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[Question] [ That is to say, could a planet be big enough to have other planets orbiting around, while not orbiting around any star? [Cha 110913](https://en.wikipedia.org/wiki/Cha_110913-773444) seems to be close to what I'm looking for, but its classification is still a bit vague. And if yes, would life be possible, on any planet of that system? I know life is possible in lightless environments, but I wonder if the various variables here would change this. And pushing the stretch even further, could human life be possible there? Not necessarily originating from there, but maybe as a colony. [Answer] I'll first address [Cha 110913-773444](https://en.wikipedia.org/wiki/Cha_110913-773444) specifically. Checking the Wikipedia page yields some interesting information: * Mass: 5-15 Jupiter masses. This means that it is likely a planet - extremely low-mass brown dwarfs are typically in the mid-20s, in terms of Jupiter masses * Spectral type: [L-dwarf](https://en.wikipedia.org/wiki/Brown_dwarf#Spectral_class_L). This is consistent with it being a brown dwarf, as many brown dwarfs are of spectral class L or "lower" (i.e. colder). The gist of this is that it doesn't give off a lot of light. * Luminosity: 0.000096 solar luminosities. This is really, really dim, dimmer than many (possibly most) brown dwarfs. That sounds like a planet. * Temperature: 1,350 K. This is really low for a brown dwarf, although it may still be one. I'm not sure if that's surface temperature or estimated core temperature. In the latter case, it could be a sign of a massive gas giant. My completely-non-expert assessment is that it's a planet. But you can disregard that, if you want. [Some experts](http://www.nasa.gov/vision/universe/starsgalaxies/spitzerf-20051129.html) are saying it's a brown dwarf, so you may want to just agree with them. However, some are on the fence: > > There are two camps when it comes to defining planets versus brown dwarfs," said Dr. Giovanni Fazio, co-author of the new paper from the Harvard-Smithsonian Center for Astrophysics. "Some go by size and others go by how the object formed. For instance, this new object would be called a planet based on its size, but a brown dwarf based on how it formed. The question then becomes what do we call any little bodies that might be born from this disk - planets or moons?" > > > Either way, it doesn't seem too conducive for life. [Pre-planet-forming materials](https://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20051020.html) have been found around other brown dwarfs, though. As the first article said, > > Astronomers have become more confident in recent years that brown dwarfs share another trait in common with stars - planets. The evidence is in the planet-forming disks. Such disks are well-documented around stars, but only recently have they been located in increasing numbers around brown dwarfs. So far, Spitzer has found dozens of disk-sporting brown dwarfs, five of which show the initial stages of the planet-building process. The dust in these five disks is beginning to stick together into what may be the "seeds" of planets. > > > The second article states, > > Apai and his team used Spitzer to collect detailed information on the minerals that make up the dust disks of six young brown dwarfs located 520 light-years away, in the Chamaeleon constellation. The six objects range in mass from about 40 to 70 times that of Jupiter, and they are roughly 1 to 3 million years old. > > > The astronomers discovered that five of the six disks contain dust particles that have crystallized and are sticking together in what may be the early phases of planet assembling. They found relatively large grains and many small crystals of a mineral called olivine. > > > --- The issue is, this thing is small, and its disk may not be massive enough to form planets. If Cha 110913-773444 is a planet, it may not have captured a lot of matter in its disk, because it may have been chucked out of its home system. This means that large bodies may not have formed. If it's a brown dwarf, then it may have accreted more matter. Still, the disk may not be massive enough to form large bodies. The other issue is the luminosity of the object. Life generally needs solar energy (although tidal forces can produce geothermal heat on a body's satellite) to grow and spread. If this is a planet, it will have a low luminosity, and thus life won't have it easy. If it's a brown dwarf, it will give off more energy, but still not a lot. In summary, I think it's unlikely life will form. The disk may not be massive enough to form planet-sized (or moon-sized) bodies, and there may not be enough energy for life. --- Optimistic Note I recently asked [this question](https://worldbuilding.stackexchange.com/questions/12311/how-can-a-type-ii-civilization-influence-accretion-rates-from-a-debris-disk-to-a), and it made me realize that it's very possible for this object to accrete matter from a passing star with a debris disk. If someone answers that question, I'll be able to tell you just how much, but I can assume that, given a close enough passing distance and a high enough density, the brown dwarf can accrete a decent amount of matter. It's doubtful as to whether it could capture enough to form a protoplanetary disk (because it's so low-mass), but it's possible [Answer] Habitability of a planet orbiting a brown dwarf or other very low luminosity body would presumably be dependent on geothermal energy. Plenty of ink has been spilled on the possibility of Europa (a moon of Jupiter) hosting life. It's well out of the habitable zone for Sol, and doesn't get much energy from Jupiter either, so these theories depend on geothermal energy. Colonization of such a geothermally-driven planet might be possible, but it would either have to draw resources from a more earthlike world, depend on future-magic (replicators), or (more interestingly) have a radically weird (possibly designed/terraformed) ecosystem that derives energy from geothermal vents rather than solar radiation. You could probably even tell a just-so story that leads to humanlike life evolving on such a world, but it would stretch the limits of suspension of disbelief if they were TOO humanlike (for example, having eyes that detect 430-770 THz.) One thing to keep in mind is that widespread natural availability of geothermal energy would more or less be dependent on very high levels of volcanic activity. It would be a chaotic world for sure, and intelligent life would likely be forced to remain nomadic even well beyond our level of technical advancement. (Stray too far from volcanic activity/geothermal vents, there's nothing to eat and you'll freeze, stay too close and you'll get crispy fried.) [Answer] Adding to what HDE said. Anything is possible, but originating life on any of the moons/planets around such a planet is unlikely. However, that doesn't preclude the ability for things to survive on the 'moons' surrounding it. I would guess the moons would likely be bodies it picked up along the way, so an earth sized planet would be unlikely, though Ganymede is slightly larger than Mercury so you never know. I just think it would be less likely for it to pick up a large body as it is floating through the cosmos. If there is enough of an energy source, say a solar array that can capture large amount of the planets radiation or if there is enough gravitational forces or a molten core to tap for energy or even large amounts of fissionable material, then yes humans could live there. I would consider it mostly to be either an outpost as a way point for travelers/traders, a science station or refugees that want to be left alone to pick such a lonely and difficult place to live. [Answer] There are proposals that true rogue planets (i.e. an Earth sized(?) planet ejected into deep space) could retain life, either under ice (a Steppenwolf planet: <http://arxiv.org/abs/1102.1108>) or under a high-pressure hydrogen atmosphere (<http://www.nature.com/nature/journal/v400/n6739/abs/400032a0.html>). Certainly a planet like one of these could be orbiting a sub-brown dwarf (under 13 times the mass of Jupiter) which would meet your criteria. It is also possible that a large moon could be heated by tidal forces if it orbits close to the rogue planet. [Answer] Let me list these other two very interesting objects along with Cha 110913: [WISE 0855−0714](http://en.wikipedia.org/wiki/WISE_0855%E2%88%920714) * This is the most interesting one because the estimated temperature (derived from luminosity, distance - only 8 ly and mass) is in the 225-260 K (-40 to -13 C) degrees, that is, [extremely cold](http://www.nasa.gov/jpl/wise/spitzer-coldest-brown-dwarf-20140425/#.VH8VqzHF-So) for a sub-brown-dwarf * It masses 3-10 Mj, a lot less than the currently accepted 13Mj needed to be able to fuse deuterium. * It does not orbit any other star, thus it can be considered a rogue planet [PSO J318.5-22](http://en.wikipedia.org/wiki/PSO_J318.5-22) This is very interesting as well, because even if it hotter and bigger than WISE 0855−0714 (> 1000 K and ~ 6.5 Mj), it is thought to be just 12 million years old. ]
[Question] [ So last year I started writing a post-apocalyptic story, and then realized I had no idea what the world was really like, and quite a few things just didn't seem to make sense. One of the biggest that jumped out at me was the abundance of running automobiles tooling around in my story. Which got me thinking: Could such a thing really happen? To set the stage, the short version is that in the near future Earth was the target in a cosmic shooting gallery of cataclysmic proportions: While no single blast even matched, say, the [Tunguska event](http://en.wikipedia.org/wiki/Tunguska_event), there were so many across a period of many days (weeks, even) that virtually the entire surface of the planet was devastated, and every major city (and many minor ones) was pulverized into oblivion. (What no one in this world (yet) realizes, though, is that this was a targeted attack intended to wipe out civilization, but not necessarily exterminate the planet.) Cue the inevitable collapse of every recognizable society, and fast forward a few years to the scrappy survivors of the human race having banded together into communities of virtually every description scattered across the ruined wasteland of their planet. Now, certainly, any vehicle that survived this apocalypse, and could handle the terrain of this new world, would be usable for a certain period of time afterward, certainly at least until it ran out of fuel. And no doubt there would be opportunity to scavenge some fuel here and there, but with essentially no more oil rigs, let alone refineries or the infrastructure to distribute these products, certainly fuel wouldn't last long, would it? And of course there's the myriad of other fluids that have to be periodically topped off or even replaced. Maintenance would be another difficulty -- spare parts might be easier to come across, and for much longer, but eventually you'd break down somewhere without access to what you need. So really, I suppose the question is: Given the utter destruction of modern society, how long could one expect motorized vehicles to continue to be usable by the survivors? [Answer] *updated tl;dr: fuel is* a problem, so is wear - alternative fuel sources will be required, as will some serious mechanical skills to patch the cars - for a 1st world country that has mostly newer cars, expect most to break down within 2 years, with very few left after 4-6. Calculations below.** Some variables I dug up to help calculations: all numbers are approximate and correspond to values taken for years 2009-2013 as far as I know. Also, using scientific notation to prevent zero overload. Rounding is performed on an arbitrary basis. also fuel units are in gallons and barrels because that's the units they're reported in online - I would much prefer metric since I don't live in a country that uses imperial units, but gotta bite the bullet this time. ## Worldwide numbers usage and production: * Total number of automobiles: `1e9`-`1.2e9`[[1](http://en.wikipedia.org/wiki/Motor_vehicle)] * Total number of automobiles produced per year: `80e6`-`90e6`[[2](http://en.wikipedia.org/wiki/List_of_countries_by_motor_vehicle_production)] * Total number of barrels of gasoline produced per year: `8.03e9`[[3](http://www.indexmundi.com/energy.aspx?product=gasoline&graph=production)] Now we need to check distribution of these across people and cars. I'm electing to use US numbers here since they're more readily available and the US seems to have both lots of cars and consume lots of gasoline, so if the numbers work out for the US, they should work in an apocalypse - if not, we can adjust them downwards to see how far we'd have to go until it's workable. ## US numbers usage: * Total number of automobiles: `250e6`[[1](http://en.wikipedia.org/wiki/Motor_vehicle)] * Automobiles per capita: `800 per 1000`[[4](http://en.wikipedia.org/wiki/List_of_countries_by_vehicles_per_capita)] * Total gasoline usage in barrels per year: `3.2e9`[[5](http://www.eia.gov/tools/faqs/faq.cfm?id=23&t=10)] + per day: `8.77e6`[[5](http://www.eia.gov/tools/faqs/faq.cfm?id=23&t=10)] + per automobile per day: `0.03508` production: * Total number of automobiles per year: `11e6`[[2](http://en.wikipedia.org/wiki/List_of_countries_by_motor_vehicle_production)] + per day: `31e3` * Total number of barrels of gasoline per year: `3.4e6`[[6](http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=pet&s=mgfrpus1&f=a)] + per day: `9.6e3` Now, I know nothing about average compatibility of parts between automobiles. It might be high or low, or anything in between, so I'm not going to include it now. There are obviously other factors that influence maintenance and usage: battery lifetime and wear, makeshift solutions, alternatives used, dangers and vast numbers of cars destroyed. I'm going to assume none of these factors play a role for now. What I am going to assume is that the world goes to hell pretty quickly - in a matter of days. Lets be generous and say that despite the bombardment, we get 2 days worth of production done before production stops abruptly. Lets also assume, all cars in the world have half their tank full and assume that this means they have about 8 gallons in there[[7](https://answers.yahoo.com/question/index?qid=20071220211509AAQnuJe)]. Since major cities are completely obliterated, we have to find out what percentage of people and cars are left. Lets say 20% of people and cars are outside city centers[[8](https://people.hofstra.edu/geotrans/eng/ch6en/conc6en/distancedensity_sample.html)][[9](http://www.fhwa.dot.gov/planning/census_issues/archives/metropolitan_planning/cps2k.cfm)]. Of that 20%, we'll assume 5% survives the bombardment, since most of the surface is destroyed. That leaves: * Automobiles: `1.25e6` * Survivors: `3.6e6` * Gasoline barrels left in cars total (42 gallons per): `240e3` * Gasoline barrels produced but unused before apocalypse: `19.2e3` + total: `260e3` > > edit - I originally had calculated that fuel availability would last > an outrageous 20 thousand years, which is horribly wrong. Brian > Drummond in the comments caught the error and with the proper > calculations (aka, calculating for all cars not just one) it turns > out that with the amount of cars left and the daily consumption of > fuel for a city car today (which is about 10 miles per day), there's > about 6 days of fuel left (again, lol). > > > This scarcity is further compounded by my original estimate of how far > cars would travel daily, which I placed in the range of 60-125 miles, > since the daily consumption was equal to about 10 miles, which is too > low for a post-apocalyptic world (you want to save fuel so you either > don't use a car or use it to travel long distances). If we assume > about 100 miles average use whenever you move a car, we're left with > about about 15 hours of continuous driving (this assumes the tank has > enough fuel for ~150 miles plus its share of fuel from what has been > produce in 2 days within the country[[7](https://answers.yahoo.com/question/index?qid=20071220211509AAQnuJe)]). That means, if > every one of those cars where to travel on the first day, trying to > escape or find safety, they'd be out within the day. There'd be no > usable fuel left, not even in refineries, gas stations etc. - so the > calculations about how long it would take for cars to break down must > assume an alternative source of fuel, which of course, if not ideal > for the car's engine, will cause it to fail sooner. Cut the amount of > cars to a fourth per year! Unless you have statistics on how many > older cars exist - if there's lots of them, you might have more cars > left. See vsz's comment for more details. > > > Also, as the numbers stand, we have 3.8 (lets say 4) people per car > which leaves no room to say "yeah but what if less cars are used?". > Even if less cars where used, we're obviously in the range of days > rather than hours - not a big improvement. If you add the weight of > equipment and provisions to the estimate, it's even more bleak. > > > If you want to see the original text, just see the edit history > > > Now how long can we expect a car to work until it breaks down? Lets assume cars last for `100e3` miles on average (half of what they're expected to if maintenance is available[[11](http://en.wikipedia.org/wiki/Car_longevity)]) and they're already half-way there, so about `50e3` miles left on each car on average. Based on the average daily consumption of gasoline and the average fuel efficiency[[7](https://answers.yahoo.com/question/index?qid=20071220211509AAQnuJe)] we get about `10` miles per day which is very low, so lets assume a highest bound of `125` miles per day. That gives us about `400` days average life for each car, a bit over a year. If the average usage is half that much, we get `800` days, which is a bit over 2 years. Obviously, people skilled with car maintenance, with available parts or scrap to turn into parts and a bit of creativity will get them working for longer, but I doubt you'll get cars older than 5-6 years still in working condition. Of course, that's speculation. So I'd say, as a rule of thumb, halve the amount of working cars every 2 years after the apocalypse. After a decade, you're left with about `40e3` cars in the US, most of them hosts to parts of their fallen brethren. In 20 years, you have about a thousand cars left. This further removes fuel as an issue - it will never run out by car usage alone, but the cars will run out pretty soon. [Answer] Something I haven't seen mentioned yet is that modern gasoline blends actually have a pretty short shelf life. Unless your post-apocalyptic survivors have taken special precautions, most of their gasoline reserves will be unusable in just a few months. I would expect this to be a problem long before any of the other parts start wearing out. Older-model, bio-diesel-powered vehicles seem a lot more plausible though. References: * <http://www.fuel-testers.com/expiration_of_ethanol_gas.html> * <http://theepicenter.com/tow021799.html> or just google "shelf life of gasoline" [Answer] In addition to batteries and fuel, I'd worry about tires. The unerring [interwebs](http://m.cartalk.com/content/do-tires-expire) talk about six years as the manufacturers' recommended shelf life; most would probably still be acceptable for several more years, in a post-apocalyptic setting, but prone to sudden blowouts. Handy when you need a plot device! The slow decay of tires is affected by low-atmosphere ozone levels, which should drop quickly if industrial civilization stops. However, asteroid impacts would damage the high-altitude [ozone layer](http://physicsworld.com/cws/article/news/2010/oct/11/asteroid-crash-would-devastate-ozone-layer) (), increasing UV levels at the surface, and therefore accelerating the [decay of tires](http://www.rvdoctor.com/2009/10/uv-damage-to-tires.html?m=1) in the open. Scavenging tires from cars on the side of the road will therefore probably be futile after a few years, but tires in buildings, especially if wrapped or otherwise protected from air, may be good for much longer. Very valuable! You may want to ask another question, "can one improvise car tires?" FWIW, Mythbusters did OK with solid wood. [Answer] I believe that early tractor engines were designed to run on vegetable oil because that is what would be available to farmers out in the far reaches. They could be self sufficient for their fuel. We still have bio-diesel engines and you still hear about the conversions to use McDonalds used frying oil. So would automobiles be around, certainly plausible. Would they run on gasoline? Not real likely, though if humanity is wiped out in large swaths then it could take a long time to use up what can be found in station tanks. Decent roads to drive them one could be a bigger problem [Answer] Going through this very same topic. Blended petrol have a lifespan of about 3 months. diesels maybe 6 months. There is one company doing stabilisers and refreshers but you need to keep adding them every 3 months or so. Fuel left stood turns into shellac, even in sealed containers. Its fine for heating but not running an engine on. Vegetable oil might by an option, it needs lye and methanol, which aren't tricky to make. A drawback might be the shelf life of vegetable oil, I'd have to check on that. Fuel ins't an issue, there are plenty of Compressed Natural Gas vehicles about. As long as the containers are fine and don't corrode it doesn't really have a shelf life. There is plenty of natural gas around so its easy to obtain, and a biodigester, like Mad Max Beyond Thunderdome is feasible. Growing a biodiesel crop isn't really an option, it takes a lot of acreage to make fuel, and you need to be growing food. Batteries are an issue, modern rechargeable are ok for maybe 5 years. Lithium watch batteries are the best at 15 years, but so small. Old lead acid batteries are probably the most viable solution; they can be rebuilt. Solar panels generally have a viable lifespan of 10-15 years, their yield degrades rapidly. Wind turbines need a lot of maintenance, due to being so exposed to the elements. Steam, from gas, coal, biomass boilers, is a much better option. Plenty of small steam turbines in factories and they can run a few megawatts, Also worth looking at diesel electric trains, they use a diesel engine to drive a turbine to generate electric for the wheel motors. Tyres are the clincher. Current recommended life span for tires is 6 years, from date of manufacture, that's stamped on the tyre. They oxidise so maybe vacuum packed, but I would think no more than double that. I'm looking into urethane and synthetic tyres, but a lot use petroleum products and its how much crude oil is left, and can you refine it. [Answer] There have been quite a few settings that revolved around this concept. Some...much better than others. The first that comes to mind is [Road Warrior](http://en.wikipedia.org/wiki/Mad_Max_2), ah, Mel Gibson before he was totally crazy. I think you have a couple options or rather a time range of options. For the first few months to years (depending on depopulation levels, more depopulation the longer the gas lasts) you should be fine with cars being fairly common. The second phase would be a gradual reduction in the number of cars to the point where you hit Stage 3. Essentially there are no running vehicles left, and to add a little flavor I would just like to say that I have seen a 4 door sedan being pulled by a pair of donkey's before...that pretty much describes stage three. So if the inclusion of vehicles is important to you, have it happen sooner after the cataclysm, less cars, have it further down the road...metaphorically speaking. [Answer] One option for fuel that doid not come up yet is [wood gas](https://en.wikipedia.org/wiki/Wood_gas). This has been done in France and Germany during WWII, when fuel was not given to cilivialns easily: BAsicall you build a sort of oven that burns wood with not enough air for complete combustion, the resultin gas is combustible and can drive your motor. Wood gas vehicles need frequent fuel stops (wood is far less energy-dense per weight or volume than gas), mor maintenance and have less power but it can be done. Look around the internet for pictures and tips on how to convert cars so you know how your cars will look like. One starting point couild be [here](http://www.lowtechmagazine.com/2010/01/wood-gas-cars.html). [Answer] While other answers have pointed out various limits that are realistic I thought I'd point out there's a "loophole" if you will for each of them. * The autos would have part wear for sure but regular disassembly and cleaning plus lubrication can drag it out for a very long time. Driving cars at slower speeds reduces wear and resource consumption tons. * Oil can have an indefinite shelf life. * Gasoline can last 25+ years in a metal can with some stabilizers. (if you can find gasoline you can probably find additives). * If there's enough meteors to wipe out each major city then your looking at a huge drop in population so there are extra cars lying around everywhere for spare parts. As far as massive usage of cars in the midst of the attack... Let's be honest if there's meteors filling the sky is your first thought going to be "To the bat-mobile!"? No, its going to be "To the bomb shelter!". * Diesel engines can run on vegetable oil with minor modifications. As far as I'm aware you could generate electricity and grow corn to produce corn oil pretty easily. * Batteries even if continuously recharged and unused lose a certain percent of life. However you could convert back to a hand crank design pretty easily. * The tires point is a good one but they also provide the solution: wood (thanks for that). So to summarize if you had a decent enough repair man and a source of electricity to make oil (abandoned plant, wood powered steam engine, hand cranked alternator) you could keep a car running for a pretty long time in such a scenario and if you got a hold of certain parts probably pretty close to indefinitely. (I'm thinking zero wear plastics, ceramics, or super-alloys like you might find in racing or experimental parts but used at <40 mph on a regular car). It however would definitely be hard as you would need to find the solution to each issue rather quickly to prevent the issues from being "insurmountable". If nobody paid attention to the issues it would be pretty easy, as others noted in their answers, to run all the viable autos into the ground. [Answer] Ok, first of all gasoline has a short shelf life. In just a few months it will go bad. Even if you use fuel stabilizer and keep it in an air tight tank it will go bad after two years. There is also avgas, but avgas only has a shelf life of a year in ideal conditions. Diesel has a shelf life of a year as well. To me, the car that would work the best is an electric car but recharging a car in an apocalyptic world would be hard to do. Or you could look at some of the older cars that run on propane. It has an indefinite shelf life depending on the shape of the tank, propane does not go bad if it remains sealed. ]
[Question] [ I have this idea for a world where the creatures, though they look organic externally, are actually mechanical in nature and when damaged reveal their mechanical innards, with pipes pumping coolant instead of veins pumping blood, the damage usually damaging the pipes and making them 'bleed' their coolant, and some sort of energy acquisition system as part of their bodies that necessitates the coolant being pumped. They can reproduce by means of a small factory in 'female' units receiving slightly randomized transmitted blueprints of themselves from 'male' units that are compared with the female's blueprint and interlaced with the male's blueprints to allow evolution, and grow by means of structural/system stages that activate over time and extends limbs, decompacts/bulks-up the frame, dedicates more power to the limbs because their algorithm is obviously efficient in resource acquisition to have survived this long and make the 'adults' stronger than the 'young', etc, and eventually die on their own by means of the mechanical structures breaking down over time. Due to these creatures being mechanical in nature, they can have abilities that are unlikely, if not impossible, for organic creatures to have, and is the primary reason for why the human-like machines in this world need to be rather clever in fighting things that can make electricity arc like a [Tesla coil](https://en.wikipedia.org/wiki/Tesla_coil) or can lift boulders and fling them like it's nothing. The female units can 'eat' mineral compounds and other resources, which is what they use as the resources for their factories. The only organic lifeforms on this world are plants, who introduce energy to the 'ecosystem' by their usual means of growth and photosynthesis. I already have 'herbivores' that eat the naturally growing plants and burn them in a furnace stomach and converts the heat energy to stored electrical energy via water that has been previously taken in being heated up and turning to steam to run turbines where a creature's lungs would be and vent any excess steam by 'breathing out' if they took in too much water earlier. As was discussed in comments: I am open to different herbivores performing different forms of resource processing and energy acquisition, like condensing plant matter into fuel and using combustion engines to make energy. My problem comes with making predators in this world. Since they can't get energy from plants like the herbivores, how would they go about extracting the energy from the herbivores after killing/overpowering them? [Answer] > > converts the heat energy to stored electrical energy > > > The predators steal the electricity. [![car steals electricity](https://i.stack.imgur.com/ocV4o.jpg)](https://i.stack.imgur.com/ocV4o.jpg) <https://www.ubergizmo.com/2013/12/nissan-leaf-owner-arrested-for-stealing-five-cents-worth-of-electricity/> Some predators would remove the "battery" or whatever the apparatus is by which lower trophic level creatures store electricity. Some predators tap into their prey and drain the battery but leave the organism intact. Of course there are trophic levels - perhaps the lowest level carnivores are mostly parasites on the herbivores that drain them but do not kill. Higher trophic level creatures might concentrate on these lower level predators and do not hesitate to kill and incorporate their battery materials. [Answer] # energy isn't what they hunt the herbivores for (or maybe not the only thing). AS far as I understood, the herbivores use plant matter as fuel to power themselves, and much like the carnivores, they produce small versions of themselves inside the internal "factory organs". Here's my problem with the system you described: where's the matter for that coming from? The plant matter seem to be treated exclusively as fuel to be burned, so clearly they aren't using that, so the herbivores are getting the materials for self-repair and for producing more young from somewhere else (or magically producing more, which would still require absurd amounts of energy to produce tiny amounts of matter). Therefore, given that many real herbivores actually lick salty rocks to get their dietary need of minerals and Based on the information you gave me, your herbivores have 2 forms of eating: 1-grazing protocol. They eat the normal plant life, grind it up, burn the whole thing, they do this until they've got enough to keep their batteries charged and function for a while. 2-feeding protocol. They graze again, this time at mineral deposits. Your herbivores need a lot of energy because their "digestive" system also processes both the organic and inorganic materials they eat to synthesize the materials and components they need to repair themselves and fabricate more young. This "grazing" can happen at mountain regions or something similar, but you'd probably need some way to recycle the metal and other components or just introduce more into the system (be it through meteorites that fall often, sci-fi magic or other mechanism). Now here's the thing: the carnivores eat the herbivores as you'd see in earth, but not because of some pointless instinct or necessarily because of energy. Rather it's because, unlike the herbivores, they can't process the raw materials. They need to have access to previously refined components to recycle into themselves and their young. So they eat the herbivores to get these refined materials. For all intents and purposes, apart from this limitation in material processing, your Predators could have their own ways of producing energy independently from the herbivores (example: Predators that rely on solar energy to power themselves, which could work nicely as mechanical counterparts for carnivorous reptiles, or simply things like predators that run on fission reactors and munch down on uranium reserves when they're not hunting. They can't process the raw metals into usable alloys, but refining uranium and other radioactive components isn't a problem to them [these couple be your mammals, since they'll need much better cooling mechanisms, but also be much more active than solar-powered reptile-bots]). Alternatively, they could simply gather specific components of the herbivores to burn in addition to the material recycling process. Maybe the herbivore's coolant is useless for the carnivore in his own cooling system, but works as a great source of fuel. [Answer] Carnivores burn their food just like anything else If we're looking at evolved predation, it's probably going to based on the previously existing herbivorous digestion system that extracts energy by oxidizing it for heat. Organic components like polymers or lubricants can obviously be burned as normal, but it's worth noting that refined metals are also capable of being oxidized in a way that provides useful heat. Alkali metals like magnesium and lithium (the latter is also a main component of batteries) are particularly flammable if crushed to a smaller particle size (i.e. chewed), as are most lanthanides and Aluminum. Making pure carnivores is slightly more complex since they need to be unable to effectively eat plant matter and so can't just burn their prey with regular oxygen. In this case, I would have these creatures use thermite reactions (using an oxide of a less reactive metal instead of atmospheric oxygen as the oxidizing agent) to generate heat from metals instead. This has a useful side effect of making refined metal from whichever oxide was input. So for example, an iron-based predator could use this reaction to get both energy and usable iron out of aluminum-based prey (provided they have some other method of collecting iron oxide to use in digestion). [Answer] The predation involves taking the "vital energy" of the prey and storing it for the use of the predator. Have the predators equipped with an energy storage (flywheel, dynamo and battery, pump and high pressure tank, heat reservoir, whatevs) and make the act of predation as coupling the engine of the prey to the energy conversion unit of the predator and driving the prey until it's exhausted. [Answer] We do not eat just for the calories in the food. The calcium in your bones and iron in your blood come from what you eat. > > The female units can 'eat' mineral compounds and other resources, which is what they use as the resources for their factories. > > > Males do it too. That's how machines overcome wear and tear. It just happens that the source of minerals for carnivores is herbivores. [Answer] Survival The attacked machines share a common trait that they emit something which causes discomfort, pain, or death: sound, EM radiation, heat, light; something. Omnivores Perhaps they gain sustenance from eating like flies: they secrete an acid which dissolves their food source — plant or robot — and slurp up the soup. [Answer] ## Hug of death > > a world where the creatures, though they look organic externally, are > actually mechanical in nature and when damaged reveal their mechanical > innards, with pipes pumping coolant instead of veins pumping blood, > the damage usually damaging the pipes and making them 'bleed' their > coolant, and some sort of energy acquisition system as part of their > bodies that necessitates the coolant being pumped. > > > > > I already have 'herbivores' that eat the naturally growing plants and > burn them in a furnace stomach and converts the heat energy to stored > electrical energy via water that has been previously taken in being > heated up and turning to steam to run turbines where a creature's > lungs would be and vent any excess steam by 'breathing out' if they > took in too much water earlier. > > > These facts in mind, I'm going to assume that predators have coolant and pipes for their systems as well, which suggests they have an "energy acquisition system" that they need the coolant for as well, which suggests they do have a power generation method of their own but can't do so through the burning of plants because being a predator in this world means you don't have the bulky furnace stomach or something along that line, but you presumably still have the steam power generation in your chest or whatever and do still take in water for that purpose as well. I'm also going to assume that the furnace stomach doesn't magically shut off just because the herbivore is in a state of dying. Let's have predators do what they tend to do best... Deal Damage. The damage dealt would make the herbivore bleed its coolant while still burning whatever the contents are of their stomach. This heat combined with the gradual loss of ability to cool off its systems will make the herbivore's systems fail eventually due to overheating. They basically bleed out and collapse, the difference being that they're now an extremely hot mass. Predators could use the extreme heat given off by a dying herbivore in a hug-like embrace and siphon it off to power their own steam generators, only stepping away once the herbivore is truly dead and not generating heat anymore, essentially leaving a cold and lifeless corpse. [Answer] # Nanobots This is what you need. To fully model biological systems, you need components that mimic biology. You have mentioned the following: a) plants are biological in nature b) mechanical herbivores eat plants c) mechanical predators eat herbivores Therefore the trophic cycle is: a -> b -> (c -> c) I would also like to highlight the following birth and growth: 1. mechanical creatures reproduce by the means of a small factory inside the female unit 2. the child unit is originally smaller than the parent unit, but grows in time 3. presumably, individual units can do some small damage repairs. Growth means that somehow, new compounds and parts are created inside a unit. This means that some basic semi-intelligent building blocks exist and they circulate around the body as to get distributed where needed. This means that a factory for creating these building blocks needs to exist. This doesn't mean that movement units, power units and battery/digestion units do not need to exist, although the animals might have to grow in some sort of moulding, where these units are turned off and extended. However, this means that you need some basic building blocks. In biology, these basic building blocks are cells, they can have various forms and functions. Some cells might do active digestion of materials, others will build tissues (your pneumatic system for movement), yet others will be used to quickly repair (or patch) damage. Once you mimic biology as closely as this, there is no requirement for any special way in which mechanical animal digestion differ from biological one. Herbivores can be just a complex fermentation machine that in their big fermentation vats (bellies) ferment biological matter and transform it into energy, but they also need to graze on inorganic matter. Maybe introduce mechanical plants instead? Predators are then essentially complex recycling units that recycle bodies of herbivores in some complex oxidative processes. ]
[Question] [ I’m making a fictional galaxy, and I want the inhabitants of this galaxy to be unable to calculate the age of the universe, I want them to be unaware of how much has already happened. I’ve already decided that most other galaxies once visible from mine, has already [passed beyond the cosmological horizon, and redshifted beyond detection](https://en.wikipedia.org/wiki/Future_of_an_expanding_universe#Galaxies_outside_the_Local_Supercluster_are_no_longer_detectable); leaving only a few thousand local galaxies, close enough to be gravitationally bound, to be observed. From what I can recall from school, the age of the universe is calculated by measuring the rate at which galaxies accelerate away from each other. So would it still be possible to calculate the age of the universe using only these local galaxies? If it is possible, when is the point (preferably before the heat death of the universe) where determining the age of the universe becomes impossible, or at least highly inaccurate? Or does someone have a different idea of how I can achieve this without throwing too many laws of physics out the window? [Answer] To make a long story short: The inhabitants of this galaxy might be able to determine the age of the universe by observing the cosmic microwave background, which exists throughout all of space. A couple of additional parameters need to be determined, too, but there may be at least a partial workaround. ## How do we calculate the age of the universe? A very simple estimate of the age of the universe can be found via the [Hubble constant](https://en.wikipedia.org/wiki/Hubble%27s_law#Observed_values_of_the_Hubble_constant), a quantity that determines how fast galaxies recede from us: $$t\sim\frac{1}{H\_0}$$ This is only an approximation, though, because the Hubble constant changes over time. A more sophisticated (and exact) technique that corrects for this involves determining the standard cosmological parameters. By this, I mean the various relative densities of dark energy, matter, and radiation ($\Omega\_{\Lambda}$, $\Omega\_{m}$, and $\Omega\_{r}$). We can then calculate the age of the universe by integrating using the scale factor $a$: $$t=\frac{1}{H\_0}\int\_{0}^{1} \Big(\Omega\_{m,0}a^{-1} + \Omega\_{r,0}a^{-2} + \Omega\_{\Lambda,0}a^2 + \Omega\_{k,0}\Big)^{-1/2} da$$ There are a number of ways to determine the Hubble constant and the density parameters: * Analyzing [baryon acoustic oscillations](https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations) * Examining the sources of [gravitational waves](http://adsabs.harvard.edu/abs/2017Natur.551...85A) * Looking at peaks and anisotropies in the [cosmic microwave background](https://arxiv.org/abs/1807.06209) * [Measuring gravitational lensing](https://arxiv.org/abs/1809.01274) * Studying the [Sunyaev–Zeldovich effect](https://en.wikipedia.org/wiki/Sunyaev%E2%80%93Zeldovich_effect) . . . and many others. We've recently seen discrepancies between some of the values derived by different methods (the so-called "Hubble tension"), which implies that our standard cosmological model may be incomplete, but they're nonetheless all valid. ## What your setup rules out We can throw out all methods that require measurements of objects at high redshifts, as those objects have, in your universe, disappeared beyond the horizon. Regrettably, this includes basically all the techniques I've described here. If you're looking for a time period at which it becomes difficult to determine the age of the universe - well, you picked a good one. No high-redshift sources are visible. One possibility that might remain is [looking for anisotropies in the cosmic microwave background](https://ned.ipac.caltech.edu/level5/Sept11/Freedman/Freedman5.html) (which I alluded to before), from which we can determine $H\_0$. Unfortunately, it happens that $H\_0$ is degenerate with the radiation density $\Omega\_{\Lambda}$ and the equation of state parameter $w$; that is, you need two of those to determine the other one. This means you can only constrain the relationships between these three. Of course, if there was an independent way to determine $w$ and $\Omega\_{\Lambda}$, you might be able to get somewhere. The situation isn't hopeless. $w$ tells us something about the composition of the universe by describing, in the case of our universe, the physics of dark energy. It's not impossible that non-cosmological experiments could help us narrow down $w$ based on the physical properties we'd expect from this substance. We could then partially break the degeneracy. Now, all of this assumes that the CMB will still even be detectable far in the future. The energy density of the CMB scales with the scale factor$^{\dagger}$ of the universe $a$ as $\varepsilon\propto a^{-4}$, which is significant enough that this far in the future, it will likely be of undetectable intensity (never mind that it will be redshifted significantly, too). ## Are stars a possible loophole? In a comment, [Mark mentioned](https://worldbuilding.stackexchange.com/questions/148369/is-it-possible-to-have-the-age-of-the-universe-be-unknown/148401#comment464590_148372) that you could use the earliest stars to measure the age of the universe. While this indeed gives you a sanity check of any other measurements you've made - if you see a star that seems to be 40 billion years old while your other methods tell you the universe is 13.7 billion years old, you have a problem - it's not going to give you more than an estimate. In our universe, for instance, stars didn't form for a hundred million years or so after the Big Bang. Moreover, these stars didn't necessarily form in every galaxy simultaneously; some might have experienced star formation later on. Therefore, measuring and modeling the oldest stars, while seemingly a loophole, has some problems. --- $^{\dagger}$ The scale factor itself scales in time as $$a(t)=\left(\frac{\Omega\_M}{\Omega\_{\Lambda}}\right)^{1/3}\left(\sinh\left[\frac{3}{2}\Omega\_{\Lambda}^{1/2}H\_0t\right]\right)^{2/3}$$ for a flat universe with dark energy density $\Omega\_{\Lambda}$, matter density $\Omega\_M$ and Hubble constant $H\_0$. Note that as $H\_0t\gg1$, $$\sinh\left[\frac{3}{2}\Omega\_{\Lambda}^{1/2}H\_0t\right]\approx\exp\left(\frac{3}{2}\Omega\_{\Lambda}^{1/2}H\_0t\right)$$ [Answer] The current 'measurements' of the age of the universe are actually measurements of some astronomical effects, that get mixed into calculations involving many constants. Most of what we know about the universe is (mostly implicitly) followed by '... if those values are indeed constant.'. Some weird effects are actually easier to explain when we assume the constants to be not that, i.e. slightly changing over time (or space). If your civilization realized that some important constant was actually variable, and a function of time that was not easily extrapolated (e.g. not a continuous function), their measurements might not be precise enough (maybe it would even be physically impossible to be precise enough) to pin it down, thus making the whole calculation impossible. [Answer] You can just have them be primitive. [![Roll safe](https://i.stack.imgur.com/Go8KL.jpg)](https://i.stack.imgur.com/Go8KL.jpg) Alternatively, they did have the knowledge and tech to do it. They just lost or broke all their satellites and telescopes. Edit: you edited the question to mention they do have technology. Alright, have them be surrounded by nebulae, such as the Eagle: [![Eagle nebula](https://i.stack.imgur.com/VSf48.jpg)](https://i.stack.imgur.com/VSf48.jpg) Or the Horsehead: [![Horsehead nebula](https://i.stack.imgur.com/kGLvB.jpg)](https://i.stack.imgur.com/kGLvB.jpg) Those are thick enough that we cannot see past them, at least not in every frequency. If your inhabitants are in a bubble of dust, they won't be able to measure the doppler shift of distant galaxies. [Answer] Your idea is sound. In the very far future when most galaxies are invisible and the cosmic background radiation has faded to the point of undetectability, evidence about the state of the early universe will be impossible to obtain at our current technology level, and some kind of steady-state theory may well be just as well supported by the available evidence. But remember that the visible universe will be very different from the one that we see around us today -- we're talking very far future, perhaps a trillion years from now. See [this article](https://dailygalaxy.com/2016/05/nasahubble-far-future-civilizations-will-be-clueless-how-the-universe-began-and-evolved-the-weekend/). [Answer] First why not, and then how maybe ... I'm not convinced this is possible for an advanced technological society capable of space travel. One of the things they have to figure out on the way to getting that developed is the General Theory of Relativity. Although Einstein gets all the credit for this publicly, that's a gross simplification of a lot of investigation and discussion and ideas and theories that helped, so a society is going to get to it. Almost as soon as you can do anything with this theory, people will inevitably start trying to develop a model of the universe. What we got (and this model is also pretty likely to be found by someone) is the [FLRW metric](https://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric). Expansion is what we found going on, but even in your scenario, they'll see effects in their "Local" galaxies (which won't be all that local any more !). They'll also become aware of dark matter and dark energy, because this affects the motion of galaxies and even the motion of stars in galaxies. Note even in the late universe when it's "dark" and they're all alone, even the fact that you are alone with nothing obvious to see will be useful data in terms of fitting it to a model of the FLRW type. Quantum theory is also going to be found. Again inevitably people will seek explanations for the origin of the universe and look to it to provide explanations. Like us they'll look for ways to combine quantum theories and general relativity (which we haven't quite managed yet :-) ). These will result in concepts that tell them to look at e.g. the relative distribution of different isotopes as evidence for their origin (this is one piece of evidence we use). So they'll inevitably find clues and look for explanations, and go looking for more clues to test theories and find more data. They'll keep looking until they get an answer, because if there is one trait I suspect all intelligent life shares it's going to be "unrestrained nosiness". :-) How to avoid this ... One word : Desperation. Give them a world that is in turmoil, always at war with itself, with an ecological nightmare that makes staying alive hard as blazes. That pushes resources and all the inquisitive people into more practical work (if necessary in chains). Also keep in mind that the main motivation for all that "going into space" stuff was not (in our case) pure scientific interest. We were building rockets to throw nukes at each other and science gave an excuse that didn't sound so insane. But in doing that we came extremely close to wiping ourselves out. So we (and they) could just as easily have gotten to space travel and promptly almost wiped out most of the planet's life, including ourselves. (And the option is still there, kiddies - vote for sane people, please :-) ). I don;t know about you but if e.g. the Cuban missile crisis had gone full scale nuclear exchange, none of us would care one iota about the age of the universe or studies to find out about it. [Answer] There are 3 factors that work together to tell us the age of the universe. 1. Redshift: Which we can use to map out the speed of the universe's expansion. 2. Age of Stars: By looking at the ages stars and ratios of stars, we can tell a lot about the universe's age from what we can infer from star life cycles. 3. The CMB: A uniform background radiation in the universe that is consistent with exploding superheated. While redshift is helpful for getting predictions of the universe's age accurately, no explanation that discredits it would actually make the age of the universe completely uncertain due to other factors. Ages of stars can also be tricky. The universe would have to be at least 100 billion years old for us to be able to observe the whole life cycle of every kind of known star. This means any universe younger than that (such as our own) would be easy to make assumptions about. While making a universe more that 100 billion yrs old seems to be the answer, by that point, you may still be able to calculate from what ratios of star types are left to make a good approximation all the way up until the cold death of the universe and final evaporation of all black holes. The best place to undermine our understanding of the universe's age is to mess with the CMB. We live in a part of the universe where we can only detect 1 CMB, where all matter is apparently expanding, and seems to have originated at the same time. This tells us there was a single big-bang at the "beginning of time", but as our instruments get better, we may one day discover other older or younger CMBs. The existence of multiple bangs could knock out the very concept of the beginning of time. If we find out that our universe intersects another bang, then it could be inferred that what we know to exist today is just part of a greater pattern of big bangs that have been going back for unknown quadrillions of years well beyond out powers of observation. [Answer] Make your universe highly anisotropic. First, I should start with the disclaimer that general relativity is a very complicated subject, and while I have a cursory familiarity with it I am in no way an expert, so take this with a grain of salt. With that being said, the idea behind this is that in general relativity, the coordinates that someone measures depend on the path they take through space and time. This is because in general relativity, spacetime is described by a manifold, which is a fancy way of saying that it seems normal and flat close up, but globally it can have some funky structure. The classic analogy is how the Earth looks flat when you're standing in west Texas, but if you walk long enough in one direction you'll end up where you started which is a decidedly not flat thing for geometry to do\. The difference here is that while the Earth is embedded in 3 spatial dimensions, spacetime isn't embedded in any higher dimensional, flat space. This may not seem like a problem at first, but it actually causes issues if you want to define coordinates that everyone can use. To see why, say you were a two dimensional creature who lived on a spherical manifold like the Earth, only it wasn't embedded in a flat 3D space you could interact with. Like any good, scientifically minded 2D creature, one day you have the thought that life for everyone would go so much smoother if everyone on your world could have some common way of giving directions. So, you grab a stick, point it in a direction, and secure it firmly to the ground. You then declare this to be the standard direction everyone should use for giving directions from now on (let's call it 'weast'). Of course, a standardized direction like this is pretty useless if it's only in one spot, so you need a way for others to 'sync' their directional sticks with yours and then take them to new places across the world. The syncing part is pretty easy-- they just need to bring their stick next to yours and point it in the same direction. They need to be careful transporting it though. Clearly, if they travel back to their hometowns doing doughnuts in their 2D mustangs, the stick is gonna be completely disoriented by the time they arrive. Being the smart scientist you are, you come up with a solution: any time they're walking in a straight line, they should keep the stick so that it has a constant angle with respect to the direction they're walking, and any time they make a turn, they should rotate the stick in the opposite direction they turn by the same amount. The math for this is straightforward, it's just some 2D Euclidean geometry after all! Content, you lean back and wait for the thank you letters to start rolling in. Much to your dismay, several days later agitated letters start pouring in from around the world. They complain that the different messengers they sent with sticks came back with them pointing in completely different directions. But how can this be?! Well, since we have the luxury of living in a 3D world, let's look at this from the viewpoint of a sphere imbedded in 3D space. Say both the messengers start on the equator and are headed to the north pole. If one of the messengers travels directly to the north pole along a meridian while the other goes a quarter of the way around the equator before heading up a meridian, when they get to their destination, their sticks will be pointing perpendicular to one another! Here's a picture to help illustrate in a less confusing way: [![enter image description here](https://i.stack.imgur.com/Rffqr.png)](https://i.stack.imgur.com/Rffqr.png) It seems our flat friend has made a fatal error-- he was doing math for a flat world, when he lived in a curved one. In fact, once space is curved it is impossible to come up with a way of translating a coordinate system in a way that doesn't depend on path-- this is the subject of parallel transport and connections in differential geometry. It may be tempting to say that there is a consistent way of transporting coordinates by considering the flat 3D space the sphere is sitting in, but remember that manifolds aren't required to be imbedded in higher dimensional space. Even if it were, the 2D aliens have no way to access this space to make measurements, so it's a moot point. Finally, getting to the point: general relativity works in a very similar way, only it complicates things by getting time into the mix as well. In relativity, time is not an absolute coordinate. It can get mixed up with the spatial coordinates and the end result is that much like the 2D messengers, two astronauts carrying clocks can start with them synced and end up out of sync when they arrive at the same place. So how is it that cosmologists are always talking about the age of the universe? Well, they use something called the FLRW metric which describes how coordinates evolve in an homogenous, isotropic, expanding universe (basically all those words mean that the universe is modeled to be the same everywhere). If you look at the sphere picture, you might be able to work out that the amount the arrows are out of sync is positively correlated to the percentage of the sphere's surface area the two paths contain. What this means functionally is that if the curvature of spacetime is not that great, or our two astronauts don't diverge far in their paths, then the proper times they measure will not be significantly different. Since the FLRW metric describes a homogenous universe, it is "easy" (at least by GR standards) to tease out a time coordinate that is useful for everyone as long as a few conditions like low comoving velocity are met. It just so happens that the assumptions of the FLRW metric are a good model of our universe, but this doesn't necessarily have to be the case. One could imagine a highly anisotropic universe with no CMB, many very dense collections of matter in some parts and huge voids in others, all moving at relativistic speeds to one another. In such a universe, giving a single useful age of the universe would be difficult because there would be so much path dependence and the conventions taken would be so abstract and unintuitive. Of course, this kind of universe might not be very conducive to life, but I'll let someone else sort that out as I've written enough already. \ Ok, technically this isn't true because tori exhibit the same behavior and have no curvature but you know what I mean [Answer] It is entirely possible that what we call Big Bang is not a one-shot event (it is only assumed that this is the case, and tbh I don't understand why this assumption is taken for granted), but an ongoing process, and we only know when the "local" part of the Universe came into existence. So, if a civilization has assumed something else, eg. there is -- let's call it -- the Source that has been spewing the Existence maybe for eternity. They will definitely assert that age of Universe is not known and cannot be known unless the Source itself can be studied in depth. Addendum: oh, someone does not like this controversial comment, again, without saying why. I wish they had the balls to say why, because I can actually justify this. I would like have a chat with them. ]
[Question] [ This question happens in the same universe as my other questions: 1. [How should a country introduce a constructed language as the official language?](https://worldbuilding.stackexchange.com/questions/63953/how-should-a-country-introduce-a-constructed-language-as-the-official-language) 2. [How many years could you trim from schooling?](https://worldbuilding.stackexchange.com/questions/65044/how-many-years-could-you-trim-from-schooling) 3. [Could large but sparsely populated country control its borders?](https://worldbuilding.stackexchange.com/questions/65678/could-large-but-sparsely-populated-country-control-its-borders) TL/DR My story happens in a country which is large by land area, relatively well off economically but with a small population. The country is ruled by an autocrat who is keen on social engineering. The problem for our Dear Leader are those pesky liberals asking for silly things like: Independent media, rule of law, equal rights for women, recognizing minorities, releasing political prisoners etc. Our Dear Leader already [slashed](https://worldbuilding.stackexchange.com/questions/65044/how-many-years-could-you-trim-from-schooling) all those unnecessary fields where liberal professors brainwash innocent students, such as the arts and humanities. Unfortunately it turns out that some people still indoctrinate themselves with the ideology of our enemies. Though our Dear Leader never shied away from trying to help liberals see reason by either the re-education through labor program, or failing that the good old-fashioned murder, he noticed that families of the lost sheep aren't too appreciative of his efforts . Unfortunately population of our country is very small, so helping them perceive the wisdom is out of question, at least for now. Is there any way to encourage those pesky liberals to leave the country? Our Dear Leader is ready to spend money and help them champion their causes somewhere else. They could protect the environment all they want as long as it's in some other country. The families will be happy that their loved ones are safe. And our Dear Leader would happily sign mining contracts for the glory of our nation. IMPORTANT Dear Leader wants people who dislike government policies to leave the country, preferably somewhere far away. The country has a reverse [Iron curtain](https://en.wikipedia.org/wiki/Iron_Curtain) where everybody is allowed to leave but nobody is allowed to get back without permission. The industries are very capital intensive, there is no benefits in political prisoners harvesting woods in the [Taiga](https://en.wikipedia.org/wiki/Taiga) when the same job could be done by contractors using [heavy forestry equipment](https://www.deere.com/en_US/industry/forestry/forestry.page). Entrusting 1,000,000 forestry equipment to intellectual who hates the regime is not a good idea. Political prisoners tie guards that are needed elsewhere while providing zero benefits to the country. Killing them enrages the families of the liberals, who ask for clemency. [Answer] The fictional great leader could take some pointers from history ... * Allow liberal artists on a concert tour abroad, then [revoke their passport](https://en.wikipedia.org/wiki/Wolf_Biermann#Deprivation_of_citizenship). * Put liberals in jail, then generously allow them to leave. Perhaps there are even [concessions](https://en.wikipedia.org/wiki/Trading_of_East_German_political_prisoners) for doing so. Those two examples worked under the peculiar conditions of the divided Germany, where West Germany claimed that East Germans were their citizens, too. But perhaps something could be made from it. Make it possible for the most obnoxious intellectuals to travel abroad, where rank-and-file workers cannot? Make it possible for them to take their immediate family, but no more? [Answer] ## The Three-Step Program to Remove Your Political Enemies ### 1. Set aside some land for a liberal state No matter how you try to force the population out, they will need a place to be forced into. Saying "just go" without offering land to go to may result in a revolution - or international backlash. This place must be * Nearby, to minimize the costs of travel. Lower costs reduce the probability of revolution * Reasonably under your control, so they don't cook up ideas that could harm you under a foreign power * In a place that's easy to cut off (perhaps on the border, or in the mountains, or on an island) * Fairly liberal already, so the "useful" population isn't upset about losing their land Provide this land as a "liberal state" and strongly suggest that those with opposing political views should move there. They will be able to make whatever political choices they choose as long as they remain loyal to you, should you need them; suggest a democracy, perhaps. ### 2. Motivate the liberal population to move there In order, follow these steps to motivate your settlers: * Offer to pay the costs of travel and housing * Raise the remaining people's taxes by 10% each month * Advertise to the public how liberals threaten the cohesiveness of the government; make them uncomfortable and disliked where they are, and describe the silver lining of the place where they could alternatively be. * Fine those still present if they do not leave (or if they don't close their mouths) * Criminalize having public "anti-establishment" or "anarchial" or "destructive" or "chaotic" or "unusual" political affiliations. Say that such beliefs impair the nation's ability to function, to reach greatness, etc. and that everyone needs to work together or move to the Liberal State in order to benefit the people. Punish "criminals" with deportation or incarceration. * Militarize if there are still problems. ### 3. Isolate the state Grant the government of the Liberal State independence, under the condition that you can continue deporting criminals there. Include some valid, true criminals in the mix to promote anarchy. Keep some of your agents in its system to monitor its activities. Define a clear border, and cease economic activities across it; a wall, trench, or canal may work well. Make emigration one-way. [Answer] Given the description of your nation as being large, sparsely populated and with lots of land which is marginally habitable, the simple solution is to revive the Soviet practice of "internal exile". One thing which seems pretty common throughout history is despotic regimes spend a lot of time and effort keeping people trapped within their borders, even when it would seem more logical to simply let dissidents leave. Presumably, like most socialistic paradises, the population is constrained by travel through tight control of transportation and the use of internal passports or other documentation, so rounding up dissidents and their families and shipping them past the Ural mountains or whatever the demarcation line in your fictional nation is should suffice. They are not going to be able to wait at the train station for a ride out, since you control the train schedule (trains only arrive to bring more dissidents, or are freight trains to extract mineral or other natural wealth), and no one is getting aboard without proper paperwork anyway. This has the added benefits of providing a literally captive labour pool for whatever needs to be done "out there", preventing dissidents from communicating with the rest of the population and also preventing them from finding a safe haven in foreign territory to arm and train for revolution against you. (This explains the obsessive efforts of the Soviet Union to track down dissidents and "white Russian" groups who had fled the borders of Russia and either kill, kidnap or subvert them in the 1930's). So people are not going to be encouraged to immigrate, they are just going to be "encouraged" to move away from the population centres, but still provide labour and maybe other value to the regime somewhere else. [Answer] How to force opposition to emigrate? 1. Create thought leaders, people who the average person trusts to shape their opinions. They must show people that they match their opinions for most things in order to win their confidence, and then drop hints to move them towards distrusting liberal. You must have thought leaders for the opposition. They will be your trigger for emigration. 2. Create multiple information sources. So you need agents on news papers, broadcast journalists, social media. They must produce a coordinated campaign of information so that people believe they are forming opinions based on a broad range of inputs. 3. Create an opinion of moral license. People should feel that by condemning opposition messages they are licensed to act badly. The average person can engage in bullying and emotional outbursts while feeling justified. 4. Identify opposition traits as shameful. The goal here is to introduce a descriptor that is fairly neutral, and associate it with shameful things. So you may call someone 'highly educated' which will signal your folks 'unrealistic dreamer' or 'closet revolutionary'. This reduces conversation by creating a subtext the opposition can't deal with. 5. Focus news coverage on examples of opposition viciousness and minimize or gloss over other stories. This creates a narrative of scary violence that will fuel over reaction in your supporters. Your want a lynching to show the opposition that you can barely hold back the righteous anger of the public. 6. Thought leaders for the opposition should threaten emigration to Canada (or some other utopia). They will lead the exodus. 7. Finally, you need a triggering event. You need a riot by the opposition, an attempted coup that you you can blame on the opposition (see [false flag](https://en.wikipedia.org/wiki/False_flag)) You want some violent event that will let you draw a line under the situation and trigger 'positive action'. Mass deportation is one option if you have enough rail road cars. You may want to examine the history of India around the time that the British were forced out. At that time, Muslims and Hindus were at odds. Eventually, Pakistan was formed as a place for Muslims. Not all Muslims left India, but many of them did. Note well the current relationship between India and Pakistan. [Answer] Assuming that country is rich enough, that people would not emigrate because of economical reasons... Such people would actually be already generally willing to leave... The problem is that without proper persecution other countries may see them as economic emigrants who can be deported back, instead of people seeking political asylum. Make quite a few laws which violation would be treated as treason. Then, because of mercy offer such people as a way to escape any punishment to be stripped of citizenship (thus no longer expected to be loyal). Finally deport them abroad with documents necessary for political asylum. Be extra merciful and let some state funded charity to help them transport their left behind property afterwards. If the procedure is organized properly, then opposition members deface poster of the Leader and incriminate themselves on the nearest police station. Police give them questionare on which they can pick their crime from the list, refuse to rat any co-conspirator, select country which they would like to be deported and list whether their property should be stored in secret police storage facility, auctioned or given to selected family members and friends. ]
[Question] [ I have a creature who harvests resin from trees as a building material. These trees are similar to those on Earth, but not identical (I.e. there is biological wiggle room). I would like the creature to be able to cast this resin into shafts for spears and bows. It appears that epoxy resin can be used for this purpose, though it’s likely resin from Earth’s trees would be a poor building material, and I would prefer if this resin remained biodegradable, which most synthetic resins are not. The resin likely contains cellulose, which could be processed with the resin to strengthen it. For the sake of the question, the creatures are human-sized and the weapons are used in the same way we use them. As far as use in combat/hunting, could this resin work as the primary component in primitive weaponry? Could it be superior to wood? While the process of manufacturing the shafts is also an interesting subject, I’d like to save that for another potential question and have this one purely about effectiveness. [Answer] # The Plywood Jungle: Biology is capable of amazing things. But it doesn't always behave like you want it to in real life. Thank goodness for the power of the pen. There is nothing physically or biochemically impossible in what you want to do. But the resins by themselves are unlikely to be strong, per se. Your best bet is to make the resins as the glue of various composite materials. People have made thin veneers of wood for thousands of years and glued them to surfaces. But people didn't really start figuring out that you could recombine pieces of wood into fixed shapes until they started making plywood. Your species is simply avant-garde. Maybe the wood available to make tools is not very strong, or not very hard, or not very straight. People were very picky about what kinds of woods they would pick to make tools from. But people started to use [glue derived from trees](https://baynebox.com/news/the-history-of-glue/#:%7E:text=The%20oldest%20known%20glue%20used,spear%20stone%20flakes%20to%20wood.) 200,000 years ago. For your purposes, the difference between glue and resin is semantics. Your species is what people say [Stradivarius](https://en.wikipedia.org/wiki/Stradivarius) could do - literally gluing wood together to make "super-wood." While people dispute Stradivarius, there's no disputing the potential of composites. They can make thin veneers of wood (or maybe even leather), steam them, roll them up with your resin, and make new wood in whatever shapes they want, to the lengths they want, hard or soft depending on the desired consistency. A different resin seals the wood against moisture. After that, you need to figure out what your species needs this process for. To make wood the right shape? The right hardness? To make more flexible wood? To make wood composites to make stronger [(composite) bows](https://en.wikipedia.org/wiki/Composite_bow)? A mix of materials (like horn, bone, stone, even grass) can get you tools of most any desired function. But in the end, your species just got lucky to find organisms that produced the substances that matched their needs. [Answer] Resin from the Xylonean tree combined with the acidic fruit juice of Tsaylean bush causes resin to harden to become a strong chitin like substance. Instead of using always hard material that is difficult to process, your folks will use the resin, shape it, then strengthen it with the additional component. It is also possible to dunk the material in activator just enough to keep the core soft, object made of it will be much more durable. Since the biology of your world is different, there is no reason that this cannot happen. [Answer] I think @DWKraus is on the right track with composites. Looking at actual composite bows, they are made from a combination of a thermoplastic or thermoset resin with a fiber or filament like glass. I think you need to mix the natural resin with a strong natural filament like spider silk or a natural fiber taken from a vine or similar plant. [Answer] The [Rift War Saga](https://en.wikipedia.org/wiki/Magician_%28Feist_novel%29) utilises resin or, rather, lacquered wood as an alternative weapon and armour. As with resin in real life, you could incorporate a process for the conversion of the tree sap to a final product, such as the creature has a much higher than normal acidity to its saliva, so either regurgitating or spitting on the sap forces a reaction when it is exposed to air. As an alternative, small quantities of the sap could be combined with pouches at the back of the creatures throat that build up gas or air and can be used to fire this as a weapon, too! This does, of course, depend on how reliant the species is on the specific tree. (Therein lies a weakness). [Answer] Resin weapons... Since you mentioned some biological wiggle room and an alien planet with environment conditions close to earth, it kidna depends on the resin types and qualities. Lets categorize some the important aspects to determine the effectiveness of a weapon. One: Base material. You can literally grow more trees to get more resin. Carrying seeds and setting up a new village, with resource you literally grow from earth, would help a lot when it comes down to harvest base materials. Two: Skill or tools. Depends on real or hypothetical resins, skill sets may require weaponsmithing, gardening, and maybe a bit herbalism to concoct the correct substance. Hardening the resin is an easy process, and sharpening the weapon, adding the handle and other properties can be handled while the resin hardens. Molds or hanging the resin is also an easy method. This part, depends on your resin and processing methods. Three: Properties of the material. Maybe resin could be hard, flexible, and light. Which is good for making weapons and armors. Maybe it is too heavy, so only small weapons could be made. Maybe it is brittle, so only arrows and small daggers could be made. If the resin is strong, maybe making a shield from it and hiding behind could save lives. Four: Long-term uses, or durability. If your cheap sword breaks after two days, no matter how easy it is to make, it will cause problems. Handling the weapon may requrie special training, which could require skillful warriors. And reducing the effectiveness. If your weapon keeps its best qualities a long time with less effort, it will be quite an effective weapon. Because, just getting one could help you a long time. Metal weapons require care. Sometimes special materials. Or certain regular actions. If your resin weapon can keep itself a long time with less requirement than an iron weapon, then it can even surpass the metal counterparts. All these properties will be important to determine the cost, time it takes to "forge" a weapon, and how widespread it will be. Or in other terms, how effective it would be. From my understanding, it could be superior to the wood if the resin at least as good as wood. Because, for wood, you either need good parts on big trees, or you need to chop a big tree, cut it to pieces, and use the chopped off wood. For resin, you don't even need to cut the wood. Depends on the resin and obtaining method, you may need a small forest, cycle through trees to give them time to heal and make more resin, collect enough resin and work on that. Obtaining base materials is easy, so even small tribes with small men power can get some. If resin can be used as, even a one-use weapon, can be more effective than wood. Due to how easy it could be to access it and make weapons from it. Carrying a few resin javelins or arrows made from resins could be superior to wood. But it all depends on how good resin is as a weapon. Since, there are several types and mixtures can offer even more options, it is hard for me to come up with a clear answer. [Answer] There are good answers here already, and yes, proper composites would work best, but may need better tools to be build, so here's my spin on it. Thus let's look into Types, Performance and Curing of resins. ## Types of resin There are natural resins that get hard and there are natural resins that get rubbery. Commonly they loose water and terpentines in the process, but they may also polymerize. Hardened resine doesn't rot quite as easily, and may become amber under certain circumstances. ## Performance and Usage If you have mainly soft wood, it may outperform that. HOWEVER: Keep in mind that in the comparison "laminated wood" (plywood) vs fiber-composite vs pure resin, the pure stuff will lose as compounds are usually superior. Plywood is far more difficult than fiber composite, as you must get it very even. If your resin doesn't really harden, but only gets semi-hard and sticky, it may be better than fiber composite. For hard resin, fiber composite is probably the best to build, as it is easier to form and probably stronger as well. Also: While if used like glue, plywood is an option, the question arises, why not to use the wood itself. A possible reason might be your plants: They might have good wood, but bad growth patterns. Making a composite may enable you to form it appropriately. If (partially) transparent, the resin might be used for decorative reasons. Especially on spears and bows, if you use fibers for the composite, you might form it to build some holes in a decorative pattern, which may be filled with the resin and thus still provide (some) compressive strength. It might also be used as shards-section in a weapon. If you have a spear, and the cured resin is a bit brittle, one might use it to attach break-away tips or to outright build a shard-tip to maximize damage to prey or opponents. ##### Sharpness of your weapons might also be a reason: If we argue that you have only chalky stones, you might have a hard time getting a proper point to your spear. Especially when you have no access to hard woods. A bone will crack, yes, but it will not give a sharp edge. As the stones are soft, they won't give proper blades either. Also they are to soft to grind bones or wood to a point on them. You may break of strong-ish branches, but again the end will feather out and be difficult to be ripped in a way that produces a point. The result would be a spear with a rather meek tip. Hard resin or rosin to the rescue: you create a spear the old way, then dip the tip into hot rosin and let it harden. If you left it hanging tip-down for hardening, you already got a better tip than before. However, one may improve on it, if the resin is also at least a bit brittle. The tear-drop tip may be broken of and (at least for many types of rosin on earth) will form a semi-sharp to sharp edge. (Rosin is usually quite amorph and thus may crack building sharp edges. Think of rosin as a bit like a mix between the strength of most plastics and the shard production of glas.) ## Curing your resin At some point you'll want to cure your resin. There are a few options, each with their pros and cons. ##### Chemically Cem Kalyoncu argued you might mix two or more saps and resins for them to react and harden. On its own, this would probably result in inferior plastics, caused by impurities naturally occurring in the saps / resins. HOWEVER you might wash it during reaction, getting rid of impurities and thus better quality. Alternatively you might cure with white ash or charcoal, but again washing might bring improvements, as might folding. Two possible settings: 1. Mixing results in granulate matter, which after washing may be used (probably by melting it) 2. Mixing results in something that feels like a mix of bubblegum and honey. While washing you fold it and stretch it, rinse and repeat. The result may be formed like clay and will slowly harden. ##### Air It might well be, that a certain plant has sap that will harden when exposed to air to clot a wound. The reaction would stop close below the surface as new air has a hard time reaching in. Thus your craftsmen might pull it apart and fold it, or if it's thin and runny, whisk it to bring it in contact with a lot of air. It would probably build a gooey foam that will start getting warm. You could then form it. Again, working it in water would keep it cold (probably slowing down the reaction), clean out impurities and might help removing the bubbles. ##### Light Similarly, a plant might have sap that hardens when exposed to sunlight. Thus your workers might harvest it at night time. If transparent, this might be casted and left in the sun for a few hours or days to cure. For a compound, one might wet fibrous material with it and hang it in the sun to cure; subsequent layers could be added by painting them on. NOTE: Neither the light nor the air version will work terribly well with cross-laminated wood. Air would probably work better, as it might get saturated before hardening, but both would need fast working. So far, the results will most likely NOT compost. Let's address that. ##### Thermal curing You may boil resins to make rosin / colophonium. Rosin is hard and plastic like. Basically it is the remainder of resin, after water and terpentines boiled away. Furthermore there are rubbery resins (usually not from the plant sap, but from the fruit sap) that work to make it flexible (latex, kauchuk, plum-resin). By mixing these resins and varying the boiling times the rosin may be customized. The resulting rosin will compost, but not super-easily. Of course adding fibers would make it far stronger, but (if not overdone) it could be formed to build transparent sections. ]
[Question] [ Let's imagine we have a disease. Call it the "Thought Plague". It has all the symptoms of a normal disease; in fact, let's use COVID as our symptoms baseline. However, this disease has an... unusual way of spreading. It spreads by thought. As in, if you know about it, you catch it. Not only that but, if you catch it, after the incubation period of 14 days ends, you are more likely to tell other people about the disease. Because of this, methods, as we use now, don't work; if you tell people to not tell people about the disease, everyone is infected. How can the disease's spread be prevented? * Assume the people trying to stop the spread of the disease have complete control over laws, etc, but not whether people follow them. * The likelihood of you being infected is based on how much you know about the disease; if you just know the name, it spreads roughly 1% of the time; if you know how it spreads, 5%, and so forth. * The organization attempting to stop the spread is still susceptible to the plague. * I will add more info as needed. * If it seems impossible, you can remove or add limitations until it is possible to prevent the spread. * Like COVID, once you catch the disease and are symptomatic, you are free from it in about 14 days. After this, you will not catch it again. The disease doesn't mutate. [Answer] # Misinformation: This disease has to follow some kind or rules, or else nothing can stop it. It spreads as a telekinetic meme, able to somehow manifest physical disease as a result of thought. The more you know about it, the more likely you are to get sick. This is VERY problematic for those researching it (who must know the most about it). But what if you want to LIE about the virus? It has a name, which came from somewhere. Names have power, so give it a different name. Novel memetic coronavirus becomes COVID22 to researchers, which can then get advertised to the public as the psychic monkey pox (even though it has nothing to do with monkeys and isn't a pox). Lie about the symptoms. It causes fevers, so televise that it causes chills. Anyone who has a fever has something else - the flu, perhaps. You could work directly with someone infected, and they would tell you they had the flu. So while they are telling you about the disease, what they know about it is wrong. And since the flu is a real thing, knowing about someone with the flu won't make you sick because you know the flu isn't the psychic monkey pox. The sick will help spread the disinformation themselves, because everyone knows the psychic monkey pox is spread by the hate of the sick people towards those around them. If you catch it, it's because your neighbor who was sick lied to you out of spite. [Answer] There are actual mental illnesses that do work like this in the real world. Anorexia might be the best example. One of many eating disorders, it was unknown in other cultures until recently. In east Asia in particular. Instead, there was a similar eating disorder that was more typical. But as those countries became westernized, the native eating disorder became rare, and then disappeared almost entirely... having been replaced by anorexia. Youths there became anorexic only after learning of its existence elsewhere in the world. Another example would be adolescent suicides. In certain places, suicide clusters will occur. It is theorized they spread by "contagion", such that if a teenager hears about a suicide in their community, they are more likely to commit suicide themselves. At that point, now there have been two such, and other teenagers are at an even higher risk of doing the same. It tends to snowball that way. This might even be why people instinctively hid the fact that a loved one had committed suicide in ages past... it wasn't so much shame/embarrassment even if it presented that way, but an evolutionary adaptation that interrupted this contagion and slowed or stopped the spread. Obviously, these mental illnesses aren't quite as virulent as your fictional disease. You're positing some ideal mental pathogen with a short incubation time (but not too short) and some insanely high R nought. In such a scenario, you will see the sorts of things you've seen about thosesuicide. For instance, some newspapers refuse to report about such suicides for fear that it will inspire more, out of a sense of journalistic ethics. You might even see a longer term adaptation where people deny the existence of such a disease, not to mention all sorts of euphemisms about the "thing that shall not be named" and so forth. The efficacy of these measures will of course depend on the exact mechanism of the disease, how it affects the human mind, and so on. But those are the sorts of measures that will be attempted. [Answer] Treat the sicks with opium: they will be too lost in their artificial happiness paradise to talk about it to anybody else, with the interesting side effect that, since > > if you know about it, you catch it > > > if they somehow forget about it, they might even heal from it, and be just left with a dependence from opium. [Answer] Tin foil hats All you need to do is block the signal, and as we all know that tinfoil hats prevent the government spying on your thoughts so they should also be effective in stopping your thoughts leaking out your brain. [Answer] Forgetaboutit! Hopefully scientists can develop a memory-erasing device, a la Men in Black, while remembering how the device works. ]
[Question] [ Some fish [mouthbrood](https://en.wikipedia.org/wiki/Mouthbrooder). Some amphibians mouthbrood. Crocodilians carry their babies in their mouths to water. Is there a reason why there are no instances (that I know of) of terrestrial animals that mouthbrood? Why can't there be pelican babies in pelican beaks or chipmunk babies in chipmunk cheeks? EDIT: I want to have plausible mouthbrooding terrestrial creatures, but worry there might be some glaring misadvantage that I am missing to having that trait in a terrestrial creature. The world of these creatures would be much like our own. The basic picture, for a big branch of terrestrial animals, would be a throat pouch where babies would grow until fully ambulatory. For the more primate-like animals, the baby would be held to rest against their chest, much like we front carry our babies with baby slings, leaving the parents' forelimbs free to swing from one treebranch to the next. Is that too ridiculous? [Answer] The best candidate would be a snake. Mouthbreeders have big mouths, and generally catch prey whole. There are nothing that feeds by nibbling that holds young in the mouth. There are no insects or non vertebrates that I know of that have big mouths like this. I suspect evolution favored big, gulping mouths first and then selected for mouth breeding after. The plausible terrestrial mouth brooder is snakes. Snakes catch and eat prey whole. I found a very old paper which really dug into depth about the possibility that snakes would take their young into their mouths to protect them. [Do Snakes Swallow their Young?](https://www.jstor.org/stable/2447131?seq=2#metadata_info_tab_contents) > > "Sirs, — A short time since I was in Condersport, Pa., in whortle- > berry time, and a man who had been out berrying stated that he > suddenly came across a Rattlesnake with her young, some twenty-six, \* > about her. She immediately opened her mouth, and instantly the whole > family of little ones went down her throat. Do you believe it? Is > that the nature of the Rattlesnake? — H. M. S." > > > Ultimately it would seem that snakes do not swallow their young. But it is not implausible. Snakes can swallow and then regurgitate live animals (as discussed in linked paper) so the young snakes could re-emerge. Rock pythons do provide some maternal care so that is not an impossibility for snakes. Probably these would be the viviparous snakes although not necessarily - crocodilians lay eggs and then provide maternal care for the hatchlings and so snakes could too. Also, young snakes have a good shape for this maneuver. [Answer] First of all it's a matter of size. Newborn fishes and crocodiles are small enough to fit in their parents' mouth. Despite this, some terrestrial animals use their mouth to carry around their babies: never seen a cat or a lion moving around their cubs by gently biting behind their necks? Still, those cubs are too big to fit in the mouth. [Answer] Caveat: I'm not an evolutionary biologist. It probably has something to do with the fact that non-aquatic animals breathe through our faces, whereas most aquatic animals have gills. My (cursory) [reading on mouthbrooders](https://en.wikipedia.org/wiki/Mouthbrooder) indicates that most either do not feed while brooding or feed very little. This indicates to me that the mouth is almost or completely blocked by the brood. Even if a non-aquatic animal could survive a brooding period without eating or drinking water, we can't live without air. Anything that could put pressure on or potentially block the throat is dangerous to us. So, if you want non-aquatic mouthbrooders, you might have to give them gills. It would be difficult to justify this from an evolutionary standpoint, however, since we spend most of our lives not brooding. Any orifice in the body is an opportunity for infection, which is why evolution favors fewer rather than more; look at how many species have cloaca instead of separate orifices for urine, solid waste, and reproduction. Mammals are basically the exception here, all other vertebrates favor cloaca. So, to develop a separate orifice (or two) for breathing during the few months out of their whole lives when an animal might be brooding, rather than using the perfectly serviceable orifice\* in our faces, would require some strange kind of evolutionary pressure that made either gills or mouthbrooding absolutely essential. Aquatic animals, of course, developed gills because they have to filter oxygen out of the water. Perhaps there is something in the atmosphere on your world that the non-aquatic animals need to filter. This might give justification to the development of gills and, in turn, the feasibility of mouthbrooding. \*I am here referring to the throat. Technically we breathe through three orifices; the mouth and two nostrils, but since they all connect to the throat, I am considering them as a unit. [Answer] There are 2 advantages that I see aquatic mouthbrooders having over terrestrial: 1) Aquatic mouthbrooders are buoyant. The added weight of the young in the mouth is not noticed by fish because the weight of young aren't any different than the water already in their mouths for "breathing" through their gills. A land animal would have to have strong neck/back muscles to continuously carry their young in their mouths. This limitation in land animals may also cause them to get caught off guard by predators if they could not turn their heads fast and readily respond to threats with their teeth. 2) Land animals have to drink water regularly. Aquatic animals consume a small amount of the water that they are "breathing" through their gills and process out the salts. Conversely, land animals, save for camels and some hibernating animals, have to drink water regularly as well as eat which would hinder raising young. I think that the need to drink and fend off predators are two major reasons that mouth brooding in land animals isn't as plausible. There are animals that do carry their young in a pouch, however, those are marsupials. Kangaroos have a pouch in their lower bodies for carrying young which frees up their heads for eating, drinking and scanning for predators. The pouch also puts the joey in a lower center of gravity where the strong leg muscles can easily carry the added weight. [Answer] As has been mentioned so far, the young of a mouthbrooder are born tiny and the mouth of the parent is large. So, if hippos had litters of tiny hippos or if they gave birth to tadpoles that needed time to grow larger before metamorphizing into baby hippos then mouthbrooding would be a good way to protect them. They could carry their brood in their mouths across the savannah during dry seasons. I imagine momma hippos and daddy hippos humming tunes to their mouth-broods and gargling songs to teach the ways of the hippo. ]
[Question] [ Recently I was talking with a friend of mine on fantasy stuffens. I brought up that its interesting that dwarves are rarely in the desert and he immediately listed reasons why the dwarf build is bad for the desert: Short stumpy legs are bad for the desert and horrible heat dispersion made worse by the massive beards. But how could the common fantasy dwarf (short stocky and with a big beard) adapt to a desert environment? What kind of physical changes would be necessary for this change in environment? Note: I don't want to lose too much dwarfiness so if possible I'd like to retain at least being stocky (although thinner then the usual dwarf) and having big beards. The social and architecture changes will be a later post. This is a slow gradual change from the proto dwarfs that wandered into this desert so you have a large time scale to work with. [Answer] Primary issue with living in the desert is lack of water. Dwarven build is well suited for storing water. Their round bodies with healthy amounts of fat should store lots of water. Low surface area should reduce loss of water. Dwarfs are generally said to like working at a forge, which implies they can tolerate hot conditions fairly well without sweating insane amounts of precious fluid. Sleeping underground where the temperature is stable during the day is a common adaptation by desert animals. Dwarves are excellent at digging and prefer to sleep underground anyway. Your desert would be full of burrows where the dwarves sleep during the day. Desert animals commonly prefer to be active during the night when it is cold and less water is lost. Dwarves see in the dark and their wide forms are well suited to resisting the cold. They'd adapt to being nocturnal very well. In short, dwarves are extremely well suited to living in the desert as is. Much better than humans certainly. [Answer] Stocky creatures can adapt to a desert, they'll use their stockiness to store water. So these dwarved will be weaker than regular dwarves: theit bodies will have less bone and muscle fiber, and more tissues that can store water for long periods. As for the beard, theirs will somehow accumulate static charge. The hairs will repel each other, exposing more hair to the surface. ![Desert Dwarf beard](https://i.stack.imgur.com/CYNMA.jpg) (I just googled for "zapped beard") This way their beards actually become excellent for heat dispersal! [Answer] I think there could be at least three different scenarios for 'desert dwarves'. First, if the dwarves were already formed as a species and had culture and tool use by the time they came to desert, I do not think they would change much. As many other answers here tell, sapient creatures do not adapt to the environment too strongly - they have tools to take the edge off the environmental pressure. Most what would change is the skin and hair color and eye shape. The second scenario is a scientific 'common ancestor' approach - evolution in your world works pretty much the same as in ours, without magical interference. 'Dwarves' are sapient humanoids evolved from the desert-dwelling burrowing primates. I do not think they would retain all the adaptations of their burrowing ancestors - those were much more adapted to desert. I would say, they would be something like humans, if humans evolved from desert nocturnal stalking omnivores instead of savannah endurance omnivores. Shorter, with more strength and less endurance, possibly big ears, broad and soft feet, and more body fat. I do not know about beards - I'm not up to date on the evolution of human facial hair. Such creatures would since then spread out from their ancestral deserts and live in other environments too. The third scenario is 'intelligent design' - some magical or scientific power had consciously worked on adapting human or dwarven baseline stock to desert. That power would most likely go overboard and try to create an ideal 'desert-dweller', cramming as many features from different desert animals as possible - here you can just let your imagination run wild. Just take all adaptations from the list here - <http://mentalfloss.com/article/57204/20-amazing-animal-adaptations-living-desert>. They would have very variable metabolism, being able to slow it down significantly. A lot of fat, possibly in the form of special humps. Closable nostrils and additional eye memrane like camels, different water exchange as in some dessert antelopes (say, they don't need much water and don't urinate, instead expelling uric acid as solid). These creatures would be actually overspecialized for desert, so it would be hard for them to live in other environments. [Answer] The dwarves in my fantasy setting actually specifically evolved in the desert. Their small size allowed them to burrow underground, escaping predators and gaining shelter from the sun. Their beards evolved from ordinary facial hair into something more like whiskers that help them sense their surroundings in the dark. Their stocky body plan makes them more efficient at digging with or without tools - just look at any burrowing animal (and note how many of them also evolved in deserts or other dry areas). ]
[Question] [ I use forememory instead of foresight, due to how the ability works. A cunning and creative person can remember five minutes into the future, and are smart enough to exploit it in any way possible. For simplicity, I will name the person "Abe". They are the only one with this ability, so others seeing the future and changing it won't be a problem. Recalling the previous five minutes and recalling what occurs in the next five minutes are exactly the same for this person. They could spend a few seconds remembering, then take action upon this. Why can't they abuse their power by reiteration (write a note, see his future self writing the note, repeat until two minutes foresight can be five years foresight)? Clarifications: Abe's five minutes forememory are of what will happen if he didn't remember the future. The act of remember automatically changes the future. However, since the forememory shows Abe what happens if he didn't use the ability, he can do reiteration: If Abe "remembers" nothing happens, Abe doesn't need to take action, but if he makes a warning to his past self, his past self will change their actions, because Abe changed what he did. One possible result is that as soon as Abe can use this power, Abe gets warnings of the future regardless of what he does. This is one reason why I want to "disable reiterations" (although, it would be an interesting story where a person can warn their past self, and the story is how every action they take they still regret their life and warn themselves). What is reiteration? Skip this last paragraph if you already get it and don't want my clarification of what I envision the ability to be. If you say "pencil" and wait a minute, you will have little difficulty remembering what word you said. It will also take you only a few seconds to remember this. Then, you say the word you remember to a friend. The friend won't have memory of what you originally said (like Abe can't remember 10 minutes ahead), but can remember what you just said (like Abe remembering 5 minutes ahead). This can be "reiterated" until you have a chain of any number, as Abe can do to remember into the future of any distance. In the case of Abe, he can do a similar process. Let's say nothing interesting happens to him for a few hours, but he vigilantly uses his forememory just in case during the whole time. Then, an ambush happens and he is trapped. The ambushers plan for his ability, and wait 5 minutes after blocking all escape routes before revealing themselves. Abe remembers the future out of habit, and notices future Abe getting hit from behind, just like you might feel pain in a memory. Abe quickly writes "Ambush 18:41" on his palm with a marker always kept in his pocket or nearby. Now, the story changes: Abe has nothing happen for a whole week, but vigilantly uses forememory and notices his future Abe writing down "Ambush 18:41". This is because the forememory shows what will happen if he didn't use the ability. What would happen is that he writes the warning on his palm as soon as he knows. Since Abe can see the warning 5 minutes in the past, and the warning is made 5 minutes before the event, Abe has 10 minutes preparation. If Abe writes a warning of the warning "Ambush 18:41" on his palm, the previous him gets 15 minutes of time. Reiterated, Abe could go until the moment Abe woke up that day. If Abe is willing to sacrifice sleep and only sleep 4 minutes at a time, he can sleep 4 minutes (with a loud alarm), then use a minute to check the future and write down a warning on his palm if necessary. If Abe ever fails to keep this chain working (like waking up late), Abe will notice this with the futurememory, and take action to correct it. Note: 18:41 is military time 6:41pm. If Abe desired, he could also write the date instead, or use an extra five seconds for more information if needed. [Answer] ## Future you has faulty future memory So, when you look into the future, you are not seeing the actual future. You are seeing a possible future (since seeing the actual future would cause all sorts of paradoxes). The world in this possible future has some differences. One of them is that your future memory is faulty in this non-existent world. In particular, if the you in your future vision tries to use their own future vision past what your own future vision could look, they will get a false reading. It will be plausible, but false. This means that if you try to pass a note back by more than two minutes, the note will get horribly corrupted, even if its just 5 minutes and 1 second. Alternatively, you could say that the you in the future memory has future memory as accurate as your own, but "recursing" causes cumulative errors. You can explain this in analogy to mirrors: [![](https://upload.wikimedia.org/wikipedia/commons/4/40/Infinity_Mirror_Effect.jpg)](https://commons.wikimedia.org/wiki/File:Infinity_Mirror_Effect.jpg) Notice how as you get deeper, the mirrors get darker. Likewise, trying to pass a note back 5 years would make it completely garbled. Even if the note is not garbled, the information it contains will reflect a horribly inaccurate future. You could try to recurse, say 15 minutes or more and probably be fine, but it wouldn't be as accurate as five minutes. [Answer] If you do this, you are committing to writing and reading a note every two minutes for the next five years. Even if it's not the same you, because you branched from that timeline by seeing or acting on this information, for this to succeed, there must be some potential chain of custody where you stayed awake for five years straight writing and reading notes to get this information back to yourself. I shudder to think of the kind of future that you're trying to avoid that would make that level of effort worthwhile, and marvel at the dedication and willpower that would be required to successfully push the note that far back. [Answer] You appear to have answered your own question: > > The future changes only if the person attempts to recall their "future-memory", regardless of whether an action is taken based on the new information (for example, unconscious hesitation messing up the events slightly). > > > The act of foresight itself changes the future - and continually looking forward instead of taking action continually invalidates the previously anticipated future. There may be a hard natural limit to how much of the future can be foreseen - somewhat like thermodynamics limiting absolute possible efficiency of a process (at well under perfect efficiency). Like PyRulez suggests, everything beyond some limit becomes indecipherably fuzzy. Or, alternatively, your seer might actually be seeing all possibilities - and the limit might be the power of the mind of that person. For ten seconds, you might be able to comprehend all the possible futures. To look forward two minutes, you're really just estimating. For ten minutes, no mind could hold that many possibilities. And to look forward at every possible future in the next hour would require more mental processing power than is possessed by the entire human family. [Answer] Context. The actual information content of your future sight is pretty minimal. Instead of seeing everything that's going to happen, like a time-traveling video stream, you get glimpses of important facts. Your brain then slots those facts into the context it already has, making a coherent narrative out of them. You "remember" a sharp pain in the leg, you see a man with a gun, your brain assumes that means he's going to shoot you in the leg and you dodge. Because the timescale is so short, usually the context hasn't changed very drastically and the impulses and impressions you get from the future make intuitive sense. (Incidentally, the name "future memory" for this sort of foresight is very accurate, because it's analogous to how normal memory works. We don't remember things as hard data: we remember impressions and associations, and when we need to recall directly, our brain reassembles the context on the fly. This leads to a number of well-known tricks and faults in recollection, like conflation of different events or even outright invention of things that never happened.) However, this means that your ability to capture discrete, written information from the future is pretty limited. You might be able to grab a few snippets, like what number someone's about to pull from the lottery bin, but a whole composed message would be beyond you. You would spot a few details and have to fill in the gaps - but because it's present-you that's filling in the details, not future-you, you don't necessarily know how to interpret what you're remembering. The more you do this in a row, the more pronounced these errors become, until you're mostly working off of your present knowledge and ability to make guesses about your future state. That's a handy skill, but it's intuition, not precognition. [Answer] * If it is future memory, then it is only about what you will know in future, that itself limit what information can you try to send back (just what you discovered personally). * Also as you can see just two minutes ahead, you have only two minutes to read and write the full message (and errors are propagating with it - once you make mistake in number that digit is lost/mangled forever) * You cannot sleep all the time, or the line is broken and lost * More over I would put a small penalty on using that ability - not big, but cumulative (makes you more tired, like pushing heavy weight or solving hard logical example) - so it is not a problem use it occasionally for two or three minutes, but for ten minutes it accumulate to serious tire and for an hour it can knock you down temporary. + Using it two minutes, rest five minutes and you are ok as if you just sit idly all the seven minutes (still you want to go sleep after like 16 hours) - after all it is extraordinary mental task to use future memory and interpret it right. + So there is a physical limit to number of iteration, until you are forced to stop (and as author you can set that limit as high or low as you see fit, maybe little longer for extra important messages - more effort done) * As was mentioned, it is "just" memory, so anything more complicated get interpreted and be retold each time (Chinese whispers), so each iteration is more garbled anyway. In my experience five steps nearly assure even simple sentence to go wrong (that is 10 minutes max). [Answer] The “cool-down period” seems like a sufficient solution. If I can’t use the ability for `x` minutes after the last time I used it, then when I observe myself 2 minutes in the future, that version of me cannot also be looking at the future, since he/I used the ability 2 minutes in his past. For this to make sense, the ability would need to be a one-shot thing; when you “fire” it, you remember everything that will happen in the next two minutes, but you have to wait at least two minutes before “firing” again. If for some reason you don’t want to use that restriction, there is still the “butterfly effect” argument: the further back in time you send a piece of information, the greater the chance that you change history so it never ends up being true after all. However, this doesn’t apply equally to everything – if you see the Earth being hit by an asteroid in 3 years, it is highly unlikely that your reaction will inadvertently change that outcome. Also, as noted in other answers, each iteration introduces potential errors – if you write something down from memory 5,000 times, it’s unlikely you will get it exactly right each time (though again, “asteroid strike June 7 2022” is hard to get wrong). And sleeping for more than two minutes will break the chain, which rules out recursively seeing more than a few days into the future (unless the memory is shocking enough to wake you). A completely different, but arguably more self-contained approach would be this: 1. The ability works continuously – your memory simply starts 20 seconds ahead of the present 2. Recursion is possible – you premember premembering stuff that happens 20 seconds after 20 seconds from now, and so on. But you just can’t process more than 5 or 6 levels of recursion, so in effect, you can’t resolve more than 2 minutes into the future. This would vary depending on the complexity and intensity of the future stimulus; you might foresee being electrocuted 5 minutes in the future, because it would grab your future attention so strongly. 3. Writing stuff down (or equivalent) is not a workaround, because if you write something down now, you won’t decide to write it down 20 seconds from now, so you won’t premember doing that in the first place. In other words, it creates a paradox to physically react to something beyond the current horizon of your memory. [Answer] *Consider things from the perspective of the you who writes* the note instead of the one who reads it.** If something bad just happened, and you can write a note telling your past self to do something different, then you rewrite the last couple minutes of your life with a (hopefully) better version. That doesn't seem like a bad deal; it's basically the same as trying something again, and then forgetting the first time you tried. You forget more than that every day. But if you want to send a note back five years, you will necessarily be erasing the last five years of your life. Are you precisely the same person now that you were five years ago? If not, are you willing to effectively end your life so things will go better for past-you? Even if your personality hasn't changed much in that time, any message going that far back is likely to change a lot. Do you tell yourself to get a different job? Even if it's in the same city, your schedule will change enough that you'll interact with different people, on and off the job. Hopefully you don't especially like any friends you've met since then. In turn, most of the conversations you had in the last five years never happen. Is there anything you learned, either in the conversations themselves, or by reading up on something that was mentioned? That knowledge is now gone. Have you created anything in that time? It may never be made. For that matter, have you had children in that time? You may have children in the new timeline, but absolutely not the same ones. And all of these consequences potentially apply (to a lesser extent in most cases) to anyone you interacted with over the last five years. Even if long-term use of this ability is easy to accomplish, it is not a decision that will be made on any sort of regular basis, and it is a severe sacrifice even if it's deemed worth it. Of course, there's a period of time between the two extremes. Some quick googling suggests that you can buy lottery tickets as little as 15 minutes before the winning numbers are drawn. All I've done in the last 15 minutes is write this answer, and I'd be willing to lose that for a few hundred million. So if you're reading this, it means I was unable to send that message. [Answer] The very act of looking at the future changes the future which prevent iteration You can look at the future, as it is at the time of you looking, but by looking, you choose the best path which means the future you just looked at is no longer the future you saw. If the future has changed because you looked, trying to iterate to see more fails. [Answer] A way to solve for this is to make the memory/visions of the future come in not 100% clarity. Think of how in the movie Pitch Black how Riddick sees the world. It is semi garbled. (does not have to be uni color, but does help in the obfuscation) . But by having the information not 100% clear there is active thought needed to clarify and understand. Text is difficult to read if not of billboard size. [![enter image description here](https://i.stack.imgur.com/Zm0z7.png)](https://i.stack.imgur.com/Zm0z7.png) This simple implementation would be enough to not allow exploitation into 5 years of the future while still keeping the ability highly useful. (again refuring back to that Sci Fi movie where a little foresight lets him fight effectively the final necromonger boss.) Short sweet simple solution is the best! [Answer] Time blurs. There's not a hard cut-off after two minutes, that's just an approximation. Instead, quantum uncertainty effects stack up to make future 'memory' more and more uncertain as you look farther forward in time - meaning that anything farther ahead than (approximately) two minutes is very unclear and unreliable. Writing a note doesn't help this, because two minutes in the future there are multiple possible versions of you writing slightly differing notes, and the further ahead you try to look the worse it gets. Try to look ten minutes ahead, and there are billions of possibilities and no way to distinguish between them - useless. [Answer] Because future you wouldn't care about past you. Imagine something terrible happened to you (#1) a minute ago. You (#1) write out a note to warn an earlier version of you (#2). You (#2) write a note for the next one (#3) and make whatever change you (#2) hope works to prevent terrible thing from happening. You (#1) still live with it having happened. You (#2) might fix it, but also get no benefit from writing the note for the next guy (#3). The only benefit is for someone else. So, why would any of you write the note, especially when you are still grieving (#1), or preparing to prevent tragedy (#2+)? Also, were you looking at the future, two minutes ago? Otherwise no one would be there to read the note. It's funny you mention Next, because it's loosely based off a Philip K Dick short story, The Golden Man. That guy spends most of his life, just sitting around, ignoring the present, while he looks at the future. He's not exactly well adjusted. [Answer] Every time you look into the future, you instantly change something about that future. If you focus on trying to remember something, you spend time in doing so. If you sped three seconds remembering a specific event, that results in you not spending three seconds doing the thing that led up to that specific event. It's really impossible to remember anything vividly without focusing on it, which means you cannot multitask and have the same degree of memory or detail of memory. You HAVE to stop for some period of time to think about the future, which over iterations will build up to minutes and hours, which will in turn massively change your current future with the butterfly effect. Think about it in context- your person will never know when he will have a chance to remember his message from the future. He has to spend ALL of his time trying to remember the future, which would be an enormous waste of time and potential. If he misses the message from five minutes in the future, that means he has lost the original message for good. Imagine it like this: #1 is the person sending the original message, far in the future. Now, you are person #1200, and 5 minutes in the future you are person #1199. If you look into the future as #1200, you will have changed the future, possibly even causing #1999 to miss the chance to look into the future, breaking the chain. However, if #1200 does NOT look into the future, the future will not change, and the everything will be exactly the same as person #1 since it will be impossible to receive the message of any person in between. This means you have to be available in those five minutes when you can receive the message, which kind of reiterates what you said in creating the chain in the first place. Now, this answer is different from others in the subtle difference between chance and actuality. True, in the timeline the message is intended for you only have to look into the future once in order to receive the message. However, as the person of that timeline has never received the message before, he has no tangible or immediate reason to look into the future, almost certainly missing his chance. In this scenario, the person would be lucky to have a long-term message manifest once in his life. Another possible scenario could be the pre-determination of a system, such as yours, in which a person is available and has the intention to receive a message at any time. This would require waiting for YEARS, doing nothing else but waiting for a glimpse at the future. This sort of inactivity would most certainly screw up his future, changing everything and making the information irrelevant. Finally, even if you set up a system in which the intended recipient of the message sends it back even further in order to make up for the time each timeline has spent waiting, there is still one glaring issue with the concept of time-traveling messages: You can't do anything about them. I mean, the moment you do a single thing different from person #1, you have lost that future forever. Unless future you is omniscient, there is absolutely no way you could figure out exactly what to do so that you could arrive in exactly the same future with only one thing being different. There is honestly no way I could explore all of the possibilities of your future memory without brutally strict definitions about time and perception, which is something humans will probably never understand. I'm not even going to get into the different types of timelines and theories of existence people have created, from alternate universes to one continuous universe in which characters must disappear from one time in order to appear in another. My response covers only one of these theories of time, in which time travel instantly creates an alternate timeline and universe. If you want a more brief explanation of each type of timeline, I would recommend you watch the short video down below. It gives good examples of each form of time travel as well as the implications of each. [10 Minute Youtube Video](https://www.youtube.com/watch?v=d3zTfXvYZ9s) [Answer] Think back to the game telephone where each person stands in a line, the first person is told a phrase, then they tell it to the next person, and so on. The final person in the line says it for everyone to hear, and is almost always very wrong. It may be like that, where each iteration might accidentally read the note wrong, or have bad handwriting. So it could go from ‘meet Molly at 3:50 at McDonald’s’ to ‘meet molly at 3’. This is confusing because he doesn’t know where to go. These mistakes would also likely happen if he is tired or just woke up, meaning they could be even more garbled/incorrect. For lottery numbers, it could go from ‘34883’ to ‘34852’ as they may white down the wrong number because of them not having good enough memory to copy a long number without looking back at it, which could break the chain if they take too long. ]
[Question] [ Ideally, when I die I want to be blown up; go out with a bang, you know? However, I wouldn't want chunks raining down on everyone. How much TNT would I need to have secured for my funeral to completely destroy my body? [Answer] We have discussed [how much energy it takes to vaporize a person before](https://worldbuilding.stackexchange.com/q/108339/21222). It is within the vicinity of three gigajoules. Using [this handy conversion table](https://en.wikipedia.org/wiki/TNT_equivalent#Historical_derivation_of_the_value), we can see that a little less than a ton of TNT would do. However, that is a VERY BAD IDEA™. [In 1970, some people decided to blow up a whale using half a ton of TNT](https://www.youtube.com/watch?v=GkZottYDpEE). Granted, that is less than my quote for little less than a whole ton above, and whales are much larger than humans[citation needed]. However, the effect would be similar to what you can see in the link... A blast of TNT does not release all of its energy as heat, and even if it did, the application on your body would probably not be optimal. Little bits would be flying everywhere anyway. [Answer] Quoted from [Slashdot](https://science.slashdot.org/story/13/09/13/2122208/it-takes-299-gigajoules-to-vaporize-a-human-body), sources provided on the page; > > First, consider the true vaporization [the complete separation of all atoms within a molecule] of water. With a simple molecular structure containing an oxygen atom bonded to two hydrogen atoms, it takes serious energy to break these bonds. In fact, it takes 460 kilojoules of energy to break just one mole of oxygen-hydrogen bonds — around the same energy that a 2,000-pound car going 70 miles per hour on the highway has in potential. And that's just 18 grams of water! > > > So as you can see, it would take a gargantuan amount of energy to separate all the atoms in even a small glass of water — especially if that glass of water is your analog for a person. The human body is a bit more complicated than a glass of water, but it still vaporizes like one. And thanks to our spies spread across scientific organizations, we now have the energy required to turn a human into an atomic soup, to break all the atomic bonds in a body. According to the captured study, it takes around three gigajoules to entirely vaporize a person — enough to completely melt 5,000 pounds of steel or simulate a lightning bolt. > > > This is obviously a lot, but how much TNT does this translate to? A metric ton of TNT contains [4.184 gigajoules](https://en.wikipedia.org/wiki/TNT_equivalent) of force, so we actually have some left over from removing your meaty bits. But the crater will be so big that you should probably just use a different method. [Answer] I'll just give you a factual reference: August 2 1980, a terrorist group set a bomb in the waiting room of Bologna station: 5 kg of TNT and T4 plus 18 kg of nitroglycerine. Of the 85 victims, one body was never found: it is believed that person was right next to the bomb when it exploded ([source](https://it.wikipedia.org/wiki/Strage_di_Bologna)). [Answer] Have you considered thermite? Thermite mixes produce vast amounts of heat when ignited instead of exploding. So perhaps the body could be packed in thousands of pounds or kilos, however much it is calculated to take, totally surrounded by thermite, and placed on a flotation device on a body of water hundreds of feet or meters, however far the safe distance is calculated to be, from land, and ignited. [Answer] According to Slashdot (Apparently they are still around), it takes [3 Gigajoules to completely vaporize a body](https://science.slashdot.org/story/13/09/13/2122208/it-takes-299-gigajoules-to-vaporize-a-human-body). According to [online conversion calculators](http://www.kylesconverter.com/energy,-work,-and-heat/gigajoules-to-tons-of-tnt), it takes .72 tons of tnt to get 3 gigajoules. As Renan pointed out, that's not great because the blast goes in all directions. But there are a few possibilities; 1. A human is considerably smaller than a whale (for most humans and most whales). Definitely smaller than the sperm whale in the video. 2. The video only used half a ton, not the almost three fourths of a ton that you'd need. 3. We can improve things using [shaped charges](https://en.wikipedia.org/wiki/Shaped_charge), which can be highly directional. Instead of having the explosion go in all directions, send the blast straight up through the body. This will minimize the crater and ensure more complete destruction of the body. [Answer] If the pulse detonation wave is particularly powerful a few pounds of composition explosive will scatter the body into unrecognizable pieces. But vaporization.......requires bare minimum of incineration so an incendiary explosive is in order. Several kilograms of high explosives ]
[Question] [ I want to start writing alternate history story, set in the 'Wild West' where there are factions of Muslims and non-Muslims vying for territory and resources. I need to have a reality check on this concept before I start laying the foundations of world building. Essentially I want to fill the gaps in my knowledge, by finding the fewest questions I need to answer to reasonably explain this alternate history. (n.b. I don't want you to answer these questions, I want you to ask me questions) Here are my requirements: * Reality splits after Muhammad's (ﷺ) death in 632 * Muslims retain a foothold in Spain and a large amount of Europe * Large-scale colonization of America by both factions (with in-fighting being expected, and not counter to this requirement). * Norsemen are still recognizably in existence, and not converted to Christianity. What holes are left for me to fill in? For what it's worth, as much as this is might influence the gaps to fill, there are an elite few in this alternate reality who can either use Djinn to 'mind-control' individual people (Muslims) or turn individual people into large troll-like creatures (Norsemen) I can think of a few 'turning points' I need to answer, however they'd be better broken down to smaller more precise questions: * How does Muslim Spain prevent itself from being re-taken? * How do Norsemen gain control of Britain in 1066 (which may be considered the [end of the 'Viking Era'](http://www.hurstwic.org/history/articles/society/text/what_happened.htm)) * What drives the above factions to go to America? What other questions do I need to answer, for a believable alternate-history? [Answer] # How do the Vikings not become Christian? Even as the Vikings were militarily successful, they were falling under the cultural sway of the geo-politically weak Christian nations. Clearly, there was something powerfully attractive about Christianity. In order for your Vikings to stay noticeably Viking, and not generically Northern European, they have to keep their own religion, possibly developing it into something that can compete with the proselytizing success of Christianity and Islam. # Why does this Viking/Muslim Europe advance so fast? This is a tricky one, since it is not entirely clear what made Early Modern Europe develop so fast. It is undeniable that a region that was probably the least developed of the four major cvilization centers of the Old World (out of China, India, the Middle East, and Europe) in 1400 ended up clearly ahead as soon as 1600 and far ahead by 1800. But what caused this is up for debate. Suggestions include: * The competition between secular and religious authority and the legacy of feudalism lead to stronger property rights in Europe than elsewhere. * The legacy of Republican Rome and the tension between independent secular and religious authorities undermined the absolute nature of monarchy. For example, only Europe had a situation where a powerful King (of France or Spain) nominally owed religious obedience to a religious leader outside his own authority. * A large number of relatively stable states limited tyrannical governments' ability to stifling trade and development. * A large number of states lead to increased competition and warfare, and fast development of weapons technologies. None of these reasons seeems fully satisfactory, so a combination of them is probably more accurate. In any case, if your Viking-Muslim continent gets together, how do you reasonably replicate the fast growth and technological development (both in shipbuilding and weapons) that allowed Europeans to go to other continents and push the natives around? # What drives New World Colonization? There were three major factors for early colonization efforts in the New World: gold, sugar and religious persecution. The Spanish got into the game first with the gold. By 1535, they conquered both Mexico and Peru and their corresponding gold reserves. Most of the first Europeans to permanently settle the New World did so in relation to one of these two territories, either in their capitals (Mexico City and Lima grew large) at the mines (Potosi in Bolivia grew to almost 100,000 in this time period) or in ports servicing trade to these places (Veracruz, Darien/Panama, Havana, Acapulco). The second big pull was sugar. There wasn't much good land to grow the stuff in the Mediterranean, and most of that land was in Muslim hands anyways. Already colonized places like Havana and Veracruz were perfect for this crop, as was much of Portuguese Brazil. Once the slaves part of the equation came in to play, this became the perfect high risk/high reward venture for adventurous European lesser nobility. Spend thousands on slaves, hope you don't die of malaria; if you can ship a few tons of sugar back to Europe each year, you will be rich. The last pull was religious persecution. The Pilgrims of Massachussets and the English Catholics of Maryland are two examples, as were abortive Huguenot colonies in Brazil and Florida and other places. These colonies were the most stable in the long run, since they were by families who intended to stay put, not greedy pillagers and slavers. By the 1700s, the victims of religious wars in Europe were filling the New World: oppressed Scots-Irish; the rest of the Huguenots; German Catholics in Protestant states and Protestants from Catholic states, etc. In your world, how do you provide the same impetus driving people to plunder, enslave, and/or settle the New World? [Answer] > > How does Muslim Spain prevent itself from being re-taken? > > > The turning point of the Reconquista, the war of the Christians against the Muslims of Spain was the year 1000 AD. The Caliphate of Cordoba suffered of internal conflict, civil war and political fights for the power, with a 10-year-old caliph. If you keep the Caliphate stable, without hiring Christians to fight wars for them against their enemies and those Christians can't breed so many horses as they did (in the wars of 1200 the proportion of mounted soldiers in the Christian army was at least 40%), it is reasonable they stay in power. > > What drives the above factions to go to America? > > > For the Muslims, somehow they get interested in the Fortunate Islands as the Romans called them (the Canary Islands). Once conquered the guanches (the people of the Canary Islands), an easy feat because those guanches are a Neolithical society, they could discover a Phoenician route to the Azores. Once in the Azores, a lost ship could end in America and return with just a lot of luck. The Muslim ship gets back with slaves and gold and it is all Al-Andalus needs to be interested in conquest. [Answer] I do not think there are that many issues at the general level. You'll need to drill down to details to get real issues. The issue with Muslims was infighting. You just need a stable Muslim state to rule the western Mediterranean. They'd be richer and more advanced than their Christian competition so they'd probably have no issue defending themselves. More likely they'd expand to Southern France and parts of Italy. I guess you'd want to pick some suitable Muslim state to promote, find out why it failed, and how to prevent that failure. For the Vikings, the issue was lack of cohesion. They came to the South, adopted local religion and culture and more or less merged with the Christian culture. Since you want them not to be Christian that might be your best bet. If the Norse stay strongly pagan they'd have a strong cultural identity of their own and not merge with the Christian Europe. For that you are going to need a religious reform. The Vikings will need to adopt more organized religion with upgraded theology. Simplest explanation is that they'll do so in response to Christianity and Islam by adopting and incorporating elements of those religions to their own religious practices. Hinduism successfully underwent something like this in response to competition from Buddhism and Islam. You can use that as a reference. Another possible reference is the trilogy starting with "The Hammer and the Cross" written by Harry Harrison and John Holm (pseudonym) that basically is about Vikings resisting Christianity. The questions would be about reforming Norse paganism to something competitive with Christianity. Having them colonize the Americas would be fairly simple. As everybody knows the Vikings did actually settle Greenland and a short lived colony in Canada(?). A strong Viking kingdom would have followed up on that almost certainly at some point. And when they did the Muslims would have heard about it and sent somebody to investigate. Not sure if there is anything to ask about that part. [Answer] How does Muslim Spain prevent itself from being re-taken? By avoiding the fracturing that happened when the Ummayads were toppled. That weakened the muslims in Spain so much that they never recovered and got defeated by small christian kingdoms. Unified, solid, muslim empires are tough nuts to crack, just look at the Ottomans or the Mamluks of Egypt. How do Norsement gain control of Britain in 1066 (which may be considered the end of the 'Viking Era')? By abandoning the tribal customs establishing norman feudalism generations earlier. A norse high king will have to emerge, using, somehow, the norse religion to justify a feudal monarchy, the development of a monarchy and the development of an improved norse metaphysics will have to walk side by side. But the norse lacked philosophy to systematize their religion like the egyptians and the chinese did. They will have to borrow the philosophy from somewhere and, if you want to keep them pagans, that means neoplatonism (they are too far away from China or India to be inspired by taoism or hinduism) and in 1066 that means that they will have to sack Constantinople or Egypt to get the late-roman manuscripts. What drives the above factions to go to America? In our timeline, the discovery of America was inevitable because the fishing boats hunting cods and whales went deeper and deeper into the Atlantic. Eventually they would get on the other side and the stories about a big land full of resources would spread. Eventually they would start planting sugarcane and tobacco in Cuba and Haiti, get very rich in the process and the rush for the new continent would begin. Both the norse and the muslims would them fill America with slaves, driving settlements in african coast in the case of muslims and raids in Europe in the case of norses. What other questions do I need to answer, for a believable alternate-history? How will the norse paganism interact with the natives, specially in Peru and Mexico? the aftermath of a norse conquest of the aztec empire will be quite different because instead of supplanting the aztec religion, the norses will merge the religions (like the romans did in Egypt and Syria). How will the muslims react if a native nation convert en masse to islam like the volga bulgars did? Will the muslims burn the american wealth in religious wars like Spain did? Maybe Spain will be Shia and will burn itself attacking the sunnis in Anatolia or Egypt? Also: norse slave trade, enslaving christians to man the tobacco and sugar plantations will devastate christedom in the same way that the old nigerian kingdoms were devastated in our timeline. [Answer] Partial answer, since the rest is fairly well covered already: * Norsemen are still recognizably in existence, and not converted to christianity Actually... This one is VERY easy to explain. If the norsemen can turn people into large, troll-like creatures, and that was somehow tied into the norse religion? That'd be a pretty strong counter to any christian influence (who stopped being able to present miracles shortly after the death of christ even if the bible is 100% real in this world). I'd worship odin and sons over jesus any day if odin's priests can show me the might of their god(s) and the christian ones can not! [Answer] Given the nature of most of the colonists in North America, I have a pair of questions for you: * What were the Muslim running from? * Who were the Muslim authorities trying to get rid of? There are plenty of ways and reasons to exploit a new land but the first few rounds of that exploitation are usually pretty rough. It seems to me that desperation or coercion were factors in early historical colonization. The answer you choose to either of those questions will have a profound effect on the resulting story. [Answer] Christian Monks are Martial Artists When the Vikings raided Lindasfarne Monastery in 793, they were shocked to find that the humble men in burlap sacks and silly hair cuts were more than a match for them. Fighting with heavy bronze staves, they smashed the raiders to pulp. After the fighting, they patched up the raiders, taking care of them while they mended bones. After several months recovering, they sailed back home. "Don't f\ck with those Britons, they are some crazy bastards!" They told their friends. One of their friends said that he heard that his cousin's lord's uncle's brother-in-law found this land further west. It's a much longer sail, but there's no crazy warrior monks waiting to bash your skull in, then patch it up. Britain is, after all, a silly place. Muslim armies liked to fight with champions. Sometimes, they would have a 1v1 and respect the results. When they invaded Spain, the Spaniards sent out their champion. A man with no armor, armed with just a staff. "1v1 me", he said. The Generals picked their champion and sent him out. This funny looking peasant with a staff beat their champion like a rented mule. Could every* Spanish peasant fight like that? "Best not to find out, let's go back to Morocco". They agreed. With the war avoided, the Caliphate developed strong ties with Spain through trade. The silk road got on boats in Jerusalem and sailed to Gibraltar. An enterprising Moroccan merchant decided that it was taking too long to get the silk from China. Maybe it would be faster to go the other way around the world. He sets off to find China, but finds America instead. ]
[Question] [ Given the existence of neon kittens with: * the internal properties and mentality of normal kittens * bioluminescent fur. What evolutionary process outside of intentional human breeding/gene manipulation would lead to cats with glowing skin or glowing fur? If bioluminescence can't be achieved then florescence under UV light would work. The environment is normal Earth. [![Neon Kittens](https://i.stack.imgur.com/wmKcO.jpg)](https://i.stack.imgur.com/wmKcO.jpg) [Answer] [![glowing cat](https://i.stack.imgur.com/pVz55.jpg)](https://i.stack.imgur.com/pVz55.jpg) The cat above glows [because it was exposed to a virus that carried a suitable gene](https://www.theguardian.com/science/2011/sep/11/genetically-modified-glowing-cats): > > US researcher Eric Poeschla has produced three glowing GM cats by using a virus to carry a gene, called green fluorescent protein (GFP), into the eggs from which the animals eventually grew. [...] > > > The GFP gene, which has its origins in jellyfish, expresses proteins that fluoresce when illuminated with certain frequencies of light. ([citation](http://dx.doi.org/10.1038/nmeth.1703)) > > > Now that was about intentional human action, genetic modification, which is not what you asked about. But what I noticed in that article is that the modification to the egg is virus-borne. Ok, could that happen without human intervention? [This article from a veterinary site](http://www.exoticpetvet.net/avian/eggs.html) talks about diseases that can be transmitted to eggs (and the resulting young) in birds. Birds are not cats, but let's see what they have to say about vectors: > > There are many infectious organisms that can be transferred from the hen to the egg that may cause the egg to die. In some cases, the infectious organism may infect the egg, yet the embryo may continue developing, and may even hatch, carrying the organism at hatch time. If an organism is passed from an infected hen directly into an egg, and then into the developing embryo, this is called vertical transmission. > > > We know that something similar happens in mammals; a mother who is infected, or drug-addicted, can transmit that condition to her fetus. So, what we need is a way for a jellyfish-borne virus to affect a pregnant cat. [![cat on beach](https://i.stack.imgur.com/QuVpr.jpg)](https://i.stack.imgur.com/QuVpr.jpg) ([image source](http://www.123rf.com/photo_21491775_breakfast-cat-with-fish-in-mouth.html)) Fortunately, cats love fish, and fish are found on beaches, where jellyfish are also found. An infection through that vector to enough cats over time, and with the affected gene being transmitted to those cats' young and so on, could give you occasional glowing cats. [Answer] Cat fur is lovely, yes? That think the bacteria too! A long long time ago, some [bioluminescent bacteria](https://en.wikipedia.org/wiki/Bioluminescent_bacteria) got into the fur of a cat. That made the cat look amazing! The lucky cat got admiration from its peer group, and therefore had a higher chance to reproduce. That happened multiple times, causing the share of the cat population with a fur that was a good place to live for the bioluminescent bacteria. Enjoying such a mutual benefit, the bacteria is now always found in every cat colony, resulting in wonderful glowing cats at night. Bioluminicent bacteria: [![bioluminicent bacteria](https://i.stack.imgur.com/tOqr8m.jpg)](https://i.stack.imgur.com/tOqr8m.jpg) (image from [here](https://blogs.uwe.ac.uk/teams/hls-research/Lists/Photos/Research%20image%20of%20month/bacteria.jpg)) [Answer] [Cat pee glows under a black light](http://chemistry.about.com/od/weirdscience/fl/Why-Does-Urine-Glow-Under-a-Black-Light.htm). Cats on this world use their pee as a defense mechanism against other cats, and are constantly spraying each other. They also have evolved very porous fur. The Phosphorus from the pee absorbs into the fur, causing it to fluoresce under a UV light source even after the cat has cleaned itself. [Answer] It's a combined mating display and defense/camouflage mechanism. Lets say the cats can go one better than just glowing all the time and actually have some control over it. This could be achieved by having both glowing and non-glowing fur and extending or retracting one type by preference to the other. This gives them control over their glow. The mating display aspect is obvious. The displays are used to lure and impress mates. For defense when startled or threatened the cat would immediately start to glow, with the glows being patterned to suggest larger size and emphasize claws and teeth etc. This would allow them to scare off other predators and help claim territory. For camouflage during the day the glowing fur and normal fur can be used in a similar way to stripes to break up the shape of the cat and help it blend into the environment or at least not look like a cat. This would be done by only revealing some glowing fur at a time and doing so in odd patterns. ]
[Question] [ Let's say you had a world much like Tolkien's Middle Earth. Elves, dwarves, orcs, and the like. Now let's say that against all odds, evil sorcerers, heroic blunders, and such that that world managed to achieve a level of technology and civilization equivalent to our own. How would Elves, specifically (in the interest of keeping the question narrow), adapt to modern society? Assumptions: * Elves. The "[Platonic](http://en.wikipedia.org/wiki/Platonic_realism)", "archetypical", or "ideal" Elves. What comes to mind immediately when you think of Elves? These are those Elves. * Elves make up a mere 5% of the global population, while humans make up 85%. (The remaining 10% encompasses all other sentient races) * Elvish society is fragmented into enclaves that hold themselves separate from human society, normally in wilderness areas (see Rivendell and Lorien) * The Elves hold themselves above the affairs of "younger" races. * Magic is rare and restricted to extra-planar beings (see Istari in LoTR) * Tech is at or about 2014 standards * Elves are vaguely respected by humans but otherwise ignored, due to few humans ever having cause to interact with them Given these assumptions (many of which, thanks to Mr Tolkien, are common to most elves in fiction), would they withdraw from technology? Embrace it? A mixture of both? [Answer] There's actually two questions here: one is a big-picture view, about how Elves would "adapt to modern society", the second is more specific: "would they withdraw from technology?" I will mostly explore the first question, because (1) it matches the title and (2) the second question (technology adoption) can only be answered as it relates to the larger context of the first (socioeconomic adaption). So: How will a proud and long-lived, but small and fragmented, minority group of Elves adapt to modern (mostly human) culture? To answer this question, one really needs to take a historical perspective. Unless the Elves were suddenly scooped up from Old "Middle Earth", and suddenly dropped off into Modern "Middle Earth", they will not be adapting to "modern" society all at once. They will, instead, be constantly re-adapting to a society that is changing faster (or at least differently) than they are. This adaptation will be an on-going process, and will also be a two-way street. As Elves are adapting to a changing society, that changing society is adapting to their adaptations. So an important corollary question is, how does human society (throughout history) react to Elves. Because then you can ask how the Elves adpat to this reaction, and what the counter-reaction to that is. Sidenote: Since I've written this, you've added a stipulation that humans generally respect the Elves, and largely don't come into contact with them. I think that at a modern tech-level, with satellites and global transportation and communication networks, the later will be relatively difficult to justify. Especially if they comprise as much as 5% of the world's population (roughly equivalent to [the entire U.S. population](http://en.wikipedia.org/wiki/List_of_countries_by_population#Countries)). It's true that there are still [uncontacted people groups](http://en.wikipedia.org/wiki/Uncontacted_peoples) in the world today, but these are rapidly disappearing, and all are extremely tiny (on the order of a few hundred people) and incredibly remote (mostly in South America, South East Asia, and Papua New Guinea). While some people believe we should let them be, others (such as missionaries, anthropologists, business developers, or tourist guides) will seek out these people. As for the idea that humans will generally respect the (largely unknown) Elves, I think this is difficult to justify from a historical perspective. One has only to look at real-life history to see analogues for how minority groups who retain a unique cultural identity are treated. Sadly, it is rarely positive, and is often filled with suspicion, fear, and even outright violence. As a disclaimer: I hope I don't inadvertently offend anyone with this post; these can be sensitive topics, and I'm painting with an overly-broad brush, and without expert knowledge on the topic. Given your parameters, it seems inevitable that, at least at some point in history, there will have been an "us vs. them" mentality between Men and Elves (this is even present to an extent in Tolkien). It's quite probably that at least some Men would even view Elves as less-than-human (and almost certain that many Elves view Men similarly). That may still be prevalent in your present, or folks may be trying to move past that. But cultural and racial grudges seem to last a very long time -- easily multiple centuries, even with our puny human lifespans (look at the Middle East conflict). With longer Elven lifespans, these grudges will probably be longer-lived. However, it's also important to remember that an individual's decisions are not bound by their race, nationality, or culture. That is while a majority of Elves (or Men) may act in a certain way towards the other, there will, of course, always be exceptions (to suggest otherwise could be construed as being racist!). Assuming your Elves want to stay withdrawn, it may not actually be their choice. At some point, the pride of Men will probably drive them to seek physical resources that the Elves have -- timber, ranching lands, oil reserves... If the two are on roughly equal terms, they may be able to trade (as between Mirkwood and Lake-Town), but if that fails, there may be war between them. However, if the sides are too vastly mismatched (because the Elves have not adopted the latest technologies as quickly, or have a substantially smaller population, or are to politically fragmented) than the weaker side may be forced to retreat. Consider the deforestation, ranching, and mining in South American rainforests, but replace the [indiginous peoples](http://www.survivalinternational.org/tribes/yanomami) being displaced with Elves. How many will choose to fight to keep the forest (possibly being labeled terrorists, radicals, or nationalists), vs. withdrawing further into it (and being called isolationists). How many will grow tired of the conflict, and move to the human cities, looking for better jobs? A similar example was the United States' expansion, and the [shameful mistreating](https://www.dosomething.org/tipsandtools/racism-against-native-americans) of Native Americans in wars and forced relocations into reservations. In Europe, we can look at the mistreatment of minority groups such as [Cagots](http://www.dailymail.co.uk/news/article-1285450/The-untouchables-FRANCE-How-swarthy-Pyrenean-race-persecuted-centuries-abused-today.html), [Romani](http://www.errc.org/article/being-a-gypsy-the-worst-social-stigma-in-romania/1385), and [Jews](http://www.ushmm.org/wlc/en/article.php?ModuleId=10005143), which, on the bad side, can range from general social stigma, to disreagard and contempt, to outright Holocaust. And then there's the question of manual labor. At some point, your society will have gone through a population boom and an Industrial Revolution. But before machinery becomes widespread, cheap manual labor may well have been an important commodity. In the real world, this led to utilizing slave labor, sometimes from indigenous people groups, and sometimes imported -- most famously in the form of African slaves. This has had widespread and long-lasting effects on the U.S., not just in terms of raical tensions, which still exist, but also in terms of cultural development. For example, in music, gospel spirituals, ragtime, jazz, blues, latin-american, hip-hop, and rap have all come to some extent from this blending of Western and African cultures. If your Elves are incapable of defending themselves, they may be similarly exploited as slave labor. But there may also be a corresponding cultural blending that occurs Interestingly, this slavery option is an approach that Dragon Age explores with its Elves, essentially placing them in urban slums, and having them be treated as sub-human.. Another question is economics. Third world nations aren't usually third world because they shun technology (even if they may have initially done so), but rather because they are stuck in poverty and can't afford all the high-tech trappings of a modern life. If your small groups of Elves are successful at remaining isolated like some South American tribes, they likely won't have the means or standard of living to afford much technology. If they become only partially integrated, as a despised subculture in slums, they might be able to afford an old TV and a used clunker of a car. If they become fully integrated into an advanced west-like society, they may well have a close-to-equal standard of living and access to technology. In other words, the level of social integration may be the largest determiner of economic means. Yet another factor to consider is that, when a group decides to stay withdrawn, a recurring theme is a generational gap. Each individual of each new generation has to make an individual choice (often during adolescence to young adulthood) to stay loyal to the "old ways", or join the "new ways". Often you hear about [tribes shrinking](http://www.ciesin.org/docs/002-268/002-268.html) as the youth move away and rejecting their parents ways, in pursuit of what is perceived to be a "better" life, or at least a better "potential" (compare this with Arwen's decision to stay with Aragorn). Granted, with longer-lived elves, this process will likely be much slower, but I see no reason it would not occur eventually. However, this can also lead to a feeling of not fitting into the new culture, or being stuck between worlds, as it were, or even looking for unique ways to integrate the old and new aspects of their culture. There is a surprising counter-example to the above, however, to be found in the [Amish](http://www.csmonitor.com/USA/Society/2012/1130/For-Amish-fastest-growing-faith-group-in-US-life-is-changing). You would expect them to be shrinking as the younger generation moves away, but that is not necessarily the case. However, many Amish communities have apparently become somewhat more tolerant of technologies (it's up to each community to decide), even while still lagging the mainstream. Furthermore, I'll speculate that for whatever reason, the Amish seem to project a certain idealized, idyllic image that allows us to see them somehow as a "wholesomely eccentric self" rather "threateningly different other". Perhaps this is a niche your Elves could fill, although I tend to think their differences would make that difficult. So when it comes to technology for the Elves, the question isn't so much "will they adopt new technologies" -- it's "will they adopt them fast enough to keep pace with human society." Because if they don't at least try to keep up, it seems likely that they would be destined to become a repressed and mistreated subculture, swallowed up within that larger society, at which point they gradually become assimilated, and eventually end up using that technology anyway. [Answer] Given that it's hard to base an answer on interracial relations, the distribution of the other races, the treatment of elves etc. since all of those can have many kinds of effects, I'm going to base my argument on the elves themselves. For the hasty, I'm going to argue that they will not* reject technology at all.* ## The "facts" From what we know of them definitively: * They live really long lives (practically immortal unless killed) * They're proud and contemptuous of the accomplishments of other races * They can't really use magic, unless they beg or ask for it I think that it's pretty clear that they would not only embrace technology, they would create new technology sometimes before humans and other races, despite the knack for it that, for example, dwarves have, or the motivation for it that humans have. Considering that, if we're going by the common portrayal here, in stories: * They use technology contemporary to the other races * They're known for great craftsmanship in some technological areas (armor, swords, bows) * They take great pride in doing this well I see no reason why they will lag behind, refuse technology or not have knowledge of it. ## Immortal engineers In fact, I think it's more likely that given their long life span, they might have some of the greatest experts in some fields - certainly not because they're cleverer, but because they have more time to learn things (and learn many disciplines well, which is an advantage) and less of their experts will die of old age, leading to having many of their accomplished engineers and scientists alive centuries after their breakthroughs. They might not really be much better than humans, dwarves or others in inventing new technology or engineering it well, but they do inherit a great amount of cultural pride, which, due to their lifespans, is unlikely to change much and doesn't really get in the way in terms of population evolution, simply because of the enormous amount of experience individuals aggregate over the course of their lives. This pride will surely get hurt if mere humans and especially dwarves (again, if elves are stereotypical) have amazing technology and they're still dependent on breastplates and swords. ## Survival Also, technology is unavoidable - without it, they won't be able to defend themselves from a point and on. Would they really trust what they see as violent humans, greedy dwarves, animalistic orcs with muskets, tanks, rockets, machine guns and nukes, without making sure they can protect themselves and fight back? While having an extra-dimensional island to escape to might not be part of every setting, even if they do have such a means of escaping danger, it won't always be available wherever they are and, since it's part of the universe, other races can and eventually will find ways to access it. Would the cautious and un-trusting elves allow themselves to be caught off guard? They might let humans fight their own wars and not intervene, but they won't let them march against their own lands uncontested. Without magic, how would they solve any of these problems? Elves often embody the "sufficiently advanced technology is indistinguishable from magic" thing in stories - swords crafted so well they can cut anything, bread made so well it fills you up after a bite, armor both flexible, comfortable, light and still stronger than any other armor. These are not always the result of magic but often the product of incredible craftsmanship. ## Why do they give such a technophobic impression though? I think this lies at the heart of how they're contrasted with humans. Elves are ancient, cautious, proud, contemptuous of younger races, believe in established and old ideals: they're portrayed no different than wise elderly people, without the "elderly" and without having to be likable. This naturally is linked, in our heads, with technophobia and the rejection of new things: because old people tend to be like that. But Elves are not old people that just have automatic plastic surgery and you can't get rid of them. They're a race, perhaps a species even, with a successful civilization and, from all the ways they're portrayed in classic fantasy fiction, a healthy technological understanding, often ahead of that of other races. If they really were technophobes, they certainly would not be known for their craftsmanship and skills. Another parallelism is perhaps to comfortable aristocracy, which I think is reflected in the dislike other races may have for elves in some settings - they see elves as incapable of understanding the threat of aging, hunger, illness etc. . This is unlikely to have an impact on technological progress I think - if this is nothing more than how they're perceived, it's not a characteristic - but if it is, comfort and lifestyle take work; if that work can be done for you, without having to depend on others, why reject it? I would like to remind that they wouldn't just get placed in modern society out of nowhere - they would live, for milennia, in a world growing and changing, with new technology arising all the time. They may be reclusive, sure - tucked away in their forests, sure. But even with that trait, I can't see them having virtually no contact with the rest of the world and certainly can't see them abstaining from technology. Because that's not how elves work and because they couldn't afford it. [Answer] I believe if Tolkien's elves were in our world today they would be very withdrawn. Location In the books you can see the elves took a lot of convincing to get involved in what they thought of as the troubles of men, they tended to keep to themselves in their last strongholds of Mirkwood, Rivendell and Lorien. I would suggest that there are some similarly remote parts of the world which they would withdraw to, some parts of the Himalayas or deep in the Rocky mountains. Elves do not feel cold so the cooler temperatures wouldn't impact them, however they do love growing things, perhaps somewhere like the Boreal Forest. They would have lived their for millenia so as well as being repetitively quiet many myths and legends would have developed around these places. Technology I don't believe the technological world would hold much interest to an elf. As far as I'm aware throughout the books the elves do not make any technological advances. Their culture is very stagnant, they simply remain young for ever (there are some great questions on SciFi.SE about the doom of the elves and Galadriel's ring to slow the impact of time). I don't envisage science and gadgetry being picked up by their communities, that's not to say the odd rebellious elf wouldn't use carbon fibre arrows but I consider it unlikely they would switch to machine guns or start tweeting their views online. [Answer] I think the answer here is both. First they would resist, then embrace. First they would fight against technological change. The most prominent reason that a cultural or racial group rejects technology is that it threatens their way of life and there is generally backlash at the source of the threat. This can come from a variety of sources. * Rapid Change * Loss of social identity > > [From Wikipedia](http://en.wikipedia.org/wiki/Social_identity_model_of_deindividuation_effects): The SIDE model provides an alternative explanation for effects of > anonymity and other "deindividuating" factors that classic > deindividuation theory[1](http://en.wikipedia.org/wiki/Social_identity_model_of_deindividuation_effects)[2] cannot adequately explain. The model > suggests that anonymity changes the relative salience of personal vs. > social identity, and thereby can have a profound effect on group > behavior. > > > * Threatening financial well being (They took our jobs) > > From Wikipedia: Technophobia began to gain national and international attention as a > movement with the dawn of the Industrial Revolution. With the > development of new machines able to do the work of skilled craftsmen > using unskilled, underpaid men, women, and children, those who worked > a trade began to fear for their livelihoods. In 1675, a group of > weavers destroyed machines that replaced their jobs. By 1727, the > destruction had become so prevalent that Parliament made the > demolition of machines a capital offense. > > > * Relative deprivation compared to other groups. I don't have a source but modern terrorism in many cases capitalizes on this feeling of discontent. The logical progression of this could follow a few different paths which would be impacted by events in the world around them, but the most likely for the elves would at first resist change. They would not accept modern technology and may in fact have a societal legal ban on the use of modern technology. (There would always be fringe elements interested). Like isolationism in the 19th-20th centuries, which is similar conceptually, eventually the Elves would come around. The most likely scenario is violent conflict. For example the U.S. and Japan were both pulled out of isolationist policies by World Wars. That said in a more peaceful world, where the other races didn't bother the Elves this is still the likely outcome. The tides of globalization and technological advancement have proven themselves pretty impossible to resist thus far in history, that isn't to say we never go backwards as there is intense push-back against the idea but its hard to hold back the tide for long. When elves finally do accept technology it would obviously be 'Green' energy. [Answer] They could choose to do anything. They have free will and realistically they are most likely to follow the most persuasive leader. Just like any society there are differing opinions and agendas. So when building your world and making decisions they are going to be the result of the lead of a popular and trusted figure. It is these differences that are used in many worlds to create divisions that lead variations like the moon, wood, and dark elves. [Answer] If elves and the other races existed, society would have evolved into a very different shape from what we know. Specially if we consider the existence of magic. Magic in a given moment may have evolved into a sort of technology supplying many of the functions our technology does. I assume "Tolkinian" elves with their natural affinity to magic would be in a strong position in this case chances are that a strong caste system had evolved or that the elves (and maybe others) had been able to maneuver themselves into positions of power. ]
[Question] [ In a story I am working on, I need a scene in which one of the main characters finds himself outside in precarious weather conditions, unable to see unaided much farther out than an armlength or so. For the purposes of this question the setting is essentially our Earth, and my draft geographical location (which isn't vitally important; I can fairly easily change this if it's easier to make it work somewhere else, as there aren't many outdoors-settings-sensitive scenes and much of what I've done is in a sort of prototyping stage anyway) is somewhere in the far northern or northeastern parts of Canada. The time of year is tentatively mid-February, which means temperatures in the range -30 to -35 °C are [not at all unreasonable](https://en.wikipedia.org/wiki/Nunavut#Climate) and anywhere down to about -45 °C might well be plausible if there is a bit of a cold spell. At the time and place I have in mind currently the sun is just around the horizon. I've been considering having Our Hero outside at a time when the weather shifts from quite decent (just cold) to strong wind with heavy snowfall (basically a white-out), possibly coupled with a fog to further reduce visibility. * Is a (preferably quickly developing or approaching, but I'll take what I can get) fog realistic at those temperatures? Is there any particular setting element, or earlier weather, which would increase or decrease the realism of that? (Presence or absence of bodies of water, lowland/highland/flatland/mountainous region, recent shift in weather conditions, ...) * Is combining a fog with a snowstorm (or at least strong wind, which can be put into service to whirl up snow on the ground from recent snowfall) realistic? Again, is there anything in particular which can affect the realism of it? Bonus question: * Are there any particular, probable effects of those conditions on soon-to-follow weather which I should take into consideration for the following scenes for the depiction to be as realistic as is reasonably possible? What I want is the situation described at the top. Answers which address how to put the character in such a situation, if they explain why my idea won't work, are also welcome. [Answer] My answer is yes, you get fog in these conditions. Might not be traditional fog, but it's an icy haze that resembles fog and tends to leave ice crystals everywhere. You need an open water source (rivers usually...the center of them never fully freeze) and then an intenser cold front to wander through. The open water provides heat and water vapour, while the incoming cold turns it to an icy fog. It might not be the same type of 'fog', but it sure looks like it. > > Is a (preferably quickly developing or approaching, but I'll take what I can get) fog realistic at those temperatures? Is there any particular setting element, or earlier weather, which would increase or decrease the realism of that? (Presence or absence of bodies of water, lowland/highland/flatland/mountainous region, recent shift in weather conditions, ...) > > > Yes. In between the mass of cold arctic air from the north and the warmer wetter air to the south, you get a jetstream (high wind area). this jetstream can fluctuate north and south relatively rapidly and shift temperatures from warm and wet to cold and dry in a matter of a few minutes (In Calgary Canada, there's the general saying...if you don't like the weather, wait 5 minutes...I've personally seen 10 degrees and relatively nice, to -20 and cold as \\\\ and then back to +15 in a matter of an hour. Look up 'Chinook' if you want the local term for it). This rapid shift can lead to quick fogging around the river. I think the body of water presence is definitely required...the position of Calgary beside the mountains and plains tends to see higher winds which bring in the shift from cold to warm faster. So yes to the decent cold to full on blizzard in a very short time frame too. > > Is combining a fog with a snowstorm (or at least strong wind, which can be put into service to whirl up snow on the ground from recent snowfall) realistic? Again, is there anything in particular which can affect the realism of it? > > > Not sure here...the fogging effect usually requires much more still air, otherwise it dissipates faster than it's formed. Admittedly, in a full white out snow storm it'd be tough to make out if there is fog or not ;) Snow storms tend to be large weather fronts that hit a larger area, while ice-fog is a generally a localized effect. I can see the switch from icefog (still air) to a massive blizzard...but I have more difficulties seeing a massive snowstorm followed up by fog. Honestly a blizzard being near white-out and having fog to 'further obscure visibility' is kinda like putting on a blindfold and then turning out the lights...blindfold (the white-out) is far more inhibiting than turning the lights out (fog). Remember that light plays a big role in this. It is a 'whiteout'...even fully obscured by snow, there is actually quite a bit of light hitting everything as it reflects from snow flak to snowflake. It can be quite bright if you're in it during the middle of the day. > > Are there any particular, probable effects of those conditions on soon-to-follow weather which I should take into consideration for the following scenes for the depiction to be as realistic as is reasonably possible? > > > very often the storm front moves to the south, leaving behind a high pressure arctic system...cold and very clear air with little clouds. This leaves you with everything covered in a very reflective environment (white snow reflects almost all light) and a clear day with plenty of sunlight (snow-blindness becomes an issue here). If the wind dies down, the result tends to be overtly large and soft snowflakes fluttering around. And a final note - of particular nastiness when in a blizzard is the wind can and will freeze your eyes. The natural defence of course is to squint, but the hard winds will also cause your eyes to water. Watery eyes plus squinting can result in frozen eyelashes that refuse to open beyond a squint. [Answer] Contrary to the previous answers, as someone who actually lives in these climes, I can tell you that yes, absolutely, you can have fog at these temperatures. It is not, however, your "typical" fog -- around here we call it "ice fog"1, because it is literally tiny ice crystals that have formed around microscopic particulates in the air (water being capable in the conditions around here of actually being liquid down to -40C/F), but the effect is the same and any reasonable observer looking at it (and not thinking about just how gorram cold -40F/C actually is) would reasonably conclude that it is fog. Those of us who live around here quite frequently just call it "fog", in fact. So there's two possibilities for your character: * He's not a local, in which case it looks and acts just like fog and he'd reasonably call it "fog". * He is a local, and knows full well what it actually is, but just like the locals used to the stuff he reasonably calls it "fog". An interesting feature of ice fog is that it leaves a fine dusting of "dirty" ice crystals on absolutely every exposed surface, whether horizontal or vertical. Not really noticeable on snow-covered ground, of course, but you'd see it on buildings and streets (where, incidentally, it makes them quite slick!). Your best bet to get an ice fog is to drop the temp rather rapidly from "warm" (that is, somewhere around -10 to -20F/-20 to -30C) to "absolutely frigid" -- a drop of around 20 degrees F (about 10 degrees C) will do it quite easily. You have to have around 100% humidity (or darn close), but keep in mind that that means "100% of the humidity air this cold can hold", which is a heckuva lot drier than, say, 10% humidity in a Texas Gulf Coast spring. Pollution helps (it adds particulates, though it doesn't have to be anywhere near San Francisco smog-levels), but is not required. That's not the only way, you can go to bed one day at -40F/C and wake up the next morning to pea soup ice fog and it's still the same -40F/C. Weather's crazy like that. That's just your easiest route to ice fog, but really you can have almost any weather you want and you can realistically get it. Of note however is that it cannot form below -40F/C, nor will it form if you've just warmed up past that point (and, really, it's exceedingly rare to see it when temps are climbing anyway -- it almost exclusive forms when they fall). It can stick around if it forms and then the temps drop below that point, of course, but the ice crystals will begin sublimating and it won't last long. That said, a strong wind would most likely simply blow it away -- being floating ice crystals rather than proper moisture, it seems far more susceptible to wind. (That's merely my subjective observations of literally 30+ years living with this stuff.) However, you absolutely do not need it -- when you have driving winds whipping snow up off the ground as well as fresh snow falling from the sky ("whiteout"), you can't see your own hand in front of your face. It's not merely that there's so much snow in the air whipping around you, but also that that icy wind driving into your face provokes a reflex reaction to close your eyes, and you can barely open them enough to squint. (Wearing ski goggles helps, but unless you're actually skiing no one -- not even those of us who regularly encounter these types of conditions -- carries those around.) It's worth noting that it's not merely the snow itself blocking your vision -- what light gets through the clouds and snow reflects chaotically off of the flying snow, blinding you. "[Snow blindness](http://en.wikipedia.org/wiki/Photokeratitis)" is a common side effect of being in whiteout conditions if one's not prepared (i.e. wear your sunglasses!), and it doesn't even have to be particularly "bright" as you see it -- UV light is quite adept at punching through clouds and snow, and more than capable of blinding you! --- 1 There is another, more "technical" term for "ice fog", but it escapes me at the moment. And no, I don't mean "pogonip" that [Wikipedia mentions](http://en.wikipedia.org/wiki/Ice_fog) -- I've never heard that term. No matter, no one but meteorologists use it anyway, and not even when reporting the weather on the local news. [Answer] No, fog can not be combined with a snowstorm. Fog is a result of water evaporating and then becoming minuscule liquid particles again, floating in the air, which is very difficult at low temperatures, and can not happen under 0C. At these temperatures, liquid water solidifies and, in turn, can sublimate, but there will not be liquid water floating in the air (which is what fog is). Instead, you can have a good amount of snow dust (solid water, instead of liquid) floating in the air. The effect is the same, but you just use the correct state for the water. [Answer] In my experience, no. Fog doesn't work with cold, at least not that cold. When you are getting to those temperatures your breath crystallizes a few inches from your mouth. You can feel the cold trying to freeze your lungs. a brisk walk down a hill and you need to blink frequently to keep your eyes from freezing. Those temps would squeeze the moisture out of the air and could make one hell of a snow storm if it came up fast. I've been in snow storms were you really couldn't see more than a few yards and when the wind is really blowing it's hard even to keep your eyes open. I was in a XC ski race at -40, one of the racers had to go the hospital because of frozen eyeballs. I'm assuming just the corneas but never heard the specifics. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 1 year ago. This post was edited and submitted for review 1 year ago and failed to reopen the post: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/227504/edit) First Contact In 2020s an alien starship visited Earth. First contact was peaceful - with intial contact made from orbit, humans started learning the alien language and the aliens - let's call them Species A - started learning English and communication was established. Eventually the aliens were invited to land to meet in person with representatives of the UN. But the intial talks reveal there is a problem: Earth and Sol System lie in the middle of territory of a large interstellar empire. Species A is not willing to give up its rightful territory, so aliens deem it necessary to integrate Earth into the Empire. The Terms Specifics are up for negotiations, but there are a few specific points which are not up for debate: * Earth must demilitarize - all militaries are to be disbanded and WMDs in particular are to be disposed of. Personal weapons and police forces are irrelevant. * A governor of Earth will be appointed. That governor must be of Species A * Earth must host an alien military garrison * Aliens will build a space station in Earth orbit, to act primarily as transit and communications point but also a military fleet outpost * Humans will not receive citizenship, but will instead be given permanent resident status - sharing that distinction with about 20 other species. Only Species A has full imperial citizenship, but residents are far from having no rights. The alternative to integration is violence, but as aliens think it would be a shame to desolate a near-perfectly habitable planet, a peaceful solution is preferred, even if getting humans to give up their independence will be tricky. With that in place: How could Earth be peacefully integrated into the alien Empire? I am asking about what could be the possible and likely terms and the process that could realistically lead to peaceful integration of Earthlings. EDIT in response to comments: What do the aliens want from Earth - first and foremost they don't want an unsupervised developing civilization in the middle of their territory. Apart from that: habitable land, resources, workforce, trade, refueling and maintenance facilities for starships... With that said, they would also invest in Earth, rather than just exploit it. [Answer] ## How does 'empire' translate across species barriers? Present-day mankind is probably extremely far away from interstellar travel. It could be that it is a simple Doh! insight and we cannot explain how we failed to discover it ourselves, but probably there are many different technologies involved in routine starflight. We don't even have routine orbital travel yet. No high-efficiency surface-to-orbit transport (I'm talking of the payload ratios and costs of an airliner, not three guys on top of a disposable fireworks container). No real artificial ecologies. And so on. Then the aliens arrive in orbit. If they are careful, first in high orbit, beyond the reach of most human [anti-satellite weapons](https://en.wikipedia.org/wiki/Anti-satellite_weapon). They communicate, they send shuttles down, they start negotiations. Then they appoint an ambassador. At least that's how the humans understand it. As the aliens see it, "imperial representative to contacted planets" is more like governor, and of course the representative is from species A ... The aliens begin to trade, and offer mankind provisional membership in their interstellar trade organization. That's how it comes across to most human translators. A few maverick analysts might insist that they're talking about submission to their empire, but there is no talk of tribute or taxes at this point. Humans might be allowed/invited to travel to other planets of the empire/trade organization, with subsidized tickets. Of course they are not full citizens when they arrive, they are tourists or business travelers. Perhaps students. Getting mankind to disarm without ruffling any feathers will be difficult. But as a first step, the aliens could threaten that there will be consequences if the humans develop, test, and deploy weapons to hit starships in high orbit. Either threats of military action, or of economic sanctions. The aliens have so much technology to offer, but they won't do that until mankind gets their house in order. No wars, a sort of planetary government, general disarmament. The ambassador/governor will establish a compound, under alien jurisdiction. With armed guards. At first these embassy guards have no jurisdiction outside the embassy compound. But then they offer technological aid missions on the condition that their teachers will have guards at need. They build the orbital transfer station for Earth, too. Having more than one isn't how it is done. There are quarantine procedures for interstellar flight, documents to be checked, each world has one orbital starport. But the ISS would fit into the hangar of one of their starliners, not the other way around. And even if mankind did come up with a sufficiently large station, they wouldn't have artificial gravity, or tractor beams, or standard docking beacons. As mankind learns more about the aliens, they find out that only species A has full citizenship in that trade union, and that there are rival trade unions. And that switching unions is not acceptable. [Answer] *Space colonialism* Yeah, sadly what you are describing: coming on in a position of strenght and imposing your rule on another civilisation to integrate it in your own empire. it is space colonialism and there is no way around it. there is a very low likelyhood that there wouldn't be any kind of anti alien/integration movement, simply by what you are asking humand to give up. And you are not talking about what the alien want from earth, but it will influence how quickly people want to flip you off. if you just siphon ressources and not give anything back, you won't be able to do that peacfully. *how to mitigate the anger?* first thing that need to go if you ever want a semblance of peace is to give the governor post to a human or an institution. do something akin to europe where each state keep. if you federalise all of earth into one system you are bound to have an unified protest movement. if you let each state autnomous you have less power, but at least it will be much more peacful. *how to get the goods out* take a book from the cargo cult and negociate in human term in the same kind of moral term. so far, human are in a capitalistic society. therefore if all or at least most of your deal are done in a capitalist framwork, you will have a much easier time implementing new thing. If you impose a new kind of society/framwork, it might be better for you in the long term, but it will cause a lot of friction. *the weapon question* Is your millitary unable to deal with 21st century weaponry? let's suppose nuke are the only system that truly bother you, but most of the modern military equipement are extremly underwhelming against your forces. A lot of state will be EXTREMLY worried by your demand and they won't like throwing their weapon away and if you ask them to do so they will think they can chalenge you. where as imposing yourself as a peace enforcer that can essencially smite belligerant from one or both side with ease is a much better solution: you guarantee peace (at least for those who side with you) and spell doom for those that disturb peace it is an easy way to buy support also, as it could give you a veniere of legitimacy when you slap some dissident. With a long enough framwork and some bilateral deal you will see most military get mostly disbanded. (just look at europe & nato menber, a lot of state far from russia are more and more rellying on other for their defenses.) for the nuke it will take longuer but taking them by force would not look good. *Culture war* Take another page from hollywood. the american media machine is an extremly effective propaganda tool on the global scale, but now imagine if you had the budget of a star empire! spend a lot of money to translate all of your big moovie and flood earth with media that will help spreanding the message about how cool you are. if your own citizen & other alien races come to earth you need to be very careful about their shown wealth: if they start to see all of those fancy alien rich as possible while they themself are far from uplifted, you will quickly have thing to answer for. to keep peace you will have to insure that all of the denizen of earth have a standard of life similar to those of the empire, even if not citizen per say *In conclusion* of course, all of this is if you ACTUALLY want peace and collaboration. if you want a cheap colony, you can have it, but it is never peacfull for long. the contradiction of colonialism is alway rising sadly: when you are integrated in an empire, you will rightly want the same standard of living as mainland citizen because you wille ventually know what they have, and therefore you will cost most more and more. [Answer] Perhaps the route used by the aliens from Arthur C Clarke's a childhood's end would work. The aliens (the Overlords) remained high up dozens of miles above the Earth and did not show themselves except by radio transmissions and discussion with a few diplomats (not face to face). They used and developed the apparatus of the United Nations to impose their will slowly over time. Some of the technologies they used: A device that enabled the aliens to communicate directly with anyone on Earth with no obvious external signs they are doing so. To the recipient it felt like they were hearing voices in their head. These voices might appear as subtle whispers or the voice of god. They might play on key aspects of the recipients personality and emotional make up. They might make gentle suggestions, provide reassurance or make threats or just produce incessant noise. They might affect anyone in a powerful position and might occur frequently, occasionally or not at all. And the existence of this means of coercion was never mentioned. Such a device could have a very powerful effect. No tyrant would want to admit to hearing voices or to the fact that they couldn't sleep at night due to hearing the same message from their grandmother repeated over and over about cabbages. No military force would be effective if senior commanders became deranged or decided to attack friendly forces or surrender or retreat. Another technology employed was a polarizing field that could be deployed anywhere around the world over a large area that reduced sunlight to a feeble twilight. This could be used to target particularly difficult countries as a demonstration of force and to sap popular support. Nuclear weapons were used against the Overlords ships on one occasion. Missiles were launched and appeared to hit the Overlords ship, but there was no explosion or sign of damage they just disappeared. The Overlords simply ignored the attack as if nothing had happened. Attempts to block the media could be thwarted allowing a greater access to truthful information as well as subtle alien propaganda and direction. Over many decades humanity was guided away from warfare into a more prosperous and settled world. Everything was working very nicely until... but I won't spoil the story. [Answer] They only need to convince people in charge and don't upset status quo There is no need to convince all humans to join the empire, just cut a deal with politicians and billionaires, they have more than enough experience and influence to do the rest, just leave them in power and give them some new toys; longer lives, new tech, maybe some exclusive trade contracts. It's cheap and easy. On the other hand, if aliens would interfere with earth's politics i.e. upset status quo, especially by changing people in power...well. They would be shown as enemies and war would break out. [Answer] One State at a time. Begin with the autocratic states. Demand a surrender, directly from the leaders. If they refuse, destroy the leader, publicly. Brutally. Remotely. Then demand a surrender from the new leader. Anybody that fires on them, missiles or guns or so much as throwing a rock, destroy them. If it is done by subterfuge, exact a price on the adults in the area. Prove your superiority. You want a peaceful transition, but resistance is futile, if you humans would rather turn your little part of the world into a smoking ruin, so be it. There are other worlds. There are more of us on the way. WMD's should be easy for them to detect. Stand down. We are not colonists, we need nothing from you. You will join civilization, or cease to exist. That is your choice. [Answer] ## It is not going to work There are basically two approaches. Hands-off and Hands-on. ## Hands-off Like [Shas'](https://worldbuilding.stackexchange.com/a/227505/10324) and [o.m.'s](https://worldbuilding.stackexchange.com/a/227510/10324) answers. The aliens have absolute power over space. But humanity rules the ground. The problem is humanity is not going to demilitarize or otherwise obey the overlords without a fight. They can dress it up as nicely as they want, we know a colonization attempt when we see one, and we want none of it. ## Hands-on Like [Amadeus'](https://worldbuilding.stackexchange.com/a/227515/10324) answer. The aliens land and brutally kills anybody who looks at them funny. Or has weapons. Or sticks that looks like weapons from a certain angle. Or uniforms. Or vaguely similar clothing. Well, that works. For a while. But it doesn't end. There will always be more rebels. And any humans who are appointed rulers by the invaders will be called collaborators and targeted even harder by the rebels. Apart from never reaching the "peaceful" point asked for, the whole affair will also be a economic disaster for the invaders. Invasion is hideously expensive. Those exports they were expecting? It turns out that when one in a million boxes contains high explosive it cuts badly into their profit margins. At some point, an alien accountant will point out that it would be vastly cheaper to just kill off our whole species. ## But don't listen to me! This is not my story. It is yours. Feel free to write a story where it works. But you should at least give a nod to these problems. Don't pretend that it is easy. ]
[Question] [ If hawks or eagles (or any creature that can fly like a hawk) had the same ability to pronounce words as parrots but also had consciousness (what I mean by that is that they can scout and describe the enemy movement to their side), would that extra capability of their brain hinder their flight? The ways I imagine it would hinder their flight: 1. The brain size would need to be larger to allow them to have speech and higher-than-normal memory. 2. The brain would require more blood adding to the very energy expensive process of flying. If it does hinder flight, what are ways to make it scientifically possible (without magic)? [Answer] We don't know what is necessary for human level intelligence, so let's take the human brain as a starting point, and look at three characteristics: * weight: our brains weigh about 1.5 kg. As noted by @Slarty, some humans show intelligence with almost half their brain removed, so there's probably some room to maneuver. * calories: our brains require [at least 260 kcal a day To function](https://www.scientificamerican.com/article/thinking-hard-calories/). * blood supply: our brains require about 750 millilitres per minute, or 15% of the cardiac output The largest animal known to be able to fly is the [Quetzalcoatlus](https://en.wikipedia.org/wiki/Quetzalcoatlus). Conservative estimates of its weight are around 80 kg, with 250 kg more likely. This puts it in range of a human body, so it makes it a good candidate. Step one, brain weight. Can we put 1.5 kg of brain into the Quetzalcoatlus' head without breaking stuff? One promising target is the gigantic beak. If we change the intelligent bird's diet (and require them to speak) we may be able to get rid of 90% of the beak and replace that weight by a brain. I can't find the weight of a Quetzalcoatlus skull, but in humans, the entire skeleton is about 15% of our weight, and despite having hollow bones, [birds' skeletons have roughly the same weight](https://www.umass.edu/newsoffice/article/bird-bones-may-be-hollow-they-are-also-heavy-says-umass-amherst-biologist). With that figure, conservatively estimating the beak to be one twentieth of the skeleton, we get a weight saving of about 0.5kg if we shorten the beak by 90%, if the body weight is 70kg. For less conservative estimates of the body weight, we get closer to 1.5kg. Next up, calories. For non-passerine birds, the calorie intake per kg is [pretty similar to mammals](https://www.world-builders.org/lessons/less/biomes/annutrita.html). Assuming 70kg body weight, we get around 2000 kcal, assuming 200kg, we get 5000 kcal. Either way, the 260 kcal required for the brain to operate is a relatively small addition, which can probably be handwaved by making the available food a bit more nutritious (possibly as a result of the intelligence increasing with evolution, as it was for humans). Finally, blood supply. The neck of the Quetzalcoatl is long, requiring a powerful heart to get enough blood up there. Giraffes have a similar configuration. Their brains weigh half of what a human brain weighs, and they require an 11 kg heart to supply it with blood. Adding 10kg to a 70kg pterosaur might be a deal breaker. In a 200kg beast, there's probably a bit more wiggleroom. One obvious solution is to shorten the neck. While many large birds have long necks, others, like bustards and condors have short necks, so the reason the Quetzalcoatlus had a long neck may be more to do with feeding than aerodynamics. So, starting with the (likely sizeable) heart the Quetzalcoatlus already had, if we shorten the neck and the beak, we can keep the cardiac output the same, sending more blood to the brain. As a bonus, since the smaller beak puts the center of mass of the skull closer to the end of the neck, less muscle tissue is required in the neck, which also means more blood for the brain. I'm sure I've missed something, but looking at these considerations, it seems plausible to put a human brain into something ythat flies the way a Quetzalcoatlus did. Update after comment What can we do if we limit ourselves to the basic dimensions of a bald eagle? It is estimated that the maximum wing loading (amount of weight per unit of wing surface) for animals is 20 kg/m^2. I can't find the wing surface of a bald eagle but I recon that with a wing span of 2m, a single square meter is reasonable (the wings are about a quarter as deep as they are wide). In other words the bald eagle is much lighter than its maximum weight. Swans have roughly the same wingspan at twice the weight, so this bears out. They also have much more trouble taking off, so at 12kg we are probably approaching the limit of what nature can do with a 2m wingspan. So, at 6kg for a standard bald eagle, there is plenty of room to fit in a 1.5kg brain and still be able to lift off. A bald eagle's diet is about 150 kcal, so it would need to more than double its intake to 310. Cooked food and agriculture should get you some of the way there, but you can also give a much richer natural source of nutrition. The total [cardiac output of a pigeon](http://people.eku.edu/ritchisong/birdcirculatory.html) is 200 ml/min at rest, and 1000 ml/min active. Assuming that this scales linearly, the bald eagle's heart produces about 1200ml/min at rest, which we need to almost double to accommodate the new brain (we can ignore the output required to supply the original 12 grams of brain). Heart mass and cardiac output have [a linear relation](https://www.researchgate.net/publication/237057186_Highly_Athletic_Terrestrial_Mammals_Horses_and_Dogs/figures?lo=1) so we need to double the size of the heart, and probably the lungs as well. The heart mass for anything weighing 6kg is no more than a few tens of grams, so that easily fits our weight budget. Lung mass is closer to a few hundred grams, but still easy enough to double without getting into trouble. Finally, at this size the skull volume is a big problem. We need to up the cranial capacity from 16 to 1000 cubic cm. Note that this seems worse than it is, due to the cubic relation between scale and volume. Quadrupling the length, width and height of the head would be enough. This would change the proportion of the head and body to something like a toucan. Its head would be around 1/10 of its body. It would be difficult to keep this aerodynamic, but shrinking the brain to the minimum required for intelligence, putting much more brain matter in the nervous system, and elongating it into the neck will go a long way. In short, I guess you'd end up with something that looks like a swan without a neck, and with giant head, but I think it can work. [Answer] It's noted in [this paper](https://www.pnas.org/content/113/26/7255) that birds have evolved brains that have a significantly higher density of neurons than mammals, and it's also said the neurons are smaller, which along with less volume of cerebrospinal fluid for a given number of neurons would mean more neurons per unit of brain mass. > > With their higher neuronal densities (Fig. 3 A–C), songbird and parrot brains accommodate about twice as many neurons as primate brains of the same mass and two to four times more neurons than rodent brains of equivalent mass (Fig. 1B). > > > The paper also notes that birds have a higher proportion of their neurons in the [pallium](https://en.wikipedia.org/wiki/Pallium_(neuroanatomy)), the parts of mammal and bird brains that are responsible for the more complex and flexible forms of cognition (in mammals the pallium is mainly the cerebral cortex, in birds it's just called the pallium but has [convergently evolved](https://science.sciencemag.org/content/362/6411/190/tab-figures-data) to play a similar role, see the articles [here](https://www.nsf.gov/news/news_summ.jsp?cntn_id=100744&org=olpa&from=news) and [here](https://www.nature.com/articles/s41598-018-28301-4) on how it functions similarly to the mammalian cortex). The paper talks about the increased proportion of neurons in birds' [telencephalon](https://en.wikipedia.org/wiki/Cerebrum), which in mammals includes the cortex (pallium) and the [basal ganglia](https://en.wikipedia.org/wiki/Basal_ganglia) (subpallium): > > Thus, in contrast to mammals, larger brains of songbirds and parrots contain increasing proportions of neurons in the telencephalon, and correspondingly decreasing proportions of brain neurons in the cerebellum and other brain regions (Fig. 4 C and D). Neuronal densities in the avian pallium exceed those observed in the primate pallium by a factor of 3–4 (Fig. 3A). Hence, the telencephalon houses 38–62% of all brain neurons in songbirds and 53–78% in parrots (Fig. 4C); the pallium houses 33–55% in songbirds and 46–61% in parrots (Fig. 3D and Table S4). This markedly contrasts with the situation found in mammals, in which the pallium accounts for most of total brain volume, but the cerebellum houses a large majority of brain neuron > > > The paper concludes: > > Our finding of greater than primate-like numbers of neurons in the pallium of parrots and songbirds suggests that the large absolute numbers of telencephalic neurons in these two clades provide a means of increasing computational capacity, supporting their advanced behavioral and cognitive complexity, despite their physically smaller brains. Moreover, a short interneuronal distance, the corollary of the extremely high packing densities of their telencephalic neurons, likely results in a high speed of information processing, which may further enhance cognitive abilities of these birds. Thus, the nuclear architecture of the avian brain appears to exhibit more efficient packing of neurons and their interconnections than the layered architecture of the mammalian neocortex. > > > [This paper](https://www.frontiersin.org/articles/10.3389/neuro.09.031.2009/full) says the human cerebral cortex has an average mass of 1233 grams, so if we assume a bird with human-like intelligence would have about the same number of neurons in its pallium but at half the mass that would be around 600 grams, and if we assume around 60% of the mass is in the pallium, the whole brain would have a mass of about 1000 grams. (Though it may be that while 60% is close to the maximum in terms of how pallium-dominated a smaller brain could be, with larger brains the proportion of brain mass taken up by the pallium could be even larger--[this article](https://www.pnas.org/content/109/Supplement_1/10661) notes that 'Although the human cerebral cortex is the largest among mammals in its relative size, at 75.5% (4), 75.7% (5), or even 84.0% (6) of the entire brain mass or volume, other animals, primate and nonprimate, are not far behind: The cerebral cortex represents 73.0% of the entire brain mass in the chimpanzee (7), 74.5% in the horse, and 73.4% in the short-finned whale (3).' So, maybe it wouldn't be too unrealistic to have a bird with human-level intelligence and a brain with a mass of only say 0.7 kg.) This is quite a bit heavier than any existing brain ([this article](https://arstechnica.com/science/2016/06/bird-brains-are-densewith-neurons/) says Macaws have some of the heaviest brains at around 25 grams), but if you assume a bird with a larger body size than a Macaw perhaps it could fly with a 1 kg brain, especially if it could tuck its head back to rest on the body the way [pelicans do](https://www.allposters.com/-sp/Great-Eastern-White-Pelican-Flying-Chobe-National-Park-Botswana-Posters_i5262585_.htm): [![enter image description here](https://i.stack.imgur.com/Agy4i.jpg)](https://i.stack.imgur.com/Agy4i.jpg) And [this article](https://animals.howstuffworks.com/birds/pelican-bill-vs-belly.htm) notes a pelican can weigh up to about 13.6 kg, so perhaps a brain of around 1 kg or a little less wouldn't be too much to make flying impossible for a bird the size of a large pelican. Larger pelicans like the great white pelican have big wingspans, [this article](https://en.wikipedia.org/wiki/Great_white_pelican) says 2.3 - 3.6 meters (7.4 - 11.8 feet), so if you want a bird significantly smaller than that might be difficult (if you want something like an intelligent bird of prey, there was a [giant prehistoric eagle](https://en.wikipedia.org/wiki/Haast%27s_eagle) in this size range). [Answer] A human level of capabilities can be maintained with a significantly smaller brain as can be seen from the many cases of people with a range of abnormal brains leading normal or near normal lives. So given a very large bird body it is conceivable that a large enough brain could be fitted into the skull to enable quite advanced cognitive functions. How that combination might evolve is another matter. ]
[Question] [ I am currently working in a "fantasy" world without any kind of magic and I thought of a race with different skeleton color (blackish in particular but I want to know in general). I am not well versed in biology but may I guess the white in our bones is from the calcium phosphate that forms them? So, is there any other component that could realisticly (to a certain extent) form an skeleton of different color? In particular black/grey. Maybe there is a way of getting pigmented bones by adding other component to the mix? Hope I made myself clear as I could not find any information related to this topic in these forums nor other. I would love to keep my world as realistic as possible. Thanks in advance for your answers! [Answer] Like bones, which are made of calcium phosphate, [seashells](https://en.wikipedia.org/wiki/Seashell) are made from a calcium compound, [calcium carbonate](https://en.wikipedia.org/wiki/Calcium_carbonate). Calcium cabonate is white, like bone, and yet many mussels build colorful shells. In fact, [some mussels are black](https://en.wikipedia.org/wiki/Black_mussel): [![black mussels](https://i.stack.imgur.com/V3piq.jpg)](https://i.stack.imgur.com/V3piq.jpg) The colors in sheashells comes from pigments. So the bones in your story contain black pigment. The evolutionary purpose of the black chemial might be that it: * prevents a certain infection of the bones because it is antifungal, antiviral, antimicrobial, antiparasitic or the like * makes the bones more stable / flexible / harder * serves no purpose but is contained in the food and is chemically prone to bind with some component of the bone [Answer] Bones are whitish because of their chemical composition. When alive, bones are white~yellow~red because of the mineral, fat and bloody components. Dead dry bone is white because of calcium phosphate which makes up a large portion of the mineral content. In order to get another colour, you have two choices: 1. Start all over by reinventing biology. Choose a different evolutionary path that will use a compound other a metal phosphate mineral. 2. Look for similar metal phosphates that have other colour schemes. You could try something like [herderite](https://en.wikipedia.org/wiki/Herderite), which is calcium beryllium phosphate. It can be greenish or yellowish or clearish. I make no guarantees about the primary world biological validity of such a substitution, because a) handwavium and b) fantasy world necessities and all. You'll have to do some homework on your own, but I think this will give you a possible line of research! I'll only note that most metal phosphates seem to be whitish or have muted colours. You may need another additive to get black bones. [Answer] Asphaltenes. [![smilodon tar stained skeleton](https://i.stack.imgur.com/83xQJ.jpg)](https://i.stack.imgur.com/83xQJ.jpg) [https://commons.wikimedia.org/wiki/File:Smilodon\_californicus\_saber-toothed\_tiger\_(La\_Brea\_Asphalt,\_Upper\_Pleistocene;\_Rancho\_La\_Brea\_tar\_pits,\_Los\_Angeles,\_southern\_California,\_USA)1(15420357246).jpg](https://commons.wikimedia.org/wiki/File:Smilodon_californicus_saber-toothed_tiger_(La_Brea_Asphalt,_Upper_Pleistocene;_Rancho_La_Brea_tar_pits,_Los_Angeles,_southern_California,_USA)_1_(15420357246).jpg) The bones retrieved from the La Brea tar pits are stained an impressive greasy black. That is from sitting in the tar after they died. If your creatures had circulating tar-like substances in their blood from their food supply, their bones might be stained black in life. [Asphaltenes](https://en.wikipedia.org/wiki/Asphaltene) is the catchall for these persistent gooey hydrocarbons as they occur in tar pits and elsewhere. > > Asphaltenes consist primarily of carbon, hydrogen, nitrogen, oxygen, > and sulfur, as well as trace amounts of vanadium and nickel... > Asphaltenes are defined operationally as the n-heptane insoluble, > toluene soluble component of a carbonaceous material such as crude > oil, bitumen, or coal. Asphaltenes have been shown to have a > distribution of molecular masses in the range of 400 u to 1500 u, but > the average and maximum values are difficult to determine due to > aggregation of the molecules in solution. The molecular structure of > asphaltenes is difficult to determine because the molecules tend to > stick together in solution. These materials are extremely complex > mixtures containing hundreds or even thousands of individual chemical > species. > > > I could imagine circulating globs of asphaltene might contribute to accelerated blood clotting, or serve an immunogenic role in sticking to and inactivating parasites. Imagine a mosquito drying to drink blood containing this tenacious goo. In addition to black bones, your creatures would smell like tar and have thick black blood. If you heated it enough, once you boiled off the water the residual asphaltenes would burn and probably produce a lot of dirty brown smoke. [Answer] I see this is an old question and I hope that the reply could still be relevant. Nobody mentioned Alkaptonuria, which is a rare genetic condition. It is also known as black bone desease, so I thought it deserved a place in here. I am not an expert so I could not elaborate properly all the chemical processeses, but this desease just suggests us that bones can actually be black. In the following image you can see an elbow joint area. On the right you can see the olecranon and the radial head of the ulna and radius respectively; on the left you can see the capitulum and trochlea of the humerus. [![Cartilage of an elbow](https://i.stack.imgur.com/2QhyY.jpg)](https://i.stack.imgur.com/2QhyY.jpg) To my knowledge, the body accumulates homogentistic acid which causes the dark color when it oxides (it also causes urine to be brownish/blackish), but maybe someone else could elaborate this more and better. I am not really sure how you can put this in a fantasy story, maybe this different race has a natural way to manage properly this acid, causing urine, skin and bones to be darker without all the bad things this desease does. [Answer] ## You are worried about a non-issue, just add something that acts as a pigment Bone is a mix of calcium phosphate and various proteins, if one of those proteins happens to have a color it will color the bone. Ingroxd already covered black bone disease but you chose whatever color you want with the right pigment, [tetracycline](https://jamanetwork.com/journals/jamaophthalmology/fullarticle/419116) can dye bone neon yellow, it also makes it fluoresce green under black light. All you need is a material or protein being deposited in the bone that has color and the bone will be colored. ]
[Question] [ So, the world has come down to a crashing halt. Nukes rain down from the sky, after the Cold War finally became a Hot War. Now, humanity is left with a wasteland. After the big one, cities have been mostly abandoned to the dying and the (soon to be) mutants. Lets say you have a man living near a large city, named Bob. Bob decides that in order to get by, he’ll brave the muties and crazies to get any loot the city holds. Bob sells these scraps of to others, and starts a small company “Bob’s Scavenging Co.”. Bob eventually dies, and his son, Bob Jr., takes over the company. How long would scavenging be economically feasible, considering that not much of what’s scavenged an be remade, and that over time things will break down? * Bobs Co. mostly Scavs off (Post apocalyptic slang for scavenging) metal scrap and stuff like that. * My story has a time frame of about 150 years. * The City they scavenge from is reasonably large, about San Francisco size. * Bob Co. supplies mostly locals, about 1,500 nearby folks [Answer] The one man supplying 1,500 people with metals for medieval-level technology will probably get everybody a basic set of gear in ~10 years. But the thing is, they will not stop at medieval technology. They will want solar panels and wind turbines, batteries and electric devices. They will want metal vehicles, pulled by horses if they cannot generate enough electric power. They will want firearms, with black powder once the modern powder runs out or expires. Moroever, there might be trade with more distant lands. SF is on the water, so travel is easy. They can get fruit from the south, timber from the North, chemicals from up the in the mountains. All in exchange for metal and high tech from SF. [Answer] Easy answer: forever We recycle scrap today. It's been going on for decades and decades and shows no end. A sizeable city (oh, let's say San Fransisco, population 884,363, since you're interested in it) would provide recyclable stuff for 1,500 people for centuries. Why do I say this? * The population ratio is 590:1, meaning for everyone Bob's supplying, there's 590 people worth of stuff to recover. * The industrial base in San Fransisco is massive. There'd be enough reasonably easily recoverable metal (buildings, cars, factory equip, etc.) to last far into the future. And this isn't counting the possibility of a big freighter ship or military vessel that would supply metal forever. * Just the local metal scrapyard would supply you for years, if not a decade. And there's a lot more than just one in SF. I could go on, but there's no need. Mutants are a problem, but resources are not. For all practical purposes for your story, if the major city is major like San Fransisco, the recyclables would go on forever. What would a practical limit be? Saturating your market. Like Bald Bear said. Eventually everyone has what they need. So, infinite supply, limited demand. Economic feasibility is in the black until you max the demand curve. Then it's in the red. [Answer] First, this is a highly speculative answer, but it pretty much has to be, given the subject involves predicting the future. So consider this my best guess, but not at all authoritative. You will start to run out of gasoline in just a few years. Once that's gone, you might be able to keep motorized things running for a few more years on biofuels and such, but then you will also start to run out of consumables like motor oil, because they also break down after a few years. Within at most a decade or two you will no longer have fossil fuel powered vehicles and tools. That's devastating. And once the people move out to the country to get away from the disease and danger of the city, the lack of motorization will make it very hard and expensive to bring scavenged goods from the city to the people. Wind and solar power will start to fail after 20 years or so, and eventually the composites in fan blades and bearings in motors will fail, and solar cells will degrade. You might be able to find enough spares to keep some solar power going for few decades or maybe even 100-200 years, but not at industrial scales. You won't be driving solar cars or running solar powered factories. Coal will make a big comeback. It's an easy fuel to use with low tech, it can power steam boilers and home heaters, and there's a very nearly unlimited supply available. You could be a coal scavenger for a long time. So the biggest problem your society will face in the medium term will be energy. Energy is the lifeblood of a modern society, and enables our standard of living. If you go back to water wheels or manual labor, your standard of living will crash back to pre-industrial levels. Most foods will be spoiled within a few years to a decade. Now you will have to grow your own. Without mechanized farm machinery, you won't be quite back to subsistence farming, because there will still be available fertilizers and knowledge of scientific farming practices, but it will be close. The standard of living of the people will plummet. There won't be enough people to maintain old infrastructure, or enough free time to invent better ways to do things. And if there are a lot of people, they will probably starve. The carrying capacity of North America is greatly dependent on mechanization, high energy farming, and the ability to transport food long distances from fertile regions to the cities. All of that will be lost. In the longer term, bearings will corrode, electronics will fail, medicines will all be extinct, concentrated fertilizer will be used up or unusable, and you will be utterly unable to replace it. Within a couple of generations you will be back to a small subsistence farming population, too busy growing food and staying alive to maintain old infrastructure. Flora and fauna will take over cities, roads will break down and become impassable, and eventually you'll have a world of small groups of subsistence farmers living out on the land and the cities will be largely abandoned. Once this state is achieved, a technological society would have to be rebuilt from scratch, and to do that will require hundreds of millions of people. So your future recovery back to today's standard of living will take as long as required to grow the population back to pre-apocalypse levels. Hundreds to thousands of years, depending on the birth and death rate. None of this includes the very real possibility of conflict. Getting people to peacefully cooperate while their standard of living craters is not easy. One possible scenario is a return to hunting and gathering because farming communities become rich targets for attack. Things like steel will be available for a long time, but without concentrated energy you won't be able to smelt it very well - at least in quantity. You will be able to re-melt it into swords and hand tools and such using ancient techniques, but you won't be building new metal buildings or anything like that. Your eventual society will probably look a lot like what the first settlers in America had, although the remnants of society will give you a permanent collection of better hand tools, and you might be able to keep interior LED lighting going with small scavenged solar panels. You might also have better housing, and there will always be enough steel and old wood beams and such to enable it. As for scavenging being economically feasible... What economy? You will be back to bartering immediately, and money will be worthless. Barter makes it harder, because you have to find the person who has exactly what you need, and you have to hope that he needs what you have. I would suspect that there will be scavengers going far into the future, but the impact of scavenging on the overall standard of living of the people will diminish rapidly over time as old stuff degrades and the people lose the free time needed to scavenge as they work most of their waking hours growing enough food to survive. [Answer] About the topic that appeared in the comments before, that a society would try to advance technologically... --- I guess keeping things real is an important thing, to ask what would probably happen. The other question is *what do you need* your world to be like? Don't forget about the effect of good storytelling - if your plot needs a high/low degree of scavenging – let's find a reason for it. With fiction you have the phenomenon of willing suspension of disbelief - people are willing to accept the rules of your fictional world*. For example some fans are angry about how Leia uses the force* in Star Wars. But no one complains about something like the force being impossible in real life at all. If there are things you want to write about, there are ways to lay out a historic backstory or scientific base to justify your world as you want it. Is it probable, that future warriors ride on dinosaurs? No. But if you want to write a story about people who live with dinosaurs, they could have been cloned from prehistoric DNA (like in Jurassic Park) or survived under the earth crust or on a remote island or somehow be biologically backcrossed chickens. Is it probable that in a world some people have magic powers? ... --- What does this mean for post apocalyptic societies? If you want a highly (re)developed society, people rediscovered a lot of technology, found many old engineering texts, maybe the "right" people survived and were clever enough to found companies and universities... in that case they might have built own primitive factories and laboratories to produce materials and technology on their own, like in "Mortal Engines", although in that novel/movie they had over 1,5 thousand years to dig out technology. If you want your world to rely mostly on scavenging and farming because you want that Mad Max feeling (but you also don't want to be first generation posties like The Walking Dead) you could argue that development is exponential: It's much easier to make groundbreaking inventions, when you have many academically tought experts who are able to communicate with other scientists all over the world, read texts on the internet or send books with a steamer over the ocean... However, let's assume after the apocalypse there were some groups of survivors who fought each other and concentrated on farming and securing their settlements and education (maybe even literacy) dropped massively in the next generation (because why learn mathemathics if you can use that time to shoot fresh meat or built a secure home for your family). In a world where everyone fights everyone, how could you even think of founding a university until some warlord has become mighty enough to force peace over the whole territory... In that case I tend to compare the post apocalyptic world to countries of the developing world: The rich and powerful are able to afford comfortable living conditions, technology and weapons (and even many people have some access to basic cheap technology while, except for that, living under quite primitive conditions), but the country is not developed or rich enough to produce those things on their own (or there is no interest in the ruling class to invest into the poor's education or living standards). While those upperclass people in our world can buy weapons from industrialized countries, there is no such in the post apocalyptic world and the "hightech" is the stuff that gets scavenged and is sold for a high price. Maybe technology was even destroyed/forbidden for some time in the past - after the apocalypse which might have been a war with highly effective weapons, or a scientific accident, maybe some religious fanatics saw the problem in man having too much power and knowledge and demonized and destroyed it... All those things could influence the meaning that scavenging has in society and how profitable it would be - how much will people pay for a dug out machine gun or its ammunition in a world of crossbows and sabors... or think of the collections of ancient Roman art the popes collected during renaissance... However, all those intellectual pastimes are just own ideas/inventions, not based on some theory about human nature or society or technical development. ]
[Question] [ I'm writing a novel about a (small) group of people with extraordinarily long lifespans. Now I am wondering on the psychological aspects of that, which has been a side-topic here and there in similar stories, e.g. in the first Highlander movie and to some extent in Dorian Gray. It is generally handwaved in fiction about Elves and other naturally long-lived races. I'm wondering if there is some research into this in humans. I'm sure that centenarians have sparked the interest of scientists and psychologists have evaluated how it feels to have attended the funeral of everyone you once knew and such things. But so far my research has turned up largely empty. There's a lot of stuff about how and why people live long, but little about the psychology of long life. So, from your intuition to any sources you might have on the topic - what would it do to the mind of a regular human to live to 200 or 300 ? Can we extrapolate from centinarians or would something entirely new happen? --- Update: My long-lived people know and interact with each other, but do not live as a group together. Most importantly, they do not have their own culture or society beyond the level of, say, fans of some obscure TV series would have. Within the scope of daily life, they are largely isolated from others of their kind. [Answer] I don't think you can extrapolate from centenarians. As Jimmy Stewart once said about age, "after 70 it's patch, patch, patch." I don't know anybody that has made it to 100, but several in their 80's and a few in their 90's, but these people were invariably fragile, and most of them were a bit mentally addled as well. Not one of them could run, for example. All had eyesight problems, mobility problems, and most had memory problems. And though I did not know anything of their sex lives, I truly doubt there was anything to know. And due to their physical deterioration, those people were all pretty conscious of their impending demise, and alluded to it more often than young healthy people do. If nothing else, in their preference to review the past and things they lived through, rather than speak of the present or the future (in politics or entertainment or plans of the younger people they know). They know they've lived their lives, basically. A person living to 300 would have to be pretty healthy for most of it, I don't think a story about somebody living 200 years as physically and mentally degenerate as a centenarian, being cared for and living in the past, would be that good. I would presume that their "elderly stage" is no different than anybody else's: 20 or 30 years, and the same for their "childhood" stage. The human brain is not actually fully developed into an adult brain until the age of 24, give or take two years. Make it the same for your long-lifers. Put all the extension into the middle, and scale it: So between the ages of 25 and 275, they are like people between the ages of 25 and 75; and they age proportionately: That would be 250 years versus 50 years; so a factor of five. That would hardly be noticeable at first; at 30 they look and feel like a 26 year old. But by the age of 75 (50 years older for normal people) they look like 30 year olds, and that will stand out. By age 125 they look like 40 year olds, etc; for every 50 years they only seem to age 10. Their psychology, if they know this or figure it out, will change significantly toward a longer view. I'd expect them to invest more time in education, for example, because in the long run it costs them ten times less in terms of life years. If they have children, they are much more likely to become peers with them, they will look and act the same age and won't always be the "older and wiser", a 90 year old kid that looks and feels 31 isn't going to defer to their 110 year old parent that looks and feels 33; they will be far more equal. These people are likely to engage in serial careerism, as well. If they are intelligent, I wouldn't be surprised if many became business types, and professors, and teachers, and lawyers, AND medical doctors, perhaps investors, entrepreneurs and politicians as well. Architects, engineers, astronomers, actors, writers, whatever they feel interested in, unlike us, they can pursue as a full career. I mean MANY of those careers for a single person; because our society is geared to these careers lasting roughly 25-40 years from education to retirement, and these people have about 260 years (20->280) from education to retirement. If they hurry, they can fit in TEN of what we would consider "life-long" careers. Finally, their psychology of lost loves (and perhaps family, if their children are not guaranteed to be long-lived) will have to change as well. For RL centenarians, everybody grows older at the same rate as they do. They lose friends and lovers, even children and grandchildren, but they never experience the reversal of somebody younger than they are, aging to be much older (in appearance) than they are. These long-lifers might form life-long friendships amongst themselves, but amongst normal people are likely to consciously refrain from such commitments. Instead they are likely to "keep moving", making friends within a few years of their apparent age, staying a decade and moving on. I am not talking about any legal or identity ramifications of them not aging, there doesn't even have to be any. I am just talking about the emotional ramifications: When your best friend has aged twenty five years and you have aged only five, the difference is like a modern person having a best friend twenty years older, old enough to be their parent. 40 v. 20, or 50 v. 30. And for the long-lived person, how about the age difference after 50 years; when their friend is retired and in a nursing home, and they have aged from apparent 25 to apparent 35? It's too much, in terms of energy levels, culture, aspirations and plans, love life, life interests, and everything else. It is better to break it off and start over, in a new town, or even a new country. That might be emotionally difficult, but might actually be better for both, to keep friends with aligned interests for their stage of life. For the same reason, I'd expect them to refrain from forming any deep emotional attachments to short-lived friends, i.e. to intentionally shy away form "best-friend" bonds at all, and maintain just co-worker and neighbor types of friends, bonds that can be easily broken with a few "it's been great" and "I'll miss you" and a "bon voyage" party. Get out of their lives without breaking their heart. I'd say the same thing when it comes to dating. Either they need to "come out" to a love interest about their long life, or keep their relationships short, so they don't break hearts and ruin lives. (Assuming they are emotionally normal and care about other people, and aren't sociopaths.) I imagine psychologically, this could be a relatively solitary life. If there are many of these long-lived people, they would self-segregate to form a virtual community for friends and romance. Especially if the trait is heritable; so parents do not risk outliving their children, seeing them grow from infants to decrepit elderly patients and die. I'm not sure but I think if I knew that was almost certain to happen, I would refrain from becoming a parent at all. [Answer] This problem is occasionally touched on in Dr Who. The idea that not only have you been to the funerals of everyone you knew, but you've done it over and over again for centuries. It leads to a disconnection from the rest of society. Everyone you meet is going to die. We know that, but to us it doesn't matter because it's so far ahead in our own personal time lines. When you're living that much longer than everyone else, it's not so far ahead. You're much more conscious of the brief lifespan of those you encounter, even those you've known for decades. Your relationship with "normal" people changes: [![Han is Chewbacca's third dog](https://i.stack.imgur.com/xbfNF.png)](https://i.stack.imgur.com/xbfNF.png) Since you have a group of these people, they're liable to associate primarily with each other rather than with the shortlifers simply as the only people who've been around consistently for the past couple of centuries. They'll also probably get a feeling of superiority over the brief blips of a life that the normal people have once they have effectively socially isolated themselves. [Answer] # Novelty will make the difference We assume no age-related brain deterioration, so a 270 year old has the mental capacity of a normal 70 year old. Physical aging happens at the same pace. Stereotypically, old people become set in their ways, habits, attitudes and viewpoints. Learning new habits tends to be extremely difficult. ## Perception of Family Three hundred years is enough time to see around 10 generations of a family pass by. In a small, isolated farming community this will lead to some interesting insights that sound like "You look just like your great great grandfather when they were your age." Or, "Your voice is just as grating as your 8th great grandmother. Please stop talking." Family may become super important or it may become of no material use. It will depend on the circumstances. ## Time Perception Observe the following: As a person ages, the amount of time that is 'fast' for them increases. We note that toddlers are obsessed with waiting for even a few minutes because minutes are new to them. Conversely, silver haired elders talk about years or decades passing exceptionally easily. Assuming that something doesn't change, then we can expect that a tricentenarian would look at 50 year increments the same that way toddlers would look at a day. This age induced time dilation may be unavoidable since the brain is very good at discarding information that is "The Same", so after lots of sunrises and sunsets, everything will look the same. The counter is to be constantly on the move and constantly simulated with new things in new environments. Human psychology ultimately revolves around survival. Language, social skills, memory, spatial reasoning are all a result of the advantage that they convey to the individual that has them. For an old person, heck, even for a young person who lives in a single environment their whole lives, their brain and body will be finely tuned to that environment. Most human lives across history revolved around the geographic area of their birth and the plot of land they tended for food. Modern life is a relative exception where the place you die can be thousands of miles away from where you were born. (Mass migrations in the pre-modern world are obvious exceptions.) Memory naturally discards older things because they are less useful, especially details. What did you have for dinner five days ago? I don't know either. Unless you get food poisoning, it doesn't matter. ## Individual Differences Initial conditions will matter a great deal. Some people are drawn to novelty and constantly need more of it. Others are the opposite; content with continual sameness. While people do change over their lifetimes, some basic attributes from youth don't change. [Answer] Extrapolating from those who are 100 years old today towards what it would be like to live 200 or 300 years is most likely no more effective than a teenager's understanding of what it means to raise a family. First off, there are plenty of examples in fiction. The Dr. Who series has several examples, each of which has a different approach. The Doctor, of course, has his approach, but he's not the only long lived character. The Face of Bo is another character with a completely different approach. Ashildir is yet another, with a completely different approach. Ashildir is a particularly useful point of departure because she is human, and she points out a fundamental challenge in answering the question. The dominating factor in how your 300 year olds will think is whatever technology or biology lets them live that long. How does the brain age? In the case of Ashildir, she can't keep more than a lifetime of memories, so she has to keep entire rooms full of journals to remind her of lives she lived. It's not hard to imagine other approaches which would yield different results. One of the major biological limits you will run into is the degeneration of the white matter of the brain. The white matter is the inside parts of the brain. They don't do any calculations like the thin layer of grey matter does, but they're chock full of long axons reaching from one part of the brain to another. These axons virtually all formed before birth, and were pruned to their general shape during early infancy. Damage to these axons is rather permanent, forcing your brain to take the long road to transmit information from cell to cell in the grey matter, rather than taking the neurological Autobahn through the middle. Indeed the corpus callosum, the mighty fabric of axons between the hemispheres of the brain, is made of this white matter, and does not readily regenerate when cut. How we view the world after 300 years would be strongly influenced by whether these rules are changed by the process which let us live three times as long. What those changes are is completely up to you and your story. If our 300 year old humans are nestled in a safe womb of connections which support them, nearly anything is possible. However, if these individuals are expected to be reasonably self sufficient, we can expect that their psychology is one which supports making it 300 years or more without dying. They would be very good at avoiding fatal risks, but they would need to continue to find ways to make themselves useful. This would means they are capable of taking small risks in a continuous manner. Such a self-sufficient 300 year old would have a very different approach to learning. Right now, at my point in life, I have a desire to teach people some of the things I have learned. I have a very short period of time with which to do so. A 300 year old would have no problem not only waiting a generation to teach people what they know, but three, four, or even five generations! A standing question to answer would be what their thoughts on death are. As has been mentioned in other answers, there is the Dr. Who mindset that living a long time means watching all your friends die. But there are other mindsets, particularly in Eastern philosophy, where death isn't such a daunting adversary. Given that many philosophies suggest that you can overcome a fear of death in one lifetime, surely someone who has three or four lifetimes can overcome it and do a great deal afterwards. So you may have someone who has overcome everything. Or you may have a character like Lazarus Long from Heinlein's books which has lived long enough to love everyone worth loving, and faces a real existential crisis from this. The only real limit I can think of to answering this question is that whatever answers you choose send a message to your readers. You have to choose what message you want to send, and tailor your long lived races to fit that message. [Answer] First of all, it depends on how many of these people you have and whether or not they interact with each other. This is from my own POV (not entirely based on any study but on examples I've come across and tried to develop myself), but having a group of people with extraordinarily long lives that know each other would have a different impact on their mental development over time than having isolated individuals who only - or mostly - interact with those with shorter lifespans. Assuming they're somewhat isolated, and assuming they have "normal" human brains capable of retaining information the way a normal human brain would, they would probably lead normal lives until the effects of anti-aging started to show. This means you'd have a normal person to start off (I'm assuming their ageing slows down over time and not that they consistently age slower). They'd probably go through your known stages of grieving a few times, adding up to an increasing feeling of misplacement and the pain and confusion that might arise from that. As it's been mentioned before, I think the most likely outcome would be a detachment from either the human world or reality on its own. These people might grow to consider themselves superior entities, unbothered by affairs they'd outlive. They might grow a nihilist mindset, losing interest in life and interaction. They could cope with it and set long term goals for themselves that might seem unattainable or ludicrous for those with shorter lives. Or they could live in cycles. The possibilities are endless and you could think of a few interesting nuances to add. The same way a normal person goes through phases (puberty, mid-life, etc), you could have long lifespan people have personality/lifestyle phases that would last years or decades and would seem permanent to others. You could even limit their brain capacity to only holding certain memories and have them forget huge chunks of their lives, or have mechanisms to select which ones to keep in mind - but I digress. In any case, it's a really interesting theme to dive into :) ]
[Question] [ It's common trend for many stories within the Urban Fantasy genre to feature various mythological pantheons co-existing with one another. For example, [High School DxD](http://tvtropes.org/pmwiki/pmwiki.php/LightNovel/HighSchoolDXD) has a universe where Judeo-Christian demons and angels exist alongside vampires, the Norse Æsir and Vanir, Greco-Roman Olympians, Near-Eastern dragons, Hindu-Buddhist Devas and Shinto Kami. One problem I've always had with this concept it's that every single religion and mythology on Earth has [multiple conflicting accounts](http://tvtropes.org/pmwiki/pmwiki.php/Main/MultipleChoicePast) of how the universe and humanity came into being (e.g the Mesopotamian Enuma Elish is different from the Chinese Sanwu Liji). How would one reconcile the glaring differences that plague these myths? [Answer] Gods exist as a manifestation of human ideas and beliefs,either by our ideas and world view shaping a uncaring,non-sentient, divine mass or by the gods being a destilation of the magic energy released by the people believe. As a consequence gods believe in their own creation myths because their worshipers believe too,but the more time the gods are active the more they are dissociated from the original belief as thei weave true stories. [Answer] Fallability One common theme in early mythologies is that gods, demons and otherworldly beings are not perfect, infallible exemplars of truth and light. Thor is stupid. Neptune dangerously unpredictable. Zeus gets away with cheating on Hera (for a little while at least) multiple times. The gods are all fallible. With that in mind: who’s to say they have the full picture of creation, or even remember it right? Perhaps celestial gatherings all feature a bit of ‘Remember when our Ron stole fire from the temple?’ ‘No, It was that other fellow. What’s his name? Prometheus!’ ‘Oh yes, I remember now. The one with the kidney problems.’ With that in mind multiple pantheons of imperfect gods is perfectly possible, and perhaps even the gods suffer from the same malady we all do: stubbornly sticking to a version of events that suits our way of thinking while excluding all other possibilities. After all, we were made in their image. [Answer] Creation existed in a state of quantum superposition where all the stories were true until the first oh-so-limited human observer caused the waveform to collapse. (Observation by gods doesn’t cause collapse because they are quantum observers capable of seeing all the possibilities at once.) [Answer] So basically the deities could actually be extraterrestrials with technology a few centuries ahead of us. They settle down on Earth and start consolidating local power. After showing off their powers they are immediately deified. The deities then provide them with their own mythos to keep the population subservient. Depending on the level of advancement of your populous, a simple metaphor for creation might be more suitable than factual explanations of complex physics. It is hard enough to teach algebra to students who've already had years of arithmetic, let alone hunter gatherers. Regional metaphors will be more applicable and will spread faster, facilitating your rise to power. Maybe the humans had creation myths already, and the new deities just latched onto it for simplicity? The deities can help build up and task their civilization to harvest crops, build monuments, and conquer neighboring domains. They would avoid direct war against each-other because at that tech level weapons would be capable of sterilizing entire planets. Perhaps they are enjoying playing around with the civilizations of Earth, much like a game of Risk? Flipping the game board and attacking your opponent directly is frowned upon. These deities could be genetically engineered to have pretty much whatever physical form they want. They wouldn't even need to conceal their technology, it would still be viewed as magical. [Answer] # Gods are humans creations Gods don't exist by themselves, they are just mere humans creations from our collectives believes on the metaphysical plane materialized in our world through the astral rift of mana. When a group of several peoples believes in the same thing during some time, their believes resonance on the metaphysic plane. That resonance provokes a chain mana reaction that emulates and personifies our Gods, allowing them to visit our world and complete their sacred task (believed by us). # Our universe is in complete chaos The universe born from an energy sphere of pure chaos (big bang?). This energy represents everything that is, was or will be. It's all the past, the present and the future possibilities at the same time. With this energy, everything exists and doesn't exist, it's like a quantum stuff. Because the universe born from this chaotic-quantum-everything-and-nothing-at-the-same-time-energy-matter-void all the different mythological explanations of how the universe was created could (or should be can?) had happened at the same time, like a paradox or a multiverse of different timelines at the same time. I am not sure if I'm explaining this fine, actually, the universe was created by any kind of weird mythological way that you could think, and that is why all the Gods existed (and also doesn't exist, at the same time). [Answer] Interdimensional Refugees. All of the creation myths are true - in their home universes. Unfortunately an ancient cataclysm ravaged a number of realities. The United Heavens organised a relief mission, and transplanted as many of their followers as they could to a mostly unaffected Earth - the native species (dinosaurs) and their Gods having died out millenia before. This Divine Intervention has been kept secret from humans, who have been left to believe that this is their original Earth (even though it may be larger, less flat, or even not riding on the back of an elephant) - even some of the younger Gods, born since the "Incident", are unaware that this happened. Meanwhile, the Gods keep a watchful eye for any reemergence of the threat that nearly ended them all... Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn [Answer] There are different theories of human evolution, with some people arguing that human races evolved separately in different locations (I'm not claiming I support this). This was discussed most recently in Superior: The Return of Race Science by Angela Saini. Maybe the different pantheons actually created life in different locations? i.e. the Norse gods created life in Norway, the Greek gods created life in Greece? We could also scale this down to a more acceptable form, perhaps naturally evolved proto-humans migrated across the word and were guided/fostered to full humanity by separate groups of gods? [Answer] They can derive from the same platonic forms. All dragonslayers, like st.George, derive from a single, imaterial, transcendent, Dragonslayer Prime. Each specific dragonslayer is a projection of this Dragonslayer Prime into the material, immanant, world, and their differences (and conflict) arise from the differences in projections. ]
[Question] [ So, I've got a planet that's basically a junkyard. It's just one big junkyard. People from various space-faring societies dump all the crap there that they don't want to deal with. Derelict spaceships, obsolete tech, that sort of thing. And because the people doing this are lazy, what they basically do is just haul a big space barge close enough to the planet's gravity well, cut all the garbage loose, push it just over the edge of the well, and let it fall. So my question is, assuming the trash isn't getting permanently trapped in orbit, and assuming both the trajectory and the exact point in space from which the garbage is released are both random, would the places the garbage falls be random too? Would there be an equal distribution over the entire planet's surface, or as the trash collects over thousands of years, would it start to pile up more in some places then others? Would it start to accumulate a whole lot around the equator, but barely any at all near the poles? Would things like mountain ranges or ocean currents influence this at all? Update: Because everyone was asking, the reason there even is a junkyard planet is simply because humans are lazy. Various corporations and space governments figured out that they could just dump a ton of metal on a planet, and after about a hundred years, an eyeblink in space time, desperate folk would move there and begin setting up their own small-scale recycling operations, purifying the metal, lifting it back up out of the gravity well, and selling it to the companies again for a pittance. It takes a while but it's the cheapest and laziest possible way to recycle things on a massive scale. [Answer] [The distribution of impact craters on the Moon is random](http://adsabs.harvard.edu/full/1966MNRAS.132..413F). I believe the same can be said about Mercury, another crater-ridden body in our solar system. They got their craters from asteroids and comets that struck them randomly throughout the ages. If the drop trajectories over your planet are really random, so will be the impact regions. If you still have doubts, a couple hours simulating this on Kerbal Space Program should solve the problem for you in a very practical manner. [Answer] The initial falling is pretty well covered by the other answers, so this will focus on the other question in the OP. > > As the trash collects over thousands of years, would it start to pile up more in some places then others? > > > Many of the processes would apply to trash on Junkyard the same way that they apply to dirt on Earth. Precipitation If you wanted there to be a variety in its distribution, you could add weather that would prevent some trash from making it to the surface, or dissolve trash, creating a climate-like distribution of trash. For example, if your planet had acidic oceans, the patterns of accelerated trash decay would form in the same way that patterns of precipitation form on Earth, with less precipitation corresponding to less disintegration, and thus more trash. The oceans themselves would only contain trash that could survive their acidity. For example, if Junkyard had Earth's geography, trash on the Western side of the Rockies would receive a lot more acid rain than trash on the opposite side, analogous to how California receives a lot more rain than Nevada. Geological Activity If the Junkyard planet is geologically active, subduction zones might swallow up a lot of trash, and the areas where new crust is made would be briefly bare. Also, the way trash reacts to lava could cause areas near volcanos to have unusual concentrations of specific types of trash Weathering from Wind Additionally, if certain latitudes have faster wind than others (comparable to the winds around Antarctica here on Earth), that trash would erode faster (on a very slow time scale, but still), and would have a tendency to settle around the belt instead of inside of it. Glaciers I'm sure there are more creative ways to incorporate glacial erosion, but at the very least, if someone dropped a comet onto the planet, its chunks might move like glaciers, carving out valleys behind them. For processes that wouldn't apply to Earth: Tidal Locking If the planet orbits around a star, you might want to make it tidally locked, causing trash on one side to melt, and causing trash on the other side to accumulate. Additionally, dumpers may prefer one side or the other to avoid the heat of the star, or to get its energy, depending on which side you prefer. [Answer] It sounds like the pattern would indeed be random, if the drop-off process is as haphazard as you suggest. It's just that if the planet is used as often as you suggest, such a random set of flight patterns could get dangerous. You could have ships heading in to make a drop interfering with each other's flight paths. SOME process wold likely emerge, even if it's only getting on the radio and saying "Hey this is the USS Macawber, if we don't hear from anyone in a half hour, we'll be making a drop run around Planet Junkyard". I wouldn't be surprised if some governing body stepped in and set up flight paths, if only to make sure that some of the trash DOESN'T end up in orbit, or missing the planet entirely and causing a flight hazard. [Answer] Maybe, but I don't think it would be "All over the planet". Most of it would fall along the equator, well assuming normal orbits (equatorial orbits). If you were dropping it in random orbits then it would be random. But if you drop in the plane of the planets rotation (again equatorial) then it would be concentrated at the equator. Obviously if your orbit determines where it will de-orbit, unless you dump it with a good amount of velocity. Anyway now that everyone is done splitting hairs about what I said, and I do stress the OP never defined an "orbit". UPDATE (just an idea) I think a better premise then a Junk planet is a graveyard planet. From an energy standpoint it doesn't make much sense to take the effort of flying garbage to a planet and then slowing down and dumping it, when you can just shoot it into the nearest star. A better idea as I said is a graveyard planet, what I mean by that is something like this: [![enter image description here](https://i.stack.imgur.com/eLt3M.jpg)](https://i.stack.imgur.com/eLt3M.jpg) The US military bone yard. For the most part we keep this place pretty clean but a whole planet used for this purpose and it wouldn't be worth the energy to clean it up. The purpose would be for things like military treaties that limit the use or number of certain ships, for example. It could also be used for deprecated/obsolite equipment. Some of this equipment even though obsolete could still be better then some factions have. And then there is always the use as a parts yard, for post production equipment. You know to keep some of the old stuff fit and running you sacrifice some of them for parts. After a few centuries the place would start looking pretty dumpy. And most of this stuff would have been, safe'd by having the engines or fuel removed before being place for long term storage. So it wouldn't be like you could just land there and sneak off with a star destroyer. Besides you could always have the place guarded by some orbital defense satellites and what not. Even if you want to leave the military aspect out of it, I could see a mega corp taking a small, arid and mineral poor planet and using it for this purpose. Basically a giant Scrap/Junk yard. There may be valuable parts that take specialized manufacturing, or dangerous material that needs specialized handling and recycling facilities. So they take the only thing the planet has to offer a somewhat breathable atmosphere and gravity and use that. Being arid its no good for food production, being poor in minerals its no good for mining. The dryness of the place would be good for preventing corrosion etc. Then they import old ships and equipment, cannibalize them and export replacement parts and scrap metals. But in this case, and if you have valuable infrastructure that you don't want destroyed, you probably wont want stuff just falling from orbit randomly over the planet. You might have a corridor that is setup for reviving bulk scrap metals. Stuff that has no salvageable parts as the energy to deorbit it "gently" would not be justified. This could be around the equator (see what I did there). Couple this with prison/slave labor, and I would believe it was possible in some distant future. [Answer] Does it rotate? If so, the trash would be more likely to pile up on the plane of rotation, which for an earthlike setup is the Tropics of Cancer to Capricorn. However, I think you need to think through the whole low orbit thing. If people were being at all careless in their dumping, there would quickly be a sheath of debris orbiting this planet such that it'd be difficult to land there, and it'd be constantly bombarded with impacts. This would be a tough place to live. [Answer] As @ArtisticPhoenix said, it will likely have a bell curve distribution centering on the equator or some other line near the equator. That is because most planets lie in their star's plane of ecliptic and have a spin that corresponds roughly with the plane of the ecliptic. Most stars are on or near the galaxy's plane of the ecliptic and their spin's correspond generally to the galaxy's plane. This isn't 100% but the majority of the ships dumping stuff should come in with a least cost approach near the equator. Even if ships do not come in on an equatorial plane, since the planet is spinning, their trash has a good chance of crossing the equator and will otherwise be distributed around the planet. If you have ships from different stars coming in at different angles and directions, almost all of their dumps will cross the equator. This will make the distribution higher as you approach the equator. ]
[Question] [ How would the fighting population of a race of goblins be different from that of normal humans? Let's name some parameters for these goblins, first: * Small tunnel dwellers: Probably not important to their demographic. Might affect the overall size of their population, though. * Low Sexual Dimorphism: Male goblins and female are so similar, outsiders can barely tell them apart. * High birth rates: Fewer women need to stay at home to have kids, under normal conditions. * Fast Maturation: Goblins grow up faster than humans do. * Unaging: Goblins do not age. * Death of the Weak: The disabled and weak rarely survive long in goblin society. * Violent Populace: Goblins are naturally violent, so most of the population can be recruited. So, from this, we see that goblins have a lot more population to work with for military purposes, and they can more quickly replace their losses. The question is, how might this affect things? [Answer] From what I can scrounge, it seems that France and Germany in the world wars ended up using about a third of their male (fighting age) population. As a rough estimate, that's about 11% of their total population. Of course, that's not counting all the boys and really old men who ended up fighting, including the Hitler youth towards the end of the second world war. So the question is, how would the goblins compare to this? Now, these examples are humans, in a modern industrial nation, which needs workers to keep making the ammo and farming the food for their armies (unless you're like North Korea, and you just stockpile that stuff ahead of time). If they were a barbarian tribe, burning their own fields as part of an oath to win or die, then you'd be able to muster most of your male population. But with these goblins... they have a larger workerbase, too. Let's look into that. # Goblin Demographics Using US population numbers, about 66% of the population are adults of 15 to 64 years, 14% are 65 or older, and about 20% are children of 0 to 14 years. Using Nambia's population, you get 59% adults, 4% of people 65+, and 37% are 0-14. We'll say goblins have 40% kids of 0-14 due to high fatality and birth rates. That'd leave 56% adults, and 4% elderly. Goblins don't grow old, so that's an extra 4% of the population for labour, making it 60%. ### Children We'll say working age starts at 7 for a goblin. That's means half of the 0-14 age bracket is added to their work force (that is an extra 20% of the population). That makes it 80%. So while the USA has 66% of its population of working age, goblins have 80% of theirs of working age. That means for every five American workers, the goblins have six (per capita). ### Replacing Women at Home Something the Germans are often criticized for in the world wars, is not making use of their women in the war effort. Which is silly... the women were doing a lot of the farm work and other jobs necessary to keep a civilization working, the Germans had already exhausted all extra hands. So, even though goblins have twice the available potential recruits, that doesn't necessarily mean twice the army size. Who is going to farm? Who will care for their kids and babies while they're away? Who will have children to replace war losses? If you send out all available adults, you better win that war fast--or your community will be destroyed. You can get around some of this by details like having group homes for children, and wrangling up the infirm and too young goblins to perform various jobs. They won't perform them well, but then do goblins ever perform them well? If half the population must stay at home So, if we assume Germany could not spare one woman to fight (not without a man taking her place at home), we're looking at 13.34% of the goblin population able to fight. On the bright side, the goblins have twice the recruiting pool to pick from, to increase the quality of their troops. That is... if goblins ever do make quality troops. If a Third of Women can Fight Conversely, if you assumed that the Germans could've drafted a third of their working age women to fight, as well as a third of their working age men, then you'd be looking at an army of 26.67% of the goblin population, over a quarter. ## Total War Population So, if pushed to World War extremes, the goblins can probably muster between 13% and 26% of their population, depending on how you handle that last question. In the larger case, that's over twice the amount humans can muster (per capita). And in the smaller case, that's 118% of human troops. But we have another variable we'll want to add to this: ## Cripples But now we need to consider people unable to work or fight due to medical conditions. From what I can find, between 10% and 30% of the working age population is physically or mentally disabled, in modern states and countries. The goblins, having poor medical care, health issues, work-safety issues, ought to have a high percentage (most would only be missing fingers or such, reducing their work efficiency but still letting them work). At the same time, though, goblins disdain their weaker members. So we ought to see a lot less cripples, who end up starving or even being killed. Those disabled goblins who remain are probably tough as nuts and good at an occupation, or are living on the edges of society (virtually dead, to the system). We could even try to calculate how much of the population is effectively lost to minor disabilities. Where, if ten goblins work 10% slower due to lost fingers, that's the same as having one less goblin, in theory. In the end, I'll say goblins have 15% of their working population in cripples. So 80% - 15% = 68%. 68% / 3 = 22.67% War population, or 11.335% if half the population must remain at home. You can adjust the percentage of cripples in their society (Nazi goblins who kill off their cripples, for instance) to get different results. Even up to half the goblin population being crippled, so that only 13% of the population can be brought to war. ## North Korean Method And if they did decide to be like North Korea, and have all the able bodied persons fighting (using stockpiled food and ammunition etc): At 15% cripples, that means a few months with about 68% of their population fighting. Of course, that doesn't take into account things like the local garrison, caretakers for the children, and people needed for other jobs to stop your cities becoming inhabited with wild beasts and mildew. Looking at North Korea, they apparently plan to raise about 30% of their population, relying on stored ammo and food. # Conclusion By my reckoning, the goblins could muster between 26% and 11% of their population. Depending on how many people they want to stay at home, and how many have infirmities. If they decided recruit their farmers and factory workers, relying on stockpiles of ammunition and food to fight, they might muster anything between 68% and 80%. And that compares to an estimated 11% of the population, for industrial humans in a total war scenario. North Korea from what I hear plans to raise almost 30% of its population for war, by using stored food and ammo. NOTE: This is for a World War/Total War situation. For smaller conflicts, armies tend to consist of much smaller percentages of the population. [Answer] # All of them, including the goats and chickens If you've ever been attacked by an angry hen you'll know it's no laughing matter. It's a hard life in the tunnels, they don't venture out into the daylight much but that doesn't stop [murderhobos](https://en.wiktionary.org/wiki/murderhobo) from wandering in in search of treasure and other easy pickings. Goblins are short, nasty, and violent, just like their lives. They live permanently on the edge of survival. Every fight they get into is a fight for survival and everybody fights. They're not known to die of old age because almost always something gets them first. Whether the marauding "adventurers" from the outside or something even more horrible from the deeper darkness of the tunnels they live in. ]
[Question] [ Some background information: in this world there are races that are ageless. Meaning they stop aging at what humans consider age 30. This of course means that both men and women remain fertile, essentially indefinitely. This could mean that your great-great-great-great-grandfather could theoretically have a child with your great-great-great-granddaughter, if you aren't keeping track. # But that raises the question: outside of three to four generations, and anything outside third or fourth cousins, should one keep track of blood relations? I am well aware of inbreeding depression, so naturally siblings and first cousins should be discouraged from producing the next generation. But with so many generations between them, blood relations so distant, is keeping track worth the effort? [Answer] You don't, what you do is take the other option: Pre-marital genetic testing. This is common in several places and groups including Saudi Arabia and anyone with Jewish ancestry. <https://www.geneticliteracyproject.org/2015/03/26/mandatory-pre-marital-genetic-testing-prevents-disease-and-marriages-in-saudi-arabia/> <http://www.jewishgeneticdiseases.org/genetics-and-carrier-screening/> This is assuming your civilisation is at the technological stage where this sort of testing is possible. In a more primitive environment, family is going to be very important to survival. I'd expect to see several generations of a family still living in the same house/compound, making keeping track of family much simpler than in our modern world of individualism. [Answer] Genetically your genetic similarity-by-descent\* halves with each step removed. This applies equally to vertical relationships (i.e. grandparent->parent->child) and horizontal relationships (i.e. sibling->first cousin->second cousin). So you would share the same genetic similarity-by-descent (12.5%) with your great-grandchild as you do with your second cousin. Even the impact of first cousin relationships on rates of congenital defects is small (estimated at [an increase of 1.7-2%](http://www.nature.com/gim/journal/v1/n6/abs/gim1999184a.html)) and so a rule of two generations would probably be sufficient or three if you want to be strict. In practice, I would think the social limits would be more significant in the vertical than the horizontal direction - having a grandparent who you had a relationship with as a child marry your child is likely to be feel uncomfortable to those involved but the genetics are not likely to be harmful. This accords with legal frameworks in the real world which are frequently inconsistent with genetic realities, for example in my country (the UK) it's legal to marry your first cousin but illegal to marry your grandchild and adoptive relations are also counted. --- \similarity-by-descent is the number of genes that are identical because they come from the same ancestor, the true genetic similarity is likely to be much higher because so much our genetic material is shared across the whole species. [Answer] 1. First and foremost, why* are these races ageless? That much implies a mechanism for cell replication notably different from that in H.Sap. 2. Consider the microbiology you're using, and adjust the consanguinity ramifications appropriately. If these people cease to age, is it because their DNA doesn't deteriorate through repeated replication? 3. Overall, I would think that the lack of ageing implies that these races have far fewer errors in their DNA, and a far lower incidence of error over time. Perhaps this cleanliness derives from a less forgiving reproduction process, such that mutations are almost always fatal. 4. As Separatrix pointed out, one would expect these people to have genetic testing. If not, this also suggests that they don't have a reason to worry about their genetic health. Again, reinforcing bad genes isn't a problem for them, eh? Keep firmly in mind that our "cousins" rules for consanguinity is merely a gross heuristic for risk of reinforcing unfavourable alleles. In order to make this a valid question in SF, it seems that you'll need to engineer a background that avoids the above objections: these people do have a problem with reinforcement, but they have yet to develop research into their own reproductive material, despite enjoying incredibly long lives. Is there some other endeavour more important for every last member of the race? That given, we still need the general parameters for the problem: how many chromosomes (or equivalent) do they have? What proportions of undesirable material do they observe? What level of risk is acceptable to them? Once you decide those parameters, just do the math ... or is that the crux of your problem? [Answer] Inbreeding can be beneficial from a social and economic point of view, it strengthens the family bounds and wealth, that's why it is supported in great part of the world today and it had an important role in history. The reason we don't inbreed is because two persons born of the same parents have 25% chance to give birth to a disabled child, and this chance decrease by 50% for every generation distance between two familiars. Me and my father share 50% of genetic code, therefore we will have 25% chance to bear a disabled child. Me and my cousin share 12,5% of genetic code, therefore we will have 6,25% chances to bear a disabled child and so on, the chances will split for every generation. For example the inbreed between a Great-grandfather and a granddaughter results in 3,125% chance to have a child with disabilities. Inbreeding a great-great-great-great-grandfather and a great-great-great-granddaughter has almost 0% chances to result in a child with health problems,technically the same as to mate with someone from the other part of the world that you never met. As every single person ever lived and living on this planet are technically cousins, it is completely useless to keep track of the family tree after 8 generations.... 16 if you want to be really strict and precise but then anyone you meet on the streets could be your 16th grade cousin or closer anyway, probably even the entire city. ]
[Question] [ What's happening: It's the year 2019. Russia announces that they've developed a few 245-megaton atomic missiles and threaten to detonate one on in the USA. The American president dictator, Donald Trump, orders the red alert and starts compulsory military training to "make America big again". The Interior Minister set up the NPP --Nuclear Protection Program, which basically gives supplies to people-- in case of a nuclear war, and the TNT, Trump's Nuclear training, which threesome soldiers and hired scientists to develop long-range nuclear missiles... I, as a wealthy person (I will invest how much will be needed), can prepare myself for this. I decided, with my family and some friends, altogether like 30 people, to make an underwater base. Since we're not the best engineers (but a friend is a programmer), we don't really know how to construct the base. The base should be: * on a geologically stable place (no earthquakes, volcanoes, etc.) * as deep as possible (bonus for outside light) * far from any shore * not visible (including it's products) from the surface * usable for at least a few decades The base should have: * protection against radioactive waves * protection as well as weapons if somebody attacked the base * a source of food - including all the minerals, vitamins and what not needed * a source of water * a source of air (oxygen at least) * heating * a stable source of electric power * fun - (video)games, toys for the kids, maybe even a copy of the Stackexchange sites - so the people inside don't hang themselves out of loneliness/claustrophobia/fear/paranoia/boredom And of course, the people inside should have a way of fixing stuff that break, and should have total control over the base. Is this even possible? Do these requirements make sense? How can all these requirements be accomplished and where should we make the base? If we forgot something, please inform us. [Answer] TL/DR - Probably not to all of your specifications There's too many variables here that conflict against each other. So let's see what is possible with what we've got. Firstly: Geologically Stable - This is tricky. Oceans are constantly hotbeds for geological activity of some kind or another (underwater volcanism and earthquakes come to mind) A good candidate for a start might be the Polar Ice Caps though, but nowhere near the Pacific "Ring of Fire". Secondly: Depth - As EveryBitHelps pointed out, natural outside light doesn't penetrate far into the water and if you want a full-colour spectrum, you're limited to depths no greater than 20 meters deep, anything beyond this and you start losing Red light. Thirdly: Distance from Shore - With such a limitation on depth you can't get any great distances from a shoreline before the water drops far too deep for this to work, so my suggestion of being in the Ice-caps (Specifically the Antarctic works here) it's far enough away from civilization as to not be disturbed by passing traffic or nuclear warheads. Fourthly: Visibility - Again, the same as the third point is in play here, only this time you have some help from the Antarctic surroundings, as it is so remote and rarely visited, it would be easy to set up a camouflaged entrance to your underwater base in one of the ice sheets. Lastly: Usability - Actually, this is the easiest as the Antarctic already hosts scientists in our timeline for months on end. Your Restrictions: * Radioactively protected - This one's a piece of cake! Water is actually a very good shield against radioactivity on the surface. [There's an image that details this](https://what-if.xkcd.com/imgs/a/29/pool_safe.png), but for the life of me I can't find it at the moment. * Protected vs weapons - The ice makes a good shield here. It's thick enough to sustain a good protection against any attack and its distance and isolation from most inhabited lands make it difficult and nigh-impractical to attack at all. (plus for 6 months, it's very dark and freezing cold) * Food - Food can be grown in biospheres (similar to our current greenhouses but underwater. They already exist currently in space stations and would be easy to set up with artificial lighting as well. * Water - Water can either be used from the surrounding ice pack (as Ice it has very low, if any salt content) or desalinated from the surrounding Arctic (or antarctic) oceans * Air - If there are entrances into the base from the surface of the ice sheets, then you could also incorporate some air intakes, this, coupled with air scrubbers will ensure that your colonists won't suffocate, plus plants also need this to grow so the Food part also requires this. EDIT: Fayth85 had a good comment about Air that I thought would be worth mentioning: > > Actually oxygen is far simpler than you explain here. All you need to do is extract it from water like they do in military grade submarines. Other than that, I agree with every point. +1 – Fayth85 22 mins ago > > > * Heating - This is probably the most difficult of all, being up in the Arctic regions, but geothermal vents or perhaps some kind of steam turbine could work in such an environment, especially in the cold winter months. * Fun - fun would have to be brought with from the outside, but it's not impossible to set up a satellite link that would provide internet for the denizens of your underwater base as well as telephone capabilities should you need to call someone Other factors to consider: Being underwater means dealing with water pressure and that leads to requiring pressurized metal tubes, the difficulty here being that any leak is a potential disaster, so to negate this, you either need to be able to have thick enough metal to support the pressure or a team of people who are capable divers who can repair the base from outside (Required: Dry SCUBA suits, air, etc.) [Answer] Is that base feasible ? I'll say probably yes, but your requirements are quite hard to deal with. First you state you need a stable area to place it. That's not that much hard to find, you just need to avoid as much as possible regions of the worlds were tectonic plate overleaps. Since there are not billions of them you just need to avoid the areas marked on such map : <https://upload.wikimedia.org/wikipedia/commons/8/8a/Plates_tect2_en.svg> It does really limit the area where you'll be able to build your base, but you'll be happy to not have to face volcanoes and earthquakes. Though there'll still be a risk, but earthquakes and volcanoes are less likely to be far away from these areas. Then you need it to be deep inside the seas but with sunlight anyway. As stated in the comments, water stops light after some meters, thus it'll be hard to have natural light if you want your base to be deeply under the seas. What could probably be done would be to place your base under the seas, and use a system of mirrors, or a stuff like that, linked to the base, providing lights from outside, inside your base. It would be a kind of lightwell running over a few hundred meters. Don't know how much light you could bring on like that, probably not much if your well is not located right at the surface of the sea. Then you want your base to be far from any shore. If you can bring sunlight with a well that's not a real problem, you can find quite a lot of place in the ocean hundreds of kilometers away from inhabited islands. The main problem would be in such places your base would be located very deeply under the seas. You also want it to be not visible from the surface ? I have a very good news for you. Modern nuclear submarines are known to be almost impossible to detect while submerged these days, they are almost noiseless, and sonar can't detect these easily (don't remember if this is due to some kind of material or just because of the said "noiselessness"). So you'll probably need your base to be build with some of these special materials used by armies and navies to build stealth tanks/planes/ships, but that's something that exists in our current state of technology. After that you want a protection against radiation. You already got one just by having your base under water. Water operates as an excellent shielding against any sort of radiations.According to that article : <https://space.stackexchange.com/questions/1336/what-thickness-depth-of-water-would-be-required-to-provide-radiation-shielding-i> only 2 meters of water are required for a good protection, your base would most likely have a few hundreds of meters to protect it. That's far enough. Though if you ask a protection to survive a direct hit from a nuclear weapon I think you don't need it : your base is stealth, so you'd probably only be hit by chance. Thus you can't do much about it. Next point, you think your base needs weapons and stuff like that. Well you could have torpedoes to fight underwater, and some guns inside the base in case of a boarding, but to put it clearly, who would ever be in a position to assault such base ? Most likely elite commandos from a random armies, and military submarines/nuclear submarines. In such case, your few civilians friends and your are just screwed. You will never be able to fit enough weapons in a single base manned by a few people to protect against an army. Anyway should I protect that base I'll probably use an anti submarine net, somekind of big net that was used from time to time to deny the access to a port to ships and submarines. So that any opponent would have a hard time coming close enough to fire or board the station. Probably combined with proximity detection mines. But all of this is quite expensive. And dangerous by the way. You now need a source of food, water and oxygen ? Well for food you could still make things grow inside your base, such as vegetables with artificial (or natural) lighting. You could also farm seafood. For water you could just use the sea water, for that you just need to treat it to remove its salt and any other unpleasant things. Most likely by boiling the water of and then cooling down that steam to get water without salt. Such facilities already exists, and works with solar energy. Once more that's something that can be done in 2016. As for the air I don't know exactly the process, but nuclear submarines can stay months long underwater by recycling their oxygen, and space stations/shuttles can do the same, so you just need the same system and a massive quantity of energy. To heat your base, two options, you count on electricity and your main energy reserve, or you could perhaps your geothermal energy ? For this, being not too far away from a volcano could be a nice idea, you'd have a very good, reusable source of heating, the same one already used to supply some server farms in northern countries (Sweden if I remember correctly). It would also solve your problem of electricity, but if I may, using a nuclear plant would help too, generates more power for a long time. Better yet if you can find a fusion reactor then you could have an almost infinite source of energy, by using hydrogen, that can be found by breaking down water into O² and hydrogen. Last point, you need fun, video games and stuff like that ? There are big underwater cables running through the oceans and providing internet. You could just do a little junction to one of these with your base, and with a little of hack get free internet without anyone being able to detect where you are. I hope my answer will help you ! [Answer] If you want to survive a nuclear strike then you don't need nearly this level of prevention. Nuclear warheads are almost always dropped on major cities because thats where they do most damage. What you want is a house that is ... * at a large distance from a city * sturdy, with thick stone or concrete (also acts as radiation shielding) * no drafts (all air goes through air con system) * basement with supplies of food, water, air filters * batteries, solar panels, generator, hydroelectric for power * water filter, near stream? * fallout protection suit and Geiger counter With all or even most of these you will likely survive with no serious harm. (sense also required) It might not stand a direct strike but no missile commander is going to attack a house that is miles from anywhere. [Answer] Go and sink a nuclear submarine (preferably Russian Typhoon class) in that location. And your permanent base is ready... 14°28'20.91"S 135°24'34.53"W ]
[Question] [ The world I am building has two highly intelligent, sapient species coexisting (along with a large number of non-sapient species). One evolved from ape-like creatures and is suspiciously similar to modern-day humans. The other evolved from group-living carnivores. Both have similar levels of intelligence, approximately that of a human. It's the carnivorous one I am interested in here. Never mind all the discussions about how two intelligent, sapient species will have trouble co-existing. For the purposes of this question, let's just say the two species get along just fine (different niches, different habitats, long established mutually beneficial coexistence of some kind; whatever floats the boat in your cup of tea). The carnivorous creatures obviously have to have at least one language all of their own. In this case, their language has a quirk compared to human language. Their language is completely devoid of idioms. If one of them told another to pull its own weight, the latter individual would do something seemingly nonsensical but perfectly literal like rig up a pulley and rope, or grab a sled and some weights. How can I explain that an intelligent species would develop a natural language that is completely literal? [Answer] No language is completely literal, and the very idea of concepts depends on it. When I refer to Michael Kjörling, I refer to a mapping metaphor, or an abstraction, since the real Michael Kjörling (♦) is an ever-changing collection of atoms and energy states organized in a meta-stable pattern, and thus different from millisecond to millisecond. Referring to Michael Kjörling (♦!!) by referring to the indices and Heisenberg-adjusted positions of all particles that comprise their body would be somewhat unwieldy in everyday conversation, and the abstraction of a continuing entity makes low-bandwidth lossy communication about that meta-stable pattern possible. Since we can only do lossy, low-bandwidth communication, that's a good thing (c). Same applies to rivers, trees, prey, etc. However, the species could have an aversion to unnecessary abstraction. English would be a pleasure to learn for ESL people were it not for the tens of thousands of blasted idioms. Could use a dose of no-nonsense carnivorous idiom-purging. [Answer] I don't think you need to explain it. It could as easily be a cultural thing as anything else. Languages enforce all sorts of things (word order, sounds, letter combinations, phonetics) for no particular reason. If you do want to explain it then just make them more literal and regimented thinkers. The language is structured around that and has a very rigid and simple grammar. Complex and abstract thought is not well supported by the language and would not be accepted culturally if people experimented with it. One possible explanation might be if they are pack carnivores with a rigid pack hierarchy, the leader speaks and others obey. There is unlikely to be a tradition of story-telling for entertainment. Stories would be factual and straightforwards reports of events. Music and dancing could expand to take some of the entertainment properties of storytelling but songs would be unusual or strictly factual. For example you might chant a description of how you won the last battle as you marched, they might sing as they go into battle their intent to destroy the enemy, but even that would be limited without access to metaphor and hyperbole. [Answer] Maybe the language is like a legal or treaty language spoken with outsiders. It must be precise, they will not know you well enough to grasp cuktural idioms, and it will be referred back to someone else much later in time. Maybe they don't have what we would recognise as a language within a clan because communication is much tighter and innate. The language you mention is meant for the difficult non-innate communication with "other". [Answer] The trait of linguistic literalism would have to be a part of the carnivore-species mindset. It is common for humans with autism-spectrum-disorders to be literal and pedantic, which is to say that if someone uses the wrong word when speaking to them, they will respond as if the speaker actually meant the word they said, with the result that they will either respond inappropriately (acting on what they were told, rather than what a neurotypical human would have known that the speaker meant), or will question the speaker ("How can I put water in your elephant when you don't own an elephant?" in response to the speaker holding out a glass and asking, "Can you put some water in my elephant, please?", having just seen a drinking elephant on the nearby television). This would be 'just the way the carnivore species evolved'. The most likely explanation would be that when hunting in groups in their prehistory, the prey was also sufficiently intelligent that any individual's mistakes meant that the prey would escape and the pack would go hungry. In such situations, precision of language would become imperative, and there would be no room for ambiguity or nuance. This would carry over into their social lives too. A species with the trait of linguistic literalism might be expected to have no sense of humour when applied to jokes. Humour arises when there is an ambiguity in a phrase that can be parsed in an unexpected way. This is not to say that such a species wouldn't be able to appreciate situational humour, just that you couldn't make them laugh by telling a joke. Bring on the pratfalls... Our linguistically literal species could also be expected to be open and forward when it comes to mating, however they do it. If verbal communication has anything to do with it, they'll just come straight out and express admiration and a desire to mate with the person with whom they are speaking. The response may be positive, neutral or negative, but will be similarly forthright. A side effect of this forthrightness would be that the carnivores would actually be a very calm, unflappable species. Any individuals that had a tendency to become agitated when insulted would be at a distinct evolutionary disadvantage, so we can expect the carnivores to be totally unfazed by insults. They may recognise that they're being insulted, but it would be like water off a duck's back: > > "Oh, the ape is pointing out my faults again. That is very boring." > Yawn. > > > Or, a conversation between two down-and-out carnivores: > > "You are a vaguely attractive female carnivore, I want to mate with > you." > > > "Never, your genitals are diseased and pustulent." > > > "Oh, yes, thank you for bringing that to my attention, I must do > something about that some day. I thought that given that you are not > as attractive as many other females, you might overlook my illness." > > > "I may only be slightly attractive, but I'm not that desperate to be > impregnated that I'd risk catching your pox." > > > "Oh, well, have a nice day." > > > "You have a nice day too." > > > Conversely, the excitable, emotional apes may be continuously nonplussed and outraged by the carnivores' forthrightness and honesty, but given that under normal circumstances, a carnivore could probably casually dismantle a physically obstreperous ape, physical attacks would be suicidal, and verbal counterattacks would be pointless, save as an emotional outlet for the ape. As an example, an ape bumps into a carnivore: > > Ape: "Watch where you're going, you overgrown furball!" > > > Carnivore: "I was watching my path, while you were inattentive > since you were preoccupied in your observation of that female ape with > the large mammary glands, and struck me. For your information, I am > of average size and my fur is of average length." > > > A: "Go climb a tree, you bloody stupid kitty-cat!" > > > C: "The trees hereabouts would not support my weight, and my task today > precludes my taking the time to make the attempt. Perhaps you need to > attend a zoology class, since you seem incapable of distinguishing > between a member of my species and a domestic cat. Additionally, my > fur is clean and my intellect is equivalent to your own, these being > points that a zoology class would also clarify for you." > > > A: "Oh, get your worthless carcase outta my way! You make me wanna > puke!" > > > C: "I do not have any food with me, let alone any of no value, so how can > there be valueless food obstructing your path? Please tell me, how am > I inducing the desire to vomit in you, so that I can attempt to > mitigate the effect?" > > > A: "I'm gonna bust your chops for ya, pal, if you don't get outta my > way!" > > > C: "I have told you that I do not have any food here. How could you > break that which I am not carrying? Additionally, I am not your friend." > > > A: "Aagh! Get outta my way or I'll punch your teeth in!" > > > C, Moving aside: "There is no need to become agitated. Please refrain > from physical violence, since if you attack me, my defensive actions > will most likely leave you severely injured." > > > A: "Oh, piss off!" Begins to leave. > > > C: "Urination in this location is contrary to customarily accepted social > conventions, sir!" > > > A: "Stuff you, you..." The ape's language devolves into profanity > unsuitable for a public forum such as WB.SE. > > > C: "Please moderate your profanity lest you receive a citation for > breach of your species' regulations concerning such utterances. I > observe a law-enforcement officer approaching his auditory range of > you." > > > [Answer] Some of those on the autism spectrum have trouble with understanding idioms and naturally do not use them themselves. The carnivores could easily borrow some aspberger traits and be fully functional as a society. It gets easier when society is organised for that kind of mind. I'm no writer, but I imagine that all kinds of interesting portrayals of society could flow from an "aspberger species" premise [Answer] When errors and mistakes are costly. More than a "technical language", nowadays there is a technical "register" (way of use) languages. If you go to a medical conference, or read an scientific article, each word there will have be read and reread until it is sure enough that it will not induce the readers to error. This is one of the things that makes scientific or technical language so "boring". We were told that if we were writting an article and did need to mention "the INTRO key", each time we needed to refer to it we would have to spell it. Not "that key" or "the same key than above" or "the key with broken arrow". "The INTRO key". If we needed to use the expression a hundred times, so let it be. Why is that? Because we are to avoid confusion with to the audience. Someone reading our article or listening our conference should (with the required experience) be able to reproduce our actions to see if they get the same results. That is why technical language (specially Medicine) have so much words. To you the surgeon may have done a cut in your lower back to heal a bone; your surgeon will write in your history that he did a incission in the intervertebral space (vertebrae L3-L4) to reduce a protussion in the distal-cenital area of L4. So, maybe you may put your species in a habitat that requires close and precise collaboration for them to avoid extinction (or at least at lot of pain). Note that not everything are advantages: such a language would be slow to use, would be less than useful in unexpected/unknown environments and would evolve very slowly. [Answer] Ideas: They have a secret second language or mode which is never used with outsiders present. This may be linked to maintaining a stable relationship to a second intelligent species. There are human societies where it is almost taboo to express particular modes of thought outside of particular social contexts. They have a language with a large vocabulary augmented by a large range of subtle modifiers and an unusually rapid acceptance of neologisms. The combination means that there is always a right word existing or coined when the need is manifest, so idioms do not exist. The subtle modifiers may be extremely difficult for an outsider to master or they may be a secret. Some might be nonverbal. Without them mutual comprehension is still possible but the outsiders think that the language is far more literal and crude than it really is. I do not speak Chinese (meaning any of a large family of related languages and dialects). I was told that because of the tonal nature of the language, every single word is a stack of possible puns: the same sound in different tones. Therefore it is almost impossible to talk without indulging in all sorts of subtle wordplay that will be missed if it is not your mother tongue. Anyone Chinese care to comment? [Answer] ## Combat While carnivores can be social, they tend to also be highly territorial. This could lead to steady levels of border combat especially involving roaming adolescents, as with lions. There's no space for idiom and hyperbole in combat situations. Everything has to be literal for risk of responding inappropriately. Information has to be passed accurately and clearly. Running back screaming "There're thousands of them!" when there were merely dozens would mean that a response suitable to thousands could be given. For a tribe under pressure this would mean critical resources pulled away from other tasks, leaving other borders unguarded or food not hunted (and the boy who cried wolf would be given such a thrashing). Since flowery use of language would be a disadvantage to the tribe, idiom wouldn't develop. [Answer] Where the ratio of communication with strangers compared with communication with friends is much more strongly weighted towards strangers than in our world. Idioms develop through frequent use among people likely to understand them. If you take that out of the picture (or strongly diminish it) and make communications much rarer and put more weight on the consequences of those communications, then you have a situation where people are careful with their words and they don't develop idiomatic patterns of speech (which would include non-literal expressions). So you'd be looking at a fairly solitary species; disinclined to keep a constant peer group. Perhaps nomadic on an individual basis rather than a group basis. The implications of that, though, are fairly large because peer groups and socialisation have tangible benefits which would need to be addressed. ]
[Question] [ Basically, our protagonist wants to get revenge on an evil warlord and his minions (not [the cute kind](https://en.wikipedia.org/wiki/Minions_%28film%29)) for the destruction and butchery of his home village and all those who he loves. He decides to "get biblical on their... I mean them" and begins to plot a plague. He currently lives near a massive pond where millions (\read lots) of frogs dwell. He is very smart, but the general tech level is very low (so please no DNA splicing, or magic). I believe that numbers and chaos will be key. The Protaganist is a Blacksmiths apprentice (almost one in his own right). He has access to a top-of-the-line smithy. He has access to a massive storehouse of raw metals. He is very quick with his fingers and specializes in making small, yet useful metal objects. He has been planning his revenge for a long time and has a secret cave where he stores his stuff. He loves playing with animals, especially frogs, but not as much as he hates the evil warlord. What can he do to his army of frogs to weaponize them? [Answer] New Answer: Frogs have so many disadvantages as a weapon system. They are tiny, fragile and retiring thus making them useful only for indirect, sneaky, nasty attacks. Frogs can't even reliably climb stairs. Poison is the only equalizer here since direct physical trauma isn't possible with this weapons delivery system. Whatever chemical weapon the frogs deliver must either kill the minion outright or cause him to kill himself or attack another minion and kill them. Personally, getting the minion to kill himself or one of his friends is the most satisfying, so let's go with hallucinogens. Anyone who's unprepared for a hallucinogenic high is really going to have a hard time. Their superstitious minds will come up with angels, demons, devils...whatever their world-paradigm offers. Let's assume that there's a frog that produces such a hallucinogen, one that causes visual and auditory hallucinations but also triggers the brains various threat centers. The effects are a mashup between Google's [Deep Dream](https://www.youtube.com/watch?v=oyxSerkkP4o) and Scarecrow's [Fear Spray](https://youtu.be/iqLDCIZ1DIs?t=105). Let's give it a nice long half-life of 18 hours before the effects wear off. The Latest in Frog Gear* Equip each frog with a time delayed sack attached to their back. Let them lose in the barracks, kitchens and in higher places in the fortress. After the time delay kicks off, a tiny hole appears in the sack and the weaponized hallucinogen begins to spread whenever/wherever the frogs hope. If the powder is fine enough, it may be an inhalant or a contact poison (either way, it doesn't matter. The minions won't have any idea what hit them.) Aftermath In a matter of hours, the fortress will tear itself apart as everyone exposed to the hallucinogen temporarily or permanently loses their mind(s). Heck the strain may be so bad they develop second minds and lose those too. Even if the overlord survives (unlikely given how he's an object of fear among the minions), he'll never be able to raise an army again given the terrifying way he lost this one. --- Old Answer: ## Poison the water supply Standard survival knowledge says that if you see a dead thing in your water supply, [don't drink from that water supply](http://survivaltopics.com/that-water-is-unsafe-to-drink/). Dead things equals some really really funky stuff. Further, the bite of the [monitor lizard](https://en.wikipedia.org/wiki/Monitor_lizard) is not in itself lethal, rather the infection that comes from that bite causes massive [sepsis](http://www.mayoclinic.org/diseases-conditions/sepsis/basics/definition/con-20031900) and then death. Contaminating the water supply will lead to sickness or death for a significant portion of the fortress. ## How you gonna do it? Collect a few hundred frogs, (doesn't matter what kind) then kill them. (Exactly how many frogs you need will depend on the size of the stream feeding the fortress. Bigger streams will require more frogs. Sorry frogs!) Mangle the bodies a little to increase the surface area. Put that all in a big barrel and toss in some manure and raw pork for good measure. (Raw pork in anaerobic atmosphere may get you the holy grail of poisons, botulinum toxin. It's worth a shot.) Seal the barrel, leave it in the sunshine for a few days so it's nice and ripe. Go up stream of the fortress and take the barrel with you. Transfer the contents of the barrel to several burlap sacks. Build a small dam to make a quiet portion in the stream. Tie each sack to a large rock and heave it into a dammed pond. The juicy mixture in each sack will leak out and contaminate the water. Repeat this procedure several times till the fortress is a puking their guts out or dying. ## You could have used any animal for that Perhaps but as the OP states, there are lots of frogs around. Frogs aren't especially useful as weapons, outside the application of poison frog toxins to arrows or swords. Frogs can't be herded, they have a long growth cycle that must occur in an environment that humans don't especially like and they die really easily. ## Psychological Attacks Disguise yourself as a holy man of some kind. Lower tech levels generally means an increase in superstition so it shouldn't be hard to foist yourself of as a prophet. Start spreading rumors that frogs are a very evil omen and that anyone seen in the company of a frog will soon die. Kill a minion or two in a really gruesome fashion then sprinkle the area with enough frogs to garner attention when the minion is found. Do this a couple more times. Eventually, the other minions will come to associate the appearance of frogs with a horrible death. Sneak into the fortress and spread a few hundred frogs around. The place will go nuts! Panic like that may offer lots of opportunities for throat slitting. [Answer] They [just discovered](http://www.independent.co.uk/news/science/venomous-frogs-that-headbutt-poison-into-potential-predators-discovered-by-scientists-10444144.html) some frogs which have spikes in their head and actually headbutt to inject highly venemous poison into potential predators. If these were the frogs living in the pond, he could take all their food and make trail of it leading to the warlords castle. He could do this by putting it all in a wagon, cutting a hole in the container and driving it to the castle, maybe crashing it through the gates. The frogs would then (maybe) follow the trail to the castle the next night and infest the food supplies and everything else. Trying to remove them would result in being poisoned. This idea is pretty far fetched but thought it might be an interesting alternative! If not just to consider how different traits of the frogs could affect the method of weaponisation. [Answer] The first thought that comes to mind is poison dart frogs. Another aspect would be if they died the smell would become over whelming. However, the reason the "frogs" were significant in egypt was because they were considered sacred and they couldn't kill them. Whats sort of technology levels are we working with? is this modern tech? 145th century etc? Magic available. If so why not enchant the frogs with spells or make them self destruct like a hopping grendade. [Answer] Poison seems to be your best option. Your protagonist can make poison arrows and snipe the minions one by one. He could also use live frogs, for example by introducing hallucinogenic frogs in his enemies water or food supply, and then use the confusion generated by the hallucinating minions to infiltrate the camp and kill the warlord. I don't know much about frogs but I think the most poisonous ones live in tropical climates/forest. But it's not a problem if you can imagine your own species. [Answer] Although there may be no magic in your world, if people are superstitious enough, he can play on their fears and demoralise his enemies (or cause them to defect) by discovering how to breed lots of frogs. Most tadpoles are predated before reaching maturity, so it may be possible to grow lots by keeping them in a protected environment (there could be problems with cannibalism though). He can then release them secretly and play upon an existing prophecy or claim some sort of divine curse. [Answer] Drain the lake the frogs live in (preferably in the direction of the enemy). The combination of a massive flood and a few million poisonous frogs looking for new homes in their wells/ponds should cause the enemy a few problems. > > No society is more than three meals away from revolution. (Or drinks) > > > ]
[Question] [ I started a lot more SF stories than I ever completed. The fortnightly challenge topic reminds me of an idea I had around 1986 or so, when the new PC's I was selling featured 640 kilobytes on the motherboard (no expansion card needed), and a Macintosh had a tiny B&W screen and a hard-shell floppy disk that held 800K. So I no longer have a copy of my treatment and notes, just some recolections. It occurred to me that many SF stories concerned alien technology, but how about alien magic? As a hard SF story, the magic turned out to be a hoax, but magic and horror are anthopomorphic with rules, as I've noted here, that are more like primate social instincts than with low-level phenomena that we have come to understand about physics. So, consider an alien that is not a primate. This species is aquatic, more beaver than porpoise. It walks on land and has developed technology starting with fire and eventually interstellar travel. But it is at home and moves gracefully in the water. Their primitive cities were built in shallow seas, submerged for protection and climate stability, but filled with air. They sleep in air, but prefer to move in water. The rise of civilisation has brought them more into a terrestrial environment, but just like we plant lawns to remind us of the savanah, they have an affinity for the sea. In my story, a visiter to Earth is “haunted”, as in a horror story, by events and concepts from his mythology. At least one thing is a creature that we (humans in the near future) would consider a “monster”. Other aspects are sensible (and scary) only within the culture, and bizzare or even silly to us. Specific mythology varies across culture, but common elements exist to make a horror story scary, and the underlying ideas of magic follow some universal psycological concepts. Some of those might be different for an alien, and I'm hoping to find some critically so. What would an aquatic alien species do differently in cultural mythology? What magic concepts might reflect different “anthromorphic” pre-science intuition? [Answer] Things that scare us tend to be things that recently (in evolutionary terms) we had reasons to be scared of. The darkness may hide predators or unseen traps. The cliff edge might be unstable and cause us to fall. The tight space might cause us to get stuck or unable to breathe, etc. Individual people might have more or less reaction to them but there is a genuine reason to fear. To answer this question then you need to look for things that would be scary for an air breathing mammal but not for an aquatic creature, or the other way around. Some examples, scary for aquatic aliens but not for us: * Pressure would probably be comforting for them, the feeling of being out in the air with nothing to hold them down or support them would be both scary and unpleasant. * Light might scare them, if they are deep sea dwellers then light might signal predators. * Being surrounded might be an issue, again depending on their usual habitat. If they normally live in deep water then being trapped, even if it's just with land underneath them, might feel claustrophobic. They can only run away in 5 directions if someone attacks! * If they are used to moving in big shoals then being alone might be incredibly terrifying. * If they use sonar then sound distortion or loud noises that interfere with it might be as disorienting and scary as darkness can be for us. Some examples, scary for us but not for aquatic aliens: * Darkness is common underwater, but we really don't like it. * The feeling of pressure, all that water weighing down on us. * Aliens used to isolation might be surprised by our need for company. Or ones that move in massive shoals might be surprised by our need for privacy. * Heights, the aliens would have no reason at all to be scared of heights. When above water for whatever reason they may intellectually understand that falls are bad but they would have no "gut reaction" instinct telling them so. Basically you need to identify something that is fearsome for one party and not for the other by looking at the difference in the environment. What is unknown or dangerous is scary. [Answer] First, I want to strongly endorse tim B's answer, I'm going to assume you read it already for mine. You asked specifically about mythology. Mythology expands off of our innate fears and concerns, so while identifying those concerns is important that is not the final step to developing a mythology. Let me add some other fears or concerns, much like tim mentioned, which I feel could be an important enough factor to drive a mythology. This is all flow of thought, so forgive me if not perfectly written: 1. Movement. Most fish 'breath' by pushing water past their gills, meaning they must stay in constant motion or suffocate. This can result in a very deeply ingrained need to stay moving at all times. They may associate not moving with death the way we associate darkness (which for us meant predators with better senses about to eat us) with death. They may have euphemisms like "stopped swimming" for death, and "keep on swimming" may be the way the refer to someone who is struggling with something and is just trying to keep from losing control. This would also suggest being kept confined in small places would make them claustrophobic, since the limited ability to swim would be equivalent to taking shallow breaths. As a culture and religion this could translate to a species that puts extra focus on continuing to stay busy and never stopping or giving up. Laziness, and specifically lethargic movement, may be a trait they associate with their villains and other 'bad' people. 2. Alternatively perhaps this species is more like dolphins, breathing with lungs instead of gills; which would explain how they can manage in 'air' like you said in your original question. In this case there is less of a focus on movement, however, know where 'up' is, and how far away it is, would be important to finding air. They would likely be far more comfortable with light above them then below them. Even if a room is fully lit, if the light isn't seeming to come from above they may feel uneasy or uncomfortable. They would likely fear darkness even more then we do, since darkness not only means predators but also that oxygen is too far away to breath. They would likely associate 'up' with good and 'down' with bad, as we do, but to an even more extreme degree. "doesn't know up from down" may be a horrible insult of someones intellect or even ability to survive on their own. Lung power would likely be important for such a species. "check out the lungs on that guy" or "I swear he could go a day between breaths" may be tremendous complements. Their very psychology would likely be tied to their lungs and breaths, if they go long enough between breaths they may grow anxious, afraid, and desperate to move (up), as an adaptation to press those who needed a breath to move towards the surface. Availability of oxygen/air to breath would be a major thought of theirs, dying through lack of oxygen would be a major culture fear. I imagine their boggy men would be creatures that steal their breath or trap them away from air. "took his last breath" may be their euphemism for dying as well. Their super heroes and mythological creatures may be being who can go a long time or forever without breathing. 3. Reproduction: Most water based creatures reproduce via external fertilisation, it's simply an easier approach to evolve. However, external reproduction usually means a system with lots of eggs and a quick spray-and-go approach; in other words a R species. This would have a massive change to their psychology, I already discussed some of the psychological impacts of R vs K reproduction strategies in many other posts of mine. However, it's unlikely for an R species to reach sapience, so they probably won't be using that approach. It's probably best to create a species that uses 'standard' internal fertilisation and has only a few young, as it's a major challenge to create a believable intelligent R strategy species. How they reproduce in general could have a MAJOR factor on their culture and mythos, I would say reproduction is one of the biggest parts of our own early mythologies; but without knowing what avenue of reproduction you choose to go with I can't really go much into how it effects their mythos. Closely related is their sense of beauty. They will likely be focused on sleekness and being aquadynamic, as travelling through water quickly and energy efficiently is a big deal for all aquatic creatures. Speed of movement may also big a big source of attraction to them, analogous to strength as the biggest physical trait humans look for in mates. Their mythical heroes will be sleek and absurdly fast, able to cover large distances quickly. Ability to control their movement in water, change directions quickly, move in all 6 directions, and not get disoriented by many direction changes, would likely be valued heavily as well, how much depends on how they feed and rather speed or finesse is a larger part of catching their prey (or not being caught by bigger fish). Like speed mobility and ability to change directions quickly would be prized in their hero. Physical deformities that lower movement speed or mobility would be considered the worst-they are bad for humans, but we have a particular disgust of non-symmetry that we value as heavily that likely will not be as relevant to aquatic species. 4. water quality would be a huge focus to them. The quality of water and contents of the water would significantly affect them in so many ways that it will be an all-encompassing focus of their mythos. They need to worry about light, but also how murky the water is (both due to viability and because murkiness may suggest contaminants that could harm them). If they have gills the quantity of air in the water will be something they intuitively sense, and less air in the water will always make them uneasy (and anxious to move more as with point 1). The currents of water will affect their movement. Water also is a much better conductor of heat meaning aquatic species will be far more dependent on water temperature since they will be less capable their internal body temperature, even technology like clothing will do less, thus the temperature of the water will be far more important to them then the air temperature is to us. They also care about water quality because it effects how much prey their likely find. We have to worry about many of the factors above as well, but in our case each of them are seen as separate factors. The presence of light, air, disease, and food all depend on the quality of water to them; where as we see all of those as mostly separate, if sometimes related, factors. They will thus have a heavy focus on water quality in all their myths. They will have adjectives to describe feelings and situations based off of water quality. Something feeling 'murky' to them will mean dangerous, uncertain, and hard to survive, as murky water limit ability to find prey but also a more general fear of murkiness being from contaminants that could be dangerous. Their version of Hell will likely be water filled with so much murk and other containment that they can barely see, which clogs their gills, or sticks on their sleek body to slow them and make it hard to move. In other wards an oil spill is their hell (insert BP joke here) They may associate oxygen level with happiness. telling someone to have a oxygen rich water day may be the equivalent of saying they have a happy day. All the places we would use presence of light or darkness to describe a place as happy or sad they would instead use the degree of oxygen in water to describe the same connotations; assuming they use gills of course. Figure water, and its quality, will be a huge factor in all their myths. Pure clear waters will be the perfect place they look for. If they are predatory then the presence of lots of fish will be important too. Magics associated with changing the quality of water around them will likely play a key role in myth. With water being an all-encompassing factor of their life the ability to change it will be huge. Any place with have magic healing or blighting a place in our world it would take the form of changing the water quality in their myths. 5. Water currents. Closely related to the above, the flow and ebb of water currents would likely play a key role in culture and myths. While we have an awareness of the breeze in the air, and even of storms 'blowing in' we are far less aware of the natural flow of air around us; as it plays a less direct effect on our daily life. Water, however, will bring with its tides fish, pollutants, air, new 'smells', pretty much everything. As water quality is an all encompassing factor of their life tides which can change that water quality would be significant. Tides would be associated with change, for better or worse, in their myths. Their terminology would likely replace 'omen' with tides. They may talk of an ill tide flowing in, or wish someone good tides. Notice that they can not keep the water from changing when a tide comes in, so if they wish to stay in one area (rather then traveling with the tides) they will be far more dependent on the tides and what they bring then humans are. We have to worry about the wind bringing storms sure, but those are passing things; we mostly can control our environment more (I'll add another bullet point on this probably). This means that their myths would likely reflect their concerns about the tides changing things, possibly even their inability to affect the tides. In some ways they may see the tides as 'fate'. If someone asks why someone never did something they had wanted they may wistfully say "it wasn't in the tides for me" This would suggest one mythical being/god may be a god of the tides, who is roughly equivalent as the god of fate. He brings good tides to the worthy, and bad tides to the bad. Perhaps he is seen to manipulate people (or other gods) the same way as the tides, by pushing them towards his own goals subtle (remember, tides will generally be slower moving things, not like fast wind, so tides can still be seen as subtle even as they are life changing). In fact I would see a god of tides as likely being one of the greater gods of a pantheon, perhaps with elements of manipulator or trickster, less direct power as the other gods but subtle and far reaching strength by moving the tides that make him still one of the greater gods. The sort of god that pulls strings from the background to make everything happen the way he wants. Going along with the tides, remember they are more complicated then our wind. With 6 dimensions, rather then four, to work with you can have tides pushing and pulling in more complex manners. For various sciencey reason tides would be more complex then the wind (that is close to earth and we experience) seems to be; and the depth one goes will likely play a key effect on the sort of tides you find. This may cause tides to be seen as not just powerful, but a complex and hard to be understood force. They may have 'wise men' who can read the tides, and being able to predict what subtle difference in the tides they will find could by seen as a mystical art. Tides could be associated with magic. In fact magic would likely flow through the water current in many myths. Magic can be cast anywhere, but it propagates out on water the same way a drop of dye would spread out; as they are use to the idea of water spreading everything. Likely magical figures would radiate magic out from them through the water. The ability to 'read the tides' may be required to cast a spell at a distance, because magic users will cast their spell in a tide and wait for the water to carry the magic to the appropriate place. Diving deep (or high, if they live deeper down) to find the right tides may be a common concept in their myths; as it associates wisdom of reading tides with the unknown of swimming to a depth most of their kind is not comfortable in to double the air of unknown mysticism. 6. Senses: Humans relay quite heavily on our sight, but aquatic species won't be as dependent. Really most species are not as dependent on sight as us, we have evolved our sight to be better then the vast majority of species (especially non-flying ones) and have some of the most nuanced sense of color of any species out there; so it's unlikely any species, even non-aquatic, would have quite the focus on sight we do. For aquatic species their sight would be dependent not just on time of day, but on depth from surface and murkiness of water, making dependency on sight potentially limiting. If they are a predatory species that eat fish their eyesight will likely be most developed towards sorting out movement of fish to be able to follow them as you chase them. In other words they would likely be better at distinguishing movement and quick changes, but not as good at looking at a still picture and appreciating nuisances out of it. If they hunt fish that live in groups their ability to not be confused by the groups motion, and instead focus on picking out a single fish from the school, would be a prized ability though. They will likely have other senses that well developed, though how much depends on many factors of how they evolve and what their adapted for. Sound carries over much longer distances in water, but can also be distorted easier. The species would likely not try to use sound to pinpoint exact locations, but they would be evolved to pick up sounds from far away and be better at judging distance of sound and general direction. (note to self, add a communication bullet point below). They would likely have a highly developed sense of taste/smell. I put those two together because the difference between the two is complicated. In a way our sense of smell is nothing more then 'tasting' the air, and the things carried in the air; with aquatic species these 'smells' can travel over further distances and be stronger, but the distinction between smelling them and tasting the water is kind of grey. Similarly they may use this 'taste' of the water to describe things. As they are constantly 'drinking' water they are quite susceptible to pollutants in the water, and will likely have developed specific 'tastes' for a large multitude of potential pollutants, and they would subconsciously avoiding waters that 'taste' bad because that may mean that area is less healthy. Perhaps a place has a 'bitter' taste, which suggests pestilent and wasting away (due to contaminants). Another area may 'taste' like blood, meaning immediate danger, or death. All the ways we could use smell to elicit an emotional response would apply here, but to a much larger degree, since the species would be more evolved to relay on their sense of taste/smell as much as their eyes to measure the world. The 'atmosphere' of most areas could likely be defined by describing in detail its exact taste, with different connotations to each of the many tastes. An area may taste 'wrong' if you want to build up a sense of foreboding, dread, or horror. 7. Communication. The species would likely use clicks like dolphins to communicate, which would spread out over a long area. The ability to stay in contact with people quite a ways away, even without seeing them, would likely play a role in their myths as well. I imagine many myths would have a 'voice' coming from the distance to speak to a certain dolphin, but one that he can not place or which has some unearthly or special sound to it to make it sound more holy/magic. For instance, in their myths instead of God speaking to Moses via a burning bush moses-dolphin may instead simply hear a far off clicking without being able to see who it belonged to (which by itself may not be unusual or mystical to the species). However, the clicks may come to him directly, without sounding distorted or muffled the way sounds are under water, indicating they come from some holy source. Clicks carry a little too well, making it harder to 'whisper' secrets, which is an interesting cultural impact in itself. Perhaps one of their diety-fishes is the fish of secrets, who has the magical ability to keep his clicks from spreading out to others to hear. This may make him seem a little evil or unnatural, having the ability to spread secrets without anyone being able to overhear as is natural. He could be an evil god, or just a trickster deity. Imagine if the fish of secrets was an extremely tiny minnow, small enough to be of little direct threat, but able to travel everywhere and watch everything, known for spying on everyone thanks to his small sizes. He then uses his secrets to talk to far more powerful beings, trading secrets for favors, but also tricking others. Relying not on massive power of most dietys, but his brains and knowledge and 'tricks' to survive despite being tiny and small. 8. size: the size of species in water varies drastically, far more then is possible on land (due to water better 'supporting' their weight aquatic species can reach gargantuan sizes compared to land based cousins). It's likely that our aquatic aliens, if sapient, would be on the larger end of the 'medium sized' fishes; basically dolphin sized (large enough to be strongly K selected, but small enough to still have short enough life cycles to allow evolution to work its magic). They will be use to the idea that the size of creatures around them can vary drastically. Whales that are massively larger then them, to fish smaller then the tiniest minnow. Their myths will likely reflect this idea of variable sizes. Obviously, making a deity that is unfathomably huge is quite possible for these fishes, after all with blue whales already dwarfing your average dolphins it would seem that size is not a limiting factor, so why wouldn't there be deities of unbelievable sizes? it would seem more natural and easy to assume. In fact, it's not unheard of to have gods or other powerful beings that held up the world, like Apollo. With aquatic species likely having some massive sized gods the concept of an Apollo-like god that is so huge he dwarfs the oceans seems a likely superstition. Perhaps their Apollo-fish is said to be huge and all the oceans are carried within his mouth? After all, the really big whales tend to have gigantic mouths, even relative to their size, and often eat very small fish in mass; so our aliens would be use to the idea that the biggest whales usually have tons of tiny fish in their mouth. It's a logical extension to assume that their largest deity is doing the same to them. I think it would be amusing if their version of ragnorak was the whale finally swallowing lol. However, not all gods have to be larger then life. In our myths deities general are portrayed as huge, but that's because large size means lots of physical strength, which we respect; but which is not as important to aquatic species as speed. Plus, having a huge deity in our myth shows they are able to do something no mortal creature can, in aquatic worlds the fact that there seems to be no limit to the size of animals may very well make gigantic larger-then-life deities not feel as special; since it doesn't require godhood to be so huge. Instead their gods will likely run the gambit of sizes, from Apollo-god to the minnow sized secrets-fish I mentioned above. They will likely have far more variety then our own gods. Since speed and dexterity would be valued more then direct might there is less of a need to make gods big to make then impressive; especially if the gods relied on magic or other mystical powers instead of overt strength. Likely the most common god size would be an alien just a little bigger then our aliens in size, but with sleeker build, being longer but not wider for instance; but this won't be as consistent across myths. Magic which changes the size of creatures would likely show up a bit more in their myths then our own, owing to the fact that it seems plausible that huge gambits of sizes are possible, and that shrinking would not necessarily be seen as lessening someone, if they gained speed and dexterity to go along with it. Being able to shrink yourself at will would be a positive ability, and likely would be something a lesser god or demi-god would have as an ability. In fact owing to the much wider range of aquatic species per cubic mile in oceans then on land animals on ground the idea of deities being able to take many varied forms will likely be a little more common, as will the idea of having shape-shifting deities. 9. the vast unknown: Our myths have always had stories about exploring far away places, but our ability to explore was often limited by physical ability to travel, mountains, deep forest, or rivers limiting our travel path. With oceans you can travel seemingly forever in any direction. Their myths would likely involve heroes who traveled unfathomably long distances to far off places. However, in some ways this may remove some of the mystique of traveling so far. Creatures are more uniformly distributed. The same fish you see here your see 20 miles in any compass direction, because the environment will be the same (assuming the aliens don't live near the ground, where reefs and the like can add some more variance). On earth the changing environments of forest and mountain and marshes mean that very different animals can be found in environments that are pretty close together. Likewise when you finally manage to cross to a new area, you climb the mountain or use a boat to cross the river, your likely find different species, geographically cut off from those on the other side of the mountain and thus evolved a little different. All this encourages the idea that exploring new lands on earth will find new and different creatures. Our space-aliens may assume that the exact same fish will always exist no matter how far they travel in any compass direction because they never see a noticeable change if they keep swimming in a single compass direction. However, there is still a way to get mystery, there are two new directions for fish to travel, up and down. The type of fish and species you find when traveling vertically through water changes quite quickly. In addition practical limitations will likely prevent most aliens from swimming too low, or high, from their preferred depth. Thus the extreme deep, and/or the extreme heights if they live in deeper waters, will offer an air of mystery (or should I say tide of mystery). Thus if you want to show off how strong, or fast, or impressive your heroes and mythical creature are have them travel treat distances in the cardinal directions. However, if you want mystery, magic, adventure, or the unknown have them travel up or down. Most mystical things will reside above or below or aliens, not far away from them. ...Okay I could do more, but I think I made my point. I'm going to just stop now before I write a book. ]
[Question] [ A bridge is collapsing, and our poor MC is stuck in the middle. The ground beneath them collapses, but they miraculously are able to climb up the falling debris and safely make it to the main land before the whole bridge is lost. My question is, how fast would one have to move to complete this feat, or one similar, with gravity equal to that on Earth's? [Answer] The important factor here is that human muscles can exert less force as they move faster. [This paper](http://onlinelibrary.wiley.com/store/10.1113/jphysiol.1949.sp004437/asset/tjp19491103-4249.pdf?v=1&t=i8xdzoti&s=41c4a025748cf3e3c158b0c33195f5d8f80f37fe) shows that the elbow flexors are limited to speeds of around 6 m/s. This [other study](http://e.guigon.free.fr/rsc/article/WickiewiczEtAl84.pdf) shows that the maximum velocity of most muscles is pretty similar, so we can assume that the maximum speed of the leg is similar. Since the femur is somewhat longer than the forearm, I'll assume a maximum speed of 7.5 m/s. Remember, at this speed the amount of force the legs can apply is zero. Another important fact is that during a typical jump, the legs apply downward force for [about 0.5 seconds](https://www.youtube.com/watch?v=qN3apht8zRs). Assuming that your character starts crouching on a large piece of rubble (so that the jumping force has negligible effect on the speed of the rubble), at the end of the jump the rubble will have a downward speed of about $$ v = gt \approx 4.9~\text{m}/\text{s} $$ At this point, maximum force is reduced to 15–20%. A fit person can lift around 1.5× their weight in a squat, meaning that the 'isokinetic' (zero-speed) leg extension force is around 2.5× body weight. At the end of the jump the extension force will be reduced to around 0.4× body weight. This means that even in the best-case scenario (starting squatted on a massive piece of rubble) a person cannot even stop themselves from falling, much less propel themselves upward. --- In a more typical case, where your character starts standing, they will not be able to jump at all. When the ground under them starts to fall, both them and the ground accelerate downwards at the same speed. In a frame accelerating with the rubble, the character will appear weightless. When they flex their legs to jump, they will not move downward, but instead their feet will lift off of the ground. This is what happened when the Mythbusters [tested this very scenario](https://www.youtube.com/watch?v=IH4DqLceoAs&t=1m10s). [Answer] The Mythbusters tried this in one episode, and it was totally impossible for them to do (good thing they had a safety harness.) The only realistic way for this to be possible is if the MC is some sort of superhero who can kick the falling debris downwards so fast he is essentially creating a rocket, with the debris as reaction mass. Since the debris is already falling downward at an acceleration of 1 "g" this will mess up the rocket equation (and someone smarter than me will have to do the math), but as a hand wave, if you want to "climb" the falling debris you would have to accelerate it by at least another 2 "g" (you would need 1 "g" just to remain in place and another "g" to accelerate upwards). The downward spray of debris moving at 3 "g" will have a few consequences of its own, and if the debris runs out before the MC reaches the top, then he would somehow have to accelerate the air under his now rapidly spinning feet to make that last distance. [Answer] "Every action has an equal and opposite reaction". You would have to push down with enough force to push you yourself up. Does that sound easy? If it does, remember that that debris is accelerating away from you. Because of this, it is impossible. [Answer] Actually, the speed is not the problem. When your character pushes the falling debris to climb, the debris will fall faster because of the energy of his 'kick'. He won't go up even a bit because he and the debris are in freefall, and there's no normal force in freefall (normal force is basically the thing that pushes you up when you jump). So there's really not an answer to your question, because it is physically impossible, no matter the speed of the character. On the other hand, if your character has some kind of jetpack, he can use it to 'fake' normal force and that way he could climb. But it wouldn't be a real climb, just a powered flight :P More info about the world in which this is happening would be nice :D Some sources: <http://en.wikipedia.org/wiki/Normal_force> <http://www.physicsclassroom.com/class/circles/Lesson-4/Weightlessness-in-Orbit> [Answer] There is no fixed answer to how fast you would have to move: it depends on the speed at which the bridge is failing, both for individual elements tearing free and the transfer of failure to adjecent elements. Imagine if you will: a deck unit groans loudly and then lurches as one steel cable breaks. This transfers force unevenly to the remaining cables so they failin turn. Cables stretch and frey; masonary crumbles around support joints; so the deck unit sinks, shifts, and lurches for a while. It doesn't instantly let go and start falling freely. The characters don't jump from the free-falling block as some answers describe. The OP says they climb. They have some window of time to run and climb onto the adjecent deck unit. How much time? It depends on how fast the failure progresses. For greatest drama, it will fall as soon as the party makes it off, with one fellow left scrambling. And it’s perfectly natural to suppose that moving the people's weight to the next deck unit will cause or potentate the failure of that one next. [Answer] This was a fun question to apply physics to! In short, your character has less than 0.9 seconds to jump up and grab the ledge. After that, they would have to hurry up and pull themselves up and run off the bridge to safety. First, I found how high he/she would have to jump and grab onto a ledge with their fingers. A very good vertical jump is an astonishing 1.27 m. If they're 6 ft., then that gives them 6 ft, plus 2 ft of arms extended above them, plus their jump of 1.27 m. That gives a total distance of $d$ = 3.7 m. Plug into the following equation: $d = v\_{0} t + \frac{1}{2} a t^2$ Using $v\_0$ = 0 m/s, $a$ = 9.8 m/s^2, and $d$ = 3.7 m, then $t$ = 0.87 s. If your character is athletic, and quick to react, then I can see this as plausible. They can also more easily react if they hear the cracks forming so that that gives them an edge in reaction time. Bonus, once he/she is up on the uncollapsed bridge, they would have to sprint the rest of the way. A Google search tells me the average sprinter (keyword athletic sprinter) can run 100 m in 14 seconds. So that's $v$ = 100 m / 14 s = 7.14 m/s. Find out the length of your bridge and use this formula: $d = vt$ to find out his/her distance or time to cross the bridge. Remember to divide the distance by 2 if the bridge collapses in the middle. Cheers! [Answer] No reasonable amount of speed will let you do that movie trick. To jump up, you need to generate upward force with your jump. That requires that you push against something. But the debris is not solid ground, it will not provide you with any resistance to push up against. The only thing you are pushing against, debris or not, is air and maybe, maybe you can generate a tiny amount of force through the inertia of the debris you are pushing against. However, without doing the math I'm quite sure any such gains are instantly eaten up by the air resistance you need to overcome on your way up. ]
[Question] [ In my world, families posses family plates containing the ashes or their predecessors. Is it feasible to have crockery made of human ashes? If so, what properties can I expect from the pottery? What colours and kinds of pottery (stoneware or even porcelain) can be made from the ashes? Bonus: Are there any good resources to read up more on the topic? Edit: If there are any recyclable products, any mention would be appreciated. [Answer] Totally. [Bone China](https://en.wikipedia.org/wiki/Bone_china) is made from bone ashes. The porcelain made from bones is the strongest kind of porcelain. It is also very white and somewhat translucent. [Here](https://en.wikipedia.org/wiki/Bone_ash) is a link to more uses of ashes of bones, in case you are interested. [Answer] Yes. If we're talking about the ashes that would remain after a human body was exposed to kiln temperatures (> 1000°C), then we are talking about the mineral content, i.e. the calcium from bones. Bone is made of calcium phosphate, which is pretty inert for ceramics purposes; it won't melt or undergo chemical reactions in a kiln, so it can't be used to make ceramics on its own (if we were talking about seashells, made from calcium carbonate, it would be a different story). However, bone ash can be incorporated into ceramics as a filler, in the same sense that raisins or nuts can be baked into any kind of cake or bread. But in the same way you can't make a cake from just raisins, you still need to mix bone ash with a significant proportion of clay. It is the silicates in the clay that melt and fuse to create a solid material when the pottery is fired. At these temperatures, the ash will basically be white – the very small amounts of other inorganic elements like iron will not be enough to affect the color noticeably. ]
[Question] [ READ EDITS I am writing a passage about the main character of my book travelling up a space elevator to the spaceport that rests in geostationary orbit above Mars. This means that the elevator would have to travel roughly 17,000 km [previously wrote 20,400 km] from ground to station. I'm trying to figure out how fast to make the elevator car travel in order to determine how long it will take, but my math is concerning me so I thought I would turn to you my fellow worldbuilders for help. I am having trouble finding information on the maximum G-forces a person can stand comfortably. I need this so that I know my maximum acceleration. So first question: What is the maximum G-forces someone can stand COMFORTABLY? I use the term "comfortably" loosely, as I mainly mean tolerable for long periods of time. What I did find is that maglev trains accelerate up to about 0.5 Gs (I am imagining a sort of maglev elevator). This means that if I am remember my kinematic equations correctly, (and not fudging it up because its almost 1 AM here and I'm tired) I should be able to make the trip in about 110 hours with a continuous acceleration to halfway and then deceleration the rest of the way. Meaning I would make the trip in roughly 4.5 days, which isn't ideal. I would appreciate if someone could check my math, although it might be correct since I did find an article stating the same thing on Earth might take around 7.5 days. Is it reasonable to assume this is the fastest method of space elevator travel? I'm open to suggestions on design changes, but would like to clarify that there is no artificial gravity tech. Further background for clarification: This is suppose to take place roughly 400 years from now, however technology has probably only advanced 100-150 years give or take due to the destruction of Earth around 2100 AD, leaving Mars as the new center of human life. Computer science slowed with the end of Moore's law, but jumped up again with early quantum computing. Medical science has advanced to counteract most of the negative affects of living in low G through strict exercise regiments and medication to promote bone and muscle development. Materials science has made a few leaps to allow for the issues with maximum speed or just building a space elevator in the first place. Edit: Previously had written Mars geostationary orbit as 20,400 km instead of 17,000 km. The reason for confusion is that the previous number was the distance from Mars' center of mass, not the Martian surface. That said, my calculations were definitely wrong since they used the first number. Edit: My calculations were way off because I forgot to convert 0.5 G back to 4.9 m/s^2, so I just used 0.5 and got way wrong numbers. [Answer] TL:DR: 62 minutes, shorter than that, or "it depends, but longer" are are possible answers. ## An Hour Okay, it looks like [from this question here](https://space.stackexchange.com/questions/6154/maximum-survivable-long-term-g-forces), that 4.9m/s2 of additional acceleration caused no major problems for seven days. So we should be fine at a half-gee. Great. We can do this. Now, how long will it take? Assuming we've got a maglev with a theoretically unlimited speed, how long will it take to get up there? $$ 8\,500\,000 \text{ m} = \frac{4.9 \text{ m/s}^2 \* t^2}{2} $$ Well, given an acceleration of 4.9m/s2, it will take 1863 seconds (31 minutes) to get up to the halfway point, at which point it will be moving at almost 10 kilometers per second. Slowing down will take an equal amount of time and distance, so a bit over an hour. ## ... is the slow time But wait, that's the simplified explanation. See, the strength of Mars's gravity is decreasing, while the centripetal effect on the train is increasing. So you can start accelerating even faster. While accelerating up (start of upward trip, end of downward trip,) we accelerate at rate a: $$ a = 8.6 \text{ m/s}^2 - \frac{GM}{r^2} + \omega^2r $$ And while accelerating down (end of upward trip, start of downward trip,) we accelerate at rate a: $$ a = 8.6 \text{ m/s}^2 + \frac{GM}{r^2} - \omega^2r $$ Where G is the universal gravitational constant, M is the mass of Mars, r is the distance to Mars's center, and ω is Mars's rotational speed, in radians per second. The first term is the "gravity" the passengers will feel. The second term is Mars's gravity. The third term is the centripetal effect on the rail. Now figuring out how to use those equations to get actual answers (total travel time, time until flip (it isn't halfway,) top speed) is going to require knowing how to handle differential equations, so... you can just stick with the 62 minute answer if you want. ## Hang on a second This is, of course, assuming that your maglev has an unlimited top speed. If it doesn't, then that becomes the limiting factor. The "multiple days to get to GEO is based off a climber going at ~80 meters per second, based off the speed of the fastest trains. at that speed, it takes about ~60 hours to travel 17,000 km. A Maglev is actually a good idea for this, since it won't run into the problem of wheels exploding when you try to spin them up to 10km/s. Still, there will be technical problems with trying to get a maglev to work at those speeds. Not unsolvable, but still something to keep in mind. Even if you could get a maglev to go that fast, people might not consider it safe, and limit it to slower speeds. [Answer] A discussion of climbers or the vehicles travelling up and down space elevators proposed the following limits factors for the speed of a climber. > > Climber speed would be limited by the Coriolis force, available power, and by the need to ensure the climber's accelerating force does not break the cable. Climbers would also need to maintain a minimum average speed in order to move material up and down economically and expeditiously.[citation needed] At the speed of a very fast car or train of 300 km/h (190 mph) it will take about 5 days to climb to geosynchronous orbit. > > > Source: [Space elevator](https://en.wikipedia.org/wiki/Space_elevator) The five days cited above applies to a space elevator for planet Earth. However, this paper by L M Weinstein, NASA, has an estimate for an ascent on a Martian space elevator (where the space elevator is connected to the moon Phobos as part of the system). > > As the > payload is moved higher above Mars, it tries to move laterally from the elevator, since it is moving to an altitude > with a different rotational velocity. However, since the payload is attached to the elevator, it gains orbital velocity by > the constraining side force imposed by the tether itself. Lifting a payload from Mars to Phobos at an average speed > of 133 km/hr (arbitrarily selected reasonable speed) would take about two days, so the side force can be considered a > very weak acceleration continuously applied over that long time. The side force on the elevator would only be about > 5 N for a 500-kg load, and would be easily constrained. > > > This [paper](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030065879.pdf) above gives an answer of two days to travel a Martian space elevator. REFERENCE: 2003: Space Colonization Using Space-Elevators from Phobos, by Leonard M. Weinstein, NASA Langley Research Center. 9 pages. Author: Leonard M. Weinstein Advanced Measurement and Diagnostics Branch, NASA Langley Research Center, Hampton, VA 23681, USA E-mail: [[email protected]](/cdn-cgi/l/email-protection) [Answer] Your idea to compare to Maglevs is smart, but you have a problem with timescales. Those trains only take a minute or so to get up to top speed, at which point they stop accelerating. Your elevator will take days. There have been a few experiments with astronauts in a centrifuge at 1.5G for approximately a week. (<https://space.stackexchange.com/questions/6154/maximum-survivable-long-term-g-forces>) They didn't have any ill effects but they're also the some of the fittest people on the planet. I'm also assuming the people riding this elevator have grown up on Earth. Nobody really knows exactly what limits a person who grew up in reduced gravity can have. If these people grew up on Mars, the most specific answer anyone will be able to give is "Less than someone who grew up on Earth". The surface gravity of Mars is 0.376G, which means you get 0.624G for free. A person riding the elevator up would just feel the same force as that of gravity on Earth. They will notice the acceleration, but it won't strain them at all. Assuming the tests I mentioned above are valid for everyone, not just astronauts in peak fitness, this means your elevator can accelerate safely at 2.124G at least, and to the rider this will only feel like 1.5G. You may also get a lot higher if you change the rider's posture. The seats in fighter jets are pretty reclined, they're almost laying supine in them. This is so they feel the G's pressing down towards their back, not towards their feet, reducing how hard it is on their cardiovascular system. Fighter pilots only pull these G's for a few seconds at a time, so I can't say any specifics as to how much, if at all, this will help your riders, but it's something to consider. The return trip can be even quicker, since Mars' gravity is working with you. You should be able to safely get 2.5G assuming the previous figures. When calculating how long the trip will take, remember to keep [Jerk](https://en.wikipedia.org/wiki/Jerk_(physics) "jerk") low. Also remember your cars will probably have speed limits near the stations. These combine to mean that any trip will likely be a little longer than your calculations suggest. In conclusion, I can't say it will be a fun ride, but the passengers won't die or be maimed. [Answer] TL;DR: 47 minutes and 20 seconds at constant one-gee felt by the passengers. An important thing to consider in this sort of problem is that there are, in the rotating reference frame, five separate forces we need to consider: gravity, centrifugal force, Coriolis force, drive, and the constraining force of the cable. Given as constant the mass of Mars and its sidereal period, and assuming a spherical Mars, this gives us the forces varying as follows: Gravity varies inversely with the square of the distance from the center of Mars ("radius") and acts downward. Centrifugal force varies directly with the radius and acts upward. Coriolis force varies directly with the speed of the car and acts laterally. Drive is controllable and acts upward or downward as needed. Constraining force is exactly counter the Coriolis force and is the reaction of the cable against the Coriolis force produced by the car's velocity. Now let us assume that the passengers will prefer to feel one-gee pressing them to the floor the entire trip. This does not mean that they are accelerating at that rate. Just consider vertical forces momentarily. Gravity acts against that one-gee, weakening with altitude, and centrifugal force acts with the drive force to pull the car upward. Once the car begins to decelerate, gravity helps despite its weakening strength, and centrifugal force pulls against the floor of the car. Now by definition, areostationary orbit (the point we are trying to reach) is at the altitude where gravity and centrifugal force exactly counter each other, so we will see the total surface-ward force on the car before applying the drive vary from Martian surface gravity down to zero at our resting point. Taking into account only those vertical forces brings us very close to the 47-minute figure already mentioned. However, by numerically integrating (one second intervals on a trapezoidal integration) and examining at various points I found that the velocity of the car produces a Coriolis force at maximum speed of around 12 km/s comparable to Martian surface gravity. That's a significant force pulling the car away from the cable, and the constraining force is felt by the passengers, with the vector sum of that with the drive force at higher than one-gee, angled away from the floor slightly. So instead of a constant one-gee drive, why not have a car that can angle itself (it would have to anyways to flip and decelerate), and have the car's drive vary as needed so that the total force on the passengers is one-gee? By integrating all these forces over time, and using the simplification that rotating the car takes only one second, we find that at 26:00 the car reaches maximum speed of approximately 12.5 km/s, with a lateral force component of 1.78 m/s^2 (0.18 g), flips and begins decelerating, then comes to a stop at the areostationary orbital point of the elevator at 47:20. As to the issue of a tram being able to travel that fast, and it being considered safe - this is in essence a space ship constrained to travel in two directions, and 12.5 km/s is comparable to other velocities of space travel. [Answer] > > What is the maximum G-forces someone can stand COMFORTABLY? > > > I posit that in order for someone to experience comfort that they must remain conscious, so the method by which people are transported having been rendered unconscious is out. ## [I would suggest a G-Suit.](https://en.wikipedia.org/wiki/G-suit) (More accuratley an Anti-G-Suit) It is designed to prevent a black-out and g-LOC (g-induced loss of consciousness) caused by the blood pooling in the lower part of the body when under acceleration, thus depriving the brain of blood. > > A g-suit does not so much increase the g-threshold, but makes it > possible to sustain high g longer without excessive physical fatigue. > The resting g-tolerance of a typical person is anywhere from 3-5 g > depending on the person. A g-suit will typically add 1 g of tolerance > to that limit... > > > So that's 4g acceleration for the average (non-infirm) adult, but... ## Comfort. > > High g is *not comfortable, even with a g-suit. > > > So, give everybody [happy pills](https://en.wikipedia.org/wiki/Morphine). This, from the marketing perspective would have the benefit of generating lots of repeat customers by it's [effects](https://drugabuse.com/library/the-effects-of-morphine-use/): > > (it gives) the user feelings of euphoria, intense relaxation, and > decreased perception of pain. > > > Well that (from a marketing department's perspective) sounds comfortable*. ## Maximum velocity and time. Just plug 4g into the equations. I'd say somewhere in the order of 17 minutes either way, and roughly 36Km/s at turnaround. ## Issues. We can assume that the problems of maglev at that sort of speed, such as [magnetic hysteresis](https://en.wikipedia.org/wiki/Magnetic_hysteresis) (the time taken to magnetise and de-magnetise a material) - a suitable technique or material to compensate would have been found. Compensating for the force of wind at low altitudes and the tendency of atmospheric buffeting to de-stabilise the vehicle will all have been resolved by then. Possibly by enclosing the base of the tether and the first [7 Km](https://www.grc.nasa.gov/www/k-12/airplane/atmosmrm.html) or so: > > The upper stratosphere model is used for altitudes above 7,000 meters. > In the upper atmosphere the temperature decreases linearly and the > pressure decreases exponentially. > > > On your suggestion, the whole thing could be enclosed by the tether as an elevator - that would help. Quick turnaround, happy customers and another plus - you get to market g-suits with your branding on. ]
[Question] [ According to Elon Musk's plans/overall mission, humans could better survive as species if we inhabited more than one planet. So far so good, he proposes settling a million people in a first city after some preparation missions. Now, my question is, how realistic would be to call out for a million people to move there, ignoring questions of transport cost and survivability; this is just a question of how to motivate people. Would they just start selling tickets (maybe an auction with a minimal starting price) (similar to the pre-plot information provided in Passengers and presented in more detail in Lost in space) or what could be other feasible scenarios? I think about colonizing North America where you had to pay the travel and take all the risks yourself, so very minimal living condition was prepared, so people had to think how to protect and support themselves. [Answer] The question remains rather unclear about the setting, so let's look at existing [drivers](https://www.imi.ox.ac.uk/publications/drivers-of-migration) and retarders of migration and see which might apply. Given that we're not forcing people to travel to Mars, we just need to make sure that the idea (note, not the reality) of living on Mars is more attractive than the idea of staying put on Earth. --- The factors which make people want to move generally break down into two categories: ## Push factors (things that make you want to leave home) The two most common push factors we see today are economic (a lack of work) and danger - these both come in many forms, and are particularly strong drivers because they often make living in the source country impossible. Other push factors are things like lack of freedoms (for example, [wanting the freedom to practice their religion](https://en.wikipedia.org/wiki/Pilgrims_(Plymouth_Colony)) or things which don't pose a direct threat to life, but make life in the source country intolerable). ## Pull factors (things that make you want to arrive somewhere else) These are often economic too, but unlike the known realities of life in the source country, are often based at least partly on promises and hopes. People will move to a city because they believe life will be better there, regardless of whether or not that is true (a famous example of this being [English migration to London](https://en.wikipedia.org/wiki/London_streets_are_paved_with_gold)). Other pull factors can be climatic (think people retiring to the Carribean), idealogical (most famously Cold War defectors), lifestyle based, or any other reason people would want to live somewhere else. --- These drivers are then set against the factors that make people want to stay: ## Factors that make you want to stay where you are Familiarity and family/friends are the big ones here. It's a big deal leaving everyone you've ever known behind, and that's doubly true when moving to a different planet entirely. In general, anything which makes you happy with your life in the source country will make you less likely to want to move. ## Factors that make you not want to go to the destination country For frontier countries, this normally means danger, but other things like hardship (or indeed any of the previously mentioned factors) also apply. ## Difficulties and costs of migration If it's difficult, costly or dangerous to actually make the journey, fewer people will make it. This has been true right the way through history, and is still true in the present day (think of the migrants and refugees attempting to cross the Mediterranean - many of them want to make it Europe, but lack the ability to get there). --- # Applicable factors for Mars As with all other migration, the biggest drivers will be opportunity (on Mars) and danger (at home). If you can ensure that enough Mars colonists do well for themselves then people will want to go there, and it can be pretty safely assumed that there will still be refugees on Earth who would jump at the chance to go literally anywhere else. This isn't as simple as it sounds though - in order to get any real numbers of people you'll need to ensure that people can live on Mars, which really means that you'll need to have built (or organised) your colony before people will move in - wealth means nothing if you can't spend it, and opportunities mean nothing if you're not alive to make use of them. One unusual driver is the excitement and adventure of living on Mars - [Mars One received more than 200,000 applicants](https://www.theguardian.com/science/2015/feb/17/mars-one-shortlist-the-top-10-hopefuls), even with no possibility of return. Of course, being on a different planet is a formidable challenge for a colony. Given that regular people don't have the resources to get to Mars on their own, a prerequisite for migration will be an already existing space transport service to get them there. Basic economics tells us that demand and price are inversely correlated, so for maximum numbers of migrants it should be as cheap as possible - financing options such as [working one's passage](https://en.oxforddictionaries.com/definition/work_one's_passage) will also help. Space travel is also risky, so you'd want to make your service as safe as possible too - again easier said than done. ## Conclusion The reality is that, as long as you make Mars colonisation possible, motivating people to move there won't be a problem. [Answer] If you build it, they will come As long as the frontier is a) accessible and b) has some kind of opportunity, people will find a way. Indeed, the question isn't likely how to attract a million immigrants, assuming you can physically transport, clothe, feed, and otherwise provide for them all: it will be stopping at a million. So think about why people immigrate in real life: jobs, primarily. What kinds of jobs would be available on Mars? Well, it has potential for a lot of different types of scientific research. Once the scientists are there, they need support: they need food to eat, materials to build their homes and workplaces, electricity to power them. They'll need entertainers and street cleaners and architects and lawyers and, in general, all the trappings of civilization. (And all of those people will need food, homes, etc.) Sure, some of these services can be provided telepresently from Earth, but there will always be someone who thinks they can undercut the competition by going local. The market will provide. If you're interested in hard numbers, you might look at cities in the million-people region and look at their census and demographic data. Try to suss out how many are in primary businesses like industry and research, and how many are supporting them, whether in the service sector, in government, agriculture, etc. You only need to provide impetus for the first part; the second part will come naturally to see to the colony's growing needs. [Answer] My answer? Taxation. Think about it- offshore banking, and use of tax havens, is big business. But governments across the world have been cracking down on offshore bank accounts and tax havens, since the turn of the century; increasingly so, in the last few years, and the next few years to come. Now, given the costs of moving to Mars, and the costs of living on the Martian colony in the initial phase, in order for Elon Musk and Space-X to turn a profit, they'll need to make a lot of money per passenger; only rich people are going to be able to afford it anyway. So why not market it, and turn a profit on the colony, by establishing it as the very first offworld tax haven, and offworld financial center? Market it to all of the world's biggest companies- Apple, Amazon, Alphabet, Microsoft, Facebook, Alibaba, Berkshire Hathaway, Tencent Holdings, JPMorgan Chase, Exxon Mobil and all the rest- as the next step in tax avoidance and tax sheltering. Get them all to shift their main corporate headquarters there, offering them corporate tax rates lower than those of any jurisdictions on Earth, and they'll do it in a heartbeat; in doing so, you'd easily have a chance of making your Martian colony profitable. With all of the world's largest corporate headquarters shifted to Mars, so do all of the world's most lucrative job opportunities in the corporate sector. Along with those of the banking sector; minimal to non-existent taxation on personal income, wealth and inheritance would be more than enough to induce the world's mega-rich to relocate there as well. Essentially, the Martian colony (/colonies) would be employing a similar economic model as Bermuda, with import duties, payroll taxes and consumption taxes in lieu of income taxes, inheritance taxes and corporate taxes. The world's governments wouldn't be too happy about it, sure; but what're they gonna do? Space-X now has offshore floating launch platforms, from which its reuseable rockets can both launch and make controlled landings. And this isn't a government project; this is an entirely private effort. With Musk having been the very first to shift his own corporate headquarters to his Mars colony, they couldn't hold him to account for tax avoidance any more than any of the other companies. What are they going to do? Build up a militarized space force, demand the taxes that the worlds' nations are due, and start an interplanetary war over it...? [Answer] If we can make it accessible and there are opportunities for people it won't be a problem. If enough infrastructure is in place to deliver building materials for all sorts of development people will take the risk. If construction materials are can be produced locally then prices will be more reasonable and you can bet that someone would quickly build a resort. Check out Isaac Arthur outward bound series on youtube for more inspiration on these subjects, highly recommended. Especially one of the later namely the [Ceres episode](https://www.youtube.com/watch?v=LqoYtBZAKO0) gives a plausible scenario where we are not speaking of just extremely well educated people moving to take the opportunity. [Answer] I'm pretty sure you could get at least a million, probably a lot more, volunteers willing to sell everything and move to Mars, I would if I was unattached. I'm only thinking of professionals you'd actually need for the job, there'd be far more who you wouldn't need or want. The only motive many many people will need to take this on, even knowing the real risks, is a sense of adventure. The trick isn't getting a million people to go, its thinning the herd so you can justify to the rest only sending a million people. [Answer] How realistic would be to call out for a million people to move to... Antartica? You can test out all the answers here by applying them to Antartica. Ignoring transport and survivability, neither are a very nice place to live. Mars is less hospitable than Antarctica, and Antarctica has marketly low migration. Only temporarily manned research bases - arguably, comparable to the space station. The thrill of adventure motivates the extremely adventurous, but there might not be a million qualified candidates. So... we arrive at your question. The obvious one would be money/jobs obtained from some resource, such as mining or agriculture. But transport costs of almost all minerals make it not worthwhile (if we account for their transport, not of the colonists). Perhaps some extremely high value/low mass resource? Or, for non-earth use, such as satellites, spaceships, spacestations etc. Agriculture and spices etc seem to be out. Tourism could be an industry, but there aren't enough super-rich people to support an industry. However... there may be something valuable there that we don't know about, and we just wouldn't have thought of before we saw it. That's the true nature of exploration. [Answer] Assuming that you've solved the cost and habitation issues (for instance, it's being fully funded by an insane wealthy person), then look at it this way: Currently, there are some 7 billion people on Earth. That's 7,000 million. You want to move 1 million people to Mars, or less than 0.1% (less than 1 in 1000). If you're just looking to fill a quota without much care for who goes, it should be fairly straightforward to get to 1 million volunteers. Humans are an adventurous species, and you need less than 1 in 1000 people to be interested. The tricky part won't be finding enough volunteers - you might have trouble finding enough good volunteers, but just filling headcount seems quite workable. [Answer] Under current circumstances, a large-scale Mars colonisation driven entirely by economic interests is not going to happen. * Life on Mars is far more dangerous than on Earth. Deadly atmosphere, radiation, no way to obtain food or water without using lots of technology, etc. * There will be a very low quality of life on Mars. You are going to live your life locked into a pressurized shelter. * Space travel is prohibitively expensive. + Those few billionaires who could afford a ticket to Mars have important jobs and enjoy a high quality lifestyle on Earth. They wouldn't want to relocate to Mars, nor would anyone want them to. + Minorities who want to flee from Earth to escape persecution won't have the money to afford it. A refugee camp is not a good place to build a rocket. + Turning Mars into a penal colony would not make much sense because just locking people up in max security prisons for life is still cheaper * There are no known resources on Mars which couldn't be obtained much cheaper on Earth or through asteroid mining. How could you as a world builder fix these issues? * Invent new technology which drastically improves the survivability and quality of life for Mars colonists and which isn't prohibitively expensive. * Invent a new space travel technology which reduces the cost for transporting people and resources between Earth and Mars by several orders of magnitude. * Make up some resource with very useful economic applications which only exists on Mars in order to make a "gold rush" scenario plausible. * Make the situation on Earth so much worse that Mars seems better by comparison. Resource exhaustion, ecosystem collapse, natural (or man-made) disasters, etc. * Create [a quirky legal loophole which creates a financial incentive for colonizing Mars](https://worldbuilding.stackexchange.com/questions/52573/economic-reasons-to-put-people-on-mars/56998#56998) [Answer] I can't imagine anyone would be FORCED to go to Mars by any government. While it is true that not having all our eggs in one basket is better for human survival as a whole, no government is currently support that idea and backing Elon. This is a private effort, and Elon has no power to force people to go into space like a government might. With that in mind, Elon's attempt to get humans onto Mars would be a fully privatized effort and therefore a volunteer basis. If Elon can get his wanted 1 million or falls short by tens, hundreds, or thousands of people is entirely out of his hand. Maybe no one wants to go to Mars and then no one goes. If a government got behind Elon, perhaps it could be a military style conscription, but there's likely going to be strict physical requirements for the first humans to colonize Mars to ensure they're healthy and up for the task. This also isn't even taking into account mental state for someone who will be mostly cut off from contact with the rest of the world. [Answer] You don't need to motivate people to go to Mars: A lot of people will volunteer to go as soon as you need it. Just look at the [Mars One project](https://en.wikipedia.org/wiki/Mars_One): * It offered a one-way journey to Mars. * The viability of the project is not clear, a lot of people think it is delusional or just a scam. And more than 200.000 people volunteered! Just offer a real opportunity to go to Mars and you will have millions of people eager to go. [Answer] Surely with lower gravity, the best reason to go to Mars would be to create infrastructure for further onward travel? If you could mine enough metal it would be a lot cheaper to get that into space. Build your orbital construction platforms for missions to explore and mine the asteroid belt and outer planets. You don't want the general public going - not at first at least. You want skilled designers, engineers and construction & maintenance workers. Once that population gets big enough, and there is a viable working colony, those workers may want to bring their families over, kickstarting a colony. Your biggest problem though is going to be food and water. Importing from earth is going to be financially crippling and growing your own is going to have all sorts of risks. Failed crops will not be an option. ]
[Question] [ I have this race of space-dwarves and I need to make them homeless due to technological hubris of some kind: for plot reasons. I think that if they were to attempt to build some kind of Dyson sphere and then it collapsed into the sun it could add enough mass to the sun to make it go nova or fizzle out or at least dramatically shorten the lifespan. Especially if the main elemental component of the Sphere was Iron, which can't be fused for energy. > > * Is this plausible? > * How massive would the sphere-in-progress have to be to create a problem? > * What would happen to the star? > > > Please bear in mind when answering * The dwarves in this setting are VERY co-operative * They follow the maxim: "If Brute Force isn't working, you're not using enough of it!". * Resources aren't a problem. -They have some sort of super-steel that is strong enough to be used in the construction of a Dyson Sphere, but if it would cause a more interesting result, then non-iron-based substances will be considered. [Answer] I really don't have the astrophysics background for a detailed calculation, but I do understand that in order to destabilize a star by throwing mass at it you must use a lot of mass. In order to get some ballpark figures, suppose the star is Sun-like and the Dwarves have managed to build a Dyson sphere of solid iron at a distance of 1 AU. The volume of iron contained in said Dyson sphere can be calculated easily: $${{4 \pi} \over {3}}(R^3-r^3)$$ where $R$ and $r$ are the outer and inner radius, respectively. For a Dyson sphere with a thickness of 1 m, that gives $2.8\times10^{23} m^3$, which is four orders of magnitude smaller than the volume of the Sun. Any main-sequence star will be a lot less dense than iron, and anyway you could use some denser material, thus bringing the thing down to three orders of magnitude. Or you could make the wall thicker. A Dyson sphere with a 100 m wall of osmium at 1 AU would have a mass of $6.3 \times 10^{29} kg$, about one-third of the Sun's. That should be fairly destabilizing, I think, but as I said, I have no idea what it would actually do. [Answer] ADDENDUM: In response to @Frostfyres comment below, here is the idea summarized: Add large quantity of fissile element to star in hopes of prolonging its life. The result is other than is intended. ADDENDUM 2: From the comment, @Douglas looked the linked question from the astronomy stack and took away that the answer was "No". The answer there is actually "Maybe". Below is the relevant text copied from that answer. . > > If you have a material inside that slows the reaction, absorbs and > re-admits Neutrons you could probobly generate a sustained burn - > similar to what happens inside a nuclear plant while maintaining > enough gravity to keep the object in one piece and over time, That > would heat up and glow like a star in time and last for a while. > > > In my answer the dwarf describes that this, in their pride, is what the dwarves tried to do. As regards "completely unrelated" I would plead it is not complete: the answer includes a dwarf, and a star. ADDENDUM 3 From @MozerShmozer's comment. The link is about a large mass of fissile material. Q:Could it act like a star? A:Maybe it could. OP: The dwarves have a fusion star. They screw it up. How? My answer: With their skill they build it a fission heart, like the thing described in the link. They put it in their fusion star. It is classic hubris: supreme technological skill versus the inevitability of death. This makes for a good story because as in other cases when science opposes death, the dwarves do not need to screw up or blunder. They can be correct in their estimation of their skill, succeed in their attempt and then be horrified at the result. It is ironic that I thought this was such a cool scifi answer, but failed so hard to convey it to an audience I thought would be right there with it. I will keep the day job. ## --- “We knew that soon Grandfather would die, and burst. When he ran out of the light stuff that drives him.” Tys watched the dwarf roll something between his fingers as he spoke – a well worn piece of some machine, she guessed. It shone like nickel. “You call your sun Grandfather?” He nodded, the nickel piece clicking against his rings. “Because we love him, and we hide from him. And we knew he would die. We thought of a way to help him.” The dwarf flipped up the bit of metal and quickly used it to deeply scratch a perfect circle in the table top, dividing it neatly into pie shaped tenths. He blew the scratched pieces of table away and then set the metal bit down in one section. “Fusion happens only with the light stuff – the starstuff.”. He looked at the circle and back at Tys, apparently thinking that this scratching would serve as some sort of visual aid. Tys nodded. The pie on the table did not mean much, except that they should cover it with a placemat before they left. But she did understand fusion. The dwarf, satisfied, looked back down and rolled the metal bit over two pie slices. “When the light stuff is gone, he dies. Withers, or bursts. But we thought – could he live again, but in a different way?”. As he spoke, the dwarf looked past Tys' ear at something that was not there. “Like the ones who dive deep when they die, living in the dark tunnels on the glow of the earth?” Tys looked at him quizzically. “Dive deep?” He cut her off, his mind far away in a different place and time.. “We had long known the method to make energy from the heavy stuff – the fission. The second greatest energy. Some thought the first.” He moved the metal piece across the circle to rest in a different slice, and laid his thick finger beside it. “And then in space we found the burst heart of a star long dead, made only of the heavy stuff. More than any could use in a thousand thousand lifetimes. And we thought: if with our skill we could rebuild this dead heart and give it to Grandfather it could become his own heart. And in his grip that dead heart could come back to life with fission. He would gain a new youth. New life.” The dwarf fell silent. “So?” asked Tys. “Did you give him the dead heart? Did it work?” The dwarf scooped up the old metal piece, gripping it tightly in his palm. She could see the tendons stand up on the back of his hand. “Yes we did.” He looked at her bleakly. “And yes… it did.” <https://astronomy.stackexchange.com/questions/10294/is-a-star-powered-by-fission-possible> [Answer] One Thing that the space dwarves may have done is in their home system their star was reaching the end of its current stage of life and was either going to expand into a red giant (consuming most of the planets) or go super nova. The dwarves in an attempt to prolong the life of their star they attempted to remove mass from their star in a process known as star lifting. (<https://en.wikipedia.org/wiki/Star_lifting>) However since I think they would probably use the Centrifugal acceleration method since it's the fastest it puts anything in an equatorial orbit of their star at risk of being hit by greatly increased solar winds if the collecting device fails Your dwarves could have been gathering mass from the star at a frightening rate when one of their collectors failed bathing their home system in strong solar winds, bleaching the surface of planets and burning stations out of the skies. The only survivors would be those on the ring around the sun which is generating the solar winds and those in the furthest reaches of the system with their homeworld destroyed. Without the support of the rest of their civilization the starlifing stations quickly succumb to their hostile environment and fall into the star with its occupants fleeing. At this point nature takes its course and the star that was going to go super nova anyway continues to do so, the dwarves having failed to remove the mass necessary to keep it alive. I know this answer doesn't answer your question as intended but it does make your space dwarves homeless by their own hubris. [Answer] I'm not sure on this one but it's at least in the realm of plausibility: The dwarves really like their star system but it doesn't have enough planets. Thus they go out to other stars and find planets they like and bring them home. They have a stardrive powerful enough to boost planets to high relativistic velocities. They do not have FTL communications. One day there's an accident. Just before deceleration was to commence a planet they were bringing home suffers a collision with a substantial body. The impact was about as much as the planet could take without being destroyed in the process. The stardrive was destroyed and the crew killed. The dwarves were being careful in moving their planets, they always ensured that at no point in it's trajectory would a planet be dangerous if they lost control. They carefully kept the path of the planet from intersecting their star--but the impact was off center, the planet was deflected slightly. It plows into their star. Since they have no FTL capability they do not know anything is wrong until they see the flash of light and by the time they see it it's far too late for an intercept mission. [Answer] They could have a technology that was able to manipulate basic constants of physics, leading to the fusion rate of the star increasing by many orders of magnitude. Increasing fusion cross-sections would make starship fusion drives far easier to produce.. accidentally applying such a field to a star would cause problems. [Answer] Self aware bombs with faulty logic. From John Carpenter's early work [Dark Star](https://en.wikipedia.org/wiki/Dark_Star_(film)) we know of at least one way to accidentally blow up a star. The star bomb was at least somewhat self-aware and goal driven. Its purpose was to blow up stars, and by George, it contrived logic needed to accomplish its purpose. [Answer] Only because I recently finished the [Three Body series](https://en.wikipedia.org/wiki/The_Three-Body_Problem) and this would qualify as an answer to the question asked. Also, this answer contains some details from the third book that might qualify as spoilers. One of the highest of high-tech things a civilization in the novels can do is manipulate dimensionality. After finishing the book I thought, "hold on, if it's possible to create a 2 Dimensional space that upon coming in contact with 3 Dimensional space it sucks everything in like an unstoppable black hole (literally causing the collapse of the three dimensional universe down into two dimensions), how did a civilization test this technology?" So there you go: A civilization is mucking about with dimensional physics, inadvertently creates a chunk of 2D matter which then proceeds to consume their star system, collapsing everything down into an intricate 'painting.' Oops. Heck, it doesn't even need to be this. You could pretty much pick any technology that tries to screw with the laws of physics. FTL travel, teleportation, wormholes, time travel... (typing those out it occurred to me that they're almost indistinguishable) ...and something went Terribly Wrong and it destroyed the entire star system. (I'm immensely amused by the idea of mucking about with time travel and inadvertently sending the whole star system a billion-billion years into the past/future) [Answer] The amount of material required for a Dyson Sphere is orders of magnitude more than exists in the solar system. Perhaps the simplest solution is that they were creating a rotating, habitable Dyson Ring and cannibalized the planets in their solar system, including their home world, to build it. Then a failure in the rings drift correction system, an asteroid, or a huge solar flare destroyed the Dyson Ring and left the dwarves without a planet. This leaves them homeless, even if their star still exists. [Answer] The space-dwarves are using super-steel to build their Dyson sphere. Since resources are no limit, they decided gather iron and the other elements needed for their super-steel from systems out to, say, one thousand light years. Their super-steel is mainly iron in the form of steel compressed to the density of white-dwarf matter. One ton in the cubic volume of a match box. If the space-dwarves can turn their home-planet into a spaceship, this should be trivial exercise in alloy production and fabrication. They tend the mass of their Dyson sphere to provide gravitation to enable the space-dwarves to live in comfort on the surface of the sphere. "Resources aren't the problem." the mass of their sphere will be approximately ten percent or more of the mass of their primary star. They will also import atmosphere for their sphere. Now the ideal method for transporting super-steel and atmosphere via long-range teleportation. Unfortunately, the space-dwarves lack the facility and subtlety in navigation and guidance to ensure their teleported goods arrive precisely and accurately. This is to be expected if their maxim is: "If Brute Force isn't working, you're not using enough of it!". The result is ten percent the mass of their primary star in form of super-steel Dyson sphere components are accidentally dumped into their star. The space-dwarves' star will be contaminated with excess iron. Iron is the least fusionable of the elements. Thermonuclear fusion will come to a halt in the poisoned star. A large amount of the star's thermal energy will be lost in melting and vaporizing the white-dwarf dense super-steel. There will be disruptions to the star that could lead to a nova. It is expected there will be massive disequilibria in the star. This could result in flare activity and excessive coronal mass ejections. The space-dwarves will have no choice, but to head for deep space in their home-planet converted into a spacecraft. Astrophysicists from nearby technical civilizations will arrive in droves to study the effects of iron pollution in the star. ]
[Question] [ Is there a way for a moon to usually appear relatively similar to our own moon, but occasionally appear [much larger](https://i.stack.imgur.com/03vES.jpg) from the planet's surface without causing natural disasters due to extreme gravitational forces? To be clear, the moon should only appear this way for a short time before receding back to its previous appearance. The only way this appearance seems possible to me is through a highly elliptical orbit. But that has the pesky problem of destructive tides. [Answer] Since you are only asking for the 'appearance' of the moon getting closer to the planet, I would say that some periodic phenomenon causes an atmospheric distortion that 'magnifies' the moon's appearance, making it much larger in the night sky. It could be tied to some seasonal events caused by some landscape features, Most likely this would be limited so a smaller geographic area since it would take special conditions to get a good atmospheric affect. I observed something similar one summer evening where I could see details on the moons surface I'd never been able to see before. It was like looking at it through a telescope or maybe binoculars. I've only seen that once, but it was very impressive. I had been told it was called the harvest moon, but looking that up brings up something else entirely. [Answer] Let it have an eccentric orbit anyway An object travels much faster at periapsis (closest approach), so it is only going to spend a brief period of time there. You can avoid the tidal stress by making the moon hollow, or very low density, so that even though it appears large, it has virtually no mass. [![hollow Moon](https://i.stack.imgur.com/I8g8o.png)](https://i.stack.imgur.com/I8g8o.png)[![eccentric](https://i.stack.imgur.com/H97Kdm.gif)](https://i.stack.imgur.com/H97Kdm.gif) If you allow for a fake moon, you can also make it out of reflective aluminium foil, which would have a very low mass. A sail moon can also use the [radiation pressure](https://en.wikipedia.org/wiki/Solar_sail) to hoover, and occasionally come closer to the surface. [Answer] A full or near-full moon close to the horizon already [tends to look huge](https://en.wikipedia.org/wiki/Moon_illusion), largely because it's easier to compare it to things nearby. With a different atmospheric composition, one might also imagine a lensing/refraction explanation that just like the appearance of the sun changes when close to the horizon (it appears larger and many of the colors are filtered out, though you still should NOT look directly at it with human eyes), there's something about the long path of moonlight through the atmosphere that causes a refractive effect leading to a slight increase in apparent size (like a pencil in a glass of water). Waiting several hours for the moon to climb up in the sky causes "receding back to its previous appearance." On Earth, a lesser version of this happens "occasionally" on a roughly monthly cycle when not obscured by weather, interacting with an elliptical orbit. [Answer] The size of the "moon" in your image is huge, absolutely massive. I don't see any way to achieve that with a moon. However if you flip the perspective and instead have the "planet" that people are standing on in fact be a moon around a much bigger planet, for example a gas giant, then it's entirely possible and you could have the planet appear as large or as small as you like. To have the size changing you still need to place the moon that people are standing on in an elliptical orbit. Gravitational effects would cause some fairly large tides but you can reduce that by having smaller oceans. Also the simple fact of having the planet be larger would mean the tidal difference is smaller as the difference in gravitational effect is smaller from one side of the moon to the other. I honestly don't know how much difference this will make and don't have time to do the math at the moment but it would be worth investigating. (To explain: The sun is pulling on us far more strongly than the moon is, but solar tides are weaker simply because the difference in pull between the near and far side of the earth is smaller. You could get the same effect from the gas giant). [Answer] This was a popular thing to discuss in the ancient world and medieval. Al-Hazen (who lived during the Fatimid Califate of Cairo around 1100 AD made significant contributions to the principles of optics, astronomy, mathematics, meteorology, visual perception and the scientific method. ) I believe he was one of the earliest discuss the moons apparent size differential as being an optical illusion. He observed that the moon's angular size remained constant. (So, the atmosphere does not somehow create the illusion.) He then proposed that the sky looks like the flat ceiling of an enormous room, and the rising moon appears to move along it in a more or less flat trajectory, so the moon would look closer at the zenith thus it would look a smaller linear size than it did at the horizon. While not exactly true he paved the way and wasn't far off from the real cause. A crater on the moon carries his name because of his work. [Answer] The moon does have a slightly elliptical orbit, which does cause it to appear bigger at some times than at others; it looks noticeably bigger in the sky when it is at the perigree of its orbit compared with when it's at the apogee. The real-world difference in apparent size between the two is around 15% so it's not insignificant. Tides on the Earth are also affected by this; tides are lower when the moon is at apogee and higher when the moon is at perigee. There is also the phenomenon of spring tides (or more correctly perigean spring tides). These tides occur approximately three or four times a year when the moon is at perigee and simultaneously aligned with the earth and the sun. When combined with stormy weather these tides have been known to cause flooding events. They don't make the moon look any bigger than any other perigee moon; it's the alignment that amplifies the tidal effect. Now, if you want the moon to look even bigger at times, you'll need to increase the elliptical length of the orbit. This will magnify all these effects, to the point that that you would every easily end up with severe flooding problems on a fairly regular basis. You can get rid of the problem of spring tides by putting the moon on an orbit that doesn't cause alignments. To do this, you'd need the moon to have an out-of-plane orbit. That would have a whole slew of interesting side-effects on the earth-moon system, depending on exactly how you set up the orbit, but would allow you to have a more elliptical orbit without having catastrophic floods every three months. You'd still get might higher tides at perigee, but the extra-high spring tides would be gone. In addition, giving the orbit some eccentricity would allow you to have a closer perigee at one end of the orbit, and thus a more infrequent but more dramatic effect when the moon is closest. Again, however, this would have a marked effect on tides in addition to the perceived size. All of the above, however, is at odds with current theories of how the moon formed. If you want orbits like those described above, the moon would probably need to have instead been a wandering object captured into orbit. We don't know of any wandering objects anything like the size of the moon, but it's not impossible. What this does allow though is for the moon to be a different density to reality. If you have a moon that is much less dense, then it can have a lot larger diameter without making any difference to the tidal effect. With an eccentric or elliptical orbit, this would allow you to have a much wider range of visual size. The down side is that at apogee, you'd probably need to set it up with hardly any tides at all. (tides are considered fairly key to some life processes, so this in itself could be as problematic as flooding from too much tide). In any case, I still don't think you'd be able to get the moon looking anything like as big as shown in the picture in the question. For an earth-moon system to have a view like that, you'd be virtually ready for a collision, and yes, the tides would be completely insane. [Answer] Looking at the picture you posted, I don't think you've got any realistic chance of a view like that with an earth-moon-like system. As you say, the tides are too much of an issue. I've posted a separate answer giving you my best shot, but I don't think it's going to work as well as you want. So let's take a completely different tack. How do we achieve an image like the one you posted? Let's paint a scenario where your protagonists think they are on a planet like earth, but are actually in a massive dome structure. If you've seen "The Truman Show", you'll get what I'm trying to visualise here. The illusion is big enough and real enough that everyone is convinced and carries on their normal lives. In this scenario, the "moon" they see doesn't really exist; it's actually just an image projected onto the ceiling of the dome to appear like the moon. (a real moon may or may not exist outside of the dome, but that's not relevant here) The "super-moon" effect occurs when the projector develops a fault. One day the moon appears on the the horizon and is massively bigger than usual. No natural disasters or flooding, as it's just a projection, but obviously the people are freaked out. Cue the guy in your picture... ]
[Question] [ I am more curious about the immediate effects on local and global socio-economics rather than the likelihood of the rest of the world declaring war on China or were the other countries would get their goods from. One day, China stops all exports just out of the blue. The reason why they stopped exporting is not important. I am just interested in the consequences of this event on the rest of the world economy. What would happen the few days immediately following this event? Would businesses stop running? Would it lead to fatalities because people can't get something they need that's normally made in China? [Answer] With many World Building questions phrased as "what if \_\_\_\_\_\_\_\_," it turns out that the thing that happens is not nearly as important as how it happens. For example, take the case where we take your question literally. Absolutely nothing out of the ordinary happens outside of China, but they just stop exporting. They carry on as if the exports were completed (potentially loading empty shipping carriers onto ships. It takes between two weeks and a month for a cargo ship to cross the Pacific, so America doesn't even notice until then. Panic ensues as massive massive quantities of orders are now at least a month behind. Alternatively, if China announces they're no longer exporting, there would be a whole bunch of very rapid talks at a very high level. China's a reasonable chunk of the world economy. Given what we saw in the "Great Recession," our financial systems are stacked too much to even let a small country like Greece let their governmental obligations go. To have China simply stop fulfilling obligations, not just as a government, but as a society, would rock everything. Also worth noting is that, if China stopped exporting, they'd have a labor problem on their hands. They have billions of people living in cities dependent on manufacturing for export as a way of life. Needless to say, this is not the kind of harmony the Chinese governing party wants to see. There is a solution: start making products for the government, rather than for other countries. You didn't want to explore the "everyone goes to war against China" venue, but there's not many thing they could have the factories producing besides weapons. China may, instead, go to war with everyone else! Tl/Dr: how this happens matters more than what happens, and given how incredibly unlikely this event is, the range of "hows" are particularly exotic, and particularly hard to predict. In addition, the world financial system is literally more complicated than anyone knows (as in, even the experts don't know), so something may happen there. [Answer] Total chaos in the rest of the world, followed by total chaos in China. Consider just how much is labeled "made in China" these days. Then think about how much contains some parts which are made in China. If those [products](https://en.wikipedia.org/wiki/Foxconn#China) and parts are no longer available, what then? As Cort pointed out, the Chinese are getting paid for their exports. If their markets suddenly go away, they have a problem. Even if they fulfill all existing contracts and simply refuse to sign any new ones, their internal markets would crash. [Answer] Prices would skyrocket. Manufacturing would ramp up like nuts. In the USA, there would be more anxiety than real harm. Cost of living would spike for a bit, which would cause most problems. We are dependent on foreign oil, though, and rare earths, so electronics would rocket up in price the most, but only because we have such limited supply--mostly from China. We have everything we need in raw materials, though, just not in fully realized industrial supply. After some sort-term anxiety, though, we'd resupply or restart native production in anything especially painful. Rare earths are a biggie. Some people are trying to reestablish refineries here to limit this problem, as it happens. [Answer] The world would simply buy its goods from somewhere else (probably a lot of somewhere else's). After a blip of disruption the world would quickly adapt. China on the other hand would be deeply and permanently affected. Their economy would collapse, people would riot, their government would be in danger of falling. China would also become very dangerous as any government that stayed in or took power would likely be looking to foreign adventures to bolster the economy and distract the Chinese people. In this regard the world would not do as well. [Answer] The US has essentially [threatened military action against Iran if they block oil shipments through the Strait of Hormuz](http://mobile.nytimes.com/2012/01/13/world/middleeast/us-warns-top-iran-leader-not-to-shut-strait-of-hormuz.html?referer=&_r=0), and [has no problem ignoring warnings to keep bombers away from artificial Chinese islands](http://www.bbc.com/news/world-asia-34805899), so it's no stretch to say that weapons would be drawn in order to keep exports from stopping completely. Hopefully there would be some sort of transition period during which China agrees to (rapidly) ramp down exports rather than cutting them off cold turkey, which should help avert open warfare. Economic sanctions wouldn't work; they're already refusing to sell stuff to you. But it would be hard to define what "China" is for the purposes of this question. Are we only considering products made by wholly Chinese-owned companies? Then the global impact would not be much. But many western companies (not just Apple) have operations in China. If the Chinese government blocks or seizes those other companies' assets, then things would get complicated. In any case, what the OP is asking about would almost unquestionably be seen as an act of aggression. Edit: It would be interesting to see how China then intends to get back [the $1.3 trillion owed to it by the US](http://www.theblaze.com/stories/2013/10/12/chart-who-does-the-u-s-govt-owe-17-trillion-to/), as well as other countries' debt. Do they simply write it off? Are they self-sufficient so they can survive without imports (how will they pay for them? Money generated by purely domestic ventures?)? This would be a sticky situation for the Chinese as well. [Answer] Many answers point to the idea of substitution, and the amount of time it may potentially take for substitution to take place. Assuming the disruption of trade isn't a hostile act by China (lets imagine that China is under total quarantine because the Andromeda strain has broken out there), then there will be many knock on effects. Low wage nations like India, Viet Nam, Indonesia and so on which have functioning industrial bases will see their wages rise dramatically since they will suddenly be on high demand. Billions of dollars of capital investment will also flow into these nations to start creating the factories which will be needed to replace the ones no longer available. This will create massive social and political turmoil as the older social and cultural orders are overturned by the new wealth. The United States has been taking steps to increase the production of Rare Earth elements both in the continental US (reopening old mines, for example), and experimenting with mining the deep sea muds off the coast of Hawaii to recover these elements. These substitution efforts will increase. Africa may descend into chaos since the Americans and Europeans will not be inclined to let their industries be held hostage by raw material shortages, and substitution using clever design and local mining will do for African resources what American Fracking has done for global oil prices. Kicking resource prices down will demolish many third world economies if they don't have the work force and infrastructure for industrial production. Older electronics will become repurposed and forced to stay in service for far longer than they were designed for. An entire service industry of refurbishing old machines will grow rapidly. As well, the software industry will focus on changing code in order to run more efficiently on older machines. "Bloatwear" will be out, and very elegant, stripped down code will be in. This will have interesting effects in the future as new production finally comes on stream, since the hardware will reflect the new ideas of coding. This will also cement the Western military advantage, since the American military and US civil society has the most and most advanced computers and IT infrastructure in both qualitative and quantitative terms. If you can keep using more and better computers than anyone else, then you will be farther ahead when new computer production comes on line. As part of the substitution effort, the US may also jump start many experimental technologies like photonics computers, using DNA as a computing substrate or quantum computers which have no counterparts being manufactured in China (or anywhere else). The wait for new computers will then change into a wait for new low end computing devices like small microprocessors for cars or stoves, rather than higher end devices. Since in the United States there is a "maker" culture of large size and sophistication, there will be a resurgence of thousands if not millions of new "brands" as small shops kickstart to making in demand items, while larger conglomerates which depend on imports will be left hanging or collapse. This might resemble the 1920's, when you could choose from almost 100 different automobile companies for your driving needs. So for areas where there already is industrial infrastructure, the import substitution effort will take place quickly creating islands of relative prosperity. Developing nations which are on the way will rapidly develop to replace the mass production capabilities of China, but this may take a long time. Resource based economies might take a huge hit since there is no longer Chinese money propping them up, and Western nations will most likely be taking steps to use their own resources. Local effects like wars, revolutions, political movements and so on will she to be looked at on a very detailed case by case basis. [Answer] A lot of manufacturing would grind to a halt. The important thing to know... From wiki: > > China's rare earth industry makes up 97 percent of rare mineral trade worldwide. > > > The number might be wrong these days but the principle is still applicable. If China shuts down exports then any manufacturing depending on Rare Earths will stop. That's not something you can quickly spin up a replacement for. What will that kill? There's a partial list at <https://en.wikipedia.org/wiki/Rare_earth_element#List> but the short answer is "lot's of important modern tech". Like Neodym magnets, lasers, fibre repeaters... There'll be other similar problems due to other industries that China has near monopolies on, but the Rare Earth industry is a good example people can relate to. [Answer] First it should be indicated if China stops producing the goods all together, or simply stops exporting them, while still keeping production ongoing. The reason I emphasize this point is to tackle the worldwide prices of raw material. In recent years a drop in the rate of construction of new properties in China has led to worldwide drop in the price of structural steel due to the decrease in its demand. Accordingly, ceasing the production of all China-made goods would lead to an overwhelming drop in all sorts of raw material. This will cause a commodities market crash which will in turn crash all financial markets and thus cause a worldwide financial crisis that will be almost impossible to recover from. The consequences of such a crisis is discussed plenty in the other answers. I just wanted to focus on the input perspective of the idea. ]
[Question] [ By some means, artificial or naturally occuring, a human inhabited star system has been flung from the Milky Way. Prior to being ejected from the galaxy, the system bears at least one Earth-like habitable planet. Following the ejection, would this system still be stable? Would the force required to eject the system cause the orbits to collapse? Would radiation between galaxies make life on this planet impossible? And the most important question, would the planet be able to support a civilization until reaching a nearby galaxy? [Note, this question is not about a rogue planet - ie, a planet without any star - but a rogue star system with a habitable planet around it.] [Answer] It could certainly be stable; it's possible for a star to be ejected from a galaxy and still have other objects be gravitationally bound to it. Observations of the hypervelocity star [HE 0437-5439](https://en.wikipedia.org/wiki/HE_0437-5439) indicate that it was likely originally a triple system. During an interaction with Sagittarius A\, two of the stars were flung away at a high speed bound to each other as a binary system. While they eventually merged after tens of millions of years, this was due to normal stellar evolution -- one swelled up into a red giant and engulfed the other. A similar situation could apply here. Imagine you have [an s-type binary system](https://astronomy.stackexchange.com/q/38745/2153), where the planet is tightly bound to one star (so there are two stars and a planet, as opposed to three stars). During an encounter with Sgr A\, the planet and the star it's bound to are propelled to high speeds, eventually leaving the galaxy. Since hypervelocity stars can reach speeds of ~1000 km/s and the Galactic disk is ~100 kpc wide, it could leave the disk within ~100 million years -- less if the system is ejected at an angle out of the Galactic plane. Of course, an encounter of this sort could very, very easily lead to disruption of the planet's orbit during the close pass to the black hole -- four-body interactions are, uh, not pretty -- but there's a chance that things could turn out the way you want. The bottom line is that invoking this scenario as a background to explain your rogue system is reasonable; the outcome you want is definitely a plausible one. [Answer] ## Should be fine Your safest bet for causing a rogue star would be a galactic collision event in which all the stars that pass through the equilibrium point of the 2 galaxies will shoot off in a more or less straight line. Most will eventually drift far enough one way or the other to fall back into one galaxy or the other, but a few lucky candidates will hit such an equilibrium that they could pretty much keep going for tens of millions of light years. If this is your mechanism for ejection, then the star will not necessarily encounter any spectacularly energetic event to be ejected. It will just go straight instead of slowly curving... so as long as it does not run into the shockwave of any colliding stars on the way out, it should be fine. As for intergalactic radiation, this is also not an issue. There is plenty of that between stars inside of a galaxy to begin with. Solar wind creates a natural barrier around solar systems that keeps any sort of interstellar medium out. [Answer] If your star travels at ~1000 km/s, you should reach Andromeda in about 600 million years. Give or take. The sun has an expected lifespan of around 10 billion years, with about 5 billion years left. So it's definitely doable. [Answer] Radiation would not be an issue with the star's magnetic field and the planet's magnetic field and atmosphere. BUT it would be extremely difficult for the planet to remain in a stable orbit around its star whilst the star was being accelerated by a close encounter with another (probably much bigger) star. ]
[Question] [ There's a mystical component to my world that I have been unable to resolve: Why might a divine being not reveal himself when it would otherwise be in his/his followers' best interests. My world has a [Henotheistic](https://en.wikipedia.org/wiki/Henotheism) setting, where a new upstart religion is challenging the incumbent primary divine being. A challenge is put before the two, and the victor deity will likely stand to gain a large number of followers whereas the defeated deity will perhaps have its followers punished or slain. Though my world is in no way related to the Bible , I will include the account of Elijah's challenge to the prophets of Baal as a reference given it is a widely known text and is a close analog to my dilemma, which is a failed theophany: > > And it came to pass at noon, that Elijah mocked them, and said, Cry > aloud: for he is a god; either he is talking, or he is pursuing, or he > is in a journey, or peradventure he sleepeth, and must be awaked. > > > Whereas in my world, we will need something like this (something I made with Dalle2): [![enter image description here](https://i.stack.imgur.com/xjV0L.png)](https://i.stack.imgur.com/xjV0L.png) ### Literature review Intrigued by the similarities, I tracked down a copy of the Ugaritic text that recounts stories/myths of Baal, so that I might find clues unto his nature and why he might not reveal himself. I've learned his power and ascendancy was to a large extent due to El (presumably the former primary deity of Ugarit before Baal) and his sister Anat. His palace was also of considerable importance, not unlike the relationship between Solomon and his temple. However in my world, the deity in question is already at the zenith of his power (in contrast to the dips seen in the [Baal Cycle](https://en.wikipedia.org/wiki/Baal_Cycle) where Baal was still cultivating his cult). ## Question Limiting answers to what is known about near eastern mystery cults of antiquity, what material evidence is there in the archaeological record or literature that could explain a failed theophany of a divine being (when it would clearly be in its best interest). Assume if the god loses the challenge, its followers will be slain. Notes: * The exact challenge that faces this fictional deity is more story-oriented, so I'm leaving that out. [Answer] The question only asks about failure to appear, but this is only one particular instance of failure to respond to prayer or rituals; it makes no sense to address only the specific instance instead of the general problem. First of all, about the request for "material evidence". There is no such thing, and there cannot be. Gods are metaphysical entities; if there were any material evidence about what they did or did not do, then they would be demoted to sublunar physical entities, and they would be gods no longer. We can only have material evidence of what people said about what they thought were the motivations of the gods. But in literature, yes, there have been numerous failures to respond to prayer and rituals. In real life, God or the gods almost always fail to respond to prayer, and almost all rituals are not effective in the material world; so that just about all religions have had to grapple with this problem. Why do the gods fail to respond to prayer or to rituals? Generally speaking, there are only a few broad categories of explanations: * The atheistic position: there are no gods. They do not respond to prayer or to rituals because they are only figments of the imagination of people. * The [agnostic](https://en.wikipedia.org/wiki/Agnosticism) position: may there are one or more gods, maybe there aren't, but in any case we cannot know. Of course they fail to respond to prayer or to rituals, because if they did we would know that they exist. * The [deistic](https://en.wikipedia.org/wiki/Deism) position: yes there do exist one or more gods, but they are not interested in the sublunar world and never interfere with it. * The theistic position: there do exist one or more gods, and they are interested in the sublunar world and do interfere with it. When they fail to respond to prayer or to rituals, that's because... + The [gnostic](https://en.wikipedia.org/wiki/Gnosticism) position: the god or gods who created the world are actually malevolent. + The [dualistic](https://en.wikipedia.org/wiki/Dualism_in_cosmology) position: one or more gods are good, one or more gods are evil, and sometimes the evil god or gods successfully interfere with the good god or gods. + The classical pagan polytheistic position: there are multiple gods, and they are not intrinsically good or intrinsically evil. Sometimes their interests and intentions align with those of mortals, sometimes they don't, and quite often various gods have interests and intentions opposite to those of other gods. + The standard Abrahamic (Hebrew, Christian and Islamic) position: there is only one God, and He loves people, but: - Sometimes He is angry with people. - Sometimes He needs to teach people a lesson. - Sometimes He forgets that He is the only One God, and falls back into a dualistic position. - Sometimes a tragic event is preordained, and not even God can work around it. - Sometimes something bad must happen so that the magnificent universal plan of God can progress. - Sometimes the person who prays or performs the ritual is an unworthy sinner and God does not respond to the prayers or rituals of unworthy sinners. - Sometimes the prayer or ritual is performed incorrectly, and even God has limits in what He accepts. The absolute champion of all times at failures to respond to prayer and rituals is of course the One True Living God of Abraham, worshipped by the rightfully called [Abrahamic religions](https://en.wikipedia.org/wiki/Abrahamic_religions). It helps that He is the God of the Bible, the world's greatest and best known (semi)coherent collection of mythological texts. (All quotations are from the King James¹ version of the Bible.) ¹) English is not my native language. The King James version is the only English version of the Bible of which I am sure that at least some native English-speaking people consider standard. * God is angry -- Judges 2:20-23: The Israelites are fighting a war against the original inhabitants of Canaan, and they rely on their God who has promised them the Promised Land. But woe is them, because their God is angry with them: > > And the anger of the LORD was hot against Israel; and he said, Because that this people hath transgressed my covenant which I commanded their fathers, and have not hearkened unto my voice; I also will not henceforth drive out any from before them of the nations which Joshua left when he died: tThat through them I may prove Israel, whether they will keep the way of the LORD to walk therein, as their fathers did keep it, or not. > Therefore the LORD left those nations, without driving them out hastily; neither delivered he them into the hand of Joshua. > > > * God is angry -- Ezekiel 16:26 sqq. The God of Israel is angry with his people, and expresses His anger in the most graphical way. Remember those are the direct words of God: > > Thou hast built thy high place at every head of the way, and hast made thy beauty to be abhorred, and hast opened thy feet to every one that passed by, and multiplied thy whoredoms. Thou hast also committed fornication with the Egyptians thy neighbours, great of flesh; and hast increased thy whoredoms, to provoke me to anger. Behold, therefore I have stretched out my hand over thee, and have diminished thine ordinary food, and delivered thee unto the will of them that hate thee, the daughters of the Philistines, which are ashamed of thy lewd way. > Thou hast played the whore also with the Assyrians, because thou wast unsatiable; yea, thou hast played the harlot with them, and yet couldest not be satisfied. Thou hast moreover multiplied thy fornication in the land of Canaan unto Chaldea; and yet thou wast not satisfied herewith. > > > > > [...] And I will judge thee, as women that break wedlock and shed blood are judged; and I will give thee blood in fury and jealousy. And I will also give thee into their hand, and they shall throw down thine eminent place, and shall break down thy high places: they shall strip thee also of thy clothes, and shall take thy fair jewels, and leave thee naked and bare. > > > * God wants to teach His people a lesson a lesson in submission; Ezekiel 16:22 sqq. > > Nevertheless I will remember my covenant with thee in the days of thy youth, and I will establish unto thee an everlasting covenant. Then thou shalt remember thy ways, and be ashamed, when thou shalt receive thy sisters, thine elder and thy younger: and I will give them unto thee for daughters, but not by thy covenant. And I will establish my covenant with thee; and thou shalt know that I am the LORD: That thou mayest remember, and be confounded, and never open thy mouth any more because of thy shame, when I am pacified toward thee for all that thou hast done, saith the Lord GOD. > > > * God refuses to respond to the prayers and rituals of unworthy sinners, in this specific quotation, King Saul; 1 Samuel 28:4-6: > > And the Philistines gathered themselves together, and came and pitched in Shunem: and Saul gathered all Israel together, and they pitched in Gilboa. And when Saul saw the host of the Philistines, he was afraid, and his heart greatly trembled. > And when Saul enquired of the LORD, the LORD answered him not, neither by dreams, nor by Urim, nor by prophets. > > > * In a moment of levity, God makes a wager with Satan; Job 1:6 sqq. > > Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them. And the LORD said unto Satan, Whence comest thou? Then Satan answered the LORD, and said, From going to and fro in the earth, and from walking up and down in it. > And the LORD said unto Satan, Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil? > Then Satan answered the LORD, and said, Doth Job fear God for nought? > 10 Hast not thou made an hedge about him, and about his house, and about all that he hath on every side? Thou hast blessed the work of his hands, and his substance is increased in the land. But put forth thine hand now, and touch all that he hath, and he will curse thee to thy face. > And the LORD said unto Satan, Behold, all that he hath is in thy power; only upon himself put not forth thine hand. > So Satan went forth from the presence of the LORD. > > > * Tragedy is preordained and unavoidable, as a step in God's plan for the salvation of mankind; Luke 23:28 sqq. > > But Jesus turning unto them said, Daughters of Jerusalem, weep not for me, but weep for yourselves, and for your children. For, behold, the days are coming, in the which they shall say, blessed are the barren, and the wombs that never bare, and the paps which never gave suck. Then shall they begin to say to the mountains, Fall on us; and to the hills, Cover us. > > > * Jesus Christ cannot reveal His divine power because his suffering and death is an essential point in the plan for the salvation of mankind; Matthew 27:41 sqq. > > Likewise also the chief priests mocking him, with the scribes and elders, said, He saved others; Himself he cannot save. If He be the King of Israel, let him now come down from the cross, and we will believe him. He trusted in God; let Him deliver Him now, if He will have Him: for He said, I am the Son of God. > The thieves also, which were crucified with him, cast the same in his teeth. > Now from the sixth hour there was darkness over all the land unto the ninth hour. And about the ninth hour Jesus cried with a loud voice, saying, Eli, Eli, lama sabachthani? that is to say, My God, my God, why hast Thou forsaken Me? > > > [Answer] There are various stories around the life of [Kūkai](https://en.wikipedia.org/wiki/K%C5%ABkai), a Buddhist monk who founded Shingon Buddhism and brought Chinese writing to Japan. One of [these storie](https://henro.co/kukai-early-life/)s goes that, as a 7-year-old child, he climbed to the edge of a cliff and jumped down from it, shouting to Buddha "If I am destined to save the world, save me, else let me die". Some commentaries to the story end with a > > and Buddha gave in to the temptation and saved him. > > > And this can explain the failed theophany: a god that has to give in to a human request/challenge to prove itself can be somewhat seen as a lesser god than one who can be believed based solely on faith. Challenging a higher authority is already lessening it. [Answer] This has come up in plenty of literature I've seen. The usual explanations come down to either it's too expensive to do so, some other force prevents them, or they just can't be bothered to. Here's a quick list of the main options, in no particular order. God's just don't work that way. I doubt this is the option you will want to go with, but it's possible divinity just doesn't work in such a way. Maybe your god doesn't have a physical body, and works mostly by inspiring his disciples to do something. He just doesn't have the ability to show up or do overt miracles because deities are more limited then that. Your god wants faith, confirmation of his existence removes the need for faith Your god could prove himself, but he wants his priest to work out of faith without proof. If your god proves himself to the unbelievers he also proves himself to his believers, and in so doing removes the ability of them to have faith in him without proof. There are a few variants of this option. * Gods are powered by (or otherwise benefit from) faith, the kind of faith that only is possible if one believes in something without absolute proof. * This is a test of his followers, so they can prove they are wiling to support him even in hardship or without faith (which is kind of a jerk move, but hey the majority of gods in religions kind of are jerk). It's a temporary test, he will get around to helping eventually A slightly less jerk version of the last option. He is temporarily refusing to prove himself to test his faithful. He want's to see if they will past his test by continuing to have faith, stand up to hardship, etc. Only after they prove themselves will he show himself. So maybe he doesn't do a miracle on demand and his faithful are captured, but then he does a different miracle to help them all escape once they refuse to refute him even in that situation. For a biblical comparison look at when god asked Abraham to sacrifice his son, then told Abraham he passed and didn't actually need to do it when Abraham showed he was willing to do so. Your god doesn't want his faithful to be dependent on, or make demands of, him If he shows up now and does a miracle for you why wouldn't he the next time you're in trouble? What happens when a priest offers to have his god preform a miracle to earn a room for the night? A believer gets in a drunken bar fight and offers up all his money if his god doesn't prove his existence right now? In short this is the slippery slope argument. If his faithful can demand his appearance because it would be convenient for them they may become dependent on that. He wants them to be able to function without his constant intervention and daily proof of his existence, and so they need to learn to function without on-demand miracles; even if the lack of them is going to be a significant hardship. God helps those who help themselves A very close variant of the last idea here. Your god only intercedes to help people after they have put in will effort and done what they can by themselves, so they don't get lazy and dependent on him. Thus he won't do his miracle yet because he needs his people to first 'help themselves.' In this case that might mean they have to fight in this competition on their own, at least at first, and prove themselves before he will come in and help out at the end. You have angered me and the LORD is vengeful and strong in wrath Maybe your god doesn't help because you have angered him and no longer deserve his aid. Perhaps he didn't want this competition, or he is angered they make demands on him to prove himself. Maybe they have done something entirely unrelated to fail him but their punishment is his lack of help here. The point is his lack of aid is because of their short comings. You might recognize the second half of this section title is actually a biblical quote, and for good reason. There are a multitude of examples in the bible where God's chosen people suffer defeats, hardships, and humiliations. From being enslaved in Egypt to having to wander a desert for 40 years to countless military failures. In practically ever case the reason the bible gives for God not intervening to aid his people is that they had done something to anger him and prevent him from coming to their aid; in fact some of the hardships were actually intentionally inflicted by God as punishment. There are plenty of examples to draw on for why your god might end up unwilling to help his faithful. The nature of divinity prevents an overt show of power Even god's aren't omnipotent and are limited in what they can do. I've actually seen many variants of this idea, but they tend to be similar enough I won't list them all. The most common version though is that there is another even higher being, entity, or simple nature of the world and divinity that sets limits on what gods can do. This limit prevents the god from doing the sort of overt demonstration. For instance maybe miracles have to have a plausible explanation. If a god does something so overtly impossible as to have no other explanation he will incur the wrath of a greater entity or trigger some other terrible consequence. Perhaps anyone that sees an overt miracle without a plausible explanation will somehow be driven made with the revelation. Maybe witnesses to such miracles will simply be immediately killed by the greater power that doesn't want humans to see undeniably proof that deity can work outside the realm of nature. That's not how the god of X works Many gods in fiction are gods of certain ideas or concepts, and those concepts don't only define them but also may constrain them. The god of fire is not going to, and might not able to, do a miracle involving creating a giant ice sculpture, because he isn't the god of ice. Their godhood, and the concept they are tied to, thus set rules and limits on how they manifest their powers which may in turn prevent them from manifesting here. Here we can piggyback a bit off of past ideas for inspiration on what your god's nature and thus limits might be preventing his manifesting here. If your god is the god of faith he may be dependent on his people acting on faith instead of demonstrations for instance. If he is the god of humanity and connections he may work through inspiring his people, suggesting they help each other, moving them in the right place to do the most good etc; but in turn since he works through people he doesn't do great miracles. Alternatively perhaps he is the god of luck/timing/coincidences who inspires his people to keep an eye for the right time to move and his miracles work by slightly nudging odds to make coincidences work in his folks favor. In this case he may be helping his people all the time, but because he is only nudging odds to make things work out better for his people even when he works a miracle it will look like a coincidence, and as such won't be very convincing as a miracle. I could go on and on, but since I suspect this isn't he path you will take so I won't waste my effort. The point is it's easy to make the nature of his particular power and providence one that doesn't lend itself to fancy overt miracles, even as other gods with different powers can do them. It's part of the goods deal/bet The two gods in this dispute have an agreement that they will allow their faithful to solve this situation without their direct involvement; thus neither side can actively get involved. There are many reasons for this. 1. There might be some convention or pact between all gods which sets rules for how they interact in the world, and some of those rules include allowing disputes between two set of faithful to happen without direct intervention. 2. Close variant of the last option: Direct intervention in faithful disputes is the nuclear option. That is to say anyone could do it, and if they did it would be highly effective. Unfortunately as soon as they do they open up the door for everyone else to do the same. A world where gods are constantly actively participating in fights between faithful is considered undesirable by the gods, either because it's too costly for the gods or because it would lead to so much devastation to humans. Thus there is a sort of unwritten agreement no one will intervene in such disputes because they don't want to force the other gods to do the same in the future. 3. The more established and powerful deity has been convinced to not get involved via plea from the new god, deal with other gods, general good sportsmanship, or some other contrivance to not act directly so long as the other god doesn't. The new god considers not proving himself to be an acceptable sacrifice to get the other deity to agree to not get involved since he knows he would lose in a competition in which the two were directly involved. Thus he stays hands off so the other one will as well. 4. It's a trial by champion, using their believers to solve their dispute so they don't have to. God vs God battles are bloody and everyone looses. Thus the gods usually allow their faithful to handle disputes in their place. They have set laws and rules for how such disputes can be handled, which allow certain types of aid to their followers, but forbids others. The rules of such trial/disputes prevent the sort of overt intervention you suggested. 5. It's all part of the bet. Remember when I said many gods are jerks? well that's going to be a reoccurring theme in these answers. Perhaps your gods aren't treating this as a life and death competition, but instead as a fun parlor bet. They want to see what's happening and have made a good natured bet on the results. Now their let those petty human things, which they consider barely more then ants and don't really care if their hurt, play out their dispute to see what happens and which god needs to buy the other an ambrosia beer. The other god is preventing him Nice simple one, the more powerful god is powerful enough to get in the way of the weaker one. The weaker one can't use his power as long as the stronger one is blocking it. He hasn't yet risen to his proper power as a god Your god is weaker and lesser known, there is a reason for that. He had been locked away in some prison in the past, or injured, or is new and still developing into his godly strength. Whatever the cause he is currently handicapped and limited, and his people know that. They hope to help him grow to his full power, and in so doing gain his blessing and future support for their aid. However, in the meantime it's known he is quite limited and may not yet be able to pull of an impressive miracle. He deems it too expensive Gods may not be all powerful. They can do miracles, but doing them isn't easy. It requires some expense of effort, maybe they gain power from faith but then expend it when doing wonderous things for instance. The point is there is a cost to do a miracle and it's non trivial. The god would like to do something here, but he is still weak and has only so much strength. With limited power to work with your god has decided that his resources are better spent in some other way and he just can't afford the expense of doing a miracle here. He doesn't like doing that, but deems it the wisest use of his resources either for himself or for his followers if he is more altruistic. Here I'd point you to an old game Black & White where you play as a god. You often had exactly this tactical decision. Miracles cost faith, you can gain faith by doing a miracle in front of people, but not enough faith to cover the cost of the miracle. You need to pick and choose where to perform your miracles to get the most bang for your buck if you want to beat your rival god. Sometimes that means choosing not to do a miracle to conserve power. This option also can be combined with other options, such as the rival god blocking him, to help explain why it's so costly to do a miracle right now. It's all going according to plan As an all knowing deity he can make plans beyond that of mortal man. With this brilliant knowledge he has made some great plan that involves his faithful loosing this competition. Given the neigh-omnipotence of gods you can get away with any level of convoluted reasons for why the god was convinced not helping his followers would better further his long term plans. It has been prophcied A prophecy from another god or power suggests that this fight will be lost anyways, or that some greater evil will happen if the god gets involved, so the god chooses to stay away. On a particularly jerky god pessimistic version the god made a prophecy to his people in the past and realized it won't come true if he helps here. So he lets his people fail here just so he can brag that his prophecies came true. Basically this is the godly version of a politician being more concerned about looking good politically then making good laws that will benefit their constituents. We're sorry but your god is busy on the other line. Please keep prostrating yourself and he will get back to you as soon as he can. Please know your prayer is important to us. Plenty of works I've seemed have non omnipotent gods, who for all their power can only do so many things at once. In this case they may be distracted or too busy to help their faithful at this moment because another situation has come up. * Your god may be helping faithful in some other part of the world right now, in a more complicated situation that simply needs their intervention more. * Your god may have been intentionally distracted by another god to keep him from being available to help you, or a god may be using some divine power to help hide you from your gods sight so he doesn't notice you need him. * Your god is lazy and was too busy playing in the Divine Games, getting drunk on ambrosia, or sleeping in to bother helping you right now. Have I mentioned yet that many gods were kind of jerks? [Answer] # The material world is too flawed Followers of [Manichaeism](https://en.wikipedia.org/wiki/Manichaeism) believed in > > an elaborate dualistic cosmology describing the struggle between a good, spiritual world of light, and an evil, material world of darkness. Through an ongoing process that takes place in human history, light is gradually removed from the world of matter and returned to the world of light, whence it came. Its beliefs are based on local Mesopotamian religious movements and Gnosticism. It reveres Mani as the final prophet after Zoroaster, Gautama Buddha, and Jesus. > > > As far as I understand it, the Manichaeists believed that material world is inherently flawed and evil, an unintentional byproduct of conflict between a good God and its evil counterpart, the devil (not intentionally created by the benevolent God like in many other religions). The very existence of the material world is thus a bad thing. I'm not sure what they believed about the afterlife, perhaps that souls of the believers would go to the spiritual world of pure light. So for the supreme deity to manifest itself in the corrupt physical world would be just wrong, similar to the Christian God paying a visit to Hell. Even worse actually, since Hell served a purpose, whereas the material world, as far as the Manichaeans believed, had no business of existing at all. [Answer] Two possibilities come to mind The deity is empowered/considers the struggle to be desirable. I think a great example of this is the Mr Wednesday incarnation of Odin in american gods. He's empowered by slaughter, so is fairly happy to let his followers die in combat. Alternately consider Crom from conan the barbarian, who... didn't like being worshipped, respecting struggle and courage instead. Alternatively $deity is disappointed in his/her/their followers. In the 'Last Battle' in the Chronicles of Narnia, Aslan talks about how evil acts in his name were accepted by Tash and vice versa. While the 'mechanics' of worship happen, the 'intent' not being there might annoy the deity. Basically their actual faith is lacking. ]
[Question] [ This question already has answers here: [Visibility in a ringworld atmosphere?](/questions/45087/visibility-in-a-ringworld-atmosphere) (2 answers) Closed 5 years ago. Almost all [illustrations of ringworlds](https://duckduckgo.com/?q=ringworld&ia=images&iax=images) that I've come across tend to show off the shape of the ringworld from the surface. This doesn't seem realistic to me, because the ringworld's radius would probably be so big that the curvature wouldn't be noticeable, especially in the presence of an atmosphere (due to light scattering). One explanation for these portrayals that I can imagine is that maybe an illustrator has no way to represent the ring shape and the fact that it's a habitable world without resorting to some unrealistic visuals. Am I wrong in thinking that the great radius and the light scattering would prevent inhabitants from seeing the ringworld's shape, or is this indeed just artistic license for practical purposes? [Answer] > > Is it really possible to see across a ringworld? > > > Yes, it is. Remember that the world is shaped like a ring, and due to the rotation used to simulate gravity, the atmosphere will mostly be located close to the ring, leaving the center space-level empty. With that in mind, when you look on the other side of the ring the visual rays reaching your eyes actually travel through a thinner layer of air than those coming from an adjacent region. Look at the schematic below (not in scale): [![ring world atmosphere](https://i.stack.imgur.com/fJmFl.jpg)](https://i.stack.imgur.com/fJmFl.jpg) When you look at an object along line of sight B you are actually looking through a larger layer of air than when you are looking along the line of sight C. This means that you will see the image of the ring world fading away where the optical path goes through more air and then becoming sharper. [Answer] For the purpose of illustration let's assume the Ringworld has a radius of 1AU and is as broad as earth is wide, so around 12000km. There are two differen aspects to your question: How does the curvature of the Ring look like from it's surface and how bright is it. Assuming an Earth-like surface we can assume around the same absolute magnitude for a roughly earth-sized segment as for earth. Given that we can see Venus just fine and it is one of the brightest objects in the night sky the ring, which is much bigger should be quite obvious in the night sky (I'm assuming a Niven-style day/night system here where an inner ring with partial segments rotates to block the sun for night time over a part of the Ringworld). You would see a segmented line go right over your head. I don't expect you to see anything during the day though since you can't see Venus either when the sun is up an noon, and on a Ringworld it's always noon or solar eclipse night. As for the curvature near the horizon that's more tricky. With geometry (Thales' theorem is useful here) it's clear that distance of two points on a circle is Diameter times sin(x) where x is the angle between the circle tangent at one point and the secant connecting the two points. So if you're looking at a part of the ringworld the angle x is what you have to look up from your local horizontal. You can see stars even just a couple of degrees over the horizon so we can go deep. At 2° you are looking 35 light seconds away. Earth in that distance would have an angular diameter of about four arc minutes. That's not big, about one sixth of the full moon. So you could see that it has a diameter and probably even some structure if you have good eyes or a primitive telescope. But it's not the big "circle curves in to become your horizon" a lot of ring world illustrations show. Tl,dr: In the dark it should be a bright line going over the sky. But the curvature and nature as a circle only becomes visible at low angles so you could easily imagine people living in regions with hills and low visibility and you could miss the circle nature of the world from there. At an ocean with good conditions it should be obvious though. [Answer] You’d most certainly be able to see the ringworlds shape, and you’d be able to tell that you’re living on one. You can see the moon from earth despite the atmosphere. Maybe the immediate horizon (few hundred miles) might be impossible to see. Im sure someone could science it up and give you a solid answer on distance. However, you would be able to see the ring rise up into the sky (eventually) You’re basically standing on top of a mountain because the ring is curving upwards. No matter where you stand everything is curving away from you. On Earth it curves out of your field of view, but on this ring it curves upwards into your field of view. ]
[Question] [ So, it turns out that bats are actually pretty good swimmers; several species of bats have been reported swimming, and they're far more capable and agile in the water than they are on land: <https://youtu.be/62T-Ht_jWHE> If you think about it, some of the bats' unique evolutionary features could be extremely useful in an aquatic lifestyle. They already possess echolocation which is arguably more refined than, and superior to, that of cetaceans. Bats also have the most efficient respiratory and circulatory systems of any mammals, and their wings enable them to manoeuvre more accurately than birds, and fly more efficiently, with less drag and less energy loss. Bats' Merkel cells also have tactile hairs which allow them to detect and adapt to changing airflow, enabling them to judge the most efficient speeds to fly at, helping them to perform complex manoeuvres to capture prey in flight, and even helping them to sense prey from the disturbances in the air. In the water, Merkel cells could potentially be even more important and advantageous. Shallow torpor and heterothermy would also be extremely useful. And a full aquatic lifestyle would also remedy many of the bats' greatest weaknesses and limiting factors, such as most bats' inability to walk on land, along with their increased levels of respiratory and cutaneous evaporative water loss, which would cease to be an issue in an aquatic environment. Bats have already lost their sweat glands on their wings, and require more fluid intake relative to their body size than any other mammals (including cetaceans), making them highly susceptible to blood urea poisoning if they don't receive enough fluid. The most common cause of death for bats is dehyration, not predation; something that fully aquatic bats wouldn't have to worry about. So, how plausible do you reckon it'd be for a lineage of bats in the future (perhaps the [Noctilionidae](https://en.wikipedia.org/wiki/Bulldog_bat), since they're the world's most amphibious bats at the present time) to evolve to become fully aquatic to the same degree as cetaceans, spending the entirety of their lives in the water and not returning to land at any developmental stage? What do you think that these aquatic bats would look like, and how large could they potentially get- would it be feasible for them to reach or surpass the size of manta rays? And what's the shortest timeframe that you feel such a lineage could plausibly evolve within, from the present day- 5 million years from now? 10, 20, 50? [Answer] In his 1981 book [After Man: A Zoology of the Future](https://en.wikipedia.org/wiki/After_Man), the paleontologist Dougal Dixon postulated that 50 million years hence, semi-aquatic bats would evolve. He called them "surfbats". [![enter image description here](https://i.stack.imgur.com/sQyWD.gif)](https://i.stack.imgur.com/sQyWD.gif) This is a paragraph on the surfbat, typed out from my copy of the book: > > The beaches are home to the packs of surfbats, Remala madipella, which fish in the shallow waters around the coral reefs. Their hind legs, wings and tail flaps have developed into swimming and steering organs and their bodies have become sleek and streamlined. > > > His basic premise was that a chain of islands popped up in the Pacific on a volcanic hotspot, and bats, not birds, were the first to colonize the island. They diversified into a myriad of forms, occupying many niches on the islands he called Batavia. However, these are only semi-aquatic, like pinnipeds. They come ashore to rest, breed, nurse and give birth. Nevertheless, I know of another speculation on future aquatic bats. These are two screenshots I cropped from the picture "[TFiF: Bats, the titans and the tiniest](https://dragonthunders.deviantart.com/art/TFiF-Bats-the-titans-and-the-tiniest-601287511)". It was drawn by Fabio Alejandro, known as Dragonthunders on Deviantart and the speculative evolution forums. [![enter image description here](https://i.stack.imgur.com/f9FHm.png)](https://i.stack.imgur.com/f9FHm.png) [![enter image description here](https://i.stack.imgur.com/6jnhH.png)](https://i.stack.imgur.com/6jnhH.png) These are future descendants of bats belonging to the family Figocetes, the genera shown being Massobrachypterus and Eosicnidus. Here is what he writes about Figocetes: > > This clade Icaroptera specialized to inhabit the aquatic environment, in the same way as its predecessor’s the cetaceans, changing all their morphology. Descended from semiaquatic clades that inhabit the rivers and lakes of South America, expanded outside the continent and managed to colonize much of the ocean, however, they have failed to compete with several new marine tetrapod descendants of tegus and even other aquatic mammals, so are limited in length and diversity, however, they have been able to find their place in the planet's waters. > > > Alejandro's project, [The Future is Far](http://s1.zetaboards.com/Conceptual_Evolution/topic/5852714/1/), chronicles the evolution of life from 12 million years hence to 1 billion years hence. In his scenario, the bats became one of the most diverse mammal clades on the planet, eventually losing their wings and taking on a plethora of bizarre forms. [Answer] Evolutive convergence would make them not so dissimilar from penguins or dolphins: hydrodynamic profile, short and fin shaped limbs. Under water the membrane they presently use for flying is too flimsy, so it will be quickly replaced by something more suited. Also echo location would need to adapt to the new environment, but that is what dolphins already have. Also size should increase: water is more effective than air at subtracting heat from the body, and small, mouse size bats would have a hard time controlling their temperature with a small body. Considering that whales and similar water mammals have evolved into the past 50 million years, I envision a similar time span for their evolution. ]
[Question] [ I'm writing a fantasy novel and in it I'm designing a huge wooden ship moved by sail and man powered wheel paddle, and I wonder if it would be possible for the ship to carry a ballista inside that fires from the ship's prow? How effective were balistas against ships hull? How powerful was the largest ballista ever known? Sorry for the many questions and thanks in advance. [Answer] Is it possible, inside? Sure, many ships actually [did carry ballistae](https://books.google.com/books?dq=ship-borne+ballista&ei=uK2OVaT1Ocnq-AGNo4L4Ag&hl=en&id=iH4j8abhD1cC&lpg=PA21&ots=bGKGJGFhfO&pg=PA21&sa=X&sig=xrxBLPVsP8B45Io397zbN1XUOpA&source=bl&ved=0CDEQ6AEwAw#v=onepage&q=ship-borne%20ballista&f=false), though those were normally on the deck rather than inside, but inside is still a deck, just means it's a covered deck. But on the top deck rather than a lower deck you potentially have a full three hundred and sixty degrees which you can target by just swiveling your ballista without having to change course & swing the whole boat about, so it seems a bit silly to put it below decks if you only have the one ballista. If you're using multiple small ballistae it makes more sense to follow the pattern adopted by cannon bearing ships, rank them along the sides so you can bring more of them to bear on a single target simultaneously. [Answer] In classical times, Roman ships carried torsion powered catapults as their primary weapon. Roman warships evolved to become larger and have broader beams in order to become stable fire platforms for these weapons, but this may have been co evolution due to the Roman idea of using Marines to board enemy ships: lager ships could also hold more troops, and would also be more stable if a boarding platform like a [Corvus](https://infogalactic.com/info/Corvus_(boarding_device)) was mounted. [![enter image description here](https://i.stack.imgur.com/OXZt6.png)](https://i.stack.imgur.com/OXZt6.png) Diagram of a Corvus\* [![enter image description here](https://i.stack.imgur.com/k7Q9n.jpg)](https://i.stack.imgur.com/k7Q9n.jpg) Ancient Greek trireme. The ship is the weapon [![enter image description here](https://i.stack.imgur.com/jKqSy.jpg)](https://i.stack.imgur.com/jKqSy.jpg) Roman "[Decres](http://www.naval-encyclopedia.com/hellenistic-ships/)". You can see the huge increase in size and provision for catapults on the deck. The smaller "[Liburna](https://infogalactic.com/info/Liburna)" became the mainstay of the fleet after the Romans cleared the seas of pirates, and had no significant opposition This leads to an important question in your worldbuilding: why does your navy feel the need for such large ships? What advantage do larger, more expensive, ships offer which smaller, cheaper ships do not? As an example, the Venetian "Arsenal" had several large "[Galleasses](https://infogalactic.com/info/Galleass)" which were converted into mobile artillery platforms for the [Battle of Lepanto](https://infogalactic.com/info/Battle_of_Lepanto). The Venetian merchant fleet had no use for them as the expense of running them ate any profits they might achieve, and the Venetian navy was dubious about their utility due to their size and slowness. Their use as artillery platforms was fortuitous, since there were only six, and indeed they were so slow they only were able to participate in the opening phase of the battle. [![enter image description here](https://i.stack.imgur.com/l6N5Y.jpg)](https://i.stack.imgur.com/l6N5Y.jpg) Model of a Venetian Galleasses So while your ship seems to be possible in theory, what practical use does it serve which cannot be carried out by smaller, cheaper ships? The polity which owns the ship or creates the navy will be very keen to find the cheapest, most practical means of carrying out the task, and if there are suitable alternatives, then they will take them over the larger, more costly ship. [Answer] > > How powerful was the largest ballista ever known? > > > According to Vitrubius (On Architecture, X, 11), the largest Roman ballistae fired stones of 250 pounds. A catapult this size is an awful idea in a ship: with so much weight it probably took half an hour to fire each shot. It isn't a serious problem in a siege but, since the attack speed of a warship was 8-10 knots, you might want to settle for smaller siege equipment. I think the standard ballista in a Roman ship shot stones of 40 pounds at distances inferior to 400 yards. > > How effective were balistas against ships hull? > > > They weren't designed for breaching the hull (for that they rammed the ship or broke her oars). They were for killing the sailors on board, which is the reason javelins were also used as ammo for ballistae in ships according to Julius Caesar. There were around 100-120 soldiers on a warship, so killing a score of them with some shots was very effective for morale. ]
[Question] [ I've been reading [this question about agriculture for merfolk](https://worldbuilding.stackexchange.com/questions/59132/how-do-merfolk-develop-agriculture) and more specifically the accepted answer. They mention the problem of food preservation only minutely. Now I'd like to pour that thought into a question proper: How would an aquatic species store and preserve food? Let's assume that the main food sources are fish, followed by kelp/seaweeds and shellfish. Some ideas I had myself, but they don't touch on storage or may have flaws I'm missing: * As the comments on the linked question discuss: somehow cure the meats using heat vents. Perhaps use air bubbles to keep dry? * Do as some prehistoric gatherers did: simply store meats in a location with a very cool flow of water which supposedly slows down decay. [Answer] Storing and preserving food should be one of the easier tasks for merfolk. There are some places undersea that are excellent environments for preserving organic matter. For example, cold, low oxygen [parts of the bottom of the Black Sea,](http://news.nationalgeographic.com/2016/10/black-sea-shipwreck-discovery/) Per National Geographic: > > In most seawater, wood and rope are among the first things to decay. > But the unusual water chemistry of the Black Sea dramatically slows > rates of disintegration. Many of the shipwrecks that Adams and his > team found were in depths below 150 meters, and some lay as deep as > 2,200 meters below the surface. > > > The wood of some ships was so well-preserved that chisel and tool > marks were still visible on individual planks. Rigging materials, > coils of rope, tills, rudders, and even carved wooden decorative > elements have survived the centuries largely intact. > > > “Nobody has seen anything quite like this before,” Adams says. While > historical texts and illustrations give some information about the > appearance and construction methods of merchant ships in different > periods, Adams hopes the extraordinary preservation of these wrecks > will allow archaeologists to independently verify those historical > records. > > > British and Irish bogs and similar, muddy, shallow water, low oxygen environments are also good place for preservation of food. Researches have recently recovered [3000 year old butter stashes](http://bellbeakerblogger.blogspot.com/2016/09/i-cant-believe-its-not-butter-nordic.html) in these bogs. At that point it isn't yummy, but it is still edible. There is a picture of it below: [![enter image description here](https://i.stack.imgur.com/zCC3i.jpg)](https://i.stack.imgur.com/zCC3i.jpg) [Honey](http://www.smithsonianmag.com/ist/?next=/science-nature/the-science-behind-honeys-eternal-shelf-life-1218690/) can also make an excellent long term preservative (also [thousands of years](https://books.google.com/books?id=vCqoog8WH3gC&pg=PA122&dq=honey,%20egyptian%20tombs,%20unspoiled&hl=en&sa=X&ei=81AWUoLAF6654APig4HgBg&ved=0CDkQ6AEwAg#v=onepage&q=honey%2C%20egyptian%20tombs%2C%20unspoiled&f=false)) and being underwater where it is cool, protected from light and is protected from bears and insects and people who like to raid and eat it (sea animals don't seem to have as much of a sweet tooth as land animals do), are all a good fit. Obviously, the merfolk couldn't make honey themselves underwater, but this could be something that the desire as a trade good in exchange for something else. And, of course, don't forget one of the most common premodern preservatives, which is salt: [salt meat](https://en.wikipedia.org/wiki/Salt-cured_meat) including beef and fish are some of the oldest foods with long shelf lives and the oceans have an abundance of salt. > > Salting, either with dry salt or brine, was a common method of > preserving meat until the 19th century. It was frequently called > "junk" or "salt horse". > > > Salt inhibits the growth of microorganisms by drawing water out of > microbial cells through osmosis. Concentrations of salt up to 20% are > required to kill most species of unwanted bacteria. Smoking, often > used in the process of curing meat, adds chemicals to the surface of > meat that reduce the concentration of salt required. > > > Salted meat and fish are a staple of the diet in North Africa, > Southern China, Scandinavia, coastal Russia, and in the Arctic. Salted > meat was a staple of the mariner's diet in the Age of Sail. It was > stored in barrels, and often had to last for months spent out of sight > of land. The basic Royal Navy diet consisted of salted beef, salted > pork, ship's biscuit, and oatmeal, supplemented with smaller > quantities of peas, cheese and butter. Even in 1938, Eric Newby found > the diet on the tall ship Moshulu to consist almost entirely of salted > meat. Moshulu's lack of refrigeration left little choice as the ship > made voyages which could exceed 100 days passage between ports. > > > [![enter image description here](https://i.stack.imgur.com/MJ5wx.jpg)](https://i.stack.imgur.com/MJ5wx.jpg) Salt Fish hanging in a Hong Kong market in 2011 via Wikipedia @John also has a good point about live storage. Most Asian grocery stores in the U.S. sell very fresh fish and seafood by having at least some varieties live in tanks in their stores until it is purchased, and this would be a natural approach for merfolk. [![enter image description here](https://i.stack.imgur.com/jHveY.jpg)](https://i.stack.imgur.com/jHveY.jpg) Live lobster storage as a grocery store via Wikipedia [Answer] # Pickling From wikipedia: > > Pickling is the process of preserving or expanding the lifespan of > food by either anaerobic fermentation in brine... > > > The rest is just academic. You can pickle things by soaking them in brine. So pretty much everything that merfolk are going to eat is going to be at least a little bit pickled. Any developing merfolk society is going to probably start from pickling and develop other food preservation methods from there. Vinegar is an obvious next step, since that is the other main component of pickling. Vinegar is produced by bacteria fermenting foods, so there is no reason it would not work underwater. The challenge would be to make a watertight container that you could put your fermentation materials, along with seawater, to let the bacteria do its work. Once you have a container full of vinegar, you could use a hand pump to move it to another container with things that you want to pickle. Conceptually, it seems hard to think of a good way to transfer liquids between containers while immersed in another liquid, but I have confidence that merfolk growing up in such conditions will have more imagination. The list of things you can pickle is long, but importantly, contains both fish (delicious pickled herring) and seaweed (like Japanese su kombu). [Answer] live storage is always an option, cages would let shellfish feed until you are ready to eat them, they work fairly well for fish too. canning/jarring would still work but they would need to get those things and would need to use deep sea vents to cook them. [Answer] Come up with an algae, or kelp, or the skin of a particular fish. Something that has antibiotic, or whatever, properties and a relative large surface, and have your merfolk wrap packets of food with it. ]
[Question] [ Much effort went into creating sims, uploaded personalities obtained through destructive scanning of a person's brain. These efforts have largely been successful. Whilst officially banned in the civilized world, the practice has gained significant currency, and terminally ill rich people now routinely travel to [Transnistria](https://en.wikipedia.org/wiki/Transnistria), where you can still buy bullets by the bucket, semi-sentient anti-aircraft missiles, and yes, get a (sometimes dubious quality) mind upload done with no legal hassles. The Sims are passing the Turing test with no issues, and for the most part (save for the occasional abomination), sound indistinguishable to living friends and relatives from the original. Increasingly, the sims are fighting to gain legal recognition as "Remnanters" - legal successors of the dead Person they used to be. However, problems soon crop up in dealing with identity. One can (and sometimes does) create multiple copies of the same uploaded personality. So Richie Rich travels to Transnistria, gets their brain "read" and creates a Richie Remnanter A, who is placed in an android body and walks the Earth again. A different version of Richie Rich, Richie Remnanter B, chooses to stay in a virtual environment running at 10x real-life speed. I have thought of 3 approaches: 1. Remnanter A and Remnanter B are now different persons and diverge exponentially from here on. This is the default path, but leaves thorny legal issues, such as which Remnanter gets control of what portion of assets. 2. Somehow, only one Remnanter is allowed. This would be hard to implement technologically, especially with ruthless Romanian and Russian hackers and bio-engineers in charge. 3. Remnanter A and Remnanter B occasionally sync up, creating a unified personality with multiple presences. This seems hugely technologically challenging, even more so if we want a (near-)continuous sync. Which one of these (if any) is most likely to be the preferred path, and why? If you think another outcome is more likely, I would like to hear it instead. > > Why Sims? It turns out that creating non-insane AIs is hard. In retrospect, AI research historians suggest, it should have been obvious that the possible [Hilbert space](https://en.wikipedia.org/wiki/Hilbert_space) of insane dysfunctional minds is much, much larger than the space of sane minds, and without the finely tuned evolutionary help of millions of subjective years of evolution, one is highly unlikely to stumble into the sane space. Programming AI from scratch has thus proven impossible. > > > [Answer] I'll leave the final choice up to you, but this is what I envision for each choice: ## Path 1 As information changes, it becomes different; even if a human were cloned, memories and all, the 'new human' and the 'old human' would rapidly begin to differ. Belongings are left to the first copy to claim them; the android is the first system online, and thus would get all the belongings. Future copies are left with nothing and treated as new beings. ## Path 2 The human brain isn't a computer; while it's possible to destructively copy (aka move) the contents to a digital version, at no point in time does the personality become fully information. These special digital brains are still physical objects, and the only way to copy a brain is by destroying the original, be it digital or organic. An android would have the brain stuck inside it; a "software only" version would simply hook the digital brain up to a computer. While it's possible to make a non-destructive copy, the result is only superficially similar. Anyone comparing the brainwave signature of the bad copy to the original human or to the digital copy would instantly see they were different. ## Path 3 Once uploaded, a human mind will realize just how easy it is to make copies of itself. Splits and merges become commonplace; androids become rent-a-bodies, to deal with the physical world. To sync, two minds merge, then make a copy to "split". Each mind has its own signature, a unique key. When two copies of a single mind merge, the signature remains the same, but if two different minds merge, they create a new signature, a child mind, an equal merge between the two. Belongings are shared equally between the minds of a given signature. Essentially, any cluster of minds with the same signature are considered a single collective being. [Answer] Path 3 if it's possible. Since the Remnanter's are basically data, and since sharing data is what computers do, the only really tricky part for syncing them up is figuring out what format to put the data in. The data could be streamed through a cloud share and be near instantaneous. A kind of Remnanter Beowulf cluster. On an interesting side note, you could achieve speed of light travel this way. Richie Remnanter needs to travel to Mars. It hires an android body on Mars, and transmits a copy of itself to the receiver on Mars which transfers it to that body. After the mission is completed all data is transmitted back, and Richie Remnanter on Mars either continues on to do other things, syncing up on occasion, or deletes itself, whichever they decide. Otherwise path 1. I would do it like this. Richie Remnanter A is the original version created from the brain. It descides to make a copy, Richie Remnanter B. Legally Richie Remnanter B would be the child of Richie Remnanter A. In making the copy, Richie Remnanter A takes on the legal responsibility of making sure that Richie Remnanter B is taken care of, and Richie Remnanter B can inherit if Richie Remnanter A is deleted, but Richie Remnanter A gets to keep control of all it's assets. Legally, Richie Remnanter B could accept an allowance/paycheck from Richie Remnanter A, possibly for doing the work that Richie Remnanter A duplicated it for, or it could decide to go off on it's own and make it's own way in the world. If Richie Remnanter B decides to duplicate itself to Richie Remnanter B.2, then it has it's own legal responsibility to it, and Richie Remnanter A does not. IMHO, Path's 1 and 3 are not mutually exclusive. Path 2 Is problematic, as if history has shown us one thing, it's that once something is data it can and will be copied. Maybe if it had to be run on a quantum computer and copying it destroyed it? But someone would find a way. Once you can copy the state from a living brain, copying the state from a computer is kind of anti-climatic. [Answer] I'd go with Path 1. A standard for Remnanters can include an exposed hash (that's of significant size), or perhaps one prepended to a hash identifier of the DNA of the original human. You could conceivably run into collisions of identity with help from the Birthday Paradox, but it wouldn't be unlike the edge case issues we run into today with DNA (chimeraism) and fingerprints (removed, duplicates, etc.) The hashes would be generated upon creation of the Remnanter, and could be registered in the same way that humans are with social security numbers and what not. Once you have a standard in place, you can identify a Remnanter. International law can require that the standard be implemented as a sort of contract in order to be considered an owner of personhood, or whatever is necessary for inheritance or legal recognition. So if a rogue system decides to create Remnanters that don't implement the contract, then they're the same as our modern rogue systems who say, cut off their fingerprints, or operate in the shadows with physical cash currency. It would be hard for them to operate and be welcomed in society that's expecting an identity and cooperation with the laws in place. One might be able to duplicate another Remnanter's identifier, but a registration to a database and some secondary pieces of information can help with that. It would be no different to how we fight identity theft, or add chips to our credit cards for fraud prevention. I find this to be less problematic than paths 2 and 3 because they require a lot more technological finesse and don't have a lot of correlaries with modern society like path 1 does. [Answer] Path 2 would not be my choice, but as a defender of lost cause I would like to make it a slightly better candidate so that it falls back in the race. In particular, you insist on the destructive scanning of the brain required to build a sim. If the destructive part is not a technical choice, but a fundamental issue because the reading require to be quantum-precise and breaks the original, then this option is the only viable one. Some theories relate consciousness and quantum physics. I do not buy it but it gives credibility to the scenario. And you could still have fun by mixing sims : like having half of the memory of A and half of the memory of B, and the emotions of C (and you would be able to tell what part of us depend of our memories, btw.). Damn russian hackers ! [Answer] I prefer path 1. Add a unique identifier to the code of each remnanter from a person, to disambiguate them. The original person should have made provisos for inheritance, or the law should state that all remnants share the original's fortune. Further splitting and merging of remnanters would create new remnanters, who could inherit from the ones from which they were created. Since AIs are, effectively, immortal (alive as long there's computer support), inheritance laws would need to change: can an immortal's child inherit anything from its father, with him still alive? [Answer] Path 4: Inheritance becomes an obsolete concept as mankind becomes semi-immortal. Inheritance in the real world is governed largely by culture, and stems from the fact that people die, and then there's stuff left behind that used to be there's. The solutions to the problem of what to do with that stuff are as varied as the breadth of human cultural experience, with a particularly common option being that the firstborn son gets everything (with lots of fiddly bits if there isn't one of the appropriate age). However, modern egalitarianism combined with western tradition has lead to a state of affairs in much of the world where default inheritance can and is frequently overridden by an explicit Last Will and Testament. While subject to different laws and stipulations, a Will is nonetheless effectively a sort of gift on the part of the dying to some number of successors. Because death is so frequent, these kinds of gifts are also very frequent and have grown a lot of culture around them. Without death to keep inheritance at the forefront of the minds of the populace, and with tricky bits to sort out if the institution is kept around, and with growing widespread distaste for the kinds of inequality fostered by large inheritances, it seems likely that the institution would not stay around long. One solution that seems likely is that governments would just lay blanket legal claim to the possessions of any person who is rendered dead. Another solution, less likely because of humanity's multimillennial obsession with death, would be that people just don't deal with the stuff belonging to dead people and it gets sorted out the same way as stuff that's abandoned, since death becomes so rare. ]
[Question] [ Suppose human race in its current state disappears at once, every human being, leaving everything the humanity has created. All the other forms of life remain. * How long will the civilization traces still be detectable by another civilization which accidentally comes to the Earth? What if it has technical progress level same to ours and what if they have much more advanced technologies? * What are the traces of our civilization which will remain detectable longest? Will it be spacecrafts on the orbit? And what apart of them? By detectable let's mean state of an object which allows one to say for sure that it's been created by intelligent civilization. [Answer] ## Billions of years. Future visitors will find rock strata with clear signs of the [Anthropocene](https://en.m.wikipedia.org/wiki/Anthropocene) epoch. It will contain novel minerals that incorporate plastics, glass, and other refined materials. Further detailed searches will locate fossils. Even if a car, for example, has been competely eroded, it will show traces of the metal shell that was originally burried in the mud. Organic matter will rot but synthetic polymer will not, and will be encapsulated: larger samples can be found with enough effort. > > Increases in erosion due to farming and other operations will be reflected by changes in sediment composition and increases in deposition rates elsewhere. In land areas with a depositional regime, engineered structures will tend to be buried and preserved, along with litter and debris. Changes in biodiversity will also be reflected as will species introductions. Litter and debris thrown from boats or carried by rivers and creeks will accumulate in the marine environment, particularly in coastal areas. > > > Then there are the footprints and [machines on the moon](https://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html), which will have a datable thickness of dust coving everything. So I have to say that as long as the Earth exists, our imprint will remain detectable. That will be about 5 billion more years, before the final great recycling. [Answer] This depends on which structures created by the humans are left standing. We are talking about cities here. Skyscrappers. Mills, factories, production units. Libraries. How many (and in which condition) of these are standing? And where, too? Long after the human race (I'm counting 50,000 years here) is extinct, an alien spaceship lands on earth. Even after 50,000 years of storms, cyclones, rainfalls, scorching heat, meteorite impact events and earthquakes, you would be amazed to know how much of our current structures would be immediately detectable. Not detectable as in "oh wah! look this is the statue of liberty!" but as in "here are some fragments of a large figurine. most parts are missing but here is the right foot and some portion of the left shoulder." With dating methods, they can easily date the remains and know that an advanced intelligent race dwelled on this planet nearly 50,000 years ago. They could excavate a museum and find some fragmentary pieces of earlier civilizations which would date to 55,000 years or so (egyptians). In regions where fossilization conditions are favorable, they might excavate human skulls and limbs and form a good understanding of our anatomy. This is if the alien civilization was smart enough and was technically advanced enough (nearly our level with 10% margin). --- If they don't have any dating methods available, then they can definitely deduce that a very advanced (they don't know dating techs so definitely our current tech progress is greater than theirs when they land) race used to live on this planet. But they will not be able to deduce when they went extinct. [Answer] Millions, or Possibly Billions of Years. Air, water, and tectonics will eventually devour everything left on the face of the earth, and I suspect that anything in LEO will eventually fall out of orbit due to drag from the attenuated atmosphere. That said, we have left a whole lot of junk lying around on the moon, some of it surrounded by hundreds of human footprints. With no atmosphere to speak of, that junk could last a long time. For bonus points, you could have your hypothetical aliens notice light bouncing off one of the [retroflective mirrors](https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment) we left behind. The folks at space.com seem to think that [the moon will last until the sun changes into a red giant](http://www.space.com/3373-earth-moon-destined-disintegrate.html). This gives you an upper bound of [5.4 billion years](http://www.universetoday.com/18847/life-of-the-sun/). By that point, however, all the other life on earth will likely be gone as well. A more reasonable upper limit may be far less, however. The sun will get really hot in another 1.1 billion years (see prior link), and we don't really have any long-term data on the effects of unshielded exposure to the solar wind. Still, I think a few million years would be a safe bet, and even if you can't figure out where it came from, evidence of space travel would seem to imply "civilization" of some sort. [Answer] Buildings will remain, at least as traces. there's [a nice documentary on that](https://en.wikipedia.org/wiki/Life_After_People), you should take a look at it. As far as I remember, it didn't consider the most valuable part of our civilization anyway. From the information point of view, our culture is doomed for the most part. Books are perishable, in a geological time scale. Depending on the material, they will last from 10 to 10000 years. Even more CDs, DVDs, hard drives. in about 100 years or so, all of these data media will disintegrate. what will be left? clay tablets, epigraphs, and anything that is written on resistent materials. There are many examples, some of these are very surprising, but very rare. look for Jordan\_Lead\_Codices on wiki. If aliens, or even future humans from 30k years in the future would find these, what they could understand? we are still having troubles understanding [many dead languages which left some kind sort of written corpus](https://en.wikipedia.org/wiki/Undeciphered_writing_systems). Another point of view is, what if the only things that will remain of our civilization relate to just one aspect? Egyptians in example, didn't build their homes with stone, not even the palaces for the most part. So we only know about them through their tombs and some religious monument. What would aliens know of us if, in example, only military bunkers and research facilities deep underground would remain? ]
[Question] [ I've been thinking about a cyberpunk universe where nanobots are a universal force capable of achieving many things, examples include: * Biological and medical modifications of the human body * Construct/reconstruction of machinery or infrastructure and general maintenance * Combat, war, etc where nanobots are used to shutdown weapons and vehicles or simply consume attackers These examples are fairly extreme and probably wouldn't be frequent in the universe but I'm interested in the physics of nanobot consumption. Say a particular species of nanobot is developed. How would it 'consume' objects and what would it do with the matter after if consumed it? I'm interested specifically in the functionality of the nanobot and any side affects that functionality might have. An example of a silly non-realistic answer might be: It uses a little pacman mouth to devour atoms.... [Answer] You should not think of a nanobot like a 'eating'-animal or something. This would be a big problem, due they only could handle molecules and cells wich are smaller than they are, plus they need additional size for some extracting or cutting mechanics to get the molecules/cells off whatever they're attached to. Better think of nanobots like enzymes. They could attach molecules and bring them to react in some chemical way. For example, they could change the connections of atoms in molecules to extract specific atoms and transform the molecules in that way. Think in chain-reaction. If I cut off a hydrogen of H2O what would happen? Depends on the environment, but one possibility is that the left over HO will react with another leftover HO to H2O2 Hydrogen peroxide which is very corrosive and will damage the environment. (An example of Nanobot-weapon). This is a very simple molecule. What would happen with DNA for example? You could change the creature's DNA that way! Just change a big amount of the stem cells. You may also think of it in some kind of virus. If it's able to alter metabolism (just as an enzyme) and also to nest in a cell, it could alter the behavior of the cell like a parasite. What would be happen if a nanobot could change the way a specific nerve cell works? It could alter the behavior of his host creature for example. You also could change the production of some hormones. But to harm the host is not the only possible usage. Nanobots could be used as a guardian to protect the host against other nanobots, viruses, bacteria and so on. They could close the bloodstream very fast after a injury, be used as storage for adrenaline, ATP and so on to make a fighter fight better for longer time without getting tired. If small enough and working like enzymes which can nest cells, nanobots simply could imitate and alter every part of the metabolism. In either, good and bad way. EDIT - additional thoughts from comments: How to keep em small: One kind of bot for one kind of job! Like in programming, the more a function does, the larger it gets. So if a nanobot has to cut and assamble different kind of molecules, it needs several tools. You could make one specific bot for cuttung, one for assambling and so on. This makes them smaller. Communication to outside: There a two ways of possible communication: Hard-wired, and radio. "Hard-wired", not to take literally, could be mady by a docking-station in the skin or something. When the bots visit the dockingstation, they get the last received order which is saved in the dockingstation. "radio" gives the big disadvantage, that a receiving bot must be pretty large (antenna). But if you take the same concept as in hard-wired, it's not a real problem at all. Make a few specific nanobots that have an antenna and put them into venes or hollow organes. They do not have to move, so they could be >1cm long and be able to receive radio signals. Other bots go to the "receiver" bot to get their orders. Both concept raise the problem of slow reaction, due they only know the last order they have taken and do not know if a new one arised. This problem could be solved with this concept: Inner communication: Do you know how white corpuscles know where to go? Due hormones and stuff. Your nanobots could communicate with each other if they release some specific molecules. Other bots, which notice it, have a protocoll how to react to specific concentration of this pseudohormones. That way, a nanobot could tell his little friends that a new order is in, or that he needs help with a specific task. [Answer] ## Grey goo A nanobot can't consume matter in the way we do, unless we provide it with a little stomach. A classic nanobot has atomic scale manipulators capable of grasping and moving individual atoms or molecules. If a group of nanobots wanted to break down an object, they would likely sort the individual atoms into a soup of reusable components. This might take the form of a ["grey goo"](http://en.wikipedia.org/wiki/Grey_goo), or possibly a solid block of matter if space were at a premium. This would contain the same atoms as the original object, just stacked more efficiently. If they wanted to remove an object from the picture altogether they might convert it to a gas or atomic scale powder and allow the components to simply float away. ## Intelligence There's nothing to stop nanobots from containing simple computing devices. Presumably they would be networked and the intelligence would reside in the collective, similar to an ant colony or bees nest. ]
[Question] [ We once lived in a galaxy filled with the wonders of technology indistinguishable from magic. Even the poorest beggar could afford this mass-produced tech. Vidscreens as real as life, longevity infusions and the occasional passage on an FTL ship. But then there was the Fall. Worlds died in torrents of violet flame, and the knowledge of Humanity was lost forever. The galaxy is less spectacular now, but some can still afford these marvels of technology. My question is: how? I want a world where pretty advanced technology is rare, but existent. Specifically, I want it to be made and repaired only by lone craftsmen or small collectives. So what conditions are necessary such that advanced technology can be crafted, but not mass-produced? [Answer] Easy - magic (as the question states in its first sentence). Not real magic, but science and knowledge lost to the majority, such that high technology devices can only be constructed by those indoctrinated into the magical arts and taught, not just how to mechanically construct these devices, but how to infuse them with the necessary 'magic' to make them work. A culture which would prize, revere, but also fear such arts, to the extent that the population would not wish to tamper with or investigate such devices too closely. The occasional accident, e.g. electrocution, might easily reinforce this. Once this is culturally the province of 'magicians', there will be a natural inclination to leave it to that order. The 'magicians', of course, will have a vested interest in keeping it that way. The fact that this 'magic' is actually science would be irrelevant, because science would be lost to the majority of people and 'magic' a much easier way of understanding and explaining (you don't have to think too hard about it). Very few people actually understand how much of modern technology works, anyway. If we take away the concept of 'science', we are left with 'magic'. To be honest, I'm not too sure that we are very far away from that kind of scenario, today. [Answer] A key material was lost Building on @Andon's answer: The ability to aquire or manipulate any material upon which the tech is dependent is lost in the Fall. Be it antimatter, "duranium", or any other form of [unobtainium](https://en.wikipedia.org/wiki/Unobtainium). As @AngelPray suggests in his/her comment, this forces present-day people to scavange pre-Fall equipment for material or puts a lot of power in the planets or facilities that can produce the element. For example, planets that were the source for this material may have been destroyed in the Fall or the records to locate them lost. Smelting or other processing might have been concentrated in a couple of systems and were destroyed. This leaves a precious few places to get the materials and only a few places that can process it. A key transportation technology was lost People can still get around in smaller ships, but the tech to build the big super-tanker/freight ships is gone. "Mass produced" on a galactic scale is breath-taking. Consider for a moment just how many tons of wheat is needed to feed one good sized city for only one day. [According to the USDA](https://www.ers.usda.gov/topics/crops/wheat/wheats-role-in-the-us-diet/), the average U.S. citizen ate 132.5# of wheat annually in 2011. That doesn't sound like much, only a bit more than 1/3# per day. BUT, the population of LA in 2011 was 3.8 million people. That was 1.38 MILLION pounds of wheat DAILY. Generally, a semi-trailer can haul 55,000#, so we're talking just 25 truckloads a day (people who know about shipping are wondering at that cavelier statement). Now let's assume something stops diesel semi-tractors from working and all we have to work with are 1/2-ton pickups. Suddenly we need 1,380 truckloads, plus drivers, plus the congestion it causes, plus the hassle of loading and unloading.... The loss of those interstellar super-freighters all but shut down the ability to transport the mass-produced products to all the worlds, leaving access to parts and products in the hands of a few entrepenuers who can handle the load for people who can pay the prices. The economy is in ruins Back in 2014 there was a shortage of .22 calibre ammunition. There were a lot of reasons for the shortage, but the point I'm making is, why didn't somebody take advantage of the higher prices to fire up another plant? Wouldn't they have made their money back? The simple answer to a complicated problem is "no." The cost of building an entire new manufacturing facility is really, really, really high. So, if your means of mass production was destroyed during the Fall, you can't just bang it all back together. Just the cost of cleaning up the rubble is prohibitive. Look how long it took to clean up Europe after WWII. This is likely the easiest reason why you don't have access to the mass-produced items anymore. The factories and manufacturing plants are gone, and no one can afford to rebuild them yet. This leaves small manufacturing facilities with severely limited distribution. Employee shortages And that assumes that you still have the people to staff those centers. I assume people died in the Fall. Most planets will be desperate to keep employees in jobs that feed, house, and protect local populations. Who cares if anybody wants an intragalactic radio? Breakfast is much more important! The government might spare a handful of people to build/repair the toys congressmen depend on to look important... but only that handful can be spared! When trade is cheap, information is power. When trade is expensive, trade is power. Massive ruination like the Fall inevitably shifts power. Beforehand, most of the power was probably in the hands of interstellar corporations... but those corporatations were gutted during the fall. Most were destroyed as symbols of tyranny and the rest were annexed by local governments as critical resources to protect local economies. This distributes the power massively, and now the little guy once again has the ability to exert his/her influence! With the big corporations gone (and, more importantly, their legal departments gone with them), small mom-and-pop shops building and selling cool tech are popping up all over the place. They can't produce anywhere near what the big corps could... but what they produce is amazing! Because innovation didn't die with the Fall. If anything, necessity breeds invention, and the Fall is actually responsible for thousands of wonderous new products ... that almost no one can obtain 'cause there's only so much stuff you can fit in the back of a proverbial 1/2-ton trade ship. [Answer] > > "Any sufficiently advanced technology is indistinguishable from magic." ~ Arthur C Clarke > > > Much of the technology from before the fall still works, but people have no idea how it works. Some simpler devices or parts of them are manufactured by blindly copying existing ones, possibly by small groups that horde the secrets of how they do it. Some more can be repaired if damaged but cannot be built. Others are unique and irreplaceable. For example take a Laser Rifle where all three things might be true at once. * They know how to make chargers - by copying existing chargers. * They can repair or replace basic attachments like the handle * But if the focusing and energy generation crystals inside are ever damaged the rifle becomes unusable. [Answer] This answer is a sci-fi trope in itself: Antimatter Pre-Fall technology relied on antimatter power. The containment systems were incredibly advanced - And very, very stable and reliable. But part of that reliability is that they safely "vent" miniscule amounts of antimatter over time, so almost all of the pre-Fall antimatter storage containers are empty. They are moderately common, but in incredible demand so they're not cheap. The technology to replicate them is unknown. Current technology can refuel these antimatter storage facilities, but it is a tedious and slow process. Where Pre-Fall facilities could produce antimatter in spades, current facilities are only capable of trickle-charging the antimatter containers. Keeping these facilities functional and safe requires significant investment. I view this as less of a production issue, and more of a fuel-rate issue. Even if you have a million gallons of gasoline, it'll still take forever to fill your car if the only method you have is transporting it across a road via shot glass. For the rest of the technology, it's also a bit of scavenging and rebuilding things. Some is easier to fix than others, but almost all of it requires absurd amounts of power. While you can build a huge number of modern reactors to power it, it's far easier to just run an antimatter supply. [Answer] A basic lack of resources. Well before the fall necessary resources had been used up in "nearby", easily reachable, worlds causing them to go farther and farther from civilized space to get them. After the fall, the only places those resources can be acquired are far from "known" space. Small civilizations or clans may still have the tech because they have passed down the knowledge of where to get the materials to make it, or perhaps secured a pre-fall facility of their own with information (processes, procedures, materials, locations, etc) known only to them. [Answer] Cultural appreciation for craftsmanship. If consumers prefer to buy items that were made by hand with a "personal" touch, then that is what will be produced. Similarly, if consumers come to believe that mass-produced items are somehow inferior, then mass-produced items will not sell, and people will stop making them. This all assumes that you have a free-market structure in place. ]
[Question] [ OK, let’s suppose I have a structurally sound ship—it could take a shaking—and that space debris isn’t a problem. I have access to a high level fusion reactor, which can, for all intents and purposes, output a near-unlimited amount of electrical energy. The humans of my world have developed artificial gravity. Could they use this type of technology, combined with their massive energy source, to theoretically warp the space in front of their ship in an imitation of a large body of mass, basically creating a gravity well that consistently remains in front of the spaceship, “sucking” it forward? About how far outside the realm of plausible physics do you think this lies? [Answer] If you could create a perpetual acceleration due to gravity using energy (matter-antimatter reactors would be better for this), it would be like falling towards a planet that is always moving away from you. This is different from the Alcubierre Warp Drive because the sip is being dragged through space. Your gravity drive might make a ship move, but it would always be at sub-light speed because the ship has mass and is moving through space. It could be done by using energy to curve spacetime, but it would take a lot of energy, and the gravity generator would have to be at the very front of the ship. If you want faster than light travel using gravity, you'll have to use an Alcubierre Warp Drive. [Answer] Manipulation of gravity is currently impossible so the plausibility of your question will largely depend on how far outside the realm of plausible physic you think it is. Due to general relativity, it is impossible differentiate gravitation and acceleration on an object from the object's point of view so in theory if you could generate gravitation, you are generating acceleration. Other than that, this is what you are describing if you take out all the physic mumble jumble: [![](https://i.stack.imgur.com/Yt4qV.png)](https://i.stack.imgur.com/Yt4qV.png) instead of magnetic pull, you are talking about gravitational pull [Answer] It's definitely outside of the realm of known physics, but it's not that far beyond how [resonant cavity thrusters](https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster) supposedly might work. RCTs appear to violate conservation of momentum, but might work by pushing against virtual particles to generate thrust. Now, based on our current understanding of physics, that shouldn't work, and it shouldn't be possible to generate usable force from a vacuum, or to break the symmetry of particle formation from a vacuum. If, however, you had a means of causing the vacuum in front of you to generate a temporary imbalance in virtual particles, those particles would have mass, in a similar way that the particles providing the thrust in and RCT gain mass. Those particles would have gravity, and as such would exert a small pull on your ship. Again, that violates the laws of physics as we currently understand them, and probably couldn't happen. Even if that did work, though, the forces involved would be incredibly small. Gravity is a VERY weak force, and generally huge amounts of matter are required to actually create noticeable effects. Either large amounts of matter, or incredibly dense matter, would be required for any significant acceleration. Your best bet would be to cause microscopic black holes to coalesce just in front of your ship, where they'd exert a reasonably strong force for a brief moment before popping back into nothingness. Even so, this type of drive would likely be best for long voyages, where a ship could spend days or months steadily accelerating, rather than for anything requiring quick, precise acceleration. All of that, again, is probably impossible, but it's about as close as you can get to reality for a drive that's generating gravity wells to accelerate your ship in violation of half the laws of physics. [Answer] No external fields or components are required The combination of gravitics and ping-pong balls are all you need. Use gravitics to accelerate your ping-pong balls to the desired speed, then have them bounce off the wall. Each impact will transfer a little momentum to the ship. All you need to add is a ball return to automate reloading of the space drive. It is awfully convenient to have magical physics. I should also point out that physicists evaluating similar drives actually come to the conclusion that such a drive is impossible even with gravitics mostly because of violation of other laws such as conservation of energy, momentum, etc. E.g., as the ball exits the region of alter gravity, it must push against the flow to reenter normal space Sorry about the anthropomorphism. As Barbie says, Gravitics class is tough. [Answer] I like to think of the propulsion issue in terms of space warping rather than gravity. It should be acceptable since warped space and gravity are interchangeable to some extent, but warped space is easier to visualize with lines. If theoretically you can generate two fields on the two ends of the spaceship, one that compresses the space and other that dilates the space, then yes, the propulsion system will work, moving the ship. This is the basic idea behind warp drives in sci-fi. Since you can warp space using gravity, voila ! you have a gravity based propulsion system. ]
[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. My plot is to have temples,castles and cities built on top of the remains of previous structures repeatedly to create a multi-level underground dungeon. My goal is to figure out how many levels this dungeon can have as it ages, and what its height relative to the land around it will be. <https://en.wikipedia.org/wiki/Subsidence> of buildings seems to be a common enough thing. In addition, it seems like the ground underneath structures is depressed in comparison to the level of the surrounding land. At the same time, layers of dust and dirt are continually laid down, and life builds on top of it all. This seems to be called Silting, and it is the process that lays down strata. How would one calculate the rate of silting of large stone structures,ie how long does it take for a structure to be covered in layers of earth, and what calculations are there for the isostatic subsidence of land with large stone structures on them. For example, how long would it take before a city with a 25 square km area, a max height of 65m, and an overall weight of 2 million tonnes, located in a subtropical dry forest, was covered in 1 m of earth [Answer] When it comes to formation of soil, the equation is pretty daunting. About 1 cm [for every 200 years in a tropical environment](http://www.eniscuola.net/en/argomento/soil/soil-formation/how-long-does-it-take-to-form/). Given that you want to cover 65 meter buildings with soil at a height of 1 meter, the amount of time would be the number of centimeters times 200 years. 6600 cm x 200 years= 1,320,000 years That's a lot of time. As to Subsidence, that's going to depend greatly on the ground you build it on, and quite honestly, no one is going to want to build atop a region that unstable. I live in a place where this can happen. Believe me when I say that no one is looking to build on top of the sunken building, because they know it's unstable. It's often a result of limestone, karst topography and a shifting water table. Yes, buildings can unevenly sink sometimes as much as 1 meter a year, but generally they reach a tipping point, where they either stabilize or--half the house falls into the newly formed sink hole. Generally they do not uniformly "sink." That seems to be what you are picturing but it rarely happens this way, and would be strange indeed. There are measurements of places where they have said like "sinking at 2 feet a a year" or something, but you have to realize that is the AVERAGE. There are always places where it's more or less, and it's hell on a building when the left side is 1 foot higher than a the right. I cannot give you an equation for this one because rates of subsidence vary widely, from place to place and soil condition to soil condition. If the buildings are in use, folks may clear things away, or strengthen foundations. It's a better idea to have a sudden disaster hide buildings under rubble that was then used as a foundation. Or-- your city dwellers can deliberately build at a higher grade for plumbing like Seattle! Check out [their underground buildings!](https://en.wikipedia.org/wiki/Seattle_Underground) If a ruler or society decides that they want to rebuild at a certain level, they can preserve the lower levels, sometimes because the original owners complain, sometimes because they want room for sewers, do not underestimate the power of public works systems.Some can just be closed off when building another section and forgotten--there are abandoned subway platforms like this. The issue with natural covering up of dungeons rather than conscious building is that in-fill is more likely to happen. It's not...like a lot of fun for people to dig out an old city, but it is fun for them to explore it. The only way that can happen is if people actually build over it. [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. @AlexP has got it right. Cities rise. From [The Atlantic](https://www.theatlantic.com/magazine/archive/1997/04/underground-rome/376836/) > > By 1580, when Montaigne visited Rome, the classical city was all but > invisible. He observed that when modern Romans dug into the ground, > they frequently struck the capitals of tall columns still standing far > below. "They do not seek any other foundations for their houses than > old ruined buildings or vaults, such as are seen at the bottom of all > the cellars." > > > Here is King Nebuchadnezzar explaining in a dedication plaque why he built the "new" Ishtar Gate. From [ancientorigins.net](http://www.ancient-origins.net/ancient-places-asia/magnificent-ishtar-gate-babylon-001866) > > I, Nebuchadnezzar, King of Babylon, the faithful prince appointed by > the will of Marduk, the highest of princely princes, beloved of Nabu, > of prudent counsel, who has learned to embrace wisdom, who fathomed > their divine being and reveres their majesty, the untiring governor, > who always takes to heart the care of the cult of Esagila and Ezida > and is constantly concerned with the well-being of Babylon and > Borsippa, the wise, the humble, the caretaker of Esagila and Ezida, > the firstborn son of Nabopolassar, the King of Babylon. Both gate > entrances of Imgur-Ellil and Nemetti-Ellil following the filling of > the street from Babylon had become increasingly lower. Therefore, I > pulled down these gates and laid their foundations at the water table > with asphalt and bricks and had them made of bricks with blue stone on > which wonderful bulls and dragons were depicted. > > > This was around 600 BC. Babylon had already been a city long enough for the city to rise to the point that the existing gate had a low clearance of about 8 feet. I read that the rebuild raised the ground level of the area 60 feet. Here is an Egyptian obelisk which was brought to Constantinople in 400 AD. This is a place where people were probably not just piling stuff on top of stuff willynilly and you can still see that the base of the obelisk is at least 4 meters below where the tourists are standing. I found this image at [speacock.net](http://www.speacock.net/gallery/slideshow.php?set_albumName=album264) [![enter image description here](https://i.stack.imgur.com/6SWT2.jpg)](https://i.stack.imgur.com/6SWT2.jpg) So: have your dungeon be the lowest levels. Maybe built by prehuman civilizations! Stuff was built on top again and again but the original strange temples are still down there. Waiting.... This thought - the new upon the old upon the older - leads me to post some text from the beginning of The Rats in the Walls by H.P.Lovecraft. > > Exham Priory had remained untenanted, though later allotted to the > estates of the Norrys family and much studied because of its > peculiarly composite architecture; an architecture involving Gothic > towers resting on a Saxon or Romanesque substructure, whose foundation > in turn was of a still earlier order or blend of orders—Roman, and > even Druidic or native Cymric, if legends speak truly. This foundation > was a very singular thing, being merged on one side with the solid > limestone of the precipice from whose brink the priory overlooked a > desolate valley three miles west of the village of Anchester. > Architects and antiquarians loved to examine this strange relic of > forgotten centuries, but the country folk hated it. They had hated it > hundreds of years before, when my ancestors lived there, and they > hated it now, with the moss and mould of abandonment on it. > > > [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. Do note that the city you mention in your question, 25m2 is a very big city. Smaller will probably go easier. Up and down, Unless you are building things in a bog, where structures sink until they rest on (probably) a sand deposit, cities do build up. With continual habitation my memory tells me it is about 1cm per 100 years. But I can't find a source for that. Alas. --- Up and hurry, But we can make it pile up faster: burn it down, let nature take over for a few (50) years, and resettle. That way you could build up faster. If you have hills people tend to use the caves as well, so you gain even more layers. For a very famous example you can use Troy: [![Troy Layers](https://i.stack.imgur.com/zUUdr.gif)](https://i.stack.imgur.com/zUUdr.gif) While this picture does not show the size of the layers, is does show the ages it was created. Just remember, it took about 2500 years to build it. An other thing to remember is that things do break down, so having whole passages that stay intact is unlikely. [Google Image Search](https://www.google.nl/search?q=troy%20layers&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwinn42R3K3TAhVMYlAKHULMAqMQ_AUICCgB&biw=1813&bih=1107#imgrc=wpEt4KlHtXvyTM:). --- Down and Dig If layers is all you care about, then at the same time dig deeper. Like these [guys in Cappadocia](http://news.nationalgeographic.com/2015/03/150325-underground-city-cappadocia-turkey-archaeology/), central Turkey, who dug out a huge area for refuge. See also [Derinkuyu](https://en.wikipedia.org/wiki/Derinkuyu_underground_city). I think I have found a new holiday destination I want to visit. [![enter image description here](https://i.stack.imgur.com/oVQo3.jpg)](https://i.stack.imgur.com/oVQo3.jpg) [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. As other answers noted, the soil and dirty pile up very slowly. But it could be changed with a bit of fantasy: * Destroy the town by invaders, then build up new then repeat again. As mentioned by [@Flummox](https://worldbuilding.stackexchange.com/a/78443/28789), Troy is an example, [Carthage](https://en.wikipedia.org/wiki/Carthage_(municipality)) is another one. * A vulcanic eruption, wich [could bury the whole city](https://en.wikipedia.org/wiki/Pompeii). Create regular eruptions with 150-200 years of quiet and a strong reason why people would return to the specific location. * Dust storms could help to bury the town. * Exceptional flooding by a river like the Nile could bury cellars only. But almost all of those things will be irrelevant if you need dungeons free for walking (or exploring, fighting etc). [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. In the past, cities often burned down. The rubble was compacted and new buildings were built on top. In many European cities, you can see that churches and cathedrals are at a lower level than the surrounding buildings. And also see [tells](https://en.wikipedia.org/wiki/Tell_(archaeology) "tells") ]
[Question] [ I've recently become interested in the possibility of silicon based life. Assume these creatures developed on a planet with zero carbon (don't question, just accept it), so they have no carbon in their bodies. For this question, it would also be helpful to know what kinds of conditions would be conducive towards silicon based life. (I've excluded carbon because I know it is generally more effective for life-forms to evolve with it.) Now, what would the chemical make-up of these creatures be like? Assume they are nearly like humans, except with silicon. Would they also be made up of lots of water, or would they have ammonia blood? Would they have higher internal body temperatures? Would anything else have to be different? [Answer] Based on silicon's properties, I would guess these characteristics of a silicon-based life form: * silicon compounds resist temperature better than their carbon counterparts so the life form would live in a hot environment or have a high body temperature. * silicon can combine with itself like carbon, but forms weaker links so the life form might not have good structural integrity. It may not grow to a large size or it would live on a small planet with low gravity or thick atmosphere or in a liquid. * silicon oxides are stable compounds so the chemical reactions needed for metabolism might go slow. The creature could have a long life or move slow, like turtles. * silicon oxidizes to the solid silicon dioxide - a life form would have difficulty disposing of a solid so it would not breathe in the same sense as we do. * silicon-based reaction occurs rapidly, so the life form might produce large amounts of energy quickly, but this might also mean that it would have difficulty controlling its own survival mechanisms. [Answer] For nearly any organic molecule you can make a Silicon analogue. The bond is a bit weaker and the properties cann be very different. Take $CO\_2$ and $SiO2$ one is a colorless gas trees like to breath and the other is quartz. So we can't have a critter that breathes in $O\_2$ and out Quartz. or rather you can and probably should. Silicones are the silicon versions of hydrocarbons they don't store energy nearly as well but are used to mimic them in prosthetics. I think that your silica men might be softer and more rubbery than they are usually depicted in Science Fiction where they are usually rock people. The silica Sugar analogue would probably be useless so phosphorous and nitrogen would probably be used to store energy. Maybe this is where the ammonia blood could come in but water would be fine. [Answer] Silicon is a lot less versatile than Carbon. There are no stable double bonds between Silicon atoms, nor ring structures with delocalised electrons. The single silicon to silicon bond is weak compared to the silicon-oxygen bond, hence silicones. There are no long silicon chain silanes. Despite which, it has been suggested that the first sort of proto-life might have been based on aluminosilicate minerals. Clays. They form a huge variety of nanocrystals and have some ability to catalyse and organise carbon organic molecules. Over some hundreds of millions of years the ungrateful carbon molecules learned how to get a life without needing the clays. Just possibly, somewhere else evolution took a different path and clay minerals are there an essential component of all living beings. Note this theory is as speculative as any consideration of the origin of life must be. Only one known example and almost all evidence lost in very deep time. [Answer] Silicon and Carbon have the same bonding order but there are a lot of organic compounds, especially high complexity compounds like amino-acids for which there are no stable Silicon analogues to the Carbon chains. Silicon is too big to form a lot of molecules because it distorts the normal (Carbon based) bond angles between the various components. Silicon-Hydrogen bonds are also weaker than Carbon-Hydrogen so long chain Hydrosilicons undergo more rapid racemization, and because Silicon=Silicon bonds are unstable there are a variety of organic chemical species that it is just plain impossible to form using Silicon instead of Carbon. Silicon based life may exist but it's probably not going to look anything like the Carbon-Water chemistry we're used to seeing. I would expect to see something like either; a highly doped silicate rock that bore more resemblance to a computer chip in it's operation than an organic brain, or a semi-crystal that undergoes some sort of "electron-ripple" chemistry similar to that seen in artificial chlorophyll where a slight instability is propagated through interlocking chemical chains in the form of a single electron being "flicked" from atom to atom leaving the chain structure intact but transferring charge along it. Either structure would allow complex thought processes. I've always favoured the version of silicon-based life that is hot but more-or-less human, they have a type II semi-crystalline brain (just because it's more easily reconfigured thus better for having evolution) that works faster the hotter they get. The rest of the nervous system and the functions thereof would be performed by the same sort of system. They have a body temperature that bottoms out in the mid-1500s Celsius but can be much much higher, they may "breath" when they need to cool off but they don't respire in the sense of taking on chemical inputs from the atmosphere. Their muscles are an electro-responsive Silicon polymer, stable at high temperatures but prone to brittleness below their lowest operating temperature. They build up a layer of "dead" material that acts as skin and thickens as they age giving them an appearance similar to coarse volcanic rock. They eat only to expand or to replace decayed [transuranic elements](https://en.wikipedia.org/wiki/Transuranium_element) that have given up their heat to fuel the silicate thermocouple metabolism, they're not really "alive" as we define it (they fall short of [MRS GREN](http://basicbiology.net/biology-101/mrs-gren/) on a couple of counts) but they'll do. [Answer] To the best of my knowledge, there two broadly plausible possibilities: one operating at very low temperature, the other at very high temperature. The somewhat less plausible route is to use silane (and silene/silyne) compounds, in as-direct-as-possible analog to carbon compounds. Silanes are not as stable as carbon chain molecules, and so would need a colder environment. This means you need a cryogenic solvent, as well- water won't do. Silica, the direct analog for carbon dioxide, dissolves well in various organic solvents (which are used to manufacture, e.g., silica aerogels) with low freezing temperatures, but if there are organic solvents around, you'd be much more likely to end up with cryogenic carbon-nitrogen life instead, or maybe a hybrid that occasionally incorporates silane molecules into a primarily carbon-based chemistry. So, yeah, you need to pretty much eliminate carbon altogether, and that means, most likely, using an ammonia-water mixture as the primary biosolvent. (A mixture of water and ammonia has a lower melting point than either liquid alone.) Like organic solvent, ammonia will react with oxygen, which means you can't have much free oxygen in the atmosphere, so these organisms would need to be hydrogen breathers, or use some other alternative metabolic cycle- perhaps one that doesn't require breathing at all, and relies entirely on simple decomposition of energy-rich molecules. The more plausible option is something based on silicone (-Si-O-) backbones, possibly with organic side-chains. Silicones can make conveniently soft and flexible molecules at human-comfortable temperatures (as evidenced by silicone baking ware), but they withstand high temperatures quite well (again, as evidences by silicone baking ware...) and become more versatile at higher temperatures. In this case, there is a reasonable geophysical scenario that would predispose the development of this sort of life over purely carbon-based: a world with large quantities of sulfuric acid, which decomposes hydrocarbons. So, you have a world somewhere between Io and Venus, which gets much hotter than our world, resulting in a loss of water and hydrogen, and concentration of sulfuric acid. Not as small and cold as Io, and not quite as hot as Venus, because you ideally do want to retain some surface liquid, not just clouds. Conveniently, sulfuric acid also reacts with chloride and fluoride salts, producing hydrochloric and hydrofluoric acids, and hydrfluoric acid will dissolve silica, which would serve to make it bioavailable and provide a means of disposing of metabolic wastes. So, you have a mixture of highly concentrated sulfuric acid with a little water and small quantities of hydrochloric and hydrofluoric acid as the biosolvent, operating somewhere between 50 and 300 degrees Celsius. You don't need to eliminate carbon from the environment--the solvent choice makes the evolution of purely carbon-based life impossible anyway--and you don't want to, because carbon will be useful to incorporate into side-chains and functional groups, just like we incorporate nitrogen into lots of our own "carbon-based" biomolecules. The solvent won't react with oxygen, so there can be plenty of free oxygen (and possibly some chlorine and fluorine) in the air as well, although there may be little motivation for purely oxygenic biosynthesis (whether photosynthesis, chemosynthesis, or what have you); you could instead end up with a mixture of free oxygen and a bunch of sulfur trioxide in the air, either of which could be used as oxidizing agents for animal metabolism. (In our environment, sulfur trioxide is a solid, but it's a gas above 45 degrees Celsius.) [Answer] 1. I think A silicon based life form would... * live in a hot enviroment since silicon compounds are too stable in a not that hot enviroment. (around 1100 degrees, approximately the melting point of silicon sulfite, wich it disposes like we dispose co2) * live inside planets since only there is enough silicon and heat. * consume sulfur instead of oxygen, since there no oxygen available inside planets (oxygen most likely only as oxide). * dispose liquid sulfur dioxide. * have "bones" out of some silicon based crystal, if any. * swim in magma, since burrowing through stone would be a huge energy effort. * get petrified when taken out of magma since most silicon compounds are minerals. * never be noticed by humans even if it lived in earth since they can't isolate magma and keep it hot. (they would noever notice that some rocks are petrified lifeforms) [Answer] I too am interested in the chemistry of Life As We Do Not Know it. Silicon is one of my favorites since I read Hal Clement's Iceworld and later when I saw the "Devil in The Dark" episode of Star Trek with the Horta. There is a lot of skepticism about silicon as a basis for life but here is a relatively recent sci-fi story I published in the net that tries to deal with the objections and even gives a sketch of a hypothetical 'biochemistry' of a higher temperature silicon life form. [Learning Curve](http://www.scifiideas.com/inspiration/featured-stories/featured-story-learning-curve/) ]
[Question] [ Imagine if one day, in the future, random children were born with the ability to cast magic. This magic comes naturally to them, like an instinct, so they need not be taught how to use it, though practicing does make it easier to use. Without refining their skill, the magic these children create are almost purely destructive, such as generating beams of burning light or conjuring up cyclones. Although the magic itself has no side effect, except lethargy when overused, the ability to use magic comes at the cost of knowing more or less everything about the magic, including how to increase your power (by consuming the 'souls' of other magic users). This occasionally leads to the rare psychologically unhinged child/teenage mage who will attempt to consume others to strengthen themselves The odds of a child being born with magic is roughly 5 children per month, worldwide. Not common. Magic can be inherited, though no one (in universe) knows that yet, because all the relevant magic users are still in their late teens (at most - this is a relatively recent phenomena). So, the question is, what would be a realistic reaction by the government (and society) in the face of these magic users? Would they basically go all X-Men crazy on them? [Answer] > > Would they basically go all X-Men crazy on them? > > > Government: YES. People: No (for reasons I shall explain). 1. Lock them up. Secretly. They are people after all. With the rates listed in the question, they're infrequent enough within the population to be too well known about. If the population knew you were abducting kids, they'd be rightly furious. As tragic as it is; teens run away and go missing all the time, many are never heard from again. This gives the government a perfectly plausible cover-story. The only people that will know the truth will be worried mothers, and conspiracy theorists. The public will disregard both as crazy. 2. Study. Determine how much of a threat they are to the country. Laser beams mean that any public figure that goes out in public could be target for an assassination attempt. Cyclones have huge economic impact. Blood samples will be taken, analysed, and compared. If magic ability is in some way genetic, then DNA testing will eventually find it. All it requires is a large enough group of people for patterns to be seen in genes. 3. Weaponisation. Sounds horrible. And it is. But smuggling human weather-machines into a foreign country is easier than smuggling a nuclear bomb. And they're reusable! There's going to be a new Cold War fought because of this. [Answer] The first reaction will be disbelief. And that is entirely understandable, since it is something that has never existed before, and sounds far too fantastic (or lunatic) to be true. After that, especially once it is established to be true, governments will try to seize these children. At least the official version will be that they are a threat to themselves and, most of all, others, but it is to be expected that at least some group will try to weaponize them. Failing that, they will have a regrettable accident. All this, of course, will only happen if any officials ever find out. At the rates you describe, it is fairly likely that the parents would quickly teach their children to keep their powers a secret. It should be feasible, too, since anyone accidentally noticing what happened would first not believe it themselves, and if they did and told anybody no one would believe them. By the way, all this consuming souls business sounds a bit far-fetched to me. At those birth rates, those magic wielders will not get in touch with each other any time soon, and thus have no chance of finding out that "consuming the other one's soul" would be possible, let alone useful. [Answer] The Government angle has already been addressed in the other answers, but one idea that they haven't touched is patronage. While I'm sure governments would love to have these magic user under their auspices, what about powerful individuals/large corporations? This sort of rare potentially dangerous gifted-ness has been fleshed out in cyberpunk novels where hacking has this pseudo-magical role. We live in an era of multinational corporations and exceedingly (scarily) powerful tech companies. Would the governments find out before Google? Now obviously this is setting dependent (much like the comment about Eastern vs. Western cultures). But methods of data flow/aggregation are integral to the question, if your setting is more pre-industrial then cyberpunk is perhaps not as good an analogy as it necessarily includes a large data network. But if its more modern, than the reaction of the people to find the magic users first will matter a lot because it will color the reactions of the masses if there's already a legitimized place in society for these individuals created by their influential patrons. [Answer] For one thing, I think that the government would initially try and recruit these magical children into their own personal army. Having soldiers and spies that shoot lightning is a tremendous asset to them. For the crazy bloke, I reckon that the government would either send out agents with powers themselves, issue out an arrest warrant, assassinate him/her or try and make him/her a member of their army as a necessary evil kind of agent [Answer] Initial Reaction The initial reaction of the government and people will be fear and panic. People have always been scared of what they cant explain using the rules and laws upon which their perception of the world is built. This is a gut instinct which has helped us survive over the years ,.. its evolutionary. So watching someone conjuring up a cyclone the initial reaction will be to treat this person as threat. Later The next step from the government would be to track such individuals and occurrences. What the government does with these individuals once (if) they are apprehended depends totally on humanitarian stand of the government. They may treat this individuals as people who need help or as a threat and act accordingly. Any smart government will not think of weaponising such individuals because that gives too much power to these individuals over the Government itself. [Answer] Sadly, I think most people's first impression would be fear, also because these children would seemingly be unable to control these newfound abilities. No parent would want to allow their child to be put in the same classroom as one that, at least to their understanding, randomly has these devastating attacks which potentially could kill. It would just take one accidental death to merit the encampment of such people, however the government's motives would be shrouded with the excuse that the scope is to study them and better understand them. If scientists are unable to have predictable controlled behavior in these people, they will likely never leave these encampments (though there might be visiting hours or else I doubt if the government could get away with this). The ones that show promise to control will be of most interest to scientists. The government in particular will push scientists towards the extent that these people have to use these powers to say, assassinate a target. This information is invaluable not only to wield that power but also to know how to protect against it in the most certain case that other countries have such children in their possession. Protocols for the secret service would most certainly change. It would no longer be enough to check for weapons. You'd also have to perform background checks on anyone who sees the president (save for political figures, family, and other people who are more trustworthy). Security checks before entering a plane flight would be a nightmare. If a seemingly normal child got aboard a plane and due to uncontrollable attacks managed to puncture a hole in the plane, the plane would most certainly crash. Before you could purchase airplane tickets, you would probably have to go through a mandatory background screening, and this would be relatively expensive. Other than the cost of the ticket, you'd likely have to pay a tax so that a newly founded government agency could perform a background check just so that you could be able to board a plane. The country itself would revert to the witchhunt days and the days of "secret" communists. Children accused of having magical abilities would be quickly picked up and thrown into the encampment despite not having actually shown any particular magical ability. The process would be long and difficult to prove that that child never actually demonstrated magical ability in order to free him or her. In other words, I suspect that everything would become that much more complicated, and this is not even considering the types of things one with magical abilities could perform but only with an uncontrolled "burning ray of light". If enough magic users came together in one place, they will already naturally loathe being there, and this prejudice would only encourage them to begin to think that they are different than everyone else. It would take little for such people to begin considering themselves superior and to start protesting and rioting. It would all create a sort of dystopia and not at all like the kind of world you'd think when you imagine the birth of those who could use magic. ;) [Answer] The Movie "[Jumper](http://www.imdb.com/title/tt0489099/)" comes to mind, where children are born with the ability of teleportation, which practically makes them limitlessly powerful, because they're essentially uncatchable and unstoppable (teleporting into bank vaults to steal money, teleporting around the world to escape capture). They're in constant danger though, because of a radical, religious, secret society that believes it is their God given duty to eradicate all the jumpers. > > "Only God should have this power" > > > They believe the jumpers an abomination, an insult to the power of God, so they hunt down all these children and use special technology to catch them and brutally murder them. it is most likely that naturally powerful children would be considered a threat, and that someone, whether a private or government organization, would try to would seek them all out and destroy them. [Answer] There are already good answers (and even accepted one), but I want to add some information about statistics and genetics that would influence the reactions. First, considering that you have about 5 new magic users per month. For 18 years, that make 1080 magic users in total (0.000015 % of the population). The reaction of the government and/or the people vary greatly with the distribution of those magic users. And it comes down to how they came to have that gene. Genetic inheritance Are those 5 children per month already sharing a genetical origin? Meaning once upon a time there was a wizard or a witch who had plenty of children, and some centuries later, those who inherited the traits start to develop magical properties? This would concentrate the magic users in some culture. Say, e.g., that the witch was Polish. Most of her descendants would be located in Poland and around, probably a substantial part in Russia, Germany and the USA. Maybe a few more in Western Europe. It depends on when the said witch was living, but as an example, that could possibly make 700-900 magic users in the region where she used to live in Poland. 50-100 in both Germany and Russia. 40-140 in the USA. Some 20-30 in the UK, Irland and France, add a few others in Baltic, Slavic and Scandinavians countries and there you are. Of course she could have been travelling. Or be long ago where her genetic pool have travelled more (e.g. Huns, Mongols, Ancient Chinese, etc.). That would spread the occurences, but probably still along the commercial ways of the time. Assuming a concentration in Poland, you have to consider that 6-15 are already dead: stillborn, death in infancy, etc. Which in that case would be negligible. In that example, the government of Poland would probably learn about the strange situation and by discussions with EU, and NATO, most of the Western World countries would know about it. The high concentration, coupled with the occurence of cases elsewhere would directly point out to the genetic origin of the effect, and they could predict (to some extend) the likelihood of the new-born children. A few missing out in bastard lines. It would be pretty hard to abduct the children without being noticed, because of the high concentration. Furthermore it would be hard to bloc that information to spread that in some region a lot of children are strange. Nevertheless, I expect, the governments would try to impose a martial limit on the inhabitants. Probably closing the whole region off. The few cases that could be seen outside would probably be sent to study institutes. Genetic mutation Now instead, we could suppose that Magic (itself), or some other way creates mutations in the genes of babies-to-born. This could be equally distributed. If that were the case, all countries would be affected, proportionally to its inhabitants. That would make a different count: about 150 born in India, 200 in China, 150 in Africa, 75 in Europe, 40 in the USA, etc. Considering the infant mortality rate of some of those countries, it is likely that already 100-200 are dead by now. Ignoring the children under 3 years old, which might be slightly unnoticed, we are down to, say 800 children in total. Most of them being in India, China, South-East Asia and Africa (around 510). It is likely, in such a case that some regions would consider the children devil and basically lynch them. Countries like China, having sufficiently large amount of users, would embrigade them into some "schools" to see the military/economic potential, without caring about the parents too much. The USA and Europe might just set plans to identify and abduct them. The rate being low enough to get unnoticed in those countries. Secrecy from the main public might be kept to some extend. Now would the genetic factor be identified? It is not so likely. Indeed in countries with stronger states, the children could be found from a relatively early age and kept separated/isolated for studies. In other countries, you might see some teen pregnancies, but there, the tracking is fuzzier. Conclusion The mode of acquisition of the "magic gene" greatly influence the reaction, the spread of information and the number of users. [Answer] With the family being witness of the strangeness of the children, there is probably some fear that would ensue. Both from the direct family and from the people very close to them. If the child is loved before the magic start emerging, the family (and close friends) will probably try to protect him/her. The first reaction would be for everyone to tell them NOT to use magic. Wiser relative and adults might try to teach them techniques to "control" the strange things they do if those things aren't too strong. If things get out of hand, but the child is otherwise loved and compliant, the family will probably try to hide him/her. Maybe send him/her to a far away place where there is relative who could take care of them: "You will be living on the farm with Grampa for now" Of course this only work when the child was not a problem before magic started and with the assumption that some open minded people find more important to help the child then to get rid of him. Family who are more afraid, who find that unnatural or "demonic" might refer the child to the church or even to the health care system. [Answer] The best investigation of this I've seen was by Timothy Zahn in the book [A Coming of Age](http://rads.stackoverflow.com/amzn/click/B0094ANUOK) In it he posits a society that was thrown into turmoil when children developed telekinetic ability (which they then lost at puberty). Societal stability eventually achieved by indoctrinating older children to supervise their younger peers. ]
[Question] [ In [this question](https://worldbuilding.stackexchange.com/questions/17919/what-would-happen-to-an-urban-fantasy-earth-hit-with-a-supernatural-planet-size), I asked what would happen if a supernatural EMP hit an urban-fantasy Earth. The answers pointed out a flaw in my assumption: an EMP, supernatural or otherwise, would not likely have the effects I need. Oops! Therefore, assuming a modern urban fantasy setting (thus, the world is "ours" in the present time, with the known continents, cities, technology, and general environment), *what kind of singular event could do all the following, without also wiping out life as we know it?* a) Disable or destroy all manmade satellites (and thus a lot of communication); b) Take down the power grid for weeks; c) Render communication via cell phones and computers virtually impossible for the forseeable future; d) Other effects optional! Assuming my bad guy successfully triggers this event, whatever it is, what would be the effect on the following systems in particular? a) How would cars - from old, non-computerized models up to the Tesla - react? Would they be disabled, and if so, for how long? b) How would hospitals react? Would an event capable of knocking out power on this scale temporarily or permanently disable their backup generators, or would they be able to switch over with little to no disruption? c) Are there any other major side effects, either on manmade structures or on the environment? The event can be a one-off phenomenon, such as a solar flare or EMP detonation; or it can be some kind of ongoing thing (like fluctuating magnetic fields or something). The main goal is to achieve those three primary effects all via a single mechanism. (If the answer is, "no known real-life event can do all those", that's fine too! The bad guy has Magic(tm) so I can fudge a little; I'm just hoping to ground the magic effects in as much science as possible for realism's sake.) [Answer] # [Coronal Mass Ejection](http://en.wikipedia.org/wiki/Coronal_mass_ejection#Impact_on_Earth) It will knock down communications as well as potentially knock down satellites and power grids. A CME would not prevent diesel, coal, or wind turbines from generating power; the issue would be the blown transformers. The CME could literally change the orbit of satellites as well as ionize them, potentially making them unable to adjust their courses. Enough charged particles hitting radio antennae could potentially fry their circuits as well. # Weaponized EMPs This can cause [some havoc](http://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse#Effects), but not really knock down satellites. It is speculated that an EMP would disrupt electronics, essentially frying circuits or wiping all electronic memory. It is easily countered, however, because a [Faraday Cage](http://en.wikipedia.org/wiki/Faraday_cage) would protect all electronics from any damage. EMPs are not "as destructive" as a coronal mass ejection because they cannot cover the same area. # The Reactions * Cars: cars don't care if they don't have electronics. Most modern cars do have electronics, however, and many rely on them for their increased performance. Knocking out the computers on a modern car would render it useless, especially if it does not rely on mechanical structures, like clutches. In any case, the general rule here would be that older cars would be more likely to function, as they have less electronics in them. * Hospitals: I foresee hospitals doing just fine, at first. They [have backup generators](http://www.dieselserviceandsupply.com/generators_healthcare.aspx), but it's unclear how long those generators would last; my source says a hospital can stay working for 8-24 hours. If a hospital has an abnormally good supply of diesel, the generator could work longer. After that initial time period, panic would set in. People would likely die, because a hospital without power cannot do surgery or use fancy things x-rays, CAT scans, and so on. [Answer] The other answers have been pretty scientific. I'd suggest something more magical. Mass transmutation The bad guy casts a spell that continuously transmutes all monocrystalline silicon into gold. Useless, worthless gold. Boom, goodbye transistors. Goodbye microchips. a) Disable or destroy all manmade satellites (and thus a lot of communication); All existing satellites use microchips, so yep, they'd be disabled. b) Take down the power grid for weeks; While the raw generators would work, the control circuitry will be inoperative, leading to either clean shutdowns or the things ripping themselves into pieces. Eventually vacuum tube based systems would be built and designed, but indeed, there wouldn't be any power. Not even photovoltaic solar power. Some sufficiently low-tech power generators might work. c) Render communication via cell phones and computers virtually impossible for the forseeable future; Definitely no computers. Eventually you'd get the re-emergence of old fashioned WWII era radios. But yes, we're basically resetting to WWII. No bad biological effects, because crystaline silicon is not found in nature. [Answer] The very simple way is just to bomb all The world's power plants. Admittedly this is rather difficult since they have high security measures preventing people breaking in and bombing them. The next way, which has already been said, is to figure out the computer systems. Most power plants are computer controlled so if you hack the system you can shut it down. EMP is a viable method but you need a very big EMP to cover the entire planet, or you need some form of outside influence to create the EMP. Coronal mass ejections can do this, or gamma-ray burst from a quasar or black hole. If you get hit by GRB from a black hole though you're probably too close to it. [Answer] A mass takedown of the world's computers would achieve these goals. A clever hacker might be able to do quite a bit of damage, but there are still a lot of systems that aren't connected to anything else and thus difficult to hack. A more plausible way would be through a remotely-triggerable hardware backdoor. For instance, your bad guy may have been planning this for a while, and over the years has secretly bribed, blackmailed, and extorted the world's major chip fabrication companies to secretly add extra circuitry to the chips that they produce. The bad guy could activate this extra circuitry by broadcasting a specific signal (for example), and the circuitry would effectively cause permanent, fatal damage to the chip. This would allow him to destroy the vast majority of the world's electronic infrastructure at will. Continuously broadcasting the signal would effectively make all spare parts worthless, as they would self-destruct as soon as they were powered on. Assuming that you want something that a single bad guy can trigger at will, this seems like the option that would involve the least amount of "magic" ([such things](http://www.techrepublic.com/blog/it-security/researchers-create-nearly-undetectable-hardware-backdoor) are [already possible](http://securityaffairs.co/wordpress/17875/hacking/undetectable-hardware-trojan-reality.html) today). The only thing that you might need to fudge on is the specifics of the activation mechanism. With something like this, any vehicle with a computerized engine wouldn't work at all. Older, purely mechanical cars should continue to run normally, provided they can find a non-computerized gas pump. Since this is strictly focused on electronic devices, it should have no direct effect on the environment or on non-electronic things like buildings, books, or roads. There will undoubtedly be indirect effects caused by the sudden lack of computer control, such as a dam no longer being able to regulate water levels and causing floods downstream, or an entire generation of the population finding themselves unable to coherently communicate with others without autocorrect and spell checkers. [Answer] 1. Coronal Mass Ejection could maybe provide the answer if the evil mage possesses the power to seriously mess with the sun to provoke repeating ejections. Otherwise it would just hit once, so computer chips would be disabled (see bottom of answer) for a few minutes to hours, or in the case of satellites maybe longer. Plus it's a phenomena which isn't really understood yet, so you risk being outdated by newer findings. 2. One EMP would rather kill everyone than disable communications, but it's still mentioned in several answers here. By adding enough magic you could have lots of small EMP bursts inside each system you want to destroy. If you have some analytical magic to find all semiconductors and then change the electromagnetic field inside those semiconductors drastically (preferably several times back and forth for alternating current) then you would induce current which could melt any electronics and which wouldn't do much to natural occurrences of semiconductors (wouldn't conduct enough, while there are always low resistance paths in computer chips). But that wouldn't be a single event, that would be billions of events, for each occurrence of semi-conductive material. Would result in destruction of computer chips, see bottom of answer. 3. The mage could just switch on and off the magnetic field of Earth, without directly affecting electrical ones. Initially I thought this was a good idea, but now I think it would be similar to EMP. By just switching Earth's field you would just achieve a temporary effect (disabling chips) and by doing it with a stronger field you would also kill everything by starting to ionize practically everything. But you could have the mage keep switching the field on and off for as long as you like to disable computer chips. Would also kill some birds relying on the magnetic field to navigate, probably. You could also do it with a switching electromagnetic field instead of just magnetic (wouldn't help the birds). 4. Not a single event: Computer viruses could disable computer chips in theory (in some cases destroy, for satellites which can change their course and maybe some industrial systems). Enough of them are networked to make this effective given some preparation time for the virus to spread. Needs lots of analytical power (math and computer science). If the mage could summon some ultra intelligent being, or a life-form which lives in electromagnetic fields or something... ## Consequences of disabling or destroying computer chips: disabling: Only a few chips would break completely, most could be restarted once the phenomena disabling the chips stops breaking: The phenomena destroys all chips, so the parts about rebuilding them applies * wouldn't kill anyone directly * would destroy modern cars but some percentage of older ones would survive * would destroy the stuff controlling the power grid, taking it down without destroying the generators and other infrastructure * would destroy lots of vital systems in hospitals (not the power, there would be lighting over the emergency generators unless it was LEDs, but /lots/ of stuff wouldn't work, they would essentially be thrown back like 50 years in their capability) * would leave stuff like generators, power lines or (non-LED) light bulbs themselves intact * wouldn't be a complete apocalypse, infrastructure would be undamaged, within a few months to a year production of new computer chips could probably start and society could rebuild. [Answer] Another option that presented itself to me is if an Artificial Intelligence goes rogue. Computers are used in just about everything, so any modern power stations are suddenly fed the wrong instructions and cause massive destruction. It wouldn't work on some older power stations, and Germany would suddenly be doing fantastic with its solar power, but most first world countries would be pretty bad off. [Answer] In the book Starbound, by Joe Haldeman (one of the most influent scifi writers ever), the Earth is at odds with a much more powerful civilization. The other civilization has reached technological singularity, which means that by Clarke's third law, all their technology seems like pure magic to us. At some point, the aliens get relly mad at humanity. At some point, they turn off the electricity. No devices that require electricity work. Not even wrist watches. They let biochemical processes that use or produce electricity work, though, so people don't drop dead because their brains stop working. A few seconds prior to pulling the plug, the aliens broadcast this message to humans, which I think is the most awesome way to turn the grid off in a fictional world: > > All this energy that you call 'free' comes to you at the expense of a donor world in a nearby universe. You are donors now. > > > So, you could have it like this: due to some quantum law that we don't know about with our current understanding of physics, all the electricity we use comes from another world. This is not far-fetched: Nikola Tesla believed that all forms of energy ultimately came from the Aether (a concept later dropped by modern scientists). Your bad guy can then reverse the process, making your fantasy world provide the power to some other plane of existence instead of drawing power from it. ]
[Question] [ I am working on building a somewhat-near-future(500 years, but after near-total-annihilation and then induction into a more advanced galactic society) in which infantry-based wars are fought throughout the galaxy, mainly by humans. Due to the inherent danger of fighting in a world where FTL ships and nuclear fusion reactors exist in large quantities, wars will be strictly regulated by a super-advanced autonomous group. This group ensures that opposing armies are relatively equal in power, and with the kind of technology that will lead to an interesting fight. The best army, then, is not the one with the most money, soldiers, or technology, but the one that's able to accurately predict what tools work best in the context of the location of the battle and the equipment being used by the enemy. Thus, I want to know what pros and cons laser and projectile weaponry bring to the table. The kinds of things I'm mostly interested in is what planetary conditions or tactical situations each would excel or be hindered, and what kinds of armor or fortifications soldiers would use to protect themselves from such weapons. Perhaps also the expected size, shape, maintenance of the weapons. Basically, why would you use one over the other, and why you would later use the other over the one. By 'projectile weapons', I mean the somewhat-distant-future of modern guns, with some sort of explosion in the barrel delivering force to a small bit of metal that then flies out of the barrel and into the enemy. By 'laser weapons', I mean something that fires a beam of energy with the capability of causing fatal harm to someone. I'm hoping for an explanation of modern laser technology, but with the size, weight, and usefulness of a modern rifle. This is something I don't have much knowledge on, so an explanation of exactly what would happen to a laser-shot victim and in what timeframe would also be appreciated. Bonus points for a scientific explanation of plasma weaponry, if that's different than laser weaponry. [Answer] Laser Weapons Pros: 1. Flexibility. Presumably you can make a laser that's extremely adjustable on it's intensity, meaning you can literally dial your weapon for exactly what it is you're facing - no point in using the anti-tank laser vs puny humanoids. You could double it as a strobe-type light attack weapon to blind your enemies, or focus for sustained output as a cutting tool. 2. Stealth - it's likely that there's no way to say that a specific Laser created a specific wound - there's nothing like the current pattern-matching police can use to match bullets, there's less physical evidence. This can be important in warfare too because you can hit someone and they have fewer ways to figure out where the attack came from (assuming you use non-visible light and things like that). And lasers are quieter. 3. Accuracy - it's likely that with computer-aided support lasers are much more accurate than projectiles at short to medium ranges in ideal conditions, since you can ignore things like gravity (keep in mind that ideal conditions though, add in a storm and projectiles pull back ahead). Cons: 1. Countermeasures. There are a lot of additional countermeasures you can take against lasers that don't do anything against bullets. Mirrored armor (include non-visual light here), or armor that adjusts it's color to precisely match laser frequencies for maximum deflection. Both of those degrade the amount of power a laser weapon can deliver. Lasers are vulnerable to anything that impacts light, which includes atmospheric effects or water vapor - defending forces could create a screen of steam which would defract any lasers that fired through it. And it would be very iffy to use lasers in the rain at any significant distance. Or think about scattering light-weight mirrored chaff to deflect part of a laser beam and reduce the power it can hit you with. 2. Line-of-sight. For close in combat this is important for things like tossing a grenade around a corner, but it's also significant for medium or long range combat too - indirect artillery fire is something you need projectiles for, or shooting around moons/planets. 3. Time-on-target. You have to hold a laser on an exact spot for it to have effect. This will be extremely difficult against fast-moving targets. Realistic lasers aren't lightsabers, you can't just wave them through people - doing so likely won't even significantly impact decent armor. Projectile Weapons Pros: 1. Countermeasures - It's harder to stop bullets. I mean sure you can add armor, but a big enough gun and those things just become another part of the losing end of the mass \* velocity equation. It's up to you where your tech ends up, but traditionally there's really no defense against a big enough gun - it will plow through anything you put up against it, and at a high enough speed that dodging isn't a realistic option. And armor works against lasers too. 2. Specialty rounds - exploding, self-guided, penetrating, non-lethal... possible to do a lot with rounds and switch between them. The downside (why lasers are better at this) is with a gun you only have the ammo you have with you, and taking more of Ammo B subtracts from Ammo A. With a laser it's all the same power source. Cons: 1. Logistics - I suspect carting around bullets is harder than a power supply and/or batteries, but I could be wrong. Theoretically a self-powered laser could work for weeks at some sort of output, but a gun can always run out of bullets. 2. Guns are loud. Break the speed of sound and you're making a ton of noise, really no way around this (unless you want to have stealth rounds that "magically" smooth the air to prevent that... but I think that's stretching). There's really no way to hide that you're using them, and sufficiently advanced technology should be able to track bullets back to their originating point. [Answer] For projectile weapons, modern-style explosion shoots a bullet guns probably won't have much on an advanced laser system. However, there are other projectile weapons that are much more likely to stay relevant. Grenade launchers, rocket launchers, and rail guns, for example, all have some significant advantages over lasers, as well as some weaknesses. Projectile Weapons Projectile weapons essentially break down into two categories: weapons that shoot something that does something (in the case of a grenade that 'something' they do is exploding), and weapons that shoot something really fast. The first category of weapons has a whole range of capabilities that lasers don't have. It's possible to shoot a rocket around a corner or a mortar over a building, and a grenade can be launched through a window. Most of these projectiles then explode, so precise aiming isn't required. They call also be packed with chemical agents, smoke or incendiaries, giving them lots of tactical uses. The second category of projectile weapons, ones that shoot things really fast, works a bit differently. A rail gun effectively fires something in a line, unless you're shooting it over distances of tens or hundreds of miles, so it can't go around an obstacle. What it can do it place a huge amount of energy in a very small area, leading to lots of destruction. A rifle-sized rail gun is likely going to need to charge capacitors, and will make lots of sound and light, since the projectile will be moving fast enough to turn the air to a glowing plasma behind it. It's also likely to make an explosion when it hits. Basically, the rail gun will be the future version of the bazooka. Laser Weapons Laser weapons are a bit different. They're quiet, tunable, and hit their targets instantly. The navy is looking at using laser weaponry as a deterrent against asymmetric threats, such as small, fast boats and UAVs. It's harder to get the power in a laser required to blow through the side of a building, but they're much more effective against small, fast moving targets. They also suffer far less damage and degredation than projectile systems, so they can be used to pick off [swarms of weaker enemies.](http://www.onr.navy.mil/Media-Center/Fact-Sheets/Free-Electron-Laser.aspx) So what's the difference? Essentially, the laser will take the place of modern sniper rifles and assault rifles. It's not as great of a weapon against an armored target, but it shoots fast, far, and accurately. Explosive launchers will continue to do what they do today, with the exception of taking out hardened targets. Nothing else can attack someone on the other side of a building or launch nerve gas. Rail guns will be the go-to weapon for hardened targets. They do lots of damage to a singe thing, and are difficult to defend against. Both rail guns and lasers will require huge amounts of power, though. This is the biggest change in technology that will be needed to get them to a point where they can replace modern weaponry. If power is limited to what could be stored in a next generation supercapacitor, a laser or rail gun may be limited to only a few shots, making them good weapons for sniping or attacking an armored target, but suboptimal at close ranges when compared to modern conventional weapons. [Answer] It hasn't been properly addressed, but the biggest constraint of a laser weapon is the power source. The power source in traditional, explosion based weapons is a chemical reaction and the expansion of gases from that reaction - this is used directly. With laser weapons, we need a power source that has larger power density than the above explosion method (due to power loss on converting to optical and power loss over distance), but I am assuming we need that power source not to explode on first use as it would kill the operator, not the target. On the other hand, if we're OK with it exploding, we just have a a grenade that can be tossed. Basically as such power density, an energy release would be so powerful that no metal or alloy or composite can physically hold it together, so we're talking some sort of magnetic or optical or gravitational method to hold the power source in place. Pretty much like any fusion reactor holding plasma in place with supercooled, superconducting magnets. And since such tech must be available for lasers to work in the first place, this unlocks a whole class of weapons where projectiles are propelled by the same tech that holds the power source together. In other words: railguns, which are my favourite sci-fi weapons. They can propel anything from tiny metal particles, to create a deadly cloud of 'metal storm' all the way to launching whole big rockets and even whole ships, where the 'rail' can stretch half the planet... [Answer] Adding to the existing answers and as it has not been brought up so far: Frank Herbert's Dune offers a "technological scenario" with quite a major drawback of laser weapons. A shield (so called Holtzmann Effect) is invented that blocks physical attacks (or to be more precisely to prevent penetration by fast objects like bullets, mortar rounds, you name it). Furthermore a violent reaction of said shield with laser weapons is postulated - killing both the attacker and the attacked. So the tactical situation being: Bring your lasgun to a fight with shields and die horribly. There is of course another catch to the idea - as a single suicide attacker with a lasgun could wipe out entire battalions of the enemy it is stipulated that the resulting explosion would be similar to an atomic explosion with rules of conduct (the Great Convention) banning the use of atomics. [Answer] I don't want to repeat things that others mentioned. Here are two new points which you could just mentally add to the winning answer: Lasers are quite inefficient today. Roughly half the energy is lost in the machine, the other half is transported to the target. This means that they overheat faster and need more kg of ammo or fuel than a comparably strong projectile weapon. There are chemical lasers which use the burning of some material as power source. Those will generate more vapor than comparable projectile weapons, and today the vapors are also toxic but of course you can change that in your book. Second point is about projectile weapons in a singularity tech context. Today most projectile weapons are slugs of metal, as heavy as you can get them, which are passive once they are on the way. The maximum you do is having an explosive or splintering head. But already today, the big artillery grenades can extend little wings and correct their course with an internal GPS during their 30km or 40km flight. That's today. One sensor (gps), basic steering, done. Just minify this and amplify the tech capability in sci-fi context. They can have more and better sensors, intelligence, control over their flight path. Rifle rounds may correct for inaccurate shooting and wind/coriolis deviation. They may choose the weakest point of the target to fly in. If you shoot a salvo of three or four, they may communicate and choose a different target soldier each, if the targets are near each other. They may have a hollow shape charge head they trigger once they are close enough, 50cm before they impact. They may communicate with your rifle so that it shoots one, two or three rounds on a single pull of the trigger, just as it estimates tactically best fitting. And so on. In short, forget bullets and rifles of today. Rather think of them as active participants of the battle, with a certain degree of intelligence and some sensory on board. With this, I guess the balance leans quite to the bullet side. Back to the lasers. If the lasers are directed by an electronic without moving parts, (which is being developed today for LIDAR) they might be fast enough to blind the bullet sensors, and if their resolution is high enough they might transfer the impression of targets to the sensors where there are none. Holography is done with lasers - so if you could project an image into the sensor of an approaching bullet, you can derail it. So the role of lasers could be an active and intelligent defense, without which the squad would die in a tenth of a second. [Answer] lasers are good for attacking people with no armor since its quiet and it has faster fire rate and more ammo while while bullets are better for armored things like tanks since bullets can break metal while lasers take more time to melt it and it also heats up short, laser: good for attacking people like. bullets: good for attacking armored things and people but needs more ammo [Answer] The big cons of projectile weapons are 1) they reached their peak about 100 years ago. 2) the ability to mass produce graphene would render them obsolete. EDIT Laser weapons offer the following benefits 1) Range in space: Lasers travel at the speed of light, allowing 2) Power: as far as I can tell there's theoretically no limit on how much power can be added to a laser, barring finding a source for it. 3) Logistics: any good source of electricity could be used to charge a laser's batteries. Projectiles have the following benefits 1) Indirect Fire: being affected by gravity means that projectiles can be launched over an obstacle and hit something behind them. This potentially offers increased range from the ground. 2) Versatility: a laser is just a laser, but projectiles could produce smoke, fire, gas, or any number of other effects. 3) Reliability: laser's may end up being finicky weapons that are prone to breaking a lot, or at least they're frequently depicted. There's one other issue that's much harder to take a side on: Atmospheric Interference, which could cause the laser to become to diffuse to be effective, or it could cause too much drag for the projectiles to be effective. ]
[Question] [ Exactly what it says on the tin: how would one go about making a subdermal (i.e. under the skin) [Faraday cage](https://en.wikipedia.org/wiki/Faraday_cage)? Specifically, are there any physical or biological principles that could be applied to do such a thing, while doing so in a fashion that is consistent with known biology and physics? Preferably, this could be something that an infant could be genetically modified with and that they could "grow into", but I'm willing to take all comers. Inspiration [here](https://worldbuilding.stackexchange.com/a/216544/87100). [Answer] # Frame shift: subepithelial (superdermal) Faraday cage This is an answer to a slightly different question: Putting the conductive layer under the dermis is hard, because the bottom edge of the dermis is irregular and intertwined with the hypodermis. It could be placed more deeply (superficial fascia, etc), but I'd rather look to the boundary of the two major layers of the skin: the basement membrane. Putting the cage above the dermal layer means that it defeats miniature spying devices with which the victim might have been tattooed via weapons shot at protests (I've seen a paper proposing these about 20 years ago, ought to look for it...) or injected/vaccinated etc., which could hide in the dermis itself. The basement membrane provides a fairly continuous barrier around the body. We just need to make it electric. For this I'll suggest [beta-carotene](https://en.wikipedia.org/wiki/%CE%92-Carotene) as raw material. This is pretty much what biology uses for wire - in plants, it collects light for photosynthesis, and in humans, related compounds (vitamin A and more specifically 11-cis-retinal) are used to detect light. If we eat it in large excess, the skin will take on an orange color. We're going to change that color so it absorbs a wider range of (lower) frequencies. [![beta carotene with 11 conjugated double bonds](https://i.stack.imgur.com/IodFF.png)](https://i.stack.imgur.com/IodFF.png) The trick of this molecule is in the double bonds (=) which can be shifted to either side and still connect all the atoms correctly, if charge is introduced to one end and the other end. All we need to do to make it more graphite-like (conductive) is to extend this network by an enzymatic reaction that links these structures together with another bond. We need to evolve a new enzyme from scratch, most likely, which is a task of some difficulty but definitely doable, especially since there are many known domains that bind to and react with vitamin A derivatives. I only took the briefest look at PubMed to scan for something already in existence, and there's a chance if you dig into KEGG or other compilations of biochemical pathways you can find something useful already from nature. When making such an enzyme, we should tweak it during development so that: * It has a relatively poor binding affinity to beta-carotene. We don't want it stealing retinoic acid needed during development or vitamin A the baby needs for night vision - only when beta-carotene is consumed in excess will an appreciable amount bind and react. * The reaction has some reversibility. We're not going to spend a fortune in energy to make this happen, and we don't mind if the network can spontaneously be broken down when beta-carotene concentrations are low. This will cause the network to double as a vitamin storage for the infant and ensure it is possible to give up the cage with a prolonged period of sticking to the Recommended Daily Allowance, if there is a medical imaging issue. But vitamins with megadoses of beta carotene have been very easily available; and if that fails, there are carrots (yikes!), so this is not a large bother. * The enzymes for the reaction need to include binding sites that attach somewhere on proteins of the basement membrane, for obvious reasons. Otherwise we're laying these down in random places. They should be secreted by basal epithelial cells, I suppose. Their production should be very strongly repressed in any tissue of the eye, and their activity should be allosterically inhibited by ceramide or other compounds common in the retina. More safety considerations would be needed ... we don't want any foul ups! [Apology for a minor jest: the proper term is supradermal, but "Superdermis" sounded more heroic] [Answer] Tattoos made with conductive ink have been proposed. All the examples I've seen so far have been surface ink. I'm not sure if that's for reasons of toxicity or because people don't seriously want to have permanent circuitboards inscribed in the skin. But the surface ones are conductive enough to attach lights and power sources. See [Silver Nanowire Inks for Direct-Write Electronic Tattoo Applications](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689233/) [Answer] It would be difficult to get a biological process that'd create a metalic mesh, becuase the thing DNA is good at making, protein, and similar biology-ish chemicals is the thing metal isn't. However, all is not lost! It doesn't necessarily have to be metal! There are conductive proteins, and it might be feasible that a correctly designed mesh would have similar properties to a faraday cage. Heres at least one suggestion;- <https://pubmed.ncbi.nlm.nih.gov/27409066/> I'm not too sure the physics of this, and I'm not sure an internal faraday cage is going to be particularly useful, since the goal is to keep that EM energy away from the body, rather than ground it inside of the body. That might require a physicist to chime in on this. I might add, that grounding is important, the EM captured and diverted by the cage has to go somewhere. Newton does not negotiate with terrorists and sci-fi authors, conservation laws are a constant in any concievable universe worth concocting.. So you'd have to work that problem out too. If you put it on the surface though, you could have your character displaying a nice metalic sheen, since one property of conductivity is reflectivity. [Answer] Blood vessels are a wonderful criss-crossing madness on their own. I'm not entirely certain how feasible or survivable this is, but since there is iron in our blood and copper in the blood of molluscs I'd imagine it wouldn't be too big of a stretch, even if nothing in nature currently has this, for the body to use iron/copper atoms in the construction of a person's veins at a relatively high amount/concentration. This may lead to something like the veins themselves being slightly metallic with all the good and the bad that comes from that. Who/whatever has these veins would be rather conductive throughout their whole body and will have a bit of a bad time at airports and all sorts of situations that involve metal detectors. [Answer] Bad news: to protect against high voltages, you need a very low resistance, probably only to be found in metals. So unless you go the way of some semi-plausible body-temperature organic superconductor, which you could, the only alternative is a metallic mesh, probably gold, or copper or silver sheathed with something biocompatible and non reactive. The advantage with gold is that beside having very low resistance, you can have really tiny wires, that do not interfere with the organism and need little sheathing. To thread the wires throughout the skin, you'll need either specialized mites (genetically engineered Demodex for example, except they'd need to burrow - so, something more like [D. Medinensis](https://en.wikipedia.org/wiki/Dracunculus_medinensis)) or nanomachines, and a gold-based skin lotion to supply them with the raw materials. The lotion could contain millions of really tiny carabiners, and the mites would assemble them in chains and thread them throughout the organism. Or the mites could assemble the carabiners themselves out of ordinary materials, building exotic compounds such as bond-strained thiafulvalene-catenane ([fulvalene](https://hal.archives-ouvertes.fr/jpa-00231730/document) was one of the first groups used in high temperature superconduction back in the '80s, and catenanes are a novel class of pseudopolymers that possess literally infinite flexibility. Best of all, they could be built from ordinary organic CHNOPS if one had the appropriate molecular machinery. The only hand-waving here is the hypothesis that bond-straining certain groups could "gift" them with superconductivity, as it seems to happen with [thiocarbo-pseudohydride](https://en.wikipedia.org/wiki/Carbonaceous_sulfur_hydride)). [Answer] If your idea is protect the whole body from microwaves you are out of luck. No way to metallize a human body skin is scientifically plausible. But human body skin and muscles are rich in salt and salt is conductive. Maybe if you connect such tissues to earth you cold make a reasonable Faraday Cage. But attention!!! It can work to block low energy electromagnetic waves. It will not protect from strong microwave action. As Adrian Colomitchi has commented it is not a good idea, and, connect skin and muscles to earth cam make you much more in risk of ordinary electric shock. But if your idea is people were born with a natural "Tin foil hat" you could be more lucky. You need to metallize only the skull. I think, maybe, because human skull is mostly made of mineral (calcium) matter some none could mess up with DNA to make the human skull bone metallized with iron, maybe cooper. ]
[Question] [ Essentially, my question is, can one larger black hole be split into a system of smaller black holes? I'm assuming energy requirements will be prohibitive, and that it may not be possible without exotic matter with negative mass. Can, if energy requirements are not a problem, and exotic matter is available, a black hole be split into multiple smaller black holes? [Answer] No, black holes are scientifically inseparable. No amount of energy can split them apart. Black holes can "evaporate" with time, but this process is more akin to death rather than birth. If this deity can directly manipulate the fabric of spacetime, then splitting would become feasible. But if you want to explain it, you would have to create your own physics. [Answer] [Alexander's answer](https://worldbuilding.stackexchange.com/a/142367/627) is completely correct; there is no way to split one black hole into smaller ones. I think, though, that it might be worth explaining why this is the case, particularly because there are two independent lines of reasoning that come to the same conclusion. If you want to split a black hole in your universe, it turns out that you'd have to throw out both thermodynamics and geometry. ## The thermodynamic argument Black holes have entropy, which is related quite neatly to their areas: $$S=\frac{k\_BA}{4\mathcal{l}\_p^2}$$ where $k\_B$ is Boltzmann's constant and $\mathcal{l}\_p$ is the Planck length. Now, the second law of thermodynamics tells us that the entropy of an isolated system cannot decrease, and it turns out that [we can generate inequalities](https://physics.stackexchange.com/a/288856/56299) telling us that if a black hole were to split into two smaller black holes and keep all the right quantities conserved (e.g. mass, charge, angular momentum), the entropy of the system would decrease. Therefore, such an event would violate the second law of thermodynamics, and therefore it is impossible. ## The geometric/relativistic argument There's actually a completely independent argument [attributed to Hawking](https://projecteuclid.org/euclid.cmp/1103857884) based purely on geometry, relativity and causality. The finer points of it are beyond me, but it boils down to the idea that splitting a black hole would cause two [null geodesics](https://physics.stackexchange.com/a/188865/56299) to begin at the final point of contact between the two black holes, which turns out to be impossible. --- We then have two independent arguments for why you can't split a black hole. Any worldbuilder interested in getting around them has to get rid of both thermodynamics and geometry (and, by extension, relativity) and still manage to create a self-consistent universe in which black holes can even exist. Ignoring one or more conservation laws might solve the thermodynamic objection, but then we're just being silly - and only addressing half of the problem. [Answer] While you can't split a black hole in a conventional sense I wouldn't completely rule this out because of Hawking radiation. The smaller the hole the hotter it radiates--but that's because more of the virtual particles are escaping. What happens when you construct a handwavium machine that pulls all those virtual particles away from the black hole? It seems to me that you could turn the evaporation rate up as high as you have the energy to power it. Pulling these particles away will of course be incredibly energy intensive--but what if the machine is powered by dropping them down another black hole? I would not want to rule out the possibility of a machine that basically sucked mass out of one black hole and deposited it into another very close by. [Answer] Really, we have no idea what happens in a black hole [because light cannot get out](https://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-black-hole-k4.html). So just say they can with weird future tech, that uses their structure, and you will be fine. I would go with: > > They are made of substance X, that instantly explodes when ray Y is shone in causing the whole thing to explode in an outward expansion of spacetime, which allows the two halves to escape each other. > > > Also make them alive ⚕️ to make them more interesting. > > > [Answer] HDE 226868's answer is completely correct. But what if we took two black holes in the process of merging and added a third black hole? The first two would be just below each others' point of no return but still circle around one another. Viewers from the outside would just see a black hole with a lengthened shape rotating very rapidly, using indirect methods like laser scanning. Now a third black hole of similar proportions as the other two together flies by at speeds close to the speed of light (let's say they are all three meeting in the center of a large group of black holes, and have been accelerating towards that group for millions of years, with some 'lucky' gravitational slingshotting by other black holes on multiple occasions). The third black hole flies just by the two other black holes, with their event horizons overlapping slightly. This would be a little bit like an unstoppable train hitting an inmovable wall, so the maths are a little beyond me. But I think we might not only get a gravitational slingshot effect strong enough to separate the two formerly joined black holes, but also the creation of a completely new fourth black hole where the three black holes overlapped, with the weight which the three original black holes lost in the encounter (probably just a small fraction of the three bodies - small enough to turn into a neutron star or an exploding cloud of protons). Entropy would continue to increase normally, as the black holes would all be moving very slow now (with a good chance of merging eventually). ]
[Question] [ Is there a habitability zone between the primary and secondary stars in a binary star system for a planet orbiting only the primary star at a distance less than that of the secondary star and, if so, what is the greatest energy output of the secondary star (in terms of energy received by the planet) that would permit the habitability zone? * Assume the primary star is equivalent to Sol. * Assume the planet is equivalent size and mass of the Earth. Consider a 3D chart: * The X-axis is distance of the secondary from the primary. * The Y-axis is the energy output of the secondary * The Z-axis is habitability (0-100% liklihood of a habitability zone) I can easily assume that as X approaches infinity habitability approaches 100%. Further, I can assume that as Y approaches zero, habitability approaches 100%. It's the space in between that I'm having trouble understanding. [Answer] # Yes, there is a habitable zone. ## Known examples of possibly-habitable binaries I have to disagree with [StephenG's answer](https://worldbuilding.stackexchange.com/a/105611/627); we have data that indicates that this is possible for similar, Sun-like stars. I talked about this in [an answer I wrote a few months ago](https://worldbuilding.stackexchange.com/a/111887/627); searching [this exoplanet catalog](http://www.univie.ac.at/adg/schwarz/binary.html), I found several systems that might be of interest: * [WASP-94](https://arxiv.org/abs/1409.7566), a pair of F-type main sequence stars, each with a close hot Jupiter orbiting it. * [HD 20781](https://en.wikipedia.org/wiki/HD_20781)/[HD 20782](https://en.wikipedia.org/wiki/HD_20782), two G-type stars, each with 1-2 planets (one at 1.3 AU orbiting HD 20782, two at <1 AU orbiting HD 20781). * Kepler-132, a pair of G-type main sequence stars, although the structure of the system has been disputed. * [XO-2](https://en.wikipedia.org/wiki/XO-2_(star)), two cool K-type stars, with a confirmed hot Jupiter around one star and two possible planets around the other. The HD 20781/HD 20782 system has me quite excited. Both are G-type stars, and each star has at least one planet within 2 AU of it. The planets are all more massive than Earth, but that's immaterial; the important thing is that the binary stars have a separation of 9080 AU! That's enormous, and it's absolutely enough for there to be relatively little effect on each planet from the other star in the system. Some things to note: * HD 20782 b has a large eccentricity, and HD 20782 b and HD 20781 c also have larger eccentricities than normal, which could be due to the binarity of the system. The XO-2 system's planets seem to have smaller eccentricities, even though their separation is a mere 4600 AU. * In most of these systems, both stars are extremely similar in spectral type, which seems like a good thing. They're relatively Sun-like, not active red dwarfs or hot massive stars. * StephenG's requirements of a large separation is easily satisfied in several of these cases, by an order of magnitude or two. Given the inverse square law for flux, I would expect the contribution from the second star to be many orders of magnitude lower than the primary; it's essentially zero. ## Calculating the habitable zone I did some modeling ([Python 3 code on Github](https://github.com/HDE226868/Binary-habitability)) to give some numerical support to this answer, so I wrote a program that generates habitable zones around binary systems, with certain assumptions: * Both stars are on the main sequence * The stars' orbits have zero eccentricity * Any exoplanet orbiting the stars won't be massive enough to influence the stars' orbits, and the system is stable I defined the habitable zone as the region where water is liquid on the surface of a planet. In other words, the planet's [effective temperature](https://en.wikipedia.org/wiki/Effective_temperature) - not taking into account greenhouse effects - must be between 273.15 K and 373.13 K. The formula for the effective temperature of a planet in a binary system is $$T=\left(\frac{1-a}{4\sigma}(F\_1+F\_2)\right)^{1/4}$$ where $a$ is the albedo of the planet and $F\_1$ and $F\_2$ are the fluxes from the stars. Here are three basic plots, of a single Sun-like (G2V) star, two Sun-like stars separated by 2 AU, and two Sun-like stars separated by 5 AU. All assume a planetary albedo of 0. The habitable zone is shaded in black (the precise temperature is not shown): [![A single G2V star](https://i.stack.imgur.com/J5BOI.png)](https://i.stack.imgur.com/J5BOI.png) [![Two G2V stars, separation 2 AU](https://i.stack.imgur.com/d8TK7.png)](https://i.stack.imgur.com/d8TK7.png) [![Two G2V stars, separation 5 AU](https://i.stack.imgur.com/zS0XY.png)](https://i.stack.imgur.com/zS0XY.png) The effects from the second star are apparent with the 2 AU separation, but not with the 5 AU separation (although I can confirm that they're there). The form of the effective temperature formula means temperature only varies as $T\propto F^{1/4}$, where $F$ is flux, and thanks to the inverse-square law, even a separation of 5 AU produces minor results. Here's a plot where the separation is 9080 AU, as in the HD 20781/HD 20782 system: [![A G3V and a G9V star, separation 9080 AU](https://i.stack.imgur.com/2Z4J6.png)](https://i.stack.imgur.com/2Z4J6.png) The other star is far off my screen. Zooming out makes it impossible to see. For the purposes of habitability calculations, each star is on its own. ## Orbital stability Now, a class of binaries I'm curious about are late-type dwarfs with relatively small separations (1-2 AU). Two M-type red dwarfs can orbit close together and still have their own individual habitable zones: [![Two M0V stars, separation 1 AU](https://i.stack.imgur.com/2Htv1.png)](https://i.stack.imgur.com/2Htv1.png) What I don't know is what the stable orbits are around these stars. I assume some stable orbits are possible for the above case, but I don't know the ranges, and would be interested to find out. Another interesting scenario is two K5V stars at 1 AU; their habitable zones are connected, but the zones are stable orbits may be much smaller: [![Two K5V stars, separation 1 AU](https://i.stack.imgur.com/VV3MS.png)](https://i.stack.imgur.com/VV3MS.png) [Answer] # Yes, and right next door [Weigert and Holman, 1997](http://www.astro.uwo.ca/~wiegert/papers/1997AJ.113.1445.pdf) concludes that > > The habitable zone for planets, as defined by Hart (1979), lies about > 1.2–1.3 AU (1′′) from α Cen A. A similar zone may exist 0.73–0.74 AU (0.6 ′′) from α Cen B. From our investigations, it appears that > planets in this habitable zone would be stable in the sense used here, > at least for certain inclinations. > > > This is confirmed more recently and with more powerful software in [Quarles and Lissauer](http://iopscience.iop.org/article/10.3847/0004-6256/151/5/111/pdf), 2016: > > Our simulations show that circumstellar planets (test particles), > within the habitable zone of either α Cen A or α Cen B, remain in > circumstellar orbit even with moderately high values of initial > eccentricity or mutual inclination relative to the binary orbital > plane > > > Reading through their paper, they simulated stability for > 1 billion years for particles in the habitable zones of both $\alpha$ Cen A and $\alpha$ Cen B (and also circumbinary orbits that would not be habitable). So, as far as we know, there exists a habitable zone between the primary and secondary of the nearest (non-red dwarf) star to us. $\alpha$ Cen A is very similar to our sun (1.1 solar masses, 1.5 solar luminosities, spectral type G2V just like Sol). The luminosity of $\alpha$ Cen B is 0.5 times that of Sol, so the companion can be pretty bright in these circumstancs. # How close can they be? To answer HDE's addendum/bounty, I fired up my trusty Rebound tool to find the closest orbits that suggest stability. I did a bunch of grid searches over various eccentricities, and the finding was that for the stellar masses below, eccentricity has relatively little effect (at least for low eccentricities < 0.1). The computational demands of this problem proved to be much higher than in previous questions. I tried to test 10s of thousands of cases over 1 million years, integrating with a time step of 0.001 years (about 8 hours). I found some interesting cases and some generalizations about behavior, but take these answers with a grain of salt. 1 million years isn't enough to prove anything. ### Case: Two stars, both of 1 solar mass Here we have some very interesting behaviour. Some planets will break out their orbit and orbit the barycenter of the system. Starting with the companion 3.5 AU from the primary, planet 1 AU from primary, and all orbits with 0 eccentricity, the planet did a horseshoe orbit at ~0.87 AU from either star for a million years. It was actually very close to the setup in [this question](https://worldbuilding.stackexchange.com/questions/62948/season-cycle-that-would-occur-on-a-habitable-planet-that-orbits-two-suns?noredirect=1&lq=1). For the case of the companion star being n AU away from the primary, the effects on the planet are: ``` 0 - 3 AU Planet is quickly ejected 3 - 4 AU Planet achieves an eccentric but stable orbit near the habitable zone 4 AU + Planet achieves a stable orbit outside the habitable zone ``` The real finding here is that for suns of equal size, a planet is likely to end up near the barycenter of the two suns. The planet also very quickly achieves stability in the equal-mass sun setup, whereas in the following examples, the orbits are chaotic for more than a million years. I would suggest that in order to get the planet in an orbit in the habitable zone of the one of the suns, you would need to add other planets to the mix. ### Case: Two stars, one of 1 solar mass, one a large red dwarf (M1V, m = 0.5 Sols) In this case, there are a good variety of stable orbits once the companion is at least 5.5 AU away from the primary. I didn't find any orbits that were stable in the habitable zone, though. Stable orbits for the planet tended to start about 2.5 AU away from the main, in some sort of resonance with the companion. Unfortunately, my 1 year old powered off my computer before I could read the final results of the 8 hour grid search for stable outer orbits. That is what you get for writing to the console and not a file. Whose idea was it to make power buttons have LEDs anyways? Those things are toddler magnets. For the case of the companion star being n AU away from the primary, the effects on the planet are: ``` 0 - 3.5 AU Planet is quickly ejected 3.5 - 5.5 AU Planet enters eccentric orbit in vicinity of habitable zone. May be eventually ejected, unlikely to be stable in habitable zone. 5.5 AU + Planets in the habitable zone are pulled outwards into resonances with the companion star ``` As with the last simulation, planets tend to be pulled towards the barycenter. This suggests that additional planets maybe necessary to straighten out eccentricities. However, it is also worth noticing that this simulation is close to the ones cited above related to Alpha Centauri, and it does not replicate the results. So, perhaps an extra big grain of salt needs to be taken with this entire endeavor. ### Case: Two stars, one of 1 solar mass, one a small red dwarf (M6V, m = 0.1 Sols) Beyond 2 AU from the primary star, the companion star is too small to immediately eject the planet from the system. However, almost all of the orbits I plotted remained unstable for 1 million years, implying that they will eventually lead to ejection (or collision with the primary star! which did happen in one case). The two important relationships appeared to be the distance of the barycenter of of the system from the main star, and orbital resonances between the companion star and the planet. In general there were the following zones of interest based on distance between the primary and companion: ``` < 2 AU The planet is quickly ejected 2 - 4.5 AU The planet finds a somewhat stable, but highly eccentric orbit 4.5 - 5 AU The planet quickly enters a stable orbit at ~0.55 AU 5 - 9 AU The planet enters an eccentric orbit, and may stabilize in a resonant orbit with the companion 9 - 12 AU Same as above, but the barycenter is in the habitable zone, so a stable orbit there is probably impossible 12 + AU The planet enters an eccentric orbit, and may stabilize later (none of these did within 1 million years) ``` I did not find a single orbit of the tens of thousands tried that ended up stable in the habitable zone within 1 million years. However, the 5-9 AU and 12 + AU cases both contained eccentric orbits with roughly the correct semi-major axis, so it would be possible for these to stabilize out given enough time. # In progress [Answer] Not for two large, similarly sized stars, maybe for one large star and one dwarf star (like a [brown dwarf](https://en.wikipedia.org/wiki/Brown_dwarf)). The former case would not allow a stable orbit to form for long enough for the planet to develop a reasonably consistent climate (essentially driven by a nearly constant level of solar energy) over a period large enough to develop life. The case with the brown dwarf (a very dim type of star) can be though of as a system with a very large Jupiter that's still much smaller than the Sun, and with a much, much lower energy output. Such a brown dwarf could, in principle, be far enough from the planet to not greatly affect it. There is a quantity known as the [effective temperature](https://en.wikipedia.org/wiki/Effective_temperature) which let's us estimate the approximate temperature effect of a star on a planet. We can use this to relate the effect of the smaller star (the secondary) on the temperature of the planet (dominated by the primary, for stability). We get a formula like this : $$\frac {T\_{sec}}{T\_{prim}} = \left( \frac{L\_{sec}D\_{prim}^2}{L\_{prim}D\_{sec}^2} \right)^{\frac 1 4}$$ where the $L$ values are luminosity of the stars and the $D$ values are distance from the planet. We want this to be a small number, like a percent or two at most for a reasonably stable climate. So some very rough order of magnitude calculations : Now a possible value for $L\_{sec} \approx L\_{prm} \times 10^{-3}$, and if we set $\frac {T\_{sec}}{T\_{prim}} \approx 2 \times 10^{-2}$ (about a 4% variation in temperature due to the secondary), we get : $$D\_{sec} \approx 79 D\_{prim}$$ So the secondary has to be about 80 times further from the primary than the planet is. Both would be in roughly circular orbits at these ranges, and the brown dwarf could be of the order of about 50 Jupiter masses. These are, of course, ballpark figures. [Answer] First, to help clarify the orbit in the question posted, according to [arXiv:0705.3444](https://arxiv.org/abs/0705.3444) that planets orbiting a single star within a binary system, is called an ‘S-type’ orbit (while a circumbinary orbit is of ‘P-type). This paper [S-Type and P-Type Habitability in Stellar Binary Systems: A Comprehensive Approach](https://arxiv.org/pdf/1303.6645.pdf) explores various scenarios and their effect and limitation on possible habitable zones for said S-Type planets, though in heavily math-based, less conceptual-based terms. However, as regarding to the orbital stability of an S-Type planet, Solstation.org on [this](http://www.solstation.com/habitable.htm) page, referred other papers when indicating that planets with orbits that are less than 1/5 the closest approach of the secondary star are generally stable. It also mentioned that there were existing observed binaries in which dust rings and possibly planets appeared circling only one star, though far fewer exist in binaries with intermediate separations between 3-50 AU (below 3 AU there were some circumstellar P-Type rings) and it's above 50 AU that the S-type rings around a single star were observed). So, the limitation on habitability is primarily restricted by the requirement of a steady insolation falling on it, not the stability of its orbit. Also, if you use StephenG’s equation as a ball park estimation, the closest the secondary star can be to the primary for various luminosities can be determined (with equal ball park accuracy) by maintaining the value in parenthesis. Therefore, as your change the luminosity of the secondary star L$\_{sec}$ by a given percent, you have to change its distance (~80$D\_{prim}$) by the square root of that percent (i.e. quadruple the luminosity of the secondary and it now has to be twice the original distance of about 80$D\_{prim}$ to maintain the same relative insolation - up to some maximum limit below the primary’s luminosity, which I was not able to determine from the paper and not stated directly in it). Though it showed mathematically why equal stars could not support a habitable planet. ]
[Question] [ I have been designing a species of elves with blue skin as one of their most striking features. I'm drawing inspiration from primates that also have blue skin. Think the scrotum of a vervet monkey, or the buttocks of the mandrill. According to this article,(<http://jeb.biologists.org/content/207/12/2157.full>), the color is caused by light scattering through special layers of collagen. This layer can be 800-1500 micrometers (0.8-1.5 mm) in the areas described. As an adaptation to produce and support this amount of collagen, I'm giving the ability to synthesize their own vitamin C, a somewhat carnivorous diet, and a higher haemoglobin count to improve oxidation to the dermis. I'm considering having them sail and hunt in the ocean, since they would be effectively immune to scurvy. However, Human skin ranges from 0.5 to 4mm in thickness, so my hypothetical elves may have much thicker skin. My questions are follows: what impact would having this thick layer of collagen in the skin be on the elves everyday life? Could there be deleterious effects? And finally, are the adaptations I have listed enough to combat the potential problems? Edit: as far as ’deleterious effects'go, the ones I can think of would be stiffness in the face and possibly a higher likelihood of forming scar tissue, though feel free to suggest more. [Answer] The method you are proposing is already a human disease called scleroderma. It consists of excess collagen in the dermis (the soft tissue immediately under the epidermis, what we usually consider "skin"). Scleroderma leads to thickened skin, which will reduce flexion and can paradoxically increase skin fragility and cause poor healing. Most of the worst effects of scleroderma can be mitigated if the collage is ONLY in the dermis, not in internal organs. This seems to be a complex way of approaching the goal of having blue skin. There are many pigments which can produce a blue color, just because few are found in current mammals doesn't mean that it can't happen. From an evolutionary perspective you just need a good reason for mammals to be blue and evolution will eventually select for that pigmentation. Another option is that these blue elves engage in some sort of environmental contamination that gives them the blue color, much like how flamingos are pink only if they eat the correct food. In this case any elf sharing this part of their culture would be blue, and any blue elf denied that part may eventually lose the blue tint. [Answer] Human skin thickness is also a consequence of local wear. I remember reading somewhere the account of a castaway, who, after living years on a remote island and necessarily walking barefoot, had developed such a thick foot skin that he could walk on spiked rocks without the need for shoes. The only problem I see is that the blue and thicker skin will also somehow affect the amount of UV radiation which can be used to produce vitamin D. And lack of vitamin D has important consequences. This can be a limitation only if your elves live very far from the Equator, where the amount of light they can get is low. EDIT: After Bret's comment, and considering you stated they live of fishing, lack of vitamin D is a minor issue. [Answer] According to the linked article I can see that blue body parts have no hair or have very little of it. My guess is that this additional layer of collagen may somehow prevent hair follicles from appearing there. Also, our skin's outer layer is basically dead cells. Cells from deeper levels of skin are constantly reproducing to restore the outer layer. For each dividing cell its "children" go upper and... die there, creating a protective keratin protein. If there is an additional collagen layer it may affect the restoration process. I believe that this blue skin will regenerate and renew itself at lower rates, it might become quite delicate and sensitive even though it's thicker, because there will be less of keratin. [Answer] Skin that's too thick could present problems with temperature regulation. Blood vessels would be too far from the surface of the skin to lose heat effectively to the air. A way to circumvent this would be having your elves live in permanently cold climes so they wouldn't need to lose heat in the first place. ]
[Question] [ I’ve been thinking about flag designs for colonies on Mars, and something occurred to me. ## The “official” [Flag of Mars](https://en.wikipedia.org/wiki/Flag_of_Mars) has a critical flaw The average wind speed on Mars is 10 m/s (20 mph); the fastest speeds recorded by the Viking lander were 30 m/s (60 mph), barely half the speed of hurricane winds on Earth. More importantly: Mars’ atmosphere is just 1% the density of Earth’s. These factors combined mean one couldn't fly a kite there. ## A flag flying on Mars According to what I’ve read, winds of about 5 m/s (11 mph) are needed (on Earth) to get a flag flapping. In Martian terms, that’s wind at 50 m/s (111 mph). (Dynamic pressure of the atmosphere needs to be multiplied by about ten for Mars’ wind to be comparable to Earth’s.) That’s certainly above the average-to-high range for wind on Mars. So no, Pascal Lee’s Martian tricolour couldn’t actually fly on Mars. ## Changing the proportions In flag terms, the wind velocity needed to overcome the drag coefficient increases as the length (fly) increases over the drag (hoist); in other words the longer a flag is, the stronger the wind must be to make it unfurl. Shorten the length/fly and you lower the required velocity. That suggests a flag shape with a much shorter length/fly than typically found on Earth. The actual math for calculating this is a bit above my ability, but it makes sense that if wind pressure on Mars is a tenth of Earth’s, a flag with a tenth the length/fly should flutter on Mars the way its full-length counterpart on Earth would. (Lighter, thinner material would obviously have an easier time too.) Of course that means you could just have a tiny square for a flag, but that rather reduces its visibility at a distance, and would restrict how complicated the designs could be. So I propose the ideal proportions for flags flown on Mars would look more like [nobori](https://en.wikipedia.org/wiki/Nobori) than your standard modern flag: 4+:1. Tall but narrow; probably no more than 25 cm (10 in) across, but no less than a metre tall, if I had to guess. (Ideally Martian flags would not need the cross-bar used in nobori, but flags made too large or of materials too heavy wouldn't have a choice.) ## Bonus: What that means for the design of Martian flags I suspect not much would change. Lee’s tricolour design, if rotated 90°, would definitely work. Horizontal stripes and divisions of the field would be as common as on Earth, but vertical divisions and stripes might be more easily obscured when at rest. Use of charges and emblems may similarly depreciate as the narrowed fly would require proportionately smaller designs. Cantons would likely occupy the full width at the top of the hoist, and chevrons might point down from the top. Bends and saltires would still work, and Nordic crosses could be rotated, but the vertical bar of any cross design could be a problem if it isn’t a significant width of the fly. # The question(s): Do the numbers work out, and if so would the suggested change of proportion be the best solution (not requiring a cross-bar)? Bonus: am I overlooking any ramifications for flag design within these constraints? [Answer] Use a lighter cloth. The reason we use such heavy cloth on Earth is so it has some longevity in high winds and rain. That's not a problem on Mars so you could use much lighter weight materials. You're usually looking at [materials that are 85-160gsm](http://www.corradflags.com/how_is_a_flag_made/flag_material/flag_material.html) to make a flag. You probably want something around 10-20gsm, equivalent to tissue paper, which appears to be within standard cloth manufacture ranges. This would be shredded by normal winds on Earth, but should be about right for Mars. [Answer] Does a flag have to wave in the wind? Consider the more general case of vacuum or other arbitrary conditions. Will the flag only be displayed on Mars, or will embassies etc. want to display it elsewhere? So maybe it should be feestanding like a sign. It may have animation as part of the design! So it is presented in active media, not a dumb cloth. Whatever attention grabbing feature will be designed in directly, not reliant on the wind as a crude driver of visual change. [Answer] You can't fly a kite on Mars but balloons should still work. Just make parts of your flag inflatable and fill them with a very light gas. If you segment the inflatable part of your flag along its horizontal length, and hinged each segment to those before and after it along that length, then the flag would even wave as the lightweight winds hit it. [Answer] Flags aren't necessarily rectangular, consider [pennants](https://en.wikipedia.org/wiki/Pennant) or their variants, as in the [flag of Nepal](https://en.wikipedia.org/wiki/Flag_of_Nepal). Or go for a 3D flag by loosely tying the outer end, like drawstrings around the mouth of a bag, to make a [windsock](https://en.wikipedia.org/wiki/Windsock). Standard windsocks are fully extended at 17kph, so around 5 m/s, so that should be adequate given the average wind speed on Mars. The best part, the flapping effect is now due to the mass of air moving through the cone. [Answer] Domine Satanas beat me to the punch, but I was also going to suggest, using a different flag material. If an Earth flag is made with a certain amount of density and mass, you would need to also scale this down so that it adjusts for the proper wind and density of the air. Instead of using very heavy and dense fabric, what about a lighter cloth one similar to T-shirts? Or make up some synthetic material designed specifically for the air density of Mars. When it comes to the density (Density = Mass/Volume), we also have to think about mass of an object. The less dense an object is, the less mass it has, the less force would be required to move it. force (Force = Mass x Acceleration). So by reducing the mass, you can also account for the reduction in acceleration applied to the flag by the wind. If you want to keep the heavy fabric that Earth flags are made out of, you will need to shape the flag so that it can gain more surface area to catch the wind. Think of sailing. The bigger the sail, the more surface area it has, the more wind it can catch, and the bigger the boat that can be made to move and or the faster the ship can travel. Since our flags are designed to catch wind with our atmosphere, you may find it that you will need to increase the size of the flag and possibly add pockets to to help the flag catch wind. The other thing to consider is that gravity on Mars is only that of 38% of what it is on Earth. In other words, if you weigh 100 lbs on Earth, you would weigh 38 lbs on Mars. This means that even though there is less wind and atmosphere, the flag by ratio, would also be significantly lighter compared to the same flag on earth. [Answer] Don't use a common flag pole but let it hang down from a horizontal bar. Your flag will always be displayed properly and it will also wave in the wind. But still, the cloth has to be as light as possible. [Answer] Even on Earth, there may be need to make flags fly steadily or flap at the right rate instead of merely hoping that they do. Outside when there isn't enough wind, or inside where there probably isn't any wind. Such a flag would have to be made of two pieces of cloth or plastic, one for the obverse side and one for the reverse side. And there would be stuff between them to make the flag fly and flap. For instance there could be tiny horizontal tubes that run the length of the flag, each with a tiny fan at one end. When the fans were not running, the flag would only fly and flap as much as the current wind made it. When the fans were all turned on to full power they would blow enough air through the tiny horizontal tubes to inflate them and make them stand stiff and horizontal, pulling the flag into a a stiff horizontal display. And when the fans were turned on and off at different rates and combinations, the flag would flap like it was in the wind. Another possibility would be to put tiny electromagnets in the space between the two sides of the flag. Electromagnets with the same charge repel each other. So if the electromagnets have the same charge and given full power they will repeal each other strongly stretch out the flag to a stiff horizontal display, if they have no charge the flag will hang limply without any wind, and if they are given power levels that vary with time the flag will flap. Of course such flags will need computer controls and power supplies. [Answer] You want the flag flapping free. Intead of having wind do it, maybe have an automated "flag flapping tentacle arm" in the flag to simulate wind? If you don't want a tentacle flag, maybe make it from a super light plastic, like saran wrap, that's been art'ed up? [Answer] Forget the math entirely. Just give your Astronauts Augmented-Reality HUDs in their helmets, and render the flags digitally. There's more than one way to skin a cat. ]
[Question] [ Carbonfiber is said to be lighter and stronger than steel. Would it be a material of choice for building swords in modern times? Disregarding price, is it possible to make it as sharp as a steel sword? Would it shatter upon impact with something hard? [Answer] Carbon fibre and many of the super materials that have been developed in the last several decades (Kevlar, Spectra, M5 and so on) are generally fibres which are amazingly strong in tension. While this has many fantastic properties, this by itself isn't going to help you make a sword. To illustrate, think of the fact that spider silk is something like 17X stronger than steel by weight. A strand of spider silk can take 17X more force in tension than a similar strand of steel of equal weight. OTOH, trying to make a sword of spider silk will result in a large, floppy mess. You will probably be able to successfully entangle the opponent with such a weapon rather than slicing him in half. Most carbon fibre items like skis, arrows, car doors, 787's and so on are composites, which use carefully aligned bundles of carbon fibre to provide strength in tension, and other materials to provide strength in compression. Composites also need a strong binding material in order to keep the fibres in place (traditional boat makers will recognize the goopy resin used to keep the glass fibre in place). Since a sword (or most striking/cutting weapons) require strength in compression, carbon fibre by itself would not make for a useful sword blade. A composite blade could be made as a "sandwich" of a central steel cutting blade and carbon fibre "slabs" on either side to provide a very stiff, lightweight blade. As an aside, the traditional Katana was a very complex 3d object which also used a sandwich of hard, brittle steel in the middle to hold the cutting edge and softer steel on either side and on the non cutting "back" edge to provide flexibility and the ability to absorb blows without the blade snapping, so a composite sword could be "tuned" to provide different sorts of performance (a rapier like blade would benefit greatly by being stiffened by a lot of carbon fibre, while a traditional longsword used the weight of the blade to provide more of the motive and cutting force through chain mail armour, so a lighter longsword might not be as effective beyond a certain point). So if your aim is to make or deploy a composite blade, study the nature of the fighting style and the sorts of armour/defense it was supposed to penetrate to understand why the blade is built the way it was, and then work with that. There is a reason that different cultures and time periods used different types of swords. [Answer] It depends on the characteristics of the sword. Remember that carbon fiber composite (CFC) is made up of carbon fibers held together by epoxy (genetally speaking). To get a fine cutting you'd be sharpening the epoxy which is a bad cutting edge. When a sword strikes something, it experiences impact forces. CFC has very poor impact resistance. It will delaminate. In tension, fibers carry the load so it is very strong and in compression, the epoxy carries most of the load so it is weaker. CFC is lighter so the strikes will have less energy in them. Now with these limitations in mind, you could probably build a katana with using CFC as the core. Then have Kevlar composite on the outside. Kevlar has better impact properties than CFC. The cutting edge could be of any metal of choice that can be sharpend. The blunt edge could be of some high strength steel. The use of a sword like this would probably be for speed and agility due to it being very light. Blocking a strike or striking a hard surface such as armor can damage the composite. This means that this sword would probably require precise cuts in strategic locations like on unarmored locations or between armor platings. [Answer] Swords require good values in many primary properties (hardness, toughness, tensile strength, compressive strength, & shear strength) and benefit from good values in other secondary properties (corrosion resistance, cost, durability, etc.). The super material fibers mentioned above possess fantastic values for a single property (tensile strength) but possess significantly worse values in the other primary properties (hardness, toughness, compressive, etc.). The reason we still use steel instead of other materials is because generally speaking it provides the best over all performance of the materials we've tried. I do think that modern materials science could "build a better sword" now but I'm not sure anyone has spent significant engineering design effort figuring out what the ideal blends of materials are and how to composite them for best effect. @Youstay Igo mentions a titanium cutting edge and this might be a good addition (titanium has high hardness). But can we do better? Some things to consider: * Hardness on the point & cutting edge * Toughness in the center & on edge opposite of cutting edge (for single edged swords) * Ideally cutting edge kept in compression by means of carefully cycling between heating, quenching, and annealing the sword. * Composite fibers (which ones?! [Boron Nitride fibers](https://en.wikipedia.org/wiki/Boron_nitride#Properties) possess fantastic material properties but are exceedingly hard to work with) may be used to strengthen the portions of the sword in tension. * Cutting edge might benefit from the application of [ceramic coatings (synthetic sapphire or diamond?)](http://www.gavish.com/sapphire-coating-metallization.htm) * Steel would be our starting point and we'd look for materials that could outperform steel in specific roles (e.g. [high nickel "super alloys"](https://en.wikipedia.org/wiki/Superalloy) might possess better mechanical properties than typical sword steels). [Answer] About the sharpness, specifically: Not unless coated with something else. A carbon fibre material is nonhomogenous, and any refined edge put on it (if you even could - see below) would very quickly degrade due to impact or wear having an uneven effect on the constituents of the material. The sharpness of real world knives is actually limited by the choice of steel alloy, since homogenity of a steel differs depending on alloy and heat treatment - a satisfactory razor or sashimi knife can be made from fine grained steels like 13C26 (stainless) or pure carbon steels, but not from eg D2 tool steel or conventional (non powder metallurgical) HSS steels since it is practically very difficult to abrade a material that has coarse, very hard inclusions evenly enough and keep it even. That said, many sword types do not depend on being as sharp as the material would allow. [Answer] [This forum](http://www.swordforum.com/forums/showthread.php?65693-Carbon-fiber-sword) suggests it is possible to build a carbon fiber blade but deems it a bad choice for swords. > > Question: Would it be possible to make a good sword out of carbon fiber? Would it keep an edge and be flexible enough? I am interseted to see how this will work out because carbon fiber is so light. Thank you in advance. > > > > > [This Q-A](https://www.quora.com/Would-a-sword-made-out-of-carbon-fiber-be-effective) also suggests that a CF blade would be sturdy and long lasting, but not much effective at slicing and dicing. > > Question: Would a sword made out of carbon fiber be effective? > > Answer: It would depend on the type of "effectiveness" you require. Probably fine for stabbing. Hard to say about slicing. Steel could probably be worked and sharpened to a finer edge which is less fragile than ceramic kitchen knives. It would depend how sharp you could make the carbon fiber, and whether it would shatter if it hit bone. > > A great samurai sword is worked and folded with two kinds of steel, one more flexible, one less. Could you toss a red silk up in the air and part it when it lands on a carbon fiber sword edge as in the Kevin Costner/Whitney Houston movie? Try it and see. > > > Most sword builders on the web indicate that if you get the edge on the blade made of titanium and keep the rest of blade carbon-fiber, that would be the best sturdy, slicing sword you could get with modern tech. [Answer] The only purpose I can see a carbon fiber sword for; is a bokken/bokudo, and it would probably need an aluminum core. It possibly would be more prone to shattering, than the cheapest wood bokken, and you don't want CF to shatter. The aluminum core would add a flexible strength to it, because CF does bend under stress, it is normally stiff, not being xesigned to bend. CF bike forks are some of rhe stiffest out there, and they're hollow, so on could only imagine a layered "folded" CF bokken; shaped, then ot only vacuum formed, but with a bit of heat. I imagine more deadly than a baseball bat, with quick consequtive hits, especially if one has trained with heavier swords(wood or metal). ]
[Question] [ Now I know that there are limits technically on size of plants as seen in [this post](https://worldbuilding.stackexchange.com/questions/463/what-is-the-limiting-factor-for-a-plants-growth/), but what I want to know is what limits a plants speed? I'm guessing it has to do with the soil, but is that all? The reason for this is to create a jungle or forest that regrows within minutes of utter destruction in a wide area from a orbital barrage. There would be some left like bits and pieces, but otherwise mostly destroyed. Is that possible or just a magic handwave moment? [Answer] Well [Bamboo](https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1CHFX_enUS603US603&ion=1&espv=2&ie=UTF-8#q=fastest%20growing%20plant) is the fastest growing plant on Earth and it can grow (under ideal circumstances) up to 3 feet in a single day. The gardens in Alaska do so well because in the summer months they have 18+ hours of growing light available every day. The plants almost don't stop for 3 months! Some of the things that go into plant growth are sunlight, soil and water. Any plant needs at least these three things. The more sunlight and water available the more growing time a plant has. Soil providing what the plant needs is also very important. Now if bamboo can grow 3 feet in a day, and most of it grows in the tropics, so we'll say 12 hours of daylight growing time. that would be a foot for every 4 hours or 3 inches an hour. If the plants/trees have have a massive root system that stores the needed nutrients to grow when the plant body is destroyed, then you might be able to double that growth rate for plants evolved to such an environment. However, I expect there to be a physical limit to how fast cells can divide and grow. Since you still need to build the structure to support the plant as it gets bigger. [Answer] Limitations to plant growth are construction materials, growth conditions and available energy. If a plant has the capacity to grow 3 feet a day but the temperatures are sub-optimal and sunlight too weak, then growth won't near the maximum possible. Compare the growth of a plant to building a house. If the construction materials for the house aren't available then construction will slow down. If the workers are always tired because of lack of food then construction will slow. If it's too hot or too cold then the workers will have to spend more of their time cooling down or warming up thus slowing construction speed. To repopulate a devastated area has to deal with a couple of problems. If the devastation has sterilized the soil then the soil bacteria that facilitate growth will need to be put back. If the seeds for the plants have been killed then they will need to be redistributed. If the devastation has evaporated much or all of the water in the soil then water will need to be reintroduced. Some of these steps can be done concurrently but not in the time scale of minutes. That's magic. [Answer] There are three inputs to the rate at which a plant can grow. Nutrients from the ground (including water), carbon dioxide from air, energy in the form of sunlight. A plant will try to keep these in balance. If it's shaded it will grow more leaves than it would need just to absorb CO2 (and of course, it will grow towards the light). If it's got all it needs above ground it will expand its root system to fetch more nutrients. Both assume it hasn't yet reached its mature size. Sometimes the lack of a particular trace nutrient in tiny quantities will stunt a whole plant. Bamboo is a bit of a "cheat". It has prefabricated a large bud (a set of concentric cylinders) underground, in the months before it starts shooting up. It can expand upwards very fast by growing in much the same way that a portable radio's antenna "grows" when you pull it out. Other fast-growing plants are often moving pre-stored nutrients from below ground (bulbs, corms, tubers) to make new tissue above ground. Spring bulbs make a dash for it in early spring, grab sunshine, flower, set seed, and store all energy back into the underground bulb when the trees come into leaf and shade them. I wouldn't rule out something alien sprouting back in hours, if not minutes, provided it wasn't able to do that twice in rapid succession. What evolutionary pressure would cause this to evolve? Perhaps rather frequent forest fires (high oxygen atmosphere as well as high in CO2), and aggressive shading-out/ parasitism by other plants? I think your alien forest would be like a hybrid of the interesting features of bamboo and Japanese knotweed (and maybe mistletoe, venus flytrap, sea-anemone, yes that last one is an animal), plus a photosynthetic mechanism more efficient than that evolved on Earth, and maybe a hotter/brighter (blue) sun to power it all. Does it also eat insects? Small animals? People? A vaguely remembered sentence that I can't quite place: (name) disturbed a (name of large armoured herbivore), which scared him, so he climbed the nearest tree, which ate him". [Answer] There are some great answers here based on botanical and biological reasoning. I'd like to advance an even more basic physical consideration. Plants are made of matter and matter (well, matter plus energy) is conserved. So, how much matter constitutes a forest? Quite a lot. If that's supposed to spring back up in a matters of minutes, where is all that matter coming from? Yanking it straight out of the earth underneath sounds like you're gonna get a sinkhole. Pulling it out of the air will create a massive vacuum. There just isn't enough heat and light around to convert directly to matter since matter is so energy dense (the $c^2$ factor in $E=mc^2$ assures that). So it looks like a real problem in imagining conventional plants behaving this way. All that said, rather than raining on your parade, maybe you can roll with it and make some unconventional plants that circumnavigate the issue. Assuming that the forest does come back extremely fast, it can't have a lot of matter in it or we'd run into the problems above. So it must be of some sort of hyper-low density material. I'm envisaging plants made of a very airy, gossamer-like material. The plants could still be sufficiently tough to impede navigation (maybe they are poofballs of some carbon-nanotube kind of fibers) and opaque enough to severely limit visibility. [Answer] My understanding of terrestrial plant growth is that it is rarely limited (in the average case) by sunlight. Typically it is limited by availability of "biologically available nitrogen". After that it is probably limited by water or non-nitrogen nutrients (e.g. sulfur). Of course in some case the ranks can be reversed (e.g. in a desert water may be the limiting factor). If all required nutrients and H2O are over-supplied, then the limit to plant growth is the efficiency of photosynthesis in terms of the gain in energy from converting H2O and CO2 to carbohydrates and oxygen. Terrestrial photosynthesis requires light photons of the correct wavelength. It may be possibly to bio-engineer plants which can utilise more of the full spectrum of the suns light, but this would only help boost growth if natural sunlight is the first limiting factor. Likewise, it may be possibly to bio-engineer plants to use alternative photosynthesis mechanisms which are more efficient for a given light spectrum. This could be useful for alien plants or for plants grown in artificial space habs, but I doubt you could much improve upon existing terrestrial photosynthesis for growth in standard earth light. ]
[Question] [ From my understanding of animals, lifespan is all based on the speed of its metabolic rate. As endothermic animals, mammals live a high-octane life - growing up fast, being quick on activity regardless of the weather and demanding a lot of food in a short period of time. As a result, they, if you will, "live fast and die young". Ectotherms such as crocodiles, live life more slowly and leisurely and don't require as much food. However, since they can't create their own body heat, their personalities and environmental choices are limited. Regardless, this leisurely metabolism means that their lifespans get expanded. Then there's this recent popularity of great whites, tunas and probably dinosaurs being mesothermic, neither warm- nor cold-blooded, but bearing the advantages of both. You can still lead a high-octane life, but your body won't require as much food. One of the most popular characteristics of fictional hominids - like elves and dwarves - is a lifespan longer than humans. Which metabolism would be better suited for these primates, ectothermy or mesothermy? [Answer] While I agree with James' assertion that immortality isn't simple, I think it's worth mentioning that there most animals [repair their own DNA with telomerase](https://en.wikipedia.org/wiki/Telomerase) to remove errors -- and creatures with more telomerase (such as [lobsters](https://en.wikipedia.org/wiki/Lobster_longevity#Longevity), which express telomerase in most of their tissues) repair their DNA more efficiently, potentially living forever. While lobsters can't be immortal due to the high cost of moulting (which increases with the size of the lobster and the lobster is constantly growing throughout its life), there's no reason this couldn't be applied to a humanoid race -- your elves won't be growing too big for their skin. On the other hand, you could always have elves that "reincarnate" into their next generation, like the transdifferentiation in some jellyfish. [Answer] Aging is a lot more complex than simply metabolism or hot blood vs cold. In fact there are few vertebrates that live longer than humans and most of those are sea based, giant tortoises and some whales from a quick glance at the web. Its not metabolic rate that increases aging. We actually influence that rate with diet and exercise. People in great shape tend to be healthier, have higher metabolic rate and live longer. Aging comes down to our body being able to repair itself or not...in the case of aging. At a high level the process is this: Every time your cells replicate themselves there is a chance that an error will be made in the replication process at the sub-cellular DNA level. Its like the concept of making a photo copy of a photo copy until the original looks nothing like the current version. While your body does its best to clean up these errors, over time they accumulate and the body is less efficient, and less accurate about replacing old cells, thus we age and eventually die. [This is a decent high level article on the biology of aging](http://genetics.thetech.org/original_news/news10). [Answer] To echo the other answers, neither. It's entirely possible for warm or cold blooded creatures to have biological immortality. The thing is though that there is no evolutionary advantage to it. That may seem counter intuitive but consider that you need reproduction anyway to continue the species as otherwise you have no ways to increase your numbers or recover from disasters. That reproduction already works very effectively to reset the biological age and at the same time undo most environmental damage. If you lose an arm to accident or injury then your children are not born missing an arm. On the other hand building repair systems into an adult that are capable of regrowing an arm would be complicated (and potentially increase risks of cancer or infection and would certainly increase calorie requirements at a time where you are already going to struggle to acquire more calories due to the injury). Similarly healing without scarring would be possible, but is slower. It is not safe to take your time about sealing up a wound "in the wild". All of these factors mean that as far as our genetics are concerned we are already biologically immortal - through having children. There is no adaptive advantage to increasing our lifespans further than they already are. So creating an immortal is simple enough, you just need to be able to repair damage done to the body. Repair DNA, regrow limbs, heal scars, etc. The much harder thing to explain though is the evolutionary process that would make it worthwhile to develop that capability. ]
[Question] [ When you mention livestock you think of creatures such as cows, pigs, sheep, chickens and so on. We've been domesticating animals for like 17,000 years or so and have used them for a variety of means: meat, skins, labor and so on. But would something like this be possible with dinosaurs instead of the mammals we have? Of course, dairy's not an option with reptiles and using feathers from dinosaurs in lieu of wool from sheep will make the textile industry an interesting one. I'll buy that a nomadic lifestyle would be possible (ie, following the herds), but could a society like ours work with dinosaurs as livestock? I'm looking at all the various species of dinosaur which have actually existed, so no new species have evolved (but they can breathe the same air we do, eat the vegetation that grows here and are able to exist on the same world that we live on now). And for the sake of the answer, nasty carnivores can be seen as a non-issue (they're either chased off, exterminated or somehow domesticated). [Answer] You mentioned chickens, which are dinosaurs. So are emus and ostriches. There were many kinds of animals in the grouping lumped together as dinosaurs, some of which could prove useful: eat low-grade vegitation and produce meat; eat cheap materials and produce power for turning wheels or pulling loads; race for fight for sport; fight or defend in battle. Dinos filled many niches, as mammals do today. So there were a great variety. Some would be useful to us and presumably some of those actually exploitable, just like in the real world. Others would be dangerous or conflict with us, and eliminated. What makes an animal domesticatable? More to the point what precludes it? Is there any reason to think that primitive creatures would be less subject to domentication than even their modern decendants, for no other reason than being more ancient? Well, we farm alagators and fish, so no. [Answer] Are humans being transported to the mesozoic, or are we picking dinosaurs to come to our time? I`ll assume the former, since we already have plenty of of livestock species in our comfy Holocene period. The most likely species to domesticate would either be some of the smaller hadrosaurs or ornithopods. milk and wool would not be an option for these species, obviously, but some of them might have steady egg-laying cycles, so they could be used as giant chickens. Regular clutches of huge eggs would be an excelent source of protein at least as good as milk. Their size would also make them useful as draft animals. Of course, we have no idea of the temperment of these animals. Are any of them docile enough to domesticate? Will a pachycephalosaurus act like a donkey or a goat, or will it be completely unmanageable, like a zebra, or cape buffalo? The smaller troodontids like velociraptor might be domesticable in the same vein as dogs. But, you also seem to be asking whether we could overlap our modern society onto the mesozoic ecosystem. I`d have to say no. The one thing more important to the rize of civilization than the domestication of livestock is AGRICULTURE, specifically the domestication of cereal crops like corn and wheat. Flowering plants in general did not appear until very late in the cretaceous period, and grasses specifically did not appear until well after the dinosaurs died out. [Answer] If I remember correctly from childhood, the triceratops was a particularly non-aggressive animal, but would defend themselves if attacked. They could possibly be domesticated as guard dog type animals (of course if you're guarding against other predatory dinosaurs they may not be particularly effective). But if there are no bigger dinosaurs and they have been wiped out, that wouldn't be a problem. And they would be very useful for their horns, their hide and their meat if bred for slaughter. They could even possibly be ridden like horses, which would make them pretty good all-rounders. I think the answer is that some dinosaurs could be domesticated through training/breeding, as long as they are the more peaceful ones (and as long as you can build a fence big and strong enough to keep them enclosed). We domesticated wolves this way, and they're pretty aggressive, and now we have dogs, which (some breeds) are entirely non-violent. As for nomadic tribes with dinosaurs, with the dinosaurs being so much more deadly than humans (through sheer size) I would say that you would have to have dinosaurs that are already pretty ready to be subjugated in the wild (like cows), or that humans can offer them something that makes a mutual relationship beneficial for the dinosaur (such as protection from bigger predators). I would say the most dangerous dinosaurs, such as the T-Rex, couldn't be domesticated (could you train a shark to jump through hoops?) but could maybe be kept like a tiger in a zoo, as long as they're held properly. Of course, if you have modern technology you could always manipulate any dinosaur's genes to make them non-aggressive. [Answer] One thing that all large domesticated animals have in common is that they are herd animals with a hierarchical social structure, and domestication consists of breeding them to recognize humans as the herd leader. (This is why, for example, horses have been domesticated, while zebras haven't.) Keeping dinosaurs as livestock basically means finding a species that meets the above criterion, while also being useful (for meat, as a draft animal, and so on). Since the fossilization process doesn't preserve social structure, we don't know which species would be appropriate, but there are plenty to choose from. [Answer] I suspect the most likely sort of dinosaur to domesticate would be a smaller one of the Hadrosaurids (Duckbill dinosaurs). The triceratops and related species seem to have filled the ecological niche of bison, and would probably be rather aggressive, something you want to avoid in a herd of creatures the size of rhinos or elephants. The Hadrosaurids seem to have filled ecological niches closer to those of the herds of antelope or zebras on the African plains, and used herd behaviour to provide warning of predators, and sheer numbers to ensure a predator attack might be confused by the swirling mass of fleeing creatures (or at any rate the statistical odds of being killed and eaten would be low). The main issue with this is the Hadrosaurids would require an enormous amount of forage, and you could not effectively "ranch" them, you would need to let the herds roam across the continent in a free range pattern. This might be exciting for people who want to live the traditional cowboy lifestyle of the "Free Range Men" (a rodeo would be very impressive, especially the roping competition!). This would also mean that vast tracts of the great plains could not be inhabited by humans, but humans would have to ensure the vegetation and land was tended before and after the herd passed so there would be enough forage when the herd migrated back later that year. This also leads to the issue of what these creatures would eat. While the issue of atmospheric composition was asked (it was actually very similar to today), the sorts of vegetation that existed 65 million years ago was quite different. Grasses and flowering plants only came into being near the end of the age of dinosaurs, so modern plants might actually be poisonous for the Hadrosaurids. Replanting large areas of North America, Africa or the Russian Steppes with ancient vegetation might be far more trouble than it would be worth from the economic output of Hadrosaurid punching. ]
[Question] [ Given ideal circumstances and a type 4 or 5 [Kardashev scale](http://en.wikipedia.org/wiki/Kardashev_scale) level of technology to set the system in motion (but not to maintain the motion over time): How many planets 1/4 of the Earth's mass could share an orbit while remaining stable assuming there is an equal spacing between the worlds? If at least 4 of these objects could share an orbit, how many stable orbits could coexist within/bordering the [goldilocks zone](http://en.wikipedia.org/wiki/Circumstellar_habitable_zone)? [Answer] This problem [was solved](http://planetplanet.net/2014/05/23/building-the-ultimate-solar-system-part-5-putting-the-pieces-together/) by Sean Raymond. (Also [here](http://planetplanet.net/2014/05/19/building-the-ultimate-solar-system-part-1-choosing-the-right-star/), [here](http://planetplanet.net/2014/05/20/building-the-ultimate-solar-system-part-2-choosing-the-right-planets/), [here](http://planetplanet.net/2014/05/21/building-the-ultimate-solar-system-part-3-choosing-the-planets-orbits/) and [here](http://planetplanet.net/2014/05/22/building-the-ultimate-solar-system-part-4-two-ninja-moves-moons-and-co-orbital-planets/).) He calculated that you can fit four gas giants into a habitable zone. Each of them could have 5 planet-sized moons and a double-planet in both its stable Langrange points. Like this, you will get to 4\(5+2+2) = 36 planets. The gas giant planets are there to stabilize the whole system. You could still double the number by adding a second star in sufficient distance (100 AU) from the first one. So you would have two copies of this system, one for each star. We can ask how plausible is the stability of such system. The terrestrial planets orbiting the gas giants will be stable, since they are in the [Hill sphere](http://en.wikipedia.org/wiki/Hill_sphere) of much heavier body. Similar system is Jupiter with his Galilean moons. Double planets look also stable - double-planet is in a good approximation two-body problem, which is stable, and it is in the Lagrange point, which is stable place to be. (But we cannot rule out there would be some destabilizing iteraction between the gas giants and the terrestrial double-planets.) The most questionable factor is, if all four gas giants will fit into the Habitable zone. [Answer] It depends on the size of the habitable zone.* Whether or not a planet's orbit is within the (circumstellar) habitable zone (aka the Goldilocks zone) depends on a wide variety of factors determined primarily by the star. Here's the Solar System's habitable zone compared to the habitable zone around the star [Kepler-186](http://en.wikipedia.org/wiki/Kepler-186): [![Habitable zone comparison](https://upload.wikimedia.org/wikipedia/commons/c/c9/Kepler186f-ComparisonGraphic-20140417_improved.jpg)](https://upload.wikimedia.org/wikipedia/commons/c/c9/Kepler186f-ComparisonGraphic-20140417_improved.jpg) Image courtesy of Wikipedia user Bhpsngum under [the Creative Commons Attribution-Share Alike 4.0 International license](http://creativecommons.org/licenses/by-sa/4.0/deed.en). Here are some of [the factors](http://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Extrasolar_extrapolation) that determine whether or not a planet is habitable: * Luminosity of the star * Eccentricity of the planet's orbit (highly eccentric orbits, such as the one displayed [here](https://upload.wikimedia.org/wikipedia/commons/0/00/Eccentric_Habitable_Zones.jpg), may venture outside the star's habitable zone) * Temperature of the planet (yes, the planet's characteristics impact habitability) * Distance from the star (well, of course) * Whether or not other objects exist nearby which may destabilize the planet These are really just factors that impact habitability of a planet, but they show that just being in the habitable zone isn't enough. If your planet's atmosphere is such that it's too hot (like Venus), you're in trouble. If the orbit isn't stable because of other objects, or there is lots of debris in the area (e.g. asteroids), you're also in trouble. However, stellar luminosity is probably the biggest factor. In general, the habitable zones of stars follow the pattern shown here: [![Habitable zone pattern](https://upload.wikimedia.org/wikipedia/commons/4/46/Gliese_581_-_2010.jpg)](https://upload.wikimedia.org/wikipedia/commons/4/46/Gliese_581_-_2010.jpg) Image courtesy of Wikipedia user Henrykus under [the Creative Commons Attribution-Share Alike 3.0 International license](http://creativecommons.org/licenses/by/3.0/deed.en). However, there's a lot of error. We're not too sure of how far our own habitable zone extends, as can be seen [here](https://upload.wikimedia.org/wikipedia/commons/7/7b/Estimated_extent_of_the_Solar_Systems_habitable_zone.png). So it depends on a lot of factors. Next, I'll discuss our habitable zone. Our habitable zone looks like this: [![Our habitable zone](https://upload.wikimedia.org/wikipedia/commons/7/7b/Estimated_extent_of_the_Solar_Systems_habitable_zone.png)](https://upload.wikimedia.org/wikipedia/commons/7/7b/Estimated_extent_of_the_Solar_Systems_habitable_zone.png) Image courtesy of Wikipedia user EvenGreenerFish under [the Creative Commons Attribution-Share Alike 3.0 International license](http://creativecommons.org/licenses/by/3.0/deed.en). The dark green part is the range of conservative estimates; the light part is the range of liberal estimates. Look at the difference! I'll deal with the more liberal estimates, because they lead to more interesting scenarios. These mean that Earth, Mars, [Ceres](http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)) (a dwarf planet/asteroid) and the asteroid belt may all be inside it. Most models include Venus as well, as you can see in the second graphic in this answer. So three major bodies (Venus through Mars) and a dwarf planet can easily co-exist. Scale them down a little, and things are looking good. Venus is about the same size as Earth, and Mars is half as big. Ceres, though, is much smaller. However, I'm willing to bet that scaling it up wouldn't impact the others, although its proximity to the asteroids in the asteroid belt is worrisome. But for now, let's leave it in. So we can comfortably fit in four bodies. What about five? Well, if you move Mars in a bit, perhaps you could squeeze in a fifth. After that, though, things get dicey. You need to further decrease the distance between the planets. Six would probably be fine; seven is a stretch. Why? Because you have to account for orbital evolution. It's nearly impossible for eight (don't forget about Mercury!) terrestrial planets to form so close to one another, because the early chaos of the Solar System surely would have thrown some of their orbits out of whack. However, this Type IV or V civilization can easily do that. The trouble lies in maintaining long-term orbital stability, although perhaps they could adjust that. Still, perhaps you could put seven in the habitable zone, even if you let them be for a while. One last thing. As I'm typing this, Oldcat mentioned in a comment something I had planned to get to: > > I'm not sure any planet that size can hold an atmosphere in the habitable zone. Mars is .4g and it has its problems. > > > I don't know about Mars' problems with holding an atmosphere (although that by no means means that they don't exist). Wikipedia claims that the lack of a magnetosphere means that the solar wind can play an issue; whether or not that's true is up for debate, unless anyone reading this wants to go to Mars. Anyway, there is at least one example that shows that even a moon can hold an atmosphere: [Titan](http://en.wikipedia.org/wiki/Titan_(moon)), a moon of Saturn. Titan is really large - larger than Mercury, although not nearly as massive. [Its atmosphere](http://en.wikipedia.org/wiki/Titan_(moon)#Atmosphere) is more massive than that of Earth, although it's clearly not the same! So small bodies clearly can hold atmospheres. Admittedly, Titan is farther from the Sun than anything in the habitable zone, so it may not be subjected to strong solar effects. But it's something. I don't think it's likely that these small planets can hold atmospheres, but it's certainly possible. As for how many bodies could share an orbit - well, that's a bit complicated. I've been able to find [a question](https://physics.stackexchange.com/questions/25978/two-planets-in-same-orbit-not-planets) on Physics that talks about it, and it doesn't seem as if even two planets could share the same orbit. Here's something from Carson Myer's answer: > > I don't think the situation you mentioned is possible. You're describing two planets, each of which being in each others L3 points (a lagrangian point is a point in an orbit with special gravitational properties, where an object will remain somewhat stationary relative to the body whose orbit it's in). Even our comparatively tiny spacecraft which sit in Earth's L1 point (between the Earth and Sun) require periodic corrections. > > > Planetary orbits are somewhat unstable: they change by little bits over time, as the sun loses mass and as other planets and solar-system junk push and pull on the planets. If one of these planets' orbit changed just a tiny bit it would fall out of the lagrange point and into another orbit. The planets would begin moving at different speeds and would either collide or move into independent orbits in an astronomically short period of time. > > > So it doesn't look like four small planets could share the same orbit. [Answer] There was an earlier post about the moons of Saturn Janus and Epimetheus, that share virtually the same orbit. When they get close, the two swap orbits until the next encounter. This seems to be stable for them. So a 4 body solution for our Solar System would be 4 earthlike planets, 2 in Earth orbit and 2 in Mars' orbit. All should hold oxygen like Earth does and be suitable for life. ]
[Question] [ Say we're in a world where it is possible to tinker with biology as easily as it is to tinker with programming nowadays. For feasibility, refer to [How soon will tinkering with biology be as simple as programming is now?](https://worldbuilding.stackexchange.com/questions/4391/how-soon-will-tinkering-with-biology-be-as-simple-as-programming-is-now) Now computers answer many needs such as work, play, information, communication... Would there be any scenarios where such machine — a machine that is to biology what computers are to programming — would be desired in every house? And if not, how widespread would such a technology get? [Answer] Sure! Imagine a home device that lets you create a self-replicating solar or sugar powered autonomous intelligent mobile life form capable programmed to do exactly what you want? Customize your food, customize a pet, make a wasp that will hunt down that annoying fly in your room. The only limit is your imagination. I think it would have a lot of the same appeal as programming for yourself and 3D printing for yourself. Of course all this would require some pretty impressive tech behind it, but assuming it's there I think people would love the kind of creativity and power that such a device would provide. Here are some more examples of various uses I could foresee people using. Food: Customize the flavor profile, texture, and nutritional content of any plant, animal, or other organism. Also, synthesis of virtually any organic compound. Pets: Customize the size, shape, color, and behavior of your own completely unique pet. Art: Living art. Slime molds that sculpt themselves and other living, thinking, responsive art. Gardening: Related to art, imagine making your own flowers and other decorative plants. Any color and any pattern you can imagine. You can also customize animals to maintain your garden for you, kill any weeds or pests that show up, while watering and fertilizing. Cleaning: Keep your house clean with patrolling insects that dust and mop and automatically clean up any spills, (and of course keep out of sight while you are looking.) Hygiene: We have trillions of bacteria living inside of us and on us. Imagine a strain that will help whiten your teeth instead of yellowing it and give you nice breath while it's at it. A living perfume or antiperspirant would be a great replacement for our stinky armpits cultures. Even living makeup would be possible. Pest control: with all this rampant engineering some people are bound to make mistakes or play pranks. Unwanted organisms from the next door neighbor might be annoying and how else are you going to get rid of them but with organisms of your own? Communication: What better way to get a message out than with a mobile self-replicating living billboard? Something as simple as a pigeon with a company's logo or an anarchy symbol. These ideas would require an incredibly complete knowledge of how organisms work. But with that knowledge I see no reason why any of these possibilities are impossible. With complete control over the DNA sequence and a complete knowledge of what changes to that sequence will do the possibilities are endless. [Answer] This is my favorite question in a while, so I hope it's okay if I bend a slight rule in order to answer it. The question explicitly says "likely", so chances are my answer is completely invalid. I don't think there's much of a chance this would become likely anytime soon without some drastic change in the world. It goes completely against the question, but I'll explore some relatively un-likely scenarios. I'm in a rare creative mood, so here's a bunch of weird, wacky and completely (un-)likely scenarios: * [Cockfights](http://en.wikipedia.org/wiki/Cockfight) on steroids. I'm strongly against this kind of thing, and I'm fairly surprised it came to mind. Imagine underground, illegal leagues where animals are put together to fight it out. If you had these tinkering machines, you could change the DNA of your fighting creature in question to make it better. You could modify the creature over many generations. [Selective breeding](http://en.wikipedia.org/wiki/Selective_breeding) goes out the window. * Rampant, constantly changing diseases. Let's say you've got a world that's stricken with a plague that continually changes its structure, so it's nearly impossible for an organism to fight it. Perhaps you could use this machine (note: you probably couldn't) to modify your white blood cells (or at least their centers of production) to better fight off this illness. This assumes really poor medical care. * Weather is highly variable. If you have rapidly changing weather that goes from one extreme to another, it's going to be hard for farmers to grow anything. The solution: use this thing to make minor variations to the DNA of certain crops that make them resistant to different conditions, such as plentiful water or droughts, or hot and cold swings. Make different crops immune to different conditions, and plant them all. * Rapidly changing fashion trends. Well, fashion is important (sadly) in our society, too. But let's say it changes soon here. What do you do if your (genetically modified) purple hair become uncool? Change some genes to make your hair pink or green. Don't like your eye color? Change the genes for that, too. * Scientists are needed. Need a bunch of scientists? Inspire the kids early with this machine. Use it to inspire them by showing them the wonders of genetics. There's nothing like an amazing effect to inspire someone to do something. There are plenty of things to inspire people to go into science, but bringing the previously seemingly-abstract field of genetics right into people's houses would really inspire them. More to be added whenever they pop into my head. It's just going to be a fun little list. Note: Pretty much all of these things are highly unlikely. I'm taking a short break from science. It's quite relaxing. --- Edit: You really need circumstances where this device must be widespread. Here are some: * Back to diseases. I'll go back to my idea about diseases. Imagine a world where people are not densely populated. There's virtually no infrastructure, so it's difficult for people to gather. At the same time, there's a highly infectious and deadly disease that's constantly spreading (because people are so far apart, I'll imagine it's airborne). It constantly mutates, so people have a very tough time fighting it off. What do you do? Our bodies fight diseases with [antibodies](http://en.wikipedia.org/wiki/Antibody). These are proteins produced by [plasma cells](http://en.wikipedia.org/wiki/Plasma_cell) (which are produced in [bone marrow](http://en.wikipedia.org/wiki/Bone_marrow)) that latch on to certain proteins in an invader cell and help to destroy it. However, they are only useful against a certain version of a certain disease. In this world, that's a problem. The solution would be to use this machine to constantly alter bone marrow, producing different plasma cells to create different antibodies to fight different versions of the disease. * A changing atmosphere. What if the world's atmosphere is constantly changing? This would throw anyone's respiratory system into total chaos. How would a species survive? Once again, this machine would come in handy. Simply use it to modify some cells in the respiratory system that make the system able to process slightly different gases - for example, processing gas $XY\_6$ instead of $XY\_5$. If there are these constant changes in the atmosphere, the species could need this machine to survive. That - and some of the other ideas I've put forward - of course raises the question of how the species survived in the past. Perhaps there was some event (meteor, volcano, etc.) that changed the gases available for circulation in the planet's atmosphere, thus making it less stable. Unlikely but possible. This device would be very useful for dealing with infants, who are constantly developing and would have a hard time surviving in this changing world. Every family (especially those with children) would want this machine. This machine would be handy in a world where the environment is constantly changing, with otherwise dire effects on the population. [Answer] I don't think such a machine would realistically likely, but one scenario does leap to mind: As radioactive contamination of Earth and genetically-modified organisms and perhaps other industries' side-effects result in more and more common mutations, some breakthrough in DNA manipulation technology might (in sci-fi handwavium manner) result in a personal health maintenance device becoming widespread, with the original rationale being that people could use a device to mitigate these chaotic effects on their DNA. With more advanced handwavium, it might develop into a device that could also let people manipulate their DNA for positive effects rather than just halting damage. Back in realism-land, I think we're much more likely to mainly be causing all sorts of additional disasters with genetic manipulation before we get to that point. A more optimistic version might be that after acceptance that corporate GMO crop development was a disastrous mistake, a ban on releasing such organisms was instated and more prudent controls were put of GM research for 1000-10,000 years, until it was well-understood. At that point, a more enlightened society with much more scientific understanding, and much less extremist rogue megacorporate capitalism, allows personal devices where people can modify their own DNA and other biological factors in relatively safe and well-understood ways. [Answer] One reason that would immediately cause everyone to want one of these machines is if they were able to reduce aging effects. It would most likely need to go one step beyond DNA modification and be able to tamper with enzymes, telomeres, etc but by doing so it could well roll back your body clock or at least reduce the effects of aging. [Answer] Genetic manipulation devices for whole multi-celled organisms (as opposed to sex cells) are unlikely to ever develop, because you would have to change every single cell in the organism. That said, here are some uses they could be put to if made cheap and common: * Scientific research could be greatly advanced if you could change your test subjects to fit your experiment, instead of breeding through multiple generations * Cloning wouldn't be researched because you could simply change the organism/human after birth, so why bother? * Changing your own abilities would become possible to a greater degree, since you can change your genes * Perfect pets are a very likely use of such devices * Genetic sabotage might become a form of torture ("I've changed your DNA. Tell me what I want to know, or I'll let you slowly turn into a hamster!" ]
[Question] [ Would a civilization that is trying to permanently colonize a landless world with no atmosphere (think Europa's sea) be able to do so? Permanence matters - it means you can't simply build domes that contain atmosphere as they would not survive for millenia. You need a civilization for which aquatic life is naturally adapted. It's easy to imagine how a civilization would be able to adapt to sea-only world as far as adjusting the lifeforms to be aquatic (after all, most of Earth life is). But how could they preserve the technology over long term, if there's no possibility of fire? Without fire, you can not produce new metal (no smelting of ore). Are there plausible solutions to this? (within somewhat realistic realms of technology - e.g. no "unobtainium", magic, energy-state beings and such. Most likely path seems bioengineering or unusual yet plausible chemistry. [Answer] Actually, some of the challenges you describe might not be too hard to overcome. Maybe you've thought of the same things I have. Metals I'll tackle [smelting](http://en.wikipedia.org/wiki/Smelting) first. The key issue you described is that fire would be impossible to create. Well, there is a workaround. Smelting doesn't necessarily need fire; it simply needs heat. How can you produce heat? Well, there's the obvious idea of a portable heating device. All you need is a way to power it - solar might be good, although in a world with nothing but liquids, hydropower could work. Lets go with hydropower for now. To get the materials to find/produce metals, you have to dig. Given that there isn't any land, you have to go to the bottom of the ocean. I would recommend a permanent undersea base, at the bottom of the ocean. Hydropower could be possible if any currents can be harnessed, similar to [tidal power](http://en.wikipedia.org/wiki/Tidal_power). Miners can attempt to dig into the crust and extract ores, which can then be refined into metals and smelted, using heat, which is provided by a device powered by the currents of the ocean. Atmosphere This really isn't a big issue, especially as you've said that it doesn't really matter. First off, are the colonists suited for aquatic life - i.e. can they breathe underwater? If so, you can skip the rest of this section. If not, though, they need some sort of air. Now, it isn't feasible to simply keep on resupplying the colony with air - that would be cost-prohibitive. But what you can do is utilize an idea that has already been proposed for missions to Mars: bring plants, or plant-like equivalents. Humans breathe in oxygen and breathe out carbon dioxide. Plants do the opposite. In theory, if enough nutrients are continuously injected into a system, plants and humans could survive together indefinitely, each taking in the other's waste gases. By "plant-like equivalent," I mean an organism that performs that function for the colonizing species. Or, if you're lazy, perhaps advanced [carbon dioxide scrubbers](http://en.wikipedia.org/wiki/Carbon_dioxide_scrubber) would do. By the way, you can supply the plants with light by electric lamps. Power See "Metals". Hydropower and solar power would work well, although hydropower is preferable if you're at the bottom of the ocean smelting metals. [Geothermal](http://en.wikipedia.org/wiki/Geothermal_energy) is also an option, as is nuclear. The issue with the latter is getting fuel and subsequently disposing of it, so I'd stick to hydropower. Fossil fuels are also an obvious choice, but I'd stay away from them. Even if they formed on a planet like this, there of course would not be a never-ending supply of them. A few centuries in and the civilization would be stuck. Also, they would completely pollute the once-pristine planet. In response to [a comment from DVK](https://worldbuilding.stackexchange.com/questions/1082/would-a-civilization-that-is-trying-to-colonize-a-landless-world-be-able-to-do-s/1083#comment2192_1083): I'll defend the possibility of solar power because there is still a home star. There's nothing preventing the colonists from building a power-collection station on the ice. In fact, having ice means that buildings on the ice are possible, and many habitats would not have to be on the ocean floor. Food If you want a self-sustaining system here, you're going to need to bring in other organisms to eat. You'll need to create a food web here - perhaps an entire ecosystem. If the colonizers are vegans, you're set - just bring in plants. If they're more of the red meat variety, though, you're in trouble. Having cow-like creatures would be a waste of space. Try aquatic creatures - fish are, of course, the first thing that comes to mind. Special Case - Europa Let's say that the planet in question is [Europa](http://en.wikipedia.org/wiki/Europa_(moon)) (albeit a scaled-up version). This means there is a layer of thick ice surrounding the planet, which covers a thick ocean, possibly of water. This is, actually, pretty good. Why? Well, the ice can act as land. For all intents and purposes, what good does land do? It serves as a support structure. This means that buildings, towns - perhaps even cities, if the ice is thick enough - can be built on it. And, yes, stations for solar power. Having Europa as a planet to colonize actually gives us a little loophole, which could help the intrepid colonists. There are practical issues to consider, such as actually getting through the ice, but those can be solved. In Science Fiction The problem of how to survive on a planet with no land has been considered in [The Lost City of Faar](http://en.wikipedia.org/wiki/The_Lost_City_of_Faar), the second book in the Pendragon series, by DJ MacHale. The people of Faar have survived by building floating cities on the ocean. If there wasn't ice, this would be easy - just build a floating city and cover it with a dome. If there was ice, you would have to try and make the city a submarine. By the way, the Pendragon series itself could inspire a whole series of questions on Worldbuilding simply because of its premise, traveling through wormholes to different parallel universes in different times. But I digress. . . [Answer] I think the answer is yes but we have to examine why and how. ## The nature of the target First of all, we need to define what they're trying to colonize. Since [Europa](http://en.wikipedia.org/wiki/Europa_%28moon%29) is the only world where we can assume, based on current knowledge, that such conditions would exist, I'm going to assume they're trying to colonize a world very close to it or that resembles it almost completely. A few important things stand out - without an atmosphere, there's no chance of atmospheric breaking, but we also don't have to worry about overheating. If we go by Europa measurements, we're dealing with Moon-like conditions on the surface - temperatures at -150 to -170 Celsius[[1](http://en.wikipedia.org/wiki/Europa_%28moon%29)] on the surface and a gravity about .1g (Europa has about .134g[[1](http://en.wikipedia.org/wiki/Europa_%28moon%29)], but we'll assume .1g for simplicity). At the poles, the temperature might be down to -220, so it would be preferable to avoid them. It's also likely that, if there is any relationship between surface temperature and ice layer thickness, it'll be thinner farther from the poles, so again we're aiming for the equator. Overall, it would be preferable to avoid having to work on the surface - it'll be cheaper on the equipment and more efficient. The ice layer is assumed to be about 30km deep on Europa[[1](http://en.wikipedia.org/wiki/Europa_%28moon%29)] (although there's competing assumptions, this seems to be general consensus) which is damn thick. This means any ship can't just crash through or bomb the surface to get straight to the ocean. Even if that were possible, the water would evaporate explosively[[2](http://zidbits.com/2011/05/why-does-water-boil-in-the-vacuum-of-space/)] (it would just boil instantly) - this may or may not be to the benefit of a lander that wants to reach the ocean, but it would be best to avoid it. Any effort will have to deal with the pressure difference eventually however. ## The undersea world The ocean itself shouldn't have a pressure too high for life or structures. This is because, even though Europa's oceans are presumed to be 100km deep[[1](http://en.wikipedia.org/wiki/Europa_%28moon%29)] (10 times the maximum depth of ours, or 25 times the average), the gravity is about a tenth as strong, so it balances out to an uncomfortable but manageable 1030-1050 bars (bars are a bit less than an atmosphere in pressure). This is about the same as Earth's deep ocean floor[[3](http://en.wikipedia.org/wiki/Deep_sea_creature)], where there is vertebrate life so we know it's swimmable and survivable, albeit not unaided or without adaptations. This assumes a water density similar to that of ocean water on Earth - unless we're going to debate the possibility of non-earth-like life, we'd best stick with this estimate since we at least have a real example of it. Underwater, there should be practically no light - so we're dealing with the same conditions deep ocean life has to deal with. An important difference from our oceans is that life would probably be denser at the floor rather than the "surface". This is because, since there's no sunlight or contact with the outside, all the nutrients will have to come from hydrothermal vents, underwater volcanism etc. . We need to count on these vents because they're going to be our best chance for power in this ocean. So, if they don't exist, there's probably very little life (so no food) and very few ways to generate power. ## Comparing with Earth sizes The surface area of Europa is approximately the same as Africa's[[4](http://en.wikipedia.org/wiki/Africa)]. Assuming the ocean is uniformly distributed and we don't have serious elevation differences, the surface area of the sea floor is the same, if everything south of Angola was gone. That should be plenty for a few hundred million people - Africa has a bit over a billion and it isn't that densely populated either (going by average density here). ## Packing food and provisions We also need to know what to take with us. Old estimates on how large a colony has to be where as low as a couple hundred people. However, newer estimates in 2013 place the number in the range of 15-45 thousand[[5](http://en.wikipedia.org/wiki/Generation_ship)]- these estimates take illness, accidents etc. into account, which is what we need. Since we're prudent, lets assume we send about 2 times that many. That brings us to a minimum of 80 thousand individuals. To estimate basic habitation and food needs for all these, we can take our cues from the ISS[[6](http://www.nasa.gov/mission_pages/station/main/onthestation/facts_and_figures.html#.VDLfAf1RUaI)][[7](http://en.wikipedia.org/wiki/International_Space_Station)][[8](http://en.wikipedia.org/wiki/Life_support_system)] - extrapolating from their numbers (5kg food and water per day, per individual), we can conclude we need about 72e3 metric tonnes of food for a year, 142e3 if we're packing 80e3 people - lets round that up to 80e3 for convenience (thats 80 kilotons of food, 160 if we're sending 80 thousand colonists). That includes 70% water as well, which we'll normally be getting through refinement of oceanic water, but lets say we're really prudent and want to pack extra food or something. Just for kicks, the amount of food for 80 thousand without the water would be 21 kilotons. Assuming 40e3 individuals surviving and a population growth of 1% (a bit less than Earth's I think) it would take 325 years to reach a million people and 560 years to exceed 10 million[[9](http://www.metamorphosisalpha.com/ias/population.php)] (if all 80e3 survive, those numbers are 260 and 490 years respectively). Considering the amount of food we have to pack for a single year, if there isn't a sustainable habitat by the end of the first year, it's pretty much over, unless enough people die off to make the resources adequate for those that remain. We'll have to assume there's enough. ## Only mutants can live in this world So far it seems like it could be done. But what kind of adaptations would it require from individuals to be comfortable? Judging from how deep sea vertebrates have adapted, there's a few points that have to be made. Firstly, there is going to be very little to no light - any creature would have to depend on other senses, sound being the best candidate. Also, the pressures require some softness - ocean-bottom life generally has few bones and more cartilage[[3](http://en.wikipedia.org/wiki/Deep_sea_creature)]. There is of course the issue of breathing - deep sea life has to deal with hypoxic conditions[[3](http://en.wikipedia.org/wiki/Deep_sea_creature)], but we have to assume there's enough oxygen to go around so we can have plenty of life, otherwise it's a dead end anyway, so we'll skip adapting to hypoxia and just consider breathing in water. Swimming adaptations would also be very beneficial. Considering the above, I think that if this civilization's bioengineering is good enough, perhaps extra cartilage or turning most bones into cartilage would be an important step. I'd prefer extra cartilage, due to the fact that I'd rather not have a change that would give up the advantages of standing. This will probably be most useful on and around existing bones, so yeah we got fore-head ridges and all sorts of protrusions (but of course, I'm no biologist). For breathing, unless we are ok with having to gulp water to breathe, a preferable solution would be gulpers on the side of the jaw, like large slits on the cheeks (possibly quite long, from ear to chin to allow for a good volume of water), which instinctively work and close up (like sphincters) when outside water to prevent stuff from falling in. The gills need to be connected to these so they'd either be on the sides of the neck or the sides of the torso, since we want them to be close to both the gulpers and the heart. The torso is inconvenient and dangerous, so I'll go with the sides of the neck. They should be on the sides since they'll be shooting water out and that's preferable to placing them on the back, which can be problematic as well - the neck is easier to protect. Since sound will be a lot more useful, some form of echolocation would be needed. The preferable way, in my opinion, would be to extend the ears so that their cartilage occupies a larger area on the head (yeah I know :P). A clicking mechanism is also required - it can be done with the mouth, which would be practical in some ways, but it might be better to have a separate organ for it. Lets just keep the mouth for now, which can create complex sounds already which might be useful. Finally, since sound will be important but it's likely vision is the most well-developed sense (and can pack information more efficiently), it might be a good idea to link the center for hearing and vision in the brain, a sort of engineered synesthesia[[10](http://en.wikipedia.org/wiki/Synesthesia)], to empower it. ![what the ears might look like](https://img1.wikia.nocookie.net/__cb20130413054333/startrek/images/c/cd/Eris.jpg) "Seriously, forhead bumps?" A Vorta from Star Trek - this is what adapted ears might look like, sans the hair of course - that wouldn't help. Swimming adaptations are problematic because webbing gets in the way and is the most obvious approach, short of giving up legs. Webbing in hands will reduce dexterity since now you can't pass anything between your fingers. Webbing amongst toes wouldn't be as much of an obstruction, but webbing between fingers can only do so much. Placing it between limbs can also be problematic. If you have large flaps on the side of your torso, you can't carry anything under-arm anymore and it can get in the way of so many activities (one might argue that if it's elastic or long enough it wouldn't be a problem, but the more elastic and flappy it is, the less help it is when swimming). Perhaps the only way would be to have webbing between the legs, which would give everyone a permanent skirt. Besides changing how clothing works, it might not be that much of a problem - most of the time would be spent swimming and if someone wanted to run, perhaps an adrenaline-triggered mechanism could be implanted, where, depending on whether the gills are working or not, the webbing between the legs tightens or relaxes. I don't really like this either though since sex would be a problem and it's inelegant. Maybe we'd have to settle for webbed (and probably longer) feet, to the extent that they don't cause problems with walking. ## No smooth landings for us The issue remains on how to get there, land, submerge and establish a habitat. I have one proposal that may be plausible enough for fiction. The ships wouldn't land as much as impact the planet's surface. I'm thinking of something like a geodesic sphere or buckyball: [![enter image description here](https://i.stack.imgur.com/fYsDJ.jpg)](https://i.stack.imgur.com/fYsDJ.jpg) [![image of another sphere](https://i.stack.imgur.com/dR7Jl.jpg)](https://i.stack.imgur.com/dR7Jl.jpg) (source: [amazonaws.com](https://neutrinodata.s3.amazonaws.com/theage-education/cmsimages/web/89d4eabc-8416-11e0-98bd-005056b06a0e-3187509.jpg)) The reason I'm thinking of an impactor is because trying to land softly requires propulsion, which adds mass and complexity - also, you're not going to use it again ever so it seems impractical to pack it. If a steep enough trajectory can be accomplished, the impact can be softer. Although bouncing and achieving escape velocity isn't very likely, what might be likely is that the impactor bounces and places itself into orbit, which would be bad because it might take years for it to make contact again, at which point it might bounce again ad nauseam. So, to prevent this, along with an appropriate angle, the impactor should have spikes in all directions on the surface, deployable and retractable. As it makes contact with the surface, it can dig into the ice much like a tire using spikes or a boot. It will no-doubt roll, but that's tolerable. ![image of spiked ball](https://2.bp.blogspot.com/-yfrLJTbWTl8/Ty_N1liwIJI/AAAAAAAAB4Q/av7AQ-l3cTQ/s1600/camera+022.jpg) ![image of spiky sphere](https://cdn.instructables.com/F34/ER3V/FWBNLGFZ/F34ER3VFWBNLGFZ.LARGE.jpg) To provide more control, we can separate the outer frame from the inner shell, which is our actual ship. The inner ship can rotate independently, allowing us to use gyroscopes and its rotation to cause the ball to roll in any direction. It could help the ship get out of a crater or spiky terrain and reach a flat surface. Europa's surface is relatively smooth, with "relatively" being the key-word - it is presumed that jagged kilometer-high ice shards exist on the surface. ## Descent To descend through the ice, the outer shell can heat itself up - I think about 600-1000 degrees Kelvin should work (about 300-700 degrees Celsius). The ice will probably just evaporate at this point, along with non-rocky impurities (metals will also evaporate[[17](http://www.newton.dep.anl.gov/askasci/mats05/mats05256.htm)]). The heating should cause the ice to break or recede slowly, hopefully turning into water or some composite liquid underneath the ball if it is sealing the hole sufficiently - otherwise it will be evaporating all around the ball. Spikes should be retracted during all this to allow descent. There is a huge danger to be careful about when the ball reaches the ocean - at vacuum pressures, assuming the ocean has anything near our own ocean's density, it will evaporate violently. This can be a problem since it may be a powerful enough push to prevent descent into the ocean or shoot our ship back into orbit or farther. Even if it just keeps it there, it'll be insurmountable. To prevent this, we need to equalize pressure - I think a good way would be collapsing the ice from the sides of the tunnel during descent to have it clog the hole behind the craft. This is why it might have to descend at an angle. Heating can be focused in the direction of intended travel and small charges placed on the top-side of the tunnel to be blown after the ball has rolled deep enough. This way, the pressure differential should last much less time and hopefully be reduced to the point where the evaporation doesn't prevent sinking into the ocean. Once the craft splashes in, it will take a long time to descend. It could be months (good thing we packed food!). This and previous stages, is why I think hibernation would be necessary, if not unavoidable. The impact and descent process can be handled automatically and space travel will probably take a long time anyway. This way, accidents can also be prevented - you don't want some guy who refused to strap themselves in for impact getting splattered and their pieces floating around during the whole process. If colonists aren't bio-engineered beforehand, the hibernation period might be a good chance to do that (to them :P) although I think doing it before launch would be much safer (obviously). If the colonists aren't hibernating during impact, put on some AC/DC, they'll need it. ## After submersion During descent, thermal emissions can be scanned for and targeted using gyroscopic turns to slowly move above them. The strongest should be the vents. The ball can also (and should) right itself at this point. The reason is convenience - if we separate the top and bottom halves of the sphere to habitat and power generation, the bottom half should land over or near a vent to harvest power off it while the habitat stays over it. For safety, it could also detach while staying tethered to the base through cables and ascend a few kilometers to avoid the possibly dense wildlife (and conditions) at the ocean floor. Since fish like to take bites out of power lines and there's other environmental dangers to consider, the cables should be heavily reinforced. They should also serve as ladders for colonists who need to descend to the power plant for repairs, maintenance or scouting. Of course, this is if they see a reason to make the halves detachable. At the floor, around the vents, it should have enough sea life (including bacteria that feed off the vents and seem to be the equivalent of plants for deep ocean life) to eat and possibly farm as well. The habitat can soon be extended once mining and construction equipment is deployed, but there should be a few months time before that's necessary. The landing spikes can help protect it from larger creatures, should they exist. Smaller ones probably won't be able to cause any serious damage. edit - I've made an extremely primitive sketch of how it would work - it's quite terrible since sketchtoy caps out my cpu and the mouse behave erratically, but it might be better than nothing: [http://sketchtoy.com/63258025](http://sketchtoy.com/63258025_) [Answer] HDE gave a very good answer but I'll take up one point he missed: Permanence. The lack of total permanence of structures isn't a reason you couldn't colonize. 1) Ever hear of repairs? 2) Even if you can't repair the domes for some reason that doesn't mean you can't build new ones as the old ones wear out. ]
[Question] [ The overview: Would any form of complex life be possible near absolute 0? At least for my personal standards, the "life" merely has to be: * a self-sustaining, * self-replicating machine, * with a "computer" / brain, * that doesn't necessarily need to be cellular. The goals: To optimize my search I have 2 tier-lists of goals based on what turns out to be realistically possible for both "mechanism" and "temperature", with the bare minimum for "mechanism" being artificially replicated metallic robots, and the highest tier being a possibly cellular, organic lifeform that automatically reproduces, heals, grows, and thinks sapiently. While the tier-list for "temperature" would preferably be as close to absolute 0 as realistically possible with reality's exact unaltered laws, and at least as cold as any possible complex computer can exist at, even if artificially constructed. The solvent, if any: My first thought was for the beings to be very similar to robots, taking advantage of the almost non-existent temperatures for a brain comprised of a quantum computer, but then I realized these beings would probably have to be built manually, which is acceptable, but is of lower priority than a cellular and self-constructing design, if that turns out to be realistically possible. I then studied the basic mechanisms of cellular life and came to the possibly eroneous conclusion that complex cellular life would require a solvent to transport various resources, yet apparently only helium remains liquid at near absolute 0. This led me to studying for literally multiple hours, trying to find any information on the material solubility of liquid helium, on which I found almost nothing üòÖ aside from the vague statement that "helium is a noble element and reacts with very little." The energy / food source(s): As for energy, my current best idea is for the lifeforms to derive energy from some sort of nuclear reaction, as both solids and 'apparently' radiation can easily exist near absolute 0, and the best specific reaction I've found so far would be the reaction of "free radicals" oxidizing pyrite into "sulfate" (whatever that is) and apparently iron oxide, although from what I've read, the iron oxide couldn't be used to build material or "flesh", so sadly it may be largely wasted as excrement. The current ideas: This brings me to my current best 2 ideas for possible complex life at absolute 0: * At best? A cellular creature that somehow has access to and swallows radioactive uranium, pyrite, and possibly some form of construction material based in carbon like calcium or proteins, deriving energy from the radiation/pyrite-derived sulfate, and repairing and growing tissue with the carbon or silicon or "whatever". If possible, it circulates liquid helium through its body to transport nutrients, and either simply never excretes this helium, or drinks helium from natural reserves in its environment. It would move around either by rolling using its spherical form occasionally pushed by two thick trunk-like arms, each with minimal surface contact with the icy ground, or by walking on two legs optimized for minimal surface contact with the icy ground. * At medium: a similar self-replicating cellular lifeform at some higher temperature, whatever turns out to be the lowest possible temperature to harbor complex self-replicating life. * At worst: simply an artificial robot with a quantum computer "brain", living off of nuclear reactions. [Answer] Purely electromagnetic. For all practical purposes chemistry does not happen at 0. But electromagnetism definitely happens. <https://en.wikipedia.org/wiki/Persistent_current> > > In superconductors, charge can flow without any resistance. It is > possible to make pieces of superconductor with a large built-in > persistent current, either by creating the superconducting state > (cooling the material) while charge is flowing through it, or by > changing the magnetic field around the superconductor after creating > the superconducting state.[1] This principle is used in > superconducting electromagnets to generate sustained high magnetic > fields that only require a small amount of power to maintain... > > > Your creatures are comprised solely of persistent current cells flowing in their superconducting substrate. Growth and reproduction of these creatures takes place via electromagnetic manipulation of the molecules of the substrate, rearranging them in patterns favorable for growth and development of these electrical creatures. Of course such creatures would feed on electricity, arranging for naturally occurring charge differences to be added to their own perpetual current loop. I can imagine a "field" of such creatures, their substrate having been arranged and rearranged with the generations into overlapping geometric crystalline patterns. Charge harvesting spicules protrude into the overlying vacuum to collect charge. Perhaps periodic storms bring dust or debris allowing the electrical creatures to conduct up and out of their substrate, and establish colonies elsewhere on their world. Shout out to the classic scifi [A pail of air](https://www.gutenberg.org/files/51461/51461-h/51461-h.htm) and its memorable portrayal of a frozen earth. > > He wasn't just making up those ideas. Odd things happen in a world > that's about as cold as can be, and just when you think matter would > be frozen dead, it takes on a strange new life. A slimy stuff comes > crawling toward the Nest, just like an animal snuffing for heat‚Äîthat's > the liquid helium. And once, when I was little, a bolt of > lightning‚Äînot even Pa could figure where it came from‚Äîhit the nearby > steeple and crawled up and down it for weeks, until the glow finally > died. > > > ]
[Question] [ In a universe I am creating, there are many living species of humans (mammals from the Homo genus) (for example, there are ogres, giants, merfolk, halflings, dwarfs, and goblins). One of them is called gnomes (their scientific name is Homo minimus) (that means "tiny human"). Their basic characteristics include: 1. Adults are as small as a domestic cat; 2. They are as social as meerkats; 3. They have an improved sense of smell, and an improved sense of eyesight, but a worse sense of hearing; 4. They are omnivores with herbivorous tendencies like gorillas; 5. They have a higher risk of osteoporosis, and senile dementia, and a lower risk of type 2 diabetes, noninfectious cancer, and noninfectious cardiovascular disease; 6. Males are larger than females (mandrill-like sexual dimorphism); 7. They are MUCH more likely to be rhesus negative than anatomically modern humans (62 % of gnomes are rhesus negative) (I do not mean rhesus null, I mean at least the simple absence of D antigen), and they are also more likely than anatomically modern humans to have blood type O (70 % of gnomes are blood type O, 14 % are type A, 14 % are type B, and 2 % are type AB) (to be exact, 45.6 % of gnomes are O rhesus negative, 7.3 % are A rhesus negative, 7.3 % are B rhesus negative, 1.8 % are AB rhesus negative, 24.4 % are O rhesus positive, 6.7 % are A rhesus positive, 6.7 % are B rhesus positive and 0.2 % are AB rhesus positive); 8. They have an average lifespan of 9.5 decades (95 years old), the world record is 14 decades (140 years old); 9. They are more fertile than anatomically modern humans (the twin birth rate for gnomes is 13 to 22 twin sets per 1,000 births) (the twin birth rate for anatomically modern humans is 9 to 16 twin sets per 1,000 births); 10. They can interbreed with anatomically modern humans, but it rarely happens, because if a female gnome reproduces with a male anatomically modern human, giving birth can be a nightmare EVEN by human standards (this is comparable to a puppy that has a Scottish terrier as a mother, and an Irish wolfhound as a father) (nevertheless, the resulting offspring between a gnome and an anatomically modern human is often fertile, except that female hybrids are more likely to get PCOS, and male hybrids are more likely to get oligospermia). [Answer] Insular dwarfism See [wikipedia](https://en.m.wikipedia.org/wiki/Insular_dwarfism) TL;DR: > > Insular dwarfism, a form of phyletic dwarfism,[1] is the process and condition of large animals evolving or having a reduced body size[a] when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf breeds, called dwarfing. This process has occurred many times throughout evolutionary history, with examples including dinosaurs, like Europasaurus and Magyarosaurus dacus, and modern animals such as elephants and their relatives. This process, and other "island genetics" artifacts, can occur not only on islands, but also in other situations where an ecosystem is isolated from external resources and breeding. This can include caves, desert oases, isolated valleys and isolated mountains ("sky islands").[citation needed] Insular dwarfism is one aspect of the more general "island effect" or "Foster's rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bodies (island gigantism), and large species tend to evolve smaller bodies. This is itself one aspect of island syndrome, which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts. > > > [Answer] ## Underground nutrients Your future gnomes dispersed onto a small continent with a highly porous karst topography, full of caverns and hidden water sources. The surface is poor in rivers, high in elevation. The trees that grow there would be small and stunted, save for one remarkable species whose taproots can navigate small deep cavernous passages and pierce dozens of meters of solid limestone. These trees have full access to deep reserves of fresh water, and the nutrients that can be found there. Growing to immense size, spreading by stolons across the landscape, they diversified into a highly successful genus. In this process, the trees compete with one another, but not so much that they prevent one another from seeing to one of their basic ecological necessities: they need fixed nitrogen. Nearly all the trees pump excess glucose and fructose down their taproots into the caverns, where they nurture symbiotic bacteria acting in a loose association comparable to the root nodule of a legume. However, these bacteria have not evolved into a tight physical association with the trees as of yet, and the underground ecosystem is far more open-ended. There are many puddles of sugary water laden with bacteria and yeasts, fed by the tree roots so long as they contain sufficient fixed nitrate. The dead taproots decay into hollow tubes that ensure a vigorous air circulation that brings in fresh nitrogen to fix, and also permits the habitation of some organisms. The gnomes are small due to the need to traverse small passageways as well as "insular" dwarfism within individual cave systems. Just so, we see the colonization of the underground landscape not just with bats and the rich fertilizer they produce, but also with humans that evolve to become small and capable of seeing by what to us is the dim light of autofluorescent bacteria. They feast occasionally on bats, but more often consume bits of the sugar and alcohol-rich nectar the trees leave behind, being careful not to destroy the resources that sustain them. They are unfortunately prone to osteoporosis because although they receive an endless supply of calcium from the limestone, they have very low intake of phosphate. In the end their feces and their corpses return their nutrients to the ever-circling roots around them. But perhaps their greatest contribution is in their mining - scraping new passages into the stone that improve the carrying capacity of their environment for untold years to come. [Answer] # Evolutionary Pressures are not science-based (One thing you ask for evolution to cause is better eyesight. [That was answered here](https://worldbuilding.stackexchange.com/questions/224193/what-changes-might-happen-if-a-group-of-people-began-living-in-a-cave-full-time/224198#224198). Evolution works this way for everything else you ask.) The tags “Evolution,” “Biology,” and “Science-based” can’t be applied to this problem because evolution does not lead to anything; it has no goal and no “survival instinct.” In other words, DNA doesn’t have a brain. What this question asks for is Lamarckian inheritance. That can’t have the science-based tag, an evolution tag, or a biology tag. None is the science-based answer. But to help your story-based problem of having naturally occurring dwarves as a species (which of the 23 science-based definitions of that you are using here is not stated), the problem seems to have already been partially solved in the real world by deleterious and disadvantageous genetic mutations. ## Chandra Bahadur Dangi was born in Nepal, grew to a height of 54.6 cm in height (the average cat is 46 cm—a comparison asked for in this problem) and lived to a ripe old age of 75 years. ![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Chandra_04.jpg/800px-Chandra_04.jpg) The medical condition causing Chandra's size has never been determined, but obviously some condition does exists which can do it. ## Speciation of Chandra's dwarfism It is impossible to say if Chandra's condition could at some point become a new species without diagnosing the condition. His woman counterpart however, Jyoti Kisange Amge, was diagnosed with one of the 5 known types of primordial (genetic) dwarfism, which would be the only ways a new genetic species could arise; which are: * Achondroplasia (Frequency = 1/40,000; hereditary 20%) * Taybi-Linder syndrome ( * Majewski osteodysplastic primordial dwarfism type II (Frequency = rare; heritibility: autosomal recessive pattern requires both parents to carry the gene - a normal human donor would dominate the condition) * Seckel syndrome (Frequency = 1/10,000; hereditability: autosomal recessive pattern requires both parents to carry the gene - a normal human donor would likely dominate the condition) * Russell-Silver syndrome (Frequency = estimates of 1/30,000~1/100,000; heritability: the problem arises from improper methylation. It has been identified as an autosomal recessive pattern however, rarely, Russell-Silver syndrome can run in families. In some affected families, the condition appears to have an autosomal dominant pattern of inheritance (but not confirmed). This would mean that one single donor parent may cause the condition in the children. No evolutionary pressure can cause any condition to happen, however, as mutations are a stochastic process, the probability of a dominant form of dwarfism surviving can be affected through the evolutionary pressure of a reduced gene pool. Diversity will likely prevent primordial genetic conditions from gaining a foothold in a population because normal, healthy humans have rigorous DNA repair mechanisms which can correct these mutations in later generations, and wipe out the mutations which created your "species." Thus the process of creating a dwarf species is four-fold: 1. Reduce the gene pool to a single clade or family to promote genetic diseases. 2. Wait several generations for deleterious recessive mutations to manifest, and by chance, several with your desired characteristics may or may not occur 3. Provide advanced medical and security support to protect the disadvantaged population from predation, tribal war, disease, and any other natural inhibition to procreation 4. Remove people without the desired traits from the gene pool, as their children can correct the recessive deficits. (You don't have to kill them, just exile them as outcasts and prevent cross-breeding) [Answer] You can merge two of the answers to get a somewhat good answer... Lets say their ancestors were normal people from a society that lived in the surface. They used to outcast or abandon their deffective offspring (I think spartans used to do so, throwing them from a cliff). So, babies with dwarfism would be left out and the few that survived ended up forming a little society in the caves where big people could not follow and kill them. Their normal children would be left in the surface, die suffocated in the tunnels as they grow, or be sacrificed, as you like. The point is that the "big people" genes would be slowly removed from the gene pool until only the ones with dwarfism were left. Then something happend to the big people and left the small people, lets say they were decimated by orcs or something. The species could have then evolved privileging smaller individuals that could navigate further in the tunnels, slowly becoming your current gnomes. I can think a lot of wrong thing with this... For example, a stable society living in a fixed place would most likely be farmers, so not so far in time to let a new species evolve from them. Another option, you can say you have a peacefull society with a tendency to dwarfism, so its normal. Then a new species appears and hunts your humans (lets say orcs again) and the only ones having a chance of survival are the ones that can fit into the tunnels and hide/live there. As before, normal humans would not survive outside because of orcs nor inside because of their size, effectively letting live only the smaller individuals. The most difficult part sould be having a big enough dwarf population in the tunnels to start with... [Answer] The discovery of the aplinium tree forever changed human society. The aplinium fruit was a potent aphrodisiac that guaranteed the greatest pleasure and fertility. Wild trees that grew in harsh forests resisted every form of domestication; the fruit of such trees blossomed once per season and only for a few hours, as the fruits were also favored by the local wildlife. Only the tallest humans could harvest them, and harvesting meant proliferation. The shortest humans were quickly rejected from society as being unfavorable mates. Often expelled from local communities, these humans formed their own colonies in the dense forests, determined to develop their own means for harvesting the coveted fruit. Without access to forges and tools, these humans evolved to use the bounty of the forest for their survival. Over generations they become shorter, as the taller of them were scorned for being like the others - the foresakers of the kin. The shorter humans soon discovered that the roots of the aplinium trees were rich in the same active chemicals of the fruits, and developed various means for extracting these chemicals without harming the trees. Shallow underground caverns wound gently around the roots of the trees, tapping the sap of the tree at various locations under the earth. Shallow tunnels led to deep and vast complexes, providing shelter and communal space for the society hidden away from the predators above. With the the aid of the aplinium sap, gnomekind was borne, with little regard for those who banished them. [Answer] # You don't want evolutionary pressures that lead to gnomes For some reason, I think a lot of people think evolution works like this: 1. The environment changes 2. Organisms adapt 3. Now the organisms are fit to the environment But that's very wrong. As in [this answer](https://worldbuilding.stackexchange.com/a/224680/76070), the idea of evolution having a goal is wrong. Evolution is not about survival of the fittest or creating better organisms. Instead, organisms that are fit enough survive and those that are not fit enough do not. How evolution (in general works) is more like this: 1. Organisms become more genetically diverse through random changes 2. The environment changes 3. Organisms that are not fit enough die off or don't reproduce #3 is a problem if you still have humans in your world; if humans die off and gnomes survive THEN that's evolution, but if humans and gnomes co-exist that's not evolutionary pressure, that's just random variation. Having a group of more gnome-like people separate from humans at some point in the past should be enough to make them genetically distinct. The rest of your requirements (blood type, etc.) could easily just happen by random chance. So to have gnomes, the only real requirements are: * random genetic variation * gnomes can survive and reproduce ]
[Question] [ With metals you can take something you don't like, melt it down and use the metal for something else. My question is, can the same be done with porcelain? In my fantasy world, metals like gold, silver, copper, iron etc. are all scarce except in one very specific place in the world, so most people get by using bone china made from the skeletons of dragons and other monsters whose biology incorporates a lot of naturally occurring biometals. Because of the strength of the bones, the china made from them is much more durable than real life ceramics, and can be used to make weapons, armor, and even building materials. This on top of porcelain's many IRL uses makes monster bone china the primary "universal currency" most countries use to facilitate trade with peoples outside their borders. Of course making "money" like coins, chips, or things of a similar nature out of this porcelain only makes sense if the porcelain can then be processed or reforged into a more useful shape, since its value is derived from its utility. If you can't use it for anything after it's been made into a coin, then you'd be better off trading in powdered or unprocessed bone. So can you reuse porcelain or china once you've already made it into the shape of a coin, a plate or a tea set? [Answer] What is needed for currency: There's a finite amount at any given time. There isn't too much or too little of it. If the elements of bone come from specific types monsters/dragons which changes the quality of the bone china in a way that's different from standard bone, this adds a layer of rarity that you might not get simply from bone china taking skills and a forge to make. It doesn't rot or wear out. Best if it CAN get wet without being destroyed. Portable, lightweight. Difficult to cheapen, thin, or counterfeit. Bone china allows [light to pass through it and has a certain "ring" when pinged](https://www.thespruce.com/verify-bone-china-1908319). With an addition of dragon bone, it might sparkle a certain way or somesuch. There is a difference between bone china and porcelain--and though you are calling this porcelain in your question, you are actually asking about bone china. If counterfeiting is in question you might want to look into how antique dealers tell the difference--porcelain is a brighter white, light plays on it differently, the sound is different. Any savvy merchant will be looking for these differences. Possibly fungible. That is, the value of the currency does not depend on weight or measurement. You might have different denominations or sizes, but they tend to be static enough that they don't have to be measured to know the value. Not true in the case of salt or tea, but as it was used more often, things like that would be compressed into bricks that are of uniform size and shape so that one doesn't have to have equipment to know the value of the money. So basically, you can forge pieces of bone china where the value depends on size and what's in it. You can mix colors in even to differentiate, which would be more interesting than just size. It doesn't actually need to have ANY other use, even if that is a neat feature. Which is what you seem to be worried about. Take [cowrie shells](https://en.wikipedia.org/wiki/Shell_money) for instance. Because the answer to your actual question is not really. Not if they are glazed in any way. If unglazed maybe, but the energy needed would be more than just forging from scratch. This element of being able to reforge it is not actually needed. It will be worth more as currency than it likely will be in objects for the most part. Porcelain isn't metal, and that's possibly what will make it more valued, not less, if it takes skill to make and specific ingredients. You say: > > Of course making "money" like coins, chips, or things of a similar nature out of this porcelain only makes sense if the porcelain can then be processed or reforged into a more useful shape, since its value is derived from its utility. > > > But when things such as [pressed tea](http://jayshreetea.in/blog/history-of-tea-currency/), salt, and other utilitarian objects were made into money, and once they were, rarely saw service as actual tea or salt, as they were more valuable and more tradable in a recognizably monetary form. (Were phased out because the amounts needed were far too heavy). The same was true of [dagger](https://en.wikipedia.org/wiki/Knife_money) currency. While they were technically metal, they weren't actually used as knives, however utilitarian knives are. You can have bone daggers and things made of bone porcelain, but the currency just needs to be recognizable, and have the characteristics of a good currency. Now there is a fantasy model which does work like this--in the Dragonlance series, coin was Steel. And so were weapons. Here's [a message board](http://www.enworld.org/forum/showthread.php?355840-Dragonlance-steel-currency-and-gold-pieces) talking about the value of that vs. gold in the series and the RPG. [Answer] ## Porcelain can't be reforged and even if it could, it's ill-suited for use as a currency in your world. ## Why gold is a good currency [LiveScience](https://www.livescience.com/32863-gold-best-element-money.html) has an excellent discussion about why gold makes an excellent candidate for currency. They have four selection criteria: * Not radioactive * Not a gas * Won't corrode or react * Hard to find but not too hard This leaves a very short list of elements: rhodium, palladium, platinum, silver and gold. Every one of those elements should be extremely familiar to anyone who has purchased jewelry. It also helps that all these elements are pretty. ## Composition of Bone China [Bone china](https://en.wikipedia.org/wiki/Bone_china) on Earth is made from various quantities of aluminum, potassium, calcium and sodium with oxygen and hydrogen mixed in for good measure. Also, these elements are exceptionally common on earth and with the exception of aluminum, make up significant percentages of the human body. ## Too Common to be a Currency Unless this monster bone china contains one of the above listed currency-worthy elements, it's probably not going to be a good currency. Also, none of the currency elements make good candidates for inclusion in bone structures, where strength is required. Without "enrichment", the real life equivalent to this monster bone china would be using common red bricks as currency. Sure, it can be done but it doesn't make sense. Part of the point of a good currency is that it can't be used for anything else or is not quickly made to serve another purpose. Consider the alternative where currency is useful for many other uses. What happens when an object, say armor, is the most useful/valuable form for this monster bone china to take than small coins? The small coins will disappear because armorers will take in all the small coins they can to make the more valuable armor. ## (Not)-Reforging China Since china or ceramics in general are special forms of glass, reworking the china is done the exact same way; by essentially melting down the glass and recasting it. If you still want to go the reforging route, the biscuit temperature (not the final firing temperature) for bone china is [1200 to 1300 C](http://www.thepotteries.org/types/bonechina.htm). Low carbon steel reaches [reforging temperatures](https://www.azom.com/article.aspx?ArticleID=6115#10) at about 900 C. Even with a maleable clay to work with, what tools would you use to perform the reforging? You'd need a set of special ultra-high temperature tools to rework the porcelain while it's still hot. At these temperatures, you're not reforging porcelain, you're recasting it. ## Additional Reading [Ignition of Metals in Oxygen](http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0482073) [Answer] In principle, unglazed porcelain can be recycled. The material must be thermally stressed, then ground into fine powder which can be used to produce new material. However, any colored glaze will interfere with the final color of such recycled material, and virtually all porcelain has such a glaze. [Answer] Porcelain can melt. When it is fired, it is vitrified (turned into a glass-like substance). In theory, you could heat it up and melt it again. Then, you could pour the melted porcelain into a mold. You might also be able to grind the porcelain down and reuse it as mentioned in another answer. That doesn't mean what you've created would have the same properties such as the same strength. Even re-forging something easy like Iron takes special techniques to make sure that the Carbon content is kept low. However, you aren't asking about normal porcelain. You specified that the strength of the material is more durable than normal porcelain. The only way this can be achieved is if it ISN'T porcelain but something else. Materials have properties based on the elements, arrangement of atoms, and bonds inside those materials. Materials don't inherently "remember" how strong they were before they were incorporated into their new form, particularly when they are transformed into a glass-like end product like porcelain. Items that can't be reforged can be used as currency. Bitcoin, for instance, doesn't even have a physical form. It is a currency. The only true limit to using a currency is whether others will accept it. Examples of ancient currency include salt, pelts, and one tribe that carved massive limestone blocks. The limestone blocks never moved despite changing ownership. When one was lost at sea, it didn't even matter to its value. <http://listverse.com/2013/06/21/10-strange-forms-of-ancient-currency-2/> [Answer] I like your idea. You could certainly use unfired bone as currency (probably easier than using porcelain) Some thoughts... Is this dragonbone rare enough to be good for currency? Presumably new finds of bone keep getting made. You'll have to decide whether new finds get made often enough to cause inflation issues. Doesn't preclude using it; all economies have problems. I would suggest you dial back on the construction uses of dragonbone. This (as others have said) implies it is more common. Maybe it's used for critical fortifications only or in very wealthy people's McMansions of the Clan McMansion. It would be awkward to use the bones as currency, as they are not standardized, and it would be hard to make change. "Hey, can you break a vertebra?" Might be better to use the powder. You'd get a secondary industry making little containers for it, and a whole host of plotworthy counterfeiting schemes. ;D ]
[Question] [ In the movie Interstellar, they go to a planet where time flows by much slower for them while on it because of the increased gravity that planet is experiencing due to the nearby black hole. My question is whether or not something much smaller, like an asteroid or a dwarf planet even, could pass by Earth close enough to slow down time from our perspective? Is there something that could do the opposite and speed it up, and effectively slow everything else down? [Answer] Time wouldn't slow down from our perspective. The time dilation would be evident only if we were to check our clocks against a clock that's far enough from the celestial object (just as shown in interstellar) and/or after the celestial object is gone. That being said, since it's a function of mass, a sufficiently massive asteroid could cause dilation significant enough to be observable from one side of the planet to the other. But if the asteroid is too massive (because a millionth of a second off here and there won't make an interesting plot point), there might be many other inconvenient (and potentially devastating) effects of such a massive object passing by. How a small asteroid/planet is able to be contain so much mass would probably require a super dense fictional substance. Alternatively, you could just speed up earth, but it'll mean that the time dilation is same everywhere on the planet (aside from other interesting/devastating consequences). Speeding time up on earth in comparison to rest of the universe is much trickier but if we were to speed up the time on earth compared to another planet or a region of space then it's doable - Just put the massive celestial object close to the region of space and you could, in theory, say that the time on earth has sped up compared to that region of space. The region must be far enough from earth so that earth is only nominally affected by the massive object. ]
[Question] [ ## Context NASA commissioned some awesome, vintage-style prints a while back advertising the colonization of Mars. [![enter image description here](https://i.stack.imgur.com/43NiD.jpg)](https://i.stack.imgur.com/43NiD.jpg) Three of them stood out to me because they depicted colonization of the moons of Mars - Phobos and / or Deimos. [![enter image description here](https://i.stack.imgur.com/Qb6yF.jpg)](https://i.stack.imgur.com/Qb6yF.jpg) (The rest of those prints are [here](http://mars.nasa.gov/multimedia/resources/mars-posters-explorers-wanted/), and they're free) I would like to have colonies on these moons in my world, but the moons are extremely small relative to our moon (or even Mars) so they have very low gravity. Knowing NASA, there must be a scientific basis for these images, but intuitively, this does not seem possible. --- Is there any scientific basis behind strong, gravity-like effects in these locations? If not, what can be engineered to allow "gravity" in such open spaces? Note: "Enough gravity" means that people won't escape the planet with everyday movement; low gravity should also not be extremely inhibitive (ex. flying 10 feet into the air when you take a step up) [Answer] # How to calculate surface gravity Surface gravity ($\hat{g}$) is a function of the mass ($M$) and radius ($r$) of the planet: $$\hat{g} = \frac{G\cdot M}{r^2},$$ where $G$ is the universal gravitation constant $6.67\times10^{-11}\,\frac{\text{N}\cdot\text{m}^2}{\text{kg}^2}$. If you assume your planet is in hydrostatic equilibrium (a good assumption for any planet with noticable surface gravity), then mass is in turn a function of radius and density ($\rho$): $$M = \rho\frac{4}{3}\pi r^3.$$ Put these together and you get: $$\hat{g} = \frac{4}{3}\pi G\rho r.$$ Proof. The radius of earth is 6371 km; the density is 5515 kg/m$^3$. $$ \hat{g}\_{earth} = \frac{4}{3}\pi \left(6.67\times10^{-11}\,\frac{\text{N}\cdot\text{m}^2}{\text{kg}^2}\right) \left(5515 \frac{\text{kg}}{\text{m}^3}\right) \left(6371000 \text{m}\right) = 9.81 \frac{\text{m}}{\text{s}^2}.$$ # Surface gravity of Phobos and Deimos To calculate surface gravity of Phobos and Deimos, we need the density and radius. Phobos has a mean radius of 11.3 km and density 1876 kg/m$^3$; Deimos is 6.2 km and 1471 kg/m$^3$. Since both objects are irregular (not perfect spheres) there is variable gravity on different points of its surface, but surface gravity at mean radius for Phobos is 0.0003g and Deimos is 0.0002g. # How to stay on the surface The escape velocities for Phobos and Deimos are 8 m/s and 5 m/s respectively. That is obviously very low. If you can jump half a meter (as in a box jump), your initial velocity is about 3 m/s. So Michael Jordan could definitely jump off these moons, and I probably could have too, back in high school. In order to stay on to something you have no business staying on, we should use the same thing people use on Earth: ropes. It wouldn't be easy to just walk around, but if you had work to do on the surface, get there in a space-suit with micro-thrusters to keep you from drifting away accidentally, then attach your harness to a secure point on the moon's surface and get to work. Astronauts use bungee cords on tread-mills to give a more Earth-like sensation of being pulled down. Some thing like that could be used as well, in addition to the safety harness, to give you more traction with the ground in your immediate work area. [Answer] Colonizing either of Mars' moons would be no different than colonizing a large asteroid. Essentially, that is what they are. There are lots of concepts for asteroid colonization, including encasing the entire thing in a gigantic dome that would allow you to pressurize the environment and would contain objects and people that would otherwise go flying off into space. Without going into the vast cost and size involved in totally encasing the surface of one of these moons with a dome, we could still have a very large dome covering some significant part of the moon, which would allow us to use the moon basically as a really large space station with fairly cheap (in terms of fuel cost) docking/launching for ships. It might make a good repair depot for vessels of different types, with custom built ship cradles and a nice dome town with a lot of velcro and "nerf" like surfaces that keep people from giving themselves a concussion on the top of the dome when they jump too high. Unlike repair docks for a ship in high orbit, tools would not just float away forever if dropped, but would collect at the floor of the "hangar" area. It would be easier to scoop up loose pieces and parts at the end of the day. [Answer] I don't know what walking in microgravity would be like. But in the second image the worker appears to be standing on a metal platform; magnetic boots would secure her to the platform. In the third image the farm floor could also be made of metal. The only other way to gain a gravity on these moons would be to hollow out some tunnels and spin the moons quite quickly. You could then walk on the sides of the tunnels closest to the surface (almost like a reverse gravity). ]
[Question] [ In many RPG games, there exists a (usually evil) creature whose body mass primarily consists of a giant eye, and is usually at least the size of a human head. Sometimes it has wings and flies, sometimes it has tentacles and floats through the air. Most of the time, the eye's gaze is dangerous in some way — whether it shoots lasers or otherwise incapacitates a target. Is there a realistic way such creatures could evolve? How close could we get within the realm of realism? [Answer] Ooh... Interesting problem. I'm going to focus on a potential evolution path rather than just saying 'it's unlikely' because it's more fun! The biggest issues are where to put the organs and how to make it float. If we look at traditional images of ~~beholders~~ floating eye creatures we can see that they're depicted as having a mouth, so we can assume they eat and don't photosynthesize etc. The sharp teeth also suggests carnivore, which helps with the energy requirements somewhat. The space given over to the mouth also gives an opportunity for a compact in-situ digestive system, somewhat similar to a snake crossed with a pelican. Once prey is incapacitated (which I'll get to) the ~~beholder~~ floating eye creature reticulates its jaw, expands its 'digestive pouch' (gullet merged into stomach), swallows the prey like a snake and sits, grounded, while it digests it. When it's done it spits out the bones and flies off. Our ~~beholder~~ floating eye creature has a vestigial anus, just as a point of interest. Obviously the above suggests an evolutionary track from a snake, or an ancestor of snakes, so we're likely looking at a cold blooded creature. From here we get a possible evolutionary track for flight, as creatures that can rise above low lying fog etc would be able to stay active longer than ones that can't, matching up neatly with the hunting patterns of the ~~beholder~~ floating eye creature (why hunt prey when you can eat it as it sleeps?). There are a number of gases that could help with the floating, some of which may be byproducts from the digestive fluids used. This creature is grounded while eating, and eats to avoid being grounded. How paradoxical. The other organs can be distributed neatly around the flesh of the creature. There's a lot of surface area to fill with (very flattened but still functional) organs, and if you're happy moving some functions out into the tentacles (a-la octopus) then things like liver/kidneys etc can be shifted fairly easily. The brain is a little trickier, as it needs to be fairly localized, but this gives us a wonderful reason for why they have such big eyes in the first place. Flies (and many insects) do a lot of processing in specialized neural clusters fastened directly to the eyes. This has a lot of advantages for them, as it lets them react faster as the distance from input-reflex is much shorter. Now imagine a lizard living in low lying fog. It might have only a millisecond before it can see a predator dropping down from above, so it needs to be able to see, think and react very quickly to survive. As such: It develops specialized processing that links to it's defensive system (again, I'll get to it in a second) and is situated directly behind the eyeball (I can't explain the mono-eye, we've got to go very far back in the evolutionary chain for that). Over time this eye-brain develops, and the creatures head adapts commensurately. The musculature for ocular motion is a tricky one, but it's possible if you assume the creature hasn't got a massive amount of 'scan' to the eyeball (it can't track massively far, preferring instead to turn it's head) The larger surface area allows the creature to utilize some of the previously wasted gases for lift, and it starts to use a combination of jumping and tentacles to 'fly'. The body and legs become vestigial, and you have your ~~beholder~~ floating eye creature. One major concern is the weight of the eye, but it's not inconceivable to have an eye held up by struts instead of fluid (though it is weird. Perhaps a part of the 'single eye' evolution way back in the dawn of time?) Now the defensive system becomes a hunting system for immobilizing prey. What is the defensive system? A series of tentacles with stings on the end. In the early lizard the eyes were used to rapidly orient the stings towards incoming predators, reducing the amount of energy needing to be expended on growing all-round spiny coverage. In the later lizards where the eye is taking more direct control of signal processing the tentacles become a predation system as well as a tool for manipulation and flight (flight might need some specialized 'paddle like' tentacles) On the subject of using the eye as a weapon: I can't think of any way to make it directly offensive, but if the eye is photo-luminescent it would act as a lure for any stray creatures lost in the fog, enabling a grounded ~~beholder~~ floating eye creature to lure, sting and devour a creature to refill its floats. I think that would count as dangerous. TL:DR : It evolved from a one eyed lizard in a very foggy place. This explains its fondness for crypts, dungeons, and mysterious mists. Addendum: On the eye structure: A fish-like creature in the dim and distant past was predated upon by smaller fish that would nip at its soft fleshy eyeballs. Over time those eyeballs grew hardened and chitinous, leading to diminished visual acuity but stronger eyes. As these eyes formed they developed internal strutting to hold the eyeballs rigid rather than risking cracking/stress injuries. When this fish's ancestors eventually made it to land their eyes drained of most fluid, leaving them with a hollow (light) eyeball and terrible eyesight. This explains the lizard's weird requirement for faster eye-reaction time (it's almost blind), it's predilection for foggy places (Why live where you've got the shortest vision? Go somewhere everyone is blind!) and (almost as an afterthought) The unique angular patterns some ~~beholders~~ floating eye creatures seem to have in their eyes. [Answer] Usually these things are depicted much like a human eye, i.e. with a lens in front — which means that the body needs to be hollow, which leaves no place for muscles, a digestive system or a brain that could do anything with the sensory input. So this is not very likely, especially if you want it to fly. If you are prepared to settle for a spherical thing that responds to light I could imagine a [Volvox](https://en.wikipedia.org/wiki/Volvox)-like colony of light-sensitive cells that respond to changes in brightness — they could "see" people in as far as people block out some light. This colony might even evolve in a way that most cells are opaque and only a "pupil" is transparent — this would allow the colony to better orient itself towards the light (move until the transparent bit is fully lit) and might give the impression of an human eye. Volvox is aquatic, but maybe our hypothetical cells produce a gas that is lighter than air and lets them float through the air in the way of a helium balloon. I cannot imagine a mechanism that lets organisms shoot laser beams, but there might be [nematocysts](https://en.wikipedia.org/wiki/Cnidocyte) placed around the "pupil" that sting in the way of jellyfish and thus incapacitate prey or attackers. Updated: okay, there seems to be an all-eyeball creature (although it's not gigantic and I doubt it would scale well): [Single cell eyeball creature startles scientists](https://cosmosmagazine.com/life-sciences/single-cell-eyeball-creature-startles-scientists) [Answer] Basically, no, not literally. They don't physically make any real sense, as animals. In fact, the point seems to largely be that they don't make sense. Almost everything about them is the opposite of making sense. What makes sense about them is that they're terrifying, but they're the kind of terrifying that is scary because it defies reality and makes no sense, so seeing it in reality would tend to be extremely alarming, not just because it's icky but because it violates our understanding of how things are supposed to work (and NOT work)! A central theme of horror is the unknown, the unexpected, the unknowable, the incomprehensible, the unimaginable, the unfathomable, and things that seem to contradict what we think we know about our world. So... maybe the reality is different from the perception. Such a thing can exist if it is a nightmare, an illusion, magic, something else disguised to look like something that shouldn't be able to exist, and/or a horror story that people believe in and are too scared to go anywhere near it to verify it. As a conjured horror created intentionally, it makes sense if it can be engineered or magicked or conjured or whatever, but not as a naturally evolving animal. [Answer] It is possible that a creature with massive eyes could eventually drop the need to eat. As a result, it could eventually move past most of the rest of its form. It's also possible that the eye could be designed to eject from its body and eventually such an eye could start to reproduce and/or survive on its own. In real life, some creatures like frogs can shoot poison or blood from their eyes. This could be adapted to be even more dangerous. You could also intensify the crystallin levels in the eye that form the lens and use it to concentrate a laser... With a little magic in there somewhere. [Answer] Does the housefly count? Most insects have compound eyes along with simple eyes and if you calculate the ratio of eye size versus total body size, you would find that their eyes are the largest in all animal kingdom. [![enter image description here](https://i.stack.imgur.com/XXaxC.jpg)](https://i.stack.imgur.com/XXaxC.jpg) Or Ophthalmosaurus (a type of ichthyosaur)? <http://ncbi.nlm.nih.gov/pmc/articles/PMC1771016> states that (in vertebrates) this animal had the largest eye-to-aggregate size ratio. Considering that I am editing my answer to include details and reference links, it is also appropriate to answer a logical question in the comments here: *@YoustayIgo Is there anything which prevents eyes that size to go along with an even smaller body? Just because it hasn't been done that we know of doesn't mean it can't. – DoubleDouble* There are two sides of this question. One scientific and the other logical. I would answer the scientific side first. As far as I know there has been no detailed research on the factors which limit eye size. If critic finds that a larger eye size is possible with a creature smaller than Ophthalmosaurus (19 feet) then he/she should present that research for the benefit of all members. Even if the said research does not exist, the critic can still research the need for larger eyes, the resource requirements and the risk factors involved and post them here. It would not count as a scientific research, but it would be still better than simply raising a meaningless question without any scientific backing. As for the logical side, the answer is simple. No, as far as we know, there are no logical constraints for such a creature. But that does not mean that such a creature *does* positively exist. For example, one could theorize that logically it is possible that one group of mammals quickly evolved into paleo-humans during the time of dinosaurs and lived alongside. They used to ride on suropods and hunted mega-theropods like T.Rex for sport. Unfortunately, one day they encountered a cookie-monster who killed them all and erased all evidence of their existence so that we don't find any evidence of their existence. While it is theoretically possible that the above absurd tale is true, no sane person would give it a second thought. The same applies for a giant-eyed creature, smaller than 19 feet. Logical possibilities about organisms' design are not worth consideration unless there is dedicated scientific research backing them or the discovery of any evidence for the presence of such creatures. Here is an image of Ophthalmosaurus. [![enter image description here](https://i.stack.imgur.com/Y4osY.png)](https://i.stack.imgur.com/Y4osY.png) ]
[Question] [ So, as the title suggests, I have a reptilian alien species capable of human-tier thought. Anatomically, they are centaur-like (four legs on the ground, two manipulating limbs up top), standing slightly taller than humans and having roughly twice the body mass. I imagine that these creatures would need a good amount of energy to maintain human-level intelligence and support a human-like society, so they are omnivores; their lower body is of a canine build, letting them run fast enough to hunt large prey animals in packs. I presume that all this energy expenditure can only be supported by a warm-blooded metabolism, but this is where I ask my first question: am I wrong in this assumption? Is it feasible for a cold-blooded sapient species to exist? If you think it is, please shoot me your ideas, because I'm very curious. My second question is less about sapience than it is about thermodynamics. Can a warm-blooded creature reasonably evolve without requiring feathers or fur to maintain its body temperature? I don't think it's a coincidence that mammals and birds, the two living classes of vertebrates that are warm-blooded, are also the ones with a coat that can either insulate or ventilate as appropriate. My (warm-blooded?) sapient species is scaly. No coat. Right now I'm imagining that their scales either (1) are very thick/insulating on their own or (2) tessellate together in a way that traps a layer of tiny air pockets. Since this scale layer can't vent itself in case of overheating the way fur or feathers can, they have a "mane" of fleshy tentacles on their heads that are completely scale-free and act as heat sinks. If any of these mechanisms are insufficient, lacking, over the top, or otherwise incorrect--for example, should the heat sink tentacles sweat?--I would love to hear your suggestions for improving them! [Answer] It depends on their environment. If you think about it, a "cold-blooded" animal (which is properly called an [ecotherm](https://en.wikipedia.org/wiki/Ectotherm)) has *more* energy available for brain power than an [endotherm](https://en.wikipedia.org/wiki/Endotherm) in some cases. They're not using energy to heat themselves, instead they get their heat from their environment. If the animal lives in an environment that has a fairly stable temperature (in a range conducive to its metabolic processes) then it doesn't need to waste energy heating itself and can more easily spend it on brain power (among other things). Living underground or underwater are excellent examples of stable temperature environments. > > Is it feasible for a cold-blooded sapient species to exist? > > > Absolutely, given a stable environment, it might even be more likely. > > Can a warm-blooded creature reasonably evolve without requiring feathers or fur to maintain its body temperature? > > > Absolutely. If they live in an environment that is close enough to their target body temperature or they make use of tools or environmental factors (like covering themselves in insulating mud) then they don't need fur or feathers to maintain that temperature. [Answer] Interestingly enough, the octopus is listed as one of the top ten when it comes to intelligence in the animal kingdom, so I don't think it is unreasonable to assume a reptile might achieve sapience. If you are using earthly critters as models it would be a lot more difficult, as mammals have a number of advantages that let them win out over other species, but you could either give these particular reptiles a competitive advantage (poisonous secretions that take them off the dinner menu, or maybe a geographic isolation that removes mammals as competitors) As to your second question, elephants don't have feathers or fur. Nor do dolphins or whales. All of these are warm blooded and quite intelligent. There is also a species of warm-bloods which have scales, the pangolin. ]
[Question] [ Say we had a planet which was a gas giant. Is it possible that at the core of the planet where meteors, asteroids, and comet debris had collected that there could be a layer of atmosphere similar to that of Earth's? If this could happen, could there be a temperature friendly to super strong multicellular organisms. Also, what would it take to leave the atmosphere? [Answer] I don't think we're going to find any evidence ([like TimB did for this question](https://worldbuilding.stackexchange.com/questions/4729/is-jupiter-sized-planet-plausible-in-habitable-zone)) that life does exist on extrasolar gas giants, but we can at least use some logic to figure it out. No. First, the cores of gas giants are nothing like asteroids, comets, or even terrestrial planets. [Jupiter's core](http://en.wikipedia.org/wiki/Jupiter#Internal_structure) is thought to consist of rock, surrounded by metallic hydrogen - in a liquid state, known as a supercritical fluid. Temperatures there are thought to reach a whopping 36,000 K - just at the outer edges - and pressures are thought to be about 3,000,000 Pascals, much greater than on Earth. [Here's](http://upload.wikimedia.org/wikipedia/commons/b/b5/Jupiter_diagram.svg) a guide to the interior of Jupiter (way too warped to put here). [Saturn's core](http://en.wikipedia.org/wiki/Saturn#Internal_structure) isn't much different: a ball of rock and ice surrounded by hydrogen and helium at enormous temperatures and pressures. [Uranus's core](http://en.wikipedia.org/wiki/Uranus#Internal_structure) is only at about 5,000 K and a measely 800,000 Pascals, but that's still very harsh conditions - too harsh for life to survive. [Neptune](http://en.wikipedia.org/wiki/Neptune#Internal_structure) is much the same. Any extrasolar gas giants probably have very similar internal structures. > > there could be a layer of atmosphere similar to that of earths. > > > No. The conditions anywhere near the core are fairly bad. > > Also what would it take to leave the atmosphere? > > > You're looking for [escape velocity](http://en.wikipedia.org/wiki/Escape_velocity). At a distance $r$ from a body with mass $M$, the escape velocity is $$v=\sqrt{\frac{2GM}{r}}$$ Given that the cores are generally many more times massive than Earth (though Neptune and Uranus may be exceptions) and are also bigger than Earth, I'd say that the answer would be that it would be very, very hard (i.e. impossible), taking into consideration the temperatures and pressures down there. Assuming, however, that there somehow is life in the core of this planet, and some of the life forms want to get off the core, here's what they'd face when trying t build and fly a spaceship off the planet: * Temperature. [Iron](http://en.wikipedia.org/wiki/Iron) melts at 1811 K and boils at 3134 K - and the temperatures here are an order of magnitude higher than that! I haven't been able to find figures for steel, but I'm guessing it wouldn't do you any good here. Copper, brass, and just about any other metal you can think of would most likely be in some sort of gaseous state. * Pressure. Same problems here as with pressure. Landers on [Venus](http://en.wikipedia.org/wiki/Venus), with its surface air pressure of 9.2 MPa, have been crushed in a very short period of time. If the temperature didn't get any materials on Jupiter's core, the pressure would. * Drag. Materials aside, you're going to have to get through tens of thousands of miles of gases here. I can't find the exact figures for the atmospheric gases, but I would assume that their density would make it very tough to get anywhere. A lot of energy would be lost to atmospheric friction, not only taking away energy but heating up the spacecraft. --- TimB recently brought up a good point in a comment: > > Hmm, the thing this answer misses is that there is a band as you come further out of the atmosphere where the pressure and temperature are actually reasonable. The question then arises as to whether life could evolve there. > > > We did have [a question](https://worldbuilding.stackexchange.com/questions/2856/life-on-a-planet-with-multiple-gas-layers) a while back about whether or not life could form on a planet with multiple gas layers. There was a division over this: TimB said it was unlikely for anything bigger than bacteria, and I came up with a whimsical scenario involving pufferfish polyps. Bacteria could definitely live up somewhere in the upper atmosphere of a gas giant. I don't think there's any doubt about that. But any life in the gas giant's atmosphere would have to be high up, and therefore either flying or lighter than air. The first is possible but only if the creature was introduced pre-evolved. The second is less likely. Bacteria are your best shot. Also, the life-forms would have to breathe an odd mixture of gases. Their best bet would be [hydrogen and helium](http://en.wikipedia.org/wiki/Atmosphere_of_Jupiter), neither of which is conducive to life, although they could also go for methane, trace amounts of oxygen, or ammonia-based compounds. There's also a bit of water, although that would be useless for respiration. Quite frankly, I don't think complex life could evolve in the atmosphere - or anywhere on a gas giant! [Answer] Actually, it has been suggested that complex, multicellular life could evolve to float in the atmosphere of a gas giant. From single cells floating in hospitable bands of the atmosphere, we could reasonably expect to go from those to multicellular organisms capable of moving about under their own power. As to whether such life could leave the atmosphere... This is a very complex question. It would be necessary to construct infrastructure that could float in the habitable bands of the atmosphere - anything too heavy could drop down out of reach, and anything too light could float up out of reach. However, if the materials were available, it may be possible for beings in these conditions to explore both upwards and downwards, and potentially even leave the atmosphere entirely. [Answer] As others have mentioned, it could be possible for life (as we know it, maybe, kind of) to survive in Jupiter's atmosphere. Don't forget, however, that Jupiter's magnetosphere also produces a LOT of bad radiation. That's a big theoretical obstacle to any kind of human colonization of Jupiter's moons, and it would be a really big hazard for any kind of life in or around the planet. [Answer] In the novel [2061: Odyssey Three](http://en.wikipedia.org/wiki/2061:_Odyssey_Three) from Arthur C. Clarke in the end there is the consciousness floating to the surface of jupiter and saw clouds who couldnt make fire and hence were compelled to stay on a nomadic civilizational status. This was taken into consideration when deciding whether to deploy the monoliths on that planet. ]
[Question] [ Is it possible to use a whip to seize things or persons like depicted in the Indiana Jones movies (e. g. the whip is wrapped around a root so he can swing over an abyss)? For example a slave trader using a whip to recapture escapees, or is this only possible with bolas or a lasso. [Answer] # Yes This is called "Bullwhip Cracking". It's not easy but definitely possible. You can see this demonstrated [in this YouTube video](https://www.youtube.com/watch?v=YAHExJE53gs), and you can see the swinging from a tree branch [in this video](https://www.youtube.com/watch?v=6I_ESNuLwGA). As far as capturing people (especially escapees who are running away, and have arms to grab at the rope when it hits them), a lasso or bolas would be much easier. As for extreme punishments, bullwhip cracking (depending on the whip's design and material) could wrap around an arm or leg resulting in as much as broken bones. [Answer] # The short answer is...yes In an [article by Wired Magazine](https://www.wired.com/2010/01/st-howto-oscarpool/), these instructions are provided: > > 1. Skip the toys. > > > Look for a 6- to 8-foot-long whip with a braided core. The best are made from kangaroo hide. > > > 2. Take your stance. > > > Imagine you're straddling railroad tracks. The whip should travel parallel to the rails, and the target should be a bit closer than the length of your whip. Use caution: The tip can cut to bone. > > > 3. Load and lock. > > > Stretch the whip out in front of you, arm extended and pointed at the object. Now yank your hand up to 12 o'clock. The whip will fly over your hand and unravel behind you. > > > 4. Throw down. > > > When you feel a tug, lower your forearm — easy now, let the whip do the work. It'll roll forward just to the side of your body. As it unfurls, squeeze the handle. > > > 5. Crack and drag. > > > The tip will extend just beyond the target; as it recoils, it'll wrap itself around the object. Pull the remote toward you slowly. Next lesson: cracking open a beer. > > > Swinging from a whip involves the same basic principles. Even a child can do it: <https://youtu.be/hSV-XIxSwHM> Snaring a captive would (I imagine) follow the same methodology and would not incorporate any cracking. Whip cracking can split flesh to the bone; as you can see in the video above, merely snagging is a fundamentally different (and gentler) technique. A whip is probably not the most ideal instrument for this purpose, however. Bolas and lassos have several advantages, including reach, but there is actually a weapon specifically designed for this purpose: it's called the man catcher. You can see a video on the subject [HERE](https://www.youtube.com/watch?v=VTZ9bB086Mg) ]
[Question] [ This is my first time posting on Worldbuilding, so please, if I make any mistakes or don't provide enough / the proper type of information, do not hesitate to tell me. Introductions aside, let's jump right into the good stuff: Assume for a moment that you are in a fantasy world where magic is quite common, and everybody lives in harmony, doing magic-people things. Only, instead of everyone living on one conjoined land mass - for example, a continent - they all live on separate, spread out floating islands... in different planes. The only way to get from one island to another is through a portal to that island / plane, which in a magical society is quite easy to produce. The question is, how would people 'map out' locations in this world? Directions and getting to places are still things, as the portals would most likely only work with "nearby" planes; however, how would the local folk create easily visualizable maps of their area (whether on paper or anything else)? Each island would be rather small, and while there might be a few planes with more / larger islands, most of them would only contain one or two with enough room for a couple of houses at most. Any help at all is appreciated. [Answer] Have you seen the modern map of the London Underground?: [![enter image description here](https://i.stack.imgur.com/Dg4Sj.gif)](https://i.stack.imgur.com/Dg4Sj.gif) It has nothing to do with the distances involved, all that is important to this kind of map is what links to where. Assuming that the portal system is reasonably static then this format would work quite well. Supplemental to this there are other maps for individual "stations" in the case of your maps these would be the habitable islands and they could contain notes as to the planar position of the individual spaces in question. If, on the other hand, the portals are semi-fluid, linking to fixed sites but not always open in any given formation then it gets a little more complex, you can map the islands and the sites where they can be connected to each other but, without magic, not the current configuration at any given time. The map is then very similar to the underground style map but has more linkages representing the possibilities of the network. If the portals are entirely fluid but limited in range then you need some form of array that gives relative distances so that people can open the portals they need. So something similar to this would then be useful: [![enter image description here](https://i.stack.imgur.com/vOe7f.jpg)](https://i.stack.imgur.com/vOe7f.jpg) [Answer] Islands would likely be mapped to separate pages. The pages would then be grouped by either how easy it is to get from one island to another (especially so with permanent portals) or by islands that have a useful group of features (island of cows connected to the island of wheat fields, etc.). I would imagine that every group would sort the islands differently. Heck, you could have someone who bundles them by the color of the foliage. [Answer] There would be lots of different attributes that could be used to map the different portals and different attributes would be of interest to different people. Those in a hurry want the fastest route, those with larger or smaller amounts of money want the cheapest route (if there are any tolls), those with a very specific purpose in mind want to find specifically what they want (nearest wand shop say). Each of these would need a different map highlighting the best routes from their perspective. Each attribute is effectively a different dimension. Perhaps several tube like maps would be used for the more popular attributes, but the obvious solution would be to use a computer that could display the map orientated by any attribute you wished a bit like the internet or a magical version of it. Just imagine your key attribute and the map appears. [Answer] It's a world of magic, so the possibilities are many, and most likely will appear to different groups in vastly different ways. Since the portals work via magic on demand, any mapping system that somehow names or symbolizes each plane will work. Your people only need to agree on a naming or signing convention, teach it to everyone wanting to travel that set of planes, and also create an automatic mapping updater spell that publishes any changes to the map to prevent portal crashes. This way, anyone connecting a portal from plane (pickaname) to plane (differentname) sees all possible routes and nearby potential alternate destinations in a visualization that best works for them and still gives them the needed information. The medium the map appears on can be paper, grains of sand on a metal plate, or the sky itself. ]
[Question] [ What makes an animal suitable for domestication? I know it has something to do with the danger to productivity ratio. But this is not helpful for fantasy animals in the worlds we build. What factors or ratios can I use to help determine what fantasy animals are suitable for domestication? [Answer] So, putting together all the excellent points made in other answers, I would say that any animal can be tamed and used in a symbiotic relationship with people. It is more likely to happen if it is harmless enough that the occasional bad behavior (panic or aggression related) can be tolerated. It might be that the animal is docile by nature, or it might be that it is small enough that it can't cause much damage. Which animal will be domesticated, shaped over the generations, is decided by practical considerations: of how much value is a relationship with this species? Thus you might have things that are cute and cuddly "straight out of the box" being domesticated as companions. Animals with a strong sense of hierarchy (like canines) would be bred to be tools and helpmates. Food animals would be bred for their flesh and probably temperament. Each species would be bred to enhance and improve those characteristics which make it useful. Why have we never domesticated tigers? Because they are dangerous and even the most gently raised of them has the potential for turned on its handlers. But what if the tiger was able to teleport not only itself but also anyone holding on to it. Would we have domesticated them? My guess would be yes. Even if their temperaments never improved much the value of instantaneous travel would be worth the occasional mauling. Now, as an aside, that doesn't explain why the Egyptians put so much work into cats, but maybe, since all "house cats" are descended from a very small population in a very specific area (<http://archaeology.about.com/od/domestications/qt/cat.htm>) it might be that someone found a particular strain of feline that lent itself to domestication and they just took advantage of it. [Answer] If I Google for "what animals can be domesticated," the 3rd [link](http://www.livescience.com/33870-domesticated-animals-criteria.html) is quite helpful, "Why Can't All Animals Be Domesticated? -LiveScience" (all of the first links are very helpful to you, but that one seems most well addressed to the exact wording of your question) From that article, they identify 6 major characteristics of a domesticatable animal: * Cannot be picky eaters * Reach maturity quickly * Willing to breed in captivity * Docile by nature * Cannot have a strong tendency to panic and flee * Conform to a social hierarchy There are counterarguments (the domestication of dogs from wolves lead some to question if "docile by nature" is a valid criteria), but it seems to be a reasonable start. There is another theory going that the act of domestication is a particular neural crest deficiency that eventually occurs through the mutation process. Apparently it was [noted](http://carta.anthropogeny.org/events/sessions/evolution-human-vocal-tract) since Darwin's time that domesticated mammals all show phenotypic characteristics of floppy ears, smaller teeth, and shorter snouts. It is now known that these traits occur as a result of changes in how the neural crest develops as a fetus. These changes also have brain effects, such as decreasing fight or flight responsiveness. Any fantasy creature which cannot, for some reason, undergo such a change would indicate that that species is harder to domesticate. [Answer] Any animal can be domesticated. All it takes is time... 10s of thousands of years. What really drives domestication is a symbiotic relationship between the animal and human. House pets get shelter, food, water, and affection. However, they provide services for humans. For instance dogs bark at strangers to provide security. Cats kill rodents that might steal our food. Horses, do manual labor. A fantasy animal would be no different. Obviously, humans would provide food, water, and shelter. All you have to do is think of what that fantasy animal would provide for humans. Pet gorgon? Sure, if you need lots of statues. [Answer] I would add one more criteria: Does not regard human-sized objects as food. Thus we can domesticate the housecat (although it actually seems like they self-domesticated) but not the lion or tiger. [Answer] It depends on your threshold for suitable in regards to [domestication](https://en.wikipedia.org/wiki/Domestication). For possible, the only things needed are, 1. Some way to gain substantial leverage over the other creature in regards to survival (food, shelter, etc) and reproduction. 2. The ability to conform to some kind of social hierarchy where you the "domesticator" have the ability to be the gatekeeper of their needs to live and reproduce, be that by force or by training or bonding. That's it as far as domestication requirements goes. Now, if you want a good pet, that's an entirely different question :) And quite a bit more subjective... ]
[Question] [ A class of organism, lithotrophs, use minerals (inorganic substrates) for energy conservation/reducing equivalents in biosynthesis. However such organisms on Earth are limited to single-celled prokaryotes in the Domains Archea or Bacteria. The question is, are higher organisms, specifically animal-like lithotrophic organisms (as opposed to plant-like or fungi-like) possible? If yes, what would be the evolutionary justification? (i.e. How would the organism work?) The main problem with higher organisms of this kind, is the lack of useful inorganic substrates that are also abundant. Let's assume that the lithotroph only uses minerals for energy conservation and not as a reducing equivalent (it either uses organic sources, or CO2 fixation probably the former since its animal-like). Let's also assume relative abundance of the necessary inorganic substrate (but not as much as gaseous substrates like O2), and unavailability of better oxidants (again, O2) [Answer] I've been slacking lately on [biology](/questions/tagged/biology "show questions tagged 'biology'") questions, so I'll try my luck on this one. Good news! These things aren't so far-fetched! Meet the [giant tube worm](http://en.wikipedia.org/wiki/Giant_tube_worm) (see also [here](http://news.nationalgeographic.com/news/2002/10/1028_021028_TVtubeworm_2.html)). [![](https://i.stack.imgur.com/IbT6X.jpg)](http://deepseacreatures.org/images/stories/giant-tube-worm.jpg) (Original image source: <http://deepseacreatures.org>) These things are, believe it or not, animals. Not plants. Not fungi. Animals. Females release eggs, males release sperm, the two joyfully meet, and the resulting offspring settles down on a rock somewhere in the deep, dark, despondent dreary depths of the lower levels of the ocean. [They can grow up to 8 feet long](http://www.seasky.org/deep-sea/giant-tube-worm.html) and are thought to live for hundreds of years, though, like so many things at the bottom of the ocean, nobody really knows. Giant tube worms like [hydrothermal vents](http://en.wikipedia.org/wiki/Hydrothermal_vent). These vents can emit water (often as a supercritical fluid) at temperatures of over 400°C. They also happen to form the backbone for a vast undersea network. Why? The water they emit is mineral-rich, containing, among other things, [H2S](http://en.wikipedia.org/wiki/Hydrogen_sulfide) - hydrogen sulfide. Certain types of bacteria love this stuff, and they can undergo [chemosynthesis](http://en.wikipedia.org/wiki/Chemosynthesis). These bacteria are [lithotrophs](http://en.wikipedia.org/wiki/Lithotroph), undergoing one of several different reactions. The upshot of all this is that giant tubeworms need these bacteria for survival. They have no mouths or digestive system, but they can use the result of the bacteria's chemosynthesis to survive. "Ah," you say, "but these tube worms are not directly lithotrophs. They're merely in a symbiotic relationship." Think about [mitochondria](http://en.wikipedia.org/wiki/Mitochondrion#Origin). One theory of their origin states that they were originally prokaryotes. Yet now they serve an incredibly important purpose in many eukaryotes. What's to stop giant tube worms from eventually treating lithotrophic bacteria the same way? There's your evolutionary justification. [Answer] We tend to think of animals as organotrophs and we assume that only bacteria and archaea can be lithotrophs. It's true that there are no animals known to rely on inorganic compounds as a major energy source. Would it be possible for an animal to get its calories from an inorganic source instead of from carbohydrates, lipids, and proteins? Many of the energy sources used by lithotrophs (e.g., hydrogen sulfide or iron) would be toxic to most animals if consumed in quantities large enough to supply the body with energy. Sulfur is considered relatively non-toxic and is rich in energy - lithotrophs obtain 149.8 kcal/mol from the oxidation of sulfur (see Wikipedia page on lithotrophs) (Sulfur has an atomic weight of 32.06, so that gives us 4.67 calories per gram). Could animals use elemental sulfur as an energy source? Animals do get sulfur in their diets (in their amino acids), but using elemental sulfur as a significant calorie source would mean consuming several hundred grams a day. There are few reports of anyone ingesting even a couple of grams per day. People have just assumed that much sulfur is toxic since it can react with organic compounds to form deadly hydrogen sulfide. Whether you could prevent this interaction by not eating organic compounds with the sulfur is uncertain. There are animals that benefit from sulfur oxidation, like the tubeworm, but they have bacteria inside them that oxidize the sulfur compounds for them. However, one species of ray-finned fish (S. reidi) can oxidize hydrogen sulfide in its mitochondria (just like glucose) to produce ATP (a store of food energy).[<http://sulfide-life.info/mtobler/images/stories/readings/grieshaber%201998%20annu%20rev%20physiol.pdf>, see pg 43]. Whether sulfide oxidation can contribute a significant amount of energy to these animals remains unanswered since sulfide inhibits respiration at high enough levels (see pg 45). We humans can most definitely oxidize sulfur in our mitochondria too. We have all the enzymes needed to oxidize elemental sulfur all the way to sulfate, including sulfur dioxygenase (to oxidize sulfur to sulfite) and sulfite oxidase (to oxidize sulfite to sulfate). And we conserve energy from the process. That's right. When our cells oxidize sulfur, we actually make ATP (see, for instance, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1347283/>). ]
[Question] [ This question may be a bit broad, but I'm basically wondering what minimal things humans need to have in an atmosphere in order to survive. Let's assume we have Earthlike gravity, and are only dealing with perhaps the first 10 or so elements. Life does not have to have developed there. I'm especially interested in what kinds of atmospheric conditions one could expect to find occurring naturally on a solid planet, and what elements/compounds need to be there or not be there for humans to survive, at least for up to an hour. [Answer] Essentially, you need the O2 and the CO2 from the air. * The O2 is vital for basic functional purposes, such as [ATP manufacture](http://en.wikipedia.org/wiki/Cellular_respiration). * Trace amounts (parts per million) of CO2 [regulate blood pH, and perform a few other vital roles.](https://biology.stackexchange.com/questions/9993/is-there-any-use-of-co%E2%82%82-in-human-body) See the link for a detailed answer. * Some inert filler to make up the bulk of the gas mix. In terms of atmospheric pressure, think of the equivalent of being on [a tall mountain](http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html). So you can probably live around 80kPa, but actually doing any work would be hard, and going much lower you get into the [deathzone](http://en.wikipedia.org/wiki/Effects_of_high_altitude_on_humans#Death_zone). Alternatively, you can increase the O2 concentration to increase the partial pressure of O2, but that gives you only a little bit of wiggle room since once you increase it past 30%, humans (especially hair and fat) become about as combustible as a paraffin torch. Not the best environment to be doing welding, say. Not to mention the free radical and vasoconstriction issues that become pervasive once O2 climbs above a certain threshold. Presumably, you might want to add a no-poison-gas condition, but that can be alleviated by wearing a gas-mask and a basic body-suit. I should probably add that without a massive oxygen manufacturing process, biological or synthetic, the oxygen would react with (oxidize) exposed iron and other elements and reduce from the atmosphere, so an oxygen atmosphere (beyond trace amounts - ppm) is unlikely to exist on a dead unterraformed world. [Answer] ## What humans need to breathe in order to survive For the first part of your question, the section of the [NASA Manned Systems Integration Standards](https://msis.jsc.nasa.gov/sections/section05.htm#_5.1_ATMOSPHERE) on atmosphere has comprehensive information on how one would go about designing an atmosphere. It is intended for use in spacecraft but it can also apply to planets, though on a planet you would have to account for gravity as the gasses will separate by density (like oil and water). The document covers: 1. Earth's atmosphere composition 2. Human performance limits, which are summarized in this chart: [![Relationship Between Percentage of Oxygen in Atmosphere of Space Vehicle and Total Pressure of that Atmosphere](https://i.stack.imgur.com/FFMq5.gif)](https://i.stack.imgur.com/FFMq5.gif) The way to read this chart is to find the pressure of your atmosphere on the left axis. Then find what percent of the atmosphere (by volume) is oxygen on the bottom axis. If the intersection of those values is in the "Unimpaired performance zone" then your people will breathe normally. Above that, the oxygen is actually toxic and may cause lung damage and eventually death if the concentration is high enough. Below that there is not enough oxygen; their judgement will be impaired and they may suffocate. Note that the acceptable percentage of oxygen changes with total atmospheric pressure. 3. A list of additional conditions that must be met for an atmosphere to be survivable. Some of these are covered by the previous chart, others include: * Pressure high enough to prevent the vaporization of body fluids * Some inert gas to prevent atelectasis, a type of lung collapse * Low flame and explosive hazard. Hydrogen reacts violently with oxygen, so it should not be in high concentration. NASA considers oxygen concentration over 30% to be a fire hazard, but this limit is arbitrary. Different materials will start reacting with oxygen at different concentrations and may spontaneously combust under the right conditions. 4. Gas compositions. The Earth's atmosphere has many different gasses, and most of them do not affect us. Like with oxygen, however, they may become toxic at certain pressures. 5. Human response to diluent gasses. I find this kind of fun, especially if you're inventing an alien atmosphere. You could use nitrogen like Earth, or you could use helium, neon, argon, krypton, xenon, or hydrogen (though hydrogen might explode). The thought of a helium-oxygen atmosphere amuses me, since it would cause everyone breathing it to speak in that hilarious squeaky voice. It might be a problem on a planet though, since gravity would cause the much lighter helium to float to the top. 6. CO2 toxicity. The short answer is, 1-1.5% is normal range. At 3% people will experience unpleasant side effects for about 3 days but will acclimate. Concentrations 10% or more can kill. Interestingly, returning to a lower CO2 environment can cause withdrawal symptoms. There is much, much more to this document, but that hits the most important parts. I suggest that anyone interested in realistic science fiction involving human spaceflight browse through it. ## What atmospheres can naturally occur on planets As for the second part of your question, I suggest you look at the atmospheres of other solid bodies in our solar system and exoplanets which we have estimated the atmospheres of. It appears that the most abundant gasses are inert, which makes sense since over millions of years the volatile gasses will react and form more stable gasses. Thus, carbon dioxide, nitrogen, and noble gasses are common, but oxygen is not; Earth has plentiful oxygen because plants produce it. Hydrogen is common because it is the most plentiful element in the universe. [Answer] The normal atmosphere is made up of about 20% oxygen, 78.1% Nitrogen, and 1% argon. Humans would flourish at a level of oxygen at or above 21 %. If the Oxygen level is below 17% you start to feel signs and symptoms of hypoxia. At 17% your night vision begins to deteriorate. 16, 15, 14% basically cause you to start seeing things, hearing things, and other physiological effects. At 6-10% you are incapacitated with sicknesses, including vomiting and nausea. If you go any lower than 6% you will be dead in minutes. [Also, a human may die if exposed to too much CO2. This is called Hypercapnia.](http://www.wikipedia.org/wiki/Hypercapnia#Causes) [This](http://www.cdc.gov/niosh/idlh/124389.html) is a link to the CDC on Carbon Dioxide. You might find it interesting, although it is too high level for me to understand easily. [This](http://www.quora.com/Prometheus-2012-movie/How-much-CO2-would-be-fatal-within-2-minutes) link has an interesting discussion on the topic of Carbon Dioxide levels, although it is not the most trustworthy site out there. I will add more information if I find any. Source(s): [Wikipedia article on Hypoxia](http://www.wikipedia.org/wiki/Hypoxia_(medical)) [Other Wikipedia articles on Hypoxia](http://www.wikipedia.org/wiki/Hypoxia) [Answer] I'm pretty sure that the only two compounds that humans rely on are oxygen and [carbon dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide). Oxygen is what the cells of the body use in chemical reactions that produce energy. The partial pressure of oxygen can vary, but the higher the pressure, the greater the chance of oxygen toxicity. Systems for supporting human breathing in extreme environments (SCUBA, space suits) mostly use nitrogen or helium as "filler" gasses depending on the pressure. ([SCUBA gas mixtures](https://en.wikipedia.org/wiki/Scuba_diving#Gas_mixtures)) Carbon dioxide is part of the process in the respiratory system for autoregulation of breathing - too little carbon dioxide and a human will not breathe often enough, while too much can cause hyperventilation, and eventually other problems. ]
[Question] [ I have a world where the magic system is based pretty much on the Ars Magica RPG and a technological level roughly equivalent to 17th century Earth. Co-existing (in the same geographical areas but not typically the same settlements) with humans and human-like beings that are approximately the same size as normal humans are fairies - who are effectively humans who average 3" / 7.63cm tall and weigh on average 0.017lb/7.5g with a variety of insect-like and bird-like wings and the ability to fly about as well as the creature their wings resemble. Through magic, these fairies: * Are as intelligent as normal-sized humans. * Have the same physical proportions as humans (making them proportionally stronger than normal humans according to the square/cube law, able to lift about 10 times their own mass on average, i.e. 75g). * Do not need fur or unusually thick clothing to retain body heat in climates comfortable to normal sized humans. * Need to consume only three times the amount of food/energy per unit mass in comparison to normal humans (roughly 9 proportionally-sized meals per day - or fewer larger meals - as opposed to 3 per day for normal humans) instead of 10 times that of normal humans as the mathematics would suggest is necessary. * Are each militarily roughly equivalent to an equivalently equipped and trained normal sized non-magical human due to their small size, quickness, proportionally greater strength and magical abilities. * Can interbreed with normal sized humans (with considerable difficulty due to the size difference), producing fertile offspring of the same size and ability to fly as the mother. * reproduce and mature at the same rate as normal sized humans. * speak and hear 2 to 3 octaves higher pitch than normal humans. Given these factors, what differences would occur in fairy society including both sociology and settlement design, in comparison to normal humans. Edit: Some misapprehension appears to have arisen over fairies' military capabilities. The average normal-sized human peasant conscript is equivalent to the average fairy peasant conscript in combat, given similar equipment. The fairy would need to get a large number of good hits on the normal-sized human to incapacitate or kill him, but the human would only need one good hit to eliminate a fairy, the size, speed and stealth factor is included in this comparison. In contrast, a trained and armoured knight (either fairy or normal-sized) could be expected to be able to cut down dozens of peasants, be they normal sized or fairy. So, given a fairy army of size N, it is considered equivalent to a normal human army of size N. Yes, there is asymmetry, however this is factored in. Finally, fairies do not reproduce any faster than normal-sized humans, so each loss is equally as significant to their society, regardless of the size of the combatant. Secondly, I didn't adequately explain that Fairies are limited in the places that they can live - they require particularly high levels of background magical aura, without which their magical advantages will be lost, i.e. they would become quite stupid (about as smart as a rat), would need to eat constantly (30 full-sized meals per day, not just 9), and would require a tropical climate or highly insulating clothes to avoid hypothermia, as well as having a much-reduced lifespan - on the order of weeks as opposed to normal humans' years (A 100-week old fairy in a non-magical environment would be positively ancient). Normal humans are not limited in this way in reverse, however given the fairies' advantages in their high-magic-aura environments, this explains the geographical separation (Magicians - fairy or normal human - cannot affect magical auras positively, only negatively, and only indirectly, by over-use of magic). So, a fairy cannot go "anywhere", only where the world is magical enough for them to exist. More magically powerful fairies can go a little further from these places without these ill-effects, but must use their personal magic to compensate for the lack of environmental magic, in turn reducing their usual magical capabilities. Regions of low magic aura are effectively barriers as much as mountains and seas are to normal humans. Finally, This question was intended to be about how these fairies would live and interact with each-other as much as how they would interact with normal-sized humans; most of the answers seem to be focusing on warfare and species domination as opposed to what this question was actually asking. So: How do these fairies live, i.e.: What would their settlements look like and what occupations would they follow? What could they trade with other races? [Answer] TL;DR: Fairy society would be very similar to human society. Fairies would be less spread out, and would travel less, and a few industries would be minorly effected by the change in size. Faries could trade with humans. Fairies would offer their magical abilities and size, and the human would trade things nort available in fairy territory. At first glance fairies and humans would have few differences. But fairy society would generally be more ingrown than human society. Fairies have very limited ability to travel outside of their homeland, which makes them more focused on their own village. While humans can cross a mountain range, or sail across a sea, few fairies can travel across non-magical areas. This means each fairy village will be more isolated than a normal human village. Fairy exiles will have less places to hide. The areas where normal fairies won't travel, also happen to be deadly to almost all fairies. Powerful fairy exiles could survive outside of the magical regions, but they would be vulnerable to unfriendly humans and other predators. Fairy occupations in their own villages would be similar humans' occupations in many ways. Although all jobs would be done on a smaller physical scale, but fairies have similar physical needs to humans. Fairies would focus more on food, because they need to grow proportionally more food to feed the same number of humans. However, food would also be easier to grow, because a grain of wheat is fairy sized. i.e. One grain can feed a lot more fairies than it can feed humans. So the food issue can be looked at from either direction. It depends on whether or not fairies use fairy sized crops. The clothing industry would be less important in fairy society, because there isn't as much need for it. Transport would be significantly less valuable, because flying is more efficient than most ground transport. However, when fairies need to transport large amounts of goods, they would likely use some form of ground transport. Fairies can't carry that much while flying. The military in fairy societies would be roughly the same as in human societies. Military tactics in battles would be significantly different, but the basic numbers and training required for a fairy army would be approximately the equal to human society. Fairy armies would also include magicians, which would allow special sneak attacks, because these magicians can leave fairy territory. Fairies could trade with humans. There is no reason fairies couldn't grow human food or create cloth human sized. It would be more difficult for fairies, but it could be done. Fairies can't get resources outside of their territory. Humans would serve to get these unavailable resources. Many luxury items would be things found only outside of the magical realms, and so they would need to be brought in by humans. Fairies may also be able to trade magical training. That is, a fairy magician can train a human to perform magic, in return for some trade goods. In addition, fairies would have an exceptional ability to fix things, because they could see them at a closer range. A fairy can fit into a pipe, or seal a small crack on a pot. Fairy strength can be focused on a very small area, making them good at fixing small and delicate things. --- Original post: * Jobs for fairies would appear. Plumbing would be revolutionized! Fairies would be able to more easily enter tight spaces, and would be better at jobs that required delicate work. Likewise, human work would be more concentrated in areas that require bigger workers. For example, humans would more likely work felling trees or digging canals. Fairies can also fly, which opens up new opportunities for transport. Groups of fairies could possible lift quite heavy things when they worked together. * Towns would adjust to have two different types of inhabitants. No doubt there would be the occasional town with just humans or just fairies. Depending on how each race viewed the other, these segregated towns may be common. But towns that do have both races would be set up differently. A fairy and a human inhabitant different levels of living space. Fairy homes could easily be built underneath or on-top of human ones, saving some expense. Stores would also need to cater to both types of customers. Most likely, stores would hire salesman of both races, each to cater to his own size. * Technology would be dual created for both races. So a plow would first be invented for, say humans, and then inventors would work on transforming it to fit fairies. * Games would be different, both children's games and "adult" games. Children would invent games that could be easily played by both races, or games where each race a particular part. Adult games, for example sports, might be specific to one race. Or the games would include roles for a specific race (fairies playing football would definitely change the game). * The military would change. Fairies would become an important part of an army, and new military tactics would emerge. Fairies would also be exceptional at reconnaissance, due to their small size and relative strength. [Answer] This postulates a being that is as capable as a human, or even more capable, in many important situations, at a fraction of the cost of energy and space. I would expect humans to play a minor role as manual workers in a society dominated by fairies. The food consumption already hints that this is going nuts: a human with 50kg has over 6000 times the weight of fairy of 7.5g. At three times the food consumption per weight, that still means one human's food can sustain over 2000 fairies! What makes matters worse is that these fairies excel at the most problematic parts of a pre-industrial society. Construction? Much easier if rooms and houses are tiny. Defense? Just fly anyone or -thing in danger up to a safe spot. Clothing? These fairies are temperature-resistant. This ability will dominate over clothing, which wouldn't work well for them anyway. Unless there's need for protection from sunburns, they'll be naked (or mostly naked) without any problems. Compare a few jobs: * Intellectual: one human scholar against 2000 that can fly anywhere to look at things. Huge counts of them could be in range to meet up and discuss on short notice, due to both high population density and fairies' mobility. * Scout: a fairy scout has increased range over bad terrain since its efficiency in transporting rations is higher (by about a factor three before taking reduced clothing into account). And again, they can fly, taking paths impossible for humans and observing from the sky. I didn't even start with the part where it's again one compared to thousands. * Soldier: The sheer count ends this battle immediately, since fairies are by definition as dangerous as a human in combat. But what does this mean in practice, in an actual war over time? They won't be fighting in symmetrical battles between soldiers. Fairies' real advantage comes from agility, stealth, range, and reconnaissance, not from who dies first in a duel. An enemy would be raided and bombarded at the worst locations, with little casualties on the fairy side. A counter-attack would find a deserted target, except maybe for a team raining projectiles on it. There just wouldn't be a fair battle in the first place. * King, or commander in general: here, numbers, cost, strength, and size are not important. What counts is the mind and the ability to receive information and convey commands. Fairy commanders are mobile. There will be occasions on which a fairy can fly from one location to the next, to look at a problem or shift focus quickly -- or to flee when cornered. Why use a human commander, when suitable candidates are rare and only bring disadvantages? I'll stop here since that is enough to determine who dominates. Maybe there will be work on farms for humans. Maybe a human is useful here or there due to size. But it is very unlikely that humans would be more than smart workhorses. ## Addendum With the edits to the question, a magical aura is introduced, which becomes a vital resource to fairies. Fairies moving out of this aura are as good as dead without help. The resulting world depends strongly on the spread and shape of this aura, as fairies would be at a grave disadvantage at practically everything when approaching its border. I would assume that symbiosis with humans becomes very important to fairies, as a human can help them overcome rifts in the aura, or save them if they end up outside of the aura for whatever reason. Thus, even if I can't "zoom in" much, I'd say that the lands far from the aura's borders would be strongly human- or fairy- dominated, depending which side they're on, while the border would be dominated by human-fairy symbiotic settlements. [Answer] Fairies become humans. The original humans go extinct. Humans and Fairies are not equal in a fight. > > Are each militarily roughly equivalent to an equivalently equipped and trained normal sized non-magical human due to their small size, quickness, proportionally greater strength and magical abilities. > > > Any fairy (are each) is as strong as a human soldier with full equipment. Guess what happens if you have trained fairies. They tear humans apart. Fairies have a greater economical efficiency. They require less space, can do more work and eat more. They're also more agile. When faced with a power that is greater in both economics and military strength, you lose unless you can find a strength of your own. But humans can't shun fairies from their society. Fairies are so small, they can live in the places where you didn't think to look. So fairies can't be wiped out, for they'll live everywhere. Humans don't have the means to detect them either. It's not possible to end up with peaceful coexistence. Not even if both sides agree to such a thing. The population limiting factor for humans is economical and medical. The economical constraint falls away for the fairies. Short of a plague, there's nothing to inhibit fairy population growth. You've made them too strong. They have magic to help them in their tasks such as moving things, cooking things... The fairy population will expand across the globe. Human territory cannot be defended and falls. Without education, you don't end up with very smart humans. You get inefficient working animals. Humans go extinct. The only thing that would stop this is if fairies agree to leave certain areas alone. Humans end up in a wildlife preserve. --- Your question boils down to "What happens if we add a" * Stronger, and * Magical, and * Equally intelligent, and * Environmentally resistant, and * Flying race of beings? Well guess what. The previously existing race disappears. [Answer] Other answers have pointed out that humans would have a hard time keeping a niche in this world. So to keep stories set in this world interesting, you might have to compromise a bit on the "intelligent as normal-sized humans" condition by giving them psychology quirks. Consider fairies in J. M. Barrie's Peter and Wendy and Disney's Disney Fairies franchise, which are a little bigger than your fairies (roughly as tall as Jonathan Swift's Lilliputians) but have the disadvantage of a one-track mind because a fairy's brain is only big enough for one emotion at once. Tinker Bell's jealousy over losing Peter to Wendy drives much of the plot. This might give humans one advantage over the fairy menace: ability to hold more than one thing in a single mind at once, as opposed to a couple dozen or hundred arguing fairies. But in a way, some humans would too develop a one-track mind, obsessing over jealousy of the magic that gives fairies an unfair advantage. This would make humans desperate to figure out the nature of magical phenomena on which fairykind relies. And with their attention span, they just might crack it. [Answer] I can't imagine it ending well. The fairies you've described have very few disadvantages compared to humans. Given that their intelligence and lifespan are the same as humans, I'd imagine that in fairly short order in a mixed settlement pretty much all of the jobs which don't require brute force or size would be held by fairies, simply because their cost of living is orders of magnitude less. Certainly clerical work and most crafts could be performed significantly more efficiently, even by whole groups of fairies. And given that fairies and humans are equals in a fight, I'd foresee a fairy-led society with humans as an underclass within a couple of generations, especially in an early modern society, which is transitioning toward industrialization. ]
[Question] [ I see that asteroid mining had already been extensively discussed in the context of today's technology (Ex. [Is Asteroid Harvesting economic?](https://worldbuilding.stackexchange.com/questions/5168/is-asteroid-harvesting-economic)) and the answer is a definitive "No" - it's not economical from Earth's perspective. But what about the future? Assuming that a number of technologies would see a breakthrough, would it make sense one day to bring materials from space back to Earth? Let's presume that we have at least the following: 1. Space elevator. Anything, including ISS-sized crafts can be lifted to geostationary orbit for a pure energy cost, and the energy can be effectively recouped when we lower the cargo down to Earth; 2. Nuclear fusion. We can equip our space facilities with energy supply that is orders of magnitude higher than today and not depend on massive arrays of solar panels; 3. Advanced robotics. All mining facilities and cargo ships can be operated by the AI; Do you think it would make sense to mine the asteroids and bring the materials back to Earth in 100-200 years? P.S. There are also some assumptions for this scenario: 1. Nuclear transmutation is still not economically viable in this time period; 2. Manufactured products are still in great (and growing) demand on Earth. We can either be bringing raw materials, or refine them in space, or build whole consumer products in space and lower them down, whatever is more economical. [Answer] Bring back to the Earth? Almost certainly not. As mentioned in the other related thread, anything you can find out there in the solar system you can also find right here on earth, and generally in vastly greater abundance and ease of retrieval, if you're comparing to the difficulties involved in getting to an asteroid and mining ore off it in a vacuum suit millions of miles from anywhere. As MrAnderson mentioned in his comment though, the cost/benefit analysis changes dramatically as soon as you start getting lots of work being done in space, because if you can get your raw materials in space, you don't have to lift it out of a gravity well. If you can manufacture your spacecraft and assorted tools and equipment and what not in orbit, you don't have to lift THOSE out of a gravity well either, so orbital manufacturing and asteroid mining go hand-in-hand in support. So, the moment you need enough of something in space that it's cheaper to launch a factory into orbit to MAKE those things, rather than launch them from the surface individually, then it'll also start to be cost-effective to support those factories with asteroid mining. [Answer] Definitely a good long term investment Space is big. [Insert H2G2 quote here.](https://www.goodreads.com/quotes/14434-space-is-big-you-just-won-t-believe-how-vastly-hugely) Moving around in space takes a lot of energy or a lot of time (as in, even more time than usual) if you're willing to use [ridiculous witchcraft gravity assists](https://en.wikipedia.org/wiki/Gravity_assist) to get that large amount of energy for free. Thus, with the perfect setup of planets, it'd be entirely possible to send automated ships to the asteroid belt with minimal amount of effort, and hopefully not moving too fast to waste energy slowing down when you get to the asteroid you want. Which is important, because you'd need it all for the return journey, as you have a lot of mass to ship back, which you will also use gravity assists. Getting your ship into space is free, since you specified that we've got an elevator to do so, and I've neglected to factor into account the cost for said elevator. Slowing the asteroids down sound tricky, but hopefully we can rendezvous a few boosters into it when it starts getting close. The problem is that using gravity assists require waiting for the planets to align, and could take a long time, take a look at the [Parker Solar Probe](https://en.wikipedia.org/wiki/Parker_Solar_Probe), for instance. So this would take a while. You could easily net [a few billion dollars](https://www.asterank.com/) off an asteroid (until everyone starts doing it and the laws of supply and demand take over, anyway), you'll just need patience. [Answer] Energy We don't really need materials on Earth, we need energy. If we can use the materials to generate energy for Earth, we solve most of our issues. Almost all of our air pollution is caused by energy production. If the energy could be created in space (e.g. beamed solar power), you cut out on almost all air pollution (put a cork in the cows for the rest). You could also use that energy to run CO2 and methane scrubbers to reverse damage. Bringing materials back to Earth would just add to physical pollution. That said, it might be worth it to bring back materials that can only be created in zero G. I have heard that "foam steel" has a very good strength to weight ratio. Also, there may be alloys that are only possible in zero G. Since substances won't separate by weight, there has been a lot of speculation about things like plastic/metal alloys. Those materials may be priceless on Earth or may just end up being a fancy way to accomplish a task that simpler and cheaper materials can accomplish. The unknown value of material goods (aside from turning scarce metals into commodities) makes the case for bringing back energy rather than physical goods much stronger. If you put the solar panels between the Earth and the Sun, you can also do a small bit for reducing solar energy that reaches the Earth (it would take a mega structure to have a significant impact). [Answer] The question is critically dependent on cost of transport. If you wrap a conventional hull around a bunch of ore, like big ore ships, the answer is "no", at least initially. Where travel on Earth is measured in distance,in space it's measured by delta-V: What tis the minimum delta-V to get something from one orbit to another. Let's consider moving water from Saturn's rings to Mars. Minimum energy orbit takes years. If you do it using rockets, you need a lot of fuel. Instead we use a rail gun. Our ice is gathered into standard 10 kg hunks, frozen, and put on a sled on the rail gun. This accelerates to to some large velocity. The sled stops, the ice keeps going. Low energy return track for the sled. Done right you have string of ice cubes a km apart moving at 30 km/s or so. Newton's laws still hold, so the rail gun is moving the other way. Half an orbit later however, it does another series to cancel the momentum change out. The over all net effect is that Saturn is boosted in a slightly higher orbit. Similar operations can be used to ship anything around the solar system where delivery time of months to years is acceptable. Depending on tech available either finished products, refined materials, or raw rock/ice can be shipped. Catching it at the other end can either be in orbit, or direct to planet surface. The latter is fine for ice cubes. Something gentler is needed for finished products. As you can imagine the costs to set up this infra-structure are -- ahem -- sky high. --- To boot strap this, we need to start with a very rugged nuclear rocket. Probably some form of gaseous uranium reactor to get to the necessary temperatures. Currently this is very future tech. The idea is that you use the reactor to boil rock, or to power a rail gun that throws gravel at VERY high speed. You land on an Near Earth Asteroid, set up the rocket, and the rocket and automated machinery hurls some few percent of the rock off at high speed, and modifies the orbit to get captured by the moon on it's next pass. Now you have a cubic km or so of mixed stone and iron to use for construction. Refining will take some more work, but very large (km scale) mirrors are easy in space. And a km of mirror is about a gigawatt. Focus that down to 30 m or so, and you can melt almost anything meltable. So is it economic? NOt with today's tech, but with reasonably foreseeable tech, I would say, yes. How long? If you have guys like Elon Musk running it, within 50 to 100 years. ]
[Question] [ Is there a way to induce a solar flare / coronal mass ejection (CME)? For instance, could a very tight glob of charged particles reconfigure the the Sun's corona leading to this type of event? Is there a precedence for this type of glob in the experimental evidence or theory? What would be the characteristics of this glob? Technology ranging from natural occurrence (a q-ball style answer -- though I doubt a q-ball could do this) up through moderate interstellar travel (the models we have on paper -- wormholes, [Alcubierre drives](https://en.wikipedia.org/wiki/Alcubierre_drive), etc.). Preference is given to natural occurrences. The upper limit is nebulous. I've seen a few questions on destroying the sun recently. I am not interested in the long term destabilizing or destruction of the Sun per se (though if this is a possible side effect please note this), just the production of flares and CMEs. [Answer] Let's first think about what causes solar flares. The processes behind them are not completely well-understood, but we do have some ideas. One possibility is [Magnetic reconnection](https://en.wikipedia.org/wiki/Magnetic_reconnection), where the magnetic field of the Sun quickly changes in shape and topology, releasing a substantial amount of energy. The result is a solar flare, a coronal mass ejection, or something similar. This sort of process is likely responsible for activity in [flare stars](https://en.wikipedia.org/wiki/Flare_star). If you want to trigger a solar flare, what do you have to do? Disrupt the Sun's magnetic field. The great bit about this strategy is that there isn't really long-lasting damage to the Sun, like there might be if you chucked another star at it (pro-tip: don't do this!). If you can, for instance, subject it to another really strong magnetic field, you just might be able to trigger reconnection. Okay, but how can we do this? The ideal source of the magnetic field is . . . * Not very massive, so you don't mess up the orbits of the planets. * Stable, so it survives the encounter without triggering some catastrophic magnetic event. * Fairly simple, if possible. This gives us several possibilities: * A magnetar. A close encounter with a [magnetar](https://en.wikipedia.org/wiki/Magnetar) - a neutron star with an extremely high magnetic field - could be a possibility. Unfortunately, neutron stars have masses about about two times that of the Sun, but if you're looking for some nice magnetic activity, a pass by a magnetar might be what you're looking for. Plus, you don't need to build anything; these are natural objects. * A gas giant. It has been hypothesized that [hot Jupiters are responsible for superflares](https://en.wikipedia.org/wiki/Superflare#Hot_Jupiters_as_an_explanation) in some Sun-like stars. The theory is that the magnetic field of a gas giant orbiting close to the star becomes entangled with the star's magnetic field. Reconnection eventually happens, giving off a huge amount of energy; superflares can have energy 1,000 to 10,000 times that of a solar flare. Star-planet magnetic interactions are actually more significant than you might expect. They can be intense enough to cause radio emission that may be detectable from Earth (see [Vedantham et al. 2020](https://ui.adsabs.harvard.edu/abs/2020NatAs.tmp...34V/abstract) and [Pope et al. 2020](https://ui.adsabs.harvard.edu/abs/2020ApJ...890L..19P/abstract) for a recent possible detection!). Another advantage of using a giant planet is that the system as a whole likely will not be catastrophically disrupted, as a magnetar encounter might. [Answer] You should look into star lifting <https://en.wikipedia.org/wiki/Star_lifting> > > The simplest system for star lifting would increase the rate of solar wind outflow by directly heating small regions of the star's atmosphere, using any of a number of different means to deliver energy such as microwave beams, lasers, or particle beams – whatever proved to be most efficient for the engineers of the system. This would produce a large and sustained eruption similar to a solar flare at the target location, feeding the solar wind. > > > The general idea here is to use orbital power satellites that collect energy from the sun, and then use (in the above case) beams of energy (particle, laser or what have you) to super heat a small section of the sun, causing a sustained solar flare like eruption. This would seem to fit you needs, perhaps this is on a bit of a grander scale, but I think anything affecting a sun sized body would have a grand scale. A few natural sources that could cause this effect would be a quasar a pulsar or a GRB (gamma ray burst) whose beam hits the sun, how realistic this is, physics wise, I don't know. But we need a beam of high energy for the above example and well.... it may not be entirely unbelievable. I've seen stranger things in movies, like mini-guns on asteroid mining rigs. [Answer] # You need to decrease the temperature of the corona A [solar flare](https://en.wikipedia.org/wiki/Solar_flare) is caused by magnetic reconnection (probably; I will assume this is true for the rest of this answer). A series of magnetic loops near each other will reconnect with each other in a different topology. Since highly energetic charged particles tend to follow the loops, this reconnection can orphan portions of the magnetic lines of force. These unconnected magnetic helical fields and the charged particles tracing them can then explode outwards in a flare. [Magnetic reconnetion](https://en.wikipedia.org/wiki/Magnetic_reconnection) occurs when two (or more) magnetic field lines approach each other. The plasma's electrical resistivity in the boundary region opposes the currents that should be formed by the two fields. This opposition forms a 'potential gap' of sorts, acting in a way like a magnetic capacitor (please don't quote me on that to a physics professor). This is the mechanism that stores up energy. Once the magnetic lines do reconnect, this energy can be dissipated into the 'orphaned' charged particles, giving them their motive force. Since magnetic reconnection is associated with higher electrical resistivity, in order to induce flares, we want to raise the [electrical resistivity](https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity). Resistivity is the inverse of conductivity. Figure 2 here shows that electrical conductivity increases with increasing temperature (up to 30,000 K at least...). Therefore, electrical resistivity decreases with \_increasing temperature. Therefore, anyone saying to hit the sun with a lot of energy to cause a solar flare is probably wrong. You want to decrease the energy in the sun's corona along the magnetic field lines. This will lead to more stored energy that can be released by magnetic reconnection. How to decrease the temperature of the corona? Frankly I have no idea, not even in far out sci-fi terms. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 1 year ago. [Improve this question](/posts/74622/edit) 3/19/2022 CIA official briefing, EXTREMELY URGENT --- Mr. President, Over the past several weeks, it has come to the attention of the CIA and several other global intelligence agencies that certain individuals have been displaying inexplicable paranormal abilities. Observing these individuals has yielded interesting results. Many of them appear to be as confused as we are, having only just discovered their abilities. A few say they have had these abilities for as long as a half a year, and have honed them through trial and error. There is a third group. At least half a dozen of the observed claim to have had their abilities for longer. Substantially longer, in fact. The oldest among them maintains that he was worshiped as a god in Ancient Mesopotamia. While we have been unable to evaluate the truth of their claims, their abilities are indisputable, and are of such a nature that some at the Agency have taken to calling it 'magic'. The Affected vary widely in ability type and strength. Observations and interviews reveal that there is some kind of semi-hard limit on the strength. Most Affected are relatively weak, even given a great deal of practice and knowledge. One common trait to the weaker Affected is that they tire quickly. One subject quickly knocked herself unconscious due to the strain of lifting a SWAT team van for several seconds. Another (in an attempt to evade a capture team) held the shape of a small dog for a full minute. A third nearly convinced one of our operatives to shoot himself before tiring. This reflects the power level of the middle 30% of Affected we observed. The abilities of the Affected are channeled through either: a. verbal commands (the most popular option, do not resemble any known language and are rarely shared between Affected), b. hand gestures (occasionally used in addition to verbal commands, not necessarily hands), or c. written runes. Denied of these, the Affected find it difficult if not impossible to use their abilities. While the most powerful Affected are not necessarily ancient, the ancient Affected all appear to be extremely powerful. All attempts to capture the ancient Affected were terminated with laughable (occasionally contemptuous) ease. We were only able to interview two of them, who volunteered. If they are to be believed, magic was intentionally eliminated from the world roughly three thousand years ago. The Affected who survived either went dormant or had previously altered themselves to become immortal. One of the ancient interviewees spoke very poor English and was having significant difficulty adapting to the modern world. Since 'magic' has returned to this world very recently (at most a year ago), few organizations of Affected have been able to form. The most common form of organization is created when a small group of very confused Affected seek each other out over the internet and begin to trade discoveries. Other organizations we have observed include: a. 'the Keepers', a group of several dozen moderately accomplished Affected who seek out lost artifacts from the ancient age of magic, and b. an as yet nameless group of Affected environmentalists who use their abilities to replenish natural areas. We note with some distress that the Mafia and the Zetas drug cartel have begun to develop sub-organizations of the Affected. Finally, a note on the abilities we have observed more than once: Precognition, teleportation, shapeshifting, mind control, healing, gravity manipulation, telekinesis, transmutation, and memory erasure. Mr. President, what the hell do we do about this? Do we alert the public? start a witch hunt (no pun intended)? The CIA awaits your instruction. --- When answering, please state your intention before your course of action. Bonus points if you can answer from the perspective of multiple world leaders. #Resurgence [Answer] Mr. Director, First of all: Regardless of whatever strange abilities they may possess, those who are American citizens are to be given their full rights as American citizens. If they have committed crimes, they should be arrested (if possible) and given due process. If they have not committed crimes, they are not to be harassed. While I appreciate the enhanced security risk that rogue "magic" users pose, a blanket policy of detaining everybody with these abilities is both illegal and un-American. I expect your agents to follow this order effective immediately. Furthermore, I am instructing all U.S. intelligence agencies and all branches of the military to begin an active recruitment campaign among these individuals. As with any pool of talent, the more of them we have on our side, the better. We need to recruit them before criminal organizations or foreign powers do. You will, of course, conduct especially thorough investigations into recruits' backgrounds and other ties before granting security clearances. I want a full report on the numbers and relative strength of these individuals in other countries, how other governments are reacting, and the degree to which criminal organizations' recruitment efforts are succeeding. Continue monitoring any online communities to the fullest legal extent, so that we can be aware of any hostile groups taking shape. Finally, be especially careful dealing with the highly powerful individuals. I am disturbed that attempts have been made to capture some of them, no doubt provoking fear and animosity toward the U.S. government. Your agents are henceforth to take a conciliatory approach at all times, unless to do so would endanger the lives of civilians. We do not need such powerful people as enemies. If they wish to be left alone, and if they are not harming anyone, leave them alone. At the same time, continue your efforts to establish friendly communication and learn more about this phenomenon. You have my authorization to extend the aid of the U.S. government (including English lessons and job training) to any "ancient" individuals who need help assimilating into American society. (There is no need to announce anything to the public; due to this morning's incident in San Antonio, all major news networks are running a lead story on the phenomenon as I write this. My aides tell me that #magicisreal has become a trending topic on Twitter. I will be taking a call from our NATO allies this evening to discuss the matter. Depending on public reaction, I may address the nation within the next few days. We must live up to America's reputation by reacting in a spirit of welcome, not of fear.) President \_\_\_\_\_\_\_\_\_ The White House March 19, 2022 [Answer] Reallisticaly? We must gather them all and study their superpowers! Specifically, we MUST do it before someone else can. Let's invest half of our budget for pensions, education and healthcare just to fund a new investigation section of DARPA to deal with these subjects - we'll deal with the protests later, invent a new enemy or start a war, I'll think about it after lunch. The "Affected" must be located and caged a.s.a.p. and studies on their abilities should commence immediately. Our first priority would be weaponizable abilities, and mind control or memory erasure - this one would be of great use against the press and civil rights lawyers, since we officially don't support this nor do that kind of things to our people. Strategies and plans to deal with the ancients must be prepared and deployed immediately. If they are too powerful to be confronted, we will be forced to kill them from beyond visual range while reducing collateral damage as much as possible. The acquisition of these new capabilities for our country should take precedence over any other considerations. [Answer] Tldr: I feel the question is a bit vague if it doesn't mention their exact superpowers. Understanding their powers and intentions is the first rational objective that comes to mind. Firstly we have to determine what the Affected want. If they just have ordinary human desires and want to lead a life within current rules, then it makes sense to make allies with them as soon as possible. If possible, they will have to be surveiled and studied, before contact is made. They will be granted asylum in our country if they are willing to go through a series of physical and psychological tests that will establish trust between us and assure us that the Affected will not break our law. If they want any modifications to the law, or any other requests, they may do so. Of we feel they are particularly threatening, we may have to carefully make requests in these contracts as well as establish working fail-safes. If however, some of them do wish to actively break current rules or ally with organisations working against our country, or else participate in any activity that we deem harmful to us or to their minds, then we will have to take a cautious stand on the same. We could end up with anything from a new international cold war to an Affected issuing ultimatums to the globe, etc. etc. It will be best to make our intentions clear to them to avoid such a situation. Actions will be taken largely on the basis of intel gathered, whether it is new contracts or a quarantine or even an elimination of an Affected. Action will depend on the nature of the threats they possess and the abilities we know they possess. It would be unwise to engage in combat without knowing their abilities. Some sacrifices might have to be made for the larger good, both on our part as on theirs. [Answer] CIA: take this course of action immediately, find and contain all of the Affected, we will build a large compound, maybe in Russia or Canada, those huge empty places and with the help of governments around the world we will restrain the Affected. The only hard part are the ancient Affected, but they're good at being quiet. The only thing we really don't want is a witch hunt, it'll ruin modern day society. Sincerely Mr. President. [Answer] Mr. Director I regret to inform you that I, the new leader of the Grand Old Party, have overthrown president DLosc due to excessive woke-ness in dealing with this new threat. You now answer to me; if you are unhappy about this, I'll happily accept your resignation. Those orders you recieved yesterday? Toss them in the trash. Your new orders are to round up all of these witches and warlocks, the only exception being those in the top 0.1%. Those plutocrats work hard to keep america turning and put a stop to socialism, we are NOT going to let these socialist magic-users take away their hard-earned right to their piles of gold. If anyone objects to this, lock them up too. Oh, and those 'powerful' magic users? Use any means at your disposal to kill them, nukes included. It is better to murder 5 million innocents than let a single socialist go free. -(insert bigoted conservative wannabe-tyrants' name here) ]
[Question] [ Like [this question](https://worldbuilding.stackexchange.com/questions/27618/what-are-some-major-architectural-designs-that-would-be-in-spaceships-for-flight) I'm wondering about design considerations for an intelligent aquatic species that wants to travel into space. Would they have to try and create special body suits to keep moisture content or try and fill a ship with water? Or would they have to fill up a ship once it's in space (say a space station) with multiple trips? Size of the Ship: I am more interested in medium to larger size ships, but ones without 'Gravity fields'. Known gravity generation only. ie spinning a ship. Maybe start with something like the [ISS](http://www.nasa.gov/mission_pages/station/main/index.html). And going larger from there. What are things to that would go into the design? Here's a picture from Harry Potter's Merpeople for an idea of physical characteristics ie, tail, no legs. [![enter image description here](https://i.stack.imgur.com/Z5oY0.jpg)](https://i.stack.imgur.com/Z5oY0.jpg) [Answer] Basically, forget "down". An aquatic species would need that even less than humans do. Most sci-fi ships have floors and are arranged into decks similar to naval vessels. An aquatic species would have little need of a floor, as they can float anywhere they need to be within the ship without anything to stand on or grab onto. Now, Earth fish have a swim bladder, helping to provide neutral buoyancy, and in most fish the arrangement is most stable when there's a gravitational force on the fish, with the result that fish in zero-G tend to look uncoordinated and disoriented. We've done similar experiments with many other animals, including birds and cats on "vomit comets" for short periods of weightlessness, and the results are similar; zero-G is a very novel experience, and most animals don't know how to function without a downward force acting on them. Humans are similar in this regard, but we have advantages of sentience; we can understand what we're about to do so it isn't a surprise like it is for a cat or a bird, and we can be taught to maneuver in zero-G without having to learn it from scratch. A sentient aquatic species, theoretically, would have a similar ability to "groupthink" and thus reduce the difficulties any individuals might have. As far as the ship design, the biggest hurdle is going to be getting water out of the planet's gravity well. The Tsiolkovsky rocket equation models a fundamental truth of rockets; they have to lift their own fuel, at least what they haven't burned yet. As a result, achieving escape velocity from an Earth-like gravity well requires the rocket to be much, much more fuel than payload. "Payload" here is basically anything that isn't fuel, including the cargo vehicle but also the non-fuel part of the rocket system like its fuel tanks, pumps, exterior sheathing, nozzles, etc., which increases as the amount of fuel does, thus requiring either even more fuel or less "useful payload", what you actually want to put in space. Our engineers, therefore, endeavor to make everything they put into space as light as it can be, especially those parts of the vehicle that are disposable and used only to house the components of the rocket itself. We also figured out multi-stage rocketry; when the fuel in a stage is gone, you can lose the containment for that stage and save that weight on the next leg. Practically every manned spacecraft was launched on a multi-stage rocket, it's just been the only technically feasible way to do it. As one example, the Space Shuttle, one of the most effective launch vehicle designs in human history, used an orbiter that weighed 100 tonnes (100,000 kg). Inside that orbiter, another 30 tonnes, max, could hitch a ride to LEO. The total maximum launchpad mass of the STS, including the external tank and boosters, was 2,000 tonnes. That means that using the Shuttle to get 30 tonnes of stuff into orbit that you plan on leaving there requires a system that is 98.5% "unusable payload". Even considering the orbiter vehicle itself as "useful payload", being the quarters for the crew and a good place to conduct zero-G experiments before the ISS was finished, the total launch vehicle is 93.5% fuel and fuel containment. One last thing is shock dissipation. Water is classically an incompressible medium (theoretically its density can be changed with pressure, but the ratio of force to change in volume is many orders of magnitude more than for a gas). This is typically bad news for aquatic beings when a strong force changes the water pressure significantly. "Shooting fish in a barrel" turns out to be really easy, because the shock of the bullet entering the water is enough to stun or kill the fish swimming in it, similar to the effect of a flashbang in air; you don't have to hit them with the bullet (and in fact the bullet will slow to nonlethal velocity in the span of a few feet). [Answer] I think it would take extraordinary circumstances for an aquatic species to be capable of getting to space in the first place. Unless they are amphibious, they will have enormous mobility challenges outside of a water environment. It’s also unlikely that they would try to develop technology to mitigate that disadvantage unless their planet actually had land to explore. Even further, if we suppose that they develop sophisticated water suits capable of non-aquatic movement, that indicates that they would be inside of a spaceship that’s not totally filled with water. This would be a very difficult construction task for a species of this nature. Their technology is also very likely to be based on fluidics. Attempting to build a spacecraft with fluidics would be hugely challenging even before considering the weight that needs to be carried into space. Discovery and advanced development of electricity would be a tall order for an aquatic species. It’s tempting to instead imagine them launching a capsule full of water, but the necessity of EVAs (even if only in emergencies) will require the development of sophisticated suits anyway. With these ideas in hand, it seems that their best chance of being in space (however slim it may be) is with complex suits that have been through an extensive period of use, testing, and refinement on their own planet. These should provide them with the necessary mobility and life support to move outside of water and prevents needing to haul a full wet habitat with them. For longer stays, it will become necessary (if for no other reason than their mental health) to fill at least some portion of the spacecraft or station with water. Getting to water in space will be difficult until they have long-term and highly maneuverable spacecraft available, which means they’ll need to haul the water up there over multiple trips. Once their ships are more mobile and self-sustaining, they can begin to fill larger and larger portions with water found in space. It’s likely that the water-filled sections would start with their sleeping quarters and eventually full habitat. Airlocks of some kind will be needed when moving between habitat and the rest of the ship, but it may be advantageous to keep the rest of the interior a vacuum, thereby reducing the complexity of airlocks to space. They do have an advantage, however, in that they won’t need artificial gravity in space. As a final thought that’s slightly off topic, I also wonder if an aquatic species would even have interest in the stars. Human beings have evolved while looking upward because we could see a vast unknown that seemed just out of reach. An aquatic species might instead evolve while looking downward — down into the uncharted depths where pressure prevents them from wandering. [Answer] All the same concerns you would have with an aquarium, oxygen,temperature, and sanitation being the main ones. I would think this might mean that the entire ship might have current, and the creatures might think about the ship directions in terms of upstream and downstream. They also might be unlikely to consider landing on planets at all. [Answer] The most confortable thing would be filling with water, however unlike filling a ship with air, filling with a liquid would add huge amount of weight to the ship. The extra weight would make it very expensive to make a spacecraft to reach orbit or other planets. I think unless the aliens are very small animals , some type of body suits with portable water tanks and some type of water treatment to make the suit as autonomous as possible would be a possible compromise. Maybe a mix some small liquid filled rooms for some activities, and suits for moving around in a larger ship. Most likely large leisure spaces in the station would be too expensive to fill with water. [Answer] For a sufficiently (ie. much beyond humans) advanced aquatic species, you would not need to build a ship at all. Saturn's icy moon Mimas has a density of 1.15 g/cm^3, whereas water is 1 g/cm^3...so Mimas is almost all water. It has a mass of 3.75x10^19 kg. Supposing an aquatic species launched a robotic mission to grab Mimas out of orbit and move it nearer to the sun. As it melted it would remain a sphere of mostly water with some other heavier elements mixed it. It would, in effect, be a perfect spaceship, simulating a 3-d ocean but with much less gravity (.006g in the case of Mimas, at the surface). Any technology developed for use the aquatic species home oceans should work just great in their new space-sphere. The aquatic species could then insert themselves into this new space habitat and use it as a space station, or build an interstellar drive into it and go explore the stars. A big advantage of a liquid water sphere moving at thousands of kilometers/s would be excellent for absorbing the impact of random space particles and radiation, protecting the inhabitants much better than a human style spaceship with no energy expenditure on shields. A big disadvantage is that you can't accelerate faster than the acceleration due to gravity of the sphere or you will defrom the vessel to the point of splitting. So its slow moving. Obviously, Mimas is huge, but there are smaller comets around and one of them might be a better option. [Answer] Radiation shielding. There are potential benefits to an aquatic species in spaceship design as well. For one thing, water happens to be very good at insulating against radiation, which could remove one factor that we have to face when designing any space craft designed for long term use. At a minimum, you would want to have a "layer" of "water rooms" around the outside circumference of the vessel just to be a useful radiation block for the lighter weight central parts. Aquatic species like this would have had to create space suits for themselves long before they ever got into space, just to operate on dry land. If they existed in environments that had a higher pressure than the surface, these suits might also have to artificially "squeeze" them to keep all their organs in the right place in low-pressure environments like the surface. If they had gills, they could rely on a small amount of water in a recirculating purifier/oxygenation system (like a reverse SCUBA tank) that could be carried, so the entire ship would not have to be full of water necessarily. Alternately, if they didn't have the pressure restriction, they might fill their ship with a mixture of water vapor and some kind of lightweight, stable gas at the minimum % of water they needed to survive. Second advantage of water on space ships: Reaction Mass. Water happens to be one of the most efficient sources of reaction mass available to move a ship in a space environment. Not only that, but there is a lot of water available in space in the form of ice (mostly in asteroid belts). A ship could be designed to take on ice from wherever it could, melt it, integrate it into it's internal water system, and use it as reaction mass by pumping some of it through a nuclear-heated rocket type system or whatever else makes sense for the technology level. Instead of both a lot of fuel and a life support system, the life support and fuel systems would be basically integrated, potentially saving complexity and space. Obviously, if you use up too much water, you could run out, but everyone knows space travel is dangerous, aquatic or not. ]
[Question] [ Inspired by [this story](http://slatestarcodex.com/2015/06/02/and-i-show-you-how-deep-the-rabbit-hole-goes/), I started thinking. Let's say we have a person, from the modern day, who miraculously gets a superpower: He can rewind time, but retain his own memories. He can rewind all the way back to his birth, and can even rewind if he is dead. Otherwise, however, he is unexceptional for a human. Mostly, he won't live longer than a human could (though he won't have any chance of dying early, since he can rewind). Being tired of living out the same major events over and over, and being unable to really die (after he does, it's basically blank nothingness except for an annoying popup window that just says "Would you like to rewind?" that reopens when he closes it), he decides he wants a change of scenery. Ultimately, he decides that exploring space would be cool. But after thinking about it (or maybe trying it a few times), realizes that even if he advances human knowledge to get to cool Sci-Fi stuff, he'll still be stuck by what he can accomplish in his lifetime. So, he instead turns his efforts to curing aging, so he ("and everyone else too, I guess"), doesn't have to work his butt off to get Sci-Fi stuff to a worthwhile level. But, after learning about the topic, he realizes that the cure for aging isn’t easily obtainable. While some techniques in the modern age could extend his life to around 150 years at max, a full-blown cure for aging would take a tech level that he (as an expert in this (as well as everything, eventually)) estimates is 300 years in the future. Or at least it would be, if normal people were working on it. So, he wants to accelerate development on this topic in order to reach the goal before his death. Preferably sooner, as medicine that reverses aging seems to be around 500 years away, and he’d rather not spend 200 years as a 135 year old man (though if that’s the only way, he won’t knock it). Since he can only bring back knowledge, not infrastructure, or experimental results, or scientific consensus, he’s in a somewhat similar position to someone who just came up with a brilliant idea. Perhaps the most brilliant idea. So, the question is: Could someone who just happens to come up with a brilliant idea advance science by decades, or even centuries? Or is that just not how it works? Support for one’s answer could include examples of ideas discovered by chance that, had they not been, would have prevented us from making progress for a significant amount of time. Or, on the other side, showing that discoveries tend to require previous discoveries to work (e.g. If you have Theory A, it wouldn’t make sense if you brought it back to before Theory B, which it was based on, which itself couldn’t be brought back before Theory C, etc. And you couldn’t just introduce them days after each other for whatever reason.) Solid reasoning could also constitute evidence. For example I think answering a question like “How much of science is thinking vs. doing?” would, while not answering the question per se, get well on the way to a good answer. [Answer] Your time traveler has the advantage of being able to footprint the future by mapping out who he needs to meet, what he needs to invest in, etc. This is actually way more powerful than just coming back once with a good understanding of the tech. By the time he's in his mid-20s, he could already be a billionaire by ripping off ideas that major tech companies have not come up with yet like Amazon or Facebook and grow them much faster than they did in our world because he creates them with full knowledge of how to monetize them, and who he needs to hire to manage them so that he does not to to put much time into it. So, then he'd have a good 60+ years to rapidly build well financed Research and Development teams of people he's already spent lifetimes vetting. Then he spends his days dropping in on these teams introducing the exact ideas they need when they need them. This way, it's not just one idea to flourish, but he's eventually developing dozens of simultaneous super technologies. Each time he rebuilds his company, he comes back with new ideas that they were able to develop more quickly with his last iteration of leadership allowing him to preempt even more technologies with even more development teams for every generation moving forward. As for infrastructure and engineering he could take shortcuts here to. He might begin work on a factory for making things that seem relatively useless in 2010 that he can then slightly tweak in 2020 just as it's almost done being built so that he can make a critical component in warp drives as soon as the right nano-materials are finished being developed. Basically, skipping the wait time on getting from idea to production It might take him centuries, or even millina of starting over, but eventually, he could probably hit space flight within a few decades even if it would take us centuries to get there as is. [Answer] There is a reason that we talk about research and development as separate things. Research is about extending the theoretical bounds of science; without the Maxwell equations for instance, no-one would EVER have been able to build a functioning radio system, whether they wanted to or not. Development on the other hand is more like engineering. It's about the operationalisation and application of what we already know. Science is full of great ideas that have been found by accident. Dunlop (for example had been working on ways to make rubber tougher for years before accidentally spilling sulphur into some boiling rubber and inventing vulcanisation. Superconductors were allegedly discovered when a kid misread a science experiment instructions in a uni and put in 10.000 times too much catalyst. Most engineering problems can be solved with time and effort; theory on the other hand requires inspiration. So the answer is that good ideas can extend science in different ways to be sure, but you actually want good ideas AND good engineers who know what to do with them to extend your scientific knowledge. [Answer] # Alan Turing This generally doesn't happen, but sometimes someone with the right idea and the right technology at the right time can have a huge impact. One example of this is Alan Turing. To be fair, other people were also working on computer-like things at the time, and he could draw from existing work on logic circuits. However, without all that, it's reasonable to think that one person in the mid-20th century would have thought to create complex and re-programmable electric logic circuits (computers). So, while Turing didn't work alone, in theory someone like him could maybe have, as the building blocks were all there. Now, one could argue that the Computer is an advance in engineering, not science, but it has allowed for MASSIVE improvements in science in almost all fields. It's hard to imagine how many decades behind we would be today without the computer (or decades ahead, since no Facebook/Worldbuilding Stack Exchange to distract us...). [Answer] The vast majority of scientific advancements, whether theoretical or practical, tend to be inevitable. Generally the conditions are right, and the "genius" that invents or discovers something usually just happens to be the first one to put the pieces together. If Newton hadn't developed Newtonian Mechanics, someone else soon would have. The detailed observations of planetary motion, and the ability to measure time and mass, were advancing rapidly. It was simply a matter of putting the pieces together, discovering the patterns, and making sense of them. Similarly if Newton hadn't invented calculus in order to perform the required mathematics, someone else soon would have (and there's reason to believe others actually did). Special Relativity required Einstein's genius, but had he not proposed it, it wouldn't have been long before someone else put together the same information and unanswered questions and derived the same solution. Genetic inheritance, the periodic table, aircraft, spacecraft, etc. are all incredible achievements, but I can't imagine any of them being delayed by more than a few years if they hadn't been discovered or developed when they were. People like Edison were well aware of this, and so he ran a factory full of inventors trying to stay at the head of the wave, discovering things before anyone else did. --- In your situation, it won't be so easy. Almost any invention, theory, discovery, etc. that you introduce won't end up in a receptive environment. People simply won't accept it as anything other than the rambling of a mad man. No one would have listened to Einstein's nonsense a hundred years earlier. Introduce the germ theory of disease five hundred years ago, then suggest that people practice common hygiene and wash their hands, and you'll be accused of Judaizing. --- Occasionally there actually are new discoveries that make people say "Why didn't anyone think of that decades ago?". And for a few of those discoveries, it really was possible for them to have happened decades ago. These instances are very few and very far between. But that is the type of advancement that you are going to have to find. [Answer] I would say generally it is not how it works, even if there are examples of such history-changing technologies - bronze, iron, steam, metric system(standardization concept in general), transistors, lasers, personal computers. There are technologies which deeply affected consequent events. So as there are plenty of examples of stuff which was discovered randomly, so it possible to speed up certain things as part of the main goal accelerate technologies or getting the upper hand in competition to obtain resources and be able to focus them on some goal, in a similar way mentioned in Nosajimiki answer. Generally, technology and the ability to do a thing is interconnected, it is a result of being able to do many different things, so as ideas have to come in the right time at the right tech level. An example handwriting input [Apple Newton](https://en.wikipedia.org/wiki/Apple_Newton) good idea but software and hardware was not up to the task. Same as today deep learning is a significant topic, but it would not do that much in the 90's as hardware was not up to the task, and advances on hardware tied to many other advances and specifics of technologies. And even if one would know and be able to remember all those aspects(and it really connected not only with the process themselves, but with other processes which produce production equipment you need for your process, and those other processes also may require advances in other production equipment .... Is there or isn't there a way to achieve the goal of the character depends on the place where he is in the timeline. Is there a chance for him in the stone age to progress to the first PC in 100 years - I would say rather no, one of the big reasons he can't do everything required all by himself, so even if he has perfect knowledge he needs to teach others to do certain stuff he needs to do, and it creates a lot of problems. Can we imagine some knowledge body carried by one human which allows him to jump from stone age to space exploration immortality - I would say yes, we could imagine such knowledge - but the problem of the guy is how far he is initially from it but it is not the only problem in the case. It can be imagined like a road, with some boulders/rocks on it (which may represent some key achievements, a bit more complex than that - achievements and the plan to reach it and next rock in a certain time frame from certain starting position(which is a constant in our case, which makes it harder)) and a condition that you need to jump from one rock to another to move to the goal - some gaps may be too big for one jump(it is the time frame of the guys existance). So, in general, it is the question, is there a path on the road(or better to say a field of rocks) - such so that one can jump from one rock to another and after a certain finite number of jumps reach the goal place. It some sort of traveling not a fully interconnected graph, which structure is defined by starting conditions and by some virtual technology tree(sort of The Library of Babel of technologies). And even if we can imagine a technology which may be implemented with a small workforce(number of people), it may be like an island in the possible routes, an island to which there is no path, even if we can see it we not necessarily can reach it in given conditions. Stone age is easy to demonstrate the complexity of jump, but at the same time if we look at it from our current time, biological components/technologies may be a way to reach the goal - microbiology may produce a lot of chemicals, and mutations are a potential tool so as a selection of strains of bacterias/cells/whatever may give you materials which one typically associate with our current time like plastic [strains of bacteria that are able to produce plastic](https://inhabitat.com/scientists-develop-plastic-producing-bacteria/): * Scientists at Genomatica Inc. recently announced that they have developed strains of bacteria that are able to produce plastic without the use of oil or natural gas. The sustainable process utilizes little more than sugar and water to produce butanediol (BDO), which can be manufactured into everything from plastics and fibers to pharmaceuticals. Or another one, maybe it harder to track any connection with the topic here, but it is interesting in terms of it can be another chemistry tool, [April 2017 scientists discovered that octopuses, along with some squid and cuttlefish species, routinely edit their RNA (ribonucleic acid) sequences to adapt to their environment.](https://www.sciencealert.com/it-s-official-octopus-and-squid-evolution-is-weirder-than-we-could-have-ever-imagined): For a guy living events over and over and being able to experiment with the environment and those events, it isn't that impossible to come to an idea of small creatures living unobserved, and observing them took efforts of certain individuals which technologically were simple enough. Genetics is quite a jump, so as chemistry and the whole idea that those microorganisms can be used for some useful goals. But it is a powerful tool once one realizes it, with interesting potential, and which can produce a useful combination even if you do not know about its existence before. it just to show that stone age guy, in theory, has a chance too, but it very unlikely and to meaningfully propel to idea of plastic it needs to know the past of our time which is out of reach of the guy. As for 2000's it is a good time for your goal to be. Distances between individual rocks are smaller(in some sense), but it more of those and they have to come in the right sequence and it really a lot of them (deep recurrence, much deeper than it was for old days) and there a lot of information to carry in memory to make next iterations possible. But it is helpful that there plenty of people and there is a well-established system which helps to focus efforts in a certain direction, so as relatively developed information processing, which may be helpful to carry information back as an example. As an example - there probably is some algorithm of pseudo-random number generator(idk couped with some markov chain type stuff), which is short enough and which has relatively short seed to remember and which produces a replica of encyclopedia of Britannica(in random order, or maybe even consequent(but it less probable)), or a description of how to build a warp drive, or something more useful at current interation of the character. 2000's are good as it was a time of many opportunities created by a rapid development of technologies in a short time and at a good pace and I would say to the guy - well done well done # What kind of technologies it could be as of today * as story plot it is your choice of course, but I would say that most of the job is done by the time In terms of achieving goals today is a good day for that, it possible to argue that we have everything we need for our next big jump in time and technologies. SpaceX started as a mariachi band in 2002, now for quite some time, it delivers payloads in space and ready to deliver humans in space. And it has, theoretically, the capacity to deliver payloads on the moon. With the moon situation, we have an interesting direction of [Affordable, Rapid Bootstrapping of the Space Industry and Solar System Civilization](https://arxiv.org/abs/1612.03238) which can be coupled with [Realistic cost and feasibility of sun-shading?](https://space.stackexchange.com/a/34689/3039) as mean to face global warming which may lead to implementing solutions like that [ServerSky](http://server-sky.com/) (and not necessarily just stop at 2%, go K1) Whis wich generative algorithm and software and general digitizing of researching for materials and solution may lead to burst in our knowledge of technological and biological nature using those space resources and computations. Which if it does not solve the problem by itself, in the required time frame, which I doubt, may lead to sophisticated technologies like smart matter [there some bits on that regard](https://im42group.wordpress.com/tag/smartmatter/) mostly as potential scale of the possibility provided by smart matter or it can be any gray goo of a flavor you like. And gray goo type thing is probably suitable to be produced by means of tools we have today, but we are just lack of knowhows in that regard. And that allows you to go to K2 with from the same position as it was K1 here in the same period of time or shorter and it's a maximum power in terms of applying generative algorithms to the problems which the character is worried about and are maximum probabilities in solving them in the given time frame. (and I would say it easily can be done if the character covers only 2000-2100, so as I would argue that he could do that in 2000-2060) Quantum computing seems another technology which we sort of close and able to do but lack knowledge of how exactly. Considering all those metamaterial discoveries which potentially can be used in theory for those etc - so it may be some right combination of specific knowledge. And QC it can be quite powerful to produce new knowledge (generative designs and all that again) [Answer] I think Nosajimiki mostly has the right idea but the wrong idea of scale. It's going to take longer and involve more technologies and be far more complicated. At the "start", this person's activities amount to leading down pathways that seem like they will be productive, and jumping back to correct things over and over again. Start is in quotes, because they'll be doing complete do-overs multiple times, because there are only certain things that people will accept from 3 year-olds, and getting that right start will be tricky. Also, as they progress in this effort, they will identify individuals who will be important for them to recruit or direct earlier. Because they are only one person, recruiting the right other people will be fundamentally important. Some of these people will be important because of their own potential, which this character will want to maximize, minimize, or redirect. They will be a big asset, because each time the character goes back over previously established efforts, they will need to be careful about remembering what they did right - but a correct person placement doesn't require remembering all of the things that person needs to do. Others will be important because in real life, people don't look too fondly on the one guy who gets everything right. While the amount they can bring back each trip is limited, most of what they will be bringing back are new concepts of how to proceed, and there will be far too many of them for one person to run down. The right people to take these ideas and run with them are a bit tricky to locate. They're very clever people, but they're not necessarily imaginative. They can make engineering refinements very well, even though they lack the ability to come up with a major good thing on their own (or maybe the hero just wants to give them the idea they'd get later earlier). However, they cannot attribute all of the ideas he gives them to him, or else he sticks out too much. He'll probably be able to find a few trusted confidants who are willing to keep his super-duper-genius secret that he can work more directly with. But he'll probably have difficulty finding enough of them, so will need to find people he can strategically "steal" some of his ideas and make them work. Note that his earliest efforts would need to be getting his family to be more fiscally affluent and seeding ideas to people receptive enough to the idea of genius babies to take his ideas and running with them. If his starting point is post-Internet, he may be able to avoid the baby stigma, but until he has family resources to use, giving people ideas will be his most effective method of invoking change. There's also an aspect of fostering competition. This is probably something that he'd mostly be willing to do with the people he surreptitiously gave technology to - give it to more people. That might seem like it's less efficient, but it's laying the groundwork for more advances. And he'll need to do a lot of that, because technology has a difficult time taking root unless there is at least a critical mass of interest in it. He's also going to need to enact major school reform, and that will only be something that will be well received once it's clear that he's broken Moore's law the other way, and the world is having singularity-level technology explosions. I think school reform is actually going to be one of the most major things he needs to achieve. Someone who graduated from college in 1990 and then woke up the next day in 2010 would have a difficult time coping, but assuming nobody had an issue with their missing 20 years, I think it's conceivable that they could cope. They'd need to be a major self-starter in order to catch up, but it could be doable. But that kind of a paradigm shift would be the experience of every college graduate, if someone were advancing technology like this guy would be doing. Grant reform is, of course, another major task. But after taking over the stock market in grade school, that would kind of be his thing to do. ]
[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. EDIT *Why this is* a world-building query*. If I had framed this as, "In my world where magic requires the expenditure of energy, a powerful wizard decides to open a path through a large lake,etc. The world I am supposing is that God himself can create and destroy energy (or has an infinite supply) but still uses* energy to do his miracles and acts of creation. This is different from simply magicking things in and out of existence as the Bible perhaps implies. --- > > The Red Sea has a surface area of roughly 438,000 km2 (169,100 > mi2),[1](https://i.stack.imgur.com/z1mM3.png) is about 2250 km (1398 mi) long and, at its widest point, > 355 km (220.6 mi) wide. It has a maximum depth of 3,040 m (9,970 ft) > in the central Suakin Trough,[3] and an average depth of 490 m (1,608 > ft). > > > [![enter image description here](https://i.stack.imgur.com/z1mM3.png)](https://i.stack.imgur.com/z1mM3.png) Assumptions for the purposes of this question We cross where the sea is 100km wide, the depth is 500m at its maximum, the seabed is an arc of a circle. The density of Red Sea Brine is 1100 kg/m3 The corridor for the Israelites is 10m wide. They can walk at a steady pace of 4kph regardless of slope. [![enter image description here](https://i.stack.imgur.com/ZrqOh.png)](https://i.stack.imgur.com/ZrqOh.png) Question If we simplify by saying they all leave and arrive at the same time: (a) How long will God have to hold the waters apart and (b) What will be his total energy expenditure both for opening the corridor and then holding it open? [Answer] Redrawing the original diagram to make it clear what I'm assuming the parted volume looks like: [![parted Red Sea diagram](https://i.stack.imgur.com/hpSl3.png)](https://i.stack.imgur.com/hpSl3.png) The section through the sea bed is specified to be a circular arc and so, given the constraints, we can work out the radius of the circle using Pythagoras' theorem, and the length of the arc with some simple trigonometry: [![sea bed geometry](https://i.stack.imgur.com/biS7I.png)](https://i.stack.imgur.com/biS7I.png) The distance walked is 100,007m, and at a constant speed of 1.111ms-1 that gives a crossing time of 9.00x104s (25 hours). To calculate the energy required to displace this volume of water, we need a bit of calculus. Assuming that the displaced water is lifted up to the top of the sea, and assuming that the effect on the overall sea level is negligible, then we need to calculate how much energy it takes to raise every drop of displaced water to sea level (h=0). To raise one kg of water by one meter requires 9.81 joules of energy. But the height through which we need to raise the water varies continuously with depth. We need to divide the displaced volume into (infinitely many) horizontal slices ‚Äì¬†so that each slice is at the same height ‚Äì¬†and then sum the energy required to raise each slice. [![integration diagram](https://i.stack.imgur.com/ar0xv.png)](https://i.stack.imgur.com/ar0xv.png) * the width of each slice is a function of height * the area of each slice is a function of width * the "specific mass" of each slice (its mass per vertical meter) is a function of area * the energy required to raise each slice is a function of specific mass and of height ‚Äì therefore we can write down the required energy per slice as a function of height. $$E=-9.81 m\_s h$$ $$m\_s = 22000 w$$ $$w = \sqrt{-h^2 + 5.0\times10^6 h + 2.5\times10^9}$$ $$E=-2.158\times10^5h\sqrt{-h^2 + 2.5\times10^6 h + 5.0\times10^9}$$ (I've omitted most of the algebra). The required total energy is then $$E\_T = -2.158\times10^5\int\_{-500}^0{h\sqrt{-h^2 + 5.0\times10^6 h + 2.5\times10^9}}dh$$ It's not obvious whether someone who was better than me at calculus could solve that analytically; anyway, my computer comes up with the numerical solution $$E=2.248\times10^{19}\;\mathrm{J}$$ $$=22.5\;\mathrm{exajoules}$$ For comparison, this would completely drain 2.3 million billion fully-charged iPhone X batteries. This does not take into account the energy to keep the waters parted. As others have pointed out, this depends exactly how the miracle is done; if it was done by raising the sea floor, or by creating some kind of wall to hold the water back, those are static arrangements which don't require any energy input at all. If it was more like the Charlton Heston movie ‚Äì¬†with the water seemingly flowing as normal, but being continually driven back on either side ‚Äì¬†then that would take considerable power. The description in Exodus 14 mostly sounds like the tide going out (i.e. the sea floor being raised), but verse 29 says "the waters were a wall to them on their right hand and on their left", which does sound more like the movie version. The energy to continually push the water back would depend on the rate at which it flowed into the evacuated volume, and on the height through which each drop of that water had to be raised to remove it again. A "realistic" model of the fluid dynamics would be beyond me, and probably very complicated, but if we imagine each wall as the opening of a giant pipe, where: * cross-sectional area is 4.7x106m2 * mean depth below sea level is 200m * mean water pressure is 2x106Pa ‚Äì¬†then (adapting the math for volume flow on [this page](https://www.engineeringtoolbox.com/flow-liquid-water-tank-d_1753.html)) we can estimate that each wall is pumping out 9.4x109kg of water per second. It takes 1962J to raise 1kg of water by 200m; multiplying these numbers, we get a power requirement of 1.84x1013W (about 18 terawatts), or 36TW for both sides. That figure seems quite high, but I don't know if it's an error on my part or not; it's certainly true that this would take a formidable amount of power. Anyway, over 25 hours that comes to 1.66 exajoules, or 0.3% of the world's current annual energy consumption. # Theophysics It might seem like this sort of discussion is moot, or a joke, because divine intervention invalidates the laws of physics anyway. But that's an artifact of the very modern, deeply flawed idea that science and theology are somehow opposites. Enlightenment scientists like Isaac Newton saw them as basically the same thing, and they didn't have a problem with the idea that literal miracles could be reconciled with physical laws. It's actually quite a broad and interesting philosophical area. One common approach to the parting of the Red Sea, for example, would be what we might now call a "Maxwell's Demon" model. If the universe is completely deterministic (or if, wherever quantum dice rolls are involved, God has manipulated the outcome), then every atom has been ordered, from the beginning of time, such that at the appointed time, the momenta of all the molecules in the Red Sea "just so happen" to be arranged in a highly improbable way that causes the waters to part. The important thing to note is that this doesn't violate the presumed rules of physics; it's just that God has played an unfathomably crafty game within the rules. Conservation of energy is not violated (implicitly, the energy "comes from" the thermal energy of the surrounding environment). The laws of thermodynamics are not violated because, even though it seems like a huge amount of entropy has vanished from the system, what's actually happened is that there was an entropy deficit all along, but it was hidden ‚Äì¬†essentially, encrypted ‚Äì¬†in the state vectors of every particle in the universe from the start of time. This does have thermodynamic implications for whatever was going on prior to the book of Genesis, but that is beyond the scope of the conversation. There are many other approaches to this sort of question (and to related questions concerning free will), but my point is that if you assume stuff like this happened at all, that doesn't mean you have to throw science out the window. [Answer] # Time it takes the Hebrews to cross The Hebrews walk half of the circumference of an ellipse with the dimensions that you specify. The circumference of an ellipse is $$C = 4a\int\_0^{\pi/2}\sqrt{1-e^2\sin^2\theta}d\theta,$$ where $a$ is the semi-major axis and $e$ is the eccentricity. The semi-major axis is half of the 'long way' across the ellipse, which is 50,000 meters. The eccentricity is $$e = \sqrt{1-b^2/a^2},$$ and $b$ is the semi-minor axis, or 500 meters. Thus $e = 0.9999500$. Lets just round that to 1. If we do so, everything becomes a lot easier. The integral becomes $$\int\_0^{\pi/2}\cos\theta d\theta,$$ which evaluates to 1, so half of the circumference of the ellipse is just $2a$ or 100 km. At 4 kilometers per hour, this takes 25 hours to cross. # Now, assume God is omnipotent I'm Catholic, so I think this is a good assumption. God created all things, and he can presumably un-create all things. If God simply wants to un-create the waters in the Red Sea, he can do so, for a net energy gain of $E = mc^2$, per mass unit. But, he can then create those same waters at some distance away and let them simply flow back towards the void that he is un-creating. The cost of creating those same waters is also $E = mc^2$. Normally, I would say that expecting a process to be 100% thermodynamically efficient is silly, but we are talking about God here. So assuming that God is omnipotent, and that he can create and annihilate matter with perfect thermodynamic efficiency, then the net energy cost to God is 0, to hold the waters open for any amount of time. Sorry, but if you want me to assume God is not omnipotent, you will have to put it in your question and I will edit this answer appropriately. [Answer] How long does it take? Call R the radius of the circle that the seabed follows: $R^2=(\frac{w}{2})^2+(R-d)^2=2500+R^2-R+0.25$. Solving for R gives $R=2,500.25 \text{ km}$. Then the arclength of the circle on the seafloor is $D=2R \times tan(\frac{50}{R})= 100.0333428 \text{ km}$ to be traveled at 4 km/hr gives a) 25 hrs and 30 seconds. (with 0.008522 fractions of a second remaining) \Remember the assumption in the question is that they all leave and arrive at the same time. How much energy does it take?* Instead of assuming that the water just winks out of existence and is actually moved into the surrounding red sea, then we can solve this using a potential energy calculation. First the Volume of water displaced will be $V=A\10 \text{ m}$. And $A=2 \times tan(\frac{50}{R}) \times pi \times R^2 - (R-d) \times \frac{w}{2}= 660,593.9 \text{ km}^2$, so $V=6,605.939 \text{ km}^3$, and at a density of 1100 kg/m^3. the mass, $m = 7.2665329 \times 10^{15} kg$* of water. Regardless of how this water gets there, it will, from an energy perspective, need to be lifted to the surface of the sea, so we'll need the centroid of the water being moved to see how far it needs to be lifted. The formula for the distance from the bottom of the sea to the centroid is $x=R-4/3 \times \frac{R\sin^3(a)}{2a-sin(2a)}$, where $a$ is the angle $a=tan(\frac{50}{R})$. Doing the calculations, $x=0.3 \text{ km}$. So the height that the water will be lifted is $$h=d-x=0.2 \text{ km}$$ (we could also use calculus to do this, but we don't need it) The gravitational potential energy required is $E=mgh$, where g=9.807 {m/s$^2$ so... b) $E=7.2665329 \times 10^{15} \text{ kg} \times 9.8 \text{ m/s}^2 \times 0.3 \text{ km} = 2.1378866 8 10^{16} \text{ kJ}$* It doesn't take any additional energy to hold the water in place, energy is measured as a force over a distance, and since there is no movement when it is holding still, there isn't any additional energy needed to hold it in place. [Answer] (a) is a deceptively complex question. This is basically a fluid viscosity problem comprised of 6,000,000 units (600,000 men + wives + children + "mixed multitudes" + flocks + herds). With the mix of variables between children, elderly, chaotic animals, bathroom/rest breaks, coral, mud, hectic terrain, etc you are going to see huge swings in crowd viscosity. I would think that traffic flow would essentially be stopped (at least in part) for much of the trek through the corridor. Realistically I would estimate that at the far end of a 100km x 10m corridor the exit rate would be 10,000 units per hour. In total it would take about a month to get everyone across. With perfect coordination and flow, no accidents, breaks or interruptions, and every man, woman, child, and beast willing to walk day and night it would take a little over 4 days for everyone to cross. Rows of 20 units wide 6,000,000 units/row (20) = 300,000 rows 300,000 rows \* 1 meter of separation = 300 kilometer caravan 300 kilometer caravan + 100 kilometer sea = 400 kilometers of travel 400/4kph = 100 hours 100/24 = 4.1 days With densely packed units (only 0.5 square meters per unit which includes their food, water, and possessions) perfect coordination and flow, no accidents, breaks or interruptions, and every man, woman, child, and beast willing to walk day and night it would take a little over 4 days for everyone to cross. (b) Whatever energy it takes to create or destroy energy can be created to supplement the difference. The net result is zero. [Answer] kingledion pointed to an intriguing possibility [within their answer](https://worldbuilding.stackexchange.com/a/131586/578): The stupendous amount of energy could be supplied with help of [Maxwells demon](https://en.wikipedia.org/wiki/Maxwell%27s_demon), who somehow sorts the water molecules acording to speed etc. to generate useful work. Out of sheer fun, I did the math by how much we would need to cool the water to gain the energy to lift it. Using the numbers from [Mathadicts answer](https://worldbuilding.stackexchange.com/a/131593/578), with $1.62\10^{15}$ kg of water with a specific heat capacity of $4.182 \frac{kJ}{kg K}$, to get $2.13\10^{16} kJ$ we need to cool the water by ... 0.77K. The relationship between potential (=height) and thermal energ in water is fun to ponder. ]
[Question] [ Situation A species lives on a planet with heavy fog, and as such, they rely on a conjunction of hearing, smell, and sight. The fog only allows for vision at 500 feet (~152 meters) . They have basic echolocation capabilities. The rifle "sight" uses echolocation for long ranged weapons, with a top range of one mile (~1600 meters). Differences to Normal Rifle Sights 1. Inherently less accurate. Sound travels slower than light, and the locating sound needs to travel both ways in order for the creature to get information about their targets. 2. More reliable in more settings. Only places that there may be issues are loud urban areas or space. Question Would this echolocation rifle "sight" be feasible? If so, what are some of the pros and cons I forgot about the "sight"? [Answer] If I get the question right OP asks for feasibility of a targeting device based on sound reflection. Under stated conditions answer is no. As discussed, e.g., [here](https://physics.stackexchange.com/a/255743/52299) the upper limit of ultrasound range in air is about 200 meters, probably much less with heavy fog. Situation is very different in water. [Answer] I'm the random submarine guy, and man do I have some things for you. See, when we're alone out in the water, we try to be as quiet as possible for our own good. It helps us identify what's in the water near us, minimizes false positives, and helps us stay undetected should a potential enemy show up in our patrol area. There is only one really good tactical reason you would ever broadcast active sonar pings in the water, outside of testing - when you suspect you are not alone, but you are absolutely postive you still have the upper hand once you announce your presence to the enemy. This sort of situation really only comes up in battle groups and task forces, because that is essentially the only way to ensure a tactical advantage. Even then, when you go active, you light up the water with a ping - an enemy may suddenly find himself with his torpedo tubes pointed directly at you, when before he wasn't even sure you were there. Most submarine commanders, in wartime, will take the shot they have right before they try to evade, and you stand a very good chance of dying. To point this up a bit, in 8 years of service, I never once heard either of my boats go active anywhere other than for testing in undeniably friendly water. Another thing about active sonar - you're still guessing, a bit. Yes, the guys who were listening are almost absolutely positive that the thing behind you is a whale, but now? Everything sounds like ping. You have what the computers can sort out, which might be an enemy submarine, or it might be a cruise liner through a thermocline that's making it seem to be in the wrong place. Good commanders maintain an awareness of what they think is out there, and that helps bridge the gap in the tactical picture. So, you point the rifle, start the sight, send a broadcast, probably get shot at, and you get a range ping back... But from what, who knows? It would be hard to tell the difference between a rock and a riot shield. Now stop for a minute, and consider your own, ordinary human hearing. You can probably readily identify the sound of a car shifting into reverse - it's pretty distinctive. Your brain can also pull apart the sounds from a three way conservation, identify who is speaking without looking, and give you an idea of how far away they are. As an electrician, on the boat, I knew when we lost an electrical bus the second after it happened because ventilation fans whine a bit when they're winding down. Electricians were already running for the engine room by the time anyone was talking on the announcement systems - we all knew that sound. It's your world, so by all means, if echo sights are a thing, then by golly they're a thing. But if you want a more explainable, realistic technology, what these guys need is parabolic microphones, silencers, and lots and lots of patience. [Answer] Your single biggest issue is that using a such a system is a good way to have the shooter end up dead before they're in any way prepared to shoot at anything. There are already systems that use the sound of a shot to triangulate the source, such as Boomerang, which means that within seconds of the shot the area could be getting pasted by return fire or heavier weapons. Note that's with someone actually having made the shot. In the echolocation system proposed, the sensor is, by definition, going to be advertising its position in order to function, and one of the downsides of active sensors is that they typically can be detected at a significantly greater distance than the distance they can detect anything at. So if someone tried to field such a system, the immediate reaction would be to deploy sensors that listen for an echosounder, which would detect it at a far greater distance than the "sight" would detect anything, and then send a high velocity and/or high-explosive hello back at the shooter's position. [Answer] How wedded are you to sound versus a laser? You can get all the same results but faster and more precise. Plus, if you time gate when the receiver "looks" for the reflected laser, you can effectively filter out the fog. This process is better described [here](https://spinoff.nasa.gov/Spinoff2015/ps_5.html). This could actually be a weapon sight, though determining if it is pointed at a person versus a rock would require careful survey of the battlefield first, or tracking motion. But it would deliver accurate enough location information to allow for a hit from a traditional rifle. Your echolocation system would work better if there were remote sensors placed around the battlefield that could passively listen and perhaps actively transmit. We have real world systems like this to include the GUIK SOSUS network, and even actual infantry/armor applications. [Here](https://ccse.lbl.gov/people/kaushik/papers/AIAA_Monterey.pdf) is a really detailed look at military acoustic systems, some of which kinda do what you are proposing (though using sound to pinpoint a person is very tricky). Almost all are passive though, since that works pretty well in the air. Seismic sensors to register walking, vehicles could also help. A proposed sniper system would involve the use of passive acoustic triangulation to get an approximate location of an enemy, then use an area munition rather than a single bullet. Something like the proximity minigrenade in the XM25 that allows for an effective kill just from "being close". [Answer] Tactically, no they aren't 1) If you are focusing in on produced sound you inherently require your target to make loud enough identifying sound (which they may dampen) and you are relying on your target not to employ deceptive sounds (which they could easily make). 2) if you are doing true echolocation and emitting a sound pulse in order to locate a target based on received responses you have just revealed your location. This inherently botches loads of ground tactics requiring surprise like sniping. Even submarines don't constantly emit pulses and just sit and wait. Furthermore what if your opponent is static and geometrically blended into the landscape, you have given him your position without knowing his thus you are likely to be disadvantaged. 3) The apparatus needed to do this would certainly be unwieldy with the distance and level of detail needed to be operationally effective. In short, this would be useful against an enemy who couldn't counter it. But because it is easily countered it is in short tactically detrimental. At most it would see more usage in defensive facilities. [Answer] Ultrasonic imaging would likely be an impractical way of acquiring vision in dense fog. However there are frequencies of electromagnetic radiation that are not absorbed and reflected by water vapor to the same extent as visible light. [Here is a link](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.flirmedia.com/MMC/CVS/Tech_Notes/TN_0001_EN.pdf&ved=0ahUKEwiZn8-Irq3XAhVF5IMKHbWoA0IQFghiMAw&usg=AOvVaw2NCxOoswODY9rOScCoyUkd "here is a link") to a publication by FLIR, an industry leader in infrared imaging, about using infrared to see through fog. One interesting conclusion is that to see high levels of detail using small lenses (such as through a scope) the sensors need cryogenic cooling. ]
[Question] [ So I am building giant spider species in my world, but I want to make semi-realistic changes to their physiology in order for them to be possible. * Pack hunters like [these spiders which hunt cooperatively](https://www.newscientist.com/article/dn9820-society-focused-spiders-live-and-hunt-together/) * able to drag 30-40 pound prey, but be able to swarm much larger creatures (like an adult human) Given these requirements, what changes would have to be made? How big would they have to be? I know for instance, that small spiders pump fluid into their legs to move, but this doesn't really work on a larger scale. I was thinking as well, that given current earth-like conditions, they'd also need to process oxygen better than regular-sized spiders generally do. Can creatures with an exoskeleton get this big? What adjustments would have to be made in order to meet my requirements? I know I can hand-wave a bunch because it's a mythical world, but I would like for them to work without magic if at all possible. EDIT: THIS HAS BEEN FLAGGED AS A DUPLICATE of a question about exoskeletons and size. Not only had I already seen this question and the answers there, it's the reason why I mention oxygen processing. THAT question was about crustaceans, this one is about SPIDERS. MY question has specific requirements for the creature I am building, including what they should be able to drag, and asking about what other changes need to be made (for example the hydraulic leg system scaling up). The biology of a spider and the biology of a crustacean ARE, in fact, different, from how they move, to how they breathe, what they eat, and how they hunt. @Will for example, answered the question by saying that they don't have to be large, just push the cooperative nature of them, so that they drag things together. [Answer] I was interested to see that your linked spiders have 2 castes of females. Different castes are well known for social insects. from <http://www.alexanderwild.com/> [![enter image description here](https://i.stack.imgur.com/I6Aiy.jpg)](https://i.stack.imgur.com/I6Aiy.jpg) My proposition takes a page from Komodo dragons. They are no good for sustained speed. The Komodo bites and then stalks the prey for days. I watched a tiny spider do this to a wasp caught in its web: wait, bite a leg when given the opportunity, and then wait again. All day and all night. The next day the wasp was being wrapped. Spiders are not good with sustained speed either. Spiders are good with patience and poison. You will have a biting caste of spiders. These are little and quick: regular spiders. They bite the prey and then run or get smashed. Once bitten the prey starts to get sick. It takes a while. The stalking spiders come. These are larger. They are not fast. They see very well. They wait in the shadows. When the prey gets sick enough, they come in as a team and wrap it up. The stalking spiders are not huge either: maybe the size of guinea pigs. Once the prey is wrapped it is slippery, and the wrap is parallel to the long axis and the eventual direction of travel. The silk acts like runners. The stalking spiders drag it away like a dogsled team, each attaching its own silk and pulling. More weight to pull = more spiders to pull it. The period between getting bit and the stalking spiders taking you away offers narrative possibility. The stalking spiders are like death. They are very, very difficult to escape. Sentient prey will know they are coming. [Answer] Simple answer: your giant spiders aren't really all that much like regular arachnids. In detail: your basic need is to figure out which features or regular spiders will scale and which ones won't, while preserving the (at least perceived) sportiness. Exoskeleton: this should scale okay. You might have some features such as legs and joints a little overscaled, as they may need space for actuation. Animals of large scale already possessing exoskeletons are lobster (and other creations), turtles (perhaps this is a stretch, bit the mechanisms could be carried over), and armadillo (again, not strictly an exoskeleton, but an option). Number of limbs: this should be able to stay. More limbs means each one doesn't need to be as powerful, although your spiders probably won't be breaking land speed records, as the increase in limbs around a comparable space for animals of a similar size means less space for limb operation, and thus a higher number of limb direction reversals over a given distance than a creature with fewer legs. Cardiopulmonary: give it lungs and a heart like all the other big animals and it'll be just fine. The lungs could work off a relatively fast moving pumping muscle that forces air around the gas exchanges in its abdomen and out through backflow-blocking cartilage somewhere. Or they could be more material, perhaps with a shared wall diaphragm, where one lung contracts while the other expands to maintain constant volume. Actuation and digestion: this may be more tricky. You could use the fluid pumping method of smaller arachnids, but this would require significant musculature and hydrolics in what will be an already crowded body. Here's the note in digestion: a spider typically emulsified and drinks it's prey. In a large scale, this may not be practical. They'll need a more mamillian digestive tract to extract the amount of energy they need from the amount of prey then y can catch. Big predators like wolves (in packs) or cougar have to for days between meals sometimes. If megarachnid gets all her food from just the available juices, even with acid spit up for some predigestion of solids, it simply won't last long enough between meals to be competitive with other predators. That said, moving back to actuation , the legs may actually be pretty easy. An exoskeleton gives you a whole lot of room for muscle. And, when you have eight legs, you don't need as much power in each leg. It would probably be just fine by that reasoning to replace the hydraulics with some muscle tissue. Webs: not specified in the original question, but worth dealing with. Spider webs are made almost entirely of special proteins. So, your spider needs a lot of high energy density food (definitely a predator then). And, while it may seem like that would be a problem on large scale, it may not. Spider silk is close to steel for tensile strength and much tougher on a deformation v. strength curve. It would probably not be inconceivable then for a spider of this magnitude to spin enough silk for low quantity regular use or the occasional net trap or web nest. Spider appearance: let's see, eight legs, exoskeleton, more than 2 eyes, general scariness—yep, I think you're good! Edit: to address the pulling capacity: a 30 to 40 pound dog can drag its own weight if the distance is not to great. If this spider has similar musculature spread around eight legs, it could do the same. If it had double the musculature (that is, similar per-leg musculature to the dog), it could be half the size (of said dog, an example of which would be a large Spaniel or a small Labrador or Bulldog). [Answer] You should take a look at Coconut Crabs: [![enter image description here](https://i.stack.imgur.com/LjGgL.jpg)](https://i.stack.imgur.com/LjGgL.jpg) which are amazing/frightening depending on one's perspective and distance from them. They can spend long periods out of the water and can do fairly dexterous tasks, as shown! More info in these critters at: <https://en.wikipedia.org/wiki/Coconut_crab> Among other things, they can climb coconut trees, cut the nuts free and then break the nuts open for food. Imagine if they could move faster, e.g. with greater O2 concentration or some other bit of handwavium.... ]
[Question] [ Every single depiction out there seems to think that animal teeth and/or mouth are no problem for a perfect speech-therapist approved pronunciation. For instance the Cat People. They never have any specific accent other than Spanish. So for our possibly speech-impaired cat people, let's assume that the vocal chords remain the same as ours. Dentition-wise, we'll go with chimpanzee teeth but tighter (an arbitrary "middle ground" between human and feline teeth), like so: ![is Paint still a thing?](https://www.hostingpics.net/thumbs/76/99/33/mini_769933teeth.jpg) With such dentition and regular human lips, what sounds would be hard to pronounce? I heard that long canines give a lisp, but would people born with long teeth overcome it? What about cat or wolf chops on an otherwise human face? (still with human vocal chords, and teeth as pictured above) More or less like this: ![example](https://i.stack.imgur.com/ZIVKg.jpg) What about Lizard People? Can this jaw really produce every sound we can? ![Vangaa](https://i.stack.imgur.com/lPKvn.jpg) And Bird People? Parrots are really good at imitating us, but it MUST somehow be harder to speak with a beak! ![Tengu GW](https://wiki.guildwars.com/images/e/e6/Tengu_concept_art.jpg) Unlike depicted in most media, there is no way they would be able to pronounce the same sounds as humans, is there? What would they be unable to pronounce? What could they pronounce that we can't? [Answer] It is not so much the jaw with human speech as the vocal chords. [Early attempts to teach chimps to speak](https://en.wikipedia.org/wiki/Viki_(chimpanzee)) have very limited success because chimps don't have the same vocal chords that we do. [Later attempts using sign language](https://en.wikipedia.org/wiki/Washoe_(chimpanzee)) showed that chimps were capable of very sophisticated language use (mentally) - they just needed to use words they could physically reproduce. Several bird species (Like the Australian Lyre Bird) have an uncanny ability to mimic just about any sound, and they have teeny pointy little beaks with no teeth at all. So your articulate aliens might be using a similar mechanism. The other important aspect is the tongue - a lot of consonants require specific tongue movements, and vowels are also created by changing the shape of the throat cavity, using the back of the tongue. If you have ever listened to somebody who learned your native language as an adult, you will notice that they often mumble, lisp, or otherwise mangle some consonants. This is nothing to do with their physical structure - it is because they didn't HEAR those sounds during the first two years of their life. It is entirely possible that with human vocal chords and tongue, and learning from birth, your pointy-toothed humans could sound exactly like us. Otherwise, a few basic linguistic notes: * Lips that don't properly seal would soften /p/ to /w/ * Teeth that don't fully close would soften /dÕ° í/ to / í/. * Someone with a natural ability to purr might be prone using /r/. [Answer] So... you asked about "humans". Accordingly, per [JJH's answer](/a/61442/43697) noting the important effect of vocal chords, I'm going to assume that we're talking about human vocal chords (or at least similar capabilities) and are mainly focused on the limitations due to teeth and jaws. (I'm also going to assume a fairly mobile tongue; otherwise, consonants such as we know them are going to be an issue.) Honestly, this *really* depends on whether you're actually asking about "humans" (and/or for some reason want to parallel human ‚Äî and in particular, European/American ‚Äî language development) as opposed to trying to create a language for a totally different sapient species, in which case humans might not even recognize their language as such. Still, your audience is human, so having something relatable may make sense. With that said, I'd like to offer the phoneme set I came up with from my own tinkering before seeing this question. This is mostly based on my best guess what limited lip mobility (including inability to fully close the lips while speaking) would do to a language that humans could still speak and recognize. Also, I was approaching this from a perspective of trying to avoid species-specific noises, i.e. something that could be a common tongue in a world of anthropomorphic animals of many species (e.g. [Zootopia](https://en.wikipedia.org/wiki/Zootopia)). One thing this doesn't necessarily account for is the effect of larger teeth, although I don't think that will be severe. If you want to explore that, find yourself a set of fake vampire teeth üôÇ. Ahem. Without further digression: ### Vowels * Open + `a` ( …í ): lock + `e` ( e ): lake * Forward + `i` ( …™ ): lick + `y` ( i ): leak * Round + `o` ( ä ): look + `u` ( u ): luke You might be able to add more vowels ([…î] in particular), although it may start becoming difficult to tell them apart, especially if you have regional accents ([…Ø] and [ ä] for example are very similar). Also, I was somewhat trying to keep the set minimal, as that is beneficial for a language shared by many species. I'm also not considering dipthongs separately, so e.g. [w] and [j] are "on" the chart, but would be represented as [u]+[…í] and [i]+[…í], respectively. ### Consonants * Palato-alveolar + `c` ( t É ): chock + `j` ( d í ): jock + `ch` ( É ): shock + `jh` ( í ): jacques * Dental + `t` ( t ): ten + `d` ( d ): den + `th` ( Œ∏ ): thick + `dh` ( √∞ ): then * Stop + `k` ( k ): ruck + `g` ( g ): rug * Fricative + `s` ( s ): sue + `z` ( z ): zoo * Others + `h` ( h ): hick + `l` ( l ): lick + `n` ( n ): nick + `r` ( …π ): rick --- One of my additional objectives was being able to write this language phonetically in ASCII (i.e. using only the English letters A-Z); I've given both that representation as well as the IPA equivalents. Normally, you wouldn't have a `c` or `j` immediately followed by a distinct `h`, because that combination is quite hard to pronounce without an intervening vowel. However, if really needed, this could be written with an apostrophe, e.g. `taj'ha`. [Answer] ## We would not be able to comprehend them, or learn their language Note: we don't know if animals like cats, dogs, birds or cattle have language. Animals, or some animals, could very well have language already, without us being aware of that fact. The point of this answer: we would have trouble interpreting it as language. Let alone comprehend it. Speech is closely tied to physiology Our speech is 1:1 tailored to our physiology. Our vocal tract and mouth can produce a familiar sound spectrum, allowing humans to discern (tell apart) hundred or more phonemes, which represent speech. Humans are able to produce a wide variety of sounds we can recognize, compose with and call "language". Animals have a different physiology. Their sounds are unfamiliar to our brains, Their nicely separated phonemes may sound the same for us, because we did not learn to discriminate in our perception. Example: bear people Supposing bear people will have bear heads, their speech will not sound very clear to us humans. In many ways, bear speech would be very different from human speech. The bear head is larger and also broader than a human head, meaning lower frequencies. bear people vowels We can hear them. I don't think frequency range is the issue, rather physiology of the bear's vocal tract and mouth. Our ears are not used to the frequency ranges (sound spectrum) produced by mouth-dimensions of another species. A "bear vowel" may not sound like any particular vowel humans recognize. As a result, humans will also not be able to discern different bear vowels. We did not learn their characteristics. So it will be difficult to learn any animal's language, or the language of a human with an animal head, for that matter.. bear consonants A "bear consonant" can come from anywhere unfamiliar to humans. The lips have a different shape, longer and wider to the back. There could be 12 types of "b" and "p". The nasal channel is also wider, the teeth are larger so the animal will produce lower frequency noise than humans.. too low would impair bear-consonant recognition by humans. My conclusion: for a human, it would be very difficult to communicate with a bear-man.. or a cat-man.. or whatever fantasy human with an animal head. ]
[Question] [ For over a thousand years, the dreaded dragon Lohebrand has roamed the plains of the east. His breath melts mountains, his shadow blots out the sun, the earth trembles beneath his talons – or so the singers day. He has claimed the land as his own, driven almost all humans from it and feast on the herds of wild cattle that roam the plains. Even the sight of him flying on the horizon, leagues away, makes warriors quake with fear. But one question remains unanswered: Just how big is he, exactly? Fluff aside: I am working on a Medieval Fantasy Setting, and I have no idea how to scale this dragon. Lohebrand is supposed to be ancient and wet-your-pants-don’t-even-think-about-fighting-scary. And, of course, as gigantic as realistically possible. (At least, realistic as far as dragons go). Some facts: * Territory: Lohebrand claims about 25,000 $\text {miles}^2$ as his own, mostly plains that turn mountainous towards the North and West. The land is fertile, but mostly devoid of humans. * Diet: Horses, wild cattle, goats, sheep and humans foolish enough to enter his territory and be discovered. * Age: About 2000 years old. My idea was that a dragon will continue to grow (not necessary consistently) as long as his environment supports this. Assuming Lohebrand does not care for husbandry, but is smart enough to change up his hunting patters to try and avoid over-hunting—just how big could he possibly have grown? And how would this relate to proportions (i.e. wingspan, size of his head)? The bigger, the better, of course… [Answer] I assume that your dragon is not limited by biological issues like the square-cube law of muscles (scaling up a muscle means scaling up its strength in a quadratic fashion; however the weight scales up in a cubic fashion. Meaning: the bigger the dragon gets, the more muscle it has to invest in simple things like walking let alone flying). Also, temperature issues follow the same square-cube law: a body's heat production follows the cubic law, the cooling surface follows the square law (= the bigger the dragon gets, the more likely it is to have overheating issues). Not to mention that at a certain point the body might just break down from its own weight (bone strength, blood pressure, etc.) So basically all you limit your dragon by is its food source and the energy it can gain from it. For one, you definitely need to minimize the energy requirements of your dragon. Your dragon should be coldblooded so that it doesn't need as much energy for its base metabolic rate. Also, the more you can outsource to magic instead of conventional energy (e.g. generating the energy for breathing fire) the better for your dragon size. That is, assuming that magic doesn't require conventional energy to regenerate. The [ecological pyramid](https://en.wikipedia.org/wiki/Ecological_pyramid) says that approximately 10kg prey are needed to sustain 1kg predator. When optimizing your dragon, you might be able to go so far that 1kg dragon mass requires only 5kg prey. So, a very simplified calculation might give you the following: Assuming your 25000 sqmi can sustain 10,000 horses/cattle/other big herbivores with an average mass of 300kg per animal, you've got a total prey mass of 3000t - or a predator mass of 600t. So your dragon weighs 600t. How big should it be? Well, an airbus A380 is sized for a maximum takeoff weight of [580t](https://en.wikipedia.org/wiki/Airbus_A380) with a wingspan of 78m and a total length of 73m. I think that is the minimum size requirements to get your 600t dragon flyable. However, the A380 weighs only about 280t when empty -- which might be a better comparison to your dragon. On the other hand, jet wings are a lot smaller than wings needed for gliding, so at least triple the wing span. So, all in all, I'd say a wing span of 200m with a head-to-rump length (no tail) of 80m is a good estimate for your dragon size. EDIT: Of course, this link here is a [more realistic view](https://sites.google.com/site/anthonysgurps/dragon-physics) on dragon sizes when creating a physically possible dragon. Meaning: any dragon above 70-200kg is just about impossible thanks to biology and physics... [Answer] As you've said this beast is capable of flight, it's important to note that the bigger it is the more force needed to fly as noted by the [Square/Cube Law](http://tvtropes.org/pmwiki/pmwiki.php/Main/SquareCubeLaw). You've already mentioned that this dragon is capable of keeping enough prey alive to sustain itself but even then, following the usual lore of Dragons, they would eat until they filled their stomachs and sleep for long amounts of time (even centuries). Assuming the dragons internal structure was more focused on big-bones, muscle and wings, than I would suggest it's largest size equal that of a [Spinosaurus](https://en.wikipedia.org/wiki/Spinosaurus). Based on this [Whatif page](https://what-if.xkcd.com/78/) your dragon (if it were around the size of a Spinosaurus) would need to consume around 1 human every day, therefore in a Medieval setting it's possible for the dragon to each as much as 300 - 500 humans/animals and sleep for the year without disrupting the balance of the local area. [Answer] This is not my usual advice, but... absolutely ignore all the physics and biology advice. Pratchett had the right idea. You simply cannot justify a dragon using any kind of common sense. They merrily violate any kind of sense. Dragons are thaumic creatures. Sure, they'll roast you and eat you but that's as a snack. Your princess is candy to a dragon. The wild animals it hunts for fun are just bacon sprinkles. Dragons cross the planes into the Dungeon Dimensions and what they catch and eat there has so much magical power that they then can lie dormant for hundreds of years just digesting and lying on their hoard. Our dimension is comfy. Warm. And has candy. A long-lived dragon can be any size you feel it to be narratively relevant. Those old legends of his size may be out of date. The adventurers go there expecting something the size of perhaps a sailing ship in the cave under a mountain, then as they crest the top of the last hill and look up at it, they realize the mountain on the other side is, very slowly, breathing. Physics and realism is great, but don't ever let it get in the way of being cooler than people expect. The Rule of Cool is there to back you up if you waver. Unless you are actually out to make the anticlimactic downplay part of the tale, in which case, the dragon should probably be a little old guy with an old leather hang glider and a bag of levitation and flame runes, who retired form his dragonning days years ago. [Edit: that said, don't make a dragon fat. Think lithe, lissom, and massive. At worst, a tiger. Not an elephant. That's the trap that physics-respecters fall into. A dragon mostly covering a mountain that he is sprawled over, is scarier than a dragon who is a mountain.] [Answer] If you're saying that their biggest prey is a horse then a dragon should be 3 to 12 feet long (without tail) because the general size ratio between predators and prey are between .5 to 2x that of the predator. In the abstract of this paper are those findings <https://www.jstor.org/stable/20143171?seq=1#page_scan_tab_contents> The tail of a dragon would add between 50 and 100% more to his body length... So 18 to 24 feet on the large size. Wing spans are usually about about 30 to 50% more of the body length so I'd go with at least 18 foot wingspan up to 36 feet. This is ignoring that dragons would need a ton of coalories to produce fire, flight, and be intelligent. And that fire is a necessity to intelligent dragons btw because cooked food is the only way humans can eat enough to have energy to spare on thinking. We're talking a diet of something like 100,000+ calories a day. A big horse may feed a dragon for 7 to 9 days. So whereever it hunts would need to produce at least 50 full grown large well fed horses... I'd bet on needing more though as these are really crudely gotten numbers ]
[Question] [ Yet another one of my attempts to create an interesting/different feeling for an alternate government, while being functional. I'm asking about a theoretical world that exists, not necessarily transitioning our world to it, and am mostly looking for ways to make one functional, though I'm open to any criticism that says such a government simply could not work. The idea of this one is simple, length/severity of punishment of a crime may be adjusted depending on confidence level that the accused committed a crime, in theory this will prevent those who may have been falsely accused from facing as severe punishments since they are less likely to be confident. The steps would be similar to our current system, except in actual ruling and assignment of punishment. A jury will be asked if the prosecution met a certain minimum burden of proof to find the accused Guilty, if so they will be asked to what burden of proof has the prosecution proven this guilt. The minimum burden of proof may, or may not, be the same as our current one. For instance the minimum burden may be set at "Clear and convincing evidence", the same burden held for civil trials in the US currently. At the minimum level a defendant may be found guilty, but with little, if any, punishment. A number of subsequent burden levels exist that the prosecution may be found to have met. So here is a sample of the levels of proof a persecution could be found to have reached, these are just an example, I'm not saying the government has to use these levels: 1. "clear and convincing evidence" (current burden for civic cases) 2. "evidence without dispute" (no alternate explanation for the crime exists that is deemed creditable, ie no one else could likely of done the same) 3. ...some other stricter level here... 4. "beyond a reasonable doubt" (current level) 5. "Beyond a reasonable doubt, direct evidence" (requires clear direct, ie non-circumstantial, evidence in addition to above, your going to need DNA or something similar" 6. "beyond a shadow of a doubt" (requires something like clear video recording the entire crime occurring and that the accused did it, or hundreds of witnesses who could clearly see their face and cops arresting you in the act; basically you can't possible imagine this person could every be innocent) These burden levels would likely be pounded into people by their culture, and be covered in civics classes in schools regularly, so people will likely have at least some idea of the difference in severity of each by the time of adulthood before being called to a jury. Now imagine for instance Bob is accused of murder. The law may set punishments as: 1. recorded as guilty, no punishment 2. 1-3 w/ parole 3. 5-15 w/ parole 4. 25-life w/ parole 5. 30 - life with or without parole 6. 30 to life with or without parole, or death penalty Notice, it's not an even scale, the lowest levels of proof are substantially less punishment then the higher levels intentionally, so if you were unfairly found guilty you don't suffer significant punishment. In addition some crimes may be written to require a higher burden of proof to be found guilty at all. Notice it's possible in the above example to get life for burden of proof level 4 but only 30 years at the next burden of proof, so that the jury still has some discretion on appropriate punishment based off of things such as severity of the crime and justifiability etc. Even someone who was proven indisputable to have done a crime may be seen as having a very justifiable reason and unlikely to do it again making a less sever punishment make sense then someone found a level 4 burden but horrible motives. In addition capital punishment is only an option with the highest burden, since one of the complaints against capital punishment is that it could be used against an innocent man by mistake it seemed a great example of the sort of punishment that may be reserved for only the highest burden of proof. In my example level 1 for murder was no punishment at all directly. However, he would have on his record that he was found guilty for all to see, which could have other affects. he may lose the right to vote and have to report being found guilty of a felony to employers etc; and obviously it could be relevant if he is ever put on trial for murder again and had been found guilty of felony murder. Of course everyone would ask at what burden of evidence he was found guilty to measure how to respond to a conviction. Of course all the above is an example, I'm asking about a general idea for a system, the exact level of burden and severity of punishment per burden isn't as important as rather or not they system is functional. Given a system like this, would the system work? It doesn't not need to meet our vision of justice, but would it serve as a justice system that sufficiently discouraged crime without paralyzing itself with too many court cases or too many people in jail etc. What sort of difficulties would it face? Most importantly, could this system allow a minimum burden of proof lower then our current (with very low punishments) or would the minimum burden have to be our current one? If it did work what would it do better or worse then our current system? What obvious rule would need to be in place to support the system and make it function in a relatively just manner (for example, perhaps laws would need to be in place to decide how public certain convictions are, burden of proof of level 1 are only made available to law enforcement and if someone is on trial for a related offense, potential employers can check if applicant had felony of level 2 or above, public can see level 3 and above etc to avoid felons being punished too severely after they serve their time). If I get interesting responses to this I will likely ask follow up questions about affect on culture, government etc. However, if anyone has any interesting ideas of the ramifications of such a policy they wish to mention now feel free to do so, it may fuel follow up questions :). [Answer] You system could certainly work, its no less logical than what we do now and in my view it helps eliminate the all or nothing mentality that comes with some current legal practices. Heck in the case of murder we already grade it out so you're half way there, you just have to adjust the scale a bit based on burden of proof (which is only split two ways in the US (Criminal vs Civil). [US Federal Law](https://en.wikipedia.org/wiki/Murder_(United_States_law)#Degrees_of_murder_in_the_United_States) Offense -- Mandatory sentencing * Involuntary manslaughter -- Fine or up to 8 years imprisonment * Voluntary manslaughter -- Fine or up to 15 years imprisonment * Second degree murder -- Term of years to life * First degree murder -- Life imprisonment or death sentence As to its effectiveness...well that is a matter of speculation but a few benefits and problems do come to mind. Pros: * Life is easier on Juries in big cases (particularly murder cases). No longer are they deciding between someone's life and their death (or at least life in prison) in most cases. I would personally be hard pressed to consider anything but visual confirmation + DNA as enough to give someone a guilty sentence that will lead to the death penalty. * Eliminates the need (if there is one) for mandatory sentencing which robs judges of their freedom in their authority to sentence individuals. Everything works on the scale instead. * Creates a two part scale where one axis is crime severity and the other is certainty which seems a much safer system than a simple Guilty/Not Guilty all or none system Cons: * There is a potential issue with everyone getting a sentence even in the case where they are completely innocent. Just like people tend to not circle the extremes on a survey sheet (1 or 10) people may not use either end of the spectrum, which means MORE people could be potentially found guilty when they should not be...the punishment would just be far less severe. * You have a potential for far more cases going to trial which would require more judges, money and support. * Get the conviction that is easy as opposed to what should be done. Lower burdens of proof would be far easier to accomplish and prosecutors may choose to go for them rather than a first degree murder charge for example, even if murder in the first is what should be pursued. To clarify I am not saying that the prosecutor would choose the charge. The system would decide the charge and punishment based on how things went rather than deciding ahead of time. I am more referring to how deep the prosecutor digs and how hard he/she tries knowing a weaker conviction is likely with less effort. --- Strangely I don't really see this system being terribly different from the system we have no (given that you keep the system the same outside the changes you specify. In the end the legal system is still a system created by humans who make bad choices and have bias, those flaws you simply can't be rid of no matter what legal framework you utilize. > > Would it serve as a justice system that sufficiently discouraged crime > without paralyzing itself with too many court cases or too many people > in jail etc. > > > If properly applied and adaptive with time, yes. This again is the human factor...tough to gauge. > > What sort of difficulties would it face? > > > The cons mentioned. > > Most importantly, could this system allow a minimum burden of proof > lower then our current (with very low punishments) or would the > minimum burden have to be our current one? > > > You could certainly have a lower burden of proof than what is currently expected if the punishments are correspondingly adapted. > > If it did work what would it do better or worse then our current > system? > > > This is tough to answer, application is everything when it comes to law. > > What obvious rule would need to be in place to support the system and > make it function in a relatively just manner? > > > You would need to define somewhat objectively what makes a crime fit into a specific category. [Answer] It might work, but you would face two problems compared to our current justice systems that would need to be addressed: * There already is a strong benefit in destroying evidence for criminals. This would only get worse with degrees of certainty. If everybody saw you set the house on fire, but there is no direct evidence left that you killed the people inside, you might get the heavy punishment for the arson, but the lightest one for the murder, if at all. Contaminating crime scenes with DNA from other people might also become popular, until people start wearing surgery clothes to use public transport or go to the supermarket. * Juries would convict much more often. The all-or-nothing choice of guilty or innocent makes the jury directly responsible for the bad things that happen after, and most will carefully consider whether they really are sure that this person did the crime before voting them into prison for the rest of their lives. If however they have an alternative in the form of a lighter punishment, the temptation will be great to think "I'm not convinced beyond doubt, but he must have done something, so he probably deserves a few years. Let's go with level 2." In summary, it would be just like the current system: Good for the rich and smart, bad for the poor, dumb and minorities (esp. because of #2). Jury selection would still determine the outcome of many cases. [Answer] A system that I came up with for a nation in a RPG that I was running was very similar to this. In the system I came up with, a criminal case had a jury of 13, with 4 jurors being peers of the accused, 4 being peers of the victim, and 5 being peers of neither (where possible). A peer is considered to be a person of equivalent socio-economic status, and not just 'any responsible adult'. The trial was conducted, evidence was presented, and then the jury was given a set amount of time in which to deliberate based on the amount of testimony and evidence presented - no early or late returns are permitted save for illness amongst the jurors. This deliberation time was typically 1/8th of the time spent in court, i.e. 1 hour per day in court. When the jury returns, the jurors individually fill in a secret ballot as to their verdict. It takes 7 or more guilty votes to convict, and the sentence is proportional to the number of guilty votes in excess of 6, from a relative slap on the wrist at +1 to the maximum penalty at +6, depending of course on the offence. The maximum punishment for many offenses is death, but since it is difficult to get 13 guilty votes, that sentence is rarely imposed, typically only for the most egregious and incontrovertible cases. Additionally, if only 1 or 2 jurors vote Guilty, then the prosecutor's office is liable for the defendant's costs, and the prosecutor could be censured for wasting public money in bringing a prosecution where there was insufficient proof of guilt, and with a sufficiently high career censure rate, could be disbarred. If no jurors vote guilty, the defendant's legal fees are covered by the prosecution, the defendant is compensated for loss any loss of income and their perceived defamation in having been subjected to arrest and prosecution, and the prosecutor could himself be prosecuted for malicious prosecution, and face immediate disbarment and potential jail time. This system encourages public prosecutors to be absolutely sure of their cases before wasting public money on court time and putting defendants who must typically pay for legal representation to the expense of mounting a defence, since a lack of prosecutorial effort could literally be punished. This is a parallel to the ancient Roman legal system, where a prosecutor could (literally) be branded as a calumniator if their prosecution failed. It also allows for the fact that there are frequently jurors who will not agree with the majority just so as to draw out the deliberations, or who will vote impulsively or 'with the crowd' in order to be relieved of their duty in as short a time as possible. The odd number of jurors ensure that there are no split decisions - there will always be a majority one way or the other, since abstentions are considered to be a Not Guilty verdict. Sentencing is not left up to the judge, who is purely a procedural arbiter, eliminating the possibility of accusations of judicial bias or lack of community understanding that have plagued judiciaries in many other jurisdictions. [Answer] A society could work that way, and I'm not sure if it is strange enough to produce the "not in Kansas any more" feeling. Consider the effects of plea bargaining in the real world: * If the prosecution is really sure that they will win, they'll go to trial, especially for something like murder. * If there is some doubt, they might go to trial and suggest that there could be a [lesser included charge](https://en.wikipedia.org/wiki/Lesser_included_offense) as a verdict if the main charge does not stick. * If they are even less certain, they bargain for a lesser included charge with much reduced punishment instead of going to trial. Regarding your punishment scale, would all those cases get a criminal conviction for murder on Bob's record? Over a lifetime, that could be [worse](https://en.wikipedia.org/wiki/Ban_the_Box) than 1 to 3 with parole. [Answer] You would have to give up some fundamentals of jurisprudence for that to happen. Most importantly you give up the two probably most revered ones: * Presumption of innocence. Normally phrased as "Innocent until proven guilty". This is normally a binary state with very clearly defined borders, either we see you as guilty or we see you as not guilty. Here you have made that into one big grey area. "Was he guilty of that murder?", "Eh... well... kind of... a little... not a lot... but some". * Proportionality. The principle that the punishment must fit the crime. Here you are throwing that out the window and saying that the exact same actions get punished differently depending on the level of evidence. Iff(\) you get people to consider these things as not very important, then you can have such a system. But why would you want to do that? We have these things for a reason and that is that... No-one likes to be judged for something they did not do, not even a little. Acting unlawfully is shameful. No-one is going to submit to being judged as if they did something unless they have to, i.e. it is proven that they did it. And then you are just back to what we have now: innocent until proven guilty. * No-one likes unfair treatment. If I am going to made to suffer by the hands of someone else, then I should at least get the same punishment as the next guy that did the same thing. Heck even [animals adhere to this principle](https://www.youtube.com/watch?v=GcJxRqTs5nk#t=12m45s) (the segment starts at 12m 45s). Unfair treatment will result in heavy resentment and a lack of respect for the legal system. So sure, you could possibly do it.... but I very much doubt you can get people to like it or think it is a good idea. (\*) iff = if, and only if... ]
[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/18215/edit). Closed 7 years ago. [Improve this question](/posts/18215/edit) I actually had been thinking of posting a groundhogs day question the same day that [Tomorrow is Groundhog Day... For everyone. How does society respond?](https://worldbuilding.stackexchange.com/questions/18051/tomorrow-is-groundhog-day-for-everyone-how-does-society-respond) was first posted ironically, it's a sign! In my scenario assume someone was thrust into your standard groundhog day loop, repeating a single day over and over. They are an average joe, or perhaps a little smarter and better off then average (say upper-middle class), but not rich or possessing of special traits or skills, and they had not planned to start the groundhog day loop before it happened. They have determined the cause of the groundhogs day loop and now believe they could stop it on any day. Once they exit the loop they will never be able to re-enter a new one. So, how does one exploit the loop they are in before ending it? Specifically say that this person's primary goals are to help others. He is not a saint, and would appreciate and do anything to improve his own quality of life (and I'm interested in approaches he can take here), but he is mostly interested in helping others by using this unique opportunity. He has the advantage that he can choose which day he exits the loop near the end of the day. Thus he can try for a 'perfect' day and if something does work out keep repeating until it does before exiting. Now lets apply a few limitations 1. He is pragmatic and willing to bend a few rules for the sake of the greater good, but he is still restricted by moral views. He does not want to lie or manipulate others (using his 'psychic' future predicting powers) unless there is a major and immediate good. 2. He is not certain what happens if he dies, but he is not guaranteed to come back to life next loop. Thus he is not going to take any absurd risks 3. He will not repeat an infinite number of loops. The constant repeating of the same day without progress can grow repetitive and eventually drive one insane if done enough. In addition he is worried about 'forgetting' seemingly silly things. He may have seen someone chronologically 2 days ago; but after 50 subjective years of groundhogs day repeating he could forget the face of his own girlfriend he saw 'yesterday' etc. Thus he can not an will not repeat forever to master every skill in the world etc. He is willing to do many repeats, and in fact could experience subjective years, but only so long as he feels he is making clear progress. Any idea that takes many subjective years to work towards should include things he can do to help him feel like he is making progress and keep sane through the efforts. 4. He has an average to slightly below-average memory. He will be limited on how many facts he can remember each day, unless he spends a good amount of time training himself to memorize those facts and repeating them to himself every few days to reconfirm them. 5. He would prefer to go back to a normal life after this is all over if possible. He does not particularly want publicity and, while willing to tolerate it, particularly in the short term, does not want to be some media sensation. He would prefer to find approaches that don't draw long term attention, and particularly avoid doing anything that can't be explained by him being at the right place or dumb luck, if he can avoid it. He is, however, willing to draw more attention if it does enough good to justify it. 6. He is no older then 30, with decent savings and is a quick learner, but is not a genius, has no super powered friends, and generally is not going to be able to call in favors or use any political power to make something happen on a given day. I don't care what his job is, so it's acceptable to suggest he has a job or skill that would be useful so long it's not a particular rare job/skill and a 'normal' person could be expected to have it. The original groundhogs day suggested doing small things around your town, by finding out exactly where you had to be to be at the right place at the right time. I don't think this was looking far enough. With the ability to know practically anything about the world you want a day in advance, enough time to plan out and even try multiple options before picking the right one, and the ability to retry crazy one-in-a-dozen potential outcomes until they work out surely a far larger amount of good could be done. Were not limited to local good either, improving the lives of some stranger in China is just as good as that of his neighbor if he can do it. What are some viable options to exploit the groundhogs day loop to improve quality of life? I'll throw out one option now, win the lottery. He can win one, or multiple lotteries at the end of the loop, perhaps even plan out which to win to get the most money with the least attention. Maybe he buys scratch off cards that he has determined are winners (from trial and error) all on one day and cashes them in over years so as not to draw as much attention. He could also take all his money and gamble it at a casino in an all-or-nothing gamble and keep trying till he doubles or quadruples his money. This money could then all be donated to efficient charities. He would be 'stealing' the money from those who would win it, but he will use it to do more good then the other winners would. He could also try to find disasters he can warn others about to avoid them happening. No 9/11 or Chernobyl style disasters occur on that day; but surely some smaller disasters would occur around the world ever day. With time perhaps he could find out many of these 'smaller' disasters, where 'only' a few dozen to a few hundred die, and figure out who to call in an anonymous warning to in order to avoid them? Though I'm not sure how he would find any that aren't reported on his local news? What other ways can he make large scale improvements, or small scale improvements with minimal effort (so he can do many at once). [Answer] Crime-fighter Which is not to say that there's any point in him going out and stopping crimes that day. But what he can do is use travel, phones, and computers to ferret out information on criminals and set them up to be taken down in the future. He can basically hack his way into anything, and his huge advantage is he doesn't care if he gets caught. That's just more data for him to work with the next day. Whether it's technical hacking on a computer, or [social engineering](http://en.wikipedia.org/wiki/Social_engineering_%28security%29), the fact that he can try things without worrying about the consequences is a huge benefit. So what he should do is use those techniques to find evidence of crimes on as many people as he can remember. Then when he exits the loop, he can expose that to the FBI or whatnot. He should be able to take down or significantly hurt mob bosses, white-collar criminals, drug runners, etc. Maybe even terrorists, or people currently hiding who are guilty of war crimes, things like that. [Answer] Actually, this is not really too broad a question as the solution is actually the same regardless of circumstances, only the details differ. This is because in this kind of loop the changes you can affect in the world are limited by the time, one day, which is generally small compared to your overall lifespan. In contrast the changes you can affect on yourself are generally much larger as the information and skills you learn in one loop usually remain. Thus the best use you can make of this is to study anything you have any interest in. The study might involve experimentation needed to build some invention or physical exercise. It specifically includes studying yourself. That takes time and reflection. A time loop is the ideal place for it. And then after you get bored with that use the advance knowledge of the day to break the loop and do some manipulation. You could of course use that advance knowledge to make lots of money, but it is generally better not to optimize too much on things that are not hidden inside your head. A person who has studied quantum physics "on his free time" is weird and unusual, a person who makes a bunch of highly profitable investments in a short time is subject to visits by people who check in their sense of humour when they arrive at work. It would look pretty much like insider trading or money laundering from outside. The same is true for most other get rich schemes. So just use the nearly infinite time at your disposal to make yourself the best person you can be and then move on with your life. For example if you wish to help other people, become someone who can and then, after the loop ends, go do it. [Answer] Wonderful question! I have a few of my own: Does the person have a strong sense of calling in their life? People with a strong sense of calling - pastor, missionary, doctor, environmentalist, social justice advocate - will have the easiest time of it. They can perfect knowledge in their area of pursuit. Take pastor for example. The person might not have the time and money to attend seminary. Now they can study Greek, Hebrew, theology, pastoral counseling, etc and try out what they learn on the people around them. As for using the information they learn like a "psychic", they would of course interpret the Groundhog day thing as a miracle and assume all the knowledge they learn about other people is a gift from God that can be used to persuade others that God exists and loves them. However people without a strong sense of calling (like the Bill Murray character, who hated his job) will have to go through more trial and error. Such a person could become almost anything, but their temperament, likes and dislikes will steer them toward something that interests them. That is why self-understanding is the most important first goal. Does the effect of exercise or physical activity persist? Can a person become ready for a marathon? The Bill Murray character learned how to play piano. This required conditioning his hands and fingers, not just learning theory. So how much physical training can they engage in that will persist across the days? This will limit which activities are beneficial. Cyber Security! With perseverance, one could break into most computer systems in the world from a public terminal. One could learn these skills and obtain information from our nation's enemies, organized crime syndicates, corrupt politicians, etc, then anonymously release it to the right places to maximize the benefit to law and order, international peace, etc. Find Missing Persons You could perform an exhaustive search within several hours' travel radius and find all kidnapped people, enslaved immigrants, drug factories, etc. To avoid personal danger, you call in tips and study the police response to see if any criminals were found. This would yield one significant, one time benefit. [Answer] Call the local high school physics teacher and convince them of what's going on. Have them contact the closest quantum physicists and convince them as well. Have them organize a global internet forum of world-class quantum physicists to discuss the opportunity. Have each forum attendee provide one intimate secret which the looper can memorize, streamlining the process of gathering forum participants during subsequent loops. "Hi Mr. Kaku, Thank you for speaking to me. I am a time traveler and as proof of that claim, later today, you will tell me that your mother's eyes were green. Please call the following conference phone number to join the discussion. Bye." Time loops are extremely rare. As far as any of us know, none have occurred since the birth of science. Giving the task of optimizing a timeloop opportunity to the strongest minds on the planet, is the best way to maximize its positive effect. The tests they would devise and have the looper perform at the end of each passing iteration, would illuminate the otherwise unperceivable nature of time, allowing our science to advance dramatically. Yes... I stole this answer from Stargate, but they stole it from Bill Murray, so... [Answer] ## Blockchain your way to victory. Do insider-trading/fortunetelling on anything that will get you money before the day is out. Stock-trading sometimes has 3-day limits on getting you the proceeds, so that may be out. It might be scratchers lottery tickets at $600 a pop. Get the money as soon as possible during the day, and start purchasing computing power to do blockchains on cryptocurrency. Digits are small, and worth memorizing. As soon as you have enough in cryptocurrency, the next day you can start spending that to buy computing power, to make further gains in the blockchains. You can also start making that money and renting machines and such, virtually, and at any point in the day (12:05:AM, then roll over and go back to sleep) Money will help you do the other things that you need to get done. ## Get the smartest people to help Similar to @HenryTaylor's answer (but not quantum physicists). ie: Get the smartest people in the world to help you figure out what could/should be done (Gee, what's this site doing?). Not a problem for personal safety, you have a good escape and evasion plan (or start a separate forum for increasing your skills in that) that only needs to take you long enough to reach the reset point (ie: go to bed early). Then you only add one or two people a day to the forum. If someone starts hunting you that day, you likely know who the problem was, and/or can stop at the prior level of involvement and start investigating who was hunting you, and how the interaction between prior involved people was causing this to happen. In any case, when you select your exit-day, obviously you don't set up a forum that day, and none of them know that they helped you. Btw, mother's eye color and SSN are particularly bad questions for this. Either is learnable by thorough investigation of a target. If someone called you up out of the blue and told you they knew your mother's eye color, would you conclude that they're a time-traveler, or would you suspect a prank or someone who knew you/your mom? I'd call them on their personal unlisted phone number, at 1:AM; and (on first iteration: ask them to write down what they're thinking/pick a random word or phrase/number), then tell them that (on the next iteration). Might be best to use a text-to-speech application, to prevent tone, inflection and spacing of the words from causing any unforeseen variation in their selection of something random. Anyone who lies, can be told they're thinking of lying the first time, and to do it correctly. ## Get EVERYONE to help If you want the whole world to work on the problem of what's most useful to do, you can release information on future micro-quakes publicly, then alert reporters who you've dug up personal information/blackmail on to report widely. Then you can get started by brain-storming on a wikipedia page (or some high-traffic site; blackmail a google executive into hosting, if they don't believe). You could also pay each reporter to go purchase scratchers tickets from a location (on first iteration) until you tell them how many tickets down they need to go, and in what pattern to scratch to pull in actual money - if you want a surefire way to get a lot of publicity. You can also work on winnowing down to the most useful/connected people you need to reach first. Who can convince the most with the least effort. Then you can spend less time on convincing people and more time on memorizing the things that need to be memorized. You might want to convince George Soros or Bill Gates. Call them up on their private phones. Then maybe providing them some stock market data, and convincing them to give you passwords to one of their existing (or just created) portfolios. Then tell them to spend a billion dollars and get some shi...stuff moving. ## The problem with big lotteries Winning a big lottery is going to be a problem - they typically don't hand you the cash the same day (numbers are often pulled after working hours/there's still paperwork to do). So you're not going to be able to know which ones are going to get you investigated and which ones are not, or what the threshold of "winning too many" is (consequences may take days to manifest). You also have the problem of getting the tickets purchased (time/space constraints); but taskrabbit and the like make this much easier. Of course that may ruin your non-publicity status, as if more than one taskrabbit publicly comments that they purchased a winning lottery ticket for an anonymous someone in [place]... a reporter might take note of it. Have you tried to buy a lottery ticket from Europe? Or from a state or two away on the other side of the Mississippi? ## Actual suggestions Of course, those are some smart ways of doing the actual thing. Writing some fiction means that your protagonist is going to end up with some actual suggestions, which you're going to need.... here's some: Once you've got money, you can also post hacker-challenges: Find a bug within 12-20 hours, and win a million bitcoin. Done right after you release all the bug-fixes from the prior iteration. Any task-intensive search project: Have each researcher break it up into one day search chunks, and then tell them which day they should search on for each iteration (which will also help you keep sane, and track of how many days you've spent doing shit). All you need to do is remember which day the successful solution was found on for each project. Conversely, you can even prevent local optimum solutions, and find global optimum solutions by traversing the whole search-space, even if you find a pretty good candidate early on. Say, SETI or astronomical searches. Gene therapy research. [Answer] The easiest way to do good is with giant piles of cash. Memorize every horse race, every match, every game, every lottery that happens that day. Practice setting up all the accounts you need as fast as possible. Many of them pay out fast. Dump all of your savings into every chained-bet possible, particularly the long odds bets or ones with jackpots. Sure, it will probably be noticed but there's no explicit laws against time travel. End the loop and dump your tens of millions of dollars into the most effective charities you can find. (remember, the marginal cost of saving a human life is between \$1000 and \$4000 so you can save far more lives than the character in groundhog day) Pay any taxes due, move somewhere out of the way and pay an actor to pretend to be you if anyone from the media comes looking for "that guy who won all that money". ]
[Question] [ Background story: In near future (max 10 years from now) mega-rich person suffers yet unknown disease. He obviously employs every doctor possible and spends loads from his fortune on researching, what is wrong with them. The scientists come up with some time-delaying solution: Such disease has little or almost no progress, if a patient is in microgravity (= very close to zero gravity). Our hero has now to decide. To die with 90% probability in one year, or, buy a ticket to ISS and stay here for some time and hope for the best. But he could be stuck there forever... The question: Is such disease plausible? And ultimately, even if its on verge on implausibility, what symptoms should such disease have? How to make it more plausible? [Answer] Such a disease is definitely plausible. Human physiology is heavily influenced by gravity in many ways, none of which we fully understand. It's entirely reasonable to propose that microgravity could prevent the progression of a disease. As an example, [Fibrodysplasia ossificans progressiva](http://en.wikipedia.org/wiki/Fibrodysplasia_ossificans_progressiva) is a rare, inherited condition of excessive, improper bone growth. Essentially, whenever the body is wounded, bone is grown at the wound instead of normal tissue. The result is that the patient slowly turns to bone. Surgical procedures to remove the bone only make things worse as the body heals the incisions with more bone growth. There is no known treatment or cure. Now, bone loss is a major issue for astronauts spending prolonged periods of time in space. Part of the problem is likely the reduced requirement for the muscles and bones to hold the weight of the body, but some [researchers](http://science.nasa.gov/science-news/science-at-nasa/2001/ast01oct_1/) think there may be molecular mechanisms governing bone growth that are sensitive to the gravity and don't work in space. Potentially a microgravity environment could inhibit further bone growth. There are many things we don't know about microgravity's effects on our body, so I think it is definitely possible that Fibrodysplasia ossificans progressiva could be helped by a microgravity environment. [Answer] The disease needn't be a virus -- it could be a larger parasite organism attacking the host. Once you've established that the person is under attack from a parasite, all you need is to invent a creature that dies in zero gravity. For example, human immune cells can't mature in zero gravity. A creature whose cells needed to be regrown more frequently than ours might not be able to survive long in such an environment. [Answer] Malignant obesity hypoventilation syndrome. from [A case report of malignant obesity hypoventilation syndrome: A weighty problem in our ICUs](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5126148/) > > CASE PRESENTATION: 35 year old African American gentleman with a body > mass index (BMI) of 115 kg/m2 presented to the hospital with > respiratory distress. On admission he was noted to have multi-organ > dysfunction including respiratory failure, renal failure, cardiac and > liver abnormalities. His hospital course was remarkable for recurrent > cardiac arrest following extubation, complicated tracheostomy, and > progressive organ failure despite medical therapy. After a 30 day > hospitalization, patient and family decided on terminal extubation > owing to worsening medical condition and lack of therapeutic and > disposition options. DISCUSSION: The super obese present a number of > challenges when admitted to the ICU. Patients with respiratory > distress are frequently misdiagnosed and treated for asthma and COPD > when obesity hypoventilation syndrome (OHS) is more consistent with > the clinical picture. OHS in the superobese is often accompanied by > multi-system organ dysfunction, a condition with high morbidity and > mortality, with limited treatment options. > > > From the article; this man was 182 cm, 383 kg (844 lbs). The weight of the body crushes the lungs and makes it more and more difficult to breathe. It is much the same situation as marine mammals which are on land and do not have the water to support them. In zero-G this mega-rich person would not have to move the weight of his body while breathing. He would probably feel great. While writing this I was thinking of [Iz](https://en.wikipedia.org/wiki/Israel_Kamakawiwo%CA%BBole) who died of complications of obesity. I bet the water made it easier for him. Too bad he did not have a space station. [![Bruddah Iz](https://i.stack.imgur.com/QLJrg.jpg)](https://i.stack.imgur.com/QLJrg.jpg) [Answer] To get use of such low gravity, person with that rare disease needs to survive * the stress of astronaut training (which might be a challenge - presumably rich person would not bother if he was in good enough shape) * the high-G stress of launch. Contradiction in requirements. [Wikipedia says](http://en.wikipedia.org/wiki/G-force#Typical_examples_of_g-force) that Shuttle had 3G acceleration, which is LESS than high-G roller-coaster. So I guess it should be safe enough (survivable) to launch him up using shuttle, with some risk. [NASA article about acceleration](http://quest.nasa.gov/saturn/qa/new/Effects_of_speed_and_acceleration_on_the_body.txt) says: "The human body can tolerate violent accelerations for short periods, including the the prolonged high-g acceleration necessary to reach Earth orbit." ..."Heavy acceleration is a speeded-up aging process. Tissues break down, capillaries break down and the heart has to do many times its proper work." So answer is like always it depends - in big part on what kind of (undefined) launch vehicle you plan to use. The gentler the better. Now you have framework to ask for more questions to make your story more plausible. ]
[Question] [ I have an alien I am designing and I want there to be an individual to be a play off of my main character (who is albino.) The aliens are, unknown to the human settlers, an enigmatically intelligent species, capable of using chromatophores to communicate with one another. They are black and mottled at rest and have limited muscles to change their skin texture. As they are very cleverly camouflaged, I want the alien that accompanies my main character to be easily captured, and to match my main character. I've searched through a lot of research but can't find anything about albino octopi. I assume they don't exist, die early, or just aren't recognizable to us as albino. So, a) What is the feasibility of there being an "albino" in a species that uses color to communicate, and b) Would they still maintain their chromatophores to camouflage when out of rest (not engaging chromotophores)? and c) Could they lack their primary pigment at homeostasis and maintain their communication mode? These are the issues/questions I boil it down too. Please try to be kind in the replies. I am not a scientist and I am willing to learn. I am also willing to clarify if need be. Thank you! [Answer] # Go For It: None of this is terribly difficult to justify for any species, let alone aliens. Biology has so much diversity in it that you can pretty much make an alien albino have any qualities that your story requires. I've worked a bit in albinism research, and there's a lot more diversity than people think. From a strict perspective, an albino lacks the expression of eumelanin during development. It surprises most people to learn that there are brown haired, brown eyed albinos (especially in the Amish community) who are only defined as albinos because they have vision problems. Lack of eumelanin during development causes abnormalities in foveal development and the poor vision associated with albinism. The genes can turn on later, resulting in normal appearance. So your albino alien could have any number of problems as a side effect of being albino. Since they communicate with chromophores, it might have the equivalent of a speech impediment (it can't make the visual version of an "s" sound, for example). It could have visual abnormalities that mean it can't see clearly at a distance and thus is easy to capture. It could be that camouflage is instinctive, but this individual can't get the colors right and stands out like a sore thumb. But most intelligent species would compensate for disabilities amongst them (unless it helps your plot) and adapt language like braille or sign language among humans. This means your individual may be used to a non-standard communication style that opens up the opportunity to learn or teach "speech" to humans. Imagine, for example, they use colored cards to signal messages. Humans might not recognize chromophoric speech right away, but flash cards are more apparent. [Answer] Albinism is caused by the lack of a single pigment, and can be caused by a single mutation in any of seven genes. Consequently, your alien would need to have two kinds of pigments: those that cause it to be black and mottled, and those in the chromatophores. Ideally, there would be one pigment in the first set, thus simplifying the task of removing it. But as long as the pigment sets are distinct, your albino could communicate with chromatophores. On the other hand, unless the chromatophores are normally active in the camouflage, it is unlikely that the albino could use its for that purpose, unless it used them deliberately by developing abnormal usage. Normal usage would mean their rest color was in part derived from the chromatophores and consequently you could not have an albino who could speak using chromatophores. ]
[Question] [ Storm fronts — especially surprise storm fronts — are a popular Sci-Fi trope. Ion storms and radiation storms and neutronic storms and they invariably look 2D, like ribbons in space. But then I read [this article](https://www.sciencedaily.com/releases/2016/04/160406133622.htm) about nearby supernovas millions of years ago that showered our planet with radioactive debris and remembered that we've seen the increase in light as the photons from these massive explosions arrived at our planet. And it got me wondering — how many such "wave fronts" might exist out there that we don't know about because the light hasn't reached us yet1 and how might that affect space travel? So... * Given that we're using technology only moderately better than today's space shuttles, save that we have engines that let us move the intragalactic mail.2 * Given that we do not have electromagnetic shielding (whatever solid material known to humanity today that rests between the crew and the vacuum of space is all we have to work with). * Given that those wave fronts (aka, "storms") are spherical in nature.3 * Accepting the fact that some storms emanated from very distant explosions while others are much "younger" in nature.4 * And noting that a "navigational hazard" is anything from interfering with the ship's electronics to killing the crew. Question: Do these natural storms in space pose, on average, enough risk to our intrepid crew that they represent viable navigational hazards deserving of being charted and monitored? --- 1 Or that have already passed us. Ships leaving our system would eventually catch up to the storm fronts that affected our planet millions of years ago — from the back side. Some fronts chase us, others we chase. 2 On a galactic scale, we've moved through space not at all at an inconsequential crawl. When we start moving vast distances at near-c/FTL speeds, we might discover storms like this are as common as rain. I'm certainly no expert on the Sci-Fi front (I read as much as I can, but I wouldn't dare claim to have read more than a fraction of what's out there), but I've never encountered this idea before in the literature. Has anyone? 3 Though supernovas are obviously the most likely candidates for a true "storm in space" representing a trackable navigational hazard, the ejecta from a number of objects may be as big a deal in different ways. For example, a supernova creates a spherical shell of matter and radiation that increases forever but has a definable thickness, a pulsar has a less dramatic output that's a constant flow, a conical stream in 3D. 4 The most dramatic storm I can think of would be the explosion of a galactic core black hole. I have no idea if this is even theoretically possible, but let's run with it. While such an explosion would be spherical in nature (and dangerous in its own right), it would also be strong enough to push the planets (both destroyed and intact) of the galaxy outward in an ever-expanding band (combined with their existing motion, the expansion would be reminiscent of pouring paint on a spinning board). That's as close to a 2D storm front as I can get, and the natural rate of expansion would probably make it no different than any other storm front the ship encountered. But it's cool to think about. [Answer] The answer to your question depends strongly on the supernova rate in the galaxy. The Milky Way is current not undergoing an episode of significant star formation; therefore, it isn't producing an extreme amount of massive stars and, by extension, supernovae. Energetic events like gamma-ray bursts and kilonovae are not expected to occur at high rates in our galaxy, either (one GRB every [100,000 to 1,000,000 years](http://www.astro.sunysb.edu/lattimer/AST301/lecture_grb.pdf) and one kilonova [every 10,000 to 100,000 years](https://arxiv.org/pdf/1809.04295.pdf)). Therefore, we care mainly about the rates of core collapse supernovae. This turns out to be much easier said than done. Thanks to various observational difficulties, we have yet to tightly constrain the supernova rate. Astronomers are confident in the value to within a factor of a few; typical measurements indicate values of 3-5 supernovae per century (see e.g. [Hakobyan et al. 2011](http://adsabs.harvard.edu/abs/2011arXiv1104.0300H)), so I'll go with that value. Let's look at how [a supernova shock wave](http://www.astronomy.ohio-state.edu/~ryden/ast825/ch5-6.pdf) - the "storm front" we're concerned with - evolves over time. There are three phases to its life before it merges with the interstellar medium: 1. Free expansion. The shock has a roughly constant velocity (usually a few thousand kilometers per second) and therefore increases in radius linearly with time. This period lasts for about 500 years. 2. Blast wave phase/Sedov-Taylor phase. Now the shock undergoes adiabatic cooling, and begins to slow down. The velocity scales with time as $v(t)\propto t^{-3/5}$ and the radius scales as $r(t)\propto t^{2/5}$. The shock behaves like this for several tens of thousands of years. 3. Snowplow phase. Eventually, radiative losses become dominant and the Sedov-Taylor solution is no longer valid. A dense shell forms behind the shock, sweeping up matter in the interstellar medium as it expands. We have $v(t)\propto t^{-3/4}$ and $r(t)\propto t^{1/4}$, indicating that the shock is slowing down even quicker. We expect the snowplow phase to end after about one million years, when the speed of expansion drops to the speed of sound in the interstellar medium. This is an approximation; there are a number of things that can cause some deviations from the model. For instance: * Asymmetric ejecta would cause departure from a spherical remnant. This is important during the free expansion phase, where the swept-up matter is less massive than the ejecta from the explosion. * Supernovae, especially those occurring in star formation regions, may exist inside superbubbles caused either by previous remnants or winds from massive stars. This, too, will have effects on the remnant's expansion. Nevertheless, the normal expansion-blastwave-snowplow model is sufficient in the vast majority of cases. We're only looking for a simple approximation. Our analysis indicates that the existing supernova remnants in the galaxy should be less than about $\sim10^5$ years old. If they form at a rate of 3 per century, there should be about 3,000 still around - most currently in the snowplow phase, the longest of the three periods. Given that the galactic disk is about 100,000 light-years across, this comes out to a surface density of $3.82\times10^{-7}$ per square light-year, and the nearest one should be, on average, about 1600 light-years away. Keep in mind, though, that these remnants are big. By the end of the snowplow phase, they may have radii of 100-200 light-years. That said, at that point in time, the shock waves are vanishing into the interstellar medium, and really aren't much of a threat. Earlier on in that phase, though, the shocks can be dangerous, with temperatures and densities in the expanding snowplow shells of $T\sim10^6\text{ K}$ and $n\sim10\text{ cm}^{-3}$ in the worst-case scenario ([Cioffi et al. 1988](http://adsabs.harvard.edu/abs/1988ApJ...334..252C)). Interestingly enough, these properties make the shock similar to the solar wind as experienced at Earth's orbital radius. We should expect to see cosmic ray and x-ray emission from the hot gas, especially during the Sedov-Taylor phase (see [Vink 2012](https://arxiv.org/abs/1112.0576), which is actually a really good resource on supernova remnants in general), and I do imagine that this could pose a separate threat to any spacecraft in the vicinity. Turns out that if you heat up gas to $\sim10^7\text{ K}$ ($kT\_e\sim1\text{ keV}$, for reference) and send shock waves through it, you get strong x-ray emission! The emission should take several forms: * Thermal x-rays caused by free-free and bound-free emission in the optically thing plasma * Line emission, both from collisional excitation and radioactivity * Non-thermal emission, including x-ray synchrotron radiation and non-thermal bremsstrahlung Fortunately for us, some of this strong emission should only occur in young supernova remnants - not those in the snowplow phase. That said, essentially all remnants which have not cooled down to temperatures comparable to that of the interstellar medium are still going to be strong x-ray sources. I would recommend avoiding them. Now, is the expanding shock wave enough to pose a danger to a traveling spacecraft? Perhaps; unlike Earth, a spacecraft has no magnetic field to shield it from the shock. However, I suspect that shocks in the snowplow phase are usually not hot or dense enough to produce cataclysmic effects. There are certainly some supernova remnants that are young and hot and could indeed be dangerous, and from this point of view, it does make sense to map out these potential dangers. That said, keep in mind that these remnants are, on average, over 1000 light-years apart, and it should be easy enough to avoid them. [Answer] Barring a 'physics surprise' of something we haven't yet observed, then 'space storms' are unlikely to be too great of a risk to interstellar vessels simply on the basis that anyone who can build such a vehicle is probably going to want to build them to handle the levels of radiation we have seen from such sources. At this time I am not aware of any observed emission of a power level that could not be overcome with current or near future materials and tech, and our primary limiting factor lies more in infrastructure and energy tech. - That is, we could design a ship currently, but lack the means to gather the resources in a manner that actually makes any remotely economic sense. Physics and engineering might make use of 'bolt holes' and limiting crew space volume during some periods, to help ensure proper shielding against elevated levels, but I'm not aware of any deep space energy waves having been detected that could 'throw a ship about'. Keep in mind the effects of the Inverse Square Law - The further you are from something, the lower the energy that reaches you. Which gives us two counter points to keep in mind: 1. Effects which generate focused energy, that may effectively remain stronger at longer ranges. [and cover narrow regions] 2. Effects that take place while you are close to the generation source. Solar flares in inter-planetary space are going to be far more noticeable, and potentially highly dangerous, while in a solar system, but be far less of an impact mid way between two independent stars. There does stand the potential for a risk similar to 'rogue waves' in the ocean, where lots of frequencies from countless sources make a sudden energy peak in a highly localized area, but I'm not aware of any hard science that such a thing has ever been detected in reality beyond a mathematical model. - But that would be like a ship hitting a mine, and over and done with in a flash. [Answer] Here's my take on the issue of charting 'anomalies'... 1) They're plentiful 2) They move 3) They can be ephemeral 4) The highest risk is more from the things that have just happened, like supernovae To put this in context, there are [several papers](https://www.sciencemag.org/news/2007/08/cosmic-rays-and-dangerous-days) available on the theory that one of the major causes of extinction events on the earth is related to its orbital 'wobble', that is to say that the Sun travels up and down along the galaxy's orbital disc in its orbit around the galactic core, and that every time it passes through that disc something happens through the sheer proximity of other stars. This is despite the fact that the relative location of the Sun in the orbit is very sparsely populated. If you consider the implications of this, then the primary risk you face in space is being close to... well, pretty much anything. In that regard, the better solution is protection rather than charting per se. Charting would require constant maintenance insofar as you have to track the threats in real time, not only in relation to their own wobbly orbits, but also in terms of their efficacy, decline, sudden emergence... That's a lot to track and you'd be lucky by the time you get all that in a real time navigational program if it let you cross to the other side of the bridge. So; how does one deal with the nature of space storms and debris? One of the best solutions I ever read came from Arthur C Clarke (who else?) in his book [Songs of a Distant Earth](https://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth) in which he designed a sublight space ship that had hundreds of metres of ice on the front end as a kinetic shield for dust debris and the like. I'd argue that this would also solve most of the problems of radiation storms et al because the ice would either block or absorb most of that if it's in the path and the only risk you still face is a super nova going off right beside you, throwing a massive lateral flare or storm front your way. For most of what you describe however, the threat is in front of you so the best solution is going to be a shield, and an ice shield as Dr Clarke described is actually one of the most practical solutions to the threats of space at speed that I've ever come across in my reading. There are some threats that it will be important to chart in the future; black holes, nebulae, suns that we think are at risk of going nova, etc. Being somewhere else when these things are around is always a good idea and as such, we need to know about them in advance of our trip. But, I suspect that the charting of these things will be relatively high level, and that the day to day things in space that can kill us just as dead are better deflected than avoided, especially given that many of them won't be on our radar (so to speak) until the first accident. [Answer] 1) Ion storms would not exist other than a solar flare, and we do have a way to shield against it. <https://chemistry.stackexchange.com/questions/94514/can-gas-be-made-to-block-radiation-better> 2) During Interstellar sublight space travel a flight path would be plotted around and away from any star that might cause an Ion storm. 3)This is on topic for Space.SE. ]
[Question] [ So... I've been playing a lot of the video game Subnautica lately, which put me in the mood for a "trying to cope with being marooned on an alien planet" sort of story; however, there's something in the game that's made me wonder about the logistics of a particular problem. At one point in the game, you don a Radiation Suit and return to the crashed remains of your former spaceship in order to contain the radiation leak from when the FTL Drive Core blew up post-crash and keep it from spreading any further; while you're there, you discover that some parts of the ship are still surprisingly intact, including some of the crew quarters, and you can scavenge and collect various items for use in your own "base camp", including components for new technologies. In addition, you can also collect various decorative items that presumably belonged to the ship's late crew members, such as a model spaceship and a large plush toy. This inspired me to include a scene of someone attempting similar containment of radiation from a crashed vessel discovering that some items belonging to a fellow officer's children - who survived the crash and who are now obviously feeling distressed and afraid back at the group's temporary shelter - and decides to bring the toys back to camp with them to return some sense of normalcy to the children's lives. However, given their close proximity to a large and presumably nuclear explosion and the continued leakage of radioactivity into the surrounding ocean, could something like a plastic model ship or a soft cloth toy be safely cleansed of radiation? Some details about the explosion that might be useful: * Here’s some footage of the actual explosion and the description your PDA gives you, I’m not 100% sure if anyone can discern anything from this but I thought I’d include it anyway: <https://youtu.be/rIlxEJG5whU> * The ship seems to use a lot of titanium, according to some flavor text on one of the equipment pieces * The crash took place on an ocean planet, and so the remainder of the ship was partially submerged in a large body of water (I think I remember learning something about water affecting the spread of radiation differently than air? Please correct me if I'm wrong about that). For the purposes of making this easier, let's say our marooned group also crashed their ship into a sizable body of water * The actual compromised "Drive Core" was underwater, while the portion of the ship where the relatively intact crew quarters were was still above water and, if I remember correctly, positioned a few floors up and at the opposite end of the wreckage, so the objects in question likely never came into contact with any material leaking from the drive core post-explosion, if that matters? The crew quarters also still seemed to be sealed for the most part. * I'm not sure what the Drive Core was made of or how it worked (the game gives you some technobabble about a "Dark-matter ion drive core", whatever that means), but it seems like there was at least some uranium involved, as a lot of the other nuclear-powered tech options in the game use it, so that's probably a good basis for what sort of thing we're dealing with here * These items are being retrieved somewhere between 24 hours and 2.5 weeks after the initial explosion/event; exactly when in that window may depend on the answer to this question So, with the above parameters in mind, here is my question: Would this kindhearted gesture be possible without horribly irradiating the Kids? Or would the would-be hero have to leave the toys behind due to health risks? In fact, while we're on the subject, could your character in the GAME safely repurpose these items? Or is he going to survive the crash, the unforgiving elements, and the hostile alien wildlife, only to succumb to unexpected radiation poisoning? [Answer] I think you could do it. Stuff that is irradiated with electromagnetic radiation (like X-rays or gamma rays) does not generally become radioactive. That is how they can use radiation to preserve food. If you see fresh (plastic wrapped) meat for sale with an expiration date a month+ out you can assume it has been irradiated. It might not say on the label. Fallout, though, is different. It is dust swept up in an explosion and contaminated with fission products. These are radioactive in all the different ways, and some isotopes could be strong enough to induce radioactivity in normal materials in the dust via particle radiation. Nuclear fallout from a bomb loses potency pretty fast. <https://en.wikipedia.org/wiki/Nuclear_fallout> > > The danger of radiation from fallout also decreases rapidly with > time due in large part to the exponential decay of the individual > radionuclides. A book by Cresson H. Kearny presents data showing that > for the first few days after the explosion, the radiation dose rate is > reduced by a factor of ten for every seven-fold increase in the number > of hours since the explosion. He presents data showing that "it takes > about seven times as long for the dose rate to decay from 1000 > roentgens per hour (1000 R/hr) to 10 R/hr (48 hours) as to decay from > 1000 R/hr to 100 R/hr (7 hours)."[30] This is a fairly rough rule of > thumb based on observed data, not a precise relation. > > > So if your toys were contaminated by dust produced in a similar explosion they too would lose potency pretty fast. I think you could give saving them a shot. If you get the dust off that might be enough. Wash the plushy well with soap and water. Wipe the plastic thing off. Use a detector and see if they are still radioactive. If so, try it again. If still radioactive, wrap them up and set them aside (not under your pillow), then check them again a couple of months later. ]
[Question] [ I am still working on my intelligent detrivore alien species and so far I have gotten some great help from you guys. But after searching online a lot about detrivore psychology I still cannot find anything to help me so I go here. And my question is: what kind of psychological differences from a human could you expect in an intelligent, detrivore species? Based on the fact that y’all need more info and I am very happy to give it to y’all, here is an info dump of everything I have developed so far... * Physiology [![sketch of the detrivore's anatomy - hope it doesn't look too gross](https://i.stack.imgur.com/e8P13.jpg)](https://i.stack.imgur.com/e8P13.jpg) ### Planet The planet has about 20% less gravity than earth, a much hotter and more radioactive core, and stronger electromagnetic field(on the surface about 2.55 Gauss). It also orbits a dwarf star, so other than that it is very similar to earth. ### Ecosystem Most of the ecosystems on the planet are thick forests, but not like an earth forest as the tallest autotrophs are called the ZXyphernics and they look like super tall(about 500-1,000 feet) pail blue mushrooms with multiple stems(30-50 per ZXyphernic). They absorb most of the light so it is dark below them, but not too dark so you can’t see(think of the nigh time with a full moon). The other autotrophs have adopted a clever strategy and now instead of photosynthesis they use a made up process I call it thermalsythesis, it is basically the autotroph sucking up heat with its dermal layer that contains ethylene glycol saturated cells. If you're wondering where all the heat comes from on an earth-like planet well I got your answer. Their are vents all over the plants surface that give off a lot of heat and carbon dioxide (fun fact: if you go deep enough into the vents you can find super critical carbon dioxide). Now for the major consumers on the planet, well their are super sized herbivores(for common size think of the titanosaur) and the predators are small, fast, strong, mean, and work in packs. ### Diet This one should be obvious cause because detrivore is in the title, but I will go into more specifics about the specifics and maybe answer the question of why they stay detrivores. So basically the ethylene glycol has a similar effect to how cow’s milk reacts with human digestion. The giant herbivores cannot digest all the nutrients in the plants and can only get some because the ethylene glycol in them block some nutrients from getting in so the herbivores so they just excrete it. This is where the detrivores come and get their energy, they evolved the very rare ability to separate ethylene glycol from the nutrients and eat the poop of the herbivores as an easy food source. But this separation takes energy and they aren’t just gonna waste a perfectly good PCM like ethylene glycol so instead of just excreting it they use it in their own biology and mimic the thermalsythesis of the bottom autotrophs. They now have energy from two sources and can now support a big brain. Now for why they have these big brains, well the floor ps of the planet are covered in detritus, yes, but the detritus isn’t very nutritious and what they want is the herbivore poop. But their is a problem, to avoid being tracked by the predators the herbivores adopted congregational pooping habits(similar to the hyrax) and where changes very frequently even in the basis that one herbivore is slightly nervous. So to get this poop you need to have a great long term memory and super advanced eyesight, leading to an advanced brain. And to evade or overcome predators they need to clever and have abstract though with great problem solving skills. ### Breeding They breed parasitically, and to understand why you need to understand yes they may be in the minority for it but do it is as old as the lymbic system is for earth creatures. Most of the consumers on the planet don’t but that’s simply because they are as different from the other consumers as fungi is from plants and split off very early from each other in their evolutionary history. And the system never hurt them and was energy efficient so why change it? It’s a lot like angler fish but with the genders reversed and the brains don’t eventually dissolve in the female but they meld. And don’t worry the females aren’t intelligent until they meld with the males. ### Life Cycle They all start out as small goop blots that are about the size of a quarter, and then grow really fast after the third day of their birth and the females stop after day 8. The males start puberty at 2 years old and the females never go though this puberty (think Osedax with the genders reversed) and then the males grow even bigger and gain all the stuff they will need to make babies. After 17 years of this they are finished and adults, and live another 110 years on average. ### Culture I haven’t gotten to this one much or gotten very details because I wanted to design it after their psychology. But what I have is so far is an idea of cast system and it is signaled by how you commute. They tend to be very individualistic and touch and interact with each other more than a person on ecstasy. ### Child Care When born all the larva are placed into pairs alone into holes for two days to bond, then on day three all the pairs are shoved into a very large hole for two hours without supervision, and in these two hours, lets just say all of the larva start out as hermaphrodites and by the end of two hours, all but one pair are female and the and the still hermaphroditic pair, are taken by some adults and made to be male. At day eight the females will have been fully developed and fuse with some males, and the males are raised for 17 years by the group, kinda like Capybaras. ### Society uhh basically a rigid cast system based on 17 year gaps between the generations, having kids outside of this will have you killed and your child kick outside of the clan. You gather your own food(poop) and give a portion to the oldest generation, as they are looked on as feeble and foolish. They are kept out of respect and love more than for any practical reasons. They are also a theocracy, that's all i got sorry... ### Language Quick membrane color flashes and color changes(microwaves to UV light) along with hisses and that's about it. [Answer] As with all species, the psychological features depend greatly on the enviroment and on the food available. So for the most part the answer is : It is up to you. You will need to further define the social life (for example what kind of structures they build/live in), the evolution of social structures (are/were they Nomads, when did changes happen) etc. Enviroment is a factor because based on landscape , competition and other attributes of the biome, other attributes will be evolved. This is not confined to physical attributes but also to psychological attributes as the brain evolves in vastly different ways. (A good example are the different brains in human subspecies which lived during the same era, but in different enviroments) The food is important too, because the ingredients are one of the main factors for the features the brain can develop. Therefore directly impacting the abilities of the species. Including social structures and the ability to think in more complex ways. There are some things that can be assumed : due to the lack of arms and legs the part of the brain that is responsible for movement is probably underdeveloped compared to humans. The existence of three eyes would result in : a) a more developed region of the brain for optical inputs. b) less developed eyes (for example less colors and/or a lower 'resolution') Tl:dr the physiological aspects have a great impact on the psychological impact of a species, therefore nobody can accurately depict the psychology of a creature without direct observation and/or and accurate description of enviroment, social life, physiological traits etc. Since there are no intelligent detrivores on earth (I assume this is because of lower energy and nutrient gains from their food compared to other food types) there are no comparisons available. Either you a) come up with alot more details than you have already provided. Or b) you take the reverse route, come up with the psychological traits you want and ask a new question to get information on how these are achievable. Note that you will need to provide alot of information for the second aproach too (since you are developing a whole new alien world we need to know the conditions). The benefit of the second aproach is that, as a response you will (hopefully) get multiple possibilities, from which you can take the one that fits your world the most. [Answer] Apart from the mating factors, what these creatures most seem to represent is elephants. Nutrients are sparsely located in specific places, based on the routes of migratory herds. While the leader of the herd knows the way to many such locations, the younger members haven't yet learned the way so they follow the leader, learning as they go. In bad years they travel more widely, visiting sites that are normally far out of the way, and only known to the oldest members of the group. So elephants culture is where you may want to go with this rather than comparing them to humans. Tightly knit, nomadic, highly social and intelligent, led by a matriarch, in your case a patriarch who knows the way to the water/food sources in bad years. You'll need to work out some way to transfer genetic material between groups, which will be a key part of their social structure. [Answer] It might be helpful to consider the range of psychology that already exists within closely related species. Bonobos and chimpanzees, for example, are both highly intelligent, tool using, jungle dwelling apes that are close relatives. They occupy very similar ecosystem niches. But slight differences in food abundance led to stark psychological differences. Bonobos are egalitarian, polyamorous, nonaggressive, and generous. Chimps are aggressive; they wage war, kill and eat each other. EDIT: added the below There is a pretty intense debate about how this divergence came to be. One popular argument is that food scarcity in the evolutionary past of chimps led them to be more aggressive; bonobos are friendlier because they can afford it. This is not universally accepted, however. More food can also just mean a larger population, which would then lead to less food. An alternative explanation is that a species can became aggressive by ending up in a prisoner's dilemma feedback loops: one group of individuals became aggressive by chance, and now no one can start being nice without getting punished for it. Aggression is costly, however: it diverts energy towards managing endogenous threats that could otherwise be spend on exogenous threats. If a species were designed by an engineer rather than evolution, I'm willing to bet it would be a cooperative one. Compare the selfishness that leads to human traffic jams to the efficiency of an ant colony's swift and organized march. Note that when I say "cooperative and friendly", I mean towards other members of your species. Orcas are very cooperative and friendly with each other while taking great pleasure in literally torturing seals to death. Behavior towards other species is an entirely different topic. In short, there can be a huge spectrum of psychology even within a single ecological niche: bonobos and chimps are incredibly similar in so many ways, but their societies are radically different. I can't think of any reason to think how the information you have currently supplied regarding your detrivore would lock them into any one particular psychology - they could at this point be either bonobo or chimp. I'm not sure I agree with the other comment that physiology is a strong determinant of behavior. If you look up videos of octopus, cuttlefish, and squid social dynamics, you will see a wide spectrum of psychology. Example: cuttlefish and some octopi are very maternal, while squids are often egg scatterers. They're all Cephalopods, and yet the breeding habits of cuttlefish are more similar to goats than squid. Given that, I think you should feel free to first come up with the pyschology you want them to have and then decide what additional ecological/evolutionary impacts you want to add to their background that might have led to that behavior. Perhaps create a new question post with the psychology you would like your creatures to have and we can suggest how they might have gotten that way! [Answer] If females are completely parasitic that only leeches off males without giving anything back to them, they are going to be inherently disliked by the males. And the males can find ways to get rid of the parasites from their body, or even completely avoiding any interaction with the females. So, the males must really like the females, or the two sexes will need to have a little bit of mutual relationship. Since detrivores are smart, they are going to realize that working together is going to increase their chance of survival, which means that they are going to be social creatures. Their social structure is going to be different than humans, though, since they have extremely different physiological characteristic and different developmental stages between the males and females. Detrivores are going to live in groups with male leader, since males are much bigger and stronger. The females in the group are going to compete against each other to get place on the body of the dominant male. Only the best females can copulate with the best male in their group. It's a little weird because the females are going to fuse with the male, which means that technically the male is the one that's going to be pregnant, and not just with one, but multiple babies. This means that male detrivores should have the ability to control the growth of the baby and can absorb the baby back when food is scarce, which is kinda fun. Without this ability, the females with their babies are only going to make him weaker and make him can't maintain his dominance. So, one of the biggest psychological difference between humans and detrivores is how members of one sex see the other. [Answer] I can't see the actual sketch of the creatures for some reason so this is based on the written description. from what you have describe I take it that they are rather defenseless against predators (much like us) so they rely on their creativity. they are probably organised around family's and said family's would inbreed. they are herd animals and they probably farm, and have cattle for the manure and most likely store them in some sort of structure. speaking of structures, they most likely dig shelters into the stems of ZXyphernics (I love that name). [Answer] I think that your aliens would be an egalitarianism tribe. Within the tribe, there is caste ranked by age. From what I understand large litters happen when your alien reproduces. Do the tribe decides to reproduce small litters at one time so to educate the generation better and more quickly? So the litter born is ranked in a caste system in comparison to when other generation where born. Since they are through together then they should be very egalitarian among their own castle and submissive to higher authority, but also commanding of younger generations. Among the tribe, there should be lots a Pearce, and intelligence. With the oldest generation ruling in an aristocratic oligarchy. Through between caste, there is little friction. Between tribes, they can be aggressive really quickly but otherwise are okay if not threatened. They are nomadic and not territorial through it can happen. They are a tight night group they value aid of the group higher than aid of the individual. Tribes do not become too large without losing some of that unity. But otherwise, they are not territorial nomadic peoples who are not aggressive to other tribes unless they feel threatened. There is little friction between caste and the elders have the finale say because they are older. This is just my best guess though. It would help if you would be a little more explicit. Like you imply that they are nomadic but do not secretly state it. You also do not mention what their structures are. You give hints but never say. Please be more explicit. [Answer] Humans tend to be uncomfortable in environments that smell of rot, mold, mildew, decay, and death. Detritovores will tend to be comforted by smells (and other reminders) of other species' deaths. They might (or might not) be discomforted by reminders of deaths in their own families or species. If they are discomforted by reminders of their species' death, it might be due to a chemical signal released by their species' dead bodies that evolved to have this purpose. [Answer] Your description makes it sound like they are very self reliant (since the females seem to offer nothing more than mating upon demand and individuals who aren't old do all of their own food gathering). So you won't have the equivalent of farmers, less specialization and job classification. That would slow technological development much in the same way that big cities on earth didn't evolve until farming did. If these are correct, then their species would be older than ours at the same level of technological development. Depending on what sort of form of history they have (written versus oral versus no sense of history) could change their psychology a lot (cultures with a strong sense of tradition -- a result of a strong emphasis placed on the past/history) tend to be less mutable than others for example. It is hard to give specific suggestions as to how they are different than humans even with all of the information you provided. Knowing what sort of emotions they have would help with an answer. Same with their culture (if they are individualistic then the differences would be similar to the differences between United States culture and say Japanese culture.) ]
[Question] [ Is a planet with varying fields of gravity possible? Yes. Earth has varying gravitational fields at various different times due to various factors, mainly location based. How extreme can I make these varying gravity fields, before the planet becomes uninhabitable? --- The difference between the observed gravity and expected gravity, if the Earth was a perfect sphere, provides us with a handy visual aid of [Gravity Anomaly Maps](https://earthobservatory.nasa.gov/Features/GRACE/page3.php). image below from NASA earth observatory using GRACE. [![GRACE](https://i.stack.imgur.com/EbDYQ.jpg)](https://i.stack.imgur.com/EbDYQ.jpg) The Planetary Society posted an interesting and extremely helpful [blogpost](http://www.planetary.org/blogs/emily-lakdawalla/2012/12110923-grail-results.html) about using results from GRAIL to investigate the gravity anomalies on the Moon. Differences in Earth Gravity are not only just due to location near the equator or the poles. [Interpretations of recent GRACE findings](https://www.newscientist.com/article/dn24068-gravity-map-reveals-earths-extremes) have determined the following: > > The model pinpoints more extreme differences in gravitational acceleration than previously seen. Standard models predict a minimum gravitational acceleration of 9.7803 metres per second squared at the equator and 9.8322 m/s2 at the poles. Hirt’s model pinpoints unexpected locations with more extreme differences. Mount Nevado Huascarán in Peru has the lowest gravitational acceleration, at 9.7639 m/s2, while the highest is at the surface of the Arctic Ocean, at 9.8337 m/s2. > > > However, these anomalies are very VERY small and can only be detected with sensitive machinery. Going to weigh yourself at the top of Mount Nevado Huascarán does not make any discernible difference from your own personal perspective. --- My Question How extreme can I make these gravity field anomalies, before the planet becomes uninhabitable? * before the planet's gravity either starts to equalize through Isostasy and other natural forces, or * possibly tears itself apart * I am hoping that it is possible to have areas of the planet with gravity differences that are noticeable to humans (even if just slightly) and still allow for life to evolve and continue to live on planet. + ie would it be possible to have ~1.1 or ~0.8 g environment in one region and a typical Earth gravity at another, on the same planet, at the same time. --- Answer constraints These gravity anomaly maps are often representative of an average over a period of a month or year of time. For the purposes of this question, using the long-term averages is more than acceptable. Especially as the gravity anomalies are largely due to semi-permanent location factors and not that affected by temporal factors. For reference you can use Earth-like parameters, as I'm building a planet far far away, where normal physics holds sway. I'm also not looking for answers that explain how it would be possible. This question about a [planet with changing gravity](https://worldbuilding.stackexchange.com/questions/18819/a-planet-with-changing-gravity?rq=1) is the closest I could find on SE about what I am after. However it focused on changing gravity fields over a period of time (which would be cool) as well as how to explain how it would be possible. Not on how much actual change would be possible between 2 locations. It was a helpful question but doesn't answer my problem. Most of the 7 pages worth of [gravity] tagged questions were related to adjusting to different gravities, travelling from one to another, or changes over time (mostly centuries) etc. I am aware that there are a lot of factors that influence the gravity anomalies. For the purposes of this question, I am mainly focused on how extreme these variations can be (due to whatever factors) before the planet becomes uninhabitable. Extra constraint: As I am not worried about the 'how', right now, answers are open to terraforming and artificial initial causes. As long as the actual day to day location-based gravity anomalies are following normal physics, don't rely on tech to constantly interfer/stabilise, don't tear the planet apart and the planet is still inhabitable. I don't mind an artificial start to the process. As natural processes will always try to equalize, it may be difficult to have a planet with such weird conditions at such a late stage (life evolution etc). Just need to figure out how extreme these values can be before the natural equalizing processes start to kick in. Obviously answers that rely on an artificial initiating conditions should mention this 'how' factor. [Answer] Habitability has little to do with the ability to achieve orbits. It would have a lot to do with (a) the effects on human physionomy and (b) the ability of the planet to hold itself together. +/- 50 mGal The "average" gravity on earth ~9.8 m/s2 (~32 f/s2) is represented by [1,000 Gal](https://en.wikipedia.org/wiki/Gal_(unit)). The variations demonstrated in your graphic are +/- 50mGal. That must not be very much by definition because we don't feel the variation and the world hasn't experienced the apocalypse (yet..., this is worldbuilding, after all). +/- 1,000 Gal For the moment we'll completely ignore the utter impossibility of a planet with a surface gravity of 0 Gal. However, we certainly would feel a difference between +/- 1,000 Gal (weightlessness vs double-weight). But does that make the world uninhabitable? From a physiological standpoint we're OK. People travel to space and back frequently with no need for a period of readjustment (there may be for the sake of decompression as space suits are at lower pressure than cabin pressure, but that's another issue). From an airplane issue, we're probably OK. Planes would need to compensate for being "heavier" or "lighter" depending on where they are. It would certainly change traditional flight paths as a "lighter" plane would require less fuel, so planes would generally avoid the higher G locations. But, would it tear the world apart? Probably. At the very least we'd be earthquake central, but maybe we're not up to the apocalypse... yet... HOWEVER! We've crossed a threshold. You can't have a planet with a 0 Gal surface gravity. The reality of statistical variation Here's the problem. We live on a globe. Sure, it has globs of lower-density material resulting in lower surface gravity in some locations, and globs of higher-density material resulting in higher surface gravity in other locations. But the reality is, the "average" makes the question of habitability irrelvant. Why? Becuase a planet with so much density, e.g., in the northern hemisphere to be substantially higher than the southern (say, +/- 500 Gal) would tear the planet apart long before life formed. Even if you simply reduce the issue to a bunch of massive super-dense "marbles" within the earth, they'd slop around like loose ball bearings and convert the Earth into a lovely asteroid belt with a few realy dense planetoids. The low statistical variation (+/- 50 mGal) means the Earth wobbles a bit, but it basically spins like a top. But as that variation increases, so does the wobble (as does the inertial forces acting on the regions of high/low density that cause the variations). Earthquakes increase, [dogs and cats begin living together, mass hysteria!](https://www.youtube.com/watch?v=SA1SxZoFmOU) (Now we're talkin'!) So, how high can it go? A geologist, a physicist, and a priest walk into a bar... I have no idea how high the variation can go, and the reason I used the traditional joke lead-in is that we may be dealing with a guess on the order of having faith. My EE background suggests that variation below 3% can generally be ignored. That suggests that we could handle up to +/- 30 Gal. Maybe more depending on exactly how materials are distributed through the planetary body. Maybe. But, let's stick with tried-and-true statistics. I'm going to go out on a limb and suggest that +/- 30 Gal (that's +/- 3% and 600X what we experience now) is the max variation before the Ring of Fire turns the Pacific Ocean into the biggest [Shabu-Shabu](https://en.wikipedia.org/wiki/Shabu-shabu) dinner in history. Would we be able to feel it? Maybe. But considering how much distance must be crossed to reach the high and low points, probably not. It does represent a difference of about +/- 1.3 ft/s2, but I expect that's below the threshold of feeling. --- Edit Mark Olsen correctly pointed out that I misread the table in the Wiki article. I've updated my answer to correct for it. Thanks, Mark. [Answer] @JBH's answer is a good one, but but I think it is based on an error: A gal is not one g, but 10\\-3 g, and a milligal is 10\\-6 g, so JBH's comments about the anomalies in the OP's question seeming high is spot-on. But pretty much everything he said is still good physics, it just needs to be scaled. (For a good article on the subject, see [this paper](http://www-gpsg.mit.edu/12.201_12.501/BOOK/chapter2.pdf)) There are a couple of other effects to consider: Increased gravity in one area pulls both water and rock towards it and away from areas of lower gravity -- it flows/rolls downhill! -- until sea level has the same gravitational potential everywhere. So adding potential differences will change the topography. Basically, it affects the geoid. Much more important than that is the effect of a loss of rotational symmetry. A lumpy body does not rotate smoothly, but can tumble chaotically. (Saturn's satelliey Hyperion does just this. See [this article](https://www.britannica.com/place/Saturn-planet/Orbital-and-rotational-dynamics).) Chaotic tumbling would produce some pretty extreme effects with days and seasons and directions being essentially unpredictable! [Answer] To keep things very simple, let's define habitability for a point at the surface of the planet as having Earth-like gravity, air pressure, air composition, temperature and some water. Important gravity variations can be found on fast-rotating worlds, close or contact binary planets, or on torus worlds - torus worlds probably won't be naturally formed, though. Those can vary from a theoretical zero for near-contact binary with negligible separation, to several g. But there will be points where the gravity is habitable. Air composition doesn't directly depend on gravity, as long as it is high enough to keep enough atmosphere - but if there are points where gravity is Earth-like, it should be enough. Sure, even Earth atmosphere slowly evaporates, but you can either refill it, take a young world or take one that (like Earth) is big enough so it won't be a problem before many, many billions of years. Similarly, temperature will mostly change with distance to and type of star(s), not surface gravity. Air pressure and water are interesting. You would expect it to vary, with atmosphere and oceans to pool at the highest gravity points. But in fact, it will be everywhere the same. Look at it this way: at those scales, even rock acts as a liquid (hence why worlds are mostly spherical, though those particular ones are much less so) and would have already flown there if it was possible. Hence, everywhere, the surface is horizontal even if the strength of gravity can vary. So water and air will still flow everywhere and equalise at the whole surface. Atmospheric composition can indirectly be interesting, though: air may evaporate faster at low gravity points, but high gravity points will be able to retain lighter gas. So you could have a younger planet retaining hydrogen or helium in its atmosphere for a long time, something Earth couldn't. tl;dr: Even major gravity variation will have little impact on the possible habitability of earth-like gravity points. This is, of course, ignoring the potentially catastrophic effects fo gravity varying in time. But whatever is making gravity varying so fast is probably its own catastrophic problem anyway. [Example of close binary planet, with surface gravity map](http://panoptesv.com/RPGs/Settings/VergeWorlds/Worlds/Bondle.php) [Torus-shaped planets](http://www.aleph.se/andart/archives/2014/02/torusearth.html) ]
[Question] [ Working on a creature with a very strange mouth. He has a vertical jaw, compared to the human horizontal, as well as they have "two" tongues, imagine a snake's forked tongues where the splitting point is inside of the throat. The tongues can extend three to four inches beyond the mouth. Assume the everything except for the mouth and the tongues are the same in the creatures as humans. My question is: What sounds would this jaw and tongue not allow for which are used in human speech, and what sounds could they possibly make which humans cannot make? [Answer] # S and Th are going to be problematic The IPA describes every consonant the human head and throat is capable of making. Characters to the left of the below chart represent sounds made further forward in the mouth. Characters to the right are sounds made further back in the throat. Assuming that the rear portion of this creature's mouth are very close to a human's then the sounds on the right side of the chart should be pretty close. Given the split tongue, this creature is going to have greater difficulty articulating sounds in the Fricative row as almost all those sounds involve some amount of air flow over the tongue. Since this creature's tongue isn't the same as a human's, we should expect a slightly different sound. The presence of lips and nasal cavity means that Plosives and Nasal rows should still be pronoucable by this creature. [![IPA Alphabet](https://i.stack.imgur.com/Sy7L1.gif)](https://i.stack.imgur.com/Sy7L1.gif) Also, read up on [formants](https://en.wikipedia.org/wiki/Formant) which talk about how vowels are formed. Holy crap, human speech is specialized! Sure, if you've got the software to simulate this, great but just looking at the IPA chart and feeling around with your own head should be a pretty good start. [Answer] This is such a deviation from a normal human mouth that we are unable to describe what sounds can be produced without a detailed simulation of air pressure within the creature's head and neck. Linguists that focus on the physiology of how we produce sounds for speech have a concept called [places of articulation](https://en.wikipedia.org/wiki/Place_of_articulation). In a nutshell this is describing the places in the vocal tract that are constricted during the production of a consonant sound. Many of these locations wouldn't exist in a vertically oriented mouth. There are humans that have modified their tongue to be split into two halves. They can experience difficulties properly restricting air. You can read more about tongue bifurcation from a linguistics perspective [here](http://linguistics.ubc.ca/bifurcation/). [Answer] Don't forget to consider how much control is exerted over those tongues. Is it like a dog's tongue that can move backwards or a regular human tongue. I'm guessing a more prehensile tongue would have an even more alien sounding range of vowels and consonants. ]
[Question] [ To clarify, I'm not talking about electronic computation. Instead, the question is as to what barriers would prevent a medieval society from building something in the vein of a Jacquard Loom, or Analytical Engine style system to a massive scale? This intuitively feels out of the range of possibility of me, but can't quite concretely figure out why. Edit, a note on utility: While it might be trivial to create a tiny system that technically qualifies as turing complete, I'm more interested in something that could run complex algorithms (like A\* search, tax computation, resource allocation systems, cryptography, even basic ML) to lend superhuman power to the administration of your nation-state, or theocracy, or totalitarian premodern empire. [Answer] Machine like this [Pascals Calculator](https://en.wikipedia.org/wiki/Pascal%27s_calculator) (circa 1652) can be easy used for calculating taxes. [![Pascals Calculator](https://i.stack.imgur.com/O7EJG.jpg)](https://i.stack.imgur.com/O7EJG.jpg) With medieval level of technology making small and precise gear wheels can be quite hard, so probably gears was little bigger that in Pascal's machine - like gear wheels from Salisbury Cathedral Clock circa 1386 year: [![Salisbury_Cathedral,_medieval_clock](https://i.stack.imgur.com/hblAk.jpg)](https://i.stack.imgur.com/hblAk.jpg) There is a [text](https://en.wikipedia.org/wiki/Verge_escapement) about this clocks. If me take about 10 clocks mechanisms like this, we can make something close to Pascal's calculator (but with few peasants/slaves used for motivation of device). Other possible usage of such machines can be processing statistics - see [tabulating machine](https://en.wikipedia.org/wiki/Tabulating_machine). In general, i think even castle sized Thinking Machine had maximum all the computing power of 1980 years calculator. UPD1 : there is an other solution to make Thinking Machine with medieval level tech. You just need to gather few dozens of people who can write, read and count using pen and paper and [abacuses](https://en.wikipedia.org/wiki/Abacus) - and made a [human computer](https://en.wikipedia.org/wiki/Human_computer) from them. I'll try to find a link, but as far as i remember my historical classes, in Medieval Russia monks in monasteries were ordered record when anybody was born, record marriages, and record deaths of people in surrounding settlements. This was used to gather statistics for Tzar's for strategical planning and deduct where paying taxes were not carefull. So, the medieval monastery can be easiy used as Monk Powered Thinking Machine. Just provide them with food, parchment, pencils, and of course, data and algorithm to process it. UPD2: other uses of Medieval Thinking Machine (both mechanical or monk powered) is cryptography - for example, they can use something like [Vigenère cipher](https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher) or [Caesar cipher](https://en.wikipedia.org/wiki/Caesar_cipher). So, they can create/read encrypted messages to/from vassals, even decrypt messages of rivals. To use Ceasar or Vigenère ciphers, you just need pen and paper and you can produce really hard to encrypt messages. [Answer] Define computer. An [abacus](https://en.wikipedia.org/wiki/Abacus) helps you compute, and this device has been around since 2,700 BC. With just a bit of mechanical engineering knowledge you can build something more sophisticated. The [Antikythera device](https://en.wikipedia.org/wiki/Antikythera_mechanism) was a machine based on cogs and levers that could the position of planets and the Moon and predict eclipses, as well as tracking other interesting astronomical stuff. The date in which it was built is still up to debate but all historians and scientists that researched it agree that it is from the BC era, between 205 to 87 BC approximately. Some nerd gods decoded how the cogs connected and made a functional, LEGO equivalent device a few years back; it's a treat to the eyes and mind to see. [Here is a video of it](https://www.youtube.com/watch?v=RLPVCJjTNgk), and below is a picture: [![A LEGO device that is computationally equivalent to the Antikythera device.](https://i.stack.imgur.com/MjecR.jpg)](https://i.stack.imgur.com/MjecR.jpg) The only thing keeping medieval western societies from replicating this feat is the phobia of reason typical of the middle ages. Other societies had their own mechanical computers; [Persians developed a mechanical, geared astrolabe in the 13th century](https://en.wikipedia.org/wiki/Astrolabe#Medieval_era). [Answer] > > What would a Medieval Logic Machine (Computer) need to be feasible? > > > A need for inventing "A\* search algorithm". First you need the basic equation on which people would invent machine to calculate it faster/better. You can't introduce a solution before even the problem is discovered (ok, you can but that's called low-level corporationism). So for such machine to exist you would need math on level that allows to create and solve complex algorithm. [Answer] The value of modern computers is in processing huge amounts of data. However, medieval tech would be unlikely to mass produce "machine readable " data such as reams of census data for cross tabulation. What such calculators were good for would be to create technical data- trig and log tables to 4 or 6 digits, let's say. First, read Stirling's The Difference Engine, steampunk for Babbage age computers. Look at the tech that did emerge... IBM punch cards were originally data storage for the US census at the turn of the century. I have a Curta calculator my dad bought in 1957 - a 12 digit hand cranked calculator the size of a pop can. The issue may be precision tech, but it is also regarding demand. Fine gears were a side effect of the clock, then the watch industry' but who needed a clock more accurate than the hour in the dark ages? It's all about demand. When everyone important started using clocks and scheduling things to the minute, the industry learned to mass produce. But precise clocks originally were needed mainly to determine longitude - what time GMT did the sun rise where you were? That need arose when ships started sailing outside familiar smaller seas, out into the Atlantic and further. So what would drive your society to want to make calculators? So much so, that someone would spend a small fortune on proof of concept? (Read Clarke's Nine Billion Names of God ) Perhaps in that vein, the church needs it to enumerate primes because they think that each prime number is a holy manifestation? Maybe they use it to calculate celestial events? After all, skilled craftsmen don't come cheap and the thing with medieval times, especial in Europe, is that the various states were small and relatively poor, not to mention lacking the critical mass collection of educated types to design and build such a thing. Plus, there's the holdover Greek / Roman concept that scholars didn't soil their hands with manual labor like mechanical assembly. [Answer] ## Computing (at least) The notion of algorithm, as we know today, is from the 20th century, borne from a body of previous mathematical research. Middle age scholars would never think about an algorithm for finding a shortest path. For actual computing, the best bet would be human computers: people with quills, paper, and abacus, working in parallel, under the supervision of a mathematician. [Answer] Opening: "what barriers would prevent a medieval society from building something in the vein of a Jacquard Loom, or Analytical Engine style system to a massive scale?" The two examples would have no purpose in medieval times Jacquard Loom invented his textile machine, to be able to weave complicated decorative designs in large quantities. This was a result of fashion habits in the 17th century. In the 15th century, textiles were painted in one color and sold to the customer. When Babbage invented his general purpose computer in the 19th century, his work was based on theoretical mathematics developed by Ada Lovelace. They worked together. In medieval times, there was no scientific method.. the mathematics known at the time mainly involved calculus.. so there was no incentive for building an Analytical Machine in medieval times. Same problem Babbage himself experienced ! his machine was never built. Ok so there was no medieval computer ? There certainly were.. for example the [astronomical clock](https://en.wikipedia.org/wiki/Astronomical_clock) shown above by vodolaz95 could be regarded as a single algorithm computer.. even overly complicated, because it did not use a solar-centric system. The medieval world could have used computers to help e.g. convert different coinage values.. but if you look at the actual practice of [coin weighing](https://consent.google.com/m?continue=https%253A%252F%252Fwww.google.com%252Fsearch%253Fq%253Dmedieval%252Bcoin%252Bscale%2526tbm%253Disch%2526source%253Diu&gl=NL&m=0&pc=irp&uxe=eomtm&src=1), it focussed on weighing the amount of silver or gold, and multiply that with some fixed day price. This calculation is performed in the same way every time and does not require division, like percentages do. So it was done manually. A more complex medieval algorithm did exist, which involved the calculation of the date of Easter. That algorithm originated from the papal court, the Vatican decided it. Priests had an [arithmetic ruler](https://en.wikipedia.org/wiki/Slide_rule) to calculate the proper date. Let's add a picture, [![enter image description here](https://i.stack.imgur.com/K28QU.jpg)](https://i.stack.imgur.com/K28QU.jpg) <https://erikkwakkel.tumblr.com/post/52983418486/medieval-computer-this-is-a-volvelle-a-medieval> ]
[Question] [ Using today's (real) genetic engineering methods, would it be possible to engineer a horse with a single spiral horn? Maybe rub a horse on a narwhal? I know mythical Unicorns have other "powers", but in a simple sense, I want a white horse with a horn. [Answer] You might be better off starting with a goat rather than a horse. There certainly have been single-horned goats. Breed them until you find some that breed true. This would also explain why the unicorn has goat hooves. And it allows the unicorn to be developed with simple breeding rather than genetic engineering. You might have some extra work to make the unicorn large enough to ride. I.e. you might need to breed multiple generations to concentrate on size, strength, and speed to make them more horse-like. Sorry, no solution for making the one-horned goat prefer virgin riders. [Answer] There is no reason to believe such a creature cannot exist. For all practical reasons, a creature like that is possible with some genomix and playing around with the bone structure DNA of the head region. [![narwhal](https://i.stack.imgur.com/YZEsc.png)](https://i.stack.imgur.com/YZEsc.png) If a bizarre animal like narwhal can exist, why not a horse with a horn? [![unicornfish](https://i.stack.imgur.com/ief2h.png)](https://i.stack.imgur.com/ief2h.png) And there's even a fish that has a forehead horn. It's no amazement it's known as Unicornfish! [![rhinoceros](https://i.stack.imgur.com/PP9SC.png)](https://i.stack.imgur.com/PP9SC.png) And then there was your favorite Elasmotherium! Giant, magnificent and extremely bad tempered. You won't want to meet him face to face in the wild. That's probably why they are extinct now. Anyhow, the point is that it is possible to have unicorn-like horses in reality if you fiddle with their genes controlling the shape of their heads. [Answer] One of the things you need to realize, is that horn is not always bone. In the case of rhinos, it is actually a clump of modified hair, like the plates of a pangolin(google it) which are also horns. The second thing is that narwhals do not have horns but a tusk, a modified tooth. This fact actually makes the process somewhat easier as all you have to do is insert a gene that makes the hair on the horses head form into horn (not actually simple but probably easier than reforming its skull). You could use goat DNA to make this gene, though anything you do will make your horse look strange after altering. Your unicorn would look even more weird were you to go with the narwhal approach, though the horn would be he right shape. To be more specific, the male narwhal, when mature, has its front-left tooth grow forward, through the top of its lip and out in-front of its body, less charming then the usual illustrations you see. This would actually be, maybe the easiest way to give a horse a 'horn', though its a tusk, even if it looks absolutely stupid. ]
[Question] [ What exactly happens to leather armor in different environmental conditions, for example battles or long exposure to rain or desert heat? What can be done to negate or care for it? [Answer] I have one, and I did wear it with several weather (for medieval feast). Rain and water : Rain and water change its color (making it darker). It's not too bad when it's wet, but it's hard to dry it without destroying it. While drying, it becomes harder. If you bend it while it's wet and let it dry, it's very hard to have it soft again. It's all twisted. If you ruin the color, don't expect to have the same color again. You can easily make it darker, but with water (and sweat...) you will have marks everywhere (For a medieval armor, that's actually not bad) In order to avoid the hardening, you have to oil it before rain, with linseed oil at best (it make it darker too), or anything fat enough (shoe polish is not bad). Then make it dry without heat (no flame, no warming, let it dry slowly), not bended, and oil it again. Heat : Heat makes you sweat, and sweat is salty, and it's the worst. Heat itself don't ruin the leather. If it becomes too dry, grease it. But the sweat makes white and wet halos everywhere. Don't use water to remove the salt. Oil or grease, again. Even a very old and maltreated leather can become something beautiful if you grease it enough ! [Answer] Leather is the tanned version of skin, so to some extent, you can see the effects of weather on your own skin. In hot weather, leather tends to dry and crack, which results in it being less durable and more prone to tearing, it would also become more stiff and rigid (thus rather uncomfortable to wear) as well as losing some of its waterproof properties. The best way to solve that is by moisturising it, the same way you would do with your hands. Depending on the time and setting of your world, there are several products that can be used. If it's set in the past, your people could use oils (whether of animal or plant nature) to rub into it. If this takes place in the future, you could be more liberal about the choice of product (they could still use natural oils, but also stuff like shoe polish or even specialised products). Water is not good for leather either. Although leather does tend to be more waterproof than other fabrics, water will get through it eventually and it will, again, lead to a loss of durability. You can read a whole article about how to take care of leather in damp conditions here: <http://www.leathertherapy.com/pages/Waterproofing-Leather-.html> As for the way it behaves during battle, ultimately that comes down to how much action it sees, whether you get hit by the enemy, whether there is fire involved as or even chemical weapons. At the end of the day, there isn't an exact number of weeks/months to say how long a weather armour will last for, because it depends greatly on the type of battle that is going on (whether it's a siege that lasts for months or even years, or just a skirmish, and so on). [Answer] What kind of leather armor? It is supple leather that is padded and worn rather like clothing? Is it thick leather that has been hardened and used like plate? After doing medieval reenactments for years I have experience with both. The person's sweat can soak into supple leather and leave white marks anywhere it touches. Heat can make the wax hardened leather softer. Armor that is allowed to get damp and not dry out properly can grow mold. It will smell like the nastiest gym bag ever. As the other commentators have mentioned cleaning, drying, and oiling leather equipment keep it in good shape, water resistant, and long lasting. In a long campaign or siege without the time or materials to do this properly you'll have straps breaking. Edges will curl and deform making the armor less comfortable. The surface will be rough up and not smooth. Sweat stains will obscure heraldic markings. [Answer] I just treat it like a saddle. With saddles you wash them with saddle soup and water then let it dry, after that use a saddle oil. If you want water proofing, then put a layer of mink oil on after the saddle oil has dried up and the leather has become flexible. I never used hardened leather so not sure how that would work, might make it soften up. ]
[Question] [ Rules: 1. No magic 2. Eat, drink, and breathe air (mammal/reptile(amphibian ok)) 3. Intelligent life form (no jellyfish or single-celled organisms) 4. No artificial hearts (unless really ingenious, no swapping) My thought: A creature's veins/arteries were circuits and pulsed (kinda like esophagus bringing food to the stomach, except on a smaller scale). The veins would circle around the lungs and absorb oxygen and then distribute oxygen as it was pushed along. This idea is based loosely on the [artificial heart that doesn't beat](http://www.popsci.com/science/article/2012-02/no-pulse-how-doctors-reinvented-human-heart) (summary=continuous-flow artificial heart). Is it feasible for a foreign/alien creature to survive without a heart? Also are there any drawbacks to not having a biological heart or strange side effects? To clarify, blood is not a necessary requirement if they can act intelligently. However, the creature must be organic/living: no AI robots. In my mind, a creature without a specific local organ to push blood/oxygen to its muscles would be harder to kill. It could still bleed to death as blood should be flowing in some manner to muscles, but there would be no particular spot to target to kill it instantly (excluding maybe the head, since there is no heart). [Answer] Could one survive without a heart? Quite possibly. Assuming that is restricted to a single muscle whose job is to move a liquid around the body to move nutrients, gases and wastes. Most animal-like things would need to have a delivery system to move things around. In replacement of a heart, all the bodies muscles could be used to move the 'blood'. All the veins/arteries could have frequent one-way valves. So the blood would have a round trip and as the animal moves it forces the blood to move. Not moving an arm, then the blood quits moving. They would likely be more like reptiles in physiology, since metabolism changes a lot. The animal would also need to have some 'reactions' like breathing to keep a minimal amount of blood flow to vital areas. If these aren't 'cold-blooded' then they will need a LOT more food/body mass, since they won't have 1 organ tasked with circulation. [Answer] I don't think this is possible without a biochemistry very different than what we've seen on Earth. However, we don't know what life would look like if it was not carbon-based or oxygen breathing, so let's stick with those. First of all, what does intelligence require? A lot of processing power. In humans, [15% of our blood flow goes to the brain](https://en.wikipedia.org/wiki/Cerebral_blood_flow). We need to be able to get this blood to the organism's CPU (the brain, in our case), and then back to the oxygen intake system (our lungs). Here's where we start running into problems - the gas exchange needs to happen in an area with low blood pressure. The gas exchange can't happen if the walls of the blood vessel are too thick, so there's only so much pressure they can handle before a [pulmonary edema](https://en.wikipedia.org/wiki/Pulmonary_edema) would start to form. FYI, [this is the case in fish as well](http://esi.stanford.edu/circulation/circulation7.htm), so being aquatic doesn't eliminate this problem. What if the creature has a low blood pressure everywhere? It's not going to be able to pump blood everywhere in its system, especially not its energy-hungry CPU. Having arteries themselves pumping the blood isn't going to work - the blood looses oxygen along the way in order to power the artery-pumps. One way to get around this is having a small size - with less distance to travel, the blood pressure doesn't need to be as high for the blood to get to all of the body. Unfortunately a smaller size limits the maximum size of the creature's brain, meaning that there would be a limit to how intelligent it could be. A size small enough to not need a heart would not have enough processing power to truly be intelligent. So this naturally means that the creature needs to have areas of high blood pressure, and areas of low blood pressure. This requires some sort of pump to increase the blood pressure - a heart. Are there any other ways around this? I can think of at least one - multiple air intakes. However, this comes with its own problems. The biggest one is [disease](https://en.wikipedia.org/wiki/Airborne_disease). If you have multiple air intakes, that means you have more avenues for disease to attack and that your body has to keep defended. It would also be a vulnerability that other types of parasites could exploit. So what about if disease and parasites didn't exist on a particular world? Evolutionary pressure must not be very high on a world like that, otherwise niches like that would be filled. Without evolutionary pressure, intelligent life wouldn't exist - intelligence is physiologically expensive, so it is only going to exist if there is some environmental pressure that it is able to relieve. What about different biochemistries? As I said, we've never seen anything that's not oxygen breathing and carbon-based, so we don't know what it would look like. If you're going into the realm of non-carbon-based lifeforms, it would be reasonable to handwave away the need for a centralized heart. [Answer] In fact almost any muscle movement affects circulation somewhat. When you are walking or running, your legs aid your heart enormously by their pumping effect. > > The skeletal-muscle pump is a collection of skeletal muscles that aid > the heart in the circulation of blood. It is especially important in > increasing venous return to the heart, but may also play a role in > arterial blood flow. > <https://en.wikipedia.org/wiki/Skeletal-muscle_pump> > > > [![enter image description here](https://i.stack.imgur.com/hIaNT.jpg)](https://i.stack.imgur.com/hIaNT.jpg) ... All you have to do is go into a suspended animation state instead of sleep (this would be like hibernation). The rest of the time you would just have to keep on the move - the faster you run, the faster you can run. I think this lifestyle would suit predators best. Lion-like (or cheetah-like) creatures could spend 95% of their day sleeping, then a quick warm-up before chasing the bejesus out of everything in sight. Fill your stomach and then straight back to sleep. The enzymes will continue to work even though you are not running around. Whilst resting, your stomach muscles could produce a slow, blood-pumping action whilst you digested your food. [Answer] Just to clarify before I continue this answer: I'm ignoring the mammal/reptile requirement in favour of the 'blood isn't necessary' requirement, as any creature that has no heart isn't going to easily fit into our normal tree of life. It might possibly be a shrub somewhere. Or a mushroom. With that said: One potential (though unlikely) solution might be the generation of 'self aware' emergent intelligence in something like a man-o-war style colony. If this process proceeds long enough for all the creatures involved to be entirely co-dependant then it may be classified as one creature, despite being made from several. This creature could be either ocean going or land-bound (my personal favourite environ for it would be a tidal estuary) and would be mostly sessile. It's also worth noting that the 'intelligence' would be distinctly different from ours, but no less valid. In this creature there are many organisms, some of which prevent predation, some of which are responsible for luring/ensnaring prey, and some of which (the most interesting ones) exchange biochemical signals with each other and the other organisms in such a way that they can solve complex problems/ be aware that they are a thing. Imagine an ant colony, but with the ants being microscopic, numbering in the billions and having had some serious pressure to evolve more complex problem solving mechanisms. This organisation would have a distinctly different structure to a human brain, potentially manifesting as a constantly shifting sense of self, no discernible personality, or very short term memory when not actively working to resolve a problem. It's possible that this creature would have no interest in putting a jigsaw puzzle together if you asked it to, but would solve a 12x12 Rubik's cube to get some food from the middle of it. It would also have some serious processing lag. While it might be able to reconfigure to solve hideously complex problems, the signal delay between individual cells not bound into a structure like our brains are would approach situations in a dreamlike fashion. Don't expect fast reflexes. This creature would have no 'heart', no 'brain' and no 'hands'. Some organisms might be responsible for nutrient transfer, but if it's similar to a man-o-war there would be no distinct resource transfer network, just an organisation of specialised cells that can be re-organised by the emergent intelligence as best required. Some organisms work together to solve problems and keep every other organism (and themselves) alive, but loss of a section of them will be patched up by the others (though it might cause confusion). Some organisms might be great at organising into temporarily strong structures for object manipulation, but without guidance from the 'brain' cells they'd just form a lichen-like blob. It would be extremely weird to watch this beast doing anything. Imagine this thing trying to use a can opener on a tin of spaghetti. It would pull the can and the opener into itself, take a few seconds experimenting, then open the can inside itself before drawing the spaghetti and sauce out into a slowly diffusing mass of nutrients. Movement would be less of an active 'I am going here now' and more of a gradual relocation, like watching a banana tree move, or tracking a city over the course of millennia. TL:DR: Beached man-o war/Uber-ant colony. No heart as it's distributed, intelligent because it's got complex emergent behaviour, and can eat/drink/breath/manipulate, just really weirdly. [Answer] Suppose you drank with your feet, and steamed off with your head. Interstitial fluid is then being drawn upwards by osmosis or vacuum forces as the water evaporates. This continuous flow of water carries nutrients through-out the entire body. If you want to use your arms, then you would also need to take a drink with your hands. You wouldn't need veins as such, just a network of capillaries. [Answer] # Peristaltic blood vessels. Increase slightly the outer diameter of the tunica of all major blood vessels, and have them pulse according to an internal pressure-controlled feedback loop. Human beings have already all the required organs and subsystems, so we know that it is possible. All arteries are surrounded by a smooth muscle layer, that contracts and releases once per second (this might be too much for smooth muscle, and we might require striated or cardiac muscle fibers), and generate a pressure wave traveling at about 1 meter per second. You have now a heartless circulating system with no single point of failure, as far as pumping is concerned. The muscle work to contract about 5 millimeters against a pressure of 150 mmHg (0.2 kg per cm2) over a surface of around (my estimate) 2400 cm2 is 0.005\0.2\2400 = 2.4 N, so we're talking of less than 3 W (which is consistent with the fact that a low-efficiency thermodynamic capacitor for an artificial heart [was estimated to require 16W of thermal power](https://patents.google.com/patent/US3434162)). So, the energy and oxygen requirements of the "distributed heart" are negligible and can be easily satisfied by the existing supply methods. [Answer] Bugs, insects, and many invertebrates do not have hearts, not even a complete circulatory system. Instead, they diffuse oxygen throughout their bodies via microtracheae, which pulsate to make their bodies a little like a giant lung. This is why you can not drown an ant or a cockroach by submerging their heads. Bugs sometimes have a heart for pumping hemolymph, or basically highly concentrated fuel rich bug-blood that works mostly via diffusion. Worms and a lot of smaller bugs do not have any form of significant heartbeat (though many have a primitive heart-like organ to stir the hemolymph around) or any significant blood pressure (as the blood does not carry oxygen). You can easily scale up such a system by having baffles around the trachea that constantly stir or move the hemolymph, or having other organs (or constant bodily motion of the body walls) that pump this liquid around. Bugs actually do get large in some places. For intelligence, just make your atmosphere oxygen-rich or increase the pace of the pulsating trachea, and having multiple nerve ganglia instead of a single solid brain. There are already working examples of such life being perfectly immune even with this multi-intake scheme. There are insects, after all. Because of this form of respiration, bugs are actually defined as bloodless by certain Semitic traditions. ]

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