredients matter. You can't make a masterpiece with rotten goods. If this magic is based on science/reality, your wizards are going to have to carry around a good deal of material to work with. It may be common to see them traveling around with a cart of vials and powders that they reach into and rub over objects before working their magic on them. ]
[Question] [ As part of [Fortnightly topic challenge #3: Creature Design](http://meta.worldbuilding.stackexchange.com/questions/1862/fortnightly-topic-challenge-3-creature-design) I am looking for a realistic way to create a particularly nasty creature. **What I would like:** * A creature that is capable of emitting a sonic 'noise'...maybe wave is a better term * This ability should allow the creature to render higher order creatures stunned or unconscious for 30+ seconds, I would prefer the effect NOT be permanent. * By higher order I mean vertebrates essentially, if all vertebrates creates a problem specifically it should work on humans * Is a predator of the creatures it stuns **Questions**: * Can this be accomplished biologically? * What would the mechanism for such a skill be (both the process and the biological i.e. physical mechanism be...an extra organ maybe?) * How would this animal protect itself from its own abilities? * Are there any physical limitations having this power would necessitate, for example if there is a mechanism for this could it be slotted into a bear, a monitor lizard, maybe a kangaroo? [Answer] So, you want to build a banshee. **Examples** The [pistol shrimp](https://en.wikipedia.org/wiki/Alpheidae) is an interesting example, but ultimately won't work. It snaps open its claw so quickly that a cavitation bubble is created. This creates an acoustic wave of 80kPa (218 dB) at a distance of 4 cm from the claw. It's enough to kill small fish. However, underwater acoustics are less impressive in air, so this won't directly translate. In the air, against higher-order vertebrates, there are only artificial [sonic weapons](https://en.wikipedia.org/wiki/Sonic_weapon). The best examples have been used for deterring pirates and dispersing crowds, they are called [long range acoustic devices](https://en.wikipedia.org/wiki/Long_Range_Acoustic_Device). ![enter image description here](https://i.stack.imgur.com/T5tGg.jpg) **Frequency** To make this most effective for an animal, it would be best to use ultrasound frequencies. > > Studies have found that exposure to high intensity ultrasound at frequencies from 700 kHz to 3.6 MHz can cause lung and intestinal damage in mice. Heart rate patterns following vibroacoustic stimulation has resulted in serious negative consequences such as atrial flutter and bradycardia. > > > **Volume** That's frequency, the other component would be the sound pressure. > > Tests performed on mice show the threshold for both lung and liver damage occurs at about 184 dB. Damage increases rapidly as intensity is increased. > > > Now, [dB is not a unit of pressure](https://en.wikipedia.org/wiki/Decibel#Acoustics), it's a ratio of pressure, and thus unitless. But we can convert it to pressure easily. Additionally, saying 184 dB doesn't mean a lot without an associated distance, but we're stuck without that information. All we can calculate is that about 31.6kPa is being exerted somewhere along the travel from the transmitter to the receiving animal (most likely, though, it's at the surface of the animal). From this we can assume your creature will need to generate less than 184 dB acoustic waves in the ultrasonic range and be close range to the target for an attack. **Note about volume** It's important to point out that 184 dB is really loud. The loudest non-bass acoustic instrument appears to be the trombone, peaking around 114 dB. Many times quieter than required. Some bats have been recorded [at 135 dB](http://www.ncbi.nlm.nih.gov/pubmed/23630501). The loudest land animal is possibly the [howler monkey](https://en.wikipedia.org/wiki/Howler_monkey), topping out around 140 dB. I know it seems like 140 dB is pretty close to 184 dB. *It's not.* Decibels are a *logarithmic* scale. Every 3dB increase is a *doubling* in power. In air, 140 dB is only about 200 pascals (rms) while 184 dB in air is 31,698 pascals (rms). A 140 dB sound is like a jet engine 100 feet away, 185 dB kills hearing tissue, and [194 dB is the loudest sound possible in our atmosphere](https://en.wikipedia.org/wiki/Sound_pressure#Sound_pressure_level). **Reality** It *might* not be impossible that a creature could produce such a sound. But it's highly unlikely. It's orders of magnitudes higher than any existing biological sound. However, that is the maximum before permanent damage occurs. For your creature, it needs significantly less than that for stunning alone. So, such a creature is entirely in the realm of possibility. Even a howler monkey could disorient you with a scream if it had a mind to. **With that background, on to your questions.** > > Can this be accomplished biologically? > > > Yes, a set of lungs and an enlarged hyoid bone will do the trick. > > What would the mechanism for such a skill be? > > > It would likely be vocalization. Though other possibilities exist, [stridulation](https://en.wikipedia.org/wiki/Stridulation) comes to mind, and that would certainly look menacing. > > How would this animal protect itself from its own abilities? > > > It's a good bet that the creature itself is deaf or in the process of making the sound, temporarily deafens itself. **Bats do this**. When bats call for echolocation, a tiny muscle holds their bones of hearing in place while they echolocate so they don't deafen themselves. > > Are there any physical limitations having this power would necessitate? > > > This depends on the method used to create the sound. The most effective would be an array of sources, either vocal or stridulatory organs. This would allow for more directionality and focus. This would make the attack more effective over a longer distance and use less energy to generate. **The problem** It's really easy to avoid this attack. Simply wear ear plugs. Better yet, use active ear plugs, they simply don't transmit any sounds above a certain decibel level. Deaf people are inherently immune. [Answer] It's already been done. Two species of moth, the hawkmoth and the tiger moth, use not just sonic but **ultrasonic** signals to defend themselves from bat attacks. The hawkmoth has [only recently](http://www.natureworldnews.com/articles/2784/20130703/moths-use-genitals-defend-against-bat-attacks-video.htm) been discovered to do this. How? They use their genitals. No, I'm not joking. Have a look at [this](http://video.scientificamerican.com/services/player/bcpid1399191810?bctid=2522398017001) video (from Scientific American) showing the effect in action - the sound isn't that clear as our hearing range only goes up to ~21kHz and ultrasonic is above that, but the middle part of the video shows the process very clearly. (Perfectly SFW but your boss might throw you some strange looks...) There are [several](http://jeb.biologists.org/content/214/14/2416.full.pdf) different [papers](http://www.life.umd.edu/faculty/wilkinson/honr278c/PDF/Miller01.pdf) on the subject of natural sonic defense, though they are a bit long. The best way to defend yourself against your own weapon is to make sure it's outside of your hearing range. This is something that would very likely be evolved while the defence trait itself evolves: those who can hear it will also be stunned and then eaten when the predator comes to. Essentially, your hearing range just needs to be lower than that of your predator. Although the moth sound **doesn't** work on humans, it wouldn't take much to bring its frequency down to our hearing range, where it would in fact be incredibly loud - it's loud in enough in the ultrasonic range to jam bats' echolocation radar. Once this is done it would likely work on most higher-order vertebrates: humans have some of the worst hearing ranges in the natural world. [Answer] With the others, [dolphins](http://www.asknature.org/strategy/ca199b1cf731794fa0d8045acf9660db#.VP3xefnF_wo) will stun prey as well with sound too. the biggest thing of course would be the generating the shock wave, sound travels better in water, it dissipates slower and can do a better job giving a punch. So the assumption is, land based animal that can generate a stunning blow with sonics. Since we have developed [sonic weapons](http://en.wikipedia.org/wiki/Sonic_weapon) it is feasible to believe an animal could do so too. The [loudest animal](https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1CHFX_enUS603US603&ion=1&espv=2&ie=UTF-8#q=loudest%20animal) on earth is the [Blue Whale](http://en.wikipedia.org/wiki/Blue_whale) between 155 and 188 decibels. A jet is about 140. #2 on the list is the Howler Monkey, which can call up to 120 decibels. Now, for many species, you don't necessarily need just loud, but certain pitches can be very effective. High pitched sounds can be very disorienting for mammals, walking by the town siren when it goes off the first Wednesday of the month will make it hard for me to walk in a straight line. You also have large displacements of air. Flash bangs are just a loud boom that displaces enough air to mess with an inner ear. Having a croak like a frog on a large beast with directional capabilities could be a stunning blow, but those would have to be a little closer, high pitched sounds would have a larger distance but could also be directional, increasing it's effectiveness. [Answer] It's quite possible...and not simply through hearing. Sadly, humans over the age of 20 have experienced enough hearing degradation that it's difficult to disable them through sound without some more permanent effects such as breaking the ear drum itself. That said...Infrasound is likely what you want to go with here. Our ears are actually capable of picking it up, but it's never actually transmitted through to the brain. But more distrubingly, these infrasounds can cause our eyeballs to vibrate, which causes 'visions', mass discomfort, and a bunch of confusion. Vic Tandy (<http://en.wikipedia.org/wiki/Vic_Tandy>) : > > Tandy went on to recreate his experience, and with the assistance of Dr. Tony Lawrence, he was able to publish his findings in the Journal of the Society for Psychical Research.[12] Their research led them to conclude that infrasound at or around a frequency of 19 Hz,[2][10][13] has a range of physiological effects, including feelings of fear and shivering.[7][14] Though this had been known for many years, Tandy and Lawrence were the first people to link it to ghostly sightings.[8][14] > > > 19 hertz is a very low frequency...elephants and hippo's can actually generate these sounds, but it's generally relegated to large creatures. Some whales as well. [Answer] Just random thoughts: You don't have to focus on the intensity/volume of sound to achieve these effects. Pitch and modulation can have dramatic effects on all manner of things, ultra-low frequencies can stop your heart (urban legend, but not outside of the realm of possibility if framed correctly), high frequencies can disrupt your balance, soundlessness can drive you insane, irritating sounds can do that as well: It is easily imagined that the right combination can do any number of delightfully nasty things. High intensity sound is fairly easy to detect and block, and it is self limiting: If you do it too often to break your prey's ability to hear. Once you've deafened the nearby prey, they can fight back effectively. Also... frequency specific attacks would logically evolve with an immunity to them, though volume based attacks COULD do the same, the intense physical resistance a creature would need to use them (at human scale, I'm thinking about not just somehow protecting the hearing, but the bone and organs from presumably very intense bursts of vibration). [Answer] The Pistol Shrimp uses an oversized and specialized claw to create a sonic blast which can stun or kill its prey, and I believe I read dolphins or porpoises using sonics to stun fish as well. Underwater may not be your goal, but sonics do get used by exixsting lifeforms so now its just research and adaptaion to fit your requirements. [Answer] Sperm whales hunt giant squid; How the whales manage to subdue such able prey has been a mystery. One hypothesis, proposed more than 20 years ago, speculated the whales used powerful ultrasound shrieks to knock their squid prey senseless before scooping them up. Like bats and dolphins, some whales use ultrasonic clicks to find prey and navigate. The basic premise is that that, since sound travels faster underwater, that a beam of sound(echolocation) that is narrow enough could kill in the same way shockwaves do; by rupturing the organs of the animal. A few helpful links of weaponized echolocation; 1. <http://www.livescience.com/7297-whales-attack-squid-mystery-deepens.html> 2. <http://www.science20.com/squid_day/do_sperm_whales_use_sonar_stun_giant_squid> [Answer] So this is way out there, and the chance of such creatures existing is so unlikely I don't even want someone else doing the math, let alone having to do the math myself. Let's say this is just a “LITTLE” bit contrived. I can imagine two ways for this to work, that don't rely on concussive force or infrasonic something. One method absurd and one plain crazy. I let you decide which is which. 1. Sensory overload occurs when the conscious mind is overwhelmed by stimuli. One way to do this is sound. But seeing as sight trumps all other senses in perception. It would need to be an animal or animals that lives and hunts in the dark. To overwhelm the brain you need the veritable big brother plus the grandfather of cacophonies of different and disharmonious sounds. So I'd say a cave dwelling, carnivorous swarm of beetles. They'd need to be able to produce malleable sounds like crickets maybe plus in a cave you get the echo to multiply the sounds. I know that a swarm would just rush you and eat you, but that wasn't the question. Just for reference sensory overload can lead to a wide variety of effects from mild irritation to fainting. Seriously its beetles now idea if that would work on a beatle, how much memory do they have to be overloaded. 2. It is neither a quick, nor easy method saying nothing about the likelihood nor feasibility. Hypnotherapists say that around 25-30% percent of humans can't be hypnotized. The remaining humans range from easy to I'd rather climb the Everest. Sound alone can induce trance states in two ways I know of: By recurring monotonous sound like waves, white noise or red noise and lowering the heart rate awareness etc. this way until you got one hypnotized dinner. Or by two different frequencies of tone that don't disparage too much. For example hit the right ear with 500 hertz and the left with 510 and the brainwaves of the listener will mimic that 10 hertz difference sink the guy into trance. Bon appetit. No idea how either of those to work as part of animal, but I couldn't come up with another method to incapacitate someone with sound alone. Unless you find an animal that can play music then if got a third crazy way to do this. Can't hypnotize anything without subconsciousness, so much for self-defense. 3. Music can influence the heartbeat, which can lead to low blood pressure, which causes the brain to be underfed with O2, which in turn lets you faint. Made something else but music would do the trick here. I couldn't find anything where it did though. Don't know maybe they can plug their ears somehow if animals are even effected by this. [Answer] Killer whales use resonance to upset herring, and then a tail slap to stun them in this [BBC wildlife show (Oceans)](http://www.bbc.co.uk/nature/life/Killer_whale#p00jz1cs). My physics isn't good enough to say if what the whales are up to can be done in air. Alternatively, could your sonic attack be the biological equivalent of a flashbang grenade? A bombardier beetle chemical attack. Spit or throw something at a target. [Answer] I would suggest one of two variations, 1. Similar to a frog's air pouch, it could produce a large amount of air and force it through an opening, similar to a human throat. It can control the throat muscles, reducing or increasing the air flow to manipulate the pitch and volume of the sound, thus creating a 'screech' or 'him.' This can cause a variable effect on the target by using ultrasonic or infrasonic effects. The 'screech' could liquefy the internal organs of vertebrae, whereas the 'him' of infrasonic would disturb the liquid in a body causing the effects of nausea and a variety of effects on a being; 2. Alternatively, it can be a crustacean where again it utilizes an air pouch but has holes in certain places of its' shell to which it can manipulate a 'whistle' at certain pitches to disorient its' target. I have no degree and barely understand the science behind sound manipulation, but I'm fairly intellectual and have thought about similar situations myself, thus the answers I've given. Please forgive me if I've overlooked something. ]
[Question] [ Another question based off of this one [here](https://worldbuilding.stackexchange.com/questions/8772/can-a-nonspherical-planet-exist-and-can-it-be-habitable). Let's say on a cube styled Earth-like planet, there was a similar race to humans. If the differences in the planets were minimal (besides, you know, the whole cube part), how would the two civilizations change and grow (compared to each other)? [Answer] Assuming the cube world is the same as from your previous question things would be very different. The edges of the cube are mountains so high that they are literally impossible without the magic you added to keep them there. This would create six realms that are, essentially, totally isolated from one another. **Six worlds, one planet.** A sentient race living on one of the faces would need to develop mountaineering-space-suits or have some incredible mining abilities before they could get to another face of the cube. It's possible that life could make it to all the faces via single celled organisms through groundwater fissures. After that you would have six faces that take possibly very different paths of evolution. To view another face would be to view something quite alien. According to Karen Masters, an astronomer at Cornell, the [oceans would be in the center of each face](http://curious.astro.cornell.edu/40-our-solar-system/the-earth/climate-and-weather/70-how-would-the-weather-on-earth-be-different-if-it-were-a-cube-intermediate), not flowing over any of the edges. She further describes the weather differences depending on which axis your cube is spinning on. ![enter image description here](https://i.stack.imgur.com/AFvH2.jpg) The gravity of such a planet would make walking around on it strange indeed. Each face would seem like a massive bowl, surrounded by mountains. The edges would be so high in fact that they would be sticking out of the habitable atmosphere. [From Jesse Berezovsky](http://www.quora.com/If-the-world-were-a-cube-how-would-gravity-be-different), Professor of Physics, Case Western Reserve University: > > Interestingly, we see that the large majority of the cube's surface is outside the atmosphere. Since humans can survive only at about 10km above the earth's surface, this means that the habitable land on the cube would be a narrow ring around the oceans, about 10km wide. > > > ![enter image description here](https://i.stack.imgur.com/qZLVu.gif) And from "[The Physicist](http://www.askamathematician.com/2011/05/q-what-would-earth-be-like-to-us-if-it-were-a-cube-instead-of-spherical-is-this-even-possible/)" at <http://www.askamathematician.com/> ![enter image description here](https://i.stack.imgur.com/kwKzU.jpg) > > The vast majority of the Earth would take the form of vast, barren expanses of rock, directly exposed to space. If you were standing on the edge of a face, and looked back toward the center, you’d be able to clearly see the round bubble of air and water extending above the flat surface. I strongly suspect that it would be pretty. > > > So, our two civilizations would be very different indeed. Though the cube-worlders would probably have something like the phrase "all the corners of the Earth" though it would mean something quite different. [Answer] Assuming you can build those huge mountains on a planet without melted mantle. (Because it would not be possible on a planet with melted mantle - mountain material would melt under own weight, and sunk into crust). Planet needs to be manufactured that way. **My assumption for "Earth-like" is: planet has enough water to cover about 70% of the livable surface.** There will be some irregularities (not a perfectly laser-manufactured cube), but irregularities will be small - hills here, islands there, to make planet more interesting. Edit: Apparently it would take a bit more water than I expected to submerge the ridges. If you add enough water to submerge ridges, my answer is correct. If not, then it is not. Pick what you want. **it will still make little difference.** Yes, your planet would have 8 huge peaks, out into stratosphere, **or even out into space**. Yes, there would be huge long ridges, affecting the winds. But that ridge will have also deep valley between peaks, and people can walk around from one "side" of the cube to another in the middle between peaks. Over high ridge, or over sea - depending of how much water your planet has. Gravity will be weird, because even if surface is straight, gravity rounds down. So walking toward the corner peak, it will gradually become steeper and steeper, becoming 45% close to ridge. With enough water, these ridges would be partially submerged and allow travel between sides. With less water, they would be just tall mountains (but not as tall and corners of the cube). I don't have time to calculate, but my gut feeling is that middle of the ridge would be below average distance to planet's center ("sea level"). Yes, **some parts of science will be easier to research. Rocket sled launcher would be easier to build,** so space exploration will be bit easier. But if you ignore difference in climate caused by huge mountains, and different topography of the ocean currents, there would be very little difference, if cube was made with earth proportion of lands and waters on the surface. To get **more different climate you may tweak rotation axis, and tilt relative to ecliptic.** * If axis goes through mountain peak (corners), all sides have exactly same climate, with another mountain ridge around equator (best site for rocked sled launch). * If axis goes through center of sides (faces), you have two "polar sides" and 4 sides with same climate. Sides still could have climate changes, depending on the tilt. But those **differences in climate would be cause by tilt, not by planet having the shape of a cube.** So result will depend on how much water you have on such planet. Add enough water, and you can travel easily from side to side. Make planet dry, and travel between sides is over stratospheric mountain ranges. They will be smooth, no glaciers to scar them. Seems that planet shaped as cube creates very little livable area. Seems that [ringworld](http://en.wikipedia.org/wiki/Ringworld) gives you more living space for same material. And if you want to divide civilizations, you can always add a ridge. [Answer] The answers to date presume this is a cube of (roughly) uniform composition. But it's clearly an engineered world, so it will be built to work more effectively. Imagine it's hollow. Six huge squares. But, need gravity. You can have hyperdense material in a thick circle inscribed on each face. The corners are left light and mostly decorated without living geological processes. The dense plates require less total mass than a solid sphere for the same surface gravity since you are very near to all of it. It will fall off rapidly as you rise off the surface since the distance squared is measured from 100 km underground, not 4000 km to the center. *And it's hollow!* The amazing stuff it's made of is seemimgly indestructible and hyperdense. The skin forming the corners is very thin, like a couple meters tapering to 1 cm at the point, plus some thicker ribs. The face features a lens shaped [gravatus](https://en.m.wiktionary.org/wiki/gravo#Latin) plate a couple hundred km in thickness, somewhat concave (deeper at the circumference) to keep the gravity [normal](https://en.wikipedia.org/wiki/Normal_(geometry)) to the flat face. Leaving the edge of the gravatas plate to continue to the edge of the face will look flat, but *feel* like a rise that quickly goes to near vertical, since all the gravity is behind you. There are access hatches and maintainance corridors beneith that some residents may find, even corridors to connect the faces. In the rock below the topsoil but above the gravatas plates would be machines. It "gardens" from time to time to undo erosion and just to randomly rework the habitat. Stores of normal matter and a moon's worth of minerals are stored in the hollow, so it can throw up mountains and add bedrock. --- Let's get crazy now: the sun does not follow a constant axis, which keeps some faces as arctic. The sun track shifts to give everyone daylight. It would be hard to podehole the cube and move the axis of rotation around, so make the orbit interesting instead. Put the cube in orbit around a neutron star, and that has a companion star (the sun) with the orbital plane 90° relative to that. And the cube rotation axis (through the corners) is orthogonal to both of those. Hmm, that doesn't work at short enough time scales (weeks, not years). So, give it 2 suns, 90° apart as seen from the cube. One is centered on the northern 3 faces and invisible to the southern, and vice versa. I'll see about drawing some sketches later. (See [followup question exploring this idea](https://worldbuilding.stackexchange.com/questions/21510/celestial-arrangement-for-the-cube-world)) The K-II civilization that built it would stock it with interesting life, just as we would fill a garden pond or terrarium. If that civilization still exists, they would be watching. [Answer] It is doubtful whether life 'as we know it' could develop on such a planet. To start with there could be no erosion of the surface, because this would destroy the integrity of the cube. Therefore no soil. Or if gravity was (as suggested) perpendicular to the surface, the pull of gravity on the corners would be in two directions at once, both parallel with the surface. A new Newton would need to be invented for this. If indeed the gravity was 'normal' ie towards the cube centre, then four, or six, different worlds might develop, starting at different times and going in quite different directions, evolutionarily speaking. Alternatively, each face of the cube could have its own God (or Gods) who arranged things to his, her, or their wishes. Whether each of the Gods would be omniscient or omnipresent is a question for later. [Answer] Simple answer? Any way you want it to. There've been a wide variety of civilizations on Earth. Any of those, for example. And that's not even getting into whether or not you've evolved humans. You could evolve any type of plant or animal, and get a wide variety of civilizations. ]
[Question] [ ## Primary question What is going on with the atmosphere that the world is so gloomy and dark? ## Information I have had a low-magic fantasy world I have been wanting to solidify for a while now but previously dismissed the idea as too hand-wavey until [this answer](https://worldbuilding.stackexchange.com/a/102427/45157) to a question popped up (the answer basically says: if you only block a lot of *human visible light*, plants can still live while it looks super glum). I have looked around but didnt find something already posted that got me where I wanted. I found these ones [here](https://worldbuilding.stackexchange.com/questions/18264/how-dark-can-a-habitable-planet-be), [here](https://worldbuilding.stackexchange.com/questions/97432/could-i-make-this-dark-and-eerie-world-possible), and [here](https://worldbuilding.stackexchange.com/questions/30143/where-to-find-shelter-in-a-cold-dark-world-at-war) about dark/hazy worlds. Here are the criteria that I want to meet on this dark world **Criteria** * The world is always darker than earth, but still has a visible day/night cycle (think full moon versus new moon but a bit brighter). * It is very cloudy and drizzly but its dimness would (likely) come from a dusty/hazy atmosphere even when it is not overcast. * The rain is still drinkable with minimal effort even if bitter. * It needs to be warm enough to rain (above freezing) at least the majority of the year if not all year. Chilly is fine, snow and ice is less fine. * There is still leafy plant life in addition to more mushroom-eqsue plants ## Clarifying Details I am fine with magic or some magic going into it, but I don't want the world to work entirely "because magic". If only some of the light spectrum is blocked then the world should still be dark while maintaining these characteristics and its plausibility... I think. What can I do with the atmosphere or world that has at least some science that will mess with a normal range of vision while not having toxic rain and keeping at least slow growing leafy plants? [Answer] **Ring around the star.** [![Ring around Fomalhaut](https://i.stack.imgur.com/H3kOs.jpg)](https://i.stack.imgur.com/H3kOs.jpg) from <https://commons.wikimedia.org/wiki/File:Fomalhaut_B_entire-Hubble_Telescope.jpg> Just as a planet can have a ring around it, so can a star. If you were in the same orbital plane as the ring and it was between you and the star, it would shade you. Consider the situation of the outer shepherd planet in this schematic of the ring around the star Fomalhaut. It is shaded by the ring. from <http://www.solstation.com/stars/fomalhau.htm> [![schematic of Fomalhaut ring](https://i.stack.imgur.com/E2w4m.jpg)](https://i.stack.imgur.com/E2w4m.jpg) This is nice for your scenario in that * You can have it suddenly get darker if you like. The ring was formed by a dissolution of one of the inner planets in the system. * You have no constraints on the atmosphere of your own planet: the shade is cast by far away stuff. Degree of shade might vary with the density of the interposed ring, which can change as ring and planet orbit. * What would this look like from the perspective of the planet? I am sure there would be twinkling chunks and haze in the sky at all time. * You planet can have one pole protruding beyond the shade of the ring. Here one can still see the sun rise. --- ADDENDUM - Ring are thin, I hear? Too thin to shade? Saturns rings are thin compared to Saturn or compared to their width, but we are talking about a ring around a star. How thick is Fomalhaut's ring? <http://www.dailygalaxy.com/my_weblog/2012/10/the-strange-planets-of-fomalhaut-a-spectacular-alien-star-system.html> > > The original ALMA research shows that the ring's width is about 16 > times the distance from the Sun to the Earth, and is only one-seventh > as thick as it is wide. > > > So 16 / 7 = 2.2: the ring is only as thick as double the distance from the Earth to the Sun, which is 146 million km x 2 or 292 million km. The diameter of the Earth is 12,742km. I think the Earth would be able to find shade from a ring of this size. [Answer] I can envision a world that matches most of what you describe, yet provides some unique opportunities for story telling. Start with a planet with a dense, organic rich upper atmosphere, that becomes mostly transparent near the ground. This is a reasonably accurate description of the atmosphere of Saturn's moon Titan. At mid day, at ground level on Titan, the illumination is about 1000 times less than a sunny day on Earth, or about the same as 10 minutes after sunset. So it's very dim, but bright enough for a human to navigate. If an intelligent species evolved here, they would certainly develop eyes adapted to this light level. Next, there's the issue of plant life. Consider, due to the dim illumination, there is very little plant life on the surface. However, the upper atmosphere is teaming with various photosynthetic microorganisms, akin to the phytoplankton in our oceans. They convert carbon dioxide to oxygen, thereby adding oxygen to the atmosphere. Also, when they die, they fall though the thick clouds to the ground below. There are small animals that eat this thin organic layer (of dead phytoplankton), so become the base of the food chain. So you have a dimly lit planetary surface, with a few slow growing plants, teaming with animal life. Any intelligent life would have no idea that there was a whole universe beyond the sky. See James Blish's *Surface Tension*. Info about Titan's atmosphere and illumination level: <https://en.wikipedia.org/wiki/Huygens_(spacecraft)> Summary of James Blish's *Surface Tension*: <https://en.wikipedia.org/wiki/Surface_Tension_(short_story)> [Answer] Perhaps your planet is surrounded by a thick dust field. The dust field is thick and surrounds the planet, and is approximately 5km thick. > > The rain is still drinkable with minimal effort even if bitter. > > > The dust is just on the edge of orbit but far enough away that it wouldn't ever descend onto the planet and cause problems with the environment. I'm not an expert but I would imagine that this would block a fair amount of light from entering the atmosphere, whilst still providing adequate enough sunlight to allow for normal life cycles to exist. **But why is there a dust field?** The space around your planet is or was a minefield, asteroids are or in the past (few thousand years perhaps) colliding with each other and the remaining fragments ricocheted off into deep space or down onto your planet (This could open up for some extra story telling, my thinking would be either an explanation for a particular species of mushroom or an event that the locals celebrate annually). Now all that is left are small rocks and a lot of dust just orbiting the planet indefinitely. **Edit** To better answer your question, if you did want to add a little bit of magic, perhaps there is a spell/magic barrier that prevents the dust from entering the atmosphere. I feel that this would better explain why the dust is stuck orbiting the planet rather than being just on the edge of orbit, as that doesn't sound particularly scientific. [Answer] I'm going to suggest that the star it's orbiting is near the end of it's life, or it's just a slow burning star. <https://astronomy.stackexchange.com/questions/6210/are-there-stars-that-dont-emit-visible-light> <https://www.quora.com/Why-do-stars-emit-visible-light> You might need to have a planet that's closer to the star to inhabit to get enough warmth, UV (for plants), and other considerations. You could also have a moon that is tidally locked (or similar) to keep the planet in an eclipse state. Maybe the moon wasn't always in that position, but it orbited the planet in the correct direction and eventually slowed (or sped up) due to the gravitational force of the sun so that it is "locked" in one spot between the sun and the planet. This could be something like a Lagrange point between the Earth and the moon, or simply a spot where the speed of the moon matches the speed of the planet in it's orbit. <https://www.space.com/30302-lagrange-points.html> Another idea is that it's a hot planet that has lots of humidity, causing fog and clouds. Anyone who has been in a sufficiently foggy area knows that fog seriously reduces the amount of light available to see by, and clouds are known for their light blocking capabilities. The "Coldfire Trilogy" by C.S. Friedman gives the impression that it is nearly constantly darker than Earth due to a combination of high humidity and maybe volcanoes. This is also a magic realm, which was colonized from Earth and stranded due to misfortunes which I won't get into as they would be spoilers (I think). It's a good series, so you should enjoy that research. [Answer] Debris in your planets orbit or atmosphere are good ideas. Moon(s) blocking sun light most of the time. There is a question of what level of technology exists here. The problem here is how they got to this level of technology with no or little sunlight. 1. Aliens who destroyed their own world and moved here. 2. Planet existed in full daylight in the past, but now the star has dimmed significantly. 3. Maybe the sun is just forming, and it hasn't reached full power yet, maybe its another 100k years or more till full power. There are red and blue grow leds specifically designed to allow plants to grow. An advanced enough civilization could basically light different areas of the planet they need lighting. You could literally light entire farm fields with leds, and one such a planet even more advanced lighting techniques might exist. The problem is to maintain the planet in semi-warm environment, even with something blocking the sun/star. 1. If you were close enough the heat of the sun would still reach you, but I suspect you would need to be a lot closer. 2. Either that or rewind the planet to a time where lava was only 10's of feet below the surface of the planet. If you found the right depth of lava the surface of the planet would definitely be warm/hot and remain that way for long periods of time. Even 100,000 years is nothing in galactic terms, and your whole society could evolve and become extinct in that amount of time. If the planet was high/low enough compared to the star only the pole of the planet would get direct light. Very careful placement could result in most of the world not getting much sunlight. However, the north/south pole depending on elevation would definitely get full or nearly full daylight. --- Maybe your whole world is an alien experiment. They have erected a force field around your planet which block most of the light most of the time. 1. Scientific experiments to see how life develops under these conditions. 2. The aliens are just plain mean and like messing with lower civilizations. 3. Bored and need something to do, so they bother others like Q on Star Trek. 4. Prison planet. (all lefties go to prison per Dilbert episode) or similar. [Answer] It could possibly be a thick atmosphere. If it darkened over time gradually then the plant could evolve or if it was dark from the beggining then any plants still existing would have the ability to survive (natural selection). [Answer] Ozone layer. Make your planet to circle a neutron star, O giant or other very hot star, and the high level of UV radiation would ionize the atmosphere, making ozone and nitrogen oxides that blocks out visible light on the planet. However, since the star radiates in primarily soft X-rays that penetrates this layer well, plant life on the surface can use this radiation for photosynthesis. Think things like melanin or other types of radiotrophic synthetic process. Since the star make little radiation in the visible spectrum(to not boil or scorch the planet), you will have an overcast sky with the ionized ozone layer, little light from both the star and from the absorption of the atmosphere, surface plant life which don’t use visible wavelengths and all the things you can get for your requirement. Add in magnetic fields and particles that comes with the hot star you get magic-like abilities, for the human race, they just arrived off-world, therefore does not have eyes that can see the X-rays like other life on this planets can, giving a dark overcast impression. [Answer] The 'dark ages' are called the 'DARK ages' for a reason, They started with an event that, literally, put the earth into darkness. Something was blocking out the sunlight. It is hypothesized that it was a volcano that created a thick dust cloud around the earth. See [The Dark Ages Were Caused By Two Enormous Volcanic Eruptions](https://motherboard.vice.com/en_us/article/ezpv7n/the-dark-ages-were-caused-by-two-enormous-volcanic-eruptions) and [Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages](https://link.springer.com/article/10.1007%2Fs10584-016-1648-7) for a scholarly article. > > Volcanic activity in and around the year 536 CE led to severe cold and > famine, and has been speculatively linked to large-scale societal > crises around the globe. > > > Also see [They really were the Dark Ages](https://www.nature.com/news/2008/080311/full/news.2008.665.html) In London, England, the 'pea soup' fogs that blocked out the sunlight were due to particulate pollution from burning dirty coal fires. So there are a few possibilities in your world. I would suggest that there are huge coal or other organic or carbon deposits, that have been set on fire and have been burning for a very long time. These would produce a huge particulate smoke cloud that covered an area. Your question does not specifically state that this has to be planet-covering, just covering 'your world'. During the Dark Ages, their 'world' was Europe. It also does not give a time frame for this effect. A second option would be continuous dust storms. A weather pattern that produced constant high velocity upper atmosphere wind patterns. The wind energy would have to come from some extreme temperature differential. Perhaps a tidally locked planet with a thick atmosphere would produce constant convection air currents from the hot side to the cool side. Since the rotation of the planet would be very slow, there would be no or minimal Coriolis effect. A third option would be continuous volcanic activity on the planet. An earthly example would be [Two centuries of continuous volcanic eruption may have triggered the end of the ice age](http://theconversation.com/two-centuries-of-continuous-volcanic-eruption-may-have-triggered-the-end-of-the-ice-age-83420). Also, apparently Io has permanently active volcanoes. ]
[Question] [ I'm developing a world in the near future where a start-up company develops an artificial womb. Now well-off people could grow their children from their eggs & sperm. My story is about couples that can't conceive and serve as test subjects of the program. Since I read that human babies are born [prematurely](https://blogs.scientificamerican.com/observations/why-humans-give-birth-to-helpless-babies/) is it realistic to extend the gestation period to 21 months thus having a more developed baby? My setting works better if the 99% feel that technology allows the wealthy to order their children, while the not so lucky women risk their health or have gaps in their careers. **Explanation**: The setting is near future, something like the next year or two. The company ***barely*** managed to mimic what mother nature is doing, and is still very vulnerable to proving that their technology results in healthy ***normal*** babies. I assume that no giant breakthrough in genetic engineering occurred that will enable us to create designer babies. [Answer] To pile onto what @kingledion said, going more than 9 months is actually *dangerous*. Most doctors will demand a woman get induced if the baby's not coming by two weeks late, because anything beyond that *significantly* increases the chances of still birth. Other than that, while 1-year-olds aren't exactly geniuses, a 1-year-old who's been learning *outside* the womb is going to be crawling/walking, gesturing, grabbing, babbling, and will know many words that they hear. A 1-year-old who's just been born is going to be *way* behind developmentally, and may never be able to catch up. Additionally, [visual development](http://www.aoa.org/patients-and-public/good-vision-throughout-life/childrens-vision/infant-vision-birth-to-24-months-of-age) is *highly* dependent on actually being able to see. This is one of the reasons why doctors will try and correct visual problems (cataracts, squints, etc.) as soon as possible, even if it requires somewhat dangerous surgery. "Ah," you say, "my womb will let them see out." The problem with this is, even if they can see, they need things to look at. And even if they have things to look at, they need to be able to *interact* with those things for the proper neural connections to form. How do we know this? Experimental studies involving sewing kittens' eyes shut, keeping them in a box for several months with only vertical stripes, and controlling whether they can move or not. [Answer] While you are correct that humans are born a bit early in their development (compared to animals like deer that can get up and run within hours of birth), simply leaving a fetus in an artificial womb would have issues. Post-term fetuses increasing in size run the risk of out growing the placenta (it drastically slows growing around 37 weeks or so), defecating in their own amnionic fluid and inhaling it (known as meconium aspiration syndrome), wrapping themselves in their umbilical cord as they become more active, and potentially out growing the fetal circulation pathways necessary to bypass the lungs. The foramen ovale and ductus arteriosus may not be sufficient to supply blood for a large fetus. Although massive infants of 20+ pounds have been born, those infants may suffer from significant health issues later in life, usually because the mother had gestational diabetes. A longer gestational period may help somewhat with infant muscle tone, motor coordination, and digestion, but there will be the risk of losing protective reflexes (mainly related to swallowing/breathing) before the baby learns the proper techniques in order to feed safely. A few more weeks in the artificial womb probably wouldn't be an issue and could lead to a baby a bit larger, more capable of sleeping through the night and feeding more at a time, but of course if it ISN'T feeding in utero it won't be able to develop these capabilities. Alas, simply letting a fetus hang out in the womb for a few more months won't get you the equivalent of a 3 month infant. They won't have the same feeding capacity, lung volume, muscle tone, visual/auditory acuity, etc. Perhaps if they were kept suspended in fluid in a clear womb where they could see outside and had lots of room to move around they might have some of this early development but ultimately I don't think there would be much benefit versus the risks for placental insufficiency, meconium aspiration, and having a big baby that doesn't have a stomach size and feeding skills to match. [Answer] Stick with 9 months, given this is real-world humans. The limiting factor is that the baby's head has to fit through the mother's pelvic girdle, which is a ring of bone. At the current nine-month human gestation, this is almost always possible, but the safety margin isn't huge. Babies who are born late continue to grow and can readily become too large to fit, which requires an emergency Caesarean operation. This is not something that you want to make standard practice. [Answer] No it is not realistic, the shape of a baby is like that because it grows inside uterus: if you keep him more time than needed in a restricted space he could grow deformed or with some malformed organs, the human body works by staying about 9 months in uterus and then by staying a like on "the ground". Bones grow in response to gravity, if you grow in something like "floating fluid" the body will grow in a different manner that could cause at least social problems and eventually health problems. Also mother attentions are necessary for correct mental grow, all cares are important to a baby. [Answer] Evolution favoured nine month because a newborn that was significantly larger and further developed would be stuck inside, because it's mother belongs to a species that has evolved into walking upright etc. No problem for you. But: Human newborns are not exactly underdeveloped, or only if you compare them to, say, horses or giraffes. It's true for the bone structure, they are pretty small, for the reason given above. Otherwise they are rather overdeveloped *for their age*. Respiratory, immune, digestive system, all working (more or less). It would surely be possible to adapt a lot of this, because it all happens in close interaction with the mother's body. Question is how, and how high the price would be to find out. An then some parts might even demand some genetic engineering. In which case they'd arguably be no longer human. ;-) [Answer] Because homo sapiens sapiens had a gestation period of 9 month for milleniums, everything (brain, muscle,immunie system, digestive system) is calibrated to start working properly around 9 month. Any shorter or longer gestation would cause more problems than it solves UNLESS you modify our DNA. However the OP ruled that out so I think the benefits of >9 month gestation if there are any are dwarfed by all the complications it ll cause. [Answer] the limit of 9 months is generally due to head-to-pelvis ratio. escaping that trap implies that these children could develop larger heads (and larger brains). the obvious advantages are either increased intelligence or larger overall size. that said, if you have the technology to increase brain size while growing an embryo into a fetus, you probably also have the technology to increase brain size after the fetus starts breathing (thereby becoming an infant). [Answer] Everything else being equal, a human fetus in utero for 21 months will be dead. So, it is *not* reasonable. How could you make it "reasonable"? Slow down the process by a factor of 21/9, obviously. That would require changes in the infant's genetic code or some sort of (wave hands, queue in the smoke and mirrors) stasis (low temperature hibernation?). Why would we want to do that? Well, only reason I can think of is to either do a quality control of the kid's genome, or to add/subtract to it. Based on the little I know about neural development, this would be a very very bad thing for the kids brain...again, unless something was done to 'fix' the deficit caused by an enormous decrease in stimuli starting at 9 months. Keep in mind that the brain is undergoing a gigantic construction project at and in the months immediately after birth and without the "right" stimuli, the resulting structure will not have been constructed correctly. I can't really see any good reason that this could be useful. 21 months is just waaaay too long. Also keep in mind that at some point, a placenta just will not be able to keep up with the body's demand for nutrients and oxygen... and guess what? that happens at about 9 months. So, even if you slow it down, you shouldn't expect a more developed newborn, just the opposite, you'd expect a LESS developed one (since it will necessarily have been deprived of critical nutrients). [Answer] I can't understand why a baby would be less developed if it stayed incubated longer. Nature has some level of intelligence and ability to adapt to its environment. If no placentas have been given a chance to prove that they are perfectly capable of housing babies in a womb for 2 years, then how can it be said that they are not still able to provide? So long as the mother is eating etc, maybe a more aged placenta becomes stronger with time and more efficient because it has gotten used to the body. Thus giving birth to a baby whose lungs are developed possibly neck, the rest will incubate on the back burner until it actually breathes air. In the meantime your drinking water etc no reason why the amniotic fluid fluid cannot replenish itself. Low amniotic fluid is already been deemed a scam. And of course not all humans development and intelligence is the same otherwise we would all be Bill Gates so the abilities if a baby in some cases can be exceptional, though rare inded . ]
[Question] [ In my world I want to create a really deep underwater science facility to conduct weird and unethical experiments in. But I think to myself: How deep could I take such a building? Does it become easier to withstand ocean pressure with a larger building because you can increase the size and strength of structural components? Or does it become harder because its more surface area for the ocean to attempt to crush? Or does size not matter at all and it all depends on how the structure distributes the pressure? Bonus points if you have suggestions for maximizing the depth of an office building (or larger) sized underwater facility. [Answer] Your structure would definitely need to be spherical, since that shape supports so much more pressure than hard angles. (The human part of the bathyscaphe which descended to the bottom of the deepest trench in the ocean was the little sphere at the bottom of the picture. The rest was gasoline, water and iron to regulate buoyancy.) Since we've gone to the very bottom of the ocean, you can thus put your underwater lair as deep as you want to. <https://en.wikipedia.org/wiki/Bathyscaphe_Trieste#Design> > > To withstand the enormous pressure of 1.25 metric tons per cm² (110 MPa) at the bottom of Challenger Deep, **the sphere's walls were 12.7 centimeters (5.0 in) thick** (it was over-designed to withstand considerably more than the rated pressure). > > > There are many practical problems, though, with building and living in such a pressure vessel: 1. you're going to need a **lot** of steel, 2. building it will not be a secret, 3. towing a monstrous, and monstrously heavy, round office building into the deep ocean will be, to put it mildly, difficult, 4. you've got to keep the outside painted to prevent corrosion, 5. all the welds must be *perfect* (in the deep, water will quickly cut through any crack, rapidly opening it), 6. it must be powered, warmed, etc, 7. the crew must be fed, 8. it must be maintained. Best just to hand-wave the details. [![enter image description here](https://i.stack.imgur.com/g2P5K.jpg)](https://i.stack.imgur.com/g2P5K.jpg) [Answer] You can make the structure pressurized to match water pressure. Then you do not need to worry too much about structural integrity, and make it as large as you want. The cost is multi-hour (de)pressurization required while entering or leaving the facility. This could be a useful security feature as well: to prevent unauthorized access, and unauthorized departures. The movie DeepStar Six (1989) has an example of explosive decompression. Here is an [RL example](https://www.theguardian.com/careers/careers-blog/under-pressure-job-deep-sea-diver) of the setup necessary for an unauthorized diver to reach your deepwater facility. You can build it in pieces, but single large and round structure will have better volume/wall area ratio. It will cost a lot, so research should be extremely high-value, and do not plan any large open areas in there. It will be a submarine. Edit: I did mean to say that underwater structure has air pressure comparable to water pressure outside of it. I believe this can be done as part of [Saturation Diving](https://en.wikipedia.org/wiki/Saturation_diving): > > the divers live in a pressurized environment, ... [e.g.] an ambient pressure underwater habitat. > > > I still feel this is overkill for the goals. A better way to hide a secret lab underwater is to get a nuclear-missile submarine, and replace missile silos with labs and extra life support. It cannot go deep, but it can move around, it is designed to stay stealthy, and it can stay underwater for months. [Answer] Do you actually need it to be very deep underwater? If you just want it to be hard to find, you can place it in remote shallow water (well, not really shallow, but something like 100 meters deep). Somewhere near Greenland, or Antarctica would work, if you want to place it firm on the bottom. It's not like there are millions of scuba divers in these places. It might be better not to complicate the story with unnecessarily fantastical elements. Also take into consideration that you are underwater, so you need an earthquake inactive area if you build on the seabed. [Answer] That depends on how much you want to isolate that group of people from the surface population. To hide from the police 5 meters below water is enough. Or, really, 5 meters above is well, too. To sponsor a local police station would bring much better invisibility. If you want to escape from accident observation, you need about -500m, for to hide from the frequent underwater observations - 500m is about the reach of a man in a hardshell suit, something as <https://en.wikipedia.org/wiki/Atmospheric_diving_suit>. And under a place heavily used by ships - such place will never be used as a base for a bathystat or bathysphere. And bathyscaphe can reach everywhere, you should hide in the place that is dangerous for them. But seismical regions are even more dangerous for your construction. And if somebody really wants to find them - he will catch them at passing resources from the surface, even if you hide them in the mantle of the Earth. [Answer] The merit of having it underwater is that you don't leave tracks. However the engineering to supply deep underwater structures would be fairly obvious. There aren't commercial submarine freighters at this point. A better solution to not be blatantly obvious would be to have a submerged entrance to an underground cavern. Now you only need a supply vessel that can do shallow dives for short durations. Pick your location so you have multiple nearby ports. However it is far easier to hide something in the middle of a reasonably large city. Consider a cement plant. No one comments on heavily laden trucks running in and out. So hauling away the spoils of digging would be fine. Next door you have a warehouse facility. Again, 50, 100 semi loads a day is no big deal. Now you have 10 acres of floor space 500 feet underground. No one can hear the screams. ]
[Question] [ If the ground end of a space elevator was severed, what would the unfolding event look like from the ground? What would the movement(s) look like, and over what period of time? I’m assuming that it’s a “standard” space elevator: situated <= 20 degrees of the equator; diamond nanothread construction; “top” of the elevator in geostationary orbit; tethered weight at 62,000 miles above the Earth’s surface. [Answer] <http://www.spaceward.org/elevator-whatif> Where it breaks is fairly important. > > First and foremost, if the tether breaks, everything above the break-point will "fall" upwards, escaping into space. Since most of the dangerous environments are near the bottom of the tether, only a short bit will collapse back down to Earth. > > > A space elevator needs to be fairly light by necessity. > > The nominal (20 ton) Space Elevator tether weighs about 10 grams (a third of an ounce) per meter, and so over any square kilometer, the amount of material will be miniscule. > > > You definitely don't want to be climbing it when it happens though. > > Finally, there will 4-5 climbers on the tether. While the top ones may be able to remain in orbit, the rest will start falling towards the Earth. Manned climbers will of course have the ability to soft-land, and cargo climber might be allowed to simply splash down. > > > Above the break the counterweight would "fall" away from earth into a higher orbit. It probably wouldn't be terribly spectacular with a break near the ground. If you want something which is likely to fail in a really spectacular and devastating fashion (while also having an advantage over a space elevator that we could actually build one using known materials ) then you might want to look into a space fountain: <https://en.wikipedia.org/wiki/Space_fountain> I decided to try to work out the energy involved if there was a break very far up and most of the elevator fell to earth: In theory a space elevator might weight anything between 20 and 750 tons. I can't do the math for the real case where the mass is spread out all the way up it's length but I'll err on the side of "more disastrous" and do the math for all the mass being higher up near geo. Velocity at Geo = 3.07 km/s. (kinetic energy of 750 tons at 3.07 km/s) = 3.206×10^12 J (joules) which is about 95% of the maximum fuel energy of an Airbus A330-300 (97,530 liters of Jet A-1) or 1/20 of a little boy bomb. The potential energy of 750 tons falling from 35000km is larger but still only in the range of .05 megatons and most of that would be lost to friction with the atmosphere. Imagine spreading .05 megatons of TNT along a line 20,000 km long (still erring on the side of "more disaster"), that gives you 2.5 tons of TNT per km or put another way, 2.5 kg of TNT per meter. Imagine a stick of dynamite about 5.6 cm's thick that's 20,000 km long. That's the total energy of the falling space elevator. You wouldn't actually want that hitting you but if you were 50 yards away from the line you'd probably be fine. Again, that's even pretending no loss of energy to the atmosphere as it falls. A falling space elevator wouldn't be great but more along the lines of "it's bad to be hit by things falling on you" rather than "everyone nearby is very dead" [Answer] In Kim Stanley Robinson's book Green Mars (I think) he handled this in a lot of detail. The counterweight was explosively severed, and flew off, entering a solar orbit. The planet rotates, drawing the cable into a spiral. At first the cable touches down pretty softly, but soon it is being whipped into the ground at faster and faster rates. The shockwave from the first lap around the world did some damage, but the second wrap comes down at hypersonic velocities, killing everything a few kilometers north and south of the impact line. Whether this is representative of what would happen, or artistic license is unknown to me. But his books are well researched and contain a lot of hard science, so I assume it's been well thought through. *edit* sorry, I missed the bit where the OP said its the ground end being severed. [Answer] Obligatory [xkcd cartoon](https://explainxkcd.com/wiki/index.php/697:_Tensile_vs._Shear_Strength). Note that the space elevator does not need huge tension and ground anchors! Wikipedia indicates modern designs call for floating barges: hardly a substantial weight at the end. If you cut it near the ground, it would flutter around but not snap away. This is the right *fail safe* design. There are even sky hooks that don’t reach the ground at all. So this is a non-issue. [Answer] Let's say there say an explosion at the ground base and the tether was severed. Theoretically, it would just hang there. The simplest elevator doesn't really even have to be attached, it could just hang there, a couple of meters from the ground. However, most designs include the aforementioned counter weight to compensate for large climbing masses. Because of the counter weight, a ground level break would cause the whole system to shoot up away from the earth. Unless the counter weight was huge and tethered under tremendous strain (which I doubt) it couldn't leave orbit. The whole thing would just move into a slightly higher orbit then stabilize. Because this new orbit wouldn't be geostationary the bottom could conceivably crash into a mountain. But otherwise, it would be mostly harmless, the climbers on route could complete their journey (up) and not feel a thing. I'd like to think the engineers would be aware of this possibility and would have the ability to jettison some of the counter weight and hopefully have some thrust available to allow for them to reposition and reattach. Even if just left alone, atmospheric drag should pull the whole system back to nearly geostationary orbit (risking that dreadful mountain strike again). If the bottom of the tether is out of the atmosphere then, obviously, drag isn't a problem. Unlike Kim Stanley Robinson's novel, a break near ground level is a best case scenario. ]
[Question] [ What **artificial disaster** could **disrupt the orbit** of our planet? Not necessarily making it leave the Solar System, but maybe changing its trajectory around the sun. And by artificial, I mean that the cause **can't be an asteroid** or an object from outer space. Any ideas? I thought about a single, concentrated powerful atomic bomb explosion "pushing" the planet and disrupting its orbit, but I found that a little bit *cliché*. [Answer] # Lets find out how much energy that takes The energy of an orbiting object is the sum of its kinetic and potential energy and can be [expressed](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit#Calculation) by $$E = \frac{1}{2}mv^2 - \frac{GMm}{r} = \frac{-GMm}{2a}$$ where $GM$ is the gravitational constant of the sun ($1.327\times10^{11} \text{km}^3\text{s}^{-2}$), $v$ is the orbital speed (variable for a non-circular orbit), $m$ is the mass of the Earth ($5.972\times10^{24}\text{ kg}$) and $a$ is the semi-major axis of the Earth ($1.496\times10^{8} \text{ km}$). Plug this all in and we get $$E = \frac{-1.327\times10^{11}\cdot5.972\times10^{24}}{2\cdot1.496\times10^{8}} = -2.649\times10^{30} \text{J}.$$ Note that you go up by 3 orders of magnitude to convert km to m to get Joules. Also, the energy is negative because the gravitational potential of the sun is greater than the Earth's kinetic energy. If it were not, then the Earth would be at or above escape velocity and flying out of the sun's orbit. So lets calculate how much it would take to transfer to a different orbit. Instead of doing the Hohmann transfer calculation, we can just do the raw $\Delta E$ required. If we increment $a$ by 1, we get $a = 1.49600001\times10^{8}.$ Somewhere my high school calculus teacher is screaming about significant digits. Re-doing the energy calculation for this new, greater orbit, we get the same energy value, with rounding. But if we conserve all significant digits, we find that the difference between the two numbers is $1.77\times10^{22}$ joules. While this number is insignificant compared to the orbital energy of the Earth, it is very significant when compared to...well anything else that has energy. For example, Tsar Bomba's blast released about $2.1\times10^{17}$ joules, which means that even if *all* of Tsar Bomba's energy were directed into changing the orbit of the Earth, it would take about 100000 of them to move the Earth in orbit by 1 measly kilometer. The Chicxulub impact was $4.20\times10^{23}$, so that is more like it; but still not enough energy to produce more than a few km of orbital deviance. **Conclusion: It will take a lot more explosive power than we have managed so far to make any sort of significant change in the Earth's orbit. Any explosion that is large enough to make a significant difference in the Earth's orbit will be an extinction event, to say the least.** # Lets find out how much momentum that takes Now lets re-solve that first equation for $v$ to do some momentum conservation. The link helpfully boils this down to $$v = \sqrt{GM\left(\frac{2}{r}-\frac{1}{a}\right)}.$$ Assuming a circular orbit for simplicity so that $r = a$, I solve that as $v = 29.8 \text{ km/s}$ which is conveniently what [Google](https://www.google.com/search?q=orbital%20speed%20of%20earth&ie=utf-8&oe=utf-8#q=orbital%20speed%20of%20earth%20around%20sun) thinks too. The momentum of the Earth is then $mv = 1.779\times10^{29} \text{ kg}\cdot\text{m/s} $. So lets see what happens when we hit that with a Chicxulub. Lets say our impactor is going at a breezy 50 km/s, weighs 1e15 kg (a 5km radius, 2000 kg/m$^3$ sphere, approximately) and hits in such a way that *all* of its momentum is transfered to earth in the direction of Earth's motion. The added momentum is $mv = 5\times10^{19}$, so the new total for Earth is $1.7790000005\times10^{29}$. Resolving backwards through velocity and to semi-major axis of the orbit, we get an orbital change of about 80 meters. **Conclusion: Even if you were going to hit the Earth with something, you would destroy the crust, bore holes in the mantle and eradicate all life on it long before you move the Earth's orbit significantly.** # Extra final conclusion You are not going to move the Earth any significant distance with a single energy or momentum event while allowing anyone on it to survive. [Answer] [kingledion correctly points out that no single event can move the Earth without also basically destroying it](https://worldbuilding.stackexchange.com/a/66272/760), but that's for a single event. What if something on Earth was producing high thrust over a long period of time? Say a year? # Polar Thruster? Since the Earth is rotating, any long firing thruster on the surface will wind up cancelling itself out in the orbital plane. But we can move the Earth "vertically" relative to our orbital plane with a thruster placed at high latitudes, preferably at the North or South pole. Probably the South as there's solid land to work with. Due to the [Earth's axial tilt](https://en.wikipedia.org/wiki/Axial_tilt#Earth) of 23.4°, a stationary thruster at the South Pole firing over multiple years will lose some of its efficiency due to the angle, but it isn't going to matter because the numbers will get absurd. How powerful does our thruster have to be? Well, how fast do you want to change the Earth's orbit? What would you like the Earth's acceleration to be? What would it take to, say, move the Earth 10° "north" of it's current orbit over a year? The distance the Earth needs to travel is, roughly, the base of an isosceles triangle whose long arms are 1.52e8 km long and whose vertex is 10°. That's 2 x 1.52e8 x sin(10°/2) or 2.64e7 km. 26 million km. There's 3.15e7 seconds in a year, so we have that to move 2.64e7 km. How much acceleration do we need? We start with with d = vit + at2/2 and solve for a. v1 is 0 so it's just d = at2/2. Solving for a gives a = 2d/t2. If t = 3.15e7 seconds and d = 2.64e7 km we get an acceleration of just 5.32e-8 km/s2! A small acceleration over a long time adds up! Such an acceleration is so small only sensitive scientific equipment would notice. That might delay an investigation and allow a super villain to get away with firing a thruster at the South Pole for a year (though the people living there will probably notice). Might this work?! No, sorry. Now that we have the acceleration we need, how much force is that? F=ma. a is 5.32e-8 km/s2 and m is the mass of the Earth, about 6e24 kg. That's 3.2e17 kg km/s2 or 3.2e20 kg m/s2. kg m/s2 is a Newton. How much force is 3.2e20 N? Oh dear, that's a lot. It's the force of 1e13 Saturn V rockets. It's roughly the same as the gravitational attraction between the Earth and the Moon. What if it took 10 years? Looking at a = 2d/t2 we see that acceleration is the inverse square of time. If we increase time by 10, we decrease acceleration (and thus our force) by 100. Or for every order of magnitude increase in our thrust time, we get two orders of magnitude decrease in our thrust. If over 1 year we need 1e13 Saturn V rockets, over 10 years we'd need 1e11 Saturn V rockets. That's still a lot of rockets. Over 100 years it's 1e9 rockets. Over 100,000 years it's 1e3. ***To move the Earth 10° "vertically" in its orbit we'd need 1,000 Saturn V rockets burning continuously for 100,000 years.*** I think this illustrates why this isn't going to happen. Even though the needed acceleration is so small you wouldn't even feel it, the mass of the Earth is just too big, and the forces involved dwarf anything we can produce. # Paint One Hemisphere White, One Black? [Sunlight exerts a force on the Earth](https://en.wikipedia.org/wiki/Radiation_pressure) pushing it away ever so slightly. [Light that's reflected exerts twice the pressure as light that's absorbed](https://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_absorption_.28using_classical_electromagnetism:_waves.29). If the Earth [absorbed all its sunlight, it would exert about 570 N](https://en.wikipedia.org/wiki/Orders_of_magnitude_(force)). If the northern hemisphere were to become a perfect absorber, and the southern hemisphere are perfect reflector the Earth would experience a continuous net thrust "north". How would we do this? Ask Sherman-Williams. [![enter image description here](https://i.stack.imgur.com/btUQJ.jpg)](https://i.stack.imgur.com/btUQJ.jpg) How much this would be is beyond my calculations, but not more than 570 N or about 10 Saturn V rockets. So it's still not going anywhere fast. While this can have a measurable effect on small bodies like asteroids, known as the [Yarkovsky effect](https://en.wikipedia.org/wiki/Yarkovsky_effect) (thanks @IwillnotexistIdonotexist) it does not work on the Earth. Why? That pesky [square-cube law](https://en.wikipedia.org/wiki/Square-cube_law). Radiation pressure depends on the surface area of a sphere. As a sphere gets bigger its surface area increases as the square of its radius, but its volume (and thus mass) increases as the cube! So as you make a body bigger the ratio of it's surface area to its mass drops. That means less radiation pressure, less thrust, per unit of mass. [Answer] As kingledion points out the possibility of a man-made force on earth itself is next to impossible. My alternative may be outside your rules of "Can't be an asteroid or object from outer space" but it depends on how willing you are to stretch this. If you consider kingledion's point about changing orbits then we see that these depend on mass and radius. If the disaster were to involve a planet further out than earth and, depending on what rules you want your universe to have/stretch, less massive than earth then it may be more possible. If any orbiting object loses its transverse momentum (along the path of the orbit) it will fall in towards the host star (and it is further out so it can fall past earth on the way). So lets look at the possibilities here. [Pluto at its lowest momentum](http://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html) : $$M\_{pluto} = 1.3 \times 10^{22} kg , V\_{pluto,min} = 3710 ms^{-1} $$ Gives: $$P\_{min} = M\_{pluto}V\_{pluto,min} = 4.8\times 10^{25}kgms^{-1}$$ So you would need to hit it head on with something very massive to stop it entirely ($\frac{P\_{min}}{c} = 1.6\times 10^{17}kg $ where $c$ is the speed of light). However you needn't use Pluto and you needn't stop the object entirely. I don't know much about the future you're creating, perhaps you have some death star like ship which can travel at the speed of light to get from system to system. That would do it I believe (see below). If you had a large ship (perhaps a mining ship to make the excuse of why the ship was so heavy) crash into Pluto or some other fairly slow moving object then this could cause the effect you need. Perhaps a ship is rushed off badly repaired, the trajectory is badly calculated or some such and leads to it coming into the solar system head on with something. However it happens this method means we can have the huge impact needed but have it occur on another celestial object and so not wipe out those on earth. It does still require a huge impact though. * Based on [the death star being 160km across](http://starwars.wikia.com/wiki/Death_Star), a volume of $V = \frac{2\pi 160^{3}}{3} = 8.6\times 10^{6} km ^{3}$, lets say that is mostly empty space and 10% some material like steel with a density of $\rho = 7850 kg m^{-3}$ so our death star has a mass of $\rho V = 6.7\times 10^{19}kg$ obviously this is all just speculative. [Answer] An "artificial" disaster simply needs to be "being-made" (similar to man-made, but not species specific). In order to produce the energy required by kingledion's answer, there are two strong possibilities: One - an artificially produced, but sufficiently massive black hole or wormhole with gravitational qualities. Two - a planetoid-ship or other powered/movable object of sufficient mass to interact with the Earth (possibly using a slingshot effect) to shift the Earth's orbit. [Answer] Something that can push the earth out of orbit is if large parts of it's mass was converted into energy. Nuclear power that humans can produce isn't going to do it but [artificial miniature black holes](https://en.wikipedia.org/wiki/Micro_black_hole) are theoretically possible from high energy events subatomic collision events. They can possibly eat small part of the planet and then starve itself if no more matter is added. The black hole will then slowly release energy due to Hawking Radiation until they explode in a gamma ray burst. It doesn't actually take much since all mass in this situation is converted into energy from E= MC^2, it will only take about 10^11 KG of matter to converted into energy to make the 10^22 KJ of energy from @kingledion's answer. This is less than the mass of a small mountain. A event like this will likely take a long time for the black hole to gain and then lose the mass and might leave the side of the Earth that faces the black hole scorched due to energy released from the gamma ray explosion. ]
[Question] [ I'm designing creatures with naturally occurring white or pale grey irises and pupils so that it looks like their eyes are all white. What effect could this have their vision (colorblindness, light perception, etc)? Please note I'm not talking about leukocoria or eyeshine. [Answer] If the pupil is covered with material that is like [Muslin](http://en.wikipedia.org/wiki/Muslin) - a "sieve" with holes small enough not to be apparent - it would appear white from outside, but pass enough of light to still create a visible image; Muslin allows enough light through from the "bright side" so that a woman wearing a [veil](http://en.wikipedia.org/wiki/Veil) over her face can still see, but her face is obscured - similarly to [one-way mirror](http://en.wikipedia.org/wiki/One-way_mirror) except diffusing the reflected light instead of keeping it structured. Seeing in darkness would be severely limited but it would be far more immune to glare. That is not to say the being would need to be blind in darkness. The "veil" needs to be only opaque to human eyesight, that is, in visible spectrum. It could, for example, be completely transparent to ultraviolet and infrared, and related sensors in the eye could see with perfect sharpness - especially at night infrared would work quite well. So, yes, it's possible at cost of reducing ability to see colors visible to humans - but not blocking it completely, just "making it worse than human". A side effect to the "sieve" cornea might be that with the holes small enough, light would diffract. A very specialized eye (...inner structure entirely different from ours) plus a very complex neural "backend" could resolve the diffraction patterns into holographic image of the visible objects. That would not only result in superior depth perception, but also unlimit the sight range](["What do your elf eyes see" - what are the limits of sharp eyes?](https://worldbuilding.stackexchange.com/questions/11395/what-do-your-elf-eyes-see-what-are-the-limits-of-sharp-eyes)) making it possible to see objects at an arbitrary distance in smallest detail, only providing they are bright enough. [Answer] The pupil appears dark (not red-orange as the back of the eye which can be seen with careful inspection techniques) because light goes in but doesn't come out; it is the same as an absorbing surface. The eye, like the velvet lining of a telescope tube, doesn't want un-absorbed light bouncing around causing glare and fog. Our cornea blocks UV, which is damaging to the innards. It probably doesn't absorb UV (which is damaging!) but *reflects* it. So our pupils would appear as a white lenscap to sensors that used only those frequencies we don't. We don't have a name for color perception beyond the ones we see, but [Yperiodēs](http://www.forvo.com/word/%CF%85%CF%80%CE%B5%CF%81%CE%B9%CF%8E%CE%B4%CE%B7%CF%82/) or *ypio* for short (as primary colors are simple words) might be the perception of a distinct color in the 300-350nm range (see [wikipedia](http://en.wikipedia.org/wiki/Bird_vision#Ultraviolet_sensitivity) and primary [reference 31 Ödeen & Håstad "The phylogenetic distribution of ultraviolet sensitivity in birds"](http://www.biomedcentral.com/1471-2148/13/36)), and a secondary color where (in the UVS arrangements) where the short*est* cone overlaps the short up to the blue primary. That would be different from our *purple* which causes a closing of the color wheel. The color *ypio* is important for seeing mouse trails on the ground, spotting ripe fruit, and the patterns of plumage on the opposite sex. It's an eye-catching, important color; one that's worth considerable engineering difficulty to maintain as a sense. Our protective lenscap reflects *only* ypio and *absorbs* everything else, so that's the color it appears to them. An intelligent Psittaciforme would notice that human children's eyes may be dark but definitely turn vivid *ypio* as we age. It's probably an indicator of sexual maturity (he supposes), like the iridescent ypio trim on his own beautiful ladies (but we see them as only blank gray, btw). My [Tyndall blue](http://en.wikipedia.org/wiki/Tyndall_effect) iris is also a iridescence-based (not a pigment) color used by bird feathers, so the total effect involves colors used in body markings they are instinctively tuned to. Any earthly species will use roughly the same visible spectrum, so they overlap a lot even if not identical. Earthlings will never see our pupils as white, but as a tint that reflects (pun intended) the difference in our visions, on the short-wave end. IR-seeing animals would see all our body glow, not just the pupils. A richer FLIR sense might notice different emission coefficients on different materials, but I'll leave it to someone else to analyse that, or look at a FLIR instrument to see if there are useful distinctions. [Answer] White implies a high level of diffuse reflectance. Mundane pupils are dark because the light which passes into the eyeball through them gets absorbed, and no (or very little) light is passed back out through the pupils. So a being with uniformly white eyeballs would be blind (at least in the visible spectrum). Unless, of course, this is a *magical* being, in which case all bets are off. [Answer] The pupil is black not because it's coloured, but because there's no light coming back out to colour the image you see. A pupil any other colour than black implies light coming back out, which in turn implies that the eye is not working at full efficiency. Light coming out means that not all the light that has gone in has been processed, so there may be missing parts of the image the organism sees or the image may just be dim. It is, however, possible. The human eye has many layers or retinal receptor cells (the rods and cones that let you see light and colour). If an eye has just one or two layers, not every available millimetre of surface will be covered, so not every bit of light will be absorbed. This would seem to imply that the image seen would be incomplete, but since most of it would be there, the brain can fabricate the rest. You would probably find that this animal moves its head a lot more to make up for not having complete vision. This ensures it sees all that's going on, including its potential prey. ]
[Question] [ I'm Worldbuilding, and in my world, people can grow houses from seeds. My world is not a Fantasy one. Could this theoretically work, and if so, how? (Images by Finnian MacManus) [![house grown from trees?](https://i.stack.imgur.com/8eNAU.jpg)](https://i.stack.imgur.com/8eNAU.jpg) ![Probably interior of house](https://cdna.artstation.com/p/assets/images/images/014/708/256/small/finnian-macmanus-muvala-seed.jpg?1545119184) To start the growth of a structure, several plant weavers confer and attempt to guide powers into the architecture seed. (Not necessarily) [![organic growing structures? Picture brightened by me](https://i.stack.imgur.com/EXqPx.jpg)](https://i.stack.imgur.com/EXqPx.jpg) Depending on the seeds used, the structure will grow spires, large interior rooms, bedrooms etc. Is this possible to accomplish without magic? Edit: Mayonnaise2124, thanks for fixing my question! [Answer] **Yes... and No...** The [tree house or ship trope](https://tvtropes.org/pmwiki/pmwiki.php/Main/TreeVessel) has been found in science fiction and fantasy for a long time. Three famous examples are the [nature-magic-based Elves](https://www.pinterest.com/pin/323696291945754636/) of Tolkien's *Lord of the Rings,* the [Yggdrasil tree ship](https://www.pinterest.com/pin/328340629053315034/) from the *Hyperion* stories by Simmons, and the [big old tree house](https://www.pinterest.ca/pin/535646949410566493/) found in James Cameron's movie *Avatar.* Can you do it in real life? Li Jun makes a compelling argument. But a lot of this really depends on the size and application of the structure. * Size is your biggest problem. That first piece of art you show is a massive building. Without magic holding it up, such a structure could never be built on Earth. A single-story structure, sure. Maybe even a 2-story (20 feet or 6 meter) structure. *Maybe...* a 3-story structure (30 feet or 9 meters). But after that, I'd need to see proof that a strong enough wood could be shaped into such a structure in even a century's time. *And I'm going to ignore time... you have magic, after all. But obviously any serious structure on Earth would take a lifetime if not many generations to create. Hardwoods grow slowly.* * Complexity is your next problem. Theoretically you can weave floors and rooms into place... but every aspect of a tree continues to grow throughout its life, meaning those "rooms" are getting smaller day-by-day as the floors and walls get thicker through growth. I'm also having trouble with ensuring structural integrity of any sizable structure. Getting enough branches (or anything else) to grow in exactly the right place to create weight-bearing support beams and pillars... maybe a master gardener could do it — but again, I'd need to see proof of a multi-level structure. * Keeping such a structure sealed (from the rain, the cold, etc.) would be a neat trick. You can create walls and ceilings/roofs from the perspective of the Pacific Island peoples: woven fronds, etc., but I'm having trouble imagining solid walls, floors, ceilings, etc. * I'm going to completely ignore plumbing and electricity. Pipes and chases... I can't see that at all. * Stairs are a problem. Yes, you could form a series of horizontal-ish ladder-ish branch constructs that you could call "stairs," but keeping the wood flat for convenient stepping and then hoping it never grows beyond that shape... As with complexity in general, with the passage of time your stairs eventually require a hatchet to keep them usable. * And then there's the issue of what you intend to do with the building. Fireplaces? Metallurgy? Manufacturing? The more weight, heat, and vibration you add to the mix the less likely this can actually be done. (Remember, I'm thinking multi-story solutions, not simply a one-story solution where the Earth is the "floor.") So, not to rain too much on the parade, but while there's ample evidence suggesting the idea meets suspension-of-disbelief standards (as nearly 100 years of scifi/fantasy demonstrates), if you ask the question, "can it be done in real life?" the answer is "no, not to the expectations you set in your question." But don't let that stop you. It didn't stop Tolkien, Simmons, or Cameron! [Answer] ## Yes, it is Possible --- Here are some examples: [![enter image description here](https://i.stack.imgur.com/4ee8p.jpg)](https://i.stack.imgur.com/4ee8p.jpg) from: <https://en.wikipedia.org/wiki/Tree_shaping> [![enter image description here](https://i.stack.imgur.com/HOBlK.jpg)](https://i.stack.imgur.com/HOBlK.jpg) from: <https://www.permaculture.co.uk/articles/artful-science-tree-shaping> I will try to copy-paste some words here, maybe it can help, since I am not knowledgeable about it myself. ## Summary --- > > Tree shaping uses living trees and other woody plants as the medium to create structures > and art. There are a few different methods[2](https://i.stack.imgur.com/HOBlK.jpg) [...] such as pleaching, > bonsai, espalier, and topiary, [...] > Most artists use grafting to deliberately induce the inosculation of > living trunks, branches, and roots, into artistic designs or > functional structures. > > > ## Inosculation and Living Root Houses and Bridges --- > > Some species of trees exhibit a botanical phenomenon known as > inosculation (or self-grafting) [they] are called inosculate > trees.[3](https://i.stack.imgur.com/sNQJD.jpg) > > > The living root bridges of Cherrapunji, Laitkynsew, and Nongriat, in > the present-day Meghalaya state of northeast India are examples of > tree shaping. These suspension bridges are handmade from the aerial > roots of living banyan fig trees, such as the rubber tree.[4](https://i.stack.imgur.com/EbVce.jpg) The > pliable tree roots are gradually shaped to grow across a gap, weaving > in sticks, stones, and other inclusions, until they take root on the > other side.[4](https://i.stack.imgur.com/EbVce.jpg) This process can take up to fifteen years to > complete.[5] There are specimens spanning over 100 feet, some can hold > up to the weight of 50 people.[6][7] The useful lifespan of the > bridges, once complete, is thought to be 500–600 years. They are > naturally self-renewing and self-strengthening as the component roots > grow thicker.[7][8] > > > Living trees were used to create garden houses in the Middle East, a > practice which later spread to Europe. In Cobham, Kent there are > accounts of a three-story house that could hold 50 people.[9] > > > ## Pleaching > > Pleaching is a technique used in the very old horticultural practice > of hedge laying. Pleaching consists of first plashing living branches > and twigs and then weaving them together to promote their > inosculation. [...] useful > implementations include fences, lattices, roofs, and walls.[3][10] > Some of the outcomes of pleaching can be considered an early form of > what is known today as tree shaping. > > > > > In an early, > labor-intensive, practical use of pleaching in medieval Europe, trees > were installed in the ground in parallel hedgerow lines or quincunx > patterns, then shaped by trimming to form a flat-plane grid above > ground level. When the trees' branches in this grid met those of > neighboring trees, they were grafted together. Once the network of > joints were of substantial size, builders laid planks across the grid, > upon which they built huts to live in, thus keeping the human > settlement safe in times of annual flooding.[3](https://i.stack.imgur.com/sNQJD.jpg) Wooden dancing > platforms were also built and the living tree branch grid bore the > weight of the platform and dancers.[11] > In late medieval European gardens through the 18th century, pleached > allées, interwoven canopies of tree-lined garden avenues, were common. > > > ## Methods --- > > There are various methods of shaping a tree.[2][12] Some of > these processes are still experimental,[13]:154 whereas others are > still in the research stage.[14] These methods use a variety of > horticultural and arboricultural techniques to achieve an intended > design. Chairs, tables, living spaces and art may be shaped from > growing trees. [Some techniques used are unique to a particular > practice, whereas other techniques are common to all]. > > > > > These methods usually > start with an idea of the intended outcome. Some practitioners start > with detailed drawings[15]:7 or designs.[16] Other artists start with > what the tree already has.[17] :56–57 Each process has its own time > frame and a different level of involvement from the tree shaper. The > trees might then either remain growing, as with the living Pooktre > garden chair, or perhaps be harvested as a finished work, like John > Krubsack's chair. > > > **Aeroponics** > > In 1957, F. W. Went described "the process of growing > plants with air-suspended roots and applying a nutrient mist to the > root section", and in it he coined the word 'aeroponics' to describe > that process. In 2008, root researcher and craftsman Ezekiel Golan > described and secured a patent for a process which allows the roots of > some aeroponically grown woody plants to lengthen and thicken while > still remaining flexible. At lengths of perhaps 6 metres (20 ft) or > more, the soft roots can be formed into pre-determined shapes which > will continue thickening after the shapes are formed and as they > continue to grow.[12][21] Newer techniques and applications, such as > eco-architecture, may allow architects to design, grow, and form large > permanent structures, such as homes, by shaping aeroponically grown > plants and their roots.[14] > > > **Instant Tree Shaping** > > Instant tree shaping[12][22] starts with mature trees,[23] :53 perhaps > 6–12 ft. (2–3.6 m) long[13]:196 and 3-4in (7.6–10 cm) in trunk > diameter,[13]:172 which are bent and woven into the desired design > [23] :53 and held until cast.[24][25] Understanding a tree's fluid > dynamics is important to achieving the desired result.[2][17]:69 > > > > > Bending is sometimes used to achieve a design.[17] If a plant's tissue > is bent at too sharp an angle it may break, which can be mostly > avoided by un-localizing the bend. This is achieved by making small > bends along the curve of the tree. Bends are then held in place for > several years until their form is permanently cast.[17]:80 The tree's > rate of growth determines the time necessary to overcome its > resistance to the initial bending.[13]:178 The work of bending and > securing in this way might be accomplished in an hour or perhaps in an > afternoon depending on the design.[22] > > > > > Ring barking is sometimes employed to help balance a design by slowing > the growth of too-vigorous branches or stopping the growth of > inopportunely placed branches, using different degrees of ring > barking, from simple scoring to complete removal of a 3/8"-wide (1 cm) > band of bark.[17]:57, 69 > > > > > Creasing is folding trees such as willow and poplar over upon > themselves, creating a right angle. This method is more radical than > bending.[13]:80 > > > > > With this method it is possible to perform initial bending and > grafting on a project in an hour, as with Peace in Cherry by Richard > Reames,[13]:193[17]:56–57 removing supports in as little as a year and > following up with minimal pruning thereafter.[26] > > > **Gradual tree shaping** > > Gradual tree shaping starts with designing and > framing.[22][27][28][29] These are fundamental to the success of the > piece.[28][29] Once these are set up, young seedlings or > saplings[15]:4 3–12 in. (7.6–30.5 cm) long[28][29] are planted. > > > The training starts with young seedlings, saplings or the stems of > trees when they are very young,[15] :4 which are gradually shaped > while the tree is growing to form the desired shape.[9] There is a > small area just behind the growing tip that forms the final > shape.[27][30] The shaping zone,[27][30] it is the shaping of this > area requires day to day or weekly guiding of the new growth. The > growth is guided along predetermined design pathways;[23] this may be > a wooden jig [9] or complex wire design.[16] > > > With this method the time frame is longer than the other methods. A > chair design might take 8 to 10 years to reach maturity[23][31] Some > of Axel Erlandson trees's took as long as 40 years to assume their > finished shapes.[32] > > > > > Framing may be used for various purposes and might consist of any one > or a combination of several materials, such as timber, steel, hollowed > out trees,[6] complex wire designs,[16] wooden jigs,[9] or the tree > itself, living [13]:178 or dead.[33]:58 It can be used in many project > designs to support grafted joints until the grafts are > well-established. Some processes might employ framing to hold a shape > created by bending or fletching mature trees until the tissues have > overcome their resistance to the initial bending and grown enough > annual rings to cast the design permanently.[13] Others might use > framing to support and shape the growth of young saplings [23][30][34] > until they are strong enough to maintain an intended shape without > support.[30] Still other approaches might employ frames to guide the > roots of aeroponically grown trees into desired shapes. > > > **Grafting** > > Grafting is a commonly employed technique that exploits the natural > biological process of inosculation. A branch or plant is cut and a > piece of another plant is added and held in place. Various types of > grafting all share the goal of encouraging the tissues of one plant to > fuse with those of another. > > > Grafting is applied to create permanent connections and joints.[23] In > some cases, trees are grafted while they are growing, [35] while in > other cases, mature trees may be intertwined and the stems of two or > more trees are then grafted together to create chairs, ladders, and > other fanciful sculptures.[36] > > > **Pruning** > > Pruning can be used to balance a design by controlling and directing > growth into a desired shape.[30][33]:70 [34] Pruning above a leaf node > can steer plant growth in the direction of the natural placement of > that leaf bud.[13] Pruning may also be used to keep a design free of > unwanted branches and to reduce canopy size.[30][34] Pruning is > sometimes the only technique used to craft a project. > > > > > Trees repeatedly subjected to hard pruning may > experience stunted growth, and some trees may not survive this > treatment. > > > > > Using time as part of the construction is intrinsical to achieving > this art form. > > > ## Structure --- > > Living grown structures have a number of structural mechanical > advantages over those constructed of lumber[citation needed] and are > more resistant to decay. While there are some decay organisms that can > rot live wood from the outside, and though living trees can carry > decayed and decaying heartwood inside them; in general, living trees > decay from the inside out and dead wood decays from the outside > in.[38] Living wood tissue, particularly sapwood, wields a very potent > defense against decay from either direction, known as > compartmentalization. This protection applies to living trees only and > varies among species. > > > Growing structures is not as easy as it would seem.[39] Quick growing > willows have been used to grow building structures, they provide > support or protection.[39] A young group of German architects are in > the process of such a structure and they are continually monitored and > checked.[39] Once the trees are of age to be able to take on > load-bearing weight they are tested for stability and strength by a > structural engineer.[39] Once this is approved the supporting > framework is removed.[39] Projects are limited to the trees' weight > loading ability and growth.[39] This is being studied and the load > capacity will be proved by testing on prototypes.[40] > > > ## Images --- here several image for house [![enter image description here](https://i.stack.imgur.com/sNQJD.jpg)](https://i.stack.imgur.com/sNQJD.jpg) from: <http://facebook-tweet.blogspot.com/2011/04/fascinating-living-growing-architecture.html> [![enter image description here](https://i.stack.imgur.com/EbVce.jpg)](https://i.stack.imgur.com/EbVce.jpg) from: <https://imgur.com/gallery/ouAUx/comment/1299310169> ]
[Question] [ I had a rough idea of a species that has a tendency to blackmail other species into feeding it. The concept was a tree-dwelling species, a larger one that has few predators among the trees to worry about, that will harass a stronger land-based species into feeding it by threatening to help a predator find it otherwise. For now call this tree species a 'monkey' just to avoid pronoun confusion below, though I'm not committed to it looking or behaving exactly as a monkey. These 'monkeys' prey on at least one smaller land based predator that relies heavily on camouflage, for example a lynx or other smaller feline. Call this species a 'cat', though again it doesn't have to be feline in nature. When the 'cat' secures a kill the monkey will show up at a lower branch and effectively demand the cat offer it a small amount of meat from its kill. If the cat doesn't provide the monkey a bribe the monkey will follow it from above and make a constant call that a predator will be attracted to. Effectively the monkey will help larger land predators to find, stalk, and kill the cat unless/until the cat bribes the monkey to go away with food. In this scenario the monkey is a threat because it can follow the cat anywhere and the cat's camouflage doesn't work as well against a birds eye view as it does against land predators. Thus a species that usually survives by hiding from its predators now has something giving away its presence to those predators. The cat could potentially still get away from the monkey before a predator reaches it if it moves fast enough to out pace the monkey, but the cat usually has excess meat after a kill (it can't eat all of its prey at once) and is more likely to sacrifice some of that excess to the monkey then risk the monkey trying to get it killed. The monkey feels safe to draw this attention because nothing on the ground is a threat to it while it is in the trees, and it doesn't have larger tree-based predators it's afraid of drawing the attention of. I'm wondering if this could evolve and work on a partially instinctual level. That is to say none of these species is sapient or capable of advanced reasoning skills, though some of the behaviors could be taught by parents it should still be mostly habitual by now. Blackmail is simply an instinctual part of the monkeys means of collecting food, and the cat simply knows that if he doesn't feed the monkey something bad will happen when it shows up, without the monkey having to explain it's threat... I'm wondering if such a species could exist in the wild, and if so how it would evolve in the first place (there is a chicken and the egg problem with such complex behaviors becoming habitual, how do each of the three species, monkey, cat, and larger predator, evolve a habitual understand of what the monkey is doing well enough to play its part?) My current thought is that originally the monkey evolved a symbiotic relationship with the larger predator, to help it find and secure kills, in exchange for getting first dibs on the predator's 'left-overs'. Eventually the cats, having evolved a fear of monkeys due to their bringing predators to attack them, evolved the instinct to 'bribe' the monkey to shut it up. The monkey got his food at less cost then chasing the cat around waiting for a predator to kill it, and so accepts the bribe, and eventually food from bribes became their primary source rather then food after helping the predator secure a kill. Still, I'm not sure if this can be an evolutionary stable dynamic? [Answer] This actually sounds like something a monkey might do. Monkeys have been known to steal things and not give them back until bribed with food. All it takes is one innovative monkey, or a monkey that stumbles into this situation for it to become an established habit. Primates will teach each other, so if one monkey like species finds this to be an effective strategy then it will quickly spread. Primates can even learn the concept of money and target / steal money. The most likely scenario I can imagine is this "monkey" species as scavengers that stalk the "lynx" waiting to either gather in numbers high enough to steal the food or just wait until the lynx leaves. One clever or just lucky "monkey" realizes that if it makes enough noise the lynx will be driven off by a higher order predator, leaving the food. Noise => Food. The lynx would likely form sympathetic habits of either eating quickly, or allowing the "monkey" to steal some of the food to prevent the noise. **Further elucidation in response to comments**: This type of complex social relationship would require an amount of social cognizance not typical in most animals. This type of intelligence would likely be on the level of primates, corvids, elephants, dolphins, pigs, and border collies. [Answer] You're coming at it from the wrong direction. Everyone has to adapt. First, it's the predator which kills the lynx that has to adapt. This predator learns that the particular sound that the monkeys make means that there is a vulnerable lynx in that location with a fresh kill. Monkeys already instinctively call and have a a language for specific things. Once the predator learns that--the lynx will learn, likely accidently, that they better find a way to shut up the monkeys. One lynx or a few can learn this and pass it on to their offspring. This will be a learned behavior, not a matter of evolution. However, all the ones that don't learn it, are more likely die, so any stupid lynx that cannot, will be eliminated from the gene pool. So the behavior might not be instinctual or genetic, but the smarts to learn it WILL be. Now, the other problem is this: the higher order predator may just kill steal--that is, they may not bother with the lynx at all, and will just eat what they have killed once they are driven off. The monkeys may be smart enough to know that, so I would allow them a softer call at first--letting the lynx know they are there and want their take, but not so loud (yet) as to call the higher order predator. Also, if the kill isn't large, one monkey may not want to share with the others. You have the problem of, if one monkey is satisfied and there are like 50 in the trees, or even a dozen, even a large kill might not be enough. The higher order predator, meanwhile, has taught their offspring to listen for the call, even if it is faint, because it means food. One of two things will happen--either the higher-level predator will adapt to the new bribery system and still be able to find the lynx in this way (albeit a little later) OR the higher level predator will forget the meaning of the call at all. Meanwhile, the lynx may still be teaching their offspring this behavior, even though it doesn't have an advantage. Eventually, the behavior of the lynx, of giving the bribe, may actually fade away, unless the higher-order predator still uses the low call from the monkeys to hunt. Whether it is genetic or learned, if there's not advantage or edge to the bribery behavior for the lynx, eventually they might not engage in that behavior any more. You do want to look at the higher-order predator and THEIR response to this, because that informs how all the others will adapt. [Answer] So, I think this is a cool idea. To make it simpler, let's scale down the question a bit, because you're asking if it "can be an evolutionary stable dynamic." Let's have a plant and an ant. The ant colony hunts Red Mites, and as such, they gain a red pigment as well. This, unfortunately, has the effect of giving their position away. Through chance, the ants stash part of their Red Mite supplies in a pitcher-plant style plant. This plant, digesting the mites, also gains a red coloring. Ants learn that it's safe to congregate on the red plant, and the plants that are red are the plants that they store mites in, and if they can learn how to avoid being eaten themselves (or, at least, only lose acceptable casualties) they can become co-dependent. Now, this is way simpler than your question, but the solution comes out to be very similar: you could say the pitcher plant is "demanding a bribe" from the ants; because if the ants stop feeding it red mites, it's color is going to return to normal. The ants don't know what's going on; there's no intentional communication going on here. But, yes, this could end up being evolutionarliy stable. Perhaps the plant becomes more reddish by default, to allow the ants more leeway in it's bribes. Or maybe the best adaptation is to gain a blueish, or some other contrasting, color, which makes the ants even MORE visible to predators unless they keep the pitcher plant fed and, therefore, colored. **So we know it's viable. How about higher level creatures, like your monkey, cat, and tree?** So, let's actually make it a **monkey, squirrel, and tree**. The predator is the cat. Cats can access trees, and they prey on squirrels. These monkeys, being bigger and more adapted to trees, can easily evade the cats, while the squirrels, who must spend a lot of time on the ground and lower branches of the tree, are preyed upon. The squirrels are well known for collecting tons of food. They eat acorns which fall from this species of tree. They are well adapted to it, but the monkeys are not. They generally eat fruits from nearby trees. So how does the bribe work in? Well, say this acorn contains a small amount of THC, nicotine, or some other chemical that the monkeys enjoy. It has no effect on the squirrels (they process it just fine), but it makes monkeys happy. They, therefore, want to steal acorns from the squirrels. Not really being adapted to the land, they don't want to leave the trees. The acorns aren't really ripe and ready for the monkey until they've been on the ground for a few weeks. The squirrel, of course, doesn't want to give up it's acorns. So the monkeys, suffering from acorn withdrawl, start calling the cat. The cats learn that when the monkeys are behaving in a specific way, squirrels are nearby, and they start hunting the squirrels. Through natural selection or by accident, the squirrel ends up giving the monkeys some acorns, and amazingly enough, the monkeys chill out and stop making noise. The cats have optimized to hunt in areas where the monkeys are misbehaving, so keeping the monkeys happy is a good survival strategy for the squirrels. They collect acorns, select the best ones for the monkeys, and hand them off, turning off the monkeys, who leave them alone. This can become an even better deal for the squirrel, because the monkeys learn that protecting the squirrels also protects their source of acorns. So not only do they NOT misbehave and catch the cat's attentions, but they use their higher vantage point to scope out cats in the area, and either warn the squirrel, or scare off the cat (a few well placed pinecones should do it). **Yes, I just turned squirrels into drug dealers, and the monkeys into the mob.** But this ends up being the bribing situation you wanted. If the squirrels don't "pay up," the monkeys will assist the cat to hunt them; if the squirrels pay the protection money, the monkeys may actually assist the squirrel. The monkeys get the acorns they want and the squirrel gets to avoid being lunch. Sounds like a pretty good strategy for both. [![A completely unrelated comic.](https://i.stack.imgur.com/kVcRd.jpg)](https://i.stack.imgur.com/kVcRd.jpg) [Answer] Creatures with sufficient cognitive ability could develop this type of codependency through a variety of cause-effect mechanisms (mostly likely accidental and/or forced in the right direction by environment variables). As mentioned in other answers, primates can be "taught" the concept of money and bribe etc by environmental factors. For example, any setup that results in the "cat" seeing the causal relationship between *fully eating their food* (which is one way to make an "offering") and arrival of predators would eventually teach them (by natural selection, if nothing else). But let's say we are talking about species with zero or nominal intelligence (plants without brains and animals/insects working purely on instincts), which is also more interesting and "evolutionary". Here is one solution - 1. Let's say that we have the following setup - * **A carnivorous pitcher plant** (the ones that look like an open pitcher in which a prey would fall into) that blooms brightly colored/fragranced flowers to attract/trap other insects/animals *when the plant is hungry*. It's big and tall enough to allow an ecosystem of other animals. * **Bees** that are attracted to the flowers bloomed on the pitcher plant. * **Koalas** that eat those Bees and tend to be around wherever Bees usually congregate. * **Cats** similar to the Cat in your example living on the trees. Initially it doesn't know or care about the plant. * **Bears** that prey on of Koala. They would normally prefer to eat only Koala but could *opportunistically also eat the Cats if any are around*. So, to summarize - Plant creates flowers when hungry -> Bees eat flowers -> Koala eat Bees -> Bears eat Koala and Cat. Finally, let's consider a few mechanisms for the Cats to "offer" the food - * Some Cats are prone to accidentally dropping little pieces of their foods as they eat them and these pieces fall into the pitcher. * Or alternatively, the Cats catch bigger animals that they can eat at a time and tend to leave leftovers that drop into the pitchers. * Or, placing the kills in the pitchers result in the food to become pre-digested or better tasting or something; this means the Cats are actually rewarded for "offering" their kills for a few hours before retrieving it All would work but going with the first one one for this example. Now, in this setup, if the Cats don't drop any pieces of food in the pitcher, the plant blooms flowers which in turn attract Bees which in turn attract Koala which in turns attracts the Bear which also threatens the Cats. If the Cats drop pieces of food, the plant doesn't bloom and doesn't attract anything. Over a long period of time, natural selection will do its thing and only those groups of Cats will survive that instinctively drop pieces of their food (or, in other words, "offer some of their food"). With some environmental nudge, the actual expression of the behavior of "dropping pieces of the food" may evolve to look like an actual offering being made (as we humans understand the concept of offerings). Eventually even the Bears may learn to respond to the blooming and skip the intermediaries - Koalas and Birds. The cool part about this solution is that neither the plants nor cats is consciously aware of all this (at least initially), it's all driven by natural selection. We can have a lot of fun tweaking this solution, for example - 1. How to make the plant ask for a specific offering - we can say that the plant starts blooming when it "smells" the pheromones of a rabbit (because, let's say rabbit pheromones have a chemical structure similar to some enzyme or whatever prerequisite for blooming). It stops blooming if it gets to eat a rabbit. Now, seemingly amazingly, *evolution is going to teach the Cats to make offerings of rabbits whenever rabbits are around*. 2. How to make the plant to "call" predators in a more fantastical way - Let's say the predators (Bears) can't get to the Cats because Cats live very high up. Now we can claim that the when the plant doesn't get a specific protein (that can be obtained only from the offerings), its branches droop down (or result in aerial prop roots like that of a Banyan tree) making it climbable by the Bears. Now, it'd look to the outsiders that *when Cats stop making offerings, the tree creates a way for Bears to climb* The possibilities are endless... **UPDATE**: I realized that the question doesn't ask for a plant that forces an animal into offering food. Here is a solution for that version - Let's just add monkeys (zero intelligence animals unlike the ones in our world) to the plant in my previous setup and make the tree non-carnivore. Let's also say that if monkeys don't find better food, they start attacking the plant's unbloomed flowers which results in a mess that attracts a certain type of bees which eventually attract bears that threaten the cats. If the cats "offer" some of their food, the monkeys stay satiated and don't mess with the flowers. Its the same setup, the tree is still signaling the predator but now monkeys are interacting with the tree a certain way when they don't get food offered. The above process still works without any of the party to be too smart. I think I've a bunch of variations of this in my mind, I'll probably replace the whole previous "intelligent tree" answer with this one if I get time. [Answer] First the cats eat monkeys whenever they get the chance. The monkeys are smart and cautious and develop strategies like having their lookouts follow any cat around being loud. Cats try to avoid the monkeys and find sufficient other prey, but they still are bothered by losing days to monkey harassment. Eventually a cat does something which distracts the monkey following it. Say digging up a new monkey food source or scaring off something defending one. It still can't get at the monkeys because there are almost certainly other lookouts about, but it can now get on with hunting other stuff in peace. If the cat learns to do the distraction the behavior might be self reinforcing from both sides. The monkeys who associate the cat with the new food will follow and get food unavailable to the others, the cats with the distraction behavior don't get starved by monkey harassment. Even if the two species change to no longer have a predator-prey relationship at all the blackmail might last. Of course the monkeys gaining behavior to entice the cats to them would be expected to happen sooner or later and that really would break the blackmail down to a simple trade. [Answer] This seems like a very similar concept to the African drongo. (<https://en.m.wikipedia.org/wiki/Fork-tailed_drongo>) This little bird mimics the meerkat in order to steal food. It starts off by correctly alerting the meerkats to approaching predators. However its end game is to falsely alert them and then take its pick of the food which the meerkat has obtained. You could use a very similar thing where the two species have a more symbiotic relationship. Essentially your tree dwelling species evolves as a warning bell to help the land based animal. If it is not kept adequately fed it ceases to help. The land animal dies a grizzley death at the hands of some fearsome predator. This is not direct blackmail but it is a reasonable adaptation you could see happen. Tree dweller gets fed and so carrys on its genes. [Answer] One of the problems with blackmail is that it requires high level mental processes to process, both as blackmailer and victim. The other is that the victims sooner or later work out that "*if ever you pay the Dangeld, you will never be rid of the Dane*". It is an unstable social arrangement, not a stable one. War will replace payment. So I don't think this relationship can exist purely by evolution. It requires intelligence approaching the human level, at which point evolution has given way to society. There are quite a few cases where one species leads another species to prey, for mutual benefit. The bee-eater bird has a call that it only ever uses to communicate with people, who it leads to a bee nest. The people break it open to take the honey and the bird gets the leftovers. I can certainly imagine something like this bird co-evolving with the prey. Maybe in the future there will be bees that feed bee-eaters like aphids feed ants, so the bird doesn't need to call humans in to destroy the nest, and instead protects "its" bees against other bee-eaters and small predator species. But in hard times if the bees cannot keep the bird adequately fed, it will switch to calling humans. This would *look* like blackmail, but would be missing mental calculation by the bees and communication of an ultimatum by the bird. ]
[Question] [ Illnesses caused by bacteria can be held at bay by antibiotics, and some viruses can be fought with anti-viral medicine. However, I'd like to create a disease for use as a bioweapon that cannot be stopped. Here are some things I'd like the disease to do: * Be transferrable through fluids * Be harmful only to humans * Cause death within 48 hours * Be untreatable * Be able to discreetly enter the body - the terrorists that use it don't want to simply stab someone with a needle and inject in the bacteria/virus * Be highly contagious, to the point where mild contact between humans will spread it Is it possible to create a strain of bacteria or a virus that will create a disease that cannot be treated, cured, or even mildly inhibited by medicine? [Answer] **Basic Mechanism for Incurability: Biofilms** A significant problem in hospitals is how to combat bacteria the form [biofilms](https://en.wikipedia.org/wiki/Biofilm). These biofilms provide effective protection against a great many decontamination techniques both inside and outside the body. Let's build a disease around that mechanism. **Metabolic Characteristics** The pathogen's metabolic pathways closely resemble those of a normal human cell. **Detection Prevention** Since the host immune system uses [receptors on foreign bacteria](http://mizuhohsci.blogspot.com/2012/07/how-does-immune-system-recognize-and.html) to identify threats, our pathogen has considerable ability to mimic the host's receptor. (The pathogen mimics the extra-cellular receptors that the host uses to distinguish between self and not-self.) Since the immune system recognizes the pathogen as "friendly", it is not attacked. Theoretically, it would only take a very small amount of the pathogen to induce death in the host. **Spread within Host** Form plaques/[biofilms](https://en.wikipedia.org/wiki/Biofilm) in capillary blood vessels that chock off blood supply to periphery areas. Once blocked off, the bacteria goes into anaerobic mode and starts pumping out a nasty toxin similar to [botulinum toxin](https://en.wikipedia.org/wiki/Botulinum_toxin) and more plaque to coat the infected area. The toxin kills off the surrounding tissue then uses the dead tissue as raw material for building a plaque wall. Hiding behind the plaque prevents clean up by the immune system or the lymphatic system. Bacteria that haven't lodged anywhere continue to reproduce as quickly as they can. As plaques build up in major arteries and veins, the body will start to experience overall decreased functionality. In some/many cases, plaques that form in the heart will duplicate symptoms of [Atherosclerosis](http://www.emedicinehealth.com/hardening_of_the_arteries/article_em.htm), though a thousand times faster. **Symptoms** * Difficulty breathing * Irregular heartbeat * Black pustules in the extremities. * Loss of cognitive ability * Severe organ pain * Black phlegm in coughing * Extreme fatigue * Severe itching around pustules * Irritation to the lung lining causing severe coughing **Spread between Hosts** Given the pathogen's ability to create strong biofilms in all environments, they may be able to last for long periods outside a host. Strong coughing by the victim will spread the pathogen through the air and depositing it on all manner of surfaces. Once the pathogen lands, it forms a biofilm sufficient to preclude destruction by bleach or any other strong chemical sanitizers. This ability makes sterilization incredibly difficult and allows the bacteria to popup again at a later time to reinfect a host. Being airborne dramatically increases the pathogen's ability to spread itself. A good cough or two by an infected person in a large, busy international airport such as JFK, Paris, Tokyo, or Heathrow would spread the pathogen across the globe in short order. Also, under certain atmospheric conditions the pathogen will form into spores and pop off the colony to float around and infect someone else. Consider how hard it is to contain a mildew or mold invasion. That's exactly how hard it is to clean up this pathogen. **Defeated Decontamination Mechanisms** *Targeted viral infections* - Won't work because you'd kill the host along with the pathogen. *Heat* - In the food safety business, it's well known that you can't kill the spores that become bacteria. So even though a food may be sterilized after cooking at food safe temps, if the food is then left at room temperature then it will rapidly become contaminated again. Getting heat high enough to kill the spores usually means making the host into charcoal too. *UV* - Biofilms take the brunt of this kind of ionizing damage. UV filters don't work against bacteria encased in UV blocking material. *Chemicals* - Hospitals currently fight biofilms that evade such strong oxidizers as bleach. This pathogen has a similar biofilm capability. **Impossible to stop** By mimicking a host's receptors it forms a very difficult to hit target for the immune system. Any drugs that boost immune system function will not help here. By mimicking a host's metabolic pathways, any drug that targets them will also target the same pathways in the host, leading to death. [Answer] Green gave me an idea, and I'm adapting this from a [pretty good book](https://en.wikipedia.org/wiki/The_Girl_with_All_the_Gifts) I read recently... Instead of bacteria or virus, I propose a fungus. Specifically, [Ophiocordyceps unilateralis](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis), engineered to work on humans instead of ants. Unlike the book, the fungus would work similar to how it works on ants, and not turn people in to zombies. Once infected, Ophiocordyceps takes over the hosts brain, giving them an overwhelming compulsion to climb to the highest point they can find, then sit down and die. The fungus would then sprout, releasing spores to infect more people. The fungus takes over it's victims by mimicking their own bodies chemistry, so it's impossible to block. Wind would distribute the spores over great distances, and then be breathed in, or could grow through the skin like it does with ants. The spores can stay dormant for a long time, waiting for a host to come along, and it wouldn't work on animals because of differing brain chemistry. If someone had walked through a cloud of spores, their skin would be covered with them, and so skin to skin transmission would be possible. Likewise, some spores would be shaken loose, attaching to other surfaces. [Answer] One type of infectious disease that is completely incurable is prions. The word prion comes from the words protein and infection. Proteins are large molecules composed of strings of smaller amino acid molecules. These strings of amino acids fold into specific configurations that then perform a role in the cell. A prion is a protein that has misfolded for some reason and has taken on a new form. What makes the prion a disease is that this new form is capable of causing other proteins of the same type to also misfold and take on this new configuration. Thus the prion is essentially able to reproduce itself by converting the normal, properly-folded, and functioning protein into the prion form. This can cause a number of problems for the infected host. First, the protein is misfolded and therefore no longer performing the action it is responsible for in the cell, and second the prion form gradually builds up and accumulates into plaques. Prions are responsible for many diseases in humans and other animals and are collectively known as transmissable spongiform encephalopathies. This is because all known prion diseases kill their hosts quite slowly. They mostly affect the brain where the prion builds up over months or years and results in the death of the neural tissue. This doesn't necessarily have to be the case though. A prion capable of converting normal proteins into more prions more efficiently could theoretically spread through the body incredibly rapidly and cause sudden death. Prion diseases are entirely untreatable. Hypothetically a vaccine of some sort could be devised, but there are no extant treatments. All it would take to be infected would be the inhalation or ingestion of a single prion molecule. The infectivity would be very high if the prion protein was found in blood or mucus or other bodily fluids, both because the prion would begin to replicate immediately upon contact and because any coughing sneezing or hemorrhaging would release it. Potentially it could even replicate outside a host body. Prions are also extremely hard to kill. To render them ineffective you have to denature the protein, getting it to unfold from its infectious form. This requires both extreme heat and some potent chemicals making proper sterilization incredibly hard. Even a long run through an autoclave is considered insufficient. A prion could still be infectious long after its host died. The cooked meat of an animal that had eaten a prion infected corpse could be infectious even if the prion doesn't effect that creature. The prion would be species specific if the infectious protein were sufficiently divergent from its homologs in other animals. [Answer] # Old solutions aren't fun It was already discussed in the question > > [Is non-manmade pandemic a realistic threat to modern first world?](https://worldbuilding.stackexchange.com/questions/19945/is-non-manmade-pandemic-a-realistic-threat-to-modern-first-world?lq=1) > > > that bacteria are quite limited due to antibiotics. They could be made resistant, but that kind of a pain to organise, and maybe stronger antibiotics could be developed to counter. Viruses are somewhat limited, as once one of more people managed to survive it, a vaccine can be made. Recently there was news of a vaccine for Ebola being tested. HIV was one of the worst due to its propensity to metamorphose. But even that one seems to be receding against new treatments. All that make it frustrating for your wanabe terrorists. Plus, the trend of viruses to be either very infectious OR very lethal makes it kind of hard. # Bio-nanobots No, probably, if you allow a bit of time for the science to evolve... [Nano-robots](https://en.wikipedia.org/wiki/Nanorobotics) is already an emerging technology. For example, [some](http://phys.org/news/2014-08-cancer-hunting-nano-robots-tumours.html) will be aiming to kill cancer cells. Giving it a bit more time, bio-technologies, should allow to build your nano-robots from biologic materials. And you "program" them to aim at destroying vital organs: like liver. Much like computer viruses, your robots should try to convert the internal body parts to reproduce themselves. They should be designed to circulate in body fluids. If the reproduction rate is well adjusted, you could have an easily infectious disease. Depending on the tuning of your robots, you can limit to certain organs, in order to limit the spread to other animals. There is of course, the limit of treatment. Once they have been identified, some means will be deployed to fight them. Probably inhibitors, or defensive nano-robots. But again, experience in computer viruses tell you that the best is to try to simulate an evolution. That the robots appear to change, while keeping the same functions. You take the risk of an evolution which could spread to other animals, but you gain a safety against counter measures. [Answer] A disease like this appears in the last two books of the *Time Riders* series by Alex Scarrow, although I forget its name. Despite killing its host in mere minutes (by liquifying the flesh) it doesn't self limit because as soon as it reaches a host it begins releasing spores (I think this would make it a fungus). It also continues to use resources from the host long after they are dead. The horrifying way in which it kills it victims causes widespread panic, so qauruntines are largely inneffective. Because it is so infectious and kills so quickly, it is not safe to seek (and there is no time for) treatment, and researching or developing a cure becomes impossible. [Answer] You need the disease to take time, maybe make it kill in a week so it has time before it gets noticed. And the symptoms shouldn't be noticeable. You need something that can be linked to different diseases, or the government will make a vaccine sooner. And you shouldn't do through fluids it should be airborne. ]
[Question] [ The bicyclops are half man half bicycle - a bit like a centaur. EDIT \*\*\* Note that someone suggests the title be changed to "Half person half bicycle". However, in my story, the females have a different nomenclature and do not have bicycle wheels. I think "man" is perhaps clearer \*\*\* They do not have legs because the lower part of their body is mostly bicycle. How can I arrange for the pedals to be turned using mammalian musculature or alternatively, if there are no pedals, how can musculature rotate the wheels? **Note** The bicycleness is due to there being wheels (made of bone), the front wheel is steerable. Joints/axles are lined with cartilage that is renewable because the 'frame' is flesh and blood. So effectively the wheels, when fully developed, shed any living tissue and become exposed bone. The juvenile forms have the wheel-bones encased in flesh. They locomote by a different method. On maturing, the wheel-flesh falls away leaving dead bone. The supporting structure (or frame) remains living. Note, the body shape isn't too important provided that the bone wheels can rotate and steer. [Answer] # Piston [![enter image description here](https://i.stack.imgur.com/ZLmBP.gif)](https://i.stack.imgur.com/ZLmBP.gif) We will take for granted that the wheels are separate from the rest of the body. The problem is arranging musculature to turn the wheels without getting wound around some axle or other. To that end what you need is a piston to turn either the pedals or to turn the wheels directly. The piston has one part that goes in and out. This is easy to achieve. The only rotating part of the contraption is the wheel itself. No tangled ligaments required. Like a real bike, the back wheel is powered and does not steer. The front wheel is unpowered and does the steering. Just put it at the end of a "spine" so it can bend both directions symmetrically. Wheels being dead bone will wear down. I suggest the biclops grows a smaller wheel fruit in front of the dead one. The wheel fruit does not touch the ground. Eventually the old wheel crumbles, the fruit detaches from the body and becomes the new wheel. The piston arm also grows longer to reach. **Added Later:** Like always, it seems nature perfected the design thousands of years ago: [![enter image description here](https://i.stack.imgur.com/g4t6a.jpg)](https://i.stack.imgur.com/g4t6a.jpg) The tricycle has exactly four moving parts. The three wheels are separate from the frame. The fork that holds the front wheel is separate to allow steering. The pedals are attached to the front wheel. The child's legs work as pistons. Notice the child's ligaments and tendons remain safely inside its body and not wrapped around any other part of the contraption. The body of the trike is rigid. It is no stretch to imagine the frame being attached to the child. I suggest (a) replace the back two wheels with one wheel, (b) move the pedals to the back wheel and (c) connect the fork to the frame with a moving joint. Now you have back-wheel drive and only two moving parts. [Answer] ## Gut-like symbiosis As Slarty observes, the situation you're trying to create will be hard to reach through evolution (though not impossible). A solution to both problems would be for the anatomically modern bicyclops to be a semi-symbiotic relationship with a separate, wheel-shaped creature. Imagine that long ago there used to be a wheel-shaped creature that evolved on its own, and a separate cyclops creature with some kind of pistoning limb (h/t Daron) for crude locomotion. I imagine this might have happened in the water. The wheel-shaped creature was a big fan of some of the waste produced by the cyclops. Over time, the cyclops learned they could exploit wheels, who would tolerate the exploitation because it came with a regular supply of that delicious cyclops waste. Every cyclops would seek out a wheel, like hermit crabs seek out abandoned shells. Eventually, the wheels' own reproductive cycle became integrated with that of the cyclops. How far-fetched is this? Well, stuff kind of like it has occurred in real life. Consider the human gut, which is a "micro-biome" inhabited by a whole bunch of weird bacteria, which you need in order to digest the food you eat. Those bacteria *aren't human*: mother passes them to child during childbirth. They don't come from your DNA, but your body makes special accommodations for them, and depends on them as a vital part of its daily activity. Since they aren't part of the human genome, and are kind of a hand-me-down, there must have been a time in the distant past when these bacteria did not live in our bodies and our bodies didn't have a special chamber designed for them. At a smaller scale, I think the story with mitochondria is kind of similar: mitochondria didn't used to be part of a cell, but at some point they essentially joined forces and now all animal cells have them. Organic life is a beautiful and horrific intertwining of things. So, too, with the bicyclops: Half man Half bicycle All cy**c**l**op**s [Answer] Circular muscle fiber. This is a regular muscle fiber: [![a regular muscle filament that makes up a muscle fiber:](https://i.stack.imgur.com/rDTKV.jpg)](https://i.stack.imgur.com/rDTKV.jpg) You see it consists out of myosin (blue bristling thing) and tropomyosin (the twisting thing). The Myosin’s bristles grab hold of the Tropomyosin and pull itself along to contract, using the opposing myosin connected to it to stay in place. Now imagine we cut this in half and only take the left part of the fiber. The myosin would pull itself into the tropomyosin until it reaches the Z-disk barbed end. So you remove the Z-disk and barbed end, then lengthen the tropomyosin while making a large circle the size of the bicycle wheel. The myosin is now able to pull itself along through this in an endless circle. Now you lengthen the myosin to fill up the entire tropomyosin length, and connect it to the bicycle wheel. Now your giant single muscle fiber can pull on the wheel and make it turn. Put many of these in increasingly large circles and you can pull the wheel along. Bloodflow happens at the axle, where a cartilage and bloodvessle surface bridges the gap between the moving wheel and the place where its attached to the body. An extensive lymph system pumps the blood around and pushes it back out once its done. The nervous system would need a circular dendrite to continuously have contact with the nerves of the body, or it would have a few grey matter cells like in the spinal column deal with remembering and managing the wheel part with only once every X centimeters on the wheel a nervous connection to send data along quickly. Although the muscles themselves can be connected to the nervous system on the body side. This would basically look like a fleshy sleeve around the wheel, with only the “tire” part sticking out. [Answer] Luckily for you, this already exists: the [handcycle](https://www.getcycling.org.uk/handcycles/)! [![Man riding a racing handcycle](https://i.stack.imgur.com/wyIKG.jpg)](https://i.stack.imgur.com/wyIKG.jpg) Developed usually for people who can't use their lower limbs for propulsion, handcycles have an arm-powered crank to drive power to the wheels, usually the front wheel (as these are mostly trikes). Some handcycles are steered like a regular bicycle by turning the wheel about the fork, and others by leaning into the turn (which may be more natural for beings born into this configuration, and reduces your joints by one). As your byclops have a normal human torso, they can use their arms to operate the crank, just like human athletes with spinal injuries. In fact, I imagine the crank and gear system to be mechanical, an engineered improvement to their natural somewhat inefficient propulsion, which may be more wheelchair-like. Some byclops will prefer an aerodynamic, forward-leaning stance with low-lying cranks and performance-oriented gears. Others will prefer an upright, leisurely position with a longer chain and lower gearing. [Answer] ### The EYES Have It **Introduction** The bicyclops is a symbiotic creature, descended from a disc shaped creature that made use of incredibly common magnetic minerals to repel predatory creatures; and another, multilimbed creature that evolved to make use of the same magnetic minerals in its mating behaviours. The common occurrence of the proto-disc creatures in the vicinity of the proto-bicyclops creature put the two in regular contact. Over the course of evolutionary history, the discoids became encompassed within the bicyclops, the latter coming to control the former's reproduction via pheromone mediation, allowing the discs to reproduce as a part of the composite creature. **Physiology** The best way to understand the mechanism by which the bicyclops locotmotes is to examine the structure of the ocular lens of the terrestrial animal. Essentially, the lens is a roughly circular, almost wheel like, structure suspended in the anterior portion of the eye. It comprises multiple layers, notably an outer layer of epithelial cells, a middle layer of nucleated fibre cells and a central nucleus of clear fibre cells that lack organelles. As the lens matures, epithelial cells migrate towards the centre, becoming fibre cells and adding new layers to the lens. [![enter image description here](https://i.stack.imgur.com/cdOvg.png)](https://i.stack.imgur.com/cdOvg.png) With that image in mind, the bicyclopian bio-wheel design is similar. Rather than a transparent lenticular nucleus, these creatures have layers of fibre cells that contain particles of magnetic mineral, arranged in such a way that they are capable of interacting with magnetic objects outside of themselves. Of note, while the human lens is perhaps 0.75cm, the bicyclopian bio-wheel can be up to a metre in diameter! **Mechanics** The capsular fluid acts as a buffer, as lubricant for the gyre, and as the medium in which nutrients and wastes are transported and also into which partially differentiated fibre cells migrate until they attach to the gyre for growth or repair. Within the symbiotic portion of the bio-wheel, a similar capsule like arrangement is to be found, but rather than ciliary action causing the gyre to spin, in this case, fluid pumps act against ridges along the bony rim. Thus the central portion of the symbiote remains relatively stable whilst the rim and external tyre rotate around it, activated by the host's magnetic gyre. The external appearance of the tyre is of an extremely tough bony plate surmounted by a somewhat spongy and fibrous hoof-like plate which is used to dig into the earth and provides locomotive traction. Manouvres such as turning, leaping and so forth are accomplished primarily by spinal flexion and by weight shifting. Of note, distant ancestral creatures once had six independently mobile limbs. Modern bicyclopes retain independent mobility only in their forelimbs. The left and right medial and posterior limbs have become fused masses of bone, looking much like a wishbone's bifurcation. **Interface** [Answer] The bicyclops as described, may actually be very difficult to evolve naturally because by definition it is not a single entity. It consists of multiple parts by definition. The frame could become morphed into the bone of a body, but the wheels are separate entities by virtue of their need to rotate. There are no macroscopic wheels or similar structures in the living world. I suspect that the problem is the multitude of required intermediates would all prove to be less "fit" than the original. It might be possible to use some form of artificial selection to generate a wheeled being. The process might involve growing a biological wheel structure linked to the body by some sort of tube structure (preventing rotation but allowing growth and nutrient flow) followed later by the tube breaking away like an umbilical cord. However supplying nutrients to the wheel across the axial would still be problematic. Especially if the wheel contained any flesh that needed blood supply, oxygen and nutrients. The musculature required to pedal would be easy, but the link between a rotating pedal "bone" and the wheel would also be a problem as above. [Answer] Super cool idea! I love it. I can think of three propulsion systems based on hydrodynamics: * The byclops blow air towards the back and newton's third law makes them move forward. Fart-jokes aside, take a look at this: <https://www.youtube.com/watch?v=DYl2UWYRpug> * The byclops blow air on the wheel to rotate them: <https://www.youtube.com/watch?v=wPxFVBc_EVw> * The byclops blow air inside the wheel through the axel and the air is expelled at the level of the 'tire' in such a way that the wheel rotates. The wheel would rotate like a sprinkler: <https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR4rdVucM-NZtmzw5PpGPaaTWGx1TMDxV1wIJi8-n9Qfw&s> The byclops could use a combination of these three mechanism depending on the circumstances. For example, the first method would be best to get started, but would only enable the byclops to go as fast as the expelled air. The other two methods could then be used to maintain speed or speed up. Moreover, they could have some kind of mucus (or water) pouch to mix in the expelled air. Or maybe, the inside of the wheels shed some bone particles. This would raise the air's density and enable them to go faster without increasing the actual air flow. Of course, I have no idea if this would work in reality. It could be that hydrodynamic propulsion is jut not efficient enough and completely impractical in this case. But, is sounds cool to me. [Answer] # Like a waveboard The wheels wiggle relative to each other to generate motion. If the wheels are angled out of parallel, then moving them in and out sideways (from the point of view of the bicyclops) will generate forward or reverse motion. Each wheel follows a sinusoidal path in anti-phase. See <https://en.wikipedia.org/wiki/Caster_board> for more detail on waveboards. [Answer] As others have pointed out, a fully rotating wheel would be a separate component, so the best I can think is multiple wheels, not all of which are in contact with the ground at one time. They twist and rotate like a joint, but then lift and spin backwards to avoid any ligaments/cartilage getting tangled. Leg-wheels of sorts. Not very akin to a bicycle. If you do want to persevere with the idea of an organic self-replenishing wheel that is able to fully rotate though, I'd have thought a design based off a unicycle would be more intuitive. [Answer] I'm not sure if I am allowed to mention it here, but I typed descriptions of the creature in various AI apps. The following creations appeared. None of them exactly matched what I was hoping for. I wonder if anyone knows how to make these things work. [![enter image description here](https://i.stack.imgur.com/0lns3.jpg)](https://i.stack.imgur.com/0lns3.jpg) ]
[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. In the red corner, a top of the line **Main Battle Tank**, you can have your pick, but let's say a tricked out [M-1A2](http://en.wikipedia.org/wiki/M1_Abrams#Variants_and_upgrades) 'Abrams' with a full [Nuclear-Bio-Chem Protection](http://en.wikipedia.org/wiki/CBRN_defense) kit. In the blue corner, a **[Nuclear](http://de.wikipedia.org/wiki/Kernwaffenexplosion) [Device](https://www.youtube.com/watch?v=UTdy1Yp1h5A)**. Let's start by assuming a standard Teller-Ulam design, say a [W70 warhead](http://en.wikipedia.org/wiki/W70) set for about 15kt TNT equivalent yield, similar to the Hiroshima bomb. As an initial set up, set the detonation point 50 meters above ground at about 500 meters from the tank. The tank is on, sealed, and facing towards the blast. There is a clear line of sight. **Would the crew survive? If not, what would be the minimum distance to give the tank crew some sort of fighting chance? If yes, how much closer can the detonation take place? Alternatively, could some modification be made to the tank to dramatically increase survivability against atomics?** *Note: As the hard-science tag is meant to indicate, feel free to persuade me with numbers, if so inclined. Numbers are sexy, especially when it comes to nuclear attacks and radii of total and utter destruction! In part inspired by [this story](http://io9.com/the-atomic-tank-survived-a-nuclear-test-then-went-to-w-1542451635).* [Answer] # The Assumptions That "Abrams" tank is 50m below and 500m as measured on the ground. Pythagoras (at least [his theorem](http://www.wolframalpha.com/input/?t=crmtb01&f=ob&i=sqrt%5B50%5E2%20%2B%20500%5E2%5D)) says that's about 502m away, so that is the number I am going to use as "the distance" from the nuclear explosion. This is considered a "surface burst" when surveying literature about nuclear explosions. There is a clear line of sight. This is (somewhat) important to establish, because atmospheric conditions affect different aspects of the blast. John Walker was nice enough to make an interactive version of the United States Department of Defense's and Energy Research and Development Administration's 600-odd page [report on nuclear weapons.](https://www.fourmilab.ch/etexts/www/effects/) Despite the date of the report (1977!), the science appears to be good, and I will be using this as a source to inform this answer.$^{1}$ # The Energy the Tank Receives A nuclear explosion appears to have two main destructive methods of "doing damage" to things around it. There are the mechanical shockwaves of the explosion and then the thermal radiation from it. It is estimated (from section 7.01) that around 70-80% of the energy released$^{2}$ from a nuclear weapon is thermal, and the remaining 20-30% is kinetic energy in the form of the blast wave. I'll be using the values of 75% thermal energy and 25% mechanical energy. # Thermal Energy Several sections in chapter 7 deal with the energy delivered by a blast to targets at varying distances. Sections 7.07, 7.96, and 7.101 build upon each other and eventually yield an equation for the amount of thermal radiation received by a unit of area ($Q\_{thermal}$) at a particular distance D is: $$Q\_{thermal} = \frac{\tau E\_{thermal}}{4 \pi D^2}$$ Using this equation and the table for section 7.101, $\tau = .18$. Tau represents the absorption of the atmosphere due to water and the density of air molecules at the surface. Adding a [quick conversion factor](http://en.wikipedia.org/wiki/TNT_equivalent) for the explosion's thermal energy, [we](http://www.wolframalpha.com/input/?i=.18+*+.75*15+kiloton+of+TNT+%2F+%284*pi*+%28502+m%29%5E2%29) find that $Q\_{thermal} = 2.675 \frac{J}{mm^2}$ (or $2.675 \*10^6 \frac{J}{m^2}$) # Kinetic Energy This comes in the form of the "blast wave" which the tank will need to cope with. The energy does not hit all at once; indeed, the blast wave hits and then the pressure gradually decreases until it becomes negative. At which point, the atmosphere rushes back in, and restores the pressure. The peak pressure and dynamic pressure discussed in chapter 3 are important values to consider for such a blast. Section 3.19 claims that most damage is caused by the blast wave hitting a target, and not be the subsequent phases of the blast wave. Although a tank designer would be concerned about this, I am going to simplify this a little and ignore the subsequent phases. As this is a surface equation, we can take the advice from 3.34, and treat it as an air burst with double the energy. This **is not** always the case, and it is an oversimplification, but we would need much more information to determine exactly how much energy (and pressure) gets at the tank. We are going to use a similar equation for the distribution of energy per unit area as the equation we used for thermal energy. We are going to remove tau and double the kinetic energy though, so the equation is: $$Q\_{shock} = \frac{E\_{kinetic}}{2 \pi D^2}$$ [We](http://www.wolframalpha.com/input/?i=.25*15%20kiloton%20of%20TNT%20%2F%20%282*pi*%20%28502%20m%29%5E2%29) calculate that to be about $9.909 \frac{J}{mm^2}$! That's more than three times more mechanical energy per unit area than thermal energy per unit area. This blast wave looks promising for a lot of destruction. If we take the [Kingerly-Bulmash equation](http://www.un.org/disarmament/un-saferguard/kingery-bulmash/) to estimate the overpressure, we come to an overpressure of ~258.6 kPa. That is enough to "[severely damage](http://en.wikipedia.org/wiki/Overpressure)" cement buildings four times over. # The Ability of the Tank to Cope This is a little difficult, because it is in the best interest of many tanks, *tanks used to defend living solders on active duty*, to not publish their material properties. Specifically, I looked for and failed to find properties of [Chobham Armor](http://en.wikipedia.org/wiki/Chobham_armour#Heavy_metal_modules), a type of depleted uranium armor.$^3$ What I do know is this; heavy armor variants involves a depleted uranium layer along with one, but likely more, layers of composite material. So I do not become the focus of investigation of national entities (the rep here isn't worth it), I'm going to look at something I can find information about; [uranium](http://en.wikipedia.org/wiki/Uranium). With a bulk modulus of 100GPa, it can get very thin before it deforms due to the shockwave of our nuclear blast. Due to the fact that our tank isn't a box, and it has angles to it instead of flat walls, even the reflective pressure, which can spike up rapidly, may not be enough to deform the tank. Additionally, uranium is good at conducting heat, so our tank needs insulation from other sources to protect its occupants. Finally, uranium is good at absorbing the some deadly types of radiation, so it can offer protection there for the crew. It should be noted that weaponized nuclear explosions generally do not cause items to become radioactive. As a matter of fact, you can visit [ground zero at Nagasaki](http://en.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki#Hibakusha) without radiation suits! The metal of the tanks should protect the inhabitants from most cancer-inducing radiation. The blast wave itself would most certainly push the tank. Weighing in at about [69.54 tons](http://www.globalsecurity.org/military/systems/ground/m1-specs.htm), this isn't trivial. If I do a gross oversimplification and model the tank as a box with a 93 in high and 144 in wide, it has an area of around $8, 639, 982 mm^2$ (this is an overestimate). That's around 85 613 588 J of energy. Assuming this is all kinetic energy, and using $K=\frac{p^2}{2m}$ (solving for p), the tank gains 52 m/s in speed from the blast wave. Obviously, the tank's grip on the ground will determine how far it goes. We'll use the kinetic friction coefficient found [here](http://cedb.asce.org/cgi/WWWdisplay.cgi?43816); .57. Through a series of calculations, I find the distance travelled by the tank is about 46 cm, over 9.3 terrifying seconds. This is because the tank is so massive and has such a good grip on the ground. (Once again, I should say that the 46 cm is from the initial blast, not the total *blast wave,* which may push it a little further.) It seems the tank, under these conditions, will likely survive, but the occupants will not. All said, it appears that a nuke-proof tank needs a lot more to protect the inhabitants than a uranium shell. Something like [Object 279](http://en.wikipedia.org/wiki/Object_279) may do. I could not find or calculate exact details on the needed properties, though, but it is a place to start. # The Occupant Survival The occupants in this blast need to worry about that shockwave and the heat. A proper nuke-proof tank needs to absorb the shockwave and the radiation. It must also do this before those things get to the crew. You need a lot of stiff and soft material between you and a shockwave to prevent the shockwave from hurting you. Looking at [bomb suits](http://en.wikipedia.org/wiki/Bomb_suit), you need foams and some other materials to protect you from the blast wave. The exact configurations of these things are beyond my expertise and the length we would like to see on SE sites.$^4$ I therefore will just say this: these foams could also help insulate you from the thermal energy of the blast. If you play with the Kingerly-Bulmash equation, you will notice that a human can survive the blast wave from about 3km away. Obviously, a tank can get closer, but I do not know how much the tank wall impedes mechanical waves. Therefore, I know that the tank can be closer, but I cannot confidently say by how much. At 3km away, you need to worry more about the radiation than the shock wave. Not knowing how much an Abrams tank absorbs radiation, I can only say that the tank will likely be a good spot (with its high-density armor) to avoid irradiation. Uranium is used, after all, in [shielding radiography cameras](http://en.wikipedia.org/wiki/Depleted_uranium#Shielding_in_industrial_radiography_cameras). As uranium absorbs [gamma and x-rays well](http://rationalwiki.org/wiki/Depleted_uranium), it will greatly help deter the negative effects of radiation in a nuclear blast. It is supposedly [five times better](http://en.wikipedia.org/wiki/Uranium-238#Radiation_shielding) at absorbing radiation (x-rays and gamma rays) than lead! In fact, some people are trying to figure out how to use [depleted uranium in concrete](http://web.ornl.gov/%7Ewebworks/cppr/y2001/rpt/114398.pdf) to contain nuclear waste. --- **Footnotes** 1. This report, despite being dry and official, even has the occasional funny heading such as that in chapter 6: *Underwater Shock: Bikini Experience* 2. This does not include the energy emitted from the atmosphere. As the radiation goes out from the device, it is partially absorbed and then re-released by air. This is due to the air becoming ionized or excited, and then falling down to its rest state. 3. This is bad news for this question, but the publication of this information is worse news for the world in general. 4. I may come back to this to provide a better answer. [Answer] I am an instructor in the U.S. Army (active Guard) and was a tanker on M60A3's and M1A1's from 1982 through 2006 when I became a Paladin mechanic It HAS been done, with a much less survivable "Centurion" British tank. The blast moved the tank a whole 5 feet. It was damaged and the sensors placed inside showed that the crew would have most likely been killed from the pressure wave. The M1A1 is much more survivable. Another thing to note, the instantaneous radiation of the detonation is LESS lethal than the blast and heat, unless it is the legendary... NEUTRON BOMB! Then, the radiation is lethal to a distance greater the blast/heat. The site I used for my source is below. <http://io9.gizmodo.com/the-atomic-tank-survived-a-nuclear-test-then-went-to-w-1542451635> [Answer] Operating a M1A2 there are ICBM and Nuclear Protections from pressurizing the inside, sealing all hatches and hull to blowing out the inside of the tanks air of radiation. [Answer] They would likely not survive. Even IF they had some magical lead shielding which would protect them from some forms of radiation coming from the blast they still would die because their lead armor wouldn't protect them neutron radiation. The only way they could survive FOR AWHILE is to have some kind of layered shield protection of multiple substances. Something that could at first deflect the non neutron radiation like the lead then some other material to absorb the gamma radiation from neutron absorption which would occur and finally some more lead to protect from the gamma radiation. FYI, This tank would be incredibly heavy. As PipperChip told you even once you protect your crew and tank from radiation you now need to protect them from the blastwave. All in all this is not cost effective for the protection of less than 5 men. [Answer] They are pretty durable vehicles. Withstanding massive explosive forces at point blank range. But the question is what aspect of the blast are you talking about? The EMP from the blast. The air detonation wave? Ironically the Abrams M1A2 uses depleted uranium in it's armor matrix. Depleted uranium is used as a radiation shield so it may survive the blast, the emp and the ensuing fall out. Tanks have already survived nuclear blasts, an M4 sherman was modified with lead coating for the Trinity test. [![enter image description here](https://i.stack.imgur.com/SYG2X.jpg)](https://i.stack.imgur.com/SYG2X.jpg) ]
[Question] [ Inspired by this question: [What would it take for society reach a point where the time it takes to learn leaves no time to discover?](https://worldbuilding.stackexchange.com/q/5294/2871) We live in a world where no one person or group of people truly understands all of our technology. The majority of people involved in technology today are specialists and only have an understanding of a narrow portion of their field of study. For example, there are millions of people that can program in a high level language, but don't really understand how that code actually is being interpreted by the hardware (and don't really care). Will there ever be a time where we can no longer train enough people that have a deep understanding in technology to the point where certain forms of technology are lost? Is it possible that we have already reached this point and are already beginning to decline? [Answer] > > Will there ever be a time where we can no longer train enough people that have a deep understanding in technology to the point where certain forms of technology are lost? > > > Sure, that has already happened. Various languages, damascus steel, certain stained glass techniques, how to move giant blocks to build pyramids... Was that caused by specialization? Debatable. Disinterest in an old/niche technology helps drive things. A desire to protect valuable trade secrets can drive things. And depending on your view, things like Beethoven or Mozart or Shakespeare's skill/mastery has already been lost due to a lack of comparable peer to pass down the expertise. These are only slightly more famous examples of swordmaking or glassmaking skill that is slightly more common. And another thing to consider is the difference between knowledge and understanding. Historians can know about things, but it's one thing to study something and another thing to [master it](http://en.wikipedia.org/wiki/Outliers_%28book%29) through frequent use. [Answer] The key part of your question is the word 'we'. We, that's all of humanity. Look at human knowledge, of science for instance, in this way: ![http://www.wired.com/2009/03/mapofscience/](https://i.stack.imgur.com/nzyh3.png) [Source](http://www.wired.com/2009/03/mapofscience/). Our knowledge is all interconnected. Early on, individuals were working with a much smaller map, they were near the core. The work they did was growing our knowledge in significant, but relatively small ways. Today there is work happening all over the map. People are advancing the boundaries of human knowledge on all fronts. Specialization allows individuals to abstract the lower level things, like your example of assembly, and make progress in the high levels. Raising the base level for the next scientist to stand on. As Newton is often quoted as saying > > If I have seen further it is by standing on the shoulders of giants > > > So, for your question, will *we* not be able to maintain our level of progress? As individuals things may slow down, but we add more and more individuals to the pursuit everyday. As a species, collectively, we will only keep advancing and accelerating our understanding of the universe. The universe is full of incredibly complex problems for us to solve and each solution unwraps a whole set of new complex problems. If we ever stop because we think we've learned everything, it will likely be due to hubris rather than fact. [Answer] Personally, I believe the hyper-specialization of the modern world is sometimes overstated. Telling ourselves that architects don't know anything about building, or programmers don't know about hardware, is a way for relatively ordinary people to flatter ourselves, because it suggests we could be architects or coders if we'd chosen that as our major in college. But I've noticed that often, the really brilliant people in a given field aren't constrained by their supposed specialty. John Carmack writes amazing software because he is very much into low-level hardware; architects like Calatrava or the Smithsons make buildings that could only come from a deep understanding of engineering or construction (respectively). Although a much larger proportion of the population now works in intellectual fields, I'd suggest that the number of people truly advancing human knowledge is as small as ever, and if you look at that minority, they're just as erudite as Newton and Liebniz were. It's true that only a very few people (and places) have the wherewithal to manufacture a CPU or perform a heart transplant tomorrow, and that may be a weakness in our global civilization. However, if there were some catastrophe, I think we'd find that there are people scattered throughout the world who have the knowledge and intellectual agility to reinvent those skills and techniques fairly quickly. [Answer] Its fair too say that as someone specialise's in one thing, they have less time to spend gaining knowledge in other things. This means discovery's that require knowledge of two fields at once are less likely to be found by that person - especially if it leaves a high level of detail in both. This does not mean humans as a species will stop developing, however. We have developed tools for communication, and structures for the exchange of knowledge. Its not unreasonable to assume we can use this to get past any "inter-discipline limits" on progress. For example; As long as facts are entered into databases in a readable format, and published in an way accessible to others, then its possible for computer programs to spot patterns that humans are unlikely too. A computer program could see correlations along the lines of "sunspots effect crops" only for things humans are infinitely less likely too see connections in. As correlation isnt necessarily causation, this would only give you a short list of potential things to investigate, which scientists could then study to see if its real. But it completely sidesteps the need for specialists in two fields to spot said connection. [Answer] Not necessarily, though it is possible. As you say, most people are specialised. But given how just how specialised many people are, this begs the question how we make our current technology. For example, look at supercomputers (or even normal computers). Look at vehicle production. These processes aren't done with just one person operating everything, nor with one **discipline** of people. Computer manufacture involves people who understand processor architecture, OS designers, materials specialists, screen makers, precision robotics, and of course, engineers to make sure all the machines work. Car manufacture is similar: although it is mainly robotised today, the robots need maintenance, and someone has to design the car in the first place. None of these people can do all the jobs in the factory. So, the point is, for complicated jobs you get a group of people together and they do the job by working with each other. In the future, we may well have far more complex technology. I think that as this happens, the teams we will need to work the processes and machines will grow, and the fields they each study will narrow. So, in theory there definitely is a limit: where there are not enough people to fill all the required roles. However, it is entirely possible that among our new technology there will be advanced AI and computer memory. We may end up being able to build robots and upload all the necessary information for them to do many jobs for us. This would end up with everyone being employed in robotics manufacturing, until we build robots to do that at least. So yes, there is definitely a point where this will happen. However, if our technology advances at the right rate then we may be able to save it by building helpers. ]